Fault-tolerant composite Householder reflection

NASA Astrophysics Data System (ADS)

Torosov, Boyan T.; Kyoseva, Elica; Vitanov, Nikolay V.

2015-07-01

We propose a fault-tolerant implementation of the quantum Householder reflection, which is a key operation in various quantum algorithms, quantum-state engineering, generation of arbitrary unitaries, and entanglement characterization. We construct this operation using the modular approach of composite pulses and a relation between the Householder reflection and the quantum phase gate. The proposed implementation is highly insensitive to variations in the experimental parameters, which makes it suitable for high-fidelity quantum information processing.

A new method to identify the location of the kick point during the golf swing.

PubMed

Joyce, Christopher; Burnett, Angus; Matthews, Miccal

2013-12-01

No method currently exists to determine the location of the kick point during the golf swing. This study consisted of two phases. In the first phase, the static kick point of 10 drivers (having identical grip and head but fitted with shafts of differing mass and stiffness) was determined by two methods: (1) a visual method used by professional club fitters and (2) an algorithm using 3D locations of markers positioned on the golf club. Using level of agreement statistics, we showed the latter technique was a valid method to determine the location of the static kick point. In phase two, the validated method was used to determine the dynamic kick point during the golf swing. Twelve elite male golfers had three shots analyzed for two drivers fitted with stiff shafts of differing mass (56 g and 78 g). Excellent between-trial reliability was found for dynamic kick point location. Differences were found for dynamic kick point location when compared with static kick point location, as well as between-shaft and within-shaft. These findings have implications for future investigations examining the bending behavior of golf clubs, as well as being useful to examine relationships between properties of the shaft and launch parameters.

Well-behaved dynamics in a dissipative nonideal periodically kicked rotator.

PubMed

Chacón, R; Martínez García-Hoz, A

2003-12-01

Well-behaved dynamical properties are found in a dissipative kicked rotator subjected to a periodic string of asymmetric pulses of finite amplitude and width. The stability boundaries of the equilibrium are determined to arbitrary approximation for trigonometric pulses by means of circular harmonic balance, and to first approximation for general elliptic pulses by means of an elliptic harmonic balance method. The bifurcation behavior at the stability boundaries is determined numerically. We show how the extension of the instability region of the equilibrium in pulse parameter space reaches a maximum as the pulse width is varied. We also characterize the dependence of the mean duration of the transients to the equilibrium on the pulse width. The evolution of the basins of attraction of chaotic attractors when solely the pulse width is varied is characterized numerically. Finally, we show that the order-chaos route when solely the width of the pulses is altered appears to be especially rich, including different types of crises. The mechanism underlying these reshaping-induced crises is discussed with the aid of a two-dimensional map.

Complex Instruction Set Quantum Computing

NASA Astrophysics Data System (ADS)

Sanders, G. D.; Kim, K. W.; Holton, W. C.

1998-03-01

In proposed quantum computers, electromagnetic pulses are used to implement logic gates on quantum bits (qubits). Gates are unitary transformations applied to coherent qubit wavefunctions and a universal computer can be created using a minimal set of gates. By applying many elementary gates in sequence, desired quantum computations can be performed. This reduced instruction set approach to quantum computing (RISC QC) is characterized by serial application of a few basic pulse shapes and a long coherence time. However, the unitary matrix of the overall computation is ultimately a unitary matrix of the same size as any of the elementary matrices. This suggests that we might replace a sequence of reduced instructions with a single complex instruction using an optimally taylored pulse. We refer to this approach as complex instruction set quantum computing (CISC QC). One trades the requirement for long coherence times for the ability to design and generate potentially more complex pulses. We consider a model system of coupled qubits interacting through nearest neighbor coupling and show that CISC QC can reduce the time required to perform quantum computations.

Kick Detection at the Bit: Early Detection via Low Cost Monitoring

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

Tost, Brian; Rose, Kelly; Aminzadeh, Fred

2016-06-07

Formation fluid influxes (i.e. kicks) pose persistent challenges and operational costs during drilling operations. Implications of kicks range in scale but cumulatively result in substantial costs that affect drilling safety, environment, schedule, and infrastructure. Early kick detection presents a low-cost, easily adopted solution for avoiding well control challenges associated with kicks near the bit. Borehole geophysical tools used during the drilling process as part of the logging-while-drilling (LWD) and measurement-while-drilling (MWD) provide the advantage of offering real-time downhole data. LWD/MWD collect data on both the annulus and borehole wall. The annular data are normally treated as background, and are filteredmore » out to isolate the formation measurements. Because kicks will change the local physical properties of annular fluids, bottom-hole measurements are among the first indicators that a formation fluid has invaded the wellbore. This report describes and validates a technique for using the annular portion of LWD/MWD data to facilitate early kick detection using first order principles. The detection technique leverages data from standard and cost-effective technologies that are typically implemented during well drilling, such as MWD/LWD data in combination with mud-pulse telemetry for data transmission.« less

Experimental Observation of Dynamical Localization in Laser-Kicked Molecular Rotors

NASA Astrophysics Data System (ADS)

Bitter, M.; Milner, V.

2016-09-01

The periodically kicked rotor is a paradigm system for studying quantum effects on classically chaotic dynamics. The wave function of the quantum rotor localizes in angular momentum space, similarly to Anderson localization of the electronic wave function in disordered solids. Here, we observe dynamical localization in a system of true quantum rotors by subjecting nitrogen molecules to periodic sequences of femtosecond pulses. Exponential distribution of the molecular angular momentum—the hallmark of dynamical localization—is measured directly by means of coherent Raman scattering. We demonstrate the suppressed rotational energy growth with the number of laser kicks and study the dependence of the localization length on the kick strength. Because of its quantum coherent nature, both timing and amplitude noise are shown to destroy the localization and revive the diffusive growth of energy.

Experimental Observation of Dynamical Localization in Laser-Kicked Molecular Rotors.

PubMed

Bitter, M; Milner, V

2016-09-30

The periodically kicked rotor is a paradigm system for studying quantum effects on classically chaotic dynamics. The wave function of the quantum rotor localizes in angular momentum space, similarly to Anderson localization of the electronic wave function in disordered solids. Here, we observe dynamical localization in a system of true quantum rotors by subjecting nitrogen molecules to periodic sequences of femtosecond pulses. Exponential distribution of the molecular angular momentum-the hallmark of dynamical localization-is measured directly by means of coherent Raman scattering. We demonstrate the suppressed rotational energy growth with the number of laser kicks and study the dependence of the localization length on the kick strength. Because of its quantum coherent nature, both timing and amplitude noise are shown to destroy the localization and revive the diffusive growth of energy.

The attenuation of strike acceleration with the use of safety equipment in tae kwon do.

PubMed

Gupta, Sanjey

2011-12-01

THE OBJECTIVES OF THIS STUDY INCLUDE: (1) Determination of the attenuation of strike acceleration that Tae Kwon Do sparring safety pads provide from kicks from Olympic style TKD fighters, (2) The sex and weight differentiation in acceleration achieved within the thorax model with the roundhouse kicks. This prospective, observational study utilized 15 Olympic style fighters from an "elite" team kicking a water core heavy bag thorax model with roundhouse kicks. The model was fitted with a tri-axial accelerometer (GCDC, model X250-2) to measure g acceleration from strikes to the bag. The bag was kicked in three, 10 kick phases by all subjects: kicks without padding; kicks with hogu on heavy bag, and kicks with hogu and instep guards on feet. The g acceleration readings were recorded in all phases. Kolmogorov-Smirnov failed for all variables. There were 8 female subjects: median age 14 years, median weight 53.4 kg and 7 male subjects: median age 17 years, median weight 70.45 kg. The ANOVA on ranks of the acceleration from kicks against the bag achieved significance, P=0.001. Spearman rank order correlation between the weights of players and acceleration of strike against the hogu without and with insteps pads was significant, P=0.035/r=0.54 and P=0.018/r=0.59, respectively. Heavier and male subjects tend to produce more force in strikes. Protective chest guard reduces acceleration to the thorax model, but the utility of instep guards is questionable.

Experimental investigation of early-time diffusion in the quantum kicked rotor using a Bose-Einstein condensate.

PubMed

Duffy, G J; Parkins, S; Müller, T; Sadgrove, M; Leonhardt, R; Wilson, A C

2004-11-01

We report measurements of the early-time momentum diffusion for the atom-optical delta-kicked rotor. In this experiment a Bose-Einstein condensate provides a source of ultracold atoms with an ultranarrow initial momentum distribution, which is then subjected to periodic pulses (or "kicks") using an intense far-detuned optical standing wave. We characterize the effect of varying the effective Planck's constant for the system, while keeping all other parameters fixed. The observed behavior includes both quantum resonances (ballistic energy growth) and antiresonances (re-establishment of the initial state). Our experimental results are compared with theoretical predictions.

Momentum distributions for the quantum delta-kicked rotor with decoherence

PubMed

Vant; Ball; Christensen

2000-05-01

We report on the momentum distribution line shapes for the quantum delta-kicked rotor in the presence of environment induced decoherence. Experimental and numerical results are presented. In the experiment ultracold cesium atoms are subjected to a pulsed standing wave of near resonant light. Spontaneous scattering of photons destroys dynamical localization. For the scattering rates used in our experiment the momentum distribution shapes remain essentially exponential.

Intra-limb coordination in karate kicking: Effect of impacting or not impacting a target.

PubMed

Quinzi, Federico; Sbriccoli, Paola; Alderson, Jacqueline; Di Mario, Alberto; Camomilla, Valentina

2014-02-01

This study aimed to investigate the kicking limb coordinative patterns adopted by karate practitioners (karateka) when impacting (IRK), or not impacting (NIRK) a target during a roundhouse kick. Six karateka performed three repetitions of both kicks while kicking limb kinematics were recorded using a stereophotogrammetric system. Intra-limb coordination was quantified for hip and knee flexion-extension from toe-off to kick completion, using the Continuous relative phase (CRP). Across the same time interval, thigh and shank angular momentum about the vertical axis of the body was calculated. For all trials, across all participants, CRP curve peaks and maximum and minimum angular momentum were determined. A RM-ANOVA was performed to test for differences between kicking conditions. The CRP analysis highlighted, during the central portion of both kicks, a delayed flexion of the hip with respect to the knee. Conversely, during the terminal portion of the CRP curves, the NIRK is performed with a more in-phase action, caused by a higher hip angular displacement. The NIRK is characterized by a lower angular momentum which may enhance control of the striking limb. It would seem that the issue of no impact appears to be solved through the control of all segments of the kicking limb, in contrast to the primary control of the lower leg only observed during the IRK. Copyright © 2013 Elsevier B.V. All rights reserved.

Optimal control of the orientation and alignment of an asymmetric-top molecule with terahertz and laser pulses

NASA Astrophysics Data System (ADS)

Coudert, L. H.

2018-03-01

Quantum optimal control theory is applied to determine numerically the terahertz and nonresonant laser pulses leading, respectively, to the highest degree of orientation and alignment of the asymmetric-top H2S molecule. The optimized terahertz pulses retrieved for temperatures of zero and 50 K lead after 50 ps to an orientation with ⟨ΦZx⟩ = 0.959 73 and ⟨⟨ΦZx⟩⟩ = 0.742 30, respectively. For the zero temperature, the orientation is close to its maximum theoretical value; for the higher temperature, it is below the maximum theoretical value. The mechanism by which the terahertz pulse populates high lying rotational levels is elucidated. The 5 ps long optimized laser pulse calculated for a zero temperature leads to an alignment with ⟨ΦZy 2 ⟩ =0.944 16 and consists of several kick pulses with a duration of ≈0.1 ps. It is found that the timing of these kick pulses is such that it leads to an increase of the rotational energy of the molecule. The optimized laser pulse retrieved for a temperature of 20 K is 6 ps long and yields a lower alignment with ⟨⟨ΦZy 2 ⟩ ⟩ =0.717 20 .

Matrix elements and duality for type 2 unitary representations of the Lie superalgebra gl(m|n)

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

Werry, Jason L.; Gould, Mark D.; Isaac, Phillip S.

The characteristic identity formalism discussed in our recent articles is further utilized to derive matrix elements of type 2 unitary irreducible gl(m|n) modules. In particular, we give matrix element formulae for all gl(m|n) generators, including the non-elementary generators, together with their phases on finite dimensional type 2 unitary irreducible representations which include the contravariant tensor representations and an additional class of essentially typical representations. Remarkably, we find that the type 2 unitary matrix element equations coincide with the type 1 unitary matrix element equations for non-vanishing matrix elements up to a phase.

The Attenuation of Strike Acceleration with the Use of Safety Equipment in Tae Kwon Do

PubMed Central

Gupta, Sanjey

2011-01-01

Purpose The objectives of this study include: (1) Determination of the attenuation of strike acceleration that Tae Kwon Do sparring safety pads provide from kicks from Olympic style TKD fighters, (2) The sex and weight differentiation in acceleration achieved within the thorax model with the roundhouse kicks. Methods This prospective, observational study utilized 15 Olympic style fighters from an “elite” team kicking a water core heavy bag thorax model with roundhouse kicks. The model was fitted with a tri-axial accelerometer (GCDC, model X250-2) to measure g acceleration from strikes to the bag. The bag was kicked in three, 10 kick phases by all subjects: kicks without padding; kicks with hogu on heavy bag, and kicks with hogu and instep guards on feet. The g acceleration readings were recorded in all phases. Results Kolmogorov-Smirnov failed for all variables. There were 8 female subjects: median age 14 years, median weight 53.4 kg and 7 male subjects: median age 17 years, median weight 70.45 kg. The ANOVA on ranks of the acceleration from kicks against the bag achieved significance, P=0.001. Spearman rank order correlation between the weights of players and acceleration of strike against the hogu without and with insteps pads was significant, P=0.035/r=0.54 and P=0.018/r=0.59, respectively. Conclusion Heavier and male subjects tend to produce more force in strikes. Protective chest guard reduces acceleration to the thorax model, but the utility of instep guards is questionable. PMID:22375244

Loading and performance of the support leg in kicking.

PubMed

Ball, Kevin

2013-09-01

The punt kick is important in many football codes and support leg kinematics and ground reaction forces have been implicated in injury and performance in kicking. To evaluate ground reaction forces and support leg kinematics in the punt kick. Cross sectional study. Seven elite Australian football players performed maximal kicks into a net using both the preferred and non-preferred legs. A force plate measured ground reaction forces and an optical motion capture system (200Hz) collected kinematic data during the stance phase of the kick. Preferred and non-preferred legs were compared and performance was evaluated by correlating parameters with foot speed at ball contact. Vertical forces were larger than running at a similar speed but did not reach levels that might be considered an injury risk. Braking forces were directed solely posteriorly, as for soccer kicks, but lateral force patterns varied with some players experiencing greater forces medially and others laterally. A more extended support leg, larger peak vertical and braking force during the stance phase and a shorter stance contact time was associated with larger kick leg foot speed at ball contact. No difference existed between the preferred and non-preferred legs for ground reaction forces or support leg mechanics. To punt kick longer, a straighter support leg, less time on the ground and stronger braking should be encouraged. Conditioning the support leg to provide stronger braking potential is recommended. Copyright © 2012 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Sub-Fourier characteristics of a δ-kicked-rotor resonance.

PubMed

Talukdar, I; Shrestha, R; Summy, G S

2010-07-30

We experimentally investigate the sub-Fourier behavior of a δ-kicked-rotor resonance by performing a measurement of the fidelity or overlap of a Bose-Einstein condensate exposed to a periodically pulsed standing wave. The temporal width of the fidelity resonance peak centered at the Talbot time and zero initial momentum exhibits an inverse cube pulse number (1/N3)-dependent scaling compared to a 1/N2 dependence for the mean energy width at the same resonance. A theoretical analysis shows that for an accelerating potential the width of the resonance in acceleration space depends on 1/N3, a property which we also verify experimentally. Such a sub-Fourier effect could be useful for high precision gravity measurements.

Probing non-unitary CP violation effects in neutrino oscillation experiments

NASA Astrophysics Data System (ADS)

Verma, Surender; Bhardwaj, Shankita

2018-05-01

In the present work, we have considered minimal unitarity violation scheme to obtain the general expression for ν _{μ }→ ν _{τ } oscillation probability in vacuum and matter. For this channel, we have investigated the sensitivities of short baseline experiments to non-unitary parameters |ρ _{μ τ }| and ω _{μ τ } for normal as well as inverted hierarchical neutrino masses and θ _{23} being above or below maximality. We find that for normal hierarchy, the 3σ sensitivity of |ρ _{μ τ }| is maximum for non-unitary phase ω _{μ τ }=0 whereas it is minimum for ω _{μ τ }=± π . For inverted hierarchy, the sensitivity is minimum at ω _{μ τ }=0 and maximum for ω _{μ τ }=± π . We observe that the sensitivity to measure non-unitarity remains unaffected for unitary CP phase δ =0 or δ =π /2 . We have, also, explored wide spectrum of L/E ratio to investigate the possibilities to observe CP-violation due to unitary (δ ) and non-unitary (ω _{μ τ } ) phases. We find that the both phases can be disentangled, in principle, from each other for L/E<200 km/GeV.

Ultrafast harmonic rf kicker design and beam dynamics analysis for an energy recovery linac based electron circulator cooler ring

DOE PAGES

Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.; ...

2016-08-01

An ultrafast kicker system is being developed for the energy recovery linac (ERL) based electron circulator cooler ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously named MEIC). In the CCR, the injected electron bunches can be recirculated while performing ion cooling for 10–30 turns before the extraction, thus reducing the recirculation beam current in the ERL to 1/10–1/30 (150mA–50 mA) of the cooling beam current (up to 1.5 A). Assuming a bunch repetition rate of 476.3 MHz and a recirculating factor of 10 in the CCR, the kicker is required to operate at a pulse repetitionmore » rate of 47.63 MHz with pulse width of around 2 ns, so that only every 10th bunch in the CCR will experience a transverse kick while the rest of the bunches will not be disturbed. Such a kicker pulse can be synthesized by ten harmonic modes of the 47.63 MHz kicker pulse repetition frequency, using up to four quarter wavelength resonator (QWR) based deflecting cavities. In this paper, several methods to synthesize such a kicker waveform will be discussed and a comparison of their beam dynamics performance is made using ELEGANT. Four QWR cavities are envisaged with high transverse shunt impedance requiring less than 100 W of total rf power for a Flat-Top kick pulse. Multipole fields due to the asymmetry of this type of cavity are analyzed. The transverse emittance growth due to the sextupole component is simulated in ELEGANT. In conclusion, off-axis injection and extraction issues and beam optics using a multicavity kick-drift scheme will also be discussed.« less

Ultrafast harmonic rf kicker design and beam dynamics analysis for an energy recovery linac based electron circulator cooler ring

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

Huang, Yulu; Wang, Haipeng; Rimmer, Robert A.

An ultrafast kicker system is being developed for the energy recovery linac (ERL) based electron circulator cooler ring (CCR) in the proposed Jefferson Lab Electron Ion Collider (JLEIC, previously named MEIC). In the CCR, the injected electron bunches can be recirculated while performing ion cooling for 10–30 turns before the extraction, thus reducing the recirculation beam current in the ERL to 1/10–1/30 (150mA–50 mA) of the cooling beam current (up to 1.5 A). Assuming a bunch repetition rate of 476.3 MHz and a recirculating factor of 10 in the CCR, the kicker is required to operate at a pulse repetitionmore » rate of 47.63 MHz with pulse width of around 2 ns, so that only every 10th bunch in the CCR will experience a transverse kick while the rest of the bunches will not be disturbed. Such a kicker pulse can be synthesized by ten harmonic modes of the 47.63 MHz kicker pulse repetition frequency, using up to four quarter wavelength resonator (QWR) based deflecting cavities. In this paper, several methods to synthesize such a kicker waveform will be discussed and a comparison of their beam dynamics performance is made using ELEGANT. Four QWR cavities are envisaged with high transverse shunt impedance requiring less than 100 W of total rf power for a Flat-Top kick pulse. Multipole fields due to the asymmetry of this type of cavity are analyzed. The transverse emittance growth due to the sextupole component is simulated in ELEGANT. In conclusion, off-axis injection and extraction issues and beam optics using a multicavity kick-drift scheme will also be discussed.« less

Characterization of pseudosingle bunch kick-and-cancel operational mode

DOE PAGES

Sun, C.; Robin, D. S.; Steier, C.; ...

2015-12-18

Pseudosingle-bunch kick-and-cancel (PSB-KAC) is a new operational mode at the Advanced Light Source of Lawrence Berkeley National Laboratory that provides full timing and repetition rate control for single x-ray pulse users while being fully transparent to other users of synchrotron radiation light. In this operational mode, a single electron bunch is periodically displaced from a main bunch train by a fast kicker magnet with a user-on-demand repetition rate, creating a single x-ray pulse to be matched to a typical laser excitation pulse rate. This operational mode can significantly improve the signal to noise ratio of single x-ray pulse experiments andmore » drastically reduce dose-induced sample damage rate. It greatly expands the capabilities of synchrotron light sources to carry out dynamics and time-of-flight experiments. In this paper, we carry out extensive characterizations of this PSB-KAC mode both numerically and experimentally. This includes the working principle of this mode, resonance conditions and beam stability, experimental setups, and diagnostic tools and measurements.« less

Segment coupling and coordination variability analyses of the roundhouse kick in taekwondo relative to the initial stance position.

PubMed

Estevan, Isaac; Freedman Silvernail, Julia; Jandacka, Daniel; Falco, Coral

2016-09-01

The initial stance position (ISP) has been observed as a factor affecting the execution technique during taekwondo kicks. In the present study, authors aimed to analyse a roundhouse kick to the chest by measuring movement coordination and the variability of coordination and comparing this across the different ISP (0°, 45° and 90°). Eight experienced taekwondo athletes performed consecutive kicking trials in random order from every of the three relative positions. The execution was divided into three phases (stance, first swing and second swing phase). A motion capture system was used to measure athletes' angular displacement of pelvis and thigh. A modified vector coding technique was used to quantify the coordination of the segments which contributed to the overall movement. The variability of this coordination (CV) for each ISP was also calculated. Comparative analysis showed that during the stance phase in the transverse plane, athletes coordinated movement of the trunk and thigh with a higher frequency of in-phase and lower frequency of exclusive thigh rotation in the 0° stance than the 90° stance position (P < 0.05). CV was also influenced by the different ISP. During the first swing and the majority of the second swing phase, predominant in-phase coordination of the pelvis and thigh was observed. Including exercises that require in-phase movement could not only help athletes to acquire coordination stability but also efficiency. The existence of a constraint such as ISP implies an increase of the variability when the athletes have to kick from ISP they are not used to adopt (i.e., 0° and 90° ISP) as an evidence of adaptability in the athletes' execution technique.

Correlated states of a quantum oscillator acted by short pulses

NASA Technical Reports Server (NTRS)

Manko, O. V.

1993-01-01

Correlated squeezed states for a quantum oscillator are constructed based on the method of quantum integrals of motion. The quantum oscillator is acted upon by short duration pulses. Three delta-kickings of frequency are used to model the pulses' dependence upon the time aspects of the frequency of the oscillator. Additionally, the correlation coefficient and quantum variances of operations of coordinates and momenta are written in explicit form.

Project K.I.C.K., A School-Based Drug Education Research Project--Peers, Parents and Kids.

ERIC Educational Resources Information Center

Rollin, Stephen A.; And Others

1994-01-01

Evaluated first phase of three-phase research project, Project KICK (Kids in Cooperation with Kids) by examining interaction between parent education, positive peer role modeling, and drug education for third graders. Hypothesized that intervention would lead to increase in self-esteem, improved attitudes, increased knowledge regarding drugs, and…

Kicks from the penalty mark in soccer: the roles of stress, skill, and fatigue for kick outcomes.

PubMed

Jordet, Geir; Hartman, Esther; Visscher, Chris; Lemmink, Koen A P M

2007-01-15

The soccer "penalty shootout" in the knock-out phase of major international tournaments is one of the most dramatic events in international soccer. The outcome of these kicks is typically attributed to factors such as psychology (e.g. coping with stress), skill (e.g. kicking technique), physiology (e.g. overcoming the fatigue of 120 min play), and chance (e.g. in what direction the goalkeeper moves). The purpose of this study was to use internet game record data to estimate the relative importance of these performance components for the outcome of penalty kicks in international matches. Data were collected from soccer statistics internet sites on all 41 penalty shootouts and 409 kicks taken in the World Cup, European Championships, and Copa America between 1976 and 2004. The results showed that the importance of the kicks (indicative of stress) was negatively related to the outcomes of the kicks, whereas skill and fatigue were less, or not, related to outcome. It was concluded that psychological components are most influential for the outcome of penalty kicks. We recommend that practitioners work with players to reduce the perceived importance of each kick.

Effectiveness of roundhouse kick in elite Taekwondo athletes.

PubMed

Thibordee, Sutima; Prasartwuth, Orawan

2014-06-01

The roundhouse kick is a powerful attack in Taekwondo. Most athletes intently perform this kick for scoring in competition. Therefore, kinematic and kinetic analyzes of this kick were the topics of interest; however, they were separately investigated and rarely recorded for impact force. Our objectives were to investigate knee and ankle joint kinematics and electromyographic (EMG) activity of leg muscle and compare them between high-impact (HI) and low-impact (LO) kicks. Sixteen male black-belt Taekwondo athletes performed five roundhouse kicks at their maximal effort. Electrogoniometer sensors measured angular motions of ankle and knee joints. Surface EMG activities were recorded for tibialis anterior, gastrocnemius medialis, rectus femoris, and biceps femoris muscles. Based on maximal impact forces, the athletes were classified into HI and LO groups. All athletes in both groups showed greater activation of rectus femoris than other muscles. The HI group only showed significantly less plantarflexion angles than the LO group during preimpact and impact phases (P<0.05). During the impact phase, the HI group demonstrated significantly greater biceps femoris activation than the LO group (P<0.05). In conclusion, rectus femoris activation could predominantly contribute to the powerful roundhouse kicks. Moreover, high biceps femoris co-activation and optimal angle of ankle plantarflexion of about 35° could help achieve the high impact force. Copyright © 2014 Elsevier Ltd. All rights reserved.

A previous hamstring injury affects kicking mechanics in soccer players.

PubMed

Navandar, Archit; Veiga, Santiago; Torres, Gonzalo; Chorro, David; Navarro, Enrique

2018-01-10

Although the kicking skill is influenced by limb dominance and sex, how a previous hamstring injury affects kicking has not been studied in detail. Thus, the objective of this study was to evaluate the effect of sex and limb dominance on kicking in limbs with and without a previous hamstring injury. 45 professional players (males: n=19, previously injured players=4, age=21.16 ± 2.00 years; females: n=19, previously injured players=10, age=22.15 ± 4.50 years) performed 5 kicks each with their preferred and non-preferred limb at a target 7m away, which were recorded with a three-dimensional motion capture system. Kinematic and kinetic variables were extracted for the backswing, leg cocking, leg acceleration and follow through phases. A shorter backswing (20.20 ± 3.49% vs 25.64 ± 4.57%), and differences in knee flexion angle (58 ± 10o vs 72 ± 14o) and hip flexion velocity (8 ± 0rad/s vs 10 ± 2rad/s) were observed in previously injured, non-preferred limb kicks for females. A lower peak hip linear velocity (3.50 ± 0.84m/s vs 4.10 ± 0.45m/s) was observed in previously injured, preferred limb kicks of females. These differences occurred in the backswing and leg-cocking phases where the hamstring muscles were the most active. A variation in the functioning of the hamstring muscles and that of the gluteus maximus and iliopsoas in the case of a previous injury could account for the differences observed in the kicking pattern. Therefore, the effects of a previous hamstring injury must be considered while designing rehabilitation programs to re-educate kicking movement.

Efficient Z gates for quantum computing

NASA Astrophysics Data System (ADS)

McKay, David C.; Wood, Christopher J.; Sheldon, Sarah; Chow, Jerry M.; Gambetta, Jay M.

2017-08-01

For superconducting qubits, microwave pulses drive rotations around the Bloch sphere. The phase of these drives can be used to generate zero-duration arbitrary virtual Z gates, which, combined with two Xπ /2 gates, can generate any SU(2) gate. Here we show how to best utilize these virtual Z gates to both improve algorithms and correct pulse errors. We perform randomized benchmarking using a Clifford set of Hadamard and Z gates and show that the error per Clifford is reduced versus a set consisting of standard finite-duration X and Y gates. Z gates can correct unitary rotation errors for weakly anharmonic qubits as an alternative to pulse-shaping techniques such as derivative removal by adiabatic gate (DRAG). We investigate leakage and show that a combination of DRAG pulse shaping to minimize leakage and Z gates to correct rotation errors realizes a 13.3 ns Xπ /2 gate characterized by low error [1.95 (3 ) ×10-4] and low leakage [3.1 (6 ) ×10-6] . Ultimately leakage is limited by the finite temperature of the qubit, but this limit is two orders of magnitude smaller than pulse errors due to decoherence.

Observation of the Anderson metal-insulator transition with atomic matter waves: Theory and experiment

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

Lemarie, Gabriel; Delande, Dominique; Chabe, Julien

Using a cold atomic gas exposed to laser pulses - a realization of the chaotic quasiperiodic kicked rotor with three incommensurate frequencies - we study experimentally and theoretically the Anderson metal-insulator transition in three dimensions. Sensitive measurements of the atomic wave function and the use of finite-size scaling techniques make it possible to unambiguously demonstrate the existence of a quantum phase transition and to measure its critical exponents. By taking proper account of systematic corrections to one-parameter scaling, we show the universality of the critical exponent {nu}=1.59{+-}0.01, which is found to be equal to the one previously computed for themore » Anderson model.« less

Quantum signature of chaos and thermalization in the kicked Dicke model

NASA Astrophysics Data System (ADS)

Ray, S.; Ghosh, A.; Sinha, S.

2016-09-01

We study the quantum dynamics of the kicked Dicke model (KDM) in terms of the Floquet operator, and we analyze the connection between chaos and thermalization in this context. The Hamiltonian map is constructed by suitably taking the classical limit of the Heisenberg equation of motion to study the corresponding phase-space dynamics, which shows a crossover from regular to chaotic motion by tuning the kicking strength. The fixed-point analysis and calculation of the Lyapunov exponent (LE) provide us with a complete picture of the onset of chaos in phase-space dynamics. We carry out a spectral analysis of the Floquet operator, which includes a calculation of the quasienergy spacing distribution and structural entropy to show the correspondence to the random matrix theory in the chaotic regime. Finally, we analyze the thermodynamics and statistical properties of the bosonic sector as well as the spin sector, and we discuss how such a periodically kicked system relaxes to a thermalized state in accordance with the laws of statistical mechanics.

Quantum signature of chaos and thermalization in the kicked Dicke model.

PubMed

Ray, S; Ghosh, A; Sinha, S

2016-09-01

We study the quantum dynamics of the kicked Dicke model (KDM) in terms of the Floquet operator, and we analyze the connection between chaos and thermalization in this context. The Hamiltonian map is constructed by suitably taking the classical limit of the Heisenberg equation of motion to study the corresponding phase-space dynamics, which shows a crossover from regular to chaotic motion by tuning the kicking strength. The fixed-point analysis and calculation of the Lyapunov exponent (LE) provide us with a complete picture of the onset of chaos in phase-space dynamics. We carry out a spectral analysis of the Floquet operator, which includes a calculation of the quasienergy spacing distribution and structural entropy to show the correspondence to the random matrix theory in the chaotic regime. Finally, we analyze the thermodynamics and statistical properties of the bosonic sector as well as the spin sector, and we discuss how such a periodically kicked system relaxes to a thermalized state in accordance with the laws of statistical mechanics.

Nonexponential Decoherence and Momentum Subdiffusion in a Quantum Lévy Kicked Rotator

NASA Astrophysics Data System (ADS)

Schomerus, Henning; Lutz, Eric

2007-06-01

We investigate decoherence in the quantum kicked rotator (modeling cold atoms in a pulsed optical field) subjected to noise with power-law tail waiting-time distributions of variable exponent (Lévy noise). We demonstrate the existence of a regime of nonexponential decoherence where the notion of a decoherence rate is ill defined. In this regime, dynamical localization is never fully destroyed, indicating that the dynamics of the quantum system never reaches the classical limit. We show that this leads to quantum subdiffusion of the momentum, which should be observable in an experiment.

Different Muscle-Recruitment Strategies Among Elite Breaststrokers.

PubMed

Guignard, Brice; Olstad, Bjørn H; Simbaña Escobar, David; Lauer, Jessy; Kjendlie, Per-Ludvik; Rouard, Annie H

2015-11-01

To investigate electromyographical (EMG) profiles characterizing the lower-limb flexion-extension in an aquatic environment in high-level breaststrokers. The 2-dimensional breaststroke kick of 1 international- and 2 national-level female swimmers was analyzed during 2 maximal 25-m swims. The activities of biceps femoris, rectus femoris, gastrocnemius, and tibialis anterior were recorded. The breaststroke kick was divided in 3 phases, according to the movements performed in the sagittal plane: push phase (PP) covering 27% of the total kick duration, glide phase (GP) 41%, and recovery phase (RP) 32%. Intrasubject reproducibility of the EMG and kinematics was observed from 1 stroke cycle to another. In addition, important intersubject kinematic reproducibility was noted, whereas muscle activities discriminated the subjects: The explosive PP was characterized by important muscle-activation peaks. During the recovery, muscles were likewise solicited for swimmers 1 (S1) and 2 (S2), while the lowest activities were observed during GP for S2 and swimmer 3 (S3), but not for S1, who maintained major muscle solicitations. The main muscle activities were observed during PP to perform powerful lower-limb extension. The most-skilled swimmer (S1) was the only 1 to solicit her muscles during GP to actively reach better streamlining. Important activation peaks during RP correspond to the limbs acting against water drag. Such differences in EMG strategies among an elite group highlight the importance of considering the muscle parameters used to effectively control the intensity of activation among the phases for a more efficient breaststroke kick.

Dynamical decoupling of unbounded Hamiltonians

NASA Astrophysics Data System (ADS)

Arenz, Christian; Burgarth, Daniel; Facchi, Paolo; Hillier, Robin

2018-03-01

We investigate the possibility to suppress interactions between a finite dimensional system and an infinite dimensional environment through a fast sequence of unitary kicks on the finite dimensional system. This method, called dynamical decoupling, is known to work for bounded interactions, but physical environments such as bosonic heat baths are usually modeled with unbounded interactions; hence, here, we initiate a systematic study of dynamical decoupling for unbounded operators. We develop a sufficient decoupling criterion for arbitrary Hamiltonians and a necessary decoupling criterion for semibounded Hamiltonians. We give examples for unbounded Hamiltonians where decoupling works and the limiting evolution as well as the convergence speed can be explicitly computed. We show that decoupling does not always work for unbounded interactions and we provide both physically and mathematically motivated examples.

Efimov-driven phase transitions of the unitary Bose gas.

PubMed

Piatecki, Swann; Krauth, Werner

2014-03-20

Initially predicted in nuclear physics, Efimov trimers are bound configurations of three quantum particles that fall apart when any one of them is removed. They open a window into a rich quantum world that has become the focus of intense experimental and theoretical research, as the region of 'unitary' interactions, where Efimov trimers form, is now accessible in cold-atom experiments. Here we use a path-integral Monte Carlo algorithm backed up by theoretical arguments to show that unitary bosons undergo a first-order phase transition from a normal gas to a superfluid Efimov liquid, bound by the same effects as Efimov trimers. A triple point separates these two phases and another superfluid phase, the conventional Bose-Einstein condensate, whose coexistence line with the Efimov liquid ends in a critical point. We discuss the prospects of observing the proposed phase transitions in cold-atom systems.

Measurement and Comparison of Taekwondo and Yongmudo Turning Kick Impact Force for Two Target Heights

PubMed Central

O’Sullivan, David; Chung, Chulsoo; Lee, Kikwang; Kim, Euihwan; Kang, Sungchul; Kim, Taewhan; Shin, Insik

2009-01-01

The primary purpose of this research was to compare the impact characteristics of Taekwondo (TKD) and Yongmudo (YMD) player’s turning kick according to the target height. 5 highly skilled YMD and 5 TKD players participated in this study. To measure the impact force, two accelerometers were fixed to a PVC pipe in a sandbag. Each participant performed 10 turning kicks trunk and face height in random order. Only the trial with the most accurate (most central impact) measurement was used in the statistical analysis (p < 0.05).There was a significant difference for impact force according to the target height approximately 6400 ± 898 N, 6393 ± 1382 N for the mid section and 5419 ± 659 N, 5475 ± 1293 N for the high section of TKD and YMD groups, but not between groups. The swing phase for the TKD group was significantly shorter than the YMD group’s. The TKD groups’ recovery phase of the trunk height turning kick was significantly shorter. There was a difference in the players’ center of mass (COM) movement as the TKD players’ moved significantly more forward, suggesting that the TKD players tended to slide towards the target during the execution of the kick. In conclusion, as the turning kick was performed quicker by the TKD players with a similar impact force and more forward motion, it is evaluated to be a better technique of turning kicking. Key Points This impact force measuring device had a significantly smaller standard deviation then that of impact force measuring devices. There was a significant difference between the impact forces according to the height approximately 6400 ± 898N, 6393 ± 1382N for the mid section and 5419 ± 659N, 5475 ± 1293N for the high section of TKD and YMD groups. The turning kick was performed quicker by the TKD players with a similar impact force and more forward motion. PMID:24474880

Phase properties of elastic waves in systems constituted of adsorbed diatomic molecules on the (001) surface of a simple cubic crystal

NASA Astrophysics Data System (ADS)

Deymier, P. A.; Runge, K.

2018-03-01

A Green's function-based numerical method is developed to calculate the phase of scattered elastic waves in a harmonic model of diatomic molecules adsorbed on the (001) surface of a simple cubic crystal. The phase properties of scattered waves depend on the configuration of the molecules. The configurations of adsorbed molecules on the crystal surface such as parallel chain-like arrays coupled via kinks are used to demonstrate not only linear but also non-linear dependency of the phase on the number of kinks along the chains. Non-linear behavior arises for scattered waves with frequencies in the vicinity of a diatomic molecule resonance. In the non-linear regime, the variation in phase with the number of kinks is formulated mathematically as unitary matrix operations leading to an analogy between phase-based elastic unitary operations and quantum gates. The advantage of elastic based unitary operations is that they are easily realizable physically and measurable.

Optimized pulses for the control of uncertain qubits

DOE PAGES

Grace, Matthew D.; Dominy, Jason M.; Witzel, Wayne M.; ...

2012-05-18

The construction of high-fidelity control fields that are robust to control, system, and/or surrounding environment uncertainties is a crucial objective for quantum information processing. Using the two-state Landau-Zener model for illustrative simulations of a controlled qubit, we generate optimal controls for π/2 and π pulses and investigate their inherent robustness to uncertainty in the magnitude of the drift Hamiltonian. Next, we construct a quantum-control protocol to improve system-drift robustness by combining environment-decoupling pulse criteria and optimal control theory for unitary operations. By perturbatively expanding the unitary time-evolution operator for an open quantum system, previous analysis of environment-decoupling control pulses hasmore » calculated explicit control-field criteria to suppress environment-induced errors up to (but not including) third order from π/2 and π pulses. We systematically integrate this criteria with optimal control theory, incorporating an estimate of the uncertain parameter to produce improvements in gate fidelity and robustness, demonstrated via a numerical example based on double quantum dot qubits. For the qubit model used in this work, postfacto analysis of the resulting controls suggests that realistic control-field fluctuations and noise may contribute just as significantly to gate errors as system and environment fluctuations.« less

Quantum enhancement of momentum diffusion in the delta-kicked rotor.

PubMed

d'Arcy, M B; Godun, R M; Oberthaler, M K; Cassettari, D; Summy, G S

2001-08-13

We present detailed observations of the quantum delta-kicked rotor in the vicinity of a quantum resonance. Our experiment consists of an ensemble of cold cesium atoms subject to a pulsed off-resonant standing wave of light. We measure the mean energy and show clearly that at the quantum resonance it is a local maximum. We also examine the effect of noise on the system and find that the greatest sensitivity to this occurs at the resonances. This makes these regions ideal for examining quantum-classical correspondence. A picture based on diffraction is developed which allows the experiments to be readily understood.

A new fourth-order Fourier-Bessel split-step method for the extended nonlinear Schroedinger equation

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

Nash, Patrick L.

2008-01-10

Fourier split-step techniques are often used to compute soliton-like numerical solutions of the nonlinear Schroedinger equation. Here, a new fourth-order implementation of the Fourier split-step algorithm is described for problems possessing azimuthal symmetry in 3 + 1-dimensions. This implementation is based, in part, on a finite difference approximation {delta}{sub perpendicular} {sup FDA} of 1/r ({partial_derivative})/({partial_derivative}r) r({partial_derivative})/({partial_derivative}r) that possesses an associated exact unitary representation of e{sup i/2{lambda}}{sup {delta}{sub perpendicular}{sup FDA}}. The matrix elements of this unitary matrix are given by special functions known as the associated Bessel functions. Hence the attribute Fourier-Bessel for the method. The Fourier-Bessel algorithm is shown tomore » be unitary and unconditionally stable. The Fourier-Bessel algorithm is employed to simulate the propagation of a periodic series of short laser pulses through a nonlinear medium. This numerical simulation calculates waveform intensity profiles in a sequence of planes that are transverse to the general propagation direction, and labeled by the cylindrical coordinate z. These profiles exhibit a series of isolated pulses that are offset from the time origin by characteristic times, and provide evidence for a physical effect that may be loosely termed normal mode condensation. Normal mode condensation is consistent with experimentally observed pulse filamentation into a packet of short bursts, which may occur as a result of short, intense irradiation of a medium.« less

Coincidence timing of a soccer pass: effects of stimulus velocity and movement distance.

PubMed

Williams, L R

2000-08-01

The effect of stimulus velocity and movement extent on coincidence timing and spatial accuracy of a soccer pass was investigated. A Bassin anticipation timer provided light stimulus velocities of 1.79 or 2.68 m/sec. (designated as "Low" and "High", respectively), and subjects were required to kick a stationary soccer ball so that it struck a target in coincidence with the arrival of the light stimulus at the end of the runway. Two kick types were used. The "Short" condition began with the subject 70 cm from the ball and required a single forward step with the nonkicking leg before making the kick. The "Long" condition began 140 cm from the ball and required two steps before the kick. Twenty male subjects were given 16 trials under each of the four combinations of stimulus velocity and kick type. The expectation that the faster stimulus velocity would be associated with lower coincidence timing scores for both absolute error (AE) and variable error (VE) and with late responding for constant error (CEO) was upheld with the exception that for the Long Kick-High Velocity condition, AE was highest. The index of preprogramming (IP) was used to test the hypothesis that a two-stage control process would characterise coincidence anticipation performance involving whole-body movements. Results showed that the preparatory phase of responding produced zero-order IPs signifying reliance on feedback control. Also, while the striking phase produced high IP and suggested reliance on preprogrammed control, the possibility that the High Velocity conditions may have limited the responses was recognised. As a consequence, the role of open-loop processes remained equivocal. The findings are, however, in agreement with the view that the sensorimotor and movement-execution phases of responding require a process that is characterised by adaptability to regulatory features of the environment via closed loop mechanisms involving perception-action coupling.

Controlled ultrafast transfer and stability degree of generalized coherent states of a kicked two-level ion

NASA Astrophysics Data System (ADS)

Chen, Hao; Kong, Chao; Hai, Wenhua

2018-06-01

We investigate quantum dynamics of a two-level ion trapped in the Lamb-Dicke regime of a δ -kicked optical lattice, based on the exact generalized coherent states rotated by a π / 2 pulse of Ramsey type experiment. The spatiotemporal evolutions of the spin-motion entangled states in different parameter regions are illustrated, and the parameter regions of different degrees of quantum stability described by the quantum fidelity are found. Time evolutions of the probability for the ion being in different pseudospin states reveal that the ultrafast entanglement generation and population transfers of the system can be analytically controlled by managing the laser pulses. The probability in an initially disentangled state shows periodic collapses (entanglement) and revivals (de-entanglement). Reduction of the stability degree results in enlarging the period of de-entanglement, while the instability and potential chaos will cause the sustained entanglement. The results could be justified experimentally in the existing setups and may be useful in engineering quantum dynamics for quantum information processing.

Effect of Leg Dominance on The Center-of-Mass Kinematics During an Inside-of-the-Foot Kick in Amateur Soccer Players.

PubMed

Zago, Matteo; Motta, Andrea Francesco; Mapelli, Andrea; Annoni, Isabella; Galvani, Christel; Sforza, Chiarella

2014-09-29

Soccer kicking kinematics has received wide interest in literature. However, while the instep-kick has been broadly studied, only few researchers investigated the inside-of-the-foot kick, which is one of the most frequently performed techniques during games. In particular, little knowledge is available about differences in kinematics when kicking with the preferred and non-preferred leg. A motion analysis system recorded the three-dimensional coordinates of reflective markers placed upon the body of nine amateur soccer players (23.0 ± 2.1 years, BMI 22.2 ± 2.6 kg/m2), who performed 30 pass-kicks each, 15 with the preferred and 15 with the non-preferred leg. We investigated skill kinematics while maintaining a perspective on the complete picture of movement, looking for laterality related differences. The main focus was laid on: anatomical angles, contribution of upper limbs in kick biomechanics, kinematics of the body Center of Mass (CoM), which describes the whole body movement and is related to balance and stability. When kicking with the preferred leg, CoM displacement during the ground-support phase was 13% higher (p<0.001), normalized CoM height was 1.3% lower (p<0.001) and CoM velocity 10% higher (p<0.01); foot and shank velocities were about 5% higher (p<0.01); arms were more abducted (p<0.01); shoulders were rotated more towards the target (p<0.01, 6° mean orientation difference). We concluded that differences in motor control between preferred and non-preferred leg kicks exist, particularly in the movement velocity and upper body kinematics. Coaches can use these results to provide effective instructions to players in the learning process, moving their focus on kicking speed and upper body behavior.

Multi-Pulse Extraction from Los Alamos Proton Storage Ring for Radiographic Applications

NASA Astrophysics Data System (ADS)

Thiessen, Henry A.; Neri, Filippo; Rust, Kenneth R.; Redd, Dale B.

1997-05-01

For radiography of moving objects, two or more pulses with adjustable time spacing are required. The existing Proton Stotage Ring (PSR) extraction system is configured to extract the entire beam in a single turn. Two kickers and two kicker modulators fired at the same time perform the normal extraction function. By reconfiguring the two kickers and two modulators, it is possible to obtain two half-sized extraction kicks with adjustable time spacing. In this way, we have extracted two pulses with adjustable relative timing. The setup will be described and experimental results will be presented.

Kicked-Harper model versus on-resonance double-kicked rotor model: From spectral difference to topological equivalence

NASA Astrophysics Data System (ADS)

Wang, Hailong; Ho, Derek Y. H.; Lawton, Wayne; Wang, Jiao; Gong, Jiangbin

2013-11-01

Recent studies have established that, in addition to the well-known kicked-Harper model (KHM), an on-resonance double-kicked rotor (ORDKR) model also has Hofstadter's butterfly Floquet spectrum, with strong resemblance to the standard Hofstadter spectrum that is a paradigm in studies of the integer quantum Hall effect. Earlier it was shown that the quasienergy spectra of these two dynamical models (i) can exactly overlap with each other if an effective Planck constant takes irrational multiples of 2π and (ii) will be different if the same parameter takes rational multiples of 2π. This work makes detailed comparisons between these two models, with an effective Planck constant given by 2πM/N, where M and N are coprime and odd integers. It is found that the ORDKR spectrum (with two periodic kicking sequences having the same kick strength) has one flat band and N-1 nonflat bands with the largest bandwidth decaying in a power law as ˜KN+2, where K is a kick strength parameter. The existence of a flat band is strictly proven and the power-law scaling, numerically checked for a number of cases, is also analytically proven for a three-band case. By contrast, the KHM does not have any flat band and its bandwidths scale linearly with K. This is shown to result in dramatic differences in dynamical behavior, such as transient (but extremely long) dynamical localization in ORDKR, which is absent in the KHM. Finally, we show that despite these differences, there exist simple extensions of the KHM and ORDKR model (upon introducing an additional periodic phase parameter) such that the resulting extended KHM and ORDKR model are actually topologically equivalent, i.e., they yield exactly the same Floquet-band Chern numbers and display topological phase transitions at the same kick strengths. A theoretical derivation of this topological equivalence is provided. These results are also of interest to our current understanding of quantum-classical correspondence considering that the KHM and ORDKR model have exactly the same classical limit after a simple canonical transformation.

Dynamic knee stability and ballistic knee movement after ACL reconstruction: an application on instep soccer kick.

PubMed

Cordeiro, Nuno; Cortes, Nelson; Fernandes, Orlando; Diniz, Ana; Pezarat-Correia, Pedro

2015-04-01

The instep soccer kick is a pre-programmed ballistic movement with a typical agonist-antagonist coordination pattern. The coordination pattern of the kick can provide insight into deficient neuromuscular control. The purpose of this study was to investigate knee kinematics and hamstrings/quadriceps coordination pattern during the knee ballistic extension phase of the instep kick in soccer players after anterior cruciate ligament reconstruction (ACL reconstruction). Seventeen players from the Portuguese Soccer League participated in this study. Eight ACL-reconstructed athletes (experimental group) and 9 healthy individuals (control group) performed three instep kicks. Knee kinematics (flexion and extension angles at football contact and maximum velocity instants) were calculated during the kicks. Rectus femoris (RF), vastus lateralis, vastus medialis, biceps femoralis, and semitendinosus muscle activations were quantified during the knee extension phase. The ACL-reconstructed group had significantly lower knee extension angle (-1.2 ± 1.6, p < 0.021) and increased variability (1.1 ± 1.2, p < 0.012) when compared with the control group. Within the EMG variables, the RF had a significantly greater activity in the ACL-reconstructed group than in the control group (79.9 ± 27.7 % MVC vs. 49.2 ± 20.8 % MVC, respectively, p < 0.034). No other statistically significant differences were found. The findings of this study demonstrate that changes in ACL-reconstructed individuals were observed on knee extension angle and RF muscle activation while performing an instep kick. These findings are in accordance with the knee stability recovery process after ACL reconstruction. No differences were observed in the ballistic control movement pattern between normal and ACL-reconstructed subjects. Performing open kinetic chain exercises using ballistic movements can be beneficial when recovering from ACL reconstruction. The exercises should focus on achieving multi-joint coordination and full knee extension (range of motion). III.

Transition and Damping of Collective Modes in a Trapped Fermi Gas between BCS and Unitary Limits near the Phase Transition

PubMed Central

Dong, Hang; Zhang, Wenyuan; Zhou, Li; Ma, Yongli

2015-01-01

We investigate the transition and damping of low-energy collective modes in a trapped unitary Fermi gas by solving the Boltzmann-Vlasov kinetic equation in a scaled form, which is combined with both the T-matrix fluctuation theory in normal phase and the mean-field theory in order phase. In order to connect the microscopic and kinetic descriptions of many-body Feshbach scattering, we adopt a phenomenological two-fluid physical approach, and derive the coupling constants in the order phase. By solving the Boltzmann-Vlasov steady-state equation in a variational form, we calculate two viscous relaxation rates with the collision probabilities of fermion’s scattering including fermions in the normal fluid and fermion pairs in the superfluid. Additionally, by considering the pairing and depairing of fermions, we get results of the frequency and damping of collective modes versus temperature and s-wave scattering length. Our theoretical results are in a remarkable agreement with the experimental data, particularly for the sharp transition between collisionless and hydrodynamic behaviour and strong damping between BCS and unitary limits near the phase transition. The sharp transition originates from the maximum of viscous relaxation rate caused by fermion-fermion pair collision at the phase transition point when the fermion depair, while the strong damping due to the fast varying of the frequency of collective modes from BCS limit to unitary limit. PMID:26522094

Analysis of angular momentum effect on swimming kick-start performance.

PubMed

Taladriz, Sonia; de la Fuente-Caynzos, Blanca; Arellano, Raúl

2016-06-14

The aim of this study was to analyse the mechanics of rotation and the temporal, angular and kinematics variables during the aerial phase for the kick-start with respect to the grab start. Nine elite swimmers (70.0 ± 7.7 kg; 178 ± 9.4 cm; 24.5 ± 5.3 years; 824 ± 119 FINA points scoring) performed the starts on the OMEGA OSB11 starting block followed by 5 m gliding at maximum velocity. Nineteen comparisons of kinematics variables across start technique were performed with critical alpha adjusted using a Holm's correction to maintain an experiment-wise type I error rate of p <0.05. The differences were statistically evaluated by T-test and Wilcoxon test. Significant advantages for the kick-start were observed in all temporal variables (except in the flight time) and in the vertical take-off velocity. Similarities in the centre of mass angular momentum at take-off (120.89 ± 17.66, 126.61 ± 13.51 s(-1).10(-3), p-value <0.294; kick-start and grab start) caused that KS did not increase the temporal advantages obtained on the block at 5 m distance. Two different rotational movements were found for both techniques. A displacement of the rear leg and front leg on the block and during the flight respectively permits a higher lower limbs position relative to the trunk at hands entry for kick-start. However, larger rotational movement of the trunk characterized grab start. It was concluded that shorter block times and rotational displacements of the lower limbs on the block and flight phase are the key of the best performance for kick-start at 5 m distance. Copyright © 2016 Elsevier Ltd. All rights reserved.

Floquet topological phases with symmetry in all dimensions

NASA Astrophysics Data System (ADS)

Roy, Rahul; Harper, Fenner

2017-05-01

Dynamical systems may host a number of remarkable symmetry-protected phases that are qualitatively different from their static analogs. In this work, we consider the phase space of symmetry-respecting unitary evolutions in detail and identify several distinct classes of evolution that host dynamical order. Using ideas from group cohomology, we construct a set of interacting Floquet drives that generate dynamical symmetry-protected topological order for each nontrivial cohomology class in every dimension, illustrating our construction with explicit two-dimensional examples. We also identify a set of symmetry-protected Floquet drives that lie outside of the group cohomology construction, and a further class of symmetry-respecting topological drives which host chiral edge modes. We use these special drives to define a notion of phase (stable to a class of local perturbations in the bulk) and the concepts of relative and absolute topological order, which can be applied to many different classes of unitary evolutions. These include fully many-body localized unitary evolutions and time crystals.

Kinematics and Kinetics of Taekwon-do Side Kick

PubMed Central

Wąsik, Jacek

2011-01-01

The aim of the paper is to present an analysis of the influence of selected kinematic factors on the side kick technique. This issue is especially important in the traditional version of taekwon-do, in which a single strike may reveal the winner. Six taekwon-do (International Taekwon-do Federation) athletes were asked to participate in this case study. Generally accepted criteria of sports technique biomechanical analysis were adhered to. The athletes executed a side kick three times (in Taekwon-do terminology referred to as yop chagi) in a way which they use the kick in board breaking. The obtained data were used to determine the mean velocity changes in the function of relative extension length of the kicking leg. The maximum knee and foot velocities in the Cartesian coordinate system were determined. The leg lifting time and the duration of kick execution as well as the maximum force which the standing foot exerted on the ground were also determined. On the basis of the obtained values, mean values and standard deviations were calculated. The correlation dependence (r=0.72) shows that greater knee velocity affects the velocity which the foot develops as well as the fact that the total time of kick execution depends on the velocity which the knee (r = −0.59) and the foot (r = − 0.86) develop in the leg lifting phase. The average maximum speed was obtained at the length of the leg equal to 82% of the maximum length of the fully extended leg. This length can be considered the optimum value for achieving the maximum dynamics of the kick. PMID:23486086

Comparison of the Kinematic Patterns of Kick Between Brazilian and Japanese Young Soccer Players

PubMed Central

Pereira Santiago, Paulo Roberto; Palucci Vieira, Luiz Henrique; Barbieri, Fabio Augusto; Moura, Felipe Arruda; Exel Santana, Juliana; de Andrade, Vitor Luiz; de Souza Bedo, Bruno Luiz; Cunha, Sergio Augusto

2016-01-01

Background Kicking performance is the most studied technical action in soccer and lower limbs kinematics is closely related to success in kicking, mainly because they are essential in imparting high velocity to the ball. Previous studies demonstrated that soccer leagues in different countries exhibit different physical demands and technical requirements during the matches. However, evidencewhether nationality has any influence in the kinematics of soccer-related skills has not yet been reported. The nationality of the players is an aspect that might be also relevant to the performance in kicking. Objectives The aim of this study was to compare the lower limbs kinematic patterns during kicking, between Brazilian and Japanese young top soccer players. Patients and Methods Seven Brazilian (GA) and seven Japanese (GB) U-17 players performed 15 side-foot kicks each, with a distance of 20 m away from the goal, aiming a target of 1 × 1 m in upper corner, constrained by a defensive wall (1.8 × 2 m). Four digital video cameras (120 Hz) recorded the performance for further 3D reconstruction of thigh, shank and foot segments of both kicking and support limbs. The selected kicking cycle was characterized by the toe-off of the kicking limb to the end of the kicking foot when it came in contact with the ball. Stereographical projection of each segment was applied to obtain the representative curves of kicking as function of time for each participant in each trial. Cluster analysis was performed to identify the mean GA and GB curves for each segment. Silhouette coefficient (SC) was calculated, in order to determine the degree of separation between the two groups’ curves. Results Comparison between the median confidence intervals of the SC showed no differences between groups as regards lower limb patterns of movements. Task accuracy was determined by the relative frequency that the ball reached the target for all attempts and no differences were found (GA: 10.48 ± 14.33%; GB: 9.52 ± 6.51%; P = 0.88). Conclusions We conclude that lower limb kinematic patterns, in support and ball contact phases, are similar in young Brazilian and Japanese soccer players during free kicks when adopting the side-foot kick style. PMID:27625761

Chaotic quantum ratchets and filters with cold atoms in optical lattices: Properties of Floquet states

NASA Astrophysics Data System (ADS)

Hur, Gwang-Ok

The -kicked rotor is a paradigm of quantum chaos. Its realisation with clouds of cold atoms in pulsed optical lattices demonstrated the well-known quantum chaos phenomenon of 'dynamical localisation'. In those experi ments by several groups world-wide, the £-kicks were applied at equal time intervals. However, recent theoretical and experimental work by the cold atom group at UCL Monteiro et al 2002, Jonckheere et al 2003, Jones et al 2004 showed that novel quantum and classical dynamics arises if the atomic cloud is pulsed with repeating sequences of unequally spaced kicks. In Mon teiro et al 2002 it was found that the energy absorption rates depend on the momentum of the atoms relative to the optical lattice hence a type of chaotic ratchet was proposed. In Jonckheere et al and Jones et al, a possible mechanism for selecting atoms according to their momenta (velocity filter) was investigated. The aim of this thesis was to study the properties of the underlying eigen values and eigenstates. Despite the unequally-spaced kicks, these systems are still time-periodic, so we in fact investigated the Floquet states, which are eigenstates of U(T), the one-period time evolution operator. The Floquet states and corresponding eigenvalues were obtained by diagonalising a ma trix representation of the operator U(T). It was found that the form of the eigenstates enables us to analyse qual itatively the atomic momentum probability distributions, N(p) measured experimentally. In particular, the momentum width of the individual eigen states varies strongly with < p > as expected from the theoretical and ex- perimental results obtained previously. In addition, at specific < p > close to values which in the experiment yield directed motion (ratchet transport), the probability distribution of the individual Floquet states is asymmetric, mirroring the asymmetric N(p) measured in clouds of cesium atoms. In the penultimate chapter, the spectral fluctuations (eigenvalue statis tics) are investigated for one particular system, the double-delta kicked rotor. We computed Nearest Neighbour Spacing (NNS) distributions as well as the number variances (E2 statistics). We find that even in regimes where the corresponding classical dynamics are fully chaotic, the statistics are, unex pectedly, intermediate between fully chaotic (GOE) and fully regular (Pois- son). It is argued that they are analogous to the critical statistics seen in the Anderson metal-insulator transition.

Generic superweak chaos induced by Hall effect

NASA Astrophysics Data System (ADS)

Ben-Harush, Moti; Dana, Itzhack

2016-05-01

We introduce and study the "kicked Hall system" (KHS), i.e., charged particles periodically kicked in the presence of uniform magnetic (B ) and electric (E ) fields that are perpendicular to each other and to the kicking direction. We show that for resonant values of B and E and in the weak-chaos regime of sufficiently small nonintegrability parameter κ (the kicking strength), there exists a generic family of periodic kicking potentials for which the Hall effect from B and E significantly suppresses the weak chaos, replacing it by "superweak" chaos (SWC). This means that the system behaves as if the kicking strength were κ2 rather than κ . For E =0 , SWC is known to be a classical fingerprint of quantum antiresonance, but it occurs under much less generic conditions, in particular only for very special kicking potentials. Manifestations of SWC are a decrease in the instability of periodic orbits and a narrowing of the chaotic layers, relative to the ordinary weak-chaos case. Also, for global SWC, taking place on an infinite "stochastic web" in phase space, the chaotic diffusion on the web is much slower than the weak-chaos one. Thus, the Hall effect can be relatively stabilizing for small κ . In some special cases, the effect is shown to cause ballistic motion for almost all parameter values. The generic global SWC on stochastic webs in the KHS appears to be the two-dimensional closest analog to the Arnol'd web in higher dimensional systems.

Local correction of quadrupole errors at LHC interaction regions using action and phase jump analysis on turn-by-turn beam position data

NASA Astrophysics Data System (ADS)

Cardona, Javier Fernando; García Bonilla, Alba Carolina; Tomás García, Rogelio

2017-11-01

This article shows that the effect of all quadrupole errors present in an interaction region with low β * can be modeled by an equivalent magnetic kick, which can be estimated from action and phase jumps found on beam position data. This equivalent kick is used to find the strengths that certain normal and skew quadrupoles located on the IR must have to make an effective correction in that region. Additionally, averaging techniques to reduce noise on beam position data, which allows precise estimates of equivalent kicks, are presented and mathematically justified. The complete procedure is tested with simulated data obtained from madx and 2015-LHC experimental data. The analyses performed in the experimental data indicate that the strengths of the IR skew quadrupole correctors and normal quadrupole correctors can be estimated within a 10% uncertainty. Finally, the effect of IR corrections in the β* is studied, and a correction scheme that returns this parameter to its designed value is proposed.

Randomly displaced phase distribution design and its advantage in page-data recording of Fourier transform holograms.

PubMed

Emoto, Akira; Fukuda, Takashi

2013-02-20

For Fourier transform holography, an effective random phase distribution with randomly displaced phase segments is proposed for obtaining a smooth finite optical intensity distribution in the Fourier transform plane. Since unitary phase segments are randomly distributed in-plane, the blanks give various spatial frequency components to an image, and thus smooth the spectrum. Moreover, by randomly changing the phase segment size, spike generation from the unitary phase segment size in the spectrum can be reduced significantly. As a result, a smooth spectrum including sidebands can be formed at a relatively narrow extent. The proposed phase distribution sustains the primary functions of a random phase mask for holographic-data recording and reconstruction. Therefore, this distribution is expected to find applications in high-density holographic memory systems, replacing conventional random phase mask patterns.

Butterfly Sprint Swimming Technique, Analysis of Somatic and Spatial-Temporal Coordination Variables

PubMed Central

Stanula, Arkadiusz; Krężałek, Piotr; Ostrowski, Andrzej; Kaca, Marcin; Głąb, Grzegorz

2017-01-01

Abstract The aim of this study was to investigate somatic properties and force production of leg extensor muscles measured in the countermovement jump test (CMJ), as well as to analyse kinematic variables of sprint surface butterfly swimming. Thirty-four male competitive swimmers were recruited with an average age of 19.3 ± 1.83 years. Their average body height (BH) was 183.7 ± 5.93 cm, body fat content 10.8 ± 2.64% and body mass (BM) 78.3 ± 5.0 kg. Length measurements of particular body segments were taken and a counter movement jump (CMJ) as well as an all-out 50 m butterfly speed test were completed. The underwater movements of the swimmers’ bodies were recorded with a digital camera providing side-shots. We registered a significant relationship between body mass (r = 0.46), lean body mass (r = 0.48) and sprint surface butterfly swimming (VSBF). The anaerobic power measured in the CMJ test, total body length (TBL) as well as upper and lower extremity length indices did not influence swimming speed significantly. The temporal entry-kick index (the time ratio between the first kick and arm entry) significantly influenced VSBF (r = -0.45). Similarly, medium power of the coefficient was indicated between a) stroke rate kinematics (SR), b) duration of the first leg kick (LP1), c) air phase duration of arm recovery (Fly-arm), and VSBF (r = 0.40; r = 0.40 and r = 0.41, respectively). The entry-kick temporal index showed that, in the butterfly cycle, an appropriately early executed initial kick when compared to arm entry was associated with a longer arm propulsion phase, which in turn was associated with minimizing resistive gliding phases and enabled relatively longer and less resistive air arm recovery (higher value of the fly-arm index). The higher value of SR kinematic was another important element of the best butterfly results in this study. PMID:29339985

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

White, D.B.

This paper reports on experiments to examine gas migration rates in drilling muds that were performed in a 15-m-long, 200-mm-ID inclinable flow loop where air injection simulates gas entry during a kick. These tests were conducted using a xanthum gum (a common polymer used in drilling fluids) solution to simulate drilling muds as the liquid phase and air as the gas phase. This work represents a significant extension of existing correlations for gas/liquid flows in large pipe diameters with non- Newtonian fluids. Bubbles rise faster in drilling muds than in water despite the increased viscosity. This surprising result is causedmore » by the change in the flow regime, with large slug-type bubbles forming at lower void fractions. The gas velocity is independent of void fraction, thus simplifying flow modeling. Results show that a gas influx will rise faster in a well than previously believed. This has major implications for kick simulation, with gas arriving at the surface earlier than would be expected and the gas outflow rate being higher than would have been predicted. A model of the two-phase gas flow in drilling mud, including the results of this work, has been incorporated into the joint Schlumberger Cambridge Research (SCR)/BP Intl. kick model.« less

Short x-ray pulse generation using deflecting cavities at the Advanced Photon Source.

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

Sajaev, V.; Borland, M.; Chae, Y.-C.

2007-11-11

Storage-ring-based third-generation light sources can provide intense radiation pulses with durations as short as 100 ps. However, there is growing interest within the synchrotron radiation user community in performing experiments with much shorter X-ray pulses. Zholents et al. [Nucl. Instr. and Meth. A 425 (1999) 385] recently proposed using RF orbit deflection to generate sub-ps X-ray pulses. In this scheme, two deflecting cavities are used to deliver a longitudinally dependent vertical kick to the beam. An optical slit can then be used to slice out a short part of the radiation pulse. Implementation of this scheme is planned for onemore » APS beamline in the near future. In this paper, we summarize our feasibility study of this method and the expected X-ray beam parameters. We find that a pulse length of less than two picoseconds can be achieved.« less

Propagation of second sound in a superfluid Fermi gas in the unitary limit

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

Arahata, Emiko; Nikuni, Tetsuro

2009-10-15

We study sound propagation in a uniform superfluid gas of Fermi atoms in the unitary limit. The existence of normal and superfluid components leads to appearance of two sound modes in the collisional regime, referred to as first and second sounds. The second sound is of particular interest as it is a clear signal of a superfluid component. Using Landau's two-fluid hydrodynamic theory, we calculate hydrodynamic sound velocities and these weights in the density response function. The latter is used to calculate the response to a sudden modification of the external potential generating pulse propagation. The amplitude of a pulsemore » which is proportional to the weight in the response function is calculated, the basis of the approach of Nozieres and Schmitt-Rink for the BCS-BEC. We show that, in a superfluid Fermi gas at unitarity, the second-sound pulse is excited with an appreciate amplitude by density perturbations.« less

Nonlinear QR code based optical image encryption using spiral phase transform, equal modulus decomposition and singular value decomposition

NASA Astrophysics Data System (ADS)

Kumar, Ravi; Bhaduri, Basanta; Nishchal, Naveen K.

2018-01-01

In this study, we propose a quick response (QR) code based nonlinear optical image encryption technique using spiral phase transform (SPT), equal modulus decomposition (EMD) and singular value decomposition (SVD). First, the primary image is converted into a QR code and then multiplied with a spiral phase mask (SPM). Next, the product is spiral phase transformed with particular spiral phase function, and further, the EMD is performed on the output of SPT, which results into two complex images, Z 1 and Z 2. Among these, Z 1 is further Fresnel propagated with distance d, and Z 2 is reserved as a decryption key. Afterwards, SVD is performed on Fresnel propagated output to get three decomposed matrices i.e. one diagonal matrix and two unitary matrices. The two unitary matrices are modulated with two different SPMs and then, the inverse SVD is performed using the diagonal matrix and modulated unitary matrices to get the final encrypted image. Numerical simulation results confirm the validity and effectiveness of the proposed technique. The proposed technique is robust against noise attack, specific attack, and brutal force attack. Simulation results are presented in support of the proposed idea.

Detuning related coupler kick variation of a superconducting nine-cell 1.3 GHz cavity

NASA Astrophysics Data System (ADS)

Hellert, Thorsten; Dohlus, Martin

2018-04-01

Superconducting TESLA-type cavities are widely used to accelerate electrons in long bunch trains, such as in high repetition rate free electron lasers. The TESLA cavity is equipped with two higher order mode couplers and a fundamental power coupler (FPC), which break the axial symmetry of the cavity. The passing electrons therefore experience axially asymmetrical coupler kicks, which depend on the transverse beam position at the couplers and the rf phase. The resulting emittance dilution has been studied in detail in the literature. However, the kick induced by the FPC depends explicitly on the ratio of the forward to the backward traveling waves at the coupler, which has received little attention. The intention of this paper is to present the concept of discrete coupler kicks with a novel approach of separating the field disturbances related to the standing wave and a reflection dependent part. Particular attention is directed to the role of the penetration depth of the FPC antenna, which determines the loaded quality factor of the cavity. The developed beam transport model is compared to dedicated experiments at FLASH and European XFEL. Both the observed transverse coupling and detuning related coupler kick variations are in good agreement with the model. Finally, the expected trajectory variations due to coupler kick variations at European XFEL are investigated and results of numerical studies are presented.

Loop Braiding Statistics and Interacting Fermionic Symmetry-Protected Topological Phases in Three Dimensions

NASA Astrophysics Data System (ADS)

Cheng, Meng; Tantivasadakarn, Nathanan; Wang, Chenjie

2018-01-01

We study Abelian braiding statistics of loop excitations in three-dimensional gauge theories with fermionic particles and the closely related problem of classifying 3D fermionic symmetry-protected topological (FSPT) phases with unitary symmetries. It is known that the two problems are related by turning FSPT phases into gauge theories through gauging the global symmetry of the former. We show that there exist certain types of Abelian loop braiding statistics that are allowed only in the presence of fermionic particles, which correspond to 3D "intrinsic" FSPT phases, i.e., those that do not stem from bosonic SPT phases. While such intrinsic FSPT phases are ubiquitous in 2D systems and in 3D systems with antiunitary symmetries, their existence in 3D systems with unitary symmetries was not confirmed previously due to the fact that strong interaction is necessary to realize them. We show that the simplest unitary symmetry to support 3D intrinsic FSPT phases is Z2×Z4. To establish the results, we first derive a complete set of physical constraints on Abelian loop braiding statistics. Solving the constraints, we obtain all possible Abelian loop braiding statistics in 3D gauge theories, including those that correspond to intrinsic FSPT phases. Then, we construct exactly soluble state-sum models to realize the loop braiding statistics. These state-sum models generalize the well-known Crane-Yetter and Dijkgraaf-Witten models.

Observation of high-order quantum resonances in the kicked rotor.

PubMed

Kanem, J F; Maneshi, S; Partlow, M; Spanner, M; Steinberg, A M

2007-02-23

Quantum resonances in the kicked rotor are characterized by a dramatically increased energy absorption rate, in stark contrast to the momentum localization generally observed. These resonances occur when the scaled Planck's constant Planck's [over ]=r/s 4pi, for any integers r and s. However, only the variant Planck's [over ]=r2pi resonances are easily observable. We have observed high-order quantum resonances (s>2) utilizing a sample of low energy, noncondensed atoms and a pulsed optical standing wave. Resonances are observed for variant Planck's [over ]=r/16 4pi for integers r=2-6. Quantum numerical simulations suggest that our observation of high-order resonances indicate a larger coherence length (i.e., coherence between different wells) than expected from an initially thermal atomic sample.

Evidence for a Quantum-to-Classical Transition in a Pair of Coupled Quantum Rotors

NASA Astrophysics Data System (ADS)

Gadway, Bryce; Reeves, Jeremy; Krinner, Ludwig; Schneble, Dominik

2013-05-01

The understanding of how classical dynamics can emerge in closed quantum systems is a problem of fundamental importance. Remarkably, while classical behavior usually arises from coupling to thermal fluctuations or random spectral noise, it may also be an innate property of certain isolated, periodically driven quantum systems. Here, we experimentally realize the simplest such system, consisting of two coupled, kicked quantum rotors, by subjecting a coherent atomic matter wave to two periodically pulsed, incommensurate optical lattices. Momentum transport in this system is found to be radically different from that in a single kicked rotor, with a breakdown of dynamical localization and the emergence of classical diffusion. Our observation, which confirms a long-standing prediction for many-dimensional quantum-chaotic systems, sheds new light on the quantum-classical correspondence.

Landscape review of current HIV 'kick and kill' cure research - some kicking, not enough killing.

PubMed

Thorlund, Kristian; Horwitz, Marc S; Fife, Brian T; Lester, Richard; Cameron, D William

2017-08-29

Current antiretroviral therapy (ART) used to treat human immunodeficiency virus (HIV) patients is life-long because it only suppresses de novo infections. Recent efforts to eliminate HIV have tested the ability of a number of agents to reactivate ('Kick') the well-known latent reservoir. This approach is rooted in the assumption that once these cells are reactivated the host's immune system itself will eliminate ('Kill') the virus. While many agents have been shown to reactivate large quantities of the latent reservoir, the impact on the size of the latent reservoir has been negligible. This suggests that the immune system is not sufficient to eliminate reactivated reservoirs. Thus, there is a need for more emphasis on 'kill' strategies in HIV cure research, and how these might work in combination with current or future kick strategies. We conducted a landscape review of HIV 'cure' clinical trials using 'kick and kill' approaches. We identified and reviewed current available clinical trial results in human participants as well as ongoing and planned clinical trials. We dichotomized trials by whether they did not include or include a 'kill' agent. We extracted potential reasons why the 'kill' is missing from current 'kick and kill' strategies. We subsequently summarized and reviewed current 'kill' strategies have entered the phase of clinical trial testing in human participants and highlighted those with the greatest promise. The identified 'kick' trials only showed promise on surrogate measures activating latent T-cells, but did not show any positive effects on clinical 'cure' measures. Of the 'kill' agents currently being tested in clinical trials, early results have shown small but meaningful proportions of participants remaining off ART for several months with broadly neutralizing antibodies, as well as agents for regulating immune cell responses. A similar result was also recently observed in a trial combining a conventional 'kick' with a vaccine immune booster ('kill'). While an understanding of the efficacy of each individual component is crucial, no single 'kick' or 'kill' agent is likely to be a fully effective cure. Rather, the solution is likely found in a combination of multiple 'kick and kill' interventions.

Action-angle variables for the harmonic oscillator: Ambiguity spin × duplication spin

NASA Astrophysics Data System (ADS)

de Oliveira, César R.; Malta, Coraci P.

1984-07-01

The difficulties of obtaining for the harmonic oscillator a well-defined unitary transformation to action-angle variables were overcome by M. Moshinsky and T. H. Seligman ( Ann. Phys. (N.Y.)114 (1978), 243) through the introduction of a spinlike variable (ambiguity spin) from a classical point of view. The difficulty of defining a unitary phase operator for the harmonic oscillator was overcome by Roger G. Newton ( Ann. Phys. (N.Y.)124 (1980), 324) also through the introduction of a spinlike variable (named duplication spin by us) but within a quantum framework. Here the relation between the ambiguity spin and the duplication spin is investigated by introducing these two types of spins in the canonical transformation to action-angle variables. In this way both well-defined unitary transformation and phase operators were obtained.

Optimizing Drilling Efficiency by PWD (Pressure-While-Drilling) Sensor in wells which were drilled in the Khazar-Caspian Sea of the Azerbaijan Republic

NASA Astrophysics Data System (ADS)

Amirov, Elnur

2017-04-01

Sperry Drilling Services' PWD sensor improve and support drilling efficiency by providing very important, real-time downhole pressure information that allows to make faster and better drilling decisions. The PWD service, provides accurate annular pressure, internal pressure and temperature measurements using any of well-known telemetry systems: positive mud pulse, negative mud pulse and electromagnetic. Pressure data can be transmitted in real time and recorded in downhole memory. In the pumpsoff mode, the minimum, maximum and average pressures observed during the non-circulating period are transmitted via mud pulse telemetry when circulation recommences. These measurements provide the knowledge to avoid lost circulation and detect flow/kicks before they happen. The PWD sensor also reduces the risk of problems related by unexpected fracture or collapse. Sperry's PWD sensor also helps to avoid lost circulation and flow/kick, which can lead to costly delays in drilling. Annular pressure increases often reflect ineffective cuttings removal and poor hole cleaning, both of which can lead to lost circulation. The PWD sensor detects the increase and drilling fluid parameters and operating procedures can be modified to improve hole-cleaning efficiency. On extended reach wells, real-time information helps to maintain wellbore pressures between safe operating limits and to monitor hole cleaning. The PWD sensor also provides early detection of well flows and kicks. A drop in pressure, can indicate gas, oil and water kicks. Because the sensor is making its measurement downhole, the PWD sensor makes it possible to detect such pressure drops earlier than more traditional surface measurements. The PWD sensor has high-accuracy quartz gauges and is able to record data because of its battery-powered operation. It is also extremely useful in specialized drilling environments, such as high-pressure/high-temperature, extended-reach and deepwater wells. When combined with the rig management system, surface and downhole measurements, can be compared for more accurate and extensive analysis. PWD sensor was utilized with encouraging results in many wells up to 3000-6000m subsurface reservoirs (these wells were drilled in the Khazar-Caspian region of the Azerbaijan Republic) and acquired PWD RT/RM data implemented for best drilling practices in other brand new drilled offset wells in order to help us achieve our mission to drill safe, faster, on target, optimize drilling efficiency, maximize well value and reservoir insight.

Electrode/Dielectric Strip For High-Energy-Density Capacitor

NASA Technical Reports Server (NTRS)

Yen, Shiao-Ping S.

1994-01-01

Improved unitary electrode/dielectric strip serves as winding in high-energy-density capacitor in pulsed power supply. Offers combination of qualities essential for high energy density: high permittivity of dielectric layers, thinness, and high resistance to breakdown of dielectric at high electric fields. Capacitors with strip material not impregnated with liquid.

Quantum mechanics on phase space: The hydrogen atom and its Wigner functions

NASA Astrophysics Data System (ADS)

Campos, P.; Martins, M. G. R.; Fernandes, M. C. B.; Vianna, J. D. M.

2018-03-01

Symplectic quantum mechanics (SQM) considers a non-commutative algebra of functions on a phase space Γ and an associated Hilbert space HΓ, to construct a unitary representation for the Galilei group. From this unitary representation the Schrödinger equation is rewritten in phase space variables and the Wigner function can be derived without the use of the Liouville-von Neumann equation. In this article the Coulomb potential in three dimensions (3D) is resolved completely by using the phase space Schrödinger equation. The Kustaanheimo-Stiefel(KS) transformation is applied and the Coulomb and harmonic oscillator potentials are connected. In this context we determine the energy levels, the amplitude of probability in phase space and correspondent Wigner quasi-distribution functions of the 3D-hydrogen atom described by Schrödinger equation in phase space.

Cognitive Load in Percentage Change Problems: Unitary, Pictorial, and Equation Approaches to Instruction

ERIC Educational Resources Information Center

Ngu, Bing Hiong; Yeung, Alexander Seeshing; Tobias, Stephen

2014-01-01

Eighth grade students in Australia (N = 60) participated in an experiment on learning how to solve percentage change problems in a regular classroom in three conditions: unitary, pictorial, and equation approaches. The procedure involved a pre-test, an acquisition phase, and a post-test. The main goal was to test the relative merits of the three…

Continuous-variable phase estimation with unitary and random linear disturbance

NASA Astrophysics Data System (ADS)

Delgado de Souza, Douglas; Genoni, Marco G.; Kim, M. S.

2014-10-01

We address the problem of continuous-variable quantum phase estimation in the presence of linear disturbance at the Hamiltonian level by means of Gaussian probe states. In particular we discuss both unitary and random disturbance by considering the parameter which characterizes the unwanted linear term present in the Hamiltonian as fixed (unitary disturbance) or random with a given probability distribution (random disturbance). We derive the optimal input Gaussian states at fixed energy, maximizing the quantum Fisher information over the squeezing angle and the squeezing energy fraction, and we discuss the scaling of the quantum Fisher information in terms of the output number of photons, nout. We observe that, in the case of unitary disturbance, the optimal state is a squeezed vacuum state and the quadratic scaling is conserved. As regards the random disturbance, we observe that the optimal squeezing fraction may not be equal to one and, for any nonzero value of the noise parameter, the quantum Fisher information scales linearly with the average number of photons. Finally, we discuss the performance of homodyne measurement by comparing the achievable precision with the ultimate limit imposed by the quantum Cramér-Rao bound.

Impulse-induced localized control of chaos in starlike networks.

PubMed

Chacón, Ricardo; Palmero, Faustino; Cuevas-Maraver, Jesús

2016-06-01

Locally decreasing the impulse transmitted by periodic pulses is shown to be a reliable method of taming chaos in starlike networks of dissipative nonlinear oscillators, leading to both synchronous periodic states and equilibria (oscillation death). Specifically, the paradigmatic model of damped kicked rotators is studied in which it is assumed that when the rotators are driven synchronously, i.e., all driving pulses transmit the same impulse, the networks display chaotic dynamics. It is found that the taming effect of decreasing the impulse transmitted by the pulses acting on particular nodes strongly depends on their number and degree of connectivity. A theoretical analysis is given explaining the basic physical mechanism as well as the main features of the chaos-control scenario.

HealthKick: a nutrition and physical activity intervention for primary schools in low-income settings

PubMed Central

2010-01-01

Background The burden of non-communicable diseases, including type 2 diabetes, is growing in South Africa. This country has a complex mix of over- and under-nutrition, especially in low-income communities, and concerning levels of physical inactivity in children and youth. This paper describes HealthKick, a school-based nutrition and physical activity intervention in primary schools in these settings aimed at reducing diabetes risk factors. Methods/Design This study includes schools within historically disadvantaged, low-income communities from an urban area close to the city of Cape Town and from two rural areas outside of Cape Town, South Africa. The three Educational Districts involved are Metropole North, Cape Winelands and the Overberg. The study has three phases: intervention mapping and formative assessment, intervention development, and outcome and process evaluation. Sixteen schools were purposively selected to participate in the study and randomly allocated as intervention (eight schools) and control (eight schools). The primary aims of HealthKick are to promote healthful eating habits and increase regular participation in health-enhancing physical activity in children, parents and teachers, to prevent overweight, and reduce risk of chronic diseases (particularly type 2 diabetes); as well as to promote the development of an environment within the school and community that facilitates the adoption of healthy lifestyles. The components of HealthKick are: action planning, toolkit (resource guide, a resource box and physical activity resource bin), and an Educators' Manual, which includes a curriculum component. Discussion This study continues to highlight the key role that educators play in implementing a school-based intervention, but that developing capacity within school staff and stakeholders is not a simple or easy task. In spite of the challenges experienced thus far, valuable findings are being produced from this study, especially from Phase 1. Materials developed could be disseminated to other schools in low-income settings both within and outside of South Africa. Owing to the novelty of the HealthKick intervention in low-income South African primary schools, the findings of the evaluation phase have the potential to impact on policy and practice within these settings. PMID:20604914

Flight Investigation on a Fighter-type Airplane of Factors which Affect the Loads and Load Distributions on the Vertical Tail Surfaces During Rudder Kicks and Fishtails

NASA Technical Reports Server (NTRS)

Boshar, John

1947-01-01

Results are presented of a flight investigation conducted on a fighter-type airplane to determine the factors which affect the loads and load distributions on the vertical tail surfaces in maneuvers. An analysis is made of the data obtained in steady flight, rudder kicks, and fishtail maneuvers. For the rudder kicks, the significant loads were the "deflection load" resulting from an abrupt control deflection and the "dynamic load" consisting of a load corresponding to the new static equilibrium condition for the rudder deflected plus a load due to a transient overshoot. The minimum time to reach the maximum control deflection attainable by the pilot in any flight condition was found to be a constant. In the fishtail maneuvers, it was found that the pilot tends to deflect the rudder in phase with the natural frequency of the airplane. The maximum loads measured in fishtails were of the same order of magnitude as those from a rudder kick in which the rudder is returned to zero at the time of maximum sideslip.

Paired-pulse facilitation and depression at unitary synapses in rat hippocampus: quantal fluctuation affects subsequent release.

PubMed Central

Debanne, D; Guérineau, N C; Gähwiler, B H; Thompson, S M

1996-01-01

1. Excitatory synaptic transmission between pairs of monosynaptically coupled pyramidal cells was examined in rat hippocampal slice cultures. Action potentials were elicited in single CA3 pyramidal cells impaled with microelectrodes and unitary excitatory postsynaptic currents (EPSCs) were recorded in whole-cell voltage-clamped CA1 or CA3 cells. 2. The amplitude of successive unitary EPSCs in response to single action potentials varied. The amplitude of EPSCs was altered by adenosine or changes in the [Mg2+]/[CA2+] ratio. We conclude that single action potentials triggered the release of multiple quanta of glutamate. 3. When two action potentials were elicited in the presynaptic cell, the amplitude of the second EPSC was inversely related to the amplitude of the first. Paired-pulse facilitation (PPF) was observed when the first EPSC was small, i.e. the second EPSC was larger than the first, whereas paired-pulse depression (PPD) was observed when the first EPSC was large. 4. The number of trials displaying PPD was greater when release probability was increased, and smaller when release probability was decreased. 5. PPD was not postsynaptically mediated because it was unaffected by decreasing ionic flux with 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) or receptor desensitization with aniracetam. 6. PPF was maximal at an interstimulus interval of 70 ms and recovered within 500 ms. Recovery from PPD occurred within 5 s. 7. We propose that multiple release sites are formed by the axon of a CA3 pyramidal cell and a single postsynaptic CA1 or CA3 cell. PPF is observed if the first action potential fails to release transmitter at most release sites. PPD is observed if the first action potential successfully triggers release at most release sites. 8. Our observations of PPF are consistent with the residual calcium hypothesis. We conclude that PPD results from a decrease in quantal content, perhaps due to short-term depletion of readily releasable vesicles. PMID:9011608

RF kicker cavity to increase control in common transport lines

DOEpatents

Douglas, David R.; Ament, Lucas J. P.

2017-04-18

A method of controlling e-beam transport where electron bunches with different characteristics travel through the same beam pipe. An RF kicker cavity is added at the beginning of the common transport pipe or at various locations along the common transport path to achieve independent control of different bunch types. RF energy is applied by the kicker cavity kicks some portion of the electron bunches, separating the bunches in phase space to allow independent control via optics, or separating bunches into different beam pipes. The RF kicker cavity is operated at a specific frequency to enable kicking of different types of bunches in different directions. The phase of the cavity is set such that the selected type of bunch passes through the cavity when the RF field is at a node, leaving that type of bunch unaffected. Beam optics may be added downstream of the kicker cavity to cause a further separation in phase space.

Nonlinear Phase Distortion in a Ti:Sapphire Optical Amplifier for Optical Stochastic Cooling

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

Andorf, Matthew; Lebedev, Valeri; Piot, Philippe

2016-06-01

Optical Stochastic Cooling (OSC) has been considered for future high-luminosity colliders as it offers much faster cooling time in comparison to the micro-wave stochastic cooling. The OSC technique relies on collecting and amplifying a broadband optical signal from a pickup undulator and feeding the amplified signal back to the beam. It creates a corrective kick in a kicker undulator. Owing to its superb gain qualities and broadband amplification features, Titanium:Sapphire medium has been considered as a gain medium for the optical amplifier (OA) needed in the OSC*. A limiting factor for any OA used in OSC is the possibility ofmore » nonlinear phase distortions. In this paper we experimentally measure phase distortions by inserting a single-pass OA into one leg of a Mach-Zehnder interferometer. The measurement results are used to estimate the reduction of the corrective kick a particle would receive due to these phase distortions in the kicker undulator.« less

Multiqubit Clifford groups are unitary 3-designs

NASA Astrophysics Data System (ADS)

Zhu, Huangjun

2017-12-01

Unitary t -designs are a ubiquitous tool in many research areas, including randomized benchmarking, quantum process tomography, and scrambling. Despite the intensive efforts of many researchers, little is known about unitary t -designs with t ≥3 in the literature. We show that the multiqubit Clifford group in any even prime-power dimension is not only a unitary 2-design, but also a 3-design. Moreover, it is a minimal 3-design except for dimension 4. As an immediate consequence, any orbit of pure states of the multiqubit Clifford group forms a complex projective 3-design; in particular, the set of stabilizer states forms a 3-design. In addition, our study is helpful in studying higher moments of the Clifford group, which are useful in many research areas ranging from quantum information science to signal processing. Furthermore, we reveal a surprising connection between unitary 3-designs and the physics of discrete phase spaces and thereby offer a simple explanation of why no discrete Wigner function is covariant with respect to the multiqubit Clifford group, which is of intrinsic interest in studying quantum computation.

Tensegrity and motor-driven effective interactions in a model cytoskeleton

NASA Astrophysics Data System (ADS)

Wang, Shenshen; Wolynes, Peter G.

2012-04-01

Actomyosin networks are major structural components of the cell. They provide mechanical integrity and allow dynamic remodeling of eukaryotic cells, self-organizing into the diverse patterns essential for development. We provide a theoretical framework to investigate the intricate interplay between local force generation, network connectivity, and collective action of molecular motors. This framework is capable of accommodating both regular and heterogeneous pattern formation, arrested coarsening and macroscopic contraction in a unified manner. We model the actomyosin system as a motorized cat's cradle consisting of a crosslinked network of nonlinear elastic filaments subjected to spatially anti-correlated motor kicks acting on motorized (fibril) crosslinks. The phase diagram suggests there can be arrested phase separation which provides a natural explanation for the aggregation and coalescence of actomyosin condensates. Simulation studies confirm the theoretical picture that a nonequilibrium many-body system driven by correlated motor kicks can behave as if it were at an effective equilibrium, but with modified interactions that account for the correlation of the motor driven motions of the actively bonded nodes. Regular aster patterns are observed both in Brownian dynamics simulations at effective equilibrium and in the complete stochastic simulations. The results show that large-scale contraction requires correlated kicking.

Unitary-matrix models as exactly solvable string theories

NASA Technical Reports Server (NTRS)

Periwal, Vipul; Shevitz, Danny

1990-01-01

Exact differential equations are presently found for the scaling functions of models of unitary matrices which are solved in a double-scaling limit, using orthogonal polynomials on a circle. For the case of the simplest, k = 1 model, the Painleve II equation with constant 0 is obtained; possible nonperturbative phase transitions exist for these models. Equations are presented for k = 2 and 3, and discussed with a view to asymptotic behavior.

Vibrational Schroedinger Cats

NASA Technical Reports Server (NTRS)

Kis, Z.; Janszky, J.; Vinogradov, An. V.; Kobayashi, T.

1996-01-01

The optical Schroedinger cat states are simple realizations of quantum states having nonclassical features. It is shown that vibrational analogues of such states can be realized in an experiment of double pulse excitation of vibrionic transitions. To track the evolution of the vibrational wave packet we derive a non-unitary time evolution operator so that calculations are made in a quasi Heisenberg picture.

Strong Unitary and Overlap Uncertainty Relations: Theory and Experiment

NASA Astrophysics Data System (ADS)

Bong, Kok-Wei; Tischler, Nora; Patel, Raj B.; Wollmann, Sabine; Pryde, Geoff J.; Hall, Michael J. W.

2018-06-01

We derive and experimentally investigate a strong uncertainty relation valid for any n unitary operators, which implies the standard uncertainty relation and others as special cases, and which can be written in terms of geometric phases. It is saturated by every pure state of any n -dimensional quantum system, generates a tight overlap uncertainty relation for the transition probabilities of any n +1 pure states, and gives an upper bound for the out-of-time-order correlation function. We test these uncertainty relations experimentally for photonic polarization qubits, including the minimum uncertainty states of the overlap uncertainty relation, via interferometric measurements of generalized geometric phases.

Inter-Joint Coordination in Producing Kicking Velocity of Taekwondo Kicks

PubMed Central

Kim, Young Kwan; Kim, Yoon Hyuk; Im, Shin Ja

2011-01-01

The purpose of this study was to investigate joint kinematics of the kicking leg in Taekwondo and to examine the role of inter-joint coordination of the leg in producing the kicking velocity. A new inter-joint coordination index that encompasses three- dimensional hip and knee motions, was defined and applied to the joint kinematic results. Twelve elite Taekwondo athletes participated in this study and performed the back kick, thrashing kick, turning-back kick and roundhouse kick. Our results indicate that the back kick utilized a combination of hip and knee extension to produce the kicking velocity, and was characterized by a pushlike movement. The thrashing kick and turning-back kick utilized a greater degree of hip abduction than the roundhouse kick and back kick, and included complicated knee motions. The new index successfully categorized the thrashing kick and turning-back kick into a push-throw continuum, indicating a change from negative index (opposite direction) to positive index (same direction) of hip and knee motions at the end of the movement. This strategy of push-throw continuum increases the kicking velocity at the moment of impact by applying a throwlike movement pattern. Key points A variety of Taekwondo kicks have unique inter-joint coordination of the kicking leg. The back kick used a combination of hip and knee extension to produce the kicking velocity, and was characterized by a pushlike movement. The new index explained well the inter-joint coordination of three DOF joint motions of two joints in producing kicking velocity (positive values for throwlike movements and negative values for pushlike movements). The index successfully categorized the thrashing kick and turning-back kick into a push-throw continuum. PMID:24149292

Inter-joint coordination in producing kicking velocity of taekwondo kicks.

PubMed

Kim, Young Kwan; Kim, Yoon Hyuk; Im, Shin Ja

2011-01-01

The purpose of this study was to investigate joint kinematics of the kicking leg in Taekwondo and to examine the role of inter-joint coordination of the leg in producing the kicking velocity. A new inter-joint coordination index that encompasses three- dimensional hip and knee motions, was defined and applied to the joint kinematic results. Twelve elite Taekwondo athletes participated in this study and performed the back kick, thrashing kick, turning-back kick and roundhouse kick. Our results indicate that the back kick utilized a combination of hip and knee extension to produce the kicking velocity, and was characterized by a pushlike movement. The thrashing kick and turning-back kick utilized a greater degree of hip abduction than the roundhouse kick and back kick, and included complicated knee motions. The new index successfully categorized the thrashing kick and turning-back kick into a push-throw continuum, indicating a change from negative index (opposite direction) to positive index (same direction) of hip and knee motions at the end of the movement. This strategy of push-throw continuum increases the kicking velocity at the moment of impact by applying a throwlike movement pattern. Key pointsA variety of Taekwondo kicks have unique inter-joint coordination of the kicking leg.The back kick used a combination of hip and knee extension to produce the kicking velocity, and was characterized by a pushlike movement.The new index explained well the inter-joint coordination of three DOF joint motions of two joints in producing kicking velocity (positive values for throwlike movements and negative values for pushlike movements).The index successfully categorized the thrashing kick and turning-back kick into a push-throw continuum.

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[ Louisiana ] February 2018 (6) 02/22: Florida Trustee Implementation Group Releases Phase V.2 Final [ Trustee Council ] 11/07: Florida Trustee Implementation Group Seeks Public Comment on Second Phase of the Group to Hold Annual Public Meeting [ Mississippi ] 10/23: Norriego Point Project Kicks Off [ Florida

Neutron Star Kicks by the Gravitational Tug-boat Mechanism in Asymmetric Supernova Explosions: Progenitor and Explosion Dependence

NASA Astrophysics Data System (ADS)

Janka, Hans-Thomas

2017-03-01

Asymmetric mass ejection in the early phase of supernova (SN) explosions can impart a kick velocity to the new-born neutron star (NS). For neutrino-driven explosions the NS acceleration has been shown to be mainly caused by the gravitational attraction of the anisotropically expelled inner ejecta, while hydrodynamic forces contribute on a subdominant level, and asymmetric neutrino emission plays only a secondary role. Two- and three-dimensional hydrodynamic simulations have demonstrated that this gravitational tug-boat mechanism can explain the observed space velocities of young NSs up to more than 1000 km s-1. Here, we discuss how the NS kick depends on the energy, ejecta mass, and asymmetry of the SN explosion, and what role the compactness of the pre-collapse stellar core plays for the momentum transfer to the NS. We also provide simple analytic expressions for the NS velocity in terms of these quantities. Referring to results of hydrodynamic simulations in the literature, we argue why, within the discussed scenario of NS acceleration, electron-capture SNe, low-mass Fe-core SNe, and ultra-stripped SNe can be expected to have considerably lower intrinsic NS kicks than core-collapse SNe of massive stellar cores. Our basic arguments also remain valid if progenitor stars possess large-scale asymmetries in their convective silicon and oxygen burning layers. Possible scenarios for spin-kick alignment are sketched. Much of our discussion stays on a conceptual and qualitative level, and more work is necessary on the numerical modeling side to determine the dependences of involved parameters, whose prescriptions will be needed for recipes that can be used to better describe NS kicks in binary evolution and population synthesis studies.

Neutron Star Kicks by the Gravitational Tug-boat Mechanism in Asymmetric Supernova Explosions: Progenitor and Explosion Dependence

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

Janka, Hans-Thomas

Asymmetric mass ejection in the early phase of supernova (SN) explosions can impart a kick velocity to the new-born neutron star (NS). For neutrino-driven explosions the NS acceleration has been shown to be mainly caused by the gravitational attraction of the anisotropically expelled inner ejecta, while hydrodynamic forces contribute on a subdominant level, and asymmetric neutrino emission plays only a secondary role. Two- and three-dimensional hydrodynamic simulations have demonstrated that this gravitational tug-boat mechanism can explain the observed space velocities of young NSs up to more than 1000 km s{sup −1}. Here, we discuss how the NS kick depends onmore » the energy, ejecta mass, and asymmetry of the SN explosion, and what role the compactness of the pre-collapse stellar core plays for the momentum transfer to the NS. We also provide simple analytic expressions for the NS velocity in terms of these quantities. Referring to results of hydrodynamic simulations in the literature, we argue why, within the discussed scenario of NS acceleration, electron-capture SNe, low-mass Fe-core SNe, and ultra-stripped SNe can be expected to have considerably lower intrinsic NS kicks than core-collapse SNe of massive stellar cores. Our basic arguments also remain valid if progenitor stars possess large-scale asymmetries in their convective silicon and oxygen burning layers. Possible scenarios for spin-kick alignment are sketched. Much of our discussion stays on a conceptual and qualitative level, and more work is necessary on the numerical modeling side to determine the dependences of involved parameters, whose prescriptions will be needed for recipes that can be used to better describe NS kicks in binary evolution and population synthesis studies.« less

Design of a One-Dimensional Sextupole Using Semi-Analytic Methods

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

Gupta, L.; Nagaitsev, S.; Baturin, S. S.

Sextupole magnets provide position-dependent momentum kicks and are tuned to provide the correct kicks to parti- cles within a small acceptance region in phase space. Sextupoles are useful and even necessary in circular accelerators for chromaticity corrections. They are routinely used in most rings, i.e. CESR. Although sextupole magnets are necessary for particle energy corrections, they also have undesirable effects on dynamic aperture, especially because of their non- linear coupling term in the momentum kick. Studies of integrable systems suggest that there is an analytic way to create transport lattices with specific transfer matrices that limit the momentum kick tomore » one dimension. A one-dimension sex- tupole is needed for chromaticity corrections: a horizontal sextupole for horizontal bending magnets. We know how to make a “composite” horizontal sextupole using regular 2D sextupoles and linear transfer matrices in an ideal thin-lens approximation. Thus, one could create an accelerator lattice using linear elements, in series with sextupole magnets to create a “1D sextupole”. This paper describes progress to- wards realizing a realistic focusing lattice resulting in a 1D sextupole.« less

Biomechanical characteristics and speed adaptation during kick double poling on roller skis in elite cross-country skiers.

PubMed

Göpfert, Caroline; Holmberg, Hans-Christer; Stöggl, Thomas; Müller, Erich; Lindinger, Stefan Josef

2013-06-01

Recent developments in cross-country ski racing should promote the use of kick double poling. This technique, however, has not been the focus in athletes' training and has barely been investigated. The aims of the present study were to develop a function-based phase definition and to analyse speed adaptation mechanisms for kick double poling in elite cross-country skiers. Joint kinematics and pole/plantar forces were recorded in 10 athletes while performing kick double poling at three submaximal roller skiing speeds. A speed increase was associated with increases in cycle length and rate, while absolute poling and leg push-off durations shortened. Despite maintained impulses of force, the peak and average pole/leg forces increased. During double poling and leg push-off, ranges of motion of elbow flexion and extension increased (p < 0.05) and were maintained for hip/knee flexion and extension. Cycle length increase was correlated to increases in average poling force (r = 0.71) and arm swing time (r = 0.88; both p < 0.05). The main speed adaptation was achieved by changes in double poling technique; however, leg push-off showed high variability among elite skiers, thus illustrating important aspects for technique training.

Static vs. Dynamic Acute Stretching Effect on Quadriceps Muscle Activity during Soccer Instep Kicking

PubMed Central

Amiri-Khorasani, Mohammadtaghi; Kellis, Eleftherios

2013-01-01

The purpose of this study was to compare the effects of static and dynamic stretching on quadriceps muscle activation during maximal soccer instep kicking. The kicking motion of twelve male college soccer players (body height: 174.66 ± 5.01 cm; body mass: 72.83 ± 4.83 kg; age: 18.83 ± 0.75 years) was captured using six synchronized high-speed infra-red cameras whilst electromyography (EMG) signals from vastus medialis (VM), lateralis (VL) and rectus femoris (RF) were recorded before and after static or dynamic stretching. Analysis of variance designs showed a higher increase in knee extension angular velocity (9.65% vs. −1.45%, p < 0.001), RF (37.5% vs. −8.33%, p < 0.001), VM (12% vs. −12%, p < 0.018), and VL EMG activity (20% vs. −6.67%, p < 0.001) after dynamic stretching exercises. Based on these results, it could be suggested that dynamic stretching is probably more effective in increasing quadriceps muscle activity and knee extension angular velocity during the final swing phase of a maximal soccer instep kick than static stretching. PMID:24511339

Changes in organisation of instep kicking as a function of wearing compression and textured materials.

PubMed

Hasan, Hosni; Davids, Keith; Chow, Jia Yi; Kerr, Graham

2017-04-01

This study investigated effects of wearing compression garments and textured insoles on modes of movement organisation emerging during performance of lower limb interceptive actions in association football. Participants were six skilled (age = 15.67 ± 0.74 years) and six less-skilled (age = 15.17 ± 1.1 years) football players. All participants performed 20 instep kicks with maximum velocity in four randomly organised insoles and socks conditions, (a) Smooth Socks with Smooth Insoles (SSSI); (b) Smooth Socks with Textured Insoles (SSTI); (c) Compression Socks with Smooth Insoles (CSSI); and (d), Compression Socks with Textured Insoles (CSTI). Results showed that, when wearing textured and compression materials (CSSI condition), less-skilled participants displayed significantly greater hip extension and flexion towards the ball contact phase, indicating larger ranges of motion in the kicking limb than in other conditions. Less-skilled participants also demonstrated greater variability in knee-ankle intralimb (angle-angle plots) coordination modes in the CSTI condition. Findings suggested that use of textured and compression materials increased attunement to somatosensory information from lower limb movement, to regulate performance of dynamic interceptive actions like kicking, especially in less-skilled individuals.

Changes in kinematics and arm-leg coordination during a 100-m breaststroke swim.

PubMed

Oxford, Samuel W; James, Rob S; Price, Michael J; Payton, Carl J; Duncan, Michael J

2017-08-01

The purpose of this study was to compare arm-leg coordination and kinematics during 100 m breaststroke in 26 (8 female; 18 male) specialist breaststroke swimmers. Laps were recorded using three 50-Hz underwater cameras. Heart rate and blood lactate were measured pre- and post-swim. Arm-leg coordination was defined using coordination phases describing continuity between recovery and propulsive phases of upper and lower limbs: coordination phase 1 (time between end of leg kick and start of the arm pull phases); and coordination phase 2 (time between end of arm pull and start of leg kick phases). Duration of stroke phases, coordination phases, swim velocity, stroke length (SL), stroke rate (SR) and stroke index (SI) were analysed during the last three strokes of each lap that were unaffected by turning or finishing. Significant changes in velocity, SI and SL (P < 0.05) were found between laps. Both sexes showed significant increase (P < 0.05) in heart rate and blood lactate pre- to post-swim. Males had significantly (P < 0.01) faster swim velocities resulting from longer SLs (P = 0.016) with no difference in SR (P = 0.064). Sex differences in kinematic parameters can be explained by anthropometric differences providing males with increased propelling efficiency.

The influence of joint rigidity on impact efficiency and ball velocity in football kicking.

PubMed

Peacock, James C A; Ball, Kevin

2018-04-11

Executing any skill with efficiency is important for performance. In football kicking, conflicting and non-significant results have existed between reducing ankle plantarflexion during foot-ball contact with impact efficiency, making it unclear as to its importance as a coaching instruction. The aims of this study were to first validate a mechanical kicking machine with a non-rigid ankle, and secondly compare a rigid to a non-rigid ankle during the impact phase of football kicking. Measures of foot-ball contact for ten trials per ankle configuration were calculated from data recorded at 4000 Hz and compared. The non-rigid ankle was characterised by initial dorsiflexion followed by plantarflexion for the remainder of impact, and based on similarities to punt and instep kicking, was considered valid. Impact efficiency (foot-to-ball speed ratio) was greater for the rigid ankle (rigid = 1.16 ± 0.02; non-rigid = 1.10 ± 0.01; p < 0.001). The rigid ankle was characterised by significantly greater effective mass and significantly less energy losses. Increasing rigidity allowed a greater portion of mass from the shank to be used during the collision. As the ankle remained in plantarflexion at impact end, stored elastic energy was not converted to ball velocity and was considered lost. Increasing rigidity is beneficial for increasing impact efficiency, and therefore ball velocity. Copyright © 2018 Elsevier Ltd. All rights reserved.

Calculation of the transverse kicks generated by the bends of a hollow electron lens

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

Stancari, Giulio

2014-03-25

Electron lenses are pulsed, magnetically confined electron beams whose current-density profile is shaped to obtain the desired effect on the circulating beam in high-energy accelerators. They were used in the Fermilab Tevatron collider for abort-gap clearing, beam-beam compensation, and halo scraping. A beam-beam compensation scheme based upon electron lenses is currently being implemented in the Relativistic Heavy Ion Collider at Brookhaven National Laboratory. This work is in support of a conceptual design of hollow electron beam scraper for the Large Hadron Collider. It also applies to the implementation of nonlinear integrable optics with electron lenses in the Integrable Optics Testmore » Accelerator at Fermilab. We consider the axial asymmetries of the electron beam caused by the bends that are used to inject electrons into the interaction region and to extract them. A distribution of electron macroparticles is deposited on a discrete grid enclosed in a conducting pipe. The electrostatic potential and electric fields are calculated using numerical Poisson solvers. The kicks experienced by the circulating beam are estimated by integrating the electric fields over straight trajectories. These kicks are also provided in the form of interpolated analytical symplectic maps for numerical tracking simulations, which are needed to estimate the effects of the electron lens imperfections on proton lifetimes, emittance growth, and dynamic aperture. We outline a general procedure to calculate the magnitude of the transverse proton kicks, which can then be generalized, if needed, to include further refinements such as the space-charge evolution of the electron beam, magnetic fields generated by the electron current, and longitudinal proton dynamics.« less

Berry phase and entanglement of three qubits in a new Yang-Baxter system

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

Hu Taotao; Xue Kang; Wu Chunfeng

2009-08-15

In this paper we construct a new 8x8M matrix from the 4x4M matrix, where M/M is the image of the braid group representation. The 8x8M matrix and the 4x4M matrix both satisfy extraspecial 2-group algebra relations. By Yang-Baxteration approach, we derive a unitary R({theta},{phi}) matrix from the M matrix with parameters {phi} and {theta}. Three-qubit entangled states can be generated by using the R({theta},{phi}) matrix. A Hamiltonian for three qubits is constructed from the unitary R({theta},{phi}) matrix. We then study the entanglement and Berry phase of the Yang-Baxter system.

Regarding the unitary theory of agonist and antagonist action at presynaptic adrenoceptors.

PubMed

Kalsner, S; Abdali, S A

2001-06-01

1. The linkage between potentiation of field stimulation-induced noradrenaline release and blockade of the presynaptic inhibitory effect of exogenous noradrenaline by a presynaptic antagonist was examined in superfused rabbit aorta preparations. 2. Rauwolscine clearly potentiated the release of noradrenaline in response to 100 pulses at 2 Hz but reduced the capacity of noradrenaline to inhibit transmitter release to a questionable extent, and then only when comparisons were made with untreated, rather then to rauwolscine-treated, controls. 3. Aortic preparations exposed for 60 min to rauwolscine followed by superfusion with antagonist-free Krebs for 60 min retained the potentiation of stimulation-induced transmitter release but no antagonism of the noradrenaline-induced inhibition could be detected at either of two noradrenaline concentrations when comparisons were made with rauwolscine treated controls. 4. Comparisons of the inhibitory effect of exogenous noradrenaline (1.8 x 10-6 M) on transmitter efflux in the presence and absence of rauwolscine pretreatment revealed that the antagonist enhanced rather than antagonized the presynaptic inhibition by noradrenaline. 5 It is concluded that the unitary hypothesis that asserts that antagonist enhancement of transmitter release and its blockade of noradrenaline induced inhibition are manifestations of a unitary event are not supportable.

Comparison of Temporal Parameters of Swimming Rescue Elements When Performed Using Dolphin and Flutter Kick with Fins - Didactical Approach

PubMed Central

Rejman, Marek; Wiesner, Wojciech; Silakiewicz, Piotr; Klarowicz, Andrzej; Abraldes, J. Arturo

2012-01-01

The aim of this study was an analysis of the time required to swim to a victim and tow them back to shore, while perfoming the flutter-kick and the dolphin-kick using fins. It has been hypothesized that using fins while using the dolphin-kick when swimming leads to reduced rescue time. Sixteen lifeguards took part in the study. The main tasks performed by them, were to approach and tow (double armpit) a dummy a distance of 50m while applying either the flutter-kick, or the dolphin-kick with fins. The analysis of the temporal parameters of both techniques of kicking demonstrates that, during the approach to the victim, neither the dolphin (tmean = 32.9s) or the flutter kick (tmean = 33.0s) were significantly faster than the other. However, when used for towing a victim the flutter kick (tmean = 47.1s) was significantly faster when compared to the dolphin-kick (tmean = 52.8s). An assessment of the level of technical skills in competitive swimming, and in approaching and towing the victim, were also conducted. Towing time was significantly correlated with the parameter that linked the temporal and technical dimensions of towing and swimming (difference between flutter kick towing time and dolphin-kick towing time, 100m medley time and the four swimming strokes evaluation). No similar interdependency has been discovered in flutter kick towing time. These findings suggest that the dolphin-kick is a more difficult skill to perform when towing the victim than the flutter-kick. Since the hypothesis stated was not confirmed, postulates were formulated on how to improve dolphin-kick technique with fins, in order to reduce swimming rescue time. Key points The source of reduction of swimming rescue time was researched. Time required to approach and to tow the victim while doing the flutter kick and the dolphin-kick with fins was analyzed. The propulsion generated by dolphin-kick did not make the approach and tow faster than the flutter kick. More difficult skill to realize of dolphin-kick than the flutter-kick was postulated. The criteria for how improve dolphin kick technique with fins were formulated. PMID:24150079

Act on Numbers: Numerical Magnitude Influences Selection and Kinematics of Finger Movement

PubMed Central

Rugani, Rosa; Betti, Sonia; Ceccarini, Francesco; Sartori, Luisa

2017-01-01

In the past decade hand kinematics has been reliably adopted for investigating cognitive processes and disentangling debated topics. One of the most controversial issues in numerical cognition literature regards the origin – cultural vs. genetically driven – of the mental number line (MNL), oriented from left (small numbers) to right (large numbers). To date, the majority of studies have investigated this effect by means of response times, whereas studies considering more culturally unbiased measures such as kinematic parameters are rare. Here, we present a new paradigm that combines a “free response” task with the kinematic analysis of movement. Participants were seated in front of two little soccer goals placed on a table, one on the left and one on the right side. They were presented with left- or right-directed arrows and they were instructed to kick a small ball with their right index toward the goal indicated by the arrow. In a few test trials participants were presented also with a small (2) or a large (8) number, and they were allowed to choose the kicking direction. Participants performed more left responses with the small number and more right responses with the large number. The whole kicking movement was segmented in two temporal phases in order to make a hand kinematics’ fine-grained analysis. The Kick Preparation and Kick Finalization phases were selected on the basis of peak trajectory deviation from the virtual midline between the two goals. Results show an effect of both small and large numbers on action execution timing. Participants were faster to finalize the action when responding to small numbers toward the left and to large number toward the right. Here, we provide the first experimental demonstration which highlights how numerical processing affects action execution in a new and not-overlearned context. The employment of this innovative and unbiased paradigm will permit to disentangle the role of nature and culture in shaping the direction of MNL and the role of finger in the acquisition of numerical skills. Last but not least, similar paradigms will allow to determine how cognition can influence action execution. PMID:28912743

Prebifurcation periodic ghost orbits in semiclassical quantization

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

Kus, M.; Haake, F.; Delande, D.

1993-10-04

Classical periodic orbits are stationary-phase points in path integral representations of quantum propagators. We show that complex solutions of the stationary-phase equation, not corresponding to real classical periodic orbits, give additional contributions to the propagator which can be important, especially near bifurcations. We reveal the existence and relevance of such periodic ghost orbits for a kicked top.

PRELIMINARY TEST RESULTS OF A PROTOTYPE FAST KICKER FOR APS MBA UPGRADE

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

Yao, C.-Y.; Morrison, L.; Sun, X.

The APS multi-bend achromatic (MBA) upgrade storage ring plans to support two bunch fill patterns: a 48-bunch and a 324-bunch. A “swap out” injection scheme is required. In order to provide the required kick to injected beam, to minimize the beam loss and residual oscillation of injected beam, and to minimize the perturbation to stored beam during injection, the rise, fall, and flat-top parts of the kicker pulse must be within a 16.9-ns interval. Stripline-type kickers are chosen for both injection and extraction. We developed a prototype kicker that supports a ±15kV differential pulse voltage. We performed high voltage discharge,more » TDR measurement, high voltage pulse test and beam test of the kicker. We report the final design of the fast kicker and the test results.« less

Construct validity of tests that measure kick performance for young soccer players based on cluster analysis: exploring the relationship between coaches rating and actual measures.

PubMed

Palucci Vieira, Luiz H; de Andrade, Vitor L; Aquino, Rodrigo L; Moraes, Renato; Barbieri, Fabio A; Cunha, Sérgio A; Bedo, Bruno L; Santiago, Paulo R

2017-12-01

The main aim of this study was to verify the relationship between the classification of coaches and actual performance in field tests that measure the kicking performance in young soccer players, using the K-means clustering technique. Twenty-three U-14 players performed 8 tests to measure their kicking performance. Four experienced coaches provided a rating for each player as follows: 1: poor; 2: below average; 3: average; 4: very good; 5: excellent as related to three parameters (i.e. accuracy, power and ability to put spin on the ball). The scores interval established from k-means cluster metric was useful to originating five groups of performance level, since ANOVA revealed significant differences between clusters generated (P<0.01). Accuracy seems to be moderately predicted by the penalty kick, free kick, kicking the ball rolling and Wall Volley Test (0.44≤r≤0.56), while the ability to put spin on the ball can be measured by the free kick and the corner kick tests (0.52≤r≤0.61). Body measurements, age and PHV did not systematically influence the performance. The Wall Volley Test seems to be a good predictor of other tests. Five tests showed reasonable construct validity and can be used to predict the accuracy (penalty kick, free kick, kicking a rolling ball and Wall Volley Test) and ability to put spin on the ball (free kick and corner kick tests) when kicking in soccer. In contrast, the goal kick, kicking the ball when airborne and the vertical kick tests exhibited low power of discrimination and using them should be viewed with caution.

Hot hands, cold feet? Investigating effects of interacting constraints on place kicking performance at the 2015 Rugby Union World Cup.

PubMed

Pocock, Chris; Bezodis, Neil E; Davids, Keith; North, Jamie S

2018-06-23

Place kicks in Rugby Union present valuable opportunities to score points outside the spatiotemporal dynamics of open play but are executed under varying performance constraints. We analysed effects of specific task constraints and relevant contextual factors on place kick performance in the 2015 Rugby Union World Cup. Data were collected from television broadcasts for each place kick. In addition to kick outcomes, contextual factors, including time of the kick in the match, score margin at the time of the kick, and outcome of the kicker's previous kick, were recorded. Effects of spatial task constraints were analysed for each kick, using distance (m) and angle (°) of the kick to the goalposts. A binomial logistic regression model revealed that distance from, and angle to, the goalposts were significant predictors of place kick outcome. Furthermore, the success percentage of kickers who missed their previous kick was 7% lower than those who scored their previous kick. Place kick success percentage in the 10 minutes before half-time was 8% lower than the mean tournament success percentage, which was 75% (95% CI 71-78%). The highest kick success percentage was recorded when scores were level (83%; 95% CI 72-91%). Our data highlighted how subtle changes in task constraints and contextual factors can influence performance outcomes in elite performers in international competition. Fluctuations in place kick success suggested that individual constraints, such as thoughts, emotions and fatigue, induced during competition, could interact with perceptions to influence emergent performance behaviours.

Probing CP violation with non-unitary mixing in long-baseline neutrino oscillation experiments: DUNE as a case study

DOE PAGES

Escrihuela, F. J.; Forero, D. V.; Miranda, O. G.; ...

2017-09-08

When neutrino masses arise from the exchange of neutral heavy leptons, as in most seesaw schemes, the effective lepton mixing matrix N describing neutrino propagation is non-unitary, hence neutrinos are not exactly orthonormal. New CP violation phases appear in N that could be confused with the standard phasemore » $${\\delta }_{\\mathrm{CP}}$$ characterizing the three neutrino paradigm.We study the potential of the long-baseline neutrino experiment DUNE in probing CP violation induced by the standard CP phase in the presence of non-unitarity. In order to accomplish this we develop our previous formalism, so as to take into account the neutrino interactions with the medium, important in long baseline experiments such as DUNE. In this study we find that the expected CP sensitivity of DUNE is somewhat degraded with respect to that characterizing the standard unitary case. However the effect is weaker than might have been expected thanks mainly to the wide neutrino beam. We also investigate the sensitivity of DUNE to the parameters characterizing non-unitarity. In this case we find that there is no improvement expected with respect to the current situation, unless the near detector setup is revamped.« less

Probing CP violation with non-unitary mixing in long-baseline neutrino oscillation experiments: DUNE as a case study

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

Escrihuela, F. J.; Forero, D. V.; Miranda, O. G.

When neutrino masses arise from the exchange of neutral heavy leptons, as in most seesaw schemes, the effective lepton mixing matrix N describing neutrino propagation is non-unitary, hence neutrinos are not exactly orthonormal. New CP violation phases appear in N that could be confused with the standard phasemore » $${\\delta }_{\\mathrm{CP}}$$ characterizing the three neutrino paradigm.We study the potential of the long-baseline neutrino experiment DUNE in probing CP violation induced by the standard CP phase in the presence of non-unitarity. In order to accomplish this we develop our previous formalism, so as to take into account the neutrino interactions with the medium, important in long baseline experiments such as DUNE. In this study we find that the expected CP sensitivity of DUNE is somewhat degraded with respect to that characterizing the standard unitary case. However the effect is weaker than might have been expected thanks mainly to the wide neutrino beam. We also investigate the sensitivity of DUNE to the parameters characterizing non-unitarity. In this case we find that there is no improvement expected with respect to the current situation, unless the near detector setup is revamped.« less

Development, Manufacturing, and Preparation for Serial Production of Low Noise Seismometers Final Report CRADA No. TC02096.0

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

Vergino, E. S.; Passmore, P. R.

2012-01-23

This was a collaborative effort between Lawrence Livermore National Security, LLC as manager and operator of Lawrence Livermore National Laboratory (LLNL) and Refraction Technology, Inc. (REF TEK), to collaborate on the development of a broadband, competitive low-noise seismometer, rugged and easy to use for field deployments. The work involved collaborative work between LLNL, REF TEK and a group led by Federal State Unitary Enterprise, Research Institute of Pulse Technique (RIPT), Moscow, Russia. The proposed work focused on bringing an improved version of the Russian SDSE seismometer from development phase to production in two versions. The first was a very lowmore » cost, rugged, broadband seismometer for field deployment that would achieve noise levels comparable to the standard earth low noise model (LNM) of the USGS. All three components were integrated into one case, and have sensitivity near 2000 v/m/s, and analog output with bandwidth of .01 to 40 Hz with high coherence.« less

Target effect on the kinematics of Taekwondo Roundhouse Kick - is the presence of a physical target a stimulus, influencing muscle-power generation?

PubMed

Wąsik, Jacek; Shan, Gongbing

2015-01-01

Taekwondo is famous for its powerful kicking techniques and the roundhouse kick is the most frequently used one. In earlier literature, the influence of a physical target (exiting or not) on kicking power generation has not been given much attention. Therefore, the aim of this study was to investigate the kinematics of roundhouse kick execution and its factors related to power generation. 6 ITF taekwondo practitioners voluntarily participated in this study. They were asked to perform kicks with and without a physical target. The first kick aimed at breaking a board while the second one was a kick into the air. A Smart-D motion capture system (BTS S.p.A., Italy) was used to quantitatively determine their kinematic characteristics during each kick. The main findings showed that kicks aiming at a breaking board were significantly slower than kicks without a physical target (maximal kick-foot velocities were 10.61 ± 0.86 m/s and 14.61 ± 0.67 m/s, respectively, p < 0.01), but the kicking time of the former was shorter (0.58 ± 0.01 s and 0.67 ± 0.01, respectively, p < 0.01). The results suggest that a physical target will negatively influence the kick-foot velocity, which is not necessarily a disadvantage for creating a high quality kick. Possible motor control mechanisms are discussed for the phenomenon. The study made it clear: trainings with and without physical targets would develop different motor control patterns. More studies are needed for identifying the effectiveness of different controls and efficiencies of their training.

Hamiltonian models for topological phases of matter in three spatial dimensions

NASA Astrophysics Data System (ADS)

Williamson, Dominic J.; Wang, Zhenghan

2017-02-01

We present commuting projector Hamiltonian realizations of a large class of (3 + 1)D topological models based on mathematical objects called unitary G-crossed braided fusion categories. This construction comes with a wealth of examples from the literature of symmetry-enriched topological phases. The spacetime counterparts to our Hamiltonians are unitary state sum topological quantum fields theories (TQFTs) that appear to capture all known constructions in the literature, including the Crane-Yetter-Walker-Wang and 2-Group gauge theory models. We also present Hamiltonian realizations of a state sum TQFT recently constructed by Kashaev whose relation to existing models was previously unknown. We argue that this TQFT is captured as a special case of the Crane-Yetter-Walker-Wang model, with a premodular input category in some instances.

Using telepresence enabled remote-operated vehicles to assess hydrothermal outflow along a collapse scar near the Kick'em Jenny Volcano

NASA Astrophysics Data System (ADS)

Whitley, S. Z.; Mittelstaedt, E. L.

2016-02-01

During expedition NA054 of the E/V Nautilus from 18 September to 9 October 2014 and as part of the TREET (Transforming Remotely Conducted Research through Ethnography, Education, and Rapidly Evolving Technologies) project, a series of photographic surveys along the shoulder of the Kick'em Jenny volcano were performed under direction of a remote research team located at the University of Rhode Island Inner Space Center. The primary goal of these surveys was to map the distribution and extent of active and extinct hydrothermal activity along a large collapse scar surrounding the current edifice of the Kick'em Jenny volcano. Photomosaic surveys cover a area of 3000 m2 and reveal extensive basalt alteration with areas of active diffuse hydrothermal outflow. The spatial extents of orange-colored alteration and white, bacterial mats, taken to indicate active outflow, are quantified using both manual identification and an automated, supervised classification scheme. Both methods find that alteration covers 7-8% and active outflow 1-3% of the survey region. It is unclear if the observed hydrothermal fluids are part of the fluid circulation network of the nearby Kick'em Jenny volcano or if a separate heat source is driving this flow. To test these two endmember cases, we use a 2D, finite-difference, marker-in-cell code to simulate hydrothermal circulation of a single-phase fluid within the oceanic crust. Parameters varied include the permeability structure (e.g., inclusion of a permeability barrier representing the collapse surface), the depth to the heat source beneath Kick'em Jenny, and the bathymetry. We will discuss results from the photomosaic analysis and our initial models.

Dynamical Localization for Unitary Anderson Models

NASA Astrophysics Data System (ADS)

Hamza, Eman; Joye, Alain; Stolz, Günter

2009-11-01

This paper establishes dynamical localization properties of certain families of unitary random operators on the d-dimensional lattice in various regimes. These operators are generalizations of one-dimensional physical models of quantum transport and draw their name from the analogy with the discrete Anderson model of solid state physics. They consist in a product of a deterministic unitary operator and a random unitary operator. The deterministic operator has a band structure, is absolutely continuous and plays the role of the discrete Laplacian. The random operator is diagonal with elements given by i.i.d. random phases distributed according to some absolutely continuous measure and plays the role of the random potential. In dimension one, these operators belong to the family of CMV-matrices in the theory of orthogonal polynomials on the unit circle. We implement the method of Aizenman-Molchanov to prove exponential decay of the fractional moments of the Green function for the unitary Anderson model in the following three regimes: In any dimension, throughout the spectrum at large disorder and near the band edges at arbitrary disorder and, in dimension one, throughout the spectrum at arbitrary disorder. We also prove that exponential decay of fractional moments of the Green function implies dynamical localization, which in turn implies spectral localization. These results complete the analogy with the self-adjoint case where dynamical localization is known to be true in the same three regimes.

Kinematic and EMG data during underwater dolphin kick change while synchronizing with or without synchronization of kick frequency with the beat of a metronome.

PubMed

Yamakawa, Keisuke Kobayashi; Shimojo, Hirofumi; Takagi, Hideki; Tsubakimoto, Shozo; Sengoku, Yasuo

2017-10-01

We investigated the effects of synchronizing kick frequency with the beat of a metronome on kinematic and electromyographic (EMG) parameters during the underwater dolphin kick as a pilot study related to the research that entitled " Effect of increased kick frequency on propelling efficiency and muscular co-activation during underwater dolphin kick" (Yamakawa et al., 2017) [1]. Seven collegiate female swimmers participated in this experiment. The participants conducted two underwater dolphin kick trials: swimming freely at maximum effort, and swimming while synchronizing the kick frequency of maximum effort with the beat of a metronome. The kinematic parameters during the underwater dolphin kick were calculated by 2-D motion analysis, and surface electromyographic measurements were taken from six muscles (rectus abdominis, erector spinae, rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius). The results revealed no significant differences in the kinematic and EMG parameters between trials of the two swimming techniques. Therefore, the action of synchronizing the kick frequency with the beat of a metronome did not affect movement or muscle activity during the underwater dolphin kick in this experiment.

Quantum and classical chaos in kicked coupled Jaynes-Cummings cavities

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

Hayward, A. L. C.; Greentree, Andrew D.

2010-06-15

We consider two Jaynes-Cummings cavities coupled periodically with a photon hopping term. The semiclassical phase space is chaotic, with regions of stability over some ranges of the parameters. The quantum case exhibits dynamic localization and dynamic tunneling between classically forbidden regions. We explore the correspondence between the classical and quantum phase space and propose an implementation in a circuit QED system.

Free kick instead of cross-validation in maximum-likelihood refinement of macromolecular crystal structures

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

Pražnikar, Jure; University of Primorska,; Turk, Dušan, E-mail: dusan.turk@ijs.si

2014-12-01

The maximum-likelihood free-kick target, which calculates model error estimates from the work set and a randomly displaced model, proved superior in the accuracy and consistency of refinement of crystal structures compared with the maximum-likelihood cross-validation target, which calculates error estimates from the test set and the unperturbed model. The refinement of a molecular model is a computational procedure by which the atomic model is fitted to the diffraction data. The commonly used target in the refinement of macromolecular structures is the maximum-likelihood (ML) function, which relies on the assessment of model errors. The current ML functions rely on cross-validation. Theymore » utilize phase-error estimates that are calculated from a small fraction of diffraction data, called the test set, that are not used to fit the model. An approach has been developed that uses the work set to calculate the phase-error estimates in the ML refinement from simulating the model errors via the random displacement of atomic coordinates. It is called ML free-kick refinement as it uses the ML formulation of the target function and is based on the idea of freeing the model from the model bias imposed by the chemical energy restraints used in refinement. This approach for the calculation of error estimates is superior to the cross-validation approach: it reduces the phase error and increases the accuracy of molecular models, is more robust, provides clearer maps and may use a smaller portion of data for the test set for the calculation of R{sub free} or may leave it out completely.« less

Relation Between Iliopsoas Cross-sectional Area and Kicked Ball Speed in Soccer Players.

PubMed

Wakahara, Taku; Chiba, Manabu

2018-05-14

This study aimed to investigate the relationship between the maximal anatomical cross-sectional area (ACSA) of the iliopsoas muscle and ball speed in side-foot and instep kicks. The ACSA of the psoas major and iliacus was measured in 29 male collegiate soccer players by using magnetic resonance imaging. They performed maximal side-foot and instep kicks to a stationary ball. The kicked ball speed was measured with a high-speed camera. Ball speed in the side-foot and instep kicks was significantly correlated with body height (side-foot kick: r=0.650, P<0.001; instep kick: r=0.583, P<0.001). After adjustment for body height, the maximal ACSA of the psoas major was significantly correlated with ball speed in the side-foot kick (r=0.441, P=0.017), but not in the instep kick. The maximal ACSA of the iliacus was not correlated with ball speed in side-foot or instep kicks, even after adjustment for body height. Our results suggest that: 1) body height is a significant determinant of the ball speed in side-foot and instep kicks, and 2) for a given body height, the maximal ACSA of the dominant psoas major is a factor that affects the ball speed in side-foot kick. © Georg Thieme Verlag KG Stuttgart · New York.

ACCRETION DISKS AROUND KICKED BLACK HOLES: POST-KICK DYNAMICS

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

Ponce, Marcelo; Faber, Joshua A.; Lombardi, James C., E-mail: mponce@astro.rit.edu, E-mail: jafsma@rit.edu, E-mail: jalombar@allegheny.edu

2012-01-20

Numerical calculations of merging black hole binaries indicate that asymmetric emission of gravitational radiation can kick the merged black hole at up to thousands of km s{sup -1}, and a number of systems have been observed recently whose properties are consistent with an active galactic nucleus containing a supermassive black hole moving with substantial velocity with respect to its broader accretion disk. We study here the effect of an impulsive kick delivered to a black hole on the dynamical evolution of its accretion disk using a smoothed particle hydrodynamics code, focusing attention on the role played by the kick anglemore » with respect to the orbital angular momentum vector of the pre-kicked disk. We find that for more vertical kicks, for which the angle between the kick and the normal vector to the disk {theta} {approx}< 30 Degree-Sign , a gap remains present in the inner disk, in accordance with the prediction from an analytic collisionless Keplerian disk model, while for more oblique kicks with {theta} {approx}> 45 Degree-Sign , matter rapidly accretes toward the black hole. There is a systematic trend for higher potential luminosities for more oblique kick angles for a given black hole mass, disk mass, and kick velocity, and we find large amplitude oscillations in time in the case of a kick oriented 60 Degree-Sign from the vertical.« less

Mechanical analysis of the roundhouse kick according to height and distance in taekwondo.

PubMed

Estevan, I; Falco, C

2013-12-01

Competition regulation in taekwondo has experienced several changes during the last few years, for example, kicks to the head score more points than kicks to the chest. In addition, some external factors such as the height of target and execution distance seem to affect the kick performance. The aim of this study was to analyse selected biomechanical parameters (impact force, reaction time, and execution time) according to the height and execution distance in two different male groups (experts (n = 12) and novices (n = 21)). Athletes kicked twice from every execution distance (short, normal and long) and towards two different heights of target (chest and head) in a random order. Novices kicked to the head with a longer reaction time than to the chest (p < 0.05) but experts were able to kick with similar performance for both heights. From short and normal distances experts kicked with similar performance; whereas from the normal distance novices had longer reaction and execution time than from the short distance (p < 0.05). In conclusion, in counterattacking situations, experts should perform the roundhouse kick to the head instead of to the chest, because it produces better scores with similar performance; whereas novice athletes should avoid kicking to the head because they are not able to kick with similar performance. Moreover, it is recommended that during counterattacks higher-level taekwondo athletes should intend to kick from normal distances.

MECHANICAL ANALYSIS OF THE ROUNDHOUSE KICK ACCORDING TO HEIGHT AND DISTANCE IN TAEKWONDO

PubMed Central

Falco, C.

2013-01-01

Competition regulation in taekwondo has experienced several changes during the last few years, for example, kicks to the head score more points than kicks to the chest. In addition, some external factors such as the height of target and execution distance seem to affect the kick performance. The aim of this study was to analyse selected biomechanical parameters (impact force, reaction time, and execution time) according to the height and execution distance in two different male groups (experts (n = 12) and novices (n = 21)). Athletes kicked twice from every execution distance (short, normal and long) and towards two different heights of target (chest and head) in a random order. Novices kicked to the head with a longer reaction time than to the chest (p < 0.05) but experts were able to kick with similar performance for both heights. From short and normal distances experts kicked with similar performance; whereas from the normal distance novices had longer reaction and execution time than from the short distance (p < 0.05). In conclusion, in counterattacking situations, experts should perform the roundhouse kick to the head instead of to the chest, because it produces better scores with similar performance; whereas novice athletes should avoid kicking to the head because they are not able to kick with similar performance. Moreover, it is recommended that during counterattacks higher-level taekwondo athletes should intend to kick from normal distances. PMID:24744499

Quadratic time dependent Hamiltonians and separation of variables

NASA Astrophysics Data System (ADS)

Anzaldo-Meneses, A.

2017-06-01

Time dependent quantum problems defined by quadratic Hamiltonians are solved using canonical transformations. The Green's function is obtained and a comparison with the classical Hamilton-Jacobi method leads to important geometrical insights like exterior differential systems, Monge cones and time dependent Gaussian metrics. The Wei-Norman approach is applied using unitary transformations defined in terms of generators of the associated Lie groups, here the semi-direct product of the Heisenberg group and the symplectic group. A new explicit relation for the unitary transformations is given in terms of a finite product of elementary transformations. The sequential application of adequate sets of unitary transformations leads naturally to a new separation of variables method for time dependent Hamiltonians, which is shown to be related to the Inönü-Wigner contraction of Lie groups. The new method allows also a better understanding of interacting particles or coupled modes and opens an alternative way to analyze topological phases in driven systems.

Statistical and dynamical properties of a dissipative kicked rotator

NASA Astrophysics Data System (ADS)

Oliveira, Diego F. M.; Leonel, Edson D.

2014-11-01

Some dynamical and statistical properties for a conservative as well as the dissipative problem of relativistic particles in a waveguide are considered. For the first time, two different types of dissipation namely: (i) due to viscosity and; (ii) due to inelastic collision (upon the kick) are considered individually and acting together. For the first case, and contrary to what is expected for the original Zaslavsky’s relativistic model, we show there is a critical parameter where a transition from local to global chaos occurs. On the other hand, after considering the introduction of dissipation also on the kick, the structure of the phase space changes in the sense that chaotic and periodic attractors appear. We study also the chaotic sea by using scaling arguments and we proposed an analytical argument to reinforce the validity of the scaling exponents obtained numerically. In principle such an approach can be extended to any two-dimensional map. Finally, based on the Lyapunov exponent, we show that the parameter space exhibits infinite families of self-similar shrimp-shape structures, corresponding to periodic attractors, embedded in a large region corresponding to chaotic attractors.

Role of Vertical Jumps and Anthropometric Variables in Maximal Kicking Ball Velocities in Elite Soccer Players

PubMed Central

Rodríguez-Lorenzo, Lois; Fernandez-del-Olmo, Miguel; Sanchez-Molina, José Andrés

2016-01-01

Abstract Kicking is one of the most important skills in soccer and the ability to achieve ma ximal kicking velocity with both legs leads to an advantage for the soccer player. This study examined the relationship be tween kicking ball velocity with both legs using anthropometric measurements and vertical jumps (a squat jump (SJ); a countermovement jump without (CMJ) and with the arm swing (CMJA) and a reactive jump (RJ)). Anthropome tric measurements did not correlate with kicking ball velocity. Vertical jumps correlated significantly with kicking ball velocity using the dominant leg only (r = .47, r = .58, r = .44, r = .51, for SJ, CMJ, CMJA and RJ, respectively) . Maximal kicking velocity with the dominant leg was significantly higher than with the non-dominant leg (t = 18.0 4, p < 0.001). Our results suggest that vertical jumps may be an optimal test to assess neuromuscular skills involved in kicking at maximal speed. Lack of the relationship between vertical jumps and kicking velocity with the non-dominant leg may reflect a difficulty to exhibit the neuromuscular skills during dominant leg kicking. PMID:28149419

Kick-Sledding: An Outdoor Activity for Everyone.

ERIC Educational Resources Information Center

Wilson, Susan

1994-01-01

Kick-sledding is an outdoor activity that originated in Scandinavia. Kick-sleds may be used on snowy roads, cross-country ski trails, and frozen lakes by anyone, including seniors, children, and mothers with babies. To ride a kick-sled, you stand holding onto a bar across the back of a chair attached to runners and propel yourself by kicking. (LP)

Effect of Postactivation Potentiation Induced by Elastic Resistance on Kinematics and Performance in a Roundhouse Kick of Trained Martial Arts Practitioners.

PubMed

Aandahl, Håkon S; Von Heimburg, Erna; Van den Tillaar, Roland

2018-04-01

Aandahl, HS, Von Heimburg, E, and Van den Tillaar, R. Effect of postactivation potentiation induced by elastic resistance on kinematics and performance in a roundhouse kick of trained martial arts practitioners. J Strength Cond Res 32(4): 990-996, 2018-The aim of this study was to examine whether kicking with elastic resistance during warm-up could initiate postactivation potentiation (PAP), and thereby positively influence kinematics and performance on subsequent explosive roundhouse kicking. Five women and 11 men (n = 16) with a background in kickboxing (n = 10) or taekwondo (n = 6) performed 2 warm-up strategies with 3 subsequent test kicks 5-8 minutes after a PAP-inducing exercise. Kicking performance, defined as roundhouse kicking velocity with the foot, was measured using 3D motion capture (500 Hz) with a 15 marker lower-body 3D model. In addition, electromyography of the prime movers-vastus lateralis, vastus medialis, and rectus femoris muscles-was measured to confirm the presence of PAP. Kicking velocity of the foot increased by 3.3% after performing a warming-up strategy including kicking with elastic resistance (p = 0.009, η = 0.32). Increases were also recorded in muscle activity in vastus medialis (35.2%, p = 0.05, η = 0.18) and rectus femoris (43.9%, p = 0.04, η = 0.20). These findings indicate that performing a warm-up strategy including kicking with elastic resistance can have a positive effect on kicking performance in a roundhouse kick.

Supersymmetric symplectic quantum mechanics

NASA Astrophysics Data System (ADS)

de Menezes, Miralvo B.; Fernandes, M. C. B.; Martins, Maria das Graças R.; Santana, A. E.; Vianna, J. D. M.

2018-02-01

Symplectic Quantum Mechanics SQM considers a non-commutative algebra of functions on a phase space Γ and an associated Hilbert space HΓ to construct a unitary representation for the Galilei group. From this unitary representation the Schrödinger equation is rewritten in phase space variables and the Wigner function can be derived without the use of the Liouville-von Neumann equation. In this article we extend the methods of supersymmetric quantum mechanics SUSYQM to SQM. With the purpose of applications in quantum systems, the factorization method of the quantum mechanical formalism is then set within supersymmetric SQM. A hierarchy of simpler hamiltonians is generated leading to new computation tools for solving the eigenvalue problem in SQM. We illustrate the results by computing the states and spectra of the problem of a charged particle in a homogeneous magnetic field as well as the corresponding Wigner function.

Fast-kick-off monotonically convergent algorithm for searching optimal control fields

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

Liao, Sheng-Lun; Ho, Tak-San; Rabitz, Herschel

2011-09-15

This Rapid Communication presents a fast-kick-off search algorithm for quickly finding optimal control fields in the state-to-state transition probability control problems, especially those with poorly chosen initial control fields. The algorithm is based on a recently formulated monotonically convergent scheme [T.-S. Ho and H. Rabitz, Phys. Rev. E 82, 026703 (2010)]. Specifically, the local temporal refinement of the control field at each iteration is weighted by a fractional inverse power of the instantaneous overlap of the backward-propagating wave function, associated with the target state and the control field from the previous iteration, and the forward-propagating wave function, associated with themore » initial state and the concurrently refining control field. Extensive numerical simulations for controls of vibrational transitions and ultrafast electron tunneling show that the new algorithm not only greatly improves the search efficiency but also is able to attain good monotonic convergence quality when further frequency constraints are required. The algorithm is particularly effective when the corresponding control dynamics involves a large number of energy levels or ultrashort control pulses.« less

OPERATIONAL EXPERIENCE WITH BEAM ABORT SYSTEM FOR SUPERCONDUCTING UNDULATOR QUENCH MITIGATION*

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

Harkay, Katherine C.; Dooling, Jeffrey C.; Sajaev, Vadim

A beam abort system has been implemented in the Advanced Photon Source storage ring. The abort system works in tandem with the existing machine protection system (MPS), and its purpose is to control the beam loss location and, thereby, minimize beam loss-induced quenches at the two superconducting undulators (SCUs). The abort system consists of a dedicated horizontal kicker designed to kick out all the bunches in a few turns after being triggered by MPS. The abort system concept was developed on the basis of single- and multi-particle tracking simulations using elegant and bench measurements of the kicker pulse. Performance ofmore » the abort system—kick amplitudes and loss distributions of all bunches—was analyzed using beam position monitor (BPM) turn histories, and agrees reasonably well with the model. Beam loss locations indicated by the BPMs are consistent with the fast fiber-optic beam loss monitor (BLM) diagnostics described elsewhere [1,2]. Operational experience with the abort system, various issues that were encountered, limitations of the system, and quench statistics are described.« less

Development for a supercompact X -band pulse compression system and its application at SLAC

DOE PAGES

Wang, Juwen W.; Tantawi, Sami G.; Xu, Chen; ...

2017-11-09

Here, we have successfully designed, fabricated, installed, and tested a super compact X -band SLAC Energy Doubler system at SLAC. It is composed of an elegant 3 dB coupler–mode converter–polarizer coupled to a single spherical energy storage cavity with high Q 0 of 94000 and a diameter less than 12 cm. The available rf peak power of 50 MW can be compressed to a peak average power of more than 200 MW in order to double the kick for the electron bunches in a rf transverse deflector system and greatly improve the measurement resolution of both the electron bunches andmore » the x-ray free-electron laser pulses. The design physics and fabrication as well as the measurement results will be presented in detail. High-power operation has demonstrated the excellent performance of this rf compression system without rf breakdown, sign of pulse heating, and rf radiation.« less

Development for a supercompact X -band pulse compression system and its application at SLAC

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

Wang, Juwen W.; Tantawi, Sami G.; Xu, Chen

Here, we have successfully designed, fabricated, installed, and tested a super compact X -band SLAC Energy Doubler system at SLAC. It is composed of an elegant 3 dB coupler–mode converter–polarizer coupled to a single spherical energy storage cavity with high Q 0 of 94000 and a diameter less than 12 cm. The available rf peak power of 50 MW can be compressed to a peak average power of more than 200 MW in order to double the kick for the electron bunches in a rf transverse deflector system and greatly improve the measurement resolution of both the electron bunches andmore » the x-ray free-electron laser pulses. The design physics and fabrication as well as the measurement results will be presented in detail. High-power operation has demonstrated the excellent performance of this rf compression system without rf breakdown, sign of pulse heating, and rf radiation.« less

Integrability and nonintegrability of quantum systems. II. Dynamics in quantum phase space

NASA Astrophysics Data System (ADS)

Zhang, Wei-Min; Feng, Da Hsuan; Yuan, Jian-Min

1990-12-01

Based on the concepts of integrability and nonintegrability of a quantum system presented in a previous paper [Zhang, Feng, Yuan, and Wang, Phys. Rev. A 40, 438 (1989)], a realization of the dynamics in the quantum phase space is now presented. For a quantum system with dynamical group scrG and in one of its unitary irreducible-representation carrier spaces gerhΛ, the quantum phase space is a 2MΛ-dimensional topological space, where MΛ is the quantum-dynamical degrees of freedom. This quantum phase space is isomorphic to a coset space scrG/scrH via the unitary exponential mapping of the elementary excitation operator subspace of scrg (algebra of scrG), where scrH (⊂scrG) is the maximal stability subgroup of a fixed state in gerhΛ. The phase-space representation of the system is realized on scrG/scrH, and its classical analogy can be obtained naturally. It is also shown that there is consistency between quantum and classical integrability. Finally, a general algorithm for seeking the manifestation of ``quantum chaos'' via the classical analogy is provided. Illustrations of this formulation in several important quantum systems are presented.

A study of the feasibility of introducing therapeutic touch into the operative environment with patients undergoing cerebral angiography.

PubMed

Madrid, Mary M; Barrett, Elizabeth A M; Winstead-Fry, Patricia

2010-09-01

The purpose of this pilot study was to determine whether Therapeutic Touch (TT) can be effectively used in the operative setting and whether it could produce positive outcomes in the period from cerebral angiography to discharge. The specific outcomes to be assessed were blood pressure, pulse, and respirations. TT is an intervention that involves the intentional direction of energy for the purpose of healing. The present study was developed within the conceptual framework of Rogers's model of unitary human beings. Data were collected at a center for endovascular surgery. The participants were 40 men and women aged between 18 and 80 years who were referred to the center for cerebral angiograms. The participants were English-speaking, ambulatory patients, with no history of prior cerebral angiograms and no psychiatric diagnosis. The design was a randomized, single-blind experiment. The research data were collected in the normal course of the angiogram procedure and recovery room. The blood pressure, pulse, and respirations were routinely noted before, during, and after the procedure. The study was significant in three aspects: (a) it was the first study to develop a protocol for delivering TT in the preoperative course of neurological patients, (b) the study is conceptualized within Rogers's conceptual model of unitary human beings, and (c) the study explored the impact of TT on selected outcomes in endovascular patients. A protocol for delivering TT in the operative setting was successfully developed and implemented. The efficacy of TT on the blood pressure, respirations, and pulse of the experimental group was not statistically significant. The reasons for this finding are explored, and suggestions are made for future research.

Prototyping method for Bragg-type atom interferometers

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

Benton, Brandon; Krygier, Michael; Heward, Jeffrey

2011-10-15

We present a method for rapid modeling of new Bragg ultracold atom-interferometer (AI) designs useful for assessing the performance of such interferometers. The method simulates the overall effect on the condensate wave function in a given AI design using two separate elements. These are (1) modeling the effect of a Bragg pulse on the wave function and (2) approximating the evolution of the wave function during the intervals between the pulses. The actual sequence of these pulses and intervals is then followed to determine the approximate final wave function from which the interference pattern can be calculated. The exact evolutionmore » between pulses is assumed to be governed by the Gross-Pitaevskii (GP) equation whose solution is approximated using a Lagrangian variational method to facilitate rapid estimation of performance. The method presented here is an extension of an earlier one that was used to analyze the results of an experiment [J. E. Simsarian et al., Phys. Rev. Lett. 85, 2040 (2000)], where the phase of a Bose-Einstein condensate was measured using a Mach-Zehnder-type Bragg AI. We have developed both 1D and 3D versions of this method and we have determined their validity by comparing their predicted interference patterns with those obtained by numerical integration of the 1D GP equation and with the results of the above experiment. We find excellent agreement between the 1D interference patterns predicted by this method and those found by the GP equation. We show that we can reproduce all of the results of that experiment without recourse to an ad hoc velocity-kick correction needed by the earlier method, including some experimental results that the earlier model did not predict. We also found that this method provides estimates of 1D interference patterns at least four orders-of-magnitude faster than direct numerical solution of the 1D GP equation.« less

Floquet time crystal in the Lipkin-Meshkov-Glick model

NASA Astrophysics Data System (ADS)

Russomanno, Angelo; Iemini, Fernando; Dalmonte, Marcello; Fazio, Rosario

2017-06-01

In this work we discuss the existence of time-translation symmetry breaking in a kicked infinite-range-interacting clean spin system described by the Lipkin-Meshkov-Glick model. This Floquet time crystal is robust under perturbations of the kicking protocol, its existence being intimately linked to the underlying Z2 symmetry breaking of the time-independent model. We show that the model being infinite range and having an extensive amount of symmetry-breaking eigenstates is essential for having the time-crystal behavior. In particular, we discuss the properties of the Floquet spectrum, and show the existence of doublets of Floquet states which are, respectively, even and odd superposition of symmetry-broken states and have quasienergies differing of half the driving frequencies, a key essence of Floquet time crystals. Remarkably, the stability of the time-crystal phase can be directly analyzed in the limit of infinite size, discussing the properties of the corresponding classical phase space. Through a detailed analysis of the robustness of the time crystal to various perturbations we are able to map the corresponding phase diagram. We finally discuss the possibility of an experimental implementation by means of trapped ions.

Biomechanical Characteristics and Determinants of Instep Soccer Kick

PubMed Central

Kellis, Eleftherios; Katis, Athanasios

2007-01-01

Good kicking technique is an important aspect of a soccer player. Therefore, understanding the biomechanics of soccer kicking is particularly important for guiding and monitoring the training process. The purpose of this review was to examine latest research findings on biomechanics of soccer kick performance and identify weaknesses of present research which deserve further attention in the future. Being a multiarticular movement, soccer kick is characterised by a proximal-to-distal motion of the lower limb segments of the kicking leg. Angular velocity is maximized first by the thigh, then by the shank and finally by the foot. This is accomplished by segmental and joint movements in multiple planes. During backswing, the thigh decelerates mainly due to a motion-dependent moment from the shank and, to a lesser extent, by activation of hip muscles. In turn, forward acceleration of the shank is accomplished through knee extensor moment as well as a motion-dependent moment from the thigh. The final speed, path and spin of the ball largely depend on the quality of foot-ball contact. Powerful kicks are achieved through a high foot velocity and coefficient of restitution. Preliminary data indicate that accurate kicks are achieved through slower kicking motion and ball speed values. Key pointsSoccer kick is achieved through segmental and joint rotations in multiple planes and via the proximal-to-distal sequence of segmental angular velocities until ball impact. The quality of ball - foot impact and the mechanical behavior of the foot are also important determinants of the final speed, path and spin of the ball.Ball speed values during the maximum instep kick range from 18 to 35 msec-1 depending on various factors, such as skill level, age, approach angle and limb dominance.The main bulk of biomechanics research examined the biomechanics of powerful kicks, mostly under laboratory conditions. A powerful kick is characterized by the achievement of maximal ball speed. However, maximal ball speed does not guarantee a successful kick: in each case, the ball must reach the target. As already explained, when the player is instructed to hit the ball accurately, joint and segment velocities are lower as opposed to a fast and powerful kick performance. It is therefore apparent that future research should focus on biomechanics of fast but accurate kicking. PMID:24149324

Kinematic comparison of the preferred and non-preferred foot punt kick.

PubMed

Ball, Kevin A

2011-11-01

Kicking with the non-preferred leg is important in Australian Football and becoming important in the rugby codes. The aim of this study was to examine differences between preferred and non-preferred leg kicking in the drop punt kick. Seventeen elite Australian Football players performed kicks with the preferred and non-preferred leg. Optotrak Certus collected kinematic data of the kick leg and pelvis (200 Hz) from kick leg toe-off until ball contact. Foot speed, knee and shank angular velocity at ball contact, and pelvis range of motion were significantly larger for the preferred leg (P < 0.05). In contrast, hip and thigh angular velocity at ball contact and hip range of motion were significantly larger for the non-preferred leg. This indicates different movement patterns, with preferred-leg kicks making greater use of the pelvis, knee, and shank while non-preferred leg kicks rely relatively more on the hip and thigh (P < 0.05). Reasons for this difference might be due to locking degrees of freedom or sub-optimal sequencing in the non-preferred leg. The thigh-knee continuum identified by Ball ( 2008 ) was also evident in this study. Findings have implications for training non-preferred leg kicking for performance and injury prevention.

How Experts Practice: A Novel Test of Deliberate Practice Theory

ERIC Educational Resources Information Center

Coughlan, Edward K.; Williams, A. Mark; McRobert, Allistair P.; Ford, Paul R.

2014-01-01

Performance improvement is thought to occur through engagement in deliberate practice. Deliberate practice is predicted to be challenging, effortful, and not inherently enjoyable. Expert and intermediate level Gaelic football players executed two types of kicks during an acquisition phase and pre-, post-, and retention tests. During acquisition,…

Multijoint kinetic chain analysis of knee extension during the soccer instep kick.

PubMed

Naito, Kozo; Fukui, Yosuke; Maruyama, Takeo

2010-04-01

Although previous studies have shown that motion-dependent interactions between adjacent segments play an important role in producing knee extension during the soccer instep kick, detailed knowledge about the mechanisms underlying those interactions is lacking. The present study aimed to develop a 3-D dynamical model for the multijoint kinetic chain of the instep kick in order to quantify the contributions of the causal dynamical factors to the production of maximum angular velocity during knee extension. Nine collegiate soccer players volunteered to participate in the experiment and performed instep kicking movements while 3-D positional data and the ground reaction force were measured. A dynamical model was developed in the form of a linked system containing 8 segments and 18 joint rotations, and the knee extension/flexion motion was decomposed into causal factors related to muscular moment, gyroscopic moment, centrifugal force, Coriolis force, gravity, proximal endpoint linear acceleration, and external force-dependent terms. The rapid knee extension during instep kicking was found to result almost entirely from kicking leg centrifugal force, trunk rotation muscular moment, kicking leg Coriolis force, and trunk rotation gyroscopic-dependent components. Based on the finding that rapid knee extension during instep kicking stems from multiple dynamical factors, it is suggested that the multijoint kinetic chain analysis used in the present study is more useful for achieving a detailed understanding of the cause of rapid kicking leg movement than the previously used 2-D, two-segment kinetic chain model. The present results also indicated that the centrifugal effect due to the kicking hip flexion angular velocity contributed substantially to the generation of a rapid knee extension, suggesting that the adjustment between the kicking hip flexion angular velocity and the leg configuration (knee flexion angle) is more important for effective instep kicking than other joint kinematics.

Supersonic dynamic stability characteristics of the test technique demonstrator NASP configuration

NASA Technical Reports Server (NTRS)

Dress, David A.; Boyden, Richmond P.; Cruz, Christopher I.

1992-01-01

Wind tunnel tests of a National Aero-Space Plane (NASP) configuration were conducted in both test sections of the Langley Unitary Plan Wind Tunnel. The model used is a Langley designed blended body NASP configuration. Dynamic stability characteristics were measured on this configuration at Mach numbers of 2.0, 2.5, 3.5, and 4.5. In addition to tests of the baseline configuration, component buildup tests were conducted. The test results show that the baseline configuration generally has positive damping about all three axes with only isolated exceptions. In addition, there was generally good agreement between the in-pulse dynamic parameters and the corresponding static data which were measured during another series of tests in the Unitary Plan Wind Tunnel. Also included are comparisons of the experimental damping parameters with results from the engineering predictive code APAS (Aerodynamic Preliminary Analysis System). These comparisons show good agreement at low angles of attack; however, the comparisons are generally not as good at the higher angles of attack.

Collective modes of an imbalanced unitary Fermi gas

NASA Astrophysics Data System (ADS)

Hofmann, Johannes; Chevy, Frédéric; Goulko, Olga; Lobo, Carlos

2018-03-01

We study theoretically the collective mode spectrum of a strongly imbalanced two-component unitary Fermi gas in a cigar-shaped trap, where the minority species forms a gas of polarons. We describe the collective breathing mode of the gas in terms of the Fermi-liquid kinetic equation taking collisions into account using the method of moments. Our results for the frequency and damping of the longitudinal in-phase breathing mode are in good quantitative agreement with an experiment by Nascimbène et al. [Phys. Rev. Lett. 103, 170402 (2009), 10.1103/PhysRevLett.103.170402] and interpolate between a hydrodynamic and a collisionless regime as the polarization is increased. A separate out-of phase breathing mode, which for a collisionless gas is sensitive to the effective mass of the polaron, however, is strongly damped at finite temperature, whereas the experiment observes a well-defined oscillation.

Neutron Star Natal Kick and Jets in Core Collapse Supernovae

NASA Astrophysics Data System (ADS)

Bear, Ealeal; Soker, Noam

2018-03-01

We measure the angle between the neutron star (NS) natal kick direction and the inferred direction of jets according to the morphology of 12 core collapse supernova remnants (SNR), and find that the distribution is almost random, but missing small angles. The 12 SNRs are those for which we could both identify morphological features that we can attribute to jets and for which the direction of the NS natal kick is given in the literature. Unlike some claims for spin-kick alignment, here we rule out jet-kick alignment. We discuss the cumulative distribution function of the jet-kick angles under the assumption that dense clumps that are ejected by the explosion accelerate the NS by the gravitational attraction, and suggest that the jet feedback explosion mechanism might in principle account for the distribution of jet-kick angles.

Evaluation of goal kicking performance in international rugby union matches.

PubMed

Quarrie, Kenneth L; Hopkins, Will G

2015-03-01

Goal kicking is an important element in rugby but has been the subject of minimal research. To develop and apply a method to describe the on-field pattern of goal-kicking and rank the goal kicking performance of players in international rugby union matches. Longitudinal observational study. A generalized linear mixed model was used to analyze goal-kicking performance in a sample of 582 international rugby matches played from 2002 to 2011. The model adjusted for kick distance, kick angle, a rating of the importance of each kick, and venue-related conditions. Overall, 72% of the 6769 kick attempts were successful. Forty-five percent of points scored during the matches resulted from goal kicks, and in 5.7% of the matches the result of the match hinged on the outcome of a kick attempt. There was an extremely large decrease in success with increasing distance (odds ratio for two SD distance 0.06, 90% confidence interval 0.05-0.07) and a small decrease with increasingly acute angle away from the mid-line of the goal posts (odds ratio for 2 SD angle, 0.44, 0.39-0.49). Differences between players were typically small (odds ratio for 2 between-player SD 0.53, 0.45-0.65). The generalized linear mixed model with its random-effect solutions provides a tool for ranking the performance of goal kickers in rugby. This modelling approach could be applied to other performance indicators in rugby and in other sports in which discrete outcomes are measured repeatedly on players or teams. Copyright © 2015. Published by Elsevier Ltd.

Radio-Frequency-Controlled Cold Collisions and Universal Properties of Unitary Bose Gases

NASA Astrophysics Data System (ADS)

Ding, Yijue

This thesis investigates two topics: ultracold atomic collisions in a radio-frequency field and universal properties of a degenerate unitary Bose gas. One interesting point of the unitary Bose gas is that the system has only one length scale, that is, the average interparticle distance. This single parameter determines all properties of the gas, which is called the universality of the system. We first introduce a renormalized contact interaction to extend the validity of the zero-range interaction to large scattering lengths. Then this renormalized interaction is applied to many-body theories to determined those universal relations of the system. From the few-body perspective, we discuss the scattering between atoms in a single-color radio-frequency field. Our motivation is proposing the radio-frequency field as an effective tool to control interactions between cold atoms. Such a technique may be useful in future experiments such as creating phase transitions in spinor condensates. We also discuss the formation of ultracold molecules using radio-freqency fields from a time-dependent approach.

Nonequilibrium Phase Transition in a Periodically Driven XY Spin Chain

NASA Astrophysics Data System (ADS)

Prosen, Tomaž; Ilievski, Enej

2011-08-01

We present a general formulation of Floquet states of periodically time-dependent open Markovian quasifree fermionic many-body systems in terms of a discrete Lyapunov equation. Illustrating the technique, we analyze periodically kicked XY spin-(1)/(2) chain which is coupled to a pair of Lindblad reservoirs at its ends. A complex phase diagram is reported with reentrant phases of long range and exponentially decaying spin-spin correlations as some of the system’s parameters are varied. The structure of phase diagram is reproduced in terms of counting nontrivial stationary points of Floquet quasiparticle dispersion relation.

Black Hole Kicks as New Gravitational Wave Observables.

PubMed

Gerosa, Davide; Moore, Christopher J

2016-07-01

Generic black hole binaries radiate gravitational waves anisotropically, imparting a recoil, or kick, velocity to the merger remnant. If a component of the kick along the line of sight is present, gravitational waves emitted during the final orbits and merger will be gradually Doppler shifted as the kick builds up. We develop a simple prescription to capture this effect in existing waveform models, showing that future gravitational wave experiments will be able to perform direct measurements, not only of the black hole kick velocity, but also of its accumulation profile. In particular, the eLISA space mission will measure supermassive black hole kick velocities as low as ∼500  km s^{-1}, which are expected to be a common outcome of black hole binary coalescence following galaxy mergers. Black hole kicks thus constitute a promising new observable in the growing field of gravitational wave astronomy.

Survival resonances in an atom-optics system driven by temporally and spatially periodic dissipation

NASA Astrophysics Data System (ADS)

Chai, Shijie; Fekete, Julia; McDowall, Peter; Coop, Simon; Lindballe, Thue; Andersen, Mikkel F.

2018-03-01

We investigate laser-cooled atoms periodically driven by pulsed standing waves of light tuned close to an open atomic transition. This nonunitary system displays survival resonances for certain driving frequencies. The survival resonances emerge as a result of the matter-wave Talbot-Lau effect, similar to the Talbot effect causing quantum resonances in the atom optics δ -kicked rotor. Since the Talbot-Lau effect occurs for incoherent waves, the survival resonances can be observed using thermal atoms. A microlensing effect can enhance the height and incisiveness of the resonances. This may find applications in precision measurements.

Criticality in the quantum kicked rotor with a smooth potential.

PubMed

Dutta, Rina; Shukla, Pragya

2008-09-01

We investigate the possibility of an Anderson-type transition in the quantum kicked rotor with a smooth potential due to dynamical localization of the wave functions. Our results show the typical characteristics of a critical behavior, i.e., multifractal eigenfunctions and a scale-invariant level statistics at a critical kicking strength which classically corresponds to a mixed regime. This indicates the existence of a localization to delocalization transition in the quantum kicked rotor. Our study also reveals the possibility of other types of transition in the quantum kicked rotor, with a kicking strength well within the strongly chaotic regime. These transitions, driven by the breaking of exact symmetries, e.g., time reversal and parity, are similar to weak-localization transitions in disordered metals.

Localization of Unitary Braid Group Representations

NASA Astrophysics Data System (ADS)

Rowell, Eric C.; Wang, Zhenghan

2012-05-01

Governed by locality, we explore a connection between unitary braid group representations associated to a unitary R-matrix and to a simple object in a unitary braided fusion category. Unitary R-matrices, namely unitary solutions to the Yang-Baxter equation, afford explicitly local unitary representations of braid groups. Inspired by topological quantum computation, we study whether or not it is possible to reassemble the irreducible summands appearing in the unitary braid group representations from a unitary braided fusion category with possibly different positive multiplicities to get representations that are uniformly equivalent to the ones from a unitary R-matrix. Such an equivalence will be called a localization of the unitary braid group representations. We show that the q = e π i/6 specialization of the unitary Jones representation of the braid groups can be localized by a unitary 9 × 9 R-matrix. Actually this Jones representation is the first one in a family of theories ( SO( N), 2) for an odd prime N > 1, which are conjectured to be localizable. We formulate several general conjectures and discuss possible connections to physics and computer science.

Residual Field Correction of Pulsed Bending Magnet

NASA Astrophysics Data System (ADS)

Takano, Junpei; Igarashi, Susumu; Kamikubota, Norihiko; Meigo, Shin-ichiro; Sato, Kenichi; Shirakata, Masashi; Yamada, Shuei

The Japan Proton Accelerator Research Complex (J-PARC) has an accelerator chain, Linac, Rapid Cycling Synchrotron (RCS), and Main Ring (MR). The RCS accelerates the proton beam up to 3 GeV every 40 msec. After the beam is extracted from the RCS, it is delivered to a beam transport line, which is 3NBT for the Material and Life Science Experimental Facility (MLF). Some bunches of the proton beam are bended from the 3NBT to another beam transport line, which is 3-50BT for the MR, by using a pulsed bending magnet (PB) [1]. However, the beam orbit in the 3NBT is kicked by the residual magnetic field of the PB. In order to correct the residual magnetic field, additional coils had been wound on the PB poles. As a result of scanning the current pattern of the correction coils, the orbit distortion in the 3NBT has been reduced.

Pseudochaos and anomalous transport: A study on saw-tooth map

NASA Astrophysics Data System (ADS)

Fan, Rong

The observation of chaotic dynamics in digital filter in late 1980s propelled the interest in piecewise linear map beyond the border of theoretical electrical engineering. Also, during last two decades, various physical models and phenomena, such as stochastic web and sticky orbits, not only broadened our knowledge of chaos but also urged us to further our understanding of meaning of chaos and randomness. In this dissertation, a piecewise linear kicked oscillator model: saw-tooth map, is studied as an example of pseudochaos. Physically, kicked oscillator model describes one-dimensional harmonic oscillator effected by delta-like kicks from external force source at certain fixed frequency. Starting from a special case of global periodicity, numerical investigations were carefully carried out in two cases that deviate from global periodicity. We observe the appearance of stochastic web structure and accompanying erratic dynamical behavior in the system that can't be fully explained by the classical Kolmogorov-Arnold-Moser theorem. Also anomalous transport occurs in both cases. We perform accurate analysis of Poincare recurrences and reconstruct the probability density function of Poincare recurrence times, which suggests a relation between the transport and the Poincare recurrence exponents. Saw-tooth map has non-uniform phase space, in which domains of regular dynamics and domains of chaotic dynamics are intertwined. The large-scale dynamics of the system is hugely impacted by the heterogeneity of the phase space, especially by the existence of hierarchy of periodic islands. We carefully study the characteristics of phase space and numerically compute fractal dimensions of the so-called exceptional set Delta in both cases. Our results suggest that the fractal dimension is strictly less than 2 and that the fractal structures are unifractal rather than multifractal. We present a phenomenological theoretical framework of Fractional Kinetic Equation (FKE) and Renormalization Group of Kinetics (RGK). FKE, which is fractional generalization of the Fokker-Planck-Kolmogorov equation, adopts the fractality of time and space and serves probabilistic description of chaos in Hamiltonian systems. RGK bridges the self-similar structure in phase space and large-scale behavior of the dynamics, and establishes relationships among fractality, transport and Poincare recurrences.

Recoiling from a Kick in the Head-On Case

NASA Technical Reports Server (NTRS)

Choi, Dae-Il; Kelly, Bernard J.; Boggs, William D.; Baker, John G.; Centrella, Joan; Van Meter, James

2007-01-01

Recoil "kicks" induced by gravitational radiation are expected in the inspiral and merger of black holes. Recently the numerical relativity community has begun to measure the significant kicks found when both unequal masses and spins are considered. Because understanding the cause and magnitude of each component of this kick may be complicated in inspiral simulations, we consider these effects in the context of a simple test problem. We study recoils from collisions of binaries with initially head-on trajectories, starting with the simplest case of equal masses with no spin; adding spin and varying the mass ratio, both separately and jointly. We find spin-induced recoils to be significant even in head-on configurations. Additionally, it appears that the scaling of transverse kicks with spins is consistent with post-Newtonian (PN) theory, even though the kick is generated in the nonlinear merger interaction, where PN theory should not apply. This suggests that a simple heuristic description might be effective in the estimation of spin-kicks.

Test of a General Formula for Black Hole Gravitational Wave Kicks

NASA Technical Reports Server (NTRS)

van Meter, James R.; Miller, M. Coleman; Baker, John G.; Boggs, William D.; Kelly, Bernard J.

2010-01-01

Although the gravitational wave kick velocity in the orbital plane of coalescing black holes has been understood for some time, apparently conflicting formulae have been proposed for the dominant outof- plane kick, each a good fit to different data sets. This is important to resolve because it is only the out-of-plane kicks that can reach more than 500 km s-l and can thus eject merged remnants from galaxies. Using a different ansatz for the out-of-plane kick, we show that we can fit almost all existing data to better than 5%. This is good enough for any astrophysical calculation and shows that the previous apparent conflict was only because the two data sets explored different aspects of the kick parameter space.

Transmitter release modulation by intracellular Ca2+ buffers in facilitating and depressing nerve terminals of pyramidal cells in layer 2/3 of the rat neocortex indicates a target cell-specific difference in presynaptic calcium dynamics

PubMed Central

Rozov, A; Burnashev, N; Sakmann, B; Neher, E

2001-01-01

In connections formed by nerve terminals of layer 2/3 pyramidal cells onto bitufted interneurones in young (postnatal day (P)14–15) rat somatosensory cortex, the efficacy and reliability of synaptic transmission were low. At these connections release was facilitated by paired-pulse stimulation (at 10 Hz). In connections formed by terminals of layer 2/3 pyramids with multipolar interneurones efficacy and reliability were high and release was depressed by paired-pulse stimulation. In both types of terminal, however, the voltage-dependent Ca2+ channels that controlled transmitter release were predominantly of the P/Q- and N-subtypes. The relationship between unitary EPSP amplitude and extracellular calcium concentration ([Ca2+]o) was steeper for facilitating than for depressing terminals. Fits to a Hill equation with nH= 4 indicated that the apparent KD of the Ca2+ sensor for vesicle release was two- to threefold lower in depressing terminals than in facilitating ones. Intracellular loading of pyramidal neurones with the fast and slowly acting Ca2+ buffers BAPTA and EGTA differentially reduced transmitter release in these two types of terminal. Unitary EPSPs evoked by pyramidal cell stimulation in bitufted cells were reduced by presynaptic BAPTA and EGTA with half-effective concentrations of ∼0.1 and ∼1 mm, respectively. Unitary EPSPs evoked in multipolar cells were reduced to one-half of control at higher concentrations of presynaptic BAPTA and EGTA (∼0.5 and ∼7 mm, respectively). Frequency-dependent facilitation of EPSPs in bitufted cells was abolished by EGTA at concentrations of > 0.2 mm, suggesting that accumulation of free Ca2+ is essential for facilitation in the terminals contacting bitufted cells. In contrast, facilitation was unaffected or even slightly increased in the terminals loaded with BAPTA in the concentration range 0.02–0.5 mm. This is attributed to partial saturation of exogenously added BAPTA. However, BAPTA at concentrations > 1 mm also abolished facilitation. Frequency-dependent depression of EPSPs in multipolar cells was not significantly reduced by EGTA. With BAPTA, the depression decreased at concentrations > 0.5 mm, concomitant with a reduction in amplitude of the first EPSP in a train. An analysis is presented that interprets the effects of EGTA and BAPTA on synaptic efficacy and its short-term modification during paired-pulse stimulation in terms of changes in [Ca2+] at the release site ([Ca2+]RS) and that infers the affinity of the Ca2+ sensor from the dependence of unitary EPSPs on [Ca2+]o. The results suggest that the target cell-specific difference in release from the terminals on bitufted or multipolar cells can be explained by a longer diffusional distance between Ca2+ channels and release sites and/or lower Ca2+ channels density in the terminals that contact bitufted cells. This would lead to a lower [Ca2+] at release sites and would also explain the higher apparent KD of the Ca2+ sensor in facilitating terminals. PMID:11251060

Promoting response variability and stimulus generalization in martial arts training.

PubMed Central

Harding, Jay W; Wacker, David P; Berg, Wendy K; Rick, Gary; Lee, John F

2004-01-01

The effects of reinforcement and extinction on response variability and stimulus generalization in the punching and kicking techniques of 2 martial arts students were evaluated across drill and sparring conditions. During both conditions, the students were asked to demonstrate different techniques in response to an instructor's punching attack. During baseline, the students received no feedback on their responses in either condition. During the intervention phase, the students received differential reinforcement in the form of instructor feedback for each different punching or kicking technique they performed during a session of the drill condition, but no reinforcement was provided for techniques in the sparring condition. Results showed that both students increased the number of different techniques they performed when reinforcement and extinction procedures were conducted during the drill condition, and that this increase in response variability generalized to the sparring condition. PMID:15293637

A kicking simulator to investigate the foot-ball interaction during a rugby place kick.

PubMed

Minnaar, Nick; van den Heever, Dawie J

2015-01-01

Foot-ball interaction is an important aspect in rugby place kicking but has received very little attention in literature. This preliminary study presents an adjustable mechanical kicking simulator used to investigate different foot positions and orientations during the foot-ball interaction on resultant ball motion. It was found that changes in foot position and orientation during ball contact can have a large influence on ball motion. It is believed that with further research an optimal place-kicking technique can be found to maximize energy transfer to the ball while still maintaining accuracy.

SYNCHROTRON RADIO FREQUENCY PHASE CONTROL SYSTEM

DOEpatents

Plotkin, M.; Raka, E.C.; Snyder, H.S.

1963-05-01

A system for canceling varying phase changes introduced by connecting cables and control equipment in an alternating gradient synchrotron is presented. In a specific synchrotron embodiment twelve spaced accelerating stations for the proton bunches are utilized. In order to ensure that the protons receive their boost or kick at the exact instant necessary it is necessary to compensate for phase changes occurring in the r-f circuitry over the wide range of frequencies dictated by the accelerated velocities of the proton bunches. A constant beat frequency is utilized to transfer the r-f control signals through the cables and control equipment to render the phase shift constant and readily compensable. (AEC)

An interval kicking progression for return to soccer following lower extremity injury.

PubMed

Arundale, Amelia; Silvers, Holly; Logerstedt, David; Rojas, Jaime; Snyder-Mackler, Lynn

2015-02-01

The majority of all soccer injuries affect the lower extremities. Regardless of whether the injured limb is an athlete's preferred kicking or stance leg, a lower extremity injury may affect their ability to impact the ball. Sport-specific biomechanical progressions to augment loading and gradually reintroduce a player to the demands of sport have been developed for upper extremity sports such as baseball, softball, tennis, and golf. Generalized return to soccer progressions have also been published in order to assist clinicians in safely returning athletes to sport; however, there are no specific progressions for the early stages of kicking designed to introduce stance leg loading and kicking leg impact. Thus, the purpose of this clinical commentary was to review the existing literature elucidating the biomechanics of kicking a soccer ball and propose a progressive kicking program to support clinicians in safely returning their soccer athletes to the demands of sport. The interval kicking program (IKP) describes clinical guidelines for readiness to begin a kicking program as well as possible readiness to return to sport measures. The program is performed on alternate days integrating therapeutic exercise and cardiovascular fitness. The IKP gradually introduces a player to the loading and impact of kicking. The progression increases kicking distance (using the markings of a soccer field as a guide), volume, and intensity and uses proposed soreness rules, effusion guidelines, and player feedback in order to assist clinicians in determining readiness for advancement though the stages. The IKP also recommends utility of specific tests and measures to determine readiness for return to sport. Gradual reintroduction to sport specific demands is essential for a safe return to soccer. This return to sport progression provides a framework integrating injury specific therapeutic exercise, cardiovascular fitness, and the return to kicking progression, to assist clinicians in initiating an athletes' return to soccer. Level 5.

Optimal Diabatic Dynamics of Majoarana-based Topological Qubits

NASA Astrophysics Data System (ADS)

Seradjeh, Babak; Rahmani, Armin; Franz, Marcel

In topological quantum computing, unitary operations on qubits are performed by adiabatic braiding of non-Abelian quasiparticles such as Majorana zero modes and are protected from local environmental perturbations. This scheme requires slow operations. By using the Pontryagin's maximum principle, here we show the same quantum gates can be implemented in much shorter times through optimal diabatic pulses. While our fast diabatic gates no not enjoy topological protection, they provide significant practical advantages due to their optimal speed and remarkable robustness to calibration errors and noise. NSERC, CIfAR, NSF DMR- 1350663, BSF 2014345.

The Momentum Kick Model Description of the Near-Side Ridge and Jet Quenching

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

Wong, Cheuk-Yin

2008-12-01

In the momentum kick model, a near-side jet parton occurs near the surface, kicks medium partons, loses energy, and fragments into the trigger particle and fragmentation products. The kicked medium partons subsequently materialize as the observed ridge particles which cary direct information on the magnitude of the momentum kick and the initial parton momentum distribution at the moment of jet-parton collision. The initial parton momentum distribution, extracted from the STAR ridge data for central Au-Au collisions at \\sqrt{s_NN} = 200 GeV, has a thermal-like transverse momentum distribution, but a non-Gaussian, relatively flat rapidity distribution at mid-rapidity with sharp kinematic boundariesmore » at large rapidities. The degree of jet quenching and the centrality dependence of the ridge yield can also be described by the momentum kick model.« less

Effect of fatigue on reaction time, response time, performance time, and kick impact in taekwondo roundhouse kick.

PubMed

Sant'Ana, Jader; Franchini, Emerson; da Silva, Vinicius; Diefenthaeler, Fernando

2017-06-01

Reaction time and response time are considered important abilities and can potentially affect combat performance. This study investigated the effect of a specific fatigue protocol on reaction time, response time, performance time, and kick impact. Seven male athletes reported to the laboratory on two different days. During day one, athletes performed a specific progressive taekwondo test, and on day two, a protocol for determining reaction time, response time, performance time, and kick impact before and after a time to exhaustion test at an intensity level corresponding to the maximal kick frequency obtained during the specific progressive taekwondo test. Muscle activation from rectus femoris and kick impact of the preferred limb were assessed. No differences were observed for response time and performance time. However, kick impact decreased (43 ± 27 to 13 ± 10 g, p < 0.01) while reaction time increased (145 ± 51 to 223 ± 133 ms, p < 0.05). Moderate correlation was observed between kick impact and response time (r = 0.565; p < 0.01), and kick impact and performance time (r = 0.494; p < 0.05). Results indicate that coaches and athletes may use taekwondo training programmes on coordination-based exercises leading to improve response time and to reduce fatigue effects in order to improve technique effectiveness and enhance the possibilities of scoring in a competitive situation.

The evolution of kicked stellar-mass black holes in star cluster environments

NASA Astrophysics Data System (ADS)

Webb, Jeremy J.; Leigh, Nathan W. C.; Singh, Abhishek; Ford, K. E. Saavik; McKernan, Barry; Bellovary, Jillian

2018-03-01

We consider how dynamical friction acts on black holes that receive a velocity kick while located at the centre of a gravitational potential, analogous to a star cluster, due to either a natal kick or the anisotropic emission of gravitational waves during a black hole-black hole merger. Our investigation specifically focuses on how well various Chandrasekhar-based dynamical friction models can predict the orbital decay of kicked black holes with mbh ≲ 100 M⊙ due to an inhomogeneous background stellar field. In general, the orbital evolution of a kicked black hole follows that of a damped oscillator where two-body encounters and dynamical friction serve as sources of damping. However, we find models for approximating the effects of dynamical friction do not accurately predict the amount of energy lost by the black hole if the initial kick velocity vk is greater than the stellar velocity dispersion σ. For all kick velocities, we also find that two-body encounters with nearby stars can cause the energy evolution of a kicked BH to stray significantly from standard dynamical friction theory as encounters can sometimes lead to an energy gain. For larger kick velocities, we find the orbital decay of a black hole departs from classical theory completely as the black hole's orbital amplitude decays linearly with time as opposed to exponentially. Therefore, we have developed a linear decay formalism, which scales linearly with black hole mass and v_k/σ in order to account for the variations in the local gravitational potential.

The acute effects of graded physiological strain on soccer kicking performance: a randomized, controlled cross-over study.

PubMed

Radman, Ivan; Wessner, Barbara; Bachl, Norbert; Ruzic, Lana; Hackl, Markus; Prpic, Tomislav; Markovic, Goran

2016-02-01

The aim of the present study was to examine the acute effects of graded physiological strain on soccer kicking performance. Twenty-eight semi-professional soccer players completed both experimental and control procedure. The experimental protocol incorporated repeated shooting trials combined with a progressive discontinuous maximal shuttle-run intervention. The initial running velocity was 8 km/h and increasing for 1 km/h every 3 min until exhaustion. The control protocol comprised only eight subsequent shooting trials. The soccer-specific kicking accuracy (KA; average distance from the ball-entry point to the goal center), kicking velocity (KV), and kicking quality (KQ; kicking accuracy divided by the time elapsed from hitting the ball to the point of entry) were evaluated via reproducible and valid test over five individually determined exercise intensity zones. Compared with baseline or exercise at intensities below the second lactate threshold (LT2), physiological exertion above the LT2 (blood lactate > 4 mmol/L) resulted in meaningful decrease in KA (11-13%; p < 0.05), KV (3-4%; p < 0.05), and overall KQ (13-15%; p < 0.01). The light and moderate-intensity exercise below the LT2 had no significant effect on soccer kicking performance. The results suggest that high-intensity physiological exertion above the player's LT2 impairs soccer kicking performance. In contrast, light to moderate physiological stress appears to be neither harmful nor beneficial for kicking performance.

A local chaotic quasi-attractor in a kicked rotator

NASA Astrophysics Data System (ADS)

Jiang, Yu-Mei; Lu, Yun-Qing; Zhao, Jin-Gang; Wang, Xu-Ming; Chen, He-Sheng; He, Da-Ren

2002-03-01

Recently, Hu et al. reported a diffusion in a special kind of stochastic web observed in a kicked rotator described by a discontinuous but invertible two-dimensional area-preserving map^1. We modified the function form of the system so that the period of the kicking force becomes different in two parts of the space, and the conservative map becomes both discontinuous and noninvertible. It is found that when the ratio between both periods becomes smaller or larger than (but near to) 1, the chaotic diffusion in the web transfers to chaotic transients, which are attracted to the elliptic islands those existed inside the holes of the web earlier when the ratio equals 1. As soon as reaching the islands, the iteration follows the conservative laws exactly. Therefore we address these elliptic islands as "regular quasi-attractor"^2. When the ratio increases further and becomes far from 1, all the elliptic islands disappear and a local chaotic quasi-attractor appears instead. It attracts the iterations starting from most initial points in the phase space. This behavior may be considered as a kind of "confinement" of chaotic motion of a particle. ^1B. Hu et al., Phys.Rev.Lett.,82(1999)4224. ^2J. Wang et al., Phys.Rev.E, 64(2001)026202.

A biomechanical analysis of common lunge tasks in badminton.

PubMed

Kuntze, Gregor; Mansfield, Neil; Sellers, William

2010-01-01

The lunge is regularly used in badminton and is recognized for the high physical demands it places on the lower limbs. Despite its common occurrence, little information is available on the biomechanics of lunging in the singles game. A video-based pilot study confirmed the relatively high frequency of lunging, approximately 15% of all movements, in competitive singles games. The biomechanics and performance characteristics of three badminton-specific lunge tasks (kick, step-in, and hop lunge) were investigated in the laboratory with nine experienced male badminton players. Ground reaction forces and kinematic data were collected and lower limb joint kinetics calculated using an inverse dynamics approach. The step-in lunge was characterized by significantly lower mean horizontal reaction force at drive-off and lower mean peak hip joint power than the kick lunge. The hop lunge resulted in significantly larger mean reaction forces during loading and drive-off phases, as well as significantly larger mean peak ankle joint moments and knee and ankle joint powers than the kick or step-in lunges. These findings indicate that, within the setting of this investigation, the step-in lunge may be beneficial for reducing the muscular demands of lunge recovery and that the hop lunge allows for higher positive power output, thereby presenting an efficient lunging method.

Kick the habit: a social marketing campaign by Aboriginal communities in NSW.

PubMed

Campbell, M A; Finlay, S; Lucas, K; Neal, N; Williams, R

2014-01-01

Tackling smoking is an integral component of efforts to improve health outcomes in Aboriginal communities. Social marketing is an effective strategy for promoting healthy attitudes and influencing behaviours; however, there is little evidence for its success in reducing smoking rates in Aboriginal communities. This paper outlines the development, implementation and evaluation of Kick the Habit Phase 2, an innovative tobacco control social marketing campaign in Aboriginal communities in New South Wales (NSW). The Aboriginal Health & Medical Research Council worked with three Aboriginal communities and a creative agency to develop locally tailored, culturally relevant social marketing campaigns. Each community determined the target audience and main messages, and identified appropriate local champions and marketing tools. Mixed methods were used to evaluate the campaign, including surveys and interviews with community members and Aboriginal Community Controlled Health Service staff. Community survey participants demonstrated high recall of smoking cessation messages, particularly for messages and images specific to the Kick the Habit campaign. Staff participating in interviews reported an increased level of interest from community members in smoking cessation programs, as well as increased confidence and skills in developing further social marketing campaigns. Aboriginal community-driven social marketing campaigns in tobacco control can build capacity, are culturally relevant and lead to high rates of recall in Aboriginal communities.

Time-optimal thermalization of single-mode Gaussian states

NASA Astrophysics Data System (ADS)

Carlini, Alberto; Mari, Andrea; Giovannetti, Vittorio

2014-11-01

We consider the problem of time-optimal control of a continuous bosonic quantum system subject to the action of a Markovian dissipation. In particular, we consider the case of a one-mode Gaussian quantum system prepared in an arbitrary initial state and which relaxes to the steady state due to the action of the dissipative channel. We assume that the unitary part of the dynamics is represented by Gaussian operations which preserve the Gaussian nature of the quantum state, i.e., arbitrary phase rotations, bounded squeezing, and unlimited displacements. In the ideal ansatz of unconstrained quantum control (i.e., when the unitary phase rotations, squeezing, and displacement of the mode can be performed instantaneously), we study how control can be optimized for speeding up the relaxation towards the fixed point of the dynamics and we analytically derive the optimal relaxation time. Our model has potential and interesting applications to the control of modes of electromagnetic radiation and of trapped levitated nanospheres.

ELM mitigation studies in JET and implications for ITER

NASA Astrophysics Data System (ADS)

de La Luna, Elena

2009-11-01

Type I edge localized modes (ELMs) remain a serious concern for ITER because of the high transient heat and particle flux that can lead to rapid erosion of the divertor plates. This has stimulated worldwide research on exploration of different methods to avoid or at least mitigate the ELM energy loss while maintaining adequate confinement. ITER will require reliable ELM control over a wide range of operating conditions, including changes in the edge safety factor, therefore a suite of different techniques is highly desirable. In JET several techniques have been demonstrated for control the frequency and size of type I ELMs, including resonant perturbations of the edge magnetic field (RMP), ELM magnetic triggering by fast vertical movement of the plasma column (``vertical kicks'') and ELM pacing using pellet injection. In this paper we present results from recent dedicated experiments in JET focusing on integrating the different ELM mitigation methods into similar plasma scenarios. Plasma parameter scans provide comparison of the performance of the different techniques in terms of both the reduction in ELM size and on the impact of each control method on plasma confinement. The compatibility of different ELM mitigation schemes has also been investigated. The plasma response to RMP and vertical kicks during the ELM mitigation phase shares common features: the reduction in ELM size (up to a factor of 3) is accompanied by a reduction in pedestal pressure (mainly due to a loss of density) with only minor (< 10%) reduction of the stored energy. Interestingly, it has been found that the combined application of RMP and kicks leads to a reduction of the threshold perturbation level (vertical displacement in the case of the kicks) necessary for the ELM mitigation to occur. The implication of these results for ITER will be discussed.

Kinematic effects of a short-term fatigue protocol on punt-kicking performance.

PubMed

Coventry, Evan; Ball, Kevin; Parrington, Lucy; Aughey, Robert; McKenna, Michael

2015-01-01

The punt kick is a fundamental skill used in several team sports; however, there has been a lack of research on how fatigue affects its technique. The purpose of this study was to determine the effects of short-term fatigue on punt-kicking performance. Eight elite and sub-elite Australian Football players performed maximal drop punt kicks on their preferred leg prior to, during and after a match-specific fatigue protocol. Optotrak Certus collected kinematic data from kick foot toe-off until ball contact. Repeated-measures analysis of variance showed a significant increase in 20 m sprint times after each short-term protocol, indicating fatigue. Foot speed did not significantly change with fatigue; however, increases in the range of motion at the pelvis and kicking thigh, along with increases in kicking thigh angular velocity, occurred. For the support leg, maximum knee flexion angular velocity increased while there was greater flexion found at the knee and hip, and greater range of motion at the knee. Players are able to make kinematic adaptations in order to maintain foot speed while punting for maximal distance after short-term efforts.

Spatial evolution of quantum mechanical states

NASA Astrophysics Data System (ADS)

Christensen, N. D.; Unger, J. E.; Pinto, S.; Su, Q.; Grobe, R.

2018-02-01

The time-dependent Schrödinger equation is solved traditionally as an initial-time value problem, where its solution is obtained by the action of the unitary time-evolution propagator on the quantum state that is known at all spatial locations but only at t = 0. We generalize this approach by examining the spatial evolution from a state that is, by contrast, known at all times t, but only at one specific location. The corresponding spatial-evolution propagator turns out to be pseudo-unitary. In contrast to the real energies that govern the usual (unitary) time evolution, the spatial evolution can therefore require complex phases associated with dynamically relevant solutions that grow exponentially. By introducing a generalized scalar product, for which the spatial generator is Hermitian, one can show that the temporal integral over the probability current density is spatially conserved, in full analogy to the usual norm of the state, which is temporally conserved. As an application of the spatial propagation formalism, we introduce a spatial backtracking technique that permits us to reconstruct any quantum information about an atom from the ionization data measured at a detector outside the interaction region.

Phase space information in a non-linear quantum system containing a Kerr-like medium through Su(1, 1)-algebraic treatment

NASA Astrophysics Data System (ADS)

Mohamed, Abdel-Baset A.

2018-05-01

Analytical description for a Su(2)-quantum system interacting with a damped Su(1, 1)-cavity, which is filled with a non-linear Kerr medium, is presented. The dynamics of non-classicality of Su(1, 1)-state is investigated via the negative part of the Wigner function. We show that the negative part depends on the unitary interaction and the Kerr-like medium and it can be disappeared by increasing the dissipation rate and the detuning parameter. The phase space information of the Husimi function and its Wehrl density is very sensitive not only to the coupling to the environment and the unitary interaction but also to the detuning as well as to the Kerr-like medium. The phase space information may be completely erased by increasing the coupling to the environment. The coherence loss of the Su(2)-state is investigated via the Husimi Wehrl entropy. If the effects of the detuning parameter or/and of the Kerr-like medium are combined with the damping effect, the damping effect of the coupling to the environment may be weaken, and the Wehrl entropy is delayed to reach its steady-state value. At the steady-state value, the phase space information and the coherence are quickly lost.

An intra-neural microstimulation system for ultra-high field magnetic resonance imaging and magnetoencephalography.

PubMed

Glover, Paul M; Watkins, Roger H; O'Neill, George C; Ackerley, Rochelle; Sanchez-Panchuelo, Rosa; McGlone, Francis; Brookes, Matthew J; Wessberg, Johan; Francis, Susan T

2017-10-01

Intra-neural microstimulation (INMS) is a technique that allows the precise delivery of low-current electrical pulses into human peripheral nerves. Single unit INMS can be used to stimulate individual afferent nerve fibres during microneurography. Combining this with neuroimaging allows the unique monitoring of central nervous system activation in response to unitary, controlled tactile input, with functional magnetic resonance imaging (fMRI) providing exquisite spatial localisation of brain activity and magnetoencephalography (MEG) high temporal resolution. INMS systems suitable for use within electrophysiology laboratories have been available for many years. We describe an INMS system specifically designed to provide compatibility with both ultra-high field (7T) fMRI and MEG. Numerous technical and safety issues are addressed. The system is fully analogue, allowing for arbitrary frequency and amplitude INMS stimulation. Unitary recordings obtained within both the MRI and MEG screened-room environments are comparable with those obtained in 'clean' electrophysiology recording environments. Single unit INMS (current <7μA, 200μs pulses) of individual mechanoreceptive afferents produces appropriate and robust responses during fMRI and MEG. This custom-built MRI- and MEG-compatible stimulator overcomes issues with existing INMS approaches; it allows well-controlled switching between recording and stimulus mode, prevents electrical shocks because of long cable lengths, permits unlimited patterns of stimulation, and provides a system with improved work-flow and participant comfort. We demonstrate that the requirements for an INMS-integrated system, which can be used with both fMRI and MEG imaging systems, have been fully met. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

Is the Link Between the Observed Velocities of Neutron Stars and their Progenitors a Simple Mass Relationship?

NASA Astrophysics Data System (ADS)

Bray, J. C.

2017-11-01

While the imparting of velocity `kicks' to compact remnants from supernovae is widely accepted, the relationship of the `kick' to the progenitor is not. We propose the `kick' is predominantly a result of conservation of momentum between the ejected and compact remnant masses. We propose the `kick' velocity is given by v kick = α(M ejecta/M remnant)+β, where α and β are constants we wish to determine. To test this we use the BPASS v2 (Binary Population and Spectral Synthesis) code to create stellar populations from both single star and binary star evolutionary pathways. We then use our Remnant Ejecta and Progenitor Explosion Relationship (REAPER) code to apply `kicks' to neutron stars from supernovae in these models using a grid of α and β values, (from 0 to 200 km s-1 in steps of 10 km s-1), in three different `kick' orientations, (isotropic, spin-axis aligned and orthogonal to spin-axis) and weighted by three different Salpeter initial mass functions (IMF's), with slopes of -2.0, -2.35 and -2.70. We compare our synthetic 2D and 3D velocity probability distributions to the distributions provided by Hobbs et al. (1995).

The Kπ Interaction in Finite Volume

NASA Astrophysics Data System (ADS)

Zhou, Dan; Cui, Er-Liang; Chen, Hua-Xing; Geng, Li-Sheng; Zhu, Li-Hua

We calculate energy levels of the Kπ scattering in the K∗ channel in finite volume using chiral unitary theory. We use these energy levels to obtain the Kπ phase shifts and the K∗ meson properties. We also investigate their dependence on the pion mass and compare this with Lattice QCD calculations.

Unitary Root Music and Unitary Music with Real-Valued Rank Revealing Triangular Factorization

DTIC Science & Technology

2010-06-01

AFRL-RY-WP-TP-2010-1213 UNITARY ROOT MUSIC AND UNITARY MUSIC WITH REAL-VALUED RANK REVEALING TRIANGULAR FACTORIZATION (Postprint) Nizar...DATES COVERED (From - To) June 2010 Journal Article Postprint 08 September 2006 – 31 August 2009 4. TITLE AND SUBTITLE UNITARY ROOT MUSIC AND...UNITARY MUSIC WITH REAL-VALUED RANK REVEALING TRIANGULAR FACTORIZATION (Postprint) 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA8650-05-D-1912-0007 5c

The relative kicking frequency of infants born full-term and preterm during learning and short-term and long-term memory periods of the mobile paradigm.

PubMed

Heathcock, Jill C; Bhat, Anjana N; Lobo, Michele A; Galloway, James C

2005-01-01

Infants born preterm differ in their spontaneous kicking, as well as their learning and memory abilities in the mobile paradigm, compared with infants born full-term. In the mobile paradigm, a supine infant's ankle is tethered to a mobile so that leg kicks cause a proportional amount of mobile movement. The purpose of this study was to investigate the relative kicking frequency of the tethered (right) and nontethered (left) legs in these 2 groups of infants. Ten infants born full-term and 10 infants born preterm (<33 weeks gestational age, <2,500 g) and 10 comparison infants participated in the study. The relative kicking frequencies of the tethered and nontethered legs were analyzed during learning and short-term and long-term memory periods of the mobile paradigm. Infants born full-term showed an increase in the relative kicking frequency of the tethered leg during the learning period and the short-term memory period but not for the long-term memory period. Infants born preterm did not show a change in kicking pattern for learning or memory periods, and consistently kicked both legs in relatively equal amounts. Infants born full-term adapted their baseline kicking frequencies in a task-specific manner to move the mobile and then retained this adaptation for the short-term memory period. In contrast, infants born preterm showed no adaptation, suggesting a lack of purposeful leg control. This lack of control may reflect a general decrease in the ability of infants born preterm to use their limb movements to interact with their environment. As such, the mobile paradigm may be clinically useful in the early assessment and intervention of infants born preterm and at risk for future impairment.

Classical and quantum dynamics of a kicked relativistic particle in a box

NASA Astrophysics Data System (ADS)

Yusupov, J. R.; Otajanov, D. M.; Eshniyazov, V. E.; Matrasulov, D. U.

2018-03-01

We study classical and quantum dynamics of a kicked relativistic particle confined in a one dimensional box. It is found that in classical case for chaotic motion the average kinetic energy grows in time, while for mixed regime the growth is suppressed. However, in case of regular motion energy fluctuates around certain value. Quantum dynamics is treated by solving the time-dependent Dirac equation with delta-kicking potential, whose exact solution is obtained for single kicking period. In quantum case, depending on the values of the kicking parameters, the average kinetic energy can be quasi periodic, or fluctuating around some value. Particle transport is studied by considering spatio-temporal evolution of the Gaussian wave packet and by analyzing the trembling motion.

Effect of stance position on kick performance in taekwondo.

PubMed

Estevan, Isaac; Jandacka, Daniel; Falco, Coral

2013-01-01

In taekwondo, the stance position can potentially affect kick performance. The aim of this study was to analyse mechanical variables in the roundhouse kick in taekwondo according to three stance positions (0°, 45°, 90°). Nine experienced taekwondo athletes performed consecutive kicking trials in a random order according to these three relative positions of the feet on the ground. Measurements for the mechanical analysis were performed using two 3D force plates and an eight-camera motion capture system. The taekwondo athletes' reaction and execution times were shorter when starting from the 0° and 45° stance positions than from the 90° position (P < 0.05). Moreover, the ground reaction force was negatively correlated with execution time and positively with velocity of thigh and shank. Our results suggest that the stance position affects the execution technique of taekwondo athletes' kicks. It is suggested that athletes should not adopt the 90° stance position because it will not enable them to achieve the best performance in the roundhouse kick.

a Study on Impact Analysis of Side Kick in Taekwondo

NASA Astrophysics Data System (ADS)

Lee, Jung-Hyun; Lee, Young-Shin; Han, Kyu-Hyun

Taekwondo is a martial art form and sport that uses the hands and feet for attack and defense. Taekwondo basic motion is composed of the breaking, competition and poomsea motions. The side kick is one of the most important breaking motions. The side kick with the front foot can be made in two steps. In the first step, the front foot is extended forward from the back stance free-fighting position. For the second step, the rear foot is followed simultaneously. Then, the side kick is executed while the entire body weight rests on the rear foot. In this paper, the impact analysis on a human model for kicking posture was carried out. The ADAMS/LifeMOD used numerical modeling and simulation for the side kick. The numerical human models for assailant and opponent in competition motion were developed. The maximum impact force on the human body was obtained by experiment and was applied to impact simulation. As a result, the impact displacement and velocity of the numerical human model were investigated.

Resonant pairing between fermions with unequal masses

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

Wu, Shin-Tza; Pao, C.-H.; Yip, S.-K.

We study via mean-field theory the pairing between fermions of different masses, especially at the unitary limit. At equal populations, the thermodynamic properties are identical with the equal mass case provided an appropriate rescaling is made. At unequal populations, for sufficiently light majority species, the system does not phase separate. For sufficiently heavy majority species, the phase separated normal phase have a density larger than that of the superfluid. For atoms in harmonic traps, the density profiles for unequal mass fermions can be drastically different from their equal-mass counterparts.

The Physics of Kicking a Football.

ERIC Educational Resources Information Center

Brancazio, Peter J.

1985-01-01

A physicist's view of the problems involved in kicking a football is described through the principles of projectile motion and aerodynamics. Sample equations, statistical summaries of kickoffs and punts, and calculation of launch parameters are presented along with discussion to clarify concepts of physics illustrated by kicking a football. (JN)

Explaining LIGO's observations via isolated binary evolution with natal kicks

NASA Astrophysics Data System (ADS)

Wysocki, Daniel; Gerosa, Davide; O'Shaughnessy, Richard; Belczynski, Krzysztof; Gladysz, Wojciech; Berti, Emanuele; Kesden, Michael; Holz, Daniel E.

2018-02-01

We compare binary evolution models with different assumptions about black-hole natal kicks to the first gravitational-wave observations performed by the LIGO detectors. Our comparisons attempt to reconcile merger rate, masses, spins, and spin-orbit misalignments of all current observations with state-of-the-art formation scenarios of binary black holes formed in isolation. We estimate that black holes (BHs) should receive natal kicks at birth of the order of σ ≃200 (50 ) km /s if tidal processes do (not) realign stellar spins. Our estimate is driven by two simple factors. The natal kick dispersion σ is bounded from above because large kicks disrupt too many binaries (reducing the merger rate below the observed value). Conversely, the natal kick distribution is bounded from below because modest kicks are needed to produce a range of spin-orbit misalignments. A distribution of misalignments increases our models' compatibility with LIGO's observations, if all BHs are likely to have natal spins. Unlike related work which adopts a concrete BH natal spin prescription, we explore a range of possible BH natal spin distributions. Within the context of our models, for all of the choices of σ used here and within the context of one simple fiducial parameterized spin distribution, observations favor low BH natal spin.

DEVELOPMENT AND EVALUATION OF A NOVEL TAEKWONDO CHEST PROTECTOR TO IMPROVE MOBILITY WHEN PERFORMING AXE KICKS

PubMed Central

Woo, J.H.; Ko, J.Y.; Choi, E.Y.; O'Sullivan, D.M.

2013-01-01

The axe kick, in Olympic style taekwondo, has been identified as the most popular scoring technique aimed to the head during full contact competition. The first purpose of this study was to identify and investigate design issues with the current World Taekwondo Federation approved chest protector. A secondary purpose was to develop a novel chest protector addressing the identified design issues and to conduct a biomechanical analysis. Fifteen male elite Taekwondo players were selected to perform three different styles of the axe kick, i.e., front, in-out, and out-in axe kick five times each for a total of 45 kicks. Two-way repeated measures ANOVA showed significant differences between the novel and existing chest protector conditions for vertical height of the toe, downward kicking foot speed, hip flexion angle and ipsilateral shoulder flexion extension range of motion (ROM) (p < 0.05). There were no significant differences between the control condition (no chest protector) and the novel chest protector condition for these variables (p > 0.05). These results indicate that the novel chest protector interferes less with both the lower and upper limbs during the performance of the axe kick and provides a more natural, free-moving alternative to the current equipment used. PMID:24744466

Quantum walks with an anisotropic coin II: scattering theory

NASA Astrophysics Data System (ADS)

Richard, S.; Suzuki, A.; de Aldecoa, R. Tiedra

2018-05-01

We perform the scattering analysis of the evolution operator of quantum walks with an anisotropic coin, and we prove a weak limit theorem for their asymptotic velocity. The quantum walks that we consider include one-defect models, two-phase quantum walks, and topological phase quantum walks as special cases. Our analysis is based on an abstract framework for the scattering theory of unitary operators in a two-Hilbert spaces setting, which is of independent interest.

Implementability of two-qubit unitary operations over the butterfly network and the ladder network with free classical communication

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

Akibue, Seiseki; Murao, Mio

2014-12-04

We investigate distributed implementation of two-qubit unitary operations over two primitive networks, the butterfly network and the ladder network, as a first step to apply network coding for quantum computation. By classifying two-qubit unitary operations in terms of the Kraus-Cirac number, the number of non-zero parameters describing the global part of two-qubit unitary operations, we analyze which class of two-qubit unitary operations is implementable over these networks with free classical communication. For the butterfly network, we show that two classes of two-qubit unitary operations, which contain all Clifford, controlled-unitary and matchgate operations, are implementable over the network. For the laddermore » network, we show that two-qubit unitary operations are implementable over the network if and only if their Kraus-Cirac number do not exceed the number of the bridges of the ladder.« less

Observing single quantum trajectories of a superconducting qubit: ensemble properties and driven dynamics

NASA Astrophysics Data System (ADS)

Weber, Steven; Murch, K. W.; Chantasri, A.; Dressel, J.; Jordan, A. N.; Siddiqi, I.

2014-03-01

We use weak measurements to track individual quantum trajectories of a superconducting qubit embedded in a microwave cavity. Using a near-quantum-limited parametric amplifier, we selectively measure either the phase or amplitude of the cavity field, and thereby confine trajectories to either the equator or a meridian of the Bloch sphere. We analyze ensembles of trajectories to determine statistical properties such as the most likely path and most likely time connecting pre and post-selected quantum states. We compare our results with theoretical predictions derived from an action principle for continuous quantum measurement. Furthermore, by introducing a qubit drive, we investigate the interplay between unitary state evolution and non-unitary measurement dynamics. This work was supported by the IARPA CSQ program and the ONR.

A Unitary ESPRIT Scheme of Joint Angle Estimation for MOTS MIMO Radar

PubMed Central

Wen, Chao; Shi, Guangming

2014-01-01

The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme. PMID:25106023

A unitary ESPRIT scheme of joint angle estimation for MOTS MIMO radar.

PubMed

Wen, Chao; Shi, Guangming

2014-08-07

The transmit array of multi-overlapped-transmit-subarray configured bistatic multiple-input multiple-output (MOTS MIMO) radar is partitioned into a number of overlapped subarrays, which is different from the traditional bistatic MIMO radar. In this paper, a new unitary ESPRIT scheme for joint estimation of the direction of departure (DOD) and the direction of arrival (DOA) for MOTS MIMO radar is proposed. In our method, each overlapped-transmit-subarray (OTS) with the identical effective aperture is regarded as a transmit element and the characteristics that the phase delays between the two OTSs is utilized. First, the measurements corresponding to all the OTSs are partitioned into two groups which have a rotational invariance relationship with each other. Then, the properties of centro-Hermitian matrices and real-valued rotational invariance factors are exploited to double the measurement samples and reduce computational complexity. Finally, the close-formed solution of automatically paired DOAs and DODs of targets is derived in a new manner. The proposed scheme provides increased estimation accuracy with the combination of inherent advantages of MOTS MIMO radar with unitary ESPRIT. Simulation results are presented to demonstrate the effectiveness and advantage of the proposed scheme.

Submillimeter-Wave Phasor Beam-Pattern Measurement Based on Two-Stage Heterodyne Mixing With Unitary Harmonic Difference

NASA Astrophysics Data System (ADS)

Hwang, Yuh-Jing; Rao, Ramprasad; Christensen, Rob; Chen, Ming-Tang; Chu, Tah-Hsiung

2007-06-01

A near-field phasor beam measurement system is developed for the characterization of heterodyne receiver optics at submillimeter-wave frequencies. The system synthesizes a pair of submillimeter-wave signals as the RF and local oscillator (LO) sources from common reference sources. The synthesized harmonic numbers of the RF and LO sources are arranged with difference by one, which makes this a new configuration with a unitary harmonic difference. The coherent RF and LO signal are down-converted by the receiver under test, then mixed with the microwave-frequency common reference signal to generate the second-order IF signal around 100 MHz for amplitude and phase comparison. The amplitude and phase fluctuation of the measurement system at 683 GHz is within +-0.2 dB and +-4deg in a 1-h period, respectively. The system dynamic range at 683 and 250 GHz can be as high as 43 and 47 dB, respectively. The system is then used to measure the receiver beam patterns at 683 and 250 GHz with different RF transmitting probe antennas.

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

Antipov, Sergey A.; Didenko, Alexander; Lebedev, Valeri

We present a design of a stripline kicker for Integrable Optics Test Accelerator (IOTA). For its experimental program IOTA needs two full-aperture kickers, capable to create an arbitrary controllable kick in 2D. For that reason their strengths are variable in a wide range of amplitudes up to 16 mrad, and the pulse length 100 ns is less than a revolution period for electrons. In addition, the kicker should have a physical aperture of 40 mm for a proposed operation with proton beam, and an outer size of 70 mm to fit inside existing quadrupole magnets to save space in themore » ring. Computer simulations using CST Microwave Studio show high field uniformity and wave impedance close to 50 {\\Omega}.« less

MEASURED TRANSVERSE COUPLING IMPEDANCE OF RHIC INJECTION AND ABORT KICKERS.

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

HAHN,H.; DAVINO,D.

2001-06-18

Concerns regarding possible transverse instabilities in RHIC and the SNS pointed to the need for measurements of the transverse coupling impedance of ring components. The impedance of the RHIC injection and abort kicker was measured using the conventional method based on the S{sub 21} forward transmission coefficient. A commercial 450 {Omega} twin-wire Lecher line were used and the data was interpreted via the log-formula. All measurements, were performed in test stands fully representing operational conditions including pulsed power supplies and connecting cables. The measured values for the transverse coupling impedance in kick direction and perpendicular to it are comparable inmore » magnitude, but differ from Handbook predictions.« less

Determining the best forecasting method to estimate unitary charges price indexes of PFI data in central region Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Ahmad Kamaruddin, Saadi Bin; Md Ghani, Nor Azura; Mohamed Ramli, Norazan

2013-04-01

The concept of Private Financial Initiative (PFI) has been implemented by many developed countries as an innovative way for the governments to improve future public service delivery and infrastructure procurement. However, the idea is just about to germinate in Malaysia and its success is still vague. The major phase that needs to be given main attention in this agenda is value for money whereby optimum efficiency and effectiveness of each expense is attained. Therefore, at the early stage of this study, estimating unitary charges or materials price indexes in each region in Malaysia was the key objective. This particular study aims to discover the best forecasting method to estimate unitary charges price indexes in construction industry by different regions in the central region of Peninsular Malaysia (Selangor, Federal Territory of Kuala Lumpur, Negeri Sembilan, and Melaka). The unitary charges indexes data used were from year 2002 to 2011 monthly data of different states in the central region Peninsular Malaysia, comprising price indexes of aggregate, sand, steel reinforcement, ready mix concrete, bricks and partition, roof material, floor and wall finishes, ceiling, plumbing materials, sanitary fittings, paint, glass, steel and metal sections, timber and plywood. At the end of the study, it was found that Backpropagation Neural Network with linear transfer function produced the most accurate and reliable results for estimating unitary charges price indexes in every states in central region Peninsular Malaysia based on the Root Mean Squared Errors, where the values for both estimation and evaluation sets were approximately zero and highly significant at p < 0.01. Therefore, artificial neural network is sufficient to forecast construction materials price indexes in Malaysia. The estimated price indexes of construction materials will contribute significantly to the value for money of PFI as well as towards Malaysian economical growth.

Inferences about Supernova Physics from Gravitational-Wave Measurements: GW151226 Spin Misalignment as an Indicator of Strong Black-Hole Natal Kicks

NASA Astrophysics Data System (ADS)

O'Shaughnessy, Richard; Gerosa, Davide; Wysocki, Daniel

2017-07-01

The inferred parameters of the binary black hole GW151226 are consistent with nonzero spin for the most massive black hole, misaligned from the binary's orbital angular momentum. If the black holes formed through isolated binary evolution from an initially aligned binary star, this misalignment would then arise from a natal kick imparted to the first-born black hole at its birth during stellar collapse. We use simple kinematic arguments to constrain the characteristic magnitude of this kick, and find that a natal kick vk≳50 km /s must be imparted to the black hole at birth to produce misalignments consistent with GW151226. Such large natal kicks exceed those adopted by default in most of the current supernova and binary evolution models.

Inferences about Supernova Physics from Gravitational-Wave Measurements: GW151226 Spin Misalignment as an Indicator of Strong Black-Hole Natal Kicks.

PubMed

O'Shaughnessy, Richard; Gerosa, Davide; Wysocki, Daniel

2017-07-07

The inferred parameters of the binary black hole GW151226 are consistent with nonzero spin for the most massive black hole, misaligned from the binary's orbital angular momentum. If the black holes formed through isolated binary evolution from an initially aligned binary star, this misalignment would then arise from a natal kick imparted to the first-born black hole at its birth during stellar collapse. We use simple kinematic arguments to constrain the characteristic magnitude of this kick, and find that a natal kick v_{k}≳50  km/s must be imparted to the black hole at birth to produce misalignments consistent with GW151226. Such large natal kicks exceed those adopted by default in most of the current supernova and binary evolution models.

Effect of olympic weight category on performance in the roundhouse kick to the head in taekwondo.

PubMed

Estevan, Isaac; Falco, Coral; Alvarez, Octavio; Molina-García, Javier

2012-03-01

In taekwondo, kick performance is generally measured using impact force and time. This study aimed to analyse performance in the roundhouse kick to the head according to execution distance between and within Olympic weight categories. The participants were 36 male athletes divided into three categories: featherweight (n = 10), welterweight (n = 15) and heavyweight (n = 11). Our results show that taekwondo athletes in all weight categories generate a similar relative impact force. However, the results indicate that weight has a large impact on kick performance, particularly in relation to total response time.

Effect of Olympic Weight Category on Performance in the Roundhouse Kick to the Head in Taekwondo

PubMed Central

Estevan, Isaac; Falco, Coral; Álvarez, Octavio; Molina-García, Javier

2012-01-01

In taekwondo, kick performance is generally measured using impact force and time. This study aimed to analyse performance in the roundhouse kick to the head according to execution distance between and within Olympic weight categories. The participants were 36 male athletes divided into three categories: featherweight (n = 10), welterweight (n = 15) and heavyweight (n = 11). Our results show that taekwondo athletes in all weight categories generate a similar relative impact force. However, the results indicate that weight has a large impact on kick performance, particularly in relation to total response time. PMID:23486074

A field simulation study of the effectiveness of penalty kick strategies in soccer: late alterations of kick direction increase errors and reduce accuracy.

PubMed

van der Kamp, John

2006-05-01

This field experiment investigated the relative merits of approaching the penalty kick with either a keeper-independent or keeper-dependent strategy. In the keeper-independent strategy, the shooter selects a target location in advance and disregards the goalkeeper's actions during the run-up. In the keeper-dependent strategy, the shooter makes a decision resting on the anticipation of the goalkeeper's movements during the run-up. Ten intermediate-level soccer players shot at one of two visually specified targets to the right and left side of the goal. In the keeper-independent strategy condition, participants were told that the visually specified target would not change. In the keeper-dependent strategy condition, participants were told that in half of the trials the visually specified target would change side at different times before ball contact, indicating that the direction of the kick needed to be altered. The results showed that penalty-taking performance was apt to be less than perfect in the keeper-dependent strategy condition. A decrease in the time available to alter kick direction resulted in a higher risk of not only an incorrect but also inaccurate shot placement. It is concluded that anticipating the goalkeeper's movements may degrade penalty kick performance, mainly due to insufficient time to modify the kicking action.

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

ERIC Educational Resources Information Center

Southard, Dan L.

2014-01-01

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

Differences in Soccer Kick Kinematics between Blind Players and Controls

ERIC Educational Resources Information Center

Giagazoglou, Paraskevi; Katis, Athanasios; Kellis, Eleftherios; Natsikas, Christos

2011-01-01

The purpose of the current study was to examine the kinematic differences during instep soccer kicks between players who were blind and sighted controls. Eleven male soccer players who were blind and nine male sighted performed instep kicks under static and dynamic conditions. The results indicated significantly higher (p less than 0.05) ball…

Universal quantum computation with temporal-mode bilayer square lattices

NASA Astrophysics Data System (ADS)

Alexander, Rafael N.; Yokoyama, Shota; Furusawa, Akira; Menicucci, Nicolas C.

2018-03-01

We propose an experimental design for universal continuous-variable quantum computation that incorporates recent innovations in linear-optics-based continuous-variable cluster state generation and cubic-phase gate teleportation. The first ingredient is a protocol for generating the bilayer-square-lattice cluster state (a universal resource state) with temporal modes of light. With this state, measurement-based implementation of Gaussian unitary gates requires only homodyne detection. Second, we describe a measurement device that implements an adaptive cubic-phase gate, up to a random phase-space displacement. It requires a two-step sequence of homodyne measurements and consumes a (non-Gaussian) cubic-phase state.

Anatomy of the Binary Black Hole Recoil: A Multipolar Analysis

NASA Technical Reports Server (NTRS)

Schnittman, Jeremy; Buonanno, Alessandra; vanMeter, James R.; Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.

2007-01-01

We present a multipolar analysis of the recoil velocity computed in recent numerical simulations of binary black hole coalescence, for both unequal masses and non-zero, non-precessing spins. We show that multipole moments up to and including 1 = 4 are sufficient to accurately reproduce the final recoil velocity (= 98%) and that only a few dominant modes contribute significantly to it (2 95%). We describe how the relative amplitude, and more importantly, the relative phase, of these few modes control the way in which the recoil builds up throughout the inspiral, merger, and ring-down phases. We also find that the numerical results can be reproduced, to a high level of accuracy, by an effective Newtonian formula for the multipole moments obtained by replacing in the Newtonian formula the radial separation with an effective radius computed from the numerical data. Beyond the merger, the numerical results are reproduced by a superposition of three Kerr quasi-normal modes. Analytic formulae, obtained by expressing the multipole moments in terms of the fundamental QNMs of a Kerr BH, are able to explain the onset and amount of '.anti-kick" for each of the simulations. Lastly, we apply this multipolar analysis to understand the remarkable difference between the amplitudes of planar and non-planar kicks for equal-mass spinning black holes.

Drop punt kicking induces eccentric knee flexor weakness associated with reductions in hamstring electromyographic activity.

PubMed

Duhig, Steven J; Williams, Morgan D; Minett, Geoffrey M; Opar, David; Shield, Anthony J

2017-06-01

To examine the effect of 100 drop punt kicks on isokinetic knee flexor strength and surface electromyographic activity of bicep femoris and medial hamstrings. Randomized control study. Thirty-six recreational footballers were randomly assigned to kicking or control groups. Dynamometry was conducted immediately before and after the kicking or 10min of sitting (control). Eccentric strength declined more in the kicking than the control group (p<0.001; d=1.60), with greater reductions in eccentric than concentric strength after kicking (p=0.001; d=0.92). No significant between group differences in concentric strength change were observed (p=0.089; d=0.60). The decline in normalized eccentric hamstring surface electromyographic activity (bicep femoris and medial hamstrings combined) was greater in the kicking than the control group (p<0.001; d=1.78), while changes in concentric hamstring surface electromyographic activity did not differ between groups (p=0.863; d=0.04). Post-kicking reductions in surface electromyographic activity were greater in eccentric than concentric actions for both bicep femoris (p=0.008; d=0.77) and medial hamstrings (p<0.001; d=1.11). In contrast, the control group exhibited smaller reductions in eccentric than concentric hamstring surface electromyographic activity for bicep femoris (p=0.026; d=0.64) and medial hamstrings (p=0.032; d=0.53). Reductions in bicep femoris surface electromyographic activity were correlated with eccentric strength decline (R=0.645; p=0.007). Reductions in knee flexor strength and hamstring surface electromyographic activity are largely limited to eccentric contractions and this should be considered when planning training loads in Australian Football. Copyright © 2016 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

PHASE DIFFERENTIAL INDICATING CIRCUIT

DOEpatents

Kirsten, F.A.

1962-01-01

An electronic circuit for totalizing the net phase difference between two alternating current signals is designed which responds to both increasing and decreasing phase changes. A phase comparator provldes an output pulse for each 360 deg of phase difference occurring, there being a negative pulse for phase shtft in one direction and a positive pulse for a phase shift in the opposite direction. A counting circuit utilizing glow discharge tubes receives the negative and positive pulses at a single input terminal and provides a running net total, pulses of one polarity dded and pulses of the opposite polarity being subtracted. The glow discharge tubes may be decaded to increase the total count capacity. (AEC)

Replica Resummation of the Baker-Campbell-Hausdorff Series

NASA Astrophysics Data System (ADS)

Vajna, Szabolcs; Klobas, Katja; Prosen, Tomaž; Polkovnikov, Anatoli

2018-05-01

We developed a novel perturbative expansion based on the replica trick for the Floquet Hamiltonian governing the dynamics of periodically kicked systems where the kick strength is the small parameter. The expansion is formally equivalent to an infinite resummation of the Baker-Campbell-Hausdorff series in the undriven (nonperturbed) Hamiltonian, while considering terms up to a finite order in the kick strength. As an application of the replica expansion, we analyze an Ising spin 1 /2 chain periodically kicked with a magnetic field with a strength h , which has both longitudinal and transverse components. We demonstrate that even away from the regime of high frequency driving, if there is heating, its rate is nonperturbative in the kick strength, bounded from above by a stretched exponential: e-const h-1 /2 . This guarantees the existence of a very long prethermal regime, where the dynamics is governed by the Floquet Hamiltonian obtained from the replica expansion.

Formation of Low-Mass X-Ray Binaries. II. Common Envelope Evolution of Primordial Binaries with Extreme Mass Ratios

NASA Astrophysics Data System (ADS)

Kalogera, Vassiliki; Webbink, Ronald F.

1998-01-01

We study the formation of low-mass X-ray binaries (LMXBs) through helium star supernovae in binary systems that have each emerged from a common envelope phase. LMXB progenitors must satisfy a large number of evolutionary and structural constraints, including survival through common envelope evolution, through the post-common envelope phase, where the precursor of the neutron star becomes a Wolf-Rayet star, and survival through the supernova event. Furthermore, the binaries that survive the explosion must reach interaction within a Hubble time and must satisfy stability criteria for mass transfer. These constraints, imposed under the assumption of a symmetric supernova explosion, prohibit the formation of short-period LMXBs transferring mass at sub-Eddington rates through any channel in which the intermediate progenitor of the neutron star is not completely degenerate. Barring accretion-induced collapse, the existence of such systems therefore requires that natal kicks be imparted to neutron stars. We use an analytical method to synthesize the distribution of nascent LMXBs over donor masses and orbital periods and evaluate their birthrate and systemic velocity dispersion. Within the limitations imposed by observational incompleteness and selection effects, and our neglect of secular evolution in the LMXB state, we compare our results with observations. However, our principal objective is to evaluate how basic model parameters (common envelope ejection efficiency, rms kick velocity, primordial mass ratio distribution) influence these results. We conclude that the characteristics of newborn LMXBs are primarily determined by age and stability constraints and the efficiency of magnetic braking and are largely independent of the primordial binary population and the evolutionary history of LMXB progenitors (except for extreme values of the average kick magnitude or of the common envelope ejection efficiency). Theoretical estimates of total LMXB birthrates are not credible, since they strongly depend on the observationally indeterminate frequency of primordial binaries with extreme mass ratios in long-period orbits.

Creating Rydberg electron wave packets using terahertz pulses

NASA Astrophysics Data System (ADS)

Bromage, Jake

1999-10-01

In this thesis I present experiments in which we excited classical-limit states of an atom using terahertz pulses. In a classical-limit state, an atom's outer electron is confined to a wave packet that orbits the core along a classical trajectory. Researchers have excited states with classical traits, but wave packets localized in all three dimensions have proved elusive. Theoretical studies have shown such states can be created using terahertz pulses. Using these techniques, we created a linear-orbit wave packet (LOWP), that is three-dimensionally localized and orbits along a line on one side of the atom's core. Terahertz pulses are sub-picosecond bursts of far- infrared radiation. Unlike ultrashort optical pulses, the electric field of terahertz pulses barely completes a single cycle. Our simulations of the atom-pulse interaction show that this electric field profile is critical in determining the quality of the wave packet. To characterize our terahertz pulses, we invented dithered-edge sampling which time- resolves the electric field using a photoconductive receiver and a triggered attenuator. We also studied how pulses are distorted after propagating through metallic structures, and used our findings to design our atomic experiments. We excited wave packets in atomic sodium using a two-step process. First, we used tunable, nanosecond dye lasers to excite an extreme Stark state. Next, we used a terahertz pump pulse to coherently redistribute population among extreme Stark states in neighboring manifolds. Interference between the final states produces a localized, dynamic LOWP. To analyze the LOWP, we ionized it with a stronger terahertz probe pulse, varying the pump-probe delay to map out its motion. We observed two strong LOWP signatures. Changing the static electric field produced small changes (2%) in the orbital period that agreed with our theoretical predictions. Secondly, because the LOWP scatters off the core, the pump-probe signal depended on the direction of the kick the LOWP received from the robe pulse. These observations, combined with our detailed simulations that used sodium parameters and the actual shape of the terahertz pulse, lead us to conclude that we excited a LOWP.

SNMR pulse sequence phase cycling

DOEpatents

Walsh, David O; Grunewald, Elliot D

2013-11-12

Technologies applicable to SNMR pulse sequence phase cycling are disclosed, including SNMR acquisition apparatus and methods, SNMR processing apparatus and methods, and combinations thereof. SNMR acquisition may include transmitting two or more SNMR pulse sequences and applying a phase shift to a pulse in at least one of the pulse sequences, according to any of a variety cycling techniques. SNMR processing may include combining SNMR from a plurality of pulse sequences comprising pulses of different phases, so that desired signals are preserved and indesired signals are canceled.

Cross-Phase Modulation: A New Technique for Controlling the Spectral, Temporal, and Spatial Properties of Ultrashort Pulses

NASA Astrophysics Data System (ADS)

Baldeck, P. L.; Ho, P. P.; Alfano, Robert R.

Self-phase modulation (SPM) is the principal mechanism responsible for the generation of picosecond and femtosecond white-light supercontinua. When an intense ultrashort pulse progagates through a medium, it distorts the atomic configuration of the material, which changes the refractive index. The pulse phase is time modulated, which causes the generation of new frequencies. This phase modulation originates from the pulse itself (self-phase modulation). It can also be generated by a copropagating pulse (cross-phase modulation).

Quantum localization for a kicked rotor with accelerator mode islands.

PubMed

Iomin, A; Fishman, S; Zaslavsky, G M

2002-03-01

Dynamical localization of classical superdiffusion for the quantum kicked rotor is studied in the semiclassical limit. Both classical and quantum dynamics of the system become more complicated under the conditions of mixed phase space with accelerator mode islands. Recently, long time quantum flights due to the accelerator mode islands have been found. By exploration of their dynamics, it is shown here that the classical-quantum duality of the flights leads to their localization. The classical mechanism of superdiffusion is due to accelerator mode dynamics, while quantum tunneling suppresses the superdiffusion and leads to localization of the wave function. Coupling of the regular type dynamics inside the accelerator mode island structures to dynamics in the chaotic sea proves increasing the localization length. A numerical procedure and an analytical method are developed to obtain an estimate of the localization length which, as it is shown, has exponentially large scaling with the dimensionless Planck's constant (tilde)h<1 in the semiclassical limit. Conditions for the validity of the developed method are specified.

Kick Stick Hands-on Challenge: Discover Circuits with PBS's "Design Squad Nation"[TM

ERIC Educational Resources Information Center

Feinberg, Lauren

2011-01-01

This article describes the "Kick Stick" activity from Design Squad Nation, in which kids turn a wooden paint stirrer and circuit into a motorized, spinning arm--then use it to kick a Ping-Pong[R] ball across the floor. Teachers can enrich their students' exploration of circuits and emphasize the engineering design process with "Design Squad…

Nonexponential Decoherence and Subdiffusion in Atom-Optics Kicked Rotor.

PubMed

Sarkar, Sumit; Paul, Sanku; Vishwakarma, Chetan; Kumar, Sunil; Verma, Gunjan; Sainath, M; Rapol, Umakant D; Santhanam, M S

2017-04-28

Quantum systems lose coherence upon interaction with the environment and tend towards classical states. Quantum coherence is known to exponentially decay in time so that macroscopic quantum superpositions are generally unsustainable. In this work, slower than exponential decay of coherences is experimentally realized in an atom-optics kicked rotor system subjected to nonstationary Lévy noise in the applied kick sequence. The slower coherence decay manifests in the form of quantum subdiffusion that can be controlled through the Lévy exponent. The experimental results are in good agreement with the analytical estimates and numerical simulations for the mean energy growth and momentum profiles of an atom-optics kicked rotor.

Averaged kick maps: less noise, more signal…and probably less bias

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

Pražnikar, Jure; Afonine, Pavel V.; Gunčar, Gregor

2009-09-01

Averaged kick maps are the sum of a series of individual kick maps, where each map is calculated from atomic coordinates modified by random shifts. These maps offer the possibility of an improved and less model-biased map interpretation. Use of reliable density maps is crucial for rapid and successful crystal structure determination. Here, the averaged kick (AK) map approach is investigated, its application is generalized and it is compared with other map-calculation methods. AK maps are the sum of a series of kick maps, where each kick map is calculated from atomic coordinates modified by random shifts. As such, theymore » are a numerical analogue of maximum-likelihood maps. AK maps can be unweighted or maximum-likelihood (σ{sub A}) weighted. Analysis shows that they are comparable and correspond better to the final model than σ{sub A} and simulated-annealing maps. The AK maps were challenged by a difficult structure-validation case, in which they were able to clarify the problematic region in the density without the need for model rebuilding. The conclusion is that AK maps can be useful throughout the entire progress of crystal structure determination, offering the possibility of improved map interpretation.« less

Swimming Speed of The Breaststroke Kick

PubMed Central

Strzała, Marek; Krężałek, Piotr; Kaca, Marcin; Głąb, Grzegorz; Ostrowski, Andrzej; Stanula, Arkadiusz; Tyka, Aleksander

2012-01-01

The breaststroke kick is responsible for a considerable portion of the forward propulsion in breaststroke swimming. The aim of this study was to measure selected anthropometric variables and functional properties of a swimmer’s body: length of body parts; functional range of motion in the leg joints and anaerobic power of the lower limbs. Chosen kinematic variables useful in the evaluation of swimming performance in the breaststroke kick were evaluated. In the present research, swimming speed using breaststroke kicks depended to the largest extent on anaerobic endurance (0.46, p < 0.05 partial correlations with age control). In addition, knee external rotation and swimming technique index had an impact on swimming speed and kick length (both partial correlations with age control 0.35, p < 0.08). A kinematic analysis of the breaststroke kick hip displacement compatible with horizontal body displacement was significantly negatively correlated with foot slip in the water opposite to body displacement (partial correlations: with leg length control −0.43, p < 0.05; with shank length control −0.45, p < 0.05, respectively). Present research and measurements of selected body properties, physical endurance and kinematic movement analysis may help in making a precise determination of an athlete’s talent for breaststroke swimming. PMID:23486737

Effects of Resonant and Random Excitations on the Proton Beam in the Large Hadron Collider, with Applications to the Design of Pulsed Hollow Electron Lenses for Active Halo Control

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

Fitterer, Miriam; Stancari, Giulio; Valishev, Alexander

We present the results of numerical simulations and experimental studies about the effects of resonant and random excitations on proton losses, emittances, and beam distributions in the Large Hadron Collider (LHC). In addition to shedding light on complex nonlinear effects, these studies are applied to the design of hollow electron lenses (HEL) for active beam halo control. In the High-Luminosity Large Hadron Collider (HL-LHC), a considerable amount of energy will be stored in the beam tails. To control and clean the beam halo, the installation of two hollow electron lenses, one per beam, is being considered. In standard electron-lens operation,more » a proton bunch sees the same electron current at every revolution. Pulsed electron beam operation (i.e., different currents for different turns) is also considered, because it can widen the range of achievable halo removal rates. For an axially symmetric electron beam, only protons in the halo are excited. If a residual field is present at the location of the beam core, these particles are exposed to time-dependent transverse kicks and to noise. We discuss the numerical simulations and the experiments conducted in 2016 and 2017 at injection energy in the LHC. The excitation patterns were generated by the transverse feedback and damping system, which acted as a flexible source of dipole kicks. Proton beam losses, emittances, and transverse distributions were recorded as a function of excitation patterns and strengths. The resonant excitations induced rich dynamical effects and nontrivial changes of the beam distributions, which, to our knowledge, have not previously been observed and studied in this detail. We conclude with a discussion of the tolerable and achievable residual fields and proposals for further studies.« less

Symmetry breaking in tensor models

NASA Astrophysics Data System (ADS)

Benedetti, Dario; Gurau, Razvan

2015-11-01

In this paper we analyze a quartic tensor model with one interaction for a tensor of arbitrary rank. This model has a critical point where a continuous limit of infinitely refined random geometries is reached. We show that the critical point corresponds to a phase transition in the tensor model associated to a breaking of the unitary symmetry. We analyze the model in the two phases and prove that, in a double scaling limit, the symmetric phase corresponds to a theory of infinitely refined random surfaces, while the broken phase corresponds to a theory of infinitely refined random nodal surfaces. At leading order in the double scaling limit planar surfaces dominate in the symmetric phase, and planar nodal surfaces dominate in the broken phase.

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

Livine, Etera R.

We introduce the set of framed (convex) polyhedra with N faces as the symplectic quotient C{sup 2N}//SU(2). A framed polyhedron is then parametrized by N spinors living in C{sup 2} satisfying suitable closure constraints and defines a usual convex polyhedron plus extra U(1) phases attached to each face. We show that there is a natural action of the unitary group U(N) on this phase space, which changes the shape of faces and allows to map any (framed) polyhedron onto any other with the same total (boundary) area. This identifies the space of framed polyhedra to the Grassmannian space U(N)/ (SU(2)×U(N−2)).more » We show how to write averages of geometrical observables (polynomials in the faces' area and the angles between them) over the ensemble of polyhedra (distributed uniformly with respect to the Haar measure on U(N)) as polynomial integrals over the unitary group and we provide a few methods to compute these integrals systematically. We also use the Itzykson-Zuber formula from matrix models as the generating function for these averages and correlations. In the quantum case, a canonical quantization of the framed polyhedron phase space leads to the Hilbert space of SU(2) intertwiners (or, in other words, SU(2)-invariant states in tensor products of irreducible representations). The total boundary area as well as the individual face areas are quantized as half-integers (spins), and the Hilbert spaces for fixed total area form irreducible representations of U(N). We define semi-classical coherent intertwiner states peaked on classical framed polyhedra and transforming consistently under U(N) transformations. And we show how the U(N) character formula for unitary transformations is to be considered as an extension of the Itzykson-Zuber to the quantum level and generates the traces of all polynomial observables over the Hilbert space of intertwiners. We finally apply the same formalism to two dimensions and show that classical (convex) polygons can be described in a similar fashion trading the unitary group for the orthogonal group. We conclude with a discussion of the possible (deformation) dynamics that one can define on the space of polygons or polyhedra. This work is a priori useful in the context of discrete geometry but it should hopefully also be relevant to (loop) quantum gravity in 2+1 and 3+1 dimensions when the quantum geometry is defined in terms of gluing of (quantized) polygons and polyhedra.« less

Comparing Neutron Star Kicks to Supernova Remnant Asymmetries

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

Holland-Ashford, Tyler; Lopez, Laura A.; Auchettl, Katie

2017-07-20

Supernova explosions are inherently asymmetric and can accelerate new-born neutron stars (NSs) to hundreds of km s{sup −1}. Two prevailing theories to explain NS kicks are ejecta asymmetries (e.g., conservation of momentum between NS and ejecta) and anisotropic neutrino emission. Observations of supernova remnants (SNRs) can give us insights into the mechanism that generates these NS kicks. In this paper, we investigate the relationship between NS kick velocities and the X-ray morphologies of 18 SNRs observed with the Chandra X-ray Observatory and the Röntgen Satellite ( ROSAT ). We measure SNR asymmetries using the power-ratio method (a multipole expansion technique),more » focusing on the dipole, quadrupole, and octupole power ratios. Our results show no correlation between the magnitude of the power ratios and NS kick velocities, but we find that for Cas A and G292.0+1.8, whose emission traces the ejecta distribution, their NSs are preferentially moving opposite to the bulk of the X-ray emission. In addition, we find a similar result for PKS 1209–51, CTB 109, and Puppis A; however, their emission is dominated by circumstellar/interstellar material, so their asymmetries may not reflect their ejecta distributions. Our results are consistent with the theory that NS kicks are a consequence of ejecta asymmetries as opposed to anisotropic neutrino emission. In the future, additional observations to measure NS proper motions within ejecta-dominated SNRs are necessary to robustly constrain the NS kick mechanism.« less

Comparison of Lower Limb Segments Kinematics in a Taekwondo Kick. An Approach to the Proximal to Distal Motion

PubMed Central

Estevan, Isaac; Falco, Coral; Silvernail, Julia Freedman; Jandacka, Daniel

2015-01-01

In taekwondo, there is a lack of consensus about how the kick sequence occurs. The aim of this study was to analyse the peak velocity (resultant and value in each plane) of lower limb segments (thigh, shank and foot), and the time to reach this peak velocity in the kicking lower limb during the execution of the roundhouse kick technique. Ten experienced taekwondo athletes (five males and five females; mean age of 25.3 ±5.1 years; mean experience of 12.9 ±5.3 years) participated voluntarily in this study performing consecutive kicking trials to a target located at their sternum height. Measurements for the kinematic analysis were performed using two 3D force plates and an eight camera motion capture system. The results showed that the proximal segment reached a lower peak velocity (resultant and in each plane) than distal segments (except the peak velocity in the frontal plane where the thigh and shank presented similar values), with the distal segment taking the longest to reach this peak velocity (p < 0.01). Also, at the instant every segment reached the peak velocity, the velocity of the distal segment was higher than the proximal one (p < 0.01). It provides evidence about the sequential movement of the kicking lower limb segments. In conclusion, during the roundhouse kick in taekwondo inter-segment motion seems to be based on a proximo-distal pattern. PMID:26557189

Comparison of Lower Limb Segments Kinematics in a Taekwondo Kick. An Approach to the Proximal to Distal Motion.

PubMed

Estevan, Isaac; Falco, Coral; Silvernail, Julia Freedman; Jandacka, Daniel

2015-09-29

In taekwondo, there is a lack of consensus about how the kick sequence occurs. The aim of this study was to analyse the peak velocity (resultant and value in each plane) of lower limb segments (thigh, shank and foot), and the time to reach this peak velocity in the kicking lower limb during the execution of the roundhouse kick technique. Ten experienced taekwondo athletes (five males and five females; mean age of 25.3 ±5.1 years; mean experience of 12.9 ±5.3 years) participated voluntarily in this study performing consecutive kicking trials to a target located at their sternum height. Measurements for the kinematic analysis were performed using two 3D force plates and an eight camera motion capture system. The results showed that the proximal segment reached a lower peak velocity (resultant and in each plane) than distal segments (except the peak velocity in the frontal plane where the thigh and shank presented similar values), with the distal segment taking the longest to reach this peak velocity (p < 0.01). Also, at the instant every segment reached the peak velocity, the velocity of the distal segment was higher than the proximal one (p < 0.01). It provides evidence about the sequential movement of the kicking lower limb segments. In conclusion, during the roundhouse kick in taekwondo inter-segment motion seems to be based on a proximo-distal pattern.

Effects of Olympic-style taekwondo kicks on an instrumented head-form and resultant injury measures.

PubMed

Fife, Gabriel P; O'Sullivan, David M; Pieter, Willy; Cook, David P; Kaminski, Thomas W

2013-12-01

The objective of this study was to assess the effect of taekwondo kicks and peak foot velocity (FVEL) on resultant head linear acceleration (RLA), head injury criterion (HIC15) and head velocity (HVEL). Each subject (n=12) randomly performed five repetitions of the turning kick (TK), clench axe kick (CA), front leg axe kick, jump back kick (JB) and jump spinning hook kick (JH) at the average standing head height for competitors in their weight division. A Hybrid II Crash Test Dummy head was fitted with a protective taekwondo helmet and instrumented with a triaxial accelerometer and fixed to a height-adjustable frame. Resultant head linear acceleration, HVEL, FVEL data were captured and processed using Qualysis Track Manager. The TK (130.11 ± 51.67 g) produced a higher RLA than the CA (54.95 ± 20.08 g, p<0.001, d=1.84) and a higher HIC15 than the JH (672.74 ± 540.89 vs 300.19 ± 144.35, p<0.001, ES=0.97). There was no difference in HVEL of the TK (4.73 ± 1.67 m/s) and that of the JB (4.43 ± 0.78 m/s; p=0.977, ES<0.01). The TK is of concern because it is the most common technique and cause of concussion in taekwondo. Future studies should aim to understand rotational accelerations of the head.

Difference in kick motion of adolescent soccer players in presence and absence of low back pain.

PubMed

Tojima, Michio; Torii, Suguru

2018-01-01

Many adolescent soccer players experience low back pain (LBP). However, there are no reports studying the kick motion of adolescent soccer players experiencing LBP. This study aimed to clarify the kick motion of adolescent soccer players in the presence and absence of LBP. We recruited 42 adolescent soccer players and divided them into two groups according to the presence of LBP (LBP group, n=22) and absence of LBP (NBP group, n=20). We measured real-time kick motion using a three-dimensional motion analysis system. We placed 65 spherical markers on each anatomical landmark and calculated the angle of the lumbar spine, center of mass (COM) of the whole body, and displacement of the support foot. We used an unpaired t-test to compare the data between the groups. Compared with the NBP group, the LBP group showed a lateral shift in COM, which increased the duration of kick motion. The presence of LBP affected the posterior positioning of the support foot and restricted the player's lumbar spine from bending laterally. A lateral shift in COM and larger rotation of the lumbar spine could stress the lumbar spine during kick motion. Therefore, coaches and athletic trainers should pay attention to soccer players' lumbar spine rotation and the COM shift during kick motion. This would be important for preventing LBP in adolescent soccer players. Copyright © 2017 Elsevier B.V. All rights reserved.

Isolated Attosecond Pulse Generation without the Need to Stabilize the Carrier-Envelope Phase of Driving Lasers

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

Gilbertson, Steve; Khan, Sabih D.; Wu Yi

2010-08-27

Single isolated attosecond pulses can be extracted from a pulse train with an ultrafast gate in the generation target. By setting the gate width sufficiently narrow with the generalized double optical gating, we demonstrate that single isolated attosecond pulses can be generated with any arbitrary carrier-envelope phase value of the driving laser. The carrier-envelope phase only affects the photon flux, not the pulse duration or contrast. Our results show that isolated attosecond pulses can be generated using carrier-envelope phase unstabilized 23 fs pulses directly from chirped pulse amplifiers.

A mapping from the unitary to doubly stochastic matrices and symbols on a finite set

NASA Astrophysics Data System (ADS)

Karabegov, Alexander V.

2008-11-01

We prove that the mapping from the unitary to doubly stochastic matrices that maps a unitary matrix (ukl) to the doubly stochastic matrix (|ukl|2) is a submersion at a generic unitary matrix. The proof uses the framework of operator symbols on a finite set.

Complete spatial and temporal locking in phase-mismatched second-harmonic generation.

PubMed

Fazio, Eugenio; Pettazzi, Federico; Centini, Marco; Chauvet, Mathieu; Belardini, Alessandro; Alonzo, Massimo; Sibilia, Concita; Bertolotti, Mario; Scalora, Micheal

2009-03-02

We experimentally demonstrate simultaneous phase and group velocity locking of fundamental and generated second harmonic pulses in Lithium Niobate, under conditions of material phase mismatch. In phase-mismatched, pulsed second harmonic generation in addition to a reflected signal two forward-propagating pulses are also generated at the interface between a linear and a second order nonlinear material: the first pulse results from the solution of the homogeneous wave equation, and propagates at the group velocity expected from material dispersion; the second pulse is the solution of the inhomogeneous wave equation, is phase-locked and trapped by the pump pulse, and follows the pump trajectory. At normal incidence, the normal and phase locked pulses simply trail each other. At oblique incidence, the consequences can be quite dramatic. The homogeneous pulse refracts as predicted by material dispersion and Snell's law, yielding at least two spatially separate second harmonic spots at the medium's exit. We thus report the first experimental results showing that, at oblique incidence, fundamental and phase-locked second harmonic pulses travel with the same group velocity and follow the same trajectory. This is direct evidence that, at least up to first order, the effective dispersion of the phase-locked pulse is similar to the dispersion of the pump pulse.

Quantum properties of double kicked systems with classical translational invariance in momentum

NASA Astrophysics Data System (ADS)

Dana, Itzhack

2015-01-01

Double kicked rotors (DKRs) appear to be the simplest nonintegrable Hamiltonian systems featuring classical translational symmetry in phase space (i.e., in angular momentum) for an infinite set of values (the rational ones) of a parameter η . The experimental realization of quantum DKRs by atom-optics methods motivates the study of the double kicked particle (DKP). The latter reduces, at any fixed value of the conserved quasimomentum β ℏ , to a generalized DKR, the "β -DKR ." We determine general quantum properties of β -DKRs and DKPs for arbitrary rational η . The quasienergy problem of β -DKRs is shown to be equivalent to the energy eigenvalue problem of a finite strip of coupled lattice chains. Exact connections are then obtained between quasienergy spectra of β -DKRs for all β in a generically infinite set. The general conditions of quantum resonance for β -DKRs are shown to be the simultaneous rationality of η ,β , and a scaled Planck constant ℏS. For rational ℏS and generic values of β , the quasienergy spectrum is found to have a staggered-ladder structure. Other spectral structures, resembling Hofstadter butterflies, are also found. Finally, we show the existence of particular DKP wave-packets whose quantum dynamics is free, i.e., the evolution frequencies of expectation values in these wave-packets are independent of the nonintegrability. All the results for rational ℏS exhibit unique number-theoretical features involving η ,ℏS, and β .

Coherent population transfer in multi-level Allen-Eberly models

NASA Astrophysics Data System (ADS)

Li, Wei; Cen, Li-Xiang

2018-04-01

We investigate the solvability of multi-level extensions of the Allen-Eberly model and the population transfer yielded by the corresponding dynamical evolution. We demonstrate that, under a matching condition of the frequency, the driven two-level system and its multi-level extensions possess a stationary-state solution in a canonical representation associated with a unitary transformation. As a consequence, we show that the resulting protocol is able to realize complete population transfer in a nonadiabatic manner. Moreover, we explore the imperfect pulsing process with truncation and display that the nonadiabatic effect in the evolution can lead to suppression to the cutoff error of the protocol.

Numerical Models of Stopping Ruptures on a Bimaterial Interface

NASA Astrophysics Data System (ADS)

Rubin, A. M.; Ampuero, J.

2003-12-01

Using a cross-correlation earthquake relocation technique, Rubin and Gillard (2000) and Rubin (2002) found that the nearest aftershocks of microearthquakes on the San Andreas fault were much more likely (by a ratio of nearly 3:1) to occur to the NW of the mainshock than to the SE. They attributed this asymmetry to the material contrast across the fault and the resulting dynamical reduction in normal stress near the rupture front propagating to the SE (the front moving in the direction of slip of the more compliant medium). Specifically, it was hypothesized that regions of the fault far enough from failure to resist this extra dynamical "kick" would be that much farther from failure once those dynamical stresses decayed. However, analytical (steady-state) models of propagating slip on a bimaterial interface (Weertman, 1980) show that, as with the static stress field, normal stress changes occur only behind the rupture front. The proposed explanation works most simply if the region ahead of the SE rupture front experiences a transient stress favorable for slip. In principal this stress transient could be associated with either rupture growth or arrest. To investigate this further, we ran 2-D numerical models of slip on a bimaterial interface with slip-weakening friction, using the code of Cochard and Rice (2000). The ruptures spontaneously accelerate to the generalized Rayleigh wave speed of the medium, when such exists. During this growth phase, large tensile stresses are indeed restricted to regions of large slip velocity behind the SE-propagating rupture front. Ahead of the rupture front the normal stresses are smaller and compressive. If the rupture front is stopped abruptly, the short-wavelength tensile stress pulse continues to propagate at roughly the same velocity. The above comments also apply in an anti-symmetric sense to the NW rupture front, although there the slip speeds and normal stress changes are lower. If the rupture is stopped by a more gradual reduction in the loading stress, the moving tensile pulse can spawn a decaying slip pulse at the SE front but not the NW. If this slip pulse marks the furthest extent of slip, the resulting static stress field is quite asymmetric even for a symmetric initial stress, lying on the failure envelope at the NW end of the rupture but well below it at the SE end. These results are at least permissive of the explanation proposed by Rubin and Gillard. For weaker slip pulses (due to any of a number of factors contributing to smaller maximum slip speeds), the furthest extent of slip near the SE rupture front can be driven by the stopping phase arriving from the NW end of the crack. Under such conditions the final stress field is more symmetric. We will be running models using heterogeneous stress fields to explore these questions further, and hope to use rate-and-state friction to investigate the observed temporal decay of the aftershock asymmetry.

Comparative study of the femoroacetabular impingement (FAI) prevalence in male semiprofessional and amateur soccer players.

PubMed

Lahner, Matthias; Walter, Philipp Alexander; von Schulze Pellengahr, Christoph; Hagen, Marco; von Engelhardt, Lars Victor; Lukas, Carsten

2014-08-01

Femoroacetabular impingement (FAI) represents a novel approach to the mechanical etiology of hip osteoarthritis. The cam-type femoroacetabular impingement deformity occurs frequently in young male athletes. The aim of our study was to evaluate the prevalence of FAI in male semiprofessional soccer players using clinical examination and magnetic resonance imaging (MRI), compared to amateur soccer players. In MRI, the α angle of Nötzli is determined for quantifying FAI. According to power analysis, a total of 22 asymptomatic semiprofessional soccer players with a median of 23.3 years of age (range 18-30 years) and 22 male amateur soccer players with a median of 22.5 years of age (control group, range 18-29 years) underwent an MRI to measure the hip α angle of Nötzli. The α angle of the kicking legs of the semiprofessional group and the amateur group were analyzed. The study group was moreover evaluated by the Hip Outcome Score (HOS) and a clinical hip examination including range of motion (ROM) and impingement tests. In the semiprofessional group, 19 soccer players had a right kicking leg and 1 soccer player had a left kicking leg. 2 soccer players kicked with two feet. In the semi-professional group, the mean value of the α angle of the kicking leg (57.3 ± 8.2°) was significantly higher than in the amateur group (51.7 ± 4.8°, P = 0.008). In the semi-professional group, 15 (62.5 %) of 24 kicking legs had an increased α angle >55°, while 5 (27.3 %) kicking legs of the amateur group had an α angle >55°. Five semi professional soccer players had findings in clinical examination, whereof 4 had an increased α angle >55°. No participant of the amateur group showed pathological results in the clinical examination (P = 0.0484). Overall, semiprofessional soccer players had a higher proportion of an increased α angle than the amateur group. Semiprofessional players have a higher prevalence of an increased α angle in the kicking leg than the amateur group at the same age. The kicking leg is predisposed for FAI.

A Kinematic Analysis of the Jumping Front-Leg Axe-Kick in Taekwondo

PubMed Central

Preuschl, Emanuel; Hassmann, Michaela; Baca, Arnold

2016-01-01

The jumping front-leg axe-kick is a valid attacking and counterattacking technique in Taekwondo competition (Streif, 1993). Yet, the existing literature on this technique is sparse (Kloiber et al., 2009). Therefore, the goal of this study was to determine parameters contributing significantly to maximum linear speed of the foot at impact. Parameters are timing of segment and joint angular velocity characteristics and segment lengths of the kicking leg. Moreover, we were interested in the prevalence of proximal-to-distal-sequencing. Three-dimensional kinematics of the kicks of 22 male Taekwondo-athletes (age: 23.3 ± 5.3 years) were recorded via a motion capturing system (Vicon Motion Systems Limited, Oxford, UK). The participants performed maximum effort kicks onto a rack-held kicking pad. Only the kick with the highest impact velocity was analysed, as it was assumed to represent the individual’s best performance. Significant Pearson correlations to impact velocity were found for pelvis tilt angular displacement (r = 0.468, p < 0.05) and for hip extension angular velocity (r = -0.446, p < 0.05) and for the timing of the minima of pelvis tilt velocity (r = -0.426, p < 0.05) and knee flexion velocity (r = -0.480, p < 0.05). Backward step linear regression analysis suggests a model consisting of three predictor variables: pelvis tilt angular displacement, hip flexion velocity at target contact and timing of pelvic tilt angular velocity minimum (adjusted R2 = 0.524). Results of Chi-Squared tests show that neither for the leg-raising period (χ2 = 2.909) of the technique, nor for the leg-lowering period a pattern of proximal-to-distal sequencing is prevalent (χ2 = 0.727). From the results we conclude that the jumping front-leg axe-kick does not follow a proximal-to-distal pattern. Raising the leg early in the technique and apprehending the upper body to be leant back during the leg-lowering period seems to be beneficial for high impact velocity. Furthermore, striking by extending the hip rather than by flexing the knee could raise impact velocity. Key points Angular velocity characteristics of the pelvis segment and the kicking leg’s hip and knee joint show no proximal-to-distal sequencing, neither for the leg-raising or leg-lowering period in a jumping front-leg axe-kick. Anthropometric parameters of taekwondo athlete’s do not influence their impact velocities. In order to raise the impact velocity in the jumping front-leg axe-kick an athlete should avoid tilting back with the torso. Instead, an upright position should be maintained. In the leg-lowering period, we suggest hitting the target by using hip extension with a rather straight knee, instead of flexing the knee. PMID:26957931

Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

NASA Astrophysics Data System (ADS)

Roppo, Vito; Centini, Marco; Sibilia, Concita; Bertolotti, Mario; de Ceglia, Domenico; Scalora, Michael; Akozbek, Neset; Bloemer, Mark J.; Haus, Joseph W.; Kosareva, Olga G.; Kandidov, Valery P.

2007-09-01

The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is “captured” and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not only second-harmonic generation, but also χ(3) processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part of the same pulse initially generated at the surface, part of which is immediately back-reflected, while the rest becomes trapped and dragged along by the pump pulse. These pulses thus constitute twin pulses generated at the interface, having the same negative wave vector, but propagating in opposite directions. Almost any break of the longitudinal symmetry, even an exceedingly small χ(2) discontinuity, releases the trapped pulse which then propagates in the backward direction. These dynamics are indicative of very rich and intricate interactions that characterize ultrashort pulse propagation phenomena.

Role of phase matching in pulsed second-harmonic generation: Walk-off and phase-locked twin pulses in negative-index media

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

Roppo, Vito; Centini, Marco; Sibilia, Concita

The present investigation is concerned with the study of pulsed second-harmonic generation under conditions of phase and group velocity mismatch, and generally low conversion efficiencies and pump intensities. In positive-index, nonmetallic materials, we generally find qualitative agreement with previous reports regarding the presence of a double-peaked second harmonic signal, which comprises a pulse that walks off and propagates at the nominal group velocity one expects at the second-harmonic frequency, and a second pulse that is 'captured' and propagates under the pump pulse. We find that the origin of the double-peaked structure resides in a phase-locking mechanism that characterizes not onlymore » second-harmonic generation, but also {chi}{sup (3)} processes and third-harmonic generation. The phase-locking mechanism that we describe occurs for arbitrarily small pump intensities, and so it is not a soliton effect, which usually relies on a threshold mechanism, although multicolor solitons display similar phase locking characteristics. Thus, in second harmonic generation a phase-matched component is always generated, even under conditions of material phase mismatch: This component is anomalous, because the material does not allow energy exchange between the pump and the second-harmonic beam. On the other hand, if the material is phase matched, phase locking and phase matching are indistinguishable, and the conversion process becomes efficient. We also report a similar phase-locking phenomenon in negative index materials. A spectral analysis of the pump and the generated signals reveals that the phase-locking phenomenon causes the forward moving, phase-locked second-harmonic pulse to experience the same negative index as the pump pulse, even though the index of refraction at the second-harmonic frequency is positive. Our analysis further shows that the reflected second-harmonic pulse generated at the interface and the forward-moving, phase-locked pulse appear to be part of the same pulse initially generated at the surface, part of which is immediately back-reflected, while the rest becomes trapped and dragged along by the pump pulse. These pulses thus constitute twin pulses generated at the interface, having the same negative wave vector, but propagating in opposite directions. Almost any break of the longitudinal symmetry, even an exceedingly small {chi}{sup (2)} discontinuity, releases the trapped pulse which then propagates in the backward direction. These dynamics are indicative of very rich and intricate interactions that characterize ultrashort pulse propagation phenomena.« less

Biomechanics of head injury in olympic taekwondo and boxing.

PubMed

Fife, G P; O'Sullivan, D; Pieter, W

2013-12-01

The purpose was to examine differences between taekwondo kicks and boxing punches in resultant linear head acceleration (RLA), head injury criterion (HIC15), peak head velocity, and peak foot and fist velocities. Data from two existing publications on boxing punches and taekwondo kicks were compared. For taekwondo head impacts a Hybrid II Crash Dummy (Hybrid II) head was instrumented with a tri-axial accelerometer mounted inside the Hybrid II head. The Hybrid II was fixed to a height-adjustable frame and fitted with a protective taekwondo helmet. For boxing testing, a Hybrid III Crash Dummy head was instrumented with an array of tri-axial accelerometers mounted at the head centre of gravity. Differences in RLA between the roundhouse kick (130.11±51.67 g) and hook punch (71.23±32.19 g, d = 1.39) and in HIC15 (clench axe kick: 162.63±104.10; uppercut: 24.10±12.54, d = 2.29) were observed. Taekwondo kicks demonstrated significantly larger magnitudes than boxing punches for both RLA and HIC.

Coherent combining of pulsed fiber amplifiers in the nonlinear chirp regime with intra-pulse phase control.

PubMed

Palese, Stephen; Cheung, Eric; Goodno, Gregory; Shih, Chun-Ching; Di Teodoro, Fabio; McComb, Timothy; Weber, Mark

2012-03-26

Two high pulse contrast (> 95 dB) polarization maintaining all-fiber amplifier chains were coherently combined to generate 0.42 mJ, 1 ns 25 kHz pulses with 79% efficiency despite 38 radians of intra-pulse phase distortion. A recursive intra-pulse phase compensation method was utilized to correct for the large nonlinear chirp providing a path for improved coherent waveform control of nanosecond pulse trains.

Convolutional Architecture Exploration for Action Recognition and Image Classification

DTIC Science & Technology

2015-01-01

that has 200 videos taken in 720x480 resolution of 9 different sporting activities: diving, golf , swinging , kicking, lifting, horseback riding, running...sporting activities: diving, golf swinging , kicking, lifting, horseback riding, running, skateboarding, swinging (various gymnastics), and walking. In this...Testing Videos Diving 13 3 Golf Swinging 21 4 Horseback Riding 11 3 Kicking 21 4 Lifting 12 3 Running 12 3 Skateboarding 12 3 Swinging (Gymnastics) 28

Things May Not Always Be as They Seem: The Set Shot in AFL Football

ERIC Educational Resources Information Center

Galbraith, Peter; Lockwood, Terry

2010-01-01

In this article, the authors investigate how the difficulty of a "set shot" at goal varies with position on the field. By "set shot" they mean a player kicking for goal following a mark or free kick. The analysis begins by defining the "angle of opportunity" as a measure of difficulty for kicks at a given distance and angle from goal, where the…

Estimating gas kick arrival to better manage surface flow

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

Merryman, J.

1997-06-01

There are many quality, expertly designed programs for teaching rig crews prevention and control of well kicks. Much time and money has been spent training rig crews for procedures and methods to avoid kicks, and what to do if you have one, even though all accepted practices were followed. One false/bad result from this training is that individuals have come away from this training believing that once a gas kick is circulated through the choke, all problems are simple and manageable, i.e., the danger has passed. What you do with gas once it is downstream of the choke has notmore » been given enough emphasis in some training programs, including the one the author is involved in. This article, prepared from experiences on actual rig locations in Wyoming and Argentina, and developed for well control training in Parker Drilling Co.`s Training Center, Odessa, Texas, describes a method for estimating the time, in pump strokes and/or minutes, for a gas kick to reach surface. Reducing pump strokes (circulating flowrate) and knowing available time to gas kick arrival allows the crew to prepare surface handling equipment. Common misconceptions about gas handling and potential resulting problems are noted. An example calculation describes the calculation procedure.« less

Binary Black Hole Mergers and Recoil Kicks

NASA Technical Reports Server (NTRS)

Centrella, Joan; Baker, J.; Choi, D.; Koppitz, M.; vanMeter, J.; Miller, C.

2006-01-01

Recent developments in numerical relativity have made it possible to follow reliably the coalescence of two black holes from near the innermost stable circular orbit to final ringdown. This opens up a wide variety of exciting astrophysical applications of these simulations. Chief among these is the net kick received when two unequal mass or spinning black holes merge. The magnitude of this kick has bearing on the production and growth of supermassive black holes during the epoch of structure formation, and on the retention of black holes in stellar clusters. Here we report the first accurate numerical calculation of this kick, for two nonspinning black holes in a 1.5:1 mass ratio, which is expected based on analytic considerations to give a significant fraction of the maximum possible recoil. We have performed multiple runs with different initial separations, orbital angular momenta, resolutions, extraction radii, and gauges. The full range of our kick speeds is 86-116 kilometers per second, and the most reliable runs give kicks between 86 and 97 kilometers per second. This is intermediate between the estimates from two recent post-Newtonian analyses and suggests that at redshifts z greater than 10, halos with masses less than 10(exp 9) M(sub SUN) will have difficulty retaining coalesced black holes after major mergers.

X-ray light curves of active galactic nuclei are phase incoherent

NASA Technical Reports Server (NTRS)

Krolik, Julian; Done, Chris; Madejski, Grzegorz

1993-01-01

We compute the Fourier phase spectra for the light curves of five low-luminosity active galactic nuclei observed by EXOSAT. There is no statistically significant phase coherence in any of them. This statement is equivalent, subject to a technical caveat, to a demonstration that their fluctuation statistics are Gaussian. Models in which the X-ray output is controlled wholly by a unitary process undergoing a nonlinear limit cycle are therefore ruled out, while models with either a large number of randomly excited independent oscillation modes or nonlinearly interacting spatially dependent oscillations are favored. We also demonstrate how the degree of phase coherence in light curve fluctuations influences the application of causality bounds on internal length scales.

Influence of the distance in a roundhouse kick's execution time and impact force in Taekwondo.

PubMed

Falco, Coral; Alvarez, Octavio; Castillo, Isabel; Estevan, Isaac; Martos, Julio; Mugarra, Fernando; Iradi, Antonio

2009-02-09

Taekwondo, originally a Korean martial art, is well known for its kicks. One of the most frequently used kicks in competition is Bandal Chagui or roundhouse kick. Excellence in Taekwondo relies on the ability to make contact with the opponent's trunk or face with enough force in as little time as possible, while at the same time avoiding being hit. Thus, the distance between contestants is an important variable to be taken into consideration. Thirty-one Taekwondo athletes in two different groups (expert and novice, according to experience in competition) took part in this study. The purpose of this study was to examine both impact force and execution time in a Bandal Chagui or roundhouse kick, and to explore the effect of execution distance in these two variables. A new model was developed in order to measure the force exerted by the body on a load. A force platform and a contact platform were used to measure these variables. The results showed that there are no significant differences in terms of impact force in relation to execution distance in expert competitors. Significant and positive correlations between body mass and impact force (p<.01) seem to mean that novice competitors use their body mass to generate high impact forces. Significant differences were found in competitive experience and execution time for the three different distances of kicking considered in the study. Standing at a certain further distance from the opponent should be an advantage for competitors who are used to kick from a further distance in their training.

The evaluation of lyophilized polymer matrices for administering recombinant human bone morphogenetic protein-2.

PubMed

Duggirala, S S; Rodgers, J B; DeLuca, P P

1996-07-01

Novel unitary devices, prepared by lyophilization of viscous solutions of sodium carboxymethylcellulose (CMC) and methylcellulose (MC), were evaluated as sustained-release delivery systems for recombinant human bone morphogenetic protein-2 (rhBMP-2). In vitro characterization of the unitary devices, which contained rhBMP-2-loaded poly (d,l lactide-co-glycolide) (PLGA) bioerodible particles (BEPs), was conducted over a 2-month period. Determinations included buffer uptake, mass and molecular weight loss and rhBMP-2 release from the unitary devices. CMC devices imbibed approximately 16 times their weight of buffer, while with MC, equilibrium uptake was approximately 6 times the dry weight of the devices. Overall mass loss percentages were approximately 55 and 35%, respectively, for CMC and MC devices. rhBMP-2 release from the devices was essentially a triphasic process: an initial phase during which "free" protein (rhBMP-2 present on the surface and within the pores of the PLGA BEPs) was released, a lag period during which no release was discerned, and then release of "bound" rhBMP-2 (protein adsorbed to the BEPs). The release of bound protein correlated with the mass loss of the polymer which began after 3 weeks. Release from the unitary devices was lower than that from the BEPs alone, due to a retardation effect of the gelled CMC/MC polymers. In rabbits in which full-thickness cranial bone defects were created, the implants were well tolerated and induced significant new bone growth during an 8-week evaluation period. The CMC devices appear to have induced bone earlier (at 2 weeks), but this did not affect eventual 8-week results. CMC devices without rhBMP-2 appeared to provide some bone conduction, in contrast to the blank MC devices.

Quantum computation over the butterfly network

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

Soeda, Akihito; Kinjo, Yoshiyuki; Turner, Peter S.

2011-07-15

In order to investigate distributed quantum computation under restricted network resources, we introduce a quantum computation task over the butterfly network where both quantum and classical communications are limited. We consider deterministically performing a two-qubit global unitary operation on two unknown inputs given at different nodes, with outputs at two distinct nodes. By using a particular resource setting introduced by M. Hayashi [Phys. Rev. A 76, 040301(R) (2007)], which is capable of performing a swap operation by adding two maximally entangled qubits (ebits) between the two input nodes, we show that unitary operations can be performed without adding any entanglementmore » resource, if and only if the unitary operations are locally unitary equivalent to controlled unitary operations. Our protocol is optimal in the sense that the unitary operations cannot be implemented if we relax the specifications of any of the channels. We also construct protocols for performing controlled traceless unitary operations with a 1-ebit resource and for performing global Clifford operations with a 2-ebit resource.« less

Adiabatic leakage elimination operator in an experimental framework

NASA Astrophysics Data System (ADS)

Wang, Zhao-Ming; Byrd, Mark S.; Jing, Jun; Wu, Lian-Ao

2018-06-01

Adiabatic evolution is used in a variety of quantum information processing tasks. However, the elimination of errors is not as well developed as it is for circuit model processing. Here, we present a strategy to improve the performance of a quantum adiabatic process by adding leakage elimination operators (LEOs) to the evolution. These are a sequence of pulse controls acting in an adiabatic subspace to eliminate errors by suppressing unwanted transitions. Using the Feshbach P Q partitioning technique, we obtain an analytical solution for a set of pulse controls. The effectiveness of the LEO is independent of the specific form of the pulse but depends on the average frequency of the control function. By observing that the evolution of the target eigenstate is governed by a periodic function appearing in the integral of the control function, we show that control parameters can be chosen in such a way that the instantaneous eigenstates of the system are unchanged, yet a speedup can be achieved by suppressing transitions. Furthermore, we give the exact expression of the control function for a counter unitary transformation to be used in experiments which provides a clear physical meaning for the LEO, aiding in the implementation.

Meditations on the unitary rhythm of dying-grieving.

PubMed

Malinski, Violet M

2012-07-01

When someone faces loss of a loved one, that person simultaneously grieves and dies a little, just as the one dying also grieves. The author's personal conceptualization of dying and grieving as a unitary rhythm is explored based primarily on her interpretation of Rogers' science of unitary human beings, along with selected examples from related nursing literature and from the emerging focus on continuing bonds in other disciplines. Examples from contemporary songwriters that depict such a unitary conceptualization are given along with personal examples. The author concludes with her description of the unitary rhythm of dying-grieving.

Influence of the cubic spectral phase of high-power laser pulses on their self-phase modulation

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

Ginzburg, V N; Kochetkov, A A; Yakovlev, I V

2016-02-28

Spectral broadening of high-power transform-limited laser pulses under self-phase modulation in a medium with cubic nonlinearity is widely used to reduce pulse duration and to increase its power. It is shown that the cubic spectral phase of the initial pulse leads to a qualitatively different broadening of its spectrum: the spectrum has narrow peaks and broadening decreases. However, the use of chirped mirrors allows such pulses to be as effectively compressed as transform-limited pulses. (nonlinear optical phenomena)

Lossless and Sufficient - Invariant Decomposition of Deterministic Target

NASA Astrophysics Data System (ADS)

Paladini, Riccardo; Ferro Famil, Laurent; Pottier, Eric; Martorella, Marco; Berizzi, Fabrizio

2011-03-01

The symmetric radar scattering matrix of a reciprocal target is projected on the circular polarization basis and is decomposed into four orientation invariant parameters, relative phase and relative orientation. The physical interpretation of this results is found in the wave-particle nature of radar scattering due to the circular polarization nature of elemental packets of energy. The proposed decomposition, is based on left orthogonal to left Special Unitary basis, providing the target description in term of a unitary vector. A comparison between the proposed CTD and Cameron, Kennaugh and Krogager decompositions is also pointed out. A validation by the use of both anechoic chamber data and airborne EMISAR data of DTU is used to show the effectiveness of this decomposition for the analysis of coherent targets. In the second paper we will show the application of the rotation group U(3) for the decomposition of distributed targets into nine meaningful parameters.

Majorana-Based Fermionic Quantum Computation.

PubMed

O'Brien, T E; Rożek, P; Akhmerov, A R

2018-06-01

Because Majorana zero modes store quantum information nonlocally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majorana modes to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majorana modes for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum phase estimation algorithms, proposed for quantum chemistry simulations. Because we avoid the Jordan-Wigner transformation, our scheme has a lower overhead for implementing both of these algorithms, allowing for simulation of the Trotterized Hubbard Hamiltonian in O(1) time per unitary step. We finally demonstrate magic state distillation in our fermionic architecture, giving a universal set of topologically protected fermionic quantum gates.

Majorana-Based Fermionic Quantum Computation

NASA Astrophysics Data System (ADS)

O'Brien, T. E.; RoŻek, P.; Akhmerov, A. R.

2018-06-01

Because Majorana zero modes store quantum information nonlocally, they are protected from noise, and have been proposed as a building block for a quantum computer. We show how to use the same protection from noise to implement universal fermionic quantum computation. Our architecture requires only two Majorana modes to encode a fermionic quantum degree of freedom, compared to alternative implementations which require a minimum of four Majorana modes for a spin quantum degree of freedom. The fermionic degrees of freedom support both unitary coupled cluster variational quantum eigensolver and quantum phase estimation algorithms, proposed for quantum chemistry simulations. Because we avoid the Jordan-Wigner transformation, our scheme has a lower overhead for implementing both of these algorithms, allowing for simulation of the Trotterized Hubbard Hamiltonian in O (1 ) time per unitary step. We finally demonstrate magic state distillation in our fermionic architecture, giving a universal set of topologically protected fermionic quantum gates.

Quantumness-generating capability of quantum dynamics

NASA Astrophysics Data System (ADS)

Li, Nan; Luo, Shunlong; Mao, Yuanyuan

2018-04-01

We study quantumness-generating capability of quantum dynamics, where quantumness refers to the noncommutativity between the initial state and the evolving state. In terms of the commutator of the square roots of the initial state and the evolving state, we define a measure to quantify the quantumness-generating capability of quantum dynamics with respect to initial states. Quantumness-generating capability is absent in classical dynamics and hence is a fundamental characteristic of quantum dynamics. For qubit systems, we present an analytical form for this measure, by virtue of which we analyze several prototypical dynamics such as unitary dynamics, phase damping dynamics, amplitude damping dynamics, and random unitary dynamics (Pauli channels). Necessary and sufficient conditions for the monotonicity of quantumness-generating capability are also identified. Finally, we compare these conditions for the monotonicity of quantumness-generating capability with those for various Markovianities and illustrate that quantumness-generating capability and quantum Markovianity are closely related, although they capture different aspects of quantum dynamics.

Phase Space Tweezers for Tailoring Cavity Fields by Quantum Zeno Dynamics

NASA Astrophysics Data System (ADS)

Raimond, J. M.; Sayrin, C.; Gleyzes, S.; Dotsenko, I.; Brune, M.; Haroche, S.; Facchi, P.; Pascazio, S.

2010-11-01

We discuss an implementation of quantum Zeno dynamics in a cavity quantum electrodynamics experiment. By performing repeated unitary operations on atoms coupled to the field, we restrict the field evolution in chosen subspaces of the total Hilbert space. This procedure leads to promising methods for tailoring nonclassical states. We propose to realize “tweezers” picking a coherent field at a point in phase space and moving it towards an arbitrary final position without affecting other nonoverlapping coherent components. These effects could be observed with a state-of-the-art apparatus.

Three-dimensional dualities with bosons and fermions

NASA Astrophysics Data System (ADS)

Benini, Francesco

2018-02-01

We propose new infinite families of non-supersymmetric IR dualities in three space-time dimensions, between Chern-Simons gauge theories (with classical gauge groups) with both scalars and fermions in the fundamental representation. In all cases we study the phase diagram as we vary two relevant couplings, finding interesting lines of phase transitions. In various cases the dualities lead to predictions about multi-critical fixed points and the emergence of IR quantum symmetries. For unitary groups we also discuss the coupling to background gauge fields and the map of simple monopole operators.

Classification of symmetry-protected phases for interacting fermions in two dimensions

NASA Astrophysics Data System (ADS)

Cheng, Meng; Bi, Zhen; You, Yi-Zhuang; Gu, Zheng-Cheng

2018-05-01

Recently, it has been established that two-dimensional bosonic symmetry-protected topological (SPT) phases with on-site unitary symmetry G can be completely classified by the group cohomology H3( G ,U (1 ) ) . Later, group supercohomology was proposed as a partial classification for SPT phases of interacting fermions. In this work, we revisit this problem based on the algebraic theory of symmetry and defects in two-dimensional topological phases. We reproduce the partial classifications given by group supercohomology, and we also show that with an additional H1(G ,Z2) structure, a complete classification of SPT phases for two-dimensional interacting fermion systems with a total symmetry group G ×Z2f is obtained. We also discuss the classification of interacting fermionic SPT phases protected by time-reversal symmetry.

REVIEWS OF TOPICAL PROBLEMS: Global phase-stable radiointerferometric systems

NASA Astrophysics Data System (ADS)

Dravskikh, A. F.; Korol'kov, Dimitrii V.; Pariĭskiĭ, Yu N.; Stotskiĭ, A. A.; Finkel'steĭn, A. M.; Fridman, P. A.

1981-12-01

We discuss from a unitary standpoint the possibility of building a phase-stable interferometric system with very long baselines that operate around the clock with real-time data processing. The various problems involved in the realization of this idea are discussed: the methods of suppression of instrumental and tropospheric phase fluctuations, the methods for constructing two-dimensional images and determining the coordinates of radio sources with high angular resolution, and the problem of the optimal structure of the interferometric system. We review in detail the scientific problems from the various branches of natural science (astrophysics, cosmology, geophysics, geodynamics, astrometry, etc.) whose solution requires superhigh angular resolution.

High-power parametric amplification of 11.8-fs laser pulses with carrier-envelope phase control.

PubMed

Zinkstok, R Th; Witte, S; Hogervorst, W; Eikema, K S E

2005-01-01

Phase-stable parametric chirped-pulse amplification of ultrashort pulses from a carrier-envelope phase-stabilized mode-locked Ti:sapphire oscillator (11.0 fs) to 0.25 mJ/pulse at 1 kHz is demonstrated. Compression with a grating compressor and a LCD shaper yields near-Fourier-limited 11.8-fs pulses with an energy of 0.12 mJ. The amplifier is pumped by 532-nm pulses from a synchronized mode-locked laser, Nd:YAG amplifier system. This approach is shown to be promising for the next generation of ultrafast amplifiers aimed at producing terawatt-level phase-controlled few-cycle laser pulses.

Carrier-envelope phase-stabilized attosecond pulses from asymmetric molecules

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

Lan Pengfei; Lu Peixiang; Cao Wei

2007-08-15

High-order harmonic generation from asymmetric molecules is investigated, and the concept of phase-stabilized infrared ultrashort laser pulses is extended to the extreme ultraviolet regime. It is shown that the ionization symmetry in consecutive half optical cycles is broken for asymmetric molecules, and both even and odd harmonics with comparable intensity are produced. In the time domain, only one attosecond pulse is generated in each cycle of the driving field, and the carrier-envelope phases of the attosecond pulses are equal. Consequently, a clean attosecond pulse train with the same carrier-envelope phase from pulse to pulse is obtained in the extreme ultravioletmore » regime.« less

Generation of ultra-wideband triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion.

PubMed

Li, Wei; Wang, Li Xian; Hofmann, Werner; Zhu, Ning Hua; Bimberg, Dieter

2012-08-27

We propose and demonstrate a novel scheme to generate ultra-wideband (UWB) triplet pulses based on four-wave mixing and phase-to-intensity modulation conversion. First a phase-modulated Gaussian doublet pulse is generated by four-wave mixing in a highly nonlinear fiber. Then an UWB triplet pulse is generated by generating the first-order derivative of the phase-modulated Gaussian doublet pulse using an optical filter serving as a frequency discriminator. By locating the optical signal at the linear slope of the optical filter, the phase modulated Gaussian doublet pulse is converted to an intensity-modulated UWB triplet pulse which well satisfies the Federal Communications Commission spectral mask requirements, even in the extremely power-restricted global positioning system band.

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Nie, Yongming; Ma, Haotong; Li, Xiujian; Hu, Wenhua; Yang, Jiankun

2011-07-01

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230fs, which is caused by the spatial--temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged.

Active control of the spatial MRI phase distribution with optimal control theory

NASA Astrophysics Data System (ADS)

Lefebvre, Pauline M.; Van Reeth, Eric; Ratiney, Hélène; Beuf, Olivier; Brusseau, Elisabeth; Lambert, Simon A.; Glaser, Steffen J.; Sugny, Dominique; Grenier, Denis; Tse Ve Koon, Kevin

2017-08-01

This paper investigates the use of Optimal Control (OC) theory to design Radio-Frequency (RF) pulses that actively control the spatial distribution of the MRI magnetization phase. The RF pulses are generated through the application of the Pontryagin Maximum Principle and optimized so that the resulting transverse magnetization reproduces various non-trivial and spatial phase patterns. Two different phase patterns are defined and the resulting optimal pulses are tested both numerically with the ODIN MRI simulator and experimentally with an agar gel phantom on a 4.7 T small-animal MR scanner. Phase images obtained in simulations and experiments are both consistent with the defined phase patterns. A practical application of phase control with OC-designed pulses is also presented, with the generation of RF pulses adapted for a Magnetic Resonance Elastography experiment. This study demonstrates the possibility to use OC-designed RF pulses to encode information in the magnetization phase and could have applications in MRI sequences using phase images.

Anderson transition in a three-dimensional kicked rotor

NASA Astrophysics Data System (ADS)

Wang, Jiao; García-García, Antonio M.

2009-03-01

We investigate Anderson localization in a three-dimensional (3D) kicked rotor. By a finite-size scaling analysis we identify a mobility edge for a certain value of the kicking strength k=kc . For k>kc dynamical localization does not occur, all eigenstates are delocalized and the spectral correlations are well described by Wigner-Dyson statistics. This can be understood by mapping the kicked rotor problem onto a 3D Anderson model (AM) where a band of metallic states exists for sufficiently weak disorder. Around the critical region k≈kc we carry out a detailed study of the level statistics and quantum diffusion. In agreement with the predictions of the one parameter scaling theory (OPT) and with previous numerical simulations, the number variance is linear, level repulsion is still observed, and quantum diffusion is anomalous with ⟨p2⟩∝t2/3 . We note that in the 3D kicked rotor the dynamics is not random but deterministic. In order to estimate the differences between these two situations we have studied a 3D kicked rotor in which the kinetic term of the associated evolution matrix is random. A detailed numerical comparison shows that the differences between the two cases are relatively small. However in the deterministic case only a small set of irrational periods was used. A qualitative analysis of a much larger set suggests that deviations between the random and the deterministic kicked rotor can be important for certain choices of periods. Heuristically it is expected that localization effects will be weaker in a nonrandom potential since destructive interference will be less effective to arrest quantum diffusion. However we have found that certain choices of irrational periods enhance Anderson localization effects.

Core shroud corner joints

DOEpatents

Gilmore, Charles B.; Forsyth, David R.

2013-09-10

A core shroud is provided, which includes a number of planar members, a number of unitary corners, and a number of subassemblies each comprising a combination of the planar members and the unitary corners. Each unitary corner comprises a unitary extrusion including a first planar portion and a second planar portion disposed perpendicularly with respect to the first planar portion. At least one of the subassemblies comprises a plurality of the unitary corners disposed side-by-side in an alternating opposing relationship. A plurality of the subassemblies can be combined to form a quarter perimeter segment of the core shroud. Four quarter perimeter segments join together to form the core shroud.

The effect of plyometric training on power and kicking distance in female adolescent soccer players.

PubMed

Rubley, Mack D; Haase, Amaris C; Holcomb, William R; Girouard, Tedd J; Tandy, Richard D

2011-01-01

The purpose of this study was to measure the effects of low-frequency, low-impact plyometric training on vertical jump (VJ) and kicking distance in female adolescent soccer players. Sixteen adolescent soccer players were studied (age 13.4 ± 0.5 years) across 14 weeks. The control group (general soccer training only) had 6 subjects, and the plyometric training (general soccer training plus plyometric exercise) group had 10 subjects. All subjects were tested for VJ and kicking distance on 3 occasions: pre-test, 7 weeks, and 14 weeks. Data were analyzed using a 2 (Training) × 3 (Test) analysis of variance (ANOVA) with repeated measures on the factor test. No significant difference in kicking distance was found between groups at pre-test (p = 0.688) or 7 weeks (p = 0.117). The plyometric group had significantly greater kicking distance after 14 weeks (p < 0.001). No significant difference in VJ height was found between groups at pre-test (p = 0.837) or 7 weeks (p = 0.108). The plyometric group had a significantly higher VJ after 14 weeks (p = 0.014). These results provide strength coaches with a safe and effective alternative to high-intensity plyometric training. Based on these findings, to increase lower-body power resulting in increased VJ and kicking distance, strength coaches should implement once-weekly, low-impact plyometric training programs with their adolescent athletes.

Method and apparatus for controlling carrier envelope phase

DOEpatents

Chang, Zenghu [Manhattan, KS; Li, Chengquan [Sunnyvale, CA; Moon, Eric [Manhattan, KS

2011-12-06

A chirped pulse amplification laser system. The system generally comprises a laser source, a pulse modification apparatus including first and second pulse modification elements separated by a separation distance, a positioning element, a measurement device, and a feedback controller. The laser source is operable to generate a laser pulse and the pulse modification apparatus operable to modify at least a portion of the laser pulse. The positioning element is operable to reposition at least a portion of the pulse modification apparatus to vary the separation distance. The measurement device is operable to measure the carrier envelope phase of the generated laser pulse and the feedback controller is operable to control the positioning element based on the measured carrier envelope phase to vary the separation distance of the pulse modification elements and control the carrier envelope phase of laser pulses generated by the laser source.

Phase-factor-dependent symmetries and quantum phases in a three-level cavity QED system.

PubMed

Fan, Jingtao; Yu, Lixian; Chen, Gang; Jia, Suotang

2016-05-03

Unlike conventional two-level particles, three-level particles may support some unitary-invariant phase factors when they interact coherently with a single-mode quantized light field. To gain a better understanding of light-matter interaction, it is thus necessary to explore the phase-factor-dependent physics in such a system. In this report, we consider the collective interaction between degenerate V-type three-level particles and a single-mode quantized light field, whose different components are labeled by different phase factors. We mainly establish an important relation between the phase factors and the symmetry or symmetry-broken physics. Specifically, we find that the phase factors affect dramatically the system symmetry. When these symmetries are breaking separately, rich quantum phases emerge. Finally, we propose a possible scheme to experimentally probe the predicted physics of our model. Our work provides a way to explore phase-factor-induced nontrivial physics by introducing additional particle levels.

Three-dimensional kinematic correlates of ball velocity during maximal instep soccer kicking in males.

PubMed

Sinclair, Jonathan; Fewtrell, David; Taylor, Paul John; Bottoms, Lindsay; Atkins, Stephen; Hobbs, Sarah Jane

2014-01-01

Achieving a high ball velocity is important during soccer shooting, as it gives the goalkeeper less time to react, thus improving a player's chance of scoring. This study aimed to identify important technical aspects of kicking linked to the generation of ball velocity using regression analyses. Maximal instep kicks were obtained from 22 academy-level soccer players using a 10-camera motion capture system sampling at 500 Hz. Three-dimensional kinematics of the lower extremity segments were obtained. Regression analysis was used to identify the kinematic parameters associated with the development of ball velocity. A single biomechanical parameter; knee extension velocity of the kicking limb at ball contact Adjusted R(2) = 0.39, p ≤ 0.01 was obtained as a significant predictor of ball-velocity. This study suggests that sagittal plane knee extension velocity is the strongest contributor to ball velocity and potentially overall kicking performance. It is conceivable therefore that players may benefit from exposure to coaching and strength techniques geared towards the improvement of knee extension angular velocity as highlighted in this study.

Effective time-independent analysis for quantum kicked systems.

PubMed

Bandyopadhyay, Jayendra N; Guha Sarkar, Tapomoy

2015-03-01

We present a mapping of potentially chaotic time-dependent quantum kicked systems to an equivalent approximate effective time-independent scenario, whereby the system is rendered integrable. The time evolution is factorized into an initial kick, followed by an evolution dictated by a time-independent Hamiltonian and a final kick. This method is applied to the kicked top model. The effective time-independent Hamiltonian thus obtained does not suffer from spurious divergences encountered if the traditional Baker-Cambell-Hausdorff treatment is used. The quasienergy spectrum of the Floquet operator is found to be in excellent agreement with the energy levels of the effective Hamiltonian for a wide range of system parameters. The density of states for the effective system exhibits sharp peaklike features, pointing towards quantum criticality. The dynamics in the classical limit of the integrable effective Hamiltonian shows remarkable agreement with the nonintegrable map corresponding to the actual time-dependent system in the nonchaotic regime. This suggests that the effective Hamiltonian serves as a substitute for the actual system in the nonchaotic regime at both the quantum and classical level.

Effective time-independent analysis for quantum kicked systems

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Jayendra N.; Guha Sarkar, Tapomoy

2015-03-01

We present a mapping of potentially chaotic time-dependent quantum kicked systems to an equivalent approximate effective time-independent scenario, whereby the system is rendered integrable. The time evolution is factorized into an initial kick, followed by an evolution dictated by a time-independent Hamiltonian and a final kick. This method is applied to the kicked top model. The effective time-independent Hamiltonian thus obtained does not suffer from spurious divergences encountered if the traditional Baker-Cambell-Hausdorff treatment is used. The quasienergy spectrum of the Floquet operator is found to be in excellent agreement with the energy levels of the effective Hamiltonian for a wide range of system parameters. The density of states for the effective system exhibits sharp peaklike features, pointing towards quantum criticality. The dynamics in the classical limit of the integrable effective Hamiltonian shows remarkable agreement with the nonintegrable map corresponding to the actual time-dependent system in the nonchaotic regime. This suggests that the effective Hamiltonian serves as a substitute for the actual system in the nonchaotic regime at both the quantum and classical level.

BIOMECHANICS OF HEAD INJURY IN OLYMPIC TAEKWONDO AND BOXING

PubMed Central

Fife, G.P.; Pieter, W.

2013-01-01

Objective The purpose was to examine differences between taekwondo kicks and boxing punches in resultant linear head acceleration (RLA), head injury criterion (HIC15), peak head velocity, and peak foot and fist velocities. Data from two existing publications on boxing punches and taekwondo kicks were compared. Methods For taekwondo head impacts a Hybrid II Crash Dummy (Hybrid II) head was instrumented with a tri-axial accelerometer mounted inside the Hybrid II head. The Hybrid II was fixed to a height-adjustable frame and fitted with a protective taekwondo helmet. For boxing testing, a Hybrid III Crash Dummy head was instrumented with an array of tri-axial accelerometers mounted at the head centre of gravity. Results Differences in RLA between the roundhouse kick (130.11±51.67 g) and hook punch (71.23±32.19 g, d = 1.39) and in HIC15 (clench axe kick: 162.63±104.10; uppercut: 24.10±12.54, d = 2.29) were observed. Conclusions Taekwondo kicks demonstrated significantly larger magnitudes than boxing punches for both RLA and HIC. PMID:24744497

Formation of Double Neutron Star Systems

NASA Astrophysics Data System (ADS)

Tauris, T. M.; Kramer, M.; Freire, P. C. C.; Wex, N.; Janka, H.-T.; Langer, N.; Podsiadlowski, Ph.; Bozzo, E.; Chaty, S.; Kruckow, M. U.; van den Heuvel, E. P. J.; Antoniadis, J.; Breton, R. P.; Champion, D. J.

2017-09-01

Double neutron star (DNS) systems represent extreme physical objects and the endpoint of an exotic journey of stellar evolution and binary interactions. Large numbers of DNS systems and their mergers are anticipated to be discovered using the Square Kilometre Array searching for radio pulsars, and the high-frequency gravitational wave detectors (LIGO/VIRGO), respectively. Here we discuss all key properties of DNS systems, as well as selection effects, and combine the latest observational data with new theoretical progress on various physical processes with the aim of advancing our knowledge on their formation. We examine key interactions of their progenitor systems and evaluate their accretion history during the high-mass X-ray binary stage, the common envelope phase, and the subsequent Case BB mass transfer, and argue that the first-formed NSs have accreted at most ˜ 0.02 {M}⊙ . We investigate DNS masses, spins, and velocities, and in particular correlations between spin period, orbital period, and eccentricity. Numerous Monte Carlo simulations of the second supernova (SN) events are performed to extrapolate pre-SN stellar properties and probe the explosions. All known close-orbit DNS systems are consistent with ultra-stripped exploding stars. Although their resulting NS kicks are often small, we demonstrate a large spread in kick magnitudes that may, in general, depend on the past interaction history of the exploding star and thus correlate with the NS mass. We analyze and discuss NS kick directions based on our SN simulations. Finally, we discuss the terminal evolution of close-orbit DNS systems until they merge and possibly produce a short γ-ray burst.

Hydrothermal venting and mineralization in the crater of Kick'em Jenny submarine volcano, Grenada (Lesser Antilles)

NASA Astrophysics Data System (ADS)

Carey, Steven; Olsen, Rene; Bell, Katherine L. C.; Ballard, Robert; Dondin, Frederic; Roman, Chris; Smart, Clara; Lilley, Marvin; Lupton, John; Seibel, Brad; Cornell, Winton; Moyer, Craig

2016-03-01

Kick'em Jenny is a frequently erupting, shallow submarine volcano located 7.5 km off the northern coast of Grenada in the Lesser Antilles subduction zone. Focused and diffuse hydrothermal venting is taking place mainly within a small (˜70 × 110 m) depression within the 300 m diameter crater of the volcano at depths of about 265 m. Much of the crater is blanketed with a layer of fine-grained tephra that has undergone hydrothermal alteration. Clear fluids and gas are being discharged near the center of the depression from mound-like vents at a maximum temperature of 180°C. The gas consists of 93-96% CO2 with trace amounts of methane and hydrogen. Gas flux measurements of individual bubble streams range from 10 to 100 kg of CO2 per day. Diffuse venting with temperatures 5-35°C above ambient occurs throughout the depression and over large areas of the main crater. These zones are colonized by reddish-yellow bacteria with the production of Fe-oxyhydroxides as surface coatings, fragile spires up to several meters in height, and elongated mounds up to tens of centimeters thick. A high-resolution photomosaic of the inner crater depression shows fluid flow patterns descending the sides of the depression toward the crater floor. We suggest that the negatively buoyant fluid flow is the result of phase separation of hydrothermal fluids at Kick'em Jenny generating a dense saline component that does not rise despite its elevated temperature.

Improved nearest codeword search scheme using a tighter kick-out condition

NASA Astrophysics Data System (ADS)

Hwang, Kuo-Feng; Chang, Chin-Chen

2001-09-01

Using a tighter kick-out condition as a faster approach to nearest codeword searches is proposed. The proposed scheme finds the nearest codeword that is identical to the one found using a full search. However, using our scheme, the search time is much shorter. Our scheme first establishes a tighter kick-out condition. Then, the temporal nearest codeword can be obtained from the codewords that survive the tighter condition. Finally, the temporal nearest codeword cooperatives with the query vector to constitute a better kick-out condition. In other words, more codewords can be excluded without actually computing the distances between the bypassed codewords and the query vector. Comparison to previous work are included to present the benefits of the proposed scheme in relation to search time.

Asymmetric neutrino reaction and pulsar kick in magnetized proto-neutron stars in fully relativistic framework

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

Maruyama, Tomoyuki; Kajino, Toshitaka; Yasutake, Nobutoshi

2012-11-12

We calculate neutrino scattering and absorption on the hot and dense neutron-star matter with hyperons under the strong magnetic field using a perturbative approach. We find that the absorption cross-sections show a remarkable angular dependence. Its strength is reduced in the direction parallel to the magnetic field and enhanced in the opposite direction. This asymmetric variation becomes maximally 2.2 % of entire neutrino momentum when the magnetic field is assumed as about 2 Multiplication-Sign 10{sup 17} G. Since the pulsar kick after the supernova explosion may have relationships to this asymmetry, detailed discussions about the pulsar kick and the asymmetrymore » are presented with the comparison to the observed kick velocities in a fully relativistic approach.« less

Unitary lens semiconductor device

DOEpatents

Lear, Kevin L.

1997-01-01

A unitary lens semiconductor device and method. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors.

Quantum Photonics Beyond Conventional Computing

DTIC Science & Technology

2015-07-10

polarisation using a half- wave plate (HWP), the two arms are combined by a polarising beam splitter (PBS). The resulting state is passed through the...phase-matched for Type-I SPDC, creating non -collinear degenerate horizontally polarised photon pairs at 808 nm. After converting one arm to vertical...For the case of non -interacting fermions, the transition probabilities for states under unitary evolution are governed by matrix determinants, which are

Optical π phase shift created with a single-photon pulse.

PubMed

Tiarks, Daniel; Schmidt, Steffen; Rempe, Gerhard; Dürr, Stephan

2016-04-01

A deterministic photon-photon quantum logic gate is a long-standing goal. Building such a gate becomes possible if a light pulse containing only one photon imprints a phase shift of π onto another light field. We experimentally demonstrate the generation of such a π phase shift with a single-photon pulse. A first light pulse containing less than one photon on average is stored in an atomic gas. Rydberg blockade combined with electromagnetically induced transparency creates a phase shift for a second light pulse, which propagates through the medium. We measure the π phase shift of the second pulse when we postselect the data upon the detection of a retrieved photon from the first pulse. This demonstrates a crucial step toward a photon-photon gate and offers a variety of applications in the field of quantum information processing.

Insights on volcanic behaviour from the 2015 July 23-24 T-phase signals generated by eruptions at Kick-'em-Jenny Submarine Volcano, Grenada, Lesser Antilles

NASA Astrophysics Data System (ADS)

Dondin, F. J. Y.; Latchman, J. L.; Robertson, R. E. A.; Lynch, L.; Stewart, R.; Smith, P.; Ramsingh, C.; Nath, N.; Ramsingh, H.; Ash, C.

2015-12-01

Kick-'em-Jenny volcano (KeJ) is the only known active submarine volcano in the Lesser Antilles Arc. Since 1939, the year it revealed itself, and until the volcano-seismic unrest of 2015 July 11-25 , the volcano has erupted 12 times. Only two eruptions breached the surface: 1939, 1974. The volcano has an average eruption cycle of about 10-11 years. Excluding the Montserrat, Soufrière Hills, KeJ is the most active volcano in the Lesser Antilles arc. The University of the West Indies, Seismic Research Centre (SRC) has been monitoring KeJ since 1953. On July 23 and 24 at 1:42 am and 0:02 am local time, respectively, the SRC recorded T-phase signals , considered to have been generated by KeJ. Both signals were recorded at seismic stations in and north of Grenada: SRC seismic stations as well as the French volcano observatories in Guadeloupe and Martinique, Montserrat Volcano Observatory, and the Puerto Rico Seismic Network. These distant recordings, along with the experience of similar observations in previous eruptions, allowed the SRC to confirm that two explosive eruptions occurred in this episode at KeJ. Up to two days after the second eruption, when aerial surveillance was done, there was no evidence of activity at the surface. During the instrumental era, eruptions of the KeJ have been identified from T-phases recorded at seismic stations from Trinidad, in the south, to Puerto Rico, in the north. In the 2015 July eruption episode, the seismic station in Trinidad did not record T-phases associated with the KeJ eruptions. In this study we compare the T-phase signals of 2015 July with those recorded in KeJ eruptions up to 1974 to explore possible causative features for the T-phase recording pattern in KeJ eruptions. In particular, we investigate the potential role played by the Sound Fixing and Ranging (SOFAR) layer in influencing the absence of the T-phase on the Trinidad seismic station during this eruption.

Phase matching of high order harmonic generation using dynamic phase modulation caused by a non-collinear modulation pulse

DOEpatents

Cohen, Oren; Kapteyn, Henry C.; Mumane, Margaret M.

2010-02-16

Phase matching high harmonic generation (HHG) uses a single, long duration non-collinear modulating pulse intersecting the driving pulse. A femtosecond driving pulse is focused into an HHG medium (such as a noble gas) to cause high-harmonic generation (HHG), for example in the X-ray region of the spectrum, via electrons separating from and recombining with gas atoms. A non-collinear pulse intersects the driving pulse within the gas, and modulates the field seen by the electrons while separated from their atoms. The modulating pulse is low power and long duration, and its frequency and amplitude is chosen to improve HHG phase matching by increasing the areas of constructive interference between the driving pulse and the HHG, relative to the areas of destructive interference.

Spin-wave utilization in a quantum computer

NASA Astrophysics Data System (ADS)

Khitun, A.; Ostroumov, R.; Wang, K. L.

2001-12-01

We propose a quantum computer scheme using spin waves for quantum-information exchange. We demonstrate that spin waves in the antiferromagnetic layer grown on silicon may be used to perform single-qubit unitary transformations together with two-qubit operations during the cycle of computation. The most attractive feature of the proposed scheme is the possibility of random access to any qubit and, consequently, the ability to recognize two qubit gates between any two distant qubits. Also, spin waves allow us to eliminate the use of a strong external magnetic field and microwave pulses. By estimate, the proposed scheme has as high as 104 ratio between quantum system coherence time and the time of a single computational step.

Precision digital pulse phase generator

DOEpatents

McEwan, T.E.

1996-10-08

A timing generator comprises a crystal oscillator connected to provide an output reference pulse. A resistor-capacitor combination is connected to provide a variable-delay output pulse from an input connected to the crystal oscillator. A phase monitor is connected to provide duty-cycle representations of the reference and variable-delay output pulse phase. An operational amplifier drives a control voltage to the resistor-capacitor combination according to currents integrated from the phase monitor and injected into summing junctions. A digital-to-analog converter injects a control current into the summing junctions according to an input digital control code. A servo equilibrium results that provides a phase delay of the variable-delay output pulse to the output reference pulse that linearly depends on the input digital control code. 2 figs.

Precision digital pulse phase generator

DOEpatents

McEwan, Thomas E.

1996-01-01

A timing generator comprises a crystal oscillator connected to provide an output reference pulse. A resistor-capacitor combination is connected to provide a variable-delay output pulse from an input connected to the crystal oscillator. A phase monitor is connected to provide duty-cycle representations of the reference and variable-delay output pulse phase. An operational amplifier drives a control voltage to the resistor-capacitor combination according to currents integrated from the phase monitor and injected into summing junctions. A digital-to-analog converter injects a control current into the summing junctions according to an input digital control code. A servo equilibrium results that provides a phase delay of the variable-delay output pulse to the output reference pulse that linearly depends on the input digital control code.

Multi-delay, phase coherent pulse pair generation for precision Ramsey-frequency comb spectroscopy.

PubMed

Morgenweg, J; Eikema, K S E

2013-03-11

We demonstrate the generation of phase-stable mJ-pulse pairs at programmable inter-pulse delays up to hundreds of nanoseconds. A detailed investigation of potential sources for phase shifts during the parametric amplification of the selected pulses from a Ti:Sapphire frequency comb is presented, both numerically and experimentally. It is shown that within the statistical error of the phase measurement of 10 mrad, there is no dependence of the differential phase shift over the investigated inter-pulse delay range of more than 300 ns. In combination with nonlinear upconversion of the amplified pulses, the presented system will potentially enable short wavelength (<100 nm), multi-transition Ramsey-frequency comb spectroscopy at the kHz-level.

Neutrino trigger of the magnetorotational mechanism of a natal-pulsar kick

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

Kuznetsov, A. V., E-mail: avkuzn@uniyar.ac.ru; Mikheev, N. V., E-mail: mikheev@uniyar.ac.ru

2013-10-15

A mechanism generating a natal-neutron-star kick and involving only standard neutrinos is discussed. In this mechanism, the neutrino effect on the plasma of the supernova-core envelope in a magnetorotational explosion accompanied by the generation of a strong toroidal magnetic field leads to a redistribution of the magnetic field B in the 'upper' and 'lower' hemispheres of the supernova-core envelope. The emerging asymmetry of the magnetic-field pressure may generate a natal-pulsar kick.

Patello-femoral and tibio-femoral contact forces during kicking type of activity

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

Engin, A.E.; Tumer, S.T.

1996-12-31

In this paper patello-femoral and tibia-femoral contact forces during kicking type of activity is presented by means of a dynamic model of the knee joint which includes tibio-femoral and patello-femoral articulations, and the major ligaments of the joint. The model shows that the patella can be subjected to very large transient patello-femoral contact forces during a strenuous lower limb activity such as kicking even under conditions of small knee-flexion angles.

An ideal free-kick

NASA Astrophysics Data System (ADS)

De Luca, R.; Faella, O.

2017-01-01

The kinematics of a free-kick is studied. As in projectile motion, the free-kick is ideal since we assume that a point-like ball moves in the absence of air resistance. We have experienced the fortunate conjuncture of a classical mechanics lecture taught right before an important football game. These types of sports events might trigger a great deal of attention from the classroom. The idealized problem is devised in such a way that students are eager to come to the end of the whole story.

A unitary healing praxis model for women in despair.

PubMed

Cowling, W Richard

2006-04-01

The evolution of a unitary healing praxis model derived from three unitary appreciative inquiries of despair is described. Explication of unitary appreciative inquiry and how it informed and contributed to the development of the model is provided. The model is based on a conceptualization of healing as appreciating the inherent wholeness of life and provides knowledge specific to the individual lives of women in despair. The process of generative theorizing that led to the creation of the model is explicated. Unitary, appreciative, and participatory responses to despair are integrated in the model, praxis modalities are delineated, key concerns and perspectives of women in despair are addressed, and potentialities for healing are illustrated.

Instrument development and the measurement of unitary constructs.

PubMed

Carboni, J T

1992-01-01

This article initiates needed dialogue on the development of instruments to measure unitary constructs. The concept of measurement is explored and current measurement in Rogerian research is considered in light of the issues raised in the discussion. The human field - environmental field relationship is presented as the clinical practice area serving as the basis for the development of a unitary instrument that purports to measure field pattern. The instrument entitled Mutual Exploration of the Healing Human Field - Environmental Field Relationship is offered as a beginning effort in constructing an instrument that measures a unitary phenomenon. Rogerian scholars are provided with the challenge to continue the debate regarding the whole field of measurement and the development of unitary tools.

Should an increase in cerebral neurochemicals following head kicks in full contact karate influence return to play?

PubMed

Graham, M R; Pates, J; Davies, B; Cooper, S M; Bhattacharya, K; Evans, P J; Baker, J S

2015-12-01

Cerebral neurochemicals are markers of traumatic brain injury (TBI). The aim of the study was to determine whether kicks to the head (KTH) in full contact karate significantly increased serum concentrations of protein S-100B, and neurone specific enolase (NSE). Kicks to the body (KTB) were also quantified to asses muscle tissue injury. Muscle damage was assessed by analysis of serum total creatine kinase (CK). Twenty-four full contact karate practitioners were observed and filmed during actual competition and divided into two main groups post event: (1) Kicks to the head and body group (KTH): n = 12; mean ± SD; age, 30.4 ± 6.7 years; height, 1.74 ± 0.1 m; weight, 79.1 ± 2.1 kg; and (2): Kicks to the body group (KTB): n = 12; mean ± SD; age, 28.2 ± 6.5 years; height, 1.75 ± 0.1 m; weight, 79.2 ± 1.7 kg. The KTH group received direct kicks to the head, while group KTB received kicks and punches to the body. Blood samples were taken before and immediately post-combat for analysis of serum S-100B, NSE, CK and cardiac troponin. Significant increases in serum concentrations of S-100B (0.12 ± 0.17 vs. 0.37 ± 0.26, µg.L(-1)) and NSE (11.8 ± 4.1 vs. 20.2 ± 9.1 ng.mL(-1)) were encountered after combat in the KTH group and CK (123 ± 53 vs. 184 ± 103 U.L(-1)) in the KTB group (all P <0.05). Head kicks in full contact karate cause elevation of neurochemical markers associated with damaged brain tissue. The severity of injury is related to the early post-traumatic release of protein S-100B and NSE. The early kinetics and appearance post injury can reflect intracranial pathology, and suggest S-100B and NSE are extremely sensitive prognostic markers of TBI. © The Author(s) 2015.

Unitary lens semiconductor device

DOEpatents

Lear, K.L.

1997-05-27

A unitary lens semiconductor device and method are disclosed. The unitary lens semiconductor device is provided with at least one semiconductor layer having a composition varying in the growth direction for unitarily forming one or more lenses in the semiconductor layer. Unitary lens semiconductor devices may be formed as light-processing devices such as microlenses, and as light-active devices such as light-emitting diodes, photodetectors, resonant-cavity light-emitting diodes, vertical-cavity surface-emitting lasers, and resonant cavity photodetectors. 9 figs.

Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: A two-fluid hydrodynamic description

NASA Astrophysics Data System (ADS)

Hu, Hui; Zou, Peng; Liu, Xia-Ji

2018-02-01

We provide a description of the dynamic structure factor of a homogeneous unitary Fermi gas at low momentum and low frequency, based on the dissipative two-fluid hydrodynamic theory. The viscous relaxation time is estimated and is used to determine the regime where the hydrodynamic theory is applicable and to understand the nature of sound waves in the density response near the superfluid phase transition. By collecting the best knowledge on the shear viscosity and thermal conductivity known so far, we calculate the various diffusion coefficients and obtain the damping width of the (first and second) sounds. We find that the damping width of the first sound is greatly enhanced across the superfluid transition and very close to the transition the second sound might be resolved in the density response for the transferred momentum up to half of Fermi momentum. Our work is motivated by the recent measurement of the local dynamic structure factor at low momentum at Swinburne University of Technology and the ongoing experiment on sound attenuation of a homogeneous unitary Fermi gas at Massachusetts Institute of Technology. We discuss how the measurement of the velocity and damping width of the sound modes in low-momentum dynamic structure factor may lead to an improved determination of the universal superfluid density, shear viscosity, and thermal conductivity of a unitary Fermi gas.

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator.

PubMed

Nie, Yongming; Ma, Haotong; Li, Xiujian; Hu, Wenhua; Yang, Jiankun

2011-07-20

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200 mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230 fs, which is caused by the spatial-temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged. © 2011 Optical Society of America

FPGA-Based Optical Cavity Phase Stabilization for Coherent Pulse Stacking

DOE PAGES

Xu, Yilun; Wilcox, Russell; Byrd, John; ...

2017-11-20

Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy from fiber lasers. We develop a robust, scalable, and distributed digital control system with firmware and software integration for algorithms, to support the CPS application. We model CPS as a digital filter in the Z domain and implement a pulse-pattern-based cavity phase detection algorithm on an field-programmable gate array (FPGA). A two-stage (2+1 cavities) 15-pulse stacking system achieves an 11.0 peak-power enhancement factor. Each optical cavity is fed back at 1.5kHz, and stabilized at anmore » individually-prescribed round-trip phase with 0.7deg and 2.1deg rms phase errors for Stages 1 and 2, respectively. Optical cavity phase control with nanometer accuracy ensures 1.2% intensity stability of the stacked pulse over 12 h. The FPGA-based feedback control system can be scaled to large numbers of optical cavities.« less

FPGA-Based Optical Cavity Phase Stabilization for Coherent Pulse Stacking

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

Xu, Yilun; Wilcox, Russell; Byrd, John

Coherent pulse stacking (CPS) is a new time-domain coherent addition technique that stacks several optical pulses into a single output pulse, enabling high pulse energy from fiber lasers. We develop a robust, scalable, and distributed digital control system with firmware and software integration for algorithms, to support the CPS application. We model CPS as a digital filter in the Z domain and implement a pulse-pattern-based cavity phase detection algorithm on an field-programmable gate array (FPGA). A two-stage (2+1 cavities) 15-pulse stacking system achieves an 11.0 peak-power enhancement factor. Each optical cavity is fed back at 1.5kHz, and stabilized at anmore » individually-prescribed round-trip phase with 0.7deg and 2.1deg rms phase errors for Stages 1 and 2, respectively. Optical cavity phase control with nanometer accuracy ensures 1.2% intensity stability of the stacked pulse over 12 h. The FPGA-based feedback control system can be scaled to large numbers of optical cavities.« less

All-Fiber, Directly Chirped Laser Source for Chirped-Pulse-Amplification

NASA Astrophysics Data System (ADS)

Xin, Ran

Chirped-pulse-amplification (CPA) technology is widely used to produce ultra-short optical pulses (sub picosecond to femtoseconds) with high pulse energy. A chirped pulse laser source with flexible dispersion control is highly desirable as a CPA seed. This thesis presents an all-fiber, directly chirped laser source (DCLS) that produces nanosecond, linearly-chirped laser pulses at 1053 nm for seeding high energy CPA systems. DCLS produces a frequency chirp on an optical pulse through direct temporal phase modulation. DCLS provides programmable control for the temporal phase of the pulse, high pulse energy and diffraction-limited beam performance, which are beneficial for CPA systems. The DCLS concept is first described. Its key enabling technologies are identified and their experimental demonstration is presented. These include high-precision temporal phase control using an arbitrary waveform generator, multi-pass phase modulation to achieve high modulation depth, regenerative amplification in a fiber ring cavity and a negative feedback system that controls the amplifier cavity dynamics. A few technical challenges that arise from the multi-pass architecture are described and their solutions are presented, such as polarization management and gain-spectrum engineering in the DCLS fiber cavity. A DCLS has been built and its integration into a high energy OPCPA system is demonstrated. DCLS produces a 1-ns chirped pulse with a 3-nm bandwidth. The temporal phase and group delay dispersion on the DCLS output pulse is measured using temporal interferometry. The measured temporal phase has an ˜1000 rad amplitude and is close to a quadratic shape. The chirped pulse is amplified from 0.9 nJ to 76 mJ in an OPCPA system. The amplified pulse is compressed to close to its Fourier transform limit, producing an intensity autocorrelation trace with a 1.5-ps width. Direct compressed-pulse duration control by adjusting the phase modulation drive amplitude is demonstrated. Limitation to pulse compression is investigated using numerical simulation.

Energy Modeling Capabilities in ORD's Air, Climate and ...

EPA Pesticide Factsheets

Presentation to ACE Centers Kick-Off Meeting highlighting energy modeling work, capabilities and tools that are under development in ORD/NRMRL under the ACE Program. Presentation to ACE Centers Kick-Off Meeting

Gamma-Ray Bursts from Neutron Star Kicks

NASA Astrophysics Data System (ADS)

Huang, Y. F.; Dai, Z. G.; Lu, T.; Cheng, K. S.; Wu, X. F.

2003-09-01

The idea that gamma-ray bursts might be a phenomenon associated with neutron star kicks was first proposed by Dar & Plaga. Here we study this mechanism in more detail and point out that the neutron star should be a high-speed one (with proper motion larger than ~1000 km s-1). It is shown that the model agrees well with observations in many aspects, such as the energetics, the event rate, the collimation, the bimodal distribution of durations, the narrowly clustered intrinsic energy, and the association of gamma-ray bursts with supernovae and star-forming regions. We also discuss the implications of this model on the neutron star kick mechanism and suggest that the high kick speed was probably acquired as the result of the electromagnetic rocket effect of a millisecond magnetar with an off-centered magnetic dipole.

Spectral relationships between kicked Harper and on-resonance double kicked rotor operators

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

Lawton, Wayne; Mouritzen, Anders S.; Wang Jiao

2009-03-15

Kicked Harper operators and on-resonance double kicked rotor operators model quantum systems whose semiclassical limits exhibit chaotic dynamics. Recent computational studies indicate a striking resemblance between the spectra of these operators. In this paper we apply C*-algebra methods to explain this resemblance. We show that each pair of corresponding operators belongs to a common rotation C*-algebra B{sub {alpha}}, prove that their spectra are equal if {alpha} is irrational, and prove that the Hausdorff distance between their spectra converges to zero as q increases if {alpha}=p/q with p and q coprime integers. Moreover, we show that corresponding operators in B{sub {alpha}}more » are homomorphic images of mother operators in the universal rotation C*-algebra A{sub {alpha}} that are unitarily equivalent and hence have identical spectra. These results extend analogous results for almost Mathieu operators. We also utilize the C*-algebraic framework to develop efficient algorithms to compute the spectra of these mother operators for rational {alpha} and present preliminary numerical results that support the conjecture that their spectra are Cantor sets if {alpha} is irrational. This conjecture for almost Mathieu operators, called the ten Martini problem, was recently proven after intensive efforts over several decades. This proof for the almost Mathieu operators utilized transfer matrix methods, which do not exist for the kicked operators. We outline a strategy, based on a special property of loop groups of semisimple Lie groups, to prove this conjecture for the kicked operators.« less

Transverse Kick Analysis of SSR1 Due to Possible Geometrical Variations in Fabrication

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

Yakovlev, V.P.; /Fermilab; Awida, M.H.

2012-05-01

Due to fabrication tolerance, it is expected that some geometrical variations could happen to the SSR1 cavities of Project X, like small shifts in the transverse direction of the beam pipe or the spoke. It is necessary to evaluate the resultant transverse kick due to these geometrical variations, in order to make sure that they are within the limits of the correctors in the solenoids. In this paper, we report the transverse kick values for various fabrications errors and the sensitivity of the beam to these errors. Transverse kick that could happen in SSR1 cavities due to geometrical variations ofmore » the fabricated cavities from the designed geometry has been analysed and evaluated. From fabrication experience, three kinds of variations were under investigation concerning the alignment of both the beam pipe and spoke with respect to the beam axis. Simulation study has been carried out implementing these variations in the simulation model. CMM measurements of five fabricated SSR1 cavities were carried out to investigate the amount of physical misalignments of the beam pipe and spoke. Bead-pull measurements were also conducted to evaluate the transverse kick values in the fabricated cavities. Simulation and measurements are relatively in good agreement. Maximum kick in the fabricated cavities is within 154 keV that would induce about 1.12 mrad beam deviation, which could be definitely corrected with the 10 mrad specified correctors of Project X.« less

Asymmetric predictability and cognitive competition in football penalty shootouts.

PubMed

Misirlisoy, Erman; Haggard, Patrick

2014-08-18

Sports provide powerful demonstrations of cognitive strategies underlying competitive behavior. Penalty shootouts in football (soccer) involve direct competition between elite players and absorb the attention of millions. The penalty shootout between Germany and England in the 1990 World Cup semifinal was viewed by an estimated 46.49% of the UK population. In a penalty shootout, a goalkeeper must defend their goal without teammate assistance while an opposing series of kickers aim to kick the ball past them into the net. As in many sports, the ball during a penalty kick often approaches too quickly for the goalkeeper to react to its direction of motion; instead, the goalkeeper must guess the likely direction of the kick, and dive in anticipation, if they are to have a chance of saving the shot. We examined all 361 kicks from the 37 penalty shootouts that occurred in World Cup and Euro Cup matches over a 36-year period from 1976 to 2012 and show that goalkeepers displayed a clear sequential bias. Following repeated kicks in the same direction, goalkeepers became increasingly likely to dive in the opposite direction on the next kick. Surprisingly, kickers failed to exploit these goalkeeper biases. Our findings highlight the importance of monitoring and predicting sequential behavior in real-world competition. Penalty shootouts pit one goalkeeper against several kickers in rapid succession. Asymmetries in the cognitive capacities of an individual versus a group could produce significant advantages over opponents. Copyright © 2014 Elsevier Ltd. All rights reserved.

Investigation of kinematics of knuckling shot in soccer

NASA Astrophysics Data System (ADS)

Asai, T.; Hong, S.

2017-02-01

In this study, we use four high-speed video cameras to investigate the swing characteristics of the kicking leg while delivering the knuckling shot in soccer. We attempt to elucidate the impact process of the kicking foot at the instant of its impact with the ball and the technical mechanisms of the knuckling shot via comparison of its curved motion with that of the straight and curved shots. Two high-speed cameras (Fastcam, Photron Inc., Tokyo, Japan; 1000 fps, 1024 × 1024 pixels) are set up 2 m away from the site of impact with a line of sight perpendicular to the kicking-leg side. In addition, two semi-high-speed cameras (EX-F1, Casio Computer Co., Ltd., Tokyo, Japan; 300 fps; 720 × 480 pixels) are positioned, one at the rear and the other on the kicking-leg side, to capture the kicking motion. We observe that the ankle joint at impact in the knuckling shot flexes in an approximate L-shape in a manner similar to the joint flexing for the curve shot. The hip's external rotation torque in the knuckling shot is greater than those of other shots, which suggests the tendency of the kicker to push the heel forward and impact with the inside of the foot. The angle of attack in the knuckling shot is smaller than that in other shots, and we speculate that this small attack angle is a factor in soccer kicks which generate shots with smaller rotational frequencies of the ball.

Separability and Entanglement in the Hilbert Space Reference Frames Related Through the Generic Unitary Transform for Four Level System

NASA Astrophysics Data System (ADS)

Man'ko, V. I.; Markovich, L. A.

2018-02-01

Quantum correlations in the state of four-level atom are investigated by using generic unitary transforms of the classical (diagonal) density matrix. Partial cases of pure state, X-state, Werner state are studied in details. The geometrical meaning of unitary Hilbert reference-frame rotations generating entanglement in the initially separable state is discussed. Characteristics of the entanglement in terms of concurrence, entropy and negativity are obtained as functions of the unitary matrix rotating the reference frame.

Local unitary equivalence of quantum states and simultaneous orthogonal equivalence

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

Jing, Naihuan, E-mail: jing@ncsu.edu; Yang, Min; Zhao, Hui, E-mail: zhaohui@bjut.edu.cn

2016-06-15

The correspondence between local unitary equivalence of bipartite quantum states and simultaneous orthogonal equivalence is thoroughly investigated and strengthened. It is proved that local unitary equivalence can be studied through simultaneous similarity under projective orthogonal transformations, and four parametrization independent algorithms are proposed to judge when two density matrices on ℂ{sup d{sub 1}} ⊗ ℂ{sup d{sub 2}} are locally unitary equivalent in connection with trace identities, Kronecker pencils, Albert determinants and Smith normal forms.

Entanglement quantification by local unitary operations

NASA Astrophysics Data System (ADS)

Monras, A.; Adesso, G.; Giampaolo, S. M.; Gualdi, G.; Davies, G. B.; Illuminati, F.

2011-07-01

Invariance under local unitary operations is a fundamental property that must be obeyed by every proper measure of quantum entanglement. However, this is not the only aspect of entanglement theory where local unitary operations play a relevant role. In the present work we show that the application of suitable local unitary operations defines a family of bipartite entanglement monotones, collectively referred to as “mirror entanglement.” They are constructed by first considering the (squared) Hilbert-Schmidt distance of the state from the set of states obtained by applying to it a given local unitary operator. To the action of each different local unitary operator there corresponds a different distance. We then minimize these distances over the sets of local unitary operations with different spectra, obtaining an entire family of different entanglement monotones. We show that these mirror-entanglement monotones are organized in a hierarchical structure, and we establish the conditions that need to be imposed on the spectrum of a local unitary operator for the associated mirror entanglement to be faithful, i.e., to vanish in and only in separable pure states. We analyze in detail the properties of one particularly relevant member of the family, the “stellar mirror entanglement” associated with the traceless local unitary operations with nondegenerate spectra and equispaced eigenvalues in the complex plane. This particular measure generalizes the original analysis of S. M. Giampaolo and F. Illuminati [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.76.042301 76, 042301 (2007)], valid for qubits and qutrits. We prove that the stellar entanglement is a faithful bipartite entanglement monotone in any dimension and that it is bounded from below by a function proportional to the linear entropy and from above by the linear entropy itself, coinciding with it in two- and three-dimensional spaces.

Entanglement quantification by local unitary operations

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

Monras, A.; Giampaolo, S. M.; Gualdi, G.

2011-07-15

Invariance under local unitary operations is a fundamental property that must be obeyed by every proper measure of quantum entanglement. However, this is not the only aspect of entanglement theory where local unitary operations play a relevant role. In the present work we show that the application of suitable local unitary operations defines a family of bipartite entanglement monotones, collectively referred to as ''mirror entanglement.'' They are constructed by first considering the (squared) Hilbert-Schmidt distance of the state from the set of states obtained by applying to it a given local unitary operator. To the action of each different localmore » unitary operator there corresponds a different distance. We then minimize these distances over the sets of local unitary operations with different spectra, obtaining an entire family of different entanglement monotones. We show that these mirror-entanglement monotones are organized in a hierarchical structure, and we establish the conditions that need to be imposed on the spectrum of a local unitary operator for the associated mirror entanglement to be faithful, i.e., to vanish in and only in separable pure states. We analyze in detail the properties of one particularly relevant member of the family, the ''stellar mirror entanglement'' associated with the traceless local unitary operations with nondegenerate spectra and equispaced eigenvalues in the complex plane. This particular measure generalizes the original analysis of S. M. Giampaolo and F. Illuminati [Phys. Rev. A 76, 042301 (2007)], valid for qubits and qutrits. We prove that the stellar entanglement is a faithful bipartite entanglement monotone in any dimension and that it is bounded from below by a function proportional to the linear entropy and from above by the linear entropy itself, coinciding with it in two- and three-dimensional spaces.« less

The Orbit of X Persei and Its Neutron Star Companion

NASA Astrophysics Data System (ADS)

Delgado-Martí, Hugo; Levine, Alan M.; Pfahl, Eric; Rappaport, Saul A.

2001-01-01

We have observed the Be/X-ray pulsar binary system X Per/4U 0352+30 on 61 occasions spanning an interval of 600 days with the PCA instrument on board the Rossi X-Ray Timing Explorer (RXTE). Pulse timing analyses of the 837 s pulsations yield strong evidence for the presence of orbital Doppler delays. We confirm the Doppler delays by using measurements made with the All Sky Monitor (ASM) on RXTE. We infer that the orbit is characterized by a period Porb=250 days, a projected semimajor axis of the neutron star axsini=454 lt-s, a mass function f(M)=1.61 Msolar, and a modest eccentricity e=0.11. The measured orbital parameters, together with the known properties of the classical Be star X Per, imply a semimajor axis a=1.8-2.2 AU and an orbital inclination i~26deg-33deg. We discuss the formation of the system in the context of the standard evolutionary scenario for Be/X-ray binaries. We find that the system most likely formed from a pair of massive progenitor stars and probably involved a quasi-stable and nearly conservative transfer of mass from the primary to the secondary. We find that the He star remnant of the primary most likely had a mass <~6 Msolar after mass transfer. If the supernova explosion was completely symmetric, then the present orbital eccentricity indicates that <~4 Msolar was ejected from the binary. If, on the other hand, the neutron star received at birth a ``kick'' of the type often inferred from the velocity distribution of isolated radio pulsars, then the resultant orbital eccentricity would likely have been substantially larger than 0.11. We have carried out a Monte Carlo study of the effects of such natal kicks and find that there is less than a 1% probability of a system like that of X Per forming with an orbital eccentricity e<~0.11. We speculate that there may be a substantial population of neutron stars formed with little or no kick. Finally, we discuss the connected topics of the wide orbit and accretion by the neutron star from a stellar wind.

Isotropic scalar image visualization of vector differential image data using the inverse Riesz transform.

PubMed

Larkin, Kieran G; Fletcher, Peter A

2014-03-01

X-ray Talbot moiré interferometers can now simultaneously generate two differential phase images of a specimen. The conventional approach to integrating differential phase is unstable and often leads to images with loss of visible detail. We propose a new reconstruction method based on the inverse Riesz transform. The Riesz approach is stable and the final image retains visibility of high resolution detail without directional bias. The outline Riesz theory is developed and an experimentally acquired X-ray differential phase data set is presented for qualitative visual appraisal. The inverse Riesz phase image is compared with two alternatives: the integrated (quantitative) phase and the modulus of the gradient of the phase. The inverse Riesz transform has the computational advantages of a unitary linear operator, and is implemented directly as a complex multiplication in the Fourier domain also known as the spiral phase transform.

Isotropic scalar image visualization of vector differential image data using the inverse Riesz transform

PubMed Central

Larkin, Kieran G.; Fletcher, Peter A.

2014-01-01

X-ray Talbot moiré interferometers can now simultaneously generate two differential phase images of a specimen. The conventional approach to integrating differential phase is unstable and often leads to images with loss of visible detail. We propose a new reconstruction method based on the inverse Riesz transform. The Riesz approach is stable and the final image retains visibility of high resolution detail without directional bias. The outline Riesz theory is developed and an experimentally acquired X-ray differential phase data set is presented for qualitative visual appraisal. The inverse Riesz phase image is compared with two alternatives: the integrated (quantitative) phase and the modulus of the gradient of the phase. The inverse Riesz transform has the computational advantages of a unitary linear operator, and is implemented directly as a complex multiplication in the Fourier domain also known as the spiral phase transform. PMID:24688823

Scheme for implementing 1 → M symmetric economical phase-covariant telecloning based on quantum logic network

NASA Astrophysics Data System (ADS)

Zhou, Yan-Hui; Wang, Lei

2012-04-01

The quantum logic network to implement 1 → M symmetric economical phase-covariant telecloning is presented. The scheme includes two parts: the first part is used to create the telecloning channel and the second part to teleport the input state. The telecloning channel which works without ancilla is constructed by two kinds of elementary unitary transformations, single-qubit rotation and multiple-qubit controlled operation. The probability of success is 50%, which is the same with the scheme in [Meng, F.Y.; Zhu, A.D. J. Mod. Opt. 2009, 56, 1255-1259].

Ground-state fidelity and bipartite entanglement in the Bose-Hubbard model.

PubMed

Buonsante, P; Vezzani, A

2007-03-16

We analyze the quantum phase transition in the Bose-Hubbard model borrowing two tools from quantum-information theory, i.e., the ground-state fidelity and entanglement measures. We consider systems at unitary filling comprising up to 50 sites and show for the first time that a finite-size scaling analysis of these quantities provides excellent estimates for the quantum critical point. We conclude that fidelity is particularly suited for revealing a quantum phase transition and pinning down the critical point thereof, while the success of entanglement measures depends on the mechanisms governing the transition.

Quantum walks with an anisotropic coin I: spectral theory

NASA Astrophysics Data System (ADS)

Richard, S.; Suzuki, A.; Tiedra de Aldecoa, R.

2018-02-01

We perform the spectral analysis of the evolution operator U of quantum walks with an anisotropic coin, which include one-defect models, two-phase quantum walks, and topological phase quantum walks as special cases. In particular, we determine the essential spectrum of U, we show the existence of locally U-smooth operators, we prove the discreteness of the eigenvalues of U outside the thresholds, and we prove the absence of singular continuous spectrum for U. Our analysis is based on new commutator methods for unitary operators in a two-Hilbert spaces setting, which are of independent interest.

Quantum ratchet effect in a time non-uniform double-kicked model

NASA Astrophysics Data System (ADS)

Chen, Lei; Wang, Zhen-Yu; Hui, Wu; Chu, Cheng-Yu; Chai, Ji-Min; Xiao, Jin; Zhao, Yu; Ma, Jin-Xiang

2017-07-01

The quantum ratchet effect means that the directed transport emerges in a quantum system without a net force. The delta-kicked model is a quantum Hamiltonian model for the quantum ratchet effect. This paper investigates the quantum ratchet effect based on a time non-uniform double-kicked model, in which two flashing potentials alternately act on a particle with a homogeneous initial state of zero momentum, while the intervals between adjacent actions are not equal. The evolution equation of the state of the particle is derived from its Schrödinger equation, and the numerical method to solve the evolution equation is pointed out. The results show that quantum resonances can induce the ratchet effect in this time non-uniform double-kicked model under certain conditions; some quantum resonances, which cannot induce the ratchet effect in previous models, can induce the ratchet effect in this model, and the strengths of the ratchet effect in this model are stronger than those in previous models under certain conditions. These results enrich people’s understanding of the delta-kicked model, and provides a new optional scheme to control the quantum transport of cold atoms in experiment.

Getting a Kick Out of Numerical Relativity

NASA Technical Reports Server (NTRS)

Baker, John G.; Centrella, Joan; Dale, Choi; Koppitz, Michael; vanMeter, James R.; Miller, M. Coleman

2005-01-01

Recent developments in numerical relativity have made it possible to follow reliably the coalescence of two black holes from near the innermost stable circular orbit to final ringdown. This opens up a wide variety of exciting astrophysical applications of these simulations. Chief among these is the net kick received when two unequal mass or spinning black holes merge. The magnitude of this kick has bearing on the production and growth of supermassive black holes during the epoch of structure formation; and on the retention of black holes in stellar clusters. Here we report the first accurate numerical calculation of this kick, for two nonspinning black holes in a 1.5:1 mass ratio, which is expected based on analytic considerations to give a significant fraction of the maximum possible recoil. Our estimated kick is 10(exp 5) km/s with an error of less than 10%. This is intermediate between the estimates from two recent post-Newtonian analyses and suggests that at redshifts z greater than or approx. equal to 10, halos with masses less than or approx. equal to 10(exp 9) Solar Mass will have difficulty retaining coalesced black holes after major mergers.

Floquet states of a kicked particle in a singular potential: Exponential and power-law profiles

NASA Astrophysics Data System (ADS)

Paul, Sanku; Santhanam, M. S.

2018-03-01

It is well known that, in the chaotic regime, all the Floquet states of kicked rotor system display an exponential profile resulting from dynamical localization. If the kicked rotor is placed in an additional stationary infinite potential well, its Floquet states display power-law profile. It has also been suggested in general that the Floquet states of periodically kicked systems with singularities in the potential would have power-law profile. In this work, we study the Floquet states of a kicked particle in finite potential barrier. By varying the height of finite potential barrier, the nature of transition in the Floquet state from exponential to power-law decay profile is studied. We map this system to a tight-binding model and show that the nature of decay profile depends on energy band spanned by the Floquet states (in unperturbed basis) relative to the potential height. This property can also be inferred from the statistics of Floquet eigenvalues and eigenvectors. This leads to an unusual scenario in which the level spacing distribution, as a window in to the spectral correlations, is not a unique characteristic for the entire system.

Carrier-phase control among subharmonic pulses in a femtosecond optical parametric oscillator.

PubMed

Kobayashi, Y; Torizuka, K

2001-08-15

We have generated femtosecond subharmonic pulses by using an optical parametric oscillator. The optical frequencies of the idler and the signal are one third and two thirds, respectively, of the optical frequency of the pump pulse. The carrier phase of the signal pulse relative to that of the pump pulse was locked by electronic feedback. The carrier-envelope phase slip frequency of the signal pulse relative to that of the pump was locked to F/6 , where F is defined as the repetition frequency.

A comparison of models of the isometric force of locust skeletal muscle in response to pulse train inputs.

PubMed

Wilson, Emma; Rustighi, Emiliano; Newland, Philip L; Mace, Brian R

2012-03-01

Muscle models are an important tool in the development of new rehabilitation and diagnostic techniques. Many models have been proposed in the past, but little work has been done on comparing the performance of models. In this paper, seven models that describe the isometric force response to pulse train inputs are investigated. Five of the models are from the literature while two new models are also presented. Models are compared in terms of their ability to fit to isometric force data, using Akaike's and Bayesian information criteria and by examining the ability of each model to describe the underlying behaviour in response to individual pulses. Experimental data were collected by stimulating the locust extensor tibia muscle and measuring the force generated at the tibia. Parameters in each model were estimated by minimising the error between the modelled and actual force response for a set of training data. A separate set of test data, which included physiological kick-type data, was used to assess the models. It was found that a linear model performed the worst whereas a new model was found to perform the best. The parameter sensitivity of this new model was investigated using a one-at-a-time approach, and it found that the force response is not particularly sensitive to changes in any parameter.

Duality quantum algorithm efficiently simulates open quantum systems

PubMed Central

Wei, Shi-Jie; Ruan, Dong; Long, Gui-Lu

2016-01-01

Because of inevitable coupling with the environment, nearly all practical quantum systems are open system, where the evolution is not necessarily unitary. In this paper, we propose a duality quantum algorithm for simulating Hamiltonian evolution of an open quantum system. In contrast to unitary evolution in a usual quantum computer, the evolution operator in a duality quantum computer is a linear combination of unitary operators. In this duality quantum algorithm, the time evolution of the open quantum system is realized by using Kraus operators which is naturally implemented in duality quantum computer. This duality quantum algorithm has two distinct advantages compared to existing quantum simulation algorithms with unitary evolution operations. Firstly, the query complexity of the algorithm is O(d3) in contrast to O(d4) in existing unitary simulation algorithm, where d is the dimension of the open quantum system. Secondly, By using a truncated Taylor series of the evolution operators, this duality quantum algorithm provides an exponential improvement in precision compared with previous unitary simulation algorithm. PMID:27464855

Light-Induced resetting of the circadian pacemaker: quantitative analysis of transient versus steady-state phase shifts.

PubMed

Watanabe, K; Deboer, T; Meijer, J H

2001-12-01

The suprachiasmatic nuclei of the hypothalamus contain the major circadian pacemaker in mammals, driving circadian rhythms in behavioral and physiological functions. This circadian pacemaker's responsiveness to light allows synchronization to the light-dark cycle. Phase shifting by light often involves several transient cycles in which the behavioral activity rhythm gradually shifts to its steady-state position. In this article, the authors investigate in Syrian hamsters whether a phase-advancing light pulse results in immediate shifts of the PRC at the next circadian cycle. In a first series of experiments, the authors aimed a light pulse at CT 19 to induce a phase advance. It appeared that the steady-state phase advances were highly correlated with activity onset in the first and second transient cycle. This enabled them to make a reliable estimate of the steady-state phase shift induced by a phase-advancing light pulse on the basis of activity onset in the first transient cycle. In the next series of experiments, they presented a light pulse at CT 19, which was followed by a second light pulse aimed at the delay zone of the PRC on the next circadian cycle. The immediate and steady-state phase delays induced by the second light pulse were compared with data from a third experiment in which animals received a phase-delaying light pulse only. The authors observed that the waveform of the phase-delay part of the PRC (CT 12-16) obtained in Experiment 2 was virtually identical to the phase-delay part of the PRC for a single light pulse (obtained in Experiment 3). This finding allowed for a quantitative assessment of the data. The analysis indicates that the delay part of the PRC-between CT 12 and CT 16-is rapidly reset following a light pulse at CT 19. These findings complement earlier findings in the hamster showing that after a light pulse at CT 19, the phase-advancing part of the PRC is immediately shifted. Together, the data indicate that the basis for phase advancing involves rapid resetting of both advance and delay components of the PRC.

Spectral Characteristics of the Unitary Critical Almost-Mathieu Operator

NASA Astrophysics Data System (ADS)

Fillman, Jake; Ong, Darren C.; Zhang, Zhenghe

2017-04-01

We discuss spectral characteristics of a one-dimensional quantum walk whose coins are distributed quasi-periodically. The unitary update rule of this quantum walk shares many spectral characteristics with the critical Almost-Mathieu Operator; however, it possesses a feature not present in the Almost-Mathieu Operator, namely singularity of the associated cocycles (this feature is, however, present in the so-called Extended Harper's Model). We show that this operator has empty absolutely continuous spectrum and that the Lyapunov exponent vanishes on the spectrum; hence, this model exhibits Cantor spectrum of zero Lebesgue measure for all irrational frequencies and arbitrary phase, which in physics is known as Hofstadter's butterfly. In fact, we will show something stronger, namely, that all spectral parameters in the spectrum are of critical type, in the language of Avila's global theory of analytic quasiperiodic cocycles. We further prove that it has empty point spectrum for each irrational frequency and away from a frequency-dependent set of phases having Lebesgue measure zero. The key ingredients in our proofs are an adaptation of Avila's Global Theory to the present setting, self-duality via the Fourier transform, and a Johnson-type theorem for singular dynamically defined CMV matrices which characterizes their spectra as the set of spectral parameters at which the associated cocycles fail to admit a dominated splitting.

Phase and period responses of the circadian system of mice (Mus musculus) to light stimuli of different duration.

PubMed

Comas, M; Beersma, D G M; Spoelstra, K; Daan, S

2006-10-01

To understand entrainment of circadian systems to different photoperiods in nature, it is important to know the effects of single light pulses of different durations on the free-running system. The authors studied the phase and period responses of laboratory mice (C57BL6J//OlaHsd) to single light pulses of 7 different durations (1, 3, 4, 6, 9, 12, and 18 h) given once per 11 days in otherwise constant darkness. Light-pulse duration affected both amplitude and shape of the phase response curve. Nine-hour light pulses yielded the maximal amplitude PRC. As in other systems, the circadian period slightly lengthened following delays and shortened following advances. The authors aimed to understand how different parts of the light signal contribute to the eventual phase shift. When PRCs were plotted using the onset, midpoint, and end of the pulse as a phase reference, they corresponded best with each other when using the mid-pulse. Using a simple phase-only model, the authors explored the possibility that light affects oscillator velocity strongly in the 1st hour and at reduced strength in later hours of the pulse due to photoreceptor adaptation. They fitted models based on the 1-h PRC to the data for all light pulses. The best overall correspondence between PRCs was obtained when the effect of light during all hours after the first was reduced by a factor of 0.22 relative to the 1st hour. For the predicted PRCs, the light action centered on average at 38% of the light pulse. This is close to the reference phase yielding best correspondence at 36% of the pulses. The result is thus compatible with an initial major contribution of the onset of the light pulse followed by a reduced effect of light responsible for the differences between PRCs for different duration pulses. The authors suggest that the mid-pulse is a better phase reference than lights-on to plot and compare PRCs of different light-pulse durations.

Hypercompact Stellar Systems Around Recoiling Supermassive Black Holes

NASA Astrophysics Data System (ADS)

Merritt, David; Schnittman, Jeremy D.; Komossa, S.

2009-07-01

A supermassive black hole ejected from the center of a galaxy by gravitational-wave recoil carries a retinue of bound stars—a "hypercompact stellar system" (HCSS). The numbers and properties of HCSSs contain information about the merger histories of galaxies, the late evolution of binary black holes, and the distribution of gravitational-wave kicks. We relate the structural properties (size, mass, density profile) of HCSSs to the properties of their host galaxies and to the size of the kick in two regimes: collisional (M BH lsim 107 M sun), i.e., short nuclear relaxation times, and collisionless (M BH gsim 107 M sun), i.e., long nuclear relaxation times. HCSSs are expected to be similar in size and luminosity to globular clusters, but in extreme cases (large galaxies, kicks just above escape velocity) their stellar mass can approach that of ultracompact dwarf galaxies. However, they differ from all other classes of compact stellar system in having very high internal velocities. We show that the kick velocity is encoded in the velocity dispersion of the bound stars. Given a large enough sample of HCSSs, the distribution of gravitational-wave kicks can therefore be empirically determined. We combine a hierarchical merger algorithm with stellar population models to compute the rate of production of HCSSs over time and the probability of observing HCSSs in the local universe as a function of their apparent magnitude, color, size, and velocity dispersion, under two different assumptions about the star formation history prior to the kick. We predict that ~102 HCSSs should be detectable within 2 Mpc of the center of the Virgo cluster, and that many of these should be bright enough that their kick velocities (i.e., velocity dispersions) could be measured with reasonable exposure times. We discuss other strategies for detecting HCSSs and speculate on some exotic manifestations.

Optimum Projection Angle for Attaining Maximum Distance in a Soccer Punt Kick

PubMed Central

Linthorne, Nicholas P.; Patel, Dipesh S.

2011-01-01

To produce the greatest horizontal distance in a punt kick the ball must be projected at an appropriate angle. Here, we investigated the optimum projection angle that maximises the distance attained in a punt kick by a soccer goalkeeper. Two male players performed many maximum-effort kicks using projection angles of between 10° and 90°. The kicks were recorded by a video camera at 100 Hz and a 2 D biomechanical analysis was conducted to obtain measures of the projection velocity, projection angle, projection height, ball spin rate, and foot velocity at impact. The player’s optimum projection angle was calculated by substituting mathematical equations for the relationships between the projection variables into the equations for the aerodynamic flight of a soccer ball. The calculated optimum projection angles were in agreement with the player’s preferred projection angles (40° and 44°). In projectile sports even a small dependence of projection velocity on projection angle is sufficient to produce a substantial shift in the optimum projection angle away from 45°. In the punt kicks studied here, the optimum projection angle was close to 45° because the projection velocity of the ball remained almost constant across all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle and so the optimum projection angle is well below 45°. Key points The optimum projection angle that maximizes the distance of a punt kick by a soccer goalkeeper is about 45°. The optimum projection angle is close to 45° because the projection velocity of the ball is almost the same at all projection angles. This result is in contrast to throwing and jumping for maximum distance, where the optimum projection angle is well below 45° because the projection velocity the athlete is able to achieve decreases substantially with increasing projection angle. PMID:24149315

A biomechanical analysis of the roundhouse kicking technique of expert practitioners: A comparison between the martial arts disciplines of Muay Thai, Karate, and Taekwondo

PubMed Central

2017-01-01

The purpose of this study was first, to determine whether there were differences in the roundhouse kicking leg kinematics performed by highly skilled Muay Thai, Karate and Taekwondo practitioners (n = 8 per group). Next, analysis aimed to identify the kinematic determinants of effective roundhouse kicking performance. Three-dimensional (3D) lower limb kinematics were recorded using a nine camera infra-red motion capture system (500 Hz) during three maximal roundhouse kicks. Impact forces were recorded using a strain gauge (1000 Hz) attached to a kicking pad positioned at the height of each participant’s mastoid process. Results showed that linear foot velocity at impact was moderately correlated with relative impact force (r = 0.66, P = 0.001). Discipline specific analyses of the temporal data indicated that the Muay Thai group had a shorter execution time (1.02 ± 0.15 s) than Taekwondo (1.54 ± 0.52 s, P = 0.028). Analysis of lower limb kinematic data indicated that both Karate (-947 ± 94 deg/s, P = 0.010) and Taekwondo (-943 ± 106 deg/s, P = 0.011) practitioners had faster knee extension velocities than the Muay Thai group (-706 ± 200 deg/s). Conversely, the Muay Thai practitioners (1.24 ± 0.15 m/s) had greater vertical centre of mass movement than both Karate (0.78 ± 0.24 m/s, P = 0.001) and Taekwondo groups (0.93 ± 0.19 m/s, P = 0.02). Our findings show that several fundamental movement patterns were common to the roundhouse kicking techniques across the Muay Thai, Karate, and Taekwondo disciplines. Effective roundhouse kicking performance was characterized by rapid pelvic axial rotation, hip abduction, hip flexion and knee extension velocities, combined with rapid movements of the COM towards the target. PMID:28841670

A biomechanical analysis of the roundhouse kicking technique of expert practitioners: A comparison between the martial arts disciplines of Muay Thai, Karate, and Taekwondo.

PubMed

Gavagan, Colin J; Sayers, Mark G L

2017-01-01

The purpose of this study was first, to determine whether there were differences in the roundhouse kicking leg kinematics performed by highly skilled Muay Thai, Karate and Taekwondo practitioners (n = 8 per group). Next, analysis aimed to identify the kinematic determinants of effective roundhouse kicking performance. Three-dimensional (3D) lower limb kinematics were recorded using a nine camera infra-red motion capture system (500 Hz) during three maximal roundhouse kicks. Impact forces were recorded using a strain gauge (1000 Hz) attached to a kicking pad positioned at the height of each participant's mastoid process. Results showed that linear foot velocity at impact was moderately correlated with relative impact force (r = 0.66, P = 0.001). Discipline specific analyses of the temporal data indicated that the Muay Thai group had a shorter execution time (1.02 ± 0.15 s) than Taekwondo (1.54 ± 0.52 s, P = 0.028). Analysis of lower limb kinematic data indicated that both Karate (-947 ± 94 deg/s, P = 0.010) and Taekwondo (-943 ± 106 deg/s, P = 0.011) practitioners had faster knee extension velocities than the Muay Thai group (-706 ± 200 deg/s). Conversely, the Muay Thai practitioners (1.24 ± 0.15 m/s) had greater vertical centre of mass movement than both Karate (0.78 ± 0.24 m/s, P = 0.001) and Taekwondo groups (0.93 ± 0.19 m/s, P = 0.02). Our findings show that several fundamental movement patterns were common to the roundhouse kicking techniques across the Muay Thai, Karate, and Taekwondo disciplines. Effective roundhouse kicking performance was characterized by rapid pelvic axial rotation, hip abduction, hip flexion and knee extension velocities, combined with rapid movements of the COM towards the target.

The canonical quantization of chaotic maps on the torus

NASA Astrophysics Data System (ADS)

Rubin, Ron Shai

In this thesis, a quantization method for classical maps on the torus is presented. The quantum algebra of observables is defined as the quantization of measurable functions on the torus with generators exp (2/pi ix) and exp (2/pi ip). The Hilbert space we use remains the infinite-dimensional L2/ (/IR, dx). The dynamics is given by a unitary quantum propagator such that as /hbar /to 0, the classical dynamics is returned. We construct such a quantization for the Kronecker map, the cat map, the baker's map, the kick map, and the Harper map. For the cat map, we find the same for the propagator on the plane the same integral kernel conjectured in (HB) using semiclassical methods. We also define a quantum 'integral over phase space' as a trace over the quantum algebra. Using this definition, we proceed to define quantum ergodicity and mixing for maps on the torus. We prove that the quantum cat map and Kronecker map are both ergodic, but only the cat map is mixing, true to its classical origins. For Planck's constant satisfying the integrality condition h = 1/N, with N/in doubz+, we construct an explicit isomorphism between L2/ (/IR, dx) and the Hilbert space of sections of an N-dimensional vector bundle over a θ-torus T2 of boundary conditions. The basis functions are distributions in L2/ (/IR, dx), given by an infinite comb of Dirac δ-functions. In Bargmann space these distributions take on the form of Jacobi ϑ-functions. Transformations from position to momentum representation can be implemented via a finite N-dimensional discrete Fourier transform. With the θ-torus, we provide a connection between the finite-dimensional quantum maps given in the physics literature and the canonical quantization presented here and found in the language of pseudo-differential operators elsewhere in mathematics circles. Specifically, at a fixed point of the dynamics on the θ-torus, we return a finite-dimensional matrix propagator. We present this connection explicitly for several examples.

Examining action effects in the execution of a skilled soccer kick by using erroneous feedback.

PubMed

Ford, Paul; Hodges, Nicola J; Williams, A Mark

2007-11-01

The authors examined the role of action effects (i.e., ball trajectory) during the performance of a soccer kick. Participants were 20 expert players who kicked a ball over a height barrier toward a ground-level target. The authors occluded participants' vision of the ball trajectory after foot-to-ball contact. Participants in a 1st group received erroneous feedback from a video that showed a ball-trajectory apex approximately 75 cm lower than that of their actual kick, although the ball's landing position was unaltered. Participants in a 2nd group received correct video feedback of both the ball trajectory and the landing position. The erroneous-feedback group showed a significant bias toward higher ball trajectories than did the correct-feedback group. The authors conclude that performers at high levels of skill use the visual consequences of the action to plan and execute an action.

Kickdown control for a motor vehicle automatic transmission with two stage kickdown

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

Higashi, H.; Waki, K.; Fukuiri, M.

This patent describes a vehicle automatic transmission. This transmission consists of a hydraulic torque converter, a transmission gear mechanism connected with the torque converter and has at least three gear stages of different gear ratios for foward drive, friction for selecting one of the gear stages. A kick down control which consists of a first shift down circuit for controlling the friction so that the transmission gear mechanism is shifted down from a high gear stage to a lower gear stage. A kick down solenoid is provided in the first shift down circuit for controlling the first shift down circuitmore » and a kick down switch is adapted to be actuated by an engine control member. When the engine control member is moved substantially to a full power position to thereby control the kick down solenoid effects a shift down from a high gear stage to a lower gear stage.« less

Simulations of dolphin kick swimming using smoothed particle hydrodynamics.

PubMed

Cohen, Raymond C Z; Cleary, Paul W; Mason, Bruce R

2012-06-01

In competitive human swimming the submerged dolphin kick stroke (underwater undulatory swimming) is utilized after dives and turns. The optimal dolphin kick has a balance between minimizing drag and maximizing thrust while also minimizing the physical exertion required of the swimmer. In this study laser scans of athletes are used to provide realistic swimmer geometries in a single anatomical pose. These are rigged and animated to closely match side-on video footage. Smoothed Particle Hydrodynamics (SPH) fluid simulations are performed to evaluate variants of this swimming stroke technique. This computational approach provides full temporal and spatial information about the flow moving around the deforming swimmer model. The effects of changes in ankle flexibility and stroke frequency are investigated through a parametric study. The results suggest that the net streamwise force on the swimmer is relatively insensitive to ankle flexibility but is strongly dependent on kick frequency. Crown Copyright © 2011. Published by Elsevier B.V. All rights reserved.

Spectral stability of unitary network models

NASA Astrophysics Data System (ADS)

Asch, Joachim; Bourget, Olivier; Joye, Alain

2015-08-01

We review various unitary network models used in quantum computing, spectral analysis or condensed matter physics and establish relationships between them. We show that symmetric one-dimensional quantum walks are universal, as are CMV matrices. We prove spectral stability and propagation properties for general asymptotically uniform models by means of unitary Mourre theory.

Experiments with trapped ions and ultrafast laser pulses

NASA Astrophysics Data System (ADS)

Johnson, Kale Gifford

Since the dawn of quantum information science, laser-cooled trapped atomic ions have been one of the most compelling systems for the physical realization of a quantum computer. By applying qubit state dependent forces to the ions, their collective motional modes can be used as a bus to realize entangling quantum gates. Ultrafast state-dependent kicks [1] can provide a universal set of quantum logic operations, in conjunction with ultrafast single qubit rotations [2], which uses only ultrafast laser pulses. This may present a clearer route to scaling a trapped ion processor [3]. In addition to the role that spin-dependent kicks (SDKs) play in quantum computation, their utility in fundamental quantum mechanics research is also apparent. In this thesis, we present a set of experiments which demonstrate some of the principle properties of SDKs including ion motion independence (we demonstrate single ion thermometry from the ground state to near room temperature and the largest Schrodinger cat state ever created in an oscillator), high speed operations (compared with conventional atom-laser interactions), and multi-qubit entanglement operations with speed that is not fundamentally limited by the trap oscillation frequency. We also present a method to provide higher stability in the radial mode ion oscillation frequencies of a linear radiofrequency (rf) Paul trap-a crucial factor when performing operations on the rf-sensitive modes. Finally, we present the highest atomic position sensitivity measurement of an isolated atom to date of 0.5 nm Hz. (-1/2) with a minimum uncertaintyof 1.7 nm using a 0.6 numerical aperature (NA) lens system, along with a method to correct aberrations and a direct position measurement of ion micromotion (the inherent oscillations of an ion trapped in an oscillating rf field). This development could be used to directly image atom motion in the quantum regime, along with sensing forces at the yoctonewton [10. (-24) N)] scale forgravity sensing, and 3D imaging of atoms from static to higher frequency motion. These ultrafast atomic qubit manipulation tools demonstrate inherent advantages over conventional techniques, offering a fundamentally distinct regime of control and speed not previously achievable.

Forty-photon-per-pulse spectral phase retrieval by shaper-assisted modified interferometric field autocorrelation.

PubMed

Hsu, Chen-Shao; Chiang, Hsin-Chien; Chuang, Hsiu-Po; Huang, Chen-Bin; Yang, Shang-Da

2011-07-15

We retrieve the spectral phase of 400 fs pulses at 1560 nm with 5.2 aJ coupled pulse energy (40 photons) by the modified interferometric field autocorrelation method, using a pulse shaper and a 5 cm long periodically poled lithium niobate waveguide. The carrier-envelope phase control of the shaper can reduce the fringe density of the interferometric trace and permits longer lock-in time constants, achieving a sensitivity of 2.7×10(-9) mW(2) (40 times better than the previous record for self-referenced nonlinear pulse measurement). The high stability of the pulse shaper allows for accurate and reproducible measurements of complicated spectral phases. © 2011 Optical Society of America

The second phase of bipolar, nanosecond-range electric pulses determines the electroporation efficiency.

PubMed

Pakhomov, Andrei G; Grigoryev, Sergey; Semenov, Iurii; Casciola, Maura; Jiang, Chunqi; Xiao, Shu

2018-03-29

Bipolar cancellation refers to a phenomenon when applying a second electric pulse reduces ("cancels") cell membrane damage by a preceding electric pulse of the opposite polarity. Bipolar cancellation is a reason why bipolar nanosecond electric pulses (nsEP) cause weaker electroporation than just a single unipolar phase of the same pulse. This study was undertaken to explore the dependence of bipolar cancellation on nsEP parameters, with emphasis on the amplitude ratio of two opposite polarity phases of a bipolar pulse. Individual cells (CHO, U937, or adult mouse ventricular cardiomyocytes (VCM)) were exposed to either uni- or bipolar trapezoidal nsEP, or to nanosecond electric field oscillations (NEFO). The membrane injury was evaluated by time-lapse confocal imaging of the uptake of propidium (Pr) or YO-PRO-1 (YP) dyes and by phosphatidylserine (PS) externalization. Within studied limits, bipolar cancellation showed little or no dependence on the electric field intensity, pulse repetition rate, chosen endpoint, or cell type. However, cancellation could increase for larger pulse numbers and/or for longer pulses. The sole most critical parameter which determines bipolar cancellation was the phase ratio: maximum cancellation was observed with the 2nd phase of about 50% of the first one, whereas a larger 2nd phase could add a damaging effect of its own. "Swapping" the two phases, i.e., delivering the smaller phase before the larger one, reduced or eliminated cancellation. These findings are discussed in the context of hypothetical mechanisms of bipolar cancellation and electroporation by nsEP. Copyright © 2018 Elsevier B.V. All rights reserved.

The Effect of Fatigue-Induced Changes in Eggbeater-Kick Kinematics on Performance and Risk of Injury.

PubMed

Oliveira, Nuno; Saunders, David H; Sanders, Ross H

2016-01-01

To investigate the effects of fatigue on the vertical force and kinematics of the lower limbs during maximal water polo eggbeater kicking. Twelve male water polo players maintained as high a position as possible while performing the eggbeater kick with the upper limbs raised out of the water until they were unable to keep the top of the sternum (manubrium) above water. Data comprising 27 complete eggbeater-kick cycles were extracted corresponding to 9 cycles of the initial nonfatigued (0%), 50% time point (50%), and final fatigued (100%) periods of the trial. Vertical force, foot speed, and hip-, knee-, and ankle-joint angles were calculated. Mean vertical force (0%, 212.2 N; 50%, 184.5 N; 100%, 164.3 N) progressively decreased with time. Speed of the feet (0.4 m/s), hip abduction (2.9°), and flexion (3.6°) decreased with fatigue, while hip internal rotation (3.6°) and ankle inversion (4°) increased with fatigue. Average angular velocity decreased for all joint motions. Eggbeater-kick performance decreases with fatigue. Inability to maintain foot speeds and hip and ankle actions with progressing fatigue diminishes the ability of the player to produce vertical force during the cycle. Increased internal rotation of the hip when fatigued and the large eversion/abduction of the ankle during the cycle may be predisposing factors for the prevalence of patellofemoral pain syndrome observed among eggbeater-kick performers. Appropriate training interventions that can limit the effects of fatigue on performance and injury risk should be considered.

Measuring the force of punches and kicks among combat sport athletes using a modified punching bag with an embedded accelerometer.

PubMed

Buśko, Krzysztof; Staniak, Zbigniew; Szark-Eckardt, Mirosława; Nikolaidis, Pantelis Theodoros; Mazur-Różycka, Joanna; Łach, Patrycja; Michalski, Radosław; Gajewski, Jan; Górski, Michał

2016-01-01

The main aim of the study was to design a new system to measure punching and kicking forces as well as reaction times in combat sport athletes. In addition, the study examined whether there were any intergender differences in the force of punches thrown by boxers and kicking forces delivered by taekwondo athletes. Boxers (male, n = 13; female, n = 7) were examined for the force of single straight punches and taekwondo athletes (male, n = 14; female, n = 14) for force of single Apdolio and Dwit Chagi kicks. The punching bag was equipped with acceleration transducers and gyroscopes embedded in a cylinder covered with a layer to absorb shock as well as a set of colour signal diodes. Value of the punching bag's acceleration was used for calculating: strike force; the punching location on the bag; and time of a strike. The relative error of force calculation was 3%; the relative error in acceleration measurement was less than 1%. The force of a straight rear-hand punch was greater than the force of a lead-hand punch among male and female boxers. The force of Apdolio kick delivered with a rear leg was greater compared to a lead leg among female and male taekwondo athletes. Significant gender differences were noticed in the force in both types of kicks. In boxers, intergender differences were reported only for the force of a punch thrown with the rear hand. Based on these findings, it was concluded that the modified punching bag is a good diagnostic tool for combat sports.

Phases of QCD3 from non-SUSY Seiberg duality and brane dynamics

NASA Astrophysics Data System (ADS)

Armoni, Adi; Niarchos, Vasilis

2018-05-01

We consider a nonsupersymmetric USp Yang-Mills Chern-Simons gauge theory coupled to fundamental flavors. The theory is realised in type-IIB string theory via an embedding in a Hanany-Witten brane configuration which includes an orientifold and antibranes. We argue that the theory admits a magnetic Seiberg dual. Using the magnetic dual we identify dynamics in field theory and brane physics that correspond to various phases, obtaining a better understanding of three-dimensional bosonization and dynamical breaking of flavor symmetry in USp QCD3 theory. In field theory both phases correspond to magnetic "squark" condensation. In string theory, they correspond to open string tachyon condensation and brane reconnection. We also discuss other phases where the magnetic `squark' is massive. Finally, we briefly comment on the case of unitary gauge groups.

VO2 Kinetics in All-out Arm Stroke, Leg Kick and Whole Stroke Front Crawl 100-m Swimming.

PubMed

Rodríguez, F A; Lätt, E; Jürimäe, J; Maestu, J; Purge, P; Rämson, R; Haljaste, K; Keskinen, K L; Jürimäe, T

2016-03-01

The VO2 response to extreme-intensity exercise and its relationship with sports performance are largely unexplored. This study investigated the pulmonary VO2 kinetics during all-out 100-m front crawl whole stroke swimming (S), arm stroke (A) and leg kick (L). 26 male and 10 female competitive swimmers performed an all-out S trial followed by A and L of equal duration in random order. Breath-by-breath VO2 was measured using a snorkel attached to a portable gas analyzer. Mean (±SD) primary component parameters and peak blood lactate (Lapeak) during S, A, and L were, respectively: time delay (s), 14.2 ± 4.7, 14.3 ± 4.5, 15.6 ± 5.1; amplitude (ml·kg(-1)·min(-1)), 46.8 ± 6.1, 37.3 ± 6.9, 41.0 ± 4.7; time constant (τ, s): 9.2 ± 3.2, 12.4 ± 4.7, 10.1 ± 3.2; Lapeak (mmol·l(-1)), 6.8 ± 3.1, 6.3 ± 2.5, 7.9 ± 2.8. During A and L respectively, 80% and 87% of amplitude in S was reached, whereas A+L were 68% greater than in S. 100-m performance was associated to shorter cardiodynamic phase and greater VO2 amplitude and Lapeak (accounting up to 61% of performance variance), but not to τ. We conclude that (i) VO2 gain was proportional to exercise intensity and muscle mass involved, (ii) kicking is metabolically less efficient, and (iii) the main limiting factor of peak VO2 appears to be O2 delivery and not muscle extraction. © Georg Thieme Verlag KG Stuttgart · New York.

COST-EFFECTIVENESS OF STRUCTURED EDUCATION IN CHILDREN WITH TYPE-1 DIABETES MELLITUS.

PubMed

Basarir, Hasan; Brennan, Alan; Jacques, Richard; Pollard, Daniel; Stevens, Katherine; Freeman, Jennifer; Wales, Jerry; Price, Katherine

2016-01-01

Kids in Control OF Food (KICk-OFF) is a 5-day structured education program for 11- to 16-year-olds with type 1 diabetes mellitus (T1DM) who are using multiple daily insulin injections. This study evaluates the cost-effectiveness of the KICk-OFF education program compared with the usual care using data from the KICk-OFF trial. The short-term within-trial analysis covers the 2-year postintervention period. Data on glycated hemoglobin (HbA1c), severe hypoglycemia, and diabetic ketoacidosis (DKA) were collected over a 2-year follow-up period. Sub-group analyses have been defined on the basis of baseline HbA1c being below 7.5 percent (58.5 mmol/mol) (low group), between 7.5 percent and 9.5 percent (80.3 mmol/mol) (medium group), and over 9.5 percent (high group). The long-term cost-effectiveness evaluation has been conducted by using The Sheffield Type 1 Diabetes Policy Model, which is a patient-level simulation model on T1DM. It includes long-term microvascular (retinopathy, neuropathy, and nephropathy) and macrovascular (myocardial infarction, stroke, revascularization, and angina) diabetes-related complications and acute adverse events (severe hypoglycemia and DKA). The most favorable within-trial scenario for the KICk-OFF arm led to an incremental cost-effectiveness ratio (ICER) of £23,688 (base year 2009) with a cost-effectiveness probability of 41.3 percent. Simulating the long-term complications using the full cohort data, the mean ICER for the base case was £28,813 (base year 2011) and the probability of the KICk-OFF intervention being cost-effective at £20,000/QALY threshold was 42.6 percent, with considerable variation due to treatment effect duration. For the high HbA1c sub-group, the KICk-OFF arm was "dominant" (meaning it provided better health gains at lower costs than usual care) over the usual care arm in each scenario considered. For the whole study population, the cost-effectiveness of KICk-OFF depends on the assumption for treatment effect duration. For the high baseline HbA1c sub-group, KICk-OFF arm was estimated to be dominant over the usual care arm regardless of the assumption on the treatment effect duration.

Gain-phase modulation in chirped-pulse amplification

NASA Astrophysics Data System (ADS)

Shen, Yijie; Gao, Gan; Meng, Yuan; Fu, Xing; Gong, Mali

2017-10-01

The cross-modulation between the gain and chirped phase in chirped-pulse amplification (CPA) is theoretically and experimentally demonstrated. We propose a gain-phase coupled nonlinear Schrödinger equation (GPC-NLSE) for solving chirped-pulse propagation in a nonlinear gain medium involved in the gain-phase modulation (GPM) process. With the GPC-NLSE, the space-time-frequency-dependent gain, chirped phase, pulse, and spectrum evolutions can be precisely calculated. Moreover, a short-length high-gain Yb-doped fiber CPA experiment is presented in which a self-steepening distortion of the seed pulse is automatically compensated after amplification. This phenomenon can be explained by the GPM theory whereas conventional models cannot. The experimental results for the temporal and spectral intensities show excellent agreement with our theory. Our GPM theory paves the way for further investigations of the finer structures of the pulse and spectrum in CPA systems.

Variational treatment of entanglement in the Dicke model

NASA Astrophysics Data System (ADS)

Bakemeier, L.; Alvermann, A.; Fehske, H.

2015-10-01

We introduce a variational ansatz for the Dicke model that extends mean-field theory through the inclusion of spin-oscillator correlations. The correlated variational state is obtained from the mean-field product state via a unitary transformation. The ansatz becomes correct in the limit of large oscillator frequency and in the limit of a large spin, for which it captures the leading quantum corrections to the classical limit exactly including the spin-oscillator entanglement entropy. We explain the origin of the unitary transformation before we show that the ansatz improves substantially upon mean-field theory, giving near exact results for the ground state energy and very good results for other observables. We then discuss why the ansatz still encounters problems in the transition regime at moderate spin lengths, where it fails to capture the precursors of the superradiant quantum phase transition faithfully. This observation illustrates the principal limits of semi-classical formulations, even after they are extended with correlations and entanglement.

Exciting Quantized Vortex Rings in a Superfluid Unitary Fermi Gas

NASA Astrophysics Data System (ADS)

Bulgac, Aurel

2014-03-01

In a recent article, Yefsah et al., Nature 499, 426 (2013) report the observation of an unusual quantum excitation mode in an elongated harmonically trapped unitary Fermi gas. After phase imprinting a domain wall, they observe collective oscillations of the superfluid atomic cloud with a period almost an order of magnitude larger than that predicted by any theory of domain walls, which they interpret as a possible new quantum phenomenon dubbed ``a heavy soliton'' with an inertial mass some 50 times larger than one expected for a domain wall. We present compelling evidence that this ``heavy soliton'' is instead a quantized vortex ring by showing that the main aspects of the experiment can be naturally explained within an extension of the time-dependent density functional theory (TDDFT) to superfluid systems. The numerical simulations required the solution of some 260,000 nonlinear coupled time-dependent 3-dimensional partial differential equations and was implemented on 2048 GPUs on the Cray XK7 supercomputer Titan of the Oak Ridge Leadership Computing Facility.

Helicity-selective phase-matching and quasi-phase matching of circularly polarized high-order harmonics: towards chiral attosecond pulses

DOE PAGES

Kfir, Ofer; Grychtol, Patrik; Turgut, Emrah; ...

2016-05-23

Phase matching of circularly polarized high-order harmonics driven by counter-rotating bi-chromatic lasers was recently predicted theoretically and demonstrated experimentally. In that work, phase matching was analyzed by assuming that the total energy, spin angular momentum and linear momentum of the photons participating in the process are conserved. Here we propose a new perspective on phase matching of circularly polarized high harmonics. We derive an extended phase matching condition by requiring a new propagation matching condition between the classical vectorial bi-chromatic laser pump and harmonics fields. This allows us to include the influence of the laser pulse envelopes on phase matching.more » Here, we find that the helicity dependent phase matching facilitates generation of high harmonics beams with a high degree of chirality. Indeed, we present an experimentally measured chiral spectrum that can support a train of attosecond pulses with a high degree of circular polarization. Moreover, while the degree of circularity of the most intense pulse approaches unity, all other pulses exhibit reduced circularity. Lastly, this feature suggests the possibility of using a train of attosecond pulses as an isolated attosecond probe for chiral-sensitive experiments.« less

Attosecond twin-pulse control by generalized kinetic heterodyne mixing.

PubMed

Raith, Philipp; Ott, Christian; Pfeifer, Thomas

2011-01-15

Attosecond double-pulse (twin-pulse) production in high-order harmonic generation is manipulated by a combination of two-color and carrier-envelope phase-control methods. As we show in numerical simulations, both relative amplitude and phase of the double pulse can be independently set by making use of multidimensional parameter control. Two technical implementation routes are discussed: kinetic heterodyning using second-harmonic generation and split-spectrum phase-step control.

Thermally controlled femtosecond pulse shaping using metasurface based optical filters

NASA Astrophysics Data System (ADS)

Rahimi, Eesa; Şendur, Kürşat

2018-02-01

Shaping of the temporal distribution of the ultrashort pulses, compensation of pulse deformations due to phase shift in transmission and amplification are of interest in various optical applications. To address these problems, in this study, we have demonstrated an ultra-thin reconfigurable localized surface plasmon (LSP) band-stop optical filter driven by insulator-metal phase transition of vanadium dioxide. A Joule heating mechanism is proposed to control the thermal phase transition of the material. The resulting permittivity variation of vanadium dioxide tailors spectral response of the transmitted pulse from the stack. Depending on how the pulse's spectrum is located with respect to the resonance of the band-stop filter, the thin film stack can dynamically compress/expand the output pulse span up to 20% or shift its phase up to 360°. Multi-stacked filters have shown the ability to dynamically compensate input carrier frequency shifts and pulse span variations besides their higher span expansion rates.

Evaluation of fins used in underwater swimming.

PubMed

Pendergast, D R; Mollendorf, J; Logue, C; Samimy, S

2003-01-01

Underwater swimmers use fins which augment thrust to overcome drag and propel the diver. The VdotO2 of swimming as a function of speed, velocity as a function of kick frequency, maximal speed (v), maximal oxygen consumption (VdotO2) and the maximal thrust were determined for eight fins in 10 male divers swimming at 1.25 m depth in a 60 m annular pool. A theoretical analysis of fin cycles was also performed. VdotO2 increased as a second order polynomial as a function of velocity; VdotO2 = 0.045 + 1.65B V + 1.66 (2) V2 (r2 = 0.997), VdotO2 = 0.25 + 1.03 V + 1.83 V2 (r2 = 0.997) and VdotO2 = -0.15 + 2.26 V + 1.49 V2 (r2 = 0.997), for least, average and most economical fins respectively. Kick frequency increased linearly with velocity and had a unique movement path (signature), giving theoretical values that agreed with the measured thrust, drag and efficiency. In conclusion, virtually all thrust comes from the downward power stroke, with rigid fins kicked deep (high drag), while flexible fins are kicked less deep but with higher frequency (low efficiency). Kick depth and frequency explain the performance of the eight tested fins, and should be optimized to enhance diver performance.

The effects of target distance on pivot hip, trunk, pelvis, and kicking leg kinematics in Taekwondo roundhouse kicks.

PubMed

Kim, Jae-Woong; Kwon, Moon-Seok; Yenuga, Sree Sushma; Kwon, Young-Hoooo

2010-06-01

The study purpose was to investigate the effects of target distance on pivot hip, trunk, pelvis, and kicking leg movements in Taekwondo roundhouse kick. Twelve male black-belt holders executed roundhouse kicks for three target distances (Normal, Short, and Long). Linear displacements of the pivot hip and orientation angles of the pelvis, trunk, right thigh, and right shank were obtained through a three-dimensional video motion analysis. Select displacements, distances, peak orientation angles, and angle ranges were compared among the conditions using one-way repeated measure ANOVA (p < 0.05). Several orientation angle variables (posterior tilt range, peak right-tilted position, peak right-rotated position, peak left-rotated position, and left rotation range of the pelvis; peak hyperextended position and peak right-flexed position of the trunk; peak flexed position, flexion range and peak internal-rotated position of the hip) as well as the linear displacements of the pivot hip and the reach significantly changed in response to different target distances. It was concluded that the adjustment to different target distances was mainly accomplished through the pivot hip displacements, hip flexion, and pelvis left rotation. Target distance mainly affected the reach control function of the pelvis and the linear balance function of the trunk.

Fundamental movement skills testing in children with cerebral palsy.

PubMed

Capio, Catherine M; Sit, Cindy H P; Abernethy, Bruce

2011-01-01

To examine the inter-rater reliability and comparative validity of product-oriented and process-oriented measures of fundamental movement skills among children with cerebral palsy (CP). In total, 30 children with CP aged 6 to 14 years (Mean = 9.83, SD = 2.5) and classified in Gross Motor Function Classification System (GMFCS) levels I-III performed tasks of catching, throwing, kicking, horizontal jumping and running. Process-oriented assessment was undertaken using a number of components of the Test of Gross Motor Development (TGMD-2), while product-oriented assessment included measures of time taken, distance covered and number of successful task completions. Cohen's kappa, Spearman's rank correlation coefficient and tests to compare correlated correlation coefficients were performed. Very good inter-rater reliability was found. Process-oriented measures for running and jumping had significant associations with GMFCS, as did seven product-oriented measures for catching, throwing, kicking, running and jumping. Product-oriented measures of catching, kicking and running had stronger associations with GMFCS than the corresponding process-oriented measures. Findings support the validity of process-oriented measures for running and jumping and of product-oriented measures of catching, throwing, kicking, running and jumping. However, product-oriented measures for catching, kicking and running appear to have stronger associations with functional abilities of children with CP, and are thus recommended for use in rehabilitation processes.

Luteal phase deficiency: abnormal gonadotropin and progesterone secretion patterns.

PubMed

Soules, M R; Clifton, D K; Cohen, N L; Bremner, W J; Steiner, R A

1989-10-01

Luteal phase deficiency (LPD) is a reproductive disorder associated with infertility and spontaneous abortion. This study was undertaken to determine whether LPD might be related to an abnormal pattern of gonadotropin secretion. We tested this hypothesis by evaluating the pattern of pulsatile LH secretion in both the follicular and luteal phases of the menstrual cycle in normal women (n = 21) and women with LPD (n = 20), which was diagnosed on the basis of two out of phase endometrial biopsies. In addition, we sought to determine whether changes in progesterone (P) pulse patterns could account for the decrease in average serum P levels in women with LPD. To this end, we examined the pulse patterns of P and compared these patterns between normal women and those with LPD. Frequent blood sampling was performed in both groups to determine their respective hormone secretion patterns. In the follicular phase, blood samples were obtained every 10 min for 12 h; in the luteal phase the samples were obtained every 10 min for 12 h; in the luteal LH, FSH, and P were assayed in each sample. Pulse detection was performed by an adaptive threshold method of pulse analysis. The LH pulse frequency was significantly higher in the women with LPD than in the normal women in the early follicular phase [P less than 0.05; LPD, 12.8 +/- 1.4 (+/- SE); normal, 8.2 +/- 0.7 pulses/12 h]. LH pulse frequency was similar in the early and late follicular phases in the women with LPD, whereas it was higher in the late follicular phase in normal women. Mean serum FSH levels were not different between groups in both the early and late follicular phases. In the luteal phase the P pulse amplitude and mean serum P level were significantly lower in the LPD group than in the normal women (P less than 0.01). We conclude that 1) a too rapid LH pulse pattern in the early follicular phase may lead to inadequate LH support of the corpus luteum and become manifest as LPD; 2) the mechanism for inadequate P secretion in LPD is decreased P pulse amplitude; 3) the finding of similar serum FSH levels in the two groups in both the early and late follicular phases did not support compromised folliculogenesis as an etiological factor for LPD.

Schlieren Movies of the 8-Inch Diameter Rigid Parachute Model of the Cook Research Laboratory Taken During the Fourth Phase of Testing in the Langley Unitary Plan Wind Tunnel

NASA Technical Reports Server (NTRS)

1958-01-01

Canopy Model IV was tested in four different configuration series. Shroud lines were used in the first three series of tests; none were used in the fourth series. Other variables were Mach number (1.77, 2.17, 2.76), dynamic pressure (290, 250, 155 lb per sq ft), camera speed, and attitude.

Method and apparatus for stabilizing pulsed microwave amplifiers

DOEpatents

Hopkins, Donald B.

1993-01-01

Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

Method and apparatus for stabilizing pulsed microwave amplifiers

DOEpatents

Hopkins, D.B.

1993-01-26

Phase and amplitude variations at the output of a high power pulsed microwave amplifier arising from instabilities of the driving electron beam are suppressed with a feed-forward system that can stabilize pulses which are too brief for regulation by conventional feedback techniques. Such variations tend to be similar during successive pulses. The variations are detected during each pulse by comparing the amplifier output with the low power input signal to obtain phase and amplitude error signals. This enables storage of phase and amplitude correction signals which are used to make compensating changes in the low power input signal during the following amplifier output pulse which suppress the variations. In the preferred form of the invention, successive increments of the correction signals for each pulse are stored in separate channels of a multi-channel storage. Sequential readout of the increments during the next pulse provides variable control voltages to a voltage controlled phase shifter and voltage controlled amplitude modulator in the amplifier input signal path.

Pulsed spatial phase-shifting digital shearography based on a micropolarizer camera

NASA Astrophysics Data System (ADS)

Aranchuk, Vyacheslav; Lal, Amit K.; Hess, Cecil F.; Trolinger, James Davis; Scott, Eddie

2018-02-01

We developed a pulsed digital shearography system that utilizes the spatial phase-shifting technique. The system employs a commercial micropolarizer camera and a double pulse laser, which allows for instantaneous phase measurements. The system can measure dynamic deformation of objects as large as 1 m at a 2-m distance during the time between two laser pulses that range from 30 μs to 30 ms. The ability of the system to measure dynamic deformation was demonstrated by obtaining phase wrapped and unwrapped shearograms of a vibrating object.

Improving the phase response of an atom interferometer by means of temporal pulse shaping

NASA Astrophysics Data System (ADS)

Fang, Bess; Mielec, Nicolas; Savoie, Denis; Altorio, Matteo; Landragin, Arnaud; Geiger, Remi

2018-02-01

We study theoretically and experimentally the influence of temporally shaping the light pulses in an atom interferometer, with a focus on the phase response of the interferometer. We show that smooth light pulse shapes allow rejecting high frequency phase fluctuations (above the Rabi frequency) and thus relax the requirements on the phase noise or frequency noise of the interrogation lasers driving the interferometer. The light pulse shape is also shown to modify the scale factor of the interferometer, which has to be taken into account in the evaluation of its accuracy budget. We discuss the trade-offs to operate when choosing a particular pulse shape, by taking into account phase noise rejection, velocity selectivity, and applicability to large momentum transfer atom interferometry.

Hitomi X-ray studies of giant radio pulses from the Crab pulsar

NASA Astrophysics Data System (ADS)

Hitomi Collaboration; Aharonian, Felix; Akamatsu, Hiroki; Akimoto, Fumie; Allen, Steven W.; Angelini, Lorella; Audard, Marc; Awaki, Hisamitsu; Axelsson, Magnus; Bamba, Aya; Bautz, Marshall W.; Blandford, Roger; Brenneman, Laura W.; Brown, Gregory V.; Bulbul, Esra; Cackett, Edward M.; Chernyakova, Maria; Chiao, Meng P.; Coppi, Paolo S.; Costantini, Elisa; de Plaa, Jelle; de Vries, Cor P.; den Herder, Jan-Willem; Done, Chris; Dotani, Tadayasu; Ebisawa, Ken; Eckart, Megan E.; Enoto, Teruaki; Ezoe, Yuichiro; Fabian, Andrew C.; Ferrigno, Carlo; Foster, Adam R.; Fujimoto, Ryuichi; Fukazawa, Yasushi; Furuzawa, Akihiro; Galeazzi, Massimiliano; Gallo, Luigi C.; Gandhi, Poshak; Giustini, Margherita; Goldwurm, Andrea; Gu, Liyi; Guainazzi, Matteo; Haba, Yoshito; Hagino, Kouichi; Hamaguchi, Kenji; Harrus, Ilana M.; Hatsukade, Isamu; Hayashi, Katsuhiro; Hayashi, Takayuki; Hayashida, Kiyoshi; Hiraga, Junko S.; Hornschemeier, Ann; Hoshino, Akio; Hughes, John P.; Ichinohe, Yuto; Iizuka, Ryo; Inoue, Hajime; Inoue, Yoshiyuki; Ishida, Manabu; Ishikawa, Kumi; Ishisaki, Yoshitaka; Iwai, Masachika; Kaastra, Jelle; Kallman, Tim; Kamae, Tsuneyoshi; Kataoka, Jun; Katsuda, Satoru; Kawai, Nobuyuki; Kelley, Richard L.; Kilbourne, Caroline A.; Kitaguchi, Takao; Kitamoto, Shunji; Kitayama, Tetsu; Kohmura, Takayoshi; Kokubun, Motohide; Koyama, Katsuji; Koyama, Shu; Kretschmar, Peter; Krimm, Hans A.; Kubota, Aya; Kunieda, Hideyo; Laurent, Philippe; Lee, Shiu-Hang; Leutenegger, Maurice A.; Limousin, Olivier O.; Loewenstein, Michael; Long, Knox S.; Lumb, David; Madejski, Greg; Maeda, Yoshitomo; Maier, Daniel; Makishima, Kazuo; Markevitch, Maxim; Matsumoto, Hironori; Matsushita, Kyoko; McCammon, Dan; McNamara, Brian R.; Mehdipour, Missagh; Miller, Eric D.; Miller, Jon M.; Mineshige, Shin; Mitsuda, Kazuhisa; Mitsuishi, Ikuyuki; Miyazawa, Takuya; Mizuno, Tsunefumi; Mori, Hideyuki; Mori, Koji; Mukai, Koji; Murakami, Hiroshi; Mushotzky, Richard F.; Nakagawa, Takao; Nakajima, Hiroshi; Nakamori, Takeshi; Nakashima, Shinya; Nakazawa, Kazuhiro; Nobukawa, Kumiko K.; Nobukawa, Masayoshi; Noda, Hirofumi; Odaka, Hirokazu; Ohashi, Takaya; Ohno, Masanori; Okajima, Takashi; Oshimizu, Kenya; Ota, Naomi; Ozaki, Masanobu; Paerels, Frits; Paltani, Stéphane; Petre, Robert; Pinto, Ciro; Porter, Frederick S.; Pottschmidt, Katja; Reynolds, Christopher S.; Safi-Harb, Samar; Saito, Shinya; Sakai, Kazuhiro; Sasaki, Toru; Sato, Goro; Sato, Kosuke; Sato, Rie; Sawada, Makoto; Schartel, Norbert; Serlemtsos, Peter J.; Seta, Hiromi; Shidatsu, Megumi; Simionescu, Aurora; Smith, Randall K.; Soong, Yang; Stawarz, Łukasz; Sugawara, Yasuharu; Sugita, Satoshi; Szymkowiak, Andrew; Tajima, Hiroyasu; Takahashi, Hiromitsu; Takahashi, Tadayuki; Takeda, Shiníchiro; Takei, Yoh; Tamagawa, Toru; Tamura, Takayuki; Tanaka, Takaaki; Tanaka, Yasuo; Tanaka, Yasuyuki T.; Tashiro, Makoto S.; Tawara, Yuzuru; Terada, Yukikatsu; Terashima, Yuichi; Tombesi, Francesco; Tomida, Hiroshi; Tsuboi, Yohko; Tsujimoto, Masahiro; Tsunemi, Hiroshi; Tsuru, Takeshi Go; Uchida, Hiroyuki; Uchiyama, Hideki; Uchiyama, Yasunobu; Ueda, Shutaro; Ueda, Yoshihiro; Uno, Shiníchiro; Urry, C. Megan; Ursino, Eugenio; Watanabe, Shin; Werner, Norbert; Wilkins, Dan R.; Williams, Brian J.; Yamada, Shinya; Yamaguchi, Hiroya; Yamaoka, Kazutaka; Yamasaki, Noriko Y.; Yamauchi, Makoto; Yamauchi, Shigeo; Yaqoob, Tahir; Yatsu, Yoichi; Yonetoku, Daisuke; Zhuravleva, Irina; Zoghbi, Abderahmen; Terasawa, Toshio; Sekido, Mamoru; Takefuji, Kazuhiro; Kawai, Eiji; Misawa, Hiroaki; Tsuchiya, Fuminori; Yamazaki, Ryo; Kobayashi, Eiji; Kisaka, Shota; Aoki, Takahiro

2018-03-01

To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 σ fluctuations of the X-ray fluxes at the pulse peaks, and the 3 σ upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2-300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and 70-300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) × 10-11 erg cm-2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions.

Role of the N*(1535) in the J/{psi}{yields}p{eta}p and J/{psi}{yields}pK{sup +}{lambda} reactions

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

Geng, L. S.; Oset, E.; Zou, B. S.

2009-02-15

We study the J/{psi}{yields}p{eta}p and J/{psi}{yields}pK{sup +}{lambda} reactions with a unitary chiral approach. We find that the unitary chiral approach, which generates the N*(1535) dynamically, can describe the data reasonably well, particularly the ratio of the integrated cross sections. This study provides further support for the unitary chiral description of the N*(1535). We also discuss some subtle differences between the coupling constants determined from the unitary chiral approach and those determined from phenomenological studies.

Beam splitter phase shifts: Wave optics approach

NASA Astrophysics Data System (ADS)

Agnesi, Antonio; Degiorgio, Vittorio

2017-10-01

We investigate the phase relationships between transmitted and reflected waves in a lossless beam splitter having a multilayer structure, using the matrix approach as outlined in classical optics books. Contrarily to the case of the quantum optics formalism generally employed to describe beam splitters, these matrices are not unitary. In this note we point out the existence of general relations among the elements of the transfer matrix that describes the multilayer beam splitter. Such relations, which are independent of the detailed structure of the beam splitter, fix the phase shifts between reflected and transmitted waves. It is instructive to see how the results obtained by Zeilinger by using spinor algebra and Pauli matrices can be easily derived from our general relations.

Visualizing spatiotemporal pulse propagation: first-order spatiotemporal couplings in laser pulses.

PubMed

Rhodes, Michelle; Guang, Zhe; Pease, Jerrold; Trebino, Rick

2017-04-10

Even though a general theory of first-order spatiotemporal couplings exists in the literature, it is often difficult to visualize how these distortions affect laser pulses. In particular, it is difficult to show the spatiotemporal phase of pulses in a meaningful way. Here, we propose a general solution to plotting the electric fields of pulses in three-dimensional space that intuitively shows the effects of spatiotemporal phases. The temporal phase information is color-coded using spectrograms and color response functions, and the beam is propagated to show the spatial phase evolution. Using this plotting technique, we generate two- and three-dimensional images and movies that show the effects of spatiotemporal couplings.

Visualizing spatiotemporal pulse propagation: first-order spatiotemporal couplings in laser pulses

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

Rhodes, Michelle; Guang, Zhe; Pease, Jerrold

2017-04-06

Even though a general theory of first-order spatiotemporal couplings exists in the literature, it is often difficult to visualize how these distortions affect laser pulses. In particular, it is difficult to show the spatiotemporal phase of pulses in a meaningful way. We propose a general solution to plotting the electric fields of pulses in three-dimensional space that intuitively shows the effects of spatiotemporal phases. The temporal phase information is color-coded using spectrograms and color response functions, and the beam is propagated to show the spatial phase evolution. In using this plotting technique, we generate two- and three-dimensional images and moviesmore » that show the effects of spatiotemporal couplings.« less

A Defensive Kicking Behavior in Response to Mechanical Stimuli Mediated by Drosophila Wing Margin Bristles.

PubMed

Li, Jiefu; Zhang, Wei; Guo, Zhenhao; Wu, Sophia; Jan, Lily Yeh; Jan, Yuh-Nung

2016-11-02

Mechanosensation, one of the fastest sensory modalities, mediates diverse behaviors including those pertinent for survival. It is important to understand how mechanical stimuli trigger defensive behaviors. Here, we report that Drosophila melanogaster adult flies exhibit a kicking response against invading parasitic mites over their wing margin with ultrafast speed and high spatial precision. Mechanical stimuli that mimic the mites' movement evoke a similar kicking behavior. Further, we identified a TRPV channel, Nanchung, and a specific Nanchung-expressing neuron under each recurved bristle that forms an array along the wing margin as being essential sensory components for this behavior. Our electrophysiological recordings demonstrated that the mechanosensitivity of recurved bristles requires Nanchung and Nanchung-expressing neurons. Together, our results reveal a novel neural mechanism for innate defensive behavior through mechanosensation. We discovered a previously unknown function for recurved bristles on the Drosophila melanogaster wing. We found that when a mite (a parasitic pest for Drosophila) touches the wing margin, the fly initiates a swift and accurate kick to remove the mite. The fly head is dispensable for this behavior. Furthermore, we found that a TRPV channel, Nanchung, and a specific Nanchung-expressing neuron under each recurved bristle are essential for its mechanosensitivity and the kicking behavior. In addition, touching different regions of the wing margin elicits kicking directed precisely at the stimulated region. Our experiments suggest that recurved bristles allow the fly to sense the presence of objects by touch to initiate a defensive behavior (perhaps analogous to touch-evoked scratching; Akiyama et al., 2012). Copyright © 2016 the authors 0270-6474/16/3611275-08$15.00/0.

Kinematic Patterns Associated with the Vertical Force Produced during the Eggbeater Kick.

PubMed

Oliveira, Nuno; Chiu, Chuang-Yuan; Sanders, Ross H

2015-01-01

The purpose of this study was to determine the kinematic patterns that maximized the vertical force produced during the water polo eggbeater kick. Twelve water polo players were tested executing the eggbeater kick with the trunk aligned vertically and with the upper limbs above water while trying to maintain as high a position as possible out of the water for nine eggbeater kick cycles. Lower limb joint angular kinematics, pitch angles and speed of the feet were calculated. The vertical force produced during the eggbeater kick cycle was calculated using inverse dynamics for the independent lower body segments and combined upper body segments, and a participant-specific second-degree regression equation for the weight and buoyancy contributions. Vertical force normalized to body weight was associated with hip flexion (average, r = 0.691; maximum, r = 0.791; range of motion, r = 0.710), hip abduction (maximum, r = 0.654), knee flexion (average, r = 0.716; minimum, r = 0.653) and knee flexion-extension angular velocity (r = 0.758). Effective orientation of the hips resulted in fast horizontal motion of the feet with positive pitch angles. Vertical motion of the feet was negatively associated with vertical force. A multiple regression model comprising the non-collinear variables of maximum hip abduction, hip flexion range of motion and knee flexion angular velocity accounted for 81% of the variance in normalized vertical force. For high performance in the water polo, eggbeater kick players should execute fast horizontal motion with the feet by having large abduction and flexion of the hips, and fast extension and flexion of the knees.

Influence of maturation on instep kick biomechanics in female soccer athletes.

PubMed

Lyle, Mark A; Sigward, Susan M; Tsai, Liang-Ching; Pollard, Christine D; Powers, Christopher M

2011-10-01

The purpose of this study was to compare kicking biomechanics between young female soccer players at two different stages of physical maturation and to identify biomechanical predictors of peak foot velocity. Swing and stance limb kinematics and kinetics were recorded from 20 female soccer players (10 prepubertal, 10 postpubertal) while kicking a soccer ball using an angled two-step approach. Peak foot velocity as well as hip and knee kinematics and kinetics were compared between groups using independent-samples t-tests. Pearson correlation coefficients and stepwise multiple regression were used to identify predictors of peak foot velocity. Peak foot velocity and the peak swing limb net hip flexor moment was significantly greater in the postpubertal group when compared with the prepubertal group (13.4 vs 11.6 m·s(-1), P = 0.003; 1.22 vs 1.07 N·m·kg(-1)·m(-1), P = 0.03). Peak stance limb hip and knee extensor moments were not different between groups. Although the peak swing limb hip and knee flexion angles were similar between groups, the postpubertal group demonstrated significantly less peak stance limb hip and knee flexion angles when compared with the prepubertal group (P < 0.001 and P = 0.045). Using a linear regression model, swing limb peak hip flexor moment and peak swing limb hip extension range of motion combined to explain 65% of the variance in peak foot velocity. Despite a difference in stance limb kinematics, similar swing limb kinematics between groups indicates that the prepubertal female athletes kicked with a mature swing limb kick pattern. The ability to generate a large hip flexor moment of the swing limb seems to be an important factor for improving kicking performance in young female soccer players.

Differences in neuromuscular control between impact and no impact roundhouse kick in athletes of different skill levels.

PubMed

Quinzi, Federico; Camomilla, Valentina; Felici, Francesco; Di Mario, Alberto; Sbriccoli, Paola

2013-02-01

This study aimed at investigating two aspects of neuromuscular control around the hip and knee joint while executing the roundhouse kick (RK) using two techniques: Impact RK (IRK) at trunk level and No-Impact RK at face level (NIRK). The influence of technical skill level was also investigated by comparing two groups: elite Karateka and Amateurs. Surface electromyographic (sEMG) signals have been recorded from the Vastus Lateralis (VL), Biceps Femoris (BF), Rectus Femoris (RF), Gluteus Maximum (GM) and Gastrocnemious (GA) muscles of the kicking leg in six Karateka and six Amateurs performing the RKs. Hip and knee kinematics were also assessed. EMG data were rectified, filtered and normalized to the maximal value obtained for each muscle over all trials; co-activation (CI) indexes of antagonist vs. overall (agonist and antagonist) activity were computed for hip and knee flexion and extension. Muscle Fiber Conduction Velocity (CV) obtained from VL and BF muscles was assessed as well. The effect of group and kick on angular velocity, CIs, and CVs was tested through a two-way ANOVA (p < 0.05). An effect of group was showed in both kicks. Karateka presented higher knee and hip angular velocity; higher BF-CV (IRK: 5.1 ± 1.0 vs. 3.5 ± 0.5 m/s; NIRK: 5.7 ± 1.3 vs. 4.1 ± 0.5 m/s), higher CIs for hip movements and knee flexion and lower CI for knee extension. The results obtained suggest the presence of a skill-dependent activation strategy in the execution of the two kicks. CV results are suggestive of an improved ability of elite Karateka to recruit fast MUs as a part of training induced neuromuscular adaptation. Copyright © 2012 Elsevier Ltd. All rights reserved.

Anaerobic upper and lower body power measurements and perception of fatigue during a kick boxing match.

PubMed

Ouergui, I; Hammouda, O; Chtourou, H; Zarrouk, N; Rebai, H; Chaouachi, A

2013-10-01

Objective of the study was to determine the effects of a kick-boxing match on muscle power of the upper and lower body as well as the associated perceived exertion in young men. Eighteen well trained kick-boxers volunteered to participate in a competitive sparring bout preceded and followed by three anaerobic tests as follow: squat jump (SJ) and counter movement jump (CMJ) for legs and 30-s Wingate test for arms. The sparring bout consisted of three 2 min rounds with 1 min recovery period in-between. Blood lactate (BL), heart rate (HR) and rating of perceived exertion (RPE) were analyzed before and after each round. The results showed that vertical jump distance in SJ and CMJ were significantly lower after the kick-boxing match (27.92±3.84 vs. 25.28±4.39 cm; 29.8±5.33 vs 28.48±4.64 cm, for SJ and CMJ respectively). Likewise, peak and mean power in the Wingate test decreased significantly after the sparring bout (5.89±0. 69 vs. 5.26±0.66 W•kg-1 and 4.51±0.53 vs. 4.12±0.51 W•kg-1 for PP and MP respectively; P<0.001). Moreover, we found a significant increase in BL, HR, and RPE after the kick-boxing match (P<0.001). BL increased significantly after the second and third round from the post round one values' (P<0.001). These findings showed that a single kick-boxing match is of sufficient intensity to stress the anaerobic metabolism. Thus, training protocols should include exercises that train the anaerobic energetic pathways for upper and lower body.

Beam motions near separatrix

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

M. Ball et al.

1999-05-04

Experimental data on particle motion near the separatrix of the one dimensional (1-D) fourth-integer islands are an-alyzed. When the beam bunch is initially kicked to the separatrix orbit, we observed a strong decoherence in the coherent betatron motion. We find that, through intensive particle tracking simulation analysis, the decoherence has resulted from the beam being split into beamlets in the beta-tron phase space. However, we also observe an unexpected recoherence of coherence signal, which may result form a modulated closed orbit or the homoclinic structure near the separatrix.

Generation of helical Ince-Gaussian beams with a liquid-crystal display.

PubMed

Bentley, Joel B; Davis, Jeffrey A; Bandres, Miguel A; Gutiérrez-Vega, Julio C

2006-03-01

We generate helical Ince-Gaussian (HIG) beams by using complex amplitude and phase masks encoded onto a liquid-crystal display (LCD). These beams display an intensity pattern consisting of elliptic rings, whose number and ellipticity can be controlled, and a phase exhibiting a number of in-line vortices, each with a unitary topological charge. We show experimental results that display the properties of these elliptic dark hollow beams. We introduce a novel interference technique for generating the object and reference beams by using a single LCD and show the vortex interference patterns. We expect that these HIG beams will be useful in optical trapping applications.

Generation of helical Ince-Gaussian beams with a liquid-crystal display

NASA Astrophysics Data System (ADS)

Bentley, Joel B.; Davis, Jeffrey A.; Bandres, Miguel A.; Gutiérrez-Vega, Julio C.

2006-03-01

We generate helical Ince-Gaussian (HIG) beams by using complex amplitude and phase masks encoded onto a liquid-crystal display (LCD). These beams display an intensity pattern consisting of elliptic rings, whose number and ellipticity can be controlled, and a phase exhibiting a number of in-line vortices, each with a unitary topological charge. We show experimental results that display the properties of these elliptic dark hollow beams. We introduce a novel interference technique for generating the object and reference beams by using a single LCD and show the vortex interference patterns. We expect that these HIG beams will be useful in optical trapping applications.

Ultra-fast quantum randomness generation by accelerated phase diffusion in a pulsed laser diode.

PubMed

Abellán, C; Amaya, W; Jofre, M; Curty, M; Acín, A; Capmany, J; Pruneri, V; Mitchell, M W

2014-01-27

We demonstrate a high bit-rate quantum random number generator by interferometric detection of phase diffusion in a gain-switched DFB laser diode. Gain switching at few-GHz frequencies produces a train of bright pulses with nearly equal amplitudes and random phases. An unbalanced Mach-Zehnder interferometer is used to interfere subsequent pulses and thereby generate strong random-amplitude pulses, which are detected and digitized to produce a high-rate random bit string. Using established models of semiconductor laser field dynamics, we predict a regime of high visibility interference and nearly complete vacuum-fluctuation-induced phase diffusion between pulses. These are confirmed by measurement of pulse power statistics at the output of the interferometer. Using a 5.825 GHz excitation rate and 14-bit digitization, we observe 43 Gbps quantum randomness generation.

Judging where a ball will go: the case of curved free kicks in football.

PubMed

Craig, Cathy M; Berton, Eric; Rao, Guillaume; Fernandez, Laure; Bootsma, Reinoud J

2006-02-01

This study examined whether adding spin to a ball in the free kick situation in football affects a professional footballer's perception of the ball's future arrival position. Using a virtual reality set-up, participants observed the flight paths of aerodynamically realistic free kicks with (+/-600 rpm) and without sidespin. With the viewpoint being fixed in the centre of the goal, participants had to judge whether the ball would have ended up in the goal or not. Results show that trajectories influenced by the Magnus force caused by sidespin gave rise to a significant shift in the percentage of goal responses. The resulting acceleration that causes the ball to continually change its heading direction as the trajectory unfolds does not seem to be taken into account by the participants when making goal judgments. We conclude that the visual system is not attuned to such accelerated motion, which may explain why goalkeepers appear to misjudge the future arrival point of such curved free kicks.

Judging where a ball will go: the case of curved free kicks in football

NASA Astrophysics Data System (ADS)

Craig, Cathy M.; Berton, Eric; Rao, Guillaume; Fernandez, Laure; Bootsma, Reinoud J.

2006-02-01

This study examined whether adding spin to a ball in the free kick situation in football affects a professional footballer’s perception of the ball’s future arrival position. Using a virtual reality set-up, participants observed the flight paths of aerodynamically realistic free kicks with (±600 rpm) and without sidespin. With the viewpoint being fixed in the centre of the goal, participants had to judge whether the ball would have ended up in the goal or not. Results show that trajectories influenced by the Magnus force caused by sidespin gave rise to a significant shift in the percentage of goal responses. The resulting acceleration that causes the ball to continually change its heading direction as the trajectory unfolds does not seem to be taken into account by the participants when making goal judgments. We conclude that the visual system is not attuned to such accelerated motion, which may explain why goalkeepers appear to misjudge the future arrival point of such curved free kicks.

Discovery of a Sweet Spot on the Foot with a Smart Wearable Soccer Boot Sensor That Maximizes the Chances of Scoring a Curved Kick in Soccer.

PubMed

Fuss, Franz Konstantin; Düking, Peter; Weizman, Yehuda

2018-01-01

This paper provides the evidence of a sweet spot on the boot/foot as well as the method for detecting it with a wearable pressure sensitive device. This study confirmed the hypothesized existence of sweet and dead spots on a soccer boot or foot when kicking a ball. For a stationary curved kick, kicking the ball at the sweet spot maximized the probability of scoring a goal (58-86%), whereas having the impact point at the dead zone minimized the probability (11-22%). The sweet spot was found based on hypothesized favorable parameter ranges (center of pressure in x/y-directions and/or peak impact force) and the dead zone based on hypothesized unfavorable parameter ranges. The sweet spot was rather concentrated, independent of which parameter combination was used (two- or three-parameter combination), whereas the dead zone, located 21 mm from the sweet spot, was more widespread.

Review: Modelling of meniscus of knee joint during soccer kicking

NASA Astrophysics Data System (ADS)

Azrul Hisham Mohd Adib, Mohd; Firdaus Jaafar, Mohd

2013-12-01

Knee is a part of the body that located between thigh and shank is one of the most complicated and largest joints in the human body. The common injuries that occur are ligaments, meniscus or bone fracture. During soccer games, the knee is the most critical part that will easily injure due to the shock from an external impact. Torn meniscus is one of the effects. This study will investigate the effect towards the meniscus within the knee joint during soccer ball kicking. We conduct a literary review of 14 journals that discuss the general view of meniscus and also soccer kicking. The selected topics for this review paper are meniscal function, meniscal movement, meniscal tears and also instep kick. As a finding, statistics show that most meniscal tears (73%) occurred in athletes who were soccer players, basketball players or skiers. The tear is frequently happening at the medial side rather than lateral side with a percentage of 70%.

Unitary IPSPs evoked by interneurons at the stratum radiatum-stratum lacunosum-moleculare border in the CA1 area of the rat hippocampus in vitro

PubMed Central

Vida, Imre; Halasy, Katalin; Szinyei, Csaba; Somogyi, Peter; Buhl, Eberhard H

1998-01-01

Hippocampal non-principal neurons at the stratum radiatum-stratum lacunosum-moleculare border (R-LM interneurons) of the CA1 area may constitute several cell classes and have been implicated in the generation of GABAergic unitary IPSPs. Using biocytin-filled electrodes we recorded R-LM interneurons intracellularly in vitro and determined their postsynaptic effects in concomitantly recorded pyramidal cells. Light microscopic analysis revealed four populations of R-LM interneurons with distinct axons: (1) basket cells (n= 4) with axons predominantly ramifying in the pyramidal cell layer; (2) Schaffer collateral/commissural pathway-associated interneurons (n= 10) stratifying in stratum radiatum and, to a lesser extent, stratum oriens; (3) perforant pathway-associated interneurons (n= 6) innervating the perforant path termination zone in stratum lacunosum-moleculare of the CA1 area as well as equivalent portions of the dentate gyrus and subiculum; and (4) neurogliaform interneurons (n= 2) characterized by their dense, compact axonal and dendritic arbour. Random electron microscopic sampling of synaptic targets revealed a preponderance of pyramidal neurons as postsynaptic elements. Basket cells had a synaptic target preference for somata and proximal dendrites, whereas the remainder of R-LM interneurons innervated dendritic shafts and spines. The axon of dendrite-targeting cells formed up to six putative contacts with individual postsynaptic pyramidal cells. Anatomically recovered R-LM interneurons (n= 22) had a mean resting membrane potential of -56.7 ± 3.6 mV, a membrane time constant of 12.9 ± 7.7 ms and an input resistance of 86.4 ± 29.2 MΩ. Depolarizing current pulses generally elicited overshooting action potentials (70.8 ± 6.9 mV) which had a mean duration, when measured at half-amplitude, of 0.7 ± 0.1 ms. In response to prolonged (> 200 ms) depolarizing current pulses all R-LM interneurons displayed (a varying degree of) spike frequency adaptation. Basket cells, Schaffer-associated and neurogliaform interneurons elicited small-amplitude (< 2 mV), short-latency IPSPs in postsynaptic pyramids (n= 5, 13 and 1, respectively). Those interactions in which an effect was elicited with the repetitive activation of the presynaptic neuron (n= 13) showed a substantial degree of postsynaptic response summation. Unitary IPSPs had fast kinetics and, whenever tested (n= 5; 1 basket cell and 4 Schaffer-associated interneurons), were abolished by the GABAA receptor antagonist bicuculline. Thus, R-LM interneurons comprise several distinct populations which evoke fast GABAA receptor-mediated IPSPs. The domain-specific innervation of postsynaptic pyramidal cells suggests functionally diverse effects on the integration of afferent information in functionally non-equivalent compartments of pyramidal cells. PMID:9503336

Experiments with linear compressors for phase shifting in pulse tube crycoolers

NASA Astrophysics Data System (ADS)

Lewis, Michael; Bradley, Peter; Radebaugh, Ray

2012-06-01

For the past year NIST has been investigating the use of mechanical phase shifters as warm expanders for pulse tube cryocoolers. Unlike inertance tubes, which have a limited phase shifting ability at low acoustic powers, mechanical phase shifters have the ability to provide nearly any phase angle between the mass flow and the pressure. We discuss our results with experiments and modeling on a commercially available miniature linear compressor operating as an expander on the warm-end of a 4 K pulse tube, whose temperature is nominally about 35 K. We also present results on experiments with a linear compressor operating at room temperature but coupled to the 4 K stage through secondary regenerators and secondary pulse tubes. Experiments on a small pulse tube test apparatus with both 4He and 3He showed improved efficiency when using the mechanical expander over that of inertance tubes. Phase locking techniques using function generators and power amplifiers for control of phase angle are detailed. The use of expanders demonstrates flexible control in optimizing phase angles for improved cryocooler performance.

Computational modeling and analysis of the hydrodynamics of human swimming

NASA Astrophysics Data System (ADS)

von Loebbecke, Alfred

Computational modeling and simulations are used to investigate the hydrodynamics of competitive human swimming. The simulations employ an immersed boundary (IB) solver that allows us to simulate viscous, incompressible, unsteady flow past complex, moving/deforming three-dimensional bodies on stationary Cartesian grids. This study focuses on the hydrodynamics of the "dolphin kick". Three female and two male Olympic level swimmers are used to develop kinematically accurate models of this stroke for the simulations. A simulation of a dolphin undergoing its natural swimming motion is also presented for comparison. CFD enables the calculation of flow variables throughout the domain and over the swimmer's body surface during the entire kick cycle. The feet are responsible for all thrust generation in the dolphin kick. Moreover, it is found that the down-kick (ventral position) produces more thrust than the up-kick. A quantity of interest to the swimming community is the drag of a swimmer in motion (active drag). Accurate estimates of this quantity have been difficult to obtain in experiments but are easily calculated with CFD simulations. Propulsive efficiencies of the human swimmers are found to be in the range of 11% to 30%. The dolphin simulation case has a much higher efficiency of 55%. Investigation of vortex structures in the wake indicate that the down-kick can produce a vortex ring with a jet of accelerated fluid flowing through its center. This vortex ring and the accompanying jet are the primary thrust generating mechanisms in the human dolphin kick. In an attempt to understand the propulsive mechanisms of surface strokes, we have also conducted a computational analysis of two different styles of arm-pulls in the backstroke and the front crawl. These simulations involve only the arm and no air-water interface is included. Two of the four strokes are specifically designed to take advantage of lift-based propulsion by undergoing lateral motions of the hand (sculling) and by orienting the palm obliquely to the flow. The focus of the current study is on quantifying the relative contributions of drag and lift to thrust production and use this as a basis for determining the relative effectiveness the stroke styles.

Mode-locking of a terahertz laser by direct phase synchronization.

PubMed

Maysonnave, J; Maussang, K; Freeman, J R; Jukam, N; Madéo, J; Cavalié, P; Rungsawang, R; Khanna, S P; Linfield, E H; Davies, A G; Beere, H E; Ritchie, D A; Dhillon, S S; Tignon, J

2012-09-10

A novel scheme to achieve mode-locking of a multimode laser is demonstrated. Traditional methods to produce ultrashort laser pulses are based on modulating the cavity gain or losses at the cavity roundtrip frequency, favoring the pulsed emission. Here, we rather directly act on the phases of the modes, resulting in constructive interference for the appropriated phase relationship. This was performed on a terahertz quantum cascade laser by multimode injection seeding with an external terahertz pulse, resulting in phase mode-locked terahertz laser pulses of 9 ps duration, characterized unambiguously in the time domain.

Unitary or Non-Unitary Nature of Working Memory? Evidence from Its Relation to General Fluid and Crystallized Intelligence

ERIC Educational Resources Information Center

Dang, Cai-Ping; Braeken, Johan; Ferrer, Emilio; Liu, Chang

2012-01-01

This study explored the controversy surrounding working memory: whether it is a unitary system providing general purpose resources or a more differentiated system with domain-specific sub-components. A total of 348 participants completed a set of 6 working memory tasks that systematically varied in storage target contents and type of information…

Efficient Nonlocal M-Control and N-Target Controlled Unitary Gate Using Non-symmetric GHZ States

NASA Astrophysics Data System (ADS)

Chen, Li-Bing; Lu, Hong

2018-03-01

Efficient local implementation of a nonlocal M-control and N-target controlled unitary gate is considered. We first show that with the assistance of two non-symmetric qubit(1)-qutrit(N) Greenberger-Horne-Zeilinger (GHZ) states, a nonlocal 2-control and N-target controlled unitary gate can be constructed from 2 local two-qubit CNOT gates, 2 N local two-qutrit conditional SWAP gates, N local qutrit-qubit controlled unitary gates, and 2 N single-qutrit gates. At each target node, the two third levels of the two GHZ target qutrits are used to expose one and only one initial computational state to the local qutrit-qubit controlled unitary gate, instead of being used to hide certain states from the conditional dynamics. This scheme can be generalized straightforwardly to implement a higher-order nonlocal M-control and N-target controlled unitary gate by using M non-symmetric qubit(1)-qutrit(N) GHZ states as quantum channels. Neither the number of the additional levels of each GHZ target particle nor that of single-qutrit gates needs to increase with M. For certain realistic physical systems, the total gate time may be reduced compared with that required in previous schemes.

Neodymium glass laser with a phase conjugate mirror producing 220 J pulses at 0.02 Hz repetition rate.

PubMed

Kuzmin, A A; Khazanov, E A; Kulagin, O V; Shaykin, A A

2014-08-25

For pumping multipetawatt Ti:sapphire laser facilities we developed a compact repetitively pulsed laser based on neodymium phosphate glass with pulse energy of 220 J, pulse repetition rate of 0.02 Hz, beam diameter of 43 mm, aperture fill factor of 0.8, and FWHM pulse duration of 30 ns. The phase distortions of laser radiation were compensated by optical phase conjugation via stimulated Brillouin scattering. The depolarization was reduced to 0.4% using linear compensation methods. The beam quality was 2.5 x diffraction limit (150 µrad).

Experimental observation of carrier-envelope-phase effects by multicycle pulses

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

Jha, Pankaj K.; Scully, Marlan O.; Mechanical and Aerospace Engineering and the Princeton Institute for the Science and Technology of Materials, Princeton University, Princeton, New Jersey 08544

2011-03-15

We present an experimental and theoretical study of carrier-envelope-phase (CEP) effects on the population transfer between two bound atomic states interacting with pulses consisting of many cycles. Using intense radio-frequency pulse with Rabi frequency of the order of the atomic transition frequency, we investigate the influence of the CEP on the control of phase-dependent multiphoton transitions between the Zeeman sublevels of the ground state of {sup 87}Rb. Our scheme has no limitation on the duration of the pulses. Extending the CEP control to longer pulses creates interesting possibilities to generate pulses with accuracy that is better than the period ofmore » optical oscillations.« less

All-optical short pulse translation through cross-phase modulation in a VO₂ thin film.

PubMed

Fardad, Shima; Das, Susobhan; Salandrino, Alessandro; Breckenfeld, Eric; Kim, Heungsoo; Wu, Judy; Hui, Rongqing

2016-01-15

VO2 is a promising material for reconfigurable photonic devices due to the ultrafast changes in electronic and optical properties associated with its dielectric-to-metal phase transition. Based on a fiber-optic, pump-probe setup at 1550 nm wavelength window, and by varying the pump-pulse duration, we show that the material phase transition is primarily caused by the pump-pulse energy. For the first time, we demonstrate that the instantaneous optical phase modulation of probe during pump leading edge can be utilized to create short optical pulses at probe wavelength, through optical frequency discrimination. This circumvents the impact of long recovery time well known for the phase transition of VO2.

Rank One Strange Attractors in Periodically Kicked Predator-Prey System with Time-Delay

NASA Astrophysics Data System (ADS)

Yang, Wenjie; Lin, Yiping; Dai, Yunxian; Zhao, Huitao

2016-06-01

This paper is devoted to the study of the problem of rank one strange attractor in a periodically kicked predator-prey system with time-delay. Our discussion is based on the theory of rank one maps formulated by Wang and Young. Firstly, we develop the rank one chaotic theory to delayed systems. It is shown that strange attractors occur when the delayed system undergoes a Hopf bifurcation and encounters an external periodic force. Then we use the theory to the periodically kicked predator-prey system with delay, deriving the conditions for Hopf bifurcation and rank one chaos along with the results of numerical simulations.

Electron dynamics and transverse-kick elimination in a high-field short-period helical microwave undulator

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

Chang, C.; Shumail, M.; Tantawi, S.

2012-10-15

Single electron dynamics for a circular polarized standing wave (CPSW) undulator synthesized from a corrugated cavity operating with a very low-loss HE{sub 11} mode are analyzed. The mechanism of the transverse drift of the CPSW undulator and its elimination are researched, and the tapered-field ends are found effectively to suppress the kick. A prototype of the CPSW undulator with the characters of short undulating-period 1.4 cm, high field K {approx} 1, large aperture {approx} 5 cm, and variable polarization is designed and modeled, whose 3-dimensional electromagnetic fields are used to research the suppression of the transverse kick.

Modeling Kicks from the Merger of Generic Black-hole Binaries

NASA Technical Reports Server (NTRS)

Baker, John G.; Boggs, William D.; Centrella, Joan; Kelly, Bernard J.; McWilliams, Sean T.; Miller, M. Coleman; vanMeter, James R.

2008-01-01

Recent numerical relativistic results demonstrate that the merger of comparable-mass spinning black holes has a maximum "recoil kick" of up to approx. 4000 km/s. However the scaling of these recoil velocities with mass ratio is poorly understood. We present new runs showing that the maximum possible kick parallel to the orbital axis does not scale as approx. eta(sup 2) (where eta is the symmetric mass ratio), as previously proposed, but is more consistent with approx. eta(sup 3). We discuss the effect of this dependence on galactic ejection scenarios and retention of intermediate-mass black holes in globular clusters. S

Dynamical quantum phase transitions in extended transverse Ising models

NASA Astrophysics Data System (ADS)

Bhattacharjee, Sourav; Dutta, Amit

2018-04-01

We study the dynamical quantum phase transitions (DQPTs) manifested in the subsequent unitary dynamics of an extended Ising model with an additional three spin interactions following a sudden quench. Revisiting the equilibrium phase diagram of the model, where different quantum phases are characterized by different winding numbers, we show that in some situations the winding number may not change across a gap closing point in the energy spectrum. Although, usually there exists a one-to-one correspondence between the change in winding number and the number of critical time scales associated with DQPTs, we show that the extended nature of interactions may lead to unusual situations. Importantly, we show that in the limit of the cluster Ising model, three critical modes associated with DQPTs become degenerate, thereby leading to a single critical time scale for a given sector of Fisher zeros.

78 FR 26110 - Kicking Cars and Going Between Rolling Equipment During Flat Switching Operations

Federal Register 2010, 2011, 2012, 2013, 2014

2013-05-03

... Cars and Going Between Rolling Equipment During Flat Switching Operations AGENCY: Federal Railroad... occurred during a railroad switching operation that involved a railroad employee kicking cars and... make recommendations to railroads regarding the adoption of car-handling procedures during flat...

Pulsed photothermal interferometry for spectroscopic gas detection with hollow-core optical fibre

PubMed Central

Lin, Yuechuan; Jin, Wei; Yang, Fan; Ma, Jun; Wang, Chao; Ho, Hoi Lut; Liu, Yang

2016-01-01

Gas detection with hollow-core photonic bandgap fibre (HC-PBF) and pulsed photothermal (PT) interferometry spectroscopy are studied theoretically and experimentally. A theoretical model is developed and used to compute the gas-absorption-induced temperature and phase modulation in a HC-PBF filled with low-concentration of C2H2 in nitrogen. The PT phase modulation dynamics for different pulse duration, peak power and energy of pump beam are numerically modelled, which are supported by the experimental results obtained around the P(9) absorption line of C2H2 at 1530.371 nm. Thermal conduction is identified as the main process responsible for the phase modulation dynamics. For a constant peak pump power level, the phase modulation is found to increase with pulse duration up to ~1.2 μs, while it increases with decreasing pulse duration for a constant pulse energy. It is theoretically possible to achieve ppb level detection of C2H2 with ~1 m length HC-PBF and a pump beam with ~10 ns pulse duration and ~100 nJ pulse energy. PMID:28009011

Pulsed photothermal interferometry for spectroscopic gas detection with hollow-core optical fibre.

PubMed

Lin, Yuechuan; Jin, Wei; Yang, Fan; Ma, Jun; Wang, Chao; Ho, Hoi Lut; Liu, Yang

2016-12-23

Gas detection with hollow-core photonic bandgap fibre (HC-PBF) and pulsed photothermal (PT) interferometry spectroscopy are studied theoretically and experimentally. A theoretical model is developed and used to compute the gas-absorption-induced temperature and phase modulation in a HC-PBF filled with low-concentration of C 2 H 2 in nitrogen. The PT phase modulation dynamics for different pulse duration, peak power and energy of pump beam are numerically modelled, which are supported by the experimental results obtained around the P(9) absorption line of C 2 H 2 at 1530.371 nm. Thermal conduction is identified as the main process responsible for the phase modulation dynamics. For a constant peak pump power level, the phase modulation is found to increase with pulse duration up to ~1.2 μs, while it increases with decreasing pulse duration for a constant pulse energy. It is theoretically possible to achieve ppb level detection of C 2 H 2 with ~1 m length HC-PBF and a pump beam with ~10 ns pulse duration and ~100 nJ pulse energy.

SU(p,q) coherent states and a Gaussian de Finetti theorem

NASA Astrophysics Data System (ADS)

Leverrier, Anthony

2018-04-01

We prove a generalization of the quantum de Finetti theorem when the local space is an infinite-dimensional Fock space. In particular, instead of considering the action of the permutation group on n copies of that space, we consider the action of the unitary group U(n) on the creation operators of the n modes and define a natural generalization of the symmetric subspace as the space of states invariant under unitaries in U(n). Our first result is a complete characterization of this subspace, which turns out to be spanned by a family of generalized coherent states related to the special unitary group SU(p, q) of signature (p, q). More precisely, this construction yields a unitary representation of the noncompact simple real Lie group SU(p, q). We therefore find a dual unitary representation of the pair of groups U(n) and SU(p, q) on an n(p + q)-mode Fock space. The (Gaussian) SU(p, q) coherent states resolve the identity on the symmetric subspace, which implies a Gaussian de Finetti theorem stating that tracing over a few modes of a unitary-invariant state yields a state close to a mixture of Gaussian states. As an application of this de Finetti theorem, we show that the n × n upper-left submatrix of an n × n Haar-invariant unitary matrix is close in total variation distance to a matrix of independent normal variables if n3 = O(m).

Implementation of bipartite or remote unitary gates with repeater nodes

NASA Astrophysics Data System (ADS)

Yu, Li; Nemoto, Kae

2016-08-01

We propose some protocols to implement various classes of bipartite unitary operations on two remote parties with the help of repeater nodes in-between. We also present a protocol to implement a single-qubit unitary with parameters determined by a remote party with the help of up to three repeater nodes. It is assumed that the neighboring nodes are connected by noisy photonic channels, and the local gates can be performed quite accurately, while the decoherence of memories is significant. A unitary is often a part of a larger computation or communication task in a quantum network, and to reduce the amount of decoherence in other systems of the network, we focus on the goal of saving the total time for implementing a unitary including the time for entanglement preparation. We review some previously studied protocols that implement bipartite unitaries using local operations and classical communication and prior shared entanglement, and apply them to the situation with repeater nodes without prior entanglement. We find that the protocols using piecewise entanglement between neighboring nodes often require less total time compared to preparing entanglement between the two end nodes first and then performing the previously known protocols. For a generic bipartite unitary, as the number of repeater nodes increases, the total time could approach the time cost for direct signal transfer from one end node to the other. We also prove some lower bounds of the total time when there are a small number of repeater nodes. The application to position-based cryptography is discussed.

Relative Contribution of Arms and Legs in 30 s Fully Tethered Front Crawl Swimming

PubMed Central

Morouço, Pedro G.; Marinho, Daniel A.; Izquierdo, Mikel; Neiva, Henrique; Marques, Mário C.

2015-01-01

The relative contribution of arm stroke and leg kicking to maximal fully tethered front crawl swimming performance remains to be solved. Twenty-three national level young swimmers (12 male and 11 female) randomly performed 3 bouts of 30 s fully tethered swimming (using the whole body, only the arm stroke, and only the leg kicking). A load-cell system permitted the continuous measurement of the exerted forces, and swimming velocity was calculated from the time taken to complete a 50 m front crawl swim. As expected, with no restrictions swimmers were able to exert higher forces than that using only their arm stroke or leg kicking. Estimated relative contributions of arm stroke and leg kicking were 70.3% versus 29.7% for males and 66.6% versus 33.4% for females, with 15.6% and 13.1% force deficits, respectively. To obtain higher velocities, male swimmers are highly dependent on the maximum forces they can exert with the arm stroke (r = 0.77, P < 0.01), whereas female swimmers swimming velocity is more related to whole-body mean forces (r = 0.81, P < 0.01). The obtained results point that leg kicking plays an important role over short duration high intensity bouts and that the used methodology may be useful to identify strength and/or coordination flaws. PMID:26539511

Neuromechanical simulation of the locust jump

PubMed Central

Cofer, D.; Cymbalyuk, G.; Heitler, W. J.; Edwards, D. H.

2010-01-01

The neural circuitry and biomechanics of kicking in locusts have been studied to understand their roles in the control of both kicking and jumping. It has been hypothesized that the same neural circuit and biomechanics governed both behaviors but this hypothesis was not testable with current technology. We built a neuromechanical model to test this and to gain a better understanding of the role of the semi-lunar process (SLP) in jump dynamics. The jumping and kicking behaviors of the model were tested by comparing them with a variety of published data, and were found to reproduce the results from live animals. This confirmed that the kick neural circuitry can produce the jump behavior. The SLP is a set of highly sclerotized bands of cuticle that can be bent to store energy for use during kicking and jumping. It has not been possible to directly test the effects of the SLP on jump performance because it is an integral part of the joint, and attempts to remove its influence prevent the locust from being able to jump. Simulations demonstrated that the SLP can significantly increase jump distance, power, total energy and duration of the jump impulse. In addition, the geometry of the joint enables the SLP force to assist leg flexion when the leg is flexed, and to assist extension once the leg has begun to extend. PMID:20228342

Why do female Callosobruchus maculatus kick their mates?

PubMed

van Lieshout, Emile; McNamara, Kathryn B; Simmons, Leigh W

2014-01-01

Sexual conflict is now recognised as an important driver of sexual trait evolution. However, due to their variable outcomes and effects on other fitness components, the detection of sexual conflicts on individual traits can be complicated. This difficulty is exemplified in the beetle Callosobruchus maculatus, where longer matings increase the size of nutritious ejaculates but simultaneously reduce female future receptivity. While previous studies show that females gain direct benefits from extended mating duration, females show conspicuous copulatory kicking behaviour, apparently to dislodge mating males prematurely. We explore the potential for sexual conflict by comparing several fitness components and remating propensity in pairs of full sibling females where each female mated with a male from an unrelated pair of full sibling males. For one female, matings were terminated at the onset of kicking, whereas the other's matings remained uninterrupted. While fecundity (number of eggs) was similar between treatments, uninterrupted matings enhanced adult offspring numbers and fractionally also longevity. However, females whose matings were interrupted at the onset of kicking exhibited an increased propensity to remate. Since polyandry can benefit female fitness in this species, we argue that kicking, rather than being maladaptive, may indicate that females prefer remating over increased ejaculate size. It may thus be difficult to assess the presence of sexual conflict over contested traits such as mating duration when females face a trade off between direct benefits gained from one mating and indirect benefits from additional matings.

Effects of target distance on select biomechanical parameters in taekwondo roundhouse kick.

PubMed

Falco, Coral; Molina-García, Javier; Alvarez, Octavio; Estevan, Isaac

2013-11-01

The aim of this study was to investigate the effects of target distance on temporal and impact force parameters that are important performance factors in taekwondo kicks. Forty-nine taekwondo athletes (age = 24.5 +/- 5.9 years; mass = 79.9 +/- 10.8 kg) were recruited: 13 male experts, 21 male novices, 8 female experts, and 6 female novices. Impact force, reaction time, and execution time were computed. Three-way repeated measure ANOVAs revealed significant 'distance' effect on impact force, reaction time, and execution time (p = 0.001). Comparisons between distance conditions revealed that taekwondo athletes kicked with higher impact force from short distance (17.6 +/- 7.5 N/kg) than from long distance (13.1 +/- 5.7 N/kg) (p < 0.001), had lower reaction time from short distance (498 +/- 90 ms) and normal distance (521 +/- 111 ms) than from long distance (602 +/- 121 ms) (p < 0.001), and had lower execution time from short distance (261 +/- 69 ms/m) than from normal distance (306 +/- 105 ms/m) or from long distance (350 +/- 106 ms/m) (p = 0.003 and p < 0.001, respectively). In conclusion, target distance affected the kick performance; as distance increases, impact force decreased and reaction time increased. Therefore, when reaction to a simple visual stimulus is needed, kicking from a long distance is not recommended, as longer time is required to respond.

Neuromuscular performance of Bandal Chagui: Comparison of subelite and elite taekwondo athletes.

PubMed

Moreira, Pedro Vieira Sarmet; Goethel, Márcio Fagundes; Gonçalves, Mauro

2016-10-01

With the aim of comparing kinematic and neuromuscular parameters of Bandal Chagui kicks between 7 elite and 7 subelite taekwondo athletes, nine Bandal Chaguis were performed at maximal effort in a selective reaction time design, simulating the frequency of kicks observed in taekwondo competitions. Linear and angular leg velocities were recorded through 3D motion capture system. Ground reaction forces (GRF) were evaluated by a force platform, and surface electromyographic (sEMG) signals were evaluated in the vastus lateralis, biceps femoris, rectus femoris, tensor fasciae lata, adductor magnus, gluteus maximus, gluteus medius, and gastrocnemius lateralis muscles of the kicking leg. sEMG data were processed to obtain the cocontraction indices (CI) of antagonist vs. overall (agonist and antagonist) muscle activity. CI was measured for the hip and knee, in flexion and extension, and for hip abduction. Premotor, reaction (kinetic and kinematic), and kicking times were evaluated. Timing parameters, except kinetic reaction time, were faster in elite athletes. Furthermore, CI and angular velocity during knee extension, foot and knee linear velocity, and horizontal GRF were significantly higher in elite than in subelite athletes. In conclusion, selected biomechanical parameters of Bandal Chagui appear to be useful in controlling the training status of the kick and in orienting the training goal of black belt competitors. Copyright © 2016 Elsevier Ltd. All rights reserved.

Driving qubit phase gates with sech shaped pulses

NASA Astrophysics Data System (ADS)

Long, Junling; Ku, Hsiang-Sheng; Wu, Xian; Lake, Russell; Barnes, Edwin; Economou, Sophia; Pappas, David

As shown in 1932 by Rozen and Zener, the Rabi model has a unique solution whereby, for a given pulse length or amplitude, a sech(t/sigma) shaped pulse can be used to drive complete oscillations around the Bloch sphere that are independent of detuning with only a resultant detuning-dependent phase accumulation. Using this property, single qubit phase gates and two-qubit CZ gates have been proposed. In this work we explore the effect of different drive pulse shapes, i.e. square, Gaussian, and sech, as a function of detuning for Rabi oscillations of a superconducting transmon qubit. An arbitrary, single-qubit phase gate is demonstrated with the sech(t/sigma) pulse, and full tomography is performed to extract the fidelity. This is the first step towards high fidelity, low leakage two qubit CZ gates, and illustrates the efficacy of using analytic solutions of the qubit drive prior to optimal pulse shaping.

Effect of initial phase on error in electron energy obtained using paraxial approximation for a focused laser pulse in vacuum

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

Singh, Kunwar Pal, E-mail: k-psingh@yahoo.com; Department of Physics, Shri Venkateshwara University, Gajraula, Amroha, Uttar Pradesh 244236; Arya, Rashmi

2015-09-14

We have investigated the effect of initial phase on error in electron energy obtained using paraxial approximation to study electron acceleration by a focused laser pulse in vacuum using a three dimensional test-particle simulation code. The error is obtained by comparing the energy of the electron for paraxial approximation and seventh-order correction description of the fields of Gaussian laser. The paraxial approximation predicts wrong laser divergence and wrong electron escape time from the pulse which leads to prediction of higher energy. The error shows strong phase dependence for the electrons lying along the axis of the laser for linearly polarizedmore » laser pulse. The relative error may be significant for some specific values of initial phase even at moderate values of laser spot sizes. The error does not show initial phase dependence for a circularly laser pulse.« less

Laser nitriding of iron: Nitrogen profiles and phases

NASA Astrophysics Data System (ADS)

Illgner, C.; Schaaf, P.; Lieb, K. P.; Schubert, E.; Queitsch, R.; Bergmann, H.-W.

1995-07-01

Armco iron samples were surface nitrided by irradiating them with pulses of an excimer laser in a nitrogen atmosphere. The resulting nitrogen depth profiles measured by Resonant Nuclear Reaction Analysis (RNRA) and the phase formation determined by Conversion Electron Mössbauer Spectroscopy (CEMS) were investigated as functions of energy density and the number of pulses. The nitrogen content of the samples was found to be independent of the number of pulses in a layer of 50 nm from the surface and to increase in depths exceeding 150 nm. The phase composition did not change with the number of pulses. The nitrogen content can be related to an enhanced nitrogen solubility based on high temperatures and high pressures due to the laser-induced plasma above the sample. With increasing pulse energy density, the phase composition changes towards phases with higher nitrogen contents. Nitrogen diffusion seems to be the limiting factor for the nitriding process.

Phase control in coherent population distribution in molecules

NASA Astrophysics Data System (ADS)

Datta, Avijit

2018-06-01

A chirped laser pulse transfers population from one level to another level accessible by one photon dipole transition. We have used a pair of phase-locked chirped pulses of same frequency instead of a single chirped pulse to achieve phase control over the population transfer and thus creating coherent population distribution in hydrogen molecule. Simultaneous actions of the phase controlled interference and rapid adiabatic passages due to chirped pulses lead to the control in population transfer from the ground X(v = 0, j = 0) level to the C(v = 2, j = 1) level. We have extended this two-level system to a three-level 1 + 1 ladder system for population transfer from the X level to the J(v = 2, j = 2) level via the C intermediate level using two pairs of phase-locked laser chirped pulses and have achieved laudable control over the coherent population distribution.

Effect of laser pulse shaping parameters on the fidelity of quantum logic gates.

PubMed

Zaari, Ryan R; Brown, Alex

2012-09-14

The effect of varying parameters specific to laser pulse shaping instruments on resulting fidelities for the ACNOT(1), NOT(2), and Hadamard(2) quantum logic gates are studied for the diatomic molecule (12)C(16)O. These parameters include varying the frequency resolution, adjusting the number of frequency components and also varying the amplitude and phase at each frequency component. A time domain analytic form of the original discretized frequency domain laser pulse function is derived, providing a useful means to infer the resulting pulse shape through variations to the aforementioned parameters. We show that amplitude variation at each frequency component is a crucial requirement for optimal laser pulse shaping, whereas phase variation provides minimal contribution. We also show that high fidelity laser pulses are dependent upon the frequency resolution and increasing the number of frequency components provides only a small incremental improvement to quantum gate fidelity. Analysis through use of the pulse area theorem confirms the resulting population dynamics for one or two frequency high fidelity laser pulses and implies similar dynamics for more complex laser pulse shapes. The ability to produce high fidelity laser pulses that provide both population control and global phase alignment is attributed greatly to the natural evolution phase alignment of the qubits involved within the quantum logic gate operation.

Quantum mechanics on periodic and non-periodic lattices and almost unitary Schwinger operators

NASA Astrophysics Data System (ADS)

Arik, Metin; Ildes, Medine

2018-05-01

In this work, we uncover the mathematical structure of the Schwinger algebra and introduce almost unitary Schwinger operators which are derived by considering translation operators on a finite lattice. We calculate mathematical relations between these algebras and show that the almost unitary Schwinger operators are equivalent to the Schwinger algebra. We introduce new representations for MN(C) in terms of these algebras.

UAS Integration in the NAS Project Test Site Kick-off Meeting

NASA Technical Reports Server (NTRS)

Kopardekar, Parimal; Witzberger, Kevin; Hackenberg, Davis L.; Murphy, Jim

2015-01-01

This briefing was presented during the Test Site Kick Off Meeting to discuss the contract awards for Task 1 and Task 2. This briefing covered a high level overview for contract deliverables, Task 1 - UAS Traffic Management and Task 2, Live Virtual Constructive Distributed Environment.

Kick processes in the merger of two colliding black holes

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

Aranha, R. F.; Soares, I. Damiao; Tonini, E. V.

2010-11-15

We examine numerically the process of momentum extraction by gravitational waves in the merger of two colliding black holes, in the realm of Robinson-Trautman spacetimes. The initial data have already a common horizon so that the evolution covers the post-merger phase up to the final configuration of the remnant black hole. The analysis of the momentum flux carried out by gravitational waves indicates that two distinct regimes are present in the post-merger phase: (i) an initial accelerated regime, followed by (ii) a deceleration regime in which the deceleration increases rapidly towards a maximum and then decreases to zero, when themore » gravitational wave emission ceases. The analysis is based on the Bondi-Sachs conservation law for the total momentum of the system. We obtain the total kick velocity V{sub k} imparted on the merged black hole during the accelerated regime (i) and the total antikick velocity V{sub ak} during the decelerated regime (ii), by evaluating the impulse of the gravitational wave flux during both regimes. The distributions of both V{sub k} and V{sub ak} as a function of the symmetric mass ratio {eta} satisfy a simple {eta}-scaling law motivated by post-Newtonian analytical estimates. In the {eta}-scaling formula the Newtonian factor is dominant in the decelerated regime, that generates V{sub ak}, contrary to the behavior in the initial accelerated regime. For an initial infalling velocity v/c{approx_equal}0.462 of each individual black hole we obtain a maximum kick V{sub k{approx_equal}}6.4 km/s at {eta}{approx_equal}0.209, and a maximum antikick V{sub ak{approx_equal}}109 km/s at {eta}{approx_equal}0.205. The net antikick velocity (V{sub ak}-V{sub k}) also satisfies a similar {eta}-scaling law with a maximum approximately 102 km/s also at {eta}{approx_equal}0.205, qualitatively consistent with results from numerical relativity simulations, and post-Newtonian evaluations of binary black hole inspirals. For larger values of the initial data parameter v/c substantial larger values of the net antikick velocity are obtained. Based on the several velocity variables obtained, we discuss a possible definition of the center-of-mass motion of the merged system.« less

ac Stark-mediated quantum control with femtosecond two-color laser pulses

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

Serrat, Carles

2005-11-15

A critical dependence of the quantum interference on the optical Stark spectral shift produced when two-color laser pulses interact with a two-level medium is observed. The four-wave mixing of two ultrashort phase-locked {omega}-3{omega} laser pulses propagating coherently in a two-level system depends on the pulses' relative phase. The phase dominating the efficiency of the coupling to the anti-Stokes Raman component is found to be determined by the sign of the total ac Stark shift induced in the system, in such a way that the phase sensitivity disappears precisely where the ac Stark effect due to both pulses is compensated. Amore » coherent control scheme based on this phenomenon can be contemplated as the basis for nonlinear optical spectroscopy techniques.« less

Phase and frequency structure of superradiance pulses generated by relativistic Ka-band backward-wave oscillator

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

Rostov, V. V.; Romanchenko, I. V.; Elchaninov, A. A.

2016-08-15

Phase and frequency stability of electromagnetic oscillations in sub-gigawatt superradiance (SR) pulses generated by an extensive slow-wave structure of a relativistic Ka-band backward-wave oscillator were experimentally investigated. Data on the frequency tuning and radiation phase stability of SR pulses with a variation of the energy and current of electron beam were obtained.

Phase control of attosecond pulses in a train

NASA Astrophysics Data System (ADS)

Guo, Chen; Harth, Anne; Carlström, Stefanos; Cheng, Yu-Chen; Mikaelsson, Sara; Mårsell, Erik; Heyl, Christoph; Miranda, Miguel; Gisselbrecht, Mathieu; Gaarde, Mette B.; Schafer, Kenneth J.; Mikkelsen, Anders; Mauritsson, Johan; Arnold, Cord L.; L'Huillier, Anne

2018-02-01

Ultrafast processes in matter can be captured and even controlled by using sequences of few-cycle optical pulses, which need to be well characterized, both in amplitude and phase. The same degree of control has not yet been achieved for few-cycle extreme ultraviolet pulses generated by high-order harmonic generation (HHG) in gases, with duration in the attosecond range. Here, we show that by varying the spectral phase and carrier-envelope phase (CEP) of a high-repetition rate laser, using dispersion in glass, we achieve a high degree of control of the relative phase and CEP between consecutive attosecond pulses. The experimental results are supported by a detailed theoretical analysis based upon the semi-classical three-step model for HHG.

Accurate and Robust Unitary Transformations of a High-Dimensional Quantum System

NASA Astrophysics Data System (ADS)

Anderson, B. E.; Sosa-Martinez, H.; Riofrío, C. A.; Deutsch, Ivan H.; Jessen, Poul S.

2015-06-01

Unitary transformations are the most general input-output maps available in closed quantum systems. Good control protocols have been developed for qubits, but questions remain about the use of optimal control theory to design unitary maps in high-dimensional Hilbert spaces, and about the feasibility of their robust implementation in the laboratory. Here we design and implement unitary maps in a 16-dimensional Hilbert space associated with the 6 S1 /2 ground state of 133Cs, achieving fidelities >0.98 with built-in robustness to static and dynamic perturbations. Our work has relevance for quantum information processing and provides a template for similar advances on other physical platforms.

Natural resource theory of unitary taxation

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

Johnston, J.L.; Reynolds, A.

1985-01-01

Empirical evidence supports the tentative hypothesis that unitary taxation encourages natural resource recovery in states well endowed with timber, fuels, and nonfuel minerals. Consequently, if combined apportionment is a stable institution in any state, it will remain so while extractive industries, with higher upstream than downstream profitability, continue to dominate the state's economy. Over time, however, nonproducing states will abandon unitary taxation to prevent integrated firms from disinvesting within their borders and expanding operations in states with a hospitable investment climate. Since states, like firms, must compete with one another, unitary taxation will become less important as state economies becomemore » less dependent on the recovery of natural resources. 43 references, 1 figure, 4 tables.« less

Analytical treatment of self-phase-modulation beyond the slowly varying envelope approximation

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

Syrchin, M.S.; Zheltikov, A.M.; International Laser Center, M.V. Lomonosov Moscow State University, 119899 Moscow

Analytical treatment of the self-phase-modulation of an ultrashort light pulse is extended beyond the slowly varying envelope approximation. The resulting wave equation is modified to include corrections to self-phase-modulation due to higher-order spatial and temporal derivatives. Analytical solutions are found in the limiting regimes of high nonlinearities and very short pulses. Our results reveal features that can significantly impact both pulse shape and the evolution of the phase.

Carrier-envelope phase control of femtosecond mode-locked lasers and direct optical frequency synthesis

PubMed

Jones; Diddams; Ranka; Stentz; Windeler; Hall; Cundiff

2000-04-28

We stabilized the carrier-envelope phase of the pulses emitted by a femtosecond mode-locked laser by using the powerful tools of frequency-domain laser stabilization. We confirmed control of the pulse-to-pulse carrier-envelope phase using temporal cross correlation. This phase stabilization locks the absolute frequencies emitted by the laser, which we used to perform absolute optical frequency measurements that were directly referenced to a stable microwave clock.

Frequency-domain nonlinear optics in two-dimensionally patterned quasi-phase-matching media.

PubMed

Phillips, C R; Mayer, B W; Gallmann, L; Keller, U

2016-07-11

Advances in the amplification and manipulation of ultrashort laser pulses have led to revolutions in several areas. Examples include chirped pulse amplification for generating high peak-power lasers, power-scalable amplification techniques, pulse shaping via modulation of spatially-dispersed laser pulses, and efficient frequency-mixing in quasi-phase-matched nonlinear crystals to access new spectral regions. In this work, we introduce and demonstrate a new platform for nonlinear optics which has the potential to combine these separate functionalities (pulse amplification, frequency transfer, and pulse shaping) into a single monolithic device that is bandwidth- and power-scalable. The approach is based on two-dimensional (2D) patterning of quasi-phase-matching (QPM) gratings combined with optical parametric interactions involving spatially dispersed laser pulses. Our proof of principle experiment demonstrates this technique via mid-infrared optical parametric chirped pulse amplification of few-cycle pulses. Additionally, we present a detailed theoretical and numerical analysis of such 2D-QPM devices and how they can be designed.

Few-cycle carrier envelope phase-dependent stereo detection of electrons.

PubMed

Verhoef, Aart J; Fernández, Alma; Lezius, Matthias; O'Keeffe, Kevin; Uiberacker, Matthias; Krausz, Ferenc

2006-12-01

The spatial distribution of electrons emitted from atoms by few-cycle optical fields is known to be dependent on the carrier envelope phase, i.e., the phase of the field with respect to the pulse envelope. With respect to Paulus et al. [Phys. Rev. Lett.91, 253004 (2003)] we propose a greatly simplified device to measure and control the carrier envelope phase of few-cycle pulses with an accuracy of better than pi/10 based on this principle. We compared different schemes to control the carrier envelope phase of our pulses.

Tracing the phase of focused broadband laser pulses

NASA Astrophysics Data System (ADS)

Hoff, Dominik; Krüger, Michael; Maisenbacher, Lothar; Sayler, A. M.; Paulus, Gerhard G.; Hommelhoff, Peter

2017-10-01

Precise knowledge of the behaviour of the phase of light in a focused beam is fundamental to understanding and controlling laser-driven processes. More than a hundred years ago, an axial phase anomaly for focused monochromatic light beams was discovered and is now commonly known as the Gouy phase. Recent theoretical work has brought into question the validity of applying this monochromatic phase formulation to the broadband pulses becoming ubiquitous today. Based on electron backscattering at sharp nanometre-scale metal tips, a method is available to measure light fields with sub-wavelength spatial resolution and sub-optical-cycle time resolution. Here we report such a direct, three-dimensional measurement of the spatial dependence of the optical phase of a focused, 4-fs, near-infrared pulsed laser beam. The observed optical phase deviates substantially from the monochromatic Gouy phase--exhibiting a much more complex spatial dependence, both along the propagation axis and in the radial direction. In our measurements, these significant deviations are the rule and not the exception for focused, broadband laser pulses. Therefore, we expect wide ramifications for all broadband laser-matter interactions, such as in high-harmonic and attosecond pulse generation, femtochemistry, ophthalmological optical coherence tomography and light-wave electronics.

Instrument to synchronize Thomson scattering diagnostic measurements with MHD acitivity in a tokamak

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

Wintenberg, A.L.

1985-04-01

An instrument to synchronize the firing of a ruby laser for a Thomson scattering diagnostic with plasma oscillations was designed, developed, and evaluated. The instrument will fire the laser at a user-selected phase of an input sine or sawtooth wave with an accuracy of +-15/sup 0/. Allowable frequencies range from 20 to 500 Hz for a sawtooth and from 1 to 30 kHz for a sine wave. The instrument also allows synchronization with a sine wave to be enabled by a preselected sawtooth phase. The instrument uses analog signal processing circuits to separate the signal components, remove unwanted components, andmore » produce zero-phase synchronization pulses. The instrument measures the period between zero-phase pulses in order to produce phase synchronization pulses delayed a fraction of the period from the zero-phase pulses. The laser is fired by the phase synchronization pulse. Unwanted signal components are attenuated by bandpass filters. A digitally controlled self-adjusting bandpass filter for sine processing. The instrument was used to investigate the variation of the electron temperature profile with the phase of the x-ray signal from an Impurity Studies Experiment (ISX-B) plasma exhibiting magnetohydrodynamic (MHD) activity.« less

Importance of counter-rotating coupling in the superfluid-to-Mott-insulator quantum phase transition of light in the Jaynes-Cummings lattice

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

Zheng Hang; Takada, Yasutami

2011-10-15

The quantum phase transition between Mott insulator and superfluid is studied in the two-dimensional Jaynes-Cummings square lattice in which the counter-rotating coupling (CRC) is included. Both the ground state and the spectra of low-lying excitations are obtained with use of a sophisticated unitary transformation. This CRC is shown not only to induce a long-range interaction between cavities, favoring the long-range superfluid order, but also to break the conservation of local polariton number at each site, leading to the absence of the Mott lobes in the phase diagram, in sharp contrast with the case without the CRC as well as thatmore » of the Bose-Hubbard model.« less

Time-invariant PT product and phase locking in PT -symmetric lattice models

NASA Astrophysics Data System (ADS)

Joglekar, Yogesh N.; Onanga, Franck Assogba; Harter, Andrew K.

2018-01-01

Over the past decade, non-Hermitian, PT -symmetric Hamiltonians have been investigated as candidates for both a fundamental, unitary, quantum theory and open systems with a nonunitary time evolution. In this paper, we investigate the implications of the former approach in the context of the latter. Motivated by the invariance of the PT (inner) product under time evolution, we discuss the dynamics of wave-function phases in a wide range of PT -symmetric lattice models. In particular, we numerically show that, starting with a random initial state, a universal, gain-site location dependent locking between wave-function phases at adjacent sites occurs in the PT -symmetry-broken region. Our results pave the way towards understanding the physically observable implications of time invariants in the nonunitary dynamics produced by PT -symmetric Hamiltonians.

Entanglement and Berry Phase in a Parameterized Three-Qubit System

NASA Astrophysics Data System (ADS)

Shao, Wenyi; Du, Yangyang; Yang, Qi; Wang, Gangcheng; Sun, Chunfang; Xue, Kang

2017-03-01

In this paper, we construct a parameterized form of unitary breve {R}_{123}(θ 1,θ 2,φ) matrix through the Yang-Baxterization method. Acting such matrix on three-qubit natural basis as a quantum gate, we can obtain a set of entangled states, which possess the same entanglement value depending on the parameters 𝜃 1 and 𝜃 2. Particularly, such entangled states can produce a set of maximally entangled bases Greenberger-Horne-Zeilinger (GHZ) states with respect to 𝜃 1 = 𝜃 2 = π/2. Choosing a useful Hamiltonian, one can study the evolution of the eigenstates and investigate the result of Berry phase. It is not difficult to find that the Berry phase for this new three-qubit system consistent with the solid angle on the Bloch sphere.

Unitary reconstruction of secret for stabilizer-based quantum secret sharing

NASA Astrophysics Data System (ADS)

Matsumoto, Ryutaroh

2017-08-01

We propose a unitary procedure to reconstruct quantum secret for a quantum secret sharing scheme constructed from stabilizer quantum error-correcting codes. Erasure correcting procedures for stabilizer codes need to add missing shares for reconstruction of quantum secret, while unitary reconstruction procedures for certain class of quantum secret sharing are known to work without adding missing shares. The proposed procedure also works without adding missing shares.

Minimal unitary representation of SO∗(8)=SO(6,2) and its SU(2) deformations as massless 6D conformal fields and their supersymmetric extensions

NASA Astrophysics Data System (ADS)

Fernando, Sudarshan; Günaydin, Murat

2010-12-01

We study the minimal unitary representation (minrep) of SO(6,2) over an Hilbert space of functions of five variables, obtained by quantizing its quasiconformal realization. The minrep of SO(6,2), which coincides with the minrep of SO(8) similarly constructed, corresponds to a massless conformal scalar field in six spacetime dimensions. There exists a family of "deformations" of the minrep of SO(8) labeled by the spin t of an SU(2 subgroup of the little group SO(4) of lightlike vectors. These deformations labeled by t are positive energy unitary irreducible representations of SO(8) that describe massless conformal fields in six dimensions. The SU(2 spin t is the six-dimensional counterpart of U(1) deformations of the minrep of 4D conformal group SU(2,2) labeled by helicity. We also construct the supersymmetric extensions of the minimal unitary representation of SO(8) to minimal unitary representations of OSp(8|2N) that describe massless six-dimensional conformal supermultiplets. The minimal unitary supermultiplet of OSp(8|4) is the massless supermultiplet of (2,0) conformal field theory that is believed to be dual to M-theory on AdS×S.

Computational Modeling of the Dolphin Kick in Competitive Swimming

NASA Astrophysics Data System (ADS)

Loebbeck, A.; Mark, R.; Bhanot, G.

2005-11-01

Numerical simulations are being used to study the fluid dynamics of the dolphin kick in competitive swimming. This stroke is performed underwater after starts and turns and involves an undulatory motion of the body. Highly detailed laser body scans of elite swimmers are used and the kinematics of the dolphin kick is recreated from videos of Olympic level swimmers. We employ a parallelized immersed boundary method to simulate the flow associated with this stroke in all its complexity. The simulations provide a first of its kind glimpse of the fluid and vortex dynamics associated with this stroke and hydrodynamic force computations allow us to gain a better understanding of the thrust producing mechanisms.

Identification and analysis of unitary pseudogenes: historic and contemporary gene losses in humans and other primates

PubMed Central

2010-01-01

Background Unitary pseudogenes are a class of unprocessed pseudogenes without functioning counterparts in the genome. They constitute only a small fraction of annotated pseudogenes in the human genome. However, as they represent distinct functional losses over time, they shed light on the unique features of humans in primate evolution. Results We have developed a pipeline to detect human unitary pseudogenes through analyzing the global inventory of orthologs between the human genome and its mammalian relatives. We focus on gene losses along the human lineage after the divergence from rodents about 75 million years ago. In total, we identify 76 unitary pseudogenes, including previously annotated ones, and many novel ones. By comparing each of these to its functioning ortholog in other mammals, we can approximately date the creation of each unitary pseudogene (that is, the gene 'death date') and show that for our group of 76, the functional genes appear to be disabled at a fairly uniform rate throughout primate evolution - not all at once, correlated, for instance, with the 'Alu burst'. Furthermore, we identify 11 unitary pseudogenes that are polymorphic - that is, they have both nonfunctional and functional alleles currently segregating in the human population. Comparing them with their orthologs in other primates, we find that two of them are in fact pseudogenes in non-human primates, suggesting that they represent cases of a gene being resurrected in the human lineage. Conclusions This analysis of unitary pseudogenes provides insights into the evolutionary constraints faced by different organisms and the timescales of functional gene loss in humans. PMID:20210993

Femtosecond pulse shaping using the geometric phase.

PubMed

Gökce, Bilal; Li, Yanming; Escuti, Michael J; Gundogdu, Kenan

2014-03-15

We demonstrate a femtosecond pulse shaper that utilizes polarization gratings to manipulate the geometric phase of an optical pulse. This unique approach enables circular polarization-dependent shaping of femtosecond pulses. As a result, it is possible to create coherent pulse pairs with orthogonal polarizations in a 4f pulse shaper setup, something until now that, to our knowledge, was only achieved via much more complex configurations. This approach could be used to greatly simplify and enhance the functionality of multidimensional spectroscopy and coherent control experiments, in which multiple coherent pulses are used to manipulate quantum states in materials of interest.

Performance of large aperture tapered fiber phase conjugate mirror with high pulse energy and 1-kHz repetition rate.

PubMed

Zhao, Zhigang; Dong, Yantao; Pan, Sunqiang; Liu, Chong; Chen, Jun; Tong, Lixin; Gao, Qingsong; Tang, Chun

2012-01-16

A large aperture fused silica tapered fiber phase conjugate mirror is presented with a maximum 70% stimulated Brillouin scattering (SBS) reflectivity, which is obtained with 1 kHz repetition rate, 15 ns pulse width and 38 mJ input pulse energy. To the best of our knowledge, this is the highest SBS reflectivity ever reported by using optical fiber as a phase conjugate mirror for such high pulse repetition rate (1 kHz) and several tens of millijoule (mJ) input pulse energy. The influences of fiber end surface quality and pump pulse widths on SBS reflectivity are investigated experimentally. The results show that finer fiber end surface quality and longer input pulse widths are preferred for obtaining higher SBS reflectivity with higher input pulse energy. Double passing amplification experiments are also performed. 52 mJ pulse energy is achieved at 1 kHz repetition rate, with a reflected SBS pulse width of 1.5 ns and a M(2) factor of 2.3. The corresponding peak power reaches 34.6 MW. Obvious beam quality improvement is observed.

Repetitive transcranial magnetic stimulator with controllable pulse parameters

NASA Astrophysics Data System (ADS)

Peterchev, Angel V.; Murphy, David L.; Lisanby, Sarah H.

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Single-shot high-resolution characterization of optical pulses by spectral phase diversity

DOE PAGES

Dorrer, C.; Waxer, L. J.; Kalb, A.; ...

2015-12-15

The concept of spectral phase diversity is proposed and applied to the temporal characterization of optical pulses. The experimental trace is composed of the measured power of a plurality of ancillary optical pulses derived from the pulse under test by adding known amounts of chromatic dispersion. The spectral phase of the pulse under test is retrieved by minimizing the error between the experimental trace and a trace calculated from the optical spectrum using the known diagnostic parameters. An assembly composed of splitters and dispersive delay fibers has been used to generate 64 ancillary pulses whose instantaneous power can be detectedmore » in a single shot with a high-bandwidth photodiode and oscilloscope. Pulse-shape reconstruction for pulses shorter than the photodetection impulse response has been demonstrated.The diagnostic is experimentally shown to accurately characterize pulses from a chirped-pulse–amplification system when its stretcher is detuned from the position for optimal recompression. As a result, various investigations of the performance with respect to the number of ancillary pulses and the range of chromatic dispersion generated in the diagnostic are presented.« less

Repetitive transcranial magnetic stimulator with controllable pulse parameters.

PubMed

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2011-06-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10-310 µs and positive/negative phase amplitude ratio of 1-56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation up to 82% and 57% and decreases coil heating up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications and could lead to clinical applications with potentially enhanced potency.

Single-shot high-resolution characterization of optical pulses by spectral phase diversity

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

Dorrer, C.; Waxer, L. J.; Kalb, A.

The concept of spectral phase diversity is proposed and applied to the temporal characterization of optical pulses. The experimental trace is composed of the measured power of a plurality of ancillary optical pulses derived from the pulse under test by adding known amounts of chromatic dispersion. The spectral phase of the pulse under test is retrieved by minimizing the error between the experimental trace and a trace calculated from the optical spectrum using the known diagnostic parameters. An assembly composed of splitters and dispersive delay fibers has been used to generate 64 ancillary pulses whose instantaneous power can be detectedmore » in a single shot with a high-bandwidth photodiode and oscilloscope. Pulse-shape reconstruction for pulses shorter than the photodetection impulse response has been demonstrated.The diagnostic is experimentally shown to accurately characterize pulses from a chirped-pulse–amplification system when its stretcher is detuned from the position for optimal recompression. As a result, various investigations of the performance with respect to the number of ancillary pulses and the range of chromatic dispersion generated in the diagnostic are presented.« less

Effect of the carrier-envelope phase of the driving laser field on the high-order harmonic attosecond pulse

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

Zeng Zhinan; Li Ruxin; Yu Wei

2003-01-01

The effect of the carrier-envelope phase of a few-cycle driving laser field on the generation and measurement of high-order harmonic attosecond pulses is investigated theoretically. We find that the position of the generated attosecond soft-x-ray pulse in the cutoff region is locked to the oscillation of the driving laser field, but not to the envelope of the laser pulse. This property ensures the success of the width measurement of an attosecond soft-x-ray pulse based on the cross correlation between the attosecond pulse and its driving laser pulse [M. Hentschel et al., Nature (London) 414, 509 (2001)]. However, there still existsmore » a timing jitter of the order of tens of attoseconds between the attosecond pulse and its driving laser field. We also propose a method to detect the carrier-envelope phase of the driving laser field by measuring the spatial distribution of the photoelectrons induced by the attosecond soft-x-ray pulse and its driving laser pulse.« less

Numerical tsunami hazard assessment of the submarine volcano Kick 'em Jenny in high resolution are

NASA Astrophysics Data System (ADS)

Dondin, Frédéric; Dorville, Jean-Francois Marc; Robertson, Richard E. A.

2016-04-01

Landslide-generated tsunami are infrequent phenomena that can be potentially highly hazardous for population located in the near-field domain of the source. The Lesser Antilles volcanic arc is a curved 800 km chain of volcanic islands. At least 53 flank collapse episodes have been recognized along the arc. Several of these collapses have been associated with underwater voluminous deposits (volume > 1 km3). Due to their momentum these events were likely capable of generating regional tsunami. However no clear field evidence of tsunami associated with these voluminous events have been reported but the occurrence of such an episode nowadays would certainly have catastrophic consequences. Kick 'em Jenny (KeJ) is the only active submarine volcano of the Lesser Antilles Arc (LAA), with a current edifice volume estimated to 1.5 km3. It is the southernmost edifice of the LAA with recognized associated volcanic landslide deposits. The volcano appears to have undergone three episodes of flank failure. Numerical simulations of one of these episodes associated with a collapse volume of ca. 4.4 km3 and considering a single pulse collapse revealed that this episode would have produced a regional tsunami with amplitude of 30 m. In the present study we applied a detailed hazard assessment on KeJ submarine volcano (KeJ) form its collapse to its waves impact on high resolution coastal area of selected island of the LAA in order to highlight needs to improve alert system and risk mitigation. We present the assessment process of tsunami hazard related to shoreline surface elevation (i.e. run-up) and flood dynamic (i.e. duration, height, speed...) at the coast of LAA island in the case of a potential flank collapse scenario at KeJ. After quantification of potential initial volumes of collapse material using relative slope instability analysis (RSIA, VolcanoFit 2.0 & SSAP 4.5) based on seven geomechanical models, the tsunami source have been simulate by St-Venant equations-based code (VolcFlow-Matlab). The wave have been propagated on the coastal area of two island with high resolution bathymetry (Litto3D). Keywords - Volcano edifice stability, Collapse volume estimate, Tsunami impact, Kick 'em Jenny, wave propagation, Lesser Antilles, High resolution bathymetry

The Association between Motor Skill Competence and Physical Fitness in Young Adults

ERIC Educational Resources Information Center

Stodden, David; Langendorfer, Stephen; Roberton, Mary Ann

2009-01-01

We examined the relationship between competence in three fundamental motor skills (throwing, kicking, and jumping) and six measures of health-related physical fitness in young adults (ages 18-25). We assessed motor skill competence using product scores of maximum kicking and throwing speed and maximum jumping distance. A factor analysis indicated…

Kick the Ball or Kicked the Ball? Perception of the Past Morpheme "-ed" by Second Language Learners

ERIC Educational Resources Information Center

Bell, Philippa; Trofimovich, Pavel; Collins, Laura

2015-01-01

Explanations for the well-documented second language (L2) learning challenge of the English regular past include verb semantics (Bardovi-Harlig, 2000), phonetic properties (Goad, White, & Steele, 2003), and frequency factors (Collins, Trofimovich, White, Cardoso, & Horst, 2009). Difficulty perceiving past-tense morphology (i.e., hearing…

Wave-optics modeling of the optical-transport line for passive optical stochastic cooling

NASA Astrophysics Data System (ADS)

Andorf, M. B.; Lebedev, V. A.; Piot, P.; Ruan, J.

2018-03-01

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream "pickup" undulator to the downstream "kicker" undulator. In this paper, we present simulation results using wave-optics calculation carried out with the SYNCHROTRON RADIATION WORKSHOP (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrable Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.

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

Andorf, M. B.; Lebedev, V. A.; Piot, P.

Optical stochastic cooling (OSC) is expected to enable fast cooling of dense particle beams. Transition from microwave to optical frequencies enables an achievement of stochastic cooling rates which are orders of magnitude higher than ones achievable with the classical microwave based stochastic cooling systems. A subsystemcritical to the OSC scheme is the focusing optics used to image radiation from the upstream “pickup” undulator to the downstream “kicker” undulator. In this paper, we present simulation results using wave-optics calculation carried out with the Synchrotron Radiation Workshop (SRW). Our simulations are performed in support to a proof-of-principle experiment planned at the Integrablemore » Optics Test Accelerator (IOTA) at Fermilab. The calculations provide an estimate of the energy kick received by a 100-MeV electron as it propagates in the kicker undulator and interacts with the electromagnetic pulse it radiated at an earlier time while traveling through the pickup undulator.« less

Black hole/pulsar binaries in the Galaxy

NASA Astrophysics Data System (ADS)

Shao, Yong; Li, Xiang-Dong

2018-06-01

We have performed population synthesis calculation on the formation of binaries containing a black hole (BH) and a neutron star (NS) in the Galactic disc. Some of important input parameters, especially for the treatment of common envelope evolution, are updated in the calculation. We have discussed the uncertainties from the star formation rate of the Galaxy and the velocity distribution of NS kicks on the birthrate (˜ 0.6-13 M yr^{-1}) of BH/NS binaries. From incident BH/NS binaries, by modelling the orbital evolution due to gravitational wave radiation and the NS evolution as radio pulsars, we obtain the distributions of the observable parameters such as the orbital period, eccentricity, and pulse period of the BH/pulsar binaries. We estimate that there may be ˜3-80 BH/pulsar binaries in the Galactic disc and around 10 per cent of them could be detected by the Five-hundred-metre Aperture Spherical radio Telescope.

Biomechanical analysis of three tennis serve types using a markerless system.

PubMed

Abrams, Geoffrey D; Harris, Alex H S; Andriacchi, Thomas P; Safran, Marc R

2014-02-01

The tennis serve is commonly associated with musculoskeletal injury. Advanced players are able to hit multiple serve types with different types of spin. No investigation has characterised the kinematics of all three serve types for the upper extremity and back. Seven NCAA Division I male tennis players performed three successful flat, kick and slice serves. Serves were recorded using an eight camera markerless motion capture system. Laser scanning was utilised to accurately collect body dimensions and data were computed using inverse kinematic methods. There was no significant difference in maximum back extension angle for the flat, kick or slice serves. The kick serve had a higher force magnitude at the back than the flat and slice as well as larger posteriorly directed shoulder forces. The flat serve had significantly greater maximum shoulder internal rotation velocity versus the slice serve. Force and torque magnitudes at the elbow and wrist were not significantly different between the serves. The kick serve places higher physical demands on the back and shoulder while the slice serve demonstrated lower overall kinetic forces. This information may have injury prevention and rehabilitation implications.

A computational method for analysis of underwater dolphin kick hydrodynamics in human swimming.

PubMed

von Loebbecke, Alfred; Mittal, Rajat; Mark, Russell; Hahn, James

2009-03-01

We present a new method that combines the use of laser body scans, underwater video footage, software-based animation, and a fully unsteady computational fluid dynamics technique to simulate and examine the hydrodynamics of the dolphin kick. The focus of the current work is to model this particular stroke in all its complexity with minimal ad-hoc assumptions or simplifications. Simulations of one female and one male swimmer (both at about 1.7 m beneath the water surface) at velocities of 0.95 and 1.31 m/s and Strouhal numbers of 1.21 and 1.06 respectively are presented. Vorticity and fluid velocity profiles in the wake are examined in detail for both swimmers. A three-dimensional vortex ring is clearly identified in the wake for one of the cases and a two-dimensional slice through the ring corroborates previous experiments of Miwa et al. (2006). We also find that most of the thrust is produced by the feet and in both cases the down-kick produces much larger thrust than the up-kick.

Narrowband supercontinuum control using phase shaping

NASA Astrophysics Data System (ADS)

Austin, Dane R.; Bolger, Jeremy A.; de Sterke, C. Martijn; Eggleton, Benjamin J.; Brown, Thomas G.

2006-12-01

We study theoretically, numerically and experimentally the effect of self-phase modulation of ultrashort pulses with spectrally narrow phase features. We show that spectral enhancement and depletion is caused by changing the relative phase between the initial field and the nonlinearly generated components. Our theoretical results explain observations of supercontinuum enhancement by fiber Bragg gratings, and predict similar enhancements for spectrally shaped pulses in uniform fiber. As proof of principle, we demonstrate this effect in the laboratory using a femtosecond pulse shaper.

Equilibrium and Non-Equilibrium Condensation Phenomena in Tuneable 3D and 2D Bose Gases

DTIC Science & Technology

2016-04-01

condensed gas " which remains condensed above the expected critical temperature, and performed one of the first studies of the strongly-interacting "unitary...34 Bose gas . With the 2d harmonic trap we showed how the interaction-driven BKT phase is connected with purely statistical theory, and with the 3d...box trap we created the world’s first atomic BEC in a quasi-uniform potential. 15. SUBJECT TERMS EOARD, Bose gas , ultracold, condensation, equilibrium

Carrier-Envelope Phase Effects in Plasma-Based Electron Acceleration with Few-Cycle Laser Pulses

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

Nerush, E. N.; Kostyukov, I. Yu.

2009-07-17

Carrier-envelope phase effects during the interaction of relativistically intense few-cycle laser pulses with a plasma are studied in the 'bubble' regime when an electron cavity (bubble) is formed behind the pulse. We show that for few-cycle laser pulses the cavity shape becomes asymmetric and depends strongly on the carrier-envelope phase. The carrier-envelope phase varies when the laser pulse propagates in plasma, which causes transverse oscillations of the cavity. Furthermore, the beam of electrons trapped by the cavity becomes modulated in the polarization plane. To describe these effects we derive an analytical model extended beyond the ponderomotive approximation. The degree ofmore » plasma cavity asymmetry as a function of the laser-plasma parameters is calculated. The obtained results are verified by particle-in-cell simulations.« less

Why Do Female Callosobruchus maculatus Kick Their Mates?

PubMed Central

van Lieshout, Emile; McNamara, Kathryn B.; Simmons, Leigh W.

2014-01-01

Sexual conflict is now recognised as an important driver of sexual trait evolution. However, due to their variable outcomes and effects on other fitness components, the detection of sexual conflicts on individual traits can be complicated. This difficulty is exemplified in the beetle Callosobruchus maculatus, where longer matings increase the size of nutritious ejaculates but simultaneously reduce female future receptivity. While previous studies show that females gain direct benefits from extended mating duration, females show conspicuous copulatory kicking behaviour, apparently to dislodge mating males prematurely. We explore the potential for sexual conflict by comparing several fitness components and remating propensity in pairs of full sibling females where each female mated with a male from an unrelated pair of full sibling males. For one female, matings were terminated at the onset of kicking, whereas the other’s matings remained uninterrupted. While fecundity (number of eggs) was similar between treatments, uninterrupted matings enhanced adult offspring numbers and fractionally also longevity. However, females whose matings were interrupted at the onset of kicking exhibited an increased propensity to remate. Since polyandry can benefit female fitness in this species, we argue that kicking, rather than being maladaptive, may indicate that females prefer remating over increased ejaculate size. It may thus be difficult to assess the presence of sexual conflict over contested traits such as mating duration when females face a trade off between direct benefits gained from one mating and indirect benefits from additional matings. PMID:24752530

Nanosecond bipolar pulse generators for bioelectrics.

PubMed

Xiao, Shu; Zhou, Chunrong; Yang, Enbo; Rajulapati, Sambasiva R

2018-04-26

Biological effects caused by a nanosecond pulse, such as cell membrane permeabilization, peripheral nerve excitation and cell blebbing, can be reduced or cancelled by applying another pulse of reversed polarity. Depending on the degree of cancellation, the pulse interval of these two pulses can be as long as dozens of microseconds. The cancellation effect diminishes as the pulse duration increases. To study the cancellation effect and potentially utilize it in electrotherapy, nanosecond bipolar pulse generators must be made available. An overview of the generators is given in this paper. A pulse forming line (PFL) that is matched at one end and shorted at the other end allows a bipolar pulse to be produced, but no delay can be inserted between the phases. Another generator employs a combination of a resistor, an inductor and a capacitor to form an RLC resonant circuit so that a bipolar pulse with a decaying magnitude can be generated. A third generator is a converter, which converts an existing unipolar pulse to a bipolar pulse. This is done by inserting an inductor in a transmission line. The first phase of the bipolar pulse is provided by the unipolar pulse's rising phase. The second phase is formed during the fall time of the unipolar pulse, when the inductor, which was previously charged during the flat part of the unipolar pulse, discharges its current to the load. The fourth type of generator uses multiple MOSFET switches stacked to turn on a pre-charged, bipolar RC network. This approach is the most flexible in that it can generate multiphasic pulses that have different amplitudes, delays, and durations. However, it may not be suitable for producing short nanosecond pulses (<100 ns), whereas the PFL approach and the RLC approach with gas switches are used for this range. Thus, each generator has its own advantages and applicable range. Copyright © 2018 Elsevier B.V. All rights reserved.

Nonlinear unitary transformations of space-variant polarized light fields from self-induced geometric-phase optical elements

NASA Astrophysics Data System (ADS)

Kravets, Nina; Brasselet, Etienne

2018-01-01

We propose to couple the optical orientational nonlinearities of liquid crystals with their ability to self-organize to tailor them to control space-variant-polarized optical fields in a nonlinear manner. Experimental demonstration is made using a liquid crystal light valve that behaves like a light-driven geometric phase optical element. We also unveil two original nonlinear optical processes, namely self-induced separability and nonseparability. These results contribute to the advancement of nonlinear singular optics that is still in its infancy despite 25 years of effort, which may foster the development of nonlinear protocols to manipulate high-dimensional optical information both in the classical and quantum regimes.

Interferometric sensitivity and entanglement by scanning through quantum phase transitions in spinor Bose-Einstein condensates

NASA Astrophysics Data System (ADS)

Feldmann, P.; Gessner, M.; Gabbrielli, M.; Klempt, C.; Santos, L.; Pezzè, L.; Smerzi, A.

2018-03-01

Recent experiments demonstrated the generation of entanglement by quasiadiabatically driving through quantum phase transitions of a ferromagnetic spin-1 Bose-Einstein condensate in the presence of a tunable quadratic Zeeman shift. We analyze, in terms of the Fisher information, the interferometric value of the entanglement accessible by this approach. In addition to the Twin-Fock phase studied experimentally, we unveil a second regime, in the broken axisymmetry phase, which provides Heisenberg scaling of the quantum Fisher information and can be reached on shorter time scales. We identify optimal unitary transformations and an experimentally feasible optimal measurement prescription that maximize the interferometric sensitivity. We further ascertain that the Fisher information is robust with respect to nonadiabaticity and measurement noise. Finally, we show that the quasiadiabatic entanglement preparation schemes admit higher sensitivities than dynamical methods based on fast quenches.

Topological Classification of Crystalline Insulators through Band Structure Combinatorics

NASA Astrophysics Data System (ADS)

Kruthoff, Jorrit; de Boer, Jan; van Wezel, Jasper; Kane, Charles L.; Slager, Robert-Jan

2017-10-01

We present a method for efficiently enumerating all allowed, topologically distinct, electronic band structures within a given crystal structure in all physically relevant dimensions. The algorithm applies to crystals without time-reversal, particle-hole, chiral, or any other anticommuting or anti-unitary symmetries. The results presented match the mathematical structure underlying the topological classification of these crystals in terms of K -theory and therefore elucidate this abstract mathematical framework from a simple combinatorial perspective. Using a straightforward counting procedure, we classify all allowed topological phases of spinless particles in crystals in class A . Employing this classification, we study transitions between topological phases within class A that are driven by band inversions at high-symmetry points in the first Brillouin zone. This enables us to list all possible types of phase transitions within a given crystal structure and to identify whether or not they give rise to intermediate Weyl semimetallic phases.

Number-phase minimum-uncertainty state with reduced number uncertainty in a Kerr nonlinear interferometer

NASA Astrophysics Data System (ADS)

Kitagawa, M.; Yamamoto, Y.

1987-11-01

An alternative scheme for generating amplitude-squeezed states of photons based on unitary evolution which can properly be described by quantum mechanics is presented. This scheme is a nonlinear Mach-Zehnder interferometer containing an optical Kerr medium. The quasi-probability density (QPD) and photon-number distribution of the output field are calculated, and it is demonstrated that the reduced photon-number uncertainty and enhanced phase uncertainty maintain the minimum-uncertainty product. A self-phase-modulation of the single-mode quantized field in the Kerr medium is described based on localized operators. The spatial evolution of the state is demonstrated by QPD in the Schroedinger picture. It is shown that photon-number variance can be reduced to a level far below the limit for an ordinary squeezed state, and that the state prepared using this scheme remains a number-phase minimum-uncertainty state until the maximum reduction of number fluctuations is surpassed.

Alternative working fluids for unitary equipment: A research perspective

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

Baxter, V.D.

This paper deals with present and planned ORNL activities to characterize alternatives to R-22 for unitary heat pump and air-conditioning applications. Results of small-scale bread-board tests of potential alternatives R-32, R-134a, R-152a and R-143a are discussed. Portions of the AFEAS/DOE global warming impact study dealing with the unitary application are summarized. Methods for leak detection with the new refrigerants are discussed.

Unidirectional Quantum Remote Control: Teleportation of Control-State

NASA Astrophysics Data System (ADS)

Zheng, Yi-Zhuang; Gu, Yong-Jian; Wu, Gui-Chu; Guo, Guang-Can

2003-08-01

We investigate the problem of teleportation of unitary operations by unidirectional control-state teleportation and propose a scheme called unidirectional quantum remote control. The scheme is based on the isomorphism between operation and state. It allows us to store a unitary operation in a control state, thereby teleportation of the unitary operation can be implemented by unidirectional teleportation of the control-state. We find that the probability of success for implementing an arbitrary unitary operation on arbitrary M-qubit state by unidirectional control-state teleportation is 4-M, and 2M ebits and 4M cbits are consumed in each teleportation. The project supported by the National Fundamental Research Programme (2001CB309300) and the Zhejiang Provincial Natural Science Foundation of China under Grant No. 102068

From few-cycle femtosecond pulse to single attosecond pulse-controlling and tracking electron dynamics with attosecond precision

NASA Astrophysics Data System (ADS)

Wang, He

The few-cycle femtosecond laser pulse has proved itself to be a powerful tool for controlling the electron dynamics inside atoms and molecules. By applying such few-cycle pulses as a driving field, single isolated attosecond pulses can be produced through the high-order harmonic generation process, which provide a novel tool for capturing the real time electron motion. The first part of the thesis is devoted to the state of the art few-cycle near infrared (NIR) laser pulse development, which includes absolute phase control (carrier-envelope phase stabilization), amplitude control (power stabilization), and relative phase control (pulse compression and shaping). Then the double optical gating (DOG) method for generating single attosecond pulses and the attosecond streaking experiment for characterizing such pulses are presented. Various experimental limitations in the attosecond streaking measurement are illustrated through simulation. Finally by using the single attosecond pulses generated by DOG, an attosecond transient absorption experiment is performed to study the autoionization process of argon. When the delay between a few-cycle NIR pulse and a single attosecond XUV pulse is scanned, the Fano resonance shapes of the argon autoionizing states are modified by the NIR pulse, which shows the direct observation and control of electron-electron correlation in the temporal domain.

Merging and energy exchange between optical filaments

NASA Astrophysics Data System (ADS)

Georgieva, D. A.; Kovachev, L. M.

2015-10-01

We investigate nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing Pcr trough the processes of cross-phase modulation (CPM) and degenerate four-photon parametric mixing (FPPM). When there is no initial phase difference between the pulses we observe attraction between pulses due to CPM. The final result is merging between the pulses in a single filament with higher power. By method of moments it is found that the attraction depends on the distance between the pulses and has potential character. In the second case we study energy exchange between filaments. This process is described through FPPM scheme and requests initial phase difference between the waves.

Merging and energy exchange between optical filaments

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

Georgieva, D. A., E-mail: dgeorgieva@tu-sofia.bg; Kovachev, L. M.

2015-10-28

We investigate nonlinear interaction between collinear femtosecond laser pulses with power slightly above the critical for self-focusing P{sub cr} trough the processes of cross-phase modulation (CPM) and degenerate four-photon parametric mixing (FPPM). When there is no initial phase difference between the pulses we observe attraction between pulses due to CPM. The final result is merging between the pulses in a single filament with higher power. By method of moments it is found that the attraction depends on the distance between the pulses and has potential character. In the second case we study energy exchange between filaments. This process is describedmore » through FPPM scheme and requests initial phase difference between the waves.« less

Single-shot detection and direct control of carrier phase drift of midinfrared pulses.

PubMed

Manzoni, Cristian; Först, Michael; Ehrke, Henri; Cavalleri, Andrea

2010-03-01

We introduce a scheme for single-shot detection and correction of the carrier-envelope phase (CEP) drift of femtosecond pulses at mid-IR wavelengths. Difference frequency mixing between the mid-IR field and a near-IR gate pulse generates a near-IR frequency-shifted pulse, which is then spectrally interfered with a replica of the gate pulse. The spectral interference pattern contains shot-to-shot information of the CEP of the mid-IR field, and it can be used for simultaneous correction of its slow drifts. We apply this technique to detect and compensate long-term phase drifts at 17 microm wavelength, reducing fluctuations to only 110 mrad over hours of operation.

Carrier-Envelope Phase Effect on Atomic Excitation by Few-Cycle rf Pulses

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

Li Hebin; Welch, George R.; Sautenkov, Vladimir A.

2010-03-12

We present an experimental and theoretical study of the carrier-envelope phase effects on population transfer between two bound atomic states interacting with intense ultrashort pulses. Radio frequency pulses are used to transfer population among the ground state hyperfine levels in rubidium atoms. These pulses are only a few cycles in duration and have Rabi frequencies of the order of the carrier frequency. The phase difference between the carrier and the envelope of the pulses has a significant effect on the excitation of atomic coherence and population transfer. We provide a theoretical description of this phenomenon using density matrix equations. Wemore » discuss the implications and possible applications of our results.« less

Phase-stable, multi-µJ femtosecond pulses from a repetition-rate tunable Ti:Sa-oscillator-seeded Yb-fiber amplifier

NASA Astrophysics Data System (ADS)

Saule, T.; Holzberger, S.; De Vries, O.; Plötner, M.; Limpert, J.; Tünnermann, A.; Pupeza, I.

2017-01-01

We present a high-power, MHz-repetition-rate, phase-stable femtosecond laser system based on a phase-stabilized Ti:Sa oscillator and a multi-stage Yb-fiber chirped-pulse power amplifier. A 10-nm band around 1030 nm is split from the 7-fs oscillator output and serves as the seed for subsequent amplification by 54 dB to 80 W of average power. The µJ-level output is spectrally broadened in a solid-core fiber and compressed to 30 fs with chirped mirrors. A pulse picker prior to power amplification allows for decreasing the repetition rate from 74 MHz by a factor of up to 4 without affecting the pulse parameters. To compensate for phase jitter added by the amplifier to the feed-forward phase-stabilized seeding pulses, a self-referencing feed-back loop is implemented at the system output. An integrated out-of-loop phase noise of less than 100 mrad was measured in the band from 0.4 Hz to 400 kHz, which to the best of our knowledge corresponds to the highest phase stability ever demonstrated for high-power, multi-MHz-repetition-rate ultrafast lasers. This system will enable experiments in attosecond physics at unprecedented repetition rates, it offers ideal prerequisites for the generation and field-resolved electro-optical sampling of high-power, broadband infrared pulses, and it is suitable for phase-stable white light generation.

Optical UWB pulse generator using an N tap microwave photonic filter and phase inversion adaptable to different pulse modulation formats.

PubMed

Bolea, Mario; Mora, José; Ortega, Beatriz; Capmany, José

2009-03-30

We propose theoretically and demonstrate experimentally an optical architecture for flexible Ultra-Wideband pulse generation. It is based on an N-tap reconfigurable microwave photonic filter fed by a laser array by using phase inversion in a Mach-Zehnder modulator. Since a large number of positive and negative coefficients can be easily implemented, UWB pulses fitted to the FCC mask requirements can be generated. As an example, a four tap pulse generator is experimentally demonstrated which complies with the FCC regulation. The proposed pulse generator allows different pulse modulation formats since the amplitude, polarity and time delay of generated pulse is controlled.

Non-unitary probabilistic quantum computing

NASA Technical Reports Server (NTRS)

Gingrich, Robert M.; Williams, Colin P.

2004-01-01

We present a method for designing quantum circuits that perform non-unitary quantum computations on n-qubit states probabilistically, and give analytic expressions for the success probability and fidelity.

Nanoparticle formation after nanosecond-laser irradiation of thin gold films

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

Ratautas, Karolis; Gedvilas, Mindaugas; Raciukaitis, Gediminas

2012-07-01

Evolution in nanoparticle formation was observed after nanosecond-laser irradiation of thin gold films on a silicon substrate and physical phenomena leading to the formation of nanoparticles were studied. Gold films of different thickness (3, 5, 10, 15, 20, and 25 nm) were evaporated on the silicon (110) substrate and irradiated with the pulsed nanosecond laser using different pulse energies and the number of pulses in a burst. Experimentally morphological changes appeared in the films only when the pulse energy was high enough to initiate the phase transition. The threshold energy density for phase transitions in the films was estimated frommore » the thermal model of the laser beam and sample interaction. With the pulse energy just above the threshold, it was possible to observe evolution of nanoparticle formation from a plane metal film by changing the number of pulses applied, as duration of the pulse burst represented the time how long the liquid phase existed. The final size of nanoparticles was a function of the film thickness and was found to be independent of the pulse energy and the number of pulses.« less

Slaves immersed in a liberal ideology.

PubMed

Daly, Leslie Kim

2012-01-01

Paradigm debates have been featured in the nursing literature for over four decades. There are at least two opposing paradigms specific to nursing that have remained central in these debates. Advocates of the unitary perspective (or simultaneity paradigm) consider their theories to be more philosophically advanced and contemporary alternatives when compared to the older more traditional ideas characteristic of models they describe as originating from the totality paradigm. In the context of these debates, I focus on some theoretical positions embedded in the unitary perspective, noting their limitations with respect to integrating the individual and social mandates of nursing; nurses are responsible not only for individual health-related needs, but also for the health of the collective. I explore two hypotheses that may explain the powers of endurance of the unitary perspective. Paley, who outlines the origins of nurses' 'slave morality', inspires the first hypothesis. The second hypothesis speaks to the location of nursing knowledge development in the context of liberal ideology. In this work, I outline key conceptualizations of the unitary perspective in order to clearly illustrate the limitations of the unitary perspective for nurses' social mandate. Then, I explore how slave morality and liberal ideological assumptions might both work to sustain the unitary perspective. A paradigm for nursing must have utility in addressing both the health-related needs of individuals, and for addressing the health of the collective. To this end, I advance suggestions in three areas: first, to transform nurses' slave morality to more honest and noble aspirations; second, to examine liberal ideological premises; and third, to end paradigm debate by resituating elements of the unitary perspective to the level of mid-range theory, where it could be most effective for research and practice with specific populations. © 2011 Blackwell Publishing Ltd.

Caring science and the science of unitary human beings: a trans-theoretical discourse for nursing knowledge development.

PubMed

Watson, Jean; Smith, Marlaine C

2002-03-01

Two dominant discourses in contemporary nursing theory and knowledge development have evolved over the past few decades, in part by unitary science views and caring theories. Rogers' science of unitary human beings (SUHB) represents the unitary directions in nursing. Caring theories and related caring science (CS) scholarship represent the other. These two contemporary initiatives have generated two parallel, often controversial, seemingly separate and unrelated, trees of knowledge for nursing science. This paper explores the evolution of CS and its intersection with SUHB that have emerged in contemporary nursing literature. We present a case for integration, convergence, and creative synthesis of CS with SUHB. A trans-theoretical, trans-disciplinary context emerges, allowing nursing to sustain its caring ethic and ontology, within a unitary science. The authors critique and review the seminal, critical issues that have separated contemporary knowledge developments in CS and SUHB. Foundational issues of CS, and Watson's theory of transpersonal caring science (TCS), as a specific exemplar, are analysed, alongside parallel themes in SUHB. By examining hidden ethical-ontological and paradigmatic commonalities, trans-theoretical themes and connections are explored and revealed between TCS and SUHB. Through a creative synthesis of TCS and SUHB we explicate a distinct unitary view of human with a relational caring ontology and ethic that informs nursing as well as other sciences. The result: is a trans-theoretical, trans-disciplinary view for nursing knowledge development. Nursing's history has been to examine theoretical differences rather than commonalities. This trans-theoretical position moves nursing toward theoretical integration and creative synthesis, vs. separation, away from the 'Balkanization' of different theories. This initiative still maintains the integrity of different theories, while facilitating and inviting a new discourse for nursing science. The result: Unitary Caring Science that evokes both science and spirit.

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

ERIC Educational Resources Information Center

Duoos, Bridget A.

2012-01-01

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

Artists in Schools: "Kick Starting" or "Kicking Out" Dance from New Zealand Classrooms

ERIC Educational Resources Information Center

Snook, Barbara; Buck, Ralph

2014-01-01

New Zealand primary school teachers have access to a comprehensive arts curriculum that includes dance, drama, music, and visual arts. This research focused on several teachers' reality of implementing the dance curriculum in New Zealand primary schools, drawing on Snook's (2012) study in this field. Our research valued the voices of teachers,…

The Role of Postural Support in Young Adults' Control of Stationary Kicking

ERIC Educational Resources Information Center

Sidaway, Ben; Bouchard, Matthew; Chasse, Julie; Dunn, Jonathan; Govoni, Andrea; McPherson, Breanne; Roy, Katherine; Anderson, David I.

2017-01-01

Purpose: The requirement for postural stability during the performance of motor skills has been clearly demonstrated in infants, but the necessity for such a postural substrate is not well documented in adults. The present study investigated the role of postural stability during a ballistic ball-kicking task in adults by providing varying degrees…

Promoting Healthy Lifestyle Behaviour through the Life-Orientation Curriculum: Teachers' Perceptions of the HealthKick Intervention

ERIC Educational Resources Information Center

Hill, Jillian; Draper, Catherine E.; De Villiers, Anniza; Fourie, Jean M.; Mohamed, Suraya; Parker, Whadi-ah; Steyn, Nelia

2015-01-01

This study explores the feasibility of implementing the curriculum and action-planning components of the HealthKick (HK) intervention in eight low-resourced schools in the Western Cape, South Africa. Process evaluation comprising workshops and personal interactions with teachers and principals were followed up with semi-structured interviews and…

Momentum-kick model description of the ridge in {Delta}{phi}-{Delta}{eta} correlations in pp collisions at 7 TeV

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

Wong, Cheuk-Yin

2011-08-15

The near-side ridge structure in the {Delta}{phi}-{Delta}{eta} correlation observed by the CMS Collaboration for pp collisions at 7 TeV at the Large Hadron Collider can be explained by the momentum kick model in which the ridge particles are medium partons that suffer a collision with the jet and acquire a momentum kick along the jet direction. Similar to the early medium parton momentum distribution obtained in previous analysis for nucleus-nucleus collisions at {radical}(s{sub NN})=0.2 TeV, the early medium parton momentum distribution in pp collisions at 7 TeV exhibits a rapidity plateau as arising from particle production in a flux tube.

Propulsive efficiency of the underwater dolphin kick in humans.

PubMed

von Loebbecke, Alfred; Mittal, Rajat; Fish, Frank; Mark, Russell

2009-05-01

Three-dimensional fully unsteady computational fluid dynamic simulations of five Olympic-level swimmers performing the underwater dolphin kick are used to estimate the swimmer's propulsive efficiencies. These estimates are compared with those of a cetacean performing the dolphin kick. The geometries of the swimmers and the cetacean are based on laser and CT scans, respectively, and the stroke kinematics is based on underwater video footage. The simulations indicate that the propulsive efficiency for human swimmers varies over a relatively wide range from about 11% to 29%. The efficiency of the cetacean is found to be about 56%, which is significantly higher than the human swimmers. The computed efficiency is found not to correlate with either the slender body theory or with the Strouhal number.

KSC-2012-5016

NASA Image and Video Library

2012-09-06

CAPE CANAVERAL, Fla. – During NASA's Innovation Expo at the Kennedy Space Center in Florida, Annie Williams, of NASA's Medical and Environmental Management Division, proposes an innovation to recycling space hardware as art. Kennedy Kick-Start Chair Mike Conroy looks on from the left. As Kennedy continues developing programs and infrastructure to become a 21st century spaceport, many employees are devising ways to do their jobs better and more efficiently. On Sept. 6, 2012, 16 Kennedy employees pitched their innovative ideas for improving the center at the Kennedy Kick-Start event. The competition was part of a center-wide effort designed to increase exposure for innovative ideas and encourage their implementation. For more information, visit http://www.nasa.gov/centers/kennedy/news/kick-start_competition.html Photo credit: NASA/Gianni Woods

A Dihydropyridine-sensitive Voltage-dependent Calcium Channel in the Sarcolemmal Membrane of Crustacean Muscle

PubMed Central

Erxleben, Christian; Rathmayer, Werner

1997-01-01

Single-channel currents through calcium channels in muscle of a marine crustacean, the isopod Idotea baltica, were investigated in cell-attached patches. Inward barium currents were strongly voltage-dependent, and the channels were closed at the cell's resting membrane potential. The open probability (Po) increased e-fold for an 8.2 mV (±2.4, n = 13) depolarization. Channel openings were mainly brief (<0.3 ms) and evenly distributed throughout 100-ms pulses. Averaged, quasimacroscopic currents showed fast activation and deactivation and did not inactivate during 100-ms test pulses. Similarly, channel activity persisted at steadily depolarized holding potentials. With 200 mM Ba2+ as charge carrier, the average slope conductance from the unitary currents between +30 and +80 mV, was 20 pS (±2.6, n = 12). The proportion of long openings, which were very infrequent under control conditions, was greatly increased by preincubation of the muscle fibers with the calcium channel agonist, the dihydropyridine Bay K8644 (10–100 μM). Properties of these currents resemble those through the L-type calcium channels of mammalian nerve, smooth muscle, and cardiac muscle cells. PMID:9089439

Unconditional polarization qubit quantum memory at room temperature

NASA Astrophysics Data System (ADS)

Namazi, Mehdi; Kupchak, Connor; Jordaan, Bertus; Shahrokhshahi, Reihaneh; Figueroa, Eden

2016-05-01

The creation of global quantum key distribution and quantum communication networks requires multiple operational quantum memories. Achieving a considerable reduction in experimental and cost overhead in these implementations is thus a major challenge. Here we present a polarization qubit quantum memory fully-operational at 330K, an unheard frontier in the development of useful qubit quantum technology. This result is achieved through extensive study of how optical response of cold atomic medium is transformed by the motion of atoms at room temperature leading to an optimal characterization of room temperature quantum light-matter interfaces. Our quantum memory shows an average fidelity of 86.6 +/- 0.6% for optical pulses containing on average 1 photon per pulse, thereby defeating any classical strategy exploiting the non-unitary character of the memory efficiency. Our system significantly decreases the technological overhead required to achieve quantum memory operation and will serve as a building block for scalable and technologically simpler many-memory quantum machines. The work was supported by the US-Navy Office of Naval Research, Grant Number N00141410801 and the Simons Foundation, Grant Number SBF241180. B. J. acknowledges financial assistance of the National Research Foundation (NRF) of South Africa.

Cardiac cell: a biological laser?

PubMed

Chorvat, D; Chorvatova, A

2008-04-01

We present a new concept of cardiac cells based on an analogy with lasers, practical implementations of quantum resonators. In this concept, each cardiac cell comprises a network of independent nodes, characterised by a set of discrete energy levels and certain transition probabilities between them. Interaction between the nodes is given by threshold-limited energy transfer, leading to quantum-like behaviour of the whole network. We propose that in cardiomyocytes, during each excitation-contraction coupling cycle, stochastic calcium release and the unitary properties of ionic channels constitute an analogue to laser active medium prone to "population inversion" and "spontaneous emission" phenomena. This medium, when powered by an incoming threshold-reaching voltage discharge in the form of an action potential, responds to the calcium influx through L-type calcium channels by stimulated emission of Ca2+ ions in a coherent, synchronised and amplified release process known as calcium-induced calcium release. In parallel, phosphorylation-stimulated molecular amplification in protein cascades adds tuneable features to the cells. In this framework, the heart can be viewed as a coherent network of synchronously firing cardiomyocytes behaving as pulsed laser-like amplifiers, coupled to pulse-generating pacemaker master-oscillators. The concept brings a new viewpoint on cardiac diseases as possible alterations of "cell lasing" properties.

Phase incremented echo train acquisition applied to magnetic resonance pore imaging

NASA Astrophysics Data System (ADS)

Hertel, S. A.; Galvosas, P.

2017-02-01

Efficient phase cycling schemes remain a challenge for NMR techniques if the pulse sequences involve a large number of rf-pulses. Especially complex is the Carr Purcell Meiboom Gill (CPMG) pulse sequence where the number of rf-pulses can range from hundreds to several thousands. Our recent implementation of Magnetic Resonance Pore Imaging (MRPI) is based on a CPMG rf-pulse sequence in order to refocus the effect of internal gradients inherent in porous media. While the spin dynamics for spin- 1 / 2 systems in CPMG like experiments are well understood it is still not straight forward to separate the desired pathway from the spectrum of unwanted coherence pathways. In this contribution we apply Phase Incremented Echo Train Acquisition (PIETA) to MRPI. We show how PIETA offers a convenient way to implement a working phase cycling scheme and how it allows one to gain deeper insights into the amplitudes of undesired pathways.

Structural and phase transformations in zinc and brass wires under heating with high-density current pulse

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

Pervikov, A. V.

The work is focused on revealing the mechanism of structure and phase transformations in the metal wires under heating with a high-density current pulse (the electric explosion of wires, EEWs). It has been demonstrated on the example of brass and zinc wires that the transition of a current pulse with the density of j ≈ 3.3 × 10{sup 7} A/cm{sup 2} results in homogeneous heating of the crystalline structure of the metal/alloy. It has been determined that under heating with a pulse of high-density current pulse, the electric resistance of the liquid phases of zinc and brass decreases as the temperature increases. The results obtainedmore » allow for a conclusion that the presence of the particles of the condensed phase in the expanding products of EEW is the result of overheating instabilities in the liquid metal.« less

Pulse Oximeter Derived Blood Pressure Measurement in Patients With a Continuous Flow Left Ventricular Assist Device.

PubMed

Hellman, Yaron; Malik, Adnan S; Lane, Kathleen A; Shen, Changyu; Wang, I-Wen; Wozniak, Thomas C; Hashmi, Zubair A; Munson, Sarah D; Pickrell, Jeanette; Caccamo, Marco A; Gradus-Pizlo, Irmina; Hadi, Azam

2017-05-01

Currently, blood pressure (BP) measurement is obtained noninvasively in patients with continuous flow left ventricular assist device (LVAD) by placing a Doppler probe over the brachial or radial artery with inflation and deflation of a manual BP cuff. We hypothesized that replacing the Doppler probe with a finger-based pulse oximeter can yield BP measurements similar to the Doppler derived mean arterial pressure (MAP). We conducted a prospective study consisting of patients with contemporary continuous flow LVADs. In a small pilot phase I inpatient study, we compared direct arterial line measurements with an automated blood pressure (ABP) cuff, Doppler and pulse oximeter derived MAP. Our main phase II study included LVAD outpatients with a comparison between Doppler, ABP, and pulse oximeter derived MAP. A total of five phase I and 36 phase II patients were recruited during February-June 2014. In phase I, the average MAP measured by pulse oximeter was closer to arterial line MAP rather than Doppler (P = 0.06) or ABP (P < 0.01). In phase II, pulse oximeter MAP (96.6 mm Hg) was significantly closer to Doppler MAP (96.5 mm Hg) when compared to ABP (82.1 mm Hg) (P = 0.0001). Pulse oximeter derived blood pressure measurement may be as reliable as Doppler in patients with continuous flow LVADs. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

Techniques for the characterization of sub-10-fs optical pulses: a comparison

NASA Astrophysics Data System (ADS)

Gallmann, L.; Sutter, D. H.; Matuschek, N.; Steinmeyer, G.; Keller, U.

Several methods have been proposed for the phase and amplitude characterization of sub-10-fs pulses with nJ energies. An overview of these techniques is presented, with a focus on the comparison of second-harmonic generation frequency-resolved optical gating (SHG-FROG) and spectral phase interferometry for direct electric-field reconstruction (SPIDER). We describe a collinear FROG variant based on type-II phase-matching that completely avoids the geometrical blurring artifact and use both this and SPIDER for the characterization of sub-10-fs Ti:sapphire laser pulses. The results of both methods are compared in an extensive statistical analysis. From this first direct experimental comparison of FROG and SPIDER, guidelines for accurate measurements of sub-10-fs pulses are derived. We point out limitations of both methods for pulses in this ultrashort pulse regime.

A Secondary Ion Mass Analyzer for Remote Surface Composition Analysis of the Galilean Moons

NASA Technical Reports Server (NTRS)

Krueger, H.; Srama, R.; Johnson, T. V.; Henkel, H.; vonHoerner, H.; Koch, A.; Horanyi, M.; Gruen, E.; Kissel, J.; Krueger, F.

2003-01-01

Galileo in-situ dust measurements have shown that the Galilean moons are surrounded by tenuous dust clouds formed by collisional ejecta from their icy surfaces, kicked up by impacts of interplanetary micrometeoroids. The majority of the ejecta dust particles have been sensed at altitudes below five between 0.5 and 1 micron, just above the detector threshold, indicating a size distribution decreasing towards bigger particles. their parent bodies. They carry information about the properties of the surface from which they have been kicked up. In particular, these grains may carry organic compounds and other chemicals of biological relevance if they exist on the icy Galilean moons. In-situ analysis of the grain composition with a sophisticated dust analyzer instrument flying on a Jupiter Icy Moons Orbiter can provide important information about geochemical and geophysical processes during the evolutionary histories of these moons which are not accessible with other techniques from an orbiter spacecraft. Thus, spacecraft-based in-situ dust measurements can be used as a diagnostic tool for the analysis of the surface composition of the moons. This way, the in-situ measurements turn into a remote sensing technique by using the dust instrument like a telescope for surface investigation. An instrument capable of very high resolution composition analysis of dust particles is the Cometary Secondary Ion Mass Analyzer (COSIMA). The instrument was originally developed for the Comet Rendezvous and Asteroid Flyby (CRAF) mission and has now been built for ESA'S comet orbiter Rosetta. Dust particles are collected on a target and are later located by an optical microscope camera. A pulsed primary indium ion gun partially ionizes the dust grains. The generated secondary ions are accelerated in an electric field and travel through a reflectron-type time-of-flight ion mass spectrometer.

Wakefields in SLAC linac collimators

DOE PAGES

Novokhatski, A.; Decker, F. -J.; Smith, H.; ...

2014-12-02

When a beam travels near collimator jaws, it gets an energy loss and a transverse kick due to the backreaction of the beam field diffracted from the jaws. The effect becomes very important for an intense short bunch when a tight collimation of the background beam halo is required. In the Linac Coherent Light Source at SLAC a collimation system is used to protect the undulators from radiation due to particles in the beam halo. The halo is most likely formed from gun dark current or dark current in some of the accelerating sections. However, collimators are also responsible formore » the generation of wake fields. The wake field effect from the collimators not only brings an additional energy jitter and change in the trajectory of the beam, but it also rotates the beam on the phase plane, which consequently leads to a degradation of the performance of the Free Electron Laser at the Linac Coherent Light Source. In this paper, we describe a model of the wake field radiation in the SLAC linac collimators. We use the results of a numerical simulation to illustrate the model. Based on the model, we derive simple formulas for the bunch energy loss and the average kick. We also present results from experimental measurements that confirm our model.« less

Black Hole Formation and Fallback during the Supernova Explosion of a 40 M ⊙ Star

NASA Astrophysics Data System (ADS)

Chan, Conrad; Müller, Bernhard; Heger, Alexander; Pakmor, Rüdiger; Springel, Volker

2018-01-01

Fallback in core-collapse supernovae is considered a major ingredient for explaining abundance anomalies in metal-poor stars and the natal kicks and spins of black holes (BHs). We present a first 3D simulation of BH formation and fallback in an “aborted” neutrino-driven explosion of a 40 solar mass zero-metallicity progenitor from collapse to shock breakout. We follow the phase up to BH formation using the relativistic COCONUT-FMT code. For the subsequent evolution to shock breakout we apply the moving-mesh code AREPO to core-collapse supernovae for the first time. Our simulation shows that despite early BH formation, neutrino-heated bubbles can survive for tens of seconds before being accreted, leaving them sufficient time to transfer part of their energy to sustain the shock wave as is propagates through the envelope. Although the initial net energy (∼2 Bethe) of the neutrino-heated ejecta barely equals the binding energy of the envelope, 11 {M}ȯ of hydrogen are still expelled with an energy of 0.23 Bethe. We find no significant mixing and only a modest BH kick and spin, but speculate that stronger effects could occur for slightly more energetic explosions or progenitors with less tightly bound envelopes.

Repetitive Transcranial Magnetic Stimulator with Controllable Pulse Parameters

PubMed Central

Peterchev, Angel V; Murphy, David L; Lisanby, Sarah H

2013-01-01

The characteristics of transcranial magnetic stimulation (TMS) pulses influence the physiological effect of TMS. However, available TMS devices allow very limited adjustment of the pulse parameters. We describe a novel TMS device that uses a circuit topology incorporating two energy storage capacitors and two insulated-gate bipolar transistor (IGBT) modules to generate near-rectangular electric field pulses with adjustable number, polarity, duration, and amplitude of the pulse phases. This controllable pulse parameter TMS (cTMS) device can induce electric field pulses with phase widths of 10–310 μs and positive/negative phase amplitude ratio of 1–56. Compared to conventional monophasic and biphasic TMS, cTMS reduces energy dissipation by up to 82% and 57%, and decreases coil heating by up to 33% and 41%, respectively. We demonstrate repetitive TMS trains of 3,000 pulses at frequencies up to 50 Hz with electric field pulse amplitude and width variability less than the measurement resolution (1.7% and 1%, respectively). Offering flexible pulse parameter adjustment and reduced power consumption and coil heating, cTMS enhances existing TMS paradigms, enables novel research applications, and could lead to clinical applications with potentially enhanced potency. PMID:21540487

The pulse-pair algorithm as a robust estimator of turbulent weather spectral parameters using airborne pulse Doppler radar

NASA Technical Reports Server (NTRS)

Baxa, Ernest G., Jr.; Lee, Jonggil

1991-01-01

The pulse pair method for spectrum parameter estimation is commonly used in pulse Doppler weather radar signal processing since it is economical to implement and can be shown to be a maximum likelihood estimator. With the use of airborne weather radar for windshear detection, the turbulent weather and strong ground clutter return spectrum differs from that assumed in its derivation, so the performance robustness of the pulse pair technique must be understood. Here, the effect of radar system pulse to pulse phase jitter and signal spectrum skew on the pulse pair algorithm performance is discussed. Phase jitter effect may be significant when the weather return signal to clutter ratio is very low and clutter rejection filtering is attempted. The analysis can be used to develop design specifications for airborne radar system phase stability. It is also shown that the weather return spectrum skew can cause a significant bias in the pulse pair mean windspeed estimates, and that the poly pulse pair algorithm can reduce this bias. It is suggested that use of a spectrum mode estimator may be more appropriate in characterizing the windspeed within a radar range resolution cell for detection of hazardous windspeed gradients.

Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors.

DTIC Science & Technology

1999-01-01

AFRL-ML-TY-TP-1999-4546 RETICULATED VITREOUS CARBON ELECTRODES FOR GAS PHASE PULSED CORONA REACTORS B.R. LOCKE M. KIRKPATRICK H. HANSON W.C...SUBTITLE Reticulated Vitreous Carbon Electrodes for Gas Phase Pulsed Corona Reactors 6. AUTHOR(S) B.R. Locke, M. Kirkpatrick, H. Hanson, and W.C. Finney...incorporating reticulated vitreous carbon electrodes is demonstrated to be effective for the removal of nitrogen oxides from synthetic air mixtures

Design and calibration of zero-additional-phase SPIDER

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

Baum, Peter; Riedle, Eberhard

2005-09-01

Zero-additional-phase spectral phase interferometry for direct electric field reconstruction (ZAP-SPIDER) is a novel technique for measuring the temporal shape and phase of ultrashort optical pulses directly at the interaction point of a spectroscopic experiment. The scheme is suitable for an extremely wide wavelength region from the ultraviolet to the near infrared. We present a comprehensive description of the experimental setup and design guidelines to effectively apply the technique to various wavelengths and pulse durations. The calibration of the setup and procedures to check the consistency of the measurement are discussed in detail. We show experimental data for various center wavelengthsmore » and pulse durations down to 7 fs to verify the applicability to a wide range of pulse parameters.« less

Quasi-phase matching and quantum control of high harmonic generation in waveguides using counterpropagating beams

DOEpatents

Zhang, Xiaoshi; Lytle, Amy L.; Cohen, Oren; Kapteyn, Henry C.; Murnane, Margaret M.

2010-11-09

All-optical quasi-phase matching (QPM) uses a train of counterpropagating pulses to enhance high-order harmonic generation (HHG) in a hollow waveguide. A pump pulse enters one end of the waveguide, and causes HHG in the waveguide. The counterpropagation pulses enter the other end of the waveguide and interact with the pump pulses to cause QPM within the waveguide, enhancing the HHG.

Grism compressor for carrier-envelope phase-stable millijoule-energy chirped pulse amplifier lasers featuring bulk material stretcher.

PubMed

Ricci, A; Jullien, A; Forget, N; Crozatier, V; Tournois, P; Lopez-Martens, R

2012-04-01

We demonstrate compression of amplified carrier-envelope phase (CEP)-stable laser pulses using paired transmission gratings and high-index prisms, or grisms, with chromatic dispersion matching that of a bulk material pulse stretcher. Grisms enable the use of larger bulk stretching factors and thereby higher energy pulses with lower B-integral in a compact amplifier design suitable for long-term CEP control.

Attosecond pulse carrier-envelope phase effects on ionized electron momentum and energy distributions

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

Peng, L.-Y.; Starace, Anthony F.

2007-10-15

We analyze carrier-envelope phase (CEP) effects on electron wave-packet momentum and energy spectra produced by one or two few-cycle attosecond xuv pulses. The few-cycle attosecond pulses are assumed to have arbitrary phases. We predict CEP effects on ionized electron wave-packet momentum distributions produced by attosecond pulses having durations comparable to those obtained by Sansone et al. [Science 314, 443 (2006)]. The onset of significant CEP effects is predicted to occur for attosecond pulse field strengths close to those possible with current experimental capabilities. Our results are based on single-active-electron solutions of the three-dimensional, time-dependent Schroedinger equation including atomic potentials appropriatemore » for the H and He atoms.« less

Detailed Characterization of Local Field Potential Oscillations and Their Relationship to Spike Timing in the Antennal Lobe of the Moth Manduca sexta

PubMed Central

Daly, Kevin C.; Galán, Roberto F.; Peters, Oakland J.; Staudacher, Erich M.

2011-01-01

The transient oscillatory model of odor identity encoding seeks to explain how odorants with spatially overlapped patterns of input into primary olfactory networks can be discriminated. This model provides several testable predictions about the distributed nature of network oscillations and how they control spike timing. To test these predictions, 16 channel electrode arrays were placed within the antennal lobe (AL) of the moth Manduca sexta. Unitary spiking and multi site local field potential (LFP) recordings were made during spontaneous activity and in response to repeated presentations of an odor panel. We quantified oscillatory frequency, cross correlations between LFP recording sites, and spike–LFP phase relationships. We show that odor-driven AL oscillations in Manduca are frequency modulating (FM) from ∼100 to 30 Hz; this was odorant and stimulus duration dependent. FM oscillatory responses were localized to one or two recording sites suggesting a localized (perhaps glomerular) not distributed source. LFP cross correlations further demonstrated that only a small (r < 0.05) distributed and oscillatory component was present. Cross spectral density analysis demonstrated the frequency of these weakly distributed oscillations was state dependent (spontaneous activity = 25–55 Hz; odor-driven = 55–85 Hz). Surprisingly, vector strength analysis indicated that unitary phase locking of spikes to the LFP was strongest during spontaneous activity and dropped significantly during responses. Application of bicuculline, a GABAA receptor antagonist, significantly lowered the frequency content of odor-driven distributed oscillatory activity. Bicuculline significantly reduced spike phase locking generally, but the ubiquitous pattern of increased phase locking during spontaneous activity persisted. Collectively, these results indicate that oscillations perform poorly as a stimulus-mediated spike synchronizing mechanism for Manduca and hence are incongruent with the transient oscillatory model. PMID:22046161

Pulse width modulation inverter with battery charger

DOEpatents

Slicker, James M.

1985-01-01

An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a "flyback" DC-DC converter circuit for recharging the battery.

Pulse width modulation inverter with battery charger

NASA Technical Reports Server (NTRS)

Slicker, James M. (Inventor)

1985-01-01

An inverter is connected between a source of DC power and a three-phase AC induction motor, and a microprocessor-based circuit controls the inverter using pulse width modulation techniques. In the disclosed method of pulse width modulation, both edges of each pulse of a carrier pulse train are equally modulated by a time proportional to sin .theta., where .theta. is the angular displacement of the pulse center at the motor stator frequency from a fixed reference point on the carrier waveform. The carrier waveform frequency is a multiple of the motor stator frequency. The modulated pulse train is then applied to each of the motor phase inputs with respective phase shifts of 120.degree. at the stator frequency. Switching control commands for electronic switches in the inverter are stored in a random access memory (RAM) and the locations of the RAM are successively read out in a cyclic manner, each bit of a given RAM location controlling a respective phase input of the motor. The DC power source preferably comprises rechargeable batteries and all but one of the electronic switches in the inverter can be disabled, the remaining electronic switch being part of a flyback DC-DC converter circuit for recharging the battery.

Non-Markovianity Measure Based on Brukner-Zeilinger Invariant Information for Unital Quantum Dynamical Maps

NASA Astrophysics Data System (ADS)

He, Zhi; Zhu, Lie-Qiang; Li, Li

2017-03-01

A non-Markovianity measure based on Brukner-Zeilinger invariant information to characterize non-Markovian effect of open systems undergoing unital dynamical maps is proposed. The method takes advantage of non-increasing property of the Brukner-Zeilinger invariant information under completely positive and trace-preserving unital maps. The simplicity of computing the Brukner-Zeilinger invariant information is the advantage of the proposed measure because of mainly depending on the purity of quantum state. The measure effectively captures the characteristics of non-Markovianity of unital dynamical maps. As some concrete application, we consider two typical non-Markovian noise channels, i.e., the phase damping channel and the random unitary channel to show the sensitivity of the proposed measure. By investigation, we find that the conditions of detecting the non-Markovianity for the phase damping channel are consistent with the results of existing measures for non-Markovianity, i.e., information flow, divisibility and quantum mutual information. However, for the random unitary channel non-Markovian conditions are same to that of the information flow, but is different from that of the divisibility and quantum mutual information. Supported by the National Natural Science Foundation of China under Grant No. 61505053, the Natural Science Foundation of Hunan Province under Grant No. 2015JJ3092, the Research Foundation of Education Bureau of Hunan Province, China under Grant No. 16B177, the School Foundation from the Hunan University of Arts and Science under Grant No. 14ZD01

Acousto-optic replication of ultrashort laser pulses

NASA Astrophysics Data System (ADS)

Yushkov, Konstantin B.; Molchanov, Vladimir Ya.; Ovchinnikov, Andrey V.; Chefonov, Oleg V.

2017-10-01

Precisely controlled sequences of ultrashort laser pulses are required in various scientific and engineering applications. We developed a phase-only acousto-optic pulse shaping method for replication of ultrashort laser pulses in a TW laser system. A sequence of several Fourier-transform-limited pulses is generated from a single femtosecond laser pulse by means of applying a piecewise linear phase modulation over the whole emission spectrum. Analysis demonstrates that the main factor which limits maximum delay between the pulse replicas is spectral resolution of the acousto-optic dispersive delay line used for pulse shaping. In experiments with a Cr:forsterite laser system, we obtained delays from 0.3 to 3.5 ps between two replicas of 190 fs transform-limited pulses at the central wavelength of laser emission, 1230 nm.

Optimal Synthesis of the Joint Unitary Evolutions

NASA Astrophysics Data System (ADS)

Wei, Hai-Rui; Alsaedi, Ahmed; Hobiny, Aatef; Deng, Fu-Guo; Hu, Hui; Zhang, Dun

2018-07-01

Joint unitary operations play a central role in quantum communication and computation. We give a quantum circuit for implementing a type of unconstructed useful joint unitary evolutions in terms of controlled-NOT (CNOT) gates and single-qubit rotations. Our synthesis is optimal and possible in experiment. Two CNOT gates and seven R x , R y or R z rotations are required for our synthesis, and the arbitrary parameter contained in the evolutions can be controlled by local Hamiltonian or external fields.

Optimal Synthesis of the Joint Unitary Evolutions

NASA Astrophysics Data System (ADS)

Wei, Hai-Rui; Alsaedi, Ahmed; Hobiny, Aatef; Deng, Fu-Guo; Hu, Hui; Zhang, Dun

2018-03-01

Joint unitary operations play a central role in quantum communication and computation. We give a quantum circuit for implementing a type of unconstructed useful joint unitary evolutions in terms of controlled-NOT (CNOT) gates and single-qubit rotations. Our synthesis is optimal and possible in experiment. Two CNOT gates and seven R x , R y or R z rotations are required for our synthesis, and the arbitrary parameter contained in the evolutions can be controlled by local Hamiltonian or external fields.

Bending it like Beckham: how to visually fool the goalkeeper.

PubMed

Dessing, Joost C; Craig, Cathy M

2010-10-06

As bending free-kicks becomes the norm in modern day soccer, implications for goalkeepers have largely been ignored. Although it has been reported that poor sensitivity to visual acceleration makes it harder for expert goalkeepers to perceptually judge where the curved free-kicks will cross the goal line, it is unknown how this affects the goalkeeper's actual movements. Here, an in-depth analysis of goalkeepers' hand movements in immersive, interactive virtual reality shows that they do not fully account for spin-induced lateral ball acceleration. Hand movements were found to be biased in the direction of initial ball heading, and for curved free-kicks this resulted in biases in a direction opposite to those necessary to save the free-kick. These movement errors result in less time to cover a now greater distance to stop the ball entering the goal. These and other details of the interceptive behaviour are explained using a simple mathematical model which shows how the goalkeeper controls his movements online with respect to the ball's current heading direction. Furthermore our results and model suggest how visual landmarks, such as the goalposts in this instance, may constrain the extent of the movement biases. While it has previously been shown that humans can internalize the effects of gravitational acceleration, these results show that it is much more difficult for goalkeepers to account for spin-induced visual acceleration, which varies from situation to situation. The limited sensitivity of the human visual system for detecting acceleration, suggests that curved free-kicks are an important goal-scoring opportunity in the game of soccer.

Supernova kicks and dynamics of compact remnants in the Galactic Centre

NASA Astrophysics Data System (ADS)

Bortolas, Elisa; Mapelli, Michela; Spera, Mario

2017-08-01

The Galactic Centre (GC) is a unique place to study the extreme dynamical processes occurring near a supermassive black hole (SMBH). Here, we investigate the role of supernova (SN) explosions occurring in massive binary systems lying in a disc-like structure within the innermost parsec. We use a regularized algorithm to simulate 3 × 104 isolated three-body systems composed of a stellar binary orbiting the SMBH. We start the integration when the primary member undergoes an SN explosion and analyse the impact of SN kicks on the orbits of stars and compact remnants. We find that SN explosions scatter the lighter stars in the pair on completely different orbits, with higher eccentricity and inclination. In contrast, stellar-mass black holes (BHs) and massive stars retain memory of the orbit of their progenitor star. Our results suggest that SN kicks are not sufficient to eject BHs from the GC. We thus predict that all BHs that form in situ in the central parsec of our Galaxy remain in the GC, building up a cluster of dark remnants. In addition, the change of neutron star (NS) orbits induced by SNe may partially account for the observed dearth of NSs in the GC. About 40 per cent of remnants stay bound to the stellar companion after the kick; we expect up to 70 per cent of them might become X-ray binaries through Roche lobe filling. Finally, the eccentricity of some light stars becomes >0.7 as an effect of the SN kick, producing orbits similar to those of the G1 and G2 dusty objects.

On the impact of neutron star binaries' natal-kick distribution on the Galactic r-process enrichment

NASA Astrophysics Data System (ADS)

Safarzadeh, Mohammadtaher; Côté, Benoit

2017-11-01

We study the impact of the neutron star binaries' (NSBs) natal-kick distribution on the galactic r-process enrichment. We model the growth of a Milky Way type halo based on N-body simulation results and its star formation history based on multi-epoch abundance matching techniques. We consider that the NSBs that merge well beyond the galaxy's effective radius (>2 × Reff) do not contribute to the galactic r-process enrichment. Assuming a power-law delay-time distribution (DTD) function (∝t-1) with tmin = 30 Myr for binaries' coalescence time-scales and an exponential profile for their natal-kick distribution with an average value of 180 km s-1, we show that up to ˜ 40 per cent of all formed NSBs do not contribute to the r-process enrichment by z = 0, either because they merge far from the galaxy at a given redshift (up to ˜ 25 per cent) or have not yet merged by today (˜ 15 per cent). Our result is largely insensitive to the details of the DTD function. Assuming a constant coalescence time-scale of 100 Myr well approximates the adopted DTD although with 30 per cent of the NSBs ending up not contributing to the r-process enrichment. Our results, although rather dependent on the adopted natal-kick distribution, represent the first step towards estimating the impact of natal kicks and DTD functions on the r-process enrichment of galaxies that would need to be incorporated in the hydrodynamical simulations.