Pullback attractors for three-dimensional non-autonomous Navier–Stokes–Voigt equations
International Nuclear Information System (INIS)
García-Luengo, Julia; Marín-Rubio, Pedro; Real, José
2012-01-01
In this paper, we consider a non-autonomous Navier–Stokes–Voigt model, with which a continuous process can be associated. We study the existence and relationship between minimal pullback attractors for this process in two different frameworks, namely, for the universe of fixed bounded sets, and also for another universe given by a tempered condition. Since the model does not have a regularizing effect, obtaining asymptotic compactness for the process is a more involved task. We prove this in a relatively simple way just using an energy method. Our results simplify—and in some aspects generalize—some of those obtained previously for the autonomous and non-autonomous cases, since for example in section 4, regularity is not required for the boundary of the domain and the force may take values in V'. Under additional suitable assumptions, regularity results for these families of attractors are also obtained, via bootstrapping arguments. Finally, we also conclude some results concerning the attraction in the D(A) norm
Discerning non-autonomous dynamics
Energy Technology Data Exchange (ETDEWEB)
Clemson, Philip T.; Stefanovska, Aneta, E-mail: aneta@lancaster.ac.uk
2014-09-30
Structure and function go hand in hand. However, while a complex structure can be relatively safely broken down into the minutest parts, and technology is now delving into nanoscales, the function of complex systems requires a completely different approach. Here the complexity clearly arises from nonlinear interactions, which prevents us from obtaining a realistic description of a system by dissecting it into its structural component parts. At best, the result of such investigations does not substantially add to our understanding or at worst it can even be misleading. Not surprisingly, the dynamics of complex systems, facilitated by increasing computational efficiency, is now readily tackled in the case of measured time series. Moreover, time series can now be collected in practically every branch of science and in any structural scale—from protein dynamics in a living cell to data collected in astrophysics or even via social networks. In searching for deterministic patterns in such data we are limited by the fact that no complex system in the real world is autonomous. Hence, as an alternative to the stochastic approach that is predominantly applied to data from inherently non-autonomous complex systems, theory and methods specifically tailored to non-autonomous systems are needed. Indeed, in the last decade we have faced a huge advance in mathematical methods, including the introduction of pullback attractors, as well as time series methods that cope with the most important characteristic of non-autonomous systems—their time-dependent behaviour. Here we review current methods for the analysis of non-autonomous dynamics including those for extracting properties of interactions and the direction of couplings. We illustrate each method by applying it to three sets of systems typical for chaotic, stochastic and non-autonomous behaviour. For the chaotic class we select the Lorenz system, for the stochastic the noise-forced Duffing system and for the non-autonomous
Discerning non-autonomous dynamics
International Nuclear Information System (INIS)
Clemson, Philip T.; Stefanovska, Aneta
2014-01-01
Structure and function go hand in hand. However, while a complex structure can be relatively safely broken down into the minutest parts, and technology is now delving into nanoscales, the function of complex systems requires a completely different approach. Here the complexity clearly arises from nonlinear interactions, which prevents us from obtaining a realistic description of a system by dissecting it into its structural component parts. At best, the result of such investigations does not substantially add to our understanding or at worst it can even be misleading. Not surprisingly, the dynamics of complex systems, facilitated by increasing computational efficiency, is now readily tackled in the case of measured time series. Moreover, time series can now be collected in practically every branch of science and in any structural scale—from protein dynamics in a living cell to data collected in astrophysics or even via social networks. In searching for deterministic patterns in such data we are limited by the fact that no complex system in the real world is autonomous. Hence, as an alternative to the stochastic approach that is predominantly applied to data from inherently non-autonomous complex systems, theory and methods specifically tailored to non-autonomous systems are needed. Indeed, in the last decade we have faced a huge advance in mathematical methods, including the introduction of pullback attractors, as well as time series methods that cope with the most important characteristic of non-autonomous systems—their time-dependent behaviour. Here we review current methods for the analysis of non-autonomous dynamics including those for extracting properties of interactions and the direction of couplings. We illustrate each method by applying it to three sets of systems typical for chaotic, stochastic and non-autonomous behaviour. For the chaotic class we select the Lorenz system, for the stochastic the noise-forced Duffing system and for the non-autonomous
Deconvolution of Moessbauer spectra using Voigt functions
International Nuclear Information System (INIS)
Flores Ll, H.J.
1990-08-01
The form of the resonance line in Moessbauer spectroscopy is a form of Lorentzian line, but this form of line it enlarges due to several effects: finite thickness of the absorber, instrumental instability, diffusion of Co 57 in crystals and fluctuations in the environment of the emitting nucleus. To take into account this effects it has been used as form of line in Moessbauer spectroscopy the Voigt function that is the convolution of a Lorentzian and a Gaussian. (Author)
Some results on the well-posedness of Euler-Voigt and Navier-Stokes-Voigt models
Berselli, Luigi C.; Bisconti, Luca
2010-01-01
We consider the Euler-Voigt equations and the Navier-Stokes-Voigt equations, which are obtained by an inviscid alpha-regularization from the corresponding equations. The main result we show is the structural stability of the system in term of the variations of both viscosity of regularization parameters.
Energy Technology Data Exchange (ETDEWEB)
Flores Ll, H J
1990-08-15
The form of the resonance line in Moessbauer spectroscopy is a form of Lorentzian line, but this form of line it enlarges due to several effects: finite thickness of the absorber, instrumental instability, diffusion of Co{sup 57} in crystals and fluctuations in the environment of the emitting nucleus. To take into account this effects it has been used as form of line in Moessbauer spectroscopy the Voigt function that is the convolution of a Lorentzian and a Gaussian. (Author)
approximate controllability of a non-autonomous differential equation
Indian Academy of Sciences (India)
53
for a non-autonomous functional differential equation using the theory of linear ... approximate controllability of various functional differential equations in abstract ...... the operator A(t) and into the requirement that x(t) ∈ D(A) for all t ≥ 0.
International Nuclear Information System (INIS)
Jimenez-Dominguez, H.; Flores-Llamas, H.; Cabral-Prieto, C.; Bravo-Ortega, A.
1989-01-01
A relationship is presented between the Lorentzian-Gaussian profile convolutions and the plasma dispersion function; thus, the methods available to calculate the latter serve also to calculate the Voigt profile. (orig.)
International Nuclear Information System (INIS)
Jimenez D, H.; Flores L, H.; Cabral P, A.; Bravo O, A.
1990-05-01
A relationship among the Lorentzian-Gaussian profile convolution and the Plasma Dispersion Function is presented; thus, the methods available to calculate the latter serve also to calculate the Voigt profile. (Author)
Diagonalizing quadratic bosonic operators by non-autonomous flow equations
Bach, Volker
2016-01-01
The authors study a non-autonomous, non-linear evolution equation on the space of operators on a complex Hilbert space. They specify assumptions that ensure the global existence of its solutions and allow them to derive its asymptotics at temporal infinity. They demonstrate that these assumptions are optimal in a suitable sense and more general than those used before. The evolution equation derives from the Brocketâe"Wegner flow that was proposed to diagonalize matrices and operators by a strongly continuous unitary flow. In fact, the solution of the non-linear flow equation leads to a diagonalization of Hamiltonian operators in boson quantum field theory which are quadratic in the field.
Functional envelope of a non-autonomous discrete system
Directory of Open Access Journals (Sweden)
Barzanouni Ali
2017-11-01
Full Text Available Let (X, F = {fn}n =0∞ be a non-autonomous discrete system by a compact metric space X and continuous maps fn : X → X, n = 0, 1, ....We introduce functional envelope (S(X, G = {Gn}n =0∞, of (X, F = {fn}n =0∞, where S(X is the space of all continuous self maps of X and the map Gn : S(X → S(X is defined by Gn(ϕ = Fn ∘ ϕ, Fn = fn ∘ fn-1 ∘ . . . ∘ f1 ∘ f0. The paper mainly deals with the connection between the properties of a system and the properties of its functional envelope.
A stochastic perturbation theory for non-autonomous systems
Energy Technology Data Exchange (ETDEWEB)
Moon, W., E-mail: wm275@damtp.cam.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Wettlaufer, J. S., E-mail: wettlaufer@maths.ox.ac.uk [Yale University, New Haven, Connecticut 06520-8109 (United States); Mathematical Institute, University of Oxford, Oxford OX2 6GG (United Kingdom)
2013-12-15
We develop a perturbation theory for a class of first order nonlinear non-autonomous stochastic ordinary differential equations that arise in climate physics. The perturbative procedure produces moments in terms of integral delay equations, whose order by order decay is characterized in a Floquet-like sense. Both additive and multiplicative sources of noise are discussed and the question of how the nature of the noise influences the results is addressed theoretically and numerically. By invoking the Martingale property, we rationalize the transformation of the underlying Stratonovich form of the model to an Ito form, independent of whether the noise is additive or multiplicative. The generality of the analysis is demonstrated by developing it both for a Brownian particle moving in a periodically forced quartic potential, which acts as a simple model of stochastic resonance, as well as for our more complex climate physics model. The validity of the approach is shown by comparison with numerical solutions. The particular climate dynamics problem upon which we focus involves a low-order model for the evolution of Arctic sea ice under the influence of increasing greenhouse gas forcing ΔF{sub 0}. The deterministic model, developed by Eisenman and Wettlaufer [“Nonlinear threshold behavior during the loss of Arctic sea ice,” Proc. Natl. Acad. Sci. U.S.A. 106(1), 28–32 (2009)] exhibits several transitions as ΔF{sub 0} increases and the stochastic analysis is used to understand the manner in which noise influences these transitions and the stability of the system.
Symmetries and solutions of the non-autonomous von Bertalanffy equation
Edwards, Maureen P.; Anderssen, Robert S.
2015-05-01
For growth in a closed environment, which is indicative of the situation in laboratory experiments, autonomous ODE models do not necessarily capture the dynamics under investigation. The importance and impact of a closed environment arise when the question under examination relates, for example, to the number of the surviving microbes, such as in a study of the spoilage and contamination of food, the gene silencing activity of fungi or the production of a chemical compound by bacteria or fungi. Autonomous ODE models are inappropriate as they assume that only the current size of the population controls the growth-decay dynamics. This is reflected in the fact that, asymptotically, their solutions can only grow or decay monotonically or asymptote. Non-autonomous ODE models are not so constrained. A natural strategy for the choice of non-autonomous ODEs is to take appropriate autonomous ones and change them to be non-autonomous through the introduction of relevant non-autonomous terms. This is the approach in this paper with the focus being the von Bertalanffy equation. Since this equation has independent importance in relation to practical applications in growth modelling, it is natural to explore the deeper relationships between the introduced non-autonomous terms through a symmetry analysis, which is the purpose and goal of the current paper. Infinitesimals are derived which allow particular forms of the non-autonomous von Bertalanffy equation to be transformed into autonomous forms for which some new analytic solutions have been found.
International Nuclear Information System (INIS)
Palma, Daniel A.P.; Goncalves, Alessandro da C; Martinez, Aquilino S.
2011-01-01
The Voigt function H(a,v) is defined as the convolution of the Gaussian and Lorentzian functions. Recent papers puplished in different areas of physics emphasize the importance of the fast and accurate calculation of the Voigt function for different orders of magnitude of variables a and v. An alternative analytical formulation for the Voigt function is proposed in this paper. This formulation is based on the solution of the non-homogeneous ordinary differential equation, satisfied by the Voigt function, using the Frobenius and parameter variation methods. The functional form of the Voigt function, as proposed, proved simple and precise. Systematic tests are accomplished demonstrating some advantages with other existent methods in the literature and with the numeric method of reference.
Energy Technology Data Exchange (ETDEWEB)
Palma, Daniel A.P., E-mail: dpalmaster@gmail.com [CNEN-Comissao Nacional de Energia Nuclear, 22290-901, Rio de Janeiro (Brazil); Goncalves, Alessandro da C; Martinez, Aquilino S. [COPPE/UFRJ-Programa de Engenharia Nuclear, 21941-972, Rio de Janeiro (Brazil)
2011-10-21
The Voigt function H(a,v) is defined as the convolution of the Gaussian and Lorentzian functions. Recent papers puplished in different areas of physics emphasize the importance of the fast and accurate calculation of the Voigt function for different orders of magnitude of variables a and v. An alternative analytical formulation for the Voigt function is proposed in this paper. This formulation is based on the solution of the non-homogeneous ordinary differential equation, satisfied by the Voigt function, using the Frobenius and parameter variation methods. The functional form of the Voigt function, as proposed, proved simple and precise. Systematic tests are accomplished demonstrating some advantages with other existent methods in the literature and with the numeric method of reference.
Global asymptotical ω-periodicity of a fractional-order non-autonomous neural networks.
Chen, Boshan; Chen, Jiejie
2015-08-01
We study the global asymptotic ω-periodicity for a fractional-order non-autonomous neural networks. Firstly, based on the Caputo fractional-order derivative it is shown that ω-periodic or autonomous fractional-order neural networks cannot generate exactly ω-periodic signals. Next, by using the contraction mapping principle we discuss the existence and uniqueness of S-asymptotically ω-periodic solution for a class of fractional-order non-autonomous neural networks. Then by using a fractional-order differential and integral inequality technique, we study global Mittag-Leffler stability and global asymptotical periodicity of the fractional-order non-autonomous neural networks, which shows that all paths of the networks, starting from arbitrary points and responding to persistent, nonconstant ω-periodic external inputs, asymptotically converge to the same nonconstant ω-periodic function that may be not a solution. Copyright © 2015 Elsevier Ltd. All rights reserved.
Directory of Open Access Journals (Sweden)
Bixiang Wang
2013-08-01
Full Text Available We prove the existence and uniqueness of random attractors for the p-Laplace equation driven simultaneously by non-autonomous deterministic and stochastic forcing. The nonlinearity of the equation is allowed to have a polynomial growth rate of any order which may be greater than p. We further establish the upper semicontinuity of random attractors as the intensity of noise approaches zero. In addition, we show the pathwise periodicity of random attractors when all non-autonomous deterministic forcing terms are time periodic.
International Nuclear Information System (INIS)
Limandri, Silvina P.; Bonetto, Rita D.; Di Rocco, Hector O.; Trincavelli, Jorge C.
2008-01-01
The Voigt function is the convolution between a Gaussian and a Lorentzian distribution. The numerical implementation of this function is required in diverse areas of physics and applied mathematics. An explicit representation for the Voigt function is developed in terms of series of trigonometric and hyperbolic functions. The obtained expression permits a very fast evaluation of Voigt profiles with a degree of accuracy higher than the one required for spectroscopy applications. In addition, this expression is implemented in a numerical algorithm of parameter optimization in electron probe microanalysis, and applied to determine natural linewidths for several transitions to the uranium M levels
Energy Technology Data Exchange (ETDEWEB)
Limandri, Silvina P. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina); Bonetto, Rita D. [Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina) and Centro de Investigacion y Desarrollo en Ciencias Aplicadas Dr. Jorge Ronco, Calle 47 No 257, 1900 La Plata, Argentina; Facultad de Ciencias Exactas y Facultad de Ingenieria de la UNLP, La Plata (Argentina); Di Rocco, Hector O. [Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina); Instituto de Fisica Arroyo Seco, Facultad de Ciencias Exactas, Universidad Nacional del Centro, Pinto 399, 7000 Tandil (Argentina); Trincavelli, Jorge C. [Facultad de Matematica, Astronomia y Fisica, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000, Cordoba (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas de la Republica Argentina (Argentina)], E-mail: jorge@quechua.fis.uncor.edu
2008-09-15
The Voigt function is the convolution between a Gaussian and a Lorentzian distribution. The numerical implementation of this function is required in diverse areas of physics and applied mathematics. An explicit representation for the Voigt function is developed in terms of series of trigonometric and hyperbolic functions. The obtained expression permits a very fast evaluation of Voigt profiles with a degree of accuracy higher than the one required for spectroscopy applications. In addition, this expression is implemented in a numerical algorithm of parameter optimization in electron probe microanalysis, and applied to determine natural linewidths for several transitions to the uranium M levels.
Asymptotic behaviour of unbounded trajectories for some non-autonomous systems in a Hilbert space
International Nuclear Information System (INIS)
Djafari Rouhani, B.
1990-07-01
The asymptotic behaviour of unbounded trajectories for non expansive mappings in a real Hilbert space and the extension to more general Banach spaces and to nonlinear contraction semi-group have been studied by many authors. In this paper we study the asymptotic behaviour of unbounded trajectories for a quasi non-autonomous dissipative systems. 26 refs
Energy Technology Data Exchange (ETDEWEB)
Flores Ll, H.; Cabral P, A.; Jimenez D, H
1990-01-15
The fundamental parameters of the Voigt function are determined: lorentzian wide ({gamma}{sub L}) and gaussian wide ({gamma}{sub G}) with an error for almost all the cases inferior to 1% in the intervals 0.01 {<=} {gamma}{sub L} / {gamma}{sub G} {<=}1 and 0.3 {<=} {gamma}{sub G} / {gamma}{sub L} {<=}1. This is achieved using the least square fit method with an algebraic function, being obtained a simple method to obtain the fundamental parameters of the Voigt function used in many spectroscopies. (Author)
Local Properties of Solutions to Non-Autonomous Parabolic PDEs with State-Dependent Delays
Czech Academy of Sciences Publication Activity Database
Rezunenko, Oleksandr
2012-01-01
Roč. 2, č. 2 (2012), s. 56-71 ISSN 2158-611X R&D Projects: GA ČR(CZ) GAP103/12/2431 Institutional support: RVO:67985556 Keywords : partial differential equations * state-dependent delay * invariance principle Subject RIV: BC - Control Systems Theory http://library.utia.cas.cz/separaty/2012/AS/rezunenko- local properties of solutions to non-autonomous parabolic PDEs with state-dependent delay s.pdf
Obtention of the parameters of the Voigt function using the least square fit method
International Nuclear Information System (INIS)
Flores Ll, H.; Cabral P, A.; Jimenez D, H.
1990-01-01
The fundamental parameters of the Voigt function are determined: lorentzian wide (Γ L ) and gaussian wide (Γ G ) with an error for almost all the cases inferior to 1% in the intervals 0.01 ≤ Γ L / Γ G ≤1 and 0.3 ≤ Γ G / Γ L ≤1. This is achieved using the least square fit method with an algebraic function, being obtained a simple method to obtain the fundamental parameters of the Voigt function used in many spectroscopies. (Author)
Fibonacci-based hardware post-processing for non-autonomous signum hyperchaotic system
Mansingka, Abhinav S.; Barakat, Mohamed L.; Zidan, Mohammed A.; Radwan, Ahmed Gomaa; Salama, Khaled N.
2013-01-01
This paper presents a hardware implementation of a robust non-autonomous hyperchaotic-based PRNG driven by a 256-bit LFSR. The original chaotic output is post-processed using a novel technique based on the Fibonacci series, bitwise XOR, rotation, and feedback. The proposed post-processing technique preserves the throughput of the system and enhances the randomness in the output which is verified by successfully passing all NIST SP. 800-22 tests. The system is realized on a Xilinx Virtex 4 FPGA achieving throughput up to 13.165 Gbits/s for 16-bit bus-width surpassing previously reported CB-PRNGs. © 2013 IEEE.
Internal crisis in a second-order non-linear non-autonomous electronic oscillator
International Nuclear Information System (INIS)
Stavrinides, S.G.; Deliolanis, N.C.; Miliou, A.N.; Laopoulos, Th.; Anagnostopoulos, A.N.
2008-01-01
The internal crisis of a second-order non-linear non-autonomous chaotic electronic circuit is studied. The phase portraits consist of two interacting sub-attractors, a chaotic and a periodic one. Maximal Lyapunov exponents were calculated, for both the periodic and the chaotic waveforms, in order to confirm their nature. Transitions between the chaotic and the periodic sub-attractors become more frequent by increasing the circuit driving frequency. The frequency distribution of the corresponding laminar lengths and their average values indicate that an internal crisis takes place in this circuit, manifested in the intermittent behaviour of the corresponding orbits
Fibonacci-based hardware post-processing for non-autonomous signum hyperchaotic system
Mansingka, Abhinav S.
2013-12-01
This paper presents a hardware implementation of a robust non-autonomous hyperchaotic-based PRNG driven by a 256-bit LFSR. The original chaotic output is post-processed using a novel technique based on the Fibonacci series, bitwise XOR, rotation, and feedback. The proposed post-processing technique preserves the throughput of the system and enhances the randomness in the output which is verified by successfully passing all NIST SP. 800-22 tests. The system is realized on a Xilinx Virtex 4 FPGA achieving throughput up to 13.165 Gbits/s for 16-bit bus-width surpassing previously reported CB-PRNGs. © 2013 IEEE.
On the Moral Acceptability of Physician-Assisted Dying for Non-Autonomous Psychiatric Patients.
Varelius, Jukka
2016-05-01
Several authors have recently suggested that the suffering caused by mental illness could provide moral grounds for physician-assisted dying. Yet they typically require that psychiatric-assisted dying could come to question in the cases of autonomous, or rational, psychiatric patients only. Given that also non-autonomous psychiatric patients can sometimes suffer unbearably, this limitation appears questionable. In this article, I maintain that restricting psychiatric-assisted dying to autonomous, or rational, psychiatric patients would not be compatible with endorsing certain end-of-life practices commonly accepted in current medical ethics and law, practices often referred to as 'passive euthanasia'. © 2015 John Wiley & Sons Ltd.
Observation of the X-ray magneto-optical voigt effect
Czech Academy of Sciences Publication Activity Database
Mertins, H. Ch.; Oppeneer, P. M.; Kuneš, Jan; Gaupp, A.; Abramsohn, D.; Schäfers, F.
2001-01-01
Roč. 87, č. 4 (2001), s. 047401-1-047401-4 ISSN 0031-9007 Grant - others:-(DE) ERB FMG ECT /980105 Institutional research plan: CEZ:A02/98:Z1-010-914 Keywords : x-ray magneto-optical Voigt effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 6.668, year: 2001
Mida suudab muusikateraapia? / Melanie Voigt, Esa Ala-Ruona ; inetrvjueerinud Kristel Kossar
Voigt, Melanie
2012-01-01
Eesti Muusika- ja Teatriakadeemias toimunud Euroopa Muusikateraapia Konföderatsiooni peaassambleel ja sümpoosionil ettekannetega esinenud muusikaterapeudid Malanie Voigt Saksamaalt ja Esa Ala-Ruona Soomest räägivad tööst puuetega lastega ja tööstressist ning heliilmast
TRX-1 Regulates SKN-1 Nuclear Localization Cell Non-autonomously in Caenorhabditis elegans.
McCallum, Katie C; Liu, Bin; Fierro-González, Juan Carlos; Swoboda, Peter; Arur, Swathi; Miranda-Vizuete, Antonio; Garsin, Danielle A
2016-05-01
The Caenorhabditis elegans oxidative stress response transcription factor, SKN-1, is essential for the maintenance of redox homeostasis and is a functional ortholog of the Nrf family of transcription factors. The numerous levels of regulation that govern these transcription factors underscore their importance. Here, we add a thioredoxin, encoded by trx-1, to the expansive list of SKN-1 regulators. We report that loss of trx-1 promotes nuclear localization of intestinal SKN-1 in a redox-independent, cell non-autonomous fashion from the ASJ neurons. Furthermore, this regulation is not general to the thioredoxin family, as two other C. elegans thioredoxins, TRX-2 and TRX-3, do not play a role in this process. Moreover, TRX-1-dependent regulation requires signaling from the p38 MAPK-signaling pathway. However, while TRX-1 regulates SKN-1 nuclear localization, classical SKN-1 transcriptional activity associated with stress response remains largely unaffected. Interestingly, RNA-Seq analysis revealed that loss of trx-1 elicits a general, organism-wide down-regulation of several classes of genes; those encoding for collagens and lipid transport being most prevalent. Together, these results uncover a novel role for a thioredoxin in regulating intestinal SKN-1 nuclear localization in a cell non-autonomous manner, thereby contributing to the understanding of the processes involved in maintaining redox homeostasis throughout an organism. Copyright © 2016 by the Genetics Society of America.
Non-autonomous Regulation of Neuronal Migration by Insulin Signaling, DAF-16/FOXO and PAK-1
Kennedy, Lisa M.; Pham, Steven C.D.L.; Grishok, Alla
2013-01-01
SUMMARY Neuronal migration is essential for nervous system development in all organisms and is regulated in the nematode, C. elegans, by signaling pathways that are conserved in humans. Here, we demonstrate that the Insulin/IGF-1-PI3K signaling pathway modulates the activity of the DAF-16/FOXO transcription factor to promote the anterior migrations of the hermaphrodite-specific neurons (HSNs) during embryogenesis of C. elegans. When signaling is reduced, DAF-16 is activated and promotes migration, conversely, when signaling is enhanced, DAF-16 is inactivated and migration is inhibited. We show that DAF-16 acts non-autonomously in the hypodermis to promote HSN migration. Furthermore, we identify PAK-1, a p21-activated kinase, as a downstream mediator of Insulin/IGF-1-DAF-16 signaling in the non-autonomous control of HSN migration. As a FOXO-Pak1 pathway was recently shown to regulate mammalian neuronal polarity, our findings indicate that the roles of FOXO and Pak1 in neuronal migration are likely conserved from C. elegans to higher organisms. PMID:23994474
Energy Technology Data Exchange (ETDEWEB)
Guo, Kong-Ming, E-mail: kmguo@xidian.edu.cn [School of Electromechanical Engineering, Xidian University, P.O. Box 187, Xi' an 710071 (China); Jiang, Jun, E-mail: jun.jiang@mail.xjtu.edu.cn [State Key Laboratory for Strength and Vibration, Xi' an Jiaotong University, Xi' an 710049 (China)
2014-07-04
To apply stochastic sensitivity function method, which can estimate the probabilistic distribution of stochastic attractors, to non-autonomous dynamical systems, a 1/N-period stroboscopic map for a periodic motion is constructed in order to discretize the continuous cycle into a discrete one. In this way, the sensitivity analysis of a cycle for discrete map can be utilized and a numerical algorithm for the stochastic sensitivity analysis of periodic solutions of non-autonomous nonlinear dynamical systems under stochastic disturbances is devised. An external excited Duffing oscillator and a parametric excited laser system are studied as examples to show the validity of the proposed method. - Highlights: • A method to analyze sensitivity of stochastic periodic attractors in non-autonomous dynamical systems is proposed. • Probabilistic distribution around periodic attractors in an external excited Φ{sup 6} Duffing system is obtained. • Probabilistic distribution around a periodic attractor in a parametric excited laser system is determined.
Functional Based Adaptive and Fuzzy Sliding Controller for Non-Autonomous Active Suspension System
Huang, Shiuh-Jer; Chen, Hung-Yi
In this paper, an adaptive sliding controller is developed for controlling a vehicle active suspension system. The functional approximation technique is employed to substitute the unknown non-autonomous functions of the suspension system and release the model-based requirement of sliding mode control algorithm. In order to improve the control performance and reduce the implementation problem, a fuzzy strategy with online learning ability is added to compensate the functional approximation error. The update laws of the functional approximation coefficients and the fuzzy tuning parameters are derived from the Lyapunov theorem to guarantee the system stability. The proposed controller is implemented on a quarter-car hydraulic actuating active suspension system test-rig. The experimental results show that the proposed controller suppresses the oscillation amplitude of the suspension system effectively.
Navier-Stokes-Voigt Equations with Memory in 3D Lacking Instantaneous Kinematic Viscosity
Di Plinio, Francesco; Giorgini, Andrea; Pata, Vittorino; Temam, Roger
2018-04-01
We consider a Navier-Stokes-Voigt fluid model where the instantaneous kinematic viscosity has been completely replaced by a memory term incorporating hereditary effects, in presence of Ekman damping. Unlike the classical Navier-Stokes-Voigt system, the energy balance involves the spatial gradient of the past history of the velocity rather than providing an instantaneous control on the high modes. In spite of this difficulty, we show that our system is dissipative in the dynamical systems sense and even possesses regular global and exponential attractors of finite fractal dimension. Such features of asymptotic well-posedness in absence of instantaneous high modes dissipation appear to be unique within the realm of dynamical systems arising from fluid models.
Adaptive sliding control of non-autonomous active suspension systems with time-varying loadings
Chen, Po-Chang; Huang, An-Chyau
2005-04-01
An adaptive sliding controller is proposed in this paper for controlling a non-autonomous quarter-car suspension system with time-varying loadings. The bound of the car-body loading is assumed to be available. Then, the reference coordinate is placed at the static position under the nominal loading so that the system dynamic equation is derived. Due to spring nonlinearities, the system property becomes asymmetric after coordinate transformation. Besides, in practical cases, system parameters are not easy to be obtained precisely for controller design. Therefore, in this paper, system uncertainties are lumped into two unknown time-varying functions. Since the variation bound of one of the unknown functions is not available, conventional adaptive schemes and robust designs are not applicable. To deal with this problem, the function approximation technique is employed to represent the unknown function as a finite combination of basis functions. The Lyapunov direct method can thus be used to find adaptive laws for updating coefficients in the approximating series and to prove stability of the closed-loop system. Since the position and velocity measurements of the unsprung mass are lumped into the unknown function, there is no need to install sensors on the axle and wheel assembly in the actual implementation. Simulation results are presented to show the performance of the proposed strategy.
The odd Voigt effect under a strong electric field in semiconductors
International Nuclear Information System (INIS)
Nguyen Hong Shon.
1991-08-01
The high frequency conductivity tensor σ ik (ω) in the linear approximation of magnetic field H and in the quadratic approximation of external dc electric field is derived by solving Boltzmann equation. The magneto-optical phenomena in the Voigt configuration (when a probe electro-magnetic wave propagates across a magnetic field) are investigated. It is shown that the birefringence and dichroism have a component that is odd (linear) in the magnetic fields and predominate over the even effect in the weak magnetic field. (author). 8 refs
International Nuclear Information System (INIS)
Kanna, T; Mareeswaran, R Babu; Tsitoura, F; Nistazakis, H E; Frantzeskakis, D J
2013-01-01
We study the dynamics of non-autonomous bright–dark matter-wave solitons in two- and three-component Bose–Einstein condensates. Our setting includes a time-dependent parabolic potential and scattering length, as well as Rabi coupling of the separate hyperfine states. By means of a similarity transformation, we transform the non-autonomous coupled Gross–Pitaevskii equations into the completely integrable Manakov model with defocusing nonlinearity, and construct the explicit form of the non-autonomous soliton solutions. The propagation characteristics for the one-soliton state, and collision scenarios for multiple soliton states are discussed in detail for two types of time-dependent nonlinearities: a kink-like one and a periodically modulated one, with appropriate time-dependence of the trapping potential. We find that in the two-component condensates the nature of soliton propagation is determined predominantly by the nature of the nonlinearity, as well as the temporal modulation of the harmonic potential; switching in this setting is essentially due to Rabi coupling. We also perform direct numerical simulation of the non-autonomous two-component coupled Gross–Pitaevskii equations to corroborate our analytical predictions. More interestingly, in the case of the three-component condensates, we find that the solitons can lead to collision-induced energy switching (energy sharing collision), that can be profitably used to control Rabi switching or vice versa. An interesting possibility of reversal of the nature of the constituent soliton, i.e., bright (dark) into dark (bright) due to Rabi coupling is demonstrated in the three-component setting. (paper)
Fractional Generalizations of Maxwell and Kelvin-Voigt Models for Biopolymer Characterization.
Directory of Open Access Journals (Sweden)
Bertrand Jóźwiak
Full Text Available The paper proposes a fractional generalization of the Maxwell and Kelvin-Voigt rheological models for a description of dynamic behavior of biopolymer materials. It was found that the rheological models of Maxwell-type do not work in the case of modeling of viscoelastic solids, and the model which significantly better describes the nature of changes in rheological properties of such media is the modified fractional Kelvin-Voigt model with two built-in springpots (MFKVM2. The proposed model was used to describe the experimental data from the oscillatory and creep tests of 3% (w/v kuzu starch pastes, and to determine the values of their rheological parameters as a function of pasting time. These parameters provide a lot of additional information about structure and viscoelastic properties of the medium in comparison to the classical analysis of dynamic curves G' and G" and shear creep compliance J(t. It allowed for a comprehensive description of a wide range of properties of kuzu starch pastes, depending on the conditions of pasting process.
Generalized Continuum: from Voigt to the Modeling of Quasi-Brittle Materials
Directory of Open Access Journals (Sweden)
Jamile Salim Fuina
2010-12-01
Full Text Available This article discusses the use of the generalized continuum theories to incorporate the effects of the microstructure in the nonlinear finite element analysis of quasi-brittle materials and, thus, to solve mesh dependency problems. A description of the problem called numerically induced strain localization, often found in Finite Element Method material non-linear analysis, is presented. A brief historic about the Generalized Continuum Mechanics based models is presented, since the initial work of Voigt (1887 until the more recent studies. By analyzing these models, it is observed that the Cosserat and microstretch approaches are particular cases of a general formulation that describes the micromorphic continuum. After reporting attempts to incorporate the material microstructure in Classical Continuum Mechanics based models, the article shows the recent tendency of doing it according to assumptions of the Generalized Continuum Mechanics. Finally, it presents numerical results which enable to characterize this tendency as a promising way to solve the problem.
Berk, Alexander
2013-03-01
Exact expansions for Voigt line-shape total, line-tail and spectral bin equivalent widths and for Voigt finite spectral bin single-line transmittances have been derived in terms of optical depth dependent exponentially-scaled modified Bessel functions of integer order and optical depth independent Fourier integral coefficients. The series are convergent for the full range of Voigt line-shapes, from pure Doppler to pure Lorentzian. In the Lorentz limit, the expansion reduces to the Ladenburg and Reiche function for the total equivalent width. Analytic expressions are derived for the first 8 Fourier coefficients for pure Lorentzian lines, for pure Doppler lines and for Voigt lines with at most moderate Doppler dependence. A strong-line limit sum rule on the Fourier coefficients is enforced to define an additional Fourier coefficient and to optimize convergence of the truncated expansion. The moderate Doppler dependence scenario is applicable to and has been implemented in the MODTRAN5 atmospheric band model radiative transfer software. Finite-bin transmittances computed with the truncated expansions reduce transmittance residuals compared to the former Rodgers-Williams equivalent width based approach by ∼2 orders of magnitude.
Sukhanov, AY
2017-02-01
We present an approximation Voigt contour for some parameters intervals such as the interval with y less than 0.02 and absolute value x less than 1.6 gives a simple formula for calculating and relative error less than 0.1%, and for some of the intervals suggetsted to use Hermite quadrature.
Directory of Open Access Journals (Sweden)
Azizollah Babakhani
2006-10-01
Full Text Available In the present paper we discuss the existence of positive solutions in the case of multi-term non-autonomous fractional differential equations with polynomial coefficients; the constant coefficient case has been studied in [2]. We consider the equation $$ Big(D^{alpha_n} -sum_{j = 1}^{n - 1} p_j(xD^{alpha_{n - j}}Bigy = f(x, y. $$ We state various conditions on $f$ and $p_j$'s under which this equation has: positive solutions, a unique solution which is positive, and a unique solution which may not be positive.
Optimized implementations of rational approximations for the Voigt and complex error function
International Nuclear Information System (INIS)
Schreier, Franz
2011-01-01
Rational functions are frequently used as efficient yet accurate numerical approximations for real and complex valued functions. For the complex error function w(x+iy), whose real part is the Voigt function K(x,y), code optimizations of rational approximations are investigated. An assessment of requirements for atmospheric radiative transfer modeling indicates a y range over many orders of magnitude and accuracy better than 10 -4 . Following a brief survey of complex error function algorithms in general and rational function approximations in particular the problems associated with subdivisions of the x, y plane (i.e., conditional branches in the code) are discussed and practical aspects of Fortran and Python implementations are considered. Benchmark tests of a variety of algorithms demonstrate that programming language, compiler choice, and implementation details influence computational speed and there is no unique ranking of algorithms. A new implementation, based on subdivision of the upper half-plane in only two regions, combining Weideman's rational approximation for small |x|+y<15 and Humlicek's rational approximation otherwise is shown to be efficient and accurate for all x, y.
Modeling ramp-hold indentation measurements based on Kelvin-Voigt fractional derivative model
Zhang, Hongmei; zhe Zhang, Qing; Ruan, Litao; Duan, Junbo; Wan, Mingxi; Insana, Michael F.
2018-03-01
Interpretation of experimental data from micro- and nano-scale indentation testing is highly dependent on the constitutive model selected to relate measurements to mechanical properties. The Kelvin-Voigt fractional derivative model (KVFD) offers a compact set of viscoelastic features appropriate for characterizing soft biological materials. This paper provides a set of KVFD solutions for converting indentation testing data acquired for different geometries and scales into viscoelastic properties of soft materials. These solutions, which are mostly in closed-form, apply to ramp-hold relaxation, load-unload and ramp-load creep-testing protocols. We report on applications of these model solutions to macro- and nano-indentation testing of hydrogels, gastric cancer cells and ex vivo breast tissue samples using an atomic force microscope (AFM). We also applied KVFD models to clinical ultrasonic breast data using a compression plate as required for elasticity imaging. Together the results show that KVFD models fit a broad range of experimental data with a correlation coefficient typically R 2 > 0.99. For hydrogel samples, estimation of KVFD model parameters from test data using spherical indentation versus plate compression as well as ramp relaxation versus load-unload compression all agree within one standard deviation. Results from measurements made using macro- and nano-scale indentation agree in trend. For gastric cell and ex vivo breast tissue measurements, KVFD moduli are, respectively, 1/3-1/2 and 1/6 of the elasticity modulus found from the Sneddon model. In vivo breast tissue measurements yield model parameters consistent with literature results. The consistency of results found for a broad range of experimental parameters suggest the KVFD model is a reliable tool for exploring intrinsic features of the cell/tissue microenvironments.
Zhang, Hongmei; Wang, Yue; Fatemi, Mostafa; Insana, Michael F.
2017-03-01
Kelvin-Voigt fractional derivative (KVFD) model parameters have been used to describe viscoelastic properties of soft tissues. However, translating model parameters into a concise set of intrinsic mechanical properties related to tissue composition and structure remains challenging. This paper begins by exploring these relationships using a biphasic emulsion materials with known composition. Mechanical properties are measured by analyzing data from two indentation techniques—ramp-stress relaxation and load-unload hysteresis tests. Material composition is predictably correlated with viscoelastic model parameters. Model parameters estimated from the tests reveal that elastic modulus E 0 closely approximates the shear modulus for pure gelatin. Fractional-order parameter α and time constant τ vary monotonically with the volume fraction of the material’s fluid component. α characterizes medium fluidity and the rate of energy dissipation, and τ is a viscous time constant. Numerical simulations suggest that the viscous coefficient η is proportional to the energy lost during quasi-static force-displacement cycles, E A . The slope of E A versus η is determined by α and the applied indentation ramp time T r. Experimental measurements from phantom and ex vivo liver data show close agreement with theoretical predictions of the η -{{E}A} relation. The relative error is less than 20% for emulsions 22% for liver. We find that KVFD model parameters form a concise features space for biphasic medium characterization that described time-varying mechanical properties. The experimental work was carried out at the Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA. Methodological development, including numerical simulation and all data analysis, were carried out at the school of Life Science and Technology, Xi’an JiaoTong University, 710049, China.
International Nuclear Information System (INIS)
Nouroz, F.
2015-01-01
Transposable elements (TEs) are capable of mobilizing from one genomic location to other, with changes in their copy numbers. Mutator-like elements (MULEs) are DNA transposons characterized by 9 bp target site duplications (TSDs), with high variability in sequence and length, and include non-conserved terminal inverted repeats (TIRs). We identified and characterized a family of Mutator-like elements designated as Shahroz. The structural and molecular analyses revealed that family had a small number of mostly defective non-autonomous MULEs and has shown limited activity in the evolutionary history of the Brassica A-genome. The Shahroz elements range in size from 2734 to 3160 bp including 76 bp imperfect TIRs and 9 bp variable TSDs. The individual copies have shown high homology (52-99%) in their entire lengths. The study revealed that the elements are less in numbers but active in Brassica rapa genomes and PCR amplification revealed their specificity and amplification in A-genome containing diploid and polyploids Brassica. The phylogenetic analysis of Brassica MULEs with other plant Mutator elements revealed that no correlation exists between Brassica MULEs and other elements suggesting a separate line of evolution. Analyzing the regions flanking the insertions revealed that the insertions have showed a preference for AT rich regions. The detailed study of these insertions revealed that although less in number and small sizes, they have played a role in Brassica genome evolution by their mobilization. (author)
Directory of Open Access Journals (Sweden)
Rebecca Josowitz
2016-09-01
Full Text Available Germline mutations in BRAF cause cardio-facio-cutaneous syndrome (CFCS, whereby 40% of patients develop hypertrophic cardiomyopathy (HCM. As the role of the RAS/MAPK pathway in HCM pathogenesis is unclear, we generated a human induced pluripotent stem cell (hiPSC model for CFCS from three patients with activating BRAF mutations. By cell sorting for SIRPα and CD90, we generated a method to examine hiPSC-derived cell type-specific phenotypes and cellular interactions underpinning HCM. BRAF-mutant SIRPα+/CD90− cardiomyocytes displayed cellular hypertrophy, pro-hypertrophic gene expression, and intrinsic calcium-handling defects. BRAF-mutant SIRPα−/CD90+ cells, which were fibroblast-like, exhibited a pro-fibrotic phenotype and partially modulated cardiomyocyte hypertrophy through transforming growth factor β (TGFβ paracrine signaling. Inhibition of TGFβ or RAS/MAPK signaling rescued the hypertrophic phenotype. Thus, cell autonomous and non-autonomous defects underlie HCM due to BRAF mutations. TGFβ inhibition may be a useful therapeutic option for patients with HCM due to RASopathies or other etiologies.
Aksikas, I.; Moghadam, A. Alizadeh; Forbes, J. F.
2018-04-01
This paper deals with the design of an optimal state-feedback linear-quadratic (LQ) controller for a system of coupled parabolic-hypebolic non-autonomous partial differential equations (PDEs). The infinite-dimensional state space representation and the corresponding operator Riccati differential equation are used to solve the control problem. Dynamical properties of the coupled system of interest are analysed to guarantee the existence and uniqueness of the solution of the LQ-optimal control problem and also to guarantee the exponential stability of the closed-loop system. Thanks to the eigenvalues and eigenfunctions of the parabolic operator and also the fact that the hyperbolic-associated operator Riccati differential equation can be converted to a scalar Riccati PDE, an algorithm to solve the LQ control problem has been presented. The results are applied to a non-isothermal packed-bed catalytic reactor. The LQ optimal controller designed in the early portion of the paper is implemented for the original non-linear model. Numerical simulations are performed to show the controller performances.
International Nuclear Information System (INIS)
Stamatiou, George; Ghikas, Demetris P.K.
2007-01-01
Properties related to entanglement in quantum systems, are known to be associated with distinct properties of the corresponding classical systems, as for example stability, integrability and chaos. This means that the detailed topology, both local and global, of the classical phase space may reveal, or influence, the entangling power of the quantum system. As it has been shown in the literature, the bifurcation points, in autonomous dynamical systems, play a crucial role for the onset of entanglement. Similarly, the existence of scars among the quantum states seems to be a factor in the dynamics of entanglement. Here we study these issues for a non-autonomous system, the quantum kicked top, as a collective model of a multi-qubit system. Using the bifurcation diagram of the corresponding classical limit (the classical kicked top), we analyzed the pair-wise and the bi-partite entanglement of the qubits and their relation to scars, as a function of the critical parameter of the system. We found that the pair-wise entanglement and pair-wise negativity show a strong maximum precisely at the bifurcation points, while the bi-partite entanglement changes slope at these points. We have also investigated the connection between entanglement and the fixed points on the branch of the bifurcation diagram between the two first bifurcation points and we found that the entanglement measures take their extreme values precisely on these points. We conjecture that our results on this behavior of entanglement is generic for many quantum systems with a nonlinear classical analogue
Schroeder, Paul J.; Cich, Matthew J.; Yang, Jinyu; Giorgetta, Fabrizio R.; Swann, William C.; Coddington, Ian; Newbury, Nathan R.; Drouin, Brian J.; Rieker, Gregory B.
2018-05-01
We measure speed-dependent Voigt lineshape parameters with temperature-dependence exponents for several hundred spectroscopic features of pure water spanning 6801-7188 cm-1. The parameters are extracted from broad bandwidth, high-resolution dual frequency comb absorption spectra with multispectrum fitting techniques. The data encompass 25 spectra ranging from 296 K to 1305 K and 1 to 17 Torr of pure water vapor. We present the extracted parameters, compare them to published data, and present speed-dependence, self-shift, and self-broadening temperature-dependent parameters for the first time. Lineshape data is extracted using a quadratic speed-dependent Voigt profile and a single self-broadening power law temperature-dependence exponent over the entire temperature range. The results represent an important step toward a new high-temperature database using advanced lineshape profiles.
Lalucque, Hervé; Malagnac, Fabienne; Green, Kimberly; Gautier, Valérie; Grognet, Pierre; Chan Ho Tong, Laetitia; Scott, Barry; Silar, Philippe
2017-01-15
Filamentous ascomycetes produce complex multicellular structures during sexual reproduction. Little is known about the genetic pathways enabling the construction of such structures. Here, with a combination of classical and reverse genetic methods, as well as genetic mosaic and graft analyses, we identify and provide evidence for key roles for two genes during the formation of perithecia, the sexual fruiting bodies, of the filamentous fungus Podospora anserina. Data indicate that the proteins coded by these two genes function cell-non-autonomously and that their activity depends upon conserved cysteines, making them good candidate for being involved in the transmission of a reactive oxygen species (ROS) signal generated by the PaNox1 NADPH oxidase inside the maturing fruiting body towards the PaMpk1 MAP kinase, which is located inside the underlying mycelium, in which nutrients are stored. These data provide important new insights to our understanding of how fungi build multicellular structures. Copyright © 2016 Elsevier Inc. All rights reserved.
Langa, José A.; Rodríguez-Bernal, Aníbal; Suárez, Antonio
In this paper we study in detail the geometrical structure of global pullback and forwards attractors associated to non-autonomous Lotka-Volterra systems in all the three cases of competition, symbiosis or prey-predator. In particular, under some conditions on the parameters, we prove the existence of a unique nondegenerate global solution for these models, which attracts any other complete bounded trajectory. Thus, we generalize the existence of a unique strictly positive stable (stationary) solution from the autonomous case and we extend to Lotka-Volterra systems the result for scalar logistic equations. To this end we present the sub-supertrajectory tool as a generalization of the now classical sub-supersolution method. In particular, we also conclude pullback and forwards permanence for the above models.
International Nuclear Information System (INIS)
Aghababa Mohammad Pourmahmood
2012-01-01
The centrifugal flywheel governor (CFG) is a mechanical device that automatically controls the speed of an engine and avoids the damage caused by sudden change of load torque. It has been shown that this system exhibits very rich and complex dynamics such as chaos. This paper investigates the problem of robust finite-time synchronization of non-autonomous chaotic CFGs. The effects of unknown parameters, model uncertainties and external disturbances are fully taken into account. First, it is assumed that the parameters of both master and slave CFGs have the same value and a suitable adaptive finite-time controller is designed. Second, two CFGs are synchronized with the parameters of different values via a robust adaptive finite-time control approach. Finally, some numerical simulations are used to demonstrate the effectiveness and robustness of the proposed finite-time controllers. (general)
Wijetunge, Chalini D; Saeed, Isaam; Boughton, Berin A; Roessner, Ute; Halgamuge, Saman K
2015-01-01
Mass Spectrometry (MS) is a ubiquitous analytical tool in biological research and is used to measure the mass-to-charge ratio of bio-molecules. Peak detection is the essential first step in MS data analysis. Precise estimation of peak parameters such as peak summit location and peak area are critical to identify underlying bio-molecules and to estimate their abundances accurately. We propose a new method to detect and quantify peaks in mass spectra. It uses dual-tree complex wavelet transformation along with Stein's unbiased risk estimator for spectra smoothing. Then, a new method, based on the modified Asymmetric Pseudo-Voigt (mAPV) model and hierarchical particle swarm optimization, is used for peak parameter estimation. Using simulated data, we demonstrated the benefit of using the mAPV model over Gaussian, Lorentz and Bi-Gaussian functions for MS peak modelling. The proposed mAPV model achieved the best fitting accuracy for asymmetric peaks, with lower percentage errors in peak summit location estimation, which were 0.17% to 4.46% less than that of the other models. It also outperformed the other models in peak area estimation, delivering lower percentage errors, which were about 0.7% less than its closest competitor - the Bi-Gaussian model. In addition, using data generated from a MALDI-TOF computer model, we showed that the proposed overall algorithm outperformed the existing methods mainly in terms of sensitivity. It achieved a sensitivity of 85%, compared to 77% and 71% of the two benchmark algorithms, continuous wavelet transformation based method and Cromwell respectively. The proposed algorithm is particularly useful for peak detection and parameter estimation in MS data with overlapping peak distributions and asymmetric peaks. The algorithm is implemented using MATLAB and the source code is freely available at http://mapv.sourceforge.net.
Moser, Elke; Grass, Dieter; Tragler, Gernot
Given the constantly raising world-wide energy demand and the accompanying increase in greenhouse gas emissions that pushes the progression of climate change, the possibly most important task in future is to find a carbon-low energy supply that finds the right balance between sustainability and energy security. For renewable energy generation, however, especially the second aspect turns out to be difficult as the supply of renewable sources underlies strong volatility. Further on, investment costs for new technologies are so high that competitiveness with conventional energy forms is hard to achieve. To address this issue, we analyze in this paper a non-autonomous optimal control model considering the optimal composition of a portfolio that consists of fossil and renewable energy and which is used to cover the energy demand of a small country. While fossil energy is assumed to be constantly available, the supply of the renewable resource fluctuates seasonally. We further on include learning effects for the renewable energy technology, which will underline the importance of considering the whole life span of such a technology for long-term energy planning decisions.
Hindle, Samantha; Afsari, Farinaz; Stark, Meg; Middleton, C. Adam; Evans, Gareth J.O.; Sweeney, Sean T.; Elliott, Christopher J.H.
2013-01-01
Parkinson's disease (PD) is associated with loss of dopaminergic signalling, and affects not just movement, but also vision. As both mammalian and fly visual systems contain dopaminergic neurons, we investigated the effect of LRRK2 mutations (the most common cause of inherited PD) on Drosophila electroretinograms (ERGs). We reveal progressive loss of photoreceptor function in flies expressing LRRK2-G2019S in dopaminergic neurons. The photoreceptors showed elevated autophagy, apoptosis and mitochondrial disorganization. Head sections confirmed extensive neurodegeneration throughout the visual system, including regions not directly innervated by dopaminergic neurons. Other PD-related mutations did not affect photoreceptor function, and no loss of vision was seen with kinase-dead transgenics. Manipulations of the level of Drosophila dLRRK suggest G2019S is acting as a gain-of-function, rather than dominant negative mutation. Increasing activity of the visual system, or of just the dopaminergic neurons, accelerated the G2019S-induced deterioration of vision. The fly visual system provides an excellent, tractable model of a non-autonomous deficit reminiscent of that seen in PD, and suggests that increased energy demand may contribute to the mechanism by which LRRK2-G2019S causes neurodegeneration. PMID:23396536
Badal, Martí; Xamena, Noel; Cabré, Oriol
2013-09-10
Most foldback elements are defective due to the lack of coding sequences but some are associated with coding sequences and may represent the entire element. This is the case of the NOF sequences found in the FB of Drosophila melanogaster, formerly considered as an autonomous TE and currently proposed as part of the so-called FB-NOF element, the transposon that would be complete and fully functional. NOF is always associated with FB and never seen apart from the FB inverted repeats (IR). This is the reason why the FB-NOF composite element can be considered the complete element. At least one of its ORFs encodes a protein that has always been considered its transposase, but no detailed studies have been carried out to verify this. In this work we test the hypothesis that FB-NOF is an active transposon nowadays. We search for its expression product, obtaining its cDNA, and propose the ORF and the sequence of its potential protein. We found that the NOF protein is not a transposase as it lacks any of the motifs of known transposases and also shows structural homology with hydrolases, therefore FB-NOF cannot belong to the superfamily MuDR/foldback, as up to now it has been classified, and can be considered as a non-autonomous transposable element. The alignment with the published genomes of 12 Drosophila species shows that NOF presence is restricted only to the 6 Drosophila species belonging to the melanogaster group. Copyright © 2013 Elsevier B.V. All rights reserved.
Hirschheydt, Monika von
2015-01-01
Arvustus: Nürnberg, Reiner, Höxtermann, Ekkehard, Voigt, Martina. Elisabeth Schiemann 1881-1972. Vom AußBruch der Genetik und der Frauen in den UmBrüchen des 20. Jahrhunderts. Beiträge eines Symposiums zum 200. Gründungsjubiläum der Humboldt-Universität Berlin. Rangsdorf: Basilisken-Presse 2014
On non-autonomous dynamical systems
Energy Technology Data Exchange (ETDEWEB)
Anzaldo-Meneses, A., E-mail: answald@ymail.com [Departamento de Ciencias Básicas, Universidad Autónoma Metropolitana, Distrito Federal 02200, México (Mexico)
2015-04-15
In usual realistic classical dynamical systems, the Hamiltonian depends explicitly on time. In this work, a class of classical systems with time dependent nonlinear Hamiltonians is analyzed. This type of problems allows to find invariants by a family of Veronese maps. The motivation to develop this method results from the observation that the Poisson-Lie algebra of monomials in the coordinates and momenta is clearly defined in terms of its brackets and leads naturally to an infinite linear set of differential equations, under certain circumstances. To perform explicit analytic and numerical calculations, two examples are presented to estimate the trajectories, the first given by a nonlinear problem and the second by a quadratic Hamiltonian with three time dependent parameters. In the nonlinear problem, the Veronese approach using jets is shown to be equivalent to a direct procedure using elliptic functions identities, and linear invariants are constructed. For the second example, linear and quadratic invariants as well as stability conditions are given. Explicit solutions are also obtained for stepwise constant forces. For the quadratic Hamiltonian, an appropriated set of coordinates relates the geometric setting to that of the three dimensional manifold of central conic sections. It is shown further that the quantum mechanical problem of scattering in a superlattice leads to mathematically equivalent equations for the wave function, if the classical time is replaced by the space coordinate along a superlattice. The mathematical method used to compute the trajectories for stepwise constant parameters can be applied to both problems. It is the standard method in quantum scattering calculations, as known for locally periodic systems including a space dependent effective mass.
Fermi acceleration in non-autonomous billiards
International Nuclear Information System (INIS)
Gelfreich, V; Turaev, D
2008-01-01
Fermi acceleration can be modelled by a classical particle moving inside a time-dependent domain and elastically reflecting from its boundary. In this paper, we describe how the results from the dynamical system theory can be used to explain the existence of trajectories with unbounded energy. In particular, we show for slowly oscillating boundaries that the energy of the particle may increase exponentially fast in time. (fast track communication)
Non-autonomous equations with unpredictable solutions
Akhmet, Marat; Fen, Mehmet Onur
2018-06-01
To make research of chaos more amenable to investigating differential and discrete equations, we introduce the concepts of an unpredictable function and sequence. The topology of uniform convergence on compact sets is applied to define unpredictable functions [1,2]. The unpredictable sequence is defined as a specific unpredictable function on the set of integers. The definitions are convenient to be verified as solutions of differential and discrete equations. The topology is metrizable and easy for applications with integral operators. To demonstrate the effectiveness of the approach, the existence and uniqueness of the unpredictable solution for a delay differential equation are proved as well as for quasilinear discrete systems. As a corollary of the theorem, a similar assertion for a quasilinear ordinary differential equation is formulated. The results are demonstrated numerically, and an application to Hopfield neural networks is provided. In particular, Poincaré chaos near periodic orbits is observed. The completed research contributes to the theory of chaos as well as to the theory of differential and discrete equations, considering unpredictable solutions.
Autonomous and non-autonomous traits mediate social cooperation ...
Indian Academy of Sciences (India)
2011-07-08
Jul 8, 2011 ... In the trishanku (triA−) mutant of the social amoeba Dictyostelium discoideum, aggregates are smaller than usual and the spore mass is located mid-way up the stalk, not at the apex. We have monitored aggregate territory size, spore allocation and fruiting body morphology in chimaeric groups of ...
Maximal regularity for non-autonomous stochastic evolution ...
Indian Academy of Sciences (India)
Tôn Vi?t T?
2017-11-17
Nov 17, 2017 ... in a separable UMD Banach space E of type 2 with norm. ·. Here, W denotes a ... cases, e.g., the case where A is a bounded linear operator [3]. .... measurable if it is the pointwise limit of a sequence of simple functions. .... Here, Fβ,σ ((0, T]; E) denotes a weighted Hölder continuous function space introduced.
Non-standard connections for non-autonomous systems
International Nuclear Information System (INIS)
Echeverria, A.; Munoz, M.C.; Roman, N.
1995-01-01
Dealing with the jet-bundle description of time-dependent classical mechanics, we prove that there are some elements, such as the Lagrangian energy and the construction of the Hamiltonian formalism, whose definition requires the previous choice of a connection. This is the same situation than in the jet-bundle description of first-order classical field theories although, in mechanics, this connection-dependence is usually hidden by the use of the natural connection given by the trivial bundle structure of the phase spaces in consideration. However, we also prove that this dependence is dynamically irrelevant. 7 refs
Novel non-autonomous transposable elements on W chromosome ...
Indian Academy of Sciences (India)
2010-09-06
Sep 6, 2010 ... Development as a female is determined by the ... element is believed to be analogous to the human Alu ele- ment. Numerous SINEs have ... designated as p50-library and C108-library, were also con- structed using genomic ...
Hepatitis C - a South African perspective | Voigt | South African ...
African Journals Online (AJOL)
Sequence analysis and expression of the RNA has shown it to be closely related to the flavi- and pestiviruses. It has marked genomic variability which may affect its biological and immunological characteristics, is transmitted parenterally and sporadically, by as yet unidentified routes, and causes chronic indolent liver ...
Stability analysis of non-autonomous reaction-diffusion systems: the effects of growing domains
Madzvamuse, Anotida; Gaffney, Eamonn A.; Maini, Philip K.
2009-01-01
By using asymptotic theory, we generalise the Turing diffusively-driven instability conditions for reaction-diffusion systems with slow, isotropic domain growth. There are two fundamental biological differences between the Turing conditions on fixed and growing domains, namely: (i) we need not enforce cross nor pure kinetic conditions and (ii) the restriction to activator-inhibitor kinetics to induce pattern formation on a growing biological system is no longer a requirement. Our theoretical findings are confirmed and reinforced by numerical simulations for the special cases of isotropic linear, exponential and logistic growth profiles. In particular we illustrate an example of a reaction-diffusion system which cannot exhibit a diffusively-driven instability on a fixed domain but is unstable in the presence of slow growth. © Springer-Verlag 2009.
Dynamical properties of a non-autonomous bouncing ball model forced by non-harmonic excitation
Czech Academy of Sciences Publication Activity Database
Lampart, M.; Zapoměl, Jaroslav
2016-01-01
Roč. 39, č. 16 (2016), s. 4923-4929 ISSN 0170-4214 R&D Projects: GA ČR GA15-06621S Institutional support: RVO:61388998 Keywords : bifurcation * chaos tests * mechanical model Subject RIV: BI - Acoustics Impact factor: 1.017, year: 2016
Stability analysis of non-autonomous reaction-diffusion systems: the effects of growing domains
Madzvamuse, Anotida
2009-08-29
By using asymptotic theory, we generalise the Turing diffusively-driven instability conditions for reaction-diffusion systems with slow, isotropic domain growth. There are two fundamental biological differences between the Turing conditions on fixed and growing domains, namely: (i) we need not enforce cross nor pure kinetic conditions and (ii) the restriction to activator-inhibitor kinetics to induce pattern formation on a growing biological system is no longer a requirement. Our theoretical findings are confirmed and reinforced by numerical simulations for the special cases of isotropic linear, exponential and logistic growth profiles. In particular we illustrate an example of a reaction-diffusion system which cannot exhibit a diffusively-driven instability on a fixed domain but is unstable in the presence of slow growth. © Springer-Verlag 2009.
A fast computing method to distinguish the hyperbolic trajectory of an non-autonomous system
Jia, Meng; Fan, Yang-Yu; Tian, Wei-Jian
2011-03-01
Attempting to find a fast computing method to DHT (distinguished hyperbolic trajectory), this study first proves that the errors of the stable DHT can be ignored in normal direction when they are computed as the trajectories extend. This conclusion means that the stable flow with perturbation will approach to the real trajectory as it extends over time. Based on this theory and combined with the improved DHT computing method, this paper reports a new fast computing method to DHT, which magnifies the DHT computing speed without decreasing its accuracy. Project supported by the National Natural Science Foundation of China (Grant No. 60872159).
A fast computing method to distinguish the hyperbolic trajectory of an non-autonomous system
International Nuclear Information System (INIS)
Jia Meng; Fan Yang-Yu; Tian Wei-Jian
2011-01-01
Attempting to find a fast computing method to DHT (distinguished hyperbolic trajectory), this study first proves that the errors of the stable DHT can be ignored in normal direction when they are computed as the trajectories extend. This conclusion means that the stable flow with perturbation will approach to the real trajectory as it extends over time. Based on this theory and combined with the improved DHT computing method, this paper reports a new fast computing method to DHT, which magnifies the DHT computing speed without decreasing its accuracy. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)
Spreading the word: non-autonomous effects of apoptosis during development, regeneration and disease
Pérez-Garijo, Ainhoa; Steller, Hermann
2015-01-01
Apoptosis, in contrast to other forms of cell death such as necrosis, was originally regarded as a ‘silent’ mechanism of cell elimination designed to degrade the contents of doomed cells. However, during the past decade it has become clear that apoptotic cells can produce diverse signals that have a profound impact on neighboring cells and tissues. For example, apoptotic cells can release factors that influence the proliferation and survival of adjacent tissues. Apoptosis can also affect tissue movement and morphogenesis by modifying tissue tension in surrounding cells. As we review here, these findings reveal unexpected roles for apoptosis in tissue remodeling during development, as well as in regeneration and cancer. PMID:26443630
Apoptotic cells can induce non-autonomous apoptosis through the TNF pathway
Pérez-Garijo, Ainhoa; Fuchs, Yaron; Steller, Hermann
2013-01-01
Apoptotic cells can produce signals to instruct cells in their local environment, including ones that stimulate engulfment and proliferation. We identified a novel mode of communication by which apoptotic cells induce additional apoptosis in the same tissue. Strong induction of apoptosis in one compartment of the Drosophila wing disc causes apoptosis of cells in the other compartment, indicating that dying cells can release long-range death factors. We identified Eiger, the Drosophila tumor necrosis factor (TNF) homolog, as the signal responsible for apoptosis-induced apoptosis (AiA). Eiger is produced in apoptotic cells and, through activation of the c-Jun N-terminal kinase (JNK) pathway, is able to propagate the initial apoptotic stimulus. We also show that during coordinated cell death of hair follicle cells in mice, TNF-α is expressed in apoptotic cells and is required for normal cell death. AiA provides a mechanism to explain cohort behavior of dying cells that is seen both in normal development and under pathological conditions. DOI: http://dx.doi.org/10.7554/eLife.01004.001 PMID:24066226
Predicting catastrophes of non-autonomous networks with visibility graphs and horizontal visibility
Zhang, Haicheng; Xu, Daolin; Wu, Yousheng
2018-05-01
Prediction of potential catastrophes in engineering systems is a challenging problem. We first attempt to construct a complex network to predict catastrophes of a multi-modular floating system in advance of their occurrences. Response time series of the system can be mapped into an virtual network by using visibility graph or horizontal visibility algorithm. The topology characteristics of the networks can be used to forecast catastrophes of the system. Numerical results show that there is an obvious corresponding relationship between the variation of topology characteristics and the onset of catastrophes. A Catastrophe Index (CI) is proposed as a numerical indicator to measure a qualitative change from a stable state to a catastrophic state. The two approaches, the visibility graph and horizontal visibility algorithms, are compared by using the index in the reliability analysis with different data lengths and sampling frequencies. The technique of virtual network method is potentially extendable to catastrophe predictions of other engineering systems.
International Nuclear Information System (INIS)
Struckmeier, Juergen
2005-01-01
We will present a consistent description of Hamiltonian dynamics on the 'symplectic extended phase space' that is analogous to that of a time-independent Hamiltonian system on the conventional symplectic phase space. The extended Hamiltonian H 1 and the pertaining extended symplectic structure that establish the proper canonical extension of a conventional Hamiltonian H will be derived from a generalized formulation of Hamilton's variational principle. The extended canonical transformation theory then naturally permits transformations that also map the time scales of the original and destination system, while preserving the extended Hamiltonian H 1 , and hence the form of the canonical equations derived from H 1 . The Lorentz transformation, as well as time scaling transformations in celestial mechanics, will be shown to represent particular canonical transformations in the symplectic extended phase space. Furthermore, the generalized canonical transformation approach allows us to directly map explicitly time-dependent Hamiltonians into time-independent ones. An 'extended' generating function that defines transformations of this kind will be presented for the time-dependent damped harmonic oscillator and for a general class of explicitly time-dependent potentials. In the appendix, we will re-establish the proper form of the extended Hamiltonian H 1 by means of a Legendre transformation of the extended Lagrangian L 1
On the unbounded behaviour for some non-autonomous systems in Banach spaces
International Nuclear Information System (INIS)
Djafari Rouhani, B.
1991-09-01
By modifying our previous methods and by using the notion of integral solution introduced by Benilan, we study the asymptotic behaviour of unbounded trajectories for the quasi-autonomous dissipative system: du/dt + Au is not an element of f where X is a real Banach space, A an accretive (possibly multivalued) operator in X x X, and f - f ∞ is an element of L p ((0, +∞);X) for some f ∞ is an element of X and 1 ≤ p < ∞. (author). 24 refs
Voigt modelling of size–strain analysis: Application to α-Al2O3 ...
Indian Academy of Sciences (India)
Unknown
urea mixture, annealed samples and commercial α-Al2O3 sample. It is likely from the ... used for line broadening studies, the Stokes deconvolu- tion (Stokes 1948) ... unbiased approach to obtain the 'true specimen broad- ened' profile ... Experimental ... the Warren–Averbach method, simplified integral breadth method and ...
Numerical implementation of Voigt and Maxwell models for simulation of waves in the ground
Directory of Open Access Journals (Sweden)
Sheshenin Sergey Vladimirovich
2014-12-01
Full Text Available A lot of papers have been dedicated to simulation of dynamic processes in soil and underground structures. For example, some authors considered wave distribution in underground water pipes for creation of vibration monitoring system, others considered theoretical and algorithm aspects of efficient implementation of realistic seismic wave attenuation due to viscosity development with the help of Finite Difference Method, etc. The paper describes the numerical simulation, designed for simulation of the stress-strain state in the ground subjected to wave processes. We consider the ground with a concrete structure immersed in. The purpose of the work is the description of small vibrations in hard soil, which can nevertheless make undesirable impact on the objects in the ground or on the surface. Explicit Wilkins type scheme is used for time integration. It has proven to be successful, including the use in a well-known LS-DYNA code. As a result we created our own computer code based on the finite element method (FEM. An example of its practical usage is given.
Nudge, Embarrassment, and Restriction—Replies to Voigt, Tieffenbach, and Saghai
Directory of Open Access Journals (Sweden)
Nir Eyal
2015-01-01
Full Text Available It is a privilege that some of the most promising contributors to public health ethics took the time to think and comment on my op-ed. Kristin Voigt’s (1, Emma Tieffenbach’s (2, and Yashar Saghai’s (3 ingenious comments have taught me a lot about nudging, embarrassment, and restriction. Let me address their main points one by one.
Translating ancient Greek aspect: Sappho's Fr. 1 Voigt / Janika Päll
Päll, Janika, 1965-
2007-01-01
Vana-kreeka keele aspektist, selle kasutamisest ja tõlkimisprobleemidest Sappho luuletuse tõlkeid analüüsides. Lisas toodud ka Sappho luuletus originaalkeeles, tõlked ladina, eesti, inglise, saksa, itaalia, prantsuse ja vene keelde
International Nuclear Information System (INIS)
Fang, Hsin-Yu; Greten, Florian R.
2011-01-01
Genetic studies describing a link between cancer and inflammation have increased recently. Activation of the transcription factor nuclear factor-κB (NF-κB) and its effector pathways has been proposed to be the missing link between these two processes. NF-κB is persistently activated in several types of tumors. However, NF-κB has a distinct role in cancer cells and in inflammatory cells. While in tumor cells NF-κB controls cell survival, in inflammatory cells NF-κB activates genes that encode pro-inflammatory cytokines which further act in a paracrine manner within the tumor microenvironment to contribute to tumorigenesis. Inactivation of NF-κB can also reduce chemoresistance and radioresistance of cancer cells. Therefore, specific NF-κB inhibition in combination with cytotoxic drugs and/or irradiation represents a very promising strategy for cancer therapy
The study of protein adsorption on the membrane surface is of great importance to cheese-making processors that use polymeric membrane-based processes to recover whey protein from the process waste streams. Quartz crystal microbalance with dissipation (QCM-D) is a lab-scale, fast analytical techniq...
DEFF Research Database (Denmark)
Alstrøm, Tommy Sonne; Schmidt, Mikkel Nørgaard; Rindzevicius, Tomas
2017-01-01
Raman spectroscopy is a well-known analytical technique for identifying and analyzing chemical species. Since Raman scattering is a weak effect, surface-enhanced Raman spectroscopy (SERS) is often employed to amplify the signal. SERS signal surface mapping is a common method for detecting trace...... to directly and reliably identify the Raman modes, with overall performance similar to the state of the art non-negative matrix factorization approach. However, the model provides better interpretation and is a step towards enabling the use of SERS in detection of trace amounts of molecules in real-life...
Der moderne Staat : ein Glanzstück europäischer Form und occidentalen Rationalismus / Rüdiger Voigt
Voigt, Rüdiger
2014-01-01
Modernsest riigist, antiikse riigikunsti taassünnist, erinevatest riigiteooriatest (Machiavelli, Bodin, Hobbes, Locke, Montesquieu, Rousseau, Kant, Hegel, Marx, Jellinek, Weber, Habermas, Foucault, Agamben), globaliseerumise väljakutsetest, ohtudest, riigi tulevikust
Directory of Open Access Journals (Sweden)
M. A. A. K. Munasinghe
2011-01-01
Full Text Available Background. Role of herbs in the management and control of diabetes has emerged fast over the years. We assessed the efficacy of Coccinia grandis (locally known as Ken, Kovakka leaves as a hypoglycemic agent. Methods. Double-blind phase I clinical trial was conducted at the general hospital and a private hospital in Matara in August 2009. All the participants were given a common meal for dinner, and they maintained a 10-hour fasting period. Sixty-one healthy volunteers were given a meal containing 20 g of leaves of Coccinia grandis which was mixed with a measured amount of scraped coconut and table salt for breakfast, and other 61 were given the placebo meal which also contained scraped coconut and salt. Glucose tolerance test was performed blindly for the two groups. Mixed factorial design analysis of variance and student's t-test were applied. Results. Overall blood sugar levels of the experimental group were also significantly lower than those of the control group (F(1,117 5.56, <0.05. Increase in the blood sugar levels from fasting to one hour (F(1,117 6.77, <0.05 and two hours (F(1,117 5.28, <0.05 postprandially was statistically significant for participants who were in the control group than those of in the experimental group. The mean difference of postprandial blood sugar levels (mg/dL after one hour (20.2, 95% confidence interval, 4.81 to 35.5 and two hours (11.46, 95% confidence interval; 1.03 to 21.9 was statistically significant between the two groups. Conclusions. Coccinia grandis has a blood sugar lowering effect. However further studies are needed to validate our findings.
Wang, Lu; Peng, Qian; Zhao, Jianbo; Ren, Fei; Zhou, Hui; Wang, Wei; Liao, Liao; Owiti, Albert; Jiang, Quan; Han, Yuepeng
2016-05-01
Transposable elements account for approximately 30 % of the Prunus genome; however, their evolutionary origin and functionality remain largely unclear. In this study, we identified a hAT transposon family, termed Moshan, in Prunus. The Moshan elements consist of three types, aMoshan, tMoshan, and mMoshan. The aMoshan and tMoshan types contain intact or truncated transposase genes, respectively, while the mMoshan type is miniature inverted-repeat transposable element (MITE). The Moshan transposons are unique to Rosaceae, and the copy numbers of different Moshan types are significantly correlated. Sequence homology analysis reveals that the mMoshan MITEs are direct deletion derivatives of the tMoshan progenitors, and one kind of mMoshan containing a MuDR-derived fragment were amplified predominately in the peach genome. The mMoshan sequences contain cis-regulatory elements that can enhance gene expression up to 100-fold. The mMoshan MITEs can serve as potential sources of micro and long noncoding RNAs. Whole-genome re-sequencing analysis indicates that mMoshan elements are highly active, and an insertion into S-haplotype-specific F-box gene was reported to cause the breakdown of self-incompatibility in sour cherry. Taken together, all these results suggest that the mMoshan elements play important roles in regulating gene expression and driving genomic structural variation in Prunus.
Ciancio, V.; Turrisi, E.; Kluitenberg, G.A.
1986-01-01
In a previous paper the propagation of linear longitudinal acoustic waves in isotropic media with shear and volume viscosity and a tensorial internal variable was considered and the expressions for the velocity and attenuation of the waves were obtained. In the present paper we investigate the
Turrisi, E.; Ciancio, V.; Kluitenberg, G.A.
1982-01-01
The propagation of linear transverse acoustic waves in isotropic media in which mechanical relaxation phenomena occur was considered in a previous paper. In particular expressions for the velocity and attenuation of the waves were obtained and the limiting cases of waves with high and low
Bulk magnetic properties of CdFe2 O4 in nano-regime
Indian Academy of Sciences (India)
TECS
In recent years, the design and synthesis of nano-magnetic particles ... 1998). Two different types of spin structure were suggested .... rule integration of the pseudo-Voigt function. ... differences between measured and calculated values) that.
Energy Technology Data Exchange (ETDEWEB)
2017-09-01
Nmrfit reads the output from a nuclear magnetic resonance (NMR) experiment and, through a number of intuitive API calls, produces a least-squares fit of Voigt-function approximations via particle swarm optimization.
FASCODE - Fast Atmospheric Signature Code (Spectral Transmittance and Radiance)
1978-01-16
cA6 Approvued o ulcrlae distrnibuin nimtd I? OSTIUTIN TAEMNT(. te ~FrAc1aieW iRD ADDRES 10- iiON 1diE$@NT.t haul fl TASK VIS. dn IPLM nTAR viNOT...the Voigt line shape profile model discussed above. In addition, the Voigt model provides a proper treatment of the transition region at those
Algorithm of constructing hybrid effective modules for elastic isotropic composites
Svetashkov, A. A.; Miciński, J.; Kupriyanov, N. A.; Barashkov, V. N.; Lushnikov, A. V.
2017-02-01
The algorithm of constructing of new effective elastic characteristics of two-component composites based on the superposition of the models of Reiss and Voigt, Hashin and Strikman, as well as models of the geometric average for effective modules. These effective characteristics are inside forks Voigt and Reiss. Additionally, the calculations of the stress-strain state of composite structures with new effective characteristics give more accurate prediction than classical models do.
Autonomy of imagery and production of original verbal images.
Khatena, J
1976-08-01
90 college students (31 men and 59 women) were categorized as moderately autonomous, less autonomous (less highly controlled) and non-autonomous (high controlled) imagers according to the Gordon Test of Visual Imagery Control Moderately autonomous imagers produced significantly more original verbal images than less autonomous and non-autonomous imagers with less autonomous imagers scoring higher than non-autonomous imagers as measured by Onomatopoeia and Images. There were no significant sex main effects of interaction of autonomy of imagery level X sex.
Proceedings – Mathematical Sciences | Indian Academy of Sciences
Indian Academy of Sciences (India)
Maximal regularity for non-autonomous stochastic evolution equations in UMD ... The abstract results are then applied to a stochastic partial differential equation. ... Japan; Department of Applied Physics, Graduate School of Engineering, ...
Reduction of symplectic principal R-bundles
International Nuclear Information System (INIS)
Lacirasella, Ignazio; Marrero, Juan Carlos; Padrón, Edith
2012-01-01
We describe a reduction process for symplectic principal R-bundles in the presence of a momentum map. These types of structures play an important role in the geometric formulation of non-autonomous Hamiltonian systems. We apply this procedure to the standard symplectic principal R-bundle associated with a fibration π:M→R. Moreover, we show a reduction process for non-autonomous Hamiltonian systems on symplectic principal R-bundles. We apply these reduction processes to several examples. (paper)
Skinner-Rusk unified formalism for higher-order systems
Prieto-Martínez, Pedro Daniel; Román-Roy, Narciso
2012-07-01
The Lagrangian-Hamiltonian unified formalism of R. Skinner and R. Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, first-order and higher-order field theories, and higher-order autonomous systems. In this work we present a generalization of this formalism for higher-order non-autonomous mechanical systems.
International Nuclear Information System (INIS)
Chen Yun; Wu Xiaofeng; Liu Zhong
2009-01-01
This paper studies global synchronization of non-autonomous chaotic electro-mechanical gyrostat systems via variable substitution control. A master-slave non-autonomous synchronization scheme with variable substitution control is mathematically presented. Based on the scheme, some sufficient algebraic criteria for global chaos synchronization of master and slave electro-mechanical gyrostat systems via various single-variable coupling are derived. The effectiveness of the obtained criteria is numerically illustrated by the examples.
Directory of Open Access Journals (Sweden)
Wendy B Iser
2011-03-01
Full Text Available Insulin/IGF-I-like signaling (IIS has both cell autonomous and non-autonomous functions. In some cases, targets through which IIS regulates cell-autonomous functions, such as cell growth and metabolism, have been identified. In contrast, targets for many non-autonomous IIS functions, such as C. elegans dauer morphogenesis, remain elusive. Here, we report the use of genomic and genetic approaches to identify potential non-autonomous targets of C. elegans IIS. First, we used transcriptional microarrays to identify target genes regulated non-autonomously by IIS in the intestine or in neurons. C. elegans IIS controls expression of a number of stress response genes, which were differentially regulated by tissue-restricted IIS. In particular, expression of sod-3, a MnSOD enzyme, was not regulated by tissue-restricted IIS on the microarrays, while expression of hsp-16 genes was rescued back to wildtype by tissue restricted IIS. One IIS target regulated non-autonomously by age-1 was cyp-35B1/dod-13, encoding a cytochrome P450. Genetic analysis of the cyp-35B1 promoter showed both DAF-16 and HSF-1 are direct regulators. Based on these findings, we propose that hsf-1 may participate in the pathways mediating non-autonomous activities of age-1 in C. elegans.
Iser, Wendy B; Wilson, Mark A; Wood, William H; Becker, Kevin; Wolkow, Catherine A
2011-03-09
Insulin/IGF-I-like signaling (IIS) has both cell autonomous and non-autonomous functions. In some cases, targets through which IIS regulates cell-autonomous functions, such as cell growth and metabolism, have been identified. In contrast, targets for many non-autonomous IIS functions, such as C. elegans dauer morphogenesis, remain elusive. Here, we report the use of genomic and genetic approaches to identify potential non-autonomous targets of C. elegans IIS. First, we used transcriptional microarrays to identify target genes regulated non-autonomously by IIS in the intestine or in neurons. C. elegans IIS controls expression of a number of stress response genes, which were differentially regulated by tissue-restricted IIS. In particular, expression of sod-3, a MnSOD enzyme, was not regulated by tissue-restricted IIS on the microarrays, while expression of hsp-16 genes was rescued back to wildtype by tissue restricted IIS. One IIS target regulated non-autonomously by age-1 was cyp-35B1/dod-13, encoding a cytochrome P450. Genetic analysis of the cyp-35B1 promoter showed both DAF-16 and HSF-1 are direct regulators. Based on these findings, we propose that hsf-1 may participate in the pathways mediating non-autonomous activities of age-1 in C. elegans.
Muhsen, Mahmod; Ohi, Kota; Aoki, Hiroshi; Ikeda, Hidetoshi; Fukusho, Akio
2013-03-01
A new, reliable and secure virus assay method, named the competitive virus assay (CVA) method, has been established for the titration of bovine viral diarrhea viruses (BVDVs) that either show the exaltation of Newcastle disease virus (END) phenomenon or heterologous interference phenomenon (but not the END phenomenon). This method is based on the principle of (1) homologous interference between BVDVs, by using BVDV RK13/E(-) or BVDV RK13/E(+) strains as competitor virus, and (2) END phenomenon and heterologous interference, by using attenuated Newcastle disease virus (NDV) TCND strain as challenge virus. In titration of BVDV END(+) and BVDV END(-) viruses, no significant difference in estimated virus titer was observed between CVA and conventional methods. CVA method demonstrated comparable levels of sensitivity and accuracy as conventional END and interference methods, which require the use of a velogenic Miyadera strain of NDV and vesicular stomatitis virus (VSV), both of which are agents of high-risk diseases. As such, the CVA method is a safer alternative, with increased bio-safety and bio-containment, through avoidance of virulent strains that are commonly employed with conventional methods. Copyright © 2012 Elsevier B.V. All rights reserved.
Validation of the measurement model concept for error structure identification
International Nuclear Information System (INIS)
Shukla, Pavan K.; Orazem, Mark E.; Crisalle, Oscar D.
2004-01-01
The development of different forms of measurement models for impedance has allowed examination of key assumptions on which the use of such models to assess error structure are based. The stochastic error structures obtained using the transfer-function and Voigt measurement models were identical, even when non-stationary phenomena caused some of the data to be inconsistent with the Kramers-Kronig relations. The suitability of the measurement model for assessment of consistency with the Kramers-Kronig relations, however, was found to be more sensitive to the confidence interval for the parameter estimates than to the number of parameters in the model. A tighter confidence interval was obtained for Voigt measurement model, which made the Voigt measurement model a more sensitive tool for identification of inconsistencies with the Kramers-Kronig relations
Modeling the mechanical properties of liver fibrosis in rats.
Zhu, Ying; Chen, Xin; Zhang, Xinyu; Chen, Siping; Shen, Yuanyuan; Song, Liang
2016-06-14
The progression of liver fibrosis changes the biomechanical properties of liver tissue. This study characterized and compared different liver fibrosis stages in rats in terms of viscoelasticity. Three viscoelastic models, the Voigt, Maxwell, and Zener models, were applied to experimental data from rheometer tests and then the elasticity and viscosity were estimated for each fibrosis stage. The study found that both elasticity and viscosity are correlated with the various stages of liver fibrosis. The study revealed that the Zener model is the optimal model for describing the mechanical properties of each fibrosis stage, but there is no significant difference between the Zener and Voigt models in their performance on liver fibrosis staging. Therefore the Voigt model can still be effectively used for liver fibrosis grading. Copyright © 2016 Elsevier Ltd. All rights reserved.
Laser line shape and spectral density of frequency noise
International Nuclear Information System (INIS)
Stephan, G.M.; Blin, S.; Besnard, P.; Tam, T.T.; Tetu, M.
2005-01-01
Published experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise
A theory of piezoelectric laminates
International Nuclear Information System (INIS)
Giangreco, E.
1997-01-01
A theory of piezoelectric laminates is rationally derived from the three-dimensional Voigt theory of piezoelectricity. The present theory is a generalization to piezoelectric laminates of the Reissner-Mindlin-type layer-wise theory of elastic laminates. Both a differential formulation and a variational formulation of the piezoelectric laminate problem are presented. The proposed theory is adopted in the analysis of simple problems, in order to verify its effectiveness. The results it provides turn out to be in good agreement with the results supplied by the Voigt theory of piezoelectricity
Transitions in the surface energy balance during the life cycle of a ...
Indian Academy of Sciences (India)
Computations are all illustrated for a box over central India where the coastal effects were small, data .... water vapor-carbon dioxide overlap and of a Voigt ... and long wave emission from the Planck equation .... into the inland regions. By the ...
International Nuclear Information System (INIS)
Manne, Jagadeeshwari; Bui, Thinh Q.; Webster, Christopher R.
2017-01-01
Molecular line parameters of foreign- broadening by air, carbon dioxide, and helium gas have been experimentally determined for infrared ro-vibrational spectral lines of methane isotopologues ("1"2CH_4 and "1"3CH_4) at 3057 cm"−"1 targeted by the Tunable Laser Spectrometer (TLS) in the Sample Analysis at Mars (SAM) instrument suite on the Mars Science Laboratory (MSL) Curiosity rover. From multi-spectrum analyses with the speed-dependent Voigt line profile with Rosenkrantz line-mixing, speed-dependence and line-mixing effects were quantified for methane spectra at total pressures up to 200 mbar. The fitted air-broadening coefficients deviated from 8–25% to those reported in the HITRAN-2012 database. - Highlights: • Measurements of foreign broadening coefficients for Mars-TLS specific methane lines. • Spectral parameters were deduced from Speed-dependent Voigt profile with line mixing effects taken into account. • A thorough comparison of different line profile fits for the Mars-TLS methane lines. The fitted broadening coefficients and areas deviated up to 30% and 4%, respectively, when comparing the speed-dependent Voigt profile (with Rosenkrantz line-mixing) with the simplest Voigt profile. • Foreign broadening coefficients were measured within a precision of 2.2%.
Tc-99m Labeled and VIP-Receptor Targeted Liposomes for Effective Imaging of Breast Cancer
2006-09-01
1997) 111–118. Treat. 65 (1) (2001) 49–54. [20] X . Yang, L.H. Young, J.M. Voigt, Expression of a vitamin [5] S . Dagar, M. Sekosan, B.S. Lee, I...aggregation ( k3 is significantly reduced).Firstly, if PEGylated phospholipid nanomicelles are present in the extracellular milieu when Ab-42 is cleaved, Ab-42
Czech Academy of Sciences Publication Activity Database
Smyčka, Václav
2016-01-01
Roč. 139, 1/2 (2016), s. 25-49 ISSN 0024-4457 R&D Projects: GA ČR GAP406/12/2254 Institutional support: RVO:67985955 Keywords : Nikolaus Adaukt Voigt * Ignaz Born * Franz Martin Pelzel * Ludwig Zehnmark * metaphor * knowledge * temporality Subject RIV: AB - History
Synthesis and structure refinement of layered double hydroxides of ...
Indian Academy of Sciences (India)
Administrator
years because of their potential applications in catalysis. (Cavani et al 1991), ion .... LDHs, the modified psuedo-Voigt line shape function with five variables (U, V, ..... Thomas G S, Rajamathi M and Kamath P V 2004 Clays Clay. Miner. 52 693.
Robertson-Walker solutions for various types of energy-momentum tensor
International Nuclear Information System (INIS)
Lukacs, B.
1976-01-01
Robertson-Walker solutions are important in general relativity as universe solutions. This paper contains a number of Robertson-Walker-type solutions for certain cases, namely, for noncharged massless scalar meson fields, viscous fluids, Hookean elastic mediums, and Kelvin-Voigt viscoelastic systems. (author)
The elastic constants and anisotropy of superconducting MgCNi3 and CdCNi3 under different pressure
Feng, Huifang; Wu, Xiaozhi; Gan, Liyong; Wang, Rui; Wei, Qunyi
2013-01-01
The second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of MgCNi3 and CdCNi3 are presented by using first-principles methods combined with homogeneous deformation theory. The Voigt-Reuss-Hill (VRH) approximation are used
Dispersion relation for localized magnetic polaritons propagating at ...
Indian Academy of Sciences (India)
Abstract. Localized magnetic polaritons are investigated in the systems consisting of two magnetic superlattices, coupled by a ferromagnetic contact layer. The general dis- persion relation for localized magnetic polaritons are derived in the framework of the electromagnetic wave theory in the Voigt geometry by the 'transfer' ...
DEFF Research Database (Denmark)
Nicholls, Stuart G.; Gwozdz, Wencke; Reisch, Lucia
2011-01-01
When it comes to buying food, price is influential, but is a ‘fat tax’ the answer to curb obesity? Dr Stuart G Nicholls from Lancaster University, Assistant Professor Dr Wencke Gwozdz and Professor, Dr Lucia A Reisch from Copenhagen Business School and Dr Kristin Voigt from Lancaster University...
DEFF Research Database (Denmark)
de Souza Reboucas, Geraldo Francisco; Santos, Ilmar; Thomsen, Jon Juel
2017-01-01
The frequency response of a single degree of freedom vibro-impact oscillator is analyzed using Harmonic Linearization, Averaging and Numeric Simulation, considering three different impact force models: one given by a piecewise-linear function (Kelvin-Voigt model), another by a high-order power...
TÜ tähistab rahvusülikooli aastapäeva
2010-01-01
Emakeelse ülikooli 91. aastapäeva tähistamisest. Aktusel promoveeriti 103 doktorit ja 5 audoktorit. Audoktoriks said: Jaan Einasto (Eesti), Vilmos Voigt (Ungari), Pekka Topias Männistö (Soome), William J. Mitsch (USA), Lars Oreland (Rootsi)
Proceedings of the 2nd Workshop on Awareness and Reflection in Technology-Enhanced Learning
Moore, Adam; Pammer, Viktoria; Pannese, Lucia; Prilla, Michael; Rajagopal, Kamakshi; Reinhardt, Wolfgang; Ullman, Thomas; Voigt, Christian
2013-01-01
Moore, A., Pammer, V., Pannese, L., Prilla, M., Rajagopal, K., Reinhardt, W., Ullman, Th. D., & Voigt, Ch. (Eds.) (2012). Proceedings of the 2nd Workshop on Awareness and Reflection in Technology Enhanced Learning. In conjunction with the 7th European Conference on Technology Enhanced Learning: 21st
Understanding the meaning of awareness in Research Networks
Reinhardt, Wolfgang; Mletzko, Christian; Sloep, Peter; Drachsler, Hendrik
2013-01-01
Reinhardt, W., Mletzko, C., Sloep, P. B., & Drachsler, H. (2012). Understanding the meaning of awareness in Research Networks. In A. Moore, V. Pammer, L. Pannese, M. Prilla, K. Rajagopal, W. Reinhardt, Th. D. Ullman, & Ch. Voigt (Eds.), Proceedings of the 2nd Workshop on Awareness and Reflection in
Fostering reflective practice with mobile technologies
Tabuenca, Bernardo; Verpoorten, Dominique; Ternier, Stefaan; Westera, Wim; Specht, Marcus
2012-01-01
Tabuenca, B., Verpoorten, D., Ternier, S., Westera, W., & Specht, M. (2012). Fostering reflective practice with mobile technologies. In A. Moore, V. Pammer, L. Pannese, M. Prilla, K. Rajagopal, W. Reinhardt, Th. D. Ullman, & Ch. Voigt (Eds.), Proceedings of the 2nd Workshop on Awareness and
In vitro antioxidant activities of the fractions of Coccinia grandis l. leaf ...
African Journals Online (AJOL)
The present study was aimed at investigating the antioxidant activities of the various fractions of the hydromethanolic extract of the leaves of Coccinia grandis L. Voigt. (Cucurbitaceae). The antioxidant activities of the fractions have been evaluated by using nine in vitro assays and were compared to standard antioxidants ...
African Journals Online (AJOL)
Dr Ahmed
Taxonomy of African Ticks: An Identification Manual. ICIPE Science Press,. Nairobi. Schein, E., Rehbein, G., Voigt, W. P & Zweygarth, E. (1981). Babesia equi (Laveran 1901). 1: Development in horses and in lymphocytes culture. Tropenmed Parasitology, 32:223-227. Urquhart, G. M., Armour, J., Duncan, J. L., Dunn, A. M &.
Indian Academy of Sciences (India)
Home; Journals; Sadhana. S SAHA. Articles written in Sadhana. Volume 42 Issue 9 September 2017 pp 1459-1471. Influence of yielding base and rigid base on propagation of Rayleigh-type wave in a viscoelastic layer of Voigt type · S SAHA A CHATTOPADHYAY K C MISTRI A K SINGH · More Details Abstract Fulltext PDF.
Directory of Open Access Journals (Sweden)
Mitsuhiro Nakao
2014-01-01
Full Text Available We prove the existence and uniqueness of a global decaying solution to the initial boundary value problem for the quasilinear wave equation with Kelvin-Voigt dissipation and a derivative nonlinearity. To derive the required estimates of the solutions we employ a 'loan' method and use a difference inequality on the energy.
Indian Academy of Sciences (India)
Home; Journals; Bulletin of Materials Science. P Chatterjee. Articles written in Bulletin of Materials Science. Volume 25 Issue 3 June 2002 pp 251-257 Experimental Techniques. Voigt modelling of size–strain analysis: Application to -Al2O3 prepared by combustion technique · K Santra P Chatterjee S P Sen Gupta.
Indian Academy of Sciences (India)
heat of ionisation, etc. The cyclic processes can be used to verify the theoretically calculated value of the lattice-energy, as well as to estimate the heats of certain chemical reactions. 1 W. Voigt, Ann. de Phy. 1907, 24, 290. 2 M. Born, Verh, d. Deutsch Phys., 1919, 21, 679. 8 F. Haber, Verh. d. Deutsch Phys., 1919, 21, 750. Al.
Indian Academy of Sciences (India)
Home; Journals; Sadhana. K C MISTRI. Articles written in Sadhana. Volume 42 Issue 9 September 2017 pp 1459-1471. Influence of yielding base and rigid base on propagation of Rayleigh-type wave in a viscoelastic layer of Voigt type · S SAHA A CHATTOPADHYAY K C MISTRI A K SINGH · More Details Abstract Fulltext ...
African Journals Online (AJOL)
In Part II, Voigt provides a clear exposition of Augustines' s Comenius and Kant's conceptualisation of peace (pp. 146-60) and recommends Comenius' notion of ... normative ethics' he shows that all other philosophies are 'subjectocentrically constructed', and as such they all 'restrict human beings from transcending their.
Superconvergent sum rules for the normal reflectivity
International Nuclear Information System (INIS)
Furuya, K.; Zimerman, A.H.; Villani, A.
1976-05-01
Families of superconvergent relations for the normal reflectivity function are written. Sum rules connecting the difference of phases of the reflectivities of two materials are also considered. Finally superconvergence relations and sum rules for magneto-reflectivity in the Faraday and Voigt regimes are also studied
Rizo, P. J.; Pugzlys, A.; Liu, J.; Reuter, D.; Wieck, A. D.; van der Wal, C. H.; van Loosdrecht, P. H. M.; Pugžlys, A.
2008-01-01
A compact cryogenic Kerr microscope for operation in the small volume of high-field magnets is described. It is suited for measurements both in Voigt and Faraday configurations. Coupled with a pulsed laser source, the microscope is used to measure the time-resolved Kerr rotation response of
Influence of yielding base and rigid base on propagation of Rayleigh ...
Indian Academy of Sciences (India)
The present study aims to study the propagation of Rayleigh-type wave in a layer, composed of isotropic viscoelastic material of Voigt type, with the effect of yielding base and rigid base in two distinct cases.With the aid of an analytical treatment, closed-form expressions of phase velocity and damped velocity for both the ...
Factorization of a class of almost linear second-order differential equations
International Nuclear Information System (INIS)
Estevez, P G; Kuru, S; Negro, J; Nieto, L M
2007-01-01
A general type of almost linear second-order differential equations, which are directly related to several interesting physical problems, is characterized. The solutions of these equations are obtained using the factorization technique, and their non-autonomous invariants are also found by means of scale transformations
Automated adaptive sliding mode control scheme for a class of real ...
Indian Academy of Sciences (India)
main goal of the present investigation is to synchronize two non-identical hyper- ... n-dimensional non-autonomous chaotic systems under linear and nonlinear ..... number of numerical simulations are now carried out through MATLAB programming language. .... In this numerical example, figures 6 to 9 illustrate the states of.
Integration by parts and by substitution unified, Green's Theorem and uniqueness for ODEs
Cid, J. A.; Pouso, Rodrigo López
2015-01-01
We present a rather unknown version of the change of variables formula for non-autonomous functions. We will show that this formula is equivalent to Green's Theorem for regions of the plane bounded by the graphs of two continuously differentiable functions. Besides, the formula has interesting applications in the uniqueness of solution of ordinary differential equations.
Geometrical and dynamical properties of Lorenz type system
International Nuclear Information System (INIS)
Klinshpont, N E; Sataev, E A; Plykin, R V
2005-01-01
A new topological invariant (Lorenz-manuscript) leading to the existence of uncountable set of topologically various attractors is proposed. A new definition of the hyperbolic properties of the Lorenz system close to singular hyperbolicity is introduced. This definition gives the opportunity to prove that small non-autonomous perturbations do not lead to the appearance of the stable solutions
Korkmaz, Erdal
2017-01-01
In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov's second method. The results obtained essentially improve, include and complement the results in the literature.
CHAOTIC DUFFING TYPE OSCILLATOR WITH INERTIAL DAMPING
DEFF Research Database (Denmark)
Tamaševicius, Arunas; Mykolaitis, Gytis; Kirvaitis, Raimundas
2009-01-01
A novel Duffing-Holmes type autonomous chaotic oscillator is described. In comparison with the well-known non-autonomous Duffing-Holmes circuit it lacks the external periodic drive, but includes two extra linear feedback sub-circuits, namely a direct positive feedback loop, and an inertial negati...... feedback loop. SPICE simulation and hardware experimental results are presented....
Directory of Open Access Journals (Sweden)
Erdal Korkmaz
2017-06-01
Full Text Available Abstract In this paper, we give sufficient conditions for the boundedness, uniform asymptotic stability and square integrability of the solutions to a certain fourth order non-autonomous differential equations with delay by using Lyapunov’s second method. The results obtained essentially improve, include and complement the results in the literature.
Reddy, P.V.; Engwerda, J.C.
2011-01-01
In this article we derive necessary and sufficient conditions for the existence of Pareto optimal solutions for infinite horizon cooperative differential games. We consider games defined by non autonomous and discounted autonomous systems. The obtained results are used to analyze the regular
Onset of chaos in a single-phase power electronic inverter
DEFF Research Database (Denmark)
Avrutin, Viktor; Mosekilde, Erik; Zhusubaliyev, Zhanybai T.
2015-01-01
derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead...
Optical bistability without the rotating wave approximation
Energy Technology Data Exchange (ETDEWEB)
Sharaby, Yasser A., E-mail: Yasser_Sharaby@hotmail.co [Physics Department, Faculty of Applied Sciences, Suez Canal University, Suez (Egypt); Joshi, Amitabh, E-mail: ajoshi@eiu.ed [Department of Physics, Eastern Illinois University, Charleston, IL 61920 (United States); Hassan, Shoukry S., E-mail: Shoukryhassan@hotmail.co [Mathematics Department, College of Science, University of Bahrain, P.O. Box 32038 (Bahrain)
2010-04-26
Optical bistability for two-level atomic system in a ring cavity is investigated outside the rotating wave approximation (RWA) using non-autonomous Maxwell-Bloch equations with Fourier decomposition up to first harmonic. The first harmonic output field component exhibits reversed or closed loop bistability simultaneously with the usual (anti-clockwise) bistability in the fundamental field component.
Optical bistability without the rotating wave approximation
International Nuclear Information System (INIS)
Sharaby, Yasser A.; Joshi, Amitabh; Hassan, Shoukry S.
2010-01-01
Optical bistability for two-level atomic system in a ring cavity is investigated outside the rotating wave approximation (RWA) using non-autonomous Maxwell-Bloch equations with Fourier decomposition up to first harmonic. The first harmonic output field component exhibits reversed or closed loop bistability simultaneously with the usual (anti-clockwise) bistability in the fundamental field component.
Pramana – Journal of Physics | Indian Academy of Sciences
Indian Academy of Sciences (India)
This paper studies the global synchronization of non-autonomous, time-delay, chaotic power systems via linear state-error feedback control. The frequency domain criterion and the LMI criterion are proposed and applied to design the coupling matrix. Some algebraic criteria via a single-variable linear coupling are derived ...
The control of an optical hyper-chaotic system
International Nuclear Information System (INIS)
Jiang Shumin; Tian Lixin; Wang Xuedi
2007-01-01
This paper discusses the problem of hyper-chaos control of an optical system. Based on Lyapunov stability theory, a non-autonomous feedback controller is designed. The proposed controller ensures that the hyper-chaotic system will be asymptotically stable. Numerical simulation of the original and the controlled system is provided to show the effectiveness of our method
Common and distinct genetic properties of ESCRT-II components in Drosophila.
Directory of Open Access Journals (Sweden)
Hans-Martin Herz
Full Text Available BACKGROUND: Genetic studies in yeast have identified class E vps genes that form the ESCRT complexes required for protein sorting at the early endosome. In Drosophila, mutations of the ESCRT-II component vps25 cause endosomal defects leading to accumulation of Notch protein and increased Notch pathway activity. These endosomal and signaling defects are thought to account for several phenotypes. Depending on the developmental context, two different types of overgrowth can be detected. Tissue predominantly mutant for vps25 displays neoplastic tumor characteristics. In contrast, vps25 mutant clones in a wild-type background trigger hyperplastic overgrowth in a non-autonomous manner. In addition, vps25 mutant clones also promote apoptotic resistance in a non-autonomous manner. PRINCIPAL FINDINGS: Here, we genetically characterize the remaining ESCRT-II components vps22 and vps36. Like vps25, mutants of vps22 and vps36 display endosomal defects, accumulate Notch protein and--when the tissue is predominantly mutant--show neoplastic tumor characteristics. However, despite these common phenotypes, they have distinct non-autonomous phenotypes. While vps22 mutations cause strong non-autonomous overgrowth, they do not affect apoptotic resistance. In contrast, vps36 mutations increase apoptotic resistance, but have little effect on non-autonomous proliferation. Further characterization reveals that although all ESCRT-II mutants accumulate Notch protein, only vps22 and vps25 mutations trigger Notch activity. CONCLUSIONS/SIGNIFICANCE: The ESCRT-II components vps22, vps25 and vps36 display common and distinct genetic properties. Our data redefine the role of Notch for hyperplastic and neoplastic overgrowth in these mutants. While Notch is required for hyperplastic growth, it appears to be dispensable for neoplastic transformation.
Study on Stress Development in the Phase Transition Layer of Thermal Barrier Coatings
Directory of Open Access Journals (Sweden)
Yijun Chai
2016-09-01
Full Text Available Stress development is one of the significant factors leading to the failure of thermal barrier coating (TBC systems. In this work, stress development in the two phase mixed zone named phase transition layer (PTL, which grows between the thermally grown oxide (TGO and the bond coat (BC, is investigated by using two different homogenization models. A constitutive equation of the PTL based on the Reuss model is proposed to study the stresses in the PTL. The stresses computed with the proposed constitutive equation are compared with those obtained with Voigt model-based equation in detail. The stresses based on the Voigt model are slightly higher than those based on the Reuss model. Finally, a further study is carried out to explore the influence of phase transition proportions on the stress difference caused by homogenization models. Results show that the stress difference becomes more evident with the increase of the PTL thickness ratio in the TGO.
New techniques for multi-level cross section calculation and fitting
International Nuclear Information System (INIS)
Froehner, F.H.
1981-01-01
A number of recent developments in multi-level cross section work are described. A new iteration scheme for the conversion of Reich-Moore resonance parameters to Kapur-Peierls parameters allows application of Turing's method for Gaussian broadening of meromorphic functions directly to multi-level cross section expressions, without recourse to the Voigt profiles psi and chi. This makes calculation of Doppler-broadened Reich-Moore and MLBW cross sections practically as fast as SLBW and Adler-Adler cross section calculations involving the Voigt profiles. A convenient distant-level treatment utilizing average resonance parameters is presented. Apart from effectively dealing with edge effects in resonance fitting work it also leads to a simple prescription for the determination of bound levels which reproduce the thermal cross sections correctly. A brief discussion of improved resonance shape fitting techniques is included, with emphasis on the importance of correlated errors and proper use of prior information by application of Bayes' theorem
Models for infrared atmospheric radiation
Tiwari, S. N.
1976-01-01
Line and band models for infrared spectral absorption are discussed. Radiative transmittance and integrated absorptance of Lorentz, Doppler, and voigt line profiles were compared for a range of parameters. It was found that, for the intermediate path lengths, the combined Lorentz-Doppler (Voigt) profile is essential in calculating the atmospheric transmittance. Narrow band model relations for absorptance were used to develop exact formulations for total absorption by four wide band models. Several continuous correlations for the absorption of a wide band model were compared with the numerical solutions of the wide band models. By employing the line-by-line and quasi-random band model formulations, computational procedures were developed for evaluating transmittance and upwelling atmospheric radiance. Homogeneous path transmittances were calculated for selected bands of CO, CO2, and N2O and compared with experimental measurements. The upwelling radiance and signal change in the wave number interval of the CO fundamental band were also calculated.
International Nuclear Information System (INIS)
Li Jingsong; Durry, Georges; Cousin, Julien; Joly, Lilian; Parvitte, Bertrand; Zeninari, Virginie
2010-01-01
The self-broadening coefficients of acetylene at room temperature have been measured for 10 lines in the P branch of the ν 1 +ν 3 (Σ u + )-0(Σ g + ) bands of 12 C 2 H 2 and 13 C 12 CH 2 near 1.533 μm, using a high resolution tunable diode laser spectrometer developed for the Martian space mission PHOBOS-Grunt. The collisional widths are obtained by fitting each recorded line with the Voigt profile as well as the Rautian profile accounting for the collisional Dicke narrowing effect. The standard Voigt model provides slightly smaller broadening coefficients than the Rautian model. Our data are thoroughly compared to the main atmospheric molecule database HITRAN and previous values in various bands of acetylene. Moreover, it is worth noting that a large number of new transitions not listed in the latest HITRAN08 were measured and identified for the first time.
Naval Special Warfare: Identifying and Prioritizing Core Attributes of the Profession
2014-12-01
sociologist named Morris Janowitz described the transition and development of American military professionalism in his book titled The Professional...Westport, CT: Praeger Publishers, 1989). 45 For a full discussion see Morris Janowitz, The Professional Soldier: A Social and Political Portrait...Sent: Tuesday , August 19, 2014 1:36 AM To: NSW Survey Distro Cc: Wisotzki, Stephen C CAPT USSOCOM NAVSOC; Voigt, Bradley D Mr CIV USSOCOM
International Nuclear Information System (INIS)
Rohmann, D.; Koehler, T.
1987-02-01
This is a description of the computer code FIT, written in FORTRAN-77 for a PDP 11/34. FIT is an interactive program to decude position, width and intensity of lines of X-ray spectra (max. length of 4K channels). The lines (max. 30 lines per fit) may have Gauss- or Voigt-profile, as well as exponential tails. Spectrum and fit can be displayed on a Tektronix terminal. (orig.) [de
Schulz AP; Lange V; Gille J; Voigt C; Fröhlich S; Stuhr M; Jürgens C
2013-01-01
Arndt P Schulz,1 Vivien Lange,2 Justus Gille,1 Christine Voigt,3 Susanne Fröhlich,4 Markus Stuhr,1 Christian Jürgens5 1Department of Orthopedics, Trauma, and Sports Medicine, University Hospital Lübeck, Lübeck, Germany; 2Department of Rehabilitation, Sana Regio Klinikum, Wedel, Germany; 3Department of Sports Medicine and Arthroscopy, Diakoniekrankenhaus Friederikenstift, Hannover, Germany; 4Department of Orthopedics, University of Rostock, Rostock, Germany;...
The Faraday effect in two-dimensional magneto-photonic crystals
International Nuclear Information System (INIS)
Merzlikin, A.M.; Vinogradov, A.P.; Inoue, M.; Khanikaev, A.B.; Granovsky, A.B.
2006-01-01
The necessary conditions for the observation of the Faraday effect in 2D magneto-photonic crystals are discussed. It is found. that the Faraday effect may be observed in the directions where any couple of the wave vectors of the harmonics consisting the Bloch waves of TE and TM solutions in zero magnetic field are identical. This direction corresponds neither to Faraday nor to Voigt geometry
The Faraday effect in two-dimensional magneto-photonic crystals
Energy Technology Data Exchange (ETDEWEB)
Merzlikin, A.M. [Institute for Theoretical and Applied Electromagnetism, OIVT, Russian Academy of Sciences, Izhorskay 13/19, Moscow 125412 (Russian Federation)]. E-mail: merzlikin_a@mail.ru; Vinogradov, A.P. [Institute for Theoretical and Applied Electromagnetism, OIVT, Russian Academy of Sciences, Izhorskay 13/19, Moscow 125412 (Russian Federation); Inoue, M. [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, 1-1, Hibari-Ga-Oka, Tempaku, Toyohashi 441-8580 (Japan); Khanikaev, A.B. [Department of Electrical and Electronic Engineering, Toyohashi University of Technology, 1-1, Hibari-Ga-Oka, Tempaku, Toyohashi 441-8580 (Japan); Granovsky, A.B. [Faculty of Physics, Lomonosov Moscow State University, Leninski Gory, Moscow 119992 (Russian Federation)
2006-05-15
The necessary conditions for the observation of the Faraday effect in 2D magneto-photonic crystals are discussed. It is found. that the Faraday effect may be observed in the directions where any couple of the wave vectors of the harmonics consisting the Bloch waves of TE and TM solutions in zero magnetic field are identical. This direction corresponds neither to Faraday nor to Voigt geometry.
Numerical Approaches to Thermally Coupled Perfect Plasticity
Czech Academy of Sciences Publication Activity Database
Bartels, S.; Roubíček, Tomáš
2013-01-01
Roč. 29, č. 6 (2013), s. 1837-1863 ISSN 0749-159X R&D Projects: GA ČR GAP201/10/0357 Institutional support: RVO:61388998 Keywords : thermodynamics * Prandtl-Reuss plasticity * Kelvin-Voigt rheology Subject RIV: BA - General Mathematics Impact factor: 1.057, year: 2013 http://onlinelibrary.wiley.com/doi/10.1002/num.21779/full
Taheri, Shahyar
2015-01-01
Accurate and efficient tire models for deformable terrain operations are essential for performing vehicle simulations. Assessment of the forces and moments that occur at the tire-terrain interface, and the effect of the tire motion on properties of the terrain are crucial in understanding the performance of a vehicle. In order to model the dynamic behavior of the tire on different terrains, a lumped mass discretized tire model using Kelvin-Voigt elements is developed. To optimize the computat...
Belt Conveyor Dynamic Characteristics and Influential Factors
Li, Junxia; Pang, Xiaoxu
2018-01-01
This paper uses the Kelvin-Voigt viscoelastic model to establish the continuous dynamic equations for tail hammer tension belt conveyors. The viscoelastic continuity equations are solved using the generalized coordinate method. We analyze various factors influencing longitudinal vibration of the belt conveyor by simulation and propose a control strategy to limit the vibration. The proposed approach and control strategy were verified by several experimental researches and cases. The proposed a...
Belt Conveyor Dynamic Characteristics and Influential Factors
Directory of Open Access Journals (Sweden)
Junxia Li
2018-01-01
Full Text Available This paper uses the Kelvin-Voigt viscoelastic model to establish the continuous dynamic equations for tail hammer tension belt conveyors. The viscoelastic continuity equations are solved using the generalized coordinate method. We analyze various factors influencing longitudinal vibration of the belt conveyor by simulation and propose a control strategy to limit the vibration. The proposed approach and control strategy were verified by several experimental researches and cases. The proposed approach provides improved accuracy for dynamic design of belt conveyors.
Nonlinearly coupled thermo-visco-elasticity
Czech Academy of Sciences Publication Activity Database
Roubíček, Tomáš
2013-01-01
Roč. 20, č. 3 (2013), s. 1243-1275 ISSN 1021-9722 R&D Projects: GA ČR GAP201/10/0357 Institutional support: RVO:61388998 Keywords : kelvin-voigt rheology * small strains * nonsimple materials Subject RIV: BA - General Mathematics Impact factor: 0.971, year: 2013 http://link.springer.com/article/10.1007%2Fs00030-012-0207-9
Amplifying Riboswitch Signal Output using Cellular Wiring
2017-01-30
included in this document for any purpose other than Government procurement does not in any way obligate the U.S. Government. The fact that the...release. 88ABW-2016-3094, 23 June 2016 ACKNOWLEDGEMENTS We thank Dr. Christopher Voigt (Massachusetts Institute of Technology) for his generous gift of...plasmids, and Dr. Dimitri Deheyn (U.C. San Diego) for his generous gift of GFPa1, and Dr. Jason Micklefield (University of Manchester, UK) for
2012-12-16
sterilizing without causing toxicity in vivo. 1 Introduction As reported to the Centers for Disease Control and Pre- vention (CDC) between 2006 and...Owings MF. National Hospital Discharge Survey. Advance Data from Vital and Health Statistics. United States: Centers for Disease Control and Prevention...10.1007/s10856-012-4730-3. 19. Shirwaiker RA, Wysk RA, Kariyawasam S, Carrion H, Voigt RC. Micro-scale fabrication and characterization of a silver–polymer
Gerbi, Sté phane; Said-Houari, Belkacem
2011-01-01
In this paper we consider a multi-dimensional wave equation with dynamic boundary conditions, related to the KelvinVoigt damping. Global existence and asymptotic stability of solutions starting in a stable set are proved. Blow up for solutions of the problem with linear dynamic boundary conditions with initial data in the unstable set is also obtained. © 2011 Elsevier Ltd. All rights reserved.
Localized magnetic polaritons in thin flims
International Nuclear Information System (INIS)
Lima, N.P.
1985-01-01
In this thesis we study the localized retarted modes (polaritons) in a ferromagnetic slab. For this we used the linear response theory to obtain the dispersion relations of the bulk, surface and guided modes, for a geometry more general than the Voigt's one. We got both the Green functions in the Voight geometry and the power spectra of these modes. Finally, we show that these Green functions fulfill the correct general symmetry requirements. (author) [pt
Gerbi, Stéphane
2011-12-01
In this paper we consider a multi-dimensional wave equation with dynamic boundary conditions, related to the KelvinVoigt damping. Global existence and asymptotic stability of solutions starting in a stable set are proved. Blow up for solutions of the problem with linear dynamic boundary conditions with initial data in the unstable set is also obtained. © 2011 Elsevier Ltd. All rights reserved.
Non-reciprocity and topology in optics: one-way road for light via surface magnon polariton.
Ochiai, Tetsuyuki
2015-02-01
We show how non-reciprocity and topology are used to construct an optical one-way waveguide in the Voigt geometry. First, we present a traditional approach of the one-way waveguide of light using surface polaritons under a static magnetic field. Second, we explain a recent discovery of a topological approach using photonic crystals with the magneto-optical coupling. Third, we present a combination of the two approaches, toward a broadband one-way waveguide in the microwave range.
Elastic constants of a Laves phase compound: C15 NbCr2
International Nuclear Information System (INIS)
Ormeci, A.; Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E.
1997-01-01
The single-crystal elastic constants of C15 NbCr 2 have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson's ratio and the direction dependence of Young's modulus
Modelling water hammer in viscoelastic pipelines: short brief
Urbanowicz, K.; Firkowski, M.; Zarzycki, Z.
2016-10-01
The model of water hammer in viscoelastic pipelines is analyzed. An appropriate mathematical model of water hammer in polymer pipelines is presented. An additional term has been added to continuity equation to describe the retarded deformation of the pipe wall. The mechanical behavior of viscoelastic material is described by generalized Kelvin-Voigt model. The comparison of numerical simulation and experimental data from well known papers is presented. Short discussion about obtained results are given.
Program for the analysis of pulse height spectra and the background from a proportional detector
International Nuclear Information System (INIS)
Flores-Llamas, H.; Yee-Madeira, H.; Contreras-Puente, G.; Zamorano-Ulloa, R.
1991-01-01
A PC-Fortran program is presented for fitting of lineshapes and the analysis of pulse height spectra obtainable with proportional detectors. The common fitting and analysis of pulse height spectra by means of mixed Gaussian lineshapes is readily improved by using Voigt lineshapes. In addition, the background can be evaluated during the fitting process without the need of extra measurements. As an application of the program, a pulse height transmission spectrum accumulated with a static 57 Co source and detected with an argon-metane proportional detector, was least squares fitted to an elaborated complex trial lineshape function containing two Voigt lines plus a straight line. The fitting straight line parameters a and b characterize quantitatively the background. The very good PC-fitting obtained shows that the fitting of experimental spectra with the more realistic Voigt lineshapes is no longer a formidable task and that it is possible to evaluate and subtract the background inherent to the experiment during the fitting process. (orig.)
Quantitative analysis of impact measurements using dynamic load cells
Directory of Open Access Journals (Sweden)
Brent J. Maranzano
2016-03-01
Full Text Available A mathematical model is used to estimate material properties from a short duration transient impact force measured by dropping spheres onto rectangular coupons fixed to a dynamic load cell. The contact stress between the dynamic load cell surface and the projectile are modeled using Hertzian contact mechanics. Due to the short impact time relative to the load cell dynamics, an additional Kelvin–Voigt element is included in the model to account for the finite response time of the piezoelectric crystal. Calculations with and without the Kelvin–Voigt element are compared to experimental data collected from combinations of polymeric spheres and polymeric and metallic surfaces. The results illustrate that the inclusion of the Kelvin–Voigt element qualitatively captures the post impact resonance and non-linear behavior of the load cell signal and quantitatively improves the estimation of the Young's elastic modulus and Poisson's ratio. Mathematically, the additional KV element couples one additional differential equation to the Hertzian spring-dashpot equation. The model can be numerically integrated in seconds using standard numerical techniques allowing for its use as a rapid technique for the estimation of material properties. Keywords: Young's modulus, Poisson's ratio, Dynamic load cell
Energy Technology Data Exchange (ETDEWEB)
Berryman, J. G.
2012-03-01
While the well-known Voigt and Reuss (VR) bounds, and the Voigt-Reuss-Hill (VRH) elastic constant estimators for random polycrystals are all straightforwardly calculated once the elastic constants of anisotropic crystals are known, the Hashin-Shtrikman (HS) bounds and related self-consistent (SC) estimators for the same constants are, by comparison, more difficult to compute. Recent work has shown how to simplify (to some extent) these harder to compute HS bounds and SC estimators. An overview and analysis of a subsampling of these results is presented here with the main point being to show whether or not this extra work (i.e., in calculating both the HS bounds and the SC estimates) does provide added value since, in particular, the VRH estimators often do not fall within the HS bounds, while the SC estimators (for good reasons) have always been found to do so. The quantitative differences between the SC and the VRH estimators in the eight cases considered are often quite small however, being on the order of ±1%. These quantitative results hold true even though these polycrystal Voigt-Reuss-Hill estimators more typically (but not always) fall outside the Hashin-Shtrikman bounds, while the self-consistent estimators always fall inside (or on the boundaries of) these same bounds.
Min, M.
2017-10-01
Context. Opacities of molecules in exoplanet atmospheres rely on increasingly detailed line-lists for these molecules. The line lists available today contain for many species up to several billions of lines. Computation of the spectral line profile created by pressure and temperature broadening, the Voigt profile, of all of these lines is becoming a computational challenge. Aims: We aim to create a method to compute the Voigt profile in a way that automatically focusses the computation time into the strongest lines, while still maintaining the continuum contribution of the high number of weaker lines. Methods: Here, we outline a statistical line sampling technique that samples the Voigt profile quickly and with high accuracy. The number of samples is adjusted to the strength of the line and the local spectral line density. This automatically provides high accuracy line shapes for strong lines or lines that are spectrally isolated. The line sampling technique automatically preserves the integrated line opacity for all lines, thereby also providing the continuum opacity created by the large number of weak lines at very low computational cost. Results: The line sampling technique is tested for accuracy when computing line spectra and correlated-k tables. Extremely fast computations ( 3.5 × 105 lines per second per core on a standard current day desktop computer) with high accuracy (≤1% almost everywhere) are obtained. A detailed recipe on how to perform the computations is given.
List of Organizing Committees and Sponsors
2012-03-01
Organizers DIRECTORS Maria L CalvoPresident of International Commission for Optics, Spain Aram V PapoyanDirector of Institute for Physical Research of NAS, Armenia HEADS OF PROJECT Tigran Dadalyan YSU, Armenia Artsrun MartirosyanIPR, Armenia COORDINATOR Narine GevorgyanIPR, Armenia / ICTP, Italy MANAGERS Paytsar MantashyanIPR, Armenia Karen VardanyanIPR, Armenia INTERNATIONAL ADVISORY COMMITTEE Marcis AuzinshLatvia Roland AvagyanArmenia Tapash ChakrabortyCanada Yuri ChilingaryanArmenia Eduard KazaryanArmenia Albert KirakosyanArmenia Radik KostanyanArmenia Avinash PandeyIndia Marat SoskinUkraine INTERNATIONAL PROGRAM COMMITTEE David Sarkisyan (Chair)Armenia Roman AlaverdyanArmenia Dan ApostolRomania Levon AslanyanArmenia Aranya BhattacherjeeIndia Gagik BuniatyanArmenia Vigen ChaltykyanArmenia Roldao Da RochaBrazil Miltcho DanailovItaly Vladimir GerdtRussia Samvel GevorgyanArmenia Gayane GrigoryanArmenia Rafik HakobyanArmenia Takayuki MiyaderaJapan Levon MouradianArmenia Atom MuradyanArmenia Simon RochesterUSA Hayk SarkisyanArmenia Aleksandr VardanyanArmenia LOCAL ORGANIZING COMMITTEE Narek AghekyanArmenia Anahit GogyanArmenia Melanya GrigoryanArmenia Armen HovhannisyanArmenia Lilit HovhannisyanArmenia Tatevik KhachatryanArmenia Astghik KuzanyanArmenia Satenik KuzanyanArmenia Vladimir LazarevRussia Lilit MantashyanArmenia Hripsime MkrtchyanArmenia Pavel MuzhikyanArmenia Wahi NarsisianArmenia Sahak OrdukhanyanArmenia Anna ReymersArmenia Narine TorosyanArmenia The Symposium was organized by YSU & NAS SPIE Armenian Student Chapter Institute for Physical Research (IPR) of National Academy of Sciences (NAS) Russian-Armenian (Slavonic) University (RAU) LT-PYRKAL cjsc Yerevan State University (YSU) Official Sponsors of the Symposium LT-PYRKAlRussian ArmenianSPIE LT-PYRKAL cjscRussian-Armenian UniversityYSU & NAS SPIE Student Chapter Further sponsors NFSATICTPSCSADevout Generation National Foundation of Science and Advanced TechnologiesThe Abdus Salam International Centre
International Nuclear Information System (INIS)
Shi-Jian, Cang; Zeng-Qiang, Chen; Wen-Juan, Wu
2009-01-01
This paper presents a non-autonomous hyper-chaotic system, which is formed by adding a periodic driving signal to a four-dimensional chaotic model extended from the Lorenz system. The resulting non-autonomous hyper-chaotic system can display any dynamic behaviour among the periodic orbits, intermittency, chaos and hyper-chaos by controlling the frequency of the periodic signal. The phenomenon has been well demonstrated by numerical simulations, bifurcation analysis and electronic circuit realization. Moreover, the system is concrete evidence for the presence of Pomeau–Manneville Type-I intermittency and crisis-induced intermittency. The emergence of a different type of intermittency is similarly subjected to the frequency of periodic forcing. By statistical analysis, power scaling laws consisting in different intermittency are obtained for the lifetime in the laminar state between burst states
Lieb-Robinson bounds for multi-commutators and applications to response theory
Bru, J -B
2017-01-01
Lieb-Robinson bounds for multi-commutators are effective mathematical tools to handle analytic aspects of infinite volume dynamics of non-relativistic quantum particles with short-range, possibly time-dependent interactions. In particular, the existence of fundamental solutions is shown for those (non-autonomous) C*-dynamical systems for which the usual conditions found in standard theories of (parabolic or hyperbolic) non-autonomous evolution equations are not given. In mathematical physics, bounds on multi-commutators of an order higher than two can be used to study linear and non-linear responses of interacting particles to external perturbations. These bounds are derived for lattice fermions, in view of applications to microscopic quantum theory of electrical conduction discussed in this book. All results also apply to quantum spin systems, with obvious modifications. In order to make the results accessible to a wide audience, in particular to students in mathematics with little Physics background, basics...
Autonomy and the akratic patient.
McKnight, C J
1993-01-01
I argue that the distinction which is current in much writing on medical ethics between autonomous and non-autonomous patients cannot cope comfortably with weak-willed (incontinent) patients. I describe a case involving a patient who refuses a blood transfusion even though he or she agrees that it would be in his or her best interests. The case is discussed in the light of the treatment of autonomy by B Brody and R Gillon. These writers appear to force us to treat an incontinent patient either as autonomous, just like a rational agent whose decisions are in accordance with his beliefs or as non-autonomous, like comatose patients or children. Though neither is entirely satisfactory I opt for describing such patients as autonomous but point out that in cases like this the principle of respect for autonomy does not give a determinate answer about how the patient ought to be treated. PMID:8308874
Optimizing the Earth-LISA 'rendezvous'
International Nuclear Information System (INIS)
De Marchi, Fabrizio; Pucacco, Giuseppe; Bassan, Massimo
2012-01-01
We present a general survey of heliocentric LISA orbits, hoping that it might help in the exercise of rescoping the mission. We try to semi-analytically optimize the orbital parameters in order to minimize the disturbances coming from the Earth-LISA interaction. In a set of numerical simulations, we include non-autonomous perturbations and provide an estimate of Doppler shift and breathing as a function of the trailing angle. (paper)
Tuning chaos in network sharing common nonlinearity
Paul Asir, M.; Jeevarekha, A.; Philominathan, P.
2016-06-01
In this paper, a novel type of network called network sharing common nonlinearity comprising both autonomous and non-autonomous oscillators have been investigated. We propose that these networks are robust for operating at desired modes i.e., chaotic or periodic by altering the v-i characteristics of common nonlinear element alone. The dynamics of these networks were examined through numerical, analytical, experimental and Multisim simulations.
Some mathematical problems in non-linear Physics
International Nuclear Information System (INIS)
1983-01-01
The main results contained in this report are the following: I) A general analysis of non-autonomous conserved densities for simple linear evolution systems. II) Partial differential systems within a wide class are converted into Lagrange an form. III) Rigorous criteria for existence of integrating factor matrices. IV) Isolation of all third-order evolution equations with high order symmetries and conservation laws. (Author) 3 refs
Some mathematical problems in non-linear Physics; Algunos problemas matematicos en fisica no-lineal
Energy Technology Data Exchange (ETDEWEB)
NONE
1983-07-01
The main results contained in this report are the following: I) A general analysis of non-autonomous conserved densities for simple linear evolution systems. II) Partial differential systems within a wide class are converted into Lagrange an form. III) Rigorous criteria for existence of integrating factor matrices. IV) Isolation of all third-order evolution equations with high order symmetries and conservation laws. (Author) 3 refs.
International Nuclear Information System (INIS)
Buldyreva, J.; Margulès, L.; Motiyenko, R.A.; Rohart, F.
2013-01-01
Relaxation parameters for K-components (K≤6) of six J→J+1 rotational transitions (J=6, 10, 17, 22, 31 and 33) of CH 3 35 Cl perturbed by O 2 are measured at room temperature with Voigt, speed-dependent Voigt and Galatry profiles in order to probe the speed-dependence effects. With respect to the previous study of CH 3 35 Cl–N 2 system [Guinet et al., J Quant Spectrosc Radiat Transfer 2012;113:1113], higher active-gas pressures are reached, providing better signal-to-noise ratios, and the exact expression of the Beer–Lambert law is introduced in the fitting procedure, leading, among other advantages, to much more realistic low-pressure results. The broadening parameters of the considered lines are also computed by a semi-classical method for various relative velocities of colliders and the powers characterizing the dependence of the collisional cross-sections on relative speeds are deduced as functions of the rotational numbers J and K. Additional calculations performed with the Maxwell–Boltzmann distribution of velocities show no significant difference with the earlier results [Buldyreva et al., Phys Chem Chem Phys 2011;13:20326] obtained within the mean thermal velocity approximation. Weighted sums of the presently measured Voigt-profile O 2 -broadening parameters and of the previously published N 2 -broadening ones are calculated to yield experimental air-broadening coefficients for spectroscopic databases. -- Highlights: • Analysis of the speed dependence of relaxation rates of CH 3 Cl lines. • Introduction of the Beer–Lambert law in analysis of line-shapes recorded by FM technique. • Comparison of Maxwell–Boltzmann averaging and mean thermal velocity calculations. • Estimation of air-induced broadening for CH 3 Cl rotational lines
International Nuclear Information System (INIS)
Barber, D.P.
2015-10-01
I extend and update earlier work, summarised in an earlier paper (D.P. Barber, M. Voigt, AIP Conference Proceedings 1149 (28)), whereby the invariant polarisation-tensor field (ITF) for deuterons in storage rings was introduced to complement the invariant spin field (ISF). Taken together, the ITF and the ISF provide a definition of the equilibrium spin density-matrix field which, in turn, offers a clean framework for describing equilibrium spin-1 ensembles in storage rings. I show how to construct the ITF by stroboscopic averaging, I give examples, I discuss adiabatic invariance and I introduce a formalism for describing the effect of noise and damping.
Intensities, broadening and narrowing parameters in the ν3 band of methane
Es-sebbar, Et-touhami; Farooq, Aamir
2014-01-01
The P-branch of methane's ν3 band is probed to carry out an extensive study of the 2905-2908cm-1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001cm-1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.
Kukushkin, A. B.; Sdvizhenskii, P. A.
2017-12-01
The results of accuracy analysis of automodel solutions for Lévy flight-based transport on a uniform background are presented. These approximate solutions have been obtained for Green’s function of the following equations: the non-stationary Biberman-Holstein equation for three-dimensional (3D) radiative transfer in plasma and gases, for various (Doppler, Lorentz, Voigt and Holtsmark) spectral line shapes, and the 1D transport equation with a simple longtailed step-length probability distribution function with various power-law exponents. The results suggest the possibility of substantial extension of the developed method of automodel solution to other fields far beyond physics.
Estimation of mechanical properties of gelatin using a microbubble under acoustic radiation force
International Nuclear Information System (INIS)
Shirota, Eriko; Ando, Keita
2015-01-01
This paper is concerned with observations of the translation of a microbubble (80 μm or 137 μm in radius) in a viscoelastic medium (3 w% gelatin), which is induced by acoustic radiation force originating from 1 MHz focused ultrasound. An optical system using a high-speed camera was designed to visualize the bubble translation and deformation. If the bubble remains its spherical shape under the sonication, the bubble translation we observed can be described by theory based on the Voigt model for linear viscoelastic solids; mechanical properties of the gelatin are calculated from measurements of the terminal displacement under the sonication. (paper)
Chaves, Eduardo W V
2013-01-01
This publication is aimed at students, teachers, and researchers of Continuum Mechanics and focused extensively on stating and developing Initial Boundary Value equations used to solve physical problems. With respect to notation, the tensorial, indicial and Voigt notations have been used indiscriminately. The book is divided into twelve chapters with the following topics: Tensors, Continuum Kinematics, Stress, The Objectivity of Tensors, The Fundamental Equations of Continuum Mechanics, An Introduction to Constitutive Equations, Linear Elasticity, Hyperelasticity, Plasticity (small and large deformations), Thermoelasticity (small and large deformations), Damage Mechanics (small and large deformations), and An Introduction to Fluids. Moreover, the text is supplemented with over 280 figures, over 100 solved problems, and 130 references.
A Benchmark Study of a Seismic Analysis Program for a Single Column of a HTGR Core
Energy Technology Data Exchange (ETDEWEB)
Kang, Ji Ho [KAERI, Daejeon (Korea, Republic of)
2016-05-15
A seismic analysis program, SAPCOR (Seismic Analysis of Prismatic HTGR Core), was developed in Korea Atomic Energy Research Institute. The program is used for the evaluation of deformed shapes and forces on the graphite blocks which using point-mass rigid bodies with Kelvin-Voigt impact models. In the previous studies, the program was verified using theoretical solutions and benchmark problems. To validate the program for more complicated problems, a free vibration analysis of a single column of a HTGR core was selected and the calculation results of the SAPCOR and a commercial FEM code, Abaqus, were compared in this study.
Non-reciprocity and topology in optics: one-way road for light via surface magnon polariton
Ochiai, Tetsuyuki
2015-01-01
We show how non-reciprocity and topology are used to construct an optical one-way waveguide in the Voigt geometry. First, we present a traditional approach of the one-way waveguide of light using surface polaritons under a static magnetic field. Second, we explain a recent discovery of a topological approach using photonic crystals with the magneto-optical coupling. Third, we present a combination of the two approaches, toward a broadband one-way waveguide in the microwave range. PMID:27877739
Classical optics in generalized Maxwell Chern-Simons theory
International Nuclear Information System (INIS)
Burgess, M.; Leinaas, J.M.; Loevvik, O.M.
1993-03-01
The authors consider the propagation of electromagnetic waves in a two-dimensional polarizable medium endowed with Chern-Simons terms. The dispersion relation (refractive index) of the waves is computed and the existence of linear birefringence and anomalous dispersion is shown. When absorption is taken into account, the classic signature of a Voigt effect is found. In the case where linearly-polarized, three-dimensional waves pass through a two-dimensional plane, it is shown that there is optical activity, and the analogue of Verdet's constant is computed. 19 refs., 2 figs
Elastic constants of a Laves phase compound: C15 NbCr{sub 2}
Energy Technology Data Exchange (ETDEWEB)
Ormeci, A. [Koc Univ., Istanbul (Turkey)]|[Los Alamos National Lab., NM (United States); Chu, F.; Wills, J.M.; Chen, S.P.; Albers, R.C.; Thoma, D.J.; Mitchell, T.E. [Los Alamos National Lab., NM (United States)
1997-04-01
The single-crystal elastic constants of C15 NbCr{sub 2} have been computed by using a first-principles, self-consistent, full-potential total energy method. From these single-crystal elastic constants the isotropic elastic moduli are calculated using the Voigt and Reuss averages. The calculated values are in fair agreement with the experimental values. The implications of the results are discussed with regards to Poisson`s ratio and the direction dependence of Young`s modulus.
Zeng, Shengda; Migórski, Stanisław
2018-03-01
In this paper a class of elliptic hemivariational inequalities involving the time-fractional order integral operator is investigated. Exploiting the Rothe method and using the surjectivity of multivalued pseudomonotone operators, a result on existence of solution to the problem is established. Then, this abstract result is applied to provide a theorem on the weak solvability of a fractional viscoelastic contact problem. The process is quasistatic and the constitutive relation is modeled with the fractional Kelvin-Voigt law. The friction and contact conditions are described by the Clarke generalized gradient of nonconvex and nonsmooth functionals. The variational formulation of this problem leads to a fractional hemivariational inequality.
Superconductivity Technology Program for electric power systems: Proceedings
Energy Technology Data Exchange (ETDEWEB)
Marriott, K.B.
1993-09-01
Twenty-seven presentations are included in viewgraph form for the wire development panel, applications development panel, and thallium workshop. Authors and affiliations are: (wire development panel) Kreoger/Christen (ORNL), Malozemoff (American Superconductor Corp.), Blaugher (National Renewable Energy Lab.), Haldar (Intermagnetics), Gray/Lanagan/Eror (ANL), Bickel/Voigt/Roth (Sandia), Tkaczyk (GE), Suenaga (BNL), Willis/Korzekwa/Maley (Los Alamos); (applications development panel) Peterson/Stewart (Los Alamos), Iwasa (BNL), Hull/Nieman (ANL), Murphy/DeGregoria (ORNL), Hazelton (Intermagnetics), Dykhuizen (Sandia); (thallium workshop) Goodrich (NIST), Blaugher (NREL), Roth (Sandia), Holstein (DuPont), Paranthaman (ORNL), and Willis (Los Alamos).
Energy Technology Data Exchange (ETDEWEB)
Sawicki, K.; Malinowski, F. K.; Gałkowski, K.; Jakubczyk, T.; Kossacki, P.; Pacuski, W.; Suffczyński, J., E-mail: Jan.Suffczynski@fuw.edu.pl [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Pasteura 5 St., PL-02-093 Warsaw (Poland)
2015-01-05
A simple, single-color method for permanent marking of the position of individual self-assembled semiconductor Quantum Dots (QDs) at cryogenic temperatures is reported. The method combines in situ photolithography with standard micro-photoluminescence spectroscopy. Its utility is proven by a systematic magnetooptical study of a single CdTe/ZnTe QD containing a Mn{sup 2+} ion, where a magnetic field of up to 10 T in two orthogonal, Faraday and Voigt, configurations is applied to the same QD. The presented approach can be applied to a wide range of solid state nanoemitters.
Energy Technology Data Exchange (ETDEWEB)
Yan, W.; Chen, Z. Y., E-mail: zychen@hust.edu.cn; Huang, D. W.; Tong, R. H.; Wang, S. Y.; Wei, Y. N.; Ma, T. K.; Zhuang, G. [State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan (China); Jin, W. [Center of Interface Dynamics for Sustainability, China Academy of Engineering Physics, Chengdu, Sichuan 610200 (China); Lee, S. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Shi, Y. J. [Department of Nuclear Engineering, Seoul National University, Seoul 08826 (Korea, Republic of)
2016-11-15
An x-ray imaging crystal spectrometer has been developed on joint Texas experimental tokamak for the measurement of electron and ion temperatures from the K{sub α} spectra of helium-like argon and its satellite lines. A two-dimensional multi-wire proportional counter has been applied to detect the spectra. The electron and ion temperatures have been obtained from the Voigt fitting with the spectra of helium-like argon ions. The profiles of electron and ion temperatures show the dependence on electron density in ohmic plasmas.
International Nuclear Information System (INIS)
Yao Qiang; Zhu Yuhong; Wang Yan
2011-01-01
Ultrasoft pseudopotential within a generalized gradient approximation was employed to study the structural stability, electronic structure, and elastic properties of ternary Co 3 (Ga,W) precipitate. The Young's and shear moduli of the polycrystals containing the Co 3 (Ga,W) precipitate were calculated using the Voigt-Reuss-Hill averaging scheme. Results show that the stable ternary Co 3 (Ga,W) compound has the L1 2 structure, and is ductile in nature. The structural stability of the Co 3 (Ga,W) compound is discussed together with the calculated electronic structure.
A dynamic unilateral contact problem with adhesion and friction in viscoelasticity
Cocou, Marius; Schryve, Mathieu; Raous, Michel
2010-08-01
The aim of this paper is to study an interaction law coupling recoverable adhesion, friction and unilateral contact between two viscoelastic bodies of Kelvin-Voigt type. A dynamic contact problem with adhesion and nonlocal friction is considered and its variational formulation is written as the coupling between an implicit variational inequality and a parabolic variational inequality describing the evolution of the intensity of adhesion. The existence and approximation of variational solutions are analysed, based on a penalty method, some abstract results and compactness properties. Finally, some numerical examples are presented.
Directory of Open Access Journals (Sweden)
Netta Shemesh
2017-08-01
Full Text Available Cell-non-autonomous signals dictate the functional state of cellular quality control systems, remodeling the ability of cells to cope with stress and maintain protein homeostasis (proteostasis. One highly regulated cell-non-autonomous switch controls proteostatic capacity in Caenorhabditis elegans adulthood. Signals from the reproductive system down-regulate cyto-protective pathways, unless countered by signals reporting on germline proliferation disruption. Here, we utilized dihomo-γ-linolenic acid (DGLA that depletes the C. elegans germline to ask when cell-non-autonomous signals from the reproductive system determine somatic proteostasis and whether such regulation is reversible. We found that diet supplementation of DGLA resulted in the maintenance of somatic proteostasis after the onset of reproduction. DGLA-dependent proteostasis remodeling was only effective if animals were exposed to DGLA during larval development. A short exposure of 16 h during the second to fourth larval stages was sufficient and required to maintain somatic proteostasis in adulthood but not to extend lifespan. The reproductive system was required for DGLA-dependent remodeling of proteostasis in adulthood, likely via DGLA-dependent disruption of germline stem cells. However, arachidonic acid (AA, a somatic regulator of this pathway that does not require the reproductive system, presented similar regulatory timing. Finally, we showed that DGLA- and AA-supplementation led to activation of the gonadal longevity pathway but presented differential regulatory timing. Proteostasis and stress response regulators, including hsf-1 and daf-16, were only activated if exposed to DGLA and AA during development, while other gonadal longevity factors did not show this regulatory timing. We propose that C. elegans determines its proteostatic fate during development and is committed to either reproduction, and thus present restricted proteostasis, or survival, and thus present robust
Polydnaviruses of Parasitic Wasps: Domestication of Viruses To Act as Gene Delivery Vectors
Directory of Open Access Journals (Sweden)
Michael R. Strand
2012-01-01
Full Text Available Symbiosis is a common phenomenon in which associated organisms can cooperate in ways that increase their ability to survive, reproduce, or utilize hostile environments. Here, we discuss polydnavirus symbionts of parasitic wasps. These viruses are novel in two ways: (1 they have become non-autonomous domesticated entities that cannot replicate outside of wasps; and (2 they function as a delivery vector of genes that ensure successful parasitism of host insects that wasps parasitize. In this review we discuss how these novelties may have arisen, which genes are potentially involved, and what the consequences have been for genome evolution.
Bäcklund transformations and Hamiltonian flows
International Nuclear Information System (INIS)
Zullo, Federico
2013-01-01
In this work we show that, under certain conditions, parametric Bäcklund transformations for a finite dimensional integrable system can be interpreted as solutions to the equations of motion defined by an associated non-autonomous Hamiltonian. The two systems share the same constants of motion. This observation leads to the identification of the Hamiltonian interpolating the iteration of the discrete map defined by the transformations, which indeed in numerical applications can be considered a linear combination of the integrals appearing in the spectral curve of the Lax matrix. An example with the periodic Toda lattice is given. (paper)
Plykin type attractor in electronic device simulated in MULTISIM
Kuznetsov, Sergey P.
2011-12-01
An electronic device is suggested representing a non-autonomous dynamical system with hyperbolic chaotic attractor of Plykin type in the stroboscopic map, and the results of its simulation with software package NI MULTISIM are considered in comparison with numerical integration of the underlying differential equations. A main practical advantage of electronic devices of this kind is their structural stability that means insensitivity of the chaotic dynamics in respect to variations of functions and parameters of elements constituting the system as well as to interferences and noises.
Lagrangian-Hamiltonian unified formalism for autonomous higher order dynamical systems
International Nuclear Information System (INIS)
Prieto-Martinez, Pedro Daniel; Roman-Roy, Narciso
2011-01-01
The Lagrangian-Hamiltonian unified formalism of Skinner and Rusk was originally stated for autonomous dynamical systems in classical mechanics. It has been generalized for non-autonomous first-order mechanical systems, as well as for first-order and higher order field theories. However, a complete generalization to higher order mechanical systems is yet to be described. In this work, after reviewing the natural geometrical setting and the Lagrangian and Hamiltonian formalisms for higher order autonomous mechanical systems, we develop a complete generalization of the Lagrangian-Hamiltonian unified formalism for these kinds of systems, and we use it to analyze some physical models from this new point of view. (paper)
Variational principles and symmetries on fibered multisymplectic manifolds
Directory of Open Access Journals (Sweden)
Gaset Jordi
2016-12-01
Full Text Available The standard techniques of variational calculus are geometrically stated in the ambient of fiber bundles endowed with a (premulti-symplectic structure. Then, for the corresponding variational equations, conserved quantities (or, what is equivalent, conservation laws, symmetries, Cartan (Noether symmetries, gauge symmetries and different versions of Noether's theorem are studied in this ambient. In this way, this constitutes a general geometric framework for all these topics that includes, as special cases, first and higher order field theories and (non-autonomous mechanics.
Using impulses to control the convergence toward invariant surfaces of continuous dynamical systems
International Nuclear Information System (INIS)
Marão, José; Liu Xinzhi; Figueiredo, Annibal
2012-01-01
Let us consider a smooth invariant surface S of a given ordinary differential equations system. In this work we develop an impulsive control method in order to assure that the trajectories of the controlled system converge toward the surface S. The method approach is based on a property of a certain class of invariant surfaces whose the dynamics associated to their transverse directions can be described by a non-autonomous linear system. This fact allows to define an impulsive system which drives the trajectories toward the surface S. Also, we set up a definition of local stability exponents which can be associated to such kind of invariant surface.
Uniform persistence and upper Lyapunov exponents for monotone skew-product semiflows
International Nuclear Information System (INIS)
Novo, Sylvia; Obaya, Rafael; Sanz, Ana M
2013-01-01
Several results of uniform persistence above and below a minimal set of an abstract monotone skew-product semiflow are obtained. When the minimal set has a continuous separation the results are given in terms of the principal spectrum. In the case that the semiflow is generated by the solutions of a family of non-autonomous differential equations of ordinary, delay or parabolic type, the former results are strongly improved. A method of calculus of the upper Lyapunov exponent of the minimal set is also determined. (paper)
Feedback control and adaptive control of the energy resource chaotic system
International Nuclear Information System (INIS)
Sun Mei; Tian Lixin; Jiang Shumin; Xu Jun
2007-01-01
In this paper, the problem of control for the energy resource chaotic system is considered. Two different method of control, feedback control (include linear feedback control, non-autonomous feedback control) and adaptive control methods are used to suppress chaos to unstable equilibrium or unstable periodic orbits. The Routh-Hurwitz criteria and Lyapunov direct method are used to study the conditions of the asymptotic stability of the steady states of the controlled system. The designed adaptive controller is robust with respect to certain class of disturbances in the energy resource chaotic system. Numerical simulations are presented to show these results
International Nuclear Information System (INIS)
Liang Jinling; Cao Jinde
2003-01-01
In this Letter, the problems of boundedness and stability for a general class of non-autonomous recurrent neural networks with variable coefficients and time-varying delays are analyzed via employing Young inequality technique and Lyapunov method. Some simple sufficient conditions are given for boundedness and stability of the solutions for the recurrent neural networks. These results generalize and improve the previous works, and they are easy to check and apply in practice. Two illustrative examples and their numerical simulations are also given to demonstrate the effectiveness of the proposed results
Approximating a retarded-advanced differential equation that models human phonation
Teodoro, M. Filomena
2017-11-01
In [1, 2, 3] we have got the numerical solution of a linear mixed type functional differential equation (MTFDE) introduced initially in [4], considering the autonomous and non-autonomous case by collocation, least squares and finite element methods considering B-splines basis set. The present work introduces a numerical scheme using least squares method (LSM) and Gaussian basis functions to solve numerically a nonlinear mixed type equation with symmetric delay and advance which models human phonation. The preliminary results are promising. We obtain an accuracy comparable with the previous results.
A Completeness Study on Certain 2×2 Lax Pairs Including Zero Terms
Directory of Open Access Journals (Sweden)
Mike C. Hay
2011-09-01
Full Text Available We expand the completeness study instigated in [J. Math. Phys. 50 (2009, 103516, 29 pages] which found all 2×2 Lax pairs with non-zero, separable terms in each entry of each Lax matrix, along with the most general nonlinear systems that can be associated with them. Here we allow some of the terms within the Lax matrices to be zero. We cover all possible Lax pairs of this type and find a new third order equation that can be reduced to special cases of the non-autonomous lattice KdV and lattice modified KdV equations among others.
Lie families: theory and applications
International Nuclear Information System (INIS)
Carinena, Jose F; Grabowski, Janusz; De Lucas, Javier
2010-01-01
We analyze the families of non-autonomous systems of first-order ordinary differential equations admitting a common time-dependent superposition rule, i.e. a time-dependent map expressing any solution of each of these systems in terms of a generic set of particular solutions of the system and some constants. We next study the relations of these families, called Lie families, with the theory of Lie and quasi-Lie systems and apply our theory to provide common time-dependent superposition rules for certain Lie families.
Onset of chaos in a single-phase power electronic inverter
Energy Technology Data Exchange (ETDEWEB)
Avrutin, Viktor, E-mail: Avrutin.Viktor@ist.uni-stuttgart.de [Institute for Systems Theory and Automatic Control, University of Stuttgart, Pfaffenwaldring 9, 70550 Stuttgart (Germany); Department of Economics, Society and Politics, University of Urbino, via Saffi 42, 61029 Urbino (Italy); Mosekilde, Erik, E-mail: Erik.Mosekilde@fysik.dtu.dk [Department of Physics, The Technical University of Denmark, Fysikvej 309, 2800 Lyngby (Denmark); Zhusubaliyev, Zhanybai T., E-mail: Zhanybai@hotmail.com [Department of Computer Science, Southwest State University, 50 Years of October Str., 94, 305040 Kursk (Russian Federation); Gardini, Laura, E-mail: Laura.Gardini@uniurb.it [Department of Economics, Society and Politics, University of Urbino, via Saffi 42, 61029 Urbino (Italy)
2015-04-15
Supported by experiments on a power electronic DC/AC converter, this paper considers an unusual transition from the domain of stable periodic dynamics (corresponding to the desired mode of operation) to chaotic dynamics. The behavior of the converter is studied by means of a 1D stroboscopic map derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead to bifurcations while others do not.
International Nuclear Information System (INIS)
Yamapi, R.; Moukam Kakmeni, F.M.; Aziz-Alaoui, M.A.
2005-07-01
We consider in this paper the dynamics of the self-sustained electromechanical system with multiple functions, consisting of an electrical Rayleigh-Duffing oscillator, magnetically coupled with linear mechanical oscillators. The averaging and the balance harmonic method are used to and the amplitudes of the oscillatory states respectively in the autonomous and non-autonomous cases, and analyze the condition in which the quenching of self-sustained oscillations appears. The effects of the number of linear mechanical oscillators on the behavior of the model are discussed. Various bifurcation structures, the stability chart and the variation of the Lyapunov exponent are obtained, using numerical simulations of the equations of motion. (author)
Onset of chaos in a single-phase power electronic inverter.
Avrutin, Viktor; Mosekilde, Erik; Zhusubaliyev, Zhanybai T; Gardini, Laura
2015-04-01
Supported by experiments on a power electronic DC/AC converter, this paper considers an unusual transition from the domain of stable periodic dynamics (corresponding to the desired mode of operation) to chaotic dynamics. The behavior of the converter is studied by means of a 1D stroboscopic map derived from a non-autonomous ordinary differential equation with discontinuous right-hand side. By construction, this stroboscopic map has a high number of border points. It is shown that the onset of chaos occurs stepwise, via irregular cascades of different border collisions, some of which lead to bifurcations while others do not.
Directory of Open Access Journals (Sweden)
Ana-Marina Tomescu
2013-11-01
Full Text Available Nous allons étudier la négation dans les proverbes français et roumains dans deux situations : celle où la négation est exprimée par un système corrélatif à deux unités (ne … pas/plus, jamais, etc., considéré la règle générale en français moderne, et celle où la négation est réduite à un seul outil, autonome (non ou non autonome (ne.
The VLab repository of thermodynamics and thermoelastic properties of minerals
Da Silveira, P. R.; Sarkar, K.; Wentzcovitch, R. M.; Shukla, G.; Lindemann, W.; Wu, Z.
2015-12-01
Thermodynamics and thermoelastic properties of minerals at planetary interior conditions are essential as input for geodynamics simulations and for interpretation of seismic tomography models. Precise experimental determination of these properties at such extreme conditions is very challenging. Therefore, ab initio calculations play an essential role in this context, but at the cost of great computational effort and memory use. Setting up a widely accessible and versatile mineral physics database can relax unnecessary repetition of such computationally intensive calculations. Access to such data facilitates transactional interaction across fields and can advance more quickly insights about deep Earth processes. Hosted by the Minnesota Supercomputing Institute, the Virtual Laboratory for Earth and Planetary Materials (VLab) was designed to develop and promote the theory of planetary materials using distributed, high-throughput quantum calculations. VLab hosts an interactive database of thermodynamics and thermoelastic properties or minerals computed by ab initio. Such properties can be obtained according to user's preference. The database is accompanied by interactive visualization tools, allowing users to repeat and build upon previously published results. Using VLab2015, we have evaluated thermoelastic properties, such as elastic coefficients (Cij), Voigt, Reuss, and Voigt-Reuss-Hill aggregate averages for bulk (K) and shear modulus (G), shear wave velocity (VS), longitudinal wave velocity (Vp), and bulk sound velocity (V0) for several important minerals. Developed web services are general and can be used for crystals of any symmetry. Results can be tabulated, plotted, or downloaded from the VLab website according to user's preference.
Homogenization models for 2-D grid structures
Banks, H. T.; Cioranescu, D.; Rebnord, D. A.
1992-01-01
In the past several years, we have pursued efforts related to the development of accurate models for the dynamics of flexible structures made of composite materials. Rather than viewing periodicity and sparseness as obstacles to be overcome, we exploit them to our advantage. We consider a variational problem on a domain that has large, periodically distributed holes. Using homogenization techniques we show that the solution to this problem is in some topology 'close' to the solution of a similar problem that holds on a much simpler domain. We study the behavior of the solution of the variational problem as the holes increase in number, but decrease in size in such a way that the total amount of material remains constant. The result is an equation that is in general more complex, but with a domain that is simply connected rather than perforated. We study the limit of the solution as the amount of material goes to zero. This second limit will, in most cases, retrieve much of the simplicity that was lost in the first limit without sacrificing the simplicity of the domain. Finally, we show that these results can be applied to the case of a vibrating Love-Kirchhoff plate with Kelvin-Voigt damping. We rely heavily on earlier results of (Du), (CS) for the static, undamped Love-Kirchhoff equation. Our efforts here result in a modification of those results to include both time dependence and Kelvin-Voigt damping.
Amador, Carolina; Urban, Matthew W; Chen, Shigao; Greenleaf, James F
2012-03-07
Elasticity imaging methods have been used to study tissue mechanical properties and have demonstrated that tissue elasticity changes with disease state. In current shear wave elasticity imaging methods typically only shear wave speed is measured and rheological models, e.g. Kelvin-Voigt, Maxwell and Standard Linear Solid, are used to solve for tissue mechanical properties such as the shear viscoelastic complex modulus. This paper presents a method to quantify viscoelastic material properties in a model-independent way by estimating the complex shear elastic modulus over a wide frequency range using time-dependent creep response induced by acoustic radiation force. This radiation force induced creep method uses a conversion formula that is the analytic solution of a constitutive equation. The proposed method in combination with shearwave dispersion ultrasound vibrometry is used to measure the complex modulus so that knowledge of the applied radiation force magnitude is not necessary. The conversion formula is shown to be sensitive to sampling frequency and the first reliable measure in time according to numerical simulations using the Kelvin-Voigt model creep strain and compliance. Representative model-free shear complex moduli from homogeneous tissue mimicking phantoms and one excised swine kidney were obtained. This work proposes a novel model-free ultrasound-based elasticity method that does not require a rheological model with associated fitting requirements.
NdFeO3 nanocrystals under glycine nitrate combustion formation
Tugova, Ekaterina; Yastrebov, Sergey; Karpov, Oleg; Smith, Roger
2017-06-01
Nanocrystalline perovskite NdFeO3 with the orthorhombic structure was prepared by a glycine nitrate combustion method under different technological conditions. The starting materials Fe(NO3)3 · 9H2O,Nd(NO3)3 · 6H2O in stoichiometric amounts and H2NCH2COOH were used. These quantities were varied by changing the ratio of glycine moles to metal nitrate moles (G/N) in the range between 0.25 and 0.75. The prepared NdFeO3 nanocrystals were characterised by X-ray diffraction (XRD) and electron microscopy. Decomposition of the XRD diffraction profile using Voigt contours was exploited for analysis of the pattern in the area where the most prominent diffraction peak was situated. We demonstrate that Voigt functions reduce to Lorentzians for G / N = 0.75 and 0.55 . A volume-weighted diameter distribution function was derived using the width of the Lorentzians. The log-normal shape of the distribution is discussed in terms of the model, assuming exponential growth of cluster size in the time available for the NdFeO3 nanograin to grow.
Dynamics of magnetic nanoparticles in viscoelastic media
Energy Technology Data Exchange (ETDEWEB)
Remmer, Hilke, E-mail: h.remmer@tu-bs.de [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, Braunschweig (Germany); Roeben, Eric; Schmidt, Annette M. [Institute of Physical Chemistry, Universität zu Köln, Köln (Germany); Schilling, Meinhard; Ludwig, Frank [Institute of Electrical Measurement and Fundamental Electrical Engineering, TU Braunschweig, Braunschweig (Germany)
2017-04-01
We compare different models for the description of the complex susceptibility of magnetic nanoparticles in an aqueous gelatin solution representing a model system for a Voigt-Kelvin scheme. The analysis of susceptibility spectra with the numerical model by Raikher et al. is compared with the analysis applying a phenomenological, modified Debye model. The fit of the models to the measured data allows one to extract the viscoelastic parameter dynamic viscosity η and shear modulus G. The experimental data were recorded on single-core thermally blocked CoFe{sub 2}O{sub 4} nanoparticles in an aqueous solution with 2.5 wt% gelatin. Whereas the dynamic viscosities obtained by fitting the model – extended by distributions of hydrodynamic diameters and viscosities – agree very well, the derived values for the shear modulus show the same temporal behavior during the gelation process, but vary approximately by a factor of two. To verify the values for viscosity and shear modulus obtained from nanorheology, macrorheological measurements are in progress. - Highlights: • Ac susceptibility spectra of CoFe2O4 nanoparticles in aqueous gelatin solution. • Analysis of spectra with different approaches of Voigt-Kelvin model. • Comparison of modified Debye model with numerical model. • Both models provide similar values for viscoelastic parameters.
Line shape and ray trace calculations in saturated X-ray lasers: Application to Ni-like silver
International Nuclear Information System (INIS)
Benredjem, D.; Guilbaud, O.; Moeller, C.; Klisnick, A.; Ros, D.; Dubau, J.; Calisti, A.; Talin, B.
2006-01-01
Longitudinal coherence length in X-ray lasers depends strongly on the shape of the amplified line. We have modelled an experiment performed at the LULI facility of Ecole Polytechnique. The experiment was devoted to the study of the temporal (longitudinal) coherence of the transient Ni-like silver 4d-4p transition X-ray laser at 13.9 nm. Accurate line shape calculations using PPP, a spectral line shape code, confirm that the Voigt profile is a good approximation for this X-ray laser line. This allows us to extensively use the Voigt shape in conditions where the amplifier, i.e. the plasma produced by the interaction of a high intensity laser with a slab target, is neither stationary nor homogeneous. Our calculations involve a ray trace code which is a post-processor to the hydrodynamic simulation EHYBRID. As the effect of saturation is important for the level populations and gains we include the interaction between the amplified beam and the medium using the Maxwell-Bloch formalism. While the FWHM of the spontaneous emission profile is ∼10 mA, the amplified X-ray line exhibits gain narrowing leading to the smaller width ∼3 mA. Comparison with experiment is discussed
Energy Technology Data Exchange (ETDEWEB)
Araujo, Jorge C. de [Universidade do Estado do Rio de Janeiro (UERJ), RJ (Brazil). Dept. de Matematica], e-mail: jcaraujo@iprj.uerj.br; Moreira, Elizabeth L.; Moraes, Valeria Conde Alves [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)], e-mail: beth@cbpf.br, e-mail: conde@cbpf.br; Moreira, Ana Paula D. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Inst. de Quimica. Dept. de Quimica Analitica], e-mail: duarteap@gmail.com
2008-10-15
The crystal structure of the synthetic hydroxyapatite with 12.8 ({+-} 0,64) wt. % CO{sub 3}{sup 2-} ion content was analyzed by X-ray diffraction using the Rietveld refinement method employing Pearson VII and pseudo-Voigt functions to fit the X-ray profile. The results obtained for unit cell parameters when compared to pattern hydroxyapatite showed a decrease in the a (=b) parameter and an increase in the c parameter without significant difference between the functions employed. The separation of the anisotropic broadening of reflections originated from unit cell strains indicated that this effect is dominant in reflection line broadening, principally to hkl plans with an interatomic distance lower than 2,24 angstrom. Modifications in the atomic coordinates of C atom were noted mainly in PO{sub 4}{sup 3-} (B site) and OH{sup -} (A site) sites. The average crystallite size in the crystallography axis directions (002 and 300) suggests equi axial morphology. The results obtained to CO{sub 3}{sup 2}- content were 11.72 ({+-} 0,64) wt. % to Pearson VII and 13.20 ({+-} 0,64) wt. % to pseudo-Voigt function. The refinement of the occupancy factors to C atoms in both sites PO{sub 4}{sup 3-}(B) and OH{sup -} (A) indicated higher insertion in phosphate site than hydroxide site. However, the relative occupancy of the C atom observed in the B site is lower than in the A site. (author)
New techniques for multi-level cross section calculation and fitting
International Nuclear Information System (INIS)
Froehner, F.H.
1980-09-01
A number of recent developments in multi-level cross section work are described. A new iteration scheme for the conversion of Reich-Moore resonance parameters to Kapur-Peierls parameters allows application of Turing's method for Gaussian broadening of meromorphic functions directly to multi-level cross section expressions, without recourse to the Voigt profiles psi and chi. This makes calculation of Doppler-broadened Reich-Moore and MLBW cross sections practically as fast as SLBW and Adler-Adler cross section calculations involving the Voigt profiles. A convenient distant-level treatment utilizing average resonance parameters is presented. Apart from effectively dealing with edge effects in resonance fitting work it also leads to a simple prescription for the determination of bound levels which reproduce the thermal cross sections correctly. A brief discussion of improved resonance shape fitting techniques is included, with empahsis on the importance of correlated errors and proper use of prior information by application of Bayes' theorem. (orig.) [de
International Nuclear Information System (INIS)
Dulov, E.N.; Khripunov, D.M.
2008-01-01
It is the usual situation in spectroscopy that a continuous physical quantity, which plays the role of a spectral function argument (i.e. the abscissa of a spectrum), is sampled electronically as discrete point clouds or channels. Each channel corresponds to the midpoint of a small interval of the continuous argument. The experimentally registered value of intensity in the channel describes the averaged spectral intensity in this interval. However, an approximation of spectra by a continuous theoretical model function often assumes that the interval is small enough, and tabulation of the theoretical model function may be used without appreciable disadvantages for the fitting results. At this point, a new type of approximation error appears, such as the error of midpoint approximation to a definite integral in the rectangle method of numeric integration. This paper aims at quantitative estimation of this error in the cases of a pure Lorentz lineshape and a generalized Voigt contour. It is shown that discrete representation of continuous spectral data leads to some non-physical broadening in comparison with the tabulated model function. As a first approximation it is normal broadening. We show that even in the case of a Lorentz true lineshape we must use the tabulated Voigt function measured in channels fixed Gauss linewidth rather than a tabulated Lorentzian. Application of the results of this paper is demonstrated on Moessbauer spectra
Impact of the rail-pad multi-discrete model upon the prediction of the rail response
Mazilu, T.; Leu, M.
2017-08-01
Wheel/rail vibration has many technical effects such as wear of the rolling surfaces, rolling noise, settlement of the ballast and subgrade etc. This vibration is depending on the rail pad characteristic and subsequently, it is important to have an accurate overview on the relation between the rail pad characteristic and the level of the wheel/rail vibration. To this end, much theoretical and experimental research has been developed in the past, and for the theoretical approach the track model, in general, and, particularly, the rail pad model is of crucial importance. Usually, the rail pad model is discrete model one, neglecting the length of the rail pad. This fact is questionable because the sleepers span is only 4 times the rail pad length. Using the rail pad discrete model, the rail response is overestimated when the frequency of the excitation equals the pinned-pinned resonance frequency. In this paper, a multi-discrete model for the rail pad, consisting in many Kelvin-Voigt parallel systems, is inserted into an analytical model of the track. The track model is reduced to a rail taken as infinite Timoshenko beam, discretely supported via rail pad, sleeper and ballast. The influence of the number of Kelvin-Voigt systems of the rail pad model on the rail response is analysed.
Calculation of Debye-Scherrer diffraction patterns from highly stressed polycrystalline materials
Energy Technology Data Exchange (ETDEWEB)
MacDonald, M. J., E-mail: macdonm@umich.edu [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Vorberger, J. [Helmholtz Zentrum Dresden-Rossendorf, 01328 Dresden (Germany); Gamboa, E. J.; Glenzer, S. H.; Fletcher, L. B. [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Drake, R. P. [Climate and Space Sciences and Engineering, Applied Physics, and Physics, University of Michigan, Ann Arbor, Michigan 48109 (United States)
2016-06-07
Calculations of Debye-Scherrer diffraction patterns from polycrystalline materials have typically been done in the limit of small deviatoric stresses. Although these methods are well suited for experiments conducted near hydrostatic conditions, more robust models are required to diagnose the large strain anisotropies present in dynamic compression experiments. A method to predict Debye-Scherrer diffraction patterns for arbitrary strains has been presented in the Voigt (iso-strain) limit [Higginbotham, J. Appl. Phys. 115, 174906 (2014)]. Here, we present a method to calculate Debye-Scherrer diffraction patterns from highly stressed polycrystalline samples in the Reuss (iso-stress) limit. This analysis uses elastic constants to calculate lattice strains for all initial crystallite orientations, enabling elastic anisotropy and sample texture effects to be modeled directly. The effects of probing geometry, deviatoric stresses, and sample texture are demonstrated and compared to Voigt limit predictions. An example of shock-compressed polycrystalline diamond is presented to illustrate how this model can be applied and demonstrates the importance of including material strength when interpreting diffraction in dynamic compression experiments.
International Nuclear Information System (INIS)
Thore, A.; Dahlqvist, M.; Alling, B.; Rosén, J.
2014-01-01
In this paper, we report the by first-principles predicted properties of the recently discovered magnetic MAX phase Mn 2 GaC. The electronic band structure and vibrational dispersion relation, as well as the electronic and vibrational density of states, have been calculated. The band structure close to the Fermi level indicates anisotropy with respect to electrical conductivity, while the distribution of the electronic and vibrational states for both Mn and Ga depend on the chosen relative orientation of the Mn spins across the Ga sheets in the Mn–Ga–Mn trilayers. In addition, the elastic properties have been calculated, and from the five elastic constants, the Voigt bulk modulus is determined to be 157 GPa, the Voigt shear modulus 93 GPa, and the Young's modulus 233 GPa. Furthermore, Mn 2 GaC is found relatively elastically isotropic, with a compression anisotropy factor of 0.97, and shear anisotropy factors of 0.9 and 1, respectively. The Poisson's ratio is 0.25. Evaluated elastic properties are compared to theoretical and experimental results for M 2 AC phases where M = Ti, V, Cr, Zr, Nb, Ta, and A = Al, S, Ge, In, Sn.
Identification and evolutionary dynamics of cacta DNA transposons in brassica
International Nuclear Information System (INIS)
Nouroz, F.; Noreen, S.; Harrison, J.S.H.
2017-01-01
Transposable elements are the major drivers of genome evolution and plasticity. Due to their transposition mode, they are classified into two major classes as Retrotransposons and DNA transposons. The En/Spm or CACTA elements are diverse group of DNA transposons proliferating in plant genomes. Various bioinformatics and molecular approaches were used for identification and distribution of CACTA transposons in Brassica genome. A combination of dot plot analysis and BLASTN searches yielded 35 autonomous and 7 non-autonomous CACTA elements in Brassica. The elements ranged in sizes from 1.2 kb non-autonomous elements to 11kb autonomous elements, terminated by 3 bp Target Site Duplication (TSD) and ~15 bp conserved Terminal Inverted Repeat (TIR) motifs (5'-CACTACAAGAAAACA-3'), with heterogeneous internal regions. The transposase (TNP) was identified from autonomous CACTA elements, while other protein domains from Brassica and other plants CACTA revealed similar organizations with minor differences. Both transposases (TNPD, TNPA) are present in most CACTA, while a few CACTA harboured an additional ATHILA ORF1-like domain. The PCR analysis amplified the CACTA transposases from 40 Brassica accessions (A, B, and C-genome) suggesting their distribution among various Brassica crops. A detailed characterization and evolutionary analysis of the identified CACTA elements allowed some to be placed in genome-specific groups, while most of them (Brassica-Arabidopsis elements) have followed the same evolutionary line. The distribution of CACTA in Brassica concluded that 3 bp TSDs generating CACTA transposons contributed significantly to genome size and evolution of Brassica genome. (author)
Global nonexistence results for a class of hyperbolic systems
Said-Houari, Belkacem
2011-12-01
Our concern in this paper is to prove blow-up results to the non-autonomous nonlinear system of wave equations utt-Δu=a(t,x)| v|p,vtt-Δv=b(t,x)|u|q,t>0, x∈RN in any space dimension. We show that a curve F̃(p,q)=0 depending on the space dimension, on the exponents p,q and on the behavior of the functions a(t,x) and b(t,x) exists, such that all nontrivial solutions to the above system blow-up in a finite time whenever F̃(p,q)>0. Our method of proof uses some estimates developed by Galaktionov and Pohozaev in [11] for a single non-autonomous wave equation enabling us to obtain a system of ordinary differential inequalities from which the desired result is derived. Our result generalizes some important results such as the ones in Del Santo et al. (1996) [12] and Galaktionov and Pohozaev (2003) [11]. The advantage here is that our result applies to a wide variety of problems. © 2011 Elsevier Ltd. All rights reserved.
Forced phase-locked response of a nonlinear system with time delay after Hopf bifurcation
International Nuclear Information System (INIS)
Ji, J.C.; Hansen, Colin H.
2005-01-01
The trivial equilibrium of a nonlinear autonomous system with time delay may become unstable via a Hopf bifurcation of multiplicity two, as the time delay reaches a critical value. This loss of stability of the equilibrium is associated with two coincident pairs of complex conjugate eigenvalues crossing the imaginary axis. The resultant dynamic behaviour of the corresponding nonlinear non-autonomous system in the neighbourhood of the Hopf bifurcation is investigated based on the reduction of the infinite-dimensional problem to a four-dimensional centre manifold. As a result of the interaction between the Hopf bifurcating periodic solutions and the external periodic excitation, a primary resonance can occur in the forced response of the system when the forcing frequency is close to the Hopf bifurcating periodic frequency. The method of multiple scales is used to obtain four first-order ordinary differential equations that determine the amplitudes and phases of the phase-locked periodic solutions. The first-order approximations of the periodic solutions are found to be in excellent agreement with those obtained by direct numerical integration of the delay-differential equation. It is also found that the steady state solutions of the nonlinear non-autonomous system may lose their stability via either a pitchfork or Hopf bifurcation. It is shown that the primary resonance response may exhibit symmetric and asymmetric phase-locked periodic motions, quasi-periodic motions, chaotic motions, and coexistence of two stable motions
A Spectral Approach for Quenched Limit Theorems for Random Expanding Dynamical Systems
Dragičević, D.; Froyland, G.; González-Tokman, C.; Vaienti, S.
2018-01-01
We prove quenched versions of (i) a large deviations principle (LDP), (ii) a central limit theorem (CLT), and (iii) a local central limit theorem for non-autonomous dynamical systems. A key advance is the extension of the spectral method, commonly used in limit laws for deterministic maps, to the general random setting. We achieve this via multiplicative ergodic theory and the development of a general framework to control the regularity of Lyapunov exponents of twisted transfer operator cocycles with respect to a twist parameter. While some versions of the LDP and CLT have previously been proved with other techniques, the local central limit theorem is, to our knowledge, a completely new result, and one that demonstrates the strength of our method. Applications include non-autonomous (piecewise) expanding maps, defined by random compositions of the form {T_{σ^{n-1} ω} circ\\cdotscirc T_{σω}circ T_ω} . An important aspect of our results is that we only assume ergodicity and invertibility of the random driving {σ:Ω\\toΩ} ; in particular no expansivity or mixing properties are required.
Are bans on kidney sales unjustifiably paternalistic?
Malmqvist, Erik
2014-03-01
This paper challenges the view that bans on kidney sales are unjustifiably paternalistic, that is, that they unduly deny people the freedom to make decisions about their own bodies in order to protect them from harm. I argue that not even principled anti-paternalists need to reject such bans. This is because their rationale is not hard paternalism, which anti-paternalists repudiate, but soft paternalism, which they in principle accept. More precisely, I suggest that their rationale is what Franklin Miller and Alan Wertheimer call 'group soft paternalism'. Group soft paternalistic policies restrict the freedom of autonomous individuals, not for their own good (hard paternalism), but as an unavoidable consequence of seeking to protect other, non-autonomous individuals from harms that they have not voluntarily chosen (soft paternalism). Group soft paternalism supports prohibiting kidney sales on three conditions: (1) that such sales are potentially harmful to vendors, (2) that many vendors would suffer impaired autonomy, and (3) that distinguishing between autonomous and non-autonomous vendors and interfering only with the latter is unfeasible. I provide reasons for thinking that these conditions will often hold. © 2012 John Wiley & Sons Ltd.
Shokeen, V.; Sanchez Piaia, M.; Bigot, J.-Y.; Müller, T.; Elliott, P.; Dewhurst, J. K.; Sharma, S.; Gross, E. K. U.
2017-09-01
A joint theoretical and experimental investigation is performed to understand the underlying physics of laser-induced demagnetization in Ni and Co films with varying thicknesses excited by 10 fs optical pulses. Experimentally, the dynamics of spins is studied by determining the time-dependent amplitude of the Voigt vector, retrieved from a full set of magnetic and nonmagnetic quantities performed on both sides of films, with absolute time reference. Theoretically, ab initio calculations are performed using time-dependent density functional theory. Overall, we demonstrate that spin-orbit induced spin flips are the most significant contributors with superdiffusive spin transport, which assumes only that the transport of majority spins without spin flips induced by scattering does not apply in Ni. In Co it plays a significant role during the first ˜20 fs only. Our study highlights the material dependent nature of the demagnetization during the process of thermalization of nonequilibrium spins.
Davoyan, Arthur R; Engheta, Nader
2013-12-20
We study propagation of transverse-magnetic electromagnetic waves in the bulk and at the surface of a magnetized epsilon-near-zero (ENZ) medium in a Voigt configuration. We reveal that in a certain range of material parameters novel regimes of wave propagation emerge; we show that the transparency of the medium can be altered with the magnetization leading either to magnetically induced Hall opacity or Hall transparency of the ENZ. In our theoretical study, we demonstrate that surface waves at the interface between either a transparent or an opaque Hall medium and a homogeneous medium may, under certain conditions, be predominantly one way. Moreover, we predict that one-way photonic surface states may exist at the interface of an opaque Hall ENZ and a regular metal, giving rise to the possibility for backscattering immune wave propagation and isolation.
Spectroscopic investigation of wave driven microwave plasmas
International Nuclear Information System (INIS)
Wijtvliet, R.; Felizardo, E.; Tatarova, E.; Dias, F. M.; Ferreira, C. M.; Nijdam, S.; Veldhuizen, E. V.; Kroesen, G.
2009-01-01
Large H atom line broadening was found throughout the volume of surface wave generated He-H 2 and H 2 microwave plasmas at low pressures. The measured Doppler temperatures corresponding to the H β , H γ , H δ , H ε , and H ζ line profiles were found to be higher than the rotational temperature of the hydrogen molecular Fulcher-α band and the Doppler temperature of the 667.1 nm singlet He line. No excessive broadening has been found. The Lorentzian and Gaussian widths as determined by fitting the spectral lines with a Voigt profile increase with the principal quantum number of the upper level. In contrast, no such dependence for the Gaussian width has been observed in an Ar-H 2 discharge. No population inversion has been observed from measurements of the relative intensities of transitions within the Balmer series.
Wall-collision line broadening of molecular oxygen within nanoporous materials
Energy Technology Data Exchange (ETDEWEB)
Xu, Can T.; Lewander, Maerta; Andersson-Engels, Stefan; Svensson, Tomas; Svanberg, Sune [Department of Physics, Lund University, P. O. Box 118, SE-221 00 Lund (Sweden); Adolfsson, Erik [Ceramic Materials, SWEREA IVF, Box 104, SE-431 22 Moelndal (Sweden)
2011-10-15
Wall-collision broadening of near-infrared absorption lines of molecular oxygen confined in nanoporous zirconia is studied by employing high-resolution diode-laser spectroscopy. The broadening is studied for pores of different sizes under a range of pressures, providing new insights on how wall collisions and intermolecular collisions influence the total spectroscopic line profile. The pressure series show that wall-collision broadening is relatively more prominent under reduced pressures, enabling sensitive means to probe pore sizes of porous materials. In addition, we show that the total wall-collision-broadened profile strongly deviates from a Voigt profile and that wall-collision broadening exhibits an additive-like behavior to the pressure and Doppler broadening.
A Constrained Genetic Algorithm with Adaptively Defined Fitness Function in MRS Quantification
Papakostas, G. A.; Karras, D. A.; Mertzios, B. G.; Graveron-Demilly, D.; van Ormondt, D.
MRS Signal quantification is a rather involved procedure and has attracted the interest of the medical engineering community, regarding the development of computationally efficient methodologies. Significant contributions based on Computational Intelligence tools, such as Neural Networks (NNs), demonstrated a good performance but not without drawbacks already discussed by the authors. On the other hand preliminary application of Genetic Algorithms (GA) has already been reported in the literature by the authors regarding the peak detection problem encountered in MRS quantification using the Voigt line shape model. This paper investigates a novel constrained genetic algorithm involving a generic and adaptively defined fitness function which extends the simple genetic algorithm methodology in case of noisy signals. The applicability of this new algorithm is scrutinized through experimentation in artificial MRS signals interleaved with noise, regarding its signal fitting capabilities. Although extensive experiments with real world MRS signals are necessary, the herein shown performance illustrates the method's potential to be established as a generic MRS metabolites quantification procedure.
Energy Technology Data Exchange (ETDEWEB)
Lishi, Ma; Yonghua, Duan, E-mail: duanyh@kmust.edu.cn; Runyue, Li
2017-02-15
The structural and mechanical properties, Debye temperatures and anisotropic sound velocities of the Laves phases Al{sub 2}M (M=Mg, Ca, Sr and Ba) with C14-type structure were investigated using the first-principles corresponding calculations. The corresponding calculated structural parameters and formation enthalpies are in good agreement with the available theoretical values, and Al{sub 2}Ca has the best phase stability. The mechanical properties, including elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν, were deduced within the Voigt-Reuss-Hill approximation. The brittleness and ductility were estimated by the values of Poisson ratio, B/G and Cauchy pressure. Moreover, the elastic anisotropy was investigated by calculating and discussing several anisotropy indexes. Finally, the electronic structures were used to illustrate the bonding characteristics of C14-Al{sub 2}M (M=Mg, Ca, Sr and Ba) phases.
Bifurcation and chaos of an axially accelerating viscoelastic beam
International Nuclear Information System (INIS)
Yang Xiaodong; Chen Liqun
2005-01-01
This paper investigates bifurcation and chaos of an axially accelerating viscoelastic beam. The Kelvin-Voigt model is adopted to constitute the material of the beam. Lagrangian strain is used to account for the beam's geometric nonlinearity. The nonlinear partial-differential equation governing transverse motion of the beam is derived from the Newton second law. The Galerkin method is applied to truncate the governing equation into a set of ordinary differential equations. By use of the Poincare map, the dynamical behavior is identified based on the numerical solutions of the ordinary differential equations. The bifurcation diagrams are presented in the case that the mean axial speed, the amplitude of speed fluctuation and the dynamic viscoelasticity is respectively varied while other parameters are fixed. The Lyapunov exponent is calculated to identify chaos. From numerical simulations, it is indicated that the periodic, quasi-periodic and chaotic motions occur in the transverse vibrations of the axially accelerating viscoelastic beam
Synthesis of hydroxyapatite and structural refinement by X-ray diffraction
International Nuclear Information System (INIS)
Araujo, Jorge Correa de
2007-01-01
A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effects with an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals. (author)
Energy Technology Data Exchange (ETDEWEB)
Araujo, Jorge Correa de [Universidade do Estado do Rio de Janeiro (UERJ), Sao Goncalo, RJ (Brazil). Faculdade de Formacao de Professores; Sena, Lidia [Instituto Nacional de Metrologia, Normalizacao e Qualidade Industrial (INMETRO), Duque de Caxias, RJ (Brazil). Div. de Metrologia de Materiais; Bastos, Ivan Napoleao [Universidade do Estado do Rio de Janeiro (UERJ), Nova Friburgo, RJ (Brazil). Inst. Politecnico]. E-mail: jcaraujo@iprj.uerj.br; Soares, Gloria Dulce de Almeida [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil)
2007-07-01
A sample of hydroxyapatite was synthesized and its crystalline structure was analyzed by X-ray diffraction by means of the Rietveld method. Two functions were used to fit the peak profiles, modified Voigt (TCHZ) and Pearson VII. The occupational factors and lattice parameters obtained by both models show that the sample does not contain relevant cationic substitutions. The interatomic distances from Ca1 to oxygens O1, O2 and O3 were adequate for a pure hydroxyapatite without defect at site Ca1. Besides, the use of multiple lines in planes (300) and (002) associated with the model Pearson VII resulted in good agreement with the TCHZ model with respect to the size-strain effects with an ellipsoidal shape of crystallites. In conclusion, the procedures adopted in the synthesis of hydroxyapatite produced a pure and crystalline material. The experimental results of transmission electron microscopy confirmed the predicted shape of crystals. (author)
Frequency-comb-assisted precision laser spectroscopy of CHF{sub 3} around 8.6 μm
Energy Technology Data Exchange (ETDEWEB)
Gambetta, Alessio; Coluccelli, Nicola; Cassinerio, Marco; Fernandez, Toney Teddy; Gatti, Davide; Laporta, Paolo; Galzerano, Gianluca, E-mail: gianluca.galzerano@polimi.it [Dipartimento di Fisica - Politecnico di Milano and Istituto di Fotonica e Nanotecnologie - CNR, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Castrillo, Antonio; Fasci, Eugenio; Gianfrani, Livio [Dipartimento di Matematica e Fisica - Seconda Università di Napoli, Viale Lincoln 5, 81100 Caserta (Italy); Ceausu-Velcescu, Adina [Laboratoire de Mathématiques et Physique, Université de Perpignan, Via Domitia EA 4217, F-66860 Perpignan (France); Santamaria, Luigi; Di Sarno, Valentina [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); Maddaloni, Pasquale [CNR-INO, Istituto Nazionale di Ottica, Via Campi Flegrei 34, 80078 Pozzuoli, NA (Italy); INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); De Natale, Paolo [INFN, Istituto Nazionale di Fisica Nucleare, Sez. Firenze, Via G. Sansone 1, 50019 Sesto Fiorentino, FI (Italy); CNR-INO, Istituto Nazionale di Ottica, Largo E. Fermi 6, 50125 Firenze (Italy)
2015-12-21
We report a high-precision spectroscopic study of room-temperature trifluoromethane around 8.6 μm, using a CW quantum cascade laser phase-locked to a mid-infrared optical frequency comb. This latter is generated by a nonlinear down-conversion process starting from a dual-branch Er:fiber laser and is stabilized against a GPS-disciplined rubidium clock. By tuning the comb repetition frequency, several transitions falling in the υ{sub 5} vibrational band are recorded with a frequency resolution of 20 kHz. Due to the very dense spectra, a special multiple-line fitting code, involving a Voigt profile, is developed for data analysis. The combination of the adopted experimental approach and survey procedure leads to fractional accuracy levels in the determination of line center frequencies, down to 2 × 10{sup −10}. Line intensity factors, pressure broadening, and shifting parameters are also provided.
Demonstration of creep during filtration
DEFF Research Database (Denmark)
Christensen, Morten Lykkegaard; Bugge, Thomas Vistisen; Kirchheiner, Anders Løvenbalk
The classical filtration theory assumes a unique relationship between the local filter cake porosity and the local effective pressure. For a number of compressible materials, it has however been observed that during the consolidation stage this may not be the case. It has been found...... that the production of filtrate also depends on the characteristic time for the filter cake solids to deform. This is formulated in the Terzaghi-Voigt model in which a secondary consolidation is introduced. The secondary consolidation may be visualized by plots of the relative cake deformation (U) v.s. the square...... root of time. Even more clearly it is demonstrated by plotting the liquid pressure at the cake piston interface v.s. the relative deformation (to be shown). The phenomenon of a secondary consolidation processes is in short called creep. Provided that the secondary consolidation rate is of the same...
ExoCross: Spectra from molecular line lists
Yurchenko, Sergei N.; Al-Refaie, Ahmed; Tennyson, Jonathan
2018-03-01
ExoCross generates spectra and thermodynamic properties from molecular line lists in ExoMol, HITRAN, or several other formats. The code is parallelized and also shows a high degree of vectorization; it works with line profiles such as Doppler, Lorentzian and Voigt and supports several broadening schemes. ExoCross is also capable of working with the recently proposed method of super-lines. It supports calculations of lifetimes, cooling functions, specific heats and other properties. ExoCross converts between different formats, such as HITRAN, ExoMol and Phoenix, and simulates non-LTE spectra using a simple two-temperature approach. Different electronic, vibronic or vibrational bands can be simulated separately using an efficient filtering scheme based on the quantum numbers.
International Nuclear Information System (INIS)
Herman, R.M.
2011-01-01
A dole correlation function which incorporates velocity-changing (motional narrowing) effects and the effects of speed-dependent Lorentz relaxation rates into otherwise Voigt profile correlation functions is developed, based partly upon previous work by the author. For the first time simple closed expressions, which lend themselves to elementary calculation beginning only with the relevant parts of intermolecular interaction energies, are developed for the cubic time-dependent term within the exponent describing the decay of the correlation function. This term is of first order in perturbers number density, as are the Lorentz parameters, and is complex, thereby allowing for narrowing, changing in shape and asymmetry in the line profile. Soft and hard collisions play no explicit role, though both are variously present for each line. Quartic time dependencies are also discussed, though they are thought to be negligible in non hydrogen molecular spectroscopy. Finally, some comments are added about a relevant technique for hydrogen spectra
Radwan, Ahmed F.; Sobhy, Mohammed
2018-06-01
This work presents a nonlocal strain gradient theory for the dynamic deformation response of a single-layered graphene sheet (SLGS) on a viscoelastic foundation and subjected to a time harmonic thermal load for various boundary conditions. Material of graphene sheets is presumed to be orthotropic and viscoelastic. The viscoelastic foundation is modeled as Kelvin-Voigt's pattern. Based on the two-unknown plate theory, the motion equations are obtained from the dynamic version of the virtual work principle. The nonlocal strain gradient theory is established from Eringen nonlocal and strain gradient theories, therefore, it contains two material scale parameters, which are nonlocal parameter and gradient coefficient. These scale parameters have two different effects on the graphene sheets. The obtained deflection is compared with that predicted in the literature. Additional numerical examples are introduced to illustrate the influences of the two length scale coefficients and other parameters on the dynamic deformation of the viscoelastic graphene sheets.
Application of gamma-spectrometry to post irradiation examination
International Nuclear Information System (INIS)
Kim, S.K.; Huh, Y.H.; Park, K.J.
1982-01-01
A areat variety of nuclear gamma rays emitted from fission and activation products of spent nuclear fuel contains much information that can be elicited without affecting the integrity of the fuel elements. In the present work, a versatile code CAERI was developed which locates peaks and calculates their areas for X-rays as well as gamma rays using elegant features of some widely used programs for gamma ray peak fitting. CAERI coded in FORTRAN used infinite series approximation more accurate than other workers' various, simple, piecewise series approximations for evaluation of the Voigt function which represents the X-ray peak with nonneglible natural line width. CAERI can handle even a complex multiplet consisting of peaks from X-rays and rays in arbitrary mixture, which one often encounters in the isotopic analysis of heavy elements such as U and Pu. (Author)
International Nuclear Information System (INIS)
Moreno, J.M.; Quintanilla, M.; Mar, S.
1978-01-01
A deconvolution method of registered profile on a Fabry-Perot spectrometer is developed, when the actual profile of the source is a Voigt pattern together with a continuous background. The reliability and accuracy of the method is tested with theoreticaly simulated profiles. The method is applied both to measure the real line profiles and to find the Fabry-Perot parameters, as a test of its validity on studies of experimental profiles. Both measure types -source profile and apparatus function- are made simultaneously by means of analysis of the variations of registered profile, at 6438.5A Cd line and 6328A He-Ne laser line, varying the optical path between interferometer mirrors. (author) [es
Zhang, D. P.; Lei, Y.; Shen, Z. B.
2017-12-01
The effect of longitudinal magnetic field on vibration response of a sing-walled carbon nanotube (SWCNT) embedded in viscoelastic medium is investigated. Based on nonlocal Euler-Bernoulli beam theory, Maxwell's relations, and Kelvin viscoelastic foundation model, the governing equations of motion for vibration analysis are established. The complex natural frequencies and corresponding mode shapes in closed form for the embedded SWCNT with arbitrary boundary conditions are obtained using transfer function method (TFM). The new analytical expressions for the complex natural frequencies are also derived for certain typical boundary conditions and Kelvin-Voigt model. Numerical results from the model are presented to show the effects of nonlocal parameter, viscoelastic parameter, boundary conditions, aspect ratio, and strength of the magnetic field on vibration characteristics for the embedded SWCNT in longitudinal magnetic field. The results demonstrate the efficiency of the proposed methods for vibration analysis of embedded SWCNTs under magnetic field.
Ali, Md. Lokman; Rahaman, Md. Zahidur
2018-04-01
By using first principles calculation dependent on the density functional theory (DFT), we have investigated the mechanical, structural properties and the Debye temperature of Fe2ScM (M=P and As) compounds under various pressures up to 60 GPa. The optical properties have been investigated under zero pressure. Our calculated optimized structural parameters of both the materials are in good agreement with other theoretical predictions. The calculated elastic constants show that Fe2ScM (M=P and As) compounds are mechanically stable under external pressure below 60 GPa. From the elastic constants, the shear modulus G, the bulk modulus B, Young’s modulus E, anisotropy factor A and Poisson’s ratio ν are calculated by using the Voigt-Reuss-Hill approximation. The Debye temperature and average sound velocities are also investigated from the obtained elastic constants. The detailed analysis of all optical functions reveals that both compounds are good dielectric material.
International Nuclear Information System (INIS)
Deguchi, K; Imagawa, T; Shikama, T; Hasuo, M
2009-01-01
We have measured the relaxation rate of alignment of neon atoms in a 2p 2 (in Paschen notation) level, which were excited by a linearly polarized laser pulse in a glow discharge plasma at 77 K, in a magnetic field of up to 3 T in the Voigt configuration. The relaxation rate decreased with an increase in the magnetic field strength of up to 0.5 T and showed no magnetic field dependence above 0.5 T. We developed a Monte Carlo simulation method to calculate alignment relaxation, or disalignment, by radiation re-absorption of atomic resonance lines in a magnetic field. The simulated result was found to be consistent with the observed magnetic field dependence. We analysed the results of the simulation from a point of competition between the Zeeman splitting and the Doppler broadening of the transition lines from the 2p 2 level.
Directory of Open Access Journals (Sweden)
Rossikhin Yury A.
2018-01-01
Full Text Available Non-linear damped vibrations of a cylindrical shell embedded into a fractional derivative medium are investigated for the case of the combinational internal resonance, resulting in modal interaction, using two different numerical methods with further comparison of the results obtained. The damping properties of the surrounding medium are described by the fractional derivative Kelvin-Voigt model utilizing the Riemann-Liouville fractional derivatives. Within the first method, the generalized displacements of a coupled set of nonlinear ordinary differential equations of the second order are estimated using numerical solution of nonlinear multi-term fractional differential equations by the procedure based on the reduction of the problem to a system of fractional differential equations. According to the second method, the amplitudes and phases of nonlinear vibrations are estimated from the governing nonlinear differential equations describing amplitude-and-phase modulations for the case of the combinational internal resonance. A good agreement in results is declared.
[Studies on the mechanical properties of the knee ligament].
Kubotera, D
1987-04-01
To study mechanical properties of the knee ligaments, tension tests at various speeds were performed on the knee of a dog with only the collateral ligament. The results showed that the tensile force was greater in high speed than in low speed test. The difference may be caused in a viscous property of the ligament. The mechanical properties of ligaments can therefore be treated as those of viscoelastic materials and expressed by a modified Voigt model consisting of a non-linear spring element and a dash pot component. Observations regarding the ultrastructure of human knee ligaments using an electron scanning microscope revealed wavy bundles of collagen fiber connected with coarse fibers like network running in parallel with the long axis as the main structure. The above structure and properties were considered to be the decisive factors in the mechanical actions of the knee ligament.
Predicting the Coupling Properties of Axially-Textured Materials
Directory of Open Access Journals (Sweden)
María E. Fuentes-Montero
2013-10-01
Full Text Available A description of methods and computer programs for the prediction of “coupling properties” in axially-textured polycrystals is presented. Starting data are the single-crystal properties, texture and stereography. The validity and proper protocols for applying the Voigt, Reuss and Hill approximations to estimate coupling properties effective values is analyzed. Working algorithms for predicting mentioned averages are given. Bunge’s symmetrized spherical harmonics expansion of orientation distribution functions, inverse pole figures and (single and polycrystals physical properties is applied in all stages of the proposed methodology. The established mathematical route has been systematized in a working computer program. The discussion of piezoelectricity in a representative textured ferro-piezoelectric ceramic illustrates the application of the proposed methodology. Polycrystal coupling properties, predicted by the suggested route, are fairly close to experimentally measured ones.
Predicting the Coupling Properties of Axially-Textured Materials
Fuentes-Cobas, Luis E.; Muñoz-Romero, Alejandro; Montero-Cabrera, María E.; Fuentes-Montero, Luis; Fuentes-Montero, María E.
2013-01-01
A description of methods and computer programs for the prediction of “coupling properties” in axially-textured polycrystals is presented. Starting data are the single-crystal properties, texture and stereography. The validity and proper protocols for applying the Voigt, Reuss and Hill approximations to estimate coupling properties effective values is analyzed. Working algorithms for predicting mentioned averages are given. Bunge’s symmetrized spherical harmonics expansion of orientation distribution functions, inverse pole figures and (single and polycrystals) physical properties is applied in all stages of the proposed methodology. The established mathematical route has been systematized in a working computer program. The discussion of piezoelectricity in a representative textured ferro-piezoelectric ceramic illustrates the application of the proposed methodology. Polycrystal coupling properties, predicted by the suggested route, are fairly close to experimentally measured ones. PMID:28788370
Linking strain anisotropy and plasticity in copper metallization
International Nuclear Information System (INIS)
Murray, Conal E.; Jordan-Sweet, Jean; Priyadarshini, Deepika; Nguyen, Son
2015-01-01
The elastic anisotropy of copper leads to significant variation in the x-ray elastic constants (XEC), which link diffraction-based strain measurements to stress. An accurate depiction of the mechanical response in copper thin films requires a determination of an appropriate grain interaction model that lies between Voigt and Reuss limits. It is shown that the associated XEC weighting fraction, x*, between these limits provides a metric by which strain anisotropy can be quantified. Experimental values of x*, as determined by a linear regression scheme of diffraction data collected from multiple reflections, reveal the degree of strain anisotropy and its dependence on plastic deformation induced during in-situ and ex-situ thermal treatments
Bidaux, Yves; Bismuto, Alfredo; Patimisco, Pietro; Sampaolo, Angelo; Gresch, Tobias; Strubi, Gregory; Blaser, Stéphane; Tittel, Frank K; Spagnolo, Vincenzo; Muller, Antoine; Faist, Jérôme
2016-11-14
We present a single mode multi-section quantum cascade laser source composed of three different sections: master oscillator, gain and phase section. Non-uniform pumping of the QCL's gain reveals that the various laser sections are strongly coupled. Simulations of the electronic and optical properties of the laser (based on the density matrix and scattering matrix formalisms, respectively) were performed and a good agreement with measurements is obtained. In particular, a pure modulation of the laser output power can be achieved. This capability of the device is applied in tunable-laser spectroscopy of N2O where background-free quartz enhanced photo acoustic spectral scans with nearly perfect Voigt line shapes for the selected absorption line are obtained.
Laser absorption spectroscopy for measurement of He metastable atoms of a microhollow cathode plasma
Ueno, Keisuke; Kamebuchi, Kenta; Kakutani, Jiro; Matsuoka, Leo; Namba, Shinichi; Fujii, Keisuke; Shikama, Taiichi; Hasuo, Masahiro
2018-01-01
We generated a 0.3-mm-diameter DC, hollow-cathode helium discharge in a gas pressure range of 10-80 kPa. In discharge plasmas, we measured position-dependent laser absorption spectra for helium 23S1-23P0 transition with a spatial resolution of 55 µm. From the results of the analysis of the measured spectra using Voigt functions and including both the Doppler and collision broadening, we produced two-dimensional maps of the metastable 23S1 atomic densities and gas temperatures of the plasmas. We found that, at all pressures, the gas temperatures were approximately uniform in space with values in the range of 400-1500 K and the 23S1 atomic densities were ˜1019 m-3. We also found that the two-dimensional density distribution profiles became ring-shaped at high gas pressures, which is qualitatively consistent with the two-dimensional fluid simulation results.
Computational expressions for signals in frequency-modulation spectroscopy.
Di Rosa, Michael D; Reiten, M T
2015-06-01
General expressions for the signals in frequency-modulation spectroscopy (FMS) appear in the literature but are often reduced to simple analytical equations following the assumption of a weak modulation index. This is little help to the experimentalist who wants to predict signals for modulation depths of the order of unity or greater, where strong FMS signals reside. Here, we develop general formulas for FMS signals in the case of an absorber with a Voigt line shape and then link these expressions to an example and existing numerical code for the line shape. The resulting computational recipe is easy to implement and exercised here to show where the larger FMS signals are found over the coordinates of modulation index and modulation frequency. One can also estimate from provided curves the in-phase FMS signal over a wide range of modulation parameters at either the Lorentzian-broadening or Doppler-broadening limit, or anywhere in between by interpolation.
Lin, Jeffrey Chun-Hui
2011-06-01
The glass transition temperature of as-deposited parylene-C is first measured to be 50°C with a ramping-temperature-dependent modulus experiment. The creep behavior of parylene-C film in the primary and secondary creep region is then investigated below and above this glass transition temperature using a dynamic mechanical analysis (DMA) machine Q800 from TA instruments at 8 different temperatures: 10, 25, 40, 60, 80, 100, 120 and 150°C. The Burger\\'s model, which is the combined Maxwell model and Kelvin-Voigt model, fits well with our primary and secondary creep data. Accordingly, the results show that there\\'s little or no creep below the glass transition temperature. Above the glass transition temperature, the primary creep and creep rate increases with the temperature, with a retardation time constant around 6 minutes. © 2011 IEEE.
Bounds and self-consistent estimates for elastic constants of polycrystals of hcp solid He {}^{4}
Energy Technology Data Exchange (ETDEWEB)
Berryman, James G.
2012-03-01
Recent advances in methods for computing both Hashin-Shtrikman bounds and related selfconsistent (or CPA) estimates of elastic constants for polycrystals composed of randomly oriented crystals can be applied successfully to hexagonal close packed solid He{sup 4}. In particular, since the shear modulus C{sub 44} of hexagonal close-packed solid He is known to undergo large temperature variations when 20 mK {<=} T {<=} 200 mK, bounds and estimates computed with this class of effective medium methods, while using C{sub 44} {r_arrow} 0 as a proxy for melting, are found to be both qualitatively and quantitatively very similar to prior results obtained using Monte Carlo methods. Hashin- Shtrikman bounds provide significantly tighter constraints on the polycrystal behavior than do the traditional Voigt and Reuss bounds.
Coupling mechanical tension and GTPase signaling to generate cell and tissue dynamics
Zmurchok, Cole; Bhaskar, Dhananjay; Edelstein-Keshet, Leah
2018-07-01
Regulators of the actin cytoskeleton such Rho GTPases can modulate forces developed in cells by promoting actomyosin contraction. At the same time, through mechanosensing, tension is known to affect the activity of Rho GTPases. What happens when these effects act in concert? Using a minimal model (1 GTPase coupled to a Kelvin–Voigt element), we show that two-way feedback between signaling (‘RhoA’) and mechanical tension (stretching) leads to a spectrum of cell behaviors, including contracted or relaxed cells, and cells that oscillate between these extremes. When such ‘model cells’ are connected to one another in a row or in a 2D sheet (‘epithelium’), we observe waves of contraction/relaxation and GTPase activity sweeping through the tissue. The minimal model lends itself to full bifurcation analysis, and suggests a mechanism that explains behavior observed in the context of development and collective cell behavior.
Intensities, broadening and narrowing parameters in the ν3 band of methane
Es-sebbar, Et-touhami
2014-12-01
The P-branch of methane\\'s ν3 band is probed to carry out an extensive study of the 2905-2908cm-1 infrared spectral region. Absolute line intensities as well as N2-, O2-, H2-, He-, Ar- and CO2-broadening coefficients are determined for nine transitions at room temperature. Narrowing parameters due to the Dicke effect have also been investigated. A narrow emission line-width (~0.0001cm-1) difference-frequency-generation (DFG) laser system is used as the tunable light source. To retrieve the CH4 spectroscopic parameters, Voigt and Galatry profiles were used to simulate the measured line shape of the individual transitions.
Stretching of red blood cells at high strain rates
Mancuso, J. E.; Ristenpart, W. D.
2017-10-01
Most work on the mechanical behavior of red blood cells (RBCs) in flow has focused on simple shear flows. Relatively little work has examined RBC deformations in the physiologically important extensional flow that occurs at the entrance to a constriction. In particular, previous work suggests that RBCs rapidly stretch out and then retract upon entering the constriction, but to date no model predicts this behavior for the extremely high strain rates typically experienced there. In this Rapid Communication, we use high speed video to perform systematic measurements of the dynamic stretching behavior of RBCs as they enter a microfluidic constriction. We demonstrate that both the Kelvin-Voigt and Skalak viscoelastic models capture the observed stretching dynamics, up to strain rates as high as 2000 s-1. The results indicate that the effective elastic modulus of the RBC membrane at these strain rates is an order of magnitude larger than moduli measured by micropipette aspiration or other low strain rate techniques.
International Nuclear Information System (INIS)
Zhang, Da Peng; Lei, Yong Jun; Shen, Zhi Bin; Wang, Cheng Yuan
2017-01-01
Vibration responses were investigated for a viscoelastic Single-walled carbon nanotube (visco-SWCNT) resting on a viscoelastic foundation. Based on the nonlocal Euler-Bernoulli beam model, velocity-dependent external damping and Kelvin viscoelastic foundation model, the governing equations were derived. The Transfer function method (TFM) was then used to compute the natural frequencies for general boundary conditions and foundations. In particular, the exact analytical expressions of both complex natural frequencies and critical viscoelastic parameters were obtained for the Kelvin-Voigt visco-SWCNTs with full foundations and certain boundary conditions, and several physically intuitive special cases were discussed. Substantial nonlocal effects, the influence of geometric and physical parameters of the SWCNT and the viscoelastic foundation were observed for the natural frequencies of the supported SWCNTs. The study demonstrates the efficiency and robustness of the developed model for the vibration of the visco-SWCNT-viscoelastic foundation coupling system
Sajid, Muhammad Bilal
2014-11-01
Linestrengths, N2-, Ar-, He- and self-broadening coefficients of acetylene have been measured at 296K in the P branch of the ν4+ν5 combination band for 25 rotational transitions. The effect of gas temperature is studied over 296-683K for five transitions to allow the determination of the temperature dependent exponent n for N2- and Ar-broadening coefficients. These measurements were performed using a continuous-wave quantum cascade laser (cw-QCL) operating over 1253-1310cm-1. Spectroscopic parameters were obtained by fitting absorption spectra using Voigt, Galatry and Rautian profiles. Linestrength and broadening results are compared with previous studies available in literature for the ν4+ν5 combination band and other vibrational bands of acetylene. © 2014 Elsevier Ltd.
Fluence behavior of polyethylene films irradiated with high energy electrons
International Nuclear Information System (INIS)
Pino, Eddy Segura; Silva, Leonardo G. Andrade e
1999-01-01
Polymers are viscoelastic materials at all temperatures, so that mechanical loads induce time dependable deformations. The recovery of these deformations, on load release, take some time and it is not always recovered completely. The main objective of this work was to analyse the creep behavior of electron irradiated polyethylene films. From the experimental results, it was sated that polyethylene creeps less with an increase on irradiation dose and also that creep recovery in this material increases with doses but it is not complete. This behavior can be attributed to the crosslinking effect witch stabilize elements of the molecular structure of the polyethylene, thus reducing their mobility and so inhibiting the creep mechanism. The partial creep recovery could be also attributed to the reticulation effect and to the polyethylene plastic behavior. Additional information on the creep behavior was obtained by fitting the experimental data with exponential functions and evaluating the mathematical parameters with a modified Kelvin-Voigt mechanical model. (author)
Gold awards for CERN's top suppliers!
2003-01-01
CERN's awards to the LHC project's best suppliers are now into their second year. Three companies received 'Golden Hadrons' for 2003. The Golden Hadron awards were presented to the delighted representatives of the winning firms by LHC Project Leader Lyn Evans on Friday 16 May. Only three out of the LHC's four hundred suppliers were lucky enough to receive a gold award. The consortium IHI (Japan)-Linde Kryotechnik (Switzerland), the Belgian company JDL Technologies and the Japanese firm Furukawa Electric Company were rewarded not only for their technical and financial achievements but also for their compliance with contractual deadlines. The 2003 Golden Hadron winners with Lyn Evans. From left to right: Armin Senn, Thomas Voigt, Kirkor Kurtcuoglu of LINDE KRYOTECHNIK ; Tadaaki Honda, Project Leader and Motoki Yoshinaga, Associate Director of IHI Corporation ; Lyn Evans, LHC Project Leader; Shinichiro Meguro, Managing Director of FURUKAWA ELECTRIC COMPANY ; Nobuyoshi Saji, Consulting Engineer of IHI Corporatio...
CERT TST December 2015 Visit Summary
Energy Technology Data Exchange (ETDEWEB)
Little, Robert Currier [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Bailey, Teresa S. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Gamblin, G. Todd [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Olinger, Chad Tracy [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Pautz, Shawn D. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Williams, Alan B. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2016-01-25
The annual PSAAP II TST visit to Texas A&M’s CERT Center was held on December 1-3, 2015. The agenda for the visit is attached. Non-TAMU attendees were: TST Members – Teresa Bailey (LLNL), Todd Gamblin (LLNL), Bob Little (LANL) – Chair, Chad Olinger (LANL), Shawn Pautz (SNL), Alan Williams (SNL);Other Lab staff – Skip Kahler (LANL), Ana Kupresanin (LLNL), and Rob Lowrie (LANL); AST Members – Nelson Hoffman (LANL) and Bob Voigt (Leidos) The TST wishes to express our appreciation to all involved with CERT for the high-quality posters and presentations and for the attention to logistics that enabled a successful visit. We have broken our comments into four sections: (1) Kudos, (2) Recommendations, (3) Feedback on Priorities for April Review, and (4) Follow-Up Activities with Labs.
DEFF Research Database (Denmark)
Noer, Vibeke Røn
(Christensen, 2013), this presentation will focus on ‘what’s happening in the classroom’ when classroom is ‘school’ among fellow students opposed to ‘real nursing practice’ among future colleagues. Focusing on student strategies in the classroom, the presentation will further elaborate on the inherent...... & Perrenoud, 2006). In Denmark alone changes have been made numerously times in the last two decades. Concurrently, a considerable amount of studies has been published focusing on the nursing education, stressing a call for transformation. Division of learning contexts into clinical and classroom settings...... is a strong marker of the nursing education and has as such also been of interest for research. There is a large number of studies (e.g. Larsen, 2000; Johnsen, 2003; Kragelund, 2006; Voigt, 2007; Henriksen, 2009; Højbjerg, 2011) that explore the learning contexts in the nursing education. However, most...
Quantitative X ray analysis system. User's manual and guide to X ray fluorescence technique
International Nuclear Information System (INIS)
2009-01-01
This guide covers trimmed and re-arranged version 3.6 of the Quantitative X ray Analysis System (QXAS) software package that includes the most frequently used methods of quantitative analysis. QXAS is a comprehensive quantitative analysis package that has been developed by the IAEA through research and technical contracts. Additional development has also been carried out in the IAEA Laboratories in Seibersdorf where QXAS was extensively tested. New in this version of the manual are the descriptions of the Voigt-profile peak fitting, the backscatter fundamental parameters' and emission-transmission methods of chemical composition analysis, an expanded chapter on the X ray fluorescence physics, and completely revised and increased number of practical examples of utilization of the QXAS software package. The analytical data accompanying this manual were collected in the IAEA Seibersdorf Laboratories in the years 2006/2007
Energy Technology Data Exchange (ETDEWEB)
Permoon, M. R.; Haddadpour, H. [Sharif University of Tech, Tehran (Iran, Islamic Republic of); Rashidinia, J.; Parsa, A.; Salehi, R. [Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)
2016-07-15
In this paper, the forced vibrations of the fractional viscoelastic beam with the Kelvin-Voigt fractional order constitutive relationship is studied. The equation of motion is derived from Newton's second law and the Galerkin method is used to discretize the equation of motion in to a set of linear ordinary differential equations. For solving the discretized equations, the radial basis functions and Sinc quadrature rule are used. In order to show the effectiveness and accuracy of this method, some test problem are considered, and it is shown that the obtained results are in very good agreement with exact solution. In the following, the proposed numerical solution is applied to exploring the effects of fractional parameters on the response of the beam and finally some conclusions are outlined.
The elastic constants and anisotropy of superconducting MgCNi3 and CdCNi3 under different pressure
Feng, Huifang
2013-11-23
The second-order elastic constants (SOECs) and third-order elastic constants (TOECs) of MgCNi3 and CdCNi3 are presented by using first-principles methods combined with homogeneous deformation theory. The Voigt-Reuss-Hill (VRH) approximation are used to calculate the bulk modulus B, shear modulus G, averaged Young\\'s modulus E and Poisson\\'s ratio ν for polycrystals and these effective modulus are consistent with the experiments. The SOECs under different pressure of MgCNi3 and CdCNi3 are also obtained based on the TOECs. Furthermore, the Zener anisotropy factor, Chung-Buessem anisotropy index, and the universal anisotropy index are used to describe the anisotropy of MgCNi3 and CdCNi3. The anisotropy of Young\\'s modulus of single-crystal under different pressure is also presented. © 2013 Springer Science+Business Media New York.
DEFF Research Database (Denmark)
Ardenkjær-Larsen, J. H.; Laursen, I; Leunbach, I.
1998-01-01
Parameters of relevance to oximetry with Overhauser magnetic resonance imaging (OMRI) have been measured for three single electron contrast agents of the triphenylmethyl type. The single electron contrast agents are stable and water soluble. Magnetic resonance properties of the agents have been...... examined with electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), and dynamic nuclear polarization (DNP) at 9.5 mT in water, isotonic saline, plasma, and blood at 23 and 37°C. The relaxivities of the agents are about 0.2–0.4 mM−1s−1and the DNP enhancements extrapolate close...... to the dipolar limit. The agents have a single, narrow EPR line, which is analyzed as a Voigt function. The linewidth is measured as a function of the agent concentration and the oxygen concentration. The concentration broadenings are about 1–3 μT/mM and the Lorentzian linewidths at infinite dilution are less...
Radial magnetic compression in the expelled jet of a plasma deflagration accelerator
International Nuclear Information System (INIS)
Loebner, Keith T. K.; Underwood, Thomas C.; Mouratidis, Theodore; Cappelli, Mark A.
2016-01-01
A spectroscopic study of a pulsed plasma deflagration accelerator is carried out that confirms the existence of a strong compression in the emerging jet at the exit plane of the device. An imaging spectrometer is used to collect broadened Hα emission from a transaxial slice of the emerging jet at high spatial resolution, and the radial plasma density profile is computed from Voigt fits of the Abel inverted emissivity profiles. The plasma temperature, determined via Doppler broadening of impurity line emission, is compared against the temperature predictions of a radial magnetohydrodynamic equilibrium model applied to the measured density profiles. Empirical scaling laws developed for the plasma density, combined with the measured and predicted temperatures, indicate that a radially equilibrated Z-pinch is formed within the expelled plasma jet at the exit plane during the deflagration process.
Internal frictions and their application in the supervision and inspection of a manufacture
International Nuclear Information System (INIS)
Bourgain, L.; Samson, G.; Blay, D.
1975-01-01
The internal frictions of materials subjected to flexion or compression waves were studied. In the first part of the report, devoted to the theoretical aspect of the problem, an attempt is made to estimate how much of the total friction measured is exterior to the structure and how much is intrinsic. The mathematical models generally used to account for these phenomena, those of Maxwell and Voigt, were applied for this purpose. Part two deals with measurement methods and precautions necessary if good precision and reproducible experimental results are required. The last part gives several examples of application. It is shown how internal damping measurements are used to detect variations in a given manufacture. In the application specific to sintered materials a physical explanation is tentatively put forward to account for the peaks recorded at middle frequency (between 1000 and 10000 hertz) in the damping spectrum; these are connected with interface phenomena between the grains, sometimes known as surface/volume effect [fr
International Nuclear Information System (INIS)
Liu Yaozong; Yu Dianlong; Zhao Honggang; Wen Jihong; Wen Xisen
2008-01-01
Wave propagation in two-dimensional phononic crystals (PCs) with viscoelasticity is investigated using a finite-difference-time-domain (FDTD) method. The viscoelasticity is evaluated using the Kelvin-Voigt model with fractional derivatives (FDs) so that both the dispersion and dissipation are considered. Numerical approximation of FDs is integrated into the FDTD scheme to simulate wave propagation in such PCs. All the constituent materials are treated as isotropic and homogeneous. The gaps are substantially displaced and widened and the attenuation is noticeably enhanced due to the dispersion and dissipation of host material and the complicated multiple scattering between scatterers. These results indicate that the viscoelasticity of the damping host has significant influence on wave propagation in PCs and should be considered
Energy Technology Data Exchange (ETDEWEB)
Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)
2009-07-01
A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)
International Nuclear Information System (INIS)
Hannachi, R.; Cressault, Y.; Teulet, Ph.; Gleizes, A.; Lakhdar, Z. Ben
2008-01-01
The resonance escape factors for the lines emitted by a neutral calcium atom Ca I at 4226.73 A and of ionic calcium Ca II at 3933.66 A and at 3968.47 A are calculated assuming a Voigt profile and in the case of CaCl 2 -water plasma. The dependence of the escape factor on the optical thickness f 0 from the line center which itself depends on the two main spectral line shape broadening mechanisms (pressure and Doppler effects) are considered. The variation of the resonance escape factors with the temperature, the CaCl 2 molar proportion and the size of the plasma are also investigated. This calculation is useful for the application of Laser-Induced Breakdown Spectroscopy in the quantitative analysis of elemental composition. Its application allows us to reduce the non-linearities in the relation between resonance lines intensities of calcium in our case and its concentration
Sladkov, Maksym; Bakker, M P; Chaubal, A U; Reuter, D; Wieck, A D; van der Wal, C H
2011-04-01
We present the design and operation of a fiber-based cryogenic confocal microscope. It is designed as a compact cold-finger that fits inside the bore of a superconducting magnet, and which is a modular unit that can be easily swapped between use in a dilution refrigerator and other cryostats. We aimed at application in quantum optical experiments with electron spins in semiconductors and the design has been optimized for driving with and detection of optical fields with well-defined polarizations. This was implemented with optical access via a polarization maintaining fiber together with Voigt geometry at the cold finger, which circumvents Faraday rotations in the optical components in high magnetic fields. Our unit is versatile for use in experiments that measure photoluminescence, reflection, or transmission, as we demonstrate with a quantum optical experiment with an ensemble of donor-bound electrons in a thin GaAs film. © 2011 American Institute of Physics
International Nuclear Information System (INIS)
Andrade, M.C.; Assis, J.T.; Pereira, F.R.
2009-01-01
A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO 3 formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)
Elastic properties of uniaxial-fiber reinforced composites - General features
Datta, Subhendu; Ledbetter, Hassel; Lei, Ming
The salient features of the elastic properties of uniaxial-fiber-reinforced composites are examined by considering the complete set of elastic constants of composites comprising isotropic uniaxial fibers in an isotropic matrix. Such materials exhibit transverse-isotropic symmetry and five independent elastic constants in Voigt notation: C(11), C(33), C(44), C(66), and C(13). These C(ij) constants are calculated over the entire fiber-volume-fraction range 0.0-1.0, using a scattered-plane-wave ensemple-average model. Some practical elastic constants such as the principal Young moduli and the principal Poisson ratios are considered, and the behavior of these constants is discussed. Also presented are the results for the four principal sound velocities used to study uniaxial-fiber-reinforced composites: v(11), v(33), v(12), and v(13).
High temperature and high pressure gas cell for quantitative spectroscopic measurements
International Nuclear Information System (INIS)
Christiansen, Caspar; Stolberg-Rohr, Thomine; Fateev, Alexander; Clausen, Sønnik
2016-01-01
A high temperature and high pressure gas cell (HTPGC) has been manufactured for quantitative spectroscopic measurements in the pressure range 1–200 bar and temperature range 300–1300 K. In the present work the cell was employed at up to 100 bar and 1000 K, and measured absorption coefficients of a CO_2–N_2 mixture at 100 bar and 1000 K are revealed for the first time, exceeding the high temperature and pressure combinations previously reported. This paper discusses the design considerations involved in the construction of the cell and presents validation measurements compared against simulated spectra, as well as published experimental data. - Highlights: • A ceramic gas cell designed for gas measurements up to 1300 K and 200 bar. • The first recorded absorption spectrum of CO_2 at 1000 K and 101 bar is presented. • Voigt profiles might suffice in the modeling of radiation from CO_2 in combustion.
Berselli, Luigi C.; Spirito, Stefano
2018-06-01
Obtaining reliable numerical simulations of turbulent fluids is a challenging problem in computational fluid mechanics. The large eddy simulation (LES) models are efficient tools to approximate turbulent fluids, and an important step in the validation of these models is the ability to reproduce relevant properties of the flow. In this paper, we consider a fully discrete approximation of the Navier-Stokes-Voigt model by an implicit Euler algorithm (with respect to the time variable) and a Fourier-Galerkin method (in the space variables). We prove the convergence to weak solutions of the incompressible Navier-Stokes equations satisfying the natural local entropy condition, hence selecting the so-called physically relevant solutions.
Lawton, Pat
2004-01-01
The objective of this work was to support the design of improved IUE NEWSIPS high dispersion extraction algorithms. The purpose of this work was to evaluate use of the Linearized Image (LIHI) file versus the Re-Sampled Image (SIHI) file, evaluate various extraction, and design algorithms for evaluation of IUE High Dispersion spectra. It was concluded the use of the Re-Sampled Image (SIHI) file was acceptable. Since the Gaussian profile worked well for the core and the Lorentzian profile worked well for the wings, the Voigt profile was chosen for use in the extraction algorithm. It was found that the gamma and sigma parameters varied significantly across the detector, so gamma and sigma masks for the SWP detector were developed. Extraction code was written.
International Nuclear Information System (INIS)
Ponce, C A; Casali, R A; Caravaca, M A
2008-01-01
By means of the ab initio all-electron new full-potential linear-muffin-tin orbitals method, calculations were made for elastic constants C 11 , C 12 and C 44 for Si, ZrO 2 and HfO 2 in their cubic phase, and constants C 11 , C 22 , C 33 , C 12 , C 13 , C 23 , C 44 , C 55 and C 66 for HfO 2 in its orthorhombic phase. Using the Voigt and Reuss theory, estimations were made for polycrystals of their bulk, shear and Young moduli, and Poisson coefficients. The speed of elastic wave propagations and Debye temperatures were estimated for polycrystals built from Si and the above mentioned compounds. The semicore 4f 14 electrons should be included in the valence set of Hf atom in this all-electron approach if accurate results for elastic properties under pressures are looked for
Energy Technology Data Exchange (ETDEWEB)
Tzannis, A P; Beaud, P; Frey, H M; Gerber, T; Mischler, B; Radi, P P [Paul Scherrer Inst. (PSI), Villigen (Switzerland)
1997-06-01
Resonant Holographic Interferometry is a method based on the anomalous dispersion of light having a frequency close to an electronic transition of a molecule. We propose a novel single-laser, two-colour setup for recording resonant holograms and apply it to 2D species concentration measurements. The second colour is generated by optical phase-conjugation from Stimulated Brillouin scattering in a cell. Phase-Conjugate Resonant Holographic Interferometry (PCRHI) is demonstrated in a 2D NH{sub 3}/O{sub 2} flame yielding interferograms that contain information on the NH radical distribution in the flame. Experimental results are quantified by applying a numerical computation of the Voigt profiles. (author) 1 fig., 3 refs.
Tunable omnidirectional absorber and mode splitter based on semiconductor photonic crystal
International Nuclear Information System (INIS)
Ding, Guo-Wen; Liu, Shao-Bin; Zhang, Hai-Feng; Kong, Xiang-Kun; Li, Hai-Ming
2015-01-01
In this paper, the properties of one-dimensional (1D) photonic crystals (PCs) composed of the semiconductor (GaAs) and dielectric layers are theoretically investigated by the transfer matrix method (TMM). The absorption of semiconductor layers is investigated theoretically. Due to the magneto-optical Voigt effect, the dielectric constant of the semiconductor is modified differently in different modes and frequency ranges. If the frequency range of the incident wave is larger than the plasma frequency, TE and TM modes of the incident wave will be absorbed in a wide incident angle. TM wave will be absorbed but TE wave will be reflected while the frequency range is less than the plasma frequency. The absorption of semiconductor can also be tuned by varying the external magnetic field. The proposed PCs have a reconfigurable application to design a tunable omnidirectional absorber and mode splitter at same time
Canagasabey, Albert; Michie, Andrew; Canning, John; Holdsworth, John; Fleming, Simon; Wang, Hsiao-Chuan; Aslund, Mattias L
2011-01-01
Linewidth measurements of a distributed feedback (DFB) fibre laser are made using delayed self heterodyne interferometry (DHSI) with both Mach-Zehnder and Michelson interferometer configurations. Voigt fitting is used to extract and compare the Lorentzian and Gaussian linewidths and associated sources of noise. The respective measurements are w(L) (MZI) = (1.6 ± 0.2) kHz and w(L) (MI) = (1.4 ± 0.1) kHz. The Michelson with Faraday rotator mirrors gives a slightly narrower linewidth with significantly reduced error. This is explained by the unscrambling of polarisation drift using the Faraday rotator mirrors, confirmed by comparing with non-rotating standard gold coated fibre end mirrors.
Nguyen, Vu-Hieu; Tran, Tho N H T; Sacchi, Mauricio D; Naili, Salah; Le, Lawrence H
2017-08-01
We present a semi-analytical finite element (SAFE) scheme for accurately computing the velocity dispersion and attenuation in a trilayered system consisting of a transversely-isotropic (TI) cortical bone plate sandwiched between the soft tissue and marrow layers. The soft tissue and marrow are mimicked by two fluid layers of finite thickness. A Kelvin-Voigt model accounts for the absorption of all three biological domains. The simulated dispersion curves are validated by the results from the commercial software DISPERSE and published literature. Finally, the algorithm is applied to a viscoelastic trilayered TI bone model to interpret the guided modes of an ex-vivo experimental data set from a bone phantom. Copyright © 2017 Elsevier Ltd. All rights reserved.
Okubo, Sho; Iwakuni, Kana; Yamada, Koichi M. T.; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki
2017-11-01
The ν1 +ν3 vibration band of acetylene (C2H2) in the near infrared region was recorded with a dual-comb Fourier-transform spectrometer. We observed 56 transitions from P (26) to R (29) at six different column densities. The integral line intensity was determined for each recorded absorption line by fitting the line profile to Lambert-Beer's law with a Voigt function. Thanks to the outstanding capability of dual-comb spectroscopy to cover a broad spectrum in a relatively short time with high resolution and high frequency precision, we determined the reliable line strength for each ro-vibrational transition as well as the transition dipole moment for this band.
Li, Pan; Zhang, Jianxin; Ma, Shiyu; Jin, Huixin; Zhang, Youjian; Zhang, Wenyang
2018-06-01
The structural, elastic, electronic properties and Debye temperature of Ni3Ta under different pressures are investigated using the first-principles method based on density functional theory. Our calculated equilibrium lattice parameters at 0 GPa well agree with the experimental and previous theoretical results. The calculated negative formation enthalpies and elastic constants both indicate that Ni3Ta is stable under different pressures. The bulk modulus B, shear modulus G, Young's modulus E and Poisson's ratio ν are calculated by the Voigt-Reuss-Hill method. The bigger ratio of B/G indicates Ni3Ta is ductile and the pressure can improve the ductility of Ni3Ta. In addition, the results of density of states and the charge density difference show that the stability of Ni3Ta is improved by the increasing pressure. The Debye temperature ΘD calculated from elastic modulus increases along with the pressure.
Iridium- and Ruthenium-Catalyzed N-alkylation of Amines with Alcohols and Amines
DEFF Research Database (Denmark)
Lorentz-Petersen, Linda Luise Reeh
-helical propensity. Hereby, it was believed that more stable proteins would be obtained. Folding of the mutants was studied in terms of thermodynamics and kinetics by guanidine hydrochloride denaturation monitored by fluorescence. The results were unfortunately unreliable due to errors in the spectrofluorometer....... in the reaction, as ethyleneglycol and 1,2-ethylenediamine failed to produce piperazine. Introduction of a C-substituent on one or both of the starting materials gave Csubstituted piperazines in high yields. Synthesis of N-benzylpiperazine from ethyleneglycol and N-benzylethylenediamine was also successful. Self...... experiments were conducted and emphasized the importance of the Voigt reaction in the formation of the product. Protein folding During an external stay at The Scripps Research Institute, San Diego, California, USA, folding of the well-known protein CI2 was studied. Several mutants were synthetically prepared...
Zhen, Ya-Xin
2017-02-01
In this paper, the transverse wave propagation in fluid-conveying viscoelastic single-walled carbon nanotubes is investigated based on nonlocal elasticity theory with consideration of surface effect. The governing equation is formulated utilizing nonlocal Euler-Bernoulli beam theory and Kelvin-Voigt model. Explicit wave dispersion relation is developed and wave phase velocities and frequencies are obtained. The effect of the fluid flow velocity, structural damping, surface effect, small scale effects and tube diameter on the wave propagation properties are discussed with different wave numbers. The wave frequency increases with the increase of fluid flow velocity, but decreases with the increases of tube diameter and wave number. The effect of surface elasticity and residual surface tension is more significant for small wave number and tube diameter. For larger values of wave number and nonlocal parameters, the real part of frequency ratio raises.
Kochanov, R. V.; Gordon, I. E.; Rothman, L. S.; Wcisło, P.; Hill, C.; Wilzewski, J. S.
2016-07-01
The HITRAN Application Programming Interface (HAPI) is presented. HAPI is a free Python library, which extends the capabilities of the HITRANonline interface (www.hitran.org) and can be used to filter and process the structured spectroscopic data. HAPI incorporates a set of tools for spectra simulation accounting for the temperature, pressure, optical path length, and instrument properties. HAPI is aimed to facilitate the spectroscopic data analysis and the spectra simulation based on the line-by-line data, such as from the HITRAN database [JQSRT (2013) 130, 4-50], allowing the usage of the non-Voigt line profile parameters, custom temperature and pressure dependences, and partition sums. The HAPI functions allow the user to control the spectra simulation and data filtering process via a set of the function parameters. HAPI can be obtained at its homepage www.hitran.org/hapi.
Nanocrystallite characterization of milled simulated dry process fuel powders by neutron diffraction
International Nuclear Information System (INIS)
Ryu, Ho Jin; Kang, Kwon Ho; Moon, Je Sun; Song, Kee Chan; Choi, Yong Nam
2003-01-01
The nano-scale crystallite sizes of simulated spent fuel powders were measured by the neutron diffraction line broadening method in order to analyze the sintering behavior of the dry process fuel. The mixed U0 2 and fission product oxide powders were dry-milled in an attritor for 30, 60, and 120 min. The diffraction patterns of the powders were obtained by using the high resolution powder diffractometer in the HANARO research reactor. Diffraction line broadening due to crystallite size was measured using various techniques such as the Stokes' deconvolution, profile fitting methods using Cauchy function, Gaussian function, and Voigt function, and the Warren-Averbach method. The r.m.s. strain, stacking fault, twin and dislocation density were measured using the information from the diffraction pattern. The realistic crystallite size can be obtained after separation of the contribution from the non-uniform strain, stacking fault and twin
On Palacios-Gordon's theory of relativity
International Nuclear Information System (INIS)
Gulati, P.S.
1981-01-01
Since the early days of Einstein's special theory of relativity (1905), it is known that this theory suffers from some epistemological problems. Over the years, many theoreticians have endeavored to overcome these problems, rejecting either the 'Principle of Relativity' or the 'Light Principle'. Palacios and Gordon rejected the former and advanced an alternative theory governed by Voigt's transformation equations (1887). In the present paper, Palacios-Gordon's theory has been critically examined and some of its drawbacks are discovered. It becomes obvious that neither Einstein's special theory of relativity nor Palacios-Gordon's theory of relativity provides a flawless fit to the real world. It is speculated that suitable synthesis of these two theories might resolve all the controversial issues of special theory of relativity. (author)
Directory of Open Access Journals (Sweden)
Necdet Onur Urs
2016-05-01
Full Text Available Recent developments in the observation of magnetic domains and domain walls by wide-field optical microscopy based on the magneto-optical Kerr, Faraday, Voigt, and Gradient effect are reviewed. Emphasis is given to the existence of higher order magneto-optical effects for advanced magnetic imaging. Fundamental concepts and advances in methodology are discussed that allow for imaging of magnetic domains on various length and time scales. Time-resolved imaging of electric field induced domain wall rotation is shown. Visualization of magnetization dynamics down to picosecond temporal resolution for the imaging of spin-waves and magneto-optical multi-effect domain imaging techniques for obtaining vectorial information are demonstrated. Beyond conventional domain imaging, the use of a magneto-optical indicator technique for local temperature sensing is shown.
Directory of Open Access Journals (Sweden)
Simon Fleming
2011-09-01
Full Text Available Linewidth measurements of a distributed feedback (DFB fibre laser are made using delayed self heterodyne interferometry (DHSI with both Mach-Zehnder and Michelson interferometer configurations. Voigt fitting is used to extract and compare the Lorentzian and Gaussian linewidths and associated sources of noise. The respective measurements are wL (MZI = (1.6 ± 0.2 kHz and wL (MI = (1.4 ± 0.1 kHz. The Michelson with Faraday rotator mirrors gives a slightly narrower linewidth with significantly reduced error. This is explained by the unscrambling of polarisation drift using the Faraday rotator mirrors, confirmed by comparing with non-rotating standard gold coated fibre end mirrors.
Parametric imaging of viscoelasticity using optical coherence elastography
Wijesinghe, Philip; McLaughlin, Robert A.; Sampson, David D.; Kennedy, Brendan F.
2015-03-01
We demonstrate imaging of soft tissue viscoelasticity using optical coherence elastography. Viscoelastic creep deformation is induced in tissue using step-like compressive loading and the resulting time-varying deformation is measured using phase-sensitive optical coherence tomography. From a series of co-located B-scans, we estimate the local strain rate as a function of time, and parameterize it using a four-parameter Kelvin-Voigt model of viscoelastic creep. The estimated viscoelastic strain and time constant are used to visualize viscoelastic creep in 2D, dual-parameter viscoelastograms. We demonstrate our technique on six silicone tissue-simulating phantoms spanning a range of viscoelastic parameters. As an example in soft tissue, we report viscoelastic contrast between muscle and connective tissue in fresh, ex vivo rat gastrocnemius muscle and mouse abdominal transection. Imaging viscoelastic creep deformation has the potential to provide complementary contrast to existing imaging modalities, and may provide greater insight into disease pathology.
Grover, D.; Seth, R. K.
2018-05-01
Analysis and numerical results are presented for the thermoelastic dissipation of a homogeneous isotropic, thermally conducting, Kelvin-Voigt type circular micro-plate based on Kirchhoff's Love plate theory utilizing generalized viscothermoelasticity theory of dual-phase-lagging model. The analytical expressions for thermoelastic damping of vibration and frequency shift are obtained for generalized dual-phase-lagging model and coupled viscothermoelastic plates. The scaled thermoelastic damping has been illustrated in case of circular plate and axisymmetric circular plate for fixed aspect ratio for clamped and simply supported boundary conditions. It is observed that the damping of vibrations significantly depend on time delay and mechanical relaxation times in addition to thermo-mechanical coupling in circular plate under resonance conditions and plate dimensions.
Determination of the elastic constants of portlandite by Brillouin spectroscopy
Speziale, S.; Reichmann, H.J.; Schilling, F.R.; Wenk, H.R.; Monteiro, P.J.M.
2008-01-01
The single crystal elastic constants Cij and the shear and adiabatic bulk modulus of a natural portlandite (Ca(OH)2) crystal were determined by Brillouin spectroscopy at ambient conditions. The elastic constants, expressed in GPa, are: C11 = 102.0(± 2.0), C12 = 32.1(± 1.0), C13 = 8.4(± 0.4), C14 = 4.5(± 0.2), C33 = 33.6(± 0.7), C44 = 12.0(± 0.3), C66 = (C11-C12)/2 = 35.0(± 1.1), where the numbers in parentheses are 1σ standard deviations. The Reuss bounds of the adiabatic bulk and shear moduli are K0S = 26.0(± 0.3) GPa and G0 = 17.5(± 0.4) GPa, respectively, while the Voigt bounds of these moduli are K0S = 37.3(± 0.4) GPa and G0 = 24.4(± 0.3) GPa. The Reuss and Voigt bounds for the aggregate Young's modulus are 42.8(± 1.0) GPa and 60.0(± 0.8) GPa respectively, while the aggregate Poisson's ratio is equal to 0.23(± 0.01). Portlandite exhibits both large compressional elastic anisotropy with C11/C33 = 3.03(± 0.09) equivalent to that of the isostructural hydroxide brucite (Mg(OH)2), and large shear anisotropy with C66/C44 = 2.92(± 0.12) which is 11% larger than brucite. The comparison between the bulk modulus of portlandite and that of lime (CaO) confirms a systematic linear relationship between the bulk moduli of brucite-type simple hydroxides and the corresponding NaCl-type oxides. © 2008 Elsevier Ltd. All rights reserved.
Polarization and pressure effects in caesium 6S-8S two-photon spectroscopy
International Nuclear Information System (INIS)
Lee, Yi-Chi; Tsai, Chin-Chun; Chui, Hsiang-Chen; Chang, Yi-Hsiu; Chen, Ying-Yu
2010-01-01
This work analyses the effects of polarization and pressure in caesium 6S-8S two-photon spectroscopy. The linewidth was broadened and the frequency was shifted by a change of polarization states. The frequency shift and the linewidth broadening of the caesium 6S-8S two-photon transition were measured as a function of laser power using one single-frequency Ti:sapphire ring cavity laser, two caesium cells and two quarter-wave plates to ensure polarization states of light, and we showed that the linewidth cannot be evaluated just by fitting data to a Lorentzian shape. As determined by fitting the data to a Voigt profile, the natural linewidth is independent of the polarization states of the pump beams, the laser power and the pressure. Caesium 6S-8S two-photon transitions pumped by a circularly polarized beam have narrower linewidths and smaller shifts than those pumped by a linearly polarized beam. The light shift obtained by pumping with the circularly polarized beam is -6.75(57) Hz (mW mm -2 ) -1 , and that obtained by pumping with a linearly polarized beam is -7.25(45) Hz (mW mm -2 ) -1 . These results agree closely with theoretical calculations. The pressure shift is -588(387) Hz mPa -1 . This work shows how to evaluate two-photon transitions with a Voigt profile, and then helps us to understand two-photon transitions with different polarization states, and improve the signal quality obtained when they are used as frequency markers.
Directory of Open Access Journals (Sweden)
Luiza G. Ungarova
2016-12-01
Full Text Available We considere and analyze the uniaxial phenomenological models of viscoelastic deformation based on fractional analogues of Scott Blair, Voigt, Maxwell, Kelvin and Zener rheological models. Analytical solutions of the corresponding differential equations are obtained with fractional Riemann–Liouville operators under constant stress with further unloading, that are written by the generalized (two-parameter fractional exponential function and contains from two to four parameters depending on the type of model. A method for identifying the model parameters based on the background information for the experimental creep curves with constant stresses was developed. Nonlinear problem of parametric identification is solved by two-step iterative method. The first stage uses the characteristic data points diagrams and features in the behavior of the models under unrestricted growth of time and the initial approximation of parameters are determined. At the second stage, the refinement of these parameters by coordinate descent (the Hooke–Jeeves's method and minimizing the functional standard deviation for calculated and experimental values is made. Method of identification is realized for all the considered models on the basis of the known experimental data uniaxial viscoelastic deformation of Polyvinylchloride Elastron at a temperature of 20∘C and five the tensile stress levels. Table-valued parameters for all models are given. The errors analysis of constructed phenomenological models is made to experimental data over the entire ensemble of curves viscoelastic deformation. It was found that the approximation errors for the Scott Blair fractional model is 14.17 %, for the Voigt fractional model is 11.13 %, for the Maxvell fractional model is 13.02 %, for the Kelvin fractional model 10.56 %, for the Zener fractional model is 11.06 %. The graphs of the calculated and experimental dependences of viscoelastic deformation of Polyvinylchloride
VizieR Online Data Catalog: Bidelman-Parsons Spectroscopic/Bibliographic Cat (Parsons+ 1980)
Parsons, S. B.; Buta, N. S.; Bidelman, W. P.
1996-11-01
The Bidelman-Parsons Spectroscopic and Bibliographical Catalog (BPSB; Parsons, Buta, and Bidelman 1980a, b) contains data compiled from the astronomical literature by W. P. Bidelman. These data include diverse catalogs and lists, especially from pre-1950 journals (minor as well as major), and from pre-1962 observatory publications. From more recent years, the data on any object frequently are limited to one item with a reference; for example, a spectral type. No data published after 1973 are included. Over 200 publications are represented. The BPSB has information on 40,312 objects. The catalog contains most of the same information on MK spectral types as the Catalogue of Stellar Spectra Classified in the Morgan-Keenan System (Jaschek, Conde, and de Sierra 1964) and its updates, but it also includes such items as spectral types without a luminosity class (certainly better than nothing); spectroscopic absolute magnitudes; notes on multiplicity; notes on high proper motion or radial velocity (with the values, if probably variable, or if greater than 60 km/s); unpublished remarks and spectral types from several sources, including Bidelman and Henize; and Bidelman's preliminary identifications of many sources in the Two-Micron Sky Survey (Neugebauer and Leighton 1969). Some of the longer lists included in the catalog are those of OB stars from the Tonantzintla-Tacubaya and Heidelberg-Koenigstuhl surveys (Iriarte and Chavira 1957; Chavira 1958; Klare and Szeidl 1966); that of OB stars with emission from the Case-Hamburg surveys (Hardorp et al. 1959; Stock, Nassau, and Stephenson 1960; Hardorp, Theile, and Voigt 1964; Nassau and Stephenson 1963; Hardorp, Theile, and Voigt 1965; Nassau, Stephenson, and MacConnell 1965; Stephenson and Sanduleak 1971); and stars from the General Catalogue of Variable Stars (Kukarkin et al. 1969); and the Catalogue of Suspected Variable Stars (Kukarkin et al. 1951, 1965). Although the catalog is mainly of stellar data, it includes many
Rogers, Keir K.; Bird, Simeon; Peiris, Hiranya V.; Pontzen, Andrew; Font-Ribera, Andreu; Leistedt, Boris
2018-05-01
Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (H I; having column densities N(H I) > 1.6 × 10^{17} atoms cm^{-2}), which extend significantly beyond the redshift-space location of the absorber. We measure this effect as a function of the column density of the HCD absorbers and redshift by measuring three-dimensional (3D) flux power spectra in cosmological hydrodynamical simulations from the Illustris project. Survey pipelines exclude regions containing the largest damping wings. We find that, even after this procedure, there is a scale-dependent correction to the 3D Lyman-alpha forest flux power spectrum from residual contamination. We model this residual using a simple physical model of the HCD absorbers as linearly biased tracers of the matter density distribution, convolved with their Voigt profiles and integrated over the column density distribution function. We recommend the use of this model over existing models used in data analysis, which approximate the damping wings as top-hats and so miss shape information in the extended wings. The simple `linear Voigt model' is statistically consistent with our simulation results for a mock residual contamination up to small scales (|k| account for the effect of the highest column density absorbers on the smallest scales (e.g. |k| > 0.4 h Mpc^{-1} for small damped Lyman-alpha absorbers; HCD absorbers with N(H I) ˜ 10^{21} atoms cm^{-2}). However, these systems are in any case preferentially removed from survey data. Our model is appropriate for an accurate analysis of the baryon acoustic oscillations feature. It is additionally essential for reconstructing the full shape of the 3D flux power spectrum.
Asymptotically open quantum systems
International Nuclear Information System (INIS)
Westrich, M.
2008-04-01
In the present thesis we investigate the structure of time-dependent equations of motion in quantum mechanics.We start from two coupled systems with an autonomous equation of motion. A limit, in which the dynamics of one of the two systems has a decoupled evolution and imposes a non-autonomous evolution for the second system is identified. A result due to K. Hepp that provides a classical limit for dynamics turns out to be part and parcel for this limit and is generalized in our work. The method introduced by J.S. Howland for the solution of the time-dependent Schroedinger equation is interpreted as such a limit. Moreover, we associate our limit with the modern theory of quantization. (orig.)
2003-01-01
The C.I.M.E. session on Dynamical Systems, held in Cetraro (Italy), June 19-26, 2000, focused on the latest developments in several important areas in dynamical systems, with full development and historical context. The lectures of Chow and Mallet-Paret focus on the area of lattice differential systems, the lectures of Conto and Galleotti treat the classical problem of classification of orbits for two-dimensional autonomous systems with polynomial right sides, the lectures of Nussbaum focus on applications of fixed point theorems to the problem of limiting profiles for the solutions of singular perturbations of delay differential equations, and the lectures of Johnson and Mantellini deal with the existence of periodic and quasi-periodic orbits to non-autonomous systems. The volume will be of interest to researchers and graduate students working in these areas. .
Signal classification using global dynamical models, Part I: Theory
International Nuclear Information System (INIS)
Kadtke, J.; Kremliovsky, M.
1996-01-01
Detection and classification of signals is one of the principal areas of signal processing, and the utilization of nonlinear information has long been considered as a way of improving performance beyond standard linear (e.g. spectral) techniques. Here, we develop a method for using global models of chaotic dynamical systems theory to define a signal classification processing chain, which is sensitive to nonlinear correlations in the data. We use it to demonstrate classification in high noise regimes (negative SNR), and argue that classification probabilities can be directly computed from ensemble statistics in the model coefficient space. We also develop a modification for non-stationary signals (i.e. transients) using non-autonomous ODEs. In Part II of this paper, we demonstrate the analysis on actual open ocean acoustic data from marine biologics. copyright 1996 American Institute of Physics
International Nuclear Information System (INIS)
Yuan Kun; Cao Jinde
2006-01-01
In this paper, the problems of exponential convergence and the exponential stability of the periodic solution for a general class of non-autonomous competitive-cooperative neural networks are analyzed via the decomposition approach. The idea is to divide the connection weights into inhibitory or excitatory types and thereby to embed a competitive-cooperative delayed neural network into an augmented cooperative delay system through a symmetric transformation. Some simple necessary and sufficient conditions are derived to ensure the componentwise exponential convergence and the exponential stability of the periodic solution of the considered neural networks. These results generalize and improve the previous works, and they are easy to check and apply in practice
Normal form and synchronization of strict-feedback chaotic systems
International Nuclear Information System (INIS)
Wang, Feng; Chen, Shihua; Yu Minghai; Wang Changping
2004-01-01
This study concerns the normal form and synchronization of strict-feedback chaotic systems. We prove that, any strict-feedback chaotic system can be rendered into a normal form with a invertible transform and then a design procedure to synchronize the normal form of a non-autonomous strict-feedback chaotic system is presented. This approach needs only a scalar driving signal to realize synchronization no matter how many dimensions the chaotic system contains. Furthermore, the Roessler chaotic system is taken as a concrete example to illustrate the procedure of designing without transforming a strict-feedback chaotic system into its normal form. Numerical simulations are also provided to show the effectiveness and feasibility of the developed methods
Directory of Open Access Journals (Sweden)
Palle Kiran
2016-03-01
Full Text Available A weak nonlinear oscillatory mode of thermal instability is investigated while deriving a non autonomous complex Ginzburg–Landau equation. Darcy porous medium is considered in the presence of vertical throughflow and time periodic thermal boundaries. Only infinitesimal disturbances are considered. The disturbances in velocity, temperature and solutal fields are treated by a perturbation expansion in powers of amplitude of applied temperature field. The effect of throughflow has either to stabilize or to destabilize the system for stress free and isothermal boundary conditions. Nusselt and Sherwood numbers are obtained numerically and presented the results on heat and mass transfer. It is found that, throughflow and thermal modulation can be used alternatively to control the heat and mass transfer. Further, it is also found that oscillatory flow enhances the heat and mass transfer than stationary flow. Effect of modulation frequency and phase angle on mean Nusselt number is also discussed.
Bhadauria, B. S.; Singh, M. K.; Singh, A.; Singh, B. K.; Kiran, P.
2016-12-01
In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.
Directory of Open Access Journals (Sweden)
Bhadauria B.S.
2016-12-01
Full Text Available In this paper, we investigate the combined effect of internal heating and time periodic gravity modulation in a viscoelastic fluid saturated porous medium by reducing the problem into a complex non-autonomous Ginzgburg-Landau equation. Weak nonlinear stability analysis has been performed by using power series expansion in terms of the amplitude of gravity modulation, which is assumed to be small. The Nusselt number is obtained in terms of the amplitude for oscillatory mode of convection. The influence of viscoelastic parameters on heat transfer has been discussed. Gravity modulation is found to have a destabilizing effect at low frequencies and a stabilizing effect at high frequencies. Finally, it is found that overstability advances the onset of convection, more with internal heating. The conditions for which the complex Ginzgburg-Landau equation undergoes Hopf bifurcation and the amplitude equation undergoes supercritical pitchfork bifurcation are studied.
Durst, Phillip J.; Gray, Wendell; Trentini, Michael
2013-05-01
A simple, quantitative measure for encapsulating the autonomous capabilities of unmanned systems (UMS) has yet to be established. Current models for measuring a UMS's autonomy level require extensive, operational level testing, and provide a means for assessing the autonomy level for a specific mission/task and operational environment. A more elegant technique for quantifying autonomy using component level testing of the robot platform alone, outside of mission and environment contexts, is desirable. Using a high level framework for UMS architectures, such a model for determining a level of autonomy has been developed. The model uses a combination of developmental and component level testing for each aspect of the UMS architecture to define a non-contextual autonomous potential (NCAP). The NCAP provides an autonomy level, ranging from fully non- autonomous to fully autonomous, in the form of a single numeric parameter describing the UMS's performance capabilities when operating at that level of autonomy.
crm-1 facilitates BMP signaling to control body size in Caenorhabditis elegans.
Fung, Wong Yan; Fat, Ko Frankie Chi; Eng, Cheah Kathryn Song; Lau, Chow King
2007-11-01
We have identified in Caenorhabditis elegans a homologue of the vertebrate Crim1, crm-1, which encodes a putative transmembrane protein with multiple cysteine-rich (CR) domains known to have bone morphogenetic proteins (BMPs) binding activity. Using the body morphology of C. elegans as an indicator, we showed that attenuation of crm-1 activity leads to a small body phenotype reminiscent of that of BMP pathway mutants. We showed that the crm-1 loss-of-function phenotype can be rescued by constitutive supply of sma-4 activity. crm-1 can enhance BMP signaling and this activity is dependent on the presence of the DBL-1 ligand and its receptors. crm-1 is expressed in neurons at the ventral nerve cord, where the DBL-1 ligand is produced. However, ectopic expression experiments reveal that crm-1 gene products act outside the DBL-1 producing cells and function non-autonomously to facilitate dbl/sma pathway signaling to control body size.
Dynamics for the complex Ginzburg-Landau equation on non-cylindrical domains II: The monotone case
Zhou, Feng; Sun, Chunyou; Cheng, Jiaqi
2018-02-01
In this article, we continue the study of the dynamics of the following complex Ginzburg-Landau equation ∂tu - (λ + iα)Δu + (κ + iβ)|u|p-2u - γu = f(t) on non-cylindrical domains. We assume that the spatial domains are bounded and increase with time, which is different from the diffeomorphism case presented in Zhou and Sun [Discrete Contin. Dyn. Syst., Ser. B 21, 3767-3792 (2016)]. We develop a new penalty function to establish the existence and uniqueness of a variational solution satisfying energy equality as well as some energy inequalities and prove the existence of a D -pullback attractor for the non-autonomous dynamical system generated by this class of solutions.
Robust permanence for ecological equations with internal and external feedbacks.
Patel, Swati; Schreiber, Sebastian J
2018-07-01
Species experience both internal feedbacks with endogenous factors such as trait evolution and external feedbacks with exogenous factors such as weather. These feedbacks can play an important role in determining whether populations persist or communities of species coexist. To provide a general mathematical framework for studying these effects, we develop a theorem for coexistence for ecological models accounting for internal and external feedbacks. Specifically, we use average Lyapunov functions and Morse decompositions to develop sufficient and necessary conditions for robust permanence, a form of coexistence robust to large perturbations of the population densities and small structural perturbations of the models. We illustrate how our results can be applied to verify permanence in non-autonomous models, structured population models, including those with frequency-dependent feedbacks, and models of eco-evolutionary dynamics. In these applications, we discuss how our results relate to previous results for models with particular types of feedbacks.
Nonlinear dynamics and synchronization of saline oscillator’s model
International Nuclear Information System (INIS)
Fokou Kenfack, W.; Siewe Siewe, M.; Kofane, T.C.
2016-01-01
Highlights: • A model of saline oscillator is derived and tested through numerical simulations. • Interaction between globally coupled saline oscillators is modeled. • Dependence of coupling coefficients on physical parameters is brought out. • Synchronization behaviors are studied using the model equations. - Abstract: The Okamura model equation of saline oscillator is refined into a non-autonomous ordinary differential equation whose coefficients are related to physical parameters of the system. The dependence of the oscillatory period and amplitude on remarkable physical parameters are computed and compared to experimental results in order to test the model. We also model globally coupled saline oscillators and bring out the dependence of coupling coefficients on physical parameters of the system. We then study the synchronization behaviors of coupled saline oscillators by the mean of numerical simulations carried out on the model equations. These simulations agree with previously reported experimental results.
Recombinant SINEs are formed at high frequency during induced retrotransposition in vivo.
Yadav, Vijay Pal; Mandal, Prabhat Kumar; Bhattacharya, Alok; Bhattacharya, Sudha
2012-05-22
Non-long terminal repeat Retrotransposons are referred to as long interspersed nuclear elements (LINEs) and their non-autonomous partners are short interspersed nuclear elements (SINEs). It is believed that an active SINE copy, upon retrotransposition, generates near identical copies of itself, which subsequently accumulate mutations resulting in sequence polymorphism. Here we show that when a retrotransposition-competent cell line of the parasitic protist Entamoeba histolytica, transfected with a marked SINE copy, is induced to retrotranspose, >20% of the newly retrotransposed copies are neither identical to the marked SINE nor to the mobilized resident SINEs. Rather they are recombinants of resident SINEs and the marked SINE. They are a consequence of retrotransposition and not DNA recombination, as they are absent in cells not expressing the retrotransposition functions. This high-frequency recombination provides a new explanation for the existence of mosaic SINEs, which may impact on genetic analysis of SINE lineages, and measurement of phylogenetic distances.
High SINE RNA Expression Correlates with Post-Transcriptional Downregulation of BRCA1
Directory of Open Access Journals (Sweden)
Giovanni Bosco
2013-04-01
Full Text Available Short Interspersed Nuclear Elements (SINEs are non-autonomous retrotransposons that comprise a large fraction of the human genome. SINEs are demethylated in human disease, but whether SINEs become transcriptionally induced and how the resulting transcripts may affect the expression of protein coding genes is unknown. Here, we show that downregulation of the mRNA of the tumor suppressor gene BRCA1 is associated with increased transcription of SINEs and production of sense and antisense SINE small RNAs. We find that BRCA1 mRNA is post-transcriptionally down-regulated in a Dicer and Drosha dependent manner and that expression of a SINE inverted repeat with sequence identity to a BRCA1 intron is sufficient for downregulation of BRCA1 mRNA. These observations suggest that transcriptional activation of SINEs could contribute to a novel mechanism of RNA mediated post-transcriptional silencing of human genes.
On the prolongation structure and Backlund transformation for new non-linear Klein-Gordon equations
International Nuclear Information System (INIS)
Roy Chowdhury, A.; Mukherjee, J.
1986-07-01
We have considered the complete integrability of two nonlinear equations which are some kind of extensions of usual Sine-Gordon and Sinh-Gordon equations. The first one is of non-autonomous version of Sinh-Gordon system and the second is closely related to the usual Sine-Gordon theory. The first problem indicates how (x,t) dependent non-linear equations can be treated in the prolongation theory and how a Backlund map can be constructed. The second one is a variation of the usual Sine-Gordon equation and suggests that there may be other equations (similar to Sine-Gordon) which are completely integrable. In both cases we have been able to construct the Lax pair. We then construct an auto-Backlund map by following the idea of Konno and Wadati, for the generation of multisolution states. (author)
Conserved domains and SINE diversity during animal evolution.
Luchetti, Andrea; Mantovani, Barbara
2013-10-01
Eukaryotic genomes harbour a number of mobile genetic elements (MGEs); moving from one genomic location to another, they are known to impact on the host genome. Short interspersed elements (SINEs) are well-represented, non-autonomous retroelements and they are likely the most diversified MGEs. In some instances, sequence domains conserved across unrelated SINEs have been identified; remarkably, one of these, called Nin, has been conserved since the Radiata-Bilateria splitting. Here we report on two new domains: Inv, derived from Nin, identified in insects and in deuterostomes, and Pln, restricted to polyneopteran insects. The identification of Inv and Pln sequences allowed us to retrieve new SINEs, two in insects and one in a hemichordate. The diverse structural combination of the different domains in different SINE families, during metazoan evolution, offers a clearer view of SINE diversity and their frequent de novo emergence through module exchange, possibly underlying the high evolutionary success of SINEs. © 2013 Elsevier Inc. All rights reserved.
Regularity of random attractors for fractional stochastic reaction-diffusion equations on Rn
Gu, Anhui; Li, Dingshi; Wang, Bixiang; Yang, Han
2018-06-01
We investigate the regularity of random attractors for the non-autonomous non-local fractional stochastic reaction-diffusion equations in Hs (Rn) with s ∈ (0 , 1). We prove the existence and uniqueness of the tempered random attractor that is compact in Hs (Rn) and attracts all tempered random subsets of L2 (Rn) with respect to the norm of Hs (Rn). The main difficulty is to show the pullback asymptotic compactness of solutions in Hs (Rn) due to the noncompactness of Sobolev embeddings on unbounded domains and the almost sure nondifferentiability of the sample paths of the Wiener process. We establish such compactness by the ideas of uniform tail-estimates and the spectral decomposition of solutions in bounded domains.
A self-healable and highly stretchable supercapacitor based on a dual crosslinked polyelectrolyte
Huang, Yan; Zhong, Ming; Huang, Yang; Zhu, Minshen; Pei, Zengxia; Wang, Zifeng; Xue, Qi; Xie, Xuming; Zhi, Chunyi
2015-12-01
Superior self-healability and stretchability are critical elements for the practical wide-scale adoption of personalized electronics such as portable and wearable energy storage devices. However, the low healing efficiency of self-healable supercapacitors and the small strain of stretchable supercapacitors are fundamentally limited by conventional polyvinyl alcohol-based acidic electrolytes, which are intrinsically neither self-healable nor highly stretchable. Here we report an electrolyte comprising polyacrylic acid dual crosslinked by hydrogen bonding and vinyl hybrid silica nanoparticles, which displays all superior functions and provides a solution to the intrinsic self-healability and high stretchability problems of a supercapacitor. Supercapacitors with this electrolyte are non-autonomic self-healable, retaining the capacitance completely even after 20 cycles of breaking/healing. These supercapacitors are stretched up to 600% strain with enhanced performance using a designed facile electrode fabrication procedure.
Biswas, Subhadip; Chattopadhyay, Rohitashwa; Bhattacharjee, Jayanta K.
2018-05-01
We consider the dynamics of a particle in a parametric oscillator with a view to exploring any quantum feature of the initial wave packet that shows divergent (in time) behaviour for parameter values where the classical motion dynamics of the mean position is bounded. We use Ehrenfest's theorem to explore the dynamics of nth order moment which reduces exactly to a linear non autonomous differential equation of order n + 1. It is found that while the width and skewness of the packet is unbounded exactly in the zones where the classical motion is unbounded, the kurtosis of an initially non-gaussian wave packet can become infinitely large in certain additional zones. This implies that the shape of the wave packet can change drastically with time in these zones.
Wilson, Mark A; Iser, Wendy B; Son, Tae Gen; Logie, Anne; Cabral-Costa, Joao V; Mattson, Mark P; Camandola, Simonetta
2017-01-01
Nrf2/skn-1, a transcription factor known to mediate adaptive responses of cells to stress, also regulates energy metabolism in response to changes in nutrient availability. The ability to locate food sources depends upon chemosensation. Here we show that Nrf2/skn-1 is expressed in olfactory interneurons, and is required for proper integration of multiple food-related sensory cues in Caenorhabditis elegans. Compared to wild type worms, skn-1 mutants fail to perceive that food density is limiting, and display altered chemo- and thermotactic responses. These behavioral deficits are associated with aberrant AIY interneuron morphology and migration in skn-1 mutants. Both skn-1-dependent AIY autonomous and non-autonomous mechanisms regulate the neural circuitry underlying multisensory integration of environmental cues related to energy acquisition.
Directory of Open Access Journals (Sweden)
Mark A Wilson
Full Text Available Nrf2/skn-1, a transcription factor known to mediate adaptive responses of cells to stress, also regulates energy metabolism in response to changes in nutrient availability. The ability to locate food sources depends upon chemosensation. Here we show that Nrf2/skn-1 is expressed in olfactory interneurons, and is required for proper integration of multiple food-related sensory cues in Caenorhabditis elegans. Compared to wild type worms, skn-1 mutants fail to perceive that food density is limiting, and display altered chemo- and thermotactic responses. These behavioral deficits are associated with aberrant AIY interneuron morphology and migration in skn-1 mutants. Both skn-1-dependent AIY autonomous and non-autonomous mechanisms regulate the neural circuitry underlying multisensory integration of environmental cues related to energy acquisition.
Sharp conditions for global stability of Lotka-Volterra systems with distributed delays
Faria, Teresa
We give a criterion for the global attractivity of a positive equilibrium of n-dimensional non-autonomous Lotka-Volterra systems with distributed delays. For a class of autonomous Lotka-Volterra systems, we show that such a criterion is sharp, in the sense that it provides necessary and sufficient conditions for the global asymptotic stability independently of the choice of the delay functions. The global attractivity of positive equilibria is established by imposing a diagonal dominance of the instantaneous negative feedback terms, and relies on auxiliary results showing the boundedness of all positive solutions. The paper improves and generalizes known results in the literature, namely by considering systems with distributed delays rather than discrete delays.
The basic approach to age-structured population dynamics models, methods and numerics
Iannelli, Mimmo
2017-01-01
This book provides an introduction to age-structured population modeling which emphasises the connection between mathematical theory and underlying biological assumptions. Through the rigorous development of the linear theory and the nonlinear theory alongside numerics, the authors explore classical equations that describe the dynamics of certain ecological systems. Modeling aspects are discussed to show how relevant problems in the fields of demography, ecology, and epidemiology can be formulated and treated within the theory. In particular, the book presents extensions of age-structured modelling to the spread of diseases and epidemics while also addressing the issue of regularity of solutions, the asymptotic behaviour of solutions, and numerical approximation. With sections on transmission models, non-autonomous models and global dynamics, this book fills a gap in the literature on theoretical population dynamics. The Basic Approach to Age-Structured Population Dynamics will appeal to graduate students an...
A Retrospection of Chaotic Phenomena in Electrical Systems
Directory of Open Access Journals (Sweden)
Umesh Kumar
1998-01-01
Full Text Available In the last decade new phenomena have been observed in all areas of non linear dynamics, principal among these being ‘Chaotic phenomena’. Chaos has been reported virtually from every scientific discipline. This paper summarizes a study of the chaotic phenomena in electrical systems and attempts to translate the mathematical ideas and techniques into language that engineers and applied scientists can use to study ‘Chaos’. Towards this end, the paper has summarized the study of chaos in several examples like Chua’s circuit family; Folded Torus circuit; non-autonomous circuits; switched capacitor circuits and hyper-chaos circuits. As observed in power systems, control systems and digital filters, chaos has been exhibited and shown on examples.
Articulated pipes conveying fluid pulsating with high frequency
DEFF Research Database (Denmark)
Jensen, Jakob Søndergaard
1999-01-01
Stability and nonlinear dynamics of two articulated pipes conveying fluid with a high-frequency pulsating component is investigated. The non-autonomous model equations are converted into autonomous equations by approximating the fast excitation terms with slowly varying terms. The downward hanging...... pipe position will lose stability if the mean flow speed exceeds a certain critical value. Adding a pulsating component to the fluid flow is shown to stabilize the hanging position for high values of the ratio between fluid and pipe-mass, and to marginally destabilize this position for low ratios....... An approximate nonlinear solution for small-amplitude flutter oscillations is obtained using a fifth-order multiple scales perturbation method, and large-amplitude oscillations are examined by numerical integration of the autonomous model equations, using a path-following algorithm. The pulsating fluid component...
Topological structure of the solution set for evolution inclusions
Zhou, Yong; Peng, Li
2017-01-01
This book systematically presents the topological structure of solution sets and attractability for nonlinear evolution inclusions, together with its relevant applications in control problems and partial differential equations. It provides readers the background material needed to delve deeper into the subject and explore the rich research literature. In addition, the book addresses many of the basic techniques and results recently developed in connection with this theory, including the structure of solution sets for evolution inclusions with m-dissipative operators; quasi-autonomous and non-autonomous evolution inclusions and control systems;evolution inclusions with the Hille-Yosida operator; functional evolution inclusions; impulsive evolution inclusions; and stochastic evolution inclusions. Several applications of evolution inclusions and control systems are also discussed in detail. Based on extensive research work conducted by the authors and other experts over the past four years, the information p...
Quasi-periodic dynamics in system with multilevel pulse modulated control
Gol'tsov, Yu A.; Kizhuk, A. S.; Rubanov, V. G.
2018-03-01
In this paper, the authors describe the transitions from the regular periodic mode to quasiperiodicity that can be observed in a multilevel pulse-width modulated control system for a high-power heating unit. The behavior of such system can be described by a set of two coupled non-autonomous differential equations with discontinuous right-hand sides. The authors reduce the investigation of this system to the studying of a two-dimensional piecewise-smooth map. The authors demonstrate how a closed invariant curve associated with quasiperiodic dynamics can arise from a stable periodic motion through a border-collision bifurcation. The paper also considers a variety of interesting nonlinear phenomena, including phase-locking modes, the coexistence of several stable closed invariant curves, embedded one into the other and with their basins of attraction separated by intervening repelling closed curves.
Asymptotically open quantum systems; Asymptotisch offene Quantensysteme
Energy Technology Data Exchange (ETDEWEB)
Westrich, M.
2008-04-15
In the present thesis we investigate the structure of time-dependent equations of motion in quantum mechanics.We start from two coupled systems with an autonomous equation of motion. A limit, in which the dynamics of one of the two systems has a decoupled evolution and imposes a non-autonomous evolution for the second system is identified. A result due to K. Hepp that provides a classical limit for dynamics turns out to be part and parcel for this limit and is generalized in our work. The method introduced by J.S. Howland for the solution of the time-dependent Schroedinger equation is interpreted as such a limit. Moreover, we associate our limit with the modern theory of quantization. (orig.)
Kugler, Josephine; Luch, Andreas; Oelgeschläger, Michael
2016-10-01
Despite our increasing understanding of molecular mechanisms controlling embryogenesis, the identification and characterization of teratogenic substances still heavily relies on animal testing. Embryonic development depends on cell-autonomous and non-autonomous processes including spatiotemporally regulated extracellular signaling activities. These have been elucidated in transgenic mouse models harboring easily detectable reporter genes under the control of evolutionarily conserved signaling cascades. We propose combining these transgenic mouse models and cells derived thereof with existing alternative toxicological testing strategies. This would enable the plausibility of in vitro data to be verified in light of in vivo data and, ultimately, facilitate regulatory acceptance of in vitro test methods. Copyright © 2016 Elsevier Ltd. All rights reserved.
Frilot, Clifton; Kim, Paul Y.; Carrubba, Simona; McCarty, David E.; Chesson, Andrew L.; Marino, Andrew A.
Analysis of Brain Recurrence (ABR) is a method for extracting physiologically significant information from the electroencephalogram (EEG), a non-stationary electrical output of the brain, the ultimate complex dynamical system. ABR permits quantification of temporal patterns in the EEG produced by the non-autonomous differential laws that govern brain metabolism. In the context of appropriate experimental and statistical designs, ABR is ideally suited to the task of interpreting the EEG. Present applications of ABR include discovery of a human magnetic sense, increased mechanistic understanding of neuronal membrane processes, diagnosis of degenerative neurological disease, detection of changes in brain metabolism caused by weak environmental electromagnetic fields, objective characterization of the quality of human sleep, and evaluation of sleep disorders. ABR has important beneficial implications for the development of clinical and experimental neuroscience.
PT-symmetry management in oligomer systems
International Nuclear Information System (INIS)
Horne, R L; Cuevas, J; Kevrekidis, P G; Whitaker, N; Abdullaev, F Kh; Frantzeskakis, D J
2013-01-01
We study the effects of management of the PT-symmetric part of the potential within the setting of Schrödinger dimer and trimer oligomer systems. This is done by rapidly modulating in time the gain/loss profile. This gives rise to a number of interesting properties of the system, which are explored at the level of an averaged equation approach. Remarkably, this rapid modulation provides for a controllable expansion of the region of exact PT-symmetry, depending on the strength and frequency of the imposed modulation. The resulting averaged models are analysed theoretically and their exact stationary solutions are translated into time-periodic solutions through the averaging reduction. These are, in turn, compared with the exact periodic solutions of the full non-autonomous PT-symmetry managed problem and very good agreement is found between the two. (paper)
Neurons other than motor neurons in motor neuron disease.
Ruffoli, Riccardo; Biagioni, Francesca; Busceti, Carla L; Gaglione, Anderson; Ryskalin, Larisa; Gambardella, Stefano; Frati, Alessandro; Fornai, Francesco
2017-11-01
Amyotrophic lateral sclerosis (ALS) is typically defined by a loss of motor neurons in the central nervous system. Accordingly, morphological analysis for decades considered motor neurons (in the cortex, brainstem and spinal cord) as the neuronal population selectively involved in ALS. Similarly, this was considered the pathological marker to score disease severity ex vivo both in patients and experimental models. However, the concept of non-autonomous motor neuron death was used recently to indicate the need for additional cell types to produce motor neuron death in ALS. This means that motor neuron loss occurs only when they are connected with other cell types. This concept originally emphasized the need for resident glia as well as non-resident inflammatory cells. Nowadays, the additional role of neurons other than motor neurons emerged in the scenario to induce non-autonomous motor neuron death. In fact, in ALS neurons diverse from motor neurons are involved. These cells play multiple roles in ALS: (i) they participate in the chain of events to produce motor neuron loss; (ii) they may even degenerate more than and before motor neurons. In the present manuscript evidence about multi-neuronal involvement in ALS patients and experimental models is discussed. Specific sub-classes of neurons in the whole spinal cord are reported either to degenerate or to trigger neuronal degeneration, thus portraying ALS as a whole spinal cord disorder rather than a disease affecting motor neurons solely. This is associated with a novel concept in motor neuron disease which recruits abnormal mechanisms of cell to cell communication.
Characterization and Diversity of Novel PIF/Harbinger DNA Transposons in Brassica Genomes
International Nuclear Information System (INIS)
Nouroz, F.; Noreen, S.; Harrison, H.
2016-01-01
Among DNA transposons, PIF/Harbinger is most recently identified superfamily characterized by 3 bp target site duplications (TSDs), flanked by 14-45 bp terminal inverted repeats (TIRs) and displaying DDD or DDE domain displaying transposase. Their autonomous elements contain two open reading frames, ORF1 and ORF2 encoding superfamily specific transposase and DNA-binding domain. Harbinger DNA transposons are recently identified in few plants. In present study, computational and molecular approaches were used for the identification of 8 Harbinger transposons, of which only 2 were complete with putative trans posase, while rest 6 lack transposase and are considered as defective or non-autonomous elements. They ranged in size from 0.5-4 kb with 3 bp TSDs, 15-42 bp TIRs and internal AT richregions. The PCR amplification of Brassica Harbinger transposase revealed diversity and ancient nature of these elements. The amplification polymorphism of some non-autonomous Harbingers showed species specific distribution. Phylogenetic analyses of transposase clustered them into two clades (monocot and dicot) and five sub-clades. The Brassica, Arabidopsis and Malustransposase clustered into genera specific sub-clades; although a lot of homology in transposase was observed. The multiple sequence alignment of Brassica and related transposase showed homology in five conserved blocks. The DD/Sub 35/E triad and sequences showed similarity to already known Pong-like or Arabidopsis ATIS12 Harbinger transposase in contrast to other transposase having DD/Sub 47/E or DD/Sub 48/E motifs. The present study will be helpful in the characterization of Harbingers, their structural diversity in related genera and Harbinger based molecular markers for varietal/lines identifications. (author)
Effect of periodic environmental fluctuations on the Pearl-Verhulst model
International Nuclear Information System (INIS)
Rogovchenko, Svitlana P.; Rogovchenko, Yuri V.
2009-01-01
We address the effect of periodic environmental fluctuations on the Pearl-Verhulst model in population dynamics and clarify several important issues very actively discussed in the recent papers by Lakshmi [Lakshmi BS. Oscillating population models. Chaos Solitons and Fractals 2003;16:183-6; Lakshmi BS. Population models with time dependent parameters. Chaos Solitons and Fractals 2005;26:719-21], Leach and Andriopoulos [Leach PGL, Andriopoulos K. An oscillatory population model. Chaos Solitons and Fractals 2004;22:1183-8], Swart and Murrell [Swart JH, Murrell HC. An oscillatory model revisited. Chaos Solitons and Fractals 2007;32:1325-7]. Firstly, we review general results regarding existence and properties of periodic solutions and examine existence of a unique positive asymptotically stable periodic solution of a non-autonomous logistic differential equation when r(t)>0. Proceeding to the case where r(t) is allowed to take on negative values, we consider a modified Pearl-Verhulst equation because, as emphasized by Hallam and Clark [Hallam TG, Clark CE. Non-autonomous logistic equations as models of populations in deteriorating environment. J Theor Biol 1981;93:303-11], use of the classic one leads to paradoxical biological conclusions. For a modified logistic equation with ω-periodic coefficients, we establish existence of a unique asymptotically stable positive periodic solution with the same period. Special attention is paid to important cases where time average of the intrinsic growth rate is non-positive. Results of computer simulation demonstrating advantages of a modified equation for modeling periodic environmental fluctuations are presented.
Valdes Franco, José A; Wang, Yi; Huo, Naxin; Ponciano, Grisel; Colvin, Howard A; McMahan, Colleen M; Gu, Yong Q; Belknap, William R
2018-04-19
Guayule (Parthenium argentatum A. Gray) is a rubber-producing desert shrub native to Mexico and the United States. Guayule represents an alternative to Hevea brasiliensis as a source for commercial natural rubber. The efficient application of modern molecular/genetic tools to guayule improvement requires characterization of its genome. The 1.6 Gb guayule genome was sequenced, assembled and annotated. The final 1.5 Gb assembly, while fragmented (N 50 = 22 kb), maps > 95% of the shotgun reads and is essentially complete. Approximately 40,000 transcribed, protein encoding genes were annotated on the assembly. Further characterization of this genome revealed 15 families of small, microsatellite-associated, transposable elements (TEs) with unexpected chromosomal distribution profiles. These SaTar (Satellite Targeted) elements, which are non-autonomous Mu-like elements (MULEs), were frequently observed in multimeric linear arrays of unrelated individual elements within which no individual element is interrupted by another. This uniformly non-nested TE multimer architecture has not been previously described in either eukaryotic or prokaryotic genomes. Five families of similarly distributed non-autonomous MULEs (microsatellite associated, modularly assembled) were characterized in the rice genome. Families of TEs with similar structures and distribution profiles were identified in sorghum and citrus. The sequencing and assembly of the guayule genome provides a foundation for application of current crop improvement technologies to this plant. In addition, characterization of this genome revealed SaTar elements with distribution profiles unique among TEs. Satar targeting appears based on an alternative MULE recombination mechanism with the potential to impact gene evolution.
Electrical characteristics of the hydroxyapatite for biomedical applications
International Nuclear Information System (INIS)
Lopez Buisan N, M.G.; Mendez G, M.M.
2006-01-01
The electric characteristics of hydroxyapatite films were studied (HAP) deposited on metallic substrates oxidized naturally. The substrates was made of steel 316L and of titanium. These materials are used in reconstructive surgery for prosthesis and osseous implants. The studies were carried out with the techniques of potentiostatic polarization and faraday impedance. The potentiostatic polarization reveals that the very well-known piezoelectricity of the HAp subsists after the coating processes (it captures thermal and spray-pyrolysis). Its also revealed a semiconductor behavior of the HAp that until now had not been reported. This characteristic is important, by its relationship with the stability of the HAp coating in front of corrosion processes in the alive tissues. The results of the impedance tests were mathematically analyzed starting from the Nyquist diagrams, of Bode and of power. The physical interpretation is presented under the form of equivalent circuits (CE). In the case of the HAp on a steel 316L substrate, the CE is a Rancles-Voigt module that corresponds to the behavior of a dielectric with flights. In the case of the titanium substrate an element of constant phase appears to high frequencies (CPE), in series with the Rancles-Voigt module. The CPE reveals the presence of a rectifier of the metal/SC-n type that only it could be located in the interface among the titanium and its natural oxide (TiO 2 ). The absence of the CPE in the case of the steel 316L substrate indicates that the natural oxide (Cr 2 O 3 ) it doesn't form with the steel a Schottky diode, possibly because the chromite is as a SC-n degenerate. On the interface Ti/TiO 2 exists results qualitatively identical by other researchers that have worked with the same impedance technique, but applied by humid via (EIS). The CE that have proposed are based on the anodic processes of accretion/dissolution of the film at low pH. This proposal is questioned by our results, obtained under non
Energy Technology Data Exchange (ETDEWEB)
Lopez Buisan N, M.G.; Mendez G, M.M. [Laboratorio de Corrosion, ESFM-IPN, 07738 Mexico D.F. (Mexico)
2006-07-01
The electric characteristics of hydroxyapatite films were studied (HAP) deposited on metallic substrates oxidized naturally. The substrates was made of steel 316L and of titanium. These materials are used in reconstructive surgery for prosthesis and osseous implants. The studies were carried out with the techniques of potentiostatic polarization and faraday impedance. The potentiostatic polarization reveals that the very well-known piezoelectricity of the HAp subsists after the coating processes (it captures thermal and spray-pyrolysis). Its also revealed a semiconductor behavior of the HAp that until now had not been reported. This characteristic is important, by its relationship with the stability of the HAp coating in front of corrosion processes in the alive tissues. The results of the impedance tests were mathematically analyzed starting from the Nyquist diagrams, of Bode and of power. The physical interpretation is presented under the form of equivalent circuits (CE). In the case of the HAp on a steel 316L substrate, the CE is a Rancles-Voigt module that corresponds to the behavior of a dielectric with flights. In the case of the titanium substrate an element of constant phase appears to high frequencies (CPE), in series with the Rancles-Voigt module. The CPE reveals the presence of a rectifier of the metal/SC-n type that only it could be located in the interface among the titanium and its natural oxide (TiO{sub 2}). The absence of the CPE in the case of the steel 316L substrate indicates that the natural oxide (Cr{sub 2}O{sub 3}) it doesn't form with the steel a Schottky diode, possibly because the chromite is as a SC-n degenerate. On the interface Ti/TiO{sub 2} exists results qualitatively identical by other researchers that have worked with the same impedance technique, but applied by humid via (EIS). The CE that have proposed are based on the anodic processes of accretion/dissolution of the film at low pH. This proposal is questioned by our results
CONSTRUCTION OF MECHANICAL MODEL OF THE DIESEL-TRAIN DTKR-2 CAR AND ITS FEATURES
Directory of Open Access Journals (Sweden)
A. Y. Kuzyshyn
2017-12-01
Full Text Available Purpose.The article is aimed to construct the mechanical model of the diesel train DTKr-2 of the Kryukivsk Railway Car Building Works based on the analysis of undercarriage construction. This model will be used in the study of dynamic properties of the vehicle. When constructing the model the design features and its loading methods should be displayed as much as possible. Methodology. When constructing the mechanical model of the diesel train DTKr-2 car, the pneumatic spring, which is the main element of the central spring suspension, was modeled using Kelvin-Voigt node. This node includes elastic and viscous element. Hydraulic shock absorbers that are used both in the central and axle-box spring suspension were modeled as a viscous element. During research, the rigidity of the pneumatic spring, which is associated with the change in its effective area under deformation, was assumed to be zero. Findings. This article analyzed the design of car undercarriage of the diesel train DTKr-2. The mathematical models of its main units were presented, namely, in the central spring suspension – the model of pneumatic spring. Taking into account the peculiarities of design of the diesel train DTKr-2 undercarriage it was developed its mechanical model, which will be used in the future when studying dynamic properties. Originality.For the first time for the diesel train DTKr-2 car it was developed its mechanical model taking into account the features of the interaction of individual elements of its design. It has been proposed as a pneumatic spring to use the Kelvin-Voigt node, which includes parallel arranged elastic and viscous elements. Practical value. On the basis of the proposed mechanical model, a system of ordinary differential equations of car undercarriage movement of the diesel train DTKr-2 (mathematical model will be compiled. This model is further planned to be used when studying dynamic interaction of the diesel train car undercarriage wheel
Determination of the elastic constants of portlandite by Brillouin spectroscopy
Speziale, S.
2008-10-01
The single crystal elastic constants Cij and the shear and adiabatic bulk modulus of a natural portlandite (Ca(OH)2) crystal were determined by Brillouin spectroscopy at ambient conditions. The elastic constants, expressed in GPa, are: C11 = 102.0(± 2.0), C12 = 32.1(± 1.0), C13 = 8.4(± 0.4), C14 = 4.5(± 0.2), C33 = 33.6(± 0.7), C44 = 12.0(± 0.3), C66 = (C11-C12)/2 = 35.0(± 1.1), where the numbers in parentheses are 1σ standard deviations. The Reuss bounds of the adiabatic bulk and shear moduli are K0S = 26.0(± 0.3) GPa and G0 = 17.5(± 0.4) GPa, respectively, while the Voigt bounds of these moduli are K0S = 37.3(± 0.4) GPa and G0 = 24.4(± 0.3) GPa. The Reuss and Voigt bounds for the aggregate Young\\'s modulus are 42.8(± 1.0) GPa and 60.0(± 0.8) GPa respectively, while the aggregate Poisson\\'s ratio is equal to 0.23(± 0.01). Portlandite exhibits both large compressional elastic anisotropy with C11/C33 = 3.03(± 0.09) equivalent to that of the isostructural hydroxide brucite (Mg(OH)2), and large shear anisotropy with C66/C44 = 2.92(± 0.12) which is 11% larger than brucite. The comparison between the bulk modulus of portlandite and that of lime (CaO) confirms a systematic linear relationship between the bulk moduli of brucite-type simple hydroxides and the corresponding NaCl-type oxides. © 2008 Elsevier Ltd. All rights reserved.
A New GPU-Enabled MODTRAN Thermal Model for the PLUME TRACKER Volcanic Emission Analysis Toolkit
Acharya, P. K.; Berk, A.; Guiang, C.; Kennett, R.; Perkins, T.; Realmuto, V. J.
2013-12-01
Real-time quantification of volcanic gaseous and particulate releases is important for (1) recognizing rapid increases in SO2 gaseous emissions which may signal an impending eruption; (2) characterizing ash clouds to enable safe and efficient commercial aviation; and (3) quantifying the impact of volcanic aerosols on climate forcing. The Jet Propulsion Laboratory (JPL) has developed state-of-the-art algorithms, embedded in their analyst-driven Plume Tracker toolkit, for performing SO2, NH3, and CH4 retrievals from remotely sensed multi-spectral Thermal InfraRed spectral imagery. While Plume Tracker provides accurate results, it typically requires extensive analyst time. A major bottleneck in this processing is the relatively slow but accurate FORTRAN-based MODTRAN atmospheric and plume radiance model, developed by Spectral Sciences, Inc. (SSI). To overcome this bottleneck, SSI in collaboration with JPL, is porting these slow thermal radiance algorithms onto massively parallel, relatively inexpensive and commercially-available GPUs. This paper discusses SSI's efforts to accelerate the MODTRAN thermal emission algorithms used by Plume Tracker. Specifically, we are developing a GPU implementation of the Curtis-Godson averaging and the Voigt in-band transmittances from near line center molecular absorption, which comprise the major computational bottleneck. The transmittance calculations were decomposed into separate functions, individually implemented as GPU kernels, and tested for accuracy and performance relative to the original CPU code. Speedup factors of 14 to 30× were realized for individual processing components on an NVIDIA GeForce GTX 295 graphics card with no loss of accuracy. Due to the separate host (CPU) and device (GPU) memory spaces, a redesign of the MODTRAN architecture was required to ensure efficient data transfer between host and device, and to facilitate high parallel throughput. Currently, we are incorporating the separate GPU kernels into a
Rietveld analysis and electronic bands structure on Tc superconductors systems
International Nuclear Information System (INIS)
Aldea, N.; Tiusan, C. V.; Sandu, V.
1999-01-01
A procedure for simultaneous refinement of structural and micro-structural disorder parameters for polycrystalline YBa 2 Cu 3 O 7-x system is proposed. It is based on Rietveld method combined with Fourier analysis for broadened peaks Another purpose of this paper consists in electronic structure determination studied by using the self-consistent Tight Binding Linear Muffin-Tin Orbital Atomic Spheres Approximation TB-LMTO-ASA methods. The Rietveld method uses an analytical function that describes the profiles, usually pseudo-Voigt (pV) or Pearson VII (PVII). The parameters of the analytical profiles describe its amplitude, position and peak shape. The full width at half maximum (FWHM) is supposed to vary with the diffraction angle in agreement with the Caglioti, Paoletti and Ricci's relationship. The best structural parameters are determined in the least squares sense by the minimisation a classical residual using the Marquardt method. In this case, the peak profiles were modelled by the pseudo-Voigt function corrected by the instrumental asymmetry. The physical information obtained are: scale factor, lattice parameters, atomic position and displacements, atomic occupation numbers, temperature factor (isotropy or anisotropy), preferred orientation parameter, crystalline size and micro-strain along different crystallographic directions, distributions of crystallite size and micro-strain functions. This procedure was implemented on computer code and it has a friendly graphical interface based on pull down menus technique. From the experimental point of view the X-ray diffraction data were collected using a horizontal powder diffractometer in the Bragg-Brentano (BB) geometry with a Ni filtered CuKα, λ = 1.54178 A, at room temperature using a DRON 2 set-up. The diffraction profiles were measured with a proportional gas detector, a single channel pulse-height discrimination and a standard associated counting circuit. The electronic band calculations are based on the TB
Rannou, Pascal; Seignovert, Benoit; Le Mouélic, Stéphane; Sotin, Christophe
2016-10-01
The study of Titan properties with remote sensing relies on a good knowledge of the atmosphere properties. The in-situ observations made by Huygens combined with recent advances in the definition of methane properties enable to model and interpret observations with a very good accuracy. Thanks to these progresses, we can analyze in this work the observations made at the limb of Titan in order to retrieve information on the haze properties as its vertical profiles and its spectral behaviour along the VIMS/Cassini range (from 0.88 to 5.1 μm). However, for applications to real atmospheres, one need to account for the widening of the spectroscopic lines (e.g., Voigt profile) and apply an empirical cut-off of the far wings. In general, this is a multiplying function of the wavenumber, f(ν), applied to the Voigt profile that allows a faster decay of the wing profile beyond a given distance from the center of the line ν0 : f(ν)=1 if |ν- ν0| ≤ Δν, and f(ν)=exp(-|ν- ν0|/ σ) if |ν- ν0| > Δν. Although the 2-μm window is apparently straitforward to model, it appears that the standard cut-off parameters (that is Δν ~ 26 cm-1 and σ ~ 120 cm-1) which is used for other windows in Titan's atmosphere is not adequat for this window. Other sets of parameter must be used to reproduce Titan spectrum at 2 μm. However, there is no convergence of the results between these works and a large variety of cut-off parameters are used. Alternatively, it was found that some gas absorptions (ethane and another unknown gas) leave a signature around 2-μm and also affect the transparency in this window. In our study we make an exhaustive investigation on the cut-off parameters to determine which are the best couples of parameters to fit the 2-μm window. We also evaluated how gaseous absorptions can allow to reach a satisfactory agreement and, especially, if it allows to match observations with the standard cut-off. Finally, we investigate the impact of the different solutions
Theory of electromagnetic wave propagation in ferromagnetic Rashba conductor
Shibata, Junya; Takeuchi, Akihito; Kohno, Hiroshi; Tatara, Gen
2018-02-01
We present a comprehensive study of various electromagnetic wave propagation phenomena in a ferromagnetic bulk Rashba conductor from the perspective of quantum mechanical transport. In this system, both the space inversion and time reversal symmetries are broken, as characterized by the Rashba field α and magnetization M, respectively. First, we present a general phenomenological analysis of electromagnetic wave propagation in media with broken space inversion and time reversal symmetries based on the dielectric tensor. The dependence of the dielectric tensor on the wave vector q and M is retained to first order. Then, we calculate the microscopic electromagnetic response of the current and spin of conduction electrons subjected to α and M, based on linear response theory and the Green's function method; the results are used to study the system optical properties. First, it is found that a large α enhances the anisotropic properties of the system and enlarges the frequency range in which the electromagnetic waves have hyperbolic dispersion surfaces and exhibit unusual propagations known as negative refraction and backward waves. Second, we consider the electromagnetic cross-correlation effects (direct and inverse Edelstein effects) on the wave propagation. These effects stem from the lack of space inversion symmetry and yield q-linear off-diagonal components in the dielectric tensor. This induces a Rashba-induced birefringence, in which the polarization vector rotates around the vector (α ×q ) . In the presence of M, which breaks time reversal symmetry, there arises an anomalous Hall effect and the dielectric tensor acquires off-diagonal components linear in M. For α ∥M , these components yield the Faraday effect for the Faraday configuration q ∥M and the Cotton-Mouton effect for the Voigt configuration ( q ⊥M ). When α and M are noncollinear, M- and q-induced optical phenomena are possible, which include nonreciprocal directional dichroism in the
Fully Digital Chaotic Oscillators Applied to Pseudo Random Number Generation
Mansingka, Abhinav S.
2012-05-01
This thesis presents a generalized approach for the fully digital design and implementation of chaos generators through the numerical solution of chaotic ordinary differential equations. In particular, implementations use the Euler approximation with a fixed-point twos complement number representation system for optimal hardware and performance. In general, digital design enables significant benefits in terms of power, area, throughput, reliability, repeatability and portability over analog implementations of chaos due to lower process, voltage and temperature sensitivities and easy compatibility with other digital systems such as microprocessors, digital signal processing units, communication systems and encryption systems. Furthermore, this thesis introduces the idea of implementing multidimensional chaotic systems rather than 1-D chaotic maps to enable wider throughputs and multiplier-free architectures that provide significant performance and area benefits. This work focuses efforts on the well-understood family of autonomous 3rd order "jerk" chaotic systems. The effect of implementation precision, internal delay cycles and external delay cycles on the chaotic response are assessed. Multiplexing of parameters is implemented to enable switching between chaotic and periodic modes of operation. Enhanced chaos generators that exploit long-term divergence in two identical systems of different precision are also explored. Digital design is shown to enable real-time controllability of 1D multiscroll systems and 4th order hyperchaotic systems, essentially creating non-autonomous chaos that has thus far been difficult to implement in the analog domain. Seven different systems are mathematically assessed for chaotic properties, implemented at the register transfer level in Verilog HDL and experimentally verified on a Xilinx Virtex 4 FPGA. The statistical properties of the output are rigorously studied using the NIST SP. 800-22 statistical testing suite. The output is
Mariner transposons are sailing in the genome of the blood-sucking bug Rhodnius prolixus.
Filée, Jonathan; Rouault, Jacques-Deric; Harry, Myriam; Hua-Van, Aurélie
2015-12-15
The Triatomine bug Rhodnius prolixus is a vector of Trypanosoma cruzi, which causes the Chagas disease in Latin America. R. prolixus can also transfer transposable elements horizontally across a wide range of species. We have taken advantage of the availability of the 700 Mbp complete genome sequence of R. prolixus to study the dynamics of invasion and persistence of transposable elements in this species. Using both library-based and de novo methods of transposon detection, we found less than 6 % of transposable elements in the R. prolixus genome, a relatively low percentage compared to other insect genomes with a similar genome size. DNA transposons are surprisingly abundant and elements belonging to the mariner family are by far the most preponderant components of the mobile part of this genome with 11,015 mariner transposons that could be clustered in 89 groups (75 % of the mobilome). Our analysis allowed the detection of a new mariner clade in the R. prolixus genome, that we called nosferatis. We demonstrated that a large diversity of mariner elements invaded the genome and expanded successfully over time via three main processes. (i) several families experienced recent and massive expansion, for example an explosive burst of a single mariner family led to the generation of more than 8000 copies. These recent expansion events explain the unusual prevalence of mariner transposons in the R. prolixus genome. Other families expanded via older bursts of transposition demonstrating the long lasting permissibility of mariner transposons in the R. prolixus genome. (ii) Many non-autonomous families generated by internal deletions were also identified. Interestingly, two non autonomous families were generated by atypical recombinations (5' part replacement with 3' part). (iii) at least 10 cases of horizontal transfers were found, supporting the idea that host/vector relationships played a pivotal role in the transmission and subsequent persistence of transposable
Can we identify non-stationary dynamics of trial-to-trial variability?
Directory of Open Access Journals (Sweden)
Emili Balaguer-Ballester
Full Text Available Identifying sources of the apparent variability in non-stationary scenarios is a fundamental problem in many biological data analysis settings. For instance, neurophysiological responses to the same task often vary from each repetition of the same experiment (trial to the next. The origin and functional role of this observed variability is one of the fundamental questions in neuroscience. The nature of such trial-to-trial dynamics however remains largely elusive to current data analysis approaches. A range of strategies have been proposed in modalities such as electro-encephalography but gaining a fundamental insight into latent sources of trial-to-trial variability in neural recordings is still a major challenge. In this paper, we present a proof-of-concept study to the analysis of trial-to-trial variability dynamics founded on non-autonomous dynamical systems. At this initial stage, we evaluate the capacity of a simple statistic based on the behaviour of trajectories in classification settings, the trajectory coherence, in order to identify trial-to-trial dynamics. First, we derive the conditions leading to observable changes in datasets generated by a compact dynamical system (the Duffing equation. This canonical system plays the role of a ubiquitous model of non-stationary supervised classification problems. Second, we estimate the coherence of class-trajectories in empirically reconstructed space of system states. We show how this analysis can discern variations attributable to non-autonomous deterministic processes from stochastic fluctuations. The analyses are benchmarked using simulated and two different real datasets which have been shown to exhibit attractor dynamics. As an illustrative example, we focused on the analysis of the rat's frontal cortex ensemble dynamics during a decision-making task. Results suggest that, in line with recent hypotheses, rather than internal noise, it is the deterministic trend which most likely underlies
Energy Technology Data Exchange (ETDEWEB)
Ponce, C A [Departamento de Fisica, Facultad de Ciencias Exactas, y Naturales y Agrimensura, UNNE, Campus Universitario, Avenida Libertad 5600, CP 3400, Corrientes (Argentina); Casali, R A [Departamento de Fisica, Facultad de Ciencias Exactas, y Naturales y Agrimensura, UNNE, Campus Universitario, Avenida Libertad 5600, CP 3400, Corrientes (Argentina); Caravaca, M A [Departamento de Fisico, Quimica, Facultad de Ingenieria, UNNE, Avenida Las Heras 727, CP 3500, Resistencia (Argentina)
2008-01-30
By means of the ab initio all-electron new full-potential linear-muffin-tin orbitals method, calculations were made for elastic constants C{sub 11}, C{sub 12} and C{sub 44} for Si, ZrO{sub 2} and HfO{sub 2} in their cubic phase, and constants C{sub 11}, C{sub 22}, C{sub 33}, C{sub 12}, C{sub 13}, C{sub 23}, C{sub 44}, C{sub 55} and C{sub 66} for HfO{sub 2} in its orthorhombic phase. Using the Voigt and Reuss theory, estimations were made for polycrystals of their bulk, shear and Young moduli, and Poisson coefficients. The speed of elastic wave propagations and Debye temperatures were estimated for polycrystals built from Si and the above mentioned compounds. The semicore 4f{sup 14} electrons should be included in the valence set of Hf atom in this all-electron approach if accurate results for elastic properties under pressures are looked for.
Schreier, Franz; Gimeno García, Sebastián; Hedelt, Pascal; Hess, Michael; Mendrok, Jana; Vasquez, Mayte; Xu, Jian
2014-04-01
A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code - GARLIC - is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus.
International Nuclear Information System (INIS)
Soltani, P; Farshidianfar, A; Taherian, M M
2010-01-01
In this study, for the first time, the transverse vibrational model of a viscous-fluid-conveying single-walled carbon nanotube (SWCNT) embedded in biological soft tissue is developed. Nonlocal Euler-Bernoulli beam theory has been used to investigate fluid-induced vibration of the SWCNT while visco-elastic behaviour of the surrounding tissue is simulated by the Kelvin-Voigt model. The results indicate that the resonant frequencies and the critical flow velocity at which structural instability of nanotubes emerges are significantly dependent on the properties of the medium around the nanotube, the boundary conditions, the viscosity of the fluid and the nonlocal parameter. Detailed results are demonstrated for the dependence of damping and elastic properties of the medium on the resonant frequencies and the critical flow velocity. Three standard boundary conditions, namely clamped-clamped, clamped-pinned and pinned-pinned, are applied to study the effect of the supported end conditions. Furthermore, it is found that the visco-elastic foundation causes an obvious reduction in the critical velocity in comparison with the elastic foundation, in particular for a compliant medium, pinned-pinned boundary condition, high viscosity of the fluid and small values of the nonlocal coefficient.
First line shape analysis and spectroscopic parameters for the ν11 band of 12C2H4
Es-sebbar, Et-touhami
2016-08-11
An accurate knowledge of line intensities, collisional broadening coefficients and narrowing parameters is necessary for the interpretation of high-resolution infrared spectra of the Earth and other planetary atmospheres. One of the most promising spectral domains for (C2H4)-C-12 monitoring in such environments is located near the 336 gm window, through its v(11) C-H stretching mode. In this paper, we report an extensive study in which we precisely determine spectroscopic parameters of (C2H4)-C-12 v(11) band at 297 +/- 1 K, using a narrow Difference-Frequency-Generation (DFG) laser with 10(-4) cm(-1) resolution. Absorption measurements were performed in the 2975-2980 cm(-1) spectral window to investigate 32 lines corresponding to where, J\\'ka\\',kc\\'<- Jka,kc, 5 <= J <= 7; 0.5 <= K-a <= 6 and 1 <= K-c <= 14. Spectroscopic parameters are retrieved using either Voigt or appropriate Galatry profile to simulate the measured (C2H4)-C-12 line shape. Line intensities along with self-broadening coefficients are reported for all lines. Narrowing coefficients for each isolated line are also derived. To our knowledge, the current study reports the first extensive spectroscopic parameter measurements of the (C2H4)-C-12 v(11) band in the 2975-2980 cm(-1) range. (C) 2016 Elsevier Ltd. All rights reserved.
Some triterpenic compounds in extracts of Cecropia and Bauhinia species for different sampling years
Directory of Open Access Journals (Sweden)
Marcella Emilia Pietra Schmidt
Full Text Available ABSTRACT The aim of this paper is to provide an overview on the chemical composition of triterpenes in widespread used folk medicine species, through the development and validation of eleven compounds using HPLC-UV detection. The compounds were separated using isocratic elution, on a reverse phase column (Kinetex C18, 250 mm × 4.6 mm, 5 µm with mobile phase consisted of acetonitrile:tetrahydrofuran (90:10, v/v, flow-rate of 0.5 ml/min and detection in 210 nm. Diverse validation parameters were successfully evaluated. The samples of Bauhinia variegata L., B. variegata var. candida Voigt, Fabaceae, Cecropia palmata Willd. and C. obtusa Trécul, Urticaceae, collected in 2012, 2013 and 2014 from Amazon were treated with two different solvents (ethyl acetate and chloroform and analyzed by the proposed method. Stigmasterol, lupeol, β-sitosterol, β-amirin and α-amirin were found in all the studied plants. Highlighting the presence of oleanolic acid, maslinic acid in C. obtusa and C. palmata extracts, erythrodiol only in C. palmata, stigmasteol in B. variegata and α-amirin in B. variegata var. candida. Overall, ethyl acetate showed better performance as the extractor solvent than chloroform. Moreover, it could be used for the quality control of medicinal plants and to assess potential marker compounds.
Mechanochemical pattern formation in simple models of active viscoelastic fluids and solids
Alonso, Sergio; Radszuweit, Markus; Engel, Harald; Bär, Markus
2017-11-01
The cytoskeleton of the organism Physarum polycephalum is a prominent example of a complex active viscoelastic material wherein stresses induce flows along the organism as a result of the action of molecular motors and their regulation by calcium ions. Experiments in Physarum polycephalum have revealed a rich variety of mechanochemical patterns including standing, traveling and rotating waves that arise from instabilities of spatially homogeneous states without gradients in stresses and resulting flows. Herein, we investigate simple models where an active stress induced by molecular motors is coupled to a model describing the passive viscoelastic properties of the cellular material. Specifically, two models for viscoelastic fluids (Maxwell and Jeffrey model) and two models for viscoelastic solids (Kelvin-Voigt and Standard model) are investigated. Our focus is on the analysis of the conditions that cause destabilization of spatially homogeneous states and the related onset of mechano-chemical waves and patterns. We carry out linear stability analyses and numerical simulations in one spatial dimension for different models. In general, sufficiently strong activity leads to waves and patterns. The primary instability is stationary for all active fluids considered, whereas all active solids have an oscillatory primary instability. All instabilities found are of long-wavelength nature reflecting the conservation of the total calcium concentration in the models studied.
An ultrafast line-by-line algorithm for calculating spectral transmittance and radiance
International Nuclear Information System (INIS)
Tan, X.
2013-01-01
An ultrafast line-by-line algorithm for calculating spectral transmittance and radiance of gases is presented. The algorithm is based on fast convolution of the Voigt line profile using Fourier transform and a binning technique. The algorithm breaks a radiative transfer calculation into two steps: a one-time pre-computation step in which a set of pressure independent coefficients are computed using the spectral line information; a normal calculation step in which the Fourier transform coefficients of the optical depth are calculated using the line of sight information and the coefficients pre-computed in the first step, the optical depth is then calculated using an inverse Fourier transform and the spectral transmittance and radiance are calculated. The algorithm is significantly faster than line-by-line algorithms that do not employ special speedup techniques by a factor of 10 3 –10 6 . A case study of the 2.7 μm band of H 2 O vapor is presented. -- Highlights: •An ultrafast line-by-line model based on FFT and a binning technique is presented. •Computationally expensive calculations are factored out into a pre-computation step. •It is 10 3 –10 8 times faster than LBL algorithms that do not employ speedup techniques. •Good agreement with experimental data for the 2.7 μm band of H 2 O
Numerical modeling of bubble dynamics in viscoelastic media with relaxation
Warnez, M. T.; Johnsen, E.
2015-06-01
Cavitation occurs in a variety of non-Newtonian fluids and viscoelastic materials. The large-amplitude volumetric oscillations of cavitation bubbles give rise to high temperatures and pressures at collapse, as well as induce large and rapid deformation of the surroundings. In this work, we develop a comprehensive numerical framework for spherical bubble dynamics in isotropic media obeying a wide range of viscoelastic constitutive relationships. Our numerical approach solves the compressible Keller-Miksis equation with full thermal effects (inside and outside the bubble) when coupled to a highly generalized constitutive relationship (which allows Newtonian, Kelvin-Voigt, Zener, linear Maxwell, upper-convected Maxwell, Jeffreys, Oldroyd-B, Giesekus, and Phan-Thien-Tanner models). For the latter two models, partial differential equations (PDEs) must be solved in the surrounding medium; for the remaining models, we show that the PDEs can be reduced to ordinary differential equations. To solve the general constitutive PDEs, we present a Chebyshev spectral collocation method, which is robust even for violent collapse. Combining this numerical approach with theoretical analysis, we simulate bubble dynamics in various viscoelastic media to determine the impact of relaxation time, a constitutive parameter, on the associated physics. Relaxation time is found to increase bubble growth and permit rebounds driven purely by residual stresses in the surroundings. Different regimes of oscillations occur depending on the relaxation time.
Tutcuoglu, A.; Majidi, C.
2014-12-01
Using principles of damped harmonic oscillation with continuous media, we examine electrostatic energy harvesting with a "soft-matter" array of dielectric elastomer (DE) transducers. The array is composed of infinitely thin and deformable electrodes separated by layers of insulating elastomer. During vibration, it deforms longitudinally, resulting in a change in the capacitance and electrical enthalpy of the charged electrodes. Depending on the phase of electrostatic loading, the DE array can function as either an actuator that amplifies small vibrations or a generator that converts these external excitations into electrical power. Both cases are addressed with a comprehensive theory that accounts for the influence of viscoelasticity, dielectric breakdown, and electromechanical coupling induced by Maxwell stress. In the case of a linearized Kelvin-Voigt model of the dielectric, we obtain a closed-form estimate for the electrical power output and a scaling law for DE generator design. For the complete nonlinear model, we obtain the optimal electrostatic voltage input for maximum electrical power output.
International Nuclear Information System (INIS)
Ghayesh, Mergen H.; Amabili, Marco; Farokhi, Hamed
2013-01-01
In the present study, the coupled nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed is investigated employing a numerical technique. The equations of motion for both the transverse and longitudinal motions are obtained using Newton’s second law of motion and the constitutive relations. A two-parameter rheological model of the Kelvin–Voigt energy dissipation mechanism is employed in the modelling of the viscoelastic beam material, in which the material time derivative is used in the viscoelastic constitutive relation. The Galerkin method is then applied to the coupled nonlinear equations, which are in the form of partial differential equations, resulting in a set of nonlinear ordinary differential equations (ODEs) with time-dependent coefficients due to the axial acceleration. A change of variables is then introduced to this set of ODEs to transform them into a set of first-order ordinary differential equations. A variable step-size modified Rosenbrock method is used to conduct direct time integration upon this new set of first-order nonlinear ODEs. The mean axial speed and the amplitude of the speed variations, which are taken as bifurcation parameters, are varied, resulting in the bifurcation diagrams of Poincaré maps of the system. The dynamical characteristics of the system are examined more precisely via plotting time histories, phase-plane portraits, Poincaré sections, and fast Fourier transforms (FFTs)
International Nuclear Information System (INIS)
Saliba, J.
2012-01-01
In order to design reliable concrete structures, prediction of long term behaviour of concrete is important. In fact, creep deformation can cause mechanical deterioration and cracking, stress redistribution, loss in prestressed members and rarely ruin the structure. The aim of this research is to have a better understanding of the interaction between creep and crack growth in concrete. An experimental investigation on the fracture properties of concrete beams submitted to creep bending tests with high levels of sustained load is reported. The influence of creep on residual capacity and fracture energy of concrete is studied. In parallel, the acoustic emission technique (AE) was used to monitor crack development. The results give wealth information on damage evolution and show a decrease in the width of the fracture process zone (FPZ) characterizing a more brittle behaviour for beams subjected to creep. The AE shows that this may be due to the development of microcracking detected under creep. Based on those experimental results, a mesoscopic numerical study was proposed by coupling a damage model based on the micro-plan theory and a viscoelastic creep model defined by several Kelvin-voigt chains. The numerical results on concrete specimens in tension and in bending confirm the development of microcracks during creep at the mortar-aggregate interface. (author)
Energy Technology Data Exchange (ETDEWEB)
Martinez-Lozano, G. [Instituto Politecnico Nacional, ESFM, Av. IPN s/n, Edif. 9, UPALM, Mexico, D.F. 07738 (Mexico); Hesiquio-Garduno, M. [Instituto Politecnico Nacional, ESFM, Av. IPN s/n, Edif. 9, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: miguelhg@esfm.ipn.mx; Zeifert, B. [Instituto Politecnico Nacional, ESIQIE, Av. IPN s/n, Edif. 7, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: bzeifert@yahoo.com; Salmones, J. [Instituto Politecnico Nacional, ESIQIE, Av. IPN s/n, Edif. 7, UPALM, Mexico, D.F. 07738 (Mexico)]. E-mail: jose_salmones@yahoo.com.mx
2007-05-31
Co-hydrotalcite-like compounds (Co-HTlcs) were synthesized by coprecipitation technique from Mg(NO{sub 3}){sub 2}.6H{sub 2}O, Al(NO{sub 3}){sub 3}.9H{sub 2}O and Co(NO{sub 3}){sub 2}.6H{sub 2}O, with a constant molar ratio Mg/Al of 1.6 and a variable molar ratio Co/Mg from 0.01 to 0.1 (controlling the pH around 10). X-ray diffraction was used to evaluate structural (lattice parameters) and microstructural (crystallite size and microstrain) parameters of the samples. Lattice parameters were calculated from (0 0 3) (0 0 6) (1 1 0) and (1 1 3) reflections by the least squares method, changes on a and c lattice parameters are discussed and related to Co/Mg ratio. The microstructural parameters were analyzed using two approaches: (a) analytical methods with the Voigt method and the two stages approach and (b) graphical methods using a modified Williamson-Hall plot with Lorentzian, Gaussian and Lorentzian-Gaussian variants. It was found that increasing the Co content, the morphology of crystallites tends to be plate-like and it was observed that the crystallite size increases, while the microstrain values decrease. This behavior is related to an improvement of crystal perfection, due to addition of cobalt.
International Nuclear Information System (INIS)
Martinez-Lozano, G.; Hesiquio-Garduno, M.; Zeifert, B.; Salmones, J.
2007-01-01
Co-hydrotalcite-like compounds (Co-HTlcs) were synthesized by coprecipitation technique from Mg(NO 3 ) 2 .6H 2 O, Al(NO 3 ) 3 .9H 2 O and Co(NO 3 ) 2 .6H 2 O, with a constant molar ratio Mg/Al of 1.6 and a variable molar ratio Co/Mg from 0.01 to 0.1 (controlling the pH around 10). X-ray diffraction was used to evaluate structural (lattice parameters) and microstructural (crystallite size and microstrain) parameters of the samples. Lattice parameters were calculated from (0 0 3) (0 0 6) (1 1 0) and (1 1 3) reflections by the least squares method, changes on a and c lattice parameters are discussed and related to Co/Mg ratio. The microstructural parameters were analyzed using two approaches: (a) analytical methods with the Voigt method and the two stages approach and (b) graphical methods using a modified Williamson-Hall plot with Lorentzian, Gaussian and Lorentzian-Gaussian variants. It was found that increasing the Co content, the morphology of crystallites tends to be plate-like and it was observed that the crystallite size increases, while the microstrain values decrease. This behavior is related to an improvement of crystal perfection, due to addition of cobalt
Modelling viscoacoustic wave propagation with the lattice Boltzmann method.
Xia, Muming; Wang, Shucheng; Zhou, Hui; Shan, Xiaowen; Chen, Hanming; Li, Qingqing; Zhang, Qingchen
2017-08-31
In this paper, the lattice Boltzmann method (LBM) is employed to simulate wave propagation in viscous media. LBM is a kind of microscopic method for modelling waves through tracking the evolution states of a large number of discrete particles. By choosing different relaxation times in LBM experiments and using spectrum ratio method, we can reveal the relationship between the quality factor Q and the parameter τ in LBM. A two-dimensional (2D) homogeneous model and a two-layered model are tested in the numerical experiments, and the LBM results are compared against the reference solution of the viscoacoustic equations based on the Kelvin-Voigt model calculated by finite difference method (FDM). The wavefields and amplitude spectra obtained by LBM coincide with those by FDM, which demonstrates the capability of the LBM with one relaxation time. The new scheme is relatively simple and efficient to implement compared with the traditional lattice methods. In addition, through a mass of experiments, we find that the relaxation time of LBM has a quantitative relationship with Q. Such a novel scheme offers an alternative forward modelling kernel for seismic inversion and a new model to describe the underground media.
Es-sebbar, Et-touhami
2016-04-19
This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth\\'s atmosphere. © The Author(s) 2016.
Fast algorithm for spectral processing with application to on-line welding quality assurance
Mirapeix, J.; Cobo, A.; Jaúregui, C.; López-Higuera, J. M.
2006-10-01
A new technique is presented in this paper for the analysis of welding process emission spectra to accurately estimate in real-time the plasma electronic temperature. The estimation of the electronic temperature of the plasma, through the analysis of the emission lines from multiple atomic species, may be used to monitor possible perturbations during the welding process. Unlike traditional techniques, which usually involve peak fitting to Voigt functions using the Levenberg-Marquardt recursive method, sub-pixel algorithms are used to more accurately estimate the central wavelength of the peaks. Three different sub-pixel algorithms will be analysed and compared, and it will be shown that the LPO (linear phase operator) sub-pixel algorithm is a better solution within the proposed system. Experimental tests during TIG-welding using a fibre optic to capture the arc light, together with a low cost CCD-based spectrometer, show that some typical defects associated with perturbations in the electron temperature can be easily detected and identified with this technique. A typical processing time for multiple peak analysis is less than 20 ms running on a conventional PC.
Relativistic viscoelastic fluid mechanics
International Nuclear Information System (INIS)
Fukuma, Masafumi; Sakatani, Yuho
2011-01-01
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
International Nuclear Information System (INIS)
Niro, F.; Clarmann, T. von; Jucks, K.; Hartmann, J.-M.
2005-01-01
A theoretical model for the prediction of CO 2 absorption in both central and wing regions of infrared absorption bands was presented in the companion paper I. It correctly accounts for line-mixing effects and was validated by comparisons with laboratory spectra in the 600-1000 cm -1 region. This quality was confirmed using atmospheric transmissions measured by solar occultation experiments in the second paper. The present work completes these studies by now considering atmospheric emission in the 10-20 μm range. Comparisons are made between computed atmospheric radiances and measurements obtained using four different Fourier transform experiments collecting spectra for nadir, up-looking, as well as limb (from balloon and satellite) geometries. Our results confirm that using a Voigt model can lead to very large errors that affect the spectrum more than 300 cm -1 away from the center of the CO 2 ν 2 band. They also demonstrate the capability of our model to represent accurately the radiances in the entire region for a variety of atmospheric paths. This success opens interesting perspectives for the sounding of pressure and temperature profiles, particularly at low altitudes. Another benefit of the quality of the model should be an increased accuracy in the retrieval of atmospheric state parameters from broad features in the measured spectra (clouds, aerosols, heavy trace gases)
Radiative transport and collisional transfer of excitation energy in Cs vapors mixed with Ar or He
International Nuclear Information System (INIS)
Vadla, Cedomil; Horvatic, Vlasta; Niemax, Kay
2003-01-01
This paper is a review (with a few original additions) on the radiative transport and collisional transfer of energy in laser-excited cesium vapors in the presence of argon or helium. Narrow-band excitation of lines with Lorentz, Doppler and Voigt profiles is studied in order to calculate effective rates for pumping of spectral lines with profiles comprising inhomogeneous broadening components. The radiative transport of excitation energy is considered, and a new, simple and robust, but accurate theoretical method for quantitative treatment of radiation trapping in relatively optically thin media is presented. Furthermore, comprehensive lists of experimental values for the excitation energy transfer cross-sections related to thermal collisions in Cs-Ar and Cs-He mixtures are given. Within the collected cross-section data sets, specific regularities with respect to the energy defect, as well as the temperature, are discerned. A particular emphasis is put on the radiative and collisional processes important for the optimization of resonance-fluorescence imaging atomic filters based on Cs-noble gas systems
Baraskar, Priyanka; Chouhan, Romita; Agrawal, Arpana; Choudhary, R. J.; Sen, Pranay K.; Sen, Pratima
2018-03-01
We report the magnetic field effect on the linear and nonlinear optical properties of pulse laser ablated Ti-incorporated Cr2O3 nanostructured thin film. Optical properties have been experimentally analyzed under Voigt geometry by performing ultraviolet-visible spectroscopy and closed aperture Z-scan technique using a continuous wave He-Ne laser source. Nonlinear optical response reveals a single peak-valley feature in the far field diffraction pattern in absence of magnetic field (B = 0) confirming self-defocussing effect. This feature switches to a valley-peak configuration for B = 5000G, suggesting self-focusing effect. For B ≤ 750G, oscillations were observed revealing the occurrence of higher order nonlinearity. Origin of nonlinearity is attributed to the near resonant d-d transitions observed from the broad peak occurring around 2 eV. These transitions are of magnetic origin and get modified under the application of external magnetic field. Our results suggest that magnetic field can be used as an effective tool to monitor the sign of optical nonlinearity and hence the thermal expansion in Ti-incorporated Cr2O3 nanostructured thin film.
Relativistic viscoelastic fluid mechanics.
Fukuma, Masafumi; Sakatani, Yuho
2011-08-01
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski space-time become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
Effect of the anisotropy of the electron g-factor in spin polarization
Energy Technology Data Exchange (ETDEWEB)
Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); Department of Physics, University of Chittagong, Chittagong, Chittagong 4331 (Bangladesh); Gray, E. MacA. [Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Brisbane, QLD 4111 (Australia); School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)
2010-02-15
Spin polarization in the presence of an external magnetic field and electric bias in quantum confined semiconductor structures has been studied by time- and polarization-resolved spectrometry. From measurements with angular variations of the magnetic field from the Voigt configuration (VC) it was found that both the frequency ({Omega}) and decay rate ({beta}) of the oscillatory component of the polarization increase with variation of the angle from the VC. Their dependences are discussed based on the electron spin dephasing related to the spread of the electron g-factor (g{sub e}) (i.e. unequal values of the longitudinal (g{sub e||}) and transverse (g{sub e}-perpendicular) components of g{sub e}) and the exchange interaction between the electron and hole spins. It is demonstrated that the increase in {Omega} upon deviation of the magnetic field from the VC relates to the anisotropy of g{sub e} (g{sub e||} and g{sub e}-perpendicular) resulting from the quantum confinement effect. However, the angular dependence on {beta} is related to the residual exchange interaction between the electron spin and rapidly relaxing hole spin.
Ultra-fast and calibration-free temperature sensing in the intrapulse mode
Chrystie, Robin S. M.; Nasir, Ehson F.; Farooq, Aamir
2014-01-01
A simultaneously time-resolved and calibration-free sensor has been demonstrated to measure temperature at the nanosecond timescale at repetition rates of 1.0 MHz. The sensor benefits from relying on a single laser, is intuitive and straightforward to implement, and can sweep across spectral ranges in excess of 1 cm-1. The sensor can fully resolve rovibrational features of the CO molecule, native to combustion environments, in the mid-infrared range near X = 4.85 μm at typical combustion temperatures (800-2500 K) and pressures (1-3 atm). All of this is possible through the exploitation of chirp in a quantum cascade laser, operating at a duty cycle of 50%, and by using high bandwidth (500 MHz) photodetection. Here, we showcase uncluttered, spectrally-pure Voigt profile fitting with accompanying peak SNRs of 150, resulting in a typical temperature precision of 0.9% (1u) at an effective time-resolution of 1.0 MHz. Our sensor is applicable to other species, and canbe integrated into commercial technologies.
Energy Technology Data Exchange (ETDEWEB)
Klatt, Dieter [Department of Radiology, Charite-Universitaetsmedizin Berlin, Campus Charite Mitte, Chariteplatz 1, 10117 Berlin (Germany); Hamhaber, Uwe [Institute of Medical Informatics, Charite-Universitaetsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin (Germany); Asbach, Patrick [Department of Radiology, Charite-Universitaetsmedizin Berlin, Campus Charite Mitte, Chariteplatz 1, 10117 Berlin (Germany); Braun, Juergen [Institute of Medical Informatics, Charite-Universitaetsmedizin Berlin, Campus Benjamin Franklin, Hindenburgdamm 30, 12200 Berlin (Germany); Sack, Ingolf [Department of Radiology, Charite-Universitaetsmedizin Berlin, Campus Charite Mitte, Chariteplatz 1, 10117 Berlin (Germany)
2007-12-21
MR elastography (MRE) enables the noninvasive determination of the viscoelastic behavior of human internal organs based on their response to oscillatory shear stress. An experiment was developed that combines multifrequency shear wave actuation with broad-band motion sensitization to extend the dynamic range of a single MRE examination. With this strategy, multiple wave images corresponding to different driving frequencies are simultaneously received and can be analyzed by evaluating the dispersion of the complex modulus over frequency. The technique was applied on the brain and liver of five healthy volunteers. Its repeatability was tested by four follow-up studies in each volunteer. Five standard rheological models (Maxwell, Voigt, Zener, Jeffreys and fractional Zener model) were assessed for their ability to reproduce the observed dispersion curves. The three-parameter Zener model was found to yield the most consistent results with two shear moduli {mu}{sub 1} = 0.84 {+-} 0.22 (1.36 {+-} 0.31) kPa, {mu}{sub 2} = 2.03 {+-} 0.19 (1.86 {+-} 0.34) kPa and one shear viscosity of {eta} = 6.7 {+-} 1.3 (5.5 {+-} 1.6) Pa s (interindividual mean {+-} SD) in brain (liver) experiments. Significant differences between the rheological parameters of brain and liver were found for {mu}{sub 1} and {eta} (P < 0.05), indicating that human brain is softer and possesses a higher viscosity than liver.
International Nuclear Information System (INIS)
Klatt, Dieter; Hamhaber, Uwe; Asbach, Patrick; Braun, Juergen; Sack, Ingolf
2007-01-01
MR elastography (MRE) enables the noninvasive determination of the viscoelastic behavior of human internal organs based on their response to oscillatory shear stress. An experiment was developed that combines multifrequency shear wave actuation with broad-band motion sensitization to extend the dynamic range of a single MRE examination. With this strategy, multiple wave images corresponding to different driving frequencies are simultaneously received and can be analyzed by evaluating the dispersion of the complex modulus over frequency. The technique was applied on the brain and liver of five healthy volunteers. Its repeatability was tested by four follow-up studies in each volunteer. Five standard rheological models (Maxwell, Voigt, Zener, Jeffreys and fractional Zener model) were assessed for their ability to reproduce the observed dispersion curves. The three-parameter Zener model was found to yield the most consistent results with two shear moduli μ 1 = 0.84 ± 0.22 (1.36 ± 0.31) kPa, μ 2 = 2.03 ± 0.19 (1.86 ± 0.34) kPa and one shear viscosity of η = 6.7 ± 1.3 (5.5 ± 1.6) Pa s (interindividual mean ± SD) in brain (liver) experiments. Significant differences between the rheological parameters of brain and liver were found for μ 1 and η (P < 0.05), indicating that human brain is softer and possesses a higher viscosity than liver
Quantitative analysis of lattice disorder and crystallite size in organic semiconductor thin films
Rivnay, Jonathan
2011-07-07
The crystallite size and cumulative lattice disorder of three prototypical, high-performing organic semiconducting materials are investigated using a Fourier-transform peak shape analysis routine based on the method of Warren and Averbach (WA). A thorough incorporation of error propagation throughout the multistep analysis and a weighted fitting of Fourier-transformed data to the WA model allows for more accurate results than typically obtained and for determination of confidence bounds. We compare results obtained when assuming two types of column-length distributions, and discuss the benefits of each model in terms of simplicity and accuracy. For strongly disordered materials, the determination of a crystallite size is greatly hindered because disorder dominates the coherence length, not finite size. A simple analysis based on trends of peak widths and Lorentzian components of pseudo-Voigt line shapes as a function of diffraction order is also discussed as an approach to more easily and qualitatively assess the amount and type of disorder present in a sample. While applied directly to organic systems, this methodology is general for the accurate deconvolution of crystalline size and lattice disorder for any material investigated with diffraction techniques. © 2011 American Physical Society.
Remenieras, Jean-Pierre; Dejobert, Maelle; Bastard, Cécile; Miette, Véronique; Perarnau, Jean-Marc; Patat, Frédéric
Nonalcoholic fatty liver disease (NAFLD) is characterized by accumulation of fat within the Liver. The main objective of this work is (1) to evaluate the feasibility of measuring in vivo in the liver the shear wave phase velocity dispersion cs(ω) between 20 Hz and 90 Hz using vibration-controlled transient elastography (VCTE); (2) to estimate through the rheological Kelvin-Voigt model the shear elastic μ and shear viscosity η modulus; (3) to correlate the evolution of these viscoelastic parameters on two patients at Tours Hospital with the hepatic fat percentage measured with T1-weighted gradient-echo in-and out-phase MRI sequence. For the first volunteer who has 2% of fat in the liver, we obtained μ = 1233 ± 133 Pa and η = 0.5 ± 0.4 Pa.s. For the patient with 22% of fat, we measure μ = 964 ± 91 Pa and η = 1.77 ± 0.3 Pa.s. In conclusion, this novel method showed to be sensitive in characterizing the visco-elastic properties of fatty liver.
Muscle co-contraction modulates damping and joint stability in a three-link bio mechanical limb
Directory of Open Access Journals (Sweden)
Stewart eHeitmann
2012-01-01
Full Text Available Computational models of neuromotor control require forward models of limb movement that can replicate the natural relationships between muscle activation and joint dynamics without the burdens of excessive anatomical detail. We present a model of a three-link biomechanical limb that emphasizes the dynamics of limb movement within a simplified two-dimensional framework. Muscle co-contraction effects were incorporated into the model by flanking each joint with a pair of antagonist muscles that may be activated independently. Muscle co-contraction is known to alter the damping and stiffness of limb joints without altering net joint torque. Idealized muscle actuators were implemented using the Voigt muscle model which incorporates the parallel elasticity of muscle and tendon but omits series elasticity. The natural force-length-velocity relationships of contractile muscle tissue were incorporated into the actuators using ideal mathematical forms. Numerical stability analysis confirmed that co-contraction of these simplified actuators increased damping in the biomechanical limb consistent with observations of human motor control. Dynamic changes in joint stiffness were excluded by the omission of series elasticity. The analysis also revealed the unexpected finding that distinct stable (bistable equilibrium positions can co-exist under identical levels of muscle co-contraction. We map the conditions under which bistability arises and prove analytically that monostability (equifinality is guaranteed when the antagonist muscles are identical. Lastly we verify these analytic findings in the full biomechanical limb model.
Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder
International Nuclear Information System (INIS)
Mehran, E; Farjami Shayesteh, S; Sheykhan, M
2016-01-01
The structural and magnetic properties of the synthesized pure and functionalized CoFe 2 O 4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT–IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. (paper)
Es-sebbar, Et-touhami; Deli, Meriem; Farooq, Aamir
2016-01-01
This study deals with precise measurements of absolute line intensities, N2-, O2- and Ar- collisional broadening coefficients of N2O in the P-branch of the ν3 vibrational band near 4.5 μm. Collisional broadening coefficients of N2O-air are derived from the N2- and O2- broadening contributions by considering an ideal atmospheric composition. Studies are performed at room temperature for 10 rotational transitions over 2190-2202 cm-1 spectral range using a distributed-feedback quantum cascade laser. To retrieve spectroscopic parameters for each individual transition, measured absorption line shape is simulated within Voigt and Galatry profiles. The obtained results compare well with previous experimental data available in the literature: the discrepancies being less than 4% for most of the probed transitions. The spectroscopic data reported here are very useful for the design of sensors used to monitor the abundance of N2O in earth's atmosphere. © The Author(s) 2016.
Huang, Junjie; Wang, Zhou; Gan, Jin; Yang, Ying; Huang, Feng; Wu, Gang; Meng, Qingshuai
2018-05-01
In order to investigate the recrystallization behavior of peened surface deformation layer of precipitation hardening stainless steel, a classic x-ray diffraction line profile analysis, Voigt method, was carried out on peened 17-4PH with different isothermal annealing temperatures. The activation energy of domain boundary migration ( Q a) and the activation energy of microstrain relaxation ( Q b) were calculated by regression analysis in different annealing temperature conditions. The results show that the value of Q a decreases with annealing temperature increasing, which is due to the influence of precipitation (ɛ-Cu) size on the movements of grain and subgrain boundaries. The maximum growth rate of ɛ-Cu particles occurs during 400 to 500 °C interval. Compared with growth behavior of domain size, microstrain relaxation behavior is less sensitive to precipitation particle size. The effects of annealing temperature and time on dislocation density are both significant when annealing temperature is lower than 500 °C. However, the effect of annealing temperature on dislocation density becomes insignificant when annealing temperature is higher than 500 °C. 300 °C annealing temperature only leads to the microstrain relaxation but nearly cannot lead to the domain size growth even if prolonging annealing time. Microstructure enhancement effect still exists in plastic deformation layer when 300 °C annealing temperature lasts for 60 min but nearly disappears when 600 °C annealing temperature lasts for 20 min.
International Nuclear Information System (INIS)
Wang, Zhuqing; Stoica, Alexandru D.; Ma, Dong; Beese, Allison M.
2016-01-01
In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
International Nuclear Information System (INIS)
Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R.A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.
2012-01-01
Room-temperature N 2 -broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH 3 Cl-N 2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.
Tail modeling in a stretched magnetosphere 1. Methods and transformations
International Nuclear Information System (INIS)
Stern, D.P.
1987-01-01
A new method is developed for representing the magnetospheric field B as a distorted dipole field. Because delxB = 0 must be maintained,such a distortion may be viewed as a transformation of the vector potential A. The simplest form is a one-dimensional ''stretch transformation'' along the x axis, a generalization of a method introduced by Voigt. The transformation is concisely represented by the ''stretch function'' f(x), which is also a convenient tool for representing features of the substorm cycle. Onedimensional stretch transformations are extended to spherical, cylindrical, and parabolic coordinates and then to arbitrary coordinates. It is next shown that distortion transformations can be viewed as mappings of field lines from one pattern to another: Euler potentials are used in the derivation, but the final result only requires knowledge of the field and not of the potentials. General transformations in Cartesian and arbitrary coordinates are then derived,and applications to field modeling, field line motion, MHD modeling, and incompressible fluid dynamics are considered. copyrightAmerican Geophysical Union 1987
An impedance spectroscopy investigation of nanocrystalline CsPbBr{sub 3} films
Energy Technology Data Exchange (ETDEWEB)
Vitale, G. [Department of Electronic Engineering and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Conte, G. [Department of Electronic Engineering and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy)]. E-mail: gconte@ele.uniroma3.it; Aloe, P. [Department of Physics and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy); Somma, F. [Department of Physics and INFM, University of Rome ' Roma Tre' , Via della Vasca Navale 84, 00146 Rome (Italy)
2005-12-15
Thin films of CsPbBr{sub 3} were prepared by co-evaporation of CsBr and PbBr{sub 2} powders. Deposited materials are constituted by nanometer-sized crystals as evidenced by atomic force microscopy and X ray diffraction. Impedance spectroscopy measurements, aimed to study the dielectric relaxation processes and transport mechanisms at grain boundary and grain interior, reveal a complex response of the material both on the frequency and on the temperature variations. DC current voltage curves are ohmic for applied electric field strength up to 2 x 10{sup 6} V/cm. The DC conductivity Arrhenius plot gives a value of the activation energy equal to 0.85 eV, smaller then that expected for an intrinsic semiconductor. On the other hand, impedance measurements on a wide frequency range and at different temperatures can be reduced to a single master curve addressing hopping transport mechanism and dielectric relaxation processes being active. Finally, a simple model based on multiple Voigt's elements has been used to fit the impedance spectroscopy data and to evaluate relevant material parameters.
Wang, Yun-Jiang; Wang, Chong-Yu
2009-10-01
A model system consisting of Ni[001](100)/Ni3Al[001](100) multi-layers are studied using the density functional theory in order to explore the elastic properties of single crystal Ni-based superalloys. Simulation results are consistent with the experimental observation that rafted Ni-base superalloys virtually possess a cubic symmetry. The convergence of the elastic properties with respect to the thickness of the multilayers are tested by a series of multilayers from 2γ'+2γ to 10γ'+10γ atomic layers. The elastic properties are found to vary little with the increase of the multilayer's thickness. A Ni/Ni3Al multilayer with 10γ'+10γ atomic layers (3.54 nm) can be used to simulate the mechanical properties of Ni-base model superalloys. Our calculated elastic constants, bulk modulus, orientation-dependent shear modulus and Young's modulus, as well as the Zener anisotropy factor are all compatible with the measured results of Ni-base model superalloys R1 and the advanced commercial superalloys TMS-26, CMSX-4 at a low temperature. The mechanical properties as a function of the γ' phase volume fraction are calculated by varying the proportion of the γ and γ' phase in the multilayers. Besides, the mechanical properties of two-phase Ni/Ni3Al multilayer can be well predicted by the Voigt-Reuss-Hill rule of mixtures.
Huang, Junjie; Wang, Zhou; Gan, Jin; Yang, Ying; Huang, Feng; Wu, Gang; Meng, Qingshuai
2018-04-01
In order to investigate the recrystallization behavior of peened surface deformation layer of precipitation hardening stainless steel, a classic x-ray diffraction line profile analysis, Voigt method, was carried out on peened 17-4PH with different isothermal annealing temperatures. The activation energy of domain boundary migration (Q a) and the activation energy of microstrain relaxation (Q b) were calculated by regression analysis in different annealing temperature conditions. The results show that the value of Q a decreases with annealing temperature increasing, which is due to the influence of precipitation (ɛ-Cu) size on the movements of grain and subgrain boundaries. The maximum growth rate of ɛ-Cu particles occurs during 400 to 500 °C interval. Compared with growth behavior of domain size, microstrain relaxation behavior is less sensitive to precipitation particle size. The effects of annealing temperature and time on dislocation density are both significant when annealing temperature is lower than 500 °C. However, the effect of annealing temperature on dislocation density becomes insignificant when annealing temperature is higher than 500 °C. 300 °C annealing temperature only leads to the microstrain relaxation but nearly cannot lead to the domain size growth even if prolonging annealing time. Microstructure enhancement effect still exists in plastic deformation layer when 300 °C annealing temperature lasts for 60 min but nearly disappears when 600 °C annealing temperature lasts for 20 min.
The analysis of thermoplastic characteristics of special polymer sulfur composite
Książek, Mariusz
2017-01-01
Specific chemical environments step out in the industry objects. Portland cement composites (concrete and mortar) were impregnated by using the special polymerized sulfur and technical soot as a filler (polymer sulfur composite). Sulfur and technical soot was applied as the industrial waste. Portland cement composites were made of the same aggregate, cement and water. The process of special polymer sulfur composite applied as the industrial waste is a thermal treatment process in the temperature of about 150-155°C. The result of such treatment is special polymer sulfur composite in a liquid state. This paper presents the plastic constants and coefficients of thermal expansion of special polymer sulfur composites, with isotropic porous matrix, reinforced by disoriented ellipsoidal inclusions with orthotropic symmetry of the thermoplastic properties. The investigations are based on the stochastic differential equations of solid mechanics. A model and algorithm for calculating the effective characteristics of special polymer sulfur composites are suggested. The effective thermoplastic characteristics of special polymer sulfur composites, with disoriented ellipsoidal inclusions, are calculated in two stages: First, the properties of materials with oriented inclusions are determined, and then effective constants of a composite with disoriented inclusions are determined on the basis of the Voigt or Rice scheme. A brief summary of new products related to special polymer sulfur composites is given as follows: Impregnation, repair, overlays and precast polymer concrete will be presented. Special polymer sulfur as polymer coating impregnation, which has received little attention in recent years, currently has some very interesting applications.
Resonance fluorescence spectrum of a p-doped quantum dot coupled to a metallic nanoparticle
Carreño, F.; Antón, M. A.; Arrieta-Yáñez, Francisco
2013-11-01
The resonance fluorescence spectrum (RFS) of a hybrid system consisting of a p-doped semiconductor quantum dot (QD) coupled to a metallic nanoparticle (MNP) is analyzed. The quantum dot is described as a four-level atomlike system using the density matrix formalism. The lower levels are Zeeman-split hole spin states and the upper levels correspond to positively charged excitons containing a spin-up, spin-down hole pair and a spin electron. A linearly polarized laser field drives two of the optical transitions of the QD and produces localized surface plasmons in the nanoparticle, which act back upon the QD. The frequencies of these localized plasmons are very different along the two principal axes of the nanoparticle, thus producing an anisotropic modification of the spontaneous emission rates of the allowed optical transitions, which is accompanied by very minor local field corrections. This manifests into dramatic modifications in the RFS of the hybrid system in contrast to the one obtained for the isolated QD. The RFS is analyzed as a function of the nanoparticle's aspect ratio, the external magnetic field applied in the Voigt geometry, and the Rabi frequency of the driving field. It is shown that the spin of the QD is imprinted onto certain sidebands of the RFS, and that the signal at these sidebands can be optimized by engineering the shape of the MNP.
Directory of Open Access Journals (Sweden)
Bartlewska-Urban Monika
2015-02-01
Full Text Available The following study presents numerical calculations for establishing an impact of temperature changes on the process of distortion of bi–phase medium. The Biot consolidation equations with Kelvin–Voigt rheological skeleton were used for that purpose. The process was exemplified by thermal consolidation of post floatation dump “–elazny Most”. We analyzed the behavior of the landfill under the action of its own weight, forces of floating filtration and temperature gradient. Values of certain effective parameters of model were obtained during laboratory tests on material obtained from the landfill. The remaining data for mediums with similar characteristics were taken from literature. The results obtained from the stress state in the landfill allow the magnitude of plasticity potential to be specified based on known strength criteria. Change in the value sign of the plasticity potential clearly testifies to the emergence of an area of plasticity of material from landfill, however, this does not indicate the loss of stability of this hydrotechnical structure.
Generalized dielectric permittivity tensor
International Nuclear Information System (INIS)
Borzdov, G.N.; Barkovskii, L.M.; Fedorov, F.I.
1986-01-01
The authors deal with the question of what is to be done with the formalism of the electrodynamics of dispersive media based on the introduction of dielectric-permittivity tensors for purely harmonic fields when Voigt waves and waves of more general form exist. An attempt is made to broaden and generalize the formalism to take into account dispersion of waves of the given type. In dispersive media, the polarization, magnetization, and conduction current-density vectors of point and time are determined by the values of the electromagnetic field vectors in the vicinity of this point (spatial dispersion) in the preceding instants of time (time dispersion). The dielectric-permittivity tensor and other tensors of electrodynamic parameters of the medium are introduced in terms of a set of evolution operators and not the set of harmonic function. It is noted that a magnetic-permeability tensor and an elastic-modulus tensor may be introduced for an acoustic field in dispersive anisotropic media with coupling equations of general form
Mechanical properties of layered oxysulfide CaZnOS from first principle calculations
Energy Technology Data Exchange (ETDEWEB)
Zhang, Zhi-Jun [Department of Physics, Dongguk University, Pildong-ro, Choong-gu, Seoul, 100-715 (Korea, Republic of); Feng, Ang [Key Laboratory of Transparent Opto-Functional Inorganic Materials of Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, 200050 (China); Zhang, Shao-Lin; Zhang, Wei-Bin [Department of Physics, Dongguk University, Pildong-ro, Choong-gu, Seoul, 100-715 (Korea, Republic of); Yang, Woochul, E-mail: wyang@dongguk.edu [Department of Physics, Dongguk University, Pildong-ro, Choong-gu, Seoul, 100-715 (Korea, Republic of)
2016-06-15
Elastic and tensile properties of mixed-anion oxysulfide CaZnOS have been theoretically investigated by first principle method of density functional theory (DFT). Elastic constants were obtained by stress–strain relationships, and bulk structure parameters including bulk modulus, shear modulus, as well as Poisson's ratio were then calculated using Voigt-Reuses-Hill (VRH) approximation. The results of shear anisotropic factors, compressibility anisotropic factor and directional Young's modulus showed that CaZnOS is almost elastically isotropic in {001} planes and maintains elastic anisotropy in {100} or {010} planes. Chemical bond anisotropy shown by Mulliken atomic charges and bond overlap populations is responsible for the elastic anisotropy behavior aforementioned. Moreover, theoretical uniaxial and biaxial tensile results showed the crystal collapsed at strain more than 12%, except in the biaxial extension where CaZnOS collapsed at strain of 7%. - Highlights: • Elastic and theoretical tensile properties of CaZnOS have been investigated by first principle method. • CaZnOS is elastically isotropic in {001} planes and maintains elastic anisotropy in {100} or {010} planes. • Mulliken atomic charges and bond overlap populations are responsible for the elastic anisotropy behavior.
Guinet, M.; Rohart, F.; Buldyreva, J.; Gupta, V.; Eliet, S.; Motiyenko, R. A.; Margulès, L.; Cuisset, A.; Hindle, F.; Mouret, G.
2012-07-01
Room-temperature N2-broadening coefficients of methyl chloride rotational lines are measured over a large interval of quantum numbers (6≤J≤50, 0≤K≤18) by a submillimeter frequency-multiplication chain (J≤31) and a terahertz photomixing continuous-wave spectrometer (J≥31). In order to check the accuracy of both techniques, the measurements of identical lines are compared for J=31. The pressure broadening coefficients are deduced from line fits using mainly a Voigt profile model. The excellent signal-to-noise ratio of the frequency-multiplication scheme highlights some speed dependence effect on the line shape. Theoretical values of these coefficients are calculated by a semi-classical approach with exact trajectories. An intermolecular potential including atom-atom interactions is used for the first time. It is shown that, contrary to the previous theoretical predictions, the contributions of short-range forces are important for all values of the rotational quantum numbers. Additional testing of modifications required in the semi-classical formalism for a correct application of the cumulant expansion is also performed. It is stated that the use of the cumulant average on the rotational states of the perturbing molecule leads, for high J and small K values, to slightly higher line-broadening coefficients, as expected for the relatively strong interacting CH3Cl-N2 system. The excellent agreement between the theoretical and the experimental results ensures the reliability of these data.
Freeman, John W.
2000-10-01
Rice University has developed a dynamic model of the Earth's radiation belts based on real-time data driven boundary conditions and full adiabaticity. The Radiation Belt Test Model (RBTM) successfully replicates the major features of storm-time behavior of energetic electrons: sudden commencement induced main phase dropout and recovery phase enhancement. It is the only known model to accomplish the latter. The RBTM shows the extent to which new energetic electrons introduced to the magnetosphere near the geostationary orbit drift inward due to relaxation of the magnetic field. It also shows the effects of substorm related rapid motion of magnetotail field lines for which the 3rd adiabatic invariant is violated. The radial extent of this violation is seen to be sharply delineated to a region outside of 5Re, although this distance is determined by the Hilmer-Voigt magnetic field model used by the RBTM. The RBTM appears to provide an excellent platform on which to build parameterized refinements to compensate for unknown acceleration processes inside 5Re where adiabaticity is seen to hold. Moreover, built within the framework of the MSFM, it offers the prospect of an operational forecast model for MeV electrons.
Structural and magnetic properties of turmeric functionalized CoFe2O4 nanocomposite powder
Mehran, E.; Farjami Shayesteh, S.; Sheykhan, M.
2016-10-01
The structural and magnetic properties of the synthesized pure and functionalized CoFe2O4 magnetic nanoparticles (NPs) are studied by analyzing the results from the x-ray diffraction (XRD), transmission electron microscopy (TEM), FT-IR spectroscopy, thermogravimetry (TG), and vibrating sample magnetometer (VSM). To extract the structure and lattice parameters from the XRD analysis results, we first apply the pseudo-Voigt model function to the experimental data obtained from XRD analysis and then the Rietveld algorithm is used in order to optimize the model function to estimate the true intensity values. Our simulated intensities are in good agreement with the experimental peaks, therefore, all structural parameters such as crystallite size and lattice constant are achieved through this simulation. Magnetic analysis reveals that the synthesized functionalized NPs have a saturation magnetization almost equal to that of pure nanoparticles (PNPs). It is also found that the presence of the turmeric causes a small reduction in coercivity of the functionalized NPs in comparison with PNP. Our TGA and FTIR results show that the turmeric is bonded very well to the surface of the NPs. So it can be inferred that a nancomposite (NC) powder of turmeric and nanoparticles is produced. As an application, the anti-arsenic characteristic of turmeric makes the synthesized functionalized NPs or NC powder a good candidate for arsenic removal from polluted industrial waste water. Project supported by the University of Guilan and the Iran Nanotechnology Initiative Council.
Determining the Viscosity Coefficient for Viscoelastic Wave Propagation in Rock Bars
Niu, Leilei; Zhu, Wancheng; Li, Shaohua; Guan, Kai
2018-05-01
Rocks with microdefects exhibit viscoelastic behavior during stress wave propagation. The viscosity coefficient of the wave can be used to characterize the attenuation as the wave propagates in rock. In this study, a long artificial bar with a readily adjustable viscosity coefficient was fabricated to investigate stress wave attenuation. The viscoelastic behavior of the artificial bar under dynamic loading was investigated, and the initial viscoelastic coefficient was obtained based on the amplitude attenuation of the incident harmonic wave. A one-dimensional wave propagation program was compiled to reproduce the time history of the stress wave measured during the experiments, and the program was well fitted to the Kelvin-Voigt model. The attenuation and dispersion of the stress wave in long artificial viscoelastic bars were quantified to accurately determine the viscoelastic coefficient. Finally, the method used to determine the viscoelastic coefficient of a long artificial bar based on the experiments and numerical simulations was extended to determine the viscoelastic coefficient of a short rock bar. This study provides a new method of determining the viscosity coefficient of rock.
Jamalpoor, A.; Ahmadi-Savadkoohi, A.; Hosseini-Hashemi, Sh
2016-10-01
This paper deals with the theoretical analysis of free vibration and biaxial buckling of magneto-electro-elastic (MEE) microplate resting on Kelvin-Voigt visco-Pasternak foundation and subjected to initial external electric and magnetic potentials, using modified strain gradient theory (MSGT). Kirchhoff plate model and Hamilton’s principle are employed to extract the governing equations of motion. Governing equations were analytically solved to obtain clear closed-form expression for complex natural frequencies and buckling loads using Navier’s approach. Numerical results are presented to reveal variations of natural frequency and buckling load ratio of MEE microplate against different amounts of the length scale parameter, initial external electric and magnetic potentials, aspect ratio, damping and transverse and shear stiffness parameters of the visco-Pasternak foundation, length to thickness ratio, microplate thickness and higher modes. Numerical results of this study illustrate that by increasing thickness-to-material length scale parameter ratio, both natural frequency and buckling load ratio predicted by MSGT and modified couple stress theory are reduced because the non-dimensional length scale parameter tends to decrease the stiffness of structures and make them more flexible. In addition, results show that initial external electric and initial external magnetic potentials have no considerable influence on the buckling load ratio and frequency of MEE microplate as the microplate thickness increases.
VizieR Online Data Catalog: CoRoT red giants abundances (Morel+, 2014)
Morel, T.; Miglio, A.; Lagarde, N.; Montalban, J.; Rainer, M.; Poretti, E.; Eggenberger, P.; Hekker, S.; Kallinger, T.; Mosser, B.; Valentini, M.; Carrier, F.; Hareter, M.; Mantegazza, L.
2014-02-01
The equivalent widths were measured manually assuming Gaussian profiles or Voigt profiles for the few lines with extended damping wings. Lines with an unsatisfactory fit or significantly affected by telluric features were discarded. Only values eventually retained for the analysis are provided. For the chemical abundances, the usual notation is used: [X/Y]=[log({epsilon}(X))-log({epsilon}(Y))]star - [log({epsilon}(X))-log({epsilon}(Y))]⊙ with log{epsilon}(X)=12+log[N(X)/N(H)] (N is the number density of the species). For lithium, the following notation is used: [Li/H]=log(N(Li))star-log(N(Li))⊙. The adopted solar abundances are taken from Grevesse & Sauval (1998SSRv...85..161G), except for Li for which we adopt our derived values: log({epsilon}(Li))⊙=1.09 and 1.13 in LTE and NLTE, respectively (see text). All the abundances are computed under the assumption of LTE, except Li for which values corrected for departures from LTE using the data of Lind et al. (2009A&A...503..541L) are also provided. All the quoted error bars are 1-sigma uncertainties. (6 data files).
Mapping of the solar wind electric field to the Earth's polar caps
International Nuclear Information System (INIS)
Toffoletto, F.R.; Hill, T.W.
1989-01-01
In this paper we describe a quantitative model of a magnetically interconnected (open) magnetosphere, developed as a perturbation to Voigt's closed magnetosphere model with a given magnetopause shape. The ''interconnection'' (perturbation) field is obtained as a solution to a Neumann boundary value problem, with the magnetopause normal component distribution as a boundary condition. The normal component at the magnetopause is required to be time independent and is specified in accordance with one of two hypotheses: the subsolar point merging hypothesis and Crooker's antiparallel merging hypothesis. The resulting open magnetospheric configuration is used to map the magnetopause electric field down to the polar cap ionosphere. We present ionospheric convection patterns derived from three representative interplanetary magnetic field (IMF) orientations for each of the two dayside merging geometries. Both merging geometries reproduce the observed convergence of convection streamlines near noon in a convection ''throat,'' and the east-west deflection of these streamlines in response to the east-west IMF component. The major difference between the two dayside merging geometries occurs for nonsouthward IMF, and consists of a Sun-aligned convection gap that bifurcates the polar cap in the case of the antiparallel merging geometry but not in the subsolar point merging geometry. This convection gap may plausibly be associated with the ''theta aurora'' structure observed when the IMF has a northward component. copyright American Geophysical Union 1989
Ultra-fast and calibration-free temperature sensing in the intrapulse mode
Chrystie, Robin S. M.
2014-11-20
A simultaneously time-resolved and calibration-free sensor has been demonstrated to measure temperature at the nanosecond timescale at repetition rates of 1.0 MHz. The sensor benefits from relying on a single laser, is intuitive and straightforward to implement, and can sweep across spectral ranges in excess of 1 cm-1. The sensor can fully resolve rovibrational features of the CO molecule, native to combustion environments, in the mid-infrared range near X = 4.85 μm at typical combustion temperatures (800-2500 K) and pressures (1-3 atm). All of this is possible through the exploitation of chirp in a quantum cascade laser, operating at a duty cycle of 50%, and by using high bandwidth (500 MHz) photodetection. Here, we showcase uncluttered, spectrally-pure Voigt profile fitting with accompanying peak SNRs of 150, resulting in a typical temperature precision of 0.9% (1u) at an effective time-resolution of 1.0 MHz. Our sensor is applicable to other species, and canbe integrated into commercial technologies.
Banks, H T; Birch, Malcolm J; Brewin, Mark P; Greenwald, Stephen E; Hu, Shuhua; Kenz, Zackary R; Kruse, Carola; Maischak, Matthias; Shaw, Simon; Whiteman, John R
2014-04-13
We revisit a method originally introduced by Werder et al. (in Comput. Methods Appl. Mech. Engrg., 190:6685-6708, 2001) for temporally discontinuous Galerkin FEMs applied to a parabolic partial differential equation. In that approach, block systems arise because of the coupling of the spatial systems through inner products of the temporal basis functions. If the spatial finite element space is of dimension D and polynomials of degree r are used in time, the block system has dimension ( r + 1) D and is usually regarded as being too large when r > 1. Werder et al. found that the space-time coupling matrices are diagonalizable over [Formula: see text] for r ⩽ 100, and this means that the time-coupled computations within a time step can actually be decoupled. By using either continuous Galerkin or spectral element methods in space, we apply this DG-in-time methodology, for the first time, to second-order wave equations including elastodynamics with and without Kelvin-Voigt and Maxwell-Zener viscoelasticity. An example set of numerical results is given to demonstrate the favourable effect on error and computational work of the moderately high-order (up to degree 7) temporal and spatio-temporal approximations, and we also touch on an application of this method to an ambitious problem related to the diagnosis of coronary artery disease. Copyright © 2014 The Authors. International Journal for Numerical Methods in Engineering published by John Wiley & Sons Ltd.
Pressure dependent elastic and structural (B3-B1) properties of Ga based monopnictides
International Nuclear Information System (INIS)
Varshney, Dinesh; Joshi, Geetanjali; Varshney, Meenu; Shriya, Swarna
2010-01-01
By formulating an effective interionic interaction potential that incorporates the long-range Coulomb, the covalency effects, the charge transfer caused by the deformation of the electron shells of the overlapping ions, the Hafemeister and Flygare type short-range overlap repulsion extended up to the second neighbour ions and the van der Waals (vdW) interaction, the pressure dependent elastic and thermodynamical properties of the III-V semiconductors as GaY (Y = N, P, As) are studied. The estimated values of phase transition pressure of GaY (Y = N, P, As) are in reasonably good agreement with the available data on the phase transition pressures (P t = 41, 22, 17 GPa). The vast volume discontinuity in pressure-volume phase diagram identifies a structural phase transition from zinc-blende (B3) to rock salt (B1) structure. Later on, the Poisson's ratio ν, the ratio R S/B of S (Voigt averaged shear modulus) over B (bulk modulus), elastic anisotropy parameter, elastic wave velocity, average wave velocity and Debye temperature as functions of pressure is calculated. From Poisson's ratio and the ratio R S/B it is inferred that GaY (Y = N, P, As) is brittle [ductile] in zinc-blende (B3) [Sodium Chloride (B1)] phase. To our knowledge this is the first quantitative theoretical prediction of the pressure dependence of ductile (brittle) nature of GaY compounds and still awaits experimental confirmations.
How preservation time changes the linear viscoelastic properties of porcine liver.
Wex, C; Stoll, A; Fröhlich, M; Arndt, S; Lippert, H
2013-01-01
The preservation time of a liver graft is one of the crucial factors for the success of a liver transplantation. Grafts are kept in a preservation solution to delay cell destruction and cellular edema and to maximize organ function after transplantation. However, longer preservation times are not always avoidable. In this paper we focus on the mechanical changes of porcine liver with increasing preservation time, in order to establish an indicator for the quality of a liver graft dependent on preservation time. A time interval of 26 h was covered and the rheological properties of liver tissue studied using a stress-controlled rheometer. For samples of 1 h preservation time 0.8% strain was found as the limit of linear viscoelasticity. With increasing preservation time a decrease in the complex shear modulus as an indicator for stiffness was observed for the frequency range from 0.1 to 10 Hz. A simple fractional derivative representation of the Kelvin Voigt model was applied to gain further information about the changes of the mechanical properties of liver with increasing preservation time. Within the small shear rate interval of 0.0001-0.01 s⁻¹ the liver showed Newtonian-like flow behavior.
Fornacelli, Cristina; Ceglia, Andrea; Bracci, Susanna; Vilarigues, Marcia
2018-01-01
In the last decades the speciation of the cobalt complex in a glass matrix has been extensively studied. Bivalent cobalt ions in glasses of different composition commonly adopt a tetrahedral coordination, though hexa- or penta-coordinated species are also possible. Changes in the absorbance spectrum of Co-doped glasses were attested in previous studies according to the introduction of different modifying cations. A shifting of the first sub-band characterizing the typical triplets of tetrahedral Co2 + ions in both the visible and near infrared regions was observed, but discrepancies in literature suggested a relevant role of glass composition on the definition of the optical signature of cobalt. Co-doped glasses with different composition (soda-lime, potash-lime, mixed alkali and ZnO-Na2O-CaO-SiO2) were studied via Fiber Optic Reflectance Spectroscopy (FORS). Pseudo-Voigt functions were used for the deconvolution of the absorbance spectra and the features of the bands characteristic of each cobalt complex were investigated. The structural role played by each modifying cation and the fundamental implications of glass basicity on the speciation of different Co-complexes were stressed. Changes in glass structure resulted in different equilibria between the three absorbing species whose specific optical signatures in the 480-530 nm region interact to determine the resulting absorbance spectrum.
International Nuclear Information System (INIS)
Yoneda, A; Sohag, F H
2010-01-01
The bulk physical properties of composite systems are difficult to predict - even when the properties of the constituent materials in the system are well known. We conducted a finite-element method simulation to examine the inclusion effect by substituting an inclusion phase (second phase) into a host phase (first phase). We have organized the simulation results as a function of the elasticity of host and inclusion phases. In this procedure, special attention was paid to the initial change of elastic constants as the inclusion volume ratio was varied. To accomplish this, we introduced a new parameter D ij defined as the derivatives of the normalized stiffness elastic constant over the inclusion volume ratio. We succeeded in obtaining useful systematic formulations for D ij . These formulations are expected to be applicable to the study of composite systems in many disciplines, such as geophysics, mechanics, material engineering, and biology. The present results provide much more effective constraints on the physical properties of composite systems, like rocks, than traditional methods, such as the Voigt-Reuss bounds.
The influence of texture on the strain measured by diffraction
International Nuclear Information System (INIS)
Penning, P.; Brakman, C.M.
1988-01-01
Strain, as determined by diffraction techniques, is calculated from its constituents. First, the fraction of the crystals that have the proper orientation for diffraction. One degree of freedom is present: the angle of rotation φ 2 '' about the scattering vector that the diffracting crystals have in common. The proper orientations, expressed in Euler angles, lie on a line ('trace') in orientation space. The density along the trace is asserted to be known as a Fourier series in φ 2 ''. Second, the strain in the diffracting crystals. The simplest possible models are discussed: the Voigt and Reuss approximations. The symmetries of the crystal (m3 or m3m) and of the orientation distribution function (o.d.f.) are taken into account. The dilatation in spacing of the reflecting planes is found as a Fourier series in φ 2 '' also. Only the zeroth, first and second harmonic (including phase angles: five parameters) play a part. The diffraction strain is the average over the angle φ 2 '' of the dilatation, weighted with the product of the orientation density and the square of the structure factor. For each contributing trace, the corresponding Fourier coefficients have to be multiplied and added to obtain the diffraction strain. The symmetry of the diffraction pole figure is derived. (orig.)
Soft inclusion in a confined fluctuating active gel
Singh Vishen, Amit; Rupprecht, J.-F.; Shivashankar, G. V.; Prost, J.; Rao, Madan
2018-03-01
We study stochastic dynamics of a point and extended inclusion within a one-dimensional confined active viscoelastic gel. We show that the dynamics of a point inclusion can be described by a Langevin equation with a confining potential and multiplicative noise. Using a systematic adiabatic elimination over the fast variables, we arrive at an overdamped equation with a proper definition of the multiplicative noise. To highlight various features and to appeal to different biological contexts, we treat the inclusion in turn as a rigid extended element, an elastic element, and a viscoelastic (Kelvin-Voigt) element. The dynamics for the shape and position of the extended inclusion can be described by coupled Langevin equations. Deriving exact expressions for the corresponding steady-state probability distributions, we find that the active noise induces an attraction to the edges of the confining domain. In the presence of a competing centering force, we find that the shape of the probability distribution exhibits a sharp transition upon varying the amplitude of the active noise. Our results could help understanding the positioning and deformability of biological inclusions, e.g., organelles in cells, or nucleus and cells within tissues.
First line shape analysis and spectroscopic parameters for the ν11 band of 12C2H4
Es-sebbar, Et-touhami; Mantzaras, John; Benilan, Yves; Farooq, Aamir
2016-01-01
An accurate knowledge of line intensities, collisional broadening coefficients and narrowing parameters is necessary for the interpretation of high-resolution infrared spectra of the Earth and other planetary atmospheres. One of the most promising spectral domains for (C2H4)-C-12 monitoring in such environments is located near the 336 gm window, through its v(11) C-H stretching mode. In this paper, we report an extensive study in which we precisely determine spectroscopic parameters of (C2H4)-C-12 v(11) band at 297 +/- 1 K, using a narrow Difference-Frequency-Generation (DFG) laser with 10(-4) cm(-1) resolution. Absorption measurements were performed in the 2975-2980 cm(-1) spectral window to investigate 32 lines corresponding to where, J'ka',kc'<- Jka,kc, 5 <= J <= 7; 0.5 <= K-a <= 6 and 1 <= K-c <= 14. Spectroscopic parameters are retrieved using either Voigt or appropriate Galatry profile to simulate the measured (C2H4)-C-12 line shape. Line intensities along with self-broadening coefficients are reported for all lines. Narrowing coefficients for each isolated line are also derived. To our knowledge, the current study reports the first extensive spectroscopic parameter measurements of the (C2H4)-C-12 v(11) band in the 2975-2980 cm(-1) range. (C) 2016 Elsevier Ltd. All rights reserved.
LipSpin: A New Bioinformatics Tool for Quantitative 1H NMR Lipid Profiling.
Barrilero, Rubén; Gil, Miriam; Amigó, Núria; Dias, Cintia B; Wood, Lisa G; Garg, Manohar L; Ribalta, Josep; Heras, Mercedes; Vinaixa, Maria; Correig, Xavier
2018-02-06
The structural similarity among lipid species and the low sensitivity and spectral resolution of nuclear magnetic resonance (NMR) have traditionally hampered the routine use of 1 H NMR lipid profiling of complex biological samples in metabolomics, which remains mostly manual and lacks freely available bioinformatics tools. However, 1 H NMR lipid profiling provides fast quantitative screening of major lipid classes (fatty acids, glycerolipids, phospholipids, and sterols) and some individual species and has been used in several clinical and nutritional studies, leading to improved risk prediction models. In this Article, we present LipSpin, a free and open-source bioinformatics tool for quantitative 1 H NMR lipid profiling. LipSpin implements a constrained line shape fitting algorithm based on voigt profiles and spectral templates from spectra of lipid standards, which automates the analysis of severely overlapped spectral regions and lipid signals with complex coupling patterns. LipSpin provides the most detailed quantification of fatty acid families and choline phospholipids in serum lipid samples by 1 H NMR to date. Moreover, analytical and clinical results using LipSpin quantifications conform with other techniques commonly used for lipid analysis.
Goodarzi, Mohammad Saeed; Hosseini-Toudeshky, Hossein
2017-11-01
In this paper a formulation of a viscoelastic-damage interface model with friction in mode-II is presented. The cohesive constitutive law contains elastic and damage regimes. It has been assumed that the shear stress in the elastic regime follows the viscoelastic properties of the matrix material. The three element Voigt model has been used for the formulation of relaxation modulus of the material. Damage evolution proceeds according to the bilinear cohesive constitutive law combined with friction stress consideration. Combination of damage and friction is based on the presumption that the damaged area, related to an integration point, can be dismembered into the un-cracked area with the cohesive damage and cracked area with friction. Samples of a one element model have been presented to see the effect of parameters on the cohesive constitutive law. A comparison between the predicted results with available results of end-notched flexure specimens in the literature is also presented to verify the model. Transverse crack tension specimens are also simulated for different applied displacement velocities.
Energy Technology Data Exchange (ETDEWEB)
Bouhemadou, A., E-mail: a_bouhemadou@yahoo.fr [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Haddadi, K. [Laboratory for Developing New Materials and their Characterization, Department of Physics, Faculty of Science, University of Setif, 19000 Setif (Algeria); Khenata, R. [Laboratoire de Physique Quantique et de Modelisation Mathematique (LPQ3M), Departement de Technologie, Universite de Mascara, 29000 Mascara (Algeria); Rached, D. [Department of Physics, Faculty of Science, University of Sidi-Bel-Abbes, 22000 (Algeria); Bin-Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia)
2012-06-15
A density functional-based method is used to investigate the structural, elastic and thermodynamic properties of the cubic spinel semiconductors MgIn{sub 2}S{sub 4} and CdIn{sub 2}S{sub 4} at different pressures and temperatures. Computed ground structural parameters are in good agreement with the available experimental data. Single-crystal elastic parameters are calculated for pressure up to 10 GPa and temperature up to 1200 K. The obtained elastic constants values satisfy the requirement of mechanical stability, indicating that MgIn{sub 2}S{sub 4} and CdIn{sub 2}S{sub 4} compounds could be stable in the investigated pressure range. Isotropic elastic parameters for ideal polycrystalline MgIn{sub 2}S{sub 4} and CdIn{sub 2}S{sub 4} aggregates are computed in the framework of the Voigt-Reuss-Hill approximation. Pressure and thermal effects on some macroscopic properties such as lattice constant, volume expansion coefficient and heat capacities are predicted using the quasi-harmonic Debye model in which the lattice vibrations are taken into account.
Directory of Open Access Journals (Sweden)
Esfandiar, H.
2013-05-01
Full Text Available In this paper, based on the VoigtKelvin constitutive model, nonlinear dynamic modelling and state space representation of a viscoelastic beam acting as a flexible robotic manipulator is investigated. Complete nonlinear dynamic modelling of a viscoelastic beam without premature linearisation of dynamic equations is developed. The adopted method is capable of reproducing nonlinear dynamic effects, such as beam stiffening due to centrifugal and Coriolis forces induced by rotation of the joints. Structural damping effects on the models dynamic behaviour are also shown. A reliable model for a viscoelastic beam is subsequently presented. The governing equations of motion are derived using Hamiltons principle, and using the finite difference method, nonlinear partial differential equations are reduced to ordinary differential equations. For the purpose of flexible manipulator control, the standard form of state space equations for the viscoelastic link and the actuator is obtained. Simulation results indicate substantial improvements in dynamic behaviour, and a parameter sensitivity study is carried out to investigate the effect of structural damping on the vibration amplitude.
Ngo, N. H.; Nguyen, H. T.; Tran, H.
2018-03-01
In this work, we show that precise predictions of the shapes of H2O rovibrational lines broadened by N2, over a wide pressure range, can be made using simulations corrected by a single measurement. For that, we use the partially-correlated speed-dependent Keilson-Storer (pcsdKS) model whose parameters are deduced from molecular dynamics simulations and semi-classical calculations. This model takes into account the collision-induced velocity-changes effects, the speed dependences of the collisional line width and shift as well as the correlation between velocity and internal-state changes. For each considered transition, the model is corrected by using a parameter deduced from its broadening coefficient measured for a single pressure. The corrected-pcsdKS model is then used to simulate spectra for a wide pressure range. Direct comparisons of the corrected-pcsdKS calculated and measured spectra of 5 rovibrational lines of H2O for various pressures, from 0.1 to 1.2 atm, show very good agreements. Their maximum differences are in most cases well below 1%, much smaller than residuals obtained when fitting the measurements with the Voigt line shape. This shows that the present procedure can be used to predict H2O line shapes for various pressure conditions and thus the simulated spectra can be used to deduce the refined line-shape parameters to complete spectroscopic databases, in the absence of relevant experimental values.
Energy Technology Data Exchange (ETDEWEB)
Bergstroem, J.
1986-01-01
The surface residual stress behaviour during fatigue of the quenched and tempered medium strength low-alloyed steel SS 2244-05, equivalent to AISI 4140, has been investigated. Notched specimens of shot peened and ground surface conditions were used. The residual stresses were measured by the X-ray diffraction sin/sup 2/psi-method at intervals in the fatigue tests. Fatigue testing was performed with constant load amplitude at nominal pull-push and pull-pull cycling. The effects of peak-load and variable amplitude were also examined. It was found that the residual stress relaxation could be linked to a total mean stress relaxation towards zero, to an extent which is ruled by a softening criteria. Fatigue test data of the shot peened and ground surface conditions are also given. An X-ray diffraction line broadening analysis was undertaken to examine the microstructural behaviour due to fatigue loading and its correlation to the residual stress behaviour. Single-peak analysis with a Voigt-function method was used to estimate the microstructural parameters, domain size and microstrain. Multiple-peak analysis according to the Warren-Averbach method was used to verify the single-peak analysis. The dislocation density was found to decrease depending on the load amplitude, while the dislocation arrangement follows a pattern depending on yield history.
Radiation trapping in atomic absorption spectroscopy at lead determination in different matricies
International Nuclear Information System (INIS)
El-Gohary, Z.
2005-01-01
The determination of lead by flame atomic absorption analysis in the presence of Sn and Fe atoms and different matrices such as OH and SO 3 was investigated with the objective of understanding the spectral interference processes at the analytical lines 283.31 nm for a wide range of concentration. The radiation trapping factor was interpreted and evaluated assuming Voigt distribution of the atomic and rotational lines in the flame. The radiation trapping factor was increased by increasing the number density (plasma of the absorbing medium is optically thick). In plasma, there is a certain point of equilibrium between the trapping and the escaping of radiation, which is relevant to 50% of absorption. The spectral background interference can cause a variation of the number density at equilibrium point as a result of the degree of overlap with the analytical line. The spectral background interference can be easily avoided by using another resonance absorption line for the analysis. The chemical modification of the matrix is applied to minimize the interference effect. Nitric acid, ammonium nitrate and magnesium nitrate are most commonly recommended as matrix modifiers
Local buckling of composite channel columns
Szymczak, Czesław; Kujawa, Marcin
2018-05-01
The investigation concerns local buckling of compressed flanges of axially compressed composite channel columns. Cooperation of the member flange and web is taken into account here. The buckling mode of the member flange is defined by rotation angle a flange about the line of its connection with the web. The channel column under investigation is made of unidirectional fibre-reinforced laminate. Two approaches to member orthotropic material modelling are performed: the homogenization with the aid of theory of mixture and periodicity cell or homogenization upon the Voigt-Reuss hypothesis. The fundamental differential equation of local buckling is derived with the aid of the stationary total potential energy principle. The critical buckling stress corresponding to a number of buckling half-waves is assumed to be a minimum eigenvalue of the equation. Some numerical examples dealing with columns are given here. The analytical results are compared with the finite element stability analysis carried out by means of ABAQUS software. The paper is focused on a close analytical solution of the critical buckling stress and the associated buckling mode while the web-flange cooperation is assumed.
The Biot coefficient for a low permeability heterogeneous limestone
Selvadurai, A. P. S.
2018-04-01
This paper presents the experimental and theoretical developments used to estimate the Biot coefficient for the heterogeneous Cobourg Limestone, which is characterized by its very low permeability. The coefficient forms an important component of the Biot poroelastic model that is used to examine coupled hydro-mechanical and thermo-hydro-mechanical processes in the fluid-saturated Cobourg Limestone. The constraints imposed by both the heterogeneous fabric and its extremely low intact permeability [K \\in (10^{-23},10^{-20}) m2 ] require the development of alternative approaches to estimate the Biot coefficient. Large specimen bench-scale triaxial tests (150 mm diameter and 300 mm long) that account for the scale of the heterogeneous fabric are complemented by results for the volume fraction-based mineralogical composition derived from XRD measurements. The compressibility of the solid phase is based on theoretical developments proposed in the mechanics of multi-phasic elastic materials. An appeal to the theory of multi-phasic elastic solids is the only feasible approach for examining the compressibility of the solid phase. The presence of a number of mineral species necessitates the use of the theories of Voigt, Reuss and Hill along with the theories proposed by Hashin and Shtrikman for developing bounds for the compressibility of the multi-phasic geologic material composing the skeletal fabric. The analytical estimates for the Biot coefficient for the Cobourg Limestone are compared with results for similar low permeability rocks reported in the literature.
Energy Technology Data Exchange (ETDEWEB)
Wang, Zhuqing [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States); Stoica, Alexandru D. [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Ma, Dong, E-mail: dongma@ornl.gov [Chemical and Engineering Materials Division, Neutron Sciences Directorate, Oak Ridge National Laboratory, Oak Ridge, TN 37831 (United States); Beese, Allison M., E-mail: amb961@psu.edu [Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA 16802 (United States)
2016-09-30
In this work, diffraction and single-crystal elastic constants of Inconel 625 have been determined by means of in situ loading at room and elevated temperatures using time-of-flight neutron diffraction. Theoretical models proposed by Voigt, Reuss, and Kroner were used to determine single-crystal elastic constants from measured diffraction elastic constants, with the Kroner model having the best ability to capture experimental data. The magnitude of single-crystal elastic moduli, computed from single-crystal elastic constants, decreases and the single crystal anisotropy increases as temperature increases, indicating the importance of texture in affecting macroscopic stress at elevated temperatures. The experimental data reported here are of great importance in understanding additive manufacturing of metallic components as: diffraction elastic constants are required for computing residual stresses from residual lattice strains measured using neutron diffraction, which can be used to validate thermomechanical models of additive manufacturing, while single-crystal elastic constants can be used in crystal plasticity modeling, for example, to understand mechanical deformation behavior of additively manufactured components.
Dual-Comb Spectroscopy of the ν_1+ ν_3 Band of Acetylene: Intensity and Transition Dipole Moment
Iwakuni, Kana; Okubo, Sho; Yamada, Koichi MT; Inaba, Hajime; Onae, Atsushi; Hong, Feng-Lei; Sasada, Hiroyuki
2017-06-01
The ν_1+ν_3 vibration band of ^{12}C_2H_2 is recorded with a homemade dual-comb spectrometer. The spectral resolution and the accuracy of frequency determination are high, and the bandwidth is broad enough to take spectrum of the whole band in one shot. The last remarkable competence enables us to record all the spectral lines under constant experimental conditions. The linewidth and line strength of the P(26) to R(29) transitions are determined by fitting the line profile to Lambert-Beer's law with a Voigt function. In the course of analysis, we found the ortho-para dependence of the pressure-broadening coefficient. This time, we have determined the transition dipole moment of the ν_1+ν_3 band. It is noted that the transition dipole moment determined from the ortho lines agrees with that from the para lines. S. Okubo et al., Applied Physics Express 8, 082402 (2015). K.Iwakuni et al., 71th ISMS, WK15 K. Iwakuni et al., Physical Review Letters 117, 143902 (2016).
Energy Technology Data Exchange (ETDEWEB)
Guzmán, Andrés E.; Garay, Guido; Bronfman, Leonardo; Mardones, Diego [Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago (Chile); Rodríguez, Luis F. [Centro de Radioastronomía y Astrofísica (UNAM), Morelia 58089 (Mexico); Moran, James [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA (United States); Brooks, Kate J. [CSIRO Astronomy and Space Science, P.O. Box 76, Epping, 1710 NSW (Australia); Nyman, Lars-Åke [Joint ALMA Observatory (JAO), Alonso de Córdova 3107, Vitacura, Santiago (Chile); Sanhueza, Patricio [Institute for Astrophysical Research, Boston University, Boston, MA 02215 (United States)
2014-12-01
We report the detection, made using ALMA, of the 92 GHz continuum and hydrogen recombination lines (HRLs) H40α, H42α, and H50β emission toward the ionized wind associated with the high-mass young stellar object G345.4938+01.4677. This is the luminous central dominating source located in the massive and dense molecular clump associated with IRAS 16562–3959. The HRLs exhibit Voigt profiles, which is a strong signature of Stark broadening. We successfully reproduce the observed continuum and HRLs simultaneously using a simple model of a slow ionized wind in local thermodynamic equilibrium, with no need for a high-velocity component. The Lorentzian line wings imply electron densities of 5 × 10{sup 7} cm{sup –3} on average. In addition, we detect SO and SO{sub 2} emission arising from a compact (∼3000 AU) molecular core associated with the central young star. The molecular core exhibits a velocity gradient that is perpendicular to the jet-axis, which we interpret as evidence of rotation. The set of observations toward G345.4938+01.4677 are consistent with it being a young high-mass star associated with a slow photo-ionized wind.
Fluid-structure interaction with pipe-wall viscoelasticity during water hammer
Keramat, A.; Tijsseling, A. S.; Hou, Q.; Ahmadi, A.
2012-01-01
Fluid-structure interaction (FSI) due to water hammer in a pipeline which has viscoelastic wall behaviour is studied. Appropriate governing equations are derived and numerically solved. In the numerical implementation of the hydraulic and structural equations, viscoelasticity is incorporated using the Kelvin-Voigt mechanical model. The equations are solved by two different approaches, namely the Method of Characteristics-Finite Element Method (MOC-FEM) and full MOC. In both approaches two important effects of FSI in fluid-filled pipes, namely Poisson and junction coupling, are taken into account. The study proposes a more comprehensive model for studying fluid transients in pipelines as compared to previous works, which take into account either FSI or viscoelasticity. To verify the proposed mathematical model and its numerical solutions, the following problems are investigated: axial vibration of a viscoelastic bar subjected to a step uniaxial loading, FSI in an elastic pipe, and hydraulic transients in a pressurised polyethylene pipe without FSI. The results of each case are checked with available exact and experimental results. Then, to study the simultaneous effects of FSI and viscoelasticity, which is the new element of the present research, one problem is solved by the two different numerical approaches. Both numerical methods give the same results, thus confirming the correctness of the solutions.
Wenk, H.-R.; Vasin, R. N.; Kern, H.; Matthies, S.; Vogel, S. C.; Ivankina, T. I.
2012-10-01
A sample of biotite gneiss from the Outokumpu deep drilling project in Finland was investigated by Kern et al. (2008) for crystal preferred orientation and elastic anisotropy. Considerable differences between measured acoustic velocities and velocities calculated on the basis of texture patterns were observed. Measured P-wave anisotropy was 15.1% versus a Voigt average yielding 7.9%. Here we investigate the same sample with different methods and using different averaging techniques. Analyzing time-of-flight neutron diffraction data from Dubna-SKAT and LANSCE-HIPPO diffractometers with the Rietveld technique, much stronger preferred orientation for biotite is determined, compared to conventional pole-figure analysis reported previously. The comparison reveals important differences: HIPPO has much better counting statistics but pole figure coverage is poor. SKAT has better angular resolution. Using the new preferred orientation data and applying a self-consistent averaging method that takes grain shapes into account, close agreement of calculated and measured P-wave velocities is observed (12.6%). This is further improved by adding 0.1 vol.% flat micropores parallel to the biotite platelets in the simulation (14.9%).
Biaxial experimental and analytical characterization of a dielectric elastomer
Helal, Alexander; Doumit, Marc; Shaheen, Robert
2018-01-01
Electroactive polymers (EAPs) have emerged as a strong contender for use in low-cost efficient actuators in multiple applications especially related to biomimetic and mobile-assistive devices. Dielectric elastomers (DE), a subcategory of these smart materials, have been of particular interest due to their large achievable deformation and favourable mechanical and electro-mechanical properties. Previous work has been completed to understand the behaviour of these materials; however, their properties require further investigation to properly integrate them into real-world applications. In this study, a biaxial tensile experimental evaluation of 3M™ VHB 4905 and VHB 4910 is presented with the purpose of illustrating the elastomers' transversely isotropic mechanical behaviours. These tests were applied to both tapes for equibiaxial stretch rates ranging between 0.025 and 0.300 s-1. Subsequently, a dynamic planar biaxial visco-hyperelastic constitutive relationship was derived from a Kelvin-Voigt rheological model and the general Hooke's law for transversely isotropic materials. The model was then fitted to the experimental data to obtain three general material parameters for either tapes. The model's ability to predict tensile stress response and internal energy dissipation, with respect to experimental data, is evaluated with good agreement. The model's ability to predict variations in mechanical behaviour due to changes in kinematic variables is then illustrated for different conditions.
Mondelain, D.; Vasilchenko, S.; Čermák, P.; Kassi, S.; Campargue, A.
2017-01-01
The CO2 absorption continuum near 2.3 μm is determined for a series of sub atmospheric pressures (250-750 Torr) by high sensitivity Cavity Ring Down Spectroscopy. An experimental procedure consisting in injecting successively a gas flow of CO2 and synthetic air, keeping constant the gas pressure in the CRDS cell, has been developed. This procedure insures a high stability of the spectra baseline by avoiding changes of the optical alignment due to pressure changes. The CO2 continuum was obtained as the difference between the CO2 absorption coefficient and a local lines simulation using a Voigt profile truncated at ±25 cm-1. Following the results of the preceding analysis of the CO2 rovibrational lines (Vasilchenko S et al. J Quant Spectrosc Radiat Transfer 10.1016/j.jqsrt.2016.07.002, a CO2 line list with intensities obtained by variational calculations and empirical line positions was preferred to the HITRAN line list. A quadratic pressure dependence of the absorption continuum is observed, with an average binary absorption coefficient increasing from 2 to 4×10-8 cm-1 amagat-2 between 4320 and 4380 cm-1. The obtained continuum is found in good agreement with a previous measurement using much higher densities (20 amagat) and a low resolution grating spectrograph and is consistent with values currently used in the analysis of Venus spectra.
Yang, L.; Lin, H.; Plimmer, M. D.; Feng, X. J.; Zhang, J. T.
2018-05-01
The performances of a multi-spectral fit for the spectra of pressure-broadened overlapping lines (R9F1, R9F2) of 12CH4 in binary mixtures with N2 were studied by applying different lineshape models, from the simplest Voigt profile (VP) to the Harmann-Tran profile (HTP). Line-mixing was approximated in the first order in the spectral fits. Data were acquired using a high-resolution cavity ring-down spectrometer of minimum detectable absorption coefficient of 2.8 × 10-12 cm-1. The lines were observed with a signal-to-noise ratio of 19 365 for pressures from 5 to 40 kPa. The study reveals that the multi-spectral fits using the HTP and the speed-dependent Nelkin-Ghatak profile (SDNGP) yield the best among all tested. The two models gave the maximum relative residuals of less than 0.065 %. All things considered, the HTP and the SDNGP appear to be the most reliable models for treating the present case of multi-spectral fitting of unresolved dual-component spectra.
Bioerosion and encrustation: Evidences from the Middle ‒ Upper Jurassic of central Saudi Arabia
El-Hedeny, Magdy; El-Sabbagh, Ahmed; Al Farraj, Saleh
2017-10-01
The Middle ‒ Upper Jurassic hard substrates of central Saudi Arabia displayed considerable signs of bioerosion and encrustations. They include organic (oysters, other bivalves, gastropods, corals and brachiopods) and an inorganic carbonate hardground that marks the boundary between the Middle Jurassic Tuwaiq Mountain Limestone and the Upper Jurassic Hanifa Formation. Traces of bioerosion in organic substrates include seven ichnotaxa produced by bivalves (Gastrochaenolites Leymerie, 1842), polychaete annelids (Trypanites Mägdefrau, 1932; MaeandropolydoraVoigt, 1965 and CaulostrepsisClarke, 1908), sponges (Entobia Bronn, 1837), acrothoracican cirripedes (Rogerella Saint-Seine, 1951), gastropods (Oichnus Bromley, 1981) and probable ?Centrichnus cf. eccentricus. The encrusting epifauna on these substrates consist of several organisms, including oysters, serpulid worms, corals and foraminifera. In contrast, the carbonate hardground was only bioeroded by Gastrochaenolite, Trypanites and Entobia. Epibionts on this hardground include ;Liostrea Douvillé, 1904-type; oysters, Nanogyra nana Sowerby, 1822 and serpulids. In general, bioerosion and encrustation are less diversified in hardground than in organic substrates, indicating a long time of exposition of organic substrates with slow to moderate rate of deposition in a restricted marine environment. Both organic and inorganic commuinities are correlated with those of other equatorial, subtropical and temperate equivalents.
Salem, Jamel; Blanquet, Ghislain; Lepère, Muriel; Younes, Rached ben
2018-05-01
The broadening, shifting and mixing coefficients of the doublet spectral lines in the ν2 and ν4 bands of PH3 perturbed by H2 have been determined at room temperature. Indeed, the collisional spectroscopic parameters: intensities, line widths, line shifts and line mixing parameters, are all grouped together in the collisional relaxation matrix. To analyse the collisional process and physical effects on spectra of phosphine (PH3), we have used the measurements carried out using a tunable diode-laser spectrometer in the ν2 and ν4 bands of PH3 perturbed by hydrogen (H2) at room temperature. The recorded spectra are fitted by the Voigt profile and the speed-dependent uncorrelated hard collision model of Rautian and Sobelman. These profiles are developed in the studies of isolated lines and are modified to account for the line mixing effects in the overlapping lines. The line widths, line shifts and line mixing parameters are given for six A1 and A2 doublet lines with quantum numbers K = 3n, (n = 1, 2, …) and overlapped by collisional broadening at pressures of less than 50 mbar.
Kyutt, R. N.
2018-04-01
The three-wave X-ray diffraction in strongly disordered epitaxial layers of GaN and ZnO is experimentally investigated. The charts of the intensity distribution in the reciprocal space are plotted in coordinates q θ and q ϕ for the most intensive three-wave combination (1010)/(1011) by means of subsequent θ- and ϕ-scanning. A nontrivial shape of the θ-sections of these contours at a distance from the ϕ center of reflection is revealed; it is different for different samples. For the θ-curves at the center of reflection, we observed a common peak that may be approximated by the Voigt function with a power-low decrease in the intensity at the wings; the decrease law (from-4.5 to-5.0) is found to be considerably greater than that for the similar curves of two-wave diffraction and not depending on the dislocation density and distribution in layers. In some films we observed a coarse-block structure; in addition, it follows from the distribution in the reciprocal space that these blocks are turned with respect to each other around a normal to the surface, which allows us to suggest the existence of low-angle boundaries between them, consisting exclusively of edge dislocations.
Owen, Kyle
2013-05-01
Laser-based ammonia gas sensors have useful applications in many fields including combustion, atmospheric monitoring, and medical diagnostics. Calibration-free trace gas sensors require the spectroscopic parameters including linestrengths and collisional broadening coefficients to be known. Ammonia\\'s strong ν2 vibrational band between 9 - 12 μm has the high absorption strength needed for sensing small concentrations. Within this band, the 1103.46cm-1 feature is one of the strongest and has minimal interference from CO2 and H2O. However, the six rotational transitions that make up this feature have not been studied previously with absorption spectroscopy due to their small line spacing ranging from 0.004 to 0.029cm-1. A tunable quantum cascade laser was used to accurately study these six transitions. A retrieval program was used to determine the linestrengths and collisional broadening coefficients based on Voigt and Galatry profiles. The experiments were performed with ammonia mixtures in nitrogen, oxygen, water vapor, and carbon dioxide at room temperature in an optical cell. These data are going to aid in the development of quantitative ammonia sensors utilizing this strong absorption feature. © 2013 Elsevier Ltd.
Soltanpour, Mohsen; Samsami, Farzin
2011-03-01
The objective of this paper is to investigate the rheological behavior of kaolinite and Hendijan mud, located at the northwest part of the Persian Gulf, and the dissipative role of this muddy bed on surface water waves. A series of laboratory rheological tests was conducted to investigate the rheological response of mud to rotary and cyclic shear rates. While a viscoplastic Bingham model can successfully be applied for continuous controlled shear-stress tests, the rheology of fluid mud displays complex viscoelastic behavior in time-periodic motion. The comparisons of the behavior of natural Hendijan mud with commercial kaolinite show rheological similarities. A large number of laboratory wave-flume experiments were carried out with a focus on the dissipative role of the fluid mud. Assuming four rheological models of viscous, Kelvin-Voigt viscoelastic, Bingham viscoplastic, and viscoelastic-plastic for fluid mud layer, a numerical multi-layered model was applied to analyze the effects of different parameters of surface wave and muddy bed on wave attenuation. The predicted results based on different rheological models generally agree with the obtained wave-flume data implying that the adopted rheological model does not play an important role in the accuracy of prediction.
Cyprych, Daria; Piazolo, Sandra; Almqvist, Bjarne S. G.
2017-11-01
We present calculated seismic velocities and anisotropies of mafic granulites and eclogites from the Cretaceous deep lower crust (∼40-65 km) of Fiordland, New Zealand. Both rock types show a distinct foliation defined by cm-scale compositional banding. Seismic properties are estimated using the Asymptotic Expansion Homogenisation - Finite Element (AEH-FE) method that, unlike the commonly used Voigt-Reuss-Hill homogenisation, incorporates the phase boundary network into calculations. The predicted mean P- and S-wave velocities are consistent with previously published data for similar lithologies from other locations (e.g., Kohistan Arc), although we find higher than expected anisotropies (AVP ∼ 5.0-8.0%, AVS ∼ 3.0-6.5%) and substantial S-wave splitting along foliation planes in granulites. This seismic signature of granulites results from a density and elasticity contrast between cm-scale pyroxene ± garnet stringers and plagioclase matrix rather than from crystallographic orientations alone. Banded eclogites do not show elevated anisotropies as the contrast in density and elastic constants of garnet and pyroxene is too small. The origin of compositional banding in Fiordland granulites is primarily magmatic and structures described here are expected to be typical for the base of present day magmatic arcs. Hence, we identify a new potential source of anisotropy within this geotectonic setting.
International Nuclear Information System (INIS)
Liu Qijun; Liu Zhengtang; Feng Liping; Tian Hao
2010-01-01
We have performed ab-initio total energy calculations using the plane-wave ultrasoft pseudopotential technique based on the first-principles density-functional theory (DFT) to study structural parameters, mechanical, electronic, chemical bonding and optical properties of cubic BaHfO 3 . The calculated lattice parameter and independent elastic constants are in good agreement with previous theoretical and experimental work. The bulk, shear and Young's modulus, Poisson coefficient, compressibility and Lame constants are obtained using Voigt-Reuss-Hill method and the Debye temperature is estimated using Debye-Grueneisen model, which are consistent with previous results. Electronic and chemical bonding properties have been studied from the calculations of band structure, density of states and charge densities. Furthermore, in order to clarify the mechanism of optical transitions of cubic BaHfO 3 , the complex dielectric function, refractive index, extinction coefficient, reflectivity, absorption efficient, loss function and complex conductivity function are calculated. Then, we have explained the origins of spectral peaks on the basis of the theory of crystal-field and molecular-orbital bonding.
Changes in the state of heat-resistant steel induced by repeated hot deformation
Lyubimova, Lyudmila L.; Fisenko, Roman N.; Tashlykov, Alexander A.; Tabakaev, Roman B.
2018-01-01
This work deals with the problems of structural regeneration by thermal restoration treatment (TRT). These include the lack of a structural sign showing that TRT is possible, a consensus on TRT modes, the data on the necessary relaxation depth of residual stresses, or criteria of structural restoration. Performing a TRT without solving these problems may deteriorate the properties of steel or even accelerate its destruction. With this in view, the purpose of this work is to determine experimentally how the residual stress state changes under thermal and mechanical loads in order to specify the signs of the restoration of structure and structural stability. The object of this research is unused 12Cr1MoV steel that has been aged naturally for 13 years. Using X-ray dosimetry with X-ray spectral analysis, we study the distribution of internal residual stresses of the first kind during the repeated hot deformation. After repeated thermal deformation, the sample under study transforms from a viscoelastic Maxwell material into a Kelvin-Voigt material, which facilitates structural stabilization. A sign of this is the relaxation limit increase, prevention of continuous decay of an α-solid solution of iron and restoration of the lattice parameter.
International Nuclear Information System (INIS)
Kochanov, R.V.; Gordon, I.E.; Rothman, L.S.; Wcisło, P.; Hill, C.; Wilzewski, J.S.
2016-01-01
The HITRAN Application Programming Interface (HAPI) is presented. HAPI is a free Python library, which extends the capabilities of the HITRANonline interface ( (www.hitran.org)) and can be used to filter and process the structured spectroscopic data. HAPI incorporates a set of tools for spectra simulation accounting for the temperature, pressure, optical path length, and instrument properties. HAPI is aimed to facilitate the spectroscopic data analysis and the spectra simulation based on the line-by-line data, such as from the HITRAN database [JQSRT (2013) 130, 4–50], allowing the usage of the non-Voigt line profile parameters, custom temperature and pressure dependences, and partition sums. The HAPI functions allow the user to control the spectra simulation and data filtering process via a set of the function parameters. HAPI can be obtained at its homepage (www.hitran.org/hapi). - Highlights: • HAPI extends the HITRANonline portal and provides an access to the HITRAN data. • Free, flexible, and portable Python library for working with the spectroscopic data. • Incorporates functions for querying, filtering and processing the spectroscopic data. • Provides functionality for single-layer spectra simulation. • Can be used in the radiative transfer codes, spectroscopic data validation, etc.
Zeeman spectroscopy of Zn-H complex in germanium
International Nuclear Information System (INIS)
Prabakar, J.P.C.; Vickers, R.E.M.; Fisher, P.
1998-01-01
Full text: A divalent substitutional zinc atom in germanium complexed with an interstitial hydrogen atom gives rise to a monovalent acceptor of trigonal symmetry. The axial nature of this complex splits the four-fold degenerate states associated with substitutional point defects into two two-fold degenerate states. Zeeman spectra of the Zn-H complex have been observed for B along and crystallographic directions in the Voigt configuration using linearly polarised radiation. Spectra of the C and D lines for B ≤ 2 Tesla are essentially identical to those of these lines of group III impurities; here B is the field strength. At all fields, splitting of the excited state of the D lines is identical to that for group III acceptors in germanium. The magnetic field dependence of the D components for both E parallel B and E perpendicular B and the selection rules demand that only one of the two two-fold 1s-like energy levels is occupied at the temperatures used instead of both. The results confirm piezospectroscopic studies which demonstrated that the axes of the complexes are along the four covalent bond directions of the host
Nanocrystalline CsPbBr3 thin films: a grain boundary opto-electronic study
Conte, G.; Somma, F.; Nikl, M.
2005-01-01
CsPbBr3 thin films with nanocrystalline morphology were studied by using optoelectronic techniques to infer the grain boundary region in respect of the crystallite's interior performance. Co-evaporation of puri-fied powders or crushed Bridgman single crystals were used to deposit materials and compare recombina-tion mechanism and dielectric relaxation processes within them. Nanosecond photoconduction decay was observed on both materials as well as activated hopping transport. An asymmetric Debye-like peak was evaluated from impedance spectroscopy with a FWHM value, which remains constant for 1.25 +/- 0.02 deca-des, addressing the presence of a tight conductivity relaxation times distribution. The evaluated activation energy, equal to 0.72 +/- 0.05 eV, similar to that estimated by DC measurements, is well smaller then that expected for an intrinsic material with exciton absorption at 2.36 eV. A simple model based on Voigt's elements was used to model the electronic characteristics of these nanostructured materials, to discuss observed results and define the role played by grain boundaries.
Chaos Suppression in Fractional order Permanent Magnet Synchronous Generator in Wind Turbine Systems
Rajagopal, Karthikeyan; Karthikeyan, Anitha; Duraisamy, Prakash
2017-06-01
In this paper we investigate the control of three-dimensional non-autonomous fractional-order uncertain model of a permanent magnet synchronous generator (PMSG) via a adaptive control technique. We derive a dimensionless fractional order model of the PMSM from the integer order presented in the literatures. Various dynamic properties of the fractional order model like eigen values, Lyapunov exponents, bifurcation and bicoherence are investigated. The system chaotic behavior for various orders of fractional calculus are presented. An adaptive controller is derived to suppress the chaotic oscillations of the fractional order model. As the direct Lyapunov stability analysis of the robust controller is difficult for a fractional order first derivative, we have derived a new lemma to analyze the stability of the system. Numerical simulations of the proposed chaos suppression methodology are given to prove the analytical results derived through which we show that for the derived adaptive controller and the parameter update law, the origin of the system for any bounded initial conditions is asymptotically stable.
An inducible tool for random mutagenesis in Aspergillus niger based on the transposon Vader.
Paun, Linda; Nitsche, Benjamin; Homan, Tim; Ram, Arthur F; Kempken, Frank
2016-07-01
The ascomycete Aspergillus niger is widely used in the biotechnology, for instance in producing most of the world's citric acid. It is also known as a major food and feed contaminant. While generation of gene knockouts for functional genomics has become feasible in ku70 mutants, analyzing gene functions or metabolic pathways remains a laborious task. An unbiased transposon-based mutagenesis approach may aid this process of analyzing gene functions by providing mutant libraries in a short time. The Vader transposon is a non-autonomous DNA-transposon, which is activated by the homologous tan1-transposase. However, in the most commonly used lab strain of A. niger (N400 strain and derivatives), we found that the transposase, encoded by the tan1 gene, is mutated and inactive. To establish a Vader transposon-based mutagenesis system in the N400 background, we expressed the functional transposase of A. niger strain CBS 513.88 under the control of an inducible promoter based on the Tet-on system, which is activated in the presence of the antibiotic doxycycline (DOX). Increasing amounts of doxycycline lead to higher Vader excision frequencies, whereas little to none activity of Vader was observed without addition of doxycycline. Hence, this system appears to be suitable for producing stable mutants in the A. niger N400 background.
Lim, Nicholas R; Shohayeb, Belal; Zaytseva, Olga; Mitchell, Naomi; Millard, S Sean; Ng, Dominic C H; Quinn, Leonie M
2017-07-11
The second most commonly mutated gene in primary microcephaly (MCPH) patients is wd40-repeat protein 62 (wdr62), but the relative contribution of WDR62 function to the growth of major brain lineages is unknown. Here, we use Drosophila models to dissect lineage-specific WDR62 function(s). Interestingly, although neural stem cell (neuroblast)-specific depletion of WDR62 significantly decreased neuroblast number, brain size was unchanged. In contrast, glial lineage-specific WDR62 depletion significantly decreased brain volume. Moreover, loss of function in glia not only decreased the glial population but also non-autonomously caused neuroblast loss. We further demonstrated that WDR62 controls brain growth through lineage-specific interactions with master mitotic signaling kinase, AURKA. Depletion of AURKA in neuroblasts drives brain overgrowth, which was suppressed by WDR62 co-depletion. In contrast, glial-specific depletion of AURKA significantly decreased brain volume, which was further decreased by WDR62 co-depletion. Thus, dissecting relative contributions of MCPH factors to individual neural lineages will be critical for understanding complex diseases such as microcephaly. Crown Copyright © 2017. Published by Elsevier Inc. All rights reserved.
In vivo and in vitro hypotensive effect of aqueous extract of Moringa stenopetala.
Mengistu, M; Abebe, Y; Mekonnen, Y; Tolessa, T
2012-12-01
Moringa stenopetala, Baker f. (Moringaceae) is used for food and medicine in Southern Ethiopia. To substantiate the hypotensive effect of M. stenopetala in vivo and in vitro. An in vivo experiment was carried out on male guinea pigs anaesthetized with pentobarbital. The arterial blood pressure was recorded from a carotid artery filled with heparinized saline via an arterial cannula connected to a pressure transducer. For the in vitro experiment the descending thoracic aorta was removed and kept moistened in Krebs-Henseleit solution and then mounted in a 20ml tissue bath maintained at 37°C and bubbled with a mixture of 95% oxygen and 5% carbon dioxide. Crude aqueous leaf extract of M. stenopetala caused significant fall in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial blood pressure (MABP) at doses of 10, 20, 30 and 40 mg/kg in normotensive anaesthetized guinea pigs (n = 12). The effect might have been mediated by non-autonomic nervous system as the effect is not altered by atropine and propranolol. The extract also caused significant dose and time dependent inhibition of K(+) induced contraction on guinea pig aorta. M.stenopetala has blood pressure lowering effect substantiating the use of the plant in traditional medicine.
Impact of seasonal forcing on reactive ecological systems.
Vesipa, Riccardo; Ridolfi, Luca
2017-04-21
Our focus is on the short-term dynamics of reactive ecological systems which are stable in the long term. In these systems, perturbations can exhibit significant transient amplifications before asymptotically decaying. This peculiar behavior has attracted increasing attention. However, reactive systems have so far been investigated assuming that external environmental characteristics remain constant, although environmental conditions (e.g., temperature, moisture, water availability, etc.) can undergo substantial changes due to seasonal cycles. In order to fill this gap, we propose applying the adjoint non-modal analysis to study the impact of seasonal variations of environmental conditions on reactive systems. This tool allows the transient dynamics of a perturbation affecting non-autonomous ecological systems to be described. To show the potential of this approach, a seasonally forced prey-predator model with a Holling II type functional response is studied as an exemplifying case. We demonstrate that seasonalities can greatly affect the transient dynamics of the system. Copyright © 2017 Elsevier Ltd. All rights reserved.
Walsh, Gregory S; Grant, Paul K; Morgan, John A; Moens, Cecilia B
2011-07-01
Components of the planar cell polarity (PCP) pathway are required for the caudal tangential migration of facial branchiomotor (FBM) neurons, but how PCP signaling regulates this migration is not understood. In a forward genetic screen, we identified a new gene, nhsl1b, required for FBM neuron migration. nhsl1b encodes a WAVE-homology domain-containing protein related to human Nance-Horan syndrome (NHS) protein and Drosophila GUK-holder (Gukh), which have been shown to interact with components of the WAVE regulatory complex that controls cytoskeletal dynamics and with the polarity protein Scribble, respectively. Nhsl1b localizes to FBM neuron membrane protrusions and interacts physically and genetically with Scrib to control FBM neuron migration. Using chimeric analysis, we show that FBM neurons have two modes of migration: one involving interactions between the neurons and their planar-polarized environment, and an alternative, collective mode involving interactions between the neurons themselves. We demonstrate that the first mode of migration requires the cell-autonomous functions of Nhsl1b and the PCP components Scrib and Vangl2 in addition to the non-autonomous functions of Scrib and Vangl2, which serve to polarize the epithelial cells in the environment of the migrating neurons. These results define a role for Nhsl1b as a neuronal effector of PCP signaling and indicate that proper FBM neuron migration is directly controlled by PCP signaling between the epithelium and the migrating neurons.
THE RELATIONSHIP BETWEEN TEACHING STYLES AND MOTIVATION TO TEACH AMONG PHYSICAL EDUCATION TEACHERS
Directory of Open Access Journals (Sweden)
Vello Hein
2012-03-01
Full Text Available This study aims to investigate how teachers' motivation to teach is related to different teaching styles. A hundred and seventy six physical education teachers from five European countries participated in the study. Teachers' motivation was measured using an instrument developed by Roth et al., 2007 based on the Self-Determination Theory (Deci and Ryan, 1985 which was tested for suitability for use with physical education teachers. The use of teaching styles was assessed through teachers' self-reported data according to the description of teaching styles presented by Curtner-Smith et al., 2001. The revised confirmatory factor model of the teachers' motivation instrument, with three factors, met the criteria for satisfactory fit indices. The results showed that teachers were more intrinsically motivated to teach than externally. Cross-cultural comparison indicated that the Spanish teachers were more intrinsically motivated whilst Lithuanian teachers were more externally motivated than teachers from the other four countries. Teachers from all five countries reported a more frequent use of reproductive styles than productive styles. The results of the present study confirmed the hypotheses that teachers' autonomous motivation is related to the student-centered or productive teaching styles whilst non-autonomously motivated teachers adopt more teacher-centered or reproductive teaching styles. Intrinsic and introjected motivation was significantly higher among teachers who more frequently employed productive teaching styles than teachers who used them less frequently. Intrinsically motivated teachers using more productive teaching styles can contribute more to the promotion physical activity among students
Fihrer, Irene; McMahon, Cathy
2009-11-01
The current study explored how children's family drawings in the early school years might be related to their exposure to recurrent episodes of maternal depression. We also examined prospectively relations among maternal state of mind regarding attachment derived from the Adult Attachment Interview and earlier mother-child attachment from the Strange Situation Procedure (both measured when the child was 12-15 months old) and later family drawings. Seventy-five mothers were assessed for symptoms of depression periodically between birth and child age 6-8 years. At this age, children completed a family drawing rated using an attachment-based scoring system. Both mothers' state of mind regarding attachment and their overall depression were modestly, but significantly, correlated with a global rating of the child's drawings. When both predictors were considered together, however, neither was significant, reflecting collinearity between the two variables. In this study, women with a non-autonomous state of mind regarding attachment were significantly more likely to experience recurrent depression. The earlier classification of the child's attachment to the mother from the Strange Situation Procedure was not related to the family drawing.
Controlling the optical field chaos in storage ring free-electron lasers
International Nuclear Information System (INIS)
Wang Wenjie
1995-01-01
The controlling of optical field chaos in a storage ring free-electron laser oscillator is discussed by using a phenomenal model. A novel method (which is called the 'beating method') of controlling chaos in a nonlinear dynamical system described by non-autonomous ordinary differential equations was developed. The result of theoretical analysis and numerical simulation shows that the optical field chaos in a storage ring free-electron laser oscillator can be suppressed and a periodic laser intensity can be obtained when a weak periodic control field is added to the optical cavity. The validity of this method of eliminating chaos is confirmed by the fact that the leading Lyapunov characteristic exponent of the system changes from a positive real number to a negative one. A further research is carried out, and it is found that only when the period of the control field equals to an integral multiple of that of the gain modulation in the optical cavity can the optical field chaos be suppressed. This means that the 'beating method' of controlling chaos is a kind of resonant method. A way to determine the 'best beating position' in the phase trajectory has also been obtained
Discrete Painlevé equations from Y-systems
International Nuclear Information System (INIS)
Hone, Andrew N W; Inoue, Rei
2014-01-01
We consider T-systems and Y-systems arising from cluster mutations applied to quivers that have the property of being periodic under a sequence of mutations. The corresponding nonlinear recurrences for cluster variables (coefficient-free T-systems) were described in the work of Fordy and Marsh, who completely classified all such quivers in the case of period 1, and characterized them in terms of the skew-symmetric exchange matrix B that defines the quiver. A broader notion of periodicity in general cluster algebras was introduced by Nakanishi, who also described the corresponding Y-systems, and T-systems with coefficients. A result of Fomin and Zelevinsky says that the coefficient-free T-system provides a solution of the Y-system. In this paper, we show that in general there is a discrepancy between these two systems, in the sense that the solution of the former does not correspond to the general solution of the latter. This discrepancy is removed by introducing additional non-autonomous coefficients into the T-system. In particular, we focus on the period 1 case and show that, when the exchange matrix B is degenerate, discrete Painlevé equations can arise from this construction. This article is part of a special issue of Journal of Physics A: Mathematical and Theoretical devoted to ‘Cluster algebras in mathematical physics’. (paper)
Optimal Control of Engine Warmup in Hybrid Vehicles
Directory of Open Access Journals (Sweden)
van Reeven Vital
2016-01-01
Full Text Available An Internal Combustion Engine (ICE under cold conditions experiences increased friction losses due to a high viscosity of the lubricant. With the additional control freedom present in hybrid electric vehicles, the losses during warmup can be minimized and fuel can be saved. In this paper, firstly, a control-oriented model of the ICE, describing the warmup behavior, is developed and validated on measured vehicle data. Secondly, the two-state, non-autonomous fuel optimization, for a parallel hybrid electric vehicle with stop-start functionality, is solved using optimal control theory. The principal behavior of the Lagrange multipliers is explicitly derived, including the discontinuities (jumps that are caused by the constraints on the lubricant temperature and the energy in the battery system. The minimization of the Hamiltonian for this two-state problem is also explicitly solved, resulting in a computationally efficient algorithm. The optimal controller shows the fuel benefit, as a function of the initial temperature, for a long-haul truck simulated on the FTP-75.
Vrangalova, Zhana
2015-05-01
Engagement in casual sex (or hooking up) is generally feared to have negative well-being consequences; however, empirical evidence is inconclusive, pointing toward potential moderators. Using self-determination theory (SDT), we hypothesized that well-being following hookups would depend on the type and level of motivation for hooking up. A university-wide sample of 528 undergraduates completed online surveys at the beginning (T1) and end (T3) of one academic year. After controlling for demographics, personality traits (i.e., neuroticism and extraversion), prior casual and romantic sex, and T1 well-being, having genital hookups between T1 and T3 for non-autonomous reasons (i.e., due to self-imposed pressures, external contingencies and controls, or complete lack of intentionality) was linked to lower self-esteem, higher depression and anxiety, and more physical symptoms. Autonomous hookup motivation (i.e., emanating from one's self) was not linked to any outcomes. Compared to peers without hookups, those with high non-autonomy in their hookups typically had inferior well-being; this was not true of those with low non-autonomy hookups. Gender differences, implications for SDT and casual sex research, and implications for educational programs and clinical work are discussed.
Interactions between the amnioserosa and the epidermis revealed by the function of the u-shaped gene
Directory of Open Access Journals (Sweden)
Karolina Lada
2012-02-01
Dorsal closure (DC is an essential step during Drosophila development whereby a hole is sealed in the dorsal epidermis and serves as a model for cell sheet morphogenesis and wound healing. It involves the orchestrated interplay of transcriptional networks and dynamic regulation of cell machinery to bring about shape changes, mechanical forces, and emergent properties. Here we provide insight into the regulation of dorsal closure by describing novel autonomous and non-autonomous roles for U-shaped (Ush in the amnioserosa, the epidermis, and in mediation of communication between the tissues. We identified Ush by gene expression microarray analysis of Dpp signaling targets and show that Ush mediates some DC functions of Dpp. By selectively restoring Ush function in either the AS or the epidermis in ush mutants, we show that the AS makes a greater (Ush-dependent contribution to closure than the epidermis. A signal from the AS induces epidermal cell elongation and JNK activation in the DME, while cable formation requires Ush on both sides of the leading edge, i.e. in both the AS and epidermis. Our study demonstrates that the amnioserosa and epidermis communicate at several steps during the process: sometimes the epidermis instructs the amnioserosa, other times the AS instructs the epidermis, and still other times they appear to collaborate.
Modelling the interaction between flooding events and economic growth
Directory of Open Access Journals (Sweden)
J. Grames
2015-06-01
Full Text Available Socio-hydrology describes the interaction between the socio-economy and water. Recent models analyze the interplay of community risk-coping culture, flooding damage and economic growth (Di Baldassarre et al., 2013; Viglione et al., 2014. These models descriptively explain the feedbacks between socio-economic development and natural disasters like floods. Contrary to these descriptive models, our approach develops an optimization model, where the intertemporal decision of an economic agent interacts with the hydrological system. In order to build this first economic growth model describing the interaction between the consumption and investment decisions of an economic agent and the occurrence of flooding events, we transform an existing descriptive stochastic model into an optimal deterministic model. The intermediate step is to formulate and simulate a descriptive deterministic model. We develop a periodic water function to approximate the former discrete stochastic time series of rainfall events. Due to the non-autonomous exogenous periodic rainfall function the long-term path of consumption and investment will be periodic.
The biophysical stage of radiation carcinogenesis
International Nuclear Information System (INIS)
Rossi, H.H.; Zaider, M.
1986-01-01
The dependence of the induction of cancer on the absorbed dose of ionizing radiations has been specified in terms of increasing complexity. The first notion of the linear hypothesis is now frequently replaced with a dependence on both the first and second powers of the dose the linear-quadratic model, which implies proportionality at low doses only. Microdosimetric considerations and in particular the theory of dual radiation action would be in accord with this relation if tumors were to arise from single cells as the result of a transformation that depends only on the radiation received by the cell. In this case it must be expected that the linear portion of the dose-effect curve is dose rate independent but that the quadratic component may decrease with decreasing dose rate because of repair. However it was shown some time ago that the dose-incidence relation of a neoplasm indicates a non-autonomous response because of departure from a linear dependence when the mean number of events in cells is much less than one in neutron irradiations. Another discrepancy is the repeated observation that reduction of dose rate, while resulting in the expected lessening of the effectiveness of low-LET radiation, increases the effectiveness of neutrons especially in the case of oncogenic cell transformation. 32 refs., 3 figs
Weak nonlinear analysis of magneto–convection under magnetic field modulation
International Nuclear Information System (INIS)
Bhadauria, B S; Kiran, Palle
2014-01-01
An analytic study of heat transport in an electrically conducting fluid layer is performed under a non-uniform time-dependent magnetic field. The applied vertical magnetic field consists of two parts: a constant part and a time-dependent periodic part, which varies sinusoidally with time. A weakly nonlinear theory has been considered to investigate heat transfer in the fluid layer. The heat transfer coefficient is obtained by deriving the non-autonomous Ginzburg–Landau equation for an amplitude of convection. This amplitude of convection is derived by using NDSolve Mathematica 8, and the results are verified using Runge–Kutta–Fehlberg method. The Nusselt number is obtained in terms of various system parameters and the effect of each parameter on heat transport is reported in detail. The effect of magnetic Prandtl number Pm, amplitude of modulation δ is to enhance the heat transfer. The Chandrasekhar number Q, modulation frequency ω is to stabilize the system. Further, it is found that magnetic modulation can be used effectively in either enhancing the heat transfer or diminishing it. (paper)
Guo, Jiwei; Jin, Dan
2015-05-01
The sex comb on midleg (scm) gene encodes a transcriptional repressor and belongs to the Polycomb group (PcG) of genes, which regulates growth in Drosophila. Scm interacts with Polyhomeotic (a PcG protein) in vitro by recognizing its SPM domain. The homologous human protein, Sex comb on midleg-like 2 (Scml2), has been implicated in malignant brain tumors. Will die slowly (Wds) is another factor that regulates Drosophila development, and its homologous human protein, WD repeat domain 5(Wdr5), is part of the mixed lineage leukemia 1(MLL1) complex that promotes histone H3Lys4 methylation. Like Scml2, Wdr5 has been implicated in certain cancers; this protein plays an important role in leukemogenesis. In this study, we find that loss-of-function mutations in Scm result in non-autonomous tissue overgrowth in Drosophila, and determine that Scm is essential for ommatidium development and important for cell survival in Drosophila. Furthermore, our research suggests a relationship between Wds and Scm; Wds promotes Scm degradation through ubiquitination in vitro in Drosophila. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
Balaji, Nidish Narayanaa; Krishna, I. R. Praveen; Padmanabhan, C.
2018-05-01
The Harmonic Balance Method (HBM) is a frequency-domain based approximation approach used for obtaining the steady state periodic behavior of forced dynamical systems. Intrinsically these systems are non-autonomous and the method offers many computational advantages over time-domain methods when the fundamental period of oscillation is known (generally fixed as the forcing period itself or a corresponding sub-harmonic if such behavior is expected). In the current study, a modified approach, based on He's Energy Balance Method (EBM), is applied to obtain the periodic solutions of conservative systems. It is shown that by this approach, periodic solutions of conservative systems on iso-energy manifolds in the phase space can be obtained very efficiently. The energy level provides the additional constraint on the HBM formulation, which enables the determination of the period of the solutions. The method is applied to the linear harmonic oscillator, a couple of nonlinear oscillators, the elastic pendulum and the Henon-Heiles system. The approach is used to trace the bifurcations of the periodic solutions of the last two, being 2 degree-of-freedom systems demonstrating very rich dynamical behavior. In the process, the advantages offered by the current formulation of the energy balance is brought out. A harmonic perturbation approach is used to evaluate the stability of the solutions for the bifurcation diagram.
The Proprioceptive System Regulates Morphologic Restoration of Fractured Bones
Directory of Open Access Journals (Sweden)
Ronen Blecher
2017-08-01
Full Text Available Successful fracture repair requires restoration of bone morphology and mechanical integrity. Recent evidence shows that fractured bones of neonatal mice undergo spontaneous realignment, dubbed “natural reduction.” Here, we show that natural reduction is regulated by the proprioceptive system and improves with age. Comparison among mice of different ages revealed, surprisingly, that 3-month-old mice exhibited more rapid and effective natural reduction than newborns. Fractured bones of null mutants for transcription factor Runx3, lacking functional proprioceptors, failed to realign properly. Blocking Runx3 expression in the peripheral nervous system, but not in limb mesenchyme, recapitulated the null phenotype, as did inactivation of muscles flanking the fracture site. Egr3 knockout mice, which lack muscle spindles but not Golgi tendon organs, displayed a less severe phenotype, suggesting that both receptor types, as well as muscle contraction, are required for this regulatory mechanism. These findings uncover a physiological role for proprioception in non-autonomous regulation of skeletal integrity.
Addiction and autonomy: can addicted people consent to the prescription of their drug of addiction?
Foddy, Bennett; Savulescu, Julian
2006-02-01
It is often claimed that the autonomy of heroin addicts is compromised when they are choosing between taking their drug of addiction and abstaining. This is the basis of claims that they are incompetent to give consent to be prescribed heroin. We reject these claims on a number of empirical and theoretical grounds. First we argue that addicts are likely to be sober, and thus capable of rational thought, when approaching researchers to participate in research. We reject behavioural evidence purported to establish that addicts lack autonomy. We present an argument that extrinsic forces must be irresistible in order to make a choice non-autonomous. We argue that heroin does not present such an irresistible force. We make a case that drug-oriented desires are strong regular appetitive desires, which do not compromise consent. Finally we argue that an addict's apparent desire to engage in a harmful act cannot be construed as evidence of irrational or compulsive thought. On these arguments, a sober heroin addict must be considered competent, autonomous and capable of giving consent. More generally, any argument against legalisation of drugs or supporting infringement of the liberty of those desiring to take drugs of addiction must be based on considerations of harm and paternalism, and not on false claims that addicts lack freedom of the will.
Coercive treatment and autonomy in psychiatry.
Sjöstrand, Manne; Helgesson, Gert
2008-02-01
There are three lines of argument in defence of coercive treatment of patients with mental disorders: arguments regarding (1) societal interests to protect others, (2) the patients' own health interests, and (3) patient autonomy. In this paper, we analyse these arguments in relation to an idealized case, where a person with a mental disorder claims not to want medical treatment for religious reasons. We also discuss who should decide what in situations where patients with mental disorders deny treatment on seemingly rational grounds. We conclude that, in principle, coercive treatment cannot be defended for the sake of protecting others. While coercive actions can be acceptable in order to protect close family and others, medical treatment is not justified for such reasons but should be given only in the interest of patients. Coercive treatment may be required in order to promote the patient's health interests, but health interests have to waive if they go against the autonomous interests of the patient. We argue that non-autonomous patients can have reasons, rooted in their deeply-set values, to renounce compulsory institutional treatment, and that such reasons should be respected unless it can be assumed that their new predicaments have caused them to change their views.
Mathematical modelling of decline in follicle pool during female reproductive ageing.
Thilagam, Alagu
2016-03-01
The factors which govern the subtle links between follicle loss and mammalian female reproductive ageing remain unclear despite extensive studies undertaken to understand the critical physiological and biochemical mechanisms that underly the accelerated decline in follicle numbers in women older than 37 years. It is not certain whether there is a sole control by the ovary or whether other factors which affect ageing also intersect with the ovarian effect. There is convincing experimental evidence for an interplay of several processes that seem to influence the follicle loss-female reproductive ageing links, with specific hormones (follicle-stimulating hormone, anti-Müllerian hormone, dehydroepiandrosterone) noted to play important roles in follicular dynamics and ovarian ageing. In this work, we examine the subtle links between the rate of follicular decline with ageing and the role of hormones via a series of non-autonomous equations. Simulation results based on the time evolution of the number of ovarian follicles and biochemical changes in the ovarian environment influenced by hormone levels is compared with empirical data based on follicle loss-reproductive ageing correlation studies. © Crown copyright 2015.
Branched-chain amino acid catabolism is a conserved regulator of physiological ageing.
Mansfeld, Johannes; Urban, Nadine; Priebe, Steffen; Groth, Marco; Frahm, Christiane; Hartmann, Nils; Gebauer, Juliane; Ravichandran, Meenakshi; Dommaschk, Anne; Schmeisser, Sebastian; Kuhlow, Doreen; Monajembashi, Shamci; Bremer-Streck, Sibylle; Hemmerich, Peter; Kiehntopf, Michael; Zamboni, Nicola; Englert, Christoph; Guthke, Reinhard; Kaleta, Christoph; Platzer, Matthias; Sühnel, Jürgen; Witte, Otto W; Zarse, Kim; Ristow, Michael
2015-12-01
Ageing has been defined as a global decline in physiological function depending on both environmental and genetic factors. Here we identify gene transcripts that are similarly regulated during physiological ageing in nematodes, zebrafish and mice. We observe the strongest extension of lifespan when impairing expression of the branched-chain amino acid transferase-1 (bcat-1) gene in C. elegans, which leads to excessive levels of branched-chain amino acids (BCAAs). We further show that BCAAs reduce a LET-363/mTOR-dependent neuro-endocrine signal, which we identify as DAF-7/TGFβ, and that impacts lifespan depending on its related receptors, DAF-1 and DAF-4, as well as ultimately on DAF-16/FoxO and HSF-1 in a cell-non-autonomous manner. The transcription factor HLH-15 controls and epistatically synergizes with BCAT-1 to modulate physiological ageing. Lastly and consistent with previous findings in rodents, nutritional supplementation of BCAAs extends nematodal lifespan. Taken together, BCAAs act as periphery-derived metabokines that induce a central neuro-endocrine response, culminating in extended healthspan.
Institute of Scientific and Technical Information of China (English)
Qingshu Meng; Kaifu Chen; Lina Ma; Songnian Hu; Jun Yu
2011-01-01
Transposons are sequence elements widely distributed among genomes of all three kingdoms of life, providing genomic changes and playing significant roles in genome evolution. Trichomonas vaginalis is an excellent model system for transposon study since its genome ( ～ 160 Mb) has been sequenced and is composed of ～65% transposons and other repetitive elements. In this study, we primarily report the identification of Kolobok-type transposons (termed tvBac) in T. vaginalis and the results of transposase sequence analysis. We categorized 24 novel subfamilies of the Kolobok element, including one autonomous subfamily and 23 non-autonomous subfamilies. We also identified a novel H2CH motif in tvBac transposases based on multiple sequence alignment. In addition, we supposed that tvBac and Mutator transposons may have evolved independently from a common ancestor according to our phylogenetic analysis. Our results provide basic information for the understanding of the function and evolution of tvBac transposons in particular and other related transposon families in general.
Convergence in gradient systems with branching of equilibria
International Nuclear Information System (INIS)
Galaktionov, V A; Pohozaev, Stanislav I; Shishkov, A E
2007-01-01
The basic model is a semilinear elliptic equation with coercive C 1 non-linearity: Δψ+f(ψ)=0 in Ω, ψ=0 on ∂Ω, where Ω subset of R N is a bounded smooth domain. The main hypothesis (H R ) about resonance branching is as follows: if a branching of equilibria occurs at a point ψ with k-dimensional kernel of the linearized operator Δ+f'(ψ)I, then the branching subset S k at ψ is a locally smooth k-dimensional manifold. For N=1 the first result on the stabilization to a single equilibrium is due to Zelenyak (1968). It is shown that Zelenyak's approach, which is based on the analysis of Lyapunov functions, can be extended to general gradient systems in Hilbert spaces with smooth resonance branching. The case of asymptotically small non-autonomous perturbations of such systems is also considered. The approach developed here represents an alternative to Hale's stabilization method (1992) and other similar techniques in the theory of gradient systems. Bibliography: 32 titles.
The LINEs and SINEs of Entamoeba histolytica: comparative analysis and genomic distribution.
Bakre, Abhijeet A; Rawal, Kamal; Ramaswamy, Ram; Bhattacharya, Alok; Bhattacharya, Sudha
2005-07-01
Autonomous non-long terminal repeat retrotransposons are commonly referred to as long interspersed elements (LINEs). Short non-autonomous elements that borrow the LINE machinery are called SINES. The Entamoeba histolytica genome contains three classes of LINEs and SINEs. Together the EhLINEs/SINEs account for about 6% of the genome. The recognizable functional domains in all three EhLINEs included reverse transcriptase and endonuclease. A novel feature was the presence of two types of members-some with a single long ORF (less frequent) and some with two ORFs (more frequent) in both EhLINE1 and 2. The two ORFs were generated by conserved changes leading to stop codon. Computational analysis of the immediate flanking sequences for each element showed that they inserted in AT-rich sequences, with a preponderance of Ts in the upstream site. The elements were very frequently located close to protein-coding genes and other EhLINEs/SINEs. The possible influence of these elements on expression of neighboring genes needs to be determined.
[Non-LTR retrotransposons: LINEs and SINEs in plant genome].
Cheng, Xu-Dong; Ling, Hong-Qing
2006-06-01
Retrotransposons are one of the drivers of genome evolution. They include LTR (long terminal repeat) retrotransposons, which widespread in Eukaryotagenomes, show structural similarity to retroviruses. Non-LTR retrotransposons were first discovered in animal genomes and then identified as ubiquitous components of nuclear genomes in many species across the plant kingdom. They constitute a large fraction of the repetitive DNA. Non-LTR retrotransposons are divided into LINEs (long interspersed nuclear elements) and SINEs (short interspersed nuclear elements). Transposition of non-LTR retrotransposons is rarely observed in plants indicating that most of them are inactive and/or under regulation of the host genome. Transposition is poorly understood, but experimental evidence from other genetic systems shows that LINEs are able to transpose autonomously while non-autonomous SINEs depend on the reverse transcription machinery of other retrotransposons. Phylogenic analysis shows LINEs are probably the most ancient class of retrotransposons in plant genomes, while the origin of SINEs is unknown. This review sums up the above data and wants to show readers a clear picture of non-LTR retrotransposons.
RUDI, a short interspersed element of the V-SINE superfamily widespread in molluscan genomes.
Luchetti, Andrea; Šatović, Eva; Mantovani, Barbara; Plohl, Miroslav
2016-06-01
Short interspersed elements (SINEs) are non-autonomous retrotransposons that are widespread in eukaryotic genomes. They exhibit a chimeric sequence structure consisting of a small RNA-related head, an anonymous body and an AT-rich tail. Although their turnover and de novo emergence is rapid, some SINE elements found in distantly related species retain similarity in certain core segments (or highly conserved domains, HCD). We have characterized a new SINE element named RUDI in the bivalve molluscs Ruditapes decussatus and R. philippinarum and found this element to be widely distributed in the genomes of a number of mollusc species. An unexpected structural feature of RUDI is the HCD domain type V, which was first found in non-amniote vertebrate SINEs and in the SINE from one cnidarian species. In addition to the V domain, the overall sequence conservation pattern of RUDI elements resembles that found in ancient AmnSINE (~310 Myr old) and Au SINE (~320 Myr old) families, suggesting that RUDI might be among the most ancient SINE families. Sequence conservation suggests a monophyletic origin of RUDI. Nucleotide variability and phylogenetic analyses suggest long-term vertical inheritance combined with at least one horizontal transfer event as the most parsimonious explanation for the observed taxonomic distribution.
Schwichtenberg, Katrin; Wenke, Torsten; Zakrzewski, Falk; Seibt, Kathrin M; Minoche, André; Dohm, Juliane C; Weisshaar, Bernd; Himmelbauer, Heinz; Schmidt, Thomas
2016-01-01
Short interspersed nuclear elements (SINEs) are non-autonomous non-long terminal repeat retrotransposons which are widely distributed in eukaryotic organisms. While SINEs have been intensively studied in animals, only limited information is available about plant SINEs. We analysed 22 SINE families from seven genomes of the Amaranthaceae family and identified 34 806 SINEs, including 19 549 full-length copies. With the focus on sugar beet (Beta vulgaris), we performed a comparative analysis of the diversity, genomic and chromosomal organization and the methylation of SINEs to provide a detailed insight into the evolution and age of Amaranthaceae SINEs. The lengths of consensus sequences of SINEs range from 113 nucleotides (nt) up to 224 nt. The SINEs show dispersed distribution on all chromosomes but were found with higher incidence in subterminal euchromatic chromosome regions. The methylation of SINEs is increased compared with their flanking regions, and the strongest effect is visible for cytosines in the CHH context, indicating an involvement of asymmetric methylation in the silencing of SINEs. © 2015 The Authors The Plant Journal © 2015 John Wiley & Sons Ltd.
SINEs as driving forces in genome evolution.
Schmitz, J
2012-01-01
SINEs are short interspersed elements derived from cellular RNAs that repetitively retropose via RNA intermediates and integrate more or less randomly back into the genome. SINEs propagate almost entirely vertically within their host cells and, once established in the germline, are passed on from generation to generation. As non-autonomous elements, their reverse transcription (from RNA to cDNA) and genomic integration depends on the activity of the enzymatic machinery of autonomous retrotransposons, such as long interspersed elements (LINEs). SINEs are widely distributed in eukaryotes, but are especially effectively propagated in mammalian species. For example, more than a million Alu-SINE copies populate the human genome (approximately 13% of genomic space), and few master copies of them are still active. In the organisms where they occur, SINEs are a challenge to genomic integrity, but in the long term also can serve as beneficial building blocks for evolution, contributing to phenotypic heterogeneity and modifying gene regulatory networks. They substantially expand the genomic space and introduce structural variation to the genome. SINEs have the potential to mutate genes, to alter gene expression, and to generate new parts of genes. A balanced distribution and controlled activity of such properties is crucial to maintaining the organism's dynamic and thriving evolution. Copyright © 2012 S. Karger AG, Basel.
LINEs, SINEs and other retroelements: do birds of a feather flock together?
Roy-Engel, Astrid M
2012-01-01
Mobile elements account for almost half of the mass of the human genome. Only the retroelements from the non-LTR (long terminal repeat) retrotransposon family, which include the LINE-1 (L1) and its non-autonomous partners, are currently active and contributing to new insertions. Although these elements seem to share the same basic amplification mechanism, the activity and success of the different types of retroelements varies. For example, Alu-induced mutagenesis is responsible for the majority of the documented instances of human disease induced by insertion of retroelements. Using copy number in mammals as an indicator, some SINEs have been vastly more successful than other retroelements, such as the retropseudogenes and even L1, likely due to differences in post-insertion selection and ability to overcome cellular controls. SINE and LINE integration can be differentially influenced by cellular factors, indicating some differences between in their amplification mechanisms. We focus on the known aspects of this group of retroelements and highlight their similarities and differences that may significantly influence their biological impact.
RNA-Mediated Gene Duplication and Retroposons: Retrogenes, LINEs, SINEs, and Sequence Specificity
2013-01-01
A substantial number of “retrogenes” that are derived from the mRNA of various intron-containing genes have been reported. A class of mammalian retroposons, long interspersed element-1 (LINE1, L1), has been shown to be involved in the reverse transcription of retrogenes (or processed pseudogenes) and non-autonomous short interspersed elements (SINEs). The 3′-end sequences of various SINEs originated from a corresponding LINE. As the 3′-untranslated regions of several LINEs are essential for retroposition, these LINEs presumably require “stringent” recognition of the 3′-end sequence of the RNA template. However, the 3′-ends of mammalian L1s do not exhibit any similarity to SINEs, except for the presence of 3′-poly(A) repeats. Since the 3′-poly(A) repeats of L1 and Alu SINE are critical for their retroposition, L1 probably recognizes the poly(A) repeats, thereby mobilizing not only Alu SINE but also cytosolic mRNA. Many flowering plants only harbor L1-clade LINEs and a significant number of SINEs with poly(A) repeats, but no homology to the LINEs. Moreover, processed pseudogenes have also been found in flowering plants. I propose that the ancestral L1-clade LINE in the common ancestor of green plants may have recognized a specific RNA template, with stringent recognition then becoming relaxed during the course of plant evolution. PMID:23984183
Addison, Megan; Xu, Qiling; Cayuso, Jordi; Wilkinson, David G
2018-06-04
The patterning of tissues to form subdivisions with distinct and homogeneous regional identity is potentially disrupted by cell intermingling. Transplantation studies suggest that homogeneous segmental identity in the hindbrain is maintained by identity switching of cells that intermingle into another segment. We show that switching occurs during normal development and is mediated by feedback between segment identity and the retinoic acid degrading enzymes, cyp26b1 and cyp26c1. egr2, which specifies the segmental identity of rhombomeres r3 and r5, underlies the lower expression level of cyp26b1 and cyp26c1 in r3 and r5 compared with r2, r4, and r6. Consequently, r3 or r5 cells that intermingle into adjacent segments encounter cells with higher cyp26b1/c1 expression, which we find is required for downregulation of egr2b expression. Furthermore, egr2b expression is regulated in r2, r4, and r6 by non-autonomous mechanisms that depend upon the number of neighbors that express egr2b. These findings reveal that a community regulation of retinoid signaling maintains homogeneous segmental identity. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.
Diffusion properties of a guiding center plasma in a model electrostatic turbulence
International Nuclear Information System (INIS)
Pettini, M.; Vulpiani, A.; Misguich, J.H.; Balescu, R.; De Leener, M.; Orban, J.
1986-01-01
Numerical simulations have been performed to calculate the diffusion coefficient of several hundreds of charged particles across a strong magnetic field B, due to a known spectrum of electrostatic fluctuations. The results have been compared with the turbulent diffusion theory proposed by Misguich et al. The equation of motion is solved with a model electrostatic potential. This potential is also the Hamiltonian of this chaotic non-autonomous system: positive Lyapunov exponents are found in qualitative agreement with theoretical predictions. The absolute diffusion coefficients found in two different models exhibit a transition between two scaling regions: a classical scaling at low amplitudes (D ∼ E 2 /B 2 ), and a Bohm scaling at higher amplitudes (D ∼ E/B), in agreement with the predictions for these models. The value of the diffusion coefficient obtained in the isotropic model shows a satisfactory agreement with the theory. The study of the relative diffusion of initially close particles yields a clear quantitative confirmation of the clump effect and of the validity of the theoretical treatment of such nonlinearities. (26 fig, 20 refs)
Spreading of a prion domain from cell-to-cell by vesicular transport in Caenorhabditis elegans.
Directory of Open Access Journals (Sweden)
Carmen I Nussbaum-Krammer
2013-03-01
Full Text Available Prion proteins can adopt self-propagating alternative conformations that account for the infectious nature of transmissible spongiform encephalopathies (TSEs and the epigenetic inheritance of certain traits in yeast. Recent evidence suggests a similar propagation of misfolded proteins in the spreading of pathology of neurodegenerative diseases including Alzheimer's or Parkinson's disease. Currently there is only a limited number of animal model systems available to study the mechanisms that underlie the cell-to-cell transmission of aggregation-prone proteins. Here, we have established a new metazoan model in Caenorhabditis elegans expressing the prion domain NM of the cytosolic yeast prion protein Sup35, in which aggregation and toxicity are dependent upon the length of oligopeptide repeats in the glutamine/asparagine (Q/N-rich N-terminus. NM forms multiple classes of highly toxic aggregate species and co-localizes to autophagy-related vesicles that transport the prion domain from the site of expression to adjacent tissues. This is associated with a profound cell autonomous and cell non-autonomous disruption of mitochondrial integrity, embryonic and larval arrest, developmental delay, widespread tissue defects, and loss of organismal proteostasis. Our results reveal that the Sup35 prion domain exhibits prion-like properties when expressed in the multicellular organism C. elegans and adapts to different requirements for propagation that involve the autophagy-lysosome pathway to transmit cytosolic aggregation-prone proteins between tissues.
Cong, Zhang
2018-03-01
Based on extended state observer, a novel and practical design method is developed to solve the distributed cooperative tracking problem of higher-order nonlinear multiagent systems with lumped disturbance in a fixed communication topology directed graph. The proposed method is designed to guarantee all the follower nodes ultimately and uniformly converge to the leader node with bounded residual errors. The leader node, modeled as a higher-order non-autonomous nonlinear system, acts as a command generator giving commands only to a small portion of the networked follower nodes. Extended state observer is used to estimate the local states and lumped disturbance of each follower node. Moreover, each distributed controller can work independently only requiring the relative states and/or the estimated relative states information between itself and its neighbors. Finally an engineering application of multi flight simulators systems is demonstrated to test and verify the effectiveness of the proposed algorithm. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.
Hoffmann, Christine; Ziegler, Ute; Buschmann, Anne; Weber, Artur; Kupfer, Leila; Oelschlegel, Anja; Hammerschmidt, Baerbel; Groschup, Martin H
2007-03-01
To elucidate the still-unknown pathogenesis of bovine spongiform encephalopathy (BSE), an oral BSE challenge and sequential kill study was carried out on 56 calves. Relevant tissues belonging to the peripheral and central nervous system, as well as to the lymphoreticular tract, from necropsied animals were analysed by highly sensitive immunohistochemistry and immunoblotting techniques to reveal the presence of BSE-associated pathological prion protein (PrPSc) depositions. Our results demonstrate two routes involving the autonomic nervous system through which BSE prions spread by anterograde pathways from the gastrointestinal tract (GIT) to the central nervous system (CNS): (i) via the coeliac and mesenteric ganglion complex, splanchnic nerves and the lumbal/caudal thoracic spinal cord (representing the sympathetic GIT innervation); and (ii) via the Nervus vagus (parasympathetic GIT innervation). The dorsal root ganglia seem to be subsequently affected, so it is likely that BSE prion invasion of the non-autonomic peripheral nervous system (e.g. sciatic nerve) is a secondary retrograde event following prion replication in the CNS. Moreover, BSE-associated PrPSc was already detected in the brainstem of an animal 24 months post-infection, which is 8 months earlier than reported previously. These findings are important for the understanding of BSE pathogenesis and for the development of new diagnostic strategies for this infectious disease.
Thermodynamics of a periodically driven qubit
Donvil, Brecht
2018-04-01
We present a new approach to the open system dynamics of a periodically driven qubit in contact with a temperature bath. We are specifically interested in the thermodynamics of the qubit. It is well known that by combining the Markovian approximation with Floquet theory it is possible to derive a stochastic Schrödinger equation in for the state of the qubit. We follow here a different approach. We use Floquet theory to embed the time-non autonomous qubit dynamics into time-autonomous yet infinite dimensional dynamics. We refer to the resulting infinite dimensional system as the dressed-qubit. Using the Markovian approximation we derive the stochastic Schrödinger equation for the dressed-qubit. The advantage of our approach is that the jump operators are ladder operators of the Hamiltonian. This simplifies the formulation of the thermodynamics. We use the thermodynamics of the infinite dimensional system to recover the thermodynamical description for the driven qubit. We compare our results with the existing literature and recover the known results.
Mitochondria-Associated Membranes As Networking Platforms and Regulators of Cancer Cell Fate
Directory of Open Access Journals (Sweden)
Maria Livia Sassano
2017-08-01
Full Text Available The tight cross talk between two essential organelles of the cell, the endoplasmic reticulum (ER and mitochondria, is spatially and functionally regulated by specific microdomains known as the mitochondria-associated membranes (MAMs. MAMs are hot spots of Ca2+ transfer between the ER and mitochondria, and emerging data indicate their vital role in the regulation of fundamental physiological processes, chief among them mitochondria bioenergetics, proteostasis, cell death, and autophagy. Moreover, and perhaps not surprisingly, it has become clear that signaling events regulated at the ER–mitochondria intersection regulate key processes in oncogenesis and in the response of cancer cells to therapeutics. ER–mitochondria appositions have been shown to dynamically recruit oncogenes and tumor suppressors, modulating their activity and protein complex formation, adapt the bioenergetic demand of cancer cells and to regulate cell death pathways and redox signaling in cancer cells. In this review, we discuss some emerging players of the ER–mitochondria contact sites in mammalian cells, the key processes they regulate and recent evidence highlighting the role of MAMs in shaping cell-autonomous and non-autonomous signals that regulate cancer growth.
Schimizzi, Gregory V; Maher, Meghan T; Loza, Andrew J; Longmore, Gregory D
2016-01-01
The establishment and maintenance of apical-basal polarity is a defining characteristic and essential feature of functioning epithelia. Apical-basal polarity (ABP) proteins are also tumor suppressors that are targeted for disruption by oncogenic viruses and are commonly mutated in human carcinomas. Disruption of these ABP proteins is an early event in cancer development that results in increased proliferation and epithelial disorganization through means not fully characterized. Using the proliferating Drosophila melanogaster wing disc epithelium, we demonstrate that disruption of the junctional vs. basal polarity complexes results in increased epithelial proliferation via distinct downstream signaling pathways. Disruption of the basal polarity complex results in JNK-dependent proliferation, while disruption of the junctional complex primarily results in p38-dependent proliferation. Surprisingly, the Rho-Rok-Myosin contractility apparatus appears to play opposite roles in the regulation of the proliferative phenotype based on which polarity complex is disrupted. In contrast, non-autonomous Tumor Necrosis Factor (TNF) signaling appears to suppress the proliferation that results from apical-basal polarity disruption, regardless of which complex is disrupted. Finally we demonstrate that disruption of the junctional polarity complex activates JNK via the Rho-Rok-Myosin contractility apparatus independent of the cortical actin regulator, Moesin.
Nonlinear Dynamic Theory of Acute Cell Injuries and Brain Ischemia
Taha, Doaa; Anggraini, Fika; Degracia, Donald; Huang, Zhi-Feng
2015-03-01
Cerebral ischemia in the form of stroke and cardiac arrest brain damage affect over 1 million people per year in the USA alone. In spite of close to 200 clinical trials and decades of research, there are no treatments to stop post-ischemic neuron death. We have argued that a major weakness of current brain ischemia research is lack of a deductive theoretical framework of acute cell injury to guide empirical studies. A previously published autonomous model based on the concept of nonlinear dynamic network was shown to capture important facets of cell injury, linking the concept of therapeutic to bistable dynamics. Here we present an improved, non-autonomous formulation of the nonlinear dynamic model of cell injury that allows multiple acute injuries over time, thereby allowing simulations of both therapeutic treatment and preconditioning. Our results are connected to the experimental data of gene expression and proteomics of neuron cells. Importantly, this new model may be construed as a novel approach to pharmacodynamics of acute cell injury. The model makes explicit that any pro-survival therapy is always a form of sub-lethal injury. This insight is expected to widely influence treatment of acute injury conditions that have defied successful treatment to date. This work is supported by NIH NINDS (NS081347) and Wayne State University President's Research Enhancement Award.
Chaotic Transport in Circumterrestrial Orbits
Rosengren, Aaron Jay
2018-04-01
The slow deformation of circumterrestrial orbits in the medium region, subject to lunisolar secular resonances, is well approximated by a Hamiltonian system with 2.5 degrees of freedom. This dynamical model is referred to in the astrophysical and celestial dynamics communities as the quadrupolar, secular, hierarchical three-body problem, and, in the non-autonomous case, gives rise to the classical Kozai-Lidov mechanism. In the time-dependent model, brought about in our case by the Moon's perturbed motion, the action variables of the system may experience chaotic variations and large drifts due to the possible overlap of nearby resonances. Using variational chaos indicators, we compute high-resolution portraits of the action space, revealing the existence of tori and structures filling chaotic regions. Our refined and elaborate calculations allow us to isolate precise initial conditions near specific areas of interest and to study their asymptotic behavior in time. We highlight in particular how the drift in phase space is mediated by the complement of the numerically detected KAM tori. Despite their reputed normality, Earth satellite orbits can possess an extraordinarily rich spectrum of dynamical behaviors, and, like the small body remnants of Solar system formation, they have all the complications that make them very interesting candidates for testing the modern tools of chaos theory.
Seibt, Kathrin M; Wenke, Torsten; Muders, Katja; Truberg, Bernd; Schmidt, Thomas
2016-05-01
Short interspersed nuclear elements (SINEs) are highly abundant non-autonomous retrotransposons that are widespread in plants. They are short in size, non-coding, show high sequence diversity, and are therefore mostly not or not correctly annotated in plant genome sequences. Hence, comparative studies on genomic SINE populations are rare. To explore the structural organization and impact of SINEs, we comparatively investigated the genome sequences of the Solanaceae species potato (Solanum tuberosum), tomato (Solanum lycopersicum), wild tomato (Solanum pennellii), and two pepper cultivars (Capsicum annuum). Based on 8.5 Gbp sequence data, we annotated 82 983 SINE copies belonging to 10 families and subfamilies on a base pair level. Solanaceae SINEs are dispersed over all chromosomes with enrichments in distal regions. Depending on the genome assemblies and gene predictions, 30% of all SINE copies are associated with genes, particularly frequent in introns and untranslated regions (UTRs). The close association with genes is family specific. More than 10% of all genes annotated in the Solanaceae species investigated contain at least one SINE insertion, and we found genes harbouring up to 16 SINE copies. We demonstrate the involvement of SINEs in gene and genome evolution including the donation of splice sites, start and stop codons and exons to genes, enlargement of introns and UTRs, generation of tandem-like duplications and transduction of adjacent sequence regions. © 2016 The Authors The Plant Journal © 2016 John Wiley & Sons Ltd.
Cell proliferation control by Notch signalling during imaginal discs development in Drosophila
Directory of Open Access Journals (Sweden)
Carlos Estella
2015-02-01
Full Text Available The Notch signalling pathway is evolutionary conserved and participates in numerous developmental processes, including the control of cell proliferation. However, Notch signalling can promote or restrain cell division depending on the developmental context, as has been observed in human cancer where Notch can function as a tumor suppressor or an oncogene. Thus, the outcome of Notch signalling can be influenced by the cross-talk between Notch and other signalling pathways. The use of model organisms such as Drosophila has been proven to be very valuable to understand the developmental role of the Notch pathway in different tissues and its relationship with other signalling pathways during cell proliferation control. Here we review recent studies in Drosophila that shed light in the developmental control of cell proliferation by the Notch pathway in different contexts such as the eye, wing and leg imaginal discs. We also discuss the autonomous and non-autonomous effects of the Notch pathway on cell proliferation and its interactions with different signalling pathways.
Zhang, W.; Liu, T.; Xi, A.; Wang, Y. N.
2018-06-01
This paper is focused on the resonant responses and chaotic dynamics of a composite laminated circular cylindrical shell with radially pre-stretched membranes at both ends and clamped along a generatrix. Based on the two-degree-of-freedom non-autonomous nonlinear equations of this system, the method of multiple scales is employed to obtain the four-dimensional nonlinear averaged equation. The resonant case considered here is the primary parametric resonance-1/2 subharmonic resonance and 1:1 internal resonance. Corresponding to several selected parameters, the frequency-response curves are obtained. From the numerical results, we find that the hardening-spring-type behaviors and jump phenomena are exhibited. The jump phenomena also occur in the amplitude curves of the temperature parameter excitation. Moreover, it is found that the temperature parameter excitation, the coupling degree of two order modes and the detuning parameters can effect the nonlinear oscillations of this system. The periodic and chaotic motions of the composite laminated circular cylindrical shell clamped along a generatrix are demonstrated by the bifurcation diagrams, the maximum Lyapunov exponents, the phase portraits, the waveforms, the power spectrums and the Poincaré map. The temperature parameter excitation shows that the Pomeau-Manneville type intermittent chaos occur under the certain initial conditions. It is also found that there exist the twin phenomena between the Pomeau-Manneville type intermittent chaos and the period-doubling bifurcation.
Xavier, Crislaine; Cabral-de-Mello, Diogo Cavalcanti; de Moura, Rita Cássia
2014-12-01
Cytogenetic studies of the Neotropical beetle genus Dichotomius (Scarabaeinae, Coleoptera) have shown dynamism for centromeric constitutive heterochromatin sequences. In the present work we studied the chromosomes and isolated repetitive sequences of Dichotomius schiffleri aiming to contribute to the understanding of coleopteran genome/chromosomal organization. Dichotomius schiffleri presented a conserved karyotype and heterochromatin distribution in comparison to other species of the genus with 2n = 18, biarmed chromosomes, and pericentromeric C-positive blocks. Similarly to heterochromatin distributional patterns, the highly and moderately repetitive DNA fraction (C 0 t-1 DNA) was detected in pericentromeric areas, contrasting with the euchromatic mapping of an isolated TE (named DsmarMITE). After structural analyses, the DsmarMITE was classified as a non-autonomous element of the type miniature inverted-repeat transposable element (MITE) with terminal inverted repeats similar to Mariner elements of insects from different orders. The euchromatic distribution for DsmarMITE indicates that it does not play a part in the dynamics of constitutive heterochromatin sequences.
Two new miniature inverted-repeat transposable elements in the genome of the clam Donax trunculus.
Šatović, Eva; Plohl, Miroslav
2017-10-01
Repetitive sequences are important components of eukaryotic genomes that drive their evolution. Among them are different types of mobile elements that share the ability to spread throughout the genome and form interspersed repeats. To broaden the generally scarce knowledge on bivalves at the genome level, in the clam Donax trunculus we described two new non-autonomous DNA transposons, miniature inverted-repeat transposable elements (MITEs), named DTC M1 and DTC M2. Like other MITEs, they are characterized by their small size, their A + T richness, and the presence of terminal inverted repeats (TIRs). DTC M1 and DTC M2 are 261 and 286 bp long, respectively, and in addition to TIRs, both of them contain a long imperfect palindrome sequence in their central parts. These elements are present in complete and truncated versions within the genome of the clam D. trunculus. The two new MITEs share only structural similarity, but lack any nucleotide sequence similarity to each other. In a search for related elements in databases, blast search revealed within the Crassostrea gigas genome a larger element sharing sequence similarity only to DTC M1 in its TIR sequences. The lack of sequence similarity with any previously published mobile elements indicates that DTC M1 and DTC M2 elements may be unique to D. trunculus.
A Generalised Approach to Petri Nets and Algebraic Specifications
International Nuclear Information System (INIS)
Sivertsen, Terje
1998-02-01
The present report represents a continuation of the work on Petri nets and algebraic specifications. The reported research has focused on generalising the approach introduced in HWR-454, with the aim of facilitating the translation of a wider class of Petri nets into algebraic specification. This includes autonomous Petri nets with increased descriptive power, as well as non-autonomous Petri nets allowing the modelling of systems (1) involving extensive data processing; (2) with transitions synchronized on external events; (3) whose evolutions are time dependent. The generalised approach has the important property of being modular in the sense that the translated specifications can be gradually extended to include data processing, synchronization, and timing. The report also discusses the relative merits of state-based and transition-based specifications, and includes a non-trivial case study involving automated proofs of a large number of interrelated theorems. The examples in the report illustrate the use of the new HRP Prover. Of particular importance in this context is the automatic transformation between state-based and transitionbased specifications. It is expected that the approach introduced in HWR-454 and generalised in the present report will prove useful in future work on combination of wide variety of specification techniques
On the nature of in vivo requirements for rde-4 in RNAi and developmental pathways in C. elegans.
Blanchard, Daniel; Parameswaran, Poornima; Lopez-Molina, Javier; Gent, Jonathan; Saynuk, Jamie Fleenor; Fire, Andrew
2011-01-01
C. elegans RDE-4 is a double-stranded RNA binding protein that has been shown to play a key role in response to foreign double-stranded RNA (dsRNA). We have used diverse tools for analysis of gene function to characterize the domain and organismal foci of RDE-4 action in C. elegans. First, we examined the focus of activity within the RDE-4 protein, by testing a series of RDE-4 deletion constructs for their ability to support dsRNA-triggered gene silencing. These assays indicated a molecular requirement for a linker region and the second dsRNA-binding domain of RDE-4, with ancillary contributions to function from the C and N terminal domains. Second, we used mosaic analysis to explore the cellular focus of action of RDE-4. These experiments indicated an ability of RDE-4 to function non-autonomously in foreign RNA responses. Third, we used growth under stressful conditions to search for evidence of an organismal focus of action for RDE-4 distinct from its role in response to foreign dsRNA. Propagation at high temperatures exposed a conditional requirement for RDE-4 for optimal growth and fertility, indicating at least under these conditions that RDE-4 can serve an essential role in C. elegans. © 2011 Landes Bioscience
Cantrell, John H; Adler, Laszlo; Yost, William T
2015-02-01
Traveling wave solutions of the nonlinear acoustic wave equation are obtained for the fundamental and second harmonic resonances of a fluid-filled cavity. The solutions lead to the development of a non-autonomous toy model for cavity oscillations. Application of the Melnikov method to the model equation predicts homoclinic bifurcation of the Smale horseshoe type leading to a cascade of period doublings with increasing drive displacement amplitude culminating in chaos. The threshold value of the drive displacement amplitude at tangency is obtained in terms of the acoustic drive frequency and fluid attenuation coefficient. The model prediction of subharmonic generation leading to chaos is validated from acousto-optic diffraction measurements in a water-filled cavity using a 5 MHz acoustic drive frequency and from the measured frequency spectrum in the bifurcation cascade regime. The calculated resonant threshold amplitude of 0.2 nm for tangency is consistent with values estimated for the experimental set-up. Experimental evidence for the appearance of a stable subharmonic beyond chaos is reported.
Frank, T. D.
2008-02-01
We discuss two central claims made in the study by Bassler et al. [K.E. Bassler, G.H. Gunaratne, J.L. McCauley, Physica A 369 (2006) 343]. Bassler et al. claimed that Green functions and Langevin equations cannot be defined for nonlinear diffusion equations. In addition, they claimed that nonlinear diffusion equations are linear partial differential equations disguised as nonlinear ones. We review bottom-up and top-down approaches that have been used in the literature to derive Green functions for nonlinear diffusion equations and, in doing so, show that the first claim needs to be revised. We show that the second claim as well needs to be revised. To this end, we point out similarities and differences between non-autonomous linear Fokker-Planck equations and autonomous nonlinear Fokker-Planck equations. In this context, we raise the question whether Bassler et al.’s approach to financial markets is physically plausible because it necessitates the introduction of external traders and causes. Such external entities can easily be eliminated when taking self-organization principles and concepts of nonextensive thermostatistics into account and modeling financial processes by means of nonlinear Fokker-Planck equations.
Machine-Vision Systems Selection for Agricultural Vehicles: A Guide
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Gonzalo Pajares
2016-11-01
Full Text Available Machine vision systems are becoming increasingly common onboard agricultural vehicles (autonomous and non-autonomous for different tasks. This paper provides guidelines for selecting machine-vision systems for optimum performance, considering the adverse conditions on these outdoor environments with high variability on the illumination, irregular terrain conditions or different plant growth states, among others. In this regard, three main topics have been conveniently addressed for the best selection: (a spectral bands (visible and infrared; (b imaging sensors and optical systems (including intrinsic parameters and (c geometric visual system arrangement (considering extrinsic parameters and stereovision systems. A general overview, with detailed description and technical support, is provided for each topic with illustrative examples focused on specific applications in agriculture, although they could be applied in different contexts other than agricultural. A case study is provided as a result of research in the RHEA (Robot Fleets for Highly Effective Agriculture and Forestry Management project for effective weed control in maize fields (wide-rows crops, funded by the European Union, where the machine vision system onboard the autonomous vehicles was the most important part of the full perception system, where machine vision was the most relevant. Details and results about crop row detection, weed patches identification, autonomous vehicle guidance and obstacle detection are provided together with a review of methods and approaches on these topics.
Xu, Xin; Zhang, Yun; Jasper, Jeff; Lykken, Erik; Alexander, Peter B; Markowitz, Geoffrey J; McDonnell, Donald P; Li, Qi-Jing; Wang, Xiao-Fan
2016-04-12
Triple-negative breast cancer (TNBC) presents a major challenge in the clinic due to its lack of reliable prognostic markers and targeted therapies. Accumulating evidence strongly supports the notion that microRNAs (miRNAs) are involved in tumorigenesis and could serve as biomarkers for diagnostic purposes. To identify miRNAs that functionally suppress metastasis of TNBC, we employed a concerted approach with selecting miRNAs that display differential expression profiles from bioinformatic analyses of breast cancer patient databases and validating top candidates with functional assays using breast cancer cell lines and mouse models. We have found that miR-148a exhibits properties as a tumor suppressor as its expression is inversely correlated with the ability of both human and mouse breast cancer cells to colonize the lung in mouse xenograft tumor models. Mechanistically, miR-148a appears to suppress the extravasation process of cancer cells, likely by targeting two genes WNT1 and NRP1 in a cell non-autonomous manner. Importantly, lower expression of miR-148a is detected in higher-grade tumor samples and correlated with increased likelihood to develop metastases and poor prognosis in subsets of breast cancer patients, particularly those with TNBC. Thus, miR-148a is functionally defined as a suppressor of breast cancer metastasis and may serve as a prognostic biomarker for this disease.
Microtubules Enable the Planar Cell Polarity of Airway Cilia
Vladar, Eszter K.; Bayly, Roy D.; Sangoram, Ashvin; Scott, Matthew P.; Axelrod, Jeffrey D.
2012-01-01
Summary Background Airway cilia must be physically oriented along the longitudinal tissue axis for concerted, directional motility that is essential for proper mucociliary clearance. Results We show that Planar Cell Polarity (PCP) signaling specifies directionality and orients respiratory cilia. Within all airway epithelial cells a conserved set of PCP proteins shows interdependent, asymmetric junctional localization; non-autonomous signaling coordinates polarization between cells; and a polarized microtubule (MT) network is likely required for asymmetric PCP protein localization. We find that basal bodies dock after polarity of PCP proteins is established, are polarized nearly simultaneously, and refinement of basal body/cilium orientation continues during airway epithelial development. Unique to mature multiciliated cells, we identify PCP-regulated, planar polarized MTs that originate from basal bodies and interact, via their plus ends, with membrane domains associated with the PCP proteins Frizzled and Dishevelled. Disruption of MTs leads to misoriented cilia. Conclusions A conserved PCP pathway orients airway cilia by communicating polarity information from asymmetric membrane domains at the apical junctions, through MTs, to orient the MT and actin based network of ciliary basal bodies below the apical surface. PMID:23122850
Centenarian offspring: a model for understanding longevity.
Balistreri, Carmela Rita; Candore, Giuseppina; Accardi, Giulia; Buffa, Silvio; Bulati, Matteo; Martorana, Adriana; Colonna-Romano, Giuseppina; Lio, Domenico; Caruso, Calogero
2014-01-01
A main objective of current medical research is to improve the life quality of elderly people as priority of the continuous increase of ageing population. This phenomenon implies several medical, economic and social problems because of dramatic increase in number of non autonomous individuals affected by various pathologies. Accordingly, the research interest is focused on understanding the biological mechanisms involved in determining the positive ageing phenotype, i.e. the centenarian phenotype. In achieving this goal the choice of an appropriate study models is fundamental. Centenarians have been used as an optimal model for successful ageing. However, this model shows several limitations, i.e. the selection of appropriate controls and the use itself of the centenarians as a suitable model for healthy ageing. Thus, the interest has been centered on centenarian offspring, healthy elderly people. They may represent a model for understanding exceptional longevity for the following reasons: they exhibit a protective genetic background, cardiovascular and immunological profile, as well as a reduced rate of cognitive decline than age-matched people without centenarian relatives. Several of these aspects are summarized in this review based on the literature and the results of our studies.
Experimental analysis of chaos in under actuated electromechanical systems
Energy Technology Data Exchange (ETDEWEB)
Gonzalez Hernandez, H. G. [Universidad la Salle, Mexico, D.F. (Mexico); Alvarez Gallegos, Jaime [Instituto Politecnico Nacional (Mexico); Alvarez Gallegos Joaquin [Centro de Investigacion Cientifica y de Educacion Superior de Ensenada, Ensenada, Baja California (Mexico)
2001-10-01
An under actuated system is a kind of non-autonomous robotic system in which there are more links than actuators. The complexity of the dynamical behavior of these systems allows a wide variety of steady-state responses. The reconstruction of attractors based on time series obtained from measurements of one of the variables of a two-link, planar, under actuated robot called Pendubot, is developed. Time-delay coordinates, average mutual information, and percentage of false nearest neighbors' methods are used to reconstruct the invariant sets. It is shown that, under the action of a periodic torque, the Pendubot can display a variety of steady-state dynamics, including strange attractors. [Spanish] Un sistema electromecanico subactuado es un tipo de sistema robotico no autonomo que cuenta con mas eslabones que actuadores. La complejidad del comportamiento dinamico de estos sistemas permite una gran variedad de respuestas en estado estacionario. En este trabajo se desarrolla la reconstruccion de atractores basada en series de tiempo obtenidas a partir de mediciones de una de las variables de un robot planar de dos grados de libertad subactuado llamado Pendubot. A fin de reconstruir los conjuntos invariantes, se utilizan tecnica como retraso de coordenadas, promedio de informacion mutua y porcentaje de falsos vecinos cercanos. Se muestra que bajo la accion de un torque periodico, el Pendubot puede desplegar una variedad de comportamientos dinamicos en estado estacionario incluyendo atractores extranos.
International Nuclear Information System (INIS)
Ye Min; Lu Jing; Zhang Wei; Ding Qian
2005-01-01
The present investigation deals with nonlinear dynamic behavior of a parametrically excited simply supported rectangular symmetric cross-ply laminated composite thin plate for the first time. The governing equation of motion for rectangular symmetric cross-ply laminated composite thin plate is derived by using von Karman equation. The geometric nonlinearity and nonlinear damping are included in the governing equations of motion. The Galerkin approach is used to obtain a two-degree-of-freedom nonlinear system under parametric excitation. The method of multiple scales is utilized to transform the second-order non-autonomous differential equations to the first-order averaged equations. Using numerical method, the averaged equations are analyzed to obtain the steady state bifurcation responses. The analysis of stability for steady state bifurcation responses in laminated composite thin plate is also given. Under certain conditions laminated composite thin plate may have two or multiple steady state bifurcation solutions. Jumping phenomenon occurs in the steady state bifurcation solutions. The chaotic motions of rectangular symmetric cross-ply laminated composite thin plate are also found by using numerical simulation. The results obtained here demonstrate that the periodic, quasi-periodic and chaotic motions coexist for a parametrically excited fore-edge simply supported rectangular symmetric cross-ply laminated composite thin plate under certain conditions
Directory of Open Access Journals (Sweden)
Rangwala Sanjida H
2010-03-01
Full Text Available Abstract Background Sadhu elements are non-autonomous retroposons first recognized in Arabidopsis thaliana. There is a wide degree of divergence among different elements, suggesting that these sequences are ancient in origin. Here we report the results of several lines of investigation into the genomic organization and evolutionary history of this element family. Results We present a classification scheme for Sadhu elements in A. thaliana, describing derivative elements related to the full-length elements we reported previously. We characterized Sadhu5 elements in a set of A. thaliana strains in order to trace the history of radiation in this subfamily. Sequences surrounding the target sites of different Sadhu insertions are consistent with mobilization by LINE retroelements. Finally, we identified Sadhu elements grouping into distinct subfamilies in two related species, Arabidopsis arenosa and Arabidopsis lyrata. Conclusions Our analyses suggest that the Sadhu retroelement family has undergone target primed reverse transcription-driven retrotransposition during the divergence of different A. thaliana strains. In addition, Sadhu elements can be found at moderate copy number in three distinct Arabidopsis species, indicating that the evolutionary history of these sequences can be traced back at least several millions of years.
OP9-Lhx2 stromal cells facilitate derivation of hematopoietic progenitors both in vitro and in vivo
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Xiaoli Chen
2015-09-01
Full Text Available Generating engraftable hematopoietic stem cells (HSCs from pluripotent stem cells (PSCs is an ideal approach for obtaining induced HSCs for cell therapy. However, the path from PSCs to robustly induced HSCs (iHSCs in vitro remains elusive. We hypothesize that the modification of hematopoietic niche cells by transcription factors facilitates the derivation of induced HSCs from PSCs. The Lhx2 transcription factor is expressed in fetal liver stromal cells but not in fetal blood cells. Knocking out Lhx2 leads to a fetal hematopoietic defect in a cell non-autonomous role. In this study, we demonstrate that the ectopic expression of Lhx2 in OP9 cells (OP9-Lhx2 accelerates the hematopoietic differentiation of PSCs. OP9-Lhx2 significantly increased the yields of hematopoietic progenitor cells via co-culture with PSCs in vitro. Interestingly, the co-injection of OP9-Lhx2 and PSCs into immune deficient mice also increased the proportion of hematopoietic progenitors via the formation of teratomas. The transplantation of phenotypic HSCs from OP9-Lhx2 teratomas but not from the OP9 control supported a transient repopulating capability. The upregulation of Apln gene by Lhx2 is correlated to the hematopoietic commitment property of OP9-Lhx2. Furthermore, the enforced expression of Apln in OP9 cells significantly increased the hematopoietic differentiation of PSCs. These results indicate that OP9-Lhx2 is a good cell line for regeneration of hematopoietic progenitors both in vitro and in vivo.
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Chrystian Junqueira Alves
2015-09-01
Full Text Available Schwann cells are the main source of paracrine support to motor neurons. Oxidative stress and mitochondrial dysfunction have been correlated to motor neuron death in Amyotrophic Lateral Sclerosis (ALS. Despite the involvement of Schwann cells in early neuromuscular disruption in ALS, detailed molecular events of a dying-back triggering are unknown. Sciatic nerves of presymptomatic (60-day-old SOD1G93A mice were submitted to a high-density oligonucleotide microarray analysis. DAVID demonstrated the deregulated genes related to death, stress and mitochondrion, which allowed the identification of Cell cycle, ErbB signaling, Tryptophan metabolism and Rig-I-like receptor signaling as the most representative KEGG pathways. The protein-protein interaction networks based upon deregulated genes have identified the top hubs (TRAF2, H2AFX, E2F1, FOXO3, MSH2, NGFR, TGFBR1 and bottlenecks (TRAF2, E2F1, CDKN1B, TWIST1, FOXO3. Schwann cells were enriched from the sciatic nerve of presymptomatic mice using flow cytometry cell sorting. qPCR showed the up regulated (Ngfr, Cdnkn1b, E2f1, Traf2 and Erbb3, H2afx, Cdkn1a, Hspa1, Prdx, Mapk10 and down-regulated (Foxo3, Mtor genes in the enriched Schwann cells. In conclusion, molecular analyses in the presymptomatic sciatic nerve demonstrated the involvement of death, oxidative stress, and mitochondrial pathways in the Schwann cell non-autonomous mechanisms in the early stages of ALS.
Zoeller, Ludwig
2016-04-01
such landforms could persist and develop longer and were uplifted only during the Tertiary and Quaternary, more or less coeval with the development of the Central European Rift System. The Upper Cretaceous basin inversion strongly influenced the present-day macrorelief east of the geomorphologic diagonal whereas west of it the macrorelief was shaped by younger morphotectonic activities. This hypothesis will be discussed with respect to recent tectonic models on the collision history of Africa and Europe, the impingement of the thinned Central European crust, and the rotating relative drifting direction of Africa and the Adriatic plate with respect to the Eurasian plate (Kley & Voigt 2008). NW-SE structures may have been revived by Quaternary glacial isostatic processes and even by historical earthquakes. References: von Eynatten, H. et al., (2008), Int J Earth Sci (Geol Rundsch) 97:1315-1330 Kley, J. & Voigt, T., (2008), Geology 36:839-842
Fleitout, L.; Garaud, J.; Cailletaud, G.; Vigny, C.; Simons, W. J.; Ambrosius, B. A.; Trisirisatayawong, I.; Satirapod, C.; Geotecdi Song
2011-12-01
asthenosphere are consistent with a Burger rheology with a transient creep represented by a Kelvin-Voigt element with a viscosity of 3.1018Pas and μ Kelvin}=μ {elastic/3. A second Kelvin-Voigt element with very limited amplitude may explain some characteristics of the short time-scale signal. The viscosity of the low viscosity wedge is also of the order of 3. 1018 Pas. The near-field displacements are not explained by viscoelastic relaxation and post-seismic slip on the fault plane (15% of the cosismic slip) occured in the months after the earthquakes. These large post-seismic deformations affect the deviatoric stresses in the whole Sunda-block. They also imply sizable far-field interseismic deformations.
Fleitout, L.; Trubienko, O.; Garaud, J.; Vigny, C.; Cailletaud, G.; Simons, W. J.; Satirapod, C.; Shestakov, N.
2012-12-01
A 3D finite element code (Zebulon-Zset) is used to model deformations through the seismic cycle in the areas surrounding the last three large subduction earthquakes: Sumatra, Japan and Chile. The mesh featuring a broad spherical shell portion with a viscoelastic asthenosphere is refined close to the subduction zones. The model is constrained by 6 years of postseismic data in Sumatra area and over a year of data for Japan and Chile plus preseismic data in the three areas. The coseismic displacements on the subduction plane are inverted from the coseismic displacements using the finite element program and provide the initial stresses. The predicted horizontal postseismic displacements depend upon the thicknesses of the elastic plate and of the low viscosity asthenosphere. Non-dimensionalized by the coseismic displacements, they present an almost uniform value between 500km and 1500km from the trench for elastic plates 80km thick. The time evolution of the velocities is function of the creep law (Maxwell, Burger or power-law creep). Moreover, the forward models predict a sizable far-field subsidence, also with a spatial distribution which varies with the geometry of the asthenosphere and lithosphere. Slip on the subduction interface does not induce such a subsidence. The observed horizontal velocities, divided by the coseismic displacement, present a similar pattern as function of time and distance from trench for the three areas, indicative of similar lithospheric and asthenospheric thicknesses and asthenospheric viscosity. This pattern cannot be fitted with power-law creep in the asthenosphere but indicates a lithosphere 60 to 90km thick and an asthenosphere of thickness of the order of 100km with a burger rheology represented by a Kelvin-Voigt element with a viscosity of 3.1018Pas and μKelvin=μelastic/3. A second Kelvin-Voigt element with very limited amplitude may explain some characteristics of the short time-scale signal. The postseismic subsidence is
Análisis microestructural comparativo (difracción de rayos X y FESEM en sepiolita
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Bastida, J.
2006-10-01
Full Text Available Microstructural size characteristics of a reference sepiolite during grinding in a vibratory cup mill have been studied through X-ray diffraction (XRD line broadening analysis, with Warren- Averbach and Voigt function method in different diffraction directions and through field emission electron microscope (FESEM images and surface area measurements. The second XRD method seem s to be more useful for sepiolite analysis because of the difficulty of the Warren – Averbach to be used ; it provides the general trends for crystallite size and strain evolution along the comminution by vibrating dry- milling of sepiolite. A previous morphological modelling allows the interpretation of FESEM images. The apparent crystallite sizes determined via the X- Ray diffraction are in agreement with measurements of widths of the prevalent pinacoidal and prismatic prevalent faces ( of {110}y {010} forms on FESEM images. The found ranges for FESEM width values in rectangular shaped faces includes the XRD crystallite sizes found for [110] and [010] directions o diffarction. So the observed decreasing of XRD crystallite size trough comminution is in agreement with FESEM micromorphological and surface area measurements.
Se practica el análisis microestructural por DRX (métodos de Warren- Averbach y de la función de Voigt para diferentes direcciones en una sepiolita de referencia sometida a molienda en molino de giro excéntrico de alta energía. El segundo método se muestra más adecuado para el estudio de sepiolita, dadas las características de su difractograma y pone de manifiesto eficazmente las pautas generales de disminución de tamaño de cristalito y de aumento de distorsiones de red durante el proceso. La realización de una modelización morfológica previa permite la identificación de formas cristalinas en imágenes de FESEM, así como el encuadre de los datos de DRX, en la observación microscópica. Los tamaños aparentes de cristalito medidos
Energy Technology Data Exchange (ETDEWEB)
Caravaca, M A; Mino, J C; Perez, V J [Departamento de Fisico-Quimica, Facultad de Ingenieria, UNNE, Avenida Las Heras 727, CP 3500, Resistencia (Argentina); Casali, R A; Ponce, C A [Departamento de Fisica, Facultad de Ciencias Exactas y Naturales y Agrimensura UNNE, Avenida Libertad 5600, CP 3400, Corrientes (Argentina)
2009-01-07
In this work, we study theoretically the elastic properties of the orthorhombic (Pnma) high-pressure phase of IV-B group oxides: titania, zirconia and hafnia. By means of the self-consistent SIESTA code, pseudopotentials, density functional theory in the LDA and GGA approximations, the total energies, hydrostatic pressures and stress tensor components are calculated. From the stress-strain relationships, in the linear regime, the elastic constants C{sub ij} are determined. Derived elastic constants, such as bulk, Young's and shear modulus, Poisson coefficient and brittle/ductile behavior are estimated with the polycrystalline approach, using Voigt-Reuss-Hill theories. We have found that C{sub 11}, C{sub 22} and C{sub 33} elastic constants of hafnia and zirconia show increased strength with respect to the experimental values of the normal phase, P 2{sub 1}/c. A similar situation applies to titania if these constants are compared with its normal phase, rutile. However, shear elastic constants C{sub 44}, C{sub 55} and C{sub 66} are similar to the values found in the normal phase. This fact increases the compound anisotropy as well as its ductile behavior. The dependence of unit-cell volumes under hydrostatic pressures is also analyzed. P-V data, fitted to third-order Birch-Murnaghan equations of state, provide the bulk modulus B{sub 0} and its pressure derivatives B'{sub 0}. In this case, LDA estimations show good agreement with respect to recent measured bulk moduli of ZrO{sub 2} and HfO{sub 2}. Thermo-acoustic properties, e.g. the propagation speed of transverse, longitudinal elastic waves together with associated Debye temperatures, are also estimated.
International Nuclear Information System (INIS)
Schreier, Franz; Gimeno García, Sebastián; Hedelt, Pascal; Hess, Michael; Mendrok, Jana; Vasquez, Mayte; Xu, Jian
2014-01-01
A suite of programs for high resolution infrared-microwave atmospheric radiative transfer modeling has been developed with emphasis on efficient and reliable numerical algorithms and a modular approach appropriate for simulation and/or retrieval in a variety of applications. The Generic Atmospheric Radiation Line-by-line Infrared Code — GARLIC — is suitable for arbitrary observation geometry, instrumental field-of-view, and line shape. The core of GARLIC's subroutines constitutes the basis of forward models used to implement inversion codes to retrieve atmospheric state parameters from limb and nadir sounding instruments. This paper briefly introduces the physical and mathematical basics of GARLIC and its descendants and continues with an in-depth presentation of various implementation aspects: An optimized Voigt function algorithm combined with a two-grid approach is used to accelerate the line-by-line modeling of molecular cross sections; various quadrature methods are implemented to evaluate the Schwarzschild and Beer integrals; and Jacobians, i.e. derivatives with respect to the unknowns of the atmospheric inverse problem, are implemented by means of automatic differentiation. For an assessment of GARLIC's performance, a comparison of the quadrature methods for solution of the path integral is provided. Verification and validation are demonstrated using intercomparisons with other line-by-line codes and comparisons of synthetic spectra with spectra observed on Earth and from Venus. - Highlights: • High resolution infrared-microwave radiative transfer model. • Discussion of algorithmic and computational aspects. • Jacobians by automatic/algorithmic differentiation. • Performance evaluation by intercomparisons, verification, validation