Microscopic models of quantum-jump superoperators
International Nuclear Information System (INIS)
Dodonov, A.V.; Mizrahi, S.S.; Dodonov, V.V.
2005-01-01
We discuss the quantum-jump operation in an open system and show that jump superoperators related to a system under measurement can be derived from the interaction of that system with a quantum measurement apparatus. We give two examples for the interaction of a monochromatic electromagnetic field in a cavity (the system) with two-level atoms and with a harmonic oscillator (representing two different kinds of detectors). We show that the derived quantum-jump superoperators have a 'nonlinear' form Jρ=γ diag[F(n)aρa † F(n)], where the concrete form of the function F(n) depends on assumptions made about the interaction between the system and detector. Under certain conditions the asymptotical power-law dependence F(n)=(n+1) -β is obtained. A continuous transition to the standard Srinivas-Davies form of the quantum-jump superoperator (corresponding to β=0) is shown
Decoherence in quantum lossy systems: superoperator and matrix techniques
Yazdanpanah, Navid; Tavassoly, Mohammad Kazem; Moya-Cessa, Hector Manuel
2017-06-01
Due to the unavoidably dissipative interaction between quantum systems with their environments, the decoherence flows inevitably into the systems. Therefore, to achieve a better understanding on how decoherence affects on the damped systems, a fundamental investigation of master equation seems to be required. In this regard, finding out the missed information which has been lost due to irreversibly of the dissipative systems, is also of practical importance in quantum information science. Motivating by these facts, in this work we want to use superoperator and matrix techniques, by which we are able to illustrate two methods to obtain the explicit form of density operators corresponding to damped systems at arbitrary temperature T ≥ 0. To establish the potential abilities of the suggested methods, we apply them to deduce the density operator of some practical well-known quantum systems. Using the superoperator techniques, at first we obtain the density operator of a damped system which includes a qubit interacting with a single-mode quantized field within an optical cavity. As the second system, we study the decoherence of a quantized field within an optical damped cavity. We also use our proposed matrix method to study the decoherence of a system which includes two qubits in the interaction with each other via dipole-dipole interaction and at the same time with a quantized field in a lossy cavity. The influences of dissipation on the decoherence of dynamical properties of these systems are also numerically investigated. At last, the advantages of the proposed superoperator techniques in comparison with matrix method are explained.
International Nuclear Information System (INIS)
Cook, R.J.
1988-01-01
This paper answers the title question by giving an operational definition of quantum jumps based on measurement theory. This definition forms the basis of a theory of quantum jumps which leads to a number of testable predictions. Experiments are proposed to test the theory. The suggested experiments also test the quantum Zeno paradox, i.e., they test the proposition that frequent observation of a quantum system inhibits quantum jumps in that system. (orig.)
Quantum jumps are more quantum than quantum diffusion
International Nuclear Information System (INIS)
Daryanoosh, Shakib; M Wiseman, Howard
2014-01-01
It was recently argued (Wiseman and Gambetta 2012 Phys. Rev. Lett. 108 220402) that the stochastic dynamics (jumps or diffusion) of an open quantum system are not inherent to the system, but rather depend on the existence and nature of a distant detector. The proposed experimental tests involved homodyne detection, giving rise to quantum diffusion, and required efficiencies η of well over 50%. Here we prove that this requirement (η>0.5) is universal for diffusive-type detection, even if the system is coupled to multiple baths. However, this no-go theorem does not apply to quantum jumps, and we propose a test involving a qubit with jump-type detectors, with a threshold efficiency of only 37%. That is, quantum jumps are ‘more quantum’, and open the way to practical experimental tests. Our scheme involves a novel sort of adaptive monitoring scheme on a system coupled to two baths. (paper)
Tests for nonrandomness in quantum jumps
International Nuclear Information System (INIS)
Berkeland, D.J.; Raymondson, D.A.; Tassin, V.M.
2004-01-01
In a fundamental test of quantum mechanics, we have observed 228 000 quantum jumps of a single trapped and laser cooled 88 Sr + ion. This represents a statistical increase of two orders of magnitude over previous similar analyses of quantum jumps. Compared to other searches for nonrandomness in quantum-mechanical processes, using quantum jumps simplifies the interpretation of data by eliminated multiparticle effects and providing near-unit detection efficiency of transitions. We measure the fractional reduction in the entropy of information to be -4 when the value of any interval between quantum jumps is known. We also find that the number of runs of successively increasing or decreasing interval times agrees with the theoretically expected values. Furthermore, we analyze 238 000 quantum jumps from two simultaneously confined ions and find that the number of apparently coincidental transitions is as expected. Finally, we observe 8400 spontaneous decays of two simultaneously trapped ions and find that the number of apparently coincidental decays from the metastable state agrees with the expected value. We find no evidence for short- or long-term correlations in the intervals of the quantum jumps or in the decay of the quantum states, in agreement with quantum theory
Detected-jump-error-correcting quantum codes, quantum error designs, and quantum computation
International Nuclear Information System (INIS)
Alber, G.; Mussinger, M.; Beth, Th.; Charnes, Ch.; Delgado, A.; Grassl, M.
2003-01-01
The recently introduced detected-jump-correcting quantum codes are capable of stabilizing qubit systems against spontaneous decay processes arising from couplings to statistically independent reservoirs. These embedded quantum codes exploit classical information about which qubit has emitted spontaneously and correspond to an active error-correcting code embedded in a passive error-correcting code. The construction of a family of one-detected-jump-error-correcting quantum codes is shown and the optimal redundancy, encoding, and recovery as well as general properties of detected-jump-error-correcting quantum codes are discussed. By the use of design theory, multiple-jump-error-correcting quantum codes can be constructed. The performance of one-jump-error-correcting quantum codes under nonideal conditions is studied numerically by simulating a quantum memory and Grover's algorithm
Timeless Approach to Quantum Jumps
Directory of Open Access Journals (Sweden)
Ignazio Licata
2015-10-01
Full Text Available According to the usual quantum description, the time evolution of the quantum state is continuous and deterministic except when a discontinuous and indeterministic collapse of state vector occurs. The collapse has been a central topic since the origin of the theory, although there are remarkable theoretical proposals to understand its nature, such as the Ghirardi–Rimini–Weber. Another possibility could be the assimilation of collapse with the now experimentally well established phenomenon of quantum jump, postulated by Bohr already in 1913. The challenge of nonlocality offers an opportunity to reconsider the quantum jump as a fundamental element of the logic of the physical world, rather than a subsidiary accident. We propose here a simple preliminary model that considers quantum jumps as processes of entry to and exit from the usual temporal domain to a timeless vacuum, without contradicting the quantum relativistic formalism, and we present some potential connections with particle physics. Quanta 2015; 4: 10–26.
International Nuclear Information System (INIS)
Harbola, U.; Mukamel, S.
2008-01-01
Nonequilibrium Green's functions provide a powerful tool for computing the dynamical response and particle exchange statistics of coupled quantum systems. We formulate the theory in terms of the density matrix in Liouville space and introduce superoperator algebra that greatly simplifies the derivation and the physical interpretation of all quantities. Expressions for various observables are derived directly in real time in terms of superoperator nonequilibrium Green's functions (SNGF), rather than the artificial time-loop required in Schwinger's Hilbert-space formulation. Applications for computing interaction energies, charge densities, average currents, current induced fluorescence, electroluminescence and current fluctuation (electron counting) statistics are discussed
Jump probabilities in the non-Markovian quantum jump method
International Nuclear Information System (INIS)
Haerkoenen, Kari
2010-01-01
The dynamics of a non-Markovian open quantum system described by a general time-local master equation is studied. The propagation of the density operator is constructed in terms of two processes: (i) deterministic evolution and (ii) evolution of a probability density functional in the projective Hilbert space. The analysis provides a derivation for the jump probabilities used in the recently developed non-Markovian quantum jump (NMQJ) method (Piilo et al 2008 Phys. Rev. Lett. 100 180402).
Quantum jumps on Anderson attractors
Yusipov, I. I.; Laptyeva, T. V.; Ivanchenko, M. V.
2018-01-01
In a closed single-particle quantum system, spatial disorder induces Anderson localization of eigenstates and halts wave propagation. The phenomenon is vulnerable to interaction with environment and decoherence that is believed to restore normal diffusion. We demonstrate that for a class of experimentally feasible non-Hermitian dissipators, which admit signatures of localization in asymptotic states, quantum particle opts between diffusive and ballistic regimes, depending on the phase parameter of dissipators, with sticking about localization centers. In a diffusive regime, statistics of quantum jumps is non-Poissonian and has a power-law interval, a footprint of intermittent locking in Anderson modes. Ballistic propagation reflects dispersion of an ordered lattice and introduces the second timescale for jumps, resulting in non-nonmonotonous probability distribution. Hermitian dephasing dissipation makes localization features vanish, and Poissonian jump statistics along with normal diffusion are recovered.
International Nuclear Information System (INIS)
Schulman, L.S.
1997-01-01
Although the only time scale one ordinarily associates with a quantum transition is its lifetime, observations of ''quantum jumps'' in recent years show that the actual transition time is much shorter. I define a ''jump time'' as the time scale such that perturbations occurring at intervals of this duration affect the decay. In terms of the ''Zeno time'' (related to the second moment of the Hamiltonian) the jump time is τ J is identical to τ 2 Z /τ L . Corroboration is given. I also show that observing the ''jumping'' will not seriously affect the system lifetime, but will affect the linewidth. This is consistent with Bohr's ideas on measurement as well as with a heuristic time-energy uncertainty principle. (author)
Quantum-capacity-approaching codes for the detected-jump channel
International Nuclear Information System (INIS)
Grassl, Markus; Wei Zhaohui; Ji Zhengfeng; Zeng Bei
2010-01-01
The quantum-channel capacity gives the ultimate limit for the rate at which quantum data can be reliably transmitted through a noisy quantum channel. Degradable quantum channels are among the few channels whose quantum capacities are known. Given the quantum capacity of a degradable channel, it remains challenging to find a practical coding scheme which approaches capacity. Here we discuss code designs for the detected-jump channel, a degradable channel with practical relevance describing the physics of spontaneous decay of atoms with detected photon emission. We show that this channel can be used to simulate a binary classical channel with both erasures and bit flips. The capacity of the simulated classical channel gives a lower bound on the quantum capacity of the detected-jump channel. When the jump probability is small, it almost equals the quantum capacity. Hence using a classical capacity-approaching code for the simulated classical channel yields a quantum code which approaches the quantum capacity of the detected-jump channel.
Sub-Poissonian statistics of quantum jumps in single molecule or atomic ion
International Nuclear Information System (INIS)
Osad'ko, I.S.; Gus'kov, D.N.
2007-01-01
A theory for statistics of quantum jumps in single molecule or ion driven by continues wave laser field is developed. These quantum jumps can relate to nonradiative singlet-triplet transitions in a molecule or to on → off jumps in a single ion with shelving processes. Distribution function w N (T) of quantum jumps in time interval T is found. Computer simulation of quantum jumps is realized. Statistical treatment of simulated jumps reveals sub-Poissonian statistics of quantum jumps. The theoretical distribution function w N (T) fits well the distribution of jumps found from simulated data. Experimental data on quantum jumps found in experiments with single Hg + ion are described by the function w N (T) well
International Nuclear Information System (INIS)
Carmichael, H.J.
2015-01-01
This paper cannot provide anything like a complete overview of quantum optics in New Zealand. The scope over 40 years is far too broad and the number of players far too large. Nevertheless, the story of quantum jumps, from the days of the Old Quantum Theory up to the present, serves to highlight some small part of the New Zealand experience. It also offers an encounter with the oddities of light as a quantum mechanical 'something', oddities that the gallant proposers of technologies for the future aim to exploit. (author).
Projected evolution superoperators and the density operator
International Nuclear Information System (INIS)
Turner, R.E.; Dahler, J.S.; Snider, R.F.
1982-01-01
The projection operator method of Zwanzig and Feshbach is used to construct the time dependent density operator associated with a binary scattering event. The formula developed to describe this time dependence involves time-ordered cosine and sine projected evolution (memory) superoperators. Both Schroedinger and interaction picture results are presented. The former is used to demonstrate the equivalence of the time dependent solution of the von Neumann equation and the more familiar frequency dependent Laplace transform solution. For two particular classes of projection superoperators projected density operators are shown to be equivalent to projected wave functions. Except for these two special cases, no projected wave function analogs of projected density operators exist. Along with the decoupled-motions approximation, projected interaction picture density operators are applied to inelastic scattering events. Simple illustrations are provided of how this formalism is related to previously established results for two-state processes, namely, the theory of resonant transfer events, the first order Magnus approximation, and the Landau-Zener theory
Superoperators in the dual model with coloured quarks
International Nuclear Information System (INIS)
Manida, S.N.
1978-01-01
The derivation of the dual model with coloured quarks is considered. The model is represented as a superoperator generalization of the Bardakci-Halpern model. It is shown that the three-regeon vertex of the model appears to be more compact and transparent
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)
Memory for Light as a Quantum Process
International Nuclear Information System (INIS)
Lobino, M.; Kupchak, C.; Lvovsky, A. I.; Figueroa, E.
2009-01-01
We report complete characterization of an optical memory based on electromagnetically induced transparency. We recover the superoperator associated with the memory, under two different working conditions, by means of a quantum process tomography technique that involves storage of coherent states and their characterization upon retrieval. In this way, we can predict the quantum state retrieved from the memory for any input, for example, the squeezed vacuum or the Fock state. We employ the acquired superoperator to verify the nonclassicality benchmark for the storage of a Gaussian distributed set of coherent states.
Quantum jumps in a three-level system
International Nuclear Information System (INIS)
Javanainen, J.
1986-01-01
The authors study fluorescence in a scheme which is easy to treat theoretically: a two-level system driven by a laser and a third metastable state such that slow spontaneous transitions take place both from the excited state of a two-level system to the metastable state and from the metastable state to the ground state of the two-level system. With the aid of the quantum regression theorem the authors calculate the whole photon counting statistics at a detector which records scattering of the laser photons. In the limit of high intensity of the laser, the statistics of photon counts is found to be the same as the statistics of a two-state Markov jumps process. Thus, if the sequence of photon counts can be interpreted as a realization of a stochastic process, in a single experimental run the fluorescence should abruptly turn on and off for random intervals of time. The result is the same as given by the quantum-jump argument
Jumping magneto-electric states of electrons in semiconductor multiple quantum wells
International Nuclear Information System (INIS)
Pfeffer, Pawel; Zawadzki, Wlodek
2011-01-01
Orbital and spin electron states in semiconductor multiple quantum wells in the presence of an external magnetic field transverse to the growth direction are considered. Rectangular wells of GaAs/GaAlAs and InAs/AlSb are taken as examples. It is shown that, in addition to magneto-electric states known from one-well systems, there appear magneto-electric states having a much stronger dependence of energies on a magnetic field and exhibiting an interesting anti-crossing behavior. The origin of these states is investigated and it is shown that the strong field dependence of the energies is related to an unusual 'jumping' behavior of their wavefunctions between quantum wells as the field increases. The ways of investigating the jumping states by means of interband magneto-luminescence transitions or intraband cyclotron-like transitions are considered and it is demonstrated that the jumping states can be observed. The spin g factors of electrons in the jumping states are calculated using the real values of the spin–orbit interaction and bands' nonparabolicity for the semiconductors in question. It is demonstrated that the jumping states offer a wide variety of the spin g factors
Non-Poissonian quantum jumps of a fluxonium qubit due to quasiparticle excitations.
Vool, U; Pop, I M; Sliwa, K; Abdo, B; Wang, C; Brecht, T; Gao, Y Y; Shankar, S; Hatridge, M; Catelani, G; Mirrahimi, M; Frunzio, L; Schoelkopf, R J; Glazman, L I; Devoret, M H
2014-12-12
As the energy relaxation time of superconducting qubits steadily improves, nonequilibrium quasiparticle excitations above the superconducting gap emerge as an increasingly relevant limit for qubit coherence. We measure fluctuations in the number of quasiparticle excitations by continuously monitoring the spontaneous quantum jumps between the states of a fluxonium qubit, in conditions where relaxation is dominated by quasiparticle loss. Resolution on the scale of a single quasiparticle is obtained by performing quantum nondemolition projective measurements within a time interval much shorter than T₁, using a quantum-limited amplifier (Josephson parametric converter). The quantum jump statistics switches between the expected Poisson distribution and a non-Poissonian one, indicating large relative fluctuations in the quasiparticle population, on time scales varying from seconds to hours. This dynamics can be modified controllably by injecting quasiparticles or by seeding quasiparticle-trapping vortices by cooling down in a magnetic field.
Resonant Pump-dump Quantum Control of Solvated Dye Molecules with Phase Jumps
Konar, Arkaprabha; Lozovoy, Vadim; Dantus, Marcos
2014-03-01
Quantum coherent control of two photon and multiphoton excitation processes in atomic and condensed phase systems employing phase jumps has been well studied and understood. Here we demonstrate coherent quantum control of a two photon resonant pump-dump process in a complex solvated dye molecule. Phase jump in the frequency domain via a pulse shaper is employed to coherently enhance the stimulated emission by an order of magnitude when compared to transform limited pulses. Red shifted stimulated emission from successive low energy Stokes shifted excited states leading to narrowband emission are observed upon scanning the pi step across the excitation spectrum. A binary search space routine was also employed to investigate the effects of other types of phase jumps on stimulated emission and to determine the optimum phase that maximizes the emission. Understanding the underlying mechanism of this kind of enhancement will guide us in designing pulse shapes for enhancing stimulated emission, which can be further applied in the field of imaging.
Density operators in quantum mechanics
International Nuclear Information System (INIS)
Burzynski, A.
1979-01-01
A brief discussion and resume of density operator formalism in the way it occurs in modern physics (in quantum optics, quantum statistical physics, quantum theory of radiation) is presented. Particularly we emphasize the projection operator method, application of spectral theorems and superoperators formalism in operator Hilbert spaces (Hilbert-Schmidt type). The paper includes an appendix on direct sums and direct products of spaces and operators, and problems of reducibility for operator class by using the projection operators. (author)
International Nuclear Information System (INIS)
Fischer, Ernst Peter
2010-01-01
Who doesn't know the quantum jumps, which politicians like to promise in their speeched? But what the quantum jump in physics precisely means know only very few people. For this brings no enormous progress, but is in an ironical way the smallest change, which an atom can perform. This and other misunderstandings discovers Professor Ernst Peter Fischer in his new book. With funny comparisons from daily life he leads even laymen via ''The Backstairs to the Quantum Jump'' to the most important physical results. For this he characterizes important physicists like Niels Bohr, Alber Einstein, or Max Planck, and enters not only their discoveries, but also their personalities behind the genius.
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.
Quantum jump from singularity to outside of black hole
International Nuclear Information System (INIS)
Dündar, Furkan Semih; Hajian, Kamal
2016-01-01
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.
International Nuclear Information System (INIS)
Bruzda, Wojciech; Cappellini, Valerio; Sommers, Hans-Juergen; Zyczkowski, Karol
2009-01-01
We define a natural ensemble of trace preserving, completely positive quantum maps and present algorithms to generate them at random. Spectral properties of the superoperator Φ associated with a given quantum map are investigated and a quantum analogue of the Frobenius-Perron theorem is proved. We derive a general formula for the density of eigenvalues of Φ and show the connection with the Ginibre ensemble of real non-symmetric random matrices. Numerical investigations of the spectral gap imply that a generic state of the system iterated several times by a fixed generic map converges exponentially to an invariant state
Perturbative approach to Markovian open quantum systems.
Li, Andy C Y; Petruccione, F; Koch, Jens
2014-05-08
The exact treatment of Markovian open quantum systems, when based on numerical diagonalization of the Liouville super-operator or averaging over quantum trajectories, is severely limited by Hilbert space size. Perturbation theory, standard in the investigation of closed quantum systems, has remained much less developed for open quantum systems where a direct application to the Lindblad master equation is desirable. We present such a perturbative treatment which will be useful for an analytical understanding of open quantum systems and for numerical calculation of system observables which would otherwise be impractical.
DEFF Research Database (Denmark)
Sannino, Francesco
2013-01-01
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....
Zurek, Wojciech Hubert
2018-07-13
The emergence of the classical world from the quantum substrate of our Universe is a long-standing conundrum. In this paper, I describe three insights into the transition from quantum to classical that are based on the recognition of the role of the environment. I begin with the derivation of preferred sets of states that help to define what exists-our everyday classical reality. They emerge as a result of the breaking of the unitary symmetry of the Hilbert space which happens when the unitarity of quantum evolutions encounters nonlinearities inherent in the process of amplification-of replicating information. This derivation is accomplished without the usual tools of decoherence, and accounts for the appearance of quantum jumps and the emergence of preferred pointer states consistent with those obtained via environment-induced superselection, or einselection The pointer states obtained in this way determine what can happen-define events-without appealing to Born's Rule for probabilities. Therefore, p k =| ψ k | 2 can now be deduced from the entanglement-assisted invariance, or envariance -a symmetry of entangled quantum states. With probabilities at hand, one also gains new insights into the foundations of quantum statistical physics. Moreover, one can now analyse the information flows responsible for decoherence. These information flows explain how the perception of objective classical reality arises from the quantum substrate: the effective amplification that they represent accounts for the objective existence of the einselected states of macroscopic quantum systems through the redundancy of pointer state records in their environment-through quantum Darwinism This article is part of a discussion meeting issue 'Foundations of quantum mechanics and their impact on contemporary society'. © 2018 The Author(s).
Dropout dynamics in pulsed quantum dot lasers due to mode jumping
Energy Technology Data Exchange (ETDEWEB)
Sokolovskii, G. S.; Dudelev, V. V.; Deryagin, A. G.; Novikov, I. I.; Maximov, M. V.; Ustinov, V. M.; Kuchinskii, V. I. [Ioffe Physical-Technical Institute, St. Petersburg (Russian Federation); Viktorov, E. A. [National Research University of Information Technologies, Mechanics and Optics, Saint Petersburg (Russian Federation); Optique Nonlinéaire Théorique, Campus Plaine CP 231, 1050 Bruxelles (Belgium); Applied Physics Research Group (APHY), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium); Abusaa, M. [Applied Physics Research Group (APHY), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium); Arab American University, Jenin, Palestine (Country Unknown); Danckaert, J. [Applied Physics Research Group (APHY), Vrije Universiteit Brussel, Pleinlaan 2, B-1050 Brussels (Belgium); Kolykhalova, E. D. [St. Petersburg State Electrotechnical University “LETI,” St. Petersburg (Russian Federation); Soboleva, K. K. [St. Petersburg State Polytechnical University, St. Petersburg (Russian Federation); Zhukov, A. E. [Academic University, St. Petersburg (Russian Federation); Sibbett, W. [University of St. Andrews, St. Andrews (United Kingdom); Rafailov, E. U. [Aston Institute of Photonic Technologies, Aston University, Birmingham (United Kingdom); Erneux, T. [Optique Nonlinéaire Théorique, Campus Plaine CP 231, 1050 Bruxelles (Belgium)
2015-06-29
We examine the response of a pulse pumped quantum dot laser both experimentally and numerically. As the maximum of the pump pulse comes closer to the excited-state threshold, the output pulse shape becomes unstable and leads to dropouts. We conjecture that these instabilities result from an increase of the linewidth enhancement factor α as the pump parameter comes close to the excitated state threshold. In order to analyze the dynamical mechanism of the dropout, we consider two cases for which the laser exhibits either a jump to a different single mode or a jump to fast intensity oscillations. The origin of these two instabilities is clarified by a combined analytical and numerical bifurcation diagram of the steady state intensity modes.
Dropout dynamics in pulsed quantum dot lasers due to mode jumping
International Nuclear Information System (INIS)
Sokolovskii, G. S.; Dudelev, V. V.; Deryagin, A. G.; Novikov, I. I.; Maximov, M. V.; Ustinov, V. M.; Kuchinskii, V. I.; Viktorov, E. A.; Abusaa, M.; Danckaert, J.; Kolykhalova, E. D.; Soboleva, K. K.; Zhukov, A. E.; Sibbett, W.; Rafailov, E. U.; Erneux, T.
2015-01-01
We examine the response of a pulse pumped quantum dot laser both experimentally and numerically. As the maximum of the pump pulse comes closer to the excited-state threshold, the output pulse shape becomes unstable and leads to dropouts. We conjecture that these instabilities result from an increase of the linewidth enhancement factor α as the pump parameter comes close to the excitated state threshold. In order to analyze the dynamical mechanism of the dropout, we consider two cases for which the laser exhibits either a jump to a different single mode or a jump to fast intensity oscillations. The origin of these two instabilities is clarified by a combined analytical and numerical bifurcation diagram of the steady state intensity modes
International Nuclear Information System (INIS)
Erber, T.; Hammerling, P.; Hockney, G.; Porrati, M.; Putterman, S.; La Jolla Institute, La Jolla, California 92037; Department of Physics, University of California, Los Angeles, California 90024)
1989-01-01
When a single trapped 198 Hg + ion is illuminated by two lasers, each tuned to an approximate transition, the resulting fluorescence switches on and off in a series of pulses resembling a bistable telegraph. This intermittent fluorescence can also be obtained by optical pumping with a single laser. Quantum jumps between successive atomic levels may be traced directly with multiple-resonance fluorescence. Atomic transition rates and photon antibunching distributions can be inferred from the pulse statistics and compared with quantum theory. Stochastic tests also indicate that the quantum telegraphs are good random number generators. During periods when the fluorescence is switched off, the radiationless atomic currents that generate the telegraph signals can be adjusted by varying the laser illumination: if this coherent evolution of the wave functions is sustained over sufficiently long time intervals, novel interactive precision measurements, near the limits of the time-energy uncertainty relations, are possible. Copyright 1989 Academic Press, Inc
Organic molecule fluorescence as an experimental test-bed for quantum jumps in thermodynamics.
Browne, Cormac; Farrow, Tristan; Dahlsten, Oscar C O; Taylor, Robert A; Vlatko, Vedral
2017-08-01
We demonstrate with an experiment how molecules are a natural test bed for probing fundamental quantum thermodynamics. Single-molecule spectroscopy has undergone transformative change in the past decade with the advent of techniques permitting individual molecules to be distinguished and probed. We demonstrate that the quantum Jarzynski equality for heat is satisfied in this set-up by considering the time-resolved emission spectrum of organic molecules as arising from quantum jumps between states. This relates the heat dissipated into the environment to the free energy difference between the initial and final state. We demonstrate also how utilizing the quantum Jarzynski equality allows for the detection of energy shifts within a molecule, beyond the relative shift.
Hidden Markov Model of atomic quantum jump dynamics in an optically probed cavity
DEFF Research Database (Denmark)
Gammelmark, S.; Molmer, K.; Alt, W.
2014-01-01
We analyze the quantum jumps of an atom interacting with a cavity field. The strong atom- field interaction makes the cavity transmission depend on the time dependent atomic state, and we present a Hidden Markov Model description of the atomic state dynamics which is conditioned in a Bayesian...... manner on the detected signal. We suggest that small variations in the observed signal may be due to spatial motion of the atom within the cavity, and we represent the atomic system by a number of hidden states to account for both the small variations and the internal state jump dynamics. In our theory...
Analyzing quantum jumps of one and two atoms strongly coupled to an optical cavity
DEFF Research Database (Denmark)
Reick, Sebastian; Mølmer, Klaus; Alt, Wolfgang
2010-01-01
We induce quantum jumps between the hyperfine ground states of one and two cesium atoms, strongly coupled to the mode of a high-finesse optical resonator, and analyze the resulting random telegraph signals. We identify experimental parameters to deduce the atomic spin state nondestructively from ...
Henkel, Christof
2017-03-01
We present an agent behavior based microscopic model that induces jumps, spikes and high volatility phases in the price process of a traded asset. We transfer dynamics of thermally activated jumps of an unexcited/excited two state system discussed in the context of quantum mechanics to agent socio-economic behavior and provide microfoundations. After we link the endogenous agent behavior to price dynamics we establish the circumstances under which the dynamics converge to an Itô-diffusion price processes in the large market limit.
Quantum computer with mixed states and four-valued logic
International Nuclear Information System (INIS)
Tarasov, Vasily E.
2002-01-01
In this paper we discuss a model of quantum computer in which a state is an operator of density matrix and gates are general quantum operations, not necessarily unitary. A mixed state (operator of density matrix) of n two-level quantum systems is considered as an element of 4 n -dimensional operator Hilbert space (Liouville space). It allows us to use a quantum computer model with four-valued logic. The gates of this model are general superoperators which act on n-ququat state. Ququat is a quantum state in a four-dimensional (operator) Hilbert space. Unitary two-valued logic gates and quantum operations for an n-qubit open system are considered as four-valued logic gates acting on n-ququats. We discuss properties of quantum four-valued logic gates. In the paper we study universality for quantum four-valued logic gates. (author)
Quantum-statistical kinetic equations
International Nuclear Information System (INIS)
Loss, D.; Schoeller, H.
1989-01-01
Considering a homogeneous normal quantum fluid consisting of identical interacting fermions or bosons, the authors derive an exact quantum-statistical generalized kinetic equation with a collision operator given as explicit cluster series where exchange effects are included through renormalized Liouville operators. This new result is obtained by applying a recently developed superoperator formalism (Liouville operators, cluster expansions, symmetrized projectors, P q -rule, etc.) to nonequilibrium systems described by a density operator ρ(t) which obeys the von Neumann equation. By means of this formalism a factorization theorem is proven (being essential for obtaining closed equations), and partial resummations (leading to renormalized quantities) are performed. As an illustrative application, the quantum-statistical versions (including exchange effects due to Fermi-Dirac or Bose-Einstein statistics) of the homogeneous Boltzmann (binary collisions) and Choh-Uhlenbeck (triple collisions) equations are derived
Optimising stochastic trajectories in exact quantum jump approaches of interacting systems
International Nuclear Information System (INIS)
Lacroix, D.
2004-11-01
The standard methods used to substitute the quantum dynamics of two interacting systems by a quantum jump approach based on the Stochastic Schroedinger Equation (SSE) are described. It turns out that for a given situation, there exists an infinite number of SSE reformulation. This fact is used to propose general strategies to optimise the stochastic paths in order to reduce the statistical fluctuations. In this procedure, called the 'adaptative noise method', a specific SSE is obtained for which the noise depends explicitly on both the initial state and on the properties of the interaction Hamiltonian. It is also shown that this method can be further improved by the introduction of a mean-field dynamics. The different optimisation procedures are illustrated quantitatively in the case of interacting spins. A significant reduction of the statistical fluctuations is obtained. Consequently, a much smaller number of trajectories is needed to accurately reproduce the exact dynamics as compared to the standard SSE method. (author)
International Nuclear Information System (INIS)
Grinberg, H.
1983-11-01
The projection operator method of Zwanzig and Feshbach is used to construct the time-dependent field operators in the interaction picture. The formula developed to describe the time dependence involves time-ordered cosine and sine projected evolution (memory) superoperators, from which a master equation for the interaction-picture single-particle Green's function in a Liouville space is derived. (author)
Asymptotic evolution of quantum Markov chains
Energy Technology Data Exchange (ETDEWEB)
Novotny, Jaroslav [FNSPE, CTU in Prague, 115 19 Praha 1 - Stare Mesto (Czech Republic); Alber, Gernot [Institut fuer Angewandte Physik, Technische Universitaet Darmstadt, D-64289 Darmstadt (Germany)
2012-07-01
The iterated quantum operations, so called quantum Markov chains, play an important role in various branches of physics. They constitute basis for many discrete models capable to explore fundamental physical problems, such as the approach to thermal equilibrium, or the asymptotic dynamics of macroscopic physical systems far from thermal equilibrium. On the other hand, in the more applied area of quantum technology they also describe general characteristic properties of quantum networks or they can describe different quantum protocols in the presence of decoherence. A particularly, an interesting aspect of these quantum Markov chains is their asymptotic dynamics and its characteristic features. We demonstrate there is always a vector subspace (typically low-dimensional) of so-called attractors on which the resulting superoperator governing the iterative time evolution of quantum states can be diagonalized and in which the asymptotic quantum dynamics takes place. As the main result interesting algebraic relations are presented for this set of attractors which allow to specify their dual basis and to determine them in a convenient way. Based on this general theory we show some generalizations concerning the theory of fixed points or asymptotic evolution of random quantum operations.
Kato expansion in quantum canonical perturbation theory
International Nuclear Information System (INIS)
Nikolaev, Andrey
2016-01-01
This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.
Kato expansion in quantum canonical perturbation theory
Energy Technology Data Exchange (ETDEWEB)
Nikolaev, Andrey, E-mail: Andrey.Nikolaev@rdtex.ru [Institute of Computing for Physics and Technology, Protvino, Moscow Region, Russia and RDTeX LTD, Moscow (Russian Federation)
2016-06-15
This work establishes a connection between canonical perturbation series in quantum mechanics and a Kato expansion for the resolvent of the Liouville superoperator. Our approach leads to an explicit expression for a generator of a block-diagonalizing Dyson’s ordered exponential in arbitrary perturbation order. Unitary intertwining of perturbed and unperturbed averaging superprojectors allows for a description of ambiguities in the generator and block-diagonalized Hamiltonian. We compare the efficiency of the corresponding computational algorithm with the efficiencies of the Van Vleck and Magnus methods for high perturbative orders.
Energy Technology Data Exchange (ETDEWEB)
Fischer, Ernst Peter
2010-07-01
Who doesn't know the quantum jumps, which politicians like to promise in their speeched? But what the quantum jump in physics precisely means know only very few people. For this brings no enormous progress, but is in an ironical way the smallest change, which an atom can perform. This and other misunderstandings discovers Professor Ernst Peter Fischer in his new book. With funny comparisons from daily life he leads even laymen via ''The Backstairs to the Quantum Jump'' to the most important physical results. For this he characterizes important physicists like Niels Bohr, Alber Einstein, or Max Planck, and enters not only their discoveries, but also their personalities behind the genius.
International Nuclear Information System (INIS)
Fischer, Ernst Peter
2015-01-01
It's madness, yet there is method. The physical phenomenon of the quantum jump has already brought some well-known physicists at the edge of dispair. Then nothing seems to be such illogical, undetermined, and unpredictable as the behaviour of the atoms that ultimatively form our world. The renowned historian of sciences Ernst Peter Fischer tells the fascinating story of quantum physics by means of poignant portraits of selected researchers like Max Planck, Werner Heisenberg, Richard P. Feynman, and ''Mr. Beam'' Anton Zeilinger. A great story of science a bout the smallest particles of the nature.
Quantum operations that cannot be implemented using a small mixed environment
International Nuclear Information System (INIS)
Zalka, Christof; Rieffel, Eleanor
2002-01-01
To implement any quantum operation (a.k.a. ''superoperator'' or ''CP map'') on a d-dimensional quantum system, it is enough to apply a suitable overall unitary transformation to the system and a d 2 -dimensional environment which is initialized in a fixed pure state. It has been suggested that a d-dimensional environment might be enough if we could initialize the environment in a mixed state of our choosing. In this note we show with elementary means that certain explicit quantum operations cannot be realized in this way. Our counterexamples map some pure states to pure states, giving strong and easily manageable conditions on the overall unitary transformation. Everything works in the more general setting of quantum operations from d-dimensional to d ' -dimensional spaces, so we place our counterexamples within this more general framework
Lorenzetti, Silvio; Ammann, Fabian; Windmüller, Sabrina; Häberle, Ramona; Müller, Sören; Gross, Micah; Plüss, Michael; Plüss, Stefan; Schödler, Berni; Hübner, Klaus
2017-11-22
As hill jumps are very time-consuming, ski jumping athletes often perform various imitation jumps during training. The performed jumps should be similar to hill jumps, but a direct comparison of the kinetic and kinematic parameters has not been performed yet. Therefore, this study aimed to correlate 11 common parameters during hill jumps (Oberstdorf Germany), squat jumps (wearing indoor shoes), and various imitation jumps (rolling 4°, rolling flat, static; jumping equipment or indoor shoes) on a custom-built instrumented vehicle with a catch by the coach. During the performed jumps, force and video data of the take-off of 10 athletes were measured. The imitation and squat jumps were then ranked. The main difference between the hill jumps and the imitation and squat jumps is the higher maximal force loading rate during the hill jumps. Imitation jumps performed on a rolling platform, on flat ground were the most similar to hill jumps in terms of the force-time, and leg joint kinematic properties. Thus, non-hill jumps with a technical focus should be performed from a rolling platform with a flat inrun with normal indoor shoes or jumping equipment, and high normal force loading rates should be the main focus of imitation training.
Quantum computing with incoherent resources and quantum jumps.
Santos, M F; Cunha, M Terra; Chaves, R; Carvalho, A R R
2012-04-27
Spontaneous emission and the inelastic scattering of photons are two natural processes usually associated with decoherence and the reduction in the capacity to process quantum information. Here we show that, when suitably detected, these photons are sufficient to build all the fundamental blocks needed to perform quantum computation in the emitting qubits while protecting them from deleterious dissipative effects. We exemplify this by showing how to efficiently prepare graph states for the implementation of measurement-based quantum computation.
Quantum Darwinism, Decoherence, and the Randomness of Quantum Jumps
Energy Technology Data Exchange (ETDEWEB)
Zurek, Wojciech H. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-06-05
Tracing flows of information in our quantum Universe explains why we see the world as classical. Quantum principle of superposition decrees every combination of quantum states a legal quantum state. This is at odds with our experience. Decoherence selects preferred pointer states that survive interaction with the environment. They are localized and effectively classical. They persist while their superpositions decohere. Here we consider emergence of `the classical' starting at a more fundamental pre-decoherence level, tracing the origin of preferred pointer states and deducing their probabilities from the core quantum postulates. We also explore role of the environment as medium through which observers acquire information. This mode of information transfer leads to perception of objective classical reality.
Drop jumping. I. The influence of jumping technique on the biomechanics of jumping
Bobbert, M F; Huijing, P A; van Ingen Schenau, G J
In the literature, drop jumping is advocated as an effective exercise for athletes who prepare themselves for explosive activities. When executing drop jumps, different jumping techniques can be used. In this study, the influence of jumping technique on the biomechanics of jumping is investigated.
Barker, Leland A; Harry, John R; Mercer, John A
2018-01-01
Barker, LA, Harry, JR, and Mercer, JA. Relationships between countermovement jump ground reaction forces and jump height, reactive strength index, and jump time. J Strength Cond Res 32(1): 248-254, 2018-The purpose of this study was to determine the relationship between ground reaction force (GRF) variables to jump height, jump time, and the reactive strength index (RSI). Twenty-six, Division-I, male, soccer players performed 3 maximum effort countermovement jumps (CMJs) on a dual-force platform system that measured 3-dimensional kinetic data. The trial producing peak jump height was used for analysis. Vertical GRF (Fz) variables were divided into unloading, eccentric, amortization, and concentric phases and correlated with jump height, RSI (RSI = jump height/jump time), and jump time (from start to takeoff). Significant correlations were observed between jump height and RSI, concentric kinetic energy, peak power, concentric work, and concentric displacement. Significant correlations were observed between RSI and jump time, peak power, unload Fz, eccentric work, eccentric rate of force development (RFD), amortization Fz, amortization time, second Fz peak, average concentric Fz, and concentric displacement. Significant correlations were observed between jump time and unload Fz, eccentric work, eccentric RFD, amortization Fz, amortization time, average concentric Fz, and concentric work. In conclusion, jump height correlated with variables derived from the concentric phase only (work, power, and displacement), whereas Fz variables from the unloading, eccentric, amortization, and concentric phases correlated highly with RSI and jump time. These observations demonstrate the importance of countermovement Fz characteristics for time-sensitive CMJ performance measures. Researchers and practitioners should include RSI and jump time with jump height to improve their assessment of jump performance.
Adaptive resummation of Markovian quantum dynamics
International Nuclear Information System (INIS)
Lucas, Felix
2014-01-01
In this thesis we derive a highly convergent, nonperturbative expansion of Markovian open quantum dynamics. It is based on a splitting of the incoherent dynamics into periods of continuous evolution and abrupt jumps and attains its favorable convergence properties from an adaptive resummation of this so-called jump expansion. By means of the long-standing problems of spatial particle detection and Landau-Zener tunneling in the presence of dephasing, we show that this adaptive resummation technique facilitates new highly accurate analytic approximations of Markovian open systems. The open Landau-Zener model leads us to propose an efficient and robust incoherent control technique for the isomerization reaction of the visual pigment protein rhodopsin. Besides leading to approximate analytic descriptions of Markovian open quantum dynamics, the adaptive resummation of the jump expansion implies an efficient numerical simulation method. We spell out the corresponding numerical algorithm by means of Monte Carlo integration of the relevant terms in the jump expansion and demonstrate it in a set of paradigmatic open quantum systems.
Accuracy of Jump-Mat Systems for Measuring Jump Height.
Pueo, Basilio; Lipinska, Patrycja; Jiménez-Olmedo, José M; Zmijewski, Piotr; Hopkins, Will G
2017-08-01
Vertical-jump tests are commonly used to evaluate lower-limb power of athletes and nonathletes. Several types of equipment are available for this purpose. To compare the error of measurement of 2 jump-mat systems (Chronojump-Boscosystem and Globus Ergo Tester) with that of a motion-capture system as a criterion and to determine the modifying effect of foot length on jump height. Thirty-one young adult men alternated 4 countermovement jumps with 4 squat jumps. Mean jump height and standard deviations representing technical error of measurement arising from each device and variability arising from the subjects themselves were estimated with a novel mixed model and evaluated via standardization and magnitude-based inference. The jump-mat systems produced nearly identical measures of jump height (differences in means and in technical errors of measurement ≤1 mm). Countermovement and squat-jump height were both 13.6 cm higher with motion capture (90% confidence limits ±0.3 cm), but this very large difference was reduced to small unclear differences when adjusted to a foot length of zero. Variability in countermovement and squat-jump height arising from the subjects was small (1.1 and 1.5 cm, respectively, 90% confidence limits ±0.3 cm); technical error of motion capture was similar in magnitude (1.7 and 1.6 cm, ±0.3 and ±0.4 cm), and that of the jump mats was similar or smaller (1.2 and 0.3 cm, ±0.5 and ±0.9 cm). The jump-mat systems provide trustworthy measurements for monitoring changes in jump height. Foot length can explain the substantially higher jump height observed with motion capture.
Stephenson, Mitchell L; Hinshaw, Taylour J; Wadley, Haley A; Zhu, Qin; Wilson, Margaret A; Byra, Mark; Dai, Boyi
2018-03-01
A variety of the available time to react (ATR) has been utilised to study knee biomechanics during reactive jump-landing tasks. The purpose was to quantify knee kinematics and kinetics during a jump-land-jump task of three possible directions as the ATR was reduced. Thirty-four recreational athletes performed 45 trials of a jump-land-jump task, during which the direction of the second jump (lateral, medial or vertical) was indicated before they initiated the first jump, the instant they initiated the first jump, 300 ms before landing, 150 ms before landing or at the instant of landing. Knee joint angles and moments close to the instant of landing were significantly different when the ATR was equal to or more than 300 ms before landing, but became similar when the ATR was 150 ms or 0 ms before landing. As the ATR was decreased, knee moments decreased for the medial jump direction, but increased for the lateral jump direction. When the ATR is shorter than an individual's reaction time, the movement pattern cannot be pre-planned before landing. Knee biomechanics are dependent on the timing of the signal and the subsequent jump direction. Precise control of timing and screening athletes with low ATR are suggested.
Data-Driven Jump Detection Thresholds for Application in Jump Regressions
Directory of Open Access Journals (Sweden)
Robert Davies
2018-03-01
Full Text Available This paper develops a method to select the threshold in threshold-based jump detection methods. The method is motivated by an analysis of threshold-based jump detection methods in the context of jump-diffusion models. We show that over the range of sampling frequencies a researcher is most likely to encounter that the usual in-fill asymptotics provide a poor guide for selecting the jump threshold. Because of this we develop a sample-based method. Our method estimates the number of jumps over a grid of thresholds and selects the optimal threshold at what we term the ‘take-off’ point in the estimated number of jumps. We show that this method consistently estimates the jumps and their indices as the sampling interval goes to zero. In several Monte Carlo studies we evaluate the performance of our method based on its ability to accurately locate jumps and its ability to distinguish between true jumps and large diffusive moves. In one of these Monte Carlo studies we evaluate the performance of our method in a jump regression context. Finally, we apply our method in two empirical studies. In one we estimate the number of jumps and report the jump threshold our method selects for three commonly used market indices. In the other empirical application we perform a series of jump regressions using our method to select the jump threshold.
Mobile Jump Assessment (mJump): A Descriptive and Inferential Study.
Mateos-Angulo, Alvaro; Galán-Mercant, Alejandro; Cuesta-Vargas, Antonio
2015-08-26
Vertical jump tests are used in athletics and rehabilitation to measure physical performance in people of different age ranges and fitness. Jumping ability can be analyzed through different variables, and the most commonly used are fly time and jump height. They can be obtained by a variety of measuring devices, but most are limited to laboratory use only. The current generation of smartphones contains inertial sensors that are able to record kinematic variables for human motion analysis, since they are tools for easy access and portability for clinical use. The aim of this study was to describe and analyze the kinematics characteristics using the inertial sensor incorporated in the iPhone 4S, the lower limbs strength through a manual dynamometer, and the jump variables obtained with a contact mat in the squat jump and countermovement jump tests (fly time and jump height) from a cohort of healthy people. A cross sectional study was conducted on a population of healthy young adults. Twenty-seven participants performed three trials (n=81 jumps) of squat jump and countermovement jump tests. Acceleration variables were measured through a smartphone's inertial sensor. Additionally, jump variables from a contact mat and lower limbs dynamometry were collected. In the present study, the kinematic variables derived from acceleration through the inertial sensor of a smartphone iPhone 4S, dynamometry of lower limbs with a handheld dynamometer, and the height and flight time with a contact mat have been described in vertical jump tests from a cohort of young healthy subjects. The development of the execution has been described, examined and identified in a squat jump test and countermovement jump test under acceleration variables that were obtained with the smartphone. The built-in iPhone 4S inertial sensor is able to measure acceleration variables while performing vertical jump tests for the squat jump and countermovement jump in healthy young adults. The acceleration
Quantum information processing
National Research Council Canada - National Science Library
Leuchs, Gerd; Beth, Thomas
2003-01-01
... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.5 SimulationofHamiltonians... References... 1 1 1 3 5 8 10 2 Quantum Information Processing and Error Correction with Jump Codes (G. Alber, M. Mussinger...
Xie, Xufen; Yan, Jiawei; Liang, Jinghong; Li, Jijun; Zhang, Meng; Mao, Bingwei
2013-10-01
We present quantum conductance measurements of germanium by means of an electrochemical scanning tunneling microscope (STM) break junction based on a jump-to-contact mechanism. Germanium nanowires between a platinum/iridium tip and different substrates were constructed to measure the quantum conductance. By applying appropriate potentials to the substrate and the tip, the process of heterogeneous contact and homogeneous breakage was realized. Typical conductance traces exhibit steps at 0.025 and 0.05 G0. The conductance histogram indicates that the conductance of germanium nanowires is located between 0.02 and 0.15 G0 in the low-conductance region and is free from the influence of substrate materials. However, the distribution of conductance plateaus is too discrete to display distinct peaks in the conductance histogram of the high-conductance region. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Non-reversible evolution of quantum chaotic system. Kinetic description
International Nuclear Information System (INIS)
Chotorlishvili, L.; Skrinnikov, V.
2008-01-01
It is well known that the appearance of non-reversibility in classical chaotic systems is connected with a local instability of phase trajectories relatively to a small change of initial conditions and parameters of the system. Classical chaotic systems reveal an exponential sensitivity to these changes. This leads to an exponential growth of initial error with time, and as the result after the statistical averaging over this error, the dynamics of the system becomes non-reversible. In spite of this, the question about the origin of non-reversibility in quantum case remains actual. The point is that the classical notion of instability of phase trajectories loses its sense during quantum consideration. The current work is dedicated to the clarification of the origin of non-reversibility in quantum chaotic systems. For this purpose we study a non-stationary dynamics of the chaotic quantum system. By analogy with classical chaos, we consider an influence of a small unavoidable error of the parameter of the system on the non-reversibility of the dynamics. It is shown in the Letter that due to the peculiarity of chaotic quantum systems, the statistical averaging over the small unavoidable error leads to the non-reversible transition from the pure state into the mixed one. The second part of the Letter is dedicated to the kinematic description of the chaotic quantum-mechanical system. Using the formalism of superoperators, a muster kinematic equation for chaotic quantum system was obtained from Liouville equation under a strict mathematical consideration
Chaos, entropy, and life-time in classical and quantum systems
International Nuclear Information System (INIS)
Seyed Majid Saberi Fathi
2007-07-01
In this thesis, we first study Lorentz gas as a billiard ball with elastic collision with the obstacles and a system of hard spheres in 2-dimensions. We study a numerical simulation of the dynamical system and we investigate the entropy increasing in non-equilibrium with time under the effect of collisions and its relation to positive Lyapunov exponents. Then, we study a decay model in a quantum system called Friedrichs model. We consider coupling of the kaons and environment with continuous energies. Then, we show that this model is well adapted to describe oscillation, regeneration, decay and CP violation of a kaonic system. In addition, we apply in the Friedrichs model, the time super-operator formalism that predicts the resonance, i.e. the survival probability of the instable states. (author)
DEFF Research Database (Denmark)
Ravn, Susanne; Voigt, M; Simonsen, Erik Bruun
1999-01-01
. 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....
Scaling of quantum Fisher information close to the quantum phase transition in the XY spin chain
Energy Technology Data Exchange (ETDEWEB)
Ye, En-Jia, E-mail: yeenjia@jiangnan.edu.cn [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Hu, Zheng-Da [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Wu, Wei [Zhejiang Institute of Modern Physics and Physics Department, Zhejiang University, Hangzhou 310027 (China)
2016-12-01
The quantum phase transition of an XY spin chain is investigated by employing the quantum Fisher information encoded in the ground state. It is shown that the quantum Fisher information is an effective tool for characterizing the quantum criticality. The quantum Fisher information, its first and second derivatives versus the transverse field display the phenomena of sudden transition, sudden jump and divergence, respectively. Besides, the analysis of finite size scaling for the second derivative of quantum Fisher information is performed.
Physical description of decay processes
International Nuclear Information System (INIS)
Henin, F.; Mayne, F.
1981-01-01
A dynamical formulation of quasi-particles corresponding to complex poles of Green's functions has been provided in the frame of 'Liapounov' transformations in a superoperator formalism. In this formalism, two different superorperators are associated with the hamiltonian, on the one hand an energy superoperator H, and on the other hand, an evolution superoperator L. In the case of systems with continuous spectrum it is possible to diagonalize the transform of H, the diagonal elements being the energies found by the Green's functions methods. This can be achieved without diagonalizing at the same time, the transform of L: the inverse lifetimes and the collision processes are obtained in this way. We show here on the Friedrichs model, that we can specify uniquely such a transformation in agreement with our previous 'new quantum rules for dissipative systems'. This method can be generalized to more complex systems. (orig.)
Drop Jumping as a Training Method for Jumping Ability
Bobbert, Maarten F.
1990-01-01
Vertical jumping ability is of importance for good performance in sports such as basketball and volleyball. Coaches are in need of exercises that consume only little time and still help to improve their players’ jumping ability, without involving a high risk of injury. Drop jumping is assumed to
Jump locations of jump-diffusion processes with state-dependent rates
International Nuclear Information System (INIS)
Miles, Christopher E; Keener, James P
2017-01-01
We propose a general framework for studying statistics of jump-diffusion systems driven by both Brownian noise (diffusion) and a jump process with state-dependent intensity. Of particular natural interest in many physical systems are the jump locations: the system evaluated at the jump times. As an example, this could be the voltage at which a neuron fires, or the so-called ‘threshold voltage’. However, the state-dependence of the jump rate provides direct coupling between the diffusion and jump components, making it difficult to disentangle the two to study individually. In this work, we provide an iterative map formulation of the sequence of distributions of jump locations. The distributions computed by this map can be used to elucidate other interesting quantities about the process, including statistics of the interjump times. Ultimately, the limit of the map reveals that knowledge of the stationary distribution of the full process is sufficient to recover (but not necessarily equal to) the distribution of jump locations. We propose two biophysical examples to illustrate the use of this framework to provide insight about a system. We find that a sharp threshold voltage emerges robustly in a simple stochastic integrate-and-fire neuronal model. The interplay between the two sources of noise is also investigated in a stepping model of molecular motor in intracellular transport pulling a diffusive cargo. (paper)
A Correction Equation for Jump Height Measured Using the Just Jump System.
McMahon, John J; Jones, Paul A; Comfort, Paul
2016-05-01
To determine the concurrent validity and reliability of the popular Just Jump system (JJS) for determining jump height and, if necessary, provide a correction equation for future reference. Eighteen male college athletes performed 3 bilateral countermovement jumps (CMJs) on 2 JJSs (alternative method) that were placed on top of a force platform (criterion method). Two JJSs were used to establish consistency between systems. Jump height was calculated from flight time obtained from the JJS and force platform. Intraclass correlation coefficients (ICCs) demonstrated excellent within-session reliability of the CMJ height measurement derived from both the JJS (ICC = .96, P jump height (0.46 ± 0.09 m vs 0.33 ± 0.08 m) than the force platform (P jump height = (0.8747 × alternative jump height) - 0.0666. The JJS provides a reliable but overestimated measure of jump height. It is suggested, therefore, that practitioners who use the JJS as part of future work apply the correction equation presented in this study to resultant jump-height values.
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 degrees......, while idiosyncratic jumps are stock-specific. Despite the fact that each of the stocks has a of about unity with respect to the index, common jumps are virtually never detected in the individual stocks. This is truly puzzling, as an index can jump only if one or more of its components jump. To resolve...... this puzzle, we propose a new test for cojumps. Using this new test we find strong evidence for many modest-sized common jumps that simply pass through the standard jump detection statistic, while they appear highly significant in the cross section based on the new cojump identification scheme. Our results...
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.
2016-01-01
Abstract Pauli, CA, Keller, M, Ammann, F, Hübner, K, Lindorfer, J, Taylor, WR, and Lorenzetti, S. Kinematics and kinetics of squats, drop jumps and imitation jumps of ski jumpers. J Strength Cond Res 30(3): 643–652, 2016—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. PMID:26418370
Why is countermovement jump height greater than squat jump height?
Bobbert, Maarten F.; Gerritsen, Karin G M; Litjens, Maria C A; Van Soest, Arthur J.
1996-01-01
In the literature, it is well established that subjects are able to jump higher in a countermovement jump (CMJ) than in a squat jump (SJ). The purpose of this study was to estimate the relative contribution of the time available for force development and the storage and reutilization of elastic
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.
Tracking an open quantum system using a finite state machine: Stability analysis
International Nuclear Information System (INIS)
Karasik, R. I.; Wiseman, H. M.
2011-01-01
A finite-dimensional Markovian open quantum system will undergo quantum jumps between pure states, if we can monitor the bath to which it is coupled with sufficient precision. In general these jumps, plus the between-jump evolution, create a trajectory which passes through infinitely many different pure states, even for ergodic systems. However, as shown recently by us [Phys. Rev. Lett. 106, 020406 (2011)], it is possible to construct adaptive monitorings which restrict the system to jumping between a finite number of states. That is, it is possible to track the system using a finite state machine as the apparatus. In this paper we consider the question of the stability of these monitoring schemes. Restricting to cyclic jumps for a qubit, we give a strong analytical argument that these schemes are always stable and supporting analytical and numerical evidence for the example of resonance fluorescence. This example also enables us to explore a range of behaviors in the evolution of individual trajectories, for several different monitoring schemes.
International Nuclear Information System (INIS)
Calarco, T.; Datta, A.; Fedichev, P.; Zoller, P.; Pazy, E.
2003-01-01
We present an all-optical implementation of quantum computation using semiconductor quantum dots. Quantum memory is represented by the spin of an excess electron stored in each dot. Two-qubit gates are realized by switching on trion-trion interactions between different dots. State selectivity is achieved via conditional laser excitation exploiting Pauli exclusion principle. Read out is performed via a quantum-jump technique. We analyze the effect on our scheme's performance of the main imperfections present in real quantum dots: exciton decay, hole mixing, and phonon decoherence. We introduce an adiabatic gate procedure that allows one to circumvent these effects and evaluate quantitatively its fidelity
Psychophysiological response in parachute jumps, the effect of experience and type of jump.
Clemente-Suárez, Vicente Javier; Robles-Pérez, José Juan; Fernández-Lucas, Jesús
2017-10-01
We aimed to analyse the effect of experience and type of parachute jump on the psychophysiological responses of jumpers. We analysed blood oxygen saturation, heart rate, blood glucose, lactate and creatinkinase, leg strength, isometric hand strength, cortical arousal, specific fine motor skills, self-confidence and cognition, and somatic and state anxiety, before and after four different parachute jumps: a sport parachute jump, a manual tactical parachute jump, tandem pilots, and tandem passengers. Independently of the parachute jump, the psychophysiological responses of experienced paratroopers were not affected by the jumps, except for an increase in anaerobic metabolism. Novice parachute jumpers presented a higher psychophysiological stress response than the experienced jumpers, together with a large anticipatory anxiety response before the jump; however, this decreased after the jump, although the high physiological activation was maintained. This information could be used by civil and military paratroopers' instructors to improve their training programmes. Copyright © 2017 Elsevier Inc. All rights reserved.
The effect of assisted jumping on vertical jump height in high-performance volleyball players.
Sheppard, Jeremy M; Dingley, Andrew A; Janssen, Ina; Spratford, Wayne; Chapman, Dale W; Newton, Robert U
2011-01-01
Assisted jumping may be useful in training higher concentric movement speed in jumping, thereby potentially increasing the jumping abilities of athletes. The purpose of this study was to evaluate the effects of assisted jump training on counter-movement vertical jump (CMVJ) and spike jump (SPJ) ability in a group of elite male volleyball players. Seven junior national team volleyball players (18.0±1.0 yrs, 200.4±6.7 cm, and 84.0±7.2 kg) participated in this within-subjects cross-over counter-balanced training study. Assisted training involved 3 sessions per week of CMVJ training with 10 kg of assistance, applied through use of a bungee system, whilst normal jump training involved equated volume of unassisted counter-movement vertical jumps. Training periods were 5 weeks duration, with a 3-week wash-out separating them. Prior to and at the conclusion of each training period jump testing for CMVJ and SPJ height was conducted. Assisted jump training resulted in gains of 2.7±0.7 cm (pSports Medicine Australia. All rights reserved.
Visser, Albert
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
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
Energy Technology Data Exchange (ETDEWEB)
Fischer, Ernst Peter
2015-07-01
It's madness, yet there is method. The physical phenomenon of the quantum jump has already brought some well-known physicists at the edge of dispair. Then nothing seems to be such illogical, undetermined, and unpredictable as the behaviour of the atoms that ultimatively form our world. The renowned historian of sciences Ernst Peter Fischer tells the fascinating story of quantum physics by means of poignant portraits of selected researchers like Max Planck, Werner Heisenberg, Richard P. Feynman, and ''Mr. Beam'' Anton Zeilinger. A great story of science a bout the smallest particles of the nature.
The reliability of vertical jump tests between the Vertec and My Jump phone application.
Yingling, Vanessa R; Castro, Dimitri A; Duong, Justin T; Malpartida, Fiorella J; Usher, Justin R; O, Jenny
2018-01-01
The vertical jump is used to estimate sports performance capabilities and physical fitness in children, elderly, non-athletic and injured individuals. Different jump techniques and measurement tools are available to assess vertical jump height and peak power; however, their use is limited by access to laboratory settings, excessive cost and/or time constraints thus making these tools oftentimes unsuitable for field assessment. A popular field test uses the Vertec and the Sargent vertical jump with countermovement; however, new low cost, easy to use tools are becoming available, including the My Jump iOS mobile application (app). The purpose of this study was to assess the reliability of the My Jump relative to values obtained by the Vertec for the Sargent stand and reach vertical jump (VJ) test. One hundred and thirty-five healthy participants aged 18-39 years (94 males, 41 females) completed three maximal Sargent VJ with countermovement that were simultaneously measured using the Vertec and the My Jump . Jump heights were quantified for each jump and peak power was calculated using the Sayers equation. Four separate ICC estimates and their 95% confidence intervals were used to assess reliability. Two analyses (with jump height and calculated peak power as the dependent variables, respectively) were based on a single rater, consistency, two-way mixed-effects model, while two others (with jump height and calculated peak power as the dependent variables, respectively) were based on a single rater, absolute agreement, two-way mixed-effects model. Moderate to excellent reliability relative to the degree of consistency between the Vertec and My Jump values was found for jump height (ICC = 0.813; 95% CI [0.747-0.863]) and calculated peak power (ICC = 0.926; 95% CI [0.897-0.947]). However, poor to good reliability relative to absolute agreement for VJ height (ICC = 0.665; 95% CI [0.050-0.859]) and poor to excellent reliability relative to absolute agreement for peak power
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.
Measurements of K shell absorption jump factors and jump ratios using EDXRF technique
Kacal, Mustafa Recep; Han, İbrahim; Akman, Ferdi
2015-04-01
In the present work, the K-shell absorption jump factors and jump ratios for 30 elements between Ti ( Z = 22) and Er ( Z = 68) were measured by energy dispersive X-ray fluorescence (EDXRF) technique. The jump factors and jump ratios for these elements were determined by measuring the K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to- Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using an Am-241 radioactive point source and a Si (Li) detector in direct excitation and transmission experimental geometry. The results for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature.
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.
Strength Determinants of Jump Height in the Jump Throw Movement in Women Handball Players.
McGhie, David; Østerås, Sindre; Ettema, Gertjan; Paulsen, Gøran; Sandbakk, Øyvind
2018-06-08
McGhie, D, Østerås, S, Ettema, G, Paulsen, G, and Sandbakk, Ø. Strength determinants of jump height in the jump throw movement in women handball players. J Strength Cond Res XX(X): 000-000, 2018-The purpose of the study was to improve the understanding of the strength demands of a handball-specific jump through examining the associations between jump height in a jump throw jump (JTJ) and measures of lower-body maximum strength and impulse in handball players. For comparison, whether the associations between jump height and strength differed between the JTJ and the customarily used countermovement jump (CMJ) was also examined. Twenty women handball players from a Norwegian top division club participated in the study. Jump height was measured in the JTJ and in unilateral and bilateral CMJ. Lower-body strength (maximum isometric force, one-repetition maximum [1RM], impulse at ∼60% and ∼35% 1RM) was measured in seated leg press. The associations between jump height and strength were assessed with correlation analyses and t-tests of dependent r's were performed to determine if correlations differed between jump tests. Only impulse at ∼35% 1RM correlated significantly with JTJ height (p jump height and strength were significantly weaker in the JTJ than in both CMJ tests for all strength measures (p = 0.001-0.044) except one. Maximum strength and impulse at ∼60% 1RM did not seem to sufficiently capture the capabilities associated with JTJ height, highlighting the importance of employing tests targeting performance-relevant neuromuscular characteristics when assessing jump-related strength in handball players. Further, CMJ height seemed to represent a wider range of strength capabilities and care should be taken when using it as a proxy for handball-specific movements.
Davis, Caitlin M; Reddish, Michael J; Dyer, R Brian
2017-05-05
Time-resolved temperature-jump (T-jump) coupled with fluorescence and infrared (IR) spectroscopy is a powerful technique for monitoring protein dynamics. Although IR spectroscopy of the polypeptide amide I mode is more technically challenging, it offers complementary information because it directly probes changes in the protein backbone, whereas, fluorescence spectroscopy is sensitive to the environment of specific side chains. With the advent of widely tunable quantum cascade lasers (QCL) it is possible to efficiently probe multiple IR frequencies with high sensitivity and reproducibility. Here we describe a dual time-resolved T-jump fluorescence and IR spectrometer and its application to study protein folding dynamics. A Q-switched Ho:YAG laser provides the T-jump source for both time-resolved IR and fluorescence spectroscopy, which are probed by a QCL and Ti:Sapphire laser, respectively. The Ho:YAG laser simultaneously pumps the time-resolved IR and fluorescence spectrometers. The instrument has high sensitivity, with an IR absorbance detection limit of jump induced difference spectrum from 50ns to 0.5ms. This study demonstrates the power of the dual time-resolved T-jump fluorescence and IR spectroscopy to resolve complex folding mechanisms by complementary IR absorbance and fluorescence measurements of protein dynamics. Copyright © 2017 Elsevier B.V. All rights reserved.
Coordination in vertical jumping
Bobbert, Maarten F.; van Ingen Schenau, Gerrit Jan
1988-01-01
The present study was designed to investigate for vertical jumping the relationships between muscle actions, movement pattern and jumping achievement. Ten skilled jumpers performed jumps with preparatory countermovement. Ground reaction forces and cinematographic data were recorded. In addition,
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...... the weak assumption of regular variation in the jump tails, along with in-fill asymptotic arguments for uniquely identifying the "large" jumps from the data. The estimation allows for very general dynamic dependencies in the jump tails, and does not restrict the continuous part of the process...... and the temporal variation in the stochastic volatility. On implementing the new estimation procedure with actual high-frequency data for the S&P 500 aggregate market portfolio, we find strong evidence for richer and more complex dynamic dependencies in the jump tails than hitherto entertained in the literature....
Quantum algorithms and quantum maps - implementation and error correction
International Nuclear Information System (INIS)
Alber, G.; Shepelyansky, D.
2005-01-01
Full text: We investigate the dynamics of the quantum tent map under the influence of errors and explore the possibilities of quantum error correcting methods for the purpose of stabilizing this quantum algorithm. It is known that static but uncontrollable inter-qubit couplings between the qubits of a quantum information processor lead to a rapid Gaussian decay of the fidelity of the quantum state. We present a new error correcting method which slows down this fidelity decay to a linear-in-time exponential one. One of its advantages is that it does not require redundancy so that all physical qubits involved can be used for logical purposes. We also study the influence of decoherence due to spontaneous decay processes which can be corrected by quantum jump-codes. It is demonstrated how universal encoding can be performed in these code spaces. For this purpose we discuss a new entanglement gate which can be used for lowest level encoding in concatenated error-correcting architectures. (author)
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.
International Nuclear Information System (INIS)
Taylor, P R; Baker, R E; Yates, C A
2015-01-01
In this paper we explore lattice-based position-jump models of diffusion, and the implications of introducing non-local jumping; particles can jump to a range of nearby boxes rather than only to their nearest neighbours. We begin by deriving conditions for equivalence with traditional local jumping models in the continuum limit. We then generalize a previously postulated implementation of the Robin boundary condition for a non-local process of arbitrary maximum jump length, and present a novel implementation of flux boundary conditions, again generalized for a non-local process of arbitrary maximum jump length. In both these cases we validate our results using stochastic simulation. We then proceed to consider two variations on the basic diffusion model: a hybrid local/non-local scheme suitable for models involving sharp concentration gradients, and the implementation of biased jumping. In all cases we show that non-local jumping can deliver substantial time savings for stochastic simulations. (paper)
Quantum trajectory phase transitions in the micromaser.
Garrahan, Juan P; Armour, Andrew D; Lesanovsky, Igor
2011-08-01
We study the dynamics of the single-atom maser, or micromaser, by means of the recently introduced method of thermodynamics of quantum jump trajectories. We find that the dynamics of the micromaser displays multiple space-time phase transitions, i.e., phase transitions in ensembles of quantum jump trajectories. This rich dynamical phase structure becomes apparent when trajectories are classified by dynamical observables that quantify dynamical activity, such as the number of atoms that have changed state while traversing the cavity. The space-time transitions can be either first order or continuous, and are controlled not just by standard parameters of the micromaser but also by nonequilibrium "counting" fields. We discuss how the dynamical phase behavior relates to the better known stationary-state properties of the micromaser.
Influence of Knee-to-Feet Jump Training on Vertical Jump and Hang Clean Performance.
Stark, Laura; Pickett, Karla; Bird, Michael; King, Adam C
2016-11-01
Stark, L, Pickett, K, Bird, M, and King, AC. Influence of knee-to-feet jump training on vertical jump and hang clean performance. J Strength Cond Res 30(11): 3084-3089, 2016-From a motor learning perspective, the practice/training environment can result in positive, negative, or neutral transfer to the testing conditions. The purpose of this study was to examine the training effect of a novel movement (knee-to-feet [K2F] jumps) and whether a 6-week training program induced a positive transfer effect to other power-related movements (vertical jump and hang clean [HC]). Twenty-six intercollegiate athletes from power-emphasized sports were paired and counter-balanced into a control (i.e., maintained their respective sport-specific lifting regimen) or an experimental group (i.e., completed a 6-week progressive training program of K2F jumps in addition to respective lifting regimen). A pre- and posttest design was used to investigate the effect of training on K2F jump height and transfer effect to vertical jump height (VJH) and 2-repetition maximum (RM) HC performance. A significant increase in K2F jump height was found for the experimental group. Vertical jump height significantly increased from pre- to posttest but no group or interaction (group × time) effect was found, and there were nonsignificant differences for HC. Posttest data showed significant correlations between all pairs of the selected exercises with the highest correlation between K2F jump height and VJ H (R = 0.40) followed by VJH and 2RM HC (R = 0.38) and 2RM HC and K2F jump height (R = 0.23). The results suggest that K2F jump training induced the desired learning effect but was specific to the movement in that no effect of transfer occurred to the other power-related movements. This finding is value for strength and condition professionals who design training programs to enhance athletic performance.
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.
Miura, Ken; Yamamoto, Masayoshi; Tamaki, Hiroyuki; Zushi, Koji
2010-01-01
This study was conducted to obtain useful information for developing training techniques for the running 1-legged vertical jump in basketball (lay-up shot jump). The ability to perform the lay-up shot jump and various basic jumps was measured by testing 19 male basketball players. The basic jumps consisted of the 1-legged repeated rebound jump, the 2-legged repeated rebound jump, and the countermovement jump. Jumping height, contact time, and jumping index (jumping height/contact time) were measured and calculated using a contact mat/computer system that recorded the contact and air times. The jumping index indicates power. No significant correlation existed between the jumping height and contact time of the lay-up shot jump, the 2 components of the lay-up shot jump index. As a result, jumping height and contact time were found to be mutually independent abilities. The relationships in contact time between the lay-up shot jump to the 1-legged repeated rebound jump and the 2-legged repeated rebound jump were correlated on the same significance levels (p jumping height existed between the 1-legged repeated rebound jump and the lay-up shot jump (p jumping height between the lay-up shot jump and both the 2-legged repeated rebound jump and countermovement jump. The lay-up shot index correlated more strongly to the 1-legged repeated rebound jump index (p jump index (p jump is effective in improving both contact time and jumping height in the lay-up shot jump.
The Effects of Aquatic Plyometric Training on Repeated Jumps, Drop Jumps and Muscle Damage.
Jurado-Lavanant, A; Alvero-Cruz, J R; Pareja-Blanco, F; Melero-Romero, C; Rodríguez-Rosell, D; Fernandez-Garcia, J C
2015-09-22
The purpose of this study was to compare the effects of land- vs. aquatic based plyometric training programs on the drop jump, repeated jump performance and muscle damage. Sixty-five male students were randomly assigned to one of 3 groups: aquatic plyometric training group (APT), plyometric training group (PT) and control group (CG). Both experimental groups trained twice a week for 10 weeks performing the same number of sets and total jumps. The following variables were measured prior to, halfway through and after the training programs: creatine kinase (CK) concentration, maximal height during a drop jump from the height of 30 (DJ30) and 50 cm (DJ50), and mean height during a repeated vertical jump test (RJ). The training program resulted in a significant increase (Pplyometric training, PT produced greater gains on reactive jumps performance than APT. © Georg Thieme Verlag KG Stuttgart · New York.
Rantalainen, T; Hesketh, K D; Rodda, C; Duckham, R L
2018-06-16
Jump tests assess lower body power production capacity, and can be used to evaluate athletic ability and development during growth. Wearable inertial measurement units (IMU) seem to offer a feasible alternative to laboratory-based equipment for jump height assessments. Concurrent validity of these devices for jump height assessments has only been established in adults. Therefore, the purpose of this study was to evaluate the concurrent validity of IMU-based jump height estimate compared to contact mat-based jump height estimate in adolescents. Ninety-five adolescents (10-13 years-of-age; girls N=41, height = 154 (SD 9) cm, weight = 44 (11) kg; boys N=54, height=156 (10) cm, weight = 46 (13) kg) completed three counter-movement jumps for maximal jump height on a contact mat. Inertial recordings (accelerations, rotations) were concurrently recorded with a hip-worn IMU (sampling at 256 Hz). Jump height was evaluated based on flight time. The mean IMU-derived jump height was 27.1 (SD 3.8) cm, and the corresponding mean jump-mat-derived value was 21.5 (3.4) cm. While a significant 26% mean difference was observed between the methods (5.5 [95% limits of agreement 2.2 to 8.9] cm, p = 0.006), the correspondence between methods was excellent (ICC = 0.89). The difference between methods was weakly positively associated with jump height (r = 0.28, P = 0.007). Take-off velocity derived jump height was also explored but produced only fair congruence. In conclusion, IMU-derived jump height exhibited excellent congruence to contact mat-based jump height and therefore presents a feasible alternative for jump height assessments in adolescents. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.
Fitzgerald, John S; Johnson, LuAnn; Tomkinson, Grant; Stein, Jesse; Roemmich, James N
2018-05-01
Mechanography during the vertical jump may enhance screening and determining mechanistic causes underlying physical performance changes. Utility of jump mechanography for evaluation is limited by scant test-retest reliability data on force-time variables. This study examined the test-retest reliability of eight jump execution variables assessed from mechanography. Thirty-two women (mean±SD: age 20.8 ± 1.3 yr) and 16 men (age 22.1 ± 1.9 yr) attended a familiarization session and two testing sessions, all one week apart. Participants performed two variations of the squat jump with squat depth self-selected and controlled using a goniometer to 80º knee flexion. Test-retest reliability was quantified as the systematic error (using effect size between jumps), random error (using coefficients of variation), and test-retest correlations (using intra-class correlation coefficients). Overall, jump execution variables demonstrated acceptable reliability, evidenced by small systematic errors (mean±95%CI: 0.2 ± 0.07), moderate random errors (mean±95%CI: 17.8 ± 3.7%), and very strong test-retest correlations (range: 0.73-0.97). Differences in random errors between controlled and self-selected protocols were negligible (mean±95%CI: 1.3 ± 2.3%). Jump execution variables demonstrated acceptable reliability, with no meaningful differences between the controlled and self-selected jump protocols. To simplify testing, a self-selected jump protocol can be used to assess force-time variables with negligible impact on measurement error.
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
Clissold, Tracey L; Winwood, Paul W; Cronin, John B; De Souza, Mary Jane
2018-04-01
Jumps have been investigated as a stimulus for bone development; however, effects of instruction, jump type, and jump-landing techniques need investigation. This study sought to identify whether ground reaction forces (GRFs) for bilateral vertical jumps (countermovement jumps and drop jumps) with reactive jump-landings (ie, jumping immediately after initial jump-landing), with instruction and with instruction withdrawn, achieve magnitudes and rates of strain previously shown to improve bone mass among premenopausal women. Twenty-one women (Mean ± SD: 43.3 ± 5.9 y; 69.4 ± 9.6 kg; 167 ± 5.5 cm; 27.5 ± 8.7% body fat) performed a testing session 'with instruction' followed by a testing session performed 1 week later with 'instruction withdrawn.' The magnitudes (4.59 to 5.49 body weight [BW]) and rates of strain (263 to 359 BW·s -1 ) for the jump-landings, performed on an AMTI force plate, exceeded previously determined thresholds (>3 BWs and >43 BW·s -1 ). Interestingly, significantly larger peak resultant forces, (↑10%; P = .002) and peak rates of force development (↑20%; P jump-landing (postreactive jump). Small increases (ES = 0.22-0.42) in all landing forces were observed in the second jump-landing with 'instruction withdrawn.' These jumps represent a unique training stimulus for premenopausal women and achieve osteogenic thresholds thought prerequisite for bone growth.
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.
From the atomic nucleus to the cosmos. How the strange laws of the quantum world form our reality
International Nuclear Information System (INIS)
Beckers, Mike
2016-01-01
The following topics are dealt with: The reality of nature, Hamlet in quantum world, the ene of the local realism, quantum jumps, a new quantum theory, string theory for solids, atomic nuclei between liquid and crystal, simulated quantum worlds, space-time entanglement, Einstein in the quantum test, quantum cryptography, quantum computers as code breaker. (HSI)
Variation in free jumping technique within and among horses with little experience in show jumping
Santamaria, S.; Bobbert, M.F.; Back, W.; Barneveld, A.; van Weeren, P.R.
2004-01-01
Objective - To quantify variation in the jumping technique within and among young horses with little jumping experience, establish relationships between kinetic and kinematic variables, and identify a limited set of variables characteristic for detecting differences in jumping performance among
Validity of a Jump Mat for assessing Countermovement Jump Performance in Elite Rugby Players.
Dobbin, Nick; Hunwicks, Richard; Highton, Jamie; Twist, Craig
2017-02-01
This study determined the validity of the Just Jump System ® (JJS) for measuring flight time, jump height and peak power output (PPO) in elite rugby league players. 37 elite rugby league players performed 6 countermovement jumps (CMJ; 3 with and 3 without arms) on a jump mat and force platform. A sub-sample (n=28) was used to cross-validate the equations for flight time, jump height and PPO. The JJS systematically overestimated flight time and jump height compared to the force platform (Pjump height ( with R 2 =0.945; without R 2 =0.987). Our equations revealed no systematic difference between corrected and force platform scores and an improved the agreement for flight time (Ratio limits of agreement: with 1.00 vs. 1.36; without 1.00 vs. 1.16) and jump height ( with 1.01 vs. 1.34; without 1.01 vs. 1.15), meaning that our equations can be used to correct JJS scores for elite rugby players. While our equation improved the estimation of PPO ( with 1.02; without 1.01) compared to existing equations (Harman: 1.20; Sayers: 1.04), this only accounted for 64 and 69% of PPO. © Georg Thieme Verlag KG Stuttgart · New York.
Indian Academy of Sciences (India)
SARS – virus jumps species. Coronavirus reshuffles genes; Rotteir et al, Rotterdam showed the virus to jump from cats to mouse cells after single gene mutation ? Human disease due to virus jumping from wild or domestic animals; Present favourite animal - the cat; - edible or domestic.
A quantum extended Kalman filter
International Nuclear Information System (INIS)
Emzir, Muhammad F; Woolley, Matthew J; Petersen, Ian R
2017-01-01
In quantum physics, a stochastic master equation (SME) estimates the state (density operator) of a quantum system in the Schrödinger picture based on a record of measurements made on the system. In the Heisenberg picture, the SME is a quantum filter. For a linear quantum system subject to linear measurements and Gaussian noise, the dynamics may be described by quantum stochastic differential equations (QSDEs), also known as quantum Langevin equations, and the quantum filter reduces to a so-called quantum Kalman filter. In this article, we introduce a quantum extended Kalman filter (quantum EKF), which applies a commutative approximation and a time-varying linearization to systems of nonlinear QSDEs. We will show that there are conditions under which a filter similar to a classical EKF can be implemented for quantum systems. The boundedness of estimation errors and the filtering problem with ‘state-dependent’ covariances for process and measurement noises are also discussed. We demonstrate the effectiveness of the quantum EKF by applying it to systems that involve multiple modes, nonlinear Hamiltonians, and simultaneous jump-diffusive measurements. (paper)
A quantum extended Kalman filter
Emzir, Muhammad F.; Woolley, Matthew J.; Petersen, Ian R.
2017-06-01
In quantum physics, a stochastic master equation (SME) estimates the state (density operator) of a quantum system in the Schrödinger picture based on a record of measurements made on the system. In the Heisenberg picture, the SME is a quantum filter. For a linear quantum system subject to linear measurements and Gaussian noise, the dynamics may be described by quantum stochastic differential equations (QSDEs), also known as quantum Langevin equations, and the quantum filter reduces to a so-called quantum Kalman filter. In this article, we introduce a quantum extended Kalman filter (quantum EKF), which applies a commutative approximation and a time-varying linearization to systems of nonlinear QSDEs. We will show that there are conditions under which a filter similar to a classical EKF can be implemented for quantum systems. The boundedness of estimation errors and the filtering problem with ‘state-dependent’ covariances for process and measurement noises are also discussed. We demonstrate the effectiveness of the quantum EKF by applying it to systems that involve multiple modes, nonlinear Hamiltonians, and simultaneous jump-diffusive measurements.
Increase in Jumping Height Associated with Maximal Effort Vertical Depth Jumps.
Bedi, John F.; And Others
1987-01-01
In order to assess if there existed a statistically significant increase in jumping performance when dropping from different heights, 32 males, aged 19 to 26, performed a series of maximal effort vertical jumps after dropping from eight heights onto a force plate. Results are analyzed. (Author/MT)
Quantum walks and search algorithms
Portugal, Renato
2013-01-01
This book addresses an interesting area of quantum computation called quantum walks, which play an important role in building quantum algorithms, in particular search algorithms. Quantum walks are the quantum analogue of classical random walks. It is known that quantum computers have great power for searching unsorted databases. This power extends to many kinds of searches, particularly to the problem of finding a specific location in a spatial layout, which can be modeled by a graph. The goal is to find a specific node knowing that the particle uses the edges to jump from one node to the next. This book is self-contained with main topics that include: Grover's algorithm, describing its geometrical interpretation and evolution by means of the spectral decomposition of the evolution operater Analytical solutions of quantum walks on important graphs like line, cycles, two-dimensional lattices, and hypercubes using Fourier transforms Quantum walks on generic graphs, describing methods to calculate the limiting d...
Energy Technology Data Exchange (ETDEWEB)
Seyed Majid Saberi Fathi
2007-07-15
In this thesis, we first study Lorentz gas as a billiard ball with elastic collision with the obstacles and a system of hard spheres in 2-dimensions. We study a numerical simulation of the dynamical system and we investigate the entropy increasing in non-equilibrium with time under the effect of collisions and its relation to positive Lyapunov exponents. Then, we study a decay model in a quantum system called Friedrichs model. We consider coupling of the kaons and environment with continuous energies. Then, we show that this model is well adapted to describe oscillation, regeneration, decay and CP violation of a kaonic system. In addition, we apply in the Friedrichs model, the time super-operator formalism that predicts the resonance, i.e. the survival probability of the instable states. (author)
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.
International Nuclear Information System (INIS)
Labuntsov, D.A.; Avdeev, A.A.
1981-01-01
Concept of boiling-up jump representing a zone of intense volume boiling-up separating overtaking flow of overheated metastable liquid from an area of equilibrium flow located below along the flow is introduced. It is shown that boiling-up jump is a shock wave of rarefaction. It is concluded that entropy increment occurs on the jump. Characteristics of adiabatic shock wave curve of boiling- up in ''pressure-specific volume'' coordinates have been found and its form has been investigated. Stability of boiling-up jump has been analyzed as well. On the basis of approach developed analysis is carried out on the shock adiobatic curve of condensation. Concept of boiling-up jump may be applied to the analysis of boiling-up processes when flowing liquid through packings during emergency pressure drop etc [ru
International Nuclear Information System (INIS)
Polat, Recep; İçelli, Orhan; Yalçın, Zeynel; Pesen, Erhan; Orak, Salim
2013-01-01
Highlights: ► Mass attenuation coefficients, jump factor and jump ratio for lanthanide elements are obtained. ► The method used in this experiment is combined both transmission and scattering geometry. ► Secondary gamma rays energy is 59.5 keV. ► Experimental values of jump factor and jump ratio for K shell are new. ► The experimental values are in good agreement with those calculated theoretically. - Abstract: 59.5 keV gamma rays scattered by an aluminum foil have been used as a radiation source to measure the absorption jump factor and jump ratios for absorbers Ce, Pr, Nd, Sm, Eu and Tb. The theoretical and experimental values are compared with the corresponding ones in the literature
BPS Jumping Loci are Automorphic
Kachru, Shamit; Tripathy, Arnav
2018-06-01
We show that BPS jumping loci-loci in the moduli space of string compactifications where the number of BPS states jumps in an upper semi-continuous manner—naturally appear as Fourier coefficients of (vector space-valued) automorphic forms. For the case of T 2 compactification, the jumping loci are governed by a modular form studied by Hirzebruch and Zagier, while the jumping loci in K3 compactification appear in a story developed by Oda and Kudla-Millson in arithmetic geometry. We also comment on some curious related automorphy in the physics of black hole attractors and flux vacua.
Energy Technology Data Exchange (ETDEWEB)
Hui, Ning-Ju [Department of Applied Physics, Xi' an University of Technology, Xi' an 710054 (China); Xu, Yang-Yang; Wang, Jicheng; Zhang, Yixin [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China); Hu, Zheng-Da, E-mail: huyuanda1112@jiangnan.edu.cn [Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122 (China)
2017-04-01
We investigate the properties of geometric quantum coherence in the XY spin-1/2 chain with staggered Dzyaloshinsky-Moriya interaction via the quantum renormalization-group approach. It is shown that the geometric quantum coherence and its coherence susceptibility are effective to detect the quantum phase transition. In the thermodynamic limit, the geometric quantum coherence exhibits a sudden jump. The coherence susceptibilities versus the anisotropy parameter and the Dzyaloshinsky-Moriya interaction are infinite and vanishing, respectively, illustrating the distinct roles of the anisotropy parameter and the Dzyaloshinsky-Moriya interaction in quantum phase transition. Moreover, we also explore the finite-size scaling behaviors of the coherence susceptibilities. For a finite-size chain, the coherence susceptibility versus the phase-transition parameter is always maximal at the critical point, indicating the dramatic quantum fluctuation. Besides, we show that the correlation length can be revealed by the scaling exponent for the coherence susceptibility versus the Dzyaloshinsky-Moriya interaction.
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…
Mayato, R; Egusquiza, I
2002-01-01
The treatment of time in quantum mechanics is still an important and challenging open question in the foundation of the theory. This book describes the problems, and the attempts and achievements in defining, formalizing and measuring different time quantities in quantum theory, such as the parametric (clock) time, tunneling times, decay times, dwell times, delay times, arrival times or jump times. This multiauthored book, written as an introductory guide for the non-initiated as well as a useful source of information for the expert, covers many of the open questions. A brief historical overview is to be found in the introduction. It is followed by 12 chapters devoted to conceptual and theoretical investigations as well as experimental issues in quantum-mechanical time measurements. This unique monograph should attract physicists as well as philosophers of science working in the foundations of quantum physics.
Ski jumping boots limit effective take-off in ski jumping.
Virmavirta, M; Komi, P V
2001-12-01
In this study, we measured the vertical and horizontal take-off forces, plantar pressures and activation patterns of four muscles (vastus lateralis, gluteus maximus, tibialis anterior, gastrocnemius) in 10 ski jumpers in simulated laboratory conditions when wearing either training shoes or ski jumping boots. We found significant differences in vertical (P boots condition resulted in a smaller displacement in the final position of the following joint angles: ankle angle (P knee angle (P boots condition, significantly more pressure was recorded under the heel (P knee and hip extensors when wearing jumping boots. We conclude that the stiffness of the structure of the jumping boots may result in a forward shift of pressure, thus limiting the effective vertical force. To avoid this pressure shift, the pattern of movement of simulated take-offs should be carefully controlled, particularly when wearing training shoes.
Duchesne, Alexis; Bohr, Tomas; Andersen, Anders
2017-11-01
The hydraulic jump, i.e., the sharp transition between a supercritical and a subcritical free-surface flow, has been extensively studied in the past centuries. However, ever since Leonardo da Vinci asked it for the first time, an important question has been left unanswered: How does a hydraulic jump form? We present an experimental and theoretical study of the formation of stationary hydraulic jumps in centimeter wide channels. Two starting situations are considered: The channel is, respectively, empty or filled with liquid, the liquid level being fixed by the wetting properties and the boundary conditions. We then change the flow-rate abruptly from zero to a constant value. In an empty channel, we observe the formation of a stationary hydraulic jump in a two-stage process: First, the channel fills by the advancing liquid front, which undergoes a transition from supercritical to subcritical at some position in the channel. Later the influence of the downstream boundary conditions makes the jump move slowly upstream to its final position. In the pre-filled channel, the hydraulic jump forms at the injector edge and then moves downstream to its final position.
Directory of Open Access Journals (Sweden)
Mandic Radivoj
2016-09-01
Full Text Available The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles.
Mandic, Radivoj; Knezevic, Olivera M; Mirkov, Dragan M; Jaric, Slobodan
2016-09-01
The aim of the present study was to explore the control strategy of maximum countermovement jumps regarding the preferred countermovement depth preceding the concentric jump phase. Elite basketball players and physically active non-athletes were tested on the jumps performed with and without an arm swing, while the countermovement depth was varied within the interval of almost 30 cm around its preferred value. The results consistently revealed 5.1-11.2 cm smaller countermovement depth than the optimum one, but the same difference was more prominent in non-athletes. In addition, although the same differences revealed a marked effect on the recorded force and power output, they reduced jump height for only 0.1-1.2 cm. Therefore, the studied control strategy may not be based solely on the countermovement depth that maximizes jump height. In addition, the comparison of the two groups does not support the concept of a dual-task strategy based on the trade-off between maximizing jump height and minimizing the jumping quickness that should be more prominent in the athletes that routinely need to jump quickly. Further research could explore whether the observed phenomenon is based on other optimization principles, such as the minimization of effort and energy expenditure. Nevertheless, future routine testing procedures should take into account that the control strategy of maximum countermovement jumps is not fully based on maximizing the jump height, while the countermovement depth markedly confound the relationship between the jump height and the assessed force and power output of leg muscles.
Jump conditions in transonic equilibria
International Nuclear Information System (INIS)
Guazzotto, L.; Betti, R.; Jardin, S. C.
2013-01-01
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-β, 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-β, 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 β, while they agree with the results obtained with the old implementation of FLOW in lower-β equilibria.
Connecting two jumplike unravelings for non-Markovian open quantum systems
Energy Technology Data Exchange (ETDEWEB)
Luoma, Kimmo; Suominen, Kalle-Antti; Piilo, Jyrki [Turku Centre for Quantum Physics, Department of Physics and Astronomy, University of Turku, FI-20014 Turun Yliopisto (Finland)
2011-09-15
The development and use of Monte Carlo algorithms plays a visible role in the study of non-Markovian quantum dynamics due to the provided insight and powerful numerical methods for solving the system dynamics. In the Markovian case, the connections between the various types of methods are fairly well understood while, for the non-Markovian case, there has so far been only a few studies. We focus here on two jumplike unravelings of non-Markovian dynamics: the non-Markovian quantum jump (NMQJ) method and the property state method by Gambetta, Askerud, and Wiseman (GAW). The results for simple quantum optical systems illustrate the connections between the realizations of the two methods and also highlight how the probability currents between the system and environment, or between the property states of the total system, are associated with the decay rates of time-local master equations and, consequently, with the jump rates of the NMQJ method.
Connecting two jumplike unravelings for non-Markovian open quantum systems
International Nuclear Information System (INIS)
Luoma, Kimmo; Suominen, Kalle-Antti; Piilo, Jyrki
2011-01-01
The development and use of Monte Carlo algorithms plays a visible role in the study of non-Markovian quantum dynamics due to the provided insight and powerful numerical methods for solving the system dynamics. In the Markovian case, the connections between the various types of methods are fairly well understood while, for the non-Markovian case, there has so far been only a few studies. We focus here on two jumplike unravelings of non-Markovian dynamics: the non-Markovian quantum jump (NMQJ) method and the property state method by Gambetta, Askerud, and Wiseman (GAW). The results for simple quantum optical systems illustrate the connections between the realizations of the two methods and also highlight how the probability currents between the system and environment, or between the property states of the total system, are associated with the decay rates of time-local master equations and, consequently, with the jump rates of the NMQJ method.
Structure of the Balmer jump. The isolated hydrogen atom
Calvo, F.; Belluzzi, L.; Steiner, O.
2018-06-01
Context. The spectrum of the hydrogen atom was explained by Bohr more than one century ago. We revisit here some of the aspects of the underlying quantum structure, with a modern formalism, focusing on the limit of the Balmer series. Aims: We investigate the behaviour of the absorption coefficient of the isolated hydrogen atom in the neighbourhood of the Balmer limit. Methods: We analytically computed the total cross-section arising from bound-bound and bound-free transitions in the isolated hydrogen atom at the Balmer limit, and established a simplified semi-analytical model for the surroundings of that limit. We worked within the framework of the formalism of Landi Degl'Innocenti & Landolfi (2004, Astrophys. Space Sci. Lib., 307), which permits an almost straight-forward generalization of our results to other atoms and molecules, and which is perfectly suitable for including polarization phenomena in the problem. Results: We analytically show that there is no discontinuity at the Balmer limit, even though the concept of a "Balmer jump" is still meaningful. Furthermore, we give a possible definition of the location of the Balmer jump, and we check that this location is dependent on the broadening mechanisms. At the Balmer limit, we compute the cross-section in a fully analytical way. Conclusions: The Balmer jump is produced by a rapid drop of the total Balmer cross-section, yet this variation is smooth and continuous when both bound-bound and bound-free processes are taken into account, and its shape and location is dependent on the broadening mechanisms.
International Nuclear Information System (INIS)
Kaçal, M.R.
2014-01-01
Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring L 3 -subshell absorption jump ratios, r L 3 and jump factors, J L 3 for high Z elements. Jump factors and jump ratios for these elements have been determined by measuring L 3 subshell fluorescence parameters such as L 3 subshell X-ray production cross section σ L 3 , L 3 subshell fluorescence yield, ω L 3 , total L 3 subshell and higher subshells photoionization cross section σ L T . Measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation experimental geometry. Measured values for jump factors and jump ratios have been compared with theoretically calculated and other experimental values. - Highlights: • This paper regards L 3 subshell absorption jump ratios and jump factors using the EDXRF method. • These parameters were measured using a new method. • This method is more useful than other methods which require much effort. • Results are in good agreement with theoretical and experimental values
Experimental study of the hydraulic jump in a hydraulic jump in a ...
African Journals Online (AJOL)
The hydraulic jump in a sloped rectangular channel is theoretically and experimentally examined. The study aims to determine the effect of the channel's slope on the sequent depth ratio of the jump. A theoretical relation is proposed for the inflow Froude number as function of the sequent depth ratio and the channel slope.
Kim, Ho-Young; Amauger, Juliette; Jeong, Han-Bi; Lee, Duck-Gyu; Yang, Eunjin; Jablonski, Piotr G.
2017-10-01
Some species of semiaquatic arthropods including water striders and springtails can jump from the water surface to avoid sudden dangers like predator attacks. It was reported recently that the jump of medium-sized water striders is a result of surface-tension-dominated interaction of thin cylindrical legs and water, with the leg movement speed nearly optimized to achieve the maximum takeoff velocity. Here we describe the mathematical theories to analyze this exquisite feat of nature by combining the review of existing models for floating and jumping and the introduction of the hitherto neglected capillary forces at the cylinder tips. The theoretically predicted dependence of body height on time is shown to match the observations of the jumps of the water striders and springtails regardless of the length of locomotory appendages. The theoretical framework can be used to understand the design principle of small jumping animals living on water and to develop biomimetic locomotion technology in semiaquatic environments.
Force generation and temperature-jump and length-jump tension transients in muscle fibers.
Davis, J S; Rodgers, M E
1995-01-01
Muscle tension rises with increasing temperature. The kinetics that govern the tension rise of maximally Ca(2+)-activated, skinned rabbit psoas fibers over a temperature range of 0-30 degrees C was characterized in laser temperature-jump experiments. The kinetic response is simple and can be readily interpreted in terms of a basic three-step mechanism of contraction, which includes a temperature-sensitive rapid preequilibrium(a) linked to a temperature-insensitive rate-limiting step and followed by a temperature-sensitive tension-generating step. These data and mechanism are compared and contrasted with the more complex length-jump Huxley-Simmons phases in which all states that generate tension or bear tension are perturbed. The rate of the Huxley-Simmons phase 4 is temperature sensitive at low temperatures but plateaus at high temperatures, indicating a change in rate-limiting step from a temperature-sensitive (phase 4a) to a temperature-insensitive reaction (phase 4b); the latter appears to correlate with the slow, temperature-insensitive temperature-jump relaxation. Phase 3 is absent in the temperature-jump, which excludes it from tension generation. We confirm that de novo tension generation occurs as an order-disorder transition during phase 2slow and the equivalent, temperature-sensitive temperature-jump relaxation. PMID:7612845
Energy Technology Data Exchange (ETDEWEB)
Li, Deyong; Li, Yunliang; Li, Hao; Weng, Yuxiang, E-mail: yxweng@iphy.ac.cn [Key Laboratory of Soft Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Wu, Xianyou [Anhui Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031 (China); Yu, Qingxu [School of Physics and Optoelectronic Technology, Dalian University of Technology, No. 2, Linggong Road, Dalian 116023 (China)
2015-05-15
Knowledge of dynamical structure of protein is an important clue to understand its biological function in vivo. Temperature-jump (T-jump) time-resolved transient mid-IR absorbance spectroscopy is a powerful tool in elucidating the protein dynamical structures and the folding/unfolding kinetics of proteins in solution. A home-built setup of T-jump time-resolved transient mid-IR absorbance spectroscopy with high sensitivity is developed, which is composed of a Q-switched Cr, Tm, Ho:YAG laser with an output wavelength at 2.09 μm as the T-jump heating source, and a continuous working CO laser tunable from 1580 to 1980 cm{sup −1} as the IR probe. The results demonstrate that this system has a sensitivity of 1 × 10{sup −4} ΔOD for a single wavelength detection, and 2 × 10{sup −4} ΔOD for spectral detection in amide I′ region, as well as a temporal resolution of 20 ns. Moreover, the data quality coming from the CO laser is comparable to the one using the commercial quantum cascade laser.
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.
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.
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...
International Nuclear Information System (INIS)
Kragh, Helge
2000-01-01
Physicists often complain that the phrase q uantum leap'' is used erroneously, if harmlessly, by people to describe a large jump or change. Yet this month the physics community is celebrating the 100th anniversary of what must count as the beginning of the biggest quantum leap in the history of science, whichever way you define the phrase. On 14 December 1900 Max Planck presented a paper on the radiation emitted by a black body at a meeting of the German Physical Society in Berlin. This event is generally taken to mark the start of the quantum century, though few people realized it at the time - not even Planck himself. (U.K.)
Jump spillover between oil prices and exchange rates
Li, Xiao-Ping; Zhou, Chun-Yang; Wu, Chong-Feng
2017-11-01
In this paper, we investigate the jump spillover effects between oil prices and exchange rates. To identify the latent historical jumps for exchange rates and oil prices, we use a Bayesian MCMC approach to estimate the stochastic volatility model with correlated jumps in both returns and volatilities for each. We examine the simultaneous jump intensities and the conditional jump spillover probabilities between oil prices and exchange rates, finding strong evidence of jump spillover effects. Further analysis shows that the jump spillovers are mainly due to exogenous events such as financial crises and geopolitical events. Thus, the findings have important implications for financial risk management.
Nonequilibrium dynamics of polariton entanglement in a cluster of coupled traps
Energy Technology Data Exchange (ETDEWEB)
Quiroga, L [Departamento de Fisica, Universidad de Los Andes, A.A.4976, Bogota D.C. (Colombia); Tejedor, C, E-mail: lquiroga@uniandes.edu.c [Departamento de Fisica Teorica de la Materia Condensada, Universidad Autonoma de Madrid, Cantoblanco, E-28049, Madrid (Spain)
2009-05-01
We study in detail the generation and relaxation of quantum coherences (entanglement) in a system of coupled polariton traps. By exploiting a Lie algebraic based super-operator technique we provide an analytical exact solution for the Markovian dissipative dynamics (Master equation) of such system which is valid for arbitrary cluster size, polariton-polariton interaction strength, temperature and initial state. Based on the exact solution of the Master equation at T = OK, we discuss how dissipation affects the quantum entanglement dynamics of coupled polariton systems.
Characteristics of Air Entrainment in Hydraulic Jump
Albarkani, M. S. S.; Tan, L. W.; Al-Gheethi, A.
2018-04-01
The characteristics of hydraulic jump, especially the air entrainment within jump is still not properly understood. Therefore, the current work aimed to determine the size and number of air entrainment formed in hydraulic jump at three different Froude numbers and to obtain the relationship between Froude number with the size and number of air entrainment in hydraulic jump. Experiments of hydraulic jump were conducted in a 10 m long and 0.3 m wide Armfield S6MKII glass-sided tilting flume. Hydraulic jumps were produced by flow under sluice gate with varying Froude number. The air entrainment of the hydraulic jump was captured with a Canon Power Shot SX40 HS digital camera in video format at 24 frames per second. Three discharges have been considered, i.e. 0.010 m3/s, 0.011 m3/s, and 0.013 m3/s. For hydraulic jump formed in each discharge, 32 frames were selected for the purpose of analysing the size and number of air entrainment in hydraulic jump. The results revealed that that there is a tendency to have greater range in sizes of air bubbles as Fr1 increases. Experiments with Fr1 = 7.547. 7.707, and 7.924 shown that the number of air bubbles increases exponentially with Fr1 at a relationship of N = 1.3814 e 0.9795Fr1.
Haynes, Tom; Bishop, Chris; Antrobus, Mark; Brazier, Jon
2018-03-27
This is the first study to independently assess the concurrent validity and reliability of the My Jump 2 app for measuring drop jump performance. It is also the first to evaluate the app's ability to measure the reactive strength index (RSI). Fourteen male sport science students (age: 29.5 ± 9.9 years) performed three drop jumps from 20 cm and 40 cm (totalling 84 jumps), assessed via a force platform and the My Jump 2 app. Reported metrics included reactive strength index, jump height, ground contact time, and mean power. Measurements from both devices were compared using the intraclass correlation coefficient (ICC), Pearson product moment correlation coefficient (r), Cronbach's alpha (α), coefficient of variation (CV) and BlandAltman plots. Near perfect agreement was seen between devices at 20 cm for RSI (ICC = 0.95) and contact time (ICC = 0.99) and at 40 cm for RSI (ICC = 0.98), jump height (ICC = 0.96) and contact time (ICC = 0.92); with very strong agreement seen at 20 cm for jump height (ICC = 0.80). In comparison with the force plate the app showed good validity for RSI (20 cm: r = 0.94; 40 cm; r = 0.97), jump height (20 cm: r = 0.80; 40 cm; r = 0.96) and contact time (20 cm = 0.96; 40 cm; r = 0.98). The results of the present study show that the My Jump 2 app is a valid and reliable tool for assessing drop jump performance.
Predicting vertical jump height from bar velocity.
García-Ramos, Amador; Štirn, Igor; Padial, Paulino; Argüelles-Cienfuegos, Javier; De la Fuente, Blanca; Strojnik, Vojko; Feriche, Belén
2015-06-01
The objective of the study was to assess the use of maximum (Vmax) and final propulsive phase (FPV) bar velocity to predict jump height in the weighted jump squat. FPV was defined as the velocity reached just before bar acceleration was lower than gravity (-9.81 m·s(-2)). Vertical jump height was calculated from the take-off velocity (Vtake-off) provided by a force platform. Thirty swimmers belonging to the National Slovenian swimming team performed a jump squat incremental loading test, lifting 25%, 50%, 75% and 100% of body weight in a Smith machine. Jump performance was simultaneously monitored using an AMTI portable force platform and a linear velocity transducer attached to the barbell. Simple linear regression was used to estimate jump height from the Vmax and FPV recorded by the linear velocity transducer. Vmax (y = 16.577x - 16.384) was able to explain 93% of jump height variance with a standard error of the estimate of 1.47 cm. FPV (y = 12.828x - 6.504) was able to explain 91% of jump height variance with a standard error of the estimate of 1.66 cm. Despite that both variables resulted to be good predictors, heteroscedasticity in the differences between FPV and Vtake-off was observed (r(2) = 0.307), while the differences between Vmax and Vtake-off were homogenously distributed (r(2) = 0.071). These results suggest that Vmax is a valid tool for estimating vertical jump height in a loaded jump squat test performed in a Smith machine. Key pointsVertical jump height in the loaded jump squat can be estimated with acceptable precision from the maximum bar velocity recorded by a linear velocity transducer.The relationship between the point at which bar acceleration is less than -9.81 m·s(-2) and the real take-off is affected by the velocity of movement.Mean propulsive velocity recorded by a linear velocity transducer does not appear to be optimal to monitor ballistic exercise performance.
International Nuclear Information System (INIS)
Kim, Seyoung
2017-01-01
In this study, we investigated how a jumping strategy changes with an increase in the vertical jump height for a resultant ground reaction force (GRF) vector. We expected that the resultant force vector between two sequential motion phases (i.e., countermovement and push-off) of the counter movement jump would significantly change with the vertical jump height to take advantage of the resulting supportive force (i.e., an initial push-off force larger than the body weight) through the counter movement phase. Nine healthy young subjects were instructed to jump straight up to five different height levels ranging from 191 cm to 221 cm, and the kinematic and kinetic data were obtained in regular trials. The results showed that a lower center of mass position and larger resultant force vector were clearly observed in a higher jump, implying that the counter movement strategy changed with the vertical jump height to prepare for sufficient joint deviation and obtain a force advantage for larger push-off work.
Energy Technology Data Exchange (ETDEWEB)
Kim, Seyoung [Korea Institute of Machinery and Materials(KIMM), Daejeon (Korea, Republic of)
2017-04-15
In this study, we investigated how a jumping strategy changes with an increase in the vertical jump height for a resultant ground reaction force (GRF) vector. We expected that the resultant force vector between two sequential motion phases (i.e., countermovement and push-off) of the counter movement jump would significantly change with the vertical jump height to take advantage of the resulting supportive force (i.e., an initial push-off force larger than the body weight) through the counter movement phase. Nine healthy young subjects were instructed to jump straight up to five different height levels ranging from 191 cm to 221 cm, and the kinematic and kinetic data were obtained in regular trials. The results showed that a lower center of mass position and larger resultant force vector were clearly observed in a higher jump, implying that the counter movement strategy changed with the vertical jump height to prepare for sufficient joint deviation and obtain a force advantage for larger push-off work.
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...
Determinant Factors of the Squat Jump in Sprinting and Jumping Athletes
Directory of Open Access Journals (Sweden)
González-Badillo Juan José
2017-08-01
Full Text Available The aim of this study was to assess the relationship between strength variables and maximum velocity (Vmax in the squat jump (SJ in sprinting and jumping athletes. Thirty-two sprinting and jumping athletes of national level (25.4 ± 4.5 years; 79.4 ± 6.9 kg and 180.4 ± 6.0 cm participated in the study. Vmax in the SJ showed significant relationships with peak force 1 (PF1 (r = 0.82, p ≤ 0.001, peak force 2 (PF2 (r = 0.68, p ≤ 0.001, PF2 by controlling for PF1 (r = 0.30, non-significant, the maximum rate of force development at peak force 1 (RFDmax1 (r = 0.62, p ≤ 0.001, mean RFD 1 (RFDmean1 (r = 0.48, p ≤ 0.01, mean RFD 2 (RFDmean2 (r = 0.70, p ≤ 0.001, force at RFDmax1 (r = 0.36, p ≤ 0.05, force at RFDmax2 (r = 0.83, p ≤ 0.001 and force at RFDmax2 by controlling for PF1 (r = 0.40, p ≤ 0.05. However, Vmax in the SJ was associated negatively with the ratio PF2/PF1 (r = -0.54, p ≤ 0.01, time at peak force 2 (Tp2 (r = -0.64, p ≤ 0.001 and maximum rate of force development at peak force 2 (RFDmax2 (r = -0.71, p ≤ 0.001. These findings indicate that the peak force achieved at the beginning of the movement (PF1 is the main predictor of performance in jumping, although the RFDmax values and the ratio PF2/PF1 are also variables to be taken into account when analyzing the determinant factors of vertical jumping.
Hidden Statistics Approach to Quantum Simulations
Zak, Michail
2010-01-01
transitional potential is to provide a jump from a deterministic state to a random state with prescribed probability density. This jump is triggered by blowup instability due to violation of Lipschitz condition generated by the quantum potential. As a result, the dynamics attains quantum properties on a classical scale. The model can be implemented physically as an analog VLSI-based (very-large-scale integration-based) computer, or numerically on a digital computer. This work opens a way of developing fundamentally new algorithms for quantum simulations of exponentially complex problems that expand NASA capabilities in conducting space activities. It has been illustrated that the complexity of simulations of particle interaction can be reduced from an exponential one to a polynomial one.
Approaches to open quantum systems: Decoherence, localisation and all that
International Nuclear Information System (INIS)
Yu Ting
1998-01-01
This thesis is mainly concerned with issues in quantum open systems and the foundations of quantum theory. Chapter I introduces the aim, background and main results which take place in the following chapters. Chapters II and III are used to study and compare the decoherent histories approach, the environment-induced decoherence and the localisation properties of the solutions to the stochastic Schrodinger equation in quantum jump simulation and quantum state diffusion approaches, for a quantum two-level system model. We show, in particular, that there is a close connection between the decoherent histories and the quantum jump simulation, complementing a connection with the quantum state diffusion approach noted earlier by Diosi, Gisin, Halliwell and Percival. In the case of the decoherent histories analysis, the degree of approximate decoherence is discussed in detail. As by-product, by using the von Neumann entropy, we also discuss the predictability and its relation to the upper bounds of degree of decoherence. In Chapter IV, we give an alternative and elementary derivation of the Hu-Paz-Ghang master equation for quantum Brownian motion in a general environment, which involves tracing the evolution equation for the Wigner function. We also discuss the master equation in some special cases. This master equation provides a very useful tool to study the decoherence of a quantum system due to the interaction with its environment. In Chapter V, a derivation of the parameter-based uncertainty relation between position and momentum is given. This uncertainty relation can be regarded as an exact counterpart of the time-energy uncertainty relation. The final chapter is a rather brief summary of the thesis. (author)
Drop jumping. II. The influence of dropping height on the biomechanics of drop jumping
Bobbert, M F; Huijing, P A; van Ingen Schenau, G J
In the literature, athletes preparing for explosive activities are recommended to include drop jumping in their training programs. For the execution of drop jumps, different techniques and different dropping heights can be used. This study was designed to investigate for the performance of bounce
A Jump Diffusion Model for Volatility and Duration
DEFF Research Database (Denmark)
Wei, Wei; Pelletier, Denis
by the market microstructure theory. Traditional measures of volatility do not utilize durations. I adopt a jump diffusion process to model the persistence of intraday volatility and conditional duration, and their interdependence. The jump component is disentangled from the continuous part of the price......, volatility and conditional duration process. I develop a MCMC algorithm for the inference of irregularly spaced multivariate process with jumps. The algorithm provides smoothed estimates of the latent variables such as spot volatility, jump times and jump sizes. I apply this model to IBM data and I find...... meaningful relationship between volatility and conditional duration. Also, jumps play an important role in the total variation, but the jump variation is smaller than traditional measures that use returns sampled at lower frequency....
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
Oranchuk, Dustin J; Robinson, Tracey L; Switaj, Zachary J; Drinkwater, Eric J
2017-04-15
Weightlifting movements have high skill demands and require expert coaching. Loaded jumps have a comparably lower skill demand, but may be similarly effective for improving explosive performance. The purpose of this study was to compare vertical jump performance, isometric force, and rate of force development (RFD) following a ten-week intervention employing the hang high-pull (hang-pull) or trap-bar jump squat (jump-squat). Eighteen NCAA Division II swimmers (8 males, 10 females) with at least one year of resistance training experience volunteered to participate. Testing included the squat jump (SJ), countermovement jump (CMJ) and the isometric mid-thigh pull (IMTP). Vertical ground reaction forces were analyzed to obtain jump height and relative peak power. Relative peak force, peak RFD and relative force at five time bands were obtained from the IMTP. Subjects were randomly assigned to either a hang-pull (n = 9) or jump-squat (n = 9) training group and completed a ten-week, volume-equated, periodized training program. While there was a significant main effect of training for both groups, no statistically significant between-group differences were found (p ≥ 0.17) for any of the dependent variables. However, medium effect sizes in favor of the jump-squat training group were seen in SJ height (d = 0.56) and SJ peak power (d = 0.69). Loaded jumps seem equally effective as weightlifting derivatives for improving lower-body power in experienced athletes. Since loaded jumps require less skill and less coaching expertise than weightlifting, loaded jumps should be considered where coaching complex movements is difficult.
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
Quantum trajectory approach to the geometric phase: open bipartite systems
International Nuclear Information System (INIS)
Yi, X X; Liu, D P; Wang, W
2005-01-01
Through the quantum trajectory approach, we calculate the geometric phase acquired by a bipartite system subjected to decoherence. The subsystems that compose the bipartite system interact with each other and then are entangled in the evolution. The geometric phase due to the quantum jump for both the bipartite system and its subsystems is calculated and analysed. As an example, we present two coupled spin-1/2 particles to detail the calculations
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
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
Pressure Jumps during Drainage in Macroporous Soils
DEFF Research Database (Denmark)
Soto, Diego; Paradelo Pérez, Marcos; Corral, A
2018-01-01
Tensiometer readings obtained at high resolution during drainage of structured soil columns revealed pressure jumps with long range correlations and burst sequences with a hierarchical structure. The statistical properties of jumps are similar to Haines jumps described in invasion percolation...... processes at pore scale, but they are much larger in amplitude and duration. Pressure jumps can result from transient redistribution of water potential in internal regions of soil and can be triggered during drainage by capillary displacements at the scale of structural pores....
Jump Squat is More Related to Sprinting and Jumping Abilities than Olympic Push Press.
Loturco, I; Kobal, R; Maldonado, T; Piazzi, A F; Bottino, A; Kitamura, K; Abad, C C C; Pereira, L A; Nakamura, F Y
2017-07-01
The aim of this study was to test the relationships between jump squat (JS) and Olympic push press (OPP) power outputs and performance in sprint, squat jump (SJ), countermovement jump (CMJ) and change of direction (COD) speed tests in elite soccer players. 27 athletes performed a maximum power load test to determine their bar mean propulsive power (MPP) and bar mean propulsive velocity (MPV) in the JS and OPP exercises. Magnitude-based inference was used to compare the exercises. The MPV was almost certainly higher in the OPP than in the JS. The MPP relative to body mass (MPP REL) was possibly higher in the OPP. Only the JS MPP REL presented very large correlations with linear speed ( r> 0.7, for speed in 5, 10, 20 and 30 m) and vertical jumping abilities ( r> 0.8, for SJ and CMJ), and moderate correlation with COD speed ( r= 0.45). Although significant (except for COD), the associations between OPP outcomes and field-based measurements (speed, SJ and CMJ) were all moderate, ranging from 0.40 to 0.48. In a group composed of elite soccer players, the JS exercise is more associated with jumping and sprinting abilities than the OPP. Longitudinal studies are needed to confirm if these strong relationships imply superior training effects in favor of the JS exercise. © Georg Thieme Verlag KG Stuttgart · New York.
Functional methods and mappings of dissipative quantum systems
International Nuclear Information System (INIS)
Baur, H.
2006-01-01
In the first part of this work we extract the algebraic structure behind the method of the influence functional in the context of dissipative quantum mechanics. Special emphasis was put on the transition from a quantum mechanical description to a classical one, since it allows a deeper understanding of the measurement-process. This is tightly connected with the transition from a microscopic to a macroscopic world where the former one is described by the rules of quantum mechanics whereas the latter follows the rules of classical mechanics. In addition we show how the results of the influence functional method can be interpreted as a stochastical process, which in turn allows an easy comparison with the well known time development of a quantum mechanical system by use of the Schroedinger equation. In the following we examine the tight-binding approximation of models of which their hamiltionian shows discrete eigenstates in position space and where transitions between those states are suppressed so that propagation either is described by tunneling or by thermal activation. In the framework of dissipative quantum mechanics this leads to a tremendous simplification of the effective description of the system since instead of looking at the full history of all paths in the path integral description, we only have to look at all possible jump times and the possible corresponding set of weights for the jump direction, which is much easier to handle both analytically and numerically. In addition we deal with the mapping and the connection of dissipative quantum mechanical models with ones in quantum field theory and in particular models in statistical field theory. As an example we mention conformal invariance in two dimensions which always becomes relevant if a statistical system only has local interaction and is invariant under scaling. (orig.)
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......'s mixing-length theory with a mixing length that is proportional to the height of the fluid layer. Using averaged boundary-layer equations, taking into account the friction with the channel walls and the eddy viscosity, the flow both upstream and downstream of the jump can be understood. For the downstream...... subcritical flow, we assume that the critical height is attained close to the channel outlet. We use mass and momentum conservation to determine the position of the jump and obtain an estimate which is in rough agreement with our experiment. We show that the averaging method with a varying velocity profile...
Option Valuation with Observable Volatility and Jump Dynamics
DEFF Research Database (Denmark)
Christoffersen, Peter; Feunoua, 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...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...
Option Valuation with Observable Volatility and Jump Dynamics
DEFF Research Database (Denmark)
Christoffersen, Peter; Feunoua, Bruno; Jeon, Yoontae
2015-01-01
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...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...
DESIGN OF A FAST CHROMATICITY JUMP IN RHIC
International Nuclear Information System (INIS)
MONTAG, C.; KEWISCH, J.; BRUNO, D.; GANETIS, G.; LOUIE, W.
2003-01-01
During transition crossing in the .Relativistic Heavy Ion Collider (RHIC), chromaticities have to change sign. This sign change is partially accomplished by the γ t quadrupole jump; however, the resulting chromaticity jump is only Δξ x = 2.1 in the horizontal and Δξ y = 2.4 in the vertical plane. To increase the jump height, a dedicated chromaticity jump scheme has been designed, consisting of fast power supplies connected to six sextupoles per ring, which is capable of providing a chromaticity jump of Δξ = 6
Delayed feedback control in quantum transport.
Emary, Clive
2013-09-28
Feedback control in quantum transport has been predicted to give rise to several interesting effects, among them quantum state stabilization and the realization of a mesoscopic Maxwell's daemon. These results were derived under the assumption that control operations on the system are affected instantaneously after the measurement of electronic jumps through it. In this contribution, I describe how to include a delay between detection and control operation in the master equation theory of feedback-controlled quantum transport. I investigate the consequences of delay for the state stabilization and Maxwell's daemon schemes. Furthermore, I describe how delay can be used as a tool to probe coherent oscillations of electrons within a transport system and how this formalism can be used to model finite detector bandwidth.
Farr, W. M.; Mandel, I.; Stevens, D.
2015-01-01
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. PMID:26543580
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....
Quantum-corrected plasmonic field analysis using a time domain PMCHWT integral equation
Uysal, Ismail E.; Ulku, H. Arda; Bagci, Hakan
2016-01-01
When two structures are within sub-nanometer distance of each other, quantum tunneling, i.e., electrons "jumping" from one structure to another, becomes relevant. Classical electromagnetic solvers do not directly account for this additional path
Knee Muscular Control During Jump Landing in Multidirections.
Sinsurin, Komsak; Vachalathiti, Roongtiwa; Jalayondeja, Wattana; Limroongreungrat, Weerawat
2016-06-01
Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direction jump landing. Eighteen male athletes performed the jump-landing test in four directions: forward (0°), 30° diagonal, 60° diagonal, and lateral (90°). Muscles tested were vastus medialis (VM), vastus lateralis (VL), rectus femoris (RF), semitendinosus (ST), and biceps femoris (BF). A Vicon(TM) 612 workstation collected the kinematic data. An electromyography was synchronized with the Vicon(TM) Motion system to quantify dynamic muscle function. Repeated measure ANOVA was used to analyze the data. Jump-landing direction significantly influenced (P jump landing. A higher risk of knee injury might occur during lateral jump landing than forward and diagonal directions. Athletes should have more practice in jump landing in lateral direction to avoid injury. Landing technique with high knee flexion in multi-directions should be taught to jumpers for knee injury prevention.
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 (c) additional variables that influence shooting.
Kaçal, Mustafa Recep; Han, İbrahim; Akman, Ferdi
2015-01-01
Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature. Copyright © 2014 Elsevier Ltd. All rights reserved.
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.
Bell-type quantum field theories
International Nuclear Information System (INIS)
Duerr, Detlef; Goldstein, Sheldon; Tumulka, Roderich; Zanghi, Nino
2005-01-01
In his paper (1986 Beables for quantum field theory Phys. Rep. 137 49-54) John S Bell proposed how to associate particle trajectories with a lattice quantum field theory, yielding what can be regarded as a vertical bar Ψ vertical bar 2 -distributed Markov process on the appropriate configuration space. A similar process can be defined in the continuum, for more or less any regularized quantum field theory; we call such processes Bell-type quantum field theories. We describe methods for explicitly constructing these processes. These concern, in addition to the definition of the Markov processes, the efficient calculation of jump rates, how to obtain the process from the processes corresponding to the free and interaction Hamiltonian alone, and how to obtain the free process from the free Hamiltonian or, alternatively, from the one-particle process by a construction analogous to 'second quantization'. As an example, we consider the process for a second quantized Dirac field in an external electromagnetic field. (topical review)
International Nuclear Information System (INIS)
Kaçal, Mustafa Recep; Han, İbrahim; Akman, Ferdi
2015-01-01
Energy dispersive X-ray fluorescence technique (EDXRF) has been employed for measuring K-shell absorption jump factors and jump ratios for Ti, Cr, Fe, Co, Ni and Cu elements. The jump factors and jump ratios for these elements were determined by measuring K shell fluorescence parameters such as the Kα X-ray production cross-sections, K shell fluorescence yields, Kβ-to-Kα X-rays intensity ratios, total atomic absorption cross sections and mass attenuation coefficients. The measurements were performed using a Cd-109 radioactive point source and an Si(Li) detector in direct excitation and transmission experimental geometry. The measured values for jump factors and jump ratios were compared with theoretically calculated and the ones available in the literature. - Highlights: • This work regard the K shell absorption jump ratios and jump factors of Ti, Cr, Fe, Co, Ni and Cu. • This paper presents the first measurement of these parameters using the experimental K shell fluorescence parameters. • A good agreement was found between experimental and theoretical values. • The EDXRF technique was suitable, precise and reliable for the measurement of these atomic parameters
Two-electron states in double quantum dot in direct electric field
International Nuclear Information System (INIS)
Burdov, V.A.
2001-01-01
One determined analytically the wave functions of stationary states and the spectrum of two-electron system in symmetric binary quantum point. It is shown that in the normal state at the absence of external electric field the electrons due to the Coulomb blockade can not be collectively in one quantum point. In the external electric field the situation changes. When a certain critical value of field intensity is reached the probability of detection of both electrons in one quantum point by a jump increases from zero up to 1 [ru
Does trampoline or hard surface jumping influence lower extremity alignment?
Akasaka, Kiyokazu; Tamura, Akihiro; Katsuta, Aoi; Sagawa, Ayako; Otsudo, Takahiro; Okubo, Yu; Sawada, Yutaka; Hall, Toby
2017-12-01
[Purpose] To determine whether repetitive trampoline or hard surface jumping affects lower extremity alignment on jump landing. [Subjects and Methods] Twenty healthy females participated in this study. All subjects performed a drop vertical jump before and after repeated maximum effort trampoline or hard surface jumping. A three-dimensional motion analysis system and two force plates were used to record lower extremity angles, moments, and vertical ground reaction force during drop vertical jumps. [Results] Knee extensor moment after trampoline jumping was greater than that after hard surface jumping. There were no significant differences between trials in vertical ground reaction force and lower extremity joint angles following each form of exercise. Repeated jumping on a trampoline increased peak vertical ground reaction force, hip extensor, knee extensor moments, and hip adduction angle, while decreasing hip flexion angle during drop vertical jumps. In contrast, repeated jumping on a hard surface increased peak vertical ground reaction force, ankle dorsiflexion angle, and hip extensor moment during drop vertical jumps. [Conclusion] Repeated jumping on the trampoline compared to jumping on a hard surface has different effects on lower limb kinetics and kinematics. Knowledge of these effects may be useful in designing exercise programs for different clinical presentations.
Fundamental tests in Cavity Quantum Electrodynamics
CERN. Geneva
2010-01-01
At the dawn of quantum physics, Einstein and Bohr had the dream to confine a photon in a box and to use this contraption in order to illustrate the strange laws of the quantum world. Cavity Quantum Electrodynamics has now made this dream real, allowing us to actually achieve in the laboratory variants of the thought experiments of the founding fathers of quantum theory. In our work at Ecole Normale Supérieure, we use a beam of Rydberg atoms to manipulate and probe non-destructively microwave photons trapped in a very high Q superconducting cavity. We realize ideal quantum non-demolition (QND) measurements of photon numbers, observe the radiation quantum jumps due to cavity relaxation and prepare non-classical fields such as Fock and Schrödinger cat states. Combining QND photon counting with a homodyne mixing method, we reconstruct the Wigner functions of these non-classical states and, by taking snapshots of these functions at increasing times, obtain movies of the decoherence process. These experiments ope...
Vlasov, Sergei; Bessarab, Pavel F; Uzdin, Valery M; Jónsson, Hannes
2016-12-22
Transitions between states of a magnetic system can occur by jumps over an energy barrier or by quantum mechanical tunneling through the energy barrier. The rate of such transitions is an important consideration when the stability of magnetic states is assessed for example for nanoscale candidates for data storage devices. The shift in transition mechanism from jumps to tunneling as the temperature is lowered is analyzed and a general expression derived for the crossover temperature. The jump rate is evaluated using a harmonic approximation to transition state theory. First, the minimum energy path for the transition is found with the geodesic nudged elastic band method. The activation energy for the jumps is obtained from the maximum along the path, a saddle point on the energy surface, and the eigenvalues of the Hessian matrix at that point as well as at the initial state minimum used to estimate the entropic pre-exponential factor. The crossover temperature for quantum mechanical tunneling is evaluated from the second derivatives of the energy with respect to orientation of the spin vector at the saddle point. The resulting expression is applied to test problems where analytical results have previously been derived, namely uniaxial and biaxial spin systems with two-fold anisotropy. The effect of adding four-fold anisotropy on the crossover temperature is demonstrated. Calculations of the jump rate and crossover temperature for tunneling are also made for a molecular magnet containing an Mn 4 group. The results are in excellent agreement with previously reported experimental measurements on this system.
Tsoukos, Athanasios; Bogdanis, Gregory C; Terzis, Gerasimos; Veligekas, Panagiotis
2016-08-01
Tsoukos, A, Bogdanis, GC, Terzis, G, and Veligekas, P. Acute improvement of vertical jump performance after isometric squats depends on knee angle and vertical jumping ability. J Strength Cond Res 30(8): 2250-2257, 2016-This study examined the acute effects of maximum isometric squats at 2 different knee angles (90 or 140°) on countermovement jump (CMJ) performance in power athletes. Fourteen national-level male track and field power athletes completed 3 main trials (2 experimental and 1 control) in a randomized and counterbalanced order 1 week apart. Countermovement jump performance was evaluated using a force-plate before and 15 seconds, 3, 6, 9, and 12 minutes after 3 sets of 3 seconds maximum isometric contractions with 1-minute rest in between, from a squat position with knee angle set at 90 or 140°. Countermovement jump performance was improved compared with baseline only in the 140° condition by 3.8 ± 1.2% on the 12th minute of recovery (p = 0.027), whereas there was no change in CMJ height in the 90° condition. In the control condition, there was a decrease in CMJ performance over time, reaching -3.6 ± 1.2% (p = 0.049) after 12 minutes of recovery. To determine the possible effects of baseline jump performance on subsequent CMJ performance, subjects were divided into 2 groups ("high jumpers" and "low jumpers"). The baseline CMJ values of "high jumpers" and "low jumpers" differed significantly (CMJ: 45.1 ± 2.2 vs. 37.1 ± 3.9 cm, respectively, p = 0.001). Countermovement jump was increased only in the "high jumpers" group by 5.4 ± 1.4% (p = 0.001) and 7.4 ± 1.2% (p = 0.001) at the knee angles of 90 and 140°, respectively. This improvement was larger at the 140° angle (p = 0.049). Knee angle during isometric squats and vertical jumping ability are important determinants of the acute CMJ performance increase observed after a conditioning activity.
Wright, Glenn A; Pustina, Andrew A; Mikat, Richard P; Kernozek, Thomas W
2012-03-01
The purpose of this study was to determine the efficacy of estimating peak lower body power from a maximal jump squat using 3 different vertical jump prediction equations. Sixty physically active college students (30 men, 30 women) performed jump squats with a weighted bar's applied load of 20, 40, and 60% of body mass across the shoulders. Each jump squat was simultaneously monitored using a force plate and a contact mat. Peak power (PP) was calculated using vertical ground reaction force from the force plate data. Commonly used equations requiring body mass and vertical jump height to estimate PP were applied such that the system mass (mass of body + applied load) was substituted for body mass. Jump height was determined from flight time as measured with a contact mat during a maximal jump squat. Estimations of PP (PP(est)) for each load and for each prediction equation were compared with criterion PP values from a force plate (PP(FP)). The PP(est) values had high test-retest reliability and were strongly correlated to PP(FP) in both men and women at all relative loads. However, only the Harman equation accurately predicted PP(FP) at all relative loads. It can therefore be concluded that the Harman equation may be used to estimate PP of a loaded jump squat knowing the system mass and peak jump height when more precise (and expensive) measurement equipment is unavailable. Further, high reliability and correlation with criterion values suggest that serial assessment of power production across training periods could be used for relative assessment of change by either of the prediction equations used in this study.
Hydrodynamics of vertical jumping in Archer fish
Techet, Alexandra H.; Mendelson, Leah
2017-11-01
Vertical jumping for aerial prey from an aquatic environment requires both propulsive power and precise aim to succeed. Rapid acceleration to a ballistic velocity sufficient for reaching the prey height occurs before the fish leaves the water completely and experiences a thousandfold drop in force-producing ability. In addition to speed, accuracy and stability are crucial for successful feeding by jumping. This talk examines the physics of jumping using the archer fish as a model. Better known for their spitting abilities, archer fish will jump multiple body lengths out of the water for prey capture, from a stationary position just below the free surface. Modulation of oscillatory body kinematics and use of multiple fins for force production are identified as methods through which the fish can meet requirements for both acceleration and stabilization in limited space. Quantitative 3D PIV wake measurements reveal how variations in tail kinematics relate to thrust production throughout the course of a jumping maneuver and over a range of jump heights. By performing measurements in 3D, the timing, interactions, and relative contributions to thrust and lateral forces from each fin can be evaluated, elucidating the complex hydrodynamics that enable archer fish water exit.
The Role of Quantum Decoherence in FRET.
Nelson, Philip C
2018-02-16
Resonance energy transfer has become an indispensable experimental tool for single-molecule and single-cell biophysics. Its physical underpinnings, however, are subtle: it involves a discrete jump of excitation from one molecule to another, and so we regard it as a strongly quantum-mechanical process. And yet its kinetics differ from what many of us were taught about two-state quantum systems, quantum superpositions of the states do not seem to arise, and so on. Although J. R. Oppenheimer and T. Förster navigated these subtleties successfully, it remains hard to find an elementary derivation in modern language. The key step involves acknowledging quantum decoherence. Appreciating that aspect can be helpful when we attempt to extend our understanding to situations in which Förster's original analysis is not applicable. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.
A data-driven wavelet-based approach for generating jumping loads
Chen, Jun; Li, Guo; Racic, Vitomir
2018-06-01
This paper suggests an approach to generate human jumping loads using wavelet transform and a database of individual jumping force records. A total of 970 individual jumping force records of various frequencies were first collected by three experiments from 147 test subjects. For each record, every jumping pulse was extracted and decomposed into seven levels by wavelet transform. All the decomposition coefficients were stored in an information database. Probability distributions of jumping cycle period, contact ratio and energy of the jumping pulse were statistically analyzed. Inspired by the theory of DNA recombination, an approach was developed by interchanging the wavelet coefficients between different jumping pulses. To generate a jumping force time history with N pulses, wavelet coefficients were first selected randomly from the database at each level. They were then used to reconstruct N pulses by the inverse wavelet transform. Jumping cycle periods and contract ratios were then generated randomly based on their probabilistic functions. These parameters were assigned to each of the N pulses which were in turn scaled by the amplitude factors βi to account for energy relationship between successive pulses. The final jumping force time history was obtained by linking all the N cycles end to end. This simulation approach can preserve the non-stationary features of the jumping load force in time-frequency domain. Application indicates that this approach can be used to generate jumping force time history due to single people jumping and also can be extended further to stochastic jumping loads due to groups and crowds.
Jump Shrug Height and Landing Forces Across Various Loads.
Suchomel, Timothy J; Taber, Christopher B; Wright, Glenn A
2016-01-01
The purpose of this study was to examine the effect that load has on the mechanics of the jump shrug. Fifteen track and field and club/intramural athletes (age 21.7 ± 1.3 y, height 180.9 ± 6.6 cm, body mass 84.7 ± 13.2 kg, 1-repetition-maximum (1RM) hang power clean 109.1 ± 17.2 kg) performed repetitions of the jump shrug at 30%, 45%, 65%, and 80% of their 1RM hang power clean. Jump height, peak landing force, and potential energy of the system at jump-shrug apex were compared between loads using a series of 1-way repeated-measures ANOVAs. Statistical differences in jump height (P .05). The greatest magnitudes of jump height, peak landing force, and potential energy of the system at the apex of the jump shrug occurred at 30% 1RM hang power clean and decreased as the external load increased from 45% to 80% 1RM hang power clean. Relationships between peak landing force and potential energy of the system at jump-shrug apex indicate that the landing forces produced during the jump shrug may be due to the landing strategy used by the athletes, especially at lighter loads. Practitioners may prescribe heavier loads during the jump-shrug exercise without viewing landing force as a potential limitation.
Intra-Personal and Inter-Personal Kinetic Synergies During Jumping
Directory of Open Access Journals (Sweden)
Slomka Kajetan
2015-12-01
Full Text Available We explored synergies between two legs and two subjects during preparation for a long jump into a target. Synergies were expected during one-person jumping. No such synergies were expected between two persons jumping in parallel without additional contact, while synergies were expected to emerge with haptic contact and become stronger with strong mechanical contact. Subjects performed jumps either alone (each foot standing on a separate force platform or in dyads (parallel to each other, each person standing on a separate force platform without any contact, with haptic contact, and with strong coupling. Strong negative correlations between pairs of force variables (strong synergies were seen in the vertical force in one-person jumps and weaker synergies in two-person jumps with the strong contact. For other force variables, only weak synergies were present in one-person jumps and no negative correlations between pairs of force variable for two-person jumps. Pairs of moment variables from the two force platforms at steady state showed positive correlations, which were strong in one-person jumps and weaker, but still significant, in two-person jumps with the haptic and strong contact. Anticipatory synergy adjustments prior to action initiation were observed in oneperson trials only. We interpret the different results for the force and moment variables at steady state as reflections of postural sway.
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. PMID:23936494
Effects of isometric scaling on vertical jumping performance.
Directory of Open Access Journals (Sweden)
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.
International Nuclear Information System (INIS)
Syphers, M.J.; Ahrens, L.; van Asselt, W.; Brennan, J.M.
1994-01-01
In an attempt to generate a lossless crossing of an accelerator's transition energy, one procedure is to alter the transition energy of the accelerator quickly as the beam passes through this energy region by changing the optics of the lattice -- a so-called ''transition jump,'' or '' γt -jump'' scheme. Such a system was first implemented at CERN and later adopted at other accelerator laboratories. A scheme for the AGS was developed in 1986. A description of the AGS γt -jump system, and recent results from its commissioning are presented in this report
Nonstandard jump functions for radically symmetric shock waves
International Nuclear Information System (INIS)
Baty, Roy S.; Tucker, Don H.; Stanescu, Dan
2008-01-01
Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables 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 physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function.
International Nuclear Information System (INIS)
Francis Maria Anand, L.; Gudennavar, S.B.; Bubbly, S.G.; Joseph, Daisy
2013-01-01
The article presents a simple method of measuring K-shell absorption jump ratios and jump factors for elements in the field of X-ray spectroscopy. The K-shell jump ratios and jump factors for Molybdenum and Silver are measured by adopting 2ŏ-geometrical configuration and a weak gamma source. The characteristic K X-ray photons are excited in the targets using 32.8 keV barium X-ray photons from a weak 137 Cs radioactive source that is produced due to the internal conversion of cesium nucleus (IC). The fluorescent K X-ray photons are detected using low energy Si(Li) detector coupled to a 8k multichannel analyser. The K X-ray intensity ratios from X-ray fluorescent spectrum are measured experimentally, the total atomic attenuation cross section and the total atomic scattering cross sections are calculated using WinXcom software. The K-shell jump factor and jump ratio are computed using the measured K X-ray intensity ratios and the calculated K a , X-ray production cross section. The computed values of K-shell jump factor and jump ratio for molybdenum and silver are compared with the theoretical values and others' experimental data and are presented. The amount of uncertainty in the experimental measurement of K X-ray intensity ratios is less than 5%. Thus the 2ŏ-geometrical configuration method with weak gamma source can be an alternative simple method to measure the jump factors and the jump ratios of pure elements in the field of X-ray spectroscopy. (author)
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 < 0.01) in young but not in the elderly. Correlations between H-reflex response and jumping parameters in young may indicate different jumping and activation 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.
Option Panels in Pure-Jump Settings
DEFF Research Database (Denmark)
Andersen, Torben Gustav; Fusari, Nicola; Todorov, Viktor
We develop parametric inference procedures for large panels of noisy option data in the setting where the underlying process is of pure-jump type, i.e., evolve only through a sequence of jumps. The panel consists of options written on the underlying asset with a (different) set of strikes...... specification for the risk-neutral asset return dynamics, the option prices are nonlinear functions of a time-invariant parameter vector and a time-varying latent state vector (or factors). Furthermore, no-arbitrage restrictions impose a direct link between some of the quantities that may be identified from...... the return and option data. These include the so-called jump activity index as well as the time-varying jump intensity. We propose penalized least squares estimation in which we minimize L_2 distance between observed and model-implied options and further penalize for the deviation of model-implied quantities...
Scaling the viscous circular hydraulic jump
Argentina, Mederic; Cerda, Enrique; Duchesne, Alexis; Limat, Laurent
2017-11-01
The formation mechanism of hydraulic jumps has been proposed by Belanger in 1828 and rationalised by Lord Rayleigh in 1914. As the Froude number becomes higher than one, the flow super criticality induces an instability which yields the emergence of a steep structure at the fluid surface. Strongly deformed liquid-air interface can be observed as a jet of viscous fluid impinges a flat boundary at high enough velocity. In this experimental setup, the location of the jump depends on the viscosity of the liquid, as shown by T. Bohr et al. in 1997. In 2014, A. Duchesne et al. have established the constancy of the Froude number at jump. Hence, it remains a contradiction, in which the radial hydraulic jump location might be explained through inviscid theory, but is also viscosity dependent. We present a model based on the 2011 Rojas et al. PRL, which solves this paradox. The agreement with experimental measurements is excellent not only for the prediction of the position of the hydraulic jump, but also for the determination of the fluid thickness profile. We predict theoretically the critical value of the Froude number, which matches perfectly to that measured by Duchesne et al. We acknowledge the support of the CNRS and the Universit Cte d'Azur, through the IDEX funding.
Jump phenomena. [large amplitude responses of nonlinear systems
Reiss, E. L.
1980-01-01
The paper considers jump phenomena composed of large amplitude responses of nonlinear systems caused by small amplitude disturbances. Physical problems where large jumps in the solution amplitude are important features of the response are described, including snap buckling of elastic shells, chemical reactions leading to combustion and explosion, and long-term climatic changes of the earth's atmosphere. A new method of rational functions was then developed which consists of representing the solutions of the jump problems as rational functions of the small disturbance parameter; this method can solve jump problems explicitly.
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...
DEFF Research Database (Denmark)
Lund, Ole; Ravn, Susanne; Christensen, Mette Krogh
2014-01-01
, in order to reach a deeper understanding of how practice facilitates learning. Results: We encircle the athletes’ interrelated learning processes by introducing the training environment of the national team and situations in which the athletes guide each other verbally or by jumping together. Discussion...
Effect of drop jump technique on the reactive strength index.
Struzik, Artur; Juras, Grzegorz; Pietraszewski, Bogdan; Rokita, Andrzej
2016-09-01
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 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 jump technique that is commonly performed by basketball players.
Kidon, Lyran; Wilner, Eli Y.; Rabani, Eran
2015-12-01
The generalized quantum master equation provides a powerful tool to describe the dynamics in quantum impurity models driven away from equilibrium. Two complementary approaches, one based on Nakajima-Zwanzig-Mori time-convolution (TC) and the other on the Tokuyama-Mori time-convolutionless (TCL) formulations provide a starting point to describe the time-evolution of the reduced density matrix. A key in both approaches is to obtain the so called "memory kernel" or "generator," going beyond second or fourth order perturbation techniques. While numerically converged techniques are available for the TC memory kernel, the canonical approach to obtain the TCL generator is based on inverting a super-operator in the full Hilbert space, which is difficult to perform and thus, nearly all applications of the TCL approach rely on a perturbative scheme of some sort. Here, the TCL generator is expressed using a reduced system propagator which can be obtained from system observables alone and requires the calculation of super-operators and their inverse in the reduced Hilbert space rather than the full one. This makes the formulation amenable to quantum impurity solvers or to diagrammatic techniques, such as the nonequilibrium Green's function. We implement the TCL approach for the resonant level model driven away from equilibrium and compare the time scales for the decay of the generator with that of the memory kernel in the TC approach. Furthermore, the effects of temperature, source-drain bias, and gate potential on the TCL/TC generators are discussed.
Dynamics and stability of directional jumps in the desert locust.
Gvirsman, Omer; Kosa, Gabor; Ayali, Amir
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.
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.
Bernatowicz, Piotr
2015-10-01
Theory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups has recently been given a consistently quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate, i.e., coherence-damping processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in condensed phase can retain quantum character over much broad temperature range than is commonly thought.
Impact of wave phase jumps on stochastic heating
International Nuclear Information System (INIS)
Zasenko, V.I.; Zagorodny, A.G.; Cherniak, O.M.
2016-01-01
Interaction of charged particles with fields of random waves brings about known effects of stochastic acceleration and heating. Jumps of wave phases can increase the intensity of these processes substantially. Numerical simulation of particle heating and acceleration by waves with regular phases, waves with jumping phase and stochastic electric field impulses is performed. Comparison of the results shows that to some extent an impact of phase jumps is similar to the action of separate field impulses. Jumps of phase not only increase the intensity of resonant particle heating but involves in this process non-resonant particles from a wide range of initial velocities
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...... dynamics. The volatility and jump intensity dynamics in the model are directly driven by model-free empirical measures of diffusive volatility and jump variation. Because the empirical measures are observed in discrete intervals, our option valuation model is cast in discrete time, allowing...... for straightforward filtering and estimation of the model. Our model belongs to the affine class enabling us to derive the conditional characteristic function so that option values can be computed rapidly without simulation. When estimated on S&P500 index options and returns the new model performs well compared...
Mesopause Jumps: Observations and Explanation
Luebken, F. J.; Becker, E.; Höffner, J.; Viehl, T. P.; Latteck, R.
2017-12-01
Recent high resolution temperature measurements by resonance lidar at Davis (69°S) occasionally showed a sudden mesopause altitude increase by 5km and an associated mesopause temperature decrease by 10K. 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 30m/s), and that the onset is not closely related to the transition of the stratospheric circulation.
Time in quantum mechanics. Vol. 1. 2. ed.
International Nuclear Information System (INIS)
Muga, J.G.; Sala Mayato, R.; Egusquiza, I.L.
2008-01-01
The treatment of time in quantum mechanics is still an important and challenging open question in the foundation of the quantum theory. This book describes the problems, and the attempts and achievements in defining, formalizing and measuring different time quantities in quantum theory, such as the parametric (clock) time, tunneling times, decay times, dwell times, delay times, arrival times or jump times. This multi-authored book, written as an introductory guide for newcomers to the subject, as well as a useful source of information for the expert, covers many of the open questions. After the brief historical overview in the introduction, 12 contributions are devoted to conceptual and theoretical investigations as well as experimental issues in quantum-mechanical time measurements. This novel monograph should attract physicists as well as philosophers of science working in the foundations of quantum physics. For this revised second edition, all chapters have been updated and extended where appropriate. (orig.)
Human Long Jump — A Deductive Approach
Directory of Open Access Journals (Sweden)
Miloš Jovanović
2012-10-01
Full Text Available This paper presents a useful application of a generalized approach to the modelling of human and humanoid motion using the deductive approach. It starts with formulating a completely general problem and deriving different real situations as special cases. The concept and the software realization are verified by comparing the results with the ones obtained using “classical” software for one well-known particular problem – biped walking. New applicability and potentials of the proposed method are demonstrated by simulation of a selected example – the long jump. The simulated motion included jumping and landing on the feet (after a jump. Additional analysis is done in the paper regarding the joint torque and joint angle during the jumping. Separate stages of the simulation are defined and explained.
Propulsion efficiency and imposed flow fields of a copepod jump
DEFF Research Database (Denmark)
Jiang, H.; Kiørboe, Thomas
2011-01-01
Pelagic copepods jump to relocate, to attack prey and to escape predators. However, there is a price to be paid for these jumps in terms of their energy costs and the hydrodynamic signals they generate to rheotactic predators. Using observed kinematics of various types of jumps, we computed...... the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump...... the flow structure. The flow field associated with an escape jump sequence also includes two dominant vortex structures: one leading wake vortex generated as a result of the first jump and one around the body, but between these two vortex structures is an elongated, long-lasting flow trail with flow...
Zvyagin, A. A.
2018-04-01
Based on the results of exact analytic calculations, we show that topological edge states and impurities in quantum dimerized chains manifest themselves in various local static and dynamical characteristics, which can be measured in experiments. In particular, topological edge states can be observed in the magnetic field behavior of the local magnetization or magnetic susceptibility of dimerized spin chains as jumps (for the magnetization) and features (for the static susceptibility) at zero field. In contrast, impurities reveal themselves in similar jumps and features, however, at nonzero values of the critical field. We also show that dynamical characteristics of dimerized quantum chains also manifest the features, related to the topological edge states and impurities. Those features, as a rule, can be seen more sharply than the manifestation of bulk extended states in, e.g., the dynamical local susceptibility. Such peculiarities can be observed in one-dimensional dimerized spin chains, e.g., in NMR experiments, or in various realizations of quantum dimerized chains in optical experiments.
The hydraulic jump and ripples in liquid helium
International Nuclear Information System (INIS)
Rolley, E.; Guthmann, C.; Pettersen, M.S.
2007-01-01
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 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
Numerical simulations of katabatic jumps in coats land, Antartica
Yu, Ye; Cai, Xiaoming; King, John C.; Renfrew, Ian A.
A non-hydrostatic numerical model, the Regional Atmospheric Modeling System (RAMS), has been used to investigate the development of katabatic jumps in Coats Land, Antarctica. In the control run with a 5 m s-1downslope directed initial wind, a katabatic jump develops near the foot of the idealized slope. The jump is manifested as a rapid deceleration of the downslope flow and a change from supercritical to subcritical flow, in a hydraulic sense, i.e., the Froude number (Fr) of the flow changes from Fr > 1 to Fr> 1. Results from sensitivity experiments show that an increase in the upstream flow rate strengthens the jump, while an increase in the downstream inversion-layer depth results in a retreat of the jump. Hydraulic theory and Bernoulli''s theorem have been used to explain the surface pressure change across the jump. It is found that hydraulic theory always underestimates the surface pressure change, while Bernoulli''s theorem provides a satisfactory estimation. An analysis of the downs balance for the katabatic jump indicates that the important forces are those related to the pressure gradient, advection and, to a lesser extent, the turbulent momentum divergence. The development of katabatic jumps can be divided into two phases. In phase I, the t gradient force is nearly balanced by advection, while in phase II, the pressure gradient force is counterbalanced by turbulent momentum divergence. The upslope pressure gradient force associated with a pool of cold air over the ice shelf facilitates the formation of the katabatic jump.
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.
Boundary conditions for open quantum systems driven far from equilibrium
Frensley, William R.
1990-07-01
This is a study of simple kinetic models of open systems, in the sense of systems that can exchange conserved particles with their environment. The system is assumed to be one dimensional and situated between two particle reservoirs. Such a system is readily driven far from equilibrium if the chemical potentials of the reservoirs differ appreciably. The openness of the system modifies the spatial boundary conditions on the single-particle Liouville-von Neumann equation, leading to a non-Hermitian Liouville operator. If the open-system boundary conditions are time reversible, exponentially growing (unphysical) solutions are introduced into the time dependence of the density matrix. This problem is avoided by applying time-irreversible boundary conditions to the Wigner distribution function. These boundary conditions model the external environment as ideal particle reservoirs with properties analogous to those of a blackbody. This time-irreversible model may be numerically evaluated in a discrete approximation and has been applied to the study of a resonant-tunneling semiconductor diode. The physical and mathematical properties of the irreversible kinetic model, in both its discrete and its continuum formulations, are examined in detail. The model demonstrates the distinction in kinetic theory between commutator superoperators, which may become non-Hermitian to describe irreversible behavior, and anticommutator superoperators, which remain Hermitian and are used to evaluate physical observables.
Moran, Kevin
2014-01-01
In high-income countries, death as a consequence of recreational jumping into water from height has not been well investigated partly because it traditionally has been a covert activity within youth culture. An observational study of video recordings posted on the YouTube web site was used to gather data on the nature of jumping activity in New Zealand and Australia. An analytical framework was developed to identify site- participant- social characteristics (10 variables) and online feedback (4 variables). Of the 389 videos recorded in New Zealand (n = 210) and Australia (n = 179), 929 jumpers were observed, and rivers were the most frequently reported site of jumping activity (New Zealand 47%; Australia 35%). One fifth (20%) of the jumps in New Zealand and one third (33%) in Australia were from heights estimated to be more than 12 m. The YouTube website portraying jumps from height were visited almost half a million times (495,686 hits). Ways of reducing recreational jumping risk via targeted education interventions may be best directed at young male adults. Use of social network sites to foster safe behaviours may be an effective way to educate young people of the inherent risks of jumping from height into water.
A simple strategy for jumping straight up.
Hemami, Hooshang; Wyman, Bostwick F
2012-05-01
Jumping from a stationary standing position into the air is a transition from a constrained motion in contact with the ground to an unconstrained system not in contact with the ground. A simple case of the jump, as it applies to humans, robots and humanoids, is studied in this paper. The dynamics of the constrained rigid body are expanded to define a larger system that accommodates the jump. The formulation is applied to a four-link, three-dimensional system in order to articulate the ballistic motion involved. The activity of the muscular system and the role of the major sagittal muscle groups are demonstrated. The control strategy, involving state feedback and central feed forward signals, is formulated and computer simulations are presented to assess the feasibility of the formulations, the strategy and the jump. Copyright © 2012 Elsevier Inc. All rights reserved.
Jumping robots: a biomimetic solution to locomotion across rough terrain.
Armour, Rhodri; Paskins, Keith; Bowyer, Adrian; Vincent, Julian; Megill, William; Bomphrey, Richard
2007-09-01
This paper introduces jumping robots as a means to traverse rough terrain; such terrain can pose problems for traditional wheeled, tracked and legged designs. The diversity of jumping mechanisms found in nature is explored to support the theory that jumping is a desirable ability for a robot locomotion system to incorporate, and then the size-related constraints are determined from first principles. A series of existing jumping robots are presented and their performance summarized. The authors present two new biologically inspired jumping robots, Jollbot and Glumper, both of which incorporate additional locomotion techniques of rolling and gliding respectively. Jollbot consists of metal hoop springs forming a 300 mm diameter sphere, and when jumping it raises its centre of gravity by 0.22 m and clears a height of 0.18 m. Glumper is of octahedral shape, with four 'legs' that each comprise two 500 mm lengths of CFRP tube articulating around torsion spring 'knees'. It is able to raise its centre of gravity by 1.60 m and clears a height of 1.17 m. The jumping performance of the jumping robot designs presented is discussed and compared against some specialized jumping animals. Specific power output is thought to be the performance-limiting factor for a jumping robot, which requires the maximization of the amount of energy that can be stored together with a minimization of mass. It is demonstrated that this can be achieved through optimization and careful materials selection.
Rebilas, Krzysztof
2013-02-01
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 α. What is the optimal angle α that makes the jump the longest possible for the fixed magnitude of the velocity V? Of course, in practice, this is a very sophisticated problem; the skier's range depends on a variety of complex factors in addition to V and α. However, if we ignore these and assume the jumper is in free fall between the takeoff ramp and the landing point below, the problem becomes an exercise in kinematics that is suitable for introductory-level students. The solution is presented here.
Bernatowicz, Piotr; Shkurenko, Aleksander; Osior, Agnieszka; Kamieński, Bohdan; Szymański, Sławomir
2015-11-21
The theory of nuclear spin-lattice relaxation in methyl groups in solids has been a recurring problem in nuclear magnetic resonance (NMR) spectroscopy. The current view is that, except for extreme cases of low torsional barriers where special quantum effects are at stake, the relaxation behaviour of the nuclear spins in methyl groups is controlled by thermally activated classical jumps of the methyl group between its three orientations. The temperature effects on the relaxation rates can be modelled by Arrhenius behaviour of the correlation time of the jump process. The entire variety of relaxation effects in protonated methyl groups have recently been given a consistent quantum mechanical explanation not invoking the jump model regardless of the temperature range. It exploits the damped quantum rotation (DQR) theory originally developed to describe NMR line shape effects for hindered methyl groups. In the DQR model, the incoherent dynamics of the methyl group include two quantum rate (i.e., coherence-damping) processes. For proton relaxation only one of these processes is relevant. In this paper, temperature-dependent proton spin-lattice relaxation data for the methyl groups in polycrystalline methyltriphenyl silane and methyltriphenyl germanium, both deuterated in aromatic positions, are reported and interpreted in terms of the DQR model. A comparison with the conventional approach exploiting the phenomenological Arrhenius equation is made. The present observations provide further indications that incoherent motions of molecular moieties in the condensed phase can retain quantum character over much broader temperature range than is commonly thought.
Anthropic prediction for a large multi-jump landscape
International Nuclear Information System (INIS)
Schwartz-Perlov, Delia
2008-01-01
The assumption of a flat prior distribution plays a critical role in the anthropic prediction of the cosmological constant. In a previous paper we analytically calculated the distribution for the cosmological constant, including the prior and anthropic selection effects, in a large toy 'single-jump' landscape model. We showed that it is possible for the fractal prior distribution that we found to behave as an effectively flat distribution in a wide class of landscapes, but only if the single-jump size is large enough. We extend this work here by investigating a large (N∼10 500 ) toy 'multi-jump' landscape model. The jump sizes range over three orders of magnitude and an overall free parameter c determines the absolute size of the jumps. We will show that for 'large' c the distribution of probabilities of vacua in the anthropic range is effectively flat, and thus the successful anthropic prediction is validated. However, we argue that for small c, the distribution may not be smooth
Scaling and jumping: Gravity loses grip on small jumpers
Scholz, M.N.; Bobbert, M.F.; van Soest, A.J.
2006-01-01
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
Yang, Eunjin; Kim, Ho-Young
2015-11-01
Small aquatic arthropods, such as water striders and fishing spiders, are able to jump off water to a height several times their body length. Inspired by the unique biological motility on water, we study a simple model using a flexible hoop to provide fundamental understanding and a mimicking principle of small jumpers on water. Behavior of a hoop on water, which is coated with superhydrophobic particles and initially bent into an ellipse from an equilibrium circular shape, is visualized with a high speed camera upon launching it into air by releasing its initial elastic strain energy. We observe that jumping of our hoops is dominated by the dynamic pressure of water rather than surface tension, and thus it corresponds to the dynamic condition experienced by fishing spiders. We calculate the reaction forces provided by water adopting the unsteady Bernoulli equation as well as the momentum loss into liquid inertia and viscous friction. Our analysis allows us to predict the jumping efficiency of the hoop on water in comparison to that on ground, and to discuss the evolutionary pressure rendering fishing spiders select such dynamic behavior.
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.
Variability of Plyometric and Ballistic Exercise Technique Maintains Jump Performance.
Chandler, Phillip T; Greig, Matthew; Comfort, Paul; McMahon, John J
2018-06-01
Chandler, PT, Greig, M, Comfort, P, and McMahon, JJ. Variability of plyometric and ballistic exercise technique maintains jump performance. J Strength Cond Res 32(6): 1571-1582, 2018-The aim of this study was to investigate changes in vertical jump technique over the course of a training session. Twelve plyometric and ballistic exercise-trained male athletes (age = 23.4 ± 4.6 years, body mass = 78.7 ± 18.8 kg, height = 177.1 ± 9.0 cm) performed 3 sets of 10 repetitions of drop jump (DJ), rebound jump (RJ) and squat jump (SJ). Each exercise was analyzed from touchdown to peak joint flexion and peak joint flexion to take-off. Squat jump was analyzed from peak joint flexion to take-off only. Jump height, flexion and extension time and range of motion, and instantaneous angles of the ankle, knee, and hip joints were measured. Separate 1-way repeated analyses of variance compared vertical jump technique across exercise sets and repetitions. Exercise set analysis found that SJ had lower results than DJ and RJ for the angle at peak joint flexion for the hip, knee, and ankle joints and take-off angle of the hip joint. Exercise repetition analysis found that the ankle joint had variable differences for the angle at take-off, flexion, and extension time for RJ. The knee joint had variable differences for flexion time for DJ and angle at take-off and touchdown for RJ. There was no difference in jump height. Variation in measured parameters across repetitions highlights variable technique across plyometric and ballistic exercises. This did not affect jump performance, but likely maintained jump performance by overcoming constraints (e.g., level of rate coding).
Influence of magnetic history on flux jump fields
International Nuclear Information System (INIS)
Sosnowski, J.
1986-01-01
A formalism describing the fields at which flux jumps occur in hard superconductors has been confirmed by the description of an experimentally observed shift of flux jump fields in the second hysteresis loop of a Nb 3 Al superconducting sample. By fitting the theoretical model to experimental data, values of the proportionality parameter between the stability limit and the flux jump field, the first stability limit, and the first penetration field have been estimated
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
Dissipative - free jumps for the magnetoacoustic branch of cold plasma motions
International Nuclear Information System (INIS)
Bakholdin, I.B.
2000-01-01
Dissipative-free jumps were studied in hydrodynamic model of cold plasma moving with the rate close to magnetoacoustic one. The jumps for the generalized Korteweg-de Vries equation with similar nonlinear and dispersion properties were studied. Among them there were jumps with emission and solution type jumps. Furthermore, the numerical investigation into the initial break decomposition in cold plasma confirmed the validity of assumption that in the given type of jumps as in case of the generalized Korteweg-de Vries equation. Paper describes the analytical method enabling to forecast the structure nature of such jumps in the general case [ru
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...... market portfolio, we find that the distributions of the systematic and idiosyncratic jumps are both generally heavy-tailed and not necessarily symmetric. Our estimates also point to the existence of strong dependencies between the market-wide jumps and the corresponding systematic jump tails for all...... of the stocks in the sample. We also show how the jump tail dependencies deduced from the high-frequency data together with the day-to-day temporal variation in the volatility are able to explain the “extreme” dependencies vis-a-vis the market portfolio....
Numerical study of laminar, standing hydraulic jumps in a planar geometry.
Dasgupta, Ratul; Tomar, Gaurav; Govindarajan, Rama
2015-05-01
We solve the two-dimensional, planar Navier-Stokes equations to simulate a laminar, standing hydraulic jump using a Volume-of-Fluid method. The geometry downstream of the jump has been designed to be similar to experimental conditions by including a pit at the edge of the platform over which liquid film flows. We obtain jumps with and without separation. Increasing the inlet Froude number pushes the jump downstream and makes the slope of the jump weaker, consistent with experimental observations of circular jumps, and decreasing the Reynolds number brings the jump upstream while making it steeper. We study the effect of the length of the domain and that of a downstream obstacle on the structure and location of the jump. The transient flow which leads to a final steady jump is described for the first time to our knowledge. In the moderate Reynolds number regime, we obtain steady undular jumps with a separated bubble underneath the first few undulations. Interestingly, surface tension leads to shortening of wavelength of these undulations. We show that the undulations can be explained using the inviscid theory of Benjamin and Lighthill (Proc. R. Soc. London, Ser. A, 1954). We hope this new finding will motivate experimental verification.
International Nuclear Information System (INIS)
Kaya, N.; Apaydin, G.; Tirasoglu, E.
2011-01-01
This article presents experimental values of the K-shell jump factor and jump ratio (ratio of the K-shell photoionization cross section to the photoionization cross section of the rest of the atom at the K edge) for some elements in 76≤Z≤92 using an energy dispersive X-ray fluorescence (EDXRF) spectrometer and compares those values with the theoretical ones giving reasonable agreement. The experimental values have been determined using the fluorescence parameters: K α production cross sections, K β /K α X-rays intensity ratios, total atomic attenuation cross sections, etc. To the best of our knowledge, K-shell jump ratios and jump factors have been measured without having any data on K edge for the first time in these elements. The results have been plotted versus atomic number.
Quantum trajectories for time-dependent adiabatic master equations
Yip, Ka Wa; Albash, Tameem; Lidar, Daniel A.
2018-02-01
We describe a quantum trajectories technique for the unraveling of the quantum adiabatic master equation in Lindblad form. By evolving a complex state vector of dimension N instead of a complex density matrix of dimension N2, simulations of larger system sizes become feasible. The cost of running many trajectories, which is required to recover the master equation evolution, can be minimized by running the trajectories in parallel, making this method suitable for high performance computing clusters. In general, the trajectories method can provide up to a factor N advantage over directly solving the master equation. In special cases where only the expectation values of certain observables are desired, an advantage of up to a factor N2 is possible. We test the method by demonstrating agreement with direct solution of the quantum adiabatic master equation for 8-qubit quantum annealing examples. We also apply the quantum trajectories method to a 16-qubit example originally introduced to demonstrate the role of tunneling in quantum annealing, which is significantly more time consuming to solve directly using the master equation. The quantum trajectories method provides insight into individual quantum jump trajectories and their statistics, thus shedding light on open system quantum adiabatic evolution beyond the master equation.
Temperature jump boundary conditions in radiation diffusion
International Nuclear Information System (INIS)
Alonso, C.T.
1976-12-01
The radiation diffusion approximation greatly simplifies radiation transport problems. Yet the application of this method has often been unnecessarily restricted to optically thick regions, or has been extended through the use of such ad hoc devices as flux limiters. The purpose of this paper is to review and draw attention to the use of the more physically appropriate temperature jump boundary conditions for extending the range of validity of the diffusion approximation. Pioneering work has shown that temperature jump boundary conditions remove the singularity in flux that occurs in ordinary diffusion at small optical thicknesses. In this review paper Deissler's equations for frequency-dependent jump boundary conditions are presented and specific geometric examples are calculated analytically for steady state radiation transfer. When jump boundary conditions are applied to radiation diffusion, they yield exact solutions which are naturally flux- limited and geometry-corrected. We believe that the presence of temperature jumps on source boundaries is probably responsible in some cases for the past need for imposing ad hoc flux-limiting constraints on pure diffusion solutions. The solution for transfer between plane slabs, which is exact to all orders of optical thickness, also provides a useful tool for studying the accuracy of computer codes
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
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
Biomechanics of stair walking and jumping.
Loy, D J; Voloshin, A S
1991-01-01
Physical activities such as stair walking and jumping result in increased dynamic loading on the human musculoskeletal system. Use of light weight, externally attached accelerometers allows for in-vivo monitoring of the shock waves invading the human musculoskeletal system during those activities. Shock waves were measured in four subjects performing stair walking up and down, jumping in place and jumping off a fixed elevation. The results obtained show that walking down a staircase induced shock waves with amplitude of 130% of that observed in walking up stairs and 250% of the shock waves experienced in level gait. The jumping test revealed levels of the shock waves nearly eight times higher than that in level walking. It was also shown that the shock waves invading the human musculoskeletal system may be generated not only by the heel strike, but also by the metatarsal strike. To moderate the risk of degenerative joint disorders four types of viscoelastic insoles were utilized to reduce the impact generated shock waves. The insoles investigated were able to reduce the amplitude of the shock wave by between 9% and 41% depending on the insole type and particular physical activity. The insoles were more effective in the reduction of the heel strike impacts than in the reduction of the metatarsal strike impacts. In all instances, the shock attenuation capacities of the insoles tested were greater in the jumping trials than in the stair walking studies. The insoles were ranked in three groups on the basis of their shock absorbing capacity.
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.
Immediate Effects of Different Trunk Exercise Programs on Jump Performance.
Imai, A; Kaneoka, K; Okubo, Y; Shiraki, H
2016-03-01
The aim of this study was to investigate the immediate effects of trunk stabilization exercise (SE) and conventional trunk exercise (CE) programs on jump performance. 13 adolescent male soccer players performed 2 kinds of jump testing before and immediate after 3 experimental conditions: SE, CE, and non-exercise (NE). The SE program consisted of the elbow-toe, hand-knee, and back bridge, and the CE program consisted of the sit-up, sit-up with trunk rotation and back extension. Testing of a countermovement jump (CMJ) and rebound jump (RJ) were performed to assess jump performance. Jump height of the CMJ and RJ-index, contact time, and jump height of the RJ were analyzed. The RJ index was improved significantly only after SE (p=0.017). However, contact time and jump height did not improve significantly in the SE condition. Moreover, no significant interaction or main effects of time or group were observed in the CMJ. Consequently, this study showed the different immediate effect on the RJ between the SE and CE, and suggested the possibility that the SE used in this study is useful as a warm-up program to improve the explosive movements. © Georg Thieme Verlag KG Stuttgart · New York.
Dissipation-Free Jumps for the Magnetosonic Branch of Cold Plasma Motion
International Nuclear Information System (INIS)
Bakholdin, I.B.
2000-01-01
Dissipation-free jumps are studied in a hydrodynamic model of a cold plasma moving at about magnetosonic speed. The jumps described by the generalized Korteweg-de Vries equation, which possesses similar nonlinear and dispersion properties, are considered. In particular, jumps with emission and solitonlike jumps are considered. The assumption that our model possesses jumps of the same type as those for the generalized Korteweg-de Vries equation is justified by numerically investigating the problem of the decay of an initial discontinuity in a cold plasma. An analytic method is described that makes it possible to predict the structure of such jumps in the general case
Biomechanical analysis of drop and countermovement jumps
Bobbert, M. F.; Mackay, M.T.; Schinkelshoek, D.; Huijing, P. A.; van Ingen Schenau, G. J.
For 13 subjects the performance of drop jumps from a height of 40 cm (DJ) and of countermovement jumps (CMJ) was analysed and compared. From force plate and cine data biomechanical variables including forces, moments, power output and amount of work done were calculated for hip, knee and ankle
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...
DEFF Research Database (Denmark)
Fasterhold, Martin; Pichlmair, Martin; Holmgård, Christoffer
This paper explores the design of jumping in 2D platform games. Through creating a method for measuring existing games, applying this method to a selection of different platformer games, and analysing the results, the paper arrives at a comprehensive data model for jumping. The model supports the...
Thomas, Brandon J; Hawkins, Matthew M; Nalepka, Patrick
2017-03-30
Runeson (Scandanavian Journal of Psychology 18:172-179, 1977) suggested that the polar planimeter might serve as an informative model system of perceptual mechanism. The key aspect of the polar planimeter is that it registers a higher order property of the environment without computational mediation on the basis of lower order properties, detecting task-specific information only. This aspect was posited as a hypothesis for the perception of jumping and reaching affordances for the self and another person. The findings supported this hypothesis. The perception of reaching while jumping significantly differed from an additive combination of jump-without-reaching and reach-without-jumping perception. The results are consistent with Gibson's (The senses considered as perceptual systems, Houghton Mifflin, Boston, MA; Gibson, The senses considered as perceptual systems, Houghton Mifflin, Boston, MA, 1966; The ecological approach to visual perception, Houghton Mifflin, Boston, MA; Gibson, The ecological approach to visual perception, Houghton Mifflin, Boston, MA, 1979) theory of information-that aspects of the environment are specified by patterns in energetic media.
Lower Extremity Kinematics Differed Between a Controlled Drop-Jump and Volleyball-Takeoffs.
Beardt, Bradley S; McCollum, Myranda R; Hinshaw, Taylour J; Layer, Jacob S; Wilson, Margaret A; Zhu, Qin; Dai, Boyi
2018-04-03
Previous studies utilizing jump-landing biomechanics to predict anterior cruciate ligament injuries have shown inconsistent findings. The purpose of this study was to quantify the differences and correlations in jump-landing kinematics between a drop-jump, a controlled volleyball-takeoff, and a simulated-game volleyball-takeoff. Seventeen female volleyball players performed these three tasks on a volleyball court while three-dimensional kinematic data were collected by three calibrated camcorders. Participants demonstrated significantly increased jump height, shorter stance time, increased time differences in initial contact between two feet, increased knee and hip flexion at initial contact and decreased peak knee and hip flexion for both left and right legs, and decreased knee-ankle distance ratio at the lowest height of mid-hip for the two volleyball-takeoffs compared with the drop-jump (p jump and two volleyball-takeoffs. Controlled drop-jump kinematics may not represent jump-landing kinematics exhibited during volleyball competition. Jump-landing mechanics during sports-specific tasks may better represent those exhibited during sports competition and their associated risk of ACL injury compared with the drop-jump.
Holographic control of information and dynamical topology change for composite open quantum systems
Aref'eva, I. Ya.; Volovich, I. V.; Inozemcev, O. V.
2017-12-01
We analyze how the compositeness of a system affects the characteristic time of equilibration. We study the dynamics of open composite quantum systems strongly coupled to the environment after a quantum perturbation accompanied by nonequilibrium heating. We use a holographic description of the evolution of entanglement entropy. The nonsmooth character of the evolution with holographic entanglement is a general feature of composite systems, which demonstrate a dynamical change of topology in the bulk space and a jumplike velocity change of entanglement entropy propagation. Moreover, the number of jumps depends on the system configuration and especially on the number of composite parts. The evolution of the mutual information of two composite systems inherits these jumps. We present a detailed study of the mutual information for two subsystems with one of them being bipartite. We find five qualitatively different types of behavior of the mutual information dynamics and indicate the corresponding regions of the system parameters.
Planar Quantum Mechanics: an Intriguing Supersymmetric Example
Veneziano, Gabriele
2006-01-01
After setting up a Hamiltonian formulation of planar (matrix) quantum mechanics, we illustrate its effectiveness in a non-trivial supersymmetric example. The numerical and analytical study of two sectors of the model, as a function of 't Hooft's coupling $\\lambda$, reveals both a phase transition at $\\lambda=1$ (disappearence of the mass gap and discontinuous jump in Witten's index) and a new form of strong-weak duality for $\\lambda \\to 1/\\lambda$.
The Perpetual American Put Option for Jump-Diffusions
Aase, Knut K.
2010-01-01
-This is the author's version of the article"The Perpetual American Put Option for Jump-Diffusions" Energy Systems pp 493-507. We solve a specific optimal stopping problem with an infinite time horizon, when the state variable follows a jump-diffusion. The novelty of the paper is related to the inclusion of a jump component in this stochastic process. Under certain conditions, our solution can be interpreted as the price of an American perpetual put option. We characterize the continuation...
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...17026 7 Temperature Jump Pyrolysis at AFRL Edwards Rapid heating of a metal filament at a rate of 600 – 800 K/s, and the set temperature is held for
Diarylethene microcrystals make directional jumps upon ultraviolet irradiation
International Nuclear Information System (INIS)
Colombier, I.; Spagnoli, S.; Corval, A.; Baldeck, P. L.; Giraud, M.; Leaustic, A.; Yu, P.; Irie, M.
2007-01-01
Microcrystals of a diarylethene {1,2-bis[5 ' -methyl-2 ' -(2 '' -pyridyl)thiazolyl]perfluorocyclo-pentene } undergo jumps upon photoirradiation. These photochromic crystals present molecular structural changes upon irradiation with ultraviolet light because of reversible photocyclization reactions. When the energy absorbed by crystals reaches about 10 μJ, the uniaxial stress induced in the crystal lattice relaxes through directional jumps. If one prevents crystals from jumping, then parallel, equidistant cracks appear on crystal surfaces. These photomechanical effects could result from a Grinfeld surface instability
Model for calorimetric measurements in an open quantum system
Donvil, Brecht; Muratore-Ginanneschi, Paolo; Pekola, Jukka P.; Schwieger, Kay
2018-05-01
We investigate the experimental setup proposed in New J. Phys. 15, 115006 (2013), 10.1088/1367-2630/15/11/115006 for calorimetric measurements of thermodynamic indicators in an open quantum system. As a theoretical model we consider a periodically driven qubit coupled with a large yet finite electron reservoir, the calorimeter. The calorimeter is initially at equilibrium with an infinite phonon bath. As time elapses, the temperature of the calorimeter varies in consequence of energy exchanges with the qubit and the phonon bath. We show how under weak-coupling assumptions, the evolution of the qubit-calorimeter system can be described by a generalized quantum jump process including as dynamical variable the temperature of the calorimeter. We study the jump process by numeric and analytic methods. Asymptotically with the duration of the drive, the qubit-calorimeter attains a steady state. In this same limit, we use multiscale perturbation theory to derive a Fokker-Planck equation governing the calorimeter temperature distribution. We inquire the properties of the temperature probability distribution close and at the steady state. In particular, we predict the behavior of measurable statistical indicators versus the qubit-calorimeter coupling constant.
Distribution of tunnelling times for quantum electron transport
International Nuclear Information System (INIS)
Rudge, Samuel L.; Kosov, Daniel S.
2016-01-01
In electron transport, the tunnelling time is the time taken for an electron to tunnel out of a system after it has tunnelled in. We define the tunnelling time distribution for quantum processes in a dissipative environment and develop a practical approach for calculating it, where the environment is described by the general Markovian master equation. We illustrate the theory by using the rate equation to compute the tunnelling time distribution for electron transport through a molecular junction. The tunnelling time distribution is exponential, which indicates that Markovian quantum tunnelling is a Poissonian statistical process. The tunnelling time distribution is used not only to study the quantum statistics of tunnelling along the average electric current but also to analyse extreme quantum events where an electron jumps against the applied voltage bias. The average tunnelling time shows distinctly different temperature dependence for p- and n-type molecular junctions and therefore provides a sensitive tool to probe the alignment of molecular orbitals relative to the electrode Fermi energy.
Jump as Far as You Can [Problem Solvers: Problem
Bofferding, Laura; Yigit, Melike
2013-01-01
The standing long jump was an Olympic event until 1912. In 1904, Ray Ewry set the world record for the longest standing long jump, which was about 11.5 feet, or 138 inches. Although the standing long jump is no longer an Olympic event, the Norwegians still include it in their National Competition, and Arne Tvervaag set a new world record at about…
Thomson's Jumping Ring over a Long Coil
Jeffery, Rondo N.; Amiri, Farhang
2018-01-01
The classic jumping ring apparatus consists of a coil with an iron core that extends out of the coil. A copper or aluminum ring placed over the iron core jumps upward when AC power is applied to the coil. In this paper we will examine a modified design of the jumping ring apparatus, called the "long-coil design." It allows the ring to…
Isokinetic Extension Strength Is Associated With Single-Leg Vertical Jump Height.
Fischer, Felix; Blank, Cornelia; Dünnwald, Tobias; Gföller, Peter; Herbst, Elmar; Hoser, Christian; Fink, Christian
2017-11-01
Isokinetic strength testing is an important tool in the evaluation of the physical capacities of athletes as well as for decision making regarding return to sports after anterior cruciate ligament (ACL) reconstruction in both athletes and the lay population. However, isokinetic testing is time consuming and requires special testing equipment. A single-jump test, regardless of leg dominance, may provide information regarding knee extension strength through the use of correlation analysis of jump height and peak torque of isokinetic muscle strength. Cross-sectional study; Level of evidence, 3. A total of 169 patients who underwent ACL reconstruction were included in this study. Isokinetic testing was performed on the injured and noninjured legs. Additionally, a single-leg countermovement jump was performed to assess jump height using a jump accelerometer sensor. Extension strength values were used to assess the association between isokinetic muscle strength and jump height. The sample consisted of 60 female (mean age, 20.8 ± 8.3 years; mean weight, 61.7 ± 6.5 kg; mean height, 167.7 ± 5.3 cm) and 109 male (mean age, 23.2 ± 7.7 years; mean weight, 74.6 ± 10.2 kg; mean height, 179.9 ± 6.9 cm) patients. Bivariate correlation analysis showed an association ( r = 0.56, P jump height and isokinetic extension strength on the noninvolved side as well as an association ( r = 0.52, P jump height (beta = 0.49, P jump height having the strongest impact (beta = 0.49, P jump height. The study population encompassed various backgrounds, skill levels, and activity profiles, which might have affected the outcome. Even after controlling for age and sex, isokinetic strength was still moderately associated with jump height. Therefore, the jump technique and type of sport should be considered in future research.
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.
Effect of early training on the jumping technique of horses
Santamaría, Susana; Bobbert, Maarten F.; Back, Willem; Barneveld, Ab; van Weeren, P. Rene
Objective - 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. Animals - 40 Dutch Warmblood horses. Procedure - The horses were analyzed kinematically during free jumping at
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...
Energy Technology Data Exchange (ETDEWEB)
Kidon, Lyran [School of Chemistry, The Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978 (Israel); Wilner, Eli Y. [School of Physics and Astronomy, The Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 69978 (Israel); Rabani, Eran [The Sackler Center for Computational Molecular and Materials Science, Tel Aviv University, Tel Aviv 69978 (Israel); Department of Chemistry, University of California and Lawrence Berkeley National Laboratory, Berkeley California 94720-1460 (United States)
2015-12-21
The generalized quantum master equation provides a powerful tool to describe the dynamics in quantum impurity models driven away from equilibrium. Two complementary approaches, one based on Nakajima–Zwanzig–Mori time-convolution (TC) and the other on the Tokuyama–Mori time-convolutionless (TCL) formulations provide a starting point to describe the time-evolution of the reduced density matrix. A key in both approaches is to obtain the so called “memory kernel” or “generator,” going beyond second or fourth order perturbation techniques. While numerically converged techniques are available for the TC memory kernel, the canonical approach to obtain the TCL generator is based on inverting a super-operator in the full Hilbert space, which is difficult to perform and thus, nearly all applications of the TCL approach rely on a perturbative scheme of some sort. Here, the TCL generator is expressed using a reduced system propagator which can be obtained from system observables alone and requires the calculation of super-operators and their inverse in the reduced Hilbert space rather than the full one. This makes the formulation amenable to quantum impurity solvers or to diagrammatic techniques, such as the nonequilibrium Green’s function. We implement the TCL approach for the resonant level model driven away from equilibrium and compare the time scales for the decay of the generator with that of the memory kernel in the TC approach. Furthermore, the effects of temperature, source-drain bias, and gate potential on the TCL/TC generators are discussed.
Muller, Andreas
2013-01-01
On October 14,2012, Felix Baumgartner, an Austrian sky-diver, set some new world records for his discipline. Jumping from a height of about 39 km, he reached a top speed of 1342 km/h, becoming the first human being to break the sound barrier in free fall. In order to understand some essential physics aspects of this remarkable feat, we wonder why…
Ballistic Jumping Drops on Superhydrophobic Surfaces via Electrostatic Manipulation.
Li, Ning; Wu, Lei; Yu, Cunlong; Dai, Haoyu; Wang, Ting; Dong, Zhichao; Jiang, Lei
2018-02-01
The ballistic ejection of liquid drops by electrostatic manipulating has both fundamental and practical implications, from raindrops in thunderclouds to self-cleaning, anti-icing, condensation, and heat transfer enhancements. In this paper, the ballistic jumping behavior of liquid drops from a superhydrophobic surface is investigated. Powered by the repulsion of the same kind of charges, water drops can jump from the surface. The electrostatic acting time for the jumping of a microliter supercooled drop only takes several milliseconds, even shorter than the time for icing. In addition, one can control the ballistic jumping direction precisely by the relative position above the electrostatic field. The approach offers a facile method that can be used to manipulate the ballistic drop jumping via an electrostatic field, opening the possibility of energy efficient drop detaching techniques in various applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Jumping-droplet electronics hot-spot cooling
Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle; Neely, Jason; Pilawa-Podgurski, Robert C. N.; Miljkovic, Nenad
2017-03-01
Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm × 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25 °C air temperature, 20%-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm) and applied heat flux (demonstrated to 13 W/cm2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm2. This work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.
Jumping-droplet electronics hot-spot cooling
International Nuclear Information System (INIS)
Oh, Junho; Birbarah, Patrick; Foulkes, Thomas; Yin, Sabrina L.; Rentauskas, Michelle
2017-01-01
Demand for enhanced cooling technologies within various commercial and consumer applications has increased in recent decades due to electronic devices becoming more energy dense. This study demonstrates jumping-droplet based electric-field-enhanced (EFE) condensation as a potential method to achieve active hot spot cooling in electronic devices. To test the viability of EFE condensation, we developed an experimental setup to remove heat via droplet evaporation from single and multiple high power gallium nitride (GaN) transistors acting as local hot spots (4.6 mm x 2.6 mm). An externally powered circuit was developed to direct jumping droplets from a copper oxide (CuO) nanostructured superhydrophobic surface to the transistor hot spots by applying electric fields between the condensing surface and the transistor. Heat transfer measurements were performed in ambient air (22-25°C air temperature, 20-45% relative humidity) to determine the effect of gap spacing (2-4 mm), electric field (50-250 V/cm), and heat flux (demonstrated to 13 W/cm"2). EFE condensation was shown to enhance the heat transfer from the local hot spot by ≈ 200% compared to cooling without jumping and by 20% compared to non-EFE jumping. Dynamic switching of the electric field for a two-GaN system reveals the potential for active cooling of mobile hot spots. The opportunity for further cooling enhancement by the removal of non-condensable gases promises hot spot heat dissipation rates approaching 120 W/cm"2. Finally, this work provides a framework for the development of active jumping droplet based vapor chambers and heat pipes capable of spatial and temporal thermal dissipation control.
Improvement of Long-Jump Performance During Competition Using a Plyometric Exercise.
Bogdanis, Gregory C; Tsoukos, Athanasios; Veligekas, Panagiotis
2017-02-01
To examine the acute effects of a conditioning plyometric exercise on long-jump performance during a simulated long-jump competition. Eight national-level track and field decathletes performed 6 long-jump attempts with a full approach run separated by 10-min recoveries. In the experimental condition subjects performed 3 rebound vertical jumps with maximal effort 3 min before the last 5 attempts, while the 1st attempt served as baseline. In the control condition the participants performed 6 long jumps without executing the conditioning exercise. Compared with baseline, long-jump performance progressively increased only in the experimental condition, from 3.0%, or 17.5 cm, in the 3rd attempt (P = .046, d = 0.56), to 4.8%, or 28.2 cm, in the 6th attempt (P = .0001, d = 0.84). The improvement in long-jump performance was due to a gradual increase in vertical takeoff velocity from the 3rd (by 8.7%, P = .0001, d = 1.82) to the 6th jump (by 17.7%, P = .0001, d = 4.38). Horizontal-approach velocity, takeoff duration, and horizontal velocity at takeoff were similar at all long-jump attempts in both conditions (P = .80, P = .36, and P = .15, respectively). Long-jump performance progressively improved during a simulated competition when a plyometric conditioning exercise was executed 3 min before each attempt. This improvement was due to a progressive increase in vertical velocity of takeoff, while there was no effect on the horizontal velocity.
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.
Jumps in binomial AR(1) processes
Weiß , Christian H.
2009-01-01
Abstract We consider the binomial AR(1) model for serially dependent processes of binomial counts. After a review of its definition and known properties, we investigate marginal and serial properties of jumps in such processes. Based on these results, we propose the jumps control chart for monitoring a binomial AR(1) process. We show how to evaluate the performance of this control chart and give design recommendations. correspondance: Tel.: +49 931 31 84968; ...
Recent Advancements in Lightning Jump Algorithm Work
Schultz, Christopher J.; Petersen, Walter A.; Carey, Lawrence D.
2010-01-01
In the past year, the primary objectives were to show the usefulness of total lightning as compared to traditional cloud-to-ground (CG) networks, test the lightning jump algorithm configurations in other regions of the country, increase the number of thunderstorms within our thunderstorm database, and to pinpoint environments that could prove difficult for any lightning jump configuration. A total of 561 thunderstorms have been examined in the past year (409 non-severe, 152 severe) from four regions of the country (North Alabama, Washington D.C., High Plains of CO/KS, and Oklahoma). Results continue to indicate that the 2 lightning jump algorithm configuration holds the most promise in terms of prospective operational lightning jump algorithms, with a probability of detection (POD) at 81%, a false alarm rate (FAR) of 45%, a critical success index (CSI) of 49% and a Heidke Skill Score (HSS) of 0.66. The second best performing algorithm configuration was the Threshold 4 algorithm, which had a POD of 72%, FAR of 51%, a CSI of 41% and an HSS of 0.58. Because a more complex algorithm configuration shows the most promise in terms of prospective operational lightning jump algorithms, accurate thunderstorm cell tracking work must be undertaken to track lightning trends on an individual thunderstorm basis over time. While these numbers for the 2 configuration are impressive, the algorithm does have its weaknesses. Specifically, low-topped and tropical cyclone thunderstorm environments are present issues for the 2 lightning jump algorithm, because of the suppressed vertical depth impact on overall flash counts (i.e., a relative dearth in lightning). For example, in a sample of 120 thunderstorms from northern Alabama that contained 72 missed events by the 2 algorithm 36% of the misses were associated with these two environments (17 storms).
Vertical jump fatigue does not affect intersegmental coordination and segmental contribution
Directory of Open Access Journals (Sweden)
Gleber Pereira
2014-09-01
Full Text Available The aim of this study was to describe the intersegmental coordination and segmental contribution during intermittent vertical jumps performed until fatigue. Seven male visited the laboratory on two occasions: 1 the maximum vertical jump height was determined followed by vertical jumps habituation; 2 participants performed intermittent countermovement jumps until fatigue. Kinematic and kinetic variables were recorded. The overall reduction in vertical jump height was 5,5%, while the movement duration increased 10% during the test. The thigh segment angle at movement reversal significantly increased as the exercise progressed. Non-significant effect of fatigue on movement synergy was found for the intersegmental coordination pattern. More than 90% of the intersegmental coordination was explained by one coordination pattern. Thigh rotation contributed the most to the intersegmental coordination pattern, with the trunk second and the shank the least. Therefore, one intersegmental coordination pattern is followed throughout the vertical jumps until fatigue and thigh rotation contributes the most to jump height.
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.
Nikolaidis, Pantelis T; Gkoudas, Konstantinos; Afonso, José; Clemente-Suarez, Vicente J; Knechtle, Beat; Kasabalis, Stavros; Kasabalis, Athanasios; Douda, Helen; Tokmakidis, Savvas; Torres-Luque, Gema
2017-06-01
The aim of the present study was to examine the relationship of vertical jump (Abalakov jump [AJ]) with anthropometric and physiological parameters in youth elite female volleyball players. Seventy-two selected volleyball players from the region of Athens (age 13.3±0.7 years, body mass 62.0±7.2 kg, height 171.5±5.7 cm, body fat 21.2±4.5%), classified into quartiles according to AJ performance (group A, 21.4-26.5 cm; group B, 26.8-29.9 cm; group C, 30.5-33.7 cm; group D, 33.8-45.9 cm), performed a series of physical fitness tests. AJ was correlated with anthropometric (age at peak height velocity [APHV]: r=0.38, Pvolleyball players that jumped the highest were those who matured later than others.
Propulsion efficiency and imposed flow fields of a copepod jump.
Jiang, Houshuo; Kiørboe, Thomas
2011-02-01
Pelagic copepods jump to relocate, to attack prey and to escape predators. However, there is a price to be paid for these jumps in terms of their energy costs and the hydrodynamic signals they generate to rheotactic predators. Using observed kinematics of various types of jumps, we computed the imposed flow fields and associated energetics of jumps by means of computational fluid dynamics simulations by modeling the copepod as a self-propelled body. The computational fluid dynamics simulation was validated by particle image velocimetry data. The flow field generated by a repositioning jump quickly evolves into two counter-rotating viscous vortex rings that are near mirror image of one another, one in the wake and one around the body of the copepod; this near symmetrical flow may provide hydrodynamic camouflage because it contains no information about the position of the copepod prey within the flow structure. The flow field associated with an escape jump sequence also includes two dominant vortex structures: one leading wake vortex generated as a result of the first jump and one around the body, but between these two vortex structures is an elongated, long-lasting flow trail with flow 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 but is caused by the rapidity and impulsiveness of the jump that allows only a low-cost viscous wake vortex to travel backwards.
Scaling of interfacial jump conditions
International Nuclear Information System (INIS)
Quezada G, S.; Vazquez R, A.; Espinosa P, G.
2015-09-01
To model the behavior of a nuclear reactor accurately is needed to have balance models that take into account the different phenomena occurring in the reactor. These balances have to be coupled together through boundary conditions. The boundary conditions have been studied and different treatments have been given to the interface. In this paper is a brief description of some of the interfacial jump conditions that have been proposed in recent years. Also, the scaling of an interfacial jump condition is proposed, for coupling the different materials that are in contact within a nuclear reactor. (Author)
Vorticity determination in a hydraulic jump by application of method ...
African Journals Online (AJOL)
The method of characteristics for solving systems of partial differential equations coupled with jump conditions is used in analysing flow downstream of a hydraulic jump instead of the normal analytical approach adopted in Hornung [1]. It is shown that the method of characteristics together with the jump conditions can ...
Quantum effects from a purely geometrical relativity theory
International Nuclear Information System (INIS)
Ellis, Homer G
2005-01-01
A purely geometrical relativity theory results from a construction that produces from three-dimensional space a happy unification of Kaluza's five-dimensional theory and Weyl's conformal theory. The theory can provide geometrical explanations for the following observed phenomena, among others: (a) visibility lifetimes of elementary particles of lengths inversely proportional to their rest masses; (b) the equality of charge magnitude among all charged particles interacting at an event; (c) the propensity of electrons in atoms to be seen in discretely spaced orbits; and (d) 'quantum jumps' between those orbits. This suggests the possibility that the theory can provide a deterministic underpinning of quantum mechanics like that provided to thermodynamics by the molecular theory of gases
Kinetic asymmetries between forward and drop jump landing tasks
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Morgana Alves de Britto
2015-12-01
Full Text Available DOI: http://dx.doi.org/10.5007/1980-0037.2015v17n6p661 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.
Serious ski jumping injuries in Norway.
Wester, K
1985-01-01
Injuries caused by ski jumping have been poorly investigated. Among approximately 2,200 licensed jumpers in Norway, there occurred at least 12 injuries with a permanent medical disability of greater than or equal to 10%. The risk of being seriously injured is approximately 5% in a 5 year period (1977 to 1981); it is higher in the age group 15 to 17 years. Seven injuries were very serious [four central nervous system (CNS) lesions, two leg amputations, and one blindness of one eye], and five were less serious (sequelae to fractures of the lower extremities). The first jump of the day is particularly dangerous, and so is the beginning and end of the season. It seems dangerous to use more than one standard heel block. Poor preparation of the jump may have contributed to the accidents. Based on the findings, several prophylactic measures are suggested.
Energy Technology Data Exchange (ETDEWEB)
Feng, Liefeng, E-mail: fengliefeng@tju.edu.cn, E-mail: lihongru@nankai.edu.cn; Yang, Xiufang; Wang, Cunda; Yao, Dongsheng [Tianjin Key Laboratory of Low Dimensional Materials Physics and Preparing Technology, Faculty of Science, Tianjin University, Tianjin 300072 (China); Li, Yang [Business and Vocational College of Hainan, Haikou 570203 (China); Li, Ding; Hu, Xiaodong [Research Center for Wide Band Gap Semiconductors, State Key Laboratory for Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University, Beijing 100871 (China); Li, Hongru, E-mail: fengliefeng@tju.edu.cn, E-mail: lihongru@nankai.edu.cn [State Key Laboratory for Medicinal Chemistry and Biology, College of Pharmacy, Nankai University, Tianjin 300071 (China)
2015-04-15
The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by I{sub th}{sup l} and I{sub th}{sup u}, as shown in Fig. 2; I{sub th}{sup l} is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; I{sub th}{sup u} is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (V{sub j}) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at I{sub th}{sup l} and I{sub th}{sup u}. The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region.
International Nuclear Information System (INIS)
Feng, Liefeng; Yang, Xiufang; Wang, Cunda; Yao, Dongsheng; Li, Yang; Li, Ding; Hu, Xiaodong; Li, Hongru
2015-01-01
The junction behavior of different narrow band-gap multi-quantum-well (MQW) laser diodes (LDs) confirmed that the jump in the junction voltage in the threshold region is a general characteristic of narrow band-gap LDs. The relative change in the 1310 nm LD is the most obvious. To analyze this sudden voltage change, the threshold region is divided into three stages by I th l and I th u , as shown in Fig. 2; I th l is the conventional threshold, and as long as the current is higher than this threshold, lasing exists and the IdV/dI-I plot drops suddenly; I th u is the steady lasing point, at which the separation of the quasi-Fermi levels of electron and holes across the active region (V j ) is suddenly pinned. Based on the evolutionary model of dissipative structure theory, the rate equations of the photons in a single-mode LD were deduced in detail at I th l and I th u . The results proved that the observed behavior of stimulated emission suddenly substituting for spontaneous emission, in a manner similar to biological evolution, must lead to a sudden increase in the injection carriers in the threshold region, which then causes the sudden increase in the junction voltage in this region
Laudner, Kevin; Evans, Daniel; Wong, Regan; Allen, Aaron; Kirsch, Tom; Long, Brian; Meister, Keith
2015-06-01
Clinicians are often challenged when making return-to-play decisions following anterior cruciate ligament reconstruction (ACL-R). Isokinetic strength and jump performance testing are common tools used to make this decision. Unfortunately, vertical jump performance standards have not been clearly established and many clinicians do not have access to isokinetic testing equipment. To establish normative jump and strength characteristics in ACL-R patients cleared by an orthopedic physician to return-to-play and to determine if relationships exist between knee isokinetic strength measurements and jump characteristics described using an electronic jump map system. Descriptive laboratory study. Thirty-three ACL-R patients who had been cleared to return to athletic competition participated in this study. Twenty-six of these ACL-R participants were also matched to 26 asymptomatic athletes based on sex, limb, height, and mass to determine isokinetic strength and jump characteristic differences between groups. Jump tests consisted of single leg vertical, double leg vertical, and a 4-jump single leg vertical jump assessed using an electronic jump mat system. Independent t-tests were used to determine differences between groups and multiple regression analyses were used to identify any relationships between jump performance and knee strength (pjump capabilities and some bilateral knee strength deficiencies compared to the matched control group. The ACL-R group also showed several moderate-to-strong positive relationships for both knee extension and flexion strength with several jump performance characteristics, such as single and double leg vertical jump height. The current results indicate that ACL-R patients present with several knee strength and vertical jump differences compared to a matched control group at the time of return-to-play. Also, ACL-R patient's performance on an electronic jump mat system is strongly related to isokinetic knee strength measures. 2b.
the Modeling of Hydraulic Jump Generated Partially on Sloping Apron
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Shaker Abdulatif Jalil
2017-12-01
Full Text Available Modeling aims to characterize system behavior and achieve simulation close as possible of the reality. The rapid energy exchange in supercritical flow to generate quiet or subcritical flow in hydraulic jump phenomenon is important in design of hydraulic structures. Experimental and numerical modeling is done on type B hydraulic jump which starts first on sloping bed and its end on horizontal bed. Four different apron slopes are used, for each one of these slopes the jump is generated on different locations by controlling the tail water depth. Modelling validation is based on 120 experimental runs which they show that there is reliability. The air volume fraction which creates in through hydraulic jump varied between 0.18 and 0.28. While the energy exchanges process take place within 6.6, 6.1, 5.8, 5.5 of the average relative jump height for apron slopes of 0.18, 0.14, 0.10, 0.07 respectively. Within the limitations of this study, mathematical prediction model for relative hydraulic jump height is suggested.The model having an acceptable coefficient of determination.
Numerical analysis of the big bounce in loop quantum cosmology
International Nuclear Information System (INIS)
Laguna, Pablo
2007-01-01
Loop quantum cosmology (LQC) homogeneous models with a massless scalar field show that the big-bang singularity can be replaced by a big quantum bounce. To gain further insight on the nature of this bounce, we study the semidiscrete loop quantum gravity Hamiltonian constraint equation from the point of view of numerical analysis. For illustration purposes, we establish a numerical analogy between the quantum bounces and reflections in finite difference discretizations of wave equations triggered by the use of nonuniform grids or, equivalently, reflections found when solving numerically wave equations with varying coefficients. We show that the bounce is closely related to the method for the temporal update of the system and demonstrate that explicit time-updates in general yield bounces. Finally, we present an example of an implicit time-update devoid of bounces and show back-in-time, deterministic evolutions that reach and partially jump over the big-bang singularity
Take-off analysis of the Olympic ski jumping competition (HS-106m).
Virmavirta, Mikko; Isolehto, Juha; Komi, Paavo; Schwameder, Hermann; Pigozzi, Fabio; Massazza, Giuseppe
2009-05-29
The take-off phase (approximately 6m) of the jumps of all athletes participating in the individual HS-106m hill ski jumping competition at the Torino Olympics was filmed with two high-speed cameras. The high altitude of the Pragelato ski jumping venue (1600m) and slight tail wind in the final jumping round were expected to affect the results of this competition. The most significant correlation with the length of the jump was found in the in-run velocity (r=0.628, pski jumping, and suggests that good jumpers simply had smaller friction between their skis and the in-run tracks and/or the aerodynamic quality of their in-run position was better. Angular velocity of the hip joint of the best jumpers was also correlated with jumping distance (r=0.651, pjumped approximately the same distance. This certainly improves the interests in ski jumping among athletes and spectators. The comparison between the take-off techniques of the best jumpers showed that even though the more marked upper body movement creates higher air resistance, it does not necessarily result in shorter jumping distance if the exposure time to high air resistance is not too long. A comparison between the first and second round jumps of the same jumpers showed that the final results in this competition were at least partly affected by the wind conditions.
Validity Study of a Jump Mat Compared to the Reference Standard Force Plate.
Rogan, Slavko; Radlinger, Lorenz; Imhasly, Caroline; Kneubuehler, Andrea; Hilfiker, Roger
2015-12-01
In the field of vertical jump diagnostics, force plates (FP) are the reference standard. Recently, despite a lack of evidence, jump mats have been used increasingly. Important factors in favor of jumping mats are their low cost and portability. This validity study compared the Haynl-Elektronik jump mat (HE jump mat) with the reference standard force plate. Ten healthy volunteers participated and each participant completed three series of five drop jumps (DJ). The parameters ground contact time (GCT) and vertical jump height (VJH) from the HE jump mat and the FP were used to evaluate the concurrent validity. The following statistical calculations were performed: Pearson's correlation (r), Bland-Altman plots (standard and for adjusted trend), and regression equations. The Bland-Altman plots suggest that the HE jump mat measures shorter contact times and higher jump heights than the FP. The trend-adjusted Bland-Altman plot shows higher mean differences and wider wing-spreads of confidence limits during longer GCT. During the VJH the mean differences and the wing-spreads of the confidence limits throughout the range present as relatively constant. The following regression equations were created, as close as possible to the true value: GCT = 5.920385 + 1.072293 × [value HE jump mat] and VJH = -1.73777 + 1.011156 × [value HE jump mat]. The HE jump mat can be recommended in relation to the validity of constraints. In this study, only a part of the quality criteria were examined. For the final recommendation it is advised to examine the HE jump mat on the other quality criteria (test-retest reliability, sensitivity change).
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
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...... 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...... differ from those implied by the futures data, which may be due to improved parameter identification....
Study of brittle crack jump rate using acoustic emission method
International Nuclear Information System (INIS)
Yasnij, P.V.; Pokrovskij, V.V.; Strizhalo, V.A.; Dobrovol'skij, Yu.V.
1987-01-01
A new peocedure is elaborated to detect brittle jumps of small length (0.1...5mm) occuring both inside the specimen and along the crack front under static and cyclic loading using the phenomena of acoustic emission (AE). Recording of the crack start and stop moments with an AE sensor as well as evaluation of the brittle crack jump length by the after-failure specimen fracture make it possible to find the mean crack propagation rate. Experimental dependences are obtained for the crack propagation rate with a brittle crack jump in steel 15Kh2MFA (σ B =1157 MPa, σ 0.2 =100 MPa) at 293 K and under cyclic loading as a function of the jump length and also as a function of the critical stress intensity factor K jc i corresponding to the crack jump
A quasi-static treatment of multiple phase jumps
International Nuclear Information System (INIS)
Englman, R; Vertesi, T
2005-01-01
A quasi-static, WKB-type treatment accounts well for the surprising phase jumps that are odd multiples of π (1 + 2n)π, found as a molecular system journeys adiabatically in a configuration coordinate plane that contains several points of degeneracies. We show that the number n in the phase jump is an integer close to |n'| that appears in the expression for the complex wavefunction amplitude valid (approximately) for times close to when the phase jump occurs: -δT + 2πθ+πn'sinδT -i[1-πn'cosδT](δT is a shifted and rescaled trajectory-time parameter and θ is a numerical fraction (<1) which depends on the adiabaticity of the motion.) The central quantity n' is local, i.e., depends on the values of the parameters in the Hamiltonian only at the beginning of the trajectory and at the instant of the phase jump
Influence of Plyometrics on Jump Capabilities in Technical and Aesthetical Sports
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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.
Coupled jump rotational dynamics in aqueous nitrate solutions.
Banerjee, Puja; Yashonath, Subramanian; Bagchi, Biman
2016-12-21
A nitrate ion (NO 3 - ) with its trigonal planar geometry and charges distributed among nitrogen and oxygen atoms can couple to the extensive hydrogen bond network of water to give rise to unique dynamical characteristics. We carry out detailed atomistic simulations and theoretical analyses to investigate these aspects and report certain interesting findings. We find that the nitrate ions in aqueous potassium nitrate solution exhibit large amplitude rotational jump motions that are coupled to the hydrogen bond rearrangement dynamics of the surrounding water molecules. The jump motion of nitrate ions bears certain similarities to the Laage-Hynes mechanism of rotational jump motions of tagged water molecules in neat liquid water. We perform a detailed atomic-level investigation of hydrogen bond rearrangement dynamics of water in aqueous KNO 3 solution to unearth two distinct mechanisms of hydrogen bond exchange that are instrumental to promote these jump motions of nitrate ions. As observed in an earlier study by Xie et al., in the first mechanism, after breaking a hydrogen bond with nitrate ion, water forms a new hydrogen bond with a water molecule, whereas the second mechanism involves just a switching of hydrogen bond between the two oxygen atoms of the same nitrate ion (W. J. Xie et al., J. Chem. Phys. 143, 224504 (2015)). The magnitude as well as nature of the reorientational jump of nitrate ion for the two mechanisms is different. In the first mechanism, nitrate ion predominantly undergoes out-of-plane rotation, while in the second mechanism, in-plane reorientation of NO 3 - is favourable. These have been deduced by computing the torque on the nitrate ion during the hydrogen bond switching event. We have defined and computed the time correlation function for coupled reorientational jump of nitrate and water and obtained the associated relaxation time which is also different for the two mechanisms. These results provide insight into the relation between the
Energy expended during horizontal jumping: investigating the effects of surface compliance
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Samuel R. L. Coward
2014-08-01
Full Text Available We present the first data on the metabolic costs of horizontal jumping in humans, using this tractable model to explore variations in energy expenditure with substrate properties, and consider these findings in light of kinematic data. Twenty-four participants jumped consistently at the rate of 1 jump per 5 s between opposing springboards separated by either a short (1.2 m or long (1.8 m gap. Springboards were either ‘firm’ or ‘compliant’. Respiratory gas exchange was measured using a back-mounted portable respiratory gas analyser to represent rate of energy expenditure, which was converted to energy expenditure per metre jumped. Video data were recorded to interpret kinematic information. Horizontal jumping was found to be between around 10 and 20 times the energy cost of cursorial locomotion per unit distance moved. There is considerable evidence from the data that jumping 1.8 m from a compliant springboard (134.9 mL O2 m−1 is less costly energetically than jumping that distance from a firm springboard (141.6 mL O2 m−1, albeit the effect size is quite small within the range of compliances tested in this study. However, there was no evidence of an effect of springboard type for jumps of 1.2 m. The kinematic analyses indicate possible explanations for these findings. Firstly, the calf muscle is likely used more, and the thigh muscles less, to take-off from a firm springboard during 1.8 m jumps, which may result in the power required to take-off being produced less efficiently. Secondly, the angle of take-off from the compliant surface during 1.8 m jumps is closer to the optimal for energetic efficiency (45°, possible due to the impulse provided by the surface as it returns stored energy during the final stages of the take-off. The theoretical effect on energy costs due to a different take-off angle for jumps of only 1.2 m is close to negligible.
Pérez-Castilla, Alejandro; García-Ramos, Amador
2018-07-01
Pérez-Castilla, A and García-Ramos, A. Evaluation of the most reliable procedure of determining jump height during the loaded countermovement jump exercise: Take-off velocity vs. flight time. J Strength Cond Res 32(7): 2025-2030, 2018-This study aimed to compare the reliability of jump height between the 2 standard procedures of analyzing force-time data (take-off velocity [TOV] and flight time [FT]) during the loaded countermovement (CMJ) exercise performed with a free-weight barbell and in a Smith machine. The jump height of 17 men (age: 22.2 ± 2.2 years, body mass: 75.2 ± 7.1 kg, and height: 177.0 ± 6.0 cm) was tested in 4 sessions (twice for each CMJ type) against external loads of 17, 30, 45, 60, and 75 kg. Jump height reliability was comparable between the TOV (coefficient of variation [CV]: 6.42 ± 2.41%) and FT (CV: 6.53 ± 2.17%) during the free-weight CMJ, but it was higher for the FT when the CMJ was performed in a Smith machine (CV: 11.34 ± 3.73% for TOV and 5.95 ± 1.12% for FT). Bland-Altman plots revealed trivial differences (≤0.27 cm) and no heteroscedasticity of the errors (R ≤ 0.09) for the jump height obtained by the TOV and FT procedures, whereas the random error between both procedures was higher for the CMJ performed in the Smith machine (2.02 cm) compared with the free-weight barbell (1.26 cm). Based on these results, we recommend the FT procedure to determine jump height during the loaded CMJ performed in a Smith machine, whereas the TOV and FT procedures provide similar reliability during the free-weight CMJ.
Validation of an inertial measurement unit for the measurement of jump count and height.
MacDonald, Kerry; Bahr, Roald; Baltich, Jennifer; Whittaker, Jackie L; Meeuwisse, Willem H
2017-05-01
To validate the use of an inertial measurement unit (IMU) for the collection of total jump count and assess the validity of an IMU for the measurement of jump height against 3-D motion analysis. Cross sectional validation study. 3D motion-capture laboratory and field based settings. Thirteen elite adolescent volleyball players. Participants performed structured drills, played a 4 set volleyball match and performed twelve counter movement jumps. Jump counts from structured drills and match play were validated against visual count from recorded video. Jump height during the counter movement jumps was validated against concurrent 3-D motion-capture data. The IMU device captured more total jumps (1032) than visual inspection (977) during match play. During structured practice, device jump count sensitivity was strong (96.8%) while specificity was perfect (100%). The IMU underestimated jump height compared to 3D motion-capture with mean differences for maximal and submaximal jumps of 2.5 cm (95%CI: 1.3 to 3.8) and 4.1 cm (3.1-5.1), respectively. The IMU offers a valid measuring tool for jump count. Although the IMU underestimates maximal and submaximal jump height, our findings demonstrate its practical utility for field-based measurement of jump load. Copyright © 2016 Elsevier Ltd. All rights reserved.
Jump Training in Youth Soccer Players: Effects of Haltere Type Handheld Loading.
Rosas, F; Ramirez-Campillo, R; Diaz, D; Abad-Colil, F; Martinez-Salazar, C; Caniuqueo, A; Cañas-Jamet, R; Loturco, I; Nakamura, F Y; McKenzie, C; Gonzalez-Rivera, J; Sanchez-Sanchez, J; Izquierdo, M
2016-12-01
The aim of this study was to compare the effects of a jump training program, with or without haltere type handheld loading, on maximal intensity exercise performance. Youth soccer players (12.1±2.2 y) were assigned to either a jump training group (JG, n=21), a jump training group plus haltere type handheld loading (LJG, n=21), or a control group following only soccer training (CG, n=21). Athletes were evaluated for maximal-intensity performance measures before and after 6 weeks of training, during an in-season training period. The CG achieved a significant change in maximal kicking velocity only (ES=0.11-0.20). Both jump training groups improved in right leg (ES=0.28-0.45) and left leg horizontal countermovement jump with arms (ES=0.32-0.47), horizontal countermovement jump with arms (ES=0.28-0.37), vertical countermovement jump with arms (ES=0.26), 20-cm drop jump reactive strength index (ES=0.20-0.37), and maximal kicking velocity (ES=0.27-0.34). Nevertheless, compared to the CG, only the LJG exhibited greater improvements in all performance tests. Therefore, haltere type handheld loading further enhances performance adaptations during jump training in youth soccer players. © Georg Thieme Verlag KG Stuttgart · New York.
Fitzgerald, Mike; Brand, Lance
2004-01-01
In this article, the authors present an egg bungee jumping activity. This activity introduces students to ways that engineers might apply calculations of failure to meet a challenge. Students are required to use common, everyday materials such as rubber bands, string, plastic bags, and eggs. They will apply technological problem solving, material…
The world price of jump and volatility risk
Driessen, J.; Maenhout, P.
2006-01-01
Jump and volatility risk are important for understanding equity returns, option pricing and asset allocation. This paper is the first to study international integration of markets for jump and volatility risk, using data on index options for each of the three main global markets: US S&P 500 index
Vertical and Horizontal Jump Capacity in International Cerebral Palsy Football Players.
Reina, Raúl; Iturricastillo, Aitor; Sabido, Rafael; Campayo-Piernas, Maria; Yanci, Javier
2018-05-01
To evaluate the reliability and validity of vertical and horizontal jump tests in football players with cerebral palsy (FPCP) and to analyze the jump performance differences between current International Federation for Cerebral Palsy Football functional classes (ie, FT5-FT8). A total of 132 international parafootballers (25.8 [6.7] y; 70.0 [9.1] kg; 175.7 [7.3] cm; 22.8 [2.8] kg·m -2 ; and 10.7 [7.5] y training experience) participated in the study. The participants were classified according to the International Federation for Cerebral Palsy Football classification rules, and a group of 39 players without cerebral palsy was included in the study as a control group. Football players' vertical and horizontal jump performance was assessed. All the tests showed good to excellent relative intrasession reliability scores, both in FPCP and in the control group (intraclass correlation = .78-.97, SEM jump, standing broad jump, 4 bounds for distance, and triple hop for distance dominant leg and nondominant leg. The control group performed higher/farther jumps with regard to all the FPCP classes, obtaining significant differences and moderate to large effect sizes (ESs) (.85 jump tests than players in the lower classes (ES = moderate to large, P jump tests performed in this study could be applied to the classification procedures and protocols for FPCP.
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 exit-time problem for a Markov jump process
Burch, N.; D'Elia, M.; Lehoucq, R. B.
2014-12-01
The purpose of this paper is to consider the exit-time problem for a finite-range Markov jump process, i.e, the distance the particle can jump is bounded independent of its location. Such jump diffusions are expedient models for anomalous transport exhibiting super-diffusion or nonstandard normal diffusion. We refer to the associated deterministic equation as a volume-constrained nonlocal diffusion equation. The volume constraint is the nonlocal analogue of a boundary condition necessary to demonstrate that the nonlocal diffusion equation is well-posed and is consistent with the jump process. A critical aspect of the analysis is a variational formulation and a recently developed nonlocal vector calculus. This calculus allows us to pose nonlocal backward and forward Kolmogorov equations, the former equation granting the various moments of the exit-time distribution.
Role of the hamstrings in human vertical jumping
Bobbert, Maarten F.
1996-01-01
In some human subjects performing maximum-height squat jumps, the EMG-pattern of semitendinosus is bi-phasic and that of biceps femoris is mono-phasic. The purpose of this study was to investigate the roles of biceps femoris and semitendinosus in squat jumping, and to explain why they are different.
Universal Earthquake-Occurrence Jumps, Correlations with Time, and Anomalous Diffusion
International Nuclear Information System (INIS)
Corral, Alvaro
2006-01-01
Spatiotemporal properties of seismicity are investigated for a worldwide (WW) catalog and for southern California in the stationary case (SC), showing a nearly universal scaling behavior. Distributions of distances between consecutive earthquakes (jumps) are magnitude independent and show two power-law regimes, separated by jump values about 200 (WW) and 15 km (SC). Distributions of waiting times conditioned to the value of jumps show that both variables are correlated, in general, but turn out to be independent when only short or long jumps are considered. Finally, diffusion profiles are found to be independent on the magnitude, contrary to what the waiting-time distributions suggest
Ball, Stephen; Cohen, Ann; Meyer, Margaret
2012-01-01
Jump Into Action (JIA) is a school-based team-taught program to help fifth-grade students make healthy food choices and be more active. The JIA team (physical education teacher, classroom teacher, school nurse, and parent) work together to provide a supportive environment as students set goals to improve food choices and increase activity.…
Filtering of a Markov Jump Process with Counting Observations
International Nuclear Information System (INIS)
Ceci, C.; Gerardi, A.
2000-01-01
This paper concerns the filtering of an R d -valued Markov pure jump process when only the total number of jumps are observed. Strong and weak uniqueness for the solutions of the filtering equations are discussed
An algorithm to remove fringe jumps and its application to microwave reflectometry
International Nuclear Information System (INIS)
Ejiri, A.; Kawahata, K.; Shinohara, K.
1997-01-01
In some plasma discharges, the phase measured by microwave reflectometry has many fringe (2π radians) jumps. A new algorithm to detect and remove fringe jumps has been developed, and applied to the data in the JIPP TII-U tokamak. Using this algorithm, quantitative properties of fringe jumps, and their effects on the analysis of phase fluctuations are investigated. It was found that the occurrence of fringe jumps obeys a Poisson process, and the time scale of jumps is distributed over a wide range. Fringe jumps affect mainly the low-frequency components of phase fluctuations. Comparison of the phase corrected by the algorithm and the phase calculated from the time smoothed signals indicates that time smoothing (or frequency filtering) is an effective way to obtain information concerning the macroscopic density profile. Fringe jump and phase runaway can be phenomenologically explained by the distribution of the complex amplitude of the reflected wave. (author)
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.
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.
Salticid predation as one potential driving force of ant mimicry in jumping spiders
Huang, Jin-Nan; Cheng, Ren-Chung; Li, Daiqin; Tso, I-Min
2011-01-01
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. PMID:20961898
Validity of a jump training apparatus using Wii Balance Board.
Yamamoto, Keizo; Matsuzawa, Mamoru
2013-05-01
The dynamic quantification of jump ability is useful for sports performance evaluation. We developed a force measurement system using the Wii Balance Board (WBB). This study was conducted to validate the system in comparison with a laboratory-grade force plate (FP). For a static validation, weights of 10-180kg were put progressively on the WBB put on the FP. The vertical component of the ground reaction force (vGRF) was measured using both devices and compared. For the dynamic validation, 10 subjects without lower limb pathology participated in the study and performed vertical jumping twice on the WBB on the FP. The range of analysis was set from the landing after the first jump to taking off of the second jump. The peak values during the landing phase and jumping phase were obtained and the force-time integral (force impulse) was measured. The relations of the values measured using each device were compared using Pearson's correlation coefficient test and Bland-Altman plots (BAP). Significant correlation (P<.01, r=.99) was found between the values of both devices in the static and the dynamic test. Examination of the BAP revealed a proportion error in the landing phase and showed no relation in the jumping phase between the difference and the mean in the dynamic test. The WBB detects the vGRF in the jumping phase with high precision. Copyright © 2012 Elsevier B.V. All rights reserved.
Forces exerted by jumping children: A pilot study
Moes, C.C.M.; Bakker, H.E.
1998-01-01
This article reports on a pilot study of the loads exerted vertically by children when jumping. The subjects of the study were 17 children, aged from two to twelve years. Measurements were made using video recordings and a force-plate. The influence of the stiffness of the base and of jumping with
Immediate effects of different types of stretching exercises on badminton jump smash.
Jang, Hwi S; Kim, Daeho; Park, Jihong
2018-01-01
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 point 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: F(2,75)=1.19, P=0.31; static stretching: 22.1%, Pjump-smashed shuttlecocks (type main effect: F(2,75)=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: F(2,75)=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.
Nordic ski jumping fatalities in the United States: a 50-year summary.
Wright, J R
1988-06-01
Nordic ski-jumping fatalities are rare events. Six jumping fatalities have occurred in the United States during the past 50 years. The fatality rate for nordic ski jumping, estimated to be roughly 12 fatalities/100,000 participants annually, appears to be within the range of fatality rates for other "risky" outdoor sports. Cervical fractures appear to be the most frequent fatal ski-jumping injury.
Marián, Vanderka; Katarína, Longová; Dávid, Olasz; Matúš, Krčmár; Simon, Walker
2016-01-01
The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax) and rate of force development over 100ms (RFD100), countermovement jump (CMJ) and squat jump (SJ) height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg) were divided into experimental (EXP; n = 36) and control (CON, n = 32) groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions). Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, psquats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term. Key points Jump squat exercise is one of many exercises to develop explosive strength that has been the focus of several researches, while the load used during the training seem to be an important factor that affects training outcomes. Experimental group improved performance in all assessed parameters, such as Fmax, RFD100, CMJ, SJ and 50 m sprint time. However, improvements in CMJ and SJ were recorded after the entire power training period and thereafter plateau occurred. The portable FitroDyne could serve as a valuable device to individualize the load that maximizes mean power output and visual feedback can be provided to athletes during the training. PMID:27803628
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......For risk management traders in the electricity market are mainly interested in the risk of negative (drops) or of positive (spikes) price jumps, i.e. the sellers face the risk of negative price jumps while the buyers face the risk of positive price jumps. Understanding the mechanism that drive...
Self-jumping Mechanism of Melting Frost on Superhydrophobic Surfaces.
Liu, Xiaolin; Chen, Huawei; Zhao, Zehui; Wang, Yamei; Liu, Hong; Zhang, Deyuan
2017-11-07
Frost accretion on surfaces may cause severe problems and the high-efficiency defrosting methods are still urgently needed in many application fields like heat transfer, optical and electric power system, etc. In this study, a nano-needle superhydrophobic surface is prepared and the frosting/defrosting experiments are conducted on it. Three steps are found in the defrosting process: melting frost shrinking and splitting, instantaneous self-triggered deforming followed by deformation-induced movements (namely, in-situ shaking, rotating, rolling, and self-jumping). The self-jumping performance of the melting frost is extremely fascinating and worth studying due to its capability of evidently shortening the defrosting process and reducing (even avoiding) residual droplets after defrosting. The study on the melting frost self-jumping phenomena demonstrates that the kinetic energy transformed from instantaneous superficial area change in self-triggered deforming step is the intrinsic reason for various melting frost self-propelled movements, and when the transformed energy reaches a certain amount, the self-jumping phenomena occur. And some facilitating conditions for melting frost self-jumping phenomena are also discussed. This work will provide an efficient way for defrosting or an inspiration for further research on defrosting.
Approaching stationarity: competition between long jumps and long waiting times
International Nuclear Information System (INIS)
Dybiec, Bartłomiej
2010-01-01
Within the continuous-time random walk (CTRW) scenarios, properties of the overall motion are determined by the waiting time and the jump length distributions. In the decoupled case, with power-law distributed waiting times and jump lengths, the CTRW scenario is asymptotically described by the double (space and time) fractional Fokker–Planck equation. Properties of a system described by such an equation are determined by the subdiffusion parameter and the jump length exponent. Nevertheless, the stationary state is determined solely by the jump length distribution and the potential. The waiting time distribution determines only the rate of convergence to the stationary state. Here, we inspect the competition between long waiting times and long jumps and how this competition is reflected in the way in which a stationary state is reached. In particular, we show that the distance between a time-dependent and a stationary solution changes in time as a double power law
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…
Walsh, Mark S; Waters, Jeff A; Böhm, Harald; Potteiger, Jeff A
2007-08-01
The purposes of this study are to examine gender differences in the contribution of the arm swing to jump height in men and women basketball players and to examine the role of upper-body strength in the contribution of arm swing to jump height. National Collegiate Athletic Association Division I basketball players (men n = 13, women n = 12) performed 4 jumping movements: squat jumps with hands on hips (SNA) and with arm swings (SA) and countermovement jumps with hands on hips and with arm swings (CMA). Differences were found between the jump heights of men and women. Use of the arms increased the jump height of men more than women. Compared with the SNA, the SA allowed an increase of 7 cm (23%) for men and 4 cm (17%) for women. The CMA allowed for an increase of 10 cm (30%) for men and 6 cm (24%) for women. General upper-body strength measures did not correlate strongly with the effect of arms on jumping, but peak power did. As in previous studies, peak power had a high correlation with jumping performance. These results show that the arm swing contributes significantly to jump performance in both men and women basketball players and that strength training for jumping should focus on power production and lifting exercises that are jump specific.
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...
Hydraulic jumps in ''viscous'' accretion disks
International Nuclear Information System (INIS)
Michel, F.C.
1984-01-01
We propose that the dissipative process necessary for rapid accretion disk evolution is driven by hydraulic jump waves on the surface of the disk. These waves are excited by the asymmetric nature of the central rotator (e.g., neutron star magnetosphere) and spiral out into the disk to form a pattern corotating with the central object. Disk matter in turn is slowed slightly at each encounter with the jump and spirals inward. In this process, the disk is heated by true turbulence produced in the jumps. Additional effects, such as a systematic misalignment of the magnetic moment of the neutron star until it is nearly orthogonal, and systematic distortion of the magnetosphere in such a way as to form an even more asymmetric central ''paddle wheel'' may enhance the interaction with inflowing matter. The application to X-ray sources corresponds to the ''slow'' solutions of Ghosh and Lamb, and therefore to rms magnetic fields of about 4 x 10 10 gauss. Analogous phenomena have been proposed to act in the formation of galactic spiral structure
McBride, Jeffrey M; Kirby, Tyler J; Haines, Tracie L; Skinner, Jared
2010-12-01
The purpose of the current investigation was to determine the relationship between relative net vertical impulse (net vertical impulse (VI)) and jump height in the jump squat (JS) going to different squat depths and utilizing various loads. Ten males with two years of jumping experience participated in this investigation (Age: 21.8 ± 1.9 y; Height: 176.9 ± 5.2 cm; Body Mass: 79.0 ± 7.1 kg, 1RM: 131.8 ± 29.5 kg, 1RM/BM: 1.66 ± 0.27). Subjects performed a series of static jumps (SJS) and countermovement jumps (CMJJS) with various loads (Body Mass, 20% of 1RM, 40% of 1RM) in a randomized fashion to a depth of 0.15, 0.30, 0.45, 0.60, and 0.75 m and a self-selected depth. During the concentric phase of each JS, peak force (PF), peak power (PP), jump height (JH) and relative VI were recorded and analyzed. Increasing squat depth corresponded to a decrease in PF and an increase in JH, relative VI for both SJS and CMJJS during all loads. Across all squat depths and loading conditions relative VI was statistically significantly correlated to JH in the SJS (r = .8956, P squat depths and loading conditions PF was statistically nonsignificantly correlated to JH in the SJS (r = -0.1010, P = .2095, power = 0.2401) and CMJJS (r = -0.0594, P = .4527, power = 0.1131). Across all squat depths and loading conditions peak power (PP) was significantly correlated with JH during both the SJS (r = .6605, P squat depths. Results indicate that relative VI and PP can be used to predict JS performance, regardless of squat depth and loading condition. However, relative VI may be the best predictor of JS performance with PF being the worst predictor of JS performance.
The effect of increasing strength and approach velocity on triple jump performance.
Allen, Sam J; Yeadon, M R Fred; King, Mark A
2016-12-08
The triple jump is an athletic event comprising three phases in which the optimal phase ratio (the proportion of each phase to the total distance jumped) is unknown. This study used a planar whole body torque-driven computer simulation model of the ground contact parts of all three phases of the triple jump to investigate the effect of strength and approach velocity on optimal performance. The strength and approach velocity of the simulation model were each increased by up to 30% in 10% increments from baseline data collected from a national standard triple jumper. Increasing strength always resulted in an increased overall jump distance. Increasing approach velocity also typically resulted in an increased overall jump distance but there was a point past which increasing approach velocity without increasing strength did not lead to an increase in overall jump distance. Increasing both strength and approach velocity by 10%, 20%, and 30% led to roughly equivalent increases in overall jump distances. Distances ranged from 14.05m with baseline strength and approach velocity, up to 18.49m with 30% increases in both. Optimal phase ratios were either hop-dominated or balanced, and typically became more balanced when the strength of the model was increased by a greater percentage than its approach velocity. The range of triple jump distances that resulted from the optimisation process suggests that strength and approach velocity are of great importance for triple jump performance. Copyright © 2016 Elsevier Ltd. All rights reserved.
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...... participated in the study. The training was supervised and augmented feedback on performance was used to ensure maximal training intensity. The drop jumps were performed with minimal contact time and maximal jumping height. Assessment of performance during training showed effects of motor learning. Before...... and after the training intervention maximal isometric muscle strength, the biomechanics, muscle activity pattern of the lower extremities and the soleus H-reflex and V-wave during drop jumping were measured. Maximal jump height and performance index (PI) defined as jumping height divided by contact time...
Directory of Open Access Journals (Sweden)
H. Makaruk
2014-07-01
Full Text Available The aim of this study was to examine the chronic effects of single and repeated jumps training on vertical landing force (VGRF and jump height in untrained men. The VGRF and jump height were compared after a six-week plyometric training programme containing single and repeated jumps, together with two additional parameters: landing time (LT and range of the knee flexion during landing (KF. Thirty-six untrained physical education students with a plyometric training background were randomly assigned to a single jump group (SJG, n =12, repeated jumps group (RJG, n =12, and control group (CON, n =12. The SJG performed only single jumps, the RJG executed repeated (consecutive jumps, whereas the CON did not perform any exercises at all. A countermovement jump (CMJ, repeated countermovement jumps (RCMJ, and a drop jump (DJ were tested before and after the training. Only the RJG showed a significantly reduced VGRF (p<0.05 in all tests. Both plyometric groups significantly improved (p<0.05 their jump height in all tests. The LT was significantly greater in the RJG, compared to the SJG, in all tests. The KF was also significantly (p<0.05 greater in the RJG than in the SJG for CMJ and RCMJ. The results suggest that repeated jumps are beneficial for simultaneous landing force reduction and jumping performance enhancement.
A Jump-Diffusion Model with Stochastic Volatility and Durations
DEFF Research Database (Denmark)
Wei, Wei; Pelletier, Denis
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...
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...
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.
Aerial Rotation Effects on Vertical Jump Performance Among Highly Skilled Collegiate Soccer Players.
Barker, Leland A; Harry, John R; Dufek, Janet S; Mercer, John A
2017-04-01
Barker, LA, Harry, JR, Dufek, JS, and Mercer, JA. Aerial rotation effects on vertical jump performance among highly skilled collegiate soccer players. J Strength Cond Res 31(4): 932-938, 2017-In soccer matches, jumps involving rotations occur when attempting to head the ball for a shot or pass from set pieces, such as corner kicks, goal kicks, and lob passes. However, the 3-dimensional ground reaction forces used to perform rotational jumping tasks are currently unknown. Therefore, the purpose of this study was to compare bilateral, 3-dimensional, and ground reaction forces of a standard countermovement jump (CMJ0) with those of a countermovement jump with a 180° rotation (CMJ180) among Division-1 soccer players. Twenty-four participants from the soccer team of the University of Nevada performed 3 trials of CMJ0 and CMJ180. Dependent variables included jump height, downward and upward phase times, vertical (Fz) peak force and net impulse relative to mass, and medial-lateral and anterior-posterior force couple values. Statistical significance was set a priori at α = 0.05. CMJ180 reduced jump height, increased the anterior-posterior force couple in the downward and upward phases, and increased upward peak Fz (p ≤ 0.05). All other variables were not significantly different between groups (p > 0.05). However, we did recognize that downward peak Fz trended lower in the CMJ0 condition (p = 0.059), and upward net impulse trended higher in the CMJ0 condition (p = 0.071). It was concluded that jump height was reduced during the rotational jumping task, and rotation occurred primarily via AP ground reaction forces through the entire countermovement jump. Coaches and athletes may consider additional rotational jumping in their training programs to mediate performance decrements during rotational jump tasks.
GENDER DIFFERENCES AND BIOMECHANICS IN THE 3000M STEEPLECHASE WATER JUMP
Directory of Open Access Journals (Sweden)
Kassi R. Andersen
2008-06-01
Full Text Available Since 1996, women have been competing in the 3000m steeplechase race internationally. Whenever women and men both compete in similar events with different equipment (the barriers are lower for women consideration should be given as to how techniques should be coached differently. This study investigated the differences in water-jump technique between men and women after accounting for differences in running speed and which techniques led to maintenance of race pace through the water-jump. Eighteen men and 18 women were filmed at two major track and field meets during the 2004 season. Peak Motus 8.2 was used to digitize all seven jumps from each athlete. Various characteristics of water-jump technique were measured or calculated and compared using two multiple linear regressions (one for men and one for women to determine which characteristics led to maintaining race pace speeds through the water jump obstacle. Repeated measures ANOVA was used to determine any differences between men and women in the measured characteristics of technique.Velocity through the jump divided by race pace was predicted very well by approach velocity and landing distance for men and women. Other characteristics of the movement were non-significant. Differences between genders were found in: approach velocity, take-off distance, landing distance, push-off angle, velocity through jump, and exit velocity. Men and women steeplechasers must focus on approach velocity and landing distance to complete the water-jump close to their race pace. Coaches need to consider many characteristics of technique that differ between men and women
Ankle taping does not impair performance in jump or balance tests.
Abián-Vicén, Javier; Alegre, Luis M; Fernández-Rodríguez, J Manuel; Lara, Amador J; Meana, Marta; Aguado, Xavier
2008-01-01
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. Key pointsAnkle taping has no influence on balance performance.Ankle taping does not impair performance during the push-off phase of the jump.Ankle taping could increase the risk of injury during landings by increasing peak forces.
International Nuclear Information System (INIS)
Budak, G.; Polat, R.
2004-01-01
The X-ray absorption jump factor and jump ratio of Gd, Dy, Ho and Er were measured with a Si(Li) detector by attenuation, with Gd, Dy, Ho and Er foil, a Compton peak produced by the scattering of the 59.5 keV Am-241 Gamma rays. Al was chosen as secondary exciter. The experimental absorption jump factors and jump ratios are compared with the theoretical estimates of WinXcom (Radiat. Phys. Chem. 60 (2001) 23), McMaster (Compilation of X-ray cross sections UCRL-50174, 1969; Sec. II. Rev. I), Broll (X-ray Spectrom 15 (1986) 271), Hubbel and Seltzer (NISTIR (1995) 5632) and Budak (Radiat. Meas. accepted for publication). The present results constitute the first measurement for this combination of energy and elements, and good agreement is obtained between experiment and theory
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 (pJump 1 was fixated on significantly earlier and more frequently than jump 2 or 3 (pjump 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. PMID:24846055
A multiplicity jump trigger using silicon planes
International Nuclear Information System (INIS)
Alexopoulos, T.; Erwin, A.R.
1993-01-01
Since silicon tracking planes are already present in a B decay experiment, it is an attractive idea to use these as part of a multiplicity jump detector. Two average B decays would produce a multiplicity jump of around 10 in the final state. Such a trigger has been tried for a fixed target Charm experiment with disappointing success. The failure was attributed to the difficulty in adequately controlling the gains of a large number of microstrip amplifies
Effect of a neuromuscular training program on the kinetics and kinematics of jumping tasks.
Chappell, Jonathan D; Limpisvasti, Orr
2008-06-01
Altered motor control strategies are a proposed cause of the female athlete's increased risk for noncontact anterior cruciate ligament injury. Injury prevention programs have shown promising results in decreasing the incidence of anterior cruciate ligament injury. To evaluate the effect of the Kerlan-Jobe Orthopaedic Clinic Modified Neuromuscular Training Program on the biomechanics of select jumping tasks in the female collegiate athlete. Controlled laboratory study. Thirty female National Collegiate Athletic Association Division I soccer and basketball players performed vertical jump, hopping tests, and 2 jumping tasks (drop jump and stop jump). All subjects completed a 6-week neuromuscular training program with core strengthening and plyometric training. Three-dimensional motion analysis and force plate data were used to compare the kinetics and kinematics of jumping tasks before and after training. Dynamic knee valgus moment during the stance phase of stop jump tasks decreased after completion of the neuromuscular training program (P = .04), but differences were not observed for the drop jump. Initial knee flexion (P = .003) and maximum knee flexion (P = .006) angles increased during the stance phase of drop jumps after training, but differences were not observed for the stop jump. The athletes showed improved performance in vertical jump (P training program improved select athletic performance measures and changed movement patterns during jumping tasks in the subject population. The use of this neuromuscular training program could potentially modify the collegiate athlete's motion strategies, improve performance, and lower the athlete's risk for injury.
I Gusti Ngurah Agung Cahya Prananta; N. Adiputra; I P G Adiatmika
2015-01-01
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...
Asymptotic inference for jump diffusions with state-dependent intensity
Becheri, Gaia; Drost, Feico; Werker, Bas
2016-01-01
We establish the local asymptotic normality property for a class of ergodic parametric jump-diffusion processes with state-dependent intensity and known volatility function sampled at high frequency. We prove that the inference problem about the drift and jump parameters is adaptive with respect to
Variability of Jump Kinetics Related to Training Load in Elite Female Basketball
Jan Legg; David B. Pyne; Stuart Semple; Nick Ball
2017-01-01
The purpose of this study was to quantify changes in jump performance and variability in elite female basketballers. Junior and senior female representative basketball players (n = 10) aged 18 ± 2 years participated in this study. Countermovement jump (CMJ) data was collected with a Gymaware™ optical encoder at pre-, mid-, and post-season time points across 10 weeks. Jump performance was maintained across the course of the full season (from pre to post). Concentric peak velocity, jump height,...
Asymptotic Behaviour and Extinction of Delay Lotka-Volterra Model with Jump-Diffusion
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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.
ACUTE EFFECTS OF A RESISTED DYNAMIC WARM-UP PROTOCOL ON JUMPING PERFORMANCE
Cilli, M; Yildiz, S; Saglam, T; Camur, MH
2014-01-01
This study aimed to investigate the kinematic and kinetic changes when resistance is applied in horizontal and vertical directions, produced by using different percentages of body weight, caused by jumping movements during a dynamic warm-up. The group of subjects consisted of 35 voluntary male athletes (19 basketball and 16 volleyball players; age: 23.4 ± 1.4 years, training experience: 9.6 ± 2.7 years; height: 177.2 ± 5.7 cm, body weight: 69.9 ± 6.9 kg) studying Physical Education, who had a jump training background and who were training for 2 hours, on 4 days in a week. A dynamic warm-up protocol containing seven specific resistance movements with specific resistance corresponding to different percentages of body weight (2%, 4%, 6%, 8%, 10%) was applied randomly on non consecutive days. Effects of different warm-up protocols were assessed by pre-/post- exercise changes in jump height in the countermovement jump (CMJ) and the squat jump (SJ) measured using a force platform and changes in hip and knee joint angles at the end of the eccentric phase measured using a video camera. A significant increase in jump height was observed in the dynamic resistance warm-up conducted with different percentages of body weight (p 0.05). In jump movements before and after the warm-up, while no significant difference between the vertical ground reaction forces applied by athletes was observed (p > 0.05), in some cases of resistance, a significant reduction was observed in hip and knee joint angles (p jumping movements, as well as an increase in jump height values. As a result, dynamic warm-up exercises could be applicable in cases of resistance corresponding to 6-10% of body weight applied in horizontal and vertical directions in order to increase the jump performance acutely. PMID:25435670
Transition-energy crossing with a γt-jump
International Nuclear Information System (INIS)
Wei, Jie; Peggs, S.
1994-01-01
Expressions for the minimum size and speed of a transition-energy (γ t -) jump needed to diminish the chromatic non-linear effect, the self-field mismatch, and the microwave instabilities in the Relativistic Heavy Ion Collider (RHIC) are obtained. A γ t -jump of 0.8 units is needed to be performed within 60 ms in order to achieve a ''clean'' transition crossing
ANKLE TAPING DOES NOT IMPAIR PERFORMANCE IN JUMP OR BALANCE TESTS
Directory of Open Access Journals (Sweden)
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
CONNECTION OF FUNCTIONAL ABILITIES WITH JUMPING AND THROWING ATHLETIC DISCIPLINES
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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.
Long multiplication by instruction sequences with backward jump instructions
Bergstra, J.A.; Middelburg, C.A.
2013-01-01
For each function on bit strings, its restriction to bit strings of any given length can be computed by a finite instruction sequence that contains only instructions to set and get the content of Boolean registers, forward jump instructions, and a termination instruction. Backward jump instructions
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 (pjump. Only two more variables, the angle between the upper body and the horizontal plane (TV=53.69%), and the angle between left ski 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.
Discharge regimes and density jumps in a helicon plasma source
International Nuclear Information System (INIS)
Shinohara, S.; Yonekura, K.
1999-01-01
A high density plasma source using a helicon wave is becoming very attractive in plasma processing and confinement devices. In the previous work, the characteristics of this wave and plasma performance with diameters of 5 and 45 cm have been studied, and the helicon wave was only observed after the density jump. Recently, density jumps from the low to high electron densities with a level of 10 13 cm -3 were investigated by changing the antenna wavenumber spectrum, and the obtained results were compared with the inductively coupled plasma (ICP). However, the mechanisms of density jumps and plasma production are still open questions to be answered. Here, the authors try to investigate the discharge regimes and density jumps in a helicon plasma source, by changing the antenna wavenumber spectrum. For he case of the parallel current directions in the antenna, where the low wavenumber spectrum part is large, the density jump was observed with the low RF input power of P in < 300 W regardless of the magnetic field. On the other hand, for the case of the opposite directions, where the low wavenumber spectrum part is small, the threshold power to obtain the jump became high with the increase in the magnetic field. This can be understood from the dispersion relation of the helicon wave. The wave structures and the dispersion relations in the discharge modes will be also shown
Jump diffusion models and the evolution of financial prices
International Nuclear Information System (INIS)
Figueiredo, Annibal; Castro, Marcio T. de; Silva, Sergio da; Gleria, Iram
2011-01-01
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. -- 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.
Can, Ibrahim
2018-01-01
The purpose of this study was to investigate the relationship between sprint and jump performance with velocity parameters in the loaded-squat jump exercise (SQ[subscript Loaded]). In accordance with this purpose, a total of 13 athletes competing in martial sports have participated in this study voluntarily. In this study, sprint tests, vertical…
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.
CLIMATIC JUMP IN THE POLAR REGION (I)
ヤマモト, リョウザブロウ; イワシマ, タツヤ; ホシアイ, マコト; Ryozaburo, YAMAMOTO; Tatsuya, IWASHIMA; Makoto, HOSHIAI
1987-01-01
From the analysis of the climatic elements over Japan, we can detect the "climatic jumps" around the years 1920 and 1950,which is a new concept in the climatic diagnosis proposed by the present authors (R. YAMAMOTO et al. : J. Meteorol. Soc. Jpn., 63,1157,1985,64,273,1986). Taking account of several results which show the simultaneous occurrence of the climatic jumps of the surface air temperature, precipitation, etc., in the other regions by the other investigators, we may infer the "climati...
Potentiation: Effect of Ballistic and Heavy Exercise on Vertical Jump Performance.
Hester, Garrett M; Pope, Zachary K; Sellers, John H; Thiele, Ryan M; DeFreitas, Jason M
2017-03-01
Hester, GM, Pope, ZK, Sellers, JH, Thiele, RM, and DeFreitas, JM. Potentiation: Effect of ballistic and heavy exercise on vertical jump performance. J Strength Cond Res 31(3): 660-666, 2017-The purpose of this study was to compare the acute effects of heavy and ballistic conditioning protocols on vertical jump performance in resistance-trained men. Fourteen resistance-trained men (mean ± SD: age = 22 ± 2.1 years, body mass = 86.29 ± 9.95 kg, and height = 175.39 ± 9.34 cm) with an average relative full squat of 2.02 ± 0.28 times their body mass participated in this study. In randomized, counterbalanced order, subjects performed two countermovement vertical jumps before and 1, 3, 5, and 10 minutes after either performing 10 rapid jump squats or 5 heavy back squats. The back squat protocol consisted of 5 repetitions at 80% one repetition maximum (1RM), whereas the jump squat protocol consisted of 10 repetitions at 20% 1RM. Peak jump height (in centimeters) using a jump mat, along with power output (in Watts) and velocity (in meters per second) through a linear transducer, was recorded for each time interval. There was no significant condition × time interaction for any of the dependent variables (p = 0.066-0.127). In addition, there was no main effect for condition for any of the dependent variables (p = 0.457-0.899). Neither the ballistic nor heavy protocol used in this study enhanced vertical jump performance at any recovery interval. The use of these protocols in resistance-trained men to produce postactivation potentiation is not recommended.
Acute effects of heavy-load squats on consecutive squat jump performance.
Weber, Kurt R; Brown, Lee E; Coburn, Jared W; Zinder, Steven M
2008-05-01
Postactivation potentiation (PAP) and complex training have generated interest within the strength and conditioning community in recent years, but much of the research to date has produced confounding results. The purpose of this study was to observe the acute effects of a heavy-load back squat [85% 1 repetition maximum (1RM)] condition on consecutive squat jump performance. Twelve in-season Division I male track-and-field athletes participated in two randomized testing conditions: a five-repetition back squat at 85% 1RM (BS) and a five-repetition squat jump (SJ). The BS condition consisted of seven consecutive squat jumps (BS-PRE), followed by five repetitions of the BS at 85% 1RM, followed by another set of seven consecutive squat jumps (BS-POST). The SJ condition was exactly the same as the BS condition except that five consecutive SJs replaced the five BSs, with 3 minutes' rest between each set. BS-PRE, BS-POST, SJ-PRE, and SJ-POST were analyzed and compared for mean and peak jump height, as well as mean and peak ground reaction force (GRF). The BS condition's mean and peak jump height and peak GRF increased 5.8% +/- 4.8%, 4.7% +/- 4.8%, and 4.6% +/- 7.4%, respectively, whereas the SJ condition's mean and peak jump height and peak GRF decreased 2.7% +/- 5.0%, 4.0% +/- 4.9%, and 1.3% +/- 7.5%, respectively. The results indicate that performing a heavy-load back squat before a set of consecutive SJs may enhance acute performance in average and peak jump height, as well as peak GRF.
Kinetic Compensations due to Chronic Ankle Instability during Landing and Jumping.
Kim, Hyunsoo; Son, S Jun; Seeley, Matthew K; Hopkins, J Ty
2018-02-01
Skeletal muscles absorb and transfer kinetic energy during landing and jumping, which are common requirements of various forms of physical activity. Chronic ankle instability (CAI) is associated with impaired neuromuscular control and dynamic stability of the lower extremity. Little is known regarding an intralimb, lower-extremity joint coordination of kinetics during landing and jumping for CAI patients. We investigated the effect of CAI on lower-extremity joint stiffness and kinetic and energetic patterns across the ground contact phase of landing and jumping. One hundred CAI patients and 100 matched able-bodied controls performed five trials of a landing and jumping task (a maximal vertical forward jump, landing on a force plate with the test leg only, and immediate lateral jump toward the contralateral side). Functional analyses of variance and independent t-tests were used to evaluate between-group differences for lower-extremity net internal joint moment, power, and stiffness throughout the entire ground contact phase of landing and jumping. Relative to the control group, the CAI group revealed (i) reduced plantarflexion and knee extension and increased hip extension moments; (ii) reduced ankle and knee eccentric and concentric power, and increased hip eccentric and concentric power, and (iii) reduced ankle and knee joint stiffness and increased hip joint stiffness during the task. CAI patients seemed to use a hip-dominant strategy by increasing the hip extension moment, stiffness, and eccentric and concentric power during landing and jumping. This apparent compensation may be due to decreased capabilities to produce sufficient joint moment, stiffness, and power at the ankle and knee. These differences might have injury risk and performance implications.
Bahr, Martin A; Bahr, Roald
2014-09-01
Male sex, total training volume (number of hours per week) and match exposure (number of sets played per week) are risk factors for jumper's knee among young elite volleyball players. However, it is not known whether jump frequency differs among players on the same squad. To examine interindividual and sex differences in jump frequency during training and matches in young elite volleyball players. Observational study. Norwegian elite volleyball boarding school training programme. Student-athletes (26 boys and 18 girls, 16-18 years). Individual jump counts were recorded based on visual analysis of video recordings obtained from 1 week of volleyball training (9 training sessions for boys and 10 for girls, 14.1 h and 17.8 h of training, respectively) and 10 matches (5.9 h for boys (16 sets) and 7.7 h for girls (21 sets). A total of 11,943 jumps were recorded, 4138 during matches and 7805 during training. As training attendance and jump frequency varied substantially between players, the total exposure in training ranged from 50 to 666 jumps/week among boys and from 11 to 251 jumps/week among girls. On average, this corresponded to 35.7 jumps/h for boys and 13.7 jumps/h for girls (Student t test, p=0.002). Total jump exposure during matches ranged between 1 and 339 jumps among boys and between 0 and 379 jumps among girls, corresponding to an average jump frequency of 62.2 jumps/h for boys and 41.9 jumps/h for girls (Student t test, pvolleyball players. Total jump volume may represent a more important risk factor for jumper's knee than total training volume, warranting further research attention. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
THE EFFECTS OF SIXWEEKS PROGRAM OF PLYOMETRIC TRENING ON VOLLEYBALL JUMPING
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Vladan Milić
2008-08-01
Full Text Available With goal to examine effects of plyometric training program on development of jumping strength for volleyball players, it was organized an experimental research on pattern of 23 volleyball players from cadet team and 23 students from high-school. Guided by general principles for plyometric training, individual plans for training were made. For estimating the effects of sports training on development of jumping, eight variables were used. 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. Experiment has been realized in the second part on conditional preparations, and lasted for six weeks with two or three trainings per week. Control group had physical education lessons at their schools twice a week. Data were processed by in variant, multivariate analysis and analysis of covariance. On the results of research and discussion we can say that the model of training we used for development of jumping as a basic factor in experimental group brought statistically bigger difference in improving jumping that it brought in control group.
Directory of Open Access Journals (Sweden)
Rehez Ahlip
2015-01-01
model for the exchange rate with log-normal jump amplitudes and the volatility model with log-uniformly distributed jump amplitudes. We assume that the domestic and foreign stochastic interest rates are governed by the CIR dynamics. The instantaneous volatility is correlated with the dynamics of the exchange rate return, whereas the domestic and foreign short-term rates are assumed to be independent of the dynamics of the exchange rate and its volatility. The main result furnishes a semianalytical formula for the price of the foreign exchange European call option.
Gravitational self-interactions of a degenerate quantum scalar field
Chakrabarty, Sankha S.; Enomoto, Seishi; Han, Yaqi; Sikivie, Pierre; Todarello, Elisa M.
2018-02-01
We develop a formalism to help calculate in quantum field theory the departures from the description of a system by classical field equations. We apply the formalism to a homogeneous condensate with attractive contact interactions and to a homogeneous self-gravitating condensate in critical expansion. In their classical descriptions, such condensates persist forever. We show that in their quantum description, parametric resonance causes quanta to jump in pairs out of the condensate into all modes with wave vector less than some critical value. We calculate, in each case, the time scale over which the homogeneous condensate is depleted and after which a classical description is invalid. We argue that the duration of classicality of inhomogeneous condensates is shorter than that of homogeneous condensates.
Validation of the VERT wearable jump monitor device in elite youth volleyball players
Borges, Thiago O.; Moreira, Alexandre; Bacchi, Renato; Finotti1, Ronaldo L.; Ramos, Mayara; Lopes, Charles R.
2017-01-01
This technical report aims to determine the validity and the accuracy of the VERT Wearable Jump Monitor. The participants of this study were all experienced volleyball players from the U18 category from the Brazilian National team. To assess jump performance, the VERT scores were compared to the VERTEC (jump and reach device). Each athlete performed 3 attack and 3 block jumps in a random, counterbalanced order, and the average score was registered. In the attack jumps, the VERTEC and VERT mean ± SD scores were 70.9±8.2 and 76.3±7.5 cm, respectively, and the typical error of the estimate (TEE) as a coefficient of variation (CV) was 7.8% (90% CL 7.0 to 8.9%). VERTEC and VERT devices presented a very large Pearson’s correlation for attack jumps (r=0.75; 90% CL 0.68 to 0.81). In addition, the mean±SD block jumps were 53.7±6.1 and 58.5±5.7 cm for the VERTEC and VERT, respectively and the TEE as a CV was 7.9% (90% CL 7.1 to 8.9%). Pearson’s correlation coefficient was very large for block jumps (r=0.75; 90% CL 0.67 to 0.81). The VERT device was found to be a very practical tool to quantify jump performance in volleyball players. PMID:29158616
Knee Muscular Control During Jump Landing in Multidirections
Sinsurin, Komsak; Vachalathiti, Roongtiwa; Jalayondeja, Wattana; Limroongreungrat, Weerawat
2016-01-01
Background Jump landing is a complex movement in sports. While competing and practicing, athletes frequently perform multi-planar jump landing. Anticipatory muscle activity could influence the amount of knee flexion and prepare the knee for dynamic weight bearing such as landing tasks. Objectives The aim of the present study was to examine knee muscle function and knee flexion excursion as athletes naturally performed multi-direct...
Directory of Open Access Journals (Sweden)
Vanderka Marián, Longová Katarína, Olasz Dávid, Krčmár Matúš, Walker Simon
2016-09-01
Full Text Available The purpose of the study was to determine the effects of 8 weeks of jump squat training on isometric half squat maximal force production (Fmax and rate of force development over 100ms (RFD100, countermovement jump (CMJ and squat jump (SJ height, and 50 m sprint time in moderately trained men. Sixty eight subjects (~21 years, ~180 cm, ~75 kg were divided into experimental (EXP; n = 36 and control (CON, n = 32 groups. Tests were completed pre-, mid- and post-training. EXP performed jump squat training 3 times per week using loads that allowed all repetitions to be performed with ≥90% of maximum average power output (13 sessions with 4 sets of 8 repetitions and 13 sessions with 8 sets of 4 repetitions. Subjects were given real-time feedback for every repetition during the training sessions. Significant improvements in Fmax from pre- to mid- (Δ ~14%, p<0.001, and from mid- to post-training (Δ ~4%, p < 0.001 in EXP were observed. In CON significantly enhanced Fmax from pre- to mid-training (Δ ~3.5%, p < 0.05 was recorded, but no other significant changes were observed in any other test. In RFD100 significant improvements from pre- to mid-training (Δ ~27%, p < 0.001, as well as from mid- to post-training (Δ ~17%, p < 0.01 were observed. CMJ and SJ height were significantly enhanced from pre- to mid-training (Δ ~10%, ~15%, respectively, p < 0.001 but no further changes occurred from mid- to post-training. Significant improvements in 50 m sprint time from pre- to mid-training (Δ -1%, p < 0.05, and from mid- to post-training (Δ -1.9%, p < 0.001 in EXP were observed. Furthermore, percent changes in EXP were greater than changes in CON during training. It appears that using jump squats with loads that allow repetitions to be performed ≥90% of maximum average power output can simultaneously improve several different athletic performance tasks in the short-term.
Skazalski, C; Whiteley, R; Hansen, C; Bahr, R
2018-05-01
Use of a commercially available wearable device to monitor jump load with elite volleyball players has become common practice. The purpose of this study was to evaluate the validity and reliability of this device, the Vert, to count jumps and measure jump height with professional volleyball players. Jump count accuracy was determined by comparing jumps recorded by the device to jumps observed through systematic video analysis of three practice sessions and two league matches performed by a men's professional volleyball team. Jumps performed by 14 players were each coded for time and jump type and individually matched to device recorded jumps. Jump height validity of the device was examined against reference standards as participants performed countermovement jumps on a force plate and volleyball-specific jumps with a Vertec. The Vert device accurately counted 99.3% of the 3637 jumps performed during practice and match play. The device showed excellent jump height interdevice reliability for two devices placed in the same pouch during volleyball jumps (r = .99, 95% CI 0.98-0.99). The device had a minimum detectable change (MDC) of 9.7 cm and overestimated jump height by an average of 5.5 cm (95% CI 4.5-6.5) across all volleyball jumps. The Vert device demonstrates excellent accuracy counting volleyball-specific jumps during training and competition. While the device is not recommended to measure maximal jumping ability when precision is needed, it provides an acceptable measure of on-court jump height that can be used to monitor athlete jump load. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.
Influence of sports flooring and shoes on impact forces and performance during jump tasks.
Directory of Open Access Journals (Sweden)
Laurent Malisoux
Full Text Available We aim to determine the influence of sports floorings and sports shoes on impact mechanics and performance during standardised jump tasks. Twenty-one male volunteers performed ankle jumps (four consecutive maximal bounds with very dynamic ankle movements and multi-jumps (two consecutive maximal counter-movement jumps on force plates using minimalist and cushioned shoes under 5 sports flooring (SF conditions. The shock absorption properties of the SF, defined as the proportion of peak impact force absorbed by the tested flooring when compared with a concrete hard surface, were: SF0 = 0% (no flooring, SF1 = 19%, SF2 = 26%, SF3 = 37% and SF4 = 45%. Shoe and flooring effects were compared using 2x5 repeated-measures ANOVA with post-hoc Bonferroni-corrected comparisons. A significant interaction between SF and shoe conditions was found for VILR only (p = 0.003. In minimalist shoes, SF influenced Vertical Instantaneous Loading Rate (VILR during ankle jumps (p = 0.006 and multi-jumps (p<0.001, in accordance with shock absorption properties. However, in cushioned shoes, SF influenced VILR during ankle jumps only (p<0.001. Contact Time was the only additional variable affected by SF, but only during multi-jumps in minimalist shoes (p = 0.037. Cushioned shoes induced lower VILR (p<0.001 and lower Contact Time (p≤0.002 during ankle jumps and multi-jumps compared to minimalist shoes. During ankle jumps, cushioned shoes induced greater Peak Vertical Ground Reaction Force (PVGRF, p = 0.002, greater Vertical Average Loading Rate (p<0.001, and lower eccentric (p = 0.008 and concentric (p = 0.004 work. During multi-jumps, PVGRF was lower (p<0.001 and jump height was higher (p<0.001 in cushioned compared to minimalist shoes. In conclusion, cushioning influenced impact forces during standardised jump tasks, whether it was provided by the shoes or the sports flooring. VILR is the variable that was the most affected.
Developing an Enhanced Lightning Jump Algorithm for Operational Use
Schultz, Christopher J.; Petersen, Walter A.; Carey, Lawrence D.
2009-01-01
Overall Goals: 1. Build on the lightning jump framework set through previous studies. 2. Understand what typically occurs in nonsevere convection with respect to increases in lightning. 3. Ultimately develop a lightning jump algorithm for use on the Geostationary Lightning Mapper (GLM). 4 Lightning jump algorithm configurations were developed (2(sigma), 3(sigma), Threshold 10 and Threshold 8). 5 algorithms were tested on a population of 47 nonsevere and 38 severe thunderstorms. Results indicate that the 2(sigma) algorithm performed best over the entire thunderstorm sample set with a POD of 87%, a far of 35%, a CSI of 59% and a HSS of 75%.
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. Copyright © 2016 Elsevier B.V. All rights reserved.
Impact of the focus of attention on vertical jump performance of junior basketball players
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Manojlović Vladimir
2013-01-01
Full Text Available The aim of the research was to determine the impact of the focus of attention on vertical jump performance expressed through a jump height. Thirteen basketball players (body mass = 73,4 kg, height = 186,58 cm, age = 15.12 ± 0.61 y volunteered as participants. All the subject represented a club which participated in the Croatian cadets 1. league in season 2008/09, and were tested during the season. The subjects performed two experiments. In both experiments, they performed 15 repetitions of countermovement jump, whereas in one of the experiments, during the performance of the jumps they were listening to an audio record of spectators. For both type of jumps, the subjects were instructed to stay in the air as long as possible during a single jump (external focus of attention. To determine the differences between jumps, a paired-sample t-test was used with a level of statistical significance set to p ≤ 0.05. Comparison for jump height between both type of jumps revealed no statistically significant difference, although the presented difference should not be denied considering a real match conditions.
Bayesian inference for Markov jump processes with informative observations.
Golightly, Andrew; Wilkinson, Darren J
2015-04-01
In this paper we consider the problem of parameter inference for Markov jump process (MJP) representations of stochastic kinetic models. Since transition probabilities are intractable for most processes of interest yet forward simulation is straightforward, Bayesian inference typically proceeds through computationally intensive methods such as (particle) MCMC. Such methods ostensibly require the ability to simulate trajectories from the conditioned jump process. When observations are highly informative, use of the forward simulator is likely to be inefficient and may even preclude an exact (simulation based) analysis. We therefore propose three methods for improving the efficiency of simulating conditioned jump processes. A conditioned hazard is derived based on an approximation to the jump process, and used to generate end-point conditioned trajectories for use inside an importance sampling algorithm. We also adapt a recently proposed sequential Monte Carlo scheme to our problem. Essentially, trajectories are reweighted at a set of intermediate time points, with more weight assigned to trajectories that are consistent with the next observation. We consider two implementations of this approach, based on two continuous approximations of the MJP. We compare these constructs for a simple tractable jump process before using them to perform inference for a Lotka-Volterra system. The best performing construct is used to infer the parameters governing a simple model of motility regulation in Bacillus subtilis.
Coratella, Giuseppe; Beato, Marco; Milanese, Chiara; Longo, Stefano; Limonta, Eloisa; Rampichini, Susanna; Cè, Emiliano; Bisconti, Angela V; Schena, Federico; Esposito, Fabio
2018-04-01
Coratella, G, Beato, M, Milanese, C, Longo, S, Limonta, E, Rampichini, S, Cè, E, Bisconti, AV, Schena, F, and Esposito, F. Specific adaptations in performance and muscle architecture after weighted jump-squat vs. body mass squat jump training in recreational soccer players. J Strength Cond Res 32(4): 921-929, 2018-The aim of the present study was to compare the effects of weighted jump-squat training (WJST) vs. body mass squat jump training (BMSJT) on quadriceps' muscle architecture, lower-limb lean-mass (LM) and muscle strength, performance in change of direction (COD), and sprint and jump in recreational soccer players. Forty-eight healthy soccer players participated in an offseason randomized controlled trial. Before and after an 8-week training intervention, vastus lateralis pennation angle, fascicle length, muscle thickness, LM, squat 1RM, quadriceps and hamstrings isokinetic peak torque, agility T-test, 10-and 30-m sprints, and squat-jump (SJ) were measured. Although similar increases were observed in muscle thickness, fascicle length increased more in WJST (Effect size [ES] = 1.18, 0.82-1.54) than in BMSJT (ES = 0.54, 0.40-0.68), and pennation angle increased only in BMSJT (ES = 1.03, 0.78-1.29). Greater increases in LM were observed in WJST (ES = 0.44, 0.29-0.59) than in BMSJT (ES = 0.21, 0.07-0.37). The agility T-test (ES = 2.95, 2.72-3.18), 10-m (ES = 0.52, 0.22-0.82), and 30-m sprints (ES = 0.52, 0.23-0.81) improved only in WJST, whereas SJ improved in BMSJT (ES = 0.89, 0.43-1.35) more than in WJST (ES = 0.30, 0.03-0.58). Similar increases in squat 1RM and peak torque occurred in both groups. The greater inertia accumulated within the landing phase in WJST vs. BMSJT has increased the eccentric workload, leading to specific eccentric-like adaptations in muscle architecture. The selective improvements in COD in WJST may be related to the increased braking ability generated by the enhanced eccentric workload.
The effects of temperature and body mass on jump performance of the locust Locusta migratoria.
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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.
Jump in current at the gap voltage in a superconducting junction
International Nuclear Information System (INIS)
Coombes, J.M.; Carbotte, J.P.
1986-01-01
For many materials not previously considered, we have calculated the jump, at the gap voltage, in the quasiparticle current of a tunnel junction. An empirical relationship between the jump and the effective electron-phonon coupling λ-μ/sup */ previously established is confirmed. Further, a new and equally as accurate correlation is found with the strong coupling index T/sub c//ω/sub ln/, where T/sub c/ is the critical temperature and ω/sub ln/ a specific characteristic phonon energy. A simple formula for the jump which includes a strong-coupling correction is derived and found to fit the observed correlation well. Finally, we study the effect on the jump of unusual values of Coulomb pseudopotential μ/sup */. Also a δ-function electron-phonon spectral density α 2 F(ω) is used to help in the understanding of the range of values that is possible for the jump when α 2 F(ω) is not restricted to realistic shapes
Study of density jump in helicon-wave induced H2 plasma
International Nuclear Information System (INIS)
Jiang Fan; Cheng Xinlu; Xiong Zhenwei; Wu Weidong; Wang Yuying; Gao Yingxue; Dai Yang
2012-01-01
Hydrogen plasmas electron density and electron energy distribution function EEDF were studied with Langmuir probe. Two jumps were observed in the variation of the electron density with the radio frequency power. The relative intensity ratio of hydrogen plasmas spectrum line H α , H β and H γ validated this phenomenon. Two density jumps illuminated the transition of discharge mode,which labeled as capacitive, inductive and helicon-wave mode. In this work, the density jumps are explained from two sides, one is the interaction between electrons and hydrogen molecules, the other is Nagoya type III (N-type) antenna-plasma coupling. With the increase of radiofrequency power, the interaction between electron and hydrogen molecule has been enhanced which causes the electron density jumps. The antenna couples well to plasmas when transverse field E y is maximum, and the wave vector of k z locates at π/l a or 3π/l a , corresponding to the first and second density jump. (authors)
Biomechanical aspects of new techniques in alpine skiing and ski-jumping.
Müller, Erich; Schwameder, Hermann
2003-09-01
There have been considerable changes in equipment design and movement patterns in the past few years both in alpine skiing and ski-jumping. These developments have been matched by methods of analysing movements in field conditions. They have yielded new insights into the skills of these specific winter sports. Analytical techniques have included electromyography, kinetic and kinematic methods and computer simulations. Our aim here is to review biomechanical research in alpine skiing and ski-jumping. We present in detail the techniques currently used in alpine skiing (carving technique) and ski-jumping (V-technique), primarily using data from the authors' own research. Finally, we present a summary of the most important results in biomechanical research both in alpine skiing and ski-jumping. This includes an analysis of specific conditions in alpine skiing (type of turn, terrain, snow, speed, etc.) and the effects of equipment, materials and individual-specific abilities on performance, safety and joint loading in ski-jumping.
Factors that influence ground reaction force profiles during counter movement jumping.
Eagles, Alexander N; Sayers, Mark G; Lovell, Dale I
2017-05-01
The purpose of this study was to examine how hip, knee and ankle kinetics and kinematics influence effective impulse production during countermovement jumps. Eighteen semi-professional soccer players (22.8±2.2 years) volunteered to participate in the study. Participants completed three maximal countermovement jumps on two force platforms (1000 Hz) that were linked to a nine camera infrared motion capture system (500 Hz). Kinetic and kinematic data revealed jumpers who fail to achieve uniform ground reaction force curves that result in optimal impulse production during their jump always display hip adduction and or hip internal rotation during the concentric phase of the countermovement jump. The variation of hip adduction and or internal rotation likely represents failed joint transition during the concentric phase of the countermovement jump and appears to account for a non-uniform force trace seen in these jumpers. The findings suggest rehabilitation and conditioning exercises for injury prevention and performance may benefit from targeting frontal and transverse plane movement.
Inference for the jump part of quadratic variation of Itô semimartingales
DEFF Research Database (Denmark)
Veraart, Almut
Recent research has focused on modelling asset prices by Itô semimartingales. In such a modelling framework, the quadratic variation consists of a continuous and a jump component. This paper is about inference on the jump part of the quadratic variation, which can be estimated by the difference...... of realised variance and realised multipower variation. The main contribution of this paper is twofold. First, it provides a bivariate asymptotic limit theory for realised variance and realised multipower variation in the presence of jumps. Second, this paper presents new, consistent estimators for the jump...
Inference for the jump part of quadratic variation of Itô semimartingales
DEFF Research Database (Denmark)
Veraart, Almut
2010-01-01
Recent research has focused on modeling asset prices by Itô semimartingales. In such a modeling framework, the quadratic variation consists of a continuous and a jump component. This paper is about inference on the jump part of the quadratic variation, which can be estimated by the difference...... of realized variance and realized multipower variation. The main contribution of this paper is twofold. First, it provides a bivariate asymptotic limit theory for realized variance and realized multipower variation in the presence of jumps. Second, this paper presents new, consistent estimators for the jump...
Entanglement evolution for quantum trajectories
International Nuclear Information System (INIS)
Vogelsberger, S; Spehner, D
2011-01-01
Entanglement is a key resource in quantum information. It can be destroyed or sometimes created by interactions with a reservoir. In recent years, much attention has been devoted to the phenomena of entanglement sudden death and sudden birth, i.e., the sudden disappearance or revival of entanglement at finite times resulting from a coupling of the quantum system to its environment. We investigate the evolution of the entanglement of noninteracting qubits coupled to reservoirs under monitoring of the reservoirs by means of continuous measurements. Because of these measurements, the qubits remain at all times in a pure state, which evolves randomly. To each measurement result (or 'realization') corresponds a quantum trajectory in the Hilbert space of the qubits. We show that for two qubits coupled to independent baths subjected to local measurements, the average of the qubits' concurrence over all quantum trajectories is either constant or decays exponentially. The corresponding decay rate depends on the measurement scheme only. This result contrasts with the entanglement sudden death phenomenon exhibited by the qubits' density matrix in the absence of measurements. Our analysis applies to arbitrary quantum jump dynamics (photon counting) as well as to quantum state diffusion (homodyne or heterodyne detections) in the Markov limit. We discuss the best measurement schemes to protect the entanglement of the qubits. We also analyze the case of two qubits coupled to a common bath. Then, the average concurrence can vanish at discrete times and may coincide with the concurrence of the density matrix. The results explained in this article have been presented during the 'Fifth International Workshop DICE2010' by the first author and have been the subject of a prior publication.
Impact of Androstenone on Leash Pulling and Jumping Up in Dogs
Directory of Open Access Journals (Sweden)
Glenna Pirner
2016-05-01
Full Text Available Dogs are relinquished to shelters due to behavioral problems, such as leash pulling and jumping up. Interomones are chemical cues produced by one species that elicit a response in a different species. We reported earlier that androstenone, a swine sex pheromone, acts as an interomone to reduce barking in dogs. Here we report two models using 10 dogs/study: a dog jumping and a dog walking model. For the leash-pulling model, each time the dog pulled on the leash the walker either did nothing (NOT, or sprayed the dog with water (H2O, androstenone + water (ANH, androstenone 0.1 µg/mL (AND1, or androstenone 1.0 µg/mL (AND2. The number of pulls during each walk was counted. For the jumping up model, each time the dog jumped the researcher did nothing (NOT, or sprayed the dog with H2O, ANH, AND1, or AND2. The number of jumps and the time between jumps were recorded. In Study 1, ANH, AND1, and AND2 each reduced leash pulling more than NOT and H2O (p< 0.01. In Study 2, all treatments were effective in reducing jumping up behavior. Androstenone reduced jumping up, but not beyond that elicited by a spray of water alone. We conclude that androstenone in multiple delivery vehicles reduced leash pulling. The burst of air intended as a disruptive stimulus in the correction sprays may be too harsh for more sensitive dogs, and as such use of these sprays is cautioned in these animals. For other dogs, this interomone can be used to stop some behavior immediately or as a part of a training program to reduce undesirable behavior.
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...... 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...
Variability of Jump Kinetics Related to Training Load in Elite Female Basketball.
Legg, Jan; Pyne, David B; Semple, Stuart; Ball, Nick
2017-11-04
The purpose of this study was to quantify changes in jump performance and variability in elite female basketballers. Junior and senior female representative basketball players ( n = 10) aged 18 ± 2 years participated in this study. Countermovement jump (CMJ) data was collected with a Gymaware™ optical encoder at pre-, mid-, and post-season time points across 10 weeks. Jump performance was maintained across the course of the full season (from pre to post). Concentric peak velocity, jump height, and dip showed the most stability from pre- to post-season, with the %CV ranging from 5.6⁻8.9%. In the period of the highest training load (mid-season), the variability of within-subject performance was reduced by approximately 2⁻4% in all measures except for jump height. Altered jump mechanics through a small (0.26 effect size) increase in dip were evident at mid-season, suggesting that CMJ analysis is useful for coaches to use as an in-season monitoring tool. The highest coefficient of variation (8⁻22%CV) in inter-set scores in all measures except eccentric peak velocity also occurred mid-season. It appears that in-season load not only impairs jump performance, but also movement variability in basketball players.
Variability of Jump Kinetics Related to Training Load in Elite Female Basketball
Directory of Open Access Journals (Sweden)
Jan Legg
2017-11-01
Full Text Available The purpose of this study was to quantify changes in jump performance and variability in elite female basketballers. Junior and senior female representative basketball players (n = 10 aged 18 ± 2 years participated in this study. Countermovement jump (CMJ data was collected with a Gymaware™ optical encoder at pre-, mid-, and post-season time points across 10 weeks. Jump performance was maintained across the course of the full season (from pre to post. Concentric peak velocity, jump height, and dip showed the most stability from pre- to post-season, with the %CV ranging from 5.6–8.9%. In the period of the highest training load (mid-season, the variability of within-subject performance was reduced by approximately 2–4% in all measures except for jump height. Altered jump mechanics through a small (0.26 effect size increase in dip were evident at mid-season, suggesting that CMJ analysis is useful for coaches to use as an in-season monitoring tool. The highest coefficient of variation (8–22%CV in inter-set scores in all measures except eccentric peak velocity also occurred mid-season. It appears that in-season load not only impairs jump performance, but also movement variability in basketball players.
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...
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....
Jumps in the curve of creep of the stainless steel
International Nuclear Information System (INIS)
Silveira, T.L.; Monteiro, S.N.
The discontinuous flow observed in creep for several stainless steels at certain streels conditions in the interval of temperatures from 550 to 800 0 C has been investigated. This phenomenon appears as repetitive jumps with strain and stress increments that could be evaluated and related to the tests variables. The stress increment increases, consistently, with the stress level at the jump. This Δo versus sigma relation is due to strain aging effects and is a consequence of the variation of the stain rate during the deformation band propagation which causes the jump [pt
MENINGKATKAN HASIL BELAJAR LOMPAT JAUH GAYA JONGKOK MELALUI PERMAINAN JUMP BOX
Directory of Open Access Journals (Sweden)
Ali Khafidin S
2015-08-01
Full Text Available The aim in this study was to determine the learning outcome long jump squat style through play approach jump box on fourth grade students N Yamansari 01 2013/2014 academic year. This research is a classroom action research. This study consisted of two cycles. Each cycle consists of planning, action, observation and reflection. This research was conducted in the District 01 Elementary School Yamansari Lebaksiu Tegal with research subjects IV class with 40 students consisting of 21 male students and 19 female students. The research instrument used is the observation sheet student activity, teacher observation sheet activities and practice tests. Technique data analysis was done descriptively and through hitingan predetermined formula. The results showed that the learning outcomes long jump squat style by using a jump box game this looks positive impact on students' mastery learning outcomes that exceed a predetermined KKM is 75 has risen in the first cycle of learning completeness reached 72.50% with a mean value -rata 78, while in the second cycle learning completeness reached 92.50% with an average value of 81.67. It can be concluded that learning style long jump squat jump box game approach has a positive influence, which can improve learning outcomes, interest and motivation to learn.
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
Effect of liquid surface tension on circular and linear hydraulic jumps; theory and experiments
Bhagat, Rajesh Kumar; Jha, Narsing Kumar; Linden, Paul F.; Wilson, David Ian
2017-11-01
The hydraulic jump has attracted considerable attention since Rayleigh published his account in 1914. Watson (1964) proposed the first satisfactory explanation of the circular hydraulic jump by balancing the momentum and hydrostatic pressure across the jump, but this solution did not explain what actually causes the jump to form. Bohr et al. (1992) showed that the hydraulic jump happens close to the point where the local Froude number equals to one, suggesting a balance between inertial and hydrostatic contributions. Bush & Aristoff (2003) subsequently incorporated the effect of surface tension and showed that this is important when the jump radius is small. In this study, we propose a new account to explain the formation and evolution of hydraulic jumps under conditions where the jump radius is strongly influenced by the liquid surface tension. The theory is compared with experiments employing liquids of different surface tension and different viscosity, in circular and linear configurations. The model predictions and the experimental results show excellent agreement. Commonwealth Scholarship Commission, St. John's college, University of Cambridge.
Estimation and prediction under local volatility jump-diffusion model
Kim, Namhyoung; Lee, Younhee
2018-02-01
Volatility is an important factor in operating a company and managing risk. In the portfolio optimization and risk hedging using the option, the value of the option is evaluated using the volatility model. Various attempts have been made to predict option value. Recent studies have shown that stochastic volatility models and jump-diffusion models reflect stock price movements accurately. However, these models have practical limitations. Combining them with the local volatility model, which is widely used among practitioners, may lead to better performance. In this study, we propose a more effective and efficient method of estimating option prices by combining the local volatility model with the jump-diffusion model and apply it using both artificial and actual market data to evaluate its performance. The calibration process for estimating the jump parameters and local volatility surfaces is divided into three stages. We apply the local volatility model, stochastic volatility model, and local volatility jump-diffusion model estimated by the proposed method to KOSPI 200 index option pricing. The proposed method displays good estimation and prediction performance.
AGS tune jump power supply design and test
International Nuclear Information System (INIS)
Mi, J.; Glenn, J.W.; Huang, H.; Marneris, I.; Rosas, P.; Sandberg, J.; Tan, Y.; Zhang, W.
2011-01-01
A horizontal tune jump system has been installed to overcome the horizontal intrinsic spin resonances, which requires jumping the horizontal tune 0.04 units 82 times, 41 up and 41 down. Two quadruple magnets have been installed in AGS ring to perform this. The pulsed magnet current ranges from about 140A near injection to about 1400A later. The current pulse rise and fall time are around 100uS and flat tops time is around 4mS. These quadruples have separated supplies. This tune jump pulse power supply employees all semiconductor parts as well as the main switches. During dummy load and magnet testing, the test results showed that the power supply could meet the specification. This article will describe some details of power supply simulation, design and testing. Some test waveforms and pictures are presented in this paper.
Local uncontrollability for affine control systems with jumps
Treanţă, Savin
2017-09-01
This paper investigates affine control systems with jumps for which the ideal If(g1, …, gm) generated by the drift vector field f in the Lie algebra L(f, g1, …, gm) can be imbedded as a kernel of a linear first-order partial differential equation. It will lead us to uncontrollable affine control systems with jumps for which the corresponding reachable sets are included in explicitly described differentiable manifolds.
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
On Pathos Adjacency Cut Vertex Jump Graph of a Tree
Nagesh.H.M; R.Chandrasekhar
2014-01-01
In this paper the concept of pathos adjacency cut vertex jump graph PJC(T) of a tree T is introduced. We also present a characterization of graphs whose pathos adjacency cut vertex jump graphs are planar, outerplanar, minimally non-outerplanar, Eulerian and Hamiltonian.
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.
Ski jump takeoff performance predictions for a mixed-flow, remote-lift STOVL aircraft
Birckelbaw, Lourdes G.
1992-01-01
A ski jump model was developed to predict ski jump takeoff performance for a short takeoff and vertical landing (STOVL) aircraft. The objective was to verify the model with results from a piloted simulation of a mixed flow, remote lift STOVL aircraft. The prediction model is discussed. The predicted results are compared with the piloted simulation results. The ski jump model can be utilized for basic research of other thrust vectoring STOVL aircraft performing a ski jump takeoff.
Correlation between toe flexor strength and ankle dorsiflexion ROM during the countermovement jump.
Yun, Sung Joon; Kim, Moon-Hwan; Weon, Jong-Hyuck; Kim, Young; Jung, Sung-Hoon; Kwon, Oh-Yun
2016-08-01
[Purpose] This study assessed the relationships between peak toe flexor muscle strength, ankle dorsiflexion range of motion, and countermovement jump height. [Subjects and Methods] Eighteen healthy volunteers participated in the study. Each participant completed tests for peak toe flexor muscle strength, ankle dorsiflexion range of motion, and countermovement jump height. [Results] The results showed (1) a moderate correlation between ankle dorsiflexion range of motion and countermovement jump height and (2) a high correlation between peak first toe flexor muscle strength and countermovement jump height. Peak first toe flexor muscle strength and ankle dorsiflexion range of motion are the main contributors to countermovement jump performance. [Conclusion] These findings indicate that the measurement of peak first toe flexor muscle strength and ankle dorsiflexion range of motion may be useful in clinical practice for improving jump performance in athletes training for sports such as volleyball and basketball.
Directory of Open Access Journals (Sweden)
Rashiti Naser
2011-09-01
Full Text Available In order to examine the impact of anthropometrical characteristics and motor skills during the tests’ implementation of the jump forward and triple jump from place, the experimental research was carried out on a sample of 100 second year students from the Faculty of Physical Education and Sport in Prishtine. For the purposes of this study were measured eight anthropometrical characteristics and ten tests for assessing motor skills, which made the predictor system of variables. To assess the explosive force of the type of jumpiness, applied were tests long jump forward and triple jump from place. Data was processed with the basic descriptive statistical parameters and regression analysis. Based on the results of this research and the discussion ,can be concluded that the applied system of predictor motor tests, have significant influence on the manifestation of the explosive force of students at the Faculty of Physical Education and Sport in Prishtine, i.e., it is possible to predict (forecast the results of tests for explosive power based on the predictor system of respondents
Directory of Open Access Journals (Sweden)
Matheus Machado Gomes
2009-01-01
Full Text Available http://dx.doi.org/10.5007/1980-0037.2009v11n4p392 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.
Woolstenhulme, Mandy T; Griffiths, Christine M; Woolstenhulme, Emily M; Parcell, Allen C
2006-11-01
Stretching is often included as part of a warm-up procedure for basketball activity. However, the efficacy of stretching with respect to sport performance has come into question. We determined the effects of 4 different warm-up protocols followed by 20 minutes of basketball activity on flexibility and vertical jump height. Subjects participated in 6 weeks (2 times per week) of warm-up and basketball activity. The warm-up groups participated in ballistic stretching, static stretching, sprinting, or basketball shooting (control group). We asked 3 questions. First, what effect does 6 weeks of warm-up exercise and basketball play have on both flexibility and vertical jump height? We measured sit and reach and vertical jump height before (week -1) and after (week 7) the 6 weeks. Flexibility increased for the ballistic, static, and sprint groups compared to the control group (p vertical jump height did not change for any of the groups. Our second question was what is the acute effect of each warm-up on vertical jump height? We measured vertical jump immediately after the warm-up on 4 separate occasions during the 6 weeks (at weeks 0, 2, 4, and 6). Vertical jump height was not different for any group. Finally, our third question was what is the acute effect of each warm-up on vertical jump height following 20 minutes of basketball play? We measured vertical jump height immediately following 20 minutes of basketball play at weeks 0, 2, 4, and 6. Only the ballistic stretching group demonstrated an acute increase in vertical jump 20 minutes after basketball play (p basketball play, as it is beneficial to vertical jump performance.
Hydraulic jump and Bernoulli equation in nonlinear shallow water model
Sun, Wen-Yih
2018-06-01
A shallow water model was applied to study the hydraulic jump and Bernoulli equation across the jump. On a flat terrain, when a supercritical flow plunges into a subcritical flow, discontinuity develops on velocity and Bernoulli function across the jump. The shock generated by the obstacle may propagate downstream and upstream. The latter reflected from the inflow boundary, moves downstream and leaves the domain. Before the reflected wave reaching the obstacle, the short-term integration (i.e., quasi-steady) simulations agree with Houghton and Kasahara's results, which may have unphysical complex solutions. The quasi-steady flow is quickly disturbed by the reflected wave, finally, flow reaches steady and becomes critical without complex solutions. The results also indicate that Bernoulli function is discontinuous but the potential of mass flux remains constant across the jump. The latter can be used to predict velocity/height in a steady flow.
Swarm algorithms with chaotic jumps for optimization of multimodal functions
Krohling, Renato A.; Mendel, Eduardo; Campos, Mauro
2011-11-01
In this article, the use of some well-known versions of particle swarm optimization (PSO) namely the canonical PSO, the bare bones PSO (BBPSO) and the fully informed particle swarm (FIPS) is investigated on multimodal optimization problems. A hybrid approach which consists of swarm algorithms combined with a jump strategy in order to escape from local optima is developed and tested. The jump strategy is based on the chaotic logistic map. The hybrid algorithm was tested for all three versions of PSO and simulation results show that the addition of the jump strategy improves the performance of swarm algorithms for most of the investigated optimization problems. Comparison with the off-the-shelf PSO with local topology (l best model) has also been performed and indicates the superior performance of the standard PSO with chaotic jump over the standard both using local topology (l best model).
Increased medial foot loading during drop jump in subjects with patellofemoral pain
DEFF Research Database (Denmark)
Rathleff, Michael S; Richter, Camilla; Brushøj, Christoffer
2014-01-01
PURPOSE: To compare medial-to-lateral plantar forces during drop jump and single leg squat in individuals with and without patellofemoral pain. METHODS: This cross-sectional study compared 23 young adults with patellofemoral pain to 20 age- and sex-matched controls without knee pain. The plantar...... pressure distribution was collected during drop jump and single leg squat using pressure-sensitive Pedar insoles, inserted into a standard flat shoe. The primary outcome was the medial-to-lateral force, quantified as the peak force under the medial forefoot as the percentage of force under the total...... forefoot during drop jump. Secondary outcomes included peak medial-to-lateral force during single leg squat and mean forces during drop jump and single leg squat. RESULTS: The primary outcome showed that individuals with patellofemoral pain had a 22 % higher medial-to-lateral peak force during drop jump...
Physical and Dynamical Linkages Between Lightning Jumps and Storm Conceptual Models
Schultz, Christopher J.; Carey, Lawrence D.; Schultz, Elise V.; Blakeslee, Richard J.; Goodman, Steven J.
2014-01-01
The presence and rates of total lightning are both correlated to and physically dependent upon storm updraft strength, mixed phase precipitation volume and the size of the charging zone. The updraft modulates the ingredients necessary for electrification within a thunderstorm, while the updraft also plays a critical role in the development of severe and hazardous weather. Therefore utilizing this relationship, the monitoring of lightning rates and jumps provides an additional piece of information on the evolution of a thunderstorm, more often than not, at higher temporal resolution than current operational radar systems. This correlation is the basis for the total lightning jump algorithm that has been developed in recent years. Currently, the lightning jump algorithm is being tested in two separate but important efforts. Schultz et al. (2014; this conference) is exploring the transition of the algorithm from its research based formulation to a fully objective algorithm that includes storm tracking, Geostationary Lightning Mapper (GLM) Proxy data and the lightning jump algorithm. Chronis et al. (2014) provides context for the transition to current operational forecasting using lightning mapping array based products. However, what remains is an end-to-end physical and dynamical basis for coupling total lightning flash rates to severe storm manifestation, so the forecaster has a reason beyond simple correlation to utilize the lightning jump algorithm within their severe storm conceptual models. Therefore, the physical basis for the lightning jump algorithm in relation to severe storm dynamics and microphysics is a key component that must be further explored. Many radar studies have examined flash rates and their relationship to updraft strength, updraft volume, precipitation-sized ice mass, etc.; however, their relationship specifically to lightning jumps is fragmented within the literature. Thus the goal of this study is to use multiple Doppler and polarimetric
pH-jump induced α-helix folding of poly-L-glutamic acid
International Nuclear Information System (INIS)
Donten, Mateusz L.; Hamm, Peter
2013-01-01
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
A simple method for quantifying jump loads in volleyball athletes.
Charlton, Paula C; Kenneally-Dabrowski, Claire; Sheppard, Jeremy; Spratford, Wayne
2017-03-01
Evaluate the validity of a commercially available wearable device, the Vert, for measuring vertical displacement and jump count in volleyball athletes. Propose a potential method of quantifying external load during training and match play within this population. Validation study. The ability of the Vert device to measure vertical displacement in male, junior elite volleyball athletes was assessed against reference standard laboratory motion analysis. The ability of the Vert device to count jumps during training and match-play was assessed via comparison with retrospective video analysis to determine precision and recall. A method of quantifying external load, known as the load index (LdIx) algorithm was proposed using the product of the jump count and average kinetic energy. Correlation between two separate Vert devices and three-dimensional trajectory data were good to excellent for all jump types performed (r=0.83-0.97), with a mean bias of between 3.57-4.28cm. When matched against jumps identified through video analysis, the Vert demonstrated excellent precision (0.995-1.000) evidenced by a low number of false positives. The number of false negatives identified with the Vert was higher resulting in lower recall values (0.814-0.930). The Vert is a commercially available tool that has potential for measuring vertical displacement and jump count in elite junior volleyball athletes without the need for time-consuming analysis and bespoke software. Subsequently, allowing the collected data to better quantify load using the proposed algorithm (LdIx). Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.
Loaded and unloaded jump performance of top-level volleyball players from different age categories
Kitamura, Katia; Pereira, Lucas Adriano; Kobal, Ronaldo; Cal Abad, Cesar Cavinato; Finotti, Ronaldo; Nakamura, Fábio Yuzo
2017-01-01
The aim of this study was to investigate the differences in loaded and unloaded jump performances between different age categories of top-level volleyball players from the same club. Forty-three volleyball players were divided into four age groups: under-17, under-19, under-21 and professional. Vertical jumping height for squat jump (SJ), countermovement jump (CMJ) and CMJ with arm swing (CMJa) and mean propulsive velocity (MPV) in the loaded jump squat exercise with 40% of the athlete’s body mass were compared among the different age categories, considering body mass as a covariate. SJ and CMJ jump height values were higher for professional and under-21 players than under-17 players (pvolleyball players. Therefore, to increase the vertical jumping ability of these team sport athletes throughout their long-term development, coaches and strength and conditioning professionals are encouraged to implement consistent neuromuscular training strategies, in accordance with the specific needs and physiological characteristics of each age group. PMID:29158621
Mechanism design and optimization of a bionic kangaroo jumping robot
Zhang, Y. H.; Zheng, L.; Ge, W. J.; Zou, Z. H.
2018-03-01
Hopping robots have broad application prospects in the fields of military reconnaissance, field search or life rescue. However, current hopping robots still face the problems of weak jumping ability and load bearing. Inspired by the jumping of kangaroo, we design a Kangaroo hopping robot “Zbot”, which has two degrees of freedom and three joints. The geared five-bar mechanism is used to decouple the knee and ankle joints of the robot. In order to get a bionic performance, the coupling mechanism parameters are optimized. The simulation and experiments show that the robot has an excellent jumping ability and load capacity.
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.
Afrika Statistika ISSN 2316-090X Jump Resonance in Wind-Felled ...
African Journals Online (AJOL)
jump function. Duffing's model, describing function and Chebyshev polynomials were used .... this study to develop polynomial growth equation for plantains and plantain jump resonance ..... New technologies to increase root health and crop.
Effect of cluster sets on plyometric jump power.
Moreno, Steven D; Brown, Lee E; Coburn, Jared W; Judelson, Daniel A
2014-09-01
Cluster sets may lead to enhanced power (PW) production by allowing for partial recovery. The purpose of this study was to determine the effects of cluster sets vs. traditional sets on plyometric jump PW, ground reaction force, take-off velocity (TOV), and jump height (JH). Twenty-six recreationally trained college men completed 3 testing sessions, which involved performing repeated body-weight (BW) plyometric squat jumps across 3 different set configurations: traditional (2 sets of 10 with 90-second rest between sets), cluster 1 (4 sets of 5 with 30-second rest between sets), and cluster 2 (10 sets of 2 with 10-second rest between sets). Ground reaction force results demonstrated no interaction or main effect for condition, but there was a significant (p ≤ 0.05) main effect for repetition, where repetition 1 was significantly less than repetitions 3-5, 7-10, 12-15, and 17-20. For TOV, PW, and JH, there were significant interactions. Take-off velocity resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 7-10 and 17-20, but was significantly less than repetition 13; cluster 1, repetition 1 was significantly less than repetitions 2-5; and cluster 2, there were no significant differences. Power resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 4-10 and 14-20; cluster 1, repetition 1 was significantly greater than repetitions 7-10 and 12-20; and cluster 2, repetition 1 was significantly greater than repetitions 3, 6-18, and 20. Jump height resulted in the following: Traditional, repetition 1 was significantly greater than repetitions 18-20, but was significantly less than repetitions 3 and 13. For cluster 1 and cluster 2, there were no significant differences. These results demonstrate that cluster sets, specifically 10 sets of 2, allow for a greater maintenance of PW, TOV, and JH compared with a traditional 2 sets of 10 when performing repeated BW plyometric squat jumps. A lack
Reversal time of jump-noise magnetization dynamics in nanomagnets via Monte Carlo simulations
Parthasarathy, Arun; Rakheja, Shaloo
2018-06-01
The jump-noise is a nonhomogeneous Poisson process which models thermal effects in magnetization dynamics, with special applications in low temperature escape rate phenomena. In this work, we develop improved numerical methods for Monte Carlo simulation of the jump-noise dynamics and validate the method by comparing the stationary distribution obtained empirically against the Boltzmann distribution. In accordance with the Néel-Brown theory, the jump-noise dynamics display an exponential relaxation toward equilibrium with a characteristic reversal time, which we extract for nanomagnets with uniaxial and cubic anisotropy. We relate the jump-noise dynamics to the equivalent Landau-Lifshitz dynamics up to second order correction for a general energy landscape and obtain the analogous Néel-Brown theory's solution of the reversal time. We find that the reversal time of jump-noise dynamics is characterized by Néel-Brown theory's solution at the energy saddle point for small noise. For large noise, the magnetization reversal due to jump-noise dynamics phenomenologically represents macroscopic tunneling of magnetization.
The "Suicide Guard Rail": a minimal structural intervention in hospitals reduces suicide jumps.
Mohl, Andreas; Stulz, Niklaus; Martin, Andrea; Eigenmann, Franz; Hepp, Urs; Hüsler, Jürg; Beer, Jürg H
2012-08-04
Jumping from heights is a readily available and lethal method of suicide. This study examined the effectiveness of a minimal structural intervention in preventing suicide jumps at a Swiss general teaching hospital. Following a series of suicide jumps out of the hospital's windows, a metal guard rail was installed at each window of the high-rise building. In the 114 months prior to the installation of the metal guard rail, 10 suicides by jumping out of the hospital's windows occurred among 119,269 inpatients. This figure was significantly reduced to 2 fatal incidents among 104,435 inpatients treated during the 78 months immediately following the installation of the rails at the hospital's windows (χ2 = 4.34, df = 1, p = .037). Even a minimal structural intervention might prevent suicide jumps in a general hospital. Further work is needed to examine the effectiveness of minimal structural interventions in preventing suicide jumps.
Hydraulic jumps in a partially filled rotating cylinder
International Nuclear Information System (INIS)
Lundgren, T.S.; Berman, A.S.
1979-06-01
A nonlinear analysis is made of the fluid dynamics of a thin film of liquid completely spun up along the cylindrical wall of a rotating cylinder. The analysis allows for the possibility of hydraulic jumps in the liquid film. Conditions are simulated under which jumps can occur. Under the assumption that synchronous runouts are small relative to the film thickness, a sample calculation of jump position and extent for various operating frequencies is presented. Comparison with experimental observations indicate good qualitative agreement between the analysis and the experiment. Under the additional restriction of constant film thickness and a simple lumped-parameter dynamic model for the rotor and its supports, an analysis is also provided which predicts the amplitude and frequency of the asynchronous runout as a function of operating frequency. A numerical example of the results of such a calculation is provided. 6 figures
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.
Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps
Directory of Open Access Journals (Sweden)
Pantoja Patrícia Dias
2014-07-01
Full Text Available This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions.
Neuromuscular Responses of Elite Skaters During Different Roller Figure Skating Jumps
Pantoja, Patrícia Dias; Mello, André; Liedtke, Giane Veiga; Kanitz, Ana Carolina; Cadore, Eduardo Lusa; Pinto, Stephanie Santana; Alberton, Cristine Lima; Kruel, Luiz Fernando Martins
2014-01-01
This study aimed to describe the neuromuscular activity of elite athletes who performed various roller figure skating jumps, to determine whether the muscle activation is greater during jumps with more rotations and in which phase the muscles are more active. This study also aimed to analyze if there is any difference in the muscle activity pattern between female and male skaters. Four elite skaters were evaluated, and each participated in two experimental sessions. During the first session, anthropometric data were collected, and the consent forms were signed. For the second session, neuromuscular data were collected during jumps, which were performed with skates at a rink. The following four roller figure skating jumps were evaluated: single Axel, double Axel, double Mapes and triple Mapes. The neuromuscular activity of the following seven muscles was obtained with an electromyograph which was fixed to the waist of each skater with a strap: biceps femoris, lateral gastrocnemius, tibialis anterior, rectus femoris, vastus lateralis, vastus medialis and gluteus maximus. The signal was transmitted wirelessly to a laptop. During the roller figure skating jumps, the lateral gastrocnemius, rectus femoris, vastus lateralis, biceps femoris and gluteus maximus, showed more activation during the jumps with more rotations, and the activation mainly occurred during the propulsion and flight phases. Female skaters demonstrated higher muscle activities in tibialis anterior, vastus lateralis, vastus medialis and gluteus maximus during the landing phase of the triple Mapes, when compared to their male counterparts. The results obtained in this study should be considered when planning training programs with specific exercises that closely resemble the roller figure skating jumps. This may be important for the success of elite skaters in competitions. PMID:25114728
Adaptive jump barrier height in Monte Carlo configuration kinetics.
Energy Technology Data Exchange (ETDEWEB)
Leitner, Martin; Pfeiler, Wolfgang; Pueschl, Wolfgang [Dynamics of Condensed Systems, Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Wien (Austria); Vogtenhuber, Doris [Computational Materials Science, Faculty of Physics, University of Vienna, Sensengasse 8, A-1090 Wien (Austria)
2008-07-01
In usual MC simulations of configuration kinetics atom jump probabilities are calculated from energies of the initial and/or final bound states of the moving atom, leaving aside the exact energy of the intermediate saddle point state. This energy may however be critically influenced by the local atomic environment. We propose a strategy to explicitly take account of this influence. The basis is ab initio calculation of representative jump paths in the framework of the nudged elastic band method. From these results, an influence function is derived which modifies the energy of the saddle point and therefore the effective jump barrier height as calculated from the initial and final states according to a cluster expansion scheme. The overall effect is demonstrated on the NiAl system.
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
Wave structure in the radial film flow with a circular hydraulic jump
Rao, A.; Arakeri, J. H.
A circular hydraulic jump is commonly seen when a circular liquid jet impinges on a horizontal plate. Measurements of the film thickness, jump radius and the wave structure for various jet Reynolds numbers are reported. Film thickness measurements are made using an electrical contact method for regions both upstream and downstream of the jump over circular plates without a barrier at the edge. The jump radius and the separation bubble length are measured for various flow rates, plate edge conditions, and radii. Flow visualization using high-speed photography is used to study wave structure and transition. Waves on the jet amplify in the film region upstream of the jump. At high flow rates, the waves amplify enough to cause three-dimensional breakdown and what seems like transition to turbulence. This surface wave induced transition is different from the traditional route and can be exploited to enhance heat and mass transfer rates.
Acute kinematic and kinetic adaptations to wearable resistance during vertical jumping.
Macadam, Paul; Simperingham, Kim D; Cronin, John B; Couture, Grace; Evison, Chloe
2017-06-01
One variation of vertical jump (VJ) training is resisted or weighted jump training, where wearable resistance (WR) enables jumping to be overloaded in a movement specific manner. A two-way analysis of variance with Bonferroni post hoc contrasts was used to determine the acute changes in VJ performance with differing load magnitudes and load placements. Kinematic and kinetic data were quantified using a force plate and contact mat. Twenty sport active subjects (age: 27.8 ± 3.8 years; body mass (BM): 70.2 ± 12.2 kg; height: 1.74 ± 0.78 m) volunteered to participate in the study. Subjects performed the counter movement jump (CMJ), drop jump (DJ) and pogo jump (PJ) wearing no resistance, 3% or 6% BM affixed to the upper or lower body. The main finding in terms of the landing phase was that the effect of WR was non-significant (P > .05) on peak ground reaction force. With regard to the propulsive phase the main findings were that for both the CMJ and DJ, WR resulted in a significant (P sports where VJ's are important components as it may provide a novel movement specific training stimulus. Highlights WR of 3 or 6 % BM provided a means to overload the subjects in this study resulting in decreased propulsive power and velocity that lead to a reduced jump height and landing force. Specific strength exercises that closely mimic sporting performance are more likely to optimise transference, therefore WR with light loads of 3-6% body mass (BM)appear a suitable tool for movement specific overload training and maximising transference to sporting performance. Practitioners can safely load their athletes with upper or lower body WR of 3-6% BM without fear of overloading the athletesover and above the landing forces they are typically accustomed too. As a training stimulus it would seem the WR loading provides adequate overload and athletes should focus on velocity of movement to improve power output and jump height i.e. take-off velocity.
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
2018-03-01
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 an iPhone app called 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 My Jump mobile application. 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, PJump, is an appropriate method to evaluate the vertical jump performance; however, vertical jump height is slightly overestimated compared with that of the force platform.
Model for polygonal hydraulic jumps
DEFF Research Database (Denmark)
Martens, Erik Andreas; Watanabe, Shinya; Bohr, Tomas
2012-01-01
We propose a phenomenological model for the polygonal hydraulic jumps discovered by Ellegaard and co-workers [Nature (London) 392, 767 (1998); Nonlinearity 12, 1 (1999); Physica B 228, 1 (1996)], based on the known flow structure for the type-II hydraulic jumps with a "roller" (separation eddy...... nonhydrostatic pressure contributions from surface tension in light of recent observations by Bush and co-workers [J. Fluid Mech. 558, 33 (2006); Phys. Fluids 16, S4 (2004)]. The model can be analyzed by linearization around the circular state, resulting in a parameter relationship for nearly circular polygonal...... states. A truncated but fully nonlinear version of the model can be solved analytically. This simpler model gives rise to polygonal shapes that are very similar to those observed in experiments, even though surface tension is neglected, and the condition for the existence of a polygon with N corners...
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.
Rantalainen, Timo; Gastin, Paul B; Spangler, Rhys; Wundersitz, Daniel
2018-09-01
The purpose of the present study was to evaluate the concurrent validity and test-retest repeatability of torso-worn IMU-derived power and jump height in a counter-movement jump test. Twenty-seven healthy recreationally active males (age, 21.9 [SD 2.0] y, height, 1.76 [0.7] m, mass, 73.7 [10.3] kg) wore an IMU and completed three counter-movement jumps a week apart. A force platform and a 3D motion analysis system were used to concurrently measure the jumps and subsequently derive power and jump height (based on take-off velocity and flight time). The IMU significantly overestimated power (mean difference = 7.3 W/kg; P jump heights exhibited poorer concurrent validity (ICC = 0.72 to 0.78) and repeatability (ICC = 0.68) than flight-time-derived jump heights, which exhibited excellent validity (ICC = 0.93 to 0.96) and reliability (ICC = 0.91). Since jump height and power are closely related, and flight-time-derived jump height exhibits excellent concurrent validity and reliability, flight-time-derived jump height could provide a more desirable measure compared to power when assessing athletic performance in a counter-movement jump with IMUs.
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. Copyright © 2016 Elsevier Ltd. All rights reserved.
Triple-root jump in spacecraft potential due to electron beam emission or impact
International Nuclear Information System (INIS)
Lai, S.T.
1992-01-01
Triple-root jump in spacecraft potential is well understood in the double Maxwellian model of the natural space environment. In this paper, however, the author points out that triple-root jumps in spacecraft potential may also occur during photoemission or electron beam emission from a spacecraft. Impact of an incoming electron beam on a spacecraft may also cause triple-root jumps provided that the beam, ambient plasma, and surface parameters satisfy certain inequality conditions. The parametric conditions under which such beam induced triple-root jumps may occur are presented
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.
Device for investigation of magnetic flux jumps in ribbon superconductors
International Nuclear Information System (INIS)
Andrianov, A.V.; Bashkirov, Yu.A.; Kremlev, M.G.
1986-01-01
A device for simulation of magnetic flux jumps in superconductors of conducting magnet sandwich-type windings super-applyed of a ribbon conductor is described. A superconducting magnet with a measuring cassetter are the main elements of the device. An external magnetic field is generated by a two-sectional superconducting magnet permitting to simulate the shape of the magnetic field characteristic for sandwich-type windings. Maximum radial component of the magnetic field is 2 T. Jumps of the magnetic flux are recorded by induction transducers and the magnetic field-by Hall trasducer. The effect of coating of standard metal on magnetic flux jumps in Nb 3 Sn base superconducting ribbon is considered
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(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. Copyright © 2015 Elsevier B.V. All rights reserved.
Wave structure in the radial film flow with a circular hydraulic jump
Energy Technology Data Exchange (ETDEWEB)
Rao, A.; Arakeri, J.H. [Indian Inst. of Science, Bangalore (India). Dept. of Mechanical Engineering
2001-11-01
A circular hydraulic jump is commonly seen when a circular liquid jet impinges on a horizontal plate. Measurements of the film thickness, jump radius and the wave structure for various jet Reynolds numbers are reported. Film thickness measurements are made using an electrical contact method for regions both upstream and downstream of the jump over circular plates without a barrier at the edge. The jump radius and the separation bubble length are measured for various flow rates, plate edge conditions, and radii. Flow visualization using high-speed photography is used to study wave structure and transition. Waves on the jet amplify in the film region upstream of the jump. At high flow rates, the waves amplify enough to cause three-dimensional breakdown and what seems like transition to turbulence. This surface wave induced transition is different from the traditional route and can be exploited to enhance heat and mass transfer rates. (orig.)
Loaded and unloaded jump performance of top-level volleyball players from different age categories.
Kitamura, Katia; Pereira, Lucas Adriano; Kobal, Ronaldo; Cal Abad, Cesar Cavinato; Finotti, Ronaldo; Nakamura, Fábio Yuzo; Loturco, Irineu
2017-09-01
The aim of this study was to investigate the differences in loaded and unloaded jump performances between different age categories of top-level volleyball players from the same club. Forty-three volleyball players were divided into four age groups: under-17, under-19, under-21 and professional. Vertical jumping height for squat jump (SJ), countermovement jump (CMJ) and CMJ with arm swing (CMJa) and mean propulsive velocity (MPV) in the loaded jump squat exercise with 40% of the athlete's body mass were compared among the different age categories, considering body mass as a covariate. SJ and CMJ jump height values were higher for professional and under-21 players than under-17 players (pjump squat was higher for under-21 players than under-17 players (pjump performances across different age categories of top-level volleyball players. Therefore, to increase the vertical jumping ability of these team sport athletes throughout their long-term development, coaches and strength and conditioning professionals are encouraged to implement consistent neuromuscular training strategies, in accordance with the specific needs and physiological characteristics of each age group.
Regime Jumps in Electricity Prices
R. Huisman (Ronald); R.J. Mahieu (Ronald)
2001-01-01
textabstractElectricity prices are known to be very volatile and subject to frequent jumps due to system breakdown, demand shocks, and inelastic supply. As many international electricity markets are in some state of deregulation, more and more participants in these markets are exposed to these
Validity of the Jump-and-Reach Test in Subelite Adolescent Handball Players.
Muehlbauer, Thomas; Pabst, Jan; Granacher, Urs; Büsch, Dirk
2017-05-01
Muehlbauer, T, Pabst, J, Granacher, U, and Büsch, D. Validity of the jump-and-reach test in subelite adolescent handball players. J Strength Cond Res 31(5): 1282-1289, 2017-The primary purpose of this study was to examine concurrent validity of the jump-and-reach (JaR) test using the Vertec system and a criterion device (i.e., Optojump system). In separate subanalyses, we investigated the influence of gym floor condition and athletes' sex on the validity of vertical jump height. Four hundred forty subelite adolescent female (n = 222, mean age: 14 ± 1 year, age range: 13-15 years) and male (n = 218, mean age: 15 ± 1 year, age range: 14-16 years) handball players performed the JaR test in gyms with region or point elastic floors. Maximal vertical jump height was simultaneously assessed using the Vertec and the Optojump systems. In general, significantly higher jump heights were obtained for the Vertec compared with the Optojump system (11.2 cm, Δ31%, Cohen's d = 2.58). The subanalyses revealed significantly larger jump heights for the Vertec compared with the Optojump system irrespective of gym floor condition and players' sex. The association between Optojump- and Vertec-derived vertical jump heights amounted to rP = 0.84, with a coefficient of determination (R) of 0.71. The subanalyses indicated significantly larger correlations in males (rP = 0.75, R = 0.56) than in females (rP = 0.63, R = 0.40). Yet, correlations were not significantly different between region (rP = 0.83, R = 0.69) as opposed to point elastic floor (rP = 0.87, R = 0.76). Our findings indicate that the 2 apparatuses cannot be used interchangeably. Consequently, gym floor and sex-specific regression equations were provided to estimate true (Optojump system) vertical jump height from Vertec-derived data.
Double the Fun with Two-Person, One-Rope Jump Rope
Heumann, Kristin J.; Murray, Steven Ross
2018-01-01
One popular activity within physical education curricula today is jump rope. Jump rope is recognized as an excellent activity for developing motor skills and the affective domain, and it aligns with several recommended outcomes for physical education listed by the SHAPE America--Society of Health and Physical Educators. This article describes…
Dynamics of force and muscle stimulation in human vertical jumping
Bobbert, M.F.; van Zandwijk, J.P.
1999-01-01
PURPOSE: The purpose of this study was to gain insight into the importance of stimulation dynamics for force development in human vertical jumping. METHODS: Maximum height squat jumps were performed by 21 male subjects. As a measure of signal dynamics, rise time (RT) was used, i.e., the time taken
EFFECT OF DIFFERENT STRETCHING PROTOCOLS ON VERTICAL JUMP PERFORMANCE
Directory of Open Access Journals (Sweden)
Emre Serin
2018-04-01
Full Text Available This study aimed to examine the effect of different stretching exercises on vertical jump performance. A total of 14 national male athletes sporting in the elite level took part in the study. The age average of the participants was 20.25±1.03 year, the average height was 1.80±.08 m, the average body weight was 77.14±18.91 kg, average of sporting age was 9.87±3.31 year and the average number of participation in international games was 10.0±3.31. As stretching protocol: Method 1 (5 minutes of jogging and 2 minutes of active rest followed by Method 2 (static stretching for 4 different muscle groups 3 repetitions for 15 seconds of static stretching, rest for 10 seconds between groups and then consecutively, Method 3 (Dynamic stretching exercises with 3 repetitions for 15 seconds and 10 seconds rest between different muscle groups were applied in the study. The vertical jump performance before and after different stretching exercises of the participants was determined by means of the vertical jump test using the smart speed lite system. Before and after the training of all athletes, HR was recorded with a heart rate monitor (RS 800, Polar Vantage NV, Polar Electro Oy, Finland with 5 seconds intervals. Before the study, the chest band of the heartbeat monitor was placed on the chest of the athlete and the HR was recorded from the monitor. SPSS 15.0 statistical package program was used for evaluation and calculation of the data. In this study in addition to descriptive statistics (mean and standard deviation paired samples t-test was used to determine the difference between the vertical jump performance of the participants before and after different stretching exercises. As a result, this study showed that; applying the dynamic and static stretching exercises consecutively affected the vertical jump performance 4.5 cm positively (p<.05. It is suggested that different dynamic and static stretching exercises should be included in the vertical jump.
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
Directory of Open Access Journals (Sweden)
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
Lightning Jump Algorithm Development for the GOES·R Geostationary Lightning Mapper
Schultz. E.; Schultz. C.; Chronis, T.; Stough, S.; Carey, L.; Calhoun, K.; Ortega, K.; Stano, G.; Cecil, D.; Bateman, M.;
2014-01-01
Current work on the lightning jump algorithm to be used in GOES-R Geostationary Lightning Mapper (GLM)'s data stream is multifaceted due to the intricate interplay between the storm tracking, GLM proxy data, and the performance of the lightning jump itself. This work outlines the progress of the last year, where analysis and performance of the lightning jump algorithm with automated storm tracking and GLM proxy data were assessed using over 700 storms from North Alabama. The cases analyzed coincide with previous semi-objective work performed using total lightning mapping array (LMA) measurements in Schultz et al. (2011). Analysis shows that key components of the algorithm (flash rate and sigma thresholds) have the greatest influence on the performance of the algorithm when validating using severe storm reports. Automated objective analysis using the GLM proxy data has shown probability of detection (POD) values around 60% with false alarm rates (FAR) around 73% using similar methodology to Schultz et al. (2011). However, when applying verification methods similar to those employed by the National Weather Service, POD values increase slightly (69%) and FAR values decrease (63%). The relationship between storm tracking and lightning jump has also been tested in a real-time framework at NSSL. This system includes fully automated tracking by radar alone, real-time LMA and radar observations and the lightning jump. Results indicate that the POD is strong at 65%. However, the FAR is significantly higher than in Schultz et al. (2011) (50-80% depending on various tracking/lightning jump parameters) when using storm reports for verification. Given known issues with Storm Data, the performance of the real-time jump algorithm is also being tested with high density radar and surface observations from the NSSL Severe Hazards Analysis & Verification Experiment (SHAVE).
Statistical Analysis of the First Passage Path Ensemble of Jump Processes
von Kleist, Max; Schütte, Christof; Zhang, Wei
2018-02-01
The transition mechanism of jump processes between two different subsets in state space reveals important dynamical information of the processes and therefore has attracted considerable attention in the past years. In this paper, we study the first passage path ensemble of both discrete-time and continuous-time jump processes on a finite state space. The main approach is to divide each first passage path into nonreactive and reactive segments and to study them separately. The analysis can be applied to jump processes which are non-ergodic, as well as continuous-time jump processes where the waiting time distributions are non-exponential. In the particular case that the jump processes are both Markovian and ergodic, our analysis elucidates the relations between the study of the first passage paths and the study of the transition paths in transition path theory. We provide algorithms to numerically compute statistics of the first passage path ensemble. The computational complexity of these algorithms scales with the complexity of solving a linear system, for which efficient methods are available. Several examples demonstrate the wide applicability of the derived results across research areas.
Technique of the biomechanical analysis of execution of upward jump piked
Directory of Open Access Journals (Sweden)
Nataliya Batieieva
2016-12-01
Full Text Available Purpose: the biomechanical analysis of execution of upward jump piked. Material & Methods: the following methods of the research were used: theoretical analysis and synthesis of data of special scientific and methodical literature; photographing, video filming, biomechanical computer analysis, pedagogical observation. Students (n=8 of the chair of national choreography of the department of choreographic art of Kiev national university of culture and art took part in carrying out the biomechanical analysis of execution of upward jump piked. Results: the biomechanical analysis of execution of upward jump piked is carried out, the kinematic characteristics (way, speed, acceleration, effort of the general center of weight (GCW and center of weight (CW of biolinks of body of the executor are received (feet, shins, hips, shoulder, forearm, hands. Biokinematic models (phases are constructed. Power characteristics are defined – mechanical work and kinetic energy of links of legs and hands at execution of upward jump piked. Conclusions: it is established that the technique of execution of upward jump piked considerably influences the level of technical training of the qualified sportsmen in gymnastics (sports, in aerobic gymnastics (aerobics, diving and dancing sports.
The effect of a secondary cognitive task on landing mechanics and jump performance.
Dai, Boyi; Cook, Ross F; Meyer, Elizabeth A; Sciascia, Yvonne; Hinshaw, Taylour J; Wang, Chaoyi; Zhu, Qin
2018-06-01
Anterior cruciate ligament (ACL) injuries commonly occur during jump-landing tasks when individuals' attention is simultaneously allocated to other objects and tasks. The purpose of the current study was to investigate the effect of allocation of attention imposed by a secondary cognitive task on landing mechanics and jump performance. Thirty-eight recreational athletes performed a jump-landing task in three conditions: no counting, counting backward by 1 s from a randomly given number, and counting backward by 7 s from a randomly given number. Three-dimensional kinematics and ground reaction forces were collected and analysed. Participants demonstrated decreased knee flexion angles at initial contact (p = 0.001) for the counting by 1 s condition compared with the no counting condition. Participants also showed increased peak posterior and vertical ground reaction forces during the first 100 ms of landing (p ≤ 0.023) and decreased jump height (p jump performance. ACL injury risk screening protocols and injury prevention programmes may incorporate cognitive tasks into jump-landing tasks to better simulate sports environments.
Take-off aerodynamics in ski jumping.
Virmavirta, M; Kivekäs, J; Komi, P V
2001-04-01
The effect of aerodynamic forces on the force-time characteristics of the simulated ski jumping take-off was examined in a wind tunnel. Vertical and horizontal ground reaction forces were recorded with a force plate installed under the wind tunnel floor. The jumpers performed take-offs in non-wind conditions and in various wind conditions (21-33 m s(-1)). EMGs of the important take-off muscles were recorded from one jumper. The dramatic decrease in take-off time found in all jumpers can be considered as the result of the influence of aerodynamic lift. The loss in impulse due to the shorter force production time with the same take-off force is compensated with the increase in lift force, resulting in a higher vertical velocity (V(v)) than is expected from the conventional calculation of V(v) from the force impulse. The wind conditions emphasized the explosiveness of the ski jumping take-off. The aerodynamic lift and drag forces which characterize the aerodynamic quality of the initial take-off position (static in-run position) varied widely even between the examined elite ski jumpers. According to the computer simulation these differences can decisively affect jumping distance. The proper utilization of the prevailing aerodynamic forces before and during take-off is a very important prerequisite for achieving a good flight position.
The Impact of Jump Distributions on the Implied Volatility of Variance
DEFF Research Database (Denmark)
Nicolato, Elisa; Pisani, Camilla; Pedersen, David Sloth
2017-01-01
We consider a tractable affine stochastic volatility model that generalizes the seminal Heston (1993) model by augmenting it with jumps in the instantaneous variance process. In this framework, we consider both realized variance options and VIX options, and we examine the impact of the distribution...... of jumps on the associated implied volatility smile. We provide sufficient conditions for the asymptotic behavior of the implied volatility of variance for small and large strikes. In particular, by selecting alternative jump distributions, we show that one can obtain fundamentally different shapes...
Self-adjoint Hamiltonians with a mass jump: General matching conditions
International Nuclear Information System (INIS)
Gadella, M.; Kuru, S.; Negro, J.
2007-01-01
The simplest position-dependent mass Hamiltonian in one dimension, where the mass has the form of a step function with a jump discontinuity at one point, is considered. The most general matching conditions at the jumping point for the solutions of the Schroedinger equation that provide a self-adjoint Hamiltonian are characterized
Effect of Ankle Joint Contact Angle and Ground Contact Time on Depth Jump Performance.
Phillips, Joshua H; Flanagan, Sean P
2015-11-01
Athletes often need to both jump high and get off the ground quickly, but getting off the ground quickly can decrease the vertical ground reaction force (VGRF) impulse, impeding jump height. Energy stored in the muscle-tendon complex during the stretch-shortening cycle (SSC) may mitigate the effects of short ground contact times (GCTs). To take advantage of the SSC, several coaches recommend "attacking" the ground with the foot in a dorsiflexed (DF) position at contact. However, the efficacy of this technique has not been tested. This investigation tested the hypotheses that shorter GCTs would lead to smaller vertical depth jump heights (VDJH), and that this difference could be mitigated by instructing the athletes to land in a DF as opposed to a plantar flexed (PF) foot position. Eighteen healthy junior college athletes performed depth jumps from a 45-cm box onto force platforms under instruction to achieve one of the 2 objectives (maximum jump height [hmax] or minimal GCT [tmin]), with one of the 2 foot conditions (DF or PF). These variations created 4 distinct jump conditions: DF-hmax, DF-tmin, PF-hmax, and PF-tmin. For all variables examined, there were no significant interactions. For all 4 conditions, the ankle was PF during landing, but the DF condition was 28.87% less PF than the PF condition. The tmin conditions had a 23.48% shorter GCT than hmax. There were no significant main effects for jump height. The peak impact force for tmin was 22.14% greater than hmax and 19.11% greater for DF compared with PF conditions. A shorter GCT did not necessitate a smaller jump height, and a less PF foot did not lead to improvements in jump height or contact time during a depth jump from a 45-cm box. The same jump height was attained in less PF and shorter GCT conditions by larger impact forces. To decrease contact time while maintaining jump height, athletes should be instructed to "get off the ground as fast as possible." This cue seems to be more important than foot
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...... differential forms in the case where A is the Jacobian of a curve C , and we give a compact explicit formula for the jumps in terms of the combinatorial reduction data of C. ...
The reliability of jump kinematics and kinetics in children of different maturity status.
Meylan, Cesar M P; Cronin, John B; Oliver, Jon L; Hughes, Michael G; McMaster, D Travis
2012-04-01
The purpose of this study was to determine the reliability of eccentric (ECC) and concentric (CON) kinematic and kinetic variables thought to be critical to jump performance during bilateral vertical countermovement jump (VCMJ) and horizontal countermovement jump (HCMJ) across children of different maturity status. Forty-two athletic male and female participants between 9 and 16 years of age were divided into 3 maturity groups according to peak height velocity (PHV) offset (Post-PHV, At-PHV, and Pre-PHV) and percent of predicted adult stature. All the participants performed 3 VCMJ and HCMJ trials and the kinematics, and kinetics of these jumps were measured via a force plate over 3 testing sessions. In both jumps, vertical CON mean and peak power and jump height or distance were the most reliable measures across all groups (change in the mean [CM] = -5.4 to 6.2%; coefficient of variation [CV] = 2.1-9.4%; Intraclass correlation coefficient [ICC] = 0.82-0.98), whereas vertical ECC mean power was the only ECC variable with acceptable reliability for both jumps (CM = -0.7 to 10.1%; CV = 5.2-15.6%; ICC = 0.74-0.97). A less mature state was "likely" to "very likely" to reduce the reliability of the HCMJ ECC kinetics and kinematics. These findings suggested that movement variability is associated with the ECC phase of CMJs, especially in Pre-PHV during the HCMJ. Vertical CON mean and peak power and ECC mean power were deemed reliable and appropriate to be used in children as indicators of jump and stretch-shortening cycle performance.
Giant flux jumps through a thin superconducting Nb film in a vortex free region
International Nuclear Information System (INIS)
Tsindlekht, M.I.; Genkin, V.M.; Felner, I.; Zeides, F.; Katz, N.; Gazi, Š.; Chromik, Š.
2016-01-01
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.
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.
Maffiuletti, N A; Cometti, G; Amiridis, I G; Martin, A; Pousson, M; Chatard, J C
2000-08-01
The aim of this study was to investigate the influence of a 4-week electromyostimulation training program on the strength of the knee extensors and the vertical jump performance of 10 basketball players. Electromyostimulation sessions were carried out 3 times weekly; each session consisted of 48 contractions. Testing was carried out before and after the electromyostimulation training program (week 4) and once more after 4 weeks of normal basketball training (week 8). At week 4, isokinetic strength increased significantly (p training increased also isometric strength at the two angles adjacent to the training angle (p jump increased significantly by 14% at week 4 (p jump showed no change. At week 8, gains in isokinetic, isometric strength and squat-jump performance were maintained and the counter movement jump performance increased significantly by 17% (ptraining program enhanced knee extensor strength and squat jump performance of basketball players.
Locomotion of Mexican jumping beans
International Nuclear Information System (INIS)
West, Daniel M; K Lal, Ishan; Leamy, Michael J; Hu, David L
2012-01-01
The Mexican jumping bean, Laspeyresia saltitans, consists of a hollow seed housing a moth larva. Heating by the sun induces movements by the larva which appear as rolls, jumps and flips by the bean. In this combined experimental, numerical and robotic study, we investigate this unique means of rolling locomotion. Time-lapse videography is used to record bean trajectories across a series of terrain types, including one-dimensional channels and planar surfaces of varying inclination. We find that the shell encumbers the larva's locomotion, decreasing its speed on flat surfaces by threefold. We also observe that the two-dimensional search algorithm of the bean resembles the run-and-tumble search of bacteria. We test this search algorithm using both an agent-based simulation and a wheeled Scribbler robot. The algorithm succeeds in propelling the robot away from regions of high temperature and may have application in biomimetic micro-scale navigation systems. (paper)
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.
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...
Stochastic representation of a class of non-Markovian completely positive evolutions
International Nuclear Information System (INIS)
Budini, Adrian A.
2004-01-01
By modeling the interaction of an open quantum system with its environment through a natural generalization of the classical concept of continuous time random walk, we derive and characterize a class of non-Markovian master equations whose solution is a completely positive map. The structure of these master equations is associated with a random renewal process where each event consist in the application of a superoperator over a density matrix. Strong nonexponential decay arise by choosing different statistics of the renewal process. As examples we analyze the stochastic and averaged dynamics of simple systems that admit an analytical solution. The problem of positivity in quantum master equations induced by memory effects [S. M. Barnett and S. Stenholm, Phys. Rev. A 64, 033808 (2001)] is clarified in this context
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......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 controlled in real-time by pro- cessing the signal captured by a contact microphone which was attached to the membrane of the trampoline in order to detect each jump. A user study was conducted to evaluate the quality of the in- teractive sonification. Results proved the success of the proposed algorithms...
DEFF Research Database (Denmark)
Hébert-Losier, Kim; Jensen, Kurt; Holmberg, Hans-Christer
2014-01-01
PURPOSE: Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlatio...... and rapid generation of high relative maximal forces, especially vertically. These functional measures were more closely related to sprinting and/or running abilities, indicating benefits of lower-body training in orienteering.......PURPOSE: Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlations...... with sprinting and/or running have been examined in orienteering athletes. METHODS: We investigated squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), and hopping performed by 8 elite and 8 amateur male foot-orienteering athletes (29 ± 7 y, 183 ± 5 cm, 73 ± 7 kg) and possible correlations...
Effect of Parachute Jump in the Psychophysiological Response of Soldiers in Urban Combat.
Sánchez-Molina, Joaquín; Robles-Pérez, José J; Clemente-Suárez, Vicente J
2017-06-01
The study of organic and psychological response during combat situations has been poorly reported despite its importance for soldiers training and specific instruction, so it was proposed as aim of the present investigation to analyze the effect of a tactical parachute simulated jump in psycho-physiological response of paratroopers' warfighters during an urban combat simulation. 19 male paratroopers (31.9 ± 6.2 year old; 173.6 ± 5.3 cm; 73.8 ± 8.3 Kg) of the Spanish Army were divided in two groups: parachute jump group (n:11) that conducted a simulated parachute jump and a urban combat maneuver and a non-parachute jump group (n:8) that only conducted an urban combat maneuver. We analyzed before and after the maneuver the rated perceived exertion, legs strength manifestation, blood lactate, cortical activation, heart rate variability, blood oxygen saturation and pressure, skin temperature, fine motor skills, and anxiety state. A tactical parachute simulated jump prior to an urban combat maneuver produce significantly (p jump situation in professional Army paratroopers. Independently of the parachute jump, an urban combat maneuver produces a significant increase in rated perceived exertion, blood lactate, heart rate, legs strength, sympathetic modulation and anxiety response as well as a significant decrease in blood oxygen saturation and parasympathetic modulation.
Judge, L W; Burke, J R
2015-06-01
The purpose of the study was to describe changes in the excitability of the stretch reflex response (SRR) during different drop jumps as a function of training background and as an adaptation to a preseason sport-specific resistance training program. Twelve collegiate field event athletes (discus, hammer, javelin, shot put, and weight; 9 males and 3 females) and 12 college-aged control subjects performed the following three jumps: (1) countermovement jump (CMJ); (2) countermovement drop jump; and (3) bounce-drop jump (BDJ). Neuromechanical changes in the performance of drop jumps by athletes were measured during the sport-specific resistance training program. Pre-post testing of drop jump performance by control subjects was included for comparison. For each jump trial, ground reaction forces (GRF), electromyograms (EMG) and cinematographic data were collected. There were no training adaptations. However, jump heights were greater for the athletes than the controls among the different jumps with the jump heights for all subjects being less during the BDJ than CMJ and CDJ. In athletes only, there was a differential modulation of the SRR from the gastrocnemius muscle with different levels of background muscle activity for the CDJ and BDJ. There were changes in excitability of SRR from the gastrocnemius muscle as a function of training background. Interrelated neuromechanical mechanisms to include landing biomechanics, intrinsic musculotendinous tissue properties of the ankle, and centrally regulated motor commands may underlie the facilitation of the SRR from the gastrocnemius muscle in athletes as compared to controls.
Alterations of Vertical Jump Mechanics after a Half-Marathon Mountain Running Race.
Rousanoglou, Elissavet N; Noutsos, Konstantinos; Pappas, Achilleas; Bogdanis, Gregory; Vagenas, Georgios; Bayios, Ioannis A; Boudolos, Konstantinos D
2016-06-01
The fatiguing effect of long-distance running has been examined in the context of a variety of parameters. However, there is scarcity of data regarding its effect on the vertical jump mechanics. The purpose of this study was to investigate the alterations of countermovement jump (CMJ) mechanics after a half-marathon mountain race. Twenty-seven runners performed CMJs before the race (Pre), immediately after the race (Post 1) and five minutes after Post 1 (Post 2). Instantaneous and ensemble-average analysis focused on jump height and, the maximum peaks and time-to-maximum peaks of: Displacement, vertical force (Fz), anterior-posterior force (Fx), Velocity and Power, in the eccentric (tECC) and concentric (tCON) phase of the jump, respectively. Repeated measures ANOVAs were used for statistical analysis (p ≤ 0.05). The jump height decrease was significant in Post 2 (-7.9%) but not in Post 1 (-4.1%). Fx and Velocity decreased significantly in both Post 1 (only in tECC) and Post 2 (both tECC and tCON). Α timing shift of the Fz peaks (earlier during tECC and later during tCON) and altered relative peak times (only in tECC) were also observed. Ensemble-average analysis revealed several time intervals of significant post-race alterations and a timing shift in the Fz-Velocity loop. An overall trend of lowered post-race jump output and mechanics was characterised by altered jump timing, restricted anterior-posterior movement and altered force-velocity relations. The specificity of mountain running fatigue to eccentric muscle work, appears to be reflected in the different time order of the post-race reductions, with the eccentric phase reductions preceding those of the concentric one. Thus, those who engage in mountain running should particularly consider downhill training to optimise eccentric muscular action. Key pointsThe 4.1% reduction of jump height immediately after the race is not statistically significantThe eccentric phase alterations of jump mechanics precede
The prevalence of ski jumping among pupils in the first triad of primary school
Vtič, Maja
2016-01-01
As one of the most widespread sports discipline in Slovenia, ski jumping has a long tradition. Ski jumping is a competitive sport at which recreational engagement is not possible because of its special features and specifics. It is one of the basic sports activities for the development of children's motor skills, since ski jumping requires an integrated training of the trainee. Ski jumping is basically a winter sport, whereas in the summer season, it has also become increasingly present with ...
The “Suicide Guard Rail”: a minimal structural intervention in hospitals reduces suicide jumps
Mohl, Andreas; Stulz, Niklaus; Martin, Andrea; Eigenmann, Franz; Hepp, Urs; Hüsler, Jürg; Beer, Jürg H
2012-01-01
Abstract Background Jumping from heights is a readily available and lethal method of suicide. This study examined the effectiveness of a minimal structural intervention in preventing suicide jumps at a Swiss general teaching hospital. Following a series of suicide jumps out of the hospital’s windows, a metal guard rail was installed at each window of the high-rise building. Results In the 114 months prior to the installation of the metal guard rail, 10 suicides by jumping out of the hospital’...
The identification of price jumps
Czech Academy of Sciences Publication Activity Database
Hanousek, Jan; Kočenda, Evžen; Novotný, Jan
2012-01-01
Roč. 18, č. 1 (2012), s. 53-77 ISSN 0929-9629 R&D Projects: GA ČR(CZ) GAP403/11/0020; GA ČR(CZ) GBP402/12/G097 Institutional support: PRVOUK-P23 Keywords : price jumps * non-parametric testing * financial econometrics Subject RIV: AH - Economics
Entanglement and Zeeman interaction in diluted magnetic semiconductor quantum dot
International Nuclear Information System (INIS)
Hichri, A.; Jaziri, S.
2004-01-01
We present theoretically the Zeeman coupling and exchange-induced swap action in spin-based quantum dot quantum computer models in the presence of magnetic field. We study the valence and conduction band states in a double quantum dots made in diluted magnetic semiconductor. The latter have been proven to be very useful in building an all-semiconductor platform for spintronics. Due to a strong p-d exchange interaction in diluted magnetic semiconductor (Cd 0.57 Mn 0.43 Te), the relative contribution of this component is strongly affected by an external magnetic field, a feature that is absent in nonmagnetic double quantum dots. We determine the energy spectrum as a function of magnetic field within the Hund-Mulliken molecular-orbit approach and by including the Coulomb interaction. Since we show that the ground state of the two carriers confined in a vertically coupled quantum dots provide a possible realization for a gate of a quantum computer, the crossing between the lowest states, caused by the giant spin splitting, can be observed as a pronounced jump in the magnetization of small magnetic field amplitude. Finally, we determine the swap time as a function of magnetic field and the inter dot distance. We estimate quantitatively swap errors caused by the field, establishing that error correction would, in principle, be possible in the presence of nonuniform magnetic field in realistic structures
Jump Telegraph Processes and Financial Markets with Memory
Directory of Open Access Journals (Sweden)
Nikita Ratanov
2007-01-01
Full Text Available The paper develops a new class of financial market models. These models are based on generalized telegraph processes with alternating velocities and jumps occurring at switching velocities. The model under consideration is arbitrage-free and complete if the directions of jumps in stock prices are in a certain correspondence with their velocity and with the behaviour of the interest rate. A risk-neutral measure and arbitrage-free formulae for a standard call option are constructed. This model has some features of models with memory, but it is more simple.
The “Suicide Guard Rail”: a minimal structural intervention in hospitals reduces suicide jumps
Directory of Open Access Journals (Sweden)
Mohl Andreas
2012-08-01
Full Text Available Abstract Background Jumping from heights is a readily available and lethal method of suicide. This study examined the effectiveness of a minimal structural intervention in preventing suicide jumps at a Swiss general teaching hospital. Following a series of suicide jumps out of the hospital’s windows, a metal guard rail was installed at each window of the high-rise building. Results In the 114 months prior to the installation of the metal guard rail, 10 suicides by jumping out of the hospital’s windows occurred among 119,269 inpatients. This figure was significantly reduced to 2 fatal incidents among 104,435 inpatients treated during the 78 months immediately following the installation of the rails at the hospital’s windows (χ2 = 4.34, df = 1, p = .037. Conclusions Even a minimal structural intervention might prevent suicide jumps in a general hospital. Further work is needed to examine the effectiveness of minimal structural interventions in preventing suicide jumps.
Moderation of flux jumps dynamics by eddy-currents in a disk shape NbTi superconductor
International Nuclear Information System (INIS)
Vasiliev, S.; Nabialek, A.; Piechota, S.; Szymczak, H.; Chabanenko, V.V.; Rusakov, V.
2004-01-01
We studied the moderation of the flux jumps dynamics in a disc shape NbTi-50% superconductor caused by eddy-currents induced in two copper cylinders attached to both surfaces of the investigated sample. We investigated experimentally the time of the flux jump duration, amount of the magnetic flux entering the sample during the jump as well as the sine structure of the jumps as a function of temperature and the external magnetic field. A simple theoretical model, which describes the magnetic field dependence of the amount of the magnetic flux entering the superconducting sample during the flux jump, was developed. (author)
Sign realized jump risk and the cross-section of stock returns: Evidence from China's stock market.
Chao, Youcong; Liu, Xiaoqun; Guo, Shijun
2017-01-01
Using 5-minute high frequency data from the Chinese stock market, we employ a non-parametric method to estimate Fama-French portfolio realized jumps and investigate whether the estimated positive, negative and sign realized jumps could forecast or explain the cross-sectional stock returns. The Fama-MacBeth regression results show that not only have the realized jump components and the continuous volatility been compensated with risk premium, but also that the negative jump risk, the positive jump risk and the sign jump risk, to some extent, could explain the return of the stock portfolios. Therefore, we should pay high attention to the downside tail risk and the upside tail risk.
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.
THE RELATIONS BETWEEN MORPHOLOGICAL SPACE AND THE ATHLETES’ JUMPING AND THROWING EVENTS RESULT
Directory of Open Access Journals (Sweden)
Igor Stanojević
2014-12-01
Full Text Available The sample included 200 primary school students in the region of Prokuplje, male, aged 13 and 14 years, who, in addition to regular physical education classes, were included in the sports clubs training activities. The variables sample included 13 anthropometric measures as a set of predictors and four specific-motor tests of jumping (high jump and long jump and throwing events (shot put and javelin, as well as a set of criteria. The aim of this research was to examine the relation of morphological characteristics with the jumping and throwing events results, with elementary school students as athletes. Determining the relations and influence between the morphological characteristics and the specific motor skills was obtained by applying the canonical-correlation and regression analysis. The research of canonical correlation analysis results showed that there are statistically significant interlinks between canonical factors of morphological dimension Can. 0.81% (p = .000 and the results of examinee’s specific-motor skills in a long running jump, running high jump, shot put and javelin. Regression analysis results show that the morphological dimensions have an important prediction of the results of examinee’s specific-motor skills.
Effect of a submaximal half-squats warm-up program on vertical jumping ability.
Gourgoulis, Vassilios; Aggeloussis, Nickos; Kasimatis, Panagiotis; Mavromatis, Giorgos; Garas, Athanasios
2003-05-01
The purpose of the current research was to study the effect of a warm-up program including submaximal half-squats on vertical jumping ability. Twenty physically active men participated in the study. Each subject performed 5 sets of half-squats with 2 repetitions at each of the following intensities: 20, 40, 60, 80, and 90% of the 1 repetition maximum (1RM) load. Prior to the first set and immediately after the end of the last set, the subjects performed 2 countermovement jumps on a Kistler force platform; the primary goal was to jump as high as possible. The results showed that mean vertical jumping ability improved by 2.39% after the warm-up period. Subjects were then divided into 2 groups according to their 1RM values for the half-squat. Subjects with greater maximal strength ability improved their vertical jumping ability (4.01%) more than did subjects with lower maximal strength (0.42%). A warm-up protocol including half-squats with submaximal loads and explosive execution can be used for short-term improvements of vertical jumping performance, and this effect is greater in athletes with a relatively high strength ability.
Orientational dynamics in a room temperature ionic liquid: Are angular jumps predominant?
Das, Suman; Mukherjee, Biswaroop; Biswas, Ranjit
2018-05-01
Reorientational dynamics of the constituent ions in a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]), are explored via molecular dynamics simulations, and several features of orientation dynamics are summarized. The anion, [PF6]-, not only exhibits a higher propensity to orientation jumps than the cation, [BMIM]+ but also accesses a wider jump angle distribution and larger peak-angle. Jump and waiting time distributions for both the ions depict power-law dependences, suggesting temporally heterogeneous dynamics for the medium. This heterogeneity feature is further highlighted by the finding that the simulated first rank (ℓ = 1) and second rank (ℓ = 2) average reorientational correlation times reflect a severe break-down of Debye's ℓ(ℓ + 1) law for orientational diffusion in an isotropic homogeneous medium. Simulated average H-bond lifetime resides between the mean orientation jump and waiting times, while the structural H-bond relaxation suggests, as in normal liquids, a pronounced presence of translational motion of the partnering ions. Average simulated jump trajectories reveal a strong rotation-translation coupling and indicate relatively larger changes in spatial and angular arrangements for the anion during an orientation jump. In fact, a closer inspection of all these results points toward more heterogeneous dynamics for [PF6]- than [BMIM]+. This is a new observation and may simply be linked to the ion-size. However, such a generalization warrants further study.
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.
Pricing Vulnerable Options with Market Prices of Common Jump Risks under Regime-Switching Models
Directory of Open Access Journals (Sweden)
Miao Han
2018-01-01
Full Text Available This paper investigates the valuation of vulnerable European options considering the market prices of common systematic jump risks under regime-switching jump-diffusion models. The way of regime-switching Esscher transform is adopted to identify an equivalent martingale measure for pricing vulnerable European options. Explicit analytical pricing formulae for vulnerable European options are derived by risk-neutral pricing theory. For comparison, the other two cases are also considered separately. The first case considers all jump risks as unsystematic risks while the second one assumes all jumps risks to be systematic risks. Numerical examples for the valuation of vulnerable European options are provided to illustrate our results and indicate the influence of the market prices of jump risks on the valuation of vulnerable European options.
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 < 0.05). Results indicated that force and time variables increased as drop jump height increased (p < 0.0001). Post hoc analyses showed that at 0.2- and 0.4-m bilateral differences were present in the time to peak force, average force, and impulse. No bilateral differences for any variables were shown at 0.6-m starting height. The contact time for all jumps was <0.26 seconds. At 0.2 m, only 63% of the subjects had a starting time differential of <0.01 seconds, rising to 96.3% at 0.6 m. The results indicated that 0.6 m is the suggested drop jump height to ensure that no bilateral differences in vertical forces and temporal components occur; however, shorter contact times were found at the lower heights.
Directory of Open Access Journals (Sweden)
Joanna Mazur-Różycka
2017-07-01
Full Text Available The aim of the study was to compare selected biomechanical parameters obtained during various types of vertical jumps made by volleyball and basketball players on a dynamometric platform. The study involved 10 volleyball players and 10 basketball players in the age of 21.1 ± 1.81 years of the AZS AWF Warsaw sport club. The athletes performed two vertical jumps on a KISTLER platform. The first jump was a counter-movement jump (CMJ and the second was a spike jump (SPJ – a vertical jump which is performed with a 3-4 step run-up before the take-off. The participant's task was to take off and land on the platform. On the basis of the statistical analysis it was shown that only the type of jump had a significant effect on the height and power. The type of team sport did not affect the level of performance. In addition, it was found that the height of the jump is affected by the counter movement phase with hand swing and run-up. The volleyball and basketball players were equally able to get higher values for certain parameters in successive runs. Due to lack of statistically significant differences it was decided to combine two groups of athletes into one. For both jumps, the relationship between peak power and jump height was found at significance level p <0.001. Dynamometric platform can be used to check the athlete's height of jump and power of lower extremities. This method allows to verify the effectiveness of different types of training.
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
Directory of Open Access Journals (Sweden)
Cale Bechtel
2018-01-01
Full Text Available Background: Back squats (BSQ have been shown to transiently improve performance in explosive vertical movements such as the vertical jump (VJ. Still, understanding of this phenomenon, termed post-activation potentiation (PAP, remains nebulous as it relates to explosive horizontal movements. Objective: Therefore, the purpose of the present investigation was to assess whether heavy BSQ can potentiate both VJ and horizontal jump (HJ performance. Method: Nine male ice hockey players from the Long Beach State ice hockey team performed five testing sessions separated by 96-hours. The first testing session consisted of a one repetition maximum (1-RM BSQ to determine subsequent testing loads. The four subsequent testing sessions, which were randomized for order, consisted of five repetitions of BSQ at 87% 1-RM followed by horizontal jump (BSQ-HJ, five repetitions of BSQ at 87% 1-RM followed by vertical jump (BSQ-VJ, horizontal jump only (CT-HJ and vertical jump only (CT-VJ. During the potentiated conditions, rest intervals were set at five minutes between the BSQ and either VJ or HJ. Alpha-level was set a priori at 0.05. Results: The results indicate that both vertical (p=0.017 and horizontal (p=0.003 jump were significantly increased (VJ= +5.51cm, HJ= +11.55cm following a BSQ. Conclusion: These findings suggest that BSQ may improve both vertical and horizontal jump performance in athletes who participate in sports emphasizing horizontal power, such as ice hockey.
Principal component structure and sport-specific differences in the running one-leg vertical jump.
Laffaye, G; Bardy, B G; Durey, A
2007-05-01
The aim of this study is to identify the kinetic principal components involved in one-leg running vertical jumps, as well as the potential differences between specialists from different sports. The sample was composed of 25 regional skilled athletes who play different jumping sports (volleyball players, handball players, basketball players, high jumpers and novices), who performed a running one-leg jump. A principal component analysis was performed on the data obtained from the 200 tested jumps in order to identify the principal components summarizing the six variables extracted from the force-time curve. Two principal components including six variables accounted for 78 % of the variance in jump height. Running one-leg vertical jump performance was predicted by a temporal component (that brings together impulse time, eccentric time and vertical displacement of the center of mass) and a force component (who brings together relative peak of force and power, and rate of force development). A comparison made among athletes revealed a temporal-prevailing profile for volleyball players, and a force-dominant profile for Fosbury high jumpers. Novices showed an ineffective utilization of the force component, while handball and basketball players showed heterogeneous and neutral component profiles. Participants will use a jumping strategy in which variables related to either the magnitude or timing of force production will be closely coupled; athletes from different sporting backgrounds will use a jumping strategy that reflects the inherent demands of their chosen sport.
Stochastic stability of mechanical systems under renewal jump process parametric excitation
DEFF Research Database (Denmark)
Iwankiewicz, R.; Nielsen, Søren R.K.; Larsen, Jesper Winther
2005-01-01
A dynamic system under parametric excitation in the form of a non-Erlang renewal jump process is considered. The excitation is a random train of nonoverlapping rectangular pulses with equal, deterministic heights. The time intervals between two consecutive jumps up (or down), are the sum of two...
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...
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.
Hypohydration Reduces Vertical Ground Reaction Impulse But Not Jump Height
2010-01-01
height, provided that muscle contractile function remains normal, because gravitational and inertial resistance to jumping are pro- portional to body...testing, anthropometric and fitness measurements were made to characterize the study population. Peak aerobic power (VO2peak) was determined using an...determinations. All volunteers performed between 3 and 5 practice days of vertical jump testing to reduce training and learning effects. Practice
Shock-jump conditions in a general medium: weak-solution approach
Forbes, L. K.; Krzysik, O. A.
2017-05-01
General conservation laws are considered, and the concept of a weak solution is extended to the case of an equation involving three space variables and time. Four-dimensional vector calculus is used to develop general jump conditions at a shock wave in the material. To illustrate the use of this result, jump conditions at a shock in unsteady three-dimensional compressible gas flow are presented. It is then proved rigorously that these reduce to the commonly assumed conditions in coordinates normal and tangential to the shock face. A similar calculation is also outlined for an unsteady three-dimensional shock in magnetohydrodynamics, and in a chemically reactive fluid. The technique is available for determining shock-jump conditions in quite general continuous media.
The Effect of Teeth Clenching on Dynamic Balance at Jump-Landing: A Pilot Study.
Nakamura, Tomomasa; Yoshida, Yuriko; Churei, Hiroshi; Aizawa, Junya; Hirohata, Kenji; Ohmi, Takehiro; Ohji, Shunsuke; Takahashi, Toshiyuki; Enomoto, Mitsuhiro; Ueno, Toshiaki; Yagishita, Kazuyoshi
2017-07-01
The aim of this study was to analyze the effect of teeth clenching on dynamic balance at jump landing. Twenty-five healthy subjects performed jump-landing tasks with or without teeth clenching. The first 3 trials were performed with no instruction; subsequently, subjects were ordered to clench at the time of landing in the following 3 trials. We collected the data of masseter muscle activity by electromyogram, the maximum vertical ground reaction force (vGRFmax) and center of pressure (CoP) parameters by force plate during jump-landing. According to the clenching status of control jump-landing, all participants were categorized into a spontaneous clenching group and no clenching group, and the CoP data were compared. The masseter muscle activity was correlated with vGRFmax during anterior jump-landing, while it was not correlated with CoP. In comparisons between the spontaneous clenching and the no clenching group during anterior jump-landing, the spontaneous clenching group showed harder landing and the CoP area became larger than the no clenching group. There were no significant differences between pre- and postintervention in both spontaneous clenching and no clenching groups. The effect of teeth clenching on dynamic balance during jump-landing was limited.
Bartmann, W; Métral, E; Möhl, D; Peggs, S
2008-01-01
The PS2, which is proposed as a replacement for the existing ~50-year old PS accelerator, is presently considered to be a normal conducting synchrotron with an injection kinetic energy of 4 GeV and a maximum energy of 50 GeV. One of the possible lattices (FODO option) foresees crossing of transition energy near 10 GeV. Since the phase-slip-factor $\\eta$ becomes very small near transition energy, many intensity dependent effects can take place in both longitudinal and transverse planes. The aim of the present paper is on the one hand to scale the gamma transition jump, used since 1973 in the PS, to the projected PS2 and on the other hand based on these results the analysis of the implementation and feasibility of a gamma transition jump scheme in a conventional FODO lattice.
Birth-jump processes and application to forest fire spotting.
Hillen, T; Greese, B; Martin, J; de Vries, G
2015-01-01
Birth-jump models are designed to describe population models for which growth and spatial spread cannot be decoupled. A birth-jump model is a nonlinear integro-differential equation. We present two different derivations of this equation, one based on a random walk approach and the other based on a two-compartmental reaction-diffusion model. In the case that the redistribution kernels are highly concentrated, we show that the integro-differential equation can be approximated by a reaction-diffusion equation, in which the proliferation rate contributes to both the diffusion term and the reaction term. We completely solve the corresponding critical domain size problem and the minimal wave speed problem. Birth-jump models can be applied in many areas in mathematical biology. We highlight an application of our results in the context of forest fire spread through spotting. We show that spotting increases the invasion speed of a forest fire front.
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.
Abdominal muscle activity during a standing long jump.
Okubo, Yu; Kaneoka, Koji; Shiina, Itsuo; Tatsumura, Masaki; Miyakawa, Shumpei
2013-08-01
Experimental laboratory study. To measure the activation patterns (onset and magnitude) of the abdominal muscles during a standing long jump using wire and surface electromyography. Activation patterns of the abdominal muscles, especially the deep muscles such as the transversus abdominis (TrA), have yet to be examined during full-body movements such as jumping. Thirteen healthy men participated. Wire electrodes were inserted into the TrA with the guidance of ultrasonography, and surface electrodes were attached to the skin overlying the rectus abdominis (RA) and external oblique (EO). Electromyographic signals and video images were recorded while each subject performed a standing long jump. The jump task was divided into 3 phases: preparation, push-off, and float. For each muscle, activation onset relative to the onset of the RA and normalized muscle activation levels (percent maximum voluntary contraction) were analyzed during each phase. Comparisons between muscles and phases were assessed using 2-way analyses of variance. The onset times of the TrA and EO relative to the onset of the RA were -0.13 ? 0.17 seconds and -0.02 ? 0.07 seconds, respectively. Onset of TrA activation was earlier than that of the EO. The activation levels of all 3 muscles were significantly greater during the push-off phase than during the preparation and float phases. Consistent with previously published trunk-perturbation studies in healthy persons, the TrA was activated prior to the RA and EO. Additionally, the highest muscle activation levels were observed during the push-off phase.
Changes in Jump-Down Performance After Space Flight: Short- and Long-Term Adaptation
Kofman, I. S.; Reschke, M. F.; Cerisano, J. M.; Fisher, E. A.; Lawrence, E. L.; Peters, B. T.; Bloomberg, J. J.
2010-01-01
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 the jump strategies used by astronauts before and after flight, the changes to those strategies within a test session, and the 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 Six 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. A force plate measured the ground reaction forces and center-of-pressure displacement from the landings. Muscle 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 AND CONCLUSION Many of the astronauts tested were unable to maintain balance on their first postflight jump landing but recovered by the third jump, showing a learning progression in which the performance improvement could be attributed to adjustments of strategy on takeoff, landing, or both. Takeoff strategy changes were evident in air time (time between takeoff and landing), which was significantly reduced after flight, and also in increased asymmetry in foot latencies on takeoff. Landing modifications were seen in changes in ground reaction force curves. The
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.
Kinematic Analysis of the Standing Long Jump in Children 6- to 12-Years-Old
Fernandez-Santos, Jorge R.; Gonzalez-Montesinos, Jose Luis; Ruiz, Jonatan R.; Jiménez-Pavón, David; Castro-Piñero, Jose
2018-01-01
The purpose of this study was to analyze the kinematic variables that determine the performance of the standing long jump in children 6- to 12-years-old. There were 121 healthy children (58 girls) recorded while they performed the standing long jump test. All kinematic variables showed a significant correlation with calculated jump distance and…
Influence of sports flooring and shoes on impact forces and performance during jump tasks.
Malisoux, Laurent; Gette, Paul; Urhausen, Axel; Bomfim, Joao; Theisen, Daniel
2017-01-01
We aim to determine the influence of sports floorings and sports shoes on impact mechanics and performance during standardised jump tasks. Twenty-one male volunteers performed ankle jumps (four consecutive maximal bounds with very dynamic ankle movements) and multi-jumps (two consecutive maximal counter-movement jumps) on force plates using minimalist and cushioned shoes under 5 sports flooring (SF) conditions. The shock absorption properties of the SF, defined as the proportion of peak impact force absorbed by the tested flooring when compared with a concrete hard surface, were: SF0 = 0% (no flooring), SF1 = 19%, SF2 = 26%, SF3 = 37% and SF4 = 45%. Shoe and flooring effects were compared using 2x5 repeated-measures ANOVA with post-hoc Bonferroni-corrected comparisons. A significant interaction between SF and shoe conditions was found for VILR only (p = 0.003). In minimalist shoes, SF influenced Vertical Instantaneous Loading Rate (VILR) during ankle jumps (p = 0.006) and multi-jumps (pflooring. VILR is the variable that was the most affected.
Rashiti Naser; Ajvazi Vlora; Adem Nura; Fadil Nika
2011-01-01
In order to examine the impact of anthropometrical characteristics and motor skills during the tests’ implementation of the jump forward and triple jump from place, the experimental research was carried out on a sample of 100 second year students from the Faculty of Physical Education and Sport in Prishtine. For the purposes of this study were measured eight anthropometrical characteristics and ten tests for assessing motor skills, which made the predictor system of variables. To assess the e...
European Option Pricing with Transaction Costs in Lévy Jump Environment
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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.
Gaze Strategies in Skateboard Trick Jumps: Spatiotemporal Constraints in Complex Locomotion
Klostermann, André; Küng, Philip
2017-01-01
Purpose: This study aimed to further the knowledge on gaze behavior in locomotion by studying gaze strategies in skateboard jumps of different difficulty that had to be performed either with or without an obstacle. Method: Nine experienced skateboarders performed "Ollie" and "Kickflip" jumps either over an obstacle or over a…
Seasonal differences in jump performance in the Svalbard rock ptarmigan (Lagopus muta hyperborea
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John J. Lees
2014-07-01
Full Text Available Fat storage is essential to the survival of many bird species, providing energy reserves, but can have an effect on locomotor performance with an associated potential increase in predation risk. In particular, the ability to initiate flight through jumping is critical to predator avoidance and may be influenced by changes in body mass (Mb. Here we investigate seasonal differences in the jump take-off performance of high Arctic Svalbard rock ptarmigan (Lagopus muta hyperborea resulting from around a 50% increase in Mb during winter as a result of fat deposition. Using force-plate data and videography, we reveal that, in the absence of alterations to take-off angle, winter Svalbard rock ptarmigan are unable to increase hind-limb power output during jumping to compensate for their increased Mb. As a result, peak take-off velocity is reduced by 42% and jump duration is also extended during winter. The consequences of reduced jumping performance upon Svalbard ptarmigan during winter may be relatively small given their low risk of predation during this season. It may be, however, that the observed reduction in jumping performance when fat may contribute to the sub-maximal pattern of fat acquisition observed in other bird species.
How do elite ski jumpers handle the dynamic conditions in imitation jumps?
Ettema, Gertjan; Hooiveld, Jo; Braaten, Steinar; Bobbert, Maarten
2016-01-01
We examined the effect of boundary conditions in imitation ski jumping on movement dynamics and coordination. We compared imitation ski jumps with--and without--the possibility to generate shear propulsion forces. Six elite ski jumpers performed imitation jumps by jumping from a fixed surface and from a rolling platform. The ground reaction force vector, kinematics of body segments, and EMG of eight lower limb muscles were recorded. Net joint dynamics were calculated using inverse dynamics. The two imitation jumps differed considerably from each other with regard to the dynamics (moments, forces), whereas the kinematics were very similar. Knee power was higher and hip power was lower on the rolling platform than on the fixed surface. Mean EMG levels were very similar for both conditions, but differences in the development of muscle activity were indicated for seven of eight muscles. These differences are reflected in a subtle difference of the alignment of ground reaction force with centre of mass: the ground reaction force runs continuously close to but behind the centre of mass on the rolling platform and fluctuates around it on the fixed surface. This likely reflects a different strategy for controlling angular momentum.
Characteristics of the early flight phase in the Olympic ski jumping competition.
Virmavirta, Mikko; Isolehto, Juha; Komi, Paavo; Brüggemann, Gert-Peter; Müller, Erich; Schwameder, Hermann
2005-11-01
Early flight phase (approximately 40 m) of the athletes participating in the final round of the individual large hill ski jumping competition in Salt Lake City Olympics was filmed with two high-speed pan & tilt video cameras. The results showed that jumpers' steady flight position was almost completed within 0.5s. The most significant correlation with the length of the jump was found in the angle between the skis and body (r=.714, p.001 at 1.1s after the take-off). This particular phase seemed to be important because the ski angle of attack was also related to the jumping distance at the same phase. Although the more upright ski position relative to flight path resulted in longer jumping distance, the winner of the competition had significantly lower ski position as compared to the other good jumpers. This may be due to the high altitude (>2000 m) of the ski jumping stadium in this competition. Because of the low air density, the aerodynamic forces were also low and this probably caused less skillful jumpers to lean too much forward at this phase. Maintenance of speed seemed to be emphasized in this particular competition.
Rebutini, Vanessa Z; Pereira, Gleber; Bohrer, Roberta C D; Ugrinowitsch, Carlos; Rodacki, André L F
2016-09-01
Rebutini, VZ, Pereira, G, Bohrer, RCD, Ugrinowitsch, C, and Rodacki, ALF. Plyometric long jump training with progressive loading improves kinetic and kinematic swimming start parameters. J Strength Cond Res 30(9): 2392-2398, 2016-This study was aimed to determine the effects of a plyometric long jump training program on torque around the lower limb joints and kinetic and kinematics parameters during the swimming jump start. Ten swimmers performed 3 identical assessment sessions, measuring hip and knee muscle extensors during maximal voluntary isometric contraction and kinetic and kinematics parameters during the swimming jump start, at 3 instants: INI (2 weeks before the training program, control period), PRE (2 weeks after INI measurements), and POST (24-48 hours after 9 weeks of training). There were no significant changes from INI to PRE measurements. However, the peak torque and rate of torque development increased significantly from PRE to POST measurements for both hip (47 and 108%) and knee (24 and 41%) joints. There were significant improvements to the horizontal force (7%), impulse (9%), and angle of resultant force (19%). In addition, there were significant improvements to the center of mass displacement (5%), horizontal takeoff velocity (16%), horizontal velocity at water entrance (22%), and peak angle velocity for the knee (15%) and hip joints (16%). Therefore, the plyometric long jump training protocol was effective to enhance torque around the lower limb joints and to control the resultant vector direction, to increase the swimming jump start performance. These findings suggest that coaches should use long jump training instead of vertical jump training to improve swimming start performance.
Advancements in the Development of an Operational Lightning Jump Algorithm for GOES-R GLM
Shultz, Chris; Petersen, Walter; Carey, Lawrence
2011-01-01
Rapid increases in total lightning have been shown to precede the manifestation of severe weather at the surface. These rapid increases have been termed lightning jumps, and are the current focus of algorithm development for the GOES-R Geostationary Lightning Mapper (GLM). Recent lightning jump algorithm work has focused on evaluation of algorithms in three additional regions of the country, as well as, markedly increasing the number of thunderstorms in order to evaluate the each algorithm s performance on a larger population of storms. Lightning characteristics of just over 600 thunderstorms have been studied over the past four years. The 2 lightning jump algorithm continues to show the most promise for an operational lightning jump algorithm, with a probability of detection of 82%, a false alarm rate of 35%, a critical success index of 57%, and a Heidke Skill Score of 0.73 on the entire population of thunderstorms. Average lead time for the 2 algorithm on all severe weather is 21.15 minutes, with a standard deviation of +/- 14.68 minutes. Looking at tornadoes alone, the average lead time is 18.71 minutes, with a standard deviation of +/-14.88 minutes. Moreover, removing the 2 lightning jumps that occur after a jump has been detected, and before severe weather is detected at the ground, the 2 lightning jump algorithm s false alarm rate drops from 35% to 21%. Cold season, low topped, and tropical environments cause problems for the 2 lightning jump algorithm, due to their relative dearth in lightning as compared to a supercellular or summertime airmass thunderstorm environment.
Effect of an Arm Swing on Countermovement Vertical Jump Performance in Elite Volleyball Players
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Vaverka Frantisek
2016-12-01
Full Text Available The aim of this study was to determine how elite volleyball players employed the arm swing (AS to enhance their jump performance. The study assessed how the AS influenced the duration and magnitude of the vertical ground reaction force (VGRF during the main phases (preparatory, braking and accelerating of the countermovement vertical jump (CMVJ, the starting position of the body at the beginning of the accelerating phase and the moment when the AS began contributing to increasing the jump height. Eighteen elite volleyball players performed three CMVJs with and without an AS. Kinetics and kinematics data were collected using two Kistler force plates and the C-motion system. The time and force variables were evaluated based on the VGRF, and the position of the body and the trajectory of the arm movement were determined using kinematic analysis. The AS improved the CMVJ by increasing the jump height by 38% relative to jumping without an AS. The AS significantly shortened the braking phase and prolonged the accelerating phase, however, it did not influence the preparatory phase or the overall jump duration. The AS also significantly increased the average force during the accelerating phase as well as the accelerating impulse. The AS upward began at 76% into the overall jump duration. The AS did not influence the body position at the beginning of the accelerating phase. These findings can be used to improve performance of the CMVJ with the AS and in teaching beginning volleyball players proper jumping technique.
Pricing Participating Products under a Generalized Jump-Diffusion Model
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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.
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Miran Pehar
2017-04-01
Full Text Available The importance of jumping ability in basketball is well known, but there is an evident lack of studies that have examined different jumping testing protocols in basketball players at advanced levels. The aim of this study was to assess the applicability of different tests of jumping capacity in identifying differences between (i playing position and (ii competitive levels of professional players. Participants were 110 male professional basketball players (height: 194.92±8.09 cm; body mass: 89.33±10.91 kg; 21.58±3.92 years of age; Guards, 49; Forwards, 22; Centres, 39 who competed in the first (n = 58 and second division (n = 52. The variables included anthropometrics and jumping test performance. Jumping performances were evaluated by the standing broad jump (SBJ, countermovement jump (CMJ, reactive strength index (RSI, repeated reactive strength ability (RRSA and four running vertical jumps: maximal jump with (i take-off from the dominant leg and (ii non-dominant leg, lay-up shot jump with take-off from the (iii dominant leg and (iv non-dominant leg. First-division players were taller (ES: 0.76, 95%CI: 0.35-1.16, moderate differences, heavier (0.69, 0.29-1.10, had higher maximal reach height (0.67, 0.26-1.07, moderate differences, and had lower body fat % (-0.87, -1.27-0.45, moderate differences than second-division players. The playing positions differed significantly in three of four running jump achievements, RSI and RRSA, with Centres being least successful. The first-division players were superior to second-division players in SBJ (0.63, 0.23-1.03; 0.87, 0.26-1.43; 0.76, 0.11-1.63, all moderate differences, for total sample, Guards, and Forwards, respectively. Running vertical jumps and repeated jumping capacity can be used as valid measures of position-specific jumping ability in basketball. The differences between playing levels in vertical jumping achievement can be observed by assessing vertical jump scores together with differences
Pehar, Miran; Sekulic, Damir; Sisic, Nedim; Spasic, Miodrag; Uljevic, Ognjen; Krolo, Ante; Milanovic, Zoran; Sattler, Tine
2017-09-01
The importance of jumping ability in basketball is well known, but there is an evident lack of studies that have examined different jumping testing protocols in basketball players at advanced levels. The aim of this study was to assess the applicability of different tests of jumping capacity in identifying differences between (i) playing position and (ii) competitive levels of professional players. Participants were 110 male professional basketball players (height: 194.92±8.09 cm; body mass: 89.33±10.91 kg; 21.58±3.92 years of age; Guards, 49; Forwards, 22; Centres, 39) who competed in the first (n = 58) and second division (n = 52). The variables included anthropometrics and jumping test performance. Jumping performances were evaluated by the standing broad jump (SBJ), countermovement jump (CMJ), reactive strength index (RSI), repeated reactive strength ability (RRSA) and four running vertical jumps: maximal jump with (i) take-off from the dominant leg and (ii) non-dominant leg, lay-up shot jump with take-off from the (iii) dominant leg and (iv) non-dominant leg. First-division players were taller (ES: 0.76, 95%CI: 0.35-1.16, moderate differences), heavier (0.69, 0.29-1.10), had higher maximal reach height (0.67, 0.26-1.07, moderate differences), and had lower body fat % (-0.87, -1.27-0.45, moderate differences) than second-division players. The playing positions differed significantly in three of four running jump achievements, RSI and RRSA, with Centres being least successful. The first-division players were superior to second-division players in SBJ (0.63, 0.23-1.03; 0.87, 0.26-1.43; 0.76, 0.11-1.63, all moderate differences, for total sample, Guards, and Forwards, respectively). Running vertical jumps and repeated jumping capacity can be used as valid measures of position-specific jumping ability in basketball. The differences between playing levels in vertical jumping achievement can be observed by assessing vertical jump scores together with differences
EFFECTS OF PLYOMETRIC TRAINING ON THE DEVELOPMENT THE VERTICAL JUMP IN VOLLEYBALL PLAYERS
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Soundara rajan R
2010-08-01
Full Text Available Abstract:The present study investigated the effect of plyometric training on development of the vertical jump of volleyball players. The study consisted of 30 male volleyball players from PSG College of Arts & Science, Coimbatore, their age ranged from 18 to 25 years. Participants articipants were randomly assigned Group I underwent plyometric training group and Group II control group. The plyometric training group carried out a set of plyometric exercises also designed by the researcher twice a week for six weeks. The control group was allowed to play their game, but they were not given any treatments. For the purpose of this research, two tests forthe evaluation of the volleyball vertical jump were validated: the block jump and spike jump. The data was analysed using Paired t-tests which were used to test the effect of treatment groups individually between pre and post –tests, of all the groups, on variables used in the present study. The analysis of covariance was used toanalsze the collected data. The result of the study reveals that there was significant difference in 0.05 levels.Based on the findings of the research and the discussion, one could conclude that the exercise model for the development of the vertical jump that had been used, as the fundamental factor of the experimental group, has contributed to the statistically significant difference in the increase of the vertical jump in comparison to thecontrol group, which had used technically tactical contents to develop the vertical jump.
Ankle brace attenuates the medial-lateral ground reaction force during basketball rebound jump
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Alex Castro
Full Text Available ABSTRACT Introduction: The jump landing is the leading cause for ankle injuries in basketball. It has been shown that the use of ankle brace is effective to prevent these injuries by increasing the mechanical stability of the ankle at the initial contact of the foot with the ground. Objective: To investigate the effects of ankle brace on the ground reaction force (GRF during the simulation of a basketball rebound jump. Method: Eleven young male basketball players randomly carried out a simulated basketball rebound jump under two conditions, with and without ankle brace (lace-up. Dynamic parameters of vertical GRF (take-off and landing vertical peaks, time to take-off and landing vertical peaks, take-off impulse peak, impulse at 50 milliseconds of landing, and jump height and medial-lateral (take-off and landing medial-lateral peaks, and time to reach medial-lateral peaks at take-off and landing were recorded by force platform during rebound jumps in each tested condition. The comparisons between the tested conditions were performed by paired t test (P0.05. Conclusion: The use of ankle brace during basketball rebound jumps attenuates the magnitude of medial-lateral GRF on the landing phase, without changing the vertical GRF. This finding indicates that the use of brace increases the medial-lateral mechanical protection by decreasing the shear force exerted on the athlete’s body without change the application of propulsive forces in the take-off and the impact absorption quality in the landing during the basketball rebound jump.
The influence of measurement and relaxation time on flux jumps in high temperature superconductors
International Nuclear Information System (INIS)
Yang Xiaobin; Zhou Youhe; Tu Shandong
2010-01-01
The influence of the magnetization and relaxation time on flux jumps in high temperature superconductors (HTSC) under varying magnetic field is studied using the fundamental electromagnetic field equations and the thermal diffusion equation; temperature variety corresponding to flux jump is also discussed. We find that for a low sweep rate of the applied magnetic field, the measurement and relaxation times can reduce flux jump and to constrain the number of flux jumps, even stabilizing the HTSC, since much heat produced by the motion of magnetic flux can transfer into coolant during the measurement and relaxation times. As high temperature superconductors are subjected to a high sweep rate or a strong pulsed magnetic field, magnetization undergoes from stability or oscillation to jump for different pause times. And the period of temperature oscillation is equal to the measurement and relaxation time.
Nordic ski jumping injuries. A survey of active American jumpers.
Wright, J R; McIntyre, L; Rand, J J; Hixson, E G
1991-01-01
Little data are available in the medical literature on nordic ski jumping injuries. Injury questionnaires were sent to all active American ski jumpers registered either with the United States Ski Association or with a jumping club registered with the United States Ski Association. One hundred thirty-three of 286 (46.5%) injury questionnaires were returned. Eighty-one of the 133 respondents (60.9%) had been injured sufficiently to require examination by a physician at least once during their jumping careers. This report describes the types and frequencies of injuries sustained by this group of nordic ski jumpers as well as provides demographic data about American ski jumpers. The risk of injury per 100 participant years was 9.4, a rate less than that reported for most high school or college intermural sports.
Intermittency and dynamical Lee-Yang zeros of open quantum systems.
Hickey, James M; Flindt, Christian; Garrahan, Juan P
2014-12-01
We use high-order cumulants to investigate the Lee-Yang zeros of generating functions of dynamical observables in open quantum systems. At long times the generating functions take on a large-deviation form with singularities of the associated cumulant generating functions-or dynamical free energies-signifying phase transitions in the ensemble of dynamical trajectories. We consider a driven three-level system as well as the dissipative Ising model. Both systems exhibit dynamical intermittency in the statistics of quantum jumps. From the short-time behavior of the dynamical Lee-Yang zeros, we identify critical values of the counting field which we attribute to the observed intermittency and dynamical phase coexistence. Furthermore, for the dissipative Ising model we construct a trajectory phase diagram and estimate the value of the transverse field where the stationary state changes from being ferromagnetic (inactive) to paramagnetic (active).
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Tuba KIZILET BOZDOĞAN
2017-12-01
Full Text Available Aim: The aim of this study is to reveal the effect of coordination and plyometric exercises on agility and coordination of jumping ability and other biomotor abilities in badminton. Material and Method: The study groups consisted of badminton athletes with a mean age of 21±1 years. As a pre- and post-tests are agility tests (T-test and Repeated ability test, leg strength tests (countermovement jump test, squat jump test, standing long jump, single leg jump test, Yo-Yo Intermittent Recovery Test Level 1(YYIRTL1 and blood lactate test. Independent sample t-test was used for statistical analysis of the differences between the groups in the measurements, and statistical analysis of the intra-group difference was assessed using the paired sample t-test (p0.05. In the plyometric group, there was a significant difference in countermovement jump, squat jump, standing long jump (p0.05. Conclusion: Reason for the greater changes in the plyometric group can be explained by the coordination and plyometric studies that were planned regularly in this period. The coordination exercises and plyometric exercises for this group at 8 weeks resulted in a meaningful change. Particularly badminton should be placed in excessive amounts before workout training to improve the jump and agility feature which are important parameters.
Generalized thermalization for integrable system under quantum quench.
Muralidharan, Sushruth; Lochan, Kinjalk; Shankaranarayanan, S
2018-01-01
We investigate equilibration and generalized thermalization of the quantum Harmonic chain under local quantum quench. The quench action we consider is connecting two disjoint harmonic chains of different sizes and the system jumps between two integrable settings. We verify the validity of the generalized Gibbs ensemble description for this infinite-dimensional Hilbert space system and also identify equilibration between the subsystems as in classical systems. Using Bogoliubov transformations, we show that the eigenstates of the system prior to the quench evolve toward the Gibbs Generalized Ensemble description. Eigenstates that are more delocalized (in the sense of inverse participation ratio) prior to the quench, tend to equilibrate more rapidly. Further, through the phase space properties of a generalized Gibbs ensemble and the strength of stimulated emission, we identify the necessary criterion on the initial states for such relaxation at late times and also find out the states that would potentially not be described by the generalized Gibbs ensemble description.
Snowboard jumping, Newton’s second law and the force on landing
O'Shea, Michael J.
2004-07-01
An application of Newton’s second law to a snowboarder dropping off a vertical ledge shows that the average normal force during landing (force exerted by the ground on the snowboarder) is determined by four factors. It is shown that the flexing of the legs, the softness of the snow, the angle of the landing surface and the forward motion of the snowboarder can contribute significantly to reducing the force on landing. A judicious choice of the geometry of the jump leads to a force on landing that is equal to the force that the snowboarder would feel if they were standing at the landing point independent of the height from which the snowboarder jumps. Thus we are able to explain with a relatively simple model why a snowboarder may jump from rather high ledges and land comfortably. The physics here is also applicable to jumps in other sports including skiing and mountain biking. The importance of knowing the limits of models is discussed and some of the limits of this model are pointed out.
Magnetization jumps in nanostructured Nd–Fe–B alloy at low temperatures
International Nuclear Information System (INIS)
Neznakhin, D.S.; Bolyachkin, A.S.; Volegov, A.S.; Markin, P.E.; Andreev, S.V.; Kudrevatykh, N.V.
2015-01-01
Magnetic properties of the nanostructured isotropic alloy on the base of Nd 2 Fe 14 B type phase were investigated at low temperatures. The evaluated average grain size of this phase was much smaller than its critical single domain diameter. Hence the magnetization and demagnetization processes were expected to be performed by coherent magnetization rotation. For such coercivity type system magnetization jumps were revealed on the demagnetization hysteresis loop branch in the vicinity of the coercive force at temperatures below 4 K. It was shown that magnetization jumps have a stochastic behavior and their number strongly depends on the temperature and the mass of measured samples. High temperature spikes corresponding to magnetization discontinuities were observed. All these results allowed to propose that magnetization jumps in nanostructured magnetics with magnetization rotation reversal processes comply with the local heating model. - Highlights: • Magnetization reversals of the nanostructured Nd–Fe–B-type alloy were obtained below 4 K. • Magnetization jumps were first observed for magnetization rotation coercivity type magnets. • Staircase magnetization reversal was explained within the framework of the local heating model
A system to measure the kinematics during the entire ski jump sequence using inertial sensors.
Chardonnens, Julien; Favre, Julien; Cuendet, Florian; Gremion, Gérald; Aminian, Kamiar
2013-01-04
Three-dimensional analysis of the entire sequence in ski jumping is recommended when studying the kinematics or evaluating performance. Camera-based systems which allow three-dimensional kinematics measurement are complex to set-up and require extensive post-processing, usually limiting ski jumping analyses to small numbers of jumps. In this study, a simple method using a wearable inertial sensors-based system is described to measure the orientation of the lower-body segments (sacrum, thighs, shanks) and skis during the entire jump sequence. This new method combines the fusion of inertial signals and biomechanical constraints of ski jumping. Its performance was evaluated in terms of validity and sensitivity to different performances based on 22 athletes monitored during daily training. The validity of the method was assessed by comparing the inclination of the ski and the slope at landing point and reported an error of -0.2±4.8°. The validity was also assessed by comparison of characteristic angles obtained with the proposed system and reference values in the literature; the differences were smaller than 6° for 75% of the angles and smaller than 15° for 90% of the angles. The sensitivity to different performances was evaluated by comparing the angles between two groups of athletes with different jump lengths and by assessing the association between angles and jump lengths. The differences of technique observed between athletes and the associations with jumps length agreed with the literature. In conclusion, these results suggest that this system is a promising tool for a generalization of three-dimensional kinematics analysis in ski jumping. Copyright © 2012 Elsevier Ltd. All rights reserved.
Analysis of jumping in the spike, block and set skills of female volleyball players
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Valdir José Barbanti
2007-09-01
Full Text Available The purpose of this study was to quantify the different types of jump observed during volleyball matches. Jumps were classifi ed as block jumps, spike jumps or set jumps. The sample was 12 video-taped National Women’s Volleyball League matches. They were analyzed for specifi c types of jumping, such as spike jumps with and without approach; block jumps with and without step movement; and set jumps. Matches were recorded by two video cameras placed at the back court on each side of the net. Data were collected from the video tapes and each variable was recorded on a sheet of paper for subsequent statistical analysis. The results demonstrated that the highest mean numbers of any jump type per game performed by setters were of the type set jump: 39.0 ± 5.51, 57.3 ± 32.23 and 33 ± 8.49, in games of 3, 4 and 5 sets respectively. For outside hitter players the greatest number of jumps were of the type spike jump with approach, in games of 3, 4 and 5 sets respectively (20.44 ± 5.15, 29.23 ± 7.16 and 35.67 ± 13.21. Middle block players exhibited mean values for block jumps with step movements of 17.04 ± 8.19, 29.9 ± 10.85 and 34.25 ± 5.62, respectively. These results indicate that there was no difference between outside hitters and middle block players in 5-set games in terms of numbers of spike jumps with approach. There was a significant difference between setters and outside hitters in numbers of spike jumps without approach, in games of 3 and 5 sets. There were no differences between any of the positions in block jumps with step in games of 3, 4 or 5 sets. There was no difference between middle block and outside hitter players in terms of set jumps. It was concluded that setters exhibited the highest average number of set jumps per game, outside hitters exhibited the highest mean number of spike jumps with approach and middle block players exhibited highest mean numbers per match of block jumps with step movement. ABSTRACT O presente