Properties of Stalk-‘Muscle’ Contractions of Carchesium SP

1973 ◽  
Vol 58 (2) ◽  
pp. 463-471 ◽  
Author(s):  
M. RAHAT ◽  
Y. PRI-PAZ ◽  
I. PARNAS
Keyword(s):  
Relaxation Time ◽  
Decay Time ◽  
Rise Time ◽  
Muscle Contractions ◽  
Partial Summation ◽  
Contractile System ◽  
One To One ◽  
Electrical Stimuli

1. The stalk of Carchesium was found to contract in an ‘all or none’ fashion in response to electrical stimuli. Rise time and half-decay time of contractions were 40-60 msec and 800-900 msec respectively. 2. Forces developed during contraction were between 400-800 g/cm2. 3. At 0.2 stimuli/sec or less, the stalk contracted at a one-to-one ratio. At higher rates of stimuli the stalk contracted at its own pace, indicating an intrinsic refractory system. 4. No tetanic responses or summation were observed in normal stalks. In fatigued stalks, partial summation was obtained and relaxation time was increased. 5. It is concluded that the contractile system of Carchesium is probably different from that of a metazoan muscle.

Shortening of muscle relaxation time after creatine loading

1999 ◽  
Vol 86 (3) ◽  
pp. 840-844 ◽  
Author(s):  
M. van Leemputte ◽  
K. Vandenberghe ◽  
P. Hespel
Keyword(s):  
Relaxation Time ◽  
Muscle Relaxation ◽  
Muscle Contractions ◽  
Contraction Time ◽  
Healthy Male ◽  
Healthy Male Volunteers ◽  
Torque Generation ◽  
Isometric Torque ◽  
The Mean ◽  
Isometric Muscle

The effect of creatine (Cr) supplementation on muscle isometric torque generation and relaxation was investigated in healthy male volunteers. Maximal torque (Tmax), contraction time (CT) from 0.25 to 0.75 of Tmax, and relaxation time (RT) from 0.75 to 0.25 of Tmax were measured during 12 maximal isometric 3-s elbow flexions interspersed by 10-s rest intervals. Between the pretest and the posttest, subjects ingested Cr monohydrate (4 × 5 g/day; n = 8) or placebo ( n = 8) for 5 days. Pretest Tmax, CT, and RT were similar in Cr and placebo groups. Also in the posttest, Tmax and CT were similar between groups. However, posttest RT was decreased consistently by ∼20% ( P < 0.05) in the Cr group from the first to the last of the 12 contractions. In addition, the mean decrease in RT after Cr loading was positively correlated with pretest RT ( r = 0.82). It is concluded that Cr loading facilitates the rate of muscle relaxation during brief isometric muscle contractions without affecting torque production.

Effect of temperature on post-tetanic potentiation in human dorsiflexor muscles

2001 ◽  
Vol 79 (1) ◽  
pp. 49-58 ◽  
Author(s):  
E Roderich Gossen ◽  
Kerry Allingham ◽  
Digby G Sale
Keyword(s):  
Relaxation Time ◽  
Rise Time ◽  
Wave Amplitude ◽  
Test Period ◽  
Warm Water ◽  
Effect Of Temperature ◽  
Type I ◽  
M Wave ◽  
Exposure To Cold ◽  
Post Tetanic Potentiation

The effect of temperature on post-tetanic potentiation (PTP) has been examined in the muscles of small mammals but not in human skeletal muscle. We examined PTP in the ankle dorsiflexor muscles of 10 young men by evoking twitches before and after a 7-second tetanus at 100 Hz in a control (room air ~21°C) condition and after immersion of the lower leg in warm (45°C) and cold (10°C) water baths for 30 min. Exposure to cold decreased tetanus and pre-tetanus twitch peak torque, but increased rise time, half-relaxation time, and muscle action potential (M-wave) amplitude; exposure to warm water had little effect. PTP was smallest in cold exposure 5 s post-tetanus, but persisted throughout the 12 min test period, whereas PTP had subsided by 6 min post-tetanus in control and warm exposures. M-wave amplitude initially decreased after exposure to warm water, recovered, then decreased again by 11 min post-tetanus. In contrast, exposure to cold had no initial effect but did increase the M-wave amplitude during the last half of the 12 min test period, similar to that seen in the control. The greatest immediate decrease in rise time and half-relaxation time was observed in the control; however, by 12 min post-tetanus warm exposure showed the greatest increase in rise time and half-relaxation time above pre-tetanus values. The decrease in the unpotentiated twitch torque with cooling in human dorsiflexors is typical for muscles with a predominance of type I (slow) fibres. The effect of cold on PTP is similar to that seen previously in mammalian muscles with a predominance of type II (fast) fibres, although the underlying mechanism of the cooling effect appears to differ.Key words: contraction, muscle, twitch.

Solar-blind ultraviolet photodetection of an α-Ga2O3 nanorod array based on photoelectrochemical self-powered detectors with a simple, newly-designed structure

2019 ◽  
Vol 7 (23) ◽  
pp. 6867-6871 ◽  
Author(s):  
Junhua Zhang ◽  
Shujie Jiao ◽  
Dongbo Wang ◽  
Shiming Ni ◽  
Shiyong Gao ◽  
...  
Keyword(s):  
Ultraviolet Light ◽  
Decay Time ◽  
Rise Time ◽  
Nanorod Array ◽  
Fast Response ◽  
Solar Blind ◽  
Self Powered

A newly-designed photoelectrochemical self-powered detector is applied to an α-Ga2O3 nanorod array to realize the detection of solar-blind ultraviolet light (wavelengths below 300 nm) and fast response (rise time of 0.076 s and decay time of 0.056 s).

Postsynaptic Receptor Occupancy During Evoked Transmission at Striatal GABAergic Synapses In Vitro

2000 ◽  
Vol 84 (2) ◽  
pp. 771-779 ◽  
Author(s):  
Eva Rumpel ◽  
Jan C. Behrends
Keyword(s):  
Time Constant ◽  
Decay Time ◽  
Rise Time ◽  
Receptor Occupancy ◽  
Decay Time Constant ◽  
Peak Amplitude ◽  
Postsynaptic Currents ◽  
Quantal Size ◽  
Convolution Model ◽  
Quantal Responses

The effect of benzodiazepines (BZs) on GABAA-ergic synaptic responses depends on the control receptor occupancy: the BZ-induced enhancement of receptor affinity can lead to greater peak amplitudes of quantal responses only when, under normal conditions, receptors are not fully saturated at peak. Based on this fact, receptor occupancy at the peak of spontaneous miniature inhibitory postsynaptic currents (mIPSCs) has been assessed in various mammalian neuronal preparations. To use the same principle with compound (or multiquantal), action potential–evoked IPSCs, complications introduced by quantal asynchrony in conjunction with the BZ-induced increase in the decay time of the quantal responses have to be overcome. We used a simple analytic convolution model to calculate expected changes in the rise time and amplitude of postsynaptic currents when the decay time constant, but not the peak amplitude, of the underlying quantal responses is increased, this being the expected BZ effect at saturated synapses. Predictions obtained were compared with the effect of the BZ flunitrazepam on IPSCs recorded in paired pre- and postsynaptic whole cell voltage-clamp experiments on striatal neurons in cell culture. In 22 pairs, flunitrazepam (500 nM) reliably prolonged the decay of IPSCs (49 ± 19%, mean ± SE) and in 18 of 22 cases produced an enhancement in their peak amplitude that varied markedly between 3 and 77% of control (26.0 ± 5.3%). The corresponding change in rise time, however (+0.38 ± 0.11 ms, range −0.8 to +1.3 ms) was far smaller than calculated for the observed changes in peak amplitude assuming fixed quantal size. Because therefore an increase in quantal size is required to explain our findings, postsynaptic GABAA receptors were most likely not saturated during impulse-evoked transmission at these unitary connections. The peak amplitudes of miniature IPSCs in these neurons were also increased by flunitrazepam (500 nM, +26.8 ± 6.6%), and their decay time constant was increased by 26.3 ± 7.3%. Using these values in our model led to a slight overestimate of the change in compound IPSC amplitude (+28 to +30%).

Luminescence différée d'une solution organique vitreuse photoactivée et transition vitreuse

1977 ◽  
Vol 55 (13) ◽  
pp. 2517-2522 ◽  
Author(s):  
D. Ceccaldi
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Kinetic Theory ◽  
Rise Time ◽  
Time Dependent ◽  
Glassy Matrix ◽  
Temperature Dependent

A general kinetic theory is used to explain the shapes of photoionized sample luminescence curves perturbed by thermal jumps (Δ ∼ 1 K, rise time ∼ 1 s). The samples studied are photoactivated organic vitreous solutions of TMPD/MCH 10−3 M and TMPD/3-MP 10−3 M. The experiments are performed within a temperature range (63–91 K) which includes the glass transition temperature Tg. It is shown that there is a slow diffusion of the trapped electrons towards the cation and competition between thermal detrapping and tunneling. The tunneling/thermal detrapping ratio Y is not time dependent during an isothermal luminescence and is only slowly temperature dependent if T ≤ Ty. Ty is very close to Tg. For T > Ty, Y decreases rapidly with T. The activation energy for thermal detrapping shows a maximum when the temperature reaches [Formula: see text] The glass transition temperature Tg may therefore be defined empirically as:[Formula: see text]Finally we obtain a glassy matrix relaxation time, τ, which decreases with T.

Fabrication and characterization of InN-based metal-semiconductor-metal infrared photodetectors prepared using sol–gel spin coated technique

2021 ◽  
pp. 2151024
Author(s):  
Zhi Yin Lee ◽  
Sha Shiong Ng
Keyword(s):  
Thin Films ◽  
Decay Time ◽  
Rise Time ◽  
Indium Nitride ◽  
Sol Gel ◽  
Diffuse Reflectance Spectrum ◽  
Ultra Violet ◽  
Nucleation Layer ◽  
Metal Semiconductor Metal

We report on the growth and characterization of undoped indium nitride (InN) thin films grown on a silicon substrate. The InN thin films were grown on aluminium nitride (AlN) template with gallium nitride (GaN) nucleation layer using a relatively simple and low-cost sol–gel spin coating method. The crystalline structure and optical properties of the deposited films were investigated. X-ray diffraction and Raman results revealed that InN thin films with wurtzite structure were successfully grown. For InN thin film grown on a substrate with the GaN nucleation layer, its strain and dislocation density are lower than that of the substrate with the AlN nucleation layer. From the ultra-violet-visible diffuse reflectance spectrum analysis, the energy bandgap of the InN thin films with the GaN layer was 1.70 eV. The potential application of the sol–gel spin-coated InN thin films was also explored. Metal–semiconductor–metal (MSM) infrared (IR) photodetectors were fabricated by depositing the platinum contacts using two interdigitated electrodes metal mask on the samples. The finding shows that the device demonstrates good sensitivity and repeatability towards IR excitation at a wavelength of 808 nm. The photodetector characteristics at dark and photocurrent conditions such as Schottky barrier height (SBH) and ideality factor are determined. Upon exposure to the IR source at 3V applied bias, InN/AlN/Si device configuration displays rapid rise time of 0.85 s and decay time of 0.78 s, while InN/GaN/AlNSi demonstrates slow rise time of 7.45 s and decay time of 13.75 s.

Luminescence Properties of Yb- and Nd- Implanted CdS

1993 ◽  
Vol 301 ◽  
Author(s):  
A. K. Alshawa ◽  
H. J. Lozykowski ◽  
T. Li ◽  
I. Brown
Keyword(s):  
Decay Time ◽  
Rise Time ◽  
Pulse Method ◽  
Excitation Power ◽  
Emission Lines ◽  
Luminescence Properties ◽  
Time Resolved ◽  
Thermal Pulse ◽  
Pl Spectra ◽  
Ion Laser

ABSTRACTThe photoluminescence (PL) and time resolved spectra of Nd- and Yb-implanted CdS samples are studied under pulsed and CW excitations using Ar+ ion laser for different excitation intensities and temperature (9 - 300 K). The samples were annealed under different conditions using the thermal-pulse method. For CdS:Nd, the PL spectra was recorded in the range 890-930 nm (transitions 4F3/2→4I9/2) and for CdS:Yb it was recorded in the range 985 - 1010 nm (transitions 2F5/2 →2F7/2). The Rise time and decay time were studied for both CdS:Nd and CdS:Yb at different emission lines as a function of temperature and excitation power.

scholarly journals An analysis of the continuum light in the 3500 – 8500Å region from a flare observed on the dwarf M star Gliese 234AB (= V577 Mon)

1989 ◽  
Vol 104 (2) ◽  
pp. 91-94
Author(s):  
J.G. Doyle ◽  
G.H.J. van den Oord ◽  
C.J. Butler
Keyword(s):  
Energy Density ◽  
Decay Time ◽  
Rise Time ◽  
Near Infrared ◽  
Impulsive Phase ◽  
Frequency Interval ◽  
Flare Energy ◽  
The Continuum

AbstractRelative energies are given for the U, B, V, R and I bands for a-3.8 magnitude U-band flare observed on the dwarf dMe star Gl 234 AB on 28 Feb 1985. This flare had a 45 second rise time and 20 minute decay time. The total flare energy from all five bands during the flare was 7 1031 erg, 34% of this total was from the U-band and 20% from the two near infrared R and I bands. The energy density (per frequency interval) implied a rising continuum towards the red, however this only lasted for approximately 20-40 seconds, i.e. during the impulsive phase, after-which the excess flare emission could not be detected in tlie near infrared bands. Of the various models fitted to the flare data (i.e. optical synchrotron, bound-free emission and free-free emission), bound-free emission seems the most promising.

scholarly journals Mechanisms Underlying the Enhancement of Excitatory Synaptic Transmission in Basolateral Amygdala Neurons of the Kindling Rat

1998 ◽  
Vol 80 (2) ◽  
pp. 638-646 ◽  
Author(s):  
Y. Shoji ◽  
E. Tanaka ◽  
S. Yamamoto ◽  
H. Maeda ◽  
H. Higashi
Keyword(s):  
Electrical Stimulation ◽  
Synaptic Transmission ◽  
Time Constant ◽  
Decay Time ◽  
Rise Time ◽  
Basolateral Amygdala ◽  
Stria Terminalis ◽  
Postsynaptic Potentials ◽  
Epileptiform Discharges ◽  
Stimulation Of

Shoji, Y., E. Tanaka, S. Yamamoto, H. Maeda, and H. Higashi. Mechanisms underlying the enhancement of excitatory synaptic transmission in basolateral amygdala neurons of the kindling rat. J. Neurophysiol. 80: 638–646, 1998. To elucidate the mechanism underlying epileptiform discharges in kindled rats, synaptic responses in kindled basolateral amygdala neurons in vitro were compared with those from control rats by using intracellular and whole cell patch-clamp recordings. In kindled neurons, electrical stimulation of the stria terminalis induced epileptiform discharges. The resting potential, apparent input resistance, current-voltage relationship of the membrane, and the threshold, amplitude, and duration of action potentials in kindled neurons were not different from those in control neurons. The electrical stimulation of stria terminalis elicited excitatory postsynaptic potentials (EPSPs) and dl-2-amino-5-phosphonopentanoic acid (AP5)-sensitive and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)-sensitive excitatory postsynaptic currents (EPSCs). The amplitude of evoked EPSPs and of evoked AP5-sensitive and CNQX-sensitive EPSCs were enhanced markedly, whereas fast and slow inhibitory postsynaptic potentials (IPSPs) induced by electrical stimulation of lateral amygdaloid nucleus were not significantly different. The rise time and the decay time constant of the evoked CNQX-sensitive EPSCs were shortened, whereas the rise time of the evoked AP5-sensitive EPSCs was shortened, but the decay time constants were not significantly different. In both tetrodotoxin (TTX)-containing medium and low Ca2+ and TTX-containing medium, the frequency and amplitude of spontaneous EPSCs were increased in kindled neurons. These increases are presumably due to nearly synchronous multiquantal events resulted from the increased probability of Glu release at the nerve terminals. The rise time of evoked CNQX- and AP5-sensitive EPSCs and the decay time constant of evoked CNQX-sensitive EPSCs were shortened, suggesting that excitatory synapses at the proximal dendrite and/or the soma in kindled neurons may contribute more effectively to generate evoked EPSCs than those at distal dendrites. In conclusion, the increases in the amplitudes of spontaneous and evoked EPSCs and in the frequency of spontaneous EPSCs may contribute to the epileptiform discharges in kindled neurons.

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