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

International Nuclear Information System (INIS)

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

2011-01-01

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

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.

Observation of a Relaxed Plasma State in a Quasi-Infinite Cylinder

Science.gov (United States)

Gray, T.; Brown, M. R.; Dandurand, D.

2013-02-01

A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v≥50km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of ∇×B=λB.

Hydrodynamic Relaxation of an Electron Plasma to a Near-Maximum Entropy State

International Nuclear Information System (INIS)

Rodgers, D. J.; Servidio, S.; Matthaeus, W. H.; Mitchell, T. B.; Aziz, T.; Montgomery, D. C.

2009-01-01

Dynamical relaxation of a pure electron plasma in a Malmberg-Penning trap is studied, comparing experiments, numerical simulations and statistical theories of weakly dissipative two-dimensional (2D) turbulence. Simulations confirm that the dynamics are approximated well by a 2D hydrodynamic model. Statistical analysis favors a theoretical picture of relaxation to a near-maximum entropy state with constrained energy, circulation, and angular momentum. This provides evidence that 2D electron fluid relaxation in a turbulent regime is governed by principles of maximum entropy.

Observation of a relaxed plasma state in a quasi-infinite cylinder.

Science.gov (United States)

Gray, T; Brown, M R; Dandurand, D

2013-02-22

A helical relaxed plasma state is observed in a long cylindrical volume. The cylinder is long enough so that the predicted minimum energy state is a close approximation to the infinite cylinder solution. The plasma is injected at v ≥ 50 km/s by a coaxial magnetized plasma gun located at one end of the cylindrical volume. The relaxed state is rapidly attained in 1-2 axial Alfvén times after initiation of the plasma. Magnetic data are favorably compared with an analytical model. Magnetic data exhibit broadband fluctuations of the measured axial modes during the formation period. The broadband activity rapidly decays as the energy condenses into the lowest energy mode, which is in agreement with the minimum energy eigenstate of [Symbol: see text] × B = λB.

Motional spin relaxation in photoexcited triplet states

International Nuclear Information System (INIS)

Harryvan, D.; Faassen, E. van

1997-01-01

Transient EPR experiments were performed on photoexcited spin triplet states of the luminescent dye EOSIN-Y in diluted (order of 1 nMol) frozen propane-1-ol solutions at various temperatures. Photoexcitation was achieved by irradiation with intense, short laser pulses. The details of the spin relaxation, in particular the dependence on time, magnetic field and microwave field strength are all reproduced by a model which computes the total magnetization in a population of photoexcited triplet states undergoing random reorientational motion. Using this model, we estimated the motional correlation times to be around a microsecond. This timescale is two orders of magnitude slower than the phase memory time of the triplets. (author)

State of health assessment for lithium batteries based on voltage–time relaxation measure

International Nuclear Information System (INIS)

Baghdadi, Issam; Briat, Olivier; Gyan, Philippe; Vinassa, Jean Michel

2016-01-01

Highlights: • Calendar aging under different storage conditions for three different battery technologies studied. • Two scenarios of aging under power cycling at two different temperatures investigated for one battery technology. • Relaxation profile of battery voltage just after full charge is highly correlated to aging. • Linear dependence between just after charge open circuit voltage and remaining capacity demonstrated. • No computational method and direct prediction of battery state of health or remaining capacity. - Abstract: The performance of lithium batteries degrades over time. The degradation rate strongly depends on stress conditions during use and even at rest. Thus, accurate and rapid diagnosis of battery state of health (SOH) is necessary for electric vehicle manufacturers to manage their vehicle fleets and warranties. This paper demonstrates a simple method for assessing SOH related to battery energy capability (SOH E ). The presented method is based on the monitoring of U relax over aging. U relax is the open-circuit voltage of the battery measured after full charging and 30 min of rest. A linear dependence between U relax and remaining capacity is noted. This correlation is demonstrated for three different commercial battery technologies (different chemistries) aged under different calendar and power cycling aging conditions. It was determined that the difference between two U relax voltages measured at two different aging states is proportional to SOH E decay. The mean error of the linear model is less than 2% for certain cases. This method could also be a highly useful and rapid tool for a complete battery pack diagnosis.

Solid-state NMR paramagnetic relaxation enhancement immersion depth studies in phospholipid bilayers

KAUST Repository

Chu, Shidong

2010-11-01

A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2-stearoyl-sn-glycero-3-phosphocholine (PSPC) phospholipid bilayers as paramagnetic moieties and the resulting enhancements of the longitudinal relaxation (T1) times of 31P nuclei on the surface of the bilayers were measured by a standard inversion recovery pulse sequence. The 31P NMR spin-lattice relaxation times decrease steadily as the DOXYL spin label moves closer to the surface as well as the concentration of the spin-labeled lipids increase. The enhanced relaxation vs. the position and concentration of spin-labels indicate that PRE induced by the DOXYL spin label are significant to determine longer distances over the whole range of the membrane depths. When these data were combined with estimated correlation times τc, the r-6-weighted, time-averaged distances between the spin-labels and the 31P nuclei on the membrane surface were estimated. The application of using this solid-state NMR PRE approach coupled with site-directed spin labeling (SDSL) may be a powerful method for measuring membrane protein immersion depth. © 2010 Elsevier Inc. All rights reserved.

Beyond reliability, multi-state failure analysis of satellite subsystems: A statistical approach

International Nuclear Information System (INIS)

Castet, Jean-Francois; Saleh, Joseph H.

2010-01-01

Reliability is widely recognized as a critical design attribute for space systems. In recent articles, we conducted nonparametric analyses and Weibull fits of satellite and satellite subsystems reliability for 1584 Earth-orbiting satellites launched between January 1990 and October 2008. In this paper, we extend our investigation of failures of satellites and satellite subsystems beyond the binary concept of reliability to the analysis of their anomalies and multi-state failures. In reliability analysis, the system or subsystem under study is considered to be either in an operational or failed state; multi-state failure analysis introduces 'degraded states' or partial failures, and thus provides more insights through finer resolution into the degradation behavior of an item and its progression towards complete failure. The database used for the statistical analysis in the present work identifies five states for each satellite subsystem: three degraded states, one fully operational state, and one failed state (complete failure). Because our dataset is right-censored, we calculate the nonparametric probability of transitioning between states for each satellite subsystem with the Kaplan-Meier estimator, and we derive confidence intervals for each probability of transitioning between states. We then conduct parametric Weibull fits of these probabilities using the Maximum Likelihood Estimation (MLE) approach. After validating the results, we compare the reliability versus multi-state failure analyses of three satellite subsystems: the thruster/fuel; the telemetry, tracking, and control (TTC); and the gyro/sensor/reaction wheel subsystems. The results are particularly revealing of the insights that can be gleaned from multi-state failure analysis and the deficiencies, or blind spots, of the traditional reliability analysis. In addition to the specific results provided here, which should prove particularly useful to the space industry, this work highlights the importance

Spin-lattice relaxation in phosphorescent triplet state molecules

International Nuclear Information System (INIS)

Verbeek, P.J.F.

1979-01-01

The present thesis contains the results of a study of spin-lattice relaxation (SLR) in the photo-excited triplet state of aromatic molecules, dissolved in a molecular host crystal. It appears that SLR in phosphorescent triplet state molecules often is related to the presence of so-called (pseudo) localized phonons in the molecular mixed crystals. These local phonons can be thought to correspond with vibrations (librations) of the guest molecule in the force field of the surrounding host molecules. Since the intermolecular forces are relatively weak, the frequencies corresponding with these vibrations are relatively low and usually are of the order of 10-30 cm -1 . (Auth.)

Muon spin relaxation and nonmagnetic Kondo state in PrInAg2

International Nuclear Information System (INIS)

MacLaughlin, D. E.; Heffner, R. H.; Nieuwenhuys, G. J.; Canfield, P. C.; Amato, A.; Baines, C.; Schenck, A.; Luke, G. M.; Fudamoto, Y.; Uemura, Y. J.

2000-01-01

Muon spin relaxation experiments have been carried out in the Kondo compound PrInAg 2 . The zero-field muon relaxation rate is found to be independent of temperature between 0.1 and 10 K, which rules out a magnetic origin (spin freezing or a conventional Kondo effect) for the previously observed specific-heat anomaly at ∼0.5 K. At low temperatures the muon relaxation can be quantitatively understood in terms of the muon's interaction with nuclear magnetism, including hyperfine enhancement of the 141 Pr nuclear moment at low temperatures. This argues against a Pr 3+ ground-state electronic magnetic moment, and is strong evidence for the doublet Γ 3 crystalline-electric-field-split ground state required for a nonmagnetic route to heavy-electron behavior. The data imply the existence of an exchange interaction between neighboring Pr 3+ ions of the order of 0.2 K in temperature units, which should be taken into account in a complete theory of a nonmagnetic Kondo effect in PrInAg 2 . (c) 2000 The American Physical Society

Energy relaxation between low lying tunnel split spin-states of the single molecule magnet Ni4

Science.gov (United States)

de Loubens, G.; Chaves-O'Flynn, G. D.; Kent, A. D.; Ramsey, C.; Del Barco, E.; Beedle, C.; Hendrickson, D. N.

2007-03-01

We have developed integrated magnetic sensors to study quantum tunneling of magnetization (QTM) in single molecule magnet (SMMs) single crystals. These sensors incorporate a microstrip resonator (30 GHz) and a micro-Hall effect magnetometer. They have been used to investigate the relaxation rates between the 2 lowest lying tunnel split spin-states of the SMM Ni4 (S=4). EPR spectroscopy at 30 GHz and 0.4 K and concurrent magnetization measurements of several Ni4 single crystals are presented. EPR enables measurement of the energy splitting between the 2 lowest lying superposition states as a function of the longitudinal and transverse fields. The energy relaxation rate is determined in two ways. First, in cw microwave experiments the change in spin-population together with the microwave absorption directly gives the relaxation time from energy conservation in steady-state. Second, direct time-resolved measurements of the magnetization with pulsed microwave radiation have been performed. The relaxation time is found to vary by several orders of magnitude in different crystals, from a few seconds down to smaller than 100 μs. We discuss this and the form of the relaxation found for different crystals and pulse conditions.

Relaxation of helium levels excited by heavy ion impact: III.- Orientation by anisotropic relaxation of excited atoms in previously aligned states

International Nuclear Information System (INIS)

Chamoun, E.; Lombardi, M.; Carre, M.; Gaillard, M.L.

1977-01-01

In the last paper of this series devoted to relaxation phenomena in a low pressure cell of helium excited by an accelerated ion beam, experimental evidence is given for a new mechanism of transfer between alignment and orientation through anisotropic relaxation of initially aligned excited states. The theory predicting this effect is briefly outlined and then description is given of the exact experimental conditions to detect the circularly polarized component of the light emitted by the target excited in the 4 1 D level of He I by Na + impact [fr

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

Directory of Open Access Journals (Sweden)

Telles Shirley

2009-08-01

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

Relaxation height in energy landscapes : an application to multiple metastable states

NARCIS (Netherlands)

Cirillo, E.N.M.; Nardi, F.R.

2012-01-01

The study of systems with multiple (not necessarily degenerate) metastable states presents subtle difficulties from the mathematical point of view related to the variational problem that has to be solved in these cases. We introduce the notion of relaxation height in a general energy landscape and

Determining the structural relaxation times deep in the glassy state of the pharmaceutical Telmisartan

Energy Technology Data Exchange (ETDEWEB)

Adrjanowicz, K; Paluch, M [Institute of Physics, University of Silesia, Uniwersytecka 4, 40-007 Katowice (Poland); Ngai, K L [Naval Research Laboratory, Washington, DC 20375-5320 (United States)

2010-03-31

By using the dielectric relaxation method proposed recently by Casalini and Roland (2009 Phys. Rev. Lett. 102 035701), we were able to determine the structural alpha-relaxation times deep in the glassy state of the pharmaceutical, Telmisartan. Normally, deep in the glassy state tau{sub a}lpha is so long that it cannot be measured but tau{sub b}eta, which is usually much shorter, can be directly determined. The method basically takes advantage of the connection between the alpha-relaxation and the secondary beta-relaxation of the Johari-Goldstein kind, including a relation between their relaxation times tau{sub a}lpha and tau{sub b}eta, respectively. Thus, tau{sub a}lpha of Telmisartan were determined by monitoring the change of the dielectric beta-loss, epsilon'', with physical aging time at temperatures well below the vitrification temperature. The values of tau{sub a}lpha were compared with those expected by the coupling model (CM). Unequivocal comparison cannot be made in the case of Telmisartan because its beta-loss peak is extremely broad, and the CM predicts only an order of magnitude agreement between the primitive relaxation frequency and the beta-peak frequency. We also made an attempt to analyze all isothermal and aging susceptibility data after transformation into the electric modulus representation. The tau{sub a}lpha found in the glass state by using the method of Casalini and Roland in the modulus representation are similar to those obtained in the susceptibility representation. However, it is remarkable that the stretching parameter beta{sub KWWM} = 0.51 in the electric modulus representation gives more precise fits to the aging data than in the susceptibility representation with beta{sub KWW} = 0.61. Our results suggest that the electric modulus representation may be useful as an alternative to analyze aging data, especially in the case of highly polar glassformers having a large ratio of low frequency and high frequency dielectric

QM/MM studies on the excited-state relaxation mechanism of a semisynthetic dTPT3 base.

Science.gov (United States)

Guo, Wei-Wei; Zhang, Teng-Shuo; Fang, Wei-Hai; Cui, Ganglong

2018-02-14

Semisynthetic alphabets can potentially increase the genetic information stored in DNA through the formation of unusual base pairs. Recent experiments have shown that near-visible-light irradiation of the dTPT3 chromophore could lead to the formation of a reactive triplet state and of singlet oxygen in high quantum yields. However, the detailed excited-state relaxation paths that populate the lowest triplet state are unclear. Herein, we have for the first time employed the QM(MS-CASPT2//CASSCF)/MM method to explore the spectroscopic properties and excited-state relaxation mechanism of the aqueous dTPT3 chromophore. On the basis of the results, we have found that (1) the S 2 ( 1 ππ*) state of dTPT3 is the initially populated excited singlet state upon near-visible light irradiation; and (2) there are two efficient relaxation pathways to populate the lowest triplet state, i.e. T 1 ( 3 ππ*). In the first one, the S 2 ( 1 ππ*) system first decays to the S 1 ( 1 nπ*) state near the S 2 /S 1 conical intersection, which is followed by an efficient S 1 → T 1 intersystem crossing process at the S 1 /T 1 crossing point; in the second one, an efficient S 2 → T 2 intersystem crossing takes place first, and then, the T 2 ( 3 nπ*) system hops to the T 1 ( 3 ππ*) state through an internal conversion process at the T 2 /T 1 conical intersection. Moreover, an S 2 /S 1 /T 2 intersection region is found to play a vital role in the excited-state relaxation. These new mechanistic insights help in understanding the photophysics and photochemistry of unusual base pairs.

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.

Cybersecurity threats to satellite communications: Towards a typology of state actor responses

Science.gov (United States)

Housen-Couriel, Deborah

2016-11-01

Cybersecurity threats to satellite communications are a relatively new phenomenon, yet have quickly come to the forefront of concern for the sustainability of satellite systems due to the vulnerabilities that such threats may exploit and negatively impact. These vulnerabilities are mission-critical: they include launch systems, communications, telemetry, tracking and command, and mission completion. They and other aspects of satellite communications depend heavily on secure and resilient cyber capabilities for all stages of the satellite's lifespan. Because of the inherently global nature of both satellite and cyberspace activities, these capabilities rely significantly on international cooperation for setting a baseline of agreed legal norms that protect satellites and satellite communications. This critical cooperation is relevant during all mission phases, from planning to final wrap-up. Under optimal circumstances, the norms and standards protecting satellites and satellite transmissions are developed and enforced by those nation-state actors that are committed to system operability and overall mission sustainability for those satellites launched under their aegis and responsibility. However, when breaches of international law do occur in the form of hostile cyber events that cause damage to satellite communications, a range of measures should be available to the victim state, provided by the appropriate legal regime or regimes. This article proposes that a comprehensive and integrative multi-stakeholder review be undertaken in the near future of the measures available under international law for responding to hostile acts directed at satellite systems and communications, in a manner that takes into account both existing regimes of international law reviewed herein, as well as considerations of cybersecurity. These measures will depend upon the characterization of hostile interference with satellite transmissions in accordance with a proposed typology of

Solid-state NMR paramagnetic relaxation enhancement immersion depth studies in phospholipid bilayers

KAUST Repository

Chu, Shidong; Maltsev, Sergey B.; Emwas, Abdul-Hamid M.; Lorigan, Gary A.

2010-01-01

A new approach for determining the membrane immersion depth of a spin-labeled probe has been developed using paramagnetic relaxation enhancement (PRE) in solid-state NMR spectroscopy. A DOXYL spin label was placed at different sites of 1-palmitoyl-2

Nonlinear Uncertainty Propagation of Satellite State Error for Tracking and Conjunction Risk Assessment

Science.gov (United States)

2017-12-18

AFRL-RV-PS- AFRL-RV-PS- TR-2017-0177 TR-2017-0177 NONLINEAR UNCERTAINTY PROPAGATION OF SATELLITE STATE ERROR FOR TRACKING AND CONJUNCTION RISK...Uncertainty Propagation of Satellite State Error for Tracking and Conjunction Risk Assessment 5a. CONTRACT NUMBER FA9453-16-1-0084 5b. GRANT NUMBER...prediction and satellite conjunction analysis. Statistical approach utilizes novel methods to build better uncertainty state characterization in the context

Postearthquake relaxation after the 2004 M6 Parkfield, California, earthquake and rate-and-state friction

Science.gov (United States)

Savage, J.C.; Langbein, J.

2008-01-01

An unusually complete set of measurements (including rapid rate GPS over the first 10 days) of postseismic deformation is available at 12 continuous GPS stations located close to the epicenter of the 2004 M6.0 Parkfield earthquake. The principal component modes for the relaxation of the ensemble of those 12 GPS stations were determined. The first mode alone furnishes an adequate approximation to the data. Thus, the relaxation at all stations can be represented by the product of a common temporal function and distinct amplitudes for each component (north or east) of relaxation at each station. The distribution in space of the amplitudes indicates that the relaxation is dominantly strike slip. The temporal function, which spans times from about 5 min to 900 days postearthquake, can be fit by a superposition of three creep terms, each of the form ??l loge(1 + t/??l), with characteristic times ??, = 4.06, 0.11, and 0.0001 days. It seems likely that what is actually involved is a broad spectrum of characteristic times, the individual components of which arise from afterslip on different fault patches. Perfettini and Avouac (2004) have shown that an individual creep term can be explained by the spring-slider model with rate-dependent (no state variable) friction. The observed temporal function can also be explained using a single spring-slider model (i.e., single fault patch) that includes rate-and-state-dependent friction, a single-state variable, and either of the two commonly used (aging and slip) state evolution laws. In the latter fits, the rate-and-state friction parameter b is negative.

The feasibility of parameterizing four-state equilibria using relaxation dispersion measurements

International Nuclear Information System (INIS)

Li Pilong; Martins, Ilídio R. S.; Rosen, Michael K.

2011-01-01

Coupled equilibria play important roles in controlling information flow in biochemical systems, including allosteric molecules and multidomain proteins. In the simplest case, two equilibria are coupled to produce four interconverting states. In this study, we assessed the feasibility of determining the degree of coupling between two equilibria in a four-state system via relaxation dispersion measurements. A major bottleneck in this effort is the lack of efficient approaches to data analysis. To this end, we designed a strategy to efficiently evaluate the smoothness of the target function surface (TFS). Using this approach, we found that the TFS is very rough when fitting benchmark CPMG data to all adjustable variables of the four-state equilibria. After constraining a portion of the adjustable variables, which can often be achieved through independent biochemical manipulation of the system, the smoothness of TFS improves dramatically, although it is still insufficient to pinpoint the solution. The four-state equilibria can be finally solved with further incorporation of independent chemical shift information that is readily available. We also used Monte Carlo simulations to evaluate how well each adjustable parameter can be determined in a large kinetic and thermodynamic parameter space and how much improvement can be achieved in defining the parameters through additional measurements. The results show that in favorable conditions the combination of relaxation dispersion and biochemical manipulation allow the four-state equilibrium to be parameterized, and thus coupling strength between two processes to be determined.

Electron-Phonon Coupling and Resonant Relaxation from 1D and 1P States in PbS Quantum Dots.

Science.gov (United States)

Kennehan, Eric R; Doucette, Grayson S; Marshall, Ashley R; Grieco, Christopher; Munson, Kyle T; Beard, Matthew C; Asbury, John B

2018-05-31

Observations of the hot-phonon bottleneck, which is predicted to slow the rate of hot carrier cooling in quantum confined nanocrystals, have been limited to date for reasons that are not fully understood. We used time-resolved infrared spectroscopy to directly measure higher energy intraband transitions in PbS colloidal quantum dots. Direct measurements of these intraband transitions permitted detailed analysis of the electronic overlap of the quantum confined states that may influence their relaxation processes. In smaller PbS nanocrystals, where the hot-phonon bottleneck is expected to be most pronounced, we found that relaxation of parity selection rules combined with stronger electron-phonon coupling led to greater spectral overlap of transitions among the quantum confined states. This created pathways for fast energy transfer and relaxation that may bypass the predicted hot-phonon bottleneck. In contrast, larger, but still quantum confined nanocrystals did not exhibit such relaxation of the parity selection rules and possessed narrower intraband states. These observations were consistent with slower relaxation dynamics that have been measured in larger quantum confined systems. These findings indicated that, at small radii, electron-phonon interactions overcome the advantageous increase in energetic separation of the electronic states for PbS quantum dots. Selection of appropriately sized quantum dots, which minimize spectral broadening due to electron-phonon interactions while maximizing electronic state separation, is necessary to observe the hot-phonon bottleneck. Such optimization may provide a framework for achieving efficient hot carrier collection and multiple exciton generation.

A relaxation-projection method for compressible flows. Part I: The numerical equation of state for the Euler equations

International Nuclear Information System (INIS)

Saurel, Richard; Franquet, Erwin; Daniel, Eric; Le Metayer, Olivier

2007-01-01

A new projection method is developed for the Euler equations to determine the thermodynamic state in computational cells. It consists in the resolution of a mechanical relaxation problem between the various sub-volumes present in a computational cell. These sub-volumes correspond to the ones traveled by the various waves that produce states with different pressures, velocities, densities and temperatures. Contrarily to Godunov type schemes the relaxed state corresponds to mechanical equilibrium only and remains out of thermal equilibrium. The pressure computation with this relaxation process replaces the use of the conventional equation of state (EOS). A simplified relaxation method is also derived and provides a specific EOS (named the Numerical EOS). The use of the Numerical EOS gives a cure to spurious pressure oscillations that appear at contact discontinuities for fluids governed by real gas EOS. It is then extended to the computation of interface problems separating fluids with different EOS (liquid-gas interface for example) with the Euler equations. The resulting method is very robust, accurate, oscillation free and conservative. For the sake of simplicity and efficiency the method is developed in a Lagrange-projection context and is validated over exact solutions. In a companion paper [F. Petitpas, E. Franquet, R. Saurel, A relaxation-projection method for compressible flows. Part II: computation of interfaces and multiphase mixtures with stiff mechanical relaxation. J. Comput. Phys. (submitted for publication)], the method is extended to the numerical approximation of a non-conservative hyperbolic multiphase flow model for interface computation and shock propagation into mixtures

Relaxation and final-state structure in XPS of atoms, molecules, and metals

International Nuclear Information System (INIS)

Shirley, D.A.; Martin, R.L.; McFeely, F.R.; Kowalczyk, S.P.; Ley, L.

1975-03-01

Photoemission from a many-electron system is a many-electron process, even though the transition operator may affect only one electron directly. Relaxation and ''shake-up'' structure are related by a sum rule. When one is present, the other must be also. Shake-up structure is shown to be accurately predictable in atomic neon and molecular HF if the CI calculations are done carefully. In metals the sum rule also applies but final-state effects usually appear as relaxation energy, which is large even for valence electrons. Finally, in rare-earth metals discrete shake-up structure is observable in the 4p region. (7 figs, 30 refs) (auth)

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.

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

Navier--Stokes relaxation to sinh--Poisson states at finite Reynolds numbers

International Nuclear Information System (INIS)

Montgomery, D.; Shan, X.; Matthaeus, W.H.

1993-01-01

A mathematical framework is proposed in which it seems possible to justify the computationally-observed relaxation of a two-dimensional Navier--Stokes fluid to a ''most probable,'' or maximum entropy, state. The relaxation occurs at large but finite Reynolds numbers, and involves substantial decay of higher-order ideal invariants such as enstrophy. A two-fluid formulation, involving interpenetrating positive and negative vorticity fluxes (continuous and square integrable) is developed, and is shown to be intimately related to the passive scalar decay problem. Increasing interpenetration of the two fluids corresponds to the decay of vorticity flux due to viscosity. It is demonstrated numerically that, in two dimensions, passive scalars decay rapidly, relative to mean-square vorticity (enstrophy). This observation provides a basis for assigning initial data to the two-fluid field variables

Formation and relaxation of quasistationary states in particle systems with power-law interactions.

Science.gov (United States)

Marcos, B; Gabrielli, A; Joyce, M

2017-09-01

We explore the formation and relaxation of the so-called quasistationary states (QSS) for particle distributions in three dimensions interacting via an attractive radial pair potential V(r→∞)∼1/r^{γ} with γ>0, and either a soft core or hard core regularization at small r. In the first part of the paper, we generalize, for any spatial dimension d≥2, Chandrasekhar's approach for the case of gravity to obtain analytic estimates of the rate of collisional relaxation due to two-body collisions. The resultant relaxation rates indicate an essential qualitative difference depending on the integrability of the pair force at large distances: for γ>d-1, the rate diverges in the large particle number N (mean-field) limit, unless a sufficiently large soft core is present; for γsoft cores leading to the formation of QSS. We find, just as for the previously well studied case of gravity (which we also revisit), excellent agreement between the parametric dependence of the observed relaxation times and our analytic predictions. Further, as in the case of gravity, we find that the results indicate that, when large impact factors dominate, the appropriate cutoff is the size of the system (rather than, for example, the mean interparticle distance). Our results provide strong evidence that the existence of QSS is robust only for long-range interactions with a large distance behavior γstates will be conditioned strongly on the short-range properties of the interaction.

Tin Oxide Nanowires: The Influence of Trap States on Ultrafast Carrier Relaxation

Directory of Open Access Journals (Sweden)

Zervos Matthew

2009-01-01

Full Text Available Abstract We have studied the optical properties and carrier dynamics in SnO2nanowires (NWs with an average radius of 50 nm that were grown via the vapor–liquid solid method. Transient differential absorption measurements have been employed to investigate the ultrafast relaxation dynamics of photogenerated carriers in the SnO2NWs. Steady state transmission measurements revealed that the band gap of these NWs is 3.77 eV and contains two broad absorption bands. The first is located below the band edge (shallow traps and the second near the center of the band gap (deep traps. Both of these absorption bands seem to play a crucial role in the relaxation of the photogenerated carriers. Time resolved measurements suggest that the photogenerated carriers take a few picoseconds to move into the shallow trap states whereas they take ~70 ps to move from the shallow to the deep trap states. Furthermore the recombination process of electrons in these trap states with holes in the valence band takes ~2 ns. Auger recombination appears to be important at the highest fluence used in this study (500 μJ/cm2; however, it has negligible effect for fluences below 50 μJ/cm2. The Auger coefficient for the SnO2NWs was estimated to be 7.5 ± 2.5 × 10−31 cm6/s.

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

Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge-transfer-to-solvent

International Nuclear Information System (INIS)

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

2015-01-01

The charge-transfer-to-solvent dynamics (CTTS) and excited state relaxation mechanism of the solvated electron in methanol are studied by time-resolved photoelectron spectroscopy on a liquid methanol microjet by means of two-pulse and three-pulse experiments. In the two-pulse experiment, CTTS excitation is followed by a probe photoejection pulse. The resulting time-evolving photoelectron spectrum reveals multiple time scales characteristic of relaxation and geminate recombination of the initially generated electron which are consistent with prior results from transient absorption. In the three-pulse experiment, the relaxation dynamics of the solvated electron following electronic excitation are measured. The internal conversion lifetime of the excited electron is found to be 130 ± 40 fs, in agreement with extrapolated results from clusters and the non-adiabatic relaxation mechanism

Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge-transfer-to-solvent

Science.gov (United States)

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

2015-06-01

The charge-transfer-to-solvent dynamics (CTTS) and excited state relaxation mechanism of the solvated electron in methanol are studied by time-resolved photoelectron spectroscopy on a liquid methanol microjet by means of two-pulse and three-pulse experiments. In the two-pulse experiment, CTTS excitation is followed by a probe photoejection pulse. The resulting time-evolving photoelectron spectrum reveals multiple time scales characteristic of relaxation and geminate recombination of the initially generated electron which are consistent with prior results from transient absorption. In the three-pulse experiment, the relaxation dynamics of the solvated electron following electronic excitation are measured. The internal conversion lifetime of the excited electron is found to be 130 ± 40 fs, in agreement with extrapolated results from clusters and the non-adiabatic relaxation mechanism.

Dynamics of electron solvation in methanol: Excited state relaxation and generation by charge-transfer-to-solvent

Energy Technology Data Exchange (ETDEWEB)

Elkins, Madeline H.; Williams, Holly L. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Neumark, Daniel M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

2015-06-21

The charge-transfer-to-solvent dynamics (CTTS) and excited state relaxation mechanism of the solvated electron in methanol are studied by time-resolved photoelectron spectroscopy on a liquid methanol microjet by means of two-pulse and three-pulse experiments. In the two-pulse experiment, CTTS excitation is followed by a probe photoejection pulse. The resulting time-evolving photoelectron spectrum reveals multiple time scales characteristic of relaxation and geminate recombination of the initially generated electron which are consistent with prior results from transient absorption. In the three-pulse experiment, the relaxation dynamics of the solvated electron following electronic excitation are measured. The internal conversion lifetime of the excited electron is found to be 130 ± 40 fs, in agreement with extrapolated results from clusters and the non-adiabatic relaxation mechanism.

Let Me Relax: Toward Automated Sedentary State Recognition and Ubiquitous Mental Wellness Solutions

Directory of Open Access Journals (Sweden)

Vijay Rajanna

2018-12-01

Full Text Available Advances in ubiquitous computing technology improve workplace productivity, reduce physical exertion, but ultimately result in a sedentary work style. Sedentary behavior is associated with an increased risk of stress, obesity, and other health complications. Let Me Relax is a fully automated sedentary-state recognition framework using a smartwatch and smartphone, which encourages mental wellness through interventions in the form of simple relaxation techniques. The system was evaluated through a comparative user study of 22 participants split into a test and a control group. An analysis of NASA Task Load Index pre- and post- study survey revealed that test subjects who followed relaxation methods, showed a trend of both increased activity as well as reduced mental stress. Reduced mental stress was found even in those test subjects that had increased inactivity. These results suggest that repeated interventions, driven by an intelligent activity recognition system, is an effective strategy for promoting healthy habits, which reduce stress, anxiety, and other health risks associated with sedentary workplaces.

Formation probabilities and relaxation rates of muon states in germanium

International Nuclear Information System (INIS)

Clawson, C.W.; Haller, E.E.; Crowe, K.M.; Rosenblum, S.S.; Brewer, J.H.; British Columbia Univ., Vancouver

1981-01-01

We report the first results of a study of the muonium states in ultra-pure germanium crystals grown under a variety of conditions at Lawrence Berkeley Laboratory. Among the variations studied are: 1) Hydrogen, deuterium, or nitrogen atmosphere during growth; 2) Dislocation-free vs. dislocated crystals; 3) Grown from quartz, graphite, and pyrolytic graphite coated quartz crucibles; 4) n-type vs. p-type. We report a significant difference in the muonium relaxation rate between the dislocated and non-dislocated crystals. (orig.)

Electronic excited states and relaxation dynamics in polymer heterojunction systems

Science.gov (United States)

Ramon, John Glenn Santos

The potential for using conducting polymers as the active material in optoelectronic devices has come to fruition in the past few years. Understanding the fundamental photophysics behind their operations points to the significant role played by the polymer interface in their performance. Current device architectures involve the use of bulk heterojunctions which intimately blend the donor and acceptor polymers to significantly increase not only their interfacial surface area but also the probability of exciton formation within the vicinity of the interface. In this dissertation, we detail the role played by the interface on the behavior and performance of bulk heterojunction systems. First, we explore the relation between the exciton binding energy to the band offset in determining device characteristics. As a general rule, when the exciton binding energy is greater than the band offset, the exciton remains the lowest energy excited state leading to efficient light-emitting properties. On the other hand, if the offset is greater than the binding energy, charge separation becomes favorable leading to better photovoltaic behavior. Here, we use a Wannier function, configuration interaction based approach to examine the essential excited states and predict the vibronic absorption and emission spectra of the PPV/BBL, TFB/F8BT and PFB/F8BT heterojunctions. Our results underscore the role of vibrational relaxation in the formation of charge-transfer states following photoexcitation. In addition, we look at the relaxation dynamics that occur upon photoexcitation. For this, we adopt the Marcus-Hush semiclassical method to account for lattice reorganization in the calculation of the interconversion rates in TFB/F8BT and PFB/F8BT. We find that, while a tightly bound charge-transfer state (exciplex) remains the lowest excited state, a regeneration pathway to the optically active lowest excitonic state in TFB/F8BT is possible via thermal repopulation from the exciplex. Finally

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.

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.

Spin-lattice relaxation of individual solid-state spins

Science.gov (United States)

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

2018-03-01

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

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.

Transport relaxation measurements and glassy state effects in superconducting MgB2

International Nuclear Information System (INIS)

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

2008-01-01

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

China: Possible Missile Technology Transfers from U.S. Satellite Export Policy - Actions and Chronology

National Research Council Canada - National Science Library

Kan, Shirley A

2001-01-01

.... Some critics opposed satellite exports to China, while others were concerned that the Clinton Administration relaxed export controls and monitoring of commercial satellites in moving the licensing...

Surface Relaxation and Electronic States of Pt(111) Surface with Varying Slab Thickness

International Nuclear Information System (INIS)

Kaushal, Ashok K.; Mullick, Shanta; Ahluwalia, P. K.

2011-01-01

Surface relaxation and electronic DOS's of Pt(111) surface have been studied with varying slab thickness using ab-initio SIESTA method. We found the expansion in the top layer and contraction in the subsurface layers of Pt(111) surface. Our results match with the experimental results. Also observing electronic density of states we found that as we increase the thickness of slab, the PDOS of Pt(111) surface goes towards the bulk density of states and Fermi energy shifts towards the bulk fermi energy.

Steepest-entropy-ascent quantum thermodynamic modeling of the relaxation process of isolated chemically reactive systems using density of states and the concept of hypoequilibrium state

Science.gov (United States)

Li, Guanchen; von Spakovsky, Michael R.

2016-01-01

This paper presents a study of the nonequilibrium relaxation process of chemically reactive systems using steepest-entropy-ascent quantum thermodynamics (SEAQT). The trajectory of the chemical reaction, i.e., the accessible intermediate states, is predicted and discussed. The prediction is made using a thermodynamic-ensemble approach, which does not require detailed information about the particle mechanics involved (e.g., the collision of particles). Instead, modeling the kinetics and dynamics of the relaxation process is based on the principle of steepest-entropy ascent (SEA) or maximum-entropy production, which suggests a constrained gradient dynamics in state space. The SEAQT framework is based on general definitions for energy and entropy and at least theoretically enables the prediction of the nonequilibrium relaxation of system state at all temporal and spatial scales. However, to make this not just theoretically but computationally possible, the concept of density of states is introduced to simplify the application of the relaxation model, which in effect extends the application of the SEAQT framework even to infinite energy eigenlevel systems. The energy eigenstructure of the reactive system considered here consists of an extremely large number of such levels (on the order of 10130) and yields to the quasicontinuous assumption. The principle of SEA results in a unique trajectory of system thermodynamic state evolution in Hilbert space in the nonequilibrium realm, even far from equilibrium. To describe this trajectory, the concepts of subsystem hypoequilibrium state and temperature are introduced and used to characterize each system-level, nonequilibrium state. This definition of temperature is fundamental rather than phenomenological and is a generalization of the temperature defined at stable equilibrium. In addition, to deal with the large number of energy eigenlevels, the equation of motion is formulated on the basis of the density of states and a set of

Solid state proton spin-lattice relaxation in four structurally related organic molecules

International Nuclear Information System (INIS)

Beckmann, Peter A.; Burbank, Kendra S.; Lau, Matty M.W.; Ree, Jessica N.; Weber, Tracy L.

2003-01-01

We report and interpret the temperature dependence of the proton spin-lattice relaxation rate at 8.50 and 22.5 MHz in four polycrystalline solids composed of structurally related molecules: 2-ethylanthracene, 2-t-butylanthracene, 2-ethylanthraquinone, and 2-t-butylanthraquinone. We have been unable to grow single crystals and therefore do not know the crystal structures. Hence, we use the NMR relaxometry data to make predictions about the solid state structures. As expected, we are able to conclude that the ethyl groups do not reorient in the solid state but that the t-butyl groups do. The anthraquinones have a ''simpler'' structure than the anthracenes. The best dynamical models suggest that there is a unique crystallographic site for the t-butyl groups in 2-t-butylanthraquinone and two sites, each with half the molecules, for the ethyl groups in 2-ethylanthraquinone. There are also two sites in 2-ethylanthracene, but with unequal weights, suggesting four sites in the unit cell with lower symmetry than the two anthraquinones. Finally, the observed relaxation rate data in 2-t-butylanthracene is very complex and its interpretation demonstrates the uniqueness problem that arises in interpreting relaxometry data without the knowledge of the crystal structure

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.

Magnetic flux conversion and relaxation toward a minimum-energy state in S-1 spheromak plasmas

International Nuclear Information System (INIS)

Janos, A.

1985-09-01

S-1 Spheromak currents and magnetic fluxes have been measured with Rogowski coils and flux loops external to the plasma. Toroidal plasma currents up to 350 kA and spheromak configuration lifetimes over 1.0 msec have been achieved at moderate power levels. The plasma formation in the S-1 Spheromak device is based on an inductive transfer of poloidal and toroidal magnetic flux from a toroidal ''flux core'' to the plasma. Formation is programmed to guide the configuration into a force-free, minimum-energy Taylor state. Properly detailed programming of the formation process is found not to be essential since plasmas adjust themselves during formation to a final equilibrium near the Taylor state. After formation, if the plasma evolves away from the stable state, then distinct relaxation oscillation events occur which restore the configuration to that stable state. The relaxation process involves reconnection of magnetic field lines, and conversion of poloidal to toroidal magnetic flux (and vice versa) has been observed and documented. The scaling of toroidal plasma current and toroidal magnetic flux in the plasma with externally applied currents is consistent with the establishment of a Taylor state after formation. In addition, the magnetic helicity is proportional to that injected from the flux core, independent of how that helicity is generated

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

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

International Nuclear Information System (INIS)

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

1999-01-01

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

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...

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)

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

Energy Technology Data Exchange (ETDEWEB)

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

2008-09-15

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

High-resolution Monthly Satellite Precipitation Product over the Conterminous United States

Science.gov (United States)

Hashemi, H.; Fayne, J.; Knight, R. J.; Lakshmi, V.

2017-12-01

We present a data set that enhanced the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) monthly product 3B43 in its accuracy and spatial resolution. For this, we developed a correction function to improve the accuracy of TRMM 3B43, spatial resolution of 25 km, by estimating and removing the bias in the satellite data using a ground-based precipitation data set. We observed a strong relationship between the bias and land surface elevation; TRMM 3B43 tends to underestimate the ground-based product at elevations above 1500 m above mean sea level (m.amsl) over the conterminous United States. A relationship was developed between satellite bias and elevation. We then resampled TRMM 3B43 to the Digital Elevation Model (DEM) data set at a spatial resolution of 30 arc second ( 1 km on the ground). The produced high-resolution satellite-based data set was corrected using the developed correction function based on the bias-elevation relationship. Assuming that each rain gauge represents an area of 1 km2, we verified our product against 9,200 rain gauges across the conterminous United States. The new product was compared with the gauges, which have 50, 60, 70, 80, 90, and 100% temporal coverage within the TRMM period of 1998 to 2015. Comparisons between the high-resolution corrected satellite-based data and gauges showed an excellent agreement. The new product captured more detail in the changes in precipitation over the mountainous region than the original TRMM 3B43.

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

Describing excited state relaxation and localization in TiO2 nanoparticles using TD-DFT

International Nuclear Information System (INIS)

Berardo, Enrico; Hu, Han-Shi; Van Dam, Hubertus J. J.; Shevlin, Stephen A.; Woodley, Scott M.; Kowalski, Karol; Zwijnenburg, Martijn A.

2014-01-01

We have investigated the description of excited state relaxation in naked and hydrated TiO 2 nanoparticles using Time-Dependent Density Functional Theory (TD-DFT) with three common hybrid exchange-correlation (XC) potentials; B3LYP, CAM-B3LYP and BHLYP. Use of TD-CAM-B3LYP and TD-BHLYP yields qualitatively similar results for all structures, which are also consistent with predictions of coupled cluster theory for small particles. TD-B3LYP, in contrast, is found to make rather different predictions; including apparent conical intersections for certain particles that are not observed with TD-CAM-B3LYP nor with TD-BHLYP. In line with our previous observations for vertical excitations, the issue with TD-B3LYP appears to be the inherent tendency of TD-B3LYP, and other XC potentials with no or a low percentage of Hartree-Fock Like Exchange, to spuriously stabilize the energy of charge-transfer (CT) states. Even in the case of hydrated particles, for which vertical excitations are generally well described with all XC potentials, the use of TD-B3LYP appears to result in CT-problems for certain particles. We hypothesize that the spurious stabilization of CT-states by TD-B3LYP even may drive the excited state optimizations to different excited state geometries than those obtained using TD-CAM-B3LYP or TD-BHLYP. In conclusion, focusing on the TD-CAM-B3LYP and TD-BHLYP results, excited state relaxation in naked and hydrated TiO 2 nanoparticles is predicted to be associated with a large Stokes' shift

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

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.

Identification of weak autoionizing resonances observed through fluorescence from the satellite states of Ar+

International Nuclear Information System (INIS)

McLaughlin, K.W.; Yenen, O.; Samson, J.A.R.

1997-01-01

Photoionization accompanied by excitation of the residual ionic state violates an independent electron model since, according to QED, photons interact only with individual electrons. By allowing measurements at a threshold event with high resolution, the observation of the fluorescence from the decay of these excited states (satellite states) is a sensitive method in the study of electron-electron interactions, providing complementary information to photoelectron spectroscopy. In the measurements reported here, an atomic beam of argon has been photoionized with 34 to 39 eV synchrotron radiation at beamline 9.0.1 of the Advanced Light Source. This energy range encompasses the 3p 4 [ 3 P] 4p 4 P, 2 P, and 2 D as well as the [ 1 D]4p 2 F satellite states of Ar + . By observing the fine-structure resolved fluorescence from these satellite states, new Rydberg series and extensions of previously known series have been resolved with an energy resolution of 3 meV. With the high photon flux available from the high resolution monochromator of beamline 9.0.1, even the weakly excited [ 3 P] 4p ( 2 S) ns,d autoionizing structure has been observed for the first time

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.

Enhancement of relaxation rates in the normal state of superconductor PuRhGa5:NQR relaxation study

International Nuclear Information System (INIS)

Sakai, H.; Kambe, S.; Tokunaga, Y.; Fujimoto, T.; Walstedt, R.E.; Yasuoka, H.; Aoki, D.; Homma, Y.; Yamamoto, E.; Nakamura, A.; Shiokawa, Y.; Nakajima, K.; Arai, Y.; Matsuda, T.D.; Haga, Y.; Onuki, Y.

2007-01-01

The spin-lattice relaxation rates (1/T 1 ) have been measured under zero field using nuclear quadrupole resonance (NQR) lines in superconductor PuRhGa 5 and Pauli-paramagnet LuCoGa 5 . In the reference LuCoGa 5 with fully-occupied 4f shell, the 1/T 1 shows the constant behavior of (T 1 T) -1 =0.495+/-0.002(sK) -1 . On the other hand, in PuRhGa 5 , 1/T 1 is much larger than in LuCoGa 5 and the 1/T 1 ∝T behavior below ∼30K is seen, where its (T 1 T) -1 value is 3.27+/-0.005(sK) -1 . These results suggest a development of coherent Fermi liquid state incorporated with 5f electrons below ∼30K in PuRhGa 5

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.

Singlet ground-state fluctuations in praseodymium observed by muon spin relaxation in PrP and PrP0.9

International Nuclear Information System (INIS)

Noakes, D R; Waeppling, R; Kalvius, G M; Jr, M F White; Stronach, C E

2005-01-01

Muon spin relaxation (μSR) in the singlet ground-state compounds PrP and PrP 0.9 reveals the unusual situation of a Lorentzian local field distribution with fast-fluctuation-limit strong-collision dynamics, a case that does not show motional narrowing. Contrary to publications by others, where PrP 0.9 was asserted to have vacancy-induced spin-glass freezing, no spin-glass freezing is seen in PrP 0.9 or PrP down to ≤100mK. This was confirmed by magnetization measurements on these same samples. In both compounds, the muon spin relaxation rate does increase as temperature decreases, demonstrating increasing strength of the paramagnetic response. A Monte Carlo model of fluctuations of Pr ions out of their crystalline-electric-field singlet ground states into their magnetic excited states (and back down again) produces the strong-collision-dynamic Lorentzian relaxation functions observed at each individual temperature but not the observed temperature dependence. This model contains no exchange interaction, and so predicts decreasing paramagnetic response as the temperature decreases, contrary to the temperature dependence observed. Comparison of the simulations to the data suggests that the exchange interaction is causing the system to approach magnetic freezing (by mode softening), but fails to complete the process

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)

Calculation of charge-state ratios for satellite Tor I

Science.gov (United States)

Summers, D.; Siscoe, G. L.

1985-01-01

The diffusion of ions in a satellite plasma torus is presently modeled in terms of a one-dimensional random walk in which the particle source is at 0, the particle sink is at an N value that is an integer greater than 2, and the scale size of the diffusion cell is unity. The probability distribution function of the number of steps to exit for an ion is obtained and used in a model which incorporates ionization by electron impact to derive steady state expressions for the ratio of doubly to singly ionized ions, as well as the total number of ions in the torus. The results thus obtained are applied to the torus of the Jovian satellite Io, in order to predict mean residence times for sulfur and oxygen ions.

DEVICE FOR MEASURMENT OF RELAXATION TIME OF THE BLEACHED STATE OF OPTICAL MATERIALS BY THE «PUMP-PROBE» METHOD IN SUB-ΜS TIME DOMAIN

Directory of Open Access Journals (Sweden)

I. V. Glazunov

2016-01-01

Full Text Available The use of passive shutters to control the duration of the light pulses is an important aspect in the miniature and microchip lasers. One of the key spectroscopic characteristics which determine the properties of the material, which can be used as a passive shutter is relaxation time of its bleached state.We describe a device for determination of relaxation time of the bleached state in optical materials by the «pump-probe» method in the sub-μs time domain. This device allows one to determine relaxation times for materials which absorb at the light wavelength of 1.5 μm, e.g., materials doped with cobalt ions Co2+. The results of test examinations of the device are described, and the relaxation time of the bleached state of Co2+ ions is measured for a novel material – transparent glass-ceramics with Co2+:Ga2 O3 nanophase – amounting to 190 ± 6 ns. 

Ultrafast excited-state relaxation of a binuclear Ag(i) phosphine complex in gas phase and solution.

Science.gov (United States)

Kruppa, S V; Bäppler, F; Klopper, W; Walg, S P; Thiel, W R; Diller, R; Riehn, C

2017-08-30

The binuclear complex [Ag 2 (dcpm) 2 ](PF 6 ) 2 (dcpm = bis(dicyclohexylphosphino)methane) exhibits a structure with a close silver-silver contact mediated by the bridging ligand and thus a weak argentophilic interaction. Upon electronic excitation this cooperative effect is strongly increased and determines the optical and luminescence properties of the compound. We have studied here the ultrafast electronic dynamics in parallel in gas phase by transient photodissociation and in solution by transient absorption. In particular, we report the diverse photofragmentation pathways of isolated [Ag 2 (dcpm) 2 ] 2+ in an ion trap and its gas phase UV photodissociation spectrum. By pump-probe fragmentation action spectroscopy (λ ex = 260 nm) in the gas phase, we have obtained fragment-specific transients which exhibit a common ultrafast multiexponential decay. This is fitted to four time constants (0.6/5.8/100/>1000 ps), highlighting complex intrinsic photophysical processes. Remarkably, multiexponential dynamics (0.9/8.5/73/604 ps) are as well found for the relaxation dynamics in acetonitrile solution. Ab initio calculations at the level of approximate coupled-cluster singles-doubles (CC2) theory of ground and electronically excited states of the reduced model system [Ag 2 (dmpm) 2 ] 2+ (dmpm = bis(dimethylphosphino)methane) indicate a shortening of the Ag-Ag distance upon excitation by 0.3-0.4 Å. In C 2 geometry two close-lying singlet states S 1 ( 1 MC(dσ*-pπ), 1 B, 4.13 eV) and S 2 ( 1 MC(dσ*-pσ), 1 A, 4.45 eV) are found. The nearly dark S 1 state has not been reported so far. The excitation of the S 2 state carries a large oscillator strength for the calculated vertical transition (266 nm). Two related triplets are calculated at T 1 (3.87 eV) and T 2 (3.90 eV). From these findings we suggest possible relaxation pathways with the two short time constants ascribed to ISC/IVR and propose from the obtained similar values in gas phase that the fast solution dynamics

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.)

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

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

Science.gov (United States)

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

2013-08-16

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

Present state of the controversy about the grain boundary relaxation

International Nuclear Information System (INIS)

Povolo, F.; Molinas, B.J.

1990-04-01

An analysis of the internal friction produced by grain boundary relaxation in metals, alloys and ceramics is presented. The different interpretations given in the literature to relaxation phenomena occurring at temperatures above about half the melting point which include the influence of grain boundaries and their interaction with solutes and precipitates are discussed in detail. A complete set of the experimental data disposable in this field since 1972 until today is reviewed. Finally, some recent experiments are discussed and new ones are suggested. They might solve the actual controversy about the real origin of the relaxation phenomena observed. If this is the case, a considerable amount of information already published can be taken into account with a good degree of confidence. This information contributes to the description of the structure and behaviour of grain boundaries, both being important topics for materials science. (author). 119 refs, 21 figs, 1 tab

Lattice sites, charge states and spin–lattice relaxation of Fe ions in "5"7Mn"+ implanted GaN and AlN

International Nuclear Information System (INIS)

Masenda, H.; Naidoo, D.; Bharuth-Ram, K.; Gunnlaugsson, H.P.; Johnston, K.; Mantovan, R.; Mølholt, T.E.; Ncube, M.; Shayestehaminzadeh, S.; Gíslason, H.P.; Langouche, G.; Ólafsson, S.; Weyer, G.

2016-01-01

The lattice sites, valence states, resulting magnetic behaviour and spin–lattice relaxation of Fe ions in GaN and AlN were investigated by emission Mössbauer spectroscopy following the implantation of radioactive "5"7Mn"+ ions at ISOLDE/CERN. Angle dependent measurements performed at room temperature on the 14.4 keV γ-rays from the "5"7Fe Mössbauer state (populated from the "5"7Mn β"− decay) reveal that the majority of the Fe ions are in the 2+ valence state nearly substituting the Ga and Al cations, and/or associated with vacancy type defects. Emission Mössbauer spectroscopy experiments conducted over a temperature range of 100–800 K show the presence of magnetically split sextets in the “wings” of the spectra for both materials. The temperature dependence of the sextets relates these spectral features to paramagnetic Fe"3"+ with rather slow spin–lattice relaxation rates which follow a T"2 temperature dependence characteristic of a two-phonon Raman process. - Highlights: • The majority of the Fe ions are in the 2+ state, located on near substitutional sites associated with vacancy type defects. • A significant fraction of the Fe ions are in the paramagnetic Fe"3"+ state. • Spin–lattice relaxation of Fe"3"+ in both GaN and AlN follows a two-phonon Raman process.

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...

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.

Highest-order optical phonon-mediated relaxation in CdTe/ZnTe quantum dots

International Nuclear Information System (INIS)

Masumoto, Yasuaki; Nomura, Mitsuhiro; Okuno, Tsuyoshi; Terai, Yoshikazu; Kuroda, Shinji; Takita, K.

2003-01-01

The highest 19th-order longitudinal optical (LO) phonon-mediated relaxation was observed in photoluminescence excitation spectra of CdTe self-assembled quantum dots grown in ZnTe. Hot excitons photoexcited highly in the ZnTe barrier layer are relaxed into the wetting-layer state by emitting multiple LO phonons of the barrier layer successively. Below the wetting-layer state, the LO phonons involved in the relaxation are transformed to those of interfacial Zn x Cd 1-x Te surrounding CdTe quantum dots. The ZnTe-like and CdTe-like LO phonons of Zn x Cd 1-x Te and lastly acoustic phonons are emitted in the relaxation into the CdTe dots. The observed main relaxation is the fast relaxation directly into CdTe quantum dots and is not the relaxation through either the wetting-layer quantum well or the band bottom of the ZnTe barrier layer. This observation shows very efficient optical phonon-mediated relaxation of hot excitons excited highly in the ZnTe conduction band through not only the ZnTe extended state but also localized state in the CdTe quantum dots reflecting strong exciton-LO phonon interaction of telluride compounds

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

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

Refraction of Radio Waves on the Radio-Occultation Satellite-to-Satellite Paths as a Characteristic of the Atmospheric State

Science.gov (United States)

Matyugov, S. S.; Yakovlev, O. I.; Pavelyev, A. G.; Pavelyev, A. A.; Anufriev, V. A.

2017-10-01

We present the results of analyzing the radio-wave refractive characteristics measured on the radio-occultation paths between the GPS navigation satellites and the FORMOSAT-3 research satellites in the central region of the European territory of Russia in 2007-2013. The diurnal, seasonal, and annual variations in the refraction angle at altitudes of 2 to 25 km are discussed. It is shown that the refraction angle can be used as an independent characteristic of the atmospheric state and its long-term variation trends. Diurnal and nocturnal variations in the refraction angle in the winter and summer seasons are analyzed. Trends in the atmospheric refraction variations over seven years are discussed.

Solvent control of charge transfer excited state relaxation pathways in [Fe(2,2 '-bipyridine)(CN)4]2-

DEFF Research Database (Denmark)

Kjær, Kasper Skov; Kunnus, Kristjan; Harlang, Tobias C. B.

2018-01-01

The excited state dynamics of solvated [Fe(bpy)(CN)4]2-, where bpy = 2,2'-bipyridine, show significant sensitivity to the solvent Lewis acidity. Using a combination of optical absorption and X-ray emission transient spectroscopies, we have previously shown that the metal to ligand charge transfer...... the MLCT excited state relaxation dynamics of [Fe(bpy)(CN)4]2- in water, a strong Lewis acid solvent. The charge-transfer excited state is now found to decay in less than 100 femtoseconds, forming a quasi-stable metal centered excited state with a 13 picosecond lifetime. We find that this MC excited state...... developed for solar applications....

[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.

On the doubly ionized states of Ar2 and their intra- and interatomic decay to Ar23+

International Nuclear Information System (INIS)

Stoychev, Spas D.; Kuleff, Alexander I.; Tarantelli, Francesco; Cederbaum, Lorenz S.

2008-01-01

Potential energy curves of the Auger state Ar + (2p -1 )-Ar, the different one- and two-site dicationic states Ar 2 ++ (with energies in the range of 32-77 eV), and the lowest two-site tricationic states Ar ++ -Ar + (with energies in the range of 64-76 eV) computed using elaborated ab initio methods are reported. The accessible relaxation channels of the electronic states of Ar ++ -Ar populated by Auger decay are studied. In particular, we study in detail the interatomic Coulombic decay following the population of one-site satellite states of Ar ++ (3s -1 3p -1 )-Ar recently observed experimentally. Other relaxation pathways of Ar ++ -Ar, including radiative charge transfer, nuclear dynamics through curve crossing, and intra-atomic decay processes are also investigated

"Using Satellite Remote Sensing to Derive Numeric Criteria in Coastal and Inland Waters of the United States"

Science.gov (United States)

Crawford, T. N.; Schaeffer, B. A.

2016-12-01

Anthropogenic nutrient pollution is a major stressor of aquatic ecosystems around the world. In the United States, states and tribes can adopt numeric water quality values (i.e. criteria) into their water quality management standards to protect aquatic life from eutrophication impacts. However, budget and resource constraints have limited the ability of many states and tribes to collect the water quality monitoring data needed to derive numeric criteria. Over the last few decades, satellite technology has provided water quality measurements on a global scale over long time periods. Water quality managers are finding the data provided by satellite technology useful in managing eutrophication impacts in coastal waters, estuaries, lakes, and reservoirs. In recent years EPA has worked with states and tribes to derive remotely sensed numeric Chl-a criteria for coastal waters with limited field-based data. This approach is now being expanded and used to derive Chl-a criteria in freshwater systems across the United States. This presentation will cover EPA's approach to derive numeric Chl-a criteria using satellite remote sensing, recommendations to improve satellite sensors to expand applications, potential areas of interest, and the challenges of using remote sensing to establish water quality management goals, as well as provide a case in which this approach has been applied.

Observation of relaxation on time scale of core hole decay by coincidence photoelectron spectroscopy

International Nuclear Information System (INIS)

Ohno, Masahide

2007-01-01

It is shown by a many-body theory that when the relaxation time of a metastable core hole state(s) to the most stable one is comparable to or shorter than core hole decay time of the former state(s), a comparison between the singles (noncoincidence) photoelectron spectroscopy (PES) spectrum and the coincidence one provides a direct evidence of the relaxation. In principle the variation with photoelectron kinetic energy of relaxation (or charge transfer (CT)) time can be determined. By singles measurement the correlation of a photoelectron generated by creation of the metastable states not only with an Auger electron generated by annihilation of the same core hole state but also with an Auger electron generated by annihilation of the stable state via relaxation of the metastable state, is completely lost, unless only the metastable state is observed by PES, whereas the correlation often manifests directly in the coincidence spectra. Thus, compared to the coincidence spectroscopy the singles one is often much less capable of elucidating the competition between relaxation and core hole decay of a metastable state. Such examples are discussed

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 steady states and relaxation oscillations in a two-phase fluid under shear flow: Experiments and phenomenological model

Science.gov (United States)

Courbin, L.; Benayad, A.; Panizza, P.

2006-01-01

By means of several rheophysics techniques, we report on an extensive study of the couplings between flow and microstructures in a two-phase fluid made of lamellar (Lα) and sponge (L3) phases. Depending on the nature of the imposed dynamical parameter (stress or shear rate) and on the experimental conditions (brine salinity or temperature), we observe several different structural steady states consisting of either multilamellar droplets (with or without a long range order) or elongated (L3) phase domains. Two different astonishing phenomena, shear-induced phase inversion and relaxation oscillations, are observed. We show that (i) phase inversion is related to a shear-induced topological change between monodisperse multilamellar droplets and elongated structures and (ii) droplet size relaxation oscillations result from a shear-induced change of the surface tension between both coexisting (Lα) and (L3) phases. To explain these relaxation oscillations, we present a phenomenological model and compare its numerical predictions to our experimental results.

Lattice sites, charge states and spin–lattice relaxation of Fe ions in {sup 57}Mn{sup +} implanted GaN and AlN

Energy Technology Data Exchange (ETDEWEB)

Masenda, H., E-mail: hilary.masenda@wits.ac.za [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Naidoo, D. [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Bharuth-Ram, K. [Physics Department, Durban University of Technology, Durban 4000 (South Africa); iThemba LABS, PO Box 725, Somerset West 7129 (South Africa); Gunnlaugsson, H.P. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); KU Leuven, Instituut voor Kern-en Stralingsfysica, 3001 Leuven (Belgium); Johnston, K. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); Mantovan, R. [Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20864 Agrate Brianza (MB) (Italy); Mølholt, T.E. [PH Department, ISOLDE/CERN, 1211 Geneva 23 (Switzerland); Ncube, M. [School of Physics, University of the Witwatersrand, Johannesburg 2050 (South Africa); Shayestehaminzadeh, S. [Materials Chemistry, RWTH Aachen University, Kopernikusstr. 10, 5274 Aachen (Germany); Gíslason, H.P. [Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík (Iceland); Langouche, G. [KU Leuven, Instituut voor Kern-en Stralingsfysica, 3001 Leuven (Belgium); Ólafsson, S. [Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík (Iceland); Weyer, G. [Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus (Denmark)

2016-03-01

The lattice sites, valence states, resulting magnetic behaviour and spin–lattice relaxation of Fe ions in GaN and AlN were investigated by emission Mössbauer spectroscopy following the implantation of radioactive {sup 57}Mn{sup +} ions at ISOLDE/CERN. Angle dependent measurements performed at room temperature on the 14.4 keV γ-rays from the {sup 57}Fe Mössbauer state (populated from the {sup 57}Mn β{sup −} decay) reveal that the majority of the Fe ions are in the 2+ valence state nearly substituting the Ga and Al cations, and/or associated with vacancy type defects. Emission Mössbauer spectroscopy experiments conducted over a temperature range of 100–800 K show the presence of magnetically split sextets in the “wings” of the spectra for both materials. The temperature dependence of the sextets relates these spectral features to paramagnetic Fe{sup 3+} with rather slow spin–lattice relaxation rates which follow a T{sup 2} temperature dependence characteristic of a two-phonon Raman process. - Highlights: • The majority of the Fe ions are in the 2+ state, located on near substitutional sites associated with vacancy type defects. • A significant fraction of the Fe ions are in the paramagnetic Fe{sup 3+} state. • Spin–lattice relaxation of Fe{sup 3+} in both GaN and AlN follows a two-phonon Raman process.

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.

Identification of weak autoionizing resonances observed through fluorescence from the satellite states of Ar{sup +}

Energy Technology Data Exchange (ETDEWEB)

McLaughlin, K.W.; Yenen, O.; Samson, J.A.R. [Univ. of Nebraska, Lincoln, NE (United States)] [and others

1997-04-01

Photoionization accompanied by excitation of the residual ionic state violates an independent electron model since, according to QED, photons interact only with individual electrons. By allowing measurements at a threshold event with high resolution, the observation of the fluorescence from the decay of these excited states (satellite states) is a sensitive method in the study of electron-electron interactions, providing complementary information to photoelectron spectroscopy. In the measurements reported here, an atomic beam of argon has been photoionized with 34 to 39 eV synchrotron radiation at beamline 9.0.1 of the Advanced Light Source. This energy range encompasses the 3p{sup 4} [{sup 3}P] 4p {sup 4}P, {sup 2}P, and {sup 2}D as well as the [{sup 1}D]4p {sup 2}F satellite states of Ar{sup +}. By observing the fine-structure resolved fluorescence from these satellite states, new Rydberg series and extensions of previously known series have been resolved with an energy resolution of 3 meV. With the high photon flux available from the high resolution monochromator of beamline 9.0.1, even the weakly excited [{sup 3}P] 4p ({sup 2}S) ns,d autoionizing structure has been observed for the first time.

Ultra-fast relaxation, decoherence, and localization of photoexcited states in π-conjugated polymers

Science.gov (United States)

Mannouch, Jonathan R.; Barford, William; Al-Assam, Sarah

2018-01-01

The exciton relaxation dynamics of photoexcited electronic states in poly(p-phenylenevinylene) are theoretically investigated within a coarse-grained model, in which both the exciton and nuclear degrees of freedom are treated quantum mechanically. The Frenkel-Holstein Hamiltonian is used to describe the strong exciton-phonon coupling present in the system, while external damping of the internal nuclear degrees of freedom is accounted for by a Lindblad master equation. Numerically, the dynamics are computed using the time evolving block decimation and quantum jump trajectory techniques. The values of the model parameters physically relevant to polymer systems naturally lead to a separation of time scales, with the ultra-fast dynamics corresponding to energy transfer from the exciton to the internal phonon modes (i.e., the C-C bond oscillations), while the longer time dynamics correspond to damping of these phonon modes by the external dissipation. Associated with these time scales, we investigate the following processes that are indicative of the system relaxing onto the emissive chromophores of the polymer: (1) Exciton-polaron formation occurs on an ultra-fast time scale, with the associated exciton-phonon correlations present within half a vibrational time period of the C-C bond oscillations. (2) Exciton decoherence is driven by the decay in the vibrational overlaps associated with exciton-polaron formation, occurring on the same time scale. (3) Exciton density localization is driven by the external dissipation, arising from "wavefunction collapse" occurring as a result of the system-environment interactions. Finally, we show how fluorescence anisotropy measurements can be used to investigate the exciton decoherence process during the relaxation dynamics.

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

Ionization yield and absorption spectra reveal superexcited Rydberg state relaxation processes in H{sub 2}O and D{sub 2}O

Energy Technology Data Exchange (ETDEWEB)

Fillion, J-H [LERMA, CNRS-UMR 8112, Observatoire de Paris-Meudon, 5 place J Janssen, F-92195, Meudon (France); Dulieu, F [LERMA, CNRS-UMR 8112, Observatoire de Paris-Meudon, 5 place J Janssen, F-92195, Meudon (France); Baouche, S [LERMA, CNRS-UMR 8112, Observatoire de Paris-Meudon, 5 place J Janssen, F-92195, Meudon (France); Lemaire, J-L [LERMA, CNRS-UMR 8112, Observatoire de Paris-Meudon, 5 place J Janssen, F-92195, Meudon (France); Jochims, H W [Institut fuer Physikalische und Theoretische Chemie der Freien Universitaet Berlin, Takustrasse 3, D-14195 Berlin 33 (Germany); Leach, S [LERMA, CNRS-UMR 8112, Observatoire de Paris-Meudon, 5 place J Janssen, F-92195, Meudon (France)

2003-07-14

The absorption cross section and the ionization quantum yield of H{sub 2}O have been measured using a synchrotron radiation source between 9 and 22 eV. Comparison between the two curves highlights competition between relaxation processes for Rydberg states converging to the first A-tilde {sup 2}A{sub 1} and to the second B-tilde {sup 2}B{sub 2} excited states of H{sub 2}O{sup +}. Comparison with D{sub 2}O absorption and ionization yields, derived from Katayama et al (1973 J. Chem. Phys. 59 4309), reveals specific energy-dependent deuteration effects on competitive predissociation and autoionization relaxation channels. Direct ionization was found to be only slightly affected by deuteration.

Visible-Light-Mediated Excited State Relaxation in Semi-Synthetic Genetic Alphabet: d5SICS and dNaM.

Science.gov (United States)

Bhattacharyya, Kalishankar; Datta, Ayan

2017-08-25

The excited state dynamics of an unnatural base pair (UBP) d5SICS/dNaM were investigated by accurate ab-initio calculations. Time-dependent density functional and high-level multireference calculations (MS-CASPT2) were performed to elucidate the excitation of this UBP and its excited state relaxation mechanism. After excitation to the bright state S 2 (ππ*), it decays to the S 1 state and then undergoes efficient intersystem crossing to the triplet manifold. The presence of sulfur atom in d5SICS leads to strong spin-orbit coupling (SOC) and a small energy gap that facilitates intersystem crossing from S 1 (n s π*) to T 2 (ππ*) followed by internal conversion to T 1 state. Similarly in dNaM, the deactivation pathway follows analogous trends. CASPT2 calculations suggest that the S 1 (ππ*) state is a dark state below the accessible S 2 (ππ*) bright state. During the ultrafast deactivation, it exhibits bond length inversion. From S 1 state, significant SOC leads the population transfer to T 3 due to a smaller energy gap. Henceforth, fast internal conversion occurs from T 3 to T 2 followed by T 1 . From time-dependent trajectory surface hopping dynamics, it is found that excited state relaxation occurs on a sub-picosecond timescale in d5SICS and dNaM. Our findings strongly suggest that there is enough energy available in triplet state of UBP to generate reactive oxygen species and induce phototoxicity with respect to cellular DNA. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

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

Relaxation in the XX quantum chain

International Nuclear Information System (INIS)

Platini, Thierry; Karevski, Dragi

2007-01-01

We present the results obtained on the magnetization relaxation properties of an XX quantum chain in a transverse magnetic field. We first consider an initial thermal kink-like state where half of the chain is initially thermalized at a very high temperature T b while the remaining half, called the system, is put at a lower temperature T s . From this initial state, we derive analytically the Green function associated with the dynamical behaviour of the transverse magnetization. Depending on the strength of the magnetic field and on the temperature of the system, different regimes are obtained for the magnetic relaxation. In particular, with an initial droplet-like state, that is a cold subsystem of the finite size in contact at both ends with an infinite temperature environment, we derive analytically the behaviour of the time-dependent system magnetization

Evaluation technology of radiation resistant materials in nuclear power plant and satellite

International Nuclear Information System (INIS)

Kang, P. H.; Kim, K. Y.; Lee, C.; Jeong, S. H.; Kim, J. A.

2007-06-01

The developed evaluation method using dielectric relaxation characteristic is measuring the increment of dipoles and mobile ions inside PEEK with deterioration, and calculate the dielectric relaxation intensity. Dielectric relaxation intensity were evaluated using Cole-Cole's circular arcs from the multi-frequencies measurements around glass transition temperature. The other proposed method using mechanical relaxation characteristic is measuring the brittleness of the deteriorated PEEK, non-destructively. The values of dielectric relaxation intensity showed the deterioration levels of each aged PEEK. Similarly, mechanical relaxation intensity showed decreasing tendency as increasing ageing time, but it did not show a certain tendency for the multi-aged PEEK. The novel developed evaluation method using dielectric relaxation characteristic will be applicable to classification of EQ, and contribute to the reliability of the lifetime extension in the NPP. These results establish a test method for both TID (Total Ionizing Dose) and SEEs through the evaluation, test, design technology. The results turned out to be quite successful, and these can be applied for parts localization for the nuclear power plant and the satellite

Joint Polar Satellite System: the United States New Generation Civilian Polar Orbiting Environmental Satellite System

Science.gov (United States)

Mandt, G.

2017-12-01

The Joint Polar Satellite System (JPSS) is the Nation's advanced series of polar-orbiting environmental satellites. JPSS represents significant technological and scientific advancements in observations used for severe weather prediction and environmental monitoring. The Suomi National Polar-orbiting Partnership (S-NPP) is providing state-of-the art atmospheric, oceanographic, and environmental data, as the first of the JPSS satellites while the second in the series, J-1, is scheduled to launch in October 2017. The JPSS baseline consists of a suite of four instruments: an advanced microwave and infrared sounders which are critical for weather forecasting; a leading-edge visible and infrared imager critical to data sparse areas such as Alaska and needed for environmental assessments such as snow/ice cover, droughts, volcanic ash, forest fires and surface temperature; and an ozone sensor primarily used for global monitoring of ozone and input to weather and climate models. The same suite of instruments that are on JPSS-1 will be on JPSS-2, 3 and 4. The JPSS-2 instruments are well into their assembly and test phases and are scheduled to be completed in 2018. The JPSS-2 spacecraft critical design review (CDR) is scheduled for 2Q 2018 with the launch in 2021. The sensors for the JPSS-3 and 4 spacecraft have been approved to enter into their acquisition phases. JPSS partnership with the US National Aeronautics and Space Agency (NASA) continues to provide a strong foundation for the program's success. JPSS also continues to maintain its important international relationships with European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) and the Japan Aerospace Exploration Agency (JAXA). JPSS works closely with its user community through the Proving Ground and Risk Reduction (PGRR) Program to identify opportunities to maximize the operational application of current JPSS capabilities. The PGRR Program also helps identify and evaluate the use of JPSS

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

Science.gov (United States)

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

2017-08-01

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

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

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

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

Global magnetic fluctuations in S-1 spheromak plasmas and relaxation toward a minimum-energy state

International Nuclear Information System (INIS)

Janos, A.; Hart, G.W.; Yamada, M.

1986-01-01

Globally coherent modes have been observed during formation in the S-1 Spheromak plasma. These modes play an important role in flux conversion and plasma relaxation toward a minimum-energy state. A significant finding is the temporal progression through the n = 5, 4, 3, 2; m = 1 mode sequence as q rises through rational fractions m/n. Peak amplitudes of the modes relative to the unperturbed field are typically less than 5%, while amplitudes as high as 20% have been observed

Effect of Au{sup 8+} irradiation on Ni/n-GaP Schottky diode: Its influence on interface state density and relaxation time

Energy Technology Data Exchange (ETDEWEB)

Shiwakoti, N.; Bobby, A. [Department of Applied Physics, Indian Institute of Technology (ISM) Dhanbad, Jharkhand 826004 (India); Asokan, K. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, New Delhi 110067 (India); Antony, Bobby, E-mail: bka.ism@gmail.com [Department of Applied Physics, Indian Institute of Technology (ISM) Dhanbad, Jharkhand 826004 (India)

2017-01-01

The in-situ capacitance-frequency and conductance-frequency measurements of 100 MeV Au{sup 8+} swift heavy ion irradiated Ni/n-GaP Schottky structure at a constant bias voltage have been carried out in the frequency range 1 kHz–1 MHz at room temperature. The interface states density and the relaxation time of the charge carriers have been calculated from Nicollian and Brews method. Various dielectric parameters such as dielectric constant, dielectric loss, loss tangent, series resistance, ac conductivity, real and imaginary parts of electric modulus have been extracted and analyzed under complex permittivity and complex electric modulus formalisms. The capacitance and conductance characteristics are found to exhibit complex behaviors at lower frequency region (1–20 kHz) for all the samples. The observed peaks and dips at low frequency region are attributed to the relaxation mechanisms of charge carriers and the interface or dipolar polarization at the interface. The dielectric properties are found to be effectively changed by the ion fluence which is attributed to the variation in interface states density and their relaxation time.

Measuring 13Cβ chemical shifts of invisible excited states in proteins by relaxation dispersion NMR spectroscopy

International Nuclear Information System (INIS)

Lundstroem, Patrik; Lin Hong; Kay, Lewis E.

2009-01-01

A labeling scheme is introduced that facilitates the measurement of accurate 13 C β chemical shifts of invisible, excited states of proteins by relaxation dispersion NMR spectroscopy. The approach makes use of protein over-expression in a strain of E. coli in which the TCA cycle enzyme succinate dehydrogenase is knocked out, leading to the production of samples with high levels of 13 C enrichment (30-40%) at C β side-chain carbon positions for 15 of the amino acids with little 13 C label at positions one bond removed (∼5%). A pair of samples are produced using [1- 13 C]-glucose/NaH 12 CO 3 or [2- 13 C]-glucose as carbon sources with isolated and enriched (>30%) 13 C β positions for 11 and 4 residues, respectively. The efficacy of the labeling procedure is established by NMR spectroscopy. The utility of such samples for measurement of 13 C β chemical shifts of invisible, excited states in exchange with visible, ground conformations is confirmed by relaxation dispersion studies of a protein-ligand binding exchange reaction in which the extracted chemical shift differences from dispersion profiles compare favorably with those obtained directly from measurements on ligand free and fully bound protein samples

Relaxation mechanism of the hydrated electron.

Science.gov (United States)

Elkins, Madeline H; Williams, Holly L; Shreve, Alexander T; Neumark, Daniel M

2013-12-20

The relaxation dynamics of the photoexcited hydrated electron have been subject to conflicting interpretations. Here, we report time-resolved photoelectron spectra of hydrated electrons in a liquid microjet with the aim of clarifying ambiguities from previous experiments. A sequence of three ultrashort laser pulses (~100 femtosecond duration) successively created hydrated electrons by charge-transfer-to-solvent excitation of dissolved anions, electronically excited these electrons via the s→p transition, and then ejected them into vacuum. Two distinct transient signals were observed. One was assigned to the initially excited p-state with a lifetime of ~75 femtoseconds, and the other, with a lifetime of ~400 femtoseconds, was attributed to s-state electrons just after internal conversion in a nonequilibrated solvent environment. These assignments support the nonadiabatic relaxation model.

Relaxation phenomena in the high temperature S-1 spheromak

International Nuclear Information System (INIS)

Ono, Y.; Ellis, R.A. Jr.; Janos, A.C.; Levinton, F.M.; Mayo, R.M.; Motley, R.W.; Ueda, Y.; Yamada, M.

1988-06-01

Operation of the S-1 device in a high current density (j/n/sub e/ ≥ 2 /times/ 10 -14 A/center dot/m) regime has created high electron temperature spheromaks (50eV ≤ T/sub e/ ≤ 130eV). The mechanisms and causes of the periodic relaxation events often observed in these hotter spheromak plasmas were made clear. Also, a relationship between the MHD relaxation cycle and confinement characteristics was revealed for the first time. Resistive loss at the outer edge of the plasma causes a departure from the initial force-free minimum-energy Taylor state to a MHD profile unstable to low-n ideal MHD modes; a relaxation event then returns the configuration to nearly a Taylor state. 11 refs., 5 figs

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.

Non-exponential dynamic relaxation in strongly nonequilibrium nonideal plasmas

International Nuclear Information System (INIS)

Morozov, I V; Norman, G E

2003-01-01

Relaxation of kinetic energy to the equilibrium state is simulated by the molecular dynamics method for nonideal two-component non-degenerate plasmas. Three limiting examples of initial states of strongly nonequilibrium plasma are considered: zero electron velocities, zero ion velocities and zero velocities of both electrons and ions. The initial non-exponential stage, its duration τ nB and subsequent exponential stages of the relaxation process are studied for a wide range of the nonideality parameter and the ion mass

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

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

International Nuclear Information System (INIS)

Liu, Yuzhu; Knopp, Gregor; Qin, Chaochao; Gerber, Thomas

2015-01-01

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S 2 to S 1 is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S 2 state to the vibrationally hot S 1 state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S 1 state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding

Relaxation and transport properties of liquid n-triacontane

International Nuclear Information System (INIS)

Kondratyuk, N D; Lankin, A V; Norman, G E; Stegailov, V V

2015-01-01

Molecular modelling is used to calculate transport properties and to study relaxation of liquid n-triacontane (C 30 H 62 ). The problem is important in connection with the behavior of liquid isolators in a pre-breakdown state. Two all-atom models and a united-atom model are used. Shear viscosity is calculated using the Green-Kubo formula. The force fields are compared with each other using the following criteria: the required time for one molecular dynamics step, the compliance of the main physical and transport properties with experimental values. The problem of the system equilibration is considered. The united-atom potential is used to model the n-triacontane liquid with an initial directional orientation. The time of relaxation to the disordered state, when all molecules orientations are randomized, are obtained. The influence of the molecules orientations on the shear viscosity value and the shear viscosity relaxation are treated. (paper)

Spectroscopy and intramolecular relaxation of methyl salicylate in its first excited singlet state

Science.gov (United States)

Kuper, Jerry W.; Perry, David S.

1984-05-01

High resolution fluorescence excitation experiments are reported for the blue emitting rotamer of methyl salicylate in its first excited singlet state. These experiments employ moderate expansions of methyl salicylate seeded in argon ( P0D=5-8 Torr cm) to achieve rotational and vibrational cooling in a pulsed supersonic jet. The rotational contour of the electronic origin at 30 055.3 cm-1 is shown to be consistent with a geometrically distorted π-π* excited state, partially polarized along the A axis and with a rotational temperature of 5-7 K. A noticeable broadening of the spectral features beyond the rotational contour begins at 500 cm-1 above the origin and then increases rapidly above 900 cm-1 reaching a width of 12 cm-1 near 1200 cm-1. The constancy of fluorescence decay lifetimes in this region indicate that intramolecular vibrational relaxation in the S1 manifold is the broadening mechanism.

Stochastic and Chaotic Relaxation Oscillations

NARCIS (Netherlands)

Grasman, J.; Roerdink, J.B.T.M.

1988-01-01

For relaxation oscillators stochastic and chaotic dynamics are investigated. The effect of random perturbations upon the period is computed. For an extended system with additional state variables chaotic behavior can be expected. As an example, the Van der Pol oscillator is changed into a

Current state of art of satellite altimetry

Science.gov (United States)

Łyszkowicz, Adam Bolesław; Bernatowicz, Anna

2017-12-01

One of the fundamental problems of modern geodesy is precise defi nition of the gravitational fi eld and its changes in time. This is essential in positioning and navigation, geophysics, geodynamics, oceanography and other sciences related to the climate and Earth's environment. One of the major sources of gravity data is satellite altimetry that provides gravity data with almost 75% surface of the Earth. Satellite altimetry also provides data to study local, regional and global geophysical processes, the geoid model in the areas of oceans and seas. This technique can be successfully used to study the ocean mean dynamic topography. The results of the investigations and possible products of altimetry will provide a good material for the GGOS (Global Geodetic Observing System) and institutions of IAS (International Altimetry Service). This paper presents the achievements in satellite altimetry in all the above disciplines obtained in the last years. First very shorly basic concept of satellite altimetry is given. In order to obtain the highest accuracy on range measurements over the ocean improved of altimetry waveforms performed on the ground is described. Next, signifi cant improvements of sea and ocean gravity anomalies models developed presently is shown. Study of sea level and its extremes examined, around European and Australian coasts using tide gauges data and satellite altimetry measurements were described. Then investigations of the phenomenon of the ocean tides, calibration of altimeters, studies of rivers and ice-sheets in the last years are given.

Current state of art of satellite altimetry

Directory of Open Access Journals (Sweden)

Łyszkowicz Adam Bolesław

2017-12-01

Full Text Available One of the fundamental problems of modern geodesy is precise defi nition of the gravitational fi eld and its changes in time. This is essential in positioning and navigation, geophysics, geodynamics, oceanography and other sciences related to the climate and Earth’s environment. One of the major sources of gravity data is satellite altimetry that provides gravity data with almost 75% surface of the Earth. Satellite altimetry also provides data to study local, regional and global geophysical processes, the geoid model in the areas of oceans and seas. This technique can be successfully used to study the ocean mean dynamic topography. The results of the investigations and possible products of altimetry will provide a good material for the GGOS (Global Geodetic Observing System and institutions of IAS (International Altimetry Service. This paper presents the achievements in satellite altimetry in all the above disciplines obtained in the last years. First very shorly basic concept of satellite altimetry is given. In order to obtain the highest accuracy on range measurements over the ocean improved of altimetry waveforms performed on the ground is described. Next, signifi cant improvements of sea and ocean gravity anomalies models developed presently is shown. Study of sea level and its extremes examined, around European and Australian coasts using tide gauges data and satellite altimetry measurements were described. Then investigations of the phenomenon of the ocean tides, calibration of altimeters, studies of rivers and ice-sheets in the last years are given.

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.

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

Anomalous relaxation in binary mixtures: a dynamic facilitation picture

International Nuclear Information System (INIS)

Moreno, A J; Colmenero, J

2007-01-01

Recent computational investigations of polymeric and non-polymeric binary mixtures have reported anomalous relaxation features when both components exhibit very different mobilities. Anomalous relaxation is characterized by sublinear power-law behaviour for mean-squared displacements, logarithmic decay in dynamic correlators, and a striking concave-to-convex crossover in the latter by tuning the relevant control parameter, in analogy with predictions of the mode-coupling theory for state points close to higher-order transitions. We present Monte Carlo simulations on a coarse-grained model for relaxation in binary mixtures. The liquid structure is substituted by a three-dimensional array of cells. A spin variable is assigned to each cell, representing unexcited and excited local states of a mobility field. Changes in local mobility (spin flip) are permitted according to kinetic constraints determined by the mobilities of the neighbouring cells. We introduce two types of cell ('fast' and 'slow') with very different rates for spin flip. This coarse-grained model qualitatively reproduces the mentioned anomalous relaxation features observed for real binary mixtures

The dependence of the ultrafast relaxation kinetics of the S2 and S1 states in β-carotene homologs and lycopene on conjugation length studied by femtosecond time-resolved absorption and Kerr-gate fluorescence spectroscopies

Science.gov (United States)

Kosumi, Daisuke; Fujiwara, Masazumi; Fujii, Ritsuko; Cogdell, Richard J.; Hashimoto, Hideki; Yoshizawa, Masayuki

2009-06-01

The ultrafast relaxation kinetics of all-trans-β-carotene homologs with varying numbers of conjugated double bonds n(n =7-15) and lycopene (n =11) has been investigated using femtosecond time-resolved absorption and Kerr-gate fluorescence spectroscopies, both carried out under identical excitation conditions. The nonradiative relaxation rates of the optically allowed S2(1Bu+1) state were precisely determined by the time-resolved fluorescence. The kinetics of the optically forbidden S1(2Ag-1) state were observed by the time-resolved absorption measurements. The dependence of the S1 relaxation rates upon the conjugation length is adequately described by application of the energy gap law. In contrast to this, the nonradiative relaxation rates of S2 have a minimum at n =9 and show a reverse energy gap law dependence for values of n above 11. This anomalous behavior of the S2 relaxation rates can be explained by the presence of an intermediate state (here called the Sx state) located between the S2 and S1 states at large values of n (such as n =11). The presence of such an intermediate state would then result in the following sequential relaxation pathway S2→Sx→S1→S0. A model based on conical intersections between the potential energy curves of these excited singlet states can readily explain the measured relationships between the decay rates and the energy gaps.

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

Tracking ultrafast relaxation dynamics of furan by femtosecond photoelectron imaging

Energy Technology Data Exchange (ETDEWEB)

Liu, Yuzhu, E-mail: yuzhu.liu@gmail.com [School of Physics and Optoelectronic Engineering, Nanjing University of Information Science and Technology, Nanjing 210044 (China); Knopp, Gregor [Paul Scherrer Institute, Villigen 5232 (Switzerland); Qin, Chaochao [Department of Physics, Henan Normal University, Xinxiang 453007 (China); Gerber, Thomas [Paul Scherrer Institute, Villigen 5232 (Switzerland)

2015-01-13

Graphical abstract: - Highlights: • Relaxation dynamics of furan are tracked by femtosecond photoelectron imaging. • The mechanism for ultrafast formation of α-carbene and β-carbene is proposed. • Ultrafast internal conversion from S{sub 2} to S{sub 1} is observed. • The transient characteristics of the fragment ions are obtained. • Single-color multi-photon ionization dynamics at 800 nm are also studied. - Abstract: Ultrafast internal conversion dynamics of furan has been studied by femtosecond photoelectron imaging (PEI) coupled with photofragmentation (PF) spectroscopy. Photoelectron imaging of single-color multi-photon ionization and two-color pump–probe ionization are obtained and analyzed. Photoelectron bands are assigned to the related states. The time evolution of the photoelectron signal by pump–probe ionization can be well described by a biexponential decay: two rapid relaxation pathways with time constants of ∼15 fs and 85 (±11) fs. The rapid relaxation is ascribed to the ultrafast internal conversion (IC) from the S{sub 2} state to the vibrationally hot S{sub 1} state. The second relaxation process is attributed to the redistributions and depopulation of secondarily populated high vibronic S{sub 1} state and the formation of α-carbene and β-carbene by H immigration. Additionally, the transient characteristics of the fragment ions are also measured and discussed as a complementary understanding.

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

Spin-orbit coupling induced two-electron relaxation in silicon donor pairs

Science.gov (United States)

Song, Yang; Das Sarma, S.

2017-09-01

We unravel theoretically a key intrinsic relaxation mechanism among the low-lying singlet and triplet donor-pair states in silicon, an important element in the fast-developing field of spintronics and quantum computation. Despite the perceived weak spin-orbit coupling (SOC) in Si, we find that our discovered relaxation mechanism, combined with the electron-phonon and interdonor interactions, drives the transitions in the two-electron states over a large range of donor coupling regimes. The scaling of the relaxation rate with interdonor exchange interaction J goes from J5 to J4 at the low to high temperature limits. Our analytical study draws on the symmetry analysis over combined band, donor envelope, and valley configurations. It uncovers naturally the dependence on the donor-alignment direction and triplet spin orientation, and especially on the dominant SOC source from donor impurities. While a magnetic field is not necessary for this relaxation, unlike in the single-donor spin relaxation, we discuss the crossover behavior with increasing Zeeman energy in order to facilitate comparison with experiments.

Effective temperature in relaxation of Coulomb glasses.

Science.gov (United States)

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

2008-08-01

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

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

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.

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

Confinement sensitivity in quantum dot singlet-triplet relaxation

Science.gov (United States)

Wesslén, C. J.; Lindroth, E.

2017-11-01

Spin-orbit mediated phonon relaxation in a two-dimensional quantum dot is investigated using different confining potentials. Elliptical harmonic oscillator and cylindrical well results are compared to each other in the case of a two-electron GaAs quantum dot subjected to a tilted magnetic field. The lowest energy set of two-body singlet and triplet states are calculated including spin-orbit and magnetic effects. These are used to calculate the phonon induced transition rate from the excited triplet to the ground state singlet for magnetic fields up to where the states cross. The roll of the cubic Dresselhaus effect, which is found to be much more important than previously assumed, and the positioning of ‘spin hot-spots’ are discussed and relaxation rates for a few different systems are exhibited.

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.

Satellite bands of the RbCs molecule in the range of highly excited states

Energy Technology Data Exchange (ETDEWEB)

Rakić, Mario; Beuc, Robert; Skenderović, Hrvoje, E-mail: hrvoje@ifs.hr [Institute of Physics, Bijenička cesta 46, Zagreb 10000 (Croatia); Bouloufa-Maafa, Nadia; Dulieu, Olivier; Vexiau, Romain [Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, Université Paris-Saclay, Bât. 505, Campus d’Orsay, Orsay Cedex 91405 (France); Pichler, Goran [Physics Department, Kuwait University, PO Box 5969, Safat—13060 (Kuwait)

2016-05-28

We report on the observation of three RbCs satellite bands in the blue and green ranges of the visible spectrum. Absorption measurements are performed using all-sapphire cell filled with a mixture of Rb and Cs. We compare high resolution absorption spectrum of Rb-Cs vapor mixture with pure Rb and Cs vapor spectra from the literature. After detailed analysis, the new satellite bands of RbCs molecule at 418.3 nm, 468.3, and 527.5 nm are identified. The origin of these bands is discussed by direct comparison with difference potentials derived from quantum chemistry calculations of RbCs potential energy curves. These bands originate from the lower Rydberg states of the RbCs molecule. This study thus provides further insight into photoassociation of lower Rydberg molecular states, approximately between Cs(7s) + Rb(5s) and Cs(6s) + Rb(6p) asymptotes, in ultracold gases.

Influence of relaxation on emission and excitation of coherent states of electromagnetic field in the Jaynes-Cummings model

International Nuclear Information System (INIS)

Verlan, E.M.

2003-01-01

A two-level atom interacting with a field mode is considered. The field frequency is assumed to be equal to the atom transition frequency. The relaxation equations of the atom - field system are written in the basis of dressed states of the Jaynes - Cummings model taking into account quasi-resonant pumping. Their solutions are derived for a stationary regime. The average amplitude of a coherent electromagnetic field is found

Local NMR relaxation rates T1-1 and T2-1 depending on the d -vector symmetry in the vortex state of chiral and helical p -wave superconductors

Science.gov (United States)

Tanaka, Kenta K.; Ichioka, Masanori; Onari, Seiichiro

2018-04-01

Local NMR relaxation rates in the vortex state of chiral and helical p -wave superconductors are investigated by the quasiclassical Eilenberger theory. We calculate the spatial and resonance frequency dependences of the local NMR spin-lattice relaxation rate T1-1 and spin-spin relaxation rate T2-1. Depending on the relation between the NMR relaxation direction and the d -vector symmetry, the local T1-1 and T2-1 in the vortex core region show different behaviors. When the NMR relaxation direction is parallel to the d -vector component, the local NMR relaxation rate is anomalously suppressed by the negative coherence effect due to the spin dependence of the odd-frequency s -wave spin-triplet Cooper pairs. The difference between the local T1-1 and T2-1 in the site-selective NMR measurement is expected to be a method to examine the d -vector symmetry of candidate materials for spin-triplet superconductors.

Polarized Raman spectroscopic study of relaxed high density amorphous ices under pressure.

Science.gov (United States)

Suzuki, Yoshiharu; Tominaga, Yasunori

2010-10-28

We have made high density amorphous ice (HDA) by the pressure-induced amorphization of hexagonal ice at 77 K and measured the volume change on isobaric heating in a pressure range between 0.1 and 1.5 GPa. The volume of HDA on heating below ∼0.35 GPa increases, while the volume of HDA on heating above ∼0.35 GPa decreases. The polarized OH-stretching Raman spectra of the relaxed HDAs are compared with that of the unannealed HDA. The relaxed HDAs are prepared at 0.2 GPa at 130 K and 1.5 GPa at 160 K. It is found that the relatively strong totally symmetric OH-stretching vibration mode around 3100 cm(-1) exists in the depolarized reduced Raman spectrum χ(VH)(") of the unannealed HDA and that its intensity rapidly decreases by relaxation. The χ(VH)(") profiles of the relaxed HDA are similar to those of liquid water. These results indicate that the HDA reaches a nearly equilibrium state by annealing and the intrinsic state of HDA relates to a liquid state. The pressure-volume curve of the relaxed HDA at 140 K seems to be smooth in the pressure range below 1.5 GPa.

On the exponential energy gap law in He--I2 vibrational relaxation

International Nuclear Information System (INIS)

Maricq, M.M.

1990-01-01

A comparison between coupled states, infinite order sudden, and classical path calculations is used to elucidate the origin of an exponential energy gap law recently observed for vibrational relaxation from highly excited states in the B 0 + u state of I 2 due to collisions with He. All three methods provide relaxation cross sections in good agreement with experiment. Anharmonic effects play an important role, with accurate results obtained with a Morse, but not harmonic, oscillator description of the I * 2 molecule. The nearly exact agreement between rotationally summed coupled states cross sections and the IOSA is consistent with the view that the I * 2 molecule does not rotate significantly during a collision. A closed form solution of the forced harmonic oscillator, valid for highly excited states, predicts a J 2 |Δv| distribution of vibrationally relaxed states at a given collision angle and impact parameter. The vibrationally close coupled-infinite order sudden (VCC-IOSA) results bear this out and show that the observed exponential scaling law arises from a superposition of such distributions over θ and b

Lineshape theory of pigment-protein complexes: How the finite relaxation time of nuclei influences the exciton relaxation-induced lifetime broadening

Energy Technology Data Exchange (ETDEWEB)

Dinh, Thanh-Chung; Renger, Thomas, E-mail: thomas.renger@jku.at [Institut für Theoretische Physik, Johannes Kepler University Linz, Altenberger Str. 69, 4040 Linz (Austria)

2016-07-21

In pigment-protein complexes, often the excited states are partially delocalized and the exciton-vibrational coupling in the basis of delocalized states contains large diagonal and small off-diagonal elements. This inequality may be used to introduce potential energy surfaces (PESs) of exciton states and to treat the inter-PES coupling in Markov and secular approximations. The resulting lineshape function consists of a Lorentzian peak that is broadened by the finite lifetime of the exciton states caused by the inter-PES coupling and a vibrational sideband that results from the mutual displacement of the excitonic PESs with respect to that of the ground state. So far analytical expressions have been derived that relate the exciton relaxation-induced lifetime broadening to the Redfield [T. Renger and R. A. Marcus, J. Chem. Phys. 116, 9997 (2002)] or modified Redfield [M. Schröder, U. Kleinekathöfer, and M. Schreiber, J. Chem. Phys. 124, 084903 (2006)] rate constants of exciton relaxation, assuming that intra-PES nuclear relaxation is fast compared to inter-PES transfer. Here, we go beyond this approximation and provide an analytical expression, termed Non-equilibrium Modified Redfield (NeMoR) theory, for the lifetime broadening that takes into account the finite nuclear relaxation time. In an application of the theory to molecular dimers, we find that, for a widely used experimental spectral density of the exciton-vibrational coupling of pigment-protein complexes, the NeMoR spectrum at low-temperatures (T < 150 K) is better approximated by Redfield than by modified Redfield theory. At room temperature, the lifetime broadening obtained with Redfield theory underestimates the NeMoR broadening, whereas modified Redfield theory overestimates it by a similar amount. A fortuitous error compensation in Redfield theory is found to explain the good performance of this theory at low temperatures. Since steady state spectra of PPCs are often measured at low temperatures

Resonant satellite transitions in argon

International Nuclear Information System (INIS)

Samson, J.A.R.; Lee Eunmee; Chung, Y.

1990-01-01

The production of specific Ar + satellite states has been studied with synchrotron radiation at wavelengths between 300 and 350 A with an effective energy resolution of 20 meV. The specific states studied were the ( 3 P)4p( 2 P 3/2 ), ( 1 D)4p( 2 F 7/2 ), and ( 1 D)4p( 2 P 1/2 ) states. The fluorescent radiation emitted from these excited ionic states was measured at 4766, 4611, and 4133 A by the use of narrow band interference filters. The variation of the fluorescence intensity was measured as a function of wavelength. This provided a measure of the relative cross section for production of the satellite states. Each satellite state was found to be completely dominated by autoionization of the neutral doubly excited states (3s 2 3p 4 )nl, n'l' found in this spectral region. (orig.)

Self-similarly evolving and minimally dissipated stable states of plasmas realized after relaxation and self-organization processes

International Nuclear Information System (INIS)

Kondoh, Yoshiomi; Hakoiwa, Toru; Okada, Akihito; Kobayashi, Naohiro; Takahashi, Toshiki

2006-01-01

A novel set of simultaneous eigenvalue equations having dissipative terms are derived to find self-similarly evolving and minimally dissipated stable states of plasmas realized after relaxation and self-organization processes. By numerically solving the set of eigenvalue equations in a cylindrical model, typical spatial profiles of plasma parameters, electric and magnetic fields and diffusion factors are presented, all of which determine self-consistently with each other by physical laws and mutual relations among them, just as in experimental plasmas. (author)

Satellite myths

Science.gov (United States)

Easton, Roger L.; Hall, David

2008-01-01

Richard Corfield's article “Sputnik's legacy” (October 2007 pp23-27) states that the satellite on board the US Vanguard rocket, which exploded during launch on 6 December 1957 two months after Sputnik's successful take-off, was “a hastily put together contraption of wires and circuitry designed only to send a radio signal back to Earth”. In fact, the Vanguard satellite was developed over a period of several years and put together carefully using the best techniques and equipment available at the time - such as transistors from Bell Laboratories/Western Electric. The satellite contained not one but two transmitters, in which the crystal-controlled oscillators had been designed to measure both the temperature of the satellite shell and of the internal package.

Relaxation peak near 200 K in NiTi alloy

Science.gov (United States)

Zhu, J. S.; Schaller, R.; Benoit, W.

1989-10-01

Internal friction (IF), frequency ( f), electrical resistance ( R) and zero point movement of the torsion pendulum (ɛ) have been measured in near equi-atomic NiTi alloy in order to clarify the mechanism for the relaxation peak near 200 K. The height of the relaxation peak decreases successively with thermal cycling and settles down to a lower stable value in running 15 cycles. However, the electrical resistance of the sample shows a variation in contrast with the internal friction. Both of them will return to the initial state after a single annealing at 773 K for 1 h. The probable mechanism of this relaxation peak was discussed.

State-specific Multi-reference Perturbation Theories with Relaxed Coefficients: Molecular Applications

Directory of Open Access Journals (Sweden)

Debashis Mukherjee

2002-06-01

Full Text Available Abstract: We present in this paper two new versions of Rayleigh-Schr¨odinger (RS and the Brillouin-Wigner (BW state-specific multi-reference perturbative theories (SSMRPT which stem from our state-specific multi-reference coupled-cluster formalism (SS-MRCC, developed with a complete active space (CAS. They are manifestly sizeextensive and are designed to avoid intruders. The combining coefficients cμ for the model functions φμ are completely relaxed and are obtained by diagonalizing an effective operator in the model space, one root of which is the target eigenvalue of interest. By invoking suitable partitioning of the hamiltonian, very convenient perturbative versions of the formalism in both the RS and the BW forms are developed for the second order energy. The unperturbed hamiltonians for these theories can be chosen to be of both Mφller-Plesset (MP and Epstein-Nesbet (EN type. However, we choose the corresponding Fock operator fμ for each model function φμ, whose diagonal elements are used to define the unperturbed hamiltonian in the MP partition. In the EN partition, we additionally include all the diagonal direct and exchange ladders. Our SS-MRPT thus utilizes a multi-partitioning strategy. Illustrative numerical applications are presented for potential energy surfaces (PES of the ground (1Σ+ and the first delta (1Δ states of CH+ which possess pronounced multi-reference character. Comparison of the results with the corresponding full CI values indicates the efficacy of our formalisms.

Quantum communication for satellite-to-ground networks with partially entangled states

International Nuclear Information System (INIS)

Chen Na; Quan Dong-Xiao; Pei Chang-Xing; Yang-Hong

2015-01-01

To realize practical wide-area quantum communication, a satellite-to-ground network with partially entangled states is developed in this paper. For efficiency and security reasons, the existing method of quantum communication in distributed wireless quantum networks with partially entangled states cannot be applied directly to the proposed quantum network. Based on this point, an efficient and secure quantum communication scheme with partially entangled states is presented. In our scheme, the source node performs teleportation only after an end-to-end entangled state has been established by entanglement swapping with partially entangled states. Thus, the security of quantum communication is guaranteed. The destination node recovers the transmitted quantum bit with the help of an auxiliary quantum bit and specially defined unitary matrices. Detailed calculations and simulation analyses show that the probability of successfully transferring a quantum bit in the presented scheme is high. In addition, the auxiliary quantum bit provides a heralded mechanism for successful communication. Based on the critical components that are presented in this article an efficient, secure, and practical wide-area quantum communication can be achieved. (paper)

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.

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)

Quantum efficiency and excited-state relaxation dynamics in neodymium-doped phosphate laser glasses

International Nuclear Information System (INIS)

Caird, J.A.; Ramponi, A.J.; Staver, P.R.

1991-01-01

Radiometrically calibrated spectroscopic techniques employing an integrating-sphere detection system have been used to determine the fluorescence quantum efficiencies for two commercially available Nd 3+ -doped phosphate laser glasses, LG-750 and LG-760. Quantum efficiencies and fluorescence lifetimes were measured for samples with various neodymium concentrations. It is shown that the effects of concentration quenching are accurately described when both resonant nonradiative excitation hopping (the Burshtein model) and annihilation by cross relaxation are accounted for by Foerster--Dexter dipole--dipole energy-transfer theory. The Foerster--Dexter critical range for nonradiative excitation hopping was found to be R DD =11 A, while the critical range for cross relaxation was close to R DA =4 A in these glasses. The quantum efficiency at low Nd 3+ concentrations was (92±5)%, implying a nonradiative relaxation rate of 210±150 s -1 for isolated ions. Improved values for the radiative lifetimes and the stimulated emission cross sections for these glasses were also deduced from the measurements

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.

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

Science.gov (United States)

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

2015-09-01

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

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

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

Energy Technology Data Exchange (ETDEWEB)

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

2007-05-23

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

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

International Nuclear Information System (INIS)

Paluch, M; Grzybowska, K; Grzybowski, A

2007-01-01

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

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.

Cooperative and cognitive satellite systems

CERN Document Server

Chatzinotas, Symeon; De Gaudenzi, Riccardo

2015-01-01

Cooperative and Cognitive Satellite Systems provides a solid overview of the current research in the field of cooperative and cognitive satellite systems, helping users understand how to incorporate state-of-the-art communication techniques in innovative satellite network architectures to enable the next generation of satellite systems. The book is edited and written by top researchers and practitioners in the field, providing a comprehensive explanation of current research that allows users to discover future technologies and their applications, integrate satellite and terrestrial systems

Relaxation and particle diffusion in the Proto S-1/C spheromak

International Nuclear Information System (INIS)

Meyerhofer, D.D.

1987-01-01

The relationship between relaxation and particle diffusion in the Proto S-1C spheromak has been studied. The plasma was formed in a magnetic configuration which was not the minimum-energy Taylor state, and went through a period of relaxation before its magnetic configuration was that of the Taylor state. Early in the relaxation phase, the internal and external magnetic fluctuations were correlated and it was found that, at the time of peak amplitude, they had a radial structure of a tearing mode. After the reconnection of these modes, the plasma continued to evolve towards the Taylor state with only small magnetic fluctuations at the center of plasma. The local particle diffusion coefficient was measured in these Proto S-1C discharges, the technique used was to inject a delta-function source of impurities into the plasma and observe the motion of the impurities relative to the flux surface. It was found that, during the decay phase of the spheromak discharge, when the plasma was in a Taylor state, the carbon diffusion coefficient was explained classically. While the plasma was relaxing towards the Taylor state, the diffusion coefficient was 2 ∼ 4a times larger than classical. At this time, the plasma was not yet force-free. This nonclassical diffusion appears to have been caused by v/sub ExB/ velocities due to correlations between the fluctuating electric field and density. Because the v/sub ExB/ velocity acts on all of the plasma species similarly, the anomalous hydrogen-particle diffusion coefficient should have been as large as that of carbon

Relaxation of cntrol of oil industries in Europe

Energy Technology Data Exchange (ETDEWEB)

Sugimura, Nobuaki [The Inst. of Energy Economics, Tokyo, (Japan)

1989-03-01

This article summarizes the results of a survey including field surveys on the actual states and trends of relaxation of the control of oil industries in EC states. In classifying EC states by the degree of the government influence over the industries of oil refining and distribution, there are the group consisting of UK, West Germany and France, etc. where no control is imposed on individual oil companies in the fields of quantity and price of oil, the group consisting of Italy, etc. where no control exists on quantity, but price is partially controlled, and the group consisting of Spain and Greece, etc. where the government controls both quantity and price at the present stage although they are pushing relaxation of such control in accordance with the terms and conditions at the time of their entry to EC. The oil policy of EC is to remove as far as possible interferences of the governments and open its oil market free. This and the trend of over supply of oil since 1980 are two major factors of relaxation of oil industries control in Europe. The author considers it desirable that the oil industries in Japan should withstand international competitions by their inventiveness, creativity and effort, and importation of oil products should be held at a supplementary degree in view of their characters. 2 refs., 1 fig., 4 tabs.

Ideal relaxation of the Hopf fibration

Science.gov (United States)

Smiet, Christopher Berg; Candelaresi, Simon; Bouwmeester, Dirk

2017-07-01

Ideal magnetohydrodynamics relaxation is the topology-conserving reconfiguration of a magnetic field into a lower energy state where the net force is zero. This is achieved by modeling the plasma as perfectly conducting viscous fluid. It is an important tool for investigating plasma equilibria and is often used to study the magnetic configurations in fusion devices and astrophysical plasmas. We study the equilibrium reached by a localized magnetic field through the topology conserving relaxation of a magnetic field based on the Hopf fibration in which magnetic field lines are closed circles that are all linked with one another. Magnetic fields with this topology have recently been shown to occur in non-ideal numerical simulations. Our results show that any localized field can only attain equilibrium if there is a finite external pressure, and that for such a field a Taylor state is unattainable. We find an equilibrium plasma configuration that is characterized by a lowered pressure in a toroidal region, with field lines lying on surfaces of constant pressure. Therefore, the field is in a Grad-Shafranov equilibrium. Localized helical magnetic fields are found when plasma is ejected from astrophysical bodies and subsequently relaxes against the background plasma, as well as on earth in plasmoids generated by, e.g., a Marshall gun. This work shows under which conditions an equilibrium can be reached and identifies a toroidal depression as the characteristic feature of such a configuration.

Mechanisms of Coupled Vibrational Relaxation and Dissociation in Carbon Dioxide.

Science.gov (United States)

Armenise, Iole; Kustova, Elena

2018-05-21

A complete vibrational state-specific kinetic scheme describing dissociating carbon dioxide mixtures is proposed. CO 2 symmetric, bending and asymmetric vibrations and dissociation-recombination are strongly coupled through inter-mode vibrational energy transfers. Comparative study of state-resolved rate coefficients is carried out; the effect of different transitions may vary considerably with temperature. A non-equilibrium 1-D boundary layer flow typical to hypersonic planetary entry is studied in the state-to-state approach. To assess the sensitivity of fluid-dynamic variables and heat transfer to various vibrational transitions and chemical reactions, corresponding processes are successively included to the kinetic scheme. It is shown that vibrational-translational (VT) transitions in the symmetric and asymmetric modes do not alter the flow and can be neglected whereas the VT 2 exchange in the bending mode is the main channel of vibrational relaxation. Inter-mode vibrational exchanges affect the flow implicitly, through energy redistribution enhancing VT relaxation; the dominating role belongs to near-resonant transitions between symmetric and bending modes as well as between CO molecules and CO 2 asymmetric mode. Strong coupling between VT 2 relaxation and chemical reactions is emphasized. While vibrational distributions and average vibrational energy show strong dependence on the kinetic scheme, the heat flux is more sensitive to chemical reactions.

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.

Vibronic relaxation in molecular mixed crystals : Pentacene in naphthalene and p-terphenyl

NARCIS (Netherlands)

Hesselink, Wim H.; Wiersma, Douwe A.

1981-01-01

Picosecond photon echo techniques are used to measure directly vibronic relaxation times in the first excited singlet state of pentacene in naphthalene and p-terphenyl. In regions of low (< 300 cm–1) and high (> 1000 cm–1) vibrational energy, relaxation is fast (τ <2 ps) due to direct phonon

Solid State Inflation Balloon Active Deorbiter: Scalable Low-Cost Deorbit System for Small Satellites

Science.gov (United States)

Huang, Adam

2016-01-01

The goal of the Solid State Inflation Balloon Active Deorbiter project is to develop and demonstrate a scalable, simple, reliable, and low-cost active deorbiting system capable of controlling the downrange point of impact for the full-range of small satellites from 1 kg to 180 kg. The key enabling technology being developed is the Solid State Gas Generator (SSGG) chip, generating pure nitrogen gas from sodium azide (NaN3) micro-crystals. Coupled with a metalized nonelastic drag balloon, the complete Solid State Inflation Balloon (SSIB) system is capable of repeated inflation/deflation cycles. The SSGG minimizes size, weight, electrical power, and cost when compared to the current state of the art.

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.

Monitoring Cyanobacteria with Satellites Webinar

Science.gov (United States)

real-world satellite applications can quantify cyanobacterial harmful algal blooms and related water quality parameters. Provisional satellite derived cyanobacteria data and different software tools are available to state environmental and health agencies.

Noise-Induced Modulation of the Relaxation Kinetics around a Non-Equilibrium Steady State of Non-Linear Chemical Reaction Networks

OpenAIRE

Ramaswamy, Rajesh; Sbalzarini, Ivo F; González-Segredo, Nélido

2011-01-01

Stochastic effects from correlated noise non-trivially modulate the kinetics of non-linear chemical reaction networks. This is especially important in systems where reactions are confined to small volumes and reactants are delivered in bursts. We characterise how the two noise sources confinement and burst modulate the relaxation kinetics of a non-linear reaction network around a non-equilibrium steady state. We find that the lifetimes of species change with burst input and confinement. Confi...

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.

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.

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

International Nuclear Information System (INIS)

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

1981-01-01

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

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

Spin dynamics of Mn12-acetate in the thermally activated tunneling regime: ac susceptibility and magnetization relaxation

Science.gov (United States)

Pohjola, Teemu; Schoeller, Herbert

2000-12-01

In this work, we study the spin dynamics of Mn12-acetate molecules in the regime of thermally assisted tunneling. In particular, we describe the system in the presence of a strong transverse magnetic field. Similar to recent experiments, the relaxation time/rate is found to display a series of resonances; their Lorentzian shape is found to stem from the tunneling. The dynamic susceptibility χ(ω) is calculated starting from the microscopic Hamiltonian and the resonant structure manifests itself also in χ(ω). Similar to recent results reported on another molecular magnet, Fe8, we find oscillations of the relaxation rate as a function of the transverse magnetic field when the field is directed along a hard axis of the molecules. This phenomenon is attributed to the interference of the geometrical or Berry phase. We propose susceptibility experiments to be carried out for strong transverse magnetic fields to study these oscillations and for a better resolution of the sharp satellite peaks in the relaxation rates.

GRAVITATIONAL ENCOUNTERS AND THE EVOLUTION OF GALACTIC NUCLEI. III. ANOMALOUS RELAXATION

Energy Technology Data Exchange (ETDEWEB)

Merritt, David [Department of Physics and Center for Computational Relativity and Gravitation, Rochester Institute of Technology, Rochester, NY 14623 (United States)

2015-09-01

This paper is the third in a series presenting the results of direct numerical integrations of the Fokker–Planck equation for stars orbiting a supermassive black hole (SBH) at the center of a galaxy. The algorithm of Paper II included diffusion coefficients that described the effects of random (“classical”) and correlated (“resonant”) relaxation. In this paper, the diffusion coefficients of Paper II have been generalized to account for the effects of “anomalous relaxation,” the qualitatively different way in which eccentric orbits evolve in the regime of rapid relativistic precession. Two functional forms for the anomalous diffusion coefficients are investigated, based on power-law or exponential modifications of the resonant diffusion coefficients. The parameters defining the modified coefficients are first constrained by comparing the results of Fokker–Planck integrations with previously published N-body integrations. Steady-state solutions are then obtained via the Fokker–Planck equation for models with properties similar to those of the Milky Way nucleus. Inclusion of anomalous relaxation leads to the formation of less prominent cores than in the case of resonant relaxation alone, due to the lengthening of diffusion timescales for eccentric orbits. Steady-state capture rates of stars by the SBH are found to always be less than capture rates in the presence of resonant relaxation alone.

GRAVITATIONAL ENCOUNTERS AND THE EVOLUTION OF GALACTIC NUCLEI. III. ANOMALOUS RELAXATION

International Nuclear Information System (INIS)

Merritt, David

2015-01-01

This paper is the third in a series presenting the results of direct numerical integrations of the Fokker–Planck equation for stars orbiting a supermassive black hole (SBH) at the center of a galaxy. The algorithm of Paper II included diffusion coefficients that described the effects of random (“classical”) and correlated (“resonant”) relaxation. In this paper, the diffusion coefficients of Paper II have been generalized to account for the effects of “anomalous relaxation,” the qualitatively different way in which eccentric orbits evolve in the regime of rapid relativistic precession. Two functional forms for the anomalous diffusion coefficients are investigated, based on power-law or exponential modifications of the resonant diffusion coefficients. The parameters defining the modified coefficients are first constrained by comparing the results of Fokker–Planck integrations with previously published N-body integrations. Steady-state solutions are then obtained via the Fokker–Planck equation for models with properties similar to those of the Milky Way nucleus. Inclusion of anomalous relaxation leads to the formation of less prominent cores than in the case of resonant relaxation alone, due to the lengthening of diffusion timescales for eccentric orbits. Steady-state capture rates of stars by the SBH are found to always be less than capture rates in the presence of resonant relaxation alone

Relaxation processes in optically excites metal clusters; Relaxationsprozesse in optisch angeregten Metallclustern

Energy Technology Data Exchange (ETDEWEB)

Stanzel, J.

2007-08-10

The present work is concerned with the dynamics of optically excited metal clusters in the gas phase. Small mass-selected gold and tungsten cluster anions (Au{sup -}{sub n}, n=5-8, 14, 20 and W{sup -}{sub n}, n=3-14) are studied using femtosecond time-resolved photoelectron spectroscopy. Depending on the electronic structure in the valence region as well as on the optical excitation energy fundamentally different relaxation processes are observed. In small gold cluster anions excited with 1.56 eV an isolated electronically excited state is populated. The time-dependent measurements are strongly sizedependent and open insights into photoinduced geometry changes of the nuclear framework. Oscillatory vibrational wavepacket motion in Au{sup -}{sub 5}, an extremely longlived ({tau} >90 ns) electronically excited state in Au{sup -}{sub 6} as well as photoinduced melting in Au{sup -}{sub 7} and Au{sup -}{sub 8} is monitored in real time. By increasing the OPTICAL excitation energy to 3.12 eV a completely different scenario is observed. A multitude of electronically excited states can be reached upon optical excitation and as a consequence electronic relaxation processes that take place on a time scale of 1 ps are dominating. This is shown for Au{sup -}{sub 7}, Au{sup -}{sub 14} and Au{sup -}{sub 20}. Compared to gold clusters, tungsten clusters are characterized by a significantly higher electronic density of states in the valence region. Therefore electronic relaxation processes are much more likely and take place on a significantly faster time scale. The fast electronic relaxation processes are distinguished from pure vibrational relaxation. It is shown that already in the four atomic tungsten cluster W{sup -}{sub 4} electronic relaxation processes take place on a time scale of 30 fs. In all investigated tungsten cluster anions (W{sup -}{sub n}, n=3-14) an equilibrium between electronic and vibrational system is reached within around 1 ps after optical excitation which

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

Mixed quantum-classical simulations of the vibrational relaxation of photolyzed carbon monoxide in a hemoprotein

Energy Technology Data Exchange (ETDEWEB)

Schubert, Alexander, E-mail: schubert@irsamc.ups-tlse.fr; Meier, Christoph [Laboratoire Collisions Agrégats et Réactivité, IRSAMC, UMR CNRS 5589, Université Paul Sabatier, 31062 Toulouse (France); Falvo, Cyril [Institut des Sciences Moléculaires d’Orsay (ISMO), CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay (France)

2016-08-07

We present mixed quantum-classical simulations on relaxation and dephasing of vibrationally excited carbon monoxide within a protein environment. The methodology is based on a vibrational surface hopping approach treating the vibrational states of CO quantum mechanically, while all remaining degrees of freedom are described by means of classical molecular dynamics. The CO vibrational states form the “surfaces” for the classical trajectories of protein and solvent atoms. In return, environmentally induced non-adiabatic couplings between these states cause transitions describing the vibrational relaxation from first principles. The molecular dynamics simulation yields a detailed atomistic picture of the energy relaxation pathways, taking the molecular structure and dynamics of the protein and its solvent fully into account. Using the ultrafast photolysis of CO in the hemoprotein FixL as an example, we study the relaxation of vibrationally excited CO and evaluate the role of each of the FixL residues forming the heme pocket.

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

Energy Technology Data Exchange (ETDEWEB)

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

2016-05-14

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

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

Science.gov (United States)

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

2016-05-01

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

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.

Non-equilibrium relaxation and near-arrest dynamics in colloidal suspensions

International Nuclear Information System (INIS)

Medina-Noyola, M; RamIrez-Gonzalez, Pedro

2009-01-01

In this work we propose a theory to describe the irreversible diffusive relaxation of the local concentration of a colloidal dispersion that proceeds toward its stable thermodynamic equilibrium state, but which may in the process be trapped in metastable or dynamically arrested states. The central assumption of this theory is that the irreversible relaxation of the macroscopically observed mean value n-bar(r,t) of the local concentration of colloidal particles is described by a diffusion equation involving a local mobility b*(r,t) that depends not only on the mean value n-bar(r,t) but also on the covariance σ(r,r';t)≡δn(r,t)δn(r',t)-bar of the fluctuations δn(r,t)≡n(r,t)-n-bar(r,t). This diffusion equation must hence be solved simultaneously with the relaxation equation for the covariance σ(r,r';t), and here we also derive the corresponding relaxation equation. The dependence of the local mobility b*(r,t) on the mean value and the covariance is determined by a self-consistent set of equations involving now the spatially and temporally non-local time-dependent correlation functions, which in a uniform system in equilibrium reduces to the self-consistent generalized Langevin equation (SCGLE) theory of colloid dynamics. The resulting general theory considers the possibility that these relaxation processes occur under the influence of external fields, such as gravitational forces acting in the process of sedimentation. In this paper, however, we describe a simpler application, in which the system remains spatially uniform during the irreversible relaxation process, and discuss the general features of the glass transition scenario predicted by this non-equilibrium theory.

Transient absorption microscopy studies of energy relaxation in graphene oxide thin film.

Science.gov (United States)

Murphy, Sean; Huang, Libai

2013-04-10

Spatial mapping of energy relaxation in graphene oxide (GO) thin films has been imaged using transient absorption microscopy (TAM). Correlated AFM images allow us to accurately determine the thickness of the GO films. In contrast to previous studies, correlated TAM-AFM allows determination of the effect of interactions of GO with the substrate and between stacked GO layers on the relaxation dynamics. Our results show that energy relaxation in GO flakes has little dependence on the substrate, number of stacked layers, and excitation intensity. This is in direct contrast to pristine graphene, where these factors have great consequences in energy relaxation. This suggests intrinsic factors rather than extrinsic ones dominate the excited state dynamics of GO films.

Transient absorption microscopy studies of energy relaxation in graphene oxide thin film

International Nuclear Information System (INIS)

Murphy, Sean; Huang, Libai

2013-01-01

Spatial mapping of energy relaxation in graphene oxide (GO) thin films has been imaged using transient absorption microscopy (TAM). Correlated AFM images allow us to accurately determine the thickness of the GO films. In contrast to previous studies, correlated TAM–AFM allows determination of the effect of interactions of GO with the substrate and between stacked GO layers on the relaxation dynamics. Our results show that energy relaxation in GO flakes has little dependence on the substrate, number of stacked layers, and excitation intensity. This is in direct contrast to pristine graphene, where these factors have great consequences in energy relaxation. This suggests intrinsic factors rather than extrinsic ones dominate the excited state dynamics of GO films. (paper)

Methyl group rotation and nuclear relaxation at low temperatures

International Nuclear Information System (INIS)

Zweers, A.E.

1976-01-01

This thesis deals with the proton spin-lattice relaxation of some methyl group compounds at liquid helium temperatures. In these molecular crystals, an energy difference between the ground and first rotational state of the methyl group occurs, the so-called tunnelling splitting, which is of the order of a few degrees Kelvin. This means that the high temperature approximation is inappropriate for the description of the occupation densities of the two lowest rotational levels. A description of the properties of the methyl group in connection with relaxation

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.

Role of step stiffness and kinks in the relaxation of vicinal (001) with zigzag [110] steps

Science.gov (United States)

Mahjoub, B.; Hamouda, Ajmi BH.; Einstein, TL.

2017-08-01

We present a kinetic Monte Carlo study of the relaxation dynamics and steady state configurations of 〈110〉 steps on a vicinal (001) simple cubic surface. This system is interesting because 〈110〉 (fully kinked) steps have different elementary excitation energetics and favor step diffusion more than 〈100〉 (nominally straight) steps. In this study we show how this leads to different relaxation dynamics as well as to different steady state configurations, including that 2-bond breaking processes are rate determining for 〈110〉 steps in contrast to 3-bond breaking processes for 〈100〉-steps found in previous work [Surface Sci. 602, 3569 (2008)]. The analysis of the terrace-width distribution (TWD) shows a significant role of kink-generation-annihilation processes during the relaxation of steps: the kinetic of relaxation, toward the steady state, is much faster in the case of 〈110〉-zigzag steps, with a higher standard deviation of the TWD, in agreement with a decrease of step stiffness due to orientation. We conclude that smaller step stiffness leads inexorably to faster step dynamics towards the steady state. The step-edge anisotropy slows the relaxation of steps and increases the strength of step-step effective interactions.

Hyperpolarized nanodiamond with long spin-relaxation times

Science.gov (United States)

Rej, Ewa; Gaebel, Torsten; Boele, Thomas; Waddington, David E. J.; Reilly, David J.

2015-10-01

The use of hyperpolarized agents in magnetic resonance, such as 13C-labelled compounds, enables powerful new imaging and detection modalities that stem from a 10,000-fold boost in signal. A major challenge for the future of the hyperpolarization technique is the inherently short spin-relaxation times, typically nanodiamond can be hyperpolarized at cryogenic and room temperature without the use of free radicals, and, owing to their solid-state environment, exhibit relaxation times exceeding 1 h. Combined with the already established applications of nanodiamonds in the life sciences as inexpensive fluorescent markers and non-cytotoxic substrates for gene and drug delivery, these results extend the theranostic capabilities of nanoscale diamonds into the domain of hyperpolarized magnetic resonance.

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 ...

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.

Photoacoustic Determination of Non-radiative Relaxation Time of Absorbing Centers in Maize Seeds

Science.gov (United States)

Domínguez-Pacheco, A.; Hernández-Aguilar, C.; Cruz-Orea, A.

2017-07-01

Using non-destructive photothermal techniques, it is possible to characterize non-homogenous materials to obtain its optical and thermal properties through photoacoustic spectroscopy (PAS). In photoacoustic (PA) phenomena, there are transient states of thermal excitation, when samples absorb the incident light; these states manifest an excitation process that generates the PA signal, being in direct relation with the non-radiative relaxation times with the sample absorbent centers. The objective of this study was to determine the non-radiative relaxation times associated with different absorbent centers of corn seeds ( Zea mays L.), by using PAS. A frequency scan was done at different wavelengths (350 nm, 470 nm and 650 nm) in order to obtain the non-radiative relaxation times with different types of maize seeds.

Excitation dynamics and relaxation in a molecular heterodimer

International Nuclear Information System (INIS)

Balevičius, V.; Gelzinis, A.; Abramavicius, D.; Mančal, T.; Valkunas, L.

2012-01-01

Highlights: ► Dynamics of excitation within a heterogenous molecular dimer. ► Excited states can be swapped due to different reorganization energies of monomers. ► Conventional excitonic basis becomes renormalized due to interaction with the bath. ► Relaxation is independent of mutual positioning of monomeric excited states. -- Abstract: The exciton dynamics in a molecular heterodimer is studied as a function of differences in excitation and reorganization energies, asymmetry in transition dipole moments and excited state lifetimes. The heterodimer is composed of two molecules modeled as two-level systems coupled by the resonance interaction. The system-bath coupling is taken into account as a modulating factor of the molecular excitation energy gap, while the relaxation to the ground state is treated phenomenologically. Comparison of the description of the excitation dynamics modeled using either the Redfield equations (secular and full forms) or the Hierarchical quantum master equation (HQME) is demonstrated and discussed. Possible role of the dimer as an excitation quenching center in photosynthesis self-regulation is discussed. It is concluded that the system-bath interaction rather than the excitonic effect determines the excitation quenching ability of such a dimer.

Texstar: The all-Texas educational satellite system

Science.gov (United States)

1990-01-01

Longhorn Satellite Company (LSC) has designed Texstar, and educational satellite communications system which will be considered as a means of equalizing the distribution of educational resources throughout the state of Texas. Texstar will be capable of broadcasting live lectures and documentaries in addition to transmitting data from a centralized receiving-transmitting station. Included in the design of Texstar is the system and subsystem design for the satellite and the design of the ground stations. The launch vehicle used will be the Texas-built Conestoga 421-48. The Texstar system incorporates three small satellites in slightly inclined geosynchronous orbits. Due to the configuration and spacing of these satellites, the system will be accessed as if it were one large, geostationary satellite. Texstar is shown to be a viable option to the educational crisis in the state of Texas.

Sleep, Stress & Relaxation: Rejuvenate Body & Mind

Science.gov (United States)

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

Ultrafast Carrier Relaxation in InN Nanowires Grown by Reactive Vapor Transport

Directory of Open Access Journals (Sweden)

Zervos Matthew

2008-01-01

Full Text Available Abstract We have studied femtosecond carrier dynamics in InN nanowires grown by reactive vapor transport. Transient differential absorption measurements have been employed to investigate the relaxation dynamics of photogenerated carriers near and above the optical absorption edge of InN NWs where an interplay of state filling, photoinduced absorption, and band-gap renormalization have been observed. The interface between states filled by free carriers intrinsic to the InN NWs and empty states has been determined to be at 1.35 eV using CW optical transmission measurements. Transient absorption measurements determined the absorption edge at higher energy due to the additional injected photogenerated carriers following femtosecond pulse excitation. The non-degenerate white light pump-probe measurements revealed that relaxation of the photogenerated carriers occurs on a single picosecond timescale which appears to be carrier density dependent. This fast relaxation is attributed to the capture of the photogenerated carriers by defect/surface related states. Furthermore, intensity dependent measurements revealed fast energy transfer from the hot photogenerated carriers to the lattice with the onset of increased temperature occurring at approximately 2 ps after pulse excitation.

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

Science.gov (United States)

Rustigan, Carol J.

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

Current State of Art of Satellite Altimetry

Directory of Open Access Journals (Sweden)

Łyszkowicz Adam

2017-12-01

Full Text Available One of the fundamental problems of modern geodesy is precise definition of the gravitational field and its changes in time. This is essential in positioning and navigation, geo-physics, geodynamics, oceanography and other sciences related to the climate and Earth’s environment. One of the major sources of gravity data is satellite altimetry that provides gravity data with almost 75% surface of the Earth. Satellite altimetry also provides data to study local, regional and global geophysical processes, the geoid model in the areas of oceans and seas. This technique can be successfully used to study the ocean mean dynamic topography. The results of the investigations and possible products of altimetry will provide a good material for the GGOS (Global Geodetic Observing System and institutions of IAS (International Altimetry Service.

Solid state dewetting and stress relaxation in a thin single crystalline Ni film on sapphire

International Nuclear Information System (INIS)

Rabkin, E.; Amram, D.; Alster, E.

2014-01-01

In this study, we deposited a 80 nm thick single crystalline Ni film on a sapphire substrate. Heat treatment of this film at 1000 °C followed by slow cooling resulted in the formation of faceted holes, star-like channel instabilities and faceted microwires. The ridges at the rims of faceted holes and channels exhibited a twinning orientation relationship with the rest of the film. A sub-nanometer-high hexagonal topography pattern on the surface of the unperturbed film was observed by atomic force microscopy. No such pattern was observed on the top facets of isolated Ni particles and hole ridges. We discuss the observed dewetting patterns in terms of the effects of Ni surface anisotropy and faceting on solid state dewetting. The hexagonal pattern on the surface of the unperturbed film was attributed to thermal stress relaxation in the film via dislocations glide. This work demonstrates that solid state dewetting of single crystalline metal films can be utilized for film patterning and for producing hierarchical surface topographies

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.

Differential saturation study of radial and angular modulation mechanisms of electron spin--lattice relaxation for trapped hydrogen atoms in sulfuric acid glasses. [X radiation

Energy Technology Data Exchange (ETDEWEB)

Plonka, A; Kevan, L

1976-11-01

A differential ESR saturation study of allowed transitions and forbidden proton spin-flip satellite transitions for trapped hydrogen atoms in sulfuric acid glasses indicates that angular modulation dominates the spin-lattice relaxation mechanisms and suggests that the modulation arises from motion of the H atom.

Education and the Satellite: Possibilities for Saudi Arabia?

Science.gov (United States)

Al-Sharhan, Jamal

2000-01-01

Discussion of developments in satellite communications and educational applications focuses on the possibilities of adapting satellite technology for instruction in developing countries. Topics include satellite use in Australia and the United States; and recommendations for the adoption of satellite technology in Saudi Arabia. (Author/LRW)

NASA satellite communications application research. Phase 2: Efficient high power, solid state amplifier for EFH communications

Science.gov (United States)

Benet, James

1993-01-01

The final report describes the work performed from 9 Jun. 1992 to 31 Jul. 1993 on the NASA Satellite Communications Application Research (SCAR) Phase 2 program, Efficient High Power, Solid State Amplifier for EHF Communications. The purpose of the program was to demonstrate the feasibility of high-efficiency, high-power, EHF solid state amplifiers that are smaller, lighter, more efficient, and less costly than existing traveling wave tube (TWT) amplifiers by combining the output power from up to several hundred solid state amplifiers using a unique orthomode spatial power combiner (OSPC).

Dynamic and structural characterisation of micellar solutions of surfactants by spin relaxation and translational diffusion

International Nuclear Information System (INIS)

Mahieu, Nathalie

1992-01-01

The work reported in this research thesis aimed at characterizing micellar phases formed by some surfactants (sodium carboxylates) in aqueous solution. After some recalls on nuclear magnetic resonance dealing with spin relaxation (longitudinal relaxation, transverse relaxation, relaxation in the rotating coordinate system, and crossed relaxation), and comments on the dipolar mechanism responsible of relaxation phenomena, the author presents the methods used for relaxation parameter measurement and the data processing software issued from experiments. He presents experiments which allowed the self-diffusion coefficient to be measured, reports data processing, and addresses problems of special diffusion and of coherence transfers during diffusion measurements. Results of proton relaxation measurements are then presented and discussed. They are used to determine the micellar state of the studied carboxylates. The case of the oleate is also addressed. Measurements of carbon-13 relaxation times are reported, and exploited in terms of structural parameters by using the Relaxator software. An original method of the hetero-nuclear Overhauser method is presented, and used to assess the average distance between water molecules and micelle surface [fr

Relaxation training methods for nurse managers in Hong Kong: a controlled study.

Science.gov (United States)

Yung, Paul M B; Fung, Man Yi; Chan, Tony M F; Lau, Bernard W K

2004-12-01

Nurse managers are under increased stress because of excessive workloads and hospitals' restructuring which is affecting their work tasks. High levels of stress could affect their mental health. Yet, few stress management training programmes are provided for this population. The purpose of this study was to apply stretch-release relaxation and cognitive relaxation training to enhance the mental health for nurse managers. A total of 65 nurse managers in Hong Kong were randomly assigned to stretch-release relaxation (n = 17), cognitive relaxation (n = 18), and a test control group (n = 35). Mental health status was assessed using the Chinese version of State-Trait Anxiety Inventory and the Chinese version of the General Health Questionnaire. Participants were assessed at the pretreatment session, the fourth posttreatment session, and at the 1-month follow-up session. The results revealed both the stretch-release and cognitive relaxation training enhanced mental health in nurse managers in Hong Kong. The application of relaxation training in enhancing mental health status for nurses and health professionals is discussed.

Control of muscle relaxation during anesthesia: a novel approach for clinical routine.

Science.gov (United States)

Stadler, Konrad S; Schumacher, Peter M; Hirter, Sibylle; Leibundgut, Daniel; Bouillon, Thomas W; Glattfelder, Adolf H; Zbinden, Alex M

2006-03-01

During general anesthesia drugs are administered to provide hypnosis, ensure analgesia, and skeletal muscle relaxation. In this paper, the main components of a newly developed controller for skeletal muscle relaxation are described. Muscle relaxation is controlled by administration of neuromuscular blocking agents. The degree of relaxation is assessed by supramaximal train-of-four stimulation of the ulnar nerve and measuring the electromyogram response of the adductor pollicis muscle. For closed-loop control purposes, a physiologically based pharmacokinetic and pharmacodynamic model of the neuromuscular blocking agent mivacurium is derived. The model is used to design an observer-based state feedback controller. Contrary to similar automatic systems described in the literature this controller makes use of two different measures obtained in the train-of-four measurement to maintain the desired level of relaxation. The controller is validated in a clinical study comparing the performance of the controller to the performance of the anesthesiologist. As presented, the controller was able to maintain a preselected degree of muscle relaxation with excellent precision while minimizing drug administration. The controller performed at least equally well as the anesthesiologist.

Carrier relaxation in (In,Ga)As quantum dots with magnetic field-induced anharmonic level structure

Energy Technology Data Exchange (ETDEWEB)

Kurtze, H.; Bayer, M. [Experimentelle Physik 2, TU Dortmund, D-44221 Dortmund (Germany)

2016-07-04

Sophisticated models have been worked out to explain the fast relaxation of carriers into quantum dot ground states after non-resonant excitation, overcoming the originally proposed phonon bottleneck. We apply a magnetic field along the quantum dot heterostructure growth direction to transform the confined level structure, which can be approximated by a Fock–Darwin spectrum, from a nearly equidistant level spacing at zero field to strong anharmonicity in finite fields. This changeover leaves the ground state carrier population rise time unchanged suggesting that fast relaxation is maintained upon considerable changes of the level spacing. This corroborates recent models explaining the relaxation by polaron formation in combination with quantum kinetic effects.

Applications of Geostationary Satellite Data to Aviation

Science.gov (United States)

Ellrod, Gary P.; Pryor, Kenneth

2018-03-01

Weather is by far the most important factor in air traffic delays in the United States' National Airspace System (NAS) according to the Federal Aviation Administration (FAA). Geostationary satellites have been an effective tool for the monitoring of meteorological conditions that affect aviation operations since the launch of the first Synchronous Meteorological Satellite (SMS) in the United States in 1974. This paper will review the global use of geostationary satellites in support of aviation weather since their inception, with an emphasis on the latest generation of satellites, such as Geostationary Operational Environmental Satellite (GOES)-R (16) with its Advanced Baseline Imager (ABI) and Geostationary Lightning Mapper (GLM). Specific applications discussed in this paper include monitoring of convective storms and their associated hazards, fog and low stratus, turbulence, volcanic hazards, and aircraft icing.

Combining walking and relaxation for stress reduction-A randomized cross-over trial in healthy adults.

Science.gov (United States)

Matzer, Franziska; Nagele, Eva; Lerch, Nikolaus; Vajda, Christian; Fazekas, Christian

2018-04-01

Both physical activity and relaxation have stress-relieving potential. This study investigates their combined impact on the relaxation response while considering participants' initial stress level. In a randomized cross-over trial, 81 healthy adults completed 4 types of short-term interventions for stress reduction, each lasting for 1 hr: (1) physical activity (walking) combined with resting, (2) walking combined with balneotherapy, (3) combined resting and balneotherapy, and (4) resting only. Saliva cortisol, blood pressure, state of mood, and relaxation were measured preintervention and postintervention. Stress levels were determined by validated questionnaires. All interventions were associated with relaxation responses in the variables saliva cortisol, blood pressure, state of mood, and subjective relaxation. No significant differences were found regarding the reduction of salivary cortisol (F = 1.30; p = .281). The systolic blood pressure was reduced best when walking was combined with balneotherapy or resting (F = 7.34; p stress levels (n = 25) felt more alert after interventions including balneotherapy, whereas they reported an increase of tiredness when walking was combined with resting (F = 3.20; p = .044). Results suggest that combining physical activity and relaxation (resting or balneotherapy) is an advantageous short-term strategy for stress reduction as systolic blood pressure is reduced best while similar levels of relaxation can be obtained. Copyright © 2017 John Wiley & Sons, Ltd.

Decay of Metastable State with Account of Agglomeration and Relaxation Processes

Directory of Open Access Journals (Sweden)

Victor Kurasov

2016-01-01

Full Text Available Theoretical description of the metastable phase decay kinetics in the presence of specific connections between the embryos of small sizes has been given. The theory of the decay kinetics in the presence of relaxation processes is constructed in analytical manner. The m-mers nucleation is investigated and the global kinetics of decay is also constructed in this case analytically.

Electronic relaxation processes in polyatomic molecules. Progress report, October 1, 1975--September 30, 1976

International Nuclear Information System (INIS)

Lim, E.C.

1976-09-01

Excitation energy dependence of radiationless decay rate under collision-free conditions was utilized as a probe of intramolecular vibrational relaxation in tetracene and pentacene. The results give evidence of vibrational relaxation which competes with electronic relaxation. The substitution dependence of T 1 (nπ*) → S 0 radiationless transition in monocyclic diazines and the temperature dependence of S 1 non-radiative decay rate in alcoholic solutions of polycyclic monoazines indicate that the vibronic interaction between the lowest energy nπ* and ππ* states leads to a rapid radiationless deactivation of the lower of the two electronic states. Finally, a photon-counting spectrofluorometer of very high sensitivity was constructed, and it was used to record T 2 → T 1 fluorescence in bromoanthracenes and S 2 → S 1 fluorescence in azulene. These spectra represent the first bona-fide, or the most convincing, observation of fluorescence between excited electronic states

An Instructional Satellite System for the United States: Preliminary Considerations.

Science.gov (United States)

DuMolin, James R.; Morgan, Robert P.

Based on educational, social, political, and other considerations, an instructional satellite system, AVSIN (Ausio-Visual Satellite Instruction), is hypothesized which represents one possible organizational and administrative arrangement for delivering large amounts of quality software to schools and learning centers. The AVSIN system is conceived…

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

KAUST Repository

Khan, Mohammed Zahed Mustafa

2011-12-01

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

The Use of a Satellite Human Interaction System in Conjunction with a Satellite Media Distribution System. Satellite Technology Demonstration, Technical Report No. 0217.

Science.gov (United States)

Dale, Joyce B.

Satellite Technology Demonstration (STD) was designed to provide data on the use of a satellite to deliver educational programs to 56 rural-isolated schools in eight Rocky Mountain States. Three series were broadcast: (1) a junior high school career development, (2) career development for public school administrators and teachers, and (3) topical…

Perturbation of longitudinal relaxation rate in rotating frame (PLRF) analysis for quantification of chemical exchange saturation transfer signal in a transient state.

Science.gov (United States)

Wang, Yi; Zhang, Yaoyu; Zhao, Xuna; Wu, Bing; Gao, Jia-Hong

2017-11-01

To develop a novel analytical method for quantification of chemical exchange saturation transfer (CEST) in the transient state. The proposed method aims to reduce the effects of non-chemical-exchange (non-CE) parameters on the CEST signal, emphasizing the effect of chemical exchange. The difference in the longitudinal relaxation rate in the rotating frame ( ΔR1ρ) was calculated based on perturbation of the Z-value by R1ρ, and a saturation-pulse-amplitude-compensated exchange-dependent relaxation rate (SPACER) was determined with a high-exchange-rate approximation. In both phantom and human subject experiments, MTRasym (representative of the traditional CEST index), ΔR1ρ, and SPACER were measured, evaluated, and compared by altering the non-CE parameters in a transient-state continuous-wave CEST sequence. In line with the theoretical expectation, our experimental data demonstrate that the effects of the non-CE parameters can be more effectively reduced using the proposed indices (  ΔR1ρ and SPACER) than using the traditional CEST index ( MTRasym). The proposed method allows for the chemical exchange weight to be better emphasized in the transient-state CEST signal, which is beneficial, in practice, for quantifying the CEST signal. Magn Reson Med 78:1711-1723, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

Picosecond energy relaxation in La0.67Ca0.33MnO3

International Nuclear Information System (INIS)

Dorosinets, Vladimir; Richter, Pablo; Mohler, Ernst; Roskos, Hartmut G.; Jakob, Gerhard

2005-01-01

Investigating the reflectance response dynamics of La 0.67 Ca 0.33 MnO 3 thin films after excitation by femtosecond laser pulses, we identify for the first time a picosecond relaxation step which only exists below the Curie temperature T C . The relaxation time increases from zero at T C to several picoseconds at low temperatures. The data can be explained with the existence of a magnetization-related effective energy gap, and assuming relaxation between these states to be mediated by a Frohlich-type electron-lattice interaction

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)

Resistive switching properties and low resistance state relaxation in Al/Pr0.7Ca0.3MnO3/Pt junctions

International Nuclear Information System (INIS)

Li Songlin; Liao, Z L; Li, J; Gang, J L; Zheng, D N

2009-01-01

Metal/insulator/metal structures composed of active Al top electrodes (TEs) and oxygen-deficient Pr 0.7 Ca 0.3 MnO 3 (PCMO) insulator layers are prepared on platinized silicon substrates. The junction resistance exhibits an obvious negative differential resistance region in the first bias sweep and an irreversible increase from 2 to 100 MΩ in repeated ±4 V sweeps. The pulse duration needed to fully switch the junctions is found to be on the order of milliseconds. When 100-500 μs negative pulses are used, the junctions show an incomplete switch to the low resistance state (LRS) which exhibits fluctuating resistances. The fluctuation in the LRS is suppressed and the high-to-low resistance ratio increases gradually when the negative pulse duration is increased from 100 to 500 μs. For relaxed junctions, pulse switching experiments reveal that the LRS undergoes a dynamically stable process at the beginning and then reaches a lower and metastable resistance value. Resistance retention tests also indicate that the high resistance state is very stable, while the metastable LRS gradually relaxes to higher resistance values. The experimental results are discussed with the formation and dissociation of an interfacial AlO x layer at the interface between Al TEs and PCMO layers.

Relaxations to Sparse Optimization Problems and Applications

Science.gov (United States)

Skau, Erik West

Parsimony is a fundamental property that is applied to many characteristics in a variety of fields. Of particular interest are optimization problems that apply rank, dimensionality, or support in a parsimonious manner. In this thesis we study some optimization problems and their relaxations, and focus on properties and qualities of the solutions of these problems. The Gramian tensor decomposition problem attempts to decompose a symmetric tensor as a sum of rank one tensors.We approach the Gramian tensor decomposition problem with a relaxation to a semidefinite program. We study conditions which ensure that the solution of the relaxed semidefinite problem gives the minimal Gramian rank decomposition. Sparse representations with learned dictionaries are one of the leading image modeling techniques for image restoration. When learning these dictionaries from a set of training images, the sparsity parameter of the dictionary learning algorithm strongly influences the content of the dictionary atoms.We describe geometrically the content of trained dictionaries and how it changes with the sparsity parameter.We use statistical analysis to characterize how the different content is used in sparse representations. Finally, a method to control the structure of the dictionaries is demonstrated, allowing us to learn a dictionary which can later be tailored for specific applications. Variations of dictionary learning can be broadly applied to a variety of applications.We explore a pansharpening problem with a triple factorization variant of coupled dictionary learning. Another application of dictionary learning is computer vision. Computer vision relies heavily on object detection, which we explore with a hierarchical convolutional dictionary learning model. Data fusion of disparate modalities is a growing topic of interest.We do a case study to demonstrate the benefit of using social media data with satellite imagery to estimate hazard extents. In this case study analysis we

Geostationary satellites collocation

CERN Document Server

Li, Hengnian

2014-01-01

Geostationary Satellites Collocation aims to find solutions for deploying a safe and reliable collocation control. Focusing on the orbital perturbation analysis, the mathematical foundations for orbit and control of the geostationary satellite are summarized. The mathematical and physical principle of orbital maneuver and collocation strategies for multi geostationary satellites sharing with the same dead band is also stressed. Moreover, the book presents some applications using the above algorithms and mathematical models to help readers master the corrective method for planning station keeping maneuvers. Engineers and scientists in the fields of aerospace technology and space science can benefit from this book. Hengnian Li is the Deputy Director of State Key Laboratory of Astronautic Dynamics, China.

Atmospheric Wind Relaxations and the Oceanic Response in the California Current Large Marine Ecosystem

Science.gov (United States)

Fewings, M. R.; Dorman, C. E.; Washburn, L.; Liu, W.

2010-12-01

On the West Coast of North America in summer, episodic relaxation of the upwelling-favorable winds causes warm water to propagate northward from southern to central California, against the prevailing currents [Harms and Winant 1998, Winant et al. 2003, Melton et al. 2009]. Similar wind relaxations are an important characteristic of coastal upwelling ecosystems worldwide. Although these wind relaxations have an important influence on coastal ocean dynamics, no description exists of the regional atmospheric patterns that lead to wind relaxations in southern California, or of the regional ocean response. We use QuikSCAT wind stress, North American Regional Reanalysis atmospheric pressure products, water temperature and velocity from coastal ocean moorings, surface ocean currents from high-frequency radars, and MODIS satellite sea-surface temperature and ocean color images to analyze wind relaxation events and the ocean response. We identify the events based on an empirical index calculated from NDBC buoy winds [Melton et al. 2009]. We describe the regional evolution of the atmosphere from the Gulf of Alaska to Baja California over the few days leading up to wind relaxations, and the coastal ocean temperature, color, and current response off southern and central California. We analyze ~100 wind relaxation events in June-September during the QuikSCAT mission, 1999-2009. Our results indicate south-central California wind relaxations in summer are tied to mid-level atmospheric low-pressure systems that form in the Gulf of Alaska and propagate southeastward over 3-5 days. As the low-pressure systems reach southern California, the atmospheric pressure gradient along the coast weakens, causing the surface wind stress to relax to near zero. The weak wind signal appears first at San Diego and propagates northward. QuikSCAT data indicate the relaxed winds extend over the entire Southern California Bight and up to 200 km offshore of central California. Atmospheric dynamics in

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

Science.gov (United States)

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

2010-12-01

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

Water interactions with varying molecular states of bovine casein: 2H NMR relaxation studies

International Nuclear Information System (INIS)

Kumosinski, T.F.; Pessen, H.; Prestrelski, S.J.; Farrell, H.M. Jr.

1987-01-01

The caseins occur in milk as spherical colloidal complexes of protein and salts with an average diameter of 1200 A, the casein micelles. Removal of Ca2+ is thought to result in their dissociation into smaller protein complexes stabilized by hydrophobic interactions and called submicelles. Whether these submicelles actually occur within the micelles as discrete particles interconnected by calcium phosphate salt bridges has been the subject of much controversy. A variety of physical measurements have shown that casein micelles contain an inordinately high amount of trapped water (2 to 7 g H 2 O/g protein). With this in mind it was of interest to determine if NMR relaxation measurements could detect the presence of this trapped water within the micelles, and to evaluate whether it is a continuum with picosecond correlation times or is associated in part with discrete submicellar structures with nanosecond motions. For this purpose the variations in 2 H NMR longitudinal and transverse relaxation rates of water with protein concentration were determined for bovine casein at various temperatures, under both submicellar and micellar conditions. D 2 O was used instead of H 2 O to eliminate cross-relaxation effects. From the protein concentration dependence of the relaxation rates, the second virial coefficient of the protein was obtained by nonlinear regression analysis. Using either an isotropic tumbling or an intermediate asymmetry model, degrees of hydration, v, and correlation times, tau c, were calculated for the caseins; from the latter parameter the Stokes radius, r, was obtained. Next, estimates of molecular weights were obtained from r and the partial specific volume. Values were in the range of those published from other methodologies for the submicelles

Structural relaxation: low temperature properties

International Nuclear Information System (INIS)

Cruz, F. de la

1984-01-01

We discuss the changes in transport and superconducting properties of amorphous Zr 70 Cu 30 , induced by thermal relaxation. The experimental results are used to investigate the relation between the microscopic parameters and the observed physical properties. It is shown that the density of eletronic states determines the shift Tc as well as the variation of the electrical resistivity. It is necessary to assume strong hybridization between s and d bands to understand the eletrodynamic response of the superconductor. (Author) [pt

Nuclear magnetic relaxation studies of semiconductor nanocrystals and solids

Energy Technology Data Exchange (ETDEWEB)

Sachleben, Joseph Robert [Lawrence Berkeley Lab., CA (United States); California Univ., Berkeley, CA (United States). Dept. of Chemistry

1993-09-01

Semiconductor nanocrystals, small biomolecules, and ¹³C enriched solids were studied through the relaxation in NMR spectra. Surface structure of semiconductor nanocrystals (CdS) was deduced from high resolution ¹H and ¹³C liquid state spectra of thiophenol ligands on the nanocrystal surfaces. The surface coverage by thiophenol was found to be low, being 5.6 and 26% for nanocrystal radii of 11.8 and 19.2 Å. Internal motion is estimated to be slow with a correlation time > 10^-8 s^-1. The surface thiophenol ligands react to form a dithiophenol when the nanocrystals were subjected to O₂ and ultraviolet. A method for measuring ¹⁴N-¹H J-couplings is demonstrated on pyridine and the peptide oxytocin; selective 2D T₁ and T₂ experiments are presented for measuring relaxation times in crowded spectra with overlapping peaks in 1D, but relaxation effects interfere. Possibility of carbon-carbon cross relaxation in ¹³C enriched solids is demonstrated by experiments on zinc acetate and L-alanine.

A minor conformation of a lanthanide tag on adenylate kinase characterized by paramagnetic relaxation dispersion NMR spectroscopy

International Nuclear Information System (INIS)

Hass, Mathias A. S.; Liu, Wei-Min; Agafonov, Roman V.; Otten, Renee; Phung, Lien A.; Schilder, Jesika T.; Kern, Dorothee; Ubbink, Marcellus

2015-01-01

NMR relaxation dispersion techniques provide a powerful method to study protein dynamics by characterizing lowly populated conformations that are in dynamic exchange with the major state. Paramagnetic NMR is a versatile tool for investigating the structures and dynamics of proteins. These two techniques were combined here to measure accurate and precise pseudocontact shifts of a lowly populated conformation. This method delivers valuable long-range structural restraints for higher energy conformations of macromolecules in solution. Another advantage of combining pseudocontact shifts with relaxation dispersion is the increase in the amplitude of dispersion profiles. Lowly populated states are often involved in functional processes, such as enzyme catalysis, signaling, and protein/protein interactions. The presented results also unveil a critical problem with the lanthanide tag used to generate paramagnetic relaxation dispersion effects in proteins, namely that the motions of the tag can interfere severely with the observation of protein dynamics. The two-point attached CLaNP-5 lanthanide tag was linked to adenylate kinase. From the paramagnetic relaxation dispersion only motion of the tag is observed. The data can be described accurately by a two-state model in which the protein-attached tag undergoes a 23° tilting motion on a timescale of milliseconds. The work demonstrates the large potential of paramagnetic relaxation dispersion and the challenge to improve current tags to minimize relaxation dispersion from tag movements

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…

Assessing performance of Bayesian state-space models fit to Argos satellite telemetry locations processed with Kalman filtering.

Directory of Open Access Journals (Sweden)

Mónica A Silva

Full Text Available Argos recently implemented a new algorithm to calculate locations of satellite-tracked animals that uses a Kalman filter (KF. The KF algorithm is reported to increase the number and accuracy of estimated positions over the traditional Least Squares (LS algorithm, with potential advantages to the application of state-space methods to model animal movement data. We tested the performance of two Bayesian state-space models (SSMs fitted to satellite tracking data processed with KF algorithm. Tracks from 7 harbour seals (Phoca vitulina tagged with ARGOS satellite transmitters equipped with Fastloc GPS loggers were used to calculate the error of locations estimated from SSMs fitted to KF and LS data, by comparing those to "true" GPS locations. Data on 6 fin whales (Balaenoptera physalus were used to investigate consistency in movement parameters, location and behavioural states estimated by switching state-space models (SSSM fitted to data derived from KF and LS methods. The model fit to KF locations improved the accuracy of seal trips by 27% over the LS model. 82% of locations predicted from the KF model and 73% of locations from the LS model were <5 km from the corresponding interpolated GPS position. Uncertainty in KF model estimates (5.6 ± 5.6 km was nearly half that of LS estimates (11.6 ± 8.4 km. Accuracy of KF and LS modelled locations was sensitive to precision but not to observation frequency or temporal resolution of raw Argos data. On average, 88% of whale locations estimated by KF models fell within the 95% probability ellipse of paired locations from LS models. Precision of KF locations for whales was generally higher. Whales' behavioural mode inferred by KF models matched the classification from LS models in 94% of the cases. State-space models fit to KF data can improve spatial accuracy of location estimates over LS models and produce equally reliable behavioural estimates.

Effect of iodine impurity on relaxation of photoexcited silver chloride

International Nuclear Information System (INIS)

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

2008-01-01

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

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...

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.

Effects of Relaxing and Arousing Music during Imagery Training on Dart-Throwing Performance, Physiological Arousal Indices, and Competitive State Anxiety.

Science.gov (United States)

Kuan, Garry; Morris, Tony; Kueh, Yee Cheng; Terry, Peter C

2018-01-01

Music that is carefully selected to match the requirements of activities and the characteristics of individuals has been shown to produce significant impacts on performance enhancement (Priest et al., 2004). There is also evidence that music can enhance imagery (Grocke and Wigram, 2007), although few studies have investigated the effects of music on imagery in the context of sport skills. In the present study, the effects of relaxing and arousing music during imagery on dart-throwing performance, physiological arousal indices, and competitive state anxiety, were investigated among 63 novice dart throwers. Participants had moderate-to-high imagery ability and were randomly assigned to unfamiliar relaxing music (URM), unfamiliar arousing music (UAM), or no music (NM) groups. Performance was assessed by 40 dart throws at a concentric circles dartboard before and after 12 imagery sessions over 4 weeks. Measures of galvanic skin response (GSR), peripheral temperature (PT), and heart rate (HR) were taken during imagery sessions 1 and 12, and the Competitive State Anxiety Inventory-2 Revised (CSAI-2R) was administered prior to the pre- and post-intervention performance task. Dart-throwing gain scores were significantly higher for URM than for UAM and NM, with no significant difference between UAM and NM (URM = 37.24 ± 5.66, UAM = 17.57 ± 5.30, and NM = 13.19 ± 6.14, F 2,62 = 5.03, p = 0.01, η 2 = 0.14). GSR, PT, and HR reflected lower arousal for URM than for UAM or NM. Significant decreases in somatic anxiety were evident for URM and UAM but not NM. Significant decreases in cognitive anxiety were evident for URM and NM but not UAM. Significant increases in self-confidence were evident for URM but not UAM or NM. Performance improved in all three conditions but URM was associated with the largest performance gain, the lowest physiological indices of arousal, and the most positive CSAI-2R profiles. Listening to relaxing music during imagery may have benefits for

Effects of Relaxing and Arousing Music during Imagery Training on Dart-Throwing Performance, Physiological Arousal Indices, and Competitive State Anxiety

Directory of Open Access Journals (Sweden)

Garry Kuan

2018-02-01

Full Text Available Music that is carefully selected to match the requirements of activities and the characteristics of individuals has been shown to produce significant impacts on performance enhancement (Priest et al., 2004. There is also evidence that music can enhance imagery (Grocke and Wigram, 2007, although few studies have investigated the effects of music on imagery in the context of sport skills. In the present study, the effects of relaxing and arousing music during imagery on dart-throwing performance, physiological arousal indices, and competitive state anxiety, were investigated among 63 novice dart throwers. Participants had moderate-to-high imagery ability and were randomly assigned to unfamiliar relaxing music (URM, unfamiliar arousing music (UAM, or no music (NM groups. Performance was assessed by 40 dart throws at a concentric circles dartboard before and after 12 imagery sessions over 4 weeks. Measures of galvanic skin response (GSR, peripheral temperature (PT, and heart rate (HR were taken during imagery sessions 1 and 12, and the Competitive State Anxiety Inventory-2 Revised (CSAI-2R was administered prior to the pre- and post-intervention performance task. Dart-throwing gain scores were significantly higher for URM than for UAM and NM, with no significant difference between UAM and NM (URM = 37.24 ± 5.66, UAM = 17.57 ± 5.30, and NM = 13.19 ± 6.14, F2,62 = 5.03, p = 0.01, η2 = 0.14. GSR, PT, and HR reflected lower arousal for URM than for UAM or NM. Significant decreases in somatic anxiety were evident for URM and UAM but not NM. Significant decreases in cognitive anxiety were evident for URM and NM but not UAM. Significant increases in self-confidence were evident for URM but not UAM or NM. Performance improved in all three conditions but URM was associated with the largest performance gain, the lowest physiological indices of arousal, and the most positive CSAI-2R profiles. Listening to relaxing music during imagery may have benefits for

Measurements of spin-lattice relaxation time in mixed alkali halide crystals

International Nuclear Information System (INIS)

Tannus, A.

1983-01-01

Using magneto-optic techniques the ground state spin-lattice relaxation times (T1) of 'F' centers in mixed Alkali Halide cristals (KCl-KBr), was studied. A computer assisted system to optically measure short relaxation times (approx. = 1mS), was described. The technique is based on the measurement of the Magnetic Circular Dicroism (MCD) presented by F centers. The T1 magnetic field dependency at 2 K (up to 65 KGauss), was obtained as well as the MCD spectra for different relative concentration at the mixed matrices. The theory developed by Panepucci and Mollenauer for F centers spin-lattice relaxation in pure matrices was modified to explain the behaviour of T1 in mixed cristals. The Direct Process results (T approx. = 2.0 K) compared against that theory shows that the main relaxation mecanism, up to 25 KGauss, continues to be phonon modulation of the hiperfine iteraction between F electrons and surrounding nuclei. (Author) [pt

Temperature Dependence of Logarithmic-like Relaxational Dynamics of Hydrated tRNA.

Science.gov (United States)

Chu, Xiang-Qiang; Mamontov, Eugene; O'Neill, Hugh; Zhang, Qiu

2013-03-21

The dynamics of RNA within the β-relaxation region of 10 ps to 1 ns is crucial to its biological function. Because of its simpler chemical building blocks and the lack of the side methyl groups, faster relaxational dynamics of RNA compared to proteins can be expected. However, the situation is actually opposite. In this work, the relaxational dynamics of tRNA is measured by quasielastic neutron scattering and analyzed using the mode coupling theory, originally developed for glass-forming liquids. Our results reveal that the dynamics of tRNA follows a log-decay within the β-relaxation region, which is an important trait demonstrated by the dynamics of proteins. The dynamics of hydrated tRNA and lysozyme compared in the time domain further demonstrate that the slower dynamics of tRNA relative to proteins originates from the difference in the folded states of tRNA and proteins, as well as the influence of their hydration water.

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

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.

Satellite Communication and Long Distance Education

OpenAIRE

Hafied Cangara

2016-01-01

Since Indonesia introduced communication satellite for telecommunication network, the satellite has brought a number of advantages for national development in various areas, such as telephone network, mass media development, business, education, politics, security and national defence as well as regional and International cooperation. In education, satellite communication could be used for long-distance learning as implemented by 13 state universities in eastern parts of Indonesia. It is also...

Use of satellite imagery to assess the trophic state of Miyun Reservoir, Beijing, China

International Nuclear Information System (INIS)

Wang Zhengjun; Hong Jianming; Du Guisen

2008-01-01

The objective of this research is to explore an appropriate way of monitoring and assessing water quality by satellite remote sensing techniques in the Miyun reservoir of Beijing, China. Two scene Thematic Mapper images in May and October of 2003 were acquired and simultaneous in situ measurements, sampling and analysis were conducted. Statistical analysis indicates that satellite-based normalized ratio vegetation index (NRVI) and in situ measured water chlorophyll a (Chl-a) concentration have very high correlation. Two linear regression models with high determination coefficients were constructed for NRVI and Chl-a of sample points. According to the modified trophic state index map, water quality in the western section of Miyun reservoir was consistently higher than in the eastern section during the two months tested. The trophic grade of the eastern reservoir remained mesotrophic with a tendency for eutrophication. - Remote sensing techniques can effectively monitor the change of water quality with time and space

Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells

International Nuclear Information System (INIS)

Budker, D.; Hollberg, L.; Kimball, D.F.; Kitching, J.; Pustclny, S.; Robinson, H.G.; Yashchuk, V.V.

2004-01-01

Using laser optical pumping, widths and frequency shifts are determined for microwave transitions between the components of the ground-state hyperfine structure for 85 Rb and 87 Rb atoms contained in vapor cells with alkane anti-relaxation coatings. The results are compared with data on Zeeman relaxation obtained in nonlinear magneto-optical rotation (NMOR) experiments, a comparison important for quantitative understanding of spin-relaxation mechanisms in coated cells. By comparing cells manufactured over a forty-year period we demonstrate the long-term stability of coated cells, which may be useful for atomic clocks and magnetometers

Investigation of microwave transitions and nonlinear magneto-optical rotation in anti-relaxation-coated cells

International Nuclear Information System (INIS)

Budker, Dmitry; Hollberg, Leo; Kimball, Derek F.; Kitching, J.; Pustelny, Szymon; Yashchuk, Valeriy V.

2004-01-01

Using laser optical pumping, widths and frequency shifts are determined for microwave transitions between ground-state hyperfine components of 85 Rb and 87 Rb atoms contained in vapor cells with alkane anti-relaxation coatings. The results are compared with data on Zeeman relaxation obtained in nonlinear magneto-optical rotation (NMOR) experiments, a comparison important for quantitative understanding of spin-relaxation mechanisms in coated cells. By comparing cells manufactured over a forty-year period we demonstrate the long-term stability of coated cells, an important property for atomic clocks and magnetometers

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....

Lattice Distortion Mediated Paramagnetic Relaxation in High-Spin High-Symmetry Molecular Magnets

Science.gov (United States)

Garg, Anupam

1998-08-01

Field-dependent maxima in the relaxation rate of the magnetic molecules Mn12-Ac and Fe8-tacn have commonly been ascribed to some resonant tunneling phenomena. We argue instead that the relaxation is purely due to phonons. The rate maxima arise because of a Jahn-Teller-like distortion caused by the coupling of phonons to degenerate Zeeman levels of the molecule at the top of the barrier. The binding energy of the distorted intermediate states lowers the barrier height and increases the relaxation rate. A nonperturbative calculation of this effect is carried out for a model system. An approximate result for the field variation near a maximum is found to agree reasonably with experiment.

Relaxation processes and physical aging in metallic glasses

Science.gov (United States)

Ruta, B.; Pineda, E.; Evenson, Z.

2017-12-01

Since their discovery in the 1960s, metallic glasses have continuously attracted much interest across the physics and materials science communities. In the forefront are their unique properties, which hold the alluring promise of broad application in fields as diverse as medicine, environmental science and engineering. However, a major obstacle to their wide-spread commercial use is their inherent temporal instability arising from underlying relaxation processes that can dramatically alter their physical properties. The result is a physical aging process which can bring about degradation of mechanical properties, namely through embrittlement and catastrophic mechanical failure. Understanding and controlling the effects of aging will play a decisive role in our on-going endeavor to advance the use of metallic glasses as structural materials, as well as in the more general comprehension of out-of-equilibrium dynamics in complex systems. This review presents an overview of the current state of the art in the experimental advances probing physical aging and relaxation processes in metallic glasses. Similarities and differences between other hard and soft matter glasses are highlighted. The topic is discussed in a multiscale approach, first presenting the key features obtained in macroscopic studies, then connecting them to recent novel microscopic investigations. Particular emphasis is put on the occurrence of distinct relaxation processes beyond the main structural process in viscous metallic melts and their fate upon entering the glassy state, trying to disentangle results and formalisms employed by the different groups of the glass-science community. A microscopic viewpoint is presented, in which physical aging manifests itself in irreversible atomic-scale processes such as avalanches and intermittent dynamics, ascribed to the existence of a plethora of metastable glassy states across a complex energy landscape. Future experimental challenges and the comparison with

Spin relaxation in semiconductor quantum rings and dots--a comparative study.

Science.gov (United States)

Zipper, Elżbieta; Kurpas, Marcin; Sadowski, Janusz; Maśka, Maciej M

2011-03-23

We calculate spin relaxation times due to spin-orbit-mediated electron-phonon interactions for experimentally accessible semiconductor quantum ring and dot architectures. We elucidate the differences between the two systems due to different confinement. The estimated relaxation times (at B = 1 T) are in the range between a few milliseconds to a few seconds. This high stability of spin in a quantum ring allows us to test it as a spin qubit. A brief discussion of quantum state manipulations with such a qubit is presented.

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....

Stretched exponential relaxation in molecular and electronic glasses

International Nuclear Information System (INIS)

Phillips, J.C.

1996-01-01

is often better than the quoted experimental accuracies ∼5%. The extrinsic cases are identified by explicit structural signatures which are discussed at length. The discussion also includes recent molecular dynamical simulations for metallic glasses, spin glasses, quasicrystals and polymers which have achieved the intermediate relaxed Kohlrausch state and which have obtained values of β in excellent agreement with the prediction of the microscopic theory. (author)

Non-equilibrium reaction and relaxation dynamics in a strongly interacting explicit solvent: F + CD3CN treated with a parallel multi-state EVB model.

Science.gov (United States)

Glowacki, David R; Orr-Ewing, Andrew J; Harvey, Jeremy N

2015-07-28

We describe a parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to explicitly correlated coupled cluster theory, we built a 64-state MS-EVB model designed to study the F + CD3CN → DF + CD2CN reaction in CD3CN solvent (recently reported in Dunning et al. [Science 347(6221), 530 (2015)]). This approach allows us to build a reactive potential energy surface whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. We ran molecular dynamics simulations to examine a range of observables which follow in the wake of the reactive event: energy deposition in the nascent reaction products, vibrational relaxation rates of excited DF in CD3CN solvent, equilibrium power spectra of DF in CD3CN, and time dependent spectral shifts associated with relaxation of the nascent DF. Many of our results are in good agreement with time-resolved experimental observations, providing evidence for the accuracy of our MS-EVB framework in treating both the solute and solute/solvent interactions. The simulations provide additional insight into the dynamics at sub-picosecond time scales that are difficult to resolve experimentally. In particular, the simulations show that (immediately following deuterium abstraction) the nascent DF finds itself in a non-equilibrium regime in two different respects: (1) it is highly vibrationally excited, with ∼23 kcal mol(-1) localized in the stretch and (2) its post-reaction solvation environment, in which it is not yet hydrogen-bonded to CD3CN solvent molecules, is intermediate between the non-interacting gas-phase limit and the solution-phase equilibrium limit. Vibrational relaxation of the nascent DF results in a spectral

How to implement decoy-state quantum key distribution for a satellite uplink with 50-dB channel loss

Science.gov (United States)

Meyer-Scott, Evan; Yan, Zhizhong; MacDonald, Allison; Bourgoin, Jean-Philippe; Hübel, Hannes; Jennewein, Thomas

2011-12-01

Quantum key distribution (QKD) takes advantage of fundamental properties of quantum physics to allow two distant parties to share a secret key; however, QKD is hampered by a distance limitation of a few hundred kilometers on Earth. The most immediate solution for global coverage is to use a satellite, which can receive separate QKD transmissions from two or more ground stations and act as a trusted node to link these ground stations. In this article we report on a system capable of performing QKD in the high loss regime expected in an uplink to a satellite using weak coherent pulses and decoy states. Such a scenario profits from the simplicity of its receiver payload, but has so far been considered to be infeasible due to very high transmission losses (40-50 dB). The high loss is overcome by implementing an innovative photon source and advanced timing analysis. Our system handles up to 57 dB photon loss in the infinite key limit, confirming the viability of the satellite uplink scenario. We emphasize that while this system was designed with a satellite uplink in mind, it could just as easily overcome high losses on any free space QKD link.

How to implement decoy-state quantum key distribution for a satellite uplink with 50-dB channel loss

International Nuclear Information System (INIS)

Meyer-Scott, Evan; Yan, Zhizhong; MacDonald, Allison; Bourgoin, Jean-Philippe; Huebel, Hannes; Jennewein, Thomas

2011-01-01

Quantum key distribution (QKD) takes advantage of fundamental properties of quantum physics to allow two distant parties to share a secret key; however, QKD is hampered by a distance limitation of a few hundred kilometers on Earth. The most immediate solution for global coverage is to use a satellite, which can receive separate QKD transmissions from two or more ground stations and act as a trusted node to link these ground stations. In this article we report on a system capable of performing QKD in the high loss regime expected in an uplink to a satellite using weak coherent pulses and decoy states. Such a scenario profits from the simplicity of its receiver payload, but has so far been considered to be infeasible due to very high transmission losses (40-50 dB). The high loss is overcome by implementing an innovative photon source and advanced timing analysis. Our system handles up to 57 dB photon loss in the infinite key limit, confirming the viability of the satellite uplink scenario. We emphasize that while this system was designed with a satellite uplink in mind, it could just as easily overcome high losses on any free space QKD link.

Non-rigid ultrasound image registration using generalized relaxation labeling process

Science.gov (United States)

Lee, Jong-Ha; Seong, Yeong Kyeong; Park, MoonHo; Woo, Kyoung-Gu; Ku, Jeonghun; Park, Hee-Jun

2013-03-01

This research proposes a novel non-rigid registration method for ultrasound images. The most predominant anatomical features in medical images are tissue boundaries, which appear as edges. In ultrasound images, however, other features can be identified as well due to the specular reflections that appear as bright lines superimposed on the ideal edge location. In this work, an image's local phase information (via the frequency domain) is used to find the ideal edge location. The generalized relaxation labeling process is then formulated to align the feature points extracted from the ideal edge location. In this work, the original relaxation labeling method was generalized by taking n compatibility coefficient values to improve non-rigid registration performance. This contextual information combined with a relaxation labeling process is used to search for a correspondence. Then the transformation is calculated by the thin plate spline (TPS) model. These two processes are iterated until the optimal correspondence and transformation are found. We have tested our proposed method and the state-of-the-art algorithms with synthetic data and bladder ultrasound images of in vivo human subjects. Experiments show that the proposed method improves registration performance significantly, as compared to other state-of-the-art non-rigid registration algorithms.

Geometrical relaxation of excitations in one-dimensional conjugated polymers; Giichijigen kyoeki kobunshi reiki jotai no shusa kozo kanwa

Energy Technology Data Exchange (ETDEWEB)

Yoshizawa, M. [Tohoku University, Sendai (Japan). Faculty of Engineering

1995-12-15

Large ultrafast optical nonlinearities in conjugated polymers have attracted much attention because of possible applications to nonlinear optical devices. One-dimensional systems such as conjugated polymers have localized excited states with geometrical relaxation. In this study, photoexcited states in polydiacetylene has been investigated by femtosecond Raman gain spectroscopy with 300-fs resolution. A new photoinduced Raman peak with lifetime of 1.5 ps has been observed at 1200cm{sup -1} for the first time. This peak indicates acetylene-like structure of the main chain relaxes to butatriene-like structure due to the formation of self-trapped exciting with the geometrical relaxation. The formation and decay kinetics of the Raman signals is consistent with the relaxation processes of exciting observed by femtosecond absorption spectroscopy. 8 refs., 5 figs.

Excited states

CERN Document Server

Lim, Edward C

1974-01-01

Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

Mismatch and misalignment: dark haloes and satellites of disc galaxies

Science.gov (United States)

Deason, A. J.; McCarthy, I. G.; Font, A. S.; Evans, N. W.; Frenk, C. S.; Belokurov, V.; Libeskind, N. I.; Crain, R. A.; Theuns, T.

2011-08-01

We study the phase-space distribution of satellite galaxies associated with late-type galaxies in the GIMIC suite of simulations. GIMIC consists of resimulations of five cosmologically representative regions from the Millennium Simulation, which have higher resolution and incorporate baryonic physics. Whilst the disc of the galaxy is well aligned with the inner regions (r˜ 0.1r200) of the dark matter halo, both in shape and angular momentum, there can be substantial misalignments at larger radii (r˜r200). Misalignments of >45° are seen in ˜30 per cent of our sample. We find that the satellite population aligns with the shape (and angular momentum) of the outer dark matter halo. However, the alignment with the galaxy is weak owing to the mismatch between the disc and dark matter halo. Roughly 20 per cent of the satellite systems with 10 bright galaxies within r200 exhibit a polar spatial alignment with respect to the galaxy - an orientation reminiscent of the classical satellites of the Milky Way. We find that a small fraction (˜10 per cent) of satellite systems show evidence for rotational support which we attribute to group infall. There is a bias towards satellites on prograde orbits relative to the spin of the dark matter halo (and to a lesser extent with the angular momentum of the disc). This preference towards co-rotation is stronger in the inner regions of the halo where the most massive satellites accreted at relatively early times are located. We attribute the anisotropic spatial distribution and angular momentum bias of the satellites at z= 0 to their directional accretion along the major axes of the dark matter halo. The satellite galaxies have been accreted relatively recently compared to the dark matter mass and have experienced less phase-mixing and relaxation - the memory of their accretion history can remain intact to z= 0. Understanding the phase-space distribution of the z= 0 satellite population is key for studies that estimate the host halo

Nonequilibrium thermodynamics and information theory: basic concepts and relaxing dynamics

International Nuclear Information System (INIS)

Altaner, Bernhard

2017-01-01

Thermodynamics is based on the notions of energy and entropy. While energy is the elementary quantity governing physical dynamics, entropy is the fundamental concept in information theory. In this work, starting from first principles, we give a detailed didactic account on the relations between energy and entropy and thus physics and information theory. We show that thermodynamic process inequalities, like the second law, are equivalent to the requirement that an effective description for physical dynamics is strongly relaxing. From the perspective of information theory, strongly relaxing dynamics govern the irreversible convergence of a statistical ensemble towards the maximally non-commital probability distribution that is compatible with thermodynamic equilibrium parameters. In particular, Markov processes that converge to a thermodynamic equilibrium state are strongly relaxing. Our framework generalizes previous results to arbitrary open and driven systems, yielding novel thermodynamic bounds for idealized and real processes. (paper)

Dielectric relaxation of barium strontium titanate and application to thin films for DRAM capacitors

Science.gov (United States)

Baniecki, John David

This thesis examines the issues associated with incorporating the high dielectric constant material Barium Strontium Titanate (BSTO) in to the storage capacitor of a dynamic random access memory (DRAM). The research is focused on two areas: characterizing and understanding the factors that control charge retention in BSTO thin films and modifying the electrical properties using ion implantation. The dielectric relaxation of BSTO thin films deposited by metal-organic chemical vapor deposition (MOCVD) is investigated in the time and frequency domains. It is shown that the frequency dispersion of the complex capacitance of BSTO thin films can be understood in terms of a power-law frequency dependence from 1mHz to 20GHz. From the correspondence between the time and frequency domain measurements, it is concluded that the power-law relaxation currents extend back to the nano second regime of DRAM operation. The temperature, field, and annealing dependence of the dielectric relaxation currents are also investigated and mechanisms for the observed power law relaxation are explored. An equivalent circuit model of a high dielectric constant thin film capacitor is developed based on the electrical measurements and implemented in PSPICE. Excellent agreement is found between the experimental and simulated electrical characteristics showing the utility of the equivalent circuit model in simulating the electrical properties of high dielectric constant thin films. Using the equivalent circuit model, it is shown that the greatest charge loss due to dielectric relaxation occurs during the first read after a refresh time following a write to the opposite logic state for a capacitor that has been written to the same logic state for a long time (opposite state write charge loss). A theoretical closed form expression that is a function of three material parameters is developed which estimates the opposite state write charge loss due to dielectric relaxation. Using the closed form

Thermal behaviour of the ESR Relaxation time in slightly dirty superconductors

International Nuclear Information System (INIS)

Schwachheim, G.; Machado, S.F.; Tsallis, C.

1978-07-01

The thermal behaviour of the ESR relaxation rate in slightly dirty superconductors is discussed for both exchange and spin-orbit interactions between the conduction electrons and the impurities. The sensibility to the electronic density of states is exhibited by using, in a modified BCS framework, an heuristic analytic form which avoids two of three defects of a previous similar treatment. The sudden increase (decrease) of the relaxation rate immediately below the critical temperature for the exchange (spin-orbit) case is confirmed. Reasonable agreement with experimental data in LaRu 2 ; Gd is obtained [pt

NMR of Cu satellites in the Kondo alloy CuCr

International Nuclear Information System (INIS)

Azevedo, L.J.; Follstaedt, D.; Narath, A.

1978-01-01

Using pulsed NMR techniques, resonances of Cu nuclei which are near neighbors to Cr impurities (c = 100 and 200 ppM) in CuCr (theta/sub k/ approx. 3K) have been studied in the temperature range 1 to 4K and applied fields H 0 = 20 to 125 kOe. At the highest fields and lowest temperatures the satellite shifts approach saturation. Above approx. 40 kOe the spin-lattice relaxation rate T 1 -1 is proportional to T/H 0 2 , indicating that the dominant relaxation mechanism arises from transverse fluctuations of a polarized local moment. The measured rates yield a local-moment/conduction-electron exchange interaction vertical bar J 0 vertical bar/g = 0.30, where g is the Cr g-value. Below approx. 40 kOe T 1 -1 appears to be slightly enhanced in comparison with the high-field behavior, but becomes field independent below approx. 30 kOe. Both effects are attributed to Kondo anomalies

Vibrational Relaxation of Ground-State Oxygen Molecules With Atomic Oxygen and Carbon Dioxide

Science.gov (United States)

Saran, D. V.; Pejakovic, D. A.; Copeland, R. A.

2008-12-01

Vertical water vapor profiles are key to understanding the composition and energy budget in the mesosphere and lower thermosphere (MLT). The SABER instrument onboard NASA's TIMED satellite measures such profiles by detecting H2O(ν2) emission in the 6.8 μm region. Collisional deactivation of vibrationally excited O2, O2(X3Σ-g, υ = 1) + H2O ↔ O2(X3Σ-g, υ = 0) + H2O(ν2), is an important source of H2O(ν2). A recent study has identified two other processes involving excited O2 that control H2O(ν2) population in the MLT: (1) the vibrational-translational (V-T) relaxation of O2(X3Σ-g, υ = 1) level by atomic oxygen and (2) the V-V exchange between CO2 and excited O2 molecules [1]. Over the past few years SRI researchers have measured the atomic oxygen removal process mentioned above at room temperature [2] and 240 K [3]. These measurements have been incorporated into the models for H2O(ν2) emission [1]. Here we report laboratory studies of the collisional removal of O2(X3Σ-g, υ = 1) by O(3P) at room temperature and below, reaching temperatures relevant to mesopause and polar summer MLT (~150 K). Instead of directly detecting the O2(X3Σ-g, υ = 1) population, a technically simpler approach is used in which the υ = 1 level of the O2(a1Δg) state is monitored. A two-laser method is employed, in which the pulsed output of the first laser near 285 nm photodissociates ozone to produce atomic oxygen and O2(a1Δg, υ = 1), and the pulsed output of the second laser detects O2(a1Δg, υ = 1) via resonance-enhanced multiphoton ionization. With ground-state O2 present, owing to the rapid equilibration of the O2(X3Σ-g, υ = 1) and O2(a1Δg, υ = 1) populations via the processes O2(a1Δg, υ = 1) + O2(X3Σ-g, υ = 0) ↔ O2(a1Δg, υ = 0) + O2(X3Σ-g, υ = 1), the information on the O2(X3Σ-g, υ = 1) kinetics is extracted from the O2(a1Δg, υ = 1) temporal evolution. In addition, measurements of the removal of O2(X3Σ-g, υ = 1) by CO2 at room temperature will also

Multivariate analysis of electrical impedance spectra for relaxed and contracted skeletal muscle

International Nuclear Information System (INIS)

Zagar, T; Krizaj, D

2008-01-01

Four-electrode impedance spectra of relaxed and contracted muscle biceps brachii were analyzed in an adult human subject over the frequency range from 300 Hz to 75 kHz. A feasibility of the principal component analysis of bioimpedance measurement for the evaluation of skeletal muscle contractile state was examined. The principal components score plots show a data grouping of the impedance spectra from the two muscle groups. The classification was performed using a soft independent modeling of class analogy (SIMCA) method. The data set comprised 32 samples (16 samples of contracted muscle and 16 samples of relaxed muscle). The leave-one-out test of the classification yields about 80% of correctly classified samples (11 samples for contracted and 15 samples for relaxed muscle)

Beta relaxation of nonpolymeric liquids close to the glass transition

DEFF Research Database (Denmark)

Olsen, Niels Boye; Christensen, Tage Emil; Dyre, Jeppe

2000-01-01

Dielectric beta relaxation in a pyridine-toluene solution is studied close to the glass transition. Loss peak frequency and maximum loss both exhibit thermal hysteresis. An annealing-state-independent parameter involving loss and loss peak frequency is identified. This parameter has a simple...

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

Science.gov (United States)

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

2017-10-21

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

Effects of hydrolysis on solid-state relaxation and stickiness behavior of sodium caseinate-lactose powders.

Science.gov (United States)

Mounsey, J S; Hogan, S A; Murray, B A; O'Callaghan, D J

2012-05-01

Hydrolyzed or nonhydrolyzed sodium caseinate-lactose dispersions were spray dried, at a protein: lactose ratio of 0.5, to examine the effects of protein hydrolysis on relaxation behavior and stickiness of model powders. Sodium caseinate (NC) used included a nonhydrolyzed control (DH 0) and 2 hydrolyzed variants (DH 8.3 and DH 15), where DH = degree of hydrolysis (%). Prior to spray drying, apparent viscosities of liquid feeds (at 70°C) at a shear rate of 20/s were 37.6, 3.14, and 3.19 mPa·s, respectively, for DH 0, DH 8, and DH 15 dispersions. Powders containing hydrolyzed casein were more susceptible to sticking than those containing intact NC. The former had also lower bulk densities and powder particle sizes. Scanning electron microscopy showed that hydrolyzed powders had thinner particle walls and were more friable than powders containing intact NC. Secondary structure of caseinates, determined by Fourier transform infrared spectroscopy, was affected by the relative humidity of storage and the presence of lactose as co-solvent rather than its physical state. Glass transition temperatures and lactose crystallization temperatures, determined by differential scanning calorimetry were not affected by caseinate hydrolysis, although the effects of protein hydrolysis on glass-rubber transitions (T(gr)) could be determined by thermo-mechanical analysis. Powders containing hydrolyzed NC had lower T(gr) values (~30°C) following storage at a higher subcrystallization relative humidity (33%) compared with powder with nonhydrolyzed NC (T(gr) value of ~40°C), an effect that reflects more extensive plasticization of powder matrices by moisture. Results support that sodium caseinate-lactose interactions were weak but that relaxation behavior, as determined by the susceptibility of powder to sticking, was affected by hydrolysis of sodium caseinate. Copyright © 2012 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

H-functions and mixing in violent relaxation

International Nuclear Information System (INIS)

Tremaine, S.; Henon, M.; Lynden-Bell, D.

1986-01-01

An H-function is any function of the phase space distribution function F(x,v) which is non-decreasing with time. In collisionless systems Boltzmann's H-function - integral F log F dx dv is only one of a variety of H-functions of the form - integral C(F) dx dv, where C is any convex function. Every equilibrium stellar system in which the distribution function is a decreasing function of the energy alone is a stationary point of some H-function of this form. During violent relaxation, all such H-functions must increase, and the distribution function is said to become 'more mixed'. A simple criterion is given for determining whether a given distribution function is more mixed than another; this criterion is used to show that a violently relaxed galaxy resembles observed elliptical galaxies only if the initial state is cold or clumpy. (author)

Ultrafast Physics Behind the Nonradiative Relaxation Process of Chromium Ions in Forsterite Crystals.

Science.gov (United States)

Demos, Stavros Gregorios

The nonradiative relaxation following photoexcitation has been studied in Cr^{4+} -doped forsterite (Mg_2SiO _4) using picosecond laser excitation and ultrasensitive photon counting detection. The experimental techniques utilized were time resolved antiStokes Raman scattering and up-converted hot and ordinary luminescence. The up-converted hot luminescence technique allowed the investigation of the upper state nonradiative relaxation of the excited state manifold of Cr^{4+ }-doped forsterite. The excitation involves the absorption of two photons per photoexcited ion in a two-step absorption. Discrete peaks are observed in the hot up-converted luminescence spectrum and are attributed to the population of nonequilibrium vibronic levels during the deexcitation of the ions by phonon emission. This work reveals that the phonon modes participating in the initial steps of the nonradiative relaxation of the photoexcited ions have energies 218 +/- 20, 325 +/- 20, 365 +/- 20 and 513 +/- 12 cm^ {-1}. The shape of the luminescence spectral envelope suggests two electronic bottlenecks at ~2.1 and ~2.45 eV associated with slower rates of vibrational relaxation at different parts of the excited state manifold. Time resolved measurements indicated that the average time for phonon emission is of the order of hundreds of fs. Information on the nonequilibrium phonon dynamics of the 225, 335 and 370 cm^{-1} modes of forsterite has been obtained using time resolved Raman scattering. Laser pulses of 450 fs in duration and 590 nm in wavelength were used to excite the Cr ions 2.1 eV above the ground state. The probe pulses (obtained from the same laser) are monitoring the nonequilibrium phonon population through the intensity of the antiStokes Raman lines at various pump-probe delay times. Experiments were performed at room and liquid nitrogen temperatures. The observed nonequilibrium phonon populations are associated with the overall complex nonradiative decay following the excitation of

Efficient all solid-state UV source for satellite-based lidar applications.

Energy Technology Data Exchange (ETDEWEB)

Armstrong, Darrell Jewell; Smith, Arlee Virgil

2003-07-01

A satellite-based UV-DIAL measurement system would allow continuous global monitoring of ozone concentration in the upper atmosphere. However such systems remain difficult to implement because aerosol-scattering return signals for satellite-based lidars are very weak. A suitable system must produce high-energy UV pulses at multiple wavelengths with very high efficiency. For example, a nanosecond system operating at 10 Hz must generate approximately 1 J per pulse at 308-320 nm. An efficient space-qualified wavelength-agile system based on a single UV source that can meet this requirement is probably not available using current laser technology. As an alternative, we're pursuing a multi-source approach employing all-solid-state modules that individually generate 300-320 nm light with pulse energies in the range of 50-200 mJ, with transform-limited bandwidths and good beam quality. Pulses from the individual sources can be incoherently summed to obtain the required single-pulse energy. These sources use sum-frequency mixing of the 532 nm second harmonic of an Nd:YAG pump laser with 731-803 nm light derived from a recently-developed, state-of-the-art, nanosecond optical parametric oscillator. Two source configurations are under development, one using extra-cavity sum-frequency mixing, and the other intra-cavity sum-frequency mixing. In either configuration, we hope to obtain sum-frequency mixing efficiency approaching 60% by carefully matching the spatial and temporal properties of the laser and OPO pulses. This ideal balance of green and near-IR photons requires an injection-seeded Nd:YAG pump-laser with very high beam quality, and an OPO exhibiting unusually high conversion efficiency and exceptional signal beam quality. The OPO employs a singly-resonant high-Fresnel-number image-rotating self-injection-seeded nonplanar-ring cavity that achieves pump depletion > 65% and produces signal beams with M{sup 2} {approx} 3 at pulse energies exceeding 50 mJ. Pump beam

Influence of relaxation processes on the evaluation of the metastable defect density in Cu(In,Ga)Se{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Maciaszek, M.; Zabierowski, P. [Faculty of Physics, Warsaw University of Technology, Koszykowa 75, Warszawa 00 662 (Poland)

2016-06-07

In this contribution, we investigated by means of numerical simulations the influence of relaxation processes related to metastable defects on electrical characteristics of Cu(In,Ga)Se{sub 2}. In particular, we analyzed the relaxation of a metastable state induced by illumination at a fixed temperature as well as the dependence of the hole concentration on the temperature during cooling. The knowledge of these two relaxation processes is crucial in the evaluation of the hole concentration in the relaxed state and after light soaking. We have shown that the distribution of the metastable defects can be considered frozen below 200 K. The hole capture cross section was estimated as ∼3 × 10{sup −15} cm{sup 2}. It was shown that the usually used cooling rates may lead to relevant changes of the hole concentration. We calculated the lower limit of the hole concentration after cooling, and we presented how it depends on densities of shallow acceptors and metastable defects. Moreover, we proposed a method which allows for the evaluation of shallow acceptor and metastable defect densities from two capacitance-voltage profiles measured in the relaxed and light soaking states. Finally, we indicated experimental conditions in which the influence of relaxation processes on the accuracy of this method is the smallest.

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....

Conformational exchange of aromatic side chains characterized by L-optimized TROSY-selected ¹³C CPMG relaxation dispersion.

Science.gov (United States)

Weininger, Ulrich; Respondek, Michal; Akke, Mikael

2012-09-01

Protein dynamics on the millisecond time scale commonly reflect conformational transitions between distinct functional states. NMR relaxation dispersion experiments have provided important insights into biologically relevant dynamics with site-specific resolution, primarily targeting the protein backbone and methyl-bearing side chains. Aromatic side chains represent attractive probes of protein dynamics because they are over-represented in protein binding interfaces, play critical roles in enzyme catalysis, and form an important part of the core. Here we introduce a method to characterize millisecond conformational exchange of aromatic side chains in selectively (13)C labeled proteins by means of longitudinal- and transverse-relaxation optimized CPMG relaxation dispersion. By monitoring (13)C relaxation in a spin-state selective manner, significant sensitivity enhancement can be achieved in terms of both signal intensity and the relative exchange contribution to transverse relaxation. Further signal enhancement results from optimizing the longitudinal relaxation recovery of the covalently attached (1)H spins. We validated the L-TROSY-CPMG experiment by measuring fast folding-unfolding kinetics of the small protein CspB under native conditions. The determined unfolding rate matches perfectly with previous results from stopped-flow kinetics. The CPMG-derived chemical shift differences between the folded and unfolded states are in excellent agreement with those obtained by urea-dependent chemical shift analysis. The present method enables characterization of conformational exchange involving aromatic side chains and should serve as a valuable complement to methods developed for other types of protein side chains.

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

Science.gov (United States)

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

2004-08-01

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

7 CFR 611.22 - Availability of satellite imagery.

Science.gov (United States)

2010-01-01

... 7 Agriculture 6 2010-01-01 2010-01-01 false Availability of satellite imagery. 611.22 Section 611... § 611.22 Availability of satellite imagery. Cloud-free maps of the United States based on imagery received from a satellite are prepared and released to the pubic by NRCS. The maps offer the first image of...

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.

Alignment of Ar+ [3P]4p2P03/2 satellite state from the polarization analysis of fluorescent radiation after photoionization

International Nuclear Information System (INIS)

Yenen, O.; McLaughlin, K.W.; Jaecks, D.H.

1997-01-01

The measurement of the polarization of radiation from satellite states of Ar + formed after the photoionization of Ar provides detailed information about the nature of doubly excited states, magnetic sublevel cross sections and partial wave ratios of the photo-ejected electrons. Since the formation of these satellite states is a weak process, it is necessary to use a high flux beam of incoming photons. In addition, in order to resolve the many narrow doubly excited Ar resonances, the incoming photons must have a high resolution. The characteristics of the beam line 9.0.1 of the Advanced Light Source fulfill these requirements. The authors determined the polarization of 4765 Angstrom fluorescence from the Ar + [ 3 P] 4p 2 P 3/2 0 satellite state formed after photoionization of Ar by photons from the 9.0.1 beam line of ALS in the 35.620-38.261 eV energy range using a resolution of approximately 12,700. This is accomplished by measuring the intensities of the fluorescent light polarized parallel (I parallel) and perpendicular (I perpendicular) to the polarization axis of the incident synchrotron radiation using a Sterling Optics 105MB polarizing filter. The optical system placed at 90 degrees with respect to the polarization axis of the incident light had a narrow band interference filter (δλ=0.3 nm) to isolate the fluorescent radiation

Grid Cell Relaxation Effects on the High Frequency Vibration Characteristics

International Nuclear Information System (INIS)

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

2015-01-01

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

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....

Estimating Rain Attenuation In Satellite Communication Links

Science.gov (United States)

Manning, R. M.

1991-01-01

Attenuation computed with help of statistical model and meteorological data. NASA Lewis Research Center Satellite Link Attenuation Model (SLAM) program QuickBASIC computer program evaluating static and dynamic statistical assessment of impact of rain attenuation on communication link established between Earth terminal and geosynchronous satellite. Application in specification, design, and assessment of satellite communication links for any terminal location in continental United States. Written in Microsoft QuickBASIC.

Relaxation oscillations and transport barrier dynamics in tokamak edge plasmas

International Nuclear Information System (INIS)

Benkadda, Sadruddin; Beyer, Peter; Fuhr-Chaudier, Guillaume; Garbet, Xavier; Ghendrih, Philippe; Sarazin, Yanick

2004-01-01

Oscillations of turbulent transport of particles and energy in magnetically confined plasmas can be easily observed in simulations of a variety of turbulence models. These oscillations typically involve a mechanism of energy exchange between fluctuations and a poloidal shear flow. This kind of ''predator-prey'' mechanism is found to be not relevant for transport barrier relaxations. In RBM simulations of resistive ballooning turbulence with transport barrier, relaxation oscillations of the latter are observed even in the case of frozen poloidal shear flow. These relaxations are due to a transitory growth of a mode localized at the barrier center. A one-dimensional model for the evolution of such a mode in the presence of a shear flow describes a transitory growth of an initial perturbation. Oscillations in the case of a finite steady-state shear flow are possible due to the coupling of the mode to the dynamics of the pressure profile. (author)

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.

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.

Aging of the Johari-Goldstein relaxation in the glass-forming liquids sorbitol and xylitol

Science.gov (United States)

Yardimci, Hasan; Leheny, Robert L.

2006-06-01

Employing frequency-dependent dielectric susceptibility we characterize the aging in two supercooled liquids, sorbitol and xylitol, below their calorimetric glass transition temperatures. In addition to the alpha relaxation that tracks the structural dynamics, the susceptibility of both liquids possesses a secondary Johari-Goldstein relaxation at higher frequencies. Following a quench through the glass transition, the susceptibility slowly approaches the equilibrium behavior. For both liquids, the magnitude of the Johari-Goldstein relaxation displays a dependence on the time since the quench, or aging time, that is quantitatively very similar to the age dependence of the alpha peak frequency. The Johari-Goldstein relaxation time remains constant during aging for sorbitol while it decreases slightly with age for xylitol. Hence, one cannot sensibly assign a fictive temperature to the Johari-Goldstein relaxation. This behavior contrasts with that of liquids lacking distinct Johari-Goldstein peaks for which the excess wing of the alpha peak tracks the main part of the peak during aging, enabling the assignment of a single fictive temperature to the entire spectrum. The aging behavior of the Johari-Goldstein relaxation time further calls into question the possibility that the relaxation time possesses stronger temperature dependence in equilibrium than is observed in the out-of-equilibrium state below the glass transition.

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....

Non-equilibrium reaction and relaxation dynamics in a strongly interacting explicit solvent: F + CD{sub 3}CN treated with a parallel multi-state EVB model

Energy Technology Data Exchange (ETDEWEB)

Glowacki, David R., E-mail: drglowacki@gmail.com [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Department of Computer Science, University of Bristol, Bristol BS8 1UB (United Kingdom); PULSE Institute and Department of Chemistry, Stanford University, Stanford, California 94305 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Orr-Ewing, Andrew J. [School of Chemistry, University of Bristol, Bristol BS8 1TS (United Kingdom); Harvey, Jeremy N. [Department of Chemistry, KU Leuven, Celestijnenlaan 200F, B-3001 Heverlee (Belgium)

2015-07-28

We describe a parallelized linear-scaling computational framework developed to implement arbitrarily large multi-state empirical valence bond (MS-EVB) calculations within CHARMM and TINKER. Forces are obtained using the Hellmann-Feynman relationship, giving continuous gradients, and good energy conservation. Utilizing multi-dimensional Gaussian coupling elements fit to explicitly correlated coupled cluster theory, we built a 64-state MS-EVB model designed to study the F + CD{sub 3}CN → DF + CD{sub 2}CN reaction in CD{sub 3}CN solvent (recently reported in Dunning et al. [Science 347(6221), 530 (2015)]). This approach allows us to build a reactive potential energy surface whose balanced accuracy and efficiency considerably surpass what we could achieve otherwise. We ran molecular dynamics simulations to examine a range of observables which follow in the wake of the reactive event: energy deposition in the nascent reaction products, vibrational relaxation rates of excited DF in CD{sub 3}CN solvent, equilibrium power spectra of DF in CD{sub 3}CN, and time dependent spectral shifts associated with relaxation of the nascent DF. Many of our results are in good agreement with time-resolved experimental observations, providing evidence for the accuracy of our MS-EVB framework in treating both the solute and solute/solvent interactions. The simulations provide additional insight into the dynamics at sub-picosecond time scales that are difficult to resolve experimentally. In particular, the simulations show that (immediately following deuterium abstraction) the nascent DF finds itself in a non-equilibrium regime in two different respects: (1) it is highly vibrationally excited, with ∼23 kcal mol{sup −1} localized in the stretch and (2) its post-reaction solvation environment, in which it is not yet hydrogen-bonded to CD{sub 3}CN solvent molecules, is intermediate between the non-interacting gas-phase limit and the solution-phase equilibrium limit. Vibrational

Satellites

International Nuclear Information System (INIS)

Burns, J.A.; Matthews, M.S.

1986-01-01

The present work is based on a conference: Natural Satellites, Colloquium 77 of the IAU, held at Cornell University from July 5 to 9, 1983. Attention is given to the background and origins of satellites, protosatellite swarms, the tectonics of icy satellites, the physical characteristics of satellite surfaces, and the interactions of planetary magnetospheres with icy satellite surfaces. Other topics include the surface composition of natural satellites, the cratering of planetary satellites, the moon, Io, and Europa. Consideration is also given to Ganymede and Callisto, the satellites of Saturn, small satellites, satellites of Uranus and Neptune, and the Pluto-Charon system

Muon spin relaxation studies of heavy fermion superconductors

International Nuclear Information System (INIS)

Heffner, R.H.

1993-01-01

This talk will focus recent developments in our understanding of heavy fermion (HF) superconductors and the role that positive muon spin relaxation (μSR) studies have played in helping to elucidate their properties. As illustrations two systems will be discussed: (1) UPd 2 Al 3 , one of the most recently discovered HF superconductors, which also displays coexisting magnetic order and (2) UBe 3 doped with small quantities Of Th substituted for U, which displays an interplay between its superconducting and magnetic ground states, leading to multiple superconducting states

Ligand manipulation of charge transfer excited state relaxation and spin crossover in [Fe(2,2′-bipyridine2(CN2

Directory of Open Access Journals (Sweden)

Kasper S. Kjær

2017-07-01

Full Text Available We have used femtosecond resolution UV-visible and Kβ x-ray emission spectroscopy to characterize the electronic excited state dynamics of [Fe(bpy2(CN2], where bpy=2,2′-bipyridine, initiated by metal-to-ligand charge transfer (MLCT excitation. The excited-state absorption in the transient UV-visible spectra, associated with the 2,2′-bipyridine radical anion, provides a robust marker for the MLCT excited state, while the transient Kβ x-ray emission spectra provide a clear measure of intermediate and high spin metal-centered excited states. From these measurements, we conclude that the MLCT state of [Fe(bpy2(CN2] undergoes ultrafast spin crossover to a metal-centered quintet excited state through a short lived metal-centered triplet transient species. These measurements of [Fe(bpy2(CN2] complement prior measurement performed on [Fe(bpy3]2+ and [Fe(bpy(CN4]2− in dimethylsulfoxide solution and help complete the chemical series [Fe(bpyN(CN6–2N]2N-4, where N = 1–3. The measurements confirm that simple ligand modifications can significantly change the relaxation pathways and excited state lifetimes and support the further investigation of light harvesting and photocatalytic applications of 3d transition metal complexes.

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

Science.gov (United States)

Maharjan, Rijan; Brown, Eric

2017-12-01

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

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

International Nuclear Information System (INIS)

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

1992-01-01

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

Self-organized profile relaxation by ion temperature gradient instability in toroidal plasmas

International Nuclear Information System (INIS)

Kishimoto, Y.; Tajima, T.; LeBrun, M.J.; Gray, M.G.; Kim, J.Y.; Horton, W.

1993-02-01

Toroidal effects on the ion-temperature gradient mode are found to dictate the temperature evolution and the subsequent relaxed profile realization according to our toroidal particle simulation. Both in the strongly unstable fluid regime as well as in the near-marginal kinetic regime we observe that the plasma maintains an exponential temperature profile and forces the heat flux to be radially independent. The self-organized critical relaxed state is sustained slightly above the marginal stability, where the weak wave growth balances the wave decorrelation

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.

Relaxed and partially relaxed magnetic equilibria in tight-aspect-ratio tori

International Nuclear Information System (INIS)

Browning, P.K.; Clegg, J.R.; Duck, R.C.; Rusbridge, M.G.

1993-01-01

Force-free equilibrium magnetic fields in tight-aspect-ratio toroidal configurations are investigated. The study is mainly directed to modelling field configurations in the 'rodomak', a modification to the SPHEX gun-injected spheromak in which a current-carrying rod is inserted along the geometric axis. A family of analytical relaxed states (∇ x B = μB, μ constant) is presented for a torus of rectangular cross section, with boundary conditions allowing for flux embedded in the walls, representing the gun. Numerically calculated fields in SPHEX geometry, with μ profiles relevant to the driven phase of operation, are also given. The dependence of the field configurations and global quantities such as energy, helicity and toroidal current on the controlling parameters (gun flux, gun current and rod current) and geometry is discussed. (author)

Increasing the effective energy barrier promoted by the change of a counteranion in a Zn-Dy-Zn SMM: slow relaxation via the second excited state.

Science.gov (United States)

Oyarzabal, I; Ruiz, J; Ruiz, E; Aravena, D; Seco, J M; Colacio, E

2015-08-11

The trinuclear complex [ZnCl(μ-L)Dy(μ-L)ClZn]PF6 exhibits a single-molecule magnetic behaviour under zero field with a relatively large effective energy barrier of 186 cm(-1). Ab initio calculations reveal that the relaxation of the magnetization is symmetry-driven (the Dy(III) ion possesses a C2 symmetry) and occurs via the second excited state.

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)

Dielectric relaxation studies of some primary alcohols and their mixture with water

International Nuclear Information System (INIS)

Ahmad, S.S.; Yaqub, M.

2003-01-01

The complex dielectric constant of ethyl alcohol, methyl alcohol and 1- propanol and their mixtures with water of different concentration, (0 to 100% by weight) at the temperature of 303K has been evaluated, within the frequency range of (100KHz- 100 MHz). Moreover, the viscosity mu of each alcohol and its mixture with water have been measured at this temperature. The dielectric properties have been evaluated by Hartshorn and Ward apparatus. The purpose of this work is to study the influence of aliphatic group, size and shape on the extent of hydrogen bonding and also to obtain the thermodynamic data on hydrogen bond formation in the pure liquid state and its mixture. The width of the semicircle plot determines the distribution of average relaxation time. Dielectric relaxation time in pure alcohols and their water mixture has been calculated from the respected Cole-Cole plot and dielectric data. A single relaxation time of 117.16ps has been obtained for the molecules of pure methanol, whereas, the dielectric data of prophyl alcohol which indicates the viscosity water have been measured at the temperature 303 K. The dielectric properties in distribution of relaxation time, which is in good agreement with the Davidson-cole representation. The molecules in liquid mixture within frequency range, the mixture has more than one relaxation item, leading to the shortening of main relaxation time as compared with the pure alcohol and broadening of the complex permitivity spectra. The dependence of the dielectric relaxation on composition shows a remarkable behavior. Results are discussed in the light of H-bonded molecules. (author)

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.

Muon spin relaxation in ferromagnetic PdMn

International Nuclear Information System (INIS)

Dodds, S.A.; Gist, G.A.; Heffner, R.H.; Leon, M.; MacLaughlin, D.E.; Mydosh, J.A.; Nieuwenhuys, G.J.; Schillaci, M.E.

1983-01-01

Positive-muon (μ + ) spin relaxation experiments have been carried out in the dilute ferromagnetic alloy Pd + 2 at % Mn (T/sub c/ = 5.8 0 K). In the paramagnetic state the inhomogeneous μ + linewidth is proportional to the bulk magnetization. Below T/sub c/ the μ + linewidth and the width of the μ + local field distribution in zero applied field are both in qualitative accord with the Sherrington-Kirkpatrick theory of disordered magnets

Muon spin relaxation in ferromagnetic PdMn

Energy Technology Data Exchange (ETDEWEB)

Dodds, S.A.; Gist, G.A. (Rice Univ., Houston, TX (USA)); Heffner, R.H.; Leon, M.; Schillaci, M.E. (Los Alamos National Lab., NM (USA)); MacLaughlin, D.E. (California Univ., Riverside (USA)); Mydosh, J.A.; Nieuwenhuys, G.J. (Rijksuniversiteit Leiden (Netherlands). Kamerlingh Onnes Lab.)

1984-01-01

Positive-muon (..mu../sup +/) spin relaxation experiments have been carried out in the dilute ferromagnetic alloy Pd + 2 at.% Mn (Tsub(c) = 5.8 K). In the paramagnetic state the inhomogeneous ..mu../sup +/ linewidth is proportional to the bulk magnetization. Below Tsub(c) the ..mu../sup +/ linewidth and the width of the ..mu../sup +/ local field distribution in zero applied field are both in qualitative accord with the Sherrington-Kirkpatrick theory of disordered magnets.

Analysis of GPS Satellite Allocation for the United States Nuclear Detonation Detection System (USNDS)

National Research Council Canada - National Science Library

Bell, Aaron

2002-01-01

...) satellites to detect atmospheric nuclear detonations. Though there are currently over 24 operational GPS satellites, USNDS ground based antennas are only capable of actively monitoring 24 satellites at a time...

Dynamical renormalization group approach to relaxation in quantum field theory

International Nuclear Information System (INIS)

Boyanovsky, D.; Vega, H.J. de

2003-01-01

The real time evolution and relaxation of expectation values of quantum fields and of quantum states are computed as initial value problems by implementing the dynamical renormalization group (DRG). Linear response is invoked to set up the renormalized initial value problem to study the dynamics of the expectation value of quantum fields. The perturbative solution of the equations of motion for the field expectation values of quantum fields as well as the evolution of quantum states features secular terms, namely terms that grow in time and invalidate the perturbative expansion for late times. The DRG provides a consistent framework to resum these secular terms and yields a uniform asymptotic expansion at long times. Several relevant cases are studied in detail, including those of threshold infrared divergences which appear in gauge theories at finite temperature and lead to anomalous relaxation. In these cases the DRG is shown to provide a resummation akin to Bloch-Nordsieck but directly in real time and that goes beyond the scope of Bloch-Nordsieck and Dyson resummations. The nature of the resummation program is discussed in several examples. The DRG provides a framework that is consistent, systematic, and easy to implement to study the non-equilibrium relaxational dynamics directly in real time that does not rely on the concept of quasiparticle widths

Energy equation for the analysis of magnetization relaxation to equilibrium

Energy Technology Data Exchange (ETDEWEB)

Bertotti, G. [IEN Galileo Ferraris, Materials Department, Strada delle Cacce, 91, I-10135 Torino (Italy)]. E-mail: bertotti@ien.it; Bonin, R. [Dipartimento di Fisica, Politecnico di Torino, I-10129 Torino (Italy); Magni, A. [IEN Galileo Ferraris, Materials Department, Strada delle Cacce, 91, I-10135 Torino (Italy); Mayergoyz, I.D. [Department of Electrical and Computer Engineering, University of Maryland, College Park, Maryland, 20742 (United States); Serpico, C. [Dipartimento di Ingegneria Elettrica, Universita di Napoli ' Federico II' , I-80125 Naples (Italy)

2005-02-01

Magnetization relaxation starting from a generic non-equilibrium state is analytically described. An equation for the energy decay is obtained. On this basis, an approximate expression for the magnetization motion during the ringing process is obtained in terms of Jacobi elliptic functions with time-dependent parameters.

Energy equation for the analysis of magnetization relaxation to equilibrium

International Nuclear Information System (INIS)

Bertotti, G.; Bonin, R.; Magni, A.; Mayergoyz, I.D.; Serpico, C.

2005-01-01

Magnetization relaxation starting from a generic non-equilibrium state is analytically described. An equation for the energy decay is obtained. On this basis, an approximate expression for the magnetization motion during the ringing process is obtained in terms of Jacobi elliptic functions with time-dependent parameters

Combining forest inventory, satellite remote sensing, and geospatial data for mapping forest attributes of the conterminous United States

Science.gov (United States)

Mark Nelson; Greg Liknes; Charles H. Perry

2009-01-01

Analysis and display of forest composition, structure, and pattern provides information for a variety of assessments and management decision support. The objective of this study was to produce geospatial datasets and maps of conterminous United States forest land ownership, forest site productivity, timberland, and reserved forest land. Satellite image-based maps of...

Magnetic relaxation behaviour in Pr_2NiSi_3

International Nuclear Information System (INIS)

Pakhira, Santanu; Mazumdar, Chandan; Ranganathan, R.

2016-01-01

Time dependent isothemal remanent magnetizatin (IRM) behaviour for polycrystalline compound Pr_2NiSi_3 have been studied below its characteristic temperature. The compound undergoes slow magnetic relaxation with time. Along with competing interaction, non-magnetic atom disorder plays an important role in formation of non-equilibrium glassy like ground state for this compound.

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

Directory of Open Access Journals (Sweden)

Fateme Shobeiri

2015-09-01

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

Study of the relaxation of electron velocity distributions in gases

Energy Technology Data Exchange (ETDEWEB)

Braglia, G L [Parma Univ. (Italy). Ist. di Fisica; Caraffini, G L; Diligenti, M [Parma Univ. (Italy). Ist. di Matematica

1981-03-11

The Fokker-Planck equation governing the relaxation of the electron speed (energy) distribution in gases is solved in a number of cases of special interest. The solution is given in terms of eigenfunctions of the Fokker-Planck operator, satisfying an orthonormalization condition in which the steady-state distribution is the weight function. The real cross-sections of the noble gases He, Ne, Ar, Kr and Xe, together with model collision frequencies of the form ..nu..(v) = ..cap alpha..vsup(n) with n = 0.5, 1, 1.5, 3 and 3.5, are used to calculate eigenvalues and eigenfunctions. The first fifteen eigenvalues are obtained in each case both in the absence and in the presence of a d.c. electric field and, in the latter case, both with atoms at rest and atoms in motion. Calculations of relaxation times and examples of evolutions towards their steady-state forms of given initial distributions are reported in several particular cases.

Relaxation rates of gene expression kinetics reveal the feedback signs of autoregulatory gene networks

Science.gov (United States)

Jia, Chen; Qian, Hong; Chen, Min; Zhang, Michael Q.

2018-03-01

The transient response to a stimulus and subsequent recovery to a steady state are the fundamental characteristics of a living organism. Here we study the relaxation kinetics of autoregulatory gene networks based on the chemical master equation model of single-cell stochastic gene expression with nonlinear feedback regulation. We report a novel relation between the rate of relaxation, characterized by the spectral gap of the Markov model, and the feedback sign of the underlying gene circuit. When a network has no feedback, the relaxation rate is exactly the decaying rate of the protein. We further show that positive feedback always slows down the relaxation kinetics while negative feedback always speeds it up. Numerical simulations demonstrate that this relation provides a possible method to infer the feedback topology of autoregulatory gene networks by using time-series data of gene expression.

Nonequilibrium relaxations within the ground-state manifold in the antiferromagnetic Ising model on a triangular lattice.

Science.gov (United States)

Kim, Eunhye; Lee, Sung Jong; Kim, Bongsoo

2007-02-01

We present an extensive Monte Carlo simulation study on the nonequilibrium kinetics of triangular antiferromagnetic Ising model within the ground state ensemble which consists of sectors, each of which is characterized by a unique value of the string density p through a dimer covering method. Building upon our recent work [Phys. Rev. E 68, 066127 (2003)] where we considered the nonequilibrium relaxation observed within the dominant sector with p=2/3, we here focus on the nonequilibrium kinetics within the minor sectors with psimple scaling behavior A(t)=A(t/tau(A)(p)), where the time scale tau(A)(p) shows a power-law divergence with vanishing p as tau(A)(p) approximately p(-phi) with phi approximately or equal to 4. These features can be understood in terms of random walk nature of the fluctuations of the strings within the typical separation between neighboring strings.

Satellite Communication and Long Distance Education

Directory of Open Access Journals (Sweden)

Hafied Cangara

2016-02-01

Full Text Available Since Indonesia introduced communication satellite for telecommunication network, the satellite has brought a number of advantages for national development in various areas, such as telephone network, mass media development, business, education, politics, security and national defence as well as regional and international cooperation. In education, satellite communication could be used for long-distance learning as implemented by 13 state universities in eastern parts of Indonesia. It is also possible to develop the Open University System in teaching and learning process, particularly since the internet technology has been intensively used

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)

Can We Efficiently Check Concurrent Programs Under Relaxed Memory Models in Maude?

DEFF Research Database (Denmark)

Arrahman, Yehia Abd; Andric, Marina; Beggiato, Alessandro

2014-01-01

to the state space explosion. Several techniques have been proposed to mitigate those problems so to make verification under relaxed memory models feasible. We discuss how to adopt some of those techniques in a Maude-based approach to language prototyping, and suggest the use of other techniques that have been......Relaxed memory models offer suitable abstractions of the actual optimizations offered by multi-core architectures and by compilers of concurrent programming languages. Using such abstractions for verification purposes is challenging in part due to their inherent non-determinism which contributes...

Analysis of data collected by the Tatyana II satellite

International Nuclear Information System (INIS)

Rivera, Lilianaa; Mendoza-Torres, Eduardo; Martinez, Oscar; Salazar, Humberto

2011-01-01

The Tatyana II satellite is the second one of the University Satellite Program, which is led by the Moscow State University with the participation of the Benemerita Universidad Autonoma de Puebla. This satellite has ultraviolet, red-infrared and charged particles detectors. In this work preliminary results based on the data collected by these detectors on board the satellite over a period of ∼3.5 months are presented.

Tightness of Semidefinite Programming Relaxation to Robust Transmit Beamforming with SINR Constraints

Directory of Open Access Journals (Sweden)

Yanjun Wang

2013-01-01

Full Text Available This paper considers a multiuser transmit beamforming problem under uncertain channel state information (CSI subject to SINR constraints in a downlink multiuser MISO system. A robust transmit beamforming formulation is proposed. This robust formulation is to minimize the transmission power subject to worst-case signal-to-interference-plus-noise ratio (SINR constraints on the receivers. The challenging problem is that the worst-case SINR constraints correspond to an infinite number of nonconvex quadratic constraints. In this paper, a natural semidifinite programming (SDP relaxation problem is proposed to solve the robust beamforming problem. The main contribution of this paper is to establish the tightness of the SDP relaxation problem under proper assumption, which means that the SDP relaxation problem definitely yields rank-one solutions under the assumption. Then the SDP relaxation problem provides globally optimum solutions of the primal robust transmit beamforming problem under proper assumption and norm-constrained CSI errors. Simulation results show the correctness of the proposed theoretical results and also provide a counterexample whose solutions are not rank one. The existence of counterexample shows that the guess that the solutions of the SDP relaxation problem must be rank one is wrong, except that some assumptions (such as the one proposed in this paper hold.

Stress relaxation in quasi-two-dimensional self-assembled nanoparticle monolayers

Science.gov (United States)

Boucheron, Leandra S.; Stanley, Jacob T.; Dai, Yeling; You, Siheng Sean; Parzyck, Christopher T.; Narayanan, Suresh; Sandy, Alec R.; Jiang, Zhang; Meron, Mati; Lin, Binhua; Shpyrko, Oleg G.

2018-05-01

We experimentally probed the stress relaxation of a monolayer of iron oxide nanoparticles at the water-air interface. Upon drop-casting onto a water surface, the nanoparticles self-assembled into islands of two-dimensional hexagonally close packed crystalline domains surrounded by large voids. When compressed laterally, the voids gradually disappeared as the surface pressure increased. After the compression was stopped, the surface pressure (as measured by a Wilhelmy plate) evolved as a function of the film aging time with three distinct timescales. These aging dynamics were intrinsic to the stressed state built up during the non-equilibrium compression of the film. Utilizing x-ray photon correlation spectroscopy, we measured the characteristic relaxation time (τ ) of in-plane nanoparticle motion as a function of the aging time through both second-order and two-time autocorrelation analysis. Compressed and stretched exponential fitting of the intermediate scattering function yielded exponents (β ) indicating different relaxation mechanisms of the films under different compression stresses. For a monolayer compressed to a lower surface pressure (between 20 mN/m and 30 mN/m), the relaxation time (τ ) decreased continuously as a function of the aging time, as did the fitted exponent, which transitioned from being compressed (>1 ) to stretched (stress release through crystalline domain reorganization. However, for a monolayer compressed to a higher surface pressure (around 40 mN/m), the relaxation time increased continuously and the compressed exponent varied very little from a value of 1.6, suggesting that the system may have been highly stressed and jammed. Despite the interesting stress relaxation signatures seen in these samples, the structural ordering of the monolayer remained the same over the sample lifetime, as revealed by grazing incidence x-ray diffraction.

Singlet and triplet polaron relaxation in doubly charged self-assembled quantum dots

International Nuclear Information System (INIS)

Grange, T; Zibik, E A; Ferreira, R; Bastard, G; Carpenter, B A; Phillips, P J; Stehr, D; Winnerl, S; Helm, M; Steer, M J; Hopkinson, M; Cockburn, J W; Skolnick, M S; Wilson, L R

2007-01-01

Polaron relaxation in self-assembled InAs/GaAs quantum dot samples containing 2 electrons per dot is studied using far-infrared, time-resolved pump-probe measurements for transitions between the s-like ground and p-like first excited conduction band states. Spin-flip transitions between singlet and triplet states are observed experimentally in the decay of the absorption bleaching, which shows a clear biexponential dependence. The initial fast decay (∼30 ps) is associated with the singlet polaron decay, while the decay component with the longer time constant (∼5 ns) corresponds to the excited state triplet lifetime. The results are explained by considering the intrinsic Dresselhaus spin-orbit interaction, which induces spin-flip transitions by acoustic phonon emission or phonon anharmonicity. We have calculated the spin-flip decay times, and good agreement is obtained between the experiment and the simulation of the pump-probe signal. Our results demonstrate the importance of spin-mixing effects for intraband energy relaxation in InAs/GaAs quantum dots

Sun glitter imaging of submarine sand waves on the Taiwan Banks: Determination of the relaxation rate of short waves

Science.gov (United States)

Shao, Hao; Li, Yan; Li, Li

2011-06-01

Above sand waves on the seafloor, surface short waves, which are responsible for the radiance distribution in remote sensing imagery, are modulated gradually by the submarine topography. The relaxation rate μr characterizes the rate at which the short waves reach their saturation range after being disturbed. It is a key parameter in the weak hydrodynamic interaction theory and is also a most important parameter in the imaging mechanism used for mapping submarine bottom topography. In this study, a robust expression containing intensity and phase (advection effect) modulations of the perturbed action spectrum of short waves was deduced, by using the first-order weak hydrodynamic interaction theory. On the basis of the phase modulation, a method was developed to determine the relaxation rate in the Sun glitter imaging mechanism. The relaxation rates were estimated using in situ data measured on a cruise over the sand waves of the Taiwan Banks, a sea area between the East China Sea and the South China Sea, on 28-29 August 2006. Results showed that, under a wind speed of 5.0 m s-1, the relaxation rate of short waves was about 0.055 s-1 in response to current variations and about 0.025 s-1 equivalently in response to sea bottom topographic variations. The former value could be applied to interpret the amplitude of submarine topography by using satellite imagery, while the latter one (equivalent relaxation rate μ'r) could help to more accurately calibrate the spatial position of the retrieved sea bottom topography.

Spin-Relaxation Anisotropy in a GaAs Quantum Dot

NARCIS (Netherlands)

Scarlino, P.; Kawakami, E.; Stano, P.; Shafiei, M.; Reichl, C.; Wegscheider, W.; Vandersypen, L.M.K.

2014-01-01

We report that the electron spin-relaxation time T1 in a GaAs quantum dot with a spin-1/2 ground state has a 180° periodicity in the orientation of the in-plane magnetic field. This periodicity has been predicted for circular dots as being due to the interplay of Rashba and Dresselhaus spin orbit

Influence of relaxation times on the Bloch-Siegert shift

International Nuclear Information System (INIS)

Cao Long Van

1981-01-01

A new method for calculations of Bloch-Siegert shifts in resonances between excited states with the inclusion of relaxation times is given. It will be shown that in this case the definition of the resonance given by I. Bialynicka-Birula is in agreement with the criterion defining the resonance used by D.A. Andrews and G. Newton. (author)

Relaxation dynamics and coherent energy exchange in coupled vibration-cavity polaritons (Conference Presentation)

Science.gov (United States)

Simpkins, Blake S.; Fears, Kenan P.; Dressick, Walter J.; Dunkelberger, Adam D.; Spann, Bryan T.; Owrutsky, Jeffrey C.

2016-09-01

Coherent coupling between an optical transition and confined optical mode have been investigated for electronic-state transitions, however, only very recently have vibrational transitions been considered. Here, we demonstrate both static and dynamic results for vibrational bands strongly coupled to optical cavities. We experimentally and numerically describe strong coupling between a Fabry-Pérot cavity and carbonyl stretch ( 1730 cm 1) in poly-methylmethacrylate and provide evidence that the mixed-states are immune to inhomogeneous broadening. We investigate strong and weak coupling regimes through examination of cavities loaded with varying concentrations of a urethane monomer. Rabi splittings are in excellent agreement with an analytical description using no fitting parameters. Ultrafast pump-probe measurements reveal transient absorption signals over a frequency range well-separated from the vibrational band, as well as drastically modified relaxation rates. We speculate these modified kinetics are a consequence of the energy proximity between the vibration-cavity polariton modes and excited state transitions and that polaritons offer an alternative relaxation path for vibrational excitations. Varying the polariton energies by angle-tuning yields transient results consistent with this hypothesis. Furthermore, Rabi oscillations, or quantum beats, are observed at early times and we see evidence that these coherent vibration-cavity polariton excitations impact excited state population through cavity losses. Together, these results indicate that cavity coupling may be used to influence both excitation and relaxation rates of vibrations. Opening the field of polaritonic coupling to vibrational species promises to be a rich arena amenable to a wide variety of infrared-active bonds that can be studied in steady state and dynamically.

Commercial Satellite Imagery Analysis for Countering Nuclear Proliferation

Science.gov (United States)

Albright, David; Burkhard, Sarah; Lach, Allison

2018-05-01

High-resolution commercial satellite imagery from a growing number of private satellite companies allows nongovernmental analysts to better understand secret or opaque nuclear programs of countries in unstable or tense regions, called proliferant states. They include North Korea, Iran, India, Pakistan, and Israel. By using imagery to make these countries’ aims and capabilities more transparent, nongovernmental groups like the Institute for Science and International Security have affected the policies of governments and the course of public debate. Satellite imagery work has also strengthened the efforts of the International Atomic Energy Agency, thereby helping this key international agency build its case to mount inspections of suspect sites and activities. This work has improved assessments of the nuclear capabilities of proliferant states. Several case studies provide insight into the use of commercial satellite imagery as a key tool to educate policy makers and affect policy.

Can relaxation interventions reduce anxiety in patients receiving radiotherapy? outcomes and study validity

International Nuclear Information System (INIS)

Elith, C.A.; Perkins, B.A.; Johnson, L.S.; Skelly, M.H.; Dempsey, S.

2001-01-01

This study piloted the use of three relaxation interventions in an attempt to reduce levels of anxiety in patients who are immobilised for radiotherapy treatment of head and neck cancers, as well as trying to validate the study methodology. In addition to receiving normal radiation therapy treatment, 14 patients were assigned to either a control group not receiving the relaxation intervention or one of three validated relaxation intervention techniques; music therapy, aromatherapy or guided imagery. Patients in the intervention groups underwent the relaxation technique daily for the first seven days of treatment. On days 1, 3, 5 and 7 of treatment patients were required to complete the State Anxiety Inventory survey. While caution should be taken in accepting the results due to the small numbers of patients involved in the study and the non-randomised assignment of patients within the study, the results of the study demonstrate a clinically significant reduction in anxiety levels in each of the three relaxation interventions compared to the control group. The study demonstrated good study validity due to the ease of implementation, the unambiguous results generated, and the use of already validated anxiety intersections and measurement tools. Copyright (2001) Australian Institute of Radiography

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.

The YORP effect on the GOES 8 and GOES 10 satellites: A case study

Science.gov (United States)

Albuja, Antonella A.; Scheeres, Daniel J.; Cognion, Rita L.; Ryan, William; Ryan, Eileen V.

2018-01-01

The Yarkovsky-O'Keefe-Radzievskii-Paddack (YORP) effect is a proposed explanation for the observed rotation behavior of inactive satellites in Earth orbit. This paper further explores the YORP effect for highly asymmetric inactive satellites. Satellite models are developed to represent the GOES 8 and GOES 10 satellites, both of which are currently inactive in geosynchronous Earth orbit (GEO). A simple satellite model for the GOES 8 satellite is used to analyze the short period variations of the angular velocity and obliquity as a result of the YORP effect. A more complex model for the rotational dynamics of the GOES 8 and GOES 10 satellites are developed to probe their sensitivity and to match observed spin periods and states of these satellites. The simulated rotation periods are compared to observations for both satellites. The comparison between YORP theory and observed rotation rates for both satellites show that the YORP effect could be the cause for the observed rotational behavior. The YORP model also predicts a novel state for the GOES 8 satellite, namely that it could periodically fall into a tumbling rotation state. Recent observations of this satellite are consistent with this prediction.

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 ...

Deducting the temperature dependence of the structural relaxation time in equilibrium far below the nominal Tg by aging the decoupled conductivity relaxation to equilibrium.

Science.gov (United States)

Wojnarowska, Z; Ngai, K L; Paluch, M

2014-05-07

Using broadband dielectric spectroscopy we investigate the changes in the conductivity relaxation times τσ observed during the physical aging of the protic ionic conductor carvedilol dihydrogen phosphate (CP). Due to the large decoupling of ion diffusion from host molecule reorientation, the ion conductivity relaxation time τσ(Tage,tage) can be directly measured at temperatures Tage below Tg for exceedingly long aging times tage till τσ(Tage,tage) has reached the equilibrium value τσ(eq)(Tage). The dependence of τσ(Tage,tage) on tage is well described by the stretched exponential function, τσ(Tage, tage) = Aexp[-((tage)/(τage(Tage)))(β)] + τσ(eq)(Tage), where β is a constant and τage(Tage) can be taken as the structural α-relaxation time of the equilibrium liquid at T = Tage. The value of τσ(eq)(Tage) obtained after 63 days long annealing of CP, deviates from the Vogel-Fulcher-Tammann-Hesse (VFTHσ) dependence of τσ(T) determined from data taken above Tg and extrapolated down to Tage. Concurrently, τage(Tage) also deviates from the Vogel-Fulcher-Tammann-Hesse (VFTHα) dependence. The results help to answer the longstanding question of whether the VFTH dependence of τσ(T) as well as the structural α-relaxation time τα(T) holds or not in the equilibrium liquid state far below Tg.

Relaxation therapy and anxiety, self-esteem, and emotional regulation among adults with intellectual disabilities: A randomized controlled trial.

Science.gov (United States)

Bouvet, Cyrille; Coulet, Aurélie

2016-09-01

This pilot study is a randomized controlled trial on the effects of relaxation on anxiety, self-esteem, and emotional regulation in adults with intellectual disabilities (ID) working in a center of supported employment in France. We studied 30 adults with mild or moderate ID who were split at random into a relaxation group (RG, 15 subjects), who completed 10 sessions of relaxation therapy, and a control group (CG, 15 subjects), who were on a waiting list. The method used is the pretest and posttest. Variables were assessed by the State-Trait Anxiety Inventory form Y scale, the Rosenberg Self-Esteem scale, and the Emotion Regulation Questionnaire. We found that in the RG, relaxation significantly reduced state anxiety, t(14, 15) = 17.8***, d = -0.72, and improved self-esteem, t(14, 15) = -7.7***, d = 1.03, and cognitive reappraisal, t(14, 15) = -6.3***, d = 1.3, while the CG showed no change for these variables. We conclude that relaxation seems to be an interesting therapeutic option for reducing anxiety in people with ID in a supported employment setting. © The Author(s) 2015.

Experimental evidence for simultaneous relaxation processes in super spin glass γ-Fe2O3 nanoparticle system

Science.gov (United States)

Nikolic, V.; Perovic, M.; Kusigerski, V.; Boskovic, M.; Mrakovic, A.; Blanusa, J.; Spasojevic, V.

2015-03-01

Spherical γ-Fe2O3 nanoparticles with the narrow size distribution of (5 ± 1) nm were synthesized by the method of thermal decomposition from iron acetyl acetonate precursor. The existence of super spin-glass state at low temperatures and in low applied magnetic fields was confirmed by DC magnetization measurements on a SQUID magnetometer. The comprehensive investigation of magnetic relaxation dynamics in low-temperature region was conducted through the measurements of single-stop and multiple stop ZFC memory effects, ZFC magnetization relaxation, and AC susceptibility measurements. The experimental findings revealed the peculiar change of magnetic relaxation dynamics at T ≈ 10 K, which arose as a consequence of simultaneous existence of different relaxation processes in Fe2O3 nanoparticle system. Complementarity of the applied measurements was utilized in order to single out distinct relaxation processes as well as to elucidate complex relaxation mechanisms in the investigated interacting nanoparticle system.

Composite Analysis of Concrete - Creep, Relaxation and Eigenstrain/stress

DEFF Research Database (Denmark)

Nielsen, Lauge Fuglsang

1996-01-01

approach.The model is successfully justified comparing predicted results with recent experimental data obtained in tests made at the Danish Technological Institute and at the Technical University of Denmark on creep, relaxation, and shrinkage of very young concretes (hours) - and also with experimental...... results on creep, shrinkage, and internal stresses caused by drying shrinkage reported in the literature on the mechanical behavior of mature concretes.Shrinkage (autogeneous or drying) of mortar and concrete and associated internal stress states are examples of analysis made in this report......A composite-rheological model of concrete is presented by which consistent predictions of creep, relaxation, and internal stresses can be made from known concrete composition, age at loading, and climatic conditions. No other existing "creep prediction method" offers these possibilities in one...

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.

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

Stability of (Fe-Tm-B) amorphous alloys: relaxation and crystallization phenomena

International Nuclear Information System (INIS)

Zemcik, T.

1994-01-01

Fe-Tm-B base (TM = transition metal) amorphous alloys (metallic glasses) are thermodynamically metastable. This limits their use as otherwise favourable materials, e.g. magnetically soft, corrosion resistant and mechanically firm. By analogy of the mechanical strain-stress dependence, at a certain degree of thermal activation the amorphous structure reaches its limiting state where it changes its character and physical properties. Relaxation and early crystallization processes in amorphous alloys, starting already around 100 C, are reviewed involving subsequently stress relief, free volume shrinking, topological and chemical ordering, pre-crystallization phenomena up to partial (primary) crystallization. Two diametrically different examples are demonstrated from among the soft magnetic materials: relaxation and early crystallization processes in the Fe-Co-B metallic glasses and controlled crystallization of amorphous ribbons yielding rather modern nanocrystalline ''Finemet'' alloys where late relaxation and pre-crystallization phenomena overlap when forming extremely dispersive and fine-grained nanocrystals-in-amorphous-sauce structure. Moessbauer spectroscopy seems to be unique for magnetic and phase analysis of such complicated systems. (orig.)

Zeeman relaxation of MnH (X7Σ+) in collisions with 3He: Mechanism and comparison with experiment

International Nuclear Information System (INIS)

Turpin, F.; Stoecklin, T.; Halvick, Ph.

2011-01-01

We present a theoretical study of the Zeeman relaxation of the magnetically trappable lowest field seeking state of MnH ( 7 Σ) in collisions with 3 He. We analyze the collisional Zeeman transition mechanism as a function of the final diatomic state and its variation as a function of an applied magnetic field. We show that as a result of this mechanism the levels with ΔM j >2 give negligible contributions to the Zeemam relaxation cross section. We also compare our results to the experimental cross sections obtained from the buffer-gas cooling and magnetic trapping of this molecule and investigate the dependence of the Zeeman relaxation cross section on the accuracy of the three-body interaction at ultralow energies.

Zeeman relaxation of MnH (X7Σ+) in collisions with He3: Mechanism and comparison with experiment

Science.gov (United States)

Turpin, F.; Stoecklin, T.; Halvick, Ph.

2011-03-01

We present a theoretical study of the Zeeman relaxation of the magnetically trappable lowest field seeking state of MnH (7Σ) in collisions with He3. We analyze the collisional Zeeman transition mechanism as a function of the final diatomic state and its variation as a function of an applied magnetic field. We show that as a result of this mechanism the levels with ΔMj>2 give negligible contributions to the Zeemam relaxation cross section. We also compare our results to the experimental cross sections obtained from the buffer-gas cooling and magnetic trapping of this molecule and investigate the dependence of the Zeeman relaxation cross section on the accuracy of the three-body interaction at ultralow energies.

One and two-phonon processes of the spin-flip relaxation in quantum dots: Spin-phonon coupling mechanism

Science.gov (United States)

Wang, Zi-Wu; Li, Shu-Shen

2012-07-01

We investigate the spin-flip relaxation in quantum dots using a non-radiation transition approach based on the descriptions for the electron-phonon deformation potential and Fröhlich interaction in the Pavlov-Firsov spin-phonon Hamiltonian. We give the comparisons of the electron relaxations with and without spin-flip assisted by one and two-phonon processes. Calculations are performed for the dependence of the relaxation time on the external magnetic field, the temperature and the energy separation between the Zeeman sublevels of the ground and first-excited state. We find that the electron relaxation time of the spin-flip process is more longer by three orders of magnitudes than that of no spin-flip process.

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

Stretched exponential relaxation in molecular and electronic glasses

Science.gov (United States)

Phillips, J. C.

1996-09-01

der Waals supercooled liquids and glasses, orientational glasses, water, fused salts, and heme proteins. In the intrinsic cases the theory of 0034-4885/59/9/003/img5 is often accurate to 2%, which is often better than the quoted experimental accuracies 0034-4885/59/9/003/img12. The extrinsic cases are identified by explicit structural signatures which are discussed at length. The discussion also includes recent molecular dynamical simulations for metallic glasses, spin glasses, quasicrystals and polymers which have achieved the intermediate relaxed Kohlrausch state and which have obtained values of 0034-4885/59/9/003/img2 in excellent agreement with the prediction of the microscopic theory.

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.

Adiabatic fast passage application in solid state NMR study of cross relaxation and molecular dynamics in heteronuclear systems.

Science.gov (United States)

Baranowski, M; Woźniak-Braszak, A; Jurga, K

2016-01-01

The paper presents the benefits of using fast adiabatic passage for the study of molecular dynamics in the solid state heteronuclear systems in the laboratory frame. A homemade pulse spectrometer operating at the frequency of 30.2MHz and 28.411MHz for protons and fluorines, respectively, has been enhanced with microcontroller direct digital synthesizer DDS controller [1-4]. This work briefly describes how to construct a low-cost and easy-to-assemble adiabatic extension set for homemade and commercial spectrometers based on recently very popular Arduino shields. The described set was designed for fast adiabatic generation. Timing and synchronization problems are discussed. The cross-relaxation experiments with different initial states of the two spin systems have been performed. Contrary to our previous work [5] where the steady-state NOE experiments were conducted now proton spins (1)H are polarized in the magnetic field B0 while fluorine spins (19)F are perturbed by selective saturation for a short time and then the system is allowed to evolve for a period in the absence of a saturating field. The adiabatic passage application leads to a reversal of magnetization of fluorine spins and increases the amplitude of the signal. Copyright © 2015 Elsevier Inc. All rights reserved.

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.

The study of magnetic properties and relaxation processes in Co/Au bimetallic nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Hrubovčák, Pavol [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňáková, Adriana, E-mail: adriana.zelenakova@upjs.sk [Department of Condensed Matter Physics, P.J. Šafárik University, Park Angelinum 9, Košice (Slovakia); Zeleňák, Vladimir [Department of Inorganic Chemistry, P.J. Šafárik University, Moyzesova 11, Košice (Slovakia); Kováč, Jozef [Institute of Experimental Physics, SAS, Watsonova 41, Košice (Slovakia)

2015-11-15

Co/Au bimetallic fine nanoparticles were prepared employing the method of microemulsion using reverse micelle as nanoreactor, controlling the particles size. Magnetic and structural properties of two different samples Co/Au1 and Co/Au2 with almost comparable size of Co core and different size of Au layer were studied. The investigation of magnetic relaxation processes present in the particles was carried out by means of ac and dc magnetization data obtained at different temperatures and magnitudes of magnetic field. We observed the existence of superspin glass state characterized by the strong inter-particle interactions in the nanoparticle systems. In this paper, we discuss the attributes of novel superspin glass magnetic state reflected on various features (saturated FC magnetization at low temperatures, shift of the Cole–Cole arc downwards) and calculated parameters (relaxation time, critical exponent zv ∼ 10 and frequency dependent criterion p < 0.05). Comparison of the magnetic properties of two studied samples show that the thickness of diamagnetic Au shell significantly influences the magnetic interactions and change the relaxation dynamics. - Highlights: • Co/Au fine nanoparticles prepared by reverse micelle as nanoreactor, controlling the size. • Existence of superspin glass state confirmed from ac magnetic susceptibility study. • Individual particles exhibit the collective behavior below glass temperature T{sub SSG}. • Influence of diamagnetic shell on the magnetic properties of core–shell nanoparticles.

Improved optical properties of InAs quantum dots for intermediate band solar cells by suppression of misfit strain relaxation

Energy Technology Data Exchange (ETDEWEB)

Xie, H. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); School for Engineering of Matter, Transport, and Energy, Arizona State University, Tempe, Arizona 85287-6106 (United States); Prioli, R. [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Departamento de Física, Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro 22452-900 RJ (Brazil); Fischer, A. M.; Ponce, F. A., E-mail: ponce@asu.edu [Department of Physics, Arizona State University, Tempe, Arizona 85287-1504 (United States); Kawabata, R. M. S.; Pinto, L. D.; Souza, P. L. [LabSem, CETUC, Pontificia Universidade Católica do Rio de Janeiro, Marques de São Vicente 225, Rio de Janeiro 22452-900 RJ (Brazil); Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Jakomin, R. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Campus de Xerem, UFRJ, Duque de Caxias-RJ (Brazil); Pires, M. P. [Instituto Nacional de Ciência e Tecnologia de Nanodispositivos Semicondutores – DISSE – PUC-Rio, RJ (Brazil); Instituto de Física, UFRJ, Rio de Janeiro-RJ (Brazil)

2016-07-21

The properties of InAs quantum dots (QDs) have been studied for application in intermediate band solar cells. It is found that suppression of plastic relaxation in the QDs has a significant effect on the optoelectronic properties. Partial capping plus annealing is shown to be effective in controlling the height of the QDs and in suppressing plastic relaxation. A force balancing model is used to explain the relationship between plastic relaxation and QD height. A strong luminescence has been observed from strained QDs, indicating the presence of localized states in the desired energy range. No luminescence has been observed from plastically relaxed QDs.

Long Spin-Relaxation Times in a Transition-Metal Atom in Direct Contact to a Metal Substrate.

Science.gov (United States)

Hermenau, Jan; Ternes, Markus; Steinbrecher, Manuel; Wiesendanger, Roland; Wiebe, Jens

2018-03-14

Long spin-relaxation times are a prerequisite for the use of spins in data storage or nanospintronics technologies. An atomic-scale solid-state realization of such a system is the spin of a transition-metal atom adsorbed on a suitable substrate. For the case of a metallic substrate, which enables the direct addressing of the spin by conduction electrons, the experimentally measured lifetimes reported to date are on the order of only hundreds of femtoseconds. Here, we show that the spin states of iron atoms adsorbed directly on a conductive platinum substrate have a surprisingly long spin-relaxation time in the nanosecond regime, which is comparable to that of a transition metal atom decoupled from the substrate electrons by a thin decoupling layer. The combination of long spin-relaxation times and strong coupling to conduction electrons implies the possibility to use flexible coupling schemes to process the spin information.

Glass transition and relaxation processes of polymers studied by positron annihilation

Energy Technology Data Exchange (ETDEWEB)

Uedono, Akira; Tanigawa, Shoichiro [Tsukuba Univ., Ibaraki (Japan). Inst. of Materials Science

1996-10-01

The glass transition and relaxation processes of polymers were studied by the positron annihilation technique. A positron implanted into polymers might annihilate from positronium (Ps) states in open spaces. Ps is a bound state between a positron and an electron, and its nonrelativistic quantum mechanics is practically identical to that of a hydrogen atom. The lifetime of Ps can be associated with the size of the open spaces, and the formation probability of Ps provides information of motions of molecules. Since the glass transition or relaxation processes affect behavior of open spaces, one can study these phenomena through the detection of the open spaces using the positron annihilation technique. In the present paper, we report studies of the glass transition and relaxation processes in polyethylene, polypropylene, and polystyrene by measurements of lifetime spectra of positrons and those of Doppler broadening profiles of the annihilation radiation. For these specimens, by measurements of the lifetime of Ps, {tau}{sub 3}, as a function of temperature, the glass transition temperature, T{sub g}, was determined as an onset temperature of the increase in the temperature coefficient of {tau}{sub 3}. Below T{sub g}, local motions of molecules were detected by measurements of the formation probability of Ps. The positron annihilation as a tool for the characterization of polymers was discussed. (author). 51 refs.

Transient thermal and nonthermal electron and phonon relaxation after short-pulsed laser heating of metals

International Nuclear Information System (INIS)

Giri, Ashutosh; Hopkins, Patrick E.

2015-01-01

Several dynamic thermal and nonthermal scattering processes affect ultrafast heat transfer in metals after short-pulsed laser heating. Even with decades of measurements of electron-phonon relaxation, the role of thermal vs. nonthermal electron and phonon scattering on overall electron energy transfer to the phonons remains unclear. In this work, we derive an analytical expression for the electron-phonon coupling factor in a metal that includes contributions from equilibrium and nonequilibrium distributions of electrons. While the contribution from the nonthermal electrons to electron-phonon coupling is non-negligible, the increase in the electron relaxation rates with increasing laser fluence measured by thermoreflectance techniques cannot be accounted for by only considering electron-phonon relaxations. We conclude that electron-electron scattering along with electron-phonon scattering have to be considered simultaneously to correctly predict the transient nature of electron relaxation during and after short-pulsed heating of metals at elevated electron temperatures. Furthermore, for high electron temperature perturbations achieved at high absorbed laser fluences, we show good agreement between our model, which accounts for d-band excitations, and previous experimental data. Our model can be extended to other free electron metals with the knowledge of the density of states of electrons in the metals and considering electronic excitations from non-Fermi surface states

Relaxational dissipation of magnetic field energy in a rarefied plasma

International Nuclear Information System (INIS)

Vekshtejn, G.E.

1987-01-01

A mechanism of solar corona plasma heating connected with relaxation of a magnetic configuration in the corona to the state of the magnetic energy minimum at restrictions imposed by high conductivity of a medium is considered. Photospheric plasma pulsations leading to generation of longitudinal currents in the corona are in this case energy sources. The excess magnetic energy of these currents is dissipated as a result of reclosing of force lines of the magnetic field in narrow current layers. Plasmaturbulence related to the process of magnetic reclosing is phenomenologically described in this case by introducing certain characteristic time of relaxation. Such an approach permits to relate the plasma heating energy with parameters of photospheric motions in the framework of a simple model of the magnetic field

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.

The non-exponential relaxation of the C60 crystal around glass transition temperature

International Nuclear Information System (INIS)

Yan, F; Wang, Y.N.

1999-01-01

A model of the energy barrier of a molecule between two orientational states in the C 60 crystal, which depends on the neighboring molecules, is first proposed. Based on this model, the orientational relaxation of C 60 molecules around 90 K was simulated with the Monte Carlo method. The simulation results show that the relaxation is slightly non-exponential and can fit the Kohlrausch-Williams-Watts function with the non-exponential factor β = 0.962 ± 0.002, which is equal to the experimental data that has not been explained before. (orig.)

31-P Relaxation times of metabolic compounds in tumors grafted in nude mice

International Nuclear Information System (INIS)

Remy, C.; Benabid, A.L.; Jacrot, M.; Riondel, J.; Albrand, J.P.; Decorps, M.

1985-08-01

The observation that water proton relaxation rates were longer in tumors than in normal tissues provided a basis for the detection of human tumors by the NMR imaging technique. To evaluate the potentiality of 31-P NMR spectroscopy as a diagnostic tool of the pathological state of tissues, T1 and T2 relaxation times have been measured for the phosphates of ATP, inorganic phosphate (Pi), phosphomonoesters (PME) and phosphocreatine (PCr) in the 31-P NMR spectra obtained in vivo for normal rat brain and rat brain tumors implanted in nude mice

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.

Nuclear spin-lattice relaxation in n -type insulating and metallic GaAs single crystals

Science.gov (United States)

Lu, J.; Hoch, M. J. R.; Kuhns, P. L.; Moulton, W. G.; Gan, Z.; Reyes, A. P.

2006-09-01

The coupling of electron and nuclear spins in n-GaAs changes significantly as the donor concentration n increases through the insulator-metal critical concentration nC˜1.2×1016cm-3 . The present measurements of the Ga71 relaxation rates W made as a function of magnetic field (1-13T) and temperature (1.5-300K) for semi-insulating GaAs and for three doped n-GaAs samples with donor concentrations n=5.9×1015 , 7×1016 , and 2×1018cm-3 , show marked changes in the relaxation behavior with n . Korringa-like relaxation is found in both metallic samples for T30K phonon-induced nuclear quadrupolar relaxation is dominant. The relaxation rate measurements permit determination of the electron probability density at Ga71 sites. A small Knight shift of -3.3ppm was measured on the most metallic (2×1018cm-3) sample using magic-angle spinning at room temperature. For the n=5.9×1015cm-3 sample, a nuclear relaxation model involving the Fermi contact hyperfine interaction, rapid spin diffusion, and exchange coupled local moments is proposed. While the relaxation rate behavior with temperature for the weakly metallic sample, n=7×1016cm-3 , is similar to that found for the just-insulating sample, the magnetic field dependence is quite different. For the 5.9×1015cm-3 sample, increasing the magnetic field leads to a decrease in the relaxation rate, while for the 7×1016cm-3 sample this results in an increase in the relaxation rate ascribed to an increase in the density of states at the Fermi level as the Landau level degeneracy is increased.

Dynamics of merging: post-merger mixing and relaxation of an Illustris galaxy

Science.gov (United States)

Young, Anthony M.; Williams, Liliya L. R.; Hjorth, Jens

2018-02-01

During the merger of two galaxies, the resulting system undergoes violent relaxation and seeks stable equilibrium. However, the details of this evolution are not fully understood. Using Illustris simulation, we probe two physically related processes, mixing and relaxation. Though the two are driven by the same dynamics—global time-varying potential for the energy, and torques caused by asymmetries for angular momentum—we measure them differently. We define mixing as the redistribution of energy and angular momentum between particles of the two merging galaxies. We assess the degree of mixing as the difference between the shapes of their energy distributions, N(E)s, and their angular momentum distributions, N(L2)s. We find that the difference is decreasing with time, indicating mixing. To measure relaxation, we compare N(E) of the newly merged system to N(E) of a theoretical prediction for relaxed collisionless systems, DARKexp, and witness the system becoming more relaxed, in the sense that N(E) approaches DARKexp N(E). Because the dynamics driving mixing and relaxation are the same, the timescale is similar for both. We measure two sequential timescales: a rapid, 1 Gyr phase after the initial merger, during which the difference in N(E) of the two merging halos decreases by ~ 80%, followed by a slow phase, when the difference decreases by ~ 50% over ~ 8.5 Gyrs. This is a direct measurement of the relaxation timescale. Our work also draws attention to the fact that when a galaxy has reached Jeans equilibrium it may not yet have reached a fully relaxed state given by DARKexp, in that it retains information about its past history. This manifests itself most strongly in stars being centrally concentrated. We argue that it is particularly difficult for stars, and other tightly bound particles, to mix because they have less time to be influenced by the fluctuating potential, even across multiple merger events.

Time-Zone-Pattern Satellite Broadcasting Antenna

Science.gov (United States)

Galindo, Victor; Rahmat-Samii, Yahya; Imbriale, William A.; Cohen, Herb; Cagnon, Ronald R.

1988-01-01

Direct-broadcast satellite antenna designs provide contoured beams to match four time zones in 48 contiguous states and spot beams for Alaska, Hawaii, and Puerto Rico presented in 29-page report. Includes descriptions of procedures used to arrive at optimized designs. Arrangements, amplitudes, and phases of antenna feeds presented in tables. Gain contours shown graphically. Additional tables of performance data given for cities in service area of Eastern satellite.

Transverse magnetic field effects on the relaxation time of the magnetization in Mn12 measured by 55Mn-NMR

International Nuclear Information System (INIS)

Furukawa, Y.; Watanabe, K.; Kumagai, K.; Borsa, F.; Gatteschi, D.

2003-01-01

The longitudinal (H Z ) and transverse (H T ) magnetic field dependence of the relaxation time of the magnetization in Mn12 in its S=10 ground state was measured by NMR. The minima in the relaxation time at the fields for level crossing are due to the quantum tunneling of the magnetization. The shortening of the relaxation time under the application of H T is shown to be due mainly to the reduction of the energy barrier

Investigation of dielectric relaxation in systems with hierarchical organization: From time to frequency domain and back again

Energy Technology Data Exchange (ETDEWEB)

Yokoi, Koki [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI (United States); Raicu, Valerică, E-mail: vraicu@uwm.edu [Department of Physics, University of Wisconsin-Milwaukee, Milwaukee, WI (United States); Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, WI (United States)

2017-06-28

Relaxation in fractal structures was investigated theoretically starting from a simple model of a Cantorian tree and kinetic equations linking the change in the number of particles (e.g., electrical charges) populating each branch of the tree and their transfer to other branches or to the ground state. We numerically solved the system of differential equations obtained and determined the so-called cumulative distribution function of particles, which, in dielectric or mechanical relaxation parlance, is the same as the relaxation function of the system. As a physical application, we studied the relationship between the dielectric relaxation in time-domain and the dielectric dispersion in the frequency-domain. Upon choosing appropriate rate constants, our model described accurately well-known non-exponential and non-Debye time- and frequency-domain functions, such as stretched exponentials, Havrilliak–Negami, and frequency power law. Our approach opens the door to applying kinetic models to describe a wide array of relaxation processes, which traditionally have posed great challenges to theoretical modeling based on first principles. - Highlights: • Relaxation was investigated for a system of particles flowing through a Cantorian tree. • A set of kinetic equations was formulated and used to compute the relaxation function of the system. • The dispersion function of the system was computed from the relaxation function. • An analytical method was used to recover the original relaxation function from the dispersion function. • This formalism was used to study dielectric relaxation and dispersion in fractal structures.

Advanced Deployable Structural Systems for Small Satellites

Science.gov (United States)

Belvin, W. Keith; Straubel, Marco; Wilkie, W. Keats; Zander, Martin E.; Fernandez, Juan M.; Hillebrandt, Martin F.

2016-01-01

One of the key challenges for small satellites is packaging and reliable deployment of structural booms and arrays used for power, communication, and scientific instruments. The lack of reliable and efficient boom and membrane deployment concepts for small satellites is addressed in this work through a collaborative project between NASA and DLR. The paper provides a state of the art overview on existing spacecraft deployable appendages, the special requirements for small satellites, and initial concepts for deployable booms and arrays needed for various small satellite applications. The goal is to enhance deployable boom predictability and ground testability, develop designs that are tolerant of manufacturing imperfections, and incorporate simple and reliable deployment systems.

Uniform Distance Scaling Behavior of Planet-Satellite Nanostructures Made by Star Polymers.

Science.gov (United States)

Rossner, Christian; Tang, Qiyun; Glatter, Otto; Müller, Marcus; Vana, Philipp

2017-02-28

Planet-satellite nanostructures from RAFT star polymers and larger (planet) as well as smaller (satellite) gold nanoparticles are analyzed in experiments and computer simulations regarding the influence of arm number of star polymers. A uniform scaling behavior of planet-satellite distances as a function of arm length was found both in the dried state (via transmission electron microscopy) after casting the nanostructures on surfaces and in the colloidally dispersed state (via simulations and small-angle X-ray scattering) when 2-, 3-, and 6-arm star polymers were employed. This indicates that the planet-satellite distances are mainly determined by the arm length of star polymers. The observed discrepancy between TEM and simulated distances can be attributed to the difference of polymer configurations in dried and dispersed state. Our results also show that these distances are controlled by the density of star polymers end groups, and the number of grabbed satellite particles is determined by the magnitude of the corresponding density. These findings demonstrate the feasibility to precisely control the planet-satellite structures at the nanoscale.

Treatment of Test Anxiety by Cue-Controlled Relaxation and Systematic Desensitization

Science.gov (United States)

Russell, Richard K.; And Others

1976-01-01

Test-anxious subjects (N=19) participated in an outcome study comparing systematic desensitization, cue-controlled relaxation, and no treatment. The treatment groups demonstrated significant improvement on the self-report measures of test and state anxiety but not on the behavioral indices. The potential advantages of this technique over…

Ultrafast relaxation dynamics of electrons in Au clusters capped with dodecanethiol molecules

International Nuclear Information System (INIS)

Hamanaka, Y.; Fukagawa, K.; Tai, Y.; Murakami, J.; Nakamura, A.

2006-01-01

We have investigated electron relaxation dynamics of size-selected Au clusters capped by dodecanethiol molecules in the cluster sizes of 28-142 atoms using femtosecond pump-probe spectroscopy. Absorption spectra of 28-71-atom clusters show discrete peaks due to the optical transitions between quantized states, while an absorption band due to the surface plasmon is observed in 142-atom clusters. In the differential absorption spectra measured by the pump-probe experiments, a large redshift of 140 meV lasting over 10 ps and absorption bleaching decaying within 2 ps are observed at the absorption peaks of 28-atom clusters. The redshift is ascribed to a charge transfer between Au clusters and dodecanethiol molecules adsorbed on the cluster surface, and the bleaching is due to blocking of the optical transitions between the ground state and the occupied electronic states due to the Pauli's-exclusion principle. Such behavior is in contrast to the 142-atom clusters, where the cooling of hot electrons generated by photo-excitation determines the relaxation dynamics. These results indicate molecular properties of the 28-atom Au cluster-dodecanethiol system

[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

Dielectric relaxation studies in super-cooled liquid and glassy phases of anti-cancerous alkaloid: Brucine

Science.gov (United States)

Afzal, Aboothahir; Shahin Thayyil, M.; Sulaiman, M. K.; Kulkarni, A. R.

2018-05-01

Brucine has good anti-tumor effects, on both liver cancer and breast cancer. It has bioavailability of 40.83%. Since the bioavailability of the drug is low, an alternative method to increase its bioavailability and solubility is by changing the drug into glassy form. We used Differential Scanning Calorimetry (DSC) for studying the glass forming ability of the drug. Brucine was found to be a very good glass former glass transition temperature 365 K. Based on the DSC analysis we have used broadband dielectric spectroscopy (BDS) for studying the drug in the super cooled and glassy state. BDS is an effective tool to probe the molecular dynamics in the super cooled and glassy state. Molecular mobility is found to be present even in the glassy state of this active pharmaceutical ingredient (API) which is responsible for the instability. Our aim is to study the factors responsible for instability of this API in amorphous form. Cooling curves for dielectric permittivity and dielectric loss revealed the presence of structural (α) and secondary relaxations (β and γ). Temperature dependence of relaxation time is fitted by Vogel-Fulcher-Tammann equation and found the values of activation energy of the α relaxation, fragility and glass transition temperature. Paluch's anti correlation is also verified, that the width of the α-loss peak at or near the glass transition temperature Tg is strongly anticorrelated with the polarity of the molecule. The larger the dielectric relaxation strength Δɛ (Tg) of the system, the narrower is the α-loss peak (higher value of βKWW).

Hierarchical relaxation dynamics in a tilted two-band Bose-Hubbard model

Science.gov (United States)

Cosme, Jayson G.

2018-04-01

We numerically examine slow and hierarchical relaxation dynamics of interacting bosons described by a tilted two-band Bose-Hubbard model. The system is found to exhibit signatures of quantum chaos within the spectrum and the validity of the eigenstate thermalization hypothesis for relevant physical observables is demonstrated for certain parameter regimes. Using the truncated Wigner representation in the semiclassical limit of the system, dynamics of relevant observables reveal hierarchical relaxation and the appearance of prethermalized states is studied from the perspective of statistics of the underlying mean-field trajectories. The observed prethermalization scenario can be attributed to different stages of glassy dynamics in the mode-time configuration space due to dynamical phase transition between ergodic and nonergodic trajectories.

Electronic relaxation dynamics of a metal atom deposited on argon cluster

International Nuclear Information System (INIS)

Awali, Slim

2014-01-01

This thesis is a study on the interaction between electronically excited atomic states and a non-reactive environment. We have theoretically and experimentally studied situations where a metal atom (Ba or K) is placed in a finite size environment (argon cluster). The presence of the medium affects the electronic levels of the atom. On the other side, the excitation of the atom induces a relaxation dynamics of the electronic energy through the deformation of the cluster. The experimental part of this work focuses on two aspects: the spectroscopy and the dynamics. In both cases a first laser electronically excites the metal atom and the second ionizes the excited system. The observable is the photoelectron spectrum recorded after photoionization and possibly information on the photoion which are also produced. This pump/probe technique, with also two lasers, provide the ultrafast dynamic when the lasers pulses used are of ultrashort (60 fs). The use of nanosecond lasers leads to resonance spectroscopic measurement, unresolved temporally, which give information on the position of the energy levels of the studied system. From a theoretical point-of-view, the excited states of M-Ar n were calculated at the ab initio level, using large core pseudo-potential to limit the active electrons of the metal to valence electrons. The study of alkali metals (potassium) is especially well adapted to this method since only one electron is active. The ab-initio calculation and a Monte-Carlo simulation where coupled to optimize the geometry of the KAr n (n = 1-10) cluster when K is in the ground state of the neutral and the ion, or excited in the 4p or 5s state. Calculations were also conducted in collaboration with B. Gervais (CIMAP, Caen) on KAr n clusters having several tens of argon atoms. Absorption spectra were also calculated. From an experimental point-of-view, we were able to characterize the excited states of potassium and barium perturbed by the clusters. In both cases a

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 ...

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3{NIT(C6H4OPh)}]: A μ+ spin relaxation study

Science.gov (United States)

Arosio, Paolo; Corti, Maurizio; Mariani, Manuel; Orsini, Francesco; Bogani, Lapo; Caneschi, Andrea; Lago, Jorge; Lascialfari, Alessandro

2015-05-01

The spin dynamics of the molecular magnetic chain [Dy(hfac)3{NIT(C6H4OPh)}] were investigated by means of the Muon Spin Relaxation (μ+SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac)3{NIT(C6H4OPh)}] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing μ+SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, two stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate λinterm(T), associated with the intermediate relaxing component. The experimental λinterm(T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to τ = τ0 exp(Δ/kBT), corresponding to a distribution of energy barriers Δ. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state.

Local spin dynamics at low temperature in the slowly relaxing molecular chain [Dy(hfac)3(NIT(C6H4OPh))]: A μ+ spin relaxation study

International Nuclear Information System (INIS)

Arosio, Paolo; Orsini, Francesco; Corti, Maurizio; Mariani, Manuel; Bogani, Lapo; Caneschi, Andrea; Lago, Jorge; Lascialfari, Alessandro

2015-01-01

The spin dynamics of the molecular magnetic chain [Dy(hfac) 3 (NIT(C 6 H 4 OPh))] were investigated by means of the Muon Spin Relaxation (μ + SR) technique. This system consists of a magnetic lattice of alternating Dy(III) ions and radical spins, and exhibits single-chain-magnet behavior. The magnetic properties of [Dy(hfac) 3 (NIT(C 6 H 4 OPh))] have been studied by measuring the magnetization vs. temperature at different applied magnetic fields (H = 5, 3500, and 16500 Oe) and by performing μ + SR experiments vs. temperature in zero field and in a longitudinal applied magnetic field H = 3500 Oe. The muon asymmetry P(t) was fitted by the sum of three components, two stretched-exponential decays with fast and intermediate relaxation times, and a third slow exponential decay. The temperature dependence of the spin dynamics has been determined by analyzing the muon longitudinal relaxation rate λ interm (T), associated with the intermediate relaxing component. The experimental λ interm (T) data were fitted with a corrected phenomenological Bloembergen-Purcell-Pound law by using a distribution of thermally activated correlation times, which average to τ = τ 0 exp(Δ/k B T), corresponding to a distribution of energy barriers Δ. The correlation times can be associated with the spin freezing that occurs when the system condenses in the ground state

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

Mechanisms of relaxation and spin decoherence in nanomagnets

Science.gov (United States)

van Tol, Johan

Relaxation in spin systems is of great interest with respect to various possible applications like quantum information processing and storage, spintronics, and dynamic nuclear polarization (DNP). The implementation of high frequencies and fields is crucial in the study of systems with large zero-field splitting or large interactions, as for example molecular magnets and low dimensional magnetic materials. Here we will focus on the implementation of pulsed Electron Paramagnetic Resonance (ERP) at multiple frequencies of 10, 95, 120, 240, and 336 GHz, and the relaxation and decoherence processes as a function of magnetic field and temperature. Firstly, at higher frequencies the direct single-phonon spin-lattice relaxation (SLR) is considerably enhanced, and will more often than not be the dominant relaxation mechanism at low temperatures, and can be much faster than at lower fields and frequencies. In principle the measurement of the SLR rates as a function of the frequency provides a means to map the phonon density of states. Secondly, the high electron spin polarization at high fields has a strong influence on the spin fluctuations in relatively concentrated spin systems, and the contribution of the electron-electron dipolar interactions to the coherence rate can be partially quenched at low temperatures. This not only allows the study of relatively concentrated spin systems by pulsed EPR (as for example magnetic nanoparticles and molecular magnets), it enables the separation of the contribution of the fluctuations of the electron spin system from other decoherence mechanisms. Besides choice of temperature and field, several strategies in sample design, pulse sequences, or clock transitions can be employed to extend the coherence time in nanomagnets. A review will be given of the decoherence mechanisms with an attempt at a quantitative comparison of experimental rates with theory.

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)

Creep and stress relaxation behavior of two soft denture liners.

Science.gov (United States)

Salloum, Alaa'a M

2014-03-01

Numerous investigators stated the indications of soft denture lining materials; but no one determined the indications of these materials according to their chemical structure. The purpose of this investigation was to evaluate the viscoelastic properties of acrylic and silicon lining materials. This study investigated and compared viscoelastic properties of two resilient denture lining materials. Tested materials were laboratory processed; one of them was silicone-based liner product (Molloplast-B), and the other was plasticized acrylic resin (Vertex™ Soft). Twenty cylindrical specimens (10-20 mm in length, 11.55 mm in diameter) were fabricated in an aluminum mold from each material for creep and stress relaxation testing (the study of viscoelastic properties). Tests were performed by using the universal testing machine DY-34. Collected data were analyzed with t test statistics for statistically significant differences at the 95 % confidence level. There was a clear difference in creep and stress relaxation behavior between acrylic and silicone liners. Statistical study of Young's moduli illustrated that Vertex™ Soft was softer than Molloplast-B. On the other hand, the results explained that the recovery of silicone material was better than of acrylic one. The creep test revealed that the plasticized acrylic resin lining material exhibited considerable creep, whereas silicone-based liner exhibited elastic behavior. Besides, the stress relaxation test showed that relaxation of the plasticized acrylic resin material was bigger than of the silicone-based liner.

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.

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

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 # ...

The Relaxation of Vicinal (001) with ZigZag [110] Steps

Science.gov (United States)

Hawkins, Micah; Hamouda, Ajmi Bh; González-Cabrera, Diego Luis; Einstein, Theodore L.

2012-02-01

This talk presents a kinetic Monte Carlo study of the relaxation dynamics of [110] steps on a vicinal (001) simple cubic surface. This system is interesting because [110] steps have different elementary excitation energetics and favor step diffusion more than close-packed [100] steps. In this talk we show how this leads to relaxation dynamics showing greater fluctuations on a shorter time scale for [110] steps as well as 2-bond breaking processes being rate determining in contrast to 3-bond breaking processes for [100] steps. The existence of a steady state is shown via the convergence of terrace width distributions at times much longer than the relaxation time. In this time regime excellent fits to the modified generalized Wigner distribution (as well as to the Berry-Robnik model when steps can overlap) were obtained. Also, step-position correlation function data show diffusion-limited increase for small distances along the step as well as greater average step displacement for zigzag steps compared to straight steps for somewhat longer distances along the step. Work supported by NSF-MRSEC Grant DMR 05-20471 as well as a DOE-CMCSN Grant.

Nonequilibrium thermodynamics and information theory: basic concepts and relaxing dynamics

Science.gov (United States)

Altaner, Bernhard

2017-11-01

Thermodynamics is based on the notions of energy and entropy. While energy is the elementary quantity governing physical dynamics, entropy is the fundamental concept in information theory. In this work, starting from first principles, we give a detailed didactic account on the relations between energy and entropy and thus physics and information theory. We show that thermodynamic process inequalities, like the second law, are equivalent to the requirement that an effective description for physical dynamics is strongly relaxing. From the perspective of information theory, strongly relaxing dynamics govern the irreversible convergence of a statistical ensemble towards the maximally non-commital probability distribution that is compatible with thermodynamic equilibrium parameters. In particular, Markov processes that converge to a thermodynamic equilibrium state are strongly relaxing. Our framework generalizes previous results to arbitrary open and driven systems, yielding novel thermodynamic bounds for idealized and real processes. , which features invited work from the best early-career researchers working within the scope of J. Phys. A. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Bernhard Altaner was selected by the Editorial Board of J. Phys. A as an Emerging Talent.

Creep and inverse stress relaxation behaviors of carbon nanotube yarns.

Science.gov (United States)

Misak, H E; Sabelkin, V; Miller, L; Asmatulu, R; Mall, S

2013-12-01

Creep, creep recovery and inverse stress relaxation behaviors of carbon nanotube yarns that consisted of 1-, 30-, and 100-yarn(s) were characterized. Primary and secondary creep stages were observed over the duration of 336 h. The primary creep stage lasted for about 4 h at an applied load equal to 75% of the ultimate tensile strength. The total strain in the primary stage was significantly larger in the carbon nanotube multi-yarn than in the carbon nanotube 1-yarn. In the secondary stage, 1-yarn also had a smaller steady state strain rate than the multi-yarn, and it was independent of number of yarns in multi-yarn. Strain response under cyclic creep loading condition was comparable to its counterpart in non-cyclic (i.e., standard) creep test except that strain response during the first cycle was slightly different from the subsequent cycles. Inverse creep (i.e., strain recovery) was observed in the 100-yarn during the cyclic creep tests after the first unloading cycle. Furthermore, inverse stress relaxation of the multi-yarns was characterized. Inverse stress relaxation was larger and for longer duration with the larger number of yarns.

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...

Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA

Science.gov (United States)

Mroue, Kamal H.; Zhang, Rongchun; Zhu, Peizhi; McNerny, Erin; Kohn, David H.; Morris, Michael D.; Ramamoorthy, Ayyalusamy

2014-07-01

Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA = Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI). In this study, we demonstrate that Gd-DTPA can also be effectively used to enhance the longitudinal relaxation rates of protons in solid-state NMR experiments conducted on bone without significant line-broadening and chemical-shift-perturbation side effects. Using bovine cortical bone samples incubated in different concentrations of Gd-DTPA complex, the 1H T1 values were calculated from data collected by 1H spin-inversion recovery method detected in natural-abundance 13C cross-polarization magic angle spinning (CPMAS) NMR experiments. Our results reveal that the 1H T1 values can be successfully reduced by a factor of 3.5 using as low as 10 mM Gd-DTPA without reducing the spectral resolution and thus enabling faster data acquisition of the 13C CPMAS spectra. These results obtained from 13C-detected CPMAS experiments were further confirmed using 1H-detected ultrafast MAS experiments on Gd-DTPA doped bone samples. This approach considerably improves the signal-to-noise ratio per unit time of NMR experiments applied to bone samples by reducing the experimental time required to acquire the same number of scans.

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.)

Soviet satellite communications science and technology

Energy Technology Data Exchange (ETDEWEB)

Birch, J.N.; Campanella, S.J.; Gordon, G.D.; McElroy, D.R.; Pritchard, W.L.; Stamminger, R.

1991-08-01

This is a report by six US scientists and engineers concerning the current state of the art and projections of future Soviet satellite communications technologies. The panel members are experts in satellite stabilization, spacecraft environments, space power generation, launch systems, spacecraft communications sciences and technologies, onboard processing, ground stations, and other technologies that impact communications. The panel assessed the Soviet ability to support high-data-rate space missions at 128 Mbps by evaluating current and projected Soviet satellite communications technologies. A variety of space missions were considered, including Earth-to-Earth communications via satellites in geostationary or highly elliptical orbits, those missions that require space-to-Earth communications via a direct path and those missions that require space-to-Earth communications via a relay satellite. Soviet satellite communications capability, in most cases, is 10 years behind that of the United States and other industrialized nations. However, based upon an analysis of communications links needed to support these missions using current Soviet capabilities, it is well within the current Soviet technology to support certain space missions outlined above at rates of 128 Mbps or higher, although published literature clearly shows that the Soviet Union has not exceeded 60 Mbps in its current space system. These analyses are necessary but not sufficient to determine mission data rates, and other technologies such as onboard processing and storage could limit the mission data rate well below that which could actually be supported via the communications links. Presently, the Soviet Union appears to be content with data rates in the low-Earth-orbit relay via geostationary mode of 12 Mbps. This limit is a direct result of power amplifier limits, spacecraft antenna size, and the utilization of K{sub u}-band frequencies. 91 refs., 16 figs., 15 tabs.

Ferromagnetism versus slow paramagnetic relaxation in Fe-doped Li3N

Science.gov (United States)

Fix, M.; Jesche, A.; Jantz, S. G.; Bräuninger, S. A.; Klauss, H.-H.; Manna, R. S.; Pietsch, I. M.; Höppe, H. A.; Canfield, P. C.

2018-02-01

We report on isothermal magnetization, Mössbauer spectroscopy, and magnetostriction as well as temperature-dependent alternating-current (ac) susceptibility, specific heat, and thermal expansion of single crystalline and polycrystalline Li2(Li1 -xFex) N with x =0 and x ≈0.30 . Magnetic hysteresis emerges at temperatures below T ≈50 K with coercivity fields of up to μ0H =11.6 T at T =2 K and magnetic anisotropy energies of 310 K (27 meV). The ac susceptibility is strongly frequency-dependent (f =10 -10 000 Hz) and reveals an effective energy barrier for spin reversal of Δ E ≈1100 K (90 meV). The relaxation times follow Arrhenius behavior for T >25 K . For T <10 K , however, the relaxation times of τ ≈1010 s are only weakly temperature-dependent, indicating the relevance of a quantum tunneling process instead of thermal excitations. The magnetic entropy amounts to more than 25 J molFe-1 K-1, which significantly exceeds R ln 2 , the value expected for the entropy of a ground-state doublet. Thermal expansion and magnetostriction indicate a weak magnetoelastic coupling in accordance with slow relaxation of the magnetization. The classification of Li2(Li1 -xFex) N as ferromagnet is stressed and contrasted with highly anisotropic and slowly relaxing paramagnetic behavior.

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Directory of Open Access Journals (Sweden)

Ghangho Kim

2015-04-01

Full Text Available A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO satellite using single-epoch measurements from a Global Positioning System (GPS receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS. Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state.

Coarse Initial Orbit Determination for a Geostationary Satellite Using Single-Epoch GPS Measurements

Science.gov (United States)

Kim, Ghangho; Kim, Chongwon; Kee, Changdon

2015-01-01

A practical algorithm is proposed for determining the orbit of a geostationary orbit (GEO) satellite using single-epoch measurements from a Global Positioning System (GPS) receiver under the sparse visibility of the GPS satellites. The algorithm uses three components of a state vector to determine the satellite’s state, even when it is impossible to apply the classical single-point solutions (SPS). Through consideration of the characteristics of the GEO orbital elements and GPS measurements, the components of the state vector are reduced to three. However, the algorithm remains sufficiently accurate for a GEO satellite. The developed algorithm was tested on simulated measurements from two or three GPS satellites, and the calculated maximum position error was found to be less than approximately 40 km or even several kilometers within the geometric range, even when the classical SPS solution was unattainable. In addition, extended Kalman filter (EKF) tests of a GEO satellite with the estimated initial state were performed to validate the algorithm. In the EKF, a reliable dynamic model was adapted to reduce the probability of divergence that can be caused by large errors in the initial state. PMID:25835299

Multidimensional dynamic piezoresponse measurements. Unraveling local relaxation behavior in relaxor-ferroelectrics via big data

International Nuclear Information System (INIS)

Vasudevan, Rama K.; Zhang, Shujun; Okatan, Mahmut Baris; Jesse, Stephen; Kalinin, Sergei V.; Bassiri-Gharb, Nazanin

2015-01-01

Compositional and charge disorder in ferroelectric relaxors lies at the heart of the unusual properties of these systems, such as aging and non-ergodicity, polarization rotations, and a host of temperature and field-driven phase transitions. However, much information about the field-dynamics of the polarization in the prototypical ferroelectric relaxor (1-x)Pb(Mg 1/3 Nb 2/3 )O 3-x PbTiO 3 (PMN-xPT) remains unprobed at the mesoscopic level. We use a piezoresponse force microscopy-based dynamic multimodal relaxation spectroscopy technique, enabling the study of ferroelectric switching and polarization relaxation at mesoscopic length scales, and carry out measurements on a PMN-0.28PT sample with minimal polishing. Results indicate that beyond a threshold DC bias the average relaxation increases as the system attempts to relax to the previous state. Phenomenological fitting reveals the presence of mesoscale heterogeneity in relaxation amplitudes and clearly suggests the presence of two distinct amplitudes. Independent component analysis reveals the presence of a disorder component of the relaxation, which is found to be strongly anti-correlated with the maximum piezoresponse at that location, suggesting smaller disorder effects where the polarization reversal is large and vice versa. The disorder in the relaxation amplitudes is postulated to arise from rhombohedral and field-induced tetragonal phase in the crystal, with each phase associated with its own relaxation amplitude. As a result, these studies highlight the crucial importance of the mixture of ferroelectric phases in the compositions in proximity of the morphotropic phase boundary in governing the local response and further highlight the ability of PFM voltage and time spectroscopies, in conjunction with big-data multivariate analyses, to locally map disorder and correlate it with parameters governing the dynamic behavior

Structural assurance testing for post-shipping satellite inspection

Science.gov (United States)

Reynolds, Whitney D.; Doyle, Derek; Arritt, Brandon

2012-04-01

Current satellite transportation sensors can provide a binary indication of the acceleration or shock that a satellite has experienced during the shipping process but do little to identify if significant structural change has occurred in the satellite and where it may be located. When a sensor indicates that the satellite has experienced shock during transit, an extensive testing process begins to evaluate the satellite functionality. If errors occur during the functional checkout, extensive physical inspection of the structure follows. In this work an alternate method for inspecting satellites for structural defects after shipping is presented. Electro- Mechanical Impedance measurements are used as an indication of the structural state. In partnership with the Air Force Research Laboratory University Nanosatellite Program, Cornell's CUSat mass model was instrumented with piezoelectric transducers and tested under several structural damage scenarios. A method for detecting and locating changes in the structure using EMI data is presented.

Diffusion relaxation times of nonequilibrium isolated small bodies and their solid phase ensembles to equilibrium states

Science.gov (United States)

Tovbin, Yu. K.

2017-08-01

The possibility of obtaining analytical estimates in a diffusion approximation of the times needed by nonequilibrium small bodies to relax to their equilibrium states based on knowledge of the mass transfer coefficient is considered. This coefficient is expressed as the product of the self-diffusion coefficient and the thermodynamic factor. A set of equations for the diffusion transport of mixture components is formulated, characteristic scales of the size of microheterogeneous phases are identified, and effective mass transfer coefficients are constructed for them. Allowing for the developed interface of coexisting and immiscible phases along with the porosity of solid phases is discussed. This approach can be applied to the diffusion equalization of concentrations of solid mixture components in many physicochemical systems: the mutual diffusion of components in multicomponent systems (alloys, semiconductors, solid mixtures of inert gases) and the mass transfer of an absorbed mobile component in the voids of a matrix consisting of slow components or a mixed composition of mobile and slow components (e.g., hydrogen in metals, oxygen in oxides, and the transfer of molecules through membranes of different natures, including polymeric).

Image velocimetry for clouds with relaxation labeling based on deformation consistency

International Nuclear Information System (INIS)

Horinouchi, Takeshi; Murakami, Shin-ya; Yamazaki, Atsushi; Kouyama, Toru; Ogohara, Kazunori; Yamada, Manabu; Watanabe, Shigeto

2017-01-01

Correlation-based cloud tracking has been extensively used to measure atmospheric winds, but still difficulty remains. In this study, aiming at developing a cloud tracking system for Akatsuki, an artificial satellite orbiting Venus, a formulation is developed for improving the relaxation labeling technique to select appropriate peaks of cross-correlation surfaces which tend to have multiple peaks. The formulation makes an explicit use of consistency inherent in the type of cross-correlation method where template sub-images are slid without deformation; if the resultant motion vectors indicate a too-large deformation, it is contradictory to the assumption of the method. The deformation consistency is exploited further to develop two post processes; one clusters the motion vectors into groups within each of which the consistency is perfect, and the other extends the groups using the original candidate lists. These processes are useful to eliminate erroneous vectors, distinguish motion vectors at different altitudes, and detect phase velocities of waves in fluids such as atmospheric gravity waves. As a basis of the relaxation labeling and the post processes as well as uncertainty estimation, the necessity to find isolated (well-separated) peaks of cross-correlation surfaces is argued, and an algorithm to realize it is presented. All the methods are implemented, and their effectiveness is demonstrated with initial images obtained by the ultraviolet imager onboard Akatsuki. Since the deformation consistency regards the logical consistency inherent in template matching methods, it should have broad application beyond cloud tracking. (paper)

Image velocimetry for clouds with relaxation labeling based on deformation consistency

Science.gov (United States)

Horinouchi, Takeshi; Murakami, Shin-ya; Kouyama, Toru; Ogohara, Kazunori; Yamazaki, Atsushi; Yamada, Manabu; Watanabe, Shigeto

2017-08-01

Correlation-based cloud tracking has been extensively used to measure atmospheric winds, but still difficulty remains. In this study, aiming at developing a cloud tracking system for Akatsuki, an artificial satellite orbiting Venus, a formulation is developed for improving the relaxation labeling technique to select appropriate peaks of cross-correlation surfaces which tend to have multiple peaks. The formulation makes an explicit use of consistency inherent in the type of cross-correlation method where template sub-images are slid without deformation; if the resultant motion vectors indicate a too-large deformation, it is contradictory to the assumption of the method. The deformation consistency is exploited further to develop two post processes; one clusters the motion vectors into groups within each of which the consistency is perfect, and the other extends the groups using the original candidate lists. These processes are useful to eliminate erroneous vectors, distinguish motion vectors at different altitudes, and detect phase velocities of waves in fluids such as atmospheric gravity waves. As a basis of the relaxation labeling and the post processes as well as uncertainty estimation, the necessity to find isolated (well-separated) peaks of cross-correlation surfaces is argued, and an algorithm to realize it is presented. All the methods are implemented, and their effectiveness is demonstrated with initial images obtained by the ultraviolet imager onboard Akatsuki. Since the deformation consistency regards the logical consistency inherent in template matching methods, it should have broad application beyond cloud tracking.

Dynamics of exciton relaxation in LH2 antenna probed by multipulse nonlinear spectroscopy.

Science.gov (United States)

Novoderezhkin, Vladimir I; Cohen Stuart, Thomas A; van Grondelle, Rienk

2011-04-28

We explain the relaxation dynamics in the LH2-B850 antenna as revealed by multipulse pump-dump-probe spectroscopy (Th. A. Cohen Stuart, M. Vengris, V. I. Novoderezhkin, R. J. Cogdell, C. N. Hunter, R. van Grondelle, submitted). The theory of pump-dump-probe response is evaluated using the doorway-window approach in combination with the modified Redfield theory. We demonstrate that a simultaneous fit of linear spectra, pump-probe, and pump-dump-probe kinetics can be obtained at a quantitative level using the disordered exciton model, which is essentially the same as used to model the spectral fluctuations in single LH2 complexes (Novoderezhkin, V.; Rutkauskas, D.; van Grondelle, R. Biophys. J. 2006, 90, 2890). The present studies suggest that the observed relaxation rates are strongly dependent on the realization of the disorder. A big spread of the rates (exceeding 3 orders of magnitude) is correlated with the disorder-induced changes in delocalization length and overlap of the exciton wave functions. We conclude that the bulk kinetics reflect a superposition of many pathways corresponding to different physical limits of energy transfer, varying from sub-20 fs relaxation between delocalized and highly spatially overlapping exciton states to >20 ps jumps between states localized at the opposite sides of the ring.

Experimental evidence for simultaneous relaxation processes in super spin glass γ-Fe{sub 2}O{sub 3} nanoparticle system

Energy Technology Data Exchange (ETDEWEB)

Nikolic, V.; Perovic, M., E-mail: mara.perovic@vinca.rs; Kusigerski, V.; Boskovic, M.; Mrakovic, A.; Blanusa, J.; Spasojevic, V. [University of Belgrade, Condensed Matter Physics Laboratory, Institute of Nuclear Sciences Vinca (Serbia)

2015-03-15

Spherical γ-Fe{sub 2}O{sub 3} nanoparticles with the narrow size distribution of (5 ± 1) nm were synthesized by the method of thermal decomposition from iron acetyl acetonate precursor. The existence of super spin-glass state at low temperatures and in low applied magnetic fields was confirmed by DC magnetization measurements on a SQUID magnetometer. The comprehensive investigation of magnetic relaxation dynamics in low-temperature region was conducted through the measurements of single-stop and multiple stop ZFC memory effects, ZFC magnetization relaxation, and AC susceptibility measurements. The experimental findings revealed the peculiar change of magnetic relaxation dynamics at T ≈ 10 K, which arose as a consequence of simultaneous existence of different relaxation processes in Fe{sub 2}O{sub 3} nanoparticle system. Complementarity of the applied measurements was utilized in order to single out distinct relaxation processes as well as to elucidate complex relaxation mechanisms in the investigated interacting nanoparticle system.

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)

Theoretical and experimental study of the relaxation of excited states of the DCM laser dye. Intra-molecular electron transfer and photo-isomerization. Solvent effects

International Nuclear Information System (INIS)

Marguet, Sylvie

1992-01-01

This research thesis reports the study of a styrenic laser dye, the 4-(dicyanomethylene)-2-methyl-6-[p-(dimethylamino) styryl]-4H-pyrane or DCM for the characterization of the first electronic states and of the influence of the solvent on efficiencies of different relaxation processes of the first excited state S1 of the DCM. Due to the presence of a combination of a donor group and acceptor group, this compound has interesting properties of intra-molecular charge transfer and of photo-isomerization which highly depend on solvent polarity. Two approaches have been adopted to study these complementary processes: an experimental approach (determination of rate constants of the different deactivation ways of the S1 state by measuring fluorescence quantum efficiencies, photo-isomerization quantum efficiencies, and fluorescence lifetimes of DCM in about twenty solvent of increasing polarity), and a computational approach (a CS-INDO-MRI type quantum chemistry calculation to obtain potential energy curves, charge distributions, and dipolar moments of DCM first electronic states) [fr

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)

Relaxation of photoconductivity and persistent photoconductivity in TiO2 nanotubes

International Nuclear Information System (INIS)

Enachi, Mihail; Braniste, Tudor; Borodin, Eugeniu; Postolache, Vitalie

2013-01-01

Relaxation of photoconductivity is investigated in titania nanotubes produced by electrochemical treatment of Ti foils in organic electrolytes with subsequent thermal treatment at 400 degrees Celsius in air. The photoconductivity was excited both in air and in vacuum with the radiation from a xenon lamp passed through different filters to vary the excitation intensity and wavelength. It was found that the photoconductivity relaxation process consists of two components, i. e. a fast component a slow one. These two components behave differently in air and in the vacuum. The fast component is even faster under vacuum, while the slow component in vacuum is much slower, therefore leading to persistent photoconductivity. The possibility of removing the persistent photoconductivity state by exposure to air is investigated. (authors)

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.

Consensus of satellite cluster flight using an energy-matching optimal control method

Science.gov (United States)

Luo, Jianjun; Zhou, Liang; Zhang, Bo

2017-11-01

This paper presents an optimal control method for consensus of satellite cluster flight under a kind of energy matching condition. Firstly, the relation between energy matching and satellite periodically bounded relative motion is analyzed, and the satellite energy matching principle is applied to configure the initial conditions. Then, period-delayed errors are adopted as state variables to establish the period-delayed errors dynamics models of a single satellite and the cluster. Next a novel satellite cluster feedback control protocol with coupling gain is designed, so that the satellite cluster periodically bounded relative motion consensus problem (period-delayed errors state consensus problem) is transformed to the stability of a set of matrices with the same low dimension. Based on the consensus region theory in the research of multi-agent system consensus issues, the coupling gain can be obtained to satisfy the requirement of consensus region and decouple the satellite cluster information topology and the feedback control gain matrix, which can be determined by Linear quadratic regulator (LQR) optimal method. This method can realize the consensus of satellite cluster period-delayed errors, leading to the consistency of semi-major axes (SMA) and the energy-matching of satellite cluster. Then satellites can emerge the global coordinative cluster behavior. Finally the feasibility and effectiveness of the present energy-matching optimal consensus for satellite cluster flight is verified through numerical simulations.

Transverse magnetic field effects on the relaxation time of the magnetization in Mn12 measured by {sup 55}Mn-NMR

Energy Technology Data Exchange (ETDEWEB)

Furukawa, Y.; Watanabe, K.; Kumagai, K.; Borsa, F.; Gatteschi, D

2003-05-01

The longitudinal (H{sub Z}) and transverse (H{sub T}) magnetic field dependence of the relaxation time of the magnetization in Mn12 in its S=10 ground state was measured by NMR. The minima in the relaxation time at the fields for level crossing are due to the quantum tunneling of the magnetization. The shortening of the relaxation time under the application of H{sub T} is shown to be due mainly to the reduction of the energy barrier.

Synchronization of pairwise-coupled, identical, relaxation oscillators based on metal-insulator phase transition devices: A model study

Science.gov (United States)

Parihar, Abhinav; Shukla, Nikhil; Datta, Suman; Raychowdhury, Arijit

2015-02-01

Computing with networks of synchronous oscillators has attracted wide-spread attention as novel materials and device topologies have enabled realization of compact, scalable and low-power coupled oscillatory systems. Of particular interest are compact and low-power relaxation oscillators that have been recently demonstrated using MIT (metal-insulator-transition) devices using properties of correlated oxides. Further the computational capability of pairwise coupled relaxation oscillators has also been shown to outperform traditional Boolean digital logic circuits. This paper presents an analysis of the dynamics and synchronization of a system of two such identical coupled relaxation oscillators implemented with MIT devices. We focus on two implementations of the oscillator: (a) a D-D configuration where complementary MIT devices (D) are connected in series to provide oscillations and (b) a D-R configuration where it is composed of a resistor (R) in series with a voltage-triggered state changing MIT device (D). The MIT device acts like a hysteresis resistor with different resistances in the two different states. The synchronization dynamics of such a system has been analyzed with purely charge based coupling using a resistive (RC) and a capacitive (CC) element in parallel. It is shown that in a D-D configuration symmetric, identical and capacitively coupled relaxation oscillator system synchronizes to an anti-phase locking state, whereas when coupled resistively the system locks in phase. Further, we demonstrate that for certain range of values of RC and CC, a bistable system is possible which can have potential applications in associative computing. In D-R configuration, we demonstrate the existence of rich dynamics including non-monotonic flows and complex phase relationship governed by the ratios of the coupling impedance. Finally, the developed theoretical formulations have been shown to explain experimentally measured waveforms of such pairwise coupled

Viscous relaxation as a prerequisite for tectonic resurfacing on Ganymede: Insights from numerical models of lithospheric extension

Science.gov (United States)

Bland, Michael T.; McKinnon, William B.

2018-05-01

Ganymede's bright terrain formed during a near-global resurfacing event (or events) that produced both heavily tectonized and relatively smooth terrains. The mechanism(s) by which resurfacing occurred on Ganymede (e.g., cryovolcanic or tectonic), and the relationship between the older, dark and the younger, bright terrain are fundamental to understanding the geological evolution of the satellite. Using a two-dimensional numerical model of lithospheric extension that has previously been used to successfully simulate surface deformation consistent with grooved terrain morphologies, we investigate whether large-amplitude preexisting topography can be resurfaced (erased) by extension (i.e., tectonic resurfacing). Using synthetically produced initial topography, we show that when the total relief of the initial topography is larger than 25-50 m, periodic groove-like structures fail to form. Instead, extension is localized in a few individual, isolated troughs. These results pose a challenge to the tectonic resurfacing hypothesis. We further investigate the effects of preexisting topography by performing suites of simulations initialized with topography derived from digital terrain models of Ganymede's surface. These include dark terrain, fresh (relatively deep) impact craters, smooth bright terrain, and a viscously relaxed impact crater. The simulations using dark terrain and fresh impact craters are consistent with our simulations using synthetic topography: periodic groove-like deformation fails to form. In contrast, when simulations were initialized with bright smooth terrain topography, groove-like deformation results from a wide variety of heat flow and surface temperature conditions. Similarly, when a viscously relaxed impact crater was used, groove-like structures were able to form during extension. These results suggest that tectonic resurfacing may require that the amplitude of the initial topography be reduced before extension begins. We emphasize that viscous

Non-equilibrium relaxation in a stochastic lattice Lotka-Volterra model

Science.gov (United States)

Chen, Sheng; Täuber, Uwe C.

2016-04-01

We employ Monte Carlo simulations to study a stochastic Lotka-Volterra model on a two-dimensional square lattice with periodic boundary conditions. If the (local) prey carrying capacity is finite, there exists an extinction threshold for the predator population that separates a stable active two-species coexistence phase from an inactive state wherein only prey survive. Holding all other rates fixed, we investigate the non-equilibrium relaxation of the predator density in the vicinity of the critical predation rate. As expected, we observe critical slowing-down, i.e., a power law dependence of the relaxation time on the predation rate, and algebraic decay of the predator density at the extinction critical point. The numerically determined critical exponents are in accord with the established values of the directed percolation universality class. Following a sudden predation rate change to its critical value, one finds critical aging for the predator density autocorrelation function that is also governed by universal scaling exponents. This aging scaling signature of the active-to-absorbing state phase transition emerges at significantly earlier times than the stationary critical power laws, and could thus serve as an advanced indicator of the (predator) population’s proximity to its extinction threshold.

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

Body mass index, metabolic factors, and striatal activation during stressful and neutral-relaxing states: an FMRI study.

Science.gov (United States)

Jastreboff, Ania M; Potenza, Marc N; Lacadie, Cheryl; Hong, Kwangik A; Sherwin, Robert S; Sinha, Rajita

2011-02-01

Stress is associated with alterations in neural motivational-reward pathways in the ventral striatum (VS), hormonal/metabolic changes, and weight increases. The relationship between these different factors is not well understood. We hypothesized that body mass index (BMI) status and hormonal/metabolic factors would be associated with VS activation. We used functional magnetic resonance imaging (fMRI) to compare brain responses of overweight and obese (OW/OB: BMI ≥ 25 kg/m(2): N=27) individuals with normal weight (NW: BMI<18.5-24.9 kg/m(2): N=21) individuals during exposure to personalized stress, alcohol cue, and neutral-relaxing situations using a validated, autobiographical, script-driven, guided-imagery paradigm. Metabolic factors, including fasting plasma glucose (FPG), insulin, and leptin, were examined for their association with VS activation. Consistent with previous studies, stress and alcohol cue exposure each increased activity in cortico-limbic regions. Compared with NW individuals, OW/OB individuals showed greater VS activation in the neutral-relaxing and stress conditions. FPG was correlated with VS activation. Significant associations between VS activation and metabolic factors during stress and relaxation suggest the involvement of metabolic factors in striatal dysfunction in OW/OB individuals. This relationship may contribute to non-homeostatic feeding in obesity.

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

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

Phase synchronization in a two-mode solid state laser: Periodic modulations with the second relaxation oscillation frequency of the laser output

International Nuclear Information System (INIS)

Hsu, Tzu-Fang; Jao, Kuan-Hsuan; Hung, Yao-Chen

2014-01-01

Phase synchronization (PS) in a periodically pump-modulated two-mode solid state laser is investigated. Although PS in the laser system has been demonstrated in response to a periodic modulation with the main relaxation oscillation (RO) frequency of the free-running laser, little is known about the case of modulation with minor RO frequencies. In this Letter, the empirical mode decomposition (EMD) method is utilized to decompose the laser time series into a set of orthogonal modes and to examine the intrinsic PS near the frequency of the second RO. The degree of PS is quantified by means of a histogram of phase differences and the analysis of Shannon entropy. - Highlights: • We study the intrinsic phase synchronization in a periodically pump-modulated two-mode solid state laser. • The empirical mode decomposition method is utilized to define the intrinsic phase synchronization. • The degree of phase synchronization is quantified by a proposed synchronization coefficient

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

Defense Meteorological Satellite Program (DMSP) Film

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The United States Air Force Defense Meteorological Satellite Program (DMSP) Operational Linescan System (OLS) is a polar orbiting meteorological sensor with two...

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.

Understanding charge carrier relaxation processes in terbium arsenide nanoparticles using transient absorption spectroscopy

Science.gov (United States)

Vanderhoef, Laura R.

Erbium arsenide nanoparticles epitaxially grown within III-V semiconductors have been shown to improve the performance of devices for applications ranging from thermoelectrics to THz pulse generation. The small size of rare-earth nanoparticles suggests that interesting electronic properties might emerge as a result of both spatial confinement and surface states. However, ErAs nanoparticles do not exhibit any signs of quantum confinement or an emergent bandgap, and these experimental observations are understood from theory. The incorporation of other rare-earth monopnictide nanoparticles into III-V hosts is a likely path to engineering carrier excitation, relaxation and transport dynamics for optoelectronic device applications. However, the electronic structure of these other rare-earth monopnictide nanoparticles remains poorly understood. The objective of this research is to explore the electronic structure and optical properties of III-V materials containing novel rare-earth monopnictides. We use ultrafast pump-probe spectroscopy to investigate the electronic structure of TbAs nanoparticles in III-V hosts. We start with TbAs:GaAs, which was expected to be similar to ErAs:GaAs. We study the dynamics of carrier relaxation into the TbAs states using optical pump terahertz probe transient absorption spectroscopy. By analyzing how the carrier relaxation rates depend on pump fluence and sample temperature, we conclude that the TbAs states are saturable. Saturable traps suggest the existence of a bandgap for TbAs nanoparticles, in sharp contrast with previous results for ErAs. We then apply the same experimental technique to two samples of TbAs nanoparticles in InGaAs with different concentrations of TbAs. We observe similar relaxation dynamics associated with trap saturation, though the ability to resolve these processes is contingent upon a high enough TbAs concentration in the sample. We have also constructed an optical pump optical probe transient absorption

Magnetic relaxation behaviour in Pr{sub 2}NiSi{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Pakhira, Santanu, E-mail: santanupakhira20006@gmail.com; Mazumdar, Chandan; Ranganathan, R. [Condensed Matter Physics Division, Saha Institute Of Nuclear Physics, 1/AF Bidhannagar, Kolkata-700064 (India)

2016-05-06

Time dependent isothemal remanent magnetizatin (IRM) behaviour for polycrystalline compound Pr{sub 2}NiSi{sub 3} have been studied below its characteristic temperature. The compound undergoes slow magnetic relaxation with time. Along with competing interaction, non-magnetic atom disorder plays an important role in formation of non-equilibrium glassy like ground state for this compound.

Relaxation dynamics of a driven two-level system coupled to a Bose-Einstein condensate: application to quantum dot-dipolar exciton gas hybrid systems.

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Kovalev, Vadim M; Tse, Wang-Kong

2017-11-22

We develop a microscopic theory for the relaxation dynamics of an optically pumped two-level system (TLS) coupled to a bath of weakly interacting Bose gas. Using Keldysh formalism and diagrammatic perturbation theory, expressions for the relaxation times of the TLS Rabi oscillations are derived when the boson bath is in the normal state and the Bose-Einstein condensate (BEC) state. We apply our general theory to consider an irradiated quantum dot coupled with a boson bath consisting of a two-dimensional dipolar exciton gas. When the bath is in the BEC regime, relaxation of the Rabi oscillations is due to both condensate and non-condensate fractions of the bath bosons for weak TLS-light coupling and pre dominantly due to the non-condensate fraction for strong TLS-light coupling. Our theory also shows that a phase transition of the bath from the normal to the BEC state strongly influences the relaxation rate of the TLS Rabi oscillations. The TLS relaxation rate is approximately independent of the pump field frequency and monotonically dependent on the field strength when the bath is in the low-temperature regime of the normal phase. Phase transition of the dipolar exciton gas leads to a non-monotonic dependence of the TLS relaxation rate on both the pump field frequency and field strength, providing a characteristic signature for the detection of BEC phase transition of the coupled dipolar exciton gas.

Randomized controlled trial of relaxation music to reduce heart rate in patients undergoing cardiac CT.

Science.gov (United States)

Ng, Ming Yen; Karimzad, Yasser; Menezes, Ravi J; Wintersperger, Bernd J; Li, Qin; Forero, Julian; Paul, Narinder S; Nguyen, Elsie T

2016-10-01

To evaluate the heart rate lowering effect of relaxation music in patients undergoing coronary CT angiography (CCTA), pulmonary vein CT (PVCT) and coronary calcium score CT (CCS). Patients were randomised to a control group (i.e. standard of care protocol) or to a relaxation music group (ie. standard of care protocol with music). The groups were compared for heart rate, radiation dose, image quality and dose of IV metoprolol. Both groups completed State-Trait Anxiety Inventory anxiety questionnaires to assess patient experience. One hundred and ninety-seven patients were recruited (61.9 % males); mean age 56y (19-86 y); 127 CCTA, 17 PVCT, 53 CCS. No significant difference in heart rate, radiation dose, image quality, metoprolol dose and anxiety scores. 86 % of patients enjoyed the music. 90 % of patients in the music group expressed a strong preference to have music for future examinations. The patient cohort demonstrated low anxiety levels prior to CT. Relaxation music in CCTA, PVCT and CCS does not reduce heart rate or IV metoprolol use. Patients showed low levels of anxiety indicating that anxiolytics may not have a significant role in lowering heart rate. Music can be used in cardiac CT to improve patient experience. • Relaxation music does not reduce heart rate in cardiac CT • Relaxation music does not reduce beta-blocker use in cardiac CT • Relaxation music has no effect on cardiac CT image quality • Low levels of anxiety are present in patients prior to cardiac CT • Patients enjoyed the relaxation music and this results in improved patient experience.

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

Recapitulation of Extracellular LAMININ Environment Maintains Stemness of Satellite Cells In Vitro.

Science.gov (United States)

Ishii, Kana; Sakurai, Hidetoshi; Suzuki, Nobuharu; Mabuchi, Yo; Sekiya, Ichiro; Sekiguchi, Kiyotoshi; Akazawa, Chihiro

2018-02-13

Satellite cells function as precursor cells in mature skeletal muscle homeostasis and regeneration. In healthy tissue, these cells are maintained in a state of quiescence by a microenvironment formed by myofibers and basement membrane in which LAMININs (LMs) form a major component. In the present study, we evaluated the satellite cell microenvironment in vivo and found that these cells are encapsulated by LMα2-5. We sought to recapitulate this satellite cell niche in vitro by culturing satellite cells in the presence of recombinant LM-E8 fragments. We show that treatment with LM-E8 promotes proliferation of satellite cells in an undifferentiated state, through reduced phosphorylation of JNK and p38. On transplantation into injured muscle tissue, satellite cells cultured with LM-E8 promoted the regeneration of skeletal muscle. These findings represent an efficient method of culturing satellite cells for use in transplantation through the recapitulation of the satellite cell niche using recombinant LM-E8 fragments. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

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…

Quantum process tomography with informational incomplete data of two J-coupled heterogeneous spins relaxation in a time window much greater than T1

Science.gov (United States)

Maciel, Thiago O.; Vianna, Reinaldo O.; Sarthour, Roberto S.; Oliveira, Ivan S.

2015-11-01

We reconstruct the time dependent quantum map corresponding to the relaxation process of a two-spin system in liquid-state NMR at room temperature. By means of quantum tomography techniques that handle informational incomplete data, we show how to properly post-process and normalize the measurements data for the simulation of quantum information processing, overcoming the unknown number of molecules prepared in a non-equilibrium magnetization state (Nj) by an initial sequence of radiofrequency pulses. From the reconstructed quantum map, we infer both longitudinal (T1) and transversal (T2) relaxation times, and introduce the J-coupling relaxation times ({T}1J,{T}2J), which are relevant for quantum information processing simulations. We show that the map associated to the relaxation process cannot be assumed approximated unital and trace-preserving for times greater than {T}2J.

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....

Satellite structure in Auger and (e,2e) spectra of germanium

International Nuclear Information System (INIS)

Went, M.R.; Vos, M.; Kheifets, A.S.

2006-01-01

The interpretation of electron spectroscopy data is often complicated by the presence of satellites. These satellites are either due to different final states reached after the excitation (intrinsic satellites) or due to energy loss experienced by the escaping electron on its way out the target (extrinsic satellites). Unravelling these two contributions in an unambiguous way is difficult. In this paper we compare the intrinsic satellite structures obtained for germanium by two different high-energy spectroscopies: Auger spectroscopy of deep core levels and valence band electron momentum spectroscopy. Despite the different nature of the two probes we find a similar shape of the intrinsic satellites and comparable intensity

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

Integrating a relaxation response-based curriculum into a public high school in Massachusetts.

Science.gov (United States)

Foret, Megan M; Scult, Matthew; Wilcher, Marilyn; Chudnofsky, Rana; Malloy, Laura; Hasheminejad, Nicole; Park, Elyse R

2012-04-01

Academic and societal pressures result in U.S. high school students feeling stressed. Stress management and relaxation interventions may help students increase resiliency to stress and overall well-being. The objectives of this study were to examine the feasibility (enrollment, participation and acceptability) and potential effectiveness (changes in perceived stress, anxiety, self-esteem, health-promoting behaviors, and locus of control) of a relaxation response (RR)-based curriculum integrated into the school day for high school students. The curriculum included didactic instruction, relaxation exercises, positive psychology, and cognitive restructuring. The intervention group showed significantly greater improvements in levels of perceived stress, state anxiety, and health-promoting behaviors when compared to the wait list control group. The intervention appeared most useful for girls in the intervention group. The results suggest that several modifications may increase the feasibility of using this potentially effective intervention in high schools. Copyright © 2011 The Foundation for Professionals in Services for Adolescents. Published by Elsevier Ltd. All rights reserved.