... varicose veins, and taking birth control pills or hormone replacement can increase your risk) Being born with defective valves Obesity Pregnancy History of blood clots in your legs Standing or ...
... stripping; Venous reflux - vein stripping; Venous ulcer - veins Patient Instructions Surgical wound care - open Varicose veins - what to ask your doctor Images Circulatory system References American Family Physician. Management of varicose veins. www.aafp.org/afp/2008/ ...
SU(1,2) invariance in two-dimensional oscillator
Energy Technology Data Exchange (ETDEWEB)
Krivonos, Sergey [Bogoliubov Laboratory of Theoretical Physics,Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nersessian, Armen [Yerevan State University,1 Alex Manoogian St., Yerevan, 0025 (Armenia); Tomsk Polytechnic University,Lenin Ave. 30, 634050 Tomsk (Russian Federation)
2017-02-01
Performing the Hamiltonian analysis we explicitly established the canonical equivalence of the deformed oscillator, constructed in arXiv:1607.03756, with the ordinary one. As an immediate consequence, we proved that the SU(1,2) symmetry is the dynamical symmetry of the ordinary two-dimensional oscillator. The characteristic feature of this SU(1,2) symmetry is a non-polynomial structure of its generators written in terms of the oscillator variables.
Two-dimensional generalized harmonic oscillators and their Darboux partners
International Nuclear Information System (INIS)
Schulze-Halberg, Axel
2011-01-01
We construct two-dimensional Darboux partners of the shifted harmonic oscillator potential and of an isotonic oscillator potential belonging to the Smorodinsky–Winternitz class of superintegrable systems. The transformed solutions, their potentials and the corresponding discrete energy spectra are computed in explicit form. (paper)
Coulomb-oscillator duality and 5-dimensional Coulomb problem
Karayan, K H
2003-01-01
It is shown that the Hurwitz transformation connects the eight-dimensional oscillator problem with the five-dimensional Coulomb problem. The hyperspherical and parabolic coordinates are applied for analyzing the five-dimensional Coulomb problem. We calculate the spherical and parabolic bases for this system, derive the Park's and Tarter's representations for the coefficients of the spherical-parabolic and parabolic-spherical interbasis expansions
An exactly solvable three-dimensional nonlinear quantum oscillator
Energy Technology Data Exchange (ETDEWEB)
Schulze-Halberg, A. [Department of Mathematics and Actuarial Science, Indiana University Northwest, 3400 Broadway, Gary, Indiana 46408 (United States); Morris, J. R. [Department of Physics, Indiana University Northwest, 3400 Broadway, Gary, Indiana 46408 (United States)
2013-11-15
Exact analytical, closed-form solutions, expressed in terms of special functions, are presented for the case of a three-dimensional nonlinear quantum oscillator with a position dependent mass. This system is the generalization of the corresponding one-dimensional system, which has been the focus of recent attention. In contrast to other approaches, we are able to obtain solutions in terms of special functions, without a reliance upon a Rodrigues-type of formula. The wave functions of the quantum oscillator have the familiar spherical harmonic solutions for the angular part. For the s-states of the system, the radial equation accepts solutions that have been recently found for the one-dimensional nonlinear quantum oscillator, given in terms of associated Legendre functions, along with a constant shift in the energy eigenvalues. Radial solutions are obtained for all angular momentum states, along with the complete energy spectrum of the bound states.
An exactly solvable three-dimensional nonlinear quantum oscillator
International Nuclear Information System (INIS)
Schulze-Halberg, A.; Morris, J. R.
2013-01-01
Exact analytical, closed-form solutions, expressed in terms of special functions, are presented for the case of a three-dimensional nonlinear quantum oscillator with a position dependent mass. This system is the generalization of the corresponding one-dimensional system, which has been the focus of recent attention. In contrast to other approaches, we are able to obtain solutions in terms of special functions, without a reliance upon a Rodrigues-type of formula. The wave functions of the quantum oscillator have the familiar spherical harmonic solutions for the angular part. For the s-states of the system, the radial equation accepts solutions that have been recently found for the one-dimensional nonlinear quantum oscillator, given in terms of associated Legendre functions, along with a constant shift in the energy eigenvalues. Radial solutions are obtained for all angular momentum states, along with the complete energy spectrum of the bound states
Low-dimensional maps for piecewise smooth oscillators
Pavlovskaia, Ekaterina; Wiercigroch, Marian
2007-09-01
Dynamics of the piecewise smooth nonlinear oscillators is considered, for which, general methodology of reducing multidimensional flows to low-dimensional maps is proposed. This includes a definition of piecewise smooth oscillator and creation of a global iterative map providing an exact solution. The global map is comprised of local maps, which are constructed in the smooth sub-regions of phase space. To construct this low-dimensional map, it is proposed to monitor the points of intersections of a chosen boundary between smooth subspaces by a trajectory. The dimension reduction is directly related to the dimension of the chosen boundary, and the lower its dimension is, the larger dimension reduction can be achieved. Full details are given for a drifting impact oscillator, where the five-dimensional flow is reduced to one-dimensional (1D) approximate analytical map. First an exact two-dimensional map has been formulated and analysed. A further reduction to 1D approximate map is introduced and discussed. Standard nonlinear dynamic analysis reveals a complex behaviour ranging from periodic oscillations to chaos, and co-existence of multiple attractors. Accuracy of the constructed maps is examined by comparing with the exact solutions for a wide range of the system parameters.
Statistical mechanics of quantum one-dimensional damped harmonic oscillator
International Nuclear Information System (INIS)
Borges, E.N.M.; Borges, O.N.; Ribeiro, L.A.A.
1985-01-01
We calculate the thermal correlation functions of the one-dimensional damped harmonic oscillator in contact with a reservoir, in an exact form by applying Green's function method. In this way the thermal fluctuations are incorporated in the Caldirola-Kanai Hamiltonian
Dimensionality reduction for the analysis of brain oscillations.
Haufe, Stefan; Dähne, Sven; Nikulin, Vadim V
2014-11-01
Neuronal oscillations have been shown to be associated with perceptual, motor and cognitive brain operations. While complex spatio-temporal dynamics are a hallmark of neuronal oscillations, they also represent a formidable challenge for the proper extraction and quantification of oscillatory activity with non-invasive recording techniques such as EEG and MEG. In order to facilitate the study of neuronal oscillations we present a general-purpose pre-processing approach, which can be applied for a wide range of analyses including but not restricted to inverse modeling and multivariate single-trial classification. The idea is to use dimensionality reduction with spatio-spectral decomposition (SSD) instead of the commonly and almost exclusively used principal component analysis (PCA). The key advantage of SSD lies in selecting components explaining oscillations-related variance instead of just any variance as in the case of PCA. For the validation of SSD pre-processing we performed extensive simulations with different inverse modeling algorithms and signal-to-noise ratios. In all these simulations SSD invariably outperformed PCA often by a large margin. Moreover, using a database of multichannel EEG recordings from 80 subjects we show that pre-processing with SSD significantly increases the performance of single-trial classification of imagined movements, compared to the classification with PCA pre-processing or without any dimensionality reduction. Our simulations and analysis of real EEG experiments show that, while not being supervised, the SSD algorithm is capable of extracting components primarily relating to the signal of interest often using as little as 20% of the data variance, instead of > 90% variance as in case of PCA. Given its ease of use, absence of supervision, and capability to efficiently reduce the dimensionality of multivariate EEG/MEG data, we advocate the application of SSD pre-processing for the analysis of spontaneous and induced neuronal
Oscillation of Two-Dimensional Neutral Delay Dynamic Systems
Directory of Open Access Journals (Sweden)
Xinli Zhang
2013-01-01
Full Text Available We consider a class of nonlinear two-dimensional dynamic systems of the neutral type (x(t-a(tx(τ1(tΔ=p(tf1(y(t, yΔ(t=-q(tf2(x(τ2(t. We obtain sufficient conditions for all solutions of the system to be oscillatory. Our oscillation results when a(t=0 improve the oscillation results for dynamic systems on time scales that have been established by Fu and Lin (2010, since our results do not restrict to the case where f(u=u. Also, as a special case when =ℝ, our results do not require an to be a positive real sequence. Some examples are given to illustrate the main results.
Exact semiclassical expansions for one-dimensional quantum oscillators
Energy Technology Data Exchange (ETDEWEB)
Delabaere, E. [UMR CNRS J. A. Dieudonne No. 6621, University of Nice, 06108 Nice Cedex 2 (France); Dillinger, H.; Pham, F. [University of Nice, Department of Maths, UMR CNRS J.A. Dieudonne No. 6621, 06108 Nice Cedex 2 (France)
1997-12-01
A set of rules is given for dealing with WKB expansions in the one-dimensional analytic case, whereby such expansions are not considered as approximations but as exact encodings of wave functions, thus allowing for analytic continuation with respect to whichever parameters the potential function depends on, with an exact control of small exponential effects. These rules, which include also the case when there are double turning points, are illustrated on various examples, and applied to the study of bound state or resonance spectra. In the case of simple oscillators, it is thus shown that the Rayleigh{endash}Schr{umlt o}dinger series is Borel resummable, yielding the exact energy levels. In the case of the symmetrical anharmonic oscillator, one gets a simple and rigorous justification of the Zinn-Justin quantization condition, and of its solution in terms of {open_quotes}multi-instanton expansions.{close_quotes} {copyright} {ital 1997 American Institute of Physics.}
Higher dimensional models of cross-coupled oscillators and application to design
Elwakil, Ahmed S.
2010-06-01
We present four-dimensional and five-dimensional models for classical cross-coupled LC oscillators. Using these models, sinusoidal oscillation condition, frequency and amplitude can be found. Further, undesired behaviors such as relaxation-mode oscillations and latchup can be explained and detected. A simple graphical design procedure is also described. © 2010 World Scientific Publishing Company.
Quantum oscillations in quasi-two-dimensional conductors
Galbova, O
2002-01-01
The electronic absorption of sound waves in quasi-two-dimensional conductors in strong magnetic fields, is investigated theoretically. A longitudinal acoustic wave, propagating along the normal n-> to the layer of quasi-two-dimensional conductor (k-> = left brace 0,0,k right brace; u-> = left brace 0,0,u right brace) in magnetic field (B-> = left brace 0, 0, B right brace), is considered. The quasiclassical approach for this geometry is of no interest, due to the absence of interaction between electromagnetic and acoustic waves. The problem is of interest in strong magnetic field when quantization of the charge carriers energy levels takes place. The quantum oscillations in the sound absorption coefficient, as a function of the magnetic field, are theoretically observed. The experimental study of the quantum oscillations in quasi-two-dimensional conductors makes it possible to solve the inverse problem of determining from experimental data the extrema closed sections of the Fermi surface by a plane p sub z = ...
... Examples of these factors include family history, older age, gender, pregnancy, overweight or obesity , lack of movement, and leg trauma. Varicose veins are treated with lifestyle changes and medical procedures. The goals of treatment are to relieve symptoms, prevent complications, and improve ...
... stagnate (pool) in the legs, leading to high blood pressure in the leg veins. This may result in further enlargement of the ... you can help delay the development of varicose veins or keep them from progressing. Some ... pressure under control. • To temporarily relieve symptoms, lie down ...
Optimal synchronization of Kuramoto oscillators: A dimensional reduction approach
Pinto, Rafael S.; Saa, Alberto
2015-12-01
A recently proposed dimensional reduction approach for studying synchronization in the Kuramoto model is employed to build optimal network topologies to favor or to suppress synchronization. The approach is based in the introduction of a collective coordinate for the time evolution of the phase locked oscillators, in the spirit of the Ott-Antonsen ansatz. We show that the optimal synchronization of a Kuramoto network demands the maximization of the quadratic function ωTL ω , where ω stands for the vector of the natural frequencies of the oscillators and L for the network Laplacian matrix. Many recently obtained numerical results can be reobtained analytically and in a simpler way from our maximization condition. A computationally efficient hill climb rewiring algorithm is proposed to generate networks with optimal synchronization properties. Our approach can be easily adapted to the case of the Kuramoto models with both attractive and repulsive interactions, and again many recent numerical results can be rederived in a simpler and clearer analytical manner.
Tuset-Sanchis, Luis; Castro-Palacio, Juan C.; Gómez-Tejedor, José A.; Manjón, Francisco J.; Monsoriu, Juan A.
2015-01-01
A smartphone acceleration sensor is used to study two-dimensional harmonic oscillations. The data recorded by the free android application, Accelerometer Toy, is used to determine the periods of oscillation by graphical analysis. Different patterns of the Lissajous curves resulting from the superposition of harmonic motions are illustrated for…
Supersymmetry and the constants of motion of the two-dimensional isotropic harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Torres del Castillo, G.F. [Departamento de Fisica Matematica, Instituto de Ciencias, Universidad Autonoma de Puebla, 72570 Puebla (Mexico); Tepper G, T. [Escuela de Ciencias, Departamento de Fisica y Matematicas, Universidad de Las Americas-Puebla, Santa Catarina Martir, 72820 Cholula, Puebla (Mexico)
2002-07-01
It is shown that the constants of motion of the two-dimensional isotropic harmonic oscillator not related to the rotational invariance of the Hamiltonian can be derived using the ideas of supersymmetric quantum mechanics. (Author)
Supersymmetry and the constants of motion of the two-dimensional isotropic harmonic oscillator
International Nuclear Information System (INIS)
Torres del Castillo, G.F.; Tepper G, T.
2002-01-01
It is shown that the constants of motion of the two-dimensional isotropic harmonic oscillator not related to the rotational invariance of the Hamiltonian can be derived using the ideas of supersymmetric quantum mechanics. (Author)
International Nuclear Information System (INIS)
Wang, C M; Lei, X L
2014-01-01
We study dc-current effects on the magnetoresistance oscillation in a two-dimensional electron gas with Rashba spin-orbit coupling, using the balance-equation approach to nonlinear magnetotransport. In the weak current limit the magnetoresistance exhibits periodical Shubnikov-de Haas oscillation with changing Rashba coupling strength for a fixed magnetic field. At finite dc bias, the period of the oscillation halves when the interbranch contribution to resistivity dominates. With further increasing current density, the oscillatory resistivity exhibits phase inversion, i.e., magnetoresistivity minima (maxima) invert to maxima (minima) at certain values of the dc bias, which is due to the current-induced magnetoresistance oscillation. (paper)
Chimera states in two-dimensional networks of locally coupled oscillators
Kundu, Srilena; Majhi, Soumen; Bera, Bidesh K.; Ghosh, Dibakar; Lakshmanan, M.
2018-02-01
Chimera state is defined as a mixed type of collective state in which synchronized and desynchronized subpopulations of a network of coupled oscillators coexist and the appearance of such anomalous behavior has strong connection to diverse neuronal developments. Most of the previous studies on chimera states are not extensively done in two-dimensional ensembles of coupled oscillators by taking neuronal systems with nonlinear coupling function into account while such ensembles of oscillators are more realistic from a neurobiological point of view. In this paper, we report the emergence and existence of chimera states by considering locally coupled two-dimensional networks of identical oscillators where each node is interacting through nonlinear coupling function. This is in contrast with the existence of chimera states in two-dimensional nonlocally coupled oscillators with rectangular kernel in the coupling function. We find that the presence of nonlinearity in the coupling function plays a key role to produce chimera states in two-dimensional locally coupled oscillators. We analytically verify explicitly in the case of a network of coupled Stuart-Landau oscillators in two dimensions that the obtained results using Ott-Antonsen approach and our analytical finding very well matches with the numerical results. Next, we consider another type of important nonlinear coupling function which exists in neuronal systems, namely chemical synaptic function, through which the nearest-neighbor (locally coupled) neurons interact with each other. It is shown that such synaptic interacting function promotes the emergence of chimera states in two-dimensional lattices of locally coupled neuronal oscillators. In numerical simulations, we consider two paradigmatic neuronal oscillators, namely Hindmarsh-Rose neuron model and Rulkov map for each node which exhibit bursting dynamics. By associating various spatiotemporal behaviors and snapshots at particular times, we study the chimera
Yuan, Fang; Wang, Guangyi; Wang, Xiaowei
2017-03-01
In this paper, smooth curve models of meminductor and memcapacitor are designed, which are generalized from a memristor. Based on these models, a new five-dimensional chaotic oscillator that contains a meminductor and memcapacitor is proposed. By dimensionality reducing, this five-dimensional system can be transformed into a three-dimensional system. The main work of this paper is to give the comparisons between the five-dimensional system and its dimensionality reduction model. To investigate dynamics behaviors of the two systems, equilibrium points and stabilities are analyzed. And the bifurcation diagrams and Lyapunov exponent spectrums are used to explore their properties. In addition, digital signal processing technologies are used to realize this chaotic oscillator, and chaotic sequences are generated by the experimental device, which can be used in encryption applications.
Current-induced magnetoresistance oscillations in two-dimensional electron systems
Lei, X. L.
2006-01-01
Electric current-induced magnetoresistance oscillations recently discovered in two-dimensional electron systems are analyzed using a microscopic scheme for nonlinear magnetotransport direct controlled by the current. The magnetoresistance oscillations are shown to result from drift-motion assisted electron scatterings between Landau levels. The theoretical predictions not only reproduce all the main features observed in the experiments but also disclose other details of the phenomenon.
Commensurability oscillations by snake-orbit magnetotransport in two-dimensional electron gases
Leuschner, A.; Schluck, J.; Cerchez, M.; Heinzel, T.; Pierz, K.; Schumacher, H. W.
2017-04-01
Commensurate magnetoresistance periodic oscillations generated by transversal electron snake orbits are found experimentally. A two-dimensional electron gas is exposed to a magnetic field that changes sign along the current longitudinal direction and is homogeneous in the transverse direction. The change in sign of the magnetic field directs the electron flow along the transversal direction, in snake orbits. This generates resistance oscillations with a predictable periodicity that is commensurate with the width of the electron gas. Numerical simulations are used to reveal the character of the oscillations.
Quantized impedance dealing with the damping behavior of the one-dimensional oscillator
Directory of Open Access Journals (Sweden)
Jinghao Zhu
2015-11-01
Full Text Available A quantized impedance is proposed to theoretically establish the relationship between the atomic eigenfrequency and the intrinsic frequency of the one-dimensional oscillator in this paper. The classical oscillator is modified by the idea that the electron transition is treated as a charge-discharge process of a suggested capacitor with the capacitive energy equal to the energy level difference of the jumping electron. The quantized capacitance of the impedance interacting with the jumping electron can lead the resonant frequency of the oscillator to the same as the atomic eigenfrequency. The quantized resistance reflects that the damping coefficient of the oscillator is the mean collision frequency of the transition electron. In addition, the first and third order electric susceptibilities based on the oscillator are accordingly quantized. Our simulation of the hydrogen atom emission spectrum based on the proposed method agrees well with the experimental one. Our results exhibits that the one-dimensional oscillator with the quantized impedance may become useful in the estimations of the refractive index and one- or multi-photon absorption coefficients of some nonmagnetic media composed of hydrogen-like atoms.
Friedel oscillations in one-dimensional metals: From Luttinger's theorem to the Luttinger liquid
International Nuclear Information System (INIS)
Vieira, Daniel; Freire, Henrique J.P.; Campo, V.L.; Capelle, K.
2008-01-01
Charge density and magnetization density profiles of one-dimensional metals are investigated by two complementary many-body methods: numerically exact (Lanczos) diagonalization, and the Bethe-Ansatz local-density approximation with and without a simple self-interaction correction. Depending on the magnetization of the system, local approximations reproduce different Fourier components of the exact Friedel oscillations
Varicose veins show enhanced chemokine expression.
Solá, L del Rio; Aceves, M; Dueñas, A I; González-Fajardo, J A; Vaquero, C; Crespo, M Sanchez; García-Rodríguez, C
2009-11-01
Leucocyte infiltration in the wall of varicose veins has been reported previously. This study was designed to investigate the expression of pro-inflammatory cytokines and chemokines in control and in patients with varicose veins and to test the effect of treating varicose vein patients with acetylsalicylic acid (ASA) on cytokine expression prior to removal of varices. Sections of vein were removed during operation from both patient groups, and ribonuclease protection assays (RPAs) were performed to assess the expression of chemokines. Group I included non-varicose saphenous veins from healthy patients undergoing amputation for trauma. Varicose veins were obtained from patients with primary varicose undergoing surgical treatment who received no drug (group II) or treatment with 300 mg day(-1) of ASA for 15 days before surgery (group III). Non-varicose veins constitutively expressed low levels of monocyte-chemoattractant protein (MCP-1) and interleukin (IL)-8 mRNA. Varicose veins had a distinct chemokine expression pattern, since significant up-regulation of MCP-1 and IL-8 and a marked expression of IP-10, RANTES, MIP-1alpha and MIP-1beta mRNA were detected. Removal of the endothelium did not alter this pattern. Varicose veins obtained from patients treated with ASA showed a consistent decrease in chemokine expression, although it did not reach statistical significance. Varicose veins showed increased expression of several chemokines compared to control veins. A non-significant reduction of activation was observed following treatment with ASA for 15 days.
Compact modes in quasi one dimensional coupled magnetic oscillators
López-González, Dany; Molina, Mario I.
2017-11-01
In this work we study analytically and numerically the spectrum and localization properties of three quasi-one-dimensional (ribbons) split-ring resonator arrays which possess magnetic flatbands, namely, the stub, Lieb and kagome lattices, and how their spectra are affected by the presence of perturbations that break the delicate geometrical interference needed for a magnetic flatband to exist. We find that the stub and Lieb ribbons are stable against the three types of perturbations considered here, while the kagome ribbon is, in general, unstable. When losses are incorporated, all flatbands remain dispersionless but become complex, with the kagome ribbon exhibiting the highest loss rate. The stability of flatband modes of certain split-ring resonator arrays suggests that they could be used as components of future stable magnetic storage devices.
International Nuclear Information System (INIS)
Wang Qing; Hou Yu-Long; Jing Jian; Long Zheng-Wen
2014-01-01
In this paper, we study symmetrical properties of two-dimensional (2D) screened Dirac Hydrogen atom and isotropic harmonic oscillator with scalar and vector potentials of equal magnitude (SVPEM). We find that it is possible for both cases to preserve so(3) and su(2) dynamical symmetries provided certain conditions are satisfied. Interestingly, the conditions for preserving these dynamical symmetries are exactly the same as non-relativistic screened Hydrogen atom and screened isotropic oscillator preserving their dynamical symmetries. Some intuitive explanations are proposed. (general)
On oscillation and nonoscillation of two-dimensional linear differential systems
Czech Academy of Sciences Publication Activity Database
Lomtatidze, A.; Šremr, Jiří
2013-01-01
Roč. 20, č. 3 (2013), s. 573-600 ISSN 1072-947X Institutional support: RVO:67985840 Keywords : two-dimensional system of linear ODE * oscillation * nonoscillation Subject RIV: BA - General Mathematics Impact factor: 0.340, year: 2013 http://www.degruyter.com/view/j/gmj.2013.20.issue-3/gmj-2013-0025/gmj-2013-0025. xml ?format=INT
One dimensional Dirac-Moshinsky oscillator-like system and isospectral partners
International Nuclear Information System (INIS)
Contreras-Astorga, A
2015-01-01
Two different exactly solvable systems are constructed using the supersymmetric quantum mechanics formalism and a pseudoscalar one-dimensional version of the Dirac- Moshinsky oscillator as a departing system. One system is built using a first-order SUSY transformation. The second is obtained through the confluent supersymmetry algorithm. The two of them are explicitly designed to have the same spectrum as the departing system and pseudoscalar potentials. (paper)
A hidden non-Abelian monopole in a 16-dimensional isotropic harmonic oscillator
International Nuclear Information System (INIS)
Le, Van-Hoang; Nguyen, Thanh-Son; Phan, Ngoc-Hung
2009-01-01
We suggest one variant of generalization of the Hurwitz transformation by adding seven extra variables that allow an inverse transformation to be obtained. Using this generalized transformation we establish the connection between the Schroedinger equation of a 16-dimensional isotropic harmonic oscillator and that of a nine-dimensional hydrogen-like atom in the field of a monopole described by a septet of potential vectors in a non-Abelian model of 28 operators. The explicit form of the potential vectors and all the commutation relations of the algebra are given./
A hidden non-Abelian monopole in a 16-dimensional isotropic harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Le, Van-Hoang; Nguyen, Thanh-Son; Phan, Ngoc-Hung [Department of Physics, HCMC University of Pedagogy, 280 An Duong Vuong, Ward 10, Dist. 5, Ho Chi Minh City (Viet Nam)
2009-05-01
We suggest one variant of generalization of the Hurwitz transformation by adding seven extra variables that allow an inverse transformation to be obtained. Using this generalized transformation we establish the connection between the Schroedinger equation of a 16-dimensional isotropic harmonic oscillator and that of a nine-dimensional hydrogen-like atom in the field of a monopole described by a septet of potential vectors in a non-Abelian model of 28 operators. The explicit form of the potential vectors and all the commutation relations of the algebra are given./.
Self-oscillations of a two-dimensional shear flow with forcing and dissipation
López Zazueta, A.; Zavala Sansón, L.
2018-04-01
Two-dimensional shear flows continuously forced in the presence of dissipative effects are studied by means of numerical simulations. In contrast with most previous studies, the forcing is confined in a finite region, so the behavior of the system is characterized by the long-term evolution of the global kinetic energy. We consider regimes with 1 relevant regime is found for Reλ > 36, in which the energy maintains a regular oscillation around a reference value. The flow configuration is an elliptical vortex tilted with respect to the forcing axis, which oscillates steadily also. Second, the flow is allowed to develop two Kelvin-Helmholtz billows and eventually more complicated structures. The regimes of the one-vortex case are observed again, except for Reλ > 135. At these values, the energy oscillates chaotically as the two vortices merge, form dipolar structures, and split again, with irregular periodicity. The self-oscillations are explained as a result of the alternate competition between forcing and dissipation, which is verified by calculating the budget terms in the energy equation. The relevance of the forcing-vs.-dissipation competition is discussed for more general flow systems.
DEFF Research Database (Denmark)
Dahl, Jens Peder; Schleich, W. P.
2009-01-01
For a closed quantum system the state operator must be a function of the Hamiltonian. When the state is degenerate, additional constants of the motion enter the play. But although it is the Weyl transform of the state operator, the Wigner function is not necessarily a function of the Weyl...... transforms of the constants of the motion. We derive conditions for which this is actually the case. The Wigner functions of the energy eigenstates of a two-dimensional isotropic harmonic oscillator serve as an important illustration....
Bonilla, L. L.; Carretero, M.; Segura, A.
2017-12-01
When quantized, traces of classically chaotic single-particle systems include eigenvalue statistics and scars in eigenfuntions. Since 2001, many theoretical and experimental works have argued that classically chaotic single-electron dynamics influences and controls collective electron transport. For transport in semiconductor superlattices under tilted magnetic and electric fields, these theories rely on a reduction to a one-dimensional self-consistent drift model. A two-dimensional theory based on self-consistent Boltzmann transport does not support that single-electron chaos influences collective transport. This theory agrees with existing experimental evidence of current self-oscillations, predicts spontaneous collective chaos via a period doubling scenario, and could be tested unambiguously by measuring the electric potential inside the superlattice under a tilted magnetic field.
Kilpatrick, Zachary P.
2009-10-29
We study the spatiotemporal dynamics of a two-dimensional excitatory neuronal network with synaptic depression. Coupling between populations of neurons is taken to be nonlocal, while depression is taken to be local and presynaptic. We show that the network supports a wide range of spatially structured oscillations, which are suggestive of phenomena seen in cortical slice experiments and in vivo. The particular form of the oscillations depends on initial conditions and the level of background noise. Given an initial, spatially localized stimulus, activity evolves to a spatially localized oscillating core that periodically emits target waves. Low levels of noise can spontaneously generate several pockets of oscillatory activity that interact via their target patterns. Periodic activity in space can also organize into spiral waves, provided that there is some source of rotational symmetry breaking due to external stimuli or noise. In the high gain limit, no oscillatory behavior exists, but a transient stimulus can lead to a single, outward propagating target wave. © Springer Science + Business Media, LLC 2009.
Round Ligament Varicosities During Pregnancy: Case Report
Energy Technology Data Exchange (ETDEWEB)
Baek, Chang Kyu; Oh, Young Taik; Jung, Dae Chul [Yonsei University Health System, Seoul (Korea, Republic of)
2011-12-15
There are various causes of a painful palpable mass in the groin during pregnancy. The differential diagnoses of an inguinal mass include hernia, lymphadenopathy, mesothelial cyst, cystic lymphangioma, neoplasms (lipoma, leiomyoma and sarcoma), endometriosis, embryonic remnants and round ligament varicosities. Among them, round ligament varicosities can be easily misdiagnosed as an inguinal hernia in a pregnant woman. These lesions should be managed conservatively because they resolve spontaneously during the postpartum period. Ultrasonography can help make the diagnosis of round ligament varicosities and so prevent unnecessary surgical intervention and the associated morbidity. Herein we report on a case of round ligament varicosities that presented during pregnancy and this condition was readily diagnosed via Doppler sonography
On harmonic oscillators on the two-dimensional sphere S2 and the hyperbolic plane H2
International Nuclear Information System (INIS)
Ranada, Manuel F.; Santander, Mariano
2002-01-01
Two Harmonic Oscillators (isotropic and nonisotropic 2:1) are studied on the two-dimensional sphere S 2 and the hyperbolic plane H 2 . Both systems are integrable and super-integrable with constants of motion quadratic in the momenta. These properties are shown to derive from a complex factorization for the constants of motion, which holds for arbitrary values of the curvature κ, and the dynamics of the Euclidean harmonic 1:1 and 2:1 oscillators is directly recovered for κ=0. The harmonic oscillators on either the standard unit sphere (radius R=1) or the unit Lobachewski plane ('radius' R=1) appear as the particular values of the κ-dependent potentials for the values κ=1 and κ=-1. Finally a particular potential is proposed for representing the general spherical (hyperbolic) n:1 anisotropic harmonic oscillator on a two-dimensional manifold of constant curvature
Varicose Vein And Ecchymosis: A Case Report
Directory of Open Access Journals (Sweden)
Ertan Yetkin
2017-08-01
Full Text Available Assessment of varicose vein and chronic venous insufficiency and making a differential diagnosis in patients suffering from a variety of sign and symptoms is sometimes a big challenge in daily clinical practice. Here, we present a female patient with varicose vein symptoms and ecchymosis on her lower extremities. Several irregular shaped ecchymotic lesions on both extremities in different stage of healing with deep purple have been treated by using micronized purified flavonoid fraction.
Varicose Vein And Ecchymosis: A Case Report
Ertan Yetkin; Selçuk Öztürk; Mehmet ILeri
2017-01-01
Assessment of varicose vein and chronic venous insufficiency and making a differential diagnosis in patients suffering from a variety of sign and symptoms is sometimes a big challenge in daily clinical practice. Here, we present a female patient with varicose vein symptoms and ecchymosis on her lower extremities. Several irregular shaped ecchymotic lesions on both extremities in different stage of healing with deep purple have been treated by using micronized purified flavonoid fraction.
Directory of Open Access Journals (Sweden)
Kwang-Je Kim
2007-08-01
Full Text Available A Smith-Purcell device can operate as a backward-wave oscillator for intense, narrow-bandwidth, continuous wave radiation at terahertz wavelengths. We determine the requirements on electron beam current and emittance for the system to oscillate based on a three-dimensional extension of our previous two-dimensional analysis. It is found that specially designed electron beams are required with a current that exceeds a certain threshold value and a flat transverse profile that allows the beam to travel very close to the grating surface. Two methods for producing electron beams with the required characteristics are discussed.
Three-dimensional free electron laser dispersion relation including betatron oscillations
International Nuclear Information System (INIS)
Chin, Y.H.; Kim, K.J.; Xie, M.
1991-08-01
We have developed a 3-D FEL theory based upon the Maxwell-Vlasov equations including the effects of the energy spread and emittance of the electron beam, and of betatron oscillations. The radiation field is expressed in terms of the Green's function of the inhomogeneous wave equation and the distribution function of the electron beam. The distribution function is expanded in terms of a set of orthogonal functions determined by the unperturbed particle distribution. The coupled Maxwell-Vlasov equations are then reduced to a matrix equation, from which a dispersion relation for the eigenvalues is derived. In the limit of small betatron oscillation frequency, the present dispersion relation reduces to the well-known cubic equation of the one-dimensional theory in the limit of large beam size, and it gives the correct gain in the limit of small beam size. Comparisons of our numerical results with other approaches show good agreement. We present a handy empirical formula for the FEL gain of a 3-D Gaussian beam, as a function of the scaled parameters, that can be used for a quick estimate of the grain. 5 refs., 2 figs
Gerhardts, Rolf R.
2015-11-01
Model calculations for commensurability oscillations of the low-field magnetoresistance of two-dimensional electron systems (2DES) in lateral superlattices, consisting of unit cells with an internal structure, are compared with recent experiments. The relevant harmonics of the effective modulation potential depend not only on the geometrical structure of the modulated unit cell, but also strongly on the nature of the modulation. While higher harmonics of an electrostatically generated surface modulation are exponentially damped at the position of the 2DES about 90 nm below the surface, no such damping appears for strain-induced modulation generated, e.g., by the deposition of stripes of calixarene resist on the surface before cooling down the sample.
One-dimensional modelling of limit-cycle oscillation and H-mode power scaling
DEFF Research Database (Denmark)
Wu, Xingquan; Xu, Guosheng; Wan, Baonian
2015-01-01
To understand the connection between the dynamics of microscopic turbulence and the macroscale power scaling in the L-I-H transition in magnetically confined plasmas, a new time-dependent, one-dimensional (in radius) model has been developed. The model investigates the radial force balance equation...... at the edge region of the plasma and applies the quenching effect of turbulence via the E x B flow shear rate exceeding the shear suppression threshold. By slightly ramping up the heating power, the spatio-temporal evolution of turbulence intensity, density and pressure profiles, poloidal flow and E x B flow...... and the turbulence intensity depending on which oscillation of the diamagnetic flow or poloidal flow is dominant. Specifically, by including the effects of boundary conditions of density and temperature, the model results in a linear dependence of the H-mode access power on the density and magnetic field...
Assessment and management of patients with varicose veins.
Allen, Louise
Varicose veins are enlarged superficial veins found in the legs. This article explores the anatomy and physiology of the venous system to assist nurses to assess, manage and treat patients with varicose veins.
Kozlov, I. V.; Kolesnichenko, Yu. A.
2017-07-01
We present a theoretical study of the spatial distribution of the local density of states (LDOS) and the local magnetization density (LMD) in the vicinity of a magnetic point-defect in a degenerate two-dimensional electron gas with a mixed Rashba-Dresselhaus spin-orbit coupling interaction (SOI). The dependence of the Friedel oscillations, which arise under these conditions, on the ratio of the SOI constants is investigated. We obtain asymptotic expressions for the oscillatory parts of the LDOS and the LMD, that are accurate for large distances from the defect. It is shown, that the Friedel oscillations are significantly anisotropic and contain several harmonics for certain ratios of the SOI constants. Period of the oscillations for directions along the symmetry axes of the Fermi contours are determined. Finally, we introduce a method for determining the values of the two SOI constants by measuring the period of the Friedel oscillations of the LDOS and the LMD for different harmonics.
International Nuclear Information System (INIS)
Lasker, L.
1976-01-01
OSCIL is a program to predict the effects of seismic input on a HTGR core. The present model is a one-dimensional array of blocks with appropriate spring constants, inter-elemental and ground damping, and clearances. It can be used more generally for systems of moving masses separated by nonlinear springs and dampers
Energy Technology Data Exchange (ETDEWEB)
Lasker, L. (ed.)
1976-01-01
OSCIL is a program to predict the effects of seismic input on a HTGR core. The present model is a one-dimensional array of blocks with appropriate spring constants, inter-elemental and ground damping, and clearances. It can be used more generally for systems of moving masses separated by nonlinear springs and dampers.
An efficient method for simulation of noisy coupled multi-dimensional oscillators
Stinchcombe, Adam R.; Forger, Daniel B.
2016-09-01
We present an efficient computational method for the study of populations of noisy coupled oscillators. By taking a population density approach in which the probability density of observing an oscillator at a point of state space is the primary variable instead of the states of all of the oscillators, we are able to seamlessly account for intrinsic noise within the oscillators and global coupling within the population. The population is assumed to consist of a large number of oscillators so that the noise process is well sampled over the population. Our numerical method is able to solve the governing equation even in the challenging case of limit cycle oscillators with a large number of state variables. Instead of simulating a prohibitive number of oscillators, our particle method simulates relatively few particles allowing for the efficient solution of the governing equation.
Mammographic varicosities indicative of a superior mediastinal ...
African Journals Online (AJOL)
In addition, an abnormal calibre of the superficial veins can reflect not only underrying breast pathology, but a collateral venous return resulting from an upper mediastinal obstruction. A case mammographically demonstrating mammary varicosities resulting from a superior mediastinal syndrome is described. S. Afr. Med.
Directory of Open Access Journals (Sweden)
N. S. Ginzburg
2015-12-01
Full Text Available A coaxial Ka-band backward wave oscillator with a two-dimensional Bragg structure located at the output of the interaction space has been studied. This structure has a double-period corrugation and provides azimuthal electromagnetic energy fluxes, which act on the synchronized radiation of an oversized tubular electron beam. Proof-of-principle experiments were conducted based on the Saturn thermionic accelerator (300 keV/200 A/2 μs. In accordance with simulations, narrow-band generation was obtained at a frequency of 30 GHz and a power level of 1.5–2 MW. As a result, the possibility of using a two-dimensional distributed feedback mechanism in oscillators of the Cherenkov type has been demonstrated.
Coexistence of Two- and Three-dimensional Shubnikov-de Haas Oscillations in Ar^+ -irradiated KTaO_3
Energy Technology Data Exchange (ETDEWEB)
Harashima, S.; Bell, C.; Kim, M.; Yajima, T.; Hikita, Y.; Hwang, H.Y.
2012-05-16
We report the electron doping in the surface vicinity of KTaO{sub 3} by inducing oxygen-vacancies via Ar{sup +}-irradiation. The doped electrons have high mobility (> 10{sup 4} cm{sup 2}/Vs) at low temperatures, and exhibit Shubnikov-de Haas oscillations with both two- and three-dimensional components. A disparity of the extracted in-plane effective mass, compared to the bulk values, suggests mixing of the orbital characters. Our observations demonstrate that Ar{sup +}-irradiation serves as a flexible tool to study low dimensional quantum transport in 5d semiconducting oxides.
Varicose Veins: Role of Mechanotransduction of Venous Hypertension
Atta, Hussein M.
2012-01-01
Varicose veins affect approximately one-third of the adult population and result in significant psychological, physical, and financial burden. Nevertheless, the molecular pathogenesis of varicose vein formation remains unidentified. Venous hypertension exerted on veins of the lower extremity is considered the principal factor in varicose vein formation. The role of mechanotransduction of the high venous pressure in the pathogenesis of varicose vein formation has not been adequately investigated despite a good progress in understanding the mechanomolecular mechanisms involved in transduction of high blood pressure in the arterial wall. Understanding the nature of the mechanical forces, the mechanosensors and mechanotransducers in the vein wall, and the downstream signaling pathways will provide new molecular targets for the prevention and treatment of varicose veins. This paper summarized the current understanding of mechano-molecular pathways involved in transduction of hemodynamic forces induced by blood pressure and tries to relate this information to setting of venous hypertension in varicose veins. PMID:22489273
Directory of Open Access Journals (Sweden)
Rosario Dell’Aquila
Full Text Available The soil aggregate stability is determined generally by sifting the soil samples in water using a sieve-shaker (wet sieving. The Author has developed an original model of automatic sieve-shaker using a vertical oscillation system to the aim of an its possible use to determine the soil aggregate stability and dimensional distribution. The purpose of this note is to describe the construction and performance of the prototype currently used in the Laboratory for the Soil Structure Study of the ISAFOM – CNR. The proposed sieve-shaker, with the introduction of some innovations (protected by Italy Patent 0001332102, realizes the submersion and levelling of the soil samples using a lifter to support the containers with the water. With 6 workplaces it allows to process simultaneously up to 6 soil samples according to different test cycles. By means of the control panel it is possible to set up various determinations with the stroke of 3 cm and the oscillation frequency from 4 up to 80 oscillations per minute. The performance of the proposed sieve-shaker was verified with a technical test to verify the performance of the 6 workplaces to oscillation speed increasing up to 60 oscillations per minute and an agronomic test. The results have been submitted to analysis of variance considering the plots of the field from which have been taken the samples for repetitions and the six workplaces of the proposed sieve-shaker for experimental theses. The differences between the various workplaces have not been significant. This demonstrates that the behavior of the various workplaces is uniform. The dispersion in water at constant shaking time and increasing oscillation speed has evidenced a very significant inverse relation between the index of aggregate stability in water (IASW and number of oscillations per minute. This result demonstrates a constant performance of the proposed sieve-shaker to varying of the oscillation speed. The agnonomic test has demonstrated
Exact diagonalization of the D-dimensional spatially confined quantum harmonic oscillator
Directory of Open Access Journals (Sweden)
Kunle Adegoke
2016-01-01
Full Text Available In the existing literature various numerical techniques have been developed to quantize the confined harmonic oscillator in higher dimensions. In obtaining the energy eigenvalues, such methods often involve indirect approaches such as searching for the roots of hypergeometric functions or numerically solving a differential equation. In this paper, however, we derive an explicit matrix representation for the Hamiltonian of a confined quantum harmonic oscillator in higher dimensions, thus facilitating direct diagonalization.
Quantum oscillations in one-dimensional metal rings: Average over disorder
International Nuclear Information System (INIS)
Li, Q.; Soukoulis, C.M.
1986-01-01
We study the Aharonov-Bohm effect in single normal-metal rings and show that averaging the transmission coefficient T over disorder gives oscillations with a period of a half-flux quantum. As the elastic scattering gets stronger, the periodicity of oscillation of the conductance, which is related to T, gradually changes to a full-flux quantum, in agreement with recent experiments
Ortiz, L.; Varona, S.; Viyuela, O.; Martin-Delgado, M. A.
2018-02-01
We study the localization and oscillation properties of the Majorana fermions that arise in a two-dimensional electron gas (2DEG) with spin-orbit coupling (SOC) and a Zeeman field coupled with a d -wave superconductor. Despite the angular dependence of the d -wave pairing, localization and oscillation properties are found to be similar to the ones seen in conventional s -wave superconductors. In addition, we study a microscopic lattice version of the previous system that can be characterized by a topological invariant. We derive its real space representation that involves nearest and next-to-nearest-neighbors pairing. Finally, we show that the emerging chiral Majorana fermions are indeed robust against static disorder. This analysis has potential applications to quantum simulations and experiments in high-Tc superconductors.
Leach, P. G. L.; Nucci, M. C.
2004-09-01
The classical MICZ-Kepler problem is shown to be reducible to an isotropic two-dimensional system of linear harmonic oscillators and a conservation law in terms of new variables related to the Ermanno-Bernoulli constants and the components of the Poincaré vector. An algorithmic route to linearization is shown based on Lie symmetry analysis and the reduction method [ Nucci, J. Math. Phys. 37, 1772 (1996) ]. First integrals are also obtained by symmetry analysis and the reduction method [ Marcelli and Nucci,J. Math. Phys. 44, 2111 (2002) ].
Characterization of a porcine model of chronic superficial varicose veins.
Jones, Gregory T; Grant, Mark W; Thomson, Ian A; Hill, B Geraldine; van Rij, André M
2009-06-01
Previous animal models of venous disease, while inducing venous hypertension and valvular insufficiency, do not produce superficial varicose veins. In this study, we aimed to develop and characterize a pig-based model of superficial varicose veins. Right femoral arteriovenous fistulae (AVF) were surgically fashioned in young adult pigs. Animals were examined at postoperative times up to 15 weeks to determine the development of varicose veins and measurement of both blood pressure and flow velocities within the superficial thigh veins. Histology and vascular corrosion casts were used to characterize the resulting structural venous alterations. Porcine pathophysiological features were compared with those of human primary superficial varicose veins. Gross superficial varicosities developed over the ipsilateral medial thigh region after an initial lag period of 1-2 weeks. Veins demonstrated retrograde filling with valvular incompetence, and a moderate, non-pulsatile, venous hypertension, which was altered by changes in posture and Valsalva. Venous blood flow velocities were elevated to 15-30 cm/s in varicose veins. Structurally, pig varicose veins were enlarged, tortuous, had valvular degeneration, and regions of focal medial atrophy with or without overlying intimal thickening. The superficial varicose veins, which developed within this model, have a pathophysiology that is consistent with that observed in humans. The porcine femoral AVF model is proposed as a suitable experimental model to evaluate the pathobiology of superficial venous disease. It may also be suitable for the evaluation of treatment interventions including drug therapy.
Shchesnovich, Valery S; Desyatnikov, Anton S; Kivshar, Yuri S
2008-09-01
We study, analytically and numerically, the dynamics of interband transitions in two-dimensional hexagonal periodic photonic lattices. We develop an analytical approach employing the Bragg resonances of different types and derive the effective multi-level models of the Landau-Zener-Majorana type. For two-dimensional periodic potentials without a tilt, we demonstrate the possibility of the Rabi oscillations between the resonant Fourier amplitudes. In a biased lattice, i.e., for a two-dimensional periodic potential with an additional linear tilt, we identify three basic types of the interband transitions or Zener tunnelling. First, this is a quasi-one-dimensional tunnelling that involves only two Bloch bands and occurs when the Bloch index crosses the Bragg planes away from one of the high-symmetry points. In contrast, at the high-symmetry points (i.e., at the M and Gamma points), the Zener tunnelling is essentially two-dimensional, and it involves either three or six Bloch bands being described by the corresponding multi-level Landau-Zener-Majorana systems. We verify our analytical results by numerical simulations and observe an excellent agreement. Finally, we show that phase dislocations, or optical vortices, can tunnel between the spectral bands preserving their topological charge. Our theory describes the propagation of light beams in fabricated or optically-induced two-dimensional photonic lattices, but it can also be applied to the physics of cold atoms and Bose-Einstein condensates tunnelling in tilted two-dimensional optical potentials and other types of resonant wave propagation in periodic media.
Stochastic dynamics in a two-dimensional oscillator near a saddle-node bifurcation
Inchiosa, M. E.; in, V.; Bulsara, A. R.; Wiesenfeld, K.; Heath, T.; Choi, M. H.
2001-06-01
We study the oscillator equations describing a particular class of nonlinear amplifier, exemplified in this work by a two-junction superconducting quantum interference device. This class of dynamic system is described by a potential energy function that can admit minima (corresponding to stable solutions of the dynamic equations), or ``running states'' wherein the system is biased so that the potential minima disappear and the solutions display spontaneous oscillations. Just beyond the onset of the spontaneous oscillations, the system is known to show significantly enhanced sensitivity to very weak magnetic signals. The global phase space structure allows us to apply a center manifold technique to approximate analytically the oscillatory behavior just past the (saddle-node) bifurcation and compute the oscillation period, which obeys standard scaling laws. In this regime, the dynamics can be represented by an ``integrate-fire'' model drawn from the computational neuroscience repertoire; in fact, we obtain an ``interspike interval'' probability density function and an associated power spectral density (computed via Renewal theory) that agree very well with the results obtained via numerical simulations. Notably, driving the system with one or more time sinusoids produces a noise-lowering injection locking effect and/or heterodyning.
Three-Dimensional Dirac Oscillator with Minimal Length: Novel Phenomena for Quantized Energy
Directory of Open Access Journals (Sweden)
Malika Betrouche
2013-01-01
Full Text Available We study quantum features of the Dirac oscillator under the condition that the position and the momentum operators obey generalized commutationrelations that lead to the appearance of minimal length with the order of the Planck length, ∆xmin=ℏ3β+β′, where β and β′ are two positive small parameters. Wave functions of the system and the corresponding energy spectrum are derived rigorously. The presence of the minimal length accompanies a quadratic dependence of the energy spectrum on quantum number n, implying the property of hard confinement of the system. It is shown that the infinite degeneracy of energy levels appearing in the usual Dirac oscillator is vanished by the presence of the minimal length so long as β≠0. Not only in the nonrelativistic limit but also in the limit of the standard case (β=β′=0, our results reduce to well known usual ones.
Collective oscillations of strongly correlated one-dimensional bosons on a lattice.
Rigol, M; Rousseau, V; Scalettar, R T; Singh, R R P
2005-09-09
We study the dipole oscillations of strongly correlated 1D bosons, in the hard-core limit, on a lattice, by an exact numerical approach. We show that far from the regime where a Mott insulator appears in the system, damping is always present and increases for larger initial displacements of the trap, causing dramatic changes in the momentum distribution, n(k). When a Mott insulator sets in the middle of the trap, the center of mass barely moves after an initial displacement, and n(k) remains very similar to the one in the ground state. We also study changes introduced by the damping in the natural orbital occupations, and the revival of the center-of-mass oscillations after long times.
Phase-matching-free parametric oscillators based on two dimensional semiconductors
Ciattoni, A.; Marini, A.; Rizza, C.; Conti, C.
2017-01-01
Optical parametric oscillators are widely-used pulsed and continuous-wave tunable sources for innumerable applications, as in quantum technologies, imaging and biophysics. A key drawback is material dispersion imposing the phase-matching condition that generally entails a complex setup design, thus hindering tunability and miniaturization. Here we show that the burden of phase-matching is surprisingly absent in parametric micro-resonators adopting monolayer transition-metal dichalcogenides as...
International Nuclear Information System (INIS)
Cari, C; Suparmi, A
2013-01-01
The energy eigenvalues and eigenfunctions of Schrodinger equation for three dimensional harmonic oscillator potential plus Rosen-Morse non-central potential are investigated using NU method and Romanovski polynomial. The bound state energy eigenvalues are given in a closed form and corresponding radial wave functions are expressed in associated Laguerre polynomials while angular eigen functions are given in terms of Romanovski polynomials. The Rosen-Morse potential is considered to be a perturbation factor to the three dimensional harmonic oscillator potential that causes the increase of radial wave function amplitude and decrease of angular momentum length. Keywords: Schrodinger Equation, Three dimensional Harmonic Oscillator potential, Rosen-morse non-central potential, NU method, Romanovski Polynomials
Sakaguchi, Hidetsugu; Malomed, Boris A.
2017-10-01
We analyze the possibility of macroscopic quantum effects in the form of coupled structural oscillations and shuttle motion of bright two-component spin-orbit-coupled striped (one-dimensional, 1D) and semivortex (two-dimensional, 2D) matter-wave solitons, under the action of linear mixing (Rabi coupling) between the components. In 1D, the intrinsic oscillations manifest themselves as flippings between spatially even and odd components of striped solitons, while in 2D the system features periodic transitions between zero-vorticity and vortical components of semivortex solitons. The consideration is performed by means of a combination of analytical and numerical methods.
Thin three-dimensional droplets on an oscillating substrate with contact angle hysteresis
Bradshaw, J.; Billingham, J.
2016-01-01
Recent experiments [P. Brunet, J. Eggers, and R. D. Deegan, Phys. Rev. Lett. 99, 144501 (2007), 10.1103/PhysRevLett.99.144501] have shown that a liquid droplet on an inclined plane can be made to move uphill by sufficiently strong, vertical oscillations. In order to investigate this counterintuitive phenomenon we use a model in which liquid inertia and viscosity are assumed negligible so that the motion of the droplet is dominated by the applied acceleration due to the oscillation of the plate, gravity, and surface tension. We explain how the leading order motion of the droplet can be separated into a spreading mode and a swaying mode. For a linear contact line law, the maximum rise velocity occurs when these modes are in phase. We show that, both with and without contact angle hysteresis, the droplet can climb uphill and also that, for certain contact line laws, the motion of the droplet can produce footprints similar to experimental results. We show that if the two modes are out of phase when there is no contact angle hysteresis, the inclusion of hysteresis can force them into phase. This in turn increases the rise velocity of the droplet and can, in some cases, cause a sliding droplet to climb.
Botari, Tiago; Leonel, Edson D
2013-01-01
A modification of the one-dimensional Fermi accelerator model is considered in this work. The dynamics of a classical particle of mass m, confined to bounce elastically between two rigid walls where one is described by a nonlinear van der Pol type oscillator while the other one is fixed, working as a reinjection mechanism of the particle for a next collision, is carefully made by the use of a two-dimensional nonlinear mapping. Two cases are considered: (i) the situation where the particle has mass negligible as compared to the mass of the moving wall and does not affect the motion of it; and (ii) the case where collisions of the particle do affect the movement of the moving wall. For case (i) the phase space is of mixed type leading us to observe a scaling of the average velocity as a function of the parameter (χ) controlling the nonlinearity of the moving wall. For large χ, a diffusion on the velocity is observed leading to the conclusion that Fermi acceleration is taking place. On the other hand, for case (ii), the motion of the moving wall is affected by collisions with the particle. However, due to the properties of the van der Pol oscillator, the moving wall relaxes again to a limit cycle. Such kind of motion absorbs part of the energy of the particle leading to a suppression of the unlimited energy gain as observed in case (i). The phase space shows a set of attractors of different periods whose basin of attraction has a complicated organization.
Control of Limit Cycle Oscillations of a Two-Dimensional Aeroelastic System
Directory of Open Access Journals (Sweden)
M. Ghommem
2010-01-01
Full Text Available Linear and nonlinear static feedback controls are implemented on a nonlinear aeroelastic system that consists of a rigid airfoil supported by nonlinear springs in the pitch and plunge directions and subjected to nonlinear aerodynamic loads. The normal form is used to investigate the Hopf bifurcation that occurs as the freestream velocity is increased and to analytically predict the amplitude and frequency of the ensuing limit cycle oscillations (LCO. It is shown that linear control can be used to delay the flutter onset and reduce the LCO amplitude. Yet, its required gains remain a function of the speed. On the other hand, nonlinear control can be effciently implemented to convert any subcritical Hopf bifurcation into a supercritical one and to significantly reduce the LCO amplitude.
Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev; Rasmussen, Morten Fischer; Jensen, Jørgen Arendt
2014-10-01
The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flow-rig system. Measurements of the synthesized transverse oscillating fields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial, transverse, and elevation velocity components simultaneously. Data are acquired using a research ultrasound scanner. The velocity measurements are conducted with steady flow in sixteen different directions. For a specific flow direction with [α, ß] = [45, 15]°, the mean estimated velocity vector at the center of the vessel is (v(x), v(y), v(z)) = (33.8, 34.5, 15.2) ± (4.6, 5.0, 0.6) cm/s where the expected velocity is (34.2, 34.2, 13.0) cm/s. The velocity magnitude is 50.6 ± 5.2 cm/s with a bias of 0.7 cm/s. The flow angles α and ß are estimated as 45.6 ± 4.9° and 17.6 ± 1.0°. Subsequently, the precision and accuracy are calculated over the entire velocity profiles. On average for all direction, the relative mean bias of the velocity magnitude is -0.08%. For α and ß, the mean bias is -0.2° and -1.5°. The relative standard deviations of the velocity magnitude ranges from 8 to 16%. For the flow angles, the ranges of the mean angular deviations are 5° to 16° and 0.7° and 8°.
Sclerotherapy and foam sclerotherapy for varicose veins.
Coleridge Smith, P
2009-12-01
To review published evidence concerning treatment of varicose veins using ultrasound-guided foam sclerotherapy (UGFS) to assess the safety and efficacy of this treatment. Medical literature databases including MedLine, Embase and DH-DATA were searched for recent literature concerning UGFS. Papers describing the early results and later outcome have been assessed and their main findings were included in this summary. Few randomized studies have been published in this field and much of the available data come from clinical series reported by individual clinicians. It is clear that foam sclerotherapy is far more effective than liquid sclerotherapy and that ultrasound imaging allows the treatment to be delivered accurately to affected veins. There is evidence that 3% polidocanol foam is no more effective than 1% polidocanol foam. The optimum ratio of gas to liquid is 4:1, although a range of ratios is reported in the published work. There is a wide variation in the volume used as well as the method by which it is injected. The use of carbon dioxide foam reduces the systemic complications, particularly visual disturbance, as compared with air foams. Very few serious adverse events have been reported in the literature despite the widespread use of this method. Rates of recanalization of saphenous trunks following UGFS are similar to those observed after endovenous laser and endovenous RF ablation of veins, as well as the residual incompetence after surgical treatment. UGFS is a safe and effective method of treating varicose veins. The relative advantages or disadvantages of this treatment in the longer term have yet to be published.
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Stuart, Matthias Bo; Tomov, Borislav Gueorguiev
2014-01-01
The 3-D transverse oscillation method is investigated by estimating 3-D velocities in an experimental flowrigsystem. Measurements of the synthesized transverse oscillatingfields are presented as well. The method employs a 2-D transducer; decouples the velocity estimation; and estimates the axial......, transverse, and elevation velocity components simultaneously. Data are acquired using a research ultrasound scanner. The velocity measurements are conducted with steady flow in sixteen different directions. For a specific flow direction with [α,β]= [45,15]°, the mean estimated velocity vector at the center...... of the vessel is (vx,vy,vz) = (33.8,34.5,15.2) ± (4.6,5.0,0.6)cm/s where the expected velocity is (34.2,34.2,13.0)cm/s. The velocity magnitude is 50.6 ± 5.2cm/s with a bias of 0.7cm/s.The flow angles α and β are estimated as 45.6 ± 4.9° and 17.6± 1.0°. Subsequently, the precision and accuracy are calculated...
Aharonov-Bohm oscillations in a one-dimensional Wigner crystal ring
Energy Technology Data Exchange (ETDEWEB)
Krive, I.V. [Department of Applied Physics, Chalmers University of Technology Goeteborg University, S-412 96 Goeteborg (Sweden)]|[B. I. Verbin Institute for Low Temperature Physics and Engineering, 47 Lenin Avenue, 310164 Kharkov (Ukraine); Sandstroem, P.; Shekhter, R.I. [Department of Applied Physics, Chalmers University of Technology Goeteborg University, S-412 96 Goeteborg (Sweden); Girvin, S.M. [Department of Physics, Indiana University, Bloomington, Indiana 47405 (United States); Jonson, M. [Department of Applied Physics, Chalmers University of Technology Goeteborg University, S-412 96 Goeteborg (Sweden)
1995-12-15
({ital V}{sub {ital p}} is the amplitude of the pinning potential, {ital T}{sub 0}={h_bar}{ital v}{sub {ital F}}/{ital L}, {ital v}{sub {ital F}}{similar_to}{h_bar}/{ital ma} is the drift velocity of a Wigner crystal ring with lattice spacing {ital a}). For very weak pinning, {ital V}{sub {ital p}}{much_lt}{ital T}{sub 0}, the influence of the barrier on the persistent current of a Wigner crystal ring is negligibly small. We have also shown that unscreened, long-range Coulomb interactions increase the stiffness of the Wigner lattice. This leads to additional suppression of the amplitude of Aharonov-Bohm oscillations, but makes the predicted anomalous temperature dependence of the persistent current in the strong pinning limit even more pronounced. The corresponding temperature of the peak will also be shifted by a factor which depends on the number of particles in the ring. The impact of dissipation on the persistent current of a Wigner crystal ring is also studied.
Endovascular Radiofrequency Ablation for Varicose Veins
2011-01-01
Executive Summary Objective The objective of the MAS evidence review was to conduct a systematic review of the available evidence on the safety, effectiveness, durability and cost–effectiveness of endovascular radiofrequency ablation (RFA) for the treatment of primary symptomatic varicose veins. Background The Ontario Health Technology Advisory Committee (OHTAC) met on August 26th, 2010 to review the safety, effectiveness, durability, and cost-effectiveness of RFA for the treatment of primary symptomatic varicose veins based on an evidence-based review by the Medical Advisory Secretariat (MAS). Clinical Condition Varicose veins (VV) are tortuous, twisted, or elongated veins. This can be due to existing (inherited) valve dysfunction or decreased vein elasticity (primary venous reflux) or valve damage from prior thrombotic events (secondary venous reflux). The end result is pooling of blood in the veins, increased venous pressure and subsequent vein enlargement. As a result of high venous pressure, branch vessels balloon out leading to varicosities (varicose veins). Symptoms typically affect the lower extremities and include (but are not limited to): aching, swelling, throbbing, night cramps, restless legs, leg fatigue, itching and burning. Left untreated, venous reflux tends to be progressive, often leading to chronic venous insufficiency (CVI). A number of complications are associated with untreated venous reflux: including superficial thrombophlebitis as well as variceal rupture and haemorrhage. CVI often results in chronic skin changes referred to as stasis dermatitis. Stasis dermatitis is comprised of a spectrum of cutaneous abnormalities including edema, hyperpigmentation, eczema, lipodermatosclerosis and stasis ulceration. Ulceration represents the disease end point for severe CVI. CVI is associated with a reduced quality of life particularly in relation to pain, physical function and mobility. In severe cases, VV with ulcers, QOL has been rated to be as bad
International Nuclear Information System (INIS)
Rusinek, I.
1980-01-01
A semiclassical procedure previously used for collinear CID calculations is applied to the perpendicular collisions (2D, no rotation, zero impact parameter) of a Morse homonuclear diatomic molecule and an atom, interacting via an exponential repulsive potential. Values of the dissociation probability (P/sup diss/) are given as a function of total energy (E/sub t/) and initial vibrational state (n 1 =0,1,3,5) for a system with three identical masses. The results are compared with the P/sup diss/ previously reported for an identical one dimensional system. We find: (a) quasiclassical P/sup diss/ that are a good approximation to the semiclassical ones, if CID is classically allowed, (b) vibrational enhancement of CID, and (c) energetic thresholds for dissociation similar to the ones found in the collinear case
Best practice for assessment of patients with varicose veins.
Horrocks, Emma; Roake, Justin; Lewis, David
2008-05-23
Varicose veins are a significant health problem which attract much medicolegal attention. Recent publications have suggested "best practice" regarding assessment of patients with varicose veins. A retrospective audit was performed comparing clinical practice in a New Zealand teaching hospital with suggested standards. Clinic letters from 80 patients awaiting varicose vein surgery were reviewed. Data were collated regarding presenting problem, relevant medical history, clinical findings on examination, further investigations, and outcome. Presenting complaint was noted for 99% of patients but actual symptoms were only recorded for 41%. The degree of disability caused by varicose veins was documented for 33% and patient concerns in 4%. Half of the patients presented with leg ulcers but ankle-brachial indices (ABPIs) were only recorded in 26% of clinic letters. Duplex scanning was recommended prior to surgery for 69% of patients and hand held Doppler assessment of venous disease was recorded in 61% cases. Clinic letters did not specify the nature and extent of disease in 6% of cases, and although every patient was recommended for surgery, the exact procedure was specified in only 24%. Details of surgical risks and complications were only present in 20% of letters, and only 21% of patients received a printed information sheet. The quality of the data recorded in the clinic letters of fell below suggested standards for assessment of patients with varicose veins. Improving the documentation of patient assessment will allow better communication between providers of healthcare and make clinical errors less likely.
Suitability of Varicose Veins for Endovenous Treatments
International Nuclear Information System (INIS)
Goode, S. D.; Kuhan, G.; Altaf, N.; Simpson, R.; Beech, A.; Richards, T.; MacSweeney, S. T.; Braithwaite, B. D.
2009-01-01
The aim of the study was to assess the suitability of radiofrequency ablation (RFA), endovenous laser ablation (EVLA), and foam sclerotherapy (FS) for patients with symptomatic varicose veins (VVs). The study comprised 403 consecutive patients with symptomatic VVs. Data on 577 legs from 403 consecutive patients with symptomatic VVs were collected for the year 2006. Median patient age was 55 years (interquartile range 45-66), and 62% patients were women. A set of criteria based on duplex ultrasonography was used to select patients for each procedure. Great saphenous vein (GSV) reflux was present in 77% (446 of 577) of legs. Overall, 328 (73%) of the legs were suitable for at least one of the endovenous options. Of the 114 legs with recurrent GSV reflux disease, 83 (73%) were suitable to receive endovenous therapy. Patients with increasing age were less likely to be suitable for endovenous therapy (P = 0.03). Seventy-three percent of patients with VVs caused by GSV incompetence are suitable for endovenous therapy.
Energy Technology Data Exchange (ETDEWEB)
Kosevich, Y.A. (All-Union Surface and Vacuum Research Centre, 117334 Moscow, U.S.S.R. (SU)); Syrkin, E.S. (Institute for Low Temperature Physics and Engineering, UkrSSR Academy of Sciences, 310164 Kharkov (USSR))
1991-01-01
Low-frequency collective oscillations in a superlattice consisting of alternating highly anisotropic layers are considered. Such superstructure may be formed in the ferroelastic near the structural phase transition by alternation of twins. For the surface waves, propagating along the layers, the conditions and the range of existence of those with the dispersion law {omega}{similar to}{ital k}{sup 1/2}, characteristic for two-dimensional plasmons, have been analyzed for a solid-state system with consideration for elastic anisotropy and retardation of acoustic waves. Such excitations ( dyadons'') were used by Horovitz, Barsch, and Krumhansl (Phys. Rev. B 36, 8895 (1987)) in an attempt to explain the anomalies of low-temperature thermodynamic and kinetic characteristics of high-{ital T}{sub {ital c}} superconductors. We have shown that the similarity of the densities of the matching phases and the retardation of elastic waves in the crystal narrow the range of existence of dyadons, but the high elastic anisotropy of the solid phases enlarges the range of existence of such excitations in solid-state systems. An example of possible crystalline geometry of the phase matching, for which there arise collective excitations of the type under consideration, is found. For transverse and longitudinal waves propagating across the layers, the existence is proved of low-frequency acoustic branches separated by a wide gap from the nearest optical branches.
Kosevich, Yu. A.; Syrkin, E. S.
1991-01-01
Low-frequency collective oscillations in a superlattice consisting of alternating highly anisotropic layers are considered. Such superstructure may be formed in the ferroelastic near the structural phase transition by alternation of twins. For the surface waves, propagating along the layers, the conditions and the range of existence of those with the dispersion law ω~k1/2, characteristic for two-dimensional plasmons, have been analyzed for a solid-state system with consideration for elastic anisotropy and retardation of acoustic waves. Such excitations (``dyadons'') were used by Horovitz, Barsch, and Krumhansl [Phys. Rev. B 36, 8895 (1987)] in an attempt to explain the anomalies of low-temperature thermodynamic and kinetic characteristics of high-Tc superconductors. We have shown that the similarity of the densities of the matching phases and the retardation of elastic waves in the crystal narrow the range of existence of dyadons, but the high elastic anisotropy of the solid phases enlarges the range of existence of such excitations in solid-state systems. An example of possible crystalline geometry of the phase matching, for which there arise collective excitations of the type under consideration, is found. For transverse and longitudinal waves propagating across the layers, the existence is proved of low-frequency acoustic branches separated by a wide gap from the nearest optical branches.
Gilmore, K A; Bohnet, J G; Sawyer, B C; Britton, J W; Bollinger, J J
2017-06-30
We present a technique to measure the amplitude of a center-of-mass (c.m.) motion of a two-dimensional ion crystal of ∼100 ions. By sensing motion at frequencies far from the c.m. resonance frequency, we experimentally determine the technique's measurement imprecision. We resolve amplitudes as small as 50 pm, 40 times smaller than the c.m. mode zero-point fluctuations. The technique employs a spin-dependent, optical-dipole force to couple the mechanical oscillation to the electron spins of the trapped ions, enabling a measurement of one quadrature of the c.m. motion through a readout of the spin state. We demonstrate sensitivity limits set by spin projection noise and spin decoherence due to off-resonant light scattering. When performed on resonance with the c.m. mode frequency, the technique demonstrated here can enable the detection of extremely weak forces (limits and search for physics beyond the standard model.
Talic, Goran; Talic, Luka; Stevanovic-Papica, Djurdjica; Nozica-Radulovic, Tatjana; Novakovic-Bursac, Snjezana
2017-01-01
Introduction: Scoliosis is a complex three-dimensional spine deformity with the frontal plane deflexion (side-shift) of the series of vertebra from the midline and with torque deformity of vertebra, ribs, and the entire trunk towards the apex of curve. Chronic venous diseases present a group of pathological conditions caused by the increased venous pressure. The venous pressure may be increased due to genetics, ligament laxity, general obesity, injuries, and changes in biomechanics of spine and lower extremities, etc. Aim: The aim of the study is to evaluate the frequency of the varicose veins in women previously treated for the adolescent idiopathic scoliosis. Material and methods: In the period August 1, 2015 - December 30, 2015 the Team for scoliosis in the Institute for the Physical medicine and Rehabilitation „Dr Miroslav Zotović” in Banja Luka in study program has clinically assessed 89 women previously treated for the adolescent idiopathic scoliosis (AIS) and the control group of 87 women without history of scoliosis. Results: Results of the study led to conclusion that occurrence of the varicose veins was more frequent in the group of women who were treated for the AIS (23/89 or 25.8%) in comparison with control group with no history of AIS (7/87 or 8.1%). Conclusion: This might relate AIS with some other connective tissue disorder, like venous varices, for instance. PMID:28790540
The risk of varicose veins in standing female workers
Directory of Open Access Journals (Sweden)
Tony Hidayat
2013-07-01
Full Text Available AbstrakLatar belakang:Varises sering terjadi pada karyawan yang harus bekerja dalam posisi kerja berdiri. Tujuan penelitian ini untuk mengetahui beberapa faktor risiko terhadap varises tungkai dan atau kaki di antara pekerja perempuan. Metode:Penelitian potong lintang ini dilakukan pada Januari-Maret 2010. Sampel penelitian yang dipilih secara purposif yang memenuhi kriteria inklusi penelitian di antara pekerja perempuan perlu bekerja dalam posisi kerja berdiri. Data dikumpulkan dengan wawancara, pemeriksaan fisik dan observasi posisi kerja berdiri. Pengolahan data untuk menentukan faktor dominan terhadap varises menggunakan pendekatan risiko relatif.Hasil:Dari 152 karyawan yang terdapat 111 yang bersedia mengikuti penelitian, dan yang menderita varises tungkai dan atau kaki sebanyak 52,3% (53 orang. Sebagian besar responden berusia 18-35 tahun, memiliki masa kerja 3-17 tahun, bekerja dalam posisi kerja banyak berdiri. Sebagian kecil responden memiliki riwayat varises di dalam keluarga (13,51%, memakai kontrasepsi oral (11,71%, memiliki kebiasaan olah raga (18,02% dan memakai sepatu hak tinggi (11,71%. Faktor umur, pemakaian kontrasepsi oral, pemakaian sepatu hak tinggi, kebiasaan olah raga, posisi kerja berdiri, tempat kerja, dan masa kerja tidak berhubungan dengan varises tungkai dan atau kaki. Karyawan yang mempunyai dibandingkan dengan yang tidak mempunyai riwayat keluarga varises, berisiko 69% lebih tinggi menderita varises [risiko relatif (RR = 1,69; P = 0.121]. Kesimpulan:Karyawan yang mempunyai riwayat keluarga varises berisiko lebih tinggi menderita varises. (Health Science Indones 2013;1:47-50 Kata kunci:varises, posisi kerja berdiriAbstractBackground: Varicose veins often occur in employees who have to work in a position of standing work. The purpose of this study to determine risk factors for varicose veins and leg or foot among women workers.Methods: In this cross-sectional study in January-March 2010 the
Medical liability insurance claims after treatment of varicose veins
Dickhoff, C.; Cremers, J. E. L.; Legemate, D. A.; Koelemay, M. J. W.
2014-01-01
Since insight into the reason for filing claims after treatment of varicose veins of the lower extremity might help prevent future claims, we determined the incidence of and reasons for medical liability insurance claims after such treatments in the Netherlands. We performed a retrospective review
Foam treatment for varicose veins; efficacy and safety | Kotb ...
African Journals Online (AJOL)
Introduction: Lower extremity varicose vein is a common disease. Sclerotherapy can be used to treat truncal varices of the superficial venous system. This involves injecting a sclerosant intraluminally in order to cause fibrosis and eventual obliteration of the vein. Objective: To demonstrate the efficacy and safety of foam ...
Czech Academy of Sciences Publication Activity Database
Smrčka, Ludvík
2016-01-01
Roč. 77, Mar (2016), s. 108-113 ISSN 1386-9477 Institutional support: RVO:68378271 Keywords : lateral superlattices * commensurability oscillations * in-plane magnetic field Subject RIV: BE - Theoretical Physics Impact factor: 2.221, year: 2016
Energy Technology Data Exchange (ETDEWEB)
Qasrawi, A.F., E-mail: aqasrawi@atilim.edu.tr [Group of Physics, Faculty of Engineering, Atilim University, 06836 Ankara (Turkey); Department of Physics, Arab-American University, Jenin, West Bank, Palestine (Country Unknown); Gasanly, N.M. [Department of Physics, Middle East Technical University, 06800 Ankara (Turkey)
2013-08-15
Due to the importance of the TlInSe{sub 2} crystal as neutron and γ-ray detectors, its electrical and dispersive optical parameters have been investigated. Particularly, the anisotropic current conduction mechanism in the temperature region of 100–350 K and the room temperature anisotropic dispersive optical properties were studied by means of electrical conductivity and optical reflectance, respectively. It has been shown that the mixed conduction is the most dominant transport mechanism in the TlInSe{sub 2} crystals. Particularly, when the electric field is applied perpendicular to the crystal's c-axis, the main dominant current transport mechanism is due to the mixed conduction and the variable range hopping above and below 160 K, respectively. When the electric field is applied parallel to the crystal's c-axis, the electrical conductivity is dominated by the thermionic emission, mixed conduction and variable range hopping at high, moderate and low temperatures, respectively. The optical reflectivity analysis in the wavelength range 210–1500 nm revealed a clear anisotropy effect on the dispersive optical parameters. Particularly, the static refractive index, static dielectric constant, dispersion energy and oscillator energy exhibited values of 2.50, 6.24, 20.72 eV and 3.96 eV, and values of 3.05, 9.33, 39.27 eV and 4.72 eV for light propagation parallel and perpendicular to the crystal's c-axis, respectively. Moreover, the frequency dependence of the dielectric constant, ε(ω), reflected strong dielectric anisotropy that exhibit maximum ε(ω) value of 38.80 and 11.40 at frequencies of 11.07 × 10{sup 14} Hz for light propagation parallel and perpendicular to the crystal's c-axis, respectively. The anisotropy in the ε(ω) makes the TlInSe{sub 2} crystals attractive to be used as nonvolatile static memory devices. - Graphical abstract: Display Omitted - Highlights: • The anisotropic transport mechanism in low dimensional TlInSe{sub 2
Chang-Hua Zou; Kang Cheng
2009-01-01
Problem statement: Cardiovascular Diseases (CVD) continued to be the leading cause of death. Failure or abnormal cardiac cellular or sub-cellular vibrations (oscillations) could lead failure or abnormal heart beats that could cause CVD. Understanding the mechanisms of the vibrations (oscillations) could help to prevent or to treat the diseases. Scientists have studied the mechanisms for more than 100 years. To our knowledge, the mechanisms are still unclear today...
Hur, Min Young; Lee, Ho-Jun; Lee, Hae June; Choe, Won Ho; Seon, Jong Ho
2013-09-01
Oscillations of the plasma potential have been observed in many Hall thruster experiments. It was estimated that the oscillations are triggered by the interaction between the plasma and the dielectric materials such as secondary electron emission, but detailed mechanism has not been proven. In this paper, the effects of the interaction between the plasma and dielectric material are simulated with a two-dimensional particle-in-cell (PIC) code for the acceleration channel of the hall thruster. Especially, the simulation code is parallelized using graphic processing units (GPUs). To analyze the effect, the simulation is confirmed to change following two parameters, magnetic flux density and secondary electron emission coefficient (SEEC). The particle trajectory is presented with the variation of the SEEC and magnetic flux density as well as its curvature. This research is supported by a ``Core technology development of high Isp electric propulsion system for space exploration'' from National Space Lab. sponsored by the National Reshearch Foundation of korea (NRF).
Huang, Xiangdi; Li, Jing
2018-03-01
For the three-dimensional full compressible Navier-Stokes system describing the motion of a viscous, compressible, heat-conductive, and Newtonian polytropic fluid, we establish the global existence and uniqueness of classical solutions with smooth initial data which are of small energy but possibly large oscillations where the initial density is allowed to vanish. Moreover, for the initial data, which may be discontinuous and contain vacuum states, we also obtain the global existence of weak solutions. These results generalize previous ones on classical and weak solutions for initial density being strictly away from a vacuum, and are the first for global classical and weak solutions which may have large oscillations and can contain vacuum states.
Energy Technology Data Exchange (ETDEWEB)
Noguera, Norman, E-mail: norman.noguera@ucr.ac.cr [Departamento de Matemática, Universidad de Costa Rica. S.O (Costa Rica); Rózga, Krzysztof, E-mail: krzysztof.rozga@upr.edu [Department of Mathematical Sciences, University of Puerto Rico, Mayagüez, Puerto Rico 00681-5000 (United States)
2015-07-15
In this work, one provides a justification of the condition that is usually imposed on the parameters of the hypergeometric equation, related to the solutions of the stationary Schrödinger equation for the harmonic oscillator in two-dimensional constant curvature spaces, in order to determine the solutions which are square-integrable. One proves that in case of negative curvature, it is a necessary condition of square integrability and in case of positive curvature, a necessary condition of regularity. The proof is based on the analytic continuation formulas for the hypergeometric function. It is observed also that the same is true in case of a slightly more general potential than the one for harmonic oscillator.
Management of venous ulcers according to their anatomical relationship with varicose veins.
Lin, Yun-Nan; Hsieh, Tung-Ying; Huang, Shu-Hung; Liu, Chia-Ming; Chang, Kao-Ping; Lin, Sin-Daw
2018-02-01
Background Adequately excising varicose and incompetent perforating veins is necessary for reducing their recurrence rate of venous ulcer. Method In total, 66 venous ulcers (C6) in 1083 legs with primary varicose veins were managed through endoscopic-assisted surgery. In an endoscopic operative view, the nonvaricose, varicose, and incompetent perforating veins were clearly visualized and precisely dissected. The varicose and incompetent perforating veins were divided and completely excised. Result The varicose veins were traced to the base or periphery of the 55 ulcers. Moreover, 89.4% of the ulcers healed within 14 weeks. Kaplan-Meier analysis revealed a five-year recurrence rate of 0.0%, and the satisfaction mean score was 4.6. Conclusion Endoscopic-assisted surgery can be used to radically excise varicose veins complicated with venous ulcers; the surgery yields low recurrence and high satisfaction rates.
Varicose veins as a source of adult human endothelial cells.
Ryan, U S; White, L A
1985-01-01
Endothelial cells can be harvested from segments of adult human saphenous vein in a varicose condition removed from patients having single or bilateral vein ligation and stripping. The cells are harvested by scraping with a scalpel, seeded on to gelatin coated or Primaria flasks and are passaged by removal with a rubber policeman. The cells cultured in this manner are maintained in a growth medium that is not supplemented with growth factors. The cells grow with a cobblestone monolayer morphology, possess angiotensin converting enzyme activity and react with antibodies to Factor VIII antigen. The cells fluoresce brightly after reaction with monoclonal antibodies specific for human endothelial cells. Thus, stripped varicose vein segments provide a readily available source of endothelial cells.
Global search demand for varicose vein information on the internet.
El-Sheikha, Joseph
2015-09-01
Changes in internet search trends can provide healthcare professionals detailed information on prevalence of disease and symptoms. Chronic venous disease, more commonly known as varicose veins, is a common symptomatic disease among the adult population. This study aims to measure the change in global search demand for varicose vein information using Google over the past 8 years. The Google Trends instrument was used to measure the change in demand for the use of the local name for varicose veins in several countries across the world between January 2006 and December 2012. The measurements were normalised onto a scale relative to the largest volume of search requests received during a designated time and geographical location. Comparison of national levels of private healthcare and healthcare spending per capita to search demand was also undertaken using Organisation for Economic Co-operation and development economic measurements. Global interest has increased significantly, with linear regression demonstrating a 3.72% year-on-year increase in demand over the 8-year time period (r(2 )= 0.385, p search demand compared to cooler winter months (search demand (r(2 )= 0.120 p = 0.306). Healthcare spending per capita did not relate to search demand (r(2 )= 0.450 p = 0.077). There is increasing demand for information about varicose veins on the internet, especially during the warmer months of the year. Online search demand does not appear to be related to healthcare spending. © The Author(s) 2014.
Ertaş, Mehmet
2015-09-01
Keskin and Ertaş (2009) presented a study of the magnetic properties of a mixed spin (2, 5/2) ferrimagnetic Ising model within an oscillating magnetic field. They employed dynamic mean-field calculations to find the dynamic phase transition temperatures, the dynamic compensation points of the model and to present the dynamic phase diagrams. In this work, we extend the study and investigate the dynamic hysteresis behaviors for the two-dimensional (2D) mixed spin (2, 5/2) ferrimagnetic Ising model on a hexagonal lattice in an oscillating magnetic field within the framework of dynamic mean-field calculations. The dynamic hysteresis curves are obtained for both the ferromagnetic and antiferromagnetic interactions and the effects of the Hamiltonian parameters on the dynamic hysteresis behaviors are discussed in detail. The thermal behaviors of the coercivity and remanent magnetizations are also investigated. The results are compared with some theoretical and experimental works and a qualitatively good agreement is found. Finally, the dynamic phase diagrams depending on the frequency of an oscillating magnetic field in the plane of the reduced temperature versus magnetic field amplitude is examined and it is found that the dynamic phase diagrams display richer dynamic critical behavior for higher values of frequency than for lower values.
Open Surgery as of Pelvic Varicose Disease Management
Directory of Open Access Journals (Sweden)
Jhon Jairo Celis-Salas
2014-09-01
Full Text Available Chronic pelvic pain is a frequent condition for health care outpatient visits, which may occur in up to 40 % of women, and that significantly affects quality of life. The pelvic congestion syndrome associated with varicose veins is an etiological factor of this disease, but there is little evidence describing the efficacy and safety of the open surgical technique. This study evaluates the clinical results of open surgery for the management of pelvic varicose veins. Material and Methods: A cross sectional study with 94 patients with gonadal varix, who underwent open surgery, was conducted. We evaluated the diagnostic test findings, intra operative findings, and postoperative evolution. Results: 85 % of patients had bilateral reflux, and 15 % unilateral reflux. Over 70 % reported pelvic pain for more than six months, dyspareunia, dysmenorrhea, and urinary symptoms. Statistically significant differences were found when comparing the diameters reported in the duplex, with those measured intra-operatively, specifically of right gonadal vein, both in patients with unilateral (p = 0.022 and bilateral reflux (p = 0.017. 92% of the patients showed improvement of symptoms after surgical treatment. Conclusions: The ovarian vein ligation by open surgery is a therapeutic alternative for the treatment of pelvic varicose veins, with results demonstrating significant symptomatic improvement. The duplex is a useful diagnostic method, although the diameter of the gonadal veins may be underestimated.
Osherovich, V. A.; Fainberg, J.
2018-01-01
We consider simultaneous oscillations of electrons moving both along the axis of symmetry and also in the direction perpendicular to the axis. We derive a system of three nonlinear ordinary differential equations which describe self-similar oscillations of cold electrons in a constant proton density background (np = n0 = constant). These three equations represent an exact class of solutions. For weak nonlinear conditions, the frequency spectra of electric field oscillations exhibit split frequency behavior at the Langmuir frequency ωp0 and its harmonics, as well as presence of difference frequencies at low spectral values. For strong nonlinear conditions, the spectra contain peaks at frequencies with values ωp0(n +m √{2 }) , where n and m are integer numbers (positive and negative). We predict that both spectral types (weak and strong) should be observed in plasmas where axial symmetry may exist. To illustrate possible applications of our theory, we present a spectrum of electric field oscillations observed in situ in the solar wind by the WAVES experiment on the Wind spacecraft during the passage of a type III solar radio burst.
Kravtsov, P F; Katorkin, S A; Volkovoy, V V; Sizonenko, Ya V
Investigations of the influence of the training of the muscular component of the musculo-venous pump in the lower extremities on the clinical course of varicose vein disease and correction of the step cycle are currently underway. The objective of the present study was to evaluate the impact of the training of the muscular component of the musculo-venous pump in the lower extremities and of the correction of the step cycle on the quality of life of the patients presenting with varicose vein disease. The study included 22 patients with varicose veins in the lower extremities (CEAP clinical class C3 or C4). All the patients performed, twice daily during a total of 60 days, a specially designed complex of 7 exercise intended to strengthen the posterior muscle group of the lower legs and correct the step cycle. After 60 days, all the patients reported the appearance of the subjective signs suggesting positive dynamics of their condition. The following statistically significant changes were documented: reduction of the malleolar circumference, improvement of integral characteristics of the quality of life as evaluated with the use of the international questionnaire for the patients with chronic lower limb venous insufficiency (CIVIQ), normalization of the frequency and amplitude of modal oscillations in the soleus muscle revealed by electromyography. The correction of foot rolling muscles and the sequence of activation of the muscles involved in the first five phases of the cycle step increases the strength of contraction of the soleus muscle, promotes venous blood flow in the proximal direction, and thereby enhances the efficiency of the venous outflow. The development of adequate gain skills, the correction of the step cycle, and the strengthening of the muscular component of the musculo-venous pump lead to the improvement of the clinical course of varicose vein disease. The proposed complex of physical exercises provides an effective and pathogenetically sound
Corkidi, G; Montoya, F; Hernández-Herrera, P; Ríos-Herrera, W A; Müller, M F; Treviño, C L; Darszon, A
2017-09-01
Are there intracellular Ca2+ ([Ca2+]i) oscillations correlated with flagellar beating in human sperm? The results reveal statistically significant [Ca2+]i oscillations that are correlated with the human sperm flagellar beating frequency, when measured in three-dimensions (3D). Fast [Ca2+]i oscillations that are correlated to the beating flagellar frequency of cells swimming in a restricted volume have been detected in hamster sperm. To date, such findings have not been confirmed in any other mammalian sperm species. An important question that has remained regarding these observations is whether the fast [Ca2+]i oscillations are real or might they be due to remaining defocusing effects of the Z component arising from the 3D beating of the flagella. Healthy donors whose semen samples fulfill the WHO criteria between the age of 18-28 were selected. Cells from at least six different donors were utilized for analysis. Approximately the same number of experimental and control cells were analyzed. Motile cells were obtained by the swim-up technique and were loaded with Fluo-4 (Ca2+ sensitive dye) or with Calcein (Ca2+ insensitive dye). Ni2+ was used as a non-specific plasma membrane Ca2+ channel blocker. Fluorescence data and flagella position were acquired in 3D. Each cell was recorded for up to 5.6 s within a depth of 16 microns with a high speed camera (coupled to an image intensifier) acquiring at a rate of 3000 frames per second, while an oscillating objective vibrated at 90 Hz via a piezoelectric device. From these samples, eight experimental and nine control sperm cells were analyzed in both 2D and 3D. We have implemented a new system that allows [Ca2+]i measurements of the human sperm flagellum beating in 3D. These measurements reveal statistically significant [Ca2+]i oscillations that correlate with the flagellar beating frequency. These oscillations may arise from intracellular sources and/or Ca2+ transporters, as they were insensitive to external Ni2+, a non
International Nuclear Information System (INIS)
Chowdhury, A.; Yeo, I.; Tsvirkun, V.; Beaudoin, G.; Sagnes, I.; Raj, R.; Robert-Philip, I.; Raineri, F.; Braive, R.
2016-01-01
We investigate the non-linear mechanical dynamics of a nano-optomechanical mirror formed by a suspended membrane pierced by a photonic crystal. By applying to the mirror a periodic electrostatic force induced by interdigitated electrodes integrated below the membrane, we evidence superharmonic resonances of our nano-electro-mechanical system; the constant phase shift of the oscillator across the resonance tongues is observed on the onset of principal harmonic and subharmonic excitation regimes.
DEFF Research Database (Denmark)
Pihl, Michael Johannes; Jensen, Jørgen Arendt
2014-01-01
A method for 3-D velocity vector estimation us - ing transverse oscillations is presented. The method employs a 2-D transducer and decouples the velocity estimation into three orthogonal components, which are estimated simultane - ously and from the same data. The validity of the method...... also reveals, that the velocity estimation breaks down with an SNR between −6 and −3 dB. In terms of computational load, the estimation of the three velocity components requires 0.75 billion floating point operations per second (0.75 Gflops) for a realistic setup. This is well within the capability...
Temperature dependence of Coulomb oscillations in a few-layer two-dimensional WS2 quantum dot
Song, Xiang-Xiang; Zhang, Zhuo-Zhi; You, Jie; Liu, Di; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Guo, Guo-Ping
2015-11-01
Standard semiconductor fabrication techniques are used to fabricate a quantum dot (QD) made of WS2, where Coulomb oscillations were found. The full-width-at-half-maximum of the Coulomb peaks increases linearly with temperature while the height of the peaks remains almost independent of temperature, which is consistent with standard semiconductor QD theory. Unlike graphene etched QDs, where Coulomb peaks belonging to the same QD can have different temperature dependences, these results indicate the absence of the disordered confining potential. This difference in the potential-forming mechanism between graphene etched QDs and WS2 QDs may be the reason for the larger potential fluctuation found in graphene QDs.
Endovenous laser treatment of groin and popliteal varicose veins recurrence.
Cavallini, Alvise; Marcer, Daniela; Ferrari Ruffino, Salvatore
2018-04-01
Objectives Recurrent varicose veins following surgery is a common, complex and costly problem in vascular surgery. Treatment for RVV is technically more difficult to perform and patient satisfaction is poorer than after primary interventions. Nevertheless, traditional vein surgery has largely been replaced by percutaneous office-based procedures, and the patients with recurrent varicose veins have not benefited from the same advantages. In this paper, we propose an endovascular laser treatment that allows reducing the invasiveness and complications in case of SFJ and SPJ reflux after ligation and stripping of the great and small saphenous vein. Methods 8 SFJ and 1 SPJ stumps were treated by endovascular laser treatment in out-patient clinic. Endovascular laser treatment was performed with a 1470 nm diode laser and a 400 µc radial slim™ fiber. Intraoperative ultrasoud was used to guide the fiber position and the delivery of tumescent anesthesia. The gravity of chronic venous disease was determined according to the CEAP classification and the severity of symptoms was scored according to the revised Venous Clinical Severity Score (VCSS). Results The average linear endovenous energy density was 237 J/cm. Patients return to daily activities after a mean of 1.9 days after. The VCSS improved drastically from a mean of 8 pre-interventional to 1 at day 30 and until one year. During the follow-up period (mean 8 months, range: 5-17 months), all the stumps except one were occluded. All patients were very satisfied or satisfied with the method. No severe complications occurred. Conclusions Office-based endovascular laser treatment of groin and popliteal recurrent varicose veins with 1470 nm diode laser and radial-slim fiber is a safe and highly effective option, with a high success rate in the early post-operative period.
Shvetsov, O. O.; Kostarev, V. A.; Kononov, A.; Golyashov, V. A.; Kokh, K. A.; Tereshchenko, O. E.; Deviatov, E. V.
2017-09-01
We experimentally investigate Andreev transport through a single junction between an s-wave indium superconductor and a thick film of a three-dimensional Bi2Te3 topological insulator. We study Bi2Te3 samples with different bulk and surface characteristics, where the presence of a topological surface state is confirmed by direct ARPES measurements. All the junctions demonstrate Andreev transport within the superconducting gap. For junctions with transparent In-Bi2Te3 interfaces we find a number of nearly periodic conductance oscillations, which are accompanied by zero-bias conductance anomaly. Both effects disappear above the superconducting transition or for resistive junctions. We propose a consistent interpretation of both effects as originating from proximity-induced superconducting correlations within the Bi2Te3 topological surface state.
An integrated approach in the treatment of varicose ulcer
Directory of Open Access Journals (Sweden)
Deepa Patil
2013-01-01
Full Text Available Venous ulcers (stasis ulcers, varicose ulcers are the wounds occurring due to inappropriate functioning of venous valves, usually of the legs. It is one of the most serious chronic venous insufficiency complications. The overall incidence rate is 0.76% in men and 1.42% in women. When a venous valve gets damaged, it prevents the backflow of blood, which causes pressure in the veins that leads to hypertension and, in turn, venous ulcers. These are mostly along the medial distal leg, which is often very painful, can bleed, and get infected. Treating varicose ulcers is a difficult task to the physician and a nightmare to the suffering patients, though a good number of the treatment principles are mentioned and practiced in allied sciences. In Ayurveda, this condition is considered as dus.t.a vran.a. It can be managed with the specific s′odhana therapy. So, the same treatment protocol was used to treat the case discussed here, i.e. with Nitya virecana and by Basti karma. The wound was successfully treated and, therefore, is discussed in detail.
Varicose veins: a qualitative study to explore expectations and reasons for seeking treatment.
Palfreyman, Simon John; Drewery-Carter, Kim; Rigby, Kathryn; Michaels, Jonathan A; Tod, Angela Mary
2004-03-01
Patients experience a wide range of symptoms from varicose veins and are seeking treatment from health care providers. However, there is little data on the relative effectiveness of the treatments available. Patients are therefore often confronted with a choice regarding treatment that they are ill-equipped to make. This lack of certainty and the resultant potential for variability in treatment decisions can mean that patients have expectations that are unrealistic or unfulfilled. The aim of our study was to explore patients' expectations and reasons for seeking treatment for varicose veins. Additional aims included the exploration of symptoms associated with varicose veins and their impact on quality of life. Qualitative study conducted in a large NHS Trust. A total of 16 patients, who had been referred to a specialist vascular service for the treatment of varicose veins, were recruited. Semi-structured interviews were used to explore the patients' reasons for seeking treatment. Framework analysis was used to analyse the data from the anonymized transcripts. Participants attributed a wide range of symptoms to their varicose veins, and were actively seeking treatment with the expectation that they would gain symptom relief. The symptoms attributed to their varicose veins had a significant negative impact on their quality of life and lifestyle. Improving the cosmetic appearance of their legs was seen as a secondary benefit. The perceived symptoms of varicose veins can impact on lifestyle and quality of life. Patients seek treatment with the expectation of treatment outcomes that are not supported by robust clinical evidence. Appropriate education and management of such expectations are an essential step in caring for this group of patients. Nurses are caring for patients with varicose veins in a range of clinical settings. When caring and providing information for this group of patients, nurses need to be aware of the impact of varicose vein symptoms and to
International Nuclear Information System (INIS)
Barrow, J.D.
1983-01-01
The role played by the dimensions of space and space-time in determining the form of various physical laws and constants of Nature is examined. Low dimensional manifolds are also seen to possess special mathematical properties. The concept of fractal dimension is introduced and the recent renaissance of Kaluza-Klein theories obtained by dimensional reduction from higher dimensional gravity or supergravity theories is discussed. A formulation of the anthropic principle is suggested. (author)
Ebrahimi, Hossein; Amanpour, Farzaneh; Bolbol Haghighi, Nahid
2015-01-01
Venous diseases including varicose veins and chronic venous insufficiency are one of the most important pathogenic factors worldwide. High prevalence of varicose veins and its complications is an emerging problem in the twenty-first century. This study aimed to determine the prevalence and associated risk factors of varicose veins in female hairdressers in Shahroud, north of Iran in 2012. In this cross-sectional study, 197 employed hairdressers, licensed by the Health Department of Shahroud University of Medical Sciences, Iran, were studied. Standard physical examination was used to check the condition of varicose veins of the lower extremities of participants. Data were collected by demographic information form. Proportional odds model for ordinal logistic regression was used to assess the relationship between risk factors and status of varicose disease in subjects. Prevalence of varicose veins was 47.7%. Varicose veins were significantly associated with age (OR=1.08; 95% CI: 1.03, 1.13); family history of varicose disease (OR=1.99; 95% CI: 1.03, 3.82), blood pressure (OR=4.41; 95% CI: 1.63, 11.90); and duration of standing (OR=2.34; 95% CI: 1.05, 5.22). Varicose veins in the legs of female hairdressers had a high prevalence, and it was associated with increasing age, family history of varicose disease, high blood Pressure, and prolonged standing.
Radiofrequency ablation of varicose veins: Best practice techniques and evidence.
Goodyear, Stephen J; Nyamekye, Isaac K
2015-11-01
This article systematically reviews the practice of radiofrequency ablation of lower limb varicose veins. We present the clinical evidence and best practice techniques for currently available devices. Manufacturer's instructions-for-use were requested for all radiofrequency devices. The MEDLINE and EMBASE databases were searched using the following keywords: 'varicose veins' AND 'radiofrequency' OR 'radio frequency' OR 'Venefit' OR 'ClosureFAST' OR 'RFiTT' OR 'EVRF' OR 'VeinCLEAR', generating 240 articles. Titles and abstracts were screened, yielding 63 articles directly relevant to the scope of the review. Reference lists for publications were also searched to identify further manuscripts of relevance. The Cochrane Database and current National Institute for Clinical and Healthcare Excellence guidelines for varicose veins were also searched from relevant articles. Four radiofrequency ablation (RFA) systems are currently commercially available. Generic practice methods (common to all RF systems) and device-specific techniques are described. The weight of current evidence relates to the use of Covidien Venefit™ (formerly VNUS ClosureFAST™), which clearly demonstrates clinical advantages over open surgery at least to 2 years follow up. However, contemporary studies of the radiofrequency-induced thermal therapy device (RFiTT®), show that in experienced hands, clinical equivalence to the Venefit™ procedure can be achieved. The evidence base for EVRF® and VeinCLEAR™ devices is currently weak and absent, respectively. Despite widespread uptake of RFA and acceptance of its clinical advantages over open surgery there is a paucity of Class 1 A evidence. This results from incongruent reporting of clinical outcome measures within existing literature. Similarly, lack of long-term follow-up studies precludes comparison of the durability of short- and medium-term advantages of RFA with the longer term results of open surgery. There remains scope for a large prospective
Raman Scattering from Higgs Mode Oscillations in the Two-Dimensional Antiferromagnet Ca_{2}RuO_{4}.
Souliou, Sofia-Michaela; Chaloupka, Jiří; Khaliullin, Giniyat; Ryu, Gihun; Jain, Anil; Kim, B J; Le Tacon, Matthieu; Keimer, Bernhard
2017-08-11
We present and analyze Raman spectra of the Mott insulator Ca_{2}RuO_{4}, whose quasi-two-dimensional antiferromagnetic order has been described as a condensate of low-lying spin-orbit excitons with angular momentum J_{eff}=1. In the A_{g} polarization geometry, the amplitude (Higgs) mode of the spin-orbit condensate is directly probed in the scalar channel, thus avoiding infrared-singular magnon contributions. In the B_{1g} geometry, we observe a single-magnon peak as well as two-magnon and two-Higgs excitations. Model calculations using exact diagonalization quantitatively agree with the observations. Together with recent neutron scattering data, our study provides strong evidence for excitonic magnetism in Ca_{2}RuO_{4} and points out new perspectives for research on the Higgs mode in two dimensions.
Case Study Of Leech Application In Varicose Ulcer
Directory of Open Access Journals (Sweden)
Samaranayake G.V.P.
2015-08-01
Full Text Available Varicose ulcers are wounds that are thought to occur due to improper functioning of venous valves usually of the legs. They are the major occurrence of chronic wounds occurring in 70 to 90 of leg ulcer cases. In Sushrut Samhita where get the most scientific description of wound and its management. Similarly Sushrut has given the almost importance to Bloodletting therapy and considered leech as the most unique and effective method of bloodletting even in infected wounds and abscesses. Aforesaid description let us to try leech therapy in venous ulcer was advised to continue weekly application of leech around the ulcer which was followed by dressing with Seethodaka oil and Dashanga lepa. This leech therapy proved very effective and the ulcer healed completely within 30 days. However further evaluation is required to be done by taking a large samples size to prove its significant in treating Venous ulcer.
Patients' experiences of varicose vein and arthroscopy day surgery.
Fitzpatrick, J M; Selby, T T; While, A E
A small-scale telephone survey of day surgery patients' (n = 30) experience of pain, nausea and vomiting, wound healing and fatigue during the 7 days following discharge and their views of the service is described. Respondents who had undergone either varicose vein stripping (n = 15) or arthroscopy (n = 15) were interviewed using a semi-structured interview schedule. The findings indicated that most respondents expressed satisfaction with their recovery despite some evidence of postoperative morbidity. The majority of the sample indicated that they had received adequate information to enable them to cope at home and qualified nurses on the day unit were identified as a primary source of information. Following discharge, GPs or the day unit were key points of contact. The findings of this study, together with previous research, highlight important areas for further action by health professionals if this service is to be delivered effectively and efficiently.
Research on animal laser varicose treatment in CIOMP, CAS
Zhang, Laiming; Li, Dianjun; Lu, Qipeng; Yang, Guilong; Guo, Jin
2007-05-01
The work on laser varicose treatment carried out in CIOMP, CAS cooperating with The First Clinical Hospital, Jilin University is summarized. Dozens of animal experiments adopting dog and rabbit samples are made in a long time of several years. Different lasers are used, including long pulse frequency-doubled Nd:YAG(532nm) and semiconductor laser(808nm). Dozens of animal experiments show that laser has good efficacy to occlude the vein vessels. It has precise adjustability and relatively short treatment time only needing outpatient office setting with high cost and effect rate; It provides minimal invasion, often under local anesthesia and intravenous sedation thereby eliminating the need for general anesthesia, greatly shortens postoperative recovery term, and it is highly safe with no side effects and no serious complications.
Ultrasound surveillance in endoluminal laser treatment for varicose veins
Directory of Open Access Journals (Sweden)
Varetto G
2013-10-01
Full Text Available Gianfranco Varetto, Paolo Garneri, Claudio Castagno, Valentina Molinaro, Simone Quaglino, Matteo Ripepi, Emilio Benintende, Lorenzo Gibello, Stefano Zan, Luigi Contessa, Ugo Bertoldo, Pietro Rispoli Vascular Surgery, Department of Surgical Sciences, University of Turin, Turin, Italy Abstract: Venous ultrasonography is an indispensable tool in minimally invasive surgery for the treatment of varicose veins. However, the criteria for defining preoperative imaging parameters, outcome monitoring, and follow up are not well characterized. In this retrospective study, we reviewed the ultrasound periprocedural parameters and the outcomes in 274 patients (280 limbs after endoluminal laser treatment, at early (<30 days and late (1–60 months follow up. Treatment failure was defined as complete recanalization of the saphenous trunk, thigh perforator vein insufficiency, and recanalization of the proximal saphenous trunk. Judicious patient selection correlated with favorable outcome at the follow-up ultrasound examination. Keywords: follow-up, chronic venous disease, intravenous, obliteration
Evidence for varicose vein surgery in venous leg ulceration.
Kheirelseid, Elrasheid A H; Bashar, Khalid; Aherne, Thomas; Babiker, Thamir; Naughton, Peter; Moneley, Daragh; Walsh, Stewart R; Leahy, Austin L
2016-08-01
Venous leg ulcers affect 1-3% of adults with a significant economic impact, utilizing 1% of annual healthcare budgets in some western European countries. To determine the effects of intervention for incompetent superficial veins on ulcer healing and recurrence in patients with active or healed venous ulcers. In October 2014, we searched Medline, CINAHL, EMBASE, Scopus, the Cochrane library and Web of Science without date or language restriction for relevant randomized or observational studies. Bibliographies of included studies were also searched for additional studies. Observational studies or randomized controlled trials comparing intervention for varicose veins with compression therapy alone for venous leg ulcers were eligible. In addition, studies compared open to endovenous therapy for varicose veins in patients with leg ulcers and those compared treating saphenous and perforating veins to treating saphenous veins only were also included. Studies had to report at least one ulcer-related outcome (healing rate, recurrence or time to healing). Details of potentially eligible studies were extracted and summarized using a data extraction table. Data extraction and quality assessment were performed independently by two review authors, and any disagreements resolved by consensus or by arbitration of a third author. Intervention for superficial venous reflux improved ulcer healing (risk ratio = 1.11 [1.00, 1.22], 95% CI, p = 0.04) and reduced recurrence (risk ratio = 0.48 [0.32, 0.67], 95% CI, p venous leg ulcer is at beast weak. A well-structured RCT is required to investigate the role of endovenous ablation of incompetent superficial veins in improving venous leg ulcer outcomes. Copyright © 2016 Royal College of Surgeons of Edinburgh (Scottish charity number SC005317) and Royal College of Surgeons in Ireland. Published by Elsevier Ltd. All rights reserved.
A review of a new Dutch guideline for management of recurrent varicose veins.
Lawson, James A; Toonder, Irwin M
2016-03-01
In 2013, the new Dutch guideline for "Venous Pathology" was published. The guideline was a revision and update from the guideline "Diagnostics and Treatment of Varicose Veins" from 2009 and the guideline "Venous Ulcer" from 2005. A guideline for "Deep Venous Pathology" and one for "Compression Therapy" was added to the overall guideline "Venous Pathology." The chapter about treatment of recurrent varicose veins after initial intervention was recently updated in 2015 and is reviewed here. The Dutch term "recidief varices" or the French "récidive de varices" should be used analogous to the English term "recurrent varicose veins." The DCOP Guideline Development Group Neovarices concluded that "recidief" in Dutch actually suggests recurrence after apparent successful treatment and ignores the natural progression of venous disease in its own right. So the group opted to use the term "neovarices." In the Dutch guideline, neovarices is meant to be an all embracing term for recurrent varicose veins caused by technical or tactical failure, evolvement from residual refluxing veins or natural progression of varicose vein disease at different locations of the treated leg after intervention. This report reviews the most important issues in the treatment of varicose vein recurrence, and discusses conclusions and recommendations of the Dutch Neovarices Guideline Committee. © The Author(s) 2016.
Evaluation of apoptosis in varicose vein disease complicated by superficial vein thrombosis.
Filis, Konstantinos; Kavantzas, Nikolaos; Dalainas, Ilias; Galyfos, George; Karanikola, Evridiki; Toutouzas, Konstantinos; Tsioufis, Constantinos; Sigala, Fragiska
2014-07-01
The factors contributing to superficial vein thrombosis (SVT) in patients with varicose vein disease are unclear. Differences in vein wall apoptotic activity could be associated with the pathogenesis of SVT. The aim of the study is to address the role of the programmed cell death in the vein wall by comparing varicose veins with history of SVT to uncomplicated varicose veins. Vein segments from the proximal part of the great saphenous vein (GSV), the distal part of the vein and from a varicose tributary, from 16 patients with varicose vein disease and one episode of SVT, were evaluated for the immunohistochemical expression of pro-apoptotic (Bax, p53, Caspase 3, BCL-6, BCL-xs), anti-apoptotic (BCL-xl and BCL-2) and proliferation (Ki-67) markers. The results of this study were compared to the results from the evaluation of 19 patients suffering from uncomplicated varicose vein disease and 10 healthy GSVs as controls. Overall, there was increased apoptosis in the distal part of GSV compared to the proximal part documented by increased expression of Bax (p veins and patients with a history of SVT showed significant differences among the three different anatomic locations. In the proximal GSV, only BCL-xs was higher in patients with SVT (p = 0.029). In the tributaries, Bax, BCL-xl and Ki-67 were higher in patients with SVT (p thrombosis group compared to uncomplicated veins (p vein wall in SVT shows increased pro-apoptotic activity compared to uncomplicated disease and normal veins. Whether increased vein wall cell apoptosis is a causative factor for SVT in varicose veins disease or a repairing mechanism of the thrombosis itself needs further research.
Brandão, P. A.; Cavalcanti, S. B.
2017-10-01
Propagation of wide optical beams in transverse periodic lattices have been reported to induce power oscillations between Fourier modes related by the Bragg resonance condition, resulting from the coupling between the beam and the periodic structure. These oscillations have been referred to as Rabi optical oscillations due to the analogy with matter Rabi oscillations. In this work, we investigate the behavior of Bragg-induced Rabi-type oscillations of a multimode Gaussian beam in the presence of optical nonlinearity. We find a combination of oscillation and spectrum broadening under both self-focusing and self-defocusing nonlinearities, in the sense that the oscillations are maintained while the spectrum is broadened and therefore partially transferred to the twin frequency. For intense self-focusing nonlinearities a complete leak of the initial mode profile to other modes is rapidly attained so that no oscillation is observed. In contrast, for intense self-defocusing nonlinearities the redistribution rate is so dramatic that oscillations cease and power only fades away.
Recurrence of superficial vein thrombosis in patients with varicose veins.
Karathanos, Christos; Spanos, Konstantinos; Saleptsis, Vassileios; Tsezou, Aspasia; Kyriakou, Despina; Giannoukas, Athanasios D
2016-08-01
To investigate which factors other than history of superficial vein thrombosis (SVT) are associated with recurrent spontaneous SVT episodes in patients with varicose veins (VVs). Patients with a history of spontaneous SVT and VVs were followed up for a mean period of 55 months. Demographics, comorbidities, and thrombophilia screening test were analyzed. Patients were grouped according to the clinical-etiology-anatomy-pathophysiology classification. A multiple logistic regression analysis with the forward likelihood ratio method was undertaken. Thirteen patients out of 97 had a recurrence SVT episode during the follow-up period. All those patients were identified to have a thrombophilia defect. Protein C and S, antithrombin, and plasminogen deficiencies were more frequently present in patients without recurrence. Gene mutations were present in 38% in the nonrecurrence group and 77% in the recurrence group. After logistic regression analysis, patients with dislipidemia and mutation in prothrombin G20210A (FII) had an increased risk for recurrence by 5.4-fold and 4.6-fold, respectively. No deep vein thrombosis or pulmonary embolism occurred. Dislipidemia and gene mutations of F II are associated with SVT recurrence in patients with VVs. A selection of patients may benefit from anticoagulation in the short term and from VVs intervention in the long term. © The Author(s) 2015.
Baggen, Vivan J M; Chung, Kaman; Koole, Koos; Sarneel, Michelle H J; Rutten, Frans H|info:eu-repo/dai/nl/189152753; Hajer, Gideon R
2015-01-01
BACKGROUND: In patients with superficial venous thrombosis (SVT) co-existence of deep venous thrombosis (DVT) can be present. Varicosities are considered as a risk factor for both SVT and DVT separately. However, current evidence is contradictory whether varicosities are associated with an increased
The supersymmetric Pegg-Barnett oscillator
International Nuclear Information System (INIS)
Shen, Jian Qi
2005-01-01
The su(n) Lie algebraic structure of the Pegg-Barnett oscillator that possesses a finite-dimensional number-state space is demonstrated. The supersymmetric generalization of the Pegg-Barnett oscillator is suggested. it is shown that such a supersymmetric Pegg-Barnett oscillator may have some potential applications, e.g., the mass spectrum of the charged leptons
Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz
1995-01-01
Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.
Shirasugi, Nozomu; Horiguchi, Sadaaki; Shirato, Hiroyuki; Kawakami, Toshimitsu; Ono, Hisako; Yabuki, Shiho; Jojima, Kumiko; Niimi, Masanori
2016-01-01
Prevalence of asymptomatic deep vein thrombosis (DVT) in patients with primary varicose veins remains unclear. Here, we conducted a retrospective study to clarify the incidence of asymptomatic DVT in patients with varicose veins, especially focusing on those with superficial thrombophlebitis (STP). Among 431 patients with primary varicose veins with saphenous vein incompetence, 20 (4.64%) had asymptomatic DVT. The presence of STP was a significant risk factor for asymptomatic DVT as 10 of the 24 (41.7%) patients with STP had asymptomatic DVT, and all cases having calf muscle vein thrombosis. In contrast, of the patients with primary varicose veins without STP only 2.46% had asymptomatic DVT. In patients with primary varicose veins with STP, significant risk factors for DVT were being over C3 on the clinical, etiological, anatomical, and pathophysiological (CEAP) classification. (This article is a translation of Jpn J Phlebol 2014; 25: 13-19.).
Unusual death due to a bleeding from a varicose vein: a case report
Directory of Open Access Journals (Sweden)
Fragkouli Kleio
2012-09-01
Full Text Available Abstract Background Varicose veins are a common entity presenting a worldwide distribution. Although they are usually benign, sometimes are proved to be a threatening condition. Massive hemorrhage is an unusual complication of this common venous pathology that demands immediate medical intervention. Case presentation We present a case of a 66-year-old woman found dead in her house surrounded by a large quantity of blood. Autopsy revealed a 7 mm ulcer on the internal surface of the left lower leg communicating with a varicose vein, signs of exsanguinations and liver cirrhosis. Toxicological analysis was negative. Conclusion Massive hemorrhage from a ruptured varicosity is a severe medical emergency. Awareness of the risk of massive hemorrhage may provoke preventive treatment to be undertaken so as terminal loss of consciousness and a subsequent unattended death to be averted.
Cheng, Guanglei; Annadi, Anil; Lu, Shicheng; Lee, Hyungwoo; Lee, Jung-Woo; Huang, Mengchen; Eom, Chang-Beom; Irvin, Patrick; Levy, Jeremy
2018-02-01
The widely reported magnetoresistance oscillations in LaAlO3/SrTiO3 heterostructures have invariably been attributed to the Shubnikov-de Haas (SdH) effect, despite a pronounced inconsistency with low-field Hall resistance measurements. Here we report SdH-like resistance oscillations in quasi-1D electron waveguides created at the LaAlO3/SrTiO3 interface by conductive atomic force microscopy lithography. These oscillations can be directly attributed to magnetic depopulation of magnetoelectric subbands. Our results suggest that the SdH oscillations in 2D SrTiO3 -based systems may originate from naturally forming quasi-1D channels.
Indian Academy of Sciences (India)
Neutrino Oscillations: New Windows to the Particle World. General Article Volume 21 Issue 10 ... Neutrino oscillation is a quantum mechanicalphenomenon whereby a neutrino created witha specific lepton flavour (electron, muon, or tau) can later bemeasured to have a different flavour. Historical developmentof the field in ...
Indian Academy of Sciences (India)
The law of mass-action led chemists to the belief that reactions approach equilibrium steadily. So the discovery of chemical oscillations came as a surprise. Now chemists are very familiar with reactions that oscillate in time and/or space. Experimental and theoretical studies of such reac- tions showing temporal and spatial ...
Varicose veins in the lower extremities in relation to occupational mechanical exposures
DEFF Research Database (Denmark)
Tabatabaeifar, Sorosh; Frost, Poul; Andersen, Johan Hviid
2015-01-01
OBJECTIVES: To evaluate if occupational mechanical exposures are associated with an increased risk of surgery for varicose veins (VV) in the lower extremities. METHODS: We conducted a longitudinal study of persons from the Musculoskeletal Research Database at the Danish Ramazzini Centre who were 18...
Poluektova, Anna A.; Malskat, Wendy S. J.; van Gemert, Martin J. C.; Vuylsteke, Marc E.; Bruijninckx, Cornelis M. A.; Neumann, H. A. Martino; van der Geld, Cees W. M.
2014-01-01
Minimally invasive treatment of varicose veins by endovenous laser ablation (EVLA) becomes more and more popular. However, despite significant research efforts performed during the last years, there is still a lack of agreement regarding EVLA mechanisms and therapeutic strategies. The aim of this
Study to develop a waiting list prioritization score for varicose vein surgery.
Bellmunt Montoya, Sergi; Sirvent González, Marc; Florit López, Salvador; Dilmé Muñoz, Jaume; Giménez Gaibar, Antonio; Escudero Rodríguez, José Román
2014-02-01
The objective of this study was to develop a clear-cut, objective system for prioritization of patients on the waiting list for varicose vein surgery, to enable organization of access to the health service. During earlier phases, we selected which variables should be taken into account for the prioritization scale, such as clinical presentation, varicose vein size, complications, work situation, and influence on quality of life. In the last phase, to determine the relative weight of each variable, structured surveys (personal interviews or by e-mail) were performed of the convenience samples from the groups related to the healthcare process, including patients, relatives, and healthcare professionals. The structured survey we utilized was administered to a sample of 762 subjects that included 290 patients, 99 relatives, 179 general practitioners, 32 nurses, and 162 vascular surgeons. The final score included clinical manifestations (46.1% of relative importance), size of the varicose veins (8.2%), complications (18.3%), influence on quality of life (18.2%), and aggravating work factors (9.2%). The prioritization system agreed upon by all the groups involved could allow for objective and transparent prioritization and lead to the rationalization of access to varicose vein surgery for patients on the waiting list. Copyright © 2014 Elsevier Inc. All rights reserved.
de Maeseneer, M. G.; Giuliani, D. R.; van Schil, P. E.; de Hert, S. G.
2002-01-01
OBJECTIVES: To investigate whether a silicone implant at the sapheno-femoral ligation site could prevent recurrent varicosities. MATERIALS AND METHODS: Two non-randomised groups of patients were studied prospectively. In group A 173 patients and 212 limbs had sapheno-femoral ligation, while 172
Optical-thermal mathematical model for endovenous laser ablation of varicose veins
P.W.M. van Ruijven (Peter); A.A. Poluektova (Anna); M.J.C. van Gemert (Martin); H.A.M. Neumann (Martino); T.E.C. Nijsten (Tamar); C.W.M. van der Geld (Cees)
2014-01-01
textabstractEndovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of
Optical-thermal mathematical model for endovenous laser ablation of varicose veins
van Ruijven, Peter W. M.; Poluektova, Anna A.; van Gemert, Martin J. C.; Neumann, H. A. Martino; Nijsten, Tamar; van der Geld, Cees W. M.
2014-01-01
Endovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of the various
A multicenter review of epidemiology and management of varicose veins for national guidance
Directory of Open Access Journals (Sweden)
Nitin Joseph
2016-06-01
Conclusion: The high risk groups identified in this study need to be made aware of risk of developing varicose veins. Use of compression stocking at work place added with newer procedure in management could help in betterment in their quality of life.
Superficial vein thrombosis in non-varicose veins of the lower limbs and thrombophilia.
Lucchi, Gabriella; Bilancini, Salvino; Tucci, Sandro; Lucchi, Massimo
2017-01-01
Objectives Superficial vein thrombosis in non-varicose veins of the lower limbs is rather frequent and may be underestimated. This study aims to evaluate the prevalence of inherited or acquired thrombophilia in a sample of outpatients with the disease. Method An observational study was conducted on 73 consecutive superficial vein thrombosis patients tested for inherited or acquired thrombophilia. Results Sixty of 73 patients with superficial vein thrombosis completed the testing protocol, while 13 dropped out; 46 of 60 patients were found to have a thrombophilia (76.6%). The types detected were: factor V Leiden (31/60, i.e. 51.6%), prothrombin mutation (2/60, i.e. 3.3%), MTHFR mutation (23/60, i.e. 38.3%), antiphospholipid antibodies (5/60, i.e. 8.3%), protein C deficit (1/60, i.e. 1.6%), protein S deficit (1/60, i.e. 1.6%), and antithrombin deficit (0/60, i.e. 0%). Conclusions Among patients with superficial vein thrombosis in non-varicose veins, testing demonstrated a high prevalence of thrombophilia. The most common form proved to be factor V Leiden. As thrombophilia was found to be a major cause of superficial vein thrombosis in non-varicose veins, the authors recommend that patients with superficial vein thrombosis in non-varicose veins be investigated for thrombophilia.
YouTube as a source of information on varicose veins.
Güneş, Tevfik; Serinken, Mustafa; Alur, İhsan; Beydilli, Halil; Karcioglu, Ozgur; Eken, Cenker
2016-08-01
There has been little investigation of videos related to varicose veins in Internet media. This study aimed to investigate the characteristics and scientific accuracy of the videos related to varicose veins which were uploaded to the youtube.com website. The YouTube site was searched in October 2014 using the keywords varicose vein, varicose veins, and varicosis with no filter. The contents of the reviewed videos were assigned to three groups as useful, partly useful, and not useful by using the criteria including the scientific contents of the videos, contemporariness and accuracy of the insight, and presentation of the data particularly regarding the visual features. The statistical analysis was based only on the videos rated as 'useful.' In total, 1519 (84.4%) of 1800 videos evaluated were excluded. Many of the sources uploading videos to the website were healthcare professionals (32.7% n = 92). Regarding the source of the upload, those from official institutions/associations were viewed statistically significantly more often than videos uploaded by all others (p = 0.001). The rated usefulness was significantly higher for videos uploaded by official institutions/associations (100%) than those uploaded by others (p = 0.01). Official institutions/associations should be encouraged to produce and upload videos including up-to-date and comprehensive information regarding the disease. Likewise, additional search tools would be useful to locate videos uploaded by academic figures and institutions. © The Author(s) 2015.
Hudson, Briony F; Ogden, Jane; Whiteley, Mark S
2015-06-01
To gain insight into the experience of living with varicose veins and undergoing minimally invasive surgery under local anaesthesia in a private clinic. Minimally invasive surgery under local anaesthesia is replacing traditional surgical stripping for the treatment for varicose veins. Conscious surgery has previously been associated with elevated levels of anxiety and some associated pain. There is limited research exploring the experiences of patients undergoing varicose vein surgery under local anaesthesia. Qualitative semi-structured interviews with 20 patients who took part in a mixed methods study exploring the effects of distraction on intra-operative pain and anxiety. Participants were interviewed eight weeks post surgery about their experiences before, during and after surgery. Interviews were analysed using thematic analysis. Four themes were captured (1) negative emotions associated with symptoms, (2) unpreparedness for the surgical process, (3) feeling cared for and (4) improvements in well-being. An overarching theme of relationships was identified. Overall, varicose veins had a detrimental impact on quality of life prior to surgery. Patients felt unprepared for their procedure and experienced the operation as anxiety provoking and uncomfortable. This was much helped by the support of nursing staff in the theatre. Post surgery, patients' quality of life was reported as improved. More emphasis needs to be placed on preparing patients for surgery under local anaesthesia. The role of the nurse is central to creating a caring, relaxed environment which could improve patient experience. Patients' experiences of varicose veins and their treatment both influence, and are influenced by relationships with others at all stages of the management process. Nurses play an important role in improving patient experience during surgery and care needs to be taken to ensure that patients understand and accept the processes of surgery and recovery. © 2015 John Wiley
Ishibashi, Hiroki; Miyamoto, Morikazu; Shinnmoto, Hiroshi; Murakami, Wakana; Soyama, Hiroaki; Nakatsuka, Masaya; Natsuyama, Takahiro; Yoshida, Masashi; Takano, Masashi; Furuya, Kenichi
2017-10-01
The aim of this study was to prenatally predict placenta accreta in posterior placenta previa using magnetic resonance imaging (MRI). This retrospective study was approved by the Institutional Review Board of our hospital. We identified 81 patients with singleton pregnancy who had undergone cesarean section due to posterior placenta previa at our hospital between January 2012 and December 2016. We calculated the sensitivity and specificity of several well-known findings, and of cervical varicosities quantified using magnetic resonance imaging, in predicting placenta accreta in posterior placenta previa. To quantify cervical varicosities, we calculated the A/B ratio, where "A" was the minimum distance from the most dorsal cervical varicosity to the deciduous placenta, and "B" was the minimum distance from the most dorsal cervical varicosity to the amniotic placenta. The appropriate cut-off value of the A/B ratio was determined using a receiver operating characteristic (ROC) curve. Three patients (3.7%) were diagnosed as having placenta accreta. The sensitivity and specificity of the well-known findings were 0 and 97.4%, respectively. Furthermore, the A/B ratio ranged from 0.02 to 0.79. ROC curve analysis revealed that the area under the combined placenta accreta and A/B ratio curve was 0.96. When the cutoff value of the A/B ratio was set 0.18, the sensitivity and specificity were 100 and 91%, respectively. It was difficult to diagnose placenta accreta in the posterior placenta previa using the well-known findings. The quantification of cervical varicosities could effectively predict placenta accreta.
Clinical course and effective treatment of varicose vein of lower limb in diabetic patients
Directory of Open Access Journals (Sweden)
Yu.O. Syniachenko
2017-02-01
Full Text Available Background. Type 2 diabetes mellitus (DM2 is a risk factor for arteriosclerosis of the lower extremities, and the relationship with the state of the feet venous vascular territory remains insufficiently studied, the effectiveness of surgical treatment of patients with varicose veins is not defined. Objective: to analyze the clinical course of foot varicose veins and the effectiveness of medical measures on the background of DM2. Materials and methods. The study included 302 patients (227 men and 75 women aged 29–72 years old, 16 % of which had previous phlebothrombosis and the prevalece of II, III, IV, V and VI class of venous insufficiency was 10, 14, 37 16 and 23 %, respectively. 263 patients underwent endovenous laser coagulation, and 39 — the traditional phlebectomy and ligation of perforating veins. Results. Among the examined patients with varicose veins of lower extremities DM2 was diagnosed in 9 % of cases, more often in males and elderly patients on the background of atherosclerosis of the foot vessels (iliac, femoral, tibial, popliteal artery, which was accompanied by more frequent involvement of the great saphenous vein in the process and its gate extension, the prevalence of severe grades of venous insufficiency, significantly worse the results of surgical treatment of varicose veins and greater frequency of complications, despite more frequent using of rivaroxaban and low molecular weight heparins, and the effectiveness of endovenous laser ablation after four weeks of its implementation is inferior to that in the group without DM2, while glycemic index inversely correlated with the surface tension of the venous blood, which has prognostic significance in the context of future medical interventions. Conclusions. The presence of DM2 is a risk factor for more severe feet varicose veins, is a negative predictive factor in the effectiveness of surgical treatment of the disease and the complications number.
Oscillating universe with quintom matter
International Nuclear Information System (INIS)
Xiong Huahui; Cai Yifu; Qiu Taotao; Piao Yunsong; Zhang Xinmin
2008-01-01
In this Letter, we study the possibility of building a model of the oscillating universe with quintom matter in the framework of 4-dimensional Friedmann-Robertson-Walker background. Taking the two-scalar-field quintom model as an example, we find in the model parameter space there are five different types of solutions which correspond to: (I) a cyclic universe with the minimal and maximal values of the scale factor remaining the same in every cycle, (II) an oscillating universe with its minimal and maximal values of the scale factor increasing cycle by cycle, (III) an oscillating universe with its scale factor always increasing, (IV) an oscillating universe with its minimal and maximal values of the scale factor decreasing cycle by cycle, and (V) an oscillating universe with its scale factor always decreasing
DEFF Research Database (Denmark)
Klitfod, Lotte; Sillesen, Henrik; Jensen, Leif Panduro
2018-01-01
Objective Quality improvement in surgery has mainly been based on clinical database outcomes. This study compared variables from the patient-reported Aberdeen Varicose Vein Questionnaire with the Danish Clinical Vein Database, in order to reveal agreements and differences in symptoms and clinical...... or more complaints still present in 128 (93%) patients according to Aberdeen Varicose Vein Questionnaire compared to the Danish Clinical Vein Database with only 64 (47%) patients. Patients reported cosmetic complaints and teleangiectasies both before and after treatment (p
Directory of Open Access Journals (Sweden)
M. Mahbobi
2010-04-01
Full Text Available Background and aims varicose of lower limbs is one of the most common injuries which is caused and intensified by the job activities through passing the time and can cause the person and the society to bear the high cost. This study has been done in order to investigate the relationship between the demographic and occupational factors with the lower limb varicose severity of the nurses in Amol hospital. Methods This cross-sectional study was conducted through on 203 nurses in Amol hospitals. Questionnaire was used to collect the required information. It was completed through interview and physical examination based on the standard CEAP forms. Results 145 of the subjects were female. 73.9% of the nurses had varicose with different levels (CI95%: 77- 65. Female gender, age, BMI (OR =1.21, regular exercise (OR =0.31, family history, weight, and overtime between job factors (OR =1.01, years of service, standing (OR =2.3 and sitting in the ward had significant relationship with the varicose intensity. Conclusion It seems that the necessary training to reduce disability and treatment expenses to adjust risk factors and prevention of inducing varicose is essential according to the high number of the nurses who have lower varicose veins with different intensities and the effect of lots of demographic and occupational factors.
Reverse Regulatory Pathway (H2S / PGE2 / MMP in Human Aortic Aneurysm and Saphenous Vein Varicosity.
Directory of Open Access Journals (Sweden)
Ingrid Gomez
Full Text Available Hydrogen sulfide (H2S is a mediator with demonstrated protective effects for the cardiovascular system. On the other hand, prostaglandin (PGE2 is involved in vascular wall remodeling by regulating matrix metalloproteinase (MMP activities. We tested the hypothesis that endogenous H2S may modulate PGE2, MMP-1 activity and endogenous tissue inhibitors of MMPs (TIMP-1/-2. This regulatory pathway could be involved in thinning of abdominal aortic aneurysm (AAA and thickening of saphenous vein (SV varicosities. The expression of the enzyme responsible for H2S synthesis, cystathionine-γ-lyase (CSE and its activity, were significantly higher in varicose vein as compared to SV. On the contrary, the endogenous H2S level and CSE expression were lower in AAA as compared to healthy aorta (HA. Endogenous H2S was responsible for inhibition of PGE2 synthesis mostly in varicose veins and HA. A similar effect was observed with exogenous H2S and consequently decreasing active MMP-1/TIMP ratios in SV and varicose veins. In contrast, in AAA, higher levels of PGE2 and active MMP-1/TIMP ratios were found versus HA. These findings suggest that differences in H2S content in AAA and varicose veins modulate endogenous PGE2 production and consequently the MMP/TIMP ratio. This mechanism may be crucial in vascular wall remodeling observed in different vascular pathologies (aneurysm, varicosities, atherosclerosis and pulmonary hypertension.
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Indian Academy of Sciences (India)
behaviour of a few complex chemical systems. We observed that these chemical oscillators are basically .... Kutta fourth order integration method to solve the Lotka-. Volterra equation as per the Fortran program given in ... This is known as the phase plane represen- tation. We have obtained these plots using the software.
Indian Academy of Sciences (India)
relevant species is zero. So, oscillations can appear only if the inhibition step is somehow .... the value of such an experimental parameter can possi- bly move the system between the steady states. Per- ... states for different values of [X], obtained far from equilibrium. Figure 2. System showing. The concentrations [X] ...
Heat transfer with oscillating pressure and oscillating flow
Kornhauser, Alan A.; Smith, Joseph L., Jr.
Heat exchangers in Stirling engines and many other reciprocating machines operating under conditions of both oscillating pressure and oscillating flow are discussed. Experiments were done on an apparatus consisting of a piston-cylinder space connected to an annular dead-end heat exchanger space. Instantaneous heat flux and center gas temperature were measured at six locations along the heat exchanger. The results were used to test the model, with the complex Nusselt number correlated against oscillating-flow Peclet number. The experimental results showed that the complex Nusselt number was capable of predicting the heat flux, but that there was at least one other important independent variable besides oscillating-flow Peclet number. Dimensional analysis suggested that this was either the ratio of gas thermal properties to those of the wall or a measure of compressibility effects.
Can deep vein thrombosis be predicted after varicose vein operation in women in rural areas?
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Marcin Warot
2014-09-01
Full Text Available [b]Introduction[/b]. Chronic venous disease is a group of symptoms caused by functional and structural defects of the venous vessels. One of the most common aspects of this disease is the occurrence of varicose veins. There are many ways of prevention and treatment of varicose veins, but in Poland the leading one is still surgery. As in every medical procedure there is the possibility of some complications. One of them is deep vein thrombosis (DVT. The diagnosis of DVT can be difficult, especially when access to a specialist is limited, such as in case of rural patients. [b]The aim of the study.[/b] The aim of the study was estimation of the influence of LMWH primary prophylaxis on the formation of postoperative DVT, as well as sensitivity and specificity of clinical examination and D-dimer value in diagnosis of postoperative DVT in women. [b]Materials and methods[/b]. The study was conducted in a group of 93 women operated on in the Department of General, Vascular Surgery and Angiology at the Karol Marcinkowski University of Medical Sciences in Poznań, Poland. The patients had undergone a varicose vein operation and were randomly divided into two groups: A – 48 women receiving LMWH during two days of the perioperative period, B – 45 women receiving LMWH during seven days of the perioperative period. [b]Results[/b]. There was no significant difference in the postoperative DVT complications in both groups. The value of D-dimer > 0.987 mcg/ml and swelling > 1.5 cm of shin (in comparison to the preoperative period plays a significant role in diagnosis of DVT. [b]Conclusions[/b]. The extended primary prophylaxis with LMWH does not affect the amount or quality of thrombotic complications after varicose vein operation. If the DVT occurs, the evaluation of the D – dimer and careful clinical examination can be a useful method for its diagnosis.
Sadick, Neil S
2006-01-01
Dermatologists have played a key role in the advancement and development of new safe, noninvasive technologies that are utilized in the treatment of both cosmetic telangiectasias and larger varicose veins of medical significance. As presented in this article, major advances in sclerosing solutions, hook avulsion techniques, and endovascular RF and laser procedures have revolutionized the world of phlebology. This medical sector continues to evolve through its relevance to the ever-expanding aesthetic and aging population.
Jerkic, Zoran; Karic, Alen; Karic, Amela
2009-01-01
Although superficial thrombophlebitis is a common disorder until recently it was considered as benign disorder. Also it is associated with varicose vein at legs and it was treated effectively with conservative methods, walking and non-steroid anti-inflammatory drugs. Aims of our investigation were: determine frequency of clinically silent deep vein thrombosis at legs in patient with and without superficial thrombophlebitis, determine correlation between superficial thrombophlebitis and deep vein thrombosis regardless of localization of superficial thrombophlebitis in superficial veins of legs and determine adequacy and safety vein phlebography in early diagnosis clinically silent deep vein thrombosis in patients with superficial thrombophlebitis. Using flebography in prospective study was evaluated incidence of clinically silent deep vein thrombosis in 92 patients with varicose veins at legs. By phlebograpy in patients with varicose veins at legs and superficial thrombophlebitis at legs and without clinical signs of DVT at legs of the 49 patients we detected DVT in 12 patients (24, 48%), in three male and nine female. We detected localization of DVT in ilijacofemoral junction in 4,08% patients, although localization of DVT in femoropopliteal region was observed in 6, 12% patients and localization in crural region was in 14.28% patients. Localization of DVT at legs was detected in iliac vein in 16.66% patients, in femoral vein in 25% patients, popliteal vein 8.33% patients, anterior tibial vein 16.66%, posterior tibial vein in 25% and crural veins 8.33% patients. Also we deduced significant difference between two group of patients (chi2 = 10, 76). Such result proves thesis that in most patients with superficial thrombophlebitis and varicose veins is possibility of developing of DVT.
Varicose vein surgery using a pneumatic tourniquet: reduced blood loss and improved cosmesis.
Thompson, J. F.; Royle, G. T.; Farrands, P. A.; Najmaldin, A.; Clifford, P. C.; Webster, J. H.
1990-01-01
A prospective controlled randomised study has been performed of 100 consecutive patients undergoing varicose vein surgery. One group underwent saphenofemoral flush ligation and multiple lower leg avulsions with the leg exsanguinated with a Rhys-Davies cuff, and ischaemia maintained with a pneumatic tourniquet. The other group underwent identical surgery but with a 30 degree head down tilt only. Blood loss was significantly less (13.5 +/- 12 ml vs 133 +/- 78 ml; P less than 0.01) and postopera...
Moon, K H; Dharmarajah, B; Bootun, R; Lim, C S; Lane, Tra; Moore, H M; Sritharan, K; Davies, A H
2017-07-01
Objective Mechanochemical ablation is a novel technique for ablation of varicose veins utilising a rotating catheter and liquid sclerosant. Mechanochemical ablation and radiofrequency ablation have no reported neurological side-effect but the rotating mechanism of mechanochemical ablation may produce microbubbles. Air emboli have been implicated as a cause of cerebrovascular events during ultrasound-guided foam sclerotherapy and microbubbles in the heart during ultrasound-guided foam sclerotherapy have been demonstrated. This study investigated the presence of microbubbles in the right heart during varicose vein ablation by mechanochemical abaltion and radiofrequency abaltion. Methods Patients undergoing great saphenous vein ablation by mechanochemical abaltion or radiofrequency ablation were recruited. During the ablative procedure, the presence of microbubbles was assessed using transthoracic echocardiogram. Offline blinded image quantification was performed using International Consensus Criteria grading guidelines. Results From 32 recruited patients, 28 data sets were analysed. Eleven underwent mechanochemical abaltion and 17 underwent radiofrequency abaltion. There were no neurological complications. In total, 39% (11/28) of patients had grade 1 or 2 microbubbles detected. Thirty-six percent (4/11) of mechanochemical abaltion patients and 29% (5/17) of radiofrequency ablation patients had microbubbles with no significant difference between the groups ( p=0.8065). Conclusion A comparable prevalence of microbubbles between mechanochemical abaltion and radiofrequency ablation both of which are lower than that previously reported for ultrasound-guided foam sclerotherapy suggests that mechanochemical abaltion may not confer the same risk of neurological events as ultrasound-guided foam sclerotherapy for treatment of varicose veins.
[Management of patients with varicose veins presenting with a history of deep venous thrombosis].
Battino, A; Battino, J
1989-01-01
The notion of a history of deep venous thrombosis in patients with varicose veins has often been at the origin of a contemplative attitude toward this pathology. What used to be an act of vigilance has now become plain negligence, if not a therapeutic error. Indeed, the difficulty in diagnosing an acute episode explains the many false positive results obtained; moreover, the variability of the evolution of true venous thrombosis should no longer cause one to adopt a monolithic attitude. In this indication, noninvasive investigating procedures allow distinguishing quite different situations occurring in these patients. In a substantial number of cases, no deep vein circulatory abnormality can be found. Treatment should address primary varicose veins. For those patients with deep venous thrombosis sequelae, such studies allow us to differentiate between occlusion/restriction states from devalvulation, and to detect the precise location of such sequelae, as well as their impact on circulatory function. When occlusion is found, varicose veins, which may be supplementary veins, are left untouched. When devalvulation occurs as an isolated phenomenon, superficial vein insufficiency is of primary importance. Treatment is the more complete that deep reflux will promote relapse through all existing leakage points. If, regardless of this treatment, deep reflux causes significant disturbances, surgical revalvulation should be recommended. More complex cases combining persisting occlusion with devalvulation call for a graded attitude. Noninvasive investigating procedures coupled with phlebography allow us to assess the part played by the various anomalies in causing the disorders.(ABSTRACT TRUNCATED AT 250 WORDS)
Efficacy of varicose vein surgery with preservation of the great safenous vein
Directory of Open Access Journals (Sweden)
Bernardo Cunha Senra Barros
Full Text Available OBJECTIVE: To evaluate the efficacy of surgical treatment of varicose veins with preservation of the great saphenous vein. METHODS: We conducted a prospective study of 15 female patients between 25 and 55 years of age with clinical, etiologic, anatomic and pathophysiologic (CEAP classification 2, 3 and 4. The patients underwent surgical treatment of primary varicose veins with great saphenous vein (GSV preservation. Doppler ultrasonography exams were carried out in the first and third months postoperatively. The form of clinical severity of venous disease, Venous Clinical Severity Score (VCSS was completed before and after surgery. We excluded patients with history of deep vein thrombosis, smoking or postoperatively use of elastic stockings or phlebotonics. RESULTS: All patients had improved VCSS (p <0.001 and reduction in the diameter of the great saphenous vein (p <0.001. There was a relationship between VCSS and the GSV caliber, as well as with preoperative CEAP. There was improvement in CEAP class in nine patients when compared with the preoperative period (p <0.001. CONCLUSION: The varicose vein surgery with preservation of the great saphenous vein had beneficial effects to the GSV itself, with decreasing caliber, and to the symptoms when the vein had maximum caliber of 7.5 mm, correlating directly with the CEAP. The decrease in GSV caliber, even without complete abolition of reflux, leads to clinical improvement by decreasing the reflux volume.
Shingler, Sarah; Robertson, Lindsay; Boghossian, Sheila; Stewart, Marlene
2013-12-09
Compression hosiery or stockings are often the first line of treatment for varicose veins in people without either healed or active venous ulceration. Evidence is required to determine whether the use of compression stockings can effectively manage and treat varicose veins in the early stages. This is an update of a review first published in 2011. To assess the effectiveness of compression stockings for the only and initial treatment of varicose veins in patients without healed or active venous ulceration. For this update the Cochrane Peripheral Vascular Diseases Group Trials Search Co-ordinator searched the Specialised Register (last searched August 2013) and CENTRAL (2013, Issue 5). Randomised controlled trials (RCTs) were included if they involved participants diagnosed with primary trunk varicose veins without healed or active venous ulceration (Clinical, Etiology, Anatomy, Pathophysiology (CEAP) classification C2 to C4). Included trials assessed compression stockings versus no treatment, compression versus placebo stockings, or compression stockings plus drug intervention versus drug intervention alone. Trials comparing different lengths and pressures of stockings were also included. Trials involving other types of treatment for varicose veins (either as a comparator to stockings or as an initial non-randomised treatment), including sclerotherapy and surgery, were excluded. Two authors assessed the trials for inclusion and quality (SS and LR). SS extracted the data, which were checked by LR. Attempts were made to contact trial authors where missing or unclear data were present. Seven studies involving 356 participants with varicose veins without healed or active venous ulceration were included. Different levels of pressure were exerted by the stockings in the studies, ranging from 10 to 50 mmHg. One study assessed compression hosiery versus no compression hosiery. The other six compared different types or pressures of stockings. The methodological quality of
Maldonado-Fernández, Nicolás; Linares-Palomino, Jose Patricio; López-Espada, Cristina; Martínez-Gámez, Francisco Javier; Ros-Díe, Eduardo
2016-03-01
Traditionally, anterior accessory great saphenous vein insufficiency was managed by crossectomy and resection of varicose veins. The aim of this paper is to show the safety and efficacy of a new therapeutic strategy for anterior accessory great saphenous varicose veins. This non-randomised prospective study included 65 patients with varicose veins from the anterior accessory great saphenous vein. The novelty of the technique is to avoid the great saphenous vein crossectomy and perform just flebectomy of the visible veins. Venous duplex studies were performed preoperatively, a month and a year postoperatively. The clinical assessment was done by the Fligelstone scale. The baseline CEAP clinical classification was: 58% C2, 26% C3 and 15% C4-6. The new strategy was applied to all cases. 3 haematomas, 7 cases of asymptomatic partial anterior saphenous thrombosis. Reduction of the initial average diameter was from 6.4 mm anterior saphenous to 3.4 mm by one year (p <0.001). At twelve months a forward flow is maintained in 82% of cases. Recurrence of varicose veins was 8%. All patients improved their clinical status based on the Fligelstone scale. Cases with saphenous diameter bigger than 7.5 mm and obesity were identified as predictors of worse clinical and hemodynamic outcome. This modified surgical strategy for anterior saphenous varicose veins results in better clinical outcomes at one year postoperatively. Copyright © 2015 AEC. Publicado por Elsevier España, S.L.U. All rights reserved.
Power oscillation damping controller
DEFF Research Database (Denmark)
2012-01-01
A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...... signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range....
Chihara, Shingo; Sawada, Kentaro; Tomoeda, Hiroshi; Aoyagi, Shigeaki
2017-02-01
We report a case of pulsatile varicose veins successfully managed by endovenous laser treatment (EVLT) of the great saphenous vein (GSV). A 77-year-old woman taking an anticoagulant was transferred to our hospital for pulsatile varicose veins complicated with repeated venous bleeding from an ulcer of her left lower leg. Doppler echocardiography showed severe tricuspid regurgitation, and duplex ultrasonography revealed an arterial-like pulsating flow in the saphenofemoral junction and along the GSV, but an arteriovenous fistula, obstruction of the deep veins, and the distal incompetent perforators were not detected. Because of a significant bleeding risk due to elevated venous pressure and anticoagulant therapy, EVLT was performed for the GSV, which resulted in the complete occlusion of the GSV and healing of the ulcer. EVLT presents a safe and useful therapeutic technique for pulsatile varicose veins in the limbs. Copyright © 2016 Elsevier Inc. All rights reserved.
Földi, M; Idiazabal, G
2000-12-01
The role of operative management of "symptomatic" varicose veins in patients with lower extremity lymphedema or lipedema is controversial. We reviewed the clinical outcome of 261 patients between 1989-1997 at the Földiclinic with lower extremity lymphedema (68 patients), lipo-lymphedema or lympho-lipedema (103 patients) or lipedema (90 patients) who had undergone operation for varicose veins. In each group, the results were dismal as leg swelling worsened or was unchanged in greater than 90% whereas symptoms such as heaviness, fatigue, cramps (termed varicogenic symptomatology) were improved in less than 10%. These findings support that operations for varicose veins in the legs of patients with lymphedema, lipedema, or combinations of these disorders should be undertaken only if there is an absolute indication present (ascending phlebitis and/or bleeding). Otherwise, complete decongestive physiotherapy is still the best treatment approach for these groups of patients.
Enhancing synchronization in chaotic oscillators by induced heterogeneity
Banerjee, Ranjib; Bera, Bidesh K.; Ghosh, Dibakar; Dana, Syamal Kumar
2017-06-01
We report enhancing of complete synchronization in identical chaotic oscillators when their interaction is mediated by a mismatched oscillator. The identical oscillators now interact indirectly through the intermediate relay oscillator. The induced heterogeneity in the intermediate oscillator plays a constructive role in reducing the critical coupling for a transition to complete synchronization. A common lag synchronization emerges between the mismatched relay oscillator and its neighboring identical oscillators that leads to this enhancing effect. We present examples of one-dimensional open array, a ring, a star network and a two-dimensional lattice of dynamical systems to demonstrate how this enhancing effect occurs. The paradigmatic Rössler oscillator is used as a dynamical unit, in our numerical experiment, for different networks to reveal the enhancing phenomenon.
Hermanns, H-J
2008-08-01
The combination of varicose vein disease and obesity is common in clinical practice. Long operations, high blood loss and extensive bruises are the results. Since 2005, a new roll-on cuff for varicose vein surgery with a thigh circumference of 90 cm is available (big cuff). Between 1.4.1995 and 31.3.2006, surgeons at the Clinic for Vascular Medicine, Venous and Wound Care Centre Krefeld carried out varicose vein surgery in 10 054 cases. 92% (n=9,249) of the operations were done with a roll-on cuff tourniquet. The cuff was inflated to 120 mmHg and rolled up to the thigh of the leg. We present the results of the "big cuff" pilot-study and our general experience with varicose vein surgery in bloodless technique. 1) Big Cuff: A transducer was located between cuff and the skin. A cuff pressure of 120 mmHg and a median thigh circumference of 79.5 cm led to a median pressure of 218.6 mmHg. The tourniquet time was 35 minutes and the systolic blood pressure during the operation did not exceed 120 mmHg. Under these conditions we did not encounter any problems. 2) Bloodless limb technique: 9 249 of our own operations using the Boazul cuff were analysed. We did not find any major complications such as acute arterial occlusion or deep vein thrombosis (DVT) during the procedure. At present the DVT rate amounts to 0.05 %. The use of the bloodless limb technique for varicose vein surgery is very comfortable, especially in cases of severe varicose veins and obesity. Maintenance of operation standards and utmost care of the cuffs lead to the successful use of this procedure.
YouTube as a source of patient information for varicose vein treatment options.
Kwok, Trevor M Y; Singla, Animesh A; Phang, Kevin; Lau, Annie Y S
2017-03-01
The purpose of this study was to analyze the quality of content and potential sources of bias in videos available on YouTube pertaining to interventional treatment for varicose veins. Searches were performed on YouTube to identify videos pertaining to interventional treatment for varicose veins. Videos that met eligibility criteria were analyzed and rated according to predetermined criteria by two independent assessors, with a third independent assessor to resolve any discrepancy. Each video was rated for its informational quality (good, fair, poor) and stance (for, neutral, against, unclear) toward the treatment option discussed. A total of 284 videos were extracted, of which 228 met eligibility criteria and were analyzed. The largest group of videos (47.3%) received a quality rating of fair, meaning that they discussed one or two aspects of a treatment option, such as procedural technique and indications. Among those videos rated poor (25.0%), nearly all videos (98.2%) failed to mention a specific treatment. Most videos (71.1%) were in favor of the treatment discussed without presenting balanced discussion of alternatives. Private companies represented the most frequent source of videos analyzed (73.2%). There was a statistically significant correlation between quality and video source (χ 2 = 9.308; df = 2; P = .010), with videos from private companies generally receiving poorer quality ratings than other videos. There was no association between quality and viewing frequency of videos (P = .379). On the whole, the videos available on YouTube are neither sufficiently comprehensive nor adequately balanced to be recommended as patient education material regarding interventional treatment options for varicose veins. Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
M. Mahbobi; M. Ghorbani; Z. Beheshti; AA. Haghdoost; H. Sharif Nia
2010-01-01
Background and aims varicose of lower limbs is one of the most common injuries which is caused and intensified by the job activities through passing the time and can cause the person and the society to bear the high cost. This study has been done in order to investigate the relationship between the demographic and occupational factors with the lower limb varicose severity of the nurses in Amol hospital. Methods This cross-sectional study was conducted through on 203 nurses in Amol h...
Rastel, D
2014-12-01
Compression stockings are the major long-term treatment of non-complicated primary varicose veins recommended by international consensus. Nevertheless there are few data concerning the patient compliance to treatment. Hundred and forty-four patients with varicose veins of primary origin were prospectively recruited and questioned about their compression therapy: 29.2% patients are wearing compression stockings, and for 10.4% on a daily basis; 32.6% do not wear their compression mainly because it is not well tolerated; 38.2% do not have compression treatment because it is not recommended or not prescribed by the physician. Copyright © 2014 Elsevier Masson SAS. All rights reserved.
International Nuclear Information System (INIS)
Zhu Yongqiang; Xu Jingxuan; Chen Junying; Wu Yan; Zhang Chuanhong; Li Liang
2012-01-01
Objective: To assess the clinical efficacy of foam sclerotherapy with lauromacrogol for varicose veins of the lower extremities. Methods: During the period from February to July 2011, we retrospectively analyzed 20 patients with varicose veins of the lower extremities, who were treated with lauromacrogol foam sclerosing agent injected directly at varicose veins, and in 5 extremities injected at the great saphenous vein (GSV) through a catheter at the same time. Elastic bandages were applied at the site of the injected varicosities after the therapy. The clogging of the varicose veins, the improvement of the clinical symptoms and the adverse reaction were observed. Results: Lauromacrogol foam sclerosing agent was successfully injected under the guidance of fluoroscopy in 20 patients with 28 affected extremities. The average volume of foam sclerosing agent in each affected extremity was 7.8 ml. All patients presented self limiting minor complications, including swelling and pain, which was obviously alleviated by the externally applied Mucopolysaccharide Polysulfate Cream. Two patients presented cough that was relieved after inhaling oxygen. Most of treated varicosities demonstrated pigmentation after the first week, which gradually disappeared after the four-month use of vitamin E capsule. A second foam sclerotherapy was carried out for 3 affected extremities of 3 patients two months after the first therapy. Two cases of leg venous ulcer were healed within a few weeks. All patients could walk immediately with no deep vein thrombosis, pulmonary embolism, anaphylaxis, or transient visual disturbance. Obvious abnormal varicose veins as well as the soreness and fatigue of the lower extremities disappeared in all patients at the 10th-month follow-up. The grading of the disease was significantly improved by the treatment (Z=5.103, P<0.01). Conclusions: The efficacy of lauromacrogol foam sclerosing agent in the treatment of varicose veins of the lower extremities is
International Nuclear Information System (INIS)
Akhiezer, A.I.; Davydov, L.N.; Spol'nik, Z.A.
1976-01-01
Oscillations of a nonideal crystal are studied, in which macroscopic defects (pores) form a hyperlattice. It is shown that alongside with acoustic and optical phonons (relative to the hyperlattice), in such a crystal oscillations of the third type are possible which are a hydridization of sound oscillations of atoms and surface oscillations of a pore. Oscillation spectra of all three types were obtained
Energy Technology Data Exchange (ETDEWEB)
Straasø, Lasse Arnt; Nielsen, Jakob Toudahl; Bjerring, Morten; Nielsen, Niels Chr., E-mail: ncn@inano.au.dk [Center for Insoluble Protein Structures (inSPIN), Interdisciplinary Nanoscience Center (iNANO) and Department of Chemistry, Aarhus University, DK-8000 Aarhus C (Denmark); Khaneja, Navin [Division of Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States)
2014-09-21
Application of sets of {sup 13}C-{sup 13}C internuclear distance restraints constitutes a typical key element in determining the structure of peptides and proteins by magic-angle-spinning solid-state NMR spectroscopy. Accurate measurements of the structurally highly important {sup 13}C-{sup 13}C distances in uniformly {sup 13}C-labeled peptides and proteins, however, pose a big challenge due to the problem of dipolar truncation. Here, we present novel two-dimensional (2D) solid-state NMR experiments capable of extracting distances between carbonyl ({sup 13}C′) and aliphatic ({sup 13}C{sub aliphatic}) spins with high accuracy. The method is based on an improved version of the four-oscillating field (FOLD) technique [L. A. Straasø, M. Bjerring, N. Khaneja, and N. C. Nielsen, J. Chem. Phys. 130, 225103 (2009)] which circumvents the problem of dipolar truncation, thereby offering a base for accurate extraction of internuclear distances in many-spin systems. The ability to extract reliable accurate distances is demonstrated using one- and two-dimensional variants of the FOLD experiment on uniformly {sup 13}C,{sup 15}N-labeled-L-isoleucine. In a more challenging biological application, FOLD 2D experiments are used to determine a large number of {sup 13}C′-{sup 13}C{sub aliphatic} distances in amyloid fibrils formed by the SNNFGAILSS fibrillating core of the human islet amyloid polypeptide with uniform {sup 13}C,{sup 15}N-labeling on the FGAIL fragment.
Oscillators - a simple introduction
DEFF Research Database (Denmark)
Lindberg, Erik
2013-01-01
Oscillators are kernel components of electrical and electronic circuits. Discussion of history, mechanisms and design based on Barkhausens observation. Discussion of a Wien Bridge oscillator based on the question: Why does this circuit oscillate ?......Oscillators are kernel components of electrical and electronic circuits. Discussion of history, mechanisms and design based on Barkhausens observation. Discussion of a Wien Bridge oscillator based on the question: Why does this circuit oscillate ?...
Operations for hernia and varicose veins in a day-bed unit.
Goulbourne, I A; Ruckley, C V
1979-01-01
Over eight years (1970-8) 1055 patients underwent operations for hernia or "major" varicose veins in a day-bed unit. Here, 608 were discharged home on the day of operation, 262 were transferred to a convalescent hospital for 48 hours, and 161 were retained in the acute ward as part of a controlled trial. Special emphasis was placed on selection and preadmission screening. Failure of planning was uncommon in that only 2.5% were detained in hospital and 1% had to be readmitted. About one-quarter of the patients had complications but these were generally trivial and were satisfactorily treated by the community nursing sisters or general practitioners, or both. Analysis of the total operations for hernia or varicose veins in the unit over the past 19 years shows that, whereas formerly all patients with these conditions were admitted to the main surgical ward, nowadays almost all are managed either by day care or in a five-day ward. PMID:509075
Oscillating Permanent Magnets.
Michaelis, M. M.; Haines, C. M.
1989-01-01
Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)
Disselhoff, B. C. V. M.; Buskens, E.; Kelder, J. C.; Kinderen, D. J. der; Moll, F. L.
Background: Although endovenous laser ablation for varicose veins is replacing surgical stripping, proper economic evaluation with adequate follow-up in a randomised clinical trial is important for considered policy decisions regarding the implementation of new techniques. Methods: Data from a
Fernando, Ruchira S W; Muthu, Carl
2014-08-01
To assess the effectiveness of adopting endovenous laser treatment (EVLT) as the primary treatment modality for varicose veins at Auckland City Hospital (Auckland, New Zealand). The outcomes of 354 consecutive EVLT procedures performed between 2007 and 2013 were reviewed. Data was collected from a prospectively maintained procedural database and by retrospective chart review. Of the 319 patients who had an ultrasound, at 1 month post-procedure there was a saphenous vein occlusion rate of 96%. Side effects were minimal with no cases of DVT or skin burns and one case of self-limiting neuralgia. The procedure was well tolerated with a median pain score of 3. Since the adoption of EVLT there has been a large increase in the number of patients treated for varicose veins (28 in 2007 compared to 176 in 2013). EVLT is a safe and effective treatment for varicose veins and its adoption has allowed a large increase in the number of varicose vein patients treated at Auckland City Hospital.
Gibson, Kathleen; Minjarez, Renee; Ferris, Brian; Neradilek, Moni; Wise, Matthew; Stoughton, Julianne; Meissner, Mark
2017-07-01
Pelvic venous incompetence can cause symptomatic varicose veins in the perineum, buttock, and thigh. Presentation, symptom severity, and response to treatment of pelvic source varicose veins are not well defined. Currently available tools to measure the severity of lower extremity venous disease and its effects on quality of life may be inadequate to assess disease severity in these patients. The purpose of this study was to evaluate the histories, demographics, and clinical presentations of women with pelvic source varicose veins and to compare these data to a population of women with nonpelvic source varicose veins. A total of 72 female patients with symptomatic pelvic source varicose veins were prospectively followed up. Age, weight, height, parity, and birth weights of offspring were recorded. Both pelvic source varicose veins and saphenous incompetence were identified by duplex ultrasound. Patients were queried as to their primary symptoms, activities that made their symptoms worse, and time when their symptoms were most prominent. Severity of disease was objectively evaluated using the revised Venous Clinical Severity Score (rVCSS) and 10-point numeric pain rating scale (NPRS). Compared with women without a pelvic source of varicose veins (N = 1163), patients with pelvic source varicose veins were younger (mean, 44.6 ± 8.6 vs 52.6 ± 12.9 years; P source varicose veins are a unique subset of patients. They are younger and thinner than those with nonpelvic source varicose veins, have larger infants than the general U.S. population, and have an inverse correlation between age and pain. As the majority of premenopausal patients have increased symptoms during menses, this may be due to hormonal influence. As it is poorly associated with patient-reported discomfort, the rVCSS is a poor tool for evaluating pelvic source varicose veins. A disease-specific tool for the evaluation of pelvic source varicose veins is critically needed, and this study is a first
Chan, Chih-Yang; Chen, Tzu-Chun; Hsieh, Yung-Kun; Huang, Jih-Hsin
2011-07-01
The purpose of the present study was to compare management of varicose veins by endovenous laser ablation (EVL) and a vein-sparing procedure (CHIVA: Conservatrice et Hémodynamique de l'Insuffisance Veineuse en Ambulatoire) for management of varicose veins. Data from 82 consecutive patients with great saphenous vein (GSV) reflux and primary varicose veins presenting to the vascular clinic at the Far Eastern Memorial Hospital between June and December 2005 were reviewed. Of these, 74 who met the inclusion criteria were included in this study. CHIVA was performed by a double division of the refluxing saphenous vein (i.e., proximal and distal ligation), and EVL was performed using 10-14 W beginning approximately 4 cm below the saphenofemoral junction to the level of the knee. Phlebectomy for significant branch varicose veins on the leg was routinely performed in all patients. Outcome measures included postoperative thrombophlebitis, bruising, pain, assessment of ultrasonographic and clinical symptoms (measured by the Venous Clinical Severity Score [VCSS]) and comparison of quality of life survey scores obtained preoperatively and postoperatively (measured by the Aberdeen Varicose Veins Score [AVVQ] and RAND-36). Patients were examined one week post-procedurally and again at 1, 3, 6, and 12 months. Endovenous laser ablation and CHIVA were performed on 54 and 20 patients, respectively. The EVL patients had significantly higher pain scores and bruising than the CHIVA group (pEVL and CHIVA; however, patients treated by EVL had significantly more pain postoperatively than those treated by CHIVA (p=0.003). Twenty-two of 54 (40.7%) and 3 of 17 (17.6%) patients in the EVL and CHIVA groups, respectively, required sclerotherapy for residual varicosities (p=0.026). Both groups benefited significantly from surgery in disease-specific perceptions. The CHIVA patients had less pain postoperatively and a significantly higher sclerotherapy-free period compared to patients in the EVL
Directory of Open Access Journals (Sweden)
Shaik Ahmad
2016-03-01
Full Text Available BACKGROUND Varicose veins affect at least 1 out of 5 in the world and the cost of health care for the society is significant. In a developing country like India, study encompassing the clinical evaluation and management of lower limb varicose veins on the conventional lines seems a necessity to improve the quality care with the available resources. OBJECTIVES To study the relation between site of incompetence and complications, pattern of complications, surgical management and its outcome for lower limb varicose veins. METHODS A total 26 number of patients with primary varicose veins admitted, investigated, operated and followed up. Final outcome evaluated. All the information was taken down in the proforma, designed for the study. RESULTS In the study, it was noted that the varicose veins affect younger, adult, and middle age population. (20 to 60 years. Majority of the patients were male (84.60%. Perforator incompetence only = 42.3% (n=11. Perforator incompetence + saphenofemoral/saphenopopliteal incompetence seen in 57.7%. Long saphenous vein involvement was seen in 90.5% of the patients and both LSV and SSV involvement in 9.5%. A greater portion of the patients had combined valvular incompetence (69.56%. The mean ulcer healing time in our study was 2.8 weeks following surgery (90%. Residual incompetent perforators are seen in 7.6% (n=2. New incompetent perforators seen in 7.6% (n=2. Postoperative wound infection of the incision of SPJ ligation was seen in 3.8% (n=1 of the patients, but not the SEPS wound infection and the total complication rate was 3.85%. The mean postoperative stay for patients undergoing SEPS procedure alone was 3.6 days. The mean postoperative stay for patients who underwent perforator ligation with concomitant stripping procedure was 5 days. INTERPRETATION AND CONCLUSION Majority of the patients present with complications of varicose vein with combined valvular incompetence and surgical treatment with stripping of path
Rabi oscillations in bidimensional photonic crystals
International Nuclear Information System (INIS)
Centeno, E.; Felbacq, D.
2000-01-01
We theoretically and numerically investigate transient phenomena in finite two-dimensional photonic crystals doped by single-mode microcavities. We show that for antisymmetric defect modes, there are Rabi oscillations between the microcavities. We develop a spectral analysis which permits us to compute the Rabi frequencies of these oscillations as well as the Q factor of the microcavities. We present a method allowing the computation of the coupling factor between localized modes
Damping of Crank–Nicolson error oscillations
DEFF Research Database (Denmark)
Britz, Dieter; Østerby, Ole; Strutwolf, J.
2003-01-01
The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one...... be computationally more expensive with some systems. The simple device of starting with one backward implicit (BI, or Laasonen) step does damp the oscillations, but not always sufficiently. For electrochemical microdisk simulations which are two-dimensional in space and using CN, the use of a first BI step is much...
Commensurability oscillations in a periodically modulated phosphorene
Tahir, M.; Vasilopoulos, P.
2017-10-01
The recent experimental realization of high-quality phosphorene leads to novel electronic and optical properties with possible new device applications due to its huge direct band gap. We study the commensurability or Weiss oscillations in monolayer phosphorene in the presence of a weak perpendicular magnetic field B and a weak and periodic, electric or magnetic one-dimensional modulation. Either modulation broadens the Landau levels into bands, whose width oscillates with B, and the oscillations appear in the electrical conductivity perpendicular to the modulation taken along the direction (x) of the smaller effective mass. Compared with the oscillations of the diffusive conductivity in a two-dimensional electron gas (2DEG) for typical electron densities n_e˜1015~m-2 , the ones in phosphorene, with typical n_e˜1016~m-2 , have approximately similar height but a period significantly smaller when plotted versus 1/B while plotted versus B they occur at significantly higher fields. The Shubnikov-de Haas oscillations exhibit a similar behaviour. When the modulation is taken along the direction (y) of the larger effective mass, the oscillation period is close to that of a 2DEG. For equal modulation strengths the bandwidth due to a magnetic modulation is one order of magnitude larger than that due to an electric one and the amplitude of the oscillations in the diffusive conductivity about 50 times larger. Numerical results are presented for experimentally relevant parameters.
Lee, Amanda J; Robertson, Lindsay A; Boghossian, Sheila M; Allan, Paul L; Ruckley, C Vaughan; Fowkes, F Gerald R; Evans, Christine J
2015-01-01
The natural history in the general population of chronic venous disease in the legs is not well understood. This has limited our ability to predict which patients will deteriorate and to assign clinical priorities. The aims of this study were to describe the progression of trunk varicose veins and chronic venous insufficiency (CVI) in the general population, to identify important lifestyle and clinical prognostic factors, and to determine the relationship between venous reflux and progression. The Edinburgh Vein Study is a population-based cohort study in which randomly selected adults aged 18 to 64 years had an examination at baseline. This included a questionnaire on lifestyle and clinical factors, standardized assessment and classification of venous disease in the legs, and duplex scan to detect venous reflux in eight segments of each leg. A follow-up examination 13 years later included a reclassification of venous disease to ascertain progression in the development or increase in severity of varicose veins and CVI. Among 1566 adults seen at baseline, 880 had a follow-up examination, of whom 334 had trunk varicose veins or CVI at baseline and composed the study sample. The mean (standard deviation) duration of follow-up was 13.4 (0.4) years. Progression was found in 193 (57.8%), equivalent to 4.3% (95% confidence interval [CI], 3.7-4.9) annually. In 270 subjects with only varicose veins at baseline, 86 (31.9%) developed CVI, with the rate increasing consistently with age (P = .04). Almost all subjects (98%) with both varicose veins and CVI at baseline deteriorated. Progression of chronic venous disease did not differ by gender or leg, but a family history of varicose veins and history of deep venous thrombosis increased risk (odds ratio [OR], 1.85 [95% CI, 1.14-1.30] and 4.10 [95% CI, 1.07-15.71], respectively). Overweight was associated with increased risk of CVI in those with varicose veins (OR, 1.85; 95% CI, 1.10-3.12). Reflux in the superficial system
Economic aspects of day care after operations for hernia or varicose veins.
Prescott, R J; Cutherbertson, C; Fenwick, N; Garraway, W M; Ruckley, C V
1978-09-01
In a trial of 360 patients with hernia or varicose veins, day care surgery provided an economic alternative to the provision of surgical aftercare either in the surgical wards of a district hospital or in a convalescent hospital. There was only slightly more work for general practitioners. Most of the additional work for the community services was carried out by district nurses, with an average contact time in the postoperative period of 325 minutes for day care patients, compared with 186 minutes and 204 minutes respectively for patients admitted for 48 hours to the surgical or convalescent wards. Day care produced estimated savings of 30 pounds compared with the costs of a 48-hour stay in the surgical wards, and savings of 22 pounds compared with a 48-hour stay in the convalescent wards.
International Nuclear Information System (INIS)
Firsov, E.F.; Gladkikh, V.G.; Lazarenko, V.A.; Shevelev, E.L.; Pashin, S.V.
1995-01-01
Analysis of clinical data and results of retrograde femoral and popliteal phlebographics in 108 patients with varicose disease of the lower limbs permitted the authors to propose a three-stage classification of valvular insufficiency of the deep veins and to demonstrate that the disease compensation stages are related to the presence and degree of retrograde blood flow. Analysis of retrograde phlebograms helped single out 8 variants of retrograde blood flow in the deep femoral veins and 12 variants in the deep veins of the shin with valvular insufficiency thereof, which is practically important for interpretation of x-ray findings and for the choice of the optimal method and volume of surgical correction of this vascular abnormality. 4 refs.; 5 figs
[Early results after varicose vein surgery--a multicenter patient inquiry].
Hermanns, H-J
2008-08-01
Beside varicose vein surgery, endovenous procedures (endovenous laser therapy, VNUS and foam sclerotherapy) are now therapeutic options with the following advantages: low invasiveness, only out-patient operations, quick resumption of general activities. Whether or not classical vein surgery today still fulfills patient demands was analysed by a study group of German vascular surgeons (ANG) as a multicentre patient questioning. The questionnaire was subdivided into eight main complexes with 24 questions about the early results of stripping operations (from start of preparation until suture removal) and the patients answers were analysed. Answers with points (1-6) and free answers were possible. Between 1.1.2005 and 31.3.2005 18 centres for vascular surgery collected 1708 questionnaires from patients after stripping operations. The complex "preparation and information about the operation" was scored with 1.33 to 1.39. The "general organisation" of the vascular centre was scored between 1.22 and 1.30. "Pain after operation" was rated at 1.98 (immediately), 2.26 (first day) and 2.12 (third day after operation). Reasons for other problems after surgery were haematoma (3.09), problems with the compression dressing (1.67), circulatory collapse (1.51), headache (1.33), nausea (1.25). The total score for all centres was 1.47. The early results after varicose vein surgery are good up to very good. The patients' reconvalescence time is short and there is a quick resumption of general activities. The invasiveness of vein surgery seems to be overestimated. Comparative studies to evaluate the new methods are necessary. Benchmarking projects like this study are essential parts of current quality control systems.
What are the symptoms of varicose veins? Edinburgh vein study cross sectional population survey
Bradbury, Andrew; Evans, Christine; Allan, Paul; Lee, Amanda; Ruckley, C Vaughan; Fowkes, F G R
1999-01-01
Objective To define the relations between age, sex, lower limb symptoms, and the presence of trunk varicose veins on clinical examination. Design Cross sectional population study. Setting 12 general practices with catchment areas geographically and socioeconomically distributed throughout Edinburgh. Participants An age stratified random sample of 1566 people (699 men and 867 women) aged 18-64 selected from the computerised age-sex registers of participating practices. Main outcome measures Self administered questionnaire on the presence of lower limb symptoms and physical examination to determine the presence and severity of varicose veins. Results Women were significantly more likely than men to report lower limb symptoms such as heaviness or tension, swelling, aching, restless legs, cramps, and itching. The prevalence of symptoms tended to increase with age in both sexes. In men, only itching was significantly related to the presence and severity of trunk varices (linear test for trend, P=0.011). In women there was a significant relation between trunk varices and the symptoms of heaviness or tension (P⩽0.001), aching (P⩽0.001), and itching (P⩽0.005). However, the level of agreement between the presence of symptoms and trunk varices was too low to be of clinical value, especially in men. Conclusions Even in the presence of trunk varices, most lower limb symptoms probably have a non-venous cause. Surgical extirpation of trunk varices is unlikely to ameliorate such symptoms in most patients. Key messagesIn this population survey women were more likely than men to report a wide range of lower limb symptomsIn men, only itching was significantly related to the presence of trunk varicesIn women there was a significant relation between trunk varices and heaviness or tension, aching, and itchingThe level of agreement between the presence of symptoms and trunk varices is probably too low to be clinically usefulA thorough clinical history and examination should be
Recurrent varicose veins of the legs. Analysis of a social problem.
Cardia, G; Catalano, G; Rosafio, I; Granatiero, M; De Fazio, M
2012-01-01
The present study was aimed at assessing the experience of a single referral center with recurrent varicose veins of the legs (RVL) over the period 1993-2008. Among a total of 846 procedures for Leg Varices (LV), 74 procedures were for RVL (8.7%). The causes of recurrence were classified as classic: insufficient crossectomy (13); incompetent perforating veins (13); reticular phlebectasia (22); small saphenous vein insufficiency (9); accessory saphenous veins (4); and particular: post-hemodynamic treatment (5); incomplete stripping (1); Sapheno-Femoral Junction (SFJ) vascularization (5); post-thermal ablation (2). For the "classic" RVL the treatment consisted essentially of completing the previous treatment, both if the problem was linked to an insufficient earlier treatment and if it was due to a later onset. The most common cause in our series was reticular phlebectasia; when the simple sclerosing injections are not sufficient, this was treated by phlebectomy according to Mueller. The "particular" cases classified as 1, 2 and 4 were also treated by completing the traditional stripping procedure (+ crossectomy if this had not been done previously), considered to be the gold standard. In the presence of a SFJ neo-vascularization, with or without cavernoma, approximately 5 cm of femoral vein were explored, the afferent vessels ligated and, if cavernoma was present, it was removed. Although inguinal neo-angiogenesis is a possible mechanism, some doubt can be raised as to its importance as a primary factor in causing recurrent varicose veins, rather than their being due to a preexisting vein left in situ because it was ignored, regarded as insignificant, or poorly evident. In conclusion, we stress that LV is a progressive disease, so the treatment is unlikely to be confined to a single procedure. It is important to plan adequate monitoring during follow-up, and to be ready to reoperate when new problems present that, if left, could lead the patient to doubt the
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Lim, C S; Gohel, M S; Shepherd, A C; Davies, A H
2010-08-01
This study aimed to assess the trends and regional variations in secondary care treatment of patients with varicose veins in National Health Service (NHS) England based on data published by the Hospital Episode Statistics which was freely and readily available to the public and health-care policy-makers. Hospital Episode Statistics data for patients being treated for varicose veins, and UK Statistics Authority population estimates in all 28 Strategic Health Authorities (SHAs) in England from 2002 to 2006 were retrieved and analysed. Between 2002 and 2006 there was a 20% overall reduction (46,190-37,135) in the total number of varicose vein procedures performed in NHS England per year. The number of varicose vein procedures performed per 100,000 population per year varied significantly across the SHAs (P SHAs. The annual proportion of varicose vein procedures performed as daycases had increased from 56% to 64% during the period. From 2002 to 2006 there was an overall reduction in the total number of varicose vein procedures performed in NHS England with major regional variations.
Directory of Open Access Journals (Sweden)
Tsarev О.А.
2015-12-01
Full Text Available Aim: to identify the phenotypic characteristics of indeterminate connective tissue dysplasia, which help to predict the progression of varicose veins of lower extremities and disease recurrence after surgery. Material and Methods. The long-term results of surgical treatment of 60 patients with varicose veins of lower extremities in a 5-year period after phlebectomy were analyzed. The phenotypic characteristics of indeterminate connective tissue dysplasia were researched. 24 patients had recurrence of varicose veins of lower extremities associated with disease progression; 36 patients did not have recurrence of varicose veins of lower extremities. Results. All the patients demonstrated the signs of indeterminate connective tissue dysplasia, whereas their frequency was different. There were specified nine phenotypic characteristics of indeterminate connective tissue dysplasia, which were significantly more frequent for patients with recurrence of varicose vein disease of lower extremities: 1 postural abnormality, 2 flat foot, 3 skin pallor, 4 hyperextension of skin, 5 positive "wrist test", 6 positive "pollex test", 7 diastasis recti abdominis, 8 myopia, 9 hematomas which form quickly. Conclusion. The determined sum of phenotypic characters of indeterminate connective tissue dysplasia allows to predict progression of varicose vein disease of lower extremities, and offers new opportunities for improving the results of surgical treatment via developing special therapeutic measures aimed at improving lifestyle and dysplasia treatment.
Neutrino oscillations in deconstructed dimensions
International Nuclear Information System (INIS)
Haellgren, Tomas; Ohlsson, Tommy; Seidl, Gerhart
2005-01-01
We present a model for neutrino oscillations in the presence of a deconstructed non-gravitational large extra dimension compactified on the boundary of a two-dimensional disk. In the deconstructed phase, sub-mm lattice spacings are generated from the hierarchy of energy scales between ∼ 1 TeV and the usual B-L breaking scale ∼ 10 15 GeV. Here, short-distance cutoffs down to ∼ 1 eV are motivated by the strong coupling behavior of gravity in local discrete extra dimensions. This could make it possible to probe the discretization of extra dimensions and non-trivial field configurations in theory spaces which have only a few sites, i.e., for coarse latticizations. Thus, the model has relevance to present and future precision neutrino oscillation experiments. (author)
Vakhitov, M Kh; Bol'shakov, O P
2011-01-01
In order to reveal anatomical prerequisites for the development of primary varicose veins we investigated the structure of the venous system on a total of 53 adult human cadaveric lower extremities. Congenital morphological grounds providing the phlebohaemodynemics of the lower limbs are ambiguous in different individual forms. We revealed a total of 18 variants of the structure of deep veins, reflecting various stages of the embryonic development. In 34.1% of cases we saw the forms characteristic of incomplete reduction and unfinished transformation, with 30.2% of cases showing the utmost degree of reduction and transformation. An inadequate outflow along the deep veins conditioned by their anatomical structure is a prerequisite for the development of valvular insufficiency and venous reflux to the superficial veins followed by varicose transformation thereof
Belardi, P; Lucertini, G
1994-12-01
Re-exploration of the sapheno-femoral junction for recurrent varicose veins presents many problems. The lateral approach to the sapheno-femoral junction via a groin incision as previously described was performed in 109 lower limbs. The operative mortality rate was 0%. Functional outcome was good in 106 cases (97.2%) and only in three (2.8%) did recurrent varicose veins occur in the upper thigh. Complications were mainly lymphorrhoea (six cases, 5.5%). Cosmetic results were also satisfactory. This surgical procedure allows an easy and safe approach to the sapheno-femoral junction and avoids damage to femoral vessels. Recurrence was rare and caused by incompetent communicating veins in the upper thigh. These characteristics make the lateral approach the preferred technique for re-exploration of the sapheno-femoral junction.
Ma, Hongbin
2015-01-01
This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation, theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary factors affecting oscillating motions and heat transfer, neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes. The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...
Phenomenology of neutrino oscillations
Indian Academy of Sciences (India)
Abstract. The phenomenology of solar, atmospheric, supernova and laboratory neutrino oscillations is described. Analytical formulae for matter effects are reviewed. The results from oscillations are confronted with neutrinoless double beta decay.
Baseline-dependent neutrino oscillations in asymmetrically-warped spacetimes
Hollenberg, S; Pas, H; Weiler, J T
2010-01-01
We study the possibility to explain the LSND anomaly by means of resonant active-sterile neutrino oscillations in an asymmetrically-warped spacetime. In such extra-dimensional scenarios sterile neutrinos take shortcuts through the extra dimension, which results in new types of resonances in the oscillation probability.
Monitoring the Madden-Julian oscillation with geopotential height
Leung, Jeremy Cheuk-Hin; Qian, Weihong
2017-09-01
This paper examines the three-dimensional geopotential height structure of the Madden-Julian oscillation (MJO) and proposes that the MJO convection signals can be well reflected by upper-tropospheric zonal anomalous height gradient (ZAHG, \
The colpitts oscillator family
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
A tutorial study of the Colpitts oscillator family defined as all oscillators based on a nonlinear amplifier and a three- terminal linear resonance circuit with one coil and two capacitors. The original patents are investigated. The eigenvalues of the linearized Jacobian for oscillators based...
Directory of Open Access Journals (Sweden)
Derya Atik
2016-01-01
Full Text Available Aim. We aimed to determine the effect of external apple vinegar application on the symptoms and social appearance anxiety of varicosity patients who were suggested conservative treatment. Method. The study was planned as an experimental, randomized, and controlled study. 120 patients were randomly selected and then were randomly allocated to either experimental or control group by simple blind random sampling method. In the collection of research data, a questionnaire questioning sociodemographic and clinical characteristics, the Visual Analog Scale (VAS for pain, and the Social Appearance Anxiety Scale (SAAS were used. The patients in the study group were suggested to apply apple vinegar to the area of the leg with varicosity alongside the treatment suggested by the doctor. The patients in the control group received no intervention during the study. Results. The sociodemographic and clinic characteristics of both groups were found to be similar (p>0.05. The patients were evaluated with regard to cramps, pain, leg fatigue perception, edema, itching, pigmentation, and weight feelings in the leg, VAS, and SAAS averages in the second evaluation; the control group had a decrease in such symptoms (p>0.05 although the decrease in the application group was higher and statistically meaningful (p<0.05. Conclusion. We determined that the external application of apple vinegar on varicosity patients, which is a very easy application, increased the positive effects of conservative treatment.
Tang, T Y; Kam, J W; Gaunt, M E
2017-02-01
Objectives This study assessed the effectiveness and patient experience of the ClariVein® endovenous occlusion catheter for varicose veins from a large single-centre series in the UK. Methods A total of 300 patients (371 legs) underwent ClariVein® treatment for their varicose veins; 184 for great saphenous vein (GSV) incompetence, 62 bilateral GSV, 23 short saphenous vein (SSV), 6 bilateral SSV and 25 combined unilateral great saphenous vein and SSV. Patients were reviewed at an interval of two months post procedure and underwent Duplex ultrasound assessment. Postoperative complications were recorded along with patient satisfaction. Results All 393 procedures were completed successfully under local anaesthetic. Complete occlusion of the treated vein was initially achieved in all the patients, but at eight weeks' follow-up, there was only partial obliteration in 13/393 (3.3%) veins. These were all successfully treated with ultrasound-guided foam sclerotherapy. Procedures were well tolerated with a mean pain score of 0.8 (0-10). No significant complications were reported. Conclusions ClariVein® can be used to ablate long and short saphenous varicose veins on a walk-in-walk-out basis. Bilateral procedures can be successfully performed, and these are well tolerated as can multiple veins in the same leg. Early results are promising but further evaluation and longer term follow-up are required.
Broadband hyperchaotic oscillator with delay line
DEFF Research Database (Denmark)
Cenys, Antanas; Lindberg, Erik; Anagnostopoulos, A. N.
2002-01-01
Dynamical systems with time delay can be employed as high dimensional hyperchaotic oscillators with multiple positive Lyapunov exponents. We describe an electronic circuit composed of a 3-stage amplifier and a delay line in the feedback loop. The 1st stage of the amplifier is a nonlinear one while...
Polymerization and oscillation stuttering in a filamentous model of the subcellular Min oscillation
Rutenberg, Andrew; Sengupta, Supratim; Sain, Anirban; Derr, Julien
2011-03-01
We present a computational model of the E. coli Min oscillation that involves polymerization of MinD filaments followed by depolymerization stimulated by filament-end zones of MinE. Our stochastic model is fully three-dimensional, and tracks the diffusion and interactions of every MinD and MinE molecule. We recover self-organized Min oscillations. We investigate the experimental phenomenon of oscillation stuttering, which we relate to the disruption of MinE tip-binding at the filament scale.
Gyroscope with two-dimensional optomechanical mirror
Davuluri, Sankar; Li, Kai; Li, Yong
2017-11-01
We propose an application of two-dimensional optomechanical oscillator as a gyroscope by detecting the Coriolis force which is modulated at the natural frequency of the optomechanical oscillator. Dependence of gyroscope's sensitivity on shot noise, back-action noise, thermal noise, and input laser power is studied. At optimal input laser power, the gyroscope's sensitivity can be improved by increasing the mass or by decreasing the temperature and decay rate of the mechanical oscillator. When the mechanical oscillator's thermal occupation number, n th, is zero, sensitivity improves with decrease in frequency of the mechanical oscillator. For {n}{{th}}\\gg 1, the sensitivity is independent of the mechanical oscillator's frequency.
Nature's Autonomous Oscillators
Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.
2012-01-01
Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.
A case-control study of risk factors of chronic venous ulceration in patients with varicose veins.
Abelyan, Gohar; Abrahamyan, Lusine; Yenokyan, Gayane
2018-02-01
Background/objectives Venous ulcers carry psychological and high financial burden for patients, causing depression, pain, and limitation of mobility. The study aimed to identify factors associated with an increased risk of venous ulceration in patients with varicose veins in Armenia. Methods A case-control study design was utilized enrolling 80 patients in each group, who underwent varicose treatment surgery in two specialized surgical centers in Armenia during 2013-2014 years. Cases were patients with varicose veins and venous leg ulcers. Controls included patients with varicose veins but without venous leg ulcers. Data were collected using interviewer-administered telephone interviews and medical record abstraction. Multiple logistic regression analysis was used to identify the risk factors of venous ulceration. Results There were more females than males in both groups (72.5% of cases and 85.0 % of controls). Cases were on average older than controls (53.9 vs. 39.2 years old, p ≤ 0.001). After adjusting for potential confounders, the estimated odds of developing venous ulcer was higher in patients with history of post thrombotic syndrome (odds ratio = 14.90; 95% confidence interval: 3.95-56.19; p = 0.001), with higher average sitting time (odds ratio = 1.32 per hour of sitting time; 95% confidence interval: 1.08-1.61; p = 0.006), those with reflux in deep veins (odds ratio = 3.58; 95% confidence interval: 1.23-10.31; p = 0.019) and history of leg injury (odds ratio = 3.12; 95% confidence interval: 1.18-8.23; p = 0.022). Regular exercise in form of walking (≥5 days per week) was found to be a protective factor from venous ulceration (odds ratio = 0.26; 95% confidence interval: 0.08-0.90; p = 0.034). Conclusion We found that reflux in deep veins, history of leg injury, history of post thrombotic syndrome, and physical inactivity were significant risk factors for venous ulceration in patients with varicose veins, while
Oscillations in laser direct writing of W from WCl6 and H2: A theoretical analysis
Arnold, N.; Kargl, P. B.; Kullmer, R.; Bäuerle, D.
1995-10-01
The origin of oscillations observed in laser direct writing of W lines on quartz substrates is studied on the basis of a one-dimensional model. The dependence of oscillations on laser power, scanning velocity, etc., is discussed. The predictions are compared with experimental data. The present approach can be applied also to other systems, where such oscillations have a different origin.
Harsha, Asheesh K; Schmitt, J Eric; Stavropoulos, S William
2014-01-01
To analyze Internet search data to characterize the temporal and geographic interest of Internet users in the United States in varicose vein treatment. From January 1, 2004, to September 1, 2012, the Google Trends tool was used to analyze query data for "varicose vein treatment" to identify individuals seeking treatment information for varicose veins. The term "varicose vein treatment" returned a search volume index (SVI), representing the search frequency relative to the total search volume during a specific time interval and region. Linear regression analysis and Kruskal-Wallis one-way analysis of variance were employed to characterize search results. Search traffic for varicose vein treatment increased by 520% over the 104-month study period. There was an annual mean increase of 28% (range, -18%-100%; standard deviation [SD], 35%), with a statistically significant linear increase in average yearly SVI over time (R(2) = 0.94, P marketing dollars. © 2013 The Society of Interventional Radiology Published by SIR All rights reserved.
A memristor-based third-order oscillator: beyond oscillation
Talukdar, Abdul Hafiz Ibne
2012-10-06
This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.
A memristor-based third-order oscillator: beyond oscillation
Talukdar, A.; Radwan, A. G.; Salama, K. N.
2011-09-01
This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.
980-nm laser therapy versus varicose vein surgery in racially diverse Penang, Malaysia.
Lakhwani, Murli N; Dadlani, Navin I; Wong, Yong C
2009-05-01
Chronic venous disorders are conditions of increasing prevalence in the developing world, and venous ulceration is the terminal sequel. Currently there are only limited data on all aspects of this from Southeast Asia. The aim of the present study was to assess differences in the demography and outcome between varicose vein surgery (VVS) and the relatively new endovenous laser therapy (EVT) in patients from Penang, Malaysia. A retrospective study was performed. Patients who presented to the outpatient clinic of the surgical department with saphenofemoral junction and/or saphenopopliteal junction incompetence associated with reflux of the great saphenous vein or small saphenous vein, respectively, underwent either surgery (1999-2004) or laser therapy (2004-2006). A single surgeon at a single institution performed all procedures. A total of 350 limbs were treated from 292 patients. Demographics, symptoms, outcomes and complications that arose in both groups were compared. There were significant improvements in pains, swelling, cramps and heaviness postoperatively (P popular as an elective procedure with its minimally invasive nature, cosmesis, rapid recovery and other advantages. Surgery remains an important and very cost-effective procedure, especially in a developing society such as Penang.
Influence of Syringe Volume on Foam Stability in Sclerotherapy for Varicose Vein Treatment.
Bai, Taoping; Jiang, Wentao; Fan, Yubo
2017-11-14
Despite the popularity of sclerotherapy for treating varicose veins, it still exhibits various problems, such as pulmonary embolism, deep-vein thrombosis, phlebitis, and visual disorders. To investigate syringe volume influence on foam stability, obtain the foam decay rule, and provide a reference for clinics. Five types of syringes are used to prepare foam at room temperature with various liquid-gas ratios. Foam decay process experiments were performed 5 times and recorded by video. The stability indices used include drainage time, half-life, bubble diameter, bubble surface density, and drainage rate. The 30 and 2-mL syringes, respectively, recorded the highest and lowest drainage speeds. Foam drainage time and half-life, differences varied between 15 and 70 seconds, and 20 and 100 seconds, respectively. Foam bubble diameters were distributed over 0.1 to 2.0 mm with roughly 200 to 700 bubbles per square centimeter. Increased syringe volume causes the bubble diameter to increase. Thus, foam dispersion increases and foam half-life decreases; hence, foam becomes unstable. It is, thus, better to use a small syringe several times to prepare foam in clinics using segmented injections.
Varicose veins of the legs among nurses: Occupational and demographic characteristics.
Sharif Nia, Hamid; Chan, Yiong Huak; Haghdoost, Ali Akbar; Soleimani, Mohammad Ali; Beheshti, Zahra; Bahrami, Nasim
2015-06-01
This study aims to determine the relationship between occupational and demographic hazards that characterize varicose veins (VV) in the legs and their intensity among nurses.A cross-sectional study was carried out among 203 nurses from three general hospitals in Amol, Iran. The required subjects' information was collected through a self-filled questionnaire and the physical examination of the VV intensity was based on the Clinical finding using the Etiology, Anatomic finding, Pathophysiological standards. The prevalence of VV, with different degrees, was 72.4% (95% CI 65.7-78.4), with women having a higher prevalence compared with men (77.9% vs. 56.9%, P = 0.004). The other non-interventional risk variable was having longer years of service. Interventional variables were long-standing hours, overtime work and body mass index status. This study had determined the occupational risk variables on VV which could be interventional in improving the working nurses' environment and quality of life for their long-term career. © 2014 Wiley Publishing Asia Pty Ltd.
Jeong, Sangyun; Yang, Da-Som; Hong, Young Gi; Mitchell, Sarah P; Brown, Matthew P; Kolodkin, Alex L
2017-09-26
The transmembrane semaphorin Sema-1a acts as both a ligand and a receptor to regulate axon-axon repulsion during neural development. Pebble (Pbl), a Rho guanine nucleotide exchange factor, mediates Sema-1a reverse signaling through association with the N-terminal region of the Sema-1a intracellular domain (ICD), resulting in cytoskeletal reorganization. Here, we uncover two additional Sema-1a interacting proteins, varicose (Vari) and cheerio (Cher), each with neuronal functions required for motor axon pathfinding. Vari is a member of the membrane-associated guanylate kinase (MAGUK) family of proteins, members of which can serve as scaffolds to organize signaling complexes. Cher is related to actin filament cross-linking proteins that regulate actin cytoskeleton dynamics. The PDZ domain binding motif found in the most C-terminal region of the Sema-1a ICD is necessary for interaction with Vari, but not Cher, indicative of distinct binding modalities. Pbl/Sema-1a-mediated repulsive guidance is potentiated by both vari and cher Genetic analyses further suggest that scaffolding functions of Vari and Cher play an important role in Pbl-mediated Sema-1a reverse signaling. These results define intracellular components critical for signal transduction from the Sema-1a receptor to the cytoskeleton and provide insight into mechanisms underlying semaphorin-induced localized changes in cytoskeletal organization.
Karathanos, Christos; Exarchou, Maria; Tsezou, Aspasia; Kyriakou, Despina; Wittens, Cees; Giannoukas, Athanasios
2013-07-01
Superficial vein thrombosis (SVT) is a common and controversial clinical entity. Recent studies have demonstrated that SVT should be seen as a venous thromboembolism (VTE). The objective of this study was to investigate the prevalence of thrombophilia defects and to estimate the role of age, sex and body mass index (BMI) in patients with varicose veins (VVs) and SVT. A total of 230 patients with VVs, 128 with, and 102 without SVT underwent thrombophilia testing included factor V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase and plasminogen activator inhibitor- 1 mutations, protein C, protein S (PS), anti-thrombin III and plasminogen deficiencies and levels of A2 antiplasmin, activate protein C resistance and lupus anticoagulant. According to Clinical-Etiology-Anatomy-Pathophysiology (CEAP) classification patients were categorized in two subgroups: moderate disease (C2,3) and severe disease (C4,5,6). Age and body mass index were also assessed. The prevalence of thrombophilia defects was significantly higher in patients with moderate disease and SVT (p=0.002). In the C2,3 group, SVT was associated with PS deficiency (p=0.018), obesity (p<0.001), male gender (p=0.047) and age (p<0.001). There were no significant differences in patients with severe disease. Age, male sex, obesity and PS deficiency are factors associated with SVT development among patients with VVs having moderate disease (C2,3). Copyright © 2013 Elsevier Ltd. All rights reserved.
Kato, Shoji
2016-01-01
This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...
Jenkins, Alejandro
2013-04-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.
Small oscillations, Sturm sequences, and orthogonal polynomials
International Nuclear Information System (INIS)
Baake, M.
1986-07-01
The relation between small oscillations of one-dimensional mechanical systems and the theory of orthogonal polynomials is investigated. It is shown how the polynomials provide a natural tool to determine the eigenfrequencies and eigencoordinates completely, where the existence of a certain two-termed recurrence formula is essential. Physical and mathematical statements are formulated in terms of the recursion coefficients which can directly be obtained from the corresponding secular equation. Several known as well as new results on Sturm sequences and orthogonal polynomials are presented with respect to the treatment of small oscillations. (orig.)
Directory of Open Access Journals (Sweden)
P. A. Deymier
2016-12-01
Full Text Available We illustrate the concept of geometric phase in the case of two prototypical elastic systems, namely the one-dimensional harmonic oscillator and a one-dimensional binary superlattice. We demonstrate formally the relationship between the variation of the geometric phase in the spectral and wave number domains and the parallel transport of a vector field along paths on curved manifolds possessing helicoidal twists which exhibit non-conventional topology.
Integrable two dimensional supersystems
International Nuclear Information System (INIS)
Tripathy, K.C.; Tripathy, L.K.
1988-08-01
The integrability of two dimensional time-dependent classical systems is examined in N=2 superspace using Dirac's second class constraints. The invariants involving quadratic powers in velocities for super harmonic oscillator and super Kepler potentials have been derived. (author). 5 refs
Directory of Open Access Journals (Sweden)
Newton de Barros Junior
2010-06-01
Full Text Available Contexto: Durante e após a gestação, as varizes dos membros inferiores têm aspectos peculiares, tais como o seu aparecimento, a precocidade de seu desenvolvimento, a intensidade e, no puerpério, a rapidez com que regridem. Esses aspectos têm influenciado os estudos para a compreensão dessa patologia. Objetivo: Verificar a prevalência das varizes dos membros inferiores em gestantes e os fatores de risco mais relevantes envolvidos. A prevalência na gestação é alta, atingindo cerca de 70%, quando se consideram todos os tipos de varizes. Essa alta prevalência decorre principalmente do aumento nas taxas dos estrógenos e progestágenos que ocorre durante a gravidez. Material e método: Foram avaliadas 352 gestantes no período pré-natal, durante 14 meses, escolhidas ao acaso. A doença varicosa foi diagnosticada clinicamente e classificada segundo os critérios de Widmer em varizes tronculares, reticulares e telangiectasias e reclassificadas pela classificação CEAP, segundo o critério clínico. Os resultados de prevalência e fatores de risco foram submetidos às análises univariada e multivariada. Resultados: A prevalência da doença varicosa, quando considerados todos os tipos de varizes, foi de 72,7% (256 gestantes. As 96 gestantes (27,3% que não apresentaram doença varicosa foram consideradas, para análise estatística, como controle. Os fatores de risco de significância, após análise multivariada, foram: antecedente familiar positivo e idade. Conclusão: A prevalência da doença varicosa durante a gestação e os fatores de risco envolvidos indicam a necessidade de divulgação dessa patologia entre os profissionais envolvidos na prevenção e manutenção da saúde da mulher, especialmente aquelas em período fértil.Background: During and after pregnancy, lower limb varicose disease presents specific features that have influenced the conduction of studies designed to provide a better understanding of the condition
Indian Academy of Sciences (India)
straints [17], as a concrete example to study possible oscillating soliton structures in higher-dimensional physical models. The (2+1)-dimensional BK equations have been extensively studied in several papers [18–22]. Abundant solutions, such as soliton-like solutions, triangular-like solutions, single and combined ...
Quantization on the cone and cyon-oscillator duality
International Nuclear Information System (INIS)
Sisakyan, A.N.; Ter-Antonyan, V.M.
1996-01-01
It is shown that the three-dimensional isotropic oscillator with coordinates belonging to the two-dimensional half-up cone is dual to the cyon, i.e. the planar particle-vortex bound system provided by fractional statistics. 12 refs
Ismail, Lars; Normahani, Pasha; Standfield, Nigel J; Jaffer, Usman
2016-10-01
The association between pregnancy and the development of varicose veins is uncertain. We aimed to determine whether a history of pregnancy is associated with the development of varicose veins. We performed a systematic literature search using the databases of PubMed, Embase, Robert Koch-Institut, and Cochrane Central and the references of included papers. Eligible studies were all epidemiologic observational studies in which the outcome "varicose veins" and pregnancy history were assessed. The quality of each study was evaluated on the basis of the Dutch Cochrane review checklist and by the STROBE (Strengthening the Reporting of Observational Studies in Epidemiology) statement. For our meta-analysis, a random effects model was applied to pool odds ratios and 95% confidence intervals across studies. We found nine eligible studies enrolling 17,109 women. Pregnancy was associated with a significant risk increase in developing varicose veins. The results of our meta-analysis suggest that the odds for women with a history of pregnancy in developing varicose veins significantly increases by 82% (odds ratio, 1.82; 95% CI, 1.43-2.33) compared with women with no history of pregnancy. As expected for epidemiologic observational studies, the heterogeneity was considerably high (I(2) = 81%). Our meta-analysis strongly supports the hypothesis that there is a significant and strong association between a history of pregnancy and varicose veins. However, qualitative and quantitative differences among studies were evident and were also reflected in a considerably high heterogeneity. Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.
Svetukhin, A M; Askerov, N G; Batkaev, E A; Makhulaeva, A M; Malinina, V N
2008-01-01
During 2005-2007 128 patients at the age from 21 to 80 years with extensive trophic ulcers of legs were treated in the contaminated surgery department of A.V. Vishnevsky Surgery Institute and Korolenko Hospital. In 87 patients (69.9%) varicosity was the cause of venous insufficiency, in 41 patients--post-thrombotic disease. 23 patients (17.97%) had double-sided throphic ulcers. In 50 patients (39.1%) ulcer area exceeded 40 cm2. In microscopical analysis fungi were discovered in 87 patients (89.06%). In the remaining 15 patients diagnosis was verified culturally. System etiotropic antimycotic antibacterial treatment including hyposensitizative, anti-inflammatory, antihistamine drugs was carried out. 34 patients (26.57%) received broad spectrum antibiotic from terbinafine group (Terbizil) in dosage 250 mg once a day during 3 moths with concurrent use of topical antimycotics. 34 patients (26.56%) recieved pulse therapy with broad spectrum antibiotic Rumicoz 400 mg a day during 7 days in combination with topical antimycotics. Nizoral 400 mg a day during 30 days was prescribed to 26 patients (20.3%). 34 patients (26.56%) were treated only with topical antimycotics. After preoperative preparation and reduction of inflammatory process 64 patients had underwent excision of trophic ulcers whereupon the therapy was continued. In these patients regress of varicose eczema manifestation was achieved on the 10th day. In patients who hadn't received surgical cure regress of varicose eczema was signed on the 23-25th day after onset of treatment. Question of plastic closing of throphic ulcers and wounds after their excision was solved particularly. 14 patients needed recurring surgical management becose inflammatory process was continued. Comprehensive approach to therapy taking into account mycotic semination appears to be appropriate and effective. Proactive surgical tactics (excision of throphic ulcer) allows to quicken preoperative preparation for correction of venous blood
Sharrad, D F; Hibberd, T J; Kyloh, M A; Brookes, S J H; Spencer, N J
2015-07-10
In the gastrointestinal (GI) tract of mammals, endings of spinal afferent neurons with cell bodies in dorsal root ganglia (DRG) detect many stimuli, including those that give rise to pain. Many of these sensory neurons express calcitonin gene-related peptide (CGRP) and TRPV1 in their cell bodies and axons. Indeed, CGRP and TRPV1 have been widely used as immunohistochemical markers of nociceptive spinal afferent axons. Although CGRP and TRPV1 often coexist in the same axons in the GI tract, their degree of coexistence along its length has yet to be quantified. In this study, we used double-labeling immunohistochemistry to quantify the coexistence of CGRP and TRPV1 in varicose axons of the murine oesophagus, stomach and colorectum. The great majority of CGRP-immunoreactive (IR) varicosities in myenteric ganglia of the lower esophagus (97±1%) and stomach (95±1%) were also TRPV1-immunoreactive. Similarly, the majority of TRPV1-IR varicosities in myenteric ganglia of the lower esophagus (95±1%) and stomach (91±1%) were also CGRP-IR. In the colorectum similar observations were made for an intensely immunoreactive population of CGRP-IR axons, of which most (91±1%) were also TRPV1-IR. Of the TRPV1-IR axons in the colorectum, most (96±1%) contained intense CGRP-IR. Another population of axons in myenteric ganglia of the colorectum had low intensity CGRP immunoreactivity; these showed negligible co-existence with TRPV1. Our observations reveal that in the myenteric plexus of murine oesophagus, stomach and colorectum, CGRP and TRPV1 are largely expressed together. Copyright © 2015. Published by Elsevier Ireland Ltd.
Blood flow velocity in the Popliteal Vein using Transverse Oscillation Ultrasound
DEFF Research Database (Denmark)
Bechsgaard, Thor; Lindskov Hansen, Kristoffer; Brandt, Andreas Hjelm
2016-01-01
Chronic venous disease is a common condition leading to varicose veins, leg edema, post-thrombotic syndrome and venous ulcerations. Ultrasound (US) is the main modality for examination of venous disease. Color Doppler and occasionally spectral Doppler US (SDUS) are used for evaluation of the venous...... flow. Peak velocities measured by SDUS are rarely used in a clinical setting for evaluating chronic venous disease due to inadequate reproducibility mainly caused by the angle dependency of the estimate. However, estimations of blood velocities are of importance in characterizing venous disease....... Transverse Oscillation US (TOUS), a non-invasive angle independent method, has been implemented on a commercial scanner. TOUS’s advantage compared to SDUS is a more elaborate visualization of complex flow. The aim of this study was to evaluate, whether TOUS perform equal to SDUS for recording velocities...
Phenomenology of neutrino oscillations
Indian Academy of Sciences (India)
In this talk, I shall try to give a bird's eye view of the current status of neutrino oscillations. ..... the night effect. An asymmetry between the night and day rates would be an unambiguous signal for neutrino oscillations independent of the details of the solar ... It is particularly important to see the effect of the core of the earth [19].
Wessendorf, Kurt O.
2001-01-01
An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.
International Nuclear Information System (INIS)
Rodrigues, R. de Lima
2007-01-01
In the present work we obtain a new representation for the Dirac oscillator based on the Clifford algebra C 7. The symmetry breaking and the energy eigenvalues for our model of the Dirac oscillator are studied in the non-relativistic limit. (author)
Weger, J.G.; Water, van de W.; Molenaar, J.
2000-01-01
An impact oscillator is a periodically driven system that hits a wall when its amplitude exceeds a critical value. We study impact oscillations where collisions with the wall are with near-zero velocity (grazing impacts). A characteristic feature of grazing impact dynamics is a geometrically
Schubert, Tilman; Pansini, Michele; Bongartz, Georg; Niemann, Tilo
2011-01-01
Two patients, each with a history of multiple cancers, were referred to our institution for routine cancer staging. Contrast enhanced multislice-CT showed round and oval shaped inguinal and retroperitoneal masses in one patient and inguinal mass lesions in the other patient. The mass lesions were suspicious of lymphadenopathy related to cancer recurrence. Additional MR-Imaging, however, showed tortuous varicose veins as well as suspicious lymph nodes in one patient and solely venous convolutes in the other patient. Regarding the routine contrast enhanced CT-scan in the portovenous phase, varices showed no significant difference in radiodensity compared to enlarged lymph nodes. PMID:22470814
Energy Technology Data Exchange (ETDEWEB)
Hoseinzadeh, Samaneh; Shafiei, Babak; Salehian, Mohamadtaghi; Neshandar Asli, Isa; Ghodoosi, Iraj [Shaheed Beheshti Medical University, Tehran (Iran, Islamic Republic of)
2010-09-15
Ectopic varices (EcV) are enlarged portosystemic venous collaterals, which usually develop secondary to portal hypertension (PHT). Mesocaval collateral vessels are unusual pathways to decompress the portal system. Here we report the case of a huge varicose inferior mesenteric vein (IMV) that drained into peri rectal collateral veins, demonstrated by {sup 99m}Tc-labeled red blood cell (RBC) scintigraphy performed for lower gastrointestinal (GI) bleeding in a 14-year-old girl. This case illustrates the crucial role of {sup 99m}Tc-labeled RBC scintigraphy for the diagnosis of rare ectopic lower GI varices.
Higher prevalence of thrombophilia in patients with varicose veins and venous ulcers than controls.
Darvall, Katy A L; Sam, Rachel C; Adam, Donald J; Silverman, Stanley H; Fegan, Christopher D; Bradbury, Andrew W
2009-05-01
Uncontrolled studies suggest that patients with chronic venous ulceration (CVU) have an increased prevalence of thrombophilia, similar to that observed in patients with deep vein thrombosis. This study compared the nature and prevalence of thrombophilia in patients with varicose veins (VV, CEAP clinical [C] grade C(2) to C(3)) and patients with CVU (C(5) to C(6)) with an age- and sex-matched population without clinical or duplex ultrasound evidence of venous disease. Twenty-seven patients with VV, 27 patients with CVU, and 54 age- and sex-matched case controls with no clinical or duplex evidence of lower limb venous disease, underwent testing for factor V Leiden and prothrombin 20210A mutations, antithrombin deficiencies, and levels of antiphospholipid antibodies, homocysteine, protein C and S, and factor VIII, IX, and XI. The overall prevalences of single and multiple thrombophilias were significantly higher in cases than in controls. Specifically, in VV patients, the prevalences of no, single, and multiple thrombophilias were 33%, 52%, and 15%, respectively, compared with 63%, 26%, and 11% in VV controls. In CVU patients, the prevalences of no, single, and multiple thrombophilias was 26%, 30%, and 44%, respectively, compared with 66%, 22%, and 11% in CVU controls. Compared with controls, only factor XI levels were significantly higher in VV patients, and homocysteine and factor VIII, IX, and XI levels were all significantly higher in CVU patients. Patients with VV, and particularly CVU, have significantly higher prevalences of single and multiple thrombophilias than age- and sex-matched controls without clinical or duplex evidence of lower limb venous disease. These data support the hypothesis that thrombophilia predisposes to the development of superficial and deep lower limb venous reflux, and so VV and CVU, through the increased occurrence of clinical and subclinical thrombosis.
Optical-thermal mathematical model for endovenous laser ablation of varicose veins.
van Ruijven, Peter W M; Poluektova, Anna A; van Gemert, Martin J C; Neumann, H A Martino; Nijsten, Tamar; van der Geld, Cees W M
2014-03-01
Endovenous laser ablation (EVLA) is successfully used to treat varicose veins. However, the exact working mechanism is still not fully identified and the clinical procedure is not yet standardized. Mathematical modeling of EVLA could strongly improve our understanding of the influence of the various EVLA processes. The aim of this study is to combine Mordon's optical-thermal model with the presence of a strongly absorbing carbonized blood layer on the fiber tip. The model anatomy includes a cylindrically symmetric blood vessel surrounded by an infinite homogenous perivenous tissue. The optical fiber is located in the center of the vessel and is withdrawn with a pullback velocity. The fiber tip includes a small layer of strongly absorbing material, representing the layer of carbonized blood, which absorbs 45% of the emitted laser power. Heat transfer due to boiling bubbles is taken into account by increasing the heat conduction coefficient by a factor of 200 for temperatures above 95 °C. The temperature distribution in the blood, vessel wall, and surrounding medium is calculated from a numerical solution of the bioheat equation. The simulations were performed in MATLAB™ and validated with the aid of an analytical solution. The simulations showed, first, that laser wavelength did virtually not influence the simulated temperature profiles in blood and vessel wall, and, second, that temperatures of the carbonized blood layer varied slightly, from 952 to 1,104 °C. Our improved mathematical optical-thermal EVLA model confirmed previous predictions and experimental outcomes that laser wavelength is not an important EVLA parameter and that the fiber tip reaches exceedingly high temperatures.
The fractional oscillator process with two indices
International Nuclear Information System (INIS)
Lim, S C; Teo, L P
2009-01-01
We introduce a new fractional oscillator process which can be obtained as a solution of a stochastic differential equation with two fractional orders. Basic properties such as fractal dimension and short-range dependence of the process are studied by considering the asymptotic properties of its covariance function. By considering the fractional oscillator process as the velocity of a diffusion process, we derive the corresponding diffusion constant, fluctuation-dissipation relation and mean-square displacement. The fractional oscillator process can also be regarded as a one-dimensional fractional Euclidean Klein-Gordon field, which can be obtained by applying the Parisi-Wu stochastic quantization method to a nonlocal Euclidean action. The Casimir energy associated with the fractional field at positive temperature is calculated by using the zeta function regularization technique
Analysis of precision in chemical oscillators: implications for circadian clocks
International Nuclear Information System (INIS)
D'Eysmond, Thomas; De Simone, Alessandro; Naef, Felix
2013-01-01
Biochemical reaction networks often exhibit spontaneous self-sustained oscillations. An example is the circadian oscillator that lies at the heart of daily rhythms in behavior and physiology in most organisms including humans. While the period of these oscillators evolved so that it resonates with the 24 h daily environmental cycles, the precision of the oscillator (quantified via the Q factor) is another relevant property of these cell-autonomous oscillators. Since this quantity can be measured in individual cells, it is of interest to better understand how this property behaves across mathematical models of these oscillators. Current theoretical schemes for computing the Q factors show limitations for both high-dimensional models and in the vicinity of Hopf bifurcations. Here, we derive low-noise approximations that lead to numerically stable schemes also in high-dimensional models. In addition, we generalize normal form reductions that are appropriate near Hopf bifurcations. Applying our approximations to two models of circadian clocks, we show that while the low-noise regime is faithfully recapitulated, increasing the level of noise leads to species-dependent precision. We emphasize that subcomponents of the oscillator gradually decouple from the core oscillator as noise increases, which allows us to identify the subnetworks responsible for robust rhythms. (paper)
Harmonic oscillator Green's function
International Nuclear Information System (INIS)
Macek, J.H.; Ovchinnikov, S.Yu.; Khrebtukov, D.B.
2000-01-01
The Green's function for the harmonic oscillator in three dimensions plays an important role in the theory of atomic collisions. One representation of low-energy ion-atom collisions involves harmonic oscillator potentials. A closed-form expression for the harmonic oscillator Green's function, needed to exploit this representation, is derived. This expression is similar to the expression for the Coulomb Green's function obtained by Hostler and Pratt. Calculations of electron distributions for a model system of ion-atom collisions are reported to illustrate the theory.
Hauge, Jacob
2013-01-01
Unsteady foil theory is discussed and applied on several cases of an oscillating foil. The oscillating foil is meant as a propulsion system for a platform supply vessel.Four case studies of foil oscillation have been performed. A thrust coefficient of 0.1 was achieved at an efficiency of 0.75. A thrust coefficient of minimum 0.184 is necessary to overcome the calm water resistance of the foil.Issues connected to coupled vessel-foil models are discussed.
Kayser, Boris
2014-04-10
To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures.
International Nuclear Information System (INIS)
Agaisse, R.; Leguen, R.; Ombredane, D.
1960-01-01
The authors present a mechanical device and an electronic control circuit which have been designed to sinusoidally modulate the reactivity of the Proserpine atomic pile. The mechanical device comprises an oscillator and a mechanism assembly. The oscillator is made of cadmium blades which generate the reactivity oscillation. The mechanism assembly comprises a pulse generator for cycle splitting, a gearbox and an engine. The electronic device comprises or performs pulse detection, an on-off device, cycle pulse shaping, phase separation, a dephasing amplifier, electronic switches, counting scales, and control devices. All these elements are briefly presented
Frank, Michael; Says, Jerome; Denarié, Nicolas; Sapoval, Marc; Messas, Emmanuel
2016-04-01
We describe here the successful scheduled treatment of varicose veins by radiofrequency segmental thermal ablation in a 43-year-old patient with vascular Ehlers-Danlos syndrome. Her venous disease started at the age of 16 years, 1 year prior to her first major Ehlers-Danlos syndrome-related event which led to the diagnosis of her genetic condition. Surgical stripping was contra-indicated because of Ehlers-Danlos syndrome at the age of 18 years. More than 20 years later, her venous disease had become highly symptomatic despite daily compression and pain medication. Venous reassessment evidenced incompetent right and left great saphenous and left small saphenous veins, with increased diameters of both sapheno-femoral and sapheno-popliteal junctions. Radiofrequency endovenous ablation rather than surgery was considered because of its minimally invasive nature and because of standardized energy delivery.All intended-to-be-treated incompetent saphenous vein segments were occluded successfully, followed by an important improvement of clinical disease severity at day 30, persistent at 1 year post-treatment. Duplex ultrasound confirmed closure and fibrotic retraction of all treated venous segments at 1 year. This report shows that radiofrequency endovenous ablation may be a safe and effective therapy of varicose veins in patients with diagnosed vascular Ehlers-Danlos syndrome. © The Author(s) 2015.
2013-01-01
Objectives In contrast to other countries, surgery still represents the common invasive treatment for varicose veins in Germany. However, radiofrequency ablation, e.g. ClosureFast, becomes more and more popular in other countries due to potential better results and reduced side effects. This treatment option may cause less follow-up costs and is a more convenient procedure for patients, which could justify an introduction in the statutory benefits catalogue. Therefore, we aim at calculating the budget impact of a general reimbursement of ClosureFast in Germany. Methods To assess the budget impact of including ClosureFast in the German statutory benefits catalogue, we developed a multi-cohort Markov model and compared the costs of a “World with ClosureFast” with a “World without ClosureFast” over a time horizon of five years. To address the uncertainty of input parameters, we conducted three different types of sensitivity analysis (one-way, scenario, probabilistic). Results In the Base Case scenario, the introduction of the ClosureFast system for the treatment of varicose veins saves costs of about 19.1 Mio. € over a time horizon of five years in Germany. However, the results scatter in the sensitivity analyses due to limited evidence of some key input parameters. Conclusions Results of the budget impact analysis indicate that a general reimbursement of ClosureFast has the potential to be cost-saving in the German Statutory Health Insurance. PMID:23551943
Onk, Didem; Akarsu Ayazoğlu, Tülin; Kuyrukluyıldız, Ufuk; Aksüt, Mehmet; Bedir, Zehra; Küpeli, İlke; Onk, Oruç Alper; Alagöl, Ayşin
2016-02-12
BACKGROUND We sought to investigate the effect of morphine and fentanyl on shivering when used adjunctively with bupivacaine during spinal anesthesia in patients undergoing varicose vein surgery on an outpatient basis. MATERIAL AND METHODS The study included a total of 90 patients, aged 25-45 years, ASA I-II, scheduled to undergo endovenous laser ablation under spinal anesthesia for lower extremity venous insufficiency/varicose vein disease. Patients were randomly allocated into 3 groups: Group M (morphine group) received 5 mg 0.5% hyperbaric bupivacaine + 0.1 mg morphine, Group F (fentanyl group) received 5 mg 0.5% hyperbaric bupivacaine + 25 µg fentanyl, and Group C (control group) received 5 mg 0.5% hyperbaric bupivacaine + physiologic saline. The level of sensory blockade was assessed with pin-prick test and the level of motor blockade was assessed with Bromage scale at 5-min intervals. Shivering grade and time to first postoperative analgesic requirement was recorded. RESULTS Level and time of sensory block showed a slight but insignificant increase in the Morphine Group and Fentanyl Group. Time of postoperative analgesic requirement was significantly longer in patients who received morphine (pShivering was significantly less common in patients who received morphine and fentanyl than in patients who are in the Control Group (pshivering in patients undergoing venous surgery.
Viewing Majorana Bound States by Rabi Oscillations.
Wang, Zhi; Liang, Qi-Feng; Yao, Dao-Xin; Hu, Xiao
2015-07-08
We propose to use Rabi oscillation as a probe to view the fractional Josepshon relation (FJR) associated with Majorana bound states (MBSs) expected in one-dimensional topological superconductors. The system consists of a quantum dot (QD) and an rf-SQUID with MBSs at the Josephson junction. Rabi oscillations between energy levels formed by MBSs are induced by ac gate voltage controlling the coupling between QD and MBS when the photon energy proportional to the ac frequency matches gap between quantum levels formed by MBSs and QD. As a manifestation of the Rabi oscillation in the whole system involving MBSs, the electron occupation on QD oscillates with time, which can be measured by charge sensing techniques. With Floquet theorem and numerical analysis we reveal that from the resonant driving frequency for coherent Rabi oscillation one can directly map out the FJR cos(πΦ/Φ0) as a signature of MBSs, with Φ the magnetic flux through SQUID and Φ0 = hc/2e the flux quantum. The present scheme is expected to provide a clear evidence for MBSs under intensive searching.
Oscillating fluid power generator
Morris, David C
2014-02-25
A system and method for harvesting the kinetic energy of a fluid flow for power generation with a vertically oriented, aerodynamic wing structure comprising one or more airfoil elements pivotably attached to a mast. When activated by the moving fluid stream, the wing structure oscillates back and forth, generating lift first in one direction then in the opposite direction. This oscillating movement is converted to unidirectional rotational movement in order to provide motive power to an electricity generator. Unlike other oscillating devices, this device is designed to harvest the maximum aerodynamic lift forces available for a given oscillation cycle. Because the system is not subjected to the same intense forces and stresses as turbine systems, it can be constructed less expensively, reducing the cost of electricity generation. The system can be grouped in more compact clusters, be less evident in the landscape, and present reduced risk to avian species.
Fluctuations in LC Oscillators
Directory of Open Access Journals (Sweden)
O. Ondracek
1994-03-01
Full Text Available An analysis of the phase and amplitude fluctuations in oscillators with simple resonant circuit is presented. Negative feedback is used to minimize effect of the inherent noise produced by bipolar transistor on fluctuation characteristics.
High frequency nanotube oscillator
Peng, Haibing [Houston, TX; Zettl, Alexander K [Kensington, TX
2012-02-21
A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.
Again on neutrino oscillations
International Nuclear Information System (INIS)
Bilenky, S.M.; Pontecorvo, B.
1976-01-01
The general case is treated of a weak interaction theory in which a term violating lepton charges is present. In such a scheme the particles with definite masses are Majorana neutrinos (2N if in the weak interaction participate N four-component neutrinos). Neutrino oscillations are discussed and it is shown that the minimum average intensity at the earth of solar neutrinos is 1/2N of the intensity expected when oscillations are absent
Karathanos, Ch; Sfyroeras, G; Drakou, A; Roussas, N; Exarchou, M; Kyriakou, D; Giannoukas, A D
2012-03-01
To investigate the association of various risk factors including thrombophilia defects, in patients with varicose veins (VVs) and history of episodes of superficial vein thrombosis (SVT). Two hundred and thirty patients with primary VVs were included in this prospective study. A total of 128 (43 men, age 56 ± 13) had an acute episode or a previous history of SVT, while 102 patients (27 men, age 48 ± 12) did not. Coagulation profile investigation included serum levels of protein C (PC), protein S (PS), anti-thrombin III (AT III), plasminogen (Plg), A(2) antiplasmin (A(2)Apl) and activated protein C resistance (APCR). This was performed at least 3 months after the SVT episode to ensure that the results were not altered. Age and body mass index (BMI) were also assessed. PC deficiency was detected in 3/128 (2.3%), PS deficiency in 19/128 (14.8%), AT III deficiency in 29/128 (22.7%), Plg deficiency in 9/128 (7%), A(2)Apl excess in 3/128 (2.3%) and APCR in 9/128 (7%) patients with SVT and 0/102 (0%), 3/102 (2.9%), 15/102 (14.7%), 6/102 (5.8%), 0/102 (0%) and 1/102 (0.9%) in the control group, respectively. BMI greater than 30 kg m(-2) was associated with SVT. In logistic regression analysis SVT was associated with PS deficiency (odds ratio (OR) 6.7, p = 0.004, 95% confidence interval (CI) 1.83-24.53), obesity (OR 3.5, p = 0.003, 95% CI 1.53-8.05) and age (OR 1.038, p = 0.001, 95% CI 1.01-1.06). Obesity, age and PS deficiency were found as factors associated with SVT episodes in patients with VVs. Copyright © 2011 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
Solution of the anharmonic quartic potential oscillator problem
Sánchez, A. Martín; Bejarano, J. Díaz; Marzal, D. Caceres
1993-02-01
The problem of the one-dimensional generalized anharmonic quartic potential oscillator is studied in full. Solutions of the classical equations of motion for the different types of potential are given in terms of the Jacobi elliptic functions, in both classically allowed and forbidden regions of each potential for physically interesting initial conditions. The solutions and some of their properties are also given by means of bilinear transformations of the corresponding anharmonic symmetric oscillator solutions for similar regions or initial conditions.
Neutrino oscillations with LSND
International Nuclear Information System (INIS)
Stancu, Ion
2000-01-01
The Liquid Scintillator Neutrino Detector (LSND) at the Los Alamos Meson Physics Facility (LAMPF) has conducted searches for ν-bar μ → ν-bar e oscillations using ν-bar μ from μ + decay at rest (DAR) and for ν μ → ν e oscillations using ν μ from π + decay in flight (DIF). For the 1993-1995 data taking period, significant beam-excess events have been found in both oscillation channels. For the DAR search, a total excess of 51.8 +18.7 -16.9 ± 8.0 events from the ν-bar e p → e + n inverse β-decay reaction is observed, with e + energies between 20-60 MeV. For the DIF search, a total excess of 18.1 ± 6.6 ± 4.0 events from the ν e C → e - X inclusive reaction is observed, with e - energies between 60-200 MeV. If interpreted as neutrino oscillations, these excesses correspond to oscillation probabilities of (3.1±1.2±0.5) x 10 -3 and (2.6 ± 1.0 ± 0.5) x 10 -3 , respectively. Additional data collected during the 1996-1998 runs has been preliminarily analyzed for the DAR channel and yields very good agreement with the previously obtained results, for a combined oscillation probability of (3.3±0.9±0.5) x 10 -3
Neutrino oscillations in discrete-time quantum walk framework
Energy Technology Data Exchange (ETDEWEB)
Mallick, Arindam; Mandal, Sanjoy; Chandrashekar, C.M. [C. I. T. Campus, The Institute of Mathematical Sciences, Chennai (India); Homi Bhabha National Institute, Training School Complex, Mumbai (India)
2017-02-15
Here we present neutrino oscillation in the framework of quantum walks. Starting from a one spatial dimensional discrete-time quantum walk we present a scheme of evolutions that will simulate neutrino oscillation. The set of quantum walk parameters which is required to reproduce the oscillation probability profile obtained in both, long range and short range neutrino experiment is explicitly presented. Our scheme to simulate three-generation neutrino oscillation from quantum walk evolution operators can be physically realized in any low energy experimental set-up with access to control a single six-level system, a multiparticle three-qubit or a qubit-qutrit system. We also present the entanglement between spins and position space, during neutrino propagation that will quantify the wave function delocalization around instantaneous average position of the neutrino. This work will contribute towards understanding neutrino oscillation in the framework of the quantum information perspective. (orig.)
Directory of Open Access Journals (Sweden)
Sandeep G Jakhere
2011-01-01
Full Text Available A communicating vein between the left renal vein and the left ascending lumbar vein has only rarely been reported in the imaging literature. There are very few reports of varicosity of this communicating vein. Nonetheless, awareness about this communicating vein is of utmost importance for surgeons performing aortoiliac surgeries and nephrectomies as it may pose technical difficulties during surgery or cause life-threatening retroperitoneal hemorrhage. Varicosity of this venous channel may be mistaken for paraaortic lymphadenopathy, adrenal pseudo-mass, or renal artery aneurysm. We report a case of a patient with varicosity of this communicating vein, which mimicked a left renal artery aneurysm. A novel hypothesis is also proposed to explain the relationship with abdominal pain.
Photoinduced High-Frequency Charge Oscillations in Dimerized Systems
Yonemitsu, Kenji
2018-04-01
Photoinduced charge dynamics in dimerized systems is studied on the basis of the exact diagonalization method and the time-dependent Schrödinger equation for a one-dimensional spinless-fermion model at half filling and a two-dimensional model for κ-(bis[ethylenedithio]tetrathiafulvalene)2X [κ-(BEDT-TTF)2X] at three-quarter filling. After the application of a one-cycle pulse of a specifically polarized electric field, the charge densities at half of the sites of the system oscillate in the same phase and those at the other half oscillate in the opposite phase. For weak fields, the Fourier transform of the time profile of the charge density at any site after photoexcitation has peaks for finite-sized systems that correspond to those of the steady-state optical conductivity spectrum. For strong fields, these peaks are suppressed and a new peak appears on the high-energy side, that is, the charge densities mainly oscillate with a single frequency, although the oscillation is eventually damped. In the two-dimensional case without intersite repulsion and in the one-dimensional case, this frequency corresponds to charge-transfer processes by which all the bonds connecting the two classes of sites are exploited. Thus, this oscillation behaves as an electronic breathing mode. The relevance of the new peak to a recently found reflectivity peak in κ-(BEDT-TTF)2X after photoexcitation is discussed.
The SUSY oscillator from local geometry: Dynamics and coherent states
International Nuclear Information System (INIS)
Thienel, H.P.
1994-01-01
The choice of a coordinate chart on an analytical R n (R a n ) provides a representation of the n-dimensional SUSY oscillator. The corresponding Hilbert space is Cartan's exterior algebra endowed with a suitable scalar product. The exterior derivative gives rise to the algebra of the n-dimensional SUSY oscillator. Its euclidean dynamics is an inherent consequence of the geometry imposed by the Lie derivative generating the dilations, i.e. evolution of the quantum system corresponds to parametrization of a sequence of charts by euclidean time. Coherent states emerge as a natural structure related to the Lie derivative generating the translations. (orig.)
Endovascular laser therapy for varicose veins: an evidence-based analysis.
2010-01-01
The objective of the MAS evidence review was to conduct a systematic review of the available evidence on the safety, effectiveness, durability and cost-effectiveness of endovascular laser therapy (ELT) for the treatment of primary symptomatic varicose veins (VV). The Ontario Health Technology Advisory Committee (OHTAC) met on November 27, 2009 to review the safety, effectiveness, durability and cost-effectiveness of ELT for the treatment of primary VV based on an evidence-based review by the Medical Advisory Secretariat (MAS). CLINICAL CONDITION: VV are tortuous, twisted, or elongated veins. This can be due to existing (inherited) valve dysfunction or decreased vein elasticity (primary venous reflux) or valve damage from prior thrombotic events (secondary venous reflux). The end result is pooling of blood in the veins, increased venous pressure and subsequent vein enlargement. As a result of high venous pressure, branch vessels balloon out leading to varicosities (varicose veins). SYMPTOMS TYPICALLY AFFECT THE LOWER EXTREMITIES AND INCLUDE (BUT ARE NOT LIMITED TO): aching, swelling, throbbing, night cramps, restless legs, leg fatigue, itching and burning. Left untreated, venous reflux tends to be progressive, often leading to chronic venous insufficiency (CVI). A NUMBER OF COMPLICATIONS ARE ASSOCIATED WITH UNTREATED VENOUS REFLUX: including superficial thrombophlebitis as well as variceal rupture and haemorrhage. CVI often results in chronic skin changes referred to as stasis dermatitis. Stasis dermatitis is comprised of a spectrum of cutaneous abnormalities including edema, hyperpigmentation, eczema, lipodermatosclerosis and stasis ulceration. Ulceration represents the disease end point for severe CVI. CVI is associated with a reduced quality of life particularly in relation to pain, physical function and mobility. In severe cases, VV with ulcers, QOL has been rated to be as bad or worse as other chronic diseases such as back pain and arthritis. Lower limb VV is a
Energy Technology Data Exchange (ETDEWEB)
Hoeye, Gudrun Kristine
1999-07-01
We have studied radial and nonradial oscillations in neutron stars, both in a general relativistic and non-relativistic frame, for several different equilibrium models. Different equations of state were combined, and our results show that it is possible to distinguish between the models based on their oscillation periods. We have particularly focused on the p-, f-, and g-modes. We find oscillation periods of II approx. 0.1 ms for the p-modes, II approx. 0.1 - 0.8 ms for the f-modes and II approx. 10 - 400 ms for the g-modes. For high-order (l (>{sub )} 4) f-modes we were also able to derive a formula that determines II{sub l+1} from II{sub l} and II{sub l-1} to an accuracy of 0.1%. Further, for the radial f-mode we find that the oscillation period goes to infinity as the maximum mass of the star is approached. Both p-, f-, and g-modes are sensitive to changes in the central baryon number density n{sub c}, while the g-modes are also sensitive to variations in the surface temperature. The g-modes are concentrated in the surface layer, while p- and f-modes can be found in all parts of the star. The effects of general relativity were studied, and we find that these are important at high central baryon number densities, especially for the p- and f-modes. General relativistic effects can therefore not be neglected when studying oscillations in neutron stars. We have further developed an improved Cowling approximation in the non-relativistic frame, which eliminates about half of the gap in the oscillation periods that results from use of the ordinary Cowling approximation. We suggest to develop an improved Cowling approximation also in the general relativistic frame. (Author)
Poluektova, Anna A; Malskat, Wendy S J; van Gemert, Martin J C; Vuylsteke, Marc E; Bruijninckx, Cornelis M A; Neumann, H A Martino; van der Geld, Cees W M
2014-03-01
Minimally invasive treatment of varicose veins by endovenous laser ablation (EVLA) becomes more and more popular. However, despite significant research efforts performed during the last years, there is still a lack of agreement regarding EVLA mechanisms and therapeutic strategies. The aim of this article is to address some of these controversies by utilizing optical-thermal mathematical modeling. Our model combines Mordon's light absorption-based optical-thermal model with the thermal consequences of the thin carbonized blood layer on the laser fiber tip that is heated up to temperatures of around 1,000 °C due to the absorption of about 45% of the laser light. Computations were made in MATLAB. Laser wavelengths included were 810, 840, 940, 980, 1,064, 1,320, 1,470, and 1,950 nm. We addressed (a) the effect of direct light absorption by the vein wall on temperature behavior, comparing computations by using normal and zero wall absorption; (b) the prediction of the influence of wavelength on the temperature behavior; (c) the effect of the hot carbonized blood layer surrounding the fiber tip on temperature behavior, comparing wall temperatures from using a hot fiber tip and one kept at room temperature; (d) the effect of blood emptying the vein, simulated by reducing the inside vein diameter from 3 down to 0.8 mm; (e) the contribution of absorbed light energy to the increase in total energy at the inner vein wall in the time period where the highest inner wall temperature was reached; (f) the effect of laser power and pullback velocity on wall temperature of a 2-mm inner diameter vein, at a power/velocity ratio of 30 J/cm at 1,470 nm; (g) a comparison of model outcomes and clinical findings of EVLA procedures at 810 nm, 11 W, and 1.25 mm/s, and 1,470 nm, 6 W, and 1 mm/s, respectively. Interestingly, our model predicts that the dominating mechanism for heating up the vein wall is not direct absorption of the laser light by the vein wall but, rather, heat flow to the
Alabdulmohsin, Ibrahim M.
2018-03-07
In this chapter, we use the theory of summability of divergent series, presented earlier in Chap. 4, to derive the analogs of the Euler-Maclaurin summation formula for oscillating sums. These formulas will, in turn, be used to perform many remarkable deeds with ease. For instance, they can be used to derive analytic expressions for summable divergent series, obtain asymptotic expressions of oscillating series, and even accelerate the convergence of series by several orders of magnitude. Moreover, we will prove the notable fact that, as far as the foundational rules of summability calculus are concerned, summable divergent series behave exactly as if they were convergent.
Hagedorn, Peter
1982-01-01
Thoroughly revised and updated, the second edition of this concise text provides an engineer's view of non-linear oscillations, explaining the most important phenomena and solution methods. Non-linear descriptions are important because under certain conditions there occur large deviations from the behaviors predicted by linear differential equations. In some cases, completely new phenomena arise that are not possible in purely linear systems. The theory of non-linear oscillations thus has important applications in classical mechanics, electronics, communications, biology, and many other branches of science. In addition to many other changes, this edition has a new section on bifurcation theory, including Hopf's theorem.
Friedel oscillations in graphene
DEFF Research Database (Denmark)
Lawlor, J. A.; Power, S. R.; Ferreira, M.S.
2013-01-01
Symmetry breaking perturbations in an electronically conducting medium are known to produce Friedel oscillations in various physical quantities of an otherwise pristine material. Here we show in a mathematically transparent fashion that Friedel oscillations in graphene have a strong sublattice...... asymmetry. As a result, the presence of impurities and/or defects may impact the distinct graphene sublattices very differently. Furthermore, such an asymmetry can be used to explain the recent observations that nitrogen atoms and dimers are not randomly distributed in graphene but prefer to occupy one...
Oscillators from nonlinear realizations
Kozyrev, N.; Krivonos, S.
2018-02-01
We construct the systems of the harmonic and Pais-Uhlenbeck oscillators, which are invariant with respect to arbitrary noncompact Lie algebras. The equations of motion of these systems can be obtained with the help of the formalism of nonlinear realizations. We prove that it is always possible to choose time and the fields within this formalism in such a way that the equations of motion become linear and, therefore, reduce to ones of ordinary harmonic and Pais-Uhlenbeck oscillators. The first-order actions, that produce these equations, can also be provided. As particular examples of this construction, we discuss the so(2, 3) and G 2(2) algebras.
Seasonality and mechanisms of tropical intraseasonal oscillations
Hazra, Abheera; Krishnamurthy, V.
2018-01-01
This study has compared the monsoon intraseasonal oscillation (MISO) during the boreal summer and Madden Julian Oscillation (MJO) during the boreal winter. Based on MISO and MJO in high-resolution three-dimensional diabatic heating, the possible mechanisms are discussed through observational analyses of dynamical and thermodynamical variables. The MISO and MJO are extracted as nonlinear oscillations during boreal summer and winter, respectively, by applying multi-channel singular spectrum analysis on daily anomalies of diabatic heating over the Indo-Pacific region. Lead and lag relations among moisture, temperature and surface fields relative to diabatic heating are analyzed to compare the mechanisms of MISO and MJO. While both the oscillations show eastward propagation, MISO has a strong northward propagation and MJO has a weak southward propagation as well. The analysis shows that MJO and MISO are essentially driven by the same mechanisms but with some difference in the meridional propagation. The westerly shear leads the diabatic heating, while the vorticity has weak correlation. Large-scale circulation creates positive moisture preconditioning before convection and negative moisture preconditioning before suppressed conditions. A positive lower level horizontal advection of temperature and upper level temperature tendencies lead the convective state while a negative lower level horizontal advection of temperature and upper level temperature tendencies lead the suppressed state. There is positive feedback from the SST to atmosphere. The difference in the meridional propagation of MISO and MJO is hypothesized to be because of the different differential heating meridionally during the two seasons.
Modeling microtubule oscillations
DEFF Research Database (Denmark)
Jobs, E.; Wolf, D.E.; Flyvbjerg, H.
1997-01-01
Synchronization of molecular reactions in a macroscopic volume may cause the volume's physical properties to change dynamically and thus reveal much about the reactions. As an example, experimental time series for so-called microtubule oscillations are analyzed in terms of a minimal model for thi...
Neutrino oscillation experiments
International Nuclear Information System (INIS)
Camilleri, L.
1996-01-01
Neutrino oscillation experiments (ν μ →ν e and ν μ →ν τ ) currently being performed at accelerators are reviewed. Future plans for short and long base-line experiments are summarized. (author) 10 figs., 2 tabs., 29 refs
Jones, R. T.
1976-01-01
For acoustic tests the violin is driven laterally at the bridge by a small speaker of the type commonly found in pocket transistor radios. An audio oscillator excites the tone which is picked up by a sound level meter. Gross patterns of vibration modes are obtained by the Chladni method.
The variational spiked oscillator
International Nuclear Information System (INIS)
Aguilera-Navarro, V.C.; Ullah, N.
1992-08-01
A variational analysis of the spiked harmonic oscillator Hamiltonian -d 2 / d x 2 + x 2 + δ/ x 5/2 , δ > 0, is reported in this work. A trial function satisfying Dirichlet boundary conditions is suggested. The results are excellent for a large range of values of the coupling parameter. (author)
From excitability to oscillations
DEFF Research Database (Denmark)
Postnov, D. E.; Neganova, A. Y.; Jacobsen, J. C. B.
2013-01-01
One consequence of cell-to-cell communication is the appearance of synchronized behavior, where many cells cooperate to generate new dynamical patterns. We present a simple functional model of vasomotion based on the concept of a two-mode oscillator with dual interactions: via relatively slow...
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef
2007-01-01
A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...
Neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Camilleri, L. [European Organization for Nuclear Research, Geneva (Switzerland)
1996-11-01
Neutrino oscillation experiments ({nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub {tau}}) currently being performed at accelerators are reviewed. Future plans for short and long base-line experiments are summarized. (author) 10 figs., 2 tabs., 29 refs.
Nonlinearity in oscillating bridges
Directory of Open Access Journals (Sweden)
Filippo Gazzola
2013-09-01
Full Text Available We first recall several historical oscillating bridges that, in some cases, led to collapses. Some of them are quite recent and show that, nowadays, oscillations in suspension bridges are not yet well understood. Next, we survey some attempts to model bridges with differential equations. Although these equations arise from quite different scientific communities, they display some common features. One of them, which we believe to be incorrect, is the acceptance of the linear Hooke law in elasticity. This law should be used only in presence of small deviations from equilibrium, a situation which does not occur in widely oscillating bridges. Then we discuss a couple of recent models whose solutions exhibit self-excited oscillations, the phenomenon visible in real bridges. This suggests a different point of view in modeling equations and gives a strong hint how to modify the existing models in order to obtain a reliable theory. The purpose of this paper is precisely to highlight the necessity of revisiting the classical models, to introduce reliable models, and to indicate the steps we believe necessary to reach this target.
International Nuclear Information System (INIS)
Haxton, W.C.
1993-01-01
The special properties of solar neutrinos that render this flux so uniquely important in searches for neutrino masses and flavor mixing are reviewed. The effects of matter, including density fluctuations and turbulence, on solar neutrino oscillations are explained through analogies with more familiar atomic physics phenomena
Charge oscillations in orbitrons
International Nuclear Information System (INIS)
Porto, M.; Gomes, L.C.
1981-01-01
A statistical model for the electron distribution in orbitrons is constructed where the effect of the end plates is considered. A comparison is made with the measured density of charge. The electromagnetic oscillations generated by orbitrons are calculated as pressure waves and the results obtained are compared with the data. (Author) [pt
solar neutrino oscillation phenomenology
Indian Academy of Sciences (India)
sRUBABATI GOsWAMI. Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211 019, India. Email: sruba@mri.ernet.in. Abstract. This article summarises the status of the solar neutrino oscillation phe- nomenology at the end of 2002 in the light of the SNO and KamLAND results. We first present the allowed ...
8D oscillator as a hidden SU(2)-monopole
International Nuclear Information System (INIS)
Mardoyan, L.G.; Sisakyan, A.N.; Ter-Antonyan, V.M.
1998-01-01
In the framework of an analytical approach and with the help of the generalized version of the Hurwitz transformation the five-dimensional SU(2)-monopole model is constructed from the eight-dimensional quantum oscillator. The Clebsch-Gordan expansion stimulated by the space-gauge coupling, the hyperangle and the radial parts of the total wave function, the energy spectrum of the charge-monopole bound system and the corresponding degeneracy are calculated
Low-frequency oscillations in narrow vibrated granular systems
Rivas, Nicolas; Luding, Stefan; Thornton, Anthony R
2013-01-01
We present simulations and a theoretical treatment of vertically vibrated granular media. The systems considered are confined in narrow quasi-two-dimensional and quasi-one-dimensional (column) geometries, where the vertical extension of the container is much larger than both horizontal lengths. The additional geometric constraint present in the column setup frustrates the convection state that is normally observed in wider geometries. This makes it possible to study collective oscillations of...
The Lorentzian oscillator group as a geodesic orbit space
Energy Technology Data Exchange (ETDEWEB)
Batat, W. [Ecole Normale Superieure d' Enseignement Technologique d' Oran, Departement de Mathematiques et Informatique, B.P. 1523, El M' Naouar, Oran (Algeria); Gadea, P. M. [Instituto de Fisica Fundamental, CSIC, Serrano 113-bis, 28006 Madrid (Spain); Oubina, J. A. [Departamento de Xeometria e Topoloxia, Facultade de Matematicas, Universidade de Santiago de Compostela, 15782 Santiago de Compostela (Spain)
2012-10-15
We prove that the four-dimensional oscillator group Os, endowed with any of its usual left-invariant Lorentzian metrics, is a Lorentzian geodesic (so, in particular, null-geodesic) orbit space with some of its homogeneous descriptions corresponding to certain homogeneous Lorentzian structures. Each time that Os is endowed with a suitable metric and an appropriate homogeneous Lorentzian structure, it is a candidate for constructing solutions in d-dimensional supergravity with at least 24 of the 32 possible supersymmetries.
Adiabatic and non-adiabatic electron oscillations in a static electric field
International Nuclear Information System (INIS)
Wahlberg, C.
1977-03-01
The influence of a static electric field on the oscillations of a one-dimensional stream of electrons is investigated. In the weak field limit the oscillations are adiabatic and mode coupling negligible, but becomes significant if the field is tronger. The latter effect is believed to be of importance for the stability of e.g. potential double layers
Bimodal oscillations in nephron autoregulation
DEFF Research Database (Denmark)
Sosnovtseva, Olga; Pavlov, A N; Mosekilde, E
2002-01-01
The individual functional unit of the kidney (the nephron) displays oscillations in its pressure and flow regulation at two different time scales: fast oscillations associated with a myogenic dynamics of the afferent arteriole, and slower oscillations arising from a delay in the tubuloglomerular ...
Energy Technology Data Exchange (ETDEWEB)
Ko, Myong Kwan; Lee, Hee; Kang, Sung Gwon; Choi, Jeong Yeol; Byun, Ju Nam; Jang, Jeong Hwan; Lim, Chae Ha [Chosun Univ. College of Medicine, Kwangju (Korea, Republic of); Kim, Young Cheol [Yeong Gwang Christian Hospital, Yeong Gwang (Korea, Republic of)
2001-11-01
To assess the performance of contrast-enhanced three-dimensional(3-D) magnetic resonance venography (MRV) of the pelvis and lower extremities in patients with varicose veins. Ascending and MR venography were performed in seven legs of seven patients, and duplex Doppler sonography and MR venography in 15 legs of 12 patients, all referred for evaluation of varicose veins. For analysis, the venous system as revealed by ascending and MR venographic images was divided into 13 segments. For detection of reflux to the great saphenous vein, duplex Doppler sonography and MRV were performed. In ascending venography and MRV, 91 venous segments were potentially visible; both modalities depicted 78 of these, but failed to detect four. Ascending venography and MRV detected 17 and 19 varices, respectively. When two tourniquets were placed around the ankle and knee using the Valsalva maneuver, MRV and duplex Doppler sonography detected reflux in 8 or 11 and 13 or 15 legs, respectively. Contrast-enhanced 3-D MRV comprehensively displays the venous system of the lower extremities and permits assessment of varicose veins. MRV using the Valsalva maneuver allows assessment of reflux to the great saphenous vein.
Hall, Helen; Lauche, Romy; Adams, Jon; Steel, Amie; Broom, Alex; Sibbritt, David
2016-02-01
Common discomforts of pregnancy experienced in the lower extremity include sciatica, leg cramps and varicose veins. Whilst research attention has focused on aetiology and outcomes, the health service utilisation of pregnant women suffering from these complaints has been largely overlooked. To examine the health status and health service utilisation profile of pregnant women experiencing sciatica, leg cramps or varicose veins. Linear and logistic regression was applied to a cross-sectional survey of a pregnant women drawn from the 1973 to 1978 cohort (aged 31-36 years in 2009), of the Australian Longitudinal Study on Women's Health (n=1835). Participant's demographics, health status and health service utilisation were compared for all three complaints based upon three subgroups (yes, sought help; yes, did not seek help; no). A number of women experienced sciatica (22.1%), leg cramps (18.2%) or varicose veins (9.4%). Of these, a greater proportion of women with sciatica (79.3%) or varicose veins (71.5%) sought help for their condition compared with women with leg cramps (46.7%). Comparisons between women with the conditions of interest who did seek help and those who did not only found that women with a university degree were 0.29 (95% CI: 0.10, 0.85) times less likely to seek help for their condition compared to women with a school only education. Further research examining all health seeking behaviour and treatment use of pregnant women who experience lower extremity problems is required in order to facilitate safe, effective and coordinated maternity care to further support these women during pregnancy. Copyright © 2015 Australian College of Midwives. Published by Elsevier Ltd. All rights reserved.
Atasoy, M M
2015-01-01
To define and assess the short-term clinical feasibility of fill and aspirate foam sclerotherapy (FAFS) for treating large superficial varicose veins concomitant to endovenous laser ablation (EVLA). Twenty-seven patients who refused to have phlebectomies with great saphenous vein reflux and large superficial varicosities were included in the study. Both EVLA and FAFS were performed concomitantly. FAFS is a technique in which all or most of the bubbles and blood-foam mixture are removed from the targeted large varicose veins immediately after the foam has caused sufficient damage to the endothelial cells. Patients were reviewed 1 month and 6 months after the treatment. Improvement in the clinical, aetiological, anatomical, and pathological classification (CEAP), and clinical severity was graded using the revised venous clinical severity score (rVCSS) and cosmetic results were investigated at the 6 month visit. Ablation of GSV was performed in 27 limbs in 27 patients (19 males, 70.3%; mean age 44 years; range 21-69 years). All patients had a technically successful FAFS treatment. The CEAP classification score, the rVCSS values, and the cosmetic results showed prominent improvement 6 months after the treatment. There were no significant complications, such as stroke, skin burns, necrosis, paresthesia, deep-vein thrombosis, or allergic reaction. None of the patients experienced neurological events. FAFS is a promising safe and effective technique for treating large superficial varicosities concomitant to EVLA of the truncal veins with excellent clinical results. Randomized prospective studies with larger series are required to compare the FAFS with ambulatory phlebectomy and standard foam sclerotherapy. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.
Parametric Resonance in a Time-Dependent Harmonic Oscillator
Directory of Open Access Journals (Sweden)
P. N. Nesterov
2013-01-01
Full Text Available In this paper, we study the phenomenon of appearance of new resonances in a timedependent harmonic oscillator under an oscillatory decreasing force. The studied equation belongs to the class of adiabatic oscillators and arises in connection with the spectral problem for the one-dimensional Schr¨odinger equation with Wigner–von Neumann type potential. We use a specially developed method for asymptotic integration of linear systems of differential equations with oscillatory decreasing coefficients. This method uses the ideas of the averaging method to simplify the initial system. Then we apply Levinson’s fundamental theorem to get the asymptotics for its solutions. Finally, we analyze the features of a parametric resonance phenomenon. The resonant frequencies of perturbation are found and the pointwise type of the parametric resonance phenomenon is established. In conclusion, we construct an example of a time-dependent harmonic oscillator (adiabatic oscillator in which the parametric resonances, mentioned in the paper, may occur.
Relaxation oscillations and transport barrier dynamics in tokamak edge plasmas
International Nuclear Information System (INIS)
Benkadda, Sadruddin; Beyer, Peter; Fuhr-Chaudier, Guillaume; Garbet, Xavier; Ghendrih, Philippe; Sarazin, Yanick
2004-01-01
Oscillations of turbulent transport of particles and energy in magnetically confined plasmas can be easily observed in simulations of a variety of turbulence models. These oscillations typically involve a mechanism of energy exchange between fluctuations and a poloidal shear flow. This kind of ''predator-prey'' mechanism is found to be not relevant for transport barrier relaxations. In RBM simulations of resistive ballooning turbulence with transport barrier, relaxation oscillations of the latter are observed even in the case of frozen poloidal shear flow. These relaxations are due to a transitory growth of a mode localized at the barrier center. A one-dimensional model for the evolution of such a mode in the presence of a shear flow describes a transitory growth of an initial perturbation. Oscillations in the case of a finite steady-state shear flow are possible due to the coupling of the mode to the dynamics of the pressure profile. (author)
Observation and analysis of oscillations in linear accelerators
International Nuclear Information System (INIS)
Seeman, J.T.
1991-11-01
This report discusses the following on oscillation in linear accelerators: Betatron Oscillations; Betatron Oscillations at High Currents; Transverse Profile Oscillations; Transverse Profile Oscillations at High Currents.; Oscillation and Profile Transient Jitter; and Feedback on Transverse Oscillations
Comparison of alternative improved perturbative methods for nonlinear oscillations
International Nuclear Information System (INIS)
Amore, Paolo; Raya, Alfredo; Fernandez, Francisco M.
2005-01-01
We discuss and compare two alternative perturbation approaches for the calculation of the period of nonlinear systems based on the Lindstedt-Poincare technique. As illustrative examples we choose one-dimensional anharmonic oscillators and the Van der Pol equation. Our results show that each approach is better for just one type of model considered here
Approximate solutions of the Wei Hua oscillator using the Pekeris ...
Indian Academy of Sciences (India)
The approximate analytical bound-state solutions of the Schrödinger equation for the. Wei Hua oscillator are carried out in N-dimensional space by taking Pekeris approximation scheme to the orbital centrifugal term. Solutions of the corresponding hyper-radial equation are obtained using the conventional Nikiforov–Uvarov ...
Phase-space treatment of the driven quantum harmonic oscillator
Indian Academy of Sciences (India)
A recent phase-space formulation of quantum mechanics in terms of the Glauber coherent states is applied to study the interaction of a one-dimensional harmonic oscillator with an arbitrary time-dependent force. Wave functions of the simultaneous values of position q and momentum p are deduced, which in turn give the ...
Canard Phenomena in Oscillations of a Surface Oxidation Reaction
Xie, Feng; Han, Maoan; Zhang, Weijiang
2005-12-01
In this paper we investigate canard phenomena occurring in oscillations of a surface oxidation reaction which can be modeled by a three-dimensional singularly perturbed system of ordinary differential equations with two fast variables. By using asymptotic methods, we prove the existence of the maximal canard of the mentioned model, and provide sufficient conditions for the existence of stable canard cycles.
Time dependent analysis of Xenon spatial oscillations in small power reactors
International Nuclear Information System (INIS)
Decco, Claudia Cristina Ghirardello
1997-01-01
This work presents time dependent analysis of xenon spatial oscillations studying the influence of the power density distribution, type of reactivity perturbation, power level and core size, using the one-dimensional and three-dimensional analysis with the MID2 and citation codes, respectively. It is concluded that small pressurized water reactors with height smaller than 1.5 m are stable and do not have xenon spatial oscillations. (author)
Seismic metamaterials based on isochronous mechanical oscillators
Energy Technology Data Exchange (ETDEWEB)
Finocchio, G., E-mail: gfinocchio@unime.it; Garescì, F.; Azzerboni, B. [Department of Electronic Engineering, Industrial Chemistry and Engineering, University of Messina, C.da di Dio, I-98166 Messina (Italy); Casablanca, O.; Chiappini, M. [Istituto Nazionale di Geofisica e Vulcanologia (INGV), Via Vigna Murata 605, 00143 Roma (Italy); Ricciardi, G. [Department of Civil, Informatic, Architectural, and Environmental Engineering and Applied Mathematics, C.da di Dio, I-98166 Messina (Italy); Alibrandi, U. [Department of Civil and Environmental Engineering, National University of Singapore, 1 Engineering Drive 2, Singapore 117576 (Singapore)
2014-05-12
This Letter introduces a seismic metamaterial (SM) composed by a chain of mass-in-mass system able to filter the S-waves of an earthquake. We included the effect of the SM into the mono dimensional model for the soil response analysis. The SM modifies the soil behavior and in presence of an internal damping the amplitude of the soil amplification function is reduced also in a region near the resonance frequency. This SM can be realized by a continuous structure with inside a 3d-matrix of isochronous oscillators based on a sphere rolling over a cycloidal trajectory.
Acoustics waves and oscillations
Sen, S.N.
2013-01-01
Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...
Nonlinear (Anharmonic Casimir Oscillator
Directory of Open Access Journals (Sweden)
Habibollah Razmi
2011-01-01
Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.
Plasma oscillations in porous samples
Directory of Open Access Journals (Sweden)
Kornyushin Y.
2004-01-01
Full Text Available The influence of the shape of a sample on the type of uniform dipole collective electrons oscillations is discussed. In samples of a bulk shape uniform bulk dipole oscillations cannot exist. They exist in samples of a thin slab shape only. However in essentially porous materials the electrostatic energy of the oscillation in a sample is considerably larger thus leading to stronger restoring force and higher frequency of the oscillation. When this frequency exceeds the Langmuir frequency, the oscillation becomes of a bulk type. .
Neutrino Masses and Oscillations
CERN. Geneva. Audiovisual Unit; Treille, Daniel
2002-01-01
This course will not cover its subject in the customary way. The emphasis will be on the simple theoretical concepts (helicity, handedness, chirality, Majorana masses) which are obscure in most of the literature, and on the quantum mechanics of oscillations, that ALL books get wrong. Which, hopefully, will not deter me from discussing some of the most interesting results from the labs and from the cosmos.
Oscillations in quasineutral plasmas
International Nuclear Information System (INIS)
Grenier, E.
1996-01-01
The purpose of this article is to describe the limit, as the vacuum electric permittivity goes to zero, of a plasma physics system, deduced from the Vlasov-Poisson system for special initial data (distribution functions which are analytic in the space variable, with compact support in velocity), a limit also called open-quotes quasineutral regimeclose quotes of the plasma, and the related oscillations of the electric field, with high frequency in time. 20 refs
Oscillations with laboratory neutrinos
Energy Technology Data Exchange (ETDEWEB)
Saitta, Biagio
2001-05-01
The status of searches for oscillations using neutrinos produced in the laboratory is reviewed. The most recent results from experiments approaching completion are reported and the potential capabilities of long baseline projects being developed in USA and Europe are considered and compared. The steps that should naturally follow this new generation of experiments are outlined and the impact of future facilities - such as neutrino factories or conventional superbeams - in precision measurements of elements of the neutrino mixing matrix is discussed.
International Nuclear Information System (INIS)
Atasoy, M.M.
2015-01-01
Aim: To define and assess the short-term clinical feasibility of fill and aspirate foam sclerotherapy (FAFS) for treating large superficial varicose veins concomitant to endovenous laser ablation (EVLA). Materials and methods: Twenty-seven patients who refused to have phlebectomies with great saphenous vein reflux and large superficial varicosities were included in the study. Both EVLA and FAFS were performed concomitantly. FAFS is a technique in which all or most of the bubbles and blood–foam mixture are removed from the targeted large varicose veins immediately after the foam has caused sufficient damage to the endothelial cells. Patients were reviewed 1 month and 6 months after the treatment. Improvement in the clinical, aetiological, anatomical, and pathological classification (CEAP), and clinical severity was graded using the revised venous clinical severity score (rVCSS) and cosmetic results were investigated at the 6 month visit. Results: Ablation of GSV was performed in 27 limbs in 27 patients (19 males, 70.3%; mean age 44 years; range 21–69 years). All patients had a technically successful FAFS treatment. The CEAP classification score, the rVCSS values, and the cosmetic results showed prominent improvement 6 months after the treatment. There were no significant complications, such as stroke, skin burns, necrosis, paresthesia, deep-vein thrombosis, or allergic reaction. None of the patients experienced neurological events. Conclusion: FAFS is a promising safe and effective technique for treating large superficial varicosities concomitant to EVLA of the truncal veins with excellent clinical results. Randomized prospective studies with larger series are required to compare the FAFS with ambulatory phlebectomy and standard foam sclerotherapy. - Highlights: • Fill and aspirate foam sclerotherapy (FAFS) is a easy and feasible alternative to the ambulatory phlebectomy for the treatment of large superficial varicose veins. • By using FAFS, foam can be
Directory of Open Access Journals (Sweden)
HP Pant
2015-06-01
Full Text Available BACKGROUND Varicosity of lower limb is a common problem in agricultural country like Nepal. Doppler ultrasound is a standard investigation modality for confirmation of diagnosis, evaluation of severity and venous mapping to plan treatment. We aim to find out the epidemiology, common pattern of incompetance, severity assessment by doppler and association of the important doppler variables with skin changes. METHODOLOGY Doppler venous study was done in 56 patients from june 2013 to july 2014. Patients with deep vein thrombosis and peripheral arterial disease were excluded. Altogether 56 patients, 96 limbs were studied. Data was entered in preformed proforma. Doppler study was conducted by senior radiologist with linear probes. Data was entered in SPSS software version 16 and statistical significance was calculated using chi square test. RESULTS Bilateral limb involvement was seen in 40 patients and unilateral in 16 patuents only. Skin related changes were seen in 58 limbs. Saphenofemoral junction incompetance was seen in 79(82.2% limbs and was most common pattern of incompetance. Overall, superficial veins were involved in 88(91.7% limbs and deep in 30(31.2% limbs. Prolonged duration of varicosity (>9 year (p=0.000, bilateral limb involvement(p=0.024, reflux in deep venous system(p=0.002, larger Greater Saphenous Vein (GSV size(p=0.003, prolonged duration of reflux(p=0.000 and perforator incompetence (p=0.002 were associated with skin changes. GSV diameter more than 7 mm was associated with reflux significantly (P=0.002. CONCLUSION Superficial vein incompetance is common pattern compared to deep venous system. Sapheno Femoral Junction (SFJ incompetance is the commonest pattern. Larger caliber of vein, prolonged duration of reflux, reflux in deep venous system and perforator insufficiency are significantly associated with skin changes.DOI: http://dx.doi.org/10.3126/jcmsn.v10i3.12770 Journal of College of Medical Sciences-Nepal, 2014, Vol-10, No-3
Hybrid Reactor Simulation of Boiling Water Reactor Power Oscillations
International Nuclear Information System (INIS)
Huang Zhengyu; Edwards, Robert M.
2003-01-01
Hybrid reactor simulation (HRS) of boiling water reactor (BWR) instabilities, including in-phase and out-of-phase (OOP) oscillations, has been implemented on The Pennsylvania State University TRIGA reactor. The TRIGA reactor's power response is used to simulate reactor neutron dynamics for in-phase oscillation or the fundamental mode of the reactor modal kinetics for OOP oscillations. The reactor power signal drives a real-time boiling channel simulation, and the calculated reactivity feedback is in turn fed into the TRIGA reactor via an experimental changeable reactivity device. The thermal-hydraulic dynamics, together with first harmonic mode power dynamics, is digitally simulated in the real-time environment. The real-time digital simulation of boiling channel thermal hydraulics is performed by solving constitutive equations for different regions in the channel and is realized by a high-performance personal computer. The nonlinearity of the thermal-hydraulic model ensures the capability to simulate the oscillation phenomena, limit cycle and OOP oscillation, in BWR nuclear power plants. By adjusting reactivity feedback gains for both modes, various oscillation combinations can be realized in the experiment. The dynamics of axially lumped power distribution over the core is displayed in three-dimensional graphs. The HRS reactor power response mimics the BWR core-wide power stability phenomena. In the OOP oscillation HRS, the combination of reactor response and the simulated first harmonic power using shaping functions mimics BWR regional power oscillations. With this HRS testbed, a monitoring and/or control system designed for BWR power oscillations can be experimentally tested and verified
Synchronization of mobile chaotic oscillator networks
International Nuclear Information System (INIS)
Fujiwara, Naoya; Kurths, Jürgen; Díaz-Guilera, Albert
2016-01-01
We study synchronization of systems in which agents holding chaotic oscillators move in a two-dimensional plane and interact with nearby ones forming a time dependent network. Due to the uncertainty in observing other agents' states, we assume that the interaction contains a certain amount of noise that turns out to be relevant for chaotic dynamics. We find that a synchronization transition takes place by changing a control parameter. But this transition depends on the relative dynamic scale of motion and interaction. When the topology change is slow, we observe an intermittent switching between laminar and burst states close to the transition due to small noise. This novel type of synchronization transition and intermittency can happen even when complete synchronization is linearly stable in the absence of noise. We show that the linear stability of the synchronized state is not a sufficient condition for its stability due to strong fluctuations of the transverse Lyapunov exponent associated with a slow network topology change. Since this effect can be observed within the linearized dynamics, we can expect such an effect in the temporal networks with noisy chaotic oscillators, irrespective of the details of the oscillator dynamics. When the topology change is fast, a linearized approximation describes well the dynamics towards synchrony. These results imply that the fluctuations of the finite-time transverse Lyapunov exponent should also be taken into account to estimate synchronization of the mobile contact networks.
Bloch oscillations in organic and inorganic polymers
Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; de Almeida Fonseca, Antonio Luciano; e Silva, Geraldo Magela
2017-04-01
The transport of polarons above the mobility threshold in organic and inorganic polymers is theoretically investigated in the framework of a one-dimensional tight-binding model that includes lattice relaxation. The computational approach is based on parameters for which the model Hamiltonian suitably describes different polymer lattices in the presence of external electric fields. Our findings show that, above critical field strengths, a dissociated polaron moves through the polymer lattice as a free electron performing Bloch oscillations. These critical electric fields are considerably smaller for inorganic lattices in comparison to organic polymers. Interestingly, for inorganic lattices, the free electron propagates preserving charge and spin densities' localization which is a characteristic of a static polaron. Moreover, in the turning points of the spatial Bloch oscillations, transient polaron levels are formed inside the band gap, thus generating a fully characterized polaron structure. For the organic case, on the other hand, no polaron signature is observed: neither in the shape of the distortion—those polaron profile signatures are absent—nor in the energy levels—as no such polaron levels are formed during the simulation. These results solve controversial aspects concerning Bloch oscillations recently reported in the literature and may enlighten the understanding about the charge transport mechanism in polymers above their mobility edge.
Zhao, Zi-Yuan; Zhang, Xiu-Jun; Li, Jun-Hai; Huang, Mei
2015-01-01
The aim of this study was to compare the results of high ligation and stripping of the great saphenous vein (GSV) trunk combined with foam sclerotherapy with conventional surgery for the treatment of superficial venous varicosities of the lower extremity. One hundred and thirty eight patients with primary or secondary superficial venous varicosities of the lower extremity were included. 60 underwent conventional surgery and 78 were treated with high ligation and stripping of the GSV trunk and foam sclerotherapy of GSV branches, spider veins, and reticular veins. Surgical time and amount of bleeding of single limb, recurrence of varicose vein, complications and patients satisfactory were recorded. Compared with the conventional surgery group, the GSV trunk stripping and foam sclerotherapy group had a significantly lower surgical time (P 0.05). GSV trunk stripping and foam sclerotherapy group at a 6 months of follow up had a higher recurrence rate of varicosity as compared to the conventional surgery group (P sclerotherapy prior to conventional surgery for patients with superficial venous varicosities of the lower extremity with a shorter surgical time, fewer bleeding, duration of hospital stays and higher patients satisfactory scores. PMID:26221338
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.
2007-01-01
A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...... contralateral to stimulus side and additionally an unexpected 20 Hz activity was observed slightly lateralized in the frontal central region. The gamma phase locking may be a manifestation of early somatosensory feature integration. The analyses suggest that the high frequency activity consists of two distinct...
Neutrino oscillations at LAMPF
International Nuclear Information System (INIS)
Carlini, R.; Choi, C.; Donohue, J.
1985-01-01
Work at Argonne continues on the construction of the neutrino oscillation experiment (E645). Construction of detector supports and active shield components were completed at the Provo plant of the principal contractor for the project (the Pittsburgh-Des Moines Corporation). Erection of the major experimental components was completed at the LAMPF experimental site in mid-March 1985. Work continues on the tunnel which will house the detector. Construction of detector components (scintillators and proportional drift tubes) is proceeding at Ohio State University and Louisiana State University. Consolidation of these components into the 20-ton neutrino detector is beginning at LAMPF
Andronov, Aleksandr Aleksandrovich; Vitt, Aleksandr Adolfovich
1966-01-01
Theory of Oscillators presents the applications and exposition of the qualitative theory of differential equations. This book discusses the idea of a discontinuous transition in a dynamic process. Organized into 11 chapters, this book begins with an overview of the simplest type of oscillatory system in which the motion is described by a linear differential equation. This text then examines the character of the motion of the representative point along the hyperbola. Other chapters consider examples of two basic types of non-linear non-conservative systems, namely, dissipative systems and self-
Energy Technology Data Exchange (ETDEWEB)
Meneses, Luis, E-mail: lmeneseq@gmail.com; Fava, Mario; Diaz, Pia; Andia, Marcelo [Pontificia Universidad Catolica de Chile, Radiology Department and Biomedical Imaging Center (Chile); Tejos, Cristian; Irarrazabal, Pablo [Pontificia Universidad Catolica de Chile, Biomedical Imaging Center (Chile); Uribe, Sergio, E-mail: suribe@med.puc.cl [Pontificia Universidad Catolica de Chile, Radiology Department and Biomedical Imaging Center (Chile)
2013-02-15
We present our experience with embolization of incompetent pelvic veins (IPV) in women with recurrence of varicose veins (VV) in lower limbs, as well as symptoms of pelvic congestion syndrome (PCS), after first surgery. In addition, we evaluated the effects of embolization in decreasing the symptoms of VV before surgery as well as its effects on PCS symptoms. We included 10 women who had consulted a vascular surgeon because of recurrent VV in lower limbs after surgery. All of these patients were included in the study because they also had symptoms of PCS, probably due to IPV. In patients who had confirmed IPV, we performed embolization before a second surgery. VV and PCS were assessed before and at 3 months after embolization (before the second surgery) using a venous clinical severity score (VCSS) and a visual analog pain scale (VAS), respectively. Patients were controlled between 3 and 6 months after embolization. Paired Student t test analysis was used for comparing data before and after embolization. Fifteen vein segments in 10 women were suitable for embolization. There was a significant (p < 0.001) decrease of VCSS after embolization, and recurrence of VV was not detected within a period of 6 months. There was also significant (p < 0.01) relief of chronic pelvic pain related to PCS evaluated using VAS at 3 months after embolization. Embolization decreases the risk of VV recurrence after surgery and also improves PCS symptoms in women with VV in lower limbs and IPV.
International Nuclear Information System (INIS)
Meneses, Luis; Fava, Mario; Diaz, Pía; Andía, Marcelo; Tejos, Cristian; Irarrazabal, Pablo; Uribe, Sergio
2013-01-01
We present our experience with embolization of incompetent pelvic veins (IPV) in women with recurrence of varicose veins (VV) in lower limbs, as well as symptoms of pelvic congestion syndrome (PCS), after first surgery. In addition, we evaluated the effects of embolization in decreasing the symptoms of VV before surgery as well as its effects on PCS symptoms. We included 10 women who had consulted a vascular surgeon because of recurrent VV in lower limbs after surgery. All of these patients were included in the study because they also had symptoms of PCS, probably due to IPV. In patients who had confirmed IPV, we performed embolization before a second surgery. VV and PCS were assessed before and at 3 months after embolization (before the second surgery) using a venous clinical severity score (VCSS) and a visual analog pain scale (VAS), respectively. Patients were controlled between 3 and 6 months after embolization. Paired Student t test analysis was used for comparing data before and after embolization. Fifteen vein segments in 10 women were suitable for embolization. There was a significant (p < 0.001) decrease of VCSS after embolization, and recurrence of VV was not detected within a period of 6 months. There was also significant (p < 0.01) relief of chronic pelvic pain related to PCS evaluated using VAS at 3 months after embolization. Embolization decreases the risk of VV recurrence after surgery and also improves PCS symptoms in women with VV in lower limbs and IPV.
Directory of Open Access Journals (Sweden)
LUCIANA MARINS CAVALCANTI
Full Text Available ABSTRACT Objective: to evaluate the efficacy of Bacterial Cellulose (BC membrane dressings in the treatment of lower limb venous ulcers. Methods: we carried out a prospective, randomized, controlled study of 25 patients with chronic venous ulcer disease in the lower limbs from the Angiology and Vascular Surgery Service of the Federal University of Pernambuco Hospital and from the Salgado Polyclinic of the County Health Department, Caruaru, Pernambuco. We randomly assigned patients to two groups: control group, receiving dressings with triglyceride oil (11 patients and experimental group, treated with BC membrane (14 patients. We followed the patients for a period of 120 days. Results: There was a reduction in the wound area in both groups. There were no infections or reactions to the product in any of the groups. Patients in the BC group showed decreased pain and earlier discontinuation of analgesic use. Conclusion: BC membrane can be used as a dressing for the treatment of varicose ulcers of the lower limbs.
Cirurgia de varizes em regime de mutirão A task force for varicose vein surgery
Directory of Open Access Journals (Sweden)
Carlos Eduardo Virgini-Magalhães
2007-09-01
estágios moderados da doença, especialmente nas classes C2 e C3 da CEAP, e que requerem cirurgias de médio e grande porte para o tratamento de suas patologias.BACKGROUND: Varicose vein surgery of the lower limbs is one of the most frequent procedures carried out in the Brazilian public health system (Sistema Único de Saúde, especially during task forces focused on elective surgeries. However, detailed information on the results of such initiatives are absent in the literature, particularly with regard to the population that benefits from the task forces. OBJECTIVES: To present and discuss the profile of patients operated on during a task force for varicose vein surgery carried out in a public health institution. METHODS: The patients were selected from a database organized by the Brazilian Health Ministry for the program of elective surgeries, and they had no previous link with the hospital institution. A protocol for objective evaluation with the clinical data and demographic profile of the patients was applied. The patients were staged according to CEAP classification. RESULTS: From September 2005 to January 2006, 100 patients (106 procedures underwent surgery, females being predominant (85% of the cases. Mean age was 35±9.8 years. Predominant schooling level among patients was primary school (53%. C2 (49.5% and C3 (39% were the most frequent CEAP classes in the clinical evaluation of lower limbs. A total of 106 surgeries was performed (100 patients. The preferred anesthetic technique was block anesthesia (93% of the procedures. Six patients were submitted to two different procedures due to great volume of lower limb varicose veins; 33 patients were submitted to internal saphenous vein stripping (four cases of segmental saphenous vein stripping; and eight patients were submitted to bilateral total saphenous vein stripping. CONCLUSION: Profile of the population that benefited from the task force for varicose vein surgeries was: young symptomatic female patients
Recek, Cestmir
2016-12-01
Varicose vein disease is characterized by tenacious tendency to recur. Measures recommended to prevent recurrences (flush ligation at the saphenofemoral junction, removal of incompetent great saphenous vein in the thigh, and insertion of mechanical barriers in the fossa ovalis) did not succeed in preventing recurrence. Reflux recurrence is triggered by the hemodynamic phenomenon called hemodynamic paradox. Abolition of saphenous reflux removes the hemodynamic disturbance of any degree of severity but at the same time it releases the pathological process leading to recurrent reflux. This process is induced by drainage of venous blood from incompetent superficial thigh veins into deep lower leg veins during calf pump activity, which evokes the development of ambulatory pressure gradient between the femoral vein and incompetent segments of the saphenous system in the thigh. The pressure gradient sets off biophysical and biochemical events inducing recurrent reflux. The designed therapeutic strategy consists of reliable abolition of saphenous reflux and of hindering the pathological drainage of venous blood at the knee level in order to preclude development of the hemodynamic preconditions for reflux recurrence. In this way, the dividing line of the ambulatory pressure gradient would be kept below the knee, as is the case with healthy people.
Liang, Yan; Jia, Yusheng; Zhang, Zhidong; Xu, Futian; Yang, Qian; Yan, Jianzhang; Gao, Dengpeng; Liu, Liheng; Zhang, Ruijian; Guo, Yubo; Zhang, Qingfu; Li, Yong
2015-01-01
Aim: To investigate the efficacy and early postoperative morbidity of a novel endovenous laser ablation (IEVLA) strategy of treatment of the great saphenous vein (GSV) with difficulty of wire placement. Methods: Sixty patients with serious GSV incompetence in 73 limbs were randomized into two treatment groups: Group 1 underwent traditional endovenous laser ablation (TEVLA) surgery and group 2 received IEVLA. Local pain, ecchymosis, induration, paraesthesia in treated regions, thrombotic diseases, vein diameter, treated vein length, delivered energy, operation duration, success rate in placement of the laser fiber and venous clinical severity (VCS) scores were recorded for both group. Follow-up were conducted on the 2nd day, 7th day, and 1st, 2nd, 3rd and 6th month postoperatively. Results: In group 1, induration was present in 18 cases, ecchymosis in 19, paraesthesia in 9, pulmonary embolism (PE) in 1 case, and deep vein thrombus (DVT) in 3. While in group 2, induration present in 29, ecchymosis in 23, paraesthesia in 17 with and no patients were complicated with PE or DVT. Although no difference in improvement of VCS score existed between the two groups at each follow-up time point, group 2 had significantly shorter operation time and higher success rate (P < 0.05). Conclusion: IEVLA is a more effective and safe technique for treatment of serious GSV varicosities with difficulty of wire placement. PMID:26131173
Brain Oscillations, Hypnosis, and Hypnotizability
Jensen, Mark P.; Adachi, Tomonori; Hakimian, Shahin
2014-01-01
In this article, we summarize the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, and are usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. Here we propose that it is this role that may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis; specifically that theta oscillations may facilitate, and that changes in gamma activity observed with hypnosis may underlie, some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis, and for enhancing response to hypnotic treatments. PMID:25792761
Brain Oscillations, Hypnosis, and Hypnotizability.
Jensen, Mark P; Adachi, Tomonori; Hakimian, Shahin
2015-01-01
This article summarizes the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. The authors propose that this role may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis, specifically, that the increases in theta oscillations and changes in gamma activity observed with hypnosis may underlie some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis and for enhancing response to hypnotic treatments.
Bounded-oscillation Pushdown Automata
Directory of Open Access Journals (Sweden)
Pierre Ganty
2016-09-01
Full Text Available We present an underapproximation for context-free languages by filtering out runs of the underlying pushdown automaton depending on how the stack height evolves over time. In particular, we assign to each run a number quantifying the oscillating behavior of the stack along the run. We study languages accepted by pushdown automata restricted to k-oscillating runs. We relate oscillation on pushdown automata with a counterpart restriction on context-free grammars. We also provide a way to filter all but the k-oscillating runs from a given PDA by annotating stack symbols with information about the oscillation. Finally, we study closure properties of the defined class of languages and the complexity of the k-emptiness problem asking, given a pushdown automaton P and k >= 0, whether P has a k-oscillating run. We show that, when k is not part of the input, the k-emptiness problem is NLOGSPACE-complete.
Dynamics of microcapsules in oscillating shear flow
Zhao, Mengye; Bagchi, Prosenjit
2011-11-01
We present a three-dimensional numerical study on the dynamics of deformable capsules in sinusoidally oscillating shear flow. We consider capsules of spherical and oblate spheroid resting shapes. For spherical resting shapes, we find an identical deformation response during positive and negative vorticities. However, the deformation response becomes unequal and shows complex behavior for nonspherical resting shapes. The average elongation is higher in the retarding phase of the shear flow than in the accelerating phase. Primarily two types of dynamics are observed for nonspherical shapes: a clockwise/counter-clockwise swinging motion in response to the altering flow direction that occurs at both high and low values of shear rate amplitudes, and a continuous/unidirectional tumbling motion that occurs at intermediate values. The unidirectional tumbling motion occurs despite the fact that the time-average vorticity is zero. Such a tumbling motion is accompanied by a continuous tank-treading motion of the membrane in the opposite direction. We obtain phase diagram that shows existence of two critical shear rates and two oscillation frequencies. The unidirectional tumbling motion occurs in the intermediate range, and the clockwise/counter-clockwise swinging motion occurs otherwise. We also find that the dynamics is highly sensitive to the initial condition. A swinging is generally observed when the capsule is released aligned with the extensional or compressional axis of the shear flow, and a tumbling is observed otherwise. These results suggest the possibility of chaotic behavior of cells in time-dependent flows. We provide explanations of such complex dynamics by analyzing the coupling between the shape and angular oscillation and the imposed flow oscillation.
An Artificial Muscle Ring Oscillator
O’Brien, Benjamin Marc; Anderson, Iain Alexander
2012-01-01
Dielectric elastomer artificialmuscles have great potential for the creation of novel pumps, motors, and circuitry. Control of these devices requires an oscillator, either as a driver or clock circuit, which is typically provided as part of bulky, rigid, and costly external electronics. Oscillator circuits based on piezo-resistive dielectric elastomer switch technology provide a way to embed oscillatory behavior into artificial muscle devices. Previous oscillator circuits were not digital, ab...
Harmonic oscillator in an elastic medium with a spiral dislocation
Maia, A. V. D. M.; Bakke, K.
2018-02-01
We investigate the behaviour of a two-dimensional harmonic oscillator in an elastic medium that possesses a spiral dislocation (an edge dislocation). We show that the Schrödinger equation for harmonic oscillator in the presence of a spiral dislocation can be solved analytically. Further, we discuss the effects of this topological defect on the confinement to a hard-wall confining potential. In both cases, we analyse if the effects of the topology of the spiral dislocation gives rise to an Aharonov-Bohm-type effect for bound states.
Predicting charmonium and bottomonium spectra with a quark harmonic oscillator
Norbury, J. W.; Badavi, F. F.; Townsend, L. W.
1986-01-01
The nonrelativistic quark model is applied to heavy (nonrelativistic) meson (two-body) systems to obtain sufficiently accurate predictions of the spin-averaged mass levels of the charmonium and bottomonium spectra as an example of the three-dimensional harmonic oscillator. The present calculations do not include any spin dependence, but rather, mass values are averaged for different spins. Results for a charmed quark mass value of 1500 MeV/c-squared show that the simple harmonic oscillator model provides good agreement with experimental values for 3P states, and adequate agreement for the 3S1 states.
Microwave phase locking of Josephson-junction fluxon oscillators
DEFF Research Database (Denmark)
Salerno, M.; Samuelsen, Mogens Rugholm; Filatrella, G.
1990-01-01
Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two-dimensional fun......Application of the classic McLaughlin-Scott soliton perturbation theory to a Josephson-junction fluxon subjected to a microwave field that interacts with the fluxon only at the junction boundaries reduces the problem of phase locking of the fluxon oscillation to the study of a two...
Oscillation in Pest Population and Its Management: A Mathematical Study
Directory of Open Access Journals (Sweden)
Samit Bhattacharyya
2013-01-01
Full Text Available We study the role of predation dynamics in oscillation of pest population in insect ecology. A two-dimensional pest control model (under the use of insecticides with time delay in predation is considered in this paper. By the Hopf bifurcation theory, we prove the existence of the stable oscillation of the system. We also consider the economic viability of the control process. First we improve the Pontryagin maximum principle (PMP where the delay in the system is sufficiently small and control function is linear, and then we apply the improved version of PMP to perform the optimal analysis of the pest control model as a special case.
Nanoscale relaxation oscillator
Zettl, Alexander K.; Regan, Brian C.; Aloni, Shaul
2009-04-07
A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.
Unstable oscillators based hyperchaotic circuit
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.
1999-01-01
A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...
Spatial computation with gamma oscillations
Engelhard, Ben; Vaadia, Eilon
2014-01-01
Gamma oscillations in cortex have been extensively studied with relation to behavior in both humans and animal models; however, their computational role in the processing of behaviorally relevant signals is still not clear. One oft-overlooked characteristic of gamma oscillations is their spatial distribution over the cortical space and the computational consequences of such an organization. Here, we advance the proposal that the spatial organization of gamma oscillations is of major importance for their function. The interaction of specific spatial distributions of oscillations with the functional topography of cortex enables select amplification of neuronal signals, which supports perceptual and cognitive processing. PMID:25249950
The Duffing oscillator with damping
DEFF Research Database (Denmark)
Johannessen, Kim
2015-01-01
An analytical solution to the differential equation describing the Duffing oscillator with damping is presented. The damping term of the differential equation and the initial conditions satisfy an algebraic equation, and thus the solution is specific for this type of damping. The nonlinear term....... It is established that the period of oscillation is shorter compared to that of a linearized model but increasing with time and asymptotically approaching the period of oscillation of the linear damped model. An explicit expression for the period of oscillation has been derived, and it is found to be very accurate....
Oscillation criteria for a class of partial functional-differential equations of higher order
Directory of Open Access Journals (Sweden)
Tariel Kiguradze
2002-01-01
Full Text Available Higher order partial differential equations with functional arguments including hyperbolic equations and beam equations are studied. Sufficient conditions are derived for every solution of certain boundary value problems to be oscillatory in a cylindrical domain. Our approach is to reduce the multi-dimensional oscillation problem to a one-dimensional problem for higher order functional differential inequalities.
Quasi quantum group covariant q-oscillators
International Nuclear Information System (INIS)
Schomerus, V.
1992-05-01
If q is a p-th root of unity there exists a quasi-co-associative truncated quantum group algebra U T q (sl 2 ) whose indecomposable representations are the physical representations of U q (sl 2 ), whose co-product yields the truneated tensor product of physical representations of U q (sl 2 ), and whose R-matrix satisfies quasi Yang Baxter equations. For primitive p-th roots q, we consider a 2-dimensional q-oscillator which admits U T q (sl 2 ) as a symmetry algebra. Its wave functions lie in a space F T q of 'functions on the truncated quantum plane', i.e. of polynomials in noncommuting complex coordinate functions z a , on which multiplication operators Z a and the elements of U T q (sl 2 ) can act. This illustrates the concept of quasi quantum planes. Due to the truncation, the Hilbert space of states is finite dimensional. The subspaces F T(n) of monomials in x a of n-th degree vanish for n ≥ p-1, and F T(n) carries the 2J+1 dimensional irreducible representation of U T q (sl 2 ) if n=2J, J=0, 1/2, ... 1/2(p-2). Partial derivatives δ a are introduced. We find a *-operation on the algebra of multiplication operators Z i and derivatives δ b such that the adjoints Z * a act as differentiation on the truncated quantum plane. Multiplication operators Z a ('creation operators') and their adjoints ('annihilation operators') obey q -1/2 -commutation relations. The *-operation is used to determine a positive definite scalar product on the truncated quantum plane F T q . Some natural candidates of Hamiltonians for the q-oscillators are determined. (orig./HSI)
Coronal Waves and Oscillations
Directory of Open Access Journals (Sweden)
Nakariakov Valery M.
2005-07-01
Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.
Hyperchaos in coupled Colpitts oscillators
DEFF Research Database (Denmark)
Cenys, Antanas; Tamasevicius, Arunas; Baziliauskas, Antanas
2003-01-01
The paper suggests a simple solution of building a hyperchaotic oscillator. Two chaotic Colpitts oscillators, either identical or non-identical ones are coupled by means of two linear resistors R-k. The hyperchaotic output signal v(t) is a linear combination, specifically the mean of the individual...
Oscillating solitons in nonlinear optics
Indian Academy of Sciences (India)
... are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers.
The Wien Bridge Oscillator Family
DEFF Research Database (Denmark)
Lindberg, Erik
2006-01-01
A tutorial in which the Wien bridge family of oscillators is defined and investigated. Oscillators which do not fit into the Barkhausen criterion topology may be designed. A design procedure based on initial complex pole quality factor is reported. The dynamic transfer characteristic...
Mechanical Parametric Oscillations and Waves
Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.
2013-01-01
Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…
Stochastic and Chaotic Relaxation Oscillations
Grasman, J.; Roerdink, J.B.T.M.
1988-01-01
For relaxation oscillators stochastic and chaotic dynamics are investigated. The effect of random perturbations upon the period is computed. For an extended system with additional state variables chaotic behavior can be expected. As an example, the Van der Pol oscillator is changed into a
Oscillator strengths for neutral technetium
International Nuclear Information System (INIS)
Garstang, R.H.
1981-01-01
Oscillator strengths have been calculated for most of the spectral lines of TcI which are of interest in the study of stars of spectral type S. Oscillator strengths have been computed for the corresponding transitions in MnI as a partial check of the technetium calculations
Quasi Periodic Oscillations in Blazars
Indian Academy of Sciences (India)
2016-01-27
Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 35; Issue 3. Quasi Periodic Oscillations in Blazars ... Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important ...
Complex dynamical invariants for two-dimensional complex potentials
Indian Academy of Sciences (India)
Abstract. Complex dynamical invariants are searched out for two-dimensional complex poten- tials using rationalization method within the framework of an extended complex phase space characterized by x = x1 + ip3, y = x2 + ip4, px = p1 + ix3, py = p2 + ix4. It is found that the cubic oscillator and shifted harmonic oscillator ...
Oscillating nonlinear acoustic shock waves
DEFF Research Database (Denmark)
Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth
2016-01-01
We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....
Scattering of electromagnetic waves into plasma oscillations via plasma particles
International Nuclear Information System (INIS)
Lin, A.T.; Dawson, J.M.
1975-01-01
A plasma subjected to an intense electromagnetic wave can exhibit a large number of parametric instabilities. An interesting example which has received little attention is the decay of the electromagnetic wave into a plasma oscillation with the excess energy and momentum being carried off by electrons. This process has been simulated on a one-and-two-halves dimensional electromagnetic code. The incident electromagnetic wave had a frequency near the plasma frequency so that decay into a plasma oscillation and a backscattered electromagnetic wave was excluded. As expected, the threshold for this instability was very large , so it is unlikely that this instability is competitive in most laser plasmas. Nevertheless, the physical mechanism involved provides a means for absorption of laser light and acceleration of particles in a plasma containing large amplitude plasma oscillations
Analysis of reactor power oscillation based on nonlinear dynamic theory
International Nuclear Information System (INIS)
Suzudo, Tomoaki
1994-07-01
Reactor power oscillations are discussed based on nonlinear dynamic theory with reference to stability problem of boiling water reactors (BWRs). The reactor noise from an actual plant is, firstly, analyzed by a method originally used for the analysis of chaotic phenomenon. The results show that this method gives better dynamic descriptor of oscillatory motion than those from previous methods, and that it is applicable to real-time monitoring system of the reactor core. Next, the low-dimensional phenomenological model of BWR power oscillation is analytically studied using bifurcation theory, a branch of nonlinear dynamic theory. From this analysis are derived explicit expressions for the steady state's linear stability and weak stability not given by numerical analyses, and the qualitative properties of the power oscillation can be better understood. (author)
Zolotukhin, Igor A; Seliverstov, Evgeny I; Zakharova, Elena A; Kirienko, Alexander I
2017-10-01
Objective To establish an effect of isolated phlebectomy in patients with incompetent great saphenous vein (Ambulatory Selective Varices Ablation under Local anesthesia (ASVAL) procedure) on the reflux and diameter of the trunk and to assess recurrence rate of varicose veins at one year. Material and methods We conducted a prospective study on patients with primary varicose veins and with C2 or C2,3 or C2,3,4 or C2,4 classes of chronic venous disease and great saphenous vein incompetence. The study included 67 patients (51 women and 16 men; 75 limbs in total). Age varied from 17 to 71 years; mean age was 46.8 years (SD 13.9). We recorded the presence or absence of reflux in the great saphenous vein with duplex ultrasound before and after surgery. The recurrence of varicose veins was evaluated at 12 months. All the patients underwent isolated phlebectomy with preservation of incompetent great saphenous vein (ASVAL procedure) under local anesthesia. Results At one year after removing of tributaries of the incompetent trunk, 66% of them were competent. Reflux persisted in 17% of great saphenous veins with reflux above mid-thigh and in 61% of trunks with reflux extended below the mid-thigh (p = 0.0004). The diameter of all the veins decreased significantly no matter reflux disappeared or not. Varicose veins reoccurred in 13.5% cases. In 6.5% of limbs with a reflux above the mid-thigh, the recurrence was registered at one year, while in the limbs with the reflux below the mid-thigh at a baseline, the recurrence rate was 25% (p = 0.036). Conclusion Isolated phlebectomy with a preservation of incompetent great saphenous vein leads to disappearance of reflux in a majority of cases and to significant decrease of vein diameter in all the cases. ASVAL procedure could be considered as a less aggressive and less expensive approach in selected cases. Clear indications for isolated phlebectomy need to be established.
Raffetto, Joseph D; Khalil, Raouf A
2011-08-01
Saponosides (horse chestnut seed extract, escin) and flavonoids (diosmin, Daflon 500, Servier, France) exhibit venotonic properties that have been utilized in treatment of varicose veins. However, the cellular mechanisms underlying the venotonic properties of escin and diosmin are unclear. Because Ca(2+) is a major regulator of venous smooth muscle (VSM) function, we tested the hypothesis that escin and diosmin promote Ca(2+)-dependent venous contraction. Rings of inferior vena cava (IVC) from male rats were suspended in a tissue bath for measurement of isometric contraction. Following control contraction to 96 mM KCl, the effects of escin and diosmin (10(-10) to 10(-4) M) on vein contraction were measured. To test the role of intracellular Ca(2+) release, the vein response to escin and diosmin was measured in Ca(2+)-free (2mM EGTA) Krebs. To test for Ca(2+)-dependent effects, IVC segments were pretreated with escin or diosmin (10(-4) M) in 0 Ca(2+) Krebs, then extracellular CaCl(2) (0.1, 0.3, 0.6, 1, 2.5 mM) was added and the [Ca(2+)](e)-contraction relationship was constructed. To test for synergistic effects of diosmin, IVC segments were pretreated with diosmin (10(-4) M), then stimulated with KCl (16-96 mM) or escin (10(-10) to 10(-4) M) and vein contraction was measured. Contraction data were presented as mg/mg tissue (means ± SEM). In IVC segments incubated in normal Krebs (2.5 mM Ca(2+)), escin caused concentration-dependent contraction (max 104.3 ± 19.6 at 10(-4) M). Escin-induced contraction was not a rigor state, because after washing with Krebs, the veins returned to a relaxed state. In Ca(2+)-free Krebs, there was essentially no contraction to escin. In escin-treated veins incubated in 0 Ca(2+) Krebs, stepwise addition of extracellular CaCl(2) caused corresponding increases in contraction (max 80.0 ± 11.1 at 2.5 mM). In the absence of escin, the α-adrenergic agonist phenylephrine (PHE, 10(-5) M), angiotensin II (AngII, 10(-6) M), and membrane
Raffetto, Joseph D.; Khalil, Raouf A.
2011-01-01
Background Saponosides (horse chestnut seed extract, escin) and flavonoids (diosmin, Daflon 500) exhibit venotonic properties that have been utilized in treatment of varicose veins. However, the cellular mechanisms underlying the venotonic properties of escin and diosmin are unclear. Because Ca2+ is a major regulator of venous smooth muscle (VSM) function, we tested the hypothesis that escin and diosmin promote Ca2+-dependent venous contraction. Methods Rings of inferior vena cava (IVC) from male rats were suspended in a tissue bath for measurement of isometric contraction. Following control contraction to 96 mM KCl, the effects of escin and diosmin (10−10 to 10−4 M) on vein contraction were measured. To test the role of intracellular Ca2+ release, the vein response to escin and diosmin was measured in Ca2+-free (2mM EGTA) Krebs. To test for Ca2+-dependent effects, IVC segments were pretreated with escin or diosmin (10−4 M) in 0 Ca2+ Krebs, then extracellular CaCl2 (0.1, 0.3, 0.6, 1, 2.5 mM) was added and the [Ca2+]e-contraction relationship was constructed. To test for synergistic effects of diosmin, IVC segments were pretreated with diosmin (10−4 M) then stimulated with KCl (16 to 96 mM) or escin (10−10 to 10−4 M) and vein contraction was measured. Contraction data were presented as mg/mg tissue (means±SEM). Results In IVC segments incubated in normal Krebs (2.5 mM Ca2+), escin caused concentration-dependent contraction (max 104.3±19.6 at 10−4 M). Escin-induced contraction was not a rigor state, because after washing with Krebs the veins returned to a relaxed state. In Ca2+-free Krebs, there was essentially no contraction to escin. In escin-treated veins incubated in 0 Ca2+ Krebs, stepwise addition of extracellular CaCl2 caused corresponding increases in contraction (max 80.0±11.1 at 2.5 mM). In the absence of escin, the α-adrenergic agonist phenylephrine (PHE, 10−5 M), angiotensin II (AngII, 10−6 M), and membrane depolarization by KCl (96 m
Meneses, Luis; Fava, Mario; Diaz, Pía; Andía, Marcelo; Tejos, Cristian; Irarrazaval, Pablo; Irarrazabal, Pablo; Uribe, Sergio
2013-02-01
We present our experience with embolization of incompetent pelvic veins (IPV) in women with recurrence of varicose veins (VV) in lower limbs, as well as symptoms of pelvic congestion syndrome (PCS), after first surgery. In addition, we evaluated the effects of embolization in decreasing the symptoms of VV before surgery as well as its effects on PCS symptoms. We included 10 women who had consulted a vascular surgeon because of recurrent VV in lower limbs after surgery. All of these patients were included in the study because they also had symptoms of PCS, probably due to IPV. In patients who had confirmed IPV, we performed embolization before a second surgery. VV and PCS were assessed before and at 3 months after embolization (before the second surgery) using a venous clinical severity score (VCSS) and a visual analog pain scale (VAS), respectively. Patients were controlled between 3 and 6 months after embolization. Paired Student t test analysis was used for comparing data before and after embolization. Fifteen vein segments in 10 women were suitable for embolization. There was a significant (p < 0.001) decrease of VCSS after embolization, and recurrence of VV was not detected within a period of 6 months. There was also significant (p < 0.01) relief of chronic pelvic pain related to PCS evaluated using VAS at 3 months after embolization. Embolization decreases the risk of VV recurrence after surgery and also improves PCS symptoms in women with VV in lower limbs and IPV.
Suhartono, R.; Irfan, W.; Wangge, G.; Moenadjat, Y.; Destanto, W. I.
2017-08-01
Endovenous ablation has been performed for varicose veins of the limbs in Indonesia since 2010. Endovenous laser ablation (EVLA) therapy has been performed in Cipto Mangunkusumo Hospital (RSCM) in Jakarta, and mechanochemical ablation (MOCA) has been conducted in Fatmawati Hospital. This was a descriptive analytical study, with a cross-sectional design to analyze post-ablation recanalization after MOCA and EVLA procedures. Patients who had undergone MOCA or EVLA treatment were interviewed 3-18 months after the procedures. All the patients underwent vascular ultrasonography (USG) of the operated limb to assess recanalization. Secondary presurgery data were obtained from the patients’ from patients’ medical records. The clinical characteristics of the subjects were recorded to compare the potential correlation between these characteristics and recanalization post-MOCA and EVLA procedures. All the data were analyzed using SPSS ver. 20.0. The study consisted of 43 limbs: 24 treated by MOCA and 19 treated by EVLA. Most subjects in the MOCA group were 7 mm in 13/19 extremities. In the MOCA group, total recanalization occurred in 2/24 extremities, and partial recanalization occurred in 8/24 extremities. In the EVLA group, total recanalization occurred in 1/19 extremities, and partial recanalization occurred in 3/19 extremities. The association between the clinical characteristics of the patients and recanalization was not statistically significant (p > 0.05). The recanalization tendency was higher in the MOCA group than in the EVLA group. Although there was no statistically significant association between the clinical characteristics of the patients and recanalization, the largest diameter of the VSM presurgery (>7 mm) was higher in 3/4 extremities in the MOCA group, as compared to 3/13 extremities in the EVLA group.
Paravastu, Sharath Chandra Vikram; Horne, Margaret; Dodd, P Dominic F
2016-11-29
Short (or small) saphenous vein (SSV) varices occur as a result of an incompetent sapheno-popliteal junction, where the SSV joins the popliteal vein, resulting in reflux in the SSV; they account for about 15% of varicose veins. Untreated varicose veins may sometimes lead to ulceration of the leg, which is difficult to manage. Traditionally, treatment was restricted to surgery or conservative management. Since the 1990s, however, a number of minimally invasive techniques have been developed; these do not normally require a general anaesthetic, are day-case procedures with a quicker return to normal activities and avoid the risk of wound infection which may occur following surgery. Nerve injury remains a risk with thermal ablation, but in cases where it does occur, the injury tends to be transient. To compare the effectiveness of endovenous laser ablation (EVLA), radiofrequency ablation (RFA) and ultrasound-guided foam sclerotherapy (UGFS) versus conventional surgery in the treatment of SSV varices. The Cochrane Vascular Information Specialist searched the Specialised Register (last searched 17 March 2016) and the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 2). We searched clinical trials databases for details of ongoing or unpublished studies. We considered all randomised controlled trials (RCTs) comparing EVLA, endovenous RFA or UGFS with conventional surgery in the treatment of SSV varices for inclusion. We independently reviewed, assessed and selected trials that met the inclusion criteria; any disagreements were resolved by discussion. We extracted data and used the Cochrane's tool for assessing risk of bias. When the data permitted, we performed either fixed-effect meta-analyses with odds ratios (ORs) and 95% confidence intervals (CIs) or random-effects meta-analyses where there was moderate to significant heterogeneity. We identified three RCTs, all of which compared EVLA with surgery; one also compared UGFS with surgery. There were no
Truong Van, Gia; Kang, Hyun Wook
2017-02-01
For last two decades, endovenous laser therapy (EVLT) is one of the most widely accepted surgical options for treating incompetent great and small saphenous veins. However, due to excessive heating during EVLT, the major complications include pain and burning that often increase the risk of dermatitis disease. The aim of the current study was to quantitatively compare commercially-available radial fibers with newly-developed diffusing applicators for 1470 nm-EVLA in terms of temperature elevation and vein deformation. Rabbit veins were used as an ex vivo model for EVLA. A 5-W 1470 nm laser system in conjunction with the radial and diffusing fibers was employed to thermally coagulate the venous tissue. A goniometric measurement validated uniform and isotropic distribution of laser light in polar and longitudinal directions (i.e., normalized intensity = 0.84±0.08). The diffusing applicator induced a 20 % lower maximum temperature than the radial fiber did (maximum temperature = 79.2 °C for radial vs. 63.3 °C for diffusing). Due to higher irradiance, the radial fiber was associated with a transient temperature change of 5.9 °C/s, which was 1.5-fold faster than the diffusing applicator (i.e., 2.4 °C/s). However, the degree of cross-sectional area reduction in the veins was almost comparable for both the fibers (i.e., 53% for radial vs. 48% for diffusing). Due to longer irradiation length, the diffusing applicator demonstrated wider treatment coverage and less fiber speed-dependent. On account of easy pullback technique and uniform thermal effect, the proposed cylindrically diffusing applicator can be a feasible optical device to effectively treat varicose veins. Further in vivo studies will be performed to identify the complete removal of the vein disease and healing response of the venous tissue.
Oscillations of atomic nuclei in crystals
Vdovenkov, V. A.
2002-01-01
Oscillations of atomic nuclei in crystals are considered in this paper. It is shown that elastic nuclei oscillations relatively electron envelops (inherent, I-oscillations) and waves of such oscillations can exist in crystals at adiabatic condition. The types and energy quantums of I-oscillations for different atoms are determined. In this connection the adiabatic crystal model is offered. Each atom in the adiabatic model is submitted as I-oscillator whose stationary oscillatory terms are sho...
Pacemakers in large arrays of oscillators with nonlocal coupling
Jaramillo, Gabriela; Scheel, Arnd
2016-02-01
We model pacemaker effects of an algebraically localized heterogeneity in a 1 dimensional array of oscillators with nonlocal coupling. We assume the oscillators obey simple phase dynamics and that the array is large enough so that it can be approximated by a continuous nonlocal evolution equation. We concentrate on the case of heterogeneities with positive average and show that steady solutions to the nonlocal problem exist. In particular, we show that these heterogeneities act as a wave source. This effect is not possible in 3 dimensional systems, such as the complex Ginzburg-Landau equation, where the wavenumber of weak sources decays at infinity. To obtain our results we use a series of isomorphisms to relate the nonlocal problem to the viscous eikonal equation. We then use Fredholm properties of the Laplace operator in Kondratiev spaces to obtain solutions to the eikonal equation, and by extension to the nonlocal problem.
Neutrino oscillation: status and outlooks
International Nuclear Information System (INIS)
Nedelec, P.
1994-01-01
Whether the neutrinos are massive or not is one of the most puzzling question of physics today. If they are massive, they can contribute significantly to the Dark Matter of the Universe. An other consequence of a non-zero mass of neutrinos is that they might oscillate from one flavor to another. This oscillation process is by now the only way to detect a neutrino with a mass in the few eV range. Several neutrino experiments are currently looking for such an oscillation, in different modes, using different techniques. An overview of the experimental situation for neutrino experiments at accelerators is given. (author). 9 refs., 5 figs., 5 tabs
Collective oscillations in a plasma
Akhiezer, A I; Polovin, R V; ter Haar, D
2013-01-01
International Series of Monographs in Natural Philosophy: Collective Oscillations in a Plasma, Volume 7 presents specific topics within the general field of radio waves propagation. This book contains five chapters that address the theory of linear oscillations in a plasma, the spectra of the eigen oscillations, and the mechanism of high-frequency heating. The opening chapters deal with the self-consistent fields; development of initial perturbation; dispersion permittivity tensor of a plasma in a magnetic field; effect of thermal motion of particles on low-frequency resonances; excitation of
Coherent and squeezed states for the 3D harmonic oscillator
Mazouz, Amel; Bentaiba, Mustapha; Mahieddine, Ali
2017-01-01
A three-dimensional harmonic oscillator is studied in the context of generalized coherent states. We construct its squeezed states as eigenstates of linear contribution of ladder operators which are associated to the generalized Heisenberg algebra. We study the probability density to show the compression effect on the squeezed states. Our analysis reveals that squeezed states give us some freedom on the precise knowledge of position of the particle while maintaining the Heisenberg uncertainty relation minimum, squeezed states remains squeezed states over time.
Oscillations in Mathematical Biology
1983-01-01
The papers in this volume are based on talks given at a one day conference held on the campus of Adelphi University in April 1982. The conference was organized with the title "Oscillations in Mathematical Biology;" however the speakers were allowed considerable latitutde in their choice of topics. In the event, the talks all concerned the dynamics of non-linear systems arising in biology so that the conference achieved a good measure of cohesion. Some of the speakers cho~e not to submit a manuscript for these proceedings, feeling that their material was too conjectural to be committed to print. Also the paper of Rinzel and Troy is a distillation of the two separate talks that the authors gave. Otherwise the material reproduces the conference proceedings. The conference was made possible by the generous support of the Office of the Dean of the College of Arts and Sciences at Adelphi. The bulk of the organization of the conference was carried out by Dr. Ronald Grisell whose energy was in large measure responsib...
Principal oscillation patterns
International Nuclear Information System (INIS)
Storch, H. von; Buerger, G.; Storch, J.S. von
1993-01-01
The Principal Oscillation Pattern (POP) analysis is a technique which is used to simultaneously infer the characteristic patterns and time scales of a vector time series. The POPs may be seen as the normal modes of a linearized system whose system matrix is estimated from data. The concept of POP analysis is reviewed. Examples are used to illustrate the potential of the POP technique. The best defined POPs of tropospheric day-to-day variability coincide with the most unstable modes derived from linearized theory. POPs can be derived even from a space-time subset of data. POPs are successful in identifying two independent modes with similar time scales in the same data set. The POP method can also produce forecasts which may potentially be used as a reference for other forecast models. The conventional POP analysis technique has been generalized in various ways. In the cyclostationary POP analysis, the estimated system matrix is allowed to vary deterministically with an externally forced cycle. In the complex POP analysis not only the state of the system but also its ''momentum'' is modeled. Associated correlation patterns are a useful tool to describe the appearance of a signal previously identified by a POP analysis in other parameters. (orig.)
Rabi oscillation between states of a coupled harmonic oscillator
International Nuclear Information System (INIS)
Park, Tae Jun
2003-01-01
Rabi oscillation between bound states of a single potential is well known. However the corresponding formula between the states of two different potentials has not been obtained yet. In this work, we derive Rabi formula between the states of a coupled harmonic oscillator which may be used as a simple model for the electron transfer. The expression is similar to typical Rabi formula for a single potential. This result may be used to describe transitions between coupled diabatic potential curves
Directory of Open Access Journals (Sweden)
Manuel Jorge Hernández Rivero
2010-09-01
Full Text Available La úlcera varicosa es una de las complicaciones más temidas y frecuentes de la insuficiencia venosa crónica, por la sintomatología y discapacidad que provoca en el paciente y los elevados costos que ocasiona. Se presenta un caso de un paciente con antecedentes de de várices en miembros inferiores, y una úlcera varicosa de varios años de evolución en el miembro inferior izquierdo rebelde a diferentes tratamientos, a la cual se le realiza la técnica escleroterapia con espuma y se logra su cicatrización con una evolución favorable.The varicose ulcer is one of the more frequent and fearsome complications of chronic venous insufficiency due to its symptomatology and disability provoked in a patient with a history of lower extremities varices and the high related costs. This is the case a patient with a background of lower extremities varices and a varicose ulcer of some years of evolution in the left lower limb unmanageable for different treatments being necessary to perform the foam sclerotherapy technique achieving its healing with a favorable course.
Whiteley, Mark S; Holdstock, Judith M
2015-08-01
We present a woman with severe symptomatic recurrent varicose veins who was treated with endovenous laser ablation and transluminal occlusion of perforator with attempted phlebectomies for extensive varices. The phlebectomies turned out to be near impossible due to friability of the veins. Her treatment was completed with post-operative ultrasound guided foam sclerotherapy seven months later. She was subsequently diagnosed as Ehlers Danlos syndrome type IV. A duplex ultrasound scan 18 months post-endovenous laser ablation and transluminal occlusion of perforator and 11 months after ultrasound guided foam sclerotherapy confirmed successful closure with virtual atrophy of all treated veins. She was found to be reflux free and only showed a few scattered cosmetic reticular veins. Open varicose vein surgery has been reported as being hazardous in the past in a patient with Ehlers Danlos syndrome type IV. Our experience has shown that endovenous laser ablation, transluminal occlusion of perforator and ultrasound guided foam sclerotherapy appear to be effective in treating this patient with Ehlers Danlos syndrome type IV, although phlebectomies were technically impossible. © The Author(s) 2014.
Holdstock, J M; Dos Santos, S J; Harrison, C C; Price, B A; Whiteley, M S
2015-03-01
To determine the prevalence of haemorrhoids in women with pelvic vein reflux, identify which pelvic veins are associated with haemorrhoids and assess if extent of pelvic vein reflux influences the prevalence of haemorrhoids. Females presenting with leg varicose veins undergo duplex ultrasonography to assess all sources of venous reflux. Those with significant reflux arising from the pelvis are offered transvaginal duplex ultrasound (TVS) to evaluate reflux in the ovarian veins and internal Iliac veins and associated pelvic varices in the adnexa, vulvar/labial veins and haemorrhoids. Patterns and severity of reflux were evaluated. Between January 2010 and December 2012, 419 female patients with leg or vulvar varicose vein patterns arising from the pelvis underwent TVS. Haemorrhoids were identified on TVS via direct tributaries from the internal Iliac veins in 152/419 patients (36.3%) and absent in 267/419 (63.7%). The prevalence of the condition increased with the number of pelvic trunks involved. There is a strong association between haemorrhoids and internal Iliac vein reflux. Untreated reflux may be a cause of subsequent symptomatic haemorrhoids. Treatment with methods proven to work in conditions caused by pelvic vein incompetence, such as pelvic vein embolisation and foam sclerotherapy, could be considered. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Variations on a theme of q-oscillator
Pashaev, Oktay K.
2015-06-01
We present several ideas in the direction of physical interpretation of q- and f-oscillators as nonlinear oscillators. First we show that an arbitrary one-dimensional integrable system in action-angle variables can be naturally represented as a classical and quantum f-oscillator. As an example, the semi-relativistic oscillator as a descriptive of the Landau levels for relativistic electron in magnetic field is solved as an f-oscillator. By using dispersion relation for q-oscillator we solve the linear q-Schrödinger equation and corresponding nonlinear complex q-Burgers equation. The same dispersion allows us to construct integrable q-NLS model as a deformation of cubic NLS in terms of recursion operator of NLS hierarchy. A peculiar property of the model is to be completely integrable at any order of expansion in deformation parameter around q = 1. As another variation on the theme, we consider hydrodynamic flow in bounded domain. For the flow bounded by two concentric circles we formulate the two circle theorem and construct the solution as the q-periodic flow by non-symmetric q-calculus. Then we generalize this theorem to the flow in the wedge domain bounded by two arcs. This two circular-wedge theorem determines images of the flow by extension of q-calculus to two bases: the real one, corresponding to circular arcs and the complex one, with q as a primitive root of unity. As an application, the vortex motion in annular domain as a nonlinear oscillator in the form of classical and quantum f-oscillator is studied. Extending idea of q-oscillator to two bases with the golden ratio, we describe Fibonacci numbers as a special type of q-numbers with matrix Binet formula. We derive the corresponding golden quantum oscillator, nonlinear coherent states and Fock-Bargman representation. Its spectrum satisfies the triple relations, while the energy levels’ relative difference approaches asymptotically to the golden ratio and has no classical limit.
Global Status of Neutrino Oscillation
Indian Academy of Sciences (India)
monojit
2014-11-08
Outline of talk. Neutrino Oscillations: the context. Solar and geo neutrino physics. Reactor neutrino physics. Atmospheric and long-baseline neutrino physics. Atmospheric neutrinos and INO. Nov 8, 2014, IASc Annual Meeting, IIT-Madras, Chennai – p. 2 ...
Strongly nonlinear oscillators analytical solutions
Cveticanin, Livija
2014-01-01
This book provides the presentation of the motion of pure nonlinear oscillatory systems and various solution procedures which give the approximate solutions of the strong nonlinear oscillator equations. The book presents the original author’s method for the analytical solution procedure of the pure nonlinear oscillator system. After an introduction, the physical explanation of the pure nonlinearity and of the pure nonlinear oscillator is given. The analytical solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter is considered. Special attention is given to the one and two mass oscillatory systems with two-degrees-of-freedom. The criteria for the deterministic chaos in ideal and non-ideal pure nonlinear oscillators are derived analytically. The method for suppressing chaos is developed. Important problems are discussed in didactic exercises. The book is self-consistent and suitable as a textbook for students and also for profess...
Modelling solar-like oscillators
Energy Technology Data Exchange (ETDEWEB)
Eggenberger, P; Miglio, A [Institut d' Astrophysique et de Geophysique de l' Universite de Liege, 17 Allee du 6 Aout, B-4000 Liege (Belgium); Carrier, F [Institute of Astronomy, University of Leuven, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Mathis, S [CEA/DSM/DAPNIA/Service d' Astrophysique, CEA/Saclay, AIM-Unite Mixte de Recherche CEA-CNRS-Universite Paris VII, UMR 7158, 91191 Gif-sur-Yvette Cedex (France)], E-mail: eggenberger@Qastro.ulg.ac.be
2008-10-15
The computation of models of stars for which solar-like oscillations have been observed is discussed. After a brief intoduction on the observations of solar-like oscillations, the modelling of isolated stars and of stars belonging to a binary system is presented with specific examples of recent theoretical calibrations. Finally the input physics introduced in stellar evolution codes for the computation of solar-type stars is discussed with a peculiar emphasis on the modelling of rotation for these stars.
Control electron beam oscillation regimes in Pierce diode with overcritical current
International Nuclear Information System (INIS)
Rempen, I.S.; Khramov, A.E.
2001-01-01
The effect of the delayed feedback on the complex oscillation regimes in the electron flux with the overcritical current in the Pierce diode is studied. The possibility of controlling the oscillation regimes through changing the feedback parameters is shown. The finite-dimensional model, describing the behavior of the electron flux in the Pierce diode hydrodynamic model, is constructed. Its behavior under the effect of the delayed feedback is studied [ru
Periodic window arising in the parameter space of an impact oscillator
International Nuclear Information System (INIS)
Medeiros, E.S.; Souza, S.L.T. de; Medrano-T, R.O.; Caldas, I.L.
2010-01-01
In the bi-dimensional parameter space of an impact-pair system, shrimp-shaped periodic windows are embedded in chaotic regions. We show that a weak periodic forcing generates new periodic windows near the unperturbed one with its shape and periodicity. Thus, the new periodic windows are parameter range extensions for which the controlled periodic oscillations substitute the chaotic oscillations. We identify periodic and chaotic attractors by their largest Lyapunov exponents.
Modeling nonlinearities in MEMS oscillators.
Agrawal, Deepak K; Woodhouse, Jim; Seshia, Ashwin A
2013-08-01
We present a mathematical model of a microelectromechanical system (MEMS) oscillator that integrates the nonlinearities of the MEMS resonator and the oscillator circuitry in a single numerical modeling environment. This is achieved by transforming the conventional nonlinear mechanical model into the electrical domain while simultaneously considering the prominent nonlinearities of the resonator. The proposed nonlinear electrical model is validated by comparing the simulated amplitude-frequency response with measurements on an open-loop electrically addressed flexural silicon MEMS resonator driven to large motional amplitudes. Next, the essential nonlinearities in the oscillator circuit are investigated and a mathematical model of a MEMS oscillator is proposed that integrates the nonlinearities of the resonator. The concept is illustrated for MEMS transimpedance-amplifier- based square-wave and sine-wave oscillators. Closed-form expressions of steady-state output power and output frequency are derived for both oscillator models and compared with experimental and simulation results, with a good match in the predicted trends in all three cases.
Hsieh, T.; Coakley, T. J.
1987-01-01
An investigation of downstream boundary effects on the frequency of self-excited oscillations in two-dimensional, separated transonic diffuser flows has been conducted numerically by solving the compressible, Reynolds-averaged, thin-layer Navier-Stokes equation with a two-equation turbulence model. It was found that the unsteady diffuser flowfields are very sensitive to the location of the downstream boundary. Extension of the diffuser downstream boundary significantly reduces the frequency and amplitude of oscillations for pressure, velocity and shock. Computational results suggest that the mechanism causing the self-excited oscillation changes from viscous convective wave dominated oscillations to inviscid acoustic wave dominated oscillations when the location of downstream boundary varies from 8.66 to 134.7 throat height. The existence of a suction slot in the experimental setup obscures the physical downstream boundary and, therefore, presents a difficulty for quantitative comparisons between computation and experiment.
Magnetically Coupled Magnet-Spring Oscillators
Donoso, G.; Ladera, C. L.; Martin, P.
2010-01-01
A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of…
On the nonlinear modeling of ring oscillators
Elwakil, Ahmed S.
2009-06-01
We develop higher-order nonlinear models of three-stage and five-stage ring oscillators based on a novel inverter model. The oscillation condition and oscillation frequency are derived and compared to classical linear model analysis. Two important special cases for five-stage ring oscillators are also studied. Numerical simulations are shown. © 2009 World Scientific Publishing Company.
Density wave oscillations of a boiling natural circulation loop induced by flashing
Energy Technology Data Exchange (ETDEWEB)
Furuya, Masahiro; Inada, Fumio; Yasuo, Akira [Central Research Institute of Electric Power Industry, Tokyo (Japan)
1995-09-01
Experiments are conducted to investigate two-phase flow instabilities in a boiling natural circulation loop with a chimney due to flashing in the chimney at lower pressure. The test facility used in this experiment is designed to have non-dimensional values which are nearly equal to those of natural circulation BWR. Stability maps in reference to the heat flux, the inlet subcooling, the system pressure are presented. This instability is suggested to be density wave oscillations due to flashing in the chimney, and the differences from other phenomena such as flow pattern oscillations and geysering phenomena are discussed by investigating the dynamic characteristics, the oscillation period, and the transient flow pattern.
The quantum harmonic oscillator on a circle and a deformed quantum field theory
International Nuclear Information System (INIS)
Rego-Monteiro, M.A.
2001-05-01
We construct a deformed free quantum field theory with an standard Hilbert space based on a deformed Heisenberg algebra. This deformed algebra is a Heisenberg-type algebra describing the first levels of the quantum harmonic oscillator on a circle of large length L. The successive energy levels of this quantum harmonic oscillator on a circle of large length L are interpreted, similarly to the standard quantum one-dimensional harmonic oscillator on an infinite line, as being obtained by the creation of a quantum particle of frequency w at very high energies. (author)
Hyperbolic chaos in the klystron-type microwave vacuum tube oscillator.
Emel'yanov, V V; Kuznetsov, S P; Ryskin, N M
2010-12-01
The ring-loop oscillator consisting of two coupled klystrons which is capable of generating hyperbolic chaotic signal in the microwave band is considered. The system of delayed-differential equations describing the dynamics of the oscillator is derived. This system is further reduced to the two-dimensional return map under the assumption of the instantaneous build-up of oscillations in the cavities. The results of detailed numerical simulation for both models are presented showing that there exists large enough range of control parameters where the sustained regime corresponds to the structurally stable hyperbolic chaos. © 2010 American Institute of Physics.
Numerical simulation of self-excited oscillations in a ramjet inlet-diffuser flow
Hsieh, T.; Coakley, T.
1985-01-01
This paper describes numerical simulations of self-excited oscillations in a two-dimensional transonic inlet-diffuser flow by solving the Navier-Stokes equations with a two-equation turbulence model. The calculated amplitudes of oscillations for the terminal shock and the velocity fields compare well with experimental measurements; however, the predicted frequency of oscillations is about 50 percent higher. The formation of a pair of downstream-traveling, counter-rotating vortices at each cycle of velocity fluctuations, as reported experimentally, is vividly revealed by the numerical results.
On the mechanism of oscillations in neutrophils
DEFF Research Database (Denmark)
Brasen, Jens Christian; Barington, Torben; Olsen, Lars Folke
2010-01-01
We have investigated the regulation of the oscillatory generation of H(2)O(2) and oscillations in shape and size in neutrophils in suspension. The oscillations are independent of cell density and hence do not represent a collective phenomena. Furthermore, the oscillations are independent...... of the external glucose concentration and the oscillations in H(2)O(2) production are 180 degrees out of phase with the oscillations in NAD(P)H. Cytochalasin B blocked the oscillations in shape and size whereas it increased the period of the oscillations in H(2)O(2) production. 1- and 2-butanol also blocked...... the oscillations in shape and size, but only 1-butanol inhibited the oscillations in H(2)O(2) production. We conjecture that the oscillations are likely to be due to feedback regulations in the signal transduction cascade involving phosphoinositide 3-kinases (PI3K). We have tested this using a simple mathematical...
Beard, George F; Griffin, Michael J
2013-01-01
Roll compensation during cornering (aligning the feet-to-head axis of the body with the resultant force) reduces lateral acceleration, but how any improvement in comfort depends on the frequency of the acceleration has not previously been investigated. Seated subjects judged the discomfort caused by lateral oscillation, roll oscillation and fully roll-compensated lateral oscillation at each of seven frequencies (0.25-1.0 Hz). Irrespective of whether it was caused by pure lateral acceleration or gravitational acceleration due to pure roll, acceleration in the plane of the seat caused similar discomfort at frequencies less than 0.4 Hz. From 0.4 to 1.0 Hz, with the same lateral acceleration in the plane of the seat, there was greater discomfort from roll oscillation than from lateral acceleration. With fully roll-compensated lateral oscillation, discomfort was less than with either the lateral component or the roll component of the motion from 0.2 to 0.5 Hz, but discomfort increased with increasing frequency and caused similar discomfort to pure roll oscillation at 1.0 Hz. Tilting can reduce passenger exposure to vehicle lateral acceleration when cornering, but how comfort depends on the frequency of motion was unknown. This study shows 'tilt-compensation' only improves comfort at frequencies less than 0.5 Hz. The findings affect tilting vehicles and the prediction of discomfort caused by low-frequency motions.
Directory of Open Access Journals (Sweden)
Ikuhiro Yamaguchi
Full Text Available Time delay is known to induce sustained oscillations in many biological systems such as electroencephalogram (EEG activities and gene regulations. Furthermore, interactions among delay-induced oscillations can generate complex collective rhythms, which play important functional roles. However, due to their intrinsic infinite dimensionality, theoretical analysis of interacting delay-induced oscillations has been limited. Here, we show that the two primary methods for finite-dimensional limit cycles, namely, the center manifold reduction in the vicinity of the Hopf bifurcation and the phase reduction for weak interactions, can successfully be applied to interacting infinite-dimensional delay-induced oscillations. We systematically derive the complex Ginzburg-Landau equation and the phase equation without delay for general interaction networks. Based on the reduced low-dimensional equations, we demonstrate that diffusive (linearly attractive coupling between a pair of delay-induced oscillations can exhibit nontrivial amplitude death and multimodal phase locking. Our analysis provides unique insights into experimentally observed EEG activities such as sudden transitions among different phase-locked states and occurrence of epileptic seizures.
ALG-2 oscillates in subcellular localization, unitemporally with calcium oscillations
DEFF Research Database (Denmark)
la Cour, Jonas Marstrand; Mollerup, Jens; Berchtold, Martin Werner
2007-01-01
A variety of stimuli can trigger intracellular calcium oscillations. Relatively little is known about the molecular mechanisms decoding these events. We show that ALG-2, a Ca2+-binding protein originally isolated as a protein associated with apoptosis, is directly linked to Ca2+ signalling. We...... localization in an oscillatory fashion unitemporally with Ca2+ oscillations, whereas a Ca2+-binding deficient mutant of ALG-2 did not redistribute. Using tagged ALG-2 as bait we identified its novel target protein Sec31A and based on the partial colocalization of endogenous ALG-2 and Sec31A we propose that ALG...
Nonlinear dimensionality reduction in climate data
Directory of Open Access Journals (Sweden)
A. J. Gámez
2004-01-01
Full Text Available Linear methods of dimensionality reduction are useful tools for handling and interpreting high dimensional data. However, the cumulative variance explained by each of the subspaces in which the data space is decomposed may show a slow convergence that makes the selection of a proper minimum number of subspaces for successfully representing the variability of the process ambiguous. The use of nonlinear methods can improve the embedding of multivariate data into lower dimensional manifolds. In this article, a nonlinear method for dimensionality reduction, Isomap, is applied to the sea surface temperature and thermocline data in the tropical Pacific Ocean, where the El Niño-Southern Oscillation (ENSO phenomenon and the annual cycle phenomena interact. Isomap gives a more accurate description of the manifold dimensionality of the physical system. The knowledge of the minimum number of dimensions is expected to improve the development of low dimensional models for understanding and predicting ENSO.
Nonlinear dimensionality reduction in climate data
Gámez, A. J.; Zhou, C. S.; Timmermann, A.; Kurths, J.
2004-09-01
Linear methods of dimensionality reduction are useful tools for handling and interpreting high dimensional data. However, the cumulative variance explained by each of the subspaces in which the data space is decomposed may show a slow convergence that makes the selection of a proper minimum number of subspaces for successfully representing the variability of the process ambiguous. The use of nonlinear methods can improve the embedding of multivariate data into lower dimensional manifolds. In this article, a nonlinear method for dimensionality reduction, Isomap, is applied to the sea surface temperature and thermocline data in the tropical Pacific Ocean, where the El Niño-Southern Oscillation (ENSO) phenomenon and the annual cycle phenomena interact. Isomap gives a more accurate description of the manifold dimensionality of the physical system. The knowledge of the minimum number of dimensions is expected to improve the development of low dimensional models for understanding and predicting ENSO.
Li, B.; Alimi, Y.; Ma, G. L.
2016-12-01
Current oscillations in an AlGaAs/InGaAs/AlGaAs-based two-dimensional electron gas (2DEG)-based hetero-structure have been investigated by means of semiconductor device simulation software SILVACO, with an interest on the charge domain formation at large biases. Single-frequency oscillations are generated in planar Gunn diodes with uniform anode and cathode contacts. The oscillation frequency reduces as the applied bias voltage increases. We show that it is possible to create multiple, independent charge domains in a novel Gunn diode structure with designed multiple anode-cathode spacings. This enables simultaneous generation of multiple frequency oscillations in a single planar device, in contrast to traditional vertical Gunn diodes where only single-frequency oscillations can be achieved. More interestingly, frequency mixing in multiple-channel configured Gunn diodes appeared. This proof-of-concept opens up the possibility for realizing compact self-oscillating mixer at millimeter-wave applications.
Real oscillations of virtual neutrinos
International Nuclear Information System (INIS)
Grimus, W.; Stockinger, P.
1996-01-01
We study the conditions for neutrino oscillations in a field-theoretical approach by taking into account that only the neutrino production and detection processes, which are localized in space around the coordinates x searrow P and x searrow D , respectively, can be manipulated. In this sense the neutrinos whose oscillations are investigated appear as virtual lines connecting production with detection in the total Feynman graph and all neutrino fields or states to be found in the discussion are mass eigenfields or eigenstates. We perform a thorough examination of the integral over the spatial components of the inner neutrino momentum and show that in the asymptotic limit L=|x searrow D -x searrow P |→∞ the virtual neutrinos become open-quote open-quote real close-quote close-quote and under certain conditions the usual picture of neutrino oscillations emerges without ambiguities. copyright 1996 The American Physical Society
Damping of coupled harmonic oscillators
Dolfo, Gilles; Vigué, Jacques
2018-03-01
When two harmonic oscillators are coupled in the presence of damping, their dynamics exhibit two very different regimes depending on the relative magnitude of the coupling and damping terms At resonance, when the coupling has its largest effect, if the coupling dominates the damping, there is a periodic exchange of energy between the two oscillators while, in the opposite case, the energy transfer from one oscillator to the other one is irreversible. We prove that the border between these two regimes goes through an exceptional point and we briefly explain what is an exceptional point. The present paper is written for undergraduate students, with some knowledge in classical mechanics, but it may also be of interest for graduate students.
Prediction of pilot induced oscillations
Directory of Open Access Journals (Sweden)
Valentin PANĂ
2011-03-01
Full Text Available An important problem in the design of flight-control systems for aircraft under pilotedcontrol is the determination of handling qualities and pilot-induced oscillations (PIO tendencieswhen significant nonlinearities exist in the vehicle description. The paper presents a method to detectpossible pilot-induced oscillations of Category II (with rate and position limiting, a phenomenonusually due to a misadaptation between the pilot and the aircraft response during some tasks in whichtight closed loop control of the aircraft is required from the pilot. For the analysis of Pilot in the LoopOscillations an approach, based on robust stability analysis of a system subject to uncertainparameters, is proposed. In this analysis the nonlinear elements are substituted by linear uncertainparameters. This approach assumes that PIO are characterized by a limit cycle behavior.
DIGITAL SELF-OSCILLATING MODULATOR
DEFF Research Database (Denmark)
2007-01-01
A digital self-oscillating modulator (1) having a digital reference signal as input (Vref) comprises a forward loop with a first output and a feedback loop. The feedback loop comprises a feedback block (18) having a transfer function (MFB) and a digital output. The forward loop comprises an alter......A digital self-oscillating modulator (1) having a digital reference signal as input (Vref) comprises a forward loop with a first output and a feedback loop. The feedback loop comprises a feedback block (18) having a transfer function (MFB) and a digital output. The forward loop comprises...
Spontaneous oscillations in microfluidic networks
Case, Daniel; Angilella, Jean-Regis; Motter, Adilson
2017-11-01
Precisely controlling flows within microfluidic systems is often difficult which typically results in systems being heavily reliant on numerous external pumps and computers. Here, I present a simple microfluidic network that exhibits flow rate switching, bistablity, and spontaneous oscillations controlled by a single pressure. That is, by solely changing the driving pressure, it is possible to switch between an oscillating and steady flow state. Such functionality does not rely on external hardware and may even serve as an on-chip memory or timing mechanism. I use an analytic model and rigorous fluid dynamics simulations to show these results.
TOWARDS THRESHOLD FREQUENCY IN CHAOTIC COLPITTS OSCILLATOR
DEFF Research Database (Denmark)
Lindberg, Erik; Tamasevicius, Arunas; Mykolaitis, Gytis
2007-01-01
A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations at the funda......A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations...
[Esthetic treatment of varicosities].
Vin, F
2000-06-01
Telangiectasia is dilatation of the subpapillary venous plexus of the epidermis of the lower limbs, which can lead to aesthetic embarrassment. Before treating telangiectasia, patient history and clinical examination help establishing its origin. It can be with isolated, associated reticular drainage veins, or be part of superficial venous insufficiency. Several types of treatment have been proposed. Microsclerotherapy is the most effective and least costly. Muller's phlebectomy can be performed when telangiectasia is fed by large reticular veins, either afferent or efferent. Treatment by laser and pulsed light appear best reserved to treatment of finer venous dilatations, either complementary or after failure of sclerotherapy.
Simulations of fully deformed oscillating flux tubes
Karampelas, K.; Van Doorsselaere, T.
2018-02-01
Context. In recent years, a number of numerical studies have been focusing on the significance of the Kelvin-Helmholtz instability in the dynamics of oscillating coronal loops. This process enhances the transfer of energy into smaller scales, and has been connected with heating of coronal loops, when dissipation mechanisms, such as resistivity, are considered. However, the turbulent layer is expected near the outer regions of the loops. Therefore, the effects of wave heating are expected to be confined to the loop's external layers, leaving their denser inner parts without a heating mechanism. Aim. In the current work we aim to study the spatial evolution of wave heating effects from a footpoint driven standing kink wave in a coronal loop. Methods: Using the MPI-AMRVAC code, we performed ideal, three dimensional magnetohydrodynamic simulations of footpoint driven transverse oscillations of a cold, straight coronal flux tube, embedded in a hotter environment. We have also constructed forward models for our simulation using the FoMo code. Results: The developed transverse wave induced Kelvin-Helmholtz (TWIKH) rolls expand throughout the tube cross-section, and cover it entirely. This turbulence significantly alters the initial density profile, leading to a fully deformed cross section. As a consequence, the resistive and viscous heating rate both increase over the entire loop cross section. The resistive heating rate takes its maximum values near the footpoints, while the viscous heating rate at the apex. Conclusions: We conclude that even a monoperiodic driver can spread wave heating over the whole loop cross section, potentially providing a heating source in the inner loop region. Despite the loop's fully deformed structure, forward modelling still shows the structure appearing as a loop. A movie attached to Fig. 1 is available at http://https://www.aanda.org
Ellipsoidal basis for isotropic oscillator
International Nuclear Information System (INIS)
Kallies, W.; Lukac, I.; Pogosyan, G.S.; Sisakyan, A.N.
1994-01-01
The solutions of the Schroedinger equation are derived for the isotropic oscillator potential in the ellipsoidal coordinate system. The explicit expression is obtained for the ellipsoidal integrals of motion through the components of the orbital moment and Demkov's tensor. The explicit form of the ellipsoidal basis is given for the lowest quantum numbers. 10 refs.; 1 tab. (author)
Oscillating solitons in nonlinear optics
Indian Academy of Sciences (India)
Abstract. Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable- coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota's bilinear method. The bilinear forms and analytic soliton solutions are derived, and the ...
Low-Vibration Oscillating Compressor
Studer, P. A.
1984-01-01
Oscillating compressor momentum compensated: produces little vibration in its supporting structure. Compressure requires no lubrication and virtually free of wear. Compresses working fluids such as helium, nitrogen or chlorfluorocarbons for Stirling-cycle refrigeration or other purposes. Compressor includes two mutually opposed ferromagnetic pistons of same shape and mass. Electromagnetic flux links both pistons, causing magnetic attraction between them.
Sound oscillation of dropwise cluster
Energy Technology Data Exchange (ETDEWEB)
Shavlov, A.V., E-mail: shavlov@ikz.ru [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation); Dzhumandzhi, V.A.; Romanyuk, S.N. [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation)
2012-06-04
There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10{sup 2}–10{sup 3} units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.
Sound oscillation of dropwise cluster
International Nuclear Information System (INIS)
Shavlov, A.V.; Dzhumandzhi, V.A.; Romanyuk, S.N.
2012-01-01
There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10 2 –10 3 units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.
Numerical simulation of electron beam welding with beam oscillations
Trushnikov, D. N.; Permyakov, G. L.
2017-02-01
This research examines the process of electron-beam welding in a keyhole mode with the use of beam oscillations. We study the impact of various beam oscillations and their parameters on the shape of the keyhole, the flow of heat and mass transfer processes and weld parameters to develop methodological recommendations. A numerical three-dimensional mathematical model of electron beam welding is presented. The model was developed on the basis of a heat conduction equation and a Navier-Stokes equation taking into account phase transitions at the interface of a solid and liquid phase and thermocapillary convection (Marangoni effect). The shape of the keyhole is determined based on experimental data on the parameters of the secondary signal by using the method of a synchronous accumulation. Calculations of thermal and hydrodynamic processes were carried out based on a computer cluster, using a simulation package COMSOL Multiphysics.
Gate-tunable graphene quantum dot and Dirac oscillator
Belouad, Abdelhadi; Jellal, Ahmed; Zahidi, Youness
2016-02-01
We obtain the solution of the Dirac equation in (2 + 1) dimensions in the presence of a constant magnetic field normal to the plane together with a two-dimensional Dirac-oscillator potential coupling. We study the energy spectrum of graphene quantum dot (QD) defined by electrostatic gates. We give discussions of our results based on different physical settings, whether the cyclotron frequency is similar or larger/smaller compared to the oscillator frequency. This defines an effective magnetic field that produces the effective quantized Landau levels. We study analytically such field in gate-tunable graphene QD and show that our structure allows us to control the valley degeneracy. Finally, we compare our results with already published work and also discuss the possible applications of such QD.
Asynchronous oscillations of rigid rods drive viscous fluid to swirl
Hayashi, Rintaro; Takagi, Daisuke
2017-12-01
We present a minimal system for generating flow at low Reynolds number by oscillating a pair of rigid rods in silicone oil. Experiments show that oscillating them in phase produces no net flow, but a phase difference alone can generate rich flow fields. Tracer particles follow complex trajectory patterns consisting of small orbital movements every cycle and then drifting or swirling in larger regions after many cycles. Observations are consistent with simulations performed using the method of regularized Stokeslets, which reveal complex three-dimensional flow structures emerging from simple oscillatory actuation. Our findings reveal the basic underlying flow structure around oscillatory protrusions such as hairs and legs as commonly featured on living and nonliving bodies.
Mobility induces global synchronization of oscillators in periodic extended systems
International Nuclear Information System (INIS)
Peruani, Fernando; Nicola, Ernesto M; Morelli, Luis G
2010-01-01
We study the synchronization of locally coupled noisy phase oscillators that move diffusively in a one-dimensional ring. Together with the disordered and the globally synchronized states, the system also exhibits wave-like states displaying local order. We use a statistical description valid for a large number of oscillators to show that for any finite system there is a critical mobility above which all wave-like solutions become unstable. Through Langevin simulations, we show that the transition to global synchronization is mediated by a shift in the relative size of attractor basins associated with wave-like states. Mobility disrupts these states and paves the way for the system to attain global synchronization.
Pseudochaotic kicked oscillators renormalization, symbolic dynamics, and transport
Lowenstein, John H
2012-01-01
"Pseudochaotic Kicked Oscillators: Renormalization, Symbolic Dynamics, and Transport" presents recent developments in pseudochaos, which is concerned with complex branching behaviors of dynamical systems at the interface between orderly and chaotic motion. Pseudochaos is characterized by the trapping of orbits in the vicinity of self-similar hierarchies of islands of stability, producing phase-space displacements which increase asymptotically as a power of time. This monograph is a thorough, self-contained investigation of a simple one-dimensional model (a kicked harmonic oscillator) which exhibits pseudochaos in its purest form. It is intended for graduate students and researchers in physics and applied mathematics, as well as specialists in nonlinear dynamics. Dr. John H. Lowenstein is a Professor Emeritus in the Department of Physics at New York University, USA.
Baryon acoustic oscillation intensity mapping of dark energy.
Chang, Tzu-Ching; Pen, Ue-Li; Peterson, Jeffrey B; McDonald, Patrick
2008-03-07
The expansion of the Universe appears to be accelerating, and the mysterious antigravity agent of this acceleration has been called "dark energy." To measure the dynamics of dark energy, baryon acoustic oscillations (BAO) can be used. Previous discussions of the BAO dark energy test have focused on direct measurements of redshifts of as many as 10(9) individual galaxies, by observing the 21 cm line or by detecting optical emission. Here we show how the study of acoustic oscillation in the 21 cm brightness can be accomplished by economical three-dimensional intensity mapping. If our estimates gain acceptance they may be the starting point for a new class of dark energy experiments dedicated to large angular scale mapping of the radio sky, shedding light on dark energy.
Dirac bound states of anharmonic oscillator in external fields
Energy Technology Data Exchange (ETDEWEB)
Hamzavi, Majid, E-mail: majid.hamzavi@gmail.com [Department of Physics, University of Zanjan, Zanjan (Iran, Islamic Republic of); Ikhdair, Sameer M., E-mail: sikhdair@gmail.com [Department of Physics, Faculty of Science, an-Najah National University, Nablus, West Bank, Palestine (Country Unknown); Department of Electrical and Electronic Engineering, Near East University, 922022 Nicosia, Northern Cyprus, Mersin 10 (Turkey); Falaye, Babatunde J., E-mail: fbjames11@physicist.net [Theoretical Physics Section, Department of Physics, University of Ilorin, P. M. B. 1515, Ilorin (Nigeria)
2014-02-15
We explore the effect of the external magnetic and Aharonov–Bohm (AB) flux fields on the energy levels of Dirac particle subjects to mixed scalar and vector anharmonic oscillator field in the two-dimensional (2D) space. We calculate the exact energy eigenvalues and the corresponding un-normalized two-spinor-components wave functions in terms of the chemical potential parameter, magnetic field strength, AB flux field and magnetic quantum number by using the Nikiforov–Uvarov (NU) method. -- Highlights: • Effect of the external fields on the energy levels of Dirac particle with the anharmonic oscillator is investigated. • The solutions are discussed in view of spin and pseudospin symmetries limits. • The energy levels and wave function are presented by the Nikiforov–Uvarov method.
Dirac bound states of anharmonic oscillator in external fields
International Nuclear Information System (INIS)
Hamzavi, Majid; Ikhdair, Sameer M.; Falaye, Babatunde J.
2014-01-01
We explore the effect of the external magnetic and Aharonov–Bohm (AB) flux fields on the energy levels of Dirac particle subjects to mixed scalar and vector anharmonic oscillator field in the two-dimensional (2D) space. We calculate the exact energy eigenvalues and the corresponding un-normalized two-spinor-components wave functions in terms of the chemical potential parameter, magnetic field strength, AB flux field and magnetic quantum number by using the Nikiforov–Uvarov (NU) method. -- Highlights: • Effect of the external fields on the energy levels of Dirac particle with the anharmonic oscillator is investigated. • The solutions are discussed in view of spin and pseudospin symmetries limits. • The energy levels and wave function are presented by the Nikiforov–Uvarov method
Tan, Qingming
2011-01-01
Dimensional analysis is an essential scientific method and a powerful tool for solving problems in physics and engineering. This book starts by introducing the Pi Theorem, which is the theoretical foundation of dimensional analysis. It also provides ample and detailed examples of how dimensional analysis is applied to solving problems in various branches of mechanics. The book covers the extensive findings on explosion mechanics and impact dynamics contributed by the author's research group over the past forty years at the Chinese Academy of Sciences. The book is intended for advanced undergra
Characterizing brain oscillations in cognition and disease
Jiang, H.
2016-01-01
It has been suggested that neuronal oscillations play a fundamental role for shaping the functional architecture of the working brain. This thesis investigates brain oscillations in rat, human healthy population and major depressive disorder (MDD) patients. A novel measurement termed
Cyanohydrin reactions enhance glycolytic oscillations in yeast
DEFF Research Database (Denmark)
Hald, Bjørn Olav; Nielsen, Astrid Gram; Tortzen, Christian
2015-01-01
Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here...
Analytic Neutrino Oscillation Probabilities in Matter: Revisited
Energy Technology Data Exchange (ETDEWEB)
Parke, Stephen J. [Fermilab; Denton, Peter B. [Copenhagen U.; Minakata, Hisakazu [Madrid, IFT
2018-01-02
We summarize our recent paper on neutrino oscillation probabilities in matter, explaining the importance, relevance and need for simple, highly accurate approximations to the neutrino oscillation probabilities in matter.
Internal dynamics of long Josephson junction oscillators
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.
1981-01-01
Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numeric...... results imply a ''bunched-fluxon'' mode of oscillation at larger values of bias current. Applied Physics Letters is copyrighted by The American Institute of Physics....
Nonlinear analysis of ring oscillator circuits
Ge, Xiaoqing
2010-06-01
Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.
A theory of generalized Bloch oscillations
DEFF Research Database (Denmark)
Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny
2016-01-01
Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact...... oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics....
Effective harmonic oscillator description of anharmonic molecular ...
Indian Academy of Sciences (India)
Administrator
The effective harmonic oscillator is constructed variationally, by taking the trial wave function as a harmonic oscillator eigenfunction with the centroid and width parameter as variational para- eters. It is found that the effective harmonic oscillator approximation provides a description of the anharmonic eigenstates very similar ...
Assessing the quality of stochastic oscillations
Indian Academy of Sciences (India)
Population dynamics; stochastic oscillations. ... We propose a quantification of the oscillatory appearance of the fluctuating populations, and show that good stochastic oscillations are present if a parameter of the macroscopic model is small, and that no microscopic model will show oscillations if that parameter is large.
Neutrino oscillations in the early universe
International Nuclear Information System (INIS)
Enqvist, K.
1990-01-01
The oscillations of electron neutrinos into inert neutrinos may have resonant behaviour in the heat bath of the early Universe. It is shown that any initial neutrino asymmetry will be washed away by the oscillations. Neutrino oscillations would affect also primordial helium production, which implies stringent limits on the neutrino mixing parameters. (orig.)
Dependence of synchronization frequency of Kuramoto oscillators ...
Indian Academy of Sciences (India)
journal of. December 2014 physics pp. 945–953. Dependence of synchronization frequency of Kuramoto oscillators on symmetry of intrinsic frequency in ring ... In this article, we study the difference between networks with sym- ... The dynamics of a general ith oscillator in a system of N Kuramoto oscillators is given as.
Three flavour oscillation interpretation of neutrino data
Indian Academy of Sciences (India)
To explain the atmospheric neutrino problem in terms of neutrino oscillations, ЖС¾ of about 10-¿. eV. ¾. [8] is needed whereas the neutrino oscil- lation solution to the solar neutrino problem requires ЖС¾ ~10- eV. ¾ . Hence both solar and atmospheric neutrino problems cannot be explained in terms of e ° μ oscillations.
Comparison of Methods for Oscillation Detection
DEFF Research Database (Denmark)
Odgaard, Peter Fogh; Trangbæk, Klaus
2006-01-01
This paper compares a selection of methods for detecting oscillations in control loops. The methods are tested on measurement data from a coal-fired power plant, where some oscillations are occurring. Emphasis is put on being able to detect oscillations without having a system model and without u...
Canards and mixed-mode oscillations in a forest pest model
DEFF Research Database (Denmark)
Brøns, Morten; Kaasen, Rune
2010-01-01
of high pest concentration. For small values of the timescale of the young trees, the model can be reduced to a two-dimensional model. By a geometrical analysis we identify a canard explosion in the reduced model, that is, a change over a narrow parameter interval from outbreak dynamics to small......We consider a three-variable forest pest model, proposed by Rinaldi & Muratori (1992) [Rinaldi, S., Muratori, S., 1992. Limit cycles in slow-fast forest-pest models. Theor. Popul. Biol. 41,26-43]. The model allows relaxation oscillations where long pest-free periods are interspersed with outbreaks...... oscillations around an endemic state. For larger values of the timescale of the young trees the two-dimensional approximation breaks down, and a broader parameter interval with mixed-mode oscillations appear, replacing the simple canard explosion. The analysis only relies on simple and generic properties...
On the non-linear dynamics of potential relaxation oscillations in bounded plasmas
International Nuclear Information System (INIS)
Krssak, M.; Skalny, J.D.; Gyergyek, T.; Cercek, M.
2007-01-01
Plasma in a 1-dimensional diode is studied theoretically and the computer simulations are used for verification of the theoretical model. When collector in the diode is biased positively, a double-layer is created in the system and consequently, we are able to observe oscillations of the potential, density and other plasma parameters. When external periodic forcing is applied, spectra of these oscillations are changed and effects of synchronisation and periodic pulling can be observed. Both of these effects are of non-linear nature and a good explanation is found using the analogy with Van der Pol oscillators. Following [1] and [2] approximate analytical solutions are found and then compared with computer simulations obtained using a 1-dimensional particle-in-cell code XPDP1. (author)
Modelling of low-current self-generated oscillations in a hollow cathode discharge
Donko, Z
1999-01-01
Low-current self-generated oscillations in a rectangular hollow cathode discharge in helium gas were investigated experimentally and by means of a two-dimensional self-consistent hybrid model. The model combines Monte Carlo simulation of the motion of fast electrons and a fluid description of slow electrons and positive ions. The low-frequency (<=20 kHz) oscillations were found to arise as an effect of the interaction of the gas discharge and the external electric circuit - consisting of a stable voltage source, a series resistor and a capacitor formed by the discharge electrodes. Good agreement was found between the experimentally observed and calculated oscillation frequency and current wave forms. Beside these characteristics the modelling also made it possible to calculate the time dependence of numerous other discharge characteristics (e.g. electron multiplication, ion density, potential distribution) and provided detailed insight into the mechanism of oscillations. The advantage of the present model ...
Kogan, Oleg; Refael, Gil; Cross, Michael; Rogers, Jeffrey
2008-03-01
We develop a renormalization group (RG) method to predict frequency clusters and their statistical properties in a 1-dimensional chain of nearest-neighbor coupled Kuramoto oscillators. The intrinsic frequencies and couplings are random numbers chosen from a distribution. The method is designed to work in the regime of strong randomness, where the distribution of intrinsic frequencies and couplings has long tails. Two types of decimation steps are possible: elimination of oscillators with exceptionally large frequency and renormalization of two oscillators bonded by a very large coupling into a single one. Based on these steps, we perform a numerical RG calculation. The oscillators in the renormalized chain correspond to frequency clusters. We compare the RG results with those obtained directly from the numerical solution of the chain's equations of motion.
Measuring neutrino oscillation parameters using $\
Energy Technology Data Exchange (ETDEWEB)
Backhouse, Christopher James [Oriel College, Oxford (United Kingdom)
2011-01-01
MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δm_{atm}^{2} and sin^{2} 2θ_{atm}). The oscillation signal consists of an energy-dependent deficit of v_{μ} interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the v_{μ}-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the v_{μ}-disappearance analysis, incorporating this new estimator were: Δm^{2} = 2.32_{-0.08}^{+0.12} x 10^{-3} eV^{2}, sin ^{2} 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$_{μ} beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36_{-0.40}^{+0.46}(stat.) ± 0.06(syst.)) x 10^{-3}eV^{2}, sin^{2} 2$\\bar{θ}$ = 0.86_{-0.12}^{_0}
Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators
Talukdar, Abdul Hafiz Ibne
2012-07-28
Traditionally, the necessary and sufficient condition for any system to be oscillating is that its poles are located on the imaginary (jω) axis. In this paper, for the first time, we have shown that systems can oscillate with time-domain oscillating poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating resistance and triangular shape of FFT are also demonstrated with mathematical reasoning and simulation results to support the unusual and surprising characteristics. © 2009 IEEE.
The Motion of a Leaking Oscillator: A Study for the Physics Class
Rodrigues, Hilário; Panza, Nelson; Portes, Dirceu; Soares, Alexandre
2014-01-01
This paper is essentially about the general form of Newton's second law for variable mass problems. We develop a model for describing the motion of the one-dimensional oscillator with a variable mass within the framework of classroom physics. We present a simple numerical procedure for the solution of the equation of motion of the system to…
Combustion oscillation study in a kerosene fueled rocket-based combined-cycle engine combustor
Huang, Zhi-Wei; He, Guo-Qiang; Qin, Fei; Xue, Rui; Wei, Xiang-Geng; Shi, Lei
2016-12-01
This study reports the combustion oscillation features in a three-dimensional (3D) rocket-based combined-cycle (RBCC) engine combustor under flight Mach number (Mflight) 3.0 conditions both experimentally and numerically. Experiment is performed on a direct-connect ground test facility, which measures the wall pressure along the flow-path. High-speed imaging of the flame luminosity and schlieren is carried out at exit of the primary rocket. Compressible reactive large eddy simulation (LES) with reduced chemical kinetics of a surrogate model for kerosene is performed to further understand the combustion oscillation mechanisms in the combustor. LES results are validated with experimental data by the time-averaged and root mean square (RMS) pressure values, and show acceptable agreement. Effects of the primary rocket jet on pressure oscillation in the combustor are analyzed. Relation of the high speed rocket jet oscillation, which is thought to among the most probable sources of combustion oscillation, with the RBCC combustor is recognized. Results reveal that the unsteady over-expanded rocket jet has significant impacts on the combustion oscillation feature of the RBCC combustor, which is different from a thermo-acoustics type oscillation. The rocket jet/air inflow physical interactions under different rocket jet expansion degrees are experimentally studied.
Energy Technology Data Exchange (ETDEWEB)
Decco, Claudia Cristina Ghirardello
1997-07-01
This work presents time dependent analysis of xenon spatial oscillations studying the influence of the power density distribution, type of reactivity perturbation, power level and core size, using the one-dimensional and three-dimensional analysis with the MID2 and citation codes, respectively. It is concluded that small pressurized water reactors with height smaller than 1.5 m are stable and do not have xenon spatial oscillations. (author)
Simulations of Gyrosynchrotron Microwave Emission from an Oscillating 3D Magnetic Loop
Kuznetsov, A. A.; Van Doorsselaere, T.; Reznikova, V. E.
2015-04-01
Radio observations of solar flares often reveal various periodic or quasi-periodic oscillations. Most likely, these oscillations are caused by magnetohydrodynamic (MHD) oscillations of flaring loops which modulate the emission. Interpreting the observations requires comparing them with simulations. We simulated the gyrosynchrotron radio emission from a semicircular (toroidal-shaped) magnetic loop containing sausage-mode MHD oscillations. The aim was to detect the observable signatures specific to the considered MHD mode and to study their dependence on the various source parameters. The MHD waves were simulated using a linear three-dimensional model of a magnetized plasma cylinder; both standing and propagating waves were considered. The curved loop was formed by replicating the MHD solutions along the plasma cylinder and bending the cylinder; this model allowed us to study the effect of varying the viewing angle along the loop. The radio emission was simulated using a three-dimensional model, and its spatial and temporal variations were analyzed. We considered several loop orientations and different parameters of the magnetic field, plasma, and energetic electrons in the loop. In the model with low plasma density, the intensity oscillations at all frequencies are synchronous (with the exception of a narrow spectral region below the spectral peak). In the model with high plasma density, the emission at low frequencies (where the Razin effect is important) oscillates in anti-phase with the emissions at higher frequencies. The oscillations at high and low frequencies are more pronounced in different parts of the loop (depending on the loop orientation). The layers where the line-of-sight component of the magnetic field changes sign can produce additional peculiarities in the oscillation patterns.
Bipolaron assisted Bloch-like oscillations in organic lattices
International Nuclear Information System (INIS)
Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo
2017-01-01
The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.
Bipolaron assisted Bloch-like oscillations in organic lattices
Ribeiro, Luiz Antonio; Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo
2017-06-01
The transport of a dissociated bipolaron in organic one-dimensional lattices is theoretically investigated in the scope of a tight-binding model that includes electron-lattice interactions and an external electric field. Remarkably, the results point to a physical picture in which the dissociated bipolaron propagates as a combined state of two free-like electrons that coherently perform spatial Bloch oscillations (BO) above a critical field strength. It was also obtained that the BO's trajectory presents a net forward motion in the direction of the applied electric field. The impact of dynamical disorder in the formation of electronic BOs is determined.
Oscillation matrices and kernels and small vibrations of mechanical systems
Gantmacher, F R
2002-01-01
Fifty years after the original Russian Edition, this classic work is finally available in English for the general mathematical audience. This book lays the foundation of what later became "Krein's Theory of String". The original ideas stemming from mechanical considerations are developed with exceptional clarity. A unique feature is that it can be read profitably by both research mathematicians and engineers. The authors study in depth small oscillations of one-dimensional continua with a finite or infinite number of degrees of freedom. They single out an algebraic property responsible for the
Frequency Mixing of Magnetic Oscillations: Beyond Falicov-Stachowiak Theory
Fortin, Jean-Yves; Ziman, Timothy
1998-04-01
The interpretation of de Haas-van Alphen oscillations in the presence of magnetic breakdown is usually based on the semiclassical theory of Falicov and Stachowiak (FS). There are now glaring discrepancies between its predictions and experiments, especially in quasi-two-dimensional organic conductors. We present an extension of the theory, using the appropriate constraints of conserved electron density, which explains the occurrence of frequencies not predicted by FS, and makes explicit the amplitudes as a function of Fermi surface parameters. The results involve a tunneling amplitude between different sheets as in FS, but other parameters as well, such as the areas of different orbits.
Thermoelastic loss in microscale oscillators
Houston, B. H.; Photiadis, D. M.; Marcus, M. H.; Bucaro, J. A.; Liu, Xiao; Vignola, J. F.
2002-02-01
A simple model of thermoelastic dissipation is proposed for general, free standing microelectromechanical (MEMS) and nanoelectromechanical (NEMS) oscillators. The theory defines a flexural modal participation factor, the fraction of potential energy stored in flexure, and approximates the internal friction by assuming the energy loss to occur solely via classical thermoelastic dissipation of this component of the motion. The theory is compared to the measured internal friction of a high Q mode of a single-crystal silicon double paddle oscillator. The loss at high temperature (above 150 K) is found to be in good agreement with the theoretical prediction. The importance of this dissipation mechanism as a function of scale is briefly discussed. We find that the relative importance of this mechanism scales with the size of the structure, and that for nanoscale structures it is less important than intrinsic phonon-phonon scattering.
Neuronal oscillations in Parkinson's disease.
Witcher, Mark; Moran, Rosalyn; Tatter, Stephen B; Laxton, Adrian W
2014-06-01
Parkinson's Disease (PD), characterized by tremor, rigidity, and bradykinesia, is one of the most prevalent neurodegenerative disorders in the world. The pathological hallmark of PD is the loss of dopaminergic cells in the substantia nigra and other brain regions. The pathophysiological mechanisms by which dopaminergic cell loss leads to the motor manifestations of PD are yet to be fully elucidated. A growing body of evidence has revealed abnormal neuronal oscillations within and between multiple brain regions in PD. Unique oscillatory patterns are associated with specific motor abnormalities in PD. Therapies, such as dopaminergic medication and deep brain stimulation that disrupt these abnormal neuronal oscillatory patterns produce symptomatic improvement in PD patients. These findings emphasize the importance of abnormal neuronal oscillations in the pathophysiology of PD, making the disruption of these oscillatory patterns a promising target in the development of effective PD treatments.
Experimental studies of neutrino oscillations
Kajita, Takaaki
2016-01-01
The 2015 Nobel Prize in physics has been awarded to Takaaki Kajita and Arthur McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita of Tokyo University is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into as well as a record of the rise and the role of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the 3 families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible foot-print in the history of big and better science.
Two-dimensional phase contrast MR angiography of the venous system of lower extremities
International Nuclear Information System (INIS)
Hashimoto, Hiromi; Nakatsuka, Haruki; Tsubakimoto, Mitsuo
1994-01-01
Two-dimensional phase contrast MR angiography (MRA) was performed in 10 healthy volunteers and 14 patients in whom deep venous occlusion was clinically suspected. In all volunteers, MRA demonstrated bilateral great saphenous veins, superficial femoral veins and popliteal veins. Deep veins in the calves were visualized in only 3 of 20 legs (15%) examined, but after applying tourniquets above the knee, they were visualized in 6 of 8 legs (75%). In 5 of 8 patients whose lower extremities were swollen, deep vein occlusions were diagnosed by MRA and in 4 patients deep vein thrombosis was confirmed by computed tomography or conventional venography. In the other 3 patients whose lower extremities were swollen and in 6 patients whose lower extremities were not swollen but who had varicose veins, MRA demonstrated patency of the deep veins. It is concluded that MRA is a non-invasive useful diagnostic technique for evaluating patency of the deep venous system of the lower extremities. (author)
Two-dimensional phase contrast MR angiography of the venous system of lower extremities
Energy Technology Data Exchange (ETDEWEB)
Hashimoto, Hiromi; Nakatsuka, Haruki; Tsubakimoto, Mitsuo (Itami City Hospital, Hyogo (Japan)) (and others)
1994-01-01
Two-dimensional phase contrast MR angiography (MRA) was performed in 10 healthy volunteers and 14 patients in whom deep venous occlusion was clinically suspected. In all volunteers, MRA demonstrated bilateral great saphenous veins, superficial femoral veins and popliteal veins. Deep veins in the calves were visualized in only 3 of 20 legs (15%) examined, but after applying tourniquets above the knee, they were visualized in 6 of 8 legs (75%). In 5 of 8 patients whose lower extremities were swollen, deep vein occlusions were diagnosed by MRA and in 4 patients deep vein thrombosis was confirmed by computed tomography or conventional venography. In the other 3 patients whose lower extremities were swollen and in 6 patients whose lower extremities were not swollen but who had varicose veins, MRA demonstrated patency of the deep veins. It is concluded that MRA is a non-invasive useful diagnostic technique for evaluating patency of the deep venous system of the lower extremities. (author).
Memristor-based reactance-less oscillator
Zidan, Mohammed A.
2012-10-02
The first reactance-less oscillator is introduced. By using a memristor, the oscillator can be fully implemented on-chip without the need for any capacitors or inductors, which results in an area-efficient fully integrated solution. The concept of operation of the proposed oscillator is explained and detailed mathematical analysis is introduced. Closed-form expressions for the oscillation frequency and oscillation conditions are derived. Finally, the derived equations are verified with circuit simulations showing excellent agreement. © 2011 The Institution of Engineering and Technology.
Quantum oscillations of conductivity in bismuth wires
International Nuclear Information System (INIS)
Condrea, Elena
2011-01-01
Measurements of the resistance of bismuth nanowires with several diameters and different quality reveal oscillations on the dependence of resistance under uniaxial strain at T = 4.2 K. Amplitude of oscillations is significant (38 %) at helium temperature and becomes smearing at T = 77 K. Observed oscillations originate from quantum size effect. A simple evaluation of period of oscillations allows us to identify the groups of carriers involved in transport. Calculated periods of 42.2 and 25.9 nm satisfy approximately the ratio 2:1 for two experimentally observed sets of oscillations from light and heavy electrons.
Harmonic oscillator and nuclear pseudospin
International Nuclear Information System (INIS)
Lisboa, Ronai; Malheiro, Manuel; Castro, Antonio S. de; Alberto, Pedro; Fiolhais, Manuel
2004-01-01
A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonian contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U, linear in r. Setting either Σ = S + V or Δ = V - S to zero, analytical solutions for bound states are found. The eingenenergies and their nonrelativistic limits are presented and particular cases are discussed, especially the case Σ = 0, for which pseudospin symmetry is exact
Global Status of Neutrino Oscillation
Indian Academy of Sciences (India)
monojit
Number Games. The defining element in the oscillation (or survival probability) is sin. 2. ∆m2. 21L/(4E) ≡ sin. 2. 1.27(∆m2. 21eV. 2) ((L/E)km/GeV OR m/MeV). .... The 90% CL contours with 10 years' simulated ICAL in comparison with results ... Simulation showing improvement in sensitivity to the unknown CP phase.
Harmonic oscillator on a lattice
International Nuclear Information System (INIS)
Ader, J.P.; Bonnier, B.; Hontebeyrie, M.; Meyers, C.
1983-01-01
The continuum limit of the ground state energy for the harmonic oscillator with discrete time is derived for all possible choices of the lattice derivative. The occurrence of unphysical values is shown to arise whenever the lattice laplacian is not strictly positive on its Brillouin zone. These undesirable limits can either be finite and arbitrary (multiple spectrum) or infinite (overlapping sublattices with multiple spectrum). (orig.)
Lepton asymmetries from neutrino oscillations
International Nuclear Information System (INIS)
Volkas, R.R.
2000-01-01
Reasonably large relic neutrino asymmetries can be generated by active-sterile neutrino oscillations. After briefly discussing possible applications, I describe the Quantum Kinetic Equation formalism used to compute the asymmetry growth curves. I then show how the basic features of these curves can be understood on the basis of the adiabatic limit approximation in the collision dominated epoch, and the pure MSW effect at lower temperatures (author)
Coherence effects in neutrino oscillations
International Nuclear Information System (INIS)
Kiers, K.; Weiss, N.
1996-01-01
We study the effect of coherent and incoherent broadening on neutrino oscillations both in vacuum and in the presence of matter (the MSW effect). We show under very general assumptions that it is not possible to distinguish experimentally neutrinos produced in some region of space as wave packets from those produced in the same region of space as plane waves with the same energy distribution. copyright 1995 The American Physical Society
Oscillations and Waves in Sunspots
Directory of Open Access Journals (Sweden)
Elena Khomenko
2015-11-01
Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.
Neutrino Oscillation Experiment at JHF
2002-01-01
T2K is a long baseline neutrino experiment designed to investigate how neutrinos change from one flavor to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K, 295 km away: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos. The high intensity neutrino beam is produced in an off-axis configuration. The peak neutrino energy is tuned to the oscillation maximum of ∼ 0.6 GeV to maximize the sensitivity to neutrino oscillations. The science goals of T2K can be summarized as follows: •\tsearch for CP violation in the neutrino sector •\tdiscovery of νμ → νe ( i.e. the confirmation that θ13 > 0 ) •\tprecision ...
Drifting oscillations in axion monodromy
International Nuclear Information System (INIS)
Flauger, Raphael; Westphal, Alexander
2014-12-01
We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.
Micro-machined resonator oscillator
Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.
1994-01-01
A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.
Drifting oscillations in axion monodromy
Energy Technology Data Exchange (ETDEWEB)
Flauger, Raphael [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); McAllister, Liam [Department of Physics, Cornell University, Ithaca, NY 14853 (United States); Silverstein, Eva [Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305 (United States); Westphal, Alexander, E-mail: flauger@physics.ucsd.edu, E-mail: mcallister@cornell.edu, E-mail: evas@stanford.edu, E-mail: alexander.westphal@desy.de [Theory Group, Deutsches Elektronen-Synchrotron DESY, D-22603 Hamburg (Germany)
2017-10-01
We study the pattern of oscillations in the primordial power spectrum in axion monodromy inflation, accounting for drifts in the oscillation period that can be important for comparing to cosmological data. In these models the potential energy has a monomial form over a super-Planckian field range, with superimposed modulations whose size is model-dependent. The amplitude and frequency of the modulations are set by the expectation values of moduli fields. We show that during the course of inflation, the diminishing energy density can induce slow adjustments of the moduli, changing the modulations. We provide templates capturing the effects of drifting moduli, as well as drifts arising in effective field theory models based on softly broken discrete shift symmetries, and we estimate the precision required to detect a drifting period. A non-drifting template suffices over a wide range of parameters, but for the highest frequencies of interest, or for sufficiently strong drift, it is necessary to include parameters characterizing the change in frequency over the e-folds visible in the CMB. We use these templates to perform a preliminary search for drifting oscillations in a part of the parameter space in the Planck nominal mission data.
Mourokh, L.; Wixforth, A.; Beil, F.; Bichler, M.; Wegscheider, W.; Blick, R. H.
2017-10-01
A quantum dot is created within a suspended nanobridge containing a two-dimensional electron gas. The electron current through this dot exhibits well-pronounced Coulomb blockade oscillations. When surface acoustic waves (SAW) are driven through the nanobridge, Coulomb blockade peaks are shifted. To explain this feature, we derive the expressions for the quantum dot level populations and electron currents through these levels and show that SAW-induced Rabi oscillations lead to the observed phenomenology.
Directory of Open Access Journals (Sweden)
Jorge Enrique Soracco
2005-01-01
Full Text Available OBJETIVO: O objetivo do presente estudo é relatar as complicações no tratamento de varizes em membros inferiores com laser endovascular. MÉTODOS: Foram levantadas, no período de junho de 1999 a dezembro de 2002, algumas complicações, como queimadura de pele, neurite do nervo safeno, hiperpigmentação e fibrose no local da safena em 250 pacientes submetidos a tratamento endovascular com laser em varizes de membros inferiores. O diagnóstico das complicações foi clínico e baseado nos sinais e sintomas. Avaliou-se 196 pacientes do sexo feminino e 54 do sexo masculino, com idades variando entre 25 e 79 anos, no Hospital Militar de Buenos Aires. Foram tratados com laser de diodo de alta potência de 810 nm de longitude de onda mediante um sistema de fibras óticas semi-rígidas de quartzo de 400 e 600 µm e ponta de contato plana em modo cirúrgico contínuo. Para análise estatística, foram calculadas as percentagens. RESULTADOS: Lesões tipo queimadura foram observadas em 3,2%, hiperpigmentação em 9,6%, fibrose no local da safena por mais de 6 meses em 5,6% e neurite do nervo safeno em 4,8%. CONCLUSÃO: Conclui-se que o tratamento com laser endovascular de varizes de membros inferiores não é desprovido de intercorrências e que os fatores que levaram a essas complicações devem ser identificados e reavaliados.OBJECTIVE: The aim of the present study is to report the complications seen in the endovascular laser treatment of varicose veins of the lower limbs. METHODS: From June 1999 to December 2002, 250 patients submitted to the endovascular treatment of varicose veins of the lower limbs using lasers and suffering from complications, such as skin burns, saphenous neuritis, hyperpigmentation and fibrosis along the course of the saphenous vein, were assessed. The diagnosis of the complications was made clinically based on the signs and symptoms evidenced. Of the 250 patients, aged 25-79 years, treated in the Hospital Militar de Buenos
Pegna, R.; Nobili, A. M.; Shao, M.; Turyshev, S. G.; Catastini, G.; Anselmi, A.; Spero, R.; Doravari, S.; Comandi, G. L.; de Michele, A.
2011-11-01
Mechanical oscillators can be sensitive to very small forces. Low frequency effects are up-converted to higher frequency by rotating the oscillator. We show that for 2-dimensional oscillators rotating at frequency much higher than the signal the thermal noise force due to internal losses and competing with it is abated as the square root of the rotation frequency. We also show that rotation at frequency much higher than the natural one is possible if the oscillator has 2 degrees of freedom, and describe how this property applies also to torsion balances. In addition, in the 2D oscillator the signal is up-converted above resonance without being attenuated as in the 1D case, thus relaxing requirements on the read out. This work indicates that proof masses weakly coupled in 2D and rapidly rotating can play a major role in very small force physics experiments.
Excitation and damping of transversal oscillation in coronal loops by wake phenomena
Directory of Open Access Journals (Sweden)
A abedini
2018-02-01
Full Text Available Transversal oscillation of coronal loops that are interpreted as signatures of magneto hydrodynamics (MHD waves are observed frequently in active region corona loops. The amplitude of this oscillation has been found to be strongly attenuated. The damping of transverse oscillation may be produced by the dissipation mechanism and the wake of the traveling disturbance. The damping of transversal loop oscillations with wake phenomena is not related to any dissipation mechanism. Also, these kinds of coronal loop oscillations are not related to the kink mode, although this mode can be occurred after the attenuation process by the energy of the wave packet deposited in the loop. In this paper the excitation and damping of transversal coronal loop oscillations with wake of traveling wave packet is discussed in detail, both theoretically and observationally. Here, the transversal coronal loop oscillations is modeled with a one dimensional simple line-tied. The dynamics of the loop and the coronal is governed by the Klein–Gordon differential equation. A localized disturbance that can be generated by nearby flare produces a perturbation that undergoes dispersion as it propagates toward the loop. As a consequence, the amplitudes of oscillates decay with time roughly t-1/2 at the external cutoff frequency. These observed data on 2016-Dec-4 by Atmospheric Imaging Assembly (AIA onboard Solar Dynamic Observatory (SDO observations data, consisting of 560 images with an interval of 24 seconds in the 171 A0 pass band is analyzed for evidence of excitation and damping of transverse oscillations of coronal loop that is situated near a flare. In this analyzed signatures of transverse oscillations that are damped rapidly were found, with periods in the range of P=18.5-23.85 minutes. Furthermore, oscillation of loop segments attenuate with time roughly as t-α that average values of α for 4 different loops change form 0.65-0.80. The magnitude values of α are in
Directory of Open Access Journals (Sweden)
Qinghua Wu
2015-01-01
equivalent to the GMRES method proposed by Olver (2009. Moreover, the simpler GMRES does not require upper Hessenberg matrix factorization, which leads to much simpler program and requires less work. Numerical experiments are conducted to illustrate the performance of the new method and show that in some cases the simpler GMRES method could achieve higher accuracy than GMRES.
Magneto-elastic oscillations modulating the emission of magnetars
Gabler, M.; Cerdá-Durán, P.; Mate, A.; Stergioulas, N.; Font, J. A.; Müller, E.
2017-12-01
Magneto-elastic oscillations of neutron stars are believed to explain observed quasi-periodic oscillations (QPOs) in the decaying tail of the giant flares of highly magnetized neutron stars (magnetars). Strong efforts of the theoretical modelling from different groups have increased our understanding of this phenomenon significantly. Here, we discuss some constraints on the matter in neutron stars that arise if the interpretation of the observations in terms of superfluid, magneto-elastic oscillations is correct. To explain the observed modulation of the light curve of the giant flare, we describe a model that allows the QPOs to couple to the stellar exterior through the magnetic field. In this magnetosphere, the shaking magnetic field induces currents that provide scattering targets for resonant cyclotron scattering of photons, which is calculated with a Monte-Carlo approach and coupled to a code that calculates the momentum distribution of the charge carriers as a one-dimensional accelerator problem. We show first results of a simplified, but self-consistent momentum distribution, i.e. a waterbag distribution, and of the corresponding spectra.
Eigenmode analysis of coupled magnetohydrodynamic oscillations in the magnetosphere
International Nuclear Information System (INIS)
Fujita, S.; Patel, V.L.
1992-01-01
The authors have performed an eigenmode analysis of the coupled magnetohydrodynamic oscillations in the magnetosphere with a dipole magnetic field. To understand the behavior of the spatial structure of the field perturbations with a great accuracy, they use the finite element method. The azimuthal and radial electric field perturbations are assumed to vanish at the ionosphere, and the azimuthal electric field is assumed to be zero on the outer boundary. The global structures of the electromagnetic field perturbations associated with the coupled magnetohydrodynamic oscillations are presented. In addition, the three-dimensional current system associated with the coupled oscillations is numerically calculated and the following characteristics are found: (1) A strong field-aligned current flows along a resonant field line. The current is particularly strong near the ionosphere. (2) The radial current changes its direction on the opposite sides of the resonant L shell. Unlike the field-aligned current, the radial currents exist in the entire magnetosphere. (3) Although the azimuthal and radial currents are intense on the resonant field line, these currents do not form a loop in the plane perpendicular to the ambient magnetic field. Therefore the field-aligned component of the perturbed magnetic field does not have a maximum at the resonant L shell
Competition for synchronization in a phase oscillator system
Kazanovich, Yakov; Burylko, Oleksandr; Borisyuk, Roman
2013-10-01
A system of phase oscillators with a Central Oscillator (CO) and a set of n Peripheral Oscillators (POs) is considered. Feed-forward and feedback connections between the CO and POs are determined by two interaction functions which are assumed to be smooth, odd, and periodic. To describe the competition of POs for synchronization with the CO, we study the asymptotic stability of fixed points corresponding to in-phase synchronization of a group of k POs, while other POs are in anti-phase with the CO. It is shown that stability conditions can be formulated in terms of four parameters that describe the slopes of the interaction functions at zero and half-period points. Analytical description of stability in terms of the regions in 4-dimensional parameter space is given. Combining stability analysis with the detailed study of geometry of invariant manifolds, the bifurcations of fixed points are investigated. We show that various dynamical regimes such as multistability, heteroclinic orbits, and chaos are possible. Analytical stability conditions for global synchronization of POs with the CO are formulated for the systems with local connections between POs. It is shown that synchronization in a large system with local connections becomes unstable even under weak desynchronizing influence from the CO. The application of the results to modeling in neuroscience and, in particular, for modeling visual attention is discussed.
Sea ice inertial oscillations in the Arctic Basin
Directory of Open Access Journals (Sweden)
F. Gimbert
2012-10-01
Full Text Available An original method to quantify the amplitude of inertial motion of oceanic and ice drifters, through the introduction of a non-dimensional parameter M defined from a spectral analysis, is presented. A strong seasonal dependence of the magnitude of sea ice inertial oscillations is revealed, in agreement with the corresponding annual cycles of sea ice extent, concentration, thickness, advection velocity, and deformation rates. The spatial pattern of the magnitude of the sea ice inertial oscillations over the Arctic Basin is also in agreement with the sea ice thickness and concentration patterns. This argues for a strong interaction between the magnitude of inertial motion on one hand, the dissipation of energy through mechanical processes, and the cohesiveness of the cover on the other hand. Finally, a significant multi-annual evolution towards greater magnitudes of inertial oscillations in recent years, in both summer and winter, is reported, thus concomitant with reduced sea ice thickness, concentration and spatial extent.
Acoustic streaming induced by an ultrasonically oscillating endodontic file.
Verhaagen, B; Boutsioukis, C; van der Sluis, L W M; Versluis, M
2014-04-01
Ultrasonically activated irrigation is an advanced dental technique for irrigation of the root canal system during a root canal treatment. The basic cleaning mechanism is a result of acoustic streaming induced by an oscillating file, leading to mixing of the irrigant and pressure and shear stresses on the walls of the root canal. Here the induced acoustic streaming, pressure, and shear stress are investigated in a two-dimensional cross-section of the root canal, using a combination of theory, numerical predictions, and experimental validation through high-speed particle tracking velocimetry. Acoustic streaming theory describes very well the flow induced by an ultrasonically oscillating endodontic file. It consists of an oscillatory component, which is dominant near the file, and a steady component, or jet, along the axis of oscillation. The importance of the oscillatory component for both the pressure and the shear stress is apparent, as it is two to three orders of magnitude higher than the steady component. A confinement affects the formation of the steady jets; meanwhile the oscillatory velocities and associated pressure and shear stress are increased. Previous work considering only the steady component of the flow therefore, underestimated the hydrodynamic effects induced by ultrasonic files.
Magnetic oscillations measure interlayer coupling in cuprate superconductors
Grigoriev, P. D.; Ziman, Timothy
2017-10-01
The magnetic oscillations in YBCO high-temperature superconductors have been widely studied over the last decade and consist of three equidistant low frequencies with a central frequency several times more intense than its two shoulders. This remains a puzzle in spite of numerous attempts to explain the corresponding small Fermi-surface pockets. Furthermore, the ARPES data indicate only four Fermi arcs with bilayer splitting, and show no sign of such small areas in the Fermi surface. Here we argue that the magnetic oscillations measured in underdoped bilayer high-temperature superconductors, in particular YBa2Cu3O6 +δ , provide a measure of the interplanar electronic coupling rather than the areas of fine-grain reconstruction of the Fermi surfaces coming from induced charge density waves. This identification is based on the relative intensities of the different peaks, as well as their angular dependence, which points to an effective Fermi surface that is larger than the oscillation frequencies, and is compatible with several indications from ARPES. The dominance of such frequencies with respect to the fundamental frequencies from the Fermi surface is natural for a strongly correlated quasi-two-dimensional electronic system where nonlinear mixings of frequencies are more resistant to sample inhomogeneity.
Energetics and optimum motion of oscillating lifting surfaces. [energy losses of rigid wings
Ahmadi, A. R.; Widnall, S. E.
1983-01-01
Low-frequency, unsteady, lifting-line theory is used to characterize the energetics and optimum motion of an unswept rigid wing oscillating harmonically in an inviscid, incompressible flow. The energetics calculations account for the leading edge suction force, the power absorbed in the wing oscillations, and the energy loss rate produced by vortex shedding. Optimization is achieved by minimizing the average energy loss rate in relation to a given thrust, and a unique solution is found in the three dimensional case for low, reduced frequencies. The two-dimensional solution is nonunique, a condition which is examined in terms of the normal modes of the energy loss rate matrix. An invisible mode with a hydrodynamic efficiency of 100 pct is obtained in the two-dimensional case, causing the nonuniqueness of the solution by yielding no fixed positive thrust through perfect unsteady feathering.
Separation control with fluidic oscillators in water
Schmidt, H.-J.; Woszidlo, R.; Nayeri, C. N.; Paschereit, C. O.
2017-08-01
The present study assesses the applicability of fluidic oscillators for separation control in water. The first part of this work evaluates the properties of the fluidic oscillators including frequency, cavitation effects, and exerted thrust. Derived from the governing internal dynamics, the oscillation frequency is found to scale directly with the jet's exit velocity and the size of the fluidic oscillator independent of the working fluid. Frequency data from various experiments collapse onto a single curve. The occurrence of cavitation is examined by visual inspection and hydrophone measurements. The oscillation frequency is not affected by cavitation because it does not occur inside the oscillators. The spectral information obtained with the hydrophone provide a reliable indicator for the onset of cavitation at the exit. The performance of the fluidic oscillators for separation control on a bluff body does not seem to be affected by the presence of cavitation. The thrust exerted by an array of fluidic oscillators with water as the working fluid is measured to be even larger than theoretically estimated values. The second part of the presented work compares the performance of fluidic oscillators for separation control in water with previous results in air. The array of fluidic oscillators is installed into the rear end of a bluff body model. The drag improvements based on force balance measurements agree well with previous wind tunnel experiments on the same model. The flow field is examined by pressure measurements and with particle image velocimetry. Similar performance and flow field characteristics are observed in both water and air.
Indian Academy of Sciences (India)
Dimensional analysis is a useful tool which finds important applications in physics and engineering. It is most effective when there exist a maximal number of dimensionless quantities constructed out of the relevant physical variables. Though a complete theory of dimen- sional analysis was developed way back in 1914 in a.
Indian Academy of Sciences (India)
to understand and quite straightforward to use. Dimensional analysis is a topic which every student of 'science encounters in elementary physics courses. The basics of this topic are taught and learnt quite hurriedly (and forgotten fairly quickly thereafter!) It does not generally receive the attention and the respect it deserves ...
DEFF Research Database (Denmark)
Carlsen, Bent Erik; Jensen, Bjarne Chr.; Olesen, Frits Bolonius
grundlag for at vurdere, om - og i givet fald hvordan - brandteknisk dimensionering af bærende konstruktioner vil kunne indføres i DIF's konstruktionsnormer, indeholder et skitseforslag til, efter hvilke principper dette vil kunne gøres. Men derudover har udvalget i fire dataoplæg (rapportens bilag 1...
Clusters in nonsmooth oscillator networks
Nicks, Rachel; Chambon, Lucie; Coombes, Stephen
2018-03-01
For coupled oscillator networks with Laplacian coupling, the master stability function (MSF) has proven a particularly powerful tool for assessing the stability of the synchronous state. Using tools from group theory, this approach has recently been extended to treat more general cluster states. However, the MSF and its generalizations require the determination of a set of Floquet multipliers from variational equations obtained by linearization around a periodic orbit. Since closed form solutions for periodic orbits are invariably hard to come by, the framework is often explored using numerical techniques. Here, we show that further insight into network dynamics can be obtained by focusing on piecewise linear (PWL) oscillator models. Not only do these allow for the explicit construction of periodic orbits, their variational analysis can also be explicitly performed. The price for adopting such nonsmooth systems is that many of the notions from smooth dynamical systems, and in particular linear stability, need to be modified to take into account possible jumps in the components of Jacobians. This is naturally accommodated with the use of saltation matrices. By augmenting the variational approach for studying smooth dynamical systems with such matrices we show that, for a wide variety of networks that have been used as models of biological systems, cluster states can be explicitly investigated. By way of illustration, we analyze an integrate-and-fire network model with event-driven synaptic coupling as well as a diffusively coupled network built from planar PWL nodes, including a reduction of the popular Morris-Lecar neuron model. We use these examples to emphasize that the stability of network cluster states can depend as much on the choice of single node dynamics as it does on the form of network structural connectivity. Importantly, the procedure that we present here, for understanding cluster synchronization in networks, is valid for a wide variety of systems in
International Nuclear Information System (INIS)
Yamasita, Kiyonobu; Harada, Hiroo; Murata, Isao; Shindo, Ryuichi; Tsuruoka, Takuya.
1993-01-01
Xenon oscillations of large graphite-moderated reactors have been analyzed by a multi-group diffusion code with two- and three-dimensional core models to study the effects of the geometric core models and the neutron energy group structures on the evaluation of the Xe oscillation behavior. The study clarified the following. It is important for accurate Xe oscillation simulations to use the neutron energy group structure that describes well the large change in the absorption cross section of Xe in the thermal energy range of 0.1∼0.65 eV, because the energy structure in this energy range has significant influences on the amplitude and the period of oscillations in power distributions. Two-dimensional R-Z models can be used instead of three-dimensional R-θ-Z models for evaluation of the threshold power of Xe oscillation, but two-dimensional R-θ models cannot be used for evaluation of the threshold power. Although the threshold power evaluated with the R-θ-Z models coincides with that of the R-Z models, it does not coincide with that of the R-θ models. (author)
Harmonic oscillator and nuclear pseudospin
International Nuclear Information System (INIS)
Lisboa, Ronai; Malheiro, Manuel; Castro, Antonio S. de; Alberto, Pedro; Fiolhais, M.
2004-01-01
A generalized relativistic harmonic oscillator for spin 1/2 particles is studied. The Dirac Hamiltonians contains a scalar S and a vector V quadratic potentials in the radial coordinate, as well as a tensor potential U, linear in r. Setting either Σ=S+V or Δ=V - S to zero, analytical solutions for bound states are found. The eigenenergies and their nonrelativistic limits are present and particular cases are discussed, especially the case Σ=0, for which pseudospin symmetry is exact. (author)
Wave Physics Oscillations - Solitons - Chaos
Nettel, Stephen
2009-01-01
This textbook is intended for those second year undergraduates in science and engineering who will later need an understanding of electromagnetic theory and quantum mechanics. The classical physics of oscillations and waves is developed at a more advanced level than has been customary for the second year, providing a basis for the quantum mechanics that follows. In this new edition the Green's function is explained, reinforcing the integration of quantum mechanics with classical physics. The text may also form the basis of an "introduction to theoretical physics" for physics majors. The concluding chapters give special attention to topics in current wave physics: nonlinear waves, solitons, and chaotic behavior.
Pair creation and plasma oscillations
International Nuclear Information System (INIS)
We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background fields and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses
Making space for harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, Leo; /Fermilab
2004-11-01
If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.
Relaxation Oscillation and Canard Explosion
Krupa, M.; Szmolyan, P.
2001-08-01
We give a geometric analysis of relaxation oscillations and canard cycles in singularly perturbed planar vector fields. The transition from small Hopf-type cycles to large relaxation cycles, which occurs in an exponentially thin parameter interval, is described as a perturbation of a family of singular cycles. The results are obtained by means of two blow-up transformations combined with standard tools of dynamical systems theory. The efficient use of various charts is emphasized. The results are applied to the van der Pol equation.
Directory of Open Access Journals (Sweden)
M. Schulz
2007-01-01
Full Text Available Using a 3-dimensional climate model of intermediate complexity we show that the overturning circulation of the Atlantic Ocean can vary at multicentennial-to-millennial timescales for modern boundary conditions. A continuous freshwater perturbation in the Labrador Sea pushes the overturning circulation of the Atlantic Ocean into a bi-stable regime, characterized by phases of active and inactive deep-water formation in the Labrador Sea. In contrast, deep-water formation in the Nordic Seas is active during all phases of the oscillations. The actual timing of the transitions between the two circulation states occurs randomly. The oscillations constitute a 3-dimensional phenomenon and have to be distinguished from low-frequency oscillations seen previously in 2-dimensional models of the ocean. A conceptual model provides further insight into the essential dynamics underlying the oscillations of the large-scale ocean circulation. The model experiments indicate that the coupled climate system can exhibit unforced climate variability at multicentennial-to-millennial timescales that may be of relevance for Holocene climate variations.
Phase noise and frequency stability in oscillators
Rubiola, Enrico
2009-01-01
Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...
Driven, autoresonant three-oscillator interactions
International Nuclear Information System (INIS)
Yaakobi, O.; Friedland, L.; Henis, Z.
2007-01-01
An efficient control scheme of resonant three-oscillator interactions using an external chirped frequency drive is suggested. The approach is based on formation of a double phase-locked (autoresonant) state in the system, as the driving oscillation passes linear resonance with one of the interacting oscillators. When doubly phase locked, the amplitudes of the oscillators increase with time in proportion to the driving frequency deviation from the linear resonance. The stability of this phase-locked state and the effects of dissipation and of the initial three-oscillator frequency mismatch on the autoresonance are analyzed. The associated autoresonance threshold phenomenon in the driving amplitude is also discussed. In contrast to other nonlinear systems, driven, autoresonant three-oscillator excitations are independent of the sign of the driving frequency chirp rate
Damping elastic oscillations of digging mechanism
Kuznetsov, N. K.; Makhno, D. E.; Iov, I. A.
2017-10-01
The article studies methods for reducing dynamic loading and elastic oscillations of excavator buckets using dampers. The authors suggest a structural scheme for damping bucket oscillations using a damping device installed in a running gear of the traction cable. The results of numerical efficiency simulation are presented. The article shows that the system helps to reduce intensity of elastic oscillations and a transition period in acceleration and deceleration modes.
Oscillations of neutral B mesons systems
Boucrot, J.
1999-01-01
The oscillation phenomenon in the neutral B mesons systems is now well established. The motivations and principles of the measurements are given; then the most recent results from the LEP experiments, the CDF collaboration at Fermilab and the SLD collaboration at SLAC are reviewed. The present world average of the $\\bd$ meson oscillation frequency is $\\dmd = 0.471 \\pm 0.016 \\ps$ and the lower limit on the $\\bs$ oscillation frequency is
Synchronization of weakly coupled canard oscillators
Köksal Ersöz, Elif; Desroches, Mathieu; Krupa, Martin
2017-01-01
International audience; Synchronization has been studied extensively in the context of weakly coupled oscillators using the so-called phase response curve (PRC) which measures how a change of the phase of an oscillator is affected by a small perturbation. This approach was based upon the work of Malkin, and it has been extended to relaxation oscillators. Namely, synchronization conditions were established under the weak coupling assumption, leading to a criterion for the existence of synchron...
Humeau-Heurtier, Anne; Klonizakis, Markos
2015-06-01
The diagnosis of pathologies from signal processing approaches has shown to be of importance. This can provide noninvasive information at the earliest stage. In this work, the problem of categorising - in a quantifiable manner - information content of microvascular blood flow signals recorded in healthy participants and patients with varicose veins is addressed. For this purpose, laser Doppler flowmetry (LDF) signals - that reflect microvascular blood flow - recorded both at rest and after acetylcholine (ACh) stimulation (an endothelial-dependent vasodilator) are analyzed. Each signal is processed with the empirical mode decomposition (EMD) to obtain its intrinsic mode functions (IMFs). An entropy measure of each IMFs is then computed. The results show that IMFs of LDF signals have different complexity for different physiologic/pathological states. This is true both at rest and after ACh stimulation. Thus, the proposed framework (EMD + entropy computation) may be used to gain a noninvasive understanding of LDF signals in patients with microvascular dysfunctions. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.
Energy Technology Data Exchange (ETDEWEB)
Kluner, C.; Fischer, T.; Filimonow, S.; Hamm, B.; Kroencke, T. [Inst. fuer Radiologie, Charite Univ. Berlin, Campus Mitte (Germany)
2005-02-01
Endovenous laser therapy (EVLT) is a new, minimally invasive therapeutic option for treating primary varicose veins and provides an effective and safe alternative to conventional surgical management (stripping). Short-term and intermediate-term outcome is comparable to surgical stripping in terms of elimination of venous reflux (90% - 98%), resolution of visible varices (85%), and improvement of subjective complaints such as sensations of heaviness and tension (96%). Complications occur in 1% - 3% of cases, which is markedly below the rate of conventional surgical management (up to 30%). The intermediate-term incidence of recurrent varicosis in a vein treated by EVLT depends on the laser fluence applied and is reported to range from 7% - 9% compared to 10% - 20% after surgical intervention. Based on a review of the current literature and our own experience, this survey article presents an overview of the indications and contraindications, the technique and pathophysiology of laser-induced venous occlusion, and the results and possible complications of EVLT. (orig.)
Directory of Open Access Journals (Sweden)
Luiz Marcelo Aiello Viarengo
2006-09-01
Full Text Available OBJETIVO: Avaliar os resultados da terapêutica endovenosa com laser no tratamento de varizes primárias. PACIENTES E MÉTODO: No período compreendido entre julho de 2001 e setembro de 2004 (39 meses, 253 pacientes (417 membros foram tratados ambulatorialmente com laser de diodo de 810 e 980-nm, com energia liberada endovenosamente através de fibra óptica introduzida por punção guiada por eco-Doppler. Foi utilizada anestesia por infiltração intumescente perivasal com solução de lidocaína a 0,2% (50-150 ml. A potência e duração do pulso foram determinadas pelo diâmetro da veia. Os controles foram realizados com eco-Doppler aos 7 dias, 1 mês, 3 meses, 6 meses, 1 ano e, a seguir, anualmente, para avaliar a eficácia do tratamento e os efeitos adversos. RESULTADOS: A oclusão primária da veia safena magna foi obtida em 405 dos 417 membros (97,1% tratados. Houve reintervenção em 12 casos (2,9%, com sucesso. O tempo médio de observação foi de 18 meses, e, nesse período, a taxa de recidiva global de varizes foi de 7,4%, sendo 6,3% (26 membros veias colaterais tributárias da crossa e 1,2% (cinco membros com recanalização da safena magna. Todas as recorrências ocorreram entre o terceiro e o 12º mês. Os efeitos indesejáveis mais freqüentes foram: equimoses (60,6%; dor suportável durante o procedimento (16,1%; hematomas (5,5%; flebite em colaterais não-tratadas (3,4%; hiperpigmentação (2,9%; e parestesia transitória (3,4%. Nenhum caso de tromboflebite da safena magna foi observado. Não houve nenhum caso de trombose venosa profunda ou embolia pulmonar. CONCLUSÃO: O tratamento endovenoso de varizes com laser, conforme descrito, foi eficaz para ocluir a safena magna e seus principais ramos, com efeitos adversos autolimitados e com recorrência inferior a 8% no período de seguimento.OBJETIVE: To evaluate results of endovenous laser treatment for primary varicose veins. PATIENTS AND METHOD: From July 2001 to September 2004
Shubnikov de Haas quantum oscillation of the surface states in the metallic Bismuth Telluride sheets
Chen, Taishi; Han, Junhao; Li, Zhaoguo; Song, Fengqi; Zhao, Bo; Wang, Xuefeng; Wang, Baigeng; Wan, Jianguo; Han, Min; Zhang, Rong; Wang, Guanghou
2013-01-01
Metallic Bi2Te3 crystalline sheets with the room-temperature resistivity of above 10 m{\\Omega} cm were prepared and their magnetoresistive transport was measured in a field of up to 9 Tesla. The Shubnikov de Haas oscillations were identified from the secondly-derived magnetoresistance curves. While changing the angle between the field and normal axis of the sheets, we find that the oscillation periods present a cosine dependence on the angle. This indicates a two-dimensional transport due to ...
Unsteady separated boundary layer in a transonic diffuser flow with self-excited oscillations
Hsieh, T.; Coakley, T. J.
1986-01-01
A numerical investigation of two-dimensional unsteady boundary layer in a transonic diffuser flow with self-excited oscillations and strong flow separation by solving the compressible, Reynolds-averaged, thin-layer Navier-Stokes equations with two-equations turbulence model is described. Three different meshes with constant streamwise mesh distribution and varying vertical mesh distribution were used. Results obtained indicate that a refinement of mesh studied here has minimal effect on the mean boundary layer flow but significantly increases the amplitude of oscillation of all flow variables. Comparisons of unsteady wall pressure, velocity profile, terminal shock, and separation pocket among computations and with experiment are presented.
Cardiogenic oscillation induced ventilator autotriggering
Directory of Open Access Journals (Sweden)
Narender Kaloria
2015-01-01
Full Text Available Cardiogenic oscillation during mechanical ventilation can auto-trigger the ventilator resembling patient initiated breadth. This gives a false sense of intact respiratory drive and determination brain death, even if other tests are positive, is not appropriate in such a situation. It will prolong the ICU stay and confound the brain-death determination. In this case report, we describe a 35 year old man who was brought to the hospital after many hours of critical delay following multiple gun shot injuries. The patient suffered a cardiac arrest while on the way from another hospital. After an emergency laparotomy, patient was shifted to Intensive Care Unit (ICU with Glasgow Coma Scale (GCS score of E1VTM1 and was mechanically ventilated. Despite absence of brainstem reflexes, the ventilator continued to be triggered on continuous positive airway pressure (CPAP mode and the patient maintained normal oxygen saturation and acceptable levels of carbon dioxide. An apnoea test confirmed absent respiratory drive. Ventilatory waveform graph analysis, revealed cardiogenic oscillation as the cause for autotrigerring.
Investigation of Transverse Oscillation Method
DEFF Research Database (Denmark)
Udesen, Jesper; Jensen, Jørgen Arendt
2006-01-01
Conventional ultrasound scanners can only display the axial component of the blood velocity vector, which is a significant limitation when vessels nearly parallel to the skin surface are scanned. The transverse oscillation method (TO) overcomes this limitation by introducing a transverse oscillat......Conventional ultrasound scanners can only display the axial component of the blood velocity vector, which is a significant limitation when vessels nearly parallel to the skin surface are scanned. The transverse oscillation method (TO) overcomes this limitation by introducing a transverse...... II. A virtual linear array transducer with center frequency 7 MHz and 128 active elements is created, and a virtual blood vessel of radius 6.4 mm is simulated. The performance of the TO method is found around an initial point in the parameter space. The parameters varied are: flow angle, transmit...... focus depth, receive apodization, pulse length, transverse wave length, number of emissions, signal to noise ratio, and type of echo canceling filter used. Using the experimental scanner RASMUS, the performance of the TO method is evaluated. An experimental flowrig is used to create laminar parabolic...
Waves and oscillations in nature an introduction
Narayanan, A Satya
2015-01-01
Waves and oscillations are found in large scales (galactic) and microscopic scales (neutrino) in nature. Their dynamics and behavior heavily depend on the type of medium through which they propagate.Waves and Oscillations in Nature: An Introduction clearly elucidates the dynamics and behavior of waves and oscillations in various mediums. It presents different types of waves and oscillations that can be observed and studied from macroscopic to microscopic scales. The book provides a thorough introduction for researchers and graduate students in assorted areas of physics, such as fluid dynamics,
High Reliability Oscillators for Terahertz Systems Project
National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...
Introduction to classical and quantum harmonic oscillators
Bloch, Sylvan C
2013-01-01
From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con
Strengthening and damping of synchrotron oscillations
International Nuclear Information System (INIS)
Taratin, A.M.
2001-01-01
Resonance strengthening and damping of synchrotron oscillations of collider bunch halo particles was studied by simulation. It was shown that the strengthening of particle synchrotron oscillations can be highly efficient with using a resonance pulse sequence. The resonance damping of particle synchrotron oscillations is only possible when the inverse population of the accelerated bunch halo is realized. Resonance method of synchrotron oscillation strengthening can be used for the extraction of beam halo particles with a bent crystal to improve the background conditions for colliding beam experiments and to fulfill simultaneously some fixed target experiments
Scleronomic holonomic constraints and conservative nonlinear oscillators
International Nuclear Information System (INIS)
Munoz, R; Gonzalez-Garcia, G; Izquierdo-De La Cruz, E Izquierdo-De La; Fernandez-Anaya, G
2011-01-01
A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present cases in which the effective potential acting on the bead is not analytical around a minimum. The small oscillation approximation cannot be applied to such pathological cases. Nonetheless, these latter instances are studied with other standard techniques.
Scleronomic holonomic constraints and conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Munoz, R; Gonzalez-Garcia, G; Izquierdo-De La Cruz, E Izquierdo-De La [Universidad Autonoma de la Ciudad de Mexico, Centro Historico, Fray Servando Teresa de Mier 92, Col Centro, Del Cuauhtemoc, Mexico DF, CP 06080 (Mexico); Fernandez-Anaya, G, E-mail: rodrigo.munoz@uacm.edu.mx, E-mail: gggharper@gmail.com, E-mail: erickidc@gmail.com, E-mail: guillermo.fernandez@uia.mx [Universidad Iberoamericana, Departamento de Fisica y Matematicas, Prolongacon Paseo de de la Reforma 880, Col Lomas de Santa Fe, Del Alvaro Obregn, Mexico DF, CP 01219 (Mexico)
2011-05-15
A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present cases in which the effective potential acting on the bead is not analytical around a minimum. The small oscillation approximation cannot be applied to such pathological cases. Nonetheless, these latter instances are studied with other standard techniques.
Reentrant transition in coupled noisy oscillators.
Kobayashi, Yasuaki; Kori, Hiroshi
2015-01-01
We report on a synchronization-breaking instability observed in a noisy oscillator unidirectionally coupled to a pacemaker. Using a phase oscillator model, we find that, as the coupling strength is increased, the noisy oscillator lags behind the pacemaker more frequently and the phase slip rate increases, which may not be observed in averaged phase models such as the Kuramoto model. Investigation of the corresponding Fokker-Planck equation enables us to obtain the reentrant transition line between the synchronized state and the phase slip state. We verify our theory using the Brusselator model, suggesting that this reentrant transition can be found in a wide range of limit cycle oscillators.
Oscillating shells and oscillating balls in AdS
Banerjee, Avik; Kundu, Arnab; Roy, Pratik; Virmani, Amitabh
2017-07-01
It has recently been reported that certain thin timelike shells undergo oscillatory motion in AdS. In this paper, we compute two-point function of a probe field in the geodesic approximation in such an oscillating shell background. We confirm that the two-point function exhibits an oscillatory behaviour following the motion of the shell. We show that similar oscillatory dynamics is possible when the perfect fluid on the shell has a polytropic equation of state. Moreover, we show that certain ball like configurations in AdS also exhibit oscillatory motion and comment on how such a solution can be smoothly matched to an appropriate exterior solution. We also demonstrate that the weak energy condition is satisfied for these oscillatory configurations.
Oscillations of Difference Equations with Several Oscillating Coefficients
Directory of Open Access Journals (Sweden)
L. Berezansky
2014-01-01
Full Text Available We study the oscillatory behavior of the solutions of the difference equation Δx(n+∑i=1mpi(nx(τi(n=0,n∈N0[∇xn-∑i=1mpinxσin=0, n∈N] where (pi(n, 1≤i≤m are real sequences with oscillating terms, τi(n[σi(n], 1≤i≤m are general retarded (advanced arguments, and Δ[∇] denotes the forward (backward difference operator Δx(n=x(n+1-x(n[∇x(n=x(n-x(n-1]. Examples illustrating the results are also given.
A coupled-oscillator model of olfactory bulb gamma oscillations.
Directory of Open Access Journals (Sweden)
Guoshi Li
2017-11-01
Full Text Available The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING, best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity.
Qamar, Adnan
2017-06-28
Mass transport and fluid dynamics characteristics in the vicinity of an oscillating cylindrical fiber with an imposed pulsatile inflow condition are computationally investigated in the present study. The work is motivated by a recently proposed design modification to the Total Artificial Lung (TAL) device, which is expected to provide better gas exchange. Navier–Stokes computations, coupled with convection–diffusion equation are performed to assess flow dynamics and mass transport behavior around the oscillating fiber. The oscillations and the pulsatile free stream velocity are represented by two sinusoidal functions. The resulting non-dimensional parameters are Keulegan–Carpenter number (KC), Schmidt number (Sc), Reynolds number (Re), pulsatile inflow amplitude (), and amplitude of cylinder oscillation (). Results are computed for , Sc = 1000, Re = 5 and 10, and 0.7 and 0.25 5.25. The pulsatile inflow parameters correspond to the flow velocities found in human pulmonary artery while matching the operating TAL Reynolds number. Mass transport from the surface of the cylinder to the bulk fluid is found to be primarily dependent on the size of surface vortices created by the movement of the cylinder. Time-averaged surface Sherwood number (Sh) is dependent on the amplitude and KC of cylinder oscillation. Compared to the fixed cylinder case, a significant gain up to 380% in Sh is achieved by oscillating the cylinder even at the small displacement amplitude (AD = 0.75D). Moreover, with decrease in KC the oscillating cylinder exhibits a lower drag amplitude compared with the fixed cylinder case. Inflow pulsation amplitude has minor effects on the mass transport characteristics. However, an increase in results in an increase in the amplitude of the periodic drag force on the cylinder. This rise in the drag amplitude is similar to that measured for the fixed cylinder case. Quantifications of shear stress distribution in the bulk fluid suggest that the physiological
Phenomenology of coupled nonlinear oscillators
Estevez-Rams, E.; Estevez-Moya, D.; Aragón-Fernández, B.
2018-02-01
A recently introduced model of coupled nonlinear oscillators in a ring is revisited in terms of its information processing capabilities. The use of Lempel-Ziv based entropic measures allows to study thoroughly the complex patterns appearing in the system for different values of the control parameters. Such behaviors, resembling cellular automata, have been characterized both spatially and temporally. Information distance is used to study the stability of the system to perturbations in the initial conditions and in the control parameters. The latter is not an issue in cellular automata theory, where the rules form a numerable set, contrary to the continuous nature of the parameter space in the system studied in this contribution. The variation in the density of the digits, as a function of time is also studied. Local transitions in the control parameter space are also discussed.
Optimal oscillation-center transformations
International Nuclear Information System (INIS)
Dewar, R.L.
1984-08-01
A variational principle is proposed for defining that canonical transformation, continuously connected with the identity transformation, which minimizes the residual, coordinate-dependent part of the new Hamiltonian. The principle is based on minimization of the mean-square generalized force. The transformation reduces to the action-angle transformation in that part of the phase space of an integrable system where the orbit topology is that of the unperturbed system, or on primary KAM surfaces. General arguments in favor of this definition are given, based on Galilean invariance, decay of the Fourier spectrum, and its ability to include external fields or inhomogeneous systems. The optimal oscillation-center transformation for the physical pendulum, or particle in a sinusoidal potential, is constructed
Local hysteresis in relaxation oscillators
International Nuclear Information System (INIS)
Alstroem, P.; Christiansen, B.; Levinsen, M.T.
1988-01-01
Relaxation oscillations or 'integrate and fire' phenomena are very commonly found in nature. When modulated by an external force a global hysteresis connected with chaos is often encountered. Besides this kind of hysteresis a local form is found in some systems. We describe briefly the difference and the circumstances under which to observe local hysteresis. A specific system treated in detail is the Fohlmeister model, originally derived to describe a neuronal encoder. In the limit of small damping an analytical solution is obtained. Furthermore, we derive an upper limit to the hysteresis. The results are compared to numerical calculations on the full system and agree quite well. In contrast to e.g. the driven damped pendulum equation the hysteresis is limited in size as compared to the phase-locked region. (orig.)
Oscillating spin-2 dark matter
Marzola, Luca; Raidal, Martti; Urban, Federico R.
2018-01-01
The negative outcomes of laboratory searches, juxtaposed with cosmological observations, may indicate that dark matter has a gravitational origin. We show that coherent oscillations of a massive spin-2 field emerging from bimetric theory can easily account for the observed dark matter abundance. The framework, based on the only known consistent extension of general relativity to interacting spin-2 fields, is testable in precision measurements of the electric charge variation by means of atomic clocks, molecular systems, dedicated resonant mass detectors, as well as gravity interferometers and axionlike-particle experiments. These searches, therefore, provide a new window into the phenomenology of gravity which complements the results of dedicated tests of gravitation. We also present a multimetric extension of the scenario that straightforwardly implements the clockwork mechanism for gravity, explaining the apparent weakness of this force.
Quantum wormholes and harmonic oscillators
Garay, Luis J.
1993-01-01
The quantum state of a wormhole can be represented by a path integral over all asymptotically Euclidean four-geometries and all matter fields which have prescribed values, the arguments of the wave function, on a three-surface which divides the space time manifold into two disconnected parts. Minisuperspace models which consist of a homogeneous massless scalar field coupled to a Friedmann-Robertson-Walker space time are considered. Once the path integral over the lapse function is performed, the requirement that the space time be asymptotically Euclidean can be accomplished by fixing the asymptotic gravitational momentum in the remaining path integral. It is argued that there does not exist any wave function which corresponds to asymptotic field configurations such that the effective gravitational constant is negative in the asymptotic region. Then, the wormhole wave functions can be written as linear combinations of harmonic oscillator wave functions.
Oscillating water column structural model
Energy Technology Data Exchange (ETDEWEB)
Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-09-01
An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.
Oscillating and rotating sine-Gordon system
DEFF Research Database (Denmark)
Olsen, O. H.; Samuelsen, Mogens Rugholm
1986-01-01
The interaction between a 2π kink and the background or vacuum is investigated in the pure sine-Gordon system. For an oscillating background (i.e., the k=0 part of the phonon spectrum) the 2π kink oscillates, while for increasing or decreasing vacuum two phenomena have been observed, depending on...... to a Mathieu equation explaining the excitation....
Phase Multistability in Coupled Oscillator Systems
DEFF Research Database (Denmark)
Mosekilde, Erik; Postnov, D.E.; Sosnovtseva, Olga
2003-01-01
along the orbit of the individual oscillator. Focusing on the mechanisms underlying the appearance of phase multistability, the paper examines a variety of phase-locked patterns. In particular we demonstrate the nested structure of synchronization regions for oscillations with multicrest wave forms...
Synchronization of oscillators in complex networks
Indian Academy of Sciences (India)
https://www.ias.ac.in/article/fulltext/pram/070/06/1175-1198 ... Abstract. Theory of identical or complete synchronization of identical oscillators in arbitrary networks is introduced. ... Combined theories are used to explore and compare three types of semirandom networks for their efficacy in synchronizing oscillators.
Oscillating systems with cointegrated phase processes
DEFF Research Database (Denmark)
Østergaard, Jacob; Rahbek, Anders; Ditlevsen, Susanne
2017-01-01
We present cointegration analysis as a method to infer the network structure of a linearly phase coupled oscillating system. By defining a class of oscillating systems with interacting phases, we derive a data generating process where we can specify the coupling structure of a network that resemb...
Electromagnetic Radiation Originating from Unstable Electron Oscillations
DEFF Research Database (Denmark)
Juul Rasmussen, Jens; Pécseli, Hans
1975-01-01
Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.......Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function....