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Sample records for ac microsized gliding

  1. AC electric field for rapid assembly of nanostructured polyaniline onto microsized gap for sensor devices.

    PubMed

    La Ferrara, Vera; Rametta, Gabriella; De Maria, Antonella

    2015-07-01

    Interconnected network of nanostructured polyaniline (PANI) is giving strong potential for enhancing device performances than bulk PANI counterparts. For nanostructured device processing, the main challenge is to get prototypes on large area by requiring precision, low cost and high rate assembly. Among processes meeting these requests, the alternate current electric fields are often used for nanostructure assembling. For the first time, we show the assembly of nanostructured PANI onto large electrode gaps (30-60 μm width) by applying alternate current electric fields, at low frequencies, to PANI particles dispersed in acetonitrile (ACN). An important advantage is the short assembly time, limited to 5-10 s, although electrode gaps are microsized. That encouraging result is due to a combination of forces, such as dielectrophoresis (DEP), induced-charge electrokinetic (ICEK) flow and alternate current electroosmotic (ACEO) flow, which speed up the assembly process when low frequencies and large electrode gaps are used. The main achievement of the present study is the development of ammonia sensors created by direct assembling of nanostructured PANI onto electrodes. Sensors exhibit high sensitivity to low gas concentrations as well as excellent reversibility at room temperature, even after storage in air. PMID:26009866

  2. Teleseismic S wave microseisms.

    PubMed

    Nishida, Kiwamu; Takagi, Ryota

    2016-08-26

    Although observations of microseisms excited by ocean swells were firmly established in the 1940s, the source locations remain difficult to track. Delineation of the source locations and energy partition of the seismic wave components are key to understanding the excitation mechanisms. Using a seismic array in Japan, we observed both P and S wave microseisms excited by a severe distant storm in the Atlantic Ocean. Although nonlinear forcing of an ocean swell with a one-dimensional Earth model can explain P waves and vertically polarized S waves (SV waves), it cannot explain horizontally polarized S waves (SH waves). The precise source locations may provide a new catalog for exploring Earth's interior. PMID:27563094

  3. Earthquake Prognosis With Applied Microseism.

    NASA Astrophysics Data System (ADS)

    Ahmedov, N.; Nagiyev, A.

    Earthquakes are the most dangerous natural catastrophy in terms of numerous casualties, amount of damages, areal coverage and difficulties associated with a need to provide secure measures. Inability to forecast these events makes the situation worse due to the following circumstances:-their buried focuses are invisible in the subsurface, they occur suddenly as a thunder, and some tens of the seconds later they leave devastated areas and casualties of tens of thousands of people. Currently earthquake forecausting is actually absolutely inefficient. Microseism application is one of the possible ways to forecast earthquakes. These small oscillation of up-going low-ampitude, irregular wawes observed on seismograms are refered to as microseism. Having been different from earhquakes itself, they are continuous, that is, have no origin coordinate on time axis. Their occurence is associated with breakers observed along shorelines, strong wind and hurricane patterns and so on. J.J.Linch has discovered a new tool to monitor hurricane motion trend over the seas with applied microseism recorded at ad hocstations. Similar to these observations it became possible to monitor the formation of the earthquake focuses based on correlation between low-frequency horizontal ahannels'N-S and E-W components. Microseism field and preceding abnormal variations monitoring data derived from "Cherepaha" 3M and 6/12 device enable to draw out some systematic trend in amplitude/frecuency domain. This relationship observed in a certain frequency range made it possible to define the generation of earthquake focuses with regard to the monitoring station. This variation trend was observed while Turkish and Iranian events happened during 1990,1992, and 1997. It is suggested to be useful to verify these effects in other regions to further correlate available data and work out common forecausting criteria.

  4. The bacterial gliding machinery

    NASA Astrophysics Data System (ADS)

    Shrivastava, Abhishek

    Cells of Flavobacterium johnsoniae, a rod-shaped bacterium, glide over surfaces with speeds reaching up to 2 micrometer's. Gliding is powered by a protonmotive force. The adhesin SprB forms filaments about 160 nm long that move on the cell-surface along a looped track. Interaction of SprB filaments with a surface produces gliding. We tethered F. johnsoniae cells to glass by adding anti-SprB antibody. Tethered cells spun about fixed points, rotating at speeds of about 1 Hz. The torques required to sustain such speeds were large, comparable to those generated by the flagellar rotary motor. Using a flow cell apparatus, we changed load on the gliding motor by adding the viscous agent Ficoll to tethered cells. We found that a gliding motor runs at constant speed rather than constant torque. We attached gold nanoparticles to the SprB filament and tracked its motion. We fluorescently tagged a bacterial Type IX secretion system (T9SS) protein and imaged its dynamics. Fluorescently tagged T9SS protein localized near the point of tether, indicating that T9SS localizes with the gliding motor. Based on our results, we propose a model to explain bacterial gliding.

  5. Array Analysis of North Atlantic Microseisms

    NASA Astrophysics Data System (ADS)

    Craig, David; Bean, Chris; Möllhoff, Martin; Donne, Sarah; Lokmer, Ivan; Le Pape, Florian

    2016-04-01

    Oceans generate persistent low frequency background seismic signals known as microseisms through a mechanical coupling with the Earth's crust. Microseism energy originates as regions of low barometric pressure (depressions) over the oceans where it is transmitted to the sea-floor and propagates as elastic energy in the Earths crust. Consequently microseisms carry important meteorological information relating to both the atmosphere and the hydrosphere. The significance of microseisms as climate indicators has previously been investigated in several studies (Essen et al., 1999; Aster et al., 2010) and to estimate ocean wave parameters using onshore seismometer data (Bromirski et al., 1999). Also many modern seismological methods make use of microseism signals, for example "noise tomography" (Shapiro et al., 2005); spectral ratio techniques ; and cross-correlation techniques (Wapenaar et al., 2011; Brenguier et al., 2014). The continental shelf near Ireland is a known generation are for microseisms and an important region for European weather forecasting and climate studies. There has also been seismometers in the region since the 1960s. There is a single station in Valentia observatory in south-west Ireland and a small scale seismic array in Scotland which offer potential climate records for the region. To make use of this information it is first necessary to understand how microseisms recorded in Ireland relate to the local ocean wavefield. The WAVEOBS project was set established with three primary goals; to get a better fundamental understanding of microseism sources; to investigate the use of ocean generated microseisms as real time ocean wave height data; and to investigate their use as a climate proxy. Using spectral analysis and array methods the microseism wavefield in the North-East Atlantic near Ireland is described with reference to the ocean wavefield.

  6. Optical diagnostics of a gliding arc.

    PubMed

    Sun, Z W; Zhu, J J; Li, Z S; Aldén, M; Leipold, F; Salewski, M; Kusano, Y

    2013-03-11

    Dynamic processes in a gliding arc plasma generated between two diverging electrodes in ambient air driven by 31.25 kHz AC voltage were investigated using spatially and temporally resolved optical techniques. The life cycles of the gliding arc were tracked in fast movies using a high-speed camera with framing rates of tens to hundreds of kHz, showing details of ignition, motion, pulsation, short-cutting, and extinction of the plasma column. The ignition of a new discharge occurs before the extinction of the previous discharge. The developed, moving plasma column often short-cuts its current path triggered by Townsend breakdown between the two legs of the gliding arc. The emission from the plasma column is shown to pulsate at a frequency of 62.5 kHz, i.e., twice the frequency of the AC power supply. Optical emission spectra of the plasma radiation show the presence of excited N2, NO and OH radicals generated in the plasma and the dependence of their relative intensities on both the distance relative to the electrodes and the phase of the driving AC power. Planar laser-induced fluorescence of the ground-state OH radicals shows high intensity outside the plasma column rather than in the center suggesting that ground-state OH is not formed in the plasma column but in its vicinity. PMID:23482171

  7. Gliding Direction of Mycoplasma mobile

    PubMed Central

    Morio, Hanako; Kasai, Taishi

    2015-01-01

    ABSTRACT Mycoplasma mobile glides in the direction of its cell pole by a unique mechanism in which hundreds of legs, each protruding from its own gliding unit, catch, pull, and release sialylated oligosaccharides fixed on a solid surface. In this study, we found that 77% of cells glided to the left with a change in direction of 8.4° ± 17.6° μm−1 displacement. The cell body did not roll around the cell axis, and elongated, thinner cells also glided while tracing a curved trajectory to the left. Under viscous conditions, the range of deviation of the gliding direction decreased. In the presence of 250 μM free sialyllactose, in which the binding of the legs (i.e., the catching of sialylated oligosaccharides) was reduced, 70% and 30% of cells glided to the left and the right, respectively, with changes in direction of ∼30° μm−1. The gliding ghosts, in which a cell was permeabilized by Triton X-100 and reactivated by ATP, glided more straightly. These results can be explained by the following assumptions based on the suggested gliding machinery and mechanism: (i) the units of gliding machinery may be aligned helically around the cell, (ii) the legs extend via the process of thermal fluctuation and catch the sialylated oligosaccharides, and (iii) the legs generate a propulsion force that is tilted from the cell axis to the left in 70% and to the right in 30% of cells. IMPORTANCE Mycoplasmas are bacteria that are generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide. Although these species appear to consistently glide in the direction of the protrusion, their exact gliding direction has not been examined. This study analyzed the gliding direction in detail under various conditions and, based on the results, suggested features of the machinery and the mechanism of gliding. PMID:26503848

  8. Multidecadal climate-induced variability in microseisms

    USGS Publications Warehouse

    Aster, R.C.; McNamara, D.E.; Bromirski, P.D.

    2008-01-01

    Microseisms are the most ubiquitous continuous seismic signals on Earth at periods between approximately 5 and 25 s (Peterson 1993; Kedar and Webb 2005). They arise from atmospheric energy converted to (primarily) Rayleigh waves via the intermediary of wind-driven oceanic swell and occupy a period band that is uninfluenced by common anthropogenic and wind-coupled noise processes on land (Wilson et al. 2002; de la Torre et al. 2005). "Primary" microseisms (near 8-s period) are generated in shallow water by breaking waves near the shore and/or the nonlinear interaction of the ocean wave pressure signal with the sloping sea floor (Hasselmann 1963). Secondary microseisms occur at half of the primary period and are especially strongly radiated in source regions where opposing wave components interfere (Longuett-Higgins 1950; Tanimoto 2007), which principally occurs due to the interaction of incident swell and reflected/scattered wave energy from coasts (Bromirski and Duennebier 2002; Bromirski, Duennebier, and Stephen 2005). Coastal regions having a narrow shelf with irregular and rocky coastlines are known to be especially efficient at radiating secondary microseisms (Bromirski, Duennebier, and Stephen 2005; Shulte-Pelkum et al. 2004). The secondary microseism is globally dominant, and its amplitudes proportional to the square of the standing wave height (Longuett-Higgins 1950), which amplifies its sensitivity to large swell events (Astiz and Creager 1994; Webb 2006).

  9. Microseism and infrasound generation by cyclones.

    PubMed

    Bowen, Samuel P; Richard, Jacques C; Mancini, Jay D; Fessatidis, Vassilios; Crooker, Benjamin

    2003-05-01

    A two-dimensional cylindrical shear-flow wave theory for the generation of microseisms and infrasound by hurricanes and cyclones is developed as a linearized theory paralleling the seminal work by Longuet-Higgins which was limited to one-dimensional plane waves. Both theories are based on Bernoulli's principle. A little appreciated consequence of the Bernoulli principle is that surface gravity waves induce a time dependent pressure on the sea floor through a vertical column of water. A significant difference exists between microseisms detected at the bottom of each column and seismic signals radiated into the crust through coherence over a region of the sea floor. The dominant measured frequency of radiated microseisms is matched by this new theory for seismic data gathered at the Fordham Seismic Station both for a hurricane and a mid-latitude cyclone in 1998. Implications for Bernoulli's principle and this cylindrical stress flow theory on observations in the literature are also discussed. PMID:12765375

  10. Electrolytic plating apparatus for discrete microsized particles

    DOEpatents

    Mayer, Anton

    1976-11-30

    Method and apparatus are disclosed for electrolytically producing very uniform coatings of a desired material on discrete microsized particles. Agglomeration or bridging of the particles during the deposition process is prevented by imparting a sufficiently random motion to the particles that they are not in contact with a powered cathode for a time sufficient for such to occur.

  11. Electroless plating apparatus for discrete microsized particles

    DOEpatents

    Mayer, Anton

    1978-01-01

    Method and apparatus are disclosed for producing very uniform coatings of a desired material on discrete microsized particles by electroless techniques. Agglomeration or bridging of the particles during the deposition process is prevented by imparting a sufficiently random motion to the particles that they are not in contact with each other for a time sufficient for such to occur.

  12. Hydrodynamic glide efficiency in swimming.

    PubMed

    Naemi, Roozbeh; Easson, William J; Sanders, Ross H

    2010-07-01

    The glide is a major part of starts, turns and the stroke cycle in breaststroke. Glide performance, indicated by the average velocity, can be improved by increasing the glide efficiency, that is, the ability of the body to minimise deceleration. This paper reviews the factors that affect glide efficiency. In the first part of the review the sources of resistive force are reviewed including surface friction (skin drag), pressure (form) drag and resistance due to making waves (wave drag). The effect of body surface characteristics on the skin drag, the effect of the depth of the swimmer on wave drag, and the effects of posture and alignment, body size and shape on the form drag are reviewed. The effects of these variables on the added mass, that is, the mass of water entrained with the body are explained. The 'glide factor' as a measure of glide efficiency that takes into account the combined effect of the resistive force and the added mass is described. In the second part methods of quantifying the resistive force are reviewed. Finally, the 'hydro-kinematic method' of measuring glide efficiency is evaluated. PMID:19540161

  13. Locating Microseism Sources in Offshore Southern California

    NASA Astrophysics Data System (ADS)

    Tian, X.; Clayton, R. W.

    2007-12-01

    We use the broadband stations from the S. California network to locate the apparent origin of secondary microseisms energy (5-8 Hz band). The procedure is to grid the offshore region and using each grid point as the source point, predict the response of a Rayleigh wave at each station. These predicted waveforms are then correlated with the data over a time window that is typically a 1/2 hour in length and composited at the grid point. The length of the time window controls a tradeoff between the spatial-temporal resolution of the sources and the robustness on the image. The procedure is valid for multiple sources. This results show that during periods of high microseism activity the sources are distinct at several locations in a region approximately 50-100 km offshore. For an 11/09/2002 Southern Ocean storm, for example, two zones parallel to each other and perpendicular to the coast are imaged.

  14. Similarities and differences between gliding glow and gliding arc discharges

    NASA Astrophysics Data System (ADS)

    Kolev, St.; Bogaerts, A.

    2015-12-01

    In this work we have analyzed the properties of a gliding dc discharge in argon at atmospheric pressure. Despite the usual designation of these discharges as ‘gliding arc discharges’, it was found previously that they operate in two different regimes—glow and arc. Here we analyze the differences in both regimes by means of two dimensional fluid modeling. In order to address different aspects of the discharge operation, we use two models—Cartesian and axisymmetric in a cylindrical coordinate system. The obtained results show that the two types of discharges produce a similar plasma column for a similar discharge current. However, the different mechanisms of plasma channel attachment to the cathode could produce certain differences in the plasma parameters (i.e. arc elongation), and this can affect gas treatments applications.

  15. Characteristics of body wave microseism observed at northern continental Asia

    NASA Astrophysics Data System (ADS)

    Sheen, D. H.; Jung, S.

    2014-12-01

    It has been understood that most of microseism observed at land is generated at coastal region by the ocean wave activity and propagates into the continent as the Rayleigh wave. However, it has also been reported that microseism could be generated at mid ocean and propagate as the body waves, such as P, PP and PKP phases. In this study, we analyzed microseisms with seismic records from seismic stations that are located at northern continental Asia. These included seismic arrays and a local dense network at South Korea, Kazakhstan, and China. First, we computed seismic noise spectra in the frequency band between 0.01 and 0.4 Hz. Second, the back-azimuth and the phase velocity of the microseism were measured from the frequency-wavenumber (FK) analysis. Although each data set was recorded at different time periods, the results show similar patterns. Non-transient microseism peak around the 0.2 Hz frequency was observed coherently at all data of winter season. The FK analysis shows that this microseism propagated with the phase velocities of around 12, 11, and 21 km/s at South Korea, China, and Kazakhstan, respectively. The back-projection of the FK result shows that these body wave microseisms were mostly generated at the northern part of the Pacific.

  16. [Mechanism of bacterial gliding motility].

    PubMed

    Nakane, Daisuke

    2015-01-01

    Bacteria have various way to move over solid surfaces, such as glass, agar, and host cell. These movements involve surface appendages including flagella, type IV pili and other "mysterious" nano-machineries. Gliding motility was a term used various surface movements by several mechanisms that have not been well understood in past few decades. However, development of visualization techniques allowed us to make much progress on their dynamics of machineries. It also provided us better understanding how bacteria move over surfaces and why bacteria move in natural environments. In this review, I will introduce recent studies on the gliding motility of Flavobacteium and Mycoplasma based on the detail observation of single cell and its motility machinery with micro-nano scales. PMID:26632217

  17. Bacteria that glide with helical tracks

    PubMed Central

    Nan, Beiyan; McBride, Mark J.; Chen, Jing; Zusman, David R.; Oster, George

    2014-01-01

    Many bacteria glide smoothly on surfaces, but with no discernable propulsive organelles on their surface. Recent experiments with Myxococcus xanthus and Flavobacterium johnsoniae show that both distantly related bacterial species glide utilizing proteins that move in helical tracks, albeit with significantly different motility mechanisms. Both species utilize proton motive force for movement. However, the motors that power gliding in M. xanthus have been identified, while the F. johnsoniae motors remain to be discovered. PMID:24556443

  18. Micro-size polyacrylamide gel electrophoresis system

    NASA Astrophysics Data System (ADS)

    Hinson, W. G.; Pipkin, J. L.; Anson, J. F.; Casciano, D. A.; Burns, E. R.

    1987-09-01

    The development and characterization of a micro-size two-dimensional polyacrylamide gel electrophoresis system is described. Some of the techniques which have evolved with use of the system are also discussed. This apparatus has unique features which provide advantages over other small scale units. Up to ten first- and second-dimension gels can be processed simultaneously with excellent resolution of protein regions. Consistent reproducibility is possible from protein samples as small as 400 ng and individual protein regions as small as 1 pg can be visualized by silver staining of the two-dimensional gels. Similar sensitivities are achieved in autoradiographs of 3H-labeled proteins extracted from the nuclei of cultured cells. The application of this system in conjunction with flow cytometric examination of nuclear DNA and electrostatic cell sorting of specific cell nuclei to provide homogeneous sample populations, allows subtle variations in isotope incorporation in proteins to be detected; whereas many times in generalized tissue samples these changes are masked. Also, these techniques elucidate the effects of external stimuli (chemicals, drugs, or environment) on protein synthesis and phosphorylation for analyses and comparison. Fabrication drawings are available upon request.

  19. Radial gravitational gliding on passive margins

    NASA Astrophysics Data System (ADS)

    Cobbold, P. R.; Szatmari, P.

    1991-03-01

    Gravitational gliding of uppermost sediments down a passive margin is possible if there is a basal layer of evaporite or other soft material to allow detachment. In examples from the Gulf of Mexico and the Brazilian margin, gliding has produced three main structural domains: an uppermost domain of downdip extension; an intermediate domain of rigid gliding; and a lowermost domain of downdip contraction. Domain boundaries are established by changes in slope. In this paper, we examine three kinds of gravitational gliding, depending on the paths followed by material particles. In ideal parallel gliding, particle paths are parallel straight lines, trending downslope. This should occur where the margin is perfectly straight. In ideal radial gliding, particle paths are radii of a circle and the margin is shaped like a circular cone. Natural margins will not have ideal shapes; but divergent gliding will tend to occur off coastal salients; convergent gliding, off coastal re-entrants. A simple kinematic model based on ductile behaviour illustrates some essential features of radial gliding. Changes in radius during divergent gliding produce strike-parallel extension; during convergent gliding, they produce strike-parallel contraction. Vertical strains also differ. Divergent gliding produces an uppermost domain of strong vertical thinning, balanced by extensions in all horizontal directions. Similarly, convergent gliding produces a lowermost domain of strong vertical thickening, balanced by contractions in all horizontal directions. These deformed states cannot be restored by simple techniques based on section balancing. We have done three experiments using analogue materials: sand, to model the brittle behaviour of sediments; silicone putty, to model the ductile behaviour of basal layers of evaporite. The experiments were properly scaled to account for gravitational forces. Experiment I reproduced convergent gliding above a basement with a conical upper surface. Strike

  20. Glides and Phonological Change in Mombasan Swahili.

    ERIC Educational Resources Information Center

    Kelly, John

    1991-01-01

    A study of the pronunciation of an adult male Swahili speaker, a native and long-term resident of Mombasa Old Town, supplemented with notes on other adult speakers, suggests a new account of glides and phonological change in this variation of the language. The asymmetrical distribution of the two glide types (palatal and labiovelar) is analyzed…

  1. New model of flap-gliding flight.

    PubMed

    Sachs, Gottfried

    2015-07-21

    A new modelling approach is presented for describing flap-gliding flight in birds and the associated mechanical energy cost of travelling. The new approach is based on the difference in the drag characteristics between flapping and non-flapping due to the drag increase caused by flapping. Thus, the possibility of a gliding flight phase, as it exists in flap-gliding flight, yields a performance advantage resulting from the decrease in the drag when compared with continuous flapping flight. Introducing an appropriate non-dimensionalization for the mathematical relations describing flap-gliding flight, results and findings of generally valid nature are derived. It is shown that there is an energy saving of flap-gliding flight in the entire speed range compared to continuous flapping flight. The energy saving reaches the highest level in the lower speed region. The travelling speed of flap-gliding flight is composed of the weighted average of the differing speeds in the flapping and gliding phases. Furthermore, the maximum range performance achievable with flap-gliding flight and the associated optimal travelling speed are determined. PMID:25841702

  2. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus)

    PubMed Central

    Bahlman, Joseph W.; Swartz, Sharon M.; Riskin, Daniel K.; Breuer, Kenneth S.

    2013-01-01

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60–125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight. PMID:23256188

  3. Glide performance and aerodynamics of non-equilibrium glides in northern flying squirrels (Glaucomys sabrinus).

    PubMed

    Bahlman, Joseph W; Swartz, Sharon M; Riskin, Daniel K; Breuer, Kenneth S

    2013-03-01

    Gliding is an efficient form of travel found in every major group of terrestrial vertebrates. Gliding is often modelled in equilibrium, where aerodynamic forces exactly balance body weight resulting in constant velocity. Although the equilibrium model is relevant for long-distance gliding, such as soaring by birds, it may not be realistic for shorter distances between trees. To understand the aerodynamics of inter-tree gliding, we used direct observation and mathematical modelling. We used videography (60-125 fps) to track and reconstruct the three-dimensional trajectories of northern flying squirrels (Glaucomys sabrinus) in nature. From their trajectories, we calculated velocities, aerodynamic forces and force coefficients. We determined that flying squirrels do not glide at equilibrium, and instead demonstrate continuously changing velocities, forces and force coefficients, and generate more lift than needed to balance body weight. We compared observed glide performance with mathematical simulations that use constant force coefficients, a characteristic of equilibrium glides. Simulations with varying force coefficients, such as those of live squirrels, demonstrated better whole-glide performance compared with the theoretical equilibrium state. Using results from both the observed glides and the simulation, we describe the mechanics and execution of inter-tree glides, and then discuss how gliding behaviour may relate to the evolution of flapping flight. PMID:23256188

  4. Microseisms from the Great Salt Lake

    NASA Astrophysics Data System (ADS)

    Goddard, K. J.; Koper, K. D.; Burlacu, V.

    2014-12-01

    Dept. of Geology and Geophysics, University of Utah, Salt Lake City, UT, 84112, USA We performed frequency-dependent polarization and power analysis on continuous ambient seismic energy recorded by broadband seismic stations that were part of the Utah Regional Seismic Network (UU) for the years of 2001-2013. The number of broadband seismometers increased from 10 to 28 in this time period. As expected, at all 28 stations the single and double frequency peaks caused by microseisms were observed in the range of 3-20 s. At four of the stations located around the Great Salt Lake (BGU, HVU, NOQ, and SPU) an additional noise peak was intermittently observed in the period range of 0.8-1.2 s. This noise peak was strongest at SPU, a station located on the tip of a peninsula jutting into the lake from the north, and weakest at NOQ, a station located a few kilometers south of the lake in the Oquirrh Mountains. The noise peaks occur in both daytime and nighttime, and have durations lasting from a couple of hours to multiple days. They occur more frequently in the spring, summer, and fall, and less commonly in the winter. The occurrences of noise peaks in the summer show a day night pattern and seem to reach a peak during the night. The time dependence of this 1-s seismic noise was compared to records of wind speed measured at 1-hr intervals from nearby meteorological stations run by the NWS, and to lake level gage height measurements made by the USGS. Correlations with wind speed and lake level were done for every month of the year in 2013. Results showed that the correlations with wind varied throughout the year from a high of 0.49 in November to a low of 0.20 in the month of January. The correlation with lake level also varied throughout the year and the strongest correlation was found in the month of December with a correlation of 0.43. While these correlation values are statistically significant, neither wind nor lake level can completely explain the seismic observations

  5. 14 CFR 171.267 - Glide path automatic monitor system.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Glide path automatic monitor system. 171... Landing System (ISMLS) § 171.267 Glide path automatic monitor system. (a) The ISMLS glide path equipment... control points when any of the following occurs: (1) A shift of the mean ISMLS glide path angle...

  6. 14 CFR 171.267 - Glide path automatic monitor system.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Glide path automatic monitor system. 171... Landing System (ISMLS) § 171.267 Glide path automatic monitor system. (a) The ISMLS glide path equipment... control points when any of the following occurs: (1) A shift of the mean ISMLS glide path angle...

  7. 14 CFR 171.267 - Glide path automatic monitor system.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Glide path automatic monitor system. 171... Landing System (ISMLS) § 171.267 Glide path automatic monitor system. (a) The ISMLS glide path equipment... control points when any of the following occurs: (1) A shift of the mean ISMLS glide path angle...

  8. 14 CFR 171.267 - Glide path automatic monitor system.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Glide path automatic monitor system. 171... Landing System (ISMLS) § 171.267 Glide path automatic monitor system. (a) The ISMLS glide path equipment... control points when any of the following occurs: (1) A shift of the mean ISMLS glide path angle...

  9. 14 CFR 171.267 - Glide path automatic monitor system.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Glide path automatic monitor system. 171... Landing System (ISMLS) § 171.267 Glide path automatic monitor system. (a) The ISMLS glide path equipment... control points when any of the following occurs: (1) A shift of the mean ISMLS glide path angle...

  10. A Mesozoic gliding mammal from northeastern China.

    PubMed

    Meng, Jin; Hu, Yaoming; Wang, Yuanqing; Wang, Xiaolin; Li, Chuankui

    2006-12-14

    Gliding flight has independently evolved many times in vertebrates. Direct evidence of gliding is rare in fossil records and is unknown in mammals from the Mesozoic era. Here we report a new Mesozoic mammal from Inner Mongolia, China, that represents a previously unknown group characterized by a highly specialized insectivorous dentition and a sizable patagium (flying membrane) for gliding flight. The patagium is covered with dense hair and supported by an elongated tail and limbs; the latter also bear many features adapted for arboreal life. This discovery extends the earliest record of gliding flight for mammals to at least 70 million years earlier in geological history, and demonstrates that early mammals were diverse in their locomotor strategies and lifestyles; they had experimented with an aerial habit at about the same time as, if not earlier than, when birds endeavoured to exploit the sky. PMID:17167478

  11. Antibacterial activity of aquatic gliding bacteria.

    PubMed

    Sangnoi, Yutthapong; Anantapong, Theerasak; Kanjana-Opas, Akkharawit

    2016-01-01

    The study aimed to screen and isolate strains of freshwater aquatic gliding bacteria, and to investigate their antibacterial activity against seven common pathogenic bacteria. Submerged specimens were collected and isolated for aquatic gliding bacteria using four different isolation media (DW, MA, SAP2, and Vy/2). Gliding bacteria identification was performed by 16S rRNA gene sequencing and phylogenetic analysis. Crude extracts were obtained by methanol extraction. Antibacterial activity against seven pathogenic bacteria was examined by agar-well diffusion assay. Five strains of aquatic gliding bacteria including RPD001, RPD008, RPD018, RPD027 and RPD049 were isolated. Each submerged biofilm and plastic specimen provided two isolates of gliding bacteria, whereas plant debris gave only one isolate. Two strains of gliding bacteria were obtained from each DW and Vy/2 isolation medium, while one strain was obtained from the SAP2 medium. Gliding bacteria strains RPD001, RPD008 and RPD018 were identified as Flavobacterium anhuiense with 96, 82 and 96 % similarity, respectively. Strains RPD049 and RPD027 were identified as F. johnsoniae and Lysobacter brunescens, respectively, with similarity equal to 96 %. Only crude extract obtained from RPD001 inhibited growth of Listeria monocytogenes (MIC 150 µg/ml), Staphylococcus aureus (MIC 75 µg/ml) and Vibrio cholerae (MIC 300 µg/ml), but showed weak inhibitory effect on Salmonella typhimurium (MIC > 300 µg/ml). Gliding bacterium strain RPD008 should be considered to a novel genus separate from Flavobacterium due to its low similarity value. Crude extract produced by RPD001 showed potential for development as a broad antibiotic agent. PMID:26885469

  12. Micro-Sized Enterprises, Innovation and Universities: A Welsh Perspective

    ERIC Educational Resources Information Center

    Jones, Paul; Patz, Ralf; Thomas, Brychan; McCarthy, Simon

    2014-01-01

    This study considers the linkage between micro-sized enterprises and other organizations, especially universities, in relation to the innovation process. The focus of the research is on non-start-up enterprises in Wales and how they develop their products. The research methodology adopted is a thematic literature review and the case study…

  13. Approaches for the Detection of Microseism Generating Regions from Space

    NASA Astrophysics Data System (ADS)

    Rodriguez, E.; Kedar, S.

    2004-12-01

    Ocean microseisms have been suggested as a potential source for tomographic imaging of the Earth. An optimal tomographic approach requires that the source regions for ocean microseism generation be known. Longuet-Higgins (Philos. trans. R. Soc. London, 1950) has suggested that standing waves in the ocean are responsible for the generation of microseisms, so that a potential way of determining the regions responsible for microseism generation is the determination of which regions of the ocean exhibit standing wave activity. Although ocean standing waves have been observed and modeled in a laboratory setting, there is currently no remote sensing instrument capable of providing direct observations. In this paper, we consider remote sensing or modeling measurements which might provide observations indicative of potential standing wave activity. The first option, radar altimetry, provides a measurement of the significant wave height and, at lower resolutions, sea surface skewness. It is expected that non-linear interactions will result in a spatial modulation of the wave field and an increase of surface skewness. We review the accuracy of current ocean altimeters and conclude that, while these type of observations might be possible in the future, current altimeters do not have sufficient accuracy to retrieve the expected signals. An alternate approach is to use wave directional spectra to estimate the standing wave energy which might be observed. There are two potential sources for the estimation of directional wave spectra: wave action models (WAM's) or synthetic aperture radar (SAR). We review the capabilities of each of these measurements and conclude that they present a useful potential source for estimating regions of microseism generation. To test this conclusion, we present results of comparisons between SAR data collected off the California and WAM data with seismic data.

  14. Quantifying the influence of sea ice on ocean microseism using observations from the Bering Sea, Alaska

    USGS Publications Warehouse

    Tsai, Victor C.; McNamara, Daniel E.

    2011-01-01

    Microseism is potentially affected by all processes that alter ocean wave heights. Because strong sea ice prevents large ocean waves from forming, sea ice can therefore significantly affect microseism amplitudes. Here we show that this link between sea ice and microseism is not only a robust one but can be quantified. In particular, we show that 75–90% of the variability in microseism power in the Bering Sea can be predicted using a fairly crude model of microseism damping by sea ice. The success of this simple parameterization suggests that an even stronger link can be established between the mechanical strength of sea ice and microseism power, and that microseism can eventually be used to monitor the strength of sea ice, a quantity that is not as easily observed through other means.

  15. Identifying apparent velocity changes in cross correlated microseism noise data

    NASA Astrophysics Data System (ADS)

    Friderike Volk, Meike; Bean, Christopher; Lokmer, Ivan; Pérez, Nemesio; Ibáñez, Jesús

    2015-04-01

    Currently there is a strong interest of using cross correlation of ambient noise to retrieve Green's functions. These are usually used to calculate the seismic wave velocity of the subsurface and therefore can be used for subsurface imaging or monitoring of various geological settings where we expect rapid velocity changes (e.g. reservoirs or volcanoes). The assumption of this method is that the wavefields which are correlated must be diffuse. This criterion is fulfilled if the ambient noise sources are uniformly distributed or the scattering in the medium is high enough to mitigate any source directivity. The location of the sources is usually unknown and it can change in time. These temporal and spatial variations of the microseism noise sources may lead to changes in the retrieved Green's functions, and so, to the apparent changes in seismic wave velocities. To further investigate the apparent changes in Green's functions we undertook an active seismic experiment in Tenerife lasting three months. A small airgun was used as an active source and was shooting repeatedly every 15 minutes. The shots and the microseism noise were recorded at several seismic stations at the same time. That data set gives us the opportunity to compare the changes in seismic wave velocity recovered through cross correlation of ambient noise and changes we measure through active shots from the airgun. The aim is to distinguish between apparent seismic velocity changes and seismic velocity changes caused by changes in the medium. We also use the data set to track the direction of the microseism noise sources to see if changes which are only recovered through cross correlation can be related to temporal and spatial variations of the microseism noise sources.

  16. Synthesis of micro-sized interconnected Si-C composites

    DOEpatents

    Wang, Donghai; Yi, Ran; Dai, Fang

    2016-02-23

    Embodiments provide a method of producing micro-sized Si--C composites or doped Si--C and Si alloy-C with interconnected nanoscle Si and C building blocks through converting commercially available SiO.sub.x (0

  17. Ray-theoretical modeling of secondary microseism P-waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-06-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P-waves that propagate in water down to the ocean bottom where they are partly reflected, and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P-waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P-waves in the ocean, (3) the propagation from the ocean bottom to the stations, (4) the receiver site effect. Secondary microseism P-waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analyzing the seismic signals generated by Typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Back projecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  18. Ray-theoretical modeling of secondary microseism P waves

    NASA Astrophysics Data System (ADS)

    Farra, V.; Stutzmann, E.; Gualtieri, L.; Schimmel, M.; Ardhuin, F.

    2016-09-01

    Secondary microseism sources are pressure fluctuations close to the ocean surface. They generate acoustic P waves that propagate in water down to the ocean bottom where they are partly reflected and partly transmitted into the crust to continue their propagation through the Earth. We present the theory for computing the displacement power spectral density of secondary microseism P waves recorded by receivers in the far field. In the frequency domain, the P-wave displacement can be modeled as the product of (1) the pressure source, (2) the source site effect that accounts for the constructive interference of multiply reflected P waves in the ocean, (3) the propagation from the ocean bottom to the stations and (4) the receiver site effect. Secondary microseism P waves have weak amplitudes, but they can be investigated by beamforming analysis. We validate our approach by analysing the seismic signals generated by typhoon Ioke (2006) and recorded by the Southern California Seismic Network. Backprojecting the beam onto the ocean surface enables to follow the source motion. The observed beam centroid is in the vicinity of the pressure source derived from the ocean wave model WAVEWATCH IIIR. The pressure source is then used for modeling the beam and a good agreement is obtained between measured and modeled beam amplitude variation over time. This modeling approach can be used to invert P-wave noise data and retrieve the source intensity and lateral extent.

  19. Characteristics of microseisms recorded by the Earthscope Transportable Array

    NASA Astrophysics Data System (ADS)

    Sufri, Oner

    I analyzed the characteristics of microseisms recorded in the United States by Earthscope Transportable Array (TA) broadband stations during the calendar year of 2009 and a 19-day period of October-November 2012. I used eigen-decomposition of spectral covariance matrices to extract power and polarization information for each hour of data recorded at each seismometer. For the continuous data from 2009, I generated array-averaged spectrograms and geographical animations to locate individual microseisms. Then, I grouped and cataloged those microseisms according to their initiation time, duration, peak power, average power, dominant period, variation in their period content, degree of polarization, and their azimuths obtained from polarization ellipsoids. Over 78 distinct microseismic events were identified and grouped into four different types. The longest duration microseismic signal occurred in the month of December, 2009, for more than 280 hours and was associated with the propagation of two storms: one from the Gulf of Alaska region and another from the Newfoundland region. The most powerful signal was also recorded in the same month with an average peak period near 6-sec on December 28-31, 2009, and resulted from wave action associated with two different unnamed storms in the East-Central Pacific and North Atlantic oceans. The seismic observations were compared to excitation predictions computed with the power spectral density of the equivalent pressure generated by ocean gravity waves using the WAVEWATCH-III ocean wave model from the French Research Institute for Exploitation of the Sea (Ifremer). Microseismic excitation predictions were calculated both with and without coastline reflections. I also processed continuous TA seismic data from 17 October-4 November, 2012, coinciding with the passage of Hurricane Sandy. I determined and tracked locations of microseisms as the hurricane propagated from South to North along the U.S. Atlantic coast. I found that the

  20. Performance analysis of jump-gliding locomotion for miniature robotics.

    PubMed

    Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M

    2015-04-01

    Recent work suggests that jumping locomotion in combination with a gliding phase can be used as an effective mobility principle in robotics. Compared to pure jumping without a gliding phase, the potential benefits of hybrid jump-gliding locomotion includes the ability to extend the distance travelled and reduce the potentially damaging impact forces upon landing. This publication evaluates the performance of jump-gliding locomotion and provides models for the analysis of the relevant dynamics of flight. It also defines a jump-gliding envelope that encompasses the range that can be achieved with jump-gliding robots and that can be used to evaluate the performance and improvement potential of jump-gliding robots. We present first a planar dynamic model and then a simplified closed form model, which allow for quantification of the distance travelled and the impact energy on landing. In order to validate the prediction of these models, we validate the model with experiments using a novel jump-gliding robot, named the 'EPFL jump-glider'. It has a mass of 16.5 g and is able to perform jumps from elevated positions, perform steered gliding flight, land safely and traverse on the ground by repetitive jumping. The experiments indicate that the developed jump-gliding model fits very well with the measured flight data using the EPFL jump-glider, confirming the benefits of jump-gliding locomotion to mobile robotics. The jump-glide envelope considerations indicate that the EPFL jump-glider, when traversing from a 2 m height, reaches 74.3% of optimal jump-gliding distance compared to pure jumping without a gliding phase which only reaches 33.4% of the optimal jump-gliding distance. Methods of further improving flight performance based on the models and inspiration from biological systems are presented providing mechanical design pathways to future jump-gliding robot designs. PMID:25811417

  1. Temporal evolution characteristics of an annular-mode gliding arc discharge in a vortex flow

    SciTech Connect

    Zhao, Tian-Liang; Liu, Jing-Lin; Li, Xiao-Song; Liu, Jin-Bao; Song, Yuan-Hong; Xu, Yong; Zhu, Ai-Min

    2014-05-15

    An annular-mode gliding arc discharge powered by a 50 Hz alternating current (ac) supply was studied in a vortex flow of dry and humid air. Its temporal evolution characteristics were investigated by electrical measurement, temporally resolved imaging, and temporally resolved optical emission spectroscopic measurements. Three discharge stages of arc-ignition, arc-gliding, and arc-extinction were clearly observed in each half-cycle of the discharge. During the arc-gliding stage, the intensity of light emission from the arc root at the cathode was remarkably higher than that at other areas. The spectral intensity of N{sub 2}(C{sup 3}Π{sub u}−B{sup 3}Π{sub g}) during the arc-ignition stage was much higher than that during the arc-gliding stage, which was contrary to the temporal evolutions of spectral intensities for N{sub 2}{sup +}(B{sup 2}Σ{sub u}{sup +}−X{sup 2}Σ{sub g}{sup +}) and OH(A{sup 2}Σ{sup +}−X{sup 2}Π{sub i}). Temporally resolved vibrational and rotational temperatures of N{sub 2} were also presented and decreased with increasing the water vapor content.

  2. 14 CFR 171.265 - Glide path performance requirements.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Glide path performance requirements. 171... Landing System (ISMLS) § 171.265 Glide path performance requirements. This section prescribes the performance requirements for glide path equipment components of the ISMLS. These requirements are based on...

  3. Aerodynamic Characteristics and Glide-Back Performance of Langley Glide-Back Booster

    NASA Technical Reports Server (NTRS)

    Pamadi, Bandu N.; Covell, Peter F.; Tartabini, Paul V.; Murphy, Kelly J.

    2004-01-01

    NASA-Langley Research Center is conducting system level studies on an-house concept of a small launch vehicle to address NASA's needs for rapid deployment of small payloads to Low Earth Orbit. The vehicle concept is a three-stage system with a reusable first stage and expendable upper stages. The reusable first stage booster, which glides back to launch site after staging around Mach 3 is named the Langley Glide-Back Booster (LGBB). This paper discusses the aerodynamic characteristics of the LGBB from subsonic to supersonic speeds, development of the aerodynamic database and application of this database to evaluate the glide back performance of the LGBB. The aerodynamic database was assembled using a combination of wind tunnel test data and engineering level analysis. The glide back performance of the LGBB was evaluated using a trajectory optimization code and subject to constraints on angle of attack, dynamic pressure and normal acceleration.

  4. Investigation of gliding flight by flying fish

    NASA Astrophysics Data System (ADS)

    Park, Hyungmin; Jeon, Woo-Pyung; Choi, Haecheon

    2006-11-01

    The most successful flight capability of fish is observed in the flying fish. Furthermore, despite the difference between two medium (air and water), the flying fish is well evolved to have an excellent gliding performance as well as fast swimming capability. In this study, flying fish's morphological adaptation to gliding flight is experimentally investigated using dry-mounted darkedged-wing flying fish, Cypselurus Hiraii. Specifically, we examine the effects of the pectoral and pelvic fins on the aerodynamic performance considering (i) both pectoral and pelvic fins, (ii) pectoral fins only, and (iii) body only with both fins folded. Varying the attack angle, we measure the lift, drag and pitching moment at the free-stream velocity of 12m/s for each case. Case (i) has higher lift-to-drag ratio (i.e. longer gliding distance) and more enhanced longitudinal static stability than case (ii). However, the lift coefficient is smaller for case (i) than for case (ii), indicating that the pelvic fins are not so beneficial for wing loading. The gliding performance of flying fish is compared with those of other fliers and is found to be similar to those of insects such as the butterfly and fruitfly.

  5. Novel mechanisms power bacterial gliding motility.

    PubMed

    Nan, Beiyan; Zusman, David R

    2016-07-01

    For many bacteria, motility is essential for survival, growth, virulence, biofilm formation and intra/interspecies interactions. Since natural environments differ, bacteria have evolved remarkable motility systems to adapt, including swimming in aqueous media, and swarming, twitching and gliding on solid and semi-solid surfaces. Although tremendous advances have been achieved in understanding swimming and swarming motilities powered by flagella, and twitching motility powered by Type IV pili, little is known about gliding motility. Bacterial gliders are a heterogeneous group containing diverse bacteria that utilize surface motilities that do not depend on traditional flagella or pili, but are powered by mechanisms that are less well understood. Recently, advances in our understanding of the molecular machineries for several gliding bacteria revealed the roles of modified ion channels, secretion systems and unique machinery for surface movements. These novel mechanisms provide rich source materials for studying the function and evolution of complex microbial nanomachines. In this review, we summarize recent findings made on the gliding mechanisms of the myxobacteria, flavobacteria and mycoplasmas. PMID:27028358

  6. Remote, real-time monitoring of cyclones with microseisms

    NASA Astrophysics Data System (ADS)

    Jo, B. G.; Lee, W. D.; Schwab, F. A.

    2014-12-01

    Giving proper care to selecting microseisms from well isolated cyclones, these great oceanic storms can be monitored in real time by seismic recordings at stations 1200-4100 km distant from the cyclone's center. We treat ocean depths of 3.4-5.5 km. For the theoretically-computed microseism, which our procedure compares with the experimental data, we use a Green's-function approach in the frequency domain. Relating recorded displacement F and theoretical Green's function G, We have F(ω,r)=S(ω)G(ω,r) in which our only unknown is the generalized source function S(ω) and r is the distance to the center at any specific time. The basic result of this report is that the form of this function is A SN(ω), where A is a real constant increasing with the strength of the cyclone and SN(ω), is a positive real function of frequency, independent of cyclone-receiver separation and of cyclone strength. That is, for a given ocean basin, and a given receiver-region geology, at our current level of accuracy SN(ω) is the same for all cyclone strengths and cyclone-receiver separations. Using the multimode approach, we've developed the numerical method for computing the Green's function for multilayered oceanic structures. For each of the 4 selected cyclones, the source functions for all locations along the path show a consistency which demonstrates that the recorded microseisms are radiated from the cyclone. The extracted source function exhibits spectra that are characteristic of ocean waves generated by cyclonic winds. With knowledge of distance between the source and receiver, cyclone A is therefore trivial to monitor in real time from remote recordings. At the current time, the cyclone's strength—generalized source function—must be related empirically to the cyclone's maximum wind speed, areal extent, and lateral velocity.

  7. Uncovering the Mystery of Gliding Motility in the Myxobacteria

    PubMed Central

    Nan, Beiyan; Zusman, David R.

    2012-01-01

    Bacterial gliding motility is the smooth movement of cells on solid surfaces unaided by flagella or pili. Many diverse groups of bacteria exhibit gliding, but the mechanism of gliding motility has remained a mystery since it was first observed more than a century ago. Recent studies on the motility of Myxococcus xanthus, a soil myxobacterium, suggest a likely mechanism for gliding in this organism. About forty M. xanthus genes were shown to be involved in gliding motility, and some of their protein products were labeled and localized within cells. These studies suggest that gliding motility in M. xanthus involves large multiprotein structural complexes, regulatory proteins, and cytoskeletal filaments. In this review, we summarize recent experiments that provide the basis for this emerging view of M. xanthus motility. We also discuss alternative models for gliding. PMID:21910630

  8. Mapping the source distribution of microseisms using noise covariogram envelopes

    NASA Astrophysics Data System (ADS)

    Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Roberts, Roland; Tryggvason, Ari

    2016-06-01

    We introduce a method for mapping the noise-source distribution of microseisms which uses information from the full length of covariograms (cross-correlations). We derive a forward calculation based on the plane-wave assumption in 2-D, to formulate an iterative, linearized inversion of covariogram envelopes in the time domain. The forward calculation involves bandpass filtering of the covariograms. The inversion exploits the well-known feature of noise cross-correlation, that is, an anomaly in the noise field that is oblique to the interstation direction appears as cross-correlation amplitude at a smaller time lag than the in-line, surface wave arrival. Therefore, the inversion extracts more information from the covariograms than that contained at the expected surface wave arrival, and this allows us to work with few stations to find the propagation directions of incoming energy. The inversion is naturally applied to data that retain physical units that are not amplitude normalized in any way. By dividing a network into groups of stations, we can constrain the source location by triangulation. We demonstrate results of the method with synthetic data and one year (2012) of data from the Swedish National Seismic Network and also look at the seasonal variation of source distribution around Scandinavia. After preprocessing and cross-correlation, the stations are divided into five groups of 9-12 stations. We invert the envelopes of each group in eight period ranges between 2 and 25 s. Results show that the noise sources at short periods (less than 12 s) lie predominantly in the North Atlantic Ocean and the Barents Sea, and at longer periods the energy appears to have a broader distribution. The strongly anisotropic source distribution in this area is estimated to cause significant biases of velocity measurements compared to the level of heterogeneity in the region. The amplitude of the primary microseisms varies little over the year, but secondary microseisms are much

  9. Insights Into the Origin of Earth's hum and Microseisms

    NASA Astrophysics Data System (ADS)

    Romanowicz, B. A.; Rhie, J.; Colas, B.

    2005-12-01

    We have recently documented that the sources of Earth's background free oscillations in the 2-7 mHz frequency range, are primarily in the oceans. We used array data from two regional networks of VBB seismometers, in California (Berkeley Digital Seismic Network) and in Japan (F-NET). We proposed a mechanism for their generation, involving the coupling of infragravity waves with the ocean floor, where the infragravity waves would be produced through non-linear interactions between storm generated ocean waves. The precise mechanism of this atmosphere-ocean-seafloor coupling is however not yet well understood, as well as their relation to microseisms, another type of seismic noise originating from ocean waves, which dominates seismic records in the period range 0.1-1 Hz. In order to gain further insight into these intriguing phenomena, we have focused on the North Pacific region, where the dominant sources of hum appear to be located in the northern hemisphere winter. We have assembled a dataset of significant wave height recordings at buoys deployed by the National Oceanographic Atmospheric Administration (NOAA) and Japan Meteorological Agency (JMA) for a five day period in 2000, during which two large storms develop and propagate across the Pacific, there are no significant earthquakes, and the background "hum" is maximum. From the temporal correlations between the signature of the storms on the buoy data and the seismic low frequency Rayleigh wave background noise, we infer that the coupling with the seafloor most likely occurs near the coast, around the rim of the north Pacific ocean. We also show that we can track the generated Rayleigh waves as they propagate from West to East across the continental United States. We have also assembled and processed 3 years of microseism data at stations of the BDSN, F-NET arrays, and show a strong correlation of amplitude fluctations in the microseismic band with that in the "hum" band during the northern hemispheric winter

  10. Mapping the source distribution of microseisms using noise covariogram envelopes

    NASA Astrophysics Data System (ADS)

    Sadeghisorkhani, Hamzeh; Gudmundsson, Ólafur; Roberts, Roland; Tryggvason, Ari

    2016-03-01

    We introduce a method for mapping the noise-source distribution of microseisms which uses information from the full length of covariograms (cross-correlations). We derive a forward calculation based on the plane-wave assumption in 2D, to formulate an iterative, linearized inversion of covariogram envelopes in the time domain. The forward calculation involves bandpass filtering of the covariograms. The inversion exploits the well-known feature of noise cross-correlation, i.e., that an anomaly in the noise field that is oblique to the inter-station direction appears as cross-correlation amplitude at a smaller time lag than the in-line, surface-wave arrival. Therefore, the inversion extracts more information from the covariograms than that contained at the expected surface-wave arrival, and this allows us to work with few stations to find the propagation directions of incoming energy. The inversion is naturally applied to data that retain physical units, i.e., that are not amplitude normalized in any way. By dividing a network into groups of stations, we can constrain the source location by triangulation. We demonstrate results of the method with synthetic data and one year (2012) of data from the Swedish National Seismic Network (SNSN) and also look at the seasonal variation of source distribution around Scandinavia. After preprocessing and cross-correlation, the stations are divided into 5 groups of 9 to 12 stations. We invert the envelopes of each group in 8 period ranges between 2 to 25 sec. Results show that the noise sources at short periods (less than 12 sec) lie predominantly in the North Atlantic Ocean and the Barents Sea, and at longer periods the energy appears to have a broader distribution. The strongly anisotropic source distribution in this area is estimated to cause significant biases of velocity measurements compared to the level of heterogeneity in the region. The amplitude of the primary microseisms varies little over the year, but secondary

  11. Typhoon-induced Microseisms Recorded Offshore and Onland Western Pacific Regions

    NASA Astrophysics Data System (ADS)

    Chen, W.; Chi, W.; Dolenc, D.; Kuo, B.; Lin, C.; Collins, J. A.

    2008-12-01

    Microseisms usually are generated by continuous forcing of winds and ocean waves in shallow water, with the frequency controlled by the fetch area. Here we study microseisms during extreme weather conditions. In 2006 we deployed the first broadband ocean bottom seismometers (OBSs) offshore Taiwan. The OBSs at 1749 meters and 4726 meters water depths recorded strong microseisms signals (0.02 to 1 Hz passband) when Shan-Shan typhoon passed over the OBSs. This provides a unique opportunity to study how the microseisms wavefield evolves with a moving source. We studied the displacement waveforms recorded by OBSs, F-net and GSN onland stations. The spectrograms show primary peak energy between 0.05 to 0.1 Hz, and the stronger secondary peak appeared between 0.1 and 0.2 Hz. The primary peak has longer duration than the secondary peak. The arrival time of the peak typhoon-induced displacement for each station is consistently earlier than the time when the eye of typhoon gets closest to the station. We also see the microseisms ground motion energy migrating from south to north, and its primary energy frequency does not correlate with fetch areas. In sum, we have recorded strong microseisms motions in deep water, and the frequency band of the strong microseisms may not change with different fetch areas. Besides, the moving typhoon lits up the seismic stations along the track, showing clear evidence of a moving microseism source region.

  12. On complex, curved trajectories in microtubule gliding

    NASA Astrophysics Data System (ADS)

    Gosselin, Pierre; Mohrbach, Hervé; Kulić, Igor M.; Ziebert, Falko

    2016-04-01

    We study the dynamics of microtubules in gliding assays. These biofilaments are typically considered as purely semiflexible, hence their trajectories under the action of motors covering the substrate have been regarded so far as straight, modulo fluctuations. However, this is not always the case experimentally, where microtubules are known to move on large scale circles or spirals, or even display quite regular wavy trajectories and more complex dynamics. Incorporating recent experimental evidence for a (small) preferred curvature as well as the microtubules' well established lattice twist into a dynamic model for microtubule gliding, we could reproduce both types of trajectories. Interestingly, as a function of the microtubules' length we found length intervals of stable rings alternating with regions where wavy and more complex dynamics prevails. Finally, both types of dynamics (rings and waves) can be rationalized by considering simple limits of the full model.

  13. Origin of deep ocean microseisms by using teleseismic body waves

    NASA Astrophysics Data System (ADS)

    LandèS, Matthieu; Hubans, Fabien; Shapiro, Nikolai M.; Paul, Anne; Campillo, Michel

    2010-05-01

    Recent studies of oceanic microseisms have concentrated on fundamental mode surface waves. Extraction of fundamental mode Rayleigh and Love wave Green functions from station-station correlations of ambient seismic noise has recently been demonstrated to be a very powerful tool for imaging of the Earth's crust and uppermost mantle. In this study we concentrate on energetic arrivals in two frequency bands around the primary (14 s) and the secondary (7 s) microseismic peaks that appear at near-zero times in noise cross correlations. Thanks to a polarization analysis of data from the Eastern Turkey Seismic Experiment network, we identify this "near-zero time" signal as an upcoming P wave in the secondary microseismic frequency band (5-10 s). In a second step, analyzing noise cross correlations from three different arrays (in Yellowstone, in Turkey, and in Kyrgyzstan), we determine the origin of these signals by means of beam-forming analysis and its projection on the Earth. Our results show that in the 0.1-0.3 Hz frequency band, the energetic "near-zero" time arrivals in seismic noise cross correlations are mainly formed by teleseismic P, PP, and PKP waves. Generation of this ambient body waves in the secondary microseismic band presents a marked seasonal behavior with sources located in southern and northern oceans during summer and winter, respectively. Moreover, body wave array analysis is accurate enough to confirm that significant amount of the microseism energy is generated far from the coast in deep oceans.

  14. Assessing the importance of terrain parameters on glide avalanche release

    USGS Publications Warehouse

    Peitzsch, Erich H.; Hendrikx, Jordy; Fagre, Daniel B.

    2014-01-01

    Glide snow avalanches are dangerous and difficult to predict. Despite recent research there is still a lack of understanding regarding the controls of glide avalanche release. Glide avalanches often occur in similar terrain or the same locations annually and observations suggest that topography may be critical. Thus, to gain an understanding of the terrain component of these types of avalanches we examined terrain parameters associated with glide avalanche release as well as areas of consistent glide crack formation but no subsequent avalanches. Glide avalanche occurrences visible from the Going-to-the-Sun Road corridor in Glacier National Park, Montana from 2003-2013 were investigated using an avalanche database derived of daily observations each year from April 1 to June 15. This yielded 192 glide avalanches in 53 distinct avalanche paths. Each avalanche occurrence was digitized in a GIS using satellite, oblique, and aerial imagery as reference. Topographical parameters such as area, slope, aspect, elevation and elevation were then derived for the entire dataset utilizing GIS tools and a 10m DEM. Land surface substrate and surface geology were derived from National Park Service Inventory and Monitoring maps and U.S. Geological Survey surface geology maps, respectively. Surface roughness and glide factor were calculated using a four level classification index. . Then, each avalanche occurrence was aggregated to general avalanche release zones and the frequencies were compared. For this study, glide avalanches released in elevations ranging from 1300 to 2700 m with a mean aspect of 98 degrees (east) and a mean slope angle of 38 degrees. The mean profile curvature for all glide avalanches was 0.15 and a plan curvature of -0.01, suggesting a fairly linear surface (i.e. neither convex nor concave). The glide avalanches occurred in mostly bedrock made up of dolomite and limestone slabs and talus deposits with very few occurring in alpine meadows. However, not all glide

  15. LEDS theory of workhardening stages and planar versus distributed glide

    NASA Astrophysics Data System (ADS)

    Kuhlmann-Wilsdorf, D.; Wilsdorf, H. G. F.; Wert, J. A.

    1994-09-01

    From a widespread convention, glide in crystalline materials is classified as 'planar' versus 'distributed'. At elevated temperatures, 'distributed glide' is favored and is almost usually found at medium to high strains in pure metals, in low-concentration homogeneous alloys, and in a preponderance of multiphase alloys, provided temperatures are not too low. While at low temperatures, 'planar glide' is widely observed and favored in solid solution alloys. In this paper, a general explanation is presented over the proposed additional causes for planar versus distributed glide, based on the LEDS theory.

  16. A source representation of microseisms constrained by HV spectral ratio observations

    NASA Astrophysics Data System (ADS)

    Dreger, D.; Rhie, J.

    2006-12-01

    The microseisms are generated by pressure variation on the sea floor caused by incident and reflected ocean waves, and dominant background noises at short periods. The observations of microseism wave fields in deep sedimentary basins (e.g., Santa Clara Valley) show that the maximum period of the horizontal to vertical (H/V) spectral ratio correlates with basin thickness. A similar correlation has been found in teleseismic arrival times and P-wave amplitude as well as local-earthquake S-wave relative amplification [Dolenc et al., 2005]. This observation infers that a study of microseism wave field, combined with other seismic data sets, can probably be used to invert for the velocity structures of the deep basins. To make this inversion possible, it is necessary to understand the excitation and propagation characteristics of microseisms. We will perform forward computations of microseism wave fields for source representations such as CLVDs and single-forces with the USGS 3D velocity model. Various spatial extensions as well as the frequency content of the source will be tested to match observed shifts in dominant H/V spectral ratio. The optimal source representation of the microseisms will be the first step to accomplish inversions for 3D seismic velocity structure in sedimentary basins using microseisms.

  17. Micro-size optical fibre strain interrogation system

    NASA Astrophysics Data System (ADS)

    Mrad, Nezih; Xiao, Gaozhi; Guo, Honglei

    2008-03-01

    Within several countries, the military is undergoing significant economic pressure to extend the use of its air fleet beyond its established design life. The availability of low weight, small size, reliable and cost-effective technologies to detect and monitor incipient damage and to alert prior to catastrophic failures is critical to sustain operational effectiveness. To enable the implementation of distributed and highly multiplexed optical fiber sensors networks to aerospace platforms, the data acquisition (interrogation) system has to meet small size and low weight requirements. This paper reports on our current development of micro-sized Echelle Diffractive Gratings (EDG) based interrogation system for strain monitoring of serially multiplexed fibre Bragg grating sensors. The operation principle of the interrogator and its suitability for strain measurements is demonstrated. Static load measurements obtained using this system are compared to those acquired using a optical multi-wavelength meter and are found to have strong correlation.

  18. A numerical investigation on the properties of the modal Green's functions of microseisms

    NASA Astrophysics Data System (ADS)

    Jo, B. G.; Lee, W.; Fred, S.; Kim, J.; Jung, S.

    2011-12-01

    Theoretical spectrum of microseisms was introduced in our previous study, which indicates that the main peaks of the theoretical microseisms retained roughly at the same frequency as those of observed microseisms, and consist of almost full range of higher modes. In this study, we carried out a systematic investigation to find the fundamental properties that affect the features of microseisms by (1) presenting the associated sampling behavior of seismic modes comprising microseisms, and (2) showing the effect of earth structure and propagation on the microseisms. The sampling behavior of the seismic modes, being a function of frequency and mode number, were investigated with rigorous computations of the energy-density function from mode 1 to mode 70, for the period range of 2~20 sec., which is the typical frequency range of microseisms. All the mode parameters are calculated for the oceanic model with vertical point source at the top of the liquid layer. In the energy density function of each modes commonly shows that the depth of maximum energy of each mode migrates to the shallower structure as the frequency increases. However, the sampling depths are found to jump up to the uppermost liquid layer abruptly at around 0.08 Hz (about T= 12.6 sec) for all the modes, except mode 1, as a result, a steep amplitude depression is developed in the computed displacement spectra at around the frequency. Thus, the amplitude spectra of the computed microseisms, the sum of amplitude spectra of all modes, are devided into two parts, known as the primary and secondary microseism, with a boundary at around 0.08 Hz, which corresponds very well to the observed microseisms' amplitude spectra. Together with these overall features, three distinct classes of amplitude spectra are recognized, such as modes mainly contributing to the primary peaks, modes contributing mostly to the secondary peaks, and modes with substantial energies at both primary and secondary peaks. In general, the

  19. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Glide: Single-engine airplanes. 23.71... Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical miles... with the engine inoperative, its propeller in the minimum drag position, and landing gear and...

  20. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Glide: Single-engine airplanes. 23.71... Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical miles... with the engine inoperative, its propeller in the minimum drag position, and landing gear and...

  1. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Glide: Single-engine airplanes. 23.71... Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical miles... with the engine inoperative, its propeller in the minimum drag position, and landing gear and...

  2. 14 CFR 171.265 - Glide path performance requirements.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 3 2013-01-01 2013-01-01 false Glide path performance requirements. 171.265 Section 171.265 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED) NAVIGATIONAL FACILITIES NON-FEDERAL NAVIGATION FACILITIES Interim Standard Microwave Landing System (ISMLS) § 171.265 Glide...

  3. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Glide: Single-engine airplanes. 23.71... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Flight Performance § 23.71 Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical...

  4. 14 CFR 23.71 - Glide: Single-engine airplanes.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Glide: Single-engine airplanes. 23.71... Glide: Single-engine airplanes. The maximum horizontal distance traveled in still air, in nautical miles... with the engine inoperative, its propeller in the minimum drag position, and landing gear and...

  5. Gliding Motility of Mycoplasma mobile on Uniform Oligosaccharides

    PubMed Central

    Kasai, Taishi; Hamaguchi, Tasuku

    2015-01-01

    ABSTRACT The binding and gliding of Mycoplasma mobile on a plastic plate covered by 53 uniform oligosaccharides were analyzed. Mycoplasmas bound to and glided on only 21 of the fixed sialylated oligosaccharides (SOs), showing that sialic acid is essential as the binding target. The affinities were mostly consistent with our previous results on the inhibitory effects of free SOs and suggested that M. mobile recognizes SOs from the nonreducing end with four continuous sites as follows. (i and ii) A sialic acid at the nonreducing end is tightly recognized by tandemly connected two sites. (iii) The third site is recognized by a loose groove that may be affected by branches. (iv) The fourth site is recognized by a large groove that may be enhanced by branches, especially those with a negative charge. The cells glided on uniform SOs in manners apparently similar to those of the gliding on mixed SOs. The gliding speed was related inversely to the mycoplasma's affinity for SO, suggesting that the detaching step may be one of the speed determinants. The cells glided faster and with smaller fluctuations on the uniform SOs than on the mixtures, suggesting that the drag caused by the variation in SOs influences gliding behaviors. IMPORTANCE Mycoplasma is a group of bacteria generally parasitic to animals and plants. Some Mycoplasma species form a protrusion at a pole, bind to solid surfaces, and glide in the direction of the protrusion. These procedures are essential for parasitism. Usually, mycoplasmas glide on mixed sialylated oligosaccharides (SOs) derived from glycoprotein and glycolipid. Since gliding motility on uniform oligosaccharides has never been observed, this study gives critical information about recognition and interaction between receptors and SOs. PMID:26148712

  6. Uncertainty estimates in broadband seismometer sensitivities using microseisms

    NASA Astrophysics Data System (ADS)

    Ringler, A. T.; Storm, T.; Gee, L. S.; Hutt, C. R.; Wilson, D.

    2015-04-01

    The midband sensitivity of a seismic instrument is one of the fundamental parameters used in published station metadata. Any errors in this value can compromise amplitude estimates in otherwise high-quality data. To estimate an upper bound in the uncertainty of the midband sensitivity for modern broadband instruments, we compare daily microseism (4- to 8-s period) amplitude ratios between the vertical components of colocated broadband sensors across the IRIS/USGS (network code IU) seismic network. We find that the mean of the 145,972 daily ratios used between 2002 and 2013 is 0.9895 with a standard deviation of 0.0231. This suggests that the ratio between instruments shows a small bias and considerable scatter. We also find that these ratios follow a standard normal distribution ( R 2 = 0.95442), which suggests that the midband sensitivity of an instrument has an error of no greater than ±6 % with a 99 % confidence interval. This gives an upper bound on the precision to which we know the sensitivity of a fielded instrument.

  7. Uncertainty estimates in broadband seismometer sensitivities using microseisms

    USGS Publications Warehouse

    Ringler, Adam T.; Storm, Tyler L.; Gee, Lind S.; Hutt, Charles R.; Wilson, David C.

    2015-01-01

    The midband sensitivity of a seismic instrument is one of the fundamental parameters used in published station metadata. Any errors in this value can compromise amplitude estimates in otherwise high-quality data. To estimate an upper bound in the uncertainty of the midband sensitivity for modern broadband instruments, we compare daily microseism (4- to 8-s period) amplitude ratios between the vertical components of colocated broadband sensors across the IRIS/USGS (network code IU) seismic network. We find that the mean of the 145,972 daily ratios used between 2002 and 2013 is 0.9895 with a standard deviation of 0.0231. This suggests that the ratio between instruments shows a small bias and considerable scatter. We also find that these ratios follow a standard normal distribution (R 2 = 0.95442), which suggests that the midband sensitivity of an instrument has an error of no greater than ±6 % with a 99 % confidence interval. This gives an upper bound on the precision to which we know the sensitivity of a fielded instrument.

  8. Degradation of Verapamil hydrochloride in water by gliding arc discharge.

    PubMed

    Krishna, Syam; Maslani, Alan; Izdebski, Tomasz; Horakova, Marta; Klementova, Sarka; Spatenka, Petr

    2016-06-01

    This study investigated the influence of gliding arc plasma discharge on the degradation of Verapamil hydrochloride in water. The plasma discharge was characterized by means of optical emission spectroscopy. Spectra of various atomic and molecular species were observed. Aqueous solution of Verapamil hydrochloride was exposed to gliding arc discharge operated in continuous discharge at atmospheric pressure and room temperature. The identification of Verapamil, the degradation mechanisms of Verapamil and its transformation products were performed using liquid chromatography - mass spectrometry (HPLC-MS). Experimental results indicate that the atmospheric pressure gliding arc plasma treatment has noticeable effects on Verapamil with satisfactory degradation efficiency. Plausible mechanisms of the degradation were discussed. PMID:26953731

  9. An Efficient Implementation of the Gliding Box Lacunarity Algorithm

    SciTech Connect

    Charles R. Tolle,; Timothy R. McJunkin; David J. Gorsich

    2008-03-01

    Lacunarity is a measure of how data fills space. It complements fractal dimension, which measures how much space is filled. Currently, many researchers use the gliding box algorithm for calculating lacunarity. This paper introduces a fast algorithm for making this calculation. The algorithm presented is akin to fast box counting algorithms used by some researchers in estimating fractal dimension. A simplified gliding box measure equation along with key pseudo code implementations for the algorithm are presented. Applications for the gliding box lacunarity measure have included subjects that range from biological community modeling to target detection.

  10. Unitary step of gliding machinery in Mycoplasma mobile

    PubMed Central

    Kinosita, Yoshiaki; Nakane, Daisuke; Sugawa, Mitsuhiro; Masaike, Tomoko; Mizutani, Kana; Miyata, Makoto; Nishizaka, Takayuki

    2014-01-01

    Among the bacteria that glide on substrate surfaces, Mycoplasma mobile is one of the fastest, exhibiting smooth movement with a speed of 2.0–4.5 μm⋅s−1 with a cycle of attachment to and detachment from sialylated oligosaccharides. To study the gliding mechanism at the molecular level, we applied an assay with a fluorescently labeled and membrane-permeabilized ghost model, and investigated the motility by high precision colocalization microscopy. Under conditions designed to reduce the number of motor interactions on a randomly oriented substrate, ghosts took unitary 70-nm steps in the direction of gliding. Although it remains possible that the stepping behavior is produced by multiple interactions, our data suggest that these steps are produced by a unitary gliding machine that need not move between sites arranged on a cytoskeletal lattice. PMID:24912194

  11. Substrate-induced gliding in a nematic liquid crystal layer

    NASA Astrophysics Data System (ADS)

    Mema, E.; Kondic, L.; Cummings, L. J.

    2015-12-01

    We consider the interaction between nematic liquid crystals (NLCs) and polymer substrates. Such substrates can interact with NLCs, exhibiting a phenomenon known as director gliding: the preferred orientation of the NLC molecules at the interface changes on time scales that are slow relative to the elastic relaxation time scale of the NLC. We present two models for gliding, inspired by experiments that investigate the interaction between the NLC and a polymer substrate. These models, though simple, lead to nontrivial results, including loss of bistability under gliding. Perhaps surprisingly, we find that externally imposed switching between the steady states of a bistable system may reverse the effect of gliding, preventing loss of bistability if switching is sufficiently frequent. Our findings may be of relevance to a variety of technological applications involving liquid crystal devices, and particularly to a new generation of flexible liquid crystal displays that implement polymeric substrates.

  12. Substrate-induced gliding in a nematic liquid crystal layer.

    PubMed

    Mema, E; Kondic, L; Cummings, L J

    2015-12-01

    We consider the interaction between nematic liquid crystals (NLCs) and polymer substrates. Such substrates can interact with NLCs, exhibiting a phenomenon known as director gliding: the preferred orientation of the NLC molecules at the interface changes on time scales that are slow relative to the elastic relaxation time scale of the NLC. We present two models for gliding, inspired by experiments that investigate the interaction between the NLC and a polymer substrate. These models, though simple, lead to nontrivial results, including loss of bistability under gliding. Perhaps surprisingly, we find that externally imposed switching between the steady states of a bistable system may reverse the effect of gliding, preventing loss of bistability if switching is sufficiently frequent. Our findings may be of relevance to a variety of technological applications involving liquid crystal devices, and particularly to a new generation of flexible liquid crystal displays that implement polymeric substrates. PMID:26764717

  13. Soaring energetics and glide performance in a moving atmosphere.

    PubMed

    Taylor, Graham K; Reynolds, Kate V; Thomas, Adrian L R

    2016-09-26

    Here, we analyse the energetics, performance and optimization of flight in a moving atmosphere. We begin by deriving a succinct expression describing all of the mechanical energy flows associated with gliding, dynamic soaring and thermal soaring, which we use to explore the optimization of gliding in an arbitrary wind. We use this optimization to revisit the classical theory of the glide polar, which we expand upon in two significant ways. First, we compare the predictions of the glide polar for different species under the various published models. Second, we derive a glide optimization chart that maps every combination of headwind and updraft speed to the unique combination of airspeed and inertial sink rate at which the aerodynamic cost of transport is expected to be minimized. With these theoretical tools in hand, we test their predictions using empirical data collected from a captive steppe eagle (Aquila nipalensis) carrying an inertial measurement unit, global positioning system, barometer and pitot tube. We show that the bird adjusts airspeed in relation to headwind speed as expected if it were seeking to minimize its aerodynamic cost of transport, but find only weak evidence to suggest that it adjusts airspeed similarly in response to updrafts during straight and interthermal glides.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. PMID:27528788

  14. Electrical charging of skis gliding on snow.

    PubMed

    Colbeck, S C

    1995-01-01

    Ski charging was measured using giant-slalom style skis as gliding capacitors. The voltage measured across the plates was proportional to the charge on the base. While resting on dry snow or suspended in the air, the voltage was slowly reduced by the data logger itself. On wet snow the decay was much faster. While stationary on powder snow the ski developed a slightly negative voltage, showed a small, transient positive peak when motion began, rapidly dropped to negative values, and then assumed a quasi-steady climb to positive voltages. A great deal of noise was superimposed on the general features of the signal when skiing on hard or bumpy surfaces. Thus, the accumulation of charge to high levels was only possible with long runs in deep powder. The rate of charging increased with speed but was not affected by use of one "antistatic" wax, and another such wax actually increased the measured voltage over that of an unwaxed base. PMID:7898330

  15. Identification and Characterization of Several Large Hurricanes using Microseisms

    NASA Astrophysics Data System (ADS)

    Ebeling, C. W.; Stein, S. A.; Moore, C.

    2010-12-01

    An ongoing debate within the climatological community centers on whether rising North Atlantic sea-surface temperatures due to anthropogenic global warming are changing the frequency or energy of hurricanes. A short and incomplete observational record makes it difficult to answer this question. Since North Atlantic hurricane records were based entirely on ship logs and land observations before aircraft reconnaissance began in 1944, it is possible that hurricanes may have gone unobserved before then. Even after the initiation of regular aircraft observation, not all areas were monitored. Hence the potential for sampling problems exists up until the advent of satellite-based observation in the mid-1960’s, implying that an undercount in the historical record is likely. To address this issue, we continue to develop methodology to improve the record of the number of North Atlantic hurricanes through the analysis of their signals recorded on decades of historical seismograms. Ambient seismic noise—signals derived from natural sources not related to earthquakes—is generated by atmospheric energy and so has been used as a proxy for oceanic wave climate and an indication of decadal-scale climate variability. Hence ambient seismic noise should be usable to detect hurricanes that may have gone unobserved. Our methodology towards a general hurricane discriminant uses digital data from the HRV (Harvard, Massachusetts) and SJG (San Juan, Puerto Rico) seismic stations to calibrate seismic noise signals correlated with maximum wind speeds of several well-characterized North Atlantic hurricanes. We find that filtering of HRV data recorded during hurricane Andrew (August 1992) in the 200-143 mHz passband retrieves a signal correlatable with Andrew’s maximum wind speed. Spectral amplitudes show that the energy in the secondary microseism band contains increasing low-frequency content as Andrew matures. Results based on this methodology for several additional large hurricanes

  16. Gliding Motility in Bacteria: Insights from Studies of Myxococcus xanthus

    PubMed Central

    Spormann, Alfred M.

    1999-01-01

    Gliding motility is observed in a large variety of phylogenetically unrelated bacteria. Gliding provides a means for microbes to travel in environments with a low water content, such as might be found in biofilms, microbial mats, and soil. Gliding is defined as the movement of a cell on a surface in the direction of the long axis of the cell. Because this definition is operational and not mechanistic, the underlying molecular motor(s) may be quite different in diverse microbes. In fact, studies on the gliding bacterium Myxococcus xanthus suggest that two independent gliding machineries, encoded by two multigene systems, operate in this microorganism. One machinery, which allows individual cells to glide on a surface, independent of whether the cells are moving alone or in groups, requires the function of the genes of the A-motility system. More than 37 A-motility genes are known to be required for this form of movement. Depending on an additional phenotype, these genes are divided into two subclasses, the agl and cgl genes. Videomicroscopic studies on gliding movement, as well as ultrastructural observations of two myxobacteria, suggest that the A-system motor may consist of multiple single motor elements that are arrayed along the entire cell body. Each motor element is proposed to be localized to the periplasmic space and to be anchored to the peptidoglycan layer. The force to glide which may be generated here is coupled to adhesion sites that move freely in the outer membrane. These adhesion sites provide a specific contact with the substratum. Based on single-cell observations, similar models have been proposed to operate in the unrelated gliding bacteria Flavobacterium johnsoniae (formerly Cytophaga johnsonae), Cytophaga strain U67, and Flexibacter polymorphus (a filamentous glider). Although this model has not been verified experimentally, M. xanthus seems to be the ideal organism with which to test it, given the genetic tools available. The second gliding

  17. Microsized structures assisted nanostructure formation on ZnSe wafer by femtosecond laser irradiation

    SciTech Connect

    Wang, Shutong; Feng, Guoying E-mail: zhoush@scu.edu.cn

    2014-12-22

    Micro/nano patterning of ZnSe wafer is demonstrated by femtosecond laser irradiation through a diffracting pinhole. The irradiation results obtained at fluences above the ablation threshold are characterized by scanning electron microscopy. The microsized structure with low spatial frequency has a good agreement with Fresnel diffraction theory. Laser induced periodic surface structures and laser-induced periodic curvelet surface structures with high spatial frequency have been found on the surfaces of microsized structures, such as spikes and valleys. We interpret its formation in terms of the interference between the reflected laser field on the surface of the valley and the incident laser pulse.

  18. GLobal Integrated Design Environment (GLIDE): A Concurrent Engineering Application

    NASA Technical Reports Server (NTRS)

    McGuire, Melissa L.; Kunkel, Matthew R.; Smith, David A.

    2010-01-01

    The GLobal Integrated Design Environment (GLIDE) is a client-server software application purpose-built to mitigate issues associated with real time data sharing in concurrent engineering environments and to facilitate discipline-to-discipline interaction between multiple engineers and researchers. GLIDE is implemented in multiple programming languages utilizing standardized web protocols to enable secure parameter data sharing between engineers and researchers across the Internet in closed and/or widely distributed working environments. A well defined, HyperText Transfer Protocol (HTTP) based Application Programming Interface (API) to the GLIDE client/server environment enables users to interact with GLIDE, and each other, within common and familiar tools. One such common tool, Microsoft Excel (Microsoft Corporation), paired with its add-in API for GLIDE, is discussed in this paper. The top-level examples given demonstrate how this interface improves the efficiency of the design process of a concurrent engineering study while reducing potential errors associated with manually sharing information between study participants.

  19. Glide-Shuffle Competition in Silicon: An Atomistic Study

    NASA Astrophysics Data System (ADS)

    Li, Ju; Cai, Wei; Chang, Jinpeng; Yip, Sidney

    2001-06-01

    Glide-Shuffle Competition in Silicon: An Atomistic Study Ju Li, Wei Cai, Jinpeng Chang, Sidney Yip, Massachusetts Institute of Technology, Department of Nuclear Engineering, Cambridge, MA 02139 Recent experiments by Suzuki et al and Rabier et al suggest that low-T and high-T plasticity in Si and III-IV compounds may be governed by different mechanisms. We perform direct atomistic calculations to obtain the core energies, Peierls-Nabarro stresses, and kink formation and migration energies of full shuffle- and glide-set dislocations and glide-set partial dislocations in Si using the Stillinger-Weber potential. These results are compared with previous calculations, and their implications will be discussed. Dynamical simulations of some of the full dislocations in motion show qualitatively different behavior with their counterparts in bcc metals.

  20. Prospects for the gliding mechanism of Mycoplasma mobile.

    PubMed

    Miyata, Makoto; Hamaguchi, Tasuku

    2016-02-01

    Mycoplasma mobile forms gliding machinery at a cell pole and glides continuously in the direction of the cell pole at up to 4.5μm per second on solid surfaces such as animal cells. This motility system is not related to those of any other bacteria or eukaryotes. M. mobile uses ATP energy to repeatedly catch, pull, and release sialylated oligosaccharides on host cells with its approximately 50-nm long legs. The gliding machinery is a large structure composed of huge surface proteins and internal jellyfish-like structure. This system may have developed from an accidental combination between an adhesin and a rotary ATPase, both of which are essential for the adhesive parasitic life of Mycoplasmas. PMID:26500189

  1. Global oceanic microseism sources as seen by seismic arrays and predicted by wave action models

    NASA Astrophysics Data System (ADS)

    Hillers, G.; Graham, N.; Landes, M.; Hubans, F.; Campillo, M.; Shapiro, N. M.; Paul, A.; Kedar, S.; Clayton, R. W.

    2010-12-01

    Estimated locations of P-wave microseism generation obtained from seismic arrays analyses are combined with ocean wave-wave interaction models to improve the understanding of microseism generation. Source regions of likely microseism generation are found by combining data from three different networks located in the northern hemisphere. For each array, teleseismic P-wave arrivals are extracted from station-station correlations of ambient noise associated with the secondary microseism peak. Estimates of the slowness and azimuth of the teleseismic body waves are obtained and source location probabilities are constructed by projecting these beamforming results to patches on the Earth's surface that represent likely source regions. The application of Longuet-Higgins' (LH) microseism excitation theory to hindcast ocean wave-wave interaction spectra combined with bathymetry has shown that microseism can be excited very locally in the deep oceans as a consequence of nonlinear atmosphere-ocean-seafloor interactions. We utilize this approach to identify the source mechanism and location associated with the body wave arrivals, and compare projection results from seismic array processing to predictions from globally distributed ocean wave-wave interaction intensities. Based on this technique we observe a number of previously undocumented potential source regions, such as the oceans south of Madagascar, or the southern tip of Australia. We find that spatial patterns of strong excitation generally agrees with the inferred source projections based on 12-day averaging noise correlations. Details of the distributions depend, however, on averaging choices applied to the 3-hourly sampled oceanic excitation functions. We therefore focus on the sensitivity and stability of the resulting spatio temporal correlations to choices of averaging, considering the mapping of temporally variable excitations into results of the array beamforming analysis. More specifically, we investigate to

  2. Improved Detection and Location of Ocean Microseism Signals using Array Techniques

    NASA Astrophysics Data System (ADS)

    Reading, A. M.; Gal, M.; Koper, K. D.; Tkalcic, H.

    2015-12-01

    We present and evaluate a range of approaches that may be used to investigate ocean microseisms using seismic array data. At amplitudes below the dominant incoming signal, the ambient seismic energy (background noise) associated with microseisms arrives from multiple directions at any one time. Thus we address the challenge of detecting weaker signals from unpredictable directions in the presence of other strong signals. Our aim is to extract the most accurate information possible from such weaker signals in order to expand the capability of ocean storm studies, using seismology, including the ability to extract storm patterns from archive seismic array records. Detection of weaker microseism signals may be improved using algorithms widely used in astronomy. One example is the CLEAN algorithm which has wide usage in radio astronomy. This algorithm operates by finding the position and strength of point sources and iteratively deconvolving their contribution to the image. It may be combined to optimum effect with the previously published (Incoherently Averaged Signal) IAS Capon implementation for an accurate detection of weaker sources. Having detected weaker sources, they may be backprojected using a suitable Earth model, taking into account a correction for the mislocation due to slowness-azimuth station corrections. The microseism generation locations inferred in this manner are strongly frequency dependent, even within relatively restricted frequency ranges (0.325-0.725 Hz) for some arrays. Our advances in seismic array processing, with a focus on methods appropriate to weaker ambient noise signals, have led to insights, for example, regarding the generation of seismic noise. We find that secondary microseisms in the lower frequency band are generated mainly by ocean swell whereas higher frequency bands are generated by local wind conditions. These arrivals are investigated over a two-decade time frame for the Southern Ocean and west Pacific Ocean.

  3. A methodology for boost-glide transport technology planning

    NASA Technical Reports Server (NTRS)

    Repic, E. M.; Olson, G. A.; Milliken, R. J.

    1974-01-01

    A systematic procedure is presented by which the relative economic value of technology factors affecting design, configuration, and operation of boost-glide transport can be evaluated. Use of the methodology results in identification of first-order economic gains potentially achievable by projected advances in each of the definable, hypersonic technologies. Starting with a baseline vehicle, the formulas, procedures and forms which are integral parts of this methodology are developed. A demonstration of the methodology is presented for one specific boost-glide system.

  4. Directionality of ambient noise on the Juan de Fuca plate: implications for source locations of the primary and secondary microseisms

    NASA Astrophysics Data System (ADS)

    Tian, Ye; Ritzwoller, Michael H.

    2015-04-01

    Based on cross-correlations of ambient seismic noise computed using 61 ocean bottom seismometers (OBSs) within the Juan de Fuca (JdF) plate from the Cascadia Initiative experiment and 42 continental stations near the coast of the western United States, we investigate the locations of generation of the primary (11-20 s period) and secondary (5-10 s period) microseisms in the northern Pacific Ocean by analysing the directionality and seasonality of the microseism (Rayleigh wave) signals received in this region. We conclude that (1) the ambient noise observed across the array is much different in the primary and secondary microseism bands, both in its azimuthal content and seasonal variation. (2) The principal secondary microseism signals propagate towards the east, consistent with their generation in deep waters of the North Pacific, perhaps coincident both with the region of observed body wave excitation and the predicted wave-wave interaction region from recent studies. (3) The primary microseism, as indicated by observations of the azimuthal dependence of the fundamental mode Rayleigh wave as well as observations of precursory arrivals, derives significantly from the shallow waters of the eastern Pacific near to the JdF plate but also has a component generated at greater distance of unknown origin. (4) These observations suggest different physical mechanisms for generating the two microseisms: the secondary microseisms are likely to be generated by non-linear wave-wave interaction over the deep Pacific Ocean, while the primary microseism may couple directly into the solid earth locally in shallow waters from ocean gravity waves. (5) Above 5 s period, high quality empirical Green's functions are observed from cross-correlations between deep water OBSs and continental stations, which illustrates that microseisms propagate efficiently from either deep or shallow water source regions onto the continent and are well recorded by continental seismic stations.

  5. The descent of ant: field-measured performance of gliding ants.

    PubMed

    Munk, Yonatan; Yanoviak, Stephen P; Koehl, M A R; Dudley, Robert

    2015-05-01

    Gliding ants avoid predatory attacks and potentially mortal consequences of dislodgement from rainforest canopy substrates by directing their aerial descent towards nearby tree trunks. The ecologically relevant measure of performance for gliding ants is the ratio of net horizontal to vertical distance traveled over the course of a gliding trajectory, or glide index. To study variation in glide index, we measured three-dimensional trajectories of Cephalotes atratus ants gliding in natural rainforest habitats. We determined that righting phase duration, glide angle, and path directness all significantly influence variation in glide index. Unsuccessful landing attempts result in the ant bouncing off its target and being forced to make a second landing attempt. Our results indicate that ants are not passive gliders and that they exert active control over the aerodynamic forces they experience during their descent, despite their apparent lack of specialized control surfaces. PMID:25788722

  6. Illusory Continuity without Sufficient Sound Energy to Fill a Temporal Gap: Examples of Crossing Glide Tones

    ERIC Educational Resources Information Center

    Kuroda, Tsuyoshi; Nakajima, Yoshitaka; Eguchi, Shuntarou

    2012-01-01

    The gap transfer illusion is an auditory illusion where a temporal gap inserted in a longer glide tone is perceived as if it were in a crossing shorter glide tone. Psychophysical and phenomenological experiments were conducted to examine the effects of sound-pressure-level (SPL) differences between crossing glides on the occurrence of the gap…

  7. Gliding Swifts Attain Laminar Flow over Rough Wings

    PubMed Central

    Lentink, David; de Kat, Roeland

    2014-01-01

    Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1–2% of chord length on the upper surface—10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13%) of their total area during glides that maximize flight distance and duration—similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation) before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance. PMID:24964089

  8. Gliding swifts attain laminar flow over rough wings.

    PubMed

    Lentink, David; de Kat, Roeland

    2014-01-01

    Swifts are among the most aerodynamically refined gliding birds. However, the overlapping vanes and protruding shafts of their primary feathers make swift wings remarkably rough for their size. Wing roughness height is 1-2% of chord length on the upper surface--10,000 times rougher than sailplane wings. Sailplanes depend on extreme wing smoothness to increase the area of laminar flow on the wing surface and minimize drag for extended glides. To understand why the swift does not rely on smooth wings, we used a stethoscope to map laminar flow over preserved wings in a low-turbulence wind tunnel. By combining laminar area, lift, and drag measurements, we show that average area of laminar flow on swift wings is 69% (n = 3; std 13%) of their total area during glides that maximize flight distance and duration--similar to high-performance sailplanes. Our aerodynamic analysis indicates that swifts attain laminar flow over their rough wings because their wing size is comparable to the distance the air travels (after a roughness-induced perturbation) before it transitions from laminar to turbulent. To interpret the function of swift wing roughness, we simulated its effect on smooth model wings using physical models. This manipulation shows that laminar flow is reduced and drag increased at high speeds. At the speeds at which swifts cruise, however, swift-like roughness prolongs laminar flow and reduces drag. This feature gives small birds with rudimentary wings an edge during the evolution of glide performance. PMID:24964089

  9. Dynamics of discrete screw dislocations on glide directions

    NASA Astrophysics Data System (ADS)

    Alicandro, R.; De Luca, L.; Garroni, A.; Ponsiglione, M.

    2016-07-01

    We consider a simple discrete model for screw dislocations in crystals. Using a variational discrete scheme we study the motion of a configuration of dislocations toward low energy configurations. We deduce an effective fully overdamped dynamics that follows the maximal dissipation criterion introduced in Cermelli and Gurtin (1999) and predicts motion along the glide directions of the crystal.

  10. 14 CFR 171.265 - Glide path performance requirements.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 3 2012-01-01 2012-01-01 false Glide path performance requirements. 171.265 Section 171.265 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Amplitude (DDM) (95 pct. probability) Outer limit of coverage to ISMLS point “C.” 0.035. The...

  11. 14 CFR 171.265 - Glide path performance requirements.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 3 2011-01-01 2011-01-01 false Glide path performance requirements. 171.265 Section 171.265 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Amplitude (DDM) (95 pct. probability) Outer limit of coverage to ISMLS point “C.” 0.035. The...

  12. 14 CFR 171.265 - Glide path performance requirements.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 3 2014-01-01 2014-01-01 false Glide path performance requirements. 171.265 Section 171.265 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF... Amplitude (DDM) (95 pct. probability) Outer limit of coverage to ISMLS point “C.” 0.035. The...

  13. Kick, Glide, Pole! Cross-Country Skiing Fun (Part II)

    ERIC Educational Resources Information Center

    Duoos, Bridget A.

    2012-01-01

    Part I of Kick, Glide, Pole! Cross-Country Skiing Fun, which was published in last issue, discussed how to select cross-country ski equipment, dress for the activity and the biomechanics of the diagonal stride. Part II focuses on teaching the diagonal stride technique and begins with a progression of indoor activities. Incorporating this fun,…

  14. Evaluation of snow-glide risk by modelling and on-site assessment

    NASA Astrophysics Data System (ADS)

    Leitinger, Georg; Meusburger, Katrin; Rüdisser, Johannes; Tasser, Erich; Höller, Peter

    2015-04-01

    Abandonment of agricultural practices on alpine grasslands lead to increasing snow-glide intensities due to lower surface roughness of the vegetation. Beneath the danger of snow-glide avalanches snow gliding leads to soil erosion and damaging of young trees at afforested sites. Especially in high altitudes afforestation is important to protect settlements and infrastructure against snow-gliding and glide avalanches. Snow-glide damages are therefore of particular danger for these afforestation sites. In the light of future climate change and warmer winter periods, studies already state increasing snow-glide risk and the occurrence of glide avalanches. This study presents an approach to evaluate snow-glide risk by combining the refined Spatial Snow Glide Model (SSGM) first published by Leitinger et al. (2008) and the Guidelines to Identify Snow-Glide Areas (GISGA) proposed by Höller (2012), an on-site risk analyses approach. First, GISGA was validated on the basis of corresponding snow-glide measurements. Second, a potential snow-glide map for an area in the Eastern Alps covering 20000 km² was modelled. The results revealed considerable areas of high snow-glide risk. Using the average amount of winter precipitation between 1990 and 2010 in the SSGM shows higher vulnerability for the northern part of the study area (Tyrol, Austria) than in the southern part (South Tyrol, Italy) because of lower winter precipitation. However, running the SSGM based on the highest winter precipitation registered in the study area between 1801 and 2003 exhibits the possibility of very high snow-glide risk for most parts of the study area with significant increasing risk in the southern part. Given the very probable future climate during winter periods with increasing temperatures but uncertain development of precipitation patterns, snow-glide activity and linked glide avalanches might further increase at least in areas and altitudes with solid precipitation. In combination with the

  15. Properies of the microseism wave field in Australia from three component array data

    NASA Astrophysics Data System (ADS)

    Gal, Martin; Reading, Anya; Ellingsen, Simon; Koper, Keith; Burlacu, Relu; Tkalčić, Hrvoje

    2016-04-01

    In the last two decades, ambient noise studies in the range of 1-20 seconds have predominantly focused on the analysis of source regions for Rayleigh and P waves. The theoretical excitation of these phases is well understood for primary microseisms (direct coupling of gravity waves in sloping shallow bathymetry) and secondary microseisms (wave-wave interaction) and correlates well with observations. For Love waves, the excitation mechanism in the secondary microseism band is to date unknown. It has been shown, that LQ waves can exhibit larger amplitudes than Rg waves for certain frequencies. Therefore detailed analysis of the wave field are necessary to find indications on the generation mechanism. We analyse data from two spiral-shaped arrays located in Australia, the Pilbara Array (PSAR) in the North-West and an array in South Queensland (SQspa) in the East. The two arrays are different in aperture and allow for the study of primary and secondary microseisms with SQspa and higher secondary microseisms with PSAR. We use a deconvolution enhanced beamforming approach, which is based on the CLEAN algorithm. It allows the accurate detection of weaker sources and the estimation of power levels on each component or wave type. For PSAR we evaluate 1 year of data in the frequency range of 0.35-1 Hz and find fundamental and higher mode Rg and LQ waves. For the low end of the frequency range, we find the strongest fundamental mode Rg waves to originate from multiple direction, but confined to coastline reflectors, i.e. coastlines that are perpendicular to the main swell direction, while higher mode Rg waves are mainly generated in the Great Australian Bight. For higher frequencies, the source locations of Rg waves move toward the north coast, which is closest to the array and we see an increase in the Lg phase. The majority of fundamental LQ waves are generated at the west coast of Australia and we find some agreement between low frequency Rg and LQ source locations, which

  16. Adaptive glide slope control for parafoil and payload aircraft

    NASA Astrophysics Data System (ADS)

    Ward, Michael

    Airdrop systems provide a unique capability of delivering large payloads to undeveloped and inaccessible locations. Traditionally, these systems have been unguided, requiring large landing zones and drops from low altitude. The invention of the steerable, gliding, ram-air parafoil enabled the possibility of precision aerial payload delivery. In practice, the gliding ability of the ram-air parafoil can actually create major problems for airdrop systems by making them more susceptible to winds and allowing them to achieve far greater miss distances than were previously possible. Research and development work on guided airdrop systems has focused primarily on evolutionary improvements to the guidance algorithm, while the navigation and control algorithms have changed little since the initial autnomous systems were developed. Furthermore, the control mechanisms have not changed since the invention of the ram-air canopy in the 1960’s. The primary contributions of this dissertation are: (1) the development of a reliable and robust method to identify a flight dynamic model for a parafoil and payload aircraft using minimal sensor data; (2) the first demonstration in flight test of the ability to achieve large changes in glide slope over ground using coupled incidence angle variation and trailing edge brake deflection; (3) the first development of a control law to implement glide slope control on an autonomous system; (4) the first flight tests of autonomous landing with a glide slope control mechanism demonstrating an improvement in landing accuracy by a factor of 2 or more in especially windy conditions, and (5) the first demonstrations in both simulation and flight test of the ability to perform in-flight system identification to adapt the internal control mappings to flight data and provide dramatic improvements in landing accuracy when there is a significant discrepancy between the assumed and actual flight characteristics.

  17. The enigma of eugregarine epicytic folds: where gliding motility originates?

    PubMed Central

    2013-01-01

    Background In the past decades, many studies focused on the cell motility of apicomplexan invasive stages as they represent a potential target for chemotherapeutic intervention. Gregarines (Conoidasida, Gregarinasina) are a heterogeneous group that parasitize invertebrates and urochordates, and are thought to be an early branching lineage of Apicomplexa. As characteristic of apicomplexan zoites, gregarines are covered by a complicated pellicle, consisting of the plasma membrane and the closely apposed inner membrane complex, which is associated with a number of cytoskeletal elements. The cell cortex of eugregarines, the epicyte, is more complicated than that of other apicomplexans, as it forms various superficial structures. Results The epicyte of the eugregarines, Gregarina cuneata, G. polymorpha and G. steini, analysed in the present study is organised in longitudinal folds covering the entire cell. In mature trophozoites and gamonts, each epicytic fold exhibits similar ectoplasmic structures and is built up from the plasma membrane, inner membrane complex, 12-nm filaments, rippled dense structures and basal lamina. In addition, rib-like myonemes and an ectoplasmic network are frequently observed. Under experimental conditions, eugregarines showed varied speeds and paths of simple linear gliding. In all three species, actin and myosin were associated with the pellicle, and this actomyosin complex appeared to be restricted to the lateral parts of the epicytic folds. Treatment of living gamonts with jasplakinolide and cytochalasin D confirmed that actin actively participates in gregarine gliding. Contributions to gliding of specific subcellular components are discussed. Conclusions Cell motility in gregarines and other apicomplexans share features in common, i.e. a three-layered pellicle, an actomyosin complex, and the polymerisation of actin during gliding. Although the general architecture and supramolecular organisation of the pellicle is not correlated with

  18. Microsized BiOCl Square Nanosheets as Ultraviolet Photodetectors and Photocatalysts.

    PubMed

    Li, Min; Zhang, Junying; Gao, Hong; Li, Feng; Lindquist, Sten-Eric; Wu, Nianqiang; Wang, Rongming

    2016-03-16

    BiOCl microstructures that include microspheres stacked by nanosheet and microsized square nanosheets, with a large lateral size of 3-5 μm and a thickness of 35 nm (the side length/thickness ratio is ∼100), are synthesized by a solvothermal method with the assistance of polyvinylpyrrolidone. The exposed face of the large square nanosheet is {001} facet. The BiOCl microstructures show good photocatalytic activity toward decomposition of Rhodamine B under ultraviolet-visible light irradiation. Moreover, individual microsized BiOCl square nanosheets are employed as the building block for construction of an ultraviolet photodetector. Because of its large size, thin thickness, and high surface-to-volume ratio, a BiOCl nanosheet shows high sensitivity and fast transient response to ultraviolet light in the spectral range 200-380 nm. PMID:26913647

  19. Are deep-ocean-generated surface-wave microseisms observed on land?

    NASA Astrophysics Data System (ADS)

    Bromirski, Peter D.; Stephen, Ralph A.; Gerstoft, Peter

    2013-07-01

    studies attribute land double-frequency (DF) microseism observations to deep water generation. Here we show that near-coastal generation is generally the dominant source region. This determination is based on observations at land and ocean seismic stations, buoys, gravity-wave hindcasts, and on beamforming results from continental seismic arrays. Interactions between opposing ocean wave components generate a pressure excitation pulse at twice the ocean wave frequency that excites pseudo-Rayleigh (pRg) wave DF microseisms. pRg generated in shallow coastal waters have most of their energy in the solid Earth ("elastic" pRg) and are observed by land-based and seafloor seismometers as DF microseisms. pRg generated in the deep ocean have most of their energy in the ocean ("acoustic" pRg) and are continuously observed on the ocean bottom, but acoustic pRg does not efficiently transition onto continents. High-amplitude DF signals over the [0.2, 0.3] Hz band observed on the deep seafloor are uncorrelated with continental observations and are not clearly detectable at individual continental stations or by land seismic-array beamforming. Below 0.2 Hz, modeling and some observations suggest that some deep water-generated elastic pRg energy can reach continental stations, providing that losses from scattering and transition across the continental-shelf boundary to the shore are not substantial. However, most observations indicate that generally little deep-ocean-generated DF microseism energy reaches continental stations. Effectively, DF land observations are dominated by near-coastal wave activity.

  20. Osteointegration of PLGA implants with nanostructured or microsized β-TCP particles in a minipig model.

    PubMed

    Kulkova, Julia; Moritz, Niko; Suokas, Esa O; Strandberg, Niko; Leino, Kari A; Laitio, Timo T; Aro, Hannu T

    2014-12-01

    Bioresorbable suture anchors and interference screws have certain benefits over equivalent titanium-alloy implants. However, there is a need for compositional improvement of currently used bioresorbable implants. We hypothesized that implants made of poly(l-lactide-co-glycolide) (PLGA) compounded with nanostructured particles of beta-tricalcium phosphate (β-TCP) would induce stronger osteointegration than implants made of PLGA compounded with microsized β-TCP particles. The experimental nanostructured self-reinforced PLGA (85L:15G)/β-TCP composite was made by high-energy ball-milling. Self-reinforced microsized PLGA (95L:5G)/β-TCP composite was prepared by melt-compounding. The composites were characterized by gas chromatography, Ubbelohde viscometry, scanning electron microscopy, laser diffractometry, and standard mechanical tests. Four groups of implants were prepared for the controlled laboratory study employing a minipig animal model. Implants in the first two groups were prepared from nanostructured and microsized PLGA/β-TCP composites respectively. Microroughened titanium-alloy (Ti6Al4V) implants served as positive intra-animal control, and pure PLGA implants as negative control. Cone-shaped implants were inserted in a random order unilaterally in the anterior cortex of the femoral shaft. Eight weeks after surgery, the mechanical strength of osteointegration of the implants was measured by a push-out test. The quality of new bone surrounding the implant was assessed by microcomputed tomography and histology. Implants made of nanostructured PLGA/β-TCP composite did not show improved mechanical osteointegration compared with the implants made of microsized PLGA/β-TCP composite. In the intra-animal comparison, the push-out force of two PLGA/β-TCP composites was 35-60% of that obtained with Ti6Al4V implants. The implant materials did not result in distinct differences in quality of new bone surrounding the implant. PMID:25241283

  1. The gliding speed of migrating birds: slow and safe or fast and risky?

    PubMed

    Horvitz, Nir; Sapir, Nir; Liechti, Felix; Avissar, Roni; Mahrer, Isaac; Nathan, Ran

    2014-06-01

    Aerodynamic theory postulates that gliding airspeed, a major flight performance component for soaring avian migrants, scales with bird size and wing morphology. We tested this prediction, and the role of gliding altitude and soaring conditions, using atmospheric simulations and radar tracks of 1346 birds from 12 species. Gliding airspeed did not scale with bird size and wing morphology, and unexpectedly converged to a narrow range. To explain this discrepancy, we propose that soaring-gliding birds adjust their gliding airspeed according to the risk of grounding or switching to costly flapping flight. Introducing the Risk Aversion Flight Index (RAFI, the ratio of actual to theoretical risk-averse gliding airspeed), we found that inter- and intraspecific variation in RAFI positively correlated with wing loading, and negatively correlated with convective thermal conditions and gliding altitude, respectively. We propose that risk-sensitive behaviour modulates the evolution (morphology) and ecology (response to environmental conditions) of bird soaring flight. PMID:24641086

  2. A comparison of glide force characteristics between 2 prefilled insulin lispro pens.

    PubMed

    Rees, Tina M; Lennartz, Amanda H; Ignaut, Debra A

    2015-03-01

    Glide force, average glide force, and glide force variability of the insulin lispro 200 units/mL pen (Eli Lilly and Company, Indianapolis, IN, USA) were compared to the Humalog KwikPen 100 units/mL pen (hereafter, KwikPen; Eli Lilly and Company, Indianapolis, IN, USA). Data were collected on 2 doses, 2 injection speeds, and 2 needle types. Insulin lispro 200 units/mL pen showed significantly lower maximum glide force, average glide force, and glide force variability than the KwikPen across all combinations of dose size, dose speed, and needle type. The lower glide force observed with the insulin lispro 200 units/mL pen offers another treatment option for patients with type 1 or type 2 diabetes who require greater than 20 units of mealtime insulin daily. PMID:25591858

  3. Observation of deep water microseisms in the North Atlantic Ocean using tide modulations

    NASA Astrophysics Data System (ADS)

    Beucler, Éric; Mocquet, Antoine; Schimmel, Martin; Chevrot, Sébastien; Quillard, Olivier; Vergne, Jérôme; Sylvander, Matthieu

    2015-01-01

    Ocean activity produces continuous and ubiquitous seismic energy mostly in the 2-20 s period band, known as microseismic noise. Between 2 and 10 s period, secondary microseisms (SM) are generated by swell reflections close to the shores and/or by opposing swells in the deep ocean. However, unique conditions are required in order for surface waves generated by deep-ocean microseisms to be observed on land. By comparing short-duration power spectral densities at both Atlantic shoreline and inland seismic stations, we show that ocean tides strongly modulate the seismic energy in a wide period band except between 2.5 and 5 s. This tidal proxy reveals the existence of an ex situ short-period contribution of the SM peak. Comparison with swell spectra at surrounding buoys suggests that the largest part of this extra energy comes from deep ocean-generated microseisms. The energy modulation might be also used in numerical models of microseismic generation to constrain coastal reflection coefficients.

  4. The relationship between 3-D kinematics and gliding performance in the southern flying squirrel, Glaucomys volans.

    PubMed

    Bishop, Kristin L

    2006-02-01

    Gliding is the simplest form of flight, yet relatively little is known about its mechanics in animals. The goal of this study was to describe the body position and performance of a gliding mammal and to identify correlates between kinematics and aerodynamic performance. To do this, I used a pair of high-speed digital cameras to record a portion of the middle of glides by southern flying squirrels, Glaucomys volans. The squirrels launched from a height of 4 m and landed on a vertical pole. Reflective markers were applied to anatomical landmarks and the 3-D coordinates of these points were computed to describe the kinematics of the glides. From these data I estimated the lift and drag generated during the glide, and correlated these variables with gliding performance as measured by glide angle, glide speed and stability. In the majority of the glide sequences the squirrels accelerated in the downward direction and accelerated horizontally forward as they moved through the calibrated volume in the middle of the glide trajectory, rather than exhibiting a steady glide in which the body weight is balanced by the resultant aerodynamic force. Compared to human engineered airfoils, the angles of attack used by the squirrels were unexpectedly high, ranging from 35.4 degrees to 53.5 degrees , far above the angle of attack at which an aircraft wing would typically stall. As expected based on aerodynamic theory, there was a negative correlation between angle of attack and lift coefficient, indicating that the wings are stalled, and a positive correlation between angle of attack and drag coefficient. Also as expected, there was a negative correlation between lift-to-drag ratio and angle of attack, as increasing angle of attack produced both less lift and more drag. Within glides, there was a strong correlation between nose-down pitching rotations and limb movements that tended to increase the angle of attack of the wing membrane, suggesting that the animals actively control

  5. Analysis on typhoon-induced microseisms from ocean bottom seismometer array

    NASA Astrophysics Data System (ADS)

    Lee, Tzu-Chuan; Lin, Jing-Yi

    2013-04-01

    Ocean-bottom seismometer (OBS) is usually used for active sources and passive listening experiments, such as air guns, explosives, earthquakes and other signals. In fact, the seismometer records not only the seismic waveforms but also noises generated by winds, waves, tides and other external forces. From the end of August to early September 2011, 15 OBSs were deployed offshore northeastern Taiwan for a recording period of about 20 days. At the end of August, the typhoon NANMADOL formed in the western Pacific and moved northwestward from the East Philippines and finally landed on the island of Taiwan. Due to storms or pressure changes caused by the typhoon, elastic waves would be directly or indirectly produced and recorded by the seismometers. In this study, by analyzing the seismic signals collected by the OBSs and the BATS stations, we investigate the influence induced by the changes of typhoon path and intensity on the submarine seismic noises. Preliminary results indicate that the seismic energy change related to the typhoon occurred mainly at 0.2-0.5 Hz, which is a relatively low frequency compared to that of earthquakes. The amplitude of this low-frequency noise increased when the distance between the typhoon and seismometer decreased. By comparing the seismic waves with the data collected from the marine weather buoy, we observed a positive correlation between the power of the low frequency microseisms and the wave height. This clearly indicates that the typhoon was the main source of microseisms during their passing. Owing to the ocean waves generated by the typhoon, the pressure altered by the water column change and recorded by the seismometers as seismic waves before being transmitted to the sea?oor. The spectrum analysis shows the presence of a high energy signals at 0.2-1 Hz with a period of about 12 hours which could be related to the tidal movements. In addition, the amplitude of the recorded microseisms is also affected by the depth of seismometers

  6. Investigation of Aerodynamic Capabilities of Flying Fish in Gliding Flight

    NASA Astrophysics Data System (ADS)

    Park, H.; Choi, H.

    In the present study, we experimentally investigate the aerodynamic capabilities of flying fish. We consider four different flying fish models, which are darkedged-wing flying fishes stuffed in actual gliding posture. Some morphological parameters of flying fish such as lateral dihedral angle of pectoral fins, incidence angles of pectoral and pelvic fins are considered to examine their effect on the aerodynamic performance. We directly measure the aerodynamic properties (lift, drag, and pitching moment) for different morphological parameters of flying fish models. For the present flying fish models, the maximum lift coefficient and lift-to-drag ratio are similar to those of medium-sized birds such as the vulture, nighthawk and petrel. The pectoral fins are found to enhance the lift-to-drag ratio and the longitudinal static stability of gliding flight. On the other hand, the lift coefficient and lift-to-drag ratio decrease with increasing lateral dihedral angle of pectoral fins.

  7. Substrate induced gliding for a nematic liquid crystal layer

    NASA Astrophysics Data System (ADS)

    Mema, Ensela; Cummings, Linda; Kondic, Lou

    2015-03-01

    The interaction between nematic liquid crystals (NLC) and polymer substrates is of current industrial interest, due to a desire to manufacture a new generation of flexible Liquid Crystal Displays (LCDs) for use in portable electronic devices. Polymer substrates present challenges because they can interact with the NLC, exhibiting a phenomenon known as gliding: the preferred orientation of the NLC molecules at the interface changes over timescales of minutes to hours. We present two models for gliding, inspired by the physics and chemistry of the interaction between the NLC and polymer substrate. These models, though simple, lead to non-trivial results, including loss of bistability, a finding that may have implications for display devices. Supported by NSF Grant No. DMS-1211713.

  8. [Hofmannsthal and the gliding out of this world].

    PubMed

    Tellenbach, H

    1988-01-01

    In the sphere of language, Hugo von Hofmannsthal was already in his childhood talented by nature. His first poems and essays he wrote when he was 17 years old, his first drama ("The Death of Tizian") in his 18th year. From the beginning he followed the great tradition of the theatre of Vienna. His lyrical creations end already before he turned 30 years. At this time the dramatist begins with the reception of the medieval mystery plays, Calderon and the greek-oriental myths. The phenomena of gliding-out-of-the-world are found before this time, in the period of his very own spiritual conceiving. They show a remarkable inclination to abandon the world of reality (Wirklichkeit, koinos kosmos): gliding into the world of dream and trance, of phantastic tales, of magic and demonia, of depersonalization and dilusion, of dying and of death (idios kosmos). These tendencies vanish when Hofmannsthal turns to more conventional topics. PMID:3073605

  9. Crystal geometry of screw dislocation glide in tungsten nanocrystals

    NASA Astrophysics Data System (ADS)

    Sadanov, E. V.

    2015-02-01

    A zigzag pattern of low-temperature dislocation glide occurring in tungsten nanocrystals in the intersecting planes {110} and {211}, which belong to the <111> crystallographic zone, has been revealed using field ion microscopy. It has been shown that cores of 1/2[111] screw dislocations are undissociated within the limits of the resolution of the field ion microscope. It has been found experimentally that surface atoms are displaced into metastable positions in the region of the trace of screw dislocation motion.

  10. Soil erosion by snow gliding - a first quantification attempt in a subalpine area in Switzerland

    NASA Astrophysics Data System (ADS)

    Meusburger, K.; Leitinger, G.; Mabit, L.; Mueller, M. H.; Walter, A.; Alewell, C.

    2014-09-01

    Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as a soil erosion agent for four different land use/land cover types in a subalpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide depositions, the fallout radionuclide 137Cs and modelling with the Revised Universal Soil Loss Equation (RUSLE). RUSLE permits the evaluation of soil loss by water erosion, the 137Cs method integrates soil loss due to all erosion agents involved, and the measurement of snow glide deposition sediment yield can be directly related to snow-glide-induced erosion. Further, cumulative snow glide distance was measured for the sites in the winter of 2009/2010 and modelled for the surrounding area and long-term average winter precipitation (1959-2010) with the spatial snow glide model (SSGM). Measured snow glide distance confirmed the presence of snow gliding and ranged from 2 to 189 cm, with lower values on the north-facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is an important information with respect to conservation planning and expected and ongoing land use changes in the Alps. Snow glide erosion estimated from the snow glide depositions was highly variable with values ranging from 0.03 to 22.9 t ha-1 yr-1 in the winter of 2012/2013. For sites affected by snow glide deposition, a mean erosion rate of 8.4 t ha-1 yr-1 was found. The difference in long-term erosion rates determined with RUSLE and 137Cs confirms the constant influence of snow-glide-induced erosion, since a large difference (lower proportion of water erosion compared to total net erosion) was observed for sites with high snow glide rates and vice versa. Moreover, the difference between RUSLE and 137Cs erosion

  11. Characteristics of Atmospheric Pressure Rotating Gliding Arc Plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Hao; Zhu, Fengsen; Tu, Xin; Bo, Zheng; Cen, Kefa; Li, Xiaodong

    2016-05-01

    In this work, a novel direct current (DC) atmospheric pressure rotating gliding arc (RGA) plasma reactor has been developed for plasma-assisted chemical reactions. The influence of the gas composition and the gas flow rate on the arc dynamic behaviour and the formation of reactive species in the N2 and air gliding arc plasmas has been investigated by means of electrical signals, high speed photography, and optical emission spectroscopic diagnostics. Compared to conventional gliding arc reactors with knife-shaped electrodes which generally require a high flow rate (e.g., 10–20 L/min) to maintain a long arc length and reasonable plasma discharge zone, in this RGA system, a lower gas flow rate (e.g., 2 L/min) can also generate a larger effective plasma reaction zone with a longer arc length for chemical reactions. Two different motion patterns can be clearly observed in the N2 and air RGA plasmas. The time-resolved arc voltage signals show that three different arc dynamic modes, the arc restrike mode, takeover mode, and combined modes, can be clearly identified in the RGA plasmas. The occurrence of different motion and arc dynamic modes is strongly dependent on the composition of the working gas and gas flow rate. supported by National Natural Science Foundation of China (No. 51576174), the Specialized Research Fund for the Doctoral Program of Higher Education of China (No. 20120101110099) and the Fundamental Research Funds for the Central Universities (No. 2015FZA4011)

  12. Abdominal breathing manoeuvre reduces passive drag acting on gliding swimmers.

    PubMed

    Maruyama, Yusuke; Yanai, Toshimasa

    2015-01-01

    The purpose of this study was to test the hypothesis that the passive drag acting on a gliding swimmer is reduced if the swimmer adopts an abdominal breathing manoeuvre (expanding the abdominal wall) rather than chest breathing manoeuvre (expanding the rib cage). Eleven male participants participated in this study. A specialised towing machine was used to tow each participant with tension set at various magnitudes and to record time series data of towing velocity. Participants were asked to inhale air by expanding the abdominal wall or the rib cage and to maintain the same body configuration throughout gliding. The steady-state velocity was measured and the coefficient of drag was calculated for each towing trial to compare between the breathing manoeuvres. The results showed that the towing velocity was increased by 0.02 m/s with a towing force of 34.3 N and by 0.06 m/s with a towing force of 98.1 N. The coefficient of drag was reduced by 5% with the abdominal breathing manoeuvre, which was found to be statistically significant (p < 0.05). These results indicate that adopting the abdominal breathing manoeuvre during gliding reduces the passive drag and the hypothesis was supported. PMID:26715235

  13. Functional anatomy of gliding membrane muscles in the sugar glider (Petaurus breviceps).

    PubMed

    Endo, H; Yokokawa, K; Kurohmaru, M; Hayashi, Y

    1998-02-01

    In order to clarify the morphological adaptation for gliding behavior in the marsupial mammals, the gliding membrane muscles in the sugar glider (Petaurus breviceps) were observed. Unlike the styliform cartilage in flying squirrels, the sugar glider has a well-developed tibiocarpalis muscle in the most lateral area of the gliding membrane. The gliding membrane substantially consists of the humerodorsalis and tibioabdominalis muscle complex. We believe that the thick tibiocarpalis bundle and the humerodorsalis and tibioabdominalis muscle complex may serve as a membrane controller in the gliding behavior. A characteristic thin membranous structure between the cutaneous and deeper muscles was observed. In addition to the direct powerful control exerted by trunk and limb movement, we suggest that indirect power conduction by this thin membranous structure may contribute to gliding membrane control. PMID:9488912

  14. Origin of microseisms in equatorial and southern Africa from analysis of broadband arrays

    NASA Astrophysics Data System (ADS)

    Euler, G. G.; Wiens, D. A.; Nyblade, A.

    2010-12-01

    Using broadband array noise correlation and frequency-wavenumber analysis, we find evidence for 4 distinct origins of microseisms in the 10-200mHz band: an unusual source of Rayleigh waves at 35-40mHz located in the Bight of Bonny, several abyssal locations with enhanced P-wave production at 100-200mHz, and both coastal and abyssal Rayleigh wave sources that vary in bandwidth. We find no evidence of persistent seismic noise generation on land. Data analyzed were 1Hz vertical component recordings from the Cameroon, Southern Africa, Tanzania, and Ethiopia PASSCAL experiments. The Bonny microseism is characterized by 2 well-defined peaks at 36 & 38mHz and is found to have a location on the continental shelf in the northern portion of the Bight of Bonny. Our preliminary analysis finds that the microseism is well represented as a point source with a frequency-dependent location and horizontal slowness. Additional peaks near 61mHz and 69mHz are associated with increased Rayleigh waves sourced from the Bight of Bonny but are below the frequency range expected for a doubled frequency microseism (70-80mHz). Strong P-wave energy is found to originate from abyssal regions west of Retkjanes Ridge near Greenland, South of the Kerguelen Islands, and in the vicinity of the triple-junction formed by the African, South American & Antarctic plates. We propose that the locations represent optimal sea floor bathymetry for efficient conversion of nonlinearly interfering ocean swell to seismic P waves. Maputo bay and Sofala bay in Mozambique, the Western Cape coast in South Africa, and the North Atlantic are the dominant sources of microseismic Rayleigh waves outside of 35-40mHz. All noise sources identified in our study have a seasonal signature with peak noise generation in the winter months of each location implying their energy is derived from ocean swell of extratropical cyclones.

  15. Detection of micro-sized air bubble defects in optical glass based on Mie theory

    NASA Astrophysics Data System (ADS)

    Zhang, Sai; Bai, Jian; Wang, Kaiwei; He, Fan; Zhou, Bin

    2015-10-01

    Mie scattering theory was shown in this paper to be suitable for analyzing the forward scattered light intensity distribution of micro-sized air bubble defects in glass, shining by a monochrome laser with a wavelength of 532um. The scattered light was measured by a high definition CCD camera. The scattering process can be classified as uncorrelated single scattering according to the properties of optical media. After calculating and smoothing the gray value of split rings of picture, Chahine algorithm was applied to reverse the size of defects. This technique was accurate to within 5% for defects with radii of <50um.

  16. Radiation enhanced basal plane dislocation glide in GaN

    NASA Astrophysics Data System (ADS)

    Yakimov, Eugene B.; Vergeles, Pavel S.; Polyakov, Alexander Y.; Lee, In-Hwan; Pearton, Stephen J.

    2016-05-01

    A movement of basal plane segments of dislocations in GaN films grown by epitaxial lateral overgrowth under low energy electron beam irradiation (LEEBI) was studied by the electron beam induced current (EBIC) method. Only a small fraction of the basal plane dislocation segments were susceptible to irradiation and the movement was limited to relatively short distances. The effect is explained by the radiation enhanced dislocation glide (REDG) in the structure with strong pinning. A dislocation velocity under LEEBI with a beam current lower than 1 nA was estimated as about 10 nm/s. The results assuming the REDG for prismatic plane dislocations were presented.

  17. Aerodynamic characteristics of flying fish in gliding flight.

    PubMed

    Park, Hyungmin; Choi, Haecheon

    2010-10-01

    The flying fish (family Exocoetidae) is an exceptional marine flying vertebrate, utilizing the advantages of moving in two different media, i.e. swimming in water and flying in air. Despite some physical limitations by moving in both water and air, the flying fish has evolved to have good aerodynamic designs (such as the hypertrophied fins and cylindrical body with a ventrally flattened surface) for proficient gliding flight. Hence, the morphological and behavioral adaptations of flying fish to aerial locomotion have attracted great interest from various fields including biology and aerodynamics. Several aspects of the flight of flying fish have been determined or conjectured from previous field observations and measurements of morphometric parameters. However, the detailed measurement of wing performance associated with its morphometry for identifying the characteristics of flight in flying fish has not been performed yet. Therefore, in the present study, we directly measure the aerodynamic forces and moment on darkedged-wing flying fish (Cypselurus hiraii) models and correlated them with morphological characteristics of wing (fin). The model configurations considered are: (1) both the pectoral and pelvic fins spread out, (2) only the pectoral fins spread with the pelvic fins folded, and (3) both fins folded. The role of the pelvic fins was found to increase the lift force and lift-to-drag ratio, which is confirmed by the jet-like flow structure existing between the pectoral and pelvic fins. With both the pectoral and pelvic fins spread, the longitudinal static stability is also more enhanced than that with the pelvic fins folded. For cases 1 and 2, the lift-to-drag ratio was maximum at attack angles of around 0 deg, where the attack angle is the angle between the longitudinal body axis and the flying direction. The lift coefficient is largest at attack angles around 30∼35 deg, at which the flying fish is observed to emerge from the sea surface. From glide polar

  18. Body wave microseisms from a distant storm revealed by Hi-net data

    NASA Astrophysics Data System (ADS)

    Nishida, K.

    2015-12-01

    Observations of microseisms were firmly established in 1940's. Their excitation sources are ocean swell activities. Microseisms from 0.1 to 0.5 Hz, which double the frequency, indicating the generation of the former through nonlinear wave-wave interaction of the latter. Because the swell activities are their sources, surface wave excitation is dominant.Recently body wave microseisms from a distant storm, however, have been focussed [e.g. Gerstoft et al. 2006]. They show clear teleseismic P waves excited by distant storms. A back-projection method could constrain the source distribution, which gives clues to their excitation mechanisms. Most studies focused, however, only vertical components.In this study, in order to constrain excitation mechanisms of microseisms, we conducted a 3-component array analysis using Hi-net operated by NIED, when a strong weather bomb hit the Atlantic ocean on Dec. 9th, 2014. We analyzed 3-component velocity-meters with a natural frequency of 1 Hz at 775 stations. The instrumental response was deconvolved by using the inverse filtering technique after reduction of common logger noise Their frequency-wavenumber spectra were calculated at 0.15 Hz. The spectra of a vertical component and a radial component show that clear teleseismic P-wave. The slowness of about 0.05 [s/km] and the back azimuth of -5 degrees are consistent with that of the P wave traveled from the weather bomb in the Atlantic ocean. The radial component shows SV wave with about 20% of P wave amplitudes. These observations could be explained by a single force source at the sea surface in the 1-D medium in the first order approximation. The transverse component also shows SH waves with about 10% of the P wave amplitude. The excitation source of P, SV and SH wave were located in the same small area by a backprojection analysis. These observations suggest that the steep topography and the thick sediment beneath the source area also affected the excitations.Observations of

  19. Coupled factors influencing detachment of nano- and micro-sized particles from primary minima.

    PubMed

    Shen, Chongyang; Lazouskaya, Volha; Jin, Yan; Li, Baoguo; Ma, Zhiqiang; Zheng, Wenjuan; Huang, Yuanfang

    2012-06-01

    This study examined the detachments of nano- and micro-sized colloids from primary minima in the presence of cation exchange by laboratory column experiments. Colloids were initially deposited in columns packed with glass beads at 0.2 M CaCl(2) in the primary minima of Derjaguin-Landau-Verwey-Overbeek (DLVO) interaction energies. Then, the columns were flushed with NaCl solutions with different ionic strengths (i.e., 0.001, 0.01, 0.1 and 0.2 M). Detachments were observed at all ionic strengths and were particularly significant for the nanoparticle. The detachments increased with increasing electrolyte concentration for the nanoparticle whereas increased from 0.001 M to 0.01 M and decreased with further increasing electrolyte concentration for the micro-sized colloid. The observations were attributed to coupled influence of cation exchange, short-range repulsion, surface roughness, surface charge heterogeneity, and deposition in the secondary minima. The detachments of colloids from primary minima challenge the common belief that colloid interaction in primary minimum is irreversible and resistant to disturbance in solution ionic strength and composition. Although the significance of surface roughness, surface charge heterogeneity, and secondary minima on colloid deposition has been widely recognized, our study implies that they also play important roles in colloid detachment. Whereas colloid detachment is frequently associated with decrease of ionic strength, our results show that increase of ionic strength can also cause detachment due to influence of cation exchange. PMID:22575872

  20. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes.

    PubMed

    Mor, Flavio M; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-28

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λ(em) = 532 nm) at half the excitation wavelength (λ(ex) = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET). PMID:26956197

  1. Single potassium niobate nano/microsized particles as local mechano-optical Brownian probes

    NASA Astrophysics Data System (ADS)

    Mor, Flavio M.; Sienkiewicz, Andrzej; Magrez, Arnaud; Forró, László; Jeney, Sylvia

    2016-03-01

    Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal fluctuations and optical forces of singly-trapped KNbO3 particles within the optical trapping volume of a PFM microscope. We also show that, under near-infrared (NIR) excitation of the highly focused laser beam of the PFM microscope, a single optically-trapped KNbO3 particle reveals a strong SHG signal manifested by a narrow peak (λem = 532 nm) at half the excitation wavelength (λex = 1064 nm). Moreover, we demonstrate that the thus induced SHG emission can be used as a local light source that is capable of optically exciting molecules of an organic dye, Rose Bengal (RB), which adhere to the particle surface, through the mechanism of luminescence energy transfer (LET).Perovskite alkaline niobates, due to their strong nonlinear optical properties, including birefringence and the capability to produce second-harmonic generation (SHG) signals, attract a lot of attention as potential candidates for applications as local nano/microsized mechano-optical probes. Here, we report on an implementation of photonic force microscopy (PFM) to explore the Brownian motion and optical trappability of monocrystalline potassium niobate (KNbO3) nano/microsized particles having sizes within the range of 50 to 750 nm. In particular, we exploit the anisotropic translational diffusive regime of the Brownian motion to quantify thermal

  2. Block glides offshore Newport Beach, Southern California continental margin

    SciTech Connect

    Greene, H.G.; Clarke, S.H. Jr.; Kennedy, M.P.

    1988-01-01

    The continental slope offshore Newport Beach, California, is characterized by a relatively gentle (approximately 1/sup 0/) grade and is dissected by numerous channels and canyons, of which the most conspicuous is Newport Canyon. An unusual series of block-glide landslides have developed on this lope adjacent to many of these channels. Locally, secondary channels that develop along pull-apart fractures between the slide blocks may service as conduits for downslope sediment movement. A detailed seismic-reflection survey of the area shows that the slope is underlain by soft water-saturated unstable sediment of Quaternary age. The block-glides lie wholly within this sediment; displaced blocks appear to have moved only a short distance downslope and are preserved as intact masses that exhibit downward increasing internal deformation. This deformation reaches a maximum near the front of the displaced mass and in basal beds nearest the slip surface. The morphology of the blocks and their intervening channellike erosional scarps is similar to that of glacial blocks and their associated bergschrunds. The formation of new scarps and the widening of channels formed as pull-aparts by the ongoing process of block movement may contribute to headward erosion and widening of Newport Canyon and its tributaries. Slope failure might be greatly enhanced by strong ground motion associated with nearby earthquakes. The authors suspect that renewed movement occurs on these blocks during major seismic events on the nearby Newport-Inglewood fault (e.g., 1933 M/sub L/ 6.3 event).

  3. Gliding arc in tornado using a reverse vortex flow

    SciTech Connect

    Kalra, Chiranjeev S.; Cho, Young I.; Gutsol, Alexander; Fridman, Alexander; Rufael, Tecle S.

    2005-02-01

    The present article reports a new gliding arc (GA) system using a reverse vortex flow ('tornado') in a cylindrical reactor (gliding arc in tornado, or GAT), as used to preserve the main advantages of traditional GA systems and overcome their main drawbacks. The primary advantages of traditional GA systems retained in the present GAT are the possibility to generate transitional plasma and to avoid considerable electrode erosion. In contrast to a traditional GA, the new GAT system ensures much more uniform gas treatment and has a significantly larger gas residence time in the reactor. The present article also describes the design of the new reactor and its stable operation regime when the variation of GAT current is very small. These features are understood to be very important for most viable applications. Additionally the GAT provides near-perfect thermal insulation from the reactor wall, indicating that the present GAT does not require the reactor wall to be constructed of high-temperature materials. The new GAT system, with its unique properties such as a high level of nonequilibrium and a large residence time, looks very promising for many industrial applications including fuel conversion, carbon dioxide conversion to carbon monoxide and oxygen, surface treatment, waste treatment, flame stabilization, hydrogen sulfide treatment, etc.

  4. 14 CFR 29.71 - Helicopter angle of glide: Category B.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Helicopter angle of glide: Category B. 29... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Performance § 29.71 Helicopter angle of glide: Category B. For each category B helicopter, except multiengine helicopters meeting...

  5. 14 CFR 29.71 - Helicopter angle of glide: Category B.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Helicopter angle of glide: Category B. 29... AIRCRAFT AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY ROTORCRAFT Flight Performance § 29.71 Helicopter angle of glide: Category B. For each category B helicopter, except multiengine helicopters meeting...

  6. Effortful Pitch Glide: A Potential New Exercise Evaluated by Dynamic MRI

    ERIC Educational Resources Information Center

    Miloro, Keri Vasquez; Pearson, William G., Jr.; Langmore, Susan E.

    2014-01-01

    Purpose: The purpose of this study was to compare the biomechanics of the effortful pitch glide (EPG) with swallowing using dynamic MRI. The EPG is a combination of a pitch glide and a pharyngeal squeeze maneuver for targeting laryngeal and pharyngeal muscles. The authors hypothesized that the EPG would elicit significantly greater structural…

  7. High Order Large Eddy Simulation (LES) of Gliding Snake Aerodynamics: Effect of 3D Flow on Gliding Performance

    NASA Astrophysics Data System (ADS)

    Delorme, Yann; Hassan, Syed Harris; Socha, Jake; Vlachos, Pavlos; Frankel, Steven

    2014-11-01

    Chrysopelea paradisi are snakes that are able to glide over long distances by morphing the cross section of their bodies from circular to a triangular airfoil, and undulating through the air. Snake glide is characterized by relatively low Reynolds number and high angle of attack as well as three dimensional and unsteady flow. Here we study the 3D dynamics of the flow using an in-house high-order large eddy simulation code. The code features a novel multi block immersed boundary method to accurately and efficiently represent the complex snake geometry. We investigate the steady state 3-dimensionality of the flow, especially the wake flow induced by the presence of the snake's body, as well as the vortex-body interaction thought to be responsible for part of the lift enhancement. Numerical predictions of global lift and drag will be compared to experimental measurements, as well as the lift distribution along the body of the snake due to cross sectional variations. Comparisons with previously published 2D results are made to highlight the importance of 3-dimensional effects. Additional efforts are made to quantify properties of the vortex shedding and Dynamic Mode Decomposition (DMD) is used to analyse the main modes responsible for the lift and drag forces.

  8. Gliding Motility and Por Secretion System Genes Are Widespread among Members of the Phylum Bacteroidetes

    PubMed Central

    Zhu, Yongtao

    2013-01-01

    The phylum Bacteroidetes is large and diverse, with rapid gliding motility and the ability to digest macromolecules associated with many genera and species. Recently, a novel protein secretion system, the Por secretion system (PorSS), was identified in two members of the phylum, the gliding bacterium Flavobacterium johnsoniae and the nonmotile oral pathogen Porphyromonas gingivalis. The components of the PorSS are not similar in sequence to those of other well-studied bacterial secretion systems. The F. johnsoniae PorSS genes are a subset of the gliding motility genes, suggesting a role for the secretion system in motility. The F. johnsoniae PorSS is needed for assembly of the gliding motility apparatus and for secretion of a chitinase, and the P. gingivalis PorSS is involved in secretion of gingipain protease virulence factors. Comparative analysis of 37 genomes of members of the phylum Bacteroidetes revealed the widespread occurrence of gliding motility genes and PorSS genes. Genes associated with other bacterial protein secretion systems were less common. The results suggest that gliding motility is more common than previously reported. Microscopic observations confirmed that organisms previously described as nonmotile, including Croceibacter atlanticus, “Gramella forsetii,” Paludibacter propionicigenes, Riemerella anatipestifer, and Robiginitalea biformata, exhibit gliding motility. Three genes (gldA, gldF, and gldG) that encode an apparent ATP-binding cassette transporter required for F. johnsoniae gliding were absent from two related gliding bacteria, suggesting that the transporter may not be central to gliding motility. PMID:23123910

  9. Natural glide slab avalanches, Glacier National Park, USA: A unique hazard and forecasting challenge

    USGS Publications Warehouse

    Reardon, Blase; Fagre, Daniel B.; Dundas, Mark; Lundy, Chris

    2006-01-01

    In a museum of avalanche phenomena, glide cracks and glide avalanches might be housed in the “strange but true” section. These oddities are uncommon in most snow climates and tend to be isolated to specific terrain features such as bedrock slabs. Many glide cracks never result in avalanches, and when they do, the wide range of time between crack formation and slab failure makes them highly unpredictable. Despite their relative rarity, glide cracks and glide avalanches pose a regular threat and complex forecasting challenge during the annual spring opening of the Going-to-the-Sun Road in Glacier National Park, U.S.A. During the 2006 season, a series of unusual glide cracks delayed snow removal operations by over a week and provided a unique opportunity to record detailed observations of glide avalanches and characterize their occurrence and associated weather conditions. Field observations were from snowpits, crown profiles and where possible, measurements of slab thickness, bed surface slope angle, substrate and other physical characteristics. Weather data were recorded at one SNOTEL site and two automated stations located from 0.6-10 km of observed glide slab avalanches. Nearly half (43%) of the 35 glide slab avalanches recorded were Class D2-2.5, with 15% Class D3-D3.5. The time between glide crack opening and failure ranged from 2 days to over six weeks, and the avalanches occurred in cycles associated with loss of snow water equivalent and spikes in temperature and radiation. We conclude with suggest ions for further study.

  10. Soil erosion by snow gliding - a first quantification attempt in a sub-alpine area, Switzerland

    NASA Astrophysics Data System (ADS)

    Meusburger, K.; Leitinger, G.; Mabit, L.; Mueller, M. H.; Walter, A.; Alewell, C.

    2014-03-01

    Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as soil erosion agent for four different land use/land cover types in a sub-alpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide deposits, the fallout radionuclide 137Cs, and modelling with the Revised Universal Soil Loss Equation (RUSLE). The RUSLE model is suitable to estimate soil loss by water erosion, while the 137Cs method integrates soil loss due to all erosion agents involved. Thus, we hypothesise that the soil erosion rates determined with the 137Cs method are higher and that the observed discrepancy between the soil erosion rate of RUSLE and the 137Cs method is related to snow gliding and sediment concentrations in the snow glide deposits. Cumulative snow glide distance was measured for the sites in the winter 2009/10 and modelled for the surrounding area with the Spatial Snow Glide Model (SSGM). Measured snow glide distance ranged from 2 to 189 cm, with lower values at the north facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is important information with respect to conservation planning and expected land use changes in the Alps. Our hypothesis was confirmed: the difference of RUSLE and 137Cs erosion rates was related to the measured snow glide distance (R2= 0.64; p < 0.005) and snow sediment yields (R2 = 0.39; p = 0.13). A high difference (lower proportion of water erosion compared to total net erosion) was observed for high snow glide rates and vice versa. The SSGM reproduced the relative difference of the measured snow glide values under different land uses and land cover types. The resulting map highlighted the relevance of snow gliding for large parts of the investigated area. Based

  11. GlideScope and Frova Introducer for Difficult Airway Management

    PubMed Central

    Ciccozzi, Alessandra; Guetti, Cristiana; Papola, Roberta; Paladini, Antonella; Varrassi, Giustino; Marinangeli, Franco

    2013-01-01

    The introduction into clinical practice of new tools for intubation as videolaringoscopia has dramatically improved the success rate of intubation and the work of anesthesiologists in what is considered the most delicate maneuver. Nevertheless intubation difficulties may also be encountered with good anatomical visualization of glottic structures in videolaringoscopia. To overcome the obstacles that may occur both in a difficult provided intubation such as those unexpected, associated endotracheal introducer able to facilitate the passage of the endotracheal tube through the vocal cords into the trachea may be useful. We report 4 cases of difficult intubation planned and unplanned and completed successfully using the GlideScope videolaryngoscope associated with endotracheal Frova introducer. PMID:23991339

  12. Degradation of tetrafluoroethane using three-phase gliding arc plasma

    NASA Astrophysics Data System (ADS)

    Pacheco, J.; García, M.; Pacheco, M.; Valdivia, R.; Rivera, C.; Garduño, M.

    2012-06-01

    The use of many chlorofluorocarbons (CFC's) has negatively impacted the ozone layer. The Montreal Protocol was implemented, as a temporary solution for this problem by replacing CFC's by hydrofluorocarbons (HFC's). These kinds of gases have the propriety to be free of chlorine. However, in a next future, the Montreal Protocol also considers the replacement of HFC's because they have a high global warming potential when they enter in contact with the atmosphere. One of the methods to remove those compounds is the gliding arc plasma because it presents some advantages. The inlet system works near the atmospheric pressure and has a transition region from plasma at thermodynamic local partial equilibrium to non-thermal plasma; allowing high gas and electronic temperatures. Results present a promissory possibility to be scaled and to give an industrial service.

  13. Glide planes symmetry in the organization of some sulfide structures

    NASA Astrophysics Data System (ADS)

    Borisov, S. V.; Magarill, S. A.; Pervukhina, N. V.

    2016-03-01

    The role of glide planes in the organization of structures is shown based on a crystallographic analysis of the monoclinic structures of TlAs3S5 and Tl2(As,Sb)3S13 sulfides. In the first structure, cations and anions form systems (with identical geometries) of two face-centered sublattices, linked by the c plane, with the effect of unified "two-dimensional" (2D) ordering. The second structure, exhibiting signs of order-disorder (OD) type, is interpreted as a superposition of two noncentrosymmetric components with independent cation and anion sublattices, which, however, also form a regular 2D order due to the n plane. The stabilizing role of Tl cations in the geometry of cation matrices is indicated.

  14. Employment of hypersonic glide vehicles: Proposed criteria for use

    SciTech Connect

    Olguin, Abel

    2014-07-01

    Hypersonic Glide Vehicles (HGVs) are a type of reentry vehicle that couples the high speed of ballistic missiles with the maneuverability of aircraft. The HGV has been in development since the 1970s, and its technology falls under the category of Conventional Prompt Global Strike (CPGS) weapons. As noted by James M. Acton, a senior associate in the Nuclear Policy Program at the Carnegie Endowment, CPGS is a “missile in search of a mission.” With the introduction of any significant new military capability, a doctrine for use—including specifics regarding how, when and where it would be used, as well as tactics, training and procedures—must be clearly defined and understood by policy makers, military commanders, and planners. In this paper, benefits and limitations of the HGV are presented. Proposed criteria and four scenarios illustrate a possible method for assessing when to use an HGV.

  15. Leaping shampoo glides on a lubricating air layer

    NASA Astrophysics Data System (ADS)

    Lee, S.; Li, E. Q.; Marston, J. O.; Bonito, A.; Thoroddsen, S. T.

    2013-06-01

    When a stream of shampoo is fed onto a pool in one's hand, a jet can leap sideways or rebound from the liquid surface in an intriguing phenomenon known as the Kaye effect. Earlier studies have debated whether non-Newtonian effects are the underlying cause of this phenomenon, making the jet glide on top of a shear-thinning liquid layer, or whether an entrained air layer is responsible. Herein we show unambiguously that the jet slides on a lubricating air layer. We identify this layer by looking through the pool liquid and observing its rupture into fine bubbles. The resulting microbubble sizes suggest this air layer is of submicron thickness. This thickness estimate is also supported by the tangential deceleration of the jet during the rebounding.

  16. Long-range correlations of microseism-band pressure fluctuations in the ocean

    NASA Astrophysics Data System (ADS)

    Ball, Justin S.; Godin, Oleg A.; Evers, Läslo G.; Lv, Cheng

    2016-03-01

    We investigate the spatial coherence of underwater ambient noise using a yearlong time series measured off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the existence of two weakly dispersive normal modes in the microseism frequency range, with the group speed of one of the normal modes being smaller than the sound speed in water. The agreement justifies our interpretation of the peaks of the measured cross-correlation function of ambient noise as modal arrivals, with dispersion that is sensitive to crustal velocity structure. Our observations are consistent with Scholte to Moho head wave coupled propagation, with double mode conversion occurring due to the bathymetric variations between receivers. We thus demonstrate the feasibility of interrogating crustal properties using noise interferometry of moored hydrophone data at ranges in excess of 120 km.

  17. Calculation and experimental validation of spectral properties of microsize grains surrounded by nanoparticles.

    PubMed

    Yu, Haitong; Liu, Dong; Duan, Yuanyuan; Wang, Xiaodong

    2014-04-01

    Opacified aerogels are particulate thermal insulating materials in which micrometric opacifier mineral grains are surrounded by silica aerogel nanoparticles. A geometric model was developed to characterize the spectral properties of such microsize grains surrounded by much smaller particles. The model represents the material's microstructure with the spherical opacifier's spectral properties calculated using the multi-sphere T-matrix (MSTM) algorithm. The results are validated by comparing the measured reflectance of an opacified aerogel slab against the value predicted using the discrete ordinate method (DOM) based on calculated optical properties. The results suggest that the large particles embedded in the nanoparticle matrices show different scattering and absorption properties from the single scattering condition and that the MSTM and DOM algorithms are both useful for calculating the spectral and radiative properties of this particulate system. PMID:24718167

  18. Long-range correlations of microseism-band pressure fluctuations in the ocean

    NASA Astrophysics Data System (ADS)

    Ball, Justin S.; Godin, Oleg A.; Evers, Läslo G.; Lv, Cheng

    2016-08-01

    We investigate the spatial coherence of underwater ambient noise using a yearlong time-series measured off Ascension Island. Qualitative agreement with observed cross-correlations is achieved using a simple range-dependent model, constrained by earlier, active tomographic studies in the area. In particular, the model correctly predicts the existence of two weakly dispersive normal modes in the microseism frequency range, with the group speed of one of the normal modes being smaller than the sound speed in water. The agreement justifies our interpretation of the peaks of the measured cross-correlation function of ambient noise as modal arrivals, with dispersion that is sensitive to crustal velocity structure. Our observations are consistent with Scholte to Moho head wave coupled propagation, with double mode conversion occurring due to the bathymetric variations between receivers. We thus demonstrate the feasibility of interrogating crustal properties using noise interferometry of moored hydrophone data at ranges in excess of 120 km.

  19. Flavobacterium tistrianum sp. nov., a gliding bacterium isolated from soil.

    PubMed

    Suwannachart, Chatrudee; Rueangyotchanthana, Kanjana; Srichuay, Suksan; Pheng, Sophea; Fungsin, Bundit; Phoonsiri, Chantara; Kim, Song-Gun

    2016-06-01

    A novel gliding bacterial strain, GB 56.1T, was obtained from soil at the Sakaerat Biosphere Reserve, in Nakhon Ratchasima province, Thailand; the strain was characterized using a polyphasic approach. Cells were Gram-stain-negative, yellow, rod shaped and devoid of flagella, but showed gliding motility. Phylogenetic analysis based on 16S rRNA gene sequences found that GB 56.1T was a member of the genus Flavobacterium and that the strain shared the highest sequence similarities with Flavobacterium nitrogenifigens (98.4 %), Flavobacterium anhuiense(98.3 %) and Flavobacterium ginsenosidimutans (97.9 %). The similarities of the sequences of all other species of the genus Flavobacterium were below 97.4 %. The major respiratory quinone of strain GB 56.1T was MK-6; fatty acids were iso-C15:0, C16:1ω6c/C16:1ω7c, C16:0 and C16:0 3-OH. The major polar lipids were phosphatidylethanolamine, phosphatidylserine, an unidentified amino lipid and four polar lipids. The DNA G+C content of this strain was 34.2 mol%. The DNA-DNA relatedness of GB 56.1T was highest against F.anhuiense, with a value of 37.6 %. On the basis of morphological, physiological and chemotaxonomic characteristics, DNA-DNA hybridization relatedness and 16S rRNA gene sequence analysis, we conclude that strain GB 56.1T represents a novel species, for which the name Flavobacterium tistrianum sp. nov. is proposed. The type strain is GB 56.1T (=TISTR 1612T =KCTC 42679T). PMID:26970735

  20. An investigation into a micro-sized droplet impinging on a surface with sharp wettability contrast

    NASA Astrophysics Data System (ADS)

    Lim, C. Y.; Lam, Y. C.

    2014-10-01

    An experimental investigation was conducted into a micro-sized droplet jetted onto a surface with sharp wettability contrast. The dynamics of micro-sized droplet impingement on a sharp wettability contrast surface, which is critical in inkjet printing technology, has not been investigated in the literature. Hydrophilic lines with line widths ranging from 27 to 53 µm, and contact angle ranging from 17° to 77°, were patterned on a hydrophobic surface with a contact angle of 107°. Water droplets with a diameter of 81 µm were impinged at various offset distances from the centre of the hydrophilic line. The evolution of the droplet upon impingement can be divided into three distinct phases, namely the kinematic phase, the translating phase where the droplet moves towards the centre of the hydrophilic line, and the conforming phase where the droplet spreads along the line. The key parameters affecting the conformability of the droplet to the hydrophilic line pattern are the ratio of the line width to the initial droplet diameter and the contact angle of the hydrophilic line. The droplet will only conform completely to the hydrophilic pattern if the line width is not overly small relative to the droplet and the contact angle of the hydrophilic line is sufficiently low. The impact offset distance does not affect the final shape and final location of the droplet, as long as part of the droplet touches the hydrophilic line upon impingement. This process has a significant impact on inkjet printing technology as high accuracy of inkjet droplet deposition and shape control can be achieved through wettability patterning.

  1. STS-41 Discovery, OV-103, glides over concrete runway 22 at EAFB, California

    NASA Technical Reports Server (NTRS)

    1990-01-01

    STS-41 Discovery, Orbiter Vehicle (OV) 103, with nose landing gear (NLG) and main landing gear (MLG) deployed, glides over concrete runway 22 at Edwards Air Force Base (EAFB), California, prior to touchdown.

  2. Impact of snow gliding on soil redistribution for a sub-alpine area in Switzerland

    NASA Astrophysics Data System (ADS)

    Meusburger, K.; Leitinger, G.; Mabit, L.; Mueller, M. H.; Alewell, C.

    2013-07-01

    The aim of this study is to assess the importance of snow gliding as soil erosion agent for four different land use/land cover types in a sub-alpine area in Switzerland. The 14 investigated sites are located close to the valley bottom at approximately 1500 m a.s.l., while the elevation of the surrounding mountain ranges is about 2500 m a.s.l. We used two different approaches to estimate soil erosion rates: the fallout radionuclide 137Cs and the Revised Universal Soil Loss Equation (RUSLE). The RUSLE model is suitable to estimate soil loss by water erosion, while the 137Cs method integrates soil loss due to all erosion agents involved. Thus, we hypothesise that the soil erosion rates determined with the 137Cs method are higher and that the observed discrepancy between the erosion rate of RUSLE and the 137Cs method is related to snow gliding. Cumulative snow glide distance was measured for the sites in the winter 2009/2010 and modelled for the surrounding area with the Spatial Snow Glide Model (SSGM). Measured snow glide distance range from 0 to 189 cm with lower values for the north exposed slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is an important information with respect to conservation planning and expected land use changes in the Alps. Our hypothesis was confirmed, the difference of RUSLE and 137Cs erosion rates was correlated to the measured snow glide distance (R2 = 0.73; p < 0.005). A high difference (lower proportion of water erosion compared to total net erosion) was observed for high snow glide rates and vice versa. The SSGM reproduced the relative difference of the measured snow glide values between different land use/land cover types. The resulting map highlights the relevance of snow gliding for large parts of the investigated area. Based on these results, we conclude that snow gliding is a key process impacting soil erosion pattern and magnitude in sub-alpine areas with similar

  3. Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid Microraptor gui

    PubMed Central

    Alexander, David E.; Gong, Enpu; Martin, Larry D.; Burnham, David A.; Falk, Amanda R.

    2010-01-01

    Fossils of the remarkable dromaeosaurid Microraptor gui and relatives clearly show well-developed flight feathers on the hind limbs as well as the front limbs. No modern vertebrate has hind limbs functioning as independent, fully developed wings; so, lacking a living example, little agreement exists on the functional morphology or likely flight configuration of the hindwing. Using a detailed reconstruction based on the actual skeleton of one individual, cast in the round, we developed light-weight, three-dimensional physical models and performed glide tests with anatomically reasonable hindwing configurations. Models were tested with hindwings abducted and extended laterally, as well as with a previously described biplane configuration. Although the hip joint requires the hindwing to have at least 20° of negative dihedral (anhedral), all configurations were quite stable gliders. Glide angles ranged from 3° to 21° with a mean estimated equilibrium angle of 13.7°, giving a lift to drag ratio of 4.1:1 and a lift coefficient of 0.64. The abducted hindwing model’s equilibrium glide speed corresponds to a glide speed in the living animal of 10.6 m·s−1. Although the biplane model glided almost as well as the other models, it was structurally deficient and required an unlikely weight distribution (very heavy head) for stable gliding. Our model with laterally abducted hindwings represents a biologically and aerodynamically reasonable configuration for this four-winged gliding animal. M. gui’s feathered hindwings, although effective for gliding, would have seriously hampered terrestrial locomotion. PMID:20133792

  4. Efficiency of lift production in flapping and gliding flight of swifts.

    PubMed

    Henningsson, Per; Hedenström, Anders; Bomphrey, Richard J

    2014-01-01

    Many flying animals use both flapping and gliding flight as part of their routine behaviour. These two kinematic patterns impose conflicting requirements on wing design for aerodynamic efficiency and, in the absence of extreme morphing, wings cannot be optimised for both flight modes. In gliding flight, the wing experiences uniform incident flow and the optimal shape is a high aspect ratio wing with an elliptical planform. In flapping flight, on the other hand, the wing tip travels faster than the root, creating a spanwise velocity gradient. To compensate, the optimal wing shape should taper towards the tip (reducing the local chord) and/or twist from root to tip (reducing local angle of attack). We hypothesised that, if a bird is limited in its ability to morph its wings and adapt its wing shape to suit both flight modes, then a preference towards flapping flight optimization will be expected since this is the most energetically demanding flight mode. We tested this by studying a well-known flap-gliding species, the common swift, by measuring the wakes generated by two birds, one in gliding and one in flapping flight in a wind tunnel. We calculated span efficiency, the efficiency of lift production, and found that the flapping swift had consistently higher span efficiency than the gliding swift. This supports our hypothesis and suggests that even though swifts have been shown previously to increase their lift-to-drag ratio substantially when gliding, the wing morphology is tuned to be more aerodynamically efficient in generating lift during flapping. Since body drag can be assumed to be similar for both flapping and gliding, it follows that the higher total drag in flapping flight compared with gliding flight is primarily a consequence of an increase in wing profile drag due to the flapping motion, exceeding the reduction in induced drag. PMID:24587260

  5. Seasonal variations in the Rayleigh-to-Love wave ratio in the secondary microseism from colocated ring laser and seismograph

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Hadziioannou, Céline; Igel, Heiner; Wassermann, Joachim; Schreiber, Ulrich; Gebauer, André; Chow, Bryant

    2016-04-01

    Monthly variations in the ratio of Rayleigh-to-Love waves in the secondary microseism are obtained from a colocated ring laser and an STS-2 seismograph at Wettzell, Germany. Two main conclusions are derived for the Rayleigh-to-Love wave kinetic energy ratios in the secondary microseism; first, the energy ratio is in the range 0.8-0.9 (<1.0) throughout a year except for June and July. It means that Love wave energy is larger than Rayleigh wave energy most of the year by about 10-20%. Second, this ratio suddenly increases to 1.0-1.2 in June and July, indicating a larger fraction of Rayleigh wave energy. This change suggests that the locations and behaviors of excitation sources are different in these months.

  6. Seasonal variation in Rayleigh-to-Love wave ratio in the secondary microseism

    NASA Astrophysics Data System (ADS)

    Tanimoto, T.; Hadziioannou, C.; Igel, H.; Wassermann, J. M.; Schreiber, U.; Gebauer, A.; Chow, B.

    2015-12-01

    The Ring Laser (the G-ring) at Wettzell (WET), Germany, is a rotation-measurement instrument that can monitor tiny variations in seismic noise. It essentially records only SH-type signals. Combined with a co-located seismograph (three-component seismograph STS-2), we can monitor the amount of Love waves from this instrument and that of Rayleigh waves from the STS seismograph. We report on seasonal variation of Rayleigh-to-Love wave ratio in the secondary microseism. The first step in our analysis is to obtain stacked Fourier spectra that were least affected by earthquakes. We used two earthquake catalogues to do this; the GCMT (Global Centroid Moment Tensor, Earthquakes M > 5.5) catalogue and the EMSC (European-Mediterranean Seismic Centre) catalogue for regional earthquakes (distance < 1000 km) with M > 4.5. We then created monthly averages of noise Fourier spectra for the frequency range 0.13-0.30 Hz using both the G-ring and STS data from 2009 to 2015. Monthly spectra show clear seasonal variations for the secondary microseism. We obtained surface vertical acceleration from STS and surface transverse acceleration from G-ring from which we can directly measure the Rayleigh-to-Love wave ratio. The procedure is the same with an account in our recent GRL paper (Tanimoto et al., 2015). Comparison between vertical acceleration and transverse acceleration shows that Rayleigh-wave surface amplitudes are about 20 percent larger than Love waves but in terms of kinetic energy this ratio will be different. We converted these ratios of surface amplitude to those of kinetic energy using an available earth model (Fichtner et al., 2013). The averaged ratio over the frequency band 0.13-0.30 Hz shows is in the range 0.6-0.8 in spring, autumn and winter but it increases to about 1.2 in summer. Except for the summer, the amount of Love waves are higher but the amount of Rayleigh waves increases in summer and appears to exceed that of Love waves.

  7. Sustainable design of high-performance microsized microbial fuel cell with carbon nanotube anode and air cathode.

    PubMed

    Mink, Justine E; Hussain, Muhammad Mustafa

    2013-08-27

    Microbial fuel cells (MFCs) are a promising alternative energy source that both generates electricity and cleans water. Fueled by liquid wastes such as wastewater or industrial wastes, the microbial fuel cell converts waste into energy. Microsized MFCs are essentially miniature energy harvesters that can be used to power on-chip electronics, lab-on-a-chip devices, and/or sensors. As MFCs are a relatively new technology, microsized MFCs are also an important rapid testing platform for the comparison and introduction of new conditions or materials into macroscale MFCs, especially nanoscale materials that have high potential for enhanced power production. Here we report a 75 μL microsized MFC on silicon using CMOS-compatible processes and employ a novel nanomaterial with exceptional electrochemical properties, multiwalled carbon nanotubes (MWCNTs), as the on-chip anode. We used this device to compare the usage of the more commonly used but highly expensive anode material gold, as well as a more inexpensive substitute, nickel. This is the first anode material study done using the most sustainably designed microsized MFC to date, which utilizes ambient oxygen as the electron acceptor with an air cathode instead of the chemical ferricyanide and without a membrane. Ferricyanide is unsustainable, as the chemical must be continuously refilled, while using oxygen, naturally found in air, makes the device mobile and is a key step in commercializing this for portable technology such as lab-on-a-chip for point-of-care diagnostics. At 880 mA/m(2) and 19 mW/m(2) the MWCNT anode outperformed the others in both current and power densities with between 6 and 20 times better performance. All devices were run for over 15 days, indicating a stable and high-endurance energy harvester already capable of producing enough power for ultra-low-power electronics and able to consistently power them over time. PMID:23899322

  8. Strongly gliding harmonic tremor during the 2009 eruption of Redoubt Volcano

    USGS Publications Warehouse

    Hotovec, Alicia J.; Prejean, Stephanie G.; Vidale, John E.; Gomberg, Joan S.

    2013-01-01

    During the 2009 eruption of Redoubt Volcano, Alaska, gliding harmonic tremor occurred prominently before six nearly consecutive explosions during the second half of the eruptive sequence. The fundamental frequency repeatedly glided upward from < 1 Hz to as high as 30 Hz in less than 10 min, followed by a relative seismic quiescence of 10 to 60 s immediately prior to explosion. High frequency (5 to 20 Hz) gliding returned during the extrusive phase, and lasted for 20 min to 3 h at a time. Although harmonic tremor is not uncommon at volcanoes, tremor at such high frequencies is a rare observation. These frequencies approach or exceed the plausible upper limits of many models that have been suggested for volcanic tremor. We also analyzed the behavior of a swarm of repeating earthquakes that immediately preceded the first instance of pre-explosion gliding harmonic tremor. We find that these earthquakes share several traits with upward gliding harmonic tremor, and favor the explanation that the gliding harmonic tremor at Redoubt Volcano is created by the superposition of increasingly frequent and regular, repeating stick–slip earthquakes through the Dirac comb effect.

  9. Harmonic Tremor and Gliding: Acoustic Chug Swarms at Tungurahua, Ecuador

    NASA Astrophysics Data System (ADS)

    Lees, J. M.; Ruiz, M. C.

    2010-12-01

    On May 28, 2010, a new eruptive episode started at Tungurahua volcano with a mid-size volcanic explosion, followed by a sustained ash emission with high ash column (10 km high), pyroclastic flows running down western and southern flanks and seismic and infrasonic tremor. After a quiescence period of 5 hours, Tungurahua Volcano in Ecuador experienced a major swarm of volcanic explosions including hundreds of events recorded up to June 18, 2010 on seismic and acoustic instrumentation in the vicinity of the active vent. Explosions exhibited extremely high excess pressures in the infrasonic band as well as in the audio band. Thirteen events produced pressures larger than 160 dB at 1 km distance from the vent. Among the diverse signals recorded during the week long episode of explosive activity, numerous sequences of harmonic tremor show significant patterns of modulation, or frequency gliding. Some harmonic tremor extended for as long as 30 minutes, often with as many as 10 different regimes of distinct behavior in one sequence of explosions. We applied automated search ridge identification using Gabor and Wavelet transforms in conjunction with time-domain analyses to derive high precision estimates of time varying periodicities. One pattern observed was a rise in dominant frequency as the tremor amplitude diminished prior to the onset of a second sequence of nearly monotonic pulsations. We speculate that these relate to conduit piston effects when the loss of gas pressure below a debris plug vibrates at shorter periods as the amplitude of the plug motion weakens.

  10. Loop formation of microtubules during gliding at high density

    NASA Astrophysics Data System (ADS)

    Liu, Lynn; Tüzel, Erkan; Ross, Jennifer L.

    2011-09-01

    The microtubule cytoskeleton, including the associated proteins, forms a complex network essential to multiple cellular processes. Microtubule-associated motor proteins, such as kinesin-1, travel on microtubules to transport membrane bound vesicles across the crowded cell. Other motors, such as cytoplasmic dynein and kinesin-5, are used to organize the cytoskeleton during mitosis. In order to understand the self-organization processes of motors on microtubules, we performed filament-gliding assays with kinesin-1 motors bound to the cover glass with a high density of microtubules on the surface. To observe microtubule organization, 3% of the microtubules were fluorescently labeled to serve as tracers. We find that microtubules in these assays are not confined to two dimensions and can cross one other. This causes microtubules to align locally with a relatively short correlation length. At high density, this local alignment is enough to create 'intersections' of perpendicularly oriented groups of microtubules. These intersections create vortices that cause microtubules to form loops. We characterize the radius of curvature and time duration of the loops. These different behaviors give insight into how crowded conditions, such as those in the cell, might affect motor behavior and cytoskeleton organization.

  11. Take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo (Galeopterus variegatus)

    PubMed Central

    Byrnes, Greg; Lim, Norman T.-L; Spence, Andrew J

    2008-01-01

    Arboreal animals negotiate a highly three-dimensional world that is discontinuous on many spatial scales. As the scale of substrate discontinuity increases, many arboreal animals rely on leaping or gliding locomotion between distant supports. In order to successfully move through their habitat, gliding animals must actively modulate both propulsive and aerodynamic forces. Here we examined the take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo (Galeopterus variegatus) using a custom-designed three-dimensional accelerometry system. We found that colugos increase the propulsive impulse to affect longer glides. However, we also found that landing forces are negatively associated with glide distance. Landing forces decrease rapidly as glide distance increases from the shortest glides, then level off, suggesting that the ability to reorient the aerodynamic forces prior to landing is an important mechanism to reduce velocity and thus landing forces. This ability to substantially alter the aerodynamic forces acting on the patagial wing in order to reorient the body is a key to the transition between leaping and gliding and allows gliding mammals to travel long distances between trees with reduced risk of injury. Longer glides may increase the access to distributed resources and reduce the exposure to predators in the canopy or on the forest floor. PMID:18252673

  12. Flight Modes in Migrating European Bee-Eaters: Heart Rate May Indicate Low Metabolic Rate during Soaring and Gliding

    PubMed Central

    Sapir, Nir; Wikelski, Martin; McCue, Marshall D.; Pinshow, Berry; Nathan, Ran

    2010-01-01

    Background Many avian species soar and glide over land. Evidence from large birds (mb>0.9 kg) suggests that soaring-gliding is considerably cheaper in terms of energy than flapping flight, and costs about two to three times the basal metabolic rate (BMR). Yet, soaring-gliding is considered unfavorable for small birds because migration speed in small birds during soaring-gliding is believed to be lower than that of flapping flight. Nevertheless, several small bird species routinely soar and glide. Methodology/Principal Findings To estimate the energetic cost of soaring-gliding flight in small birds, we measured heart beat frequencies of free-ranging migrating European bee-eaters (Merops apiaster, mb∼55 g) using radio telemetry, and established the relationship between heart beat frequency and metabolic rate (by indirect calorimetry) in the laboratory. Heart beat frequency during sustained soaring-gliding was 2.2 to 2.5 times lower than during flapping flight, but similar to, and not significantly different from, that measured in resting birds. We estimated that soaring-gliding metabolic rate of European bee-eaters is about twice their basal metabolic rate (BMR), which is similar to the value estimated in the black-browed albatross Thalassarche (previously Diomedea) melanophrys, mb∼4 kg). We found that soaring-gliding migration speed is not significantly different from flapping migration speed. Conclusions/Significance We found no evidence that soaring-gliding speed is slower than flapping flight in bee-eaters, contradicting earlier estimates that implied a migration speed penalty for using soaring-gliding rather than flapping flight. Moreover, we suggest that small birds soar and glide during migration, breeding, dispersal, and other stages in their annual cycle because it may entail a low energy cost of transport. We propose that the energy cost of soaring-gliding may be proportional to BMR regardless of bird size, as theoretically deduced by earlier studies

  13. Estimate of Rayleigh-to-Love wave ratio in the secondary microseism by colocated ring laser and seismograph

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Hadziioannou, Céline; Igel, Heiner; Wasserman, Joachim; Schreiber, Ulrich; Gebauer, André

    2015-04-01

    Using a colocated ring laser and an STS-2 seismograph, we estimate the ratio of Rayleigh-to-Love waves in the secondary microseism at Wettzell, Germany, for frequencies between 0.13 and 0.30 Hz. Rayleigh wave surface acceleration was derived from the vertical component of STS-2, and Love wave surface acceleration was derived from the ring laser. Surface wave amplitudes are comparable; near the spectral peak about 0.22 Hz, Rayleigh wave amplitudes are about 20% higher than Love wave amplitudes, but outside this range, Love wave amplitudes become higher. In terms of the kinetic energy, Rayleigh wave energy is about 20-35% smaller on average than Love wave energy. The observed secondary microseism at Wettzell thus consists of comparable Rayleigh and Love waves but contributions from Love waves are larger. This is surprising as the only known excitation mechanism for the secondary microseism, described by Longuet-Higgins (1950), is equivalent to a vertical force and should mostly excite Rayleigh waves.

  14. Deconvolution enhanced direction of arrival estimation using 1- and 3-component seismic arrays applied to ocean induced microseisms

    NASA Astrophysics Data System (ADS)

    Gal, M.; Reading, A. M.; Ellingsen, S. P.; Koper, K. D.; Burlacu, R.; Gibbons, S. J.

    2016-04-01

    Microseisms in the period of 2 - 10 seconds are generated in deep oceans and near coastal regions. It is common for microseisms from multiple sources to arrive at the same time at a given seismometer. It is therefore desirable to be able to measure multiple slowness vectors accurately. Popular ways to estimate the direction of arrival of ocean induced microseisms are the conventional (fk) or adaptive (Capon) beamformer. These techniques give robust estimates, but are limited in their resolution capabilities and hence do not always detect all arrivals. One of the limiting factors in determining direction of arrival with seismic arrays is the array response, which can strongly influence the estimation of weaker sources. In this work, we aim to improve the resolution for weaker sources and evaluate the performance of two deconvolution algorithms, Richardson-Lucy deconvolution and a new implementation of CLEAN-PSF. The algorithms are tested with 3 arrays of different aperture (ASAR, WRA and NORSAR) using 1 month of real data each and compared with the conventional approaches. We find an improvement over conventional methods from both algorithms and the best performance with CLEAN-PSF. We then extend the CLEAN-PSF framework to 3 components and evaluate 1 year of data from the Pilbara Seismic Array (PSAR) in north-west Australia. The 3 component CLEAN-PSF analysis is capable in resolving a previously undetected Sn phase.

  15. Applicability of an empirical law to predict significant sea-wave heights from microseisms along the Western Ligurian Coast (Italy)

    NASA Astrophysics Data System (ADS)

    Ferretti, Gabriele; Scafidi, Davide; Cutroneo, Laura; Gallino, Stefano; Capello, Marco

    2016-07-01

    The use of microseisms with appropriate predictive laws is a reliable method for estimating such sea-wave parameters as period and significant height. Through the use of opportune predictive laws calibrated with measurements obtained from wave buoys, it is possible to determine the significant height of the wave as a function of the spectral energy-content of the microseism. In this paper we will present a procedure that utilises microseisms recorded by a micro network of five seismic stations to predict the significant height of waves, and its uncertainty, along the western Ligurian coast (Italy). The calibration and validation of the procedure was performed using wave measurements obtained from a wave buoy off Capo Mele (Imperia, Italy) over a two and a half year period. The differences between the significant heights measured by the wave buoy and the empirical predictions were less than 10 cm (corresponding to 10% of the mean measured value) for 47% of the data and less than 20 cm (corresponding to 20% of the mean measured value) for 72%.

  16. Deconvolution enhanced direction of arrival estimation using one- and three-component seismic arrays applied to ocean induced microseisms

    NASA Astrophysics Data System (ADS)

    Gal, M.; Reading, A. M.; Ellingsen, S. P.; Koper, K. D.; Burlacu, R.; Gibbons, S. J.

    2016-07-01

    Microseisms in the period of 2-10 s are generated in deep oceans and near coastal regions. It is common for microseisms from multiple sources to arrive at the same time at a given seismometer. It is therefore desirable to be able to measure multiple slowness vectors accurately. Popular ways to estimate the direction of arrival of ocean induced microseisms are the conventional (fk) or adaptive (Capon) beamformer. These techniques give robust estimates, but are limited in their resolution capabilities and hence do not always detect all arrivals. One of the limiting factors in determining direction of arrival with seismic arrays is the array response, which can strongly influence the estimation of weaker sources. In this work, we aim to improve the resolution for weaker sources and evaluate the performance of two deconvolution algorithms, Richardson-Lucy deconvolution and a new implementation of CLEAN-PSF. The algorithms are tested with three arrays of different aperture (ASAR, WRA and NORSAR) using 1 month of real data each and compared with the conventional approaches. We find an improvement over conventional methods from both algorithms and the best performance with CLEAN-PSF. We then extend the CLEAN-PSF framework to three components (3C) and evaluate 1 yr of data from the Pilbara Seismic Array in northwest Australia. The 3C CLEAN-PSF analysis is capable in resolving a previously undetected Sn phase.

  17. Epoxy matrix composites filled with micro-sized LD sludge: wear characterization and analysis

    NASA Astrophysics Data System (ADS)

    Purohit, Abhilash; Satapathy, Alok

    2016-02-01

    Owing to the very high cost of conventional filler materials in polymer composites, exploring the possibility of using low cost minerals and industrial wastes for this purpose has become the need of the hour. In view of this, the present work includes the development and the wear performance evaluation of a new class of composites consisting of epoxy and microsized LD sludge. LD sludge or the Linz-Donawitz Sludge (LDS) are the fine solid particles recovered after wet cleaning of the gas emerging from LD convertors during steel making. Epoxy composites filled with different proportions (0, 5, 10, 15 and 20 wt %) of LDS are fabricated by conventional hand lay-up technique. Dry sliding wear trials are performed on the composite specimens under different test conditions as per ASTM G 99 following a design of experiment approach based on Taguchi's orthogonal arrays. The Taguchi approach leads to the recognition of most powerful variables that predominantly control the wear rate. This parametric analysis reveals that LDS content and sliding velocity affects the specific wear rate more significantly than normal load and sliding distance. Furthermore with increase in LDS content specific wear rate of the composite decreases for a constant sliding velocity. The sliding wear behavior of these composites under an extended range of test conditions is predicted by a model based on the artificial neural network (ANN).

  18. A micro-sized bio-solar cell for self-sustaining power generation.

    PubMed

    Lee, Hankeun; Choi, Seokheun

    2015-01-21

    Self-sustainable energy sources are essential for a wide array of wireless applications deployed in remote field locations. Due to their self-assembling and self-repairing properties, "biological solar (bio-solar) cells" are recently gaining attention for those applications. The bio-solar cell can continuously generate electricity from microbial photosynthetic and respiratory activities under day-night cycles. Despite the vast potential and promise of bio-solar cells, they, however, have not yet successfully been translated into commercial applications, as they possess persistent performance limitations and scale-up bottlenecks. Here, we report an entirely self-sustainable and scalable microliter-sized bio-solar cell with significant power enhancement by maximizing solar energy capture, bacterial attachment, and air bubble volume in well-controlled microchambers. The bio-solar cell has a ~300 μL single chamber defined by laser-machined poly(methyl methacrylate) (PMMA) substrates and it uses an air cathode to allow freely available oxygen to act as an electron acceptor. We generated a maximum power density of 0.9 mW m(-2) through photosynthetic reactions of cyanobacteria, Synechocystis sp. PCC 6803, which is the highest power density among all micro-sized bio-solar cells. PMID:25367739

  19. Numerical study of nanosecond laser interactions with micro-sized single droplets and sprays of xenon

    SciTech Connect

    Auguste, T.; Gaufridy de Dortan, F. de; Ceccotti, T.; Hergott, J. F.; Sublemontier, O.; Descamps, D.; Schmidt, M.

    2007-02-15

    We present a thorough numerical study on interactions of a nanosecond laser with micro-sized xenon droplets. We developed a code which allows simulation of laser interactions with a single droplet as well as a spray. We give a detailed description of the code, and we present results on the dynamics of a microplasma produced by irradiation of a single xenon droplet with a laser focused at peak vacuum intensity in the 5x10{sup 10}-5x10{sup 12} W/cm{sup 2} range. We find that the heating of the plasma depends dramatically on the laser parameters (duration, pulse shape, and intensity) on one hand, and on the droplet diameter on the other. We also present results obtained with a spray which show that the dynamics of the microplasmas is very sensitive to the position of the droplets in the interaction volume. The predictions of our model agree well with recent experimental observations performed on laser-produced plasma sources for extreme ultraviolet lithography. In particular, the postprocessing of our data with a sophisticated atomic physics code has allowed us to reproduce quite well the spectrum emitted in the extreme ultraviolet range by a xenon plasma generated by laser irradiation of a spray of droplets.

  20. Estimates of Rayleigh-to-Love wave ratio in microseisms by co-located Ring Laser and STS-2

    NASA Astrophysics Data System (ADS)

    Tanimoto, Toshiro; Hadziioannou, Céline; Igel, Heiner; Wassermann, Joachim; Schreiber, Ulrich; Gebauer, André

    2015-04-01

    In older studies of microseisms (seismic noise), it was often assumed that microseisms, especially the secondary microseisms (0.1-0.3 Hz), mainly consist of Rayleigh waves. However, it has become clear that there exists a large amount of Love-wave energy mixed in it (e.g., Nishida et al., 2008). However, its confirmation is not necessarily straightforward and often required an array of seismographs. In this study, we take advantage of two co-located instruments, a Ring Laser and an STS-2 type seismograph, at Wettzell (WET), Germany (Schreiber et al., 2009). The Ring Laser records rotation (its vertical component) and is thus only sensitive to Love waves. The vertical component of STS-2 seismograph is only sensitive to Rayleigh waves. Therefore, a combination of the two instruments provides a unique opportunity to separate Rayleigh waves and Love waves in microseisms. The question we address in this paper is the ratio of Rayleigh waves to Love waves in microseisms. For both instruments, we analyze data from 2009 to 2014. Our basic approach is to create stacked vertical acceleration spectra for Rayleigh waves from STS-2 and stacked transverse acceleration spectra for Love waves from Ring Laser. The two spectra at Earth's surface can then be compared directly by their amplitudes. The first step in our analysis is a selection of time portions (each six-hour long) that are least affected by earthquakes. We do this by examining the GCMT (Global Centroid Moment Tensor) catalogue and also checking the PSDs for various frequency ranges. The second step is to create stacked (averaged) Fourier spectra from those selected time portions. The key is to use the same time portions for the STS-2 and the Ring Laser data so that the two can be directly compared. The vertical spectra from STS-2 are converted to acceleration spectra. The Ring Laser rotation spectra are first obtained in the unit of radians/sec (rotation rate). But as the Ring Laser spectra are dominated by fundamental

  1. Effects of Glide Path on the Centering Ability and Preparation Time of Two Reciprocating Instruments

    PubMed Central

    Coelho, Marcelo Santos; Fontana, Carlos Eduardo; Kato, Augusto Shoji; de Martin, Alexandre Sigrist; da Silveira Bueno, Carlos Eduardo

    2016-01-01

    Introduction: The aim of this in vitro study was to evaluate the effects of establishing glide path on the centering ability and preparation time of two single-file reciprocating systems in mesial root canals of mandibular molars. Methods and Materials: Sixty extracted mandibular molars with curvatures of 25-39 degrees and separate foramina for the mesiobuccal and mesiolingual canals, were divided into four groups (n=15); WaveOne+glide path; WaveOne; Reciproc+glide path and Reciproc. Non-patent canals were excluded and only one canal in each tooth was instrumented. A manual glide path was established in first and third groups with #10, 15 and 20 hand K-files. Preparation was performed with reciprocating in-and-out motion, with a 3-4 mm amplitude and slight apical pressure. Initial and final radiographs were taken to analyze the amount of dentin removed in the instrumented canals. The radiographs were superimposed with an image editing software and examined to assess discrepancies at 3-, 6- and 9-mm distances from the apex. The Kruskal-Wallis test was used for statistical analysis. The level of significance was set at 0.05. Results: Preparation in groups without glide paths was swifter than the other groups (P=0.001). However, no difference was observed regarding centering ability. Conclusion: Establishing a glide path increased the total instrumentation time for preparing curved canals with WaveOne and Reciproc instruments. Glide path had no influence on the centering ability of these systems. PMID:26843875

  2. Identifying seismic noise sources and their amplitude from P wave microseisms.

    NASA Astrophysics Data System (ADS)

    Neale, Jennifer; Harmon, Nicholas; Srokosz, Meric

    2016-04-01

    Understanding sources of seismic noise is important for a range of applications including seismic imagery, time-lapse, and climate studies. For locating sources from seismic data, body waves offer an advantage over surface waves because they can reveal the distance to the source as well as direction. Studies have found that body waves do originate from regions predicted by models (Obrebski et al., 2013), where wave interaction intensity and site effect combine to produce the source (Ardhuin & Herbers, 2013). Here, we undertake a quantitative comparison between observed body wave microseisms and modelled sources- in terms of location, amplitude, and spectral shape- with the aim of understanding how well sources are observed and potentially what they reveal about the underlying ocean wavefield. We used seismic stations from the Southern California Seismic Network, and computed beamformer output as a function of time, frequency, slowness and azimuth. During winter months (October - mid March) the dominant arrivals at frequencies 0.18-0.22 Hz were P waves that originated from the North Pacific, whilst arrivals from the North Atlantic dominated at slightly lower frequencies of 0.16-0.18 Hz. Based on this, we chose to focus on P waves during winter, and back-projected the beamformer energy onto a global grid using P wave travel timetables (following Gerstoft et al., 2008). We modelled the seismic sources using Wavewatch III and site effect coefficients calculated following Ardhuin and Herbers (2013). We output the beamformer and the modelled sources on a 2° global grid averaged over 6 hour periods from September 2012 to September 2014, at seismic frequencies of 0.06 to 0.3 Hz. We then integrated the spectra over the full frequency range. Here we focus on results from the first winter in the North Pacific. Preliminary results indicate that the logarithm of the modelled source and the logarithm of the beamformer output are well described by a two-term exponential model

  3. Integrated Information and Prospects for Gliding Mechanism of the Pathogenic Bacterium Mycoplasma pneumoniae

    PubMed Central

    Miyata, Makoto; Hamaguchi, Tasuku

    2016-01-01

    Mycoplasma pneumoniae forms a membrane protrusion at a cell pole and is known to adhere to solid surfaces, including animal cells, and can glide on these surfaces with a speed up to 1 μm per second. Notably, gliding appears to be involved in the infectious process in addition to providing the bacteria with a means of escaping the host's immune systems. However, the genome of M. pneumoniae does not encode any of the known genes found in other bacterial motility systems or any conventional motor proteins that are responsible for eukaryotic motility. Thus, further analysis of the mechanism underlying M. pneumoniae gliding is warranted. The gliding machinery formed as the membrane protrusion can be divided into the surface and internal structures. On the surface, P1 adhesin, a 170 kDa transmembrane protein forms an adhesin complex with other two proteins. The internal structure features a terminal button, paired plates, and a bowl (wheel) complex. In total, the organelle is composed of more than 15 proteins. By integrating the currently available information by genetics, microscopy, and structural analyses, we have suggested a working model for the architecture of the organelle. Furthermore, in this article, we suggest and discuss a possible mechanism of gliding based on the structural model, in which the force generated around the bowl complex transmits through the paired plates, reaching the adhesin complex, resulting in the repeated catch of sialylated oligosaccharides on the host surface by the adhesin complex. PMID:27446003

  4. Influence of a glide path on the dentinal crack formation of ProTaper Next system

    PubMed Central

    Uzunoğlu, Emel

    2015-01-01

    Objectives The aim was to evaluate dentinal crack formation after root canal preparation with ProTaper Next system (PTN) with and without a glide path. Materials and Methods Forty-five mesial roots of mandibular first molars were selected. Fifteen teeth were left unprepared and served as controls. The experimental groups consist of mesiobuccal and mesiolingual root canals of remaining 30 teeth, which were divided into 2 groups (n = 15): Group PG/PTN, glide path was created with ProGlider (PG) and then canals were shaped with PTN system; Group PTN, glide path was not prepared and canals were shaped with PTN system only. All roots were sectioned perpendicular to the long axis at 1, 2, 3, 4, 6, and 8 mm from the apex, and the sections were observed under a stereomicroscope. The presence/absence of cracks was recorded. Data were analyzed with chi-square tests with Yates correction. Results There were no significant differences in crack formation between the PTN with and without glide path preparation. The incidence of cracks observed in PG/PTN and PTN groups was 17.8% and 28.9%, respectively. Conclusions The creation of a glide path with ProGlider before ProTaper Next rotary system did not influence dentinal crack formation in root canals. PMID:26587414

  5. Dislocation dynamics simulations of interactions between gliding dislocations and radiation induced prismatic loops in zirconium

    NASA Astrophysics Data System (ADS)

    Drouet, Julie; Dupuy, Laurent; Onimus, Fabien; Mompiou, Frédéric; Perusin, Simon; Ambard, Antoine

    2014-06-01

    The mechanical behavior of Pressurized Water Reactor fuel cladding tubes made of zirconium alloys is strongly affected by neutron irradiation due to the high density of radiation induced dislocation loops. In order to investigate the interaction mechanisms between gliding dislocations and loops in zirconium, a new nodal dislocation dynamics code, adapted to Hexagonal Close Packed metals, has been used. Various configurations have been systematically computed considering different glide planes, basal or prismatic, and different characters, edge or screw, for gliding dislocations with -type Burgers vectors. Simulations show various interaction mechanisms such as (i) absorption of a loop on an edge dislocation leading to the formation of a double super-jog, (ii) creation of a helical turn, on a screw dislocation, that acts as a strong pinning point or (iii) sweeping of a loop by a gliding dislocation. It is shown that the clearing of loops is more favorable when the dislocation glides in the basal plane than in the prismatic plane explaining the easy dislocation channeling in the basal plane observed after neutron irradiation by transmission electron microscopy.

  6. Polycomb Controls Gliogenesis by Regulating the Transient Expression of the Gcm/Glide Fate Determinant

    PubMed Central

    Diebold, Celine; Van de Bor, Véronique; Schuettengruber, Bernd; González, Inma; Busturia, Ana; Cavalli, Giacomo; Giangrande, Angela

    2012-01-01

    The Gcm/Glide transcription factor is transiently expressed and required in the Drosophila nervous system. Threshold Gcm/Glide levels control the glial versus neuronal fate choice, and its perdurance triggers excessive gliogenesis, showing that its tight and dynamic regulation ensures the proper balance between neurons and glia. Here, we present a genetic screen for potential gcm/glide interactors and identify genes encoding chromatin factors of the Trithorax and of the Polycomb groups. These proteins maintain the heritable epigenetic state, among others, of HOX genes throughout development, but their regulatory role on transiently expressed genes remains elusive. Here we show that Polycomb negatively affects Gcm/Glide autoregulation, a positive feedback loop that allows timely accumulation of Gcm/Glide threshold levels. Such temporal fine-tuning of gene expression tightly controls gliogenesis. This work performed at the levels of individual cells reveals an undescribed mode of Polycomb action in the modulation of transiently expressed fate determinants and hence in the acquisition of specific cell identity in the nervous system. PMID:23300465

  7. The statistics of the time segments of low-frequency microseisms: Trends and synchronization

    NASA Astrophysics Data System (ADS)

    Lyubushin, A. A.

    2010-06-01

    The problem of identifying the effects of synchronization in the parameters of low-frequency microseismic noise from the data of 77 stations belonging to the F-net broadband seismograph network in Japan for the period from the beginning of 1997 through August, 2009 is considered. The vertical components measured initially with a sampling rate of one second and subsequently converted into the signals sampled at 1 minute intervals by means of averaging and decimation are used in the analysis. Six statistics are taken as the parameters: the support width of the multifractal singularity spectrum; the generalized Hurst exponent; the asymmetry coefficient of the spectrum of singularity; the logarithmic variance; the spectral exponent; and the linear predictability index. These parameters are calculated from the realizations contained within consecutive daily time intervals. When using the moving time window with a width of one year for evaluating the multiple correlation, the daily variations in the median values of the statistics of the noise measured at five spatial clusters of stations exhibit a stable increase in the synchronization not long before the Hokkaido earthquake (September 25, 2003; M = 8.3), subsequently passing to the new level of high synchronization. Based on the analysis of the trends in the index of linear predictability it turned out possible to estimate the beginning of the enhancement in the synchronization with rather high accuracy as the middle of 2002. The effect revealed for the variations in the different parameters of microseisms is an independent argument for the earlier conclusion about the synchronization in the field of the microseismic noise on the Japan Islands.

  8. Waste generation and utilisation in micro-sized furniture-manufacturing enterprises in Turkey.

    PubMed

    Top, Y

    2015-01-01

    The number of small-scale businesses within most national economies is generally high, especially in developing countries. Often these businesses have a weak economic status and limited environmental awareness. The type and amount of waste produced, and the recycling methods adopted by these businesses during their operation can have negative effects on the environment. This study investigated the types of waste generated and the recycling methods adopted in micro-sized enterprises engaged in the manufacture of furniture. An assessment was also made of whether the characteristics of the enterprise had any effect on the waste recycling methods that were practised. A survey was conducted of 31 enterprises in the furniture industry in Gumushane province, Turkey, which is considered a developing economy. Surveys were undertaken via face-to-face interviews. It was found that medium-density fibreboard (MDF), and to a lesser extent, chipboard, were used in the manufacture of furniture, and two major types of waste in the form of fine dust and small fragments of board are generated during the cutting of these boards. Of the resulting composite board waste, 96.9% was used for heating homes and workplaces, where it was burnt under conditions of incomplete combustion. Enterprises were found to have adopted other methods to utilise their wastes in addition to using them as fuel. Such enterprises include those operating from a basement or first floor of a building in the cities, those continuing production throughout the year, those in need for capital and those enterprises not operating a dust-collection system. PMID:25453314

  9. A quantitative evaluation of the dynamic cathodoluminescence contrast of gliding dislocations in semiconductor crystals

    NASA Astrophysics Data System (ADS)

    Vasnyov, S.; Schreiber, J.; Hoering, L.

    2004-01-01

    Dark cathodoluminescence (CL) defect contrasts observed in CL video movies taken on GaAs and ZnO samples disclose the intrinsic recombination properties of glide dislocations during their slip motion. This way, the kinematical SEM CL microscopy provides, for the first time, direct information on the possible relationship between the dynamics and electronic activity of glide dislocations as expected from structural alterations or kink processes related to defect movement. The dark CL defect contrasts observed for various dislocation types in both materials indicate defect-bound non-radiative excess carrier recombination. Quantitative CL contrast analysis is performed to discover differences in the recombination strength of distinct dislocation structures resulting from the type and dynamic state of the glide dislocations studied.

  10. Investigations of Lateral Stability of a Glide Bomb Using Automatic Control Having No Time Lag

    NASA Technical Reports Server (NTRS)

    Sponder, E. W.

    1950-01-01

    The investigation of the lateral stability of an automatically controlled glide bomb led also to the attempt of clarifying the influence of a phugoid oscillation or of any general longitudinal oscillation on the lateral stability of a glide bomb. Under the assumption that its period of oscillation considerably exceeds the rolling and yawing oscillation and that c(sub a) is, at least in sections, practically constant, the result of this test is quite simple. It becomes clear that the influence of the phugoid oscillation may be replaced by suitable variation of the rolling-yawing moment on a rectilinear flight path instead of the phugoid oscillation. If the flying weight of the glide bomb of unchanged dimensions is increased, an increase of the flight velocity will be more favorable than an increase of the lift coefficient. The arrangement of the control permits lateral stability to be achieved in every case; a minimum rolling moment due to sideslip proves of great help.

  11. Reprint of “Prospects for the gliding mechanism of Mycoplasma mobile”.

    PubMed

    Miyata, Makoto; Hamaguchi, Tasuku

    2015-12-01

    Mycoplasma mobile forms gliding machinery at a cell pole and glides continuously in the direction of the cell pole at up to 4.5 μm per second on solid surfaces such as animal cells. This motility system is not related to those of any other bacteria or eukaryotes. M. mobile uses ATP energy to repeatedly catch, pull, and release sialylated oligosaccharides on host cells with its approximately 50-nm long legs. The gliding machinery is a large structure composed of huge surface proteins and internal jellyfish-like structure. This system may have developed from an accidental combination between an adhesin and a rotary ATPase, both of which are essential for the adhesive parasitic life of Mycoplasmas. PMID:26711226

  12. The collapse of stacking fault tetrahedra by interactions with gliding dislocations.

    SciTech Connect

    Matsukawa, Yoshitaka; Osetskiy, Yury N; Stocks, George Malcolm; Zinkle, Steven J

    2005-01-01

    The collapse of stacking-fault tetrahedra (SFT) by gliding dislocations was observed in in situ straining experiments in a transmission electron microscope (TEM). A stacking-fault tetrahedron was collapsed by intersection with a gliding perfect dislocation: only the base portion divided by the gliding plane of the dislocation annihilated, while the apex portion remained intact. As a result of analysis on evolution of atom configuration induced by intersection with perfect dislocation in SFT, it was found that an unusual atom configuration inevitably appeared in one of the ledges formed on stacking-fault planes, which is traditionally called I-ledge: the atoms on adjacent (111) planes were overlapping each other. The overlapping configuration provides a strong repulsive force, being a conceivable driving force to induce a chain reaction of atom displacements that collapses the SFT base portion.

  13. Do physicochemical sediment variables and their soft sediment macrofauna differ among microsize coastal lagoons with forested and urbanised catchments?

    NASA Astrophysics Data System (ADS)

    Mikac, K. M.; Maher, W. A.; Jones, A. R.

    2007-03-01

    Microsize intermittently open and closed coastal lagoons are a common feature of the coast of southern New South Wales, in southeast Australia. Many of these lagoons are undergoing development and urbanisation of their catchments, leading to concern about their ecological health. Consequently, it was hypothesised that lagoons with urbanised catchments should hav e finer, more contaminated sediments and fewer macrofaunal taxa (represented by opportunistic taxa) than lagoons that have undeveloped, forested catchments. To test these hypotheses, five lagoons with catchments dominated by either native forest or urban development were compared with respect to their sediment composition (i.e. sediment grain size, trace metal concentrations, organic carbon and nutrients) and soft sediment macrofaunal assemblages in the Batemans Bay region of southeast Australia. Using a nested design without temporal replication, replicate core samples were taken from sampling stations nested within lagoons that were nested within catchment type. Univariate and multivariate statistical analyses were used to test for significant differences and dissimilarities between catchment types and among lagoons. Of all the abiotic and biotic variables measured, only total nitrogen showed a difference between the two catchment types. Thus providing support to refute the explanatory model that urbanisation had negatively affected the sedimentary environment and macrofaunal composition of these microsize coastal lagoons. In contrast, differences among lagoons were usually significant with differences between the two forested lagoons, North Head and Acheron lagoon, being particularly large for assemblage composition and the abundance of some taxa; this variation may, potentially, obscure any effects of urbanisation. In addition, the information collected in this study provides a basic understanding of the physicochemical and biological aspects of microsize coastal lagoons in southeast Australia. Such

  14. Cruising the rain forest floor: butterfly wing shape evolution and gliding in ground effect.

    PubMed

    Cespedes, Ann; Penz, Carla M; DeVries, Philip J

    2015-05-01

    Flight is a key innovation in the evolutionary success of insects and essential to dispersal, territoriality, courtship and oviposition. Wing shape influences flight performance and selection likely acts to maximize performance for conducting essential behaviours that in turn results in the evolution of wing shape. As wing shape also contributes to fitness, optimal shapes for particular flight behaviours can be assessed with aerodynamic predictions and placed in an ecomorphological context. Butterflies in the tribe Haeterini (Nymphalidae) are conspicuous members of understorey faunas in lowland Neotropical forests. Field observations indicate that the five genera in this clade differ in flight height and behaviour: four use gliding flight at the forest floor level, and one utilizes flapping flight above the forest floor. Nonetheless, the association of ground level gliding flight behaviour and wing shape has never been investigated in this or any other butterfly group. We used landmark-based geometric morphometrics to test whether wing shapes in Haeterini and their close relatives reflected observed flight behaviours. Four genera of Haeterini and some distantly related Satyrinae showed significant correspondence between wing shape and theoretical expectations in performance trade-offs that we attribute to selection for gliding in ground effect. Forewing shape differed between sexes for all taxa, and male wing shapes were aerodynamically more efficient for gliding flight than corresponding females. This suggests selection acts differentially on male and female wing shapes, reinforcing the idea that sex-specific flight behaviours contribute to the evolution of sexual dimorphism. Our study indicates that wing shapes in Haeterini butterflies evolved in response to habitat-specific flight behaviours, namely gliding in ground effect along the forest floor, resulting in ecomorphological partitions of taxa in morphospace. The convergent flight behaviour and wing morphology

  15. Tensile response of passivated films with climb-assisted dislocation glide

    NASA Astrophysics Data System (ADS)

    Ayas, C.; Deshpande, V. S.; Geers, M. G. D.

    2012-09-01

    The tensile response of single crystal films passivated on two sides is analysed using climb enabled discrete dislocation plasticity. Plastic deformation is modelled through the motion of edge dislocations in an elastic solid with a lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and dislocation annihilation incorporated through a set of constitutive rules. The dislocation motion in the films is by glide-only or by climb-assisted glide whereas in the surface passivation layers dislocation motion occurs by glide-only and penalized by a friction stress. For realistic values of the friction stress, the size dependence of the flow strength of the oxidised films was mainly a geometrical effect resulting from the fact that the ratio of the oxide layer thickness to film thickness increases with decreasing film thickness. However, if the passivation layer was modelled as impenetrable, i.e. an infinite friction stress, the plastic hardening rate of the films increases with decreasing film thickness even for geometrically self-similar specimens. This size dependence is an intrinsic material size effect that occurs because the dislocation pile-up lengths become on the order of the film thickness. Counter-intuitively, the films have a higher flow strength when dislocation motion is driven by climb-assisted glide compared to the case when dislocation motion is glide-only. This occurs because dislocation climb breaks up the dislocation pile-ups that aid dislocations to penetrate the passivation layers. The results also show that the Bauschinger effect in passivated thin films is stronger when dislocation motion is climb-assisted compared to films wherein dislocation motion is by glide-only.

  16. Aerodynamic performance due to forewing and hindwing interaction in gliding dragonfly flight

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Lu, Xi-Yun

    2009-07-01

    Aerodynamic performance due to forewing and hindwing interaction in gliding dragonfly flight has been studied using a multiblock lattice Boltzmann method. We find that the interactions between forewing and hindwing effectively enhance the total lift force and reduce the drag force on the wings compared to two independent wings. The interaction mechanism may be associated with the triangular camber effect by modulating the relative arrangement of the forewing and hindwing. The results obtained in this Brief Report provide physical insight into the understanding of aerodynamic behaviors for gliding dragonfly flight.

  17. The Role of Incision and Sedimentation in Continental Gravity Gliding - Insight from Numerical Modelling

    NASA Astrophysics Data System (ADS)

    Riad, H.; Messager, G.; Nivihre, B.

    2010-12-01

    Large scale gravity gliding are usually observed in deltas and passive margins. They imply the rigid translation of a body down a slope, with coeval upslope extension and downslope contraction. Displacement vectors are parallel to a buried detachment plane gently dipping basinward (1-5°). Field examples suggest that gravity gliding could be found in continental domains but contrary to oceanic environments, upslope sedimentation and pore fluid overpressure do not play a major role. These lacks must be compensated. This study investigates mechanisms generating gravity gliding in a continental domains through the use of a two-dimensional (2D) finite-element model and a 2D analytical failure analysis. We focus on the role of tectonic uplifts and the subsequent fluvial incision and sedimentation at the toes of the slopes. The geometries of the numerical models are based on a field example in the Andean foothills of Argentina. Gravity gliding occurs along the long limb of an asymmetric crustal-scale anticline, above a 1000 m depth salt layers. The numerical models simulate the deformations and estimate quantitatively the circumstances under which failure at the head and toe of the frictional-plastic sedimentary cover initiates. Analytical solutions give simplified approximation of the numerical results taking into account many configurations with various values of the incision, sedimentation, internal friction angle and thickness of the décollement layer. The principal effect of the incision and sedimentation is to reduce and strengthen the downslope resistance to the contractional failure. Consequently, the magnitude of the critical slope for which the gravity gliding initiates, is reduced by the incision and is increased by the sedimentation. Results show that large-scale gravity gliding can be found in continental domains as a consequence of tectonic uplifts and where overburden thickness is lower than 2000 m. Incision facilitates and localizes the gliding

  18. Gliding Text: A New Aid to Improve the Reading Performance of Poor Readers by Subconscious Gaze Control.

    ERIC Educational Resources Information Center

    Krischer, C. C.; And Others

    1994-01-01

    People with reading difficulties experience automatic gaze guidance when using gliding text (subtitles). Reading exercises with gliding text eliminated reading difficulties for 21 second graders in 24 15-minute sessions. Mean reading speed increased from 10 to 24 words per minute. (SK)

  19. Toxicity of nano- and micro-sized silver particles in human hepatocyte cell line L02

    NASA Astrophysics Data System (ADS)

    Liu, Pengpeng; Guan, Rongfa; Ye, Xingqian; Jiang, Jiaxin; Liu, Mingqi; Huang, Guangrong; Chen, Xiaoting

    2011-07-01

    Silver nanoparticles (Ag NPs) previously classified as antimicrobial agents have been widely used in consumers and industrial products, especially food storage material. Ag NPs used as antimicrobial agents may be found in liver. Thus, examination of the ability of Ag NPs to penetrate the liver is warranted. The aim of the study was to determine the optimal viability assay for using with Ag NPs in order to assess their toxicity to liver cells. For toxicity evaluations, cellular morphology, mitochondrial function (3-(4, 5-dimethylazol-2-yl)-2, 5-diphenyl-tetrazolium bromide, MTT assay), membrane leakage of lactate dehydrogenase (lactate dehydrogenase, LDH release assay), Oxidative stress markers (malonaldehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD)), DNA damage (single cell gel eletrophoresis, SCGE assay), and protein damage were assessed under control and exposed conditions (24 h of exposure). The results showed that mitochondrial function decreased significantly in cells exposed to Ag NPs at 25 μg·mL-1. LDH leakage significantly increased in cells exposed to Ag NPs (>= 25 μg mL-1) while micro-sized silver particles tested displayed LDH leakage only at higher doses (100 μg·mL-1). The microscopic studies demonstrated that nanoparticle-exposed cells at higher doses became abnormal in size, displaying cellular shrinkage, and an acquisition of an irregular shape. Due to toxicity of silver, further study conducted with reference to its oxidative stress. The results exhibited significant depletion of GSH level, increase in SOD levels and lead to lipid peroxidation, which suggested that cytotoxicity of Ag NPs in liver cells might be mediated through oxidative stress. The results demonstrates that Ag NPs lead to cellular morphological modifications, LDH leakage, mitochondrial dysfunction, and cause increased generation of ROS, depletion of GSH, lipid peroxidation, oxidative DNA damage and protein damage. Though the exact mechanism behind Ag NPs

  20. Directed Binding of Gliding Bacterium, Mycoplasma mobile, Shown by Detachment Force and Bond Lifetime

    PubMed Central

    Tanaka, Akihiro; Nakane, Daisuke; Mizutani, Masaki; Nishizaka, Takayuki

    2016-01-01

    ABSTRACT Mycoplasma mobile, a fish-pathogenic bacterium, features a protrusion that enables it to glide smoothly on solid surfaces at a velocity of up to 4.5 µm s−1 in the direction of the protrusion. M. mobile glides by a repeated catch-pull-release of sialylated oligosaccharides fixed on a solid surface by hundreds of 50-nm flexible “legs” sticking out from the protrusion. This gliding mechanism may be explained by a possible directed binding of each leg with sialylated oligosaccharides, by which the leg can be detached more easily forward than backward. In the present study, we used a polystyrene bead held by optical tweezers to detach a starved cell at rest from a glass surface coated with sialylated oligosaccharides and concluded that the detachment force forward is 1.6- to 1.8-fold less than that backward, which may be linked to a catch bond-like behavior of the cell. These results suggest that this directed binding has a critical role in the gliding mechanism. PMID:27353751

  1. Use of glide-ins in CMS for production and analysis

    SciTech Connect

    Bradley, D.; Gutsche, O.; Hahn, K.; Holzman, B.; Padhi, S.; Pi, H.; Spiga, D.; Sfiligoi, I.; Vaandering, E.; Wurthwein, F.; /UC, San Diego

    2010-01-01

    With the evolution of various grid federations, the Condor glide-ins represent a key feature in providing a homogeneous pool of resources using late-binding technology. The CMS collaboration uses the glide-in based Workload Management System, glideinWMS, for production (ProdAgent) and distributed analysis (CRAB) of the data. The Condor glide-in daemons traverse to the worker nodes, submitted via Condor-G. Once activated, they preserve the Master-Worker relationships, with the worker first validating the execution environment on the worker node before pulling the jobs sequentially until the expiry of their lifetimes. The combination of late-binding and validation significantly reduces the overall failure rate visible to CMS physicists. We discuss the extensive use of the glideinWMS since the computing challenge, CCRC-08, in order to prepare for the forthcoming LHC data-taking period. The key features essential to the success of large-scale production and analysis on CMS resources across major grid federations, including EGEE, OSG and NorduGrid are outlined. Use of glide-ins via the CRAB server mechanism and ProdAgent, as well as first hand experience of using the next generation CREAM computing element within the CMS framework is discussed.

  2. An In Vitro Comparison of Root Canal Transportation by Reciproc File With and Without Glide Path

    PubMed Central

    Nazarimoghadam, Kiumars; Daryaeian, Mohammad; Ramazani, Nahid

    2014-01-01

    Objective: The aim of ideal canal preparation is to prevent iatrogenic aberrations such as transportation. The aim of this study was to evaluate the root canal transportation by Reciproc file with and without glide path. Materials and Methods: Thirty acrylic-resin blocks with a curvature of 60° and size#10 (2% taper) were assigned into two groups (n= 15). In group 1, the glide path was performed using stainless steel k-files size#10 and 15 at working length In group 2, canals were prepared with Reciproc file system at working length. By using digital imaging software (AutoCAD 2008), the pre-instrumentation and post-instrumentation digital images were superimposed over, taking the landmarks as reference points. Then the radius of the internal and external curve of the specimens was calculated at three α, β and γ points (1mm to apex as α, 3mm to apex as β, and 5mm to apex as γ). The data were statically analyzed using the independent T-test and Mann-Whitney U test by SPSS version 16. Results: Glide path was found significant for only external curve in the apical third of the canal; that is, 5mm to apex (P=0.005). But in the other third, canal modification was not significant (P> 0.008). Conclusion: Canal transportation in the apical third of the canal seems to be significantly reduced when glide path is performed using reciprocating files. PMID:25628682

  3. Evaluation of the GlideScope Direct: A New Video Laryngoscope for Teaching Direct Laryngoscopy

    PubMed Central

    Viernes, Darwin; Goldman, Allan J.; Galgon, Richard E.; Joffe, Aaron M.

    2012-01-01

    Background. Teaching direct laryngoscopy is limited by the inability of the instructor to simultaneously view the airway with the laryngoscopist. Our primary aim is to report our initial use of the GlideScope Direct, a video-enabled, Macintosh laryngoscope intended primarily as a training tool in direct laryngoscopy. Methods. The GlideScope Direct was made available to anyone who planned on performing direct laryngoscopy as the primary technique for intubation. Novices were those who had performed <30 intubations. Results. The GlideScope Direct was used 123 times as primarily a direct laryngoscope while the instructor viewed the intubation on the monitor. It was highly successful as a direct laryngoscope (93% success). Salvage by indirect laryngoscopy occurred in 7/9 remaining patients without changing equipment. Novices performed 28 intubations (overall success rate of 79%). In 6 patients, the instructor took over and successfully intubated the patient. Instructors used the video images to guide the operator in 16 (57%) of those patients. Seven different instructors supervised the 28 novices, all of who subjectively felt advantaged by having the laryngoscopic view available. Conclusions. The GlideScope Direct functions similarly to a Macintosh laryngoscope and provides the instructor subjective reassurance, while providing the ability to guide the trainee laryngoscopist. PMID:22778728

  4. Use of glide-ins in CMS for production and analysis

    NASA Astrophysics Data System (ADS)

    Bradley, D.; Gutsche, O.; Hahn, K.; Holzman, B.; Padhi, S.; Pi, H.; Spiga, D.; Sfiligoi, I.; Vaandering, E.; Würthwein, F.; CMS Offline Computing Projects

    2010-04-01

    With the evolution of various grid federations, the Condor glide-ins represent a key feature in providing a homogeneous pool of resources using late-binding technology. The CMS collaboration uses the glide-in based Workload Management System, glideinWMS, for production (ProdAgent) and distributed analysis (CRAB) of the data. The Condor glide-in daemons traverse to the worker nodes, submitted via Condor-G. Once activated, they preserve the Master-Worker relationships, with the worker first validating the execution environment on the worker node before pulling the jobs sequentially until the expiry of their lifetimes. The combination of late-binding and validation significantly reduces the overall failure rate visible to CMS physicists. We discuss the extensive use of the glideinWMS since the computing challenge, CCRC-08, in order to prepare for the forthcoming LHC data-taking period. The key features essential to the success of large-scale production and analysis on CMS resources across major grid federations, including EGEE, OSG and NorduGrid are outlined. Use of glide-ins via the CRAB server mechanism and ProdAgent, as well as first hand experience of using the next generation CREAM computing element within the CMS framework is discussed.

  5. Flavobacterium columnare type IX secretion system mutations result in defects in gliding motility and virulence

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: The gliding bacterium Flavobacterium columnare causes columnaris disease in wild and aquaculture-reared freshwater fish. The mechanisms responsible for columnaris disease are not known. The related bacterium Flavobacterium johnsoniae uses a type IX secretion system (T9SS) to secrete enzy...

  6. Ancient phylogenetic divergence of the enigmatic African rodent Zenkerella and the origin of anomalurid gliding

    PubMed Central

    Fernández, David; Sallam, Hesham M.; Cronin, Drew T.; Esara Echube, José Manuel

    2016-01-01

    The “scaly-tailed squirrels” of the rodent family Anomaluridae have a long evolutionary history in Africa, and are now represented by two gliding genera (Anomalurus and Idiurus) and a rare and obscure genus (Zenkerella) that has never been observed alive by mammalogists. Zenkerella shows no anatomical adaptations for gliding, but has traditionally been grouped with the glider Idiurus on the basis of craniodental similarities, implying that either the Zenkerella lineage lost its gliding adaptations, or that Anomalurus and Idiurus evolved theirs independently. Here we present the first nuclear and mitochondrial DNA sequences of Zenkerella, based on recently recovered whole-body specimens from Bioko Island (Equatorial Guinea), which show unambiguously that Zenkerella is the sister taxon of Anomalurus and Idiurus. These data indicate that gliding likely evolved only once within Anomaluridae, and that there were no subsequent evolutionary reversals. We combine this new molecular evidence with morphological data from living and extinct anomaluromorph rodents and estimate that the lineage leading to Zenkerella has been evolving independently in Africa since the early Eocene, approximately 49 million years ago. Recently discovered fossils further attest to the antiquity of the lineage leading to Zenkerella, which can now be recognized as a classic example of a “living fossil,” about which we know remarkably little. The osteological markers of gliding are estimated to have evolved along the stem lineage of the Anomalurus–Idiurus clade by the early Oligocene, potentially indicating that this adaptation evolved in response to climatic perturbations at the Eocene–Oligocene boundary (∼34 million years ago). PMID:27602286

  7. The Effect of Depth on Drag During the Streamlined Glide: A Three-Dimensional CFD Analysis.

    PubMed

    Novais, Maria L; Silva, António J; Mantha, Vishveshwar R; Ramos, Rui J; Rouboa, Abel I; Vilas-Boas, J Paulo; Luís, Sérgio R; Marinho, Daniel A

    2012-06-01

    The aim of this study was to analyze the effects of depth on drag during the streamlined glide in swimming using Computational Fluid Dynamics. The Computation Fluid Dynamic analysis consisted of using a three-dimensional mesh of cells that simulates the flow around the considered domain. We used the K-epsilon turbulent model implemented in the commercial code Fluent(®) and applied it to the flow around a three-dimensional model of an Olympic swimmer. The swimmer was modeled as if he were gliding underwater in a streamlined prone position, with hands overlapping, head between the extended arms, feet together and plantar flexed. Steady-state computational fluid dynamics analyses were performed using the Fluent(®) code and the drag coefficient and the drag force was calculated for velocities ranging from 1.5 to 2.5 m/s, in increments of 0.50m/s, which represents the velocity range used by club to elite level swimmers during the push-off and glide following a turn. The swimmer model middle line was placed at different water depths between 0 and 1.0 m underwater, in 0.25m increments. Hydrodynamic drag decreased with depth, although after 0.75m values remained almost constant. Water depth seems to have a positive effect on reducing hydrodynamic drag during the gliding. Although increasing depth position could contribute to decrease hydrodynamic drag, this reduction seems to be lower with depth, especially after 0.75 m depth, thus suggesting that possibly performing the underwater gliding more than 0.75 m depth could not be to the benefit of the swimmer. PMID:23487502

  8. Differences in torsional performance of single- and multiple-instrument rotary systems for glide path preparation.

    PubMed

    Arias, Ana; Singh, Rupinderpal; Peters, Ove A

    2016-05-01

    A new rotary instrument has been developed to simplify the glide path preparation in root canals before shaping procedures. The purpose of this study was to compare the peak torque and force induced by nickel-titanium PathFile multiple-instrument system and the recently developed M-Wire ProGlider single instrument during glide path preparation of mesial root canals in extracted mandibular molars. Each independent canal of eight mesial roots of mandibular molars was randomly assigned to achieve a reproducible glide path with a new set of either PathFile #1 and #2 or ProGlider after negotiation with a 10 K-file. Tests were run in a standardized fashion using a torque-testing platform. Peak torque (N cm) and force (N) were registered and analysis of variance and Tukey post-hoc tests were applied. Preliminary data for stationary torque at failure were also obtained and compared with peak torque for each instrument. PathFile #1 and #2 instruments showed statistically lower peak torque (p = 0.001) and peak force (p = 0.008) than ProGlider. Torque at failure according to ADA No. 28/ISO 36030-1 was not significantly different from peak torque during glide path preparation for ProGlider instruments while it was significantly higher for PathFile #1 and #2 (p < 0.001). Under the conditions of this study, PathFile instruments developed significant lower peak torque and force during glide path preparation compared to ProGlider, which is possibly subjected to a greater contact with the canal walls due to the increase in its flute diameter at middle and coronal levels. PMID:25701538

  9. The Effect of Depth on Drag During the Streamlined Glide: A Three-Dimensional CFD Analysis

    PubMed Central

    Novais, Maria L.; Silva, António J.; Mantha, Vishveshwar R.; Ramos, Rui J.; Rouboa, Abel I.; Vilas-Boas, J. Paulo; Luís, Sérgio R.; Marinho, Daniel A.

    2012-01-01

    The aim of this study was to analyze the effects of depth on drag during the streamlined glide in swimming using Computational Fluid Dynamics. The Computation Fluid Dynamic analysis consisted of using a three-dimensional mesh of cells that simulates the flow around the considered domain. We used the K-epsilon turbulent model implemented in the commercial code Fluent® and applied it to the flow around a three-dimensional model of an Olympic swimmer. The swimmer was modeled as if he were gliding underwater in a streamlined prone position, with hands overlapping, head between the extended arms, feet together and plantar flexed. Steady-state computational fluid dynamics analyses were performed using the Fluent® code and the drag coefficient and the drag force was calculated for velocities ranging from 1.5 to 2.5 m/s, in increments of 0.50m/s, which represents the velocity range used by club to elite level swimmers during the push-off and glide following a turn. The swimmer model middle line was placed at different water depths between 0 and 1.0 m underwater, in 0.25m increments. Hydrodynamic drag decreased with depth, although after 0.75m values remained almost constant. Water depth seems to have a positive effect on reducing hydrodynamic drag during the gliding. Although increasing depth position could contribute to decrease hydrodynamic drag, this reduction seems to be lower with depth, especially after 0.75 m depth, thus suggesting that possibly performing the underwater gliding more than 0.75 m depth could not be to the benefit of the swimmer. PMID:23487502

  10. Gliding characteristics of flexor tendon and tenosynovium in carpal tunnel syndrome: a pilot study.

    PubMed

    Ettema, Anke M; Zhao, Chunfeng; Amadio, Peter C; O'Byrne, Megan M; An, Kai-Nan

    2007-04-01

    The characteristic pathological finding in carpal tunnel syndrome (CTS) is noninflammatory fibrosis of the synovium. How this fibrosis might affect tendon function, if at all, is unknown. The subsynovial connective tissue (SSCT) lies between the flexor tendons and the visceral synovium (VS) of the ulnar tenosynovial bursa. Fibrosis of the SSCT may well affect its gliding characteristics. To investigate this possibility, the relative motion of the flexor tendon and VS was observed during finger flexion in patients undergoing carpal tunnel surgery, and for comparison in hands without CTS, in an in vitro cadaver model. We used a camera to document the gliding motion of the middle finger flexor digitorum superficialis (FDS III) tendon and SSCT in three patients with CTS during carpal tunnel release and compared this with simulated active flexion in three cadavers with no antemortem history of CTS. The data were digitized with the use of Analyze Software (Biomedical Imaging Resource, Mayo Clinic, Rochester, MN). In the CTS patients, the SSCT moved en bloc with the tendon, whereas, in the controls the SSCT moved smoothly and separately from the tendon. The ratio of VS to tendon motion was higher for the patients than in the cadaver controls. These findings suggest that in patients with CTS the synovial fibrosis has altered the gliding characteristics of the SSCT. The alterations in the gliding characteristics of the SSCT may affect the ability of the tendons in the carpal tunnel to glide independently from each other, or from the nearby median nerve. These abnormal tendon mechanics may play a role in the etiology of CTS. PMID:16944527

  11. Involvement of the Type IX Secretion System in Capnocytophaga ochracea Gliding Motility and Biofilm Formation

    PubMed Central

    Kita, Daichi; Shibata, Satoshi; Kikuchi, Yuichiro; Kokubu, Eitoyo; Nakayama, Koji; Saito, Atsushi

    2016-01-01

    Capnocytophaga ochracea is a Gram-negative, rod-shaped bacterium that demonstrates gliding motility when cultured on solid agar surfaces. C. ochracea possesses the ability to form biofilms; however, factors involved in biofilm formation by this bacterium are unclear. A type IX secretion system (T9SS) in Flavobacterium johnsoniae was shown to be involved in the transport of proteins (e.g., several adhesins) to the cell surface. Genes orthologous to those encoding T9SS proteins in F. johnsoniae have been identified in the genome of C. ochracea; therefore, the T9SS may be involved in biofilm formation by C. ochracea. Here we constructed three ortholog-deficient C. ochracea mutants lacking sprB (which encodes a gliding motility adhesin) or gldK or sprT (which encode T9SS proteins in F. johnsoniae). Gliding motility was lost in each mutant, suggesting that, in C. ochracea, the proteins encoded by sprB, gldK, and sprT are necessary for gliding motility, and SprB is transported to the cell surface by the T9SS. For the ΔgldK, ΔsprT, and ΔsprB strains, the amounts of crystal violet-associated biofilm, relative to wild-type values, were 49%, 34%, and 65%, respectively, at 48 h. Confocal laser scanning and scanning electron microscopy revealed that the biofilms formed by wild-type C. ochracea were denser and bacterial cells were closer together than in those formed by the mutant strains. Together, these results indicate that proteins exported by the T9SS are key elements of the gliding motility and biofilm formation of C. ochracea. PMID:26729712

  12. Ancient phylogenetic divergence of the enigmatic African rodent Zenkerella and the origin of anomalurid gliding.

    PubMed

    Heritage, Steven; Fernández, David; Sallam, Hesham M; Cronin, Drew T; Esara Echube, José Manuel; Seiffert, Erik R

    2016-01-01

    The "scaly-tailed squirrels" of the rodent family Anomaluridae have a long evolutionary history in Africa, and are now represented by two gliding genera (Anomalurus and Idiurus) and a rare and obscure genus (Zenkerella) that has never been observed alive by mammalogists. Zenkerella shows no anatomical adaptations for gliding, but has traditionally been grouped with the glider Idiurus on the basis of craniodental similarities, implying that either the Zenkerella lineage lost its gliding adaptations, or that Anomalurus and Idiurus evolved theirs independently. Here we present the first nuclear and mitochondrial DNA sequences of Zenkerella, based on recently recovered whole-body specimens from Bioko Island (Equatorial Guinea), which show unambiguously that Zenkerella is the sister taxon of Anomalurus and Idiurus. These data indicate that gliding likely evolved only once within Anomaluridae, and that there were no subsequent evolutionary reversals. We combine this new molecular evidence with morphological data from living and extinct anomaluromorph rodents and estimate that the lineage leading to Zenkerella has been evolving independently in Africa since the early Eocene, approximately 49 million years ago. Recently discovered fossils further attest to the antiquity of the lineage leading to Zenkerella, which can now be recognized as a classic example of a "living fossil," about which we know remarkably little. The osteological markers of gliding are estimated to have evolved along the stem lineage of the Anomalurus-Idiurus clade by the early Oligocene, potentially indicating that this adaptation evolved in response to climatic perturbations at the Eocene-Oligocene boundary (∼34 million years ago). PMID:27602286

  13. [Structure and solidity of new bone in a cortical gliding hole by implanted leg screw (author's transl)].

    PubMed

    Hutzschenreuter, P; Claes, L

    1976-07-23

    Leg screws were implanted in 30 tibia diaphysis. 112 days later in the gliding hole there was new lamellar bone round of the screw head, neck of screw and into the both first screw threads. After screw explantation we measured in 8 cases the solidity of the new bone. Under conditions of tension measurement, we use 341 N per millimeter cortical thread surfaces to put out all new bone from the gliding hole. The results of these tension measurements were cylindric fragments. The remodelling into the gliding hole seems to be the results of static stress and dynamic compensation for reaching a defect in living cortical bone. PMID:962685

  14. Aerodynamic force generation, performance and control of body orientation during gliding in sugar gliders (Petaurus breviceps).

    PubMed

    Bishop, Kristin L

    2007-08-01

    Gliding has often been discussed in the literature as a possible precursor to powered flight in vertebrates, but few studies exist on the mechanics of gliding in living animals. In this study I analyzed the 3D kinematics of sugar gliders (Petaurus breviceps) during short glides in an enclosed space. Short segments of the glide were captured on video, and the positions of marked anatomical landmarks were used to compute linear distances and angles, as well as whole body velocities and accelerations. From the whole body accelerations I estimated the aerodynamic forces generated by the animals. I computed the correlations between movements of the limbs and body rotations to examine the control of orientation during flight. Finally, I compared these results to those of my earlier study on the similarly sized and distantly related southern flying squirrel (Glaucomys volans). The sugar gliders in this study accelerated downward slightly (1.0+/-0.5 m s(-2)), and also accelerated forward (2.1+/-0.6 m s(-2)) in all but one trial, indicating that the body weight was not fully supported by aerodynamic forces and that some of the lift produced forward acceleration rather than just balancing body weight. The gliders used high angles of attack (44.15+/-3.12 degrees ), far higher than the angles at which airplane wings would stall, yet generated higher lift coefficients (1.48+/-0.18) than would be expected for a stalled wing. Movements of the limbs were strongly correlated with body rotations, suggesting that sugar gliders make extensive use of limb movements to control their orientation during gliding flight. In addition, among individuals, different limb movements were associated with a given body rotation, suggesting that individual variation exists in the control of body rotations. Under similar conditions, flying squirrels generated higher lift coefficients and lower drag coefficients than sugar gliders, yet had only marginally shallower glides. Flying squirrels have a

  15. ACS Quicklook PDF products

    NASA Astrophysics Data System (ADS)

    Suchkov, Anatoly

    1999-12-01

    This report details the features of the ACS quicklook PDF products produced by the HST data pipeline. The requirements closely follow the design of paper products recommended by the Data Quality Committee, with appropriate changes required to fully support ACS.

  16. Location of Body Wave Microseism Sources Using Three-Component Data From a Large Aperture Seismic Array in China

    NASA Astrophysics Data System (ADS)

    Liu, Q.; Koper, K. D.; Burlacu, R.; Ni, S.; Wang, F.

    2015-12-01

    From September 2013 through October 2014 up to 100 Guralp CMG-3 broadband seismometers were deployed in the WT-Array (WTA) in northwest China. The aperture of WTA is about 700 km, with an average station spacing of approximately 50 km. Here, we process continuous, three-component WTA data to detect and locate body wave microseism sources in four distinct period bands: 1.0-2.5 s, 2.5-5 s, 5-10 s, and 10-20 s. We back-project vertical component data through a 1D reference Earth model (AK135) to a global grid of hypothetical source locations, assuming P-wave (30o-90o), PP-wave (60o-180o), and S-wave (30o-75o) propagation. At the same time, we rotate the horizontals and back-project the radial and transverse components of the wavefield. For each frequency band, grid point, and assumed origin time, the array power is calculated from the amplitude of a windowed, filtered, and tapered time domain beam constructed with fourth-root stacking. We find strong P-wave and S-wave noise sources in the North Pacific and North Atlantic Oceans. Shorter period sources (2.5-5 s) are mainly observed in the North Pacific Ocean, while both short and long period (2.5-20 s) sources are observed in the North Atlantic Ocean. Median power plots for each month during September 2013 through October 2014 show distinct seasonal variations. The energy peaks in the North Atlantic are visible from November to March and strong energy is also observed in the North Pacific from October to April. We also observe PP-waves in the Southern Ocean, especially for May-August 2014. Using classical f-k analysis and plane-wave propagation, we are able to confirm the back-projection results. To improve our understanding of body wave microseism generation, we compare the observed P, S, and PP wave microseism locations with the predictions of significant wave height and wave-wave interactions derived from the WAVEWATCH III ocean model.From September 2013 through October 2014 up to 100 Guralp CMG-3 broadband

  17. 3D microfluidic chips with integrated functional microelements fabricated by a femtosecond laser for studying the gliding mechanism of cyanobacteria.

    PubMed

    Hanada, Yasutaka; Sugioka, Koji; Shihira-Ishikawa, Ikuko; Kawano, Hiroyuki; Miyawaki, Atsushi; Midorikawa, Katsumi

    2011-06-21

    Phormidium, a genus of filamentous cyanobacteria, forms endosymbiotic associations with seedling roots that accelerate the growth of the vegetable seedlings. Understanding the gliding mechanism of Phormidium will facilitate improved formation of this association and increased vegetable production. To observe the gliding movements, we fabricated various microfluidic chips termed nanoaquariums using a femtosecond (fs) laser. Direct fs laser writing, followed by annealing and successive wet etching in dilute hydrofluoric acid solution, can easily produce three-dimensional (3D) microfluidics with different structures embedded in a photostructurable glass. Using the fs laser, optical waveguides and filters were integrated with the microfluidic structures in the microchips, allowing the gliding mechanism to be more easily clarified. Using this apparatus, we found that CO(2) secreted from the seedling root attracts Phormidium in the presence of light, and determined the light intensity and specific wavelength necessary for gliding. PMID:21562650

  18. Phase field modeling of a glide dislocation transmission across a coherent sliding interface

    NASA Astrophysics Data System (ADS)

    Zheng, Songlin; Ni, Yong; He, Linghui

    2015-04-01

    Three-dimensional phase field microelasticity modeling and simulation capable of representing core structure and elastic interactions of dislocations are used to study a glide dislocation transmission across a coherent sliding interface in face-centered cubic metals. We investigate the role of the interface sliding process, which is described as the reversible motion of interface dislocation on the interfacial barrier strength to transmission. Numerical results show that a wider transient interface sliding zone develops on the interface with a lower interfacial unstable stacking fault energy to trap the glide dislocation leading to a stronger barrier to transmission. The interface sliding zone shrinks in the case of high applied stress and low mobility for the interfacial dislocation. This indicates that such interfacial barrier strength might be rate dependent. We discuss the calculated interfacial barrier strength for the Cu/Ni interface from the contribution of interface sliding comparable to previous atomistic simulations.

  19. Interlayer-glide-driven isosymmetric phase transition in compressed In2Se3

    NASA Astrophysics Data System (ADS)

    Ke, Feng; Liu, Cailong; Gao, Yang; Zhang, Junkai; Tan, Dayong; Han, Yonghao; Ma, Yanzhang; Shu, Jinfu; Yang, Wenge; Chen, Bin; Mao, Ho-Kwang; Chen, Xiao-Jia; Gao, Chunxiao

    2014-05-01

    We report an anomalous phase transition in compressed In2Se3. The high-pressure studies indicate that In2Se3 transforms to a new isosymmetric R-3m structure at 0.8 GPa whilst the volume collapses by ˜7%. This phase transition involves a pressure-induced interlayer shear glide with respect to one another. Consequently, the outer Se atoms of one sheet locate into the interstitial sites of three Se atoms in the neighboring sheets that are weakly connected by van der Waals interaction. Interestingly, this interlayer shear glide changes the stacking sequence significantly but leaves crystal symmetry unaffected. This study provides an insight to the mechanisms of the intriguing isosymmetric phase transition.

  20. An innovative way to reinsert dislodged Arndt blocker using urological glide wire

    PubMed Central

    Pillai, Rahul; Ancheri, Sneha Ann; Dharmalingam, Sathish Kumar; Sahajanandan, Raj

    2016-01-01

    The Arndt blocker is positioned in the desired bronchus using a wire loop which couples the blocker with a fiberoptic bronchoscope (FOB). The wire loop once removed cannot be reinserted in 5F and 7F blockers making repositioning of the blocker difficult. A 34-year-old female was to undergo left thoracotomy followed by laparoscopic cholecystectomy. The left lung was isolated with a 7F Arndt bronchial blocker. During one-lung ventilation, the wire loop was removed for oxygen insufflation. There was loss of lung isolation during the procedure and dislodgement of the blocker was confirmed by FOB. The initial attempts to reintroduce the blocker into the left main bronchus failed. An alternative technique using a glide wire was attempted which resulted in successful reintroduction of the Arndt blocker. The 0.032 inch zebra glide wire may be effectively used to reposition a dislodged Arndt blocker if the wire loop has been removed. PMID:27052085

  1. Feather roughness reduces flow separation during low Reynolds number glides of swifts.

    PubMed

    van Bokhorst, Evelien; de Kat, Roeland; Elsinga, Gerrit E; Lentink, David

    2015-10-01

    Swifts are aerodynamically sophisticated birds with a small arm and large hand wing that provides them with exquisite control over their glide performance. However, their hand wings have a seemingly unsophisticated surface roughness that is poised to disturb flow. This roughness of about 2% chord length is formed by the valleys and ridges of overlapping primary feathers with thick protruding rachides, which make the wing stiffer. An earlier flow study of laminar-turbulent boundary layer transition over prepared swift wings suggested that swifts can attain laminar flow at a low angle of attack. In contrast, aerodynamic design theory suggests that airfoils must be extremely smooth to attain such laminar flow. In hummingbirds, which have similarly rough wings, flow measurements on a 3D printed model suggest that the flow separates at the leading edge and becomes turbulent well above the rachis bumps in a detached shear layer. The aerodynamic function of wing roughness in small birds is, therefore, not fully understood. Here, we performed particle image velocimetry and force measurements to compare smooth versus rough 3D-printed models of the swift hand wing. The high-resolution boundary layer measurements show that the flow over rough wings is indeed laminar at a low angle of attack and a low Reynolds number, but becomes turbulent at higher values. In contrast, the boundary layer over the smooth wing forms open laminar separation bubbles that extend beyond the trailing edge. The boundary layer dynamics of the smooth surface varies non-linearly as a function of angle of attack and Reynolds number, whereas the rough surface boasts more consistent turbulent boundary layer dynamics. Comparison of the corresponding drag values, lift values and glide ratios suggests, however, that glide performance is equivalent. The increased structural performance, boundary layer robustness and equivalent aerodynamic performance of rough wings might have provided small (proto) birds with

  2. Sandbox experiments on gravitational spreading and gliding in the presence of fluid overpressures

    NASA Astrophysics Data System (ADS)

    Mourgues, R.; Cobbold, P. R.

    2006-05-01

    Whereas in previous analogue experiments on gravitational spreading and gliding, detachment occurred on a ductile layer, we have used a relatively new technique of injecting compressed air into sand packs so as to simulate the effects of fluid overpressures in sedimentary strata and to trigger slope instabilities. In our experiments, the governing equations yield scales for dimensions, stresses and fluid pressure. However, the more transitory phenomena of production and decrease of overpressure cannot be suitably scaled. By using layers of differing permeability, we are able to produce sharp detachments in models made of sand alone. The experiments involve gravity spreading or gravity gliding. In gravity spreading, propagation of the detachment and of extensional deformation depends on the fluid pressure. For medium values of fluid overpressure, normal faults are closely spaced, numerous and bound rotated blocks. They propagate progressively toward the back of the model. For the highest pressures, the deformation propagates very fast and faults bound non-rotated blocks, which slide on an efficient basal detachment. Fault dips are also controlled by fluid pressure and by frictional resistance at the base. To model gravitational gliding required an apparatus with a more complex system of air injection. We did a series of experiments using injection windows of various lengths and compared the results with predictions from a quasi-3D analytical model of sliding. In contrast with predictions for an infinite slope, sliding depends on (1) the fluid overpressure on the detachment, (2) the fluid overpressure in the body of the sliding sheet, and (3) the shape of the detachment surface. In particular, we show that frictional resistance at the lower edge is a primary control on the dynamics of gliding.

  3. GLIDE: a grid-based light-weight infrastructure for data-intensive environments

    NASA Technical Reports Server (NTRS)

    Mattmann, Chris A.; Malek, Sam; Beckman, Nels; Mikic-Rakic, Marija; Medvidovic, Nenad; Chrichton, Daniel J.

    2005-01-01

    The promise of the grid is that it will enable public access and sharing of immense amounts of computational and data resources among dynamic coalitions of individuals and institutions. However, the current grid solutions make several limiting assumptions that curtail their widespread adoption. To address these limitations, we present GLIDE, a prototype light-weight, data-intensive middleware infrastructure that enables access to the robust data and computational power of the grid on DREAM platforms.

  4. On the irradiation creep by climb-enabled glide of dislocations

    NASA Astrophysics Data System (ADS)

    Barashev, A. V.; Golubov, S. I.; Stoller, R. E.

    2016-08-01

    In the climb-enabled glide model of irradiation creep, the plastic deformation is defined by the elastic deflections of pinned dislocations, which is an inconsistency. We argue that this relation is incorrect; instead, as in other pinning-unpinning-type models, the dislocations move from one set of obstacles to another, so that the inter-obstacle spacing determines creep rate, whereas the dependence on the applied stress is only implicit in the unpinning time.

  5. Quadrupedal locomotor performance in two species of arboreal squirrels: predicting energy savings of gliding.

    PubMed

    Flaherty, Elizabeth A; Ben-David, Merav; Smith, Winston P

    2010-10-01

    Gliding allows mammals to exploit canopy habitats of old-growth forests possibly as a means to save energy. To assess costs of quadrupedal locomotion for a gliding arboreal mammal, we used open-flow respirometry and a variable-speed treadmill to measure oxygen consumption and to calculate cost of transport, excess exercise oxygen consumption, and excess post-exercise oxygen consumption for nine northern flying squirrels (Glaucomys sabrinus) and four fox squirrels (Sciurus niger). Our results indicate that oxygen consumption during exercise by flying squirrels was 1.26-1.65 times higher than predicted based on body mass, and exponentially increased with velocity (from 0.84 ± 0.03 ml O(2) kg(-1) s(-1) at 0.40 m s(-1) to 1.55 ± 0.03 ml O(2) kg(-1) s(-1) at 0.67 m s(-1)). Also, cost of transport in flying squirrels increased with velocity, although excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. In contrast, oxygen consumption during exercise for fox squirrels was similar to predicted, varying from 0.51 (±0.02) ml O(2) kg(-1) s(-1) at 0.63 m s(-1) to 0.54 (±0.03) ml O(2) kg(-1) s(-1) at 1.25 m s(-1). In addition, the cost of transport for fox squirrels decreased with velocity, while excess exercise oxygen consumption and excess post-exercise oxygen consumption did not. Collectively, these observations suggest that unlike fox squirrels, flying squirrels are poorly adapted to prolonged bouts of quadrupedal locomotion. The evolution of skeletal adaptations to climbing, leaping, and landing and the development of a gliding membrane likely has increased the cost of quadrupedal locomotion by >50% while resulting in energy savings during gliding and reduction in travel time between foraging patches. PMID:20361193

  6. Effects of cervical sustained natural apophyseal glide on forward head posture and respiratory function

    PubMed Central

    Kim, Se-Yoon; Kim, Nan-Soo; Kim, Laurentius Jongsoon

    2015-01-01

    [Purpose] To determine the effects of cervical sustained natural apophyseal glide on forward head posture and respiratory function. [Subjects and Methods] Thirty male and female adults in their 20s with forward head posture were included in the study. The subjects were divided randomly into experimental and control groups (n=15 each). Subjects in the experimental group performed cervical sustained natural apophyseal glide three times/week for four weeks while subjects in the control group did not perform the intervention. The craniovertebral angle, forced vital capacity and forced expiratory volume in the first second, as well as the % predicted value of each measurement were assessed to determine the changes in respiration functions before and after the exercise. [Results] The craniovertebral angle four weeks after the experiment was increased in the experimental group, whereas the control group showed no significant difference compared to baseline. The forced vital capacity, forced expiratory volume in the first second, and the % predicted values thereof were significantly increased in the experimental group four weeks after the experiment, but not in the control group. [Conclusion] Cervical sustained natural apophyseal glide was determined to be effective in improving neck posture and respiratory functions for patients with forward head posture. PMID:26180334

  7. A theoretical analysis of pitch stability during gliding in flying snakes.

    PubMed

    Jafari, Farid; Ross, Shane D; Vlachos, Pavlos P; Socha, John J

    2014-06-01

    Flying snakes use their entire body as a continuously morphing 'wing' to produce lift and shallow their glide trajectory. Their dominant behavior during gliding is aerial undulation, in which lateral waves are sent posteriorly down the body. This highly dynamic behavior, which is unique among animal gliders, should have substantial effects on the flight dynamics and stability of the snakes, resulting from the continuous redistribution of mass and aerodynamic forces. In this study, we develop two-dimensional theoretical models to assess the stability characteristics of snakes in the pitch direction. Previously measured force coefficients are used to simulate aerodynamic forces acting on the models, and undulation is simulated by varying mass. Model 1 is a simple three-airfoil representation of the snake's body that possesses a passively stable equilibrium solution, whose basin of stability contains initial conditions observed in experimental gliding trajectories. Model 2 is more sophisticated, with more degrees of freedom allowing for postural changes to better represent the snake's real kinematics; in addition, a restoring moment is added to simulate potential active control. The application of static and dynamic stability criteria show that Model 2 is passively unstable, but can be stabilized with a restoring moment. Overall, these models suggest that undulation does not contribute to stability in pitch, and that flying snakes require a closed-loop control system formed around a passively stable dynamical framework. PMID:24852642

  8. Wake analysis of aerodynamic components for the glide envelope of a jackdaw (Corvus monedula).

    PubMed

    KleinHeerenbrink, Marco; Warfvinge, Kajsa; Hedenström, Anders

    2016-05-15

    Gliding flight is a relatively inexpensive mode of flight used by many larger bird species, where potential energy is used to cover the cost of aerodynamic drag. Birds have great flexibility in their flight configuration, allowing them to control their flight speed and glide angle. However, relatively little is known about how this flexibility affects aerodynamic drag. We measured the wake of a jackdaw (Corvus monedula) gliding in a wind tunnel, and computed the components of aerodynamic drag from the wake. We found that induced drag was mainly affected by wingspan, but also that the use of the tail has a negative influence on span efficiency. Contrary to previous work, we found no support for the separated primaries being used in controlling the induced drag. Profile drag was of similar magnitude to that reported in other studies, and our results suggest that profile drag is affected by variation in wing shape. For a folded tail, the body drag coefficient had a value of 0.2, rising to above 0.4 with the tail fully spread, which we conclude is due to tail profile drag. PMID:26994178

  9. Prosodic effects on glide-vowel sequences in three Romance languages

    NASA Astrophysics Data System (ADS)

    Chitoran, Ioana

    2001-05-01

    Glide-vowel sequences occur in many Romance languages. In some they can vary in production, ranging from diphthongal pronunciation [ja,je] to hiatus [ia,ie]. According to native speakers' impressionistic perceptions, Spanish and Romanian both exhibit this variation, but to different degrees. Spanish favors glide-vowel sequences, while Romanian favors hiatus, occasionally resulting in different pronunciations of the same items: Spanish (b[j]ela, ind[j]ana), Romanian (b[i]ela, ind[i]ana). The third language, French, has glide-vowel sequences consistently (b[j]elle). This study tests the effect of position in the word on the acoustic duration of the sequences. Shorter duration indicates diphthong production [jV], while longer duration, hiatus [iV]. Eleven speakers (4 Spanish, 4 Romanian, 3 French), were recorded. Spanish and Romanian showed a word position effect. Word-initial sequences were significantly longer than word-medial ones (p<0.001), consistent with native speakers more frequent description of hiatus word-initially than medially. The effect was not found in French (p>0.05). In the Spanish and Romanian sentences, V in the sequence bears pitch accent, but not in French. It is therefore possible that duration is sensitive not to the presence/absence of the word boundary, but to its position relative to pitch accent. The results suggest that the word position effect is crucially enhanced by pitch accent on V.

  10. Methods to Improve Success With the GlideScope Video Laryngoscope.

    PubMed

    Nemec, Darrell; Austin, Paul N; Silvestro, Loraine S

    2015-12-01

    Occasionally intubation of patients is difficult using a video laryngoscope (GlideScope, Verathon Medical) because of an inability to guide the endotracheal tube to the glottis or pass the tube into the trachea despite an adequate view of the glottis. We examined methods to improve success when this difficulty occurs. A literature search revealed 253 potential sources, with 25 meeting search criteria: 7 randomized controlled trials, 4 descriptive studies, 8 case series, and 6 case reports. Findings from the randomized controlled trials suggested that using a flexible-tipped endotracheal tube with a rigid stylet (GlideRite, Verathon Medical) improved intubation success, whereas other methods did not, such as using a forceps-guided endotracheal tube exchanger. If a malleable stylet was used, a 90 degrees bend above the endotracheal tube cuff was preferable to a 60 degrees bend. Evidence from lower-level sources suggested that several interventions were helpful, including using a controllable stylet, a fiberoptic bronchoscope in conjunction with the GlideScope, or an intubation guide, and twisting the endotracheal tube to facilitate passage into the trachea. Providers must consider the risks and benefits of any technique, particularly if the device manufacturer does not recommend the technique. Further rigorous investigations should be conducted examining methods to increase success. PMID:26742332

  11. The driving force for glide of a threading dislocation in a strained epitaxial layer on a substrate

    NASA Astrophysics Data System (ADS)

    Freund, L. B.

    T HE PROCESS of epitaxial growth of a very thin layer onto a substrate crystal is considered for the particular situation in which the layer and substrate materials have the same crystal structure and orientation but different lattice parameters. Under these conditions, the layer grows with an intrinsic elastic strain determined by the mismatch in lattice parameters. The associated stress in the crystalline layer provides a driving force for the nucleation and motion of defects, primarily dislocations. The focus here is on the glide of a dislocation extending from the free surface of the layer to the layer-substrate interface, the so-called threading dislocation. A general definition of driving force for glide of a threading dislocation is introduced on the basis of work arguments. The definition is then applied to calculate the driving force for steady motion of an isolated threading dislocation in a strained layer, and the result includes Matthews' critical thickness concept as one of its features. Next, a kinetic equation for glide of a dislocation in semiconductor materials is proposed to estimate the glide rate of a threading dislocation in these low mobility materials. Finally, for the case of cubic materials, the general definition of driving force is applied to estimate the additional driving force on a threading dislocation due to an encounter with a dislocation on an intersecting glide plane. The results indicate that this effect is significant in blocking the glide of a threading dislocation for large mismatch strains and for layer thicknesses near the critical thickness.

  12. Postoperative Sore Throat After Laryngoscopy With Macintosh or Glide Scope Video Laryngoscope Blade in Normal Airway Patients

    PubMed Central

    Najafi, Atabak; Imani, Farsad; Makarem, Jalil; Khajavi, Mohammad Reza; Etezadi, Farhad; Habibi, Shirin; Shariat Moharari, Reza

    2014-01-01

    Background: The Glide Scope videolaryngoscope provides a suitable view for intubation, with less force required. Objectives: The present study was conducted, to compare postoperative sore throat and hoarseness after laryngoscopy and intubation, by Macintosh blade or Glide Scope video laryngoscope in normal airway patients. Patients and Methods: Three hundred patients were randomly allocated into two groups of 150: Macintosh blade laryngoscope or Glide Scope video laryngoscope. The patients were evaluated for 48 hours for sore throat and hoarseness by an interview. Results: The incidence and severity of sore throat in the Glide Scope group, at 6, 24 and 48 hours after the operation, were significantly lower than in the Macintosh laryngoscope group. In addition, the incidence of hoarseness in the Glide Scope group, at 6 and 24 hours after the operation, were significantly lower than in the Macintosh laryngoscope group. The incidence and severity of sore throat in men, at 6 and 24 hours after the operation, were significantly lower than in the women. Conclusions: The incidence and severity of sore throat and hoarseness after tracheal intubation by Glide Scope were lower than in the Macintosh laryngoscope. The incidence and severity of sore throat were increased by intubation and longer operation times. PMID:24660157

  13. Perception of visual apparent motion is modulated by a gap within concurrent auditory glides, even when it is illusory

    PubMed Central

    Wang, Qingcui; Guo, Lu; Bao, Ming; Chen, Lihan

    2015-01-01

    Auditory and visual events often happen concurrently, and how they group together can have a strong effect on what is perceived. We investigated whether/how intra- or cross-modal temporal grouping influenced the perceptual decision of otherwise ambiguous visual apparent motion. To achieve this, we juxtaposed auditory gap transfer illusion with visual Ternus display. The Ternus display involves a multi-element stimulus that can induce either of two different percepts of apparent motion: ‘element motion’ (EM) or ‘group motion’ (GM). In “EM,” the endmost disk is seen as moving back and forth while the middle disk at the central position remains stationary; while in “GM,” both disks appear to move laterally as a whole. The gap transfer illusion refers to the illusory subjective transfer of a short gap (around 100 ms) from the long glide to the short continuous glide when the two glides intercede at the temporal middle point. In our experiments, observers were required to make a perceptual discrimination of Ternus motion in the presence of concurrent auditory glides (with or without a gap inside). Results showed that a gap within a short glide imposed a remarkable effect on separating visual events, and led to a dominant perception of GM as well. The auditory configuration with gap transfer illusion triggered the same auditory capture effect. Further investigations showed that visual interval which coincided with the gap interval (50–230 ms) in the long glide was perceived to be shorter than that within both the short glide and the ‘gap-transfer’ auditory configurations in the same physical intervals (gaps). The results indicated that auditory temporal perceptual grouping takes priority over the cross-modal interaction in determining the final readout of the visual perception, and the mechanism of selective attention on auditory events also plays a role. PMID:26042055

  14. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites.

    PubMed

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Supová, Monika; Zaloudková, Margit; Balík, Karel; Lisá, Věra; Slouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0-N25 or M0-M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%-15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%-15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

  15. Support for the initial attachment, growth and differentiation of MG-63 cells: a comparison between nano-size hydroxyapatite and micro-size hydroxyapatite in composites

    PubMed Central

    Filová, Elena; Suchý, Tomáš; Sucharda, Zbyněk; Šupová, Monika; Žaloudková, Margit; Balík, Karel; Lisá, Věra; Šlouf, Miroslav; Bačáková, Lucie

    2014-01-01

    Hydroxyapatite (HA) is considered to be a bioactive material that favorably influences the adhesion, growth, and osteogenic differentiation of osteoblasts. To optimize the cell response on the hydroxyapatite composite, it is desirable to assess the optimum concentration and also the optimum particle size. The aim of our study was to prepare composite materials made of polydimethylsiloxane, polyamide, and nano-sized (N) or micro-sized (M) HA, with an HA content of 0%, 2%, 5%, 10%, 15%, 20%, 25% (v/v) (referred to as N0–N25 or M0–M25), and to evaluate them in vitro in cultures with human osteoblast-like MG-63 cells. For clinical applications, fast osseointegration of the implant into the bone is essential. We observed the greatest initial cell adhesion on composites M10 and N5. Nano-sized HA supported cell growth, especially during the first 3 days of culture. On composites with micro-size HA (2%–15%), MG-63 cells reached the highest densities on day 7. Samples M20 and M25, however, were toxic for MG-63 cells, although these composites supported the production of osteocalcin in these cells. On N2, a higher concentration of osteopontin was found in MG-63 cells. For biomedical applications, the concentration range of 5%–15% (v/v) nano-size or micro-size HA seems to be optimum. PMID:25125978

  16. Contact- and Protein Transfer-Dependent Stimulation of Assembly of the Gliding Motility Machinery in Myxococcus xanthus

    PubMed Central

    Jakobczak, Beata; Keilberg, Daniela; Wuichet, Kristin; Søgaard-Andersen, Lotte

    2015-01-01

    Bacteria engage in contact-dependent activities to coordinate cellular activities that aid their survival. Cells of Myxococcus xanthus move over surfaces by means of type IV pili and gliding motility. Upon direct contact, cells physically exchange outer membrane (OM) lipoproteins, and this transfer can rescue motility in mutants lacking lipoproteins required for motility. The mechanism of gliding motility and its stimulation by transferred OM lipoproteins remain poorly characterized. We investigated the function of CglC, GltB, GltA and GltC, all of which are required for gliding. We demonstrate that CglC is an OM lipoprotein, GltB and GltA are integral OM β-barrel proteins, and GltC is a soluble periplasmic protein. GltB and GltA are mutually stabilizing, and both are required to stabilize GltC, whereas CglC accumulate independently of GltB, GltA and GltC. Consistently, purified GltB, GltA and GltC proteins interact in all pair-wise combinations. Using active fluorescently-tagged fusion proteins, we demonstrate that GltB, GltA and GltC are integral components of the gliding motility complex. Incorporation of GltB and GltA into this complex depends on CglC and GltC as well as on the cytoplasmic AglZ protein and the inner membrane protein AglQ, both of which are components of the gliding motility complex. Conversely, incorporation of AglZ and AglQ into the gliding motility complex depends on CglC, GltB, GltA and GltC. Remarkably, physical transfer of the OM lipoprotein CglC to a ΔcglC recipient stimulates assembly of the gliding motility complex in the recipient likely by facilitating the OM integration of GltB and GltA. These data provide evidence that the gliding motility complex in M. xanthus includes OM proteins and suggest that this complex extends from the cytoplasm across the cell envelope to the OM. These data add assembly of gliding motility complexes in M. xanthus to the growing list of contact-dependent activities in bacteria. PMID:26132848

  17. Characteristics of short period secondary microseisms (SPSM) in Taiwan: The influence of shallow ocean strait on SPSM

    NASA Astrophysics Data System (ADS)

    Chen, Ying-Nien; Gung, Yuancheng; You, Shuei-Huei; Hung, Shu-Huei; Chiao, Ling-Yun; Huang, Tzu-Ying; Chen, Yen-Ling; Liang, Wen-Tzong; Jan, Sen

    2011-02-01

    Taking advantage of a unique opportunity provided by a dense array of coastal short-period seismic stations and the diverse bathymetry around Taiwan, we examine how the long-range coherent ambient noises are influenced by surrounding ocean settings using the cross-correlation functions (CCFs) between pairs of stations. The effective energy of the CCFs derived from three components of short-period seismometer data falls within the frequency range of the short period secondary microseism (SPSM). The spatial variations mapped from the amplitude asymmetry of CCFs and source migration images evidently demonstrate that the SPSM strengths are closely linked to the drastic changes in offshore ocean characteristics and result in much stronger SPSM in the shallow and narrow Taiwan Strait than in deep open seas of eastern Taiwan. The temporal variations of the CCF strengths exhibit very good correlations with the wind speeds and wave heights, explicitly indicating the observed SPSM is dominated by local sources generated from wind-driven ocean waves around offshore Taiwan.

  18. Bacterial gliding fluid dynamics on a layer of non-Newtonian slime: Perturbation and numerical study.

    PubMed

    Ali, N; Asghar, Z; Anwar Bég, O; Sajid, M

    2016-05-21

    Gliding bacteria are an assorted group of rod-shaped prokaryotes that adhere to and glide on certain layers of ooze slime attached to a substratum. Due to the absence of organelles of motility, such as flagella, the gliding motion is caused by the waves moving down the outer surface of these rod-shaped cells. In the present study we employ an undulating surface model to investigate the motility of bacteria on a layer of non-Newtonian slime. The rheological behavior of the slime is characterized by an appropriate constitutive equation, namely the Carreau model. Employing the balances of mass and momentum conservation, the hydrodynamic undulating surface model is transformed into a fourth-order nonlinear differential equation in terms of a stream function under the long wavelength assumption. A perturbation approach is adopted to obtain closed form expressions for stream function, pressure rise per wavelength, forces generated by the organism and power required for propulsion. A numerical technique based on an implicit finite difference scheme is also employed to investigate various features of the model for large values of the rheological parameters of the slime. Verification of the numerical solutions is achieved with a variational finite element method (FEM). The computations demonstrate that the speed of the glider decreases as the rheology of the slime changes from shear-thinning (pseudo-plastic) to shear-thickening (dilatant). Moreover, the viscoelastic nature of the slime tends to increase the swimming speed for the shear-thinning case. The fluid flow in the pumping (generated where the organism is not free to move but instead generates a net fluid flow beneath it) is also investigated in detail. The study is relevant to marine anti-bacterial fouling and medical hygiene biophysics. PMID:26903204

  19. Nanoscale Visualization of a Fibrillar Array in the Cell Wall of Filamentous Cyanobacteria and Its Implications for Gliding Motility▿

    PubMed Central

    Read, Nicholas; Connell, Simon; Adams, David G.

    2007-01-01

    Many filamentous cyanobacteria are motile by gliding, which requires attachment to a surface. There are two main theories to explain the mechanism of gliding. According to the first, the filament is pushed forward by small waves that pass along the cell surface. In the second, gliding is powered by the extrusion of slime through pores surrounding each cell septum. We have previously shown that the cell walls of several motile cyanobacteria possess an array of parallel fibrils between the peptidoglycan and the outer membrane and have speculated that the function of this array may be to generate surface waves to power gliding. Here, we report on a study of the cell surface topography of two morphologically different filamentous cyanobacteria, using field emission gun scanning electron microscopy (FEGSEM) and atomic force microscopy (AFM). FEGSEM and AFM images of Oscillatoria sp. strain A2 confirmed the presence of an array of fibrils, visible as parallel corrugations on the cell surface. These corrugations were also visualized by AFM scanning of fully hydrated filaments under liquid; this has not been achieved before for filamentous bacteria. FEGSEM images of Nostoc punctiforme revealed a highly convoluted, not parallel, fibrillar array. We conclude that an array of parallel fibrils, beneath the outer membrane of Oscillatoria, may function in the generation of thrust in gliding motility. The array of convoluted fibrils in N. punctiforme may have an alternative function, perhaps connected with the increase in outer membrane surface area resulting from the presence of the fibrils. PMID:17693519

  20. Effect of curing time and concentration for a chemical treatment that improves surface gliding for extrasynovial tendon grafts in vitro

    PubMed Central

    Tanaka, Toshikazu; Sun, Yu-Long; Zhao, Chunfeng; Zobitz, Mark E.; An, Kai-Nan; Amadio, Peter C.

    2013-01-01

    The purpose of this study was to evaluate whether treatment time and concentration of these reagents have an effect on the resulting gliding resistance. Forty peroneus longus (PL) tendons were used, from 20 adult mongrel dogs, along with the A2 pulley obtained from the ipsilateral hind paw. After the baseline gliding resistance was measured, the PL tendons were treated with one of three concentrations of hyaluronic acid (HA) and 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) or N-hydroxysuccinimide (NHS) mixed with 10% gelatin for various times (5, 30, and 60 min). Tendon friction was measured over 1000 cycles of simulated flexion/extension motion. Gliding resistance of the untreated PL tendons had no significant difference among the groups. After surface treatment with low concentration of HA and EDC/NHS for 5-min cure, the gliding resistance was similar to that of the untreated PL tendon and significantly higher than its 30- and 60-min treatment. For the rest of high concentration of HA and EDC/NHS groups, the gliding resistance was lower than that of untreated PL tendon. However, there was no significant difference among the timing points. It is possible to optimize the effect of surface treatment on friction and durability by regulating cure time and concentration of reagents in a canine extrasynovial tendon in vitro. PMID:16752399

  1. Rapid diffusion of magic-size islands by combined glide and vacancy mechanisms

    SciTech Connect

    Perez, D; Voter, A F; Uche, O U; Hamilton, J C

    2009-01-01

    Using molecular dynamics, nudged elastic band, and embedded atom methods, we show that certain 2D Ag islands undergo extremely rapid one-dimensional diffusion on Cu(001) surfaces. Indeed, below 300K, hopping rates for 'magic-size' islands are orders of magnitude faster than hopping rates for single Ag adatoms. This rapid diffusion requires both the c(10 x 2) hexagonally-packed superstructure typical of Ag on Cu(001) and appropriate 'magic-sizes' for the islands. The novel highly-cooperative diffusion mechanism presented here couples vacancy diffusion with simultaneous core glide.

  2. Decomposition of CCl4 and CHCl3 on gliding are plasma.

    PubMed

    Indarto, Antonius; Choi, Jae-Wook; Lee, Hwaung; Song, Hyung-Keun

    2006-01-01

    Decomposition of chlorinated hydrocarbons, CCl4 and CHCl3, in gliding plasma was examined. The effects of initial concentrations, total gas flow rates, and power consumption have been investigated. The conversion result was relatively high. It reached 80% for CCl4 and 97% for CHCl3. Using atmospheric air as the carrier gas, the plasma reaction occurred at exothermic reaction and the main products were CO2, CO, and Cl2. Transformation into CCl4 was also detected for CHCl3 decomposition reaction. The conversion of CCl4 and CHCl3 were increased with the increasing applied frequency and decreasing total gas flow rate. PMID:20050553

  3. Research on motion model for the hypersonic boost-glide aircraft

    NASA Astrophysics Data System (ADS)

    Xu, Shenda; Wu, Jing; Wang, Xueying

    2015-11-01

    A motion model for the hypersonic boost-glide aircraft(HBG) was proposed in this paper, which also analyzed the precision of model through simulation. Firstly the trajectory of HBG was analyzed, and a scheme which divide the trajectory into two parts then build the motion model on each part. Secondly a restrained model of boosting stage and a restrained model of J2 perturbation were established, and set up the observe model. Finally the analysis of simulation results show the feasible and high-accuracy of the model, and raise a expectation for intensive research.

  4. A 3D model of a reverse vortex flow gliding arc reactor

    NASA Astrophysics Data System (ADS)

    Trenchev, G.; Kolev, St.; Bogaerts, A.

    2016-06-01

    In this computational study, a gliding arc plasma reactor with a reverse-vortex flow stabilization is modelled for the first time by a fluid plasma description. The plasma reactor operates with argon gas at atmospheric pressure. The gas flow is simulated using the k-ε Reynolds-averaged Navier–Stokes turbulent model. A quasi-neutral fluid plasma model is used for computing the plasma properties. The plasma arc movement in the reactor is observed, and the results for the gas flow, electrical characteristics, plasma density, electron temperature, and gas temperature are analyzed.

  5. Emergent spinless Weyl semimetals between the topological crystalline insulator and normal insulator phases with glide symmetry

    NASA Astrophysics Data System (ADS)

    Kim, Heejae; Murakami, Shuichi

    2016-05-01

    We construct a theory describing phase transitions between the spinless topological crystalline insulator phase with glide symmetry and a normal insulator phase. We show that a spinless Weyl semimetal phase should intervene between these two phases. Here, because all the bands are free from degeneracy in general, a gap closing between a single conduction band and a single valence band at phase transition generally gives rise to a pair creation of Weyl nodes; hence the Weyl semimetal phase naturally appears. We show the relationship between the change of the Z2 topological number when the system goes through the Weyl semimetal phase, and the trajectory of the Weyl nodes.

  6. Use-Dependent Curvature Changes in the GlideRite® Reusable Intubation Stylet.

    PubMed

    Smith, Cameron R; Urdaneta, Felipe; Gravenstein, Nikolaus

    2016-05-15

    The Glidescope® is one of the most widely used video laryngoscopes in the market. It is often used with a purpose-built, reusable, "nonmalleable" stainless steel stylet, the GlideRite®. In this study, we investigated whether this stylet retains its original curvature with repeated use and sterilization. To evaluate the shape and curvature of the stylets, high-resolution digital photographs were made of 55 GlideRite stylets (5 new and 50 randomly selected from operating room stock) laid on a grid background and analyzed using Adobe Photoshop®. In a similar fashion, 1 new stylet was inserted into and removed 100 times from an endotracheal tube and photographed every 20 cycles to determine the impact of use on stylet shape. For the 5 new stylets, the handle-to-tip angle was very consistent (23.44° ± 1.04°). The stylets in clinical use varied widely in their configuration. For analysis, they were divided into 3 groups based on the handle-to-tip angle: ±1 SD of the new stylets, those with a shallower angle (straighter), and those with a steeper angle (more curved). The handle-to-tip angles were as follows: 23.07° ± 0.80° (±1 SD), 18.39° ± 2.59° (straighter), and 27.65° ± 2.73° (more curved). Analysis of variance showed that the new and ±1 SD groups were not significantly different, but both the straighter (P = 0.0002) and more curved (P = 0.0048) groups were significantly different from new. The repeated insertion and removal of a new stylet resulted in gradual straightening of the curve of the stylet from 22° at baseline to 19.2° after 100 insertion/removal cycles. Used GlideRite reusable stylets are not reliably equivalent to new ones in terms of their shape or curvature. Given that the repeated insertion and removal of a new stylet from an endotracheal tube resulted in their straightening, it is likely that clinical use has the same effect. Because many used stylets were actually more curved than the new ones, we hypothesize that practitioners

  7. Characterization of atmospheric pressure H2O/O2 gliding arc plasma for the production of OH and O radicals

    NASA Astrophysics Data System (ADS)

    Roy, N. C.; Hafez, M. G.; Talukder, M. R.

    2016-08-01

    Atmospheric pressure H 2 O / O 2 gliding arc plasma is generated by a 88 Hz , 6 kV AC power supply. The properties of the produced plasma are investigated by optical emission spectroscopy. The relative intensity, rotational, vibrational, excitation temperatures and electron density are studied as a function of applied voltage, electrode spacing, and oxygen flow rate. The rotational and vibrational temperatures are determined simulating the OH ( A 2 Σ + ( v ″ = 0 ) → X 2 Π ( v ' = 0 ) ) bands with the aid of LIFBASE simulation software. The excitation temperature is obtained from the CuI transition taking non-thermal equilibrium condition into account employing intensity ratio method. The electron density is approximated from the H α Stark broadening using the Voigt profile fitting method. It is observed that the rotational and vibrational temperatures decrease with increasing electrode spacing and O 2 flow rate, but increase with the applied voltage. The excitation temperature is found to increase with increasing applied voltage and O 2 flow rate, but decrease with electrode spacing. The electron density increases with increasing applied voltage while it seems to be in a downward trend with increasing electrode spacing and O 2 flow rate.

  8. The mysterious nature of bacterial surface (gliding) motility: A focal adhesion-based mechanism in Myxococcus xanthus.

    PubMed

    Islam, Salim T; Mignot, Tâm

    2015-10-01

    Motility of bacterial cells promotes a range of important physiological phenomena such as nutrient detection, harm avoidance, biofilm formation, and pathogenesis. While much research has been devoted to the mechanism of bacterial swimming in liquid via rotation of flagellar filaments, the mechanisms of bacterial translocation across solid surfaces are poorly understood, particularly when cells lack external appendages such as rotary flagella and/or retractile type IV pili. Under such limitations, diverse bacteria at the single-cell level are still able to "glide" across solid surfaces, exhibiting smooth translocation of the cell along its long axis. Though multiple gliding mechanisms have evolved in different bacterial classes, most remain poorly characterized. One exception is the gliding motility mechanism used by the Gram-negative social predatory bacterium Myxococcus xanthus. The available body of research suggests that M. xanthus gliding motility is mediated by trafficked multi-protein (Glt) cell envelope complexes, powered by proton-driven flagellar stator homologues (Agl). Through coupling to the substratum via polysaccharide slime, Agl-Glt assemblies can become fixed relative to the substratum, forming a focal adhesion site. Continued directional transport of slime-associated substratum-fixed Agl-Glt complexes would result in smooth forward movement of the cell. In this review, we have provided a comprehensive synthesis of the latest mechanistic and structural data for focal adhesion-mediated gliding motility in M. xanthus, with emphasis on the role of each Agl and Glt protein. Finally, we have also highlighted the possible connection between the motility complex and a new type of spore coat assembly system, suggesting that gliding and cell envelope synthetic complexes are evolutionarily linked. PMID:26520023

  9. Glass micro-wire tracks for guiding kinesin-powered gliding motion of microtubules

    NASA Astrophysics Data System (ADS)

    Kim, K.; Liao, A. L.; Sikora, A.; Oliveira, D.; Umetsu, M.; Kumagai, I.; Adschiri, T.; Hwang, W.; Teizer, W.

    2013-03-01

    Kinesin, an enzyme molecule found in eukaryotic cells, walks on specific paths, namely microtubules. These microtubules, self-assembled in-vitro, cooperate with kinesin molecules by playing the role of either a track for the molecular motors or a lengthy cargo lorry driven by the motor molecules. One of major challenges in utilization of the latter case, which is particularly advantageous for practical applications because of the longer cruising range and the higher carrying capacity of the bio-transporter, is herding the gliding microtubules. A general approach to achieve this goal is aligning motor molecules along a track. In previous attempts such tracks were physically and/or chemically patterned on a glass surface. We use a kinesin-coated glass wire to demonstrate kinesin-powered gliding movement of microtubules confined by the wire-like structure. This new approach distinguishes itself in that the glass wire track is an independent entity, being separable from a two-dimensional surface in principle. We will also discuss quantitative analysis of the guided motility and potential applications.

  10. A protein secretion system linked to bacteroidete gliding motility and pathogenesis

    PubMed Central

    Sato, Keiko; Naito, Mariko; Yukitake, Hideharu; Hirakawa, Hideki; Shoji, Mikio; McBride, Mark J.; Rhodes, Ryan G.; Nakayama, Koji

    2009-01-01

    Porphyromonas gingivalis secretes strong proteases called gingipains that are implicated in periodontal pathogenesis. Protein secretion systems common to other Gram-negative bacteria are lacking in P. gingivalis, but several proteins, including PorT, have been linked to gingipain secretion. Comparative genome analysis and genetic experiments revealed 11 additional proteins involved in gingipain secretion. Six of these (PorK, PorL, PorM, PorN, PorW, and Sov) were similar in sequence to Flavobacterium johnsoniae gliding motility proteins, and two others (PorX and PorY) were putative two-component system regulatory proteins. Real-time RT-PCR analysis revealed that porK, porL, porM, porN, porP, porT, and sov were down-regulated in P. gingivalis porX and porY mutants. Disruption of the F. johnsoniae porT ortholog resulted in defects in motility, chitinase secretion, and translocation of a gliding motility protein, SprB adhesin, to the cell surface, providing a link between a unique protein translocation system and a motility apparatus in members of the Bacteroidetes phylum. PMID:19966289

  11. Two Essential Light Chains Regulate the MyoA Lever Arm To Promote Toxoplasma Gliding Motility

    PubMed Central

    Williams, Melanie J.; Alonso, Hernan; Enciso, Marta; Egarter, Saskia; Sheiner, Lilach; Meissner, Markus; Striepen, Boris; Smith, Brian J.

    2015-01-01

    ABSTRACT Key to the virulence of apicomplexan parasites is their ability to move through tissue and to invade and egress from host cells. Apicomplexan motility requires the activity of the glideosome, a multicomponent molecular motor composed of a type XIV myosin, MyoA. Here we identify a novel glideosome component, essential light chain 2 (ELC2), and functionally characterize the two essential light chains (ELC1 and ELC2) of MyoA in Toxoplasma. We show that these proteins are functionally redundant but are important for invasion, egress, and motility. Molecular simulations of the MyoA lever arm identify a role for Ca2+ in promoting intermolecular contacts between the ELCs and the adjacent MLC1 light chain to stabilize this domain. Using point mutations predicted to ablate either the interaction with Ca2+ or the interface between the two light chains, we demonstrate their contribution to the quality, displacement, and speed of gliding Toxoplasma parasites. Our work therefore delineates the importance of the MyoA lever arm and highlights a mechanism by which this domain could be stabilized in order to promote invasion, egress, and gliding motility in apicomplexan parasites. PMID:26374117

  12. Effect of cellular filamentation on adventurous and social gliding motility of Myxococcus xanthus

    PubMed Central

    Sun, Hong; Yang, Zhaomin; Shi, Wenyuan

    1999-01-01

    Filamentous bacterial cells often provide biological information that is not readily evident in normal-size cells. In this study, the effect of cellular filamentation on gliding motility of Myxococcus xanthus, a Gram-negative social bacterium, was investigated. Elongation of the cell body had different effects on adventurous and social motility of M. xanthus. The rate of A-motility was insensitive to cell-body elongation whereas the rate of S-motility was reduced dramatically as the cell body got longer, indicating that these two motility systems work in different ways. The study also showed that filamentous wild-type cells glide smoothly with relatively straight, long cell bodies. However, filamentous cells of certain social motility mutants showed zigzag, tangled cell bodies on a solid surface, apparently a result of a lack of coordination between different fragments within the filaments. Further genetic and biochemical analyses indicated that the uncoordinated movements of these mutant filaments were correlated with the absence of cell surface fibril materials, indicating a possible new function for fibrils. PMID:10611358

  13. Heart rate and estimated energy expenditure of flapping and gliding in black-browed albatrosses.

    PubMed

    Sakamoto, Kentaro Q; Takahashi, Akinori; Iwata, Takashi; Yamamoto, Takashi; Yamamoto, Maki; Trathan, Philip N

    2013-08-15

    Albatrosses are known to expend only a small amount of energy during flight. The low energy cost of albatross flight has been attributed to energy-efficient gliding (soaring) with sporadic flapping, although little is known about how much time and energy albatrosses expend in flapping versus gliding during cruising flight. Here, we examined the heart rates (used as an instantaneous index of energy expenditure) and flapping activities of free-ranging black-browed albatrosses (Thalassarche melanophrys) to estimate the energy cost of flapping as well as time spent in flapping activities. The heart rate of albatrosses during flight (144 beats min(-1)) was similar to that while sitting on the water (150 beats min(-1)). In contrast, heart rate was much higher during takeoff and landing (ca. 200 beats min(-1)). Heart rate during cruising flight was linearly correlated with the number of wing flaps per minute, suggesting an extra energy burden of flapping. Albatrosses spend only 4.6±1.4% of their time flapping during cruising flight, which was significantly lower than during and shortly after takeoff (9.8±3.5%). Flapping activity, which amounted to just 4.6% of the time in flight, accounted for 13.3% of the total energy expenditure during cruising flight. These results support the idea that albatrosses achieve energy-efficient flight by reducing the time spent in flapping activity, which is associated with high energy expenditure. PMID:23661772

  14. CO2 Dissociation by Low Current Gliding Discharge in the Reverse Vortex Flow

    NASA Astrophysics Data System (ADS)

    Gutsol, Alexander

    2012-10-01

    If performed with high energy efficiency, plasma-chemical dissociation of carbon dioxide can be a way of converting and storing energy when there is an excess of electric energy, for example generated by solar elements of wind turbines. CO2 dissociation with efficiency of up to 90% was reported earlier for low pressure microwave discharge in supersonic flow. A new plasma-chemical system uses a low current gliding discharge in the reverse vortex flow of plasma gas. The system is a development of the Gliding Arc in Tornado reactor. The system was used to study dissociation of CO2 in wide ranges of the following experimental parameters: reactor pressure (15-150 kPa), discharge current (50-500 mA), gas flow rate (3-30 liters per minute), and electrode gap length (1-10 cm). Additionally, the effect of thermal energy recuperation on CO2 dissociation efficiency was tested. Plasma chemical efficiency of CO2 dissociation is very low (about 3%) in a short discharge at low pressures (about 15 kPa) when it is defined by electronic excitation. The highest efficiency (above 40%) was reached at pressures 50-70 kPa in a long discharge with thermal energy recuperation. It means that the process is controlled by thermal dissociation with subsequent effective quenching. Plasma chemical efficiency was determined from the data of chromatographic analysis and oscilloscope electric power integration, and also was checked calorimetrically by the thermal balance of the system.

  15. The novel marine gliding zooflagellate genus Mantamonas (Mantamonadida ord. n.: Apusozoa).

    PubMed

    Glücksman, Edvard; Snell, Elizabeth A; Berney, Cédric; Chao, Ema E; Bass, David; Cavalier-Smith, Thomas

    2011-04-01

    Mantamonasis a novel genus of marine gliding zooflagellates probably related to apusomonad and planomonad Apusozoa. Using phase and differential interference contrast microscopy we describe the type species Mantamonas plasticasp. n. from coastal sediment in Cumbria, England. Cells are ∼5μm long, ∼5μm wide, asymmetric, flattened, biciliate, and somewhat plastic. The posterior cilium, on which they glide smoothly over the substratum, is long and highly acronematic. The much thinner, shorter, and almost immobile anterior cilium points forward to the cell's left. These morphological and behavioural traits suggest thatMantamonasis a member of the protozoan phylum Apusozoa. Analyses of 18S and 28S rRNA gene sequences of Mantamonas plasticaand a second genetically very different marine species from coastal sediment in Tanzania show Mantamonasas a robustly monophyletic clade, that is very divergent from all other eukaryotes. 18S rRNA trees mostly placeMantamonaswithin unikonts (opisthokonts, Apusozoa, and Amoebozoa) but its precise position varies with phylogenetic algorithm and/or taxon and nucleotide position sampling; it may group equally weakly as sister to Planomonadida, Apusomonadida or Breviata. On 28S rRNA and joint 18/28S rRNA phylogenies (including 11 other newly obtained apusozoan/amoebozoan 28S rRNA sequences) it consistently strongly groups with Apusomonadida (Apusozoa). PMID:20884290

  16. Development of a gliding arc plasma reactor for CO₂destruction.

    PubMed

    Kim, Seong Cheon; Chun, Young Nam

    2014-01-01

    A gliding arc plasma reactor was designed to destruct carbon dioxide (CO₂), which is a major greenhouse gas. To increase the CO₂destruction rate with a high processing gas volume, an orifice baffle for gathering the gas flow at the centre of the electrodes was installed in the gliding arc plasma reactor. The CO₂inflows with methane (CH₄) and steam (H₂O) improve the CO₂destruction. The parametric studies have been made of the change of CH4 addition, gas injection velocity of the centre nozzle, change of CO₂gas flow rate, and orifice baffle configuration. The produced gases were measured, and the data analysis has been achieved in determining the CO₂destruction rate, CH₄conversion rate, destruction energy efficiency, and selectivity for CO₂and H₂. The highest CO₂ destruction rate for each parameter has been shown as follows: the CH₄/CO₂ratio is 1 as 40%, and the injection gas velocity is 69.5 m/s as 35.7%, the CO₂flow rate is 5 L/min as 42.6%, and the orifice baffle is Type 1, which had the smallest internal area, as 35.7%. PMID:25189841

  17. Atomistic study on the generation and gliding properties of pyramidal dislocations in magnesium

    NASA Astrophysics Data System (ADS)

    Kaburaki, Hideo; Itakura, Mitsuhiro; Yamaguchi, Masatake

    Plastic deformation of magnesium and its alloys is attracting great interest as one of the candidate materials for energy-conserving lightweight structural metals. The generation of non-basal pyramidal dislocations near the c-axis direction is the key to enhancing plasticity in these highly anisotropic hcp magnesium materials. However, the fundamental understanding of the generation and gliding properties of pyramidal dislocations is still not clear because of the large Burgers vector. Using the molecular dynamics method, we have successfully generated < c + a > type I and II screw dislocations from the crack set in the perfect magnesium crystal by applying the shear stress. Visualization of these dislocations is important because the core structures are complex and largely extended. Comparing the results by first-principles calculations, we have found that the core of the type I screw dislocation is smoothly extended while that of the type II screw dislocation has a corrugated structure. We also found that both dislocations can easily cross-slip to other slip planes. In particular, it is observed that the core of the gliding pyramidal type I screw dislocation cross-slips to other slip planes. The detailed processes of cross-slip are elucidated in the presentation.

  18. A protein secretion system linked to bacteroidete gliding motility and pathogenesis.

    PubMed

    Sato, Keiko; Naito, Mariko; Yukitake, Hideharu; Hirakawa, Hideki; Shoji, Mikio; McBride, Mark J; Rhodes, Ryan G; Nakayama, Koji

    2010-01-01

    Porphyromonas gingivalis secretes strong proteases called gingipains that are implicated in periodontal pathogenesis. Protein secretion systems common to other Gram-negative bacteria are lacking in P. gingivalis, but several proteins, including PorT, have been linked to gingipain secretion. Comparative genome analysis and genetic experiments revealed 11 additional proteins involved in gingipain secretion. Six of these (PorK, PorL, PorM, PorN, PorW, and Sov) were similar in sequence to Flavobacterium johnsoniae gliding motility proteins, and two others (PorX and PorY) were putative two-component system regulatory proteins. Real-time RT-PCR analysis revealed that porK, porL, porM, porN, porP, porT, and sov were down-regulated in P. gingivalis porX and porY mutants. Disruption of the F. johnsoniae porT ortholog resulted in defects in motility, chitinase secretion, and translocation of a gliding motility protein, SprB adhesin, to the cell surface, providing a link between a unique protein translocation system and a motility apparatus in members of the Bacteroidetes phylum. PMID:19966289

  19. The Effects of One-Dimensional Glide On the Reaction Kinetics of Interstitial Clusters

    SciTech Connect

    Heinisch, Howard L.; Singh, B. N.; Golubov, S. I.

    2000-09-01

    Collision cascades in metals produce small interstitial clusters and perfect dislocation loops that glide in thermally activated, one-dimensional (1D) random walks. These gliding defects can change their Burgers vectors by thermal activation or by interactions with other defects. Their migration is therefore ?mixed 1D/3D migration? along a 3D path consisting of 1D segments. The defect reaction kinetics under mixed 1D/3D diffusion are different from both pure 1D diffusion and pure 3D diffusion, both of which can be formulated within analytical rate theory models of microstructure evolution under irradiation. Atomic-scale Kinetic Monte Carlo defect migration simulations are used to investigate the effects of mixed 1D/3D migration on defect reaction kinetics as a guide for implementing mixed 1D/3D migration into the theory. The dependence of sink strength on the size and concentration of sinks under mixed 1D/3D migration lies between those for pure 1D and pure 3D migration and varies with the average distance between direction changes, L. The sink strength for sinks of size R under mixed 1D/3D migration can be approximated by an expression that varies directly as R2 for values of L greater than the sink size. The transition from mixed 1D/3D to pure 3D diffusion as L decreases is demonstrated in the simulations.

  20. Pitch glide effect induced by a nonlinear string-barrier interaction

    NASA Astrophysics Data System (ADS)

    Kartofelev, Dmitri; Stulov, Anatoli; Välimäki, Vesa

    2015-10-01

    Interactions of a vibrating string with its supports and other spatially distributed barriers play a significant role in the physics of many stringed musical instruments. It is well known that the tone of the string vibrations is determined by the string supports, and that the boundary conditions of the string termination may cause a short-lasting initial fundamental frequency shifting. Generally, this phenomenon is associated with the nonlinear modulation of the stiff string tension. The aim of this paper is to study the initial frequency glide phenomenon that is induced only by the string-barrier interaction, apart from other possible physical causes, and without the interfering effects of dissipation and dispersion. From a numerical simulation perspective, this highly nonlinear problem may present various difficulties, not the least of which is the risk of numerical instability. We propose a numerically stable and a purely kinematic model of the string-barrier interaction, which is based on the travelling wave solution of the ideal string vibration. The model is capable of reproducing the motion of the vibrating string exhibiting the initial fundamental frequency glide, which is caused solely by the complex nonlinear interaction of the string with its termination. The results presented in this paper can expand our knowledge and understanding of the timbre evolution and the physical principles of sound generation of numerous stringed instruments, such as lutes called the tambura, sitar and biwa.

  1. Energy Management of Manned Boost-Glide Vehicles: A Historical Perspective

    NASA Technical Reports Server (NTRS)

    Day, Richard E.

    2004-01-01

    As flight progressed from propellers to jets to rockets, the propulsive energy grew exponentially. With the development of rocket-only boosted vehicles, energy management of these boost-gliders became a distinct requirement for the unpowered return to base, alternate landing site, or water-parachute landing, starting with the X-series rocket aircraft and terminating with the present-day Shuttle. The problem presented here consists of: speed (kinetic energy) - altitude (potential energy) - steep glide angles created by low lift-to-drag ratios (L/D) - distance to landing site - and the bothersome effects of the atmospheric characteristics varying with altitude. The primary discussion regards post-boost, stabilized glides; however, the effects of centrifugal and geopotential acceleration are discussed as well. The aircraft and spacecraft discussed here are the X-1, X-2, X-15, and the Shuttle; and to a lesser, comparative extent, Mercury, Gemini, Apollo, and lifting bodies. The footprints, landfalls, and methods developed for energy management are also described. The essential tools required for energy management - simulator planning, instrumentation, radar, telemetry, extended land or water range, Mission Control Center (with specialist controllers), and emergency alternate landing sites - were first established through development of early concepts and were then validated by research flight tests.

  2. Velocity Fluctuations in Kinesin-1 Gliding Motility Assays Originate in Motor Attachment Geometry Variations.

    PubMed

    Palacci, Henri; Idan, Ofer; Armstrong, Megan J; Agarwal, Ashutosh; Nitta, Takahiro; Hess, Henry

    2016-08-01

    Motor proteins such as myosin and kinesin play a major role in cellular cargo transport, muscle contraction, cell division, and engineered nanodevices. Quantifying the collective behavior of coupled motors is critical to our understanding of these systems. An excellent model system is the gliding motility assay, where hundreds of surface-adhered motors propel one cytoskeletal filament such as an actin filament or a microtubule. The filament motion can be observed using fluorescence microscopy, revealing fluctuations in gliding velocity. These velocity fluctuations have been previously quantified by a motional diffusion coefficient, which Sekimoto and Tawada explained as arising from the addition and removal of motors from the linear array of motors propelling the filament as it advances, assuming that different motors are not equally efficient in their force generation. A computational model of kinesin head diffusion and binding to the microtubule allowed us to quantify the heterogeneity of motor efficiency arising from the combination of anharmonic tail stiffness and varying attachment geometries assuming random motor locations on the surface and an absence of coordination between motors. Knowledge of the heterogeneity allows the calculation of the proportionality constant between the motional diffusion coefficient and the motor density. The calculated value (0.3) is within a standard error of our measurements of the motional diffusion coefficient on surfaces with varying motor densities calibrated by landing rate experiments. This allowed us to quantify the loss in efficiency of coupled molecular motors arising from heterogeneity in the attachment geometry. PMID:27414063

  3. Concerted Action of Two Formins in Gliding Motility and Host Cell Invasion by Toxoplasma gondii

    PubMed Central

    Daher, Wassim; Plattner, Fabienne; Carlier, Marie-France; Soldati-Favre, Dominique

    2010-01-01

    The invasive forms of apicomplexan parasites share a conserved form of gliding motility that powers parasite migration across biological barriers, host cell invasion and egress from infected cells. Previous studies have established that the duration and direction of gliding motility are determined by actin polymerization; however, regulators of actin dynamics in apicomplexans remain poorly characterized. In the absence of a complete ARP2/3 complex, the formin homology 2 domain containing proteins and the accessory protein profilin are presumed to orchestrate actin polymerization during host cell invasion. Here, we have undertaken the biochemical and functional characterization of two Toxoplasma gondii formins and established that they act in concert as actin nucleators during invasion. The importance of TgFRM1 for parasite motility has been assessed by conditional gene disruption. The contribution of each formin individually and jointly was revealed by an approach based upon the expression of dominant mutants with modified FH2 domains impaired in actin binding but still able to dimerize with their respective endogenous formin. These mutated FH2 domains were fused to the ligand-controlled destabilization domain (DD-FKBP) to achieve conditional expression. This strategy proved unique in identifying the non-redundant and critical roles of both formins in invasion. These findings provide new insights into how controlled actin polymerization drives the directional movement required for productive penetration of parasites into host cells. PMID:20949068

  4. Latest Sea-Operations in the Macaronesian region with Unmanned Autonomous Marine Gliding Vehicles

    NASA Astrophysics Data System (ADS)

    Barrera, Carlos; Lorenzo, Alvaro; Viera, Josue; Morales, Tania; Vega, Daura; Rueda, Maria Jose; Llinas, Octavio

    2013-04-01

    Current advances on key marine technology fields provide nowadays a broad range of autonomous unmanned platforms addressed for an efficient and cost-effective ocean observation, with a suitable level of success in terms of endurance, reliability and useful gathered information. In this context, a multidisciplinary family of unmanned autonomous vehicles addressed to monitor both coastal and open-ocean areas plays a relevant role. During the last month, some of the newest unmanned gliding vehicle technologies have been tested within the context of the Oceanic Platform of the Canary Islands (PLOCAN) in varied operational scenarios aiming different technical and scientific purposes, all of them joined in direct partnership with the company provider and other R&D institutions in some cases. Among others, representative examples in this way are the missions under the name Challenger One, Vulcano and SB02 through surface and underwater gliding vehicles, performed mostly in the surrounding subtropical waters of the ESTOC site observatory in the Canary Islands archipelago. The main gathered operational and scientific results from these missions are presented in this work as a sign of new ocean observing technologies within the framework of the Macaronesian Marine and Maritime Observation Strategy (R3M) and linked with the current European rules programs and projects in this field. Keywords: autonomous vehicle, gliders, R3M, ocean observatory, monitoring, marine robotics, ESTOC,

  5. Examining spring wet slab and glide avalanche occurrence along the Going-to-the-Sun Road corridor, Glacier National Park, Montana, USA

    USGS Publications Warehouse

    Peitzsch, Erich H.; Jordy Hendrikx; Fagre, Daniel B.; Blase Reardon

    2012-01-01

    The results suggest that the role of air temperature and snowpack settlement appear to be the most important variables in wet slab and glide avalanche occurrence. When applied to the 2011 season, the results of the CART model are encouraging and they enhance our understanding of some of the required meteorological and snowpack conditions for wet slab and glide avalanche occurrence.

  6. Microfabricated AC impedance sensor

    DOEpatents

    Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

    2002-01-01

    A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

  7. A bond graph model for the sample extraction/injection system of a microsized gas chromatographic instrument

    NASA Astrophysics Data System (ADS)

    Lin, Jie; Wang, Wanjun; Murphy, Michael C.; Overton, Edward

    1996-09-01

    A bond graph model of the sample extraction/injection system of a prototype portable gas chromatographic instrument has been developed. In addition to performing the same functions as current portable gas chromatographs (GCs), the new generation of GC instruments is designed to perform extraction of analytes from liquid and solid samples. The prototype instrument achieves these improvements by taking of advantage of microfabrication technologies and microprocessor control in the design. A novel sample extraction/injection module is essential to the improved performance of the portable instrument, which will include microfabricated components such as inlets, interface chips, fluid channels, control valves, optimal heater/sensor combinations, and multiport connectors. In order to achieve the desired analytical performance, all of the major components are heated to 250 °C during different stages of a sample analysis. Predicting the performance of the system in this operating regime requires the modeling and analysis of system behavior in two interacting energy domains, fluid and thermal. This article represents the first effort to understand the dynamic behavior of the thermofluid aspect of micro-GC instruments and one of the first attempts to apply the widely-used bond graph technique to modeling and analysis of microsized thermofluid systems. Simulation results using the bond graph model closely match available experimental data, with differences typically less than 10%. This demonstrates that fluid dynamic theory for macroscale systems, and the bond graph method based on it, can be readily applied to microscale systems with these dimensions. The bond graph method can be a useful computer-aided design tool for the development of a new generation of truly integrated micro-GC instruments and sensors fabricated with micromachining technology.

  8. AC magnetohydrodynamic microfluidic switch

    SciTech Connect

    Lemoff, A V; Lee, A P

    2000-03-02

    A microfluidic switch has been demonstrated using an AC Magnetohydrodynamic (MHD) pumping mechanism in which the Lorentz force is used to pump an electrolytic solution. By integrating two AC MHD pumps into different arms of a Y-shaped fluidic circuit, flow can be switched between the two arms. This type of switch can be used to produce complex fluidic routing, which may have multiple applications in {micro}TAS.

  9. ACS Symposium Support

    SciTech Connect

    Kenneth D. Jordan

    2010-02-20

    The funds from this DOE grant were used to help cover the travel costs of five students and postdoctoral fellows who attended a symposium on 'Hydration: From Clusters to Aqueous Solutions' held at the Fall 2007 American Chemical Society Meeting in Boston, MA, August 19-23. The Symposium was sponsored by the Physical Chemistry Division, ACS. The technical program for the meeting is available at http://phys-acs.org/fall2007.html.

  10. Gliding Box method applied to trace element distribution of a geochemical data set

    NASA Astrophysics Data System (ADS)

    Paz González, Antonio; Vidal Vázquez, Eva; Rosario García Moreno, M.; Paz Ferreiro, Jorge; Saa Requejo, Antonio; María Tarquis, Ana

    2010-05-01

    The application of fractal theory to process geochemical prospecting data can provide useful information for evaluating mineralization potential. A geochemical survey was carried out in the west area of Coruña province (NW Spain). Major elements and trace elements were determined by standard analytical techniques. It is well known that there are specific elements or arrays of elements, which are associated with specific types of mineralization. Arsenic has been used to evaluate the metallogenetic importance of the studied zone. Moreover, as can be considered as a pathfinder of Au, as these two elements are genetically associated. The main objective of this study was to use multifractal analysis to characterize the distribution of three trace elements, namely Au, As, and Sb. Concerning the local geology, the study area comprises predominantly acid rocks, mainly alkaline and calcalkaline granites, gneiss and migmatites. The most significant structural feature of this zone is the presence of a mylonitic band, with an approximate NE-SW orientation. The data set used in this study comprises 323 samples collected, with standard geochemical criteria, preferentially in the B horizon of the soil. Occasionally where this horizon was not present, samples were collected from the C horizon. Samples were taken in a rectilinear grid. The sampling lines were perpendicular to the NE-SW tectonic structures. Frequency distributions of the studied elements departed from normal. Coefficients of variation ranked as follows: Sb < As < Au. Significant correlation coefficients between Au, Sb, and As were found, even if these were low. The so-called ‘gliding box' algorithm (GB) proposed originally for lacunarity analysis has been extended to multifractal modelling and provides an alternative to the ‘box-counting' method for implementing multifractal analysis. The partitioning method applied in GB algorithm constructs samples by gliding a box of certain size (a) over the grid map in all