Species status assessment report New Mexico meadow jumping mouse (Zapus hudsonius luteus)
US Fish and Wildlife Service, Department of the Interior — The New Mexico meadow jumping mouse (Zapus hudsonius luteus) (jumping mouse) lives in dense riparian herbaceous vegetation along streams from southern Colorado to...
Recovery Outline: New Mexico Jumping Mouse (Zapus hudsonius luteus)
US Fish and Wildlife Service, Department of the Interior — The purpose of this recovery outline is to provide an interim strategy to guide the conservation and recovery of the New Mexico meadow jumping mouse (jumping mouse)...
Directory of Open Access Journals (Sweden)
Jennifer K. Frey
2015-08-01
Full Text Available Hibernation is a key life history feature that can impact many other crucial aspects of a species’ biology, such as its survival and reproduction. I examined the timing of hibernation and reproduction in the federally endangered New Mexico meadow jumping mouse (Zapus hudsonius luteus, which occurs across a broad range of latitudes and elevations in the American Southwest. Data from museum specimens and field studies supported predictions for later emergence and shorter active intervals in montane populations relative to lower elevation valley populations. A low-elevation population located at Bosque del Apache National Wildlife Refuge (BANWR in the Rio Grande valley was most similar to other subspecies of Z. hudsonius: the first emergence date was in mid-May and there was an active interval of 162 days. In montane populations of Z. h. luteus, the date of first emergence was delayed until mid-June and the active interval was reduced to ca 124–135 days, similar to some populations of the western jumping mouse (Z. princeps. Last date of immergence into hibernation occurred at about the same time in all populations (mid to late October. In montane populations pregnant females are known from July to late August and evidence suggests that they have a single litter per year. At BANWR two peaks in reproduction were expected based on similarity of active season to Z. h. preblei. However, only one peak was clearly evident, possibly due to later first reproduction and possible torpor during late summer. At BANWR pregnant females are known from June and July. Due to the short activity season and geographic variation in phenology of key life history events of Z. h. luteus, recommendations are made for the appropriate timing for surveys for this endangered species.
Frey, Jennifer K
2015-01-01
Hibernation is a key life history feature that can impact many other crucial aspects of a species' biology, such as its survival and reproduction. I examined the timing of hibernation and reproduction in the federally endangered New Mexico meadow jumping mouse (Zapus hudsonius luteus), which occurs across a broad range of latitudes and elevations in the American Southwest. Data from museum specimens and field studies supported predictions for later emergence and shorter active intervals in montane populations relative to lower elevation valley populations. A low-elevation population located at Bosque del Apache National Wildlife Refuge (BANWR) in the Rio Grande valley was most similar to other subspecies of Z. hudsonius: the first emergence date was in mid-May and there was an active interval of 162 days. In montane populations of Z. h. luteus, the date of first emergence was delayed until mid-June and the active interval was reduced to ca 124-135 days, similar to some populations of the western jumping mouse (Z. princeps). Last date of immergence into hibernation occurred at about the same time in all populations (mid to late October). In montane populations pregnant females are known from July to late August and evidence suggests that they have a single litter per year. At BANWR two peaks in reproduction were expected based on similarity of active season to Z. h. preblei. However, only one peak was clearly evident, possibly due to later first reproduction and possible torpor during late summer. At BANWR pregnant females are known from June and July. Due to the short activity season and geographic variation in phenology of key life history events of Z. h. luteus, recommendations are made for the appropriate timing for surveys for this endangered species.
Woodman, Neal; Carleton, Michael D.
2012-01-01
Constantine S. Rafinesque described Sorex dichrurus as a shrew in 1833, based on a specimen he found in a proprietary museum near Niagara Falls on the New York/Ontario border. The name subsequently has been ignored by the scientific community. By describing this specimen as a shrew and ascribing it to the genus Sorex, Rafinesque clearly indicated that his species should be considered a member of the taxonomic family now recognized as the Soricidae (Mammalia, Eulipotyphla). Yet, the description of the animal, and its comparison to ‘‘Gerbillus,’’ clearly identify it as a dipodid rodent, specifically Zapus hudsonius (Zimmermann, 1780); S. dichrurus should be treated as a junior subjective synonym of that taxon. Based on its type locality of Goat Island, New York, this name is also a junior synonym of the subspecies Z. hudsonius canadensis (Davies, 1798).
CTG trinucleotide repeat "big jumps": large expansions, small mice.
Directory of Open Access Journals (Sweden)
Mário Gomes-Pereira
2007-04-01
Full Text Available Trinucleotide repeat expansions are the genetic cause of numerous human diseases, including fragile X mental retardation, Huntington disease, and myotonic dystrophy type 1. Disease severity and age of onset are critically linked to expansion size. Previous mouse models of repeat instability have not recreated large intergenerational expansions ("big jumps", observed when the repeat is transmitted from one generation to the next, and have never attained the very large tract lengths possible in humans. Here, we describe dramatic intergenerational CTG*CAG repeat expansions of several hundred repeats in a transgenic mouse model of myotonic dystrophy type 1, resulting in increasingly severe phenotypic and molecular abnormalities. Homozygous mice carrying over 700 trinucleotide repeats on both alleles display severely reduced body size and splicing abnormalities, notably in the central nervous system. Our findings demonstrate that large intergenerational trinucleotide repeat expansions can be recreated in mice, and endorse the use of transgenic mouse models to refine our understanding of triplet repeat expansion and the resulting pathogenesis.
The effects of Piperine on the jumping induced by Naloxone in Morphine dependent mice
Directory of Open Access Journals (Sweden)
Moghadam Nia AA
2001-07-01
Full Text Available Black pepper has been used in traditional medicine as an analgesic. In this investigation, the effects of piperine, an alkaloid derived from black pepper seeds on the jumping induced by naloxone were studied on morphine dependent mice. This experimental study was conducted on case (piperine and control (saline groups of mice. Mice were made dependent to morphine using Marshall method. For evaluation of dependency, the number of jumps after naloxone injection was counted in a period of 30 minutes. There was a significant difference between number of jumps of mice in saline (10 ml/kg, IP and drug groups (piperine 25, 50, 75 mg/kg, IP, as well as significant differences in latency period for jumping behavior in two groups. Based on these results, piperine may affect the intensity of morphine dependency.
DEFF Research Database (Denmark)
Sannino, Francesco
2013-01-01
We propose an alternative paradigm to the conjectured Miransky scaling potentially underlying the physics describing the transition from the conformally broken to the conformally restored phase when tuning certain parameters such as the number of flavors in gauge theories. According to the new...... paradigm the physical scale and henceforth also the massive spectrum of the theory jump at the lower boundary of the conformal window. In particular we propose that a theory can suddenly jump from a Quantum Chromodynamics type spectrum, at the lower boundary of the conformal window, to a conformal one...... without particle interpretation. The jumping scenario, therefore, does not support a near-conformal dynamics of walking type. We will also discuss the impact of jumping dynamics on the construction of models of dynamical electroweak symmetry breaking....
Dorobantu, V
2012-01-01
When the laws of Physics are taken seriously, the sports can benefit in getting better results, as was the case of the high jump in Flop style, so that the athlete sprints diagonally towards the bar,then curve and leap backwards over it. The jumper, in this case, has the center of mass under the bar, fact which allows improvement of the performance.
Risk, Jumps, and Diversification
DEFF Research Database (Denmark)
Bollerslev, Tim; Law, Tzuo Hann; Tauchen, George
We test for price discontinuities, or jumps, in a panel of high-frequency intraday returns for forty large-cap stocks and an equiweighted index from these same stocks. Jumps are naturally classified into two types: common and idiosyncratic. Common jumps affect all stocks, albeit to varying degree...
Visser, Albert
2014-01-01
In this paper we study a new relation between sentences: the jump relation. The idea of the jump relation is based on an analysis of Feferman's Theorem that the inconsistency of a theory U is interpretable over U. The jump relation is based on a converse of Feferman's Theorem: if a sentence is inter
Steerable Miniature Jumping Robot
Kovac, Mirko; Schlegel, Manuel; Zufferey, Jean-Christophe; Floreano, Dario
2010-01-01
Jumping is used in nature by many small animals to locomote in cluttered environments or in rough terrain. It offers small systems the benefit of overcoming relatively large obstacles at a low energetic cost. In order to be able to perform repetitive jumps in a given direction, it is important to be able to upright after landing, steer and jump again. In this article, we review and evaluate the uprighting and steering principles of existing jumping robots and present a novel spherical robot w...
Rebilas, Krzysztof
2013-01-01
Consider a skier who goes down a takeoff ramp, attains a speed "V", and jumps, attempting to land as far as possible down the hill below (Fig. 1). At the moment of takeoff the angle between the skier's velocity and the horizontal is [alpha]. What is the optimal angle [alpha] that makes the jump the longest possible for the fixed magnitude of the…
Nye, Susan B.
2010-01-01
Jumping rope is an activity that can be fun and enjoyable for all students. It requires minimal activity space, can be performed individually or in small groups, and is an inexpensive way to engage students in a lifelong physical activity. Jumping rope is commonly used by coaches and athletes for training purposes to improve aerobic endurance,…
Nye, Susan B.
2010-01-01
Jumping rope is an activity that can be fun and enjoyable for all students. It requires minimal activity space, can be performed individually or in small groups, and is an inexpensive way to engage students in a lifelong physical activity. Jumping rope is commonly used by coaches and athletes for training purposes to improve aerobic endurance,…
DEFF Research Database (Denmark)
Bollerslev, Tim; Todorov, Victor
We propose a new and flexible non-parametric framework for estimating the jump tails of Itô semimartingale processes. The approach is based on a relatively simple-to-implement set of estimating equations associated with the compensator for the jump measure, or its "intensity", that only utilizes ...
Lavička, H; Kiss, T; Lutz, E; Jex, I
2011-01-01
We analyze a special class of 1-D quantum walks (QWs) realized using optical multi-ports. We assume non-perfect multi-ports showing errors in the connectivity, i.e. with a small probability the multi- ports can connect not to their nearest neighbor but to another multi-port at a fixed distance - we call this a jump. We study two cases of QW with jumps where multiple displacements can emerge at one timestep. The first case assumes time-correlated jumps (static disorder). In the second case, we choose the positions of jumps randomly in time (dynamic disorder). The probability distributions of position of the QW walker in both instances differ significantly: dynamic disorder leads to a Gaussian-like distribution, while for static disorder we find two distinct behaviors depending on the parity of jump size. In the case of even-sized jumps, the distribution exhibits a three-peak profile around the position of the initial excitation, whereas the probability distribution in the odd case follows a Laplace-like discre...
Kim, Ho-Young
2016-11-01
Water striders can jump on water as high as they can jump on land. Quick jumps allow them to avoid sudden dangers such as predators' attacks, and therefore understanding how they make such a dramatic motion for survival can shed light on the ultimate level of semi-aquatic motility achievable through evolution. However, the mechanism of their vertical jumping from a water surface has eluded hydrodynamic explanations so far. By observing movements of water strider legs and theoretically analyzing their dynamic interactions with deforming liquid-air interface, we have recently found that different species of jumping striders always tune their leg rotation speed with a force just below that required to break the water surface to reach the maximum take-off velocity. Here, we start with discussing the fundamental theories of dynamics of floating and sinking of small objects. The theories then enable us to analyze forces acting on a water strider while it presses down the water surface to fully exploit the capillary force. We further introduce a 68-milligram at-scale robotic insect capable of jumping on water without splash, strikingly similar to the real strider, by utilizing the water surface just as a trampoline.
Abderrahmane, Hamid; Kasimov, Aslan
2013-11-01
We report an experimental observation of a new symmetry breaking of circular hydraulic jump into a self-organized structure that consists of a spinning polygonal jump and logarithmic-spiral waves of fluid elevation downstream. The waves are strikingly similar to spiral density waves in galaxies. The fluid flow exhibits counterparts of salient morphological features of galactic flows, in particular the outflow from the center, jets, circum-nuclear rings, gas inflows toward the galactic center, and vortices. The hydrodynamic instability revealed here may have a counterpart that plays a role in the formation and sustainability of spiral arms in galaxies.
Directory of Open Access Journals (Sweden)
Oscar Castro-Orgaz
2015-04-01
Full Text Available The transition from subcritical to supercritical flow when the inflow Froude number Fo is close to unity appears in the form of steady state waves called undular hydraulic jump. The characterization of the undular hydraulic jump is complex due to the existence of a non-hydrostatic pressure distribution that invalidates the gradually-varied flow theory, and supercritical shock waves. The objective of this work is to present a mathematical model for the undular hydraulic jump obtained from an approximate integration of the Reynolds equations for turbulent flow assuming that the Reynolds number R is high. Simple analytical solutions are presented to reveal the physics of the theory, and a numerical model is used to integrate the complete equations. The limit of application of the theory is discussed using a wave breaking condition for the inception of a surface roller. The validity of the mathematical predictions is critically assessed using physical data, thereby revealing aspects on which more research is needed
Garcia, Sebastian
2010-01-01
Eastward ridge jumps bring the volcanic zones of Iceland back to the centre of the hotspot in response to the absolute westward drift of the Mid-Atlantic Ridge. Mantellic pulses triggers these ridge jumps. One of them is occurring in Southern Iceland, whereas the exact conditions of the last ridge jump in Northern Iceland remain controversial. The diachronous evolution of these two parts of Iceland may be related to the asymmetric plume-ridge interaction when comparing Northern and Southern I...
Directory of Open Access Journals (Sweden)
Struzik Artur
2016-04-01
Full Text Available Study aim: The elastic potential energy accumulated in the musculotendinous units during the countermovement phase of a jump adds up to the energy supplied by the contracting muscles used in the take-off phase. Consequently, the total mechanical energy used during the jump may reach higher values. Stiffness represents a quantitative measure of a body’s elastic properties. Therefore, the aim of this study was to establish the relationship between leg stiffness and the countermovement jump height.
Exploring Lightning Jump Characteristics
Chronis, Themis; Carey, Larry D.; Schultz, Christopher J.; Schultz, Elise; Calhoun, Kristin; Goodman, Steven J.
2014-01-01
This study is concerned with the characteristics of storms exhibiting an abrupt temporal increase in the total lightning flash rate (i.e., lightning jump, LJ). An automated storm tracking method is used to identify storm "clusters" and total lightning activity from three different lightning detection systems over Oklahoma, northern Alabama and Washington, D.C. On average and for different employed thresholds, the clusters that encompass at least one LJ (LJ1) last longer, relate to higher Maximum Expected Size of Hail, Vertical Integrated Liquid and lightning flash rates (area-normalized) than the clusters that did not exhibit any LJ (LJ0). The respective mean values for LJ1 (LJ0) clusters are 80 min (35 min), 14 mm (8 mm), 25 kg per square meter (18 kg per square meter) and 0.05 flash per min per square kilometer (0.01 flash per min per square kilometer). Furthermore, the LJ1 clusters are also characterized by slower decaying autocorrelation functions, a result that implies a less "random" behavior in the temporal flash rate evolution. In addition, the temporal occurrence of the last LJ provides an estimate of the time remaining to the storm's dissipation. Depending of the LJ strength (i.e., varying thresholds), these values typically range between 20-60 min, with stronger jumps indicating more time until storm decay. This study's results support the hypothesis that the LJ is a proxy for the storm's kinematic and microphysical state rather than a coincidental value.
Attari, Babak; Weislogel, Mark; Wollman, Andrew; Chen, Yongkang; Snyder, Trevor
2016-11-01
Large droplets and puddles jump spontaneously from sufficiently hydrophobic surfaces during routine drop tower tests. The simple low-cost passive mechanism can in turn be used as an experimental device to investigate dynamic droplet phenomena for drops up to 10,000 times larger than their normal terrestrial counterparts. We provide or confirm quick and qualitative design guides for such 'drop shooters' as employed in drop tower tests including relationships to predict droplet ejection durations and velocities as functions of drop volume, surface texture, surface contour, wettability pattern, drop volume, and fluid properties including contact angle. The latter are determined via profile image comparisons with numerical equilibrium interface computations. Water drop volumes of 0.04 to 400 mL at ejection speeds of -0.007 to 0.12 m/s are demonstrated. An example application of the puddle jump method is made to the classic problem of regime mapping for low-gravity phase change heat transfer for large impinging drops. Many other candidate problems might be identified.
DEFF Research Database (Denmark)
Bonn, D.; Andersen, Anders Peter; Bohr, Tomas
2009-01-01
We present a study of hydraulic jumps with flow predominantly in one direction, created either by confining the flow to a narrow channel with parallel walls or by providing an inflow in the form of a narrow sheet. In the channel flow, we find a linear height profile upstream of the jump as expected...
Electrostatic charging of jumping droplets
Miljkovic, Nenad; Preston, Daniel J.; Enright, Ryan; Wang, Evelyn N.
2013-09-01
With the broad interest in and development of superhydrophobic surfaces for self-cleaning, condensation heat transfer enhancement and anti-icing applications, more detailed insights on droplet interactions on these surfaces have emerged. Specifically, when two droplets coalesce, they can spontaneously jump away from a superhydrophobic surface due to the release of excess surface energy. Here we show that jumping droplets gain a net positive charge that causes them to repel each other mid-flight. We used electric fields to quantify the charge on the droplets and identified the mechanism for the charge accumulation, which is associated with the formation of the electric double layer at the droplet-surface interface. The observation of droplet charge accumulation provides insight into jumping droplet physics as well as processes involving charged liquid droplets. Furthermore, this work is a starting point for more advanced approaches for enhancing jumping droplet surface performance by using external electric fields to control droplet jumping.
Jump conditions in transonic equilibria
Energy Technology Data Exchange (ETDEWEB)
Guazzotto, L.; Betti, R. [Department of Mechanical Engineering, University of Rochester, Rochester, New York 14627 (United States); Jardin, S. C. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08540 (United States)
2013-04-15
In the present paper, the numerical calculation of transonic equilibria, first introduced with the FLOW code in Guazzotto et al.[Phys. Plasmas 11, 604 (2004)], is critically reviewed. In particular, the necessity and effect of imposing explicit jump conditions at the transonic discontinuity are investigated. It is found that 'standard' (low-{beta}, large aspect ratio) transonic equilibria satisfy the correct jump condition with very good approximation even if the jump condition is not explicitly imposed. On the other hand, it is also found that high-{beta}, low aspect ratio equilibria require the correct jump condition to be explicitly imposed. Various numerical approaches are described to modify FLOW to include the jump condition. It is proved that the new methods converge to the correct solution even in extreme cases of very large {beta}, while they agree with the results obtained with the old implementation of FLOW in lower-{beta} equilibria.
DEFF Research Database (Denmark)
Ravn, Susanne; Voigt, M; Simonsen, Erik Bruun
1999-01-01
Six male subjects, three professional ballet dancers and three elite volleyball players, performed maximal vertical jumps from 1) a static preparatory position (squat jump), 2) starting with a countermovement (countermovement jump) and 3) a specific jump for ballet and for volleyball, respectively....... The jumps were recorded on highspeed film (500 Hz) combined with registration of ground reaction forces, and net joint moments were calculated by inverse dynamics. The purpose was to investigate the choice of strategy in two standard jumps, squat jump and countermovement jump. The volleyball jump...... was performed with a sequential strategy and the ballet jump was performed with a simultaneous strategy. In the two standard jumps, the choice of strategy was individual and not related to training background. This was additionally confirmed in a test of seven ballet dancers and seven volleyball players....
Frequency Jump Detection and Analysis
2008-12-01
CUMULATIVE SUM JUMP DETECTION The Cumulative Sum ( CUSUM ) is a classic change-point analysis technique that uses the cumulative sum of the...sum and y is the average of the data. The CUSUM slope indicates the value of the data with respect to the overall average. A flat cumulative sum...sudden change in the CUSUM slope indicates a jump in the data. The CUSUM plot for a data set having a single jump will have a V or inverted V shape
Realized Jump Risk and Equity Return in China
Guojin Chen; Xiaoqun Liu; Peilin Hsieh; Xiangqin Zhao
2014-01-01
We utilize the realized jump components to explore a new jump (including nonsystematic jump and systematic jump) risk factor model. After estimating daily realized jumps from high-frequency transaction data of the Chinese A-share stocks, we calculate monthly jump size, monthly jump standard deviation, and monthly jump arrival rate and then use those monthly jump factors to explain the return of the following month. Our empirical results show that the jump tail risk can explain the equity retu...
Rook Jumping Maze Design Considerations
Neller, Todd W.; Fisher, Adrian; Choga, Munyaradzi T.; Lalvani, Samir M.; McCarty, Kyle D.
We define the Rook Jumping Maze, provide historical perspective, and describe a generation method for such mazes. When applying stochastic local search algorithms to maze design, most creative effort concerns the definition of an objective function that rates maze quality. We define and discuss several maze features to consider in such a function definition. Finally, we share our preferred design choices, make design process observations, and note the applicability of these techniques to variations of the Rook Jumping Maze.
The Effect of Depth Jumps and Weight Training on Leg Strength and Vertical Jump.
Clutch, David; And Others
1983-01-01
Two experiments examined the results of depth jumping programs to determine: (1) whether certain depth jumping routines, when combined with weight training, are better than others; and (2) the effect of depth jumping on athletes already in training. Results indicated that depth jumping is effective, but no more so than regular jumping routines.…
Mechanography during the vertical jump test allows for evaluation of force-time variables reflecting jump execution, which may enhance screening for functional deficits that reduce physical performance and determining mechanistic causes underlying performance changes. However, utility of jump mechan...
Gravity current jump conditions, revisited
Ungarish, Marius; Hogg, Andrew J.
2016-11-01
Consider the flow of a high-Reynolds-number gravity current of density ρc in an ambient fluid of density ρa in a horizontal channel z ∈ [ 0 , H ] , with gravity in - z direction. The motion is often modeled by a two-layer formulation which displays jumps (shocks) in the height of the interface, in particular at the leading front of the dense layer. Various theoretical models have been advanced to predict the dimensionless speed of the jump, Fr = U /√{g' h } ; g' , h are reduced gravity and jump height. We revisit this problem and using the Navier-Stokes equations, integrated over a control volume embedding the jump, derive balances of mass and momentum fluxes. We focus on understanding the closures needed to complete this model and we show the vital need to understand the pressure head losses over the jump, which we show can be related to the vorticity fluxes at the boundaries of the control volume. Our formulation leads to two governing equations for three dimensionless quantities. Closure requires one further assumption, depending on which we demonstrate that previous models for gravity current fronts and internal bores can be recovered. This analysis yield new insights into existing results, and also provides constraints for potential new formulae.
Coalescence-induced nanodroplet jumping
Cha, Hyeongyun; Xu, Chenyu; Sotelo, Jesus; Chun, Jae Min; Yokoyama, Yukihiro; Enright, Ryan; Miljkovic, Nenad
2016-10-01
Water vapor condensation on superhydrophobic surfaces has received much attention in recent years due to the ability of such surfaces to shed microscale water droplets via coalescence-induced droplet jumping, resulting in heat transfer, anti-icing, and self-cleaning performance enhancement. Here we report the coalescence-induced removal of water nanodroplets (R ≈500 nm ) from superhydrophobic carbon nanotube (CNT) surfaces. The two-droplet coalescence time is measured for varying droplet Ohnesorge numbers, confirming that coalescence prior to jumping is governed by capillary-inertial dynamics. By varying the conformal hydrophobic coating thickness on the CNT surface, the minimum jumping droplet radius is shown to increase with increasing solid fraction and decreasing apparent advancing contact angle, allowing us to explore both hydrodynamic limitations stemming from viscous dissipation and surface adhesion limitations. We find that, even for the smallest nanostructure length scale (≤100 nm) and lowest surface adhesions, nonideal surface interactions and the evolved droplet morphology play defining roles in limiting the minimum size for jumping on real surfaces. The outcomes of this work demonstrate the ability to passively shed nanometric water droplets, which has the potential to further increase the efficiency of systems that can harness jumping droplets for a wide range of energy and water applications.
Shima, Hiroyuki
2012-11-01
The tree-based rope swing is a popular recreational facility, often installed in outdoor areas. Hanging from a rope, users drop from a high platform and then swing at great speed like ‘Tarzan’, finally jumping ahead to land on the ground. The question naturally arises, how far can Tarzan jump using the swing? In this paper, I present an introductory analysis of the mechanics of the Tarzan swing, a large pendulum-like swing with Tarzan himself attached as weight. This enables determination of how much further forward Tarzan can jump using a given swing apparatus. The discussion is based on elementary mechanics and is, therefore, expected to provide rich opportunities for investigations using analytic and numerical methods.
Shima, Hiroyuki
2012-01-01
The tree-based rope swing is a popular recreation facility, often installed in outdoor areas, giving pleasure to thrill-seekers. In the setting, one drops down from a high platform, hanging from a rope, then swings at a great speed like "Tarzan", and finally jumps ahead to land on the ground. The question now arises: How far can Tarzan jump by the swing? In this article, I present an introductory analysis of the Tarzan swing mechanics, a big pendulum-like swing with Tarzan himself attached as weight. The analysis enables determination of how farther forward Tarzan can jump using a given swing apparatus. The discussion is based on elementary mechanics and, therefore, expected to provide rich opportunities for investigations using analytic and numerical methods.
Alzheimer's Deaths Jump 55 Percent: CDC
... page: https://medlineplus.gov/news/fullstory_165941.html Alzheimer's Deaths Jump 55 Percent: CDC More patients also ... News) -- As more baby boomers age, deaths from Alzheimer's disease have jumped 55 percent, and in a ...
Inherent enumerability of strong jump-traceability
Diamondstone, David; Turetsky, Daniel
2011-01-01
We show that every strongly jump-traceable set obeys every benign cost function. Moreover, we show that every strongly jump-traceable set is computable from a computably enumerable strongly jump-traceable set. This allows us to generalise properties of c.e.\\ strongly jump-traceable sets to all such sets. For example, the strongly jump-traceable sets induce an ideal in the Turing degrees; the strongly jump-traceable sets are precisely those that are computable from all superlow Martin-L\\"{o}f random sets; the strongly jump-traceable sets are precisely those that are a base for $\\text{Demuth}_{\\text{BLR}}$-randomness; and strong jump-traceability is equivalent to strong superlowness.
Model for polygonal hydraulic jumps
DEFF Research Database (Denmark)
Martens, Erik Andreas; Watanabe, Shinya; Bohr, Tomas
2012-01-01
) near the free surface in the jump region. The model consists of mass conservation and radial force balance between hydrostatic pressure and viscous stresses on the roller surface. In addition, we consider the azimuthal force balance, primarily between pressure and viscosity, but also including...
Jumping property of Lyapunov values
Institute of Scientific and Technical Information of China (English)
毛锐; 王铎
1996-01-01
A sufficient condition for fcth Lyapunov value to be zero for planar polynomial vector fields is given, which extends the result of "jumping property’ of Lyapunov values obtained by Wang Duo to more general cases. A concrete example that the origin cannot be weak focus of order 1, 2, 4, 5, 8 is presented.
A jump forwards with mathematics and physics
A. Heck; P. Uylings
2011-01-01
We jump on human body motions such as bouncing on a jumping stick, hopping, and making kangaroo jumps. Students can record the movements with a digital camera and use their video clips to investigate the motions with suitable video analysis and modelling software. We discuss some mathematical models
Strawberry Shortcake and Other Jumping Rope Ideas.
Adams, Polly K.; Taylor, Michaell K.
Information, guidelines, and activities for jumping rope are given. A short history of jumping rope explains how it evolved from a spring ritual for men to a play activity involving mostly young girls. Physical and cultural reasons are given as to why jumping rope has been more a sport for girls than for boys. Research studies are noted which show…
Strawberry Shortcake and Other Jumping Rope Ideas.
Adams, Polly K.; Taylor, Michaell K.
Information, guidelines, and activities for jumping rope are given. A short history of jumping rope explains how it evolved from a spring ritual for men to a play activity involving mostly young girls. Physical and cultural reasons are given as to why jumping rope has been more a sport for girls than for boys. Research studies are noted which show…
Mesopause jumps at Antarctic latitudes
Lübken, Franz-Josef; Höffner, Josef; Becker, Erich; Latteck, Ralph; Murphy, Damian
2016-04-01
Recent high resolution temperature measurements by resonance lidar at Davis (69°S) occasionally showed a sudden mesopause altitude increase by ˜5 km and an associated mesopause temperature decrease by ˜10 K. We present further observations which are closely related to this 'mesopause jump', namely the increase of mean height of polar mesospheric summer echoes (PMSE) observed by a VHF radar, very strong westward winds in the upper mesosphere measured by an MF radar, and relatively large eastward winds in the stratosphere taken from reanalysis. We compare to similar observations in the Northern Hemisphere, namely at ALOMAR (69°N) where such mesopause jumps have never been observed. We present a detailed explanation of mesopause jumps. They occur only when stratospheric winds are moderately eastward and mesospheric winds are very large (westward). Under these conditions, gravity waves with comparatively large eastward phase Speeds can pass the stratosphere and propagate to the lower thermosphere because their vertical wavelengths in the mesosphere are rather large which implies reduced dynamical stability. When finally breaking in the lower thermosphere, these waves drive an enhanced residual circulation that causes a cold and high-altitude mesopause. The conditions for a mesopause jump occur only in the Southern Hemisphere (SH) and are associated with the late breakdown of the polar vortex. Mesopause jumps are primarily, but not only, observed prior and close to solstice. We also show that during the onset of PMSE in the SH, stratospheric zonal winds are still eastward (up to 30 m/s), and that the onset is not closely related to the Transition of the stratospheric circulation.
Farber, M S; Farber, Michael S.; Levine, Jerome P.
1994-01-01
We study the eta-invariant, defined by Atiyah-Patodi-Singer a real valued invariant of an oriented odd-dimensional Riemannian manifold equipped with a unitary representation of its fundamental group. When the representation varies analytically, the corresponding eta-invariant may have an integral jump, known also as the spectral flow. The main result of the paper establishes a formula for this spectral jump in terms of the signatures of some homological forms, defined naturally by the path of representations. These signatures may also be computed by means of a spectral sequence of Hermitian forms,defined by the deformation data. Our theorem on the spectral jump has a generalization to arbitrary analytic families of self-adjoint elliptic operators. As an application we consider the problem of homotopy invariance of the rho-invariant. We give an intrinsic homotopy theoretic definition of the rho-invariant, up to indeterminacy in the form of a locally constant function on the space of unitary representations. In...
Price jumps on European stock markets
Directory of Open Access Journals (Sweden)
Jan Hanousek
2014-03-01
Full Text Available We analyze the dynamics of price jumps and the impact of the European debt crisis using the high-frequency data reported by selected stock exchanges on the European continent during the period January 2008 to June 2012. We employ two methods to identify price jumps: Method 1 minimizes the probability of false jump detection (the Type-II Error-Optimal price jump indicator and Method 2 maximizes the probability of successful jump detection (the Type-I Error-Optimal price jump indicator. We show that individual stock markets exhibited differences in price jump intensity before and during the crisis. We also show that in general the variance of price jump intensity could not be distinguished as different in the pre-crisis period from that during the crisis. Our results indicate that, contrary to common belief, the intensity of price jumps does not uniformly increase during a period of financial distress. However, there do exist differences in price jump dynamics across stock markets and investors have to model emerging and mature markets differently to properly reflect their individual dynamics.
Directory of Open Access Journals (Sweden)
Santosh N. Kabadi
2005-01-01
Full Text Available The concept of Δ-matroid is a nontrivial, proper generalization of the concept of matroid and has been further generalized to the concept of jump system. In this paper, we show that jump systems are, in some sense, equivalent to Δ-matroids. Using this equivalence and the Δ-matroid theory, we give simple proofs and extensions of many of the results on jump systems.
Time change, jumping measure and Feller measure
He, Ping
2007-01-01
In this paper, we shall investigate some potential theory for time change of Markov processes. Under weak duality, it is proved that the jumping measure and Feller measure are actually independent of time change, and the jumping measure of a time changed process induced by a PCAF supported on $V$ coincides with the sum of the Feller measure on $V$ and the trace of the original jumping measure on $V$.
The aerodynamics of jumping rope
Aristoff, Jeffrey; Stone, Howard
2011-03-01
We present the results of a combined theoretical and experimental investigation of the motion of a rotating string that is held at both ends (i.e. a jump rope). In particular, we determine how the surrounding fluid affects the shape of the string at high Reynolds numbers: the string bends toward the axis of rotation, thereby reducing its total drag. We derive a pair of coupled non-linear differential equations that describe the shape, the numerical solution of which compares well with asymptotic approximations and experiments. Implications for successful skipping will be discussed.
Dynamic jump intensities and risk premiums
DEFF Research Database (Denmark)
Christoffersen, Peter; Ornthanalai, Chayawat; Jacobs, Kris
2012-01-01
We build a new class of discrete-time models that are relatively easy to estimate using returns and/or options. The distribution of returns is driven by two factors: dynamic volatility and dynamic jump intensity. Each factor has its own risk premium. The models significantly outperform standard...... models without jumps when estimated on S&P500 returns. We find very strong support for time-varying jump intensities. Compared to the risk premium on dynamic volatility, the risk premium on the dynamic jump intensity has a much larger impact on option prices. We confirm these findings using joint...... estimation on returns and large option samples....
Laminar circular hydraulic jumps without separation
Dasgupta, Ratul; Tomar, Gaurav; Govindarajan, Rama
2009-11-01
The traditional inviscid criterion for the occurrence of a planar, standing hydraulic jump is to have the Froude number decrease downstream and go through a value of 1 at some location. Here, upstream propagating, small-amplitude, long, non-dispersive gravity waves are trapped, and non-linear steepening is said to result in a near-discontinuous height profile, but it is not clear how. Such a condition on the Froude number is shown in the present axisymmetric Navier-Stokes computations to hold for a circular jump as well. The relevance of non-linear steepening to a circular jump is therefore a question we wish to answer. In circular jumps, moreover, a region of recirculation is usually observed underneath the jump, underlining the importance of viscosity in this process. This led Tani (J. Phys. Soc. Japan, 1949) to hypothesise that boundary-layer separation was the cause of the circular jump. This hypothesis has been debated extensively and the possibility of circular jumps without separation hinted at. In our simulations, we are able to obtain circular hydraulic jumps without any flow separation. This, and the necessity or otherwise of viscosity in jump formation will be discussed.
A Molecular Jump Mechanism of Water Reorientation
National Research Council Canada - National Science Library
Damien Laage; James T. Hynes
2006-01-01
.... This water reorientation mechanism involves large-amplitude angular jumps, rather than the commonly accepted sequence of small diffusive steps, and therefore calls for reinterpretation of many...
Kinematics and Kinetics of Squats, Drop Jumps and Imitation Jumps of Ski Jumpers.
Pauli, Carole A; Keller, Melanie; Ammann, Fabian; Hübner, Klaus; Lindorfer, Julia; Taylor, William R; Lorenzetti, Silvio
2016-03-01
Squats, drop jumps, and imitation jumps are commonly used training exercises in ski jumping to enhance maximum force, explosive force, and sport-specific skills. The purpose of this study was to evaluate the kinetics and kinematics of training exercises in ski jumping and to find objective parameters in training exercises that most correlate with the competition performance of ski jumpers. To this end, barbell squats, drop jumps, and imitation jumps were measured in a laboratory environment for 10 elite ski jumpers. Force and motion data were captured, and the influence of maximum vertical force, force difference, vertical take-off velocity, knee moments, knee joint power, and a knee valgus/varus index was evaluated and correlated with their season jump performance. The results indicate that, especially for the imitation jumps, a good correlation exists between the vertical take-off velocity and the personal jump performance on the hill (R = 0.718). Importantly, however, the more the athletes tended toward a valgus knee alignment during the measured movements, the worse their performance (R = 0.729 imitation jumps; R = 0.685 squats). Although an evaluation of the athletes' lower limb alignment during competitive jumping on the hill is still required, these preliminary data suggest that performance training should additionally concentrate on improving knee alignment to increase ski jumping performance.
Electroencephalographic recordings during parachute jump sessions.
Gauthier, P; Jouffray, L; Rodi, M; Gottesmann, C
1980-04-01
Electroencephalographic (EEG) recordings of experienced parachutists were done by means of telemetry before, during, and after jumps of up to 3500m. During free-fall and after stabilization, alpha rhythm was recorded from several alpha reactive subjects when they closed their eyes. No pathological EEG recordings were obtained during the different phases of the jump.
Jump Detection in the Danish Stock Market
DEFF Research Database (Denmark)
Høg, Esben
2002-01-01
It is well known in financial economics that stock market return data are often modelled by a diffusion process with some regular drift function. Occasionally, however, sudden changes or jumps occur in the return data. Wavelet scaling methods are used to detect jumps and cusps in stock market...
Rope Jumping: A Preliminary Developmental Study.
Wickstrom, Ralph L.
The basic movement pattern used in skilled individual rope jumping performance was determined and used as a model against which to evaluate the rope jumping form used by children at various levels of skills development. The techniques of adults and nursery school children were filmed and analyzed. The specific causes of unsuccessful attempts were…
Separation and pattern formation in hydraulic jumps
DEFF Research Database (Denmark)
Bohr, Tomas; Ellegaard, C.; Hansen, A. Espe;
1998-01-01
We present theory and experiments on the circular hydraulic jump in the stationary regime. The theory can handle the situation in which the fluid flows over an edge far away from the jump. In the experiments the external height is controlled, and a series of transitions in the flow structure appe...
Internal hydraulic jumps with large upstream shear
Ogden, Kelly; Helfrich, Karl
2015-11-01
Internal hydraulic jumps in approximately two-layered flows with large upstream shear are investigated using numerical simulations. The simulations allow continuous density and velocity profiles, and a jump is forced to develop by downstream topography, similar to the experiments conducted by Wilkinson and Wood (1971). High shear jumps are found to exhibit significantly more entrainment than low shear jumps. Furthermore, the downstream structure of the flow has an important effect on the jump properties. Jumps with a slow upper (inactive) layer exhibit a velocity minimum downstream of the jump, resulting in a sub-critical downstream state, while flows with the same upstream vertical shear and a larger barotropic velocity remain super-critical downstream of the jump. A two-layer theory is modified to account for the vertical structure of the downstream density and velocity profiles and entrainment is allowed through a modification of the approach of Holland et al. (2002). The resulting theory can be matched reasonably well with the numerical simulations. However, the results are very sensitive to how the downstream vertical profiles of velocity and density are incorporated into the layered model, highlighting the difficulty of the two layer approximation when the shear is large.
Strong jump traceability and Demuth randomness
Greenberg, Noam
2011-01-01
We solve the covering problem for Demuth randomness, showing that a computably enumerable set is computable from a Demuth random set if and only if it is strongly jump-traceable. We show that on the other hand, the class of sets which form a base for Demuth randomness is a proper subclass of the class of strongly jump-traceable sets.
Stochastic stability properties of jump linear systems
Feng, Xiangbo; Loparo, Kenneth A.; Ji, Yuandong; Chizeck, Howard J.
1992-01-01
Jump linear systems are defined as a family of linear systems with randomly jumping parameters (usually governed by a Markov jump process) and are used to model systems subject to failures or changes in structure. The authors study stochastic stability properties in jump linear systems and the relationship among various moment and sample path stability properties. It is shown that all second moment stability properties are equivalent and are sufficient for almost sure sample path stability, and a testable necessary and sufficient condition for second moment stability is derived. The Lyapunov exponent method for the study of almost sure sample stability is discussed, and a theorem which characterizes the Lyapunov exponents of jump linear systems is presented.
A review on the basketball jump shot.
Okazaki, Victor H A; Rodacki, André L F; Satern, Miriam N
2015-06-01
The ability to shoot an effective jump shot in the sport of basketball is critical to a player's success. In an attempt to better understand the aspects related to expert performance, researchers have investigated successful free throws and jump shots of various basketball players and identified movement variables that contribute to their success. The purpose of this study was to complete a systematic review of the scientific literature on the basketball free throw and jump shot for the purpose of revealing the critical components of shooting that coaches, teachers, and players should focus on when teaching, learning, practising, and performing a jump shot. The results of this review are presented in three sections: (a) variables that affect ball trajectory, (b) phases of the jump shot, and
Usefulness of the jump-and-reach test in assessment of vertical jump performance.
Menzel, Hans-Joachim; Chagas, Mauro H; Szmuchrowski, Leszek A; Araujo, Silvia R; Campos, Carlos E; Giannetti, Marcus R
2010-02-01
The objective was to estimate the reliability and criterion-related validity of the Jump-and-Reach Test for the assessment of squat, countermovement, and drop jump performance of 32 male Brazilian professional volleyball players. Performance of squat, countermovement, and drop jumps with different dropping heights was assessed on the Jump-and-Reach Test and the measurement of flight time, then compared across different jump trials. The very high reliability coefficients of both assessment methods and the lower correlation coefficients between scores on the assessments indicate a very high consistency of each method but only moderate covariation, which means that they measure partly different items. As a consequence, the Jump-and-Reach Test has good ecological validity in situations when reaching height during the flight phase is critical for performance (e.g., basketball and volleyball) but only limited accuracy for the assessment of vertical impulse production with different jump techniques and conditions.
Jumping from the Brooklyn Bridge.
Kurtz, R J; Pizzi, W F; Richman, H; Tiefenbrun, J
1987-07-01
In an attempt to identify factors contributing to survival of free fall and impact, we evaluated the records of four patients who survived a jump from the Brooklyn Bridge into the East River in New York Harbor between 1977 and 1985. All four patients were male and ranged in age from 22 to 67 years. They had free falls of between 41.0 and 48.8 meters. All of the patients were brought to the hospital within 24 minutes of entering the water. Three of the four had emergency surgical treatment and the fourth patient had only minor injuries. All four patients survived the suicide attempts. The length of the hospital stay ranged from two to 26 days.
Directory of Open Access Journals (Sweden)
Gal Ribak
Full Text Available To return to their feet, inverted click-beetles (Elateridae jump without using their legs. When a beetle is resting on its dorsal side, a hinge mechanism is locked to store elastic energy in the body and releases it abruptly to launch the beetle into the air. While the functional morphology of the jumping mechanism is well known, the level of control that the beetle has over this jumping technique and the mechanical constraints governing the jumps are not entirely clear. Here we show that while body rotations in air are highly variable, the jumps are morphologically constrained to a constant "takeoff" angle (79.9°±1.56°, n = 9 beetles that directs 98% of the jumping force vertically against gravity. A physical-mathematical model of the jumping action, combined with measurements from live beetle, imply that the beetle may control the speed at takeoff but not the jumping angle. In addition, the model shows that very subtle changes in the exact point of contact with the ground can explain the vigorous rotations of the body seen while the beetle is airborne. These findings suggest that the evolution of this unique non-legged jumping mechanism resulted in a jumping technique that is capable of launching the body high into the air but it is too constrained and unstable to allow control of body orientation at landing.
Realized Jump Risk and Equity Return in China
Directory of Open Access Journals (Sweden)
Guojin Chen
2014-01-01
Full Text Available We utilize the realized jump components to explore a new jump (including nonsystematic jump and systematic jump risk factor model. After estimating daily realized jumps from high-frequency transaction data of the Chinese A-share stocks, we calculate monthly jump size, monthly jump standard deviation, and monthly jump arrival rate and then use those monthly jump factors to explain the return of the following month. Our empirical results show that the jump tail risk can explain the equity return. For the large capital-size stocks, large cap stock portfolios, and index, one-month lagged jump risk factor significantly explains the asset return variation. Our results remain the same even when we add the size and value factors in the robustness tests.
Bubble visualization in a simulated hydraulic jump
Witt, Adam; Shen, Lian
2013-01-01
This is a fluid dynamics video of two- and three-dimensional computational fluid dynamics simulations carried out at St. Anthony Falls Laboratory. A transient hydraulic jump is simulated using OpenFOAM, an open source numerical solver. A Volume of Fluid numerical method is employed with a realizable k-epsilon turbulence model. The goal of this research is to model the void fraction and bubble size in a transient hydraulic jump. This fluid dynamics video depicts the air entrainment characteristics and bubble behavior within a hydraulic jump of Froude number 4.82.
The Crown Bite Jumping Herbst.
Owen, Reuel
2003-01-01
The Crown Bite Jumping Herbst Appliance is evaluated and combined with Straight Wire Arch Fixed Orthodontics in treatment of Class II, Division I malocclusions. This article will evaluate a combined orthodontic approach of "straightening teeth" and an orthognathic approach of "moving jaws or making skeletal changes." Orthodontic treatment cannot be accomplished well without establishing a healthy temporomandibular joint. This is defined by Keller as a joint that is "noiseless, painless and has a normal range of motion without deviation and deflection." It is not prudent to separate orthodontic treatment as its own entity without being aware of the changes in the temporomandibular joint before, during and after treatment. In other words, "If you're doing orthodontics you're doing TMJ treatment." One should treat toward a healthy, beautiful face asking, "Will proposed treatment achieve this goal?" Treatment should be able to be carried out in an efficient manner, minimizing treatment time, be comfortable and affordable for the patient, and profitable for the dentist. The finished treatment should meet Andrews' Six Keys of Occlusion, or Loudon's Twelve Commandments. Above all, do no harm to the patient. We think that a specific treatment plan can embrace these tenets. The focus will be to show Class II treatment using a modified Herbst Appliance and fixed straight wire orthodontics.
Volatility jumps and their economic determinants
DEFF Research Database (Denmark)
Caporin, Massimiliano; Rossi, Eduardo; Santucci de Magistris, Paolo
that there is a positive probability of jumps in volatility. A common factor in the volatility jumps is shown to be related to a set of financial covariates (such as variance risk premium, S&P500 volume, credit-default swap, and federal fund rates). The credit-default swap on US banks and variance risk premium have...... predictive power on expected jump moves, thus confirming the common interpretation that sudden and large increases in equity volatility can be anticipated by credit deterioration of the US bank sector as well as changes in the market expectations of future risks. Finally, the model is extended to incorporate...... the credit-default swap and the variance risk premium in the dynamics of the jump size and intensity....
Ruse, Karen; Davison, Aidan; Bridle, Kerry
2015-10-22
Thoroughbred jump racing sits in the spotlight of contemporary welfare and ethical debates about horse racing. In Australia, jump racing comprises hurdle and steeplechase races and has ceased in all but two states, Victoria and South Australia. This paper documents the size, geography, composition, and dynamics of Australian jump racing for the 2012, 2013, and 2014 seasons with a focus on debate about risks to horses. We found that the majority of Australian jump racing is regional, based in Victoria, and involves a small group of experienced trainers and jockeys. Australian jump horses are on average 6.4 years of age. The jump career of the majority of horses involves participating in three or less hurdle races and over one season. Almost one quarter of Australian jump horses race only once. There were ten horse fatalities in races over the study period, with an overall fatality rate of 5.1 fatalities per 1000 horses starting in a jump race (0.51%). There was significant disparity between the fatality rate for hurdles, 0.75 fatalities per 1000 starts (0.075%) and steeplechases, 14 fatalities per 1000 starts (1.4%). Safety initiatives introduced by regulators in 2010 appear to have significantly decreased risks to horses in hurdles but have had little or no effect in steeplechases. Our discussion considers these Animals 2015, 5 1073 data in light of public controversy, political debate, and industry regulation related to jump horse safety.
Jump Horse Safety: Reconciling Public Debate and Australian Thoroughbred Jump Racing Data, 2012–2014
Directory of Open Access Journals (Sweden)
Karen Ruse
2015-10-01
Full Text Available Thoroughbred jump racing sits in the spotlight of contemporary welfare and ethical debates about horse racing. In Australia, jump racing comprises hurdle and steeplechase races and has ceased in all but two states, Victoria and South Australia. This paper documents the size, geography, composition, and dynamics of Australian jump racing for the 2012, 2013, and 2014 seasons with a focus on debate about risks to horses. We found that the majority of Australian jump racing is regional, based in Victoria, and involves a small group of experienced trainers and jockeys. Australian jump horses are on average 6.4 years of age. The jump career of the majority of horses involves participating in three or less hurdle races and over one season. Almost one quarter of Australian jump horses race only once. There were ten horse fatalities in races over the study period, with an overall fatality rate of 5.1 fatalities per 1000 horses starting in a jump race (0.51%. There was significant disparity between the fatality rate for hurdles, 0.75 fatalities per 1000 starts (0.075% and steeplechases, 14 fatalities per 1000 starts (1.4%. Safety initiatives introduced by regulators in 2010 appear to have significantly decreased risks to horses in hurdles but have had little or no effect in steeplechases. Our discussion considers these Animals 2015, 5 1073 data in light of public controversy, political debate, and industry regulation related to jump horse safety.
Portfolio Selection with Jumps under Regime Switching
Directory of Open Access Journals (Sweden)
Lin Zhao
2010-01-01
Full Text Available We investigate a continuous-time version of the mean-variance portfolio selection model with jumps under regime switching. The portfolio selection is proposed and analyzed for a market consisting of one bank account and multiple stocks. The random regime switching is assumed to be independent of the underlying Brownian motion and jump processes. A Markov chain modulated diffusion formulation is employed to model the problem.
Preschool-aged children's jumps: imitation performances.
Labiadh, Lazhar; Ramanantsoa, Marie-Martine; Golomer, Eveline
2010-04-01
Imitative behavior underlaid by perception and action links during children's development in complex locomotor skills has been the object of relatively few studies. In order to explore children's motor coordination modes, 130 children divided into five age groups from 3.5 to 7.5 years were instructed to imitate jumping tasks in spontaneous motor situation and in various imitative contexts by an adult providing verbal orders and gestural demonstrations. Their conformity to the model, stability and variability scores were coded from a video analysis when they performed jumps with obstacles. To evaluate their postural-motor control level, the durations of the preparatory phase and jumping flights were also timed. Results showed that all age groups generated the demonstrator's goal but not necessarily the same coordination modes of jumping. In imitation with temporal proximity, the model helped the youngest age groups to adopt his coordination modes and stabilized only the oldest age groups' performances starting from 5.5 years old, without effect on learning imitation. Differences between the youngest and oldest children in the jump duration suggested that the reproduction of a complex motor activity such as jumping with a one foot take-off would require resolution and adjustment of main postural stability.
Performance analysis of jump-gliding locomotion for miniature robotics.
Vidyasagar, A; Zufferey, Jean-Christohphe; Floreano, Dario; Kovač, M
2015-03-26
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.
Jump Horse Safety: Reconciling Public Debate and Australian Thoroughbred Jump Racing Data, 2012–2014
Ruse, Karen; Davison, Aidan; Bridle, Kerry
2015-01-01
Simple Summary This paper documents the dynamics of Australian thoroughbred jump racing in the 2012, 2013, and 2014 seasons with the aim of informing debate about risks to horses and the future of this activity. We conclude that the safety of Australian jump racing has improved in recent years but that steeplechases are considerably riskier for horses than hurdle races. Abstract Thoroughbred jump racing sits in the spotlight of contemporary welfare and ethical debates about horse racing. In Australia, jump racing comprises hurdle and steeplechase races and has ceased in all but two states, Victoria and South Australia. This paper documents the size, geography, composition, and dynamics of Australian jump racing for the 2012, 2013, and 2014 seasons with a focus on debate about risks to horses. We found that the majority of Australian jump racing is regional, based in Victoria, and involves a small group of experienced trainers and jockeys. Australian jump horses are on average 6.4 years of age. The jump career of the majority of horses involves participating in three or less hurdle races and over one season. Almost one quarter of Australian jump horses race only once. There were ten horse fatalities in races over the study period, with an overall fatality rate of 5.1 fatalities per 1000 horses starting in a jump race (0.51%). There was significant disparity between the fatality rate for hurdles, 0.75 fatalities per 1000 starts (0.075%) and steeplechases, 14 fatalities per 1000 starts (1.4%). Safety initiatives introduced by regulators in 2010 appear to have significantly decreased risks to horses in hurdles but have had little or no effect in steeplechases. Our discussion considers these data in light of public controversy, political debate, and industry regulation related to jump horse safety. PMID:26506396
Jumping to conclusions in schizophrenia
Directory of Open Access Journals (Sweden)
Evans SL
2015-07-01
Full Text Available Simon L Evans,1 Bruno B Averbeck,2 Nicholas Furl31School of Psychology, University of Sussex, Brighton, East Sussex, UK; 2Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health, Bethesda, MD, USA; 3Department of Psychology, Royal Holloway, University of London, Egham, Surrey, UKAbstract: Schizophrenia is a mental disorder associated with a variety of symptoms, including hallucinations, delusions, social withdrawal, and cognitive dysfunction. Impairments on decision-making tasks are routinely reported: evidence points to a particular deficit in learning from and revising behavior following feedback. In addition, patients tend to make hasty decisions when probabilistic judgments are required. This is known as “jumping to conclusions” (JTC and has typically been demonstrated by presenting participants with colored beads drawn from one of two “urns” until they claim to be sure which urn the beads are being drawn from (the proportions of colors vary in each urn. Patients tend to make early decisions on this task, and there is evidence to suggest that a hasty decision-making style might be linked to delusion formation and thus be of clinical relevance. Various accounts have been proposed regarding what underlies this behavior. In this review, we briefly introduce the disorder and the decision-making deficits associated with it. We then explore the evidence for each account of JTC in the context of a wider decision-making deficit and then go on to summarize work exploring JTC in healthy controls using pharmacological manipulations and functional imaging. Finally, we assess whether JTC might have a role in therapy.Keywords: ketamine, decision making, delusions, fMRI, urn task
A biomechanical comparison of the vertical jump, power clean, and jump squat.
MacKenzie, Sasho James; Lavers, Robert J; Wallace, Brendan B
2014-01-01
The purpose of this study was to compare the kinetics, kinematics, and muscle activation patterns of the countermovement jump, the power clean, and the jump squat with the expectation of gaining a better understanding of the mechanism of transfer from the power clean to the vertical jump. Ground reaction forces, electromyography, and joint angle data were collected from 20 trained participants while they performed the three movements. Relative to the power clean, the kinematics of the jump squat were more similar to those of the countermovement jump. The order in which the ankle, knee, and hip began extending, as well as the subsequent pattern of extension, was different between the power clean and countermovement jump. The electromyography data demonstrated significant differences in the relative timing of peak activations in all muscles, the maximum activation of the rectus femoris and biceps femoris, and in the activation/deactivation patterns of the vastus medialis and rectus femoris. The greatest rate of force development during the upward phase of these exercises was generated during the power clean (17,254 [Formula: see text]), which was significantly greater than both the countermovement jump (3836 [Formula: see text]) and jump squat (3517 [Formula: see text]) conditions (P < .001, [Formula: see text]).
The effect of wind on jumping distance in ski jumping--fairness assessed.
Virmavirta, Mikko; Kivekäs, Juha
2012-09-01
The special wind compensation system recently adopted by Fédération Internationale de Ski (FIS; International Ski Federation) to consider the effects of changing wind conditions has caused some controversy. Here, the effect of wind on jumping distance in ski jumping was studied by means of computer simulation and compared with the wind compensation factors used by FIS during the World Cup season 2009/2010. The results showed clearly that the effect of increasing head/tail wind on jumping distance is not linear: +17.4 m/-29.1 m, respectively, for a wind speed of 3 m/s. The linear formula used in the trial period of the wind compensation system was found to be appropriate only for a limited range of jumping distances as the gradient of the landing slope slows down the rate of distance change in long jumps.
Filtering and control of stochastic jump hybrid systems
Yao, Xiuming; Zheng, Wei Xing
2016-01-01
This book presents recent research work on stochastic jump hybrid systems. Specifically, the considered stochastic jump hybrid systems include Markovian jump Ito stochastic systems, Markovian jump linear-parameter-varying (LPV) systems, Markovian jump singular systems, Markovian jump two-dimensional (2-D) systems, and Markovian jump repeated scalar nonlinear systems. Some sufficient conditions are first established respectively for the stability and performances of those kinds of stochastic jump hybrid systems in terms of solution of linear matrix inequalities (LMIs). Based on the derived analysis conditions, the filtering and control problems are addressed. The book presents up-to-date research developments and novel methodologies on stochastic jump hybrid systems. The contents can be divided into two parts: the first part is focused on robust filter design problem, while the second part is put the emphasis on robust control problem. These methodologies provide a framework for stability and performance analy...
A locust-inspired miniature jumping robot.
Zaitsev, Valentin; Gvirsman, Omer; Ben Hanan, Uri; Weiss, Avi; Ayali, Amir; Kosa, Gabor
2015-11-25
Unmanned ground vehicles are mostly wheeled, tracked, or legged. These locomotion mechanisms have a limited ability to traverse rough terrain and obstacles that are higher than the robot's center of mass. In order to improve the mobility of small robots it is necessary to expand the variety of their motion gaits. Jumping is one of nature's solutions to the challenge of mobility in difficult terrain. The desert locust is the model for the presented bio-inspired design of a jumping mechanism for a small mobile robot. The basic mechanism is similar to that of the semilunar process in the hind legs of the locust, and is based on the cocking of a torsional spring by wrapping a tendon-like wire around the shaft of a miniature motor. In this study we present the jumping mechanism design, and the manufacturing and performance analysis of two demonstrator prototypes. The most advanced jumping robot demonstrator is power autonomous, weighs 23 gr, and is capable of jumping to a height of 3.35 m, covering a distance of 1.37 m.
Mechanical jumping power in young athletes.
Viitasalo, J T; Osterback, L; Alen, M; Rahkila, P; Havas, E
1987-09-01
Mechanical jumping power was determined for 286 young male athletes representing six sports events and ranging in calendar and skeletal ages from 8.8 to 17.1 and from 7.8 to 18.1 years, respectively. The subjects performed successive maximal vertical jumps on a contact mat for 30 s. The number of jumps and their cumulative flight time after 15 and 30 s were used for calculations of mechanical power. The jumping performances of the young athletes were found to be reproducible from the age of 10-12 years in respect to the angular displacement of the knee and duration of contact. Absolute mechanical power, as well as power related to body weight, increased with calendar and skeletal ages. Of the anthropometric characteristics, the circumference of the thigh and body weight showed the highest correlation with mechanical power; subjects with the greatest thigh circumference and body weight having the lowest mechanical power. The subjects were divided into 'power' (track and field, gymnastics) and 'endurance' (skiing, orienteering) groups. The former reached higher mechanical power values than the latter. Mechanical power for the second 15-s jumping period was on average 4.7% lower than for the first. The events did not differ from each other in respect of the decrease in power.
Nonlinear regimes on polygonal hydraulic jumps
Rojas, Nicolas
2016-11-01
This work extends previous leading and higher order results on the polygonal hydraulic jump in the framework of inertial lubrication theory. The rotation of steady polygonal jumps is observed in the transition from one wavenumber to the next one, induced by a change in height of an external obstacle near the outer edge. In a previous publication, the study of stationary polygons is considered under the assumption that the reference frame rotates with the polygons when the number of corners change, in order to preserve their orientation. In this research work I provide a Hamiltonian approach and the stability analysis of the nonlinear oscillator that describe the polygonal structures at the jump interface, in addition to a perturbation method that enables to explain, for instance, the diversity of patterns found in experiments. GRASP, Institute of Physics, University of Liege, Belgium.
Aerodynamic Jump for Long Rod Penetrators
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Mark L. Bundy
2000-04-01
Full Text Available Aerodynamic jump for a non-spinning kinetic energy penetrator is neither a discontinuous change in the ,direction of motion at the origin of free night, nor is it the converse, i.e. a cumulativer~direc4on over a domain of infinite extent. Rather aerodynamic jump, for such a projectile, is a localised redirection of the centre of gravity motion, caused ~ the force of lift due to yaw over ther4latively short region from entry into free flight until the yaw reaches its first maximum. The primary objective of this paper is to provide answtfrs to the questions like what is aerodynamic jump, what liauses it, !lnd wh~t aspects df the flight trajectory does it refer to, or account for .
Institute of Scientific and Technical Information of China (English)
魏二玲; 刘颜佩
2004-01-01
For a graph G of size ε≥1 and its edge-induced subgraphs H1 and H2 of size γ(1 < γ < ε), H1 is said to be obtained from H2 by an edge jump if there exist four distinct vertices u, v, ω and x in G such that (u,v)∈E(H2), (ω,x)∈E(G) - E(H2) and H1=H2 - (u, v) + (ω, x). In this article, the γ-jump graphs(r≥3) are discussed. A graph H is said to be an γ-jump graph of G if its vertices correspond to the edge induced graph of size γ in G and two vertices are adjacent if and only if one of the two corresponding subgraphs can be obtained from the other by an edge jump. For k≥2, the k-th iterated γ-jump graph Jrk(G) is defined as Jγ(Jγk-1 (G)), where Jγ1 (G) = Jγ(G). An infinite sequence {Gi} of graphs is planar if every graph Gi is planar. It is shown that there does not exist a graph G for which the sequence {J3k(G)} is planar, where k is any positive integer. Meanwhile, lim gen(J3k(G)) =∞, where gen(G) denotes the genus of a graph G, if the sequence k→∞J3k(G) is defined for every positive integer k. As for the 4-jump graph of a graph G,{J4k(G)} is planar if and only if G = C5. For γ≥5, whether the fix graph of the sequence {Jγk(G))exists is determined.
Spectral Analysis of Diffusions with Jump Boundary
Kolb, Martin
2011-01-01
In this paper we consider one-dimensional diffusions with constant coefficients in a finite interval with jump boundary and a certain deterministic jump distribution. We use coupling methods in order to identify the spectral gap in the case of a large drift and prove that that there is a threshold drift above which the bottom of the spectrum no longer depends on the drift. As a Corollary to our result we are able to answer two questions concerning elliptic eigenvalue problems with non-local boundary conditions formulated previously by Iddo Ben-Ari and Ross Pinsky.
Aerodynamic Jump for Long Rod Penetrators
Mark L. Bundy
2000-01-01
Aerodynamic jump for a non-spinning kinetic energy penetrator is neither a discontinuous change in the ,direction of motion at the origin of free night, nor is it the converse, i.e. a cumulativer~direc4on over a domain of infinite extent. Rather aerodynamic jump, for such a projectile, is a localised redirection of the centre of gravity motion, caused ~ the force of lift due to yaw over ther4latively short region from entry into free flight until the yaw reaches its first maximum. The primary...
Understanding the Physics of Bungee Jumping
Heck, Andre; Uylings, Peter; Kedzierska, Ewa
2010-01-01
Changing mass phenomena like the motion of a falling chain, the behaviour of a falling elastic bar or spring, and the motion of a bungee jumper surprise many a physicist. In this article we discuss the first phase of bungee jumping, when the bungee jumper falls, but the bungee rope is still slack. In instructional material this phase is often…
2005-01-01
Sarah Dastugue, 11, leaps in the air as Libby Knox, 9, swings a jump rope. The children were participants in Nickelodeon's Worldwide Day of Play celebration at Stennis Space Center (SSC) on Oct. 1. On the day of the event, children all over the world participate in physical activities as part of the celebration.
Understanding the physics of bungee jumping
Heck, A.; Uylings, P.; Kędzierska, E.
2010-01-01
Changing mass phenomena like the motion of a falling chain, the behaviour of a falling elastic bar or spring, and the motion of a bungee jumper surprise many a physicist. In this article we discuss the first phase of bungee jumping, when the bungee jumper falls, but the bungee rope is still slack.
Jumping on the Social Media Bandwagon
Blakeslee, Lori
2012-01-01
Should a school district jump on the social media bandwagon? Yes! Social media provide a low-cost way to communicate school district priorities, influence decision makers, and tell its story without filters. Equally important, social media are where constituents are spending a lot of their time. With more than 800 million members, Facebook is an…
Jumping on the Social Media Bandwagon
Blakeslee, Lori
2012-01-01
Should a school district jump on the social media bandwagon? Yes! Social media provide a low-cost way to communicate school district priorities, influence decision makers, and tell its story without filters. Equally important, social media are where constituents are spending a lot of their time. With more than 800 million members, Facebook is an…
Jumping-droplet electrostatic energy harvesting
Miljkovic, Nenad; Preston, Daniel J.; Enright, Ryan; Wang, Evelyn N.
2014-07-01
Micro- and nanoscale wetting phenomena have been an active area of research due to its potential for improving engineered system performance involving phase change. With the recent advancements in micro/nanofabrication techniques, structured surfaces can now be designed to allow condensing coalesced droplets to spontaneously jump off the surface due to the conversion of excess surface energy into kinetic energy. In addition to being removed at micrometric length scales (˜10 μm), jumping water droplets also attain a positive electrostatic charge (˜10-100 fC) from the hydrophobic coating/condensate interaction. In this work, we take advantage of this droplet charging to demonstrate jumping-droplet electrostatic energy harvesting. The charged droplets jump between superhydrophobic copper oxide and hydrophilic copper surfaces to create an electrostatic potential and generate power during formation of atmospheric dew. We demonstrated power densities of ˜15 pW/cm2, which, in the near term, can be improved to ˜1 μW/cm2. This work demonstrates a surface engineered platform that promises to be low cost and scalable for atmospheric energy harvesting and electric power generation.
DISCONTINUOUS FLOW OF TURBID DENSITY CURRENTS Ⅱ. INTERNAL HYDRAULIC JUMP
Institute of Scientific and Technical Information of China (English)
Jiahua FAN
2005-01-01
Traveling and stationary internal hydraulic jumps in density currents with positive or negative entrainment coefficients were analyzed based on simple assumptions. An expression of internal hydraulic jumps with entrainment coefficients was derived. Experimental data, published in literature, of stationary internal hydraulic jumps in turbid, thermal and saline density currents including measured values of water entrainment were used to compare with theory. Comparison was also made of traveling internal hydraulic jumps between measured data and theory.
Option Valuation with Observable Volatility and Jump Dynamics
DEFF Research Database (Denmark)
Christoffersen, Peter; Feunou, Bruno; Jeon, Yoontae
Under very general conditions, the total quadratic variation of a jump-diffusion process can be decomposed into diffusive volatility and squared jump variation. We use this result to develop a new option valuation model in which the underlying asset price exhibits volatility and jump intensity dy...
Determination of jumps for functions via derivative Gabor series
Institute of Scientific and Technical Information of China (English)
ZHOU Ying-ying; SHI Xian-liang
2009-01-01
Recently, Shi Xianliang and Hu Lan published the method of concentration factors for determination of jumps of functions via MCM conjugate wavelets. Usually, it is difficult to calculate the Hilbert transform of general window functions. The aim of this paper is to discuss determination of jumps for functions based on derivative Gabor series. The results will simplify the calculation of jump values.
Lift-off dynamics in a simple jumping robot
Aguilar, Jeffrey; Wiesenfeld, Kurt; Goldman, Daniel I
2012-01-01
We study vertical jumping in a simple robot comprising an actuated mass-spring arrangement. The actuator frequency and phase are systematically varied to find optimal performance. Optimal jumps occur above and below (but not at) the robot's resonant frequency $f_0$. Two distinct jumping modes emerge: a simple jump which is optimal above $f_0$ is achievable with a squat maneuver, and a peculiar stutter jump which is optimal below $f_0$ is generated with a counter-movement. A simple dynamical model reveals how optimal lift-off results from non-resonant transient dynamics.
Dynamics of Coalescence-Induced Jumping Water Droplets
Miljkovic, Nenad; Enright, Ryan; Wang, Evelyn N
2013-01-01
This fluid dynamics video shows the different interaction mechanisms of coalescence-induced droplet jumping during condensation on a nanostructured superhydrophobic surface. High speed imaging was used to show jumping behavior on superhydrophobic copper oxide and carbon nanotube surfaces. Videos demonstrating multi-jumping droplets, jumping droplet return to the surface, and droplet-droplet electrostatic repulsions were analyzed. Experiments using external electric fields in conjunction with high speed imaging in a custom built experimental chamber were used to show that all coalescence-induced jumping droplets on superhydrophobic surfaces become positively charged upon leaving the surface, which is detailed in the video.
Effect of early training on the jumping technique of horses.
Santamaría, Susana; Bobbert, Maarten F; Back, Willem; Barneveld, Ab; van Weeren, P Rene
2005-03-01
To investigate the effects of early training for jumping by comparing the jumping technique of horses that had received early training with that of horses raised conventionally. 40 Dutch Warmblood horses. The horses were analyzed kinematically during free jumping at 6 months of age. Subsequently, they were allocated into a control group that was raised conventionally and an experimental group that received 30 months of early training starting at 6 months of age. At 4 years of age, after a period of rest in pasture and a short period of training with a rider, both groups were analyzed kinematically during free jumping. Subsequently, both groups started a 1-year intensive training for jumping, and at 5 years of age, they were again analyzed kinematically during free jumping. In addition, the horses competed in a puissance competition to test maximal performance. Whereas there were no differences in jumping technique between experimental and control horses at 6 months of age, at 4 years, the experimental horses jumped in a more effective manner than the control horses; they raised their center of gravity less yet cleared more fences successfully than the control horses. However, at 5 years of age, these differences were not detected. Furthermore, the experimental horses did not perform better than the control horses in the puissance competition. Specific training for jumping of horses at an early age is unnecessary because the effects on jumping technique and jumping capacity are not permanent.
Biomechanical Analysis of the Jump Shot in Basketball
Directory of Open Access Journals (Sweden)
Struzik Artur
2014-10-01
Full Text Available Basketball players usually score points during the game using the jump shot. For this reason, the jump shot is considered to be the most important element of technique in basketball and requires a high level of performance. The aim of this study was to compare the biomechanical characteristics of the lower limbs during a jump shot without the ball and a countermovement jump without an arm swing. The differences between variables provide information about the potential that an athlete can utilise during a game when performing a jump shot. The study was conducted among 20 second-league basketball players by means of a Kistler force plate and the BTS SMART system for motion analysis. The variables measured included the take-off time, mean power, peak power, relative mean power, jump height, maximum landing force and calculated impact ratio. Surprisingly, more advantageous variables were found for the jump shot. This finding suggests a very high performance level in the jump shot in the studied group and a maximum utilisation of their motor abilities. Both types of jumps were characterised by high mean and peak power values and average heights. The high forces at landing, which result in considerable impact ratios, may have prompted the studied group to land softly. Use of the countermovement jump without an arm swing is recommended to assess and predict the progression of player’s jumping ability
Scaled Jump in Gravity-Reduced Virtual Environments.
Kim, MyoungGon; Cho, Sunglk; Tran, Tanh Quang; Kim, Seong-Pil; Kwon, Ohung; Han, JungHyun
2017-04-01
The reduced gravity experienced in lunar or Martian surfaces can be simulated on the earth using a cable-driven system, where the cable lifts a person to reduce his or her weight. This paper presents a novel cable-driven system designed for the purpose. It is integrated with a head-mounted display and a motion capture system. Focusing on jump motion within the system, this paper proposes to scale the jump and reports the experiments made for quantifying the extent to which a jump can be scaled without the discrepancy between physical and virtual jumps being noticed by the user. With the tolerable range of scaling computed from these experiments, an application named retargeted jump is developed, where a user can jump up onto virtual objects while physically jumping in the real-world flat floor. The core techniques presented in this paper can be extended to develop extreme-sport simulators such as parasailing and skydiving.
Capture of Trojans by Jumping Jupiter
Nesvorny, David; Morbidelli, Alessandro
2013-01-01
Jupiter Trojans are thought to be survivors of a much larger population of planetesimals that existed in the planetary region when planets formed. They can provide important constraints on the mass and properties of the planetesimal disk, and its dispersal during planet migration. Here we tested a possibility that the Trojans were captured during the early dynamical instability among the outer planets (aka the Nice model), when the semimajor axis of Jupiter was changing as a result of scattering encounters with an ice giant. The capture occurs in this model when Jupiter's orbit and its Lagrange points become radially displaced in a scattering event and fall into a region populated by planetesimals (that previously evolved from their natal transplanetary disk to ~5 AU during the instability). Our numerical simulations of the new capture model, hereafter jump capture, satisfactorily reproduce the orbital distribution of the Trojans and their total mass. The jump capture is potentially capable of explaining the ...
Sex Differences in Countermovement Jump Phase Characteristics
Directory of Open Access Journals (Sweden)
John J. McMahon
2017-01-01
Full Text Available The countermovement jump (CMJ is commonly used to explore sex differences in neuromuscular function, but previous studies have only reported gross CMJ measures or have partly examined CMJ phase characteristics. The purpose of this study was to explore differences in CMJ phase characteristics between male and female athletes by comparing the force-, power-, velocity-, and displacement-time curves throughout the entire CMJ, in addition to gross measures. Fourteen men and fourteen women performed three CMJs on a force platform from which a range of kinetic and kinematic variables were calculated via forward dynamics. Jump height (JH, reactive strength index modified, relative peak concentric power, and eccentric and concentric displacement, velocity, and relative impulse were all greater for men (g = 0.58–1.79. Relative force-time curves were similar between sexes, but relative power-, velocity-, and displacement-time curves were greater for men at 90%–95% (immediately before and after peak power, 47%–54% (start of eccentric phase and 85%–100% (latter half of concentric phase, and 65%–87% (bottom of countermovement and initial concentric phase of normalized jump time, respectively. The CMJ distinguished between sexes, with men demonstrating greater JH through applying a larger concentric impulse and, thus, achieving greater velocity throughout most of the concentric phase, including take-off.
Quantum jumps of a fluxonium qubit
Vool, U.; Pop, I. M.; Sliwa, K.; Abdo, B.; Brecht, T.; Shankar, S.; Hatridge, M.; Schoelkopf, R. J.; Mirrahimi, M.; Glazman, L.; Devoret, M. H.
2014-03-01
The fluxonium qubit has recently been shown to have energy relaxation time (T1) of the order of 1 ms, limited by quasiparticle dissipation. With the addition of a Josephson Parametric Converter (JPC) to the experiment, trajectories corresponding to quantum jumps between the ground and 1st excited state can be measured, thus allowing the observation of the qubit decay in real time instead of that of an ensemble average. Our measurement fidelity with the JPC is in excess of 98% for an acquisition time of 5 us and we can thus continuously monitor the quantum jumps of the qubit in equilibrium with its environment in a time much shorter than its average relaxation time. We observe in our sample a jump statistics that varies from being completely Poissonian with a long (500 us) mean time in the ground state to being highly non-Poissonian with short (100 us) mean time in the ground state. The changes between these regimes occur on time scales of seconds, minutes and even hours. We have studied this effect and its relation to quasiparticle dynamics by injecting quasiparticles with a short intense microwave pulse and by seeding quasiparticle-trapping vortices with magnetic field. Work supported by: IARPA, ARO, and NSF.
POTENTIAL FOR NON-CONTACT ACL INJURY BETWEEN STEP-CLOSE-JUMP AND HOP-JUMP TASKS
Directory of Open Access Journals (Sweden)
Li-I Wang
2010-03-01
Full Text Available This study aimed to compare the kinematics and kinetics during the landing of hop-jump and step-close-jump movements in order to provide further inferring that the potential risk of ACL injuries. Eleven elite male volleyball players were recruited to perform hop-jump and step-close-jump tasks. Lower extremity kinematics and ground reaction forces during landing in stop-jump tasks were recorded. Lower extremity kinetics was calculated by using an inverse dynamic process. Step-close-jump tasks demonstrated smaller peak proximal tibia anterior shear forces during the landing phase. In step-close-jump tasks, increasing hip joint angular velocity during initial foot-ground contact decreased peak posterior ground reaction force during the landing phase, which theoretically could reduce the risk of ACL injury
Farr, Will M
2011-01-01
Selection among alternative theoretical models given an observed data set is an important challenge in many areas of physics and astronomy. Reversible-jump Markov chain Monte Carlo (RJMCMC) is an extremely powerful technique for performing Bayesian model selection, but it suffers from a fundamental difficulty: it requires jumps between model parameter spaces, but cannot retain a memory of the favored locations in more than one parameter space at a time. Thus, a naive jump between parameter spaces is unlikely to be accepted in the MCMC algorithm and convergence is correspondingly slow. Here we demonstrate an interpolation technique that uses samples from single-model MCMCs to propose inter-model jumps from an approximation to the single-model posterior of the target parameter space. The interpolation technique, based on a kD-tree data structure, is adaptive and efficient in arbitrary dimensions. We show that our technique leads to dramatically improved convergence over naive jumps in an RJMCMC, and compare it ...
Farr, W M; Mandel, I; Stevens, D
2015-06-01
Selection among alternative theoretical models given an observed dataset is an important challenge in many areas of physics and astronomy. Reversible-jump Markov chain Monte Carlo (RJMCMC) is an extremely powerful technique for performing Bayesian model selection, but it suffers from a fundamental difficulty and it requires jumps between model parameter spaces, but cannot efficiently explore both parameter spaces at once. Thus, a naive jump between parameter spaces is unlikely to be accepted in the Markov chain Monte Carlo (MCMC) algorithm and convergence is correspondingly slow. Here, we demonstrate an interpolation technique that uses samples from single-model MCMCs to propose intermodel jumps from an approximation to the single-model posterior of the target parameter space. The interpolation technique, based on a kD-tree data structure, is adaptive and efficient in modest dimensionality. We show that our technique leads to improved convergence over naive jumps in an RJMCMC, and compare it to other proposals in the literature to improve the convergence of RJMCMCs. We also demonstrate the use of the same interpolation technique as a way to construct efficient 'global' proposal distributions for single-model MCMCs without prior knowledge of the structure of the posterior distribution, and discuss improvements that permit the method to be used in higher dimensional spaces efficiently.
The Mechanics and Trajectory Control in Locust Jumping
Institute of Scientific and Technical Information of China (English)
Longbao Han; Zhouyi Wang; Aihong Ji; Zhendong Dai
2013-01-01
Locusts (Locusta migratoria manilensis) are characterised by their flying ability and abiding jump ability.Research on the jumping mechanics and behavior of locusts plays an important role in elucidating the mechanism of hexapod locomotion.The jump gestures of locusts were observed using high-speed video camera at 250 fps.The reaction forces of the hindlegs were measured using two three-dimensional sensors,in case the two hindlegs attached on separated sensor plates.The jump gestures and reaction forces were used to illustrate the locust jumping mechanism.Results show that the trajectory control is achieved by rapid rolling and yawing movements of the locust body,caused by the forelegs,midlegs and hindlegs in different jumping phases.The final jump trajectory was not determined until hind tarsi left platform.The horizontal co-impulse between two hindlegs might play a key role in jump stability and accuracy.Besides,the angle between two hindlegs affects the control of jump trajectory but has a little effect on the elevation angle of a jump,which is controlled mechanically by the initial position of the hindlegs.This research lays the groundwork for the probable design and development of biomimetic robotics.
Promoting balance and jumping skills in children with Down syndrome.
Wang, Wai-Yi; Ju, Yun-Huei
2002-04-01
The purpose of this study was to investigate the changes in balance and qualitative and quantitative jumping performances by 20 children with Down syndrome (3 to 6 years) on jumping lessons. 30 typical children ages 3 to 6 years were recruited as a comparison group. Before the jumping lesson, a pretest was given subjects for balance and jumping skill measures based on the Motor Proficiency and Motor Skill Inventory, respectively. Subjects with Down syndrome received 3 sessions on jumping per week for 6 weeks but not the typical children. Then, a posttest was administered to all subjects. Analysis of covariance showed the pre- and posttest differences on scores for floor walk, beam walk, and horizontal and vertical jumping by subjects with Down syndrome were significantly greater than those for the typical children.
Theoretical Modeling of Internal Hydraulic Jump in Density Currents
Firoozabadi, Bahar; Aryanfar, Asghar; Afshin, Hossein
2013-01-01
In this paper, we propose an analytical framework for internal hydraulic jumps. Density jumps or internal hydraulic jumps occur when a supper critical flow of water discharges into a stagnant layer of water with slightly different density. The approach used here is control volume method which is also used to analyze ordinary hydraulic jumps. The important difference here is that entrainment is taken into account. Using conservation equations with the aid of some simplifying assumptions we come to an equation that gives jump downstream height as function of jump upstream characteristics and the entrainment. To determine the magnitude of downstream height we use an experimental equation for calculating the entrainment. Finally we verify our framework by comparing the height that we gain from the derived equation with some experimental data.
A-jump in horizontal inverted semicircular open channels
Directory of Open Access Journals (Sweden)
I.M.H. Rashwan
2013-12-01
Full Text Available The hydraulic jump is a transitional state from supercritical to subcritical flow. The phenomenon of the hydraulic jump has been widely studied because of its frequent occurrence in nature and because of its uses in many practical applications. In the present study the momentum principle is used to derive an equation expressed the hydraulic jump (A-jump occurred in a short horizontal reach of an inverted semicircular open channel. The derived equation indicates that the initial water depth and the tail water depth (conjugate depths are functions of the critical water depth. Various elements of the hydraulic jump are expressed in dimensionless case. The procedure of dimensionless ratios described in the present paper can be used to determine various elements of A-jump in an inverted semicircular channel when either the discharge and the relative initial depth (or tail water depth is known or the discharge and the relative dissipated energy are known.
A Jump-Diffusion Model with Stochastic Volatility and Durations
DEFF Research Database (Denmark)
Wei, Wei; Pelletier, Denis
Market microstructure theories suggest that the durations between transactions carry information about volatility. This paper puts forward a model featuring stochastic volatility, stochastic conditional duration, and jumps to analyze high frequency returns and durations. Durations affect price...... jumps in two ways: as exogenous sampling intervals, and through the interaction with volatility. We adopt a bivariate Ornstein-Ulenbeck process to model intraday volatility and conditional duration. We develop a MCMC algorithm for the inference on irregularly spaced multivariate processes with jumps....... The algorithm provides smoothed estimates of the latent variables such as spot volatility, conditional duration, jump times, and jump sizes. We apply this model to IBM data and find that volatility and conditional duration are interdependent. We also find that jumps play an important role in return variation...
Robust Stabilization for Uncertain Linear Delay Markow Jump System
Institute of Scientific and Technical Information of China (English)
钟麦英; 汤兵勇; 黄小原
2001-01-01
Markov jump linear systems are defined as a family of linear systems with randomly Markov jumping parameters and are used to model systems subject to failures or changes in structure. The robust stabilization problem of jump linear delay system with umcerratnty was studied. By using of linear matrix inequalities, the existence conditions of robust stabilizing and the state feedback controller designing methods are also presented and proved. Finally, an illustrated example shows the effectiveness of this approach.
Approximation of Jump Diffusions in Finance and Economics
Nicola Bruti-Liberati; Eckhard Platen
2006-01-01
In finance and economics the key dynamics are often specified via stochastic differential equations (SDEs) of jump-diffusion type. The class of jump-diffusion SDEs that admits explicit solutions is rather limited. Consequently, discrete time approximations are required. In this paper we give a survey of strong and weak numerical schemes for SDEs with jumps. Strong schemes provide pathwise approximations and therefore can be employed in scenario analysis, filtering or hedge simulation. Weak sc...
Times and Sizes of Jumps in the Mexican Interest Rate
José Antonio Núñez Mora; Arturo Lorenzo Valdés
2008-01-01
This paper examines the role of jumps in a continuous-time short-term interest rate model for Mexico. A filtering algorithm provides estimates of jumps times and sizes in the time series of Mexican cetes for the 1998-2006 period. The empirical results indicate that the inclusion of jumps in the diffusion model represents a better alternative than not to include them.
Multiobjective Optimization Methodology A Jumping Gene Approach
Tang, KS
2012-01-01
Complex design problems are often governed by a number of performance merits. These markers gauge how good the design is going to be, but can conflict with the performance requirements that must be met. The challenge is reconciling these two requirements. This book introduces a newly developed jumping gene algorithm, designed to address the multi-functional objectives problem and supplies a viably adequate solution in speed. The text presents various multi-objective optimization techniques and provides the technical know-how for obtaining trade-off solutions between solution spread and converg
Planar jumping-drop thermal diodes
Boreyko, Jonathan B.; Zhao, Yuejun; Chen, Chuan-Hua
2011-12-01
Phase-change thermal diodes rectify heat transport much more effectively than solid-state ones, but are limited by either the gravitational orientation or one-dimensional configuration. Here, we report a planar phase-change diode scalable to large areas with an orientation-independent diodicity of over 100, in which water/vapor is enclosed by parallel superhydrophobic and superhydrophilic plates. The thermal rectification is enabled by spontaneously jumping dropwise condensate which only occurs when the superhydrophobic surface is colder than the superhydrophilic surface.
Understanding the physics of bungee jumping
Heck, A; Uylings, P.; Kędzierska, E.
2010-01-01
Changing mass phenomena like the motion of a falling chain, the behaviour of a falling elastic bar or spring, and the motion of a bungee jumper surprise many a physicist. In this article we discuss the first phase of bungee jumping, when the bungee jumper falls, but the bungee rope is still slack. In instructional material this phase is often considered a free fall, but when the mass of the bungee rope is taken into account, the bungee jumper reaches acceleration greater than g. This result i...
Quantifying show jumping horse rider expertise using IMUs.
Patterson, M; Doyle, J; Cahill, E; Caulfield, B; McCarthy Persson, U
2010-01-01
Horse rider ability has long been measured using horse performance, competition results and visual observation. Scientific methods of measuring rider ability on the flat are emerging such as measuring position angles and harmony of the horse-rider system. To date no research has quantified rider ability in show jumping. Kinematic analysis and motion sensors have been used in sports other than show jumping to measure the quality of motor control patterns in humans. The aim of this study was to quantify rider ability in show jumping using body-mounted IMUs. Preliminary results indicate that there are clear differences in experienced and novice riders during show jumping.
Distance perception in the spiny mouse Acomys cahirinus: vertical jumping.
Goldman, M; Skolnick, A J; Hernandez, T P; Tobach, E
1992-12-01
Acomys cahirinus, a precocial muroid, that has shown precise jumping in the natural habitat, did not jump from 25 cm in a laboratory situation. To investigate this further, A. cahirinus were observed jumping from platforms at two different heights, onto different sized checkered substrates and from a visual cliff. Adult animals discriminated between platforms that were 6.4 cm and 25.4 cm above the substrate and between small and large checkered patterns on the floor. Most adult animals and neonates jumped down on the shallow side of the visual cliff. Animals developed individual patterns of jumping over a series of trials, with some jumping often, some rarely, and others jumping only from the low platform. Good distance perception was indicated when they did not jump from heights, and by their making appropriate postural adjustment when they did jump from heights and landed without mishap. Different spacing of trials indicated that height was a more effective stimulus for animals which had all four conditions on the same day, while floor pattern was more effective for animals with each of the four conditions on a separate day.
Long memory behavior of returns after intraday financial jumps
Behfar, Stefan Kambiz
2016-11-01
In this paper, characterization of intraday financial jumps and time dynamics of returns after jumps is investigated, and will be analytically and empirically shown that intraday jumps are power-law distributed with the exponent 1 finance, it is important to be able to distinguish between jumps and continuous sample path price movements, and this can be achieved by introducing a statistical test via calculating sums of products of returns over small period of time. In the case of having jump, the null hypothesis for normality test is rejected; this is based on the idea that returns are composed of mixture of normally-distributed and power-law distributed data (∼ 1 /r 1 + μ). Probability of rejection of null hypothesis is a function of μ, which is equal to one for 1 high returns after jumps are the effect; we show that returns caused by jump decay as power-law distribution. To test this idea empirically, we average over the time dynamics of all days; therefore the superposed time dynamics after jump represent a power-law, which indicates that there is a long memory with a power-law distribution of return after jump.
Biomechanics research in ski jumping, 1991-2006.
Schwameder, Hermann
2008-01-01
In this paper, I review biomechanics research in ski jumping with a specific focus on publications presented between 1991 and 2006 on performance enhancement, limiting factors of the take-off, specific training and conditioning, aerodynamics, and safety. The first section presents a brief description of ski jumping phases (in-run, take-off, early flight, stable flight, and landing) regarding the biomechanical and functional fundamentals. The most important and frequently used biomechanical methods in ski jumping (kinematics, ground reaction force analyses, muscle activation patterns, aerodynamics) are summarized in the second section. The third section focuses on ski jumping articles and research findings published after the establishment of the V-technique in 1991, as the introduction of this technique has had a major influence on performance enhancement, ski jumping regulations, and the construction of hill profiles. The final section proposes topics for future research in the biomechanics of ski jumping, including: take-off and early flight and the relative roles of vertical velocity and forward somersaulting angular momentum; optimal jumping patterns utilizing the capabilities of individual athletes; development of kinematic and kinetic feedback systems for hill jumps; comparisons of simulated and hill jumps; effect of equipment modifications on performance and safety enhancement.
Competitive Lotka-Volterra Population Dynamics with Jumps
Bao, Jianhai; Yin, Geroge; Yuan, Chenggui
2011-01-01
This paper considers competitive Lotka-Volterra population dynamics with jumps. The contributions of this paper are as follows. (a) We show stochastic differential equation (SDE) with jumps associated with the model has a unique global positive solution; (b) We discuss the uniform boundedness of $p$th moment with $p>0$ and reveal the sample Lyapunov exponents; (c) Using a variation-of-constants formula for a class of SDEs with jumps, we provide explicit solution for 1-dimensional competitive Lotka-Volterra population dynamics with jumps, and investigate the sample Lyapunov exponent for each component and the extinction of our $n$-dimensional model.
pH jump induced α-helix folding.
Directory of Open Access Journals (Sweden)
Donten M. L.
2013-03-01
Full Text Available pH can be used to impact the folding equilibrium of peptides and proteins. This fact is utilized, similarly to temperature jumps, in pH jump experiments employing laser time-resolved spectroscopy to study the function and structural dynamics of these molecules. Here the application of pH jumps in folding experiments was investigated. Experiments with poly-L-glutamic acid alpha-helix formation shown the critical aspects of pH jump experiments and yielded direct information about the folding kinetics monitored with the amide I IR band.
Effect of drop jump technique on the reactive strength index
Directory of Open Access Journals (Sweden)
Struzik Artur
2016-09-01
Full Text Available The basic drill of plyometric training aimed at improving lower limb power and jump height is a drop jump. This exercise can be performed using different techniques, which substantially affects jump variables. Therefore, the aim of this study was to compare the values of the reactive strength index (RSI for countermovement drop jumps (CDJs and bounce drop jumps (BDJs. The study was carried out in a group of 8 male youth basketball players. The tests were conducted using the AMTI BP600900 force plate to measure ground reaction forces and the Noraxon MyoMotion system to record kinematic data. Each player performed two CDJs and two BDJs from the height of 15, 30, 45 and 60 cm. The RSI was calculated as a ratio of jump height and contact time. Moreover, the RSI was determined for the amortization and take-off phases separately. Significant differences (p < 0.05 between RSI values for CDJs and BDJs were recorded for jumps from 30, 45 and 60 cm. Differences in RSI values for jumps from 15 cm were not significant. Furthermore, CDJ height values were significantly higher (p < 0.05 than the values recorded for BDJs. Times of contact, amortization and take-off during BDJs were significantly shorter (p < 0.05 than the respective values obtained for CDJs. Therefore, the use of the RSI to monitor plyometric training should be based on the drop jump technique that is commonly performed by basketball players.
Development of a Minimally Actuated Jumping-Rolling Robot
Directory of Open Access Journals (Sweden)
Thanhtam Ho
2015-04-01
Full Text Available This paper presents development of a hybrid mobile robot in order to take advantage of both rolling and jumping locomotion on the ground. According to the unique design of the mechanism, the robot is able to execute both jumping and rolling skilfully by using only one DC motor. Changing the centre of gravity enables rolling of the robot and storage of energy is utilized for jumping. Mechanism design and control logic are validated by computer simulation. Simulation results show that the robot can jump nearly 1.3 times its diameter and roll at the speed of 3.3 times its diameter per second.
Ramlan, Roszaidi; Brennan, Michael J.; Kovacic, Ivana; Mace, Brian R.; Burrow, Stephen G.
2016-08-01
This work concerns the application of certain non-linear phenomena - jump frequencies in a base-excited Duffing oscillator - to the estimation of the parameters of the system. First, approximate analytical expressions are derived for the relationships between the jump-up and jump-down frequencies, the damping ratio and the cubic stiffness coefficient. Then, experimental results, together with the results of numerical simulations, are presented to show how knowledge of these frequencies can be exploited.
Kweon, Jae Ryong
2016-09-01
In this paper, when the initial density has a jump across an interior curve in a bounded domain, we show unique existence, piecewise regularity and jump discontinuity dynamics for the density and the velocity vector governed by the Navier-Stokes equations of compressible viscous barotropic flows. A critical difficulty is in controlling the gradient of the pressure across the jump curve. This is resolved by constructing a vector function associated with the pressure jump value on the convecting curve and extending it to the whole domain.
Understanding the physics of bungee jumping
Heck, André; Uylings, Peter; Kędzierska, Ewa
2010-01-01
Changing mass phenomena like the motion of a falling chain, the behaviour of a falling elastic bar or spring, and the motion of a bungee jumper surprise many a physicist. In this article we discuss the first phase of bungee jumping, when the bungee jumper falls, but the bungee rope is still slack. In instructional material this phase is often considered a free fall, but when the mass of the bungee rope is taken into account, the bungee jumper reaches acceleration greater than g. This result is contrary to the usual experience with free falling objects and therefore hard to believe for many a person, even an experienced physicist. It is often a starting point for heated discussions about the quality of the experiments and the physics knowledge of the experimentalist, or it may even prompt complaints about the quality of current physics education. But experiments do reveal the truth and students can do them supported by information and communication technology (ICT) tools. We report on a research project done by secondary school students and use their work to discuss how measurements with sensors, video analysis of self-recorded high-speed video clips and computer modelling allow study of the physics of bungee jumping.
Jumping and Landing Techniques in Elite Women’s Volleyball
Tillman, Mark D.; Hass, Chris J.; Brunt, Denis; Bennett, Gregg R.
2004-01-01
Volleyball has become one of the most widely played participant sports in the world. Participation requires expertise in many physical skills and performance is often dependent on an individual’s ability to jump and land. The incidence of injury in volleyball is similar to the rates reported for sports that are considered more physical contact sports. Though the most common source of injury in volleyball is the jump landing sequence, little research exists regarding the prevalence of jumping and landing techniques. The purpose of this study was to quantify the number of jumps performed by female volleyball players in competitive matches and to determine the relative frequency of different jump-landing techniques. Videotape recordings of two matches among four volleyball teams were analyzed for this study. Each activity was categorized by jump type (offensive spike or defensive block) and phase (jump or landing). Phase was subcategorized by foot use patterns (right, left, or both). Each of the players averaged nearly 22 jump-landings per game. Foot use patterns occurred in unequal amounts (p < 0.001) with over 50% of defensive landings occurring on one foot. Coaches, physical educators, and recreation providers may utilize the findings of this inquiry to help prevent injuries in volleyball. Key Points The incidence of injury in volleyball is nearly equivalent to injury rates reported for ice hockey and soccer. Most injuries in volleyball occur during the jump landing sequence, but few data exist regarding jump landing techniques for elite female players. Our data indicate that the vast majority of jumps utilize two feet, but approximately half of landings occur with only one foot. Coaches, physical educators, and recreation providers may utilize the findings of this inquiry to prevent possible injuries in athletes, students, or those who participate in volleyball for recreational purposes. PMID:24497818
Neuromuscular function during drop jumps in young and elderly males.
Piirainen, Jarmo M; Linnamo, Vesa; Sippola, Niina; Avela, Janne
2012-12-01
The Hoffman reflex (H-reflex), indicating alpha-motoneuron pool activity, has been shown to be task - and in resting conditions - age dependent. How aging affects H-reflex activity during explosive movements is not clear at present. The purpose of this study was to examine the effects of aging on H-reflexes during drop jumps, and its possible role in drop jump performance. Ten young (26.8 ± 2.7 years) and twenty elderly (64.2 ± 2.7 years) subjects participated in the study. Maximal drop jump performance and soleus H-reflex response (H/M jump) 20 ms after ground contact were measured in a sledge ergometer. Maximal H-reflex, maximal M-wave, Hmax/Mmax-ratio and H-reflex excitability curves were measured during standing rest. Although in young the H-reflex response (Hmax/Mmax) was 6.5% higher during relaxed standing and 19.7% higher during drop jumps (H jump/M jump) than in the elderly group, these differences were not statistically significant. In drop jumps, the elderly subjects had lower jumping height (30.4%, p push-off force (18.0%, p push-off time (31.0% p push-off force (r = 0.833, p push-off time (r = -0.857, p strategies in drop jumps. However, it does not fully explain age related differences in jumping performance, since age related differences in H-reflex activity were non-significant. Copyright © 2012 Elsevier Ltd. All rights reserved.
Astley, H C; Abbott, E M; Azizi, E; Marsh, R L; Roberts, T J
2013-11-01
Maximal performance is an essential metric for understanding many aspects of an organism's biology, but it can be difficult to determine because a measured maximum may reflect only a peak level of effort, not a physiological limit. We used a unique opportunity provided by a frog jumping contest to evaluate the validity of existing laboratory estimates of maximum jumping performance in bullfrogs (Rana catesbeiana). We recorded video of 3124 bullfrog jumps over the course of the 4-day contest at the Calaveras County Jumping Frog Jubilee, and determined jump distance from these images and a calibration of the jump arena. Frogs were divided into two groups: 'rental' frogs collected by fair organizers and jumped by the general public, and frogs collected and jumped by experienced, 'professional' teams. A total of 58% of recorded jumps surpassed the maximum jump distance in the literature (1.295 m), and the longest jump was 2.2 m. Compared with rental frogs, professionally jumped frogs jumped farther, and the distribution of jump distances for this group was skewed towards long jumps. Calculated muscular work, historical records and the skewed distribution of jump distances all suggest that the longest jumps represent the true performance limit for this species. Using resampling, we estimated the probability of observing a given jump distance for various sample sizes, showing that large sample sizes are required to detect rare maximal jumps. These results show the importance of sample size, animal motivation and physiological conditions for accurate maximal performance estimates.
Modeling financial contagion using mutually exciting jump processes
Aït-Sahalia, Y.; Cacho-Diaz, J.; Laeven, R.J.A.
2013-01-01
We propose a model designed to capture the dynamics of asset returns, with periods of crises that are characterized by contagion. In the model, a jump in one region of the world increases the intensity of jumps both in the same region (self-excitation) as well as in other regions (mutual
Modeling financial contagion using mutually exciting jump processes
Aït-Sahalia, Y.; Cacho-Diaz, J.; Laeven, R.J.A.
2015-01-01
We propose a model to capture the dynamics of asset returns, with periods of crises that are characterized by contagion. In the model, a jump in one region of the world increases the intensity of jumps both in the same region (self-excitation) as well as in other regions (cross-excitation),
How Can We Tell if Frogs Jump Further?
Drummond, Gordon B.; Tom, Brian D. M.
2011-01-01
How effective is training frogs to jump? This is perhaps the most frequent question in biology that is subjected to statistical analysis: does a treatment make a difference? One can examine whether there is indeed a training effect, by first assuming the opposite. That is, the authors assume that training has no effect on the mean distance jumped.…
Teaching Jump Rope to Children with Visual Impairments
Lieberman, Lauren J.; Schedlin, Haley; Pierce, Tristan
2009-01-01
This article presents strategies for jumping rope for children with visual impairments. Giving choices related to the types of rope and the use of mats is important. In addition, using appropriate instructional strategies and modifications will make jumping rope a skill that the children will enjoy and will lead to their involvement in other…
Jump Tails, Extreme Dependencies, and the Distribution of Stock Returns
DEFF Research Database (Denmark)
Bollerslev, Tim; Todorov, Viktor
We provide a new framework for estimating the systematic and idiosyncratic jump tail risks in financial asset prices. The theory underlying our estimates are based on in-fill asymptotic arguments for directly identifying the systematic and idiosyncratic jumps, together with conventional long...
The Triple Jump: Assessing Problem Solving in Psychiatry.
O'Gorman, Ethna C.; Trimble, Peter; Smyth, Joe
1998-01-01
Describes an attempt to assess a final-year course in psychiatry using the Triple Jump. In this course, students on placement in psychiatric units perfect psychiatry skills that were acquired during the previous year by direct contact with patients. The Triple Jump is used to assess problem-solving skills in management strategy on cases. (PVD)
Feller Property for a Special Hybrid Jump-Diffusion Model
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Jinying Tong
2014-01-01
Full Text Available We consider the stochastic stability for a hybrid jump-diffusion model, where the switching here is a phase semi-Markovian process. We first transform the process into a corresponding jump-diffusion with Markovian switching by the supplementary variable technique. Then we prove the Feller and strong Feller properties of the model under some assumptions.
A time inhomogeneous Cox-Ingersoll-Ross diffusion with jumps
Hoepfner, Reinhard
2009-01-01
We consider a time inhomogeneous Cox-Ingersoll-Ross diffusion with positive jumps. We exploit a branching property to prove existence of a unique strong solution under a restrictive condition on the jump measure. We give Laplace transforms for the transition probabilities, with an interpretation in terms of limits of mixtures over Gamma laws.
How Can We Tell if Frogs Jump Further?
Drummond, Gordon B.; Tom, Brian D. M.
2011-01-01
How effective is training frogs to jump? This is perhaps the most frequent question in biology that is subjected to statistical analysis: does a treatment make a difference? One can examine whether there is indeed a training effect, by first assuming the opposite. That is, the authors assume that training has no effect on the mean distance jumped.…
Tuning Superhydrophobic Nanostructures to Enhance Jumping-Droplet Condensation
Mulroe, Megan; Srijanto, Bernadeta; Collier, Patrick; Boreyko, Jonathan
2016-11-01
It was recently discovered that condensation growing on a nanostructured superhydrophobic surface can spontaneously jump off the surface when two or more droplets coalesce together. The minimum droplet size for jumping to occur is of order 10 microns, but it is unclear whether this is the true lower limit of jumping droplets or simply a limitation of current superhydrophobic surfaces. Here, we analyze the dynamics of jumping droplets on six different superhydrophobic surfaces where the topography of the nanopillars was systematically varied. The critical diameter for jumping to occur was observed to be highly dependent upon the height and diameter of the nanopillars; surfaces with very tall and slender nanopillars enabled jumping droplets at a smaller critical size of order 1 micron. An energetic model of the incipient growth of condensate shows that the nanostructure topology affects the rate of increase of a growing droplet's apparent contact angle, with jumping being enabled at very large angles. These findings indicate that the true upper limit to the performance of jumping-droplet condensers has not yet been reached and can be further improved using advanced nanofabrication techniques.
Empirical likelihood inference for diffusion processes with jumps
Institute of Scientific and Technical Information of China (English)
无
2010-01-01
In this paper, we consider the empirical likelihood inference for the jump-diffusion model. We construct the confidence intervals based on the empirical likelihood for the infinitesimal moments in the jump-diffusion models. They are better than the confidence intervals which are based on the asymptotic normality of point estimates.
A Safe and Effective Modification of Thomson's Jumping Ring Experiment
Waschke, Felix; Strunz, Andreas; Meyn, Jan-Peter
2012-01-01
The electrical circuit of the jumping ring experiment based on discharging a capacitor is optimized. The setup is scoop proof at 46 V and yet the ring jumps more than 9 m high. The setup is suitable for both lectures and student laboratory work in higher education. (Contains 1 table, 8 figures and 3 footnotes.)
Could the deep squat jump predict weightlifting performance?
Vizcaya, Francisco J; Viana, Oscar; del Olmo, Miguel Fernandez; Acero, Rafael Martin
2009-05-01
This research was carried out with the aim of describing the deep squat jump (DSJ) and comparing it with the squat (SJ) and countermovement (CMJ) jumps, to introduce it as a strength testing tool in the monitoring and control of training in strength and power sports. Forty-eight male subjects (21 weightlifters, 12 triathletes, and 15 physical education students) performed 3 trials of DSJ, SJ, and CMJ with a 1-minute rest among them. For the weightlifters, snatch and clean and jerk results during the Spanish Championship 2004 and the 35th EU Championships 2007 were collected to study the relationship among vertical jumps and weightlifters' performance. A 1-way analysis of variance (ANOVA) showed significant differences between groups in the vertical jumps, with the highest jumps for the weightlifters and the lowest for the triathletes. An ANOVA for repeated measures (type of jump) showed better results for DSJ and CMJ than SJ in all groups. A linear regression analysis was performed to determine the association between weightlifting and vertical jump performances. Correlations among the weightlifting performance and the vertical jumps were also calculated and determined using Pearson r. Results have shown that both CMJ and DSJ are strongly correlated with weightlifting ability. Therefore, both measures can be useful for coaches as a strength testing tool in the monitoring and control of training in weightlifting.
Evaluation of Metabolic Stress between Jumping at Different Cadences on the Digi-Jump Machine.
Lyons, Thomas S; Navalta, James W; Callahan, Zachary J
The American College of Sports Medicine (ACSM) recommends that healthy adults achieve a minimum of thirty minutes of moderate intensity aerobic exercise five days per week. While cycling, walking, and jogging are commonly observed methods of achieving these recommendations, another option may be repetitive jumping. The purpose of this study was to examine the metabolic responses between repetitive jumping at a cadence of 120 jumps per minute (JPMs) vs. 100 JPMs when utilizing the Digi-Jump machine. Twenty-eight subjects completed two jumping trials, one at 120 JPMs and one at 100 JPMs. Subjects jumped until volitional exhaustion, or for a maximum of fifteen minutes. Oxygen uptake (VO2), heart rate (HR), respiratory exchange ratio (RER), and rating of perceived exertion (RPE) were assessed each minute of each exercise trial. RPE was differentiated, in that subjects reported perceived exertion of their total body, their upper-leg, and their lower leg. Results of this study indicated that there was no significant difference between the two trials for VO2, HR, or total body RPE. Differences were reported between trials for peak and average RER, with the 120 JPM trial eliciting a lower RER for both (peak: 1.08 ± .087 vs. 1.17 ± .1 p=.000; average: .99 ± .076 vs. 1.04 ± .098 p=.002), peak upper leg RPE (120: 15.29 ± 3.89 vs. 100: 16.75 ± 2.52 p=.022), and average lower leg RPE (120: 15.04 ± 2.55 vs. 100: 13.94 ± 2.02 p=.019). Also, there was a significant difference in exercise duration between the trials, with subjects able to exercise longer during the 120 JPM trial (12.4 ± 3.42 mins vs. 9.68 ± 4.31 mins p=.000). These data indicate that while the physiological stress may not be different between the two trials as indicated by VO2 and HR, the 120 JPM trial appears less strenuous as evidenced by RER values and by subjects' ability to exercise longer at that cadence.
The hydraulic jump and ripples in liquid helium
Energy Technology Data Exchange (ETDEWEB)
Rolley, E. [Laboratoire de Physique Statistique de l' ENS, associe au CNRS et aux Universites Paris 6 et Paris 7, 24 rue Lhomond, 75005 Paris (France)]. E-mail: rolley@lps.ens.fr; Guthmann, C. [Laboratoire de Physique Statistique de l' ENS, associe au CNRS et aux Universites Paris 6 et Paris 7, 24 rue Lhomond, 75005 Paris (France); Pettersen, M.S. [Washington and Jefferson College, 60 S. Lincoln St., Washington, PA 15301 (United States)
2007-05-01
We have studied the characteristics of the circular hydraulic jump using liquid helium. Surprisingly, the radius of the jump does not change at the superfluid transition. We think that the flow is still dissipative below the lambda point because the velocity exceeds the critical one. The jump radius R{sub j} is compared with various models. In our parameter range, we find that the jump can be treated as a shock, and that capillary effects are important. Below the superfluid transition, we observed a standing capillary wave between the impact of the jet and the jump. Assuming that the superfluid flow can be described with an effective viscosity, we calculate the wave vector and thus obtain the value of the liquid thickness, which is in reasonable agreement with predictions. However, the spatial variation of the wave amplitude depends much more strongly on temperature than we calculate.
Effects of isometric scaling on vertical jumping performance.
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Maarten F Bobbert
Full Text Available Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli's law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations.
Effects of isometric scaling on vertical jumping performance.
Bobbert, Maarten F
2013-01-01
Jump height, defined as vertical displacement in the airborne phase, depends on vertical takeoff velocity. For centuries, researchers have speculated on how jump height is affected by body size and many have adhered to what has come to be known as Borelli's law, which states that jump height does not depend on body size per se. The underlying assumption is that the amount of work produced per kg body mass during the push-off is independent of size. However, if a big body is isometrically downscaled to a small body, the latter requires higher joint angular velocities to achieve a given takeoff velocity and work production will be more impaired by the force-velocity relationship of muscle. In the present study, the effects of pure isometric scaling on vertical jumping performance were investigated using a biologically realistic model of the human musculoskeletal system. The input of the model, muscle stimulation over time, was optimized using jump height as criterion. It was found that when the human model was miniaturized to the size of a mouse lemur, with a mass of about one-thousandth that of a human, jump height dropped from 40 cm to only 6 cm, mainly because of the force-velocity relationship. In reality, mouse lemurs achieve jump heights of about 33 cm. By implication, the unfavourable effects of the small body size of mouse lemurs on jumping performance must be counteracted by favourable effects of morphological and physiological adaptations. The same holds true for other small jumping animals. The simulations for the first time expose and explain the sheer magnitude of the isolated effects of isometric downscaling on jumping performance, to be counteracted by morphological and physiological adaptations.
Dynamics and stability of directional jumps in the desert locust
Gvirsman, Omer
2016-01-01
Locusts are known for their ability to jump large distances to avoid predation. The jump also serves to launch the adult locust into the air in order to initiate flight. Various aspects of this important behavior have been studied extensively, from muscle physiology and biomechanics, to the energy storage systems involved in powering the jump, and more. Less well understood are the mechanisms participating in control of the jump trajectory. Here we utilise video monitoring and careful analysis of experimental directional jumps by adult desert locusts, together with dynamic computer simulation, in order to understand how the locusts control the direction and elevation of the jump, the residual angular velocities resulting from the jump and the timing of flapping-flight initiation. Our study confirms and expands early findings regarding the instrumental role of the initial body position and orientation. Both real-jump video analysis and simulations based on our expanded dynamical model demonstrate that the initial body coordinates of position (relative to the hind-legs ground-contact points) are dominant in predicting the jumps’ azimuth and elevation angles. We also report a strong linear correlation between the jumps’ pitch-angular-velocity and flight initiation timing, such that head downwards rotations lead to earlier wing opening. In addition to offering important insights into the bio-mechanical principles of locust jumping and flight initiation, the findings from this study will be used in designing future prototypes of a bio-inspired miniature jumping robot that will be employed in animal behaviour studies and environmental monitoring applications. PMID:27703846
Dynamics and stability of directional jumps in the desert locust
Directory of Open Access Journals (Sweden)
Omer Gvirsman
2016-09-01
Full Text Available Locusts are known for their ability to jump large distances to avoid predation. The jump also serves to launch the adult locust into the air in order to initiate flight. Various aspects of this important behavior have been studied extensively, from muscle physiology and biomechanics, to the energy storage systems involved in powering the jump, and more. Less well understood are the mechanisms participating in control of the jump trajectory. Here we utilise video monitoring and careful analysis of experimental directional jumps by adult desert locusts, together with dynamic computer simulation, in order to understand how the locusts control the direction and elevation of the jump, the residual angular velocities resulting from the jump and the timing of flapping-flight initiation. Our study confirms and expands early findings regarding the instrumental role of the initial body position and orientation. Both real-jump video analysis and simulations based on our expanded dynamical model demonstrate that the initial body coordinates of position (relative to the hind-legs ground-contact points are dominant in predicting the jumps’ azimuth and elevation angles. We also report a strong linear correlation between the jumps’ pitch-angular-velocity and flight initiation timing, such that head downwards rotations lead to earlier wing opening. In addition to offering important insights into the bio-mechanical principles of locust jumping and flight initiation, the findings from this study will be used in designing future prototypes of a bio-inspired miniature jumping robot that will be employed in animal behaviour studies and environmental monitoring applications.
Jumping Jupiter can explain Mercury's orbit
Roig, Fernando; DeSouza, Sandro Ricardo
2016-01-01
The orbit of Mercury has large values of eccentricity and inclination that cannot be easily explained if this planet formed on a circular and coplanar orbit. Here, we study the evolution of Mercury's orbit during the instability related to the migration of the giant planets in the framework of the jumping Jupiter model. We found that some instability models are able to produce the correct values of Mercury's eccentricity and inclination, provided that relativistic effects are included in the precession of Mercury's perihelion. The orbital excitation is driven by the fast change of the normal oscillation modes of the system corresponding to the perihelion precession of Jupiter (for the eccentricity), and the nodal regression of Uranus (for the inclination).
The Voter Model and Jump Diffusion
Majmudar, Jimit; Baumgaertner, Bert O; Tyson, Rebecca C
2015-01-01
Opinions, and subsequently opinion dynamics, depend not just on interactions among individuals, but also on external influences such as the mass media. The dependence on local interactions, however, has received considerably more attention. In this paper, we use the classical voter model as a basis, and extend it to include external influences. We show that this new model can be understood using the theory of jump diffusion processes. We derive results pertaining to fixation probability and expected consensus time of the process, and find that the contribution of an external influence significantly dwarfs the contribution of the node-to-node interactions in terms of driving the social network to eventual consensus. This result suggests the potential importance of ``macro-level'' phenomena such as the media influence as compared to the ``micro-level'' local interactions, in modelling opinion dynamics.
CAPTURE OF TROJANS BY JUMPING JUPITER
Energy Technology Data Exchange (ETDEWEB)
Nesvorny, David [Department of Space Studies, Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302 (United States); Vokrouhlicky, David [Institute of Astronomy, Charles University, V Holesovickach 2, 180 00 Prague 8 (Czech Republic); Morbidelli, Alessandro [Departement Cassiopee, University of Nice, CNRS, Observatoire de la Cote d' Azur, Nice, F-06304 (France)
2013-05-01
Jupiter Trojans are thought to be survivors of a much larger population of planetesimals that existed in the planetary region when planets formed. They can provide important constraints on the mass and properties of the planetesimal disk, and its dispersal during planet migration. Here, we tested a possibility that the Trojans were captured during the early dynamical instability among the outer planets (aka the Nice model), when the semimajor axis of Jupiter was changing as a result of scattering encounters with an ice giant. The capture occurs in this model when Jupiter's orbit and its Lagrange points become radially displaced in a scattering event and fall into a region populated by planetesimals (that previously evolved from their natal transplanetary disk to {approx}5 AU during the instability). Our numerical simulations of the new capture model, hereafter jump capture, satisfactorily reproduce the orbital distribution of the Trojans and their total mass. The jump capture is potentially capable of explaining the observed asymmetry in the number of leading and trailing Trojans. We find that the capture probability is (6-8) Multiplication-Sign 10{sup -7} for each particle in the original transplanetary disk, implying that the disk contained (3-4) Multiplication-Sign 10{sup 7} planetesimals with absolute magnitude H < 9 (corresponding to diameter D = 80 km for a 7% albedo). The disk mass inferred from this work, M{sub disk} {approx} 14-28 M{sub Earth}, is consistent with the mass deduced from recent dynamical simulations of the planetary instability.
Hydraulic jumps within pyroclastic density currents and their sedimentary record
Douillet, G.; Mueller, S.; Kueppers, U.; Dingwell, D. B.
2013-12-01
This contribution presents a complete and comprehensive formulation of the hydraulic jump phenomenon and reviews sedimentary structures that may be associated with them. Beginning from the general fluid phenomenon, we then focus on examples from pyroclastic density currents in order to infer dynamic parameters on the parent flows. A hydraulic jump is a fluid dynamics phenomenon that corresponds to the sudden increase of the thickness of a flow accompanied by a decrease of its velocity and/or density. A hydraulic jump is the expression of the transition of the flow from two different flow regimes: supercritical to subcritical. This entrains a change in the energy balance between kinetic energy and gravity potential energy. Recently, the terms of 'pneumatic jumps' have been used for similar phenomenon driven within a gas phase, and granular jumps for dense granular flows. It is thought that such strong changes in the flow conditions may leave characteristic structures in the sedimentary record. Indeed, the main variables influencing the sedimentation rate are the flow velocity, particle concentration and turbulence level, all of them strongly affected by a hydraulic jump. Structures deposited by hydraulic/pneumatic jumps have been called cyclic steps and chute and pool structures. Chute and pools represent the record of a single supercritical to subcritical transition, whereas cyclic steps are produced by stable trains of hydraulic jumps and subsequent re-accelerations. Pyroclastic density currents (PDCs) are gas and pyroclasts flows. As such, they can be subjected to granular and pneumatic jumps and their deposit have often been interpreted as containing records of jumps. Steep sided truncations covered by lensoidal layers have been interpreted as the record of internal jumps within density stratified flows. Fines-depleted breccias at breaks in slope are thought to result from the enhanced turbulence at a jump of the entire flow. Sudden increases in thickness of
A COMPARISON OF PAIRS FIGURE SKATERS IN REPEATED JUMPS
Directory of Open Access Journals (Sweden)
William A. Sands
2012-03-01
Full Text Available Trends in pairs figure skating have shown that increasingly difficult jumps have become an essential aspect of high-level performance, especially in the latter part of a competitive program. We compared a repeated jump power index in a 60 s repeated jump test to determine the relationship of repeated jump test to competitive rank and to measure 2D hip, knee, and ankle angles and angular velocities at 0, 20, 40, and 60 s. Eighteen National Team Pairs Figure Skaters performed a 60 s repeated jump test on a large switch-mat with timing of flight and ground durations and digital video recording. Each 60-s period was divided into 6, 10-s intervals, with power indexes (W/kg calculated for each 10-s interval. Power index by 10-s interval repeated measures ANOVAs (RMANOVA showed that males exceeded females at all intervals, and the highest power index interval was during 10 to 20 s for both sexes. RMANOVAs of angles and angular velocities showed main effects for time only. Power index and jumping techniques among figure skaters showed rapid and steady declines over the test duration. Power index can predict approximately 50% of competitive rank variance, and sex differences in jumping technique were rare
Effects of Foam Rolling on Vertical Jump Performance
Directory of Open Access Journals (Sweden)
Andrew Jones
2015-07-01
Full Text Available Background: Foam rolling is a popular activity utilized by strength and conditioning coaches as it is believed to increase muscle length and break up fibrous adhesions located in connective tissue. However, there is little research investigating the effects of foam rolling on athletic performance. Objective: The purpose of this study was to investigate the effects of lower body foam rolling on vertical jump performance. Methods: Twenty males (age 24.05 ± 2.02 years; height 177.43 ± 6.31 cm; mass 81.41 ± 8.76 kg volunteered to participate. Subjects completed three days of testing, separated by at least twenty-four hours. Day one consisted of baseline vertical jumps on a force plate, followed by familiarization with foam rolling and control protocols. Subjects returned on days two and three and performed 30-second bouts of lower body foam rolling or mimicked foam rolling movements on a skateboard followed by vertical jumps on a force plate. The highest jump from each day was used for statistical analyses. Results: Repeated measures ANOVAs revealed no significant differences in Jump height, impulse, relative ground reaction force, or take-off velocity between conditions. Conclusion: 30-second bouts of lower body foam rolling do not improve vertical jump performance. Keywords: Dynamic Warm-Up, Foam Rolling, Vertical Jump
Condensed droplet jumping: Capillary to inertial energy transfer
Enright, Ryan; Miljkovic, Nenad; Morris, Michael; Wang, Evelyn
2013-03-01
When condensed droplets coalesce on a superhydrophobic nanostructured surface, the resulting droplet can jump from the surface due to the release of excess surface energy. This behavior has been shown to follow a simple inertial-capillary scaling. However, questions remain regarding the nature of the energy conversion process linking the excess surface energy of the system before coalescence and the kinetic energy of the jumping droplet. Furthermore, the primary energy dissipation mechanisms limiting this jumping behavior remain relatively unexplored. In this work, we present new experimental data from a two-camera setup capturing the trajectory of jumping droplets on nanostructured surfaces with a characteristic surface roughness length scale on the order of 10 nm. Coupled with a model developed to capture the main details of the bridging flow during coalescence, our findings suggest that: 1. the excess surface energy available for jumping is a fraction of that suggested by simple scaling due to incomplete energy transfer, 2. internal viscous dissipation is not a limiting factor on the jumping process at droplet sizes on the order of 10 μm and 3. jumping performance is strongly affected by forces associated with the external flow and fields around the droplet. This work suggests bounds on the heat transfer performance of superhydrophobic condensation surfaces.
Aerial jumping in the Trinidadian guppy (Poecilia reticulata).
Soares, Daphne; Bierman, Hilary S
2013-01-01
Many fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above. The fish jump spontaneously, without being triggered by overt sensory cues, is not migratory and does not attempt to capture aerial food items. Here, we use high speed video imaging to analyze the kinematics of the jumping behavior P. reticulata. Fish jump from a still position by slowly backing up while using its pectoral fins, followed by strong body trusts which lead to launching into the air several body lengths. The liftoff phase of the jump is fast and fish will continue with whole body thrusts and tail beats, even when out of the water. This behavior occurs when fish are in a group or in isolation. Geography has had substantial effects on guppy evolution, with waterfalls reducing gene flow and constraining dispersal. We suggest that jumping has evolved in guppies as a behavioral phenotype for dispersal.
Aerial jumping in the Trinidadian guppy (Poecilia reticulata.
Directory of Open Access Journals (Sweden)
Daphne Soares
Full Text Available Many fishes are able to jump out of the water and launch themselves into the air. Such behavior has been connected with prey capture, migration and predator avoidance. We found that jumping behavior of the guppy Poecilia reticulata is not associated with any of the above. The fish jump spontaneously, without being triggered by overt sensory cues, is not migratory and does not attempt to capture aerial food items. Here, we use high speed video imaging to analyze the kinematics of the jumping behavior P. reticulata. Fish jump from a still position by slowly backing up while using its pectoral fins, followed by strong body trusts which lead to launching into the air several body lengths. The liftoff phase of the jump is fast and fish will continue with whole body thrusts and tail beats, even when out of the water. This behavior occurs when fish are in a group or in isolation. Geography has had substantial effects on guppy evolution, with waterfalls reducing gene flow and constraining dispersal. We suggest that jumping has evolved in guppies as a behavioral phenotype for dispersal.
Optimizing the Distribution of Leg Muscles for Vertical Jumping.
Wong, Jeremy D; Bobbert, Maarten F; van Soest, Arthur J; Gribble, Paul L; Kistemaker, Dinant A
2016-01-01
A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas-which determine the maximum force deliverable by the muscles-constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of the skeletal
Optimizing the Distribution of Leg Muscles for Vertical Jumping.
Directory of Open Access Journals (Sweden)
Jeremy D Wong
Full Text Available A goal of biomechanics and motor control is to understand the design of the human musculoskeletal system. Here we investigated human functional morphology by making predictions about the muscle volume distribution that is optimal for a specific motor task. We examined a well-studied and relatively simple human movement, vertical jumping. We investigated how high a human could jump if muscle volume were optimized for jumping, and determined how the optimal parameters improve performance. We used a four-link inverted pendulum model of human vertical jumping actuated by Hill-type muscles, that well-approximates skilled human performance. We optimized muscle volume by allowing the cross-sectional area and muscle fiber optimum length to be changed for each muscle, while maintaining constant total muscle volume. We observed, perhaps surprisingly, that the reference model, based on human anthropometric data, is relatively good for vertical jumping; it achieves 90% of the jump height predicted by a model with muscles designed specifically for jumping. Alteration of cross-sectional areas-which determine the maximum force deliverable by the muscles-constitutes the majority of improvement to jump height. The optimal distribution results in large vastus, gastrocnemius and hamstrings muscles that deliver more work, while producing a kinematic pattern essentially identical to the reference model. Work output is increased by removing muscle from rectus femoris, which cannot do work on the skeleton given its moment arm at the hip and the joint excursions during push-off. The gluteus composes a disproportionate amount of muscle volume and jump height is improved by moving it to other muscles. This approach represents a way to test hypotheses about optimal human functional morphology. Future studies may extend this approach to address other morphological questions in ethological tasks such as locomotion, and feature other sets of parameters such as properties of
Jumping numbers and ordered tree structures on the dual graph
Hyry, Eero
2010-01-01
Let R be a two-dimensional regular local ring having an algebraically closed residue field and let a be a complete ideal of finite colength in R. In this article we investigate the jumping numbers of a by means of the dual graph of the minimal log resolution of the pair (X,a). Our main result is a combinatorial criterium for a positive rational number to be a jumping number. In particular, we associate to each jumping number certain ordered tree structures on the dual graph.
Nonstandard analysis and jump conditions for converging shock waves
Baty, Roy S.; Farassat, F.; Tucker, Don H.
2008-06-01
Nonstandard analysis is an area of modern mathematics that studies abstract number systems containing both infinitesimal and infinite numbers. This article applies nonstandard analysis to derive jump conditions for one-dimensional, converging shock waves in a compressible, inviscid, perfect gas. It is assumed that the shock thickness occurs on an infinitesimal interval and the jump functions in the thermodynamic and fluid dynamic parameters occur smoothly across this interval. Predistributions of the Heaviside function and the Dirac delta measure are introduced to model the flow parameters across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the flow parameters.
[Autogenic training in psychophysiological preparation for parachute jumps].
Reshetnikov, M M
1978-01-01
The efficiency of specific psychophysiological preparation--autogenic training--to parachute jumps was measured in two groups of cadets (test subjects and controls). Hetero- and autogenic training was carried out according to a scheme specially developed for this type of activity. The study of questionnaires and physiological data demonstrated that the specific psychophysiological preparation by means of autogenic training for a certain type of activity helped to develop active self-control over one's own state and emotions, alleviated tension, arrested adverse neurotic manifestations (sleep disturbances, depression, anxiety), contributed to the feeling of confidence in the successful completion of the jump and promoted positive tuning towards subsequent jumps.
Stochastic mutualism model with Lévy jumps
Liu, Qun; Jiang, Daqing; Shi, Ningzhong; Hayat, Tasawar; Alsaedi, Ahmed
2017-02-01
In this paper, we consider a stochastic mutualism model with Lévy jumps. First of all, we show that the positive solution of the system is stochastically ultimate bounded. Then under a simple assumption, we establish sufficient and necessary conditions for the stochastic permanence and extinction of the system. The results show an important property of the Lévy jumps: they are unfavorable for the permanence of the species. Moreover, when there are no Lévy jumps, we show that there is a unique ergodic stationary distribution of the corresponding system under certain conditions. Some numerical simulations are introduced to validate the theoretical results.
RESEARCH ON JUMPING SEQUENCE PLANNING ISSUES OF HOPPING ROBOTS
Institute of Scientific and Technical Information of China (English)
LIUZhuang-zhi; ZHUJian-ying
2004-01-01
The wheeled or crawled robots often suffer from big obstacles or ditches, so a hopping robot needs to fit the tough landform in the field environments. In order to jump over obstacles rapidly, a jumping sequence must be generated based on the landform information from sensors or user input. The planning method for planar mobile robots is compared with that of hopping robots. Several factors can change the planning result. Adjusting these coefficients, a heuristic searching algorithm for the jumping sequence is developed on a simplified landform. Calculational result indicates that the algorithm can achieve safety and efficient control sequences for a desired goal.
Jump-Down Performance Alterations after Space Flight
Reschke, M. F.; Kofman, I. S.; Cerisano, J. M.; Fisher, E. A.; Peters, B. T.; Miller, C. A.; Harm, D. L.; Bloomberg, J. J.
2011-01-01
INTRODUCTION: Successful jump performance requires functional coordination of visual, vestibular, and somatosensory systems, which are affected by prolonged exposure to microgravity. Astronauts returning from space flight exhibit impaired ability to coordinate effective landing strategies when jumping from a platform to the ground. This study compares jump strategies used by astronauts before and after flight, changes to those strategies within a test session, and recoveries in jump-down performance parameters across several postflight test sessions. These data were obtained as part of an ongoing interdisciplinary study (Functional Task Test, FTT) designed to evaluate both astronaut postflight functional performance and related physiological changes. METHODS: Seven astronauts from short-duration (Shuttle) and three from long-duration (International Space Station) flights performed 3 two-footed jumps from a platform 30 cm high onto a force plate that measured the ground reaction forces and center-of-pressure displacement from the landings. Neuromuscular activation data were collected from the medial gastrocnemius and anterior tibialis of both legs using surface electromyography electrodes. Two load cells in the platform measured the load exerted by each foot during the takeoff phase of the jump. Data were collected in 2 preflight sessions, on landing day (Shuttle only), and 1, 6, and 30 days after flight. RESULTS: Postural settling time was significantly increased on the first postflight test session and many of the astronauts tested were unable to maintain balance on their first jump landing but recovered by the third jump, showing a learning progression in which performance improvements could be attributed to adjustments in takeoff or landing strategy. Jump strategy changes were evident in reduced air time (time between takeoff and landing) and also in increased asymmetry in foot latencies on takeoff. CONCLUSIONS: The test results revealed significant decrements
Detection of weak frequency jumps for GNSS onboard clocks.
Huang, Xinming; Gong, Hang; Ou, Gang
2014-05-01
In this paper, a weak frequency jump detection method is developed for onboard clocks in global navigation satellite systems (GNSS). A Kalman filter is employed to facilitate the onboard real-time processing of atomic clock measurements, whose N-step prediction residuals are used to construct the weak frequency jump detector. Numerical simulations show that the method can successfully detect weak frequency jumps. The detection method proposed in this paper is helpful for autonomous integrity monitoring of GNSS satellite clocks, and can also be applied to other frequency anomalies with an appropriately modified detector.
Jump diffusion models and the evolution of financial prices
Figueiredo, Annibal; de Castro, Marcio T.; da Silva, Sergio; Gleria, Iram
2011-08-01
We analyze a stochastic model to describe the evolution of financial prices. We consider the stochastic term as a sum of the Wiener noise and a jump process. We point to the effects of the jumps on the return time evolution, a central concern of the econophysics literature. The presence of jumps suggests that the process can be described by an infinitely divisible characteristic function belonging to the De Finetti class. We then extend the De Finetti functions to a generalized nonlinear model and show the model to be capable of explaining return behavior.
Influence of stretching on warm up in jump and speed
Gálvez Ruiz, Pablo; Tapia Flores, A; Jurado Lavanant, A
2013-01-01
El objetivo del estudio es determinar si la realización de estiramientos pasivos, incluidos como parte del calentamiento, influyen en el rendimiento de la fuerza explosiva, en este caso en varios tests de salto vertical: Squat Jump (SJ), Countermouvement Jump (CMJ) y Reactive Jump (RJ); y también en un test de velocidad de 30 metros (mts.) con salida lanzada de 5 mts. Para ello, 9 jugadores del Málaga Club de Fútbol de categoría juvenil (18,22 ± 0,441 años) realizaron 2 protocolos de...
Asymptotic Distribution of the Jump Change-Point Estimator
Institute of Scientific and Technical Information of China (English)
Changchun TAN; Huifang NIU; Baiqi MIAO
2012-01-01
The asymptotic distribution of the change-point estimator in a jump changepoint model is considered.For the jump change-point model Xi =a + θI{[nTo] ＜ i ≤n} + εi,where εi (i =1,…,n) are independent identically distributed random variables with Eεi=0 and Var(εi) ＜ oo,with the help of the slip window method,the asymptotic distribution of the jump change-point estimator (T) is studied under the condition of the local alternative hypothesis.
Quantum jumps induced by matter-wave fluctuations
Torres, J M; Zippilli, S; Morigi, G
2010-01-01
We theoretically study the occurrence of quantum jumps in the resonance fluorescence of a trapped atom. Here, the atom is laser cooled in a configuration of level such that the occurrence of a quantum jump is associated to a change of the vibrational center-of-mass motion by one phonon. The statistics of the occurrence of the dark fluorescence period is studied as a function of the physical parameters and the corresponding features in the spectrum of resonance fluorescence are identified. We discuss the information which can be extracted on the atomic motion from the observation of a quantum jump in the considered setup.
Rate Theory for Correlated Processes: Double Jumps in Adatom Diffusion
DEFF Research Database (Denmark)
Jacobsen, J.; Jacobsen, Karsten Wedel; Sethna, J.
1997-01-01
We study the rate of activated motion over multiple barriers, in particular the correlated double jump of an adatom diffusing on a missing-row reconstructed platinum (110) surface. We develop a transition path theory, showing that the activation energy is given by the minimum-energy trajectory...... which succeeds in the double jump. We explicitly calculate this trajectory within an effective-medium molecular dynamics simulation. A cusp in the acceptance region leads to a root T prefactor for the activated rate of double jumps. Theory and numerical results agree....
Palmer, Emily; Deshler, Nicolas; Gorman, David; Neves, Catarina; Mittal, Rajat
2015-11-01
Flapping, gliding, running, crawling and swimming have all been studied extensively in the past and have served as a source of inspiration for engineering designs. In the current project, we explore a mode of locomotion that straddles ground and air: jumping. The subject of our study is among the most proficient of long-jumpers in Nature: the spider cricket of the family Rhaphidophoridae, which can jump more than 60 times its body length. Despite jumping this immense distance, these crickets usually land on their feet, indicating an ability to control their posture during ``flight.'' We employ high-speed videogrammetry, to examine the jumps and to track the crickets' posture and appendage orientation throughout their jumps. Simple aerodynamic models are developed to predict the aerodynamic forces and moment on the crickets during `flight`. The analysis shows that these wingless insects employ carefully controlled and coordinated positioning of the limbs during flight so as to increase jump distance and to stabilize body posture during flight. The principles distilled from this study could serve as an inspiration for small jumping robots that can traverse complex terrains.
Directory of Open Access Journals (Sweden)
Ferran Antoni Rodriguez
2013-01-01
Full Text Available Gymnastics floor exercises are composed of a set of four to five successive acrobatic jumps usually called a �series�. The aims of the study were: 1 to relate the acrobatic gymnastics performance of these series with a repeated jumps test of similar duration (R60, 2 to study the relation between R60 and physiological parameters (heart rate and blood lactate, and the performance obtained in different kinds of jumps, 3 to confirm whether R60, executed without a damped jumping technique, can be considered an anaerobic lactic power test. Twenty male and twenty-four female gymnasts performed three repeated jumps tests for 5 s (R5, 10 s (R10 and 60 s (R60 and vertical jumps, such as drop jumps (DJ, squat jumps (SJ and countermovement jumps (CMJ. We assessed heart rate (HR and blood lactate during R10 and R60. The average values of the maximal blood lactate concentration (Lmax after R10 (males = 2.5±0.6 mmol.l-1; females = 2.1±0.8 mmol.l-1 confirm that anaerobic glycolysis is not activated to a high level. In R60, the Lmax (males = 7.5±1.7 mmol.l-1; females = 5.9±2.1 mmol.l-1 that was recorded does not validate R60 as an anaerobic lactic power test. We confirmed the relation between the average power obtained in R60 (R60Wm and the acrobatic performance on the floor. The inclusion in the multiple regression equation of the best power in DJ and the best flight-contact ratio (FC in R5 confirms the influence of other non-metabolic components on the variability in R60 performance, at least in gymnasts.
Rensing, N; Westermann, A; Möller, D; von Piekartz, H
2015-12-01
Studies have shown changes in the technical and physical demands in modern handball. The game has increased considerably in speed, power and dynamics. Jump training has, therefore, become ever more important in the training of the athletes. These developments contribute to the fact that handball is now one of the most injury-prone types of sport, with the lower extremities being most frequently affected. Reactive jump training is not only used in training by now, but also increasingly in injury prevention. The aim of this study was to investigate the effectiveness of reactive jump training with handball players. 21 regional league handball players were randomly divided into an intervention group (n = 12) and a control group (n = 9). The intervention group completed a six-week reactive jump training programme while the control group went through a non-specific training programme. Jump height (squat and counter movement jump), isokinetic and isometric maximum power as well as muscle activity served as measuring parameters. A comparison of the intervention and control groups revealed that the reactive jump training led to significant improvements in jump height. The isometric and isokinetic maximum power measurements and the electromyographic activities of the triceps surae muscle demonstrated an improvement in the values within the intervention group. However, this improvement was not significant compared with the control group. Likewise both jumps correlated with the muscle activity of the soleus muscle as shown by electromyography. A moderate correlation was noticed between the isokinetic maximum power measurement and the electromyographic activity of the soleus and gastrocnemius medialis muscles. Furthermore, the correlations of the isometric and isokinetic maximum power meas-urements resulted in a strong correlation coefficient. This study revealed a significant increase in jump height after reactive jump training. There was no significant difference in
Testability Synthesis for Jumping Carry Adders
Directory of Open Access Journals (Sweden)
Chien-In Henry Chen
2002-01-01
Full Text Available Synthesis for testability ensures that the synthesized circuit is testable by exploring the fundamental relationship between don't care and redundancy. With the exploration of the relationship, redundancy removal can be applied to improve the testability, reduce the area and improve the speed of a synthesized circuit. The test generation problems have been adequately solved, therefore an innovative testability synthesis strategy is necessary for achieving the maximum fault coverage and area reduction for maximum speed. This paper presents a testability synthesis methodology applicable to a top–down design method based on the identification and removal of redundant faults. Emphasis has been placed on the testability synthesis of a high-speed binary jumping carry adder. A synthesized 32-bit testable adder implemented by a 1.2 μm CMOS technology performs addition in 4.09 ns. Comparing with the original synthesized circuit, redundancy removal yields a 100% testable design with a 15% improvement in speed and a 25% reduction in area.
Vortex jump behavior in coupled nanomagnetic heterostructures
Energy Technology Data Exchange (ETDEWEB)
Zhang, S.; Phatak, C., E-mail: cd@anl.gov [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States); Petford-Long, A. K. [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208 (United States); Heinonen, O. [Materials Science Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States); Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Rd, Evanston, Illinois 60208-3112 (United States)
2014-11-24
The spin configuration and magnetic behavior in patterned nanostructures can be controlled by manipulating the interplay between the competing energy terms. This in turn requires fundamental knowledge of the magnetic interactions at the local nanometer scale. Here, we report on the spin structure and magnetization behavior of patterned discs containing exchange coupled ferromagnetic layers with additional exchange bias to an antiferromagnetic layer. The magnetization reversal was explored by direct local visualization of the domain behavior using in-situ Lorentz transmission electron microscopy, from which quantitative magnetic induction maps were reconstructed. The roles of the main competing energy terms were elucidated and the reversal mechanism was identified as a coupled phenomenon of incoherent rotation in the exchange-biased layer and localized vortex nucleation and discontinuous propagation in the free layer, including an anomalous jump in the trajectory. The observations were supported by micromagnetic simulations and modeled phase shift simulations. The work presented here provides fundamental insights into opportunities for macroscopic control of the energy landscape of magnetic heterostructures for functional applications.
Ethics in radiology: wait lists queue jumping.
Cunningham, Natalie; Reid, Lynette; MacSwain, Sarah; Clarke, James R
2013-08-01
Education in ethics is a requirement for all Royal College residency training programs as laid out in the General Standards of Accreditation for residency programs in Canada. The ethical challenges that face radiologists in clinical practice are often different from those that face other physicians, because the nature of the physician-patient interaction is unlike that of many other specialties. Ethics education for radiologists and radiology residents will benefit from the development of teaching materials and resources that focus on the issues that are specific to the specialty. This article is intended to serve as an educational resource for radiology training programs to facilitate teaching ethics to residents and also as a continuing medical education resource for practicing radiologists. In an environment of limited health care resources, radiologists are frequently asked to expedite imaging studies for patients and, in some respects, act as gatekeepers for specialty care. The issues of wait lists, queue jumping, and balancing the needs of individuals and society are explored from the perspective of a radiologist.
A jumping shape memory alloy under heat.
Yang, Shuiyuan; Omori, Toshihiro; Wang, Cuiping; Liu, Yong; Nagasako, Makoto; Ruan, Jingjing; Kainuma, Ryosuke; Ishida, Kiyohito; Liu, Xingjun
2016-02-16
Shape memory alloys are typical temperature-sensitive metallic functional materials due to superelasticity and shape recovery characteristics. The conventional shape memory effect involves the formation and deformation of thermally induced martensite and its reverse transformation. The shape recovery process usually takes place over a temperature range, showing relatively low temperature-sensitivity. Here we report novel Cu-Al-Fe-Mn shape memory alloys. Their stress-strain and shape recovery behaviors are clearly different from the conventional shape memory alloys. In this study, although the Cu-12.2Al-4.3Fe-6.6Mn and Cu-12.9Al-3.8Fe-5.6Mn alloys possess predominantly L2(1) parent before deformation, the 2H martensite stress-induced from L2(1) parent could be retained after unloading. Furthermore, their shape recovery response is extremely temperature-sensitive, in which a giant residual strain of about 9% recovers instantly and completely during heating. At the same time, the phenomenon of the jumping of the sample occurs. It is originated from the instantaneous completion of the reverse transformation of the stabilized 2H martensite. This novel Cu-Al-Fe-Mn shape memory alloys have great potentials as new temperature-sensitive functional materials.
Triple jump examinations for dental student assessment.
Navazesh, Mahvash; Rich, Sandra K; Chopiuk, Nasrin Bahari; Keim, Robert G
2013-10-01
The triple jump examination (TJE) attempts to assess a higher level of learning with demand for analysis, critical thinking, and resolution of problems presented by written scenarios based on patient care situations. The purpose of this study was to examine the internal consistency, scale reliability, and interrater reliability of the TJE used at the Ostrow School of Dentistry, University of Southern California. On the sample of 2,227 examinations administered by seventy-seven raters across a three-year time period, the Cronbach's coefficient alpha for internal consistency of the overall TJE was found to be good (a=0.869). The internal consistency of the three subscales was found to be acceptable (a=0.731), good (a=0.820), and good (a=0.820). Average and single measures intraclass correlation coefficients (ICC) for scale reliability were significant at p<0.001, indicating strong interrater reliability. There were no statistically significant differences (p≤0.05) in the mean scores assigned on the TJE between rater groups defined by rater experience level with the TJE. A very high level of agreement among rater pairs was also observed. Across the entire three-year study period, with over 19,152 ratings, the seventy-seven raters were in general agreement 99.5 percent of the time and in exact agreement 77.2 percent of the time.
SOLUTION TO BSDE WITH NONHOMOGENEOUS JUMPS UNDER LOCALLY LIPSCHITZIAN CONDITION
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
In this paper, we investigate the existence and uniqueness of the solution to a quasilinear backward stochastic differential equation with Poisson jumps. By introducing a series of approximate equations, we can show that BSDE has a unique adapted solution.
Spontaneous Jumping of Coalescing Drops on a Superhydrophobic Surface
Boreyko, Jonathan; Chen, Chuan-Hua
2009-11-01
When micrometric drops coalesce in-plane on a superhydrophobic surface, a surprising out-of-plane jumping motion was observed. Such jumping motion triggered by drop coalescence was reproduced on a Leidenfrost surface. High-speed imaging revealed that this jumping motion results from the elastic interaction of the bridged drops with the superhydrophobic/Leidenfrost surface. Experiments on both the superhydrophobic and Leidenfrost surfaces compare favorably to a simple scaling model relating the kinetic energy of the merged drop to the surface energy released upon coalescence. The spontaneous jumping motion on water repellent surfaces enables the autonomous removal of water condensate independently of gravity; this process is highly desirable for sustained dropwise condensation.
Spontaneous Jumping of Coalescing Drops on a Superhydrophobic Surface
Boreyko, Jonathan
2009-01-01
When micrometric drops coalesce in-plane on a superhydrophobic surface, a surprising out-of-plane jumping motion was observed. Such jumping motion triggered by drop coalescence was reproduced on a Leidenfrost surface. High-speed imaging revealed that this jumping motion results from the elastic interaction of the bridged drops with the superhydrophobic/Leidenfrost surface. Experiments on both the superhydrophobic and Leidenfrost surfaces compare favorably to a simple scaling model relating the kinetic energy of the merged drop to the surface energy released upon coalescence. The spontaneous jumping motion on water repellent surfaces enables the autonomous removal of water condensate independently of gravity; this process is highly desirable for sustained dropwise condensation.
Jump Testing and the Speed of Market Adjustment
DEFF Research Database (Denmark)
Rasmussen, Torben B.
Asymptotic properties of jump tests rely on the property that any jump occurs within a single time interval no matter what the observation frequency is. Market microstructure effects in relation to news-induced revaluation of the underlying variable is likely to make this an unrealistic assumption...... for high-frequency transaction data. To capture these microstructure effects, this paper suggests a model in which market prices adjust gradually to jumps in the underlying effcient price. A case study illustrates the empirical relevance of the model, and the performance of different jump tests...... is investigated here and in a simulation study. Evidence indicates that tests based on the largest of scaled price increments perform better than tests comparing measures of variability. Resolving the matter by testing at lower frequencies turns out to be less straightforward....
Stick-jump mode in surface droplet dissolution
Dietrich, Erik; Zhang, Xuehua; Zandvliet, Harold J W; Lohse, Detlef
2016-01-01
The analogy between evaporating surface droplets in air to dissolving long-chain alcohol droplets in water is worked out. We show that next to the three known modi for surface droplet evaporation or dissolution (constant contact angle mode, constant contact radius mode, and stick-slide mode), a fourth mode exists for small droplets on supposedly smooth substrates, namely the stick-jump mode: intermittent contact line pinning causes the droplet to switch between sticking and jumping during the dissolution. We present experimental data and compare them to theory to predict the dissolution time in this stick-jump mode. We also explain why these jumps were easily observed for microscale droplets but not for larger droplets.
METRIC TESTS CHARACTERISTIC FOR ESTIMATING JUMPING FOR VOLLEYBALL PLAYERS
Directory of Open Access Journals (Sweden)
Toplica Stojanović
2008-08-01
Full Text Available With goal to establish metric tests characteristics for estimating jumping for volleyball players, it was organized a pilot research on pattern of 23 volleyball players from cadet team and 23 students from high-school. For needs of this research four tests are valid for estimation, jump in block with left and right leg and jump in spike with left and right leg. Each test has been taken three times, so that we could with test-re test method determine their reliability, and with factor analysis their validity. Data were processed by multivariate analysis (item analysis, factor analysis from statistical package „Statistica 6.0 for windows“. On the results of research and discussion we can say that the tests had high coefficient of reliability, as well as factor validity, and these tests can be used to estimate jumping for volleyball players.
Bird Flu Strain May Have Jumped from Cat to Human
... page: https://medlineplus.gov/news/fullstory_162717.html Bird Flu Strain May Have Jumped From Cat to ... would be the first known transmission of this bird flu strain from cat to human, officials said. ...
Spontaneous azimuthal breakout and instability at the circular hydraulic jump
Ray, Arnab K; Basu, Abhik; Bhattacharjee, Jayanta K
2015-01-01
We consider a shallow, two-dimensional flow of a liquid in which the radial and the azimuthal dynamics are coupled to each other. The steady and radial background flow of this system creates an axially symmetric circular hydraulic jump. On this background we apply time-dependent perturbations of the matter flow rate and the azimuthal flow velocity, with the latter strongly localized at the hydraulic jump. The perturbed variables depend spatially on both the radial and azimuthal coordinates. Linearization of the perturbations gives a coupled system of wave equations. The characteristic equations extracted from these wave equations show that under a marginally stable condition a spontaneous breaking of axial symmetry occurs at the position of the hydraulic jump. Departure from the marginal stability shows further that a linear instability develops in the azimuthal direction, resulting in an azimuthal transport of liquid at the hydraulic jump. The time for the growth of azimuthal instability is scaled by viscosi...
The fluid dynamics of swimming by jumping in copepods
DEFF Research Database (Denmark)
Jiang, Houshuo; Kiørboe, Thomas
2011-01-01
Copepods swim either continuously by vibrating their feeding appendages or erratically by repeatedly beating their swimming legs resulting in a series of small jumps. The two swimming modes generate different hydrodynamic disturbances and therefore expose the swimmers differently to rheotactic...... limited and temporally ephemeral owing to jump-impulsiveness and viscous decay. In contrast, continuous steady swimming generates two well-extended long-lasting momentum jets both in front of and behind the swimmer, as suggested by the well-known steady stresslet model. Based on the observed jump-swimming...... kinematics of a small copepod Oithona davisae, we further showed that jump-swimming produces a hydrodynamic disturbance with much smaller spatial extension and shorter temporal duration than that produced by a same-size copepod cruising steadily at the same average translating velocity. Hence, small copepods...
The fluid dynamics of swimming by jumping in copepods
DEFF Research Database (Denmark)
Jiang, Houshuo; Kiørboe, Thomas
2011-01-01
Copepods swim either continuously by vibrating their feeding appendages or erratically by repeatedly beating their swimming legs resulting in a series of small jumps. The two swimming modes generate different hydrodynamic disturbances and therefore expose the swimmers differently to rheotactic...... limited and temporally ephemeral owing to jump-impulsiveness and viscous decay. In contrast, continuous steady swimming generates two well-extended long-lasting momentum jets both in front of and behind the swimmer, as suggested by the well-known steady stresslet model. Based on the observed jump-swimming...... kinematics of a small copepod Oithona davisae, we further showed that jump-swimming produces a hydrodynamic disturbance with much smaller spatial extension and shorter temporal duration than that produced by a same-size copepod cruising steadily at the same average translating velocity. Hence, small copepods...
Jump diffusion models and the evolution of financial prices
Energy Technology Data Exchange (ETDEWEB)
Figueiredo, Annibal; Castro, Marcio T. de [Institute of Physics, University of Brasilia (Brazil); Silva, Sergio da [Department of Economics, Federal University of Santa Catarina (Brazil); Gleria, Iram, E-mail: iram@pq.cnpq.br [Institute of Physics, Federal University of Alagoas (Brazil)
2011-08-08
We analyze a stochastic model to describe the evolution of financial prices. We consider the stochastic term as a sum of the Wiener noise and a jump process. We point to the effects of the jumps on the return time evolution, a central concern of the econophysics literature. The presence of jumps suggests that the process can be described by an infinitely divisible characteristic function belonging to the De Finetti class. We then extend the De Finetti functions to a generalized nonlinear model and show the model to be capable of explaining return behavior. -- Highlights: → We analyze a stochastic model to describe the evolution of financial prices. → The stochastic term is considered as a sum of the Wiener noise and a jump process. → The process can be described by an infinitely divisible characteristic function belonging to the De Finetti class. → We extend the De Finetti functions to a generalized nonlinear model.
Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method)
DEFF Research Database (Denmark)
Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan
Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf......Detection of Dew-Point by substantial Raman Band Frequency Jumps (A new Method). See poster at http://www.kemi.dtu.dk/~ajo/rolf/jumps.pdf...
Fundamental Studies of Jumping-Drop Thermal Diodes
2016-02-29
Reverse mode with liquid trapped by the colder superhydrophilic surface. ............... 2 Figure 2. Fabrication of the jumping-drop thermal diode...mode, Figure 1b), liquid water is trapped by it and no phase-change heat transfer takes place; heat mainly escapes through ineffective conduction...self- propelled jumping drops returning the working fluid from the colder superhydrophobic surface; (b) Reverse mode with liquid trapped by the colder
ANALYSIS OF INCOMPLETE STOCK MARKET WITH JUMP-DIFFUSION UNCERTAINTY
Institute of Scientific and Technical Information of China (English)
Xiuli Chao; Indrajit Bardhan
2002-01-01
This paper studies incomplete stock market that includes discontinuous priceprocesses. The discontinuity is modeled by very general point processes admitting onlystochastic intensities. Prices are driven by jump-diffusion uncertainty and have randombut predictable jumps. The space of risk-neutral measures that are associated with themarket is identified and related to fictitious completions. The construction of replicatingportfolios is discussed, and convex duality methods are used to prove existence of optimalconsumption and investment policies for a problem of utility maximization.
Nonlinear H∞ filtering for interconnected Markovian jump systems
Institute of Scientific and Technical Information of China (English)
Zhang Xiaomei; Zheng Yufan
2006-01-01
The problem of nonlinear H∞ filtering for interconnected Markovian jump systems is discussed. The aim of this note is the design of a nonlinear Markovian jump filter such that the resulting error system is exponentially meansquare stable and ensures a prescribed H∞ performance. A sufficient condition for the solvability of this problem is given in terms of linear matrix inequalities(LMIs). A simulation example is presented to demonstrate the effectiveness of the proposed design approach.
Psycho-physiological response in an automatic parachute jump
Clemente Suárez, Vicente Javier; Robles Pérez, José Juan; Fernández Lucas, Jesús
2016-01-01
Parachute jump is an extreme activity that elicits an intense stress response that affects jumpers' body systems being able to put them at risk. The present research analysed modifications in blood oxygen saturation (BOS), heart rate (HR), cortisol, glucose, lactate, creatine kinase (CK), muscles strength, cortical arousal, autonomic modulation, pistol magazine reload time (PMRT) and state anxiety before and after an automatic open parachute jump in 38 male Spanish soldiers (25.6 ± 5.9 years)...
Gravity-free hydraulic jumps and metal femtocups
Govindarajan, Rama; Mathur, Manikandan; DasGupta, Ratul; Selvi, N. R.; John, Neena Susan; Kulkarni, G. U.
2006-01-01
Hydraulic jumps created by gravity are seen every day in the kitchen sink. We show that at small scales a circular hydraulic jump can be created in the absence of gravity, by surface tension. The theory is motivated by our experimental finding of a height discontinuity in spreading submicron molten metal droplets created by pulsed-laser ablation. By careful control of initial conditions, we show that this leads to solid femtolitre cups of gold, silver, copper, niobium and tin.
Smoothed Particle Hydrodynamic of Hydraulic Jumps in Spillways
Jonsson, Patrick
2015-01-01
This thesis focus on the complex natural phenomena of hydraulic jumps using the numerical method Smoothed Particle Hydrodynamics (SPH). A hydraulic jump is highly turbulent and associated with turbulent energy dissipation, air entrainment, surface waves and spray and strong dissipative processes. It can be found not only in natural streams and in engineered open channels, but also in your kitchen sink at home. The dissipative features are utilized in hydropower spillways and stilling basins t...
Gravity-free hydraulic jumps and metal femtoliter cups.
Mathur, Manikandan; DasGupta, Ratul; Selvi, N R; John, Neena Susan; Kulkarni, G U; Govindarajan, Rama
2007-04-20
Hydraulic jumps created by gravity are seen everyday in the kitchen sink. We show that at small scales a circular hydraulic jump can be created in the absence of gravity by surface tension. The theory is motivated by our experimental finding of a height discontinuity in spreading submicron molten metal droplets created by pulsed-laser ablation. By careful control of initial conditions, this leads to solid femtoliter cups of gold, silver, copper, niobium, and tin.
On the Spectral Gap of Brownian Motion with Jump Boundary
Kolb, Martin
2011-01-01
In this paper we consider the Brownian motion with jump boundary and present a new proof of a recent result of Li, Leung and Rakesh concerning the exact convergence rate in the one-dimensional case. Our methods are different and mainly probabilistic relying on coupling methods adapted to the special situation under investigation. Moreover, we answer a question raised by Ben-Ari and Pinsky concerning the dependence of the spectral gap on the jump distribution in a multi-dimensional setting.
Forecasting Exchange Rate Volatility in the Presence of Jumps
DEFF Research Database (Denmark)
Busch, Thomas; Christensen, Bent Jesper; Nielsen, Morten Ørregaard
of exchange rate futures options, allowingcalculation of option implied volatility. We find that implied volatility is an informationallyeﬃcient but biased forecast of future realized exchange rate volatility. Furthermore,we show that log-normality is an even better distributional approximation...... for impliedvolatility than for realized volatility in this market. Finally, we show that the jump componentof future realized exchange rate volatility is to some extent predictable, and thatoption implied volatility is the dominant forecast of the future jump component....
A drop jumps to weightlessness: a lecture demo
Mayer, V. V.; Varaksina, E. I.; Saranin, V. A.
2017-04-01
The paper discusses the lecture demonstration of the phenomenon in which a drop lying on a solid unwettable substrate jumps when making the transition to weightlessness. An elementary theory of the phenomenon is given. A jump speed estimate is obtained for small and large drops. The natural vibrational frequency of a flying drop is determined. A full-scale model of Einstein’s elevator is described. Experimental and theoretical results are found to agree satisfactorily.
Importance sampling for jump processes and applications to finance
Badouraly Kassim, Laetitia; Lelong, Jérôme; Loumrhari, Imane
2013-01-01
International audience; Adaptive importance sampling techniques are widely known for the Gaussian setting of Brownian driven diffusions. In this work, we want to extend them to jump processes. Our approach relies on a change of the jump intensity combined with the standard exponential tilting for the Brownian motion. The free parameters of our framework are optimized using sample average approximation techniques. We illustrate the efficiency of our method on the valuation of financial derivat...
Temperature Jump Pyrolysis Studies of RP 2 Fuel
2017-01-09
Briefing Charts 3. DATES COVERED (From - To) 15 December 2016 – 11 January 2017 4. TITLE AND SUBTITLE Temperature Jump Pyrolysis Studies of RP-2 Fuel...Rev. 8- 98) Prescribed by ANSI Std. 239.18 1 TEMPERATURE JUMP PYROLYSIS STUDIES OF RP-2 FUEL Owen Pryor1, Steven D. Chambreau2, Ghanshyam L...Mixture Distribution A: Approved for public release; distribution unlimited. PA Clearance 17026 4 RP-2 Pyrolysis /Combustion Chemistries? • Recent
Dynamic Jump Intensities and Risk Premiums in Crude Oil Futures and Options Markets
DEFF Research Database (Denmark)
Christoffersen, Peter; Jacobs, Kris; Li, Bingxin
2016-01-01
and dynamic jump intensities in these markets. Allowing for jumps is crucial for modeling crude oil futures and futures options, and we find evidence in favor of time-varying jump intensities. During crisis periods, jumps occur more frequently. The properties of the jump processes implied by the option data......Options on crude oil futures are the most actively traded commodity options. We develop a class of computationally efficient discrete-time jump models that allow for closed-form option valuation, and we use crude oil futures and options data to investigate the economic importance of jumps...
Electric-Field-Enhanced Jumping-Droplet Condensation
Miljkovic, Nenad; Preston, Daniel; Enright, Ryan; Limia, Alexander; Wang, Evelyn
2013-11-01
When condensed droplets coalesce on a superhydrophobic surface, the resulting droplet can jump due to the conversion of surface energy into kinetic energy. This frequent out-of-plane droplet jumping has the potential to enhance condensation heat and mass transfer. In this work, we demonstrated that these jumping droplets accumulate positive charge that can be used to further increase condensation heat transfer via electric fields. We studied droplet jumping dynamics on silanized nanostructured copper oxide surfaces. By characterizing the droplet trajectories under various applied external electric fields (0 - 50 V/cm), we show that condensation on superhydrophobic surfaces results in a buildup of negative surface charge (OH-) due to dissociated water ion adsorption on the superhydrophobic coating. Consequently, the opposite charge (H3O +) accumulates on the coalesced jumping droplet. Using this knowledge, we demonstrate electric-field-enhanced jumping droplet condensation whereby an external electric field opposes the droplet vapor flow entrainment towards the condensing surface to increase the droplet removal rate and overall surface heat transfer by 100% when compared to state-of-the-art dropwise condensing surfaces. This work not only shows significant condensation heat transfer enhancement through the passive charging of condensed droplets, but promises a low cost approach to increase efficiency for applications such as atmospheric water harvesting and dehumidification.
Kinematic structure at the early flight position in ski jumping.
Vodičar, Janez; Coh, Milan; Jošt, Bojan
2012-12-01
The purpose of our research was to establish the variability of correlation between the length of the jumps and selected multi-item kinematic variables (n=9) in the early flight phase technique of ski jumping. This study was conducted on a sample of elite Slovenian ski jumpers (N=29) who participated in the experiment on a jumping hill in Hinterzarten, Germany (HS95m) on the 20(th) of August, 2008. The highest and most significant correlations (p=0.01) with the length of the ski jump were found in the multi-item variable height of flying, which was also expressed with the highest level of stability of the explained total variance (TV) on the first factor (TV=69.13%). The most important characteristic of the aerodynamic aspect of early flight was the variable angle between the body chord and the horizontal axis with significantly high correlations (pski and left leg (TV=50.13%), had an explained common variance on the first factor greater than 50% of total variance. The results indicated that some kinematic parameters of ski jumping early flight technique were more important for success considering the length of the jump.
Kinetic asymmetries between forward and drop jump landing tasks
Directory of Open Access Journals (Sweden)
Morgana Alves de Britto
2015-11-01
Full Text Available Landing asymmetry is a risk factor for knee anterior cruciate ligament injury. The aim of this study was to identify kinetic asymmetries in healthy recreational athletes performing different jump-landing techniques. Twelve recreational athletes engaged in regular training underwent kinetic evaluation using two 3D force plates and were analyzed for: (a three-dimensional peak forces, (b time to peak vertical force, and (c initial phase asymmetries. All data were collected during performance of unilateral and bilateral trials of forward and drop jump tasks. Forward jump-landing tasks elicited greater kinetic asymmetry than drop-landing tasks. Regardless of jump-landing technique, the preferred leg experienced higher forces than the non-preferred leg. The initial landing phase showed more kinetic asymmetries than the later phase when peak vertical forces occur. It was concluded that when screening athletes for kinetic asymmetries that may predispose them to injury, forward jump-landing tasks and the early landing phase might show more kinetic asymmetries than drop jump-landing tasks and the late landing phase, respectively.
The $k$-Tuple Jumping Champions among Consecutive Primes
Xiaosheng, Wu
2011-01-01
For any real $x$ and any integer $k\\ge1$, we say that a set $\\mathcal{D}_{k}$ of $k$ distinct integers is a $k$-tuple jumping champion if it is the most common differences that occurs among $k+1$ consecutive primes less than or equal to $x$. For $k=1$, it's known as the jumping champion introduced by J. H. Conway. In 1999 A. Odlyzko, M. Rubinstein, and M. Wolf announced the Jumping Champion Conjecture that the jumping champions greater than 1 are 4 and the primorials 2, 6, 30, 210, 2310,.... They also made a weaker and possibly more accessible conjecture that any fixed prime $p$ divides all sufficiently large jumping champions. These two conjectures were proved by Goldston and Ledoan under the assumption of appropriate forms of the Hardy-Littlewood conjecture recently. In the present paper we consider the situation for any $k\\ge2$ and prove that any fixed prime $p$ divides every element of all sufficiently large $k$-tuple jumping champions under the assumption that the Hardy-Littlewood prime $k+1$-tuple conje...
Bobbert, Maarten F; Santamaría, Susana; van Weeren, P René; Back, Wim; Barneveld, Albert
2005-09-01
The purpose of this study was to quantify performance characteristics of good jumping horses, and to determine whether these were already detectable at foal age. Kinematic data were collected of horses performing free jumps over a 0.60 m high fence at six months of age and of these same horses jumping with a rider over a 1.15 m high fence at five years of age. At five years of age the horses were divided into three groups on the basis of a puissance competition: a group of seven best jumpers that made no errors and in the end cleared a 1.50 m high fence, a group of nine worst jumpers that were unable to clear a 1.40 m high fence, and an intermediate group of 13 horses. Longitudinal kinematic data was available for all seven best jumpers and for six of the nine worst jumpers. Average values of variables for the best jumpers were compared with those of the worst jumpers for the jumps over 1.15 m. In the group of best jumpers, the forelimbs were shorter at forelimb clearance due to increased elbow flexion, and the hind limbs were further retroflexed at hind limb clearance. The same superior technique in clearing fences with the limbs was also found in this group at six months of age. Nevertheless, for individual horses it turned out to be too far-fetched to predict adult jumping capacity on the basis of kinematic variables collected during submaximal jumps at foal age.
Directory of Open Access Journals (Sweden)
Jun Zhang
2015-06-01
Full Text Available Jumping-height-and-distance (JHD active adjustment capability is important for jumping robots to overcome different sizes of obstacle. This paper proposes a new structural parameter-based JHD active adjustment approach for our previous jumping robot. First, the JHD adjustments, modifying the lengths of different legs of the robot, are modelled and simulated. Then, three mechanisms for leg-length adjustment are proposed and compared, and the screw-and-nut mechanism is selected. And for adjusting of different structural parameters using this mechanism, the one with the best JHD adjusting performance and the lowest mechanical complexity is adopted. Thirdly, an obstacle-distance-and-height (ODH detection method using only one infrared sensor is designed. Finally, the performances of the proposed methods are tested. Experimental results show that the jumping-height-and distance adjustable ranges are 0.11 m and 0.96 m, respectively, which validates the effectiveness of the proposed JHD adjustment method.
A comparison of pairs figure skaters in repeated jumps.
Sands, William A; Kimmel, Wendy L; McNeal, Jeni R; Murray, Steven Ross; Stone, Michael H
2012-01-01
Trends in pairs figure skating have shown that increasingly difficult jumps have become an essential aspect of high-level performance, especially in the latter part of a competitive program. We compared a repeated jump power index in a 60 s repeated jump test to determine the relationship of repeated jump test to competitive rank and to measure 2D hip, knee, and ankle angles and angular velocities at 0, 20, 40, and 60 s. Eighteen National Team Pairs Figure Skaters performed a 60 s repeated jump test on a large switch-mat with timing of flight and ground durations and digital video recording. Each 60-s period was divided into 6, 10-s intervals, with power indexes (W/kg) calculated for each 10-s interval. Power index by 10-s interval repeated measures ANOVAs (RMANOVA) showed that males exceeded females at all intervals, and the highest power index interval was during 10 to 20 s for both sexes. RMANOVAs of angles and angular velocities showed main effects for time only. Power index and jumping techniques among figure skaters showed rapid and steady declines over the test duration. Power index can predict approximately 50% of competitive rank variance, and sex differences in jumping technique were rare. Key pointsThe repeated jumps test can account for about 50% of the variance in pairs ranks.Changes in technique are largely due to fatigue, but the athletes were able to maintain a maximum flexion knee angle very close to the desired 90 degrees. Changes in angular velocity and jump heights occurred as expected, again probably due to fatigue.As expected from metabolic information, the athletes' power indexes peak around 20s and decline thereafter. Coaches should be aware of this time as a boundary beyond which fatigue becomes more manifest, and use careful choreographic choices to provide rest periods that are disguised as less demanding skating elements to afford recovery.The repeated jumps test may be a helpful off-ice test of power-endurance for figure skaters.
Effect of Instructions on Selected Jump Squat Variables.
Talpey, Scott W; Young, Warren B; Beseler, Bradley
2016-09-01
Talpey, SW, Young, WB, and Beseler, B. Effect of instructions on selected jump squat variables. J Strength Cond Res 30(9): 2508-2513, 2016-The purpose of this study was to compare 2 instructions on the performance of selected variables in a jump squat (JS) exercise. The second purpose was to determine the relationships between JS variables and sprint performance. Eighteen male subjects with resistance training experience performed 2 sets of 4 JS with no extra load with the instructions to concentrate on (a) jumping for maximum height and (b) extending the legs as fast as possible to maximize explosive force. Sprint performance was assessed at 0- to 10-m and 10- to 20-m distances. From the JS jump height, peak power, relative peak power, peak force, peak velocity, and countermovement distance were measured from a force platform and position transducer system. The JS variables under the 2 instructions were compared with paired t-tests, and the relationships between these variables and sprint performance were determined with Pearson's correlations. The jump height instruction produced greater mean jump height and peak velocity (p 0.05). Jump height was the variable that correlated most strongly with 10-m time and 10- to 20-m time under both instructions. The height instruction produced a stronger correlation with 10-m time (r = -0.455), but the fast leg extension JS produced a greater correlation with 10-20 time (r = -0.545). The results indicate that instructions have a meaningful influence on JS variables and therefore need to be taken into consideration when assessing or training athletes.
Scaling and jumping: gravity loses grip on small jumpers.
Scholz, Melanie N; Bobbert, Maarten F; Knoek van Soest, A J
2006-06-21
There are several ways to quantify jumping performance, a common definition being the height gained by the body's centre of mass (CM) in the airborne phase. Under this definition, jump height is determined by take-off velocity. According to the existing literature on jumping and scaling, take-off velocity, and hence jumping performance is independent of size because the energy that differently sized geometrically scaled jumpers can generate with their muscles is proportional to their mass. In this article it is shown, based on a simple energy balance, that it is incorrect to presume that jump height does not depend on size. Contrary to common belief, size as such has does have an effect on take-off velocity, putting small jumpers at a mechanical advantage, as is shown analytically. To quantify the effect of size on take-off velocity, a generic jumper model was scaled geometrically and evaluated numerically. While a 70-kg jumper took off at 2.65 m/s and raised its CM by 0.36 m after take-off, a perfectly geometrically similar jumper of 0.7 g reached a take-off velocity of 3.46 m/s and raised its CM by 0.61 m. The reason for the better performance of small jumpers is their higher efficacy in transforming the energy generated by the actuators into energy due to vertical velocity of the CM. Considering the ecological and evolutionary relevance of different definitions of jump height, size-dependent efficacy might explain why habitual jumping is especially prominent among small animals such as insects.
Isokinetic knee extension and vertical jumping: are they related?
Iossifidou, Anna; Baltzopoulos, Vasilios; Giakas, Giannis
2005-10-01
The aim of this study was to examine joint power generation during a concentric knee extension isokinetic test and a squat vertical jump. The isokinetic test joint power was calculated using four different methods. Five participants performed concentric knee extensions at 0.52, 1.57, 3.14 and 5.23 rad x s(-1) on a Lido isokinetic dynamometer. The squat vertical jump was performed on a Kistler force plate. Kinematic data from both tests were collected and analysed using an ELITE optoelectronic system. An inverse dynamics model was applied to measure knee joint moment in the vertical jump. Knee angular position data from the kinematic analysis in the isokinetic test were used to derive the actual knee angular velocity and acceleration, which, in turn, was used to correct the dynamometer moment for inertial effects. Power was measured as the product of angular velocity and moment at the knee joint in both tests. Significant differences (P knee joint power in the two tests (squat vertical jump: 2255 +/- 434 W; isokinetic knee extension: 771 +/- 81 W). Correlation analysis revealed that there is no relationship between the peak knee joint power during the vertical jump and the slow velocity isokinetic tests. Higher isokinetic velocity tests show better relationships with the vertical jump but only if the correct method for joint power calculation is used in the isokinetic test. These findings suggest that there are important differences in muscle activation and knee joint power development that must be taken into consideration when isokinetic tests are used to predict jumping performance.
The validity and reliability of an iPhone app for measuring vertical jump performance.
Balsalobre-Fernández, Carlos; Glaister, Mark; Lockey, Richard Anthony
2015-01-01
The purpose of this investigation was to analyse the concurrent validity and reliability of an iPhone app (called: My Jump) for measuring vertical jump performance. Twenty recreationally active healthy men (age: 22.1 ± 3.6 years) completed five maximal countermovement jumps, which were evaluated using a force platform (time in the air method) and a specially designed iPhone app. My jump was developed to calculate the jump height from flight time using the high-speed video recording facility on the iPhone 5 s. Jump heights of the 100 jumps measured, for both devices, were compared using the intraclass correlation coefficient, Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation and Bland-Altman plots. There was almost perfect agreement between the force platform and My Jump for the countermovement jump height (intraclass correlation coefficient = 0.997, P iPhone 5 s app.
The acute effect of vibration applications on jumping performance
Directory of Open Access Journals (Sweden)
Suat Yıldız
2012-12-01
Full Text Available Recently, vibration has become very popular as a method of exercise and training and drawn attention of researchers. The aim of this study was to analyses the acute affect of vibration applications as a method of exercise and training on jumping performance.In this study experimental group consists of 25 subjects who are studying at Physical Education and Sports Department of Sakarya University (age 22.2±1.7 years, height 179.2±4.8 cm. body weight 71.5±9.0 kg. This study included a vibration at density of 35 Hz (3x30 sec. frequency that result from aerobic exercise that has low density and b just methods of aerobic exercise (without any vibration that has low density. Subjects have taken the tests of countermovement and squat jumping after 2 minutes of each application. All applications and tests have been done in nonconsecutive days in a random scheme. In statistical analysis Wilcoxon has been applied in nonparametric scheme.For counter movement jumping; height of jumping, the difference between before and after the application of vibration related to the point of peak power and average power has been found significiant (respectively, p0.05; p>0.05; p>0.05.As a result, it is concluded that vibration that is applied at the range of 35 Hz frequency could increase the performance of acute countermovement jumping.
Mechanical parameters and flight phase characteristics in aquatic plyometric jumping.
Louder, Talin J; Searle, Cade J; Bressel, Eadric
2016-09-01
Plyometric jumping is a commonly prescribed method of training focused on the development of reactive strength and high-velocity concentric power. Literature suggests that aquatic plyometric training may be a low-impact, effective supplement to land-based training. The purpose of the present study was to quantify acute, biomechanical characteristics of the take-off and flight phase for plyometric movements performed in the water. Kinetic force platform data from 12 young, male adults were collected for counter-movement jumps performed on land and in water at two different immersion depths. The specificity of jumps between environmental conditions was assessed using kinetic measures, temporal characteristics, and an assessment of the statistical relationship between take-off velocity and time in the air. Greater peak mechanical power was observed for jumps performed in the water, and was influenced by immersion depth. Additionally, the data suggest that, in the water, the statistical relationship between take-off velocity and time in air is quadratic. Results highlight the potential application of aquatic plyometric training as a cross-training tool for improving mechanical power and suggest that water immersion depth and fluid drag play key roles in the specificity of the take-off phase for jumping movements performed in the water.
Jump point detection for real estate investment success
Hui, Eddie C. M.; Yu, Carisa K. W.; Ip, Wai-Cheung
2010-03-01
In the literature, studies on real estate market were mainly concentrating on the relation between property price and some key factors. The trend of the real estate market is a major concern. It is believed that changes in trend are signified by some jump points in the property price series. Identifying such jump points reveals important findings that enable policy-makers to look forward. However, not all jump points are observable from the plot of the series. This paper looks into the trend and introduces a new approach to the framework for real estate investment success. The main purpose of this paper is to detect jump points in the time series of some housing price indices and stock price index in Hong Kong by applying the wavelet analysis. The detected jump points reflect to some significant political issues and economic collapse. Moreover, the relations among properties of different classes and between stocks and properties are examined. It can be shown from the empirical result that a lead-lag effect happened between the prices of large-size property and those of small/medium-size property. However, there is no apparent relation or consistent lead in terms of change point measure between property price and stock price. This may be due to the fact that globalization effect has more impact on the stock price than the property price.
Unilateral jump behavior in young professional female ballet dancers.
Golomer, E; Féry, Y A
2001-09-01
In the field of dance, lateral body actions should be differently influenced by training. Classes should develop symmetrical jump behavior by the alternate working of the two body sides. In contrast, asymmetrical training effect linked to hemispheric laterality should be also expected. Indeed, for aesthetic reasons, the preferred led has to give the jump direction while the other leg has to carry out the impulsion during take-off. In addition, and for functional reasons, the preferred leg also has to ensure a soft landing and to avoid imbalance upon landing. To address the question, we studied ten professional right-footed female ballet dancers in a unilateral experimental task: the maximal vertical jump (MVJ). The MVJ height was compared for each leg in ten trials. In addition, the side of the leg usually involved in a choreographic bilateral task was determined. All these right-footed dancers selected their left leg as the impulsion leg for the choreographic jump so as to reserve the right leg for the expression of the artistic gesture linked to emotional laterality. However, ANOVA did not show differences between the right and left legs in MVJ. In these young ballerinas, jump actions of the two body sides seem to develop symmetrically by class training effects.
Volatility Forecasting: Downside Risk, Jumps and Leverage Effect
Directory of Open Access Journals (Sweden)
Francesco Audrino
2016-02-01
Full Text Available We provide empirical evidence of volatility forecasting in relation to asymmetries present in the dynamics of both return and volatility processes. Using recently-developed methodologies to detect jumps from high frequency price data, we estimate the size of positive and negative jumps and propose a methodology to estimate the size of jumps in the quadratic variation. The leverage effect is separated into continuous and discontinuous effects, and past volatility is separated into “good” and “bad”, as well as into continuous and discontinuous risks. Using a long history of the S & P500 price index, we find that the continuous leverage effect lasts about one week, while the discontinuous leverage effect disappears after one day. “Good” and “bad” continuous risks both characterize the volatility persistence, while “bad” jump risk is much more informative than “good” jump risk in forecasting future volatility. The volatility forecasting model proposed is able to capture many empirical stylized facts while still remaining parsimonious in terms of the number of parameters to be estimated.
CONNECTION OF FUNCTIONAL ABILITIES WITH JUMPING AND THROWING ATHLETIC DISCIPLINES
Directory of Open Access Journals (Sweden)
Igor Stanojević
2014-06-01
Full Text Available The aim of this study was to determine the connection between functional abilities with results of jumping and throwing athletic disciplines with athletes. The sample was taken from a population of elementary school students from Prokuplje region, 13 and 14 old, included in regular physical education classes. The sample consisted of 200 male athletes involved in the training process in sports clubs at least three times a week in addition to physical education classes. For assessment of functional abilities six functional tests were used: resting heart rate, Cooper test, heart rate in the first minute after Cooper test, heart rate in the second minute after Cooper test, systolic arterial blood pressure, diastolic arterial blood pressure. For assessment of jumping and throwing athletic disciplines four tests were used: long jump, high jump, shot put and javelin. Data analysis was performed with canonical correlation and regression analysis. The results showed a statistically significant correlation between functional abilities with all of tests in jumping and throwing athletic disciplines.
Biological Jumping Mechanism Analysis and Modeling for Frog Robot
Institute of Scientific and Technical Information of China (English)
Meng Wang; Xi-zhe Zang; Ji-zhuang Fan; Jie Zhao
2008-01-01
This paper presents a mechanical model of jumping robot based on the biological mechanism analysis of frog. By biological observation and kinematic analysis the frog jump is divided into take-off phase, aerial phase and landing phase. We find the similar trajectories of hindlimb joints during jump, the important effect of foot during take-off and the role of forelimb in supporting the body. Based on the observation, the frog jump is simplified and a mechanical model is put forward. The robot leg is represented by a 4-bar spring/linkage mechanism model, which has three Degrees of Freedom (DOF) at hip joint and one DOF (passive) at tarsometatarsal joint on the foot. The shoulder and elbow joints each has one DOF for the balancing function of arm.The ground reaction force of the model is analyzed and compared with that of frog during take-off. The results show that the model has the same advantages of low likelihood of premature lift-off and high efficiency as the frog. Analysis results and the model can be employed to develop and control a robot capable of mimicking the jumping behavior of flog.
Vertical jumping tests in volleyball: reliability, validity, and playing-position specifics.
Sattler, Tine; Sekulic, Damir; Hadzic, Vedran; Uljevic, Ognjen; Dervisevic, Edvin
2012-06-01
Vertical jumping is known to be important in volleyball, and jumping performance tests are frequently studied for their reliability and validity. However, most studies concerning jumping in volleyball have dealt with standard rather than sport-specific jumping procedures and tests. The aims of this study, therefore, were (a) to determine the reliability and factorial validity of 2 volleyball-specific jumping tests, the block jump (BJ) test and the attack jump (AJ) test, relative to 2 frequently used and systematically validated jumping tests, the countermovement jump test and the squat jump test and (b) to establish volleyball position-specific differences in the jumping tests and simple anthropometric indices (body height [BH], body weight, and body mass index [BMI]). The BJ was performed from a defensive volleyball position, with the hands positioned in front of the chest. During an AJ, the players used a 2- to 3-step approach and performed a drop jump with an arm swing followed by a quick vertical jump. A total of 95 high-level volleyball players (all men) participated in this study. The reliability of the jumping tests ranged from 0.97 to 0.99 for Cronbach's alpha coefficients, from 0.93 to 0.97 for interitem correlation coefficients and from 2.1 to 2.8 for coefficients of variation. The highest reliability was found for the specific jumping tests. The factor analysis extracted one significant component, and all of the tests were highly intercorrelated. The analysis of variance with post hoc analysis showed significant differences between 5 playing positions in some of the jumping tests. In general, receivers had a greater jumping capacity, followed by libero players. The differences in jumping capacities should be emphasized vis-a-vis differences in the anthropometric measures of players, where middle hitters had higher BH and body weight, followed by opposite hitters and receivers, with no differences in the BMI between positions.
Effects of kettlebell training on postural coordination and jump performance
DEFF Research Database (Denmark)
Jay, Kenneth; Jakobsen, Markus Due; Sundstrup, Emil
2013-01-01
ABSTRACT: The aim of this study was to investigate the effectiveness of a worksite intervention using kettlebell training to improve postural reactions to perturbation and jump performance.This single-blind randomized controlled trial involved 40 adults (n=40) from occupations with a high....... The outcome measures were postural reactions to sudden perturbation and maximal countermovement jump height.Compared to the control group, the training group significant decreased stopping time following perturbation (-109ms, 95% CI [-196:-21]). Jump height increased significantly in the training group (1.5cm......, 95% CI [0.5:2.5]), but this was non-significantly different from control.Kettlebell training improves postural reactions to sudden perturbation. Future studies should investigate whether kettlebell training can reduce the risk of low-back injury in occupations with manual material handling or patient...
Physiological arousal and perception of bodily state during parachute jumping.
Schedlowski, M; Tewes, U
1992-01-01
Heart rate and respiration rate were recorded with a portable data recording system before and during a parachute jump in 36 male sport parachutists with differing degrees of experience. The recordings were analyzed at 12 psychologically relevant points in time along with the subjective ratings of physical arousal. Novice parachutists showed a higher degree of self-rated arousal during jumps. However, the two groups displayed nearly parallel curves for heart and respiration rates, differing significantly from each other only in the level of their respective heart rates. Furthermore, experienced jumpers seem to be better informed about their state of physiological arousal during the jump than are novice jumpers. These results do not confirm the proposed anxiety inhibition process, postulated by Epstein (1967).
Condensation and jumping relay of droplets on lotus leaf
Lv, Cunjing; Hao, Pengfei; Yao, Zhaohui; Song, Yu; Zhang, Xiwen; He, Feng
2013-07-01
Dynamic behavior of micro water droplet condensed on a lotus leaf with two-tier roughness is studied. Under laboratory environment, the contact angle of the micro droplet on single micro papilla increases smoothly from 80° to 160° during the growth of condensed water. The best-known "self-cleaning" phenomenon will be lost. A striking observation is the out-of-plane jumping relay of condensed droplets triggered by falling droplets, as well as its sustained speed obtained in continuous jumping relays. The underlying mechanism can be used to enhance the automatic removal of dropwise condensation without the help from any external force. The surface tension energy dissipation is the main reason controlling the critical size of jumping droplet and its onset velocity of rebounding.
Dynamical Jumps in a Shape Memory Alloy Oscillator
Directory of Open Access Journals (Sweden)
H. S. Oliveira
2014-01-01
Full Text Available The dynamical response of systems with shape memory alloy (SMA elements presents a rich behavior due to their intrinsic nonlinear characteristic. SMA’s nonlinear response is associated with both adaptive dissipation related to hysteretic behavior and huge changes in properties caused by phase transformations. These characteristics are attracting much technological interest in several scientific and engineering fields, varying from medical to aerospace applications. An important characteristic associated with dynamical response of SMA system is the jump phenomenon. Dynamical jumps result in abrupt changes in system behavior and its analysis is essential for a proper design of SMA systems. This paper discusses the nonlinear dynamics of a one degree of freedom SMA oscillator presenting pseudoelastic behavior and dynamical jumps. Numerical simulations show different aspects of this kind of behavior, illustrating its importance for a proper understanding of nonlinear dynamics of SMA systems.
Aerodynamic Jump: A Short Range View for Long Rod Projectiles
Directory of Open Access Journals (Sweden)
Mark Bundy
2001-01-01
Full Text Available It is shown that aerodynamic jump for a nonspinning kinetic energy penetrator is not – as conventional definitions may infer – a discontinuous change in the direction of motion at the origin of free flight, nor is it the converse, a cumulative redirection over a domain of infinite extent. Rather, with the aid of an alternative kinematical definition, it is shown that aerodynamic jump for such a projectile is a localized redirection of the center-of-gravity motion, caused by the force of lift due to yaw over the relatively short region from entry into free flight until the yaw reaches its first maximum. A rigorous proof of this statement is provided, but the primary objective of this paper is to provide answers to the questions: what is aerodynamic jump, what does it mean, and what aspects of the flight trajectory does it refer to, or account for.
Multiple Tune Jumps to Overcome Horizontal Depolarizing Resonances
Huang, H.; Ahrens, L. A.; Bai, M.; Brown, K. A.; Dutheil, Y.; Gardner, C.; Glenn, J. W.; Lin, F.; Mackay, W. W.; Meot, F.; Poblaguev, A.; Ranjbar, V.; Roser, T.; Schoefer, V.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.
2016-02-01
Imperfection and vertical intrinsic depolarizing resonances have been overcome by the two partial Siberian snakes in the Alternative Gradient Synchrotron(AGS). The relatively weak but numerous horizontal resonances are the main source of polarization loss in the AGS. A pair of horizontal tune jump quads have been used to overcome these weak resonances. The locations of the two quads have to be chosen such that the disturbance to the beam optics is minimum. The emittance growth has to be mitigated for this method to work. In addition, this technique needs very accurate jump timing. Using two partial Siberian snakes, with vertical tune inside the spin tune gap and 80% polarization at AGS injection, polarized proton beam had reached 1.5 × 1011 proton per bunch with 65% polarization. With the tune jump timing optimized and emittance preserved, more than 70% polarization with 2 × 1011 protons per bunch has been achieved.
Condensation and jumping relay of droplets on lotus leaf
Lv, Cunjing; Yao, Zhaohui; Song, Yu; Zhang, Xiwen; He, Feng
2013-01-01
Dynamic behavior of micro water droplet condensed on a lotus leaf with two-tier roughness is studied. Under laboratory environment, the contact angle of the micro droplet on single micro papilla increases smoothly from 80 deg to 160 deg during the growth of condensed water. The best-known "self-clean" phenomenon, will be lost. A striking observation is the out-of-plane jumping relay of condensed droplets triggered by falling droplets, as well as its sustained speed obtained in continuous jumping relays, enhance the automatic removal of dropwise condensation without the help from any external force. The surface tension energy dissipation is the main reason controlling the critical size of jumping droplet and its onset velocity of rebounding.
Vertical Jump Biomechanics Altered With Virtual Overhead Goal.
Ford, Kevin R; Nguyen, Anh-Dung; Hegedus, Eric J; Taylor, Jeffrey B
2017-04-01
Virtual environments with real-time feedback can simulate extrinsic goals that mimic real life conditions. The purpose was to compare jump performance and biomechanics with a physical overhead goal (POG) and with a virtual overhead goal (VOG). Fourteen female subjects participated (age: 18.8 ± 1.1 years, height: 163.2 ± 8.1 cm, weight 63.0 ± 7.9 kg). Sagittal plane trunk, hip, and knee biomechanics were calculated during the landing and take-off phases of drop vertical jump with different goal conditions. Repeated-measures ANOVAs determined differences between goal conditions. Vertical jump height displacement was not different during VOG compared with POG. Greater hip extensor moment (P biomechanical testing, screening, and training conditions.
The acute effect of vibration applications on jumping performance
Directory of Open Access Journals (Sweden)
Şener Soylu
2012-12-01
Full Text Available Recently, vibration has become very popular as a method of exercise and training and drawn attention of researchers. The aim of this study was to analyses the acute affect of vibration applications as a method of exercise and training on jumping performance. In this study experimental group consists of 25 subjects who are studying at Physical Education and Sports Department of Sakarya University (age 22.2±1.7 years, height 179.2±4.8 cm. body weight 71.5±9.0 kg. This study included a vibration at density of 35 Hz (3x30 sec. frequency that result from aerobic exercise that has low density and b just methods of aerobic exercise (without any vibration that has low density. Subjects have taken the tests of countermovement and squat jumping after 2 minutes of each application. All applications and tests have been done in nonconsecutive days in a random scheme. In statistical analysis Wilcoxon has been applied in nonparametric scheme. For counter movement jumping; height of jumping, the difference between before and after the application of vibration related to the point of peak power and average power has been found significiant (respectively, p<0.05; p<0.05; p<0.01. In addition to this, no statistical difference was found for squat vertical jumping before and after the application of vibration related to the point of peak power and average power (respectively, p>0.05; p>0.05; p>0.05. As a result, it is concluded that vibration that is applied at the range of 35 Hz frequency could increase the performance of acute countermovement jumping.
Coalescence-induced jumping of droplet: Inertia and viscosity effects
Farokhirad, Samaneh; Morris, Jeffrey F.; Lee, Taehun
2015-10-01
The problem of coalescence-induced self-propelled jumping of droplet is studied using three-dimensional numerical simulation. The focus is on the effect of inertia and in particular the effect of air density on the behavior of the merged droplet during jumping. A lattice Boltzmann method is used for two identical, static micro-droplets coalescing on a homogeneous substrate with contact angle ranging from 0∘ to 180∘. The results reveal that the effect of air density is significant on detachment of the merged droplet from the substrate at the later stage of the jumping process; the larger the air density, the larger the jumping height of the droplet. Analysis of streamlines and vorticity contours is performed for density ratios ranging from 60 to 800. These show a generation of vortical structures inside and around the droplet. The intensity of these structures gets weaker after droplet departure as the air inertia is decreased. The results are also presented in terms of phase diagrams of the merged droplet jumping for different Ohnesorge numbers (Oh) and surface wettabilities for both small and large density ratios. The critical value of contact angle where the merged droplet jumps away from the substrate is independent of density ratio and has a value around 150∘. However, the critical value of Oh depends on both density ratio and wettability of the surface for contact angles greater than 150∘. In this range of contact angle, the diagrams show two distinct dynamical regimes for different density ratios, namely, inertial and viscous regimes.
AirJump: Using Interfaces to Instantly Perform Simultaneous Extractions.
Berry, Scott M; Pezzi, Hannah M; LaVanway, Alex J; Guckenberger, David J; Anderson, Meghan A; Beebe, David J
2016-06-22
Analyte isolation is an important process that spans a range of biomedical disciplines, including diagnostics, research, and forensics. While downstream analytical techniques have advanced in terms of both capability and throughput, analyte isolation technology has lagged behind, increasingly becoming the bottleneck in these processes. Thus, there exists a need for simple, fast, and easy to integrate analyte separation protocols to alleviate this bottleneck. Recently, a new class of technologies has emerged that leverages the movement of paramagnetic particle (PMP)-bound analytes through phase barriers to achieve a high efficiency separation in a single or a few steps. Specifically, the passage of a PMP/analyte aggregate through a phase interface (aqueous/air in this case) acts to efficiently "exclude" unbound (contaminant) material from PMP-bound analytes with higher efficiency than traditional washing-based solid-phase extraction (SPE) protocols (i.e., bind, wash several times, elute). Here, we describe for the first time a new type of "exclusion-based" sample preparation, which we term "AirJump". Upon realizing that much of the contaminant carryover stems from interactions with the sample vessel surface (e.g., pipetting residue, wetting), we aim to eliminate the influence of that factor. Thus, AirJump isolates PMP-bound analyte by "jumping" analyte directly out of a free liquid/air interface. Through careful characterization, we have demonstrated the validity of AirJump isolation through comparison to traditional washing-based isolations. Additionally, we have confirmed the suitability of AirJump in three important independent biological isolations, including protein immunoprecipitation, viral RNA isolation, and cell culture gene expression analysis. Taken together, these data sets demonstrate that AirJump performs efficiently, with high analyte yield, high purity, no cross contamination, rapid time-to-isolation, and excellent reproducibility.
Sponsored parachute jumps--can they cause prolonged pain?
Straiton, N; Sterland, J
1986-01-01
A survey of parachute injuries sustained in 1984 at a local parachute club was made using hospital notes and a questionnaire. The overall injury rate was 0.2%. The injury rate in first time jumpers was 1.1%. The injuries often resulted in a prolonged hospital stay, time off work and residual pain and disability. Injury rates may be reduced by more prolonged and intensive training preceding the first jumps. Those people not interested in parachuting as a regular sport and who jump once only in...
Sponsored parachute jumps--can they cause prolonged pain?
Straiton, N; Sterland, J
1986-06-01
A survey of parachute injuries sustained in 1984 at a local parachute club was made using hospital notes and a questionnaire. The overall injury rate was 0.2%. The injury rate in first time jumpers was 1.1%. The injuries often resulted in a prolonged hospital stay, time off work and residual pain and disability. Injury rates may be reduced by more prolonged and intensive training preceding the first jumps. Those people not interested in parachuting as a regular sport and who jump once only in order to raise money for charity are at risk of serious injury and perhaps should consider less dangerous alternatives.
ASCAN Helms simulates parachute jump during VAFB training exercises
1990-01-01
1990 Group 13 Astronaut Candidate (ASCAN) Susan J. Helms simulates a parachute jump during ground egress and parasail training exercises at Vance Air Force Base (VAFB), Enid, Oklahoma. With her arms folded against her chest, Helms jumps from a brick platform onto the ground. In line behind her are Charles J. Precourt followed by Leroy Chiao. The training is designed to prepare the ASCANs for proper survival measures to take in the event of an emergency aboard the T-38 jet trainer aircraft they will frequently use once they become full-fledged astronauts. ASCANs completed the VAFB training courses from 07-29-90 through 07-31-90.
Hydrodynamics and energetics of jumping copepod nauplii and copepodids
DEFF Research Database (Denmark)
Wadhwa, Navish; Andersen, Anders Peter; Kiørboe, Thomas
2014-01-01
, we measured the swimming kinematics and fluid flow around jumping Acartia tonsa at different stages of its life cycle, using particle image velocimetry and particle tracking velocimetry. We found that the flow structures around nauplii and copepodids are topologically different, with one and two...... vortex rings, respectively. Our measurements suggest that copepodids cover a larger distance compared to their body size in each jump and are also hydrodynamically quieter, as the flow disturbance they create attenuates faster with distance. Also, copepodids are energetically more efficient than nauplii...
Aerodynamic Jump: A Short Range View for Long Rod Projectiles
Mark Bundy
2001-01-01
It is shown that aerodynamic jump for a nonspinning kinetic energy penetrator is not – as conventional definitions may infer – a discontinuous change in the direction of motion at the origin of free flight, nor is it the converse, a cumulative redirection over a domain of infinite extent. Rather, with the aid of an alternative kinematical definition, it is shown that aerodynamic jump for such a projectile is a localized redirection of the center-of-gravity motion, caused by the force of lift ...
Jumps into democracy: The transition in the Polity Index
DEFF Research Database (Denmark)
Paldam, Martin; Gundlach, Erich
The Democratic Transition is the process of regime change from authoritarian at the traditional level of development to democratic at the modern level. This process is analyzed on 7,565 pairs of income and political regime data. Regimes are normally in local status quo equilibrium, so they have s......-run changes are due to triggering events that cause regime jumps. Triggering events are almost random, while most jumps are in the direction of the tension. This mechanism integrates the short and the long run to give the transition....
Tunneling of the blocked wave in a circular hydraulic jump
Bhattacharjee, Jayanta K.
2017-02-01
The formation of a circular hydraulic jump in a thin liquid layer involves the creation of a horizon where the incoming wave (surface ripples) is blocked by the fast flowing fluid. That there is a jump at the horizon is due to the viscosity of the fluid which is not relevant for the horizon formation. By using a tunneling formalism developed for the study of the Hawking radiation from black holes, we explicitly show that there will be an exponentially small tunneling of the blocked wave across the horizons as anticipated in studies of "analog gravity".
Pricing Participating Products under a Generalized Jump-Diffusion Model
Directory of Open Access Journals (Sweden)
Tak Kuen Siu
2008-01-01
Full Text Available We propose a model for valuing participating life insurance products under a generalized jump-diffusion model with a Markov-switching compensator. It also nests a number of important and popular models in finance, including the classes of jump-diffusion models and Markovian regime-switching models. The Esscher transform is employed to determine an equivalent martingale measure. Simulation experiments are conducted to illustrate the practical implementation of the model and to highlight some features that can be obtained from our model.
Actionable Information, Repeatability, Quantum Jumps, and the Wavepacket Collapse
Zurek, Wojciech H
2013-01-01
Unknown quantum state cannot be discovered as the measured system is re-prepared -- it jumps into an eigenstate of the measured observable. This impossibility to find out a quantum state and other symptoms of the wavepacket collapse follow (as was recently demonstrated for pure states of measured systems) from unitarity (that doesn't, however, allow for a literal collapse) and from the repeatability of measurements. Here we extend this result to mixtures and decohering systems. This accounts for quantum jumps in a macroscopic and open (but ultimately quantum) apparatus.
Does gymnastics practice improve vertical jump reliability from the age of 8 to 10 years?
Marina, Michel; Torrado, Priscila
2013-01-01
The objective of this study was to confirm whether gymnastics practice from a young age can induce greater vertical jump reliability. Fifty young female gymnasts (8.84 ± 0.62 years) and 42 females in the control group (8.58 ± 0.92 years) performed the following jump tests on a contact mat: squat jump, countermovement jump, countermovement jump with arm swing and drop jump from heights of 40 and 60 cm. The two testing sessions had three trials each and were separated by one week. A 2 (groups) × 2 (sessions) × 3 (trials) repeated measures analysis of variance (ANOVA) and a test-retest correlation analysis were used to study the reliability. There was no systematic source of error in either group for non-plyometric jumps such as squat jump, countermovement jump, and countermovement jump with arm swing. A significant group per trial interaction revealed a learning effect in gymnasts' drop jumps from 40 cm height. Additionally, the test-retest correlation analysis and the higher minimum detectable error suggest that the quick drop jump technique was not fully consolidated in either group. At an introductory level of gymnastics and between the ages of 8-10 years, the condition of being a gymnast did not lead to conclusively higher reliability, aside from better overall vertical jump performance.
Kale, Mehmet; Aşçi, Alper; Bayrak, Coşkun; Açikada, Caner
2009-11-01
The purpose of this study was to investigate the relationships among jumping performances and speed parameters during maximum speed phase in sprinters. Twenty-one men sprinters volunteered to participate at the beginning of the preparation training phase. All tests-including 100-m sprint running, squat jump (SJ), countermovement jump (CMJ), drop jump (DJ), 60-second repetitive jump (RJ), standing long jump (SLJ), standing triple jump (STJ), standing quintuple jump (SQJ), and standing 10-stride jump (STENJ)-were done on switching mats. Flight (FT) and contact times (CT) during the vertical jump tests and 10-m split times during 100-m sprint running were measured by a 2-channel precision timing system (PTS) connected to the mats. The trace marking method was used for measuring the stride length (SL) through 60 m in 100-m sprint running. Stride frequency (SF), maximum velocity (Vmax), jump height for all vertical jumps, and lower-body power in DJ and RJ were calculated. Statistical analysis showed that the highest significant correlation was found between Vmax and DJ height (r = 0.69; p sprint running and SJ (r = 0.39; p sprint running than the other vertical and horizontal jump tests at the beginning of the preparation training phase.
Suicides by jumping from a height in Hong Kong: a review of coroner court files.
Wong, Paul W C; Caine, Eric D; Lee, Carmen K M; Beautrais, Annette; Yip, Paul S F
2014-02-01
Jumping from a height is the most common method for suicide in Hong Kong and other urban cities, but it remains understudied locally and internationally. We used Coroner records in exploring the ecological factors associated with these deaths and the personal characteristics of persons who jumped to their death (hereafter, "jumping suicides"). We compared suicides by jumping with all other suicides and examined the suicides that occurred at ten different jumping sites. The Coroner's files of all suicides in Hong Kong from 2002 to 2007 included 6,125 documented deaths. 2,964 (48.4%) involved jumping during the study period. Eighty-three percent (83%) of suicide jumps occurred in residential buildings, and of these, 61% occurred from the decedent's own home. Jumping suicides differed from non-jumping suicides in terms of their socio-demographic characteristics (e.g., for male: 60.8 vs. 67.3% of jumping suicide and non-jumping suicides, p suicides, p suicides (p suicide prevention. Installation of physical barriers, one of the mean restriction strategies, at common places for suicide has strong evidence to avert suicides without substitution effects. There seems to be challenges to implement physical barriers to prevent residential jumping suicides. Simply applying physical barriers to preclude jumping in Hong Kong appears to be difficult given its ubiquitous "high-rise" residential dwellings. Hence, we also need to develop alternative strategies aimed at preventing people from becoming suicidal.
Application of biological feedback for estimation of anaerobic performance in jumping test
Directory of Open Access Journals (Sweden)
Kovalenko S.O.
2014-10-01
Full Text Available Purpose : - To determine the effect of biofeedback to determine the level of anaerobic performance of healthy young men. Material: The characteristics of physical performance in 60-seconds jumping test without and with visual and audible biofeedback (BFB are determined at 23 healthy young men. Results : Significant individual peculiarities are found in performance features of 60-seconds jumping test both without and with BFB. The groups of performance indexes are maximum jumping height; jumping frequency and achieved performance level; correlation of jumping phases and achieved capacity of a separate jump; jumping dynamics during the test. The positive effect mostly on performance in BFB regime is found in the group of persons with low level of physical performance. Conclusion : The application of BFB in 60-seconds jumping test is proved to increase the objective character of measuring anaerobic performance.
Aerobic Requirements for and Heart Rate Responses to Variations in Rope Jumping Techniques.
Solis, Ken; And Others
1988-01-01
Highly skilled ropejumpers can maintain their exercise intensity by varying their jumping technique. Research on heart rate responses and aerobic requirements of different jumping techniques is discussed. Methodology and data are reported. (Author/JL)
Lenoir, Matthieu; De Clercq, Dirk; Laporte, Willy
2005-10-01
A plausible explanation for the ancient long jump records from Greek antiquity is sought on the basis of pictorial and written sources, and corroborated with practical tests. Ancient sources report that athletes jumped more than 15 m with weights in their hands, which enabled them to jump further than without these weights. It is proposed that the ancient Greek long jump was a continuous succession of five standing broad jumps, in which the landing phase of one jump was also the countermovement for the next jump. Four trained athletes jumped further with (14.64 +/- 0.76 m, range 13.64-15.63 m) than without weights (13.88 +/- 0.70 m, range 12.60-14.75 m; P = 0.001). These results show that this technique is executable, fits with ancient written and pictorial sources, and allows trained modern athletes to jump distances well over 15 m. The extra distance jumped when using weights may be due to changes in the position of the jumper's centre of mass at take-off and at landing, and an increase in take-off velocity stemming from several biomechanical mechanisms.
Mechanically induced ankle inversion during human walking and jumping.
Nieuwenhuijzen, P.H.J.A.; Grüneberg, C.; Duysens, J.E.J.
2002-01-01
A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 25 degrees were elicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delay after left heel strike, an electromagnet
Structural estimation of jump-diffusion processes in macroeconomics
DEFF Research Database (Denmark)
Posch, Olaf
2009-01-01
This paper shows how to solve and estimate a continuous-time dynamic stochastic general equilibrium (DSGE) model with jumps. It also shows that a continuous-time formulation can make it simpler (relative to its discrete-time version) to compute and estimate the deep parameters using the likelihoo...
Jump Conditions for Maxwell Equations and Their Consequences
2013-01-28
critical issues in computational modeling of electromagnetic systems containing sliding contacts, such as railguns , is the relationship between...an armature is propelled by electromagnetic force. Two stationary conductors (rails) are connected to a capacitor bank. An armature, typically a solid...experimental results. 15. SUBJECT TERMS Maxwell equation, computational electromagnetics , jump condition 16. SECURITY CLASSIFICATION OF: 17
Environmentally transmitted parasites: Host-jumping in a heterogeneous environment.
Caraco, Thomas; Cizauskas, Carrie A; Wang, Ing-Nang
2016-05-21
Groups of chronically infected reservoir-hosts contaminate resource patches by shedding a parasite׳s free-living stage. Novel-host groups visit the same patches, where they are exposed to infection. We treat arrival at patches, levels of parasite deposition, and infection of the novel host as stochastic processes, and derive the expected time elapsing until a host-jump (initial infection of a novel host) occurs. At stationarity, mean parasite densities are independent of reservoir-host group size. But within-patch parasite-density variances increase with reservoir group size. The probability of infecting a novel host declines with parasite-density variance; consequently larger reservoir groups extend the mean waiting time for host-jumping. Larger novel-host groups increase the probability of a host-jump during any single patch visit, but also reduce the total number of visits per unit time. Interaction of these effects implies that the waiting time for the first infection increases with the novel-host group size. If the reservoir-host uses resource patches in any non-uniform manner, reduced spatial overlap between host species increases the waiting time for host-jumping.
Delayed Frost Growth on Jumping-Drop Superhydrophobic Surfaces
Energy Technology Data Exchange (ETDEWEB)
Boreyko, Jonathan B [ORNL; Collier, Pat [ORNL
2013-01-01
Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an inter-drop frost wave. The growth of this inter-drop frost front is shown to be up to three times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of inter-drop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an inter-drop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser was found to be superior to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by minimizing the success of interdrop ice bridge formation.
Delayed frost growth on jumping-drop superhydrophobic surfaces.
Boreyko, Jonathan B; Collier, C Patrick
2013-02-26
Self-propelled jumping drops are continuously removed from a condensing superhydrophobic surface to enable a micrometric steady-state drop size. Here, we report that subcooled condensate on a chilled superhydrophobic surface are able to repeatedly jump off the surface before heterogeneous ice nucleation occurs. Frost still forms on the superhydrophobic surface due to ice nucleation at neighboring edge defects, which eventually spreads over the entire surface via an interdrop frost wave. The growth of this interdrop frost front is shown to be up to 3 times slower on the superhydrophobic surface compared to a control hydrophobic surface, due to the jumping-drop effect dynamically minimizing the average drop size and surface coverage of the condensate. A simple scaling model is developed to relate the success and speed of interdrop ice bridging to the drop size distribution. While other reports of condensation frosting on superhydrophobic surfaces have focused exclusively on liquid-solid ice nucleation for isolated drops, these findings reveal that the growth of frost is an interdrop phenomenon that is strongly coupled to the wettability and drop size distribution of the surface. A jumping-drop superhydrophobic condenser minimized frost formation relative to a conventional dropwise condenser in two respects: preventing heterogeneous ice nucleation by continuously removing subcooled condensate, and delaying frost growth by limiting the success of interdrop ice bridge formation.
Jump Patterns: Percussive Dance and the Path to Math
Rosenfeld, Malke
2011-01-01
In this article, the author describes an innovative collaboration with an elementary school math teacher that leads to original student choreography and engaging mathematical thinking. Using a tool the author created called Jump Patterns, students at Fox Hill Elementary School in Indianapolis, Indiana, engage in a robust, creative, choreographic…
A logarithmic interpretation of Edixhoven's jumps for Jacobians
DEFF Research Database (Denmark)
Eriksson, Dennis; Halle, Lars Halvard; Nicaise, Johannes
2015-01-01
Let A be an abelian variety over a discretely valued field. Edixhoven has defined a filtration on the special fiber of the N\\'eron model of A that measures the behaviour of the N\\'eron model under tame base change. We interpret the jumps in this filtration in terms of lattices of logarithmic...
The Hydraulic Jump: Finding Complexity in Turbulent Water
Vondracek, Mark
2013-01-01
Students who do not progress to more advanced science disciplines in college generally do not realize that seemingly simple physical systems are--when studied in detail--more complex than one might imagine. This article presents one such phenomenon--the hydraulic jump--as a way to help students see the complexity behind the seemingly simple, and…
Anticipating the Species Jump: Surveillance for Emerging Viral Threats
2010-12-01
broken skin or injection). Tropism is the affinity that a given virus has for particular host cell receptors, cells or tissues. Fusion/Entry...be a descendant of a cat virus ( feline panleukopenia virus, FPV) that jumped from cats to dogs within five years prior to its emergence. Since that
The Viability Property of Controlled Jump Diffusion Processes
Institute of Scientific and Technical Information of China (English)
Shi Ge PENG; Xue Hong ZHU
2008-01-01
In this paper,we first give a comparison theorem of viscosity solution to some nonlinear second order integrodifferential equation.And then using the comparison theorem,we obtain a necessary and sufficient condition for the viability property of some controlled jump diffusion processes which can keep the solution within a constraint K.
Jumping across the gap - a series of atrial extrastimuli.
Swamy, Mahadeva; Katyal, Deepak; Raja J, Kaushal
2015-01-01
The "gap phenomenon" is an interesting phenomenon in electrophysiology arising from the differences in refractory periods at two or more levels of the atrioventricular (AV) conduction system. We present a patient with dual AV nodal physiology in whom the AH jump mediates the gap phenomenon. We also briefly discuss the other mechanisms of gap phenomenon that have been described in this setting.
Hydraulic Jump and Energy Dissipation with Sluice Gate
Directory of Open Access Journals (Sweden)
Youngkyu Kim
2015-09-01
Full Text Available Movable weirs have been developed to address the weaknesses of conventional fixed weirs. However, the structures for riverbed protection downstream of movable weirs are designed using the criteria of fixed weirs in most cases, and these applications cause problems, such as scour and deformation of structures, due to misunderstanding the difference between different types of structures. In this study, a hydraulic experiment was conducted to examine weir type-specific hydraulic phenomena, compare hydraulic jumps and downstream flow characteristics according to different weir types, and analyze hydraulic characteristics, such as changes in water levels, velocities and energy. Additionally, to control the flow generated by a sluice gate, energy dissipators were examined herein for their effectiveness in relation to different installation locations and heights. As a result, it was found that although sluice gates generated hydraulic jumps similar to those of fixed weirs, their downstream supercritical flow increased to eventually elongate the overall hydraulic jumps. In energy dissipator installation, installation heights were found to be sensitive to energy dissipation. The most effective energy dissipator height was 10% of the downstream free surface water depth in this experiment. Based on these findings, it seems desirable to use energy dissipators to reduce energy, as such dissipators were found to be effective in reducing hydraulic jumps and protecting the riverbed under sluice gates.
Mechanically induced ankle inversion during human walking and jumping.
Nieuwenhuijzen, P.H.J.A.; Grüneberg, C.; Duysens, J.E.J.
2002-01-01
A new method to study sudden ankle inversions during human walking and jumping is presented. Ankle inversions of 25 degrees were elicited using a box containing a trap door. During the gait task, subjects walked at a speed of 4 km/h. At a pre-programmed delay after left heel strike, an electromagnet
Fact or friction: jumps at ultra high frequency
K. Christensen; R. Oomen; M. Podolskij
2011-01-01
In this paper, we demonstrate that jumps in financial asset prices are not nearly as common as generally thought, and that they account for only a very small proportion of total return variation. We base our investigation on an extensive set of ultra high-frequency equity and foreign exchange rate d
Mechanical output in jumps of marmosets (Callithrix jacchus).
Bobbert, Maarten F; Plas, Rogier L C; Weide, Guido; Clairbois, H E Bert; Hofman, Sam O; Jaspers, Richard T; Philippens, Ingrid H C H M
2014-02-15
In this study we determined the mechanical output of common marmosets (Callithrix jacchus) during jumping. Vertical ground reaction forces were measured in 18 animals while they jumped from an instrumented crossbar to a crossbar located 70 cm higher. From the vertical force time histories, we calculated the rate of change of mechanical energy of the centre of mass (dE/dt). The mean value of dE/dt during the push-off amounted to 51.8±6.2 W kg(-1) body mass, and the peak value to 116.4±17.6 W kg(-1) body mass. We used these values in combination with masses of leg muscles, determined in two specimens, to estimate mean and peak values of dE/dt of 430 and 970 W kg(-1) muscle, respectively. These values are higher than values reported in the literature for jumps of humans and bonobos, but smaller than those of jumps of bushbabies. Surprisingly, the mean value of dE/dt of 430 W kg(-1) muscle was close to the maximal power output of 516 W kg(-1) muscle reported in the literature for isokinetic contractions of rat medial gastrocnemius, one of the fastest mammalian muscles. Further study of the force-velocity relationship of muscle tissue of small primates is indicated.
Propulsion efficiency and imposed flow fields of a copepod jump
DEFF Research Database (Denmark)
Jiang, H.; Kiørboe, Thomas
2011-01-01
velocity vectors pointing towards the copepod; such a flow field may inform the predator of the whereabouts of the escaping copepod prey. High Froude propulsion efficiency (0.94–0.98) was obtained for individual power stroke durations of all simulated jumps. This is unusual for small aquatic organisms...
Firms' Overseas Investment Jumps to US$6.9 Billion
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
@@ Foreign investment by domestic firms, excluding banks,jumped 26% last year to US$6.9 billion, the Ministry of Commerce said on February 10. The government has been encouraging domestic companies to head overseas to secure resources, build brands and win market share, and it also welcomes the effect an outflow of investment has on the yuan.
The Missing Luminous Blue Variables and the Bistability Jump
N. Smith; J.S. Vink; A. de Koter
2004-01-01
We discuss an interesting feature of the distribution of luminous blue variables (LBVs) on the H-R diagram, and we propose a connection with the bistability jump seen in the winds of early-type supergiants. There appears to be a deficiency of quiescent LBVs on the S Doradus instability strip at lumi
Asymptotic Behaviour and Extinction of Delay Lotka-Volterra Model with Jump-Diffusion
Dan Li,; Jing’an Cui; Guohua Song
2014-01-01
This paper studies the effect of jump-diffusion random environmental perturbations on the asymptotic behaviour and extinction of Lotka-Volterra population dynamics with delays. The contributions of this paper lie in the following: (a) to consider delay stochastic differential equation with jumps, we introduce a proper initial data space, in which the initial data may be discontinuous function with downward jumps; (b) we show that the delay stochastic differential equation with jumps associate...
Jumping for recognition: Women's ski jumping viewed as a struggle for rights.
Andersen, W; Loland, S
2017-03-01
With the campaign for women's participation in international and Olympic ski jumping as a practical case, sport's potential for recognition of individual rights is explored. In line with Honneth's influential ethical theory, recognition of rights refers to a mutual recognition between persons of each other as rational and responsible agents with an equal right to take part in the public formation and development of their community or practice. The argument is that women ski jumpers were entitled to compete as they had actual and/or potential capabilities and skills to contribute in the public formation and development of their sport. Their exclusion was a violation of individual rights. At a more general level, sport is discussed as a sphere for recognition of rights. It is argued that the basic principles of equal opportunity to take part and to perform make sport a particularly clear and potent sphere for such recognition, and also for the identification of rights violations. In sport, rights, or the violation of rights, are demonstrated in concrete and embodied ways. It is concluded that struggles for recognition and individual rights are a continuous process in sport as in most other human institutions and practices.
Kubelka, Jan
2009-04-01
Many important biochemical processes occur on the time-scales of nanoseconds and microseconds. The introduction of the laser temperature-jump (T-jump) to biophysics more than a decade ago opened these previously inaccessible time regimes up to direct experimental observation. Since then, laser T-jump methodology has evolved into one of the most versatile and generally applicable methods for studying fast biomolecular kinetics. This perspective is a review of the principles and applications of the laser T-jump technique in biophysics. A brief overview of the T-jump relaxation kinetics and the historical development of laser T-jump methodology is presented. The physical principles and practical experimental considerations that are important for the design of the laser T-jump experiments are summarized. These include the Raman conversion for generating heating pulses, considerations of size, duration and uniformity of the temperature jump, as well as potential adverse effects due to photo-acoustic waves, cavitation and thermal lensing, and their elimination. The laser T-jump apparatus developed at the NIH Laboratory of Chemical Physics is described in detail along with a brief survey of other laser T-jump designs in use today. Finally, applications of the laser T-jump in biophysics are reviewed, with an emphasis on the broad range of problems where the laser T-jump methodology has provided important new results and insights into the dynamics of the biomolecular processes.
Neuromuscular adaptations to 4 weeks of intensive drop jump training in well-trained athletes
DEFF Research Database (Denmark)
Alkjær, Tine; Meyland, Jacob; Raffalt, Peter C
2013-01-01
This study examined the effects of 4 weeks of intensive drop jump training in well-trained athletes on jumping performance and underlying changes in biomechanics and neuromuscular adaptations. Nine well-trained athletes at high national competition level within sprinting and jumping disciplines...
Muscle activation history at different vertical jumps and its influence on vertical velocity
Kopper, Bence; Csende, Zsolt; Safar, Sandor; Hortobagyi, Tibor; Tihanyi, Jozsef
In the present study we investigated displacement, time, velocity and acceleration history of center of mass (COM) and electrical activity of knee extensors to estimate the dominance of the factors influencing the vertical velocity in squat jumps (SJs), countermovement jumps (CMJs) and drop jumps
Muscle activation history at different vertical jumps and its influence on vertical velocity
Kopper, Bence; Csende, Zsolt; Safar, Sandor; Hortobagyi, Tibor; Tihanyi, Jozsef
2013-01-01
In the present study we investigated displacement, time, velocity and acceleration history of center of mass (COM) and electrical activity of knee extensors to estimate the dominance of the factors influencing the vertical velocity in squat jumps (SJs), countermovement jumps (CMJs) and drop jumps (D
Psycho-physiological response in an automatic parachute jump.
Clemente-Suárez, Vicente Javier; Robles-Pérez, José Juan; Fernández-Lucas, Jesús
2016-10-11
Parachute jump is an extreme activity that elicits an intense stress response that affects jumpers' body systems being able to put them at risk. The present research analysed modifications in blood oxygen saturation (BOS), heart rate (HR), cortisol, glucose, lactate, creatine kinase (CK), muscles strength, cortical arousal, autonomic modulation, pistol magazine reload time (PMRT) and state anxiety before and after an automatic open parachute jump in 38 male Spanish soldiers (25.6 ± 5.9 years). A MANOVA with samples as a fixed factor and Effect Size (ES) were conducted. MANOVA showed (Wilks lambda = .225; F = 5.980; P = .000) a significantly increase in cortisol (6.2 ± 3.2 vs. 8.2 ± 4.3 nmol/l; P = .025; ES = .47), HR (75.0 ± 14.6 vs. 87.4 ± 17.3 bpm; P = .004; ES = .72), lactate (1.8 ± 1.2 vs. 4.4 ± 2.2 mmol · l(-1); P = .002; ES = 1.18), sympathetic nervous system and leg strength manifestation after the parachute jump. By contrary BOS, PMRT (55.6 ± 27.6 vs. 48.0 ± 16.7 s; P = .021; ES = .46) and somatic anxiety (SA), evaluated by CSAI2R questionnaire, decreased. An automatic parachute jump increased physiological and cortical response and decreased SA of participants. This stress response can affect the jumpers' abilities and allow us to have a better understanding of the organism stress response and to improve training for both military and sport parachute jumps.
Lack of association between postactivation potentiation and subsequent jump performance.
Pearson, Stephen John; Hussain, Syed Robiul
2014-01-01
Postactivation potentiation (PAP) is a strategy that has been used to acutely enhance the performance of explosive activities. Although, isometric maximal voluntary contractions (MVCs) have previously been shown to enhance subsequent explosive performance, no information currently exists regarding (1) the optimal variables (intensity/volume) of a MVC that best elicits a PAP response, and (2) the utilisation of evoked isometric twitch contractions in combination with performance measures to directly ascertain the presence of PAP following a MVC, and its relationship to performance. Thus, the purpose of this study was to (1) investigate the influence of isometric contraction duration on the PAP response, and (2) to determine the relationship between PAP, indicated as potentiation of muscle twitch force and subsequent jump performance following different-duration MVCs. Eight males (age: 21 ± 0.99) were assessed using performance measures [countermovement jumps] and evoked twitch contractions, before and 4 minutes after three different conditioning contractions (CCs), (1) a 3-second MVC (MVC3), (2) a 5-second MVC (MVC5) and (3) a 7-second MVC (MVC7). Following all CCs, peak twitch torque of the knee extensor muscles was found to increase (MVC3, + 3.9%; MVC5, + 9.6%; MVC7, + 5.2%), although not significantly (P > 0.05). No significant increases in jump height, jump power, rate of force development or takeoff velocity were observed following any of the CCs (P > 0.05). There was also a lack of association between the changes in PAP (twitch torque) and jump height following all CCs (MVC3, r = 0.25; MVC5, r = 0.28; MVC7, r = -0.47). These data indicate that PAP as assessed via twitch contractions is not associated with performance measures subsequent to single-set isometric CCs of varying durations.
The kinematics of swimming and relocation jumps in copepod nauplii.
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Christian Marc Andersen Borg
Full Text Available Copepod nauplii move in a world dominated by viscosity. Their swimming-by-jumping propulsion mode, with alternating power and recovery strokes of three pairs of cephalic appendages, is fundamentally different from the way other microplankters move. Protozoans move using cilia or flagella, and copepodites are equipped with highly specialized swimming legs. In some species the nauplius may also propel itself more slowly through the water by beating and rotating the appendages in a different, more complex pattern. We use high-speed video to describe jumping and swimming in nauplii of three species of pelagic copepods: Temora longicornis, Oithona davisae and Acartia tonsa. The kinematics of jumping is similar between the three species. Jumps result in a very erratic translation with no phase of passive coasting and the nauplii move backwards during recovery strokes. This is due to poorly synchronized recovery strokes and a low beat frequency relative to the coasting time scale. For the same reason, the propulsion efficiency of the nauplii is low. Given the universality of the nauplius body plan, it is surprising that they seem to be inefficient when jumping, which is different from the very efficient larger copepodites. A slow-swimming mode is only displayed by T. longicornis. In this mode, beating of the appendages results in the creation of a strong feeding current that is about 10 times faster than the average translation speed of the nauplius. The nauplius is thus essentially hovering when feeding, which results in a higher feeding efficiency than that of a nauplius cruising through the water.
Changes in biomechanical properties during drop jumps of incremental height.
Peng, Hsien-Te
2011-09-01
The purpose of this study was to investigate changing biomechanical properties with increasing drop jump height. Sixteen physically active college students participated in this study and performed drop jumps from heights of 20, 30, 40, 50, and 60 cm (DJ20-DJ60). Kinematic and kinetic data were collected using 11 Eagle cameras and 2 force platforms. Data pertaining to the dominant leg for each of 3 trials for each drop height were recorded and analyzed. Statistical comparisons of vertical ground reaction force (vGRF), impulse, moment, power, work, and stiffness were made between different drop jump heights. The peak vGRF of the dominant leg exceeded 3 times the body weight during DJ50 and DJ60; these values were significantly greater than those for DJ20, DJ30, and DJ40 (all p height jumped during DJ60 was significantly less than that during DJ20 and DJ30 (both p = 0.010). Both the landing impulse and total impulse during the contact phase were significantly different between each drop height (all p height. There were no significant differences in the takeoff impulse. Peak and mean power absorption and negative work at the knee and ankle joints during DJ40, DJ50, and DJ60 were significantly greater than those during DJ20 and DJ30 (all p heights >40 cm offered no advantages in terms of mechanical efficiency (SSC power output) and stiffness. Drop jumps from heights in excess of 60 cm are not recommended because of the lack of biomechanical efficiency and the potentially increased risk of injury.
Keeping your eye on the rail: gaze behaviour of horse riders approaching a jump.
Directory of Open Access Journals (Sweden)
Carol Hall
Full Text Available The gaze behaviour of riders during their approach to a jump was investigated using a mobile eye tracking device (ASL Mobile Eye. The timing, frequency and duration of fixations on the jump and the percentage of time when their point of gaze (POG was located elsewhere were assessed. Fixations were identified when the POG remained on the jump for 100 ms or longer. The jumping skill of experienced but non-elite riders (n = 10 was assessed by means of a questionnaire. Their gaze behaviour was recorded as they completed a course of three identical jumps five times. The speed and timing of the approach was calculated. Gaze behaviour throughout the overall approach and during the last five strides before take-off was assessed following frame-by-frame analyses. Differences in relation to both round and jump number were found. Significantly longer was spent fixated on the jump during round 2, both during the overall approach and during the last five strides (p<0.05. Jump 1 was fixated on significantly earlier and more frequently than jump 2 or 3 (p<0.05. Significantly more errors were made with jump 3 than with jump 1 (p = 0.01 but there was no difference in errors made between rounds. Although no significant correlations between gaze behaviour and skill scores were found, the riders who scored higher for jumping skill tended to fixate on the jump earlier (p = 0.07, when the horse was further from the jump (p = 0.09 and their first fixation on the jump was of a longer duration (p = 0.06. Trials with elite riders are now needed to further identify sport-specific visual skills and their relationship with performance. Visual training should be included in preparation for equestrian sports participation, the positive impact of which has been clearly demonstrated in other sports.
Possibility of stretch-shortening cycle movement training using a jump rope.
Miyaguchi, Kazuyoshi; Sugiura, Hiroki; Demura, Shinichi
2014-03-01
Although jumping rope has been said to be a typical stretch-shortening cycle movement (SSC) from the dynamic analysis of muscle contraction, there are few research reports that focus on this point. Recently, the function of SSC of the legs with respect to the jumping movement has been evaluated using the rebound jump index (RJ-index). This study aimed to examine the possibility of using rope jumping in SSC training by comparing the RJ-index of the rebound jump (standard value) and the 2 different methods of rope jumping. The subjects included 76 healthy young men. Most subjects were involved in routine sports training 2-3 times per week. They performed the rebound jump (5 consecutive vertical jumps) and both a basic and a double-under jump with the jump rope, according to each participant's individual style (rhythm or timing). The RJ-index was calculated using the ground contact time and the jump height. The reliabilities of the RJ-index in the basic (intraclass correlation coefficient: 0.85) and double-under jump (0.92) were high, and the RJ-index of the latter (1.34 ± 0.24) was significantly higher than that of the former (0.60 ± 0.21). In the case of a group with inferior SSC ability, the RJ-index of the rebound jump only showed a significant correlation with the double-under but not with the basic jump. When using the RJ-index (1.97 ± 0.38) of the rebound jump as a criterion, the double-under-using about 70% of the SSC ability-may be effective for reinforcement of SSC ability.
Directory of Open Access Journals (Sweden)
Leonid Serhiyenko
2015-10-01
Full Text Available Purpose: to define the methodology of carrying out the tests: standing high jump and to systematize the general notion about measuring of strength and anaerobic human abilities. Material and Methods: methods of theoretic analysis and generalization, method of search and study of scientific information were used. Results: the standing high jump classification which helps to differentiate jumps according to the way of fulfillment and estimation of the development of motor abilities ware founded. Conclusion: the methodology of doing different kinds of jumps is described
Autonomous Rubidium Clock Weak Frequency Jump Detector for Onboard Navigation Satellite System.
Khare, Akshay; Arora, Rajat; Banik, Alak; Mehta, Sanjay D
2016-02-01
Frequency jumps are common in rubidium frequency sources. They affect the estimation of user position in navigational satellite systems. These jumps must be detected and corrected immediately as they have direct impact on the navigation system integrity. A novel weak frequency jump detector is proposed based on a Kalman filter with a multi-interval approach. This detector can be applied for both "sudden" and "slow" frequency transitions. In this detection method, noises of clock data are reduced by Kalman filtering, for accurate estimation of jump size with less latency. Analysis on in-orbit rubidium atomic frequency standard (RAFS) phase telemetry data shows that the detector can be used for fast detection and correction of weak frequency jumps. Furthermore, performance comparison of different existing frequency jump detection techniques with the proposed detector is discussed. A multialgorithm-based strategy is proposed depending on the jump size and latency for onboard navigation satellites having RAFS as the primary frequency source.
Hotspot Cooling with Self-Propelled Jumping Condensate
Qu, Xiaopeng; Boreyko, Jonathan B.; Liu, Fangjie; Chen, Chuan-Hua
2012-11-01
Dynamic hotspots are prevalent in electronic systems including microprocessors and power electronics with constantly changing computing tasks or payloads. Here, we report a new adaptive hotspot cooling technique that rapidly responds to moving hotspots in a passive manner independent of external forces. The hotspot cooling is based upon the self-propelled jumping of dropwise condensate, which directly returns the working fluid from a superhydrophobic condenser to an opposing superhydrophilic evaporator. The adaptive thermal management is accomplished by the preferential evaporation of water at the hotspots and the rapid jumping return of the condensate across the very short inter-plate distance. The proof-of-concept for this hotspot cooling technique will be demonstrated by the adaptive response to hotspots at increasing heat fluxes. Corresponding author.
VaR: Exchange Rate Risk and Jump Risk
Directory of Open Access Journals (Sweden)
Fen-Ying Chen
2010-01-01
Full Text Available Incorporating the Poisson jumps and exchange rate risk, this paper provides an analytical VaR to manage market risk of international portfolios over the subprime mortgage crisis. There are some properties in the model. First, different from past studies in portfolios valued only in one currency, this model considers portfolios not only with jumps but also with exchange rate risk, that is vital for investors in highly integrated global financial markets. Second, in general, the analytical VaR solution is more accurate than historical simulations in terms of backtesting and Christoffersen's independence test (1998 for small portfolios and large portfolios. In other words, the proposed model is reliable not only for a portfolio on specific stocks but also for a large portfolio. Third, the model can be regarded as the extension of that of Kupiec (1999 and Chen and Liao (2009.
Control and filtering for semi-Markovian jump systems
Li, Fanbiao; Wu, Ligang
2017-01-01
This book presents up-to-date research developments and novel methodologies on semi-Markovian jump systems (S-MJS). It presents solutions to a series of problems with new approaches for the control and filtering of S-MJS, including stability analysis, sliding mode control, dynamic output feedback control, robust filter design, and fault detection. A set of newly developed techniques such as piecewise analysis method, positively invariant set approach, event-triggered method, and cone complementary linearization approaches are presented. Control and Filtering for Semi-Markovian Jump Systems is a comprehensive reference for researcher and practitioners working in control engineering, system sciences and applied mathematics, and is also a useful source of information for senior undergraduates and graduates in these areas. The readers will benefit from some new concepts, new models and new methodologies with practical significance in control engineering and signal processing.
Pricing Asian power options under jump-fraction process
Directory of Open Access Journals (Sweden)
Bin Peng
2012-12-01
Full Text Available A framework for pricing Asian power options is developed when the underlying asset follows a jump-fraction process. The partial differential equation (PDE in the fractional environment with jump is constructed for such option using general Itô's lemma and self-financing dynamic strategy. With the boundary condition, an analytic formula for the option with geometric average starting at any time before maturity is derived by solving the PDE, and the option with arithmetic average is evaluated in Monte Carlo simulation using control variate technique with the help of the above analytic solution. Overwhelming numerical evidence indicates that the technique proposed is computationally efficient and dramatically improves the accuracy of the simulated price. Moreover, this study will pave a novel way to copy with the option contracts based on thinly-traded assets like oil, or currencies or interest rates.
The circular jump as a hydrodynamic white hole
Jannes, Gil
2012-01-01
Surface waves in classical fluids experience a rich array of black/white hole horizon effects. The dispersion relation depends on the characteristics of the fluid as well as on the fluid depth and the wavelength regime. We focus on the shallow-water regime, and discuss the experimental proof that the circular hydraulic jump marks the transition between a supercritical and a subcritical flow regime. This finally confirms a theoretical conjecture formulated by Lord Rayleigh nearly 100 years ago. It also confirms that the circular jump corresponds to the spontaneous formation of a hydrodynamic white hole, with interesting characteristics from the point of view of analogue gravity. We study the dispersive regime, mention some lessons about the trans-Planckian issue and describe possible directions for future work.
The asteroid belt outer region under jumping-Jupiter migration
Gaspar, H. S.; Winter, O. C.; Vieira Neto, E.
2017-09-01
The radial configuration of the outer region of the main asteroid belt is quite peculiar, and has much to say about the past evolution of Jupiter. In this work, we investigate the dynamical effects of a jumping-Jupiter-like migration over a more extended primordial asteroid belt. Jupiter's migrations are simulated using a fast jumping-Jupiter synthesizer. Among the results, we highlight non-negligible fractions of primordial objects trapped in 3:2 and 4:3 mean motion resonances (MMRs) with Jupiter. They survived the whole truculent phase of migration and originated populations that are like Hildas and Thules. Fractions ranging from 3 to 6 per cent of the initial distribution remained trapped in 3:2 MMR, and at least 0.05 per cent in 4:3. These results show that the resonance trapping of primordial objects may have originated these resonant populations. This theory is consistent even for Jupiter's truculent evolution.
Characteristics of a hydraulic jump in Bingham fluid
Shu, Jian-Jun
2014-01-01
In this paper, we seek an adequate macroscopic model for a hydraulic jump in Bingham fluid. The formulas for conjugate depths, sequent bottom shear stress and critical depth are established. Since no exact analytical solution in closed form is available for conjugate depths, an approximate formula is developed. This formula can provide good results with an error less than 4%. The analytical results have revealed that the critical depth and the ratio of conjugate depths increase until bottom shear stress exceeds a certain value and then decrease afterwards. The bottom shear stress downstream of the jump is smaller than that upstream. The results are verified by experimental data and observations available in the literature.
A characterization of oil price behavior. Evidence from jump models
Energy Technology Data Exchange (ETDEWEB)
Gronwald, Marc [Munich Univ. (Germany). Ifo Institute - Leibniz Institute for Economic Research
2011-11-15
This paper is concerned with the statistical behavior of oil prices in two ways. It, firstly, applies a combined jump GARCH in order to characterize the behavior of daily, weekly as well as monthly oil prices. Secondly, it relates its empirical results to implications of Hotelling-type resource extraction models. The empirical analysis shows that oil prices are characterized by GARCH as well as conditional jump behavior and that a considerable portion of the total variance is triggered by sudden extreme price movements. This finding implies that, first, oil price signals are not reliable and, as a consequence, both finding optimal extraction paths and decisions regarding the transmission to alternative technologies are likely to be compromised. Second, this behavior is in stark contrast to the notion of deterministic trends in the price of oil. (orig.)
Forecasting Exchange Rate Volatility in the Presence of Jumps
DEFF Research Database (Denmark)
Busch, Thomas; Christensen, Bent Jesper; Nielsen, Morten Ørregaard
of exchange rate futures options, allowingcalculation of option implied volatility. We find that implied volatility is an informationallyeﬃcient but biased forecast of future realized exchange rate volatility. Furthermore,we show that log-normality is an even better distributional approximation...... for impliedvolatility than for realized volatility in this market. Finally, we show that the jump componentof future realized exchange rate volatility is to some extent predictable, and thatoption implied volatility is the dominant forecast of the future jump component.......We study measures of foreign exchange rate volatility based on high-frequency (5-minute) $/DM exchange rate returns using recent nonparametric statistical techniquesto compute realized return volatility and its separate continuous sample path and jumpcomponents, and measures based on prices...
Frequency jumps in single chip microwave LC oscillators
Energy Technology Data Exchange (ETDEWEB)
Gualco, Gabriele; Grisi, Marco; Boero, Giovanni, E-mail: giovanni.boero@epfl.ch [Ecole Polytechnique Fédérale de Lausanne (EPFL), Lausanne CH-1015 (Switzerland)
2014-12-15
We report on the experimental observation of oscillation frequency jumps in microwave LC oscillators fabricated using standard complementary metal-oxide-semiconductor technologies. The LC oscillators, operating at a frequency of about 20 GHz, consist of a single turn planar coil, a metal-oxide-metal capacitor, and two cross-coupled metal-oxide-semiconductor field effect transistors used as negative resistance network. At 300 K as well as at 77 K, the oscillation frequency is a continuous function of the oscillator bias voltage. At 4 K, frequency jumps as large as 30 MHz are experimentally observed. This behavior is tentatively attributed to the emission and capture of single electrons from defects and dopant atoms.
BIOMECHANICAL ANALYSIS OF RUNNING IN THE HIGH JUMP
Directory of Open Access Journals (Sweden)
Leite Werlayne
2013-02-01
Full Text Available The aim of this paper is to analyze the biomechanics of running at high jump. To this study was realized a bibliographic revision. The running phase is the one which starts when the athlete is set in movement for the jump until the moment that he touches the ground with the takeoff foot in front of the bar, this phase can be divided into two parts: the running in straight line and the running in curve. On the other hand, for better understanding and due to a biomechanical complexity, the running in curve will be divided into three other parts: the three last strides, the two last strides and the last strides. Besides that, we could mention important factors for an efficient approach run: the radius of the curve, the distance and length of the takeoff run.
Option Pricing with Stochastic Volatility and Jump Diffusion Processes
Directory of Open Access Journals (Sweden)
Radu Lupu
2006-05-01
Full Text Available Option pricing by the use of Black Scholes Merton (BSM model is based on the assumption that asset prices have a lognormal distribution. In spite of the use of these models on a large scale, both by practioners and academics, the assumption of lognormality is rejected by the history of returns. The objective of this article is to present the methods that developed after the Black Scholes Merton environment and deals with the option pricing model adjustment to the empirical properties of asset returns. The main models that appeared after BSM allowed for special changes of the returns that materialized in jump-diffusion and stochastic volatility processes. The article presents the foundations of risk neutral options evaluation and the empirical evidence that fed the amendment of the lognormal assumption in the first part and shows the evaluation procedure under the assumption of stock prices following the jump-diffusion process and the stochastic volatility process.
Option Pricing with Stochastic Volatility and Jump Diffusion Processes
Directory of Open Access Journals (Sweden)
Radu Lupu
2006-03-01
Full Text Available Option pricing by the use of Black Scholes Merton (BSM model is based on the assumption that asset prices have a lognormal distribution. In spite of the use of these models on a large scale, both by practioners and academics, the assumption of lognormality is rejected by the history of returns. The objective of this article is to present the methods that developed after the Black Scholes Merton environment and deals with the option pricing model adjustment to the empirical properties of asset returns. The main models that appeared after BSM allowed for special changes of the returns that materialized in jump-diffusion and stochastic volatility processes. The article presents the foundations of risk neutral options evaluation and the empirical evidence that fed the amendment of the lognormal assumption in the first part and shows the evaluation procedure under the assumption of stock prices following the jump-diffusion process and the stochastic volatility process.
[Continuous electrocardiographic recording during a first parachute jump].
Galante, J; Hernández, A; Colín, L; Camacho, B; Verdejo, J; Férez, S
1988-01-01
The behavior of the cardiac rhythm under intense stress was studied with continuous electrocardiographic recording during the first jump with an automatic parachute in 13 members of the Universidad Nacional Autónoma de México sky diving club. There were 12 male (92.3%) and one female (7.68) with an average age of 22.8 years. A complete clinical history, 12 lead electrocardiogram and a treadmill stress test were performed two weeks before jumping. A two-channel Holter recording system was hooked up 30 min. before boarding the airplane and was turned off one hour later. The heart rate values were compared two weeks prior (64.5 beats/min), before (112.8 beats/min), during (170 beats/min) and after the jump (122.8 beats/min). The mean difference between each phase was statistically significant with p less than 0.001 values. The observed cardiac rhythm was sinus tachycardia in each case. In six cases (43.6%) 22 episodes of sudden decrease of the heart rate were seen and there were no major rhythm or conduction disturbances. The urinary catecholamines were similar in nine cases (69.2%) after the jump (x 51.2 micrograms/100 ml) and two weeks later in four control cases (x 10.3 micrograms/100 ml). We concluded there were no significant rhythm disturbances in the presence of an intense but brief stress condition in young healthy people. This study was classified as longitudinally, descriptive, experimental and projective.
LINEAR QUADRATIC NONZERO-SUM DIFFERENTIAL GAMES WITH RANDOM JUMPS
Institute of Scientific and Technical Information of China (English)
WU Zhen; YU Zhi-yong
2005-01-01
The existence and uniqueness of the solutions for one kind of forwardbackward stochastic differential equations with Brownian motion and Poisson process as the noise source were given under the monotone conditions. Then these results were applied to nonzero-sum differential games with random jumps to get the explicit form of the open-loop Nash equilibrium point by the solution of the forward-backward stochastic differential equations.
Asymptotic Expansions of Transition Densities for Hybrid Jump-Diffusions
Institute of Scientific and Technical Information of China (English)
Yuan-jin Liu; G.Yin
2004-01-01
A class of hybrid jump diffusions modulated by a Markov chain is considered in this work.The motivation stems from insurance risk models,and emerging applications in production planning and wireless communications.The models are hybrid in that they involve both continuous dynamics and discrete events.Under suitable conditions,asymptotic expansions of the transition densities for the underlying processes are developed.The formal expansions are validated and the error bounds obtained.
The beginning of time observed in quantum jumps
Energy Technology Data Exchange (ETDEWEB)
Bohm, Arno [CCQS, Physics Department, University of Texas, Austin, TX (United States); Bryant, Peter W. [IBM Research, Rio de Janeiro (Brazil); Uncu, Haydar [Department of Physics, Adnan Menderes University, Aydin (Turkey); Wickramasekara, Sujeev [Department of Physics, Grinnell College, Grinnell, IA (United States); Schleich, Wolfgang P. [Institut fuer Quantenphysik and Center for Integrated Quantum Science and Technology, Universitaet Ulm (Germany); Hagler Institute for Advanced Study, Texas A and M University, College Station, TX (United States); Texas A and M AgriLife, Institute for Quantum Science and Engineering (IQSE) and Department of Physics and Astronomy, Texas A and M University, College Station, TX (United States)
2017-06-15
The phenomenon of quantum jumps observed in a single ion stored in a trap brings to light intimate connections between three different concepts of quantum physics: (i) quantum state trajectories, (ii) Gamow states, and (iii) the arrow of time. In particular, it allows us to identify the starting time of the semigroup time evolution. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)
The Economics of Bitcoins - Market Characteristics and Price Jumps
Gronwald, Marc
2014-01-01
This paper deals with the economics of Bitcoins in two ways. First, it broadens the discussion on how to capture Bitcoins using economic terms. Center stage in this analysis take the discussion of some unique characteristics of this market as well as the comparison of Bitcoins and gold. Second, the paper empirically analyses Bitcoin prices using an autoregressive jump-intensity GARCH model; a model tested and proven by the empirical finance community. Results suggest that Bitcoin price are pa...
The Effects of Arms and Countermovement on Vertical Jumping
1989-04-28
result from potcntiation, during the oertilc stretching phase, of myoelectric activity during the subsequent concentric contraction phase. However...The output signal representing vertical ground reaction force (VGRF) was fed into a Hewlett-Packard (Lexington MA) 310 microcomputer via an Infotek...BOSCO, C., and J.T. VIITASALO. Potentiation of myoelectric activity of human muscles in vertical jumps. Electromyogr clin Neurophysiol 22:549-562, 1982
Diversified Portfolios with Jumps in a Benchmark Framework
Eckhard Platen
2004-01-01
This paper considers diversifed portfolios in a sequence of jump diffusion market models. Conditions for the approximation of the growth optimal portfolio (GOP) by diversified portfolios are provided. Under realistic assumptions, it is shown that diversified portfolios approximate the GOP without requiring any major model specifications. This provides a basis for systematic use of diversified stock indices as proxies for the GOP in derivative pricing, risk management and portfolio optimization.
Anticipating Viral Species Jumps: Bioinformatics and Data Needs
2011-06-01
and colleagues are currently adding SF for dengue, hepatitis C and pox viruses by manually searching the literature; in the future they will begin...2008). Hendra viruses from Australian fruit bats have caused small , isolated fatal disease outbreaks among horses and fatal spillover cases among...species jump to humans. They and others (Pepin et al. 2010) point out that the available sample size is too small to draw conclusions about the
Incomplete Financial Markets and Jumps in Asset Prices
DEFF Research Database (Denmark)
Crès, Hervé; Markeprand, Tobias Ejnar; Tvede, Mich
A dynamic pure-exchange general equilibrium model with uncertainty is studied. Fundamentals are supposed to depend continuously on states of nature. It is shown that: 1. if financial markets are complete, then asset prices vary continuously with states of nature, and; 2. if financial markets...... are incomplete, jumps in asset prices may be unavoidable. Consequently incomplete financial markets may increase volatility in asset prices significantly....
Soap film dynamics and topological jumps under continuous deformation
Moffatt, Keith
2015-11-01
Consider the dynamics of a soap-film bounded by a flexible wire (or wires) which can be continuously and slowly deformed. At each instant the soap-film relaxes in quasi-static manner to a minimum-area (i.e. minimum-energy) state compatible with the boundary configuration. This can however pass through a critical configuration at which a topological jump is inevitable. We have studied an interesting example of this behaviour: the jump of a one-sided (Möbius strip) soap-film to a two-sided film as the boundary is unfolded and untwisted from the double cover of a circle. The nature of this jump will be demonstrated and explained. More generally, dynamical systems have a natural tendency to relax through dissipative processes to a minimum-energy state, subject to any relevant constraints. An example is provided by the relaxation of a magnetic field in a perfectly conducting but viscous fluid, subject to the constraint that the magnetic field lines are frozen in the fluid. One may infer the existence of magnetostatic equilibria (and analogous steady Euler flows) of arbitrary field-line topology. In general, discontinuities (current sheets) appear during this relaxation process, and this is where reconnection of field-lines (with associated change of topology) can occur. Just as for the soap film, slow change of boundary conditions can lead to critical conditions in which such topological jumps are inevitable. (Work in collaboration with Ray Goldstein, Adriana Pesci, Renzo Ricca and Gareth Alexander.) This work was supported by Engineering and Physical Sciences Research Council Grant EP/I036060/1.
Shock jump relations for a dusty gas atmosphere
Anand, R. K.
2014-01-01
This paper presents simplified forms of jump relations for one dimensional shock waves propagating in a dusty gas. The dusty gas is assumed to be a mixture of a perfect gas and spherically small solid particles, in which solid particles are continuously distributed. The simplified jump relations for the pressure, the temperature, the density, the velocity of the mixture and the speed of sound have been derived in terms of the upstream Mach number. The expressions for the adiabatic compressibility of the mixture and the change-in-entropy across the shock front have also been derived in terms of the upstream Mach number. Further, the handy forms of shock jump relations have been obtained in terms of the initial volume fraction of small solid particles and the ratio of specific heats of the mixture, simultaneously for the two cases viz., (i) when the shock is weak and, (ii) when it is strong. The simplified shock jump relations reduce to the Rankine-Hugoniot conditions for shock waves in an ideal gas when the mass fraction (concentration) of solid particles in the mixture becomes zero. Finally, the effects due to the mass fraction of solid particles in the mixture, and the ratio of the density of solid particles to the initial density of the gas are studied on the pressure, the temperature, the density, the velocity of the mixture, the speed of sound, the adiabatic compressibility of the mixture and the change-in-entropy across the shock front. The results provided a clear picture of whether and how the presence of dust particles affects the flow field behind the shock front. The aim of this paper is to contribute to the understanding of how the shock waves behave in the gas-solid particle two-phase flows.
Forecasting Exchange Rate Volatility in the Presence of Jumps
Busch, Thomas; Christensen, Bent Jesper; Nielsen, Morten Ørregaard
2005-01-01
We study measures of foreign exchange rate volatility based on high-frequency (5-minute) $/DM exchange rate returns using recent nonparametric statistical techniques to compute realized return volatility and its separate continuous sample path and jump components, and measures based on prices of exchange rate futures options, allowing calculation of option implied volatility. We find that implied volatility is an informationally efficient but biased forecast of future realized exchange rate v...
Stabilization of stochastic systems with hidden Markovian jumps
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper considers the adaptive control of discrete-time hybrid stochastic systems with unknown randomly jumping parameters described by a finite-state hidden Markov chain. An intuitive yet longstanding conjecture in this area is that such hybrid systems can be adaptively stabilized whenever the rate of transition of the hidden Markov chain is small enough. This paper provides a rigorous positive answer to this conjecture by establishing the global stability of a gradient-algorithm-based adaptive linear-quadratic control.
LOAD THAT MAXIMIZES POWER OUTPUT IN COUNTERMOVEMENT JUMP
Directory of Open Access Journals (Sweden)
Pedro Jimenez-Reyes
2016-02-01
Full Text Available ABSTRACT Introduction: One of the main problems faced by strength and conditioning coaches is the issue of how to objectively quantify and monitor the actual training load undertaken by athletes in order to maximize performance. It is well known that performance of explosive sports activities is largely determined by mechanical power. Objective: This study analysed the height at which maximal power output is generated and the corresponding load with which is achieved in a group of male-trained track and field athletes in the test of countermovement jump (CMJ with extra loads (CMJEL. Methods: Fifty national level male athletes in sprinting and jumping performed a CMJ test with increasing loads up to a height of 16 cm. The relative load that maximized the mechanical power output (Pmax was determined using a force platform and lineal encoder synchronization and estimating the power by peak power, average power and flight time in CMJ. Results: The load at which the power output no longer existed was at a height of 19.9 ± 2.35, referring to a 99.1 ± 1% of the maximum power output. The load that maximizes power output in all cases has been the load with which an athlete jump a height of approximately 20 cm. Conclusion: These results highlight the importance of considering the height achieved in CMJ with extra load instead of power because maximum power is always attained with the same height. We advise for the preferential use of the height achieved in CMJEL test, since it seems to be a valid indicative of an individual's actual neuromuscular potential providing a valid information for coaches and trainers when assessing the performance status of our athletes and to quantify and monitor training loads, measuring only the height of the jump in the exercise of CMJEL.
Aerodynamics of ski jumping flight and its control: II. Simulations
Lee, Jungil; Lee, Hansol; Kim, Woojin; Choi, Haecheon
2015-11-01
In a ski jumping competition, it is essential to analyze the effect of various posture parameters of a ski jumper to achieve a longer flight distance. For this purpose, we conduct a large eddy simulation (LES) of turbulent flow past a model ski jumper which is obtained by 3D scanning a ski jumper's body (Mr. Chil-Ku Kang, member of the Korean national team). The angle of attack of the jump ski is 30° and the Reynolds number based on the length of the jump ski is 540,000. The flow statistics including the drag and lift coefficients in flight are in good agreements with our own experimental data. We investigate the flow characteristics such as the flow separation and three-dimensional vortical structures and their effects on the drag and lift. In addition to LES, we construct a simple geometric model of a ski jumper where each part of the ski jumper is modeled as a canonical bluff body such as the sphere, cylinder and flat plate, to find its optimal posture. The results from this approach will be compared with those by LES and discussed. Supported by NRF program (2014M3C1B1033848, 2014R1A1A1002671).
Kinematic Chains in Ski Jumping In-run Posture.
Janurová, Eva; Janura, Miroslav; Cabell, Lee; Svoboda, Zdeněk; Vařeka, Ivan; Elfmark, Milan
2013-12-18
The concept of kinematic chains has been systematically applied to biological systems since the 1950s. The course of a ski jump can be characterized as a change between closed and open kinematic chains. The purpose of this study was to determine a relationship between adjacent segments within the ski jumper's body's kinematic chain during the in-run phase of the ski jump. The in-run positions of 267 elite male ski jumpers who participated in the FIS World Cup events in Innsbruck, Austria, between 1992 and 2001 were analyzed (656 jumps). Two-dimensional (2-D) kinematic data were collected from the bodies of the subjects. Relationships between adjacent segments of the kinematic chain in the ski jumper's body at the in-run position are greater nearer the chain's ground contact. The coefficient of determination between the ankle and knee joint angles is 0.67. Changes in the segments' positions in the kinematic chain of the ski jumper's body are stable during longitudinal assessment. Changes in shank and thigh positions, in the sense of increase or decrease, are the same.
Bubble entrainment, spray and splashing at hydraulic jumps
Institute of Scientific and Technical Information of China (English)
CHANSON Hubert
2006-01-01
The sudden transition from a high-velocity, supercritical open channel flow into a slow-moving sub-critical flow is a hydraulic jump. Such a flow is characterised by a sudden rise of the free-surface, with some strong energy dissipation and air entrainment, waves and spray. New two-phase flow measurements were performed in the developing flow region using a large-size facility operating at large Reynolds numbers. The experimental results demonstrated the complexity of the flow with a developing mixing layer in which entrained bubbles are advected in a high shear stress flow. The relationship between bubble count rates and void fractions was non-unique in the shear zone, supporting earlier observations of some form of double diffusion process between momentum and air bubbles. In the upper region, the flow consisted primarily of water drops and packets surrounded by air. Visually significant pray and splashing were significant above the jump roller. The present study is the first comprehensive study detailing the two-phase flow properties of both the bubbly and spray regions of hydraulic jumps, a first step towards understanding the interactions between bubble entrainment and droplet ejection processes.
Overcoming horizontal depolarizing resonances with multiple tune jumps
Huang, H.; Ahrens, L. A.; Bai, M.; Brown, K. A.; Dutheil, Y.; Gardner, C.; Glenn, J. W.; Lin, F.; MacKay, W. W.; Meot, F.; Poblaguev, A.; Ranjbar, V.; Roser, T.; Schoefer, V.; Tepikian, S.; Tsoupas, N.; Yip, K.; Zelenski, A.; Zeno, K.
2014-08-01
In a medium energy proton synchrotron, strong enough partial Siberian snakes can be used to avoid both imperfection and vertical intrinsic depolarizing resonances. However, partial snakes tilt the stable spin direction away from vertical, which generates depolarizing resonances associated with horizontal tune. The relatively weak but numerous horizontal intrinsic resonances are the main source of the residual polarization losses. A pair of horizontal tune jump quads have been used in the Brookhaven Alternating Gradient Synchrotron to overcome these weak resonances. The locations of the two quads have to be chosen such that the disturbance to the beam optics is minimum. The emittance growth has to be mitigated for this method to work. In addition, this technique needs very accurate jump timing. Using two partial Siberian snakes, with vertical tune inside the spin tune gap and 80% polarization at the Alternating Gradient Synchrotron injection, polarized proton beam had reached 1.5×1011 proton per bunch with 65% polarization. With the tune jump timing optimized and emittance preserved, more than 70% polarization with 2×1011 protons per bunch has been achieved. The polarization transport efficiency is close to 90%.
Jump dynamics with structural breaks for crude oil prices
Energy Technology Data Exchange (ETDEWEB)
Lee, Yen-Hsien [Department of Finance, Chung Yuan Christian University (China); Hu, Hsu-Ning [Department of Money, Banking and Finance, TamKang University (China); Chiou, Jer-Shiou [Department of Finance and Banking, Shih Chien University, 70 Ta-Chih Street, Taipei 104 (China)
2010-03-15
This study investigates the joint phenomena of permanent and transitory components in conditional variance and jump intensity along with verification of structural breaks for crude oil prices. We adopt a Component-ARJI model with structural break analysis, utilizing daily data on West Texas Intermediate crude oil spot and futures contracts. The analytical results verify the existence of permanent and transitory components in conditional variance, with the permanent component of conditional variance increasing with the occurrence of a sudden major event (such as the Iraqi Invasion of Kuwait, Operation Desert Storm and the war between the US and Iraq), and a relatively greater increase in the transitory component over the same period. Notably, jump intensity fluctuates with an increase in the transitory component of conditional variance in response to abnormal events. It is the transitory component which serves as the primary influential factor for jumps in returns; therefore, speculators are willing to take large risks, particularly with respect to anticipating future price movements, or gambling, in the hopes of rapidly making substantial gains; thus, speculators prefer the temporary volatility component and engage in trade activities. However, investors prefer the permanent volatility component, because they may well be better off relocating their assets into more stable portfolios to outperform the market portfolio over the long run. (author)
JUMP LANDING CHARACTERISTICS IN ELITE SOCCER PLAYERS WITH CEREBRAL PALSY
Directory of Open Access Journals (Sweden)
Jesús Cámara
2013-04-01
Full Text Available The aim of the present study was to analyse the parameters that characterize the vertical ground reaction force during the landing phase of a jump, and to determine the relationship among these parameters in elite soccer players with cerebral palsy (CP. Thirteen male members of the Spanish national soccer team for people with CP (mean age: 27.1 ± 4.7 years volunteered for the study. Each participant performed three counter movement jumps. The characteristics of the first peak of the vertical ground reaction force during the landing phase of a jump, which corresponds to the forefoot contact with the ground, were similar to the results obtained in previous studies. However, a higher magnitude of rearfoot contact with the ground (F2 was observed in participants with CP than in participants without CP. Furthermore, a significant correlation between F2 magnitude and the elapsed time until its production (T2 was not observed (r = -0.474 for p = 0.102. This result implies that a landing technique based on a delay in the production of F2 might not be effective to reduce its magnitude, contrary to what has been observed in participants without CP. The absence of a significant correlation between these two parameters in the present study, and the high magnitude of F2, suggest that elite soccer players with CP should use footwear with proper cushioning characteristics.
Overcoming horizontal depolarizing resonances with multiple tune jumps
Directory of Open Access Journals (Sweden)
H. Huang
2014-08-01
Full Text Available In a medium energy proton synchrotron, strong enough partial Siberian snakes can be used to avoid both imperfection and vertical intrinsic depolarizing resonances. However, partial snakes tilt the stable spin direction away from vertical, which generates depolarizing resonances associated with horizontal tune. The relatively weak but numerous horizontal intrinsic resonances are the main source of the residual polarization losses. A pair of horizontal tune jump quads have been used in the Brookhaven Alternating Gradient Synchrotron to overcome these weak resonances. The locations of the two quads have to be chosen such that the disturbance to the beam optics is minimum. The emittance growth has to be mitigated for this method to work. In addition, this technique needs very accurate jump timing. Using two partial Siberian snakes, with vertical tune inside the spin tune gap and 80% polarization at the Alternating Gradient Synchrotron injection, polarized proton beam had reached 1.5×10^{11} proton per bunch with 65% polarization. With the tune jump timing optimized and emittance preserved, more than 70% polarization with 2×10^{11} protons per bunch has been achieved. The polarization transport efficiency is close to 90%.
The kinematics of swimming and relocation jumps in copepod nauplii
DEFF Research Database (Denmark)
Borg, Marc Andersen; Bruno, Eleonora; Kiørboe, Thomas
2012-01-01
Copepod nauplii move in a world dominated by viscosity. Their swimming-by-jumping propulsion mode, with alternating power and recovery strokes of three pairs of cephalic appendages, is fundamentally different from the way other microplankters move. Protozoans move using cilia or flagella, and cop......Copepod nauplii move in a world dominated by viscosity. Their swimming-by-jumping propulsion mode, with alternating power and recovery strokes of three pairs of cephalic appendages, is fundamentally different from the way other microplankters move. Protozoans move using cilia or flagella......, and copepodites are equipped with highly specialized swimming legs. In some species the nauplius may also propel itself more slowly through the water by beating and rotating the appendages in a different, more complex pattern. We use high-speed video to describe jumping and swimming in nauplii of three species...... larger copepodites. A slow-swimming mode is only displayed by T. longicornis. In this mode, beating of the appendages results in the creation of a strong feeding current that is about 10 times faster than the average translation speed of the nauplius. The nauplius is thus essentially hovering when...
NONINVASIVE DETERMINATION OF KNEE CARTILAGE DEFORMATION DURING JUMPING
Directory of Open Access Journals (Sweden)
Djordje Kosanic
2009-12-01
Full Text Available The purpose of this investigation was to use a combination of image processing, force measurements and finite element modeling to calculate deformation of the knee cartilage during jumping. Professional athletes performed jumps analyzed using a force plate and high-speed video camera system. Image processing was performed on each frame of video using a color recognition algorithm. A simplified mass-spring-damper model was utilized for determination of global force and moment on the knee. Custom software for fitting the coupling characteristics was created. Simulated results were used as input data for the finite element calculation of cartilage deformation in the athlete's knee. Computer simulation data was compared with the average experimental ground reaction forces. The results show the three-dimensional mechanical deformation distribution inside the cartilage volume. A combination of the image recognition technology, force plate measurements and the finite element cartilage deformation in the knee may be used in the future as an effective noninvasive tool for prediction of injury during jumping
Chabanenko, V. V.; Rusakov, V. F.; D'yachenko, A. I.; Piechota, S.; Nabialek, A.; Szymczak, H.
2000-11-01
Magnetic properties of superconductors with peak effect were investigated both experimentally and theoretically in frames of the critical state model which incorporates the flux jump instability criterion. Theoretical analyses show some “forbidden” band for flux jumps on the magnetic field axis. Features of H-T diagrams of instability of superconductors with peak effect are discussed.
Dynamical approach to displacement jumps in nanoindentation experiments
K, Srikanth; Ananthakrishna, G.
2017-01-01
The load-controlled mode is routinely used in nanoindentation experiments. Yet there are no simulations or models that predict the generic features of force-displacement F -z curves, in particular, the existence of several displacement jumps of decreasing magnitude. Here, we show that the recently developed dislocation dynamical model predicts all the generic features when the model is appropriately coupled to an equation defining the load rate. Since jumps in the indentation depth result from the plastic deformation occurring inside the sample, we devise a method for calculating this contribution by setting up a system of coupled nonlinear time evolution equations for the mobile and forest dislocation densities. The equations are then coupled to the force rate equation. We include nucleation, multiplication, and propagation threshold mechanisms for the mobile dislocations apart from other well known dislocation transformation mechanisms between the mobile and forest dislocations. The commonly used Berkovitch indenter is considered. The ability of the approach is illustrated by adopting experimental parameters such as the indentation rate, the geometrical quantities defining the Berkovitch indenter including the nominal tip radius, and other parameters. We identify specific dislocation mechanisms contributing to different regions of the F -z curve as a first step for obtaining a good fit to a given experimental F -z curve. This is done by studying the influence of the parameters on the model F -z curves. In addition, the study demonstrates that the model predicts all the generic features of nanoindentation such as the existence of an initial elastic branch followed by several displacement jumps of decreasing magnitude, and residual plasticity after unloading for a range of model parameter values. Further, an optimized set of parameter values can be easily determined that gives a good fit to the experimental force-displacement curve for Al single crystals of (110
Ashley-Ross, Miriam A; Perlman, Benjamin M; Gibb, Alice C; Long, John H
2014-02-01
Despite having no obvious anatomical modifications to facilitate movement over land, numerous small fishes from divergent teleost lineages make brief, voluntary terrestrial forays to escape poor aquatic conditions or to pursue terrestrial prey. Once stranded, these fishes produce a coordinated and effective "tail-flip" jumping behavior, wherein lateral flexion of the axial body into a C-shape, followed by contralateral flexion of the body axis, propels the fish into a ballistic flight-path that covers a distance of multiple body lengths. We ask: how do anatomical structures that evolved in one habitat generate effective movement in a novel habitat? Within this context, we hypothesized that the mechanical properties of the axial skeleton play a critical role in producing effective overland movement, and that tail-flip jumping species demonstrate enhanced elastic energy storage through increased body flexural stiffness or increased body curvature, relative to non-jumping species. To test this hypothesis, we derived a model to predict elastic recoil work from the morphology of the vertebral (neural and hemal) spines. From ground reaction force (GRF) measurements and high-speed video, we calculated elastic recoil work, flexural stiffness, and apparent material stiffness of the body for Micropterus salmoides (a non-jumper) and Kryptolebias marmoratus (adept tail-flip jumper). The model predicted no difference between the two species in work stored by the vertebral spines, and GRF data showed that they produce the same magnitude of mass-specific elastic recoil work. Surprisingly, non-jumper M. salmoides has a stiffer body than tail-flip jumper K. marmoratus. Many tail-flip jumping species possess enlarged, fused hypural bones that support the caudal peduncle, which suggests that the localized structures, rather than the entire axial skeleton, may explain differences in terrestrial performance.
Research on one Bio-inspired Jumping Locomotion Robot for Search and Rescue
Directory of Open Access Journals (Sweden)
Dunwen Wei
2014-10-01
Full Text Available Jumping locomotion is much more effective than other locomotion means in order to tackle the unstructured and complex environment in research and rescue. Here, a bio-inspired jumping robot with a closed-chain mechanism is proposed to achieve the power amplification during taking-off. Through actuating one variable transmission mechanism to change the transmission ratio, the jumping robot reveals biological characteristics in the phase of posture adjustment when adjusting the height and distance of one jump. The kinematics and dynamics of the simplified jumping mechanism model in one jumping cycle sequence are analysed. A compliant contact model considering nonlinear damping is investigated for jumping performance under different terrain characteristics. The numerical simulation algorithm with regard to solving the dynamical equation is described and simulation results are discussed. Finally, one primary prototype and experiment are described. The experimental results show the distance of jumping in the horizontal direction increases with the increasing gear ratio, while the height of jumping decreases in reverse. The jumping robot can enhance the capability to adapt to unknown cluttered environments, such as those encountered in research and rescue, using this strategy.
Salticid predation as one potential driving force of ant mimicry in jumping spiders.
Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min
2011-05-07
Many spiders possess myrmecomorphy, and species of the jumping spider genus Myrmarachne exhibit nearly perfect ant mimicry. Most salticids are diurnal predators with unusually high visual acuity that prey on various arthropods, including conspecifics. In this study, we tested whether predation pressure from large jumping spiders is one possible driving force of perfect ant mimicry in jumping spiders. The results showed that small non-ant-mimicking jumping spiders were readily treated as prey by large ones (no matter whether heterospecific or conspecific) and suffered high attack and mortality rates. The size difference between small and large jumping spiders significantly affected the outcomes of predatory interactions between them: the smaller the juvenile jumping spiders, the higher the predation risk from large ones. The attack and mortality rates of ant-mimicking jumping spiders were significantly lower than those of non-ant-mimicking jumping spiders, indicating that a resemblance to ants could provide protection against salticid predation. However, results of multivariate behavioural analyses showed that the responses of large jumping spiders to ants and ant-mimicking salticids differed significantly. Results of this study indicate that predation pressure from large jumping spiders might be one selection force driving the evolution of nearly perfect myrmecomorphy in spiders and other arthropods.
Heinrich, D; van den Bogert, A J; Nachbauer, W
2014-06-01
Recent data highlight that competitive skiers face a high risk of injuries especially during off-balance jump landing maneuvers in downhill skiing. The purpose of the present study was to develop a musculo-skeletal modeling and simulation approach to investigate the cause-and-effect relationship between a perturbed landing position, i.e., joint angles and trunk orientation, and the peak force in the anterior cruciate ligament (ACL) during jump landing. A two-dimensional musculo-skeletal model was developed and a baseline simulation was obtained reproducing measurement data of a reference landing movement. Based on the baseline simulation, a series of perturbed landing simulations (n = 1000) was generated. Multiple linear regression was performed to determine a relationship between peak ACL force and the perturbed landing posture. Increased backward lean, hip flexion, knee extension, and ankle dorsiflexion as well as an asymmetric position were related to higher peak ACL forces during jump landing. The orientation of the trunk of the skier was identified as the most important predictor accounting for 60% of the variance of the peak ACL force in the simulations. Teaching of tactical decisions and the inclusion of exercise regimens in ACL injury prevention programs to improve trunk control during landing motions in downhill skiing was concluded. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Wallmann, Harvey W; Mercer, John A; McWhorter, J Wesley
2005-08-01
The purpose of this study was to investigate the effects of static stretching of the gastrocnemius muscle on maximal vertical jump performance using electromyographic activity (EMG) of the gastrocnemius musculature to record muscle activation during vertical jump performance. Fourteen healthy adults (8 men and 6 women) aged 18-34 years, who were familiar with the vertical jumping task and had no lower extremity injuries or any bone or joint disorders within the past year, served as participants for this study. After a brief warm-up, participants performed the following sequence: (a) three baseline maximal vertical jump trials, (b) 15 minutes of quiet sitting and three 30-second bilateral static stretches of the gastrocnemius muscles, and (c) 3 maximal vertical jump trials. Jump height data were collected using the Kistler force plate, while muscle activity was recorded during the jumping and stretching trials using a Noraxon telemetry EMG unit. Vertical jump height data as well as EMG values were averaged for the 3 trials and analyzed using paired t-tests for pre- and poststretching (alpha = 0.05). Vertical jump height was 5.6% lower when poststretch heights were compared with prestretch heights (t = -4.930, p static stretching of the gastrocnemius muscles had a negative effect on maximal jumping performance. The practical importance concerns coaches and athletes, who may want to consider the potential adverse effects of performing static stretching of the gastrocnemius muscles only before a jumping event, as jump height may be negatively affected. Future research is required to identify the mechanisms that affect vertical jump performance.
Asymptotic Behaviour and Extinction of Delay Lotka-Volterra Model with Jump-Diffusion
Directory of Open Access Journals (Sweden)
Dan Li
2014-01-01
Full Text Available This paper studies the effect of jump-diffusion random environmental perturbations on the asymptotic behaviour and extinction of Lotka-Volterra population dynamics with delays. The contributions of this paper lie in the following: (a to consider delay stochastic differential equation with jumps, we introduce a proper initial data space, in which the initial data may be discontinuous function with downward jumps; (b we show that the delay stochastic differential equation with jumps associated with our model has a unique global positive solution and give sufficient conditions that ensure stochastically ultimate boundedness, moment average boundedness in time, and asymptotic polynomial growth of our model; (c the sufficient conditions for the extinction of the system are obtained, which generalized the former results and showed that the sufficiently large random jump magnitudes and intensity (average rate of jump events arrival may lead to extinction of the population.
Telemetric control of heart adaptation during automatic and free-fall parachute jumps.
Deroanne, R; Cession-Fossion, A; Juchmes, J; Servais, J C; Petit, J M
1975-02-01
Telmetered heart rate recordings have been ovtaine from 17 parachutists (6 during automatic jumps) 9 Catecholamine (adrenaline and noradrenaline) concentrations have been measured in urine and plasma of six of these subjects. No difference appears between heart rates recorded in the two jumps at egress and at parachute deployment. On the other hand, higher heart rate values are recorded during automatic jumps during descent and at ground impace. The urine catecholamine analysis after jump shows a statistically significant increase in adrenaline and noradrenaline concentration. It is suggested that simulation of the orthosympathetic system is due to two facts; muscular work performed during jumping and the emotional stress which it involves. The importance of these two causes varies with the jump circumstances.
Giant flux jumps through a thin superconducting Nb film in a vortex free region
Energy Technology Data Exchange (ETDEWEB)
Tsindlekht, M.I., E-mail: mtsindl@vms.huji.ac.il [The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Genkin, V.M.; Felner, I.; Zeides, F.; Katz, N. [The Racah Institute of Physics, The Hebrew University of Jerusalem, Jerusalem 91904 (Israel); Gazi, Š.; Chromik, Š. [The Institute of Electrical Engineering SAS, Dúbravská cesta 9, 84104 Bratislava (Slovakia)
2016-10-15
Highlights: Giant magnetic flux jumps into thin-walled cylinder were measured using peak up coil method in a swept magnetic field. Magnetic moment jumps were observed in magnetic fields lower and above Hc1. - Abstract: We measure the dynamics of magnetic field penetration into thin-walled superconducting niobium cylinders. It is shown that magnetic field penetrates through the wall of a cylinder in a series of giant jumps with amplitude 1 - 2 mT and duration of less than a microsecond in a wide range of magnetic fields, including the vortex free region. Surprisingly, the jumps take place when the total current in the wall, not the current density, exceeds a critical value. In addition, there are small jumps and/or smooth penetration, but their contribution reaches only ≃ 20 % of the total penetrating flux. The number of jumps decreases with increased temperature. Thermomagnetic instabilities cannot explain the experimental observations.
Phase jump method for efficiency enhancement in free-electron lasers
Directory of Open Access Journals (Sweden)
Alan Mak
2017-06-01
Full Text Available The efficiency of a free-electron laser can be enhanced by the phase jump method. The method utilizes the phase-shifting chicanes in the drift sections between the undulator segments. By applying appropriate phase jumps, the microbunched electron beam can decelerate and radiate coherently beyond the initial saturation, enabling further energy transfer to the optical beam. This article presents a new physics model for the phase jump method, and supports it with numerical simulations. Based on the electron dynamics in the longitudinal phase space, the model describes the energy extraction mechanism, and addresses the selection criteria for the phase jump magnitude. While the ponderomotive bucket is stationary, energy can be extracted from electrons outside the bucket. With the aid of the new model, a comparison is made between the phase jump method and undulator tapering. The model also explores the potential of the phase jump method to suppress the growth of synchrotron sidebands in the optical spectrum.
Phase jump method for efficiency enhancement in free-electron lasers
Mak, Alan; Curbis, Francesca; Werin, Sverker
2017-06-01
The efficiency of a free-electron laser can be enhanced by the phase jump method. The method utilizes the phase-shifting chicanes in the drift sections between the undulator segments. By applying appropriate phase jumps, the microbunched electron beam can decelerate and radiate coherently beyond the initial saturation, enabling further energy transfer to the optical beam. This article presents a new physics model for the phase jump method, and supports it with numerical simulations. Based on the electron dynamics in the longitudinal phase space, the model describes the energy extraction mechanism, and addresses the selection criteria for the phase jump magnitude. While the ponderomotive bucket is stationary, energy can be extracted from electrons outside the bucket. With the aid of the new model, a comparison is made between the phase jump method and undulator tapering. The model also explores the potential of the phase jump method to suppress the growth of synchrotron sidebands in the optical spectrum.
Marlene Schoeman, PhD; Ceri E. Diss, PhD; Siobhan C. Strike, PhD
2014-01-01
Loading symmetry during vertical jump landings between a person with amputation’s intact and prosthetic limbs was assessed to determine the role of each limb in controlling the downward momentum of the center of mass during landing. Six participants with unilateral transtibial amputation (TTA) and ten nondisabled participants completed 10 maximal vertical jumps, of which the highest jump was analyzed. Contralateral symmetry was assessed through the Symmetry Index (SI), while symmetry at the g...
A GENERALIZED EXPLICIT SOLUTION OF THE SEQUENT DEPTH RATIO FOR THE HYDRAULIC JUMP
Institute of Scientific and Technical Information of China (English)
NI Han-gen; LIU Ya-kun
2005-01-01
By use of the property of the momentum equation describing the hydraulic jump in rectangular channels, a generalized solution of the sequent depth ratio was given. On the basis of the generalized solution the explicit solutions of the sequent depth ratio were obtained for the hydraulic jump in gradual enlargements,the corresponding relative energy losses were also presented, and a method to determine the location of hydraulic jump in gradual enlargements was proposed.
Jump Variation Estimation with Noisy High Frequency Financial Data via Wavelets
Directory of Open Access Journals (Sweden)
Xin Zhang
2016-08-01
Full Text Available This paper develops a method to improve the estimation of jump variation using high frequency data with the existence of market microstructure noises. Accurate estimation of jump variation is in high demand, as it is an important component of volatility in finance for portfolio allocation, derivative pricing and risk management. The method has a two-step procedure with detection and estimation. In Step 1, we detect the jump locations by performing wavelet transformation on the observed noisy price processes. Since wavelet coefficients are significantly larger at the jump locations than the others, we calibrate the wavelet coefficients through a threshold and declare jump points if the absolute wavelet coefficients exceed the threshold. In Step 2 we estimate the jump variation by averaging noisy price processes at each side of a declared jump point and then taking the difference between the two averages of the jump point. Specifically, for each jump location detected in Step 1, we get two averages from the observed noisy price processes, one before the detected jump location and one after it, and then take their difference to estimate the jump variation. Theoretically, we show that the two-step procedure based on average realized volatility processes can achieve a convergence rate close to O P ( n − 4 / 9 , which is better than the convergence rate O P ( n − 1 / 4 for the procedure based on the original noisy process, where n is the sample size. Numerically, the method based on average realized volatility processes indeed performs better than that based on the price processes. Empirically, we study the distribution of jump variation using Dow Jones Industrial Average stocks and compare the results using the original price process and the average realized volatility processes.
DEFF Research Database (Denmark)
Wang, Yun; Wu, Qiuwei
2014-01-01
This paper analysis the electromagnetic transient response characteristics of DFIG under symmetrical and asymmetrical cascading grid fault conditions considering phaseangel jump of grid. On deriving the dynamic equations of the DFIG with considering multiple constraints on balanced and unbalanced...... conditions, phase angel jumps, interval of cascading fault, electromagnetic transient characteristics, the principle of the DFIG response under cascading voltage fault can be extract. The influence of grid angel jump on the transient characteristic of DFIG is analyzed and electromagnetic response...
Adaptive Continuous time Markov Chain Approximation Model to\\ud General Jump-Diffusions
Cerrato, Mario; Lo, Chia Chun; Skindilias, Konstantinos
2011-01-01
We propose a non-equidistant Q rate matrix formula and an adaptive numerical algorithm for a continuous time Markov chain to approximate jump-diffusions with affine or non-affine functional specifications. Our approach also accommodates state-dependent jump intensity and jump distribution, a flexibility that is very hard to achieve with other numerical methods. The Kologorov-Smirnov test shows that the proposed Markov chain transition density converges to the one given by the likelihood expan...
SHORT-TERM JUMP ACTIVITY ON BONE METABOLISM IN FEMALE COLLEGE-AGED NON-ATHLETES
Directory of Open Access Journals (Sweden)
Kohei Kishimoto
2012-03-01
Full Text Available There have been few studies examining the short-term effect of high-impact activities on bone metabolism measured by bone serum marker concentrations. The purpose of this study was to examine the effect of short-term high-impact jump activity on bone turnover in female college-aged non-athletes. Twenty six healthy females were randomly assigned to a control or jump group. The subjects jumped 5 days per week for 2 weeks. The participants completed 10 jumps per session. A general health questionnaire and a bone-specific physical activity assessment instrument (BPAQ were completed. BPAQ scores were calculated based on the past history of exercise. Blood draws were taken in both groups before and after the two-week experimental period. The vertical ground reaction force (VGRF of all jumps and jump height were measured for each subject daily and the osteogenic index (OI was measured. Concentrations of serum osteocalcin (OC, Bone Specific Alkaline Phosphatase (BAP, C-Terminal Telopeptides of Type I Collagen (CTX and plasma Tartrate-Resistant Acid Phosphatase (TRAP5b were assessed pre and post jump protocol to measure bone formation and resoprtion respectively. A significant interaction (time x group was found in TRAP5b, and BAP values (p < 0.05. There was a significant decrease in CTX and BAP values in the jump group (p < 0.05 after the two week jump protocol. No significant interactions or changes were observed in OC values for either the jump or the control group. Two weeks of jump activity consisting of 10 jumps/day for 5 days/week with a weekly osteogenic index of 52.6 significantly decreased markers of bone resorption (TRAP5b and CTX and bone formation (BAP in young female non- athletes.
Effects of three different stretching techniques on vertical jumping performance.
Kirmizigil, Berkiye; Ozcaldiran, Bahtiyar; Colakoglu, Muzaffer
2014-05-01
The aim of this study was to evaluate 3 different flexibility techniques: (a) ballistic stretching (BS), (b) proprioceptive neuromuscular facilitation stretching (PNF) + BS, and (c) PNF + static stretching (SS) on vertical jump (VJ) performance and to determine the most appropriate stretching method during warm-up period before explosive force disciplines. One hundred voluntary male athletes participated in this study. All subjects performed aerobic warm-up (5-minute jog) followed by BS (5 seconds for each stretching exercise), PNF + BS (PNF performed followed by 5 seconds of BS), and PNF + SS (PNF performed followed by 30 seconds of SS) treatment protocol, respectively in the same day. Each stretching treatment was applied for 4 sets bilaterally. In all stretching treatments, lumbar extensor, gluteus maximus, and hamstring muscles were stretched with a single stretching exercise. After a 2-minute brief rest period, participants performed 3 trials of VJ test followed by one of the treatment protocols. Vertical jump performance was evaluated by countermovement jump (CMJ). Participants were divided into 3 groups according to their flexibility and prejump performances after warm-up. For each individual group and the whole group, after all treatments, differences in CMJ values were obtained (p ≤ 0.05). Ballistic stretching increased the VJ performance in the groups with low and average flexibility, poor prejumping performance, and also in the whole group (p ≤ 0.05). Proprioceptive neuromuscular facilitation stretching + BS affected VJ performance in the group of participants with high flexibility (p ≤ 0.05). Proprioceptive neuromuscular facilitation + SS decreased VJ performance in groups of participants with high flexibility, moderate, and high prejumping performance and in whole group (p ≤ 0.05). Ballistic stretching method increased VJ height, therefore seems to be more suitable than PNF + SS and PNF + BS before events that rely on explosive power as a part
Assessment of musculoskeletal system in women with jumping mechanography
Directory of Open Access Journals (Sweden)
Yannis Dionyssiotis
2009-08-01
Full Text Available Yannis Dionyssiotis1,2, Antonios Galanos1, Georgios Michas1, Georgios Trovas1, Georgios P Lyritis11Laboratory for Research of the Musculoskeletal System, University of Athens, KAT Hospital, Kifissia, Greece; 2Rehabilitation Department, Rhodes General Hospital, Rhodes, GreeceAbstract: The purpose of this study was to investigate and add reference data about the musculoskeletal system in women. The mechanography system of the Leonardo™ platform (Novotec, Germany was used to measure parameters of movement (velocity, force, power in 176 healthy Greek women aged 20–79 years, separated according to age decade in six groups: group 1 (n = 12, 20–29 years; group 2 (n = 14, 30–39 years; group 3 (n = 33, 40–49 years; group 4 (n = 59, 50–59 years including 21 postmenopausal; group 5 (n = 31, 60–69 years including 12 postmenopausal; and group 6 (n = 27, 70–79 years all postmenopausal. This system measures forces applied to the plate over time, calculates through acceleration the vertical velocity of center of gravity and using force and velocity it calculates power of vertical movements. All women performed a counter-movement jump (brief squat before the jump with freely moving arms. Weight was recorded on the platform before the jump and height was measured with a wall-mounted ruler. Body weight and body mass index were gradually increased; on the contrary height and all movement parameters except force (velocity, power were statistically decreased during aging and after menopause.Keywords: biomechanics, ground reaction force, power, women, menopause
Motoneuron membrane potentials follow a time inhomogeneous jump diffusion process
DEFF Research Database (Denmark)
Jahn, Patrick; Berg, Rune W; Hounsgaard, Jørn
2011-01-01
Stochastic leaky integrate-and-fire models are popular due to their simplicity and statistical tractability. They have been widely applied to gain understanding of the underlying mechanisms for spike timing in neurons, and have served as building blocks for more elaborate models. Especially...... models can only be applied over short time windows. However, experimental data show varying time constants, state dependent noise, a graded firing threshold and time-inhomogeneous input. In the present study we build a jump diffusion model that incorporates these features, and introduce a firing...
The physics of articulated toys - a jumping and rotating kangaroo
Güémez, J
2014-01-01
We describe the physics of an articulated toy with an internal source of energy provided by a spiral spring. The toy is a funny low cost kangaroo which jumps and rotates. The study consists of a mechanical and a thermodynamical analysis which makes use of the Newton and center of mass equations, the rotational equations and the first law of thermodynamics. This amazing toy provides a nice demonstrative example how new physics insights can be brought about when links with thermodynamics are established in the study of mechanical systems.
Analysis and design of singular Markovian jump systems
Wang, Guoliang; Yan, Xinggang
2014-01-01
This monograph is an up-to-date presentation of the analysis and design of singular Markovian jump systems (SMJSs) in which the transition rate matrix of the underlying systems is generally uncertain, partially unknown and designed. The problems addressed include stability, stabilization, H∞ control and filtering, observer design, and adaptive control. applications of Markov process are investigated by using Lyapunov theory, linear matrix inequalities (LMIs), S-procedure and the stochastic Barbalat's Lemma, among other techniques.Features of the book include:·???????? study of the stability pr
Stochastic Stability Analysis for Markovian Jump Neutral Nonlinear Systems
Directory of Open Access Journals (Sweden)
Bo Wang
2012-10-01
Full Text Available In this paper, the stability problem is studied for a class of Markovian jump neutral nonlinear systems with time-varying delay. By Lyapunov-Krasovskii function approach, a novel mean-square exponential stability criterion is derived for the situations that the system's transition rates are completely accessible, partially accessible and non-accessible, respectively. Moreover, the developed stability criterion is extended to the systems with different bounded sector nonlinear constraints. Finally, some numerical examples are provided to illustrate the effectiveness of the proposed methods.
Multifractal Analysis of Infinite Products of Stationary Jump Processes
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Petteri Mannersalo
2010-01-01
Full Text Available There has been a growing interest in constructing stationary measures with known multifractal properties. In an earlier paper, the authors introduced the multifractal products of stochastic processes (MPSP and provided basic properties concerning convergence, nondegeneracy, and scaling of moments. This paper considers a subclass of MPSP which is determined by jump processes with i.i.d. exponentially distributed interjump times. Particularly, the information dimension and a multifractal spectrum of the MPSP are computed. As a side result it is shown that the random partitions imprinted naturally by a family of Poisson point processes are sufficient to determine the spectrum in this case.
Effects of Foam Rolling on Vertical Jump Performance
Andrew Jones; Brown, Lee E.; Coburn, Jared W.; Guillermo J. Noffal
2015-01-01
Background: Foam rolling is a popular activity utilized by strength and conditioning coaches as it is believed to increase muscle length and break up fibrous adhesions located in connective tissue. However, there is little research investigating the effects of foam rolling on athletic performance. Objective: The purpose of this study was to investigate the effects of lower body foam rolling on vertical jump performance. Methods: Twenty males (age 24.05 ± 2.02 years; height 177.43 ± 6.31 cm; m...
Suppressing decoherence of quantum algorithms by jump codes
Kern, O; Kern, Oliver; Alber, Gernot
2005-01-01
The stabilizing properties of one-error correcting jump codes are explored under realistic non-ideal conditions. For this purpose the quantum algorithm of the tent-map is decomposed into a universal set of Hamiltonian quantum gates which ensure perfect correction of spontaneous decay processes under ideal circumstances even if they occur during a gate operation. An entanglement gate is presented which is capable of entangling any two logical qubits of different one-error correcting code spaces. With the help of this gate simultaneous spontaneous decay processes affecting physical qubits of different code spaces can be corrected and decoherence can be suppressed significantly.
Tailored jump operators for purely dissipative quantum magnetism
Weimer, Hendrik
2017-01-01
I propose an architecture for the realization of dissipative quantum many-body spin models. The dissipative processes are mediated by interactions with auxiliary particles and lead to a widely tunable class of correlated quantum jump operators. These findings enable the investigation of purely dissipative spin models, where coherent dynamics is entirely absent. I provide a detailed review of a recently introduced variational method to analyze such dissipative quantum many-body systems, and I discuss a specific example in terms of a purely dissipative Heisenberg model, for which I find an additional disordered phase that is not present in the corresponding ground state phase diagram.
Exponential stability for uncertain neutral systems with Markov jumps
Institute of Scientific and Technical Information of China (English)
Shuping HE; Fei LIU
2009-01-01
This paper deals with the global exponential stability problems for stochastic neutral Markov jump sys-tems(MJSs) with uncertain parameters and multiple time-delays,The delays are respectively considered as constant and time varying cases,and the uncertainties are assumed to be norm bounded.By selecting appropriate Lyapunov-Krasovskii functions,it gives the sufficient condition such that the uncertain neutral MJSs are globally exponentially stochastically stable for all admissible uncertainties.The stability criteria are formulated in the form of linear matrix inequalities(LMIs),which can be easily checked in practice.Finally,two numerical examples are exploited to illustrate the effectiveness of the developed techniques.
Transmittance jump in a thin aluminium layer during laser ablation
Energy Technology Data Exchange (ETDEWEB)
Bykovsky, N E; Senatsky, Yu V [P N Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Pershin, S M; Samokhin, A A [A M Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)
2016-02-28
A jump in the transmittance (from ∼0.1% to ∼50% for ∼1 ns) of an optical gate on a Mylar film (a thin aluminium layer on a Lavsan substrate) irradiated by nanosecond (10{sup -7} – 10{sup -8} s) pulses of a neodymium laser with an intensity up to 0.1 GW cm{sup -2} has been recorded. The mechanism of a fast (10{sup -10} – 10{sup -11} s) increase in the transmittance of the aluminium layer upon its overheating (without boiling) to the metal – insulator phase-transition temperature is discussed. (interaction of laser radiation with matter. laser plasma)
Hard-sphere interactions in velocity-jump models
Franz, Benjamin; Taylor-King, Jake P.; Yates, Christian; Erban, Radek
2016-07-01
Group-level behavior of particles undergoing a velocity-jump process with hard-sphere interactions is investigated. We derive N -particle transport equations that include the possibility of collisions between particles and apply different approximation techniques to get expressions for the dependence of the collective diffusion coefficient on the number of particles and their diameter. The derived approximations are compared with numerical results obtained from individual-based simulations. The theoretical results compare well with Monte Carlo simulations providing the excluded-volume fraction is small.
Hard-sphere interactions in velocity jump models
Franz, Benjamin; Yates, Christian; Erban, Radek
2014-01-01
Group-level behaviour of particles undergoing a velocity jump process with hard-sphere interactions is investigated. We derive $N$-particle transport equations that include the possibility of collisions between particles and apply different approximation techniques to get expressions for the dependence of the collective diffusion coefficient on the number of particles and their diameter. The derived approximations are compared with numerical results obtained from individual-based simulations. The theoretical results compare well with Monte Carlo simulations providing the excluded volume fraction is small.
Thermodynamics of quantum-jump-conditioned feedback control.
Strasberg, Philipp; Schaller, Gernot; Brandes, Tobias; Esposito, Massimiliano
2013-12-01
We consider open quantum systems weakly coupled to thermal reservoirs and subjected to quantum feedback operations triggered with or without delay by monitored quantum jumps. We establish a thermodynamic description of such systems and analyze how the first and second law of thermodynamics are modified by the feedback. We apply our formalism to study the efficiency of a qubit subjected to a quantum feedback control and operating as a heat pump between two reservoirs. We also demonstrate that quantum feedbacks can be used to stabilize coherences in nonequilibrium stationary states which in some cases may even become pure quantum states.
Tailored jump operators for purely dissipative quantum magnetism
Weimer, Hendrik
2016-01-01
I propose an archtitecture for the realization of dissipative quantum many-body spin models. The dissipative processes are mediated by interactions with auxiliary particles and lead to a widely tunable class of correlated quantum jump operators. These findings enable the investigation of purely dissipative spin models, where coherent dynamics is entirely absent. I provide a detailed review of a recently introduced variational method to analyze such dissipative quantum many-body systems, and I discuss a specific example in terms of a purely dissipative Heisenberg model, for which I find an additional disordered phase that is not present in the corresponding ground state phase diagram.
Intertime jump statistics of state-dependent Poisson processes.
Daly, Edoardo; Porporato, Amilcare
2007-01-01
A method to obtain the probability distribution of the interarrival times of jump occurrences in systems driven by state-dependent Poisson noise is proposed. Such a method uses the survivor function obtained by a modified version of the master equation associated to the stochastic process under analysis. A model for the timing of human activities shows the capability of state-dependent Poisson noise to generate power-law distributions. The application of the method to a model for neuron dynamics and to a hydrological model accounting for land-atmosphere interaction elucidates the origin of characteristic recurrence intervals and possible persistence in state-dependent Poisson models.
Intertime jump statistics of state-dependent Poisson processes
Daly, Edoardo; Porporato, Amilcare
2007-01-01
A method to obtain the probability distribution of the interarrival times of jump occurrences in systems driven by state-dependent Poisson noise is proposed. Such a method uses the survivor function obtained by a modified version of the master equation associated to the stochastic process under analysis. A model for the timing of human activities shows the capability of state-dependent Poisson noise to generate power-law distributions. The application of the method to a model for neuron dynamics and to a hydrological model accounting for land-atmosphere interaction elucidates the origin of characteristic recurrence intervals and possible persistence in state-dependent Poisson models.
Orthogonal Expansions for VIX Options Under Affine Jump Diffusions
DEFF Research Database (Denmark)
Barletta, Andrea; Nicolato, Elisa
2017-01-01
In this work we derive new closed–form pricing formulas for VIX options in the jump-diffusion SVJJ model proposed by Duffie et al. (2000). Our approach is based on the classic methodology of approximating a density function with an orthogonal expansion of polynomials weighted by a kernel....... Orthogonal expansions based on the Gaussian distribution, such as Edgeworth or Gram–Charlier expansions, have been successfully employed by a number of authors in the context of equity options. However, these expansions are not quite suitable for volatility or variance densities as they inherently assign...
Multiscale integration schemes for jump-diffusion systems
Energy Technology Data Exchange (ETDEWEB)
Givon, D.; Kevrekidis, I.G.
2008-12-09
We study a two-time-scale system of jump-diffusion stochastic differential equations. We analyze a class of multiscale integration methods for these systems, which, in the spirit of [1], consist of a hybridization between a standard solver for the slow components and short runs for the fast dynamics, which are used to estimate the effect that the fast components have on the slow ones. We obtain explicit bounds for the discrepancy between the results of the multiscale integration method and the slow components of the original system.
A new design of ski-jump-step spillway
Institute of Scientific and Technical Information of China (English)
吴建华; 钱尚拓; 马飞
2016-01-01
A new kind of ski-jump-step spillway was reported. By means of the effects of the aeration basin, it supplies the sufficient aeration flow from the first step for stepped chutes, especially for large unit discharge. The physical model experiments demonstrated that, this spillway makes a far better hydraulic performance as regards energy dissipation and cavitation damage protection than the current and conventional stepped spillways, and the unit discharge can be enlarged from about 50 m3/s-60 m3/s·m to 118 m3/s·m in order to significantly reduce the width of the spillways.
European option pricing under the Student's t noise with jumps
Wang, Xiao-Tian; Li, Zhe; Zhuang, Le
2017-03-01
In this paper we present a new approach to price European options under the Student's t noise with jumps. Through the conditional delta hedging strategy and the minimal mean-square-error hedging, a closed-form solution of the European option value is obtained under the incomplete information case. In particular, we propose a Value-at-Risk-type procedure to estimate the volatility parameter σ such that the pricing error is in accord with the risk preferences of investors. In addition, the numerical results of us show that options are not priced in some cases in an incomplete information market.
The effects of temperature and body mass on jump performance of the locust Locusta migratoria.
Directory of Open Access Journals (Sweden)
Edward P Snelling
Full Text Available Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m scales with body mass (M; g according to the power equation D = 0.35M (0.17±0.08 (95% CI, jump take-off angle (A; degrees scales as A = 52.5M (0.00±0.06, and jump energy (E; mJ per jump scales as E = 1.91M (1.14±0.09. Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (L f+t; mm of the femur and tibia of the hind leg, L f+t = 34.9M (0.37±0.02. The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12% legs and a relatively larger (11% femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight.
Deinzer, R; Kirschbaum, C; Gresele, C; Hellhammer, D H
1997-04-01
The present study examined the adrenocortical response to 3 consecutive parachute jumps and a poststress h-CRH challenge. Fifteen participants in a parachute-jumping course took saliva samples for later cortisol analysis every 20 min throughout the day, when they accomplished their very first 3 parachute jumps and throughout a control day. The effects of an h-CRH challenge on salivary cortisol were assessed in the evening of the jumping day and on a control day. Parachute jumping induced 3 distinct highly significant adrenocortical responses. The respective cortisol increases for the first, second, and third jump were 39.4 +/- 26.5 nmol/1, 31.4 +/- 21.4 nmol/l, and 16.5 +/- 11.9 nmol/l. Cortisol responses to the first and second jump did not differ but the response to the third jump was significantly reduced [t(13) = 3.11; p = 0.008]. Two groups of subjects were identified, "decreasers," whose response decreased from one to the other jump, and "increasers," whose response remained unchanged or increased. The magnitude of the preceding cortisol response of decreasers exceeded that of increasers significantly by about 30 nmol. The mean adrenocortical effects of the poststress h-CRH challenge and the time-matched challenge on a control day did not differ although, in 4 subjects, the poststress adrenocortical response to h-CRH was completely suppressed.
Prolactin, thyrotropin, and growth hormone release during stress associated with parachute jumping.
Noel, G L; Dimond, R C; Earll, J M; Frantz, A G
1976-05-01
Prolactin, growth hormone, and thyrotropin (TSH) release during the stress of parachute jumping has been evaluated in 14 male subjects. Subjects were studied at several times before and immediately after their first military parachute jump. All three hormones had risen significantly 1 to 14 min after the jump, compared to mean levels measured immediately beforehand. Earlier studies of physical exercise by ourselves and others would suggest that emotional stress played a role in producing changes of this magnitude. We conclude that prolactin, TSH, and growth hormone are released in physiologically significant amounts in association with the stress of parachute jumping.
Discrete Element Method simulations of standing jumps in granular flows down inclines
Directory of Open Access Journals (Sweden)
Méjean Ségolène
2017-01-01
Full Text Available This paper describes a numerical set-up which uses Discrete Element Method to produce standing jumps in flows of dry granular materials down a slope in two dimensions. The grain-scale force interactions are modeled by a visco-elastic normal force and an elastic tangential force with a Coulomb threshold. We will show how it is possible to reproduce all the shapes of the jumps observed in a previous laboratory study: diffuse versus steep jumps and compressible versus incompressible jumps. Moreover, we will discuss the additional measurements that can be done thanks to discrete element modelling.
Application of a tri-axial accelerometer to estimate jump frequency in volleyball.
Jarning, Jon M; Mok, Kam-Ming; Hansen, Bjørge H; Bahr, Roald
2015-03-01
Patellar tendinopathy is prevalent among athletes, and most likely associated with a high jumping load. If methods for estimating jump frequency were available, this could potentially assist in understanding and preventing this condition. The objective of this study was to explore the possibility of using peak vertical acceleration (PVA) or peak resultant acceleration (PRA) measured by an accelerometer to estimate jump frequency. Twelve male elite volleyball players (22.5 ± 1.6 yrs) performed a training protocol consisting of seven typical motion patterns, including jumping and non-jumping movements. Accelerometer data from the trial were obtained using a tri-axial accelerometer. In addition, we collected video data from the trial. Jump-float serving and spike jumping could not be distinguished from non-jumping movements using differences in PVA or PRA. Furthermore, there were substantial inter-participant differences in both the PVA and the PRA within and across movement types (p volleyball. A method for acquiring real-time estimates of jump frequency remains to be verified. However, there are several alternative approaches, and further investigations are needed.
Suicide by jumping from high-rise hotels. Fulton County, Georgia, 1967-1986.
Hanzlick, R; Masterson, K; Walker, B
1990-12-01
During a 20-year period from 1967 through 1986, 19 suicidal jumps from high-rise hotels (HRHs) accounted for 24% of all fatal jumping episodes and 1% of all suicides in Fulton County, Georgia, U.S.A. The rate of suicidal jumps from HRHs did not increase during the study period. The number of fatal jumps per hotel-year correlated with the height of the interior hotel atrium. The mean age for all victims was 34 years, and 63% of victims were white males. The majority of victims were local residents who were alone when they jumped and were not registered hotel guests. Registered guests tended to jump from the floor on which their room was located whereas nonregistered individuals tended to jump from the upper-most floors in the hotel. Of 19 HRH jumps, 13 occurred from the inside. Suicide notes were found in 37% of cases. HRH jumps were least common between 6 p.m. and midnight, all decedents were dressed in street clothing, only one was heard to have screamed, and all but one were dead on the scene. Alcohol and drug involvement was minimal. We hope that this information will be useful to those who investigate such deaths and to those who study the behavioral manifestations of suicide.
The effects of temperature and body mass on jump performance of the locust Locusta migratoria.
Snelling, Edward P; Becker, Christie L; Seymour, Roger S
2013-01-01
Locusts jump by rapidly releasing energy from cuticular springs built into the hind femur that deform when the femur muscle contracts. This study is the first to examine the effect of temperature on jump energy at each life stage of any orthopteran. Ballistics and high-speed cinematography were used to quantify the energy, distance, and take-off angle of the jump at 15, 25, and 35°C in the locust Locusta migratoria. Allometric analysis across the five juvenile stages at 35°C reveals that jump distance (D; m) scales with body mass (M; g) according to the power equation D = 0.35M (0.17±0.08 (95% CI)), jump take-off angle (A; degrees) scales as A = 52.5M (0.00±0.06), and jump energy (E; mJ per jump) scales as E = 1.91M (1.14±0.09). Temperature has no significant effect on the exponent of these relationships, and only a modest effect on the elevation, with an overall Q10 of 1.08 for jump distance and 1.09 for jump energy. On average, adults jump 87% farther and with 74% more energy than predicted based on juvenile scaling data. The positive allometric scaling of jump distance and jump energy across the juvenile life stages is likely facilitated by the concomitant relative increase in the total length (L f+t; mm) of the femur and tibia of the hind leg, L f+t = 34.9M (0.37±0.02). The weak temperature-dependence of jump performance can be traced to the maximum tension of the hind femur muscle and the energy storage capacity of the femur's cuticular springs. The disproportionately greater jump energy and jump distance of adults is associated with relatively longer (12%) legs and a relatively larger (11%) femur muscle cross-sectional area, which could allow more strain loading into the femur's cuticular springs. Augmented jump performance in volant adult locusts achieves the take-off velocity required to initiate flight.
Towards Stability Analysis of Jump Linear Systems with State-Dependent and Stochastic Switching
Tejada, Arturo; Gonzalez, Oscar R.; Gray, W. Steven
2004-01-01
This paper analyzes the stability of hierarchical jump linear systems where the supervisor is driven by a Markovian stochastic process and by the values of the supervised jump linear system s states. The stability framework for this class of systems is developed over infinite and finite time horizons. The framework is then used to derive sufficient stability conditions for a specific class of hybrid jump linear systems with performance supervision. New sufficient stochastic stability conditions for discrete-time jump linear systems are also presented.
No apparent ecological trend to the flight-initiating jump performance of five bat species.
Gardiner, James D; Nudds, Robert L
2011-07-01
The jump performance of five insectivorous bat species (Miniopterus schreibersii, Myotis blythii, Myotis capaccinii, Myotis myotis and Rhinolophus blasii) was filmed using a high-speed camera. All study bats jumped using a similar technique, with the wing musculature providing the force. The bats jumped off the wrist joint of their wings, typically with their feet already off the ground. Contrary to expectations, jump performance did not correlate with ecology and was instead strongly determined by body size. In general, the larger bats produced more jump force, left the ground at higher speeds and jumped higher than the smaller bats. The differences in force production disappeared when the data were corrected for body size, with the exception of Myotis capaccinii, which produced significantly less force. Scaling of jump performance with body size measured here was compared against two existing muscle performance scaling models. The model suggesting that muscle contraction velocity is proportional to muscle length was better supported than that based on muscle cross-sectional area. Both models, however, failed to accurately predict the scaling of jump forces, with the slope of the relationship being significantly steeper than predicted, highlighting the need for further investigations of vertebrate muscle performance scaling. The results of this study indicate that a bat's jumping ability is a secondary locomotor ability that uses the strongly selected-for flight apparatus with no apparent ecological trend present, i.e. flight so dominates bat locomotor morphology that other locomotor abilities tend to be derivative.
Validation of the iPhone app using the force platform to estimate vertical jump height.
Carlos-Vivas, Jorge; Martin-Martinez, Juan P; Hernandez-Mocholi, Miguel A; Perez-Gomez, Jorge
2016-09-22
Vertical jump performance has been evaluated with several devices: force platforms, contact mats, Vertec, accelerometers, infrared cameras and high-velocity cameras; however, the force platform is considered the gold standard for measuring vertical jump height. The purpose of this study was to validate the iPhone app, My Jump, that measures vertical jump height by comparing it with other methods that use the force platform to estimate vertical jump height, namely, vertical velocity at take-off and time in the air. A total of 40 sport sciences students (age 21.4 ± 1.9 years) completed five countermovement jumps (CMJs) over a force platform. Thus, 200 CMJ heights were evaluated from the vertical velocity at take-off and the time in the air using the force platform, and from the time in the air with the mobile application My Jump. The height obtained was compared using the intraclass correlation coefficient (ICC). Correlation between APP and force platform using the time in the air was perfect (ICC = 1.000, P vertical velocity at take-off was also very high (ICC = 0.996, P vertical jump performance; however, vertical jump height is slightly overestimated compared with that of the force platform.
Stationary distribution and ergodicity of a stochastic food-chain model with Lévy jumps
Yu, Jingyi; Liu, Meng
2017-09-01
In this paper, a three-species stochastic food-chain model with Lévy jumps is proposed and analyzed. Sharp sufficient criteria for the existence and uniqueness of an ergodic stationary distribution are established. The effects of Lévy jumps on the existence of the stationary distribution are revealed: in some cases, the Lévy jumps could make the stationary distribution appear, while in some cases, the Lévy jumps could make the stationary distribution disappear. Some numerical simulations are introduced to illustrate the theoretical results.
Optimal dividend policies with transaction costs for a class of jump-diffusion processes
DEFF Research Database (Denmark)
Hunting, Martin; Paulsen, Jostein
2013-01-01
his paper addresses the problem of finding an optimal dividend policy for a class of jump-diffusion processes. The jump component is a compound Poisson process with negative jumps, and the drift and diffusion components are assumed to satisfy some regularity and growth restrictions. Each dividend...... payment is changed by a fixed and a proportional cost, meaning that if ξ is paid out by the company, the shareholders receive kξ−K, where k and K are positive. The aim is to maximize expected discounted dividends until ruin. It is proved that when the jumps belong to a certain class of light...
Directory of Open Access Journals (Sweden)
Barry P. Boden
2009-12-01
Full Text Available Recent studies have focused on gender differences in movement patterns as risk factors for ACL injury. Understanding intrinsic and extrinsic factors which contribute to movement patterns is critical to ACL injury prevention efforts. Isometric lower- extremity muscular strength, anthropometrics, and jump-landing technique were analyzed for 2,753 cadets (1,046 female, 1,707 male from the U.S. Air Force, Military and Naval Academies. Jump- landings were evaluated using the Landing Error Scoring System (LESS, a valid qualitative movement screening tool. We hypothesized that distinct anthropometric factors (Q-angle, navicular drop, bodyweight and muscle strength would predict poor jump-landing technique in males versus females, and that female cadets would have higher scores (more errors on a qualitative movement screen (LESS than males. Mean LESS scores were significantly higher in female (5.34 ± 1.51 versus male (4.65 ± 1.69 cadets (p < 0.001. Qualitative movement scores were analyzed using factor analyses, yielding five factors, or "patterns", contributing to poor landing technique. Females were significantly more likely to have poor technique due to landing with less hip and knee flexion at initial contact (p < 0.001, more knee valgus with wider landing stance (p < 0. 001, and less flexion displacement over the entire landing (p < 0.001. Males were more likely to have poor technique due to landing toe-out (p < 0.001, with heels first, and with an asymmetric foot landing (p < 0.001. Many of the identified factor patterns have been previously proposed to contribute to ACL injury risk. However, univariate and multivariate analyses of muscular strength and anthropometric factors did not strongly predict LESS scores for either gender, suggesting that changing an athlete's alignment, BMI, or muscle strength may not directly improve his or her movement patterns
Patterson, Carson; Raschner, Christian; Platzer, Hans-Peter
2014-09-01
The purposes of this study were to test the reproducibility of the 2.5-minute loaded repeated jump test (LRJT) and to test the effectiveness of general preparation period (GPP) training on anaerobic fitness of elite alpine ski racers with the LRJT. Thirteen male volunteers completed 2 LRJTs to examine reliability. Nine male Austrian elite junior racers were tested in June and October 2009. The LRJT consisted of 60 loaded countermovement jumps (LCMJs) with a loaded barbell equivalent to 40% bodyweight. Before the LRJT, the power (P) of a single LCMJ was determined. Power was calculated from ground reaction forces. The mean P was calculated for the complete test and for each 30-second interval. The interclass correlation coefficients (between 0.88 and 0.99) for main variables of the LRJT demonstrated a high reliability. A repeated-measures analysis of variance indicated that anaerobic capacity was significantly higher in October (p ≤ 0.05). The ski racers' single LCMJ P increased from 37.0 ± 1.2 W·kg to 39.0 ± 1.4 W·kg. The mean P of the total test improved from 33.6 ± 1.2 W·kg to 35.8 ± 1.3 W·kg, but relative effect of fatigue did not change. The GPP training improved the athletes' ability to produce and maintain muscular power. The LRJT is a reliable anaerobic test suitable for all alpine ski racing events because the 60 jumps simulate the approximate number of gates in slalom and giant slalom races and the 2.5 minutes is equivalent to the duration of the longest downhill race.
Quantum jump from singularity to outside of black hole
Energy Technology Data Exchange (ETDEWEB)
Dündar, Furkan Semih [Physics and Mathematics Departments, Sakarya University, 54050, Sakarya (Turkey); Hajian, Kamal [School of Physics, Institute for Research in Fundamental Sciences, P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Department of Physics, Sharif University of Technology, P.O. Box 11365-8639, Tehran (Iran, Islamic Republic of)
2016-02-26
Considering the role of black hole singularity in quantum evolution, a resolution to the firewall paradox is presented. It is emphasized that if an observer has the singularity as a part of his spacetime, then the semi-classical evolution would be non-unitary as viewed by him. Specifically, a free-falling observer inside the black hole would have a Hilbert space with non-unitary evolution; a quantum jump for particles encountering the singularity to outside of the horizon as late Hawking radiations. The non-unitarity in the jump resembles the one in collapse of wave function, but preserves entanglements. Accordingly, we elaborate the first postulate of black hole complementarity: freely falling observers who pass through the event horizon would have non-unitary evolution, while it does not have physically measurable effects for them. Besides, no information would be lost in the singularity. Taking the modified picture into account, the firewall paradox can be resolved, respecting No Drama. A by-product of our modification is that roughly half of the entropy of the black hole is released close to the end of evaporation in the shape of very hot Hawking radiation.
Aerodynamics of ski jumping flight and its control: I. Experiments
Jung, Daehan; Bang, Kyeongtae; Kim, Heesu; Ahn, Eunhye; Choi, Haecheon
2015-11-01
In a ski jumping competition, it is essential to analyze the effect of various posture parameters of a ski jumper to achieve a longer flight distance. For this purpose, we construct a model of a ski jumper by using three-dimensional surface data obtained by scanning a ski jumper's body (Mr. Chil-Ku Kang, member of the Korean national team). An experiment on this model is conducted in a wind tunnel. We consider four posture parameters (forward leaning angle, ski opening angle, ski rolling angle, and ski spacing) and measure the drag and lift forces for various flight postures at various angles of attack (α = 0° - 40°) and Reynolds numbers (Re = 5.4 × 105 - 1.6 × 106) based on the length of the jump ski. Then, we derive optimum values of posture parameters for maximum lift-to-drag ratio using a response surface method. We also conduct a full-scale wind tunnel experiment with members of the Korean national team and confirm the results obtained from the experiment on the model. Supported by the NRF program (2014M3C1B1033848).
Robophysical study of jumping dynamics on granular media
Aguilar, Jeffrey; Goldman, Daniel I.
2016-03-01
Characterizing forces on deformable objects intruding into sand and soil requires understanding the solid- and fluid-like responses of such substrates and their effect on the state of the object. The most detailed studies of intrusion in dry granular media have revealed that interactions of fixed-shape objects during free impact (for example, cannonballs) and forced slow penetration can be described by hydrostatic- and hydrodynamic-like forces. Here we investigate a new class of granular interactions: rapid intrusions by objects that change shape (self-deform) through passive and active means. Systematic studies of a simple spring-mass robot jumping on dry granular media reveal that jumping performance is explained by an interplay of nonlinear frictional and hydrodynamic drag as well as induced added mass (unaccounted by traditional intrusion models) characterized by a rapidly solidified region of grains accelerated by the foot. A model incorporating these dynamics reveals that added mass degrades the performance of certain self-deformations owing to a shift in optimal timing during push-off. Our systematic robophysical experiment reveals both new soft-matter physics and principles for robotic self-deformation and control, which together provide principles of movement in deformable terrestrial environments.
Correlation between dichromatic colour vision and jumping performance in horses.
Spaas, Julie; Helsen, Werner F; Adriaenssens, Maurits; Broeckx, Sarah; Duchateau, Luc; Spaas, Jan H
2014-10-01
There is general agreement that horses have dichromatic colour vision with similar capabilities to human beings with red-green colour deficiencies. However, whether colour perception has an impact on equine jumping performance and how pronounced the colour stimulus might be for a horse is unknown. The present study investigated the relationship between the colour of the fences (blue or green) and the show jumping performance of 20 horses ridden by two riders using an indoor and outdoor set of green and blue fences. In the indoor arena, significantly more touches and faults were made on blue fences in comparison to green fences (median difference of 2.5 bars). When only touched bars were included, a significant median difference of one bar was found. Mares (n = 4) demonstrated more faults and had a significantly greater difference in touches and faults between the two colours than male horses (n = 16). Repeating the same experiment with eight horses in an outdoor grass arena revealed no significant differences between the two colours. In order to draw any definite conclusions, more research concerning the colour perception, influence of contrast with the arena surface and sex of horse is required.
Dynamic control of droplet jumping by tailoring nanoparticle concentrations
Hao, Chonglei; Zhou, Yang; Zhou, Xiaofeng; Che, Lufeng; Chu, Baojin; Wang, Zuankai
2016-07-01
The dynamic impact behavior of droplets from solid surfaces has attracted increasing interest, especially propelled by the advances in the bio-inspired interfacial materials. In this work, we investigate the impact and bouncing dynamics of ethylene glycol droplets containing silica nanoparticles on superhydrophobic surfaces (SHS). We find that the rebounding of droplets from SHS is highly dependent on the impact velocity and suspension concentrations. By increasing the impact velocity or suspension concentrations, the probability of droplet bouncing from SHS is greatly reduced. The presence of nanoparticles can significantly increase the viscous energy dissipation inside the liquid droplets, therefore suppressing the jumping from surfaces. Based on the energy dissipation characterization, we also find the critical concentration to determine the manifestation of the viscous effect, above which the liquid suspensions exhibit non-Newtonian fluid properties. Our study provides an efficient approach to dynamically control the liquid jumping behaviors on SHS by tailoring the suspension concentrations. The insights learned from this study can be very useful in many industrial applications.
Prescription-induced jump distributions in multiplicative Poisson processes
Suweis, Samir; Porporato, Amilcare; Rinaldo, Andrea; Maritan, Amos
2011-06-01
Generalized Langevin equations (GLE) with multiplicative white Poisson noise pose the usual prescription dilemma leading to different evolution equations (master equations) for the probability distribution. Contrary to the case of multiplicative Gaussian white noise, the Stratonovich prescription does not correspond to the well-known midpoint (or any other intermediate) prescription. By introducing an inertial term in the GLE, we show that the Itô and Stratonovich prescriptions naturally arise depending on two time scales, one induced by the inertial term and the other determined by the jump event. We also show that, when the multiplicative noise is linear in the random variable, one prescription can be made equivalent to the other by a suitable transformation in the jump probability distribution. We apply these results to a recently proposed stochastic model describing the dynamics of primary soil salinization, in which the salt mass balance within the soil root zone requires the analysis of different prescriptions arising from the resulting stochastic differential equation forced by multiplicative white Poisson noise, the features of which are tailored to the characters of the daily precipitation. A method is finally suggested to infer the most appropriate prescription from the data.
Visual perception in the brain of a jumping spider.
Menda, Gil; Shamble, Paul S; Nitzany, Eyal I; Golden, James R; Hoy, Ronald R
2014-11-03
Jumping spiders (Salticidae) are renowned for a behavioral repertoire that can seem more vertebrate, or even mammalian, than spider-like in character. This is made possible by a unique visual system that supports their stalking hunting style and elaborate mating rituals in which the bizarrely marked and colored appendages of males highlight their song-and-dance displays. Salticids perform these tasks with information from four pairs of functionally specialized eyes, providing a near 360° field of view and forward-looking spatial resolution surpassing that of all insects and even some mammals, processed by a brain roughly the size of a poppy seed. Salticid behavior, evolution, and ecology are well documented, but attempts to study the neurophysiological basis of their behavior had been thwarted by the pressurized nature of their internal body fluids, making typical physiological techniques infeasible and restricting all previous neural work in salticids to a few recordings from the eyes. We report the first survey of neurophysiological recordings from the brain of a jumping spider, Phidippus audax (Salticidae). The data include single-unit recordings in response to artificial and naturalistic visual stimuli. The salticid visual system is unique in that high-acuity and motion vision are processed by different pairs of eyes. We found nonlinear interactions between the principal and secondary eyes, which can be inferred from the emergence of spatiotemporal receptive fields. Ecologically relevant images, including prey-like objects such as flies, elicited bursts of excitation from single units.
THE INFLUENCE OF MUSICAL CADENCE INTO AQUATIC JUMPING JACKS KINEMATICS
Directory of Open Access Journals (Sweden)
Mário J. Costa
2011-12-01
Full Text Available The aim of this study was to analyze the relationships between the head-out aquatic exercise "Jumping jacks" kinematics and the musical cadence in healthy and fit subjects. Five young women, with at least one year of experience conducting head- out aquatic programs were videotaped in the frontal plane, with a pair of cameras providing a double projection (above and below the water surface. Subjects performed an incremental protocol of five bouts (120 b·min-1, 135 b·min-1, 150 b·min-1, 165 b·min-1 and 180 b·min-1 with 16 full cycles of the "Jumping jacks" exercise. Data processing and calculation of upper limbs' (i.e. hands, lower limbs' (i.e. feet and center of mass' 2D linear velocity and displacement were computed with the software Ariel Performance Analysis System and applying the 2D-DLT algorithm. Subjects decreased the cycle period during the incremental protocol. Significant and negative relationships with the musical cadence were verified for the center of mass and upper limbs vertical displacement. On the other hand, for the lower limbs lateral velocity, a significant and positive relationship was observed. It is concluded that expert and fit subjects increase the lower limb's velocity to maintain the range of motion, while the upper limb's displacement is reduced to coupe the music cadence.
Keeping your eye on the rail: gaze behaviour of horse riders approaching a jump.
Hall, Carol; Varley, Ian; Kay, Rachel; Crundall, David
2014-01-01
The gaze behaviour of riders during their approach to a jump was investigated using a mobile eye tracking device (ASL Mobile Eye). The timing, frequency and duration of fixations on the jump and the percentage of time when their point of gaze (POG) was located elsewhere were assessed. Fixations were identified when the POG remained on the jump for 100 ms or longer. The jumping skill of experienced but non-elite riders (n = 10) was assessed by means of a questionnaire. Their gaze behaviour was recorded as they completed a course of three identical jumps five times. The speed and timing of the approach was calculated. Gaze behaviour throughout the overall approach and during the last five strides before take-off was assessed following frame-by-frame analyses. Differences in relation to both round and jump number were found. Significantly longer was spent fixated on the jump during round 2, both during the overall approach and during the last five strides (priders who scored higher for jumping skill tended to fixate on the jump earlier (p = 0.07), when the horse was further from the jump (p = 0.09) and their first fixation on the jump was of a longer duration (p = 0.06). Trials with elite riders are now needed to further identify sport-specific visual skills and their relationship with performance. Visual training should be included in preparation for equestrian sports participation, the positive impact of which has been clearly demonstrated in other sports.
Immediate effects of different types of stretching exercises on badminton jump smash.
Jang, Hwi S; Kim, Daeho; Park, Jihong
2017-04-13
Since different types of stretching exercises may alter athletic performance, we compared the effects of three types of stretching exercises on badminton jump smash. Sixteen male collegiate badminton players performed one of three different stretching exercises in a counterbalanced order on different days. Static stretching had seven typical stretches, while dynamic stretching involved nine dynamic movements, and resistance dynamic stretching was performed with weighted vests and dumbbells. Before and after each stretching exercise, subjects performed 20 trials of jump smashes. Dependent measurements were the jump heights during jump smashes, velocities of jump-smashed shuttlecocks, and drop points of jump-smashed shuttlecocks. To test the effects of each stretching exercise, we performed mixed model ANOVAs and calculated between-time effect sizes (ES). Each stretching exercise improved the jump heights during jump smashes (type main effect: F2,75= 1.19, p=0.31; static stretching: 22.1%, pstretching: 30.1%, pstretching: 17.7%, p=0.03, ES: 0.98) and velocities of jump-smashed shuttlecocks (type main effect: F2,75= 2.18, p=0.12; static stretching: 5.7%, p=0.61, ES: 0.39; dynamic stretching: 3.4%, p=0.94, ES: 0.28; resistance dynamic stretching: 6%, p=0.50, ES: 0.66). However, there were no differences among the stretching exercises for any measurement. The drop point of jump-smashed shuttlecocks did not change (interaction: F2,75= 0.88, p=0.42). All stretching exercises improved badminton jump smash performance, but we could not determine the best protocol. Since badminton requires high-speed movement and explosive force, we suggest performing dynamic stretching or resistance dynamic stretching.
Markovic, Srdjan; Dragan, Mirkov; Nedeljkovic, Aleksandar; Jaric, Slobodan
2013-01-01
A number of studies based on maximum vertical jumps have presumed that the maximum jump height reveals the maximum power of lower limb muscles, as well as the tested muscle power output predicts the jumping performance. The objective of the study was to test the hypothesis that both the body size and countermovement depth confound the relationship between the muscle power output and performance of maximum vertical jumps. Sixty young and physically active males were tested on the maximum countermovement (CMJ) and squat jumps (SJ). The jumping performance (Hmax), peak (Ppeak) and the average power output (Pavg) during the concentric phase, countermovement depth (only in CMJ) and body mass as an index of body size were assessed. To assess the power-performance relationship, the correlations between Hmax with both Ppeak and Pavg were calculated without and with controlling for the effects of body mass, as well as for the countermovement depth. The results revealed moderate power-performance relationships (range 0.55
Márquez, Gonzalo; Aguado, Xavier; Alegre, Luis M; Lago, Angel; Acero, Rafael M; Fernández-del-Olmo, Miguel
2010-08-01
After repeated jumps over an elastic surface (e.g. a trampoline), subjects usually report a strange sensation when they jump again overground (e.g. they feel unable to jump because their body feels heavy). However, the motor and sensory effects of exposure to an elastic surface are unknown. In the present study, we examined the motor and perceptual effects of repeated jumps over two different surfaces (stiff and elastic), measuring how this affected maximal countermovement vertical jump (CMJ). Fourteen subjects participated in two counterbalanced sessions, 1 week apart. Each experimental session consisted of a series of maximal CMJs over a force plate before and after 1 min of light jumping on an elastic or stiff surface. We measured actual motor performance (height jump and leg stiffness during CMJ) and how that related to perceptual experience (jump height estimation and subjective sensation). After repeated jumps on an elastic surface, the first CMJ showed a significant increase in leg stiffness (P < or = 0.01), decrease in jump height (P < or = 0.01) increase in perceptual misestimation (P < or = 0.05) and abnormal subjective sensation (P < or = 0.001). These changes were not observed after repeated jumps on a rigid surface. In a complementary experiment, continuous surface transitions show that the effects persist across cycles, and the effects over the leg stiffness and subjective experience are minimized (P < or = 0.05). We propose that these aftereffects could be the consequence of an erroneous internal model resulting from the high vertical forces produced by the elastic surface.
Effects of a Low-Load Gluteal Warm-Up on Explosive Jump Performance
Directory of Open Access Journals (Sweden)
Comyns Thomas
2015-06-01
Full Text Available The purpose of this study was to investigate the effects of a low-load gluteal warm-up protocol on countermovement and squat jump performance. Research by Crow et al. (2012 found that a low-load gluteal warm-up could be effective in enhancing peak power output during a countermovement jump. Eleven subjects performed countermovement and squat jumps before and after the gluteal warm-up protocol. Both jumps were examined in separate testing sessions and performed 30 seconds, and 2, 4, 6 & 8 minutes post warm-up. Height jumped and peak ground reaction force were the dependent variables examined in both jumps, with 6 additional variables related to fast force production being examined in the squat jump only. All jumps were performed on a force platform (AMTI OR6-5. Repeated measures analysis of variance found a number of significant differences (p ≤ 0.05 between baseline and post warm-up scores. Height jumped decreased significantly in both jumps at all rest intervals excluding 8 minutes. Improvement was seen in 7 of the 8 recorded SJ variables at the 8 minute interval. Five of these improvements were deemed statistically significant, namely time to peak GRF (43.0%, and time to the maximum rate of force development (65.7% significantly decreased, while starting strength (63.4%, change of force in first 100 ms of contraction (49.1% and speed strength (43.6% significantly increased. The results indicate that a gluteal warm-up can enhance force production in squat jumps performed after 8 minutes recovery. Future research in this area should include additional warm-up intervention groups for comparative reasons.
Julian Bergmann; Andreas Kramer; Markus Gruber
2013-01-01
Postactivation potentiation (PAP) has been defined as the increase in twitch torque after a conditioning contraction. The present study aimed to investigate the effectiveness of hops as conditioning contractions to induce PAP and increase performance in subsequent maximal drop jumps. In addition, we wanted to test if and how PAP can contribute to increases in drop jump rebound height. Twelve participants performed 10 maximal two-legged hops as conditioning contractions. Twitch peak torques of...
The acute effects of dynamic and ballistic stretching on vertical jump height, force, and power.
Jaggers, Jason R; Swank, Ann M; Frost, Karen L; Lee, Chong D
2008-11-01
Stretching before performance is a common practice among athletes in hopes of increasing performance and reducing the risk of injury. However, cumulative results indicate a negative impact of static stretching and proprioceptive neuromuscular facilitation (PNF) on performance; thus, there is a need for evaluating other stretching strategies for effective warm-up. The purpose of this study was to compare the differences between two sets of ballistic stretching and two sets of a dynamic stretching routine on vertical jump performance. Twenty healthy male and female college students between the ages of 22 and 34 (24.8 +/- 3 years) volunteered to participate in this study. All subjects completed three individual testing sessions on three nonconsecutive days. On each day, the subjects completed one of three treatments (no stretch, ballistic stretch, and dynamic stretch). Intraclass reliability was determined using the data obtained from each subject. A paired samples t-test revealed no significant difference in jump height, force, or power when comparing no stretch with ballistic stretch. A significant difference was found on jump power when comparing no stretch with dynamic stretch, but no significant difference was found for jump height or force. Statistics showed a very high reliability when measuring jump height, force, and power using the Kistler Quattro Jump force plate. It seems that neither dynamic stretching nor ballistic stretching will result in an increase in vertical jump height or force. However, dynamic stretching elicited gains in jump power poststretch.
The Impact of Jumps and Leverage in Forecasting Co-Volatility
M. Asai (Manabu); M.J. McAleer (Michael)
2015-01-01
markdownabstract__Abstract__ The paper investigates the impact of jumps in forecasting co-volatility, accommodating leverage effects. We modify the jump-robust two time scale covariance estimator of Boudt and Zhang (2013) such that the estimated matrix is positive definite. Using this approach we
The Impact of Jumps and Leverage in Forecasting Co-Volatility
M. Asai (Manabu); M.J. McAleer (Michael)
2015-01-01
markdownabstract__Abstract__ The paper investigates the impact of jumps in forecasting co-volatility, accommodating leverage effects. We modify the jump-robust two time scale covariance estimator of Boudt and Zhang (2013)such that the estimated matrix is positive definite. Using this approach we ca
Directory of Open Access Journals (Sweden)
Emilio J. Martínez-López
2012-12-01
Full Text Available The purpose of this study was to examine the effects of eight- week (2 days/week training periods of plyometric exercises (PT and neuromuscular electrostimulation (EMS on jump height in young athletes. Squat jump (SJ, counter movement jump (CMJ and drop jump (DJ were performed to assess the effects of the training protocols 98 athletes (100 & 200m and 100m & 110m hurdles voluntarily took part in this study, 51 males (52% and 47 females (48%, 17.91 ± 1.42 years old, and 5.16 ± 2.56 years of training experience. The participants were randomly assigned to four different groups according to the frequency and the timing of the stimulation. Analysis of covariance was used to analyze the effects of every training program on jump height. Our findings suggest that compared to control (Plyometrics (PT only, the combination of 150Hz EMS + PT simultaneously combined in an 8 week (2days/week training program, we could observe significant jump height improvements in the different types of strength: explosive, explosive-elastic, and explosive-elastic-reactive. The combination of PT after < 85 Hz EMS did not show any jump height significant increase in sprinters. In conclusion, an eight week training program (with just two days per week of EMS combined with plyometric exercises has proven useful for the improvement of every kind of vertical jump ability required for sprint and hurdles disciplines in teenage athletes
60 FR 56561 - Jump Creek Water Quality Planning Project Owyhee County
1995-11-09
... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF AGRICULTURE Natural Resources Conservation Service Jump Creek Water Quality Planning Project Owyhee County AGENCY... impact statement is not being prepared for the Jump Creek Water Quality Planning Project, Owyhee...
Measurement of L(III) Subshell Absorption Jump Parameters of Hafnium.
Cengiz, E; Saritas, N; Dogan, M; Koksal, O K; Karabulut, K; Apaydin, G; Tirasoglu, E
2015-12-01
The L(III) subshell absorption jump ratio and jump factor of hafnium have been measured using two different ways which are X-ray attenuation method and Energy Dispersive X-ray Fluorescence technique. The results obtained both ways have been compared with theoretical values. They are in good agreement with each other.
Power-Velocity Characteristics and Jumping Abilities in Male Combat Athletes
Directory of Open Access Journals (Sweden)
Buśko Krzysztof
2016-09-01
Full Text Available Purpose. The aim of the study was to examine differences in power-velocity characteristics, and the maximal power and height of rise of the body’s centre of mass, measured in the counter-movement jump (CMJ and the spike jump (SPJ, between judoists, boxers and taekwondo athletes.
Limit theorems for vertex-reinforced jump processes on regular trees
Collevecchio, Andrea
2009-01-01
Consider a vertex-reinforced jump process defined on a regular tree, where each vertex has exactly $b$ children, with $b \\ge 3$. We prove the strong law of large numbers and the central limit theorem for the distance of the process from the root. Notice that it is still unknown if vertex-reinforced jump process is transient on the binary tree.
Critical size ratio for coalescence-induced droplet jumping on superhydrophobic surfaces
Wang, Kai; Li, Ruixin; Liang, Qianqing; Jiang, Rui; Zheng, Yi; Lan, Zhong; Ma, Xuehu
2017-08-01
The mechanism of coalescence-induced droplet jumping on superhydrophobic surfaces has been relatively well-established over the years. Most of the related studies are only considering the coalescence process of equal-sized water droplets. However, the coalescence of droplets with different sizes is actually more frequently encountered and the effect of the size ratio on droplet jumping is very crucial to the hydrodynamics of this process. In this work, the effect of the initial droplet size ratio on coalescence-induced jumping of two water droplets is investigated experimentally and numerically. For the previously reported jumping droplet sizes (˜1-100 μm), it is found that the critical droplet size ratio below which the jumping does not occur is about 0.56. The results agree well with the experimental data as the size ratios of observed jumping events collapse into the predicted jumping regime. These findings will gain insights into droplet jumping which has great potential in a number of industrial processes.
Squat Jump Performance during Growth in Both Sexes: Comparison with Cycling Power
Dore, Eric; Bedu, Mario; Van Praagh, Emmanuel
2008-01-01
The purpose of this cross-sectional study was to investigate leg muscle power and compare two activities (jumping and cycling) in 383 girls and 407 boys ages 9-19 years. Results in anthropometric characteristics and jumping performance were comparable until midadolescence, and sex differences were observed. Lean leg volume (LLV) was the reason for…
Jump Rope Skills for Fun and Fitness in Grades K-12
Michiels Hernandez, Barbara L.; Gober, Donna; Boatwright, Douglas; Strickland, George
2009-01-01
A jump rope is a remarkable piece of exercise equipment. It is inexpensive and easy to store, and it can be used by a wide variety of age groups to improve cardiovascular fitness, increase agility, and tone the body's muscles all at the same time. Consequently, the teaching of jump rope skills is highly suitable for physical education classes in…
Segmental and Kinetic Contributions in Vertical Jumps Performed with and without an Arm Swing
Feltner, Michael E.; Bishop, Elijah J.; Perez, Cassandra M.
2004-01-01
To determine the contributions of the motions of the body segments to the vertical ground reaction force ([F.sub.z]), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm…
Influence of a Horizontal Approach on the Mechanical Output during Drop Jumps
Ruan, Mianfang; Li, Li
2008-01-01
This study investigated the influence of a horizontal approach to mechanical output during drop jumps. Participants performed drop jumps from heights of 15, 30, 45, and 60 cm with zero, one, two, and three approach steps. The peak summed power during the push-off phase changed quadratically across heights (6.2 [plus or minus] 0.3, 6.7 [plus or…
Cooperative jump motions of jammed particles in a one-dimensional periodic potential.
Sakaguchi, Hidetsugu
2009-12-01
Cooperative jump motions are studied for mutually interacting particles in a one-dimensional periodic potential. The diffusion constant for the cooperative motion in systems including a small number of particles is numerically calculated and it is compared with theoretical estimates. We find that the size distribution of the cooperative jump motions obeys an exponential law in a large system.
Cooperative jump motions of jammed particles in a one-dimensional periodic potential
Sakaguchi, Hidetsugu
2009-01-01
Cooperative jump motions are studied for mutually interacting particles in a one-dimensional periodic potential. The diffusion constant for the cooperative motion in systems including a small number of particles is numerically calculated and it is compared with theoretical estimates. We find that the size distribution of the cooperative jump motions obeys an exponential law in a large system.
Physically based sound synthesis and control of jumping sounds on an elastic trampoline
DEFF Research Database (Denmark)
Turchet, Luca; Pugliese, Roberto; Takala, Tapio
2013-01-01
This paper describes a system to interactively sonify the foot-floor contacts resulting from jumping on an elastic trampoline. The sonification was achieved by means of a synthesis engine based on physical models reproducing the sounds of jumping on several surface materials. The engine was contr...... on multi-sensory perception involving the auditory and the foot- haptic modalities....
Effects of six warm-up protocols on sprint and jump performance.
Vetter, Rheba E
2007-08-01
The purpose of this study was to compare the effects of 6 warm-up protocols, with and without stretches, on 2 different power maneuvers: a 30-m sprint run and a vertical countermovement jump (CJ). The 6 protocols were: (a) walk plus run (WR); (b) WR plus exercises including small jumps (EJ); (c) WR plus dynamic active stretch plus exercises with small jumps (DAEJ); (d) WR plus dynamic active stretch (DA); (e) WR plus static stretch plus exercises with small jumps (SSEJ); and (f) WR plus static stretch (SS). Twenty-six college-age men (n = 14) and women (n = 12) performed each of 6 randomly ordered exercise routines prior to randomly ordered sprint and vertical jump field tests; each routine and subsequent tests were performed on separate days. A 2 x 6 repeated measures analysis of variance revealed a significant overall linear trend (p hoc analysis pairwise comparisons showed the WR protocol produced higher jumps than did SS (p = 0.003 protocols on sprint run performance (p > or = 0.05). No significant interaction occurred between gender and protocol. There were significant differences between men and women on CJ and sprint trials; as expected, in general men ran faster and jumped higher than the women did. The data indicate that a warm-up including static stretching may negatively impact jump performance, but not sprint time.
Exertion of forces by children performing a free-style jump
Moes, C.C.M.; Visser, R.J.
1998-01-01
This research project focuses on the force characteristics and force/time relationships of loads exerted by jumping children. The current study is an experimental research into children jumping on both hard and soft substrates. The hard substrate is obtained by using a force plate. For the soft subs
Gheller, Rodrigo G; Dal Pupo, Juliano; Ache-Dias, Jonathan; Detanico, Daniele; Padulo, Johnny; dos Santos, Saray G
2015-08-01
This study aimed to analyze the effect of different knee starting angles on jump performance, kinetic parameters, and intersegmental coupling coordination during a squat jump (SJ) and a countermovement jump (CMJ). Twenty male volleyball and basketball players volunteered to participate in this study. The CMJ was performed with knee flexion at the end of the countermovement phase smaller than 90° (CMJ(90)), and in a preferred position (CMJ(PREF)), while the SJ was performed from a knee angle of 70° (SJ(70)), 90° (SJ(90)), 110° (SJ(110)), and in a preferred position (SJ(PREF)). The best jump performance was observed in jumps that started from a higher squat depth (CMJ(power was observed in the SJ(110) and CMJ(>90). Analysis of continuous relative phase showed that thigh-trunk coupling was more in-phase in the jumps (CMJ and SJ) performed with a higher squat depth, while the leg-thigh coupling was more in-phase in the CMJ(>90) and SJ(PREF). Jumping from a position with knees more flexed seems to be the best strategy to achieve the best performance. Intersegmental coordination and jump performance (CMJ and SJ) were affected by different knee starting angles.
Inertia Matching Manipulability and Load Matching Optimization for Humanoid Jumping Robot
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Zhaohong Xu
2008-11-01
Full Text Available Human jumping motion includes stance phase, flight phase and landing impact phase. Jumping robot belongs to a variable constraints system because every phase has different constraint conditions. An unified dynamics equation during stance phase and flight phase is established based on floated-basis space. Inertia matching is used to analyze actuator/gear systems and select the optimum gear ratio based on the transmission performance between the torque produced at the actuator and the torque applied to the load. Load matching is an important index which affects jumping performance and reflects the capability of supporting a weight or mass. It also affects the distributing of the center of gravity (COG. Regarding jumping robot as a redundant manipulator with a load at end-effector, inertia matching can be applied to optimize load matching for jumping robot. Inertia matching manipulability and directional manipulability are easy to analyze and optimize the load matching parameters. A 5th order polynomial function is defined to plan COG trajectory of jumping motion, taking into account the constraint conditions of both velocity and acceleration. Finally, the numerical simulation of vertical jumping and experimental results show inertia matching is in direct proportion to jumping height, and inertia matching manipulability is a valid method to load matching optimization and conceptual design of robot.
Inter-segmental moment analysis characterises the partial correspondence of jumping and jerking
Cleather, Daniel J; Goodwin, Jon E; Bull, Anthony MJ
2014-01-01
The aim of this study was to quantify internal joint moments of the lower limb during vertical jumping and the weightlifting jerk in order to improve awareness of the control strategies and correspondence between these activities, and to facilitate understanding of the likely transfer of training effects. Athletic males completed maximal unloaded vertical jumps (n=12) and explosive push jerks at 40 kg (n=9). Kinematic data were collected using optical motion tracking and kinetic data via a force plate, both at 200 Hz. Joint moments were calculated using a previously described biomechanical model of the right lower limb. Peak moment results highlighted that sagittal plane control strategies differed between jumping and jerking (p0.05) possibly indicating a limit to the direct transferability of jerk performance to jumping. Ankle joint moments were poorly related to jump performance (p>0.05). Peak knee and hip moment generating capacity are important to vertical jump performance. The jerk appears to offer an effective strategy to overload joint moment generation in the knee relative to jumping. However, an absence of hip involvement would appear to make it a general, rather than specific, training modality in relation to jumping. PMID:22362089
DEFF Research Database (Denmark)
Bollerslev, Tim; Andersen, Torben G.; Diebold, Francis X.
A rapidly growing literature has documented important improvements in financial return volatility measurement and forecasting via use of realized variation measures constructed from high-frequency returns coupled with simple modeling procedures. Building on recent theoretical results in Barndorff...... bond yield, we find that jumps are both highly prevalent and distinctly less persistent than the continuous sample path variation process. Moreover, many jumps appear directly associated with specific macroeconomic news announcements. Separating jump from non-jump movements in a simple...... but sophisticated volatility forecasting model, we find that almost all of the predictability in daily, weekly, and monthly return volatilities comes from the non-jump component. Our results thus set the stage for a number of interesting future econometric developments and important financial applications...
Multiple Neuromas Cause Painful "Jumping Stump" in a Transfemoral Amputee: A Case Report.
Buntragulpoontawee, Montana; Pattamapaspong, Nuttaya; Tongprasert, Siam
2016-09-01
Painful "jumping stump" is an uncommon but very disturbing complication postamputation. This condition is one of the movement disorder entities resulting from peripheral nerve pathology, often known as "peripherally induced movement disorders." Previously case reports have been written about painful and nonpainful incidence of "jumping stump"; however, only the earliest "jumping stump" article in 1852 suspected that neuromas might influence the involuntary movement. In this study, we describe a 38-year-old man with bilateral transfemoral amputee who suffered from painful "jumping stump" with multiple neuromas confirmed by imaging. He was treated successfully by ultrasound-guided phenol injection into the sciatic neuroma stalks. The pathophysiology of jumping stump and its possible association with neuroma are briefly discussed.
Designing, Building, Measuring and Testing a Constant Equivalent Fall Height Terrain Park Jump
Petrone, Nicola; McNeil, James A; Hubbard, Mont
2016-01-01
Previous work has presented both a theoretical foundation for designing terrain park jumps that control landing impact and computer software to accomplish this task. US ski resorts have been reluctant to adopt this more engineered approach to jump design, in part due to questions of feasibility. The present study demonstrates this feasibility. It describes the design, construction, measurement and experimental testing of such a jump. It improves on previous efforts with more complete instrumentation, a larger range of jump distances, and a new method for combining jumper- and board-mounted accelerometer data to estimate equivalent fall height, a measure of impact severity. It unequivocally demonstrates the efficacy of the engineering design approach, namely that it is possible and practical to design and build free style terrain park jumps with landing surface shapes that control for landing impact as predicted by the theory.
Banerjee, Puja; Bagchi, Biman
2016-01-01
Molecular dynamics simulations of aqueous potassium nitrate solution reveal a highly complex rotational dynamics of nitrate ions where, superimposed on the expected continuous Brownian motion, are large amplitude angular jumps that are coupled to and at least partly driven by similar large amplitude jump motions in water molecules which are associated with change in the hydrogen bonded water molecule. These jumps contribute significantly to rotational and translational motions of these ions. We explore the detailed mechanism of these correlated (or, coupled) jumps and introduce a new time correlation function to decompose the coupled orientational- jump dynamics of solvent and solute in the aqueous electrolytic solution. Time correlation function provides for the unequivocal determination of the time constant involved in orientational dynamics originating from making and breaking of hydrogen bonds. We discover two distinct mechanisms-both are coupled to density fluctuation but are of different types.
Increased jump height with an external focus due to enhanced lower extremity joint kinetics.
Wulf, Gabriele; Dufek, Janet S
2009-10-01
Individuals jump higher when they adopt an external focus of attention, relative to an internal focus or no focus of attention (G. Wulf, T. Zachry, C. Granados, & J. S. Dufek, 2007). In the present study, the authors determined the underlying cause of this effect. Participants performed a vertical jump-and-reach task for (a) an external focus condition (i.e., participants focused on the rungs of a Vertec [Perform Better, Cranston, RI] measurement device that they touched) and (b) an internal focus condition (i.e., participants focused on the finger with which they touched the rungs). Participants' jump height, center-of-mass displacement, jump impulse, and lower extremity joint moments were greater with an external focus compared with an internal focus. These results suggest that participants jump higher by producing greater forces when they adopt an external focus. This finding adds to evidence that an external focus facilitates the production of effective and efficient movement patterns.
Body acceleration distribution and O2 uptake in humans during running and jumping
Bhattacharya, A.; Mccutcheon, E. P.; Shvartz, E.; Greenleaf, J. E.
1980-01-01
The distribution of body acceleration and associated oxygen uptake and heart rate responses are investigated in treadmill running and trampoline jumping. Accelerations in the +Gz direction were measured at the lateral ankle, lumbosacral region and forehead of eight young men during level treadmill walking and running at four speeds and trampoline jumping at four heights, together with corresponding oxygen uptake and heart rate. With increasing treadmill speed, peak acceleration at the ankle is found always to exceed that at the back and forehead, and acceleration profiles with higher frequency components than those observed during jumping are observed. Acceleration levels are found to be more uniformly distributed with increasing height in jumping, although comparable oxygen uptake and heat rates are obtained. Results indicate that the magnitude of the biomechanical stimuli is greater in trampoline jumping than in running, which finding could be of use in the design of procedures to avert deconditioning in persons exposed to weightlessness.
A Shape Memory Alloy-Actuated Bio-inspired Mesoscale Jumping Robot
Directory of Open Access Journals (Sweden)
Thanhtam Ho
2012-09-01
Full Text Available Jumping may be considered to be quite a useful means of mobile robot locomotion, but acquiring a stable landing has been a difficult problem. This paper reports on the design, analysis, simulation and experiments of a mesoscale jumping robot that is capable of stable landing. A jumping mechanism inspired by jumping insects is introduced and an actuation scheme using only one shape memory alloy (SMA spring is described. Experimental results show that a robot with a 17 gram weight and 13 cm diameter can jump forward as far as 1.2 times its body diameter and vertically as high as 1.5 times its body diameter. In addition, the robot is able to land in a stable manner and recover its initial posture after landing.
Gender differences in triple jump phase ratios and arm swing motion of international level athletes
Directory of Open Access Journals (Sweden)
Vassilios Panoutsakopoulos
2016-12-01
Full Text Available Background: Female triple jumping is a relatively new athletics event. A limited number of researchers have focused on comparing male and female jumpers competing in international events, resulting in scarce findings in the literature regarding gender differences of the determinants of triple jump performance. Objective: The aim of the study was to examine the possible gender differences in the approach step characteristics, the spatiotemporal parameters of the separate phases of the triple jump as performed by athletes participating in sub-elite international events. Methods: The male and female participants of the 2015 European Team Championships triple jump event were recorded with a panning video camera. Approach speed was measured using photocells. Kinematical parameters were extracted using the APAS WIZARD 13.3.0.3 software. The relationships between the examined parameters and the actual triple jump performance were examined with Pearson's correlation analysis. Repeated measures ANOVA and chi-square statistical tests were run to examine the significance of the differences between genders. Results: Approach speed significantly correlated with the actual jumping distance in both males and females (p < .05. Significant gender differences (p < .05 existed concerning basic kinematical parameters. Men were found to have larger average horizontal speed of the 11 m to 1 m segment of the final approach, step length of the final six steps of the approach, step frequency of the final two steps, actual phase distances and percentage distribution of the step. Women, unlike men, used solely single arm swing techniques. No athlete executed the jump using a jump dominated technique. Conclusions: Gender differences in triple jump performance lies upon the kinematical parameters of the final two steps of the approach, the length of the step phase and the support time for the jump. The technique elements of the penultimate step are suggested to
Directory of Open Access Journals (Sweden)
Yong-In Ju
Full Text Available Substantial evidence from animal studies indicates that jumping increases bone mass and strength. However, most studies have focused on the take-off, rather than the landing phase of jumps. Thus, we compared the effects of landing and upward jump impact on trabecular bone mass and microarchitecture. Male Wistar rats aged 10 weeks were randomly assigned to the following groups: sedentary control (CON, 40-cm upward jumps (40UJ; 40-cm drop jumps (40DJ; and 60-cm drop jumps (60DJ (n = 10 each. The upward jump protocol comprised 10 upward jumps/day, 5 days/week for 8 weeks to a height of 40 cm. The drop jump protocol comprised dropping rats from a height of 40 or 60 cm at the same frequency and time period as the 40UJ group. Trabecular bone mass, architecture, and mineralization at the distal femoral metaphysis were evaluated using microcomputed tomography. Ground reaction force (GRF was measured using a force platform. Bone mass was significantly higher in the 40UJ group compared with the DJ groups (+49.1% and +28.3%, respectively, although peak GRF (-57.8% and -122.7%, respectively and unit time force (-21.6% and -36.2%, respectively were significantly lower in the 40UJ group. These results showed that trabecular bone mass in growing rats is increased more effectively by the take-off than by the landing phases of jumps and suggest that mechanical stress accompanied by muscle contraction would be more important than GRF as an osteogenic stimulus. However, the relevance of these findings to human bone physiology is unclear and requires further study.
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Komura Taku
2007-06-01
Full Text Available Abstract Background The purpose of this study was to investigate the coordination strategy of maximal-effort horizontal jumping in comparison with vertical jumping, using the methodology of computer simulation. Methods A skeletal model that has nine rigid body segments and twenty degrees of freedom was developed. Thirty-two Hill-type lower limb muscles were attached to the model. The excitation-contraction dynamics of the contractile element, the tissues around the joints to limit the joint range of motion, as well as the foot-ground interaction were implemented. Simulations were initiated from an identical standing posture for both motions. Optimal pattern of the activation input signal was searched through numerical optimization. For the horizontal jumping, the goal was to maximize the horizontal distance traveled by the body's center of mass. For the vertical jumping, the goal was to maximize the height reached by the body's center of mass. Results As a result, it was found that the hip joint was utilized more vigorously in the horizontal jumping than in the vertical jumping. The muscles that have a function of joint flexion such as the m. iliopsoas, m. rectus femoris and m. tibialis anterior were activated to a greater level during the countermovement in the horizontal jumping with an effect of moving the body's center of mass in the forward direction. Muscular work was transferred to the mechanical energy of the body's center of mass more effectively in the horizontal jump, which resulted in a greater energy gain of the body's center of mass throughout the motion. Conclusion These differences in the optimal coordination strategy seem to be caused from the requirement that the body's center of mass needs to be located above the feet in a vertical jumping, whereas this requirement is not so strict in a horizontal jumping.
Effects of fatigue of plantarflexors on control and performance in vertical jumping.
Bobbert, Maarten F; van der Krogt, Marjolein M; van Doorn, Hemke; de Ruiter, Cornelis J
2011-04-01
We investigated the effects of a mismatch between control and musculoskeletal properties on performance in vertical jumping. Six subjects performed maximum-effort vertical squat jumps before (REF) and after the plantarflexors of the right leg had been fatigued (FAT) while kinematic data, ground reaction forces, and EMG of leg muscles were collected. Inverse dynamics was used to calculate the net work at joints, and EMG was rectified and smoothed to obtain the smoothed rectified EMG (SREMG). The jumps of the subjects were also simulated with a musculoskeletal model comprising seven body segments and 12 Hill-type muscles, and having as only input muscle stimulation. Jump height was approximately 6 cm less in FAT jumps than in REF jumps. In FAT jumps, peak SREMG level was reduced by more than 35% in the right plantarflexors and by approximately 20% in the right hamstrings but not in any other muscles. In FAT jumps, the net joint work was reduced not only at the right ankle (by 70%) but also at the right hip (by 40%). Because the right hip was not spanned by fatigued muscles and the reduction in SREMG of the right hamstrings was relatively small, this indicated that the reduction in performance was partly due to a mismatch between control and musculoskeletal properties. The differences between REF and FAT jumps of the subjects were confirmed and explained by the simulation model. Reoptimization of control for the FAT model caused performance to be partly restored by approximately 2.5 cm. The reduction in performance in FAT jumps was partly due to a mismatch between control and musculoskeletal properties.
Directory of Open Access Journals (Sweden)
Matheus Machado Gomes
2009-09-01
Full Text Available The aim of this study was to compare jump height and kinetic and kinematic com-ponents of countermovement vertical jumps between soccer and basketball players performed in two different arm swing conditions: with arm swing (WAS and without arm swing (NAS. Nine basketball players (21.2 ± 2.9 years; 101.64 ± 14.58 kg; 1.95 ± 0.06 m and nine soccer players (18.2 ± 0.7 years; 77.4 ± 7.58 kg; 1.81 ± 0.07 m performed 12 maximal countermo-vement vertical jumps, including 6 WAS jumps and 6 NAS jumps, on a force platform that recorded the ground reaction force (GRF. The vertical component of the GRF was used to estimate jump height and to calculate the kinematic (duration of eccentric phase, duration of concentric phase, and maximal downward displacement of center of mass and kinetic variables (mean power during the eccentric phase, mean power during the concentric, peak power, and peak force. The results showed no differences in jump height or in kinematic or kinetic variables between basketball and soccer players. In addition, the results showed that the participants of the two groups jumped higher in the WAS condition (0.41 m than in the NAS condition (0.36 m because of a higher peak power (WAS=276.8 W/kg0.67 and NAS=241.3 W/kg0.67 and a longer concentric phase duration (WAS=0.20 s/m0.5 and NAS=0.19 s/m0.5 during WAS jump. These results indicate that the basketball and soccer players studied here showed similar performance and the same kinematic and kinetic pattern in maximal vertical jumps and were comparably affected by the use of arm swing.
Double large Barkhausen jump in soft/soft composite microwires
Energy Technology Data Exchange (ETDEWEB)
Infante, G; Badini-Confalonieri, G A; Real, R P del; Vazquez, M, E-mail: mvazquez@icmm.csic.e [Materials Science Institute of Madrid, CSIC, 28049 Madrid (Spain)
2010-09-01
The magnetic properties of double layer microwires consisting of a soft FeSiBP amorphous core, an intermediate non-magnetic glass spacer and a softer FeNi outer shell have been investigated. As in the case of other magnetostatically coupled two-phase systems, the hysteresis loops are characterized by two well-defined Barkhausen jumps corresponding each to the magnetization reversal of the individual phases, separated by a plateau. The strong dipolar interaction that leads to the appearance of the plateau is investigated in terms of the microwire geometry. It is shown that this source of coupling is capable of increasing up to one order of magnitude the switching field of the Fe-rich core. Thus, magnetic bistability can be effectively controlled in these kinds of composite wires.
Simulations on the AGS horizontal tune jump mechanism
Energy Technology Data Exchange (ETDEWEB)
Lin,F.; Huang, H.; Luccio, A. U.; Roser, T.
2009-05-04
A new horizontal tune jump mechanism has been proposed to overcome the horizontal intrinsic resonances and preserve the polarization of the proton beam in the Alternating Gradient Synchrotron (AGS) during the energy ramp. An adiabatic change of the AGS lattice is needed to avoid the emittance growth in both horizontal and vertical planes, as the emittance growth can deteriorate the polarization of the proton beam. Two critical questions are necessary to be answered: how fast can the lattice be changed and how much emittance growth can be tolerated from both optics and polarization points of view? Preliminary simulations, using a realistic AGS lattice and acceleration rate, have been carried out to give a first glance of this mechanism. Results with different optics are presented in this paper.
On the propagation of jump discontinuities in relativistic cosmology
Van Elst, H; Schmidt, B G; Elst, Henk van; Ellis, George F R; Schmidt, Bernd G
2000-01-01
A recent dynamical formulation at derivative level $\\ptl^{3}g$ for fluid spacetime geometries $({\\cal M}, {\\bf g}, {\\bf u})$, that employs the concept of evolution systems in first-order symmetric hyperbolic format, implies the existence in the Weyl curvature branch of a set of timelike characteristic 3-surfaces associated with propagation speed $| v | = \\sfrac{1}{2}$ relative to fluid-comoving observers. We show it is the physical role of the constraint equations to prevent realisation of jump discontinuities in the derivatives of the related initial data so that Weyl curvature modes propagating along these 3-surfaces cannot be activated. In addition we introduce a new, illustrative first-order symmetric hyperbolic evolution system at derivative level $\\ptl^{2}g$ for baryotropic perfect fluid cosmological models that are invariant under the transformations of an Abelian $G_{2}$ isometry group.
Quantum Noise, Bits and Jumps: Uncertainties, Decoherence, Trajectories and Filtering
Belavkin, V P
2001-01-01
It is shown that many dissipative phenomena of "old" quantum mechanics which appeared 100 years ago in the form of the statistics of quantum thermal noise and quantum spontaneous jumps, have never been explained by the "new" conservative quantum mechanics discovered 75 years ago by Heisenberg and Schroedinger. This led to numerous quantum paradoxes which are reconsidered in this paper. The development of quantum measurement theory, initiated by von Neumann, indicated a possibility for resolution of this interpretational crisis by divorcing the algebra of the dynamical generators from the algebra of the actual observables. It is shown that within this approach quantum causality can be rehabilitated in the form of a superselection rule for compatibility of past observables with the potential future. This rule, together with the self-compatibility of measurements insuring the consistency of histories, is called the nondemolition principle. The application of this causality condition in the form of the dynamical ...
Reversible jump Markov chain Monte Carlo for deconvolution.
Kang, Dongwoo; Verotta, Davide
2007-06-01
To solve the problem of estimating an unknown input function to a linear time invariant system we propose an adaptive non-parametric method based on reversible jump Markov chain Monte Carlo (RJMCMC). We use piecewise polynomial functions (splines) to represent the input function. The RJMCMC algorithm allows the exploration of a large space of competing models, in our case the collection of splines corresponding to alternative positions of breakpoints, and it is based on the specification of transition probabilities between the models. RJMCMC determines: the number and the position of the breakpoints, and the coefficients determining the shape of the spline, as well as the corresponding posterior distribution of breakpoints, number of breakpoints, coefficients and arbitrary statistics of interest associated with the estimation problem. Simulation studies show that the RJMCMC method can obtain accurate reconstructions of complex input functions, and obtains better results compared with standard non-parametric deconvolution methods. Applications to real data are also reported.
The Effect of Jump on Evaluating Natural Resource Investments
Institute of Scientific and Technical Information of China (English)
Yang Haisheng; Zhou Yongzhang; Wang Shugong
2004-01-01
The evaluation of mining and other natural resource projects is made particularly difficult by the high degree of uncertainty attaching to output prices.It is shown that the techniques of continuous time arbitrage and stochastic control theory may be used not only to value such projects but also to determine the optimal policies for developing managing. This paper describes a model for evaluating natural resource investments under uncertainty from a new perspective. The previous works in this field mostly regard the movements of natural resource prices as a continuous GBM process, which pays few attentions to the shock of unexpected bad news. Our model provides the first theoretical method to analyze the impact of such "jump" on investment decisions. It concludes that the more frequently bad news happens,the earlier a project will be invested.
Non-Markovian Quantum Jumps in Excitonic Energy Transfer
Rebentrost, Patrick; Aspuru-Guzik, Alan
2009-01-01
We utilize the novel non-Markovian quantum jump (NMQJ) approach to stochastically simulate exciton dynamics derived from a time-convolutionless master equation. For relevant parameters and time scales, the time-dependent, oscillatory decoherence rates can have negative regions, a signature of non-Markovian behavior and of the revival of coherences. This can lead to non-Markovian population beatings for a dimer system at room temperature. We show that strong exciton-phonon coupling to low frequency modes can considerably modify transport properties. We observe increased exciton transport, which can be seen as an extension of recent environment-assisted quantum transport (ENAQT) concepts to the non-Markovian regime. Within the NMQJ method, the Fenna-Matthew-Olson protein is investigated as a prototype for larger photosynthetic complexes.
GENETIC PROGRAMMING TO PREDICT SKI-JUMP BUCKET SPILLWAY SCOUR
Institute of Scientific and Technical Information of China (English)
AZAMATHULLA H. MD; GHANI A. AB; ZAKARIA N. A; LAI S. H; CHANG C. K; LEOW C. S; ABUHASAN Z
2008-01-01
Researchers in the past had noticed that application of Artificial Neural Networks (ANN) in place of conventional statistics on the basis of data mining techniques predicts more accurate results in hydraulic predictions. Mostly these works pertained to applications of ANN. Recently, another tool of soft computing, namely, Genetic Programming (GP) has caught the attention of researchers in civil engineering computing. This article examines the usefulness of the GP based approach to predict the relative scour depth downstream of a common type of ski-jump bucket spillway. Actual field measurements were used to develop the GP model. The GP based estimations were found to be equally and more accurate than the ANN based ones, especially, when the underlying cause-effect relationship became more uncertain to model.
Berry phase jumps and giant nonreciprocity in Dirac quantum dots
Rodriguez-Nieva, Joaquin F.; Levitov, Leonid S.
2016-12-01
We predict that a strong nonreciprocity in the resonance spectra of Dirac quantum dots can be induced by the Berry phase. The nonreciprocity arises in relatively weak magnetic fields and is manifest in anomalously large field-induced splittings of quantum dot resonances which are degenerate at B =0 due to time-reversal symmetry. This exotic behavior, which is governed by field-induced jumps in the Berry phase of confined electronic states, is unique to quantum dots in Dirac materials and is absent in conventional quantum dots. The effect is strong for gapless Dirac particles and can overwhelm the B -induced orbital and Zeeman splittings. A finite Dirac mass suppresses the effect. The nonreciprocity, predicted for generic two-dimensional Dirac materials, is accessible through Faraday and Kerr optical rotation measurements and scanning tunneling spectroscopy.
Unveiling the physics of the Thomson jumping ring
Ladera, Celso L.; Donoso, Guillermo
2015-04-01
We present a new theoretical model and validating experiments that unveil the rich physics behind the flight of the conductive ring in the Thomson experiment—physics that is hard to see because of the rapid motion. The electrodynamics of the flying ring exhibits interesting features, e.g., varying mutual inductance between the ring and the electromagnet. The dependences of the ring electrodynamics upon time and position as the ring travels upward are conveniently separated and determined to obtain a comprehensive view of the ring motion. We introduce a low-cost jumping ring setup that incorporates pickup coils connected in opposition, allowing us to scrutinize the ring electrodynamics and confirm our theoretical model with good accuracy. This work is within the reach of senior students of science or engineering, and it can be implemented either as a teaching laboratory experiment or as an open-ended project.
The naked toy model of a jumping ring
Donoso, Guillermo; Ladera, Celso L.
2014-01-01
We present a comprehensive analytical model of the well-known jumping ring—in fact an improved version of that system--as well as the experimental results that validate the model. Particular attention is paid to the magnetic driving force, whose explicit dependences upon the phase, amplitude and frequency of the exciting current we manage to separate experimentally and plot, so that it becomes evident how the magnetic force on the ring actually arises and evolves in time. We are able to measure not only the large Foucault currents that arise in the ring, but also the magnetic field generated by the ring itself in spite of the presence of the comparable magnetic field in which the ring moves.
Jump electroconductivity in the laser deposited nanoclustered structures
Antipov, A.; Shagurina, A.; Osipov, A.; Istratov, A.; Skryabin, I.; Arakelian, S.
2017-01-01
The quantum states verification in cluster semiconductor/metallic structures by jump/tunneling electroconductivity and possible mechanisms for their implementation are considered in experiment and theory. By our laser ablation technique we have nanostructurized the films for which the ability to control the change in their electrical properties does exist by variation of the topology for the system. The granular conductivity specificity has been under study. The current-voltage characteristics behavior has been measured for a nanocluster bimetallic film (Au+Ag), and the experiments for multilayer bimetal thin films of the different composition have been carried out. Two associated mechanisms for electroconductivity occur in the case, i.e. tunnel transition for electrons and electron activation in the frames of the shell model for a cluster system, in dependence on the nanostructure topology.
STATIC STRETCHING DOES NOT REDUCE VARIABILITY, JUMP AND SPEED PERFORMANCE.
de Oliveira, Fábio Carlos Lucas; Rama, Luís Manuel Pinto Lopes
2016-04-01
Stretching is often part of the warm-up routine prior to athletic participation; however, controversial evidence exists on the effects of stretching on countermovement jump (CMJ) and sprint performance. Additionally, analysis of variability between repeated tasks is useful for monitoring players, to analyze factors that could affect the performance, and to guide clinical decisions for training strategies. The purpose of this study was to examine whether static stretching (SS) prior to CMJ and 20-meter (20-m) sprint would affect performance, and to investigate whether SS affects an athlete's ability to perform these tasks consistently. Twenty-two trained healthy athletes (23.2 ± 5.0 years) attended, randomly, two testing sessions, separated by 48 hours. At session one, all participants underwent 10 minutes of dynamic running warm-up followed by the experimental tasks (three CMJ and three 20-m sprint), whereas five minutes of stretching was added after the warm-up routine at session two. All participants performed the same experimental tasks in both sessions. The stretching protocol consisted of five stretching exercises for each lower limb. The paired-samples t-test revealed no significant differences between the stretching protocol condition and no stretching condition for the 20-m sprint (t(21)=.920; p=.368) and CMJ (t(21)=.709; p=.486). There were no significant differences in trial-by-trial variability on 20-m sprint (t(21)=1.934; p=.067) and CMJ scores (t(21)=.793; p=.437) as result of SS. The SS protocol did not modify jumping and running ability in trained healthy athletes. The SS prior to training or competition may not cause detrimental effects to athletic performance. Level III, Nonrandomized controlled trial.
Early environmental conditions shape personality types in a jumping spider
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Jannis eLiedtke
2015-12-01
Full Text Available Individuals of many species across the animal kingdom are found to be less plastic than expected, even in behavioral traits. The existence of consistent behavioral differences between individuals, termed personality differences, is puzzling, since plastic behavior is considered ideal to enable animals to adaptively respond to changes in environmental conditions. In order to elucidate which mechanisms are important for the evolution of personality differences, it is crucial to understand which aspects of the environment are important for the development of personality differences. Here, we tested whether physical or social aspects of the environment during development influence individual differentiation (mean level of behavior using the jumping spider Marpissa muscosa. Furthermore, we assessed whether those behaviors were repeatable, i.e. whether personalities existed. We applied a split-brood design and raised spider siblings in three different environments: a deprived environment with no enrichment, a socially and a physically enriched environment. We focused on exploratory behavior and repeatedly assessed individual behavior in a novel environment and a novel object test. Results show that the environment during development influenced spiders’ exploratory tendencies: spiders raised in enriched environments tended to be more exploratory. Most investigated behaviors were repeatable (i.e. personalities existed across all individuals tested, whereas only few behaviors were also repeatable across individuals that had experienced the same environmental condition. Taken together, our results indicate that external stimuli can influence the development of one aspect of personality, the inter-individual variation (mean level of behavior, in a jumping spider. We also found family by environment interactions on behavioral traits potentially suggesting genetic variation in developmental plasticity.
2008-03-01
grass plantings, and native and ornamental shrubs and trees. The landscaped areas include the Base entryway, Falcon Parkway, medians within the...ferruginous hawk, mountain plover, Preble’s meadow jumping mouse, lynx, and the swift fox could potentially, and in some cases do, occur in the surrounding...Name Status Occurrence Black-Tailed Prairie Dog Cynomys ludovicianus SC Permanent Resident Preble’s Meadow Jumping Mouse Zapus hudsonius preblei FT
Explaining the level of credit spreads: Option-implied jump risk premia in a firm value model
Cremers, K.J.M.; Driessen, J.; Maenhout, P.
2008-01-01
We study whether option-implied jump risk premia can explain the high observed level of credit spreads. We use a structural jump-diffusion firm value model to assess the level of credit spreads generated by option-implied jump risk premia. Prices and returns of equity index and individual options
SITU, Rong
2005-01-01
Derivation of Ito's formulas, Girsanov's theorems and martingale representation theorem for stochastic DEs with jumpsApplications to population controlReflecting stochastic DE techniqueApplications to the stock market. (Backward stochastic DE approach)Derivation of Black-Scholes formula for market with and without jumpsNon-linear filtering problems with jumps.
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I Gusti Ngurah Agung Cahya Prananta
2015-01-01
Full Text Available The effectiveness of jump-shoot technique step jump shoot and still jump shoot in a game is still questionable, because many different assumptions arise. One opinion stated that step jump shoot was more effective and the other stated that and still jump shoot was more efective. Therefore it is necessary to do research on the analysis of the results of step jump shoot and and still jump shoot to improve the accuracy of shooting in a basketball. The experimental research had been conducted on 20samples of people whowere selected randomly from the men's basketball club of the Faculty of Physical Educationand Health of Teacher Training Institute PGRI Bali. Samples were divided into two groups each consisting of 10 people. Group I was given training step jump shoot four sets of 10 reps and Group II training still jump shoot four sets of 10 reps. The data before and after treatment were tested by SPSS computer program. The data were normally distributed and homogeneous so further tested using pairedt-test to compare the average values?? before and after training between each group, while the independent t-test was used to determine differences in mean values?? between the two groups. Paired t-test resulted the obtained data were significantly increased in both treatment groups p=0,001 in Group I and p=0,000 in Group II (p <0.05. Results of independent t-test found that both groups before training did not differ significantly p=0,926 (p>0.05 and after training both groups equally improve the accuracy of shooting because p=0,133 (p>0.05. It was concluded that botht raining improved the shooting accuracy and there was no difference between the effect of step jumps hoot and still jump shoot toward the shooting accuracy. It was suggested to improve the shooting accuracy in basketball used step jump shoot training and still jump shoot training four sets of 10 reps with a training frequency of 4 times a week for 6 weeks
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Julian Bergmann
Full Text Available Postactivation potentiation (PAP has been defined as the increase in twitch torque after a conditioning contraction. The present study aimed to investigate the effectiveness of hops as conditioning contractions to induce PAP and increase performance in subsequent maximal drop jumps. In addition, we wanted to test if and how PAP can contribute to increases in drop jump rebound height. Twelve participants performed 10 maximal two-legged hops as conditioning contractions. Twitch peak torques of triceps surae muscles were recorded before and after the conditioning hops. Then, subjects performed drop jumps with and without 10 conditioning hops before each drop jump. Recordings included ground reaction forces, ankle and knee angles and electromyographic activity in five leg muscles. In addition, efferent motoneuronal output during ground contact was estimated with V-wave stimulation. The analyses showed that after the conditioning hops, twitch peak torques of triceps surae muscles were 32% higher compared to baseline values (P < 0.01. Drop jumps performed after conditioning hops were significantly higher (12%, P < 0.05, but V-waves and EMG activity remained unchanged. The amount of PAP and the change in drop jump rebound height were positively correlated (r(2 = 0.26, P < 0.05. These results provide evidence for PAP in triceps surae muscles induced by a bout of hops and indicate that PAP can contribute to the observed performance enhancements in subsequent drop jumps. The lack of change in EMG activity and V-wave amplitude suggests that the underlying mechanisms are more likely intramuscular than neural in origin.
Optimisation of phase ratio in the triple jump using computer simulation.
Allen, Sam J; King, Mark A; Yeadon, M R Fred
2016-04-01
The triple jump is an athletic event comprising three phases in which the optimal proportion of each phase to the total distance jumped, termed the phase ratio, is unknown. This study used a whole-body torque-driven computer simulation model of all three phases of the triple jump to investigate optimal technique. The technique of the simulation model was optimised by varying torque generator activation parameters using a Genetic Algorithm in order to maximise total jump distance, resulting in a hop-dominated technique (35.7%:30.8%:33.6%) and a distance of 14.05m. Optimisations were then run with penalties forcing the model to adopt hop and jump phases of 33%, 34%, 35%, 36%, and 37% of the optimised distance, resulting in total distances of: 13.79m, 13.87m, 13.95m, 14.05m, and 14.02m; and 14.01m, 14.02m, 13.97m, 13.84m, and 13.67m respectively. These results indicate that in this subject-specific case there is a plateau in optimum technique encompassing balanced and hop-dominated techniques, but that a jump-dominated technique is associated with a decrease in performance. Hop-dominated techniques are associated with higher forces than jump-dominated techniques; therefore optimal phase ratio may be related to a combination of strength and approach velocity.
Portfolio rebalancing error with jumps and mean reversion in asset prices
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Xingbo Xu
2011-01-01
Full Text Available We analyze the error between a discretely rebalanced portfolio and its continuously rebalanced counterpart in the presence of jumps or mean-reversion in the underlying asset dynamics. With discrete rebalancing, the portfolio’s composition is restored to a set of fixed target weights at discrete intervals; with continuous rebalancing, the target weights are maintained at all times. We examine the difference between the two portfolios as the number of discrete rebalancing dates increases. With either mean reversion or jumps, we derive the limiting variance of the relative error between the two portfolios. With mean reversion and no jumps, we show that the scaled limiting error is asymptotically normal and independent of the level of the continuously rebalanced portfolio. With jumps, we show that the scaled relative error cannot converge to a normal distribution, though asymptotic normality can be recovered if jumps are smaller at higher rebalancing frequencies. For both the mean-reverting and jump-diffusion cases, we derive “volatility adjustments” to improve the approximation of the discretely rebalanced portfolio by the continuously rebalanced portfolio, based on on the limiting covariance between the relative rebalancing error and the level of the continuously rebalanced portfolio. These results are based on strong approximation results for jump-diffusion processes.
Battaglia, Claudia; D'Artibale, Emanuele; Fiorilli, Giovanni; Piazza, Marina; Tsopani, Despina; Giombini, Arrigo; Calcagno, Giuseppe; di Cagno, Alessandra
2014-12-01
The aim of this study was to evaluate whether a mental training protocol could improve gymnastic jumping performance. Seventy-two rhythmic gymnasts were randomly divided into an experimental and control group. At baseline, experimental group completed the Movement Imagery Questionnaire Revised (MIQ-R) to assess the gymnast ability to generate movement imagery. A repeated measures design was used to compare two different types of training aimed at improving jumping performance: (a) video observation and PETTLEP mental training associated with physical practice, for the experimental group, and (b) physical practice alone for the control group. Before and after six weeks of training, their jumping performance was measured using the Hopping Test (HT), Drop Jump (DJ), and Counter Movement Jump (CMJ). Results revealed differences between jumping parameters F(1,71)=11.957; p<.01, and between groups F(1,71)=10.620; p<.01. In the experimental group there were significant correlations between imagery ability and the post-training Flight Time of the HT, r(34)=-.295, p<.05 and the DJ, r(34)=-.297, p<.05. The application of the protocol described herein was shown to improve jumping performance, thereby preserving the elite athlete's energy for other tasks. Copyright © 2014 Elsevier B.V. All rights reserved.
Abidin, Nahdiya Zainal; Adam, Mohd Bakri
2013-01-01
Vertical jump is an index representing leg/kick power. The explosive movement of the kick is the key to scoring in martial arts competitions. It is important to determine factors that influence the vertical jump to help athletes improve their leg power. The objective of the present study is to identify anthropometric factors that influence vertical jump height for male and female martial arts athletes. Twenty-nine male and 25 female athletes participated in this study. Participants were Malaysian undergraduate students whose ages ranged from 18 to 24 years old. Their heights were measured using a stadiometer. The subjects were weighted using digital scale. Body mass index was calculated by kg/m(2). Waist-hip ratio was measured from the ratio of waist to hip circumferences. Body fat % was obtained from the sum of four skinfold thickness using Harpenden callipers. The highest vertical jump from a stationary standing position was recorded. The maximum grip was recorded using a dynamometer. For standing back strength, the maximum pull upwards using a handle bar was recorded. Multiple linear regression was used to obtain the relationship between vertical jump height and explanatory variables with gender effect. Body fat % has a significant negative relationship with vertical jump height (P martial arts athletes can be predicted by body fat %. The vertical jump for male is higher than for their female counterparts. Reducing body fat by proper dietary planning will help to improve leg power.
Chen, Ying-Yi; Liaw, Lih-Jiun; Liang, Jing-Min; Hung, Wei-Tso; Guo, Lan-Yuen; Wu, Wen-Lan
2013-05-01
To evaluate timing perception ability and motor coordination in children with ADHD (Attention Deficit Hyperactivity Disorder) while rope jumping at different rates. Rope jumping at (1) a constant tempo of 100 for 15 s (RJ-C) and (2) two randomly permutated tempos (80, 100, or 120) for 15 s (RJ-V). The "timing variation while jumping", "timing variation while whirling", and "hand-foot deviation time" in each rope jumping cycle were recorded, to assess the time estimation ability. 10 children with ADHD (9.65 ± 1.27 years) and 10 children without ADHD (9.93 ± 1.54 years) were recruited. The ADHD group showed greater variation in time between the foot jumping and the rope whirling tasks. Also, the median value of hand-foot deviation time was greater in the ADHD group (3.34 ms) than in the control group (1.75 ms). In RJ-V, the control group was able to modify their pace and respond to the target speed in the post-phase, while the ADHD group could not. Impaired timing perception leads to less accurate performance during rope jumping for ADHD children. The findings also reveal that poor hand-foot coordination results in poor control of simultaneous movements of the upper and lower limbs during rope jumping. Copyright © 2012 Elsevier Ltd. All rights reserved.
pH-jump induced α-helix folding of poly-L-glutamic acid
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Donten, Mateusz L. [Institute of Physical Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland); Hamm, Peter, E-mail: phamm@pci.uzh.ch [Institute of Physical Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zürich (Switzerland)
2013-08-30
Highlights: ► pH-jump as truly biomimetic tool to initiate non-equilibrium dynamics of biomolecules. ► Design criteria to widen the applicability of pH-jumps are developed. ► Folding of poly-L-Glu in dependence of starting pH, pH jump size and helix length. ► Length dependence provides strong evidence for a nucleation–propagation scenario. - Abstract: pH jumps are a truly biomimetic technique to initiate non-equilibrium dynamics of biomolecules. In this work, the pH jump induced α-helix folding of poly-L-glutamic acid is investigated upon proton release from o-nitrobenzaldehyde. The aim of this work is twofold: On the one hand, design criteria of pH jump experiments are discussed, on the other hand, the folding mechanism of poly-L-glutamic acid is clarified by probing the IR response of the amide I band. Its folding kinetics is studied in dependence of the starting pD, the size of the pD jump and the length of the helix. While no dependence on the first two parameters could be detected, the folding time varies from 0.6 μs to 1.8 μs for helix lengths of 20 residue to 440 residue, respectively. It converges to a long-length limit at about 50 residue, a result which is attributed to a nucleation–propagation mechanism.
Kim, Seyoung; Park, Sukyung; Choi, Sangkyu
2014-09-22
In this study, we developed a curve-fit model of countermovement dynamics and examined whether the characteristics of a countermovement jump can be quantified using the model parameter and its scaling; we expected that the model-based analysis would facilitate an understanding of the basic mechanisms of force reduction and propulsion with a simplified framework of the center of mass (CoM) mechanics. Ten healthy young subjects jumped straight up to five different levels ranging from approximately 10% to 35% of their body heights. The kinematic and kinetic data on the CoM were measured using a force plate system synchronized with motion capture cameras. All subjects generated larger vertical forces compared with their body weights from the countermovement and sufficiently lowered their CoM position to support the work performed by push-off as the vertical elevations became more challenging. The model simulation reasonably reproduced the trajectories of vertical force during the countermovement, and the model parameters were replaced by linear and polynomial regression functions in terms of the vertical jump height. Gradual scaling trends of the individual model parameters were observed as a function of the vertical jump height with different degrees of scaling, depending on the subject. The results imply that the subjects may be aware of the jumping dynamics when subjected to various vertical jump heights and may select their countermovement strategies to effectively accommodate biomechanical constraints, i.e., limited force generation for the standing vertical jump. Copyright © 2014 Elsevier Ltd. All rights reserved.
Bionic Mechanism and Kinematics Analysis of Hopping Robot Inspired by Locust Jumping
Institute of Scientific and Technical Information of China (English)
Diansheng Chen; Junmao Yin; Kai Zhao; Wanjun Zheng; Tianmiao Wang
2011-01-01
A flexible-rigid hopping mechanism which is inspired by the locust jumping was proposed,and its kinematic characteristics were analyzed.A series of experiments were conducted to observe locust morphology and jumping process.According to classic mechanics,the jumping process analysis was conducted to build the relationship of the locust jumping parameters.The take-off phase was divided into four stages in detail.Based on the biological observation and kinematics analysis,a mechanical model was proposed to simulate locust jumping.The forces of the flexible-rigid hopping mechanism at each stage were analyzed.The kinematic analysis using pseudo-rigid-body model was described by D-H method.It is confirmed that the proposed bionic mechanism has the similar performance as the locust hind leg in hopping.Moreover,the jumping angle which decides the jumping process was discussed,and its relation with other parameters was established.A calculation case analysis corroborated the method.The results of this paper show that the proposed bionic mechanism which is inspired by the locust hind limb has an excellent kinematics performance,which can provide a foundation for design and motion planning of the hopping robot.
Segmental and kinetic contributions in vertical jumps performed with and without an arm swing.
Feltner, Michael E; Bishop, Elijah J; Perez, Cassandra M
2004-09-01
To determine the contributions of the motions of the body segments to the vertical ground reaction force (Fz), the joint torques produced by the leg muscles, and the time course of vertical velocity generation during a vertical jump, 15 men were videotaped performing countermovement vertical jumps from a force plate with and without an arm swing. Linear kinematic, Fz, and joint torque data were computed and compared using repeated measures analysis of variance. Maximum jump height was significantly larger in the arm swing jumps compared to the no arm swing jumps and was due to both a higher height of the center of mass (CM) at takeoff (54%) and a larger vertical velocity of the CM at takeoff (46%). The net vertical impulse created during the propulsive phase of the arm swing jumps was greater due to a trend of an increased duration (0.021 s) of the propulsive phase and not to larger average values of Fz. In the arm swing jumps, the arm motion resulted in the arms making a larger maximal contribution to Fz during the middle of the propulsive phase and decreased the negative contribution of the trunk-head and thigh to Fz late in the propulsive phase. Last, the arm swing decreased the extensor torques at the hip (13%), knee (10%), and ankle (10%) early in the propulsive phase but augmented these same extensor torques later in the propulsive phase.
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Giuseppe Marcolin
2017-06-01
Full Text Available Kinesiologic elastic tape is widely used for both clinical and sport applications although its efficacy in enhancing agonistic performance is still controversial. Aim of the study was to verify in a group of healthy basketball players whether a neuromuscular taping application (NMT on ankle and knee joints could affect the kinematic and the kinetic parameters of the jump, either by enhancing or inhibiting the functional performance. Fourteen healthy male basketball players without any ongoing pathologies at upper limbs, lower limbs and trunk volunteered in the study. They randomly performed 2 sets of 5 counter movement jumps (CMJ with and without application of Kinesiologic tape. The best 3 jumps of each set were considered for the analysis. The Kinematics parameters analyzed were: knees maximal flexion and ankles maximal dorsiflexion during the push off phase, jump height and take off velocity. Vertical ground reaction force and maximal power expressed in the push off phase of the jump were also investigated. The NMT application in both knees and ankles showed no statistically significant differences in the kinematic and kinetic parameters and did not interfere with the CMJ performance. Bilateral NMT application in the group of healthy male basketball players did not change kinematics and kinetics jump parameters, thus suggesting that its routine use should have no negative effect on functional performance. Similarly, the combined application of the tape on both knees and ankles did not affect in either way jump performance.
Hennig, J; Laschefski, U; Opper, C
1994-01-01
A study on 12 novice bungee jumpers was performed to investigate the influence of acute psychological stress on levels of cortisol in saliva, beta-endorphin immunoreactivity as well as the number of leukocytes in peripheral blood. In addition, heart rate and blood pressure as well as ratings on emotional states were recorded. Furthermore, correlations between ratings on mood and biochemical stress markers were computed. As expected, subjective ratings on anxiety were increased prior to the jump and were markedly reduced after the jump. Salivary cortisol was also increased after the jump and decreased to baseline within the next hour. In contrast, ratings on euphoria increased markedly after performing the jump and remained highly elevated for the next 30 min. An increase of more than 200% in beta-endorphin immunoreactivity after the jump was observed. In contrast to levels of cortisol, the concentration of beta-endorphin recorded immediately after the jump was significantly correlated with ratings on euphoria obtained at subsequent measurements indicating a relationship between beta-endorphins and euphoria. Additional increase of the number of blood leukocytes and of heart rate and blood pressure indicate that various systems of the organism are markedly affected by the exceptional eustress of bungee jumping.
Effects of Agent-Environment Symmetry on the Coordination Dynamics of Triadic Jumping
Kijima, Akifumi; Shima, Hiroyuki; Okumura, Motoki; Yamamoto, Yuji; Richardson, Michael J.
2017-01-01
We investigated whether the patterns of coordination that emerged during a three-participant (triadic) jumping task were defined by the symmetries of the (multi) agent-environment task space. Triads were instructed to jump around different geometrical arrangements of hoops. The symmetry of the hoop geometry was manipulated to create two symmetrical and two asymmetrical participant-hoop configurations. Video and motion tracking recordings were employed to determine the frequencies of coordination misses (collisions or failed jumps) and during 20 successful jump sequences, the jump direction chosen (clockwise vs. counterclockwise) and the patterning of between participant temporal movement lags within and across jump events. The results revealed that the (a)symmetry of the joint action workspace significantly influenced the (a)symmetry of the jump direction dynamics and, more importantly, the (a)symmetry of the between participant coordination lags. The symmetrical participant-hoop configurations resulted in smaller overall movement lags and a more spontaneous, interchangeable leader/follower relationship between participants, whereas the asymmetrical participant-hoop configurations resulted in slightly larger overall movements lags and a more explicit, persistent asymmetry in the leader/follower relationship of participants. The degree to which the patterns of behavioral coordination that emerged were consistent with the theory of symmetry groups and spontaneous and explicit symmetry-breaking are discussed. PMID:28210231
ANKLE TAPING DOES NOT IMPAIR PERFORMANCE IN JUMP OR BALANCE TESTS
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Javier Abián-Vicén
2008-09-01
Full Text Available This study aimed to investigate the influence of prophylactic ankle taping on two balance tests (static and dynamic balance and one jump test, in the push off and the landing phase. Fifteen active young subjects (age: 21.0 ± 4.4 years without previous ankle injuries volunteered for the study. Each participant performed three tests in two different situations: with taping and without taping. The tests were a counter movement jump, static balance, and a dynamic posturography test. The tests and conditions were randomly performed. The path of the center of pressures was measured in the balance tests, and the vertical ground reaction forces were recorded during the push-off and landing phases of the counter movement jump. Ankle taping had no influence on balance performance or in the push off phase of the jump. However, the second peak vertical force value during the landing phase of the jump was 12% greater with ankle taping (0.66 BW, 95% CI -0.64 to 1.96. The use of prophylactic ankle taping had no influence on the balance or jump performance of healthy young subjects. In contrast, the taped ankle increased the second peak vertical force value, which could be related to a greater risk of injury produced by the accumulation of repeated impacts in sports where jumps are frequently performed
Kinesiology tape does not promote vertical jumping performance: A deceptive crossover trial.
Cheung, R T H; Yau, Q K C; Wong, K; Lau, P; So, A; Chan, N; Kwok, C; Poon, K Y; Yung, P S H
2016-02-01
Kinesiology tape (KINTAPE) is one of the most common adhesive therapeutic tapes. Apart from clinical applications, KINTAPE claims to be able to enhance functional performance by muscle activity facilitation. However, emerging evidence suggests that the isokinetic muscle strength remains similar when the placebo effect is eliminated. In view of the weak relationship between functional performance and isokinetic muscle strength, this study investigated the true effects of KINTAPE on functional performance. Deceptive, randomized, and crossover trial. Sixty four experienced volleyball players performed vertical jumping test under three taping conditions: true facilitative KINTAPE, sham KINTAPE, and no KINTAPE. Under the pretense of applying adhesive muscle sensors, KINTAPE was applied to their quadriceps and gastrocnemius in the first two conditions. Mean maximum jump height and peak jump power were averaged from three attempts. Within-subject comparisons were conducted by repeated measure ANOVA. Out of 64 participants, 30 of them were successfully deceived and they were ignorant about KINTAPE. No significant differences were found in both maximum jump height (η(2) = 0.001; p = 0.241) and peak jump power (η(2) = 0.001; p = 0.134) between three taping conditions. The results showed that KINTAPE did not facilitate muscle performance by generating higher jumping power or yielding a better jumping performance. These findings reinforce that previously reported muscle facilitatory effects or functional enhancement using KINTAPE may be attributed to placebo effects. Copyright © 2015 Elsevier Ltd. All rights reserved.
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Shaw Stephen R
2008-09-01
Full Text Available Abstract Background Many insects jump by storing and releasing energy in elastic structures within their bodies. This allows them to release large amounts of energy in a very short time to jump at very high speeds. The fastest of the insect jumpers, the froghopper, uses a catapult-like elastic mechanism to achieve their jumping prowess in which energy, generated by the slow contraction of muscles, is released suddenly to power rapid and synchronous movements of the hind legs. How is this energy stored? Results The hind coxae of the froghopper are linked to the hinges of the ipsilateral hind wings by pleural arches, complex bow-shaped internal skeletal structures. They are built of chitinous cuticle and the rubber-like protein, resilin, which fluoresces bright blue when illuminated with ultra-violet light. The ventral and posterior end of this fluorescent region forms the thoracic part of the pivot with a hind coxa. No other structures in the thorax or hind legs show this blue fluorescence and it is not found in larvae which do not jump. Stimulating one trochanteral depressor muscle in a pattern that simulates its normal action, results in a distortion and forward movement of the posterior part of a pleural arch by 40 μm, but in natural jumping, the movement is at least 100 μm. Conclusion Calculations showed that the resilin itself could only store 1% to 2% of the energy required for jumping. The stiffer cuticular parts of the pleural arches could, however, easily meet all the energy storage needs. The composite structure therefore, combines the stiffness of the chitinous cuticle with the elasticity of resilin. Muscle contractions bend the chitinous cuticle with little deformation and therefore, store the energy needed for jumping, while the resilin rapidly returns its stored energy and thus restores the body to its original shape after a jump and allows repeated jumping.
Hébert-Losier, Kim; Beaven, C Martyn
2014-07-01
Jump tests are often used to assess the effect of interventions because their outcomes are reported valid indicators of functional performance. In this study, we examined the reproducibility of performance parameters from 3 common jump tests obtained using the commercially available Kistler Measurement, Analysis and Reporting Software (MARS). On 2 separate days, 32 men performed 3 squat jumps (SJs), 3 countermovement jumps (CMJs), and 3 standing long jumps (LJs) on a Kistler force-plate. On both days, the performance measures from the best jump of each series were extracted using the MARS. Changes in the mean scores, intraclass correlation coefficients (ICCs), and coefficients of variations (CVs) were computed to quantify the between-day reproducibility of each parameter. Moreover, the reproducibility quantifiers specific to the 3 separate jumps were compared using nonparametric tests. Overall, an acceptable between-day reproducibility (mean ± SD, ICC, and CV) of SJ (0.88 ± 0.06 and 7.1 ± 3.8%), CMJ (0.84 ± 0.17 and 5.9 ± 4.1%), and LJ (0.80 ± 0.13 and 8.1 ± 4.1%) measures was found using the MARS, except for parameters directly relating to the rate of force development (i.e., time to maximal force) and change in momentum during countermovement (i.e., negative force impulse) where reproducibility was lower. A greater proportion of the performance measures from the standing LJs had low ICCs and/or high CVs values most likely owing to the complex nature of the LJ test. Practitioners and researchers can use most of the jump test parameters from the MARS with confidence to quantify changes in the functional ability of individuals over time, except for those relating to the rate of force development or change in momentum during countermovement phases of jumps.
DEFF Research Database (Denmark)
Veraart, Almut
and present a new estimator for the asymptotic ‘variance’ of the centered realised variance in the presence of jumps. Next, we compare the finite sample performance of the various estimators by means of detailed Monte Carlo studies where we study the impact of the jump activity, the jump size of the jumps...... in the price and the presence of additional independent or dependent jumps in the volatility on the finite sample performance of the various estimators. We find that the finite sample performance of realised variance, and in particular of the log–transformed realised variance, is generally good, whereas...
Bergmann, Julian; Kramer, Andreas; Gruber, Markus
2013-01-01
Postactivation potentiation (PAP) has been defined as the increase in twitch torque after a conditioning contraction. The present study aimed to investigate the effectiveness of hops as conditioning contractions to induce PAP and increase performance in subsequent maximal drop jumps. In addition, we wanted to test if and how PAP can contribute to increases in drop jump rebound height. Twelve participants performed 10 maximal two-legged hops as conditioning contractions. Twitch peak torques of triceps surae muscles were recorded before and after the conditioning hops. Then, subjects performed drop jumps with and without 10 conditioning hops before each drop jump. Recordings included ground reaction forces, ankle and knee angles and electromyographic activity in five leg muscles. In addition, efferent motoneuronal output during ground contact was estimated with V-wave stimulation. The analyses showed that after the conditioning hops, twitch peak torques of triceps surae muscles were 32% higher compared to baseline values (P triceps surae muscles induced by a bout of hops and indicate that PAP can contribute to the observed performance enhancements in subsequent drop jumps. The lack of change in EMG activity and V-wave amplitude suggests that the underlying mechanisms are more likely intramuscular than neural in origin.
Seo, KyoChul
2017-01-01
[Purpose] The purpose of this study was to examine the effect of a dance music jump rope exercise on changes Pulmonary Function and body mass index in female overweight subjects in their 20’s. [Subjects and Methods] The subjects were randomly assigned to the dance music jump rope exercise group and the stationary cycle exercise group. All subjects have conducted the exercises three times a week for four weeks. Pulmonary function was evaluated using a spirometer, and body mass index was evaluated using an InBody 3.0. [Results] The findings of this study showed significant improvements in the voluntary capacity and body mass index of the experimental groups. Vital capacity was higher in the music jump rope exercise group than the stationary cycle exercise group, and body mass index was lower in the music jump rope exercise group than the stationary cycle exercise group. [Conclusion] This study showed that the dance music jump rope exercise can be used to improve vital capacity and body mass index. PMID:28878460
Seo, KyoChul
2017-08-01
[Purpose] The purpose of this study was to examine the effect of a dance music jump rope exercise on changes Pulmonary Function and body mass index in female overweight subjects in their 20's. [Subjects and Methods] The subjects were randomly assigned to the dance music jump rope exercise group and the stationary cycle exercise group. All subjects have conducted the exercises three times a week for four weeks. Pulmonary function was evaluated using a spirometer, and body mass index was evaluated using an InBody 3.0. [Results] The findings of this study showed significant improvements in the voluntary capacity and body mass index of the experimental groups. Vital capacity was higher in the music jump rope exercise group than the stationary cycle exercise group, and body mass index was lower in the music jump rope exercise group than the stationary cycle exercise group. [Conclusion] This study showed that the dance music jump rope exercise can be used to improve vital capacity and body mass index.
DEFF Research Database (Denmark)
Santos, Luis; Fernández-Río, Javier; Fernández-García, Benjamín
2016-01-01
The main goal of the study was to assess the effects of slackline training on the postural control system and jump performance of athletes. Twenty-five female basketball players were randomized into 2 groups: control (N 12) and experimental (N 13). The latter experienced a 6-week supervised...... training in both groups. Performance on a countermovement jump test significantly improved only in the experimental group (effect side was 3.21 and 1.36 [flight time and jump height, respectively], which is described as a large effect). Mechanical power of the legs, as measured through the 30-second...
Influence of Plyometrics on Jump Capabilities in Technical and Aesthetical Sports
Directory of Open Access Journals (Sweden)
Mlsnová Gabriela
2017-05-01
Full Text Available The aim of the study was to examine the effect of plyometric exercises on explosive strength of lower extremities in girls performing of technical and aesthetical sports. Experiment was carried out on three groups; artistic gymnasts (VG, n = 15; age = 12.4 ± 0.7 years, fitness girls (VF, n = 15; age = 13.8 ± 1.9 years and dancers (VD, n = 15; age = 13.8 ± 2 years. To check, the control group of general population was involved in the study (VK, n = 15; age = 13.9 ± 1.5 years. Following tests on jump ergometer Fitro Jumper were carried out at the beginning and at the end of experimental period: countermovement jump without and with arms swing and 10- second series of repeated vertical jumps. Plyometric program consisted of two plyometric units a week during thirty weeks. The results show that higher improvement in all evaluated tests achieved the group of fitness. In the countermovement jump without arm swing was observed improvement height of the jump 3.4 ± 1.4 cm (p ˂ 0.00001, in the countermovement jump with arm swing 5.7 ± 1.5 cm (p ˂ 0.00001, in difference of height of the jump between countermovement jump with and without arms swing 2.3 ± 1 cm (p ˂ 0.00001, in ten second series of repeated vertical jumps without arms swing in the height of jump 4.2 ± 1.6 cm (p ˂ 0.00001 and in power in active take off phase 8.8 ± 2.2 W.kg-1 (p ˂ 0.00001. Based on finding the study and in coherence with data from literature, we can conclude the effect of plyometric exercises was effective in combination with specific-strength training. Jumping ability is limiting factor of sport performance in technical and aesthetical sports and implementation of plyometric exercises to the training is highly recommend. The high level of jump capabilities can improve the quality and technique of performance complex acrobatic elements and dance leaps thereby increasing overall evaluation of performance in selected sports.
Full-State Linearization and Stabilization of SISO Markovian Jump Nonlinear Systems
Directory of Open Access Journals (Sweden)
Zhongwei Lin
2013-01-01
Full Text Available This paper investigates the linearization and stabilizing control design problems for a class of SISO Markovian jump nonlinear systems. According to the proposed relative degree set definition, the system can be transformed into the canonical form through the appropriate coordinate changes followed with the Markovian switchings; that is, the system can be full-state linearized in every jump mode with respect to the relative degree set n,…,n. Then, a stabilizing control is designed through applying the backstepping technique, which guarantees the asymptotic stability of Markovian jump nonlinear systems. A numerical example is presented to illustrate the effectiveness of our results.
A Directed Continuous Time Random Walk Model with Jump Length Depending on Waiting Time
Directory of Open Access Journals (Sweden)
Long Shi
2014-01-01
Full Text Available In continuum one-dimensional space, a coupled directed continuous time random walk model is proposed, where the random walker jumps toward one direction and the waiting time between jumps affects the subsequent jump. In the proposed model, the Laplace-Laplace transform of the probability density function P(x,t of finding the walker at position x at time t is completely determined by the Laplace transform of the probability density function φ(t of the waiting time. In terms of the probability density function of the waiting time in the Laplace domain, the limit distribution of the random process and the corresponding evolving equations are derived.
Modeling and forecasting electricity price jumps in the Nord Pool power market
DEFF Research Database (Denmark)
Knapik, Oskar
extreme prices and forecasting of the price jumps is crucial for risk management and market design. In this paper, we consider the problem of the impact of fundamental price drivers on forecasting of price jumps in NordPool intraday market. We develop categorical time series models which take into account...... i) price drivers, ii) persistence, iii) seasonality of electricity prices. The models are shown to outperform commonly-used benchmark. The paper shows how crucial for price jumps forecasting is to incorporate additional knowledge on price drivers like loads, temperature and water reservoir level...
European Option Pricing with Transaction Costs in Lévy Jump Environment
Directory of Open Access Journals (Sweden)
Jiayin Li
2014-01-01
Full Text Available The European option pricing problem with transaction costs is investigated for a risky asset price model with Lévy jump. By the aid of arbitrage pricing theory and the generalized Itô formula (which includes Poisson jump, the explicit solution to the risk asset price model is given. According to arbitrage-free principle, we first discretize the continuous-time model. Then, in each small time interval, the transaction costs are introduced. By using the Δ-hedging strategy, the explicit solutions of the European options pricing formula with transaction costs are given for the risky asset price model with Lévy jump.
Asymptotic behavior of stochastic Gilpin-Ayala mutualism model with jumps
Directory of Open Access Journals (Sweden)
Xinhong Zhang
2013-07-01
Full Text Available This article concerns the study of stochastic Gilpin-Ayala mutualism models with white noise and Poisson jumps. Firstly, an explicit solution for one-dimensional Gilpin-Ayala mutualism model with jumps is obtained and the asymptotic pathwise behavior is analyzed. Then, sufficient conditions for the existence of global positive solutions, stochastically ultimate boundedness and stochastic permanence are established for the n-dimensional model. Asymptotic pathwise behavior of n-dimensional Gilpin-Ayala mutualism model with jumps is also discussed. Finally numerical examples are introduced to illustrate the results developed.
What moves the European carbon market? Insights from conditional jump models
Energy Technology Data Exchange (ETDEWEB)
Gronwald, Marc; Ketterer, Janina [Munich Univ. (Germany). Ifo Institute - Leibniz Institute for Economic Research
2012-04-15
This paper is concerned with carbon price volatility and the underlying causes of large price movements in the European emissions trading market. Based on the application of a combined jump-GARCH model the behavior of EUA prices is characterized. The jump- GARCH model explains the unsteady carbon price movement well and, moreover, shows that between 40 and 60 percent of the carbon price variance are triggered by jumps. Information regarding EUA supply and news from international carbon markets are identified as important drivers of these price spikes. These results can lead regulators the way if smoother carbon prices are desired.
Changes in long jump take-off technique with increasing run-up speed
Bridgett, LA; Linthorne, NP
2006-01-01
The aim of this study was to determine the influence of run-up speed on take-off technique in the long jump. Seventy-one jumps by an elite male long jumper were recorded in the sagittal plane by a high-speed video camera. A wide range of run-up speeds was obtained using direct intervention to set the length of the athlete's run-up. As the athlete's run-up speed increased, the jump distance and take-off speed increased, the leg angle at touchdown remained almost unchanged, and the take-off ang...
Power and bipower variation with stochastic volatility and jumps (with discussion)
DEFF Research Database (Denmark)
Barndorff-Nielsen, Ole Eiler; Shephard, N.
2004-01-01
This article shows that realized power variation and its extension, realized bipower variation, which we introduce here, are somewhat robust to rare jumps. We demonstrate that in special cases, realized bipower variation estimates integrated variance in stochastic volatility models, thus providing...... a model-free and consistent alternative to realized variance. Its robustness property means that if we have a stochastic volatility plus infrequent jumps process, then the difference between realized variance and realized bipower variation estimates the quadratic variation of the jump component...
Robust mean field games for coupled Markov jump linear systems
Moon, Jun; Başar, Tamer
2016-07-01
We consider robust stochastic large population games for coupled Markov jump linear systems (MJLSs). The N agents' individual MJLSs are governed by different infinitesimal generators, and are affected not only by the control input but also by an individual disturbance (or adversarial) input. The mean field term, representing the average behaviour of N agents, is included in the individual worst-case cost function to capture coupling effects among agents. To circumvent the computational complexity and analyse the worst-case effect of the disturbance, we use robust mean field game theory to design low-complexity robust decentralised controllers and to characterise the associated worst-case disturbance. We show that with the individual robust decentralised controller and the corresponding worst-case disturbance, which constitute a saddle-point solution to a generic stochastic differential game for MJLSs, the actual mean field behaviour can be approximated by a deterministic function which is a fixed-point solution to the constructed mean field system. We further show that the closed-loop system is uniformly stable independent of N, and an approximate optimality can be obtained in the sense of ε-Nash equilibrium, where ε can be taken to be arbitrarily close to zero as N becomes sufficiently large. A numerical example is included to illustrate the results.
Characteristic functions based on a quantum jump trajectory
Liu, Fei; Xi, Jingyi
2016-12-01
Characteristic functions (CFs) provide a very efficient method for evaluating the probability density functions of stochastic thermodynamic quantities and investigating their statistical features in quantum master equations (QMEs). A conventional procedure for obtaining these functions is to resort to a first-principles approach; namely, the evolution equations of the CFs of the combined system and its environment are obtained and then projected into the degrees of freedom of the system. However, the QMEs can be unraveled by a quantum jump trajectory. Thermodynamic quantities such as the heat, work, and entropy production can be well defined along a trajectory. Hence, on the basis of the notion of a trajectory, can we straightforwardly derive these CFs, e.g., their evolution equations? This is essential to establish the self-contained stochastic thermodynamics of a QME. In this paper, we show that it is indeed plausible and also simple. Particularly, these equations are fully consistent with those obtained by the first-principles method. Our results have practical significance; they indicate that the quantum fluctuation relations could be verified by more realistic photocounting experiments.
Autonomous stair-climbing with miniature jumping robots.
Stoeter, Sascha A; Papanikolopoulos, Nikolaos
2005-04-01
The problem of vision-guided control of miniature mobile robots is investigated. Untethered mobile robots with small physical dimensions of around 10 cm or less do not permit powerful onboard computers because of size and power constraints. These challenges have, in the past, reduced the functionality of such devices to that of a complex remote control vehicle with fancy sensors. With the help of a computationally more powerful entity such as a larger companion robot, the control loop can be closed. Using the miniature robot's video transmission or that of an observer to localize it in the world, control commands can be computed and relayed to the inept robot. The result is a system that exhibits autonomous capabilities. The framework presented here solves the problem of climbing stairs with the miniature Scout robot. The robot's unique locomotion mode, the jump, is employed to hop one step at a time. Methods for externally tracking the Scout are developed. A large number of real-world experiments are conducted and the results discussed.
Different training schedules influence platelet aggregation in show jumping horses.
Giannetto, C; Arfuso, F; Fazio, F; Giudice, E; Pietro, S Di; Bruschetta, D; Piccione, G
2017-03-28
Depending on the intensity, duration and type of physical exercise, equine metabolism has to adapt to nervous, cardiovascular, endocrine and respiratory system requirements. In horses, exercise and training are known to have considerable effects on the mechanisms of hemostatic system involving platelet activity. The aim of the present study was to evaluate the effect of different training schedules on platelet aggregation in 15 Italian Saddle jumping horses. Animals were divided into three equal groups: Group A was subjected to a high intensity-training program; group B to a light training program, group C included sedentary horses. From each animal, blood samples were collected by jugular venipuncture at rest on the 1st, 3rd and 5th days, and afterwards, once a week, for a total of 5 weeks data recording, in order to assess the maximum degree of platelet aggregation and the initial velocity of aggregation (slope) platelet aggregation. Two-way analysis of variance (ANOVA) showed a significant effect of the different training schedules on studied parameters. The results revealed a different degree of platelet aggregation and a different initial velocity of platelet aggregation that changes during the different training schedules in horses that could represent a different protective endothelial mechanism. These findings could have an important role for a clearer knowledge of the physiological reference values of platelet aggregation and for a better interpretation of these variations during the training.
An alternative strategy to teach biomechanics: The long jump
Energy Technology Data Exchange (ETDEWEB)
Vega, G J de la [School of Exactly, Physical and Naturals Science. I de la Roza 590 (Oeste). CP 5413. San Juan (Argentina); Aguilera, J A [School of Exactly, Physical and Naturals Science. I de la Roza 590 (Oeste). CP 5413. San Juan (Argentina); Puzzella, A E [School of Exactly, Physical and Naturals Science. I de la Roza 590 (Oeste). CP 5413. San Juan (Argentina); Mallamaci, C C [School of Exactly, Physical and Naturals Science. I de la Roza 590 (Oeste). CP 5413. San Juan (Argentina)
2007-11-15
The work develops an alternative methodology to teach the Physics principles of Parabolic Cannon Shot in the career of Bioengineering using instead the physic-biological relationship of the long jump performed in Athletics. This is a closer-to-reality example for this discipline, and it is a field- and computer laboratory-reproducible practice that is simple to do by using affordable technology, because the practice can be filmed by the students in a real setting for future analysis off classroom hours. The data extracted from the film can be analysed and used to learn the physics of motion of the participating athletes, and to draw conclusions from their hands-on experience. As a main factor of the proposal, this latter characteristic aims at motivating the students to work and participate within a collaborative framework, so as to motivate them to reason and respond the questionnaire issues that stems from a real experience. A significant improvement of knowledge transference is thus attained by promoting teaching (and self-teaching) through reality-based perception, analysis and learning). This work is undergoing its first stage, and its conclusions arise from the observations on team-work dynamics. Quantitative results are expected for the following stages which are under way of execution.
Appraisal of jump distributions in ensemble-based sampling algorithms
Dejanic, Sanda; Scheidegger, Andreas; Rieckermann, Jörg; Albert, Carlo
2017-04-01
Sampling Bayesian posteriors of model parameters is often required for making model-based probabilistic predictions. For complex environmental models, standard Monte Carlo Markov Chain (MCMC) methods are often infeasible because they require too many sequential model runs. Therefore, we focused on ensemble methods that use many Markov chains in parallel, since they can be run on modern cluster architectures. Little is known about how to choose the best performing sampler, for a given application. A poor choice can lead to an inappropriate representation of posterior knowledge. We assessed two different jump moves, the stretch and the differential evolution move, underlying, respectively, the software packages EMCEE and DREAM, which are popular in different scientific communities. For the assessment, we used analytical posteriors with features as they often occur in real posteriors, namely high dimensionality, strong non-linear correlations or multimodality. For posteriors with non-linear features, standard convergence diagnostics based on sample means can be insufficient. Therefore, we resorted to an entropy-based convergence measure. We assessed the samplers by means of their convergence speed, robustness and effective sample sizes. For posteriors with strongly non-linear features, we found that the stretch move outperforms the differential evolution move, w.r.t. all three aspects.
Unveiling the physics of the Thomson jumping ring
Ladera, Celso L
2014-01-01
We present a new model, and the validating experiments, that unveil the rich physics behind the flight of a conductive ring in the Thomson experiment, a physics veiled by the fast thrust that impels the ring. We uncover interesting features of the electro-dynamics of the flying ring, e.g. the varying mutual inductance between ring and the thrusting electromagnet, or how to measure the ring proper magnetic field in the presence of the larger field of the electromagnet. We succeed in separating the position and time dependences of the ring variables as it travels upward in a diverging magnetic field, obtaining a comprehensive view of the ring motion. We introduce a low-cost jumping ring set-up that incorporates simple innovative devices, e.g. a couple of pick-up coils connected in opposition that allows us to scrutinize the ring electro-dynamics, and to confirm the predictions of our theoretical model with good accuracy. This work is within the reach of senior students of science or engineering, and it can be e...
Place avoidance learning and memory in a jumping spider.
Peckmezian, Tina; Taylor, Phillip W
2017-03-01
Using a conditioned passive place avoidance paradigm, we investigated the relative importance of three experimental parameters on learning and memory in a salticid, Servaea incana. Spiders encountered an aversive electric shock stimulus paired with one side of a two-sided arena. Our three parameters were the ecological relevance of the visual stimulus, the time interval between trials and the time interval before test. We paired electric shock with either a black or white visual stimulus, as prior studies in our laboratory have demonstrated that S. incana prefer dark 'safe' regions to light ones. We additionally evaluated the influence of two temporal features (time interval between trials and time interval before test) on learning and memory. Spiders exposed to the shock stimulus learned to associate shock with the visual background cue, but the extent to which they did so was dependent on which visual stimulus was present and the time interval between trials. Spiders trained with a long interval between trials (24 h) maintained performance throughout training, whereas spiders trained with a short interval (10 min) maintained performance only when the safe side was black. When the safe side was white, performance worsened steadily over time. There was no difference between spiders tested after a short (10 min) or long (24 h) interval before test. These results suggest that the ecological relevance of the stimuli used and the duration of the interval between trials can influence learning and memory in jumping spiders.
Jumping into buckets, or How to decontaminate overlapping fat jets
Hamaguchi, Koichi; Stoll, Martin
2015-01-01
At the LHC, tagging boosted heavy particle resonances which decay hadronically, such as top quarks and Higgs bosons, can play an essential role in new physics searches. In events with high multiplicity, however, the standard approach to tag boosted resonances by a large-radius fat jet becomes difficult because the resonances are not well-separated from other hard radiation. In this paper, we propose a different approach to tag and reconstruct boosted resonances by using the recently proposed mass-jump jet algorithm. A key feature of the algorithm is the flexible radius of the jets, which results from a terminating veto that prevents the recombination of two hard prongs if their combined jet mass is substantially larger than the masses of the separate prongs. The idea of collecting jets in "buckets" is also used. As an example, we consider the fully hadronic final state of pair-produced vectorlike top partners at the LHC, $pp\\to T\\bar{T}\\to t\\bar{t}HH$, and show that the new approach works better than the corr...
An alternative strategy to teach biomechanics: The long jump
de la Vega, G. J.; Aguilera, J. A.; Puzzella, A. E.; Mallamaci, C. C.
2007-11-01
The work develops an alternative methodology to teach the Physics principles of Parabolic Cannon Shot in the career of Bioengineering using instead the physic-biological relationship of the long jump performed in Athletics. This is a closer-to-reality example for this discipline, and it is a field- and computer laboratory-reproducible practice that is simple to do by using affordable technology, because the practice can be filmed by the students in a real setting for future analysis off classroom hours. The data extracted from the film can be analysed and used to learn the physics of motion of the participating athletes, and to draw conclusions from their hands-on experience. As a main factor of the proposal, this latter characteristic aims at motivating the students to work and participate within a collaborative framework, so as to motivate them to reason and respond the questionnaire issues that stems from a real experience. A significant improvement of knowledge transference is thus attained by promoting teaching (and self-teaching) through reality-based perception, analysis and learning). This work is undergoing its first stage, and its conclusions arise from the observations on team-work dynamics. Quantitative results are expected for the following stages which are under way of execution.
Assessing Reactive Strength Measures in Jumping and Hopping Using the Optojump™ System
National Research Council Canada - National Science Library
Robin Healy; Ian C. Kenny; Andrew J. Harrison
2016-01-01
...) versus a force platform in the estimation of temporal and reactive strength measures. In two separate investigations, twenty physically active males performed double-leg and single-leg drop jumps from a box height...
Directory of Open Access Journals (Sweden)
Bołdak Agnieszka
2014-01-01
Full Text Available Study aim: To determine the role of gender and experience level as factors differentiating state anxiety before and after a parachute jump, and to ascertain relationships between state anxiety and temperament features.
Bołdak Agnieszka; Guszkowska Monika
2014-01-01
Study aim: To determine the role of gender and experience level as factors differentiating state anxiety before and after a parachute jump, and to ascertain relationships between state anxiety and temperament features.
Clemente-Suárez, Vicente Javier; de la Vega, Ricardo; Robles-Pérez, José Juan; Lautenschlaeger, Mario; Fernández-Lucas, Jesús
2016-12-01
We aimed to analyse the effect of experience level in the psychophysiological response and specific fine motor skills of novel and expert parachute warfighters during a tactical combat parachute jump. We analysed blood oxygen saturation, heart rate, salivary cortisol, blood glucose, lactate and creatinkinase, leg strength, isometric hand-grip strength, cortical arousal, specific fine motor skills and cognitive anxiety, somatic anxiety and self-confident before and after a tactical combat parachute jump in 40 warfighters divided in two group, novel (n=17) and expert group (n=23). Novels presented a higher heart rate, lactate, cognitive anxiety, somatic anxiety and a lower self-confident than experts during the jump. We concluded that experience level has a direct effect on the psychophysiological response since novel paratroopers presented a higher psychophysiological response than compared to the expert ones, however this result neither affected the specific fine motor skills nor the muscle structure after a tactical combat parachute jump.
Institute of Scientific and Technical Information of China (English)
TAN Wen-hua
2015-01-01
This paper compares Mark Twain’s The Notorious Jumping Frog of Calaveras County and The Man That Corrupted Had⁃leyburg, in terms of their stylistic and semantic inconsistency, specifically, their narrative technique and moral vision.
Force, Frequency of Head Hits Jump as Young Football Players Get Older
... Force, Frequency of Head Hits Jump as Young Football Players Get Older Findings confirm that these injuries ... 27, 2017 (HealthDay News) -- As kids who play football get older, head hits during play become more ...
Opioid Abuse Jumps 6-Fold for U.S. Youth, Too Few Get Treated
... page: https://medlineplus.gov/news/fullstory_166743.html Opioid Abuse Jumps 6-Fold for U.S. Youth, Too ... June 19, 2017 (HealthDay News) -- The rate of opioid addiction among Americans age 25 and under rose ...
Fractional Fick's Law for the Boundary Driven Exclusion Process with Long Jumps
Bernardin, Cédric; Oviedo Jimenez, Byron
2016-01-01
A fractional Fick's law and fractional hydrostatics for the one dimensional exclusion process with long jumps in contact with infinite reservoirs at different densities on the left and on the right are derived.
Jump Rope Training: Balance and Motor Coordination in Preadolescent Soccer Players
National Research Council Canada - National Science Library
Trecroci, Athos; Cavaggioni, Luca; Caccia, Riccardo; Alberti, Giampietro
2015-01-01
... to the learning soccer-specific skills. Jumping rope is a widely-used and non-specific practical method for the development of athletic conditioning, balance and coordination in several disciplines...
Perceiving action boundaries: Learning effects in perceiving maximum jumping-reach affordances
National Research Council Canada - National Science Library
Ramenzoni, V.C; Davis, T.J; Riley, M.A; Shockley, K
2010-01-01
.... Those estimates were compared with estimates that perceivers made for themselves. In Experiment 1, participants initially underestimated the maximum jumping-reach height both for themselves and for the...
Analysis and design of Markov jump systems with complex transition probabilities
Zhang, Lixian; Shi, Peng; Zhu, Yanzheng
2016-01-01
The book addresses the control issues such as stability analysis, control synthesis and filter design of Markov jump systems with the above three types of TPs, and thus is mainly divided into three parts. Part I studies the Markov jump systems with partially unknown TPs. Different methodologies with different conservatism for the basic stability and stabilization problems are developed and compared. Then the problems of state estimation, the control of systems with time-varying delays, the case involved with both partially unknown TPs and uncertain TPs in a composite way are also tackled. Part II deals with the Markov jump systems with piecewise homogeneous TPs. Methodologies that can effectively handle control problems in the scenario are developed, including the one coping with the asynchronous switching phenomenon between the currently activated system mode and the controller/filter to be designed. Part III focuses on the Markov jump systems with memory TPs. The concept of σ-mean square stability is propo...
Benjaminse, A.; Meijer, M.; Cortes, N.; Gokeler, A.
2014-01-01
BACKGROUND: Neuropsychological capabilities in athletes may be associated with a predisposition to anterior cruciate ligament (ACL) injuries. OBJECTIVE: Assess differences between male and female athletes in jump-landing technique in relation to their neuropsychological capabilities. DESIGN:
Directory of Open Access Journals (Sweden)
Stech M.
2010-02-01
Full Text Available In the paper the results of correlation analysis between of most significance jumping action's indices of high performance polish female volleyball players and their some somatic characteristics (stature, weight and body composition indices: BMI, FATkg, FAT%, FFMkg,FFM%, TBWkg and TBW% are presented. It has been found close correlation between of height of attack jump and stature (r=0,98, weight (r=0,76, FFMkg(r=0,88 and TBWkg (r=0,88. But correlation of height of attack jump with FFM% and TBW% was nonessential. Statistical essential correlation between basic indices of plyometric factor and FAT%, FFM% and TBW% indices (accordingly r = -0,65; 0,65 and 0,66 has been found. The results of the study may be taking into consideration in order to elaboration of effective jumping methods for volleyball players.
Potentiation of vertical jump performance during a snatch pull exercise session.
Chiu, Loren Z F; Salem, George J
2012-12-01
Potentiation has been reported in power tasks immediately following a strength stimulus; however, only whole-body performance has been assessed. To determine the acute effects of weightlifting on vertical jump joint kinetics, performance was assessed before, during, and after snatch pull exercise in male athletes. Jumping was assessed using 3D motion analysis and inverse dynamics. Jump height was enhanced at the midpoint (5.77%; p = .001) and end (5.90%; p Snatch pull exercise elicited acute enhancements in vertical jump performance. At the midpoint of the exercise session, greater work at the knee joint contributed to enhanced performance. At the end of the exercise session, greater work at the ankle contributed to enhanced performance. Consequently, potentiation is not elicited uniformly across joints during multijoint exercise.
Analytical solution to problems of hydraulic jump in horizontal triangular channels
Directory of Open Access Journals (Sweden)
I.M.H. Rashwan
2013-09-01
Full Text Available A hydraulic jump is formed in a channel whenever supercritical flow changes to subcritical flow in a short distance. It can be used in triangular ditch irrigation to raise the downstream water surface. The basic elements and characteristics of the hydraulic jump are provided to aid designers in selecting more practical basins. In the present study, the slope side, discharge and the energy loss in hydraulic jump in horizontal triangular section are known whereas one has to obtain the sequent depths. The specific force and specific energy equations in a horizontal triangular open channel are made dimensionless, writing it for the sequent depths as a function of discharge and head loss. The proposed modes for hydraulic jump elements are of high accuracy and applicable to a wide range of discharge intensity values and initial conditions without any limitations for the assumptions under consideration.
Intra-task variability of trunk coordination during a rate-controlled bipedal dance jump.
Smith, Jo Armour; Siemienski, Adam; Popovich, John M; Kulig, Kornelia
2012-01-01
In this study, we investigated trunk coordination during rate-controlled bipedal vertical dance jumps. The aims of the study were to investigate the pattern of coordination and the magnitude of coordination variability within jump phases and relative to phase-defining events during the jump. Lumbar and thoracic kinematics were collected from seven dancers during a series of jumps at 95 beats per minute. The vector coding technique was used to quantify the pattern and variability of trunk coordination. Coordination was predominantly anti-phase during propulsion and landing. Mean coordination variability peaked just before the landing phase and at the transition from landing to propulsion phases, and was lowest during the propulsion phase just before toe-off. The results indicate that peaks in variability could be explained by task and phase-specific biomechanical demands.
Institute of Scientific and Technical Information of China (English)
蒋义文; 刘禄勤
2003-01-01
The representation of additive functionals and local times for jump Markovprocesses are obtained. The results of uniformly functional moderate deviation and theirapplications to birth-death processes are also presented.
Benjaminse, A.; Meijer, M.; Cortes, N.; Gokeler, A.
2014-01-01
BACKGROUND: Neuropsychological capabilities in athletes may be associated with a predisposition to anterior cruciate ligament (ACL) injuries. OBJECTIVE: Assess differences between male and female athletes in jump-landing technique in relation to their neuropsychological capabilities. DESIGN: Experim
Benjaminse, A.; Meijer, M.; Cortes, N.; Gokeler, A.
2014-01-01
BACKGROUND: Neuropsychological capabilities in athletes may be associated with a predisposition to anterior cruciate ligament (ACL) injuries. OBJECTIVE: Assess differences between male and female athletes in jump-landing technique in relation to their neuropsychological capabilities. DESIGN: Experim
Bilateral contact ground reaction forces and contact times during plyometric drop jumping.
Ball, Nick B; Stock, Christopher G; Scurr, Joanna C
2010-10-01
Drop jumping (DJ) is used in training programs aimed to improve lower extremity explosive power. When performing double-leg drop jumps, it is important to provide an equal stimulus to both legs to ensure balanced development of the lower legs. The aim of this study was to bilaterally analyze the ground reactions forces and temporal components of drop jumping from 3 heights. Ten recreationally active male subjects completed 3 bounce-drop jumps from 3 starting heights (0.2, 0.4, and 0.6 m). Two linked force platforms were used to record left- and right-leg peak vertical force, time to peak force, average force, ground contact time, impulse and time differential. Between-height and between-leg comparisons for each variable were made using a multivariate analysis of variance with post hoc Wilcoxon tests (p vertical forces and temporal components occur; however, shorter contact times were found at the lower heights.