Theoretical model of intravascular paramagnetic tracers effect on tissue relaxation

DEFF Research Database (Denmark)

Kjølby, Birgitte Fuglsang; Østergaard, Leif; Kiselev, Valerij G

2006-01-01

The concentration of MRI tracers cannot be measured directly by MRI and is commonly evaluated indirectly using their relaxation effect. This study develops a comprehensive theoretical model to describe the transverse relaxation in perfused tissue caused by intravascular tracers. The model takes...... into account a number of individual compartments. The signal dephasing is simulated in a semianalytical way by embedding Monte Carlo simulations in the framework of analytical theory. This approach yields a tool for fast, realistic simulation of the change in the transverse relaxation. The results indicate...... with bulk blood. The enhancement of relaxation in tissue is due to the contrast in magnetic susceptibility between blood vessels and parenchyma induced by the presence of paramagnetic tracer. Beyond the perfusion measurements, the results can be applied to quantitation of functional MRI and to vessel size...

Relaxation effects in ferrous complexes

International Nuclear Information System (INIS)

Nicolini, C.; Mathieu, J.P.; Chappert, J.

1976-01-01

The slow relaxation mechanism of the Fe 2+ ion in the tri-fluorinated TF(acac) and hexafluorinated HF(acac) complexes of Fe(II) acetylacetonate was investigated. The 300K and 77K Moessbauer spectra for TF(acac) consist in a slightly asymmetric quadrupole doublet. On the contrary, at 4.2K the higher energy line is strongly widened; that is typical of a slowing down in the electron relaxation frequency [fr

The Effect of Relaxation and Positive Self-Talk on Symptoms of Premenstrual Syndrome

Directory of Open Access Journals (Sweden)

Kimiyaee Asadi

2016-05-01

Full Text Available Background Premenstrual syndrome (PMS is characterized by recurrent, moderate-to-severe affective, physical, and behavioral symptoms that develop during the luteal menstrual cycle and disappear within a few days of menstruation. Objectives This article aims to identify the effects of relaxation, positive self-talk, and a combination of relaxation and positive self-talk on premenstrual syndrome. Methods In this quasi-experimental study, 80 women with PMS disorder were selected using a simple random sampling method, in Hamadan, west of Iran. They were randomly divided into four groups. The first and second groups underwent positive self-talk and relaxation, respectively. The third group experienced positive self-talk and relaxation at the same time. The fourth group did not receive any treatment. The duration of treatment was 8 one-hour sessions. Data were collected using a PMS symptom severity questionnaire. All groups were followed up for six months after the intervention. Finally, data analysis was performed using SPSS version 18 for ANCOVA and Bonferroni tests. Results The results showed that compared to the control group, relaxation (23.2 and positive self-talk (21.25 treatment methods alone can reduce PMS (P < 0.001. On the other hand, a combined (relaxation + positive self-talk treatment method (13.75 was more effective in reducing PMS compared to relaxation or positive self-talk alone. Conclusions It seems that psychological therapy based on relaxation and positive self-talk can be significantly effective in reducing PMS.

Effective temperature in relaxation of Coulomb glasses.

Science.gov (United States)

Somoza, A M; Ortuño, M; Caravaca, M; Pollak, M

2008-08-01

We study relaxation in two-dimensional Coulomb glasses up to macroscopic times. We use a kinetic Monte Carlo algorithm especially designed to escape efficiently from deep valleys around metastable states. We find that, during the relaxation process, the site occupancy follows a Fermi-Dirac distribution with an effective temperature much higher than the real temperature T. Long electron-hole excitations are characterized by T(eff), while short ones are thermalized at T. We argue that the density of states at the Fermi level is proportional to T(eff) and is a good thermometer to measure it. T(eff) decreases extremely slowly, roughly as the inverse of the logarithm of time, and it should affect hopping conductance in many experimental circumstances.

The Effect of Relaxation Interventions on Cortisol Levels in HIV-Sero-Positive Women

Science.gov (United States)

Jones, Deborah; Owens, Mary; Kumar, Mahendra; Cook, Ryan; Weiss, Stephen M.

2016-01-01

Purpose Activation of the hypothalamic–pituitary–adrenal axis, assessed in terms of cortisol levels, may enhance the ability of HIV to infect lymphocytes and downregulate the immune system, accelerating disease progression. This study sought to determine the effects of relaxation techniques on cortisol levels in HIV-sero-positive women. Methods Women (n = 150) were randomized to a group cognitive–behavioral stress management (CBSM) condition or an individual information condition and underwent 3 types of relaxation training (progressive muscle relaxation, imagery, and autogenic training). Cortisol levels were obtained pre- and postrelaxation. Results Guided imagery was effective in reducing cortisol in the group condition (t = 3.90, P < .001), and muscle relaxation reduced cortisol in the individual condition (t = 3.11, P = .012). Among participants in the group condition attending all sessions, the magnitude of pre- to postsession reduction became greater over time. Conclusions Results suggest that specific relaxation techniques may be partially responsible for cortisol decreases associated with relaxation and CBSM. PMID:23715264

Is it more effective group relaxation than individual to reduce anxiety in specific phobias?

Directory of Open Access Journals (Sweden)

Julián Carretero Román

2009-05-01

Full Text Available Relaxation is a standard technique used by nurses to reduce the level of anxiety. It seems that their implementation on a group can bring certain benefits compared with individual relaxation. This outline is intended to raise this hypothesis in caring for individuals diagnosed with specific phobia, by approaching the problem from the cognitive behavioural therapy perspective. In addition, it seeks to evaluate the usefulness of the nurse intervention relaxation to reduce the level of anxiety, in turn comparing the results obtained using an indicator of the scale of results NOC and the Hamilton Anxiety Scale. The phobia is a specific entity underdiagnosed, whose prevalence is about 10%. Those affected can live a really limited and debilitating, deteriorating quality of life. The community mental health nurses are in a unique position to participate in the cognitive behavioural therapy through relaxation, which will allow them to reduce the level of anxiety when people establish contact with the phobic stimulus. Methodology: quasi-experimental study in specific phobia diagnosed, 20 to 40 years old adults attending for the first time to the mental health facility derived from primary care. Both the control group as the pilot will be treated by conducted cognitive-behavioural psychotherapy individualized according to the therapeutic protocol MSC, except in terms of relaxation, which in the experimental group will be conducted at the group level. The effectiveness of treatment will be assessed with the Hamilton anxiety scale and the likert type scale of outcome indicators NOC "stress level" with 3 measurements, before starting, immediately after completing the sessions of relaxation and three months later, checking the decline in the average level of anxiety.

Grid Cell Relaxation Effects on the High Frequency Vibration Characteristics

International Nuclear Information System (INIS)

Ryu, Joo-Young; Eom, Kyong-Bo; Jeon, Sang-Youn; Kim, Jae-Ik

2015-01-01

The plate structure of the grid of fuel assembly is always exposed to serious vortex induced vibration. Also, High Frequency flow induced Vibration (HFV) is primarily generated by vortex-shedding effect. When it comes to grid design as a fuel assembly component, HFV should be considered in advance since it is one of the critical factors. Excessive HFV has a possibility of making degradation of the fuel reliability that is directly related to the fuel robustness and operating performance. KEPCO NF (KNF) has performed HFV tests with various grid designs. While studying the HFV characteristics through the HFV tests, it has been observed that HFV amplitudes show different levels according to grid cell relaxation. It means that the testing could give different interpretations due to the condition of grid cell. Since the amount of relaxation is different under operating conditions and environments in a reactor, test specimens should be modified as much as possible to the real state of the fuel. Therefore, in order to consider the grid cell relaxation effects on the HFV tests, it is important to use cell sized or non-cell sized grids. The main focus of this study is to find out how the HFV characteristics such as amplitude and frequency are affected by grid cell relaxation. Three cases of the grid cell sized specimen which is nickel alloy were prepared and tested. Through the comparison of the test results, it could be concluded that HFV amplitudes show decreasing trend according to the grid cell relaxation in the case of nickel alloy grid. It is also possible to expect the tendency of grid cell relaxation of a zirconium alloy grid based on test results

The effects of bone on proton NMR relaxation times of surrounding liquids

Science.gov (United States)

Davis, C. A.; Genant, H. K.; Dunham, J. S.

1986-01-01

Preliminary attempts by our group at UCSF to assess fat content of vertebral marrow in the lumbar spine using relaxation time information demonstrated that the presence of trabecular bone affects relaxation times. The objective of this work was a thorough study of the effects of bone on NMR relaxation characteristics of surrounding liquids. Trabecular bone from autopsy specimens was ground up and sifted into a series of powders with graded densities ranging from 0.3 gm/cc to 0.8 gm/cc. Each powder was placed first in n-saline and then in cottonseed oil. With spectroscopy, spin-lattice relaxation times (T1) and effective spin-spin relaxation times (T2*) were measured for each liquid in each bone powder. As bone density and surface to volume ratio increased, T1 decreased faster for saline than for oil. T2* decreased significantly for both water and oil as the surface to volume ratio increased. It was concluded that effects of water on T1 could be explained by a surface interaction at the bone/liquid interface, which restricted rotational and translational motion of nearby molecules. The T1s of oil were not affected since oil molecules are nonpolar, do not participate in significant intermolecular hydrogen bonding, and therefore would not be expected to interact strongly with the bone surface. Effects on T2* could be explained by local magnetic field inhomogeneities created by discontinuous magnetic susceptibility near the bone surface. These preliminary results suggest that water in contact with trabecular bone in vivo will exhibit shortened relaxation times.

Non-linear effects in the Snoek relaxation of Nb-O

International Nuclear Information System (INIS)

Hermida, E.B.; Povolo, F.

1996-01-01

Internal friction peaks measured as a function of temperature or frequency have been associated to non-linear processes only after studying how the amplitude of the applied stress affects the relaxation process. Here it is demonstrated that the partial derivative of the internal friction with respect to the frequency at constant temperature is a useful tool to determine that non-linear effects are involved. This analysis applied to actual data of the Snoek relaxation in Nb-O, reveals that at high interstitial contents non-linear effects appear. (orig.)

Effect of the initial stage of annealing on modeling of enthalpy relaxation in a hyperquenched glass

DEFF Research Database (Denmark)

Zhang, Yanfei; Guo, Xiaoju; Yue, Yuanzheng

2013-01-01

One of the major challenges in glass relaxation study is to establish a universal model describing the enthalpy relaxation in both the hyperquenched glass (HQG) (i.e., far from equilibrium) and the partially annealed hyperquenched glass(AHQG). In particular, the detailed features of the enthalpy ...... proposed composite relaxation function [L. Hornboell, et al., Chem. Phys. Lett. 1-3 (2010) 37] is a reasonable approach for describing those features. In addition, our modeling results imply that the structural heterogeneity plays a crucial role in relaxation of HQG....

Nernst effect beyond the relaxation-time approximation

OpenAIRE

Pikulin, D. I.; Hou, Chang-Yu; Beenakker, C. W. J.

2011-01-01

Motivated by recent interest in the Nernst effect in cuprate superconductors, we calculate this magneto-thermo-electric effect for an arbitrary (anisotropic) quasiparticle dispersion relation and elastic scattering rate. The exact solution of the linearized Boltzmann equation is compared with the commonly used relaxation-time approximation. We find qualitative deficiencies of this approximation, to the extent that it can get the sign wrong of the Nernst coefficient. Ziman's improvement of the...

Load dependence of left ventricular contraction and relaxation. Effects of caffeine.

Science.gov (United States)

Leite-Moreira, A F; Correia-Pinto, J; Gillebert, T C

1999-08-01

Load dependence of left ventricular (LV) contraction and relaxation was investigated at baseline and after alteration of intracellular calcium handling by caffeine. Afterload was increased by aortic clamp occlusions (n = 281) in anesthetized open-chest dogs (n = 7). Control and first heartbeat after the intervention were considered for analysis. Caffeine (50 mg/kg, iv) had no inotropic effect. The systolic LV pressure (LVP), developed in response to aortic occlusion, decreased as ejection proceeded and this pressure generating capacity was not affected by caffeine. Late-systolic aortic occlusions induced premature onset and accelerated rate of initial LVP fall at baseline and similarly after caffeine. Graded diastolic aortic occlusions induced systolic LVP elevations of various magnitudes. Smaller LVP elevations prolonged ejection and accelerated LVP fall, while larger elevations had opposite effects. The transition from acceleration to deceleration was observed at 83.1 +/- 1.1% of peak isovolumetric LVP at baseline and at lower loads, at 77.6 +/- 1.2%, after caffeine (p caffeine (p dependence of relaxation, was also modified by caffeine. Caffeine affected LV relaxation without altering contractility. As a consequence contraction-relaxation coupling was modified by caffeine. These results might help to understand load dependence of relaxation in conditions where intracellular calcium handling is altered.

Relaxant effects of Ocimum basilicum on guinea pig tracheal chains and its possible mechanism(s

Directory of Open Access Journals (Sweden)

Mohammad Hossein Boskabady

2005-01-01

Full Text Available Therapeutic effects of Ocimum basilicum on respiratory diseases especially dyspnea have been reported in Iranian ancient medical books. In the present study, the relaxant effects of macerated and soxhlet extracts of this plant on tracheal chains of guinea pigs were evaluated. The relaxant effects of 4 cumulative concentrations of macerated and soxhlet extracts (0.25, 0.5, 0.75 and 1.0 W/V in comparison with saline as negative control and 4 cumulative concentrations of theophylline (0.25, 0.5, 0.75, and 1.0 mM as positive control were examined on precontracted tracheal chains of two groups of 6 guinea pig by 60 mM KCl (group 1 and 10 µM methacholine (group 2. Decrease in contractile tone of tracheal chains was considered as relaxant effect. In group 1 experiments only the last two higher concentrations of theophylline showed significant relaxant effect compared to that of saline (p<0.001 for both concentrations, which were significantly greater than those of macerated and soxhlet extracts (p<0.001 for all cases and in group 2 experiments both macerated and soxhlet extracts showed concentrationdependent relaxant effects compared to that of saline (p<0.05 to p<0.001 for both extracts. There were significant differences between the relaxant effects of both extracts with those of theophylline in group 2 experiments (p<0.01 to p<0.001. The relaxant effects of macerated and soxhlet extracts in group 1 were significantly lower than those of groups 2. These results showed a potent relaxant effect of Ocimum basilicum on tracheal chains of guinea pigs which were lower than theophylline at concentrations used.

(-)-Epicatechin-induced relaxation of isolated human saphenous vein: Roles of K+ and Ca2+ channels.

Science.gov (United States)

Marinko, Marija; Jankovic, Goran; Nenezic, Dragoslav; Milojevic, Predrag; Stojanovic, Ivan; Kanjuh, Vladimir; Novakovic, Aleksandra

2018-02-01

In this study, we aimed to investigate relaxant effect of flavanol (-)-epicatechin on the isolated human saphenous vein (HSV), as a part of its cardioprotective action, and to define the mechanisms underlying this vasorelaxation. (-)-Epicatechin induced a concentration-dependent relaxation of HSV pre-contracted by phenylephrine. Among K + channel blockers, 4-aminopyridine, margatoxin, and iberiotoxin significantly inhibited relaxation of HSV, while glibenclamide considerably reduced effects of the high concentrations of (-)-epicatechin. Additionally, (-)-epicatechin relaxed contraction induced by 80 mM K + , whereas in the presence of nifedipine produced partial relaxation of HSV rings pre-contracted by phenylephrine. In Ca 2+ -free solution, (-)-epicatechin relaxed contraction induced by phenylephrine, but had no effect on contraction induced by caffeine. A sarcoplasmic reticulum Ca 2+ -ATPase inhibitor, thapsigargin, significantly reduced relaxation of HSV produced by (-)-epicatechin. These results demonstrate that (-)-epicatechin produces endothelium-independent relaxation of isolated HSV rings. Vasorelaxation to (-)-epicatechin probably involves activation of 4-aminopyridine- and margatoxin-sensitive K V channels, BK Ca channels, and at least partly, K ATP channels. In addition, not only the inhibition of extracellular Ca 2+ influx, but regulation of the intracellular Ca 2+ release, via inositol-trisphosphate receptors and reuptake into sarcoplasmic reticulum, via stimulation of Ca 2+ -ATPase, as well, most likely participate in (-)-epicatechin-induced relaxation of HSV. Copyright © 2017 John Wiley & Sons, Ltd.

Chemical exchange effects during refocusing pulses in constant-time CPMG relaxation dispersion experiments

International Nuclear Information System (INIS)

Myint, Wazo; Ishima, Rieko

2009-01-01

In the analysis of the constant-time Carr-Purcell-Meiboom-Gill (CT-CPMG) relaxation dispersion experiment, chemical exchange parameters, such as rate of exchange and population of the exchanging species, are typically optimized using equations that predict experimental relaxation rates recorded as a function of effective field strength. In this process, the effect of chemical exchange during the CPMG pulses is typically assumed to be the same as during the free-precession. This approximation may introduce systematic errors into the analysis of data because the number of CPMG pulses is incremented during the constant-time relaxation period, and the total pulse duration therefore varies as a function of the effective field strength. In order to estimate the size of such errors, we simulate the time-dependence of magnetization during the entire constant time period, explicitly taking into account the effect of the CPMG pulses on the spin relaxation rate. We show that in general the difference in the relaxation dispersion profile calculated using a practical pulse width from that calculated using an extremely short pulse width is small, but under certain circumstances can exceed 1 s -1 . The difference increases significantly when CPMG pulses are miscalibrated

Quantization by stochastic relaxation processes and supersymmetry

International Nuclear Information System (INIS)

Kirschner, R.

1984-01-01

We show the supersymmetry mechanism resposible for the quantization by stochastic relaxation processes and for the effective cancellation of the additional time dimension against the two Grassmann dimensions. We give a non-perturbative proof of the validity of this quantization procedure. (author)

Relaxant effects of a hydroalcoholic extract of Ruta graveolens on isolated rat tracheal rings

Directory of Open Access Journals (Sweden)

Luis Águila

2015-01-01

Full Text Available BACKGROUND: Ruta graveolens L. (R. graveolens is a medicinal plant employed in non-traditional medicines that has various therapeutic properties, including anthelmintic, and vasodilatory actions, among others. We evaluated the trachea-relaxant effects of hydroalcoholic extract of R. graveolens against potassium chloride (KCl- and carbachol-induced contraction of rat tracheal rings in an isolated organ bath. RESULTS: The results showed that the airway smooth muscle contraction induced by the depolarizing agent (KCl and cholinergic agonist (carbachol was markedly reduced by R. graveolens in a concentration-dependent manner, with maximum values of 109 ± 7.9 % and 118 ± 2.6 %, respectively (changes in tension expressed as positive percentages of change in proportion to maximum contraction, at the concentration of 45 μg/mL (half-maximal inhibitory concentration IC50: 35.5 μg/mL and 27.8 μg/mL for KCl- and carbachol-induced contraction, respectively. Additionally, the presence of R. graveolens produced rightward parallel displacement of carbachol dose-response curves and reduced over 35 % of the maximum smooth muscle contraction. CONCLUSIONS: The hydroalcoholic extract of R. graveolens exhibited relaxant activity on rat tracheal rings. The results suggest that the trachea-relaxant effect is mediated by a non-competitive antagonistic mechanism. More detailed studies are needed to identify the target of the inhibition, and to determine more precisely the pharmacological mechanisms involved in the observed biological effects.

Effect of holographic grating period on its relaxation in a molecular glassy film

International Nuclear Information System (INIS)

Ozols, A; Augustovs, P; Kokars, V; Traskovskis, K; Saharov, D

2013-01-01

Holographic grating (HG) relaxation has been experimentally studied in 5,5,5-triphenylpentyl 4-((4-(bis(5,5,5-triphenylpentyl)amino) phenyl) diazenyl) benzoate molecular glassy film for HG periods (Λ) of 0.50, 2.0 and 8.6 μm. A strong effect of HG period on its relaxation is found manifesting itself differently in the volume and on the surface. The volume part of HG is fairly stable during 40 days if Λ > 0.50μm whereas the surface part of HG (most probably, surface relief grating) exhibits relaxational self-enhancement which is maximal at Λ = 8.6μm. It is proposed that thermostimulated directional mass transfer in the process of relaxation can be responsible for this relaxational self-enhancement. Weak HG recording and relatively fast HG decay takes place at Λ=0.50 μm. Therefore, effective chromophore photoorientation domain of about 0.2 μm is supposed

Effects of a pain programme on nurses' psychosocial, physical and relaxation interventions.

NARCIS (Netherlands)

Francke, A.L.; Luiken, J.B.; Garssen, B.; Huijer-Abu Saad, H.; Grypdonck, M.

1996-01-01

The effectiveness of a continuing education programme on pain assessment and management was investigated in 106 surgical cancer nurses. It was found that the programme led to a more positive attitude towards physical and relaxation interventions (such as the use of relaxation, distraction and

Effect of Progressive Muscle Relaxation on the Fatigue and Quality of Life Among Iranian Aging Persons

Directory of Open Access Journals (Sweden)

Ali Hassanpour-Dehkordi

2016-07-01

Full Text Available Since the elderly population is increasing rapidly in developing countries which may decrease the physical activity and exercise and in turn could affect the elderly’s quality of life, this study aimed to investigate the effect of progressive muscle relaxation on the elderly’s quality of life in Iran. In a randomized clinical trial, participants were randomly divided into intervention and control groups. For the intervention group, muscular progressive relaxation was run three days per week for three months (totally 36 sessions. In relaxation, a patient contract a group of his/her muscles in each step and relaxes them after five seconds and finally loosens all muscles and takes five deep breaths. Each session lasts for 45 minutes. The instrument of data gathering consisted of questionnaires on individual’s demographic data and quality of life SF-36. After intervention, quality of life increased significantly in the patients undergoing muscular progressive relaxation and fatigue severity decreased significantly in the intervention group compared to prior to intervention. In addition, there was a statistically significant difference in mean score of physical performance, restricted activity after physical problem, energy, socially function, physical pain, overall hygiene, and quality of life between intervention and control groups. By implementing regular and continuous progressive muscle relaxation, quality of life could be increased in different dimensions in the elderly and the context could be provided to age healthily and enjoy higher health and autonomy. Therefore, all of the therapeutic staffs are recommended to implement this plan to promote the elderly’s quality of life.

Effect of organo-clay on the dielectric relaxation response of silicone rubber

International Nuclear Information System (INIS)

Gharavi, N; Razzaghi-Kashani, M; Golshan-Ebrahimi, N

2010-01-01

Dielectric elastomers are light weight, low-cost, highly deformable and fast response smart materials capable of converting electrical energy into mechanical work or vice versa. Silicone rubber is a well-known dielectric elastomer which is used as actuator, and in order to enhance the efficiency of this smart material, compounding of silicone rubber with various fillers can be carried out. The effect of organically modified montmorillonite (OMMT) nano-clay on improvement of dielectric properties, actuation stress and its relaxation response was considered in this study. OMMT was dispersed in room temperature vulcanized (RTV) silicone rubber, and a composite film was cast. Using an in-house actuation set-up, it was shown that the actuation stress for a given electric field intensity is higher for composites than that for pristine silicone rubber. Also, the time-dependent actuation response of the samples was evaluated, and it was shown that the characteristic relaxation time of the actuation stress for composites is less than for the pristine rubber as a result of OMMT addition

Preparing Patients for Cancer Chemotherapy: Effect of Coping Preparation and Relaxation Interventions.

Science.gov (United States)

Burish, Thomas G.; And Others

1991-01-01

Sixty cancer chemotherapy patients were randomly assigned to one of four treatments: relaxation training with guided relaxation imagery (RT), general coping preparation (PREP), both RT and PREP, or routine clinic treatment only. Found that PREP intervention increased patients' knowledge of disease and treatment, reduced anticipatory side effects,…

Molecular motions in sucrose-PVP and sucrose-sorbitol dispersions-II. Implications of annealing on secondary relaxations.

Science.gov (United States)

Bhattacharya, Sisir; Bhardwaj, Sunny P; Suryanarayanan, Raj

2014-10-01

To determine the effect of annealing on the two secondary relaxations in amorphous sucrose and in sucrose solid dispersions. Sucrose was co-lyophilized with either PVP or sorbitol, annealed for different time periods and analyzed by dielectric spectroscopy. In an earlier investigation, we had documented the effect of PVP and sorbitol on the primary and the two secondary relaxations in amorphous sucrose solid dispersions (1). Here we investigated the effect of annealing on local motions, both in amorphous sucrose and in the dispersions. The average relaxation time of the local motion (irrespective of origin) in sucrose, decreased upon annealing. However, the heterogeneity in relaxation time distribution as well as the dielectric strength decreased only for β1- (the slower relaxation) but not for β2-relaxations. The effect of annealing on β2-relaxation times was neutralized by sorbitol while PVP negated the effect of annealing on both β1- and β2-relaxations. An increase in local mobility of sucrose brought about by annealing could be negated with an additive.

The Effects of Progressive Muscle Relaxation and Guided Imagery on gestational hypertension

OpenAIRE

Ranjkesh F

2017-01-01

Introduction: Hypertension is a common disorder in pregnancy. Although this disorder is accompanied by many difficulties in pregnancy, no effective therapy has still been found to treat it. One of the main methods in the treatment of hypertension is stress reducing programs such as relaxation and Guided Imagery. This study is aimed to evaluate the effects of progressive muscle relaxation and guided imagery on the gestational hypertension. Methods: The present study is a randomized clinical...

Capturing molecular multimode relaxation processes in excitable gases based on decomposition of acoustic relaxation spectra

Science.gov (United States)

Zhu, Ming; Liu, Tingting; Wang, Shu; Zhang, Kesheng

2017-08-01

Existing two-frequency reconstructive methods can only capture primary (single) molecular relaxation processes in excitable gases. In this paper, we present a reconstructive method based on the novel decomposition of frequency-dependent acoustic relaxation spectra to capture the entire molecular multimode relaxation process. This decomposition of acoustic relaxation spectra is developed from the frequency-dependent effective specific heat, indicating that a multi-relaxation process is the sum of the interior single-relaxation processes. Based on this decomposition, we can reconstruct the entire multi-relaxation process by capturing the relaxation times and relaxation strengths of N interior single-relaxation processes, using the measurements of acoustic absorption and sound speed at 2N frequencies. Experimental data for the gas mixtures CO2-N2 and CO2-O2 validate our decomposition and reconstruction approach.

The effects of music relaxation and muscle relaxation techniques on sleep quality and emotional measures among individuals with posttraumatic stress disorder

Directory of Open Access Journals (Sweden)

Iris Haimov

2012-07-01

Full Text Available Posttraumatic stress disorder (PTSD, an anxiety disorder with lifetime prevalence of 7.8%, is characterized by symptoms that develop following exposure to traumatic life events and that cause an immediate experience of intense fear, helplessness or horror. PTSD is marked by recurrent nightmares typified by the recall of intrusive experiences and by extended disturbance throughout sleep. Individuals with PTSD respond poorly to drug treatments for insomnia. The disadvantages of drug treatment for insomnia underline the importance of non-pharmacological alternatives. Thus, the present study had three aims: first, to compare the efficiency of two relaxation techniques (muscular relaxation and progressive music relaxation in alleviating insomnia among individuals with PTSD using both objective and subjective measures of sleep quality; second, to examine whether these two techniques have different effects on psychological indicators of PTSD, such as depression and anxiety; and finally, to examine how initial PTSD symptom severity and baseline emotional measures are related to the efficiency of these two relaxation methods. Thirteen PTSD patients with no other major psychiatric or neurological disorders participated in the study. The study comprised one seven-day running-in, no-treatment period, followed by two seven-day experimental periods. The treatments constituted either music relaxation or muscle relaxation techniques at desired bedtime. These treatments were randomly assigned. During each of these three experimental periods, subjects’ sleep was continuously monitored with a wrist actigraph (Ambulatory Monitoring, Inc., and subjects were asked to fill out several questionnaires concerned with a wide spectrum of issues, such as sleep, depression, and anxiety. Analyses revealed a significant increase in objective and subjective sleep efficiency and a significant reduction in depression level following music relaxation. Moreover, following music

Magneto-dependent stress relaxation of magnetorheological gels

KAUST Repository

Xu, Yangguang; Liu, Taixiang; Liao, G J; Lubineau, Gilles

2017-01-01

The stress relaxation behaviors of magnetorheological (MR) gels under stepwise shear loading are systematically investigated. The particle-enhanced effect, the magneto-induced effect, and the temperature-enhanced effect on the stress relaxation of MR gels are discussed. For further analysis of the magneto-induced stress relaxation mechanism in MR gels, a phenomenological model is established to describe the stress relaxation behavior of the matrix and the magnetic particle chains. All characteristic parameters introduced in the model, i.e. relaxation time, instantaneous modulus, and stable modulus, have well-defined physical meanings and are fitted based on the experimental results. The influence of each parameter on the macroscopic response is discussed and it is found that the relaxation stress induced by the magneto-mechanical coupling effect plays an important role in the stress relaxation process of MR gels.

Magneto-dependent stress relaxation of magnetorheological gels

KAUST Repository

Xu, Yangguang

2017-09-01

The stress relaxation behaviors of magnetorheological (MR) gels under stepwise shear loading are systematically investigated. The particle-enhanced effect, the magneto-induced effect, and the temperature-enhanced effect on the stress relaxation of MR gels are discussed. For further analysis of the magneto-induced stress relaxation mechanism in MR gels, a phenomenological model is established to describe the stress relaxation behavior of the matrix and the magnetic particle chains. All characteristic parameters introduced in the model, i.e. relaxation time, instantaneous modulus, and stable modulus, have well-defined physical meanings and are fitted based on the experimental results. The influence of each parameter on the macroscopic response is discussed and it is found that the relaxation stress induced by the magneto-mechanical coupling effect plays an important role in the stress relaxation process of MR gels.

Smooth muscle relaxant activity of Crocus sativus (saffron and its constituents: possible mechanisms

Directory of Open Access Journals (Sweden)

Amin Mokhtari-Zaer

2015-08-01

Full Text Available Saffron, Crocus sativus L. (C. sativus is rich in carotenoids and used in traditional medicine for treatment of various conditions such as coughs, stomach disorders, amenorrhea, asthma and cardiovascular disorders. These therapeutic effects of the plant are suggested to be due to its relaxant effect on smooth muscles. The effect of C. sativus and its constituents on different smooth muscles and the underlying mechanisms have been studied. Several studies have shown the relaxant effects of C. sativus and its constituents including safranal, crocin, crocetin and kaempferol on blood vessels. In addition, it was reported that saffron stigma lowers systolic blood pressure. The present review highlights the relaxant effects of C. sativus and its constituents on various smooth muscles. The possible mechanisms of this relaxing effect including activation of ß2-adrenoceptors, inhibition of histamine H1 and muscarinic receptors and calcium channels and modulation of nitric oxide (NO are also reviewed.

Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

Energy Technology Data Exchange (ETDEWEB)

Hsu, Chia-Wen [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China); Ma, Chen-Chi M., E-mail: ccma@che.nthu.edu.tw [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Tan, Chung-Sung [Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan (China); Li, Hsun-Tien [Material and Chemical Research Laboratories, Industrial Technology Research Institute, Hsinchu, Taiwan (China)

2015-07-15

The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ{sub 1}) and 753.6 h (ζ{sub 2}) at 55 °C. The ζ{sub 1} of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ{sub 2} can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. - Highlights: • The cured network conformations of DGEBA–PMSE hybrids were studied using DMA. • The structural relaxation behaviours of DGEBA–PMSE hybrids were studied using PALS. • The cured DGEBA–PMSE hybrids were interpenetrating polymer networks (IPNs). • PALS studies provided a quantitative demonstration of relaxation behaviours. • Double additive exponential model effectively predicted the relaxation times of hybrids.

Positron annihilation lifetime spectroscopy study on the structural relaxation of phenylmethylsiloxane-modified epoxy hybrids at different aging temperatures

International Nuclear Information System (INIS)

Hsu, Chia-Wen; Ma, Chen-Chi M.; Tan, Chung-Sung; Li, Hsun-Tien

2015-01-01

The cured network conformations and structural relaxation behaviours of the diglycidyl ether of bisphenol A (DGEBA)-methylhexahydrophthalic anhydride (MHHPA) modified with phenylmethylsiloxane-modified epoxy (PMSE) at different aging temperatures were studied using dynamic mechanical analysis (DMA) and positron annihilation lifetime spectroscopy (PALS). The DMA results revealed that the cured PMSE network can insert into the cured DGEBA network to form interpenetrating polymer networks (IPNs). The structural relaxation behaviours of DGEBA–PMSE-0.4 produced using DGEBA, PMSE, and MHHPA at a ratio of 0.6:0.4:1 by equivalent weight were studied using PALS at 150 °C and 55 °C. The aging-induced free volume relaxation parameters of DGEBA–PMSE-0.4 at 150 °C and 55 °C were investigated using the double additive exponential model and the Kohlrausch–Williams–Watts exponential model. For double additive exponential model, only one relaxation time (ζ) of 584.5 h was found at 150 °C; By contrast, there were two separate relaxation times of 37.4 h (ζ 1 ) and 753.6 h (ζ 2 ) at 55 °C. The ζ 1 of the IPNs hybrid can be attributed to the network relaxation of PMSE, and the ζ 2 can be attributed to the network relaxation of DGEBA at 55 °C. The results suggested the double additive exponential model can effectively predict DGEBA–PMSE hybrid relaxation behaviours. - Highlights: • The cured network conformations of DGEBA–PMSE hybrids were studied using DMA. • The structural relaxation behaviours of DGEBA–PMSE hybrids were studied using PALS. • The cured DGEBA–PMSE hybrids were interpenetrating polymer networks (IPNs). • PALS studies provided a quantitative demonstration of relaxation behaviours. • Double additive exponential model effectively predicted the relaxation times of hybrids

Dielectric relaxation of glass particles with conductive nano-coatings

Energy Technology Data Exchange (ETDEWEB)

Hussain, Shahid [Applied Technologies Department, QinetiQ Limited, Cody Technology Park, Farnborough, Hampshire, GU14 0LX (United Kingdom)

2009-03-21

This research focuses on the dielectric properties of particles consisting of glass cores with nanometre conductive coatings. The effects of the core glass particle shape (sphere, flake and fibre) and size are investigated for different coating characteristics over the frequency range 0.5-18 GHz. Experimental results for the coated glass particle combinations show the existence of a dielectric loss peak. This feature is associated with interfacial relaxation between the insulating core glass particle and the nanoscale conductive coating. The relaxation mechanism provides enhanced loss that is not observed in conventional solid metal particle composites. The results are fitted to a model, which shows that the relaxation frequency increases with increasing coating conductivity and thickness, with additional parameters identified for further particle optimizations.

[Effects of Monochord Music on Heart Rate Variability and Self-Reports of Relaxation in Healthy Adults].

Science.gov (United States)

Gäbel, Christine; Garrido, Natalia; Koenig, Julian; Hillecke, Thomas Karl; Warth, Marco

Music-based interventions are considered an effective and low-cost treatment option for stress-related symptoms. The present study aimed to examine the trajectories of the psychophysiological response in apparently healthy participants during a music-based relaxation intervention compared to a verbal relaxation exercise. 70 participants were assigned to either receptive live music (experimental group) or a prerecorded verbal relaxation exercise (control group). Self-ratings of relaxation were assessed before and after each intervention on visual analogue scales and the Relaxation Inventory (RI). The heart rate variability (HRV) was continuously recorded throughout the sessions. Statistical analysis focused on HRV parameters indicative of parasympathetic cardiovascular outflow. We found significant quadratic main effects for time on the mean R-R interval (heart rate), the high-frequency power of HRV (indicative of parasympathetic activity), and the self-ratings of relaxation in both groups. A significant group × time interaction was observed for the cognitive tension subscale of the RI. Participants in both groups showed psychophysiological changes indicative of greater relaxation over the course of the interventions. However, differences between groups were only marginal. Music might be effective in relieving stress and promoting relaxation by altering the autonomic nervous system function. Future studies need to explore the long-term outcomes of such interventions. © 2017 S. Karger GmbH, Freiburg.

Addition of rectus sheath relaxation incisions to emergency midline laparotomy for peritonitis to prevent fascial dehiscence.

Science.gov (United States)

Marwah, Sanjay; Marwah, Nisha; Singh, Mandeep; Kapoor, Ajay; Karwasra, Rajender Kumar

2005-02-01

The incidence of fascial dehiscence and incisional hernia after two methods for abdominal wound closure (rectus sheath relaxation incisions and conventional mass closure) was studied in a randomized prospective clinical trial in a consecutive series of 100 patients undergoing midline laparotomy for peritonitis. The two groups were well matched for etiologies of peritonitis, the surgical procedures performed, and the presence of known risk factors for fascial dehiscence. Fifty patients each were randomized either to the conventional continuous mass closure procedure or the rectus sheath relaxation incision technique (designed to increase wound elasticity and decrease tension in the suture line) using identical polypropylene sutures. The incidence of postoperative complications such as duration of ileus, chest infection, and wound infection were not statistically different between the two groups. The intensity of postoperative pain in the rectus sheath relaxation incision group was significantly less. The incidence of wound hematoma was significantly increased in the rectus sheath relaxation incision group. The incidences of fascial dehiscence (16% vs,28%; p cases of peritonitis using the rectus sheath relaxation technique is safe and less painful, provides increased wound elasticity and decreased tension on the suture line, and significantly decreases the incidence of wound dehiscence.

Calorimetric and relaxation properties of xylitol-water mixtures

Science.gov (United States)

Elamin, Khalid; Sjöström, Johan; Jansson, Helén; Swenson, Jan

2012-03-01

We present the first broadband dielectric spectroscopy (BDS) and differential scanning calorimetry study of supercooled xylitol-water mixtures in the whole concentration range and in wide frequency (10-2-106 Hz) and temperature (120-365 K) ranges. The calorimetric glass transition, Tg, decreases from 247 K for pure xylitol to about 181 K at a water concentration of approximately 37 wt. %. At water concentrations in the range 29-35 wt. % a plentiful calorimetric behaviour is observed. In addition to the glass transition, almost simultaneous crystallization and melting events occurring around 230-240 K. At higher water concentrations ice is formed during cooling and the glass transition temperature increases to a steady value of about 200 K for all higher water concentrations. This Tg corresponds to an unfrozen xylitol-water solution containing 20 wt. % water. In addition to the true glass transition we also observed a glass transition-like feature at 220 K for all the ice containing samples. However, this feature is more likely due to ice dissolution [A. Inaba and O. Andersson, Thermochim. Acta, 461, 44 (2007)]. In the case of the BDS measurements the presence of water clearly has an effect on both the cooperative α-relaxation and the secondary β-relaxation. The α-relaxation shows a non-Arrhenius temperature dependence and becomes faster with increasing concentration of water. The fragility of the solutions, determined by the temperature dependence of the α-relaxation close to the dynamic glass transition, decreases with increasing water content up to about 26 wt. % water, where ice starts to form. This decrease in fragility with increasing water content is most likely caused by the increasing density of hydrogen bonds, forming a network-like structure in the deeply supercooled regime. The intensity of the secondary β-relaxation of xylitol decreases noticeably already at a water content of 2 wt. %, and at a water content above 5 wt. % it has been replaced by a

Effects of Color Light and Relaxation Exercise Therapy on Adults with Learning Disabilities.

Science.gov (United States)

Rustigan, Carol J.

In a study at California State University, Sacramento, the effects of color light and relaxation exercise therapy were investigated with 16 students (ages 23 to 48) with learning disabilities. Therapy consisted of either 20 sessions viewing color light through a Lumatron instrument or 20 sessions listening to relaxation exercise tapes. Diagnostic…

Mechanical relaxation in glasses

International Nuclear Information System (INIS)

Hiki, Y.

2004-01-01

The basic properties of glasses and the characteristics of mechanical relaxation in glasses were briefly reviewed, and then our studies concerned were presented. Experimental methods adopted were viscosity, internal friction, ultrasonic attenuation, and Brillouin scattering measurements. The specimens used were several kinds of inorganic, organic, and metallic glasses. The measurements were mainly carried out from the room temperature up to the glass transition temperature, and the relaxation time was determined as a function of temperature. The 'double relaxation' composed of two Arrhenius-type relaxations was observed in many materials. In both relaxations, the 'compensation effect' showing a correlation of the pre-exponential factor and the activation energy was observed. These results were explained by considering the 'complex relaxation' due to cooperative motions of atoms or group of atoms. Values of activation energy near the glass transition determined by the various experimental methods were compared with each other

Effect of reorientation of anisotropic point defects on relaxation of crystal elastic coefficients of high order

International Nuclear Information System (INIS)

Topchyan, I.I.; Dokhner, R.D.

1977-01-01

The effect of reorientation of anisotropic point defects in uniform fields of elastic stresses on the relaxation of the elastic coefficients of a crystal was investigated in the nonlinear elasticity theory approximation. In calculating the interaction of point defects with elastic-stress fields was taken into consideration. The expression for the relaxations of the elasticity coefficients are obtained in an analytical form. The relaxation of the second-order elasticity coefficients is due to the dimentional interaction of a point defect with an applied-stress field, whereas the relaxation of the higher-order elasticity coefficients is determined both by dimentional and module effects

The Effects of Positive or Neutral Communication during Acupuncture for Relaxing Effects: A Sham-Controlled Randomized Trial

Directory of Open Access Journals (Sweden)

Annelie Rosén

2016-01-01

Full Text Available Introduction. The link between patient-clinician communication and its effect on clinical outcomes is an important clinical issue that is yet to be elucidated. Objective. Investigating if communication type (positive or neutral about the expected treatment outcome affected (i participants’ expectations and (ii short-term relaxation effects in response to genuine or sham acupuncture and investigating if expectations were related to outcome. Methods. Healthy volunteers (n=243, mean age of 42 were randomized to one treatment with genuine or sham acupuncture. Within groups, participants were randomized to positive or neutral communication, regarding expected treatment effects. Visual Analogue Scales (0–100 millimeters were used to measure treatment expectations and relaxation, directly before and after treatment. Results. Participants in the positive communication group reported higher treatment expectancy, compared to the neutral communication group (md 12 versus 6 mm, p=0.002. There was no difference in relaxation effects between acupuncture groups or between communication groups. Participants with high baseline expectancy perceived greater improvement in relaxation, compared to participants with low baseline levels (md 27 versus 15 mm, p=0.022. Conclusion. Our data highlights the importance of expectations for treatment outcome and demonstrates that expectations can be effectively manipulated using a standardized protocol that in future research may be implemented in clinical trials.

Relaxation in x-space magnetic particle imaging.

Science.gov (United States)

Croft, Laura R; Goodwill, Patrick W; Conolly, Steven M

2012-12-01

Magnetic particle imaging (MPI) is a new imaging modality that noninvasively images the spatial distribution of superparamagnetic iron oxide nanoparticles (SPIOs). MPI has demonstrated high contrast and zero attenuation with depth, and MPI promises superior safety compared to current angiography methods, X-ray, computed tomography, and magnetic resonance imaging angiography. Nanoparticle relaxation can delay the SPIO magnetization, and in this work we investigate the open problem of the role relaxation plays in MPI scanning and its effect on the image. We begin by amending the x-space theory of MPI to include nanoparticle relaxation effects. We then validate the amended theory with experiments from a Berkeley x-space relaxometer and a Berkeley x-space projection MPI scanner. Our theory and experimental data indicate that relaxation reduces SNR and asymmetrically blurs the image in the scanning direction. While relaxation effects can have deleterious effects on the MPI scan, we show theoretically and experimentally that x-space reconstruction remains robust in the presence of relaxation. Furthermore, the role of relaxation in x-space theory provides guidance as we develop methods to minimize relaxation-induced blurring. This will be an important future area of research for the MPI community.

Memory effects in the relaxation of a confined granular gas

Science.gov (United States)

Brey, J. Javier; de Soria, M. I. García; Maynar, P.; Buzón, V.

2014-09-01

The accuracy of a model to describe the horizontal dynamics of a confined quasi-two-dimensional system of inelastic hard spheres is discussed by comparing its predictions for the relaxation of the temperature in a homogenous system with molecular dynamics simulation results for the original system. A reasonably good agreement is found. Next the model is used to investigate the peculiarities of the nonlinear evolution of the temperature when the parameter controlling the energy injection is instantaneously changed while the system was relaxing. This can be considered as a nonequilibrium generalization of the Kovacs effect. It is shown that, in the low-density limit, the effect can be accurately described by using a simple kinetic theory based on the first Sonine approximation for the one-particle distribution function. Some possible experimental implications are indicated.

Nonmaxwell relaxation in disordered media: Physical mechanisms and fractional relaxation equations

International Nuclear Information System (INIS)

Arkhincheev, V.E.

2004-12-01

The problem of charge relaxation in disordered systems has been solved. It is shown, that due to the inhomogeneity of the medium the charge relaxation has a non-Maxwell character. The two physical mechanisms of a such behavior have been founded. The first one is connected with the 'fractality' of conducting ways. The second mechanism of nonexponential non-Maxwell behavior is connected with the frequency dispersion of effective conductivity of heterogeneous medium, initially consisting of conducting phases without dispersion. The new generalized relaxation equations in the form of fractional temporal integro-differential equations are deduced. (author)

Effect of lithium on endothelium-dependent and neurogenic relaxation of rat corpus cavernosum: role of nitric oxide pathway.

Science.gov (United States)

Sadeghipour, Hamed; Ghasemi, Mehdi; Ebrahimi, Farzad; Dehpour, Ahmad Reza

2007-02-01

Some studies have reported erectile dysfunction in patients receiving lithium through a mechanism that has not yet been defined. The aim of the present study was to verify the effect of acute lithium administration on the nonadrenergic noncholinergic (NANC)- and endothelium-mediated relaxation of rat isolated corpus cavernosum. The isolated rat corporeal strips were precontracted with phenylephrine hydrochloride (7.5 microM) and electrical field stimulation (EFS) was applied at different frequencies (2, 5, 10, and 15 Hz) to obtain NANC-mediated relaxation or relaxed by adding cumulative doses of acetylcholine (10nM-1mM) to obtain endothelium-dependent relaxation in the presence or absence of lithium (0.3, 0.5, 1, and 5mM). Also, effects of combining lithium (0.3mM) with 30 nM and 0.1 nM L-NAME (an NO synthase inhibitor) on NANC- and acetylcholine-mediated relaxation was investigated, respectively. Moreover, effects of combining lithium (1mM) with 0.1mM and 10 microM L-arginine (a precursor of NO) on NANC- and endothelium-mediated relaxation was assessed, respectively. Also, the effect of lithium (1mM) on relaxation to sodium nitroprusside (SNP; 1nM-1mM), an NO donor, was investigated. The NANC-mediated relaxation was significantly (Pacetylcholine in a concentration-dependent manner. Combination of lithium (0.3mM) with 30 and 0.1 nM L-NAME, which separately had a minimum effect on NANC- and endothelium-mediated relaxation, significantly (Pacetylcholine and EFS, it improved the inhibition by lithium (1mM) of relaxant responses to acetylcholine and EFS, respectively. Also, SNP produced similar concentration-dependent relaxations from both groups. Our experiments indicated that lithium likely by interfering with NO pathway in both endothelium and nitrergic nerve can result in impairment of both the endothelium- and NANC-mediated relaxation of rat corpus cavernosum.

The Effect of Phonon Relaxation Process on Absorption Spectra ...

African Journals Online (AJOL)

In this work we study the effect of phonon relaxation process on the absorption spectra using the Green's function technique. The Green's function technique which is widely used in many particle problems is used to solve the Kubo formula which describes the optical absorption process. Finally the configurational diagram is ...

Effect of guided relaxation and imagery on falls self-efficacy: a randomized controlled trial.

Science.gov (United States)

Kim, Bang Hyun; Newton, Roberta A; Sachs, Michael L; Glutting, Joseph J; Glanz, Karen

2012-06-01

To examine the effects of guided relaxation and imagery (GRI) on improvement in falls self-efficacy in older adults who report having a fear of falling. Randomized, controlled trial with allocation to GRI or guided relaxation with music of choice. General community. Ninety-one men and women aged 60 to 92. Participants were randomized to listen to a GRI audio compact disk (intervention group) or a guided relaxation audio compact disk and music of choice (control group) twice a week for 6 weeks for 10 minutes per session. Primary outcome measure was the Short Falls Efficacy Scale-International (FES-I). Secondary outcome measures were the Leisure Time Exercise Questionnaire (LTEQ) and the Timed Up and Go (TUG) mobility test. GRI participants reported greater improvements on the Short FES-I (P = .002) and LTEQ (P = .001) scores and shorter time on the TUG (P = .002) than the guided relaxation and music-of-choice group. GRI was more effective at increasing falls self-efficacy and self-reported leisure time exercise and reducing times on a simple mobility test than was guided relaxation with music of choice. GRI is an effective, simple, low-cost tool for older adults to improve falls self-efficacy and leisure time exercise behaviors. © 2012, Copyright the Authors Journal compilation © 2012, The American Geriatrics Society.

Effect of addition of V and C on strain recovery characteristics in Fe-Mn-Si alloy

International Nuclear Information System (INIS)

Lin Chengxin; Wang Guixin; Wu Yandong; Liu Qingsuo; Zhang Jianjun

2006-01-01

Shape recoverable strain, recovery stress and low-temperature stress relaxation characteristics in an Fe-17Mn-5Si-10Cr-4Ni (0.08C) alloy and an Fe-17Mn-2Cr-5Si-2Ni-1V (0.23C) alloy have been studied by means of X-ray diffraction, transmission electron microscopy and measurement of recoverable strain and recovery stress. The amount of stress-induced ε martensite under tensile deformation at room temperature, recoverable strain and recovery stress are increased obviously with addition V and C in Fe-Mn-Si alloy, which is owing to the influence of addition V and C on strengthening austenitic matrix. Addition of V and C in Fe-Mn-Si alloy is evidently effective to reduce the degree of low-temperature stress relaxation, for the dispersed VC particles 50-180 nm in size precipitated during annealing restrain the stress induced martensitic transformation

Characterization of the transverse relaxation rates in lipid bilayers

International Nuclear Information System (INIS)

Watnick, P.I.; Dea, P.; Chan, S.I.

1990-01-01

The 2H NMR transverse relaxation rates of a deuterated phospholipid bilayer reflect slow motions in the bilayer membrane. A study of dimyristoyl lecithin specifically deuterated at several positions of the hydrocarbon chains indicates that these motions are cooperative and are confined to the hydrocarbon chains of the lipid bilayer. However, lipid head group interactions do play an important role in modulating the properties of the cooperative fluctuations of the hydrocarbon chains (director fluctuations), as evidenced by the effects of various lipid additives on the 2H NMR transverse relaxation rates of the dimyristoyl lecithin bilayer

Dynamics of relaxed inflation

Science.gov (United States)

Tangarife, Walter; Tobioka, Kohsaku; Ubaldi, Lorenzo; Volansky, Tomer

2018-02-01

The cosmological relaxation of the electroweak scale has been proposed as a mechanism to address the hierarchy problem of the Standard Model. A field, the relaxion, rolls down its potential and, in doing so, scans the squared mass parameter of the Higgs, relaxing it to a parametrically small value. In this work, we promote the relaxion to an inflaton. We couple it to Abelian gauge bosons, thereby introducing the necessary dissipation mechanism which slows down the field in the last stages. We describe a novel reheating mechanism, which relies on the gauge-boson production leading to strong electro-magnetic fields, and proceeds via the vacuum production of electron-positron pairs through the Schwinger effect. We refer to this mechanism as Schwinger reheating. We discuss the cosmological dynamics of the model and the phenomenological constraints from CMB and other experiments. We find that a cutoff close to the Planck scale may be achieved. In its minimal form, the model does not generate sufficient curvature perturbations and additional ingredients, such as a curvaton field, are needed.

Effect of dislocations of forest on relaxation of mechanical stresses in irradiated zinc crystals

International Nuclear Information System (INIS)

Troitskij, O.A.; Kalymbetov, P.U.; Kusainov, S.G.; Shambulov, N.B.

1988-01-01

Effect of forest dislocations on the value of electron-plastic effect (EPE) in zinc crystals during their irradiation by accelerated electron packets is investigated. The following mechanical parameters are determined experimentally: total relaxation of voltages Δσ for 180s; change in reforming voltage Δσpl in single pulses of irradiation on the slope and bottom of relaxation curves. The results obtained testify to the effectiveness of forest dislocations as surmountable obstacles for the dislocations shiding in the basis plane

Effect of relaxation on working memory and the Bispectral Index of the EEG.

Science.gov (United States)

Hudetz, Judith A; Hudetz, Anthony G; Reddy, Diane M

2004-08-01

Beneficial effects of relaxation on cardiovascular and immune functions and on memory has been implied but an empirical relationship between task performance and anxiety reduction has not been reported. In this study, we investigated whether guided imagery of relatively short duration would decrease S-Anxiety and electroencephalogram Bispectral Index and improve working memory. 42 participants (age: M=39, SD=11, 14 men, 28 women, university students and VA Medical Center employees, recruited by their professor or by fellow employees) underwent relaxation by 16-min. guided imagery or no treatment (control). Spielberger's State-Trait Anxiety Inventory and the WAIS-III Letter-Number Sequencing Test were administered before and after relaxation. S-Anxiety and BIS Index decreased and the Letter-Number test score increased by 30% after relaxation but not in the control group. This score was higher for participants with low anxiety and BIS Index. There was no significant difference between the groups before treatment. The results suggest that guided imagery of short duration produces relaxation as measured by psychological and neurophysiological indices and improves working memory performance.

Milrinone relaxes pulmonary veins in guinea pigs and humans.

Directory of Open Access Journals (Sweden)

Annette D Rieg

Full Text Available INTRODUCTION: The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH. However, its action on pulmonary veins (PVs is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs and humans. MATERIAL AND METHODS: Precision-cut lung slices (PCLS were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL. RESULTS: In the IPL (GP, milrinone (10 µM lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP, milrinone relaxed naïve and pre-constricted PVs (120% and this relaxation was attenuated by inhibition of protein kinase G (KT 5823, adenyl cyclase (SQ 22536 and protein kinase A (KT 5720, but not by inhibition of NO-synthesis (L-NAME. In addition, milrinone-induced relaxation was dependent on the activation of K ATP-, BK Ca (2+- and Kv-channels. Human PVs also relaxed to milrinone (121%, however only if pre-constricted. DISCUSSION: Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on K ATP-, BK Ca (2+- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

Milrinone relaxes pulmonary veins in guinea pigs and humans.

Science.gov (United States)

Rieg, Annette D; Suleiman, Said; Perez-Bouza, Alberto; Braunschweig, Till; Spillner, Jan W; Schröder, Thomas; Verjans, Eva; Schälte, Gereon; Rossaint, Rolf; Uhlig, Stefan; Martin, Christian

2014-01-01

The phosphodiesterase-III inhibitor milrinone improves ventricular contractility, relaxes pulmonary arteries and reduces right ventricular afterload. Thus, it is used to treat heart failure and pulmonary hypertension (PH). However, its action on pulmonary veins (PVs) is not defined, although particularly PH due to left heart disease primarily affects the pulmonary venous bed. We examined milrinone-induced relaxation in PVs from guinea pigs (GPs) and humans. Precision-cut lung slices (PCLS) were prepared from GPs or from patients undergoing lobectomy. Milrinone-induced relaxation was studied by videomicroscopy in naïve PVs and in PVs pre-constricted with the ETA-receptor agonist BP0104. Baseline luminal area was defined as 100%. Intracellular cAMP was measured by ELISA and milrinone-induced changes of segmental vascular resistances were studied in the GP isolated perfused lung (IPL). In the IPL (GP), milrinone (10 µM) lowered the postcapillary resistance of pre-constricted vessels. In PCLS (GP), milrinone relaxed naïve and pre-constricted PVs (120%) and this relaxation was attenuated by inhibition of protein kinase G (KT 5823), adenyl cyclase (SQ 22536) and protein kinase A (KT 5720), but not by inhibition of NO-synthesis (L-NAME). In addition, milrinone-induced relaxation was dependent on the activation of K ATP-, BK Ca (2+)- and Kv-channels. Human PVs also relaxed to milrinone (121%), however only if pre-constricted. Milrinone relaxes PVs from GPs and humans. In GPs, milrinone-induced relaxation is based on K ATP-, BK Ca (2+)- and Kv-channel-activation and on cAMP/PKA/PKG. The relaxant properties of milrinone on PVs lead to reduced postcapillary resistance and hydrostatic pressures. Hence they alleviate pulmonary edema and suggest beneficial effects of milrinone in PH due to left heart disease.

Comparing the effects of relaxation technique and inhalation aromatherapy on fatigue in patients undergoing hemodialysis.

Science.gov (United States)

Hassanzadeh, Mohammadali; Kiani, Fatemeh; Bouya, Salehoddin; Zarei, Mohammad

2018-05-01

This study aimed to compare the effects of relaxation techniques on fatigue in hemodialysis patients. This clinical trial study was conducted on 105 hemodialysis patients. The subjects were categorized into three groups as: relaxation, aromatherapy and control. In the relaxation group, Benson muscle relaxation techniques were employed; in the aromatherapy group, the inhalation of two drops of 5% lavender essential oil used and the control group only received regular healthcare actions. Data collected by using brief fatigue inventory, before and after the intervention. Results of the current study indicated significant differences in the mean of changes in fatigue scores before and after the intervention between the relaxation and aromatherapy groups, but the difference was insignificant in the control group. Aromatherapy with lavender essential oil can decrease the level of fatigue in the patients undergoing hemodialysis compared to Benson relaxation techniques. Copyright © 2018 Elsevier Ltd. All rights reserved.

Mechanisms behind the relaxing effect of furosemide on the isolated rabbit ear artery

Energy Technology Data Exchange (ETDEWEB)

Tian, R.; Aalkjaer, C.; Andreasen, F. (Institute of Pharmacology, University of Aarhus, Aarhus (Denmark))

1991-01-01

The effect of furosemide on isometric contration and {sup 86}Rb uptake were studied in the isolated rabbit central ear artery (CEA). A concentration-dependent relaxing effect of furosemide (0.06 mM-1.0 mM) was found in vessel segments with intact endothelium. The maximal relaxation was 28.6+-3.9% (10). The effect was not diminished in segments deprived of endothelium, and removal of endothelium itself caused no change of the force development to electrical field stimualtion. The relaxing effect was time-dependent and stimulation-dependent and was not significantly affected by membrane depolarization induced by increasing external (K{sup +}) from 10 to 120 mM. The {sup 86}Rb uptake was inhibited by both furosemide and ouabain (8.0+-0.5(8) and 5.3+-0.5(8) versus 12.8+-0.9(16) nmol (K{sup +})x mm{sup -1}x(10 min.){sup -1} in the furosemide (1.0 mM), ouabain (1.0 mM) and control groups, respectively) without interaction between the two drugs. The {sup 86}Rb uptake was not further inhibited by increasing the furosemide concentration from 0.12 mM to 1.0 mM. Our results suggest: firstly, the direct relaxing effect of furosemide on isolated vessel segments in endothelium-independent and secondly, the inhibition of the Na{sup +}-K{sup +}-Cl{sup -} cotransport and a possible consequent hyperpolarization of the membrane is unlikely to be the sole mechanism responsible for the vasorelaxant effect of furosemide. The demonstrated direct effect on vascular tone may be of clinical importance in situations with very high plasma concentrations of the drug or very low concentrations of serum albumin. (aluthor).

Memory effects in the relaxation of the Gaussian trap model

Science.gov (United States)

Diezemann, Gregor; Heuer, Andreas

2011-03-01

We investigate the memory effect in a simple model for glassy relaxation, a trap model with a Gaussian density of states. In this model, thermal equilibrium is reached at all finite temperatures and we therefore can consider jumps from low to high temperatures in addition to the quenches usually considered in aging studies. We show that the evolution of the energy following the Kovacs protocol can approximately be expressed as a difference of two monotonously decaying functions and thus show the existence of a so-called Kovacs hump whenever these functions are not single exponentials. It is well established that the Kovacs effect also occurs in the linear response regime, and we show that most of the gross features do not change dramatically when large temperature jumps are considered. However, there is one distinguishing feature that only exists beyond the linear regime, which we discuss in detail. For the memory experiment with inverted temperatures, i.e., jumping up and then down again, we find a very similar behavior apart from an opposite sign of the hump.

Multiplied effect of heat and radiation in chemical stress relaxation

International Nuclear Information System (INIS)

Ito, Masayuki

1981-01-01

About the deterioration of rubber due to radiation, useful knowledge can be obtained by the measurement of chemical stress relaxation. As an example, the rubber coating of cables in a reactor containment vessel is estimated to be irradiated by weak radiation at the temperature between 60 and 90 deg C for about 40 years. In such case, it is desirable to establish the method of accelerated test of the deterioration. The author showed previously that the law of time-dose rate conversion holds in the case of radiation. In this study, the chemical stress relaxation to rubber was measured by the simultaneous application of heat and radiation, and it was found that there was the multiplied effect of heat and radiation in the stress relaxation speed. Therefore the factor of multiplication of heat and radiation was proposed to describe quantitatively the degree of the multiplied effect. The chloroprene rubber used was offered by Hitachi Cable Co., Ltd. The experimental method and the results are reported. The multiplication of heat and radiation is not caused by the direct cut of molecular chains by radiation, instead, it is based on the temperature dependence of various reaction rates at which the activated species reached the cut of molecular chains through complex reaction mechanism and the temperature dependence of the diffusion rate of oxygen in rubber. (Kako, I.)

Structural relaxation dynamics and annealing effects of sodium silicate glass.

Science.gov (United States)

Naji, Mohamed; Piazza, Francesco; Guimbretière, Guillaume; Canizarès, Aurélien; Vaills, Yann

2013-05-09

Here we report high-precision measurements of structural relaxation dynamics in the glass transition range at the intermediate and short length scale for a strong sodium silicate glass during long annealing times. We evidence for the first time the heterogeneous dynamics at the intermediate range order by probing the acoustic longitudinal frequency in the GHz region by Brillouin light scattering spectroscopy. Or, from in-situ Raman measurements, we show that relaxation is indeed homogeneous at the interatomic length scale. Our results show that the dynamics at the intermediate range order contains two distinct relaxation time scales, a fast and a slow component, differing by about a 10-fold factor below Tg and approaching to one another past the glass transition. The slow relaxation time agrees with the shear relaxation time, proving that Si-O bond breaking constitutes the primary control of structural relaxation at the intermediate range order.

Ex vivo relaxation effect of Cuscuta chinensis extract on rabbit corpus cavernosum.

Science.gov (United States)

Sun, Kai; Zhao, Chen; Chen, Xiang-Feng; Kim, Hye-Kyung; Choi, Bo-Ram; Huang, Yi-Ran; Park, Jong-Kwan

2013-01-01

The effect of Cuscuta chinensis extract on the rabbit penile corpus cavernosum (PCC) was evaluated in the present study. Penises obtained from healthy male New Zealand white rabbits (2.5-3.0 kg) were precontracted with phenylephrine (Phe, 10 µmol l(-1)) and then treated with various concentrations of Cuscuta chinensis extract (1, 2, 3, 4 and 5 mg ml(-1)). The change in penile tension was recorded, and cyclic nucleotides in the PCC were measured by radioimmunoassay (RIA). The interaction between Cuscuta chinensis and sildenafil was also evaluated. The result indicated that the PCC relaxation induced by Cuscuta chinensis extract was concentration-dependent. Pre-treatment with an nitric oxide synthase (NOS) inhibitor (Nω nitro-L-arginine-methyl ester, L-NAME), a guanylyl cyclase inhibitor (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, ODQ), or a protein kinase A inhibitor (KT 5720) did not completely inhibit the relaxation. Incubation of penile cavernous tissue with the Cuscuta chinensis extract significantly increased cyclic guanosine monophosphate (cGMP) and cyclic adenosine monophosphate (cAMP) in the PCC. Moreover, the Cuscuta chinensis extract significantly enhanced sildenafil-induced PCC relaxation. In conclusion, the Cuscuta chinensis extract exerts a relaxing effect on penile cavernous tissue in part by activating the NO-cGMP pathway, and it may improve erectile dysfunction (ED), which does not completely respond to sildenafil citrate.

Effects of distribution function nonequilibrium tails on relaxation and transfer processes in rarefied gases

International Nuclear Information System (INIS)

Grigoryev, Yu.N.; Mikhalitsyn, A.N.; Yanenko, N.N.

1984-01-01

Quantitative characteristics of the nonmonotone relaxation process are studied in a gas of pseudo-Maxwell molecules. Basic results are obtained by a direct numerical integration of the nonlinear Boltzmann equation. The evolution of initial distributions being finite or having exponential asymptotics of tails was researched. In particular, initial data obtained by selective excitation (absorption) against the Maxwell background encountered in laser physics problems have been considered. It is shown that under conditions of a developed effect of nonmonotone relaxation the overpopulation in the velocity range 4 <= upsilon <= 10 exceeds on the average 2-3 times the equilibrium value. For the given particles energy the excitation is preserved during t = 5/6 and the total relaxation time of the overpopulation wave reaches t asymptotically equals 20. The amplitudes and the relaxation time of overpopulation in the ''cupola'' region of distribution are substantially lower than in the case of a developed effect in the tail. The influence of the effect on the kinetics of threshold chemical reaction is studied. From the results it follows that in the process of nonmonotone relaxation the mean rates of binary threshold reactions can exceed more than twice the equilibrium values. This estimate is valid for all power like intermolecular repulsive potentials from the pseudo-Maxwell model up to rigid spheres. Time intervals over which the mean reaction rate exceeds considerably the equilibrium one make from 5 to 15 mean free path times increasing with the decrease in the potential ''rigidity''. (author)

Relaxation effect of marmin on guinea pig tracheal smooth muscle via NO-independent mechanisms

Directory of Open Access Journals (Sweden)

Dadang Irfan Husori

2012-05-01

Full Text Available Objective: To investigate the relaxation mechanims of marmin on epithelium of guinea pig isolated trachea smooth muscle (TSM. Methods: The study was conducted using in vitro isolated-trachea experimental. The guinea pig isolated trachea were incubated in Krebs solution-containing organ bath and supplied with a mixed gas of O2:CO2 (95%:5%. Result: Removal of tracheal epithelium was associated with significant increases in the potencies of histamine and methacholine to contract guinea pig TSM. The pD2 value of histamine increased from 6.04依0.08 on epithelial-intact to 6.32依0.06 on epithelial-denuded (P<0.05. The pD2 value of methacholine also increased from 5.85依0.09 on epithelial-intact to 6.15依0.07 on epithelial-denuded (P<0.05. Marmin exhibited relaxation effects on TSM induced by methacholine (3伊10-5 mol/L and histamine (3伊10-5 mol/L. Inhibition of prostaglandin E2 (PGE2 through incubation with indomethacin could reduce the relaxation effect of marmin (P<0.05 on methacholine- and histamine-induced contractions. However, no significant differenceswere shown in methylene blue, Nω-nitro-L-arginine (L-NNA and propranolol-incubated TSM. Conclusions: The results suggest that marmin has relaxation effect on TSM which is epithelial-dependent through the release of PGE2. However, nitric oxide, cGMP and 毬 2-adrenergic-mediated relaxation were not involved.

An investigation into the effects of pore connectivity on T2 NMR relaxation

Science.gov (United States)

Ghomeshi, Shahin; Kryuchkov, Sergey; Kantzas, Apostolos

2018-04-01

Nuclear Magnetic Resonance (NMR) is a powerful technique used to characterize fluids and flow in porous media. The NMR relaxation curves are closely related to pore geometry, and the inversion of the NMR relaxometry data is known to give useful information with regards to pore size distribution (PSD) through the relative amplitudes of the fluids stored in the small and large pores. While this information is crucial, the main challenge for the successful use of the NMR measurements is the proper interpretation of the measured signals. Natural porous media patterns consist of complex pore structures with many interconnected or "coupled" regions, as well as isolated pores. This connectivity along the throats changes the relaxation distribution and in order to properly interpret this data, a thorough understanding of the effects of pore connectivity on the NMR relaxation distribution is warranted. In this paper we address two main points. The first pertains to the fact that there is a discrepancy between the relaxation distribution obtained from experiments, and the ones obtained from solving the mathematical models of diffusion process in the digitized images of the pore space. There are several reasons that may attribute to this such as the lack of a proper incorporation of surface roughness into the model. However, here we are more interested in the effects of pore connectivity and to understand why the typical NMR relaxation distribution obtained from experiments are wider, while the numerical simulations predict that a wider NMR relaxation distribution may indicate poor connectivity. Secondly, by not taking into account the pore coupling effects, from our experience in interpreting the data, we tend to underestimate the pore volume of small pores and overestimate the amplitudes in the large pores. The role of pore coupling becomes even more prominent in rocks with small pore sizes such as for example in shales, clay in sandstones, and in the microstructures of

Composition effect of potassium-borate glasses on their relaxation properties

International Nuclear Information System (INIS)

Lomovskoj, V.A.; Bartenev, G.M.

1995-01-01

Relaxation processes in potassium-borate glasses have been investigated in detail for the first time. It is shown that low-temperature β-process of relaxation relating to rotational mobility of the B-O bond is the same for all potassium-borate glasses and B 2 O 3 . The process of β k -relaxation related to diffusion mobility of potassium ions depends on the composition of the glasses in the same way as α-relaxation (glass formation).12 refs., 10 figs., 2 tabs

Effect of carrier relaxation lifetime on the performance of InAs/InP quantum-dash lasers

KAUST Repository

Khan, Mohammed Zahed Mustafa

2011-12-01

The effect of carrier relaxation process into the quantum dash (Qdash) ground state (GS) is examined theoretically by carrier-photon rate equation model incorporating the inhomogeneous broadening. Increase in the relaxation time and the inhomogeneous broadening degrades the threshold current density. Moreover, our results show that a relaxation time of less than 2 ps gives optimum laser performance. © 2011 IEEE.

Relaxant effect of ghrelin on guinea pig isolated tracheal smooth muscle: role of epithelial NO and PGE2.

Science.gov (United States)

Al-Ayed, Mohammed Saeed Zayed

2018-06-01

This study aimed at investigating the potential ghrelin relaxing effect on guinea pig isolated tracheal smooth muscle (TSM). Using an in vitro experimental approach, the physiological role of the airway epithelium on smooth muscle relaxation has been investigated by analyzing the dose-response curves for carbachol- or histamine-induced contractions on epithelium intact versus denuded tracheal tissue. The relaxant effect of ghrelin (5-200 μmol/L) then investigated on carbachol-contracted, non-sensitized, and ovalbumin (OVA)-sensitized guinea pig TSM with an intact or denuded epithelium. The isolated TSMs from identical guinea pigs were incubated in Krebs solution aerated with 95% O 2 and 5% CO 2 through an automated tissue organ bath system (n = 6 for each group). The ghrelin relaxation mechanism was assessed by adding L-NAME, indomethacin, and YIL-781 for GHS-R1 into the tissue chamber. The spasmogens carbachol and histamine have shown a significantly higher contracting effect on epithelium-denuded than in epithelium-intact TSM confirmed by the significantly higher mean pEC50 of both agonists on the epithelium-denuded trachea (p < 0.05). Ghrelin has shown a concentration-dependent relaxing effect on carbachol-contracted TSM (r = 0.96, p = 0.00). The effect was more evident in the intact non-sensitized than in epithelium-denuded or OVA-sensitized groups (p < 0.05). Preincubation with nitric oxide (NO) and prostaglandin E 2 (PGE 2 ) inhibitors has significantly reduced the ghrelin-induced relaxation on epithelium-intact TSM suggesting an epithelium-dependant mechanism. However, GHS-R1a antagonist has also succeeded to reduce ghrelin relaxant effect, which needs further clarification. Ghrelin proved to have a potential TSM relaxant effect possibly through epithelium-dependant mechanisms involving NO and PGE 2 .

The Effect Of Motivational And Relaxation Music On Aerobic ...

African Journals Online (AJOL)

The purpose of this study was to examine the effect of motivational and relaxation music on aerobic performance, rating of perceived exertion (RPE) and salivary cortisol (SC) concentration in trained men. Thirty male physical education college students (ages: 25.66±3.89 yr, height: 176.65±7.66 cm, weight: 78.45±16.20 kg, ...

Post-CHF heat transfer: a non-equilibrium, relaxation model

International Nuclear Information System (INIS)

Jones, O.C. Jr.; Zuber, N.

1977-01-01

Existing phenomenological models of heat transfer in the non-equilibrium, liquid-deficient, dispersed flow regime can sometimes predict the thermal behavior fairly well but are quite complex, requiring coupled simultaneous differential equations to describe the axial gradients of mass and energy along with those of droplet acceleration and size. In addition, empirical relations are required to express the droplet breakup and increased effective heat transfer due to holdup. This report describes the development of a different approach to the problem. It is shown that the non-equilibrium component of the total energy can be expressed as a first order, inhomogeneous relaxation equation in terms of one variable coefficient termed the Superheat Relaxation number. A demonstration is provided to show that this relaxation number can be correlated using local variables in such a manner to allow the single non-equilibrium equation to accurately calculate the effects of mass velocity and heat flux along with tube length, diameter, and critical quality for equilibrium qualities from 0.13 to over 3.0

The effects of some parameters on the calculated 1H NMR relaxation times of cell water

International Nuclear Information System (INIS)

Koivula, A.; Suominen, K.; Kiviniitty, K.

1976-01-01

The effect of some parameters on the longitudinal and transverse relaxation times is calculated and a comparison between the calculated relaxation times with the results of different measurements is made. (M.S.)

Peroxynitrite-induced relaxation in isolated rat aortic rings and mechanisms of action

International Nuclear Information System (INIS)

Li Jianfeng; Li Wenyan; Altura, Bella T.; Altura, Burton M.

2005-01-01

The present study was designed to evaluate the effects of peroxynitrite (ONOO - ), the product of superoxide and nitric oxide, on isolated segments of rat aorta. In the absence of any vasoactive agent, ONOO - (from 10 -8 to 10 -4 M) failed to alter the basal tension. In phenylephrine (PE; 5 x 10 -7 M)-precontracted rat aortic rings (RAR), ONOO - elicited concentration-dependent relaxation at concentrations of from 10 -8 to 10 -4 M. The effective concentrations producing approximately 50% of maximal relaxation (ED 5 ) to ONOO - were 1.84 x 10 -5 M and 1.96 x 10 -5 M in intact and denuded RAR, respectively (P > 0.05). No significant differences in the relaxation responses were found between RAR with or without endothelium (P > 0.05). The presence of either 5 μM methylene blue (MB) or 5 μM 1H-[1,2,4]oxadiazolo-[4,3-α]quinoxalin-1-one (ODQ) significantly inhibited the relaxations induced by ONOO - . Sildenafil (10 -7 M), on the other hand, significantly potentiated the ONOO - -induced relaxations. Tetraethylammonium chloride (T-2265) significantly decreased the ONOO - -induced relaxations in a concentration-dependent manner. However, ONOO - had no effect on RAR precontracted by high KCL (40 mM, n = 6, P > 0.05). Addition of calyculin A also significantly decreased the ONOO - -induced relaxation in a dose-dependent manner. Furthermore, ONOO - significantly inhibited calcium-induced contractions of K + -depolarized aortic rings in a concentration-related manner. Lastly, a variety of other pharmacological agents and antagonists including L-NMMA, L-arginine, indomethacin, atropine, naloxone, diphenhydramine, cimetine, glibenclamide, haloperidol, superoxide dismutase (SOD), and catalase did not influence the relaxant effects of ONOO - on RAR. Our new results suggest that ONOO - -triggered relaxation on rat aortic rings is mediated by elevation of cGMP levels, membrane hyperpolarization via K + -channel activation, activation of myosin phosphatase activity, and

“Remain calm. Be kind”: Effects of relaxing video games on aggressive and prosocial behavior

NARCIS (Netherlands)

Whitaker, J.L.; Bushman, B.J.

2012-01-01

Research shows that violent video games increase aggressive behavior and decrease prosocial behavior, but could relaxing video games have the opposite effects? In two experiments, participants were randomly assigned to play a relaxing, neutral, or prosocial video game for 20 min. In Experiment 1,

Large lateral photovoltaic effect with ultrafast relaxation time in SnSe/Si junction

Energy Technology Data Exchange (ETDEWEB)

Wang, Xianjie; Zhao, Xiaofeng; Hu, Chang; Zhang, Yang; Song, Bingqian; Zhang, Lingli; Liu, Weilong; Lv, Zhe; Zhang, Yu; Sui, Yu, E-mail: suiyu@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Tang, Jinke [Department of Physics and Astronomy, University of Wyoming, Laramie, Wyoming 82071 (United States); Song, Bo, E-mail: songbo@hit.edu.cn [Department of Physics, Harbin Institute of Technology, Harbin 150001 (China); Academy of Fundamental and Interdisciplinary Sciences, Harbin Institute of Technology, Harbin 150001 (China)

2016-07-11

In this paper, we report a large lateral photovoltaic effect (LPE) with ultrafast relaxation time in SnSe/p-Si junctions. The LPE shows a linear dependence on the position of the laser spot, and the position sensitivity is as high as 250 mV mm{sup −1}. The optical response time and the relaxation time of the LPE are about 100 ns and 2 μs, respectively. The current-voltage curve on the surface of the SnSe film indicates the formation of an inversion layer at the SnSe/p-Si interface. Our results clearly suggest that most of the excited-electrons diffuse laterally in the inversion layer at the SnSe/p-Si interface, which results in a large LPE with ultrafast relaxation time. The high positional sensitivity and ultrafast relaxation time of the LPE make the SnSe/p-Si junction a promising candidate for a wide range of optoelectronic applications.

Mozart versus new age music: relaxation states, stress, and ABC relaxation theory.

Science.gov (United States)

Smith, Jonathan C; Joyce, Carol A

2004-01-01

New Age music or read popular recreational magazines. Results suggest the usefulness of ABC relaxation theory in comparing the different effects of music and relaxation techniques.

Near-threshold photoionization of the Xe 3d spin-orbit doublet: Relativistic, relaxation, and intershell interaction effects

International Nuclear Information System (INIS)

Radojevic, V.; Davidovic, D.M.; Amusia, M.Ya.

2003-01-01

Results of calculations of the near-threshold photoionization of the xenon 3d spin-orbit doublet are reported. Our theoretical analysis is undertaken in order to interpret and enlighten the very detailed measurements of this process [A. Kivimaeki et al., Phys. Rev. A 63, 012716 (2001)], which revealed a previously unobserved interesting feature--an additional broad maximum--in the partial xenon 3d 5/2 cross section. This double maximum was not produced by earlier calculations, except in the recent study by Amusia et al. [Phys. Rev. Lett. 88, 093002 (2002)], which, in contrast to the present one, is not ab initio and relativistic in character. The partial photoionization cross sections of 3d 5/2 and 3d 3/2 subshells, photoelectron anisotropy parameters, and spin-polarization parameters that were so far not studied either experimentally or theoretically are calculated. Many-electron correlations, relativistic effects, and relaxation effects of the ionic core in the ionization process are taken into account by using the relativistic random-phase approximation, modified to include the relaxation of the considered subshell

Stress relaxation under cyclic electron irradiation

International Nuclear Information System (INIS)

Bystrov, L.N.; Reznitskij, M.E.

1990-01-01

The kinetics of deformation process in a relaxating sample under 2 MeV electron cyclic irradiation was studied experimentally. The Al-Mg alloys with controllable and different (in dislocation density precipitate presence and their character) structure were used in experiments. It was established that after the beam was switched on the deformation rate increased sharply and then, during prolonged irradiation, in a gradual manner. After the switching-off the relaxation rate decreases by jumps up to values close to extrapolated rates of pre-radiation relaxation. The exhibition of these effects with radiation switching-off and switchin-on is dependent on the initial rate of thermal relaxation, the test temperature, the preliminary cold deformation and the dominating deformation dislocation mechanism. The preliminary cold deformation and test temperature elevation slightly decrease the effect of instantaneous relaxation acceleration with the irradiation switch-on. 17 refs., 5 figs

The effect of body-mind relaxation meditation induction on major depressive disorder: A resting-state fMRI study.

Science.gov (United States)

Chen, Fangfang; Lv, Xueyu; Fang, Jiliang; Yu, Shan; Sui, Jing; Fan, Lingzhong; Li, Tao; Hong, Yang; Wang, XiaoLing; Wang, Weidong; Jiang, Tianzi

2015-09-01

Meditation has been increasingly evaluated as an important complementary therapeutic tool for the treatment of depression. The present study employed resting-state functional magnetic resonance imaging (rs-fMRI) to examine the effect of body-mind relaxation meditation induction (BMRMI) on the brain activity of depressed patients and to investigate possible mechanisms of action for this complex intervention. 21 major depressive disorder patients (MDDs) and 24 age and gender-matched healthy controls (HCs) received rs-fMRI scans at baseline and after listening to a selection of audio designed to induce body-mind relaxation meditation. The rs-fMRI data were analyzed using Matlab toolbox to obtain the amplitude of low-frequency fluctuations (ALFF) of the BOLD signal for the whole brain. A mixed-design repeated measures analysis of variance (ANOVA) was performed on the whole brain to find which brain regions were affected by the BMRMI. An additional functional connectivity analysis was used to identify any atypical connection patterns after the BMRMI. After the BMRMI experience, both the MDDs and HCs showed decreased ALFF values in the bilateral frontal pole (BA10). Additionally, increased functional connectivity from the right dorsal medial prefrontal cortex (dmPFC) to the left dorsal lateral prefrontal cortex (dlPFC) and the left lateral orbitofrontal cortex (OFC) was identified only in the MDDs after the BMRMI. In order to exclude the impact of other events on the participants׳ brain activity, the Hamilton Rating Scales for Depression (HDRS) was not measured after the body-mind relaxation induction. Our findings support the hypothesis that body-mind relaxation meditation induction may regulate the activities of the prefrontal cortex and thus may have the potential to help patients construct reappraisal strategies that can modulate the brain activity in multiple emotion-processing systems. Copyright © 2015 Elsevier B.V. All rights reserved.

Comparing the effects of reflexology and relaxation on fatigue in women with multiple sclerosis.

Science.gov (United States)

Nazari, Fatemeh; Shahreza, Mozhgan Soheili; Shaygannejad, Vahid; Valiani, Mahboubeh

2015-01-01

Fatigue is the most common and highly disabling symptom of multiple sclerosis (MS) that has negative effects on employment, the process of socialization, compliance with the disease, and other factors effective on activities of daily living. The usage of complementary and alternative medicine methods in MS patients is higher than in the general population. However, there is no scientific evidence to support their effectiveness. Therefore, this study aimed to compare the effects of reflexology and relaxation on fatigue in women with MS. This study is a single-blinded randomized clinical trial that was done on 75 patients with MS who referred to the MS Clinic of Ayatollah Kashani Hospital (Isfahan, Iran). After simple non-random sampling, participants were randomly assigned by minimization method to three groups: Reflexology, relaxation, and control groups (25 patients in each group). In the experimental groups, the interventions foot reflexology and relaxation (Jacobson and Benson) were performed for 4 weeks, twice a week for 40 min in each session, and the control group received care and routine medical treatment as directed by a physician. Data were collected through a questionnaire and the fatigue severity scale before, immediately after, and 2 months after interventions from all three groups. Data analysis was performed by SPSS version 18 using descriptive and inferential statistical methods. Findings obtained from analysis of variance (ANOVA) showed that there was no significant difference in the mean fatigue severity scores in the pre-interventions between the three groups (P > 0.05), but there was significant difference immediately after and 2 months after interventions between the three groups (P 0.05). Furthermore, least significant difference post-hoc test revealed that the mean scores of fatigue severity immediately after intervention was lower in the reflexology group than in the other two groups and were lower in the relaxation group than in the control

The Efficacy of Relaxation Training in Treating Anxiety

Science.gov (United States)

Francesco, Pagnini; Mauro, Manzoni Gian; Gianluca, Castelnuovo; Enrico, Molinari

2009-01-01

This paper provides a review of scientific literature about relaxation training and its effects on anxiety. Research investigating progressive relaxation, meditation, applied relaxation and autogenic training were considered. All these methods proved to be effective in reducing anxiety in all kind of samples, affected or not by physical or…

Electron spin relaxation in a transition-metal dichalcogenide quantum dot

Science.gov (United States)

Pearce, Alexander J.; Burkard, Guido

2017-06-01

We study the relaxation of a single electron spin in a circular quantum dot in a transition-metal dichalcogenide monolayer defined by electrostatic gating. Transition-metal dichalcogenides provide an interesting and promising arena for quantum dot nano-structures due to the combination of a band gap, spin-valley physics and strong spin-orbit coupling. First we will discuss which bound state solutions in different B-field regimes can be used as the basis for qubits states. We find that at low B-fields combined spin-valley Kramers qubits to be suitable, while at large magnetic fields pure spin or valley qubits can be envisioned. Then we present a discussion of the relaxation of a single electron spin mediated by electron-phonon interaction via various different relaxation channels. In the low B-field regime we consider the spin-valley Kramers qubits and include impurity mediated valley mixing which will arise in disordered quantum dots. Rashba spin-orbit admixture mechanisms allow for relaxation by in-plane phonons either via the deformation potential or by piezoelectric coupling, additionally direct spin-phonon mechanisms involving out-of-plane phonons give rise to relaxation. We find that the relaxation rates scale as \\propto B 6 for both in-plane phonons coupling via deformation potential and the piezoelectric effect, while relaxation due to the direct spin-phonon coupling scales independant to B-field to lowest order but depends strongly on device mechanical tension. We will also discuss the relaxation mechanisms for pure spin or valley qubits formed in the large B-field regime.

Effect of pressure on the α relaxation in glycerol and xylitol

Science.gov (United States)

Paluch, M.; Casalini, R.; Hensel-Bielowka, S.; Roland, C. M.

2002-06-01

The effect of pressure on the dielectric relaxation of two polyhydroxy alcohols is examined by analysis of existing data on glycerol, together with new measurements on xylitol. The fragility, or Tg-normalized temperature dependence, changes with pressure for low pressures, but becomes invariant above 1 GPa. When compared at temperatures for which the α-relaxation times are equal, there is no effect of pressure (xylitol show an excess intensity at higher frequencies. For xylitol, unlike for glycerol, at lower temperatures this wing disjoins to form a separate peak. For both glass formers, elevated pressure causes the excess wing to become more separated from the peak maximum; that is, the properties of the primary and excess intensities are not correlated. This implies that the excess wing in glycerol is also a distinct secondary process, although it cannot be resolved from the primary peak.

Rotation and scale change invariant point pattern relaxation matching by the Hopfield neural network

Science.gov (United States)

Sang, Nong; Zhang, Tianxu

1997-12-01

Relaxation matching is one of the most relevant methods for image matching. The original relaxation matching technique using point patterns is sensitive to rotations and scale changes. We improve the original point pattern relaxation matching technique to be invariant to rotations and scale changes. A method that makes the Hopfield neural network perform this matching process is discussed. An advantage of this is that the relaxation matching process can be performed in real time with the neural network's massively parallel capability to process information. Experimental results with large simulated images demonstrate the effectiveness and feasibility of the method to perform point patten relaxation matching invariant to rotations and scale changes and the method to perform this matching by the Hopfield neural network. In addition, we show that the method presented can be tolerant to small random error.

The effects of Chinese calligraphy handwriting and relaxation training in Chinese Nasopharyngeal Carcinoma patients: a randomized controlled trial.

Science.gov (United States)

Yang, Xue-Ling; Li, Huan-Huan; Hong, Ming-Huang; Kao, Henry S R

2010-05-01

Chinese calligraphy handwriting is the practice of traditional Chinese brush writing, researches found calligraphy had therapeutic effects on certain diseases, some authors argued that calligraphy might have relaxation effect. This study was to compare the effects of calligraphy handwriting with those of progressive muscle relaxation and imagery training in Chinese Nasopharyngeal Carcinoma patients. This study was a randomized controlled trial. Two hundred and eighty-seven Nasopharyngeal Carcinoma patients were approached, ninety (31%) patients were recruited and randomized to one of the three treatment groups: progressive muscle relaxation and guided imagery training group, Calligraphy handwriting group, or a Control group. Seventy-nine (87.8%) completed all of the outcome measures. The primary treatment outcome was the changes of physiological arousal parameters measured by pre- and post-treatment differences of heart rate, blood pressure and respiration rate. The secondary outcomes included: modified Chinese version of Symptom Distress Scale, Profile of Mood State-Short Form, and Karnofsky Performance Status measured at baseline, during treatment (after the 2-week intervention), post-treatment (after the 4-week intervention) and after a 2-week follow-up. Effectiveness was tested by repeated measure ANOVA analyses. Cancer centre of a major university hospital in Guangdong, China. Results showed that both of calligraphy and relaxation training demonstrated slow-down effects on physiological arousal parameters. Moreover, calligraphy practice gradually lowered participants' systolic blood pressure (simple main effect of time at pre-treatment measure, p=.007) and respiration rate (p=.000) at pre- and post-treatment measures as the intervention proceeded, though with a smaller effect size as compared to relaxation. Both of calligraphy and relaxation training had certain symptom relief and mood improvement effects in NPC patients. Relaxation was effective in relieving

Effect of the growth conditions on the anisotropy, domain structures and the relaxation in Co thin films

Energy Technology Data Exchange (ETDEWEB)

Mallik, Srijani; Mallick, Sougata; Bedanta, Subhankar, E-mail: sbedanta@niser.ac.in

2017-04-15

We report a systematic study on the anisotropy symmetry, magnetic domains and magnetic relaxation behavior in Co thin films deposited on MgO (001) substrate by varying (i) the pre-annealing condition and (ii) the speed of substrate rotation during deposition. Substrate annealing prior to deposition leads to the formation of textured thin films. On contrary Co films prepared without substrate pre-annealing exhibit polycrystalline nature. Surface topography imaged by atomic force microscopy (AFM) depicts a profound effect of growth condition on grain size and its distribution. Magnetic hysteresis measurement along with simultaneous domain imaging has been performed by magneto optic Kerr effect (MOKE) based microscope by varying the angle (ϕ) between the easy axis and the direction of applied magnetic field. We observed the existence of cubic and uniaxial anisotropy due to the presence of substrate annealing and oblique angular deposition, respectively. Along the easy axis, magnetization reversal is governed by 180° domain wall motion via branched domains. However, for easy axis<ϕaddition to branched domains during the reversal process. We observed that the magnetic relaxation behavior under constant magnetic field strongly depends on the size and distribution of the grains. - Highlights: • This article provides a systematic study of textured growth of Co on MgO(001) substrate. • The structure has clear implication on the magnetic properties. • The magnetic relaxation has been studied for both textured and polycrystalline films.

Effects of Energy Relaxation via Quantum Coupling Among Three-Dimensional Motion on the Tunneling Current of Graphene Field-Effect Transistors.

Science.gov (United States)

Mao, Ling-Feng; Ning, Huansheng; Li, Xijun

2015-12-01

We report theoretical study of the effects of energy relaxation on the tunneling current through the oxide layer of a two-dimensional graphene field-effect transistor. In the channel, when three-dimensional electron thermal motion is considered in the Schrödinger equation, the gate leakage current at a given oxide field largely increases with the channel electric field, electron mobility, and energy relaxation time of electrons. Such an increase can be especially significant when the channel electric field is larger than 1 kV/cm. Numerical calculations show that the relative increment of the tunneling current through the gate oxide will decrease with increasing the thickness of oxide layer when the oxide is a few nanometers thick. This highlights that energy relaxation effect needs to be considered in modeling graphene transistors.

Substituent effects on the relaxation dynamics of furan, furfural and β-furfural: a combined theoretical and experimental approach.

Science.gov (United States)

Oesterling, Sven; Schalk, Oliver; Geng, Ting; Thomas, Richard D; Hansson, Tony; de Vivie-Riedle, Regina

2017-01-18

For the series furan, furfural and β-furfural we investigated the effect of substituents and their positioning on the photoinduced relaxation dynamics in a combined theoretical and experimental approach. Using time resolved photoelectron spectroscopy with a high intensity probe pulse, we can, for the first time, follow the whole deactivation process of furan through a two photon probe signal. Using the extended 2-electron 2-orbital model [Nenov et al., J. Chem. Phys., 2011, 135, 034304] we explain the formation of one central conical intersection and predict the influence of the aldehyde group of the derivatives on its geometry. This, as well as the relaxation mechanisms from photoexcitation to the final outcome was investigated using a variety of theoretical methods. Complete active space self consistent field was used for on-the-fly calculations while complete active space perturbation theory and coupled cluster theory were used to accurately describe critical configurations. Experiment and theory show the relaxation dynamics of furfural and β-furfural to be slowed down, and together they disclose an additional deactivation pathway, which is attributed to the n O lonepair state introduced with the aldehyde group.

Spin-lattice relaxation of individual solid-state spins

Science.gov (United States)

Norambuena, A.; Muñoz, E.; Dinani, H. T.; Jarmola, A.; Maletinsky, P.; Budker, D.; Maze, J. R.

2018-03-01

Understanding the effect of vibrations on the relaxation process of individual spins is crucial for implementing nanosystems for quantum information and quantum metrology applications. In this work, we present a theoretical microscopic model to describe the spin-lattice relaxation of individual electronic spins associated to negatively charged nitrogen-vacancy centers in diamond, although our results can be extended to other spin-boson systems. Starting from a general spin-lattice interaction Hamiltonian, we provide a detailed description and solution of the quantum master equation of an electronic spin-one system coupled to a phononic bath in thermal equilibrium. Special attention is given to the dynamics of one-phonon processes below 1 K where our results agree with recent experimental findings and analytically describe the temperature and magnetic-field scaling. At higher temperatures, linear and second-order terms in the interaction Hamiltonian are considered and the temperature scaling is discussed for acoustic and quasilocalized phonons when appropriate. Our results, in addition to confirming a T5 temperature dependence of the longitudinal relaxation rate at higher temperatures, in agreement with experimental observations, provide a theoretical background for modeling the spin-lattice relaxation at a wide range of temperatures where different temperature scalings might be expected.

A randomized controlled trial to determine the effects of music and relaxation interventions on perceived anxiety in hospitalized patients receiving orthopaedic or cancer treatment.

Science.gov (United States)

Eckhouse, Diane R; Hurd, Mary; Cotter-Schaufele, Susan; Sulo, Suela; Sokolowski, Malgorzata; Barbour, Laurel

2014-01-01

Nonpharmacological interventions, including combinations of music, education, coping skills, and relaxation techniques, have been found to have a positive effect on patients' perceived anxiety in many settings. However, few research studies have assessed and compared the effectiveness of music and relaxation interventions in reducing the anxiety levels of orthopaedic and oncology patients. We conducted a prospective, randomized, controlled study to examine the effectiveness of music and relaxation interventions on perceived anxiety during initial hospitalization for patients receiving orthopaedic or cancer care treatment at a Midwestern teaching hospital. This was a pre-test/post-test study design utilizing the State-Trait Anxiety Inventory. One hundred twelve patients were randomized into 3 study groups. Thirty-eight subjects (34%) were randomized in the music-focused relaxation group, 35 subjects (31%) in the music and video group, and 39 (35%) subjects in the control group. Fifty-seven (51%) were orthopaedic patients and 55 (49%) were oncology patients. Comparison of the 3 study groups showed no statistically significant differences with regard to patients' demographics. Although reduced anxiety levels were reported for all 3 groups postintervention, the differences were not statistically significant (p > .05). Also, there was no significant difference found between the perceived anxiety levels of patients admitted to the orthopaedic and oncology care units (p > .05). Finally, the results of the intragroup comparisons (regardless of the group assignment) showed a significant decrease in anxiety levels reported by all patients postintervention (p Music and relaxation interventions could be an additional tool in assisting patients to become less anxious during their hospital stay. Music focused relaxation and music and video are both valuable and cost-effective strategies that can assist the orthopaedic and oncology patient population. Identifying opportunities to

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels

International Nuclear Information System (INIS)

Roberts, R.E.; Allen, S.; Chang, A.P.Y.; Henderson, H.; Hobson, G.C.; Karania, B.; Morgan, K.N.; Pek, A.S.Y.; Raghvani, K.; Shee, C.Y.; Shikotra, J.; Street, E.; Abbas, Z.; Ellis, K.; Heer, J.K.; Alexander, S.P.H.

2013-01-01

German chamomile (Matricaria recutita L.), a widely-used herbal medicine, has been reported to have a wide range of biological effects, including smooth muscle relaxation. The aim of this study was to compare the effects of representative compounds from chamomile (apigenin, luteolin, (−)-α-bisabolol, farnesene, umbelliferone; 3–30 μM) on vascular tone using porcine coronary and splenic arteries mounted for isometric tension recording in isolated tissue baths and precontracted with the thromboxane-mimetic U46619. Apigenin, luteolin, and (−)-α-bisabolol produced slow, concentration-dependent relaxations in both the coronary and splenic arteries that were not blocked by inhibition of nitric oxide synthase or potassium channels. Removal of extracellular calcium inhibited the relaxations to all three compounds, and these compounds also inhibited calcium re-addition-evoked contractions, indicating that the relaxation response may be mediated through inhibition of calcium influx. Apigenin and luteolin, but not (−)-α-bisabolol, enhanced the relaxation to the nitric oxide donor sodium nitroprusside, indicating that apigenin and luteolin may act to regulate cyclic GMP levels. Umbelliferone produced a rapid, transient relaxation in the splenic artery, but not the coronary artery, that was inhibited by L-NAME and removal of the endothelium, suggesting an influence on nitric oxide production. Farnesene, at concentrations up to 30 μM, was without effect in either blood vessel. In conclusion, hydroxylated compounds (apigenin, luteolin and (−)-α-bisabolol) found in chamomile all caused a slow relaxation of isolated blood vessels through an effect on calcium influx. Umbelliferone, on the other hand, produced a rapid, transient relaxation dependent upon release of nitric oxide from the endothelium. - Highlights: • Apigenin, luteolin, and (-)-α-bisabolol are present in chamomile. • They produced slow, concentration-dependent relaxations in arteries. • These

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels

Energy Technology Data Exchange (ETDEWEB)

Roberts, R.E., E-mail: Richard.roberts@nottingham.ac.uk; Allen, S.; Chang, A.P.Y.; Henderson, H.; Hobson, G.C.; Karania, B.; Morgan, K.N.; Pek, A.S.Y.; Raghvani, K.; Shee, C.Y.; Shikotra, J.; Street, E.; Abbas, Z.; Ellis, K.; Heer, J.K.; Alexander, S.P.H., E-mail: steve.alexander@nottingham.ac.uk

2013-11-01

German chamomile (Matricaria recutita L.), a widely-used herbal medicine, has been reported to have a wide range of biological effects, including smooth muscle relaxation. The aim of this study was to compare the effects of representative compounds from chamomile (apigenin, luteolin, (−)-α-bisabolol, farnesene, umbelliferone; 3–30 μM) on vascular tone using porcine coronary and splenic arteries mounted for isometric tension recording in isolated tissue baths and precontracted with the thromboxane-mimetic U46619. Apigenin, luteolin, and (−)-α-bisabolol produced slow, concentration-dependent relaxations in both the coronary and splenic arteries that were not blocked by inhibition of nitric oxide synthase or potassium channels. Removal of extracellular calcium inhibited the relaxations to all three compounds, and these compounds also inhibited calcium re-addition-evoked contractions, indicating that the relaxation response may be mediated through inhibition of calcium influx. Apigenin and luteolin, but not (−)-α-bisabolol, enhanced the relaxation to the nitric oxide donor sodium nitroprusside, indicating that apigenin and luteolin may act to regulate cyclic GMP levels. Umbelliferone produced a rapid, transient relaxation in the splenic artery, but not the coronary artery, that was inhibited by L-NAME and removal of the endothelium, suggesting an influence on nitric oxide production. Farnesene, at concentrations up to 30 μM, was without effect in either blood vessel. In conclusion, hydroxylated compounds (apigenin, luteolin and (−)-α-bisabolol) found in chamomile all caused a slow relaxation of isolated blood vessels through an effect on calcium influx. Umbelliferone, on the other hand, produced a rapid, transient relaxation dependent upon release of nitric oxide from the endothelium. - Highlights: • Apigenin, luteolin, and (-)-α-bisabolol are present in chamomile. • They produced slow, concentration-dependent relaxations in arteries. • These

Effects of irradiation temperature on polarisation and relaxation characteristics of polymeric materials

Energy Technology Data Exchange (ETDEWEB)

Bornstein, Marcel; Dutz, Hartmut; Goertz, Stefan; Reeve, Scott; Runkel, Stefan [Physikalisches Institut, Bonn Univ. (Germany)

2016-07-01

To achieve significant enhancement of polarisation of solid target materials one must use the principles of dynamic nuclear polarisation and utilise the coupling of the nuclear and electron spins. The unpaired electrons needed can be created as paramagnetic structural defects by irradiation of the material. Polyethylene and polypropylene materials were irradiated at various temperatures and subsequently polarised with microwaves of approximately 70 GHz at temperatures around 1 K. Additionally the samples were investigated with respect to the nature of the created paramagnetic defects using a X-band EPR spectrometer. It was found that the irradiation temperature has a significant effect on the polarisation values achieved and also on the relaxation times of the materials in the 2.5 T magnetic field. The EPR line shape is clearly dominated by the well known alkyl radical structure.

Le Chatelier's principle with multiple relaxation channels

Science.gov (United States)

Gilmore, R.; Levine, R. D.

1986-05-01

Le Chatelier's principle is discussed within the constrained variational approach to thermodynamics. The formulation is general enough to encompass systems not in thermal (or chemical) equilibrium. Particular attention is given to systems with multiple constraints which can be relaxed. The moderation of the initial perturbation increases as additional constraints are removed. This result is studied in particular when the (coupled) relaxation channels have widely different time scales. A series of inequalities is derived which describes the successive moderation as each successive relaxation channel opens up. These inequalities are interpreted within the metric-geometry representation of thermodynamics.

Evidence of direct smooth muscle relaxant effects of the fibrate gemfibrozil.

Science.gov (United States)

Phelps, Laura E; Peuler, Jacob D

2010-01-01

Fibrates are commonly employed to treat abnormal lipid metabolism via their unique ability to stimulate peroxisome proliferator-activated receptor alpha (PPARalpha). Interestingly, they also decrease systemic arterial pressure, despite recent evidence that PPAR alpha may contribute to expression of renin and related hypertension. Yet, mechanisms responsible for their potential antihypertensive activity remain unresolved. Rapid decreases in arterial pressure following bolus intravenous injections of bezafibrate strongly suggest they may relax arterial smooth muscle directly. But since bezafibrate is highly susceptible to photodegradation in aqueous media, it has never been critically tested for this possibility in vitro with isolated arterial smooth muscle preparations. Accordingly, we tested gemfibrozil which is resistant to photodegradation. We examined it over a therapeutically-relevant range (50-400 microM) for both acute and delayed relaxant effects on contractions of the isolated rat tail artery; contractions induced by either depolarizing its smooth muscle cell membranes with high potassium or stimulating its membrane-bound receptors with norepinephrine and arginine-vasopressin. We also examined these same gemfibrozil levels for effects on spontaneously-occurring phasic rhythmic contractile activity, typically not seen in arteries under in vitro conditions but commonly exhibited by smooth muscle of uterus, duodenum and bladder. We found that gemfibrozil significantly relaxed all induced forms of contraction in the rat tail artery, acutely at the higher test levels and after a delay of a few hours at the lower test levels. The highest test level of gemfibrozil (400 microM) also completely abolished spontaneously-occurring contractile activity of the isolated uterus and duodenum and markedly suppressed it in the bladder. This is the first evidence that a fibrate drug can directly relax smooth muscle contractions, either induced by various contractile agents or

The structural relaxation effect on the nanomechanical properties of a Ti-based bulk metallic glass

International Nuclear Information System (INIS)

Huang, Yongjiang; Zhou, Binjun; Chiu, YuLung; Fan, Hongbo; Wang, Dongjun; Sun, Jianfei; Shen, Jun

2014-01-01

Highlights: • The effect of structural relaxation on the nano-mechanical behaviors of BMGs is studied. • The indent load at first pop-in event, the hardness and Young’s modulus are enhanced after annealing. • The differences in nanomechanical properties can be attributed to their different atomic structure. - Abstract: Indentation experiments were performed on the as-cast and the annealed Ti-based bulk metallic glass samples to investigate the effect of structural relaxation on the nanomechanical behaviors of the material. The onset of pop-in event, Young’s modulus, and hardness were found to be sensitive to the structural relaxation of the testing material. The difference in nanomechanical properties between the as-cast and annealed BMG samples is interpreted in terms of free volume theory

The structural relaxation effect on the nanomechanical properties of a Ti-based bulk metallic glass

Energy Technology Data Exchange (ETDEWEB)

Huang, Yongjiang, E-mail: yjhuang@hit.edu.cn [State Key Laboratory of Advanced Welding Production Technology, Harbin Institute of Technology, Harbin 150001 (China); School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Harbin Institute of Technology, Ministry of Education, Harbin 150001 (China); Zhou, Binjun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Chiu, YuLung, E-mail: y.chiu@bham.ac.uk [School of Metallurgy and Materials, University of Birmingham, Edgbaston, Birmingham B15 2TT (United Kingdom); Fan, Hongbo [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Wang, Dongjun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China); Key Laboratory of Micro-Systems and Micro-Structures Manufacturing, Harbin Institute of Technology, Ministry of Education, Harbin 150001 (China); Sun, Jianfei; Shen, Jun [School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001 (China)

2014-09-01

Highlights: • The effect of structural relaxation on the nano-mechanical behaviors of BMGs is studied. • The indent load at first pop-in event, the hardness and Young’s modulus are enhanced after annealing. • The differences in nanomechanical properties can be attributed to their different atomic structure. - Abstract: Indentation experiments were performed on the as-cast and the annealed Ti-based bulk metallic glass samples to investigate the effect of structural relaxation on the nanomechanical behaviors of the material. The onset of pop-in event, Young’s modulus, and hardness were found to be sensitive to the structural relaxation of the testing material. The difference in nanomechanical properties between the as-cast and annealed BMG samples is interpreted in terms of free volume theory.

Hot-electron effect in spin relaxation of electrically injected electrons in intrinsic Germanium.

Science.gov (United States)

Yu, T; Wu, M W

2015-07-01

The hot-electron effect in the spin relaxation of electrically injected electrons in intrinsic germanium is investigated by the kinetic spin Bloch equations both analytically and numerically. It is shown that in the weak-electric-field regime with E ≲ 0.5 kV cm(-1), our calculations have reasonable agreement with the recent transport experiment in the hot-electron spin-injection configuration (2013 Phys. Rev. Lett. 111 257204). We reveal that the spin relaxation is significantly enhanced at low temperature in the presence of weak electric field E ≲ 50 V cm(-1), which originates from the obvious center-of-mass drift effect due to the weak electron-phonon interaction, whereas the hot-electron effect is demonstrated to be less important. This can explain the discrepancy between the experimental observation and the previous theoretical calculation (2012 Phys. Rev. B 86 085202), which deviates from the experimental results by about two orders of magnitude at low temperature. It is further shown that in the strong-electric-field regime with 0.5 ≲ E ≲ 2 kV cm(-1), the spin relaxation is enhanced due to the hot-electron effect, whereas the drift effect is demonstrated to be marginal. Finally, we find that when 1.4 ≲ E ≲ 2 kV cm(-1) which lies in the strong-electric-field regime, a small fraction of electrons (≲5%) can be driven from the L to Γ valley, and the spin relaxation rates are the same for the Γ and L valleys in the intrinsic sample without impurity. With the negligible influence of the spin dynamics in the Γ valley to the whole system, the spin dynamics in the L valley can be measured from the Γ valley by the standard direct optical transition method.

Stress relaxation of thermally bowed fuel pins

International Nuclear Information System (INIS)

Crossland, I.G.; Speight, M.V.

1983-01-01

The presence of cross-pin temperature gradients in nuclear reactor fuel pins produces differential thermal expansion which, in turn, causes the fuel pin to bow elastically. If the pin is restrained in any way, such thermal bowing causes the pin to be stressed. At high temperatures these stresses can relax by creep and it is shown here that this causes the pin to suffer an additional permanent deflection, so that when the cross-pin temperature difference is removed the pin remains bowed. By representing the cylindrical pin by an equivalent I-beam, the present work examines this effect when it takes place by secondary creep. Two restraint systems are considered, and it is demonstrated that the rate of relaxation depends mainly upon the creep equation, and hence the temperature, and also the magnitude of the initial stresses. (author)

Variational formulation of relaxed and multi-region relaxed magnetohydrodynamics

Science.gov (United States)

Dewar, R. L.; Yoshida, Z.; Bhattacharjee, A.; Hudson, S. R.

2015-12-01

> Ideal magnetohydrodynamics (IMHD) is strongly constrained by an infinite number of microscopic constraints expressing mass, entropy and magnetic flux conservation in each infinitesimal fluid element, the latter preventing magnetic reconnection. By contrast, in the Taylor relaxation model for formation of macroscopically self-organized plasma equilibrium states, all these constraints are relaxed save for the global magnetic fluxes and helicity. A Lagrangian variational principle is presented that leads to a new, fully dynamical, relaxed magnetohydrodynamics (RxMHD), such that all static solutions are Taylor states but also allows state with flow. By postulating that some long-lived macroscopic current sheets can act as barriers to relaxation, separating the plasma into multiple relaxation regions, a further generalization, multi-region relaxed magnetohydrodynamics (MRxMHD) is developed.

Relaxation and Distraction in Experimental Desensitization.

Science.gov (United States)

Weir, R. O.; Marshall, W. L.

1980-01-01

Compared experimental desensitization with a procedure that replaced relaxation with a distraction task and with an approach that combined both relaxation and distraction. Desensitization generally was more effective than the other two procedures. (Author)

DO FOOT REFLEXOLOGY AND RELAXATION TRAINING DECREASE PREMENSTRUAL SYMPTOMS IN ADOLESCENT FEMALES

Directory of Open Access Journals (Sweden)

Marwa A. Mohamed

2016-10-01

Full Text Available Background: Premenstrual syndrome is a current condition characterized by troublesome symptoms as tension, irritability, depression, headache, anxiety and loss of self-control, so the aim of this study was to investigate the effect of foot reflexology augmented with relaxation training on premenstrual syndrome in adolescent females. Methods: A sample of 50 volunteers, virgin females diagnosed as premenstrual syndrome was selected from the students of Faculty of Physical Therapy, Cairo University. Their age was ranged between 19 to 23 years with mean value of (21.53±2.27 yrs and BMI was ≤28 Kg/m² with mean value of (24.04±2.41 Kg/m².A detailed medical history was obtained to screen other pathological conditions that may affect the results. Females were randomly assigned into two equal groups. Group (A consisted of 25 subjects who received foot reflexology in addition to relaxation training techniques twice a week for 8 weeks. Group (B consisted of 25 patients, who received relaxation training techniques only twice a week for 8 weeks. Assessment of all subjects in both groups was carried out before and after the treatment program through heart rate, respiratory rate in addition to plasma cortisol level and daily symptoms report chart. Results: Showed a statistical highly significant decrease (p<0.001 in heart rate, respiratory rate, plasma cortisol level as well as daily symptoms report score in group (A while there was a statistical significant decrease (p<0.05 in all variables in group (B. Conclusions: Adding foot reflexology to relaxation training had a great positive effect on premenstrual syndrome in adolescent females than relaxation training only.

F-center mechanism of long-term relaxation in lead zirconate-titanate-based piezoelectric ceramics. 1. After-heating relaxation

Directory of Open Access Journals (Sweden)

V. M. Ishchuk

2015-12-01

The oxygen vacancies-based model for description of the long-time relaxation processes is suggested. The model takes into account oxygen vacancies on the sample’s surface ends, their conversion into F+- and F0-centers under external effects (due to the liberation of the pyroelectric charge and subsequent relaxation of these centers into the simple oxygen vacancies after the actions termination. The initial sample’s state is electroneutrality one. F-center formation leads to the violation of the original sample’s electroneutrality, and generates DC electric field into the sample. Relaxation of F-centers is accompanied by decreasing of electric field, induced by them, and dielectric constant relaxation as consequent effect.

Effects of relaxation of gluten network on rehydration kinetics of pasta.

Science.gov (United States)

Ogawa, Takenobu; Hasegawa, Ayako; Adachi, Shuji

2014-01-01

The aim of this study was to investigate the effects of the relaxation of the gluten network on pasta rehydration kinetics. The moisture content of pasta, under conditions where the effects of the diffusion of water on the moisture content were negligible, was estimated by extrapolating the average moisture content of pasta of various diameters to 0 mm. The moisture content of imaginary, infinitely thin pasta did not reach equilibrium even after 1 h of rehydration. The rehydration of pasta made of only gluten was also measured. The rate constants estimated by the Long and Richman equation for both the pasta indicated that the rehydration kinetics of infinitely thin pasta were similar to those of gluten pasta. These results suggest that the swelling of starch by fast gelatinization was restricted by the honeycomb structural network of gluten and the relaxation of the gluten network controlled pasta rehydration kinetics.

Temperature effects on loss of prestress due to relaxation of steel

International Nuclear Information System (INIS)

Appa Rao, G.; Yamini Sreevalli, I.; Meher Prasad, A.; Reddy, G.R.; Prabhakar, G.

2007-01-01

Prestressed concrete is used in general civil engineering applications and in nuclear power plants for a number of structures such as containments, reactor pressure vessels, missile shield members, reactor cavity walls etc. Loss of prestress in containment structures is a serious concern for the longevity rather than serviceability. Loss of prestress higher than the initially designed values has been reported by various agencies at a number of nuclear power plants with prestressed concrete containment structures. At present the codes specify the prestress losses in Nuclear Power Plant Containment (NPPC) structures for 50 years. However there is a continuous effort to improve the life of NPPC particularly for a design life of 100 years. The long-term losses are mainly due to relaxation of prestressing cables, creep and shrinkage of concrete. The loss of prestress due to relaxation of prestressing cables is considered to be severe due to temperature effects. In this paper an effort has been made to understand the loss of prestress due to relaxation of steel at different temperatures namely 20 degC, 25 degC, 30 degC, 35 degC, 40 degC and 45 degC and the results up to 1000 hrs to estimate the losses over longer life of structures. The initial prestress was maintained at 0.70 times guaranteed ultimate tensile strength (GUTS) of cables. The prestressing loss due to relaxation of prestressing cables increases as the temperature increases. (author)

Is cognitive behavioral therapy more effective than relaxation therapy in the treatment of anxiety disorders? A meta-analysis.

NARCIS (Netherlands)

Montero Marin, J.; Garcia-Campayo, J.; López-Montoyo, A.; Zabaleta-del-Olmo, E.; Cuijpers, P.

2017-01-01

Background It is not clear whether relaxation therapies are more or less effective than cognitive and behavioural therapies in the treatment of anxiety. The aims of the present study were to examine the effects of relaxation techniques compared to cognitive and behavioural therapies in reducing

The effect of relaxing music on heart rate and heart rate variability during ECG GATED-myocardial perfusion scintigraphy.

Science.gov (United States)

Tan, Yusuf Ziya; Ozdemir, Semra; Temiz, Ahmet; Celik, Fatmanur

2015-05-01

The positive changes in human behavior caused by relaxing music demonstrate the psychological effect of music on human body. A meta-analytical study has shown that relaxing music affects blood pressure and heart rate in coronary heart patients and cancer patients. The aim of our study is to research whether there is a significant effect on heart rate and heart rate variability due to listening to relaxing music during ECG GATED MPS imaging under gamma camera. The music group (n = 50 patients) could choose from 15 different musical types including folk music (no lyric). The other 50 patients were placed in a "no music group" and did not get headphones or any music. There was a statistically significant reduction in the heart rate of patients in the music group compared to those in the control group. Relaxing music provides great benefits to both patient and clinician. There is close relationship between relaxing music and health procedure, can use every area of the health noninvasiv, safe, cheap and is a method don't have side effect. Copyright © 2015 Elsevier Ltd. All rights reserved.

Contact induced spin relaxation in graphene spin valves with Al2O3 and MgO tunnel barriers

Directory of Open Access Journals (Sweden)

Walid Amamou

2016-03-01

Full Text Available We investigate spin relaxation in graphene by systematically comparing the roles of spin absorption, other contact-induced effects (e.g., fringe fields, and bulk spin relaxation for graphene spin valves with MgO barriers, Al2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by fitting the Hanle spin precession data with two models that include or exclude the effect of spin absorption. Results indicate that additional contact-induced spin relaxation other than spin absorption dominates the contact effect. For tunneling contacts, we find reasonable agreement between the two models with median discrepancy of ∼20% for MgO and ∼10% for Al2O3.

Effects of BM-573 on Endothelial Dependent Relaxation and Increased Blood Pressure at Early Stages of Atherosclerosis.

Directory of Open Access Journals (Sweden)

Miguel Romero

Full Text Available Endothelial dysfunction is considered to be an early event in atherosclerosis and plays a pivotal role in the development, progression and clinical complications of atherosclerosis. Previous studies have shown the beneficial effects of combined inhibition of thromboxane synthase and antagonism of thromboxane receptors by BM-573 on atherosclerosis; however our knowledge about the beneficial effects of BM-573 on endothelial function and increased blood pressure related to early stage of atherosclerosis is limited. In the present study, we investigated the effects of short-term (3 μM, 1 hour and chronic (10 mg/L, 8 weeks treatments with BM-573 on vasodilatory function, nitric oxide (NO bioavailability, oxidative stress and systolic blood pressure in 15 weeks old apolipoprotein E-deficient (ApoE-KO mice. ApoE-KO mice showed a reduced endothelium-derived relaxation. In addition, NO bioavailability was reduced and oxidative stress and blood pressure were increased in ApoE-KO mice versus wild-type mice. BM-573 treatments were able to improve the relaxation profile in ApoE-KO mice. Short-term effects of BM-573 were mainly mediated by an increased phosphorylation of both eNOS and Akt, whereas BM-573 in vivo treatment also reduced oxidative stress and restored NO bioavailability. In addition, chronic administration of BM-573 reduced systolic blood pressure in ApoE-KO mice. In conclusion, pharmacological modulation of TxA2 biosynthesis and biological activities by dual TP antagonism/TxAS inhibition with BM-573, already known to prevent plaque formation, has the potential to correct vasodilatory dysfunction at the early stages of atherosclerosis.

Stimulating and relaxing effect of apperception music in the context of martial arts

OpenAIRE

ŠPIČKA, Roman

2013-01-01

The work deals with the influence of music on mental and physical manifestations of a personality in the practice of the Taekwon-Do. The theoretical part describes the history and the present of the Taekwon-Do, the basic structure of the music therapy and various effects of music, Taekwon-Do exercises and a relaxation. The practical part compares four groups of probands who practiced or relaxed listening to a music or without any music. My research was focused on the emotional level and the h...

Relaxation processes during amorphous metal alloys heating

International Nuclear Information System (INIS)

Malinochka, E.Ya.; Durachenko, A.M.; Borisov, V.T.

1982-01-01

Behaviour of Te+15 at.%Ge and Fe+13 at.%P+7 at.%C amorphous metal alloys during heating has been studied using the method of differential scanning calorimetry (DSC) as the most convenient one for determination of the value of heat effects, activation energies, temperature ranges of relaxation processes. Thermal effects corresponding to high-temperature relaxation processes taking place during amorphous metal alloys (AMA) heating are detected. The change of ratio of relaxation peaks values on DSC curves as a result of AMA heat treatment can be explained by the presence of a number of levels of inner energy in amorphous system, separated with potential barriers, the heights of which correspond to certain activation energies of relaxation processes

Tuning the probe location on zwitterionic micellar system with variation of pH and addition of surfactants with different alkyl chains: solvent and rotational relaxation studies.

Science.gov (United States)

Banerjee, Chiranjib; Mandal, Sarthak; Ghosh, Surajit; Rao, Vishal Govind; Sarkar, Nilmoni

2012-09-13

In this manuscript, we have modulated the location of an anionic probe, Coumarin-343 (C-343) in a zwitterionic (N-hexadecyl-N,N-dimethylammonio-1-propanesulfonate (SB-16)) micellar system by three different approaches. The effect of addition of the surfactant sodium dodecyl sulfate (SDS) and the room temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium octylsulfate (EmimOs) and N,N-dimethylethanol hexanoate (DAH), to the micellar solution has been studied. The effect of pH variation has been studied as well using solvent and rotational measurements. Migration of the anionic probe, C-343, from the palisade layer of SB-16 micelle to the bulk water has been observed to varying extents with the addition of SDS and EmimOs. The effect is much more pronounced in the presence of SDS and can be ascribed to the presence of the long alkyl (dodecyl) chain on SDS which can easily orient itself and fuse inside the SB-16 micelle and facilitate the observed migration of the probe molecule. This phenomenon is confirmed by faster solvation and rotational relaxation of the investigated probe molecule. The analogous fusion process is difficult in case of EmimOs and DAH because of their comparatively smaller alkyl (octyl and hexanoate) chain. However, the direction of C-343 migration is reversed with the decrease of pH of the SB-16 micellar medium. An increase in the average solvation and rotational relaxation time of the probe in acidic medium has been observed. Since experimental conditions are maintained such that the probe molecules and the zwitterionic SB-16 micelles remain oppositely charged, the observed results can be attributed to the increased electrostatic interaction (attractive) between them. Temperature dependent study also supports this finding.

Transport relaxation measurements and glassy state effects in superconducting MgB2

International Nuclear Information System (INIS)

Olutas, M.; Yetis, H.; Altinkok, A.; Kilic, A.; Kilic, K.

2008-01-01

Time dependent effects in superconducting MgB 2 have been studied systematically for the first time by transport relaxation measurements (V-t curves) as a function of transport current (I), temperature (T) and external magnetic field (H). At very low dissipation levels (below ∼1 μV), it was observed that the sample voltage grows up smoothly in time by exhibiting the details of initial stage of relaxation process. At high dissipation levels, steady state corresponding to constant flow rate is maintained within a very short time and monitoring of details of flux dynamic evolving along sample becomes difficult on long time scales. Another interesting behavior is the appearance of voltage peak when the transport current was reduced to a finite value. After peak, it was observed that the sample voltage relaxes smoothly by leveling off within a very short time. The evolution of V-t curves suggests that formation of resistive flow channels along sample develops easily, which is quite similar to that of obtained for the superconducting ceramic samples whose grain boundaries are improved. Time dependent effects were also observed in magnetovoltage measurements (V-H curves) as the field sweep rate (dH/dt) varies. The observations were interpreted mainly in terms of flux trapping in grains

Peroxynitrite-induced relaxation in isolated canine cerebral arteries and mechanisms of action

International Nuclear Information System (INIS)

Li Jianfeng; Li Wenyan; Altura, Bella T.; Altura, Burton M.

2004-01-01

The present study was undertaken to determine the vascular actions of peroxynitrite (ONOO - ), the product of superoxide and nitric oxide (NO), in isolated canine cerebral arteries and to gain insight into its potential mechanisms of action. In the absence of any vasoactive agent, ONOO - (from 10 -7 to 10 -6 M) was able to reduce the basal tension. In prostaglandin F2α-precontracted canine basilar arterial rings, ONOO - elicited concentration-dependent relaxation at concentrations from 10 -8 to 10 -5 M. The effective concentrations producing approximately 50% maximal relaxation (EC 50 ) to ONOO - were 4.06 x 10 -6 and 4.12 x 10 -6 M in intact and denuded rings, respectively (P > 0.05). No significant differences in relaxation responses were found in ring preparations with or without endothelium (P > 0.05). The presence of either 5 μM methylene blue (MB) or 5 μM 1H-[1,2,4]oxadiazolo-[4,3-α]quinoxalin-1-one (ODQ) significantly inhibited the relaxations induced by ONOO - . Tetraethylammonium chloride (T-2265) significantly decreased the ONOO - -induced relaxations in a concentration-dependent manner. However, ONOO - had no effect on rings precontracted by high KCL (P > 0.05). Addition of low concentrations of calyculin A (50 nM) was able to abolish the ONOO - -induced relaxation. Furthermore, ONOO - significantly inhibited calcium-induced contractions of K + -depolarized canine cerebral rings in a concentration-related manner. Lastly, a variety of pharmacological agents and antagonists including L-NMMA, L-arginine, indomethacin, atropine, naloxone, diphenhydramine, cimetine, glibenclamide, haloperidol, etc., did not influence the relaxant effects of ONOO - on the rings. Our new results suggest that ONOO - -triggered relaxation, on canine cerebral arteries, is mediated by elevation of cyclic guanosine monophosphate (cGMP) levels, membrane hyperpolarization via K+ channel activation, activation of myosin light chain phosphatase activity, and interference with

Effects of different "relaxing" music styles on the autonomic nervous system.

Science.gov (United States)

Perez-Lloret, Santiago; Diez, Joaquín; Domé, María Natalia; Delvenne, Andrea Alvarez; Braidot, Nestor; Cardinali, Daniel P; Vigo, Daniel Eduardo

2014-01-01

The objective of this study was to assess the effects on heart rate variability (HRV) of exposure to different styles of "relaxing" music. Autonomic responses to musical stimuli were correlated with subjective preferences regarding the relaxing properties of each music style. Linear and nonlinear HRV analysis was conducted in 25 healthy subjects exposed to silence or to classical, new age or romantic melodies in a random fashion. At the end of the study, subjects were asked to choose the melody that they would use to relax. The low-to-high-frequency ratio was significantly higher when subjects were exposed to "new age" music when compared with silence (3.4 ± 0.3 vs. 2.6 ± 0.3, respectively, P classical" or "romantic" melodies (2.1 ± 0.4 and 2.2 ± 0.3). These results were related to a reduction in the high frequency component with "new age" compared to silence (17.4 ± 1.9 vs. 23.1 ± 1.1, respectively P music induced a shift in HRV from higher to lower frequencies, independently on the music preference of the listener.

Effect of relaxation and decay of a charge transfer shakeup satellite on Auger-electron spectroscopy spectra and Auger-photoelectron coincidence spectroscopy spectra of adsorbates

International Nuclear Information System (INIS)

Ohno, Masahide

2008-01-01

An electron excited to an unoccupied part of adsorbate-substrate hybrid states in a chemisorbed molecule by a resonant core electron excitation or charge transfer (CT) shakeup may delocalize on time scale of core-hole decay so that the excited core-hole state relaxes partly or completely to a fully relaxed one. The Auger decay of the fully relaxed core-hole state via the relaxation of the excited one introduces an additional feature in the resonant Auger-electron spectroscopy (RAES) spectrum and the AES spectrum. However, the additional feature in the RAES spectrum is a normal AES spectrum by decay of the fully relaxed core-hole state, whereas the one in the AES spectrum is the AES spectrum by decay of the fully relaxed core-hole state broadened by the photoelectron spectroscopy (PES) CT shakeup satellite weighted by the branching ratio of the relaxation width. The discrepancies between the AES spectrum measured at high above the ionization threshold and the additional feature in the RAES spectrum consist of the symmetric-like part by the decay of the fully relaxed core-hole state via the relaxation of the CT shakeup state and the asymmetric part by the direct decay of the shakeup states. The asymmetric part increases with a decrease in the hybridization strength. This explains the variation with the hybridization strength in the discrepancies between the RAES spectra and the AES spectra of chemisorbed molecules such as CO/Ni, CO/Cu and CO/Ag. A comparison of the singles PES spectrum with the one measured in coincidence with the AES main line of a selected kinetic energy (KE) provides the delocalization rate of the excited electron in the CT shakeup state as a function of photoelectron KE. The coincidence measurement to obtain the partial singles PES spectrum is discussed

Escape time, relaxation, and sticky states of a softened Henon-Heiles model: Low-frequency vibrational mode effects and glass relaxation

Science.gov (United States)

Toledo-Marín, J. Quetzalcóatl; Naumis, Gerardo G.

2018-04-01

Here we study the relaxation of a chain consisting of three masses joined by nonlinear springs and periodic conditions when the stiffness is weakened. This system, when expressed in their normal coordinates, yields a softened Henon-Heiles system. By reducing the stiffness of one low-frequency vibrational mode, a faster relaxation is enabled. This is due to a reduction of the energy barrier heights along the softened normal mode as well as for a widening of the opening channels of the energy landscape in configurational space. The relaxation is for the most part exponential, and can be explained by a simple flux equation. Yet, for some initial conditions the relaxation follows as a power law, and in many cases there is a regime change from exponential to power-law decay. We pinpoint the initial conditions for the power-law decay, finding two regions of sticky states. For such states, quasiperiodic orbits are found since almost for all components of the initial momentum orientation, the system is trapped inside two pockets of configurational space. The softened Henon-Heiles model presented here is intended as the simplest model in order to understand the interplay of rigidity, nonlinear interactions and relaxation for nonequilibrium systems such as glass-forming melts or soft matter. Our softened system can be applied to model β relaxation in glasses and suggest that local reorientational jumps can have an exponential and a nonexponential contribution for relaxation, the latter due to asymmetric molecules sticking in cages for certain orientations.

Relaxed states with plasma flow

International Nuclear Information System (INIS)

Avinash, K.; Taylor, J.B.

1991-01-01

In the theory of relaxation, a turbulent plasma reaches a state of minimum energy subject to constant magnetic helicity. In this state the plasma velocity is zero. Attempts have been made by introducing a number of different constraints, to obtain relaxed states with plasma flow. It is shown that these alternative constraints depend on two self-helicities, one for ions, and one for electrons. However, whereas there are strong arguments for the effective invariance of the original magnetic-helicity, these arguments do not apply to the self-helicities. Consequently the existence of relaxed states with flow remains in doubt. (author)

Effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese from goat milk.

Science.gov (United States)

Tirado, Diego F; Acevedo, Diofanor; Torres-Gallo, Ramiro

2018-01-01

Textural attributes are a manifestation of the rheological properties and physical structure of foods, cheeses among these. In order to describe these physical properties, the objective of this work was to analyse the effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese made from goat milk with 3.75% (F1), 4.00% (F2) and 4.25% (F3) fat content, through prediction made by a four-term Prony series based on Chen's model. For this, stress relaxation data and stress relaxation spectra were analysed. Moreover, textural attributes by texture profile analysis were measured. Physicochemical results were similar to those published by other authors, and all samples meet national and international standards. Results from this work showed that Chen's model could be successfully used to describe the effect of deformation history on the stress relaxation behaviour of Colombian Caribbean coastal cheese made from goat milk. F1 had the highest elastic response, with the most significant residual modules ( P 0 ) and relaxation times (τ 1 , τ 2 and τ 3 ). On the other hand, residual modules and relaxation times (τ 1 , τ 2 and τ 3 ) for cheeses F2 and F3 did not present statistically significant differences (p > 0.05). Besides, by interpretation of the stress relaxation spectra, F1 presented the firmest structure (greatest distribution function and relaxation time) which was characterised by the highest elastic behaviour. Finally, according to texture profile analysis test, F1 had the highest hardness, cohesiveness and chewiness, whereas F2 and F3 did not present statistically significant differences (p > 0.05) between them.

Is cognitive-behavioural therapy more effective than relaxation therapy in the treatment of anxiety disorders? A meta-analysis.

Science.gov (United States)

Montero-Marin, Jesus; Garcia-Campayo, Javier; López-Montoyo, Alba; Zabaleta-Del-Olmo, Edurne; Cuijpers, Pim

2018-07-01

It is not clear whether relaxation therapies are more or less effective than cognitive and behavioural therapies in the treatment of anxiety. The aims of the present study were to examine the effects of relaxation techniques compared to cognitive and behavioural therapies in reducing anxiety symptoms, and whether they have comparable efficacy across disorders. We conducted a meta-analysis of 50 studies (2801 patients) comparing relaxation training with cognitive and behavioural treatments of anxiety. The overall effect size (ES) across all anxiety outcomes, with only one combined ES in each study, was g = -0.27 [95% confidence interval (CI) = -0.41 to -0.13], favouring cognitive and behavioural therapies (number needed to treat = 6.61). However, no significant difference between relaxation and cognitive and behavioural therapies was found for generalized anxiety disorder, panic disorder, social anxiety disorder and specific phobias (considering social anxiety and specific phobias separately). Heterogeneity was moderate (I2 = 52; 95% CI = 33-65). The ES was significantly associated with age (p cognitive and/or behavioural therapy (p = 0.015), quality of intervention (p = 0.007), relaxation treatment format (p cognitive and behavioural therapies in the treatment of post-traumatic stress disorder, and obsessive-compulsive disorder and it might also be less effective at 1-year follow-up for panic, but there is no evidence that it is less effective for other anxiety disorders.

Relaxed Poisson cure rate models.

Science.gov (United States)

Rodrigues, Josemar; Cordeiro, Gauss M; Cancho, Vicente G; Balakrishnan, N

2016-03-01

The purpose of this article is to make the standard promotion cure rate model (Yakovlev and Tsodikov, ) more flexible by assuming that the number of lesions or altered cells after a treatment follows a fractional Poisson distribution (Laskin, ). It is proved that the well-known Mittag-Leffler relaxation function (Berberan-Santos, ) is a simple way to obtain a new cure rate model that is a compromise between the promotion and geometric cure rate models allowing for superdispersion. So, the relaxed cure rate model developed here can be considered as a natural and less restrictive extension of the popular Poisson cure rate model at the cost of an additional parameter, but a competitor to negative-binomial cure rate models (Rodrigues et al., ). Some mathematical properties of a proper relaxed Poisson density are explored. A simulation study and an illustration of the proposed cure rate model from the Bayesian point of view are finally presented. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effects of zoxazolamine and related centrally acting muscle relaxants on nigrostriatal dopaminergic neurons.

Science.gov (United States)

Matthews, R T; McMillen, B A; Speciale, S G; Jarrah, H; Shore, P A; Sanghera, M K; Shepard, P D; German, D C

1984-05-01

The effects of zoxazolamine (ZOX) and related centrally acting muscle relaxants on striatal dopamine (DA) metabolism and turnover, and substantia nigra zona compacta DA neuronal impulse flow were studied in rats. ZOX, chlorzoxazone and mephenesin, but not meprobamate, chloral hydrate, diazepam, pentobarbital, ethanol or dantrolene, decreased striatal DA metabolism without affecting striatal DA concentrations. More specifically, ZOX, as a representative muscle relaxant, was shown to decrease striatal DA turnover without directly affecting DA synthesis, catabolism, reuptake, or release. ZOX decreased nigral DA neuronal firing rates and dramatically decreased firing rate variability (normally many of the cells fire with bursting firing patterns but after ZOX the cells often fired with a very regular pacemaker-like firing pattern). ZOX and related centrally acting muscle relaxants appear to decrease striatal DA turnover by decreasing both neuronal firing rate and firing rate variability. The possible relationships between DA neuronal activity and muscle tone are discussed.

The entire mean stress relaxation effects of 0Cr18Ni10Ti piping steel

International Nuclear Information System (INIS)

Yang Bing; Zhao Yongxiang

2005-01-01

Experimental study is performed on the mean stress relaxation effects of the Chinese new piping material, 0Cr18Ni10Ti steel. Six sets of specimens are respectively fatigued under a strain-controlled mode with the six straining ratios (R ε ) of -1, -0.52, -0.22, 0.029, 0.18, and 0.48 by an improved test method implied with an maximum likelihood statistical principle. The test results reveal that the material exhibits a Masing behaviour and, surprisingly, involves an entire mean stress relaxation. A challenge is then emerging to the traditional same treat of straining ratio and stressing ratio (R σ ) in fatigue analysis and assessment. There is still no effective method to describe this kind of relaxation. However the R ε effects can represent the relaxation effects appropriately by investigation on the material random cyclic stress-strain (σ-ε) relations and strain-life (ε-N) relations with different R ε . The intrinsic randomness of the responses is taken into account on a probabilistic sense. Significant differences are observed of the material cyclic responses under different R ε . For σ-ε relations, the R ε effects act as a decreasing trend to the stress amplitudes with the increasing survival probability and confidence. The strongest effect appears at R ε of 0.029, and a weaker one acts as R ε is far away from zero. For ε-N relations, R ε greater than zero exhibits a positive effect on the fatigue lives of about 1.3 to 1.6 times under a survival probability of 0.999 and a confidence of 95%, while a negative effect is exhibited in case of R ε less than zero. Present work indicates that systematic researches should be made to give a reasonable fatigue prediction in service on a basis of cyclic strain inspection of structures. (authors)

The Relaxant Effect of Seed's Essential Oil and Oleo‑gum‑resin of ...

African Journals Online (AJOL)

kenchu‑to on spontaneous activity in the mouse small intestine. J Smooth Muscle Res. 2006;42:189‑201. 17. Gholamnezhad Z, Byrami G, Boskabady MH, Iranshahi M. Possible mechanism (s) of the relaxant effect of asafoetida. (Ferula assa‑foetida) ...

The benefit of heart rate variability biofeedback and relaxation training in reducing trait anxiety†

Science.gov (United States)

Lee, Jieun; Kim, Jung K; Wachholtz, Amy

2016-01-01

Previous research studies have indicated that biofeedback treatment and relaxation techniques are effective in reducing psychological and physical symptoms (Hammond, 2005; Manzoni, G. M., Pagnini, F., Castelnuovo, G., & Molinari, E., 2008). However, dearth of studies has compared heart rate variability (HRV) biofeedback treatment and relaxation training to reduce trait anxiety. The objective of this study was to determine the effect of HRV biofeedback treatment and relaxation training in reducing trait anxiety compared to control group without any treatment using students in a science and engineering university of South Korea. For the present study, a total of 15 graduate students with moderate level of trait anxiety were recruited for 4 individual sessions every two weeks. They were randomly assigned into three groups: biofeedback treatment (n = 5), relaxation training (n = 5), and no treatment control group (n = 5). Our results revealed significant difference in change score of trait anxiety between the HRV biofeedback treatment and the no treatment control group. However, no significant difference was found between the relaxation training group and the no treatment control group. In addition, there was no significant difference between the HRV biofeedback treatment and the relaxation training. Results of the present study indicate that there is potential benefit in utilizing HRV biofeedback treatment for stress management programs and/or anxiety reduction treatment PMID:27099546

Analysis of the role of nitric oxide in the relaxant effect of the crude extract and fractions from Eugenia uniflora in the rat thoracic aorta.

Science.gov (United States)

Wazlawik, E; Da Silva, M A; Peters, R R; Correia, J F; Farias, M R; Calixto, J B; Ribeiro-Do-Valle, R M

1997-04-01

This study has evaluated the possible role played by the L-arginine-nitric oxide pathway in the vasorelaxant action of the hydroalcoholic extract from Eugenia uniflora, and fractions from the extract, in rings of rat thoracic aorta. The addition of an increasing cumulative concentration of hydroalcoholic extract from E. uniflora (1-300 micrograms mL-1) caused a concentration-dependent relaxation response in intact endothelium-thoracic aorta rings pre-contracted with noradrenaline (30-100 nM). The IC50 value, with its respective confidence limit, and the maximum relaxation (Rmax) were 7.02 (4.77-10.00) micrograms mL-1 and 83.94 +/- 3.04%, respectively. The removal of the endothelium completely abolished these responses. The nitric oxide synthase inhibitors N omega-nitro-L-arginine (L-NOARG, 30 microM) and N omega-nitro-L-arginine methyl ester (L-NAME, 30 microM), inhibited the relaxation (Rmax) to -10.43 +/- 7.81% and -3.69 +/- 2.62%, respectively. In addition, L-arginine (1 mM), but not D-arginine (1 mM), completely reversed inhibition by L-NOARG. Methylene blue (30 microM), a soluble guanylate cyclase inhibitor, reduced the relaxation induced by the extract to 14.60 +/- 7.40%. These data indicate that in the rat thoracic aorta the hydroalcoholic extract, and its fractions, from the leaves of E. uniflora have graded and endothelium-dependent vasorelaxant effects.

Effect of iodine impurity on relaxation of photoexcited silver chloride

International Nuclear Information System (INIS)

Vostrikova, Yu. V.; Klyuev, V. G.

2008-01-01

The time and temperature dependences of relaxation of excited AgCl and AgCl:I crystals is studied by the method of photostimulated flash of luminescence. The presence of iodine impurity in silver chloride gives rise to hole recombination (luminescence) centers and hole traps in the band gap. It is shown that the main contribution to the decrease in the concentration of electrons localized at deep traps is made by the recombination of electrons with holes released thermally from shallow localization levels (iodine-related centers). Estimation of activation energy for the relaxation process showed that these energies for the AgCl and AgCl:I samples under study are the same within the experimental error and are equal to E rel1 = 0.01 ± 0.0005 eV for the initial stage of relaxation and E rel2 = 0.09 ± 0.005 eV for the final state. This fact indicates that the majority of hole traps involved in the relaxation process in AgCl are related to iodine impurity. In the course of thermal relaxation in AgCl, relocalization of nonequilibrium charge carriers from shallow levels to deep levels is observed. The depth of the corresponding trap is E arl = 0.174 ± 0.03 eV.

Skeletal muscle relaxant effect of a standardized extract of Valeriana officinalis L. after acute administration in mice

Directory of Open Access Journals (Sweden)

Dorian Caudal

2018-04-01

Full Text Available Valeriana officinalis L. root extracts are traditionally taken for their sedative and anxiolytic properties and are also used for muscle relaxation. Relaxant effects were clearly observed on smooth muscle whereas data on effects on skeletal muscle are scarce and inconsistent. The aim of this study was to assess whether a standardized extract (SE of V. officinalis had myorelaxant effects by decreasing skeletal muscle strength and/or neuromuscular tone in mice. Mice received an acute dose of V. officinalis SE (2 or 5 g/kg per os or tetrazepam (10 mg/kg ip, a standard myorelaxant drug. Thirty minutes later, the maximal muscle strength was measured using a grip test, while global skeletal muscle function (endurance and neuromuscular tone was assessed in a wire hanging test. Compared to tetrazepam, both doses of V. officinalis SE induced a pronounced decrease in skeletal muscle strength without any significant effects on endurance and neuromuscular tone. This study provides clear evidence that the extract of V. officinalis tested has a relaxant effect on skeletal muscle. By decreasing skeletal muscle strength without impacting endurance and neuromuscular tone, V. officinalis SE could induce less undesirable side effects than standard myorelaxant agents, and be particularly useful for avoiding falls in the elderly. Keywords: Valeriana officinalis, Skeletal muscle relaxant, Strength, Hydroethanolic root extract, Acute treatment, Mouse

Anisotropic temperature relaxation of plasmas in an external magnetic field

International Nuclear Information System (INIS)

Hassan, M.H.A.

1977-01-01

The magnetized kinetic equation derived in an earlier paper (Hassan and Watson, 1977) is used to study the problem of relaxation of anisotropic electron and ion temperatures in a magnetized plasma. In the case of anisotropic electron temperature relaxation, it is shown that for small anisotropies the exchange of energy within the electrons between the components parallel and perpendicular to the magnetic field direction determine the relaxation rate. For anisotropic ion temperature relaxation it is shown that the essential mechanism for relaxation is provided by energy transfer between ions and electrons, and that the expression for the relaxation rate perpendicular to the magnetic field contains a significant term proportional to ln eta 0 ln (msub(e)/msub(i)) (where eta 0 = Ωsub(e)/ksub(D)Vsub(e perpendicular to)), in addition to the term proportional to the Coulomb logarithm. (author)

The Effect of Relaxation Training on Symptoms of Anxiety and Depression in Patients with Breast Cancer

Directory of Open Access Journals (Sweden)

Meral Demiralp

2011-04-01

Full Text Available AIM: The purpose of this study was to investigate the effect of progressive muscle relaxation training on anxiety and depression in Turkish women with breast cancer undergoing adjuvant chemotherapy. METHOD: Data were collected between March 2005–2006. The sample of the study consisted of 27 newly diagnosed breast cancer patients who had planned to be cured with adjuvant chemotherapy. Patients who met these study criteria were accepted to the research programme and assigned to one of two groups, either progressive muscle relaxation (PMR group (n = 14 or control (n = 13 group sequentially. The effect of the progressive muscle relaxation training was measured at different stages of the treatment. A data collection form and Hospital Anxiety and Depression Scale were used to collect the data. In our research, for statistical analysis of data, parametric and nonparametric tests were used according to data range. Values of p0.05. CONCLUSION: Consequently, it was determined that relaxation exercises have no any significant effect on the symptoms of anxiety and depression alone. Based upon these results it was suggested that anxiety and depression symptoms must be assessed again by using different intervention modalities with different research designs and instruments. [TAF Prev Med Bull 2011; 10(2.000: 165-174

Effects of surface relaxation and reconstruction on the vibration characteristics of nanobeams

International Nuclear Information System (INIS)

Zhang, Wen-Ming; Hu, Kai-Ming; Peng, Zhi-Ke; Meng, Guang; Yang, Bin

2016-01-01

Surface effects on the free vibration characteristics of nanobeams are investigated by a modified continuum model. In this paper, the relationship between the parameters of the modified continuum model of surface effects including surface elasticity, surface density, and residual surface stresses, and the parameters of the atomistic lattice model such as surface relaxation and reconstruction in nanobeams is characterized by an atomistic lattice model. The surface effects are incorporated into nanobeams to develop a modified continuum model depicting the free vibrational behavior of nanobeams. The model is validated with the experimental data of an effective size-dependent Young’s modulus and the previous theoretical results. The results demonstrate that both surface elasticity and surface density vary exponentially with surface layer thickness. Therefore, surface elasticity and density can be affected by surface relaxation and residual surface stresses can be induced by surface reconstruction. The natural frequencies of doubly clamped nanobeams can be affected by the dimensions of the nanobeams, surface layer thickness, and residual surface stress. This work may be helpful for understanding surface effects and their influence on the vibrational behavior of nanobeams. (paper)

Effect of Traffic Noise and Relaxations Sounds on Pedestrian Walking Speed

Directory of Open Access Journals (Sweden)

Marek Franěk

2018-04-01

Full Text Available Exposure to noise in everyday urban life is considered to be an environmental stressor. A specific outcome of reactions to environmental stress is a fast pace of life that also includes a faster pedestrian walking speed. The present study examined the effect of listening to annoying acoustical stimuli (traffic noise compared with relaxation sounds (forest birdsong on walking speed in a real outdoor urban environment. The participants (N = 83 walked along an urban route of 1.8 km. They listened to either traffic noise or forest birdsong, or they walked without listening to any acoustical stimuli in the control condition. The results showed that participants listening to traffic noise walked significantly faster on the route than both the participants listening to forest birdsong sounds and the participants in the control condition. Participants who listened to forest birdsong walked slightly slower than those under control conditions; however, this difference was not significant. Analysis of the walk experience showed that participants who listened to forest birdsong during the walk liked the route more than those who listened to traffic sounds. The study demonstrated that exposure to traffic noise led to an immediate increase in walking speed. It was also shown that exposure to noise may influence participants’ perception of an environment. The same environment may be more liked in the absence of noise or in the presence of relaxation sounds. The study also documented the positive effect of listening to various kinds of relaxation sounds while walking in an outdoor environment with traffic noise.

Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Elkins, Madeline H.; Williams, Holly L. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Neumark, Daniel M., E-mail: dneumark@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2016-05-14

The excited state relaxation dynamics of the solvated electron in H{sub 2}O and D{sub 2}O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H{sub 2}O and 102 ± 8 fs in D{sub 2}O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

Isotope effect on hydrated electron relaxation dynamics studied with time-resolved liquid jet photoelectron spectroscopy

Science.gov (United States)

Elkins, Madeline H.; Williams, Holly L.; Neumark, Daniel M.

2016-05-01

The excited state relaxation dynamics of the solvated electron in H2O and D2O are investigated using time-resolved photoelectron spectroscopy in a liquid microjet. The data show that the initial excited state decays on a time scale of 75 ± 12 fs in H2O and 102 ± 8 fs in D2O, followed by slower relaxation on time scales of 400 ± 70 fs and 390 ± 70 fs that are isotopically invariant within the precision of our measurements. Based on the time evolution of the transient signals, the faster and slower time constants are assigned to p → s internal conversion (IC) of the hydrated electron and relaxation on the ground electronic state, respectively. This assignment is consistent with the non-adiabatic mechanism for relaxation of the hydrated electron and yields an isotope effect of 1.4 ± 0.2 for IC of the hydrated electron.

Slow relaxation in weakly open rational polygons.

Science.gov (United States)

Kokshenev, Valery B; Vicentini, Eduardo

2003-07-01

The interplay between the regular (piecewise-linear) and irregular (vertex-angle) boundary effects in nonintegrable rational polygonal billiards (of m equal sides) is discussed. Decay dynamics in polygons (of perimeter P(m) and small opening Delta) is analyzed through the late-time survival probability S(m) approximately equal t(-delta). Two distinct slow relaxation channels are established. The primary universal channel exhibits relaxation of regular sliding orbits, with delta=1. The secondary channel is given by delta>1 and becomes open when m>P(m)/Delta. It originates from vertex order-disorder dual effects and is due to relaxation of chaoticlike excitations.

Improving the Performance of Poor Readers through Autogenic Relaxation Training.

Science.gov (United States)

Frey, Herbert

1980-01-01

Reports that the addition of 15 minutes of relaxation training to weekly remedial reading periods for disabled readers throughout a school year raised concentration levels and decreased anxiety, neuroticism, and number of reading errors. Describes a few types of relaxation exercises that may be helpful. (ET)

The effect of the Magnus force on skyrmion relaxation dynamics

OpenAIRE

Brown, Barton L.; Täuber, Uwe C.; Pleimling, Michel

2018-01-01

We perform systematic Langevin molecular dynamics simulations of interacting skyrmions in thin films. The interplay between Magnus force, repulsive skyrmion-skyrmion interaction and thermal noise yields different regimes during non-equilibrium relaxation. In the noise-dominated regime the Magnus force enhances the disordering effects of the thermal noise. In the Magnus-force-dominated regime, the Magnus force cooperates with the skyrmion-skyrmion interaction to yield a dynamic regime with slo...

Vibrational Energy Relaxation in Water-Acetonitrile Mixtures

NARCIS (Netherlands)

Cringus, Dan; Yeremenko, Sergey; Pshenichnikov, Maxim S.; Wiersma, Douwe A.; Kobayashi, Takayoshi; Kobayashi, Tetsuro; Nelson, Keith A.; Okada, Tadashi; Silvestri, Sandro De

2004-01-01

IR pump-probe spectroscopy is used to study the effect of hydrogen bonding on the vibrational energy relaxation pathways. Hydrogen bonding accelerates the population relaxation from 12ps in diluted acetonitrile solution to 700fs in bulk water.

Proton T2 relaxation effect of superparamagnetic iron oxide. Comparison between fast spin echo and conventional spin echo sequence

International Nuclear Information System (INIS)

Tanimoto, Akihiro; Satoh, Yoshinori; Higuchi, Nobuya; Izutsu, Mutsumu; Yuasa, Yuji; Hiramatsu, Kyoichi

1995-01-01

Superparamagnetic iron oxide (SPIO) particles have been known to show a great T 2 relaxation effect in the liver, which contributes to significant liver signal decrease and detection of hepatic neoplasms. Recently, fast spin echo (FSE) sequence with less scanning time than conventional spin echo (SE) sequence has been rapidly introduced in clinical MR imaging. To investigate whether SPIO would show decreased T 2 relaxation effect on FSE, we obtained T 2 relaxivity (R2) of SPIO in vitro and liver signal decrease caused by SPIO in vivo. SPIO showed 20% less R2 on Carr-Purcell-Meiboom-Gill (CPMG) sequence than on SE. Relative liver signal-to-noise ratio (SNR) decrease caused by SPIO was significantly smaller (p 2 relaxation effect on FSE than on SE. However, further studies will be required to assess the diagnostic capability of SPIO on FSE, in the detection of hepatic neoplasms. (author)

Transport relaxation measurements and glassy state effects in superconducting MgB{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Olutas, M. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)], E-mail: olutas_m@ibu.edu.tr; Yetis, H.; Altinkok, A.; Kilic, A.; Kilic, K. [Abant Izzet Baysal University, Department of Physics, Turgut Gulez Research Laboratory, 14280 Bolu (Turkey)

2008-09-15

Time dependent effects in superconducting MgB{sub 2} have been studied systematically for the first time by transport relaxation measurements (V-t curves) as a function of transport current (I), temperature (T) and external magnetic field (H). At very low dissipation levels (below {approx}1 {mu}V), it was observed that the sample voltage grows up smoothly in time by exhibiting the details of initial stage of relaxation process. At high dissipation levels, steady state corresponding to constant flow rate is maintained within a very short time and monitoring of details of flux dynamic evolving along sample becomes difficult on long time scales. Another interesting behavior is the appearance of voltage peak when the transport current was reduced to a finite value. After peak, it was observed that the sample voltage relaxes smoothly by leveling off within a very short time. The evolution of V-t curves suggests that formation of resistive flow channels along sample develops easily, which is quite similar to that of obtained for the superconducting ceramic samples whose grain boundaries are improved. Time dependent effects were also observed in magnetovoltage measurements (V-H curves) as the field sweep rate (dH/dt) varies. The observations were interpreted mainly in terms of flux trapping in grains.

Effect of a muscle relaxant, chlorphenesin carbamate, on the spinal neurons of rats.

Science.gov (United States)

Kurachi, M; Aihara, H

1984-09-01

The effects of chlorphenesin carbamate (CPC) and mephenesin on spinal neurons were investigated in spinal rats. CPC (50 mg/kg i.v.) inhibited the mono-(MSR) and poly-synaptic reflex (PSR), the latter being more susceptible than the former to CPC depression. Mephenesin also inhibited MSR and PSR, though the effects were short in duration. CPC had no effect on the dorsal root potential evoked by the stimulation of the dorsal root, while mephenesin reduced the dorsal root-dorsal root reflex. The excitability of motoneuron was reduced by the administration of CPC or mephenesin. The excitability of primary afferent terminal was unchanged by CPC, while it was inhibited by mephenesin. Neither CPC nor mephenesin influenced the field potential evoked by the dorsal root stimulation. Both CPC and mephenesin had no effect on the synaptic recovery. These results suggest that both CPC and mephenesin inhibit the firing of motoneurons by stabilizing the neuronal membrane, while mephenesin additionally suppresses the dorsal root reflex and the excitability of the primary afferent terminal. These inhibitory actions of CPC on spinal activities may contribute, at least partly, to its muscle relaxing action.

Magnetic Resonance Fingerprinting with short relaxation intervals.

Science.gov (United States)

Amthor, Thomas; Doneva, Mariya; Koken, Peter; Sommer, Karsten; Meineke, Jakob; Börnert, Peter

2017-09-01

The aim of this study was to investigate a technique for improving the performance of Magnetic Resonance Fingerprinting (MRF) in repetitive sampling schemes, in particular for 3D MRF acquisition, by shortening relaxation intervals between MRF pulse train repetitions. A calculation method for MRF dictionaries adapted to short relaxation intervals and non-relaxed initial spin states is presented, based on the concept of stationary fingerprints. The method is applicable to many different k-space sampling schemes in 2D and 3D. For accuracy analysis, T 1 and T 2 values of a phantom are determined by single-slice Cartesian MRF for different relaxation intervals and are compared with quantitative reference measurements. The relevance of slice profile effects is also investigated in this case. To further illustrate the capabilities of the method, an application to in-vivo spiral 3D MRF measurements is demonstrated. The proposed computation method enables accurate parameter estimation even for the shortest relaxation intervals, as investigated for different sampling patterns in 2D and 3D. In 2D Cartesian measurements, we achieved a scan acceleration of more than a factor of two, while maintaining acceptable accuracy: The largest T 1 values of a sample set deviated from their reference values by 0.3% (longest relaxation interval) and 2.4% (shortest relaxation interval). The largest T 2 values showed systematic deviations of up to 10% for all relaxation intervals, which is discussed. The influence of slice profile effects for multislice acquisition is shown to become increasingly relevant for short relaxation intervals. In 3D spiral measurements, a scan time reduction of 36% was achieved, maintaining the quality of in-vivo T1 and T2 maps. Reducing the relaxation interval between MRF sequence repetitions using stationary fingerprint dictionaries is a feasible method to improve the scan efficiency of MRF sequences. The method enables fast implementations of 3D spatially

Repeatability and reliability of muscle relaxation properties induced by motor cortical stimulation.

Science.gov (United States)

Molenaar, Joery P; Voermans, Nicol C; de Jong, Lysanne A; Stegeman, Dick F; Doorduin, Jonne; van Engelen, Baziel G

2018-03-15

Impaired muscle relaxation is a feature of many neuromuscular disorders. However, there are few tests available to quantify muscle relaxation. Transcranial magnetic stimulation (TMS) of the motor cortex can induce muscle relaxation by abruptly inhibiting corticospinal drive. The aim of our study is to investigate if repeatability and reliability of TMS-induced relaxation is greater than voluntary relaxation. Furthermore, effects of sex, cooling and fatigue on muscle relaxation properties were studied. Muscle relaxation of deep finger flexors was assessed in twenty-five healthy subjects (14 M and 11 F, aged 39.1{plus minus}12.7 and 45.3{plus minus}8.7 years old, respectively) using handgrip dynamometry. All outcome measures showed greater repeatability and reliability in TMS-induced relaxation compared to voluntary relaxation. The within-subject coefficient of variability of normalized peak relaxation rate was lower in TMS-induced relaxation than in voluntary relaxation (3.0 vs 19.7% in men, and 6.1 vs 14.3% in women). The repeatability coefficient was lower (1.3 vs 6.1 s -1 in men and 2.3 vs 3.1 s -1 in women), and the intraclass correlation coefficient was higher (0.95 vs 0.53 in men and 0.78 vs 0.69 in women), for TMS-induced relaxation compared to voluntary relaxation. TMS enabled to demonstrate slowing effects of sex, muscle cooling, and muscle fatigue on relaxation properties that voluntary relaxation could not. In conclusion, repeatability and reliability of TMS-induced muscle relaxation was greater compared to voluntary muscle relaxation. TMS-induced muscle relaxation has the potential to be used in clinical practice for diagnostic purposes and therapy effect monitoring in patients with impaired muscle relaxation.

Effect of biliary cirrhosis on nonadrenergic noncholinergic-mediated relaxation of rat corpus cavernosum: Role of nitric oxide pathway and endocannabinoid system

Directory of Open Access Journals (Sweden)

Dehpour A.R.

2008-06-01

Full Text Available Background: Relaxation of the corpus cavernosum plays a major role in penile erection. Nitric oxide (NO is known to be the most important factor mediating relaxation of corpus cavernosum, which is mainly derived from nonadrenergic noncholinergic (NANC nerves. The aim of the present study was to investigate the effect of biliary cirrhosis on nonadrenergic noncholinergic (NANC-mediated relaxation of rat corpus cavernosum as well as the possible relevant roles of endocannabinoid and nitric oxide systems.Methods: Corporal strips from sham-operated and biliary cirrhotic rats were mounted under tension in a standard oxygenated organ bath with guanethidine sulfate (5 µM and atropine (1 µM to induce adrenergic and cholinergic blockade. The strips were precontracted with phenylephrine hydrochloride (7.5 µM and electrical field stimulation was applied at different frequencies (2, 5, 10, 15 Hz to obtain NANC-mediated relaxation. In separate precontracted strips of the sham and cirrhotic groups, the concentration-dependent relaxant responses to sodium nitroprusside (10 nM-1mM, as an NO donor, were assessed.  Results: The NANC-mediated relaxation was significantly enhanced in cirrhotic animals (P<0.01. Anandamide potentiated the relaxations in both groups (P<0.05. The cannabinoid CB1 receptor antagonist AM251 (10 µM and the vanilloid receptor antagonist capsazepine (10 µM each significantly prevented the enhanced relaxations in cirrhotic rats (P<0.01. The CB2 receptor antagonist AM630 had no effect on relaxations in the cirrhotic group. In a concentration-dependent manner, L-NAME (30-1000 nM inhibited relaxations in both the sham and cirrhotic groups, although cirrhotic groups were more resistant to the inhibitory effects of L-NAME. The degree of relaxation induced by sodium nitroprusside (10 nM-1 mM was similar in the two groups.Conclusions: Biliary cirrhosis enhances the neurogenic relaxation in rat corpus cavernosum probably via the NO pathway and

Relaxation dynamics following transition of solvated electrons

International Nuclear Information System (INIS)

Barnett, R.B.; Landman, U.; Nitzan, A.

1989-01-01

Relaxation dynamics following an electronic transition of an excess solvated electron in clusters and in bulk water is studied using an adiabatic simulation method. In this method the solvent evolves classically and the electron is constrained to a specified state. The coupling between the solvent and the excess electron is evaluated via the quantum expectation value of the electron--water molecule interaction potential. The relaxation following excitation (or deexcitation) is characterized by two time scales: (i) a very fast (/similar to/20--30 fs) one associated with molecular rotations in the first solvation shell about the electron, and (ii) a slower stage (/similar to/200 fs), which is of the order of the longitudinal dielectric relaxation time. The fast relaxation stage exhibits an isotope effect. The spectroscopical consequences of the relaxation dynamics are discussed

Effects of Stress and Relaxation on Central Pain Modulation in Chronic Whiplash and Fibromyalgia Patients Compared to Healthy Controls.

Science.gov (United States)

Coppieters, Iris; Cagnie, Barbara; Nijs, Jo; van Oosterwijck, Jessica; Danneels, Lieven; De Pauw, Robby; Meeus, Mira

2016-03-01

Compelling evidence has demonstrated that impaired central pain modulation contributes to persistent pain in patients with chronic whiplash associated disorders (WAD) and fibromyalgia (FM). However, there is limited research concerning the influence of stress and relaxation on central pain modulation in patients with chronic WAD and FM. The present study aims to investigate the effects of acute cognitive stress and relaxation on central pain modulation in chronic WAD and FM patients compared to healthy individuals. A randomized crossover design was employed. The present study took place at the University of Brussels, the University Hospital Brussels, and the University of Antwerp. Fifty-nine participants (16 chronic WAD patients, 21 FM, 22 pain-free controls) were enrolled and subjected to various pain measurements. Temporal summation (TS) of pain and conditioned pain modulation (CPM) were evaluated. Subsequently, participants were randomly allocated to either a group that received progressive relaxation therapy or a group that performed a battery of cognitive tests (= cognitive stressor). Afterwards, all pain measurements were repeated. One week later participant groups were switched. A significant difference was found between the groups in the change in TS in response to relaxation (P = 0.008) and cognitive stress (P = 0.003). TS decreased in response to relaxation and cognitive stress in chronic WAD patients and controls. In contrast, TS increased after both interventions in FM patients. CPM efficacy decreased in all 3 groups in response to relaxation (P = 0.002) and cognitive stress (P = 0.001). The obtained results only apply for a single session of muscle relaxation therapy and cognitive stress, whereby no conclusions can be made for effects on pain perception and modulation of chronic cognitive stress and long-term relaxation therapies. A single relaxation session as well as cognitive stress may have negative acute effects on pain modulation in patients with

Real-time observation of cascaded electronic relaxation processes in p-Fluorotoluene

Science.gov (United States)

Hao, Qiaoli; Deng, Xulan; Long, Jinyou; Wang, Yanmei; Abulimiti, Bumaliya; Zhang, Bing

2017-08-01

Ultrafast electronic relaxation processes following two photoexcitation of 400 nm in p-Fluorotoluene (pFT) have been investigated utilizing time-resolved photoelectron imaging coupled with time-resolved mass spectroscopy. Cascaded electronic relaxation processes started from the electronically excited S2 state are directly imaged in real time and well characterized by two distinct time constants of 85 ± 10 fs and 2.4 ± 0.3 ps. The rapid component corresponds to the lifetime of the initially excited S2 state, including the structure relaxation from the Franck-Condon region to the conical intersection of S2/S1 and the subsequent internal conversion to the highly excited S1 state. While, the slower relaxation constant is attributed to the further internal conversion to the high levels of S0 from the secondarily populated S1 locating in the channel three region. Moreover, dynamical differences with benzene and toluene of analogous structures, including, specifically, the slightly slower relaxation rate of S2 and the evidently faster decay of S1, are also presented and tentatively interpreted as the substituent effects. In addition, photoelectron kinetic energy and angular distributions reveal the feature of accidental resonances with low-lying Rydberg states (the 3p, 4s and 4p states) during the multi-photon ionization process, providing totally unexpected but very interesting information for pFT.

Predicting the effect of relaxation during frequency-selective adiabatic pulses

Science.gov (United States)

Pfaff, Annalise R.; McKee, Cailyn E.; Woelk, Klaus

2017-11-01

Adiabatic half and full passages are invaluable for achieving uniform, B1-insensitive excitation or inversion of macroscopic magnetization across a well-defined range of NMR frequencies. To accomplish narrow frequency ranges with adiabatic pulses (computer-calculated data with experimental results demonstrates that, in non-viscous, small-molecule fluids, it is possible to model magnetization and relaxation by considering standard T1 and T2 relaxation in the traditional rotating frame. The proposed model is aimed at performance optimizations of applications in which these pulses are employed. It differs from previous reports which focused on short high-power adiabatic pulses and relaxation that is governed by dipole-dipole interactions, cross polarization, or chemical exchange.

Acute effects of 15min static or contract-relax stretching modalities on plantar flexors neuromuscular properties.

Science.gov (United States)

Babault, Nicolas; Kouassi, Blah Y L; Desbrosses, Kevin

2010-03-01

The present study aimed to investigate the immediate effects of 15 min static or sub-maximal contract-relax stretching modalities on the neuromuscular properties of plantar flexor muscles. Ten male volunteers were tested before and immediately after 15 min static or contract-relax stretching programs of plantar flexor muscles (20 stretches). Static stretching consisted in 30s stretches to the point of discomfort. For the contract-relax stretching modality, subjects performed 6s sub-maximal isometric plantar flexion before 24s static stretches. Measurements included maximal voluntary isometric torque (MVT) and the corresponding electromyographic activity of soleus (SOL) and medial gastrocnemius (MG) muscles (RMS values), as well as maximal peak torque (Pt) elicited at rest by single supramaximal electrical stimulation of the tibial nerve. After 15 min stretching, significant MVT and SOL RMS decreases were obtained (-6.9+/-11.6% and -6.5+/-15.4%, respectively). No difference was obtained between stretching modalities. Pt remained unchanged after stretching. MG RMS changes were significantly different between stretching modalities (-9.4+/-18.3% and +3.5+/-11.6% after static and contract-relax stretching modalities, respectively). These findings indicated that performing 15 min static or contract-relax stretching had detrimental effects on the torque production capacity of plantar flexor muscles and should be precluded before competition. Mechanisms explaining this alteration seemed to be stretch modality dependent. Copyright 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Multi-region relaxed Hall magnetohydrodynamics with flow

Energy Technology Data Exchange (ETDEWEB)

Lingam, Manasvi, E-mail: mlingam@princeton.edu [Department of Astrophysical Sciences, Princeton University, Princeton, New Jersey 08544 (United States); Abdelhamid, Hamdi M., E-mail: hamdi@ppl.k.u-tokyo.ac.jp [Graduate School of Frontier Sciences, The University of Tokyo, Kashiwanoha, Kashiwa, Chiba 277-8561 (Japan); Physics Department, Faculty of Science, Mansoura University, Mansoura 35516 (Egypt); Hudson, Stuart R., E-mail: shudson@pppl.gov [Princeton Plasma Physics Laboratory, PO Box 451, Princeton, New Jersey 08543 (United States)

2016-08-15

The recent formulations of multi-region relaxed magnetohydrodynamics (MRxMHD) have generalized the famous Woltjer-Taylor states by incorporating a collection of “ideal barriers” that prevent global relaxation and flow. In this paper, we generalize MRxMHD with flow to include Hall effects, and thereby obtain the partially relaxed counterparts of the famous double Beltrami states as a special subset. The physical and mathematical consequences arising from the introduction of the Hall term are also presented. We demonstrate that our results (in the ideal MHD limit) constitute an important subset of ideal MHD equilibria, and we compare our approach against other variational principles proposed for deriving the partially relaxed states.

A comparison of the effects of reflexology and relaxation on pain in women with multiple sclerosis.

Science.gov (United States)

Nazari, Fatemeh; Soheili, Mozhgan; Hosseini, SayedMohsen; Shaygannejad, Vahid

2016-03-01

Pain is a common and significant symptom in many individuals with multiple sclerosis (MS). The presence and severity of pain in individuals with MS has also been shown to be associated with higher levels of depression, functional impairment, and fatigue. It is common for MS patients and their caregivers to worry about narcotic addiction in the management of chronic pain. Therefore, this study aimed to determine and compare the effects of reflexology and relaxation on pain in women suffering from MS. This study was a single-blind randomized clinical trial performed on 75 patients with MS referred to the MS Clinic of Ayatollah Kashani Hospital (Isfahan, Iran). After simple non-random sampling, using the minimization method, participants were randomly assigned to the three groups of reflexology, relaxation, and control. In the experimental groups, foot reflexology and relaxation interventions (Jacobson and Benson) were performed within 4 weeks, twice a week for 40 min. The control group received routine care and medical treatment as directed by a doctor. Data were collected using the Numerical Rating Scale before, immediately after, and 2 months after interventions in all three groups. Data analysis was performed using SPSS version 18 and descriptive and inferential statistical tests. Findings obtained from analysis of variance (ANOVA) showed no significant differences between mean pain intensity scores in the three groups preintervention and 2 months after interventions (p > 0.05). However, this difference was statistically significant immediately after the study (p reflexology and relaxation (p  0.05). Furthermore, Fisher's least significant difference (LSD) revealed a significantly higher reduction in pain intensity scores in the reflexology group after the intervention, compared with the two other groups, but showed no significant differences between relaxation and control groups. There were no significant differences between the three groups 2 months

Effect of high pressure on the relaxation dynamics of glass-forming liquids

Energy Technology Data Exchange (ETDEWEB)

Paluch, M; Grzybowska, K; Grzybowski, A [Institute of Physics, Silesian University, ulica Uniwersytecka 4, 40-007 Katowice (Poland)

2007-05-23

A glass is usually formed by cooling a liquid at a rate sufficient to avoid crystallization. In the vicinity of the glass transition the structural relaxation time increases with lowering temperature in a non-Arrhenius fashion and the structural relaxation function reveals a non-Debye behaviour. However, liquid can be also vitrified by keeping it at a constant temperature and increasing the pressure. This pressure-induced transition to the glassy state is also accompanied by dramatic changes in the relaxation dynamics. Herein we discuss the behaviour of the structural relaxation times of glass-forming liquids and polymer melts under high pressure.

Effect of high pressure on the relaxation dynamics of glass-forming liquids

International Nuclear Information System (INIS)

Paluch, M; Grzybowska, K; Grzybowski, A

2007-01-01

A glass is usually formed by cooling a liquid at a rate sufficient to avoid crystallization. In the vicinity of the glass transition the structural relaxation time increases with lowering temperature in a non-Arrhenius fashion and the structural relaxation function reveals a non-Debye behaviour. However, liquid can be also vitrified by keeping it at a constant temperature and increasing the pressure. This pressure-induced transition to the glassy state is also accompanied by dramatic changes in the relaxation dynamics. Herein we discuss the behaviour of the structural relaxation times of glass-forming liquids and polymer melts under high pressure

Beta2-adrenoceptor-mediated tracheal relaxation induced by higenamine from Nandina domestica Thunberg.

Science.gov (United States)

Tsukiyama, Muneo; Ueki, Takuro; Yasuda, Yoichi; Kikuchi, Hiroko; Akaishi, Tatsuhiro; Okumura, Hidenobu; Abe, Kazuho

2009-10-01

The fruit of Nandina domestica Thunberg (ND, Berberidaceae) has been used to improve cough and breathing difficulties in Japan for many years, but very little is known about the constituent of ND responsible for this effect. We have recently reported that the crude extract from ND (NDE) inhibits histamine- and serotonin-induced contraction of isolated guinea pig trachea, and the inhibitory activity was not explained by nantenine, a well-known alkaloid isolated from ND. To explore other constituent(s) of NDE with tracheal smooth muscle relaxant activity, we fractionated NDE and assessed the pharmacological effects of the fractions using isolated guinea pig tracheal ring preparations. NDE was introduced into a polyaromatic absorbent resin column and stepwise eluted to yield five fractions, among which only the 40 % methanol fraction was active in relaxing tracheal smooth muscle precontracted with histamine. Further separation of the 40 % methanol fraction with high-performance liquid chromatography yielded multiple subfractions, one of which was remarkably active in relaxing histamine-precontracted trachea. Chemical analysis with a time-of-flight mass spectrometer and nuclear magnetic resonance spectrometer identified the constituent of the most active subfraction as higenamine, a benzyltetrahydroisoquinoline alkaloid. The potency and efficacy of the active constituent from NDE in relaxing trachea were almost equivalent to synthetic higenamine. In addition, the effect of the active constituent from NDE was competitively inhibited by the selective beta (2)-adrenoceptor antagonist ICI 118,551. These results indicate that the major constituent responsible for the effect of NDE is higenamine, which probably causes the tracheal relaxation through stimulation of beta (2) adrenoceptors. Georg Thieme Verlag KG Stuttgart-New York.

A comparison the effects of reflexology and relaxation on the psychological symptoms in women with multiple sclerosis.

Science.gov (United States)

Soheili, Mozhgan; Nazari, Fatemeh; Shaygannejad, Vahid; Valiani, Mahboobeh

2017-01-01

Multiple sclerosis (MS) occurs with a variety of physical and psychological symptoms, yet there is not a conclusive cure for this disease. Complementary medicine is a current treatment which seems is effective in relieving symptoms of patients with MS. Therefore, this study is aimed to determine and compare the effects of reflexology and relaxation on anxiety, stress, and depression in women with MS. This study is a randomized clinical trial that is done on 75 women with MS referred to MS Clinic of Kashani Hospital. After simple non random sampling, participants were randomly assigned by minimization method to three groups: reflexology, relaxation and control (25 patients in each group). In the experimental groups were performed reflexology and relaxation interventions within 4 weeks, twice a week for 40 min and the control group were received only routine treatment as directed by a doctor. Data were collected through depression anxiety and stress scale questionnaire, before, immediately after and 2 months after interventions in all three groups. Chi-square, Kruskal-Wallis, repeated measures analysis of variance and one-way analysis of variance and least significant difference post hoc test via SPSS version 18 were used to analyze the data ( P < 0.05) was considered as significant level. The results showed a significant reduction in the severity of anxiety, stress and depression during the different times in the reflexology and relaxation groups as compared with the control group ( P < 0.05). The results showed that reflexology and relaxation in relieving anxiety, stress and depression are effective in women with MS. Hence, these two methods, as effective techniques, can be recommended.

Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair.

Science.gov (United States)

Chang, Zhiwei; Halle, Bertil

2013-10-14

In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water (1)H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft

Non-linear finite element modelling and analysis of the effect of gasket creep-relaxation on circular bolted flange connections

International Nuclear Information System (INIS)

Luyt, P.C.B.; Theron, N.J.; Pietra, F.

2017-01-01

It is well known that gasket creep-relaxation results in a reduction of contact pressure between the surface of a gasket and the face of a flange over an extended period of time. This reduction may result in the subsequent failure of the circular bolted flange connection due to leakage. In this paper a pair of flat and raised face integral flanges, PN 10 DN 50 (in accordance with the European EN 1092-1 standard), with non-asbestos compressed fibre ring gaskets with aramid and a nitrile rubber binder were considered. Finite element modelling and analyses were done, for both the circular bolted flange configurations, during the seating condition. The results of the finite element analyses were experimentally validated. It was found that the number of bolt tightening increments as well as the time between the bolt tightening increments had a significant impact on the effect which gasket creep-relaxation had after the seating condition. An increase in either the number of bolting increments or the time between the bolting increments will reduce the effect which gasket creep-relaxation has once the bolts had been fastened. Based on these results it is possible to develop an optimisation scheme to minimize the effect which gasket creep-relaxation has on the contact pressure between the face of the flange and the gasket, after seating, by either increasing or decreasing the number of bolt tightening increments or the time between the bolt tightening increments. - Highlights: • Number of bolt tightening increments and time between bolt tightening increments had significant impact on effect of gasket creep-relaxation after the seating condition. • Impact of gasket creep-relaxation during seating and operating phases investigated by means of finite element analysis and experimentally verified. • Possible to develop optimisation scheme to minimize effect ofh gasket creep-relaxation on contact pressure between flange face and gasket. • Knowing the contact pressure is

Nitric oxide and catalase-sensitive relaxation by scutellarin in the mouse thoracic aorta.

Science.gov (United States)

Yang, Weimin; Lust, Robert M; Bofferding, April; Wingard, Christopher J

2009-01-01

The vascular activity of scutellarin (SCU), a flavonoid isolated from a Chinese traditional medicinal plant, was investigated in isolated thoracic aortic rings of mice. SCU-induced dose-dependent relaxation of phenylephrine (1 microM) stimulated contractions. This relaxation was reduced by endothelium removal, significantly reduced by both the nitric oxide synthase inhibitor (Nomega-nitro-L-arginine methylester, 300 microM) and slightly limited by the soluble guanylyl cyclase inhibitor (1 H-[1,2,4] oxidazolol [4,3-a] quinoxalin-1-one, 100 microM). The catalase inhibitor (3-amino-1,2,4-triazole, 50 mM) augmented the constriction and blocked the lowest SCU concentration relaxation, whereas catalase addition was without effect. Preincubation with 300 and 1000 microM SCU significantly suppressed the contractile dose-response to phenylephrine, causing both a significant rise in half maximal effective concentration and a decrease in the maximal developed force. Western blot analysis showed that SCU inhibition of contraction was independent of reductions in myosin light chain phosphorylation. These results suggested that SCU relaxation was predominantly endothelium dependent and likely involved the catalase-sensitive nitric oxide synthase signaling pathway, without loss of myosin phosphorylation. The potential clinical use of SCU may prove to be effective in increasing vasoreactivity, independently of smooth muscle contractile activity that is mediated by the 20-kDa myosin light chain phosphorylation.

Disentangling distribution effects and nature of the dynamics in relaxation measurements: the RMR method

CERN Document Server

Sappey, R; Ocio, M; Hammann, J

2000-01-01

We discuss here the nature of the low-temperature magnetic relaxation in samples of magnetic nanoparticles. In addition to usual magnetic viscosity measurement, we have used the residual memory ratio (RMR) method. This procedure enables us to overcome the uncertainties usually associated with the energy barrier distribution, thus giving a more detailed insight on the nature of the observed dynamics. A custom-made apparatus coupling dilution refrigeration and SQUID magnetometry allowed measurements of very diluted samples at temperatures ranging between 60 mK and 7 K. Two types of particles have been studied: gamma-Fe sub 2 O sub 3 of moderate anisotropy, and CoFe sub 2 O sub 4 of higher anisotropy where quantum effects are more likely to occur. In both cases, the data cannot simply be interpreted in terms of mere thermally activated dynamics of independent particles. The deviation from thermal activation seems to go opposite of what is expected from the possible effect of particle interactions. We therefore b...

Statistical mechanics of violent relaxation

International Nuclear Information System (INIS)

Shu, F.H.

1978-01-01

We reexamine the foundations of Lynden-Bell's statistical mechanical discussion of violent relaxation in collisionless stellar systems. We argue that Lynden-Bell's formulation in terms of a continuum description introduces unnecessary complications, and we consider a more conventional formulation in terms of particles. We then find the exclusion principle discovered by Lynden-Bell to be quantitatively important only at phase densities where two-body encounters are no longer negligible. Since the edynamical basis for the exclusion principle vanishes in such cases anyway, Lynden-Bell statistics always reduces in practice to Maxwell-Boltzmann statistics when applied to stellar systems. Lynden-Bell also found the equilibrium distribution function generally to be a sum of Maxwellians with velocity dispersions dependent on the phase density at star formation. We show that this difficulty vanishes in the particulate description for an encounterless stellar system as long as stars of different masses are initially well mixed in phase space. Our methods also demonstrate the equivalence between Gibbs's formalism which uses the microcanonical ensemble and Boltzmann's formalism which uses a coarse-grained continuum description. In addition, we clarify the concept of irreversible behavior on a macroscopic scale for an encounterless stellar system. Finally, we comment on the use of unusual macroscopic constraints to simulate the effects of incomplete relaxation

Cooling-history effects on magnetic relaxation through quantum tunneling

Science.gov (United States)

Fernandez, Julio; Alonso, Juan

2003-03-01

Magnetic clusters, such as Fe8 and Mn_12, that make up the core of large organometallic molecules, behave at low temperatures as large single spins S. In crystals, magnetic anisotropy energies U inhibit magnetic relaxation of these spins, which can then proceed at very small temperatures (at k_BT tunneling (MQT). Magnetic dipolar interactions then play an essential role. We study how an Ising system of spins that interact through magnetic dipolar fields relaxes. A spin is allowed to flip, at rate Γ, only if the magnetic field h acting on it is within some tunnel window -hw < h< h_w. We let (1) this system be initially held for some time at some temperature Ta that is above both the long-range ordering temperature and T ˜ U/S, and (2) apply a magnetic field at t=0, inmediately after the system is quenched to T < 0.1U/S. This is somewhat as in the experiments of Wernsdorfer et al on Fe_8. The time evolution of the magnetiztion m and field distributions after the field is applied at t=0 is studied. For small applied fields H, m ˜= hw HF(Γ t). In addition, F(Γ t)˜= cΓ t for Γ t < 1 and F(Γ t)˜= cΓ t for 1 <Γ t < (h_d/h_w)^2, where hd is a nearest neighbor dipolar field. We will show how c depends on the cooling protocol. Finally, m saturates at m_s˜= 0.13\\varepsilon_aH.

The effect of relaxation therapy on autonomic functioning, symptoms and daily functioning, in patients with chronic fatigue syndrome or fibromyalgia: a systematic review.

Science.gov (United States)

Meeus, Mira; Nijs, Jo; Vanderheiden, Tanja; Baert, Isabel; Descheemaeker, Filip; Struyf, Filip

2015-03-01

To establish the effects of relaxation therapy on autonomic function, pain, fatigue and daily functioning in patients with chronic fatigue syndrome or fibromyalgia. A systematic literature study was performed. Using specific keywords related to fibromyalgia or chronic fatigue syndrome and relaxation therapy, the electronic databases PubMed and Web of Science were searched. Included articles were assessed for their risk of bias and relevant information regarding relaxation was extracted. The review was conducted and reported according to the PRISMA-statement. Thirteen randomized clinical trials of sufficient quality were included, resulting in a total of 650 fibromyalgia patients (11 studies) and 88 chronic fatigue syndrome patients (3 studies). None of the studies reported effects on autonomic function. Six studies reported the effect of guided imagery on pain and daily functioning in fibromyalgia. The acute effect of a single session of guided imagery was studied in two studies and seems beneficial for pain relief. For other relaxation techniques (eg. muscle relaxation, autogenic training) no conclusive evidence was found for the effect on pain and functioning in fibromyalgia patients comparison to multimodal treatment programs. For fatigue a multimodal approach seemed better than relaxation, as shown in the sole three studies on chronic fatigue syndrome patients. There is moderate evidence for the acute effect of guided imagery on pain, although the content of the visualization is a matter of debate. Other relaxation formats and the effects on functionality and autonomic function require further study. © The Author(s) 2014.

Charge carrier relaxation model in disordered organic semiconductors

International Nuclear Information System (INIS)

Lu, Nianduan; Li, Ling; Sun, Pengxiao; Liu, Ming

2013-01-01

The relaxation phenomena of charge carrier in disordered organic semiconductors have been demonstrated and investigated theoretically. An analytical model describing the charge carrier relaxation is proposed based on the pure hopping transport theory. The relation between the material disorder, electric field and temperature and the relaxation phenomena has been discussed in detail, respectively. The calculated results reveal that the increase of electric field and temperature can promote the relaxation effect in disordered organic semiconductors, while the increase of material disorder will weaken the relaxation. The proposed model can explain well the stretched-exponential law by adopting the appropriate parameters. The calculation shows a good agreement with the experimental data for organic semiconductors

Stochastic model prediction of the Kovacs' ``expansion gap'' effect for volume relaxation in glassy polymers

Science.gov (United States)

Medvedev, Grigori; Caruthers, James

2015-03-01

The classic series of experiments by A. Kovacs on volume relaxation following temperature jumps for poly(vinyl acetate), PVAc, in the Tg region revealed the richness and complexity of the viscoelastic behavior of glassy materials. Over the years no theoretical model has been able to predict all the features of the Kovacs data, where the so-called ``expansion gap'' effect proved to be particularly challenging. Specifically, for a series of up-jump experiments with different initial temperatures, Ti, but with the same final temperature, as the relaxation approaches equilibrium it would be expected that the effective relaxation time would be the same regardless of Ti; however, Kovacs observed that the dependence on Ti persisted seemingly all the way to equilibrium. In this communication we will show that a recently developed Stochastic Constitutive Model (SCM) that explicitly acknowledges the nano-scale dynamic heterogeneity of glasses can capture the ``expansion gap'' as well as the rest of the Kovacs data set for PVAc. It will be shown that the success of the SCM is due to its inherent thermo-rheological complexity.

Relaxing music counters heightened consolidation of emotional memory.

Science.gov (United States)

Rickard, Nikki S; Wong, Wendy Wing; Velik, Lauren

2012-02-01

Emotional events tend to be retained more strongly than other everyday occurrences, a phenomenon partially regulated by the neuromodulatory effects of arousal. Two experiments demonstrated the use of relaxing music as a means of reducing arousal levels, thereby challenging heightened long-term recall of an emotional story. In Experiment 1, participants (N=84) viewed a slideshow, during which they listened to either an emotional or neutral narration, and were exposed to relaxing or no music. Retention was tested 1 week later via a forced choice recognition test. Retention for both the emotional content (Phase 2 of the story) and material presented immediately after the emotional content (Phase 3) was enhanced, when compared with retention for the neutral story. Relaxing music prevented the enhancement for material presented after the emotional content (Phase 3). Experiment 2 (N=159) provided further support to the neuromodulatory effect of music by post-event presentation of both relaxing music and non-relaxing auditory stimuli (arousing music/background sound). Free recall of the story was assessed immediately afterwards and 1 week later. Relaxing music significantly reduced recall of the emotional story (Phase 2). The findings provide further insight into the capacity of relaxing music to attenuate the strength of emotional memory, offering support for the therapeutic use of music for such purposes. Copyright © 2011 Elsevier Inc. All rights reserved.

Understanding Effect of Constraint Release Environment on End-to-End Vector Relaxation of Linear Polymer Chains

KAUST Repository

Shivokhin, Maksim E.

2017-05-30

We propose and verify methods based on the slip-spring (SSp) model [ Macromolecules 2005, 38, 14 ] for predicting the effect of any monodisperse, binary, or ternary environment of topological constraints on the relaxation of the end-to-end vector of a linear probe chain. For this purpose we first validate the ability of the model to consistently predict both the viscoelastic and dielectric response of monodisperse and binary mixtures of type A polymers, based on published experimental data. We also report the synthesis of new binary and ternary polybutadiene systems, the measurement of their linear viscoelastic response, and the prediction of these data by the SSp model. We next clarify the relaxation mechanisms of probe chains in these constraint release (CR) environments by analyzing a set of "toy" SSp models with simplified constraint release rates, by examining fluctuations of the end-to-end vector. In our analysis, the longest relaxation time of the probe chain is determined by a competition between the longest relaxation times of the effective CR motions of the fat and thin tubes and the motion of the chain itself in the thin tube. This picture is tested by the analysis of four model systems designed to separate and estimate every single contribution involved in the relaxation of the probe\\'s end-to-end vector in polydisperse systems. We follow the CR picture of Viovy et al. [ Macromolecules 1991, 24, 3587 ] and refine the effective chain friction in the thin and fat tubes based on Read et al. [ J. Rheol. 2012, 56, 823 ]. The derived analytical equations form a basis for generalizing the proposed methodology to polydisperse mixtures of linear and branched polymers. The consistency between the SSp model and tube model predictions is a strong indicator of the compatibility between these two distinct mesoscopic frameworks.

Cyanide and sulfide interact with nitrogenous compounds to influence the relaxation of various smooth muscles

Energy Technology Data Exchange (ETDEWEB)

Kruszyna, H.; Kruszyna, R.; Smith, R.P.

1985-05-01

Sodium nitroprusside relaxed guinea pig ileum after the segment had been submaximally contracted by either histamine or acetylcholine, intact isolated rabbit gall bladder after submaximal contraction by either acetylcholine or cholecystokinin octapeptide, and rat pulmonary artery helical strips after submaximal contraction with norepinephrine. In each of these cases the relaxation produced by nitroprusside was at least partially reversed by the subsequent addition of excess sodium cyanide. Cyanide, however, in nontoxic concentrations did not reverse the spasmolytic effects of hydroxylamine hydrochloride, sodium azide, nitroglycerin, sodium nitrite, or nitric oxide hemoglobin on guinea pig ileum, nor did cyanide alone in the same concentrations have any effect. The similar interaction between nitroprusside and cyanide on rabbit aortic strips is not dependent on the presence of an intact endothelia cell layer. Also, on rabbit aortic strips and like cyanide, sodium sulfide reversed the spasmolytic effects of azide and hydroxylamine, but it had little or no effect on the relaxation induced by papaverine. Unlike cyanide, however, sulfide augmented the relaxation induced by nitroprusside, and it reversed the effects of nitric oxide hemoglobin, nitroglycerin, and nitrite. A direct chemical reaction between sulfide and nitroprusside may account for the difference between it and cyanide. Although evidence was obtained also for a direct chemical reaction between sulfide and norepinephrine, that reaction does not seem to have played a role in these results.

Airway Relaxation Effects of Water-Soluble Sclerotial Extract From Lignosus rhinocerotis

Directory of Open Access Journals (Sweden)

Mei Kee Lee

2018-05-01

Full Text Available Lignosus rhinocerotis has a long history of use by the indigenous community within East Asia to treat a range of health conditions including asthma and chronic cough. To date, there is limited scientific evidence to support its therapeutic effects in relieving these airways conditions. In this study, we examined the effects of the different molecular weight fractions [high-molecular-weight (HMW, medium-molecular-weight (MMW, and low-molecular-weight (LMW] obtained from the cold water sclerotial extract (CWE of L. rhinocerotis on airways patency using airway segments isolated from Sprague Dawley rat in an organ bath set-up. It is demonstrated that the HMW and MMW fractions exhibited higher efficacy in relaxing the pre-contracted airways when compared to the CWE and LMW fraction. In addition, the HMW fraction markedly supressed carbachol-, 5-hydroxytrptamine-, and calcium-induced airway contractions. CWE demonstrated a lower efficacy than the HMW fraction but it also significantly attenuated carbachol- and calcium-induced airway contractions. Results showed that the bronchorelaxation effect of CWE and fractions is mediated via blockade of extracellular Ca2+ influx. The composition analysis revealed the following parts of carbohydrate and proteins, respectively: HMW fraction: 71 and 4%; MMW fraction: 35 and 1%; and LMW fraction: 22 and 0.3%. Our results strongly suggest that the polysaccharide–protein complex or proteins found in the HMW and MMW fractions is likely to contribute to the bronchorelaxation effect of CWE.

Relaxation characteristics of hastelloy X

International Nuclear Information System (INIS)

Suzuki, Kazuhiko

1980-02-01

Relaxation diagrams of Hastelloy X (relaxation curves, relaxation design diagrams, etc.) were generated from the creep constitutive equation of Hastelloy X, using inelastic stress analysis code TEPICC-J. These data are in good agreement with experimental relaxation data of ORNL-5479. Three typical inelastic stress analyses were performed for various relaxation behaviors of the high-temperature structures. An attempt was also made to predict these relaxation behaviors by the relaxation curves. (author)

Tracheal epithelium cell volume responses to hyperosmolar, isosmolar and hypoosmolar solutions: relation to epithelium-derived relaxing factor (EpDRF effects

Directory of Open Access Journals (Sweden)

Jeffrey S. Fedan

2013-10-01

Full Text Available In asthmatic patients, inhalation of hyperosmolar saline or D-mannitol (D-M elicits bronchoconstriction, but in healthy subjects exercise causes bronchodilation. Hyperventilation causes drying of airway surface liquid (ASL and increases its osmolarity. Hyperosmolar challenge of airway epithelium releases epithelium-derived relaxing factor (EpDRF, which relaxes the airway smooth muscle. This pathway could be involved in exercise-induced bronchodilation. Little is known of ASL hyperosmolarity effects on epithelial function. We investigated the effects of osmolar challenge maneuvers on dispersed and adherent guinea-pig tracheal epithelial cells to examine the hypothesis that EpDRF-mediated relaxation is associated with epithelial cell shrinkage. Enzymatically-dispersed cells shrank when challenged with ≥10 mOsM added D M, urea or NaCl with a concentration-dependence that mimics relaxation of the of isolated, perfused tracheas (IPT. Cells shrank when incubated in isosmolar N-methyl-D-glucamine (NMDG chloride, Na gluconate (Glu, NMDG-Glu, K-Glu and K2SO4, and swelled in isosmolar KBr and KCl. However, isosmolar challenge is not a strong stimulus of relaxation in IPTs. In previous studies amiloride and 4,4' diisothiocyano 2,2' stilbenedisulfonic acid (DIDS inhibited relaxation of IPT to hyperosmolar challenge, but had little effect on shrinkage of dispersed cells. Confocal microscopy in tracheal segments showed that adherent epithelium is refractory to low hyperosmolar concentrations that induce dispersed cell shrinkage and relaxation of IPT. Except for gadolinium and erythro 9 (2 hydroxy 3 nonyladenine (EHNA, actin and microtubule inhibitors and membrane permeabilizing agents did not affect on ion transport by adherent epithelium or shrinkage responses of dispersed cells. Our studies dissociate relaxation of IPT from cell shrinkage after hyperosmolar challenge of airway epithelium .

Corroborative evidences of TV γ -scaling of the α-relaxation originating from the primitive relaxation/JG β relaxation

Science.gov (United States)

Ngai, K. L.; Paluch, M.

2017-12-01

Successful thermodynamic scaling of the structural alpha-relaxation time or transport coefficients of glass-forming liquids determined at various temperatures T and pressures P means the data conform to a single function of the product variable TVgamma, where V is the specific volume and gamma is a material specific constant. In the past two decades we have witnessed successful TVgamma-scaling in many molecular, polymeric, and even metallic glass-formers, and gamma is related to the slope of the repulsive part of the intermolecular potential. The advances made indicate TVgamma-scaling is an important aspect of the dynamic and thermodynamic properties of glass-formers. In this paper we show the origin of TVgamma-scaling is not from the structural alpha-relaxation time. Instead it comes from its precursor, the Johari-Goldstein beta-relaxation or the primitive relaxation of the Coupling Model and their relaxation times or tau_0 respectively. It is remarkable that all relaxation times are functions of TVgamma with the same gama, as well as the fractional exponent of the Kohlrausch correlation function of the structural alpha-relaxation. We arrive at this conclusion convincingly based on corroborative evidences from a number of experiments and molecular dynamics simulations performed on a wide variety of glass-formers and in conjunction with consistency with the predictions of the Coupling Model.

Constraints on relaxation rates for N-level quantum systems

International Nuclear Information System (INIS)

Schirmer, S.G.; Solomon, A.I.

2004-01-01

We study the constraints imposed on the population and phase relaxation rates by the physical requirement of completely positive evolution for open N-level systems. The Lindblad operators that govern the evolution of the system are expressed in terms of observable relaxation rates, explicit formulas for the decoherence rates due to population relaxation are derived, and it is shown that there are additional, nontrivial constraints on the pure dephasing rates for N>2. Explicit, experimentally testable inequality constraints for the decoherence rates are derived for three- and four-level systems, and the implications of the results are discussed for generic ladder, Λ, and V systems and transitions between degenerate energy levels

Isotopic and chemical dilution effects on the vibrational relaxation rate of some totally symmetric motions of liquid acetonitrile

International Nuclear Information System (INIS)

Marri, E.; Morresi, A.; Paliani, G.; Cataliotti, R.S.; Giorgini, M.G.

1999-01-01

The vibrational dephasing of the ν 1 (C-H, C-D stretching) and ν 3 (C-H, C-D bending) symmetric motions of liquid acetonitrile in its light and fully deuterated forms has been studied in the frame of the vibrational time correlation functions obtained as Fourier transforms of the isotropic Raman spectral distributions and interpreted within the Kubo theory. In addition, the experimental isotropic profiles have been analysed within the bandshape approach formulated by analytical Fourier transformation of the Kubo vibrational time correlation functions in order to derive the relaxation parameters in the frequency domain. The effects of the isotopic (CH 3 CN/CD 3 CN and vice versa) and chemical (CCl 4 ) dilution on the bandshapes and on the vibrational relaxation parameters have been studied. It was observed that the decay rate of ν 1 mode is insensitive to the isotopic dilution but varies appreciably with chemical (CCl 4 ) dilution. The vibrational dephasing of ν 3 mode is qualitatively, but not quantitatively, affected in the same way by chemical dilution and shows a slower modulation regime than that exhibited by the stretching mode. Unlikely from the latter, the ν 3 mode results are slightly affected by the isotopic dilution. Phase relaxation mechanisms of these two motions of acetonitrile in the liquid state are proposed on the basis of these data, and a comparison is made with the results earlier published. (Copyright (c) 1999 Elsevier Science B.V., Amsterdam. All rights reserved.)

Resonances in field-cycling NMR on molecular crystals. (reversible) Spin dynamics or (irreversible) relaxation?; Resonanzen in Field-Cycling-NMR an Molekuelkristallen. (reversible) Spindynamik oder (irreversible) Relaxation?

Energy Technology Data Exchange (ETDEWEB)

Tacke, Christian

2015-07-01

Multi spin systems with spin 1/2 nuclei and dipolar coupled quadrupolar nuclei can show so called ''quadrupolar dips''. There are two main reasons for this behavior: polarization transfer and relaxation. They look quite alike and without additional research cannot be differentiated easily in most cases. These two phenomena have quite different physical and theoretical backgrounds. For no or very slow dynamics, polarization transfer will take place, which is energy conserving inside the spin system. This effect can entirely be described using quantum mechanics on the spin system. Detailed knowledge about the crystallography is needed, because this affects the relevant hamiltonians directly. For systems with fast enough dynamics, relaxation takes over, and the energy flows from the spin system to the lattice; thus a more complex theoretical description is needed. This description has to include a dynamic model, usually in the form of a spectral density function. Both models should include detailed modelling of the complete spin system. A software library was developed to be able to model complex spin systems. It allows to simulate polarization transfer or relaxation effects. NMR measurements were performed on the protonic conductor K{sub 3}H(SO{sub 4}){sub 2}. A single crystal shows sharp quadrupolar dips at room temperature. Dynamics could be excluded using relaxation measurements and literature values. Thus, a polarization transfer analysis was used to describe those dips with good agreement. As a second system, imidazolium based molecular crystals were analyzed. The quadrupolar dips were expected to be caused by polarization transfer; this was carefully analyzed and found not to be true. A relaxation based analysis shows good agreement with the measured data in the high temperature area. It leverages a two step spectral density function, which indicates two distinct dynamic processes happening in this system.

13C spin relaxation measurements in RNA: Sensitivity and resolution improvement using spin-state selective correlation experiments

International Nuclear Information System (INIS)

Boisbouvier, Jerome; Brutscher, Bernhard; Simorre, Jean-Pierre; Marion, Dominique

1999-01-01

A set of new NMR pulse sequences has been designed for the measurement of 13 C relaxation rate constants in RNA and DNA bases: the spin-lattice relaxation rate constant R(C z ), the spin-spin relaxation rate constant R(C + ), and the CSA-dipolar cross-correlated relaxation rate constant Γ C,CH xy . The use of spin-state selective correlation techniques provides increased sensitivity and spectral resolution. Sensitivity optimised C-C filters are included in the pulse schemes for the suppression of signals originating from undesired carbon isotopomers. The experiments are applied to a 15% 13 C-labelled 33-mer RNA-theophylline complex. The measured R(C + )/Γ C,CH xy ratios indicate that 13 C CSA tensors do not vary significantly for the same type of carbon (C 2 , C 6 , C 8 ), but that they differ from one type to another. In addition, conformational exchange effects in the RNA bases are detected as a change in the relaxation decay of the narrow 13 C doublet component when varying the spacing of a CPMG pulse train. This new approach allows the detection of small exchange effects with a higher precision compared to conventional techniques

Modelling Creep (Relaxation of the Urinary Bladder

Directory of Open Access Journals (Sweden)

Zdravkovic Nebojsa

2017-12-01

Full Text Available We first present the results of an experiment in which the passive properties of the urinary bladder were investigated using strips of rabbit bladder. Under the assumption that the urinary bladder had orthopaedic characteristics, the strips were taken in the longitudinal and in the circumferential directions. The material was subjected to uniaxial tension, and stress-stretch curves were generated for various rates of deformation. We found that the rates did not have a significantly effect on the passive response of the material. Additionally, the stress-stretch dependence during relaxation of the material when exposed to isometric conditions was determined experimentally.

The relaxational behaviour of poly-(vinylidene fluoride) before and after gamma-irradiation

International Nuclear Information System (INIS)

Callens, A.

The main purpose of this work was to investigate how molecular chain reorganization may affect the physical property of polymers. This may be done by the analysis of the as received and post-irradiation relaxation spectra of the semi-crystalline linear chain polymer polyvinylidene fluoride (PVDF), which has been gamma-irradiated up to doses of 1 grad. The effects of the irradiation on the material are primarly main chain cross-linking production of unsaturated bonds and crystallite degradation. To reach a complete interpretation of the relaxation spectra, it is necessary to incorporate a third phase into the analysis besides the amorphous viscoelastic region (AVR) and the crystalline viscoelastic region (CVR), the intermediate phase. The amorphous phase (AVR) is at the origin of the relaxation effects occurring in the temperature region below room temperature. The saturation like behaviour of the cross-linking in the amorphous phase is at the origin of the intensity decrease, temperature shift and peak broadening of the beta relaxation. There is a large amount of evidence that in the neighbourhood of the beta relaxation, relaxation effects are created through irradiation, as mainly revealed by TSD-spectra (thermalloy stimulated depolarisation). The intensity of the gamma relaxation, gradually increases with dose, which has been attributed to the production of disordered chain from the debris of radiation enhanced crystallite destruction. The relaxation effect, occuring at the temperatures between AVR and CVR, is assigned to the long amorphous chain segments attached partly to the crystallites, mainly from the consideration of the similarity of the dose enhanced decrease in intensity of both beta and βsub(μ)-effects. The increase with dose of the intensity of the α1 relaxation, which has been classified within CVR, confirms the grainboundary hypothesis. The second component of CVR (α2 relaxation) is due to relaxation effects of molecular chains belonging to the

Characterization of structural relaxation in inorganic glasses using length dilatometry

Science.gov (United States)

Koontz, Erick

low temperature state with many relaxations to a high temperature state with only a single relaxation. Evidence was found for the existence of a definitive transition of some kind in the range of Tg possibly relating the idea of a percolation temperature (T*) as defined by Carmi. The results of the measurements showed substantial support for both the Adam-Gibbs interpretation of decreasing entropy towards the Kauzmann temperature, while also displaying trends compatible with energy landscape theory and the idea of broken ergodicity of glass configuration below Tg. In addition effective relaxation energies were calculated and the energy needed for relaxation showed a definite upward trend with decreasing temperature also supporting the idea of reduced entropy and configurational freedom at lower temperatures. The effective relaxation energies are not purely thermodynamic in nature because they also characterize the effects of viscosity and the kinetics of the material that was relaxing. (Abstract shortened by UMI.).

Relaxant effect of the ethanol extract of Helichrysum plicatum (Asteraceae) on isolated rat ileum contractions.

Science.gov (United States)

Bigovic, Dubravka; Brankovic, Suzana; Kitic, Dusanka; Radenkovic, Mirjana; Jankovic, Teodora; Savikin, Katarina; Zivanovic, Slavoljub

2010-05-10

Helichrysum plicatum (Turkish Helichrysum) has been used in folk medicine for the treatment of gastric and hepatic disorders. The aim of the present study was to examine the relaxant activity of an extract of H. plicatum flowers on isolated rat ileum. Segments of ileum of rats were suspended in an organ bath. Cumulative concentrations of H. plicatum ethanol extract induced a relaxant effect on spontaneous rat ileum contractions. H. plicatum extract caused a mean contractile response of 81.68 +/- 6.17% (at a dose of 0.01 mg/mL) and 30.08 +/- 9.07% (at a dose of 1 mg/mL). A similar effect was observed with papaverine (0.01-3 microg/mL). H. plicatum extract (0.01-1 mg/mL) relaxed high K+ (80 mM) precontractions, an effect similar to that caused by papaverine (0.01-3 microg/mL). The plant extract (0.03-0.3 mg/mL) also induced a significant depression of the cumulative concentration response curve for acetylcholine (5-1500 nM) (p Helichrysum plicatum flowers on the isolated rat intestine Extract of H. plicatum can inhibit the spontaneous ileum contractions and contractions induced by acetylcholine, histamine, barium and potassium ions.

Effect of the Magnus force on skyrmion relaxation dynamics

Science.gov (United States)

Brown, Barton L.; Täuber, Uwe C.; Pleimling, Michel

2018-01-01

We perform systematic Langevin molecular dynamics simulations of interacting skyrmions in thin films. The interplay between the Magnus force, the repulsive skyrmion-skyrmion interaction, and the thermal noise yields different regimes during nonequilibrium relaxation. In the noise-dominated regime, the Magnus force enhances the disordering effects of the thermal noise. In the Magnus-force-dominated regime, the Magnus force cooperates with the skyrmion-skyrmion interaction to yield a dynamic regime with slow decaying correlations. These two regimes are characterized by different values of the aging exponent. In general, the Magnus force accelerates the approach to the steady state.

A computational study of inviscid hypersonic flows using energy relaxation method

International Nuclear Information System (INIS)

Nagdewe, Suryakant; Kim, H. D.; Shevare, G. R.

2008-01-01

Reasonable analysis of hypersonic flows requires a thermodynamic non-equilibrium model to properly simulate strong shock waves or high pressure and temperature states in the flow field. The energy relaxation method (ERM) has been used to model such a non-equilibrium effect which is generally expressed as a hyperbolic system of equations with a stiff relaxation source term. Relaxation time that is multiplied with source terms is responsible for nonequilibrium in the system. In the present study, a numerical analysis has been carried out with varying values of relaxation time for several hypersonic flows with AUSM (advection upstream splitting method) as a numerical scheme. Vibration modes of thermodynamic nonequilibrium effects are considered. The results obtained showed that, as the relaxation time reduces to zero, the solution marches toward equilibrium, while it shows non-equilibrium effects, as the relaxation time increases. The present computations predicted the experiment results of hypersonic flows with good accuracy. The work carried out suggests that the present energy relaxation method can be robust for analysis of hypersonic flows

Proton T2 Relaxation effect of superparamagnetic iron oxide on fast spin echo sequence. Influence of echo number (even or odd) of effective TE

International Nuclear Information System (INIS)

Tsuchihashi, Toshio; Maki, Toshio; Kitagawa, Matsuo; Suzuki, Takeshi; Fujita, Isao

1999-01-01

The T 2 relaxation effect of the fast spin echo sequence (FSE) was investigated using superparamagnetic iron oxide (SPIO) particles. When even echoes were used as the effective TE of FSE, the signal intensity ratio [signal intensity of FSE/signal intensity of conventional spin echo sequence (CSE)] of FSE and CSE increased, whereas the T 2 relaxation effect of SPIO with FSE was reduced. However, when odd echoes were used, neither signal intensity changed, and weakening of the T 2 relaxation effect, considered a problem with FSE, was reduced. This phenomenon was not observed when the refocusing flip angle was changed to 30 and 60 degrees. However, it was observed when the refocusing flip angle was 120 and 150 degrees. Thus, this phenomenon can be considered to be related to oscillation in longitudinal magnetization when using the Carr-Purcell-Meiboom-Gill (CPMG) technique. (author)

Arresting relaxation in Pickering Emulsions

Science.gov (United States)

Atherton, Tim; Burke, Chris

2015-03-01

Pickering emulsions consist of droplets of one fluid dispersed in a host fluid and stabilized by colloidal particles absorbed at the fluid-fluid interface. Everyday materials such as crude oil and food products like salad dressing are examples of these materials. Particles can stabilize non spherical droplet shapes in these emulsions through the following sequence: first, an isolated droplet is deformed, e.g. by an electric field, increasing the surface area above the equilibrium value; additional particles are then adsorbed to the interface reducing the surface tension. The droplet is then allowed to relax toward a sphere. If more particles were adsorbed than can be accommodated by the surface area of the spherical ground state, relaxation of the droplet is arrested at some non-spherical shape. Because the energetic cost of removing adsorbed colloids exceeds the interfacial driving force, these configurations can remain stable over long timescales. In this presentation, we present a computational study of the ordering present in anisotropic droplets produced through the mechanism of arrested relaxation and discuss the interplay between the geometry of the droplet, the dynamical process that produced it, and the structure of the defects observed.

Spin relaxation in nanowires by hyperfine coupling

International Nuclear Information System (INIS)

Echeverria-Arrondo, C.; Sherman, E.Ya.

2012-01-01

Hyperfine interactions establish limits on spin dynamics and relaxation rates in ensembles of semiconductor quantum dots. It is the confinement of electrons which determines nonzero hyperfine coupling and leads to the spin relaxation. As a result, in nanowires one would expect the vanishing of this effect due to extended electron states. However, even for relatively clean wires, disorder plays a crucial role and makes electron localization sufficient to cause spin relaxation on the time scale of the order of 10 ns. (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Topology Synthesis of Structures Using Parameter Relaxation and Geometric Refinement

Science.gov (United States)

Hull, P. V.; Tinker, M. L.

2007-01-01

Typically, structural topology optimization problems undergo relaxation of certain design parameters to allow the existence of intermediate variable optimum topologies. Relaxation permits the use of a variety of gradient-based search techniques and has been shown to guarantee the existence of optimal solutions and eliminate mesh dependencies. This Technical Publication (TP) will demonstrate the application of relaxation to a control point discretization of the design workspace for the structural topology optimization process. The control point parameterization with subdivision has been offered as an alternative to the traditional method of discretized finite element design domain. The principle of relaxation demonstrates the increased utility of the control point parameterization. One of the significant results of the relaxation process offered in this TP is that direct manufacturability of the optimized design will be maintained without the need for designer intervention or translation. In addition, it will be shown that relaxation of certain parameters may extend the range of problems that can be addressed; e.g., in permitting limited out-of-plane motion to be included in a path generation problem.

Relaxed plasma-vacuum systems

International Nuclear Information System (INIS)

Spies, G.O.; Lortz, D.; Kaiser, R.

2001-01-01

Taylor's theory of relaxed toroidal plasmas (states of lowest energy with fixed total magnetic helicity) is extended to include a vacuum between the plasma and the wall. In the extended variational problem, one prescribes, in addition to the helicity and the magnetic fluxes whose conservation follows from the perfect conductivity of the wall, the fluxes whose conservation follows from the assumption that the plasma-vacuum interface is also perfectly conducting (if the wall is a magnetic surface, then one has the toroidal and the poloidal flux in the vacuum). Vanishing of the first energy variation implies a pressureless free-boundary magnetohydrostatic equilibrium with a Beltrami magnetic field in the plasma, and in general with a surface current in the interface. Positivity of the second variation implies that the equilibrium is stable according to ideal magnetohydrodynamics, that it is a relaxed state according to Taylor's theory if the interface is replaced by a wall, and that the surface current is nonzero (at least if there are no closed magnetic field lines in the interface). The plane slab, with suitable boundary conditions to simulate a genuine torus, is investigated in detail. The relaxed state has the same double symmetry as the vessel if, and only if, the prescribed helicity is in an interval that depends on the prescribed fluxes. This interval is determined in the limit of a thin slab

Strain modulations as a mechanism to reduce stress relaxation in laryngeal tissues.

Science.gov (United States)

Hunter, Eric J; Siegmund, Thomas; Chan, Roger W

2014-01-01

Vocal fold tissues in animal and human species undergo deformation processes at several types of loading rates: a slow strain involved in vocal fold posturing (on the order of 1 Hz or so), cyclic and faster posturing often found in speech tasks or vocal embellishment (1-10 Hz), and shear strain associated with vocal fold vibration during phonation (100 Hz and higher). Relevant to these deformation patterns are the viscous properties of laryngeal tissues, which exhibit non-linear stress relaxation and recovery. In the current study, a large strain time-dependent constitutive model of human vocal fold tissue is used to investigate effects of phonatory posturing cyclic strain in the range of 1 Hz to 10 Hz. Tissue data for two subjects are considered and used to contrast the potential effects of age. Results suggest that modulation frequency and extent (amplitude), as well as the amount of vocal fold overall strain, all affect the change in stress relaxation with modulation added. Generally, the vocal fold cover reduces the rate of relaxation while the opposite is true for the vocal ligament. Further, higher modulation frequencies appear to reduce the rate of relaxation, primarily affecting the ligament. The potential benefits of cyclic strain, often found in vibrato (around 5 Hz modulation) and intonational inflection, are discussed in terms of vocal effort and vocal pitch maintenance. Additionally, elderly tissue appears to not exhibit these benefits to modulation. The exacerbating effect such modulations may have on certain voice disorders, such as muscle tension dysphonia, are explored.

Strain modulations as a mechanism to reduce stress relaxation in laryngeal tissues.

Directory of Open Access Journals (Sweden)

Eric J Hunter

Full Text Available Vocal fold tissues in animal and human species undergo deformation processes at several types of loading rates: a slow strain involved in vocal fold posturing (on the order of 1 Hz or so, cyclic and faster posturing often found in speech tasks or vocal embellishment (1-10 Hz, and shear strain associated with vocal fold vibration during phonation (100 Hz and higher. Relevant to these deformation patterns are the viscous properties of laryngeal tissues, which exhibit non-linear stress relaxation and recovery. In the current study, a large strain time-dependent constitutive model of human vocal fold tissue is used to investigate effects of phonatory posturing cyclic strain in the range of 1 Hz to 10 Hz. Tissue data for two subjects are considered and used to contrast the potential effects of age. Results suggest that modulation frequency and extent (amplitude, as well as the amount of vocal fold overall strain, all affect the change in stress relaxation with modulation added. Generally, the vocal fold cover reduces the rate of relaxation while the opposite is true for the vocal ligament. Further, higher modulation frequencies appear to reduce the rate of relaxation, primarily affecting the ligament. The potential benefits of cyclic strain, often found in vibrato (around 5 Hz modulation and intonational inflection, are discussed in terms of vocal effort and vocal pitch maintenance. Additionally, elderly tissue appears to not exhibit these benefits to modulation. The exacerbating effect such modulations may have on certain voice disorders, such as muscle tension dysphonia, are explored.

Investigation of effective impact parameters in electron-ion temperature relaxation via Particle-Particle Coulombic molecular dynamics

Science.gov (United States)

Zhao, Yinjian

2017-09-01

Aiming at a high simulation accuracy, a Particle-Particle (PP) Coulombic molecular dynamics model is implemented to study the electron-ion temperature relaxation. In this model, the Coulomb's law is directly applied in a bounded system with two cutoffs at both short and long length scales. By increasing the range between the two cutoffs, it is found that the relaxation rate deviates from the BPS theory and approaches the LS theory and the GMS theory. Also, the effective minimum and maximum impact parameters (bmin* and bmax*) are obtained. For the simulated plasma condition, bmin* is about 6.352 times smaller than the Landau length (bC), and bmax* is about 2 times larger than the Debye length (λD), where bC and λD are used in the LS theory. Surprisingly, the effective relaxation time obtained from the PP model is very close to the LS theory and the GMS theory, even though the effective Coulomb logarithm is two times greater than the one used in the LS theory. Besides, this work shows that the PP model (commonly known as computationally expensive) is becoming practicable via GPU parallel computing techniques.

Giant deviation of a relaxation time from generalized Newtonian theory in discontinuous shear thickening suspensions

Science.gov (United States)

Maharjan, Rijan; Brown, Eric

2017-12-01

We investigated the transient relaxation of a discontinuous shear thickening (DST) suspension of cornstarch in water. We performed two types of relaxation experiments starting from a steady shear in a parallel-plate rheometer, followed either by stopping the top plate rotation and measuring the transient torque relaxation or by removing the torque on the plate and measuring the transient rotation of the tool. We found that at low effective weight fraction ϕeffmodel. The regime where the relaxation was inconsistent with the generalized Newtonian model was the same where we found positive normal stress during relaxation, and in some cases we found an oscillatory response, suggestive of a solidlike structure consisting of a system-spanning contact network of particles. This regime also corresponds to the same packing fraction range where we consistently found discontinuous shear thickening in rate-controlled, steady-state measurements. The relaxation time in this range scales with the inverse of the critical shear rate at the onset of shear thickening, which may correspond to a contact relaxation time for nearby particles in the structure to flow away from each other. In this range, the relaxation time was the same in both stress- and rate-controlled relaxation experiments, indicating the relaxation time is more intrinsic than an effective viscosity in this range and is needed in addition to the steady-state viscosity function to describe transient flows. The discrepancy between the measured relaxation times and the generalized Newtonian prediction was found to be as large as four orders of magnitude, and extrapolations diverge in the limit as ϕeff→ϕc as the generalized Newtonian prediction approaches 0. This quantitative discrepancy indicates the relaxation is not controlled by the dissipative terms in the constitutive relation. At the highest weight fractions, the relaxation time scales were measured to be on the order of ˜1 s. The fact that this time scale is

Thermally-induced electronic relaxation in structurally-modified Cu0.1Ni0.8Co0.2Mn1.9O4 spinel ceramics

International Nuclear Information System (INIS)

Shpotyuk, O.; Balitska, V.; Brunner, M.; Hadzaman, I.; Klym, H.

2015-01-01

Thermally-induced electronic relaxation in structurally-modified Cu 0.1 Ni 0.8 Co 0.2 Mn 1.9 O 4 spinel ceramics is shown to be adequately described by stretched exponential function on time. This kinetics is defined by microsctructure perfectness of the relaxing media, showing obvious onset to stretched exponential behaviour with non-exponentionality index attaining close to 0.43 values for high-monolith ceramics and smaller ones in fine-grained ceramics. Percolation threshold in relaxation-degradation kinetics is detected for ceramics with 10% of NiO extractions, showing the smallest but most prolonged single-path degradation effect. This finding is treated in terms of Phillips’ axiomatic diffusion-to-trap model, where only one of two relaxation channels (caused by operative short-range forces) occurs to be effective, while additional non-operative channels contribute to electronic relaxation in fine-grained ceramics

A new method for studying the structure relaxation of amorphous matters

International Nuclear Information System (INIS)

Cao Xiaowen

1989-11-01

A new method for studying the structure relaxation of amorphous matters by Hall effect is proposed. The structure relaxation of the metal-type amorphous InSb has been experimentally studied. The experimental results show that this method is highly sensitive to the structure relaxation, and the mechanism of structure relaxation can be observed

A wrinkling-based method for investigating glassy polymer film relaxation as a function of film thickness and temperature.

Science.gov (United States)

Chung, Jun Young; Douglas, Jack F; Stafford, Christopher M

2017-10-21

We investigate the relaxation dynamics of thin polymer films at temperatures below the bulk glass transition T g by first compressing polystyrene films supported on a polydimethylsiloxane substrate to create wrinkling patterns and then observing the slow relaxation of the wrinkled films back to their final equilibrium flat state by small angle light scattering. As with recent relaxation measurements on thin glassy films reported by Fakhraai and co-workers, we find the relaxation time of our wrinkled films to be strongly dependent on film thickness below an onset thickness on the order of 100 nm. By varying the temperature between room temperature and T g (≈100 °C), we find that the relaxation time follows an Arrhenius-type temperature dependence to a good approximation at all film thicknesses investigated, where both the activation energy and the relaxation time pre-factor depend appreciably on film thickness. The wrinkling relaxation curves tend to cross at a common temperature somewhat below T g , indicating an entropy-enthalpy compensation relation between the activation free energy parameters. This compensation effect has also been observed recently in simulated supported polymer films in the high temperature Arrhenius relaxation regime rather than the glassy state. In addition, we find that the film stress relaxation function, as well as the height of the wrinkle ridges, follows a stretched exponential time dependence and the short-time effective Young's modulus derived from our modeling decreases sigmoidally with increasing temperature-both characteristic features of glassy materials. The relatively facile nature of the wrinkling-based measurements in comparison to other film relaxation measurements makes our method attractive for practical materials development, as well as fundamental studies of glass formation.

Universal binding energy relation for cleaved and structurally relaxed surfaces.

Science.gov (United States)

Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V

2014-02-05

The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress-displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements.

Effect of substrate rotation on domain structure and magnetic relaxation in magnetic antidot lattice arrays

International Nuclear Information System (INIS)

Mallick, Sougata; Mallik, Srijani; Bedanta, Subhankar

2015-01-01

Microdimensional triangular magnetic antidot lattice arrays were prepared by varying the speed of substrate rotation. The pre-deposition patterning has been performed using photolithography technique followed by a post-deposition lift-off. Surface morphology taken by atomic force microscopy depicted that the growth mechanism of the grains changes from chain like formation to island structures due to the substrate rotation. Study of magnetization reversal via magneto optic Kerr effect based microscopy revealed reduction of uniaxial anisotropy and increase in domain size with substrate rotation. The relaxation measured under constant magnetic field becomes faster with rotation of the substrate during deposition. The nature of relaxation for the non-rotating sample can be described by a double exponential decay. However, the relaxation for the sample with substrate rotation is well described either by a double exponential or a Fatuzzo-Labrune like single exponential decay, which increases in applied field

Relaxation training after stroke: potential to reduce anxiety.

Science.gov (United States)

Kneebone, Ian; Walker-Samuel, Natalie; Swanston, Jennifer; Otto, Elisabeth

2014-01-01

To consider the feasibility of setting up a relaxation group to treat symptoms of post stroke anxiety in an in-patient post-acute setting; and to explore the effectiveness of relaxation training in reducing self-reported tension. A relaxation group protocol was developed in consultation with a multidisciplinary team and a user group. Over a period of 24 months, 55 stroke patients attended group autogenic relaxation training on a rehabilitation ward. Attendance ranged between one and eleven sessions. Self-reported tension was assessed pre and post relaxation training using the Tension Rating Circles (TRCs). The TRCs identified a significant reduction in self-reported tension from pre to post training, irrespective of the number of sessions attended; z = -3.656, p training. The TRCs proved acceptable to group members, but should be validated against standard anxiety measures. Further exploration of the application of relaxation techniques in clinical practice is desirable. Implications for Rehabilitation Anxiety is prevalent after stroke and likely affects rehabilitation outcomes. Relaxation training is a well proven treatment for anxiety in the non-stroke population. A significant within session reduction in tension, a hallmark symptom of anxiety, was evidenced via group relaxation training delivered in a post-acute, in-patient stroke unit setting. Relaxation training a shows promise as a treatment for anxiety after stroke.

Multilayer Relaxation and Surface Energies of Metallic Surfaces

Science.gov (United States)

Bozzolo, Guillermo; Rodriguez, Agustin M.; Ferrante, John

1994-01-01

The perpendicular and parallel multilayer relaxations of fcc (210) surfaces are studied using equivalent crystal theory (ECT). A comparison with experimental and theoretical results is made for AI(210). The effect of uncertainties in the input parameters on the magnitudes and ordering of surface relaxations for this semiempirical method is estimated. A new measure of surface roughness is proposed. Predictions for the multilayer relaxations and surface energies of the (210) face of Cu and Ni are also included.

Levitation and guidance force relaxations of the single-seeded and multi-seeded YBCO superconductors

Science.gov (United States)

Abdioglu, M.; Ozturk, K.; Kabaer, M.; Ekici, M.

2018-01-01

The stable levitation and guidance forces at higher force levels are important parameters for technological applicability of high temperature superconductors (HTSs) in Maglev and Flywheel energy storage systems. In this study, we have investigated the levitation and guidance force relaxation of both the single-seeded and multi-seeded YBCOs for different (HTS)-permanent magnetic guideway (PMG) arrangements in different cooling heights (CH). The measured saturated force values of Halbach PMG arrangements are bigger than the maximum force values of other PMGs. It is determined that the normalized magnetic levitation force (MLF) and normalized guidance force (GF) relaxation rate values decrease while the relaxation rates increase with increasing magnetic pole number and the effective external magnetic field area for both the single-seeded and multi-seeded YBCO. Also it can be said that the force stability at the higher force value of Halbach PMG arrangement indicates that the relaxation quality of Halbach PMG is better than that of the others. Additionally, it can be said that both the MLF and GF relaxation qualities of the multi-seeded YBCOs are better than that of the single-seeded ones. This magnetic force and relaxation results of the single-seeded and multi-seeded YBCOs are useful to optimize the loading capacity and lateral reliability of HTS Maglev and similar magnetic bearing systems.

[Electroencephalographic effects of chlorphenesin carbamate, a new central muscle relaxant, in rabbits (author's transl)].

Science.gov (United States)

Watanabe, S; Araki, H; Kawasaki, H; Ueki, S

1977-05-01

Electroencephalographic (EEG) effects of chlorphenesin carbamate were investigated in rabbits with chronic electrode implants, and compared with those of chlormezanone and methocarbamol. Chlorphenesin carbamate (50 mg/kg i.v., 100 mg/kg i.d.) induced a drowsy pattern of spontaneous EEG consisting of high voltage slow waves in the cortex and amygdala, and desynchronization of hippocampal theta waves. Chlormezanone also elicited similar EEG changes but such were much more potent than chlorphenesin carbamate. Methocarbamol showed no effect on spontaneous EEG. Chlorphenesin carbamate caused sedation in this period and muscle relaxation was more potent than that of chlormezanone. The EEG arousal response to auditory stimulation and to electric stimulation of the posterior hypothalamus, centromedian thalamus and mesencephalic reticular formation was slightly depressed by chlorphenesin carbamate. Chlorphenesin carbamate, as with chlormezanone, markedly depressed the limbic afterdischarges elicited by hippocampal stimulation. These EEG effects of chlorphenesin carbamate were qualitatively similar to but much weaker than those of chlormezanone, whereas the muscle relaxant effect of chlorphenesin carbamate was more potent than that of chlormezanone.

Parametric study of the relaxation zone behind strong normal shock waves in a dusty ionized monatomic gas

International Nuclear Information System (INIS)

Igra, O.; Ben-Dor, G.

1982-01-01

The conservation equations appropriate to a steady, one-dimensional flow of dusty ionized argon were solved numerically. The specific effect of each of the physical parameters of the dust upon the flow properties in the relaxation zone is studied. It is found that increasing the dust particle mass causes an increase in both the kinematic and thermal relaxation lengths. In addition to these changes, the flow field inside the relaxation zone is also affected. An increase in the dust mass (caused either by an increase in the dust density or its diameter) causes an increase in the plasma velocity, temperature and electron number density and a decrease in its density and pressure. Similar effects are encountered when the specific heat capacity of the dust is changed. An increase in the emissivity of the dust causes an increase in the plasma density and pressure and a decrease in its velocity, temperature and electron number density. Increasing the emissivity of the dust results in a decrease in the relaxation zone length. (author)

Dynamical relaxation in 2HDM models

Science.gov (United States)

Lalak, Zygmunt; Markiewicz, Adam

2018-03-01

Dynamical relaxation provides an interesting solution to the hierarchy problem in face of the missing signatures of any new physics in recent experiments. Through a dynamical process taking place in the inflationary phase of the Universe it manages to achieve a small electroweak scale without introducing new states observable in current experiments. Appropriate approximation makes it possible to derive an explicit formula for the final vevs in the double-scanning scenario extended to a model with two Higgs doublets (2HDM). Analysis of the relaxation in the 2HDM confirms that in a general case it is impossible to keep vevs of both scalars small, unless fine-tuning is present or additional symmetries are cast upon the Lagrangian. Within the slightly constrained variant of the 2HDM, where odd powers of the fields’ expectation values are not present (which can be easily enforced by requiring that the doublets have different gauge transformations or by imposing a global symmetry) it is shown that the difference between the vevs of two scalars tends to be proportional to the cutoff. The analysis of the relaxation in 2HDM indicates that in a general case the relaxation would be stopped by the first doublet that gains a vev, with the other one remaining vevless with a mass of the order of the cutoff. This happens to conform with the inert doublet model.

Spin relaxation of radicals in cryptochrome and its role in avian magnetoreception

Energy Technology Data Exchange (ETDEWEB)

Worster, Susannah; Kattnig, Daniel R.; Hore, P. J., E-mail: peter.hore@chem.ox.ac.uk [Department of Chemistry, Physical and Theoretical Chemistry Laboratory, University of Oxford, South Parks Road, Oxford OX1 3QZ (United Kingdom)

2016-07-21

Long-lived spin coherence and rotationally ordered radical pairs have previously been identified as key requirements for the radical pair mechanism of the avian magnetic compass sense. Both criteria are hard to meet in a biological environment, where thermal motion of the radicals creates dynamic disorder and drives efficient spin relaxation. This has long been cited as a major stumbling block of the radical pair hypothesis. Here we combine Redfield relaxation theory with analytical solutions to a rotational diffusion equation to assess the impact of restricted rotational motion of the radicals on the operation of the compass. The effects of such motions are first investigated generally in small, model systems and are then critically examined in the magnetically sensitive flavin-tryptophan radical pair that is formed photochemically in the proposed magnetoreceptor protein, cryptochrome. We conclude that relaxation is slowest when rotational motion of the radicals within the protein is fast and highly constrained; that in a regime of slow relaxation, the motional averaging of hyperfine interactions has the potential to improve the sensitivity of the compass; and that consideration of motional effects can significantly alter the design criteria for an optimal compass. In addition, we demonstrate that motion of the flavin radical is likely to be compatible with its role as a component of a functioning radical-pair compass, whereas the motion of the tryptophan radical is less ideal, unless it is particularly fast.

Thermal effect of Zn quantum dots grown on Si(111): competition between relaxation and reconstraint

Science.gov (United States)

Kao, Li-Chi; Huang, Bo-Jia; Zheng, Yu-En; Tu, Kai-Teng; Chiu, Shang-Jui; Ku, Ching-Shun; Lo, Kuang Yao

2018-01-01

Zn dots are potential solutions for metal contacts in future nanodevices. The metastable states that exist at the interface between Zn quantum dots and oxide-free Si(111) surfaces can suppress the development of the complete relaxation and increase the size of Zn dots. In this work, the actual heat consumption of the structural evolution of Zn dots resulting from extrinsic thermal effect was analyzed. Zn dots were coherently grown on oxide-free Si(111) through magnetron RF sputtering. A compensative optical method combined with reflective second harmonic generation and synchrotron x-ray diffraction (XRD) was developed to statistically analyze the thermal effect on the Zn dot system. Pattern matching (3 m) between the Zn and oxide-free Si(111) surface enabled Si(111) to constrain Zn dots from a liquid to solid phase. Annealing under vacuum induced smaller, loose Zn dots to be reconstrained by Si(111). When the size of the Zn dots was in the margin of complete relaxation, the Zn dot was partially constrained by potential barriers (metastable states) between Zn(111) and one of the six in-planes of Si〈110〉. The thermal disturbance exerted by annealing would enable partially constrained ZnO/Zn dots to overcome the potential barrier and be completely relaxed, which is obvious on the transition between Zn(111) and Zn(002) peak in synchrotron XRD. Considering the actual irradiated surface area of dots array in a wide-size distribution, the competition between reconstrained and relaxed Zn dots on Si(111) during annealing was statistically analyzed.

Pre-relaxation in weakly interacting models

Science.gov (United States)

Bertini, Bruno; Fagotti, Maurizio

2015-07-01

We consider time evolution in models close to integrable points with hidden symmetries that generate infinitely many local conservation laws that do not commute with one another. The system is expected to (locally) relax to a thermal ensemble if integrability is broken, or to a so-called generalised Gibbs ensemble if unbroken. In some circumstances expectation values exhibit quasi-stationary behaviour long before their typical relaxation time. For integrability-breaking perturbations, these are also called pre-thermalisation plateaux, and emerge e.g. in the strong coupling limit of the Bose-Hubbard model. As a result of the hidden symmetries, quasi-stationarity appears also in integrable models, for example in the Ising limit of the XXZ model. We investigate a weak coupling limit, identify a time window in which the effects of the perturbations become significant and solve the time evolution through a mean-field mapping. As an explicit example we study the XYZ spin-\\frac{1}{2} chain with additional perturbations that break integrability. One of the most intriguing results of the analysis is the appearance of persistent oscillatory behaviour. To unravel its origin, we study in detail a toy model: the transverse-field Ising chain with an additional nonlocal interaction proportional to the square of the transverse spin per unit length (2013 Phys. Rev. Lett. 111 197203). Despite being nonlocal, this belongs to a class of models that emerge as intermediate steps of the mean-field mapping and shares many dynamical properties with the weakly interacting models under consideration.

Vibrational-rotational relaxation of the simplest hydrogen-containing molecules (review)

International Nuclear Information System (INIS)

Molevich, N.E.; Oraevskii, A.N.

1987-01-01

In connection with the development of chemical lasers much attention is now devoted to the study of kinetic processes is gaseous mixtures containing the hydrogen halides. Vibrational relaxation of molecules if primarily studied without specifying its relation to the rational levels. Rotational relaxation is regarded a priori as faster than vibrational relaxation, so that the population of the rotational levels is assumed to be in equilibrium. This approach to the relaxation of hydrogen halide molecules (and other diatomic hydrogen-containing molecules), however, is unable to explain satisfactorily the results of the papers discussed below. An analysis of the data obtained in these papers leads to the conclusion that the general picture of relaxation in diatomic hydrogen-containing molecules must be viewed as a unified process of vibrational and rotational relaxation. It is shown that those effects observed during vibrational relaxation of such molecules which are unusual from the standpoint of the theory of vibrational-translational relaxation are well explained in terms of intermolecular vibrational-rotational relaxation together with pure rotational relaxation

Pharmacology of Endothelium-Dependent and Independent Relaxation of Rabbit Aorta

DEFF Research Database (Denmark)

Larsen, Kirsten Vendelbo

2001-01-01

The purpose of this study was to investigate several aspects of the acetylcholine-evoked relaxation of blood vessels: methodologic aspects; gender; storage; elevated glucose incubation; the signal transduction pathway; and effects of prolonged exposure. Furthermore, the relaxing effect of some ad...

[Neurogenic communication disorders: how effective are relaxation therapy and acupuncture?].

Science.gov (United States)

Ptok, M

2008-12-01

Not only neurologists but also ENT-physicians and phoniatricians have to prescribe speech and language therapy for patients with communication disorders. Complementary and alternative medicine (CAM) has gained increasing popularity among patients. Many studies have investigated these procedures and positive effects on certain physical e. g., chronic pain and anxiety disorders could be validated. Unfortunately only few empirical investigations have targeted the use of CAM to treat neurogenic disorders of communication or cognition. In this review we provide an overview over general therapeutical principals of two widely used approaches, relaxation therapy and acupuncture. Then we survey the literature and summarize existent research literature regarding the effects of the treatment of neurogenic disorders including dementia.

Effect of interaction range on phonon relaxation in Fermi-Pasta-Ulam beta chain.

Science.gov (United States)

Santhosh, G; Kumar, Deepak

2007-08-01

We study the effect of increasing the range of interactions on phonon relaxation in a chain of atoms with quartic anharmonicity. The study is motivated by recent numerical studies, showing that the value of the exponent alpha characterizing the divergence of conductivity with system size apparently depends on the presence of second neighbor couplings. We perform a quantum calculation of the wave-vector (q) dependent relaxation rate gamma(q) in the second order perturbation theory. The nonanalytic dependence of gamma(q) arises due to small-q singularity of the collision integral. We find that gamma(q) proportional to Aq(5/3) + Bq2. This gives rise to an asymptotic value alpha = 0.4, but the q2 terms lead to a higher apparent value of alpha at small sizes of the chain.

The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

International Nuclear Information System (INIS)

Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G; Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S

2011-01-01

Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

STUDY TO COMPARE THE EFFECTIVENESS OF STATIC STRETCH AND HOLD RELAX TECHNIQUE OVER HAMSTRING FLEXIBILITY

Directory of Open Access Journals (Sweden)

Shanthi C

2014-10-01

Full Text Available Background: Numerous studies have documented on flexibility of muscles. Flexibility is defined as the ability of the muscles to lengthen allowing one joint or more than one joint in a series to move through a range of motion .Flexibility allows tissue to accommodate more easily to stress thus minimizing or preventing muscle injury. But this study sought to identify the study to compare the effectiveness of Static stretch and Hold relax technique over the hamstring flexibility. Methods: 30 healthy male adults with Hamstring tightness aged 21 to 35 years selected from general population through simple randomized technique. Samples are divided into two groups, static stretch Group-I(no.15 and Group-II Hold relax (no.=15.The outcome was measured with help of sit & reach test to see the Hamstring flexibility. Results: Comparison of the post test values of the group I and group II shows a significant difference between the outcomes of two groups with a “t” calculated value of 0.738 (unpaired “t” test. Conclusion: Both static stretch and hold relax Technique can cause very highly significant result in Hamstring Flexibility, further comparison shows very high significant difference between two groups and concludes that hold relax is better than static stretch in Hamstring Flexibility.

The effect of polymer coatings on proton transverse relaxivities of aqueous suspensions of magnetic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Carroll, Matthew R J; House, Michael J; Woodward, Robert C; St Pierre, Timothy G [School of Physics, University of Western Australia, 35 Stirling Hwy, Crawley, WA 6009 (Australia); Huffstetler, Phillip P; Miles, William C; Goff, Jonathon D; Davis, Richey M; Riffle, Judy S, E-mail: stpierre@physics.uwa.edu.au [Macromolecules and Interfaces Institute, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 (United States)

2011-08-12

Iron oxide magnetic nanoparticles are good candidates for magnetic resonance imaging (MRI) contrast agents due to their high magnetic susceptibilities. Here we investigate 19 polyether-coated magnetite nanoparticle systems comprising three series. All systems were synthesized from the same batch of magnetite nanoparticles. A different polyether was used for each series. Each series comprised systems with systematically varied polyether loadings per particle. A highly significant (p < 0.0001) linear correlation (r = 0.956) was found between the proton relaxivity and the intensity-weighted average diameter measured by dynamic light scattering in the 19 particle systems studied. The intensity-weighted average diameter measured by dynamic light scattering is sensitive to small number fractions of larger particles/aggregates. We conclude that the primary effect leading to differences in proton relaxivity between systems arises from the small degree of aggregation within the samples, which appears to be determined by the nature of the polymer and, for one system, the degree of polymer loading of the particles. For the polyether coatings used in this study, any changes in relaxivity from differences in water exclusion or diffusion rates caused by the polymer are minor in comparison with the changes in relaxivity resulting from variations in the degree of aggregation.

Effect of magnetic field on charge imbalance relaxation of non-equilibrium superconductivity

International Nuclear Information System (INIS)

Tsuboi, Kazuki; Yagi, Ryuta

2010-01-01

We have studied relaxation of charge imbalance of non-equilibrium superconductivity in magnetic field. We found that excess current due to charge imbalance showed striking dependence on magnitude of magnetic field and its orientation. We discussed origin of the relaxation.

Effect of Progressive Muscle Relaxation on Social Performance and Quality of Life in Aging

Directory of Open Access Journals (Sweden)

Ali Hassanpour Dehkordi

2016-07-01

Conclusion: The findings of this study revealed that the progressive muscle relaxation technique can effectively reduce the duration of rehabilitation, days of hospitalization and healthcare costs, as well as improve the quality of life, mood, and mental health in the elderly people.

ASM-024, a piperazinium compound, promotes the in vitro relaxation of β2-adrenoreceptor desensitized tracheas.

Science.gov (United States)

Israël-Assayag, Evelyne; Beaulieu, Marie-Josée; Cormier, Yvon

2015-01-01

Inhaled β2-adrenoreceptor agonists are widely used in asthma and chronic obstructive pulmonary disease (COPD) for bronchoconstriction relief. β2-Adrenoreceptor agonists relax airway smooth muscle cells via cyclic adenosine monophosphate (cAMP) mediated pathways. However, prolonged stimulation induces functional desensitization of the β2-adrenoreceptors (β2-AR), potentially leading to reduced clinical efficacy with chronic or prolonged administration. ASM-024, a small synthetic molecule in clinical stage development, has shown activity at the level of nicotinic receptors and possibly at the muscarinic level and presents anti-inflammatory and bronchodilator properties. Aerosolized ASM-024 reduces airway resistance in mice and promotes in-vitro relaxation of tracheal and bronchial preparations from animal and human tissues. ASM-024 increased in vitro relaxation response to maximally effective concentration of short-acting beta-2 agonists in dog and human bronchi. Although the precise mechanisms by which ASM-024 promotes airway smooth muscle (ASM) relaxation remain unclear, we hypothesized that ASM-024 will attenuate and/or abrogate agonist-induced contraction and remain effective despite β2-AR tachyphylaxis. β2-AR tachyphylaxis was induced with salbutamol, salmeterol and formoterol on guinea pig tracheas. The addition of ASM-024 relaxed concentration-dependently intact or β2-AR desensitized tracheal rings precontracted with methacholine. ASM-024 did not induce any elevation of intracellular cAMP in isolated smooth muscle cells; moreover, blockade of the cAMP pathway with an adenylate cyclase inhibitor had no significant effect on ASM-024-induced guinea pig trachea relaxation. Collectively, these findings show that ASM-024 elicits relaxation of β2-AR desensitized tracheal preparations and suggest that ASM-024 mediates smooth muscle relaxation through a different target and signaling pathway than β2-adrenergic receptor agonists. These findings suggest ASM-024

Mechanism of action of relaxant effect of Agastache mexicana ssp.mexicana essential oil in guinea-pig trachea smooth muscle.

Science.gov (United States)

Navarrete, Andrés; Ávila-Rosas, Natalia; Majín-León, Mateo; Balderas-López, José Luis; Alfaro-Romero, Alejandro; Tavares-Carvalho, José Carlos

2017-12-01

Agastache mexicana ssp. mexicana (Kunth) Lint & Epling (Lamiaceae), popularly known as 'toronjil morado', is used in Mexican traditional medicine for the treatment of several diseases such as hypertension, anxiety and respiratory disorders. This study investigates the relaxant action mechanism of A. mexicana ssp. mexicana essential oil (AMEO) in guinea-pig isolated trachea model. AMEO was analyzed by GC/MS. The relaxant effect of AMEO (5-50 μg/mL) was tested in guinea-pig trachea pre-contracted with carbachol (3 × 10  -   6  M) or histamine (3 × 10  -   5  M) in the presence or absence of glibenclamide (10  -   5  M), propranolol (3 × 10  -   6  M) or 2',5'-dideoxyadenosine (10  -   5  M). The antagonist effect of AMEO (10-300 μg/mL) against contractions elicited by carbachol (10  -   15 -10  -   3  M), histamine (10  -   15 -10  -   3  M) or calcium (10-300 μg/mL) was evaluated. Essential oil composition was estragole, d-limonene and linalyl anthranilate. AMEO relaxed the carbachol (EC 50  =   18.25 ± 1.03 μg/mL) and histamine (EC 50  =   13.3 ± 1.02 μg/mL)-induced contractions. The relaxant effect of AMEO was not modified by the presence of propranolol, glibenclamide or 2',5'-dideoxyadenosine, suggesting that effect of AMEO is not related to β 2 -adrenergic receptors, ATP-sensitive potassium channels or adenylate cyclase activation. AMEO was more potent to antagonize histamine (pA 2 ' = -1.507 ± 0.122) than carbachol (pA 2 ' = -2.180 ± 0.357). Also, AMEO antagonized the calcium chloride-induced contractions. The results suggest that relaxant effect of AMEO might be due to blockade of calcium influx in guinea-pig trachea smooth muscle. It is possible that estragole and d-limonene could contribute majority in the relaxant effect of AMEO.

Pharmacological characterization of the relaxant effect induced by adrenomedullin in rat cavernosal smooth muscle

Energy Technology Data Exchange (ETDEWEB)

Leite, L.N. [Programa de Pós-Graduação em Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Laboratório de Farmacologia, Departamento de Enfermagem Psiquiátrica e Ciências Humanas, Escola de Enfermagem de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Gonzaga, N.A. [Programa de Pós-Graduação em Farmacologia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Tirapelli, D.P.C.; Tirapelli, L.F. [Departamento de Cirurgia e Anatomia, Faculdade de Medicina de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil); Tirapelli, C.R. [Laboratório de Farmacologia, Departamento de Enfermagem Psiquiátrica e Ciências Humanas, Escola de Enfermagem de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto, SP (Brazil)

2014-08-15

The aim of the present study was to determine the mechanisms underlying the relaxant effect of adrenomedullin (AM) in rat cavernosal smooth muscle (CSM) and the expression of AM system components in this tissue. Functional assays using standard muscle bath procedures were performed in CSM isolated from male Wistar rats. Protein and mRNA levels of pre-pro-AM, calcitonin receptor-like receptor (CRLR), and Subtypes 1, 2 and 3 of the receptor activity-modifying protein (RAMP) family were assessed by Western immunoblotting and quantitative real-time polymerase chain reaction, respectively. Nitrate and 6-keto-prostaglandin F{sub 1α} (6-keto-PGF{sub 1α}; a stable product of prostacyclin) levels were determined using commercially available kits. Protein and mRNA of AM, CRLR, and RAMP 1, -2, and -3 were detected in rat CSM. Immunohistochemical assays demonstrated that AM and CRLR were expressed in rat CSM. AM relaxed CSM strips in a concentration-dependent manner. AM{sub 22-52}, a selective antagonist for AM receptors, reduced the relaxation induced by AM. Conversely, CGRP{sub 8-37}, a selective antagonist for calcitonin gene-related peptide receptors, did not affect AM-induced relaxation. Preincubation of CSM strips with N{sup G}-nitro-L-arginine-methyl-ester (L-NAME, nitric oxide synthase inhibitor), 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, quanylyl cyclase inhibitor), Rp-8-Br-PET-cGMPS (cGMP-dependent protein kinase inhibitor), SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazole, selective cyclooxygenase-1 inhibitor], and 4-aminopyridine (voltage-dependent K{sup +} channel blocker) reduced AM-induced relaxation. On the other hand, 7-nitroindazole (selective neuronal nitric oxide synthase inhibitor), wortmannin (phosphatidylinositol 3-kinase inhibitor), H89 (protein kinase A inhibitor), SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, adenylate cyclase inhibitor], glibenclamide (selective blocker of ATP-sensitive K{sup +} channels), and

Pharmacological characterization of the relaxant effect induced by adrenomedullin in rat cavernosal smooth muscle

International Nuclear Information System (INIS)

Leite, L.N.; Gonzaga, N.A.; Tirapelli, D.P.C.; Tirapelli, L.F.; Tirapelli, C.R.

2014-01-01

The aim of the present study was to determine the mechanisms underlying the relaxant effect of adrenomedullin (AM) in rat cavernosal smooth muscle (CSM) and the expression of AM system components in this tissue. Functional assays using standard muscle bath procedures were performed in CSM isolated from male Wistar rats. Protein and mRNA levels of pre-pro-AM, calcitonin receptor-like receptor (CRLR), and Subtypes 1, 2 and 3 of the receptor activity-modifying protein (RAMP) family were assessed by Western immunoblotting and quantitative real-time polymerase chain reaction, respectively. Nitrate and 6-keto-prostaglandin F 1α (6-keto-PGF 1α ; a stable product of prostacyclin) levels were determined using commercially available kits. Protein and mRNA of AM, CRLR, and RAMP 1, -2, and -3 were detected in rat CSM. Immunohistochemical assays demonstrated that AM and CRLR were expressed in rat CSM. AM relaxed CSM strips in a concentration-dependent manner. AM 22-52 , a selective antagonist for AM receptors, reduced the relaxation induced by AM. Conversely, CGRP 8-37 , a selective antagonist for calcitonin gene-related peptide receptors, did not affect AM-induced relaxation. Preincubation of CSM strips with N G -nitro-L-arginine-methyl-ester (L-NAME, nitric oxide synthase inhibitor), 1H-(1,2,4)oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, quanylyl cyclase inhibitor), Rp-8-Br-PET-cGMPS (cGMP-dependent protein kinase inhibitor), SC560 [5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-trifluoromethyl pyrazole, selective cyclooxygenase-1 inhibitor], and 4-aminopyridine (voltage-dependent K + channel blocker) reduced AM-induced relaxation. On the other hand, 7-nitroindazole (selective neuronal nitric oxide synthase inhibitor), wortmannin (phosphatidylinositol 3-kinase inhibitor), H89 (protein kinase A inhibitor), SQ22536 [9-(tetrahydro-2-furanyl)-9H-purin-6-amine, adenylate cyclase inhibitor], glibenclamide (selective blocker of ATP-sensitive K + channels), and apamin (Ca 2+ -activated

Effects of Ginger and Its Constituents on Airway Smooth Muscle Relaxation and Calcium Regulation

Science.gov (United States)

Siviski, Matthew E.; Zhang, Yi; Xu, Carrie; Hoonjan, Bhupinder; Emala, Charles W.

2013-01-01

The prevalence of asthma has increased in recent years, and is characterized by airway hyperresponsiveness and inflammation. Many patients report using alternative therapies to self-treat asthma symptoms as adjuncts to short-acting and long-acting β-agonists and inhaled corticosteroids (ICS). As many as 40% of patients with asthma use herbal therapies to manage asthma symptoms, often without proven efficacy or known mechanisms of action. Therefore, investigations of both the therapeutic and possible detrimental effects of isolated components of herbal treatments on the airway are important. We hypothesized that ginger and its active components induce bronchodilation by modulating intracellular calcium ([Ca2+]i) in airway smooth muscle (ASM). In isolated human ASM, ginger caused significant and rapid relaxation. Four purified constituents of ginger were subsequently tested for ASM relaxant properties in both guinea pig and human tracheas: [6]-gingerol, [8]-gingerol, and [6]-shogaol induced rapid relaxation of precontracted ASM (100–300 μM), whereas [10]-gingerol failed to induce relaxation. In human ASM cells, exposure to [6]-gingerol, [8]-gingerol, and [6]-shogaol, but not [10]-gingerol (100 μM), blunted subsequent Ca2+ responses to bradykinin (10 μM) and S-(−)-Bay K 8644 (10 μM). In A/J mice, the nebulization of [8]-gingerol (100 μM), 15 minutes before methacholine challenge, significantly attenuated airway resistance, compared with vehicle. Taken together, these novel data show that ginger and its isolated active components, [6]-gingerol, [8]-gingerol, and [6]-shogaol, relax ASM, and [8]-gingerol attenuates airway hyperresponsiveness, in part by altering [Ca2+]i regulation. These purified compounds may provide a therapeutic option alone or in combination with accepted therapeutics, including β2-agonists, in airway diseases such as asthma. PMID:23065130

Electron spin relaxation in cryptochrome-based magnetoreception

DEFF Research Database (Denmark)

Kattnig, Daniel R; Solov'yov, Ilia A; Hore, P J

2016-01-01

The magnetic compass sense of migratory birds is thought to rely on magnetically sensitive radical pairs formed photochemically in cryptochrome proteins in the retina. An important requirement of this hypothesis is that electron spin relaxation is slow enough for the Earth's magnetic field to have...... this question for a structurally characterized model cryptochrome expected to share many properties with the putative avian receptor protein. To this end we combine all-atom molecular dynamics simulations, Bloch-Redfield relaxation theory and spin dynamics calculations to assess the effects of spin relaxation...... on the performance of the protein as a compass sensor. Both flavin-tryptophan and flavin-Z˙ radical pairs are studied (Z˙ is a radical with no hyperfine interactions). Relaxation is considered to arise from modulation of hyperfine interactions by librational motions of the radicals and fluctuations in certain...

The effect of relaxation techniques on edema, anxiety and depression in post-mastectomy lymphedema patients undergoing comprehensive decongestive therapy: A clinical trial.

Science.gov (United States)

Abbasi, Bahareh; Mirzakhany, Navid; Angooti Oshnari, Leila; Irani, Ashkan; Hosseinzadeh, Samaneh; Tabatabaei, Seyed Mehdi; Haghighat, Shahpar

2018-01-01

Lymphedema is sometimes accompanied by high degrees of anxiety and depression. This study aimed to assess the effects of relaxation techniques on the level of edema, anxiety and depression in women undergoing Comprehensive Decongestive Therapy (CDT). This clinical trial compared two treatment methods in 31 women with post-mastectomy lymphedema, including 15 cases who received CDT and 16 who received RCDT (Relaxation plus CDT). The edema volume, anxiety and depression scores were compared at the first and last sessions of the first phase of the treatment and six weeks afterwards. The edema, anxiety and depression scores were 63.6%, 54.1% and 65.5% in the RCDT group and 60.7%, 31.4% and 35.2% in the CDT group. There were significant differences between the two groups in terms of the reduction in depression (p = 0.024) and anxiety (p = 0.011) scores throughout the study. This significant relationship was due to the differences in the depression score in the 3rd and 9th weeks of the study between the two groups. Similarly, anxiety levels differed significantly between the two groups at the 9th week of the study (P = 0.013). Relaxation techniques reduced the anxiety and depression scores and the volume of edema in the patients with lymphedema. The addition of this intervention to the therapeutic package for lymphedema patients requires further studies in terms of cost-effectiveness.

Tensile, creep and relaxation characteristics of zircaloy cladding at 3850C

International Nuclear Information System (INIS)

Murty, K.L.; McDonald, S.G.

1981-01-01

Axial creep tests were carried out at stresses ranging form 30 ksi to 50 ksi. Steady-state creep rates were evaluated from stress change tests to minimize the number of samples. The secondary creep rate was related to the applied stress through a Sinh function. The functional dependence of the strain rate on the stress was also evaluated from load relaxation tests. It is demonstrated that the strain rates derived from load relaxation tests are identical to the creep data when the relaxation testing was carried out at the point of maximum load in a tensile test. In addition, the creep and relaxation results are identical to the true ultimate tensile stress versus applied strain-rate data derived from tensile tests. (orig./HP)

The Effect of Progressive Muscle Relaxation on The Occupational Stress of Nurses in Critical Care Units

Directory of Open Access Journals (Sweden)

Pegah Matourypour

2012-10-01

Full Text Available Background and objective: In the nursing profession, there are numerous factors which altogether cause occupational stress and as a result occupational exhaustion in nurses and decrease the quality of patient care. Regarding the importance of this issue which influences the health indices of the society, this study investigates the effect of progressive muscle relaxation on the occupational stress of nurses.Materials and Methods: This semi-experimental and before-after study was conducted using progressive muscle relaxation intervention on 33 nurses in special treatment (ICU and CCU and emergency units through simple sampling in Yazd in 2012. To assess occupational stress,Toft-Anderson questionnaire was used. The procedure of applying relaxation in a practical way was given to nurses in pamphlets and questionnaires were filled before and two weeks after the intervention. Analysis was done using SPSS.16 software and T-test.Results: The average total score of stress in nurses before and after the intervention was determined as – 28.12±43.74 and 52.12±04.72 respectively and this difference was not statistically significant (39.0>p. However, in the dimensions of nurses’ workload (/0>p 03 and t=2.27 and patients’ suffering and death, these scores were significantly different (0001.0>p and t=3.94.Conclusion: This study showed that applying progressive muscle relaxation technique as a method of emotion-focused coping cannot be effective in the reduction of occupational stress in nurses.

The effect of progressive muscle relaxation techniques on anxiety in Patients with myocardial infarction

Directory of Open Access Journals (Sweden)

Mozhgan Jariani

2011-12-01

Conclusion: progressive muscle relaxation can reduce the amount of anxiety, and systolic and diastolic blood pressure of the patients with myocardial infarction hospitalized in CCU ward, therefore it can play an effective role as a supplement non-medicinal, simple and cheap treatment for these patients

Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: longitudinal relaxation dispersion for spin I = 1.

Science.gov (United States)

Nilsson, Tomas; Halle, Bertil

2012-08-07

The frequency dependence of the longitudinal relaxation rate, known as the magnetic relaxation dispersion (MRD), can provide a frequency-resolved characterization of molecular motions in complex biological and colloidal systems on time scales ranging from 1 ns to 100 μs. The conformational dynamics of immobilized proteins and other biopolymers can thus be probed in vitro or in vivo by exploiting internal water molecules or labile hydrogens that exchange with a dominant bulk water pool. Numerous water (1)H and (2)H MRD studies of such systems have been reported, but the widely different theoretical models currently used to analyze the MRD data have resulted in divergent views of the underlying molecular motions. We have argued that the essential mechanism responsible for the main dispersion is the exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings when internal water molecules or labile hydrogens escape from orientationally confining macromolecular sites. In the EMOR model, the exchange process is thus not just a means of mixing spin populations but it is also the direct cause of spin relaxation. Although the EMOR theory has been used in several studies to analyze water (2)H MRD data from immobilized biopolymers, the fully developed theory has not been described. Here, we present a comprehensive account of a generalized version of the EMOR theory for spin I = 1 nuclides like (2)H. As compared to a previously described version of the EMOR theory, the present version incorporates three generalizations that are all essential in applications to experimental data: (i) a biaxial (residual) electric field gradient tensor, (ii) direct and indirect effects of internal motions, and (iii) multiple sites with different exchange rates. In addition, we describe and assess different approximations to the exact EMOR theory that are useful in various regimes. In particular, we consider the experimentally

Group hypnotherapy versus group relaxation for smoking cessation: an RCT study protocol.

Science.gov (United States)

Dickson-Spillmann, Maria; Kraemer, Thomas; Rust, Kristina; Schaub, Michael

2012-04-04

A significant number of smokers would like to stop smoking. Despite the demonstrated efficacy of pharmacological smoking cessation treatments, many smokers are unwilling to use them; however, they are inclined to try alternative methods. Hypnosis has a long-standing reputation in smoking cessation therapy, but its efficacy has not been scientifically proven. We designed this randomised controlled trial to evaluate the effects of group hypnosis as a method for smoking cessation, and we will compare the results of group hypnosis with group relaxation. This is a randomised controlled trial (RCT) to compare the efficacy of a single session of hypnosis with that of relaxation performed in groups of 8-15 smokers. We intend to include at least 220 participants in our trial. The inclusion criteria include smoking at least 5 cigarettes per day, not using other cessation methods and being willing to quit smoking. The intervention is performed by a trained hypnotist/relaxation therapist. Both groups first receive 40 min of mental preparation that is based on motivational interviewing. Then, a state of deep relaxation is induced in the hypnosis condition, and superficial relaxation is induced in the control condition. Suggestions are made in the hypnosis condition that aim to switch the mental self-image of the participants from that of smokers to that of non-smokers. Each intervention lasts for 40 min. The participants also complete questionnaires that assess their smoking status and symptoms of depression and anxiety at baseline, 2 weeks and 6 months post-intervention. In addition, saliva samples are collected to assess cotinine levels at baseline and at 6 months post-intervention. We also assess nicotine withdrawal symptoms at 2 weeks post-intervention. To the best of our knowledge, this RCT is the first to test the efficacy of group hypnosis versus group relaxation. Issues requiring discussion in the outcome paper include the lack of standardisation of hypnotic

TURBULENCE DECAY AND CLOUD CORE RELAXATION IN MOLECULAR CLOUDS

International Nuclear Information System (INIS)

Gao, Yang; Law, Chung K.; Xu, Haitao

2015-01-01

The turbulent motion within molecular clouds is a key factor controlling star formation. Turbulence supports molecular cloud cores from evolving to gravitational collapse and hence sets a lower bound on the size of molecular cloud cores in which star formation can occur. On the other hand, without a continuous external energy source maintaining the turbulence, such as in molecular clouds, the turbulence decays with an energy dissipation time comparable to the dynamic timescale of clouds, which could change the size limits obtained from Jean's criterion by assuming constant turbulence intensities. Here we adopt scaling relations of physical variables in decaying turbulence to analyze its specific effects on the formation of stars. We find that the decay of turbulence provides an additional approach for Jeans' criterion to be achieved, after which gravitational infall governs the motion of the cloud core. This epoch of turbulence decay is defined as cloud core relaxation. The existence of cloud core relaxation provides a more complete understanding of the effect of the competition between turbulence and gravity on the dynamics of molecular cloud cores and star formation

Adaptive under relaxation factor of MATRA code for the efficient whole core analysis

International Nuclear Information System (INIS)

Kwon, Hyuk; Kim, S. J.; Seo, K. W.; Hwang, D. H.

2013-01-01

Such nonlinearities are handled in MATRA code using outer iteration with Picard scheme. The Picard scheme involves successive updating of the coefficient matrix based on the previously calculated values. The scheme is a simple and effective method for the nonlinear problem but the effectiveness greatly depends on the under-relaxing capability. Accuracy and speed of calculation are very sensitively dependent on the under-relaxation factor in outer-iteration updating the axial mass flow using the continuity equation. The under-relaxation factor in MATRA is generally utilized with a fixed value that is empirically determined. Adapting the under-relaxation factor to the outer iteration is expected to improve the calculation effectiveness of MATRA code rather than calculation with the fixed under-relaxation factor. The present study describes the implementation of adaptive under-relaxation within the subchannel code MATRA. Picard iterations with adaptive under-relaxation can accelerate the convergence for mass conservation in subchannel code MATRA. The most efficient approach for adaptive under relaxation appears to be very problem dependent

The effects of massage and music on pain, anxiety and relaxation in burn patients: Randomized controlled clinical trial.

Science.gov (United States)

Najafi Ghezeljeh, T; Mohades Ardebili, F; Rafii, F

2017-08-01

The aim of this study was to evaluate the effects of massage and music on pain intensity, anxiety intensity and relaxation level in burn patients. Pain and anxiety are common among burn patients, but there are many physical and psychological consequences. This randomized controlled clinical trial with factorial design 2×2 included 240 burn patients admitted at Shahid Motahari Burns Hospital, Tehran, Iran, between September 2013 and May 2015. The patients were allocated into the following groups: (i) control (n=60) receiving the conventional primary care, (ii) music group (n=60) receiving their favorite songs, (iii) massage group (n=60) receiving Swedish massage, and (iv) music-plus-massage group (n=60) receiving a combination of their favorite songs and Swedish massage, for 20min once a day for 3 consecutive days, using random permuted blocks of sizes 4 with a 1:1 ratio. To collect the data before and after the intervention, a specific Visual Analogue Scale (VAS) was applied for pain intensity, anxiety intensity, and relaxation level. The data were analyzed using SPSS, version 21. Our findings showed a decrease in pain and anxiety intensity and an increase in relaxation level in all three intervention groups as compared to the control group, indicating there was no significant difference among the interventions applied. Furthermore, following application of each intervention, pain and anxiety intensity decreased and relaxation level increased in the intervention groups as compared to before intervention. Our results revealed that music, massage and a combination of both interventions were effective on reducing pain and anxiety intensity and increasing relaxation level. Due to easy, low-cost and availability of the interventions applied, these complementary therapies are suggested for the burn patients. Although application of a single complementary therapy is cost-effective, further studies are required to determine the most effective and cost-effective method to

The relaxant effect induced by Allium sativum L. bulb aqueous extract on rat isolated trachea

Science.gov (United States)

Fehri, Badreddine; Ahmed, Mueen K.K.; Aiache, Jean-Marc

2011-01-01

Background: Garlic plays an important role in complementary and alternative medicine. Most people believe in and use herbal products even when they have not been as thoroughly researched as garlic. Garlic is also known for its beneficial effects on the cardiovascular system. Materials and Methods: The relaxant effect of Allium sativum L. bulb aqueous extract (ASBAE) containing 0.06%-0.10% of allicin was studied on isolated smooth muscle of trachea of rats precontracted using acetylcholine (10−5 M). Results: It was found that ASBAE induced a dose-dependent relaxation with recorded EC 50 values of 71.87 ± 5.90 µg/mL (n = 7). Pretreatments with mepyramine (10−7 M), methysergide (10−7 M), caffeine (10−6 M), theophylline (10−6 M), nifedipine (10−6 M), and dipyridamole (10−6 M) did not alter ASBAE concentration-response curves. In turn, concentration-response curves to ASBAE were significantly shifted toward right in the presence of aspirin (3.10−3 M), indomethacin (10−6 M), prazosin (10−6 M), and propranolol (10−7 M). Conclusion: It is suggested that the recorded relaxation results are due to the release of prostaglandins E 1 and E 2 consecutively to α- and β-adrenoreceptor stimulation. PMID:21472073

Breathing and Relaxation

Science.gov (United States)

... Find a Doctor Relaxation is the absence of tension in muscle groups and a minimum or absence ... Drill Meditation Progressive Muscle Relaxation Minimizing Shortness of Breath Visualization This information has been approved by Shelby ...

Effect of water-methanol mixed solvents on the ultrasonic relaxation of cadmium acetate

International Nuclear Information System (INIS)

Sree Rama Murthy, J.; Ramachandra Rao, B.

1976-01-01

Measurements of ultrasonic absorption have been made by pulse technique in 1 M solutions of cadmium acetate with water-methanol mixed solvents. Results are analysed by assuming a single relaxation mechanism. The characteristic frequency of relaxation is found to decrease with increasing composition of methanol in the solvent. It is proposed that the mechanism of relaxation may be perturbation of chemical equilibrium between complex CdAc + ions and Cd ++ , Ac - species by soundwaves. (author)

5 Things To Know About Relaxation Techniques for Stress

Science.gov (United States)

... Techniques for Stress Share: When you’re under stress, your body reacts by releasing hormones that produce the “fight- ... relaxation techniques could counteract the negative effects of stress. ... the body's natural relaxation response, characterized by slower breathing, lower ...

Studying the effect of stress relaxation and creep on lattice strain evolution of stainless steel under tension

International Nuclear Information System (INIS)

Wang, H.; Clausen, B.; Tomé, C.N.; Wu, P.D.

2013-01-01

Due to relatively long associated count times, in situ strain measurements using neutron diffraction requires periodic interruption of the test to collect the diffraction data by holding either the stress or the strain constant. As a consequence, stress relaxation or strain creep induced by the interrupts is inevitable, especially at loads which are close to the flow stress of the material. An in situ neutron diffraction technique, which consists in performing the diffraction measurements using continuous event-mode data collection while conducting the mechanical loading monotonically with a very slow loading rate, is proposed here to avoid the effects associated with interrupts. The lattice strains in stainless steel under uniaxial tension are measured using the three techniques, and the experimental results are compared to study the effect of stress relaxation and strain creep on the lattice strain measurements. The experimental results are simulated using both the elastic viscoplastic self-consistent (EVPSC) model and the elastic plastic self-consistent (EPSC) model. Both the EVPSC and EPSC models give reasonable predictions for all the three tests, with EVPSC having the added advantage over EPSC that it allows us to address the relaxation and creep effects in the interrupted tests

Universal binding energy relation for cleaved and structurally relaxed surfaces

International Nuclear Information System (INIS)

Srirangarajan, Aarti; Datta, Aditi; Gandi, Appala Naidu; Ramamurty, U; Waghmare, U V

2014-01-01

The universal binding energy relation (UBER), derived earlier to describe the cohesion between two rigid atomic planes, does not accurately capture the cohesive properties when the cleaved surfaces are allowed to relax. We suggest a modified functional form of UBER that is analytical and at the same time accurately models the properties of surfaces relaxed during cleavage. We demonstrate the generality as well as the validity of this modified UBER through first-principles density functional theory calculations of cleavage in a number of crystal systems. Our results show that the total energies of all the relaxed surfaces lie on a single (universal) energy surface, that is given by the proposed functional form which contains an additional length-scale associated with structural relaxation. This functional form could be used in modelling the cohesive zones in crack growth simulation studies. We find that the cohesive law (stress–displacement relation) differs significantly in the case where cracked surfaces are allowed to relax, with lower peak stresses occurring at higher displacements. (paper)

Sleep, Stress & Relaxation: Rejuvenate Body & Mind

Science.gov (United States)

Sleep, Stress & Relaxation: Rejuvenate Body & Mind; Relieve Stress; best ways to relieve stress; best way to relieve stress; different ways to relieve stress; does smoking relieve stress; does tobacco relieve stress; how can I relieve stress; how can you relieve stress; how do I relieve stress; reduce stress; does smoking reduce stress; how can I reduce stress; how to reduce stress; reduce stress; reduce stress levels; reducing stress; smoking reduce stress; smoking reduces stress; stress reducing techniques; techniques to reduce stress; stress relief; best stress relief; natural stress relief; need stress relief; relief for stress; relief from stress; relief of stress; smoking and stress relief; smoking for stress relief; smoking stress relief; deal with stress; dealing with stress; dealing with anger; dealing with stress; different ways of dealing with stress; help dealing with stress; how to deal with anger; how to deal with stress; how to deal with stress when quitting smoking; stress management; free stress management; how can you manage stress; how do you manage stress; how to manage stress; manage stress; management of stress; management stress; managing stress; strategies for managing stress; coping with stress; cope with stress; copeing with stress; coping and stress; coping skills for stress; coping strategies for stress; coping strategies with stress; coping strategy for stress; coping with stress; coping with stress and anxiety; emotional health; emotional health; emotional health article; emotional health articles; deep relaxation; deep breathing relaxation techniques; deep muscle relaxation; deep relaxation; deep relaxation meditation; deep relaxation technique; deep relaxation techniques; meditation exercises; mindful exercises; mindful meditation exercises; online relaxation exercises; relaxation breathing exercises; relaxation exercise; relaxation exercises; stress relaxation; methods of relaxation for stress; relax stress; relax techniques stress

Peeling mode relaxation ELM model

International Nuclear Information System (INIS)

Gimblett, C. G.

2006-01-01

This paper discusses an approach to modelling Edge Localised Modes (ELMs) in which toroidal peeling modes are envisaged to initiate a constrained relaxation of the tokamak outer region plasma. Relaxation produces both a flattened edge current profile (which tends to further destabilise a peeling mode), and a plasma-vacuum negative current sheet which has a counteracting stabilising influence; the balance that is struck between these two effects determines the radial extent (rE) of the ELM relaxed region. The model is sensitive to the precise position of the mode rational surfaces to the plasma surface and hence there is a 'deterministic scatter' in the results that has an accord with experimental data. The toroidal peeling stability criterion involves the edge pressure, and using this in conjunction with predictions of rE allows us to evaluate the ELM energy losses and compare with experiment. Predictions of trends with the edge safety factor and collisionality are also made

Effects of Progressive Muscle Relaxation Counseling on Anxiety among Primigravida Women Referred to Health Care Centers in Hamadan

Directory of Open Access Journals (Sweden)

Fateme Shobeiri

2015-09-01

Full Text Available Background and Objectives: Progressive muscle relaxation is a non-invasive, cost-effective and complication less method which can be performed independently by the individual. Considering the importance of psychological problems during pregnancy, the purpose of this study was to evaluate the effect of progressive muscle relaxation counseling on anxiety among primigravida women referred to health care centers in Hamadan, Iran. Materials and Methods: This study was a randomized clinical trial with two groups (experimental and control with pre-test and post-test. A total of 120 women were referred to health centers in Hamadan who were experiencing their first pregnancy and were consecutively enrolled in the study, after obtaining informed consents. They were randomly assigned to intervention and control groups (60 women in each group by allocation concealment. The control group only received routine prenatal care, but the experimental group after two counseling sessions and learning muscle relaxation techniques performed progressive muscle relaxation exercises from 21-22 weeks for 10 weeks, and completed the daily performance sheet of relaxation. The study data collection tools included a demographic questionnaire, Spielberger state-trait anxiety inventory, and the daily performance sheet for the intervention group. Data were analyzed in SPSS 20 using independent samples t-test, Analysis of covariance (ANCOVA, and paired t-test. Results: Data analysis reflected the homogeneity of the state and trait anxiety levels in both groups before the intervention. The results showed that state and trait anxiety in the control group after the intervention was significantly increased (P<0.001, but the experimental group showed a significant decrease in state and trait anxiety after the intervention (P<0.001. Conclusions: Teaching progressive muscle relaxation techniques to pregnant women can have a significant impact on reducing pregnancy anxiety.

Accurate determination of rates from non-uniformly sampled relaxation data

Energy Technology Data Exchange (ETDEWEB)

Stetz, Matthew A.; Wand, A. Joshua, E-mail: wand@upenn.edu [University of Pennsylvania Perelman School of Medicine, Johnson Research Foundation and Department of Biochemistry and Biophysics (United States)

2016-08-15

The application of non-uniform sampling (NUS) to relaxation experiments traditionally used to characterize the fast internal motion of proteins is quantitatively examined. Experimentally acquired Poisson-gap sampled data reconstructed with iterative soft thresholding are compared to regular sequentially sampled (RSS) data. Using ubiquitin as a model system, it is shown that 25 % sampling is sufficient for the determination of quantitatively accurate relaxation rates. When the sampling density is fixed at 25 %, the accuracy of rates is shown to increase sharply with the total number of sampled points until eventually converging near the inherent reproducibility of the experiment. Perhaps contrary to some expectations, it is found that accurate peak height reconstruction is not required for the determination of accurate rates. Instead, inaccuracies in rates arise from inconsistencies in reconstruction across the relaxation series that primarily manifest as a non-linearity in the recovered peak height. This indicates that the performance of an NUS relaxation experiment cannot be predicted from comparison of peak heights using a single RSS reference spectrum. The generality of these findings was assessed using three alternative reconstruction algorithms, eight different relaxation measurements, and three additional proteins that exhibit varying degrees of spectral complexity. From these data, it is revealed that non-linearity in peak height reconstruction across the relaxation series is strongly correlated with errors in NUS-derived relaxation rates. Importantly, it is shown that this correlation can be exploited to reliably predict the performance of an NUS-relaxation experiment by using three or more RSS reference planes from the relaxation series. The RSS reference time points can also serve to provide estimates of the uncertainty of the sampled intensity, which for a typical relaxation times series incurs no penalty in total acquisition time.

An evaluation of the use of modulated temperature DSC as a means of assessing the relaxation behaviour of amorphous lactose.

Science.gov (United States)

Craig, D Q; Barsnes, M; Royall, P G; Kett, V L

2000-06-01

To evaluate the use of Modulated Temperature DSC (MTDSC) as a means of assessing the relaxation behaviour of amorphous lactose via measurement of the heat capacity, glass transition (Tg) and relaxation endotherm. Samples of amorphous lactose were prepared by freeze drying. MTDSC was conducted using a TA Instruments 2920 MDSC using a heating rate of 2 degrees C/minute, a modulation amplitude of +/-0.3 degrees C and a period of 60 seconds. Samples were cycled by heating to 140 degrees C and cooling to a range of annealing temperatures between 80 degrees C and 100 degrees C, followed by reheating through the Tg region. Systems were then recooled to allow for correction of the Tg shift effect. MTDSC enabled separation of the glass transition from the relaxation endotherm, thereby facilitating calculation of the relaxation time as a function of temperature. The relative merits of using MTDSC for the assessment of relaxation processes are discussed. In addition, the use of the fictive temperature rather than the experimentally derived Tg is outlined. MTDSC allows assessment of the glass transition temperature, the magnitude of the relaxation endotherm and the value of the heat capacity, thus facilitating calculation of relaxation times. Limitations identified with the approach include the slow scanning speed, the need for careful choice of experimental parameters and the Tg shift effect.

Effect of psychological intervention in the form of relaxation and guided imagery on cellular immune function in normal healthy subjects. An overview

DEFF Research Database (Denmark)

Zachariae, R; Kristensen, J S; Hokland, P

1991-01-01

The present study measured the effects of relaxation and guided imagery on cellular immune function. During a period of 10 days 10 healthy subjects were given one 1-hour relaxation procedure and one combined relaxation and guided imagery procedure, instructing the subjects to imagine their immune...... on the immune defense and could form the basis of further studies on psychological intervention and immunological status. Udgivelsesdato: 1990-null...

Effects of superparamagnetic iron oxide nanoparticles on the longitudinal and transverse relaxation of hyperpolarized xenon gas

Science.gov (United States)

Burant, Alex; Antonacci, Michael; McCallister, Drew; Zhang, Le; Branca, Rosa Tamara

2018-06-01

SuperParamagnetic Iron Oxide Nanoparticles (SPIONs) are often used in magnetic resonance imaging experiments to enhance Magnetic Resonance (MR) sensitivity and specificity. While the effect of SPIONs on the longitudinal and transverse relaxation time of 1H spins has been well characterized, their effect on highly diffusive spins, like those of hyperpolarized gases, has not. For spins diffusing in linear magnetic field gradients, the behavior of the magnetization is characterized by the relative size of three length scales: the diffusion length, the structural length, and the dephasing length. However, for spins diffusing in non-linear gradients, such as those generated by iron oxide nanoparticles, that is no longer the case, particularly if the diffusing spins experience the non-linearity of the gradient. To this end, 3D Monte Carlo simulations are used to simulate the signal decay and the resulting image contrast of hyperpolarized xenon gas near SPIONs. These simulations reveal that signal loss near SPIONs is dominated by transverse relaxation, with little contribution from T1 relaxation, while simulated image contrast and experiments show that diffusion provides no appreciable sensitivity enhancement to SPIONs.

Functional behavior of the anomalous magnetic relaxation observed in melt-textured YBa_2Cu_3O_7_-_δ samples showing the paramagnetic Meissner effect

International Nuclear Information System (INIS)

Dias, F.T.; Vieira, V.N.; Garcia, E.L.; Wolff-Fabris, F.; Kampert, E.; Gouvêa, C.P.; Schaf, J.; Obradors, X.; Puig, T.; Roa, J.J.

2016-01-01

Highlights: • Paramagnetic Meissner effect observed up to 5T in FCC and FCW measurements. • Time effects evidenced by irreversibilities between FCC and FCW measurements. • Strong time effects causing an anomalous paramagnetic relaxation. • Paramagnetic relaxation governed by different flux dynamics in different intervals. • An interpretative analysis to identify the flux dynamics in the relaxation process. - Abstract: We have studied the functional behavior of the field-cooled (FC) magnetic relaxation observed in melt-textured YBa_2Cu_3O_7_-_δ (Y123) samples with 30 wt% of Y_2Ba_1Cu_1O_5 (Y211) phase, in order to investigate anomalous paramagnetic moments observed during the experiments. FC magnetic relaxation experiments were performed under controlled conditions, such as cooling rate and temperature. Magnetic fields up to 5T were applied parallel to the ab plane and along the c-axis. Our results are associated with the paramagnetic Meissner effect (PME), characterized by positive moments during FC experiments, and related to the magnetic flux compression into the samples. After different attempts our experimental data could be adequately fitted by an exponential decay function with different relaxation times. We discuss our results suggesting the existence of different and preferential flux dynamics governing the anomalous FC paramagnetic relaxation in different time intervals. This work is one of the first attempts to interpret this controversial effect in a simple analysis of the pinning mechanisms and flux dynamics acting during the time evolution of the magnetic moment. However, the results may be useful to develop models to explain this interesting and still misunderstood feature of the paramagnetic Meissner effect.

Tension and relaxation in the individual.

Science.gov (United States)

Newbury, C R

1979-06-01

Increasing materialism in society is resulting in more wide spread nervous tension in all age groups. While some degree of nervous tension is necessary in everyday living, its adverse effects require that we must learn to bring it under control. Total tension is shown to have two components: a controllable element arising from factors in the environment and the inbuilt uncontrollable residue which is basic in the individual temperament. The effects of excessive or uncontrolled stress can be classified as 1) emotional reactions such as neurotic behaviour (anxiety hypochondria, hysteria, phobia, depression obsessions and compulsions) or psychotic behaviour and 2) psychosomatic reactions (nervous asthma, headache, insomnia, heart attack). Nervous energy can be wastefully expended by such factors as loss of temper, wrong attitudes to work, job frustration and marital strains. Relaxation is the only positive way to control undesirable nervous tension and its techniques require to be learned. A number of techniques (progressive relaxation, differential relaxation, hypnosis, the use of biofeedback, Yoga and Transcendental Meditation) are described and their application to dental practice is discussed.

Impacts of Base-Case and Post-Contingency Constraint Relaxations on Static and Dynamic Operational Security

Science.gov (United States)

Salloum, Ahmed

Constraint relaxation by definition means that certain security, operational, or financial constraints are allowed to be violated in the energy market model for a predetermined penalty price. System operators utilize this mechanism in an effort to impose a price-cap on shadow prices throughout the market. In addition, constraint relaxations can serve as corrective approximations that help in reducing the occurrence of infeasible or extreme solutions in the day-ahead markets. This work aims to capture the impact constraint relaxations have on system operational security. Moreover, this analysis also provides a better understanding of the correlation between DC market models and AC real-time systems and analyzes how relaxations in market models propagate to real-time systems. This information can be used not only to assess the criticality of constraint relaxations, but also as a basis for determining penalty prices more accurately. Constraint relaxations practice was replicated in this work using a test case and a real-life large-scale system, while capturing both energy market aspects and AC real-time system performance. System performance investigation included static and dynamic security analysis for base-case and post-contingency operating conditions. PJM peak hour loads were dynamically modeled in order to capture delayed voltage recovery and sustained depressed voltage profiles as a result of reactive power deficiency caused by constraint relaxations. Moreover, impacts of constraint relaxations on operational system security were investigated when risk based penalty prices are used. Transmission lines in the PJM system were categorized according to their risk index and each category was as-signed a different penalty price accordingly in order to avoid real-time overloads on high risk lines. This work also extends the investigation of constraint relaxations to post-contingency relaxations, where emergency limits are allowed to be relaxed in energy market models

[A study on Korean concepts of relaxation].

Science.gov (United States)

Park, J S

1992-01-01

Relaxation technique is an independent nursing intervention used in various stressful situations. The concept of relaxation must be explored for the meaning given by the people in their traditional thought and philosophy. Korean relaxation technique, wanting to become culturally acceptable and effective, is learning to recognize and develop Korean concepts, experiences, and musics of relaxation. This study was aimed at discovering Korean concepts, experiences and musics of relaxation and contributing the development of the relaxation technique for Korean people. The subjects were 59 nursing students, 39 hospitalized patients, 61 housewives, 21 rural residents and 16 researchers. Data were collected from September 4th to October 24th, 1991 by interviews or questionnaires. The data analysis was done by qualitative research method, and validity assured by conformation of the concept and category by 2 nursing scientists who had written a Master's thesis on the relaxation technique. The results of the study were summarized as follows; 1. The meaning of the relaxation concept; From 298 statements, 107 concepts were extracted and then 5 categories "Physical domain", "Psychological domain", "Complex domain", "Situation", and "environment" were organized. 'Don't have discomforts, 'don't have muscle tension', 'don't have energy (him in Korean)', 'don't have activities' subcategories were included in "Physical domain". 'Don't have anxiety', 'feel good', 'emotional stability', 'don't have wordly thoughts', 'feel one's brain muddled', 'loss of desire' subcategories were included in "physical domain" 'Comfort body and mind', 'don't have tension of body and mind', 'be sagged' 'liveliness of thoughts' subcategories were included in "Complex domain". 'Rest', 'sleep', 'others' subcategories were included in "Situation domain". And 'quite environment' & 'comfortable environment' subcategories were included in "Environmental domain". 2. The experiences of the relaxation; From 151

Slowing hot-carrier relaxation in graphene using a magnetic field

Science.gov (United States)

Plochocka, P.; Kossacki, P.; Golnik, A.; Kazimierczuk, T.; Berger, C.; de Heer, W. A.; Potemski, M.

2009-12-01

A degenerate pump-probe technique is used to investigate the nonequilibrium carrier dynamics in multilayer graphene. Two distinctly different dynamics of the carrier relaxation are observed. A fast relaxation (˜50fs) of the carriers after the initial effect of phase-space filling followed by a slower relaxation (˜4ps) due to thermalization. Both relaxation processes are less efficient when a magnetic field is applied at low temperatures which is attributed to the suppression of the electron-electron Auger scattering due to the nonequidistant Landau-level spacing of the Dirac fermions in graphene.

Earth's magnetic field enabled scalar coupling relaxation of 13C nuclei bound to fast-relaxing quadrupolar 14N in amide groups.

Science.gov (United States)

Chiavazza, Enrico; Kubala, Eugen; Gringeri, Concetta V; Düwel, Stephan; Durst, Markus; Schulte, Rolf F; Menzel, Marion I

2013-02-01

Scalar coupling relaxation, which is usually only associated with closely resonant nuclei (e.g., (79)Br-(13)C), can be a very effective relaxation mechanism. While working on hyperpolarized [5-(13)C]glutamine, fast liquid-state polarization decay during transfer to the MRI scanner was observed. This behavior could hypothetically be explained by substantial T(1) shortening due to a scalar coupling contribution (type II) to the relaxation caused by the fast-relaxing quadrupolar (14)N adjacent to the (13)C nucleus in the amide group. This contribution is only effective in low magnetic fields (i.e., less than 800 μT) and prevents the use of molecules bearing the (13)C-amide group as hyperpolarized MRS/MRI probes. In the present work, this hypothesis is explored both theoretically and experimentally. The results show that high hyperpolarization levels can be retained using either a (15)N-labeled amide or by applying a magnetic field during transfer of the sample from the polarizer to the MRI scanner. Copyright © 2012 Elsevier Inc. All rights reserved.

Stretched Exponential relaxation in pure Se glass

Science.gov (United States)

Dash, S.; Ravindren, S.; Boolchand, P.

A universal feature of glasses is the stretched exponential relaxation, f (t) = exp[ - t / τ ] β . The model of diffusion of excitations to randomly distributed traps in a glass by Phillips1 yields the stretched exponent β = d[d +2] where d, the effective dimensionality. We have measured the enthalpy of relaxation ΔHnr (tw) at Tg of Se glass in modulated DSC experiments as glasses age at 300K and find β = 0.43(2) for tw in the 0 relaxation is a narrowing of the glass transition width from 7.1°C to 1.4°C, and the ΔHnr term increasing from 0.21 cal/gm to 0.92 cal/gm. In bulk GexSe100-x glasses as x increases to 20%, the length of the polymeric Sen chains between the Ge-crosslinks decreases to n = 2. and the striking relaxation effects nearly vanish. J.C. Phillips, Rep.Prog.Phys. 59 , 1133 (1996). Supported by NSF Grant DMR 08-53957.

Cherenkov and anomalous Doppler effects in the relaxation of an electron beam

International Nuclear Information System (INIS)

Muschietti, L.; Appert, K.; Vaclavik, J.

1981-01-01

The interplay between the Cherenkov and anomalous Doppler interactions in the relaxation of a warm electron beam is investigated by numerical means. The most important feature in the interplay is found to be a nonelastic isotropization. A simple semianalytical model which allows one to estimate various quantities relevant to the relaxation process is also presented

Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

International Nuclear Information System (INIS)

Xu, Yuan; Cardell, Lars-Olaf

2014-01-01

Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B 2 receptor agonist) and des-Arg 9 -bradykinin- (selective B 1 receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE 2 . The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg 9 -bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B 2 receptors, but not those on B 1 . Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in some patients with asthma

Nicotine impairs cyclooxygenase-2-dependent kinin-receptor-mediated murine airway relaxations

Energy Technology Data Exchange (ETDEWEB)

Xu, Yuan, E-mail: yuan.xu@ki.se; Cardell, Lars-Olaf

2014-02-15

Introduction: Cigarette smoke induces local inflammation and airway hyperreactivity. In asthmatics, it worsens the symptoms and increases the risk for exacerbation. The present study investigates the effects of nicotine on airway relaxations in isolated murine tracheal segments. Methods: Segments were cultured for 24 h in the presence of vehicle, nicotine (10 μM) and/or dexamethasone (1 μM). Airway relaxations were assessed in myographs after pre-contraction with carbachol (1 μM). Kinin receptors, cyclooxygenase (COX) and inflammatory mediator expressions were assessed by real-time PCR and confocal-microscopy-based immunohistochemistry. Results: The organ culture procedure markedly increased bradykinin- (selective B{sub 2} receptor agonist) and des-Arg{sup 9}-bradykinin- (selective B{sub 1} receptor agonist) induced relaxations, and slightly increased relaxation induced by isoprenaline, but not that induced by PGE{sub 2}. The kinin receptor mediated relaxations were epithelium-, COX-2- and EP2-receptor-dependent and accompanied by drastically enhanced mRNA levels of kinin receptors, as well as inflammatory mediators MCP-1 and iNOS. Increase in COX-2 and mPGES-1 was verified both at mRNA and protein levels. Nicotine selectively suppressed the organ-culture-enhanced relaxations induced by des-Arg{sup 9}-bradykinin and bradykinin, at the same time reducing mPGES-1 mRNA and protein expressions. α7-nicotinic acetylcholine receptor inhibitors α-bungarotoxin and MG624 both blocked the nicotine effects on kinin B{sub 2} receptors, but not those on B{sub 1}. Dexamethasone completely abolished kinin-induced relaxations. Conclusion: It is tempting to conclude that a local inflammatory process per se could have a bronchoprotective component by increasing COX-2 mediated airway relaxations and that nicotine could impede this safety mechanism. Dexamethasone further reduced airway inflammation together with relaxations. This might contribute to the steroid resistance seen in

Impact of relaxation training according to Yoga In Daily Life® system on self-esteem after breast cancer surgery.

Science.gov (United States)

Kovačič, Tine; Kovačič, Miha

2011-12-01

The purpose of this pilot study was to gather information on the immediate and short-term effects of relaxation training according to the Yoga In Daily Life(®) system on the self-esteem of patients with breast cancer. This is a parallel-groups design. Baseline interventions took place at the Institute for Oncology of Ljubljana (Slovenia). At discharge, the experimental group was issued with audiocassette recordings containing the instructions for relaxation training to be practiced individually at home for an additional 3 weeks. The convenience sample of 32 patients with breast cancer was recruited from an accessible population of hospitalized women. Patients were randomized to the experimental (n=16) and to the control group (n=16). Both groups received the same standard physiotherapy for 1 week, while the experimental group additionally received a group relaxation training sessions according to the Yoga in Daily Life(®) system. At discharge, the experimental group was issued with audiocassette recordings containing similar instructions for relaxation training to be practiced individually at home for an additional 3 weeks. Outcome measures were obtained by blinded investigators (physiotherapists) using standardized questionnaires (Rosenberg Self-Esteem Scale) at baseline (after the surgery); at 1 week (1 week postattendance; at discharge); and at 4 weeks (4 weeks postattendance); prior the commencement of radiation. Analysis of variance showed that there were statistically significant differences between the experimental and control group in all measuring self-esteem scores over the study period (pp>0.05). The results indicate that relaxation training according to the Yoga in Daily Life system could be a useful clinical physiotherapy intervention for patients who have breast cancer and who are experiencing low self-esteem. Although this kind of relaxation training can be applied to clinical oncology in Slovenia, more studies need to be done.

Effect of Progressive Muscle Relaxation on the Adverse ...

African Journals Online (AJOL)

of PCOS patients and their influence on the cardiovascular risk factors. ... and relaxation therapies may be recommended as an adjuvant therapy, to tilt the autonomic balance to .... The fall in systolic pressure was taken as the result of orthostatic tolerance test (OTT). ... period. Group B (control group) received treatment only.

Identification of mechanisms involved in the relaxation of rabbit cavernous smooth muscle by a new nitric oxide donor ruthenium compound

Directory of Open Access Journals (Sweden)

João Batista Gadelha de Cerqueira

2012-10-01

Full Text Available PURPOSE: The aim of this study was to evaluate the relaxation in vitro of cavernous smooth muscle induced by a new NO donor of the complex nitrosil-ruthenium, named trans-[Ru(NH34(caffeine(NO]C13 (Rut-Caf and sodium nitroprusside (SNP. MATERIALS AND METHODS: The tissues, immersed in isolated bath systems, were pre-contracted with phenilephrine (PE (1 µM and then concentration-response curves (10-12 - 10-4 M were obtained. To clarify the mechanism of action involved, it was added to the baths ODQ (10 µM, 30 µM, oxyhemoglobin (10 µM, L-cysteine (100 µM, hydroxicobalamine (100 µM, glibenclamide, iberotoxin and apamine. Tissue samples were frozen in liquid nitrogen to measure the amount of cGMP and cAMP produced. RESULTS: The substances provoked significant relaxation of the cavernous smooth muscle. Both Rut-Caf and SNP determined dose-dependent relaxation with similar potency (pEC50 and maximum effect (Emax. The substances showed activity through activation of the soluble guanylyl cyclase (sGC, because the relaxations were inhibited by ODQ. Oxyhemoglobin significantly diminished the relaxation effect of the substances. L-cysteine failed to modify the relaxations caused by the agents. Hydroxicobalamine significantly diminished the relaxation effect of Rut-Caf. Glibenclamide significantly increased the efficacy of Rut-Caf (pEC50 4.09 x 7.09. There were no alterations of potency or maximum effect of the substances with the addition of the other ion channel blockers. Rut-Caf induced production of significant amounts of cGMP and cAMP during the relaxation process. CONCLUSIONS: In conclusion, Rut-Caf causes relaxation of smooth muscle of corpus cavernosum by means of activation of sGC with intracellular production of cGMP and cAMP; and also by release of NO in the intracellular environment. Rut-Caf releases the NO free radical and it does not act directly on the potassium ion channels.

Effects of contract-relax vs static stretching on stretch-induced strength loss and length-tension relationship

DEFF Research Database (Denmark)

Balle, S S; Magnusson, S P; McHugh, M P

2015-01-01

The purpose of this study was to determine the acute effects of contract-relax stretching (CRS) vs static stretching (SS) on strength loss and the length-tension relationship. We hypothesized that there would be a greater muscle length-specific effect of CRS vs SS. Isometric hamstring strength wa...

The effects of progressive muscular relaxation and breathing control technique on blood pressure during pregnancy

Directory of Open Access Journals (Sweden)

Mahboobeh Aalami

2016-01-01

Full Text Available Background: Hypertensive disorders in pregnancy are the main cause of maternal and fetal mortality; however, they have no definite effective treatment. The researchers aimed to study the effects of progressive muscular relaxation and breathing control technique on blood pressure (BP during pregnancy. Materials and Methods: This three-group clinical trial was conducted in Mashhad health centers and governmental hospitals. Sixty pregnant (after 20 weeks of gestational age women with systolic BP ≥ 135 mmHg or diastolic BP ≥ 85 mmHg were assigned to three groups. Progressive muscular relaxation and breathing control exercises were administered to the two experimental groups once a week in person and in the rest of the days by instructions given on a CD for 4 weeks. BP was checked before and after the interventions. BP was measured before and after 15 min subjects' waiting without any especial intervention in the control group. Results: After 4 weeks of intervention, the systolic (by a mean of 131.3 to 117.2, P = 0.001 and by a mean of 131.05 to 120.5, P = 0.004, respectively and diastolic (by a mean of 79.2 to 72.3, P = 0.001 and by a mean of 80.1 to 76.5, P = 0.047, respectively BPs were significantly decreased in progressive muscular relaxation and breathing control groups, but they were not statistically significant in the control group. Conclusions: The interventions were effective on decreasing systolic and diastolic BP to normal range after 4 weeks in both the groups. The effects of both the interventions were more obvious on systolic BP compared to diastolic BP.

Effect of heat treatment on bend stress relaxation of pure tungsten

International Nuclear Information System (INIS)

Sasaki, Kenta; Nogami, Shuhei; Fukuda, Makoto; Katakai, Yasuyuki; Hasegawa, Akira

2013-01-01

Highlights: • Bend stress relaxation test was performed on the pure tungsten after heat treatment for stress relief. • The BSR ratio of the heat treated specimen was larger than that of the as-received specimen at this temperature region. • Small reduction in the BSR ratio was observed at the temperatures of 500–800 °C. • The BSR ratio of the heat treated specimen decreased significantly at the temperatures of 900–1000 °C. • The BSR ratio decreased significantly in a short time below 0.1 h, and then decreased slowly. -- Abstract: Bend stress relaxation (BSR) tests at temperatures of 500, 600, 800, 900 and 1000 °C for 0.1, 0.5 and 1 h in vacuum were performed on the pure tungsten after heat treatment for stress relief at 900 °C for 1 h. The degree of stress relaxation increased with test temperature. The BSR ratio of the heat treated specimen was larger than that of the as-received specimen at this temperature region. Small reduction in the BSR ratio was observed at the temperatures of 500, 600 and 800 °C. The BSR ratio of the heat treated specimen decreased significantly at the temperatures of 900 and 1000 °C and it was close to that of the as-received specimen. The BSR ratio of the heat treated specimen and the as-received specimen exhibited similar trend of time-evolution. The stress was exponentially relaxed with increasing test time. The BSR ratio decreased significantly in a short time below 0.1 h, and then decreased slowly. Higher activation energy of stress relaxation evaluated by cross-cut method was obtained for the higher temperature

Endothelium-dependent relaxation induced by cathepsin G in porcine pulmonary arteries

Science.gov (United States)

Glusa, Erika; Adam, Christine

2001-01-01

Serine proteinases elicit profound cellular effects in various tissues mediated by activation of proteinase-activated receptors (PAR). In the present study, we investigated the vascular effects of cathepsin G, a serine proteinase that is present in the azurophil granules of leukocytes and is known to activate several cells that express PARs. In prostaglandin F2α (3 μM)-precontracted rings from porcine pulmonary arteries with intact endothelium, cathepsin G caused concentration-dependent relaxant responses (pEC50=9.64±0.12). The endothelium-dependent relaxant effect of cathepsin G could also be demonstrated in porcine coronary arteries (pEC50=9.23±0.07). In pulmonary arteries the cathepsin G-induced relaxation was inhibited after blockade of nitric oxide synthesis by L-NAME (200 μM) and was absent in endothelium-denuded vessels. Bradykinin- and cathepsin G-induced relaxant effects were associated with a 5.7 fold and 2.4 fold increase in the concentration of cyclic GMP, respectively. Compared with thrombin and trypsin, which also produced an endothelium-dependent relaxation in pulmonary arteries, cathepsin G was 2.5 and four times more potent, respectively. Cathepsin G caused only small homologous desensitization. In cathepsin G-challenged vessels, thrombin was still able to elicit a relaxant effect. The effects of cathepsin G were blocked by soybean trypsin inhibitor (IC50=0.043 μg ml−1), suggesting that proteolytic activity is essential for induction of relaxation. Recombinant acetyl-eglin C proved to be a potent inhibitor (IC50=0.14 μg ml−1) of the cathepsin G effect, whereas neither indomethacin (3 μM) nor the thrombin inhibitor hirudin (5 ATU ml−1) elicited any inhibitory activity. Due to their polyanionic structure defibrotide (IC50=0.11 μg ml−1), heparin (IC50=0.48 μg ml−1) and suramin (IC50=1.85 μg ml−1) diminished significantly the relaxation in response to the basic protein cathepsin G. In conclusion, like

Relaxation dynamics in quantum dissipative systems: The microscopic effect of intramolecular vibrational energy redistribution

Energy Technology Data Exchange (ETDEWEB)

Uranga-Piña, L. [Facultad de Física, Universidad de la Habana, San Lázaro y L, Vedado, 10400 Havana (Cuba); Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany); Tremblay, J. C., E-mail: jean.c.tremblay@gmail.com [Institute for Chemistry and Biochemistry, Freie Universität Berlin, Takustr. 3, D-14195 Berlin (Germany)

2014-08-21

We investigate the effect of inter-mode coupling on the vibrational relaxation dynamics of molecules in weak dissipative environments. The simulations are performed within the reduced density matrix formalism in the Markovian regime, assuming a Lindblad form for the system-bath interaction. The prototypical two-dimensional model system representing two CO molecules approaching a Cu(100) surface is adapted from an ab initio potential, while the diatom-diatom vibrational coupling strength is systematically varied. In the weak system-bath coupling limit and at low temperatures, only first order non-adiabatic uni-modal coupling terms contribute to surface-mediated vibrational relaxation. Since dissipative dynamics is non-unitary, the choice of representation will affect the evolution of the reduced density matrix. Two alternative representations for computing the relaxation rates and the associated operators are thus compared: the fully coupled spectral basis, and a factorizable ansatz. The former is well-established and serves as a benchmark for the solution of Liouville-von Neumann equation. In the latter, a contracted grid basis of potential-optimized discrete variable representation is tailored to incorporate most of the inter-mode coupling, while the Lindblad operators are represented as tensor products of one-dimensional operators, for consistency. This procedure results in a marked reduction of the grid size and in a much more advantageous scaling of the computational cost with respect to the increase of the dimensionality of the system. The factorizable method is found to provide an accurate description of the dissipative quantum dynamics of the model system, specifically of the time evolution of the state populations and of the probability density distribution of the molecular wave packet. The influence of intra-molecular vibrational energy redistribution appears to be properly taken into account by the new model on the whole range of coupling strengths. It

Effect of extender oils on the stress relaxation behavior of thermoplastic vulcanizates

Directory of Open Access Journals (Sweden)

2008-11-01

Full Text Available The long term mechanical behavior of oil extended thermoplastic vulcanizates (TPV based on polypropylene (PP and acrylonitrile-butadiene rubber (NBR has been characterized by means of stress relaxation experiments. The morphology of TPV and the phase specific oil distribution which depend on the content and type of oil as well as on the mixing regime have been characterized by means of Atomic Force Microscopy (AFM, Dynamic Mechanical Thermal Analysis (DMTA and Differential Scanning Calorimetrie (DSC. The discussion of the stress relaxation behavior was carried out using the two-component model, which allows splitting the initial stress into two components: a thermal activated stress component and an athermal one. A master curve was created by shifting the relaxation curves vertically and horizontally towards the reference curve. The vertical shift factor bT is a function of the temperature dependence of the athermal stress components. It was found that the oil distribution strongly affects the athermal stress component which is related to the contribution of the structural changes, e.g. crystallinity of the PP phase and the average molecular weight between the crosslinks of the NBR phase. From the temperature dependence of the horizontal shift factor aT the main viscoelastic relaxation process was determined as the α-relaxation process of the crystalline PP phase. It is not dependent on the polarity and content of the oil as well as the mixing regime.

β-adrenergic relaxation of smooth muscle: differences between cells and tissues

International Nuclear Information System (INIS)

Scheid, C.R.

1987-01-01

The present studies were carried out in an attempt to resolve the controversy about the Na + dependence of β-adrenergic relaxation in smooth muscle. Previous studies on isolated smooth muscle cells from the toad stomach had suggested that at least some of the actions of β-adrenergic agents, including a stimulatory effect on 45 Ca efflux, were dependent on the presence of a normal transmembrane Na + gradient. Studies by other investigators using tissues derived from mammalian sources had suggested that the relaxing effect of β-adrenergic agents was Na + independent. Uncertainty remained as to whether these discrepancies reflected differences between cells and tissues or differences between species. Thus, in the present studies, the authors utilized both tissues and cells from the same source, the stomach muscle of the toad Bufo marinus, and assessed the Na + dependence of β-adrenergic relaxation. They found that elimination of a normal Na + gradient abolished β-adrenergic relaxation of isolated cells. In tissues, however, similar manipulations had no effect on relaxation. The reasons for this discrepancy are unclear but do not appear to be attributable to changes in smooth muscle function following enzymatic dispersion. Thus the controversy concerning the mechanisms of β-adrenergic relaxation may reflect inherent differences between tissues and cells

Relaxation cracking in the process industry, an underestimated problem

Energy Technology Data Exchange (ETDEWEB)

Wortel, J.C. van [TNO Institute of Industrial Technology, Apeldoorn (Netherlands)

1999-12-31

Austenitic components, operating between 500 and 750 deg C, can fail within 1 year service while the ordinary mechanical properties after failure are still within the code requirements. The intergranular brittle failures are situated in the welded or cold deformed areas. This type of cracking has many names, showing the uncertainty concerning the mechanism for the (catastrophical) failures. A just finished investigation showed that it is a relaxation crack problem, introduced by manufacturing processes, especially welding and cold rolling. Cracking/failures can be expected after only 0.1- 0.2 % relaxation strain. These low strain values can already be generated during relaxation of the welding stresses. Especially coarse grained `age hardening` materials are susceptible. Stabilising and Postweld Heat Treatments are very effective to avoid relaxation crack problems during operation. After these heat treatments the components can withstand more than 2 % relaxation strain. At temperatures between 500 and 750 deg C relaxation cracking is the predominant factor for the safety and lifetime of welded austenitic components. (orig.) 12 refs.

Relaxation cracking in the process industry, an underestimated problem

Energy Technology Data Exchange (ETDEWEB)

Wortel, J.C. van [TNO Institute of Industrial Technology, Apeldoorn (Netherlands)

1998-12-31

Austenitic components, operating between 500 and 750 deg C, can fail within 1 year service while the ordinary mechanical properties after failure are still within the code requirements. The intergranular brittle failures are situated in the welded or cold deformed areas. This type of cracking has many names, showing the uncertainty concerning the mechanism for the (catastrophical) failures. A just finished investigation showed that it is a relaxation crack problem, introduced by manufacturing processes, especially welding and cold rolling. Cracking/failures can be expected after only 0.1- 0.2 % relaxation strain. These low strain values can already be generated during relaxation of the welding stresses. Especially coarse grained `age hardening` materials are susceptible. Stabilising and Postweld Heat Treatments are very effective to avoid relaxation crack problems during operation. After these heat treatments the components can withstand more than 2 % relaxation strain. At temperatures between 500 and 750 deg C relaxation cracking is the predominant factor for the safety and lifetime of welded austenitic components. (orig.) 12 refs.

Magnetic-relaxation method of analysis of inorganic substances

International Nuclear Information System (INIS)

Popel', A.A.

1978-01-01

The magnetic-relaxation method is considered of the quantitative analysis of inorganic substances based on time dependence of magnetic nuclei relaxation on the quantity of paramagnetic centres in a solution. The characteristic is given of some methods of measuring nuclear magnetic relaxation times: method of weak oscillation generator and pulse methods. The effect of temperature, general solution viscosity, diamagnetic salt concentration, medium acidity on nuclear relaxation velocity is described. The determination sensitivity is estimated and the means of its increase definable concentration intervals and method selectivity are considered. The method application when studying complexing in the solution is described. A particular attention is given to the investigation of heteroligand homocentre, heterocentre and protonated complexes as well as to the problems of particle exchange of the first coordination sphere with particles from the mass of solution. The equations for equilibrium constant calculation in different systems are given. Possibilities of determining diamagnetic ions by the magnetic-relaxation method using paramagnetic indicators are confirmed by the quantitative analysis of indium, gallium, thorium and scandium in their salt solutions

Stretched exponential relaxation in molecular and electronic glasses

International Nuclear Information System (INIS)

Phillips, J.C.

1996-01-01

Stretched exponential relaxation, exp[-(t/τ) β ], fits many relaxation processes in disordered and quenched electronic and molecular systems, but it is widely believed that this function has no microscopic basis, especially in the case of molecular relaxation. For electronic relaxation the appearance of the stretched exponential is often described in the context of dispersive transport, where β is treated as an adjustable parameter, but in almost all cases it is generally assumed that no microscopic meaning can be assigned to 0 g , a glass transition temperature. We show that for molecular relaxation β(T g ) can be understood, providing that one separates extrinsic and intrinsic effects, and that the intrinsic effects are dominated by two magic numbers, β SR =3/5 for short-range forces, and β K =3/7 for long-range Coulomb forces, as originally observed by Kohlrausch for the decay of residual charge on a Leyden jar. Our mathematical model treats relaxation kinetics using the Lifshitz-Kac-Luttinger diffusion to traps depletion model in a configuration space of effective dimensionality, the latter being determined using axiomatic set theory and Phillips-Thorpe constraint theory. The experiments discussed include ns neutron scattering experiments, particularly those based on neutron spin echoes which measure S(Q, t) directly, and the traditional linear response measurements which span the range from μs to s, as collected and analysed phenomenologically by Angell, Ngai, Boehmer and others. The electronic materials discussed include a-Si:H, granular C 60 , semiconductor nanocrystallites, charge density waves in TaS 3 , spin glasses, and vortex glasses in high-temperature semiconductors. The molecular materials discussed include polymers, network glasses, electrolytes and alcohols, Van der Waals supercooled liquids and glasses, orientational glasses, water, fused salts, and heme proteins. In the intrinsic cases the theory of β(T g ) is often accurate to 2%, which

Rouse mode analysis of chain relaxation in polymer nanocomposites.

Science.gov (United States)

Kalathi, Jagannathan T; Kumar, Sanat K; Rubinstein, Michael; Grest, Gary S

2015-05-28

Large-scale molecular dynamics simulations are used to study the internal relaxations of chains in nanoparticle (NP)/polymer composites. We examine the Rouse modes of the chains, a quantity that is closest in spirit to the self-intermediate scattering function, typically determined in an (incoherent) inelastic neutron scattering experiment. Our simulations show that for weakly interacting mixtures of NPs and polymers, the effective monomeric relaxation rates are faster than in a neat melt when the NPs are smaller than the entanglement mesh size. In this case, the NPs serve to reduce both the monomeric friction and the entanglements in the polymer melt, as in the case of a polymer-solvent system. However, for NPs larger than half the entanglement mesh size, the effective monomer relaxation is essentially unaffected for low NP concentrations. Even in this case, we observe a strong reduction in chain entanglements for larger NP loadings. Thus, the role of NPs is to always reduce the number of entanglements, with this effect only becoming pronounced for small NPs or for high concentrations of large NPs. Our studies of the relaxation of single chains resonate with recent neutron spin echo (NSE) experiments, which deduce a similar entanglement dilution effect.

Electronic relaxation of deep bulk trap and interface state in ZnO ceramics

International Nuclear Information System (INIS)

Yang Yan; Li Sheng-Tao; Ding Can; Cheng Peng-Fei

2011-01-01

This paper investigates the electronic relaxation of deep bulk trap and interface state in ZnO ceramics based on dielectric spectra measured in a wide range of temperature, frequency and bias, in addition to the steady state response. It discusses the nature of net current flowing over the barrier affected by interface state, and then obtains temperature-dependent barrier height by approximate calculation from steady I—V (current—voltage) characteristics. Additional conductance and capacitance arising from deep bulk trap relaxation are calculated based on the displacement of the cross point between deep bulk trap and Fermi level under small AC signal. From the resonances due to deep bulk trap relaxation on dielectric spectra, the activation energies are obtained as 0.22 eV and 0.35 eV, which are consistent with the electronic levels of the main defect interstitial Zn and vacancy oxygen in the depletion layer. Under moderate bias, another resonance due to interface relaxation is shown on the dielectric spectra. The DC-like conductance is also observed in high temperature region on dielectric spectra, and the activation energy is much smaller than the barrier height in steady state condition, which is attributed to the displacement current coming from the shallow bulk trap relaxation or other factors. (fluids, plasmas and electric discharges)

Stress Relaxation Effects in TiNi SMA During Superelastic Deformation: Experiment and Constitutive Model

Science.gov (United States)

Pieczyska, Elżbieta A.; Kowalewski, Zbigniew L.; Dunić, Vladimir Lj.

2017-12-01

This paper presents an investigation of thermomechanical effects related to the phenomena of stress relaxation occurring in TiNi SMA subjected to modified program of displacement-controlled tension. The deformation data were taken from testing machine, whereas the temperature changes accompanying the exothermic/endothermic martensite forward/reverse transformation were measured by infrared camera. At the advanced stages of the transformations, the strain was kept constant for a few minutes and the SMA load and temperature were recorded continuously. As a consequence, the stress and temperature changed significantly during the loading stops. A large stress drop, caused by the transformation, was observed during the relaxation stage in both courses of the SMA loading and unloading. Moreover, the non-uniform temperature distribution, reflecting macroscopically inhomogeneous transformation, lapsed while the strain was kept constant, yet restarted at the end of the relaxation stop and developed at the reloading stage. Along with the experimental results, the mechanical and thermal responses induced by the transformation were obtained by 3D coupled thermomechanical numerical analysis, realized in partitioned approach. Latent heat production was correlated with an amount of the martensitic volume fraction. The stress and temperature drops recorded during the experiment were satisfactorily reproduced by the model proposed for the SMA thermomechanical coupling.

Spin relaxation and the Kondo effect in transition metal dichalcogenide monolayers

International Nuclear Information System (INIS)

Rostami, Habib; Moghaddam, Ali G; Asgari, Reza

2016-01-01

We investigate the spin relaxation and Kondo resistivity caused by magnetic impurities in doped transition metal dichalcogenide monolayers. We show that momentum and spin relaxation times, due to the exchange interaction by magnetic impurities, are much longer when the Fermi level is inside the spin-split region of the valence band. In contrast to the spin relaxation, we find that the dependence of Kondo temperature T K on the doping is not strongly affected by the spin–orbit induced splitting, although only one of the spin species are present at each valley. This result, which is obtained using both perturbation theory and the poor man’s scaling methods, originates from the intervalley spin-flip scattering in the spin-split region. We further demonstrate the decline in the conductivity with temperatures close to T K , which can vary with the doping. Our findings reveal the qualitative difference with the Kondo physics in conventional metallic systems and other Dirac materials. (paper)

Dynamics of helicity transport and Taylor relaxation

International Nuclear Information System (INIS)

Diamond, P.H.; Malkov, M.

2003-01-01

A simple model of the dynamics of Taylor relaxation is derived using symmetry principles alone. No statistical closure approximations are invoked or detailed plasma model properties assumed. Notably, the model predicts several classes of nondiffusive helicity transport phenomena, including traveling nonlinear waves and superdiffusive turbulent pulses. A universal expression for the scaling of the effective magnetic Reynolds number of a system undergoing Taylor relaxation is derived. Some basic properties of intermittency in helicity transport are examined

Relaxation and Diffusion in Complex Systems

CERN Document Server

Ngai, K L

2011-01-01

Relaxation and Diffusion in Complex Systems comprehensively presents a variety of experimental evidences of universal relaxation and diffusion properties in complex materials and systems. The materials discussed include liquids, glasses, colloids, polymers, rubbers, plastic crystals and aqueous mixtures, as well as carbohydrates, biomolecules, bioprotectants and pharmaceuticals. Due to the abundance of experimental data, emphasis is placed on glass-formers and the glass transition problem, a still unsolved problem in condensed matter physics and chemistry. The evidence for universal properties of relaxation and diffusion dynamics suggests that a fundamental physical law is at work. The origin of the universal properties is traced to the many-body effects of the interaction, rigorous theory of which does not exist at the present time. However, using solutions of simplified models as guides, key quantities have been identified and predictions of the universal properties generated. These predictions from Ngai’...

Hysteresis in magnetic materials: the role of structural disorder, thermal relaxation, and dynamic effects

International Nuclear Information System (INIS)

Bertotti, G.; Basso, V.; Beatrice, C.; LoBue, M.; Magni, A.; Tiberto, P.

2001-01-01

An overview is given of the present understanding of hysteresis phenomena in magnetic materials. The problem is addressed from three approximate viewpoints: the connection between rate-independent hysteresis and micromagnetics; the modifications brought into this picture by thermal relaxation effects; the role of rate-dependent magnetization mechanisms, like eddy-current-damped domain wall motion

Music preference and relaxation in Taiwanese elderly people.

Science.gov (United States)

Lai, Hui-Ling

2004-01-01

The purpose of this study was to identify individual musical preferences, investigate the relationship between an individual's musical preferences and demographic variables, and examine the effects of the selected music on relaxation. Fifty healthy subjects (mean age 65.7; SD = 5.2) from the community participated in the study. Musical preference interviews and relaxed responses to selected music were administered to the study participants individually in the investigator's office. Participants' heart rates, respiratory rates, and finger temperature were measured before they listened to the introductory tape and again after they listened to the selected music for 20 minutes. The participants were asked to judge how much they liked the 6 types of soothing music and were asked to rate it on a scale. The results indicated that Chinese orchestral music was the preferred choice, followed by harp, piano, synthesizer, orchestral, and finally slow jazz. There were no differences among types of music on relaxation, and no significant differences between musical preference and any demographic variables. The heart rates and respiratory rates of the participants were significantly lower (t = 21.24, P music. These findings suggest that soothing music selections have beneficial effects on relaxation in community-residing elderly people.

Effects of music listening and relaxation instructions on arousal changes and the working memory task in older adults.

Science.gov (United States)

Hirokawa, Eri

2004-01-01

The purpose of this study was to examine the effects of subject-preferred music and relaxation instructions on older adults' arousal and working memory. Fifteen female older adults participated in 10 minutes of all 3 experimental conditions: (a) subject-preferred music, (b) relaxation instructions, and (c) silence control. Four subcategories of arousal level, energy, tiredness, tension, and calmness, were measured before and after experimental treatment using the Activation-Deactivation Adjective Check List by Thayer (1978). After each experimental condition, subjects had a working memory test by Daneman and Carpenter (1980). Results of the 2 x 3 repeated measures analysis of variances indicated that music increased subjects' energy levels, but relaxation and silence significantly decreased energy levels. Relaxation and silence increased their tiredness and calmness levels. All experimental conditions decreased subjects' tension levels. The scores in the working memory test were not significantly different among experimental conditions. Results did not indicate clear relationships between four subcategories of arousal levels and working memory scores. Results indicated that subject-preferred music has potentials to increase older adults' energetic arousal and reduce tension.

Local lattice relaxations in random metallic alloys: Effective tetrahedron model and supercell approach

DEFF Research Database (Denmark)

Ruban, Andrei; Simak, S.I.; Shallcross, S.

2003-01-01

We present a simple effective tetrahedron model for local lattice relaxation effects in random metallic alloys on simple primitive lattices. A comparison with direct ab initio calculations for supercells representing random Ni0.50Pt0.50 and Cu0.25Au0.75 alloys as well as the dilute limit of Au-ri......-rich CuAu alloys shows that the model yields a quantitatively accurate description of the relaxtion energies in these systems. Finally, we discuss the bond length distribution in random alloys....

Relaxation effects in oxygen-conducting oxides on base of lanthanum gallate (La, Sr)(Ga, Me)O3, Me = Mg, Fe

International Nuclear Information System (INIS)

Glavatskikh, T.Yu.; Venskovskij, N.U.; Kaleva, G.M.; Mosunov, A.V.; Politova, E.D.; Stefanovich, S.Yu.

2003-01-01

The dielectric and electric conducting properties of the heterosubstituted perovskite-like solid solutions (La, Sr)(Ga, Me)O 3 , Me Mg, Fe are studied. The increase in the ceramics electric conductivity, conditioned by increase in the ion constituent at strengthening the nonstoichiometry by oxygen and electron constituent by the additional introduction of iron is observed by replacing the part of the lanthanum and gallium cations by strontium, magnesium and iron in the solid solutions on the basis of the lanthanum gallate. The ceramics relaxation behavior is identified; the applicability of the model of the vacational electron transfer for the dipole relaxation is established [ru

Effects of pulmonary inhalation on hyperpolarized krypton-83 magnetic resonance T1 relaxation.

Science.gov (United States)

Stupic, K F; Elkins, N D; Pavlovskaya, G E; Repine, J E; Meersmann, T

2011-07-07

The (83)Kr magnetic resonance (MR) relaxation time T(1) of krypton gas in contact with model surfaces was previously found to be highly sensitive to surface composition, surface-to-volume ratio, and surface temperature. The work presented here explored aspects of pulmonary (83)Kr T(1) relaxation measurements in excised lungs from healthy rats using hyperpolarized (hp) (83)Kr with approximately 4.4% spin polarization. MR spectroscopy without spatial resolution was applied to the ex vivo lungs that actively inhale hp (83)Kr through a custom designed ventilation system. Various inhalation schemes were devised to study the influence of anatomical dead space upon the measured (83)Kr T(1) relaxation times. The longitudinal (83)Kr relaxation times in the distal airways and the respiratory zones were independent of the lung inhalation volume, with T(1) = 1.3 s and T(1) = 1.0 s, depending only on the applied inhalation scheme. The obtained data were highly reproducible between different specimens. Further, the (83)Kr T(1) relaxation times in excised lungs were unaffected by the presence of up to 40% oxygen in the hp gas mixture. The results support the possible importance of (83)Kr as a biomarker for evaluating lung function.

Group hypnotherapy versus group relaxation for smoking cessation: an RCT study protocol

Directory of Open Access Journals (Sweden)

Dickson-Spillmann Maria

2012-04-01

Full Text Available Abstract Background A significant number of smokers would like to stop smoking. Despite the demonstrated efficacy of pharmacological smoking cessation treatments, many smokers are unwilling to use them; however, they are inclined to try alternative methods. Hypnosis has a long-standing reputation in smoking cessation therapy, but its efficacy has not been scientifically proven. We designed this randomised controlled trial to evaluate the effects of group hypnosis as a method for smoking cessation, and we will compare the results of group hypnosis with group relaxation. Methods/Design This is a randomised controlled trial (RCT to compare the efficacy of a single session of hypnosis with that of relaxation performed in groups of 8-15 smokers. We intend to include at least 220 participants in our trial. The inclusion criteria include smoking at least 5 cigarettes per day, not using other cessation methods and being willing to quit smoking. The intervention is performed by a trained hypnotist/relaxation therapist. Both groups first receive 40 min of mental preparation that is based on motivational interviewing. Then, a state of deep relaxation is induced in the hypnosis condition, and superficial relaxation is induced in the control condition. Suggestions are made in the hypnosis condition that aim to switch the mental self-image of the participants from that of smokers to that of non-smokers. Each intervention lasts for 40 min. The participants also complete questionnaires that assess their smoking status and symptoms of depression and anxiety at baseline, 2 weeks and 6 months post-intervention. In addition, saliva samples are collected to assess cotinine levels at baseline and at 6 months post-intervention. We also assess nicotine withdrawal symptoms at 2 weeks post-intervention. Discussion To the best of our knowledge, this RCT is the first to test the efficacy of group hypnosis versus group relaxation. Issues requiring discussion in the outcome

TEACHING NEUROMUSCULAR RELAXATION.

Science.gov (United States)

NORRIS, JEANNE E.; STEINHAUS, ARTHUR H.

THIS STUDY ATTEMPTED TO FIND OUT WHETHER (1) THE METHODS FOR ATTAINING NEUROMUSCULAR RELAXATION THAT HAVE PROVED FRUITFUL IN THE ONE-TO-ONE RELATIONSHIP OF THE CLINIC CAN BE SUCCESSFULLY ADAPTED TO THE TEACHER-CLASS RELATIONSHIP OF THE CLASSROOM AND GYMNASIUM, AND (2) NEUROMUSCULAR RELAXATION CAN BE TAUGHT SUCCESSFULLY BY AN APPROPRIATELY TRAINED…

Relaxation training for anxiety: a ten-years systematic review with meta-analysis.

Science.gov (United States)

Manzoni, Gian Mauro; Pagnini, Francesco; Castelnuovo, Gianluca; Molinari, Enrico

2008-06-02

Relaxation training is a common treatment for anxiety problems. Lacking is a recent quantitative meta-analysis that enhances understanding of the variability and clinical significance of anxiety reduction outcomes after relaxation treatment. All studies (1997-2007), both RCT, observational and without control group, evaluating the efficacy of relaxation training (Jacobson's progressive relaxation, autogenic training, applied relaxation and meditation) for anxiety problems and disorders were identified by comprehensive electronic searches with Pubmed, Psychinfo and Cochrane Registers, by checking references of relevant studies and of other reviews. Our primary outcome was anxiety measured with psychometric questionnaires. Meta-analysis was undertaken synthesizing the data from all trials, distinguishing within and between effect sizes. 27 studies qualified for the inclusion in the meta-analysis. As hypothesized, relaxation training showed a medium-large effect size in the treatment of anxiety. Cohen's d was .57 (95% CI: .52 to .68) in the within analysis and .51 (95% CI: .46 to .634) in the between group analysis. Efficacy was higher for meditation, among volunteers and for longer treatments. Implications and limitations are discussed. The results show consistent and significant efficacy of relaxation training in reducing anxiety. This meta-analysis extends the existing literature through facilitation of a better understanding of the variability and clinical significance of anxiety improvement subsequent to relaxation training.

An Electron/Photon/Relaxation Data Library for MCNP6

Energy Technology Data Exchange (ETDEWEB)

Hughes, III, H. Grady [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-08-07

The capabilities of the MCNP6 Monte Carlo code in simulation of electron transport, photon transport, and atomic relaxation have recently been significantly expanded. The enhancements include not only the extension of existing data and methods to lower energies, but also the introduction of new categories of data and methods. Support of these new capabilities has required major additions to and redesign of the associated data tables. In this paper we present the first complete documentation of the contents and format of the new electron-photon-relaxation data library now available with the initial production release of MCNP6.

Efficient modified Jacobi relaxation for minimizing the energy functional

International Nuclear Information System (INIS)

Park, C.H.; Lee, I.; Chang, K.J.

1993-01-01

We present an efficient scheme of diagonalizing large Hamiltonian matrices in a self-consistent manner. In the framework of the preconditioned conjugate gradient minimization of the energy functional, we replace the modified Jacobi relaxation for preconditioning and use for band-by-band minimization the restricted-block Davidson algorithm, in which only the previous wave functions and the relaxation vectors are included additionally for subspace diagonalization. Our scheme is found to be comparable with the preconditioned conjugate gradient method for both large ordered and disordered Si systems, while it is more rapidly converged for systems with transition-metal elements

Longitudinal relaxation of initially straight flexible and stiff polymers

Science.gov (United States)

Dimitrakopoulos, Panagiotis; Dissanayake, Inuka

2004-11-01

The present talk considers the relaxation of a single flexible or stiff polymer chain from an initial straight configuration in a viscous solvent. This problem commonly arises when strong flows are turned off in both industrial and biological applications. The problem is also motivated by recent experiments with single biopolymer molecules relaxing after being fully extended by applied forces as well as by the recent development of micro-devices involving stretched tethered biopolymers. Our results are applicable to a wide array of synthetic polymers such as polyacrylamides, Kevlar and polyesters as well as biopolymers such as DNA, actin filaments, microtubules and MTV. In this talk we discuss the mechanism of the polymer relaxation as was revealed through Brownian Dynamics simulations covering a broad range of time scales and chain stiffness. After the short-time free diffusion, the chain's longitudinal reduction at early intermediate times is shown to constitute a universal behavior for any chain stiffness caused by a quasi-steady relaxation of tensions associated with the deforming action of the Brownian forces. Stiff chains are shown to exhibit a late intermediate-time longitudinal reduction associated with a relaxation of tensions affected by the deforming Brownian and the restoring bending forces. The longitudinal and transverse relaxations are shown to obey different laws, i.e. the chain relaxation is anisotropic at all times. In the talk, we show how from the knowledge of the relaxation mechanism, we can predict and explain the polymer properties including the polymer stress and the solution birefringence. In addition, a generalized stress-optic law is derived valid for any time and chain stiffness. All polymer properties which depend on the polymer length are shown to exhibit two intermediate-time behaviors with the early one to constitute a universal behavior for any chain stiffness. This work was supported in part by the Minta Martin Research Fund. The

Relaxation of the magnetization in magnetic molecules

Science.gov (United States)

Carretta, S.; Bianchi, A.; Liviotti, E.; Santini, P.; Amoretti, G.

2006-04-01

Several mechanisms characterize the relaxation dynamics in magnetic molecules. We investigate two of them, spin-lattice coupling and incoherent quantum tunneling. The effect of the phonon heat bath is studied by analyzing the exponential time decay of the autocorrelation of the magnetization. We show that in ferromagnetic (Cu6) and antiferromagnetic (Fe6) molecular rings this decay is characterized by a single characteristic time. At very low temperature, relaxation through incoherent quantum tunneling may occur in nanomagnets such as Fe8 or Ni4. The mixing between levels with different values of the total spin (S mixing) greatly influences this mechanism. In particular, we demonstrate that a fourth-order anisotropy term O44, required to interpret experimental electron paramagnetic resonance and relaxation data in Ni4, naturally arises when S mixing is considered in calculations.

Logarithmic superposition of force response with rapid length changes in relaxed porcine airway smooth muscle.

Science.gov (United States)

Ijpma, G; Al-Jumaily, A M; Cairns, S P; Sieck, G C

2010-12-01

We present a systematic quantitative analysis of power-law force relaxation and investigate logarithmic superposition of force response in relaxed porcine airway smooth muscle (ASM) strips in vitro. The term logarithmic superposition describes linear superposition on a logarithmic scale, which is equivalent to multiplication on a linear scale. Additionally, we examine whether the dynamic response of contracted and relaxed muscles is dominated by cross-bridge cycling or passive dynamics. The study shows the following main findings. For relaxed ASM, the force response to length steps of varying amplitude (0.25-4% of reference length, both lengthening and shortening) are well-fitted with power-law functions over several decades of time (10⁻² to 10³ s), and the force response after consecutive length changes is more accurately fitted assuming logarithmic superposition rather than linear superposition. Furthermore, for sinusoidal length oscillations in contracted and relaxed muscles, increasing the oscillation amplitude induces greater hysteresivity and asymmetry of force-length relationships, whereas increasing the frequency dampens hysteresivity but increases asymmetry. We conclude that logarithmic superposition is an important feature of relaxed ASM, which may facilitate a more accurate prediction of force responses in the continuous dynamic environment of the respiratory system. In addition, the single power-function response to length changes shows that the dynamics of cross-bridge cycling can be ignored in relaxed muscle. The similarity in response between relaxed and contracted states implies that the investigated passive dynamics play an important role in both states and should be taken into account.

Criteria for accurate determination of the magnon relaxation length from the nonlocal spin Seebeck effect

NARCIS (Netherlands)

Shan, Juan; Cornelissen, Ludo Johannes; Liu, Jing; Ben Youssef, J.; Liang, Lei; van Wees, Bart

2017-01-01

The nonlocal transport of thermally generated magnons not only unveils the underlying mechanism of the spin Seebeck effect, but also allows for the extraction of the magnon relaxation length (λm) in a magnetic material, the average distance over which thermal magnons can propagate. In this study, we

Uridine Adenosine Tetraphosphate-Induced Coronary Relaxation Is Blunted in Swine With Pressure Overload: A Role for Vasoconstrictor Prostanoids.

Science.gov (United States)

Zhou, Zhichao; Lankhuizen, Inge M; van Beusekom, Heleen M; Cheng, Caroline; Duncker, Dirk J; Merkus, Daphne

2018-01-01

Plasma levels of the vasoactive substance uridine adenosine tetraphosphate (Up 4 A) are elevated in hypertensive patients and Up 4 A-induced vascular contraction is exacerbated in various arteries isolated from hypertensive animals, suggesting a potential role of Up 4 A in development of hypertension. We previously demonstrated that Up 4 A produced potent and partially endothelium-dependent relaxation in the porcine coronary microvasculature. Since pressure-overload is accompanied by structural abnormalities in the coronary microvasculature as well as by endothelial dysfunction, we hypothesized that pressure-overload blunts the coronary vasodilator response to Up 4 A, and that the involvement of purinergic receptors and endothelium-derived factors is altered. The effects of Up 4 A were investigated using wire-myography in isolated coronary small arteries from Sham-operated swine and swine with prolonged (8 weeks) pressure overload of the left ventricle induced by aortic banding (AoB). Expression of purinergic receptors and endothelium-derived factors was assessed in isolated coronary small arteries using real-time PCR. Up 4 A (10 -9 to 10 -5 M) failed to produce contraction in isolated coronary small arteries from either Sham or AoB swine, but produced relaxation in preconstricted arteries, which was significantly blunted in AoB compared to Sham. Blockade of purinergic P1, and P2 receptors attenuated Up 4 A-induced coronary relaxation more, while the effect of P2X 1 -blockade was similar and the effects of A 2A - and P2Y 1 -blockade were reduced in AoB as compared to Sham. mRNA expression of neither A1, A2, A3, nor P2X 1 , P2X 7 , P2Y 1 , P2Y 2 , nor P2Y 6 -receptors was altered in AoB as compared to Sham, while P2Y 12 expression was higher in AoB. eNOS inhibition attenuated Up 4 A-induced coronary relaxation in both Sham and AoB. Additional blockade of cyclooxygenase enhanced Up 4 A-induced coronary relaxation in AoB but not Sham swine, suggesting the involvement

Activation of muscarinic receptors by a hydroalcoholic extract of Dicksonia sellowiana Presl. HooK (Dicksoniaceae) induces vascular relaxation and hypotension in rats.

Science.gov (United States)

Rattmann, Yanna D; Crestani, Sandra; Lapa, Fernanda R; Miguel, Obdúlio G; Marques, Maria C A; da Silva-Santos, J Eduardo; Santos, Adair R S

2009-01-01

Dicksonia sellowiana (Presl.) Hook is a native plant from the Central and South Americas that contain high levels of polyphenols, antioxidant compounds involved in protection against inflammation, cancer and cardiovascular risk. A phytomedicinal preparation obtained from aerial parts of D. sellowiana is currently under clinical evaluation in Brazil against asthma, and has been associated with several other beneficial effects. This study demonstrates that a hydroalcoholic extract obtained from D. sellowiana leaves (HEDS) fully relax, in a concentration-dependent manner, rat aortic rings precontracted with phenylephrine. Moreover, administration of HEDS (10, 20 and 40 mg/kg, i.v.) in anaesthetized rats resulted in a strong but reversible hypotension. Aortic relaxation induced by HEDS was abolished by endothelium removal, by incubation of the nitric oxide synthase inhibitor L-NAME, or the soluble guanylate cyclase inhibitor ODQ. In addition, this effect was partially inhibited by indomethacin (a cyclooxygenase inhibitor) and KT 5730 (a PKA inhibitor). The potassium channels blockade by either tetraethylammonium or charybdotoxin also resulted in a potent inhibition of HEDS-induced aortic relaxation, whereas apamine only slightly reduced it. In addition HEDS-induced relaxation was unchanged by 4-amynopiridine and glibenclamide. The selective muscarinic receptor antagonist atropine counteracted both aortic relaxation and blood pressure reduction generated by HEDS. Experiments using HPLC revealed the presence of high amounts of phenolic compounds in this extract. Taken together, our results reveal that the D. sellowiana possess substances with both in vivo and in vitro activities and that the vascular effect of HEDS involves activation of muscarinic receptors, stimulation of the nitric oxide pathway and opening of calcium-activated potassium channels.

Second-order Monte Carlo wave-function approach to the relaxation effects on ringing revivals in a molecular system interacting with a strongly squeezed coherent field

International Nuclear Information System (INIS)

Nakano, Masayoshi; Kishi, Ryohei; Nitta, Tomoshige; Yamaguchi, Kizashi

2004-01-01

We investigate the relaxation effects on the quantum dynamics in a two-state molecular system interacting with a single-mode strongly amplitude-squeezed coherent field using the second-order Monte Carlo wave-function method. The molecular population inversion (collapse-revival behavior of Rabi oscillations) is known to show the echoes after each revival, which are referred to as ringing revivals, in the case of strongly squeezed coherent fields with oscillatory photon-number distributions due to the phase-space interference effect. Two types of relaxation effects, i.e., cavity relaxation (the dissipation of an internal single mode to outer mode) and molecular coherent (phase) relaxation caused by nuclear vibrations on ringing revivals are investigated from the viewpoint of the quantum-phase dynamics using the quasiprobability (Q function) distribution of a single-mode field and the off-diagonal molecular density matrix ρ elec1,2 (t). It turns out that the molecular phase relaxation attenuates both the entire revival-collapse behavior and the increase in ρ elec1,2 (t) during the quiescent region, whereas a very slight cavity relaxation particularly suppresses the echoes in ringing revivals more significantly than the first revival but hardly changes a primary variation in envelope of ρ elec1,2 (t) in the nonrelaxation case

Effects of electron correlation, exchange, and relaxation on x-ray, Auger, and Coster-Kronig transitions

International Nuclear Information System (INIS)

Karim, K.R.

1983-01-01

The first topic deals with Auger and radiative deexcitation of highly stripped phosphorus atoms. X-ray wavelengths, Auger energies, and decay rates have been calculated for various states of the P 4+ ion, with configurations (1s 2 2s 2 2p 5 )3s3p, 3s3d, 3s 2 , 3p 2 , and 3d 2 . Intermediate coupling and configuration interaction have been taken into account. The energies and decay rates are found to be strongly affected by configuration interaction. The theoretical results are compared with recent observations in ion-atom collision experiments. Good agreement with measured spectra is found, and the calculations characterize a number of lines that had not previously been identified. The second topic relates to the effects of exchange, relaxation, and electron correlation on the L 1 -L 23 M 1 Coster-Kronig spectrum of argon. The present calculation leads to good agreement with experimental transition energies and removes some of the discrepancies in transition rates. The total calculated transition rates are still about a factor of two higher than the measured rates. Relaxation tends to minimize the differences between individual L 1 -L 23 M 1 ( 1 P) and L 1 -L 23 M 1 ( 3 P) transition rates. The initial- and final-ionic-configuration interaction reduces the total decay rate by approx.35%. Inclusion of complete relaxation increases the total rate, however, by approx.1.5% rather than reducing it, with respect to calculations without relaxation. The exchange interaction also increases this rate by approx.9%

Stress-relaxation behavior of lignocellulosic high-density polyethlene composites

Science.gov (United States)

Babak Mirzaei; Mehdi Tajvidi; Robert H. Falk; Colin Felton

2011-01-01

In this study, stress-relaxation performance of HDPE-based injection-molded composites containing four types of natural fibers (i.e., wood flour, rice hulls, newsprint, and kenaf fiber) at 25 and 50 wt% contents, and the effect of prescribed strain levels were investigated. The results indicated that incorporating more filler causes lower relaxation values and rates,...

Spin transport and relaxation in graphene

International Nuclear Information System (INIS)

Han Wei; McCreary, K.M.; Pi, K.; Wang, W.H.; Li Yan; Wen, H.; Chen, J.R.; Kawakami, R.K.

2012-01-01

We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for

The effects of the contract-relax-antagonist-contract form of proprioceptive neuromuscular facilitation stretching on postural stability.

Science.gov (United States)

Ryan, Edwin E; Rossi, Mark D; Lopez, Richard

2010-07-01

To investigate the effects of the contract-relax-antagonist-contract (CRAC) form of proprioceptive neuromuscular facilitation (PNF) stretching, with and without a warm-up, on postural stability. Thirty volunteers (15 men and 15 women, age: 25.17 +/- 5.4 years, height: 173.76 +/- 8.2 cm, and weight: 72.03 +/- 14.87 kg) were randomly assigned to 1 of 3 conditions: warm-up and stretch (WS), stretching only (SO), and a control condition (CON). Contract-relax-antagonist-contract PNF of the hamstrings, plantar flexors, and hip flexors was performed during WS and SO. A 6-minute treadmill warm-up was applied before CRAC in the WS condition. Measures of anterior/posterior and medial/lateral (M/L) postural stability were taken before and after treatment conditions. A 2 x 3 analysis of variance was used to assess for differences between conditions. Significance was set at p Contract-relax-antagonist-contract form of stretching is a useful protocol for improving M/L stability.

Sodium pump activity and calcium relaxation in vascular smooth muscle of deoxycorticosterone acetate-salt rats

International Nuclear Information System (INIS)

Soltis, E.E.; Field, F.P.

1986-01-01

The Na + -K + pump activity was determined in femoral arterial smooth muscle from deoxycorticosterone acetate (DOCA)-salt hypertensive rats using potassium relaxation and ouabain-sensitive 86 Rb uptake as indices. The membrane-stabilizing effect of calcium and its relation to Na + -K + pump activity also were examined. Femoral arteries from DOCA-salt rats exhibited a greater relaxation in response to potassium addition after contraction with norepinephrine in a low potassium (0.6 mM) Krebs solution. The concentration of potassium required to produce a 50% relaxation was significantly less in DOCA-salt rats. Ouabain-sensitive 86 Rb uptake was significantly greater at 3, 10, and 20 minutes of 86 Rb incubation in femoral arteries from DOCA-salt rats. Linear regression analysis revealed a significant correlation between the uptake of 86 Rb and time of incubation in both control and DOCA-salt rats. A significant difference in the slopes of the regression lines showed that the rate of uptake was greater in DOCA-salt rats. No difference was observed in ouabain-insensitive 86 Rb uptake. A dose-dependent relaxation in response to increasing concentrations of calcium following contraction to norepinephrine was observed in femoral arteries from control and DOCA-salt rats. The relaxation was directly dependent on the level of extracellular potassium and was blocked by ouabain. Femoral arteries from DOCA-salt rats relaxed to a significantly greater extent in response to calcium at each level of potassium when compared with controls. These results provide further evidence for an increase in Na + -K + pump activity in vascular smooth muscle from DOCA-salt hypertensive rats

Magnetic relaxation in anisotropic magnets

DEFF Research Database (Denmark)

Lindgård, Per-Anker

1971-01-01

The line shape and the kinematic and thermodynamic slowing down of the critical and paramagnetic relaxation in axially anisotropic materials are discussed. Kinematic slowing down occurs only in the longitudinal relaxation function. The thermodynamic slowing down occurs in either the transverse...... or longitudinal relaxation function depending on the sign of the axial anisotropy....

Effects of pair correlation functions on intermolecular nuclear relaxation by translational and rotational diffusion in liquids

International Nuclear Information System (INIS)

Fries, P.

1978-01-01

In order to study the intermolecular relaxation due to magnetic dipolar interactions, we calculate the spectral densities resulting from random translational and rotational motions of spherical molecules carrying off-centre spins. The relative translational motion is treated in the frame-work of a general diffusion equation (the Smoluchowski equation) which takes into account the existence of effective forces between the molecules. This model implies a pair correlation function. i.e. a non unifom relative distribution of the molecules. The analytical calculations are carried out by taking correctly into account the hard sphere boundary conditions for the molecules. Explicit numerical calculations of the spectral densities are performed using finite difference methods and the pair correlation function of Verlet and Weiss obtained by computer experiments. The resulting calculations allow one to interpret the relaxation exhibited by benzene and some of its monohalogen derivatives which has been measured by Jonas et al. at various pressures. The effects of pair correlation and eccentricity contribute to a noticeable enhancement of the spectral densities, especially as the frequency increases. The translational correlation times calculated from the Stokes formula and those deduced from intermolecular relaxation studies are compared. It is shown that in order to distinguish which of the dynamical models is appropriate, measurements must be made as a function of frequency [fr

Nonlocal and collective relaxation in stellar systems

Science.gov (United States)

Weinberg, Martin D.

1993-01-01

The modal response of stellar systems to fluctuations at large scales is presently investigated by means of analytic theory and n-body simulation; the stochastic excitation of these modes is shown to increase the relaxation rate even for a system which is moderately far from instability. The n-body simulations, when designed to suppress relaxation at small scales, clearly show the effects of large-scale fluctuations. It is predicted that large-scale fluctuations will be largest for such marginally bound systems as forming star clusters and associations.

Relaxation training for anxiety: a ten-years systematic review with meta-analysis

Science.gov (United States)

Manzoni, Gian Mauro; Pagnini, Francesco; Castelnuovo, Gianluca; Molinari, Enrico

2008-01-01

Background Relaxation training is a common treatment for anxiety problems. Lacking is a recent quantitative meta-analysis that enhances understanding of the variability and clinical significance of anxiety reduction outcomes after relaxation treatment. Methods All studies (1997–2007), both RCT, observational and without control group, evaluating the efficacy of relaxation training (Jacobson's progressive relaxation, autogenic training, applied relaxation and meditation) for anxiety problems and disorders were identified by comprehensive electronic searches with Pubmed, Psychinfo and Cochrane Registers, by checking references of relevant studies and of other reviews. Our primary outcome was anxiety measured with psychometric questionnaires. Meta-analysis was undertaken synthesizing the data from all trials, distinguishing within and between effect sizes. Results 27 studies qualified for the inclusion in the meta-analysis. As hypothesized, relaxation training showed a medium-large effect size in the treatment of anxiety. Cohen's d was .57 (95% CI: .52 to .68) in the within analysis and .51 (95% CI: .46 to .634) in the between group analysis. Efficacy was higher for meditation, among volunteers and for longer treatments. Implications and limitations are discussed. Conclusion The results show consistent and significant efficacy of relaxation training in reducing anxiety. This meta-analysis extends the existing literature through facilitation of a better understanding of the variability and clinical significance of anxiety improvement subsequent to relaxation training. PMID:18518981

Relaxation training for anxiety: a ten-years systematic review with meta-analysis

Directory of Open Access Journals (Sweden)

Castelnuovo Gianluca

2008-06-01

Full Text Available Abstract Background Relaxation training is a common treatment for anxiety problems. Lacking is a recent quantitative meta-analysis that enhances understanding of the variability and clinical significance of anxiety reduction outcomes after relaxation treatment. Methods All studies (1997–2007, both RCT, observational and without control group, evaluating the efficacy of relaxation training (Jacobson's progressive relaxation, autogenic training, applied relaxation and meditation for anxiety problems and disorders were identified by comprehensive electronic searches with Pubmed, Psychinfo and Cochrane Registers, by checking references of relevant studies and of other reviews. Our primary outcome was anxiety measured with psychometric questionnaires. Meta-analysis was undertaken synthesizing the data from all trials, distinguishing within and between effect sizes. Results 27 studies qualified for the inclusion in the meta-analysis. As hypothesized, relaxation training showed a medium-large effect size in the treatment of anxiety. Cohen's d was .57 (95% CI: .52 to .68 in the within analysis and .51 (95% CI: .46 to .634 in the between group analysis. Efficacy was higher for meditation, among volunteers and for longer treatments. Implications and limitations are discussed. Conclusion The results show consistent and significant efficacy of relaxation training in reducing anxiety. This meta-analysis extends the existing literature through facilitation of a better understanding of the variability and clinical significance of anxiety improvement subsequent to relaxation training.

Effect of cycling on oxygenation of relaxed neck/shoulder muscles in women with and without chronic pain

DEFF Research Database (Denmark)

Andersen, Lars L; Blangsted, Anne Katrine; Nielsen, Pernille Kofoed

2010-01-01

Work-related neck/shoulder muscle pain has been associated with increased anaerobic muscle metabolism. Thus, interventions to enhance oxygenation of painful muscles seem relevant. While cycling with relaxed shoulders has been shown to result in acute neck/shoulder muscle pain reduction, the effect...... on tissue oxygenation remains unknown. The aim of the present study was to investigate tissue oxygenation of the passive trapezius muscle during and after cycling in female workers with (MYA) and without (CON) trapezius myalgia. Eligible participants (n = 17 MYA, n = 8 CON) performed 20 min sub...... increases oxygenation of resting neck/shoulder muscles in women with and without trapezius myalgia, indicating acute positive effects of either neural or humoral factors on vascular beds of distant relaxed muscles. Although this beneficial response was observed in both groups, the post-exercise response...

AC relaxation in the iron(8) molecular magnet

Science.gov (United States)

Rose, Geordie

2000-11-01

We investigate the low energy magnetic relaxation characteristics of the ``iron eight'' (Fe8) molecular magnet. Each molecule in this material contains a cluster of eight Fe 3+ ions surrounded by organic ligands. The molecules arrange themselves into a regular lattice with triclinic symmetry. At sufficiently low energies, the electronic spins of the Fe3+ ions lock together into a ``quantum rotator'' with spin S = 10. We derive a low energy effective Hamiltonian for this system, valid for temperatures less than Tc ~ 360 mK , where Tc is the temperature at which the Fe8 system crosses over into a ``quantum regime'' where relaxation characteristics become temperature independent. We show that in this regime the dominant environmental coupling is to the environmental spin bath in the molecule. We show how to explicitly calculate these couplings, given crystallographic information about the molecule, and do this for Fe8. We use this information to calculate the linewidth, topological decoherence and orthogonality blocking parameters. All of these quantities are shown to exhibit an isotope effect. We demonstrate that orthogonality blocking in Fe8 is significant and suppresses coherent tunneling. We then use our low energy effective Hamiltonian to calculate the single-molecule relaxation rate in the presence of an external magnetic field with both AC and DC components by solving the Landau-Zener problem in the presence of a nuclear spin bath. Both sawtooth and sinusoidal AC fields are analyzed. This single-molecule relaxation rate is then used as input into a master equation in order to take into account the many-molecule nature of the full system. Our results are then compared to quantum regime relaxation experiments performed on the Fe8 system.

Fatigue life estimation of welded components considering welding residual stress relaxation and its mean stress effect

International Nuclear Information System (INIS)

Han, Seung Ho; Han, Jeong Woo; Shin, Byung Chun; Kim, Jae Hoon

2003-01-01

The fatigue life of welded joints is sensitive to welding residual stress and complexity of their geometric shapes. To predict the fatigue life more reasonably, the effects of welding residual stress and its relaxation on their fatigue strengths should be considered quantitatively, which are often regarded to be equivalent to the effects of mean stresses by external loads. The hot-spot stress concept should be also adopted which can reduce the dependence of fatigue strengths for various welding details. Considering the factors mentioned above, a fatigue life prediction model using the modified Goodman's diagram was proposed. In this model, an equivalent stress was introduced which is composed of the mean stress based on the hot-spot stress concept and the relaxed welding residual stress. From the verification of the proposed model to real welding details, it is proved that this model can be applied to predict reasonably their fatigue lives

Mass transfer effect of the stalk contraction-relaxation cycle of Vorticella convallaria

Science.gov (United States)

Zhou, Jiazhong; Admiraal, David; Ryu, Sangjin

2014-11-01

Vorticella convallaria is a genus of protozoa living in freshwater. Its stalk contracts and coil pulling the cell body towards the substrate at a remarkable speed, and then relaxes to its extended state much more slowly than the contraction. However, the reason for Vorticella's stalk contraction is still unknown. It is presumed that water flow induced by the stalk contraction-relaxation cycle may augment mass transfer near the substrate. We investigated this hypothesis using an experimental model with particle tracking velocimetry and a computational fluid dynamics model. In both approaches, Vorticella was modeled as a solid sphere translating perpendicular to a solid surface in water. After having been validated by the experimental model and verified by grid convergence index test, the computational model simulated water flow during the cycle based on the measured time course of stalk length changes of Vorticella. Based on the simulated flow field, we calculated trajectories of particles near the model Vorticella, and then evaluated the mass transfer effect of Vorticella's stalk contraction based on the particles' motion. We acknowlege support from Laymann Seed Grant of the University of Nebraska-Lincoln.

Thermally-induced electronic relaxation in structurally-modified Cu{sub 0.1}Ni{sub 0.8}Co{sub 0.2}Mn{sub 1.9}O{sub 4} spinel ceramics

Energy Technology Data Exchange (ETDEWEB)

Shpotyuk, O., E-mail: shpotyuk@novas.lviv.ua [Institute of Materials, Scientific Research Company “Carat”, 202, Stryjska Street, Lviv 79031 (Ukraine); Institute of Physics, Jan Dlugosz University, 13/15, al. Armii Krajowej, Czestochowa 42200 Poland (Poland); Balitska, V. [Institute of Materials, Scientific Research Company “Carat”, 202, Stryjska Street, Lviv 79031 (Ukraine); Lviv State University of Vital Activity Safety, 35, Kleparivska Street, Lviv 79007 (Ukraine); Brunner, M. [Fachhochschule Köln/University of Applied Sciences, 2, Betzdorfer Strasse, Köln 50679 (Germany); Hadzaman, I. [Institute of Materials, Scientific Research Company “Carat”, 202, Stryjska Street, Lviv 79031 (Ukraine); Drohobych Ivan Franko State Pedagogical University, 24, I. Franko Street, Drohobych 82100 (Ukraine); Klym, H. [Institute of Materials, Scientific Research Company “Carat”, 202, Stryjska Street, Lviv 79031 (Ukraine); Lviv Polytechnic National University, 12, Bandera Street, Lviv 79013 (Ukraine)

2015-02-15

Thermally-induced electronic relaxation in structurally-modified Cu{sub 0.1}Ni{sub 0.8}Co{sub 0.2}Mn{sub 1.9}O{sub 4} spinel ceramics is shown to be adequately described by stretched exponential function on time. This kinetics is defined by microsctructure perfectness of the relaxing media, showing obvious onset to stretched exponential behaviour with non-exponentionality index attaining close to 0.43 values for high-monolith ceramics and smaller ones in fine-grained ceramics. Percolation threshold in relaxation-degradation kinetics is detected for ceramics with 10% of NiO extractions, showing the smallest but most prolonged single-path degradation effect. This finding is treated in terms of Phillips’ axiomatic diffusion-to-trap model, where only one of two relaxation channels (caused by operative short-range forces) occurs to be effective, while additional non-operative channels contribute to electronic relaxation in fine-grained ceramics.

Cross relaxation in nitroxide spin labels

DEFF Research Database (Denmark)

Marsh, Derek

2016-01-01

Cross relaxation, and mI-dependence of the intrinsic electron spin-lattice relaxation rate We, are incorporated explicitly into the rate equations for the electron-spin population differences that govern the saturation behaviour of 14N- and 15N-nitroxide spin labels. Both prove important in spin......-label EPR and ELDOR, particularly for saturation recovery studies. Neither for saturation recovery, nor for CW-saturation EPR and CW-ELDOR, can cross relaxation be described simply by increasing the value of We, the intrinsic spin-lattice relaxation rate. Independence of the saturation recovery rates from...... the hyperfine line pumped or observed follows directly from solution of the rate equations including cross relaxation, even when the intrinsic spin-lattice relaxation rate We is mI-dependent....

Relaxation and kinetics in scalar field theories

International Nuclear Information System (INIS)

Boyanovsky, D.; Lawrie, I.D.; Lee, D.

1996-01-01

A new approach to the dynamics of relaxation and kinetics of thermalization in a scalar field theory is presented that incorporates the relevant time scales through the resummation of hard thermal loops. An alternative derivation of the kinetic equations for the open-quote open-quote quasiparticle close-quote close-quote distribution functions is obtained that allows a clear understanding of the different open-quote open-quote coarse-graining close-quote close-quote approximations usually involved in a kinetic description. This method leads to a systematic perturbative expansion to obtain the kinetic equations including hard thermal loop resummation and to an improvement including renormalization, off-shell effects, and contributions that change chemical equilibrium on short time scales. As a by-product of these methods we establish the equivalence between the relaxation time scale in the linearized equation of motion of the quasiparticles and the thermalization time scale of the quasiparticle distribution function in the open-quote open-quote relaxation time approximation close-quote close-quote including hard thermal loop effects. Hard thermal loop resummation dramatically modifies the scattering rate for long wavelength modes as compared to the usual (semi)classical estimate. Relaxation and kinetics are studied both in the unbroken and broken symmetry phases of the theory. The broken symmetry phase also provides the setting to obtain the contribution to the kinetic equations from processes that involve decay of a heavy scalar into light scalar particles in the medium. copyright 1996 The American Physical Society

Electron-phonon relaxation and excited electron distribution in gallium nitride

Energy Technology Data Exchange (ETDEWEB)

Zhukov, V. P. [Institute of Solid State Chemistry, Urals Branch of the Russian Academy of Sciences, Pervomayskaya st. 91, Yekaterinburg (Russian Federation); Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tyuterev, V. G., E-mail: valtyut00@mail.ru [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State Pedagogical University, Kievskaya st. 60, Tomsk (Russian Federation); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Chulkov, E. V. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Tomsk State University, Lenin st. 36, Tomsk (Russian Federation); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain); Echenique, P. M. [Donostia International Physics Center (DIPC), P. Manuel de Lardizabal 4, 20018 San Sebastian (Spain); Departamento de Fisica de Materiales, Facultad de Ciencias Qumicas, UPV/EHU and Centro de Fisica de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, Apdo. 1072, 20080 San Sebastian (Spain)

2016-08-28

We develop a theory of energy relaxation in semiconductors and insulators highly excited by the long-acting external irradiation. We derive the equation for the non-equilibrium distribution function of excited electrons. The solution for this function breaks up into the sum of two contributions. The low-energy contribution is concentrated in a narrow range near the bottom of the conduction band. It has the typical form of a Fermi distribution with an effective temperature and chemical potential. The effective temperature and chemical potential in this low-energy term are determined by the intensity of carriers' generation, the speed of electron-phonon relaxation, rates of inter-band recombination, and electron capture on the defects. In addition, there is a substantial high-energy correction. This high-energy “tail” largely covers the conduction band. The shape of the high-energy “tail” strongly depends on the rate of electron-phonon relaxation but does not depend on the rates of recombination and trapping. We apply the theory to the calculation of a non-equilibrium distribution of electrons in an irradiated GaN. Probabilities of optical excitations from the valence to conduction band and electron-phonon coupling probabilities in GaN were calculated by the density functional perturbation theory. Our calculation of both parts of distribution function in gallium nitride shows that when the speed of the electron-phonon scattering is comparable with the rate of recombination and trapping then the contribution of the non-Fermi “tail” is comparable with that of the low-energy Fermi-like component. So the high-energy contribution can essentially affect the charge transport in the irradiated and highly doped semiconductors.

Effectiveness of autogenic relaxation training on children and adolescents with behavioral and emotional problems.

Science.gov (United States)

Goldbeck, Lutz; Schmid, Katharina

2003-09-01

To investigate the effectiveness of autogenic relaxation training in a mildly disturbed outpatient population of children and adolescents with mostly internalizing symptoms, and/or some aggressive, impulsive, or attention deficit symptoms. Fifty children and adolescents from southern Germany (mean age 10.2 years; range 6-15 years; mostly intact middle class family background) participated in a group intervention program. Fifteen patients were randomly assigned to a waiting-list control group. Behavior symptoms (Child Behavior Checklist), psychosomatic complaints (Giessen Complaint List), and level of stress were assessed before and after the intervention or after the waiting phase. Individual goal attainment was evaluated at the end of the intervention and in a 3-month follow-up. The parent report on CBCL reflected reduced symptoms compared with control. The child report indicated reduced stress and psychosomatic complaints both in the intervention and control group, and no significant group x time interaction effects occurred on these scales. Effect sizes of 0.49 in the CBCL and 0.36 in the complaint list indicated clinically relevant effects of the intervention compared with the control group. At the end of the intervention, 56% of the children and 55% of the parents reported partial goal attainment, 38% of the children and 30% of the parents reported complete goal attainment; 71% of the parents confirmed partial goal attainment 3 months postintervention. Autogenic relaxation training is an effective broadband method for children and adolescents.

Enhancement effects and relaxivities of gadolinium-DTPA at 1.5 versus 3 tesla. A phantom study

International Nuclear Information System (INIS)

Sasaki, Makoto; Shibata, Eri; Kanbara, Yoshiyuki; Ehara, Shigeru

2005-01-01

The purpose of this study was to investigate the difference in enhancement effects and relaxivities of the gadolinium chelate at 1.5 and 3 Tesla (T) and to elucidate the contribution of the high magnetic field to contrast enhancement in spin-echo (SE) and gradient-echo (GRE) images. Phantoms containing water with or without gadopentetate dimeglumine (Gd-DTPA) at different concentrations were scanned using 1.5T and 3T MRI scanners of the same manufacturer and under the same temperature conditions and scanning parameters. Relaxivities of gadolinium, R 1 and R 2 , were estimated from serial T 1 and T 2 values of the phantoms using linear regression. Contrast enhancement ratios in SE and GRE T 1 -weighted images were compared at 1.5 and 3T. The R 1 and R 2 of Gd-DTPA at 1.5 and 3T were 4.79 and 5.14, and 4.50 and 5.09, respectively. Although the relaxivities at 3T were slightly lower than those at 1.5T, the contrast enhancement ratio improved in both SE and GRE images as a result of T 1 prolongation of the water at 3T. The decrease in relaxivities of the Gd-DTPA at 3T appears to be so small that T 1 prolongation of the water improves contrast enhancement, suggesting a potential clinical advantage in administration of Gd-DTPA at high field strength. (author)

Effect of two yoga-based relaxation techniques on memory scores and state anxiety

Directory of Open Access Journals (Sweden)

Telles Shirley

2009-08-01

Full Text Available Abstract Background A yoga practice involving cycles of yoga postures and supine rest (called cyclic meditation was previously shown to improve performance in attention tasks more than relaxation in the corpse posture (shavasana. This was ascribed to reduced anxiety, though this was not assessed. Methods In fifty-seven male volunteers (group average age ± S.D., 26.6 ± 4.5 years the immediate effect of two yoga relaxation techniques was studied on memory and state anxiety. All participants were assessed before and after (i Cyclic meditation (CM practiced for 22:30 minutes on one day and (ii an equal duration of Supine rest (SR or the corpse posture (shavasana, on another day. Sections of the Wechsler memory scale (WMS were used to assess; (i attention and concentration (digit span forward and backward, and (ii associate learning. State anxiety was assessed using Spielberger's State-Trait Anxiety Inventory (STAI. Results There was a significant improvement in the scores of all sections of the WMS studied after both CM and SR, but, the magnitude of change was more after CM compared to after SR. The state anxiety scores decreased after both CM and SR, with a greater magnitude of decrease after CM. There was no correlation between percentage change in memory scores and state anxiety for either session. Conclusion A cyclical combination of yoga postures and supine rest in CM improved memory scores immediately after the practice and decreased state anxiety more than rest in a classical yoga relaxation posture (shavasana.

Hearth and Campfire Influences on Arterial Blood Pressure: Defraying the Costs of the Social Brain through Fireside Relaxation

Directory of Open Access Journals (Sweden)

Christopher Dana Lynn

2014-04-01

Full Text Available The importance of fire in human evolutionary history is widely acknowledged but the extent not fully explored. Fires involve flickering light, crackling sounds, warmth, and a distinctive smell. For early humans, fire likely extended the day, provided heat, helped with hunting, warded off predators and insects, illuminated dark places, and facilitated cooking. Campfires also may have provided social nexus and relaxation effects that could have enhanced prosocial behavior. According to this hypothesis, calmer, more tolerant people would have benefited in the social milieu via fireside interactions relative to individuals less susceptible to relaxation response. Using a randomized crossover design that disaggregated fire's sensory properties, pre-posttest blood pressure measures were compared among 226 adults across three studies with respect to viewing simulated muted-fire, fire-with-sound, and control conditions, in addition to tests for interactions with hypnotizability, absorption, and prosociality. Results indicated consistent blood pressure decreases in the fire-with-sound condition, particularly with a longer duration of stimulus, and enhancing effects of absorption and prosociality. Findings confirm that hearth and campfires induce relaxation as part of a multisensory, absorptive, and social experience. Enhancements to relaxation capacities in the human social brain likely took place via feedback involving these and other variables.

Hearth and campfire influences on arterial blood pressure: defraying the costs of the social brain through fireside relaxation.

Science.gov (United States)

Lynn, Christopher Dana

2014-11-11

The importance of fire in human evolutionary history is widely acknowledged but the extent not fully explored. Fires involve flickering light, crackling sounds, warmth, and a distinctive smell. For early humans, fire likely extended the day, provided heat, helped with hunting, warded off predators and insects, illuminated dark places, and facilitated cooking. Campfires also may have provided social nexus and relaxation effects that could have enhanced prosocial behavior. According to this hypothesis, calmer, more tolerant people would have benefited in the social milieu via fireside interactions relative to individuals less susceptible to relaxation response. Using a randomized crossover design that disaggregated fire's sensory properties, pre-posttest blood pressure measures were compared among 226 adults across three studies with respect to viewing simulated muted-fire, fire-with-sound, and control conditions, in addition to tests for interactions with hypnotizability, absorption, and prosociality. Results indicated consistent blood pressure decreases in the fire-with-sound condition, particularly with a longer duration of stimulus, and enhancing effects of absorption and prosociality. Findings confirm that hearth and campfires induce relaxation as part of a multisensory, absorptive, and social experience. Enhancements to relaxation capacities in the human social brain likely took place via feedback involving these and other variables.

Functional behavior of the anomalous magnetic relaxation observed in melt-textured YBa{sub 2}Cu{sub 3}O{sub 7-δ} samples showing the paramagnetic Meissner effect

Energy Technology Data Exchange (ETDEWEB)

Dias, F.T., E-mail: fabio.dias@ufpel.edu.br [Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900, Pelotas, Rio Grande do Sul (Brazil); Vieira, V.N.; Garcia, E.L. [Instituto de Física e Matemática, Universidade Federal de Pelotas, Caixa Postal 354, 96010-900, Pelotas, Rio Grande do Sul (Brazil); Wolff-Fabris, F.; Kampert, E. [Dresden High Magnetic Field Laboratory, Helmholtz-Zentrum Dresden-Rossendorf, 01314, Dresden (Germany); Gouvêa, C.P. [National Institute of Metrology, Quality and Technology (Inmetro), Material Metrology Division, 25250-020, Duque de Caxias, Rio de Janeiro (Brazil); Schaf, J. [Instituto de Física, Universidade Federal do Rio Grande do Sul, 91501-970, Porto Alegre, Rio Grande do Sul (Brazil); Obradors, X.; Puig, T. [Institut de Ciència de Materials de Barcelona, CSIC, Universitat Autònoma de Barcelona, 08193, Bellaterra (Spain); Roa, J.J. [Departamento de Ciencia de Materiales e Ingeniería Metalúrgica, Universitat Politècnica de Catalunya, 08028, Barcelona (Spain)

2016-10-15

Highlights: • Paramagnetic Meissner effect observed up to 5T in FCC and FCW measurements. • Time effects evidenced by irreversibilities between FCC and FCW measurements. • Strong time effects causing an anomalous paramagnetic relaxation. • Paramagnetic relaxation governed by different flux dynamics in different intervals. • An interpretative analysis to identify the flux dynamics in the relaxation process. - Abstract: We have studied the functional behavior of the field-cooled (FC) magnetic relaxation observed in melt-textured YBa{sub 2}Cu{sub 3}O{sub 7-δ} (Y123) samples with 30 wt% of Y{sub 2}Ba{sub 1}Cu{sub 1}O{sub 5} (Y211) phase, in order to investigate anomalous paramagnetic moments observed during the experiments. FC magnetic relaxation experiments were performed under controlled conditions, such as cooling rate and temperature. Magnetic fields up to 5T were applied parallel to the ab plane and along the c-axis. Our results are associated with the paramagnetic Meissner effect (PME), characterized by positive moments during FC experiments, and related to the magnetic flux compression into the samples. After different attempts our experimental data could be adequately fitted by an exponential decay function with different relaxation times. We discuss our results suggesting the existence of different and preferential flux dynamics governing the anomalous FC paramagnetic relaxation in different time intervals. This work is one of the first attempts to interpret this controversial effect in a simple analysis of the pinning mechanisms and flux dynamics acting during the time evolution of the magnetic moment. However, the results may be useful to develop models to explain this interesting and still misunderstood feature of the paramagnetic Meissner effect.

Stability investigations of relaxing molecular gas flows. Results and perspectives

Science.gov (United States)

Grigor'ev, Yurii N.; Ershov, Igor V.

2017-10-01

This article presents results of systematic investigations of a dissipative effect which manifests itself as the growth of hydrodynamic stability and suppression of turbulence in relaxing molecular gas flows. The effect can be a new way for control stability and laminar turbulent transition in aerodynamic flows. The consideration of suppression of inviscid acoustic waves in 2D shear flows is presented. Nonlinear evolution of large-scale vortices and Kelvin — Helmholtz waves in relaxing shear flows are studied. Critical Reynolds numbers in supersonic Couette flows are calculated analytically and numerically within the framework of both classical linear and nonlinear energy hydrodynamic stability theories. The calculations clearly show that the relaxation process can appreciably delay the laminar-turbulent transition. The aim of this article is to show the new dissipative effect, which can be used for flow control and laminarization.

Limiting conditions for operation relaxation program

International Nuclear Information System (INIS)

Merz, J.F.

1985-01-01

The purpose of this effort was to assess the impact of system maintenance unavailability on plant risk to provide technical justification for the relaxation of system limiting conditions for operation from three to seven days. The primary goal of the relaxation program is to allow for more thorough equipment maintenance. A potential increase in out-of-service time for a particular outage caused by the performance of more effective repairs will be counterbalanced by a probable decrease in the frequency in the outage rate of a component. Benefits resulting from an increase in allowed outage time include: (a) a potential reduction in total system out-of-service time, (b) a minimization of challenges to plant systems, and (c) a reduction in the number of emergency technical specification change requests. This program therefore offers an opportunity to more effectively manage plant maintenance and operation

Fetal response to abbreviated relaxation techniques. A randomized controlled study.

Science.gov (United States)

Fink, Nadine S; Urech, Corinne; Isabel, Fornaro; Meyer, Andrea; Hoesli, Irène; Bitzer, Johannes; Alder, Judith

2011-02-01

stress during pregnancy can have adverse effects on the course of pregnancy and on fetal development. There are few studies investigating the outcome of stress reduction interventions on maternal well-being and obstetric outcome. this study aims (1) to obtain fetal behavioral states (quiet/active sleep, quiet/active wakefulness), (2) to investigate the effects of maternal relaxation on fetal behavior as well as on uterine activity, and (3) to investigate maternal physiological and endocrine parameters as potential underlying mechanisms for maternal-fetal relaxation-transferral. the behavior of 33 fetuses was analyzed during laboratory relaxation/quiet rest (control group, CG) and controlled for baseline fetal behavior. Potential associations between relaxation/quiet rest and fetal behavior (fetal heart rate (FHR), FHR variation, FHR acceleration, and body movements) and uterine activity were studied, using a computerized cardiotocogram (CTG) system. Maternal heart rate, blood pressure, cortisol, and norepinephrine were measured. intervention (progressive muscle relaxation, PMR, and guided imagery, GI) showed changes in fetal behavior. The intervention groups had higher long-term variation during and after relaxation compared to the CG (p=.039). CG fetuses had more FHR acceleration, especially during and after quiet rest (p=.027). Women in the PMR group had significantly more uterine activity than women in the GI group (p=.011) and than CG women. Maternal heart rate, blood pressure, and stress hormones were not associated with fetal behavior. this study indicates that the fetus might participate in maternal relaxation and suggests that GI is superior to PMR. This could especially be true for women who tend to direct their attention to body sensations such as abdominal activity. 2010 Elsevier Ltd. All rights reserved.

Relaxation System

Science.gov (United States)

1987-01-01

Environ Corporation's relaxation system is built around a body lounge, a kind of super easy chair that incorporates sensory devices. Computer controlled enclosure provides filtered ionized air to create a feeling of invigoration, enhanced by mood changing aromas. Occupant is also surrounded by multidimensional audio and the lighting is programmed to change colors, patterns, and intensity periodically. These and other sensory stimulators are designed to provide an environment in which the learning process is stimulated, because research has proven that while an individual is in a deep state of relaxation, the mind is more receptive to new information.

Generalized Lenard-Balescu calculations of electron-ion temperature relaxation in beryllium plasma.

Science.gov (United States)

Fu, Zhen-Guo; Wang, Zhigang; Li, Da-Fang; Kang, Wei; Zhang, Ping

2015-09-01

The problem of electron-ion temperature relaxation in beryllium plasma at various densities (0.185-18.5g/cm^{3}) and temperatures [(1.0-8)×10^{3} eV] is investigated by using the generalized Lenard-Balescu theory. We consider the correlation effects between electrons and ions via classical and quantum static local field corrections. The numerical results show that the electron-ion pair distribution function at the origin approaches the maximum when the electron-electron coupling parameter equals unity. The classical result of the Coulomb logarithm is in agreement with the quantum result in both the weak (Γ_{ee}1) electron-electron coupling ranges, whereas it deviates from the quantum result at intermediate values of the coupling parameter (10^{-2}Coulomb logarithm will decrease and the corresponding relaxation rate ν_{ie} will increase. In addition, a simple fitting law ν_{ie}/ν_{ie}^{(0)}=a(ρ_{Be}/ρ_{0})^{b} is determined, where ν_{ie}^{(0)} is the relaxation rate corresponding to the normal metal density of Be and ρ_{0}, a, and b are the fitting parameters related to the temperature and the degree of ionization 〈Z〉 of the system. Our results are expected to be useful for future inertial confinement fusion experiments involving Be plasma.

Active nematic gels as active relaxing solids

Science.gov (United States)

Turzi, Stefano S.

2017-11-01

I propose a continuum theory for active nematic gels, defined as fluids or suspensions of orientable rodlike objects endowed with active dynamics, that is based on symmetry arguments and compatibility with thermodynamics. The starting point is our recent theory that models (passive) nematic liquid crystals as relaxing nematic elastomers. The interplay between viscoelastic response and active dynamics of the microscopic constituents is naturally taken into account. By contrast with standard theories, activity is not introduced as an additional term of the stress tensor, but it is added as an external remodeling force that competes with the passive relaxation dynamics and drags the system out of equilibrium. In a simple one-dimensional channel geometry, we show that the interaction between nonuniform nematic order and activity results in either a spontaneous flow of particles or a self-organization into subchannels flowing in opposite directions.

Cross-relaxation solid state lasers

International Nuclear Information System (INIS)

Antipenko, B.M.

1989-01-01

Cross-relaxation functional diagrams provide a high quantum efficiency for pumping bands of solid state laser media and a low waste heat. A large number of the cross-relaxation mechanisms for decay rare earth excited states in crystals have been investigated. These investigations have been a starting-point for development of the cross-relaxation solid state lasers. For example, the cross-relaxation interactions, have been used for the laser action development of LiYF 4 :Gd-Tb. These interactions are important elements of the functional diagrams of the 2 μm Ho-doped media sensitized with Er and Tm and the 3 μm Er-doped media. Recently, new efficient 2 μm laser media with cross-relaxation pumping diagrams have been developed. Physical aspects of these media are the subject of this paper. A new concept of the Er-doped medium, sensitized with Yb, is illustrated

Electron-mediated relaxation following ultrafast pumping of strongly correlated materials: model evidence of a correlation-tuned crossover between thermal and nonthermal states.

Science.gov (United States)

Moritz, B; Kemper, A F; Sentef, M; Devereaux, T P; Freericks, J K

2013-08-16

We examine electron-electron mediated relaxation following ultrafast electric field pump excitation of the fermionic degrees of freedom in the Falicov-Kimball model for correlated electrons. The results reveal a dichotomy in the temporal evolution of the system as one tunes through the Mott metal-to-insulator transition: in the metallic regime relaxation can be characterized by evolution toward a steady state well described by Fermi-Dirac statistics with an increased effective temperature; however, in the insulating regime this quasithermal paradigm breaks down with relaxation toward a nonthermal state with a complicated electronic distribution as a function of momentum. We characterize the behavior by studying changes in the energy, photoemission response, and electronic distribution as functions of time. This relaxation may be observable qualitatively on short enough time scales that the electrons behave like an isolated system not in contact with additional degrees of freedom which would act as a thermal bath, especially when using strong driving fields and studying materials whose physics may manifest the effects of correlations.

Hydrogels with tunable stress relaxation regulate stem cell fate and activity

Science.gov (United States)

Chaudhuri, Ovijit; Gu, Luo; Klumpers, Darinka; Darnell, Max; Bencherif, Sidi A.; Weaver, James C.; Huebsch, Nathaniel; Lee, Hong-Pyo; Lippens, Evi; Duda, Georg N.; Mooney, David J.

2016-03-01

Natural extracellular matrices (ECMs) are viscoelastic and exhibit stress relaxation. However, hydrogels used as synthetic ECMs for three-dimensional (3D) culture are typically elastic. Here, we report a materials approach to tune the rate of stress relaxation of hydrogels for 3D culture, independently of the hydrogel's initial elastic modulus, degradation, and cell-adhesion-ligand density. We find that cell spreading, proliferation, and osteogenic differentiation of mesenchymal stem cells (MSCs) are all enhanced in cells cultured in gels with faster relaxation. Strikingly, MSCs form a mineralized, collagen-1-rich matrix similar to bone in rapidly relaxing hydrogels with an initial elastic modulus of 17 kPa. We also show that the effects of stress relaxation are mediated by adhesion-ligand binding, actomyosin contractility and mechanical clustering of adhesion ligands. Our findings highlight stress relaxation as a key characteristic of cell-ECM interactions and as an important design parameter of biomaterials for cell culture.

Profile relaxation and tilt instability in a field-reversed configuration

International Nuclear Information System (INIS)

Ohtani, H.; Horiuchi, R.; Sato, T.

2003-01-01

The profile relaxation from a magnetic hydrodynamic (MHD) profile to a kinetic equilibrium in field-reversed configurations (FRCs) is investigated by two-dimensional electromagnetic particle simulation. The radial oscillation takes place in order to relax an excess energy in the MHD profile, and the system spontaneously relaxes toward a kinetic equilibrium. In this kinetic equilibrium, the hollow electron current profile is realized as a result of the combined effects of the single particle orbits and the ion finite Larmor radius, and the ion current profile becomes peaked due to the effect of the ion meandering motion. Three-dimensional full electromagnetic particle simulation is also performed to study the stability of these kinetic equilibrium against the tilt mode. The growth rate of the tilt instability is reduced by the kinetic effects. It is found that the stabilization effect of tilt mode becomes much distinct when the current density changes from the peaked profile to the hollow one. (author)

Profile relaxation and tilt instability in a field-reversed configuration

International Nuclear Information System (INIS)

Ohtani, H.; Horiuchi, R.; Sato, T.

2002-10-01

The profile relaxation from a magnetohydrodynamic (MHD) profile to a kinetic equilibrium in field-reversed configurations (FRCs) is investigated by two-dimensional electromagnetic particle simulation. The radial oscillation takes place in order to relax an excess energy in the MHD profile, and the system spontaneously relaxes toward a kinetic equilibrium. In this kinetic equilibrium, the hollow electron current profile is realized as a result of the combined effects of the single particle orbits and the ion finite Larmor radius, and the ion current profile becomes peaked due to the effect of the ion meandering motion. Three-dimensional full electromagnetic particle simulation is also performed to study the stability of these kinetic equilibrium against the tilt mode. The growth rate of the tilt instability is reduced by the kinetic effects. It is found that the stabilization effect of tilt mode becomes much distinct when the current density changes from the peaked profile to the hollow one. (author)

Profile relaxation and tilt instability in a field-reversed configuration

International Nuclear Information System (INIS)

Ohtani, H.; Horiuchi, R.; Sato, T.

2002-01-01

The profile relaxation from a magnetichydrodynamic (MHD) profile to a kinetic equilibrium in field-reversed configurations (FRCs) in investigated by two-dimensional electromagnetic particle simulation. The radial oscillation takes place in order to relax an excess energy in the MHD profile, and the system spontaneously relaxes toward a kinetic equilibrium. In this kinetic equilibrium, the hollow electron current profile is realized as a result of the combined effects of the single particle orbits and the ion finite Larmor radius, and the ion current profile becomes peaked due to the effect of the ion meandering motion. Three-dimensional full electromagnetic particle simulations is also performed to study the stability of these kinetic equilibrium against the tilt mode. The growth rate of the tilt instability is reduced by the kinetic is effects. It is found that the stabilization effect of tilt mode becomes much distinct when the current density changes from the peaked profile to the hollow one. (author)

Dielectric relaxation study of the dynamics of monosaccharides: D-ribose and 2-deoxy-D-ribose

Energy Technology Data Exchange (ETDEWEB)

Kaminski, K; Kaminska, E; Wlodarczyk, P; Paluch, M; Ziolo, J [Institute of Physics, Silesian University, ulica Uniwersytecka 4, 40-007 Katowice (Poland); Ngai, K L [Naval Research Laboratory, Washington, DC 20375-5320 (United States)

2008-08-20

The dielectric loss spectra of two closely related monosaccharides, D-ribose and 2-deoxy-D-ribose, measured at ambient and elevated pressures are presented. 2-deoxy-D-ribose and D-ribose are respectively the building blocks of the backbone chains in the nucleic acids DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Small differences in the structure between D-ribose and 2-deoxy-D-ribose result in changes of the glass transition temperature T{sub g}, as well as the dielectric strength and activation enthalpy of the secondary relaxations. However, the frequency dispersion of the structural {alpha}-relaxation for the same relaxation time remains practically the same. Two secondary relaxations are present in both sugars. The slower secondary relaxation shifts to lower frequencies with increasing applied pressure, but not the faster one. This pressure dependence indicates that the slower secondary relaxation is the important and 'universal' Johari-Goldstein {beta}-relaxation of both sugars according to one of the criteria set up to classify secondary relaxations. Additional confirmation of this conclusion comes from good agreement of the observed relaxation time of the slower secondary relaxation with the primitive relaxation time calculated from the coupling model. All the dynamic properties of D-ribose and 2-deoxy-D-ribose are similar to the other monosaccharides, glucose, fructose, galactose and sorbose, except for the much larger relaxation strength of the {alpha}-relaxation of the former compared to the latter. The difference may distinguish the chemical and biological functions of D-ribose and 2-deoxy-D-ribose from the other monosaccharides.

The relaxation time approximation

International Nuclear Information System (INIS)

Gairola, R.P.; Indu, B.D.

1991-01-01

A plausible approximation has been made to estimate the relaxation time from a knowledge of the transition probability of phonons from one state (r vector, q vector) to other state (r' vector, q' vector), as a result of collision. The relaxation time, thus obtained, shows a strong dependence on temperature and weak dependence on the wave vector. In view of this dependence, relaxation time has been expressed in terms of a temperature Taylor's series in the first Brillouin zone. Consequently, a simple model for estimating the thermal conductivity is suggested. the calculations become much easier than the Callaway model. (author). 14 refs

NMR water-proton spin-lattice relaxation time of human red blood cells and red blood cell suspensions

International Nuclear Information System (INIS)

Sullivan, S.G.; Rosenthal, J.S.; Winston, A.; Stern, A.

1988-01-01

NMR water-proton spin-lattice relaxation times were studied as probes of water structure in human red blood cells and red blood cell suspensions. Normal saline had a relaxation time of about 3000 ms while packed red blood cells had a relaxation time of about 500 ms. The relaxation time of a red blood cell suspension at 50% hematocrit was about 750 ms showing that surface charges and polar groups of the red cell membrane effectively structure extracellular water. Incubation of red cells in hypotonic saline increases relaxation time whereas hypertonic saline decreases relaxation time. Relaxation times varied independently of mean corpuscular volume and mean corpuscular hemoglobin concentration in a sample population. Studies with lysates and resealed membrane ghosts show that hemoglobin is very effective in lowering water-proton relaxation time whereas resealed membrane ghosts in the absence of hemoglobin are less effective than intact red cells. 9 refs.; 3 figs.; 1 table

Real-Time Observation of Ultrafast Intraband Relaxation and Exciton Multiplication in PbS Quantum Dots

KAUST Repository

El-Ballouli, Ala’a O.

2014-03-19

We examine ultrafast intraconduction band relaxation and multiple-exciton generation (MEG) in PbS quantum dots (QDs) using transient absorption spectroscopy with 120 fs temporal resolution. The intraconduction band relaxation can be directly and excellently resolved spectrally and temporally by applying broadband pump-probe spectroscopy to excite and detect the wavelengths around the exciton absorption peak, which is located in the near-infrared region. The time-resolved data unambiguously demonstrate that the intraband relaxation time progressively increases as the pump-photon energy increases. Moreover, the relaxation time becomes much shorter as the size of the QDs decreases, indicating the crucial role of spatial confinement in the intraband relaxation process. Additionally, our results reveal the systematic scaling of the intraband relaxation time with both excess energy above the effective energy band gap and QD size. We also assess MEG in different sizes of the QDs. Under the condition of high-energy photon excitation, which is well above the MEG energy threshold, ultrafast bleach recovery due to the nonradiative Auger recombination of the multiple electron-hole pairs provides conclusive experimental evidence for the presence of MEG. For instance, we achieved quantum efficiencies of 159, 129 and 106% per single-absorbed photon at pump photoexcition of three times the band gap for QDs with band gaps of 880 nm (1.41 eV), 1000 nm (1.24 eV) and 1210 nm (1.0 eV), respectively. These findings demonstrate clearly that the efficiency of transferring excess photon energy to carrier multiplication is significantly increased in smaller QDs compared with larger ones. Finally, we discuss the Auger recombination dynamics of the multiple electron-hole pairs as a function of QD size.

Analysis of vibroprotection characteristics of pneumatic relaxation seat suspension with capability of vibration energy recuperation

Directory of Open Access Journals (Sweden)

Lyashenko Mikhail

2017-01-01

Full Text Available This paper proposes mechanism and control algorithm for pneumatic relaxation system of suspension with vibration energy recuperation applied to standard vehicle operator seat (“Sibeko” company. Mathematical model of the seat pneumatic relaxation suspension with two additional air volumes was created. Pneumatic motor – recuperator activated by means of air flow from the one additional volume to another is installed in air piping between additional volumes. Computational research was made in Matlab/Simulink. Amplitude-frequency characteristics of transmission coefficient for standard and proposed suspensions were plotted for preliminary evaluation of vibration protection properties of seat suspension. Performed comparative analysis of amplitude-frequency characteristics shows that noticeable improvement of vibration protection properties of pneumatic relaxation suspension system with vibration energy recuperation in comparison with standard system both in region of resonance disturbances and in above-resonance region. Main ways for further improvement of vibration protection properties of proposed system were marked out.

Stress relaxation of bi-disperse polystyrene melts

DEFF Research Database (Denmark)

Hengeller, Ludovica; Huang, Qian; Dorokhin, Andriy

2016-01-01

We present start-up of uniaxial extension followed by stress relaxation experiments of a bi-disperse 50 % by weight blend of 95k and 545k molecular weight polystyrene. We also show, for comparison, stress relaxation measurements of the polystyrene melts with molecular weight 95k and 545k, which...... are the components of the bi-disperse melt. The measurements show three separated relaxation regimes: a fast regime, a transition regime, and a slow regime. In the fast regime, the orientation of the long chains is frozen and the stress relaxation is due to stretch relaxation of the short chains primarily....... Conversely in the slow regime, the long chains have retracted and undergo relaxation of orientation in fully relaxed short chains....

Effect of alkali ion on relaxation properties of binary alkali-borate glasses

International Nuclear Information System (INIS)

Lomovskoj, V.A.; Bartenev, G.M.

1992-01-01

Method of relaxation spectrometry were used to analyze the data on internal friction spectra of lithium, sodium, potassium and rubidium alkali-borate glasses in wide range of temperatures and frequencies. The nature of two relaxation processes was clarified: β m -process, related with mobility of alkaline metal cations, and α-process (vitrification), conditioned by system transformation from viscous-flow to vitreous state. It is shown that atomic-molecular mechanism of vitrification process changes when passing from vitreous B 2 O 3 to alkali-borate glasses

Myofilament calcium sensitivity: Role in regulation of in vivo cardiac contraction and relaxation

Directory of Open Access Journals (Sweden)

Jae-Hoon Chung

2016-12-01

Full Text Available Myofilament calcium sensitivity is an often-used indicator of cardiac muscle function, often assessed in disease states such as hypertrophic cardiomyopathy (HCM and dilated cardiomyopathy (DCM. While calcium sensitivity measurement provides important insights into the mechanical force-generating capability of a muscle at steady-state, the dynamic behavior of the muscle cannot be sufficiently assessed with a force-pCa curve alone. The dissociation constant (Kd of the force-pCa curve depends on the ratio of the apparent on-rate (kon and apparent off-rate (koff of calcium on TnC and as a stand-alone parameter cannot provide an accurate depiction of the dynamic contraction and relaxation behavior without the additional quantification of kon or koff, or actually measuring dynamic twitch kinetics in an intact muscle. In this review, we examine the effect of length, frequency, and beta-adrenergic stimulation on myofilament calcium sensitivity and dynamic contraction, the effect of membrane permeabilization on calcium sensitivity, and the dynamic consequences of various myofilament protein mutations with potential implications in contractile and relaxation behavior.

BREATHING EXERCISE RELAXATION INCREASE PHSYCOLOGICAL RESPONSE PRESCHOOL CHILDREN

Directory of Open Access Journals (Sweden)

Yuni Sufyanti Arief

2017-07-01

Full Text Available Introduction: Being hospitalize will be made the children become stress. Hospitalization response of the child particularly is afraid sense regard to painfull procedure and increase to attack the invasive procedure. The aimed of this study was to describe the influence of breathing exercise relaxation technique regarded to phsycological receiving responses in the preeliminary school chidren while they were receiving invasive procedure. Method: A quasy experimental purposive sampling design was used in this study. There were 20 respondents who met to the inclusion criteria. The independent variable was the breathing exercise relaxation technique and the dependent variable was phsycological receiving responses. Data for phsylogical response were collected by using observation form then analyzed by using Wilcoxon Signed Rank Test and Mann Whitney U Test with significance level α≤0.05. Result :  The result showed that breathing exercise relaxation technique had significance influence to phsycological response (p=0.000. Discussion: It,s can be concluded that breathing exercise relaxation technique has an effect to increase pshycological response in preeliminary school children who received invasive procedure.

Predicting the effectiveness of virtual reality relaxation on pain and anxiety when added to PCA morphine in patients having burns dressings changes.

Science.gov (United States)

Konstantatos, A H; Angliss, M; Costello, V; Cleland, H; Stafrace, S

2009-06-01

Pain arising in burns sufferers is often severe and protracted. The prospect of a dressing change can heighten existing pain by impacting both physically and psychologically. In this trial we examined whether pre-procedural virtual reality guided relaxation added to patient controlled analgesia with morphine reduced pain severity during awake dressings changes in burns patients. We conducted a prospective randomized clinical trial in all patients with burns necessitating admission to a tertiary burns referral centre. Eligible patients requiring awake dressings changes were randomly allocated to single use virtual reality relaxation plus intravenous morphine patient controlled analgesia (PCA) infusion or to intravenous morphine patient controlled analgesia infusion alone. Patients rated their worst pain intensity during the dressing change using a visual analogue scale. The primary outcome measure was presence of 30% or greater difference in pain intensity ratings between the groups in estimation of worst pain during the dressing change. Of 88 eligible and consenting patients having awake dressings changes, 43 were assigned to virtual reality relaxation plus intravenous morphine PCA infusion and 43 to morphine PCA infusion alone. The group receiving virtual reality relaxation plus morphine PCA infusion reported significantly higher pain intensities during the dressing change (mean=7.3) compared with patients receiving morphine PCA alone (mean=5.3) (p=0.003) (95% CI 0.6-2.8). The addition of virtual reality guided relaxation to morphine PCA infusion in burns patients resulted in a significant increase in pain experienced during awake dressings changes. In the absence of a validated predictor for responsiveness to virtual reality relaxation such a therapy cannot be recommended for general use in burns patients having awake dressings changes.

Effect of static mixer on the performance of compact plate heat exchanger with zwitterionic type of drag-reducing additives

Energy Technology Data Exchange (ETDEWEB)

Blais, C.; Wollerstrand, J.

1997-06-01

The main task of the project was to investigate the influence of drag-reducing additives (DRA) dissolved in circulating hot water on heat transfer in compact plate heat exchangers (PHE). Furthermore the result of flow disturbance (static mixing) immediately before the PHE on pressure drop and heat transfer was clarified. The project used a new type of DRA (surfactants of zwitterionic type) for two different temperature ranges. A dedicated test rig, `Ansgar`, was built for the purpose. Good thermal and mechanical stability also outside the operating range was observed except some sensitivity for water hardness at high temperatures for DRA2. Similarly to known investigations, the heat transfer coefficient was significantly reduced by DRA in heat exchangers. In PHE used however, the heat transfer reduction was considerably lower in the high flow region. A static mixer placed in front of the PHE was found to significantly improve heat transfer, especially at high flow rates. On the other hand, an additional pressure drop was introduced. Therefore the optimal choice of static mixer needs further investigation. Specially designed PHE combining mixing and heat transfer functions could be beneficial to reducing the effects of additives in thermal systems. The relaxation time (RT) of drag-reducing additives in water solutions flowing through test pipes with known geometries was estimated by monitoring specific pressure drop variation along the pipe. These preliminary experiments in respect to relaxation time showed that RT depends on the flow rate and on the temperature 12 refs, 11 figs, 1 tab

Plasmon-mediated energy relaxation in graphene

Energy Technology Data Exchange (ETDEWEB)

Ferry, D. K. [School of Electrical, Computer, and Energy Engineering, Arizona State University, Tempe, Arizona 85287-5706 (United States); Somphonsane, R. [Department of Physics, King Mongkut' s Institute of Technology, Ladkrabang, Bangkok 10520 (Thailand); Ramamoorthy, H.; Bird, J. P. [Department of Electrical Engineering, University at Buffalo, the State University of New York, Buffalo, New York 14260-1500 (United States)

2015-12-28

Energy relaxation of hot carriers in graphene is studied at low temperatures, where the loss rate may differ significantly from that predicted for electron-phonon interactions. We show here that plasmons, important in the relaxation of energetic carriers in bulk semiconductors, can also provide a pathway for energy relaxation in transport experiments in graphene. We obtain a total loss rate to plasmons that results in energy relaxation times whose dependence on temperature and density closely matches that found experimentally.

Rock Tea extract (Jasonia glutinosa) relaxes rat aortic smooth muscle by inhibition of L-type Ca(2+) channels.

Science.gov (United States)

Valero, Marta Sofía; Oliván-Viguera, Aida; Garrido, Irene; Langa, Elisa; Berzosa, César; López, Víctor; Gómez-Rincón, Carlota; Murillo, María Divina; Köhler, Ralf

2015-12-01

In traditional herbal medicine, Rock Tea (Jasonia glutinosa) is known for its prophylactic and therapeutic value in various disorders including arterial hypertension. However, the mechanism by which Rock Tea exerts blood pressure-lowering actions has not been elucidated yet. Our aim was to demonstrate vasorelaxing effects of Rock Tea extract and to reveal its possible action mechanism. Isometric myography was conducted on high-K+-precontracted rings from rat thoracic aorta and tested extracts at concentrations of 0.5-5 mg/ml. Whole-cell patch-clamp experiments were performed in rat aortic vascular smooth muscle cells (line A7r5) to determine blocking effects on L-type Ca(2+) channels. Rock Tea extract relaxed the aorta contracted by high [K+] concentration dependently with an EC50 of ≈2.4 mg/ml and produced ≈75 % relaxation at the highest concentration tested. The L-type Ca(2+) channel blocker, verapamil (10(-6) M), had similar effects. Rock Tea extract had no effect in nominally Ca(2+)-free high-K(+) buffer but significantly inhibited contractions to re-addition of Ca(2+). Rock Tea extract inhibited the contractions induced by the L-type Ca(2+) channel activator Bay K 8644 (10(-5) M) and by phenylephrine (10(-6) M). Rock Tea extract and Y-27632 (10(-6) M), Rho-kinase inhibitor, had similar effects and the respective effects were not additive. Patch-clamp experiments demonstrated that Rock Tea extract (2.5 mg/ml) virtually abolished L-type Ca(2+) currents in A7r5. We conclude that Rock Tea extract produced vasorelaxation of rat aorta and that this relaxant effect is mediated by inhibition of L-type Ca(2+) channels. Rock Tea extracts may be of phytomedicinal value for prevention and adjuvant treatment of hypertension and other cardiovascular diseases.

Water properties and structure of pork sausages as affected by high-pressure processing and addition of carrot fibre

DEFF Research Database (Denmark)

Møller, Sandie Mejer; Grossi, Alberto Blak; Christensen, Mette

2011-01-01

The effects of high-pressure processing (HPP) and addition of carrot fibre on pork sausages have been studied using NMR T(2) relaxometry and measurements of water-binding capacity (WBC) by centrifugation. Significant effects of temperature (raw, 40, 50, or 60°C), holding time (1s, 3, 6, or 9min......), and addition of carrot fibre on the distribution and mobility of water were found. However, the effect of carrot fibre could not be explained by structural changes in the sausages when examined by confocal laser scanning microscopy (CLSM). Correlations between T(2) relaxation measurements and WBC determined...... by centrifugation revealed that T(2) relaxation times were able to explain more than 90% of the variation in WBC for both non-pressure and pressure-treated sausages. However, only 49% of the variation was explained for pressure-treated sausages with carrot fibre, indicating that combining addition of fibre and high...

Thermal relaxation of molecular oxygen in collisions with nitrogen atoms

Energy Technology Data Exchange (ETDEWEB)

Andrienko, Daniil A., E-mail: daniila@umich.edu; Boyd, Iain D. [Department of Aerospace Engineering, University of Michigan, 1320 Beal Ave., Ann Arbor, Michigan 48108 (United States)

2016-07-07

Investigation of O{sub 2}–N collisions is performed by means of the quasi-classical trajectory method on the two lowest ab initio potential energy surfaces at temperatures relevant to hypersonic flows. A complete set of bound–bound and bound–free transition rates is obtained for each precollisional rovibrational state. Special attention is paid to the vibrational and rotational relaxations of oxygen as a result of chemically non-reactive interaction with nitrogen atoms. The vibrational relaxation of oxygen partially occurs via the formation of an intermediate NO{sub 2} complex. The efficient energy randomization results in rapid vibrational relaxation at low temperatures, compared to other molecular systems with a purely repulsive potential. The vibrational relaxation time, computed by means of master equation studies, is nearly an order of magnitude lower than the relaxation time in N{sub 2}–O collisions. The rotational nonequilibrium starts to play a significant effect at translational temperatures above 8000 K. The present work provides convenient relations for the vibrational and rotational relaxation times as well as for the quasi-steady dissociation rate coefficient and thus fills a gap in data due to a lack of experimental measurements for this system.

Idiosyncratic reality claims, relaxation dispositions, and ABC relaxation theory: happiness, literal christianity, miraculous powers, metaphysics, and the paranormal.

Science.gov (United States)

Smith, Jonathan C; Karmin, Aaron D

2002-12-01

This study examined idiosyncratic reality claims, that is, irrational or paranormal beliefs often claimed to enhance relaxation and happiness and reduce stress. The Smith Idiosyncratic Reality Claims Inventory and the Smith Relaxation Dispositions Inventory (which measures relaxation and stress dispositions, or enduring states of mind frequently associated with relaxation or stress) were given to 310 junior college student volunteers. Principal components factor analysis with varimax rotation identified five idiosyncratic reality claim factors: belief in Literal Christianity; Magic; Space Aliens: After Death experiences; and Miraculous Powers of Meditation, Prayer, and Belief. No factor correlated with increased relaxation dispositions Peace, Energy, or Joy, or reduced dispositional somatic stress, worry, or negative emotion on the Smith Relaxation Dispositions Inventory. It was concluded that idiosyncratic reality claims may not be associated with reported relaxation, happiness, or stress. In contrast, previous research strongly supported self-affirming beliefs with few paranormal assumptions display such an association.

Stretched exponential relaxation in molecular and electronic glasses

Science.gov (United States)

Phillips, J. C.

1996-09-01

Stretched exponential relaxation, 0034-4885/59/9/003/img1, fits many relaxation processes in disordered and quenched electronic and molecular systems, but it is widely believed that this function has no microscopic basis, especially in the case of molecular relaxation. For electronic relaxation the appearance of the stretched exponential is often described in the context of dispersive transport, where 0034-4885/59/9/003/img2 is treated as an adjustable parameter, but in almost all cases it is generally assumed that no microscopic meaning can be assigned to 0034-4885/59/9/003/img3 even at 0034-4885/59/9/003/img4, a glass transition temperature. We show that for molecular relaxation 0034-4885/59/9/003/img5 can be understood, providing that one separates extrinsic and intrinsic effects, and that the intrinsic effects are dominated by two magic numbers, 0034-4885/59/9/003/img6 for short-range forces, and 0034-4885/59/9/003/img7 for long-range Coulomb forces, as originally observed by Kohlrausch for the decay of residual charge on a Leyden jar. Our mathematical model treats relaxation kinetics using the Lifshitz - Kac - Luttinger diffusion to traps depletion model in a configuration space of effective dimensionality, the latter being determined using axiomatic set theory and Phillips - Thorpe constraint theory. The experiments discussed include ns neutron scattering experiments, particularly those based on neutron spin echoes which measure S( Q,t) directly, and the traditional linear response measurements which span the range from 0034-4885/59/9/003/img8 to s, as collected and analysed phenomenologically by Angell, Ngai, Böhmer and others. The electronic materials discussed include a-Si:H, granular 0034-4885/59/9/003/img9, semiconductor nanocrystallites, charge density waves in 0034-4885/59/9/003/img10, spin glasses, and vortex glasses in high-temperature semiconductors. The molecular materials discussed include polymers, network glasses, electrolytes and alcohols, Van

Hastelloy X fuel element creep relaxation and residual effects

International Nuclear Information System (INIS)

Castle, R.A.

1971-01-01

A worst case, seven element, asymmetric fuel, thermal environment was assumed and a creep relaxation analysis generated. The fuel element clad is .020 inch Hastelloy X. The contact load decreased from 11.6 pounds to 5.87 pounds in 100,000 hours. The residual stresses were then computed for various shutdown times. (U.S.)

Anomalous enthalpy relaxation in vitreous silica

DEFF Research Database (Denmark)

Yue, Yuanzheng

2015-01-01

scans. It is known that the liquid fragility (i.e., the speed of the viscous slow-down of a supercooled liquid at its Tg during cooling) has impact on enthalpy relaxation in glass. Here, we find that vitreous silica (as a strong system) exhibits striking anomalies in both glass transition and enthalpy...... relaxation compared to fragile oxide systems. The anomalous enthalpy relaxation of vitreous silica is discovered by performing the hyperquenching-annealing-calorimetry experiments. We argue that the strong systems like vitreous silica and vitreous Germania relax in a structurally cooperative manner, whereas...... the fragile ones do in a structurally independent fashion. We discuss the origin of the anomalous enthalpy relaxation in the HQ vitreous silica....

Dynamics of the α-relaxation in glass-forming polymers. Study by neutron scattering and relaxation techniques

Science.gov (United States)

Colmenero, J.

1993-12-01

The dynamics of the α-relaxation in three different polymeric systems, poly(vinyl methyl ether) (PVME), poly(vinyl chloride) (PVC) and poly(bisphenol A, 2-hydroxypropylether) (PH) has been studied by means of relaxation techniques and quasielastic neutron scattering (backscattering spectrometers IN10 and IN13 at the ILL-Grenoble). By using these techniques we have covered a wide time scale ranging from mesoscopic to macroscopic times (10 -10 -10 1 s). For analyzing the experimental data we have developed a phenomenological procedure in the frequency domain based on the Havriliak-Negami relaxation function, which in fact implies a Kohlrausch-Williams-Watts relaxation function in the time domain. The results obtained indicate that the dynamics of the α-relaxation in a wide time scale shows a clear non-Debye behaviour. The shape of the relaxation functions is found to be similar for the different techniques used and independent of temperature and momentum transfer ( Q). Moreover, the characteristic relaxation times deduced from the fitting of the experimental data can also be described using only one Vogel-Fulcher functional form. Besides we found that the Q-dependence of the relaxation times obtained by QENS is given by a power law, τ( Q) ∞ Q- n ( n>2), n being dependent on the system, and that the Q-behaviour and the non-Debye behaviour are directly correlated. In the case of PVC, time of flight (TOF) neutron scattering experiments confirm these results in a shorter time scale (2×10 -11 -2× 10 -12 s). Moreover, TOF results also suggest the possibility of interpreting the “fast process” usually detected in glass-forming systems as a Debye-like short regime of the α-relaxation.

Generalized extended Navier-Stokes theory: multiscale spin relaxation in molecular fluids.

Science.gov (United States)

Hansen, J S

2013-09-01

This paper studies the relaxation of the molecular spin angular velocity in the framework of generalized extended Navier-Stokes theory. Using molecular dynamics simulations, it is shown that for uncharged diatomic molecules the relaxation time decreases with increasing molecular moment of inertia per unit mass. In the regime of large moment of inertia the fast relaxation is wave-vector independent and dominated by the coupling between spin and the fluid streaming velocity, whereas for small inertia the relaxation is slow and spin diffusion plays a significant role. The fast wave-vector-independent relaxation is also observed for highly packed systems. The transverse and longitudinal spin modes have, to a good approximation, identical relaxation, indicating that the longitudinal and transverse spin viscosities have same value. The relaxation is also shown to be isomorphic invariant. Finally, the effect of the coupling in the zero frequency and wave-vector limit is quantified by a characteristic length scale; if the system dimension is comparable to this length the coupling must be included into the fluid dynamical description. It is found that the length scale is independent of moment of inertia but dependent on the state point.

Effects of the aging temperature and stress relaxation conditions on γ′ precipitation in Inconel X-750

Energy Technology Data Exchange (ETDEWEB)

Ha, Jeong Won [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Research and Development Center, KOS Limited, Yangsan 626-230 (Korea, Republic of); Seong, Baek Seok [Neutron Science Division, HANARO Center, Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Jeong, Hi Won [Advanced Metallic Materials Division, Korea Institute of Materials Science, Changwon 642-831 (Korea, Republic of); Choi, Yoon Suk [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of); Kang, Namhyun, E-mail: nhkang@pusan.ac.kr [Department of Materials Science and Engineering, Pusan National University, Busan 609-735 (Korea, Republic of)

2015-02-15

Highlights: • Stress relaxation after aging 620 °C increased carbides and maintained γ′ fraction. • Aging temperature increase to 732 °C raised the γ′ increment after stress relaxation. • Small increase of carbides induced the large increase of γ′ after stress relaxation. • Loading for stress relaxation raised γ′ increment due to dislocation multiplication. - Abstract: Inconel X-750 is a Ni-based precipitation-hardened superalloy typically used in springs designed for high-temperature applications such as the hold-down springs in nuclear power plants. γ′ is a major precipitate in X-750 alloys which affects the strength, creep resistance, and stress relaxation properties of the spring. In this study, a solution-treated X-750 wire coiled into a spring was used that was aged at various temperatures and submitted to stress relaxation tests with and without loading. Small angle neutron scattering was employed to quantify the size and volume fraction of γ′ phase in the springs as a function of the aging temperature and the application of a load during stress relaxation. The volume fraction of γ′ precipitates increased in the specimen aged at 732 °C following stress relaxation at 500 °C for 300 h. However, the mean size of the precipitates in the samples was not affected by stress relaxation. The specimen aged at the lower temperature (620 °C) contained a smaller γ′ volume fraction and gained a smaller fraction of γ′ during stress relaxation compared with the sample aged at the higher temperature (732 °C). The smaller increase in the γ′ volume fraction for the sample aged at 620 °C was associated with a larger increase in the M{sub 23}C{sub 6} secondary carbide content during relaxation. The Cr depletion zone around the secondary carbides raises the solubility of γ′ thereby decreasing the volume fraction of γ′ precipitates in Inconel X-750. In terms of stress relaxation, a larger increase in the γ′ volume fraction was

Simultaneously Suppressing Low-Frequency and Relaxation Oscillation Intensity Noise in a DBR Single-Frequency Phosphate Fiber Laser

International Nuclear Information System (INIS)

Xiao Yu; Li Can; Xu Shan-Hui; Feng Zhou-Ming; Yang Chang-Sheng; Zhao Qi-Lai; Yang Zhong-Min

2015-01-01

Effective multiple optoelectronic feedback circuits for simultaneously suppressing low-frequency and relaxation oscillation intensity noise in a single-frequency phosphate fiber laser are demonstrated. The forward transfer function, which relates the laser output intensity to the pump modulations, is measured and analyzed. A custom two-path feedback system operating at different frequency bands is designed to adjust the pump current directly. The relative intensity noise is decreased by 20 dB from 0.2 to 5kHz and over 10 dB from 5 to 10 kHz. The relaxation oscillation peak is suppressed by 22 dB. In addition, a long term (24 h) laser instability of less than 0.05% is achieved. (paper)

The relationships between suggestibility, influenceability, and relaxability.

Science.gov (United States)

Polczyk, Romuald; Frey, Olga; Szpitalak, Malwina

2013-01-01

This research explores the relationships between relaxability and various aspects of suggestibility and influenceability. The Jacobson Progressive Muscle Relaxation procedure was used to induce relaxation. Tests of direct suggestibility, relating to the susceptibility of overt suggestions, and indirect suggestibility, referring to indirect hidden influence, as well as self-description questionnaires on suggestibility and the tendency to comply were used. Thayer's Activation-Deactivation Adjective Check List, measuring various kinds of activation and used as a pre- and posttest, determined the efficacy of the relaxation procedure. Indirect, direct, and self-measured suggestibility proved to be positively related to the ability to relax, measured by Thayer's subscales relating to emotions. Compliance was not related to relaxability. The results are discussed in terms of the aspects of relaxation training connected with suggestibility.

Dynamics and relaxation in confined medium. Application to 129Xe magnetic relaxation in Vycor

International Nuclear Information System (INIS)

Pasquier, Virginie

1995-01-01

Porous media morphology and topology drive the exploration of pore space by fluid. So, analysis of transport process, associated with relaxation mechanism, allows indirect study of pore geometry. The purpose of this work is to understand better the relation between geometry and transport. This study involves two parts: a modelization and prediction step is followed by an experimental application of magnetic relaxation. Numerical simulations and analytical models allow to quantify the influence on the solid interface of the dynamical behavior of confined gas in disordered porous media (granular structure and porous network) or in common geometry (cylindrical and lamellar interfaces). The formalism of diffusion propagator is a powerful tool to quantify the influence of the pore geometry on the diffusion of confined gas. The propagator holds all dynamical information on the system; it also predicts the temporal evolution of the autocorrelation functions of the Hamiltonian describing local coupling. In an intermediate time scale, magnetic relaxation shows complex diffusional regime: the autocorrelation functions decrease in a power law with a exponent smaller than d/2 (where d is the Euclidian dimension of the system). This behavior is analogous to dynamic in low-dimensional space, but here arises from surface correlations of the porous media. The long-time behavior of the autocorrelation functions retrieves the asymptotic decrease t -d/2 . Moreover, atypical behavior is observed for the Knudsen diffusion between infinite planes. It turns out that 129 Xe NMR is a appropriate technique to characterize organization and diffusion of gas confined in Vycor. Systematic studies of temperature and pressure effect on the 129 Xe chemical shift allow to specify the Xe/solid interaction. The analysis of the relaxation measurements, thanks to the numerical development, confirms conclusions arising from the study of diffusion propagator. (author) [fr

Differential Effectiveness of Electromyograph Feedback, Verbal Relaxation Instructions, and Medication Placebo with Tension Headaches

Science.gov (United States)

Cox, Daniel J.; And Others

1975-01-01

Adults with chronic tension headaches were assigned to auditory electromyograph (EMG) feedback (N=9), to progressive relaxation (N=9), and to placebo treatment (N=9). Data indicated that biofeedback and verbal relaxation instructions were equally superior to the medicine placebo on all measured variables in the direction of clinical improvement,…

Relaxation of Anisotropic Glasses

DEFF Research Database (Denmark)

Deubener, Joachim; Martin, Birgit; Wondraczek, Lothar

2004-01-01

. When the load was removed at room temperature a permanent optical anisotropy (birefringence) was observed only perpendicular to cylinder axis and the pressure direction indicating complete elimination of thermal stresses. Relaxation of structural anisotropy was studied from reheating experiments using...... the energy release, thermo-mechanical and optical relaxation behaviour are drawn....

The Effect of Benson Relaxation on Quality of Life of Patients with Irritable Bowel Syndrome

Directory of Open Access Journals (Sweden)

Asadi

2016-09-01

Full Text Available Background Irritable bowel syndrome (IBS is one of the most common functional disorders of the lower gastrointestinal tract that is characterized by abdominal pain and changes in bowel habits. This disorder changes the quality of life of patients. Objectives The purpose of this study was to determine the effect of Benson relaxation on quality of life of patients with irritable bowel syndrome. Methods This was a clinical trial study with 46 patients, who were randomly divided to two groups including Benson relaxation and control group. The experimental group exercised 20 minutes daily for three two months, while no intervention program was held for the control group. The data collection tools were a demographic form and SF-34 Questionnaire that were used to gather data one week before and two months after the intervention. Then data were analyzed using the SPSS version 19 software. Results The results indicated the mean total quality of life score in test group after intervention was changed from 93.13 to 57.61 while the control group was changed from 105.65 to 96.43 (P ≤ 0.001. There was a significant difference in six dimensions of quality of life including dysphoria (P ≤ 0.001, social reaction (P ≤ 0.001, health worry (P ≤ 0.001, body image (P ≤ 0.001, interpersonal relation (P = 0.004 and activities interference (P = 0.001 between the two groups, but no significant difference was found in food abstinence (P = 0.244 and sexual worry (P = 0.830. Conclusions The findings showed that Benson relaxation training might be an effective therapy for improving quality of life in patients with IBS.

Charge Relaxation Dynamics of an Electrolytic Nanocapacitor

Science.gov (United States)

2015-01-01

Understanding ion relaxation dynamics in overlapping electric double layers (EDLs) is critical for the development of efficient nanotechnology-based electrochemical energy storage, electrochemomechanical energy conversion, and bioelectrochemical sensing devices as well as the controlled synthesis of nanostructured materials. Here, a lattice Boltzmann (LB) method is employed to simulate an electrolytic nanocapacitor subjected to a step potential at t = 0 for various degrees of EDL overlap, solvent viscosities, ratios of cation-to-anion diffusivity, and electrode separations. The use of a novel continuously varying and Galilean-invariant molecular-speed-dependent relaxation time (MSDRT) with the LB equation recovers a correct microscopic description of the molecular-collision phenomena and enhances the stability of the LB algorithm. Results for large EDL overlaps indicated oscillatory behavior for the ionic current density, in contrast to monotonic relaxation to equilibrium for low EDL overlaps. Further, at low solvent viscosities and large EDL overlaps, anomalous plasmalike spatial oscillations of the electric field were observed that appeared to be purely an effect of nanoscale confinement. Employing MSDRT in our simulations enabled modeling of the fundamental physics of the transient charge relaxation dynamics in electrochemical systems operating away from equilibrium wherein Nernst–Einstein relation is known to be violated. PMID:25678941

Microplastic relaxations of single and polycrystalline molybdenum

Energy Technology Data Exchange (ETDEWEB)

Pichl, W.; Weiss, B. [Wien Univ. (Austria). Inst. fuer Materialphysik; Chen, D.L.

1998-05-01

The microplasticity of high-purity molybdenum single crystals and of Mo polycrystals of technical purity has been investigated by relaxation step tests in uniaxial compression. A new model for the evaluation of relaxation tests in the microplastic range of b.c.c metals is presented which takes into account the decrease of the mobile dislocation density due to exhaustion of non-screw dislocations. The model allows an independent determination of the activation volume and of the microstructure parameters controlling dislocation exhaustion. The results indicate that in the high-purity single crystals the deformation rate is controlled by interactions of non-screw dislocations with the grown-in network. In the polycrystals additional interactions with impurity atoms seem to occur. In the single crystals the activity and subsequent exhaustion of two different glide systems was observed, followed by a gradual onset of screw dislocation motion. (orig.) 26 refs.

Stress relaxation in viscous soft spheres.

Science.gov (United States)

Boschan, Julia; Vasudevan, Siddarth A; Boukany, Pouyan E; Somfai, Ellák; Tighe, Brian P

2017-10-04

We report the results of molecular dynamics simulations of stress relaxation tests in athermal viscous soft sphere packings close to their unjamming transition. By systematically and simultaneously varying both the amplitude of the applied strain step and the pressure of the initial condition, we access both linear and nonlinear response regimes and control the distance to jamming. Stress relaxation in viscoelastic solids is characterized by a relaxation time τ* that separates short time scales, where viscous loss is substantial, from long time scales, where elastic storage dominates and the response is essentially quasistatic. We identify two distinct plateaus in the strain dependence of the relaxation time, one each in the linear and nonlinear regimes. The height of both plateaus scales as an inverse power law with the distance to jamming. By probing the time evolution of particle velocities during relaxation, we further identify a correlation between mechanical relaxation in the bulk and the degree of non-affinity in the particle velocities on the micro scale.

Soluble organic additive effects on stress development during drying of calcium carbonate suspensions.

Science.gov (United States)

Wedin, Pär; Lewis, Jennifer A; Bergström, Lennart

2005-10-01

The effect of polymer, plasticizer, and surfactant additives on stress development during drying of calcium carbonate particulate coatings was studied using a controlled-environment apparatus that simultaneously monitors drying stress, weight loss, and relative humidity. We found that the calcium carbonate coatings display a drying stress evolution typical of granular films, which is characterized by a sharp capillary-induced stress rise followed by a rapid stress relaxation. The addition of a soluble polymer to the CaCO3 suspension resulted in a two-stage stress evolution process. The initial stress rise stems from capillary-pressure-induced stresses within the film, while the second, larger stress rise occurs due to solidification and shrinkage of the polymeric species. Measurements on the corresponding pure polymer solutions established a clear correlation between the magnitude of residual stress in both the polymer and CaCO3-polymer films to the physical properties of the polymer phase, i.e. its glass transition temperature, T(g), and Young's modulus. The addition of small organic molecules can reduce the residual stress observed in the CaCO3-polymer films; e.g., glycerol, which acts as a plasticizer, reduces the drying stress by lowering T(g), while surfactant additions reduce the surface tension of the liquid phase, and, hence, the magnitude of the capillary pressure within the film.

Immersed Boundary-Lattice Boltzmann Method Using Two Relaxation Times

Directory of Open Access Journals (Sweden)

Kosuke Hayashi

2012-06-01

Full Text Available An immersed boundary-lattice Boltzmann method (IB-LBM using a two-relaxation time model (TRT is proposed. The collision operator in the lattice Boltzmann equation is modeled using two relaxation times. One of them is used to set the fluid viscosity and the other is for numerical stability and accuracy. A direct-forcing method is utilized for treatment of immersed boundary. A multi-direct forcing method is also implemented to precisely satisfy the boundary conditions at the immersed boundary. Circular Couette flows between a stationary cylinder and a rotating cylinder are simulated for validation of the proposed method. The method is also validated through simulations of circular and spherical falling particles. Effects of the functional forms of the direct-forcing term and the smoothed-delta function, which interpolates the fluid velocity to the immersed boundary and distributes the forcing term to fixed Eulerian grid points, are also examined. As a result, the following conclusions are obtained: (1 the proposed method does not cause non-physical velocity distribution in circular Couette flows even at high relaxation times, whereas the single-relaxation time (SRT model causes a large non-physical velocity distortion at a high relaxation time, (2 the multi-direct forcing reduces the errors in the velocity profile of a circular Couette flow at a high relaxation time, (3 the two-point delta function is better than the four-point delta function at low relaxation times, but worse at high relaxation times, (4 the functional form of the direct-forcing term does not affect predictions, and (5 circular and spherical particles falling in liquids are well predicted by using the proposed method both for two-dimensional and three-dimensional cases.

Relaxation techniques for stress

Science.gov (United States)

... raise your heart rate. This is called the stress response. Relaxation techniques can help your body relax and lower your blood pressure ... also many other types of breathing techniques you can learn. In many cases, you do not need much ... including those that cause stress. Meditation has been practiced for thousands of years, ...

Relaxation Dynamics of Nanoparticle-Tethered Polymer Chains

KAUST Repository

Kim, Sung A

2015-09-08

© 2015 American Chemical Society. Relaxation dynamics of nanoparticle-tethered cis-1,4-polyisoprene (PI) are investigated using dielectric spectroscopy and rheometry. A model system composed of polymer chains densely grafted to spherical SiO2 nanoparticles to form self-suspended suspensions facilitates detailed studies of slow global chain and fast segmental mode dynamics under surface and geometrical confinement-from experiments performed in bulk materials. We report that unentangled polymer molecules tethered to nanoparticles relax far more slowly than their tethered entangled counterparts. Specifically, at fixed grafting density we find, counterintuitively, that increasing the tethered polymer molecular weight up to values close to the entanglement molecular weight speeds up chain relaxation dynamics. Decreasing the polymer grafting density for a fixed molecular weight has the opposite effect: it dramatically slows down chain relaxation, increases interchain coupling, and leads to a transition in rheological response from simple fluid behavior to viscoelastic fluid behavior for tethered PI chains that are unentangled by conventional measures. Increasing the measurement temperature produces an even stronger elastic response and speeds up molecular relaxation at a rate that decreases with grafting density and molecular weight. These observations are discussed in terms of chain confinement driven by crowding between particles and by the existence of an entropic attractive force produced by the space-filling constraint on individual chains in a self-suspended material. Our results indicate that the entropic force between densely grafted polymer molecules couples motions of individual chains in an analogous manner to reversible cross-links in associating polymers.

Model and prediction of stress relaxation of polyurethane fiber

Science.gov (United States)

You, Gexin; Wang, Chunyan; Mei, Shuqin; Yang, Bo; Zhou, Xiuwen

2018-03-01

In this study, the effect of small strain (less than 10%) on hydrogen bond (H-bond) and crystallinity of dry-spun polyurethane fiber was investigated with fourier transform infrared spectroscopy and x-ray diffractometer, respectively. The results showed that the H-bond of hard segments hardly broke and its degree of crystallinity scarcely varied below strain of 10%. The fiber stress relaxation behavior at 25 °C under small strain was researched using dynamic mechanical analyzer. The stress relaxation modulus constitutive equation was obtained by transforming the non-linear relationship between stress and time into the linear relationship between stress and strain. The stress relaxation modulus master curve at 25 °C was established in terms of short-term stress relaxation tests at elevated temperatures (35 °C, 45 °C, 65 °C and 75 °C) according to time-temperature superposition principle (TTS) to predict long-term behavior within 353 year.

Acrolein relaxes mouse isolated tracheal smooth muscle via a TRPA1-dependent mechanism.

Science.gov (United States)

Cheah, Esther Y; Burcham, Philip C; Mann, Tracy S; Henry, Peter J

2014-05-01

Airway sensory C-fibres express TRPA1 channels which have recently been identified as a key chemosensory receptor for acrolein, a toxic and highly prevalent component of smoke. TRPA1 likely plays an intermediary role in eliciting a range of effects induced by acrolein including cough and neurogenic inflammation. Currently, it is not known whether acrolein-induced activation of TRPA1 produces other airway effects including relaxation of mouse airway smooth muscle. The aims of this study were to examine the effects of acrolein on airway smooth muscle tone in mouse isolated trachea, and to characterise the cellular and molecular mechanisms underpinning the effects of acrolein. Isometric tension recording studies were conducted on mouse isolated tracheal segments to characterise acrolein-induced relaxation responses. Release of the relaxant PGE₂ was measured by EIA to examine its role in the response. Use of selective antagonists/inhibitors permitted pharmacological characterisation of the molecular and cellular mechanisms underlying this relaxation response. Acrolein induced dose-dependent relaxation responses in mouse isolated tracheal segments. Importantly, these relaxation responses were significantly inhibited by the TRPA1 antagonists AP-18 and HC-030031, an NK₁ receptor antagonist RP-67580, and the EP₂ receptor antagonist PF-04418948, whilst completely abolished by the non-selective COX inhibitor indomethacin. Acrolein also caused rapid PGE₂ release which was suppressed by HC-030031. In summary, acrolein induced a novel bronchodilator response in mouse airways. Pharmacologic studies indicate that acrolein-induced relaxation likely involves interplay between TRPA1-expressing airway sensory C-fibres, NK₁ receptor-expressing epithelial cells, and EP₂-receptor expressing airway smooth muscle cells. Copyright © 2014 Elsevier Inc. All rights reserved.

Research on Creep Relaxation Non-uniformity and Effect on Performance of Combined Rotor

Science.gov (United States)

Liu, Qingya; He, Jingfei; Zhao, Lijia

2017-11-01

The combined rotor of gas turbine is connected by a certain number of rod bolts. It works in the high temperature environment for a long time, and the rod bolts will creep and relax. Under the influence of elastic interaction, the loss of pretightening force of rod bolts at different positions is non-uniform, which will cause the connection of the combined rotor to be out of tune. In this paper, the creep relaxation non-uniformity model for a class F heavy duty gas turbine is established. On the basis of this, the performance degradation and structural strength change of combined rotor resulting from creep relaxation non-uniformity of rod bolts are studied. The results show that the ratio of preload mistuning increases with time and then converges, and there is a threshold inflection point in about seven thousand hours.

Effects of Twenty-four Move Shadow Boxing Combined with psychosomatic relaxation on Depression and Anxiety in Patients with Type-2 Diabetes.

Science.gov (United States)

Zheng, Yingying; Zhou, Yiyi; Lai, Qiujia

2015-06-01

The aim of the current study was to observe the effects of Twenty-four Move Shadow Boxing combined with psychosomatic relaxation on depression and anxiety in patients with Type-2 Diabetes. One hundred and twenty (120) patients with Type-2 Diabetes and depressive/anxious symptoms were divided into intervention group (60 cases) and control group (60 cases) according to the minimum distribution principle of unbalanced indicators. Twenty-four Move Shadow Boxing group used this intervention combined with psychosomatic relaxation. Control group underwent conventional treatment. All the patients in the two groups completed the Self-rating Depression Scale (SDS) and Self-Rating Anxiety Scale (SAS) before and after treatment. Among the 52 people included in the statistical analysis, the recovery rate was 13.3%. The differences between depression and anxiety scores in the intervention group before and after treatment were statistically significant (PBoxing and psychosomatic relaxation has a beneficial auxiliary therapeutic effect on depression and anxiety accompanying Type-2 Diabetes.

Mechanical torques generated by optically pumped atomic spin relaxation at surfaces

International Nuclear Information System (INIS)

Herman, R.M.

1982-01-01

It is argued that a valuable method of observing certain types of surface-atom interactions may lie in mechanical torques generated through the spin-orbit relaxation of valence electronic spins of optically pumped atoms at surfaces. The unusual feature of this phenomenon is that the less probable spin-orbit relaxation becomes highly visible as compared with the much more rapid paramagnetic relaxation, because of an enhancement, typically by as much as a factor 10 9 , in the torques delivered to mechanical structures, by virtue of a very large effective moment arm. Spin-orbit relaxation operates through an exchange of translational momentum which, in turn, can be identified with the delivery of a gigantic angular momentum (in units of h) relative to a distant axis about which mechanical motion is referred. The spin-orbit relaxation strongly depends upon the atomic number of the surface atoms and the strength of interaction with the optically pumped atoms. Being dominated by high-atomic-number surface atoms, spin-orbit relaxation rates may not be too strongly influenced by minor surface contamination of lighter-weight optically active atoms

Mechanical torques generated by optically pumped atomic spin relaxation at surfaces

Science.gov (United States)

Herman, R. M.

1982-03-01

It is argued that a valuable method of observing certain types of surface-atom interactions may lie in mechanical torques generated through the spin-orbit relaxation of valence electronic spins of optically pumped atoms at surfaces. The unusual feature of this phenomenon is that the less probable spin-orbit relaxation becomes highly visible as compared with the much more rapid paramagnetic relaxation, because of an enhancement, typically by as much as a factor 109, in the torques delivered to mechanical structures, by virtue of a very large effective moment arm. Spin-orbit relaxation operates through an exchange of translational momentum which, in turn, can be identified with the delivery of a gigantic angular momentum (in units of ℏ) relative to a distant axis about which mechanical motion is referred. The spin-orbit relaxation strongly depends upon the atomic number of the surface atoms and the strength of interaction with the optically pumped atoms. Being dominated by high-atomic-number surface atoms, spin-orbit-relaxation rates may not be too strongly influenced by minor surface contamination of lighter-weight optically active atoms.

Aging of the Johari-Goldstein relaxation in the glass-forming liquids sorbitol and xylitol

Science.gov (United States)

Yardimci, Hasan; Leheny, Robert L.

2006-06-01

Employing frequency-dependent dielectric susceptibility we characterize the aging in two supercooled liquids, sorbitol and xylitol, below their calorimetric glass transition temperatures. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibility of both liquids possesses a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench through the glass transition, the susceptibility slowly approaches the equilibrium behavior. For both liquids, the magnitude of the Johari-Goldstein relaxation displays a dependence on the time since the quench, or aging time, that is quantitatively very similar to the age dependence of the alpha peak frequency. The Johari-Goldstein relaxation time remains constant during aging for sorbitol while it decreases slightly with age for xylitol. Hence, one cannot sensibly assign a fictive temperature to the Johari-Goldstein relaxation. This behavior contrasts with that of liquids lacking distinct Johari-Goldstein peaks for which the excess wing of the alpha peak tracks the main part of the peak during aging, enabling the assignment of a single fictive temperature to the entire spectrum. The aging behavior of the Johari-Goldstein relaxation time further calls into question the possibility that the relaxation time possesses stronger temperature dependence in equilibrium than is observed in the out-of-equilibrium state below the glass transition.

Conductivity-Relaxation Relations in Nanocomposite Polymer Electrolytes Containing Ionic Liquid.

Science.gov (United States)

Shojaatalhosseini, Mansoureh; Elamin, Khalid; Swenson, Jan

2017-10-19

In this study, we have used nanocomposite polymer electrolytes, consisting of poly(ethylene oxide) (PEO), δ-Al 2 O 3 nanoparticles, and lithium bis(trifluoromethanesolfonyl)imide (LiTFSI) salt (with 4 wt % δ-Al 2 O 3 and PEO:Li ratios of 16:1 and 8:1), and added different amounts of the ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesolfonyl)imide (BMITFSI). The aim was to elucidate whether the ionic liquid is able to dissociate the Li-ions from the ether oxygens and thereby decouple the ionic conductivity from the segmental polymer dynamics. The results from DSC and dielectric spectroscopy show that the ionic liquid speeds up both the segmental polymer dynamics and the motion of the Li + ions. However, a close comparison between the structural (α) relaxation process, given by the segmental polymer dynamics, and the ionic conductivity shows that the motion of the Li + ions decouples from the segmental polymer dynamics at higher concentrations of the ionic liquid (≥20 wt %) and instead becomes more related to the viscosity of the ionic liquid. This decoupling increases with decreasing temperature. In addition to the structural α-relaxation, two more local relaxation processes, denoted β and γ, are observed. The β-relaxation becomes slightly faster at the highest concentration of the ionic liquid (at least for the lower salt concentration), whereas the γ-relaxation is unaffected by the ionic liquid, over the whole concentration range 0-40 wt %.

Spin-relaxation time in the impurity band of wurtzite semiconductors

Science.gov (United States)

Tamborenea, Pablo I.; Wellens, Thomas; Weinmann, Dietmar; Jalabert, Rodolfo A.

2017-09-01

The spin-relaxation time for electrons in the impurity band of semiconductors with wurtzite crystal structure is determined. The effective Dresselhaus spin-orbit interaction Hamiltonian is taken as the source of the spin relaxation at low temperature and for doping densities corresponding to the metallic side of the metal-insulator transition. The spin-flip hopping matrix elements between impurity states are calculated and used to set up a tight-binding Hamiltonian that incorporates the symmetries of wurtzite semiconductors. The spin-relaxation time is obtained from a semiclassical model of spin diffusion, as well as from a microscopic self-consistent diagrammatic theory of spin and charge diffusion in doped semiconductors. Estimates are provided for particularly important materials. The theoretical spin-relaxation times compare favorably with the corresponding low-temperature measurements in GaN and ZnO. For InN and AlN we predict that tuning of the spin-orbit coupling constant induced by an external potential leads to a potentially dramatic increase of the spin-relaxation time related to the mechanism under study.

Sandpile model for relaxation in complex systems

International Nuclear Information System (INIS)

Vazquez, A.; Sotolongo-Costa, O.; Brouers, F.

1997-10-01

The relaxation in complex systems is, in general, nonexponential. After an initial rapid decay the system relaxes slowly following a long time tail. In the present paper a sandpile moderation of the relaxation in complex systems is analysed. Complexity is introduced by a process of avalanches in the Bethe lattice and a feedback mechanism which leads to slower decay with increasing time. In this way, some features of relaxation in complex systems: long time tails relaxation, aging, and fractal distribution of characteristic times, are obtained by simple computer simulations. (author)

Nonpolar ZnO film growth and mechanism for anisotropic in-plane strain relaxation

International Nuclear Information System (INIS)

Pant, P.; Budai, J.D.; Narayan, J.

2010-01-01

Using high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction, we investigated the strain relaxation mechanisms for nonpolar (1 1 -2 0) a-plane ZnO epitaxy on (1 -1 0 2) r-plane sapphire, where the in-plane misfit ranges from -1.5% for the [0 0 0 1]ZnO-parallel [1 -1 0 -1]sapphire to -18.3% for the [-1 1 0 0]ZnO-parallel [-1 -1 2 0]sapphire direction. For the large misfit [-1 1 0 0]ZnO direction the misfit strains are fully relaxed at the growth temperature, and only thermal misfit and defect strains, which cannot be relaxed fully by slip dislocations, remain on cooling. For the small misfit direction, lattice misfit is not fully relaxed at the growth temperature. As a result, additive unrelaxed lattice and thermal misfit and defect strains contribute to the measured strain. Our X-ray diffraction measurements of lattice parameters show that the anisotropic in-plane biaxial strain leads to a distortion of the hexagonal symmetry of the ZnO basal plane. Based on the anisotropic strain relaxation observed along the orthogonal in-plane [-1 1 0 0] and [0 0 0 1]ZnO stress directions and our HRTEM investigations of the interface, we show that the plastic relaxation occurring in the small misfit direction [0 0 0 1]ZnO by dislocation nucleation is incomplete. These results are consistent with the domain-matching paradigm of a complete strain relaxation for large misfits and a difficulty in relaxing the film strain for small misfits.

Spectroscopic Studies of the Super Relaxed State of Skeletal Muscle.

Directory of Open Access Journals (Sweden)

Leonardo Nogara

Full Text Available In the super-relaxed state of myosin, ATPase activity is strongly inhibited by binding of the myosin heads to the core of the thick filament in a structure known as the interacting-heads motif. In the disordered relaxed state myosin heads are not bound to the core of the thick filament and have an ATPase rate that is 10 fold greater. In the interacting-heads motif the two regulatory light chains appear to bind to each other. We have made single cysteine mutants of the regulatory light chain, placed both paramagnetic and fluorescent probes on them, and exchanged them into skinned skeletal muscle fibers. Many of the labeled light chains tended to disrupt the stability of the super-relaxed state, and showed spectral changes in the transition from the disordered relaxed state to the super-relaxed state. These data support the putative interface between the two regulatory light chains identified by cryo electron microscopy and show that both the divalent cation bound to the regulatory light chain and the N-terminus of the regulatory light chain play a role in the stability of the super-relaxed state. One probe showed a shift to shorter wavelengths in the super-relaxed state such that a ratio of intensities at 440nm to that at 520nm provided a measure of the population of the super-relaxed state amenable for high throughput screens for finding potential pharmaceuticals. The results provide a proof of concept that small molecules that bind to this region can destabilize the super-relaxed state and provide a method to search for small molecules that do so leading to a potentially effective treatment for Type 2 diabetes and obesity.

Effects of the strain relaxation of an AlGaN barrier layer induced by various cap layers on the transport properties in AlGaN/GaN heterostructures

International Nuclear Information System (INIS)

Liu Zi-Yang; Zhang Jin-Cheng; Duan Huan-Tao; Xue Jun-Shuai; Lin Zhi-Yu; Ma Jun-Cai; Xue Xiao-Yong; Hao Yue

2011-01-01

The strain relaxation of an AlGaN barrier layer may be influenced by a thin cap layer above, and affects the transport properties of AlGaN/GaN heterostructures. Compared with the slight strain relaxation found in AlGaN barrier layer without cap layer, it is found that a thin cap layer can induce considerable changes of strain state in the AlGaN barrier layer. The degree of relaxation of the AlGaN layer significantly influences the transport properties of the two-dimensional electron gas (2DEG) in AlGaN/GaN heterostructures. It is observed that electron mobility decreases with the increasing degree of relaxation of the AlGaN barrier, which is believed to be the main cause of the deterioration of crystalline quality and morphology on the AlGaN/GaN interface. On the other hand, both GaN and AlN cap layers lead to a decrease in 2DEG density. The reduction of 2DEG caused by the GaN cap layer may be attributed to the additional negative polarization charges formed at the interface between GaN and AlGaN, while the reduction of the piezoelectric effect in the AlGaN layer results in the decrease of 2DEG density in the case of AlN cap layer. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

Relaxation Time of High-Density Amorphous Ice

Science.gov (United States)

Handle, Philip H.; Seidl, Markus; Loerting, Thomas

2012-06-01

Amorphous water plays a fundamental role in astrophysics, cryoelectron microscopy, hydration of matter, and our understanding of anomalous liquid water properties. Yet, the characteristics of the relaxation processes taking place in high-density amorphous ice (HDA) are unknown. We here reveal that the relaxation processes in HDA at 110-135 K at 0.1-0.2 GPa are of collective and global nature, resembling the alpha relaxation in glassy material. Measured relaxation times suggest liquid-like relaxation characteristics in the vicinity of the crystallization temperature at 145 K. By carefully relaxing pressurized HDA for several hours at 135 K, we produce a state that is closer to the ideal glass state than all HDA states discussed so far in literature.

Vibrational relaxation dynamics of SD molecules in As2S3: Observation of an anomalous isotope effect

International Nuclear Information System (INIS)

Engholm, J.R.; Happek, U.; Rella, C.W.

1995-01-01

It is generally assumed that the vibrational relaxation of molecular impurities in crystals and glasses mainly depends on the order of the decay process, with lower order processes leading to more rapid relaxation (a behavior that is known under the term open-quotes gap-lawclose quotes). Here we present measurements that contradict this assumption. Using high intensity psec pulses of the Stanford FEL we measured the relaxation rate of the SD vibrational stretch mode (at a frequency of 1800 cm) by applying a pump-probe technique. We find relaxation rates on the order of 2x10 9 sec -1 , which are a factor of 2 lower than those found for the isotope molecule SH (at a frequency of about 2500 cm - 1 ) in the same host 1 . We recall that the relaxation of the SD vibrational stretch mode is controlled by a lower order process as compared to the SH molecule, which is due to the smaller number of host vibrational quanta to match the energy of the stretch mode; a fact we have confirmed experimentally by temperature dependent relaxation measurements. Thus our remits are in marked contrast to the so-called open-quotes Gap-Lawclose quotes and emphasize the importance of the molecule - host coupling in the relaxation dynamics

Dielectric and mechanical relaxation in isooctylcyanobiphenyl (8*OCB)

Energy Technology Data Exchange (ETDEWEB)

Pawlus, S; Mierzwa, M; Paluch, M; Rzoska, S J [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Roland, C M, E-mail: michal.mierzwa@us.edu.p [Chemistry Division, Naval Research Laboratory, Code 6120, Washington, DC 20375-5342 (United States)

2010-06-16

The dynamics of isooctylcyanobiphenyl (8*OCB) was characterized using dielectric and mechanical spectroscopies. This isomer of the liquid crystalline octylcyanobiphenyl (8OCB) vitrifies during cooling or on application of pressure, exhibiting the typical features of glass-forming liquids: non-Debye relaxation function, non-Arrhenius temperature dependence of the relaxation times, {tau}{sub {alpha}}, a dynamic crossover at T {approx} 1.6T{sub g}. This crossover is evidenced by changes in the behavior of both the peak shape and the temperature dependence of {tau}{sub {alpha}}. The primary relaxation time at the crossover, 2 ns at ambient pressure, is the smallest value reported to date for any molecular liquid or polymer. Interestingly, at all temperatures below this crossover, {tau}{sub {alpha}}and the dc conductivity remain coupled (i.e., conform to the Debye-Stokes-Einstein relation). Two secondary relaxations are observed in the glassy state, one of which is identified as the Johari-Goldstein process. Unlike the case for 8OCB, no liquid crystalline phase could be attained for 8*OCB, demonstrating that relatively small differences in chemical structure can effect substantial changes in the intermolecular potential.

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

International Nuclear Information System (INIS)

Liu, Yuzhu; Knopp, Gregor; Qin, Chaochao; Gerber, Thomas

2015-01-01

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S 2 to S 1 is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S 2 state to the vibrationally hot S 1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S 1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding

Sawtooth oscillations as MHD relaxation process in a plasma

International Nuclear Information System (INIS)

Yoshida, Zensho; Inoue, Nobuyuki; Ogawa, Yuichi

1992-01-01

The sawtooth oscillation in a tokamak plasma is a spontaneous relaxation process accompanying global instabilities which behave to reduce the internal magnetic energy. This phenomenon has a similarity to the MHD relaxation processes in Reversed Field Pinch (RFP) and Ultra Low Q (ULQ) plasmas. The self-stabilizing effect of instabilities with m (poloidal mode number) = 1 results in an increase in the central safety factor q(0). Nonlinear dynamics of m = 1 instabilities has been discussed both for global and local modes. The latter appears when a pitch minimum exists in the plasma, and is relevant to the compound sawtooth oscillation. The MHD relaxation is a restructuring process of the plasma current profile that is competitive with the resistive diffusion. (author)

Tensions relaxation in Zircaloy-4

International Nuclear Information System (INIS)

Cuniberti, A.M.; Picasso, A.C.

1990-01-01

Traction and stress relaxation studies were performed on polycrystalline Zry-4 at room temperature. The effect of loading velocity on the plastic behaviour of the material is discussed, analysing log σ vs. log dε/dt at different deformation levels. The contribution introduced by the testing machine was taken into account in data evaluation. (Author). 7 refs., 3 figs., 3 tabs

Hair Dye and Hair Relaxers

Science.gov (United States)

... For Consumers Consumer Information by Audience For Women Hair Dye and Hair Relaxers Share Tweet Linkedin Pin it More sharing ... products. If you have a bad reaction to hair dyes and relaxers, you should: Stop using the ...

Observation of in-plane asymmetric strain relaxation during crystal growth and growth interruption in InGaAs/GaAs(001)

International Nuclear Information System (INIS)

Sasaki, Takuo; Shimomura, Kenichi; Kamiya, Itaru; Ohshita, Yoshio; Yamaguchi, Masafumi; Suzuki, Hidetoshi; Takahasi, Masamitu

2012-01-01

In-plane asymmetric strain relaxation in lattice-mismatched InGaAs/GaAs(001) heteroepitaxy is studied by in situ three-dimensional X-ray reciprocal space mapping. Repeating crystal growth and growth interruptions during measurements allows us to investigate whether the strain relaxation is limited at a certain thickness or saturated. We find that the degree of relaxation during growth interruption depends on both the film thickness and the in-plane directions. Significant lattice relaxation is observed in rapid relaxation regimes during interruption. This is a clear indication that relaxation is kinetically limited. In addition, relaxation along the [110] direction can saturate more readily than that along the [1-bar10] direction. We discuss this result in terms of the interaction between orthogonally aligned dislocations. (author)

The effects of strain relaxation on the dielectric properties of epitaxial ferroelectric Pb(Zr0.2Ti0.8)TiO3 thin films

Science.gov (United States)

Khan, Asif Islam; Yu, Pu; Trassin, Morgan; Lee, Michelle J.; You, Long; Salahuddin, Sayeef

2014-07-01

We study the effects of strain relaxation on the dielectric properties of epitaxial 40 nm Pb(Zr0.2Ti0.8)TiO3 (PZT) films. A significant increase in the defect and dislocation density due to strain relaxation is observed in PZT films with tetragonality c/a fatigue in ferroelectric materials.

Critical thickness and strain relaxation in high-misfit heteroepitaxial systems: PbTe1-xSex on PbSe (001)

International Nuclear Information System (INIS)

Wiesauer, Karin; Springholz, G.

2004-01-01

Strain relaxation and misfit dislocation formation is investigated for the high-misfit PbTe 1-x Se x /PbSe (001) heteroepitaxial system in which the lattice mismatch varies from 0% to 5.5%. Because a two-dimensional (2D) layer growth prevails for all PbTe 1-x Se x ternary compositions, the lattice mismatch is relaxed purely by misfit dislocations. In addition, it is found that strain relaxation is not hindered by dislocation kinetics. Therefore, this material combination is an ideal model system for testing the equilibrium Frank-van der Merwe and Matthews-Blakeslee strain relaxation models. In our experiments, we find significantly lower values of the critical layer thickness as compared to the model predictions. This discrepancy is caused by the inappropriate description of the dislocation self-energies when the layer thickness becomes comparable to the dislocation core radius. To resolve this problem, a modified expression for the dislocation self-energy is proposed. The resulting theoretical critical thicknesses are in excellent agreement with the experimental data. In addition, a remarkable universal scaling behavior is found for the strain relaxation data. This underlines the breakdown of the current strain relaxation models

The effect of prior lumbar surgeries on the flexion relaxation phenomenon and its responsiveness to rehabilitative treatment.

Science.gov (United States)

Neblett, Randy; Mayer, Tom G; Brede, Emily; Gatchel, Robert J

2014-06-01

Abnormal pretreatment flexion-relaxation in chronic disabling occupational lumbar spinal disorder patients has been shown to improve with functional restoration rehabilitation. Little is known about the effects of prior lumbar surgeries on flexion-relaxation and its responsiveness to treatment. To quantify the effect of prior lumbar surgeries on the flexion-relaxation phenomenon and its responsiveness to rehabilitative treatment. A prospective cohort study of chronic disabling occupational lumbar spinal disorder patients, including those with and without prior lumbar spinal surgeries. A sample of 126 chronic disabling occupational lumbar spinal disorder patients with prior work-related injuries entered an interdisciplinary functional restoration program and agreed to enroll in this study. Fifty-seven patients had undergone surgical decompression or discectomy (n=32) or lumbar fusion (n=25), and the rest had no history of prior injury-related spine surgery (n=69). At post-treatment, 116 patients were reevaluated, including those with prior decompressions or discectomies (n=30), lumbar fusions (n=21), and no surgery (n=65). A comparison group of 30 pain-free control subjects was tested with an identical assessment protocol, and compared with post-rehabilitation outcomes. Mean surface electromyography (SEMG) at maximum voluntary flexion; subject achievement of flexion-relaxation (SEMG≤3.5 μV); gross lumbar, true lumbar, and pelvic flexion ROM; and a pain visual analog scale self-report during forward bending task. Identical measures were obtained at pretreatment and post-treatment. Patients entered an interdisciplinary functional restoration program, including a quantitatively directed, medically supervised exercise process and a multimodal psychosocial disability management component. The functional restoration program was accompanied by a SEMG-assisted stretching training program, designed to teach relaxation of the lumbar musculature during end-range flexion

Transverse water relaxation in whole blood and erythrocytes at 3T, 7T, 9.4T, 11.7T and 16.4T; determination of intracellular hemoglobin and extracellular albumin relaxivities.

Science.gov (United States)

Grgac, Ksenija; Li, Wenbo; Huang, Alan; Qin, Qin; van Zijl, Peter C M

2017-05-01

Blood is a physiological substance with multiple water compartments, which contain water-binding proteins such as hemoglobin in erythrocytes and albumin in plasma. Knowing the water transverse (R 2 ) relaxation rates from these different blood compartments is a prerequisite for quantifying the blood oxygenation level-dependent (BOLD) effect. Here, we report the Carr-Purcell-Meiboom-Gill (CPMG) based transverse (R 2CPMG ) relaxation rates of water in bovine blood samples circulated in a perfusion system at physiological temperature in order to mimic blood perfusion in humans. R 2CPMG values of blood plasma, lysed packed erythrocytes, lysed plasma/erythrocyte mixtures, and whole blood at 3 T, 7 T, 9.4 T, 11.7 T and 16.4 T were measured as a function of hematocrit or hemoglobin concentration, oxygenation, and CPMG inter-echo spacing (τ cp ). R 2CPMG in lysed cells showed a small τ cp dependence, attributed to the water exchange rate between free and hemoglobin-bound water to be much faster than τ cp . This was contrary to the tangential dependence in whole blood, where a much slower exchange between cells and blood plasma applies. Whole blood data were fitted as a function of τ cp using a general tangential correlation time model applicable for exchange as well as diffusion contributions to R 2CPMG , and the intercept R 20blood at infinitely short τ cp was determined. The R 20blood values at different hematocrit and the R 2CPMG values of lysed erythrocyte/plasma mixtures at different hemoglobin concentration were used to determine the relaxivity of hemoglobin inside the erythrocyte (r 2Hb ) and albumin (r 2Alb ) in plasma. The r 2Hb values obtained from lysed erythrocytes and whole blood were comparable at full oxygenation. However, while r 2Hb determined from lysed cells showed a linear dependence on oxygenation, this dependence became quadratic in whole blood. This possibly suggests an additional relaxation effect inside intact cells, perhaps due to hemoglobin

A study of nuclear relaxation to the electron non-Zeeman system

International Nuclear Information System (INIS)

Honten, J. van.

1979-01-01

An examination of the nuclear spin-lattice relaxation mechanism in a series of diluted copper-caesium Tutton salt crystals, containing different percentages of D 2 O in the waters of hydration, is described. Results of relaxation measurements are presented and a strong angular dependence is observed. It is proved, however, that under most experimental conditions applied, the bottleneck in the relaxation path is not the cross-relaxation but the thermal contact between the proton Zeeman system and the electron dipole-dipole interaction system. Hence the proton spin-lattice relaxation measurements have enabled determination of the time constant of this thermal contact. The microscopic coupling process which provides thermal contact, is a simultaneous transition of two electron spins and one proton spin. This so-called three-spin transition is described and calculations presented. Double resonance experiments are performed, where the resonance signal of deuterium or caesium spins is saturated and the effect on the proton resonance signal observed. (C.F.)

Structure relaxation effect on superconductive properties of amorphous metallic ZrΛ9Λ0BΛ3SiΛ7 alloy

International Nuclear Information System (INIS)

Zolotukhin, I.V.; Zheleznyj, V.S.; Rudyj, S.D.; Fedorov, V.M.

1985-01-01

The effect of structural relaxation on electronand phonon spectra and electron-phonon interaction of Zr 90 B 3 Si 7 amorphous alloy is investigated. The specific electric conductivity rho 293 , superconducting transition temperature Tsub(c), critical magnetic field Bsub(c) (near Tsub(c)) and the Young modulus E 293 were measured. The Debye temperature THETA sub(D), electron state density on the Fermi surface N(O electron-phonon interaction constant lambda) mean square of a matrix element and the Hopfeld parameter were calculated. Experimental data show that Tsub(c) decreases during the structural relaxation of amorphous alloy in spite of increasing THETA sub(D) and N(O). However, the calculations show that during the structural relaxation the matrix element of the electron-phonon inte raction decreases with a simultaneous lambda decrease and an insignificant change in the Hopfeld parameter

Relaxation of helium levels excited by heavy ion impact: III.- Orientation by anisotropic relaxation of excited atoms in previously aligned states

International Nuclear Information System (INIS)

Chamoun, E.; Lombardi, M.; Carre, M.; Gaillard, M.L.

1977-01-01

In the last paper of this series devoted to relaxation phenomena in a low pressure cell of helium excited by an accelerated ion beam, experimental evidence is given for a new mechanism of transfer between alignment and orientation through anisotropic relaxation of initially aligned excited states. The theory predicting this effect is briefly outlined and then description is given of the exact experimental conditions to detect the circularly polarized component of the light emitted by the target excited in the 4 1 D level of He I by Na + impact [fr

Cutaneous Sensory Block Area, Muscle-Relaxing Effect, and Block Duration of the Transversus Abdominis Plane Block

DEFF Research Database (Denmark)

Støving, Kion; Rothe, Christian; Rosenstock, Charlotte V

2015-01-01

BACKGROUND AND OBJECTIVES: The transversus abdominis plane (TAP) block is a widely used nerve block. However, basic block characteristics are poorly described. The purpose of this study was to assess the cutaneous sensory block area, muscle-relaxing effect, and block duration. METHODS: Sixteen...... healthy volunteers were randomized to receive an ultrasound-guided unilateral TAP block with 20 mL 7.5 mg/mL ropivacaine and placebo on the contralateral side. Measurements were performed at baseline and 90 minutes after performing the block. Cutaneous sensory block area was mapped and separated...... into a medial and lateral part by a vertical line through the anterior superior iliac spine. We measured muscle thickness of the 3 lateral abdominal muscle layers with ultrasound in the relaxed state and during maximal voluntary muscle contraction. The volunteers reported the duration of the sensory block...

Effect of radiation and non-Maxwellian electron distribution on relaxation processes in an atmospheric cesium seeded argon plasma

International Nuclear Information System (INIS)

Borghi, C.A.; Veefkind, A.; Wetzer, J.M.

1982-03-01

A model, describing the time dependent behaviour of a noble gas MHD generator plasma, has been set up. With this model it is possible to calculate the relaxation for ionization or recombination as a response to a stepwise temperature development, once the initial and final conditions are given. In model radiative transitions and a deviation from Maxwellian electron distribution are included. Radiation causes an enhancement of both the ionization relaxation time and the recombination relaxation time. A non-Maxwellian electron distribution results in an increase of the relaxation time for an ionizing plasma because of an underpopulation of the high energy electrons. A decrease of the relaxation time for a recombining plasma is caused by an overpopulation of high energy electrons. The relaxation time is strongly dependent on the seed ratio and the temperature step. (Auth.)

GRAIN ALIGNMENT INDUCED BY RADIATIVE TORQUES: EFFECTS OF INTERNAL RELAXATION OF ENERGY AND COMPLEX RADIATION FIELD

International Nuclear Information System (INIS)

Hoang, Thiem; Lazarian, A.

2009-01-01

Earlier studies of grain alignment dealt mostly with interstellar grains that have strong internal relaxation of energy which aligns the grain axis of maximum moment of inertia (the axis of major inertia) with respect to the grain's angular momentum. In this paper, we study the alignment by radiative torques for large irregular grains, e.g., grains in accretion disks, for which internal relaxation is subdominant. We use both numerical calculations and the analytical model of a helical grain introduced by us earlier. We demonstrate that grains in such a regime exhibit more complex dynamics. In particular, if initially the grain axis of major inertia makes a small angle with angular momentum, then radiative torques can align the grain axis of major inertia with angular momentum, and both the axis of major inertia and angular momentum are aligned with the magnetic field when attractors with high angular momentum (high-J attractors) are available. For alignment without high-J attractors, beside the earlier studied attractors with low angular momentum (low-J attractors), there appear new low-J attractors. In addition, we also study the alignment of grains in the presence of strong internal relaxation, but induced not by a radiation beam as in earlier studies but instead induced by a complex radiation field that can be decomposed into dipole and quadrupole components. We found that in this situation the parameter space q max , for which high-J attractors exist in trajectory maps, is more extended, resulting in the higher degree of polarization expected. Our results are useful for modeling polarization arising from aligned dust grains in molecular clouds.

Thermal Annealing induced relaxation of compressive strain in porous GaN structures

KAUST Repository

Ben Slimane, Ahmed; Najar, Adel; Ng, Tien Khee; Ooi, Boon S.

2012-01-01

The effect of annealing on strain relaxation in porous GaN fabricated using electroless chemical etching is presented. The Raman shift of 1 cm-1 in phonon frequency of annealed porous GaN with respect to as-grown GaN corresponds to a relaxation

The effect of control of diabetes mellitus on plasma T4, T3, rT3 levels and half muscle relaxation period

International Nuclear Information System (INIS)

Ismail, A.A.; Hafiez, A.A.; Sayed, S.N.; Abbas, E.Z.; Halawa, F.A.; Youssef, M.M.

1984-01-01

25 diabetics of the maturity onset type who showed no clinical evidence of either peripheral neruropathy or diabetic amyotrophy were selected for this study. All patients were subjected to the following investigations: estimation of half muscle relaxation period of the quadriceps muscle knee-jerk, measurement of plasma levels of thyroxine (T 4 ), triiodothyronine (T 3 ) and reverse triiodothronine (rT 3 ), determination of fasting and two hours postprandial blood sugar levels. The quadriceps muscle relaxation period in uncontrolled diabetics was significantly longer than in normals. Control of diabetes by glibenclamide or gliclazide did not cause a significant change in muscle relaxation period. There was also no significant difference between the effects of the two drugs. (author)

Detection method of flexion relaxation phenomenon based on wavelets for patients with low back pain

Science.gov (United States)

Nougarou, François; Massicotte, Daniel; Descarreaux, Martin

2012-12-01

The flexion relaxation phenomenon (FRP) can be defined as a reduction or silence of myoelectric activity of the lumbar erector spinae muscle during full trunk flexion. It is typically absent in patients with chronic low back pain (LBP). Before any broad clinical utilization of this neuromuscular response can be made, effective, standardized, and accurate methods of identifying FRP limits are needed. However, this phenomenon is clearly more difficult to detect for LBP patients than for healthy patients. The main goal of this study is to develop an automated method based on wavelet transformation that would improve time point limits detection of surface electromyography signals of the FRP in case of LBP patients. Conventional visual identification and proposed automated methods of time point limits detection of relaxation phase were compared on experimental data using criteria of accuracy and repeatability based on physiological properties. The evaluation demonstrates that the use of wavelet transform (WT) yields better results than methods without wavelet decomposition. Furthermore, methods based on wavelet per packet transform are more effective than algorithms employing discrete WT. Compared to visual detection, in addition to demonstrating an obvious saving of time, the use of wavelet per packet transform improves the accuracy and repeatability in the detection of the FRP limits. These results clearly highlight the value of the proposed technique in identifying onset and offset of the flexion relaxation response in LBP subjects.

Stretched-exponential relaxation of the nonlinear dielectric effect in a critical binary solution

Science.gov (United States)

Rzoska, Sylwester J.; Górny, Michał; Zioło, Jerzy

1991-01-01

An experimental confirmation is given of the existence of a stretched-exponential relaxation of the form exp[-(t/τ)x] with x~=0.39 in a binary solution with an upper critical point. The nonlinear dielectric effect (NDE) method was used for this experiment. Results obtained are similar to those reported earlier by Piazza et al. [J. Opt. Soc. Am. B 3, 1642 (1986); Phys. Rev. B 38, 7223 (1988)] based on the Kerr-effect measurements in solutions with a lower critical point. Studies could be carried out in the immediate vicinity of the critical point, because the application of the NDE is not restricted by the appearance of the critical opalescence.

Effect of hypothyroidism on the nitrergic relaxant responses of corpus cavernosal smooth muscle in rabbits.

Science.gov (United States)

Sarac, Bulent; Yildirim, Mustafa K; Bagcivan, Ihsan; Kaya, Kemal; Kilicarslan, Hakan; Yildirim, Sahin

2006-01-01

The incidence of hormonal dysfunction as a cause of impotence remains controversial. However, several recent studies have reported evidence of hormonal abnormalities in 25-35% of impotent men. Hypothyroidism has been reported to occur in 6% of impotent men. In the present study, we examined nitrergic responses in hypothyroidism in rabbit corpus cavernosum and compared them with controls. Carbachol-induced relaxation responses and electrical field stimulation (EFS)-induced frequency-dependent relaxations decreased significantly in hypothyroid rabbits. Papaverine and sodium nitroprusside (SNP)-induced relaxation responses did not change significantly in hypothyroid rabbits. The contraction responses of phenylephrine and EFS-induced frequency-dependent contractions were significantly decreased in the hypothyroid group. We can speculate that the reduction of relaxant responses to EFS and carbachol in hypothyroid rabbits can depend on a decreased release of nitric oxide (NO) from nitrergic nerves and endothelium or a reduction of muscarinic receptor density. Also, decreases in contraction responses may depend on diminished adrenoceptor density.

Mitigating IPMC back relaxation through feedforward and feedback control of patterned electrodes

International Nuclear Information System (INIS)

Fleming, Maxwell J; Leang, Kam K; Kim, Kwang J

2012-01-01

With low driving voltage ( < 5 V) and the ability to be operated in aqueous environments, ionic polymer–metal composite (IPMC) materials are quickly gaining attention for use in many applications including soft bio-inspired actuators and sensors. There are, however, drawbacks to IPMC actuators, including the ‘back relaxation’ effect. Specifically, when subjected to an excessively slow input, the IPMC actuator will slowly relax back toward its original position. There is debate over the physical mechanism of back relaxation, although one prevalent theory describes an initial current, caused by the electrostatic forces of the charging electrodes, which drives water molecules across the ion exchange membrane and deforms the IPMC. Once the electrodes are fully charged, however, the dominant element of the motion is the osmotic pressure, driving the water molecules back to equilibrium, thus causing back relaxation. A new method to mitigate back relaxation is proposed, taking advantage of controlled activation of patterned (sectored) electrodes on the IPMC. By actuating sectors in opposing directions, back relaxation can be effectively canceled out. An integrated feedforward and feedback controller is employed based on this concept, and is shown to minimize back relaxation, while reducing the input voltage required, as compared to the case of the non-sectored IPMC. Experimental results show nearly an order of magnitude reduction in the tracking error compared to the uncompensated case, and that the IPMC’s position can be maintained over a period of 60 and 1200 s with minimal evidence of back relaxation. (paper)

Nuclear magnetic relaxation by the dipolar EMOR mechanism: Multi-spin systems

Science.gov (United States)

Chang, Zhiwei; Halle, Bertil

2017-08-01

In aqueous systems with immobilized macromolecules, including biological tissues, the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. Starting from the stochastic Liouville equation, we have previously developed a rigorous EMOR relaxation theory for dipole-coupled two-spin and three-spin systems. Here, we extend the stochastic Liouville theory to four-spin systems and use these exact results as a guide for constructing an approximate multi-spin theory, valid for spin systems of arbitrary size. This so-called generalized stochastic Redfield equation (GSRE) theory includes the effects of longitudinal-transverse cross-mode relaxation, which gives rise to an inverted step in the relaxation dispersion profile, and coherent spin mode transfer among solid-like spins, which may be regarded as generalized spin diffusion. The GSRE theory is compared to an existing theory, based on the extended Solomon equations, which does not incorporate these phenomena. Relaxation dispersion profiles are computed from the GSRE theory for systems of up to 16 protons, taken from protein crystal structures. These profiles span the range from the motional narrowing limit, where the coherent mode transfer plays a major role, to the ultra-slow motion limit, where the zero-field rate is closely related to the strong-collision limit of the dipolar relaxation rate. Although a quantitative analysis of experimental data is beyond the scope of this work, it is clear from the magnitude of the predicted relaxation rate and the shape of the relaxation dispersion profile that the dipolar EMOR mechanism is the principal cause of water-1H low-field longitudinal relaxation in aqueous systems of immobilized macromolecules, including soft biological tissues. The relaxation theory developed here therefore provides a basis for molecular-level interpretation of endogenous soft

r1 and r2 Relaxivities of Dendrons Based on a OEG-DTPA Architecture: Effect of Gd3+ Placement and Dendron Functionalization

International Nuclear Information System (INIS)

Fransen, P.; Simon-Gracia, L.; Albericio, F.; Fransen, P.; Pulido, D.; Simon-Gracia, L.; Candiata, A.P.; Arus, C.; Albericio, F.; Royo, M.; Pulido, D.; Royo, M.; Candiata, A.P.; Arus, C.; Candiata, A.P.; Albericio, F.; Candiata, A.P.

2015-01-01

In magnetic resonance imaging, contrast agents are employed to enhance the signal intensity. However, current commercial contrast agents are hindered by a low relaxivity constant. Dendrimers can be employed to create higher molecular weight contrast agents which have an increased relaxivity due to a lower molecular rotation. In this study, dendrimers containing DTPA derivatives as cores and/or branching units were used to chelate gadolinium ions. Locating the gadolinium ions inside the dendrimers results in higher relaxivity constants, possibly because the paramagnetic center is closer to the rotational axis of the macromolecule. The highest gain in relaxivity was produced by decorating the dendron surface with peptide sequences, which could be explained by the presence of more second-sphere water molecules attracted by the peptides. These findings could contribute to the development of more effective contrast agents, either by placing the paramagnetic gadolinium ion in a strategic position or through functionalization of the dendron surface.

r1 and r2 Relaxivities of Dendrons Based on a OEG-DTPA Architecture: Effect of Gd3+ Placement and Dendron Functionalization

Directory of Open Access Journals (Sweden)

Peter Fransen

2015-01-01

Full Text Available In magnetic resonance imaging, contrast agents are employed to enhance the signal intensity. However, current commercial contrast agents are hindered by a low relaxivity constant. Dendrimers can be employed to create higher molecular weight contrast agents which have an increased relaxivity due to a lower molecular rotation. In this study, dendrimers containing DTPA derivatives as cores and/or branching units were used to chelate gadolinium ions. Locating the gadolinium ions inside the dendrimers results in higher relaxivity constants, possibly because the paramagnetic center is closer to the rotational axis of the macromolecule. The highest gain in relaxivity was produced by decorating the dendron surface with peptide sequences, which could be explained by the presence of more second-sphere water molecules attracted by the peptides. These findings could contribute to the development of more effective contrast agents, either by placing the paramagnetic gadolinium ion in a strategic position or through functionalization of the dendron surface.

A hierarchy of functionally important relaxations within myoglobin based on solvent effects, mutations and kinetic model.

Science.gov (United States)

Dantsker, David; Samuni, Uri; Friedman, Joel M; Agmon, Noam

2005-06-01

Geminate CO rebinding in myoglobin is studied for two viscous solvents, trehalose and sol-gel (bathed in 100% glycerol) at several temperatures. Mutations in key distal hemepocket residues are used to eliminate or enhance specific relaxation modes. The time-resolved data are analyzed with a modified Agmon-Hopfield model which is capable of providing excellent fits in cases where a single relaxation mode is dominant. Using this approach, we determine the relaxation rate constants of specific functionally important modes, obtaining also their Arrhenius activation energies. We find a hierarchy of distal pocket modes controlling the rebinding kinetics. The "heme access mode" (HAM) is responsible for the major slow-down in rebinding. It is a solvent-coupled cooperative mode which restricts ligand return from the xenon cavities. Bulky side-chains, like those His64 and Trp29 (in the L29W mutant), operate like overdamped pendulums which move over and block the binding site. They may be either unslaved (His64) or moderately slaved (Trp29) to the solvent. Small side-chain relaxations, most notably of leucines, are revealed in some mutants (V68L, V68A). They are conjectured to facilitate inter-cavity ligand motion. When all relaxations are arrested (H64L in trehalose), we observe pure inhomogeneous kinetics with no temperature dependence, suggesting that proximal relaxation is not a factor on the investigated timescale.

Can relaxation interventions reduce anxiety in patients receiving radiotherapy? outcomes and study validity

International Nuclear Information System (INIS)