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Sample records for relaxation matrix procedure

NMR structural refinement of an extrahelical adenosine tridecamer d(CGCAGAATTCGCG)2 via a hybrid relaxation matrix procedure

International Nuclear Information System (INIS)

Nikonowicz, E.P.; Meadows, R.P.; Gorenstein, D.G.

1990-01-01

Until very recently interproton distances from NOESY experiments have been derived solely from the two-spin approximation method. Unfortunately, even at short mixing times, there is a significant error in many of these distances. A complete relaxation matrix approach employing a matrix eigenvalue/eigenvector solution to the Bloch equations avoids the approximation of the two-spin method. The authors calculated the structure of an extrahelical adenosine tridecamer oligodeoxyribonucleotide duplex, d-(CGCAGAATTCGCG) 2 , by an iterative refinement approach using a hybrid relaxation matrix method combined with restrained molecular dynamics calculations. Distances from the 2D NOESY spectra have been calculated from the relaxation rate matrix which has been evaluated from a hybrid NOESY volume matrix comprising elements from the experiment and those calculated from an initial structure. The hybrid matrix derived distances have then been used in a restrained molecular dynamics procedure to obtain a new structure that better approximates the NOESY spectra. The resulting partially refined structure is then used to calculate an improved theoretical NOESY volume matrix which is once again merged with the experimental matrix until refinement is complete. Although the crystal structure of the tridecamer clearly shows the extrahelical adenosine looped out way from the duplex, the NOESY distance restrained hybrid matrix/molecular dynamics structural refinement establishes that the extrahelical adenosine stacks into the duplex
Two-dimensional 1H and 31P NMR spectra and restrained molecular dynamics structure of an oligodeoxyribonucleotide duplex refined via a hybrid relaxation matrix procedure

International Nuclear Information System (INIS)

Powers, R.; Jones, C.R.; Gorenstein, D.G.

1990-01-01

Assignment of the 1H and 31P resonances of a decamer DNA duplex, d(CGCTTAAGCG)2 was determined by two-dimensional COSY, NOESY and 1H-31P Pure Absorption phase Constant time (PAC) heteronuclear correlation spectroscopy. The solution structure of the decamer was calculated by an iterative hybrid relaxation matrix method combined with NOESY-distance restrained molecular dynamics. The distances from the 2D NOESY spectra were calculated from the relaxation rate matrix which were evaluated from a hybrid NOESY volume matrix comprising elements from the experiment and those calculated from an initial structure. The hybrid matrix-derived distances were then used in a restrained molecular dynamics procedure to obtain a new structure that better approximates the NOESY spectra. The resulting partially refined structure was then used to calculate an improved theoretical NOESY volume matrix which is once again merged with the experimental matrix until refinement is complete. JH3'-P coupling constants for each of the phosphates of the decamer were obtained from 1H-31P J-resolved selective proton flip 2D spectra. By using a modified Karplus relationship the C4'-C3'-O3'-P torsional angles were obtained. Comparison of the 31P chemical shifts and JH3'-P coupling constants of this sequence has allowed a greater insight into the various factors responsible for 31P chemical shift variations in oligonucleotides. It also provides an important probe of the sequence-dependent structural variation of the deoxyribose phosphate backbone of DNA in solution. These correlations are consistent with the hypothesis that changes in local helical structure perturb the deoxyribose phosphate backbone. The variation of the 31P chemical shift, and the degree of this variation from one base step to the next is proposed as a potential probe of local helical conformation within the DNA double helix
Vibrational relaxation and energy transfer of matrix isolated HCl and DCl

Energy Technology Data Exchange (ETDEWEB)

Wiesenfeld, J.M.

1977-12-01

Vibrational kinetic and spectroscopic studies have been performed on matrix-isolated HCl and DCl between 9 and 20 K. Vibrational relaxation rates for v = 2 and v = 1 were measured by a tunable infrared laser-induced, time-resolved fluorescence technique. In an Ar matrix, vibrational decay times are faster than radiative and it is found that HCl relaxes about 35 times more rapidly than CCl, in spite of the fact that HCl must transfer more energy to the lattice than DCl. This result is explained by postulating that the rate-determining step for vibrational relaxation produces a highly rotationally excited guest in a V yield R step; rotational relaxation into lattice phonons follows rapidly. HCl v = 1, but not v = 2, excitation rapidly diffuses through the sample by a resonant dipole-dipole vibrational energy transfer process. Molecular complexes, and in particular the HCl dimer, relax too rapidly for direct observation, less than or approximately 1 ..mu..s, and act as energy sinks in the energy diffusion process. The temperature dependence for all these processes is weak--less than a factor of two between 9 and 20 K. Vibrational relaxation of HCl in N/sub 2/ and O/sub 2/ matrices is unobservable, presumably due to rapid V yield V transfer to the host. A V yield R binary collision model for relaxation in solids is successful in explaining the HCl(DCl)/Ar results as well as results of other experimenters. The model considers relaxation to be the result of ''collisions'' due to molecular motion in quantized lattice normal modes--gas phase potential parameters can fit the matrix kinetic data.
Vibrational relaxation and energy transfer of matrix isolated HCl and DCl

International Nuclear Information System (INIS)

Wiesenfeld, J.M.

1977-12-01

Vibrational kinetic and spectroscopic studies have been performed on matrix-isolated HCl and DCl between 9 and 20 K. Vibrational relaxation rates for v = 2 and v = 1 were measured by a tunable infrared laser-induced, time-resolved fluorescence technique. In an Ar matrix, vibrational decay times are faster than radiative and it is found that HCl relaxes about 35 times more rapidly than CCl, in spite of the fact that HCl must transfer more energy to the lattice than DCl. This result is explained by postulating that the rate-determining step for vibrational relaxation produces a highly rotationally excited guest in a V yield R step; rotational relaxation into lattice phonons follows rapidly. HCl v = 1, but not v = 2, excitation rapidly diffuses through the sample by a resonant dipole-dipole vibrational energy transfer process. Molecular complexes, and in particular the HCl dimer, relax too rapidly for direct observation, less than or approximately 1 μs, and act as energy sinks in the energy diffusion process. The temperature dependence for all these processes is weak--less than a factor of two between 9 and 20 K. Vibrational relaxation of HCl in N 2 and O 2 matrices is unobservable, presumably due to rapid V yield V transfer to the host. A V yield R binary collision model for relaxation in solids is successful in explaining the HCl(DCl)/Ar results as well as results of other experimenters. The model considers relaxation to be the result of ''collisions'' due to molecular motion in quantized lattice normal modes--gas phase potential parameters can fit the matrix kinetic data
Efficient and robust relaxation procedures for multi-component mixtures including phase transition

International Nuclear Information System (INIS)

Han, Ee; Hantke, Maren; Müller, Siegfried

2017-01-01

We consider a thermodynamic consistent multi-component model in multi-dimensions that is a generalization of the classical two-phase flow model of Baer and Nunziato. The exchange of mass, momentum and energy between the phases is described by additional source terms. Typically these terms are handled by relaxation procedures. Available relaxation procedures suffer from efficiency and robustness resulting in very costly computations that in general only allow for one-dimensional computations. Therefore we focus on the development of new efficient and robust numerical methods for relaxation processes. We derive exact procedures to determine mechanical and thermal equilibrium states. Further we introduce a novel iterative method to treat the mass transfer for a three component mixture. All new procedures can be extended to an arbitrary number of inert ideal gases. We prove existence, uniqueness and physical admissibility of the resulting states and convergence of our new procedures. Efficiency and robustness of the procedures are verified by means of numerical computations in one and two space dimensions. - Highlights: • We develop novel relaxation procedures for a generalized, thermodynamically consistent Baer–Nunziato type model. • Exact procedures for mechanical and thermal relaxation procedures avoid artificial parameters. • Existence, uniqueness and physical admissibility of the equilibrium states are proven for special mixtures. • A novel iterative method for mass transfer is introduced for a three component mixture providing a unique and admissible equilibrium state.
Matrix-assisted relaxation in Fe(phen)2(NCS)2 spin-crossover microparticles, experimental and theoretical investigations

International Nuclear Information System (INIS)

Enachescu, Cristian; Stancu, Alexandru; Tanasa, Radu; Tissot, Antoine; Laisney, Jérôme; Boillot, Marie-Laure

2016-01-01

In this study, we present the influence of the embedding matrix on the relaxation of Fe(phen) 2 (NCS) 2 (phen = 1,10-phenanthroline) spin-transition microparticles as revealed by experiments and provide an explanation within the framework of an elastic model based on a Monte-Carlo method. Experiments show that the shape of the high-spin → low-spin relaxation curves is drastically changed when the particles are dispersed in glycerol. This effect was considered in the model by means of interactions between the microparticles and the matrix. A faster start of the relaxation for microparticles embedded in glycerol is due to an initial positive local pressure acting on the edge spin-crossover molecules from the matrix side. This local pressure diminishes and eventually becomes negative during relaxation, as an effect of the decrease of the volume of spin-crossover microparticles from high-spin to low-spin.
Vibrational relaxation of matrix-isolated CH3F and HCl

International Nuclear Information System (INIS)

Young, L.

1981-08-01

Kinetic and spectroscopic studies have been performed on CH 3 F and HCl as a function of host matrix and temperature. Temporally and spectrally resolved infrared fluorescence was used to monitor the populations of both the initially excited state and the lower lying levels which participate in the relaxation process. For CH 3 F, relaxation from any of the levels near 3.5 μ, i.e. the CH stretching fundamentals or bend overtones, occurs via rapid ( 3 with subsequent relaxation of the ν 3 (CF stretch) manifold. Lifetimes of 2ν 3 and ν 3 were determined through overtone, ΔV = 2, and fundamental fluorescence. These lifetimes show a dramatic dependence on host lattice, an increase of two orders of magnitude in going from Xe and Ar matrices. Lifetimes depend only weakly on temperature. The relaxation of 2ν 3 and ν 3 is consistent with a model in which production of a highly rotationally excited guest via collisions with the repulsive wall of the host is the rate limiting step. For HCl, lifetimes of v = 1,2,3 have been determined. In all hosts, the relaxation is non-radiative. For a given vibrational state, v, the relaxation rate increases in the series k(Ar) < k(Kr) < k(Xe). The dependence of the relaxation rate; on v is superlinear in all matrices, the deviation from linearity increasng in the order Ar < Kr < Xe. The relaxation rates become more strongly temperature dependent with increasing vibrational excitation. The results are consistent with a mechanism in which complex formation introduces the anisotropy necessary to induce a near resonant V → R transition in the rate limiting step
Matrix-assisted relaxation in Fe(phen){sub 2}(NCS){sub 2} spin-crossover microparticles, experimental and theoretical investigations

Energy Technology Data Exchange (ETDEWEB)

Enachescu, Cristian, E-mail: cristian.enachescu@uaic.ro; Stancu, Alexandru [Faculty of Physics, “Alexandru Ioan Cuza” University, 700506 Iasi (Romania); Tanasa, Radu [Faculty of Physics, “Alexandru Ioan Cuza” University, 700506 Iasi (Romania); Department of Engineering, University of Cambridge, CB2 1PZ Cambridge (United Kingdom); Tissot, Antoine [Institut de Chimie Moléculaire et des Matériaux d' Orsay, Université Paris Sud, Université Paris-Saclay, CNRS, 91405 Orsay (France); Institut Lavoisier de Versailles, UMR 8180, CNRS, Université de Versailles-Saint Quentin en Yvelines, 78035 Versailles (France); Laisney, Jérôme; Boillot, Marie-Laure, E-mail: marie-laure.boillot@u-psud.fr [Institut de Chimie Moléculaire et des Matériaux d' Orsay, Université Paris Sud, Université Paris-Saclay, CNRS, 91405 Orsay (France)

2016-07-18

In this study, we present the influence of the embedding matrix on the relaxation of Fe(phen){sub 2}(NCS){sub 2} (phen = 1,10-phenanthroline) spin-transition microparticles as revealed by experiments and provide an explanation within the framework of an elastic model based on a Monte-Carlo method. Experiments show that the shape of the high-spin → low-spin relaxation curves is drastically changed when the particles are dispersed in glycerol. This effect was considered in the model by means of interactions between the microparticles and the matrix. A faster start of the relaxation for microparticles embedded in glycerol is due to an initial positive local pressure acting on the edge spin-crossover molecules from the matrix side. This local pressure diminishes and eventually becomes negative during relaxation, as an effect of the decrease of the volume of spin-crossover microparticles from high-spin to low-spin.
Comparison of transition-matrix sampling procedures

DEFF Research Database (Denmark)

Yevick, D.; Reimer, M.; Tromborg, Bjarne

2009-01-01

We compare the accuracy of the multicanonical procedure with that of transition-matrix models of static and dynamic communication system properties incorporating different acceptance rules. We find that for appropriate ranges of the underlying numerical parameters, algorithmically simple yet high...... accurate procedures can be employed in place of the standard multicanonical sampling algorithm....
Anomalous NMR Relaxation in Cartilage Matrix Components and Native Cartilage: Fractional-Order Models

Science.gov (United States)

Magin, Richard L.; Li, Weiguo; Velasco, M. Pilar; Trujillo, Juan; Reiter, David A.; Morgenstern, Ashley; Spencer, Richard G.

2011-01-01

We present a fractional-order extension of the Bloch equations to describe anomalous NMR relaxation phenomena (T1 and T2). The model has solutions in the form of Mittag-Leffler and stretched exponential functions that generalize conventional exponential relaxation. Such functions have been shown by others to be useful for describing dielectric and viscoelastic relaxation in complex, heterogeneous materials. Here, we apply these fractional-order T1 and T2 relaxation models to experiments performed at 9.4 and 11.7 Tesla on type I collagen gels, chondroitin sulfate mixtures, and to bovine nasal cartilage (BNC), a largely isotropic and homogeneous form of cartilage. The results show that the fractional-order analysis captures important features of NMR relaxation that are typically described by multi-exponential decay models. We find that the T2 relaxation of BNC can be described in a unique way by a single fractional-order parameter (α), in contrast to the lack of uniqueness of multi-exponential fits in the realistic setting of a finite signal-to-noise ratio. No anomalous behavior of T1 was observed in BNC. In the single-component gels, for T2 measurements, increasing the concentration of the largest components of cartilage matrix, collagen and chondroitin sulfate, results in a decrease in α, reflecting a more restricted aqueous environment. The quality of the curve fits obtained using Mittag-Leffler and stretched exponential functions are in some cases superior to those obtained using mono- and bi-exponential models. In both gels and BNC, α appears to account for microstructural complexity in the setting of an altered distribution of relaxation times. This work suggests the utility of fractional-order models to describe T2 NMR relaxation processes in biological tissues. PMID:21498095
Two Procedures for Relaxation as Self-Control in the Treatment of Communication Apprehension

Science.gov (United States)

Deffenbacher, Jerry L.; Payne, Dennis M.

1977-01-01

An in vivo procedure for relaxation as self-control and a procedure for self-control modification of desensitization were compared to a no-treatment control. Results showed modified desensitization, compared to the control, significantly decreased communication anxiety and fear of negative evaluation and significantly increased assertiveness.…
NMR structural refinement of a tandem G·A mismatched decamer d(CCAAGATTGG)2 via the hybrid matrix procedure

International Nuclear Information System (INIS)

Nikonowicz, E.P.; Meadows, R.P.; Fagan, P.; Gorenstein, D.G.

1991-01-01

A complete relaxation matrix approach employing a matrix eigenvalue/eigenvector solution to the Bloch equations is used to evaluate the NMR solution structure of a tandemly positioned G·A double mismatch decamer oligodeoxyribonucleotide duplex, d(CCAAGATTGG) 2 . An iterative refinement method using a hybrid relaxation matrix combined with restrained molecular dynamics calculations is shown to provide structures having good agreement with the experimentally derived structures. Distances incorporated into the MD simulations have been calculated from the relaxation rate matrix evaluated from a hybrid NOESY volume matrix whose elements are obtained from the merging of experimental and calculated NOESY intensities. Starting from both A- and B-DNA and mismatch syn and anti models, it is possible to calculate structures that are in good atomic RMS agreement with each other ( 3.6 angstrom). Importantly, the hybrid matrix derived structures are in excellent agreement with the experimental solution conformation as determined by comparison of the 200-ms simulated and experimental NOESY spectra, while the crystallographic data provide spectra that are grossly different
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)
Use of the contingency matrix in the TRACK-MATCH procedure for two projections

International Nuclear Information System (INIS)

Baginyan, S.A.; Moroz, V.I.

1985-01-01

When analysing the work of geometrical reconstruction programs it is noted that if the TRACK-MATCH procedure is successful, it garantes the event measurement correctness. This serves as a base for application of the TRACK-MATCH procedure as a test for event mask measurements. Such use of the procedure does not require point-to-point correspondence between track images in different projections. It is sufficient to establish that the TRACK-MATCH procedure admits a solusion. It is shown that the problem of point-to-point correspondence between track images in different projections is reduced to conting matrix analysis. It is stated that if the determinant of the contingency matrix is not equal to zero it is sufficient for the TRACK-MATCH procedure to be solved
Regularized Label Relaxation Linear Regression.

Science.gov (United States)

Fang, Xiaozhao; Xu, Yong; Li, Xuelong; Lai, Zhihui; Wong, Wai Keung; Fang, Bingwu

2018-04-01

Linear regression (LR) and some of its variants have been widely used for classification problems. Most of these methods assume that during the learning phase, the training samples can be exactly transformed into a strict binary label matrix, which has too little freedom to fit the labels adequately. To address this problem, in this paper, we propose a novel regularized label relaxation LR method, which has the following notable characteristics. First, the proposed method relaxes the strict binary label matrix into a slack variable matrix by introducing a nonnegative label relaxation matrix into LR, which provides more freedom to fit the labels and simultaneously enlarges the margins between different classes as much as possible. Second, the proposed method constructs the class compactness graph based on manifold learning and uses it as the regularization item to avoid the problem of overfitting. The class compactness graph is used to ensure that the samples sharing the same labels can be kept close after they are transformed. Two different algorithms, which are, respectively, based on -norm and -norm loss functions are devised. These two algorithms have compact closed-form solutions in each iteration so that they are easily implemented. Extensive experiments show that these two algorithms outperform the state-of-the-art algorithms in terms of the classification accuracy and running time.
IRMA iterative relaxation matrix approach for NMR structure determination application to DNA fragments

International Nuclear Information System (INIS)

Koning, M.M.G.

1990-01-01

The subject of this thesis is the structure determination of DNA molecules in solution with the use of NMR. For this purpose a new relaxation matrix approach is introduced. The emphasis is on the interpretation of nuclear Overhauser effects (NOEs) in terms of proton-proton distances and related three dimensional structures. The DNA molecules studied are obligonucleotides, unmodifief as well as modified molecules bu UV radiation. From comparison with unmodified molecules it turned out that UV irradiation scarcely influences the helical structure of the DNA string. At one place of the string a nucleotide is rotated towards the high-ANTI conformation which results in a slight unwinding of the DNA string but sufficient for blocking of the normal reading of genetic information. (H.W.). 456 refs.; 50 figs.; 30 tabs
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.
The Feasibility of Using the BrightHearts Biofeedback-Assisted Relaxation Application for the Management of Pediatric Procedural Pain: A Pilot Study.

Science.gov (United States)

Burton, Karen L O; Morrow, Angela M; Beswick, Brooke V; Khut, George P

2018-04-17

The objective of this pilot study was to assess the acceptability and feasibility of using BrightHearts, a biofeedback-assisted relaxation application (app), in children undergoing painful procedures. Thirty children 7 to 18 years of age undergoing a medical procedure (peripheral blood collection, botulinum toxin injection, or intravenous cannula insertion) participated. Participants used BrightHearts, a heart rate-controlled biofeedback-assisted relaxation training app delivered via an iPad with heart rate measured through a pulse oximeter worn on the ear or thumb. Feasibility was assessed through observations and patient, parent/carer, and healthcare professional feedback. Patient, parent/carer, and healthcare professional satisfaction with BrightHearts was rated using investigator-developed surveys. Eighty-three percent of child participants reported that they found BrightHearts helpful during the procedure and that they would use BrightHearts again. All parents and 96% of healthcare professionals indicated they would use BrightHearts again. Sixty-four percent of healthcare providers perceived that BrightHearts assisted with the ease of performing the procedure. Qualitative analyses found 2 themes: (1) BrightHearts calms through providing distraction and biofeedback and (2) the impact of BrightHearts on the procedure. This pilot study demonstrates the feasibility of using biofeedback-assisted relaxation delivered via the BrightHearts app in children undergoing peripheral blood collection and cannulation. Future studies are required to evaluate BrightHearts' efficacy in reducing pain and anxiety during painful procedures and distinguish the effects of a biofeedback-mediated app from distraction. © 2018 World Institute of Pain.
A Matrix Splitting Method for Composite Function Minimization

KAUST Repository

Yuan, Ganzhao

2016-12-07

Composite function minimization captures a wide spectrum of applications in both computer vision and machine learning. It includes bound constrained optimization and cardinality regularized optimization as special cases. This paper proposes and analyzes a new Matrix Splitting Method (MSM) for minimizing composite functions. It can be viewed as a generalization of the classical Gauss-Seidel method and the Successive Over-Relaxation method for solving linear systems in the literature. Incorporating a new Gaussian elimination procedure, the matrix splitting method achieves state-of-the-art performance. For convex problems, we establish the global convergence, convergence rate, and iteration complexity of MSM, while for non-convex problems, we prove its global convergence. Finally, we validate the performance of our matrix splitting method on two particular applications: nonnegative matrix factorization and cardinality regularized sparse coding. Extensive experiments show that our method outperforms existing composite function minimization techniques in term of both efficiency and efficacy.
A Matrix Splitting Method for Composite Function Minimization

KAUST Repository

Yuan, Ganzhao; Zheng, Wei-Shi; Ghanem, Bernard

2016-01-01

Composite function minimization captures a wide spectrum of applications in both computer vision and machine learning. It includes bound constrained optimization and cardinality regularized optimization as special cases. This paper proposes and analyzes a new Matrix Splitting Method (MSM) for minimizing composite functions. It can be viewed as a generalization of the classical Gauss-Seidel method and the Successive Over-Relaxation method for solving linear systems in the literature. Incorporating a new Gaussian elimination procedure, the matrix splitting method achieves state-of-the-art performance. For convex problems, we establish the global convergence, convergence rate, and iteration complexity of MSM, while for non-convex problems, we prove its global convergence. Finally, we validate the performance of our matrix splitting method on two particular applications: nonnegative matrix factorization and cardinality regularized sparse coding. Extensive experiments show that our method outperforms existing composite function minimization techniques in term of both efficiency and efficacy.

A random matrix model of relaxation

International Nuclear Information System (INIS)

Lebowitz, J L; Pastur, L

2004-01-01

We consider a two-level system, S 2 , coupled to a general n level system, S n , via a random matrix. We derive an integral representation for the mean reduced density matrix ρ(t) of S 2 in the limit n → ∞, and we identify a model of S n which possesses some of the properties expected for macroscopic thermal reservoirs. In particular, it yields the Gibbs form for ρ(∞). We also consider an analog of the van Hove limit and obtain a master equation (Markov dynamics) for the evolution of ρ(t) on an appropriate time scale
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.
Transport and relaxation properties of superfluid 3He. I. Kinetic equation and Bogoliubov quasiparticle relaxation rate

International Nuclear Information System (INIS)

Einzel, D.; Woelfle, P.

1978-01-01

The kinetic equation for Bogoliubov quasiparticles for both the A and B phases of superfluid 3 He is derived from the general matrix kinetic equation. A condensed expression for the exact spin-symmetric collision integral is given. The quasiparticle relaxation rate is calculated for the BW state using the s--p approximation for the quasiparticle scattering amplitude. By using the results for the quasiparticle relaxation rate, the mean free path of Bogoliubov quasiparticles is calculated for all temperatures
BREATHING EXERCISE RELAXATION INCREASE PHSYCOLOGICAL RESPONSE PRESCHOOL CHILDREN

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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.
Creep and stress relaxation induced by interface diffusion in metal matrix composites

Science.gov (United States)

Li, Yinfeng; Li, Zhonghua

2013-03-01

An analytical solution is developed to predict the creep rate induced by interface diffusion in unidirectional fiber-reinforced and particle reinforced composites. The driving force for the interface diffusion is the normal stress acting on the interface, which is obtained from rigorous Eshelby inclusion theory. The closed-form solution is an explicit function of the applied stress, volume fraction and radius of the fiber, as well as the modulus ratio between the fiber and the matrix. It is interesting that the solution is formally similar to that of Coble creep in polycrystalline materials. For the application of the present solution in the realistic composites, the scale effect is taken into account by finite element analysis based on a unit cell. Based on the solution, a closed-form solution is also given as a description of stress relaxation induced by interfacial diffusion under constant strain. In addition, the analytical solution for the interface stress presented in this study gives some insight into the relationship between the interface diffusion and interface slip. This work was supported by the financial support from the Nature Science Foundation of China (No. 10932007), the National Basic Research Program of China (No. 2010CB631003/5), and the Doctoral Program of Higher Education of China (No. 20100073110006).
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
The effects of progressive muscular relaxation as a nursing procedure used for those who suffer from stress due to multiple sclerosis

Directory of Open Access Journals (Sweden)

Paolla Gabrielle Nascimento Novais

Full Text Available ABSTRACT Objective: to evaluate the effect of progressive muscle relaxation as a nursing procedure on the levels of stress for sufferers of multiple sclerosis. Method: random clinical trials conducted at the Neurology outpatients unit at a University Hospital. The sample consisted of 40 patients who were being monitored as outpatients (20 in a control group and 20 in an experimental group. The Progressive Muscle Relaxation technique was used. The control variables were collected through interviews that were recorded on forms and on the Perceived Stress Scale that we used. Five meetings were held every fortnight covering a period of eight weeks. The experimental group was advised to carry out daily progressive muscle relaxation activities. After eight weeks of these activities, they were evaluated again to measure their levels of stress. In order to analyze the data used, the software package Statistics for Social Sciences version 19.0 was used. Results: the application of the t test showed a significant reduction in the Perceived Stress Scale scores in the experimental group (p<0.001, which in turn proved that there was a reduction in the levels of stress after the application of the relaxation practic-es. Conclusion: the progressive muscle relaxation activities contributed to the reduction in stress levels for multiple sclerosis suffers and thus can be used in nursing for patients. Clinical Trials Identifier: NCT 02673827.
Nuclear magnetic relaxation of methyl group in liquids

International Nuclear Information System (INIS)

Blicharska, B.

1986-01-01

The theoretical description of the relaxation process of methyl group in liquids and some results of the measurements of relaxation function and relaxation times for cryoprotective solutions are presented. Starting from the application of the operator formalism the general equation for spin operators e.g. components of the nuclear spin and magnetization is founded. Next, the spin Hamiltonian is presented as contraction of the symmetry adapted spherical tensors as well as the correlation functions and spectral densities. On the basis of extended and modified Woessner model of motion the correlation functions and spectral densities are calculated for methyl group in liquids. Using these functions the relaxation matrix elements, the spin-spin and spin-lattice relaxation times can be expressed. The prediction of the theory agrees with author's previous experiments on cryoprotective solutions. The observed dependence on temperature, frequency and isotopic dilution in methanol-water, methanol-dimethyl sulfoxide (DMSO) and DMSO-water solutions is in a satisfactory agreement with theoretical equations. 34 refs. (author)
Complete relaxation and conformational exchange matrix (CORCEMA) analysis of intermolecular saturation transfer effects in reversibly forming ligand-receptor complexes.

Science.gov (United States)

Jayalakshmi, V; Krishna, N Rama

2002-03-01

A couple of recent applications of intermolecular NOE (INOE) experiments as applied to biomolecular systems involve the (i) saturation transfer difference NMR (STD-NMR) method and (ii) the intermolecular cross-saturation NMR (ICS-NMR) experiment. STD-NMR is a promising tool for rapid screening of a large library of compounds to identify bioactive ligands binding to a target protein. Additionally, it is also useful in mapping the binding epitopes presented by a bioactive ligand to its target protein. In this latter application, the STD-NMR technique is essentially similar to the ICS-NMR experiment, which is used to map protein-protein or protein-nucleic acid contact surfaces in complexes. In this work, we present a complete relaxation and conformational exchange matrix (CORCEMA) theory (H. N. B. Moseley et al., J. Magn. Reson. B 108, 243-261 (1995)) applicable for these two closely related experiments. As in our previous work, we show that when exchange is fast on the relaxation rate scale, a simplified CORCEMA theory can be formulated using a generalized average relaxation rate matrix. Its range of validity is established by comparing its predictions with those of the exact CORCEMA theory which is valid for all exchange rates. Using some ideal model systems we have analyzed the factors that influence the ligand proton intensity changes when the resonances from some protons on the receptor protein are saturated. The results show that the intensity changes in the ligand signals in an intermolecular NOE experiment are very much dependent upon: (1) the saturation time, (2) the location of the saturated receptor protons with respect to the ligand protons, (3) the conformation of the ligand-receptor interface, (4) the rotational correlation times for the molecular species, (5) the kinetics of the reversibly forming complex, and (6) the ligand/receptor ratio. As an example of a typical application of the STD-NMR experiment we have also simulated the STD effects for a
Dielectric Relaxation of Water: Theory and Experiment

International Nuclear Information System (INIS)

Adhikari, Narayan Prasad; Paudyal, Harihar; Johri, Manoj

2010-06-01

We have studied the hydrogen bond dynamics and methods for evaluation of probability and relaxation time for hydrogen bond network. Further, dielectric relaxation time has been calculated by using a diagonalization procedure by obtaining eigen values (inverse of relaxation time) of a master equation framed on the basis of Fokker-Planck equations. Microwave cavity spectrometer has been described to make measurements of relaxation time. Slater's perturbation equations are given for the analysis of the data. A comparison of theoretical and experimental data shows that there is a need for improvements in the theoretical model and experimental techniques to provide exact information about structural properties of water. (author)
Optical excitation and electron relaxation dynamics at semiconductor surfaces: a combined approach of density functional and density matrix theory applied to the silicon (001) surface

Energy Technology Data Exchange (ETDEWEB)

Buecking, N

2007-11-05

In this work a new theoretical formalism is introduced in order to simulate the phononinduced relaxation of a non-equilibrium distribution to equilibrium at a semiconductor surface numerically. The non-equilibrium distribution is effected by an optical excitation. The approach in this thesis is to link two conventional, but approved methods to a new, more global description: while semiconductor surfaces can be investigated accurately by density-functional theory, the dynamical processes in semiconductor heterostructures are successfully described by density matrix theory. In this work, the parameters for density-matrix theory are determined from the results of density-functional calculations. This work is organized in two parts. In Part I, the general fundamentals of the theory are elaborated, covering the fundamentals of canonical quantizations as well as the theory of density-functional and density-matrix theory in 2{sup nd} order Born approximation. While the formalism of density functional theory for structure investigation has been established for a long time and many different codes exist, the requirements for density matrix formalism concerning the geometry and the number of implemented bands exceed the usual possibilities of the existing code in this field. A special attention is therefore attributed to the development of extensions to existing formulations of this theory, where geometrical and fundamental symmetries of the structure and the equations are used. In Part II, the newly developed formalism is applied to a silicon (001)surface in a 2 x 1 reconstruction. As first step, density-functional calculations using the LDA functional are completed, from which the Kohn-Sham-wave functions and eigenvalues are used to calculate interaction matrix elements for the electron-phonon-coupling an the optical excitation. These matrix elements are determined for the optical transitions from valence to conduction bands and for electron-phonon processes inside the
A Block-Asynchronous Relaxation Method for Graphics Processing Units

OpenAIRE

Anzt, H.; Dongarra, J.; Heuveline, Vincent; Tomov, S.

2011-01-01

In this paper, we analyze the potential of asynchronous relaxation methods on Graphics Processing Units (GPUs). For this purpose, we developed a set of asynchronous iteration algorithms in CUDA and compared them with a parallel implementation of synchronous relaxation methods on CPU-based systems. For a set of test matrices taken from the University of Florida Matrix Collection we monitor the convergence behavior, the average iteration time and the total time-to-solution time. Analyzing the r...
Information matrix estimation procedures for cognitive diagnostic models.

Science.gov (United States)

Liu, Yanlou; Xin, Tao; Andersson, Björn; Tian, Wei

2018-03-06

Two new methods to estimate the asymptotic covariance matrix for marginal maximum likelihood estimation of cognitive diagnosis models (CDMs), the inverse of the observed information matrix and the sandwich-type estimator, are introduced. Unlike several previous covariance matrix estimators, the new methods take into account both the item and structural parameters. The relationships between the observed information matrix, the empirical cross-product information matrix, the sandwich-type covariance matrix and the two approaches proposed by de la Torre (2009, J. Educ. Behav. Stat., 34, 115) are discussed. Simulation results show that, for a correctly specified CDM and Q-matrix or with a slightly misspecified probability model, the observed information matrix and the sandwich-type covariance matrix exhibit good performance with respect to providing consistent standard errors of item parameter estimates. However, with substantial model misspecification only the sandwich-type covariance matrix exhibits robust performance. © 2018 The British Psychological Society.
Mechanical confinement regulates cartilage matrix formation by chondrocytes

Science.gov (United States)

Lee, Hong-Pyo; Gu, Luo; Mooney, David J.; Levenston, Marc E.; Chaudhuri, Ovijit

2017-12-01

Cartilage tissue equivalents formed from hydrogels containing chondrocytes could provide a solution for replacing damaged cartilage. Previous approaches have often utilized elastic hydrogels. However, elastic stresses may restrict cartilage matrix formation and alter the chondrocyte phenotype. Here we investigated the use of viscoelastic hydrogels, in which stresses are relaxed over time and which exhibit creep, for three-dimensional (3D) culture of chondrocytes. We found that faster relaxation promoted a striking increase in the volume of interconnected cartilage matrix formed by chondrocytes. In slower relaxing gels, restriction of cell volume expansion by elastic stresses led to increased secretion of IL-1β, which in turn drove strong up-regulation of genes associated with cartilage degradation and cell death. As no cell-adhesion ligands are presented by the hydrogels, these results reveal cell sensing of cell volume confinement as an adhesion-independent mechanism of mechanotransduction in 3D culture, and highlight stress relaxation as a key design parameter for cartilage tissue engineering.
Pseudo-transient Continuation Based Variable Relaxation Solve in Nonlinear Magnetohydrodynamic Simulations

International Nuclear Information System (INIS)

Chen, Jin

2009-01-01

Efficient and robust Variable Relaxation Solver, based on pseudo-transient continuation, is developed to solve nonlinear anisotropic thermal conduction arising from fusion plasma simulations. By adding first and/or second order artificial time derivatives to the system, this type of method advances the resulting time-dependent nonlinear PDEs to steady state, which is the solution to be sought. In this process, only the stiffness matrix itself is involved so that the numerical complexity and errors can be greatly reduced. In fact, this work is an extension of integrating efficient linear elliptic solvers for fusion simulation on Cray XIE. Two schemes are derived in this work, first and second order Variable Relaxations. Four factors are observed to be critical for efficiency and preservation of solution's symmetric structure arising from periodic boundary condition: refining meshes in different coordinate directions, initializing nonlinear process, varying time steps in both temporal and spatial directions, and accurately generating nonlinear stiffness matrix. First finer mesh scale should be taken in strong transport direction; Next the system is carefully initialized by the solution with linear conductivity; Third, time step and relaxation factor are vertex-based varied and optimized at each time step; Finally, the nonlinear stiffness matrix is updated by just scaling corresponding linear one with the vector generated from nonlinear thermal conductivity.
Proximal Alternating Direction Method with Relaxed Proximal Parameters for the Least Squares Covariance Adjustment Problem

Directory of Open Access Journals (Sweden)

Minghua Xu

2014-01-01

Full Text Available We consider the problem of seeking a symmetric positive semidefinite matrix in a closed convex set to approximate a given matrix. This problem may arise in several areas of numerical linear algebra or come from finance industry or statistics and thus has many applications. For solving this class of matrix optimization problems, many methods have been proposed in the literature. The proximal alternating direction method is one of those methods which can be easily applied to solve these matrix optimization problems. Generally, the proximal parameters of the proximal alternating direction method are greater than zero. In this paper, we conclude that the restriction on the proximal parameters can be relaxed for solving this kind of matrix optimization problems. Numerical experiments also show that the proximal alternating direction method with the relaxed proximal parameters is convergent and generally has a better performance than the classical proximal alternating direction method.
Electron relaxation properties of Ar magnetron plasmas

Science.gov (United States)

Xinjing, CAI; Xinxin, WANG; Xiaobing, ZOU

2018-03-01

An understanding of electron relaxation properties in plasmas is of importance in the application of magnetrons. An improved multi-term approximation of the Boltzmann equation is employed to study electron transport and relaxation properties in plasmas. Elastic, inelastic and nonconservative collisions between electrons and neutral particles are considered. The expressions for the transport coefficients are obtained using the expansion coefficients and the collision operator term. Numerical solutions of the matrix equations for the expansion coefficients are also investigated. Benchmark calculations of the Reid model are presented to demonstrate the accuracy of the improved multi-term approximation. It is shown that the two-term approximation is generally not accurate enough and the magnetic fields can reduce the anisotropy of the velocity distribution function. The electron relaxation properties of Ar plasmas in magnetrons for various magnetic fields are studied. It is demonstrated that the energy parameters change more slowly than the momentum parameters.
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.
Pseudo-transient Continuation Based Variable Relaxation Solve in Nonlinear Magnetohydrodynamic Simulations

Energy Technology Data Exchange (ETDEWEB)

Jin Chen

2009-12-07

Efficient and robust Variable Relaxation Solver, based on pseudo-transient continuation, is developed to solve nonlinear anisotropic thermal conduction arising from fusion plasma simulations. By adding first and/or second order artificial time derivatives to the system, this type of method advances the resulting time-dependent nonlinear PDEs to steady state, which is the solution to be sought. In this process, only the stiffness matrix itself is involved so that the numerical complexity and errors can be greatly reduced. In fact, this work is an extension of integrating efficient linear elliptic solvers for fusion simulation on Cray XIE. Two schemes are derived in this work, first and second order Variable Relaxations. Four factors are observed to be critical for efficiency and preservation of solution's symmetric structure arising from periodic boundary condition: refining meshes in different coordinate directions, initializing nonlinear process, varying time steps in both temporal and spatial directions, and accurately generating nonlinear stiffness matrix. First finer mesh scale should be taken in strong transport direction; Next the system is carefully initialized by the solution with linear conductivity; Third, time step and relaxation factor are vertex-based varied and optimized at each time step; Finally, the nonlinear stiffness matrix is updated by just scaling corresponding linear one with the vector generated from nonlinear thermal conductivity.

Energy relaxation and transfer in excitonic trimer

International Nuclear Information System (INIS)

Herman, Pavel; Barvik, Ivan; Urbanec, Martin

2004-01-01

Two models describing exciton relaxation and transfer (the Redfield model in the secular approximation and Capek's model) are compared for a simple example - a symmetric trimer coupled to a phonon bath. Energy transfer within the trimer occurs via resonance interactions and coupling between the trimer and the bath occurs via modulation of the monomer energies by phonons. Two initial conditions are adopted: (1) one of higher eigenstates of the trimer is initially occupied and (2) one local site of the trimer is initially occupied. The diagonal exciton density matrix elements in the representation of eigenstates are found to be the same for both models, but this is not so for the off-diagonal density matrix elements. Only if the off-diagonal density matrix elements vanish initially (initial condition (1)), they then vanish at arbitrary times in both models. If the initial excitation is local, the off-diagonal matrix elements essentially differ
Thermal stress relaxation in magnesium composites during thermal cycling

Energy Technology Data Exchange (ETDEWEB)

Trojanova, Z.; Lukac, P. (Karlova Univ., Prague (Czech Republic)); Kiehn, J.; Kainer, K.U.; Mordike, B.L. (Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany))

1998-01-01

It has been shown that the internal friction of Mg - Saffil metal matrix composites can be influenced by thermal stresses, if MMCc are submitted to thermal cycling between room temperature and an upper temperature of cycling. These stresses can be accommodated by generation and motion of dislocations giving the formation of the microplastic zones. The thermal stress relaxation depends on the upper temperature of cycling, the volume fraction of reinforcement and the matrix composition and can result in plastic deformation and strain hardening of the matrix without applied stress. The internal friction measurements can be used for non destructive investigation of processes which influence the mechanical properties. (orig.)
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.
Relaxation response of A533B steel from 25 to 600/degree/C

International Nuclear Information System (INIS)

Swindeman, R.W.; Bolling, E.

1989-01-01

Relaxation tests were performed on A533B steel over the range 25 to 600/degree/C in order to examine the general features of time- dependent deformation. It was found that the relaxation strength increased with the flow stress at low temperatures and was relatively independent of history at high temperatures. In the temperature range 400 to 600/degree/C the inelastic strain rates calculated from the relaxation rates followed stress dependencies that were consistent with expectations based on a model proposed by Hart and coworkers for matrix deformation. 21 refs., 10 figs
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.
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
Concomitant use of the matrix strategy and the mand-model procedure in teaching graphic symbol combinations.

Science.gov (United States)

Nigam, Ravi; Schlosser, Ralf W; Lloyd, Lyle L

2006-09-01

Matrix strategies employing parts of speech arranged in systematic language matrices and milieu language teaching strategies have been successfully used to teach word combining skills to children who have cognitive disabilities and some functional speech. The present study investigated the acquisition and generalized production of two-term semantic relationships in a new population using new types of symbols. Three children with cognitive disabilities and little or no functional speech were taught to combine graphic symbols. The matrix strategy and the mand-model procedure were used concomitantly as intervention procedures. A multiple probe design across sets of action-object combinations with generalization probes of untrained combinations was used to teach the production of graphic symbol combinations. Results indicated that two of the three children learned the early syntactic-semantic rule of combining action-object symbols and demonstrated generalization to untrained action-object combinations and generalization across trainers. The results and future directions for research are discussed.
A Microstructural Study of Load Distribution in Cartilage: A Comparison of Stress Relaxation versus Creep Loading

Directory of Open Access Journals (Sweden)

Ashvin Thambyah

2015-01-01

Full Text Available The compressive response of articular cartilage has been extensively investigated and most studies have focussed largely on the directly loaded matrix. However, especially in relation to the tissue microstructure, less is known about load distribution mechanisms operating outside the directly loaded region. We have addressed this issue by using channel indentation and DIC microscopy techniques that provide visualisation of the matrix microstructural response across the regions of both direct and nondirect loading. We hypothesise that, by comparing the microstructural response following stress relaxation and creep compression, new insights can be revealed concerning the complex mechanisms of load bearing. Our results indicate that, with stress relaxation, the initial mode of stress decay appears to primarily involve relaxation of the surface layer. In the creep loading protocol, the main mode of stress release is a lateral distribution of load via the mid matrix. While these two modes of stress redistribution have a complex relationship with the zonally differentiated tissue microstructure and the depth of strain, four mechanostructural mechanisms are proposed to describe succinctly the load responses observed.
Ber analysis of the box relaxation for BPSK signal recovery

KAUST Repository

Thrampoulidis, Christos

2016-06-24

We study the problem of recovering an n-dimensional BPSK signal from m linear noise-corrupted measurements using the box relaxation method which relaxes the discrete set {±1}n to the convex set [-1,1]n to obtain a convex optimization algorithm followed by hard thresholding. When the noise and measurement matrix have iid standard normal entries, we obtain an exact expression for the bit-wise probability of error Pe in the limit of n and m growing and m/n fixed. At high SNR our result shows that the Pe of box relaxation is within 3dB of the matched filter bound (MFB) for square systems, and that it approaches the (MFB) as m grows large compared to n. Our results also indicate that as m, n → ∞, for any fixed set of size k, the error events of the corresponding k bits in the box relaxation method are independent.
Ber analysis of the box relaxation for BPSK signal recovery

KAUST Repository

Thrampoulidis, Christos; Abbasi, Ehsan; Xu, Weiyu; Hassibi, Babak

2016-01-01

We study the problem of recovering an n-dimensional BPSK signal from m linear noise-corrupted measurements using the box relaxation method which relaxes the discrete set {±1}n to the convex set [-1,1]n to obtain a convex optimization algorithm followed by hard thresholding. When the noise and measurement matrix have iid standard normal entries, we obtain an exact expression for the bit-wise probability of error Pe in the limit of n and m growing and m/n fixed. At high SNR our result shows that the Pe of box relaxation is within 3dB of the matched filter bound (MFB) for square systems, and that it approaches the (MFB) as m grows large compared to n. Our results also indicate that as m, n → ∞, for any fixed set of size k, the error events of the corresponding k bits in the box relaxation method are independent.
Onsager relaxation of toroidal plasmas

International Nuclear Information System (INIS)

Samain, A.; Nguyen, F.

1997-01-01

The slow relaxation of isolated toroidal plasmas towards their thermodynamical equilibrium is studied in an Onsager framework based on the entropy metric. The basic tool is a variational principle, equivalent to the kinetic equation, involving the profiles of density, temperature, electric potential, electric current. New minimization procedures are proposed to obtain entropy and entropy production rate functionals. (author)
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)
Effectiveness of relaxation techniques before diagnostic screening of cancer patients

Directory of Open Access Journals (Sweden)

Montserrat Aiger

2016-07-01

Full Text Available Psychophysiological arousal was observed in cancer patients during the application of relaxation techniques prior to a diagnostic scan (PET-CT. The aim of the study is twofold: firstly, it is sought to establish whether such techniques can minimize patient arousal before diagnostic screening begins, and secondly to measure which of them are most effective. The dependent variable is electrodermal activity, recording the attentional level and emotional response, and the independent variable comprises the relaxation techniques used, namely Jacobson, breathing and visualization. The 39 patients were split into experimental groups to whom the relaxation techniques (Jacobson, breathing exercises, and visualization were applied before they went for the PET-CT. An activity-module procedure was applied to track electrodermal activity during the relaxation sessions, consisting of instructions, timeout; wait, task; relaxation and end of the recording session. The control group received no relaxation techniques before the PET-CT. Session-end results show that patients who perform relaxation techniques achieve greater attentional focus using Jacobson's technique (M = .212 and enhanced emotional containment using visualization (M = .206. It is concluded that relaxation techniques minimize the state of activation during the waiting period before a diagnostic scan.
Temperature dependence of electron spin-lattice relaxation of radiation-produced silver atoms in polycrystalline aqueous and glassy organic matrices. Importance of relaxation by tunneling modes in disordered matrices

International Nuclear Information System (INIS)

Michalik, J.; Kevan, L.

1978-01-01

The electron spin-lattice relaxation of trapped silver atoms in polycrystalline ice matrices and in methanol, ethanol, propylene carbonate, and 2-methyltetrahydrofuran organic glasses has been directly studied as a function of temperature by the saturation-recovery method. Below 40 K the dominant electron spin-lattice relaxation mechanism involves modulation of the electron nuclear dipolar interaction with nuclei in the radical's environment by tunneling of those nuclei between two nearly equal energy configurations. This relaxation mechanism occurs with high efficiency, has a characteristic linear temperature dependence, and is typically found in highly disordered matrices. The efficiency of this relaxation mechanism seems to decrease with decreasing polarity of the matrix. Deuteration experiments show that the tunneling nuclei are protons and in methanol it is shown that the methyl protons have more tunneling modes available than the hydroxyl protons. In polycrystalline ice matrices silver atoms can be stabilized with two different orientations of surrounding water molecules; the efficiency of the tunneling relaxation reflects this difference. From these and previous results on tunneling relaxation of trapped electrons in glassy matrices it appears that tunneling relaxation may be used to distinguish models with different geometrical configurations and to determine the relative rigidity of such configurations around trapped radicals in disordered solids. (author)
Fourier transform distribution function of relaxation times; application and limitations

NARCIS (Netherlands)

Boukamp, Bernard A.

2015-01-01

A simple Fourier transform (FT) method is presented for obtaining a Distribution Function of Relaxation Times (DFRT) for electrochemical impedance spectroscopy (EIS) data. By using a special data extension procedure the FT is performed over the range from -∞ ≤ lnω ≤ + ∞. The integration procedure is
Successive Over Relaxation Method Which Uses Matrix Norms for ...

African Journals Online (AJOL)

An algorithm for S.O.R functional iteration which uses matrix norms for the Jacobi iteration matrices rather than the usual Power method, feasible in Newton Operator for the solution of nonlinear system of equations is proposed. We modified the S.O.R. iterative method known as Multiphase S.O.R. method for Newton ...
relaxGUI: a new software for fast and simple NMR relaxation data analysis and calculation of ps-ns and μs motion of proteins

International Nuclear Information System (INIS)

Bieri, Michael; D’Auvergne, Edward J.; Gooley, Paul R.

2011-01-01

Investigation of protein dynamics on the ps-ns and μs-ms timeframes provides detailed insight into the mechanisms of enzymes and the binding properties of proteins. Nuclear magnetic resonance (NMR) is an excellent tool for studying protein dynamics at atomic resolution. Analysis of relaxation data using model-free analysis can be a tedious and time consuming process, which requires good knowledge of scripting procedures. The software relaxGUI was developed for fast and simple model-free analysis and is fully integrated into the software package relax. It is written in Python and uses wxPython to build the graphical user interface (GUI) for maximum performance and multi-platform use. This software allows the analysis of NMR relaxation data with ease and the generation of publication quality graphs as well as color coded images of molecular structures. The interface is designed for simple data analysis and management. The software was tested and validated against the command line version of relax.
relaxGUI: a new software for fast and simple NMR relaxation data analysis and calculation of ps-ns and μs motion of proteins.

Science.gov (United States)

Bieri, Michael; d'Auvergne, Edward J; Gooley, Paul R

2011-06-01

Investigation of protein dynamics on the ps-ns and μs-ms timeframes provides detailed insight into the mechanisms of enzymes and the binding properties of proteins. Nuclear magnetic resonance (NMR) is an excellent tool for studying protein dynamics at atomic resolution. Analysis of relaxation data using model-free analysis can be a tedious and time consuming process, which requires good knowledge of scripting procedures. The software relaxGUI was developed for fast and simple model-free analysis and is fully integrated into the software package relax. It is written in Python and uses wxPython to build the graphical user interface (GUI) for maximum performance and multi-platform use. This software allows the analysis of NMR relaxation data with ease and the generation of publication quality graphs as well as color coded images of molecular structures. The interface is designed for simple data analysis and management. The software was tested and validated against the command line version of relax.
Evolutionary Pseudo-Relaxation Learning Algorithm for Bidirectional Associative Memory

Institute of Scientific and Technical Information of China (English)

Sheng-Zhi Du; Zeng-Qiang Chen; Zhu-Zhi Yuan

2005-01-01

This paper analyzes the sensitivity to noise in BAM (Bidirectional Associative Memory), and then proves the noise immunity of BAM relates not only to the minimum absolute value of net inputs (MAV) but also to the variance of weights associated with synapse connections. In fact, it is a positive monotonically increasing function of the quotient of MAV divided by the variance of weights. Besides, the performance of pseudo-relaxation method depends on learning parameters (λ and ζ), but the relation of them is not linear. So it is hard to find a best combination of λ and ζ which leads to the best BAM performance. And it is obvious that pseudo-relaxation is a kind of local optimization method, so it cannot guarantee to get the global optimal solution. In this paper, a novel learning algorithm EPRBAM (evolutionary psendo-relaxation learning algorithm for bidirectional association memory) employing genetic algorithm and pseudo-relaxation method is proposed to get feasible solution of BAM weight matrix. This algorithm uses the quotient as the fitness of each individual and employs pseudo-relaxation method to adjust individual solution when it does not satisfy constraining condition any more after genetic operation. Experimental results show this algorithm improves noise immunity of BAM greatly. At the same time, EPRBAM does not depend on learning parameters and can get global optimal solution.
Towards Google matrix of brain

Energy Technology Data Exchange (ETDEWEB)

Shepelyansky, D.L., E-mail: dima@irsamc.ups-tlse.f [Laboratoire de Physique Theorique (IRSAMC), Universite de Toulouse, UPS, F-31062 Toulouse (France); LPT - IRSAMC, CNRS, F-31062 Toulouse (France); Zhirov, O.V. [Budker Institute of Nuclear Physics, 630090 Novosibirsk (Russian Federation)

2010-07-12

We apply the approach of the Google matrix, used in computer science and World Wide Web, to description of properties of neuronal networks. The Google matrix G is constructed on the basis of neuronal network of a brain model discussed in PNAS 105 (2008) 3593. We show that the spectrum of eigenvalues of G has a gapless structure with long living relaxation modes. The PageRank of the network becomes delocalized for certain values of the Google damping factor {alpha}. The properties of other eigenstates are also analyzed. We discuss further parallels and similarities between the World Wide Web and neuronal networks.

Towards Google matrix of brain

International Nuclear Information System (INIS)

Shepelyansky, D.L.; Zhirov, O.V.

2010-01-01

We apply the approach of the Google matrix, used in computer science and World Wide Web, to description of properties of neuronal networks. The Google matrix G is constructed on the basis of neuronal network of a brain model discussed in PNAS 105 (2008) 3593. We show that the spectrum of eigenvalues of G has a gapless structure with long living relaxation modes. The PageRank of the network becomes delocalized for certain values of the Google damping factor α. The properties of other eigenstates are also analyzed. We discuss further parallels and similarities between the World Wide Web and neuronal networks.
NMR relaxation times of natural rubber latex

International Nuclear Information System (INIS)

Harun, S.; Aziz, H.; Basir, Z.

1994-01-01

NMR relaxation times T sub 1 and T sub 2 of natural rubber latex have been measured at 25 degree C on a pulsed NMR spectrometer. The work focuses on the variation of the relaxation times with the amount of water content from 0% to 50%. The water content was adjusted by centrifuging and removing a certain amount of water from the sample. The data were analysed using a biexponential fitting procedure which yields simultaneously either T sub 1a and T sub 1b or T sub 2a and T sub 2b. The amount of solid was compared with the known amount of dry rubber content
Multiple-Relaxation-Time Lattice Boltzmann Approach to Richtmyer-Meshkov Instability

International Nuclear Information System (INIS)

Chen Feng; Li Yingjun; Xu Aiguo; Zhang Guangcai

2011-01-01

The aims of the present paper are twofold. At first, we further study the Multiple-Relaxation-Time (MRT) Lattice Boltzmann (LB) model proposed in [Europhys. Lett. 90 (2010) 54003]. We discuss the reason why the Gram-Schmidt orthogonalization procedure is not needed in the construction of transformation matrix M; point out a reason why the Kataoka-Tsutahara model [Phys. Rev. E 69 (2004) 035701 (R)] is only valid in subsonic flows. The von Neumann stability analysis is performed. Secondly, we carry out a preliminary quantitative study on the Richtmyer-Meshkov instability using the proposed MRT LB model. When a shock wave travels from a light medium to a heavy one, the simulated growth rate is in qualitative agreement with the perturbation model by Zhang-Sohn. It is about half of the predicted value by the impulsive model and is closer to the experimental result. When the shock wave travels from a heavy medium to a light one, our simulation results are also consistent with physical analysis. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Quasiparticle relaxation in Heavy Fermions studied using Inverse Fourier Transform of optical conductivity

International Nuclear Information System (INIS)

Dordevic, S.V.

2012-01-01

Inverse Fourier Transform of optical conductivity is used for studies of quasiparticle relaxation in Heavy Fermions in time domain. We demonstrate the usefulness of the procedure on model spectra and then use it to study quasiparticle relaxation in two Heavy Fermions YbFe 4 Sb 12 and CeRu 4 Sb 12 . Optical conductivity in time domain reveals details of quasiparticle relaxation close to the Fermi level, not readily accessible from the spectra in the frequency domain. In particular, we find that the relaxation of heavy quasiparticles does not start instantaneously, but typically after a few hundred femto-seconds.
Relaxation of fibrils in blends with one viscoelastic component: Bulk and confined conditions

NARCIS (Netherlands)

Cardinaels, R.M.; Moldenaers, P.

2010-01-01

Using a counter rotating parallel plate shear flow cell, shape relaxation of fibrils in a quiescent matrix is studied microscopically. Both the effects of geometrical confinement and component viscoelasticity are systematically explored. By applying a supercritical shear flow for varying amounts of
A novel three-dimensional mesh deformation method based on sphere relaxation

International Nuclear Information System (INIS)

Zhou, Xuan; Li, Shuixiang

2015-01-01

In our previous work (2013) [19], we developed a disk relaxation based mesh deformation method for two-dimensional mesh deformation. In this paper, the idea of the disk relaxation is extended to the sphere relaxation for three-dimensional meshes with large deformations. We develop a node based pre-displacement procedure to apply initial movements on nodes according to their layer indices. Afterwards, the nodes are moved locally by the improved sphere relaxation algorithm to transfer boundary deformations and increase the mesh quality. A three-dimensional mesh smoothing method is also adopted to prevent the occurrence of the negative volume of elements, and further improve the mesh quality. Numerical applications in three-dimension including the wing rotation, bending beam and morphing aircraft are carried out. The results demonstrate that the sphere relaxation based approach generates the deformed mesh with high quality, especially regarding complex boundaries and large deformations
A novel three-dimensional mesh deformation method based on sphere relaxation

Energy Technology Data Exchange (ETDEWEB)

Zhou, Xuan [Department of Mechanics & Engineering Science, College of Engineering, Peking University, Beijing, 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing, 100094 (China); Li, Shuixiang, E-mail: lsx@pku.edu.cn [Department of Mechanics & Engineering Science, College of Engineering, Peking University, Beijing, 100871 (China)

2015-10-01

In our previous work (2013) [19], we developed a disk relaxation based mesh deformation method for two-dimensional mesh deformation. In this paper, the idea of the disk relaxation is extended to the sphere relaxation for three-dimensional meshes with large deformations. We develop a node based pre-displacement procedure to apply initial movements on nodes according to their layer indices. Afterwards, the nodes are moved locally by the improved sphere relaxation algorithm to transfer boundary deformations and increase the mesh quality. A three-dimensional mesh smoothing method is also adopted to prevent the occurrence of the negative volume of elements, and further improve the mesh quality. Numerical applications in three-dimension including the wing rotation, bending beam and morphing aircraft are carried out. The results demonstrate that the sphere relaxation based approach generates the deformed mesh with high quality, especially regarding complex boundaries and large deformations.
Markov state modeling and dynamical coarse-graining via discrete relaxation path sampling.

Science.gov (United States)

Fačkovec, B; Vanden-Eijnden, E; Wales, D J

2015-07-28

A method is derived to coarse-grain the dynamics of complex molecular systems to a Markov jump process (MJP) describing how the system jumps between cells that fully partition its state space. The main inputs are relaxation times for each pair of cells, which are shown to be robust with respect to positioning of the cell boundaries. These relaxation times can be calculated via molecular dynamics simulations performed in each cell separately and are used in an efficient estimator for the rate matrix of the MJP. The method is illustrated through applications to Sinai billiards and a cluster of Lennard-Jones discs.
The Relaxation Matrix for Symmetric Tops with Inversion Symmetry. II; Line Mixing Effects in the V1 Band of NH3

Science.gov (United States)

Boulet, C.; Ma, Q.

2016-01-01

Line mixing effects have been calculated in the ?1 parallel band of self-broadened NH3. The theoretical approach is an extension of a semi-classical model to symmetric-top molecules with inversion symmetry developed in the companion paper [Q. Ma and C. Boulet, J. Chem. Phys. 144, 224303 (2016)]. This model takes into account line coupling effects and hence enables the calculation of the entire relaxation matrix. A detailed analysis of the various coupling mechanisms is carried out for Q and R inversion doublets. The model has been applied to the calculation of the shape of the Q branch and of some R manifolds for which an obvious signature of line mixing effects has been experimentally demonstrated. Comparisons with measurements show that the present formalism leads to an accurate prediction of the available experimental line shapes. Discrepancies between the experimental and theoretical sets of first order mixing parameters are discussed as well as some extensions of both theory and experiment.
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.
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...
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
An inversion-relaxation approach for sampling stationary points of spin model Hamiltonians

International Nuclear Information System (INIS)

Hughes, Ciaran; Mehta, Dhagash; Wales, David J.

2014-01-01

Sampling the stationary points of a complicated potential energy landscape is a challenging problem. Here, we introduce a sampling method based on relaxation from stationary points of the highest index of the Hessian matrix. We illustrate how this approach can find all the stationary points for potentials or Hamiltonians bounded from above, which includes a large class of important spin models, and we show that it is far more efficient than previous methods. For potentials unbounded from above, the relaxation part of the method is still efficient in finding minima and transition states, which are usually the primary focus of attention for atomistic systems
Impact of a yogurt matrix and cell microencapsulation on the survival of Lactobacillus reuteri in three in vitro gastric digestion procedures.

Science.gov (United States)

Champagne, C P; Raymond, Y; Guertin, N; Martoni, C J; Jones, M L; Mainville, I; Arcand, Y

2015-01-01

The goal of this study was to assess the interaction between microencapsulation and a yogurt food matrix on the survival of Lactobacillus reuteri NCIMB 30242 in four different in vitro systems that simulate a gastric environment. The four systems were: United States Pharmacopeia (USP) solutions, a static two-step (STS) procedure which included simulated food ingredients, a constantly dynamic digestion procedure (IViDiS), as well a multi-step dynamic digestion scheme (S'IViDiS). The pH profiles of the various procedures varied between systems with acidity levels being: USP > STS > IViDiS = S'IVIDiS. Addition of a food matrix increased the pH in all systems except for the USP methodology. Microencapsulation in alginate-based gels was effective in protecting the cells in model solutions when no food ingredients were present. The stability of the probiotic culture in the in vitro gastric environments was enhanced when (1) yoghurt or simulated food ingredient were present in the medium in sufficient quantity, (2) pH was higher. The procedure-comparison data of this study will be helpful in interpreting the literature with respect to viable counts of probiotics obtained from different static or dynamic in vitro gastric systems.
Effects of relaxation on psychobiological wellbeing during pregnancy: a randomized controlled trial.

Science.gov (United States)

Urech, Corinne; Fink, Nadine S; Hoesli, Irène; Wilhelm, Frank H; Bitzer, Johannes; Alder, Judith

2010-10-01

Prenatal maternal stress is associated with adverse birth outcomes and may be reduced by relaxation exercises. The aim of the present study was to compare the immediate effects of two active and one passive 10-min relaxation technique on perceived and physiological indicators of relaxation. 39 healthy pregnant women recruited at the outpatient department of the University Women's Hospital Basel participated in a randomized controlled trial with an experimental repeated measure design. Participants were assigned to one of two active relaxation techniques, progressive muscle relaxation (PMR) or guided imagery (GI), or a passive relaxation control condition. Self-reported relaxation on a visual analogue scale (VAS) and state anxiety (STAI-S), endocrine parameters indicating hypothalamic-pituitary-adrenal (HPA) axis (cortisol and ACTH) and sympathetic-adrenal-medullary (SAM) system activity (norepinephrine and epinephrine), as well as cardiovascular responses (heart rate, systolic and diastolic blood pressure) were measured at four time points before and after the relaxation exercise. Between group differences showed, that compared to the PMR and control conditions, GI was significantly more effective in enhancing levels of relaxation and together with PMR, GI was associated with a significant decrease in heart rate. Within the groups, passive as well as active relaxation procedures were associated with a decline in endocrine measures except epinephrine. Taken together, these data indicate that different types of relaxation had differential effects on various psychological and biological stress systems. GI was especially effective in inducing self-reported relaxation in pregnant women while at the same time reducing cardiovascular activity. Copyright © 2010 Elsevier Ltd. All rights reserved.
Automated NMR relaxation dispersion data analysis using NESSY

Directory of Open Access Journals (Sweden)

Gooley Paul R

2011-10-01

Full Text Available Abstract Background Proteins are dynamic molecules with motions ranging from picoseconds to longer than seconds. Many protein functions, however, appear to occur on the micro to millisecond timescale and therefore there has been intense research of the importance of these motions in catalysis and molecular interactions. Nuclear Magnetic Resonance (NMR relaxation dispersion experiments are used to measure motion of discrete nuclei within the micro to millisecond timescale. Information about conformational/chemical exchange, populations of exchanging states and chemical shift differences are extracted from these experiments. To ensure these parameters are correctly extracted, accurate and careful analysis of these experiments is necessary. Results The software introduced in this article is designed for the automatic analysis of relaxation dispersion data and the extraction of the parameters mentioned above. It is written in Python for multi platform use and highest performance. Experimental data can be fitted to different models using the Levenberg-Marquardt minimization algorithm and different statistical tests can be used to select the best model. To demonstrate the functionality of this program, synthetic data as well as NMR data were analyzed. Analysis of these data including the generation of plots and color coded structures can be performed with minimal user intervention and using standard procedures that are included in the program. Conclusions NESSY is easy to use open source software to analyze NMR relaxation data. The robustness and standard procedures are demonstrated in this article.
Thermal relaxation of charm in hadronic matter

Energy Technology Data Exchange (ETDEWEB)

He Min, E-mail: mhe@comp.tamu.edu [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); Fries, Rainer J. [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States); RIKEN/BNL Research Center, Brookhaven National Laboratory, Upton, NY 11973 (United States); Rapp, Ralf [Cyclotron Institute and Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843 (United States)

2011-07-18

The thermal relaxation rate of open-charm (D) mesons in hot and dense hadronic matter is calculated using empirical elastic scattering amplitudes. D-meson interactions with thermal pions are approximated by D{sup *} resonances, while scattering off other hadrons (K, {eta}, {rho}, {omega}, K{sup *}, N, {Delta}) is evaluated using vacuum scattering amplitudes as available in the literature based on effective Lagrangians and constrained by realistic spectroscopy. The thermal relaxation time of D-mesons in a hot {pi} gas is found to be around 25-50 fm/c for temperatures T=150-180 MeV, which reduces to 10-25 fm/c in a hadron-resonance gas. The latter values, argued to be conservative estimates, imply significant modifications of D-meson spectra in heavy-ion collisions. Close to the critical temperature (T{sub c}), the spatial diffusion coefficient (D{sub s}) is surprisingly similar to recent calculations for charm quarks in the Quark-Gluon Plasma using non-perturbative T-matrix interactions. This suggests a possibly continuous minimum structure of D{sub s} around T{sub c}.
Quasi-normal modes from non-commutative matrix dynamics

Science.gov (United States)

Aprile, Francesco; Sanfilippo, Francesco

2017-09-01

We explore similarities between the process of relaxation in the BMN matrix model and the physics of black holes in AdS/CFT. Focusing on Dyson-fluid solutions of the matrix model, we perform numerical simulations of the real time dynamics of the system. By quenching the equilibrium distribution we study quasi-normal oscillations of scalar single trace observables, we isolate the lowest quasi-normal mode, and we determine its frequencies as function of the energy. Considering the BMN matrix model as a truncation of N=4 SYM, we also compute the frequencies of the quasi-normal modes of the dual scalar fields in the AdS5-Schwarzschild background. We compare the results, and we finda surprising similarity.
Paramagnetic relaxation effects in perturbed angular correlations for arbitrary electronic relaxation time

International Nuclear Information System (INIS)

Chopin, C.; Spanjaard, D.; Hartmann-Boutron, F.

1975-01-01

Previous perturbation treatments of paramagnetic relaxation effects in γγ PAC were limited to the case of very short electronic relaxation times. This limitation is circumvented by invoking a new perturbation theory recently elaborated by Hirst and others for handling relaxation effects in Moessbauer spectra. Under the assumption of spherical electronic relaxation the perturbation factors are computed as functions of certain relaxation parameters which are directly related to the microscopic relaxation Hamiltonian. The results are compared to those of the stochastic theory of Scherer and Blume [fr
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.

Relaxation path of metastable nanoclusters in oxide dispersion strengthened materials

Energy Technology Data Exchange (ETDEWEB)

Ribis, J., E-mail: joel.ribis@cea.fr [DEN-Service de Recherches Métallurgiques Appliquées, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Thual, M.A. [LLB, CEA, CNRS, Université Paris-Saclay, CEA Saclay, 91191, Gif-sur-Yvette (France); Guilbert, T.; Carlan, Y. de [DEN-Service de Recherches Métallurgiques Appliquées, CEA, Université Paris-Saclay, F-91191, Gif-sur-Yvette (France); Legris, A. [UMET, CNRS/UMR 8207, Bât. C6, Univ. Lille 1, 59655 Villeneuve d’Ascq (France)

2017-02-15

ODS steels are a promising class of structural materials for sodium cooled fast reactor application. The ultra-high density of the strengthening nanoclusters dispersed within the ferritic matrix is responsible of the excellent creep properties of the alloy. Fine characterization of the nanoclusters has been conducted on a Fe-14Cr-0.3Ti-0.3Y{sub 2}O{sub 3} ODS material using High Resolution and Energy Filtered Transmission Electron Microscopy. The nanoclusters exhibit a cubic symmetry possibly identified as f.c.c and display a non-equilibrium YTiCrO chemical composition thought to be stabilized by a vacancy supersaturation. These nanoclusters undergo relaxation towards the Y{sub 2}Ti{sub 2}O{sub 7}-like state as they grow. A Cr shell is observed around the relaxed nano-oxides, this size-dependent shell may form after the release of Cr by the particles. The relaxation energy barrier appears to be higher for the smaller particles probably owing to a volume/surface ratio effect in reason to the full coherency of the nanoclusters. - Highlights: • The nanoclusters display a f.c.c. cubic symmetry and a non-equilibrium YTiCrO chemical composition. • During thermal annealing the coherent nanocluster transform into semi-coherent pyrochlore particles. • A Cr ring is observed around the relaxed pyrochlore type particles.
Some fundamental aspects of fault-tree and digraph-matrix relationships for a systems-interaction evaluation procedure

International Nuclear Information System (INIS)

Alesso, H.P.

1982-01-01

Recent events, such as Three Mile Island-2, Brown's Ferry-3, and Crystal River-3, have demonstrated that complex accidents can occur as a result of dependent (common-cause/mode) failures. These events are now being called Systems Interactions. A procedure for the identification and evaluation of Systems Interactions is being developed by the NRC. Several national laboratories and utilities have contributed preliminary procedures. As a result, there are several important views of the Systems Interaction problem. This report reviews some fundamental mathematical background of both fault-oriented and success-oriented risk analyses in order to bring out the advantages and disadvantages of each. In addition, it outlines several fault-oriented/dependency analysis approaches and several success-oriented/digraph-matrix approaches. The objective is to obtain a broad perspective of present options for solving the Systems Interaction problem
Matrix completion via a low rank factorization model and an Augmented Lagrangean Succesive Overrelaxation Algorithm

Directory of Open Access Journals (Sweden)

Hugo Lara

2014-12-01

Full Text Available The matrix completion problem (MC has been approximated by using the nuclear norm relaxation. Some algorithms based on this strategy require the computationally expensive singular value decomposition (SVD at each iteration. One way to avoid SVD calculations is to use alternating methods, which pursue the completion through matrix factorization with a low rank condition. In this work an augmented Lagrangean-type alternating algorithm is proposed. The new algorithm uses duality information to define the iterations, in contrast to the solely primal LMaFit algorithm, which employs a Successive Over Relaxation scheme. The convergence result is studied. Some numerical experiments are given to compare numerical performance of both proposals.
Mechanical forces regulate the interactions of fibronectin and collagen I in extracellular matrix.

Science.gov (United States)

Kubow, Kristopher E; Vukmirovic, Radmila; Zhe, Lin; Klotzsch, Enrico; Smith, Michael L; Gourdon, Delphine; Luna, Sheila; Vogel, Viola

2015-08-14

Despite the crucial role of extracellular matrix (ECM) in directing cell fate in healthy and diseased tissues--particularly in development, wound healing, tissue regeneration and cancer--the mechanisms that direct the assembly and regulate hierarchical architectures of ECM are poorly understood. Collagen I matrix assembly in vivo requires active fibronectin (Fn) fibrillogenesis by cells. Here we exploit Fn-FRET probes as mechanical strain sensors and demonstrate that collagen I fibres preferentially co-localize with more-relaxed Fn fibrils in the ECM of fibroblasts in cell culture. Fibre stretch-assay studies reveal that collagen I's Fn-binding domain is responsible for the mechano-regulated interaction. Furthermore, we show that Fn-collagen interactions are reciprocal: relaxed Fn fibrils act as multivalent templates for collagen assembly, but once assembled, collagen fibres shield Fn fibres from being stretched by cellular traction forces. Thus, in addition to the well-recognized, force-regulated, cell-matrix interactions, forces also tune the interactions between different structural ECM components.
Nonequilibrium dynamics of one-dimensional hard-core anyons following a quench: complete relaxation of one-body observables.

Science.gov (United States)

Wright, Tod M; Rigol, Marcos; Davis, Matthew J; Kheruntsyan, Karén V

2014-08-01

We demonstrate the role of interactions in driving the relaxation of an isolated integrable quantum system following a sudden quench. We consider a family of integrable hard-core lattice anyon models that continuously interpolates between noninteracting spinless fermions and strongly interacting hard-core bosons. A generalized Jordan-Wigner transformation maps the entire family to noninteracting fermions. We find that, aside from the singular free-fermion limit, the entire single-particle density matrix and, therefore, all one-body observables relax to the predictions of the generalized Gibbs ensemble (GGE). This demonstrates that, in the presence of interactions, correlations between particles in the many-body wave function provide the effective dissipation required to drive the relaxation of all one-body observables to the GGE. This relaxation does not depend on translational invariance or the tracing out of any spatial domain of the system.
Delocalization transition for the Google matrix.

Science.gov (United States)

Giraud, Olivier; Georgeot, Bertrand; Shepelyansky, Dima L

2009-08-01

We study the localization properties of eigenvectors of the Google matrix, generated both from the world wide web and from the Albert-Barabási model of networks. We establish the emergence of a delocalization phase for the PageRank vector when network parameters are changed. For networks with localized PageRank, eigenvalues of the matrix in the complex plane with a modulus above a certain threshold correspond to localized eigenfunctions while eigenvalues below this threshold are associated with delocalized relaxation modes. We argue that, for networks with delocalized PageRank, the efficiency of information retrieval by Google-type search is strongly affected since the PageRank values have no clear hierarchical structure in this case.
Dynamical X-ray scattering from the relaxed structures

International Nuclear Information System (INIS)

Benediktovitch, A.; Feranchuk, I.; Ulyanenkov, A.

2009-01-01

High-resolution X-ray diffraction is now widely used analytical tool for investigation of nano scale multilayered structures in semiconductor and optical technologies. The HRXRD method delivers unique information on the crystallographic lattice of the samples, concentration of solid solutions, lattice mismatches, layer thicknesses, defect distribution, and relaxation degree of the epitaxial layers. The evaluation of the experimental results, however, requires a robust and precise theory due to complex dynamical scattering of X-rays from near perfect crystallographic structure of the samples. Usually, the Takagi-Taupin approach [1] or the recurrent matrix methods [2] are used for the simulation of the X-ray diffraction profiles from the epitaxial multilayered structures. The use of these theories, however, becomes essentially difficult, when the lateral lattice mismatches are present in multilayers, for example, in the case of partially or fully relaxed epitaxially grown samples. In the present work, the general solution of this problem is found analytically. The angular divergence of the incident beam is also considered and the algorithm for the diffracted profile mapping in the reciprocal space is developed. The experimental reciprocal space mapping of typical AlGaN/GaN/AlN samples with partially relaxed layers is compared to the simulated maps, which describe well the location and character of the diffraction spots caused by different layers. (author)
Google matrix analysis of DNA sequences.

Science.gov (United States)

Kandiah, Vivek; Shepelyansky, Dima L

2013-01-01

For DNA sequences of various species we construct the Google matrix [Formula: see text] of Markov transitions between nearby words composed of several letters. The statistical distribution of matrix elements of this matrix is shown to be described by a power law with the exponent being close to those of outgoing links in such scale-free networks as the World Wide Web (WWW). At the same time the sum of ingoing matrix elements is characterized by the exponent being significantly larger than those typical for WWW networks. This results in a slow algebraic decay of the PageRank probability determined by the distribution of ingoing elements. The spectrum of [Formula: see text] is characterized by a large gap leading to a rapid relaxation process on the DNA sequence networks. We introduce the PageRank proximity correlator between different species which determines their statistical similarity from the view point of Markov chains. The properties of other eigenstates of the Google matrix are also discussed. Our results establish scale-free features of DNA sequence networks showing their similarities and distinctions with the WWW and linguistic networks.
Google matrix analysis of DNA sequences.

Directory of Open Access Journals (Sweden)

Vivek Kandiah

Full Text Available For DNA sequences of various species we construct the Google matrix [Formula: see text] of Markov transitions between nearby words composed of several letters. The statistical distribution of matrix elements of this matrix is shown to be described by a power law with the exponent being close to those of outgoing links in such scale-free networks as the World Wide Web (WWW. At the same time the sum of ingoing matrix elements is characterized by the exponent being significantly larger than those typical for WWW networks. This results in a slow algebraic decay of the PageRank probability determined by the distribution of ingoing elements. The spectrum of [Formula: see text] is characterized by a large gap leading to a rapid relaxation process on the DNA sequence networks. We introduce the PageRank proximity correlator between different species which determines their statistical similarity from the view point of Markov chains. The properties of other eigenstates of the Google matrix are also discussed. Our results establish scale-free features of DNA sequence networks showing their similarities and distinctions with the WWW and linguistic networks.
Langevin equation method for the rotational Brownian motion and orientational relaxation in liquids: II. Symmetrical top molecules

CERN Document Server

Coffey, W T; Titov, S V

2003-01-01

A theory of orientational relaxation for the inertial rotational Brownian motion of a symmetric top molecule is developed using the Langevin equation rather than the Fokker-Planck equation. The infinite hierarchy of differential-recurrence relations for the orientational correlation functions for the relaxation behaviour is derived by averaging the corresponding Euler-Langevin equations. The solution of this hierarchy is obtained using matrix continued fractions allowing the calculation of the correlation times and the spectra of the orientational correlation functions for typical values of the model parameters.
Cross-relaxation imaging:methods, challenges and applications

International Nuclear Information System (INIS)

Stikov, Nikola

2010-01-01

An overview of quantitative magnetization transfer (qMT) is given, with focus on cross relaxation imaging (CRI) as a fast method for quantifying the proportion of protons bound to complex macromolecules in tissue. The procedure for generating CRI maps is outlined, showing examples in the human brain and knee, and discussing the caveats and challenges in generating precise and accurate CRI maps. Finally, several applications of CRI for imaging tissue microstructure are presented.(Author)
Fuzzy risk matrix

International Nuclear Information System (INIS)

Markowski, Adam S.; Mannan, M. Sam

2008-01-01

A risk matrix is a mechanism to characterize and rank process risks that are typically identified through one or more multifunctional reviews (e.g., process hazard analysis, audits, or incident investigation). This paper describes a procedure for developing a fuzzy risk matrix that may be used for emerging fuzzy logic applications in different safety analyses (e.g., LOPA). The fuzzification of frequency and severity of the consequences of the incident scenario are described which are basic inputs for fuzzy risk matrix. Subsequently using different design of risk matrix, fuzzy rules are established enabling the development of fuzzy risk matrices. Three types of fuzzy risk matrix have been developed (low-cost, standard, and high-cost), and using a distillation column case study, the effect of the design on final defuzzified risk index is demonstrated
Segmental dynamics in polymer melts by relaxation techniques and quasielastic neutron scattering

Science.gov (United States)

Colmenero, J.

1993-01-01

The dynamics of the segmental α-relaxation in three different polymeric systems, poly(vinyl methy 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 timescale ranging from mesoscopic to macroscopic times (10-10-101s). 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 timescale shows a clear non-Debye behaviour. The shape of the relaxation function 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) propto Q-n (n > 2) n being dependent on the system, and that the Q-behaviour and the non-Debye behaviour are directly correlated. We discuss this correlation taking into account several data of the dynamics of the α-relaxation previously reported in the literature. We also outline a possible scenario for explaining this empirical correlation.
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)
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.
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.
Flux-split algorithms for flows with non-equilibrium chemistry and vibrational relaxation

Science.gov (United States)

Grossman, B.; Cinnella, P.

1990-01-01

The present consideration of numerical computation methods for gas flows with nonequilibrium chemistry thermodynamics gives attention to an equilibrium model, a general nonequilibrium model, and a simplified model based on vibrational relaxation. Flux-splitting procedures are developed for the fully-coupled inviscid equations encompassing fluid dynamics and both chemical and internal energy-relaxation processes. A fully coupled and implicit large-block structure is presented which embodies novel forms of flux-vector split and flux-difference split algorithms valid for nonequilibrium flow; illustrative high-temperature shock tube and nozzle flow examples are given.
Internal stress relaxation and load redistribution during the twinning-detwinning-dominated cyclic deformation of a wrought magnesium alloy, ZK60A

International Nuclear Information System (INIS)

Wu, L.; Agnew, S.R.; Brown, D.W.; Stoica, G.M.; Clausen, B.; Jain, A.; Fielden, D.E.; Liaw, P.K.

2008-01-01

A study of the internal strain (stress) evolution during cyclic deformation dominated by {101-bar2} twinning and detwinning mechanisms within a magnesium alloy, ZK60A, was conducted using in situ neutron diffraction. It is shown that once the matrix grains twin, the (00.2) matrix and twin grains are relaxed relative to the neighbors. This load redistribution between the soft- and hard-grain orientations is a result of plastic anisotropy. The twins which formed during the initial compression sustain a tensile stress along the c-axis, when the applied compressive stress is less than ∼80 MPa upon unloading. This local (intergranular) tensile stress is hypothesized to be effective for driving the detwinning event under a macroscopic compressive field along the c-axis. The activation stresses, 15 and 6 MPa, respectively, for the {101-bar2} extension twinning and detwinning, are approximated, based on the relaxation of the internal stresses in the matrix and twin grains
Matrix-based introduction to multivariate data analysis

CERN Document Server

Adachi, Kohei

2016-01-01

This book enables readers who may not be familiar with matrices to understand a variety of multivariate analysis procedures in matrix forms. Another feature of the book is that it emphasizes what model underlies a procedure and what objective function is optimized for fitting the model to data. The author believes that the matrix-based learning of such models and objective functions is the fastest way to comprehend multivariate data analysis. The text is arranged so that readers can intuitively capture the purposes for which multivariate analysis procedures are utilized: plain explanations of the purposes with numerical examples precede mathematical descriptions in almost every chapter. This volume is appropriate for undergraduate students who already have studied introductory statistics. Graduate students and researchers who are not familiar with matrix-intensive formulations of multivariate data analysis will also find the book useful, as it is based on modern matrix formulations with a special emphasis on ...
Fast treatment plan modification with an over-relaxed Cimmino algorithm

International Nuclear Information System (INIS)

Wu Chuan; Jeraj, Robert; Lu Weiguo; Mackie, Thomas R.

2004-01-01

A method to quickly modify a treatment plan in adaptive radiotherapy was proposed and studied. The method is based on a Cimmino-type algorithm in linear programming. The fast convergence speed is achieved by over-relaxing the algorithm relaxation parameter from its sufficient convergence range of (0, 2) to (0, ∞). The algorithm parameters are selected so that the over-relaxed Cimmino (ORC) algorithm can effectively approximate an unconstrained re-optimization process in adaptive radiotherapy. To demonstrate the effectiveness and flexibility of the proposed method in adaptive radiotherapy, two scenarios with different organ motion/deformation of one nasopharyngeal case were presented with comparisons made between this method and the re-optimization method. In both scenarios, the ORC algorithm modified treatment plans have dose distributions that are similar to those given by the re-optimized treatment plans. It takes us using the ORC algorithm to finish a treatment plan modification at least three times faster than the re-optimization procedure compared

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
Pair plasma relaxation time scales.

Science.gov (United States)

Aksenov, A G; Ruffini, R; Vereshchagin, G V

2010-04-01

By numerically solving the relativistic Boltzmann equations, we compute the time scale for relaxation to thermal equilibrium for an optically thick electron-positron plasma with baryon loading. We focus on the time scales of electromagnetic interactions. The collisional integrals are obtained directly from the corresponding QED matrix elements. Thermalization time scales are computed for a wide range of values of both the total-energy density (over 10 orders of magnitude) and of the baryonic loading parameter (over 6 orders of magnitude). This also allows us to study such interesting limiting cases as the almost purely electron-positron plasma or electron-proton plasma as well as intermediate cases. These results appear to be important both for laboratory experiments aimed at generating optically thick pair plasmas as well as for astrophysical models in which electron-positron pair plasmas play a relevant role.
General framework for studying the dynamics of folded and nonfolded proteins by NMR relaxation spectroscopy and MD simulation

NARCIS (Netherlands)

Prompers, J.J.; Brüschweiler, R.

2002-01-01

A general framework is presented for the interpretation of NMR relaxation data of proteins. The method, termed isotropic reorientational eigenmode dynamics (iRED), relies on a principal component analysis of the isotropically averaged covariance matrix of the lattice functions of the spin
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

Smith's (2001) Attentional Behavioral Cognitive (ABC) relaxation theory proposes that all approaches to relaxation (including music) have the potential for evoking one or more of 15 factor-analytically derived relaxation states, or "R-States" (Sleepiness, Disengagement, Rested / Refreshed, Energized, Physical Relaxation, At Ease/Peace, Joy, Mental Quiet, Childlike Innocence, Thankfulness and Love, Mystery, Awe and Wonder, Prayerfulness, Timeless/Boundless/Infinite, and Aware). The present study investigated R-States and stress symptom-patterns associated with listening to Mozart versus New Age music. Students (N = 63) were divided into three relaxation groups based on previously determined preferences. Fourteen listened to a 28-minute tape recording of Mozart's Eine Kleine Nachtmusik and 14 listened to a 28-minute tape of Steven Halpern's New Age Serenity Suite. Others (n = 35) did not want music and instead chose a set of popular recreational magazines. Participants engaged in their relaxation activity at home for three consecutive days for 28 minutes a session. Before and after each session, each person completed the Smith Relaxation States Inventory (Smith, 2001), a comprehensive questionnaire tapping 15 R-States as well as the stress states of somatic stress, worry, and negative emotion. Results revealed no differences at Session 1. At Session 2, those who listened to Mozart reported higher levels of At Ease/Peace and lower levels of Negative Emotion. Pronounced differences emerged at Session 3. Mozart listeners uniquely reported substantially higher levels of Mental Quiet, Awe and Wonder, and Mystery. Mozart listeners reported higher levels, and New Age listeners slightly elevated levels, of At Ease/Peace and Rested/Refreshed. Both Mozart and New Age listeners reported higher levels of Thankfulness and Love. In summary, those who listened to Mozart's Eine Kleine Nachtmusik reported more psychological relaxation and less stress than either those who listened to
Current leakage relaxation and charge trapping in ultra-porous low-k materials

International Nuclear Information System (INIS)

Borja, Juan; Plawsky, Joel L.; Gill, William N.; Lu, T.-M.; Bakhru, Hassaram

2014-01-01

Time dependent dielectric failure has become a pivotal aspect of interconnect design as industry pursues integration of sub-22 nm process-technology nodes. Literature has provided key information about the role played by individual species such as electrons, holes, ions, and neutral impurity atoms. However, no mechanism has been shown to describe how such species interact and influence failure. Current leakage relaxation in low-k dielectrics was studied using bipolar field experiments to gain insight into how charge carrier flow becomes impeded by defects within the dielectric matrix. Leakage current decay was correlated to injection and trapping of electrons. We show that current relaxation upon inversion of the applied field can be described by the stretched exponential function. The kinetics of charge trapping events are consistent with a time-dependent reaction rate constant, k=k 0 ⋅(t+1) β−1 , where 0 < β < 1. Such dynamics have previously been observed in studies of charge trapping reactions in amorphous solids by W. H. Hamill and K. Funabashi, Phys. Rev. B 16, 5523–5527 (1977). We explain the relaxation process in charge trapping events by introducing a nonlinear charge trapping model. This model provides a description on the manner in which the transport of mobile defects affects the long-tail current relaxation processes in low-k films
The nuclear reaction matrix

International Nuclear Information System (INIS)

Krenciglowa, E.M.; Kung, C.L.; Kuo, T.T.S.; Osnes, E.; and Department of Physics, State University of New York at Stony Brook, Stony Brook, New York 11794)

1976-01-01

Different definitions of the reaction matrix G appropriate to the calculation of nuclear structure are reviewed and discussed. Qualitative physical arguments are presented in support of a two-step calculation of the G-matrix for finite nuclei. In the first step the high-energy excitations are included using orthogonalized plane-wave intermediate states, and in the second step the low-energy excitations are added in, using harmonic oscillator intermediate states. Accurate calculations of G-matrix elements for nuclear structure calculations in the Aapprox. =18 region are performed following this procedure and treating the Pauli exclusion operator Q 2 /sub p/ by the method of Tsai and Kuo. The treatment of Q 2 /sub p/, the effect of the intermediate-state spectrum and the energy dependence of the reaction matrix are investigated in detail. The present matrix elements are compared with various matrix elements given in the literature. In particular, close agreement is obtained with the matrix elements calculated by Kuo and Brown using approximate methods
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
Multiple-relaxation-time lattice Boltzmann model for compressible fluids

International Nuclear Information System (INIS)

Chen Feng; Xu Aiguo; Zhang Guangcai; Li Yingjun

2011-01-01

We present an energy-conserving multiple-relaxation-time finite difference lattice Boltzmann model for compressible flows. The collision step is first calculated in the moment space and then mapped back to the velocity space. The moment space and corresponding transformation matrix are constructed according to the group representation theory. Equilibria of the nonconserved moments are chosen according to the need of recovering compressible Navier-Stokes equations through the Chapman-Enskog expansion. Numerical experiments showed that compressible flows with strong shocks can be well simulated by the present model. The new model works for both low and high speeds compressible flows. It contains more physical information and has better numerical stability and accuracy than its single-relaxation-time version. - Highlights: → We present an energy-conserving MRT finite-difference LB model. → The moment space is constructed according to the group representation theory. → The new model works for both low and high speeds compressible flows. → It has better numerical stability and wider applicable range than its SRT version.
Optimal homotopy asymptotic method for solving fractional relaxation-oscillation equation

Directory of Open Access Journals (Sweden)

Mohammad Hamarsheh

2015-11-01

Full Text Available In this paper, an approximate analytical solution of linear fractional relaxation-oscillation equations in which the fractional derivatives are given in the Caputo sense, is obtained by the optimal homotopy asymptotic method (OHAM. The studied OHAM is based on minimizing the residual error. The results given by OHAM are compared with the exact solutions and the solutions obtained by generalized Taylor matrix method. The reliability and efficiency of the proposed approach are demonstrated in three examples with the aid of the symbolic algebra program Maple.
The Relaxation Matrix for Symmetric Tops with Inversion Symmetry. I. Effects of Line Coupling on Self-Broadened v (sub 1) and Pure Rotational Bands of NH3

Science.gov (United States)

Ma, Q.; Boulet, C.

2016-01-01

The Robert-Bonamy formalism has been commonly used to calculate half-widths and shifts of spectral lines for decades. This formalism is based on several approximations. Among them, two have not been fully addressed: the isolated line approximation and the neglect of coupling between the translational and internal motions. Recently, we have shown that the isolated line approximation is not necessary in developing semi-classical line shape theories. Based on this progress, we have been able to develop a new formalism that enables not only to reduce uncertainties on calculated half-widths and shifts, but also to model line mixing effects on spectra starting from the knowledge of the intermolecular potential. In our previous studies, the new formalism had been applied to linear and asymmetric-top molecules. In the present study, the method has been extended to symmetric-top molecules with inversion symmetry. As expected, the inversion splitting induces a complete failure of the isolated line approximation. We have calculated the complex relaxation matrices of selfbroadened NH3. The half-widths and shifts in the ?1 and the pure rotational bands are reported in the present paper. When compared with measurements, the calculated half-widths match the experimental data very well, since the inapplicable isolated line approximation has been removed. With respect to the shifts, only qualitative results are obtained and discussed. Calculated off-diagonal elements of the relaxation matrix and a comparison with the observed line mixing effects are reported in the companion paper (Paper II).
High Temperature Performance Evaluation of As-serviced 25Cr35Ni Type Heat-resistant Steel Based on Stress Relaxation Tests

Directory of Open Access Journals (Sweden)

XU Jun

2017-08-01

Full Text Available Based on an as-serviced 25Cr35Ni type steel, the high temperature property evaluation using stress relaxation test(SRT method and residual life prediction were studied. The results show that creep rupture property decreases because of the formation of network carbides along grain boundaries and coarsening of secondary carbides in the austenitic matrix. Based on the relationship of stress relaxation strain rate curves obtained at different temperatures, and the extrapolation equation of stress relaxation rate-rupture time, it is capable to perform residual life evaluation by combining SRT data and a small amount of creep rupture test(CRT. Good agreement is observed for predicting results performed by current method and traditional method.
Strength and fracture behavior of aluminide matrix composites with ceramic fibers

Energy Technology Data Exchange (ETDEWEB)

Inoue, M.; Suganuma, K.; Niihara, K.

1999-07-01

This paper investigates the fracture behavior of FeAl and Ni{sub 3}Al matrix composites with ceramic continuous fibers 8.5--10 {micro}m in diameter. When stress is applied to these composites, multiple-fracture of fibers predominantly occurs before matrix cracking, because the load carried by the fibers reaches their fracture strength. Fragments which remain longer than the critical length can provide significant strengthening through load bearing even though fiber breaking has occurred. The ultimate fracture strength of the composites also depends on stress relaxation by plastic deformation of the matrix at a crack tip in the multiple-fractured fibers. Ductilizing of the matrix by B doping improves the ultimate strength at ambient temperatures in both composites. However, their mechanical properties at elevated temperatures are quite different. In the case of Ni{sub 3}Al matrix composites, embrittlement of the matrix is undesirable for high strength and reliability at 873--973 K.
Fetal responses to induced maternal relaxation during pregnancy.

Science.gov (United States)

DiPietro, Janet A; Costigan, Kathleen A; Nelson, Priscilla; Gurewitsch, Edith D; Laudenslager, Mark L

2008-01-01

Fetal responses to induced maternal relaxation during the 32nd week of pregnancy were recorded in 100 maternal-fetal pairs using a digitized data collection system. The 18-min guided imagery relaxation manipulation generated significant changes in maternal heart rate, skin conductance, respiration period, and respiratory sinus arrhythmia. Significant alterations in fetal neurobehavior were observed, including decreased fetal heart rate (FHR), increased FHR variability, suppression of fetal motor activity (FM), and increased FM-FHR coupling. Attribution of the two fetal cardiac responses to the guided imagery procedure itself, as opposed to simple rest or recumbency, is tempered by the observed pattern of response. Evaluation of correspondence between changes within individual maternal-fetal pairs revealed significant associations between maternal autonomic measures and fetal cardiac patterns, lower umbilical and uterine artery resistance and increased FHR variability, and declining salivary cortisol and FM activity. Potential mechanisms that may mediate the observed results are discussed.
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 ...
Definition of a matrix of the generalized parameters asymmetrical multiphase transmission lines

Directory of Open Access Journals (Sweden)

Suslov V.M.

2005-12-01

Full Text Available Idle time, without introduction of wave characteristics, algorithm of definition of a matrix of the generalized parameters asymmetrical multiphase transmission lines is offered. Definition of a matrix of parameters is based on a matrix primary specific of parameters of line and simple iterative procedure. The amount of iterations of iterative procedure is determined by a set error of performance of the resulted matrix ratio between separate blocks of a determined matrix. The given error is connected by close image of with a margin error determined matrix.
Sleep, Stress & Relaxation: Rejuvenate Body & Mind

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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
MR imaging of the stomach and relaxation measurement with intraluminal hyperpolarized 129Xenon gas

International Nuclear Information System (INIS)

Yanagawa, Yasuhiro; Kimura, Atsuomi; Fujiwara, Hideaki; Kinoshita, Yoshimasa; Hattori, Mineyuki; Hiraga, Takashi; Iida, Hidehiro

2001-01-01

Using laser optical pumping, the nuclear spin polarization of noble gases can be strongly enhanced. The purpose of this study was to make a simple apparatus that can provide hyperpolarized 129 Xe gas, which can then be used in an attempt to obtain magnetic resonance imaging (MRI). We would also like to study the relaxation behavior of hyperpolarized 129 Xe gas through the measurement of the relaxation time. First, we demonstrated that hyperpolarized 129 Xe gas can be applied to magnetic resonance imaging of the stomach, by using a rat as a model. This was performed under a 4.7 T magnet field using the following imaging parameters for the hyperpolarized 129 Xe gas: TR=50 ms, TE=15 ms, FOV=10 x 10 cm 2 , matrix size 64 x 64, THK=2.54 cm. By using these parameters, we were able to obtain a hyperpolarized image of the stomach in rats for the first time. Next, we measured the relaxation times of the hyperpolarized 129 Xe gas enclosed in cavities such as the stomach of rats as well as in phantoms created by glass and gelatin bulbs. The cavity size dependency of the relaxation time was analyzed on the basis of the kinetic theory of gases. This analysis showed a linear relationship between the relaxation rate (1/T 1 ) and a square inverse of the cavity diameter (1/d 2 ). From this relationship, the wall effect on the 129 Xe relaxation can be estimated in the novel parameter t 1 , wall . This shows drastic dependency on the material of the wall, suggesting a potential use of the relaxation experiment as a diagnostic tool for organ surfaces in the future. (author)
The effects of progressive muscle relaxation and autogenic relaxation on young soccer players' mood states.

Science.gov (United States)

Hashim, Hairul Anuar; Hanafi Ahmad Yusof, Hazwani

2011-06-01

This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players' mood states.
Gamma dosimetric parameters in some skeletal muscle relaxants

Science.gov (United States)

Manjunatha, H. C.

2017-09-01

We have studied the attenuation of gamma radiation of energy ranging from 84 keV to 1330 keV (^{170}Tm, ^{22}Na,^{137}Cs, and ^{60}Co) in some commonly used skeletal muscle relaxants such as tubocurarine chloride, gallamine triethiodide, pancuronium bromide, suxamethonium bromide and mephenesin. The mass attenuation coefficient is measured from the attenuation experiment. In the present work, we have also proposed the direct relation between mass attenuation coefficient (μ /ρ ) and mass energy absorption coefficient (μ _{en}/ρ ) based on the nonlinear fitting procedure. The gamma dosimetric parameters such as mass energy absorption coefficient (μ _{en}/ρ ), effective atomic number (Z_{eff}), effective electron density (N_{el}), specific γ-ray constant, air kerma strength and dose rate are evaluated from the measured mass attentuation coefficient. These measured gamma dosimetric parameters are compared with the theoretical values. The measured values agree with the theoretical values. The studied gamma dosimetric values for the relaxants are useful in medical physics and radiation medicine.

Construction of the exact Fisher information matrix of Gaussian time series models by means of matrix differential rules

NARCIS (Netherlands)

Klein, A.A.B.; Melard, G.; Zahaf, T.

2000-01-01

The Fisher information matrix is of fundamental importance for the analysis of parameter estimation of time series models. In this paper the exact information matrix of a multivariate Gaussian time series model expressed in state space form is derived. A computationally efficient procedure is used
The Effects of Progressive Muscle Relaxation and Autogenic Relaxation on Young Soccer Players’ Mood States

Science.gov (United States)

Hashim, Hairul Anuar; Hanafi@Ahmad Yusof, Hazwani

2011-01-01

Purpose This study was designed to compare the effects of two different relaxation techniques, namely progressive muscle relaxation (PMR) and autogenic relaxation (AGR) on moods of young soccer players. Methods Sixteen adolescent athletes (mean age: 14.1 ± 1.3) received either PMR or AGR training. Using Profile of Mood States- Adolescents, their mood states were measured one week before relaxation training, before the first relaxation session, and after the twelfth relaxation session. Results Mixed ANOVA revealed no significant interaction effects and no significant main effects in any of the subscales. However, significant main effects for testing sessions were found for confusion, depression, fatigue, and tension subscales. Post hoc tests revealed post-intervention reductions in the confusion, depression, fatigue, and tension subscale scores. Conclusion These two relaxation techniques induce equivalent mood responses and may be used to regulate young soccer players’ mood states. PMID:22375225
Excited-state relaxation of Ag8 clusters embedded in helium droplets

International Nuclear Information System (INIS)

Radcliffe, Paul; Przystawik, Andreas; Diederich, Thomas; Doeppner, Tilo; Tiggesbaeumker, Josef; Meiwes-Broer, Karl-Heinz

2004-01-01

Neutral silver clusters Ag N are grown in ultracold helium nanodroplets. By exploiting a strong absorption resonance recently found for Ag 8 , first photoelectron spectra of this neutral species are recorded. Variation of the laser photon energy reveals that direct vertical two-photon ionization is hindered by rapid relaxation into the lower edge of a long-living excited state manifold. The analysis of the dynamics gives a precise value of (6.89±0.09) eV for the vertical ionization potential of Ag 8 . The influence of the helium matrix on photoemission is discussed
Dynamic relaxation method in analysis of reinforced concrete bent elements

Directory of Open Access Journals (Sweden)

Anna Szcześniak

2015-12-01

Full Text Available The paper presents a method for the analysis of nonlinear behaviour of reinforced concrete bent elements subjected to short-term static load. The considerations in the range of modelling of deformation processes of reinforced concrete element were carried out. The method of structure effort analysis was developed using the finite difference method. The Dynamic Relaxation Method, which — after introduction of critical damping — allows for description of the static behaviour of a structural element, was used to solve the system of nonlinear equilibrium equations. In order to increase the method effectiveness in the range of the post-critical analysis, the Arc Length Parameter on the equilibrium path was introduced into the computational procedure.[b]Keywords[/b]: reinforced concrete elements, physical nonlinearity, geometrical nonlinearity, dynamic relaxation method, arc-length method
Anisotropy and relaxation processes of uniaxially oriented CoFe2O4 nanoparticles dispersed in PDMS

International Nuclear Information System (INIS)

Antonel, P.S.; Negri, R.M.; Leyva, A.G.; Jorge, G.A.

2012-01-01

When a uniaxial magnetic field is applied to a non-magnetic dispersive medium filled with magnetic nanoparticles, they auto-assemble into thin needles parallel to the field direction, due to the strong dipolar interaction among them. We have prepared in this way magnetically oriented nanocomposites of nanometer-size CoFe 2 O 4 particles in a polydimethylsiloxane polymer matrix, with 10% w/w of magnetic particles. We present the characteristic magnetic relaxation curves measured after the application of a magnetic field forming an angle α with respect to the needle direction. We show that the magnetic viscosity (calculated from the logarithmic relaxation curves) as a function of α presents a minimum at α=0, indicating slower relaxation processes associated with this configuration of fields. The results seems to point out that the local magnetic anisotropy of the nanoparticles is oriented along the needles, resulting in the macroscopic magnetic anisotropy observed in our measurements.
Relax and Try This Instead: Abbreviated Habit Reversal for Maladaptive Self-Biting.

Science.gov (United States)

Jones, Kevin M.; Swearer, Susan M.; Friman, Patrick C.

1997-01-01

A study evaluated the effectiveness of an abbreviated habit reversal procedure to reduce maladaptive oral self-biting in an adolescent boy in residential care. Treatment involved a combination of relaxation and two competing responses (gum chewing and tongue-lip rubbing). The intervention eliminated the biting and the tissue damage it caused.…
Dashed line relaxing retinotomy in the management of retinal detachment with anterior proliferative vitreoretinopathy

Directory of Open Access Journals (Sweden)

Tsen CL

2015-04-01

Full Text Available Chui-Lien Tsen,1 Yu-Harn Horng,1 Shwu-Jiuan Sheu1,2 1Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan; 2School of Medicine, National Yang-Ming University, Taipei, Taiwan Background: We describe the anatomical and functional outcomes of eyes that underwent a modified technique of relaxing retinotomy, dashed line relaxing retinotomy, in the management of retinal detachment with anterior proliferative vitreoretinopathy.Methods: We retrospectively reviewed 54 consecutive eyes in 52 patients who received pars plana vitrectomy with relaxing retinotomy during retinal detachment repair. Perfluorocarbon liquid (PFCL was used as a standard procedure to stabilize the retina during retinotomy to prevent slippage or inversion of the posterior flap. If PFCL was not available due to economic reasons, dashed line relaxing retinotomy was performed instead. Best-corrected visual acuity, slit-lamp biomicroscopy, intraocular pressure measurement, lens status, and fundus examination were analyzed. We excluded patients who were followed up <4 months.Results: Regarding anatomical success rates and visual outcomes, we found no significant differences between patients treated with intraoperative PFCL and those treated with dashed line relaxing retinotomy without PFCL.Conclusion: Compared to the simple and efficient PFCL-assisted relaxing retinotomy, dashed relaxing retinotomy is not the first choice when PFCL is available. Based on our results, this modified technique may offer an alternative in patients with anterior proliferative vitreoretinopathy for whom PFCL is not available. Keywords: perfluorocarbon liquid, PFCL
Hybrid-hybrid matrix structural refinement of a DNA three-way junction from 3D NOESY-NOESY

International Nuclear Information System (INIS)

Thiviyanathan, Varatharasa; Luxon, Bruce A.; Leontis, Neocles B.; Illangasekare, Nishantha; Donne, David G.; Gorenstein, David G.

1999-01-01

Homonuclear 3D NOESY-NOESY has shown great promise for the structural refinement of large biomolecules. A computationally efficient hybrid-hybrid relaxation matrix refinement methodology, using 3D NOESY-NOESY data, was used to refine the structure of a DNA three-way junction having two unpaired bases at the branch point of the junction. The NMR data and the relaxation matrix refinement confirm that the DNA three-way junction exists in a folded conformation with two of the helical stems stacked upon each other. The third unstacked stem extends away from the junction, forming an acute angle (∼60 deg.) with the stacked stems. The two unpaired bases are stacked upon each other and are exposed to the solvent. Helical parameters for the bases in all three strands show slight deviations from typical values expected for right-handed B-form DNA. Inter-nucleotide imino-imino NOEs between the bases at the branch point of the junction show that the junction region is well defined. The helical stems show mobility (± 20 deg.) indicating dynamic processes around the junction region. The unstacked helical stem adjacent to the unpaired bases shows greater mobility compared to the other two stems. The results from this study indicate that the 3D hybrid-hybrid matrix MORASS refinement methodology, by combining the spectral dispersion of 3D NOESY-NOESY and the computational efficiency of 2D refinement programs, provides an accurate and robust means for structure determination of large biomolecules. Our results also indicate that the 3D MORASS method gives higher quality structures compared to the 2D complete relaxation matrix refinement method
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)
POLYMAT-C: a comprehensive SPSS program for computing the polychoric correlation matrix.

Science.gov (United States)

Lorenzo-Seva, Urbano; Ferrando, Pere J

2015-09-01

We provide a free noncommercial SPSS program that implements procedures for (a) obtaining the polychoric correlation matrix between a set of ordered categorical measures, so that it can be used as input for the SPSS factor analysis (FA) program; (b) testing the null hypothesis of zero population correlation for each element of the matrix by using appropriate simulation procedures; (c) obtaining valid and accurate confidence intervals via bootstrap resampling for those correlations found to be significant; and (d) performing, if necessary, a smoothing procedure that makes the matrix amenable to any FA estimation procedure. For the main purpose (a), the program uses a robust unified procedure that allows four different types of estimates to be obtained at the user's choice. Overall, we hope the program will be a very useful tool for the applied researcher, not only because it provides an appropriate input matrix for FA, but also because it allows the researcher to carefully check the appropriateness of the matrix for this purpose. The SPSS syntax, a short manual, and data files related to this article are available as Supplemental materials that are available for download with this article.
Semidefinite Relaxation-Based Optimization of Multiple-Input Wireless Power Transfer Systems

Science.gov (United States)

Lang, Hans-Dieter; Sarris, Costas D.

2017-11-01

An optimization procedure for multi-transmitter (MISO) wireless power transfer (WPT) systems based on tight semidefinite relaxation (SDR) is presented. This method ensures physical realizability of MISO WPT systems designed via convex optimization -- a robust, semi-analytical and intuitive route to optimizing such systems. To that end, the nonconvex constraints requiring that power is fed into rather than drawn from the system via all transmitter ports are incorporated in a convex semidefinite relaxation, which is efficiently and reliably solvable by dedicated algorithms. A test of the solution then confirms that this modified problem is equivalent (tight relaxation) to the original (nonconvex) one and that the true global optimum has been found. This is a clear advantage over global optimization methods (e.g. genetic algorithms), where convergence to the true global optimum cannot be ensured or tested. Discussions of numerical results yielded by both the closed-form expressions and the refined technique illustrate the importance and practicability of the new method. It, is shown that this technique offers a rigorous optimization framework for a broad range of current and emerging WPT applications.
Bulk viscosity of strongly interacting matter in the relaxation time approximation

Science.gov (United States)

Czajka, Alina; Hauksson, Sigtryggur; Shen, Chun; Jeon, Sangyong; Gale, Charles

2018-04-01

We show how thermal mean field effects can be incorporated consistently in the hydrodynamical modeling of heavy-ion collisions. The nonequilibrium correction to the distribution function resulting from a temperature-dependent mass is obtained in a procedure which automatically satisfies the Landau matching condition and is thermodynamically consistent. The physics of the bulk viscosity is studied here for Boltzmann and Bose-Einstein gases within the Chapman-Enskog and 14-moment approaches in the relaxation time approximation. Constant and temperature-dependent masses are considered in turn. It is shown that, in the small mass limit, both methods lead to the same value of the ratio of the bulk viscosity to its relaxation time. The inclusion of a temperature-dependent mass leads to the emergence of the βλ function in that ratio, and it is of the expected parametric form for the Boltzmann gas, while for the Bose-Einstein case it is affected by the infrared cutoff. This suggests that the relaxation time approximation may be too crude to obtain a reliable form of ζ /τR for gases obeying Bose-Einstein statistics.
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…
Table-sized matrix model in fractional learning

Science.gov (United States)

Soebagyo, J.; Wahyudin; Mulyaning, E. C.

2018-05-01

This article provides an explanation of the fractional learning model i.e. a Table-Sized Matrix model in which fractional representation and its operations are symbolized by the matrix. The Table-Sized Matrix are employed to develop problem solving capabilities as well as the area model. The Table-Sized Matrix model referred to in this article is used to develop an understanding of the fractional concept to elementary school students which can then be generalized into procedural fluency (algorithm) in solving the fractional problem and its operation.
The Effects of Progressive Relaxation and Music on Attention, Relaxation, and Stress Responses: An Investigation of the Cognitive-Behavioral Model of Relaxation

National Research Council Canada - National Science Library

Scheufele, Peter

1999-01-01

...) suggested that stress management techniques have specific effects A compromise position suggests that the specific effects of relaxation techniques are superimposed upon a general relaxation response...
Magnetic resonance imaging (MRI) and relaxation time mapping of concrete

Science.gov (United States)

Beyea, Steven Donald

2001-07-01

The use of Magnetic Resonance Imaging (MRI) of water in concrete is presented. This thesis will approach the problem of MR imaging of concrete by attempting to design new methods, suited to concrete materials, rather than attempting to force the material to suit the method. A number of techniques were developed, which allow the spatial observation of water in concrete in up to three dimensions, and permits the determination of space resolved moisture content, as well as local NMR relaxation times. These methods are all based on the Single-Point Imaging (SPI) method. The development of these new methods will be described, and the techniques validated using phantom studies. The study of one-dimensional moisture transport in drying concrete was performed using SPI. This work examined the effect of initial mixture proportions and hydration time on the drying behaviour of concrete, over a period of three months. Studies of drying concrete were also performed using spatial mapping of the spin-lattice (T1) and effective spin-spin (T2*) relaxation times, thereby permitting the observation of changes in the water occupied pore surface-to-volume ratio (S/V) as a function of drying. Results of this work demonstrated changes in the S/V due to drying, hydration and drying induced microcracking. Three-dimensional MRI of concrete was performed using SPRITE (Single-Point Ramped Imaging with T1 Enhancement) and turboSPI (turbo Single Point Imaging). While SPRITE allows for weighting of MR images using T 1 and T2*, turboSPI allows T2 weighting of the resulting images. Using relaxation weighting it was shown to be possible to discriminate between water contained within a hydrated cement matrix, and water in highly porous aggregates, used to produce low-density concrete. Three dimensional experiments performed using SPRITE and turboSPI examined the role of self-dessication, drying, initial aggregate saturation and initial mixture conditions on the transport of moisture between porous
CELLULAR CONTROL OF CONNECTIVE TISSUE MATRIX TENSION†

Science.gov (United States)

Langevin, Helene M.; Nedergaard, Maiken; Howe, Alan

2013-01-01

The biomechanical behavior of connective tissue in response to stretching is generally attributed to the molecular composition and organization of its extracellular matrix. It also is becoming apparent that fibroblasts play an active role in regulating connective tissue tension. In response to static stretching of the tissue, fibroblasts expand within minutes by actively remodeling their cytoskeleton. This dynamic change in fibroblast shape contributes to the drop in tissue tension that occurs during viscoelastic relaxation. We propose that this response of fibroblasts plays a role in regulating extracellular fluid flow into the tissue, and protects against swelling when the matrix is stretched. This article reviews the evidence supporting possible mechanisms underlying this response including autocrine purinergic signaling. We also discuss fibroblast regulation of connective tissue tension with respect to lymphatic flow, immune function and cancer. PMID:23444198
Cellular control of connective tissue matrix tension.

Science.gov (United States)

Langevin, Helene M; Nedergaard, Maiken; Howe, Alan K

2013-08-01

The biomechanical behavior of connective tissue in response to stretching is generally attributed to the molecular composition and organization of its extracellular matrix. It also is becoming apparent that fibroblasts play an active role in regulating connective tissue tension. In response to static stretching of the tissue, fibroblasts expand within minutes by actively remodeling their cytoskeleton. This dynamic change in fibroblast shape contributes to the drop in tissue tension that occurs during viscoelastic relaxation. We propose that this response of fibroblasts plays a role in regulating extracellular fluid flow into the tissue, and protects against swelling when the matrix is stretched. This article reviews the evidence supporting possible mechanisms underlying this response including autocrine purinergic signaling. We also discuss fibroblast regulation of connective tissue tension with respect to lymphatic flow, immune function, and cancer. Copyright © 2013 Wiley Periodicals, Inc.
A COMPARISOM BETWEEN THE EFFECTTIVENESS OF RELAXATION TRAINING AND PHARMACOTHERAPY IN TREATMENT OF PATIENTS WITH TENSION HEADACHE

Directory of Open Access Journals (Sweden)

R BAGHERIAN

2003-12-01

Full Text Available
Introduction: Headaches are the common cause of refferals to physicians, and among them, tension headache is the most prevalent. There is not consens us on the effectiveness of a specific therapeutic procedure. However, the purpose of this study was to identify the effects of relaxation training in comparison to pharmacotherapy in treatment of tension headache.
Procedures: The study employed an experiment design with two treatment group (N=12 One treatment group gaticipated in a relaxation training program over an 8-week period. A second treatment group was only given Amitriptyline. Data collected over a 2 - week period before and after treatment by using a dialy headache scale used by patients and visual analog scale used by one of the patient";s relatives. Back depression scale and zung Anxietys scale were used for evaluating levels of depression and Anxiety in patients.
Results: Mean score of improvement in relaxation training was significantly higher than that of Amitriptyline group (t=3.85 , P < 0.01 Also the relaxation group demonstrated lower mean score of headache peak than that of peak than that of Amitriptyline group (t=2.6, p < 0.01. However, regarding to visual analog scale there was no statistically significant difference between two groups.in respect of distribution of patients among different improvement levels, the relaxation training group was significantly better than Amitriptyline group (x₂=6.66, df=2, p < 0.01
Discussion: The relaxation training was more effective than Amitriptuline in decreasing headach for patients with tension headache.
Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

Science.gov (United States)

Minguillon, Jesus; Lopez-Gordo, Miguel Angel; Renedo-Criado, Diego A; Sanchez-Carrion, Maria Jose; Pelayo, Francisco

2017-01-01

Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group) or white (control group) lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes). We also observed a convergence time (3.5-5 minutes) after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

Blue lighting accelerates post-stress relaxation: Results of a preliminary study.

Directory of Open Access Journals (Sweden)

Jesus Minguillon

Full Text Available Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group or white (control group lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes. We also observed a convergence time (3.5-5 minutes after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.
Hyper-systolic matrix multiplication

NARCIS (Netherlands)

Lippert, Th.; Petkov, N.; Palazzari, P.; Schilling, K.

A novel parallel algorithm for matrix multiplication is presented. It is based on a 1-D hyper-systolic processor abstraction. The procedure can be implemented on all types of parallel systems. (C) 2001 Elsevier Science B,V. All rights reserved.
One-Dimensional Problem of a Conducting Viscous Fluid with One Relaxation Time

Directory of Open Access Journals (Sweden)

Angail A. Samaan

2011-01-01

Full Text Available We introduce a magnetohydrodynamic model of boundary-layer equations for conducting viscous fluids. This model is applied to study the effects of free convection currents with thermal relaxation time on the flow of a viscous conducting fluid. The method of the matrix exponential formulation for these equations is introduced. The resulting formulation together with the Laplace transform technique is applied to a variety problems. The effects of a plane distribution of heat sources on the whole and semispace are studied. Numerical results are given and illustrated graphically for the problem.
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....
Atomic level structural modulation during the structural relaxation and its effect on magnetic properties of Fe81Si4B10P4Cu1 nanocrystalline alloy

Science.gov (United States)

Cao, C. C.; Zhu, L.; Meng, Y.; Zhai, X. B.; Wang, Y. G.

2018-06-01

The evolution of local structure and defects in the Fe81Si4B10P4Cu1 amorphous alloy during the structural relaxation has been investigated by Mössbauer spectroscopy, positron annihilation lifetime spectroscopy and transmission electron microscopy to explore their effects on magnetic properties of the nanocrystalline. The atomic rearrangements at the early stage of the structural relaxation cause the density increase of the amorphous matrix, but the subsequent atomic rearrangements contribute to the transformation of Fe3B-like atomic arrangements to FeB-like ones with the temperature increasing. As the structural relaxation processes, the released Fe atoms both from Fe3B- and Fe3P-like atomic arrangements result in the formation of new Fe clusters and the increase of Fe-Fe coordination number in the existing Fe clusters and the nucleation sites for α-Fe gradually increase, both of which promote the crystallization. However, the homogeneity of amorphous matrix will be finally destroyed under excessive relaxation temperature, which coarsens nanograins during the crystallization instead. Therefore, soft magnetic properties of the Fe81Si4B10P4Cu1 nanocrystalline alloy can be improved by pre-annealing the amorphous precursor at an appropriate temperature due to the atomic level structural optimization.
Brownian relaxation of an inelastic sphere in air

Energy Technology Data Exchange (ETDEWEB)

Bird, G. A., E-mail: gab@gab.com.au [University of Sydney, Sydney, NSW 2006 (Australia)

2016-06-15

The procedures that are used to calculate the forces and moments on an aerodynamic body in the rarefied gas of the upper atmosphere are applied to a small sphere of the size of an aerosol particle at sea level. While the gas-surface interaction model that provides accurate results for macroscopic bodies may not be appropriate for bodies that are comprised of only about a thousand atoms, it provides a limiting case that is more realistic than the elastic model. The paper concentrates on the transfer of energy from the air to an initially stationary sphere as it acquires Brownian motion. Individual particle trajectories vary wildly, but a clear relaxation process emerges from an ensemble average over tens of thousands of trajectories. The translational and rotational energies in equilibrium Brownian motion are determined. Empirical relationships are obtained for the mean translational and rotational relaxation times, the mean initial power input to the particle, the mean rates of energy transfer between the particle and air, and the diffusivity. These relationships are functions of the ratio of the particle mass to an average air molecule mass and the Knudsen number, which is the ratio of the mean free path in the air to the particle diameter. The ratio of the molecular radius to the particle radius also enters as a correction factor. The implications of Brownian relaxation for the second law of thermodynamics are discussed.
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....
Anisotropy and relaxation processes of uniaxially oriented CoFe{sub 2}O{sub 4} nanoparticles dispersed in PDMS

Energy Technology Data Exchange (ETDEWEB)

Antonel, P.S.; Negri, R.M. [Instituto de Quimica Fisica de Materiales, Ambiente y Energia (INQUIMAE), Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon II, Av. Cantilo s/n (1428), Buenos Aires (Argentina); Leyva, A.G. [Grupo de Materia Condensada, Gerencia de Investigacion y Aplicaciones, Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Avda. Gral. Paz 1499 (1650) San Martin, Pcia. de Buenos Aires, Argentina - Escuela de Ciencia y Tecnologia, UNSAM (Argentina); Jorge, G.A., E-mail: gjorge@df.uba.ar [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pabellon I, Av. Cantilo s/n (1428), Buenos Aires (Argentina)

2012-08-15

When a uniaxial magnetic field is applied to a non-magnetic dispersive medium filled with magnetic nanoparticles, they auto-assemble into thin needles parallel to the field direction, due to the strong dipolar interaction among them. We have prepared in this way magnetically oriented nanocomposites of nanometer-size CoFe{sub 2}O{sub 4} particles in a polydimethylsiloxane polymer matrix, with 10% w/w of magnetic particles. We present the characteristic magnetic relaxation curves measured after the application of a magnetic field forming an angle {alpha} with respect to the needle direction. We show that the magnetic viscosity (calculated from the logarithmic relaxation curves) as a function of {alpha} presents a minimum at {alpha}=0, indicating slower relaxation processes associated with this configuration of fields. The results seems to point out that the local magnetic anisotropy of the nanoparticles is oriented along the needles, resulting in the macroscopic magnetic anisotropy observed in our measurements.
Matrix Krylov subspace methods for image restoration

Directory of Open Access Journals (Sweden)

khalide jbilou

2015-09-01

Full Text Available In the present paper, we consider some matrix Krylov subspace methods for solving ill-posed linear matrix equations and in those problems coming from the restoration of blurred and noisy images. Applying the well known Tikhonov regularization procedure leads to a Sylvester matrix equation depending the Tikhonov regularized parameter. We apply the matrix versions of the well known Krylov subspace methods, namely the Least Squared (LSQR and the conjugate gradient (CG methods to get approximate solutions representing the restored images. Some numerical tests are presented to show the effectiveness of the proposed methods.
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.
Modelling of Creep and Stress Relaxation Test of a Polypropylene Microfibre by Using Fraction-Exponential Kernel

Directory of Open Access Journals (Sweden)

Andrea Sorzia

2016-01-01

Full Text Available A tensile test until breakage and a creep and relaxation test on a polypropylene fibre are carried out and the resulting creep and stress relaxation curves are fit by a model adopting a fraction-exponential kernel in the viscoelastic operator. The models using fraction-exponential functions are simpler than the complex ones obtained from combination of dashpots and springs and, furthermore, are suitable for fitting experimental data with good approximation allowing, at the same time, obtaining inverse Laplace transform in closed form. Therefore, the viscoelastic response of polypropylene fibres can be modelled straightforwardly through analytical methods. Addition of polypropylene fibres greatly improves the tensile strength of composite materials with concrete matrix. The proposed analytical model can be employed for simulating the mechanical behaviour of composite materials with embedded viscoelastic fibres.
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
Complex dynamics of memristive circuits: Analytical results and universal slow relaxation

Science.gov (United States)

Caravelli, F.; Traversa, F. L.; Di Ventra, M.

2017-02-01

Networks with memristive elements (resistors with memory) are being explored for a variety of applications ranging from unconventional computing to models of the brain. However, analytical results that highlight the role of the graph connectivity on the memory dynamics are still few, thus limiting our understanding of these important dynamical systems. In this paper, we derive an exact matrix equation of motion that takes into account all the network constraints of a purely memristive circuit, and we employ it to derive analytical results regarding its relaxation properties. We are able to describe the memory evolution in terms of orthogonal projection operators onto the subspace of fundamental loop space of the underlying circuit. This orthogonal projection explicitly reveals the coupling between the spatial and temporal sectors of the memristive circuits and compactly describes the circuit topology. For the case of disordered graphs, we are able to explain the emergence of a power-law relaxation as a superposition of exponential relaxation times with a broad range of scales using random matrices. This power law is also universal, namely independent of the topology of the underlying graph but dependent only on the density of loops. In the case of circuits subject to alternating voltage instead, we are able to obtain an approximate solution of the dynamics, which is tested against a specific network topology. These results suggest a much richer dynamics of memristive networks than previously considered.
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
Ferromagnetic resonance relaxation processes in Zn2Yt

International Nuclear Information System (INIS)

Mita, M.; Shimizu, H.

1975-01-01

Experimentally obtained linewidth in FMR of Zn 2 Y is analyzed numerically on the basis of two-magnon, three-magnon and four-magnon relaxation processes. In the analysis procedure of three-magnon linewidth, the effective exchange constants are determined to be D = 0.15 x 10 -9 Oe cm 2 and D = 9.3 x 10 -9 Oe cm 2 within and between the crystallographic planes. The two-magnon linewidth induced by surface imperfections is discussed in consideration of scattering due to multipole demagnetizations of the imperfections. The four-magnon linewidth is observed for the first time and analyzed successfully
Influence of SiO{sub 2} on conduction and relaxation mechanism of Li{sup +} ions in binary network former lead silicate glasses

Energy Technology Data Exchange (ETDEWEB)

Ahlawat, Navneet [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana (India); Aghamkar, Praveen [Department of Physics, Chaudhary Devi Lal University, Sirsa 125055, Haryana (India); Agarwal, Ashish; Sanghi, Sujata; Sindhu, Monica [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana (India)

2013-04-01

Ion conducting glasses having composition 30Li{sub 2}O·(70−x)PbO·xSiO{sub 2} were prepared by the normal melt quench technique. The compositional variations in density, molar volume and glass transition temperature confirm the dual role of PbO acting as a network modifying oxide as well as a network forming oxide. Conduction and relaxation mechanisms in these glasses were studied using impedance spectroscopy in the frequency range from 1 Hz to 7 MHz and in a temperature range below glass transition temperature. The ac and dc conductivities, activation energy of the dc conductivity and relaxation frequency were extracted from the impedance spectra. Similar values of activation energy for dc conduction and for conductivity relaxation time indicate that the ions have to overcome the same energy barrier while conducting and relaxing. The increase in dc conductivity for silica rich compositions is attributed to the presence of mixed former effect in the studied glasses. The study of conductivity spectra reveals a transition from non-random to random hopping motion of lithium ions on successive replacement of PbO by SiO{sub 2} in glass matrix. The conduction and relaxation mechanism in the studied glasses are well explained with the concept of mismatch and relaxation (CMR) model.
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....
Competition between electronic energy transfer and relaxation in Xe doped Ar and Ne matrices studied by photoelectron spectroscopy

International Nuclear Information System (INIS)

Schwentner, N.; Koch, E.E.

1976-01-01

Thin films of solid Ar and Ne doped with 1% Xe were excited with photons in the energy range from 10 eV to 20 eV in order to measure the energy distribution of the emitted electrons. Binding energies of th host and guest levels are deduced. When host excitons are excited, strong emission of electrons is observed indicating an efficient transfer of the host exciton energy to the Xe guest atoms. The energy of the free excitons is transferred, as can be deduced from the kinetic energy of the photoemitted electrons, rather than the energy of the bound (self-trapped) excitons which are observed in luminescence experiments. Furthermore, there is a striking difference between the Ar and the Ne matrix: In the Ne matrix a fast relaxation from the n = 2 to the n = 1 state was observed and only the energy of the n = 1 exciton is transferred even when higher excitons are excited, in contrast to Ar, where the transferred energy is higher for excitation of the n = 2 excitons than for n = 1. From these observations, time hierarchies for the competition between electronic energy transfer and relaxation are deduced. (orig.) [de
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.
Relaxation and guided imagery do not reduce stress, pain and unpleasantness for 11- to 12-year-old girls during vaccinations.

Science.gov (United States)

Nilsson, Stefan; Forsner, Maria; Finnström, Berit; Mörelius, Evalotte

2015-07-01

Relaxation and guided imagery is a distraction technique known to reduce discomfort during paediatric medical procedures. We examined whether its use decreased the stress experienced by 11- to 12-year-old girls receiving the human papilloma virus vaccination, as well as the intensity and unpleasantness of any pain. A randomised crossover trial was conducted with 37 girls. During the first vaccination, each girl was randomised to receive either relaxation and guided imagery or standard care. They then received the other form of care during the second vaccination. Salivary cortisol was measured before each vaccination, and 30 minutes after it was administered. The girls reported pain intensity and pain unpleasantness before and directly after each vaccination and stress after each vaccination. On a group level, relaxation and guided imagery did not decrease cortisol levels, self-reported stress, pain intensity and pain unpleasantness. Salivary cortisol levels decreased significantly in both groups during the second vaccination. Relaxation and guided imagery did not prove beneficial during the vaccination of 11- to 12-year-old girls and is not recommended as a regular nursing intervention. However, further research is needed into effective techniques to help children who experience pain unpleasantness in connection with needle procedures. ©2015 Foundation Acta Paediatrica. Published by John Wiley & Sons Ltd.

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.
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.
Electric field dependence of the spin relaxation anisotropy in (111) GaAs/AlGaAs quantum wells

International Nuclear Information System (INIS)

Balocchi, A; Amand, T; Renucci, P; Duong, Q H; Marie, X; Wang, G; Liu, B L

2013-01-01

Time-resolved optical spectroscopy experiments in (111)-oriented GaAs/AlGaAs quantum wells (QWs) show a strong electric field dependence of the conduction electron spin relaxation anisotropy. This results from the interplay between the Dresselhaus and Rashba spin splitting in this system with C 3v symmetry. By varying the electric field applied perpendicular to the QW plane from 20 to 50 kV cm −1 the anisotropy of the spin relaxation time parallel (τ s ∥ ) and perpendicular (τ s ⊥ ) to the growth axis can be first canceled and eventually inversed with respect to the one usually observed in III–V zinc-blende QW (τ s ⊥ = 2τ s ∥ ). This dependence stems from the nonlinear contributions of the k-dependent conduction band spin splitting terms which begin to play the dominant spin relaxing role while the linear Dresselhaus terms are compensated by the Rashba ones through the applied bias. A spin density matrix model for the conduction band spin splitting including both linear and cubic terms of the Dresselhaus Hamiltonian is used which allows a quantitative description of the measured electric field dependence of the spin relaxation anisotropy. The existence of an isotropic point where the spin relaxation tensor reduces to a scalar is predicted and confirmed experimentally. The spin splitting compensation electric field and collision processes type in the QW can be likewise directly extracted from the model without complementary measurements. (paper)
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....
Stochastic theory of relaxation and collisional broadening of spectral line shapes

International Nuclear Information System (INIS)

Faid, K.

1986-01-01

A complete stochastic theory of relaxation is developed in terms of a homogeneous equation for the averaged density matrix of a system immersed in a thermal bath. This theory is then used as the basis of a new stochastic approach to the phenomenon of collisional broadening of spectral line shapes. Single-photon and multiphoton processes are studied. The features of a line shape are linked by simple expressions to the statistical properties of a stochastic hermitian Hamiltonian. The ordinary line shape predicted by Kubo's approach is generalized. The present approach predicts broadening as well as asymmetry and shift. A representation of line shapes in multiphoton processes by diagrams is also developed
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....
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.
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, ...
The Effects of Suggestibility on Relaxation.

Science.gov (United States)

Rickard, Henry C.; And Others

1985-01-01

Selected undergraduates (N=32) on the basis of Creative Imagination Scale scores and randomly assigned high and low suggestibility subjects to progressive relaxation (PR) and suggestions of relaxation (SR) training modes. Results revealed a significant pre-post relaxation effect, and main efffects for both suggestibility and training mode. (NRB)
Observation of glassy state relaxation during annealing of frozen sugar solutions by X-ray computed tomography.

Science.gov (United States)

Nakagawa, Kyuya; Tamiya, Shinri; Do, Gabsoo; Kono, Shinji; Ochiai, Takaaki

2018-06-01

Glassy phase formation in a frozen product determines various properties of the freeze-dried products. When an aqueous solution is subjected to freezing, a glassy phase forms as a consequence of freeze-concentration. During post-freezing annealing, the relaxation of the glassy phase and the ripening of ice crystals (i.e. Ostwald ripening) spontaneously occur, where the kinetics are controlled by the annealing and glass transition temperatures. This study was motivated to observe the progress of glassy state relaxation separate from ice coarsening during annealing. X-ray computed tomography (CT) was used to observe a frozen and post-freezing annealed solutions by using monochromatized X-ray from the synchrotron radiation. CT images were successfully obtained, and the frozen matrix were analyzed based on the gray level values that were equivalent to the linear X-ray attenuation coefficients of the observed matters. The CT images obtained from rapidly frozen sucrose and dextrin solutions with different concentrations gave clear linear relationships between the linear X-ray attenuation coefficients values and the solute concentrations. It was confirmed that the glassy state relaxation progressed as increasing annealing time, and this trend was larger in the order of the glass transition temperature of the maximally freeze-concentrated phase. The sucrose-water system required nearly 20 h of annealing time at -5 °C for the completion of the glassy phase relaxation, whereas dextrin-water systems required much longer periods because of their higher glass transition temperatures. The trends of ice coarsening, however, did not perfectly correspond to the trends of the relaxation, suggesting that the glassy phase relaxation and Ostwald ripening would jointly control the ice crystal growth/ripening kinetics, and the dominant mechanism differed by the annealing stage. Copyright © 2018 Elsevier B.V. All rights reserved.
Determination of the magnetic impurities contribution to the nuclear relaxation in metals

International Nuclear Information System (INIS)

Cohen, A.M.

1982-01-01

The renormalization group techniques developed by Wilson for the Kondo problem are applied, for the first time, to the calculation of nuclear spin relaxation rates in dilute magnetic alloys. A procedure that calculates the longitudinal relaxation time T 1 over the entire temperature range 0 B T 1 is derived; for distances R between the impurity and the nucleus large compared to the inverse Fermi momentum H f , the result is identical to Korringa's expression for the nuclear spin relaxation rate in the pure metal. For smaller k F R, T 1 increases and becomes infinite as k F R→0. A numerical approach, capable of calculating T 1 at finite temperatures, is presented and tested by calculating T 1 for T→0; the numerical results are in excellent agreement with the analytical expression discussed above. Only for k F R→ infinity do the results for T 1 at T=0 agree with those found by Roshen and Saam, who recently analysed this problem in the light of Nozieres's Fermi liquid theory. The reasons for the discrepancy for finite k F R are discussed. (author) [pt
The CIFF proof procedure for abductive logic programming with constraints: Theory, implementation and experiments

NARCIS (Netherlands)

Mancarella, P.; Terreni, G.; Sadri, F.; Toni, F.; Endriss, U.

2009-01-01

We present the CIFF proof procedure for abductive logic programming with constraints, and we prove its correctness. CIFF is an extension of the IFF proof procedure for abductive logic programming, relaxing the original restrictions over variable quantification (allowedness conditions) and
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)
Evaluation of PHB/Clay nanocomposite by spin-lattice relaxation time

Directory of Open Access Journals (Sweden)

Mariana Bruno

2008-12-01

Full Text Available Poly(3-hydroxybutyrate (PHB based on nanocomposites containing different amounts of a commercial organically modified clay (viscogel B7 were prepared employing solution intercalation method. Three solvents, such as: CHCl3, dimethylchloride (DMC and tetrahydrofuran (THF were used. The relationship among the processing conditions; molecular structure and intermolecular interaction, between both nanocomposite components, were investigated using a nuclear magnetic resonance (NMR, as a part of characterization methodology, which has been used by Tavares et al. It involves the hydrogen spin-lattice relaxation time, T1H, by solid state nuclear magnetic resonance, employing low field NMR. X ray diffraction was also employed because it is a conventional technique, generally used to obtain the first information on nanocomposite formation. Changes in PHB crystallinity were observed after the organophilic nanoclay had been incorporated in the polymer matrix. These changes, in the microstructure, were detected by the variation of hydrogen nuclear relaxation time values and by X ray, which showed an increase in the clay interlamelar space due to the intercalation of the polymer in the clay between lamellae. It was also observed, for both techniques, that the solvents affect directly the organization of the crystalline region, promoting a better intercalation, considering that they behave like a plasticizer.
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.
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.
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 ...
Relaxation of synchronization on complex networks.

Science.gov (United States)

Son, Seung-Woo; Jeong, Hawoong; Hong, Hyunsuk

2008-07-01

We study collective synchronization in a large number of coupled oscillators on various complex networks. In particular, we focus on the relaxation dynamics of the synchronization, which is important from the viewpoint of information transfer or the dynamics of system recovery from a perturbation. We measure the relaxation time tau that is required to establish global synchronization by varying the structural properties of the networks. It is found that the relaxation time in a strong-coupling regime (K>Kc) logarithmically increases with network size N , which is attributed to the initial random phase fluctuation given by O(N-1/2) . After elimination of the initial-phase fluctuation, the relaxation time is found to be independent of the system size; this implies that the local interaction that depends on the structural connectivity is irrelevant in the relaxation dynamics of the synchronization in the strong-coupling regime. The relaxation dynamics is analytically derived in a form independent of the system size, and it exhibits good consistency with numerical simulations. As an application, we also explore the recovery dynamics of the oscillators when perturbations enter the system.
Evolving fuzzy rules for relaxed-criteria negotiation.

Science.gov (United States)

Sim, Kwang Mong

2008-12-01

In the literature on automated negotiation, very few negotiation agents are designed with the flexibility to slightly relax their negotiation criteria to reach a consensus more rapidly and with more certainty. Furthermore, these relaxed-criteria negotiation agents were not equipped with the ability to enhance their performance by learning and evolving their relaxed-criteria negotiation rules. The impetus of this work is designing market-driven negotiation agents (MDAs) that not only have the flexibility of relaxing bargaining criteria using fuzzy rules, but can also evolve their structures by learning new relaxed-criteria fuzzy rules to improve their negotiation outcomes as they participate in negotiations in more e-markets. To this end, an evolutionary algorithm for adapting and evolving relaxed-criteria fuzzy rules was developed. Implementing the idea in a testbed, two kinds of experiments for evaluating and comparing EvEMDAs (MDAs with relaxed-criteria rules that are evolved using the evolutionary algorithm) and EMDAs (MDAs with relaxed-criteria rules that are manually constructed) were carried out through stochastic simulations. Empirical results show that: 1) EvEMDAs generally outperformed EMDAs in different types of e-markets and 2) the negotiation outcomes of EvEMDAs generally improved as they negotiated in more e-markets.
Quantitative evaluation of polymer concentration profile during swelling of hydrophilic matrix tablets using 1H NMR and MRI methods.

Science.gov (United States)

Baumgartner, Sasa; Lahajnar, Gojmir; Sepe, Ana; Kristl, Julijana

2005-02-01

Many pharmaceutical tablets are based on hydrophilic polymers, which, after exposure to water, form a gel layer around the tablet that limits the dissolution and diffusion of the drug and provides a mechanism for controlled drug release. Our aim was to determine the thickness of the swollen gel layer of matrix tablets and to develop a method for calculating the polymer concentration profile across the gel layer. MR imaging has been used to investigate the in situ swelling behaviour of cellulose ether matrix tablets and NMR spectroscopy experiments were performed on homogeneous hydrogels with known polymer concentration. The MRI results show that the thickest gel layer was observed for hydroxyethylcellulose tablets, followed by definitely thinner but almost equal gel layer for hydroxypropylcellulose and hydroxypropylmethylcellulose of both molecular weights. The water proton NMR relaxation parameters were combined with the MRI data to obtain a quantitative description of the swelling process on the basis of the concentrations and mobilities of water and polymer as functions of time and distance. The different concentration profiles observed after the same swelling time are the consequence of the different polymer characteristics. The procedure developed here could be used as a general method for calculating polymer concentration profiles on other similar polymeric systems.

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
Numerical solution of quadratic matrix equations for free vibration analysis of structures

Science.gov (United States)

Gupta, K. K.

1975-01-01

This paper is concerned with the efficient and accurate solution of the eigenvalue problem represented by quadratic matrix equations. Such matrix forms are obtained in connection with the free vibration analysis of structures, discretized by finite 'dynamic' elements, resulting in frequency-dependent stiffness and inertia matrices. The paper presents a new numerical solution procedure of the quadratic matrix equations, based on a combined Sturm sequence and inverse iteration technique enabling economical and accurate determination of a few required eigenvalues and associated vectors. An alternative procedure based on a simultaneous iteration procedure is also described when only the first few modes are the usual requirement. The employment of finite dynamic elements in conjunction with the presently developed eigenvalue routines results in a most significant economy in the dynamic analysis of structures.
Quantum Stochastic Trajectories: The Fokker-Planck-Bohm Equation Driven by the Reduced Density Matrix.

Science.gov (United States)

Avanzini, Francesco; Moro, Giorgio J

2018-03-15

The quantum molecular trajectory is the deterministic trajectory, arising from the Bohm theory, that describes the instantaneous positions of the nuclei of molecules by assuring the agreement with the predictions of quantum mechanics. Therefore, it provides the suitable framework for representing the geometry and the motions of molecules without neglecting their quantum nature. However, the quantum molecular trajectory is extremely demanding from the computational point of view, and this strongly limits its applications. To overcome such a drawback, we derive a stochastic representation of the quantum molecular trajectory, through projection operator techniques, for the degrees of freedom of an open quantum system. The resulting Fokker-Planck operator is parametrically dependent upon the reduced density matrix of the open system. Because of the pilot role played by the reduced density matrix, this stochastic approach is able to represent accurately the main features of the open system motions both at equilibrium and out of equilibrium with the environment. To verify this procedure, the predictions of the stochastic and deterministic representation are compared for a model system of six interacting harmonic oscillators, where one oscillator is taken as the open quantum system of interest. The undeniable advantage of the stochastic approach is that of providing a simplified and self-contained representation of the dynamics of the open system coordinates. Furthermore, it can be employed to study the out of equilibrium dynamics and the relaxation of quantum molecular motions during photoinduced processes, like photoinduced conformational changes and proton transfers.
Estimating side-chain order in methyl-protonated, perdeuterated proteins via multiple-quantum relaxation violated coherence transfer NMR spectroscopy

International Nuclear Information System (INIS)

Sun Hechao; Godoy-Ruiz, Raquel; Tugarinov, Vitali

2012-01-01

Relaxation violated coherence transfer NMR spectroscopy (Tugarinov et al. in J Am Chem Soc 129:1743–1750, 2007) is an established experimental tool for quantitative estimation of the amplitudes of side-chain motions in methyl-protonated, highly deuterated proteins. Relaxation violated coherence transfer experiments monitor the build-up of methyl proton multiple-quantum coherences that can be created in magnetically equivalent spin-systems as long as their transverse magnetization components relax with substantially different rates. The rate of this build-up is a reporter of the methyl-bearing side-chain mobility. Although the build-up of multiple-quantum 1 H coherences is monitored in these experiments, the decay of the methyl signal during relaxation delays occurs when methyl proton magnetization is in a single-quantum state. We describe a relaxation violated coherence transfer approach where the relaxation of multiple-quantum 1 H– 13 C methyl coherences during the relaxation delay period is quantified. The NMR experiment and the associated fitting procedure that models the time-dependence of the signal build-up, are applicable to the characterization of side-chain order in [ 13 CH 3 ]-methyl-labeled, highly deuterated protein systems up to ∼100 kDa in molecular weight. The feasibility of extracting reliable measures of side-chain order is experimentally verified on methyl-protonated, perdeuterated samples of an 8.5-kDa ubiquitin at 10°C and an 82-kDa Malate Synthase G at 37°C.
Momentum constraint relaxation

International Nuclear Information System (INIS)

Marronetti, Pedro

2006-01-01

Full relativistic simulations in three dimensions invariably develop runaway modes that grow exponentially and are accompanied by violations of the Hamiltonian and momentum constraints. Recently, we introduced a numerical method (Hamiltonian relaxation) that greatly reduces the Hamiltonian constraint violation and helps improve the quality of the numerical model. We present here a method that controls the violation of the momentum constraint. The method is based on the addition of a longitudinal component to the traceless extrinsic curvature A ij -tilde, generated by a vector potential w i , as outlined by York. The components of w i are relaxed to solve approximately the momentum constraint equations, slowly pushing the evolution towards the space of solutions of the constraint equations. We test this method with simulations of binary neutron stars in circular orbits and show that it effectively controls the growth of the aforementioned violations. We also show that a full numerical enforcement of the constraints, as opposed to the gentle correction of the momentum relaxation scheme, results in the development of instabilities that stop the runs shortly
Toward structural dynamics: protein motions viewed by chemical shift modulations and direct detection of C'N multiple-quantum relaxation.

Science.gov (United States)

Mori, Mirko; Kateb, Fatiha; Bodenhausen, Geoffrey; Piccioli, Mario; Abergel, Daniel

2010-03-17

Multiple quantum relaxation in proteins reveals unexpected relationships between correlated or anti-correlated conformational backbone dynamics in alpha-helices or beta-sheets. The contributions of conformational exchange to the relaxation rates of C'N coherences (i.e., double- and zero-quantum coherences involving backbone carbonyl (13)C' and neighboring amide (15)N nuclei) depend on the kinetics of slow exchange processes, as well as on the populations of the conformations and chemical shift differences of (13)C' and (15)N nuclei. The relaxation rates of C'N coherences, which reflect concerted fluctuations due to slow chemical shift modulations (CSMs), were determined by direct (13)C detection in diamagnetic and paramagnetic proteins. In well-folded proteins such as lanthanide-substituted calbindin (CaLnCb), copper,zinc superoxide dismutase (Cu,Zn SOD), and matrix metalloproteinase (MMP12), slow conformational exchange occurs along the entire backbone. Our observations demonstrate that relaxation rates of C'N coherences arising from slow backbone dynamics have positive signs (characteristic of correlated fluctuations) in beta-sheets and negative signs (characteristic of anti-correlated fluctuations) in alpha-helices. This extends the prospects of structure-dynamics relationships to slow time scales that are relevant for protein function and enzymatic activity.
Mechanical spectroscopy of thermal stress relaxation in aluminium alloys reinforced with short alumina fibres

Energy Technology Data Exchange (ETDEWEB)

Carreno-Morelli, E.; Schaller, R. [Ecole Polytechnique Federale, Lausanne (Switzerland). Inst. de Genie Atomique; Urreta, S.E.

1998-05-01

The mechanical behaviour under low temperature thermal cycling of aluminium-based composites reinforced with short Al{sub 2}O{sub 3} SAFFIL fibres has been investigated by mechanical spectroscopy (mechanical loss and elastic shear modulus measurements). A mechanical loss maximum has been observed during cooling which originates in the relaxation of thermal stresses at the interfaces due to the differential thermal expansion between matrix and reinforcement. The maximum height increases with the volumetric fibre content. In addition, if the matrix strength is increased by the appropriated choice of alloy and thermal treatment, the maximum diminishes and shifts to lower temperatures. No damage accumulation at the interfaces has been detected during long period thermal cycling in the range 100 to 500 K. A description of the damping behaviour is made in terms of the development of microplastic zones which surround the fibres. (orig.) 9 refs.
Thermodynamic scaling of α-relaxation time and viscosity stems from the Johari-Goldstein β-relaxation or the primitive relaxation of the coupling model.

Science.gov (United States)

Ngai, K L; Habasaki, J; Prevosto, D; Capaccioli, S; Paluch, Marian

2012-07-21

By now it is well established that the structural α-relaxation time, τ(α), of non-associated small molecular and polymeric glass-formers obey thermodynamic scaling. In other words, τ(α) is a function Φ of the product variable, ρ(γ)/T, where ρ is the density and T the temperature. The constant γ as well as the function, τ(α) = Φ(ρ(γ)/T), is material dependent. Actually this dependence of τ(α) on ρ(γ)/T originates from the dependence on the same product variable of the Johari-Goldstein β-relaxation time, τ(β), or the primitive relaxation time, τ(0), of the coupling model. To support this assertion, we give evidences from various sources itemized as follows. (1) The invariance of the relation between τ(α) and τ(β) or τ(0) to widely different combinations of pressure and temperature. (2) Experimental dielectric and viscosity data of glass-forming van der Waals liquids and polymer. (3) Molecular dynamics simulations of binary Lennard-Jones (LJ) models, the Lewis-Wahnström model of ortho-terphenyl, 1,4 polybutadiene, a room temperature ionic liquid, 1-ethyl-3-methylimidazolium nitrate, and a molten salt 2Ca(NO(3))(2)·3KNO(3) (CKN). (4) Both diffusivity and structural relaxation time, as well as the breakdown of Stokes-Einstein relation in CKN obey thermodynamic scaling by ρ(γ)/T with the same γ. (5) In polymers, the chain normal mode relaxation time, τ(N), is another function of ρ(γ)/T with the same γ as segmental relaxation time τ(α). (6) While the data of τ(α) from simulations for the full LJ binary mixture obey very well the thermodynamic scaling, it is strongly violated when the LJ interaction potential is truncated beyond typical inter-particle distance, although in both cases the repulsive pair potentials coincide for some distances.
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)
Muscle relaxation for individuals having tattoos removed through laser treatment: possible effects regarding anxiety and pain.

Science.gov (United States)

Huang, Faye; Chou, Wen-Jiun; Chen, Tien-Hsing; Chen, Ching; Hsieh, Yu-Lian; Chong, Mian-Yoon; Hung, Chi-Fa; Lin, Shu-Ching; Tsai, Hsiu-Huang; Wang, Liang-Jen

2016-08-01

Effectively managing pain is vital for the well-being and satisfaction of patients undergoing dermatologic treatments involving lasers. This study investigates the potential outcome of using muscle relaxation techniques to reduce pain among people having their tattoos removed with laser treatment. This study consists of 56 participants (mean age 18.1 ± 2.1 years) that had tattoos removed using the principle of selective photothermolysis. These participants underwent muscle relaxation before receiving the laser treatment. Their peripheral skin temperatures (PST) were measured both at the beginning and the end of the muscle relaxation period. Then, the Beck Anxiety Inventory was applied to evaluate anxiety levels. Once the laser treatment was completed, pain levels were measured using a visual analogue scale. A total of 125 person-sessions of laser treatment and psychometric assessments were performed in this study. The muscle relaxation method significantly increased the PST of the participants while reducing the levels of anxiety and pain throughout the course of the laser treatment procedure. The PST, anxiety scores, and pain scores all showed significant correlations with one another. According to the results obtained, this study proposes that muscle relaxation techniques be considered possibly auxiliary treatment options for individuals having tattoos removed through laser treatment. Additional studies with a comparison group and a larger sample size are required in the future to confirm the effectiveness of such intervention.
Viscoelastic sliding and diffusive relaxation along grain boundaries in polycrystalline boron nitride

International Nuclear Information System (INIS)

Pezzotti, G.; Nishida, Toshihiko; Kleebe, H.J.; Ota, Kenichi

1997-01-01

Dense hexagonal boron nitride (BN) materials were prepared via two different processing routes: (1) hot-pressing with the addition of a Ca/B-containing glass and (2) chemical vapor deposition (CVD). The resulting microstructure of both materials was studied by scanning and transmission electron microscopy. While the hot-pressed BN material shows, apart from large BN matrix grains, an inhomogeneous distribution of residual glass at room temperature, the CVD deposition yields a homogeneous fine grained microstructure with no amorphous residue detectable. Internal-friction experiments were performed to study the micromechanical response of the materials when exposed to high temperatures. The CVD material revealed no relaxation peak during testing up to 2,300 C, while the glass-doped sample showed a pronounced relaxation peak at a peak-top temperature of about 600 C. This temperature corresponds to the softening temperature known for bulk Ca/B-glasses and it is, therefore, concluded that the glass homogeneously wets the BN grains at elevated temperatures. The results presented are seen as the first clear evidence that the internal friction peak monitored for various glass-containing ceramics is indeed related to a viscous sliding process along grain boundaries
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
On aggregation of relaxed T-indistinguishability operators

Energy Technology Data Exchange (ETDEWEB)

Fuster-Parra, P.

2017-07-01

The notion of T -indistinguishability operator was introduced by E. Trillas in [7] with the aim of fuzzifying the classical (crisp) notion of equivalence relation. Relaxed metrics and indistinguishability operators are closely related. Indeed, in [1] it has been stated that the logical counterpart for relaxed metrics is, in some sense, a generalized indistinguishability operator (relaxed T -indistinguishability operator). Notice that the notion of T -indistinguishability operator is retrieved as a particular case of relaxed T -indistinguishability operator whenever the relaxed T - indistinguishability operator satisfies also the reflexivity. In fact, a relaxed indistinguishability operator is a indistinguishability operator if and only if it holds the reflexivity. The same occurs when we consider T -indistinguishability operator that separates points. Several authors have studied the aggregation of some classes of fuzzy relations (see [3, 4, 5, 6]), where it is stated that transitivity is one of the most important properties of a fuzzy relation. In [5] a study of aggregation of T-indistinguishability operators is presented, motivated by this work the aim of this study is to analyze the case of aggregating relaxed T-indistinguishability operators. (Author)
Nuclear spin-lattice relaxation in carbon nanostructures

Energy Technology Data Exchange (ETDEWEB)

Panich, A.M., E-mail: pan@bgu.ac.i [Department of Physics, Ben-Gurion University of the Negev, P.O. Box 653, Beer Sheva 84105 (Israel); Sergeev, N.A. [Institute of Physics, University of Szczecin, 70-451 Szczecin (Poland)

2010-04-15

Interpretation of nuclear spin-lattice relaxation data in the carbon nanostructures is usually based on the analysis of fluctuations of dipole-dipole interactions of nuclear spins and anisotropic electron-nuclear interactions responsible for chemical shielding, which are caused by molecular dynamics. However, many nanocarbon systems such as fullerene and nanotube derivatives, nanodiamonds and carbon onions reveal noticeable amount of paramagnetic defects with unpaired electrons originating from dangling bonds. The interaction between nuclear and electron spins strongly influences the nuclear spin-lattice relaxation, but usually is not taken into account, thus the relaxation data are not correctly interpreted. Here we report on the temperature dependent NMR spectra and spin-lattice relaxation measurements of intercalated fullerenes C{sub 60}(MF{sub 6}){sub 2} (M=As and Sb), where nuclear relaxation is caused by both molecular rotation and interaction between nuclei and unpaired electron spins. We present a detailed theoretical analysis of the spin-lattice relaxation data taking into account both these contributions. Good agreement between the experimental data and calculations is obtained. The developed approach would be useful in interpreting the NMR relaxation data in different nanostructures and their intercalation compounds.
Multiple Speech Source Separation Using Inter-Channel Correlation and Relaxed Sparsity

Directory of Open Access Journals (Sweden)

Maoshen Jia

2018-01-01

Full Text Available In this work, a multiple speech source separation method using inter-channel correlation and relaxed sparsity is proposed. A B-format microphone with four spatially located channels is adopted due to the size of the microphone array to preserve the spatial parameter integrity of the original signal. Specifically, we firstly measure the proportion of overlapped components among multiple sources and find that there exist many overlapped time-frequency (TF components with increasing source number. Then, considering the relaxed sparsity of speech sources, we propose a dynamic threshold-based separation approach of sparse components where the threshold is determined by the inter-channel correlation among the recording signals. After conducting a statistical analysis of the number of active sources at each TF instant, a form of relaxed sparsity called the half-K assumption is proposed so that the active source number in a certain TF bin does not exceed half the total number of simultaneously occurring sources. By applying the half-K assumption, the non-sparse components are recovered by regarding the extracted sparse components as a guide, combined with vector decomposition and matrix factorization. Eventually, the final TF coefficients of each source are recovered by the synthesis of sparse and non-sparse components. The proposed method has been evaluated using up to six simultaneous speech sources under both anechoic and reverberant conditions. Both objective and subjective evaluations validated that the perceptual quality of the separated speech by the proposed approach outperforms existing blind source separation (BSS approaches. Besides, it is robust to different speeches whilst confirming all the separated speeches with similar perceptual quality.
A procedure for searching the equilibrium core of a research reactor

International Nuclear Information System (INIS)

Bakri Arbie; Liem Peng Hong; Prayoto

1996-01-01

A procedure for searching the equilibrium core of a research reactor has been proposed. The searching procedure is based on the relaxation method and has been implemented in Batan-EQUIL-2D in-core fuel management code. The few-group neutron diffusion theory in 2-D, X-Y, and R-Z reactor geometries are adopted as the framework of the code. The successful applicability of the procedure for obtaining the new RSG-GAS (MPR-30) silicide equilibrium core was shown. (author)
[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
An alternative approach to KP hierarchy in matrix models

International Nuclear Information System (INIS)

Bonora, L.; Xiong, C.S.

1992-01-01

We show that there exists an alternative procedure in order to extract differential hierarchies, such as the KdV hierarchy, from one-matrix models, without taking a continuum limit. To prove this we introduce the Toda lattice and reformulate it in operator form. We then consider the reduction to the systems appropriate for a one-matrix model. (orig.)
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
Use of relaxation skills in differentially skilled athletes.

OpenAIRE

Kudlackova, K.; Eccles, D. W.; Dieffenbach, K.

2013-01-01

Objectives: To examine the use of relaxation skills by differentially skilled athletes in relation to the deliberate practice framework. Design: Differentially skilled athletes completed a survey about their use of relaxation skills. Method: 150 athletes representing three skill levels (recreational, college, and professional) completed the deliberate relaxation for sport survey, which assessed relaxation on three deliberate practice dimensions (relevancy, concentration, and ...

Hyperfine relaxation of an optically pumped cesium vapor

International Nuclear Information System (INIS)

Tornos, J.; Amare, J.C.

1986-01-01

The relaxation of hyperfine orientation indirectly induced by optical pumping with a σ-polarized D 1 -light in a cesium vapor in the presence of Ar is experimentally studied. The detection technique ensures the absence of quadrupole relaxation contributions in the relaxation signals. The results from the dependences of the hyperfine relaxation rate on the temperature and argon pressure are: diffusion coefficient of Cs in Ar, D 0 = 0.101 +- 0.010 cm 2 s -1 at 0 0 C and 760 Torr; relaxation cross section by Cs-Ar collisions, σ/sub c/ = (104 +- 5) x 10 -23 cm 2 ; relaxation cross section by Cs-Cs (spin exchange) collisions, σ/sub e//sub x/ = (1.63 +- 0.13) x 10 -14 cm 2
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
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.
Relaxation properties in classical diamagnetism

Science.gov (United States)

Carati, A.; Benfenati, F.; Galgani, L.

2011-06-01

It is an old result of Bohr that, according to classical statistical mechanics, at equilibrium a system of electrons in a static magnetic field presents no magnetization. Thus a magnetization can occur only in an out of equilibrium state, such as that produced through the Foucault currents when a magnetic field is switched on. It was suggested by Bohr that, after the establishment of such a nonequilibrium state, the system of electrons would quickly relax back to equilibrium. In the present paper, we study numerically the relaxation to equilibrium in a modified Bohr model, which is mathematically equivalent to a billiard with obstacles, immersed in a magnetic field that is adiabatically switched on. We show that it is not guaranteed that equilibrium is attained within the typical time scales of microscopic dynamics. Depending on the values of the parameters, one has a relaxation either to equilibrium or to a diamagnetic (presumably metastable) state. The analogy with the relaxation properties in the Fermi Pasta Ulam problem is also pointed out.
Measuring order in disordered systems and disorder in ordered systems: Random matrix theory for isotropic and nematic liquid crystals and its perspective on pseudo-nematic domains

Science.gov (United States)

Zhao, Yan; Stratt, Richard M.

2018-05-01

Surprisingly long-ranged intermolecular correlations begin to appear in isotropic (orientationally disordered) phases of liquid crystal forming molecules when the temperature or density starts to close in on the boundary with the nematic (ordered) phase. Indeed, the presence of slowly relaxing, strongly orientationally correlated, sets of molecules under putatively disordered conditions ("pseudo-nematic domains") has been apparent for some time from light-scattering and optical-Kerr experiments. Still, a fully microscopic characterization of these domains has been lacking. We illustrate in this paper how pseudo-nematic domains can be studied in even relatively small computer simulations by looking for order-parameter tensor fluctuations much larger than one would expect from random matrix theory. To develop this idea, we show that random matrix theory offers an exact description of how the probability distribution for liquid-crystal order parameter tensors converges to its macroscopic-system limit. We then illustrate how domain properties can be inferred from finite-size-induced deviations from these random matrix predictions. A straightforward generalization of time-independent random matrix theory also allows us to prove that the analogous random matrix predictions for the time dependence of the order-parameter tensor are similarly exact in the macroscopic limit, and that relaxation behavior of the domains can be seen in the breakdown of the finite-size scaling required by that random-matrix theory.
Angular-contact ball-bearing internal load estimation algorithm using runtime adaptive relaxation

Science.gov (United States)

Medina, H.; Mutu, R.

2017-07-01

An algorithm to estimate internal loads for single-row angular contact ball bearings due to externally applied thrust loads and high-operating speeds is presented. A new runtime adaptive relaxation procedure and blending function is proposed which ensures algorithm stability whilst also reducing the number of iterations needed to reach convergence, leading to an average reduction in computation time in excess of approximately 80%. The model is validated based on a 218 angular contact bearing and shows excellent agreement compared to published results.
Relaxation Techniques to Manage IBS Symptoms

Science.gov (United States)

... for 15–20 seconds and then begin again. Progressive Muscle Relaxation This method of relaxation focuses on ... helpful, please consider supporting IFFGD with a small tax- deductible donation. Make Donation Adapted from IFFGD Publication # ...
Universal divergenceless scaling between structural relaxation and caged dynamics in glass-forming systems.

Science.gov (United States)

Ottochian, A; De Michele, C; Leporini, D

2009-12-14

On approaching the glass transition, the microscopic kinetic unit spends increasing time rattling in the cage of the first neighbors, whereas its average escape time, the structural relaxation time tau(alpha), increases from a few picoseconds up to thousands of seconds. A thorough study of the correlation between tau(alpha) and the rattling amplitude, expressed by the Debye-Waller factor, was carried out. Molecular-dynamics simulations of both a model polymer system and a binary mixture were performed by varying the temperature, the density rho, the potential and the polymer length to consider the structural relaxation as well as both the rotational and the translation diffusion. The present simulations, together with MD studies on other glassformers, evidence the scaling between the structural relaxation and the caged dynamics. An analytic model of the master curve is developed in terms of two characteristic length scales a(2) (1/2) and sigma(a(2) ) (1/2), pertaining to the distance to be covered by the kinetic unit to reach a transition state. The model does not imply tau(alpha) divergences. The comparison with the experiments supports the numerical evidence over a range of relaxation times as wide as about eighteen orders of magnitude. A comparison with other scaling and correlation procedures is presented. In particular, the density scaling of the length scales a(2) (1/2), sigma(a(2) ) (1/2) proportional to rho(-1/3) is shown to be not supported by the present simulations. The study suggests that the equilibrium and the moderately supercooled states of the glassformers possess key information on the huge slowing-down of their relaxation close to the glass transition. The latter, according to the present simulations, exhibits features consistent with the Lindemann melting criterion and the free-volume model.
Vibrational and Rotational Energy Relaxation in Liquids

DEFF Research Database (Denmark)

Petersen, Jakob

Vibrational and rotational energy relaxation in liquids are studied by means of computer simulations. As a precursor for studying vibrational energy relaxation of a solute molecule subsequent to the formation of a chemical bond, the validity of the classical Bersohn-Zewail model for describing......, the vibrational energy relaxation of I2 subsequent to photodissociation and recombination in CCl4 is studied using classical Molecular Dynamics simulations. The vibrational relaxation times and the time-dependent I-I pair distribution function are compared to new experimental results, and a qualitative agreement...... is found in both cases. Furthermore, the rotational energy relaxation of H2O in liquid water is studied via simulations and a power-and-work analysis. The mechanism of the energy transfer from the rotationally excited H2O molecule to its water neighbors is elucidated, i.e. the energy-accepting degrees...
Interstitial relaxations due to hydrostatic stress in niobium--oxygen alloys

International Nuclear Information System (INIS)

Tewari, S.N.

1974-01-01

Experimental investigations of the anelastic relaxation induced by hydrostatic stress in the range from ambient to 81 ksi were made for niobium--oxygen alloys. The anelastic responses, both for the pressurization and the pressure release experiments, were followed by measuring the relative length change between the oxygenated niobium sample and a pure niobium frame with a precision of about 2 A. The relaxation spectrum observed was shown to be made up of three distinct relaxations with unique relaxation times and strengths. The pressure dependence of the relaxation times gave the apparent activation volume for these relaxations of the order of 4 cm 3 /mole. The relaxations were observed to have relaxation strengths of the order of 10 -4 which were found to be independent of pressure up to 81 ksi. The relaxation times for these relaxations were found to occur in the same general temperature range as those for the Snoek relaxations of oxygen clusters in niobium. The temperature dependence of the relaxation times, however, gave activation energies of about 11 to 15 kcal/mole, as compared with roughly 27 to 29 kcal/mole for the Snoek relaxation of oxygen clusters in niobium. Several possible models for these relaxations were developed, however, none could predict the observed temperature dependence. The best interpretation of the data is that due to some anomalous competing relaxation the actual temperature dependence of these relaxations could not be observed. A completely self-consistent analysis is found which is based upon this assumption. (U.S.)
Relaxed Bell inequalities and Kochen-Specker theorems

Energy Technology Data Exchange (ETDEWEB)

Hall, Michael J. W. [Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200 (Australia)

2011-08-15

The combination of various physically plausible properties, such as no signaling, determinism, and experimental free will, is known to be incompatible with quantum correlations. Hence, these properties must be individually or jointly relaxed in any model of such correlations. The necessary degrees of relaxation are quantified here via natural distance and information-theoretic measures. This allows quantitative comparisons between different models in terms of the resources, such as the number of bits of randomness, communication, and/or correlation, that they require. For example, measurement dependence is a relatively strong resource for modeling singlet-state correlations, with only 1/15 of one bit of correlation required between measurement settings and the underlying variable. It is shown how various ''relaxed'' Bell inequalities may be obtained, which precisely specify the complementary degrees of relaxation required to model any given violation of a standard Bell inequality. The robustness of a class of Kochen-Specker theorems, to relaxation of measurement independence, is also investigated. It is shown that a theorem of Mermin remains valid unless measurement independence is relaxed by 1/3. The Conway-Kochen ''free will'' theorem and a result of Hardy are less robust, failing if measurement independence is relaxed by only 6.5% and 4.5%, respectively. An appendix shows that existence of an outcome-independent model is equivalent to existence of a deterministic model.
Long-persistent relaxation and frozen conductivity in Zn Se with radiation-induced defects

International Nuclear Information System (INIS)

Blajcu, A.I.; Djuadi, D.; Casian, V.A.; Moseiciuc, G.S.; Nedeoglo, D.D.

1993-01-01

In an n-Zn Se crystals which have been preliminarily annealed in liquid Zn and then exposed to irradiation by a flow of electrons with an energy of E = 1.3 MeV and a dose of irradiation from 2.73 x 10 16 to 5.19 x 10 17 el/cm 2 , phenomena of a long-persistent conductivity relaxation (LCR) and frozen conduction (FC) at 77 K have been brought out and examined. It has been shown that the character of the relaxation processes at small doses of irradiation is rather well explained by the two-barrier model of an inhomogeneous semiconductor which represents a low-resistance matrix with high-resistance inclusions (clusters). As the dose of irradiation increases the overlapping of regions of space charge which surrounds the high-resistance inclusions increases and the considered model of high-resistance inclusions must be changed at D = 3 x 10 17 el/cm 2 into of a random potential relief. The temperature quenching of FC is explain in the assumption that, with the temperature increase, the drift and the recombination barriers decrease simultaneously as the result of variation of the sizes of space charge region surrounding the clusters. (Author)
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.
Residual stresses and mechanical properties of metal matrix composites

International Nuclear Information System (INIS)

Persson, Christer.

1993-01-01

The large difference in coefficient of thermal expansion of the matrix and particles in a metal matrix composite will introduce residual stresses during cooling from process temperature. These stresses are locally very high, and are known to influence the mechanical behaviour of the material. Changes in the stress state will occur during heat treatments and when the material is loaded due to different elastic, plastic, and creep properties of the constituents. The change of residual stresses in an Al-SiC particulate composite after different degree of plastic straining has been studied. The effect of plastic straining was modelled by an Eshelby model. The model and the measurements both show that the stress in the loading direction decreases for a tensile plastic strain and increases for a compressive plastic strain. By x-ray diffraction the stress response in the matrix and particles can be measured independently. This has been used to determine the stress state under and after heat treatments and under mechanical loading in two Al 15% SiC metal matrix composites. By analysing the line width from x-ray experiment the changes in the microstrains in the material were studied. A finite element model was used to model the generation of thermal residual stresses, stress relaxation during heat treatments, and load sharing during the first load cycle. Calculated stresses and microstrains were found to be in good agreement with the measured values. The elastic behaviour of the composite can be understood largely in terms of elastic load transfer between matrix and particles. However, at higher loads when the matrix becomes plastic residual stresses also become important. 21 refs
Cross-relaxation in multiple pulse NQR spin-locking

Energy Technology Data Exchange (ETDEWEB)

Beltjukov, P. A.; Kibrik, G. E. [Perm State University, Physics Department (Russian Federation); Furman, G. B., E-mail: gregoryf@bgu.ac.il; Goren, S. D. [Ben Gurion University, Physics Department (Israel)

2008-01-15

The experimental and theoretical NQR multiple-pulse spin locking study of cross-relaxation process in solids containing nuclei of two different sorts I > 1/2 and S = 1/2 coupled by the dipole-dipole interactions and influenced by an external magnetic field. Two coupled equations for the inverse spin temperatures of the both spin systems describing the mutual spin lattice relaxation and the cross-relaxation were obtained using the method of the nonequilibrium state operator. It is shown that the relaxation process is realized with non-exponential time dependence describing by a sum of two exponents. The cross relaxation time is calculated as a function of the multiple-pulse field parameters which agree with the experimental data. The calculated magnetization cross relaxation time vs the strength of the applied magnetic field agrees well with the obtained experimental data.
Collisional relaxation of electron tail distribution

International Nuclear Information System (INIS)

Yamagiwa, Mitsuru; Okamoto, Masao.

1985-05-01

Relaxation due to the Coulomb collisions of the electron velocity distribution function with a high energy tail is investigated in detail. In the course of the relaxation, a 'saddle' point can be created in velocity space owing to upsilon -3 dependence of the deflection rate and a positive slope or a 'dip' appears in the tail direction. The time evolution of the electron tail is studied analytically. A comparison is made with numerical results by using a Fokker-Planck code. Also discussed is the kinetic instability concerned with the positive slope during the relaxation. (author)
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.
Influence of cold rolling and fatigue on the residual stress state of a metal matrix composite

International Nuclear Information System (INIS)

Hanus, E.; Ericsson, T.; Lu, J.; Decomps, F.

1993-01-01

The large difference in the coefficient of thermal expansion between the matrix alloy and the particle in a metal matrix composite gives rise to residual stresses in the material. In the present work the effect of cold rolling and four-point bending fatigue on the residual stress state of a silicon carbide particle reinforced aluminium alloy (AA 2014) has been investigated. The three dimensional stress state measured in both phases: matrix and reinforcement, has been determined by using an X-ray diffraction technique. It was found that cold rolling induces surface compressive macrostresses of about -250 MPa, with a penetration depth around 2 mm. The absolute values of the pseudomacrostresses in both phases are significantly reduced due to the single track rolling. Stress relaxation occurs during four-point bending fatigue. (orig.)
A matrix formulation of Frobenius power series solutions using products of 4X4 matrices

Directory of Open Access Journals (Sweden)

Jeremy Mandelkern

2015-08-01

Full Text Available In Coddington and Levison [7, p. 119, Thm. 4.1] and Balser [4, p. 18-19, Thm. 5], matrix formulations of Frobenius theory, near a regular singular point, are given using 2X2 matrix recurrence relations yielding fundamental matrices consisting of two linearly independent solutions together with their quasi-derivatives. In this article we apply a reformulation of these matrix methods to the Bessel equation of nonintegral order. The reformulated approach of this article differs from [7] and [4] by its implementation of a new ``vectorization'' procedure that yields recurrence relations of an altogether different form: namely, it replaces the implicit 2X2 matrix recurrence relations of both [7] and [4] by explicit 4X4 matrix recurrence relations that are implemented by means only of 4X4 matrix products. This new idea of using a vectorization procedure may further enable the development of symbolic manipulator programs for matrix forms of the Frobenius theory.
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

Microlocal study of S-matrix singularity structure

International Nuclear Information System (INIS)

Kawai, Takahiro; Kyoto Univ.; Stapp, H.P.

1975-01-01

Support is adduced for two related conjectures of simplicity of the analytic structure of the S-matrix and related function; namely, Sato's conjecture that the S-matrix is a solution of a maximally over-determined system of pseudo-differential equations, and our conjecture that the singularity spectrum of any bubble diagram function has the conormal structure with respect to a canonical decomposition of the solutions of the relevant Landau equations. This latter conjecture eliminates the open sets of allowed singularities that existing procedures permit. (orig.) [de
Interplay of domain walls and magnetization rotation on dynamic magnetization process in iron/polymer–matrix soft magnetic composites

Energy Technology Data Exchange (ETDEWEB)

Dobák, Samuel, E-mail: samuel.dobak@student.upjs.sk [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Füzer, Ján; Kollár, Peter [Institute of Physics, Faculty of Science, Pavol Jozef Šafárik University, Park Angelinum 9, 041 54 Košice (Slovakia); Fáberová, Mária; Bureš, Radovan [Institute of Materials Research, Slovak Academy of Sciences, Watsonova 47, 043 53 Košice (Slovakia)

2017-03-15

This study sheds light on the dynamic magnetization process in iron/resin soft magnetic composites from the viewpoint of quantitative decomposition of their complex permeability spectra into the viscous domain wall motion and magnetization rotation. We present a comprehensive view on this phenomenon over the broad family of samples with different average particles dimension and dielectric matrix content. The results reveal the pure relaxation nature of magnetization processes without observation of spin resonance. The smaller particles and higher amount of insulating resin result in the prevalence of rotations over domain wall movement. The findings are elucidated in terms of demagnetizing effects rising from the heterogeneity of composite materials. - Highlights: • A first decomposition of complex permeability into domain wall and rotation parts in soft magnetic composites. • A pure relaxation nature of dynamic magnetization processes. • A complete loss separation in soft magnetic composites. • The domain walls activity is considerably suppressed in composites with smaller iron particles and higher matrix content. • The demagnetizing field acts as a significant factor at the dynamic magnetization process.
The advantage of high relaxivity contrast agents in brain perfusion

International Nuclear Information System (INIS)

Cotton, F.; Hermier, M.

2006-01-01

Accurate MRI characterization of brain lesions is critical for planning therapeutic strategy, assessing prognosis and monitoring response to therapy. Conventional MRI with gadolinium-based contrast agents is useful for the evaluation of brain lesions, but this approach primarily depicts areas of disruption of the blood-brain barrier (BBB) rather than tissue perfusion. Advanced MR imaging techniques such as dynamic contrast agent-enhanced perfusion MRI provide physiological information that complements the anatomic data available from conventional MRI. We evaluated brain perfusion imaging with gadobenate dimeglumine (Gd-BOPTA, MultiHance; Bracco Imaging, Milan, Italy). The contrast-enhanced perfusion technique was performed on a Philips Intera 1.5-T MR system. The technique used to obtain perfusion images was dynamic susceptibility contrast-enhanced MRI, which is highly sensitive to T2* changes. Combined with PRESTO perfusion imaging, SENSE is applied to double the temporal resolution, thereby improving the signal intensity curve fit and, accordingly, the accuracy of the derived parametric images. MultiHance is the first gadolinium MR contrast agent with significantly higher T1 and T2 relaxivities than conventional MR contrast agents. The higher T1 relaxivity, and therefore better contrast-enhanced T1-weighted imaging, leads to significantly improved detection of BBB breakdown and hence improved brain tumor conspicuity and delineation. The higher T2 relaxivity allows high-quality T2*-weighted perfusion MRI and the derivation of good quality relative cerebral blood volume (rCBV) maps. We determined the value of MultiHance for enhanced T2*-weighted perfusion imaging of histologically proven (by surgery or stereotaxic biopsy) intraaxial brain tumors (n=80), multiple sclerosis lesions (n=10), abscesses (n=4), neurolupus (n=15) and stroke (n=16). All the procedures carried out were safe and no adverse events occurred. The acquired perfusion images were of good quality in
Universal relaxation times for electron and nucleon gases

OpenAIRE

Pelc, M.; Marciak-Kozlowska, J.; Kozlowski, M.

2007-01-01

In this paper we calculate the universal relaxation times for electron and nucleon fermionic gases. We argue that the universal relaxation time tau(i) is equal tau(i)=h/m square v(i) where v(i)=alpha(i)c and alpha(1)=0.15 for nucleon gas and alpha(2)=1/137 for electron gas, c=light velocity. With the universal relaxation time we formulate the thermal Proca equation for fermionic gases. Key words: universal relaxation time, thermal universal Proca equation.
Anomalous relaxation and self-organization in nonequilibrium processes

International Nuclear Information System (INIS)

Fatkullin, Ibrahim; Kladko, Konstantin; Mitkov, Igor; Bishop, A. R.

2001-01-01

We study thermal relaxation in ordered arrays of coupled nonlinear elements with external driving. We find that our model exhibits dynamic self-organization manifested in a universal stretched-exponential form of relaxation. We identify two types of self-organization, cooperative and anticooperative, which lead to fast and slow relaxation, respectively. We give a qualitative explanation for the behavior of the stretched exponent in different parameter ranges. We emphasize that this is a system exhibiting stretched-exponential relaxation without explicit disorder or frustration
Spin relaxation of iron in mixed state hemoproteins

International Nuclear Information System (INIS)

Wajnberg, E.; Kalinowski, H.J.; Bemski, G.; Helman, J.S.

1984-01-01

In pure states hemoproteins the relaxation of iron depends on its spin state. It is found that in both mixed state met-hemoglobin and met-myoglobin, the low and high spin states relax through an Orbach-like process. Also, very short (approx. 1 ns) and temperature independent transverse relaxation times T 2 were estimated. This peculiar behaviour of the relaxation may result from the unusual electronic structure of mixed state hemoproteins that allows thermal equilibrium and interconversion of the spin states. (Author) [pt
Superparamagnetic relaxation of weakly interacting particles

DEFF Research Database (Denmark)

Mørup, Steen; Tronc, Elisabeth

1994-01-01

The influence of particle interactions on the superparamagnetic relaxation time has been studied by Mossbauer spectroscopy in samples of maghemite (gamma-Fe2O3) particles with different particle sizes and particle separations. It is found that the relaxation time decreases with decreasing particl...
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
Stress Relaxation in Entangled Polymer Melts

DEFF Research Database (Denmark)

Hou, Ji-Xuan; Svaneborg, Carsten; Everaers, Ralf

2010-01-01

We present an extensive set of simulation results for the stress relaxation in equilibrium and step-strained bead-spring polymer melts. The data allow us to explore the chain dynamics and the shear relaxation modulus, G(t), into the plateau regime for chains with Z=40 entanglements...... and into the terminal relaxation regime for Z=10. Using the known (Rouse) mobility of unentangled chains and the melt entanglement length determined via the primitive path analysis of the microscopic topological state of our systems, we have performed parameter-free tests of several different tube models. We find...
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
Improved memristor-based relaxation oscillator

KAUST Repository

Mosad, Ahmed G.

2013-09-01

This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is discussed and validated by the PSPICE circuit simulations showing an excellent agreement. MATLAB results are also introduced to demonstrate the resistance range and the corresponding frequency range which can be obtained from the proposed relaxation oscillator. © 2013 Elsevier Ltd.
Massive IIA string theory and Matrix theory compactification

International Nuclear Information System (INIS)

Lowe, David A.; Nastase, Horatiu; Ramgoolam, Sanjaye

2003-01-01

We propose a Matrix theory approach to Romans' massive Type IIA supergravity. It is obtained by applying the procedure of Matrix theory compactifications to Hull's proposal of the massive Type IIA string theory as M-theory on a twisted torus. The resulting Matrix theory is a super-Yang-Mills theory on large N three-branes with a space-dependent noncommutativity parameter, which is also independently derived by a T-duality approach. We give evidence showing that the energies of a class of physical excitations of the super-Yang-Mills theory show the correct symmetry expected from massive Type IIA string theory in a lightcone quantization
Parameterization of NMR relaxation curves in terms of logarithmic moments of the relaxation time distribution.

Science.gov (United States)

Petrov, Oleg V; Stapf, Siegfried

2017-06-01

This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution. Copyright © 2017 Elsevier Inc. All rights reserved.
Parameterization of NMR relaxation curves in terms of logarithmic moments of the relaxation time distribution

Science.gov (United States)

Petrov, Oleg V.; Stapf, Siegfried

2017-06-01

This work addresses the problem of a compact and easily comparable representation of multi-exponential relaxation data. It is often convenient to describe such data in a few parameters, all being of physical significance and easy to interpret, and in such a way that enables a model-free comparison between different groups of samples. Logarithmic moments (LMs) of the relaxation time constitute a set of parameters which are related to the characteristic relaxation time on the log-scale, the width and the asymmetry of an underlying distribution of exponentials. On the other hand, the calculation of LMs does not require knowing the actual distribution function and is reduced to a numerical integration of original data. The performance of this method has been tested on both synthetic and experimental NMR relaxation data which differ in a signal-to-noise ratio, the sampling range and the sampling rate. The calculation of two lower-order LMs, the log-mean time and the log-variance, has proved robust against deficiencies of the experiment such as scattered data point and incomplete sampling. One may consider using them as such to monitor formation of a heterogeneous structure, e.g., in phase separation, vitrification, polymerization, hydration, aging, contrast agent propagation processes. It may also assist in interpreting frequency and temperature dependences of relaxation, revealing a crossover from slow to fast exchange between populations. The third LM was found to be a less reliable quantity due to its susceptibility to the noise and must be used with caution.
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
Simulation study of stepwise relaxation in a spheromak plasma

International Nuclear Information System (INIS)

Horiuchi, Ritoku; Uchida, Masaya; Sato, Tetsuya.

1991-10-01

The energy relaxation process of a spheromak plasma in a flux conserver is investigated by means of a three-dimensional magnetohydrodynamic simulation. The resistive decay of an initial force-free profile brings the spheromak plasma to an m = 1/n = 2 ideal kink unstable region. It is found that the energy relaxation takes place in two steps; namely, the relaxation consists of two physically distinguished phases, and there exists an intermediate phase in between, during which the relaxation becomes inactive temporarily. The first relaxation corresponds to the transition from an axially symmetric force-free state to a helically symmetric one with an n = 2 crescent magnetic island structure via the helical kink instability. The n = 2 helical structure is nonlinearly sustained in the intermediate phase. The helical twisting of the flux tube creates a reconnection current in the vicinity of the geometrical axis. The second relaxation is triggered by the rapid growth of the n = 1 mode when the reconnection current exceeds a critical value. The helical twisting relaxes through magnetic reconnection toward an axially symmetric force-free state. It is also found that the poloidal flux reduces during the helical twisting in the first relaxation and the generation of the toroidal flux occurs through the magnetic reconnection process in the second relaxation. (author)
Superparamagnetic relaxation in alpha-Fe particles

DEFF Research Database (Denmark)

Bødker, Franz; Mørup, Steen; Pedersen, Michael Stanley

1998-01-01

The superparamagnetic relaxation time of carbon-supported alpha-Fe particles with an average size of 3.0 Mm has been studied over a large temperature range by the use of Mossbauer spectroscopy combined with AC and DC magnetization measurements. It is found that the relaxation time varies...
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…
Tensor operators in R-matrix approach

International Nuclear Information System (INIS)

Bytsko, A.G.; Rossijskaya Akademiya Nauk, St. Petersburg

1995-12-01

The definitions and some properties (e.g. the Wigner-Eckart theorem, the fusion procedure) of covariant and contravariant q-tensor operators for quasitriangular quantum Lie algebras are formulated in the R-matrix language. The case of U q (sl(n)) (in particular, for n=2) is discussed in more detail. (orig.)
Magnetic relaxation in analytical, coordination and bioinorganic chemistry

International Nuclear Information System (INIS)

Mikhajlov, O.

1982-01-01

Nuclear magnetic relaxation is a special type of nuclear magnetic resonance in which the rate is measured of energy transfer between the excited nuclei and their molecular medium (spin-lattice relaxation) or the whole nuclear spin system (spin-spin relaxation). Nuclear magnetic relaxation relates to nuclei with a spin of 1/2, primarily H 1 1 , and is mainly measured in water solutions. It is suitable for (1) analytical chemistry because the relaxation time rapidly reduces in the presence of paramagnetic ions, (2) the study of complex compounds, (3) the study of biochemical reactions in the presence of different metal ions. It is also suitable for testing the composition of a flowing liquid. Its disadvantage is that it requires complex and expensive equipment. (Ha)

Structural relaxation in annealed hyperquenched basaltic glasses

DEFF Research Database (Denmark)

Guo, Xiaoju; Mauro, John C.; Potuzak, M.

2012-01-01

The enthalpy relaxation behavior of hyperquenched (HQ) and annealed hyperquenched (AHQ) basaltic glass is investigated through calorimetric measurements. The results reveal a common onset temperature of the glass transition for all the HQ and AHQ glasses under study, indicating that the primary...... relaxation is activated at the same temperature regardless of the initial departure from equilibrium. The analysis of secondary relaxation at different annealing temperatures provides insights into the enthalpy recovery of HQ glasses....
Metal matrix composites synthesis, wear characteristics, machinability study of MMC brake drum

CERN Document Server

Natarajan, Nanjappan; Davim, J Paulo

2015-01-01

This book is dedicated to composite materials, presenting different synthesis processes, composite properties and their machining behaviour. The book describes also the problems on manufacturing of metal matrix composite components. Among others, it provides procedures for manufacturing of metal matrix composites and case studies.
Relaxed states of tokamak plasmas

International Nuclear Information System (INIS)

Kucinski, M.Y.; Okano, V.

1993-01-01

The relaxed states of tokamak plasmas are studied. It is assumed that the plasma relaxes to a quasi-steady state which is characterized by a minimum entropy production rate, compatible with a number of prescribed conditions and pressure balance. A poloidal current arises naturally due to the anisotropic resistivity. The minimum entropy production theory is applied, assuming the pressure equilibrium as fundamental constraint on the final state. (L.C.J.A.)
Negative magnetic relaxation in superconductors

Directory of Open Access Journals (Sweden)

Krasnoperov E.P.

2013-01-01

Full Text Available It was observed that the trapped magnetic moment of HTS tablets or annuli increases in time (negative relaxation if they are not completely magnetized by a pulsed magnetic field. It is shown, in the framework of the Bean critical-state model, that the radial temperature gradient appearing in tablets or annuli during a pulsed field magnetization can explain the negative magnetic relaxation in the superconductor.
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
Magnetic relaxation induced by transverse flux shaking in MgB{sub 2} superconductors

Energy Technology Data Exchange (ETDEWEB)

Luzuriaga, J; Nieva, G; Serquis, A; Serrano, G [Centro Atomico Bariloche, CNEA, Instituto Balseiro, UNC (Argentina); BadIa-Majos, A [Departamento de Fisica de la Materia Condensada-ICMA, Universidad de Zaragoza-CSIC (Spain); Giordano, J L [Departamento de Ciencias de la IngenierIa, Universidad de Talca (Chile); Lopez, C [Departamento de Matematicas, Universidad de Alcala de Henares (Spain)], E-mail: luzuriag@cab.cnea.gov.ar

2009-01-15

We report on measurements and numerical simulations of the behavior of MgB{sub 2} superconductors when magnetic field components are applied along mutually perpendicular directions. By closely matching the geometry in simulations and measurements, full quantitative agreement is found. The critical state theory and a single phenomenological law, i.e. the field dependence of the critical current density J{sub c}(B), are sufficient for a full quantitative description of the measurements. These were performed in thick strips of carbon nanotube doped MgB{sub 2} samples. Magnetization was measured in two orthogonal directions using a SQUID magnetometer. Magnetic relaxation effects induced by the application of an oscillatory perpendicular field were observed and simulated numerically. The measurements confirm the numerical predictions, that two relaxation regimes appear, depending on the amplitude of the applied magnetic field. The overall agreement constitutes a convincing validation of the critical state model and the numerical procedures used.
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
Structural relaxation and thermal conductivity coefficient of liquids

International Nuclear Information System (INIS)

Abdurasulov, A.

1992-01-01

Present article is devoted to structural relaxation and thermal conductivity coefficient of liquids. The thermoelastic properties of liquids were studied taking into account the contribution of translational and structural relaxation. The results of determination of dynamic coefficient of thermal conductivity of liquids taking into account the contribution of translational and structural relaxation are presented.
A collocation finite element method with prior matrix condensation

International Nuclear Information System (INIS)

Sutcliffe, W.J.

1977-01-01

For thin shells with general loading, sixteen degrees of freedom have been used for a previous finite element solution procedure using a Collocation method instead of the usual variational based procedures. Although the number of elements required was relatively small, nevertheless the final matrix for the simultaneous solution of all unknowns could become large for a complex compound structure. The purpose of the present paper is to demonstrate a method of reducing the final matrix size, so allowing solution for large structures with comparatively small computer storage requirements while retaining the accuracy given by high order displacement functions. Collocation points, a number are equilibrium conditions which must be satisfied independently of the overall compatibility of forces and deflections for a complete structure. (Auth.)
Efficiency criterion for teleportation via channel matrix, measurement matrix and collapsed matrix

Directory of Open Access Journals (Sweden)

Xin-Wei Zha

Full Text Available In this paper, three kinds of coefficient matrixes (channel matrix, measurement matrix, collapsed matrix associated with the pure state for teleportation are presented, the general relation among channel matrix, measurement matrix and collapsed matrix is obtained. In addition, a criterion for judging whether a state can be teleported successfully is given, depending on the relation between the number of parameter of an unknown state and the rank of the collapsed matrix. Keywords: Channel matrix, Measurement matrix, Collapsed matrix, Teleportation
Relaxation of a coherent, magnetic s–p model system coupled to one and two thermal baths and a laser pulse

Energy Technology Data Exchange (ETDEWEB)

Lefkidis, G. [Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Box 3049, 67653 Kaiserslautern (Germany); School of Mechanics, Civil Engineering and Architecture, Northwestern Polytechnical University, Xi’an 710072 (China); Sold, S.; Hübner, W. [Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Box 3049, 67653 Kaiserslautern (Germany)

2017-06-15

We study an s–p model magnetic system with a triplet ground state coupled to two temperature baths. By varying the temperatures we both generate non-thermal electronic distributions and create additional coherences in the density matrix of the system. Thus the thermally-induced magnetic response goes beyond the simple picture of majority-minority population dynamics. Furthermore, we discuss the influence of temperature induced relaxation effects on the dynamics induced by an optical perturbation for this quantum system.
Nuclear spin-lattice relaxation in nitroxide spin-label EPR

DEFF Research Database (Denmark)

Marsh, Derek

2016-01-01

that the definition of nitrogen nuclear relaxation rate Wn commonly used in the CW-EPR literature for 14N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14N spin-lattice relaxation rate, b = Wn/(2We), preserves...... of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14N-relaxation: T1 n = 1/Wn. Results are compared and contrasted...
A Globally Convergent Matrix-Free Method for Constrained Equations and Its Linear Convergence Rate

Directory of Open Access Journals (Sweden)

Min Sun

2014-01-01

Full Text Available A matrix-free method for constrained equations is proposed, which is a combination of the well-known PRP (Polak-Ribière-Polyak conjugate gradient method and the famous hyperplane projection method. The new method is not only derivative-free, but also completely matrix-free, and consequently, it can be applied to solve large-scale constrained equations. We obtain global convergence of the new method without any differentiability requirement on the constrained equations. Compared with the existing gradient methods for solving such problem, the new method possesses linear convergence rate under standard conditions, and a relax factor γ is attached in the update step to accelerate convergence. Preliminary numerical results show that it is promising in practice.
Picosecond absorption relaxation measured with nanosecond laser photoacoustics.

Science.gov (United States)

Danielli, Amos; Favazza, Christopher P; Maslov, Konstantin; Wang, Lihong V

2010-10-18

Picosecond absorption relaxation-central to many disciplines-is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, both possessing extremely low fluorescence quantum yields, were measured at 576 nm. The added advantages in dispersion susceptibility, laser-wavelength availability, reflection sensing, and expense foster the study of natural-including strongly scattering and nonfluorescent-materials.
Dielectric relaxations and conduction mechanisms in polyether-clay composite polymer electrolytes under high carbon dioxide pressure.

Science.gov (United States)

Kitajima, Shunsuke; Bertasi, Federico; Vezzù, Keti; Negro, Enrico; Tominaga, Yoichi; Di Noto, Vito

2013-10-21

The composite material P(EO/EM)-Sa consisting of synthetic saponite (Sa) dispersed in poly[ethylene oxide-co-2-(2-methoxyethoxy)ethyl glycidyl ether] (P(EO/EM)) is studied by "in situ" measurements using broadband electrical spectroscopy (BES) under pressurized CO2 to characterize the dynamic behavior of conductivity and the dielectric relaxations of the ion host polymer matrix. It is revealed that there are three dielectric relaxation processes associated with: (I) the dipolar motions in the short oxyethylene side chains of P(EO/EM) (β); and (II) the segmental motion of the main chains comprising the polyether components (αfast, αslow). αslow is attributed to the slow α-relaxation of P(EO/EM) macromolecules, which is hindered by the strong coordination interactions with the ions. Two conduction processes are observed, σDC and σID, which are attributed, respectively, to the bulk conductivity and the interdomain conductivity. The temperature dependence of conductivity and relaxation processes reveals that αfast and αslow are strongly correlated with σDC and σID. The "in situ" BES measurements under pressurized CO2 indicate a fast decrease in σDC at the initial CO2 treatment time resulting from the decrease in the concentration of polyether-M(n+) complexes, which is driven by the CO2 permeation. The relaxation frequency (fR) of αslow at the initial CO2 treatment time increases and shows a steep rise with time with the same behavior of the αfast mode. It is demonstrated that the interactions between polyether chains of P(EO/EM) and cations in the polymer electrolyte layers embedded in Sa are probably weakened by the low permittivity of CO2 (ε = 1.08). Thus, the formation of ion pairs in the polymer electrolyte domains of P(EO/EM)-Sa occurs, with a corresponding reduction in the concentration of ion carriers.
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
Stress relaxation and hillock growth in thin films

International Nuclear Information System (INIS)

Jackson, M.S.; Li, C.Y.

1978-01-01

The relaxation of thermal stress in a thin film adhering to a substrate of differing expansion coefficient is discussed. Good agreement is found between literature data on relaxation during isothermal anneals of Pb films at up to 350 0 K and model calculations based on a state variable description of plastic flow. The stress system during relaxation is explored, and the absence of diffusional creep is explained. The plasticity-dominated relaxation process suggested by this analysis is shown to be in good qualitative agreement with data on rapid relaxation over the course of a cycle between room and cryogenic temperatures. The implications of this for long-range material transport in the film are discussed. It is shown that hillock volume should increase over the course of a temperature cycle. Finally, a mechanism for hillock nucleation based on grain boundary sliding is suggested
General factorization relations and consistency conditions in the sudden approximation via infinite matrix inversion

International Nuclear Information System (INIS)

Chan, C.K.; Hoffman, D.K.; Evans, J.W.

1985-01-01

Local, i.e., multiplicative, operators satisfy well-known linear factorization relations wherein matrix elements (between states associated with a complete set of wave functions) can be obtained as a linear combination of those out of the ground state (the input data). Analytic derivation of factorization relations for general state input data results in singular integral expressions for the coefficients, which can, however, be regularized using consistency conditions between matrix elements out of a single (nonground) state. Similar results hold for suitable ''symmetry class'' averaged matrix elements where the symmetry class projection operators are ''complete.'' In several cases where the wave functions or projection operators incorporate orthogonal polynomial dependence, we show that the ground state factorization relations have a simplified structure allowing an alternative derivation of the general factorization relations via an infinite matrix inversion procedure. This form is shown to have some advantages over previous versions. In addition, this matrix inversion procedure obtains all consistency conditions (which is not always the case from regularization of singular integrals)
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.
Relaxation as a Factor in Semantic Desensitization

Science.gov (United States)

Bechtel, James E.; McNamara, J. Regis

1975-01-01

Relaxation and semantic desensitization were used to alleviate the fear of phobic females. Results showed that semantic desensitization, alone or in combination with relaxation, failed to modify the evaluative meanings evoked by the feared object. (SE)

Nuclear spin-lattice relaxation in nitroxide spin-label EPR.

Science.gov (United States)

Marsh, Derek

2016-11-01

Nuclear relaxation is a sensitive monitor of rotational dynamics in spin-label EPR. It also contributes competing saturation transfer pathways in T 1 -exchange spectroscopy, and the determination of paramagnetic relaxation enhancement in site-directed spin labelling. A survey shows that the definition of nitrogen nuclear relaxation rate W n commonly used in the CW-EPR literature for 14 N-nitroxyl spin labels is inconsistent with that currently adopted in time-resolved EPR measurements of saturation recovery. Redefinition of the normalised 14 N spin-lattice relaxation rate, b=W n /(2W e ), preserves the expressions used for CW-EPR, whilst rendering them consistent with expressions for saturation recovery rates in pulsed EPR. Furthermore, values routinely quoted for nuclear relaxation times that are deduced from EPR spectral diffusion rates in 14 N-nitroxyl spin labels do not accord with conventional analysis of spin-lattice relaxation in this three-level system. Expressions for CW-saturation EPR with the revised definitions are summarised. Data on nitrogen nuclear spin-lattice relaxation times are compiled according to the three-level scheme for 14 N-relaxation: T 1 n =1/W n . Results are compared and contrasted with those for the two-level 15 N-nitroxide system. Copyright © 2016 Elsevier Inc. All rights reserved.
Nuclear magnetic resonance relaxation in multiple sclerosis

DEFF Research Database (Denmark)

Larsson, H B; Barker, G J; MacKay, A

1998-01-01

OBJECTIVES: The theory of relaxation processes and their measurements are described. An overview is presented of the literature on relaxation time measurements in the normal and the developing brain, in experimental diseases in animals, and in patients with multiple sclerosis. RESULTS...... AND CONCLUSION: Relaxation time measurements provide insight into development of multiple sclerosis plaques, especially the occurrence of oedema, demyelination, and gliosis. There is also evidence that normal appearing white matter in patients with multiple sclerosis is affected. What is now needed are fast...
Biological conduits combining bone marrow mesenchymal stem cells and extracellular matrix to treat long-segment sciatic nerve defects

Directory of Open Access Journals (Sweden)

Yang Wang

2015-01-01

Full Text Available The transplantation of polylactic glycolic acid conduits combining bone marrow mesenchymal stem cells and extracellular matrix gel for the repair of sciatic nerve injury is effective in some respects, but few data comparing the biomechanical factors related to the sciatic nerve are available. In the present study, rabbit models of 10-mm sciatic nerve defects were prepared. The rabbit models were repaired with autologous nerve, a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells, or a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel. After 24 weeks, mechanical testing was performed to determine the stress relaxation and creep parameters. Following sciatic nerve injury, the magnitudes of the stress decrease and strain increase at 7,200 seconds were largest in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group, followed by the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group, and then the autologous nerve group. Hematoxylin-eosin staining demonstrated that compared with the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells group and the autologous nerve group, a more complete sciatic nerve regeneration was found, including good myelination, regularly arranged nerve fibers, and a completely degraded and resorbed conduit, in the polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel group. These results indicate that bridging 10-mm sciatic nerve defects with a polylactic glycolic acid conduit + bone marrow mesenchymal stem cells + extracellular matrix gel construct increases the stress relaxation under a constant strain, reducing anastomotic tension. Large elongations under a constant physiological load can limit the anastomotic opening and shift, which is beneficial for the regeneration and functional reconstruction of sciatic nerve. Better
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.
The use of (double) relaxation oscillation SQUIDs as a sensor

NARCIS (Netherlands)

van Duuren, M.J.; Brons, G.C.S.; Kattouw, H.; Flokstra, Jakob; Rogalla, Horst

1997-01-01

Relaxation Oscillation SQUIDs (ROSs) and Double Relaxation Oscillation SQUIDs (DROSs) are based on relaxation oscillations that are induced in hysteretic dc SQUIDs by an external L-R shunt. The relaxation frequency of a ROS varies with the applied flux Φ, whereas the output of a DROS is a dc
Relaxation strain measurements in cellular dislocation structures

International Nuclear Information System (INIS)

Tsai, C.Y.; Quesnel, D.J.

1984-01-01

The conventional picture of what happens during a stress relaxation usually involves imagining the response of a single dislocation to a steadily decreasing stress. The velocity of this dislocation decreases with decreasing stress in such a way that we can measure the stress dependence of the dislocation velocity. Analysis of the data from a different viewpoint enables us to calculate the apparent activation volume for the motion of the dislocation under the assumption of thermally activated glie. Conventional thinking about stress relaxation, however, does not consider the eventual fate of this dislocation. If the stress relaxes to a low enough level, it is clear that the dislocation must stop. This is consistent with the idea that we can determine the stress dependence of the dislocation velocity from relaxation data only for those cases where the dislocation's velocity is allowed to approach zero asymptotically, in short, for those cases where the dislocation never stops. This conflict poses a dilemma for the experimentalist. In real crystals, however, obstacles impede the dislocation's progress so that those dislocations which are stopped at a given stress will probably never resume motion under the influence of the steadily declining stress present during relaxation. Thus one could envision stress relaxation as a process of exhaustion of mobile dislocations, rather than a process of decreasing dislocation velocity. Clearly both points of view have merit and in reality both mechanisms contribute to the phenomena
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.
F19 relaxation in non-magnetic hexafluorides

International Nuclear Information System (INIS)

Rigny, P.

1969-01-01

The interesting properties of the fluorine magnetic resonance in the hexafluorides of molybdenum, tungsten and uranium, are very much due to large anisotropies of the chemical shift tensors. In the solid phases these anisotropies, the values of which are deduced from line shape studies, allow one to show that the molecules undergo hindered rotations about the metal atom. The temperature and frequency dependence of the fluorine longitudinal relaxation times shows that the relaxation is due to the molecular motion. The dynamical parameters of this motion are then deduced from the complete study of the fluorine relaxation in the rotating frame. In the liquid phases, the existence of anisotropies allows an estimation of the different contributions to the relaxation. In particular, the frequency and temperature dependence of the relaxation shows it to be dominated by the spin-rotation interaction. We have shown that the strength of this interaction can be deduced from the chemical shifts, and the angle through which the molecule rotates quasi-freely can be determined. In the hexafluorides, this angle is roughly one radian at 70 C, and with the help of this value, the friction coefficients which describe the intermolecular interactions are discussed. (author) [fr
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...
Relaxation-phenomena in LiAl/FeS-cells

Science.gov (United States)

Borger, W.; Kappus, W.; Panesar, H. S.

A theoretical model of the capacity of strongly relaxing electrochemical systems is applied to the LiAl/FeS system. Relaxation phenomena in LiAl and FeS electrodes can be described by this model. Experimental relaxation data indicate that lithium transport through the alpha-LiAl layer to the particle surface is the capacity limiting process at high discharge current density in the LiAl electrode in LiCl-KCl and LiF-LiCl-LiBr mixtures. Strong relaxation is observed in the FeS electrode with LiCl-KCl electrolyte caused by lithium concentration gradients and precipitation of KCl in the pores.
Relaxation of polarized nuclei in superconducting rhodium

DEFF Research Database (Denmark)

Knuuttila, T.A.; Tuoriniemi, J.T.; Lefmann, K.

2000-01-01

Nuclear spin lattice relaxation rates were measured in normal and superconducting (sc) rhodium with nuclear polarizations up to p = 0.55. This was sufficient to influence the sc state of Rh, whose T, and B-c, are exceptionally low. Because B-c ... is unchanged, the nuclear spin entropy was fully sustained across the sc transition. The relaxation in the sc state was slower at all temperatures without the coherence enhancement close to T-c. Nonzero nuclear polarization strongly reduced the difference between the relaxation rates in the sc and normal...
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.)
Structural differences of matrix metalloproteinases. Homology modeling and energy minimization of enzyme-substrate complexes

DEFF Research Database (Denmark)

Terp, G E; Christensen, I T; Jørgensen, Flemming Steen

2000-01-01

Matrix metalloproteinases are extracellular enzymes taking part in the remodeling of extracellular matrix. The structures of the catalytic domain of MMP1, MMP3, MMP7 and MMP8 are known, but structures of enzymes belonging to this family still remain to be determined. A general approach...... to the homology modeling of matrix metalloproteinases, exemplified by the modeling of MMP2, MMP9, MMP12 and MMP14 is described. The models were refined using an energy minimization procedure developed for matrix metalloproteinases. This procedure includes incorporation of parameters for zinc and calcium ions...... in the AMBER 4.1 force field, applying a non-bonded approach and a full ion charge representation. Energy minimization of the apoenzymes yielded structures with distorted active sites, while reliable three-dimensional structures of the enzymes containing a substrate in active site were obtained. The structural...
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.
Picosecond absorption relaxation measured with nanosecond laser photoacoustics

OpenAIRE

Danielli, Amos; Favazza, Christopher P.; Maslov, Konstantin; Wang, Lihong V.

2010-01-01

Picosecond absorption relaxation—central to many disciplines—is typically measured by ultrafast (femtosecond or picosecond) pump-probe techniques, which however are restricted to optically thin and weakly scattering materials or require artificial sample preparation. Here, we developed a reflection-mode relaxation photoacoustic microscope based on a nanosecond laser and measured picosecond absorption relaxation times. The relaxation times of oxygenated and deoxygenated hemoglobin molecules, b...
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.
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.
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
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
Baryogenesis via Elementary Goldstone Higgs Relaxation

DEFF Research Database (Denmark)

Gertov, Helene; Pearce, Lauren; Sannino, Francesco

2016-01-01

We extend the relaxation mechanism to the Elementary Goldstone Higgs framework. Besides studying the allowed parameter space of the theory we add the minimal ingredients needed for the framework to be phenomenologically viable. The very nature of the extended Higgs sector allows to consider very ...... but radiatively generated, it is possible to generate the observed matter-antimatter asymmetry via the relaxation mechanism....
[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.
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
Relaxations in spin glasses: Similarities and differences from ordinary glasses

International Nuclear Information System (INIS)

Ngai, K.L.; Rajagopal, A.K.; Huang, C.Y.

1984-01-01

Relaxation phenomena have become a major concern in the physics of spin glasses. There are certain resemblances of these relaxation properties to those of ordinary glasses. In this work, we compare the relaxation properties of spin glasses near the freezing temperature with those of glasses near the glass transition temperature. There are similarities between the two types of glasses. Moreover, the relaxation properties of many glasses and spin glasses are in conformity with two coupled ''universality'' relations predicted by a recent model of relaxations in condensed matter
The effects of progressive muscular relaxation as a nursing procedure used for those who suffer from stress due to multiple sclerosis.

Science.gov (United States)

Novais, Paolla Gabrielle Nascimento; Batista, Karla de Melo; Grazziano, Eliane da Silva; Amorim, Maria Helena Costa

2016-09-01

to evaluate the effect of progressive muscle relaxation as a nursing procedure on the levels of stress for sufferers of multiple sclerosis. random clinical trials conducted at the Neurology outpatients unit at a University Hospital. The sample consisted of 40 patients who were being monitored as outpatients (20 in a control group and 20 in an experimental group). The Progressive Muscle Relaxation technique was used. The control variables were collected through interviews that were recorded on forms and on the Perceived Stress Scale that we used. Five meetings were held every fortnight covering a period of eight weeks. The experimental group was advised to carry out daily progressive muscle relaxation activities. After eight weeks of these activities, they were evaluated again to measure their levels of stress. In order to analyze the data used, the software package Statistics for Social Sciences version 19.0 was used. the application of the t test showed a significant reduction in the Perceived Stress Scale scores in the experimental group (pencontros quinzenais em um período de oito semanas. O grupo experimental foi orientado a realizar diariamente o Relaxamento Muscular Progressivo. Após oito semanas de intervenção avaliou-se novamente os níveis de estresse. Para análise dos dados foi utilizado o pacote Estatístico para Ciências Sociais-versão 19.0. a aplicação do Teste t demonstrou uma diminuição significante dos escores da Escala de Stress Percebido no grupo experimental (p<0,001), evidenciando diminuição nos níveis de estresse após a prática do relaxamento. a intervenção Relaxamento Muscular Progressivo contribui para redução dos níveis de estresse em pessoas com Esclerose Múltipla, podendo ser incluída como prática na assistência de enfermagem prestada a esses pacientes. NCT 02673827. evaluar el efecto del Relajamiento Muscular Progresivo, como intervención de Enfermería en los niveles de estrés en personas con Esclerosis
STAR FORMATION AND RELAXATION IN 379 NEARBY GALAXY CLUSTERS

International Nuclear Information System (INIS)

Cohen, Seth A.; Hickox, Ryan C.; Wegner, Gary A.

2015-01-01

We investigate the relationship between star formation (SF) and level of relaxation in a sample of 379 galaxy clusters at z < 0.2. We use data from the Sloan Digital Sky Survey to measure cluster membership and level of relaxation, and to select star-forming galaxies based on mid-infrared emission detected with the Wide-Field Infrared Survey Explorer. For galaxies with absolute magnitudes M r < −19.5, we find an inverse correlation between SF fraction and cluster relaxation: as a cluster becomes less relaxed, its SF fraction increases. Furthermore, in general, the subtracted SF fraction in all unrelaxed clusters (0.117 ± 0.003) is higher than that in all relaxed clusters (0.097 ± 0.005). We verify the validity of our SF calculation methods and membership criteria through analysis of previous work. Our results agree with previous findings that a weak correlation exists between cluster SF and dynamical state, possibly because unrelaxed clusters are less evolved relative to relaxed clusters
The relaxation of plasmas with dust particles

International Nuclear Information System (INIS)

Chutov, Yu.I.; Kravchenko, A.Yu.; Schram, P.P.J.M.

1997-01-01

Various parameters of relaxing plasmas with dust particles including the electron and ion energy distributions function are numerically simulated at various parameters of the dust particles using the PIC method and taking into account the dynamics of the dust particle charge without the assumption about the equilibrium of electrons and ions. Coulomb collisions are taken into account in the framework of the method of stochastic differential equations. The relaxation of bounded plasma clouds expanding into a vacuum as well as the relaxation of a uniform plasma, in which dust particles appear at some initial time, are investigated. The obtained results show that the relaxation of plasmas can be accompanied by a deviation of the ion distribution function from equilibrium as well as a change of the mean energy of electrons and ions because of the dependence of the collection of electrons and ions by dust particles on their energy. (author)
The modified relaxation time function: A novel analysis technique for relaxation processes. Application to high-temperature molybdenum internal friction peaks

International Nuclear Information System (INIS)

Matteo, C.L.; Lambri, O.A.; Zelada-Lambri, G.I.; Sorichetti, P.A.; Garcia, J.A.

2008-01-01

The modified relaxation time (MRT) function, which is based on a general linear viscoelastic formalism, has several important mathematical properties that greatly simplify the analysis of relaxation processes. In this work, the MRT is applied to the study of the relaxation damping peaks in deformed molybdenum at high temperatures. The dependence of experimental data from these relaxation processes with temperature are adequately described by a Havriliak-Negami (HN) function, and the MRT makes it possible to find a relation between the parameters of the HN function and the activation energy of the process. The analysis reveals that for the relaxation peak appearing at temperatures below 900 K, the physical mechanism is related to a vacancy-diffusion-controlled movement of dislocations. In contrast, when the peak appears at temperatures higher than 900 K, the damping is controlled by a mechanism of diffusion in the low-temperature tail of the peak, and in the high-temperature tail of the peak the creation plus diffusion of vacancies at the dislocation line occurs
Relationship between Structural and Stress Relaxation in a Block-Copolymer Melt

International Nuclear Information System (INIS)

Patel, Amish J.; Narayanan, Suresh; Sandy, Alec; Mochrie, Simon G. J.; Garetz, Bruce A.; Watanabe, Hiroshi; Balsara, Nitash P.

2006-01-01

The relationship between structural relaxation on molecular length scales and macroscopic stress relaxation was explored in a disordered block-copolymer melt. Experiments show that the structural relaxation time, measured by x-ray photon correlation spectroscopy is larger than the terminal stress relaxation time, measured by rheology, by factors as large as 100. We demonstrate that the structural relaxation data are dominated by the diffusion of intact micelles while the stress relaxation data are dominated by contributions due to disordered concentration fluctuations
Dielectric relaxation studies of dilute solutions of amides

Energy Technology Data Exchange (ETDEWEB)

Malathi, M.; Sabesan, R.; Krishnan, S

2003-11-15

The dielectric constants and dielectric losses of formamide, acetamide, N-methyl acetamide, acetanilide and N,N-dimethyl acetamide in dilute solutions of 1,4-dioxan/benzene have been measured at 308 K using 9.37 GHz, dielectric relaxation set up. The relaxation time for the over all rotation {tau}{sub (1)} and that for the group rotation {tau}{sub (2)} of (the molecules were determined using Higasi's method. The activation energies for the processes of dielectric relaxation and viscous flow were determined by using Eyring's rate theory. From relaxation time behaviour of amides in non-polar solvent, solute-solvent and solute-solute type of molecular association is proposed.
Relaxation of coupled nuclear spin systems

International Nuclear Information System (INIS)

Koenigsberger, E.

1985-05-01

The subject of the present work is the relaxation behaviour of scalarly coupled spin-1/2 systems. In the theoretical part the semiclassical Redfield equations are used. Dipolar (D), Chemical Shift Anisotropy (CSA) and Random Field (RF) interactions are considered as relaxation mechanisms. Cross correlations of dipolar interactions of different nuclei pairs and those between the D and the CSA mechanisms are important. The model of anisotropic molecular rotational relaxation and the extreme narrowing approximation are used to obtain the spectral density functions. The longitudinal relaxation data are analyzed into normal modes following Werbelow and Grant. The time evolution of normal modes is derived for the AX system with D-CSA cross terms. In the experimental part the hypothesis of dimerization in the cinnamic acid and the methyl cinnamate - AMX systems with DD cross terms - is corroborated by T 1 -time measurements and a calculation of the diffusion constants. In pentachlorobenzene - an AX system - taking into account of D-CSA cross terms enables the complete determination of movements anosotropy and the determination of the sign of the indirect coupling constant 1 Jsub(CH). (G.Q.)
General 4–zero texture mass matrix parametrizations

International Nuclear Information System (INIS)

Barranco, J; Delepine, D; Lopez-Lozano, L

2014-01-01

It is performed the diagonalization of a non–Hermitian four–zero texture Yukawa matrix with a general formalism. This procedure leads to 3 possibilities to parametrize the relation between the fermion masses and the elements of the corresponding Yukawa matrix. Then, the matrices that diagonalize each Yukawa mass matrix are combined in order to obtain 9 different theoretical CKM or PMNS mixing matrices [1]. Through a χ 2 analysis, we have constrained the values of the remaining free parameters such as the theoretical mixing matrix matches the latest experimental measurements of the mixing matrices. This analysis was done without assuming any approximations. In the case of the quark sector, it is found that only four different theoretical mixing matrices are compatible with the actual high precision experimental measurement of the CKM matrix elements. For the lepton sector, where the masses of neutrinos are not known, we found that independently of the parametrization that have been chosen, the updated experimental measurements of the mixing angles in the PMNS matrix, imply a mass for the heaviest left–handed neutrino to be ∼ 0.05eV
Experiments in paramagnetic relaxation

International Nuclear Information System (INIS)

Lijphart, E.E.

1976-01-01

This thesis presents two attempts to improve the resolving power of the relaxation measurement technique. The first attempt reconsiders the old technique of steady state saturation. When used in conjunction with the pulse technique, it offers the possibility of obtaining additional information about the system in which all-time derivatives are zero; in addition, non-linear effects may be distinguished from each other. The second attempt involved a systematic study of only one system: Cu in the Tutton salts (K and Rb). The systematic approach, the high accuracy of the measurement and the sheer amount of experimental data for varying temperature, magnetic field and concentration made it possible in this case to separate the prevailing relaxation mechanisms reliably
Fabrication and characterization of novel polymer-matrix nanocomposites and their constituents

Science.gov (United States)

Ding, Rui

Two main issues for the wide application of polymer-matrix nanocomposites need to be addressed: cost-effective processing of high-performance nanomaterials, and fundamental understanding of the nanofiller-polymer interaction related to property changes of nanocomposites. To fabricate inexpensive and robust carbon nanofibers (CNFs) by the electrospinning technique, an organosolv lignin for replacing polyacrylonitrile (PAN) precursor was investigated in this work. Modification of lignin to its butyl ester alters the electrospinnability and the thermal mobility of the lignin/PAN blend precursor fibers, which further affect the thermostabilization and carbonization processes of CNFs. The micromorphology, carbon structure, and mechanical properties of resultant CNFs were evaluated in detail. Lignin butyration reveals a new approach to controlling inter-fiber bonding of CNFs which efficiently increases the tensile strength and modulus of nonwoven mats. A commercial vapor-grown CNF reinforcing of room-temperature-vulcanized (RTV) polysiloxane foam has potential impact on the residual tin catalyst in composites and consequently the aging and the long-term performance of the materials. Elemental spectra and mapping were employed to analyze the distribution and the composition of tin catalyst residues in the CNF/polysiloxane composites. Thermal analysis revealed a significant increase of thermal stability for CNF-filled composites. Further, the glass transition properties of polysiloxane are not evidently influenced by the physical interaction between CNF filler and polysiloxane matrix. Nanocomposites consisting of anthracene, a model polycyclic aromatic hydrocarbon (PAH) compound, and a thermosetting epoxy was matrix was studied to interpret the reinforcing effect on the glass transition temperature ( Tg) by different routes: physical dispersion and/or covalent modification. The molecular dynamics of the relaxation processes were analyzed by broadband dielectric
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.
Universal Mechanism of Spin Relaxation in Solids

Science.gov (United States)

Chudnovsky, Eugene

2006-03-01

Conventional elastic theory ignores internal local twists and torques. Meantime, spin-lattice relaxation is inherently coupled with local elastic twists through conservation of the total angular momentum (spin + lattice). This coupling gives universal lower bound (free of fitting parameters) on the relaxation of the atomic or molecular spin in a solid [1] and on the relaxation of the electron spin in a quantum dot [2]. [1] E. M. Chudnovsky, D. A. Garanin, and R. Schilling, Phys. Rev. B 72, 094426 (2005). [2] C. Calero, E. M. Chudnovsky, and D. A. Garanin, Phys. Rev. Lett. 95, 166603 (2005).
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.
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.
Ghost lines in Moessbauer relaxation spectra

International Nuclear Information System (INIS)

Price, D.C.

1985-01-01

The appearance in Moessbauer relaxation spectra of 'ghost' lines, which are narrow lines that do not correspond to transitions between real hyperfine energy levels of the resonant system, is examined. It is shown that in many cases of interest, the appearance of these 'ghost' lines can be interpreted in terms of the relaxational averaging of one or more of the static interactions of the ion. (orig.)

A biotin-drug extraction and acid dissociation (BEAD) procedure to eliminate matrix and drug interference in a protein complex anti-drug antibody (ADA) isotype specific assay.

Science.gov (United States)

Niu, Hongmei; Klem, Thomas; Yang, Jinsong; Qiu, Yongchang; Pan, Luying

2017-07-01

Monitoring anti-drug antibody (ADA) responses in patients receiving protein therapeutics treatment is an important safety assessment for regulatory agencies, drug manufacturers, clinicians and patients. Recombinant human IGF-1/IGFBP-3 (rhIGF-1/rhIGFBP-3) is a 1:1 formulation of naturally occurring protein complex. The individual IGF-1 and IGFBP-3 proteins have multiple binding partners in serum matrix with high binding affinity to each other, which presents challenges in ADA assay development. We have developed a biotin-drug extraction with acid dissociation (BEAD) procedure followed by an electrochemiluminescence (ECL) direct assay to overcome matrix and drug interference. The method utilizes two step acid dissociation and excess biotin-drug to extract total ADA, which are further captured by soluble biotin-drug and detected in an ECL semi-homogeneous direct assay format. The pre-treatment method effectively eliminates interference by serum matrix and free drug, and enhances assay sensitivity. The assays passed acceptance criteria for all validation parameters, and have been used for clinical sample Ab testing. This method principle exemplifies a new approach for anti-isotype ADA assays, and could be an effective strategy for neutralizing antibody (NAb), pharmacokinetic (PK) and biomarker analysis in need of overcoming interference factors. Copyright © 2017 Elsevier B.V. All rights reserved.
Momentum and mass relaxation in heavy-ion collisions

International Nuclear Information System (INIS)

Gregoire, C.; Scheuter, F.; Remaud, B.; Sebille, F.

1984-01-01

The momentum and mass relaxation are shown to be described by transport equations. The momentum relaxation, which can be studied in the intermediate energy regime by the particle emissions, refers to a microscopic slowing down and diffusion process in the momentum space. The mass relaxation refers to the coupling of the collective mass asymmetry degree of freedom and the intrinsic system. It can be illustrated by the fast fission of light and very heavy systems
Dielectric relaxation and ac conductivity behaviour of polyvinyl alcohol–HgSe quantum dot hybrid films

International Nuclear Information System (INIS)

Sinha, Subhojyoti; Chatterjee, Sanat Kumar; Meikap, Ajit Kumar; Ghosh, Jiten

2014-01-01

Here we report a comparative study on the dielectric relaxation and ac conductivity behaviour of pure polyvinyl alcohol (PVA) and PVA–mercury selenide (HgSe) quantum dot hybrid films in the temperature range 298 K ⩽ T ⩽ 420 K and in the frequency range 100 Hz ⩽ f ⩽ 1 MHz. The prepared nanocomposite exhibits a larger dielectric constant as compared to the pure PVA. The real and imaginary parts of the dielectric constants were found to fit appreciably with the modified Cole–Cole equation, from which temperature-dependent values of the relaxation times, free charge carrier conductivity and space charge carrier conductivity were calculated. The relaxation time decreases with the quantum dot's inclusion in the PVA matrix and with an increase in temperature, whereas free charge carrier conductivity and space charge carrier conductivity increases with an increase in temperature. An increase in ac conductivity for the nanocomposites has also been observed, while the charge transport mechanism was found to follow the correlated barrier hopping model in both cases. An easy-path model with a suitable electrical equivalent circuit has been employed to analyse the temperature-dependent impedance spectra. The imaginary part of the complex electric modulus spectra exhibit an asymmetric nature and a non-Debye type of behaviour, which has been elucidated considering a generalized susceptibility function. The electric modulus spectra of the nanocomposite demonstrate a smaller amplitude and broader width, as compared to the pure PVA sample. (paper)
Communication: Relaxation-limited electronic currents in extended reservoir simulations

Science.gov (United States)

Gruss, Daniel; Smolyanitsky, Alex; Zwolak, Michael

2017-10-01

Open-system approaches are gaining traction in the simulation of charge transport in nanoscale and molecular electronic devices. In particular, "extended reservoir" simulations, where explicit reservoir degrees of freedom are present, allow for the computation of both real-time and steady-state properties but require relaxation of the extended reservoirs. The strength of this relaxation, γ, influences the conductance, giving rise to a "turnover" behavior analogous to Kramers turnover in chemical reaction rates. We derive explicit, general expressions for the weak and strong relaxation limits. For weak relaxation, the conductance increases linearly with γ and every electronic state of the total explicit system contributes to the electronic current according to its "reduced" weight in the two extended reservoir regions. Essentially, this represents two conductors in series—one at each interface with the implicit reservoirs that provide the relaxation. For strong relaxation, a "dual" expression-one with the same functional form-results, except now proportional to 1/γ and dependent on the system of interest's electronic states, reflecting that the strong relaxation is localizing electrons in the extended reservoirs. Higher order behavior (e.g., γ2 or 1/γ2) can occur when there is a gap in the frequency spectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a pseudo-plateau regime. These findings yield a physically motivated approach to diagnosing numerical simulations and understanding the influence of relaxation, and we examine their occurrence in both simple models and a realistic, fluctuating graphene nanoribbon.
Correlation of carrier localization with relaxation time distribution and electrical conductivity relaxation in silver-nanoparticle-embedded moderately doped polypyrrole nanostructures

Science.gov (United States)

Biswas, Swarup; Dutta, Bula; Bhattacharya, Subhratanu

2014-02-01

The electrical conductivity relaxation in moderately doped polypyrrole and its nanocomposites reinforced with different proportion of silver nanoparticles was investigated in both frequency and time domain. An analytical distribution function of relaxation times is constructed from the results obtained in the frequency domain formalism and is used to evaluate the Kohlrausch-Williams-Watts (KWW) type decay function in the time domain. The thermal evolution of different relaxation parameters was analyzed. The temperature-dependent dc electrical conductivity, estimated from the average conductivity relaxation time is observed to depend strongly on the nanoparticle loading and follows Mott three-dimensional variable range hopping (VRH) conduction mechanism. The extent of charge carrier localization calculated from the VRH mechanism is well correlated to the evidences obtained from the structural characterizations of different nanostructured samples.
Lifshitz quasinormal modes and relaxation from holography

NARCIS (Netherlands)

Sybesma, Watse|info:eu-repo/dai/nl/369283074; Vandoren, Stefan|info:eu-repo/dai/nl/304830739

2015-01-01

We obtain relaxation times for field theories with Lifshitz scaling and with holographic duals Einstein-Maxwell-Dilaton gravity theories. This is done by computing quasinormal modes of a bulk scalar field in the presence of Lifshitz black branes. We determine the relation between relaxation time and
State resolved vibrational relaxation modeling for strongly nonequilibrium flows

Science.gov (United States)

Boyd, Iain D.; Josyula, Eswar

2011-05-01

Vibrational relaxation is an important physical process in hypersonic flows. Activation of the vibrational mode affects the fundamental thermodynamic properties and finite rate relaxation can reduce the degree of dissociation of a gas. Low fidelity models of vibrational activation employ a relaxation time to capture the process at a macroscopic level. High fidelity, state-resolved models have been developed for use in continuum gas dynamics simulations based on computational fluid dynamics (CFD). By comparison, such models are not as common for use with the direct simulation Monte Carlo (DSMC) method. In this study, a high fidelity, state-resolved vibrational relaxation model is developed for the DSMC technique. The model is based on the forced harmonic oscillator approach in which multi-quantum transitions may become dominant at high temperature. Results obtained for integrated rate coefficients from the DSMC model are consistent with the corresponding CFD model. Comparison of relaxation results obtained with the high-fidelity DSMC model shows significantly less excitation of upper vibrational levels in comparison to the standard, lower fidelity DSMC vibrational relaxation model. Application of the new DSMC model to a Mach 7 normal shock wave in carbon monoxide provides better agreement with experimental measurements than the standard DSMC relaxation model.
On the Volterra integral equation relating creep and relaxation

International Nuclear Information System (INIS)

Anderssen, R S; De Hoog, F R; Davies, A R

2008-01-01

The evolving stress–strain response of a material to an applied deformation is causal. If the current response depends on the earlier history of the stress–strain dynamics of the material (i.e. the material has memory), then Volterra integral equations become the natural framework within which to model the response. For viscoelastic materials, when the response is linear, the dual linear Boltzmann causal integral equations are the appropriate model. The choice of one rather than the other depends on whether the applied deformation is a stress or a strain, and the associated response is, respectively, a creep or a relaxation. The duality between creep and relaxation is known explicitly and is referred to as the 'interconversion equation'. Rheologically, its importance relates to the fact that it allows the creep to be determined from knowledge of the relaxation and vice versa. Computationally, it has been known for some time that the recovery of the relaxation from the creep is more problematic than the creep from the relaxation. Recent research, using discrete models for the creep and relaxation, has confirmed that this is an essential feature of interconversion. In this paper, the corresponding result is generalized for continuous models of the creep and relaxation
Extracting energy and structure properties of glass-forming liquids from structural relaxation time.

Science.gov (United States)

Wang, Lianwen

2012-04-18

A comprehensive examination of the kinetic liquid model (Wang et al 2010 J. Phys.: Condens. Matter 22 455104) is carried out by fitting the structural relaxation time of 26 different glass-forming liquids in a wide temperature range, including most of the well-studied materials. Careful analysis of the compiled reported data reveals that experimental inaccuracies should not be overlooked in any 'benchmark test' of relating theories or models (e.g. in Lunkenheimer et al 2010 Phys. Rev. E 81 051504). The procedure, accuracy, ability, and efficiency of the kinetic liquid model are discussed in detail and in comparison with other available fitting methods. In general, the kinetic liquid model could be verified by 17 of the 26 compiled data sets and can serve as a meaningful approximative method for analyzing these liquids. Nonetheless, further experimental examinations in a wide temperature range are needed and are called for. Through fitting, the microscopic details of these liquids are extracted, namely, the enthalpy, entropy, and cooperativity in structural relaxation, which may facilitate further quantitative analysis to both the liquidus and glassy states of these materials.
Axisymmetric force-free states and relaxation of a spheroidal spheromak

International Nuclear Information System (INIS)

Throumoulopoulos, G.N.; Pantis, G.

1990-01-01

Axisymmetric force-free equilibrium eigenstates for a prolate as well as an oblate spheroidal Spheromak with arbitrary elongation are obtained. In the framework of the Woltjer-Taylor relaxation theory the relaxed states are also identified. A simple hypothesis for the relaxation process is introduced, which implies that the plasma relaxes from multitoroidal formations to a singly toroidal configuration, in qualitative agreement with experimental results. (author)
Axisymmetric force-free states and relaxation of a spheroidal spheromak

International Nuclear Information System (INIS)

Throumoulopoulos, G.N.; Pantis, G.

1990-01-01

Axisymmetric force-free equilibrium eigenstates for a prolate as well as an oblate spheroidal spheromak with arbitrary elongation are obtained. In the framework of the Woltjer-Taylor relaxation theory the relaxed states are also identified. A simple hypothesis for the relaxation process is introduced which implies that the plasma relaxes from multitoroidal formations to a singly toroidal configuration in qualitative agreement with experimental results. (Author)
Relaxation resistance of heat resisting alloys with cobalt

International Nuclear Information System (INIS)

Borzdyka, A.M.

1977-01-01

Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading
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.
Temperature dependence of the NMR spin-lattice relaxation rate for spin-1/2 chains

Science.gov (United States)

Coira, E.; Barmettler, P.; Giamarchi, T.; Kollath, C.

2016-10-01

We use recent developments in the framework of a time-dependent matrix product state method to compute the nuclear magnetic resonance relaxation rate 1 /T1 for spin-1/2 chains under magnetic field and for different Hamiltonians (XXX, XXZ, isotropically dimerized). We compute numerically the temperature dependence of the 1 /T1 . We consider both gapped and gapless phases, and also the proximity of quantum critical points. At temperatures much lower than the typical exchange energy scale, our results are in excellent agreement with analytical results, such as the ones derived from the Tomonaga-Luttinger liquid (TLL) theory and bosonization, which are valid in this regime. We also cover the regime for which the temperature T is comparable to the exchange coupling. In this case analytical theories are not appropriate, but this regime is relevant for various new compounds with exchange couplings in the range of tens of Kelvin. For the gapped phases, either the fully polarized phase for spin chains or the low-magnetic-field phase for the dimerized systems, we find an exponential decrease in Δ /(kBT ) of the relaxation time and can compute the gap Δ . Close to the quantum critical point our results are in good agreement with the scaling behavior based on the existence of free excitations.
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.
Estimating the two-particle $K$-matrix for multiple partial waves and decay channels from finite-volume energies

DEFF Research Database (Denmark)

Morningstar, Colin; Bulava, John; Singha, Bijit

2017-01-01

An implementation of estimating the two-to-two $K$-matrix from finite-volume energies based on the L\\"uscher formalism and involving a Hermitian matrix known as the "box matrix" is described. The method includes higher partial waves and multiple decay channels. Two fitting procedures for estimating...
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
Orbifolds and Exact Solutions of Strongly-Coupled Matrix Models

Science.gov (United States)

Córdova, Clay; Heidenreich, Ben; Popolitov, Alexandr; Shakirov, Shamil

2018-02-01

We find an exact solution to strongly-coupled matrix models with a single-trace monomial potential. Our solution yields closed form expressions for the partition function as well as averages of Schur functions. The results are fully factorized into a product of terms linear in the rank of the matrix and the parameters of the model. We extend our formulas to include both logarithmic and finite-difference deformations, thereby generalizing the celebrated Selberg and Kadell integrals. We conjecture a formula for correlators of two Schur functions in these models, and explain how our results follow from a general orbifold-like procedure that can be applied to any one-matrix model with a single-trace potential.
Vibrational relaxation in OCS mixtures

International Nuclear Information System (INIS)

Simpson, C.J.S.M.; Gait, P.D.; Simmie, J.M.

1976-01-01

Experimental measurements are reported of vibrational relaxation times which may be used to show whether there is near resonant vibration-rotation energy transfer between OCS and H 2 , D 2 or HD. Vibrational relaxation times have been measured in OCS and OCS mixtures over the temperature range 360 to 1000 K using a shock tube and a laser schlieren system. The effectiveness of the additives in reducing the relaxation time of OCS is in the order 4 He 3 He 2 2 and HD. Along this series the effect of an increase in temperature changes from the case of speeding up the rate with 4 He to retarding it with D 2 , HD and H 2 . There is no measurable difference in the effectiveness of n-D 2 and o-D 2 and little, or no, difference between n-H 2 and p-H 2 . Thus the experimental results do not give clear evidence for rotational-vibration energy transfer between hydrogen and OCS. This contrasts with the situation for CO 2 + H 2 mixtures. (author)

MODELING IN MAPLE AS THE RESEARCHING MEANS OF FUNDAMENTAL CONCEPTS AND PROCEDURES IN LINEAR ALGEBRA

Directory of Open Access Journals (Sweden)

Vasil Kushnir

2016-05-01

Full Text Available The article is devoted to binary technology and "fundamental training technology." Binary training refers to the simultaneous teaching of mathematics and computer science, for example differential equations and Maple, linear algebra and Maple. Moreover the system of traditional course of Maple is not performed. The use of the opportunities of Maple-technology in teaching mathematics is based on the following fundamental concepts of computer science as an algorithm, program, a linear program, cycle, branching, relative operators, etc. That’s why only a certain system of command operators in Maple is considered. They are necessary for fundamental concepts of linear algebra and differential equations studying in Maple-environment. Relative name - "the technology of fundamental training" reflects the study of fundamental mathematical concepts and procedures that express the properties of these concepts in Maple-environment. This article deals with the study of complex fundamental concepts of linear algebra (determinant of the matrix and algorithm of its calculation, the characteristic polynomial of the matrix and the eigenvalues of matrix, canonical form of characteristic matrix, eigenvectors of matrix, elementary divisors of the characteristic matrix, etc., which are discussed in the appropriate courses briefly enough, and sometimes are not considered at all, but they are important in linear systems of differential equations, asymptotic methods for solving differential equations, systems of linear equations. Herewith complex and voluminous procedures of finding of these linear algebra concepts embedded in Maple can be performed as a result of a simple command-operator. Especially important issue is building matrix to canonical form. In fact matrix functions are effectively reduced to the functions of the diagonal matrix or matrix in Jordan canonical form. These matrices are used to rise a square matrix to a power, to extract the roots of the n
Relaxation dispersion in MRI induced by fictitious magnetic fields.

Science.gov (United States)

Liimatainen, Timo; Mangia, Silvia; Ling, Wen; Ellermann, Jutta; Sorce, Dennis J; Garwood, Michael; Michaeli, Shalom

2011-04-01

A new method entitled Relaxation Along a Fictitious Field (RAFF) was recently introduced for investigating relaxations in rotating frames of rank ≥ 2. RAFF generates a fictitious field (E) by applying frequency-swept pulses with sine and cosine amplitude and frequency modulation operating in a sub-adiabatic regime. In the present work, MRI contrast is created by varying the orientation of E, i.e. the angle ε between E and the z″ axis of the second rotating frame. When ε > 45°, the amplitude of the fictitious field E generated during RAFF is significantly larger than the RF field amplitude used for transmitting the sine/cosine pulses. Relaxation during RAFF was investigated using an invariant-trajectory approach and the Bloch-McConnell formalism. Dipole-dipole interactions between identical (like) spins and anisochronous exchange (e.g., exchange between spins with different chemical shifts) in the fast exchange regime were considered. Experimental verifications were performed in vivo in human and mouse brain. Theoretical and experimental results demonstrated that changes in ε induced a dispersion of the relaxation rate constants. The fastest relaxation was achieved at ε ≈ 56°, where the averaged contributions from transverse components during the pulse are maximal and the contribution from longitudinal components are minimal. RAFF relaxation dispersion was compared with the relaxation dispersion achieved with off-resonance spin lock T(₁ρ) experiments. As compared with the off-resonance spin lock T(₁ρ) method, a slower rotating frame relaxation rate was observed with RAFF, which under certain experimental conditions is desirable. Copyright © 2011 Elsevier Inc. All rights reserved.
Importance of matrix inelastic deformations in the initial response of magnetic elastomers.

Science.gov (United States)

Sánchez, Pedro A; Gundermann, Thomas; Dobroserdova, Alla; Kantorovich, Sofia S; Odenbach, Stefan

2018-03-14

Being able to predict and understand the behaviour of soft magnetic materials paves the way to their technological applications. In this study we analyse the magnetic response of soft magnetic elastomers (SMEs) with magnetically hard particles. We present experimental evidence of a difference between the first and next magnetisation loops exhibited by these SMEs, which depends non-monotonically on the interplay between the rigidity of the polymer matrix, its mechanical coupling with the particles, and the magnetic interactions in the system. In order to explain the microstructural mechanism behind this behaviour, we used a minimal computer simulation model whose results evidence the importance of irreversible matrix deformations due to both translations and rotations of the particles. To confirm the simulation findings, computed tomography (CT) was used. We conclude that the initial exposure to the field triggers the inelastic matrix relaxation in the SMEs, as particles attempt to reorient. However, once the necessary degree of freedom is achieved, both the rotations and the magnetisation behaviour become stationary. We expect this scenario not only to be limited to the materials studied here, but also to apply to a broader class of hybrid SMEs.
Models of Flux Tubes from Constrained Relaxation

Indian Academy of Sciences (India)

tribpo

J. Astrophys. Astr. (2000) 21, 299 302. Models of Flux Tubes from Constrained Relaxation. Α. Mangalam* & V. Krishan†, Indian Institute of Astrophysics, Koramangala,. Bangalore 560 034, India. *e mail: mangalam @ iiap. ernet. in. † e mail: vinod@iiap.ernet.in. Abstract. We study the relaxation of a compressible plasma to ...
Modulation of drug release kinetics of shellac-based matrix tablets by in-situ polymerization through annealing process.

Science.gov (United States)

Limmatvapirat, Sontaya; Limmatvapirat, Chutima; Puttipipatkhachorn, Satit; Nunthanid, Jurairat; Luangtana-anan, Manee; Sriamornsak, Pornsak

2008-08-01

A new oral-controlled release matrix tablet based on shellac polymer was designed and developed, using metronidazole (MZ) as a model drug. The shellac-based matrix tablets were prepared by wet granulation using different amounts of shellac and lactose. The effect of annealing temperature and pH of medium on drug release from matrix tablets was investigated. The increased amount of shellac and increased annealing temperature significantly affected the physical properties (i.e., tablet hardness and tablet disintegration) and MZ release from the matrix tablets. The in-situ polymerization played a major role on the changes in shellac properties during annealing process. Though the shellac did not dissolve in acid medium, the MZ release in 0.1N HCl was faster than in pH 7.3 buffer, resulting from a higher solubility of MZ in acid medium. The modulation of MZ release kinetics from shellac-based matrix tablets could be accomplished by varying the amount of shellac or annealing temperature. The release kinetics was shifted from relaxation-controlled release to diffusion-controlled release when the amount of shellac or the annealing temperature was increased.
Comparison and extension of a direct model reference adaptive control procedure

Science.gov (United States)

Neat, Gregory W.; Kaufman, Howard; Steinvorth, Rodrigo

1992-01-01

This paper analyzes and extends an easily implemented direct model reference adaptive control procedure. The paper focuses on the major limitation of this control approach which is the satisfaction of a strictly positive real sufficiency condition in order to guarantee asymptotic tracking. Attempts, to date, to address this problem have been unable to relax simultaneously the stringent condition and maintain asymptotic tracking capabilities. Three different modifications to existing versions of this algorithm are presented which substantially relax the stringent sufficiency condition while providing asymptotic tracking. These three modifications achieve this goal by imposing slight adjustments to existing sufficiency conditions. A simulation example demonstrates that the modifications eliminate the steady error inherent in the existing methods.
Relaxation effect of abacavir on rat basilar arteries.

Directory of Open Access Journals (Sweden)

Rachel Wai Sum Li

Full Text Available The use of abacavir has been linked with increased cardiovascular risk in patients with human immunodeficiency virus infection; however, the mechanism involved remains unclear. We hypothesize that abacavir may impair endothelial function. In addition, based on the structural similarity between abacavir and adenosine, we propose that abacavir may affect vascular contractility through endogenous adenosine release or adenosine receptors in blood vessels.The relaxation effect of abacavir on rat basilar arteries was studied using the myograph technique. Cyclic GMP and AMP levels were measured by immunoassay. The effects of abacavir on nucleoside transporters were studied using radiolabeled nucleoside uptake experiments. Ecto-5' nucleotidase activity was determined by measuring the generation of inorganic phosphate using adenosine monophosphate as the substrate.Abacavir induced the relaxation of rat basilar arteries in a concentration-dependent manner. This relaxation was abolished when endothelium was removed. In addition, the relaxation was diminished by the nitric oxide synthase inhibitor, L-NAME, the guanylyl cyclase inhibitor, ODQ, and the protein kinase G inhibitor, KT5820. Abacavir also increased the cGMP level in rat basilar arteries. Abacavir-induced relaxation was also abolished by adenosine A2 receptor blockers. However, abacavir had no effect on ecto-5' nucleotidase and nucleoside transporters. Short-term and long-term treatment of abacavir did not affect acetylcholine-induced relaxation in rat basilar arteries.Abacavir induces acute endothelium-dependent relaxation of rat basilar arteries, probably through the activation of adenosine A2 receptors in endothelial cells, which subsequently leads to the release of nitric oxide, resulting in activation of the cyclic guanosine monophosphate/protein kinase G-dependent pathway in vascular smooth muscle cells. It is speculated that abacavir-induced cardiovascular risk may not be related to
Strategy BMT Al-Ittihad Using Matrix IE, Matrix SWOT 8K, Matrix SPACE and Matrix TWOS

Directory of Open Access Journals (Sweden)

Nofrizal Nofrizal

2018-03-01

Full Text Available This research aims to formulate and select BMT Al-Ittihad Rumbai strategy to face the changing of business environment both from internal environment such as organization resources, finance, member and external business such as competitor, economy, politics and others. This research method used Analysis of EFAS, IFAS, IE Matrix, SWOT-8K Matrix, SPACE Matrix and TWOS Matrix. our hope from this research it can assist BMT Al-Ittihad in formulating and selecting strategies for the sustainability of BMT Al-Ittihad in the future. The sample in this research is using purposive sampling technique that is the manager and leader of BMT Al-IttihadRumbaiPekanbaru. The result of this research shows that the position of BMT Al-Ittihad using IE Matrix, SWOT-8K Matrix and SPACE Matrix is in growth position, stabilization and aggressive. The choice of strategy after using TWOS Matrix is market penetration, market development, vertical integration, horizontal integration, and stabilization (careful.
Matrix Intensification Affects Body and Physiological Condition of Tropical Forest-Dependent Passerines.

Science.gov (United States)

Deikumah, Justus P; McAlpine, Clive A; Maron, Martine

2015-01-01

Matrix land-use intensification is a relatively recent and novel landscape change that can have important influences on the biota within adjacent habitat patches. While there are immediate local changes that it brings about, the influences on individual animals occupying adjacent habitats may be less evident initially. High-intensity land use could induce chronic stress in individuals in nearby remnants, leading ultimately to population declines. We investigated how physiological indicators and body condition measures of tropical forest-dependent birds differ between forest adjacent to surface mining sites and that near farmlands at two distances from remnant edge in southwest Ghana. We used mixed effects models of several condition indices including residual body mass and heterophil to lymphocyte (H/L) ratios (an indicator of elevated chronic stress) to explore the effect of matrix intensity on forest-dependent passerines classed as either sedentary area-sensitive habitat specialists or nomadic generalists. Individual birds occupying tropical forest remnants near surface mining sites were in poorer condition, as indicated by lower residual body mass and elevated chronic stress, compared to those in remnants near agricultural lands. The condition of the sedentary forest habitat specialists white-tailed alethe, Alethe diademata and western olive sunbird, Cyanomitra obscura was most negatively affected by high-intensity surface mining land-use adjacent to remnants, whereas generalist species were not affected. Land use intensification may set in train a new trajectory of faunal relaxation beyond that expected based on habitat loss alone. Patterns of individual condition may be useful in identifying habitats where species population declines may occur before faunal relaxation has concluded.
Atosiban versus fenoterol as a uterine relaxant for external cephalic version: randomised controlled trial.

Science.gov (United States)

Velzel, Joost; Vlemmix, Floortje; Opmeer, Brent C; Molkenboer, Jan F M; Verhoeven, Corine J; van Pampus, Mariëlle G; Papatsonis, Dimitri N M; Bais, Joke M J; Vollebregt, Karlijn C; van der Esch, Liesbeth; Van der Post, Joris A M; Mol, Ben Willem; Kok, Marjolein

2017-01-26

To compare the effectiveness of the oxytocin receptor antagonist atosiban with the beta mimetic fenoterol as uterine relaxants in women undergoing external cephalic version (ECV) for breech presentation. Multicentre, open label, randomised controlled trial. Eight hospitals in the Netherlands, August 2009 to May 2014. 830 women with a singleton fetus in breech presentation and a gestational age of more than 34 weeks were randomly allocated in a 1:1 ratio to either 6.75 mg atosiban (n=416) or 40 μg fenoterol (n=414) intravenously for uterine relaxation before ECV. The primary outcome measures were a fetus in cephalic position 30 minutes after the procedure and cephalic presentation at delivery. Secondary outcome measures were mode of delivery, incidence of fetal and maternal complications, and drug related adverse events. All analyses were done on an intention-to-treat basis. Cephalic position 30 minutes after ECV occurred significantly less in the atosiban group than in the fenoterol group (34% v 40%, relative risk 0.73, 95% confidence interval 0.55 to 0.93). Presentation at birth was cephalic in 35% (n=139) of the atosiban group and 40% (n=166) of the fenoterol group (0.86, 0.72 to 1.03), and caesarean delivery was performed in 60% (n=240) of women in the atosiban group and 55% (n=218) in the fenoterol group (1.09, 0.96 to 1.20). No significant differences were found in neonatal outcomes or drug related adverse events. In women undergoing ECV for breech presentation, uterine relaxation with fenoterol increases the rate of cephalic presentation 30 minutes after the procedure. No statistically significant difference was found for cephalic presentation at delivery. Dutch Trial Register, NTR 1877. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Irradiation creep, stress relaxation and a mechanical equation of state

International Nuclear Information System (INIS)

Foster, J.P.

1976-01-01

Irradiation creep and stress relaxation data are available from the United Kingdom for 20 percent CW M316, 20 percent CW FV 548 and FHT PE16 using pure torsion in the absence of swelling at 300 0 C. Irradiation creep models were used to calculate the relaxation and permanent deflection of the stress relaxation tests. Two relationships between irradiation creep and stress relaxation were assessed by comparing the measured and calculated stress relaxation and permanent deflection. The results show that for M316 and FV548, the stress relaxation and deflection may be calculated using irradiation creep models when the stress rate term arising from the irradiation creep model is set equal to zero. In the case of PE16, the inability to calculate the stress relaxation and permanent deflection from the irradiation creep data was attributed to differences in creep behavior arising from lot-to-lot variations in alloying elements and impurity content. A modification of the FV548 and PE16 irradiation creep coefficients was necessary in order to calculate the stress relaxation and deflection. The modifications in FV548 and PE16 irradiation creep properties reduces the large variation in the transient or incubation parameter predicted by irradiation creep tests for M316, FV548 and PE16
Dielectric relaxation in Yb-doped SrZrO3

International Nuclear Information System (INIS)

Kamishima, O; Abe, Y; Ishii, T; Kawamura, J; Hattori, T

2004-01-01

The dielectric constant of the proton conductor SrZr 1-x Yb x O 3 (x 0-0.1) was measured as a function of temperature and frequency. Two well-defined relaxation peaks were observed in SrZrO 3 doped with more than 1 mol% of Yb. The assignment of the two dielectric relaxations is discussed in terms of IR spectra and by free energy calculation for a miscibility of dopant Yb ions. The Yb concentration dependence of the relaxation strength of the two dielectric relaxations is in agreement with the results calculated from the free energy. The two relaxations can be assigned to a reorientation of a single Yb-OH dipole and of Yb-OH dipoles associated with Yb-clusters. The attractive energy for Yb-clustering in SrZrO 3 is evaluated at about -85 meV
Mechanism of nuclear cross-relaxation in magnetically ordered media

Energy Technology Data Exchange (ETDEWEB)

Buishvili, L L; Volzhan, E B; Giorgadze, N P [AN Gruzinskoj SSR, Tbilisi. Inst. Fiziki

1975-09-01

A mechanism of two-step nuclear relaxation in magnetic ordered dielectrics is proposed. The case is considered where the energy conservation in the cross relaxation (CR) process is ensured by the lattice itself without spin-spin interactions. Expressions have been obtained describing the temperature dependence of the CR rate. For a nonuniform broadened NMR line it has been shown that the spin-lattice relaxation time for a spin packet taken out from the equilibrium may be determined by the CR time owing to the mechanism suggested. When the quantization axes for electron and nuclear spins coincide, the spin-lattice relaxation is due to the three-magnon mechanism. The cross-relaxation stage has been shown to play a significant role in the range of low temperatures (T<10 deg K) and to become negligible with a temperature increase.
Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

Science.gov (United States)

Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

2012-06-06

Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great
Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

Science.gov (United States)

Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

2012-01-01

Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential
Filamin A Mediates Wound Closure by Promoting Elastic Deformation and Maintenance of Tension in the Collagen Matrix

Science.gov (United States)

Mohammadi, Hamid; Pinto, Vanessa I.; Wang, Yongqiang; Hinz, Boris; Janmey, Paul A.; McCulloch, Christopher A.

2016-01-01

Cell-mediated remodeling and wound closure are critical for efficient wound healing, but the contribution of actin-binding proteins to contraction of the extracellular matrix is not defined. We examined the role of filamin A (FLNa), an actin filament cross-linking protein, in wound contraction and maintenance of matrix tension. Conditional deletion of FLNa in fibroblasts in mice was associated with ~ 4 day delay of full-thickness skin wound contraction compared with wild-type (WT) mice. We modeled the healing wound matrix using cultured fibroblasts plated on grid-supported collagen gels that create lateral boundaries, which are analogues to wound margins. In contrast to WT cells, FLNa knockdown (KD) cells could not completely maintain tension when matrix compaction was resisted by boundaries, which manifested as relaxed matrix tension. Similarly, WT cells on cross-linked collagen, which requires higher levels of sustained tension, exhibited approximately fivefold larger deformation fields and approximately twofold greater fiber alignment compared with FLNa KD cells. Maintenance of boundary-resisted tension markedly influenced the elongation of cell extensions: in WT cells, the number (~50%) and length (~300%) of cell extensions were greater than FLNa KD cells. We conclude that FLNa is required for wound contraction, in part by enabling elastic deformation and maintenance of tension in the matrix. PMID:26134946
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)
EVALUATION OF A BUFFERED SOLID PHASE DISPERSION PROCEDURE ADAPTED FOR PESTICIDE ANALYSES IN THE SOIL MATRIX

Directory of Open Access Journals (Sweden)

Ana María Domínguez

2015-08-01

Full Text Available An evaluation of the pesticides extracted from the soil matrix was conducted using a citrate-buffered solid phase dispersion sample preparation method (QuEChERS. The identification and quantitation of pesticide compounds was performed using gas chromatography-mass spectrometry. Because of the occurrence of the matrix effect in 87% of the analyzed pesticides, the quantification was performed using matrix-matched calibration. The method's quantification limits were between 0.01 and 0.5 mg kg-1. Repeatability and intermediate precision, expressed as a relative standard deviation percentage, were less than 20%. The recoveries in general ranged between 62% and 99%, with a relative standard deviation < 20%. All the responses were linear, with a correlation coefficient (r ≥0.99.
The Effect of Massage on Anticipatory Anxiety and Procedural Pain in Patients with Burn Injury.

Science.gov (United States)

Najafi Ghezeljeh, Tahereh; Mohades Ardebili, Fatimah; Rafii, Forough; Manafi, Farzad

2017-01-01

Pain related to burn injuries is one of the most troublesome pain intensity. This study aimed to investigate the effect of massage on anticipatory anxiety, procedural pain intensity, vital signs and relaxation level of patients with burn injury. In this quasi-experimental study, through convenience sampling, 60 hospitalized adult burn patients were selected from a specialized burn and reconstructive hospital. Subjects were assigned to massage and control groups through simple randomization. Massage was offered by using non aromatic oil about 10-15 minutes before wound care on intact part of the body once a day for 20 minutes on patients' bedside for 3 consecutive days. In the 3 days, the control group did not received any massage and were asked to stay at bed. Demographic and clinical characteristics and vital signs, Visual Analogue Scale and the Persian version of Burn Specific Pain Anxiety Scale were used to determine baseline and procedural pain, anxiety and relaxation levels and anticipatory anxiety. No significant difference was noted between mean score of pain intensity, anxiety and relaxation level, and vital signs in massage and control groups after intervention following wound care. In massage and control groups, there was no significant differences between mean scores of anticipatory anxiety before and after intervention. There was no significant difference between the mean scores of anticipatory anxiety in massage and control groups after intervention prior wound care. Massage was shown not to have any effect on anticipatory anxiety and procedural pain.
Regularities of intermediate adsorption complex relaxation

International Nuclear Information System (INIS)

Manukova, L.A.

1982-01-01

The experimental data, characterizing the regularities of intermediate adsorption complex relaxation in the polycrystalline Mo-N 2 system at 77 K are given. The method of molecular beam has been used in the investigation. The analytical expressions of change regularity in the relaxation process of full and specific rates - of transition from intermediate state into ''non-reversible'', of desorption into the gas phase and accumUlation of the particles in the intermediate state are obtained

U matrix construction for Quantum Chromodynamics through Dirac brackets

International Nuclear Information System (INIS)

Santos, M.A. dos.

1987-09-01

A procedure for obtaining the U matrix using Dirac brackets, recently developed by Kiefer and Rothe, is applied for Quantum Chromodynamics. The correspondent interaction Lagrangian is the same obtained by Schwinger, Christ and Lee, using independent methods. (L.C.J.A.)
Dependence of Brownian and Néel relaxation times on magnetic field strength

International Nuclear Information System (INIS)

Deissler, Robert J.; Wu, Yong; Martens, Michael A.

2014-01-01

Purpose: In magnetic particle imaging (MPI) and magnetic particle spectroscopy (MPS) the relaxation time of the magnetization in response to externally applied magnetic fields is determined by the Brownian and Néel relaxation mechanisms. Here the authors investigate the dependence of the relaxation times on the magnetic field strength and the implications for MPI and MPS. Methods: The Fokker–Planck equation with Brownian relaxation and the Fokker–Planck equation with Néel relaxation are solved numerically for a time-varying externally applied magnetic field, including a step-function, a sinusoidally varying, and a linearly ramped magnetic field. For magnetic fields that are applied as a step function, an eigenvalue approach is used to directly calculate both the Brownian and Néel relaxation times for a range of magnetic field strengths. For Néel relaxation, the eigenvalue calculations are compared to Brown's high-barrier approximation formula. Results: The relaxation times due to the Brownian or Néel mechanisms depend on the magnitude of the applied magnetic field. In particular, the Néel relaxation time is sensitive to the magnetic field strength, and varies by many orders of magnitude for nanoparticle properties and magnetic field strengths relevant for MPI and MPS. Therefore, the well-known zero-field relaxation times underestimate the actual relaxation times and, in particular, can underestimate the Néel relaxation time by many orders of magnitude. When only Néel relaxation is present—if the particles are embedded in a solid for instance—the authors found that there can be a strong magnetization response to a sinusoidal driving field, even if the period is much less than the zero-field relaxation time. For a ferrofluid in which both Brownian and Néel relaxation are present, only one relaxation mechanism may dominate depending on the magnetic field strength, the driving frequency (or ramp time), and the phase of the magnetization relative to the
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
Development of a pericardial acellular matrix biomaterial: biochemical and mechanical effects of cell extraction.

Science.gov (United States)

Courtman, D W; Pereira, C A; Kashef, V; McComb, D; Lee, J M; Wilson, G J

1994-06-01

There is evidence to suggest that the cellular components of homografts and bioprosthetic xenografts may contribute to calcification or immunogenic reactions. A four-step detergent and enzymatic extraction process has been developed to remove cellular components from bovine pericardial tissue. The process results in an acellular matrix material consisting primarily of elastin, insoluble collagen, and tightly bound glycosaminoglycans. Light and electron microscopy confirmed that nearly all cellular constituents are removed without ultrastructural evidence of damage to fibrous components. Collagen denaturation temperatures remained unaltered. Biochemical analysis confirmed the retention of collagen and elastin and some differential extraction of glycosaminoglycans. Low strain rate fracture testing and high strain rate viscoelastic characterization showed that, with the exception of slightly increased stress relaxation, the mechanical properties of the fresh tissue were preserved in the pericardial acellular matrix. Crosslinking of the material in glutaraldehyde or poly(glycidyl ether) produced mechanical changes consistent with the same treatments of fresh tissue. The pericardial acellular matrix is a promising approach to the production of biomaterials for heart valve or cardiovascular patching applications.
Super-Relaxed ( -Proximal Point Algorithms, Relaxed ( -Proximal Point Algorithms, Linear Convergence Analysis, and Nonlinear Variational Inclusions

Directory of Open Access Journals (Sweden)

Agarwal RaviP

2009-01-01

Full Text Available We glance at recent advances to the general theory of maximal (set-valued monotone mappings and their role demonstrated to examine the convex programming and closely related field of nonlinear variational inequalities. We focus mostly on applications of the super-relaxed ( -proximal point algorithm to the context of solving a class of nonlinear variational inclusion problems, based on the notion of maximal ( -monotonicity. Investigations highlighted in this communication are greatly influenced by the celebrated work of Rockafellar (1976, while others have played a significant part as well in generalizing the proximal point algorithm considered by Rockafellar (1976 to the case of the relaxed proximal point algorithm by Eckstein and Bertsekas (1992. Even for the linear convergence analysis for the overrelaxed (or super-relaxed ( -proximal point algorithm, the fundamental model for Rockafellar's case does the job. Furthermore, we attempt to explore possibilities of generalizing the Yosida regularization/approximation in light of maximal ( -monotonicity, and then applying to first-order evolution equations/inclusions.
Relaxation property of the fractional Brownian particle

International Nuclear Information System (INIS)

Wang Litan; Lung, C.W.

1988-08-01

Dynamic susceptibility of a diffusion system associated with the fractional Brownian motion (fBm) was examined for the fractal property of the Non-Debye relaxation process. The comparisons between fBm and other approaches were made. Anomalous diffusion and the Non-Debye relaxation processes were discussed with this approach. (author). 8 refs, 1 fig
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
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.
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.
Muon spin relaxation in ferromagnets. Pt. 1

International Nuclear Information System (INIS)

Lovesey, S.W.; Karlsson, E.B.

1991-04-01

Expressions for the dipolar and hyperfine contributions to the relaxation rate of muons implanted in a ferromagnet are presented and analysed using the Heisenberg model of spin-waves including dipolar and Zeeman energies. Calculations for EuO indicate that relaxation is likely to be dominated by the hyperfine mechanism, even if the ratio of the hyperfine and dipolar coupling constants is small. The hyperfine mechanism is sensitive to the dipolar energy of the atomic spins, whereas the dipolar mechanisms depend essentially on the exchange energy. For both mechanisms there is an almost quadratic dependence on temperature, throughout much of the ordered magnetic phase, which reflects two-spin-wave difference events from the Raman-type relaxation processes. (author)
Relaxation of Isolated Ventricular Cardiomyocytes by a Voltage-Dependent Process

Science.gov (United States)

Bridge, John H. B.; Spitzer, Kenneth W.; Ershler, Philip R.

1988-08-01

Cell contraction and relaxation were measured in single voltage-clamped guinea pig cardiomyocytes to investigate the contribution of sarcolemmal Na+-Ca2+ exchange to mechanical relaxation. Cells clamped from -80 to 0 millivolts displayed initial phasic and subsequent tonic contractions; caffeine reduced or abolished the phasic and enlarged the tonic contraction. The rate of relaxation from tonic contractions was steeply voltage-dependent and was significantly slowed in the absence of a sarcolemmal Na+ gradient. Tonic contractions elicited in the absence of a Na+ gradient promptly relaxed when external Na+ was applied, reflecting activation of Na+-Ca2+ exchange. It appears that a voltage-dependent Na+-Ca2+ exchange can rapidly mechanically relax mammalian heart muscle.
Holographic grating relaxation technique for soft matter science

Energy Technology Data Exchange (ETDEWEB)

Lesnichii, Vasilii, E-mail: vasilii.lesnichii@physchem.uni-freiburg.de [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); ITMO University, Kronverksky prospekt 49, Saint-Petersburg 197101 (Russian Federation); Kiessling, Andy [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); Current address: Illinois Institute of Technology, 10 West 33rd Street, Chicago,IL60616 (United States); Bartsch, Eckhard [Institute of Physical Chemistry, Albertstraße 21, Institute of Macromolecular Chemistry, Stefan-Meier-Str. 31, Albert-Ludwigs Universität, Freiburg im Breisgau 79104 (Germany); Veniaminov, Andrey, E-mail: veniaminov@phoi.ifmo.ru [ITMO University, Kronverksky prospekt 49, Saint-Petersburg 197101 (Russian Federation)

2016-06-17

The holographic grating relaxation technique also known as forced Rayleigh scattering consists basically in writing a holographic grating in the specimen of interest and monitoring its diffraction efficiency as a function of time, from which valuable information on mass or heat transfer and photoinduced transformations can be extracted. In a more detailed view, the shape of the relaxation curve and the relaxation rate as a function of the grating period were found to be affected by the architecture of diffusing species (molecular probes) that constitute the grating, as well as that of the environment they diffuse in, thus making it possible to access and study spatial heterogeneity of materials and different modes of e.g., polymer motion. Minimum displacements and spatial domains approachable by the technique are in nanometer range, well below spatial periods of holographic gratings. In the present paper, several cases of holographic relaxation in heterogeneous media and complex motions are exemplified. Nano- to micro-structures or inhomogeneities comparable in spatial scale with holographic gratings manifest themselves in relaxation experiments via non-exponential decay (stepwise or stretched), spatial-period-dependent apparent diffusion coefficient, or unusual dependence of diffusion coefficient on molecular volume of diffusing probes.
Abrupt relaxation in high-spin molecules

International Nuclear Information System (INIS)

Chang, C.-R.; Cheng, T.C.

2000-01-01

Mean-field model suggests that the rate of resonant quantum tunneling in high-spin molecules is not only field-dependent but also time-dependent. The relaxation-assisted resonant tunneling in high-spin molecules produces an abrupt magnetization change during relaxation. When the applied field is very close to the resonant field, a time-dependent interaction field gradually shifts the energies of different collective spin states, and magnetization tunneling is observed as two energies of the spin states coincide
Stress relaxation behavior and mechanism of AEREX350 and Waspaloy superalloys

Energy Technology Data Exchange (ETDEWEB)

Wang, Yuzhou; Dong, Jianxin; Zhang, Maicang; Yao, Zhihao

2016-12-15

The relaxation properties of AEREX350 and Waspaloy were studied contrastively at temperatures ranging from 600 °C to 800 °C with the same initial stress 510 MPa. The relationship between the microstructure and relaxation properties was elucidated using scanning and transmission electron microscopy techniques. It was found that the relaxation limit and relaxation stability of the two alloys decreased obviously with the increase of temperature, but the relaxation stability of AEREX350 decreased more slowly compared with Waspaloy. Further investigations show that the relaxation behavior is mainly depended on both precipitate characteristics and its interaction with dislocations. The complex precipitates evolution of AEREX350 alloy leads to a higher relaxation limit at high temperature 800 °C, but more quantity of γ′ in Waspaloy results in a higher relaxation limit at the low temperature of 600 °C. Thus it is suggested that as fastener alloys, Waspaloy is more suitable for low temperature service while AEREX350 is the preferred choice for high temperature service.
Optimization of transversal relaxation of nitroxides for pulsed electron-electron double resonance spectroscopy in phospholipid membranes.

Science.gov (United States)

Dastvan, Reza; Bode, Bela E; Karuppiah, Muruga Poopathi Raja; Marko, Andriy; Lyubenova, Sevdalina; Schwalbe, Harald; Prisner, Thomas F

2010-10-28

Pulsed electron-electron double resonance (PELDOR) spectroscopy is increasingly applied to spin-labeled membrane proteins. However, after reconstitution into liposomes, spin labels often exhibit a much faster transversal relaxation (T(m)) than in detergent micelles, thus limiting application of the method in lipid bilayers. In this study, the main reasons for enhanced transversal relaxation in phospholipid membranes were investigated systematically by use of spin-labeled derivatives of stearic acid and phosphatidylcholine as well as spin-labeled derivatives of the channel-forming peptide gramicidin A under the conditions typically employed for PELDOR distance measurements. Our results clearly show that dephasing due to instantaneous diffusion that depends on dipolar interaction among electron spins is an important contributor to the fast echo decay in cases of high local concentrations of spin labels in membranes. The main difference between spin labels in detergent micelles and membranes is their local concentration. Consequently, avoiding spin clustering and suppressing instantaneous diffusion is the key step for maximizing PELDOR sensitivity in lipid membranes. Even though proton spin diffusion is an important relaxation mechanism, only in samples of low local concentrations does deuteration of acyl chains and buffer significantly prolong T(m). In these cases, values of up to 7 μs have been achieved. Furthermore, our study revealed that membrane composition and labeling position in the membrane can also affect T(m), either by promoting the segregation of spin-labeled species or by altering their exposure to matrix protons. Effects of other experimental parameters including temperature (<50 K), presence of oxygen, and cryoprotectant type are negligible under our experimental conditions.
Excited-state relaxation of some aminoquinolines

Directory of Open Access Journals (Sweden)

2006-01-01

Full Text Available The absorption and fluorescence spectra, fluorescence quantum yields and lifetimes, and fluorescence rate constants ( k f of 2-amino-3-( 2 ′ -benzoxazolylquinoline (I, 2-amino-3-( 2 ′ -benzothiazolylquinoline (II, 2-amino-3-( 2 ′ -methoxybenzothiazolyl-quinoline (III, 2-amino-3-( 2 ′ -benzothiazolylbenzoquinoline (IV at different temperatures have been measured. The shortwavelength shift of fluorescence spectra of compounds studied (23–49 nm in ethanol as the temperature decreases (the solvent viscosity increases points out that the excited-state relaxation process takes place. The rate of this process depends essentially on the solvent viscosity, but not the solvent polarity. The essential increasing of fluorescence rate constant k f (up to about 7 times as the solvent viscosity increases proves the existence of excited-state structural relaxation consisting in the mutual internal rotation of molecular fragments of aminoquinolines studied, followed by the solvent orientational relaxation.
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’...
Electron spin-lattice relaxation in fractals

International Nuclear Information System (INIS)

Shrivastava, K.N.

1986-08-01

We have developed the theory of the spin-fracton interaction for paramagnetic ions in fractal structures. The interaction is exponentially damped by the self-similarity length of the fractal and by the range dimensionality d Φ . The relaxation time of the spin due to the absorption and emission of the fracton has been calculated for a general dimensionality called the Raman dimensionality d R , which for the fractons differs from the Hausdorff (fractal) dimensionality, D, as well as from the Euclidean dimensionality, d. The exponent of the energy level separation in the relaxation rate varies with d R d Φ /D. We have calculated the spin relaxation rate due to a new type of Raman process in which one fracton is absorbed to affect a spin transition from one electronic level to another and later another fracton is emitted along with a spin transition such that the difference in the energies of the two fractons is equal to the electronic energy level separation. The temperature and the dimensionality dependence of such a process has been found in several approximations. In one of the approximations where the van Vleck relaxation rate for a spin in a crystal is known to vary with temperature as T 9 , our calculated variation for fractals turns out to be T 6.6 , whereas the experimental value for Fe 3+ in frozen solutions of myoglobin azide is T 6.3 . Since we used d R =4/3 and the fracton range dimensionality d Φ =D/1.8, we expect to measure the dimensionalities of the problem by measuring the temperature dependence of the relaxation times. We have also calculated the shift of the paramagnetic resonance transition for a spin in a fractal for general dimensionalities. (author)
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
Progress in the application of classical S-matrix theory to inelastic collision processes

International Nuclear Information System (INIS)

McCurdy, C.W.; Miller, W.H.

1980-01-01

Methods are described which effectively solve two of the technical difficulties associated with applying classical S-matrix theory to inelastic/reactive scattering. Specifically, it is shown that rather standard numerical methods can be used to solve the ''root search'' problem (i.e., the nonlinear boundary value problem necessary to impose semiclassical quantum conditions at the beginning and the end of the classical trajectories) and also how complex classical trajectories, which are necessary to describe classically forbidden (i.e., tunneling) processes, can be computed in a numerically stable way. Application is made to vibrational relaxation of H 2 by collision with He (within the helicity conserving approximation). The only remaining problem with regard to applying classical S-matrix theory to complex collision processes has to do with the availability of multidimensional uniform asymptotic formulas for interpolating the ''primitive'' semiclassical expressions between their various regions of validity

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
On low cycle fatigue in metal matrix composites

DEFF Research Database (Denmark)

Pedersen, Thomas Ø; Tvergaard, Viggo

2000-01-01

A numerical cell model analysis is used to study the development of fatigue damage in aluminium reinforced by aligned, short SiC fibres. The material is subjected to cyclic loading with either stress control or strain control, and the matrix material is represented by a cyclic plasticity model......, in which continuum damage mechanics is incorporated to model fatigue damage evolution. This material model uses a superposition of kinematic and isotropic hardening, and is able to account for the Bauschinger effect as well as ratchetting, mean stress relaxation, and cyclic hardening or softening. The cell...... model represents a material with transversely staggered fibres. With focus on low cyclic fatigue, the effect of different fibre aspect ratios, different triaxial stress states, and balanced as well as unbalanced cyclic loading is studied....
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.
Hybrid transfer-matrix FDTD method for layered periodic structures.

Science.gov (United States)

Deinega, Alexei; Belousov, Sergei; Valuev, Ilya

2009-03-15

A hybrid transfer-matrix finite-difference time-domain (FDTD) method is proposed for modeling the optical properties of finite-width planar periodic structures. This method can also be applied for calculation of the photonic bands in infinite photonic crystals. We describe the procedure of evaluating the transfer-matrix elements by a special numerical FDTD simulation. The accuracy of the new method is tested by comparing computed transmission spectra of a 32-layered photonic crystal composed of spherical or ellipsoidal scatterers with the results of direct FDTD and layer-multiple-scattering calculations.
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.
Thermally induced magnetic relaxation in square artificial spin ice

Science.gov (United States)

Andersson, M. S.; Pappas, S. D.; Stopfel, H.; Östman, E.; Stein, A.; Nordblad, P.; Mathieu, R.; Hjörvarsson, B.; Kapaklis, V.

2016-11-01

The properties of natural and artificial assemblies of interacting elements, ranging from Quarks to Galaxies, are at the heart of Physics. The collective response and dynamics of such assemblies are dictated by the intrinsic dynamical properties of the building blocks, the nature of their interactions and topological constraints. Here we report on the relaxation dynamics of the magnetization of artificial assemblies of mesoscopic spins. In our model nano-magnetic system - square artificial spin ice - we are able to control the geometrical arrangement and interaction strength between the magnetically interacting building blocks by means of nano-lithography. Using time resolved magnetometry we show that the relaxation process can be described using the Kohlrausch law and that the extracted temperature dependent relaxation times of the assemblies follow the Vogel-Fulcher law. The results provide insight into the relaxation dynamics of mesoscopic nano-magnetic model systems, with adjustable energy and time scales, and demonstrates that these can serve as an ideal playground for the studies of collective dynamics and relaxations.
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.
Minimally invasive esthetic ridge preservation with growth-factor enhanced bone matrix.

Science.gov (United States)

Nevins, Marc L; Said, Sherif

2017-12-28

Extraction socket preservation procedures are critical to successful esthetic implant therapy. Conventional surgical approaches are technique sensitive and often result in alteration of the soft tissue architecture, which then requires additional corrective surgical procedures. This case series report presents the ability of flapless surgical techniques combined with a growth factor-enhanced bone matrix to provide esthetic ridge preservation at the time of extraction for compromised sockets. When considering esthetic dental implant therapy, preservation, or further enhancement of the available tissue support at the time of tooth extraction may provide an improved esthetic outcome with reduced postoperative sequelae and decreased treatment duration. Advances in minimally invasive surgical techniques combined with recombinant growth factor technology offer an alternative for bone reconstruction while maintaining the gingival architecture for enhanced esthetic outcome. The combination of freeze-dried bone allograft (FDBA) and rhPDGF-BB (platelet-derived growth factor-BB) provides a growth-factor enhanced matrix to induce bone and soft tissue healing. The use of a growth-factor enhanced matrix is an option for minimally invasive ridge preservation procedures for sites with advanced bone loss. Further studies including randomized clinical trials are needed to better understand the extent and limits of these procedures. The use of minimally invasive techniques with growth factors for esthetic ridge preservation reduces patient morbidity associated with more invasive approaches and increases the predictability for enhanced patient outcomes. By reducing the need for autogenous bone grafts the use of this technology is favorable for patient acceptance and ease of treatment process for esthetic dental implant therapy. © 2017 Wiley Periodicals, Inc.
Resonant tunneling measurements of size-induced strain relaxation

Science.gov (United States)

Akyuz, Can Deniz

Lattice mismatch strain available in such semiconductor heterostructures as Si/SiGe or GaAs/AlGaAs can be employed to alter the electronic and optoelectronic properties of semiconductor structures and devices. When deep submicron structures are fabricated from strained material, strained layers relax by sidewall expansion giving rise to size- and geometry-dependent strain gradients throughout the structure. This thesis describes a novel experimental technique to probe the size-induced strain relaxation by studying the tunneling current characteristics of strained p-type Si/SiGe resonant tunneling diodes. Our current-voltage measurements on submicron strained p-Si/SiGe double- and triple-barrier resonant tunneling structures as a function of device diameter, D, provide experimental access to both the average strain relaxation (which leads to relative shifts in the tunneling current peak positions) and strain gradients (which give rise to a fine structure in the current peaks due to inhomogeneous strain-induced lateral quantization). We find that strain relaxation is significant, with a large fraction of the strain energy relaxed on average in D ≤ 0.25 m m devices. Further, the in-plane potentials that arise from inhomogeneous strain gradients are large. In the D ˜ 0.2 m m devices, the corresponding lateral potentials are approximately parabolic exceeding ˜ 25 meV near the perimeter. These potentials create discrete hole states in double-barrier structures (single well), and coupled hole states in triple-barrier structures (two wells). Our results are in excellent agreement with finite-element strain calculations in which the strained layers are permitted to relax to a state of minimum energy by sidewall expansion. Size-induced strain relaxation will undoubtedly become a serious technological issue once strained devices are scaled down to the deep submicron regime. Interestingly, our calculations predict and our measurements are consistent with the appearance of
Compliance matrix for the mixed waste disposal facilities, Trenches 31 ampersand 34, burial ground 218-W-5

International Nuclear Information System (INIS)

Carlyle, D.W.

1994-01-01

The purpose of the Trench 31 ampersand 34 Mixed Waste Disposal Facility Compliance Matrix is to provide objective evidence of implementation of all regulatory and procedural-institutional requirements for the disposal facilities. This matrix provides a listing of the individual regulatory and procedural-institutional requirements that were addressed. Subject matter experts reviewed pertinent documents that had direct or indirect impact on the facility. Those found to be applicable were so noted and listed in Appendix A. Subject matter experts then extracted individual requirements from the documents deemed applicable and listed them in the matrix tables. The results of this effort are documented in Appendix B
Vogel-Fulcher dependence of relaxation rates in a nematic monomer and elastomer

Science.gov (United States)

Shenoy, D.; Filippov, S.; Aliev, F.; Keller, P.; Thomsen, D.; Ratna, B.

2000-12-01

Dielectric relaxation spectroscopy is used to study the relaxation processes in a nematic monomer and the corresponding cross-linked polymer nematic liquid crystal (elastomer). In the frequency window 10 mHz to 2 GHz the monomer liquid crystal shows a single relaxation whereas the polymer exhibits three relaxation processes, two of which are quantitatively analyzed. The temperature dependence of relaxation times in both the monomer and polymer follows a Vogel-Fulcher behavior. The relaxation processes are identified with specific molecular motions and activation energies are calculated in a linear approximation for comparison with literature data.
Structural relaxation of Ni-Si-B amorphous ribbon

NARCIS (Netherlands)

Jurikova, A.; Csach, K.; Miskuf, J.; Ocelik, V.

The structural relaxation of the Ni-Si-B amorphous ribbon was studied by means of differential scanning calorimetry and thermomechanical analysis. It was shown that considerable length changes associated with reversible structural relaxation were revealed after a previous creep applied at higher
Relaxation training for anxiety: a ten-years systematic review with meta-analysis

OpenAIRE

Castelnuovo Gianluca; Pagnini Francesco; Manzoni Gian; Molinari Enrico

2008-01-01

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 p...
Distributed CPU multi-core implementation of SIRT with vectorized matrix kernel for micro-CT

Energy Technology Data Exchange (ETDEWEB)

Gregor, Jens [Tennessee Univ., Knoxville, TN (United States)

2011-07-01

We describe an implementation of SIRT for execution using a cluster of multi-core PCs. Algorithmic techniques are presented for reducing the size and computational cost of a reconstruction including near-optimal relaxation, scalar preconditioning, orthogonalized ordered subsets, and data-driven focus of attention. Implementation wise, a scheme is outlined which provides each core mutex-free access to its local shared memory while also balancing the workload across the cluster, and the system matrix is computed on-the-fly using vectorized code. Experimental results show the efficacy of the approach. (orig.)
Strain relaxation of germanium-tin (GeSn) fins

Science.gov (United States)

Kang, Yuye; Huang, Yi-Chiau; Lee, Kwang Hong; Bao, Shuyu; Wang, Wei; Lei, Dian; Masudy-Panah, Saeid; Dong, Yuan; Wu, Ying; Xu, Shengqiang; Tan, Chuan Seng; Gong, Xiao; Yeo, Yee-Chia

2018-02-01

Strain relaxation of biaxially strained Ge1-xSnx layer when it is patterned into Ge1-xSnx fin structures is studied. Ge1-xSnx-on-insulator (GeSnOI) substrate was realized using a direct wafer bonding (DWB) technique and Ge1-xSnx fin structures were formed by electron beam lithography (EBL) patterning and dry etching. The strain in the Ge1-xSnx fins having fin widths (WFin) ranging from 1 μm down to 80 nm was characterized using micro-Raman spectroscopy. Raman measurements show that the strain relaxation increases with decreasing WFin. Finite element (FE) simulation shows that the strain component in the transverse direction relaxes with decreasing WFin, while the strain component along the fin direction remains unchanged. For various Ge1-xSnx fin widths, transverse strain relaxation was further extracted using micro-Raman spectroscopy, which is consistent with the simulation results.
Asymptotic representation of relaxation oscillations in lasers

CERN Document Server

Grigorieva, Elena V

2017-01-01

In this book we analyze relaxation oscillations in models of lasers with nonlinear elements controlling light dynamics. The models are based on rate equations taking into account periodic modulation of parameters, optoelectronic delayed feedback, mutual coupling between lasers, intermodal interaction and other factors. With the aim to study relaxation oscillations we present the special asymptotic method of integration for ordinary differential equations and differential-difference equations. As a result, they are reduced to discrete maps. Analyzing the maps we describe analytically such nonlinear phenomena in lasers as multistability of large-amplitude relaxation cycles, bifurcations of cycles, controlled switching of regimes, phase synchronization in an ensemble of coupled systems and others. The book can be fruitful for students and technicians in nonlinear laser dynamics and in differential equations.
Cucheb: A GPU implementation of the filtered Lanczos procedure

Science.gov (United States)

Aurentz, Jared L.; Kalantzis, Vassilis; Saad, Yousef

2017-11-01

This paper describes the software package Cucheb, a GPU implementation of the filtered Lanczos procedure for the solution of large sparse symmetric eigenvalue problems. The filtered Lanczos procedure uses a carefully chosen polynomial spectral transformation to accelerate convergence of the Lanczos method when computing eigenvalues within a desired interval. This method has proven particularly effective for eigenvalue problems that arise in electronic structure calculations and density functional theory. We compare our implementation against an equivalent CPU implementation and show that using the GPU can reduce the computation time by more than a factor of 10. Program Summary Program title: Cucheb Program Files doi:http://dx.doi.org/10.17632/rjr9tzchmh.1 Licensing provisions: MIT Programming language: CUDA C/C++ Nature of problem: Electronic structure calculations require the computation of all eigenvalue-eigenvector pairs of a symmetric matrix that lie inside a user-defined real interval. Solution method: To compute all the eigenvalues within a given interval a polynomial spectral transformation is constructed that maps the desired eigenvalues of the original matrix to the exterior of the spectrum of the transformed matrix. The Lanczos method is then used to compute the desired eigenvectors of the transformed matrix, which are then used to recover the desired eigenvalues of the original matrix. The bulk of the operations are executed in parallel using a graphics processing unit (GPU). Runtime: Variable, depending on the number of eigenvalues sought and the size and sparsity of the matrix. Additional comments: Cucheb is compatible with CUDA Toolkit v7.0 or greater.
Local System Matrix Compression for Efficient Reconstruction in Magnetic Particle Imaging

Directory of Open Access Journals (Sweden)

T. Knopp

2015-01-01

Full Text Available Magnetic particle imaging (MPI is a quantitative method for determining the spatial distribution of magnetic nanoparticles, which can be used as tracers for cardiovascular imaging. For reconstructing a spatial map of the particle distribution, the system matrix describing the magnetic particle imaging equation has to be known. Due to the complex dynamic behavior of the magnetic particles, the system matrix is commonly measured in a calibration procedure. In order to speed up the reconstruction process, recently, a matrix compression technique has been proposed that makes use of a basis transformation in order to compress the MPI system matrix. By thresholding the resulting matrix and storing the remaining entries in compressed row storage format, only a fraction of the data has to be processed when reconstructing the particle distribution. In the present work, it is shown that the image quality of the algorithm can be considerably improved by using a local threshold for each matrix row instead of a global threshold for the entire system matrix.
Matrix Completion Optimization for Localization in Wireless Sensor Networks for Intelligent IoT

Directory of Open Access Journals (Sweden)

Thu L. N. Nguyen

2016-05-01

Full Text Available Localization in wireless sensor networks (WSNs is one of the primary functions of the intelligent Internet of Things (IoT that offers automatically discoverable services, while the localization accuracy is a key issue to evaluate the quality of those services. In this paper, we develop a framework to solve the Euclidean distance matrix completion problem, which is an important technical problem for distance-based localization in WSNs. The sensor network localization problem is described as a low-rank dimensional Euclidean distance completion problem with known nodes. The task is to find the sensor locations through recovery of missing entries of a squared distance matrix when the dimension of the data is small compared to the number of data points. We solve a relaxation optimization problem using a modification of Newton’s method, where the cost function depends on the squared distance matrix. The solution obtained in our scheme achieves a lower complexity and can perform better if we use it as an initial guess for an interactive local search of other higher precision localization scheme. Simulation results show the effectiveness of our approach.
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.

Anomalous relaxation and self-organization in non-equilibrium processes

OpenAIRE

Fatkullin, Ibrahim; Kladko, Konstantin; Mitkov, Igor; Bishop, A. R.

2000-01-01

We study thermal relaxation in ordered arrays of coupled nonlinear elements with external driving. We find, that our model exhibits dynamic self-organization manifested in a universal stretched-exponential form of relaxation. We identify two types of self-organization, cooperative and anti-cooperative, which lead to fast and slow relaxation, respectively. We give a qualitative explanation for the behavior of the stretched exponent in different parameter ranges. We emphasize that this is a sys...
Accelerating convergence of molecular dynamics-based structural relaxation

DEFF Research Database (Denmark)

Christensen, Asbjørn

2005-01-01

We describe strategies to accelerate the terminal stage of molecular dynamics (MD)based relaxation algorithms, where a large fraction of the computational resources are used. First, we analyze the qualitative and quantitative behavior of the QuickMin family of MD relaxation algorithms and explore...
COMPARATIVE ASSESSMENT OF NUCLEAR MAGNETIC RELAXATION CHARACTERISTICS OF SUNFLOWER AND RAPESEED LECITHIN

OpenAIRE

Lisovaya E. V.; Victorova E. P.; Agafonov O. S.; Kornen N. N.; Shahray T. A.

2015-01-01

The article presents a comparative assessment and peculiarities of nuclear magnetic relaxation characteristics of rapeseed and sunflower lecithin. It was established, that lecithin’s nuclear magnetic relaxation characteristics, namely, protons’ spin-spin relaxation time and amplitudes of nuclear magnetic relaxation signals of lecithin components, depend on content of oil’s fat acids and phospholipids, contained in the lecithin. Comparative assessment of protons’ spin-spin relaxation time of r...
F{sup 19} relaxation in non-magnetic hexafluorides; Contribution a l'etude de la relaxation des fluors dans les hexafluorures non magnetiques

Energy Technology Data Exchange (ETDEWEB)

Rigny, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-12-01

The interesting properties of the fluorine magnetic resonance in the hexafluorides of molybdenum, tungsten and uranium, are very much due to large anisotropies of the chemical shift tensors. In the solid phases these anisotropies, the values of which are deduced from line shape studies, allow one to show that the molecules undergo hindered rotations about the metal atom. The temperature and frequency dependence of the fluorine longitudinal relaxation times shows that the relaxation is due to the molecular motion. The dynamical parameters of this motion are then deduced from the complete study of the fluorine relaxation in the rotating frame. In the liquid phases, the existence of anisotropies allows an estimation of the different contributions to the relaxation. In particular, the frequency and temperature dependence of the relaxation shows it to be dominated by the spin-rotation interaction. We have shown that the strength of this interaction can be deduced from the chemical shifts, and the angle through which the molecule rotates quasi-freely can be determined. In the hexafluorides, this angle is roughly one radian at 70 C, and with the help of this value, the friction coefficients which describe the intermolecular interactions are discussed. (author) [French] Les proprietes de la resonance magnetique des fluors dans les hexafluorures de molybdene, tungstene et uranium sont influencees par l'existence de deplacements chimiques tres anisotropes. Dans les phases solides, la valeur de cette anisotropie peut etre determinee par l'analyse des formes de raies et son existence permet de montrer que les molecules sont en rotation empechee autour de leur atome central. L'etude du temps de relaxation longitudinal en fonction de la temperature et de la frequence montre que la relaxation est due aux mouvements moleculaires, aux plus hautes temperatures. Les proprietes dynamiques du mouvement sont obtenues par l'etude complete de la relaxation spin-reseau dans le referentiel
Study on properties of stress relaxation for NiTiNb shape memory alloy

International Nuclear Information System (INIS)

Zhou Xuchang; Mo Huaqiang; Zeng Guangting; Shen Baoluo; Huo Yongzhong

2002-01-01

Stress relaxation tests at high temperature are performed for NiTiNb shape memory alloy to obtain the properties of stress relaxation. The relaxation curve fitted with the expression, which is deduced based on the relation between the relaxation and the creep. With the aid of experimental data, relaxation characteristic coefficient and remaining stress ratio are obtained, which characterize the relaxation behavior. The results of the study show that stress relaxation would be more evident with the higher temperature and/or greater initial stress. NiTiNb alloy has good relaxation resistance in the temperature range 300-400 degree C and the initial stress range 260-360 MPa. NiTiNb has better properties to resist relaxation than NiTiFe, therefore it is more applicable to work at high temperature
Low temperature dielectric relaxation and charged defects in ferroelectric thin films

Directory of Open Access Journals (Sweden)

A. Artemenko

2013-04-01

Full Text Available We report a dielectric relaxation in BaTiO3-based ferroelectric thin films of different composition and with several growth modes: sputtering (with and without magnetron and sol-gel. The relaxation was observed at cryogenic temperatures (T < 100 K for frequencies from 100 Hz up to 10 MHz. This relaxation activation energy is always lower than 200 meV and is very similar to the relaxation that we reported in the parent bulk perovskites. Based on our Electron Paramagnetic Resonance (EPR investigation, we ascribe this dielectric relaxation to the hopping of electrons among Ti3+-V(O charged defects. Being dependent on the growth process and on the amount of oxygen vacancies, this relaxation can be a useful probe of defects in actual integrated capacitors with no need for specific shaping.
Green--Kubo formula for collisional relaxation

International Nuclear Information System (INIS)

Visscher, P.B.

1988-01-01

In this paper we generalize the Green--Kubo method (usually used for obtaining formulas for transport coefficients involving conserved densities) to relaxation processes occurring during collisions, such as the transfer of energy from vibrational to translational modes in a molecular fluid. We show that the relaxation rate can be calculated without evaluating time correlation functions over long times, and can in fact be written as a sum over collisions which makes the relation between the Green--Kubo method and approximate independent-collision models much clearer
InSitu SEM Investigation of Microstructural Damage Evolution and Strain Relaxation in a Melt Infiltrated SiC/SiC Composite

Science.gov (United States)

Sevener, Kathy; Chen, Zhe; Daly, Sam; Tracy, Jared; Kiser, Doug

2016-01-01

With CMC components poised to complete flight certification in turbine engines on commercial aircraft within the near future, there are many efforts within the aerospace community to model the mechanical and environmental degradation of CMCs. Direct observations of damage evolution are needed to support these modeling efforts and provide quantitative measures of damage parameters used in the various models. This study was performed to characterize the damage evolution during tensile loading of a melt infiltrated (MI) silicon carbide reinforced silicon carbide (SiC/SiC) composite. A SiC/SiC tensile coupon was loaded to a maximum global stress of 30 ksi in a tensile fixture within an SEM while observations were made at 5 ksi increments. Both traditional image analysis and DIC (digital image correlation) were used to quantify damage evolution. With the DIC analysis, microscale damage was observed at the fiber-matrix interfaces at stresses as low as 5 ksi. First matrix cracking took place between 20 and 25 ksi, accompanied by an observable relaxation in strain near matrix cracks. Matrix crack opening measurements at the maximum load ranged from 200 nm to 1.5 m. Crack opening along the fiber-matrix interface was also characterized as a function of load and angular position relative to the loading axis. This characterization was funded by NASA GRC and was performed to support NASA GRC modeling of SiC/SiC environmental degradation
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.
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.
Mechanism of resveratrol-induced relaxation of the guinea pig fundus.

Science.gov (United States)

Tsai, Ching-Chung; Tey, Shu-Leei; Lee, Ming-Che; Liu, Ching-Wen; Su, Yu-Tsun; Huang, Shih-Che

2018-04-01

Resveratrol is a polyphenolic compound that can be isolated from plants and also is a constituent of red wine. Resveratrol induces relaxation of vascular smooth muscle and may prevent cardiovascular diseases. Impaired gastric accommodation plays an important role in functional dyspepsia and fundic relaxation and is a therapeutic target of functional dyspepsia. Although drugs for fundic relaxation have been developed, these types of drugs are still rare. The purpose of this study was to investigate the relaxant effects of resveratrol in the guinea pig fundus. We studied the relaxant effects of resveratrol in the guinea pig fundus. In addition, we investigated the mechanism of resveratrol-induced relaxation on the guinea pig fundus by using tetraethylammonium (a non-selective potassium channel blocker), apamine (a selective inhibitor of the small conductance calcium-activated potassium channel), iberiotoxin (an inhibitor of large conductance calcium-activated potassium channels), glibenclamide (an ATP-sensitive potassium channel blocker), KT 5720 (a cAMP-dependent protein kinase A inhibitor), KT 5823 (a cGMP-dependent protein kinase G inhibitor), NG-nitro-L-arginine (a competitive inhibitor of nitric oxide synthase), tetrodotoxin (a selective neuronal Na + channel blocker), ω-conotoxin GVIA (a selective neuronal Ca 2+ channel blocker) and G-15 (a G-protein coupled estrogen receptor antagonist). The results of this study showed that resveratrol has potent and dose-dependent relaxant effects on the guinea pig fundic muscle. In addition, the results showed that resveratrol-induced relaxation of the guinea pig fundus occurs through nitric oxide and ATP-sensitive potassium channels. This study provides the first evidence concerning the relaxant effects of resveratrol in the guinea pig fundic muscle strips. Furthermore, resveratrol may be a potential drug to relieve gastrointestinal dyspepsia. Copyright © 2018 Elsevier GmbH. All rights reserved.
Robust estimation of the correlation matrix of longitudinal data

KAUST Repository

Maadooliat, Mehdi

2011-09-23

We propose a double-robust procedure for modeling the correlation matrix of a longitudinal dataset. It is based on an alternative Cholesky decomposition of the form Σ=DLL⊤D where D is a diagonal matrix proportional to the square roots of the diagonal entries of Σ and L is a unit lower-triangular matrix determining solely the correlation matrix. The first robustness is with respect to model misspecification for the innovation variances in D, and the second is robustness to outliers in the data. The latter is handled using heavy-tailed multivariate t-distributions with unknown degrees of freedom. We develop a Fisher scoring algorithm for computing the maximum likelihood estimator of the parameters when the nonredundant and unconstrained entries of (L,D) are modeled parsimoniously using covariates. We compare our results with those based on the modified Cholesky decomposition of the form LD2L⊤ using simulations and a real dataset. © 2011 Springer Science+Business Media, LLC.
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.
Interrelation of creep and relaxation: a modeling approach for ligaments.

Science.gov (United States)

Lakes, R S; Vanderby, R

1999-12-01

Experimental data (Thornton et al., 1997) show that relaxation proceeds more rapidly (a greater slope on a log-log scale) than creep in ligament, a fact not explained by linear viscoelasticity. An interrelation between creep and relaxation is therefore developed for ligaments based on a single-integral nonlinear superposition model. This interrelation differs from the convolution relation obtained by Laplace transforms for linear materials. We demonstrate via continuum concepts of nonlinear viscoelasticity that such a difference in rate between creep and relaxation phenomenologically occurs when the nonlinearity is of a strain-stiffening type, i.e., the stress-strain curve is concave up as observed in ligament. We also show that it is inconsistent to assume a Fung-type constitutive law (Fung, 1972) for both creep and relaxation. Using the published data of Thornton et al. (1997), the nonlinear interrelation developed herein predicts creep behavior from relaxation data well (R > or = 0.998). Although data are limited and the causal mechanisms associated with viscoelastic tissue behavior are complex, continuum concepts demonstrated here appear capable of interrelating creep and relaxation with fidelity.
The time-dependent density matrix renormalisation group method

Science.gov (United States)

Ma, Haibo; Luo, Zhen; Yao, Yao

2018-04-01

Substantial progress of the time-dependent density matrix renormalisation group (t-DMRG) method in the recent 15 years is reviewed in this paper. By integrating the time evolution with the sweep procedures in density matrix renormalisation group (DMRG), t-DMRG provides an efficient tool for real-time simulations of the quantum dynamics for one-dimensional (1D) or quasi-1D strongly correlated systems with a large number of degrees of freedom. In the illustrative applications, the t-DMRG approach is applied to investigate the nonadiabatic processes in realistic chemical systems, including exciton dissociation and triplet fission in polymers and molecular aggregates as well as internal conversion in pyrazine molecule.
Strain redistribution around holes and notches in fiber-reinforced cross-woven brittle matrix composites

DEFF Research Database (Denmark)

Jacobsen, Torben Krogsdal; Brøndsted, Povl

1997-01-01

Mechanics, and an identification procedure based on a uni-axial tensile test and a shear test the strain redistribution around a hole or a notch due to matrix cracking can be predicted. Damage due to fiber breakage is not included in the model. Initial matrix damage in the C-f/SiCm material has...
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.
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.
Matrix Intensification Affects Body and Physiological Condition of Tropical Forest-Dependent Passerines.

Directory of Open Access Journals (Sweden)

Justus P Deikumah

Full Text Available Matrix land-use intensification is a relatively recent and novel landscape change that can have important influences on the biota within adjacent habitat patches. While there are immediate local changes that it brings about, the influences on individual animals occupying adjacent habitats may be less evident initially. High-intensity land use could induce chronic stress in individuals in nearby remnants, leading ultimately to population declines. We investigated how physiological indicators and body condition measures of tropical forest-dependent birds differ between forest adjacent to surface mining sites and that near farmlands at two distances from remnant edge in southwest Ghana. We used mixed effects models of several condition indices including residual body mass and heterophil to lymphocyte (H/L ratios (an indicator of elevated chronic stress to explore the effect of matrix intensity on forest-dependent passerines classed as either sedentary area-sensitive habitat specialists or nomadic generalists. Individual birds occupying tropical forest remnants near surface mining sites were in poorer condition, as indicated by lower residual body mass and elevated chronic stress, compared to those in remnants near agricultural lands. The condition of the sedentary forest habitat specialists white-tailed alethe, Alethe diademata and western olive sunbird, Cyanomitra obscura was most negatively affected by high-intensity surface mining land-use adjacent to remnants, whereas generalist species were not affected. Land use intensification may set in train a new trajectory of faunal relaxation beyond that expected based on habitat loss alone. Patterns of individual condition may be useful in identifying habitats where species population declines may occur before faunal relaxation has concluded.
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

Dielectric Relaxation Studies of Alkyl Methacrylate–Phenol Mixtures ...

African Journals Online (AJOL)

The Kirkwood correlation factor and the excess inverse relaxation time were determined and they yield information on the molecular interactions occurring in the systems. The values of the static permittivity and the relaxation time increase with an increase in the percentage of phenol in the mixtures. KEYWORDS: Dielectric ...
Plasma relaxation of cold electrons and hot ions

International Nuclear Information System (INIS)

Potapenko, I.F.; Sakanaka, P.H.

1996-01-01

The relaxation process of a space uniform plasma composed of cold electrons and one species of hot ions studied numerically. Special attention has been paid to the deviation of relaxation from the classical picture which is characterized by a weakly non-isothermic situation. (author). 6 refs., 2 figs
Suppression of Raman electron spin relaxation of radicals in crystals. Comparison of Cu2+ and free radical relaxation in triglycine sulfate and Tutton salt single crystals.

Science.gov (United States)

Hoffmann, S K; Goslar, J; Lijewski, S

2011-08-31

Electron spin-lattice relaxation was measured by the electron spin echo method in a broad temperature range above 4.2 K for Cu(2+) ions and free radicals produced by ionizing radiation in triglycine sulfate (TGS) and Tutton salt (NH4)(2)Zn(SO4)2 ⋅ 6H2O crystals. Localization of the paramagnetic centres in the crystal unit cells was determined from continuous wave electron paramagnetic resonance spectra. Various spin relaxation processes and mechanisms are outlined. Cu(2+) ions relax fast via two-phonon Raman processes in both crystals involving the whole phonon spectrum of the host lattice. This relaxation is slightly slower for TGS where Cu(2+) ions are in the interstitial position. The ordinary Raman processes do not contribute to the radical relaxation which relaxes via the local phonon mode. The local mode lies within the acoustic phonon band for radicals in TGS but within the optical phonon range in (NH4)(2)Zn(SO4)2 ⋅ 6H2O. In the latter the cross-relaxation was considered. A lack of phonons around the radical molecules suggested a local crystal amorphisation produced by x- or γ-rays.
Relaxed plasmas in external magnetic fields

International Nuclear Information System (INIS)

Spies, G.O.; Li, J.

1991-08-01

The well-known theory of relaxed plasmas (Taylor states) is extended to external magnetic fields whose field lines intersect the conducting toroidal boundary. Application to an axially symmetric, large-aspect-ratio torus with circular cross section shows that the maximum pinch ratio, and hence the phenomenon of current saturation, is independent of the external field. The relaxed state is explicitly given for an external octupole field. In this case, field reversal is inhibited near parts of the boundary if the octupole generates magnetic x-points within the plasma. (orig.)
Stress relaxing hyaluronic acid-collagen hydrogels promote cell spreading, fiber remodeling, and focal adhesion formation in 3D cell culture.

Science.gov (United States)

Lou, Junzhe; Stowers, Ryan; Nam, Sungmin; Xia, Yan; Chaudhuri, Ovijit

2018-02-01

The physical and architectural cues of the extracellular matrix (ECM) play a critical role in regulating important cellular functions such as spreading, migration, proliferation, and differentiation. Natural ECM is a complex viscoelastic scaffold composed of various distinct components that are often organized into a fibrillar microstructure. Hydrogels are frequently used as synthetic ECMs for 3D cell culture, but are typically elastic, due to covalent crosslinking, and non-fibrillar. Recent work has revealed the importance of stress relaxation in viscoelastic hydrogels in regulating biological processes such as spreading and differentiation, but these studies all utilize synthetic ECM hydrogels that are non-fibrillar. Key mechanotransduction events, such as focal adhesion formation, have only been observed in fibrillar networks in 3D culture to date. Here we present an interpenetrating network (IPN) hydrogel system based on HA crosslinked with dynamic covalent bonds and collagen I that captures the viscoelasticity and fibrillarity of ECM in tissues. The IPN hydrogels exhibit two distinct processes in stress relaxation, one from collagen and the other from HA crosslinking dynamics. Stress relaxation in the IPN hydrogels can be tuned by modulating HA crosslinker affinity, molecular weight of the HA, or HA concentration. Faster relaxation in the IPN hydrogels promotes cell spreading, fiber remodeling, and focal adhesion (FA) formation - behaviors often inhibited in other hydrogel-based materials in 3D culture. This study presents a new, broadly adaptable materials platform for mimicking key ECM features of viscoelasticity and fibrillarity in hydrogels for 3D cell culture and sheds light on how these mechanical and structural cues regulate cell behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.
Ultrafine Ceramic Grains Embedded in Metallic Glass Matrix: Achieving Superior Wear Resistance via Increase in Both Hardness and Toughness.

Science.gov (United States)

Yang, Lina; Wen, Mao; Dai, Xuan; Cheng, Gang; Zhang, Kan

2018-05-09

As structural materials, crystalline or metallic glass materials have attracted scientific and practical interests. However, some mechanisms involving critical size and shear bands have adverse effects on their mechanical properties. Here, we counter these two effects by introducing a special structure with ultrafine ceramic grains (with a diameter of ∼2.0 nm) embedded into a metallic glass matrix, wherein the grains are mainly composed of a Ta-W-N solid solution structure in nature, surrounded by a W-based amorphous matrix that contains Ta and N atoms. Such a structure is in situ formed during preparation, which combines the merits of both phases to achieve simultaneous increase in hardness and toughness relative to references (pure TaN and W) and thus superior wear resistance. Even more remarkable, a favorable variation of increased hardness but reduced elasticity modulus can be induced by this structure. Intrinsically, ultrafine ceramic grains (free of dislocations), embedded in the metallic glass matrix, could prevent shear band propagation within the glass matrix and further improve the hardness of the matrix material. In return, such glass matrix allows for stiffness neutralization and structural relaxation to reduce the elasticity modulus of ceramic grains. This study will offer a new guidance to fabricate ultrahigh-performance metal-based composites.
A generalization of random matrix theory and its application to statistical physics.

Science.gov (United States)

Wang, Duan; Zhang, Xin; Horvatic, Davor; Podobnik, Boris; Eugene Stanley, H

2017-02-01

To study the statistical structure of crosscorrelations in empirical data, we generalize random matrix theory and propose a new method of cross-correlation analysis, known as autoregressive random matrix theory (ARRMT). ARRMT takes into account the influence of auto-correlations in the study of cross-correlations in multiple time series. We first analytically and numerically determine how auto-correlations affect the eigenvalue distribution of the correlation matrix. Then we introduce ARRMT with a detailed procedure of how to implement the method. Finally, we illustrate the method using two examples taken from inflation rates for air pressure data for 95 US cities.
Characterization of structural relaxation in inorganic glasses using length dilatometry

Science.gov (United States)

Koontz, Erick

The processes that govern how a glass relaxes towards its thermodynamic quasi-equilibrium state are major factors in understanding glass behavior near the glass transition region, as characterized by the glass transition temperature (Tg). Intrinsic glass properties such as specific volume, enthalpy, entropy, density, etc. are used to map the behavior of the glass network below in and near the transition region. The question of whether a true thermodynamic second order phase transition takes place in the glass transition region is another pending question. Linking viscosity behavior to entropy, or viewing the glass configuration as an energy landscape are just a couple of the most prevalent methods used for attempting to understand the glass transition. The structural relaxation behavior of inorganic glasses is important for more than scientific reasons, many commercial glass processing operations including glass melting and certain forms of optical fabrication include significant time spent in the glass transition region. For this reason knowledge of structural relaxation processes can, at a minimum, provide information for annealing duration of melt-quenched glasses. The development of a predictive model for annealing time prescription has the potential to save glass manufacturers significant time and money as well as increasing volume throughput. In optical hot forming processes such as precision glass molding, molded optical components can significantly change in shape upon cooling through the glass transition. This change in shape is not scientifically predictable as of yet though manufacturers typically use empirical rules developed in house. The classification of glass behavior in the glass transition region would allow molds to be accurately designed and save money for the producers. The work discussed in this dissertation is comprised of the development of a dilatometric measurement and characterization method of structural relaxation. The measurement and
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
Stress relaxation characteristics of type 304 stainless steel

International Nuclear Information System (INIS)

Manjoine, M.J.

1975-01-01

The stress relaxation of type 304 stainless steel below 900 0 F (482 0 C) is practically time independent after 100 h and has a maximum of about 18 per cent. The per cent relaxation decreases with increasing degree of cold work and with decreasing stress. Above 900 0 F the per cent relaxation increases with time, temperature, and cold work. The initial stress can also be increased for cold work materials so that the remaining stress can be maintained at a higher value even up to 1200 0 F (649 0 C). Time-temperature parameters are practical to correlate and extrapolate the data in the higher temperature range. (author)
Matrix completion by deep matrix factorization.

Science.gov (United States)

Fan, Jicong; Cheng, Jieyu

2018-02-01

Conventional methods of matrix completion are linear methods that are not effective in handling data of nonlinear structures. Recently a few researchers attempted to incorporate nonlinear techniques into matrix completion but there still exists considerable limitations. In this paper, a novel method called deep matrix factorization (DMF) is proposed for nonlinear matrix completion. Different from conventional matrix completion methods that are based on linear latent variable models, DMF is on the basis of a nonlinear latent variable model. DMF is formulated as a deep-structure neural network, in which the inputs are the low-dimensional unknown latent variables and the outputs are the partially observed variables. In DMF, the inputs and the parameters of the multilayer neural network are simultaneously optimized to minimize the reconstruction errors for the observed entries. Then the missing entries can be readily recovered by propagating the latent variables to the output layer. DMF is compared with state-of-the-art methods of linear and nonlinear matrix completion in the tasks of toy matrix completion, image inpainting and collaborative filtering. The experimental results verify that DMF is able to provide higher matrix completion accuracy than existing methods do and DMF is applicable to large matrices. Copyright © 2017 Elsevier Ltd. All rights reserved.
Models for multiple relaxation processes in collagen fiber

Indian Academy of Sciences (India)

... originate from stress strain induced changes in hydrogen bond network whereas the other seems to be more strongly coupled to salt like bridges and electrostatic interactions. Urea alters the activation energy for one relaxation step while pH and solvent dielectric constant alter the relaxation behavior one set of processes.
On the relaxation of cold electrons and hot ions

International Nuclear Information System (INIS)

Potapenko, I.F.; Bobylev, A.V.; Azevedo, C.A. de; Sakanaka, P.H.; Assis, A.S. de

1998-01-01

The relaxation process of a space uniform plasma composed of cold electrons and one species of hot ions is studied numerically using one- and two-dimensional Landau - Fokker - Planck codes. Relaxation of a monoenergetic ion beam is considered in possibly extreme temperature regimes. Special attention is paid to the deviation of the relaxation process from the classical picture, which is characterized by the close initial temperatures T e >(m e /m i ) 1/3 T i . The present results give quite a clear idea of the relaxation picture for any initial temperatures also in extreme temperature regimes. A difference scheme, preserving the number of particles and the energy, gives the possibility of solving the problem numerically without error accumulation, except for machine errors. copyright 1998 American Institute of Physics
¹²⁹ Xe NMR Relaxation-Based Macromolecular Sensing

Energy Technology Data Exchange (ETDEWEB)

Gomes, Muller D. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Dao, Phuong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Jeong, Keunhong [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Slack, Clancy C. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Vassiliou, Christophoros C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Finbloom, Joel A. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Francis, Matthew B. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Wemmer, David E. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Physical Biosciences Division; Pines, Alexander [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials Sciences Division; Univ. of California, Berkeley, CA (United States). Dept. of Chemistry

2016-07-29

A ¹²⁹Xe NMR relaxation-based sensing approach is reported on that exploits changes in the bulk xenon relaxation rate induced by slowed tumbling of a cryptophane-based sensor upon target binding. The amplification afforded by detection of the bulk dissolved xenon allows sensitive detection of targets. The sensor comprises a xenon-binding cryptophane cage, a target interaction element, and a metal chelating agent. Xenon associated with the target-bound cryptophane cage is rapidly relaxed and then detected after exchange with the bulk. Here we show that large macromolecular targets increase the rotational correlation time of xenon, increasing its relaxation rate. Upon binding of a biotin-containing sensor to avidin at 1.5 μM concentration, the free xenon T₂ is reduced by a factor of 4.
The covariance matrix of derived quantities and their combination

International Nuclear Information System (INIS)

Zhao, Z.; Perey, F.G.

1992-06-01

The covariance matrix of quantities derived from measured data via nonlinear relations are only approximate since they are functions of the measured data taken as estimates for the true values of the measured quantities. The evaluation of such derived quantities entails new estimates for the true values of the measured quantities and consequently implies a modification of the covariance matrix of the derived quantities that was used in the evaluation process. Failure to recognize such an implication can lead to inconsistencies between the results of different evaluation strategies. In this report we show that an iterative procedure can eliminate such inconsistencies
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
Direct integration of the S-matrix applied to rigorous diffraction

International Nuclear Information System (INIS)

Iff, W; Lindlein, N; Tishchenko, A V

2014-01-01

A novel Fourier method for rigorous diffraction computation at periodic structures is presented. The procedure is based on a differential equation for the S-matrix, which allows direct integration of the S-matrix blocks. This results in a new method in Fourier space, which can be considered as a numerically stable and well-parallelizable alternative to the conventional differential method based on T-matrix integration and subsequent conversions from the T-matrices to S-matrix blocks. Integration of the novel differential equation in implicit manner is expounded. The applicability of the new method is shown on the basis of 1D periodic structures. It is clear however, that the new technique can also be applied to arbitrary 2D periodic or periodized structures. The complexity of the new method is O(N 3 ) similar to the conventional differential method with N being the number of diffraction orders. (fast track communication)
Relaxed Binaural LCMV Beamforming

NARCIS (Netherlands)

Koutrouvelis, A.; Hendriks, R.C.; Heusdens, R.; Jensen, Jesper Rindom

2017-01-01

In this paper, we propose a new binaural beamforming technique, which can be seen as a relaxation of the linearly constrained minimum variance (LCMV) framework. The proposed method can achieve simultaneous noise reduction and exact binaural cue preservation of the target source, similar to the
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
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.

Direct determination of scattering time delays using the R-matrix propagation method

International Nuclear Information System (INIS)

Walker, R.B.; Hayes, E.F.

1989-01-01

A direct method for determining time delays for scattering processes is developed using the R-matrix propagation method. The procedure involves the simultaneous generation of the global R matrix and its energy derivative. The necessary expressions to obtain the energy derivative of the S matrix are relatively simple and involve many of the same matrix elements required for the R-matrix propagation method. This method is applied to a simple model for a chemical reaction that displays sharp resonance features. The test results of the direct method are shown to be in excellent agreement with the traditional numerical differentiation method for scattering energies near the resonance energy. However, for sharp resonances the numerical differentiation method requires calculation of the S-matrix elements at many closely spaced energies. Since the direct method presented here involves calculations at only a single energy, one is able to generate accurate energy derivatives and time delays much more efficiently and reliably
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.
Evaluation of long-term relaxation for high-strength bolted connections

International Nuclear Information System (INIS)

Nah, H. S.; Lee, H. J.; Kim, K. S.

2010-01-01

It is general that the clamping forces of high-strength bolts diminish within a certain time period after the initial clamping force. In case that special treatments are applied on a faying surface, the clamping force is relaxed severely. Tests were conducted for slip critical joints subjected to various faying surface parameters. The candidates for bolt were two kinds: Korean Standard and American Standard. Relaxation occurred for slip resistant joints with an uncoated surface that had been shot-blasted, cleaned, milled or rusted. In case of ASTM hexagon bolts, the initial clamping force dropped from 7.9% to 13.6% after 1, 000 hours while relaxation ratio was the range from 8.7% to 15.4% for KS bolts. For ASTM hexagon bolt joints with a 5 mil thick zinc coating, the clamping force of the bolts decreased 15.0%, while relaxation ratio was 12.85% for KS bolts. For 4.9 mil thick red lead painted treatment, the relaxation ratio was 18.7% for ASTM hexagon bolt, 34.9% for KS bolts. Regardless of faying surface treatments, the first week charged at least 86% of total relaxation from this test. (authors)
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.
Integrable Floquet dynamics, generalized exclusion processes and "fused" matrix ansatz

Science.gov (United States)

Vanicat, Matthieu

2018-04-01

We present a general method for constructing integrable stochastic processes, with two-step discrete time Floquet dynamics, from the transfer matrix formalism. The models can be interpreted as a discrete time parallel update. The method can be applied for both periodic and open boundary conditions. We also show how the stationary distribution can be built as a matrix product state. As an illustration we construct parallel discrete time dynamics associated with the R-matrix of the SSEP and of the ASEP, and provide the associated stationary distributions in a matrix product form. We use this general framework to introduce new integrable generalized exclusion processes, where a fixed number of particles is allowed on each lattice site in opposition to the (single particle) exclusion process models. They are constructed using the fusion procedure of R-matrices (and K-matrices for open boundary conditions) for the SSEP and ASEP. We develop a new method, that we named "fused" matrix ansatz, to build explicitly the stationary distribution in a matrix product form. We use this algebraic structure to compute physical observables such as the correlation functions and the mean particle current.
ℋ-matrix techniques for approximating large covariance matrices and estimating its parameters

KAUST Repository

Litvinenko, Alexander; Genton, Marc G.; Sun, Ying; Keyes, David E.

2016-01-01

In this work the task is to use the available measurements to estimate unknown hyper-parameters (variance, smoothness parameter and covariance length) of the covariance function. We do it by maximizing the joint log-likelihood function. This is a non-convex and non-linear problem. To overcome cubic complexity in linear algebra, we approximate the discretised covariance function in the hierarchical (ℋ-) matrix format. The ℋ-matrix format has a log-linear computational cost and storage O(knlogn), where rank k is a small integer. On each iteration step of the optimization procedure the covariance matrix itself, its determinant and its Cholesky decomposition are recomputed within ℋ-matrix format. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
ℋ-matrix techniques for approximating large covariance matrices and estimating its parameters

KAUST Repository

Litvinenko, Alexander

2016-10-25

In this work the task is to use the available measurements to estimate unknown hyper-parameters (variance, smoothness parameter and covariance length) of the covariance function. We do it by maximizing the joint log-likelihood function. This is a non-convex and non-linear problem. To overcome cubic complexity in linear algebra, we approximate the discretised covariance function in the hierarchical (ℋ-) matrix format. The ℋ-matrix format has a log-linear computational cost and storage O(knlogn), where rank k is a small integer. On each iteration step of the optimization procedure the covariance matrix itself, its determinant and its Cholesky decomposition are recomputed within ℋ-matrix format. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)
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.
Relaxation of quadrupole orientation in an optically pumped alkali vapour

Energy Technology Data Exchange (ETDEWEB)

Bernabeu, E; Tornos, J

1985-04-01

The relaxation of quadrupole orientation (alignment) in an optically pumped alkali vapour is theoretically studied by taking into account the relaxation processes by alkali-buffer gas, alkali-alkali with spin exchange and alkali-cell wall (diffusion process) collisions. The relaxation transients of the quadrupole orientation are obtained by introducing a first-order weak-pumping approximation (intermediate pumping) less restrictive than the usually considered (zeroth order) one.
Dielectric relaxation phenomena of rigid polar liquid molecules ...

Indian Academy of Sciences (India)

The probability of showing double relaxation is ... liquids can, however, be inferred from the measured relaxation time τ by Cole–Cole [3], ... A graphical method [13] was, soon employed from Fr¨ohlich's distribution function [14] to ...... tive to choose a few data for some systems for which chi-square values were adjusted to.
A COMPARATIVE STUDY ON EFFECTIVENESS OF STATIC STRETCH AND HOLD RELAX TECHNIQUES OVER HAMSTRING FLEXIBILITY

Directory of Open Access Journals (Sweden)

N. Vamsidhar

2014-12-01

Full Text Available Background: Flexibility is important in prevention of injury, muscular and postural imbalance more over the Hamstring flexibility has a lion share in sports performances and preventing DOMS. Stretching procedures increases the ROM by embarking on biomechanics and Neurologic and molecular mechanics. Hamstrings, the two joint muscle plays a crucial role in two joints integrity and also spine as they are in closed kinematic chain. The hamstring muscles represent the primary flexors of Knee. Hamstrings tightness results in Limits Knee extension when hip is flexed, Posterior Pelvic tilt, and flatten the lumbar spine. Methods: The subjects selected randomly and divided into two groups (Experimental group and control group.30 samples in One group applied with Static Stretch once a day for 3 repetitions 5 days a week for six weeks and 30 samples in other group applied with Hold relax technique once a day for 4 repetitions 5 days a week for six weeks. The knee joint range of motion was measured at the end of every week with Universal goniometer. Results: By comparing the means of Group – I, given Static Stretch and Group – II, given Hold relax Technique for six weeks implied that there is improvement of flexibility in Group – II and the ‘P’ value < 0.01 shows the difference is highly significant. Conclusion: This study concludes that the hold relax Technique method has proved to be better technique then the static stretch for improving hamstring flexibility.
Biexciton relaxation associated with dissociation into a surface polariton pair in semiconductor films

Science.gov (United States)

Mitsumori, Yasuyoshi; Matsuura, Shimpei; Uchiyama, Shoichi; Saito, Kentarao; Edamatsu, Keiichi; Nakayama, Masaaki; Ajiki, Hiroshi

2018-04-01

We study the biexciton relaxation process in CuCl films ranging from 6 to 200 nm. The relaxation time is measured as the dephasing time and the lifetime. We observe a unique thickness dependence of the biexciton relaxation time and also obtain an ultrafast relaxation time with a timescale as short as 100 fs, while the exciton lifetime monotonically decreases with increasing thickness. By analyzing the exciton-photon coupling energy for a surface polariton, we theoretically calculate the biexciton relaxation time as a function of the thickness. The calculated dependence qualitatively reproduces the observed relaxation time, indicating that the biexciton dissociation into a surface polariton pair is one of the major biexciton relaxation processes.
Theory of vibrational relaxation in mixtures of ortho- and para-hydrogen

International Nuclear Information System (INIS)

Moise, A.; Pritchard, H.O.

1981-01-01

A numerical study of the vibrational relaxation at 500 K of a mixture of ortho-H 2 and para-H 2 is described. The required state-to-state rate constants were calculated and missing pieces of data were estimated by interpolation. It is concluded that only one relaxation time will be observed in any mixture of orth-H 2 and para-H 2 and that (except at very high dilutions in a third inert gas) the relaxation rate constant will be close to the mean of the individual rate constants for relaxation, weighted according to the respective mole fractions of ortho-H 2 and para-H 2 present in the mixture. The relaxation process can be modelled as an electrical RC network, whose time constants can be written down as sums of the appropriate microscopic rate constants. By using this model the conditions required for a mixture of two gases to exhibit two distinct vibrational relaxation times can be explored
Multi-Phonon Relaxation of H^- Local Modes in CaF_2

Science.gov (United States)

Davison, C. P.; Happek, U.; Campbell, J. A.; Engholm, J. R.; Schwettman, H. A.

1998-03-01

Local modes play an important role in the relaxation of vibrational modes of small molecules in solids (J.R. Engholm, C.W. Rella, H.A. Schwettman, and U. Happek; Phys. Rev. Lett. 77), 1302 (1996)., but only few attempts have been reported to study the relaxation of these local modes. Here we report on experiments to investigate the non-radiative relaxation of H^- local modes in CaF_2. Using a pump-probe technique, saturation experiments on the H^- local modes, both interstitial and substitutional, were performed at the Stanford Free Electron Laser Center. At low temperature we find a relaxation time T1 of 45 psec for the substitutional H^- local mode, and a more rapid relaxation for the interstitial H^- local modes next to La^3+ and Lu^3+ impurities. Information on the decay channels of the local modes are obtained from the characteristic temperature dependence of the relaxation rates. This work is supported in part by the ONR, Grant No. N00014-94-1024.
Interactions between tungsten carbide (WC) particulates and metal matrix in WC-reinforced composites

International Nuclear Information System (INIS)

Lou, D.; Hellman, J.; Luhulima, D.; Liimatainen, J.; Lindroos, V.K.

2003-01-01

A variety of experimental techniques have been used to investigate the interactions between tungsten carbide (WC-Co 88/12) particulates and the matrix in some new wear resistant cobalt-based superalloy and steel matrix composites produced by hot isostatic pressing. The results show that the chemical composition of the matrix has a strong influence on the interface reaction between WC and matrix and the structural stability of the WC particulates in the composite. Some characteristics of the interaction between matrix and reinforcement are explained by the calculation of diffusion kinetics. The three-body abrasion wear resistance of the composites has been examined based on the ASTM G65-91 standard procedure. The wear behavior of the best composites of this study shows great potential for wear protection applications
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.
Electron spin-lattice relaxation mechanisms of radiation produced trapped electrons and hydrogen atoms in aqueous and organic glassy matrices. Modulation of electron nuclear dipolar interaction by tunnelling modes in a glassy matrix. [. gamma. rays

Energy Technology Data Exchange (ETDEWEB)

Bowman, M K; Kevan, L [Wayne State Univ., Detroit, Mich. (USA). Dept. of Chemistry

1977-01-01

The spin lattice relaxation of trapped electrons in aqueous and organic glasses and trapped hydrogen atoms in phosphoric acid glass has been directly studied as a function of temperature by the saturation recovery method. Below 50 to 100 K, the major spin lattice relaxation mechanism involves modulation of the electron nuclear dipolar (END) interaction with nuclei in the radical's environment by tunnelling of those nuclei between two or more positions. This relaxation mechanism occurs with high efficiency and has a characteristic linear temperature dependence. The tunnelling nuclei around trapped electrons do not seem to involve the nearest neighbor nuclei which are oriented by the electron in the process of solvation. Instead the tunnelling nuclei typically appear to be next nearest neighbors to the trapped electron. The identities of the tunnelling nuclei have been deduced by isotopic substitution and are attributed to: Na in 10 mol dm/sup -3/ NaOH aqueous glass, ethyl protons in ethanol glass, methyl protons in methanol glass and methyl protons in MTHF glass. For trapped hydrogen atoms in phosphoric acid, the phosphorus nuclei appear to be the effective tunnelling nuclei. Below approximately 10 K the spin lattice relaxation is dominated by a temperature independent cross relaxation term for H atoms in phosphoric acid glass and for electrons in 10 mol dm/sup -3/ NaOH aqueous glass, but not for electrons in organic glasses. This is compared with recent electron-electron double resonance studies of cross relaxation in these glasses. The spin lattice relaxation of O/sup -/ formed in 10 mol dm/sup -3/ NaOH aqueous glass was also studied and found to be mainly dominated by a Raman process with an effective Debye temperature of about 100 K.
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 ...
Exploiting Sparsity in SDP Relaxation for Sensor Network Localization

NARCIS (Netherlands)

S. Kim (Sunyoung); M. Kojima; H. Waki (Hayato)

2008-01-01

htmlabstract A sensor network localization problem can be formulated as a quadratic optimization problem (QOP). For quadratic optimization problems, semidefinite programming (SDP) relaxation by Lasserre with relaxation order 1 for general polynomial optimization problems (POPs) is known to be
Exploiting Sparsity in SDP Relaxation for Sensor Network Localization

NARCIS (Netherlands)

S. Kim (Sunyoung); M. Kojima; H. Waki (Hayato)

2009-01-01

htmlabstract A sensor network localization problem can be formulated as a quadratic optimization problem (QOP). For quadratic optimization problems, semidefinite programming (SDP) relaxation by Lasserre with relaxation order 1 for general polynomial optimization problems (POPs) is known to be

Exciton-relaxation dynamics in lead halides

International Nuclear Information System (INIS)

Iwanaga, Masanobu; Hayashi, Tetsusuke

2003-01-01

We survey recent comprehensive studies of exciton relaxation in the crystals of lead halides. The luminescence and electron-spin-resonance studies have revealed that excitons in lead bromide spontaneously dissociate and both electrons and holes get self-trapped individually. Similar relaxation has been also clarified in lead chloride. The electron-hole separation is ascribed to repulsive correlation via acoustic phonons. Besides, on the basis of the temperature profiles of self-trapped states, we discuss the origin of luminescence components which are mainly induced under one-photon excitation into the exciton band in lead fluoride, lead chloride, and lead bromide
Radiative and nonradiative lifetimes in excited states of Ar, Kr and Xe atoms in Ne matrix

International Nuclear Information System (INIS)

Hahn, U.; Schwentner, N.

1979-10-01

Synchrotron radiation with its intense continuum and its excellent time structure has been exploited for time resolved luminescence spectroscopy in the solid state. By selective excitation of n = 1, n' = 1 and n = 2 exciton states of Xe, Kr and Ar atoms in Ne matrix we were able to identify the emitting states involved. Lifetimes within the cascade of radiative and radiationless relaxation between excited states as well as the radiative lifetimes for transitions to the ground state have been derived from the decay curves. Energy positions and radiative lifetimes of the emitting states correspond quite well with those of the free atoms. Radiative and radiationless relaxation processes take place within the manifold of excited states of the guest atoms. The rate constants for radiationless decay confirm an energy gap law. The order of the radiationless processes reaches in some cases extremely high values. Selection rules for spin and angular momentum are essential to understand the observed radiationless transition rates. (orig.)
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
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.
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.
Relaxation and hypnosis in pediatric dental patients.

Science.gov (United States)

Peretz, B

1996-01-01

Relaxation and hypnosis are methods which, may solve the problem of extreme dental anxiety, when all other methods, behavioral or pharmacological may not be used. A simple definition of hypnosis is suggestion and repetition. Suggestion is the process whereby an individual accepts a proposition put to him by another, without having the slightest logical reason for doing so. Relaxation is one method of inducing hypnosis. A case of using hypnosis on an 11-year-old boy is described.
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 of Thick-Walled Cylinders and Spheres

DEFF Research Database (Denmark)

Saabye Ottosen, N.

1982-01-01

Using the nonlinear creep law proposed by Soderberg, (1936) closed-form solutions are derived for the relaxation of incompressible thick-walled spheres and cylinders in plane strain. These solutions involve series expressions which, however, converge very quickly. By simply ignoring these series...... expressions, extremely simple approximate solutions are obtained. Despite their simplicity these approximations possess an accuracy that is superior to approximations currently in use. Finally, several physical aspects related to the relaxation of cylinders and spheres are discussed...
Thermal Dynamics of Xanthene Dye in Polymer Matrix Excited by Double Pulse Laser Radiation

Science.gov (United States)

Samusev, Ilia; Borkunov, Rodion; Tsarkov, Maksim; Konstantinova, Elizaveta; Antipov, Yury; Demin, Maksim; Bryukhanov, Valery

2018-01-01

Double-pulse laser excitation of the eosin and silver nanoparticles embedded into polymer media is known to be a method of electronic-vibrational energy deactivation kinetic process information obtaining and polymer thermal dynamics investigation. We have studied the vibrational relaxation processes in dye molecules (eosin) and nanoparticles in polyvinyl alcohol after two time-shifted laser pulses with fast and delayed fluorescence kinetics study. In order to simulate thermal and photophysical processes caused by double photon excitation, we solved heat transfer and energy deactivation differential equations numerically. The simulation allowed us to obtain the value of heat conductivity coefficient of polymer matrix.
Relaxation oscillation logic in Josephson junction circuits

International Nuclear Information System (INIS)

Fulton, T.A.

1981-01-01

A dc powered, self-resetting Josephson junction logic circuit relying on relaxation oscillations is described. A pair of Josephson junction gates are connected in series, a first shunt is connected in parallel with one of the gates, and a second shunt is connected in parallel with the series combination of gates. The resistance of the shunts and the dc bias current bias the gates so that they are capable of undergoing relaxation oscillations. The first shunt forms an output line whereas the second shunt forms a control loop. The bias current is applied to the gates so that, in the quiescent state, the gate in parallel with the second shunt is at V O, and the other gate is undergoing relaxation oscillations. By controlling the state of the first gate with the current in the output loop of another identical circuit, the invert function is performed
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
Rapid simultaneous high-resolution mapping of myelin water fraction and relaxation times in human brain using BMC-mcDESPOT.

Science.gov (United States)

Bouhrara, Mustapha; Spencer, Richard G

2017-02-15

A number of central nervous system (CNS) diseases exhibit changes in myelin content and magnetic resonance longitudinal, T 1 , and transverse, T 2 , relaxation times, which therefore represent important biomarkers of CNS pathology. Among the methods applied for measurement of myelin water fraction (MWF) and relaxation times, the multicomponent driven equilibrium single pulse observation of T 1 and T 2 (mcDESPOT) approach is of particular interest. mcDESPOT permits whole brain mapping of multicomponent T 1 and T 2 , with data acquisition accomplished within a clinically realistic acquisition time. Unfortunately, previous studies have indicated the limited performance of mcDESPOT in the setting of the modest signal-to-noise range of high-resolution mapping, required for the depiction of small structures and to reduce partial volume effects. Recently, we showed that a new Bayesian Monte Carlo (BMC) analysis substantially improved determination of MWF from mcDESPOT imaging data. However, our previous study was limited in that it did not discuss determination of relaxation times. Here, we extend the BMC analysis to the simultaneous determination of whole-brain MWF and relaxation times using the two-component mcDESPOT signal model. Simulation analyses and in-vivo human brain studies indicate the overall greater performance of this approach compared to the stochastic region contraction (SRC) algorithm, conventionally used to derive parameter estimates from mcDESPOT data. SRC estimates of the transverse relaxation time of the long T 2 fraction, T 2,l , and the longitudinal relaxation time of the short T 1 fraction, T 1,s , clustered towards the lower and upper parameter search space limits, respectively, indicating failure of the fitting procedure. We demonstrate that this effect is absent in the BMC analysis. Our results also showed improved parameter estimation for BMC as compared to SRC for high-resolution mapping. Overall we find that the combination of BMC analysis
On integral representation, relaxation and homogenization for unbounded functionals

International Nuclear Information System (INIS)

Carbone, L.; De Arcangelis, R.

1997-01-01

A theory of integral representation, relaxation and homogenization for some types of variational functionals taking extended real values and possibly being not finite also on large classes of regular functions is presented. Some applications to gradient constrained relaxation and homogenization problems are given
Internal structures of self-organized relaxed states and self-similar decay phase

International Nuclear Information System (INIS)

Kondoh, Yoshiomi

1992-03-01

A thought analysis on relaxation due to nonlinear processes is presented to lead to a set of general thoughts applicable to general nonlinear dynamical systems for finding out internal structures of the self-organized relaxed state without using 'invariant'. Three applications of the set of general thoughts to energy relaxations in resistive MHD plasmas, incompressible viscous fluids, and incompressible viscous MHD fluids are shown to lead to the internal structures of the self-organized relaxed states. It is shown that all of the relaxed states in these three dynamical systems are followed by self-similar decay phase without significant change of the spatial structure. The well known relaxed state of ∇ x B = ±λ B is shown to be derived generally in the low β plasma limit. (author)
Exploring multicollinearity using a random matrix theory approach.

Science.gov (United States)

Feher, Kristen; Whelan, James; Müller, Samuel

2012-01-01

Clustering of gene expression data is often done with the latent aim of dimension reduction, by finding groups of genes that have a common response to potentially unknown stimuli. However, what is poorly understood to date is the behaviour of a low dimensional signal embedded in high dimensions. This paper introduces a multicollinear model which is based on random matrix theory results, and shows potential for the characterisation of a gene cluster's correlation matrix. This model projects a one dimensional signal into many dimensions and is based on the spiked covariance model, but rather characterises the behaviour of the corresponding correlation matrix. The eigenspectrum of the correlation matrix is empirically examined by simulation, under the addition of noise to the original signal. The simulation results are then used to propose a dimension estimation procedure of clusters from data. Moreover, the simulation results warn against considering pairwise correlations in isolation, as the model provides a mechanism whereby a pair of genes with `low' correlation may simply be due to the interaction of high dimension and noise. Instead, collective information about all the variables is given by the eigenspectrum.
Estimation of covariance matrix on the experimental data for nuclear data evaluation

International Nuclear Information System (INIS)

Murata, T.

1985-01-01

In order to evaluate fission and capture cross sections of some U and Pu isotopes for JENDL-3, we have a plan for evaluating them simultaneously with a least-squares method. For the simultaneous evaluation, the covariance matrix is required for each experimental data set. In the present work, we have studied the procedures for deriving the covariance matrix from the error data given in the experimental papers. The covariance matrices were obtained using the partial errors and estimated correlation coefficients between the same type partial errors for different neutron energy. Some examples of the covariance matrix estimation are explained and the preliminary results of the simultaneous evaluation are presented. (author)
Matrix Training of Receptive Language Skills with a Toddler with Autism Spectrum Disorder: A Case Study

Science.gov (United States)

Curiel, Emily S. L.; Sainato, Diane M.; Goldstein, Howard

2016-01-01

Matrix training is a systematic teaching approach that can facilitate generalized language. Specific responses are taught that result in the emergence of untrained responses. This type of training facilitates the use of generalized language in children with autism spectrum disorder (ASD). This study used a matrix training procedure with a toddler…
Randomized comparison of operator radiation exposure comparing transradial and transfemoral approach for percutaneous coronary procedures: rationale and design of the minimizing adverse haemorrhagic events by TRansradial access site and systemic implementation of angioX - RAdiation Dose study (RAD-MATRIX).

Science.gov (United States)

Sciahbasi, Alessandro; Calabrò, Paolo; Sarandrea, Alessandro; Rigattieri, Stefano; Tomassini, Francesco; Sardella, Gennaro; Zavalloni, Dennis; Cortese, Bernardo; Limbruno, Ugo; Tebaldi, Matteo; Gagnor, Andrea; Rubartelli, Paolo; Zingarelli, Antonio; Valgimigli, Marco

2014-06-01

Radiation absorbed by interventional cardiologists is a frequently under-evaluated important issue. Aim is to compare radiation dose absorbed by interventional cardiologists during percutaneous coronary procedures for acute coronary syndromes comparing transradial and transfemoral access. The randomized multicentre MATRIX (Minimizing Adverse Haemorrhagic Events by TRansradial Access Site and Systemic Implementation of angioX) trial has been designed to compare the clinical outcome of patients with acute coronary syndromes treated invasively according to the access site (transfemoral vs. transradial) and to the anticoagulant therapy (bivalirudin vs. heparin). Selected experienced interventional cardiologists involved in this study have been equipped with dedicated thermoluminescent dosimeters to evaluate the radiation dose absorbed during transfemoral or right transradial or left transradial access. For each access we evaluate the radiation dose absorbed at wrist, at thorax and at eye level. Consequently the operator is equipped with three sets (transfemoral, right transradial or left transradial access) of three different dosimeters (wrist, thorax and eye dosimeter). Primary end-point of the study is the procedural radiation dose absorbed by operators at thorax. An important secondary end-point is the procedural radiation dose absorbed by operators comparing the right or left radial approach. Patient randomization is performed according to the MATRIX protocol for the femoral or radial approach. A further randomization for the radial approach is performed to compare right and left transradial access. The RAD-MATRIX study will probably consent to clarify the radiation issue for interventional cardiologist comparing transradial and transfemoral access in the setting of acute coronary syndromes. Copyright © 2014 Elsevier Inc. All rights reserved.
Matrix-induced autologous chondrocyte implantation for a large chondral defect in a professional football player: a case report

Directory of Open Access Journals (Sweden)

Beyzadeoglu Tahsin

2012-06-01

Full Text Available Abstract Introduction Matrix-assisted autologous chondrocyte implantation is a well-known procedure for the treatment of cartilage defects, which aims to establish a regenerative milieu and restore hyaline cartilage. However, much less is known about third-generation autologous chondrocyte implantation application in high-level athletes. We report on the two-year follow-up outcome after matrix-assisted autologous chondrocyte implantation to treat a large cartilage lesion of the lateral femoral condyle in a male Caucasian professional football player. Case presentation A 27-year-old male Caucasian professional football player was previously treated for cartilage problems of his left knee with two failed microfracture procedures resulting in a 9 cm2 Outerbridge Grade 4 chondral lesion at his lateral femoral condyle. Preoperative Tegner-Lysholm and Brittberg-Peterson scores were 64 and 58, and by the second year they were 91 and 6. An evaluation with magnetic resonance imaging demonstrated filling of the defect with the signal intensity of the repair tissue resembling healthy cartilage. Second-look arthroscopy revealed robust, smooth cartilage covering his lateral femoral condyle. He returned to his former competitive level without restrictions or complaints one year after the procedure. Conclusions This case illustrates that robust cartilage tissue can be obtained with a matrix-assisted autologous chondrocyte implantation procedure even after two failed microfracture procedures in a large (9 cm2 cartilage defect. To the best of our knowledge, this is the first case report on the application of the third-generation cell therapy treatment technique, matrix-assisted autologous chondrocyte implantation, in a professional football player.
CdZnTe quantum dots study: energy and phase relaxation process

International Nuclear Information System (INIS)

Viale, Yannick

2004-01-01

We present a study of the electron-hole pair energy and phase relaxation processes in a CdTe/ZnTe heterostructure, in which quantum dots are embedded. CdZnTe quantum wells with a high Zinc concentration, separated by ZnTe barriers, contain islands with a high cadmium concentration. In photoluminescence excitation spectroscopy experiments, we evidence two types of electron hole pair relaxation processes. After being excited in the CdZnTe quantum well, the pairs relax their energy by emitting a cascade of longitudinal optical phonons until they are trapped in the quantum dots. Before their radiative recombination follows an intra-dot relaxation, which is attributed to a lattice polarization mechanism of the quantum dots. It is related to the coupling between the electronic and the vibrational states. Both relaxation mechanisms are reinforced by the strong polar character of the chemical bond in II-VI compounds. Time resolved measurements of transmission variations in a pump-probe configuration allowed us to investigate the population dynamics of the electron-hole pairs during the relaxation process. We observe a relaxation time of about 2 ps for the longitudinal phonon emission cascade in the quantum well before a saturation of the quantum dot transition. We also measured an intra-box relaxation time of 25 ps. The comparison of various cascades allows us to estimate the emission time of a longitudinal optical phonon in the quantum well to be about 100 fs. In four waves mixing experiments, we observe oscillations that we attribute to quantum beats between excitonic and bi-excitonic transitions. The dephasing times that we measure as function of the density of photons shows that excitons are strongly localized in the quantum dots. The excitonic dephasing time is much shorter than the radiative lifetime and is thus controlled by the intra-dot relaxation time. (author) [fr

Submicron beam X-ray diffraction of nanoheteroepitaxily grown GaN: Experimental challenges and calibration procedures

Energy Technology Data Exchange (ETDEWEB)

Bonanno, P.L., E-mail: PeterBonanno@gatech.ed [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Gautier, S. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Sirenko, A.A. [Department of Physics, New Jersey Institute of Technology, Newark, NJ 07102 (United States); Kazimirov, A. [Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, New York 14853 (United States); Cai, Z.-H. [Advanced Photon Source, 9700 S. Cass Avenue, Argonne, IL 60439 (United States); Goh, W.H. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France); Martin, J. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Martinez, A. [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Moudakir, T. [Laboratoire Materiaux Optiques, Photonique et Micro-Nano Systemes, UMR CNRS 7132, Universite de Metz et SUPELEC, 2 rue E. Belin, 57070 Metz (France); Maloufi, N. [Laboratoire d' Etude des Textures et Application aux Materiaux, UMR CNRS 7078, Ile du Saulcy, 57045 Metz Cedex 1 (France); Assouar, M.B. [Laboratoire de Physique des Milieux Ionises et Applications, Nancy University, CNRS, BP 239, F-54506 Vandoeuvre-les-Nancy Cedex (France); Ramdane, A.; Gratiet, L. Le [Laboratoire de Photonique et de Nanostructures, UPR CNRS 20, Route de Nozay, 91460 Marcoussis (France); Ougazzaden, A. [Georgia Institute of Technology/GTL, UMI 2958 Georgia Tech-CNRS, 57070 Metz (France)

2010-02-15

Highly relaxed GaN nanodots and submicron ridges have been selectively grown in the NSAG regime using MOVPE on lattice mismatched 6H-SiC and AlN substrates. 2D real space and 3D reciprocal space mapping was performed with a CCD detector using 10.4 keV synchrotron X-ray radiation at the 2-ID-D micro-diffraction beamline at Advanced Photon Source (APS). Calibration procedures have been developed to overcome the unique challenges of analyzing NSAG structures grown on highly mismatched substrates. We studied crystallographic planar bending on the submicron scale and found its correlation with strain relaxation in the NSAG ridges.
The shear and bulk relaxation times from the general correlation functions

Science.gov (United States)

Czajka, Alina; Jeon, Sangyong

2017-11-01

In this paper we present two quantum field theoretical analyses on the shear and bulk relaxation times. First, we discuss how to find Kubo formulas for the shear and the bulk relaxation times. Next, we provide results on the shear viscosity relaxation time obtained within the diagrammatic approach for the massless λϕ4 theory.
Glass transition and relaxation dynamics of propylene glycol-water solutions confined in clay

Science.gov (United States)

Elamin, Khalid; Björklund, Jimmy; Nyhlén, Fredrik; Yttergren, Madeleine; Mârtensson, Lena; Swenson, Jan

2014-07-01

The molecular dynamics of aqueous solutions of propylene glycol (PG) and propylene glycol methylether (PGME) confined in a two-dimensional layer-structured Na-vermiculite clay has been studied by broadband dielectric spectroscopy and differential scanning calorimetry. As typical for liquids in confined geometries the intensity of the cooperative α-relaxation becomes considerably more suppressed than the more local β-like relaxation processes. In fact, at high water contents the calorimetric glass transition and related structural α-relaxation cannot even be observed, due to the confinement. Thus, the intensity of the viscosity related α-relaxation is dramatically reduced, but its time scale as well as the related glass transition temperature Tg are for both systems only weakly influenced by the confinement. In the case of the PGME-water solutions it is an important finding since in the corresponding bulk system a pronounced non-monotonic concentration dependence of the glass transition related dynamics has been observed due to the growth of hydrogen bonded relaxing entities of water bridging between PGME molecules [J. Sjöström, J. Mattsson, R. Bergman, and J. Swenson, Phys. Chem. B 115, 10013 (2011)]. The present results suggest that the same type of structural entities are formed in the quasi-two-dimensional space between the clay platelets. It is also observed that the main water relaxation cannot be distinguished from the β-relaxation of PG or PGME in the concentration range up to intermediate water contents. This suggests that these two processes are coupled and that the water molecules affect the time scale of the β-relaxation. However, this is most likely true also for the corresponding bulk solutions, which exhibit similar time scales of this combined relaxation process below Tg. Finally, it is found that at higher water contents the water relaxation does not merge with, or follow, the α-relaxation above Tg, but instead crosses the α-relaxation
Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

Science.gov (United States)

Pfeiffer, M.; Nizenkov, P.; Mirza, A.; Fasoulas, S.

2016-02-01

Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn's Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder.
Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

International Nuclear Information System (INIS)

Pfeiffer, M.; Nizenkov, P.; Mirza, A.; Fasoulas, S.

2016-01-01

Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn’s Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder
Direct simulation Monte Carlo modeling of relaxation processes in polyatomic gases

Energy Technology Data Exchange (ETDEWEB)

Pfeiffer, M., E-mail: mpfeiffer@irs.uni-stuttgart.de; Nizenkov, P., E-mail: nizenkov@irs.uni-stuttgart.de; Mirza, A., E-mail: mirza@irs.uni-stuttgart.de; Fasoulas, S., E-mail: fasoulas@irs.uni-stuttgart.de [Institute of Space Systems, University of Stuttgart, Pfaffenwaldring 29, D-70569 Stuttgart (Germany)

2016-02-15

Relaxation processes of polyatomic molecules are modeled and implemented in an in-house Direct Simulation Monte Carlo code in order to enable the simulation of atmospheric entry maneuvers at Mars and Saturn’s Titan. The description of rotational and vibrational relaxation processes is derived from basic quantum-mechanics using a rigid rotator and a simple harmonic oscillator, respectively. Strategies regarding the vibrational relaxation process are investigated, where good agreement for the relaxation time according to the Landau-Teller expression is found for both methods, the established prohibiting double relaxation method and the new proposed multi-mode relaxation. Differences and applications areas of these two methods are discussed. Consequently, two numerical methods used for sampling of energy values from multi-dimensional distribution functions are compared. The proposed random-walk Metropolis algorithm enables the efficient treatment of multiple vibrational modes within a time step with reasonable computational effort. The implemented model is verified and validated by means of simple reservoir simulations and the comparison to experimental measurements of a hypersonic, carbon-dioxide flow around a flat-faced cylinder.
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.
Non-monotonic behaviour in relaxation dynamics of image restoration

International Nuclear Information System (INIS)

Ozeki, Tomoko; Okada, Masato

2003-01-01

We have investigated the relaxation dynamics of image restoration through a Bayesian approach. The relaxation dynamics is much faster at zero temperature than at the Nishimori temperature where the pixel-wise error rate is minimized in equilibrium. At low temperature, we observed non-monotonic development of the overlap. We suggest that the optimal performance is realized through premature termination in the relaxation processes in the case of the infinite-range model. We also performed Markov chain Monte Carlo simulations to clarify the underlying mechanism of non-trivial behaviour at low temperature by checking the local field distributions of each pixel
Relaxation towards phase-locked dynamics in long Josephson junctions

DEFF Research Database (Denmark)

Salerno, M.; Grønbech-Jensen, Niels; Samuelsen, Mogens Rugholm

1995-01-01

We study the relaxation phenomenon towards phase-locked dynamics in long Josephson junctions. In particular the dependence of the relaxation frequency for the equal time of flight solution on the junction parameters is derived. The analysis is based on a phase-locked map and is compared with direct...... numerical experiments performed both on the map and on the perturbed sine-Gordon equation. As an interesting result we find that very close to a bifurcation the relaxation frequency is exactly equal to the half of the step frequency, i.e., the frequency characterizing the period-one solution....
Improvement and Validation of Weld Residual Stress Modelling Procedure

International Nuclear Information System (INIS)

Zang, Weilin; Gunnars, Jens; Dong, Pingsha; Hong, Jeong K.

2009-06-01

The objective of this work is to identify and evaluate improvements for the residual stress modelling procedure currently used in Sweden. There is a growing demand to eliminate any unnecessary conservatism involved in residual stress assumptions. The study was focused on the development and validation of an improved weld residual stress modelling procedure, by taking advantage of the recent advances in residual stress modelling and stress measurement techniques. The major changes applied in the new weld residual stress modelling procedure are: - Improved procedure for heat source calibration based on use of analytical solutions. - Use of an isotropic hardening model where mixed hardening data is not available. - Use of an annealing model for improved simulation of strain relaxation in re-heated material. The new modelling procedure is demonstrated to capture the main characteristics of the through thickness stress distributions by validation to experimental measurements. Three austenitic stainless steel butt-welds cases are analysed, covering a large range of pipe geometries. From the cases it is evident that there can be large differences between the residual stresses predicted using the new procedure, and the earlier procedure or handbook recommendations. Previously recommended profiles could give misleading fracture assessment results. The stress profiles according to the new procedure agree well with the measured data. If data is available then a mixed hardening model should be used
Improvement and Validation of Weld Residual Stress Modelling Procedure

Energy Technology Data Exchange (ETDEWEB)

Zang, Weilin; Gunnars, Jens (Inspecta Technology AB, Stockholm (Sweden)); Dong, Pingsha; Hong, Jeong K. (Center for Welded Structures Research, Battelle, Columbus, OH (United States))

2009-06-15

The objective of this work is to identify and evaluate improvements for the residual stress modelling procedure currently used in Sweden. There is a growing demand to eliminate any unnecessary conservatism involved in residual stress assumptions. The study was focused on the development and validation of an improved weld residual stress modelling procedure, by taking advantage of the recent advances in residual stress modelling and stress measurement techniques. The major changes applied in the new weld residual stress modelling procedure are: - Improved procedure for heat source calibration based on use of analytical solutions. - Use of an isotropic hardening model where mixed hardening data is not available. - Use of an annealing model for improved simulation of strain relaxation in re-heated material. The new modelling procedure is demonstrated to capture the main characteristics of the through thickness stress distributions by validation to experimental measurements. Three austenitic stainless steel butt-welds cases are analysed, covering a large range of pipe geometries. From the cases it is evident that there can be large differences between the residual stresses predicted using the new procedure, and the earlier procedure or handbook recommendations. Previously recommended profiles could give misleading fracture assessment results. The stress profiles according to the new procedure agree well with the measured data. If data is available then a mixed hardening model should be used
Isochronous relaxation curves for type 304 stainless steel after monotonic and cyclic strain

International Nuclear Information System (INIS)

Swindeman, R.W.

1978-01-01

Relaxation tests to 100 hr were performed on type 304 stainless steel in the temperature range 480 to 650 0 C and were used to develop isochronous relaxation curves. Behavior after monotonic and cyclic strain was compared. Relaxation differed only slightly as a consequence of the type of previous strain, provided that plastic flow preceded the relaxation period. We observed that the short-time relaxation behavior did not manifest strong heat-to-heat variation in creep strength
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.
Levitation force relaxation under reloading in a HTS Maglev system

International Nuclear Information System (INIS)

He Qingyong; Wang Jiasu; Wang Suyu; Wang Jiansi; Dong Hao; Wang Yuxin; Shao Senhao

2009-01-01

The loading capacity of the high-temperature superconducting (HTS) Maglev vehicle is an important parameter in the practical application. It is closely related to the levitation force of the HTS bulk. Many papers reported that the levitation force showed the relaxation characteristic. Because different loads cause different levitation gaps and different applied magnetic fields, the levitation force relaxations under the different loads are not the same. In terms of cylindrical YBCO bulk levitated over the permanent magnetic guideway, the relationship between the levitation force relaxation and the reloading is investigated experimentally in this paper. The decrement, the decrement rate and the relaxation rate of the levitation force are calculated, respectively. This work might be helpful for studying the loading capacity of the HTS Maglev vehicle
Levitation force relaxation under reloading in a HTS Maglev system

Energy Technology Data Exchange (ETDEWEB)

He Qingyong [Applied Superconductivity Laboratory, M/S 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: hedoubling@gmail.com; Wang Jiasu; Wang Suyu; Wang Jiansi; Dong Hao; Wang Yuxin; Shao Senhao [Applied Superconductivity Laboratory, M/S 152, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China)

2009-02-01

The loading capacity of the high-temperature superconducting (HTS) Maglev vehicle is an important parameter in the practical application. It is closely related to the levitation force of the HTS bulk. Many papers reported that the levitation force showed the relaxation characteristic. Because different loads cause different levitation gaps and different applied magnetic fields, the levitation force relaxations under the different loads are not the same. In terms of cylindrical YBCO bulk levitated over the permanent magnetic guideway, the relationship between the levitation force relaxation and the reloading is investigated experimentally in this paper. The decrement, the decrement rate and the relaxation rate of the levitation force are calculated, respectively. This work might be helpful for studying the loading capacity of the HTS Maglev vehicle.
Point defect relaxation volumes for copper

International Nuclear Information System (INIS)

Miller, K.M.

1979-11-01

The methods used for the determination of point defect relaxation volumes are discussed and it is shown that a previous interatomic potential derived for copper is inaccurate and results obtained using it are invalid. A new interatomic potential has been produced for copper and a computer simulation of point and planar defects carried out. A vacancy relaxation volume of -0.33 atomic volumes has been found with interstitial values in the range 1.7 to 2.0 atomic volumes. It is shown that these values in current theories of irradiation induced swelling lead to an anomalously high value for dislocation bias compared with that determined experimentally. (author)
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.
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.
Relaxation model of radiation-induced conductivity in polymers

Science.gov (United States)

Zhutayeva, Yu. R.; Khatipov, S. A.

1999-05-01

The paper suggests a relaxation model of radiation-induced conductivity (RIC) in polymers. According to the model, the transfer of charges generated in the polymer volume by ionizing radiation takes place with the participation of molecular relaxation processes. The mechanism of electron transport consists in the transfer of the charge directly between traps when they draw close to one another due to the rotation of macromolecule segments. The numerical solutions of the corresponding kinetic equations for different distribution functions Q( τ) of the times of molecular relaxation and for different functions of the probability P( τ, τ') of charge transfer in the `overlapping' regions of the diffusion spheres of the segments are analyzed. The relaxation model provides an explanation of the non-Arrhenius behavior of the RIC temperature dependence, the power dependence of RIC on the dose rate with a power index in the interval 0.5-1.0, the appearance of maxima in the curves of the RIC temporal dependence and their irreversible character in the region of large dose rates (more than 1 Gy/s). The model can be used for interpreting polymer RIC in conditions of kinetic mobility of macromolecules.

Optimal relaxed causal sampler using sampled-date system theory

NARCIS (Netherlands)

Shekhawat, Hanumant; Meinsma, Gjerrit

This paper studies the design of an optimal relaxed causal sampler using sampled data system theory. A lifted frequency domain approach is used to obtain the existence conditions and the optimal sampler. A state space formulation of the results is also provided. The resulting optimal relaxed causal
Noninteracting control of nonlinear systems based on relaxed control

NARCIS (Netherlands)

Jayawardhana, B.

2010-01-01

In this paper, we propose methodology to solve noninteracting control problem for general nonlinear systems based on the relaxed control technique proposed by Artstein. For a class of nonlinear systems which cannot be stabilized by smooth feedback, a state-feedback relaxed control can be designed to
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.
[Neurophysiologic and respiratory changes during the practice of relaxation technics].

Science.gov (United States)

Gallois, P

1984-01-01

A polygraphic study, of 40 minutes duration, among 10 subjects who practiced autogenic training (TA) and 10 subjects who practiced transcendental meditation (MT), compared to 10 control subjects, gave the following results: rarity of the number of sleeping episodes during relaxation, cardiac rhythm, significantly decreased in the TM group, increased stability of the E.D.G. during and after relaxation, respiratory rate decreased to a value of 33% of the initial rate, respiratory suspensions were frequent in the TM group, reaching a maximal duration of 50 seconds. The absence of compensatory hypercapnia and hyperpnea is an argument in favor of their central origin, lastly, the simple reaction time after relaxation is slightly decreased, whereas it is increased in the controls, this aerobic hypometabolic state, the stability of the autonomic nervous system and the maintenance of the vigilance, induced by deep relaxation, seems to be the opposite of the state which is induced by stress; therefore deep relaxation may play a role in a psycho-somatic approach to treating a variety of disease states.
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)
Global quantum discord and matrix product density operators

Science.gov (United States)

Huang, Hai-Lin; Cheng, Hong-Guang; Guo, Xiao; Zhang, Duo; Wu, Yuyin; Xu, Jian; Sun, Zhao-Yu

2018-06-01

In a previous study, we have proposed a procedure to study global quantum discord in 1D chains whose ground states are described by matrix product states [Z.-Y. Sun et al., Ann. Phys. 359, 115 (2015)]. In this paper, we show that with a very simple generalization, the procedure can be used to investigate quantum mixed states described by matrix product density operators, such as quantum chains at finite temperatures and 1D subchains in high-dimensional lattices. As an example, we study the global discord in the ground state of a 2D transverse-field Ising lattice, and pay our attention to the scaling behavior of global discord in 1D sub-chains of the lattice. We find that, for any strength of the magnetic field, global discord always shows a linear scaling behavior as the increase of the length of the sub-chains. In addition, global discord and the so-called "discord density" can be used to indicate the quantum phase transition in the model. Furthermore, based upon our numerical results, we make some reliable predictions about the scaling of global discord defined on the n × n sub-squares in the lattice.
Stress relaxation experiments on a lamellar polystyrene-polyisoprene diblock copolymer melt

DEFF Research Database (Denmark)

Holmqvist, P.; Castelletto, V.; Hamley, I.W.

2001-01-01

The non-linear rheology of the lamellar phase of a polystyrene-polyisoprene diblock copolymer is studied by oscillatory shear experiments. The relaxation of the shear modulus, G(t, gamma) is studied as a function of strain amplitude, gamma, up to large amplitude strains, gamma = 100%. The decay...... of G(t, gamma) is analysed using the model-independent CONTIN inverse Laplace transform algorithm to obtain a series of relaxation times, which reveals multiple relaxation processes. The timescale for the fastest relaxation processes is compared to those previously observed for diblock copolymer melts...... via dynamic light scattering experiments. The slowest relaxation process may be related to the shear-induced orientation of the lamellae. It is shown that time-strain separability G(t, gamma)= G(t)h(gamma) can be applied, and the damping function h(gamma) is consistent with a strongly strain...
Fetal responses to induced maternal relaxation during pregnancy

OpenAIRE

DiPietro, Janet A.; Costigan, Kathleen A.; Nelson, Priscilla; Gurewitsch, Edith D.; Laudenslager, Mark L.

2007-01-01

Fetal responses to induced maternal relaxation during the 32nd week of pregnancy were recorded in 100 maternal-fetal pairs using a digitized data collection system. The 18-minute guided imagery relaxation manipulation generated significant changes in maternal heart rate, skin conductance, respiration period, and respiratory sinus arrhythmia. Significant alterations in fetal neurobehavior were observed, including decreased fetal heart rate (FHR), increased FHR variability, suppression of fetal...
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.
A New Agile Radiating System Called Electromagnetic Band Gap Matrix Antenna

Directory of Open Access Journals (Sweden)

Hussein Abou Taam

2014-01-01

Full Text Available Civil and military applications are increasingly in need for agile antenna devices which respond to wireless telecommunications, radars, and electronic warfare requirements. The objective of this paper is to design a new agile antenna system called electromagnetic band gap (EBG matrix. The working principle of this antenna is based on the radiating aperture theory and constitutes the subject of an accepted CNRS patent. In order to highlight the interest and the originality of this antenna, we present a comparison between it and a classical patch array only for the (one-dimensional 1D configuration by using a rigorous full wave simulation (CST Microwave software. In addition, EBG matrix antenna can be controlled by specific synthesis algorithms. These algorithms use inside their; optimization loop an analysis procedure to evaluate the radiation pattern. The analysis procedure is described and validated at the end of this paper.
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.
Vibrational energy transfer in selectively excited diatomic molecules. [Relaxation rates, self-relaxation, upper limits

Energy Technology Data Exchange (ETDEWEB)

Dasch, C.J.

1978-09-01

Single rovibrational states of HCl(v=2), HBr(v=2), DCl(v=2), and CO(v=2) were excited with a pulsed optical parametric oscillator (OPO). Total vibrational relaxation rates near - resonance quenchers were measured at 295/sup 0/K using time resolved infrared fluorescence. These rates are attributed primarily to V - V energy transfer, and they generally conform to a simple energy gap law. A small deviation was found for the CO(v) + DCl(v') relaxation rates. Upper limits for the self relaxation by V - R,T of HCl(v=2) and HBr(v=2) and for the two quantum exchange between HCl and HBr were determined. The HF dimer was detected at 295/sup 0/K and 30 torr HF pressure with an optoacoustic spectrometer using the OPO. Pulsed and chopped, resonant and non-resonant spectrophones are analyzed in detail. From experiments and first order perturbation theory, these V - V exchange rates appear to behave as a first order perturbation in the vibrational coordinates. The rotational dynamics are known to be complicated however, and the coupled rotational - vibrational dynamics were investigated theoreticaly in infinite order by the Dillon and Stephenson and the first Magnus approximations. Large ..delta..J transitions appear to be important, but these calculations differ by orders of magnitude on specific rovibrational transition rates. Integration of the time dependent semiclassical equations by a modified Gordon method and a rotationally distorted wave approximation are discussed as methods which would treat the rotational motion more accurately. 225 references.
Curie-type paramagnetic NMR relaxation in the aqueous solution of Ni(II).

Science.gov (United States)

Mareš, Jiří; Hanni, Matti; Lantto, Perttu; Lounila, Juhani; Vaara, Juha

2014-04-21

Ni(2+)(aq) has been used for many decades as a model system for paramagnetic nuclear magnetic resonance (pNMR) relaxation studies. More recently, its magnetic properties and also nuclear magnetic relaxation rates have been studied computationally. We have calculated electron paramagnetic resonance and NMR parameters using quantum-mechanical (QM) computation of molecular dynamics snapshots, obtained using a polarizable empirical force field. Statistical averages of hyperfine coupling, g- and zero-field splitting tensors, as well as the pNMR shielding terms, are compared to the available experimental and computational data. In accordance with our previous work, the isotropic hyperfine coupling as well as nuclear shielding values agree well with experimental measurements for the (17)O nuclei of water molecules in the first solvation shell of the nickel ion, whereas larger deviations are found for (1)H centers. We report, for the first time, the Curie-type contribution to the pNMR relaxation rate using QM calculations together with Redfield relaxation theory. The Curie relaxation mechanism is analogous to chemical shift anisotropy relaxation, well-known in diamagnetic NMR. Due to the predominance of other types of paramagnetic relaxation mechanisms for this system, it is possible to extract the Curie term only computationally. The Curie mechanism alone would result in around 16 and 20 s(-1) of relaxation rates (R1 and R2 respectively) for the (1)H nuclei of water molecules bonded to the Ni(2+) center, in a magnetic field of 11.7 T. The corresponding (17)O relaxation rates are around 33 and 38 s(-1). We also report the Curie contribution to the relaxation rate for molecules beyond the first solvation shell in a 1 M solution of Ni(2+) in water.
Irradiation-induced stress relaxation of Eurofer97 steel

International Nuclear Information System (INIS)

Luzginova, N.V.; Jong, M.; Rensman, J.W.; Hegeman, J.B.J.; Laan, J.G. van der

2011-01-01

The irradiation-induced stress relaxation behavior of Eurofer97 at 300 deg. C up to 3.4 dpa and under pre-stress loads typical for the ITER applications is investigated. The bolt specimens are pre-loaded from 30% to 90% of the yield strength. To verify the results obtained with the pre-stressed bolts, bent strips were investigated as well. The strips are bent into a pre-defined radius in order to achieve similar pre-stress levels. The irradiation-induced stress relaxation is found to be independent of the pre-stress level. 10-12% of the stress relaxation in Eurofer97 may be reached after a dose of 0.1 dpa, and after an irradiation dose of 2.7 dpa 42-47% of the original pre-stress is retained.
Cross Relaxation in rare-earth-doped oxyfluoride glasses

Energy Technology Data Exchange (ETDEWEB)

Lakshminarayana, G.; Weis, Eric M. [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Lira, A.C. [Unidad Académica Profesional Nezahualcóyotl, Universidad Autónoma del Estado de México, Av. Bordo de Xochiaca s/n, Nezahualcóyotl, Estado de Mexico 57000, México (Mexico); Caldiño, Ulises [Departamento de Física, Universidad Autónoma Metropolitana-Iztapalapa, P.O. Box 55-534, México D.F. 09340 (Mexico); Williams, Darrick J. [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Hehlen, Markus P., E-mail: hehlen@lanl.gov [Materials Science and Technology Division (MST-7), Los Alamos National Laboratory, Los Alamos, NM 87545 (United States)

2013-07-15

The excited-state relaxation dynamics of Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} doped into a 50SiO{sub 2}–20Al{sub 2}O{sub 3}–10Na{sub 2}O–20LaF{sub 3} (mol%) oxyfluoride glass are studied. Multiphonon relaxation of the primary emitting states in Tb{sup 3+} ({sup 5}D{sub 3} and {sup 5}D{sub 4}), Sm{sup 3+} ({sup 4}G{sub 5/2}), and Eu{sup 3+} ({sup 5}D{sub 0}) was found to be negligible in the present host. The relaxation of Tb{sup 3+} ({sup 5}D{sub 4}) and Eu{sup 3+} ({sup 5}D{sub 0}) is dominated by radiative decay. For Tb{sup 3+} ({sup 5}D{sub 3}) and Sm{sup 3+} ({sup 4}G{sub 5/2}) in contrast, radiative relaxation is in competition with several non-radiative cross-relaxation processes. This competition was found to be particularly pronounced for the {sup 5}D{sub 3} excited state in Tb{sup 3+}, where a 124-fold decrease of the ({sup 5}D{sub 3}→{sup 7}F{sub 5})/({sup 5}D{sub 4}→{sup 7}F{sub 5}) emission intensity ratio and a ∼10-fold shortening of the {sup 5}D{sub 3} lifetime was observed upon increasing the Tb{sup 3+} concentration from 0.01% to 1%. The Tb{sup 3+} concentration dependence of {sup 5}D{sub 3} also points to some degree of ion aggregation in the “as quenched” glasses. A Judd–Ofelt intensity analysis was performed for Sm{sup 3+} and used to estimate the relative magnitude of {sup 4}G{sub 5/2} cross-relaxation processes. Four cross-relaxation processes in particular were identified to account for 92% of the total {sup 4}G{sub 5/2} non-radiative decay, and a 11% quantum efficiency was estimated for the {sup 4}G{sub 5/2} excited state. Non-exponentiality in the {sup 5}D{sub 0} decay of Eu{sup 3+} is evidence for several Eu{sup 3+} coordination environments in the glass host that manifest in different {sup 5}D{sub 0} decay constants because of the hypersensitivity of the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. -- Highlights: ► Tb{sup 3+}, Sm{sup 3+}, and Eu{sup 3+} were doped into a LaF{sub 3}-rich oxyfluoride glass. ► The
Residual stresses relaxation in surface-hardened half-space under creep conditions

Directory of Open Access Journals (Sweden)

Vladimir P. Radchenko

2015-09-01

Full Text Available We developed the method for solving the problem of residual stresses relaxation in surface-hardened layer of half-space under creep conditions. At the first stage we made the reconstruction of stress-strain state in half-space after plastic surface hardening procedure based on partial information about distribution for one residual stress tensor component experimentally detected. At the second stage using a numerical method we solve the problem of relaxation of self-balanced residual stresses under creep conditions. To solve this problem we introduce the following Cartesian system: x0y plane is aligned with hardened surface of half-space and 0z axis is directed to the depth of hardened layer. We also introduce the hypotheses of plane sections parallel to x0z and y0z planes. Detailed analysis of the problem has been done. Comparison of the calculated data with the corresponding test data was made for plane specimens (rectangular parallelepipeds made of EP742 alloy during T=650°C after the ultrasonic hardening with four hardening modes. We use half-space to model these specimens because penetration's depth of residual stresses is less than specimen general size in two digit exponent. There is enough correspondence of experimental and calculated data. It is shown that there is a decay (in modulus of pressing residual stresses under creep in 1.4–1.6 times.
The detection of influential subsets in linear regression using an influence matrix

OpenAIRE

Peña, Daniel; Yohai, Víctor J.

1991-01-01

This paper presents a new method to identify influential subsets in linear regression problems. The procedure uses the eigenstructure of an influence matrix which is defined as the matrix of uncentered covariance of the effect on the whole data set of deleting each observation, normalized to include the univariate Cook's statistics in the diagonal. It is shown that points in an influential subset will appear with large weight in at least one of the eigenvector linked to the largest eigenvalue...
Trapping hydrogen atoms from a neon-gas matrix: a theoretical simulation.

Science.gov (United States)

Bovino, S; Zhang, P; Kharchenko, V; Dalgarno, A

2009-08-07

Hydrogen is of critical importance in atomic and molecular physics and the development of a simple and efficient technique for trapping cold and ultracold hydrogen atoms would be a significant advance. In this study we simulate a recently proposed trap-loading mechanism for trapping hydrogen atoms released from a neon matrix. Accurate ab initio quantum calculations are reported of the neon-hydrogen interaction potential and the energy- and angular-dependent elastic scattering cross sections that control the energy transfer of initially cold atoms are obtained. They are then used to construct the Boltzmann kinetic equation, describing the energy relaxation process. Numerical solutions of the Boltzmann equation predict the time evolution of the hydrogen energy distribution function. Based on the simulations we discuss the prospects of the technique.
Spin Relaxation in GaAs: Importance of Electron-Electron Interactions

Directory of Open Access Journals (Sweden)

Gionni Marchetti

2014-04-01

Full Text Available We study spin relaxation in n-type bulk GaAs, due to the Dyakonov–Perel mechanism, using ensemble Monte Carlo methods. Our results confirm that spin relaxation time increases with the electronic density in the regime of moderate electronic concentrations and high temperature. We show that the electron-electron scattering in the non-degenerate regime significantly slows down spin relaxation. This result supports predictions by Glazov and Ivchenko. Most importantly, our findings highlight the importance of many-body interactions for spin dynamics: we show that only by properly taking into account electron-electron interactions within the simulations, results for the spin relaxation time—with respect to both electron density and temperature—will reach good quantitative agreement with corresponding experimental data. Our calculations contain no fitting parameters.
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...

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