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Heart beat may provide clues to kidney health
2010-07-08
Individuals with a high resting heart rate and a low beat-to-beat heart rate variability have an increased risk of developing kidney disease, according to a study appearing in an upcoming issue of the Journal of the ...
2009-01-01
Methamphetamine induces several cardiac dysfunctions, which leads to arrhythmia, cardiac failure and sudden cardiac death. Although these cardiac alterations elicited by methamphetamine were thought to be due to an indirect action of methamphetamine, namely, an excessive catecholamine release from synaptic terminals, while it seems likely that methamphetamine directly modulates the functioning of cardiomyocytes independent of neurotransmitters. However, the direct effects of methamphetamine on cardiomyocytes are still not clear. We show that methamphetamine directly accelerates the beating rate and alters Ca2+ oscillation pattern in cultured neonatal rat cardiomyocytes. Adrenergic receptor antagonists did not block the methamphetamine-induced alterations in cardiomyocytes. Treatment with a...
Double beat-wave mechanism to keep particle in phase with accelerating plasma wave
1985-01-01
Two mechanisms are described by which the phase matching between accelerated particle and accelerating plasma wave in a plasma beat-wave accelerator can be maintained indefinitely. (1) Interference between two beat-waves to cancel (a) the fields in the interfering electromagnetic waves, and (b) electron oscillations which would otherwise be set up by those waves. (2) Alternating plasma density used in conjunction with one or two beat-waves.
Effect of meditation on scaling behavior and complexity of human heart rate variability
2006-12-10
The heart beat data recorded from samples before and during meditation are analyzed using two different scaling analysis methods. These analyses revealed that mediation severely affects the long range correlation of heart beat of a normal heart. Moreover, it is found that meditation induces periodic behavior in the heart beat. The complexity of the heart rate variability is quantified using multiscale entropy analysis and recurrence analysis. The complexity of the heart beat during mediation is found to be more.
Report of the Working Group on Media Accelerators
A summary is given of the activities of those in the Media Accelerator Group. Attention was focused on the Inverse Cherenkov Accelerator, the Laser Focus Accelerator, and the Beat Wave Accelerator. For each of these the ultimate capability of the concept was examined as well as the next series of experiments which needs to be performed in order to advance the concept.
Report of the Working Group on Media Accelerators
1982-04-12
A summary is given of the activities of those in the Media Accelerator Group. Attention was focused on the Inverse Cherenkov Accelerator, the Laser Focus Accelerator, and the Beat Wave Accelerator. For each of these the ultimate capability of the concept was examined as well as the next series of experiments which needs to be performed in order to advance the concept.
Progress on laser plasma accelerators
1986-04-01
Several laser plasma accelerator schemes are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA). Theory indicates that a very high acceleration gradient, of order 1 GeV/m, can exist in the plasma wave driven by the beating lasers. Experimental results obtained on the PBWA experiment at UCLA confirms this. Parameters related to the PBWA as an accelerator system are derived, among them issues concerning the efficiency and the laser power and energy requirements are discussed.
Exploration of phase stability in the surfatron accelerator
Proton and electron motion in a laser beat-wave accelerator with a transverse magnetic field is explored. Parameters of stable acceleration are determined analytically and by simulation. The effects of synchrotron radiation on electron acceleration are also explored.
The prospects for a GeV plasma beat wave accelerator
1994-12-31
In view of the recent progress on the Plasma Beat Wave Accelerator (PBWA), the prospects of accelerating a significant number of electrons to one GeV energy are discussed. The laser, plasma and injector technologies appear to be at hand; furthermore, key issues associated with plasma production, wave excitation, instabilities and acceleration are sufficiently well understood to propose such as undertaking. (author).
Autonomic predictors of recovery following surgery: A comparative study
2010-01-01
Although heart rate and temperature are continuously monitored in patients during recovery following surgery, measures that extract direct manifestations of neural regulation of autonomic circuits from the beat-to-beat heart rate may be more sensitive to outcome. We explore the relationship between features of autonomic regulation and survival in the prairie vole, a small mammal, with features of vagal regulation of the heart similar to humans. Cardiac vagal regulation is manifested in the beat-to-beat heart rate variability (HRV) pattern and can be quantified by extracting measures of the amplitude of periodic oscillations associated with spontaneous breathing. Thus, monitoring beat-to-beat heart rate patterns post-surgery in the prairie vole may provide an opportunity to dynamically asse...
2010-01-01
Monitoring the physiological status and behaviour of free-swimming fishes remains a challenging task, although great promise stems from techniques such as biologging and biotelemetry. Here, implanted data loggers were used to simultaneously measure heart rate (f H), visceral temperature, and a derivation of acceleration in two groups of wild adult sockeye salmon (Oncorhynchus nerka) held at two different water speeds (slow and fast). Calibration experiments performed with individual fish in a swim tunnel respirometer generated strong relationships between acceleration, f H, tail beat frequency and energy expenditure over a wide range of swimming velocities. The regression equations were then used to estimate the overall energy expenditure of the groups of fish held at different water speed...
Continuing studies of the plasma beat wave accelerator
1990-01-01
This is a proposal for the release of third year funds for the Plasma Beat Wave Accelerator'' program (PBWA) at UCLA under the direction of Professor C. Joshi. This report is also a summary of progress on this project since March 1990; i.e., the date of the last report to the DOE. Once again we note that although the program is for historical reasons called the Plasma Beat Wave Accelerator Program, our group is active in all areas of applications of lasers and plasmas in future high energy accelerators. These are as follows: heat gradient plasma structures; excited by plasma beat wave technique; laser wake field technique; and plasma wake field technique. Development of a photoinjector-driven, 20 MeV linac; and theoretical studies of the plasma lens and use of plasmas at the final focus.
2010-01-01
The purpose of this study was to examine differences in pressor response and cardiovagal modulation during isometric handgrip exercise (IHG) between children and adults. Beat-to-beat heart rate (HR)...Full Text Available
Advanced concepts for acceleration
Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)
Advanced concepts for acceleration
1986-07-01
Selected examples of advanced accelerator concepts are reviewed. Such plasma accelerators as plasma beat wave accelerator, plasma wake field accelerator, and plasma grating accelerator are discussed particularly as examples of concepts for accelerating relativistic electrons or positrons. Also covered are the pulsed electron-beam, pulsed laser accelerator, inverse Cherenkov accelerator, inverse free-electron laser, switched radial-line accelerators, and two-beam accelerator. Advanced concepts for ion acceleration discussed include the electron ring accelerator, excitation of waves on intense electron beams, and two-wave combinations. (LEW)
2010-01-01
Background: Steroid administration to accelerate fetal lung maturation reduces neonatal morbidity and mortality in the case of preterm delivery. Behavioral observations suggest effects on fetal cardiovascular regulation. Aim: We hypothesize that beat to beat heart rate variability (fHRV) derived from fetal magnetocardiography (fMCG) will reveal a direct, acute steroidal effect on fetal autonomic heart rate regulation. Subjects: Eight patients between 29 and 34weeks of gestation at risk for preterm birth who were treated with betamethasone (2x12mg within 24h). Study design: Subjects were studied prior to the first and within 6h after the second administration. Continuous fMCG was recorded with a 31-channel-SQUID biomagnetometer. Each dataset was processed by subtracting maternal cardiac art...
Polarization beats in a pillar microcavity
2010-01-01
The beats of the Stokes luminescence parameters in pillar semiconductor microcavities are theoretically analysed. The beats are originated by a slight in-plane anisotropy of the pillar. The influence of the coherence time of exciton polaritons on the decay rate of polarization oscillations of the emission of light by the cavity is revealed. This link is essential for studies of the dynamic properties of polariton condensates in pillar microcavities.
Effect of jaundiced sera and bile salts on cultured beating rat heart cells
1980-01-01
Jaundiced serum, from common bile duct ligated rats, added to cultured heart cells decreased the beating rate and caused an early cessation of beating. Similarly it produced higher levels of lactate in the media. Deoxychloic acid but not cholic acid which are the main bile acids in jaundiced serum caused similar effects, thus suggesting that deoxychloic acid is the toxic substance responsible for heart function alterations seen in severe jaundiced patients.
Energy cascading in the beat-wave accelerator
1987-01-01
A review is given of energy cascading in the beat-wave accelerator. The properties of the electromagnetic cascade and the corresponding plasma-wave evolution are well understood within the framework of an approximate analytic model. Based on this model, idealized laser-plasma coupling efficiencies of the order of 10% do not seem unreasonable. 28 refs.
Development of bench accelerator
1997-09-01
The principle of accelerator and it`s history and new type of accelerator using plasma and laser such as PBWA (Plasma Beat Wave Accelerator), PWFA (Plasma Wake Field Accelerator), LWFA (Laser Wake Field Accelerator), Surfatron accelerator and V{sub p}xB linear accelerator are described. The acceleration length and formation of beam guiding pass of laser accelerator were explained. The applied examples of accelerator are a new treatment for cancer, film surface treatment and a crosslinking reaction of polymers etc.. (S.Y.)
Robust autoresonant excitation in the plasma beat-waveaccelerator: A theoretical study
A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which is based on autoresonant phase-locking of the nonlinear Langmuir wave to the slowly chirped beat frequency of the driving lasers via adiabatic passage through resonance. This new scheme is designed to overcome some of the well-known limitations of previous approaches, namely relativistic detuning and nonlinear modulation or other non-uniformity or non-stationarity in the driven Langmuir wave amplitude, and sensitivity to frequency mismatch due to measurement uncertainties and density fluctuations and inhomogeneities. As in previous schemes, modulational instabilities of the ionic background ultimately limit the useful interaction time, but nevertheless peak electric fields at or approaching the wave-breaking limit seem readily attainable. Compared to traditional approaches, the autoresonant scheme achieves larger accelerating electric fields for given laser intensity, or comparable fields for less laser power; the plasma wave excitation is much more robust to variations or uncertainties in plasma density; it is largely insensitive to the precise choice of chirp rate, provided only that chirping is sufficiently slow; and the quality and uniformity of the resulting plasma wave and its suitability for accelerator applications may be superior. In underdense plasmas, the total frequency shift required is only of the order of a few percent of the laser carrier frequency, and for possible experimental proofs-of-principle, the scheme might be implemented with relatively little additional modification to existing systems based on either solid-state amplifiers and Chirped Pulse Amplification techniques, or, with somewhat greater technological effort, using a CO{sub 2} or other gas laser system.
Robust autoresonant excitation in the plasma beat-waveaccelerator: A theoretical study
2004-11-03
A modified version of the Plasma Beat-Wave Accelerator scheme is introduced and analyzed, which is based on autoresonant phase-locking of the nonlinear Langmuir wave to the slowly chirped beat frequency of the driving lasers via adiabatic passage through resonance. This new scheme is designed to overcome some of the well-known limitations of previous approaches, namely relativistic detuning and nonlinear modulation or other non-uniformity or non-stationarity in the driven Langmuir wave amplitude, and sensitivity to frequency mismatch due to measurement uncertainties and density fluctuations and inhomogeneities. As in previous schemes, modulational instabilities of the ionic background ultimately limit the useful interaction time, but nevertheless peak electric fields at or approaching the wave-breaking limit seem readily attainable. Compared to traditional approaches, the autoresonant scheme achieves larger accelerating electric fields for given laser intensity, or comparable fields for less laser power; the plasma wave excitation is much more robust to variations or uncertainties in plasma density; it is largely insensitive to the precise choice of chirp rate, provided only that chirping is sufficiently slow; and the quality and uniformity of the resulting plasma wave and its suitability for accelerator applications may be superior. In underdense plasmas, the total frequency shift required is only of the order of a few percent of the laser carrier frequency, and for possible experimental proofs-of-principle, the scheme might be implemented with relatively little additional modification to existing systems based on either solid-state amplifiers and Chirped Pulse Amplification techniques, or, with somewhat greater technological effort, using a CO{sub 2} or other gas laser system.
Effect of microwave radiation on the beating rate of isolated frog hearts
1984-01-01
One hundred and two isolated frog hearts were divided into ten groups and placed individually in a waveguide filled with Ringer's solution and exposed to 2,450-MHz CW radiation at 2 and 8.55 W/kg. Heart rate was recorded using one of the following methods: 3-M KCl glass electrode, ultrasound probe, tension transducer, Ringer's solution glass electrode, and a metal wire inserted in the Ringer's solution electrode. An accelerated decrease of heart rate was observed only in those groups recorded using the 3-M KCl electrode and the metal wire Ringer's solution electrode. No effect was found in the other groups. These results indicate that bradycardia in isolated hearts could be caused by electrode artifacts resulting from the intensification of electromagnetic fields.
Accelerated Idioventricular Rhythm: History and Chronology of the Main Discoveries
Accelerated Idioventricular Rhythm (AIVR) is a ventricular rhythm consisting of three or more consecutive monomorphic beats, with gradual onset and gradual termination. It can rarely manifest in patients...Full Text Available
Progress on plasma accelerators
1986-05-01
Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.
1983-06-01
This study was designed to evaluate the effect of cycle length on the parameters of left ventricular function such as left ventricular ejection fraction (LVEF), ejection rates and ejection times. Radionuclide (in vivo sup(99m)Tc-labelled red blood cells) column curves were obtained from ten chacma baboons. Transoesophageal atrial pacing of the baboon hearts was controlled by a microcomputer. A sequence of four beats was generated during arrhythmic pacing, consisting of two beats of equal cycle lengths, followed by a beat 15% shorter and a subsequent beat after a compensatory pause. Triggering impulses were sent to the data processor coincident with one of these beats until sufficient counts were obtained, before advancing to the next beat. Global LVEFs were found to be influenced by the preceding cycle length, increasing on a precious long cycle and decreasing on a previous short cycle and were even found to be influenced one normal beat on from the unrepresentative cycle. Similar trends were found for ejection times and rates. Discarding specific unrepresentative cycle lengths in order to correct for arrhythmia without attention to the previous cycle and even to the following cycle is therefore inappropriate.
Proof-of-principle experiments of laser Wakefield acceleration
Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.
Proof-of-principle experiments of laser Wakefield acceleration
Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.
Proof-of-principle experiments of laser Wakefield acceleration
1994-04-01
Recently there has been a great interest in laser-plasma accelerators as possible next-generation particle accelerators because of their potential for ultra high accelerating gradients and compact size compared with conventional accelerators. It is known that the laser pulse is capable of exciting a plasma wave propagating at a phase velocity close to the velocity of light by means of beating two-frequency lasers or an ultra short laser pulse. These schemes came to be known as the Beat Wave Accelerator (BWA) for beating lasers or as the Laser Wakefield Accelerator (LWFA) for a short pulse laser. In this paper, the principle of laser wakefield particle acceleration has been tested by the Nd:glass laser system providing a short pulse with a power of 10 TW and a duration of 1 ps. Electrons accelerated up to 18 MeV/c have been observed by injecting 1 MeV/c electrons emitted from a solid target by an intense laser impact. The accelerating field gradient of 30 GeV/m is inferred.
Overview of plasma-based accelerator concepts
1996-04-01
An overview is given of the physics issues relevant to the plasma wakefield accelerator, the plasma beat-wave accelerator, the laser wakefield accelerator, including the self-modulated regime, and wakefield accelerators driven by multiple electron or laser pulses. Basic properties of linear and nonlinear plasma waves are discussed, as well as the trapping and acceleration of electrons in the plasma wave. Formulas are presented for the accelerating field and the energy gain in the various accelerator configurations. The propagation of the drive electron or laser beams is discussed, including limitations imposed by key instabilities and methods for optically guiding laser pulses. Recent experimental results are summarized.
Fruit fly's beating heart helps identify human heart disease genes
2006-01-23
In a discovery that could greatly accelerate the search for genetic causes of heart disease, a multi-disciplinary Duke University research team has found that the common fruit fly can serve as a powerful new model for ...
1983-06-01
We perform an analytic study of some quantities relevant to the plasma beat-wave accelerator (PBWA) concept. We obtain analytic expressions for the plasma frequency, longitudinal electron velocity, plasma density and longitudinal plasma electric field of a nonlinear longitudinal electron plasma oscillation with amplitude less than the wave-breaking limit and phase velocity approaching the speed of light. We also estimate the luminosity of a single-pass e/sup +/e/sup -/ linear PBWA collider assuming the energy and collision beamstrahlung are fixed parameters.
Recent progress and perspectives of laser-plasma accelerators
1997-12-31
Recent progress of laser-plasma accelerators has matured a concept of particle acceleration owing to plasma waves excited by laser or electron beams as a possible next generation particle accelerators promising ultrahigh accelerating gradients and a compact size. Four major concepts of laser-plasma accelerators, the plasma beat wave accelerator, the laser wakefield accelerator, the self-modulated laser wakefield accelerator and the plasma wakefield accelerator are reviewed on accelerator physics issues and experiments demonstrating basic mechanisms of their concepts. As a perspective to the future practical application, a design of 5 TeV linear colliders based on the laser wakefield accelerator is discussed. (author)
Automated system for ST segment and arrhythmia analysis in exercise radionuclide ventriculography
1986-06-01
A computer-based system for interpretation of the electrocardiogram (ECG) in the diagnosis of arrhythmia and ST segment abnormality in an exercise system is presented. The system was designed for inclusion in a gamma camera so the ECG diagnosis could be combined with the diagnostic capability of radionuclide ventriculography. Digitized data are analyzed in a beat-by-beat mode and a contextual diagnosis of underlying rhythm is provided. Each beat is assigned a beat code based on a combination of waveform analysis and RR interval measurement. The waveform analysis employs a new correlation coefficient formula which corrects for baseline wander. Selective signal averaging, in which only normal beats are included, is done for an improved signal-to-noise ratio prior to ST segment analysis. Template generation, R wave detection, QRS window size, baseline correction, and continuous updating of heart rate have all been automated. ST level and slope measurements are computed on signal-averaged data. Arrhythmia analysis of 13 passages of abnormal rhythm by computer was found to be correct in 98.4 percent of all beats. 25 passages of exercise data, 1-5 min in length, were evaluated by the cardiologist and found to be in agreement in 95.8 percent in measurements of ST level and 91.7 percent in measurements of ST slope.
2007-01-01
The Holter monitor electrocardiograms were taken from 2 patients with intermittent Wolff-Parkinson-White syndrome. In these patients, when the heart rate was increased, accessory-pathway block on alternate beats was found and was maintained for a considerably long period. In one patient, when accessory-pathway block on alternate beats was found, a ventricular extrasystole occurred. After the long compensatory pause after that extrasystole, a sinus impulse was blocked in the accessory pathway, showing that the effective refractory period of the accessory pathway is markedly long. These findings strongly suggest that alternate sinus impulses fell in the supernormal period of the accessory pathway. An attempt was made to explain the mechanism of accessory-pathway block on alternate beats by u...
Measurement of ventricular function by ECG gating during atrial fibrillation
The assumptions necessary to perform ECG-gated cardiac studies are seemingly not valid for patients in atrial fibrillation (AF). To evaluate the effect of AF on equilibrium gated scintigraphy, beat-by-beat measurements of left-ventricular function were made on seven subjects in AF (mean heart rate 64 bpm), using a high-efficiency nonimaging detector. The parameters evaluated were ejection fraction (EF), time to end-systole (TES), peak rates of ejection and filling (PER,PFR), and their times of occurrence (TPER, TPFR). By averaging together single-beat values of EF, PER, etc., it was possible to determine the true mean values of these parameters. The single-beam mean values were compared with the corresponding parameters calculated from one ECG-gated time-activity curve (TAC) obtained by superimposing all the single-beat TACs irrespective of their length. For this population with slow heart rates, we find that the values for EF, etc., produced from ECG-gated time-activity curves, are very similar to those obtained from the single-beat data. Thus use of ECG gating at low heart rates may allow reliable estimation of average cardiac function even in subjects with AF.
Measurement of ventricular function by ECG gating during atrial fibrillation
1981-03-01
The assumptions necessary to perform ECG-gated cardiac studies are seemingly not valid for patients in atrial fibrillation (AF). To evaluate the effect of AF on equilibrium gated scintigraphy, beat-by-beat measurements of left-ventricular function were made on seven subjects in AF (mean heart rate 64 bpm), using a high-efficiency nonimaging detector. The parameters evaluated were ejection fraction (EF), time to end-systole (TES), peak rates of ejection and filling (PER,PFR), and their times of occurrence (TPER, TPFR). By averaging together single-beat values of EF, PER, etc., it was possible to determine the true mean values of these parameters. The single-beam mean values were compared with the corresponding parameters calculated from one ECG-gated time-activity curve (TAC) obtained by superimposing all the single-beat TACs irrespective of their length. For this population with slow heart rates, we find that the values for EF, etc., produced from ECG-gated time-activity curves, are very similar to those obtained from the single-beat data. Thus use of ECG gating at low heart rates may allow reliable estimation of average cardiac function even in subjects with AF.
Influence of microwaves on the beating rate of isolated rat hearts
1988-01-01
Previous reports have shown that microwave exposure can decrease the beating rate of isolated rat hearts. These experiments were conducted at room temperature and with the hearts exposed to air. We observed arrhythmia frequently at room temperature, and the variation of heart beat was so large that it makes the results difficult to reproduce. Therefore, we employed a double-circulating system to provide perfusion through the coronary artery and around the outside of the heart to maintain the rat hearts at 37.7 degrees C. No arrhythmias were observed in our experiments, and the hearts were beating for at least 1 h. The effects of 16-Hz modulated 2,450-MHz pulsed microwaves (10 microseconds, 100 pps) on the beating rate of 50 isolated rat hearts were studied. Results showed no statistically significant changes of heart rate in exposed groups at SARs of 2 and 10 W/kg compared with the control group. The effect seen at 200 W/kg was shown to be similar to that resulting from heating the heart.
1983-04-01
Laser accelerators may be conveniently characterized, by their mode of operation, into media, far-field, and near-field accelerators. The first category--media accelerators--include the Inverse Cherenkov Effect Accelerator, the Plasma Focus Accelerator, and the Beat Wave Accelerator (BWA). The second category--far-field accelerators--include the Two-Wave Device and the Inverse Free Electron Accelerator (IFEL). The third category--near-field accelerators--includes conventional linacs scaled to small dimensions, dielectric sheets, small holes in dielectric cylinders, and gratings. Attention is devoted to an example from each category: namely (1) the BWA, (2) the IFEL, and (3) the linac scaled to small dimensions (about 30 GHz) and powered by a free electron laser (FEL). Finally, special attention is given to grating accelerators.
Analysis of Gaussian beam and Bessel beam driven laser accelerators
1999-01-01
This paper presents a comparison of Gaussian and Bessel beam driven laser accelerators. The emphasis is on the vacuum beat wave accelerator (VBWA), employing two laser beams of differing wavelengths to impart a net acceleration to particles. Generation of Bessel beams by means of circular slits, holographic optical elements, and axicons is outlined and the image space fields are determined by making use of Huygens close-quote principle. Bessel beams like Gaussian beams experience a Guoy phase shift in the vicinity of a focal region, resulting in a phase velocity that exceeds c, the speed of light in vacuo. In the VBWA, by appropriate choice of parameters, the Guoy phases of the laser beams cancel out and the beat wave phase velocity equals c. The particle energy gain and beam quality are determined by making use of an analytical model as well as simulations. The analytical model ...
Investigation of bunch repetition rate deviations in FIR FEL driven by a magnetron-based microtron
The stability of the bunch repetition rate in a FIR FEL driven by a 2.8 GHz magnetron-based microtron was investigated using a heterodyne method with a low Q-factor straight-flight measuring cavity. The measuring cavity is located in the straight section of the FIR FEL injection beam line and is excited by the passage of electron bunches. The RF signal from the measuring cavity coupling loop was mixed with a precise heterodyne signal with a frequency difference of several MHz. The beat frequency was analyzed to obtain the temporal distribution of the bunch repetition rate deviation during the macro pulse of the electron beam. The time resolution and the accuracy of measurements are approximately 100 ns and a few kHz, respectively. Based on this data, we could determine the level and shape of the magnetron current and the initial frequency shift between magnetron and accelerating cavity for the FEL operation in the wavelength range 100-300 microns.
1994-01-01
Electron acceleration by electrostatic fields produced in plasmas by short, intense laser pulses have been studied in two groups of papers. The first group is concerned with the Plasma Beat Wave Acceleration (PBWA) where the resonance excitation of a longitudinal wave and the electron acceleration of this wave occurs during the propagation of two relatively long laser pulses with different frequencies in the plasma. The second group of papers refers to the problem of the Laser Wake Field Accelerator (LWFA), where a longitudinal wave is created by ultrashort, intense laser pulses. A brief synopsis and comparison of the two groups of papers are presented.
Collective acceleration of protons by the plasma waves in a counterstreaming electron beam
A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the trapping threshold can be dramatically reduced so as to admit the possibility for proton acceleration.
Collective acceleration of protons by the plasma waves in a counterstreaming electron beam
1987-03-01
A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the trapping threshold can be dramatically reduced so as to admit the possibility for proton acceleration.
Particle acceleration by ultra-intense laser-plasma interactions
The mechanism of particle acceleration by ultra-increase laser-plasma interaction is explained. Laser light can generate very high electric field by focusing with electromagnetic field matched phase with frequency. 1018 W/cm sup 2 laser light produce about 3 TV/m electric field. Many laser accelerators, which particle acceleration method satisfies phase matching particle and electric field, are proposed. In these accelerators, the Inverse Cherenkov Accelerator, Inverse FEL Accelerator and Laser-Plasma Accelerator are explained. Three laser-plasma acceleration mechanisms: Plasma Beat Wave Accelerator, Laser Wake-Field Accelerator (LWFA) and Self-Modulated LWFA, showed particle acceleration by experiments. By developing a high speed Z pinch capillary-plasma optical waveguide, 2.2 TW and 90 fs laser pulse could be propagated 2 cm at 40 mu m focusing radius in 1999. Dirac acceleration or ultra-relativistic ponderomotive acceleration mechanism can increase energy exponentially. (S.Y.)
Collective acceleration of protons by the plasma waves in a counterstreaming electron beam
1987-01-01
A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator with as magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a loner and tunable plasma wavelength, a longer pump depleting length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Therefore, the energy gain of the driven particles can be greatly enhanced ...
Collective acceleration of protons by the plasma waves in a counterstreaming electron beam
1987-01-01
A novel advanced accelerator is proposed. The counterstreaming electron beam accelerator relies on the same physical mechanism as that of the plasma accelerator but replaces the stationary plasma in the plasma accelerator by a magnetized relativistic electron beam, drifting antiparallel to the driving source and the driven particles, as the wave supporting medium. The plasma wave in a counterstreaming electron beam can be excited either by a density-ramped driving electron beam or by properly beating two laser beams. The fundamental advantages of the counterstreaming electron beam accelerator over the plasma accelerator are a longer and tunable plasma wavelength, a longer pump depletion length or a larger transformer ratio, and easier pulse shaping for the driving source and the driven beam. Thus the energy gain of the driven particles can be greatly enhanced whereas the ...
2010-01-01
We proposed a new acquisition method of coronary multidetector-row CT (MDCT) achieved by pacing rate resetting and/or propranolol or verapamil injection in patients with a pacemaker. Coronary MDCT was undertaken in 57 patients with a pacemaker (DDD: 51, VVI: 6) and in 2975 patients with sinus rhythm as control using Aquilion 64 (Toshiba). Pacing rate was reset to 60 beats per minute (bpm) in DDD, and spontaneous beats were suppressed by propranolol injection. Pacing rate was reset to 70 bpm in atrial fibrillation with VVI, and spontaneous beats were suppressed by verapamil injection. Coronary MDCT was undertaken using as high a beam pitch (BP) as possible. When spontaneous beats were not suppressed, we selected the optimal gantry speed and BP to get the highest temporal resolution. Image quality makes no significant difference between pacemaker and sinus rhythm. When ...
2010-01-01
Abstract Background aims. Heart failure therapy with human embryonic stem cell (hESC)-derived cardiomyocytes (hCM) has been limited by the low rate of spontaneous hCM differentiation. As others have shown that p38 mitogen-activated protein kinase (p38MAPK) directs neurogenesis from mouse embryonic stem cells, we investigated whether the p38MAPK inhibitor, SB203580, might influence hCM differentiation. Methods. We treated differentiating hESC with SB203580 at specific time-points, and used flow cytometry, immunocytochemistry, quantitative real-time (RT)-polymerase chain reaction (PCR), teratoma formation and transmission electron microscopy to evaluate cardiomyocyte formation. Results. We observed that the addition of inhibitor resulted in 2.1-fold enrichment of spontaneously beating human ...
2010-01-01
We study the effects of the semiconductor laser noise on the generated beat signal, in Coherent Optical Domain Reflectometry device. By using a general laser noise analytical model, based on Volterra non-linear treatment of laser rate equations, we find a novel general expression of the beat photocurrent. We show that the coherence and the incoherence cases are observed for a different delay time intervals than the ones known in literature. We show that the coherence domain corresponds to a delay time lower than the half of the laser coherence time Formula Not Shown , and the incoherence domain corresponds for Formula Not Shown . An original shape of the beat signal autocorrelation function affected by the laser noises is obtained.
Parameter choice for a laser beat-wave accelerator
1988-07-01
The three-wave interaction in a laser beat-wave accelerator is studied. We find that with the parameters of sigma = ..omega../sub p//(..omega../sub 1/-..omega../sub 2/) and ..beta.. = ..omega../sub 2//..omega../sub 1/ properly chosen (where ..omega../sub p/, ..omega../sub 1/, and ..omega../sub 2/ are the plasma frequency and frequencies of the two laser beams, respectively), the required large-amplitude plasma wave will be excited even though the incident laser beams are relatively weak; as a result, the injected electrons will obtain a significant energy gain.
1984-02-01
This study set out to determine the pathophysiologic changes in the left ventricle during atrial pacing in 22 patients with coronary artery disease. Graduated right atrial pacing to a rate of 160 beats/min, or the induction of angina pectoris or significant ST depression was undertaken. Ventricular volumes were measured at rest and at rates of 100, 120, 140 and 160 beats/min using radionuclide angiography. The volumes at a pacing rate of 100 beats/min were used as a reference standard (100%). In the 22 patients with coronary artery disease, left ventricular end-diastolic volume decreased from 118 +/- 3% at rest to 80 +/- 5% at a rate of 160 beats/min; stroke volume from 121 +/- 3% to 54 +/- 5%; and ejection fraction (EF) from 49 +/- 3% to 37 +/- 5%. End-systolic volume decreased from 118 +/- 4% at rest, reached its minimal value of 94 +/- 5% at a rate of 120 beats/min and then increased slightly to 106 +/- 9% at 160 beats/min. Cardiac output and blood pressure did not change significantly. Compared to the control group of 10 normal subjects, the patients had a significantly smaller decrease in end-diastolic volume and end-systolic volume than in normal control subjects. EF in the normal subjects did not change. Blood pressure, cardiac output and stroke volume were similar in both groups. Atrial pacing tachycardia induced reversible ventricular dysfunction with a decrease in EF. Stroke volume was maintained because of relative ventricular dilatation.
Fractal correlation of heart rate variability in obese children
2010-01-01
Background: The loss of variability and fractal properties in the heart rate is related to greater morbidity and mortality rates. Objective: The aim of the present study was to analyze heart rate dynamics in obese children by measuring short and long-term fractal exponents and heart rate variability (HRV) indices. Materials and methods: 112 male and female children aged 8 to 12years were divided into two groups based on body mass index: obese (n=51) and normal weight range (n=61). Heart rate was monitored beat-to-beat in the dorsal decubitus position for 20min, analyzing the low frequency (LF) and high frequency (HF) spectral indices in normalized units and ms^2 as well as short and long-term fractal exponents (alpha-1 and alpha-2) of the detrended fluctuation analysis (DFA). The non-paire...
2010-01-01
Acute papillary muscle rupture results in severe mitral regurgitation and hemodynamic instability, and it carries a poor prognosis with a high mortality rate. We present a case of an 86-year-old woman affected by mitral regurgitation due to an acute posterior papillary muscle rupture. The patient underwent a mitral valve repair with annuloplasty and artificial chordae implantation. The neochorda was sutured to the posterior mitral leaflet and fixed through the left ventricle wall on the epicardium. The neochorda length was determined on the beating heart under echocardiographic view.
Long range anticorrelations and non-gaussian behavior of a leaky faucet
1995-07-25
We find that intervals between successive drops from a leaky faucet display scale-invariant, long-range anticorrelations characterized by the same exponents of heart beat-to-beat intervals of healthy subjects. This behavior is also confirmed by numerical simulations on lattice and it is faucet-width- and flow-rate-independent. The histogram for the drop intervals is also well described by a L\\'evy distribution with the same index for both histograms of healthy and diseased subjects. This additional result corroborates the evidence for similarities between leaky faucets and healthy hearts underlying dynamics.
Virtual Accelerator for Accelerator Optics Improvement
2005-09-30
Through determination of all quadrupole strengths and sextupole feed-downs by fitting quantities derivable from precision orbit measurement, one can establish a virtual accelerator that matches the real accelerator optics. These quantities (the phase advances, the Green's functions, and the coupling ellipses tilt angles and axis ratios) are obtained by analyzing turn-by-turn Beam Position Monitor (BPM) data with a model-independent analysis (MIA). Instead of trying to identify magnet errors, a limited number of quadrupoles are chosen for optimized strength adjustment to improve the virtual accelerator optics and then applied to the real accelerator accordingly. These processes have been successfully applied to PEP-II rings for beta beating fixes, phase and working tune adjustments, and coupling reduction to improve PEP-II luminosity.
The generation of high fields for particle acceleration to very high energies. Proceedings
1985-01-01
A Workshop organised by the CERN Accelerator School, the European Committee for Future Accelerators and the Istituto Nazionale di Fisica Nucleare was held at the Frascati laboratory of INFN during the last week of September 1984. Its purpose was to bring together an inter-disciplinary group of physicists to review ideas for the acceleration of particles to energies beyond those attainable in machines whose construction is underway, or is currently contemplated. These proceedings contain some of the material presented and discussed at the Workshop, comprising papers on topics such as: the free-electron-laser, the lasertron, wakefield accelerators, the laser excitation of droplet arrays, a switched-power linac, plasma beat-wave accelerators and the choice of basic parameters for linear colliders intended for the TeV energy region. (orig.)
Free wave laser acceleration of electrons and consequences for the Umstadter experiment
1997-01-01
In contrast to electron acceleration by lasers due to plasma effects (beat wave etc.) the laser acceleration of electrons in vacuum (free wave accelerator) has been established as a pure Lorentz force mechanism. This indeed leads to the same acceleration as the pondermotive potential though it is mainly based on an incomplete phase description of the quiver motion and on general phase-, intensity- and exact field-conditions of the complete theory. It is remarkable that the result of the Umstadter experiment producing 108 30 MeV-electrons within a cone of 14 degrees of the beam direction by firing a 25 TW-400-fs Nd-glass laser pulse on a gas puff can be reproduced completely. The theory of the free wave acceleration yields the same electron number as measured. A similar cone angle and an electron energy of 30 MeV if the longitudinal optical field is included while the ...
2010-01-01
Abstract Background: Dynamic cerebral autoregulation (dCA), the process by which the cerebral blood flow (CBF) is normally maintained relatively constant despite fluctuations in beat-to-beat blood pressure (BP), is impaired acutely following major ischaemic stroke. It is uncertain if dCA is impaired acutely after mild ischaemic stroke or transient ischaemic attack (TIA). We assessed dCA in patients acutely and sub-acutely following TIA or mild ischaemic stroke. Methods: Nineteen consecutive mild ischaemic stroke patients and 17 consecutive TIA patients underwent recordings of beat-to-beat BP, cerebral blood flow velocity (bilateral transcranial Doppler insonation of the middle cerebral artery) and heart rate a median of 36 h from onset and again a median of 96 h from onset. Dynamic autoreg...
Linear and Chromatic optics measurements at RHIC
Measurements of chromatic beta-beating were carried out for the first time in the RHIC accelerator during Run 2009. The analysis package developed for the LHC was used to extract the off-momentum optics for injection and top energy. Results from the beam experiments and compassion to the optics model are presented.
Improvement of PEP-II Linear Optics with a MIA-Derived Virtual Accelerator
2006-08-30
In several past studies, model independent analysis, in conjunction with a virtual accelerator model, has been successful in improving PEP-II linear geometric optics. In many cases, optics improvement yielded an increase in machine luminosity. In this study, an updated characterization of linear optics is presented. With the PEP-II beam position monitor (BPM) system, four independent beam centroid orbits were extracted and used to determine phase advances and linear Green's functions among BPM locations. A magnetic lattice model was then constructed with a singular value decomposition-enhanced least-square fitting of phase advances and Green's functions, which are functions of quadrupole strengths, sextupole feed-downs, as well as BPM errors, to the corresponding measured quantities. The fitting process yielded a machine model that matched the measured linear optics of the real machine and was therefore deemed the virtual accelerator. High beta beat, as well as linear coupling, was observed in both LER and HER of the virtual accelerator. Since there was higher beta beating in LER, focus was shifted to the improvement of this ring. By adjusting select quadrupoles of the virtual LER and fitting the resulting beta functions and phase advances to those of the desired lattice, the average beta beat of the virtual machine was effectively reduced. The new magnet configuration was dialed into LER on August 10, 2006, and beta beat was reduced by a factor of three. After fine tuning HER to match the improved LER for optimal collision, a record peak luminosity of 12.069 x 10{sup 33} cm{sup -2} s{sup -1} was attained on August 16, 2006.
As can be seen this was an extremely productive period with the PI and his team completing all the tasks in the original proposal. The following six pages list the work statement as it appeared in the initial proposal. Next to it is a summary of what the actual performance was. A check mark means the accomplishment was exactly as planned in the work statement. A list of key publications under each main subtask in the work statement are also listed.
1994-12-31
As can be seen this was an extremely productive period with the PI and his team completing all the tasks in the original proposal. The following six pages list the work statement as it appeared in the initial proposal. Next to it is a summary of what the actual performance was. A check mark means the accomplishment was exactly as planned in the work statement. A list of key publications under each main subtask in the work statement are also listed.
Excitation of a large amplitude plasma wave by a short laser pulse
1990-01-01
In the ''Laser Wakefield Accelerator'' scheme a large amplitude electron plasma wave is excited by a single laser pulse, with some important advantages on the beat-wave and particle wake-field schemes. For the case of very short laser pulses (femtoseconds), the plasma wave can possibly grow to even larger amplitudes due to Raman forward scattering inside the pulse broad frequency spectrum. (orig.).
Does anything beat doing nothing?
1992-01-01
Experience at more than 180 generating stations (including one-fourth of the commercially operating nuclear stations) with a total of more than $1 billion of inventory has shown that 40% of the on-hand inventory value is in excess of the amount required to meet availability objectives. The methodology for determining these proper stocking quantities was the subject of a previous paper. This paper addresses a process for determining the most economical course of action to accelerate the reduction of excess stocks
Does anything beat doing nothing
1992-01-01
Experience at more than 180 generating stations (including one-fourth of the commercially operating nuclear stations) with a total of more than $1 billion of inventory has shown that 40% of the on-hand inventory value is in excess of the amount required to meet availability objectives. The methodology for determining these proper stocking quantities was the subject of a previous paper. This paper addresses a process for determining the most economical course of action to accelerate the reduction of excess stocks.
Exercise thallium imaging in patients with diabetes mellitus. Prognostic implications
1987-02-01
We used exercise thallium 201 imaging in 123 patients with diabetes mellitus (77 men and 46 women, aged 56 +/- 8 years), 75% of whom had angina pectoris (typical or atypical). During exercise testing, 18 patients (15%) had angina pectoris, 28 (23%) had ischemic ST changes, and 69 (56%) had abnormal thallium images. During follow-up (up to 36 months), there were 12 cardiac events; four patients died of cardiac causes and eight had nonfatal acute myocardial infarction. Univariate and multivariate survival analysis identified two independent predictors of cardiac events: the event rate was significantly less in patients with normal images and exercise heart rate over 120 beats per minute than in patients with abnormal images and exercise heart rate of 120 beats per minute or less (0% vs 22%). The patients with abnormal images or exercise heart rate of 120 beats per minute or less had an intermediate event rate (11.5%). Furthermore, two of the 54 patients with normal images and ten of 69 patients with abnormal images had subsequent cardiac events. Thus, exercise thallium imaging is useful in risk stratification in patients with diabetes mellitus.
Plasma-based acceleration concepts
1997-03-01
This paper reviews the experimental progress made towards plasma-based accelerators since the last Advanced Accelerator Concepts Workshop at Lake Geneva in June, 1994. It has been a very productive two years, with many new experimental results from all over the world. The latest results from the Plasma Beat Wave, Laser Wakefield, and Plasma Wakefield Accelerator concepts will be reviewed. The explosion of results from the instability-driven or self-modulated Laser Wakefield Accelerator experiments will be reviewed as well as such enabling technologies as plasma channel formation which is necessary to guide laser pulses over long distances. {copyright} {ital 1997 American Institute of Physics.}
Autonomic response to upright tilt in people with and without Down syndrome
2010-01-01
This study examined whether the autonomic response to passive upright tilt as evidenced by changes in measures of heart rate and blood pressure variability differs between individuals with DS and without DS. Beat-to-beat blood pressure was measured in 26 individuals with Down syndrome (DS) and 11 individuals without DS during 5min of rest and 5min of upright tilt. Dependent variables included heart rate, blood pressure, frequency component measures of heart rate and blood pressure variability, and baroreflex sensitivity. The normalized high frequency (HF) power, normalized low frequency (LF) power, and LF/HF of heart rate variability, as well as the LF of blood pressure variability were reduced in persons with DS in response to upright tilt (p
Forecasting exchange rates using local regression
2010-01-01
In this article we use a generalization of the standard nearest neighbours, called local regression (LR), to study the predictability of the yen/US$ and pound sterling/US$ exchange rates. We also compare our results with those previously obtained with global methods such as neural networks, genetic programming, data fusion and evolutionary neural networks. We want to verify if we can generalize to the exchange rate forecasting problem the belief that local methods beat global ones.
Comparison of a theoretical impedance model with experimental measurements of pulsatile blood flow
2007-01-01
The velocity dependent changes in the impedance of flowing blood have been widely reported in the literature. These changes have been suggested as a source of the impedance change of the thorax measured during Impedance Cardiography techniques. In this study, a theoretical model incorporating red blood cell orientation, was developed to predict the impedance of pulsatile blood as it flows through rigid tubes. Experimental measurements were recorded for comparisons with the theoretical model. Bovine blood was pumped through rigid tubes in a mock circulatory system and its impedance and velocity were measured. Experimental and theoretical impedance and velocity waveforms are presented for a range of cardiac parameters such as pulse rate, stroke volume and systolic/ diastolic ratio. Comparisons show that the theoretical model successfully simulated features of the experimental waveforms. These were: 1) a difference between impedance during accelerating and decelerating flow at the same velocity, 2) an instantaneous impedance response to acceleration, and 3) a decay in impedance during deceleration to zero flow. Both the modelled and experimental impedance data also indicate a good cross correlation with the velocity (r=0.73 and 0.65 respectively at a pulse rate of 70 beats per minute). Publisher: Springer Contributor: Scharfetter, Hermann; Merwa, Robert Relation: DOI:10.1007/978-3-540-73841-1_11; Gaw, Richelle L. and Cornsih, Bruce H. and Thomas, Brian J. (2007) Comparison of a theoretical impedance model with experimental measurements of pulsatile blood flow. In: 13th International Conference on Electrical Bioimpedance and the 8th Conference on Electrical Impedance Tomography ICEBI 2007, August 29th - September 2nd 2007, Graz, Austria. Format: application/pdf Rights: Copyright 2007 Springer; This is the author-version of the work. Conference proceedings published, by Springer Verlag, will be available via SpringerLink. http://www.springerlink.com SpringerLink
[Case of thyroid crisis with persistent tachycardia diagnosed postoperatively]
A 35-year-old man with multiple bone fractures underwent an emergency operation. On arriving at the operating room, his heart rate was 160 beats x min(-1), and blood pressure was 100/50 mmHg. We anesthetized him with oxygen, sevoflurane, fentanyl and remifentanil. We suspected hypovolemia, and treated him with crystalloid and transfused red cells and fresh frozen plasma so that heart rate and blood pressure could be stabilized. Tachycardia of 140 beats x min(-1) persisted, and landiolol was continuously administered at a rate of 5-10 mg x hr(-1) after a 2.5 mg bolus injection. Heart rate became controlled around 120 beats x min(-1) without hypotension during anesthesia. Finally, we noticed thyroid crisis in this case, and diagnosed it with laboratory data after operation. We should be aware that atypical tachycardia is caused by thyroid crisis.
SYNCHROTRON RADIO FREQUENCY PHASE CONTROL SYSTEM
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)
Interactions between heart rate variability and pulmonary gas exchange efficiency in humans
2010-01-01
The respiratory component of heart rate variability (respiratory sinus arrhythmia, RSA) has been associated with improved pulmonary gas exchange efficiency in humans via the apparent clustering and scattering of heart beats in time with the inspiratory and expiratory phases of alveolar ventilation, respectively. However, since human RSA causes only marginal redistribution of heart beats to inspiration, we tested the hypothesis that any association between RSA amplitude and pulmonary gas exchange efficiency may be indirect. In 11 patients with fixed-rate cardiac pacemakers and 10 healthy control subjects, we recorded R-R intervals, respiratory flow, end-tidal gas tension and the ventilatory equivalents for carbon dioxide Formula Not Shown and oxygen Formula Not Shown during `fast' (0.25 Hz)...
2010-01-01
Based on cortisol release, a variety of situations to which domestic horses are exposed have been classified as stressors but studies on the stress during equestrian training are limited. In the present study, Warmblood stallions (n=9) and mares (n=7) were followed through a 9 respective 12-week initial training program in order to determine potentially stressful training steps. Salivary cortisol concentrations, beat-to-beat (RR) interval and heart rate variability (HRV) were determined. The HRV variables standard deviation of the RR interval (SDRR), RMSSD (root mean square of successive RR differences) and the geometric means standard deviation 1 (SD1) and 2 (SD2) were calculated. Nearly each training unit was associated with an increase in salivary cortisol concentrations (p
Particle acceleration by plasma
Plasma acceleration is carried out by using potential of plasma wave. It is classified by generation method of plasma wave such as the laser wake-field acceleration and the beat wave acceleration. Other method using electron beam is named the plasma wake-field acceleration (or beam wake-field acceleration). In this paper, electron acceleration by laser wake-field in gas plasma, ion source by laser radiation of solid target and nanoion beam generation by one component of plasma in trap are explained. It is an applicable method that ions, which run out from the solid target irradiated by laser, are used as ion source of accelerator. The experimental system using 800 nm laser, 50 mJ pulse energy and 50 fs pulse width was studied. The laser intensity is 4x10 sup 1 sup 6 Wcm sup - sup 2 at the focus. The target film of metal and organic substance film was used. When laser irradiated Al target, two particles generated, in front and backward. It is new fact that the neutral particle was obtained in front, because it did not sensitive to magnet. Electron accelerated by laser wake-field and nano-ion beam source are explained. (S.Y.)
2010-01-01
Aim: Aim of this retrospective study was to analyze the effect of closed-loop stimulation (CLS) and DDD pacing mode on autonomic balance, and to evaluate heart rate variability (HRV) during CLS stimulation. Methods and Materials: Autonomic balance was estimated by a 24-hour HRV analysis of paced and spontaneous beats in patients implanted with a dual-chamber pacemaker (Inos2+ CLS-Biotronik GmbH, Berlin, Germany) and randomly assigned to CLS or DDD pacing mode. Patients underwent two 24-hour electrocardiogram Holter recordings at the end of each 3-month pacing mode period. Each Holter recording was automatically scanned to extract sequences of consecutive beats of the same type [atrial paced (Ap)-sequence and atrial spontaneous (As)-sequence], lasting at least 130 beats. Results: Eight hund...
Moving with the beat: heart rate and visceral temperature of free-swimming and feeding bluefin tuna
2008-12-22
Full Text Available.Owing to the inherent difficulties of studying bluefin tuna, nothing is known of the cardiovascular function of free-swimming fish. Here, we surgically implanted newly designed data loggers into the visceral cavity of juvenile southern bluefin tuna (Thunnus maccoyii) to measure changes in the heart rate (f
How random is your heart beat?
2006-11-14
We measure the content of random uncorrelated noise in heart rate variability using a general method of noise level estimation using a coarse grained entropy. We show that usually - except for atrial fibrillation - the level of such noise is within 5 - 15% of the variance of the data and that the variability due to the linearly correlated processes is dominant in all cases analysed but atrial fibrillation. The nonlinear deterministic content of heart rate variability remains significant and may not be ignored.
Discrete Scale Invariance in the Cascade Heart Rate Variability Of Healthy Humans
2004-11-04
Evidence of discrete scale invariance (DSI) in daytime healthy heart rate variability (HRV) is presented based on the log-periodic power law scaling of the heart beat interval increment. Our analysis suggests multiple DSI groups and a dynamic cascading process. A cascade model is presented to simulate such a property.
Increased heart rate variability and executive performance after aerobic training in the elderly
2010-01-01
This study examined the effects of two short physical training programs on various parameters of heart rate variability (HRV) and on executive performance in older people. Twenty-four sedentary men and women aged 6578years were randomly assigned to an aerobic exercise program or a stretching program three times a week for 12weeks. Resting HRV was measured in time and frequency domains in each participant before and after the 12-week programs. Executive performance was measured with the Wisconsin card sorting test (WCST). Significant groupsession interactions emerged for the standard deviation of normal beat-to-beat (RR) intervals, the root-mean-square of successive RR, and high frequency power. Only the aerobic training group increased vagal-mediated HRV parameters. Moreove...
Effects of water soluble crude oil fractions on cirral beat frequency in Balanus balanoides
1988-11-01
Many previous investigations on the effect of crude oil on animals considered rates of survival. More important are studies of sublethal effects of oil on physiological processes especially in long-term pollution with low quantities of oil. Crude oil may reduce food intake and growth, rates of oxygen consumption, and motile behavior such as swimming and burrowing. Degradation in sensory acuity and in behavioral responses to sensory cues have also been reported. In the present preliminary investigation the influence of water-soluble fractions of crude oil from Venezuela (Cabimas) and Saudi Arabia (Arabian-light) on cirral activity of Balanus balanoides was studied. Cirral beat reflects the general metabolic level of the barnacle and may be a suitable indicator for sublethal pollution effects on the organism.
2010-01-01
The CellDrum technology (The term CellDrum technology includes a couple of slightly different technological setups for measuring lateral mechanical tension in various types of cell monolayers or 3D-tissue constructs) was designed to quantify the contraction rate and mechanical tension of self-exciting cardiac myocytes. Cells were grown either within flexible, circular collagen gels or as monolayer on top of respective 1-m thin silicone membranes. Membrane and cells were bulged outwards by air pressure. This biaxial strain distribution is rather similar the beating, blood-filled heart. The setup allowed presetting the mechanical residual stress level externally by adjusting the centre deflection, thus, mimicking hypertension in vitro. Tension was measured as oscillating differential...
Studies of relativistic wave-particle interactions in plasma-based collective accelerators
1990-01-01
The interaction of externally injected charged particles (electrons) with plasma waves moving with a phase velocity that is very close to the speed of light is examined. Such plasma waves form the basis of at least three collective accelerator schemes: the plasma beat wave accelerator (PBWA), the plasma wake-field accelerator (PWFA), and the laser wake-field accelerator (LWFA). First, the electron trapping threshold, energy gain and acceleration length are examined using a 1-D model. This model elucidates how the final energies of the injected test electrons depend upon their injection and extraction phases and phase slippage. Phase energy diagrams are shown to be extremely useful in visualizing wave-particle interactions in 1-D. Second, using a two-dimensional model, the effects of radial electric fields on focusing or defocusing the injected particles depending upon their radial positions and phases in the relativistically moving potential well are examined. Finally, the model is extended to 3-D so that the effect of injected particles' emittance on the acceleration process may be determined. This simple 3-D model will be extremely useful in predicting the electron energy spectra of several current experiments designed to demonstrate ultrahigh gradient acceleration of externally injected test particles by relativistic plasma waves. (author).
Realtime Multichannel System for Beat to Beat QT Interval Variability
The measurement of beat-to-beat QT interval variability (QTV) shows clinical promise for identifying several types of cardiac pathology. However, until now, there has been no device capable of displaying, in real time on a ...
Modelling a Parasystolic Rhythm in a Heart Transplanted Patient
A parasystole from a heart transplanted patient was analysed via the beat to beat - RR interval time series obtained from the electrocardiogram (ECG). The dysrhythmia, resulting from the coexistence of two pacemakers, the sinus node and an ectopic focus, presents distinctive regular patterns with transitions from one pattern to another occurring abruptly. It is shown that the parasystolic rhythm can be simulated by a model involving two oscillators firing at fixed rates, under the restriction that neither is allowed to fire during the other's refractory period. We found that the structure of the generated RR time series is essentially determined by the ratio of the period of the two oscillators. In the case of the heart transplanted patient that has a small heart rate variability as a result of heart denervation, the model could predict the sequence of RR intervals over a considerable period of time (~ 80 beats with an error < 6%). From a physiological point of view, our results imply that the interaction between the two pacemakers in the heart is fairly weak, and hence the parasystole observed in the heart transplanted patient can be modelled as a "pure" parasystole.
1. The changes in cardiac output and mean right atrial pressure (R.A.P.) evoked by stimulation of the cardiac autonomic nerves were investigated in cats under chloralose anaesthesia, with unopened chests and spontaneous respiration, and with active vascular reflexes. Cardiac output was measured by thermal dilution; the technique used was calibrated against the direct Fick method. 2. The initial values of R.A.P. and output were varied by infusion of dextran-saline solution followed by withdrawal of blood. At positive values of R.A.P. withdrawal of blood caused a fall in R.A.P. with no change in cardiac output. At negative R.A.P. blood withdrawal caused a fall in output with little change in R.A.P.: the linear regression coefficient for output on R.A.P. was 48·2 ml./min.kg.mmHg (S.E. 2·06, n = 63, nine cats). 3. Stimulation of the right cardiac sympathetic nerve increased heart rate by 69·2 beats/min (S.E. 4·0) from the resting rate of 158 beats/min (S.E. 6·3, ten cats). The acceleration was accompanied in most instances by a rise in cardiac output and a fall in R.A.P. and the magnitude of the rise in output was related to that of the fall in R.A.P. 4. In no experiment could R.A.P. be reduced below -2·5 mmHg either by withdrawal of blood or by sympathetic stimulation. At negative values of R.A.P. the fall in R.A.P. and rise in output evoked by sympathetic stimulation were small; substantial changes could be obtained only from positive initial values of R.A.P. The proportional increase in output evoked by a given proportional increase in heart rate during near-maximal sympathetic stimulation had a linear relationship to the initial value of R.A.P. over the range -2 to +8 mmHg. The output increment was less than proportional to the rate increment at all values of R.A.P. below +3 mmHg. 5. In five experiments stimulation of the left cardiac sympathetic nerve evoked a greater increase in output for a given increase in heart rate than did stimulation of the right nerve; on the other hand both nerves gave similar increments of output for a given fall in R.A.P. 6. Stimulation of the distal end of the right vagus nerve slowed the heart and caused a fall in cardiac output and a rise in R.A.P. The change in output associated with a given change in R.A.P. was significantly greater (P = 0·05) during sympathetic than during vagal stimulation in 14 out of 18 tests; the difference increased as circulating volume was reduced. 7. It is concluded that the relationship between cardiac output and R.A.P. during sympathetic and vagal stimulation is consistent with the hypothesis that neurally evoked changes in cardiac performance vary output mainly, but not exclusively, by inducing changes in R.A.P. which alter the pressure gradient for the return of blood to the right atrium from the periphery.
2007-01-01
The jeju is a teleost fish with bimodal respiration that utilizes a modified swim bladder as an air-breathing organ (ABO). Like all air-breathing fish studied to date, jeju exhibit pronounced changes in heart rate (f(H)) during air-breathing events, and it is believed that these may facilitate oxygen uptake (M-O2) from the ABO. The current study employed power spectral analysis (PSA) of f(H) patterns, coupled with instantaneous respirometry, to investigate the autonomic control of these phenomena and their functional significance for the efficacy of air breathing. The jeju obtained less than 5% of total M-O2 (M-tO2) from air breathing in normoxia at 26 degrees C, and PSA of beat-to-beat variability in fH revealed a pattern similar to that of unimodal water-breathing fish. In deep aquatic hypoxia (water P-O2=1 kPa) the jeju increased the frequency of air breathing (f(AB)) tenfold and maintained M-tO2 unchanged from normoxia. This was associated with a significant increase in heart rate variability (HRV), each air breath (AB) being preceded by a brief bradycardia and then followed by a brief tachycardia. These f(H) changes are qualitatively similar to those associated with breathing in unimodal air-breathing vertebrates. Within 20 heartbeats after the AB, however, a beat-to-beat variability in f(H) typical of water-breathing fish was re-established. Pharmacological blockade revealed that both adrenergic and cholinergic tone increased simultaneously prior to each AB, and then decreased after it. However, modulation of inhibitory cholinergic tone was responsible for the major proportion of HRV, including the precise beat-to-beat modulation of f(H) around each AB. Pharmacological blockade of all variations in f(H) associated with air breathing in deep hypoxia did not, however, have a significant effect upon f(AB) or the regulation of M-tO2. Thus, the functional significance of the profound HRV during air breathing remains a mystery. Publisher: The Company of Biologists Ltd Contributor: Hoppeler, H. Coverage: 2007-01-01T00:00:00Z
Ultra-intense Laser Applications to the Industries at GPI
2009-01-01
The laser accelerator provides us not only ultra high field, but also extremely short pulse radiation sources, the laser-produced X-rays. Using a 1.2 TW table-top Ti:sap laser, we are pursuing the activities for the industrial application. First we proposed a new injection acceleration scheme using the ultra short beat-wave accelerator for the economical radiation source. Then we proposed two applications both on the backward see-through vision of distant objects using the laser X-rays, and on the X-ray illumination on Aspergillus awamori spores, which is 100 times effective of the current X-ray tube cases
Standing-Wave Free-Electron Laser Two-Beam Accelerator
A free-electron laser (FEL) two-beam accelerator (TBA) is proposed, in which the FEL interaction takes place in a series of drive cavities, rather than in a waveguide. Each drive cavity is 'beat-coupled' to a section of the accelerating structure. This standing-wave TBA is investigated theoretically and numerically, with analyses included of microwave extraction, growth of the FEL signal through saturation, equilibrium longitudinal beam dynamics following saturation, and sensitivity of the microwave amplitude and phase to errors in current and energy. It is found that phase errors due to current jitter are substantially reduced from previous versions of the TBA. Analytic scalings and numerical simulations are used to obtain an illustrative TBA parameter set.
Methods used in WARP3d, a three-dimensional PIC/accelerator code
1997-01-01
WARP-3d(1,2), a three-dimensional PIC/accelerator code, has been developed over several years and has played a major role in the design and analysis of space-charge dominated beam experiments being carried out by the heavy-ion fusion programs at LLNL and LBNL. Major features of the code will be reviewed, including: residence corrections which allow large timesteps to be taken, electrostatic field solution with subgrid scale resolution of internal conductor boundaries, and a beat beam algorithm. Emphasis will be placed on new features and capabilities of the code, which include: a port to parallel processing environments, space-charge limited injection, and the linking of runs covering different sections of an accelerator. Representative applications in which the new features and capabilities are used will be presented along with the important results
2010-01-01
The localized electrostatic eigenmodes of a plasma with parabolic density profile in the presence of azimuthal magnetic field are investigated in the slab model by taking stepwise variations in plasma density and magnetic field. The mode amplitude is maximum where magnetic field is maximum. A mode can be resonant by beating two collinear lasers with frequency difference equal to the frequency of the eigenmode. Such a mode efficiently accelerates energetic electrons, executing bounce motion in the azimuthal field to high energies. At dimensionless mode plasma wave amplitude ap=ephip0/m0c2=0.55, 10 keV electrons in a plasma of density n=1017/cm3 can be accelerated to 30 MeV energy
Frontiers of particle beam physics
First, a review is given of various highly-developed techniques for particle handling which are, nevertheless, being vigorously advanced at the present time. These include soft superconductor radio frequency cavities, hard superconductor magnets, cooling rings for ions and anti-protons, and damping rings for electrons. Second, attention is focused upon novel devices for particle generation, acceleration, and focusing. These include relativistic klystrons and free electron laser power sources, binary power multipliers, photocathodes, switched-power linacs, plasma beat-wave accelerators, plasma wake-field accelerators, plasma lenses, plasma adiabatic focusers and plasma compensators. 12 refs.
Frontiers of particle beam physics
1989-11-01
First, a review is given of various highly-developed techniques for particle handling which are, nevertheless, being vigorously advanced at the present time. These include soft superconductor radio frequency cavities, hard superconductor magnets, cooling rings for ions and anti-protons, and damping rings for electrons. Second, attention is focused upon novel devices for particle generation, acceleration, and focusing. These include relativistic klystrons and free electron laser power sources, binary power multipliers, photocathodes, switched-power linacs, plasma beat-wave accelerators, plasma wake-field accelerators, plasma lenses, plasma adiabatic focusers and plasma compensators. 12 refs.
Energetic particles in the universe. How does nature beat CERN?
2009-01-01
It has been known for nearly a century that the Earth is constantly being bombarded by, to quote from the 1912 discovery paper, 'an ionizing radiation of extreme penetrating power' and extraterrestrial origin. These cosmic ray particles are now known to extend in energy right up to at least 1020 eV. This is a macroscopic amount of energy, in fact some 16 J, but all the evidence points to this being carried by ordinary atomic nuclei including protons. Such extreme events are, however, very rare and the bulk of the cosmic rays have more moderate, but still very high, energies. The theory of diffusive shock acceleration, a variant of Fermi acceleration operating at strong collisionless plasma shocks, is currently the best bet for explaining the origin of the cosmic rays. This talk will describe our current understanding of this acceleration process and the observational ...
Treatment of stable angina pectoris by ivabradine in every day practice: The REDUCTION Study
2009-01-01
Background The antianginal efficacy of ivabradine was studied in controlled clinical trials. Strict patient selection criteria may cause a discrepancy between the results of highly controlled clinical trials and everyday routine practice. The objective of this study was to evaluate the efficacy and safety of ivabradine in everyday routine practice. Methods In this multicenter study, 4,954 patients with stable angina pectoris received ivabradine in everyday routine practice and underwent follow-up for 4 months. The heart rate (HR), angina pectoris attacks, nitrate consumption, overall efficacy, and tolerance were evaluated. Results Within 4 months of treatment with ivabradine, HR was reduced by 12.4 12.2 beat/min from 82.9 15.3 to 70.4 9.2 beat/min (P P P
Regeneration of Stochastic Processes: An Inverse Method
2004-11-20
We propose a novel inverse method that utilizes a set of data to construct a simple equation that governs the stochastic process for which the data have been measured, hence enabling us to reconstruct the stochastic process. As an example, we analyze the stochasticity in the beat-to-beat fluctuations in the heart rates of healthy subjects as well as those with congestive heart failure. The inverse method provides a novel technique for distinguishing the two classes of subjects in terms of a drift and a diffusion coefficients which behave completely differently for the two classes of subjects, hence potentially providing a novel diagnostic tool for distinguishing healthy subjects from those with congestive heart failure, even at the early stages of the disease development.
2010-01-01
The present study investigated anxiety-related emotional reasoning in 9-13-year-old children using an experimental approach. Eighty-one children completed a computerized ambiguous situations test for assessing their perception of threat under two conditions. In the experimental condition, children were attached to an apparatus that allegedly recorded their heart beat, the sound of which was presented to them via headphones. In the control condition, children listened to the sound of an African djembe drum while completing the ambiguous situations test. It was found that children in the experimental condition generally provided higher threat ratings than children in the control condition, and this difference remained significant when controlling for levels of anxiety sensitivity, panic and ...
2010-01-01
Objective: This study aims to determine the failure rate of transplanted kidney grafts in recipients of organs from non-heart beating donors (NHBDs) who have had mechanical chest compressions to maintain a circulation before organ retrieval. Methods: A retrospective observational study based on review of the emergency medical service database and case histories of NHBDs, and information periodically sent by transplant units about donors and organs. The following variables were studied: age, sex, transfer hospital, time to arrival on the scene of cardiopulmonary arrest, time to arrival in hospital, number and type of organs retrieved, use of mechanical chest compression devices, and kidney function in graft recipients. The study covered the period between January 2008 and November 2009. Dur...
Students will determine the amount of blood their heart will beat in their lifetime using the provided on-line calculator. They also determine their cardiac output (blood pumped per minute) and cardiac index (blood pumped per minute per square meter of body surface area). A nomogram is provided for calculating body surface area. This lesson contains a brief activity that helps demonstrate the volume of blood pumped by your heart in one beat. Extensions in this activity explore correlations between the heart rates of different animals and their body sizes or their longevity. Included are two links to live videos titled "Heart Transplant" and "The Implantation of a Heartmate."
2011-01-01
This paper presents a new automated diagnostic system to classification of electrocardiogram (ECG) arrhythmias. The diagnostic system is executed using type-2 fuzzy c-means clustering (T2FCM) algorithm, wavelet transform (WT) and neural network. Method of combining T2FCM and WT is used to improve performance of neural network. We aimed high accuracy rate to classification of ECG beats and constituted the automated diagnostic system to improve of classifier's performance. Ten types of ECG beats selected from MIT-BIH database were used to train the system. Then, this system was tested by the ECG signals of patients. The classification accuracy of the proposed classifier, type-2 fuzzy clustering wavelet neural network (T2FCWNN), is compared with the structures formed by type-1 FCM and WT. Pro...
2010-01-01
Multidetector computed tomographic coronary angiography (CTA) image quality is inversely related to the heart rate (HR). As a result beta-blocking medication is routinely administered before investigation. In the present study, the use, contraindications, and efficacy of prescan beta blockade with regard to HR reduction and CTA image quality were assessed. In 537 patients referred for CTA, the baseline HR and blood pressure were measured on arrival, and contraindications for beta blockade were noted. Unless contraindicated, a single dose of metoprolol was administered orally 1 hour before data acquisition in patients with a HR of ≥65 beats/min according to a predefined medication protocol. After 1 hour, the HR was remeasured. A total of 283 patients (53%) had a HR of ≥65 beat...
Common marmoset embryonic stem cell can differentiate into cardiomyocytes
2008-01-01
Common marmoset monkeys have recently attracted much attention as a primate research model, and are preferred to rhesus and cynomolgus monkeys due to their small bodies, easy handling and efficient breeding. We recently reported the establishment of common marmoset embryonic stem cell (CMESC) lines that could differentiate into three germ layers. Here, we report that our CMESC can also differentiate into cardiomyocytes and investigated their characteristics. After induction, FOG-2 was expressed, followed by GATA4 and Tbx20, then Nkx2.5 and Tbx5. Spontaneous beating could be detected at days 12-15. Immunofluorescent staining and ultrastructural analyses revealed that they possessed characteristics typical of functional cardiomyocytes. They showed sinus node-like action potentials, and the beating rate was augmented by isoproterenol stimulation. The BrdU ...
Cardiac function adaptations in hibernating grizzly bears (Ursus arctos horribilis)
2010-01-01
Research on the cardiovascular physiology of hibernating mammals may provide insight into evolutionary adaptations; however, anesthesia used to handle wild animals may affect the cardiovascular parameters of interest. To overcome these potential biases, we investigated the functional cardiac phenotype of the hibernating grizzly bear (Ursus arctos horribilis) during the active, transitional and hibernating phases over a 4year period in conscious rather than anesthetized bears. The bears were captive born and serially studied from the age of 5months to 4years. Heart rate was significantly different from active (82.67.7beats/min) to hibernating states (17.82.8beats/min). There was no difference from the active to the hibernating state in diastolic and stroke volume param...
Quantitative effects of acceleration rate on fuel consumption. Technical report
1980-04-01
One factor which has a significant effect on vehicle fuel consumption is the rate at which the vehicle is accelerated. Quantitative and qualitative studies have shown that more rapid and/or more frequent accelerations result in increased fuel consumption. The EPA has conducted a study to quantify the effects of operating a vehicle at different acceleration rates. The test involved accelerating the vehicle at a constant acceleration rate to a speed of 55 mph, and maintaining the 55 mph speed until total distance traveled equaled one mile. Conceptually, this may be viewed as entering a freeway system with different acceleration rates.
Interstitial pH, K(), lactate, and phosphate determined with MSNA during exercise in humans
... in muscle sympathetic nerve activity (MSNA) and 13 /- 3 beats/min (P < 0.05) and 20 /- 2 mmHg (P < 0.05) increases in heart rate and blood pressure, respectively. During recovery, ...
Jun 9, 2010 ... Scan credits in the Image Library. ..... [Jack's peak heart rate through this period is about 120 beats ..... 120:44:10 Schmitt: (Calling dramatically, like Marley's ghost in Dickens' A Christmas Carol) I'm over here. ...
Broadband frequency mode entanglement in waveguided PDC
2008-06-13
We report the observation of beatings of the coincidence event rate in a Hong-Ou-Mandel interference (HOMI) between signal and idler photons from a parametric downconversion process inside a multi-mode KTP waveguide. As explanation we introduce bi-photonic states entangled in their broadband frequency modes and propose a suitable entanglement witness.
2005-01-01
Autonomic dysreflexia (AD) can occur during penile vibratory stimulation in men with spinal cord injury, but this is variable, and the association with lesion level is unclear. The purpose of this study was to characterize the cardiovascular responses to penile vibratory stimulation in men with spinal cord injury. We hypothesized that those with cervical injuries would demonstrate a greater degree of AD compared with men with thoracic injuries. We also questioned whether the rise in blood pressure could be attenuated by sildenafil citrate. Participants were classified as having cervical (n = 8) or thoracic (n = 5) injuries. While in a supine position, subjects were instrumented with an ECG, and arterial blood pressure was determined beat by beat. Subjects reported to the laboratory twice and received an oral dose of sildenafil citrate (25–100 mg) or no medication. Penile vibratory stimulation was performed using a handheld vibrator to the point of ejaculation. At ejaculation during the nonmedicated trials, the cervical group had a significant decrease in heart rate (–5–10 beats/min) and increase in mean arterial blood pressure (+70–90 mmHg) relative to resting conditions, whereas the thoracic group had significant increases in both heart rate (+8–15 beats/min) and mean arterial pressure (+25–30 mmHg). Sildenafil citrate had no effect on the change in heart rate or mean arterial pressure in either group. In summary, men with cervical injuries had more pronounced AD during penile vibratory stimulation than men with thoracic injuries. Administration of sildenafil citrate had no effect on heart rate or blood pressure during penile vibratory stimulation in men with spinal cord injury. Publisher: American Physiological Society Coverage: 2005-07-01T00:00:00Z
2003-02-01
Dihydropyridine Ca antagonists cause reflex tachycardia related to their hypotensive effects. Efonidipine hydrochloride has inhibitory effects on T-type Ca channels, even as it inhibits reflex tachycardia. In the present study, the influence of efonidipine hydrochloride on heart rate and autonomic nervous function was investigated. Using an electrocardiogram and a tonometric blood pressure measurement, autonomic nervous activity was evaluated using spectral analysis of heart rate/systolic blood pressure variability. Three protocols were used: a single dose of efonidipine hydrochloride was administered orally to healthy subjects with resting heart rate values of 75 beats/min or more (high-heart rate (HR) group) and to healthy subjects with resting heart rate values less than 75 beats/min (low-HR group); efonidipine hydrochloride was newly administered to untreated patients with essential hypertension, and autonomic nervous activity was investigated after a 4-week treatment period; and patients with high heart rate values ({>=}75 beats/min) who had been treated with a dihydropyridine L-type Ca channel inhibitor for 1 month or more were switched to efonidipine hydrochloride and any changes in autonomic nervous activity were investigated. In all protocols, administration of efonidipine hydrochloride decreased the heart rate in patients with a high heart rate, reduced sympathetic nervous activity, and enhanced parasympathetic nervous activity. In addition, myocardial scintigraphy with {sup 123}I-metaiodobenzylguanidine showed significant improvement in the washout rate and heart to mediastinum (H/M) ratio of patients who were switched from other dihydropyridine Ca antagonists to efonidipine hydrochloride. Efonidipine hydrochloride inhibits increases in heart rate and has effects on the autonomic nervous system. It may be useful for treating hypertension and angina pectoris, and may also have a cardiac protective function. (author)
Physics of Laser-driven plasma-based acceleration
The physics of plasma-based accelerators driven by short-pulse lasers is reviewed. This includes the laser wake-field accelerator, the plasma beat wave accelerator, the self-modulated laser wake-field accelerator, and plasma waves driven by multiple laser pulses. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse direction, electron dephasing, laser pulse energy depletion, as well as beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and plasmas with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Recent experimental results are summarized.
Physics of Laser-driven plasma-based acceleration
2003-06-30
The physics of plasma-based accelerators driven by short-pulse lasers is reviewed. This includes the laser wake-field accelerator, the plasma beat wave accelerator, the self-modulated laser wake-field accelerator, and plasma waves driven by multiple laser pulses. The properties of linear and nonlinear plasma waves are discussed, as well as electron acceleration in plasma waves. Methods for injecting and trapping plasma electrons in plasma waves are also discussed. Limits to the electron energy gain are summarized, including laser pulse direction, electron dephasing, laser pulse energy depletion, as well as beam loading limitations. The basic physics of laser pulse evolution in underdense plasmas is also reviewed. This includes the propagation, self-focusing, and guiding of laser pulses in uniform plasmas and plasmas with preformed density channels. Instabilities relevant to intense short-pulse laser-plasma interactions, such as Raman, self-modulation, and hose instabilities, are discussed. Recent experimental results are summarized.
Electron acceleration in preformed plasma channels with terawatt CO{sub 2} laser
1995-02-01
Extended cylindrical plasma channels produced under gas breakdown by axicon-focused laser beams may be used as optical waveguides in laser-driven electron accelerators. Plasma channeling of the laser beams will help to maintain a high acceleration gradient over many Rayleigh lengths. In addition, the rarefied gas density channel produced after the optical gas breakdown, and followed by a plasma column expansion, reduces multiple scattering of the electron beam. A high-power picosecond C0{sub 2}laser operational at the ATF and being further upgraded to the 1 TW level is considered as the source for a plasma channel formation and as the laser accelerator driver. We show how various laser accelerator schemes including beat wave, wake field, and Inverse Cherenkov accelerator benefit from using a channeled short-pulse C0{sub 2}laser as a driver.
2010-01-01
Reconstruction of cardiac computed tomography (CT) images is challenging when the heart rate is higher than 65 beats per minute (bpm). The optimal reconstruction time is often found to be at the end-systolic phase, but image quality remains uncertain. Using dual-source (DS) CT and 83-ms temporal resolution, we evaluated the robustness of the temporal window with low motion during the end systole. We studied 41 DSCT in consecutive patients with a heart rate
2009-01-01
SummaryBackground High cholesterol, leukocytes (LEUK) and erythrocyte sedimentation rate (ESR) are associated with cardiovascular diseases. Design Cross sectional study of 10,000 healthy young men. Methods About 10,167 men were analyzed for the association of cholesterol concentrations and erythrocyte sedimentation rate with fitness (assessed by achieved physical working capacity at a heart rate of 170 beats per min=PWC170). Physical fitness was categorized as low (2.8W/kg; n=3629). Cholesterol was categorized as elevated cholesterol (
Dynamic Responses of Marine Risers/Pipes Transporting Fluid Subject to Top End Excitations
2008-01-01
This paper deals with the dynamic responses to top end excitation of marine risers/pipes conveying internal fluid. The marine riser is often used as a flexible link between undersea bore head and subsurface offshore platform. The tidal waves and the changes of sea level consistently excite its top end connected to a floating vessel. In order to carry out the performance-based design of the marine risers, the evaluation of their dynamic responses to top end excitations is imperative. In this study, the marine riser is simulated using twodimensional beam elements. Energy functional of the marine risers conveying fluids is derived from variational principle. Nonlinear equations of motion influenced by the nonlinear Morison waveform are obtained through Hamilton’s principle. Investigation of the dynamic responses of marine risers to top end excitation is achieved using the finite element method and Newmark Average Acceleration Method. Interestingly, either beating or resonant phenomenon can be observed from the responses. It is also found that the top tension plays a major role in the increment of undamped frequencies of marine risers, while either the internal flow rate or the external hydrodynamic drag force remarkably affects the displacement amplitudes of the marine risers’ dynamic responses. Publisher: Research Online Format: application/pdf Source: Faculty of Engineering - Papers
Effect of pre operative heart rate on post spinal hypotension in obsteric patients
2010-01-01
The purpose of the study was to determine the association between of preoperative heart rate and post spinal hypotension in women undergoing cesarean section, Two hundred patients undergoing caesarean were included in the study selected on non probability convenience sampling technique, The patients were divided into two groups depending upon their pre operative heart rate. Spinal anesthesia was administered and number of patients developing hypotension was noted. Among 200 patients, who were included in the study. 112 were placed in group A and 88 were placed in group B depending on mean heart rate of 90 beats per minute or less or 91 beats per minute or more respectively. In group A 14 (11.86%) patients developed hypotension where as in group B 28 (31,82%) patients developed hypotension. Pre operative heart rate is significantly associated with post spinal hypotension in ...
Analysis of Gaussian beam and Bessel beam driven laser accelerators
1999-10-01
This paper presents a comparison of Gaussian and Bessel beam driven laser accelerators. The emphasis is on the vacuum beat wave accelerator (VBWA), employing two laser beams of differing wavelengths to impart a net acceleration to particles. Generation of Bessel beams by means of circular slits, holographic optical elements, and axicons is outlined and the image space fields are determined by making use of Huygens{close_quote} principle. Bessel beams{emdash}like Gaussian beams{emdash}experience a Guoy phase shift in the vicinity of a focal region, resulting in a phase velocity that exceeds {ital c}, the speed of light {ital in vacuo}. In the VBWA, by appropriate choice of parameters, the Guoy phases of the laser beams cancel out and the beat wave phase velocity equals {ital c}. The particle energy gain and beam quality are determined by making use of an analytical model as well as simulations. The analytical model{emdash}including the {bold v}{times}{bold B} interaction{emdash}predicts that for equal laser powers Gaussian and Bessel beams lead to identical energy gains. However, three-dimensional, finite-emittance simulations, allowing for detuning, transverse displacements, and including all the electromagnetic field components, show that the energy gain of a Gaussian beam driven VBWA exceeds that of a Bessel beam driven VBWA by a factor of 2{endash}3. The particle beam emerging from the interaction is azimuthally symmetric and collimated, with a relatively small angular divergence. A table summarizing the ratios of final energies, acceleration lengths, and gradients for a number of acceleration mechanisms is given. {copyright} {ital 1999} {ital The American Physical Society}
Electron Trapping in Self-Modulated Laser Wakefields by Raman Backscatter
1997-11-01
Simultaneous measurements of high energy electrons and plasma-wave characteristics have been conducted in a self-modulated laser-wakefield accelerator. Approximately 10{sup 8} electrons were accelerated from the background plasma to energies greater than 1MeV with a peak energy of approximately 30MeV. A strong correlation between the plasma-wave amplitude and electron production was measured with no evidence of wave breaking. Simulations indicate plasma electrons are trapped by the low-phase-velocity beat waves produced by backward Raman scattering. {copyright} {ital 1997} {ital The American Physical Society}
An optical injection scheme for a laser-plasma basedaccelerator which employs a non-collinear counter-propagating laser beamto push background electrons in the focusing and acceleration phase viaponderomotive beat with the trailing part of the wakefield driver pulseis discussed. Preliminary experiments were performed using a drive beamof a_0 = 2.6 and colliding beam of a_1 = 0.8 both focused on the middleof a 200 mu m slit jet backed with 20 bar, which provided ~; 260 mu mlong gas plume. The enhancement in the total charge by the collidingpulse was observed with sharp dependence on the delay time of thecolliding beam. Enhancement of the neutron yield was also measured, whichsuggests a generation of electrons above 10 MeV.
Acceleration of quantum algorithms using three-qubit gates
2003-10-28
Quantum-circuit optimization is essential for any practical realization of quantum computation, in order to beat decoherence. We present a scheme for implementing the final stage in the compilation of quantum circuits, i.e., for finding the actual physical realizations of the individual modules in the quantum-gate library. We find that numerical optimization can be efficiently utilized in order to generate the appropriate control-parameter sequences which produce the desired three-qubit modules within the Josephson charge-qubit model. Our work suggests ways in which one can in fact considerably reduce the number of gates required to implement a given quantum circuit, hence diminishing idle time and significantly accelerating the execution of quantum algorithms.
A randomised, simulated study assessing auscultation of heart rate at birth
2010-01-01
Background: Heart rate is a primary clinical indicator directing newborn resuscitation. The time taken to assess the heart rate by auscultation in relation to accuracy during newborn resuscitation is not known. Objective: To assess both the accuracy and time taken to assess heart rate by stethoscope in simulated resuscitation scenarios. Method: The VitalSim^(C) manikin (Laerdal Medical, Stavanger, Norway) was used in this randomised, single blind study. Four heart rate settings (0, 40, 80, 120 beats per minute (bpm)) were randomly assigned. Participants assessed them by auscultation in three different scenarios. The first scenario was to assess the actual heart rate at birth. In the second scenario, heart rate was assessed during ventilation and assigned to standard ranges (1...
BACKGROUND AND OBJECTIVES: During regional anesthesia, various stimuli leading to an adrenergic response can occur. However, simulation of an epidural test dose by using intravenous administration of epinephrine (EPI) has always been compared with an intravenous saline infusion as the control. The aim of this study was to evaluate the possibility of distinguishing in children the effect on HR by an intravascular epinephrine infusion and a painful stimulus, using heart rate variability (HRV) and beat-to-beat analysis of HR. METHODS: Thirty American Society of Anesthesiologists physical status P I children who required elective surgery were studied. At 1 minimum alveolar concentration (MAC) of sevoflurane, electrocardiogram was recorded continuously. Systolic blood pressure (SBP) was measured every minute. Measurements were performed after an intravenous administration of 0.5 microg/kg of epinephrine and during a small skin surgical incision (SI). Time-varying auto-regressive modeling of the interpolated RR sequences was performed for estimating power spectrum (msec(2)). The HF bands were defined by (0.15-0.4 Hz). RESULTS: Median (range) age and weight of all children were 3.5 (1-10) years and 16 (9-30) kg. EPI produced a lower increase in HR than did SI. SBP increased significantly more than did after SI. T-wave amplitude increased significantly after EPI but not after SI. Sixty seconds after the first change in HR, a secondary decrease (in comparison to control value) can be detected with EPI in contrast to SI. HF spectral power increased significantly after EPI administration but decreased after SI. The sensitivity, specificity, and positive and negative predictive value were respectively for DeltaHR >10 beats per minuteof 56%, 26%, 43%, and 38%; for DeltaSBP >15 mm Hg of 60%, 86%, 81%, and 67%; and for DeltaT-wave amplitude >25% of 86%, 73%, 76%, and 84%. Using detection of the secondary decrease of HR, 60 seconds after the first change in HR, sensitivity, specificity, and positive and a negative predictive value were respectively 96%, 100%, 100%, and 96%. CONCLUSIONS: Detection of the secondary HR decrease, 60 seconds after the first change in HR, allows us to distinguish the effects of a painful stimulus from those related to the epinephrine test dose at 1 MAC of sevoflurane. This secondary HR decrease induced by epinephrine appears primarily because of a compensatory increase in parasympathetic tone.
Controlled Electron Injection into Plasma Accelerators and Space Charge Estimates
2005-01-01
Plasma based accelerators are capable of producing electron sources which are ultra-compact (a few microns) and high energies (up to hundreds of MeVs) in much shorter distances than conventional accelerators. This is due to the large longitudinal electric field that can be excited without the limitation of breakdown as in RF structures.The characteristic scale length of the accelerating field is the plasma wavelength and for typical densities ranging from 1018 - 1019 cm-3, the accelerating fields and scale length can hence be on the order of 10-100GV/m and 10-40 mu m, respectively. The production of quasimonoenergetic beams was recently obtained in a regime relying on self-trapping of background plasma electrons, using a single laser pulse for wakefield generation. In this dissertation, we study the controlled injection via the beating of two lasers (the pump laser pulse ...
The response of the left ventricle to pacing-induced changes in heart rate and the atrioventricular (A-V) relation was examined with equilibrium gated radionuclide ventriculography in 20 patients who had normal ventricular function after surgery for recurrent supraventricular tachycardia. In 10 patients count-derived left ventricular ejection fraction, end-diastolic volume and stroke volume were measured during sinus rhythm and during atrial pacing at 120, 140 and 160 beats/min. In the other 10 patients similar determinations were made during sequential A-V and simultaneous ventricular and atrial (V/A) pacing, both at rates of 100 and 160 beats/min. The data indicate that the hemodynamic consequences of supraventricular tachyarrhythmias in patients with normal ventricular function are due primarily to decreases in ventricular volume as heart rate is increased and atrial contribution is lost rather than to any changes in left ventricular ejection fraction.
1981-10-01
The response of the left ventricle to pacing-induced changes in heart rate and the atrioventricular (A-V) relation was examined with equilibrium gated radionuclide ventriculography in 20 patients who had normal ventricular function after surgery for recurrent supraventricular tachycardia. In 10 patients count-derived left ventricular ejection fraction, end-diastolic volume and stroke volume were measured during sinus rhythm and during atrial pacing at 120, 140 and 160 beats/min. In the other 10 patients similar determinations were made during sequential A-V and simultaneous ventricular and atrial (V/A) pacing, both at rates of 100 and 160 beats/min. The data indicate that the hemodynamic consequences of supraventricular tachyarrhythmias in patients with normal ventricular function are due primarily to decreases in ventricular volume as heart rate is increased and atrial contribution is lost rather than to any changes in left ventricular ejection fraction.
2009-01-01
The aim of this study was to examine the physiological demands and movement patterns of female basketball players after changes in the rules of the game. Nine varsity players were studied during nine official games. Each game was videotaped to identify the frequencies of the main movements performed, heart rate was recorded continuously, and blood samples were collected to determine blood lactate concentration when the competition rules allowed. The main results showed that the players performed on average 652 ± 128 movements per game, which corresponded to a change in activity every 2.82 s. Mean heart rate was 165 ± 9 beats · min-1 (89.1% of maximum heart rate) for total time and 170 ± 8 beats · min-1 (92.5% o...
2007-01-01
The optimal combination of region-of-interest (ROI) size and strain length (SL) allowing two-segment strain and strain rate analyses in term neonates was investigated. The impact of different ROI sizes and SLs on the strain and strain rate beat-to-beat variation (BBV) was assessed in 80 good-quality tissue velocity images. Both BBVs decreased with increased ROI length and with increased SL (p < 0.05). There were no significant differences in the BBVs for ROI width 2, 3 and 4 mm (p > 0.05). Among the combinations eligible for two segment analysis, the lowest BBVs were found using SL 10 mm, ROI length 1 mm and ROI width 3 mm. Using this combination, the mean difference between the single-cycle value and two-cycle compound value for peak systolic strain rate was 6.2%, peak systo...
2010-01-01
Domestic animals are often repeatedly exposed to the same anthropogenic stressors. Based on cortisol secretion and heart rate, it has been demonstrated that transport is stressful for horses, but so far, changes in this stress response with repeated road transport have not been reported. We determined salivary cortisol concentrations, fecal cortisol metabolites, cardiac beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-naive horses (N = 8) transported 4 times over a standardized course of 200 km. Immunoreactive salivary cortisol concentrations always increased in response to transport (P < 0.001), but cortisol release decreased stepwise with each transport (P < 0.05). Concentrations of fecal cortisol metabolites increased from 55.1 ± 4.6 ng/g be...
Alternans of blood pressure and heart rate in dilated cardiomyopathy
2002-01-01
The definitive version is available at www.blackwell-synergy.comImpaired myocardial performance is known to be associated with electrical and mechanical beat-to-beat alternans phenomena. The alternans in blood pressure and heart rate and their interdependency in idiopathic dilated cardiomyopathy (IDC) were studied. The arterial blood pressure and the electrocardiograph (ECG) were continuously recorded in 22 patients suffering from IDC (age 49 ± 13 years, ejection fraction 0.33 ± 0.13, left ventricular diameter of 67 ± 8 mm) and in 21 healthy controls (age 52 ± 15 years). The beat-to-beat variations of the interbeat intervals (IBI) and of the blood pressure amplitudes (AMP) were measured. An alternans beat was defined as a beat preceded and followed by beats that had higher or lower values in the respective modality. The percentages of singular and repetitive alternans patterns, and the interdependency of the alternans patterns in AMP and IBI were assessed. The study found significantly more singular and repetitive alternans patterns in the IDC group compared to the control group both in the analysis of AMP and IBI (singular alternans in IBI: 55 ± 11 vs 47 ± 7%, P < 0.01; singular alternans in AMP: 61 ± 15 vs 45 ± 6%, P < 0.01; triple alternans in IBI: 29 ± 18 vs 16 ± 9%, P < 0.01; triple alternans in AMP: 34 ± 24 vs 12 ± 7%, P < 0.01). The amplitudes of the AMP alternans patterns were higher in IDC compared to controls (9 ± 7 vs 4 ± 2% of AMP, P = 0.01) whereas they did not differ in IBI. The correlation analysis revealed a significant interdependency of the alternans pattern in IBI and AMP in 18 of 22 IDC patients and in 12 of 21 controls (r = 0.50 ± 0.21 [IDC]; r = 0.26 ± 0.05 [controls]). The slope of the linear regression (ΔAMP vs ΔIBI) was steeper in the IDC group compared to the control group (62 ± 50 vs 20 ± 22 mmHg/s, P < 0.01). The percentages of alternans patterns appearing in IBI and AMP were positively correlated to the left ventricular diameter (r = 0.70 in the IBI, and r = 0.30 in the AMP). The blood pressure amplitude and the heart rate did not differ between the two groups. Patients suffering from IDC have a higher prevalence, stability, amplitude, and interdependency of alternans patterns in IBI and AMP compared to the control group. The amount of alternans patterns indicates the stage of disease. The alternans analysis may have impact on the functional assessment of patients suffering from heart failure.Uwe Leder, Hans-Peter Pohl, Vico Baier, Matthias Baumert, Mario Liehr, Jens Haueisen, Andreas Voss, Hans R Figulla Publisher: Futura / Blackwell Contributor: School of Electrical and Electronic Engineering Other identifier: Pacing and Clinical Electrophysiology, 2002; 25 (9):1307-1314; 0147-8389; 0020065513; 10.1046/j.1460-9592.2002.01307.x; 000178269600005 Language: en Source: http://www.blackwell-synergy.com/doi/abs/10.1046/j.1460-9592.2002.01307.x
Accuracy of clinical assessment of infant heart rate in the delivery room
2006-01-01
SummaryHeart rate (HR) dictates intervention during neonatal resuscitation. Guidelines recommend that HR be assessed by auscultation or palpation. We compared HRs determined clinically with electrocardiography (ECG) in healthy newborns in the delivery room. Clinical assessment by 23 observers randomly allocated to assess HR by one of two methods in 26 infants, was found to be inaccurate and underestimate ECG HR. The mean difference between HR assessed by auscultation and palpation ECG and HR using methodology recommended by the Neonatal Resuscitation Programme was 14 and 22 beats per minute respectively.
2010-01-01
The effects of water temperature and ammonia concentration on swimming capacity of brook charr (Salvelinus fontinalis, Mitchill, 1814) were determined by measuring gait transition speed (Ugt, cms^-^1), maximum burst speed (Umax, cms^-^1), tail-beat amplitude (a, cm), tail-beat frequency (f, Hz), maximum acceleration of bursts (Amax, cms^-^2), number of bursts, distance of bursts (cm) and total swimming distance (cm) in a 4.5m long experimental raceway with increasing upstream water velocity. Temperatures other than the acclimation temperature of 15^oC significantly reduced swimming characteristics of gait transition, i.e. Ugt and Amax, while increased ammonia concentration reduced the measures of swimming after Ugt: Umax, the relationship between f and swimming speed above Ugt, a, Amax and...
Non-stationary excitation of beams of electromagnetic waves in the beat accelerator
1995-12-31
Resonance excitation of the plasma waves by beats of two electromagnetic waves is thought to be one of the most promising ways to generate strong electric fields. Efficiency of conversion of the electromagnetic radiation into the electrostatic one is determined by nonlinear processes. In the unidimensional case the mechanisms of plasma field saturation have been considered rather thoroughly: occurrence of the multi-flow character by the motion of electrons oscillating in the wave field ({open_quotes}wavebreaking{close_quotes}), development of parametric instabilities, variation of plasma oscillation eigenfrequencies due to relativistic variation of the electron mass. These processes determine actually the {open_quotes}usable{close_quotes} pulse length or interaction length of electromagnetic waves. It is evident that the effect of self-focusing of electromagnetic waves when excited by the plasma wave may benefit generation of stronger waves at shorter pulse duration. Along with {open_quotes}energy benefits{close_quotes} one should expect noticeable expansion of the focus region that is well known at non-stationary self-focusing
1999-12-25
In the prior paper, a loop-type osmotic beat pipe was investigated on the heat transport rate from the upper position to the lower. The beat transport rate of this osmotic heat pipe, however, was very small because of small driving force for the solution circulation. Therefore, the osmotic heat pipe with the higher driving force is devised. The larger driving force is produced by a two-phase flow taking place in the solution riser. For the sake of that, a vopor-liquid separator is installed at the top of the apparatus and a heated section is attached as some distance below the separator, so that buoyant force caused by density difference between the fluids in the solution riser and downcomer increases. This osmotic heat pipe with the two-phase solution circulation loop indicates the higher heat transport rate than that of the osmotic heat pipe shown in the prior paper. (author)
2010-01-01
In this work, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550nm. The sources are based on the non-linear compression of an initial beat-signal through a multiple four-wave mixing process taking place into an optical fiber. We experimentally demonstrate real-time monitoring of a 20GHz pulse source having an integrated phase noise 0.01 radian by phase locking the initial beat note against a reference RF oscillator. Based on this technique, we also experimentally demonstrate a well-separated high-quality 110fs pulse source having a repetition rate of 2THz. Finally, we show that with only 1.4m of standard single mode fiber, we can achieve a twofold increase of the repetition rate, up to 3.4THz, throu...
In this work, we report recent progress on the design of all-fibered ultra-high repetition-rate pulse sources for telecommunication applications around 1550 nm. The sources are based on the non-linear compression of an initial beat-signal through a multiple four-wave mixing process taking place into an optical fiber. We experimentally demonstrate real-time monitoring of a 20 GHz pulse source having an integrated phase noise 0.01 radian by phase locking the initial beat note against a reference RF oscillator. Based on this technique, we also experimentally demonstrate a well-separated high-quality 110 fs pulse source having a repetition rate of 2 THz. Finally, we show that with only 1.4 m of standard single mode fiber, we can achieve a twofold increase of the repetition rate, up to 3.4 THz, through the self-imaging Talbot effect. Experimental results are supported by numerical simulations based on the generalized non-linear Schrdinger equation.
Heart rate variability (HRV) is a measure of the beat-to-beat variations in heart rate related to the work of autonomic nervous system. It may serve as a psychophysiological indicator for arousal, emotional state and stress level. We used this parameter in both the assessment and biofeedback training, for dealing with five groups of common mental health problem in school children (anxious-phobic, somatoform, obsessive-compulsive, attention deficit hyperactivity and conduct disorders). The obtained results were compared with healthy children at the same age. In order to define the four main characteristics of personality (extroversion/introversion, neuroticism/stability, psychopathological traits and honesty) Eysenck Personality Questionnaire was applied. Results showed significantly higher psychopathological traits in ADHD and somatoform group, lower extroversion in somatoform, higher neurotism in OCD and lower lie scores in ADHD and OCD groups. As HRV instrument we used Heart Math Freeze-Framer System. After 15 sessions of training, children from nearby all groups showed improved high and medium HRV which corresponded to the improved clinical outcome. Hereby, the best results were obtained for conduct and anxiety disorder, and the worst for ADHD.
Generation of strongly chaotic beats
2007-04-26
The letter proposes a procedure for generation of strongly chaotic beats that have been hardly obtainable hitherto. The beats are generated in a nonlinear optical system governing second-harmonic generation of light. The proposition is based on the concept of an optical coupler but can be easily adopted to other nonlinear systems and Chua's circuits.
Existence and stability of a beat regime with resonator frequency in a ring laser
1978-03-01
On the basis of a general qualitative analysis of quantum equations of motion describing the dynamics of a ring laser beat signal, a proof is given of the theorem of the existence and stability of the beat regime with resonator frequency.
Increased beat-to-beat R amplitude variability in patients with panic disorder
2010-01-01
In patients with panic disorder, an anxiety disorder, isoproterenol increases beat-to-beat QRS amplitude variability much more than in normal controls. In this pilot study, we found that patients with panic disorder had significantly higher beat-to-beat QRS amplitude variability compared to controls in resting supine and standing postures. This may be partly due to myocardial electrical instability or irregular respiration in this patient group. These findings are important in view of the association between panic disorder and increased cardiovascular mortality.
All-optical beamlet train generation
2003-05-12
One of the critical issues for the development of Laser Wake Field Acceleration (LWFA), which has the promise of creating table-top, GeV accelerators, is the loading of beamlets into the accelerating buckets. All optical injection schemes, which include LILAC, beat-wave colliding pulse injection, wave breaking injection, and phase-kick injection, provide a technique for doing so. Although a single bunch can have desirable properties such as energy spread of the order of a few percent, femtosecond duration k and low emittance (<1 mm-mrad), recent simulations show that such methods lead to efficiencies of transfer of plasma wave energy to beam energy that are low compared with conventional RF accelerators when only a single pulse is generated. Our latest simulations show that one can improve on this situation through the generation of a beamlet train. This can occur naturally through phase-kick injection at the front of the train and transverse wave breaking for the trailing pulses. The result is an efficiency improvement of the order of the number of beamlets in the train.
Theoretical Limits on Errors and Acquisition Rates in Localizing Switchable Fluorophores
2008-09-25
A variety of recent imaging techniques are able to beat the diffraction limit in fluorescence microcopy by activating and localizing subsets of the fluorescent molecules in the specimen, and repeating this process until all of the molecules have been imaged. In these techniques there is a tradeoff between speed (activating more molecules per imaging cycle) and error rates (activating more molecules risks producing overlapping images that hide information on molecular positions), and so intelligent image-processing approaches are needed to identify and reject overlapping images. We introduce here a formalism for defining error rates, derive a general relationship between error rates, image acquisition rates, and the performance characteristics of the image processing algorithms, and show that there is a minimum acquisition time irrespective of algorithm performance. We also consider algorithms that can infer molecular positions from images of overlapping blurs, and derive the dependence of the minimimum acquisition time on algorithm performance.
Numerical model for plasma electron acceleration in laser wakefield accelerators
1997-12-31
Plasma wakefields produced by a sub-picosecond, high intensity laser pulse in a dense gas jet can accelerate plasma electrons to high energies. The acceleration is believed to be a two stage process in which plasma electrons are accelerated to moderate energies by a low phase velocity wave and then trapped and accelerated by the high phase velocity (v{sub p} {approximately} c), large amplitude wakefield. The laser wakefield accelerator (LFWA) experiment at the Naval Research Laboratory has produced up to 30 MeV electrons with no external injector when operating in the self-modulated regime. The low phase velocity wave in this case could arise from the beating of the laser pump pulse with a wave arising from the backward Raman instability. This interpretation is supported by a numerical model which follows the motion of plasma electrons in analytically-prescribed fields corresponding to the laser pump pulse, the forward-going wakefield, and the Raman waves. The accelerated electrons have a large energy spread and are trapped in several bunches. Esarey, et al. have proposed a scheme which would operate in the standard LWFA regime and employs three collinear laser pulses: the large amplitude pump pulse, a lower amplitude follower pulse at the same frequency, and a counterstreaming colliding pulse at a slightly lower frequency. The interaction between the follower pulse and the colliding pulse produces the first stage of acceleration. The numerical model predicts that if the delay between the pump and follower pulses is optimized, a single short pulse bunch of accelerated plasma electrons with {approximately} 20--30% energy spread can be produced. Even if there is no guiding of the laser pulse, the model predicts that the beam energy can be tens of MeV with a bunch length of tens of femtoseconds.
Plasma based charged-particle accelerators
2004-01-01
Studies of charged-particle acceleration processes remain one of the most important areas of research in laboratory, space and astrophysical plasmas. In this paper, we present the underlying physics and the present status of high gradient and high energy plasma accelerators. We will focus on the acceleration of charged particles to relativistic energies by plasma waves that are created by intense laser and particle beams. The generation of relativistic plasma waves by intense lasers or electron beams in plasmas is important in the quest for producing ultra-high acceleration gradients for accelerators. With the development of compact short pulse high brightness lasers and electron positron beams, new areas of studies for laser/particle beam-matter interactions is opening up. A number of methods are being pursued vigorously to achieve ultra-high acceleration gradients. These include the plasma beat wave accelerator mechanism, which uses conventional long pulse ({approx}100 ps) modest intensity lasers (I {approx} 10{sup 14}-10{sup 16} W cm{sup -2}), the laser wakefield accelerator (LWFA), which uses the new breed of compact high brightness lasers (<1 ps) and intensities >10{sup 18} W cm{sup -2}, the self-modulated LWFA concept, which combines elements of stimulated Raman forward scattering, and electron acceleration by nonlinear plasma waves excited by relativistic electron and positron bunches. In the ultra-high intensity regime, laser/particle beam-plasma interactions are highly nonlinear and relativistic, leading to new phenomena such as the plasma wakefield excitation for particle acceleration, relativistic self-focusing and guiding of laser beams, high-harmonic generation, acceleration of electrons, positrons, protons and photons. Fields greater than 1 GV cm{sup -1} have been generated with particles being accelerated to 200 MeV over a distance of millimetre. Plasma wakefields driven by positron beams at the Stanford Linear Accelerator Center facility have accelerated the tail of the positron beam. In the near future, laser plasma accelerators will be producing GeV particles. (topical review)
Third-Degree AV Block from Extended-Release Diltiazem Ingestion in a Nine-Month-Old
2010-01-01
Calcium channel blocker (CCB) overdose is associated with dysrhythmias and atrioventricular (AV) block, however, experience with infant CCB overdose is limited. A 9-month-old girl was found playing with tablets of extended-release diltiazem 120 mg. The patient had two episodes of emesis, which contained pill fragments, and was brought to the Emergency Department (ED) 4.5 h after being found. Vital signs were: rectal temperature 37.1°C, pulse 87 beats/min, respiratory rate 30–40 breaths/min, blood pressure 72/48 mm Hg, and oxygen saturation (SpO2) 99% on room air. Otherwise, the patient was well-appearing, with normal skin color and examination. The electrocardiogram revealed third-degree atrioventricular block with a ventricular rate of 90 beats/min, QRS 68 ms, and QTc 411 ms...
Impairment of cardiac autonomic control in patients with amyotrophic lateral sclerosis
2010-01-01
Abstract The aim of this study was to investigate autonomic cardiac control in patients with amyotrophic lateral sclerosis (ALS). Fifty-five patients with sporadic ALS (28 female and 27 male; average age 56.00 +- 10.34 years) were compared to 30 healthy controls (17 female and 13 male; average age 42.87 +- 11.91 years). Patients with previous history of cardiac disease, diabetes mellitus, and impaired respiratory function were excluded from the study. Cardiovascular autonomic tests according to Ewing, power spectrum analysis of RR variability (low- and high-frequency bands - LF and HF, LF/HF index), real-time beat-to-beat ECG signal monitoring with heart rate variability analysis and baroreflex function analysis were carried out in all patients. Time-domain parameters of heart rate variabi...
2006-05-11
The statistical properties of heart beat intervals of 130 long-term surface electrocardiogram recordings during atrial fibrillation (AF) are investigated. We find that the distribution of interbeat intervals exhibits a characteristic exponential tail, which is absent during sinus rhythm, as tested in a corresponding control study with 72 healthy persons. The rate of the exponential decay lies in the range 3-12 Hz and shows diurnal variations. It equals, up to statistical uncertainties, the level of the previously uncovered white noise part in the power spectrum, which is also characteristic for AF. The overall statistical features can be described by decomposing the intervals into two statistically independent times, where the first one is associated with a correlated process with 1/f noise characteristics, while the second one belongs to an uncorrelated process and is responsible for the exponential tail. It is suggested to use the rate of the exponential decay as a further parameter for a better classification of AF and for the medical diagnosis. The relevance of the findings with respect to a general understanding of AF is pointed out.
2010-01-01
This study examined the effect of aerobic exercise training on vagal and sympathetic influences on the modulations of heart rate and systolic blood pressure in response to an oral glucose load in obese individuals with and without type 2 diabetes mellitus (T2D). Beat-to-beat arterial pressure and continuous electrocardiogram were measured after a 12-hour overnight fast and in response to glucose ingestion (75 g dextrose) in obese subjects with (T2D group, n = 23) and without (OB group, n = 36) T2D before and after 16 weeks of aerobic exercise training at moderate intensity. Autonomic modulation was assessed using spectral analysis of systolic blood pressure variability (BPV), heart rate variability (HRV), and analysis of baroreflex sensitivity (BRS). Glucose ingestion significantly increas...
Dynamic characteristics of heart rate control by the autonomic nervous system in rats
2010-01-01
We estimated the transfer function of autonomic heart rate (HR) control by using random binary sympathetic or vagal nerve stimulation in anaesthetized rats. The transfer function from sympathetic stimulation to HR response approximated a second-order, low-pass filter with a lag time (gain, 4.29 +- 1.55 beats min-1 Hz-1; natural frequency, 0.07 +- 0.03 Hz; damping coefficient, 1.96 +- 0.64; and lag time, 0.73 +- 0.12 s). The transfer function from vagal stimulation to HR response approximated a first-order, low-pass filter with a lag time (gain, 8.84 +- 4.51 beats min-1 Hz-1; corner frequency, 0.12 +- 0.06 Hz; and lag time, 0.12 +- 0.08 s). These results suggest that the dynamic characteristics of HR control by the autonomic nervous system in rats are similar to those of larger mammals.
Coimbra University Hospitals’ Bone and Tissue Bank: Twenty-two Years of Experience
2005-01-01
We report the microbiological contamination rate of sterilely procured 3953 tissue allografts obtained during 22 years of activity for musculoskeletal reconstruction from 1982 to 2003. From 1987 to 2000, allograft retrievals were performed in 191 cadaveric donors and in 323 living donors. In the former group 30 retrievals (15.7%) were excluded based on laboratory criteria. Among living donors 108 femoral heads (33.4%) were also excluded by the same criteria. The microbiological contamination rate of sterilely procured allografts in the operating room was 8.3% for cadaveric donors and 18.2% for living donors. A questionable positive serology for HIV antigen was registered in two non–heart-beating donors. Hepatitis C virus antibodies were positive in two other non–heart-beating...
2006-03-16
We describe a method for analyzing the stochasticity in the non-stationary data for the beat-to-beat fluctuations in the heart rates of healthy subjects, as well as those with congestive heart failure. The method analyzes the returns time series of the data as a Markov process, and computes the Markov time scale, i.e., the time scale over which the data are a Markov process. We also construct an effective stochastic continuum equation for the return series. We show that the drift and diffusion coefficients, as well as the amplitude of the returns time series for healthy subjects are distinct from those with CHF. Thus, the method may potentially provide a diagnostic tool for distinguishing healthy subjects from those with congestive heart failure, as it can distinguish small differences between the data for the two classes of subjects in terms of well-defined and physically-motivated quantities.
Traverse to Station 1 - NASA - Welcome to NASA Headquarters
Jun 10, 2010 ... 121:29:53 Parker: Jack, you might give us a frame count on Hotel. 121:30:00 Schmitt: Okay, Bob. 121:30:03 Parker: And we're going to hand over stations. ... 121:30:47 Cernan: Let me turn around then. I got to get on your. .... at the end of this run, his heart rate will peak at 130 beats per minute. ...
New limit on signals of Lorentz violation in electrodynamics
2003-01-01
We describe the results of an experiment to test for spacetime anisotropy terms that might exist from Lorentz violations. The apparatus consists of a pair of cylindrical superconducting cavity-stabilized oscillators operating in the TM010 mode with one axis east-west and the other vertical. Spatial anisotropy is detected by monitoring the beat frequency at the sidereal rate and its first harmonic. We see no anisotropy to a part in 1013. This puts a comparable bound on four linear combinations of parameters in the general standard model extension, and a weaker bound of -9 on three others
Decoy state quantum key distribution with modified coherent state
To beat photon-number splitting attack, decoy state quantum key distribution (QKD) based on the coherent state has been studied widely. We present a decoy state QKD protocol with a modified coherent state (MCS). By destructive quantum interference, a MCS with fewer multiphoton events can be obtained, which may improve the key bit rate and security distance of QKD. Through numerical simulation, we show about a 2-dB increment on the security distance for Bennett-Brassard (1984) protocol.
A New Limit on Signals of Lorentz Violation in Electrodynamics
We describe the results of an experiment to test for spacetime anisotropy terms that might exist from Lorentz violations. The apparatus consists of a pair of cylindrical superconducting cavity-stabilized oscillators operating in the TM_{010} mode with one axis east-west and the other vertical. Spatial anisotropy is detected by monitoring the beat frequency at the sidereal rate and its first harmonic. We see no anisotropy to a part in 10^{13}. This puts a comparable bound on four linear combinations of parameters in the general Standard Model extension, and a weaker bound of <4 x 10^{-9} on three others.
The Interplanetary Overlay Networking Protocol Accelerator
A document describes the Interplanetary Overlay Networking Protocol Accelerator (IONAC) an electronic apparatus, now under development, for relaying data at high rates in spacecraft and interplanetary radio-communication ...
A rollercoaster lesson. Students learn to calculate the speed, velocity, acceleration, and inertia of a moving object and distinguish between distance and displacement. They also calculate the acceleration rates of the nation's fastest roller coasters.
1991-01-01
Changes in the pattern of the global left ventricular (LV) time-activity curve with increasing pacing rates were evaluated using radionuclide ventriculography in 15 patients with chronically implanted right ventricular VVI pacemakers. The variables obtained were correlated with the conventional systolic time intervals recorded immediately after radionuclide ventriculography in 8 of the 15 patients. Increasing the pacing rate from 50 to 110 beats per minute (bpm) altered the pattern and timing of LV contraction and filling dramatically. It produced progressive delay and reduction of LV contraction, thus shortening the LV diastolic filling time, and sometimes resulting in LV filling even during early systole. Despite these profound alterations, relative cardiac output increased progressively, peaking at a pacing rate of 110 bpm in most patients. In paced patients, ...
Theory and simulations of novel plasma-based accelerators and light sources
1989-01-01
The authors begins by introducing both the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wakefield Accelerator (PWFA). After these two methods of producing relativistic electron plasma waves have been introduced, he begins his study of certain key accelerator issues relevant to plasma-based accelerators. Analytic results for important quantities of interest, such as maximum beam loading current, efficiency, and energy spread that can be obtained from plasma accelerators will be given. These results will be compared with one- and two-dimensional particle-in-cell (PIC) computer simulations. He then introduces a new method of frequency upshifting short pulses of electromagnetic radiation, which makes use of relativistic plasma waves. This novel method makes use of a fact first noted in chapter 2; namely, that the response of a plasma to a either a short laser pulse or a relativistic electron beam is nearly identical. Thus the laser pulse can be represented by a negatively charged macroparticle in the plasma. By analogy, he shows that since it is possible to accelerate a charged macroparticle in a plasma wave, acceleration of the laser pulse is also possible. This acceleration is equivalent to upshifting the frequency of the laser. The effects of quickly creating a plasma around a monochromatic electro-magnetic source wave, on time-scales on the order of a cycle of the wave, is then investigated. It is found that this results in an upshifting of the wave frequency, which can be varied by changing the plasma density. It is also found that a substantial fraction of the B-field associated with the initial wave can be frozen in the plasma as a time independent B-field.
Shear flow induced wave couplings in the solar wind
A sheared background flow in a plasma induces coupling between different MHD wave modes, resulting in their mutual transformations with corresponding energy redistributing between the modes. In this way, the energy can be transfered from one wave mode to the other, but energy can also be added to or extracted from the background flow. In the present paper it is investigated whether the wave coupling and energy transfer mechanisms can operate under solar wind conditions. It is shown that this is indeed the case. Hence, the long-period waves observed in the solar wind at r > 0.3 AU might be generated by much faster periodic oscillations in the photosphere of the Sun. Other possible consequences for observable beat phenomena in the wind and the acceleration of the solar wind particles are also discussed.
Backward Compton scattering for probing electric fields in a plasma
A new method is suggested for probing ultrahigh electric fields associated with relativistic plasma waves in high-density plasmas. A relativistic electron beam and an intense photon beam are collided inside the plasma. In the absence of any perturbing fields, the electrons Compton scatter some of the photons. In the backward direction, the frequency of the scattered radiation is roughly 4..gamma../sup 2/..omega../sub 0/ with a frequency spread of --2(..delta gamma../..gamma..). When strong electric fields are present, some of the electrons are accelerated and others are decelerated. This leads to broadening of the Compton-scattered spectrum. An experiment designed to probe coherent longitudinal electric fields of a beat-excited plasma wave will be described. This technique has the potential to give time-resolved information about relativistic wave particle interaction.
Backward Compton scattering for probing electric fields in a plasma
1986-08-01
A new method is suggested for probing ultrahigh electric fields associated with relativistic plasma waves in high-density plasmas. A relativistic electron beam and an intense photon beam are collided inside the plasma. In the absence of any perturbing fields, the electrons Compton scatter some of the photons. In the backward direction, the frequency of the scattered radiation is roughly 4..gamma../sup 2/..omega../sub 0/ with a frequency spread of --2(..delta gamma../..gamma..). When strong electric fields are present, some of the electrons are accelerated and others are decelerated. This leads to broadening of the Compton-scattered spectrum. An experiment designed to probe coherent longitudinal electric fields of a beat-excited plasma wave will be described. This technique has the potential to give time-resolved information about relativistic wave particle interaction.
2009-01-01
A paucity of empirical research exists into surf lifesaving competition from which coaches and athletes may formulate training and recovery strategies. Seventeen (male = 9; female = 8) high-performance surf lifesavers (21.2±3.9 years) contested multiple rounds of team and individual events at a 2-day surf lifesaving competition. Individual events consisted of the multi-discipline ironman (IRON), paddle board (BOARD) and surf swim (SWIM). Blood lactate (BLa), rating of perceived exertion (RPE) and heart rate (HR) were determined following heats, semi-finals and final. IRON HR and RPE following semi-finals (153.0±21.6 beats min−1 and 14.4±1.5) and final (171.0±9.1 beats min−1 and 19.1±0.2) were greater than heats (141.8±17.2 beats min−1 and 12.0±1.9; p < 0.05) and final BLa (10.5±2.8 mmol L−1) was greater than heats (5.8±3.6 mmol L−1; p < 0.05). BOARD BLa and HR were greater after the final (9.0±2.8 mmol L−1 and 159.0±19.9 beats min−1) compared to heats (4.7±2.4 mmol L−1 and 133.0±17.1 beats min−1; p < 0.05). No significant differences were identified for SWIM. RPE—HR relationships were identified for pooled IRON and BOARD results following semi-finals (0.668; p < 0.05) and finals (r = 0.741; p < 0.05). In conclusion, high-performance surf lifesavers employ race strategies with all-out maximal exercise limited to semi-finals and finals. Publisher: Elsevier Format: application/pdf Other identifier: Sinclair, Wade H., Kerr, Rebecca M., Spinks, Warwick L., and Leicht, Anthony S. (2009) Blood lactate, heart rate and rating of perceived exertion responses of elite surf-lifesavers to high-performance competition. Journal of Science and Medicine in Sport, 12 (1). pp. 101-106. ISSN 1440-2440
Inertial confinement fusion and related results
1998-12-31
The basic laser plasma interaction processes are studied, which include the development of the nonlinear force of ponderomotion where the revealing discovery of the few-picosecond stochastic pulsation as measured by Maddever and Luther-Davies is recognised as the main source of negativity in laser plasma interaction, contrary to parametric effects. This can be explained by ripples generating the Laue-Bragg lattices known since 1974. The evaluation with our genuine two fluid hydro-code reproduced the experiments and shows how smoothing techniques eliminate the pulsation. This result proves that direct driver laser fusion with very low reflectivity and high-energy input into the plasma for ICF compression is an available solution for laser fusion. This is also applicable for the use of longer wavelengths (eg. the fundamental wavelength of neodymium glass lasers) with 3 times higher pulse energy than with third harmonics being constructed with the multi-megajoule lasers. Further fundamental studies about the initial ionisation and subsequent acceleration process of the emitted electrons by the nonlinear (ponderomotive) forces was initiated in 1979 and are now under worldwide studies, eg. the correspondence principle of electromagnetic interaction. A further field of work is devoted to the acceleration of electrons by lasers in vacuum (contrary to plasma mechanisms as the beat wave or wake field process) leading to very high energy and large numbers of accelerated electrons
1991-06-01
The relationship between myocardial ischemia detected by exercise thallium-201 scintigraphy and repetitive ventricular premature beats (VPBs) during ambulatory monitoring was evaluated in 57 patients with recent myocardial infarction. Multivariate analysis was performed to obtain the relatively important factor related to repetitive VPBs with the use of the following variables: age, redistribution, left ventricular ejection fraction, serum potassium and magnesium concentration, QRS score, left ventricular aneurysm, and the number of diseased vessels. Thirty-five patients had redistribution, but only three of them had repetitive VPBs during exercise testing. The average heart rate before 79% of 398 episodes of repetitive VPBs during ambulatory monitoring was in the range of 56 to 70/min. These data indicate that most of repetitive VPBs during ambulatory monitoring were not provoked by exercise-induced acute myocardial ischemia. However, redistribution was found to be an important factor associated with repetitive VPBs. The electrical abnormality relating to a substrate characterized by chronic reversible ischemia may explain the association between redistribution and repetitive VPBs.
2009-01-01
The mammalian heart expresses at least five phosphodiesterases (PDE15). Catecholamines produce surges of inotropically relevant cAMP through 1-adrenoceptor stimulation. cAMP is mainly hydrolysed by PDE3 and/or PDE4 thereby blunting contractility. Basal sinoatrial beating rate in mouse, rat, piglet and rabbit sinoatrial cells is reduced by PDE3 and/or PDE4 through hydrolysis of cAMP. However, in rodents, the tachycardia elicited by catecholamines through production of cAMP by -adrenoceptor activation is not controlled by PDE3 and PDE4, despite a blunting effect of PDE3 or/and PDE4 on basal sinoatrial beating, but it is unknown whether PDE3 limits catecholamine-evoked tachycardia in the rabbit. Since rabbit sinoatrial cells are an important model for pacemaker research, we investigate...
Influence of cold water face immersion on post-exercise parasympathetic reactivation
2010-01-01
The aim of the present study was to investigate the effect of cold water face immersion on post-exercise parasympathetic reactivation, inferred from heart rate (HR) recovery (HRR) and HR variability (HRV) indices. Thirteen men performed, on two different occasions, an intermittent exercise (i.e., an all-out 30-s Wingate test followed by a 5-min run at 45% of the speed reached at the end of the 3015 Intermittent Fitness test, interspersed with 5min of seated recovery), randomly followed by 5min of passive (seated) recovery with either cold water face immersion (CWFI) or control (CON). HR was recorded beat-to-beat and vagal-related HRV indices (i.e., natural logarithm of the high-frequency band, LnHF, and natural logarithm of the square root of the mean sum of squared differences betw...
2009-03-01
Full Text Available.The mechanisms underlying sudden cardiac death (SCD) are complex and diverse. Therefore, correct application of any marker to risk stratify patients for appropriate therapy requires knowledge regarding how the marker is reflective of a particular electro-anatomical substrate for arrhythmias. Non-invasive measurement of beat-to-beat alternation of the electrocardiographic T-wave, referred to as T-wave alternans (TWA), is an important marker of risk for sudden cardiac death (SCD). Is this relationship a mere association or is TWA mechanistically linked to SCD? Recent experimental evidence strongly supports a mechanistic relationship between TWA and SCD. This review will consider the underlying mechanisms of TWA derived from experimental studies, as they relate to clinical observations of TWA in humans, addressing the following questions derived from common clinical observations: 1) Where does TWA on the surface ECG come from? 2) Why is controlled heart rate elevation required to elicit TWA? 3) Why is TWA associated with risk for SCD? 4) Why is TWA associated with a broad range of ventricular arrhythmias? and 5) How do commonly used medications affect TWA?
The behaviours of juvenile Chinook salmon Oncorhynchus tshawytscha were evaluated during a temperature increase from 8.8 to 23.2C, which was designed to simulate unique thermal conditions present in a hydroelectric reservoir. The percent of fish with an active swimming behaviour increased from 26 to 93 % and mean opercular beat rates increased from 76 to 159 beats per minute between basal and maximum temperatures. Fish equilibrium did not change significantly throughout the experiment and relatively little mortality (12 %) occurred. Thermal stress is likely incurred by juvenile salmon experiencing a temperature change of this magnitude; however, stress induced in this study was primarily sublethal. Behavioural changes accompanying thermal stress (e.g., erratic swimming) may increase predation potential in the wild despite being sublethal during laboratory experiments.
Quantum beats of polarization of light induced by anisotropic collisions
1989-04-01
It is shown that anisotropic collisions of excited atoms with the particles exciting them are accompanied by the onset of quantum beats of polarization whose frequency and decay constant are proportional to the number of collisons (to the flux density of the perturbing particles). The onset of such beats is based on the interconversion of the alignment and orientation of the angular momenta of the atoms under anisotropic collision conditions. Estimates of the frequencies and decay constants of the quantum beats of polarization are given.
PROCEDURES AND ACCURACY ESTIMATES FOR BETA-BEAT CORRECTION IN THE LHC.
2006-06-26
The LHC aperture imposes a tight tolerance of 20% on the maximum acceptable beta-beat in the machine. An accurate knowledge of the transfer functions for the individually powered insertion quadrupoles and techniques to compensate beta-beat are key prerequisites for successful operation with high intensity beams. They perform realistic simulations to identify quadrupole errors in LHC and explore possible ways of correction to minimize beta-beat below the 20% level.
Longitudinal mode beat intensities in a cw HF chemical laser
Longitudinal mode beat intensities in a free-running cw HF chemical laser have been investigated. A simple expression was derived that describes the variation of beat intensity with tuning frequency. Experimental observations of the variation of beat intensity with tuning frequency in a HF chemical laser agree with the theoretical prediction. (AIP)
Longitudinal mode beat intensities in a cw HF chemical laser
1976-09-15
Longitudinal mode beat intensities in a free-running cw HF chemical laser have been investigated. A simple expression was derived that describes the variation of beat intensity with tuning frequency. Experimental observations of the variation of beat intensity with tuning frequency in a HF chemical laser agree with the theoretical prediction. (AIP)
Hyperchaotic beats and their collapse to the quasiperiodic oscillations
2008-01-01
The letter shows the possibility of generation of hyperchaotic beats characterized by four, three or two positive Lyapunov exponents. The beats are a result of linear coupling of two identical nonlinear subsystems describing second-harmonic generation of light (SHG). The rapid transition from highly chaotic beats to quasiperiodic oscillations is studied.
Gain enhancement plasma-loaded FEL in the presence of beat waves
1995-12-31
An expression for the dielectric permittivity of underdense plasma interacting with laser beat waves is derived. It is shown that the presence of beat waves in plasma results in an effective growth of the plasma frequency. The FEL Gain is investigated in the case when the frequency of soft photons weakly depending on the electron beam energy and the synchronism condition is maintained. It is shown that the plasma beat waves lead to the essential increase in FEL gain.
We investigate quantum teleportation through dissipative channels and calculate teleportation fidelity as a function of damping rates. It is found that the average fidelity of teleportation and the range of states to be teleported depend on the type and rate of the damping in the channel. Using the fully entangled fraction, we derive two bounds on the damping rates of the channels: one is to beat the classical limit and the second is to guarantee the nonexistence of any other copy with better fidelity. The effect of the initially distributed maximally entangled state on the process is presented; the concurrence and the fully entangled fraction of the shared states are discussed. We intend to show that prior information on the dissipative channel and the range of qubit states to be teleported is helpful for the evaluation of the success of teleportation, where success is defined as surpassing the fidelity limit imposed by the fidelity of the 1-to-2 optimal cloning machine for the specific range of qubits.
2007-09-12
We investigate quantum teleportation through dissipative channels and calculate teleportation fidelity as a function of damping rates. It is found that the average fidelity of teleportation and the range of states to be teleported depend on the type and rate of the damping in the channel. Using the fully entangled fraction, we derive two bounds on the damping rates of the channels: one is to beat the classical limit and the second is to guarantee the non-existence of any other copy with better fidelity. Effect of the initially distributed maximally entangled state on the process is presented; and the concurrence and the fully entangled fraction of the shared states are discussed. We intend to show that prior information on the dissipative channel and the range of qubit states to be teleported is helpful for the evaluation of the success of teleportation, where success is defined as surpassing the fidelity limit imposed by the fidelity of 1-to-2 optimal cloning machine for the specific range of qubits.
Rates of Processes with Coherent Production of Different Particles and the GSI Time Anomaly
2008-05-06
With the help of an analogy with a double-slit experiment, it is shown that the standard method of calculation of the rate of an interaction process by adding the rates of production of all the allowed final states, regardless of a possible coherence among them, is correct. It is a consequence of causality. The claims that the GSI time anomaly is due to the mixing of neutrinos in the final state of the electron-capture process are refuted. It is shown that the GSI time anomaly may be due to quantum beats due to the existence of two coherent energy levels of the decaying ion with an extremely small energy splitting (about 10^{-15} eV) and relative probabilities having a ratio of about 1/99.
Pain in the chest in a user of cocaine
A 21-year-old man presented with pleuritic substernal chest pain of one hour's duration. The pain was exacerbated in a supine position and did not radiate. Questioning revealed that he was a recreational user of cocaine and had inhaled free-based cocaine via a pipe the previous evening and as recently as two hours before admission to the hospital. Physical examination demonstrated an anxious young man with a respiratory rate of 26 breaths per minute and shallow. He was afebrile with normal heart rate and blood pressure. His sternum was tender to palpation, and auscultation revealed precordial crepitus synchronous with systole. His electrocardiogram showed sinus rhythm at a rate of 62 beats per minute. Posteroanterior and lateral roentgenograms of the chest were obtained. A diagnosis of spontaneous pneumomediastinum was made.
Pain in the chest in a user of cocaine
1987-10-16
A 21-year-old man presented with pleuritic substernal chest pain of one hour's duration. The pain was exacerbated in a supine position and did not radiate. Questioning revealed that he was a recreational user of cocaine and had inhaled free-based cocaine via a pipe the previous evening and as recently as two hours before admission to the hospital. Physical examination demonstrated an anxious young man with a respiratory rate of 26 breaths per minute and shallow. He was afebrile with normal heart rate and blood pressure. His sternum was tender to palpation, and auscultation revealed precordial crepitus synchronous with systole. His electrocardiogram showed sinus rhythm at a rate of 62 beats per minute. Posteroanterior and lateral roentgenograms of the chest were obtained. A diagnosis of spontaneous pneumomediastinum was made.
Pain in the chest in a user of cocaine
1987-01-01
A 21-year-old man presented with pleuritic substernal chest pain of one hour's duration. The pain was exacerbated in a supine position and did not radiate. Questioning revealed that he was a recreational user of cocaine and had inhaled free-based cocaine via a pipe the previous evening and as recently as two hours before admission to the hospital. Physical examination demonstrated an anxious young man with a respiratory rate of 26 breaths per minute and shallow. He was afebrile with normal heart rate and blood pressure. His sternum was tender to palpation, and auscultation revealed precordial crepitus synchronous with systole. His electrocardiogram showed sinus rhythm at a rate of 62 beats per minute. Posteroanterior and lateral roentgenograms of the chest were obtained. A diagnosis of spontaneous pneumomediastinum was made
Muscular waves contribute to gliding rate in the freshwater gastropod Lymnaea stagnalis
2010-01-01
This study revises the mechanisms of ciliary locomotion and demonstrates muscular contribution to locomotion rate in Lymnaea stagnalis. L. stagnalis sticks to the substratum by the foot sole and moves smoothly with no visible contractions of the foot. A ciliated epithelium covering the sole is underlain by smooth muscle cells containing giant mitochondria. It is shown here that slow (basal) locomotor activity (measured as the flow rate of physiological saline over isolated sole) appears spontaneously or is induced by 108107M 5-HT. 5-HT (107104M) facilitates locomotor activity dose-dependently, and KCN (an inhibitor of mitochondrial respiration) decreases these effects to the basal level. 5-HT and KCN have no effect on the frequency of ciliary beat (stroboscopic measur...
Ivabradine and outcomes in chronic heart failure (SHIFT): a randomised placebo-controlled study
2010-01-01
Summary Background Chronic heart failure is associated with high mortality and morbidity. Raised resting heart rate is a risk factor for adverse outcomes. We aimed to assess the effect of heart-rate reduction by the selective sinus-node inhibitor ivabradine on outcomes in heart failure. Methods Patients were eligible for participation in this randomised, double-blind, placebo-controlled, parallel-group study if they had symptomatic heart failure and a left-ventricular ejection fraction of 35% or lower, were in sinus rhythm with heart rate 70 beats per min or higher, had been admitted to hospital for heart failure within the previous year, and were on stable background treatment including a b blocker if tolerated. Patients were randomly assigned by computer-generated allocation schedule to ...
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