Quantum oscillations in quasi-two-dimensional conductors

CERN Document Server

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 = ...

What Are Varicose Veins?

Science.gov (United States)

... Leer en español What Is Varicose (VAR-i-kos) veins are swollen, twisted veins that you can ... TA-ze-uhs), spider veins, varicoceles (VAR-i-ko-seals), and other vein problems. Telangiectasias Telangiectasias are ...

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

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)

Qualities of Wigner function and its applications to one-dimensional infinite potential and one-dimensional harmonic oscillator

International Nuclear Information System (INIS)

Xu Hao; Shi Tianjun

2011-01-01

In this article,the qualities of Wigner function and the corresponding stationary perturbation theory are introduced and applied to one-dimensional infinite potential well and one-dimensional harmonic oscillator, and then the particular Wigner function of one-dimensional infinite potential well is specified and a special constriction effect in its pure state Wigner function is discovered, to which,simultaneously, a detailed and reasonable explanation is elaborated from the perspective of uncertainty principle. Ultimately, the amendment of Wigner function and energy of one-dimensional infinite potential well and one-dimensional harmonic oscillator under perturbation are calculated according to stationary phase space perturbation theory. (authors)

Gd-DTPA-enhanced MR venography for varicose veins of the calf

International Nuclear Information System (INIS)

Kohata, Yoshiko; Naito, Akira; Ito, Katuhide.

1995-01-01

2D time-of-flight MR venography (2D TOF MRV) was performed in 16 patients (25 calves) with varicose veins and 2 volunteers (4 calves), and compared with venography. Sequential SPGR (TR/TE/FA=45 ms/7 ms/60deg) transverse images and/or GRASS (TR/TE/FA=100 ms/13 ms/60deg) transverse images were obtained for MRV. Superior presaturation pulse (S-SAT) was placed in 21 calves, and 0.05 mmol/kg Gd-DTPA was used in all calves. Projection MRVs were generated with maximum intensity projection (MIP) reconstruction. Regarding sequence parameter, S-SAT was useful to eliminate signal from artery that would obscure the signal of deep veins. The detectability of deep veins was improved with the use of S-SAT. In the comparison with venography, MRV could more clearly demonstrate varicose veins more than 5 mm in diameter and their drainage veins than venography. But it could not so clearly demonstrate deep veins as venography. It could not detect fine varicose veins less than 5 mm in diameter and connecting veins with valve insufficiency. In the examination of varicose veins, detection of deep veins, large varicose veins and their main drainage veins is clinically important, because diagnosis of patency of deep veins and dilatation of the drainage veins is necessary to choose the treatment, concluding conservative therapy, stripping and sclerotherapy. However, detection of fine varicose veins and connecting veins are not so important because those veins seldom need treatment. MRV was not so suitable for detection of deep veins, but very useful for detection of varicose veins more than 5 mm in diameter and their main drainage veins. In conclusion, MRV is non-invasive and effective method in varicose veins of calf, and it can take the place of venography with the improvement of deep vein detectability. (author)

Chaotic oscillator containing memcapacitor and meminductor and its dimensionality reduction analysis.

Science.gov (United States)

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.

Varicography in the preoperative evaluation of primary varicose veins

International Nuclear Information System (INIS)

Pinzani, A.; Paoli, G.; Gongolo, A.; Spreafico, G.

1989-01-01

Primary varicose veins in the lower limb are usually well evaluated by the surgeon, who avails himself of tornequet tests and Doppler US. However, the operation is often followed by failure or recurrence, or else it requires ugly skin dissection to eradicate an unforeseeably complicated varicose vein. The authors suggest that, whenever the surgeon considers the information obtained with tests and Doppler US inadequate for planning surgery, varicography be performed to get further morphological (and functional) data about the origin of varicose veins, which is of fundamental importance for an accurate surgical planning (crossectomy, stripping, ligation, sclerosis). Out of 100 varicographies consecutively carried out on patients in whom clinical examination was not conclusive, 62% allowed an already planned surgical approach to be changed. The figure rose to 100% in the case of unusual varicose veins. Such a results allowed the needs of both the surgeon (selectivity, effectiveness, radicality) and the patients (narrow scars, absence of relapse) to be respected. Furthermore, it has been pointed out that some vein segments are often only pathological, and they are to be adequately treated, while others can be undamaged, and they are to be preserved for both their function and an eventual by-pass surgery. Varicography is rapidly performed, without complication, and is well accepted by the patients. It is a fundamental help in the preoperative study of primary varicose veins, especially in case of unusual ones, whenever the surgeon is in the slightest diagnostic - and therefore surgical - doubt

Isotropic harmonic oscillator plus inverse quadratic potential in N-dimensional spaces

International Nuclear Information System (INIS)

Oyewumi, K.A.; Bangudu, E.A.

2003-01-01

Some aspects of the N-dimensional isotropic harmonic plus inverse quadratic potential were discussed. The hyperradial equation for isotropic harmonic oscillator plus inverse quadratic potential is solved by transformation into the confluent hypergeometric equation to obtain the normalized hyperradial solution. Together with the hyperangular solutions (hyperspherical harmonics), these form the complete energy eigenfunctions of the N-dimensional isotropic harmonic oscillator plus inverse quadratic potential and the energy eigenvalues are also obtained. These are dimensionally dependent. The dependence of radial solution on the dimensions or potential strength and the degeneracy of the energy levels are discussed. (author)

Oscillator potential for the four-dimensional Hall effect

International Nuclear Information System (INIS)

Mardoyan, Levon; Nersessian, Armen

2005-01-01

We suggest an exactly solvable model of an oscillator on a four-dimensional sphere interacting with an SU(2) Yang monopole. We show that the properties of the model essentially depend on the monopole charge

Epidemiological study on varicose veins in Budapest.

Science.gov (United States)

Bihari, I; Tornoci, L; Bihari, P

2012-03-01

To analyse the prevalence and risk factors of varicose veins and chronic venous disease in Budapest. Data were collected using a questionnaire, as well as by performing physical and Doppler ultrasound examination of 566 adult inhabitants of Budapest and some neighbouring villages. The prevalence of lower-extremity varicose veins was 57.1% in the study population. Verified risk factors include advancing age, pregnancy, jobs requiring a lot of standing, blue-collar work and excess body weight. Neither female gender nor the use of oral contraceptives or hormone replacement therapy was identified as a contributing factor. Hungarian prevalence data and risk factors seem to be similar to other European countries.

The algebra of two dimensional generalized Chebyshev-Koornwinder oscillator

International Nuclear Information System (INIS)

Borzov, V. V.; Damaskinsky, E. V.

2014-01-01

In the previous works of Borzov and Damaskinsky [“Chebyshev-Koornwinder oscillator,” Theor. Math. Phys. 175(3), 765–772 (2013)] and [“Ladder operators for Chebyshev-Koornwinder oscillator,” in Proceedings of the Days on Diffraction, 2013], the authors have defined the oscillator-like system that is associated with the two variable Chebyshev-Koornwinder polynomials. We call this system the generalized Chebyshev-Koornwinder oscillator. In this paper, we study the properties of infinite-dimensional Lie algebra that is analogous to the Heisenberg algebra for the Chebyshev-Koornwinder oscillator. We construct the exact irreducible representation of this algebra in a Hilbert space H of functions that are defined on a region which is bounded by the Steiner hypocycloid. The functions are square-integrable with respect to the orthogonality measure for the Chebyshev-Koornwinder polynomials and these polynomials form an orthonormalized basis in the space H. The generalized oscillator which is studied in the work can be considered as the simplest nontrivial example of multiboson quantum system that is composed of three interacting oscillators

Quantized impedance dealing with the damping behavior of the one-dimensional oscillator

Energy Technology Data Exchange (ETDEWEB)

Zhu, Jinghao; Zhang, Jing; Li, Yuan; Zhang, Yong; Fang, Zhengji; Zhao, Peide, E-mail: pdzhao@eyou.com, E-mail: pdzhao@hebut.edu.cn [School of Science, Hebei University of Technology, Beichen Campus, Tianjin 300401 (China); Li, Erping, E-mail: liep@zju.edu.cn [Institute of High Performance Computing, Fusionopolis, 1 Fusionopolis Way, No. 16-16 Connexis, Singapore 138632 (Singapore)

2015-11-15

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.

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.

Pelvic Vein Embolisation in the Management of Varicose Veins

International Nuclear Information System (INIS)

Ratnam, Lakshmi A.; Marsh, Petra; Holdstock, Judy M.; Harrison, Charmaine S.; Hussain, Fuad F.; Whiteley, Mark S.; Lopez, Anthony

2008-01-01

Pelvic vein incompetence is common in patients with atypical varicose veins, contributing to their recurrence after surgery. Therefore, refluxing pelvic veins should be identified and treated. We present our experience with pelvic vein embolisation in patients presenting with varicose veins. Patients presenting with varicose veins with a duplex-proven contribution from perivulval veins undergo transvaginal duplex sonography (TVUS) to identify refluxing pelvic veins. Those with positive scans undergo embolisation before surgical treatment of their lower limb varicose veins. A total of 218 women (mean age of 46.3 years) were treated. Parity was documented in the first 60 patients, of whom 47 (78.3%) were multiparous, 11 (18.3%) had had one previous pregnancy, and 2 (3.3%) were nulliparous. The left ovarian vein was embolised in 78%, the right internal iliac in 64.7%, the left internal iliac in 56.4%, and the right ovarian vein in 42.2% of patients. At follow-up TVUS, mild reflux only was seen in 16, marked persistent reflux in 6, and new reflux in 3 patients. These 9 women underwent successful repeat embolisation. Two patients experienced pulmonary embolisation of the coils, of whom 1 was asymptomatic and 1 was successfully retrieved; 1 patient had a misplaced coil protruding into the common femoral vein; and 1 patient had perineal thrombophlebitis. The results of our study showed that pelvic venous embolisation by way of a transjugular approach is a safe and effective technique in the treatment of pelvic vein reflux.

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

Prevalence and risk factors of varicose veins among female hairdressers: a cross sectional study in north-east of Iran.

Science.gov (United States)

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.

Poincare' maps of impulsed oscillators and two-dimensional dynamics

International Nuclear Information System (INIS)

Lupini, R.; Lenci, S.; Gardini, L.; Urbino Univ.

1996-01-01

The Poincare' map of one-dimensional linear oscillators subject to periodic, non-linear and time-delayed impulses is shown to reduce to a family of plane maps with possible non-uniqueness of the inverse. By restricting the analysis to a convenient form of the impulse function, a variety of interesting dynamical behaviours in this family are pointed out, including multistability and homoclinic bifurcations. Critical curves of two-dimensional endomorphisms are used to identify the structure of absorbing areas and their bifurcations

Polymorphism of matrix metalloproteinase genes (MMP1 and MMP3) in patients with varicose veins.

Science.gov (United States)

Kurzawski, M; Modrzejewski, A; Pawlik, A; Droździk, M

2009-07-01

Several risk factors for varicose veins have been identified: female gender, combined with obesity and pregnancy, occupations requiring standing for long periods, sedentary lifestyle, history of deep-vein thrombosis and family history. However, no specific gene variants related to a wide prevalence of varicosities in general population have been identified. Extracellular matrix composition, predominantly maintained by matrix metalloproteinases (MMPs), may affect the vein-wall structure, which may lead to dilation of vessels and cause varicosities. MMP-1 (tissue collagenase I) and MMP-3 (stromelysin I) expression was found to be raised in varicose veins compared with normal vessels. Therefore, a study was conducted to evaluate a potential association between MMP1 and MMP3 promoter polymorphisms and a risk of varicose veins. Genotyping for the presence of the polymorphisms -1607dupG (rs1799750) in MMP1 and -1171dupA (rs3025058) in the MMP3 promoter region was performed using PCR and restriction-fragment length polymorphism assays in a group of 109 patients diagnosed with varicose veins and 112 healthy controls. The frequencies of the MMP1 and MMP3 alleles (minor allele frequency 0.440 in patients vs. 0.451 in the controls for MMP1-1607*G and 0.514 vs. 0.469 for MMP3-1171*dupA, respectively) and of genotypes did not differ significantly between patients and controls. The MMP1-1607dupG and MMP3-1171dupA promoter polymorphisms are not valuable markers of susceptibility for varicose veins.

Classical varicose vein surgery in a diverse ethnic community.

Science.gov (United States)

Murli, N L; Navin, I D

2008-08-01

Chronic venous disorders range from telangiactasia or spider veins to varicose veins, venous swellings, skin changes and venous ulcerations. The aim of this study is to assess outcome of varicose vein surgery in the ethnically diverse population of Penang, Malaysia. This study is a retrospective analysis of patients seen from 1999 to 2004. All patients who presented to the outpatient clinic of our surgical department with saphenofemoral junction (SFJ) and/or saphenopopliteal junction (SPJ) reflux associated with incompetence of the great saphenous vein (GSV) or small saphenous vein (SSV) respectively underwent classical varicose varicose vein surgery. A single surgeon at a single institution performed the surgeries. Data from pre-operative, post-operative and follow-up procedures were recorded in case report forms. A total of 202 cases were treated. Of these, 200 were qualified by the inclusion criteria and follow-ups, with 23 who were treated bilaterally. Of those treated, Chinese comprised 47.5%, Indians 27.0%, Malays 12.5% and foreigners 13.0% (largely Indonesian Chinese, British and Americans). The average age was 52.1 years. Indians had the highest average BMI of 29.2, compared to the Chinese who had the lowest of 24.6. Based on occupation, housewives (43.0%), blue collar workers (19.0%), salespersons (12.0%) and factory workers (9.5%) were among those afflicted with varicose veins. While local Chinese predominated in the business groups (salespersons and food-related workers), the Indians and Malays in this study were mainly factory workers and/or blue collar workers. Symptomatology in descending order of severity included pain in 80.0% of cases, swelling in 65.5%, heaviness in 53.5%, cramps in 53.0%, lipodermatosclerosis in 39.0%, superficial thrombophlebitis in 33.5%, venous ulceration in 32.0%, eczema 22.0% and cellulitis in 12.5% of patients. Post surgery pains dropped to 9.9%, cramps 6.4%, heaviness 5.5% and swelling 5.3% (p<0.0001 in all groups

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.

Global search demand for varicose vein information on the internet.

Science.gov (United States)

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 demand significantly increased in the northern hemisphere (p demand compared to cooler winter months (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.

[Health education for varicose ulcer patients through group activities].

Science.gov (United States)

da Silva, Jodo Luis Almeida; Lopes, Marta Julia Marques

2006-06-01

It is a report on the group activities carried out with carriers of varicose ulcer in a health unit in Porto Alegre, Rio Grande do Sul, Brazil. The varicose ulcer presents factors, besides the biological ones, which interfere in the cicatrization, in the relapse cases and in its effective resolution. The proposed activities aimed at producing behavior changes with the intention of achieving self-care, providing information, socializing the participants, and stimulating cooperation, searching for joint solutions, aggregating interdisciplinary spirit and improving the care. Two groups have been formed and a thematic schedule established. The results have showed higher adhesion to the treatment, behavioral changes, and adapted and more effective attitudes of the health team.

Self-organization and oscillation of negatively charged dust particles in a 2-dimensional dusty plasma

Energy Technology Data Exchange (ETDEWEB)

Song, Y.L. [College of Science, China Agricultural University, Beijing 100083 (China); Huang, F., E-mail: huangfeng@cau.edu.cn [College of Science, China Agricultural University, Beijing 100083 (China); Chen, Z.Y., E-mail: chenzy@mail.buct.edu.cn [Department of Physics, Beijing University of Chemical Technology, Beijing 100029 (China); State Key Laboratory of Laser Propulsion & Application, Beijing 101416 (China); Liu, Y.H. [School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025 (China); Yu, M.Y. [Institute for Fusion Theory and Simulation, Zhejiang University, Hangzhou 310027 (China); Institute for Theoretical Physics I, Ruhr University, D-44801 Bochum (Germany)

2016-02-22

Negatively charged dust particles immersed in 2-dimensional dusty plasma system are investigated by molecular dynamics simulations. The effects of the confinement potential and attraction interaction potential on dust particle self-organization are studied in detail and two typical dust particle distributions are obtained when the system reaches equilibrium. The average radial velocity (ARV), average radial force (ARF) and radial mean square displacement are employed to analyze the dust particles' dynamics. Both ARVs and ARFs exhibit oscillation behaviors when the simulation system reaches equilibrium state. The relationships between the oscillation and confinement potential and attraction potential are studied in this paper. The simulation results are qualitatively similar to experimental results. - Highlights: • Self-organization and oscillation of a 2-dimensional dusty plasma is investigated. • Effect of the confinement potential on dust self-organization and oscillation is given. • Effect of the attraction potential on dust self-organization and oscillation is studied.

Self-organization and oscillation of negatively charged dust particles in a 2-dimensional dusty plasma

International Nuclear Information System (INIS)

Song, Y.L.; Huang, F.; Chen, Z.Y.; Liu, Y.H.; Yu, M.Y.

2016-01-01

Negatively charged dust particles immersed in 2-dimensional dusty plasma system are investigated by molecular dynamics simulations. The effects of the confinement potential and attraction interaction potential on dust particle self-organization are studied in detail and two typical dust particle distributions are obtained when the system reaches equilibrium. The average radial velocity (ARV), average radial force (ARF) and radial mean square displacement are employed to analyze the dust particles' dynamics. Both ARVs and ARFs exhibit oscillation behaviors when the simulation system reaches equilibrium state. The relationships between the oscillation and confinement potential and attraction potential are studied in this paper. The simulation results are qualitatively similar to experimental results. - Highlights: • Self-organization and oscillation of a 2-dimensional dusty plasma is investigated. • Effect of the confinement potential on dust self-organization and oscillation is given. • Effect of the attraction potential on dust self-organization and oscillation is studied.

Three-dimensional features on oscillating microbubbles streaming flows

Science.gov (United States)

Rossi, Massimiliano; Marin, Alvaro G.; Wang, Cheng; Hilgenfeldt, Sascha; Kähler, Christian J.

2013-11-01

Ultrasound-driven oscillating micro-bubbles have been used as active actuators in microfluidic devices to perform manifold tasks such as mixing, sorting and manipulation of microparticles. A common configuration consists in side-bubbles, created by trapping air pockets in blind channels perpendicular to the main channel direction. This configuration results in bubbles with a semi-cylindrical shape that creates a streaming flow generally considered quasi two-dimensional. However, recent experiments performed with three-dimensional velocimetry methods have shown how microparticles can present significant three-dimensional trajectories, especially in regions close to the bubble interface. Several reasons will be discussed such as boundary effects of the bottom/top wall, deformation of the bubble interface leading to more complex vibrational modes, or bubble-particle interactions. In the present investigation, precise measurements of particle trajectories close to the bubble interface will be performed by means of 3D Astigmatic Particle Tracking Velocimetry. The results will allow us to characterize quantitatively the three-dimensional features of the streaming flow and to estimate its implications in practical applications as particle trapping, sorting or mixing.

A new look at the harmonic oscillator problem in a finite-dimensional Hilbert space

International Nuclear Information System (INIS)

Bagchi, B.

1995-01-01

In this Letter some basic properties of a truncated oscillator are studied. By using finite-dimensional representation matrices of the truncated oscillator we construct new parasupersymmetric schemes and remark on their relevance to the transition operators of the non-interacting N-level system endowed with bosonic modes. ((orig.))

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.

HFE p.C282Y gene variant is associated with varicose veins in Russian population.

Science.gov (United States)

Sokolova, Ekaterina A; Shadrina, Alexandra S; Sevost'ianova, Kseniya S; Shevela, Andrey I; Soldatsky, Evgenii Yu; Seliverstov, Evgenii I; Demekhova, Marina Yu; Shonov, Oleg A; Ilyukhin, Evgenii A; Smetanina, Mariya A; Voronina, Elena N; Zolotukhin, Igor A; Filipenko, Maxim L

2016-08-01

Recently, the association of polymorphism rs1800562 (p.C282Y) in the hemochromatosis (HFE) gene with the increased risk of venous ulceration was shown. We hypothesized that HFE gene polymorphism might be involved not only in ulceration process, but also in susceptibility to primary varicose veins. We genotyped HFE p.C282Y (rs1800562) and p.H63D (rs1799945) variants in patients with primary varicose veins (n = 463) and in the control group (n = 754). In our study, p.282Y variant (rs1800562 A allele) was significantly associated with the risk of varicose veins (OR 1.79, 95 % CI = 1.11-2.89, P = 0.02). A borderline significant reverse association of p.63D variant (rs1799945 G allele) with venous leg ulcer development was revealed in Russians (OR 0.25, 95 % CI = 0.06-1.00, P = 0.05), but not in the meta-analysis (P = 0.56). We conclude that the HFE gene polymorphism can affect the risk of developing primary varicose veins.

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

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

Complications of Sclerotherapy with Sclerosing Foam in Lower Extremity Varicose Veins

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Hossein Hemmati

2015-01-01

Full Text Available Background: Using sclerotherapy with foam has caused a great change in treatment of varicose veins. Although, it is more than a century that it is being used, no exact and comprehensive knowledge of its complications has been published yet with regard to the existing facilities in Iran. Materials and Methods: In this cross-sectional study, Patients with varicose veins of lower extremity referred to cardiology clinic of Razi hospital, Rasht were included in the study after doppler sonography and in case of presence of varicose veins with more than 2 mm diameter in lower extremities without inadequacy of saphenofemoral and saphenopopliteal valve. They then underwent sclerosing with foam treatment. The total number of patients was 156 who were examined 2 weeks and 3 months after sclerotherapy in terms of complications such as pain, pigmentation, recurrence, phlebitis, deep vein thrombosis and skin necrosis. Results: Out of 156 patients, 47 were men and 109 women whose mean±SD age was 46.5±12.2 years. Two weeks after sclerotherapy, pain in 95 patients (65.1%, pigmentation in 79 patients (53.4%, recurrence in 5 patients (3.4%, necrosis in 8 patients (5.5% and no phlebitis was witnessed. Three months after sclerotherapy, pain in 10 patients (6.8%, pigmentation in 52 patients (35.1%, recurrence in 13 patients (8.8% and phlebitis in 13 patients (8.8% were seen; however, necrosis was not observed Conclusion: Sclerotherapy with foam is an effective, safe and inexpensive method for treatment of varicose veins of lower extremities. Thus, in case of a careful selection of patients and conduction in an equipped center, few complications will be seen.

Clinical effectiveness of DSA-guided foam sclerotherapy for varicose veins of lower limbs

International Nuclear Information System (INIS)

Fu Jianhua; He Xu; Chen Guoping; Gu Jianping; Wang Yafei

2011-01-01

Objective: To investigate the clinical effect of DSA-guided foam sclerotherapy for varicose veins of lower limbs. Methods: A total of 25 diseased limbs in 20 patients with varicose veins were treated with foam sclerotherapy. The patients were followed up for six months. Sodium morrhuate, used as the sclerosant, was foamed with air by using Tessari's method, with liquid-gas ratio of 1 : 4. The clinical effectiveness was estimated by CEAP, clinical signs and symptoms. Results: A total of 25 limbs in 20 patients with varicose veins were successfully treated with foam sclerotherapy. The technical success rate was 100%. No serious complications such as pulmonary embolism occurred. Phlebitis was observed in two cases at 2 days 4 days after foam sclerotherapy respectively which was relieved after anti-inflammatory medication for 3 days. At the time of discharge, excellent result was seen in 12 (48%) limbs, good effect in 13 (52%) limbs. The total effective rate was 100%. Six months after the treatment, excellent effect was obtained in 15 (60%) limbs and good effect was seen in 10 (40%) limbs. The total effective rate was 100%. Conclusion: DSA-guided foam sclerotherapy is a safe, effective and micro-invasive treatment for varicose veins of lower limbs with high technical success rate, although the long-term clinical effect needs to be further evaluated. (authors)

The Study of Two-Dimensional Oscillations Using a Smartphone Acceleration Sensor: Example of Lissajous Curves

Science.gov (United States)

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…

The clinical efficacy observation of fluoroscopy-guided foam sclerotherapy with lauromacrogol for varicose veins of the lower extremities

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

Simplest simulation model for three-dimensional xenon oscillations in large PWRs

International Nuclear Information System (INIS)

Shimazu, Yoichiro

2004-01-01

Xenon oscillations in large PWRs are well understood and there have been no operational problems remained. However, in order to suppress the oscillations effectively, optimal control strategy is preferable. Generally speaking in such optimality search based on the modern control theory, a large volume of transient core analyses is required. For example, three dimensional core calculations are inevitable for the analyses of radial oscillations. From this point of view, a very simple 3-D model is proposed, which is based on a reactor model of only four points. As in the actual reactor operation, the magnitude of xenon oscillations should be limited from the view point of safety, the model further assumes that the neutron leakage can be also small or even constant. It can explicitly use reactor parameters such as reactivity coefficients and control rod worth directly. The model is so simplified as described above that it can predict oscillation behavior in a very short calculation time even on a PC. However the prediction result is good. The validity of the model in comparison with measured data and the applications are discussed. (author)

Spin–orbit coupling induced magnetoresistance oscillation in a dc biased two-dimensional electron system

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)

Patients and physicians agree only partially in symptoms and clinical findings before and after treatment for varicose veins

DEFF Research Database (Denmark)

Klitfod, Lotte; Sillesen, Henrik; Jensen, Leif Panduro

2018-01-01

findings. Methods In the period January-March 2011, 379 legs in 287 patients treated for varicose veins were registered in the Danish Clinical Vein Database and compared to the Aberdeen Varicose Vein Questionnaire. Results Patients and physicians agreed in reduction of symptoms after intervention with one...... 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 

Know your market: use of online query tools to quantify trends in patient information-seeking behavior for varicose vein treatment.

Science.gov (United States)

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.

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)

Clinical course and effective treatment of varicose vein of lower limb in diabetic patients

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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.

The clinical efficacy evaluation of transcatheter hardening treatment for varicose veins of lower extremity

International Nuclear Information System (INIS)

Chen Junhui; Ren Yi; He Ping; Xiong Hongli; Wang Li; Zhou Xianbo

2007-01-01

Objective: To explore the clinical efficacy and safety of transcatheter absolute ethanol injection treatment on varicose veins of lower extremity. Methods: twenty-there patients with 25 varicose veins of lower extremity were treated by puncture of great saphenous vein above 1-2 cm of complicated inner ankle, perforating catheter to the point below the 3-4 cm of the conjunction of great saphenous vein and Femoral vein and pressing the conjunction of these two veins. Under the monitor of DSA, inject the absolute ethanol slowly while retrieve the catheter little by little (one limb with varicose veins injected total volume 15-20 mi), in the mean time, using contrast agent to monitor the level of embolism until the formation of total embolism in the all great saphenous veins. Results: All the cases were retrospectively followed up with CDFI examination after 3-12 months of the surgery, No blood flow were seen in the 25 embolismic great saphenous vein. Clinical symptom were alleviated obviously after 2-3 weeks of treatment; varicose veins were collapse after 3 to 7 days. Two cases of leg ulceration were healed after 4 to 6 weeks of operation. 20 limbs were found mild swelling in the 2 day after the surgery. However, all the cases were disappeared after 1 to 2 weeks; 4 treated limbs developed delayed paresthesia in the 3 day after the surgery, and recovered totally in the 2 weeks. No complications of deep vein thrombosis, lung thrombosis etc al, were found after operation. Conclusions: Using transcatheter injection of absolute ethanol to treat varicose veins of lower extremity has the advantage of less invasion, more safety and low appearance of complications. The short term efficacy is solid while the long term effect needs further evaluation. (authors)

Simulation, Fabrication and Analysis of Silver Based Ascending Sinusoidal Microchannel (ASMC for Implant of Varicose Veins

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Muhammad Javaid Afzal

2017-09-01

Full Text Available Bioengineered veins can benefit humans needing bypass surgery, dialysis, and now, in the treatment of varicose veins. The implant of this vein in varicose veins has significant advantages over the conventional treatment methods. Deep vein thrombosis (DVT, vein patch repair, pulmonary embolus, and tissue-damaging problems can be solved with this implant. Here, the authors have proposed biomedical microdevices as an alternative for varicose veins. MATLAB and ANSYS Fluent have been used for simulations of blood flow for bioengineered veins. The silver based microchannel has been fabricated by using a micromachining process. The dimensions of the silver substrates are 51 mm, 25 mm, and 1.1 mm, in length, width, and depth respectively. The dimensions of microchannels grooved in the substrates are 0.9 mm in width and depth. The boundary conditions for pressure and velocity were considered, from 1.0 kPa to 1.50 kPa, and 0.02 m/s to 0.07 m/s, respectively. These are the actual values of pressure and velocity in varicose veins. The flow rate of 5.843 (0.1 nL/s and velocity of 5.843 cm/s were determined at Reynolds number 164.88 in experimental testing. The graphs and results from simulations and experiments are in close agreement. These microchannels can be inserted into varicose veins as a replacement to maintain the excellent blood flow in human legs.

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)

The sapheno femoral junction involvement in the treatment of varicose veins disease

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Stefano Ricci

2017-07-01

Full Text Available Sapheno femoral junction (SFJ incompetence has been considered the most important cause of chronic venous insufficiency in a high percent of cases since the beginning of history varicose veins treatment. As a consequence SFJ dissection, ligation and section has been practiced all along the last century, generally associated to great saphenous vein stripping, with the porpoise of stopping the effect of hydrostatic pressure considered the origin of varicose veins. Recurrence prevalence at the site of SFJ, even in correctly performed dissection suggests that this attitude may not be the ideal one. Moreover, with the introduction of catheter-based systems of endovenous heating of the great saphenous vein with radiofrequency or endovenous laser ablation, it was shown that venous ablation could be achieved without high ligation of the SFJ. Also foam sclerotherapy demonstrated good results, even if less effective, always leaving the SFJ untouched. Following this trend several methods have been suggested that spare the SFJ, so that this site have lost its strategical importance. In this review history of the SFJ involvement in the varicose vein strategy is analyzed with particular attention to the new generation methods, technology assisted, launched on the market.

Varicose vein disease in children with klippel-trenaunay syndrome

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Yu.O. Syniachenko

2017-02-01

Full Text Available The article presents a review of the literature, which describes the clinical picture and diagnosis of varicose vein disease in Klippel-Trenaunay syndrome, methods of treatment with intravenous and transcutaneous laser coagulation, endovenous radioablation, foam sclerotherapy of vessels and venectomy. There are underlined genetic defects in the genesis of the disease, the role of pro-inflammatory and immunoregulatory imbalance of cytokines, growth factors, cell adhesion molecules, matrix metalloproteinases etс. in pathogenic constructions of venous damage. This congenital vascular patho­logy is not as rare as it is commonly thought, and the patients suffering from this pathology since childhood are often being unsuccessfully treated in adulthood for varicose veins, elephantiasis and recurrent phlebothrombosis, when diagnosis of Klippel-Trenaunay syndrome have never previously established. This literature review has to attract the attention to the problem under discussion not only of pediatricians, but also of therapeutists and vascular surgeons-phlebologists.

Coupled Langmuir oscillations in 2-dimensional quantum plasmas

International Nuclear Information System (INIS)

Akbari-Moghanjoughi, M.

2014-01-01

In this work, we present a hydrodynamic model to study the coupled quantum electron plasma oscillations (QEPO) for two dimensional (2D) degenerate plasmas, which incorporates all the essential quantum ingredients such as the statistical degeneracy pressure, electron-exchange, and electron quantum diffraction effect. Effects of diverse physical aspects like the electronic band-dispersion effect, the electron exchange-correlations and the quantum Bohm-potential as well as other important plasma parameters such as the coupling parameter (plasma separation) and the plasma electron number-densities on the linear response of the coupled system are investigated. By studying three different 2D plasma coupling types, namely, graphene-graphene, graphene-metalfilm, and metalfilm-metalfilm coupling configurations, it is remarked that the collective quantum effects can influence the coupled modes quite differently, depending on the type of the plasma configuration. It is also found that the slow and fast QEPO frequency modes respond very differently to the change in plasma parameters. Current findings can help in understanding of the coupled density oscillations in multilayer graphene, graphene-based heterojunctions, or nanofabricated integrated circuits

Adoption of endovenous laser treatment as the primary treatment modality for varicose veins: the Auckland City Hospital experience.

Science.gov (United States)

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.

Clinical presentation of women with pelvic source varicose veins in the perineum as a first step in the development of a disease-specific patient assessment tool.

Science.gov (United States)

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

Solution of Schrodinger equation for Three Dimensional Harmonics Oscillator plus Rosen-Morse Non-central potential using NU Method and Romanovski Polynomials

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

Long-term memory in Aplysia modulates the total number of varicosities of single identified sensory neurons.

OpenAIRE

Bailey, C H; Chen, M

1988-01-01

The morphological consequences of long-term habituation and sensitization of the gill withdrawal reflex in Aplysia california were explored by examining the total number of presynaptic varicosities of single identified sensory neurons (a critical site of plasticity for the biochemical and biophysical changes that underlie both types of learning) in control and behaviorally trained animals. Sensory neurons from habituated animals had 35% fewer synaptic varicosities than did sensory neurons fro...

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./.

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./

The effect of the dust’s electric dipole moment on transverse oscillations of the one dimensional dusty crystals

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S Karimi

2013-10-01

Full Text Available In this paper, we investigated the effect of dipole-dipole interaction between the dust particles on the transverse oscillation of one dimensional dusty crystal. We used the Boltzmann distribution for the electrons and ions density and assumed that dust particles are negatively charged. The equation of motion for dust particles in this one dimensional chain was obtained. It is shown that the direction of dipoles plays an important role in the motion of dusts and significantly changes the oscillation frequency. Also, in the long wavelength approximation, a nonlinear Schrödinger equation for the evolution of the amplitude of the nonlinear oscillations was derived, showing that both the bright solitons and the dark solitons could exist.

EVALUATION OF “SEPS” PROCEDURE IN THE MANAGEMENT OF PRIMARY VARICOSE VEINS WITH INCOMPETENT LOWER LIMB PERFORATOR

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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

Conventional operation and laser therapy in the treatment of varicose veins

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

Objective: To evaluate the effectiveness of endovenous laser therapy and conventional therapy on the varicose of great saphenous vein. Methods: Thirty-two patients received endovenous laser therapy and 32 patients were operated by conventional therapy (high ligation and stripping). The observation results of great saphenous vein(GSV) were recorded by clinical evaluation and duplex ultrasound examination. And the operating time, intraoperative blood loss, time to become moveable, duration of hospitalization and degree of feeling pain were compared between the two groups. Results: Compared with conventional therapy, laser therapy had good curative effect with less complications and no scars and no pains. There were significant differences between the two groups (P＜0.01). Conclusion: Laser therapy for varicose of great saphenous vein is better than the conventional therapy. It deserves to be widely used in clinical treatment.

Clinical results of a new strategy (modified CHIVA) for surgical treatment of anterior accessory great saphenous varicose veins.

Science.gov (United States)

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.

Two new types of solvability of the one-dimensional anharmonic oscillators

International Nuclear Information System (INIS)

Znojil, M.

1989-01-01

In the Schroedinger picture, we propose a new modification of the so-called Hill-determinant technique. It is shown to guarantee a proper matching of the two underlying power series Ψ(x) at x=0. In the Heisenberg picture, an evolution of the same one-dimensional polynomially anharmonic oscillator is considered. A modified Peano-Baker method is applied and shown to define the explicit solutions by recurrences. 11 refs

Case report: Varicosity of the communicating vein between the left renal vein and the left ascending lumbar vein mimicking a renal artery aneurysm: Report of an unusual site of varicose veins and a novel hypothesis to explain its association with abdominal pain

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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.

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

Prognosis of complicated clinical course of varicose veins of lower extremities on the basis of analysis of phenotypic characteristics of connective tissue dysplasia

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.

Self-oscillations of a two-dimensional shear flow with forcing and dissipation

Science.gov (United States)

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 limited to develop only one vortical instability by choosing an appropriate width of the forcing band. The most 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.

[Interrelationship between lower limb varicosity, the grade of connective tissue dysplasia and atrial fibrillation in patients with coronary artery disease].

Science.gov (United States)

Forster, O V; Tsarev, O A; Shvarts, Iu G

2006-01-01

To determine interrelationship between lower limb varicosity, the clinical grade of non-differentiated dysplasia of the connective tissue and atrial fibrillation in patients with coronary artery disease (CAD). Altogether 156 coronary patients were examined. Persistent atrial fibrillation was present in 58 and chronic in 38 patients. The reference group comprised 60 patients without evident rhythm disorders in persons suffering from CAD. Markers of connective tissue dysplasia () were revealed on the part of the skeleton, joints skin and visceral organs. Lower limb varicosity was recorded as well. The number of the stigmas in the study groups was different. So, in the patient group without rhythm disorders, the mean number of the stigmas was equal to 3, which is a variant of normal. In the groups with persistent and constant AF, this indicator was equal to 4.7 and 5.2 respectively (patrial fibrilation there is a direct close correlation between the signs of connective tissue dysplasia and lower limb varicosity. In patients with persistent AF lower limb varicosity occurs more frequently than in CAD patients with normal rhythm.

Dynamical Symmetries of Two-Dimensional Dirac Equation with Screened Coulomb and Isotropic Harmonic Oscillator Potentials

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)

A one-dimensional model illustrating virtual-cathode formation in a novel coaxial virtual-cathode oscillator.

CSIR Research Space (South Africa)

Turner, GR

2014-09-01

Full Text Available A one-dimensional electrostatic sheet model of a coaxial geometry Virtual Cathode Oscillator (VCO) is presented. The cathode is centrally located and connects to a peripherally located plate electrode to form a resonant cavity, and is thus...

A randomized trial comparing treatments for varicose veins.

Science.gov (United States)

Brittenden, Julie; Cotton, Seonaidh C; Elders, Andrew; Ramsay, Craig R; Norrie, John; Burr, Jennifer; Campbell, Bruce; Bachoo, Paul; Chetter, Ian; Gough, Michael; Earnshaw, Jonothan; Lees, Tim; Scott, Julian; Baker, Sara A; Francis, Jill; Tassie, Emma; Scotland, Graham; Wileman, Samantha; Campbell, Marion K

2014-09-25

Ultrasound-guided foam sclerotherapy and endovenous laser ablation are widely used alternatives to surgery for the treatment of varicose veins, but their comparative effectiveness and safety remain uncertain. In a randomized trial involving 798 participants with primary varicose veins at 11 centers in the United Kingdom, we compared the outcomes of foam, laser, and surgical treatments. Primary outcomes at 6 months were disease-specific quality of life and generic quality of life, as measured on several scales. Secondary outcomes included complications and measures of clinical success. After adjustment for baseline scores and other covariates, the mean disease-specific quality of life was slightly worse after treatment with foam than after surgery (P=0.006) but was similar in the laser and surgery groups. There were no significant differences between the surgery group and the foam or the laser group in measures of generic quality of life. The frequency of procedural complications was similar in the foam group (6%) and the surgery group (7%) but was lower in the laser group (1%) than in the surgery group (Pdisease-specific quality of life in the foam group than in the surgery group. All treatments had similar clinical efficacy, but complications were less frequent after laser treatment and ablation rates were lower after foam treatment. (Funded by the Health Technology Assessment Programme of the National Institute for Health Research; Current Controlled Trials number, ISRCTN51995477.).

Two-dimensional collective electron magnetotransport, oscillations, and chaos in a semiconductor superlattice.

Science.gov (United States)

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.

Two-dimensional collective electron magnetotransport, oscillations, and chaos in a semiconductor superlattice

Science.gov (United States)

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.

Endovascular Radiofrequency Ablation for Varicose Veins

Science.gov (United States)

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

Spatially structured oscillations in a two-dimensional excitatory neuronal network with synaptic depression

KAUST Repository

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.

Spatially structured oscillations in a two-dimensional excitatory neuronal network with synaptic depression

KAUST Repository

Kilpatrick, Zachary P.; Bressloff, Paul C.

2009-01-01

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.

Flipping-shuttle oscillations of bright one- and two-dimensional solitons in spin-orbit-coupled Bose-Einstein condensates with Rabi mixing

Science.gov (United States)

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.

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.

Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins : Heat transfer and boiling in endovenous laser ablation of varicose veins

NARCIS (Netherlands)

de Boer, A.; Oliveira, J.L.G.; van der Geld, C.W.M.; Malskat, Wendy S.J.; van den Bos, Renate; Nijsten, Tamar; van Gemert, M.J.C.

2017-01-01

Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in

Anisotropic Friedel oscillations in a two-dimensional electron gas with a Rashba-Dresselhaus spin-orbit interaction

Science.gov (United States)

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.

3D Oscillator and Coulomb Systems reduced from Kahler spaces

OpenAIRE

Nersessian, Armen; Yeranyan, Armen

2003-01-01

We define the oscillator and Coulomb systems on four-dimensional spaces with U(2)-invariant Kahler metric and perform their Hamiltonian reduction to the three-dimensional oscillator and Coulomb systems specified by the presence of Dirac monopoles. We find the Kahler spaces with conic singularity, where the oscillator and Coulomb systems on three-dimensional sphere and two-sheet hyperboloid are originated. Then we construct the superintegrable oscillator system on three-dimensional sphere and ...

A model of the two-dimensional quantum harmonic oscillator in an AdS{sub 3} background

Energy Technology Data Exchange (ETDEWEB)

Frick, R. [Universitaet zu Koeln, Institut fuer Theoretische Physik, Cologne (Germany)

2016-10-15

In this paper we study a model of the two-dimensional quantum harmonic oscillator in a three-dimensional anti-de Sitter background. We use a generalized Schroedinger picture in which the analogs of the Schroedinger operators of the particle are independent of both the time and the space coordinates in different representations. The spacetime independent operators of the particle induce the Lie algebra of Killing vector fields of the AdS{sub 3} spacetime. In this picture, we have a metamorphosis of the Heisenberg uncertainty relations. (orig.)

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...... and a preventive potential of more than 60% of all cases in exposed occupations....

Dimensional oscillation. A fast variation of energy embedding gives good results with the AMBER potential energy function.

Science.gov (United States)

Snow, M E; Crippen, G M

1991-08-01

The structure of the AMBER potential energy surface of the cyclic tetrapeptide cyclotetrasarcosyl is analyzed as a function of the dimensionality of coordinate space. It is found that the number of local energy minima decreases as the dimensionality of the space increases until some limit at which point equipotential subspaces appear. The applicability of energy embedding methods to finding global energy minima in this type of energy-conformation space is explored. Dimensional oscillation, a computationally fast variant of energy embedding is introduced and found to sample conformation space widely and to do a good job of finding global and near-global energy minima.

One dimension harmonic oscillator

International Nuclear Information System (INIS)

Cohen-Tannoudji, Claude; Diu, Bernard; Laloe, Franck.

1977-01-01

The importance of harmonic oscillator in classical and quantum physics, eigenvalues and eigenstates of hamiltonian operator are discussed. In complement are presented: study of some physical examples of harmonic oscillators; study of stationnary states in the /x> representation; Hermite polynomials; resolution of eigenvalue equation of harmonic oscillator by polynomial method; isotope harmonic oscillator with three dimensions; charged harmonic oscillator in uniform electric field; quasi classical coherent states of harmonic oscillator; eigenmodes of vibration of two coupled harmonic oscillators; vibration modus of a continuous physical system (application to radiation: photons); vibration modus of indefinite linear chain of coupled harmonic oscillators (phonons); one-dimensional harmonic oscillator in thermodynamic equilibrium at temperature T [fr

A one-dimensional model of the semiannual oscillation driven by convectively forced gravity waves

Science.gov (United States)

Sassi, Fabrizio; Garcia, Rolando R.

1994-01-01

A one-dimensional model that solves the time-dependent equations for the zonal mean wind and a wave of specified zonal wavenumber has been used to illustrate the ability of gravity waves forced by time-dependent tropospheric heating to produce a semiannual oscillation (SAO) in the middle atmosphere. When the heating has a strong diurnal cycle, as observed over tropical landmasses, gravity waves with zonal wavelengths of a few thousand kilometers and phase velocities in the range +/- 40-50 m/sec are excited efficiently by the maximum vertical projection criterion (vertical wavelength approximately equals 2 x forcing depth). Calculations show that these waves can account for large zonal mean wind accelerations in the middle atmosphere, resulting in realistic stratopause and mesopause oscillations. Calculations of the temporal evolution of a quasi-conserved tracer indicate strong down-welling in the upper stratosphere near the equinoxes, which is associated with the descent of the SAO westerlies. In the upper mesosphere, there is a semiannual oscillation in tracer mixing ratio driven by seasonal variability in eddy mixing, which increases at the solstices and decreases at the equinoxes.

Can interposition of a silicone implant after sapheno-femoral ligation prevent recurrent varicose veins?

NARCIS (Netherlands)

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

Hall field-induced magnetoresistance oscillations of a two-dimensional electron system

International Nuclear Information System (INIS)

Kunold, A.; Torres, M.

2008-01-01

We develop a model of the nonlinear response to a dc electrical current of a two-dimensional electron system (2DES) placed on a magnetic field. Based on the exact solution to the Schroedinger equation in arbitrarily strong electric and magnetic fields, and separating the relative and guiding center coordinates, a Kubo-like formula for the current is worked out as a response to the impurity scattering. Self-consistent expressions determine the longitudinal and Hall components of the electric field in terms of the dc current. The differential resistivity displays strong Hall field-induced oscillations, in agreement with the main features of the phenomenon observed in recent experiments

The psychological aspects of everyday functioning in a group of patients with varicose veins – an assessment with VEINES Qol/Sym for patients before and after varicose veins surgery

Directory of Open Access Journals (Sweden)

Łukasz Migdalski

2015-10-01

Full Text Available Psychological functioning of patients in early stages of venous insufficiency has not been a common subject of scientific investigation so far, even though this group of patients experiences many limitations in daily functioning, as well as psychological distress. Varicose veins are the most common type of venous insufficiency, with an epidemiology of up to 50% of the western population. The present study is concerned with the functioning of a group undergoing surgery of varicose veins. The operation was carried out in an ambulatory mode, and such psychological factors as acceptance of illness, anxiety–state, anxiety–trait, and wellbeing (treated as personality construct have been considered. It is the first time that such variables have been used with the new tool for assessing quality of life in venous diseases (VEINES Qol/Sym, and no previous findings about applying VEINES Qol/Sym to assess patients after varicose veins operations exist. The results are promising, especially for combining such psychological variables as anxiety, acceptance of illness, or wellbeing with specific venous measures of quality of life. It has been proved that there is a need for monitoring psychological variables in the group of patients in an early stage of chronic venous illness. Further research on other venous patient groups is necessary to fully understand the specificity of these groups.

Three-dimensional chimera patterns in networks of spiking neuron oscillators

Science.gov (United States)

Kasimatis, T.; Hizanidis, J.; Provata, A.

2018-05-01

We study the stable spatiotemporal patterns that arise in a three-dimensional (3D) network of neuron oscillators, whose dynamics is described by the leaky integrate-and-fire (LIF) model. More specifically, we investigate the form of the chimera states induced by a 3D coupling matrix with nonlocal topology. The observed patterns are in many cases direct generalizations of the corresponding two-dimensional (2D) patterns, e.g., spheres, layers, and cylinder grids. We also find cylindrical and "cross-layered" chimeras that do not have an equivalent in 2D systems. Quantitative measures are calculated, such as the ratio of synchronized and unsynchronized neurons as a function of the coupling range, the mean phase velocities, and the distribution of neurons in mean phase velocities. Based on these measures, the chimeras are categorized in two families. The first family of patterns is observed for weaker coupling and exhibits higher mean phase velocities for the unsynchronized areas of the network. The opposite holds for the second family, where the unsynchronized areas have lower mean phase velocities. The various measures demonstrate discontinuities, indicating criticality as the parameters cross from the first family of patterns to the second.

Large Vaginal Varicosities in the Setting of Pregnancy without Known Hepatic or Vascular Risks: A Case Report and Review of the Literature.

Science.gov (United States)

Sueyoshi, Mark; Clevenger, Steven; Hart, Elaine

2018-01-01

Pregnancy may cause the onset of vaginal or vulvar varicosities that may be a concern for hemorrhage risk during childbirth. A 38-year-old female G4P1112 at 34 weeks and 1 day was referred to an outpatient OB/Gyn clinic for evaluation of a large vaginal mass. The referring provider had concern for malignancy. Lesions of the vulva were biopsied and found to be benign. For two months prior to presentation, she was experiencing discomfort with walking, yellow vaginal discharge, and dysuria. Treatment with fluconazole showed no improvement. She denied any personal or family history of malignancies, varicosities, or hepatic issues. Past surgical history was significant for laparoscopic cholecystectomy and two cesarean sections. A large vaginal mass during pregnancy is a concern whether it is malignancy or large vaginal varicosities that may put the patient at risk of severe hemorrhage during childbirth. We concluded that the mass was large vaginal varicosities as there was no discernible etiology. A repeat cesarean section was recommended due to the risk of hemorrhage during childbirth. For long-term management, close observation postpartum was recommended. Spontaneous resolution is a potential outcome and this is what our patient experienced. Without an underlying etiology, supportive measures are the best options.

Large Vaginal Varicosities in the Setting of Pregnancy without Known Hepatic or Vascular Risks: A Case Report and Review of the Literature

Directory of Open Access Journals (Sweden)

Mark Sueyoshi

2018-01-01

Full Text Available Pregnancy may cause the onset of vaginal or vulvar varicosities that may be a concern for hemorrhage risk during childbirth. A 38-year-old female G4P1112 at 34 weeks and 1 day was referred to an outpatient OB/Gyn clinic for evaluation of a large vaginal mass. The referring provider had concern for malignancy. Lesions of the vulva were biopsied and found to be benign. For two months prior to presentation, she was experiencing discomfort with walking, yellow vaginal discharge, and dysuria. Treatment with fluconazole showed no improvement. She denied any personal or family history of malignancies, varicosities, or hepatic issues. Past surgical history was significant for laparoscopic cholecystectomy and two cesarean sections. A large vaginal mass during pregnancy is a concern whether it is malignancy or large vaginal varicosities that may put the patient at risk of severe hemorrhage during childbirth. We concluded that the mass was large vaginal varicosities as there was no discernible etiology. A repeat cesarean section was recommended due to the risk of hemorrhage during childbirth. For long-term management, close observation postpartum was recommended. Spontaneous resolution is a potential outcome and this is what our patient experienced. Without an underlying etiology, supportive measures are the best options.

Oscillations of the positive column plasma due to ionization wave propagation and two-dimensional structure of striations

International Nuclear Information System (INIS)

Golubovskii, Yu B; Kozakov, R V; Wilke, C; Behnke, J; Nekutchaev, V O

2004-01-01

Time and space resolved measurements of the plasma potential in axial and radial directions in S- and P-striations in neon are performed. The measurements in different radial positions were carried out with high spatial resolution by means of simultaneous displacement of electrodes relative to the stationary probe. The plasma potential was found to be a superposition of the potentials of ionization wave and plasma oscillations relative to the electrodes. A method of decomposition of the measured spatio-temporal structure of the potential in components associated with the plasma oscillations and ionization wave propagation is proposed. A biorthogonal decomposition of the spatio-temporal structure of the potential is performed. A comparison of the decomposition results obtained by the two methods is made. The experiments revealed a two-dimensional structure of the potential field in an ionization wave. Qualitative discussions of the reasons for the occurrence of this two-dimensional structure are presented based on the analysis of the kinetic equation and the equation for the potential

Varicose vein therapy and nerve lesions.

Science.gov (United States)

Hirsch, Tobias

2017-03-01

Treating varicose veins using endovenous thermal techniques - especially laser and radio frequency ablation - has emerged as an effective alternative to open surgery with stripping and high ligation. Even though these methods are very gentle and patient-friendly, they are nevertheless accompanied by risks and side effects. Compared to open surgical therapy, the risk of damage to peripheral and motor nerves is reduced; however, it still exists as a result of heat exposure and tumescent anaesthesia. Non-thermal methods that can be applied without tumescent anaesthesia have been introduced to the market. They pose a considerably lower risk of nerve lesions while proving to be much more effective. This paper investigates data on postoperative nerve damage and paraesthesia using internet research (PubMed). It analyses the current state of knowledge regarding non-thermal treatment methods and takes into account the latest developments in the use of cyanoacrylate to close insufficient saphenous veins.

Microwave-Induced Magneto-Oscillations and Signatures of Zero-Resistance States in Phonon-Drag Voltage in Two-Dimensional Electron Systems.

Science.gov (United States)

Levin, A D; Momtaz, Z S; Gusev, G M; Raichev, O E; Bakarov, A K

2015-11-13

We observe the phonon-drag voltage oscillations correlating with the resistance oscillations under microwave irradiation in a two-dimensional electron gas in perpendicular magnetic field. This phenomenon is explained by the influence of dissipative resistivity modified by microwaves on the phonon-drag voltage perpendicular to the phonon flux. When the lowest-order resistance minima evolve into zero-resistance states, the phonon-drag voltage demonstrates sharp features suggesting that current domains associated with these states can exist in the absence of external dc driving.

Comparison of high ligation and stripping of the great saphenous vein combined with foam sclerotherapy versus conventional surgery for the treatment of superficial venous varicosities of the lower extremity

Science.gov (United States)

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

OSCIL: one-dimensional spring-mass system simulator for seismic analysis of high temperature gas cooled reactor core

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

OSCIL: one-dimensional spring-mass system simulator for seismic analysis of high temperature gas cooled reactor core

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.

Comparison of microbubble presence in the right heart during mechanochemical and radiofrequency ablation for varicose veins.

Science.gov (United States)

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.

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

Oscillator as a hidden non-Abelian monopole

International Nuclear Information System (INIS)

Mardoyan, L.G.; Sisakyan, A.N.; Ter-Antonyan, V.M.

1996-01-01

A non-Abelian SU(2) model is constructed for a five-dimensional bound system 'charge-dyon' on the basis of the Hurwitz-transformed eight-dimensional isotropic quantum oscillator. The principle of dyon-oscillator duality is formulated; the energy spectrum and wave functions of the system 'charge-dyon' are calculated. 20 refs

Lower limb gigantism, lymphedema, and painful varicosities following a thigh vascular access graft.

Science.gov (United States)

Thompson, Michael; Mathuram Thiyagarajan, Umasankar; Akoh, Jacob A

2014-07-01

Prosthetic arteriovenous grafts (AVGs) are associated with greater morbidity than autogenous arteriovenous fistulas (AVFs), but their use is indicated when AVF formation is not possible. This report adds to the literature a case of lower limb gigantism, painful varicosities, and lymphedema following long-term use of AVG in the upper thigh. The patient's past medical history included renal transplantation on the same side well before the AVG was inserted and right leg deep vein thrombosis. Suspicion of AVG thrombosis was excluded by Doppler ultrasound, which demonstrated an access flow of 1700 mL/min. A computed tomography (CT) scan of the abdomen and pelvis did not identify the cause of her symptoms. Whereas functional incompetence of the iliac vein valve might be responsible for the varicosities, the extent of hypertrophy in this case raises the suspicion of lymphatic blockage possibly secondary to groin dissection undertaken at the time of graft insertion, in addition to the previous dissection at the time of transplantation. This case highlights the need for minimal groin dissection during AVG insertion, particularly in patients with a history of previous abdominopelvic surgery. © 2014 International Society for Hemodialysis.

Biological findings from the PheWAS catalog: focus on connective tissue-related disorders (pelvic floor dysfunction, abdominal hernia, varicose veins and hemorrhoids).

Science.gov (United States)

Salnikova, Lyubov E; Khadzhieva, Maryam B; Kolobkov, Dmitry S

2016-07-01

Pelvic floor dysfunction, specifically genital prolapse (GP) and stress urinary inconsistency (SUI) presumably co-occur with other connective tissue disorders such as hernia, hemorrhoids, and varicose veins. Observations on non-random coexistence of these disorders have never been summarized in a meta-analysis. The performed meta-analysis demonstrated that varicose veins and hernia are associated with GP. Disease connections on the molecular level may be partially based on shared genetic susceptibility. A unique opportunity to estimate shared genetic susceptibility to disorders is provided by a PheWAS (phenome-wide association study) designed to utilize GWAS data concurrently to many phenotypes. We searched the PheWAS Catalog, which includes the results of the PheWAS study with P value hemorrhoids. We found pronounced signals for the associations of the SLC2A9 gene with SUI (P = 6.0e-05) and the MYH9 gene with varicose veins of lower extremity (P = 0.0001) and hemorrhoids (P = 0.0007). The comparison of the PheWAS Catalog and the NHGRI Catalog data revealed enrichment of genes associated with bone mineral density in GP and with activated partial thromboplastin time in varicose veins of lower extremity. In cross-phenotype associations, genes responsible for peripheral nerve functions seem to predominate. This study not only established novel biologically plausible associations that may warrant further studies but also exemplified an effective use of the PheWAS Catalog data.

Oscillation mode transformation of edge magnetoplasmons in two-dimensional electron system on liquid-helium surface

International Nuclear Information System (INIS)

Yamanaka, Shuji; Yayama, Hideki; Arai, Toshikazau; Anju Sawada, Anju; Fukuda, Akira

2013-01-01

We measured the resonance spectra of edge magnetoplasmon (EMP) oscillations in a two-dimensional (2D) electron system located on a liquid-helium surface below 1.1 K. Systematic measurements of the resonance frequency and the damping rate as a function of the lateral confinement electric field strength shows clear evidence of the oscillation mode transformation. A pronounced change corresponding to the mode transformation was observed in the damping rate. When 2D electrons are confined in a strong lateral electric field, the damping is weak. As the lateral confinement electric field is reduced below a certain threshold value, an abrupt enhancement of the damping rate is observed. We hypothesize that the weak damping mode in the strong lateral confinement electric field is the compressive density oscillation of the electrons near the edge (conventional EMP) and the strong damping mode in the weak confinement field is the coupled mode of conventional EMP and the boundary displacement wave (BDW). The observation of the strong damping in the BDW-EMP coupled mode is a manifestation of the nearly incompressible feature of strongly interacting classical electrons, which agrees with earlier theoretical predictions.

Three-dimensional vortex-induced vibrations of supported pipes conveying fluid based on wake oscillator models

Science.gov (United States)

Wang, L.; Jiang, T. L.; Dai, H. L.; Ni, Q.

2018-05-01

The present study develops a new three-dimensional nonlinear model for investigating vortex-induced vibrations (VIV) of flexible pipes conveying internal fluid flow. The unsteady hydrodynamic forces associated with the wake dynamics are modeled by two distributed van der Pol wake oscillators. In particular, the nonlinear partial differential equations of motion of the pipe and the wake are derived, taking into account the coupling between the structure and the fluid. The nonlinear equations of motion for the coupled system are then discretized by means of the Galerkin technique, resulting in a high-dimensional reduced-order model of the system. It is shown that the natural frequencies for in-plane and out-of-plane motions of the pipe may be different at high internal flow velocities beyond the threshold of buckling instability. The orientation angle of the postbuckling configuration is time-varying due to the disturbance of hydrodynamic forces, thus yielding sometimes unexpected results. For a buckled pipe with relatively low cross-flow velocity, interestingly, examining the nonlinear dynamics of the pipe indicates that the combined effects of the cross-flow-induced resonance of the in-plane first mode and the internal-flow-induced buckling on the IL and CF oscillation amplitudes may be significant. For higher cross-flow velocities, however, the effect of internal fluid flow on the nonlinear VIV responses of the pipe is not pronounced.

Polymerization and oscillation stuttering in a filamentous model of the subcellular Min oscillation

Science.gov (United States)

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.

[Variants of anatomical structure of lower-limb veins as a possible cause of the development of primary varicosity].

Science.gov (United States)

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

Ultrasonographic analysis in vitro of parietal thickness of lower limb varicose veins.

Science.gov (United States)

Bruschi, E; Como, G; Zuiani, C; Segatto, E; Rocco, M; Biasi, G; Bazzocchi, M

2006-09-01

The aim of this study was to evaluate the ability of ultrasound (US) to measure the parietal thickness of varicose veins. In a blind in vitro analysis, 28 great saphenous veins, obtained after stripping surgery from 28 patients with chronic venous insufficiency, were examined with a digital US scanner ATL-HDI5000, linear 5-1 to 2-MHz broadband probe, compound imaging technique and analogic-digital zooming. We obtained one to three progressive measurements for each vein wall (total 67 parietal thicknesses). The samples, fixed in formalin, were sent to the pathology laboratory: sections were obtained at the same level of the sonographic planes, and images were obtained by digital camera mounted on an optical microscope. Measurements obtained at histology were considered as the gold standard. K-statistic was applied to compare sonographic and histologic measurements. Considering only the hypoechoic wall portion, 29/29 (100%) diagnoses of hypotrophy (K=0.91), 19/22 (86%) diagnoses of normotrophy (K=0,47) and 12/16 (75%) diagnoses of hypertrophy (K=0.7) were obtained by sonography. In our preliminary experience, the in vitro study of varicose veins allows precise, at least morphological, detection of hypotrophic walls. If these preliminary data are confirmed in vivo, sonography could be used to discriminate patients eligible for conservative treatment instead of surgery.

Modelling of oscillations in two-dimensional echo-spectra of the Fenna-Matthews-Olson complex

International Nuclear Information System (INIS)

Hein, Birgit; Kreisbeck, Christoph; Kramer, Tobias; Rodríguez, Mirta

2012-01-01

Recent experimental observations of time-dependent beatings in the two-dimensional echo-spectra of light-harvesting complexes at ambient temperatures have opened up the question of whether coherence and wave-like behaviour play a significant role in photosynthesis. We carry out a numerical study of the absorption and echo-spectra of the Fenna-Matthews-Olson (FMO) complex in Chlorobium tepidum and analyse the requirements in the theoretical model needed to reproduce beatings in the calculated spectra. The energy transfer in the FMO pigment-protein complex is theoretically described by an exciton Hamiltonian coupled to a phonon bath which accounts for the pigments' electronic and vibrational excitations, respectively. We use the hierarchical equations of motions method to treat the strong couplings in a non-perturbative way. We show that the oscillations in the two-dimensional echo-spectra persist in the presence of thermal noise and static disorder. (paper)

Exacerbation of alopecia areata: A possible complication of sodium tetradecyl sulphate foam sclerotherapy treatment for varicose veins.

Science.gov (United States)

Whiteley, Mark S; Smith, Victoria C

2017-01-01

A 40-year-old woman with a history of alopecia areata related to stress or hormonal changes was treated for bilateral primary symptomatic varicose veins (CEAP clinical score C2S) of pelvic origin, using a staged procedure. Her first procedure entailed pelvic vein embolisation of three pelvic veins using 14 coils and including foam sclerotherapy of the tributaries, using 3% sodium tetradecyl sulphate. Following this procedure, she had an exacerbation of alopecia areata with some moderate shedding of hair. Subsequently, she underwent endovenous laser ablation under local anaesthetic without incident. Seven months after the pelvic vein embolisation, she underwent foam sclerotherapy of leg and labial varicose veins using sodium tetradecyl sulphate. Two days following this procedure, she had a severe exacerbation of alopecia areata with gross shedding of hair. These two episodes of exacerbation of alopecia areata appear to be associated with sodium tetradecyl sulphate foam sclerotherapy of veins.

[Early results after varicose vein surgery--a multicenter patient inquiry].

Science.gov (United States)

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.

Ginzburg-Landau-Gor close-quote kov theory of magnetic oscillations in a type-II two-dimensional superconductor

International Nuclear Information System (INIS)

Bruun, G.M.; Nicopoulos, V.N.; Johnson, N.F.

1997-01-01

We investigate de Haas endash van Alphen (dHvA) oscillations in the mixed state of a type-II two-dimensional superconductor within a self-consistent Gor close-quote kov perturbation scheme. Assuming that the order parameter forms a vortex lattice we can calculate the expansion coefficients exactly to any order. We have tested the results of the perturbation theory to fourth and eighth order against an exact numerical solution of the corresponding Bogoliubov endash de Gennes equations. The perturbation theory is found to describe well the onset of superconductivity close to the transition point H c2 . Contrary to earlier calculations by other authors we do not find that the perturbative scheme predicts any maximum of the dHvA oscillations below H c2 . Instead we obtain a substantial damping of the magnetic oscillations in the mixed state as compared to the normal state. We have examined the effect of an oscillatory chemical potential due to particle conservation and the effect of a finite Zeeman splitting. Furthermore, we have investigated the recently debated issue of the possibility of a sign change of the fundamental harmonic of the magnetic oscillations. Our theory is compared with experiment and we have found good agreement. copyright 1997 The American Physical Society

The Wigner distribution function for the one-dimensional parabose oscillator

International Nuclear Information System (INIS)

Jafarov, E; Lievens, S; Jeugt, J Van der

2008-01-01

In the beginning of the 1950s, Wigner introduced a fundamental deformation from the canonical quantum mechanical harmonic oscillator, which is nowadays sometimes called a Wigner quantum oscillator or a parabose oscillator. Also, in quantum mechanics the so-called Wigner distribution is considered to be the closest quantum analogue of the classical probability distribution over the phase space. In this paper, we consider which definition for such a distribution function could be used in the case of non-canonical quantum mechanics. We then explicitly compute two different expressions for this distribution function for the case of the parabose oscillator. Both expressions turn out to be multiple sums involving (generalized) Laguerre polynomials. Plots then show that the Wigner distribution function for the ground state of the parabose oscillator is similar in behaviour to the Wigner distribution function of the first excited state of the canonical quantum oscillator

The Effect of External Apple Vinegar Application on Varicosity Symptoms, Pain, and Social Appearance Anxiety: A Randomized Controlled Trial

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.

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.

State operator, constants of the motion, and Wigner functions: The two-dimensional isotropic harmonic oscillator

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....

Healthcare utilisation of pregnant women who experience sciatica, leg cramps and/or varicose veins: A cross-sectional survey of 1835 pregnant women.

Science.gov (United States)

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.

Exacerbation of alopecia areata: A possible complication of sodium tetradecyl sulphate foam sclerotherapy treatment for varicose veins

Directory of Open Access Journals (Sweden)

Mark S Whiteley

2017-05-01

Full Text Available A 40-year-old woman with a history of alopecia areata related to stress or hormonal changes was treated for bilateral primary symptomatic varicose veins (CEAP clinical score C2S of pelvic origin, using a staged procedure. Her first procedure entailed pelvic vein embolisation of three pelvic veins using 14 coils and including foam sclerotherapy of the tributaries, using 3% sodium tetradecyl sulphate. Following this procedure, she had an exacerbation of alopecia areata with some moderate shedding of hair. Subsequently, she underwent endovenous laser ablation under local anaesthetic without incident. Seven months after the pelvic vein embolisation, she underwent foam sclerotherapy of leg and labial varicose veins using sodium tetradecyl sulphate. Two days following this procedure, she had a severe exacerbation of alopecia areata with gross shedding of hair. These two episodes of exacerbation of alopecia areata appear to be associated with sodium tetradecyl sulphate foam sclerotherapy of veins.

Automatic Sieve-Shaker for Determining Soil Aggregate Stability and Dimensional Distribution Using a Vertical Oscillation System

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

Automatic Sieve-Shaker for Determining Soil Aggregate Stability and Dimensional Distribution Using a Vertical Oscillation System

Directory of Open Access Journals (Sweden)

Rosario Dell’Aquila

2007-12-01

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

Varicose vein surgery using a pneumatic tourniquet: reduced blood loss and improved cosmesis.

OpenAIRE

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...

Isotropic oscillator: spheroidal wave functions

International Nuclear Information System (INIS)

Mardoyan, L.G.; Pogosyan, G.S.; Ter-Antonyan, V.M.; Sisakyan, A.N.

1985-01-01

Solutions of the Schroedinger equation are found for an isotropic oscillator (10) in prolate and oblate spheroidal coordinates. It is shown that the obtained solutions turn into spherical and cylindrical bases of the isotropic oscillator at R→0 and R→ infinity (R is the dimensional parameter entering into the definition of prolate and oblate spheroidal coordinates). The explicit form is given for both prolate and oblate basis of the isotropic oscillator for the lowest quantum states

Photoinduced High-Frequency Charge Oscillations in Dimerized Systems

Science.gov (United States)

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.

Biomarkers of low-grade inflammation in primary varicose veins of the lower limbs.

Science.gov (United States)

Flore, R; Ponziani, F R; Gerardino, L; Santoliquido, A; Di Giorgio, A; Lupascu, A; Nesci, A; Tondi, P

2015-02-01

To analyze serum biomarkers of CVD in selected patients with primary axial reflux of great saphenous vein in one or both lower limbs. Ninety-six patients affected by uncomplicated varicose veins, were enrolled in the study. A unilateral, primary axial reflux in great saphenous veins was detected in 54 patients (U-CVD group) and a bilateral one in 42 (B-CVD group). Sixty-five age and sex-matched subjects without venous reflux were enrolled as controls. Mean venous pressure of both lower limbs at the distal great saphenous vein (mGSVP) and venous reflux were measured by continuous-wave Doppler ultrasound and echoduplex scanning, respectively. Reactive Oxygen Species (ROS), tissue Plasminogen Activator (t-PA) and its Inhibitor 1 (PAI-1) activities, Hematocrit (HTC), White Blood Cells (WBC), Neutrophyls (NEU), Platelets (PLT), Fibrinogen (FIB) and Blood Viscosity (BV) were assessed in blood samples drawn from the antecubital vein. B-CVD group showed higher fibrinogen values (p < 0.005) and higher mean venous pressure (0 < 0.0001) in comparison to controls, while U-CVD did not. No difference was found between both groups and controls for all the other parameters. Increased fibrinogen levels in patients with bilateral varicose veins may represent an early warning signal, as it could be associated to the long-term progression of chronic venous disease.

Global Classical and Weak Solutions to the Three-Dimensional Full Compressible Navier-Stokes System with Vacuum and Large Oscillations

Science.gov (United States)

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.

Fill and aspirate foam sclerotherapy (FAFS): a new approach for sclerotherapy of large superficial varicosities concomitant to endovenous laser ablation of truncal vein

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

The generation of two-dimensional vortices by transverse oscillation of a soap film

International Nuclear Information System (INIS)

Afenchenko, V.O.; Ezersky, A.B.; Kiyashko, S.V.; Rabinovich, M.I.; Weidman, P.D.

1998-01-01

An experimental investigation of the dynamics of horizontal soap films stretched over circular or square boundaries undergoing periodic transverse oscillations at frequencies in the range 20 - 200 Hz is reported. Concomitant with modes of transverse flexural oscillations, it was observed that two-dimensional vortices in the plane of the film are excited. The vortices may be either (i) large, scaling with the size of the cavity or (ii) small, localized at a wavelength or half-wavelength of the membrane modes. In the experiments a stable generation of one, two, hor-ellipsis, ten pairs of counter-rotating vortices were observed in finite regions of amplitude-frequency parameter space. The circulation strength of vortices in a given vortex pattern increases with increasing external forcing and with decreasing soap film thickness. A theoretical model based on the wave-boundary interaction of excited Marangoni waves reveals a vorticity generation mechanism active in vibrating soap films. This model shows that vorticity is generated throughout the entire liquid volume by viscous diffusion, and qualitatively reproduces many steady vortex patterns observed in the experiment. However, the model cannot explain the existence of the sometimes intense vortices observed far from the film boundary that do not appear to be generated by diffusive processes. copyright 1998 American Institute of Physics

Stochastic resonance induced by the novel random transitions of two-dimensional weak damping bistable duffing oscillator and bifurcation of moment equation

International Nuclear Information System (INIS)

Zhang Guangjun; Xu Jianxue; Wang Jue; Yue Zhifeng; Zou Hailin

2009-01-01

In this paper stochastic resonance induced by the novel random transitions of two-dimensional weak damping bistable Duffing oscillator is analyzed by moment method. This kind of novel transition refers to the one among three potential well on two sides of bifurcation point of original system at the presence of internal noise. Several conclusions are drawn. First, the semi-analytical result of stochastic resonance induced by the novel random transitions of two-dimensional weak damping bistable Duffing oscillator can be obtained, and the semi-analytical result is qualitatively compatible with the one of Monte Carlo simulation. Second, a bifurcation of double-branch fixed point curves occurs in the moment equations with noise intensity as their bifurcation parameter. Third, the bifurcation of moment equations corresponds to stochastic resonance of original system. Finally, the mechanism of stochastic resonance is presented from another viewpoint through analyzing the energy transfer induced by the bifurcation of moment equation.

Exact folded-band chaotic oscillator.

Science.gov (United States)

Corron, Ned J; Blakely, Jonathan N

2012-06-01

An exactly solvable chaotic oscillator with folded-band dynamics is shown. The oscillator is a hybrid dynamical system containing a linear ordinary differential equation and a nonlinear switching condition. Bounded oscillations are provably chaotic, and successive waveform maxima yield a one-dimensional piecewise-linear return map with segments of both positive and negative slopes. Continuous-time dynamics exhibit a folded-band topology similar to Rössler's oscillator. An exact solution is written as a linear convolution of a fixed basis pulse and a discrete binary sequence, from which an equivalent symbolic dynamics is obtained. The folded-band topology is shown to be dependent on the symbol grammar.

Many-dimensional anisotropic anharmonic oscillator

International Nuclear Information System (INIS)

Turbiner, A.V.

1987-01-01

Precision calculation of energies of several first states at d=2 and first 17 states at d=3 has been performed within the framework of a unique method based on ''nonlinearization'' method for d-dimension anisotropic an harmonic oscillator. Spectrum behaviour within the limit d → ∞ has been investigated and problems of the given approach accuracy have been studied. For the first time properties of nodal surfaces of the given task have been investigated. Routine perturbation theory in degrees of a perturbation parameter has been constructed for several first states

Detecting Friedel oscillations in ultracold Fermi gases

Science.gov (United States)

Riechers, Keno; Hueck, Klaus; Luick, Niclas; Lompe, Thomas; Moritz, Henning

2017-09-01

Investigating Friedel oscillations in ultracold gases would complement the studies performed on solid state samples with scanning-tunneling microscopes. In atomic quantum gases interactions and external potentials can be tuned freely and the inherently slower dynamics allow to access non-equilibrium dynamics following a potential or interaction quench. Here, we examine how Friedel oscillations can be observed in current ultracold gas experiments under realistic conditions. To this aim we numerically calculate the amplitude of the Friedel oscillations which are induced by a potential barrier in a 1D Fermi gas and compare it to the expected atomic and photonic shot noise in a density measurement. We find that to detect Friedel oscillations the signal from several thousand one-dimensional systems has to be averaged. However, as up to 100 parallel one-dimensional systems can be prepared in a single run with present experiments, averaging over about 100 images is sufficient.

[Modern approach to treatment of trophic ulcers of legs with perifocal varicose eczema, associated with mycotic infection].

Science.gov (United States)

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

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......-dimensional system with an initial singularity, subdivision of the first time interval into a number of equal subintervals (the Pearson method) works rather well, and so does division with exponentially increasing subintervals, where however an optimum expansion parameter must be found. This method can...... 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...

Magnetoresistance oscillations of two-dimensional electron systems in lateral superlattices with structured unit cells

Science.gov (United States)

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.

Moving heat source in a confined channel: Heat transfer and boiling in endovenous laser ablation of varicose veins

NARCIS (Netherlands)

de Boer, Amit; Oliveira, Jorge L. G.; van der Geld, Cees W. M.; Malskat, Wendy S. J.; van den Bos, Renate; Nijsten, Tamar; van Gemert, Martin J. C.

2017-01-01

Motion of a moving laser light heat source in a confined volume has important applications such as in endovenous laser ablation (EVLA) of varicose veins. This light heats up the fluid and the wall volume by absorption and heat conduction. The present study compares the flow and temperature fields in

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

Atypical leg ulcers after sclerotherapy for treatment of varicose veins: Case reports and literature review

OpenAIRE

Mwipatayi, Bibombe P.; Western, Catherine E.; Wong, Jackie; Angel, Donna

2016-01-01

Introduction: Skin necrosis is a rare complication of foam sclerotherapy, a common form of treatment for varicose veins. Presentation of case: Both patients presented to the outpatient clinic within 2–14 days after foam sclerotherapy with Aethoxysklerol® 1%, with severe soft tissue and skin necrosis. Further aggressive treatment of the ulcer was required to resolve the necrosis, resulting in marked residual scar and well granulated leg ulcer respectively. Discussion: Foam sclerotherapy ...

Coupled oscillators with parity-time symmetry

Energy Technology Data Exchange (ETDEWEB)

Tsoy, Eduard N., E-mail: etsoy@uzsci.net

2017-02-05

Different models of coupled oscillators with parity-time (PT) symmetry are studied. Hamiltonian functions for two and three linear oscillators coupled via coordinates and accelerations are derived. Regions of stable dynamics for two coupled oscillators are obtained. It is found that in some cases, an increase of the gain-loss parameter can stabilize the system. A family of Hamiltonians for two coupled nonlinear oscillators with PT-symmetry is obtained. An extension to high-dimensional PT-symmetric systems is discussed. - Highlights: • A generalization of a Hamiltonian system of linear coupled oscillators with the parity-time (PT) symmetry is suggested. • It is found that an increase of the gain-loss parameter can stabilize the system. • A family of Hamiltonian functions for two coupled nonlinear oscillators with PT-symmetry is obtained.

One-dimensional Fermi accelerator model with moving wall described by a nonlinear van der Pol oscillator.

Science.gov (United States)

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.

Fluoroscopy-guided endovenous sclerotherapy using a microcatheter prior to endovenous laser ablation: Comparison between liquid and foam sclerotherapy for varicose tributaries

Energy Technology Data Exchange (ETDEWEB)

Park, Sang Woo; Yun, Ik Jin; Hwang, Jae Joon; Lee, Song Am; Kim, Jun Seok; Chee, Hyun Keun; Chang, Il Soo [Konkuk University Hospital, Konkuk University School of Medicine, Seoul (Korea, Republic of)

2014-08-15

To compare the efficacy and adverse effects of endovenous foam sclerotherapy (EFS) and liquid sclerotherapy (ELS) using a microcatheter for the treatment of varicose tributaries. From December 2007 to January 2009, patients with venous reflux in the saphenous vein were enrolled. The foam or liquid sclerosant was injected through a microcatheter just before endovenous laser ablation (EVLA). Patients were evaluated for the technical success, clinical success, and procedure-related complications during the procedure and follow-up visits. A total of 94 limbs were included: 48 limbs (great saphenous vein [GSV], 35; small saphenous vein [SSV], 13) were managed using EFS and EVLA (foam group; FG), and 46 limbs (GSV, 37; SSV, 9) were treated by ELS and EVLA (liquid group; LG). Varicose tributaries demonstrated complete sclerosis in 92.7% with FG and in 71.8% with LG (p = 0.014). Bruising (78.7% in FG vs. 73.2% in LG, p > 0.05), pain or tenderness (75.6% in FG vs. 51.2% in LG, p = 0.0237) were noted. Hyperpigmentation (51.2% in FG vs. 46.2% in LG, p > 0.05) was found. Endovenous foam sclerotherapy using a microcatheter is more effective than ELS for eliminating remnant varicose tributaries prior to EVLA. However, EFS is more commonly associated with local complications such as pain or tenderness than ELS. Furthermore, both techniques seem to prolong the duration of hyperpigmentation along with higher costs.

Origin of fine oscillations in the photoluminescence spectrum of 2-dimensional electron gas formed in AlGaN/GaN high electron mobility transistor structures

Energy Technology Data Exchange (ETDEWEB)

Jana, Dipankar, E-mail: dip2602@gmail.com; Porwal, S.; Oak, S. M.; Sharma, T. K., E-mail: tarun@rrcat.gov.in [Semiconductor Physics and Devices Laboratory, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Jain, Anubha [Solid State Physics Laboratory, Lucknow Road, New Delhi 110054 (India)

2015-10-28

An unambiguous identification of the fine oscillations observed in the low temperature photoluminescence (PL) spectra of AlGaN/GaN based high electron mobility transistor (HEMT) structures is carried out. In literature, such oscillations have been erroneously identified as the sub-levels of 2-dimensional electron gas (2DEG) formed at AlGaN/GaN heterointerface. Here, the origin of these oscillations is probed by performing the angle dependent PL and reflectivity measurements under identical conditions. Contrary to the reports available in literature, we find that the fine oscillations are not related to 2DEG sub-levels. The optical characteristics of these oscillations are mainly governed by an interference phenomenon. In particular, peculiar temperature dependent redshift and excitation intensity dependent blueshift, which have been interpreted as the characteristics of 2DEG sub-levels in HEMT structures by other researchers, are understood by invoking the wavelength and temperature dependence of the refractive index of GaN within the framework of interference phenomenon. The results of other researchers are also consistently explained by considering the fine oscillatory features as the interference oscillations.

Three-dimensional analyses of ultrasonic scaler oscillations.

Science.gov (United States)

Lea, Simon C; Felver, Bernhard; Landini, Gabriel; Walmsley, A Damien

2009-01-01

It is stated that the oscillation patterns of dental ultrasonic scalers are dependent upon whether the instrument is of a magnetostrictive or piezoelectric design. These patterns are then linked to differences in root surface debridement in vitro. Piezoelectric (A, P) and magnetostrictive (Slimline, TFI-3) ultrasonic scalers (three of each) were evaluated, loaded (100 g/200 g) and unloaded with a 3D laser vibrometer. Loads were applied to the probe tips via teeth mounted in a load-measuring device. Elliptical motion was demonstrated for all probes under loaded and unloaded conditions. Loading flattened the elliptical motion along the length of the probe. Unloaded, Slimline tip 1 was significantly different to tips 2 and 3 (p0.207). All TFI-3 tips were different to each other (p0.867). Generator power increased all Slimline and P tip vibrations (pultrasound production mechanism and are dependent upon probe shape and generator power. Loaded probes oscillated with an elliptical pattern.

Topological and trivial magnetic oscillations in nodal loop semimetals

Science.gov (United States)

Oroszlány, László; Dóra, Balázs; Cserti, József; Cortijo, Alberto

2018-05-01

Nodal loop semimetals are close descendants of Weyl semimetals and possess a topologically dressed band structure. We argue by combining the conventional theory of magnetic oscillation with topological arguments that nodal loop semimetals host coexisting topological and trivial magnetic oscillations. These originate from mapping the topological properties of the extremal Fermi surface cross sections onto the physics of two dimensional semi-Dirac systems, stemming from merging two massless Dirac cones. By tuning the chemical potential and the direction of magnetic field, a sharp transition is identified from purely trivial oscillations, arising from the Landau levels of a normal two dimensional (2D) electron gas, to a phase where oscillations of topological and trivial origin coexist, originating from 2D massless Dirac and semi-Dirac points, respectively. These could in principle be directly identified in current experiments.

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

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

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)

The Two-Beam Free Electron Laser Oscillator

CERN Document Server

Thompson, Neil R

2004-01-01

A one-dimensional model of a free-electron laser operating simultaneously with two electron beams of different energies [1] is extended to an oscillator configuration. The electron beam energies are chosen so that an harmonic of the lower energy beam is at the fundamental radiation wavelength of the higher energy beam. Potential benefits over a single-beam free-electron laser oscillator are discussed.

A one-dimensional model illustrating virtual-cathode formation in a novel coaxial virtual-cathode oscillator

International Nuclear Information System (INIS)

Turner, Geoffrey R.

2014-01-01

A one-dimensional electrostatic sheet model of a coaxial geometry Virtual Cathode Oscillator (VCO) is presented. The cathode is centrally located and connects to a peripherally located plate electrode to form a resonant cavity, and is thus considered to be a novel design. Charge is modelled as concentric sheets about the cathode whose absolute position and velocity are determined as a function of time by solving the relativistic equations of motion. The model predicts the formation of a virtual cathode between the grid and plate electrodes for the case of a space-charge limited current. Setting the electron reflexing frequency (as a function of the grid potential) comparable with the cavity resonant frequency is predicted to improve the efficiency of microwave emission

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)

On the connection between the hydrogen atom and the harmonic oscillator: the continuum case

International Nuclear Information System (INIS)

Kibler, M.; Negadi, T.

1983-05-01

The connection between a three-dimensional nonrelativistic hydrogen atom with positive energy and a four-dimensional isotropic harmonic oscillator with repulsive potential is established by applying Jordan-Schwinger boson calculus to the algebra of the Laplace-Runge-Lenz-Pauli vector. The spectrum generating group SO(4,2) both for the bound and free states of the three-dimensional hydrogen atom arises as a quotient of the group Sp(8,R) associated to a four-dimensional isotropic harmonic oscillator with constraint

Reduction theories elucidate the origins of complex biological rhythms generated by interacting delay-induced oscillations.

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.

One-dimensional multiple-well oscillators: A time-dependent

Indian Academy of Sciences (India)

... quantum mechanical multiple-well oscillators. An imaginary-time evolution technique, coupled with the minimization of energy expectation value to reach a global minimum, subject to orthogonality constraint (for excited states) has been employed. Pseudodegeneracy in symmetric, deep multiple-well potentials, probability ...

The clinical study of 2D and power doppler ultrasound in esophagus varix

International Nuclear Information System (INIS)

Li Qiang; Zhou Liang; Zhang Yucheng; Yang Minghua; Ruan Fenglian; Lu Haixia; Li Yue

2008-01-01

Objective: To study the application of 2D and Power Doppler Ultrasound in diagnosing the abdominal esophageal varicose veins. Methods: 65 patients under suspicion with chronic hepatitis and cirrhosis for esophageal varicose at esophagus in abdomen section were examined by 2D and Power Doppler Ultrasound.Among them, 35 patients suffered from esophageal varicose veins proved by gastroscopy and the rest did not. Results: On the power doppler imaging map, colored blood stream signals were showed in varicose veins while without signals in non-varicose veins.The diagnostic sensitivity and specificity were 91.4% and 100% respectively. On the two-dimensional image chart, non-echoes were represented in varicose veins. The anteroposterior diameter, right-left diameter, as well as the thickness of esophagus wall were larger in patients with varicose veins than those in non varicose veins cases (P<0.01). Conclusion: 2D combined with Power Doppler Ultrasound was of non-invasive, safe, sensitive and high specificity, which is a valuable and practical tool in diagnosing the esophageal varicose veins. (authors)

Development of a three-dimensional dynamic biped walking via the oscillation of telescopic knee joint and its gait analysis

Directory of Open Access Journals (Sweden)

T. Kinugasa

2015-12-01

Full Text Available The purpose of this study is to extend the three-dimensional (3-D passive dynamic biped walker to a 3-D dynamic biped walker, i.e., a walker that can walk on a horizontal surface based on a passive dynamic walking. A new prototype of 3-D biped walker called RW04, which has telescopic knee joints, was developed and its ability for walking was validated through some experiments. A sinusoidal oscillation, which is regarded as a central pattern generator with no sensory feedback, was provided to the knee joints to achieve the biped walking. The results showed that the biped gait of RW04 was possible only via a sinusoidal oscillation of the knee joint. Moreover, the 3-D dynamic walking gait via frequency response and zero moment point (ZMP trajectory was also analyzed. The biped locomotion had a resonance, i.e., the frequency matched the natural frequency of the locomotion in the gain property. An “8” shaped ZMP trajectory was observed, which was found to be similar to that of the human gait. However, the simple sinusoidal oscillation had limitations such as stride reduction or discontinuation by phase difference. Therefore, in future work, more adaptable control strategy such as a sensory feedback using ZMP should be provided.

Plasma properties of quasi-one-dimensional ring

CERN Document Server

Shmelev, G M

2001-01-01

The plasma properties of the quasi-one-dimensional ring in the threshold cases of low and high frequencies, corresponding to the plasma oscillations and dielectric relaxation are studied within the frames of the classical approach. The plasma oscillations spectrum and the electron dielectric relaxation frequency in the quasi-one-dimensional ring are calculated. The plasmons spectrum equidistance is identified. It is shown , that in contrast to the three-dimensional case there takes place the dielectric relaxation dispersion, wherefrom there follows the possibility of studying the carriers distribution in the quasi-one-dimensional rings through the method of the dielectric relaxation spectroscopy

Complex behavior in chains of nonlinear oscillators.

Science.gov (United States)

Alonso, Leandro M

2017-06-01

This article outlines sufficient conditions under which a one-dimensional chain of identical nonlinear oscillators can display complex spatio-temporal behavior. The units are described by phase equations and consist of excitable oscillators. The interactions are local and the network is poised to a critical state by balancing excitation and inhibition locally. The results presented here suggest that in networks composed of many oscillatory units with local interactions, excitability together with balanced interactions is sufficient to give rise to complex emergent features. For values of the parameters where complex behavior occurs, the system also displays a high-dimensional bifurcation where an exponentially large number of equilibria are borne in pairs out of multiple saddle-node bifurcations.

Neuromorphic computing with nanoscale spintronic oscillators.

Science.gov (United States)

Torrejon, Jacob; Riou, Mathieu; Araujo, Flavio Abreu; Tsunegi, Sumito; Khalsa, Guru; Querlioz, Damien; Bortolotti, Paolo; Cros, Vincent; Yakushiji, Kay; Fukushima, Akio; Kubota, Hitoshi; Yuasa, Shinji; Stiles, Mark D; Grollier, Julie

2017-07-26

Neurons in the brain behave as nonlinear oscillators, which develop rhythmic activity and interact to process information. Taking inspiration from this behaviour to realize high-density, low-power neuromorphic computing will require very large numbers of nanoscale nonlinear oscillators. A simple estimation indicates that to fit 10 8 oscillators organized in a two-dimensional array inside a chip the size of a thumb, the lateral dimension of each oscillator must be smaller than one micrometre. However, nanoscale devices tend to be noisy and to lack the stability that is required to process data in a reliable way. For this reason, despite multiple theoretical proposals and several candidates, including memristive and superconducting oscillators, a proof of concept of neuromorphic computing using nanoscale oscillators has yet to be demonstrated. Here we show experimentally that a nanoscale spintronic oscillator (a magnetic tunnel junction) can be used to achieve spoken-digit recognition with an accuracy similar to that of state-of-the-art neural networks. We also determine the regime of magnetization dynamics that leads to the greatest performance. These results, combined with the ability of the spintronic oscillators to interact with each other, and their long lifetime and low energy consumption, open up a path to fast, parallel, on-chip computation based on networks of oscillators.

Scaling Laws in the Transient Dynamics of Firefly-like Oscillators

International Nuclear Information System (INIS)

Rubido, N; Cabeza, C; Marti, A; Ramirez Avila, G M

2011-01-01

Fireflies constitute a paradigm of pulse-coupled oscillators. In order to tackle the problems related to synchronisation transients of pulse-coupled oscillators, a Light-Controlled Oscillator (LCO) model is presented. A single LCO constitutes a one-dimensional relaxation oscillator described by two distinct time-scales meant to mimic fireflies in the sense that: it is capable of emitting light in a pulse-like fashion and detect the emitted by others in order to adjust its oscillation. We present dynamical results for two interacting LCOs in the torus for all possible coupling configurations. Transient times to the synchronous limit cycle are obtained experimentally and numerically as a function of initial conditions and coupling strengths. Scaling laws are found based on dimensional analysis and critical exponents calculated, thus, global dynamic is restricted. Furthermore, an analytical orthogonal transformation that allows to calculate Floquet multipliers directly from the time series is presented. As a consequence, local dynamics is also fully characterized. This transformation can be easily extended to a system with an arbitrary number of interacting LCOs.

Exacerbation of alopecia areata: A possible complication of sodium tetradecyl sulphate foam sclerotherapy treatment for varicose veins

OpenAIRE

Whiteley, Mark S; Smith, Victoria C

2017-01-01

A 40-year-old woman with a history of alopecia areata related to stress or hormonal changes was treated for bilateral primary symptomatic varicose veins (CEAP clinical score C2S) of pelvic origin, using a staged procedure. Her first procedure entailed pelvic vein embolisation of three pelvic veins using 14 coils and including foam sclerotherapy of the tributaries, using 3% sodium tetradecyl sulphate. Following this procedure, she had an exacerbation of alopecia areata with some moderate shedd...

Two-and-one-half-dimensional magnetohydrodynamic simulations of the plasma sheet in the presence of oxygen ions: The plasma sheet oscillation and compressional Pc 5 waves

International Nuclear Information System (INIS)

Lu Li; Liu Zhenxing; Cao Jinbin

2002-01-01

Two-and-one-half-dimensional magnetohydrodynamic simulations of the multicomponent plasma sheet with the velocity curl term in the magnetic equation are represented. The simulation results can be summarized as follows: (1) There is an oscillation of the plasma sheet with the period on the order of 400 s (Pc 5 range); (2) the magnetic equator is a node of the magnetic field disturbance; (3) the magnetic energy integral varies antiphase with the internal energy integral; (4) disturbed waves have a propagating speed on the order of 10 km/s earthward; (5) the abundance of oxygen ions influences amplitude, period, and dissipation of the plasma sheet oscillation. It is suggested that the compressional Pc 5 waves, which are observed in the plasma sheet close to the magnetic equator, may be caused by the plasma sheet oscillation, or may be generated from the resonance of the plasma sheet oscillation with some Pc 5 perturbation waves coming from the outer magnetosphere

Systematic design and three-dimensional simulation of X-ray FEL oscillator for Shanghai Coherent Light Facility

Science.gov (United States)

Li, Kai; Deng, Haixiao

2018-07-01

The Shanghai Coherent Light Facility (SCLF) is a quasi-continuous wave hard X-ray free electron laser facility, which is currently under construction. Due to the high repetition rate and high-quality electron beams, it is straightforward to consider X-ray free electron laser oscillator (XFELO) operation for the SCLF. In this paper, the main processes for XFELO design, and parameter optimization of the undulator, X-ray cavity, and electron beam are described. A three-dimensional X-ray crystal Bragg diffraction code, named BRIGHT, was introduced for the first time, which can be combined with the GENESIS and OPC codes for the numerical simulations of the XFELO. The performance of the XFELO of the SCLF is investigated and optimized by theoretical analysis and numerical simulation.

Dynamic hysteresis behaviors for the two-dimensional mixed spin (2, 5/2) ferrimagnetic Ising model in an oscillating magnetic field

Science.gov (United States)

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.

Huge Varicose Inferior Mesenteric Vein: an Unanticipated 99mTc-labeled Red Blood Cell Scintigraphy Finding

International Nuclear Information System (INIS)

Hoseinzadeh, Samaneh; Shafiei, Babak; Salehian, Mohamadtaghi; Neshandar Asli, Isa; Ghodoosi, Iraj

2010-01-01

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 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 99m Tc-labeled RBC scintigraphy for the diagnosis of rare ectopic lower GI varices.

Self-sustained oscillations of complex genomic regulatory networks

International Nuclear Information System (INIS)

Ye Weiming; Huang Xiaodong; Huang Xuhui; Li Pengfei; Xia Qinzhi; Hu Gang

2010-01-01

Recently, self-sustained oscillations in complex networks consisting of non-oscillatory nodes have attracted great interest in diverse natural and social fields. Oscillatory genomic regulatory networks are one of the most typical examples of this kind. Given an oscillatory genomic network, it is important to reveal the central structure generating the oscillation. However, if the network consists of large numbers of genes and interactions, the oscillation generator is deeply hidden in the complicated interactions. We apply the dominant phase-advanced driving path method proposed in Qian et al. (2010) to reduce complex genomic regulatory networks to one-dimensional and unidirectionally linked network graphs where negative regulatory loops are explored to play as the central generators of the oscillations, and oscillation propagation pathways in the complex networks are clearly shown by tree branches radiating from the loops. Based on the above understanding we can control oscillations of genomic networks with high efficiency.

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.

Periodic synchronization and chimera in conformist and contrarian oscillators

Science.gov (United States)

Hong, Hyunsuk

2014-06-01

We consider a system of phase oscillators that couple with both attractive and repulsive interaction under a pinning force and explore collective behavior of the system. The oscillators can be divided into two subpopulations of "conformist" oscillators with attractive interaction and "contrarian" ones with repulsive interaction. We find that the interplay between the pinning force and the opposite relationship of the conformist and contrarian oscillators induce peculiar dynamic states: periodic synchronization, breathing chimera, and fully pinned state depending on the fraction of the conformists. Using the Watanabe-Strogatz transformation, we reduce the dynamics into a low-dimensional one and find that the above dynamic states are generated from the reduced dynamics.

Changes of blood levels of LPO, SOD and GSH-Px after endovenous laser treatment of varicose greater saphenous vein

International Nuclear Information System (INIS)

Han Li'na; Gu Ying; Liu Fanguang

2004-01-01

Objective: To investigate the changes of the blood levels of lipid peroxide (LPO), superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) after treatment of varicose greater saphenous vein with either endovenous laser or conventional surgery (high ligation plus stripping). Methods: Thirty-seven patients with varicose greater saphenous vein were treated with endovenous laser and another 33 patients were treated with conventional surgery. Levels of LPO (serum, with TBA fluorescein), SOD (whole blood, with RIA) and GSH-Px (whole blood, with direct DTNB) were determined in these patients both before and 1, 3, 5, 7, 10, 15 days after treatment. Levels in 30 controls were also measured. Results: The levels of LPO were higher and levels of SOD, GSH-Px lower in the patients than those in the controls. After either form of therapy, the levels LPO rose and levels of SOD, GSH-Px dropped immediately but gradually approached the control values by the 15 th day (slower with SOD and GSH-Px). However, the early increase of LPO levels were less and recovery sooner in the group of patients treated with laser. Conclusion: Changes of levels of LPO, SOD and GSH-Px were closely related to the degree of stress and recovery condition after the treatment

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...... 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...

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.)

Analytical Expressions of Matrix Elements of Physical Quantities for Dirac Oscillator

Institute of Scientific and Technical Information of China (English)

LI Ning; JU Guo-Xing; REN Zhong-Zhou

2004-01-01

The analytical expressions of the matrix elements for physical quantities are obtained for the Dirac oscillator in two and three spatial dimensions. Their behaviour for the case of operator's square is discussed in details. The twodimensional Dirac oscillator has similar behavior to that for three-dimensional one.

A new family of N dimensional superintegrable double singular oscillators and quadratic algebra Q(3) ⨁ so(n) ⨁ so(N-n)

Science.gov (United States)

Fazlul Hoque, Md; Marquette, Ian; Zhang, Yao-Zhong

2015-11-01

We introduce a new family of N dimensional quantum superintegrable models consisting of double singular oscillators of type (n, N-n). The special cases (2,2) and (4,4) have previously been identified as the duals of 3- and 5-dimensional deformed Kepler-Coulomb systems with u(1) and su(2) monopoles, respectively. The models are multiseparable and their wave functions are obtained in (n, N-n) double-hyperspherical coordinates. We obtain the integrals of motion and construct the finitely generated polynomial algebra that is the direct sum of a quadratic algebra Q(3) involving three generators, so(n), so(N-n) (i.e. Q(3) ⨁ so(n) ⨁ so(N-n)). The structure constants of the quadratic algebra itself involve the Casimir operators of the two Lie algebras so(n) and so(N-n). Moreover, we obtain the finite dimensional unitary representations (unirreps) of the quadratic algebra and present an algebraic derivation of the degenerate energy spectrum of the superintegrable model.

Effects of core models and neutron energy group structures on xenon oscillation in large graphite-moderated reactors

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)

Weiss oscillations and particle-hole symmetry at the half-filled Landau level

Science.gov (United States)

Cheung, Alfred K. C.; Raghu, S.; Mulligan, Michael

2017-06-01

Particle-hole symmetry in the lowest Landau level of the two-dimensional electron gas requires the electrical Hall conductivity to equal ±e2/2 h at half filling. We study the consequences of weakly broken particle-hole symmetry for magnetoresistance oscillations about half filling in the presence of an applied periodic one-dimensional electrostatic potential using the Dirac composite fermion theory proposed by Son [Son, Phys. Rev. X 5, 031027 (2015), 10.1103/PhysRevX.5.031027]. At fixed electron density, the oscillation minima are asymmetrically biased towards higher magnetic fields, while at fixed magnetic field the oscillations occur symmetrically as the electron density is varied about half filling. We find an approximate "sum rule" obeyed for all pairs of oscillation minima that can be tested in experiment. The locations of the magnetoresistance oscillation minima for the composite fermion theory of Halperin, Lee, and Read (HLR) and its particle-hole conjugate agree exactly. Within the current experimental resolution, the locations of the oscillation minima produced by the Dirac composite fermion coincide with those of HLR. These results may indicate that all three composite fermion theories describe the same long-wavelength physics.

Huge Varicose Inferior Mesenteric Vein: an Unanticipated {sup 99m}Tc-labeled Red Blood Cell Scintigraphy Finding

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.

Evaluation of thermal margin during BWR neutron flux oscillation

International Nuclear Information System (INIS)

Takeuchi, Yutaka; Takigawa, Yukio; Chuman, Kazuto; Ebata, Shigeo

1992-01-01

Fuel integrity is very important, from the view point of nuclear power plant safety. Recently, neutron flux oscillations were observed at several BWR plants. The present paper describes the evaluations of the thermal margin during BWR neutron flux oscillations, using a three-dimensional transient code. The thermal margin is evaluated as MCPR (minimum critical power ratio). The LaSalle-2 event was simulated and the MCPR during the event was evaluated. It was a core-wide oscillation, at which a large neutron flux oscillation amplitude was observed. The results indicate that the MCPR had a sufficient margin with regard to the design limit. A regional oscillation mode, which is different from a core-wide oscillation, was simulated and the MCPR response was compared with that for the LaSalle-2 event. The MCPR decrement is greater in the regional oscillation, than in the core wide -oscillation, because of the sensitivity difference in a flow-to-power gain. A study was carried out about regional oscillation detectability, from the MCPR response view point. Even in a hypothetically severe case, the regional oscillation is detectable by LPRM signals. (author)

Discrete repulsive oscillator wavefunctions

International Nuclear Information System (INIS)

Munoz, Carlos A; Rueda-Paz, Juvenal; Wolf, Kurt Bernardo

2009-01-01

For the study of infinite discrete systems on phase space, the three-dimensional Lorentz algebra and group, so(2,1) and SO(2,1), provide a discrete model of the repulsive oscillator. Its eigenfunctions are found in the principal irreducible representation series, where the compact generator-that we identify with the position operator-has the infinite discrete spectrum of the integers Z, while the spectrum of energies is a double continuum. The right- and left-moving wavefunctions are given by hypergeometric functions that form a Dirac basis for l 2 (Z). Under contraction, the discrete system limits to the well-known quantum repulsive oscillator. Numerical computations of finite approximations raise further questions on the use of Dirac bases for infinite discrete systems.

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.)

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)

The macroscopic harmonic oscillator and quantum measurements

International Nuclear Information System (INIS)

Hayward, R.W.

1982-01-01

A quantum mechanical description of a one-dimensional macroscopic harmonic oscillator interacting with its environment is given. Quasi-coherent states are introduced to serve as convenient basis states for application of a density matrix formalism to characterize the system. Attention is given to the pertinent quantum limits to the precision of measurement of physical observables that may provide some information on the nature of a weak classical force interacting with the oscillator. A number of ''quantum nondemolition'' schemes proposed by various authors are discussed. (Auth.)

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

Oscillator representations for self-adjoint Calogero Hamiltonians

Energy Technology Data Exchange (ETDEWEB)

Gitman, D M [Institute of Physics, University of Sao Paulo (Brazil); Tyutin, I V; Voronov, B L, E-mail: gitman@dfn.if.usp.br, E-mail: tyutin@lpi.ru, E-mail: voronov@lpi.ru [Lebedev Physical Institute, Moscow (Russian Federation)

2011-10-21

In Gitman et al (2010 J. Phys. A: Math. Theor. 43 145205), we presented a mathematically rigorous quantum-mechanical treatment of a one-dimensional motion of a particle in the Calogero potential V(x) = {alpha}x{sup -2}. We described all possible self-adjoint (s.a.) operators (s.a. Hamiltonians) associated with the differential operation H=-d{sub x}{sup 2}+{alpha}x{sup -2} for the Calogero Hamiltonian. Here, we discuss a new aspect of the problem, the so-called oscillator representations for the Calogero Hamiltonians. As is known, operators of the form N-hat = a-hat{sup +} a-hat and A-hat = a-hat a-hat{sup +} are called operators of oscillator type. Oscillator-type operators possess a number of useful properties in the case when the elementary operators a-hat are closed. It turns out that some s.a. Calogero Hamiltonians allow oscillator-type representations. We describe such Hamiltonians and find the corresponding mutually adjoint elementary operators a-hat and a-hat{sup +}. An oscillator-type representation for a given Hamiltonian is generally not unique. (paper)

Oscillator representations for self-adjoint Calogero Hamiltonians

International Nuclear Information System (INIS)

Gitman, D M; Tyutin, I V; Voronov, B L

2011-01-01

In Gitman et al (2010 J. Phys. A: Math. Theor. 43 145205), we presented a mathematically rigorous quantum-mechanical treatment of a one-dimensional motion of a particle in the Calogero potential V(x) = αx -2 . We described all possible self-adjoint (s.a.) operators (s.a. Hamiltonians) associated with the differential operation H=-d x 2 +αx -2 for the Calogero Hamiltonian. Here, we discuss a new aspect of the problem, the so-called oscillator representations for the Calogero Hamiltonians. As is known, operators of the form N-hat = a-hat + a-hat and A-hat = a-hat a-hat + are called operators of oscillator type. Oscillator-type operators possess a number of useful properties in the case when the elementary operators a-hat are closed. It turns out that some s.a. Calogero Hamiltonians allow oscillator-type representations. We describe such Hamiltonians and find the corresponding mutually adjoint elementary operators a-hat and a-hat + . An oscillator-type representation for a given Hamiltonian is generally not unique. (paper)

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

Synchronization of an ensemble of oscillators regulated by their spatial movement.

Science.gov (United States)

Sarkar, Sumantra; Parmananda, P

2010-12-01

Synchronization for a collection of oscillators residing in a finite two dimensional plane is explored. The coupling between any two oscillators in this array is unidirectional, viz., master-slave configuration. Initially the oscillators are distributed randomly in space and their autonomous time-periods follow a Gaussian distribution. The duty cycles of these oscillators, which work under an on-off scenario, are normally distributed as well. It is realized that random hopping of oscillators is a necessary condition for observing global synchronization in this ensemble of oscillators. Global synchronization in the context of the present work is defined as the state in which all the oscillators are rendered identical. Furthermore, there exists an optimal amplitude of random hopping for which the attainment of this global synchronization is the fastest. The present work is deemed to be of relevance to the synchronization phenomena exhibited by pulse coupled oscillators such as a collection of fireflies. © 2010 American Institute of Physics.

Low-Frequency Oscillations and Transport Processes Induced by Multiscale Transverse Structures in the Polar Wind Outflow: A Three-Dimensional Simulation

Science.gov (United States)

Ganguli, Supriya B.; Gavrishchaka, Valeriy V.

1999-01-01

Multiscale transverse structures in the magnetic-field-aligned flows have been frequently observed in the auroral region by FAST and Freja satellites. A number of multiscale processes, such as broadband low-frequency oscillations and various cross-field transport effects are well correlated with these structures. To study these effects, we have used our three-dimensional multifluid model with multiscale transverse inhomogeneities in the initial velocity profile. Self-consistent-frequency mode driven by local transverse gradients in the generation of the low field-aligned ion flow and associated transport processes were simulated. Effects of particle interaction with the self-consistent time-dependent three-dimensional wave potential have been modeled using a distribution of test particles. For typical polar wind conditions it has been found that even large-scale (approximately 50 - 100 km) transverse inhomogeneities in the flow can generate low-frequency oscillations that lead to significant flow modifications, cross-field particle diffusion, and other transport effects. It has also been shown that even small-amplitude (approximately 10 - 20%) short-scale (approximately 10 km) modulations of the original large-scale flow profile significantly increases low-frequency mode generation and associated cross-field transport, not only at the local spatial scales imposed by the modulations but also on global scales. Note that this wave-induced cross-field transport is not included in any of the global numerical models of the ionosphere, ionosphere-thermosphere, or ionosphere-polar wind. The simulation results indicate that the wave-induced cross-field transport not only affects the ion outflow rates but also leads to a significant broadening of particle phase-space distribution and transverse particle diffusion.

Identical phase oscillators with global sinusoidal coupling evolve by Mobius group action.

Science.gov (United States)

Marvel, Seth A; Mirollo, Renato E; Strogatz, Steven H

2009-12-01

Systems of N identical phase oscillators with global sinusoidal coupling are known to display low-dimensional dynamics. Although this phenomenon was first observed about 20 years ago, its underlying cause has remained a puzzle. Here we expose the structure working behind the scenes of these systems by proving that the governing equations are generated by the action of the Mobius group, a three-parameter subgroup of fractional linear transformations that map the unit disk to itself. When there are no auxiliary state variables, the group action partitions the N-dimensional state space into three-dimensional invariant manifolds (the group orbits). The N-3 constants of motion associated with this foliation are the N-3 functionally independent cross ratios of the oscillator phases. No further reduction is possible, in general; numerical experiments on models of Josephson junction arrays suggest that the invariant manifolds often contain three-dimensional regions of neutrally stable chaos.

On the relation between the frequency of oscillation of a virtual cathode and injected current in one-dimensional grounded drift space

International Nuclear Information System (INIS)

Kumar, Raghwendra; Puri, R.R.; Biswas, D.

2004-01-01

The relationship between the injected current density j 0 and the dominant fundamental oscillation frequency f of a virtual cathode in a one-dimensional grounded infinite planar drift space of length L is determined numerically. If the electrons, each of mass m e and charge e, are injected with velocity v 0 , it is found that for vertical bar j 0 vertical bar >>m e v 0 3 /18π vertical bar e vertical bar L 2 , f∼√(vertical bar j 0 vertical bar) which is in contrast to the relation f∼vertical bar j 0 vertical bar reported by earlier workers

On the connection between the hydrogen atom and the harmonic oscillator: the zero-energy case

International Nuclear Information System (INIS)

Kibler, M.; Negali, T.

1983-09-01

The connection between the three-dimensional hydrogen atom and a four-dimensional harmonic oscillator obtained in previous works, from an hybridization of the infinitesimal Pauli approach to the hydrogen system with the Schwinger approach to spherical and hyperbolical angular momenta, is worked out in the case of the zero-energy point of the hydrogen atom. This leads to the equivalence of the three-dimensional hydrogen problem with a four-dimensional free-particle problem involving a constraint condition. For completeness, the latter results is also derived by using the Kustaanheimo-Stiefel transformation introduced in celestial mechanics. Finally, it is shown how the Lie algebra of SO(4,2) quite naturally arises for the whole spectrum (discrete + continuum + zero-energy point) of the three-dimensional hydrogen atom from the introduction of the constraint condition into the Lie algebra of Sp(8,R) associated to the four-dimensional harmonic oscillator

Phlebographic variants of valvular insufficiency of deep veins in varicose disease of the lower limbs

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

Replicate periodic windows in the parameter space of driven oscillators

Energy Technology Data Exchange (ETDEWEB)

Medeiros, E.S., E-mail: esm@if.usp.br [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo (Brazil); Souza, S.L.T. de [Universidade Federal de Sao Joao del-Rei, Campus Alto Paraopeba, Minas Gerais (Brazil); Medrano-T, R.O. [Departamento de Ciencias Exatas e da Terra, Universidade Federal de Sao Paulo, Diadema, Sao Paulo (Brazil); Caldas, I.L. [Instituto de Fisica, Universidade de Sao Paulo, Sao Paulo (Brazil)

2011-11-15

Highlights: > We apply a weak harmonic perturbation to control chaos in two driven oscillators. > We find replicate periodic windows in the driven oscillator parameter space. > We find that the periodic window replication is associated with the chaos control. - Abstract: In the bi-dimensional parameter space of driven oscillators, shrimp-shaped periodic windows are immersed in chaotic regions. For two of these oscillators, namely, Duffing and Josephson junction, we show that a weak harmonic perturbation replicates these periodic windows giving rise to parameter regions correspondent to periodic orbits. The new windows are composed of parameters whose periodic orbits have the same periodicity and pattern of stable and unstable periodic orbits already existent for the unperturbed oscillator. Moreover, these unstable periodic orbits are embedded in chaotic attractors in phase space regions where the new stable orbits are identified. Thus, the observed periodic window replication is an effective oscillator control process, once chaotic orbits are replaced by regular ones.

Magnetohydrodynamic waves in two-dimensional prominences embedded in coronal arcades

International Nuclear Information System (INIS)

Terradas, J.; Soler, R.; Díaz, A. J.; Oliver, R.; Ballester, J. L.

2013-01-01

Solar prominence models used so far in the analysis of MHD waves in two-dimensional structures are quite elementary. In this work, we calculate numerically magnetohydrostatic models in two-dimensional configurations under the presence of gravity. Our interest is in models that connect the magnetic field to the photosphere and include an overlying arcade. The method used here is based on a relaxation process and requires solving the time-dependent nonlinear ideal MHD equations. Once a prominence model is obtained, we investigate the properties of MHD waves superimposed on the structure. We concentrate on motions purely two-dimensional, neglecting propagation in the ignorable direction. We demonstrate how, by using different numerical tools, we can determine the period of oscillation of stable waves. We find that vertical oscillations, linked to fast MHD waves, are always stable and have periods in the 4-10 minute range. Longitudinal oscillations, related to slow magnetoacoustic-gravity waves, have longer periods in the range of 28-40 minutes. These longitudinal oscillations are strongly influenced by the gravity force and become unstable for short magnetic arcades.

Seizure Dynamics of Coupled Oscillators with Epileptor Field Model

Science.gov (United States)

Zhang, Honghui; Xiao, Pengcheng

The focus of this paper is to investigate the dynamics of seizure activities by using the Epileptor coupled model. Based on the coexistence of seizure-like event (SLE), refractory status epilepticus (RSE), depolarization block (DB), and normal state, we first study the dynamical behaviors of two coupled oscillators in different activity states with Epileptor model by linking them with slow permittivity coupling. Our research has found that when one oscillator in normal states is coupled with any oscillator in SLE, RSE or DB states, these two oscillators can both evolve into SLE states under appropriate coupling strength. And then these two SLE oscillators can perform epileptiform synchronization or epileptiform anti-synchronization. Meanwhile, SLE can be depressed when considering the fast electrical or chemical coupling in Epileptor model. Additionally, a two-dimensional reduced model is also given to show the effect of coupling number on seizures. Those results can help to understand the dynamical mechanism of the initiation, maintenance, propagation and termination of seizures in focal epilepsy.

Chemical potential of one-dimensional simple harmonic oscillators

International Nuclear Information System (INIS)

Mungan, Carl E

2009-01-01

Expressions for the chemical potential of an Einstein solid, and of ideal Fermi and Bose gases in an external one-dimensional oscillatory trap, are calculated by two different methods and are all found to share the same functional form. These derivations are easier than traditional textbook calculations for an ideal gas in an infinite three-dimensional square well. Furthermore, the results indicate some important features of chemical potential that could promote student learning in an introductory course in statistical mechanics at the undergraduate level.

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...

Breathing multichimera states in nonlocally coupled phase oscillators

Science.gov (United States)

Suda, Yusuke; Okuda, Koji

2018-04-01

Chimera states for the one-dimensional array of nonlocally coupled phase oscillators in the continuum limit are assumed to be stationary states in most studies, but a few studies report the existence of breathing chimera states. We focus on multichimera states with two coherent and incoherent regions and numerically demonstrate that breathing multichimera states, whose global order parameter oscillates temporally, can appear. Moreover, we show that the system exhibits a Hopf bifurcation from a stationary multichimera to a breathing one by the linear stability analysis for the stationary multichimera.

Quasioptical Josephson oscillator

International Nuclear Information System (INIS)

Wengler, M.J.; Pance, A.; Liu, B.

1991-01-01

This paper discusses the authors' work with large 2-dimensional arrays of Josephson junctions for submillimeter power generation. The basic design of the Quasioptical Josephson Oscillator (QJO) is presented. The reasons for each design decision are discussed. Superconducting devices have not yet been fabricated, but scale models and computer simulations have been done. A method for characterizing array rf coupling structures is described, and initial results with this method are presented. Microwave scale models of the radiation structure are built and a series of measurements are made with a network analyzer

Coupled nonlinear oscillators

Energy Technology Data Exchange (ETDEWEB)

Chandra, J; Scott, A C

1983-01-01

Topics discussed include transitions in weakly coupled nonlinear oscillators, singularly perturbed delay-differential equations, and chaos in simple laser systems. Papers are presented on truncated Navier-Stokes equations in a two-dimensional torus, on frequency locking in Josephson point contacts, and on soliton excitations in Josephson tunnel junctions. Attention is also given to the nonlinear coupling of radiation pulses to absorbing anharmonic molecular media, to aspects of interrupted coarse-graining in stimulated excitation, and to a statistical analysis of long-term dynamic irregularity in an exactly soluble quantum mechanical model.

[COMPARISON OF INTRAOPERATIVE SCLEROOBLITERATION AND ECHOSCLEROOBLITERATION EFFICIENCY OF VARICOSE DISEASES OF THE LOWER EXTREMITIES C6 CLASS IN PATIENTS BY TYPE II DIABETES MELLITUS].

Science.gov (United States)

Palamarchuk, V I; Odnorog, S I; Gvozdyak, M M; Vilgash, A M

2015-06-01

The experience of surgical treatment of 50 patients for varicose disease of lower extremities, complicated by trophic ulcers, in the presence of diabetes mellitus type II were analysed. During surgery in patients of the 1st group performed a combined phlebectomy, group 2--scleroobliteration and echoscleroobliteration. Using fleboscleroobliteration method helped reduce the frequency of early postoperative complications in (6.5 +/- 1.3) times.

Changes of serum IL-1 and sIL-2R levels after intravenous photo-coagulation in patients with varicose greater saphenous vein

International Nuclear Information System (INIS)

Han Li'na; Gu Ying; Liu Fanguang

2004-01-01

Objective: To determine the changes of serum interleukin 2 (IL-2) and soluble interleukin 2 receptor (sIL-2R) levels in patients with varicose greater saphenous vein after intravenous photocoagulation. Methods: Fifty patients with varicose greater saphenous vein were divided into two groups (mild and severe) according to their clinical symptoms. Serum IL-2 and sIL-2R levels were determined with RIA and ELISA respectively in these patients and 30 controls. Results: Serum levels of IL-2 and sIL-2R in patients of the mild group were about the same as those in the controls. In patients of the severe group, levels of IL-2 decreased and levels of sIL-2R increased significantly. After photocoagulation, the IL-2 levels dropped at first but gradually rose; the reverse was true for the sIL-2R levels. The final levels of IL-2 and sIL-2R approached those before treatment in the mild group. In the severe group, the final IL-2 levels were higher and sIL-2R levels lower than those before photocoagulation. Conclusion: Determination of serum IL-2 and sIL-2R levels revealed information about the immune status of the patients and could be applied for judgement of the treatment effect

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

Spherical anharmonic oscillator in self-similar approximation

International Nuclear Information System (INIS)

Yukalova, E.P.; Yukalov, V.I.

1992-01-01

The method of self-similar approximation is applied here for calculating the eigenvalues of the three-dimensional spherical anharmonic oscillator. The advantage of this method is in its simplicity and high accuracy. The comparison with other known analytical methods proves that this method is more simple and accurate. 25 refs

Rabi oscillations in the dissociative continuum: Rotation and alignment effects

Science.gov (United States)

Granucci, Giovanni; Magnier, Sylvie; Persico, Maurizio

2002-01-01

We have simulated a set of experiments in which Rabi oscillations are induced in bound-free and free-free transitions of a diatomic molecule. Dissociative vibrational states belonging to different electronic terms are involved. We show analytically and confirm computationally that a simple relationship exists between the one-dimensional dynamics of a molecule with fixed orientation with respect to the polarization of the radiation field and the three-dimensional dynamics of a rotating system. It is demonstrated that sufficiently short laser pulses can induce oscillations in the probabilities of two coupled electronic states, and in the yields of the respective dissociation products, as functions of the radiation intensity. As a result of molecular rotation the oscillations are damped but not washed out. The initial thermal distribution on several rotational levels has a negligible effect on the photodissociation yields and other experimentally relevant quantities. Since the molecule undergoes a strong alignment along the polarization axis of the laser field, the ejection of atoms and ions is anisotropic. We have chosen the well known diatomic ion Na2+ as a convenient example.

SEISMOLOGY OF A LARGE SOLAR CORONAL LOOP FROM EUVI/STEREO OBSERVATIONS OF ITS TRANSVERSE OSCILLATION

International Nuclear Information System (INIS)

Verwichte, E.; Van Doorsselaere, T.; Foullon, C.; Nakariakov, V. M.; Aschwanden, M. J.

2009-01-01

The first analysis of a transverse loop oscillation observed by both Solar TErrestrial RElations Observatories (STEREO) spacecraft is presented, for an event on the 2007 June 27 as seen by the Extreme Ultraviolet Imager (EUVI). The three-dimensional loop geometry is determined using a three-dimensional reconstruction with a semicircular loop model, which allows for an accurate measurement of the loop length. The plane of wave polarization is found from comparison with a simulated loop model and shows that the oscillation is a fundamental horizontally polarized fast magnetoacoustic kink mode. The oscillation is characterized using an automated method and the results from both spacecraft are found to match closely. The oscillation period is 630 ± 30 s and the damping time is 1000 ± 300 s. Also, clear intensity variations associated with the transverse loop oscillations are reported for the first time. They are shown to be caused by the effect of line-of-sight integration. The Alfven speed and coronal magnetic field derived using coronal seismology are discussed. This study shows that EUVI/STEREO observations achieve an adequate accuracy for studying long-period, large-amplitude transverse loop oscillations.

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.

[The use of labelled albumin microspheres in the study of arteriovenous shunting in varicosities of the lower limbs (author's transl)].

Science.gov (United States)

Serise, J M; Le Héron, D; Le Héron, G; Bonnet, A; Busquet, J; Basse-Cathalinat, B; Tingaud, R

1982-01-01

The greater proportion of oxygen in the blood circulating in veins of the lower limbs bought to attention the possibility of pre-capillary arteriovenous shunting. The intra-arteriel injection of Technetium labelled serum albumin microspheres enables one to quantify arteriovenous shunts greater than 25 microns. The authors made a comparative study of arterio-venous shunting by blood gases analysis and isotopic techniques in twenty patients. The results seem to deny the existence of arteriovenous shunts in the genesis of essential varicose veins in the lower limb.

Varicose Vein Stripping Under Low-Dose Spinal Anaesthesia

Directory of Open Access Journals (Sweden)

Nalan Muhammedoğlu

2014-03-01

Full Text Available Aim: Spinal anesthesia is frequently used for procedures involving the lower limbs. Compared with general anesthesia, low-dose spinal anesthesia is a cost-effective method and has advantages such as avoiding hypotension, longer duration of anesthesia and increased length of hospitalization. The aim of this trial was to compare two different low-dose bupivacaine drug regimens. Methods: Sixty unpremedicated patients were randomly allocated into two groups (n=30. There were no differences between the groups in age, weight, the American Society of Anesthesiologists (ASA physical status classification, gender, and duration of surgery. We performed spinal anesthesia at the L3-4 interspace with the patient in the lateral decubitus position. We administered 6.5 mg (group 1 and 8 mg (group 2 0.5% heavy bupivacaine into the subarachnoid space. We positioned the patient laterally to the operation side for 15 minutes, then, turned to supine position. Motor and sensory block was assessed by the Bromage scale and pinprick test. Results: There were significant differences between the two groups in duration of motor block, but no significant differences in hemodynamic response to spinal anesthesia. None of the patients had intraoperative pain. Five patients in group 1 and 2 patients in group 2 had urinary retention. Conclusion: Our observations suggest that 6.5 mg heavy bupivacaine is efficient and suitable for unilateral varicose veins stripping operation. (The Me­di­cal Bul­le­tin of Ha­se­ki 2014; 52: 25-8

Endovenous radiofrequency ablation using stent-type electrode for varicose veins: an experimental study in goats

Energy Technology Data Exchange (ETDEWEB)

Won, Je Hwan; Han, Jae Ho; Oh, Chang Kwon [Ajou University Hospital, Suwon (Korea, Republic of); Kwak, Young Lan [Yonsei University College of Medicine, Seoul (Korea, Republic of); Park, Sung Il [Ulsan University GangNeung Asan Hospital, Gangeung (Korea, Republic of)

2004-10-15

The purpose of this study was to investigate the feasibility and the optimal conditions of radiofrequency (RF) ablation by using the stent-type electrode upon the saphenous vein of goats for the endovenous treatment of varicose veins. A self-expandable nitinol stent electrode (6 mm diameter, 2 cm length, cell size; 1.3 x 2 mm) was designed to expose the distal 1 cm segment to allow for contact with the venous wall. The proximal part of the electrode was connected to the RF generator by insulated copper wires located within the stent electrode introducer. Initially, to optimize the power setting, ablation of 6 saphenous veins in 3 goats was performed with power settings of 10, 20 and 30 W. Pull back rate of the electrode was 2 and 4 cm/min for each power level, respectively. The goats were sacrificed 4-6 weeks later and histologic examinations of the saphenous veins were done. For the second part of the experiment, RF ablation of 4 saphenous veins from 2 goats was done by applying the optimal power, based upon the first examination; these procedure was performed with variable pull back rates. Again, the goats were sacrificed 1-6 weeks later and histologic examinations were done. Endovenous ablation of the goat saphenous veins at 20 W caused complete obliteration without complication. There was incomplete occlusion at 10 W, and there were vessel perforation, extravasation, and adjacent tissue injury at 30 W. In second part of the study, the complete circumferential obliteration of the vein was demonstrated at a pull back rate of 1 cm/min and 3 cm/min with the power of 20 W. The stent-type electrode may be useful in endovenous RF ablation for treatment of varicose veins. For stents with a diameter of 6 mm, the optional combination of 20 W of power with a pull back rate of 1-3 cm/min produced the most favorable results. Further study and clinical investigations are warranted.

Endovenous radiofrequency ablation using stent-type electrode for varicose veins: an experimental study in goats

International Nuclear Information System (INIS)

Won, Je Hwan; Han, Jae Ho; Oh, Chang Kwon; Kwak, Young Lan; Park, Sung Il

2004-01-01

The purpose of this study was to investigate the feasibility and the optimal conditions of radiofrequency (RF) ablation by using the stent-type electrode upon the saphenous vein of goats for the endovenous treatment of varicose veins. A self-expandable nitinol stent electrode (6 mm diameter, 2 cm length, cell size; 1.3 x 2 mm) was designed to expose the distal 1 cm segment to allow for contact with the venous wall. The proximal part of the electrode was connected to the RF generator by insulated copper wires located within the stent electrode introducer. Initially, to optimize the power setting, ablation of 6 saphenous veins in 3 goats was performed with power settings of 10, 20 and 30 W. Pull back rate of the electrode was 2 and 4 cm/min for each power level, respectively. The goats were sacrificed 4-6 weeks later and histologic examinations of the saphenous veins were done. For the second part of the experiment, RF ablation of 4 saphenous veins from 2 goats was done by applying the optimal power, based upon the first examination; these procedure was performed with variable pull back rates. Again, the goats were sacrificed 1-6 weeks later and histologic examinations were done. Endovenous ablation of the goat saphenous veins at 20 W caused complete obliteration without complication. There was incomplete occlusion at 10 W, and there were vessel perforation, extravasation, and adjacent tissue injury at 30 W. In second part of the study, the complete circumferential obliteration of the vein was demonstrated at a pull back rate of 1 cm/min and 3 cm/min with the power of 20 W. The stent-type electrode may be useful in endovenous RF ablation for treatment of varicose veins. For stents with a diameter of 6 mm, the optional combination of 20 W of power with a pull back rate of 1-3 cm/min produced the most favorable results. Further study and clinical investigations are warranted

Recurrence of superficial vein thrombosis in patients with varicose veins.

Science.gov (United States)

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.

Lie algebraic approach to the time-dependent quantum general harmonic oscillator and the bi-dimensional charged particle in time-dependent electromagnetic fields

International Nuclear Information System (INIS)

Ibarra-Sierra, V.G.; Sandoval-Santana, J.C.; Cardoso, J.L.; Kunold, A.

2015-01-01

We discuss the one-dimensional, time-dependent general quadratic Hamiltonian and the bi-dimensional charged particle in time-dependent electromagnetic fields through the Lie algebraic approach. Such method consists in finding a set of generators that form a closed Lie algebra in terms of which it is possible to express a quantum Hamiltonian and therefore the evolution operator. The evolution operator is then the starting point to obtain the propagator as well as the explicit form of the Heisenberg picture position and momentum operators. First, the set of generators forming a closed Lie algebra is identified for the general quadratic Hamiltonian. This algebra is later extended to study the Hamiltonian of a charged particle in electromagnetic fields exploiting the similarities between the terms of these two Hamiltonians. These results are applied to the solution of five different examples: the linear potential which is used to introduce the Lie algebraic method, a radio frequency ion trap, a Kanai–Caldirola-like forced harmonic oscillator, a charged particle in a time dependent magnetic field, and a charged particle in constant magnetic field and oscillating electric field. In particular we present exact analytical expressions that are fitting for the study of a rotating quadrupole field ion trap and magneto-transport in two-dimensional semiconductor heterostructures illuminated by microwave radiation. In these examples we show that this powerful method is suitable to treat quadratic Hamiltonians with time dependent coefficients quite efficiently yielding closed analytical expressions for the propagator and the Heisenberg picture position and momentum operators. -- Highlights: •We deal with the general quadratic Hamiltonian and a particle in electromagnetic fields. •The evolution operator is worked out through the Lie algebraic approach. •We also obtain the propagator and Heisenberg picture position and momentum operators. •Analytical expressions for a

Lie algebraic approach to the time-dependent quantum general harmonic oscillator and the bi-dimensional charged particle in time-dependent electromagnetic fields

Energy Technology Data Exchange (ETDEWEB)

Ibarra-Sierra, V.G.; Sandoval-Santana, J.C. [Departamento de Física, Universidad Autónoma Metropolitana Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 México D.F. (Mexico); Cardoso, J.L. [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico); Kunold, A., E-mail: akb@correo.azc.uam.mx [Área de Física Teórica y Materia Condensada, Universidad Autónoma Metropolitana Azcapotzalco, Av. San Pablo 180, Col. Reynosa-Tamaulipas, Azcapotzalco, 02200 México D.F. (Mexico)

2015-11-15

We discuss the one-dimensional, time-dependent general quadratic Hamiltonian and the bi-dimensional charged particle in time-dependent electromagnetic fields through the Lie algebraic approach. Such method consists in finding a set of generators that form a closed Lie algebra in terms of which it is possible to express a quantum Hamiltonian and therefore the evolution operator. The evolution operator is then the starting point to obtain the propagator as well as the explicit form of the Heisenberg picture position and momentum operators. First, the set of generators forming a closed Lie algebra is identified for the general quadratic Hamiltonian. This algebra is later extended to study the Hamiltonian of a charged particle in electromagnetic fields exploiting the similarities between the terms of these two Hamiltonians. These results are applied to the solution of five different examples: the linear potential which is used to introduce the Lie algebraic method, a radio frequency ion trap, a Kanai–Caldirola-like forced harmonic oscillator, a charged particle in a time dependent magnetic field, and a charged particle in constant magnetic field and oscillating electric field. In particular we present exact analytical expressions that are fitting for the study of a rotating quadrupole field ion trap and magneto-transport in two-dimensional semiconductor heterostructures illuminated by microwave radiation. In these examples we show that this powerful method is suitable to treat quadratic Hamiltonians with time dependent coefficients quite efficiently yielding closed analytical expressions for the propagator and the Heisenberg picture position and momentum operators. -- Highlights: •We deal with the general quadratic Hamiltonian and a particle in electromagnetic fields. •The evolution operator is worked out through the Lie algebraic approach. •We also obtain the propagator and Heisenberg picture position and momentum operators. •Analytical expressions for a

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

Absolute and convective instability of a liquid sheet with transverse temperature gradient

International Nuclear Information System (INIS)

Fu, Qing-Fei; Yang, Li-Jun; Tong, Ming-Xi; Wang, Chen

2013-01-01

Highlights: • The spatial–temporal instability of a liquid sheet with thermal effects was studied. • The flow can transit to absolutely unstable with certain flow parameters. • The effects of non-dimensional parameters on the transition were studied. -- Abstract: The spatial–temporal instability behavior of a viscous liquid sheet with temperature difference between the two surfaces was investigated theoretically. The practical situation motivating this investigation is liquid sheet heated by ambient gas, usually encountered in industrial heat transfer and liquid propellant rocket engines. The existing dispersion relation was used, to explore the spatial–temporal instability of viscous liquid sheets with a nonuniform temperature profile, by setting both the wave number and frequency complex. A parametric study was performed in both sinuous and varicose modes to test the influence of dimensionless numbers on the transition between absolute and convective instability of the flow. For a small value of liquid Weber number, or a great value of gas-to-liquid density ratio, the flow was found to be absolutely unstable. The absolute instability was enhanced by increasing the liquid viscosity. It was found that variation of the Marangoni number hardly influenced the absolute instability of the sinuous mode of oscillations; however it slightly affected the absolute instability in the varicose mode

Double linearization theory applied to three-dimensional cascades oscillating under supersonic axial flow condition. Choonsoku jikuryu sokudo de sadosuru sanjigen shindo yokuretsu no niju senkei riron ni yoru hiteijo kukiryoku kaiseki

Energy Technology Data Exchange (ETDEWEB)

Toshimitsu, K; Nanba, M [Kgushu University, Fukuoka (Japan). Faculty of Engineering; Iwai, S [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)

1993-11-25

In order to examine the aerodynamic characteristics of a supersonic axial flow turbofan realizing flight of Mach number of 2-5, the double linearization theory was applied to a three dimensional oscillation cascade accompanying a steady load in a supersonic axial flow condition and unsteady pneumatic force and aerodynamic unstability of oscillation were studied. Moreover, the values based on the strip theory and the three-dimensional theory were comparatively evaluated. Fundamental assumptions were such that the order of steady and unsteady perturbation satisfies the holding condition of the double linearization thory in a supersonic-and equi-entropy flow of non-viscous perfect gas. The numerical calculation assumed parabolic distributions of camber and thickness in the blade shape. As a result, the strip theory prediction agreed well with the value given by the three-dimensional theory in the steady blade-plane pressure difference and in the work of an unsteady pneumatic force, showing its validity. Among the steady load components of angle of attack, camber and thickness, the component of camber whose absolute value is large has the strongest effect on the total work. The distribution reduced in the angle of attack and camber from hub toward tip gives a large and stable flutter margin. 5 refs., 13 figs., 2 tabs.

Investigation of low-frequency-oscillating water flow in metal foam with 10 pores per inch

Science.gov (United States)

Bağcı, Ö.; Arbak, A.; De Paepe, M.; Dukhan, N.

2018-01-01

In this study, oscillating water flow in metal foam with open cells is investigated experimentally. The metal foam sample has a porosity of 88% and 10 pores. The water was oscillated in the test section with three frequencies between 0.116 Hz and 0.348 Hz, which are considered low for water oscillation, and three flow displacements ranging between 74.35 mm and 111.53 mm. The combinations of frequencies of displacements were studied for their impacts of dimensional and non-dimensional pressure loss quantities. To this purpose, friction factor was correlated as a function of kinetic Reynolds number. The same metal foam sample was studied by exposing it to steady-state water flow to investigate its permeability and drag coefficient in low-velocity flow regimes. The friction factor distribution for oscillating flow was found to be over that found for steady state. The outcomes of the study are important for studying heat transfer under the same flow conditions.

A quantum mechanical model of Rabi oscillations between two interacting harmonic oscillator modes and the interconversion of modes in a Penning trap

International Nuclear Information System (INIS)

Kretzschmar, Martin

1999-01-01

When a Penning trap is operated with an additional quadrupole driving field with a frequency that equals a suitable combination (sum or difference) of the frequencies of the fundamental modes of motion (modified cyclotron, magnetron and axial frequency), then a periodic conversion of the participating modes into each other is observed, strongly resembling the Rabi oscillations in a 2-level atom driven by a laser field tuned to the transition frequency. This investigation attempts to understand on a fundamental level how and why the motion of a classical particle in a macroscopic apparatus can be truely analogous to the oscillations of states of quantum mechanical 2-level systems (2-level atom or magnetic resonance). Ion motion in a Penning trap with an additional quadrupole driving field is described in a quantum mechanical frame work. The Heisenberg equations of motion for the creation and annihilation operators of the interacting oscillators have been explicitly solved, the time development operator of the Schroedinger picture has been determined. The driving field provides for two types of intermode interaction: Type I preserves the total number of excitation quanta present in the two interacting modes, the system oscillates between the modes with a frequency corresponding to the Rabi frequency in two-level systems. Type II preserves the difference of the numbers of excitation quanta present in the two interacting modes, it causes the ion motion to become unbounded. The two types of interaction are associated in a natural way with a SU(2) and a SU(1,1) Lie algebra. The three generators of these algebras form a vector operator that we denote as the Bloch vector operator. The Hilbert space decomposes in a natural way into invariant subspaces, finite dimensional in the case of type I interaction (SU(2)-algebra) and infinite dimensional in the case of type II interaction (SU(1,1)-algebra). The physics of the 2-level atom in the laser field can be described in the 2

Flame oscillations in tubes with nonslip at the walls

Energy Technology Data Exchange (ETDEWEB)

Akkerman, V' yacheslav; Bychkov, Vitaly; Petchenko, Arkady [Institute of Physics, Umeaa University, SE-901 87 Umeaa (Sweden); Eriksson, Lars-Erik [Department of Applied Mechanics, Chalmers University of Technology, 412 96 Goeteborg (Sweden)

2006-06-15

A laminar premixed flame front propagating in a two-dimensional tube is considered with nonslip at the walls and with both ends open. The problem of flame propagation is solved using direct numerical simulations of the complete set of hydrodynamic equations including thermal conduction, diffusion, viscosity, and chemical kinetics. As a result, it is shown that flame interaction with the walls leads to the oscillating regime of burning. The oscillations involve variations of the curved flame shape and the velocity of flame propagation. The oscillation parameters depend on the characteristic tube width, which controls the Reynolds number of the flow. In narrow tubes the oscillations are rather weak, while in wider tubes they become stronger with well-pronounced nonlinear effects. The period of oscillations increases for wider tubes, while the average flame length scaled by the tube diameter decreases only slightly with increasing tube width. The average flame length calculated in the present work is in agreement with that obtained in the experiments. Numerical results reduce the gap between the theory of turbulent flames and the experiments on turbulent combustion in tubes. (author)

Quantum oscillations in nodal line systems

Science.gov (United States)

Yang, Hui; Moessner, Roderich; Lim, Lih-King

2018-04-01

We study signatures of magnetic quantum oscillations in three-dimensional nodal line semimetals at zero temperature. The extended nature of the degenerate bands can result in a Fermi surface geometry with topological genus one, as well as a Fermi surface of electron and hole pockets encapsulating the nodal line. Moreover, the underlying two-band model to describe a nodal line is not unique, in that there are two classes of Hamiltonian with distinct band topology giving rise to the same Fermi-surface geometry. After identifying the extremal cyclotron orbits in various magnetic field directions, we study their concomitant Landau levels and resulting quantum oscillation signatures. By Landau-fan-diagram analyses, we extract the nontrivial π Berry phase signature for extremal orbits linking the nodal line.

Quantum oscillation evidence for a topological semimetal phase in ZrSnTe

Science.gov (United States)

Hu, Jin; Zhu, Yanglin; Gui, Xin; Graf, David; Tang, Zhijie; Xie, Weiwei; Mao, Zhiqiang

2018-04-01

The layered WHM-type (W =Zr /Hf /La , H =Si /Ge /Sn /Sb , M =S /Se /Te ) materials represent a large family of topological semimetals, which provides an excellent platform to study the evolution of topological semimetal state with the fine tuning of spin-orbit coupling and structural dimensionality for various combinations of W , H , and M elements. In this work, through high field de Haas-van Alphen (dHvA) quantum oscillation studies, we have found evidence for the predicted topological nontrivial bands in ZrSnTe. Furthermore, from the angular dependence of quantum oscillation frequency, we have revealed the three-dimensional Fermi surface topologies of this layered material owing to strong interlayer coupling.

Phase reduction and synchronization of a network of coupled dynamical elements exhibiting collective oscillations

Science.gov (United States)

Nakao, Hiroya; Yasui, Sho; Ota, Masashi; Arai, Kensuke; Kawamura, Yoji

2018-04-01

A general phase reduction method for a network of coupled dynamical elements exhibiting collective oscillations, which is applicable to arbitrary networks of heterogeneous dynamical elements, is developed. A set of coupled adjoint equations for phase sensitivity functions, which characterize the phase response of the collective oscillation to small perturbations applied to individual elements, is derived. Using the phase sensitivity functions, collective oscillation of the network under weak perturbation can be described approximately by a one-dimensional phase equation. As an example, mutual synchronization between a pair of collectively oscillating networks of excitable and oscillatory FitzHugh-Nagumo elements with random coupling is studied.

Crypto-harmonic oscillator in higher dimensions: classical and quantum aspects

International Nuclear Information System (INIS)

Ghosh, Subir; Majhi, Bibhas Ranjan

2008-01-01

We study complexified harmonic oscillator models in two and three dimensions. Our work is a generalization of the work of Smilga (2007 Preprint 0706.4064 (J. Phys. A: Math. Theor. at press)) who initiated the study of these Crypto-gauge invariant models that can be related to PT-symmetric models. We show that rotational symmetry in higher spatial dimensions naturally introduces more constraints (in contrast to Smilga (2007 Preprint 0706.4064 (J. Phys. A: Math. Theor. at press)) where one deals with a single constraint) with a much richer constraint structure. Some common as well as distinct features in the study of the same Crypto-oscillator in different dimensions are revealed. We also quantize the two dimensional Crypto-oscillator

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 ...

The determination of the Dirac density matrix of the d-dimensional harmonic oscillator for an arbitrary number of closed shells

International Nuclear Information System (INIS)

Howard, I.A.; March, N.H.; Nieto, L.M.

2002-01-01

In 1959, March and Young (Nucl. Phys. 12 237) rewrote the equation of motion for the Dirac density matrix γ(x, x 0 ) in terms of sum and difference variables. Here, γ(r-bar, r-bar 0 ) for the d-dimensional isotropic harmonic oscillator for an arbitrary number of closed shells is shown to satisfy, using the variables vertical bar r-bar + r-bar 0 vertical bar/2 and vertical bar r-bar - r-bar 0 vertical bar/2, a generalized partial differential equation embracing the March-Young equation for d=1. As applications, we take in turn the cases d=1, 2, 3 and 4, and obtain both the density matrix γ (r-bar, r-bar 0 ) and the diagonal density ρ(r)=γ(r-bar, r-bar 0 ) vertical bar r-bar 0 =r-bar, this diagonal element already being known to satisfy a third-order linear homogeneous differential equation for d=1 through 3. Some comments are finally made on the d-dimensional kinetic energy density, which is important for first-principles density functional theory in allowing one to bypass one-particle Schroedinger equations (the so-called Slater-Kohn-Sham equations). (author)

Three dimensional nuclear magnetic resonance spectroscopic imaging of sodium ions using stochastic excitation and oscillating gradients

International Nuclear Information System (INIS)

Frederick, B.deB.

1994-12-01

Nuclear magnetic resonance (NMR) spectroscopic imaging of 23 Na holds promise as a non-invasive method of mapping Na + distributions, and for differentiating pools of Na + ions in biological tissues. However, due to NMR relaxation properties of 23 Na in vivo, a large fraction of Na + is not visible with conventional NMR imaging methods. An alternate imaging method, based on stochastic excitation and oscillating gradients, has been developed which is well adapted to measuring nuclei with short T 2 . Contemporary NMR imaging techniques have dead times of up to several hundred microseconds between excitation and sampling, comparable to the shortest in vivo 23 Na T 2 values, causing significant signal loss. An imaging strategy based on stochastic excitation has been developed which greatly reduces experiment dead time by reducing peak radiofrequency (RF) excitation power and using a novel RF circuit to speed probe recovery. Continuously oscillating gradients are used to eliminate transient eddy currents. Stochastic 1 H and 23 Na spectroscopic imaging experiments have been performed on a small animal system with dead times as low as 25μs, permitting spectroscopic imaging with 100% visibility in vivo. As an additional benefit, the encoding time for a 32x32x32 spectroscopic image is under 30 seconds. The development and analysis of stochastic NMR imaging has been hampered by limitations of the existing phase demodulation reconstruction technique. Three dimensional imaging was impractical due to reconstruction time, and design and analysis of proposed experiments was limited by the mathematical intractability of the reconstruction method. A new reconstruction method for stochastic NMR based on Fourier interpolation has been formulated combining the advantage of a several hundredfold reduction in reconstruction time with a straightforward mathematical form

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)

Phase-matching-free parametric oscillators based on two dimensional semiconductors

OpenAIRE

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...

Four-dimensional symmetry from a broad viewpoint. II Invariant distribution of quantized field oscillators and questions on infinities

Science.gov (United States)

Hsu, J. P.

1983-01-01

The foundation of the quantum field theory is changed by introducing a new universal probability principle into field operators: one single inherent and invariant probability distribution P(/k/) is postulated for boson and fermion field oscillators. This can be accomplished only when one treats the four-dimensional symmetry from a broad viewpoint. Special relativity is too restrictive to allow such a universal probability principle. A radical length, R, appears in physics through the probability distribution P(/k/). The force between two point particles vanishes when their relative distance tends to zero. This appears to be a general property for all forces and resembles the property of asymptotic freedom. The usual infinities in vacuum fluctuations and in local interactions, however complicated they may be, are all removed from quantum field theories. In appendix A a simple finite and unitary theory of unified electroweak interactions is discussed without assuming Higgs scalar bosons.

Ergodic time-reversible chaos for Gibbs' canonical oscillator

International Nuclear Information System (INIS)

Hoover, William Graham; Sprott, Julien Clinton; Patra, Puneet Kumar

2015-01-01

Nosé's pioneering 1984 work inspired a variety of time-reversible deterministic thermostats. Though several groups have developed successful doubly-thermostated models, single-thermostat models have failed to generate Gibbs' canonical distribution for the one-dimensional harmonic oscillator. A 2001 doubly-thermostated model, claimed to be ergodic, has a singly-thermostated version. Though neither of these models is ergodic this work has suggested a successful route toward singly-thermostated ergodicity. We illustrate both ergodicity and its lack for these models using phase-space cross sections and Lyapunov instability as diagnostic tools. - Highlights: • We develop cross-section and Lyapunov methods for diagnosing ergodicity. • We apply these methods to several thermostatted-oscillator problems. • We demonstrate the nonergodicity of previous work. • We find a novel family of ergodic thermostatted-oscillator problems.

Quantum infinite square well with an oscillating wall

International Nuclear Information System (INIS)

Glasser, M.L.; Mateo, J.; Negro, J.; Nieto, L.M.

2009-01-01

A linear matrix equation is considered for determining the time dependent wave function for a particle in a one-dimensional infinite square well having one moving wall. By a truncation approximation, whose validity is checked in the exactly solvable case of a linearly contracting wall, we examine the cases of a simple harmonically oscillating wall and a non-harmonically oscillating wall for which the defining parameters can be varied. For the latter case, we examine in closer detail the dependence on the frequency changes, and we find three regimes: an adiabatic behabiour for low frequencies, a periodic one for high frequencies, and a chaotic behaviour for an intermediate range of frequencies.

Impact of Laser Fiber Design on Outcome of Endovenous Ablation of Lower-Extremity Varicose Veins: Results from a Single Practice

International Nuclear Information System (INIS)

Prince, Ethan A.; Soares, Gregory M.; Silva, MaryLou; Taner, Anil; Ahn, SunHo; Dubel, Gregory J.; Jay, Bryan S.

2011-01-01

The design of laser fibers used for endovenous laser ablation (EVLA) in the management of lower-extremity varicose vein disease may affect treatment success. The purpose of this investigation is to report our experience using the gold-tip NeverTouch VenaCure laser fiber (AngioDynamics, Queensbury, NY) and to compare that to our experience with standard bare-tip fibers. A retrospective chart review of 363 consecutive EVLA treatments using the gold-tip laser fiber was performed. Demographic data including patient age, sex, history of previous varicose vein stripping, vein identity, laterality, treatment length, total applied energy in joules (J), use of adjuvant sclerotherapy and ambulatory phlebectomy, treatment-related complications, and treatment failure, which was defined as recanalization of any portion of the treated vein during follow-up as assessed by duplex ultrasound examination―were entered into a spreadsheet. These data were compared with a control group of 471 EVLA treatments performed with a standard bare-tip laser fiber. Data were analyzed using independent-samples Student’s t test, chi-square test, and multivariate analysis. Demographic data were similar between the two groups. Treatments with the gold-tip fiber had a failure rate of 11.1%, whereas treatment with a bare-tip fiber had a failure rate of 2.3% during a similar follow-up period. This difference was highly statistically significant (p < 0.0001). Multivariate analysis showed fiber type as the most significant factor associated with treatment failure. We conclude that laser fiber design has a significant effect on treatment success in the performance of EVLA.

Is radiofrequency ablation of varicose veins a valuable option? A systematic review of the literature with a cost analysis.

Science.gov (United States)

Poder, Thomas G; Fisette, Jean-François; Bédard, Suzanne K; Despatis, Marc-Antoine

2018-04-01

Since the 1990s, new techniques for the treatment of varicose veins have emerged, including radiofrequency ablation (RFA) and laser treatment. We performed a study to compare the safety, efficacy and outcomes of RFA compared to those of open surgery and laser ablation for the treatment of varicose veins. We also carried out a cost analysis of RFA compared to open surgery to assess whether RFA could help free up operating room time by being performed in an outpatient context. We conducted a systematic literature review (publication date May 2010-September 2013 for articles in English, January 1991-September 2013 for those in French). We used several checklists to measure the quality of the studies. We also collected data on costing. The literature search identified 924 publications, of which 38 were retained for analysis: 15 literature reviews, 1 good-practice guideline and 22 new primary studies. The overall level of evidence was low to moderate owing to the limited sample sizes, lack of information on patient characteristics and lack of standardization of the outcome measures. However, the results obtained are consistent from study to study. In the short and medium term, RFA is considered as effective as open surgery or laser treatment (moderate level of evidence) and presents fewer major and minor complications than open surgery (low level of evidence). Radiofrequency ablation can be performed on an outpatient basis. We calculated that RFA would be about $110-$220 more expensive per patient than open surgery. Radiofrequency ablation is a valuable alternative to open surgery and would free up operating room time in a context of low accessibility.

Is radiofrequency ablation of varicose veins a valuable option? A systematic review of the literature with a cost analysis

Science.gov (United States)

Fisette, Jean-François; Bédard, Suzanne K.; Despatis, Marc-Antoine

2018-01-01

Background Since the 1990s, new techniques for the treatment of varicose veins have emerged, including radiofrequency ablation (RFA) and laser treatment. We performed a study to compare the safety, efficacy and outcomes of RFA compared to those of open surgery and laser ablation for the treatment of varicose veins. We also carried out a cost analysis of RFA compared to open surgery to assess whether RFA could help free up operating room time by being performed in an outpatient context. Methods We conducted a systematic literature review (publication date May 2010–September 2013 for articles in English, January 1991–September 2013 for those in French). We used several checklists to measure the quality of the studies. We also collected data on costing. Results The literature search identified 924 publications, of which 38 were retained for analysis: 15 literature reviews, 1 good-practice guideline and 22 new primary studies. The overall level of evidence was low to moderate owing to the limited sample sizes, lack of information on patient characteristics and lack of standardization of the outcome measures. However, the results obtained are consistent from study to study. In the short and medium term, RFA is considered as effective as open surgery or laser treatment (moderate level of evidence) and presents fewer major and minor complications than open surgery (low level of evidence). Radiofrequency ablation can be performed on an outpatient basis. We calculated that RFA would be about $110–$220 more expensive per patient than open surgery. Conclusion Radiofrequency ablation is a valuable alternative to open surgery and would free up operating room time in a context of low accessibility. PMID:29582749

Endovenous treatment of primary varicose veins: an effective and safe therapeutic alternative to stripping?

International Nuclear Information System (INIS)

Kluner, C.; Fischer, T.; Filimonow, S.; Hamm, B.; Kroencke, T.

2005-01-01

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.)

Energy localization in the phi4 oscillator chain.

Science.gov (United States)

Ponno, A; Ruggiero, J; Drigo, E; De Luca, J

2006-05-01

We study energy localization in a finite one-dimensional phi(4) oscillator chain with initial energy in a single oscillator of the chain. We numerically calculate the effective number of degrees of freedom sharing the energy on the lattice as a function of time. We find that for energies smaller than a critical value, energy equipartition among the oscillators is reached in a relatively short time. On the other hand, above the critical energy, a decreasing number of particles sharing the energy is observed. We give an estimate of the effective number of degrees of freedom as a function of the energy. Our results suggest that localization is due to the appearance, above threshold, of a breather-like structure. Analytic arguments are given, based on the averaging theory and the analysis of a discrete nonlinear Schrödinger equation approximating the dynamics, to support and explain the numerical results.

The one-dimensional Gross-Pitaevskii equation and its some excitation states

Energy Technology Data Exchange (ETDEWEB)

Prayitno, T. B., E-mail: trunk-002@yahoo.com [Physics Department, Faculty of Mathematics and Natural Science, Universitas Negeri Jakarta, Jl. Pemuda Rawamangun no. 10, Jakarta, 13220 (Indonesia)

2015-04-16

We have derived some excitation states of the one-dimensional Gross-Pitaevskii equation coupled by the gravitational potential. The methods that we have used here are taken by pursuing the recent work of Kivshar et. al. by considering the equation as a macroscopic quantum oscillator. To obtain the states, we have made the appropriate transformation to reduce the three-dimensional Gross-Pitaevskii equation into the one-dimensional Gross-Pitaevskii equation and applying the time-independent perturbation theory in the general solution of the one-dimensional Gross-Pitaevskii equation as a linear superposition of the normalized eigenfunctions of the Schrödinger equation for the harmonic oscillator potential. Moreover, we also impose the condition by assuming that some terms in the equation should be so small in order to preserve the use of the perturbation method.

Changes of plasma IL-6 and TNF-α levels during peri-operative period in patients undergoing laser photo-coagulation of greater saphenous varicosities

International Nuclear Information System (INIS)

Wang Taihan; Wang Chunxi

2005-01-01

Objective: To investigate the plasma levels of IL-6 and TNF-α during peri-operative period in patients undergoing laser photocoagulation of greater saphenous varicosities. Methods: Plasma IL-6 and TNF-α levels were determined with RIA before operation and 1, 3, 7, 14 days post-operatively in 110 patients with greater saphenous vein varicosity undergoing different forms of treatment (intravascular laser photo-coagulation 43, photo-coagulation combined with venous valve repair 35, high ligation and segmental stripping 32). Skin trophic disturbances were present in 56 of the 110 patients. Plasma IL-6 and TNF-α levels were also measured in 33 controls. Results: The plasma IL-6 and TNF-α levels in patients with skin trophic disturbances were significantly higher than those in controls (P<0.01), while levels in patients without skin lesions were not much changed. The plasma IL-6 and TNF-α levels were increased at first and dropped later to approaching pre-operative value by d14 in all the 110 patients after operation, however, the amount of increase was least and the normalization was also soonest in the simple photo-coagulation group, the reverse was true for the conventional operation group. Conclusion: Laser photo-coagulation is least stressful among the three types of operation and magnitude of changes of plasma IL-6 and TNF-α levels correctly reflects the intensity of stress. (authors)

A memristor-based third-order oscillator: beyond oscillation

KAUST Repository

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

KAUST Repository

Talukdar, Abdul Hafiz Ibne; Radwan, Ahmed G.; Salama, Khaled N.

2012-01-01

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.

Remark on the solution of the Schroedinger equation for anharmonic oscillators via the Feynman path integral

International Nuclear Information System (INIS)

Rezende, J.

1983-01-01

We give a simple proof of Feynman's formula for the Green's function of the n-dimensional harmonic oscillator valid for every time t with Im t<=0. As a consequence the Schroedinger equation for the anharmonic oscillator is integrated and expressed by the Feynman path integral on Hilbert space. (orig.)

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.

Chaotic weak chimeras and their persistence in coupled populations of phase oscillators

International Nuclear Information System (INIS)

Bick, Christian; Ashwin, Peter

2016-01-01

Nontrivial collective behavior may emerge from the interactive dynamics of many oscillatory units. Chimera states are chaotic patterns of spatially localized coherent and incoherent oscillations. The recently-introduced notion of a weak chimera gives a rigorously testable characterization of chimera states for finite-dimensional phase oscillator networks. In this paper we give some persistence results for dynamically invariant sets under perturbations and apply them to coupled populations of phase oscillators with generalized coupling. In contrast to the weak chimeras with nonpositive maximal Lyapunov exponents constructed so far, we show that weak chimeras that are chaotic can exist in the limit of vanishing coupling between coupled populations of phase oscillators. We present numerical evidence that positive Lyapunov exponents can persist for a positive measure set of this inter-population coupling strength. (paper)

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)

Modeling of Coupled Chaotic Oscillators

International Nuclear Information System (INIS)

Lai, Y.; Grebogi, C.

1999-01-01

Chaotic dynamics may impose severe limits to deterministic modeling by dynamical equations of natural systems. We give theoretical argument that severe modeling difficulties may occur for high-dimensional chaotic systems in the sense that no model is able to produce reasonably long solutions that are realized by nature. We make these ideas concrete by investigating systems of coupled chaotic oscillators. They arise in many situations of physical and biological interests, and they also arise from discretization of nonlinear partial differential equations. copyright 1999 The American Physical Society

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.

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 ...

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

Self-sustained oscillations in the divertor plasma

International Nuclear Information System (INIS)

Krasheninnikov, S.I.; Kukushkin, A.S.; Pistunovich, V.I.; Pozharov, V.A.

1985-01-01

A simple analytical model of the edge plasma with high recycling, which relays on the presence of a small parameter - the ratio of the particle flows crossing the magnetic field to those impinging onto the divertor target, is proposed. A concept of the one-dimensional steady state (OSS) is introduced as the zero approximation in the small parameter. The mean number density N-tilde of the particles - ions plus neutrals - in the magnetic flux tube is choosen as the most representative and convenient parameter of the problem. The OSS are shown to be ambiguous in some N-tilde range for sufficiently high values of the energy flow entering the scrape-off layer from the bulk plasma. An equation, that describes a quasi-steady variations in OSS, is derived and a mechanism of exciting the self-sustained oscillations is developed. Results of simulation of the edge plasma oscillations are found to be in a good agreement with this mechanism, which could be responsible for the H-mode oscillations observed in the divertor experiments

Predicting charmonium and bottomonium spectra with a quark harmonic oscillator

Science.gov (United States)

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.

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 ...

The su(1, 1) dynamical algebra from the Schroedinger ladder operators for N-dimensional systems: hydrogen atom, Mie-type potential, harmonic oscillator and pseudo-harmonic oscillator

International Nuclear Information System (INIS)

Martinez, D; Flores-Urbina, J C; Mota, R D; Granados, V D

2010-01-01

We apply the Schroedinger factorization to construct the ladder operators for the hydrogen atom, Mie-type potential, harmonic oscillator and pseudo-harmonic oscillator in arbitrary dimensions. By generalizing these operators we show that the dynamical algebra for these problems is the su(1, 1) Lie algebra.

MR venography using the 3D-MEDIC (multi echo data imaging combination) sequence for lower extremities

International Nuclear Information System (INIS)

Kitagawa, Hisashi; Kishi, Takayuki; Saito, Ryo; Shohji, Tomokazu; Noguchi, Keiji; Sunohara, Nobuo

2008-01-01

It is possible to diagnose varicose vein from medical history and physical examinations including inspection and palpation. Non-contrast enhanced MRV (magnetic resonance venography) is becoming popular because it can be easily performed without being affected by the radiographer's skill. We thought that the use of MEDIC (multi echo data imaging combination) would enable us to delineate varicose veins within a short acquisition time and without need for synchronization or contrast enhancement. We used the SIEMENS MAGNETOM Avanto 1.5-Tesla unit to acquire images. Our subjects were five healthy volunteers and five patients with varicose vein. The signal strength of deep veins and muscles were measured. The SNR (signal-to-nose ratio) of deep veins and the CNR (contrast-to-noise ratio) between deep veins and muscles were also measured. Flip angle, fat suppression methods, MTC (magnetic transfer contrast) pulse, and combined echo. Using the optimum image acquisition protocol following our preliminary study with varicose vein patients, the ability of the 3D-MEDIC method to delineate varicose veins was compared with that of the electrocardiogram (ECG)-synchronized two-dimensional time of flight (2D-TOF) method. We found that the following settings would enable us to acquire images from a wide range=coronal, within short acquisition time and needless ECG-triggering. Flip angle=20 degrees, fat suppression method=water excitation, MTC pulse=ON, combined echo=2. 3D-MEDIC was better than the 2D-TOF method in delineating the varicose vein itself and the connection between the varicose vein and deep veins. It is expected that 3D-MEDIC may be useful in the clinical diagnosis of varicose veins. (author)

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.

Dimensional reduction in Bose-Einstein-condensed alkali-metal vapors

International Nuclear Information System (INIS)

Salasnich, L.; Reatto, L.; Parola, A.

2004-01-01

We investigate the effects of dimensional reduction in atomic Bose-Einstein condensates (BECs) induced by a strong harmonic confinement in the cylindric radial direction or in the cylindric axial direction. The former case corresponds to a transition from three dimensions (3D) to 1D in cigar-shaped BECs, while the latter case corresponds to a transition from 3D to 2D in disk-shaped BECs. We analyze the first sound velocity in axially homogeneous cigar-shaped BECs and in radially homogeneous disk-shaped BECs. We consider also the dimensional reduction in a BEC confined by a harmonic potential both in the radial direction and in the axial direction. By using a variational approach, we calculate monopole and quadrupole collective oscillations of the BEC. We find that the frequencies of these collective oscillations are related to the dimensionality and to the repulsive or attractive interatomic interaction

Spiral wave chimera states in large populations of coupled chemical oscillators

Science.gov (United States)

Totz, Jan Frederik; Rode, Julian; Tinsley, Mark R.; Showalter, Kenneth; Engel, Harald

2018-03-01

The coexistence of coherent and incoherent dynamics in a population of identically coupled oscillators is known as a chimera state1,2. Discovered in 20023, this counterintuitive dynamical behaviour has inspired extensive theoretical and experimental activity4-15. The spiral wave chimera is a particularly remarkable chimera state, in which an ordered spiral wave rotates around a core consisting of asynchronous oscillators. Spiral wave chimeras were theoretically predicted in 200416 and numerically studied in a variety of systems17-23. Here, we report their experimental verification using large populations of nonlocally coupled Belousov-Zhabotinsky chemical oscillators10,18 in a two-dimensional array. We characterize previously unreported spatiotemporal dynamics, including erratic motion of the asynchronous spiral core, growth and splitting of the cores, as well as the transition from the chimera state to disordered behaviour. Spiral wave chimeras are likely to occur in other systems with long-range interactions, such as cortical tissues24, cilia carpets25, SQUID metamaterials26 and arrays of optomechanical oscillators9.

Breathing oscillations in enlarged cylindrical-anode-layer Hall plasma accelerator

Energy Technology Data Exchange (ETDEWEB)

Geng, S. F.; Wang, C. X. [Southwestern Institute of Physics, Chengdu 610041 (China); Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Tang, D. L.; Qiu, X. M. [Southwestern Institute of Physics, Chengdu 610041 (China); Fu, R. K. Y. [Plasma Technology Limited, Festival Walk Tower, Tat Chee Avenue, Kowloon, Hong Kong (China); Chu, Paul K. [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2013-05-28

Breathing oscillations in the discharge of an enlarged cylindrical-anode-layer Hall plasma accelerator are investigated by three-dimensional particle-in-cell (PIC) simulation. Different from the traditional breathing mode in a circular Hall plasma accelerator, the bulk plasma oscillation here is trigged by the potential barrier generated by the concentrated ion beam and substantial enough to compete with the anode voltage. The electric field near the anode is suppressed by the potential barrier thereby decreasing the electron density by {approx}36%. The discharge is restored to the normal level after the concentrated beam explodes and then it completes one cycle of electro-driven breathing oscillation. The breathing mode identified by the PIC simulation has a frequency range of {approx}156 kHz-{approx}250 kHz and does not vary monotonically with the discharge voltage.

Baryon acoustic oscillation intensity mapping of dark energy.

Science.gov (United States)

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.

The role of inelastic processes in the temperature dependence of hall induced resistance oscillations

International Nuclear Information System (INIS)

Kunold, Alejandro; Torres, Manuel

2013-01-01

We develop a model of magnetoresistance oscillations induced by the Hall field in order to study the temperature dependence observed in recent experiments in two dimensional electron systems. The model is based on the solution of the von Neumann equation incorporating the exact dynamics of two-dimensional damped electrons in the presence of arbitrarily strong magnetic and dc electric fields, while the effects of randomly distributed neutral and charged impurities are perturbatively added. Both the effects of elastic impurity scattering as well as those related to inelastic processes play an important role. The theoretical predictions correctly reproduce the experimentally observed oscillations amplitude, provided that the quantum inelastic scattering rate obeys a T 2 temperature dependence, consistent with electron–electron interaction effects

Dynamical Friedel oscillations of a Fermi sea

Science.gov (United States)

Zhang, J. M.; Liu, Y.

2018-02-01

We study the scenario of quenching an interaction-free Fermi sea on a one-dimensional lattice ring by suddenly changing the potential of a site. From the point-of-view of the conventional Friedel oscillation, which is a static or equilibrium problem, it is of interest what temporal and spatial oscillations the local sudden quench will induce. Numerically, the primary observation is that for a generic site, the local particle density switches between two plateaus periodically in time. Making use of the proximity of the realistic model to an exactly solvable model and employing the Abel regularization to assign a definite value to a divergent series, we obtain an analytical formula for the heights of the plateaus, which turns out to be very accurate for sites not too close to the quench site. The unexpect relevance and the incredible accuracy of the Abel regularization are yet to be understood. Eventually, when the contribution of the defect mode is also taken into account, the plateaus for those sites close to or on the quench site can also be accurately predicted. We have also studied the infinite lattice case. In this case, ensuing the quench, the out-going wave fronts leave behind a stable density oscillation pattern. Because of some interesting single-particle property, this dynamically generated Friedel oscillation differs from its conventional static counterpart only by the defect mode.

The effect of near-surface convection on oscillation frequencies of stars

Science.gov (United States)

Hanasoge, Shravan

2015-08-01

Measurements of oscillation frequencies of the Sun and stars can provide important independent constraints on their internal structure and dynamics. Seismic models of these oscillations are used to connect structure and rotation of the star to its resonant frequencies, which are then compared with observations, the goal being that of minimizing the difference between the two. Even in the case of the Sun, for which structure models are highly tuned, observed frequencies show systematic deviations from modelled frequencies, a phenomenon referred to as the “surface term”. The dominant source of this systematic effect is thought to be vigorous near-surface convection, which is not well accounted for in both stellar modelling and mode-oscillation physics. Here we bring to bear the method of homogenization, applicable in the asymptotic limit of large wavelength (in comparison to the correlation scale of convection), to characterize the effect of small-scale surface convection on resonant-mode frequencies in the Sun. We show that the full oscillation equations, in the presence of temporally stationary 3-D flows, can be reduced to an effective “quiet-Sun” wave equation with altered sound speed, Brünt-Väisäla frequency and Lamb frequency. We derive the modified wave equation and relations for the appropriate averaging of three dimensional flows and thermal quantities to obtain the properties of this effective medium. Using flows obtained from three dimensional numerical simulations of near-surface convection, we quantify their effect on solar oscillation frequencies, and find that they are shifted systematically and substantially. We argue therefore that consistent interpretations of resonant frequencies must include modifications to the wave equation that effectively capture the impact of vigorous hydrodynamic convection.

Influence of Syringe Volume on Foam Stability in Sclerotherapy for Varicose Vein Treatment.

Science.gov (United States)

Bai, Taoping; Jiang, Wentao; Fan, Yubo

2018-05-01

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.

980-nm laser therapy versus varicose vein surgery in racially diverse Penang, Malaysia.

Science.gov (United States)

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.

Time dependent analysis of Xenon spatial oscillations in small power reactors; Analise temporal das oscilacoes espaciais de Xenonio em reatores de pequeno porte

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)

Isotropic oscillator in the space of constant positive curvature. Interbasis expansions

International Nuclear Information System (INIS)

Akopyan, E.M.; Pogosyan, G.S.; Sisakyan, A.N.; Vinitskij, S.I.

1997-01-01

The Schroedinger equation is thoroughly analysed for the isotropic oscillator in the three-dimensional space of constant positive curvature in the spherical and cylindrical systems of coordinates. The expansion coefficients between the spherical and cylindrical bases of the oscillator are calculated. It is shown that the relevant coefficients are expressed through the generalised hypergeometric functions 4 F 3 of the unit argument or 6j Racah symbols extended over their indices to the region of real values. Limiting transitions to a free motion and flat space are considered in detail. Elliptic bases of the oscillator are constructed in the form of expansion over the spherical and cylindrical bases. The corresponding expansion coefficients are shown to obey the three-term recurrence relations expansion coefficients are shown to obey the three-term recurrence relations

On the quantization of a nonlinear oscillator with quasi-harmonic behaviour

International Nuclear Information System (INIS)

Ranada, M.F.; Carinena, J.F.; Satander, M.

2006-01-01

Full text: (author)The quantum version of a non-linear oscillator, depending of a parameter λ, is studied. This λ-dependent system can be considered deformation of the harmonic oscillator in the sense that for λ→0 all the characteristics of the linear oscillator are recovered. This is a problem of quantization of a system with position-dependent mass and with a λ-dependent nonpolynominal rational potential. The quantization problem is solved using existence of a Killing vector, the λ-dependent Schroedinger equation is exactly solved and λ-dependent eigenenergies and eigenfunctions are obtained. The λ-dependent wave functions appear as related with a family of orthogonal polynomials that can be considered as deformations of the standard Hermite polynomials. In the second part, it is proved the superintegrability of the two-dimensional system

A New Quasi-Exactly Solvable Problem and Its Connection with an Anharmonic Oscillator

International Nuclear Information System (INIS)

Yang Dabao; Zhang Fulin; Chen Jingling

2010-01-01

The two-dimensional hydrogen with a linear potential in a magnetic field is solved by two different methods. Furthermore the connection between the model and an anharmonic oscillator is investigated by methods of KS transformation. (general)

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)

Discrete series representations for sl(2|1), Meixner polynomials and oscillator models

International Nuclear Information System (INIS)

Jafarov, E I; Van der Jeugt, J

2012-01-01

We explore a model for a one-dimensional quantum oscillator based on the Lie superalgebra sl(2|1). For this purpose, a class of discrete series representations of sl(2|1) is constructed, each representation characterized by a real number β > 0. In this model, the position and momentum operators of the oscillator are odd elements of sl(2|1) and their expressions involve an arbitrary parameter γ. In each representation, the spectrum of the Hamiltonian is the same as that of a canonical oscillator. The spectrum of a position operator can be continuous or infinite discrete, depending on the value of γ. We determine the position wavefunctions both in the continuous and the discrete case and discuss their properties. In the discrete case, these wavefunctions are given in terms of Meixner polynomials. From the embedding osp(1|2) subset of sl(2|1), it can be seen why the case γ = 1 corresponds to a paraboson oscillator. Consequently, taking the values (β, γ) = (1/2, 1) in the sl(2|1) model yields a canonical oscillator. (paper)

Adjoint method provides phase response functions for delay-induced oscillations.

Science.gov (United States)

Kotani, Kiyoshi; Yamaguchi, Ikuhiro; Ogawa, Yutaro; Jimbo, Yasuhiko; Nakao, Hiroya; Ermentrout, G Bard

2012-07-27

Limit-cycle oscillations induced by time delay are widely observed in various systems, but a systematic phase-reduction theory for them has yet to be developed. Here we present a practical theoretical framework to calculate the phase response function Z(θ), a fundamental quantity for the theory, of delay-induced limit cycles with infinite-dimensional phase space. We show that Z(θ) can be obtained as a zero eigenfunction of the adjoint equation associated with an appropriate bilinear form for the delay differential equations. We confirm the validity of the proposed framework for two biological oscillators and demonstrate that the derived phase equation predicts intriguing multimodal locking behavior.

Revisiting the quantum harmonic oscillator via unilateral Fourier transforms

International Nuclear Information System (INIS)

Nogueira, Pedro H F; Castro, Antonio S de

2016-01-01

The literature on the exponential Fourier approach to the one-dimensional quantum harmonic oscillator problem is revised and criticized. It is shown that the solution of this problem has been built on faulty premises. The problem is revisited via the Fourier sine and cosine transform method and the stationary states are properly determined by requiring definite parity and square-integrable eigenfunctions. (paper)

Attenuation of soliton oscillations in media with a negative bispersion law

International Nuclear Information System (INIS)

Burtsev, S.P.

1985-01-01

The evolution of small two-dimensional perturbations of a plane soliton are considered. The Cauchy problem for the linearized Kadomtsev-Petviashvili equation is solved. The asymptotic behaviour of the Green function at t → + infiinity yields the decrement of the soliton oscillations in media with a negative dispersion law

Conversion of thermall energy to mechanical work in the oscillations with steam condensation in pool water

International Nuclear Information System (INIS)

Aya, Izuo; Nariai, Hideki.

1988-01-01

Pressure and fluid oscillations with steam injection into pool water were discussed from the view point of the conversion of thermal energy into mechanical work. When the change of fluid state moves clockwise in the p-V diagram, the oscillation sustains since the thermal energy changes into positive work. The equations difining the mechanical work at the condensation oscillations were presented. The oscillation threshold determined by the condition that mechanical work became zero, coincided with the values derived by the linear oscillation theory. The changes of pressure and specific volume during chugging were also shown with one dimensional simulation analysis. The p-V diagrams at various chugging modes were presented with the movement of steam water interface, and the conversion efficiency of thermal energy to mechanical work was also discussed. (author)

Preliminary Results from Simulations of Temperature Oscillations in Stirling Engine Regenerator Matrices

DEFF Research Database (Denmark)

Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove

2006-01-01

The objective of this study has been to create a Stirling engine model for studying the effects of regenerator matrix temperature oscillations on Stirling engine performance. A one-dimensional model with axial discretisation of engine components has been formulated using the control volume method...

Harmonic oscillator states with integer and non-integer orbital angular momentum

International Nuclear Information System (INIS)

Land, Martin

2011-01-01

We study the quantum mechanical harmonic oscillator in two and three dimensions, with particular attention to the solutions as basis states for representing their respective symmetry groups — O(2), O(1,1), O(3), and O(2,1). The goal of this study is to establish a correspondence between Hilbert space descriptions found by solving the Schrodinger equation in polar coordinates, and Fock space descriptions constructed by expressing the symmetry operators in terms of creation/annihilation operators. We obtain wavefunctions characterized by a principal quantum number, the group Casimir eigenvalue, and one group generator whose eigenvalue is m + s, for integer m and real constant parameter s. For the three groups that contain O(2), the solutions split into two inequivalent representations, one associated with s = 0, from which we recover the familiar description of the oscillator as a product of one-dimensional solutions, and the other with s > 0 (in three dimensions, solutions are found for s = 0 and s = 1/2) whose solutions are non-separable in Cartesian coordinates, and are hence overlooked by the standard Fock space approach. The O(1,1) solutions are singlet states, restricted to zero eigenvalue of the symmetry operator, which represents the boost, not angular momentum. For O(2), a single set of creation and annihilation operators forms a ladder representation for the allowed oscillator states for any s, and the degeneracy of energy states is always finite. However, in three dimensions, the integer and half-integer eigenstates are qualitatively different: the former can be expressed as finite dimensional irreducible tensors under O(3) or O(2,1) while the latter exhibit infinite degeneracy. Creation operators that produce the allowed integer states by acting on the non-degenerate ground state are constructed as irreducible tensor products of the fundamental vector representation. However, the half-integer eigenstates are infinite-dimensional, as expected for the non

Phase synchronization of non-Abelian oscillators on small-world networks

Energy Technology Data Exchange (ETDEWEB)

Gu, Zhi-Ming [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Zhao, Ming [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China); Zhou, Tao [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)]. E-mail: zhutou@ustc.edu; Zhu, Chen-Ping [College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016 (China); Wang, Bing-Hong [Department of Modern Physics, University of Science and Technology of China, Hefei 230026 (China)

2007-02-26

In this Letter, by extending the concept of Kuramoto oscillator to the left-invariant flow on general Lie group, we investigate the generalized phase synchronization on networks. The analyses and simulations of some typical dynamical systems on Watts-Strogatz networks are given, including the n-dimensional torus, the identity component of 3-dimensional general linear group, the special unitary group, and the special orthogonal group. In all cases, the greater disorder of networks will predict better synchronizability, and the small-world effect ensures the global synchronization for sufficiently large coupling strength. The collective synchronized behaviors of many dynamical systems, such as the integrable systems, the two-state quantum systems and the top systems, can be described by the present phase synchronization frame. In addition, it is intuitive that the low-dimensional systems are more easily to synchronize, however, to our surprise, we found that the high-dimensional systems display obviously synchronized behaviors in regular networks, while these phenomena cannot be observed in low-dimensional systems.

Phase synchronization of non-Abelian oscillators on small-world networks

International Nuclear Information System (INIS)

Gu, Zhi-Ming; Zhao, Ming; Zhou, Tao; Zhu, Chen-Ping; Wang, Bing-Hong

2007-01-01

In this Letter, by extending the concept of Kuramoto oscillator to the left-invariant flow on general Lie group, we investigate the generalized phase synchronization on networks. The analyses and simulations of some typical dynamical systems on Watts-Strogatz networks are given, including the n-dimensional torus, the identity component of 3-dimensional general linear group, the special unitary group, and the special orthogonal group. In all cases, the greater disorder of networks will predict better synchronizability, and the small-world effect ensures the global synchronization for sufficiently large coupling strength. The collective synchronized behaviors of many dynamical systems, such as the integrable systems, the two-state quantum systems and the top systems, can be described by the present phase synchronization frame. In addition, it is intuitive that the low-dimensional systems are more easily to synchronize, however, to our surprise, we found that the high-dimensional systems display obviously synchronized behaviors in regular networks, while these phenomena cannot be observed in low-dimensional systems

A DUPLICATED GREAT SAPHENOUS VEIN AND CLINICAL SIGNIFICANCE FOR VARICOSITY. Duplicación de la vena safena magna y significado clínico de las várices

Directory of Open Access Journals (Sweden)

Waseem Al Talalwah

2016-03-01

Full Text Available En varios estudios se ha relacionado la vena safena magna doble con dilataciones varicosas. Durante una clase de disección de pre-grado de la extremidad inferior se encontró una doble vena safena magna unilateral en el miembro inferior izquierdo de un cadáver masculino. La incidencia de esta variación fue del 1,3% de todos los especímenes muestra. En este trabajo se reporta la variabilidad del drenaje venoso de las extremidades inferiores para mejorar la conciencia para los radiólogos vasculares y proporcionar además una opción adicional en la cirugía de bypass de la arteria coronaria para evitar las várices iatrogénicas. A double great saphenous vein has been associated with varicosity in a number of studies. During routine undergraduate dissection of the lower limb a unilateral double great saphenous was found in the left lower limb of a male cadaver. The incidence of this variation was 1.3% of all specimens. This paper reports the variability of lower limb venous drainage to increase the awareness for vascular radiologists and provide further an additional option in coronary artery bypass surgery to avoid iatrogenic varicosity.

Quenching oscillating behaviors in fractional coupled Stuart-Landau oscillators

Science.gov (United States)

Sun, Zhongkui; Xiao, Rui; Yang, Xiaoli; Xu, Wei

2018-03-01

Oscillation quenching has been widely studied during the past several decades in fields ranging from natural sciences to engineering, but investigations have so far been restricted to oscillators with an integer-order derivative. Here, we report the first study of amplitude death (AD) in fractional coupled Stuart-Landau oscillators with partial and/or complete conjugate couplings to explore oscillation quenching patterns and dynamics. It has been found that the fractional-order derivative impacts the AD state crucially. The area of the AD state increases along with the decrease of the fractional-order derivative. Furthermore, by introducing and adjusting a limiting feedback factor in coupling links, the AD state can be well tamed in fractional coupled oscillators. Hence, it provides one an effective approach to analyze and control the oscillating behaviors in fractional coupled oscillators.

Beating of Aharonov-Bohm oscillations in a closed-loop interferometer

International Nuclear Information System (INIS)

Jo, Sanghyun; Chang, Dong-In; Lee, Hu-Jong; Khym, Gyong Luck; Kang, Kicheon; Chung, Yunchul; Mahalu, Diana; Umansky, Vladimir

2007-01-01

One of the points at issue with closed-loop-type interferometers is beating in the Aharonov-Bohm (AB) oscillations. Recent observations suggest the possibility that the beating results from the Berry-phase pickup by the conducting electrons in materials with the strong spin-orbit interaction (SOI). In this study, we also observed beats in the AB oscillations in a gate-defined closed-loop interferometer fabricated on a GaAs/Al 0.3 Ga 0.7 As two-dimensional electron-gas heterostructure. Since this heterostructure has very small SOI, the picture of the Berry-phase pickup is ruled out. The observation of beats in this study, with the controllability of forming a single transverse subband mode in both arms of our gate-defined interferometer, also rules out the often-claimed multiple transverse subband effect. It is observed that nodes of the beats with an h/2e period exhibit a parabolic distribution for varying the side gate. These results are shown to be well interpreted, without resorting to the SOI effect, by the existence of two-dimensional multiple longitudinal modes in a single transverse subband. The Fourier spectrum of measured conductance, despite showing multiple h/e peaks with the magnetic-field dependence that are very similar to that from strong-SOI materials, can also be interpreted as the two-dimensional multiple-longitudinal-modes effect

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

Phase-space treatment of the driven quantum harmonic oscillator

Indian Academy of Sciences (India)

2017-02-22

Feb 22, 2017 ... i.e., ρ(θ,q ,p |q,p,t) is a measure of the interference effects associated ... an oscillating electric field, when the initial state is cho- sen as a .... The conclusive effect is that. A±(q,p,t) ...... wave functions ±(q,p,t) stem from the time depen- dence of ..... define a two-dimensional cell in phase space, which is centred ...

From ordinary to discrete quantum mechanics: The Charlier oscillator and its coalgebra symmetry

Energy Technology Data Exchange (ETDEWEB)

Latini, D., E-mail: latini@fis.uniroma3.it [Department of Mathematics and Physics and INFN, Roma Tre University, Via della Vasca Navale 84, I-00146 Rome (Italy); Riglioni, D. [Department of Mathematics and Physics, Roma Tre University, Via della Vasca Navale 84, I-00146 Rome (Italy)

2016-10-14

The coalgebraic structure of the harmonic oscillator is used to underline possible connections between continuous and discrete superintegrable models which can be described in terms of SUSY discrete quantum mechanics. A set of 1-parameter algebraic transformations is introduced in order to generate a discrete representation for the coalgebraic harmonic oscillator. This set of transformations is shown to play a role in the generalization of classical orthogonal polynomials to the realm of discrete orthogonal polynomials in the Askey scheme. As an explicit example the connection between Hermite and Charlier oscillators, that share the same coalgebraic structure, is presented and a two-dimensional maximally superintegrable version of the Charlier oscillator is constructed. - Highlights: • We construct a discrete quantum version of the harmonic oscillator. • We solve the spectral problem on the lattice. • We introduce the coalgebra symmetry in real discrete Quantum Mechanics (rdQM). • The coalgebra is used to extend the system to higher dimensions preserving its superintegrability. • We explicitly write down a discrete version of both the angular momentum and the Demkov–Fradkin Tensor.

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.

Partially coherent twisted states in arrays of coupled phase oscillators

Energy Technology Data Exchange (ETDEWEB)

Omel' chenko, Oleh E.; Wolfrum, Matthias [Weierstrass Institute, Mohrenstrasse 39, 10117 Berlin (Germany); Laing, Carlo R. [INMS, Massey University, Private Bag 102-904 NSMC, Auckland (New Zealand)

2014-06-15

We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system.

Partially coherent twisted states in arrays of coupled phase oscillators

International Nuclear Information System (INIS)

Omel'chenko, Oleh E.; Wolfrum, Matthias; Laing, Carlo R.

2014-01-01

We consider a one-dimensional array of phase oscillators with non-local coupling and a Lorentzian distribution of natural frequencies. The primary objects of interest are partially coherent states that are uniformly “twisted” in space. To analyze these, we take the continuum limit, perform an Ott/Antonsen reduction, integrate over the natural frequencies, and study the resulting spatio-temporal system on an unbounded domain. We show that these twisted states and their stability can be calculated explicitly. We find that stable twisted states with different wave numbers appear for increasing coupling strength in the well-known Eckhaus scenario. Simulations of finite arrays of oscillators show good agreement with results of the analysis of the infinite system

Optimal Control Strategy Search Using a Simplest 3-D PWR Xenon Oscillation Simulator

International Nuclear Information System (INIS)

Yoichiro, Shimazu

2004-01-01

Power spatial oscillations due to the transient xenon spatial distribution are well known as xenon oscillation in large PWRs. When the reactor size becomes larger than the current design, then even radial oscillations can be also divergent. Even if the radial oscillation is convergent, when some control rods malfunction occurs, it is necessary to suppress the oscillation in as short time as possible. In such cases, optimal control strategy is required. Generally speaking the optimality search based on the modern control theory requires a lot of calculation for the evaluation of state variables. In the case of control rod malfunctions the xenon oscillation could be three dimensional. In such case, direct core calculations would be inevitable. From this point of view a very simple model, only four point reactor model, has been developed and verified. In this paper, an example of a procedure and the results for optimal control strategy search are presented. It is shown that we have only one optimal strategy within a half cycle of the oscillation with fixed control strength. It is also shown that a 3-D xenon oscillation introduced by a control rod malfunction can not be controlled by only one control step as can be done for axial oscillations. They might be quite strong limitations to the operators. Thus it is recommended that a strategy generator, which is quick in analyzing and easy to use, might be installed in a monitoring system or operator guiding system. (author)

Oscillators and Eigenvalues

DEFF Research Database (Denmark)

Lindberg, Erik

1997-01-01

In order to obtain insight in the nature of nonlinear oscillators the eigenvalues of the linearized Jacobian of the differential equations describing the oscillator are found and displayed as functions of time. A number of oscillators are studied including Dewey's oscillator (piecewise linear wit...... with negative resistance), Kennedy's Colpitts-oscillator (with and without chaos) and a new 4'th order oscillator with hyper-chaos....

On One Means of Hard Excitation of Oscillations in Nonlinear Flutter Systems

Directory of Open Access Journals (Sweden)

S. D. Glyzin

2014-01-01

Full Text Available Considered are so-called finite-dimensional flutter systems, i.e. systems of ordinary differential equations, arising from Galerkin approximations of certain boundary value problems of aeroelasticity theory as well as from a number of radiophysics applications. We study small oscillations of these equations in case of 1 : 3 resonance. By combining analytical and numerical methods, it is concluded that the mentioned resonance can cause a hard excitation of oscillations. Namely, for flutter systems shown is the possibility of coexistence, along with the stable zero state, of stable invariant tori of arbitrary finite dimension as well as chaotic attractors.

An atypical case of postsurgical complex regional pain syndrome in a patient having nonhealing varicose venous ulcer treated by lumbar sympathectomy

Directory of Open Access Journals (Sweden)

Kailash Kothari

2017-01-01

Full Text Available Complex regional pain syndrome (CRPS of the lower limb is a relatively uncommon entity as compared to CRPS of the upper extremity. Literature search has revealed only 2 retrospective case series and a single case report of lower extremity CRPS type I from 1975 to 2014 on Pubmed, isolated cases of CRPS type I of lower extremity have also been reported following knee surgeries and arthroscopies. This report presents a case of lower limb CRPS type I, following surgery for varicose vein ulcer. Pain was not relieved with medications. Diagnostic lumbar sympathectomy was done and patient had tremendous relief of pain following that, proving sympathetic mediated pain of the involved limb.

Investigation on multi-frequency oscillations in InGaAs planar Gunn diode with multiple anode-cathode spacings

Science.gov (United States)

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.

Quasi-periodic bifurcations and “amplitude death” in low-dimensional ensemble of van der Pol oscillators

Energy Technology Data Exchange (ETDEWEB)

Emelianova, Yu.P., E-mail: yuliaem@gmail.com [Department of Electronics and Instrumentation, Saratov State Technical University, Polytechnicheskaya 77, Saratov 410054 (Russian Federation); Kuznetsov, A.P., E-mail: apkuz@rambler.ru [Kotel' nikov' s Institute of Radio-Engineering and Electronics of RAS, Saratov Branch, Zelyenaya 38, Saratov 410019 (Russian Federation); Turukina, L.V., E-mail: lvtur@rambler.ru [Kotel' nikov' s Institute of Radio-Engineering and Electronics of RAS, Saratov Branch, Zelyenaya 38, Saratov 410019 (Russian Federation); Institute for Physics and Astronomy, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam (Germany)

2014-01-10

The dynamics of the four dissipatively coupled van der Pol oscillators is considered. Lyapunov chart is presented in the parameter plane. Its arrangement is discussed. We discuss the bifurcations of tori in the system at large frequency detuning of the oscillators. Here are quasi-periodic saddle-node, Hopf and Neimark–Sacker bifurcations. The effect of increase of the threshold for the “amplitude death” regime and the possibilities of complete and partial broadband synchronization are revealed.

Theoretical Investigation of Current Instabilities and Terahertz Oscillations in a Two-Dimensional Electron Fluid

National Research Council Canada - National Science Library

Dyakonov, M

1997-01-01

The purpose of this work is to develop further the theory of novel mechanisms for generation and detection of electromagnetic radiation in the terahertz range using the plasma oscillations of the two...

Geometry of the isotropic oscillator driven by the conformal mode

Energy Technology Data Exchange (ETDEWEB)

Galajinsky, Anton [Tomsk Polytechnic University, School of Physics, Tomsk (Russian Federation)

2018-01-15

Geometrization of a Lagrangian conservative system typically amounts to reformulating its equations of motion as the geodesic equations in a properly chosen curved spacetime. The conventional methods include the Jacobi metric and the Eisenhart lift. In this work, a modification of the Eisenhart lift is proposed which describes the isotropic oscillator in arbitrary dimension driven by the one-dimensional conformal mode. (orig.)

Periodic oscillations in linear continuous media coupled with nonlinear discrete systems

International Nuclear Information System (INIS)

Lupini, R.

1998-01-01

A general derivation of partial differential equations with boundary conditions in the form of ordinary differential equations is obtained using the principle of stationary action for a Lagrangian function composed of continuous plus discrete parts in interaction across the boundaries of a 1-dimensional medium. This approach leads directly to the theorem of energy conservation. For linear continuous medium, homogeneous Dirichlet condition at one boundary, and nonlinear oscillator at the other boundary, the entire differential problem reduces to a nonlinear differential-difference equation of neutral type and of the second order. The lag parameter is τ = l/c, where c is the phase speed, l the length of the continuum. The Author investigate the problem of the occurrence of periodic solutions of period integer multiple of the lag (super harmonic solutions) in the case of zero inertia of the boundary system. The problem for such oscillations is shown to reduce to systems of ordinary differential equations with matching conditions in a phase space of lower dimensionality: Phase-plane techniques are used to determine solutions of period 4τ, 8τ and 6τ

Shubnikov-de Haas oscillations in bulk ZrT e5 single crystals: Evidence for a weak topological insulator

Science.gov (United States)

Lv, Yang-Yang; Zhang, Bin-Bin; Li, Xiao; Zhang, Kai-Wen; Li, Xiang-Bing; Yao, Shu-Hua; Chen, Y. B.; Zhou, Jian; Zhang, Shan-Tao; Lu, Ming-Hui; Li, Shao-Chun; Chen, Yan-Feng

2018-03-01

The study of ZrT e5 crystals is revived because of the recent theoretical prediction of topological phase in bulk ZrT e5 . However, the current conclusions for the topological character of bulk ZrT e5 are quite contradictory. To resolve this puzzle, we here identify the Berry phase on both b - and c planes of high-quality ZrT e5 crystals by the Shubnikov-de-Hass (SdH) oscillation under tilted magnetic field at 2 K. The angle-dependent SdH oscillation frequency, both on b - and c planes of ZrT e5 , demonstrates the two-dimensional feature. However, phase analysis of SdH verifies that a nontrivial π-Berry phase is observed in the c -plane SdH oscillation, but not in the b -plane one. Compared to bulk Fermi surface predicted by the first-principle calculation, the two-dimensional-like behavior of SdH oscillation measured at b plane comes from the bulk electron. Based on these analyses, it is suggested that bulk ZrT e5 at low temperature (˜2 K) belongs to a weak topological insulator, rather than Dirac semimetal or strong topological insulator as reported previously.

Flow around an oscillating cylinder: computational issues

Energy Technology Data Exchange (ETDEWEB)

Jiang, Fengjian; Gallardo, José P; Pettersen, Bjørnar [Department of Marine Technology, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Andersson, Helge I, E-mail: fengjian.jiang@ntnu.no [Department of Energy and Process Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

2017-10-15

We consider different computational issues related to the three-dimensionalities of the flow around an oscillating circular cylinder. The full time-dependent Navier–Stokes equations are directly solved in a moving reference frame by introducing a forcing term. The choice of quantitative validation criteria is discussed and discrepancies of previously published results are addressed. The development of Honji vortices shows that short simulation times may lead to incorrect quasi-stable vortex patterns. The viscous decay of already established Honji vortices is also examined. (paper)

Collective oscillations of twin boundaries in high temperature superconductors as an acoustic analogue of two-dimensional plasmons

International Nuclear Information System (INIS)

Kosevich, Yu.A.; Syrkin, E.S.

1990-06-01

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∼K 1/2 , characteristics 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 in an attempt to explain the anomalies of low temperature thermodynamic and kinetic characteristics of high-T 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 high elastic anisotropy of the solid phases enlarges the range of existence of such excitations in solid-state systems. The 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. (author). 18 refs

The structure of the Hamiltonian in a finite-dimensional formalism based on Weyl's quantum mechanics

International Nuclear Information System (INIS)

Santhanam, T.S.; Madivanane, S.

1982-01-01

Any discussion on finite-dimensional formulation of quantum mechanics involves the Sylvester matrix (finite Fourier transform). In the usual formulation, a remarkable relation exists that gives the Fourier transform as the exponential of the Hamiltonian of a simple harmonic oscillator. In this paper, assuming that such a relation holds also in the finite dimensional case, we extract the logarithm of the Sylvester matrix and in some cases this can be interpreted as the Hamiltonian of the truncated oscillator. We calculate the Hamiltonian matrix explicitly for some special cases of n = 3,4. (author)

The topological reconstruction of forced oscillators

International Nuclear Information System (INIS)

Solari, Hernan G.; Natiello, Mario A.

2009-01-01

Periodically forced oscillators are among the simplest dynamical systems capable to display chaos. They can be described by the variables position and velocity, together with the phase of the force. Their phase-space corresponds therefore to R 2 xS 1 . The organization of the periodic orbits can be displayed with braids having only positive crossings. Topological characterization of dynamical systems actually began to be explored in physics on this family of problems. In this work we show that, in general, it is not possible to produce a 3-dimensional imbedding of the solutions of a forced oscillator in terms of differential imbeddings based on sampling the position only. However, it may be possible to uncover a description of the phase variable from the sampled time-series, thus producing a faithful representation of the data. We proceed to formulate new tests in order to check whether proposed imbeddings can be accepted as such. We illustrate the manuscript throughout with an example corresponding to a model of Benard-Marangoni convection.

Quantum oscillation and nontrivial transport in the Dirac semimetal Cd_3As_2 nanodevice

International Nuclear Information System (INIS)

Pan, Haiyang; Wei, Zhongxia; Zhao, Bo; Song, Fengqi; Wang, Baigeng; Zhang, Kang; Gao, Ming; Wang, Xuefeng; Zhang, Rong; Wang, Jue; Han, Min; Pi, Li

2016-01-01

Here, we report on the Shubnikov-de Haas oscillation in high-quality Cd_3As_2 nanowires grown by a chemical vapor deposition approach. The dominant transport of topological Dirac fermions is evident by the nontrivial Berry phase in the Landau Fan diagram. The quantum oscillations rise at a small field of 2 T and preserves up to 100 K, revealing a sizeable Landau level gap and a device mobility of 2138 cm"2" V"−"1" s"−"1. The angle-variable oscillations indicate the isotropy of the bulk Dirac transport. The large estimated mean free path makes the Cd_3As_2 nanowire a promising platform for the one-dimensional transport of Dirac semimetals.

On the formation of fold-type oscillation marks in the continuous casting of steel.

Science.gov (United States)

Vynnycky, M; Saleem, S; Devine, K M; Florio, B J; Mitchell, S L; O'Brien, S B G

2017-06-01

Asymptotic methods are employed to revisit an earlier model for oscillation-mark formation in the continuous casting of steel. A systematic non-dimensionalization of the governing equations, which was not carried out previously, leads to a model with 12 dimensionless parameters. Analysis is provided in the same parameter regime as for the earlier model, and surprisingly simple analytical solutions are found for the oscillation-mark profiles; these are found to agree reasonably well with the numerical solution in the earlier model and very well with fold-type oscillation marks that have been obtained in more recent experimental work. The benefits of this approach, when compared with time-consuming numerical simulations, are discussed in the context of auxiliary models for macrosegregation and thermomechanical stresses and strains.

Regular and irregular patterns of self-localized excitation in arrays of coupled phase oscillators

Energy Technology Data Exchange (ETDEWEB)

Wolfrum, Matthias; Omel' chenko, Oleh E. [Weierstrass Institute, Mohrenstrasse 39, Berlin 10117 (Germany); Sieber, Jan [College of Engineering, Mathematics and Physical Sciences, University of Exeter, North Park Road, Exeter EX4 4QF (United Kingdom)

2015-05-15

We study a system of phase oscillators with nonlocal coupling in a ring that supports self-organized patterns of coherence and incoherence, called chimera states. Introducing a global feedback loop, connecting the phase lag to the order parameter, we can observe chimera states also for systems with a small number of oscillators. Numerical simulations show a huge variety of regular and irregular patterns composed of localized phase slipping events of single oscillators. Using methods of classical finite dimensional chaos and bifurcation theory, we can identify the emergence of chaotic chimera states as a result of transitions to chaos via period doubling cascades, torus breakup, and intermittency. We can explain the observed phenomena by a mechanism of self-modulated excitability in a discrete excitable medium.

Exact Time-Dependent Wave Functions of a Confined Time-Dependent Harmonic Oscillator with Two Moving Boundaries

International Nuclear Information System (INIS)

Lo, C.F.

2009-01-01

By applying the standard analytical techniques of solving partial differential equations, we have obtained the exact solution in terms of the Fourier sine series to the time-dependent Schroedinger equation describing a quantum one-dimensional harmonic oscillator of time-dependent frequency confined in an infinite square well with the two walls moving along some parametric trajectories. Based upon the orthonormal basis of quasi-stationary wave functions, the exact propagator of the system has also been analytically derived. Special cases like (i) a confined free particle, (ii) a confined time-independent harmonic oscillator, and (iii) an aging oscillator are examined, and the corresponding time-dependent wave functions are explicitly determined. Besides, the approach has been extended to solve the case of a confined generalized time-dependent harmonic oscillator for some parametric moving boundaries as well. (general)

Envelope detection using temporal magnetization dynamics of resonantly interacting spin-torque oscillator

Science.gov (United States)

Nakamura, Y.; Nishikawa, M.; Osawa, H.; Okamoto, Y.; Kanao, T.; Sato, R.

2018-05-01

In this article, we propose the detection method of the recorded data pattern by the envelope of the temporal magnetization dynamics of resonantly interacting spin-torque oscillator on the microwave assisted magnetic recording for three-dimensional magnetic recording. We simulate the envelope of the waveform from recorded dots with the staggered magnetization configuration, which are calculated by using a micromagnetic simulation. We study the data detection methods for the envelope and propose a soft-output Viterbi algorithm (SOVA) for partial response (PR) system as a signal processing system for three dimensional magnetic recording.

Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators

KAUST Repository

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.

Nature's Autonomous Oscillators

Science.gov (United States)

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.

Harmonic-oscillator pattern arising from an algebraic approach to chiral symmetry

CERN Document Server

Buccella, F; Savoy, C A

1972-01-01

The Weinberg equation for the (mass)/sup 2/ operator (Q/sub 5//sup +/, (Q/sub 5//sup +/, m/sup 2/))=0, between meson states, is saturated in a perturbative approach. The generator Z of the mixing operators is completely established as Z=(W*M)/sub z/, where W is the W-spin operator and M is the co-ordinate of the three-dimensional harmonic oscillator. In a perturbative expansion of the (mass)/sup 2/ operator, the lowest term consists of two parts, the harmonic-oscillator energy and a spin-orbit coupling of the form (-1)/sup L+1/(L.S+/sup 1///sub 2 /). The resulting (mass)/sup 2/ consists of families of equispaced linearly rising trajectories. (11 refs).

Mean-field behavior in coupled oscillators with attractive and repulsive interactions.

Science.gov (United States)

Hong, Hyunsuk; Strogatz, Steven H

2012-05-01

We consider a variant of the Kuramoto model of coupled oscillators in which both attractive and repulsive pairwise interactions are allowed. The sign of the coupling is assumed to be a characteristic of a given oscillator. Specifically, some oscillators repel all the others, thus favoring an antiphase relationship with them. Other oscillators attract all the others, thus favoring an in-phase relationship. The Ott-Antonsen ansatz is used to derive the exact low-dimensional dynamics governing the system's long-term macroscopic behavior. The resulting analytical predictions agree with simulations of the full system. We explore the effects of changing various parameters, such as the width of the distribution of natural frequencies and the relative strengths and proportions of the positive and negative interactions. For the particular model studied here we find, unexpectedly, that the mixed interactions produce no new effects. The system exhibits conventional mean-field behavior and displays a second-order phase transition like that found in the original Kuramoto model. In contrast to our recent study of a different model with mixed interactions [Phys. Rev. Lett. 106, 054102 (2011)], the π state and traveling-wave state do not appear for the coupling type considered here.

Wake structure and thrust generation of a flapping foil in two-dimensional flow

DEFF Research Database (Denmark)

Andersen, Anders Peter; Bohr, Tomas; Schnipper, Teis

2017-01-01

We present a combined numerical (particle vortex method) and experimental (soap film tunnel) study of a symmetric foil undergoing prescribed oscillations in a two-dimensional free stream. We explore pure pitching and pure heaving, and contrast these two generic types of kinematics. We compare...... measurements and simulations when the foil is forced with pitching oscillations, and we find a close correspondence between flow visualisations using thickness variations in the soap film and the numerically determined vortex structures. Numerically, we determine wake maps spanned by oscillation frequency...

Oscillating heat pipes

CERN Document Server

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...

Analytical investigation of a one-dimensional homogenized model for a pressurized water reactor core

International Nuclear Information System (INIS)

Benner, J.; Schumann, U.

1981-01-01

A one-dimensional homogenized model for dynamic fluid-structure interaction in a pressurized water reactor core is used to study the influence of the virtual density and spacer's stiffness. The model consists of a linear system of partial differential equations for fluid velocity, rod velocity and pressure. For these equations analytical solutions are deduced for boundary conditions prescribing either periodic wall oscillations or linearly growing wall accelerations from rest. The theoretical model for the virtual density is verified by comparison to an experiment. For zero spacer stiffness, purely acoustic oscillations appear. For positive spacer stiffness, additional oscillations arise with relative rod motions. The wavelengths of the latter oscillations are small for weak spacers. Large numerical effort would be required in a more complete three-dimensional core-model to resolve such short wave lengths. In fact in a typical core the spacer's stiffness csub(S) is small in comparison to the fluid bulk modulus K. For csub(s)/K <= 0.1 it might be appropriate to neglect the influence of the spacers. (orig.)

Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators

KAUST Repository

Talukdar, Abdul Hafiz Ibne; Radwan, Ahmed G.; Salama, Khaled N.

2012-01-01

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

Quantum mechanical treatment of a constrained particle on two dimensional sphere

Energy Technology Data Exchange (ETDEWEB)

Jahangiri, L., E-mail: laleh.jahangiry@yahoo.com; Panahi, H., E-mail: t-panahi@guilan.ac.ir

2016-12-15

In this work, we study the motion of a particle on two dimensional sphere. By writing the Schrodinger equation, we obtain the wave function and energy spectra for three dimensional harmonic oscillator potential plus trigonometric Rosen–Morse non-central potential. By letting three special cases for intertwining operator, we investigate the energy spectra and wave functions for Smorodinsky–Winternitz potential model.

Synchronization of mobile chaotic oscillator networks

Energy Technology Data Exchange (ETDEWEB)

Fujiwara, Naoya, E-mail: fujiwara@csis.u-tokyo.ac.jp [Center for Spatial Information Science, The University of Tokyo, 277-8568 Chiba (Japan); Kurths, Jürgen [Potsdam Institute for Climate Impact Research (PIK), 14473 Potsdam, Germany and Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen (United Kingdom); Díaz-Guilera, Albert [Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain and Universitat de Barcelona Institute of Complex Systems (UBICS), Universitat de Barcelona, Barcelona (Spain)

2016-09-15

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.

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.

Synchronization of mobile chaotic oscillator networks.

Science.gov (United States)

Fujiwara, Naoya; Kurths, Jürgen; Díaz-Guilera, Albert

2016-09-01

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.

Nonlinear theory for axisymmetric self-similar two-dimensional oscillations of electrons in cold plasma with constant proton background

Science.gov (United States)

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.

Clinical effectiveness and cost-effectiveness of foam sclerotherapy, endovenous laser ablation and surgery for varicose veins: results from the Comparison of LAser, Surgery and foam Sclerotherapy (CLASS) randomised controlled trial.

Science.gov (United States)

Brittenden, Julie; Cotton, Seonaidh C; Elders, Andrew; Tassie, Emma; Scotland, Graham; Ramsay, Craig R; Norrie, John; Burr, Jennifer; Francis, Jill; Wileman, Samantha; Campbell, Bruce; Bachoo, Paul; Chetter, Ian; Gough, Michael; Earnshaw, Jonothan; Lees, Tim; Scott, Julian; Baker, Sara A; MacLennan, Graeme; Prior, Maria; Bolsover, Denise; Campbell, Marion K

2015-04-01

Foam sclerotherapy (foam) and endovenous laser ablation (EVLA) have emerged as alternative treatments to surgery for patients with varicose veins, but uncertainty exists regarding their effectiveness in the medium to longer term. To assess the clinical effectiveness and cost-effectiveness of foam, EVLA and surgery for the treatment of varicose veins. A parallel-group randomised controlled trial (RCT) without blinding, and economic modelling evaluation. Eleven UK specialist vascular centres. Seven hundred and ninety-eight patients with primary varicose veins (foam, n = 292; surgery, n = 294; EVLA, n = 212). Patients were randomised between all three treatment options (eight centres) or between foam and surgery (three centres). Disease-specific [Aberdeen Varicose Vein Questionnaire (AVVQ)] and generic [European Quality of Life-5 Dimensions (EQ-5D), Short Form questionnaire-36 items (SF-36) physical and mental component scores] quality of life (QoL) at 6 months. Cost-effectiveness as cost per quality-adjusted life-year (QALY) gained. Quality of life at 6 weeks; residual varicose veins; Venous Clinical Severity Score (VCSS); complication rates; return to normal activity; truncal vein ablation rates; and costs. The results appear generalisable in that participants' baseline characteristics (apart from a lower-than-expected proportion of females) and post-treatment improvement in outcomes were comparable with those in other RCTs. The health gain achieved in the AVVQ with foam was significantly lower than with surgery at 6 months [effect size -1.74, 95% confidence interval (CI) -2.97 to -0.50; p = 0.006], but was similar to that achieved with EVLA. The health gain in SF-36 mental component score for foam was worse than that for EVLA (effect size 1.54, 95% CI 0.01 to 3.06; p = 0.048) but similar to that for surgery. There were no differences in EQ-5D or SF-36 component scores in the surgery versus foam or surgery versus EVLA comparisons at 6 months. The

Reactor oscillator - I - III, Part I; Reaktorski oscilator - I-III, I Deo

Energy Technology Data Exchange (ETDEWEB)

Lolic, B [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku reaktora, Vinca, Beograd (Serbia and Montenegro)

1961-12-15

Project 'Reactor oscillator' covers the following activities: designing reactor oscillators for reactors RA and RB with detailed engineering drawings; constructing and mounting of the oscillator; designing and constructing the appropriate electronic equipment for the oscillator; measurements at the RA and RB reactors needed for completing the oscillator construction.

A finite oscillator model related to sl(2|1)

International Nuclear Information System (INIS)

Jafarov, E I; Van der Jeugt, J

2012-01-01

We investigate a new model for the finite one-dimensional quantum oscillator based upon the Lie superalgebra sl(2|1). In this setting, it is natural to present the position and momentum operators of the oscillator as odd elements of the Lie superalgebra. The model involves a parameter p (0 j of sl(2|1), the Hamiltonian has the usual equidistant spectrum. The spectrum of the position operator is discrete and turns out to be of the form ±√k, where k = 0, 1, …, j. We construct the discrete position wavefunctions, which are given in terms of certain Krawtchouk polynomials. These wavefunctions have appealing properties, as can already be seen from their plots. The model is sufficiently simple in the sense that the corresponding discrete Fourier transform (relating position wavefunctions to momentum wavefunctions) can be constructed explicitly. (paper)

Hidden symmetries in one-dimensional quantum Hamiltonians

International Nuclear Information System (INIS)

Curado, E.M.F.; Rego-Monteiro, M.A.; Nazareno, H.N.

2000-11-01

We construct a Heisenberg-like algebra for the one dimensional infinite square-well potential in quantum mechanics. The number-type and ladder operators are realized in terms of physical operators of the system as in the harmonic oscillator algebra. These physical operators are obtained with the help of variables used in a recently developed non commutative differential calculus. This square-well algebra is an example of an algebra in large class of generalized Heisenberg algebras recently constructed. This class of algebras also contains q-oscillators as a particular case. We also show here how this general algebra can address hidden symmetries present in several quantum systems. (author)

Quantum oscillator on CPn in a constant magnetic field

International Nuclear Information System (INIS)

Bellucci, Stefano; Nersessian, Armen; Yeranyan, Armen

2004-01-01

We construct the quantum oscillator interacting with a constant magnetic field on complex projective spaces CP N , as well as on their noncompact counterparts, i.e., the N-dimensional Lobachewski spaces L N . We find the spectrum of this system and the complete basis of wave functions. Surprisingly, the inclusion of a magnetic field does not yield any qualitative change in the energy spectrum. For N>1 the magnetic field does not break the superintegrability of the system, whereas for N=1 it preserves the exact solvability of the system. We extend these results to the cones constructed over CP N and L N , and perform the Kustaanheimo-Stiefel transformation of these systems to the three dimensional Coulomb-like systems

Oscillator monitor

International Nuclear Information System (INIS)

McNeill, G.A.

1981-01-01

Present high-speed data acquisition systems in nuclear diagnostics use high-frequency oscillators to provide timing references for signals recorded on fast, traveling-wave oscilloscopes. An oscillator's sinusoidal wave shape is superimposed on the recorded signal with each cycle representing a fixed time increment. During data analysis the sinusoid is stripped from the signal, leaving a clean signal shape with known timing. Since all signal/time relationships are totally dependant upon working oscillators, these critical devices must have remote verification of proper operation. This manual presents the newly-developed oscillator monitor which will provide the required verification

Anisotropic inharmonic Higgs oscillator and related (MICZ-)Kepler-like systems

International Nuclear Information System (INIS)

Nersessian, Armen; Yeghikyan, Vahagn

2008-01-01

We propose the integrable (pseudo)spherical generalization of the four-dimensional anisotropic oscillator with additional nonlinear potential. Performing its Kustaanheimo-Stiefel transformation we then obtain the pseudospherical generalization of the MICZ-Kepler system with linear and cos θ potential terms. We also present the generalization of the parabolic coordinates, in which this system admits the separation of variables. Finally, we get the spherical analog of the presented MICZ-Kepler-like system

Co-existing hidden attractors in a radio-physical oscillator system

DEFF Research Database (Denmark)

Kuznetsov, A. P.; Kuznetsov, S. P.; Mosekilde, Erik

2015-01-01

The term `hidden attractor' relates to a stable periodic, quasiperiodic or chaotic state whose basin of attraction does not overlap with the neighborhood of an unstable equilibrium point. Considering a three-dimensional oscillator system that does not allow for the existence of an equilibrium point...... frequency, describe the bifurcations through which hidden attractors of different type arise and disappear, and illustrate the form of the basins of attraction....

The Motion of a Leaking Oscillator: A Study for the Physics Class

Science.gov (United States)

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…

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

Quantum quench in an atomic one-dimensional Ising chain.

Science.gov (United States)

Meinert, F; Mark, M J; Kirilov, E; Lauber, K; Weinmann, P; Daley, A J; Nägerl, H-C

2013-08-02

We study nonequilibrium dynamics for an ensemble of tilted one-dimensional atomic Bose-Hubbard chains after a sudden quench to the vicinity of the transition point of the Ising paramagnetic to antiferromagnetic quantum phase transition. The quench results in coherent oscillations for the orientation of effective Ising spins, detected via oscillations in the number of doubly occupied lattice sites. We characterize the quench by varying the system parameters. We report significant modification of the tunneling rate induced by interactions and show clear evidence for collective effects in the oscillatory response.

Photospheric oscillations. Pt. 1

International Nuclear Information System (INIS)

Fossat, E.; Ricort, G.

1975-01-01

Intensity fluctuations in the wings of the Fraunhofer line Na D 1 5896 have been recorded for about two hundred hours at the focus of the Nice coude refractor, using a sodium optical resonance device. Because of the large beam aperture available, records have been made on circular apertures from 22'' up to 32' diameter (the whole sun). The principal results from the analysis of these date are: As shown by White and Cha, the five-minute oscillation has a gaussian random character with a mean lifetime of about 20 min. Its two-dimensional spatial power spectrum is roughly gaussian for every temporal frequency between 2 and 6 MHz. The width of this gaussian spectrum is near 5 x 10 -5 km -1 (i.e. π = 20,000 km). (orig./BJ) [de

Numeric Simulation on the Performance of an Undulating Fin in the Wake of a Periodic Oscillating Plate

Directory of Open Access Journals (Sweden)

Zhang Yong-Hua

2013-10-01

Full Text Available A two-dimensional unsteady computational fluid dynamics (CFD method using an unstructured, grid-based and unsteady Navier-Stokes solver with automatic adaptive re-meshing to compute the unsteady flow was adopted to study the hydrodynamic interaction between a periodic oscillating plate and a rigid undulating fin in tandem arrangement. The user-defined function (UDF program was compiled to define the undulating and oscillating motion. First, the influence of the distance between the anterior oscillating plate and the posterior undulating fin on the non-dimensional drag coefficient of the fin was investigated. Ten different distances, D=0.2L, 0.4L, 0.6L, 0.8L, 1.0L, 1.2L, 1.4L, 1.6L, 1.8L and 2.0L, were considered. The performance of the fin for different distances (D is different. Second, the plate oscillating angle (5.7°, 10°, 20°, 30°, 40°, 45°, 50° and frequency (0.5 Hz, 1.0 Hz, 1.5 Hz, 2.0 Hz, 2.5 Hz, 3.0 Hz, 3.5 Hz, 4.0 Hz effects on the non-dimensional drag coefficient of the fin were also implemented. The pressure distribution on the fin was computed and integrated to provide fin forces, which were decomposed into lift and thrust. Meanwhile, the flow field was demonstrated and analysed. Based on the flow structures, the reasons for different undulating performances were discussed. It shows that the results largely depend on the distance between the two objects. The plate oscillating angle and frequency also make a certain contribution to the performance of the posterior undulating fin. The results are similar to the interaction between two undulating objects in tandem arrangement and they may provide a physical insight into the understanding of fin interaction in fishes or bio-robotic underwater propulsors that are propelled by multi fins.

Synchronization effects in two coupled one-dimensional lattices of phase oscillators

International Nuclear Information System (INIS)

Pando L, Carlos L.

2001-03-01

We study synchronization effects in a model consisting of two identical unidirectionally coupled 1-D arrays of phase oscillators. The master array is in the spatio-temporal chaos regime and the coupling across the two arrays is not strong enough in order to reach complete synchronization. The time series of the distance between the arrays is the main object of our study and this shows on-off intermittency. We can approximate the dynamics of the aforementioned time series with that of a first-order Markov process with two symbols. This model can be implemented in arrays of phase-locked loops (PPL) and Josephson junctions. (author)

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...

Radiofrequency-induced thermal therapy: results of a European multicentre study of resistive ablation of incompetent truncal varicose veins.

Science.gov (United States)

Braithwaite, B; Hnatek, L; Zierau, U; Camci, M; Akkersdijk, Gjm; Nio, D; Sarlija, M; Ajduk, M; Santoro, P; Roche, E

2013-02-01

To investigate the effectiveness of bipolar radiofrequency-induced thermal therapy (RFITT) in a multicentre non-randomized study. Some 672 incompetent saphenous veins (85% great saphenous varicose vein, 15% short saphenous vein) in 462 patients (56.5% CEAP [clinical, aetiological, anatomical and pathological elements] class 3 or worse) were treated in eight European centres. Patients were assessed between 180 and 360 days postoperatively. Occlusion rates were determined by duplex ultrasound and compared with the power used for treatment, pull back rate and experience of the operating surgeon. Complete occlusion rates of 98.4% were achieved when treatments were performed by an experienced operator (more than 20 cases), when the maximum power setting on the RFITT generator was between 18 and 20 W and the applicator was withdrawn at a rate slower than 1.5 second/cm RFITT is efficacious, well tolerated by patients and has a low incidence of procedure-related post-operative complications.

Trajectory generation to suppress oscillations in under-constrained cable-driven parallel robots

Energy Technology Data Exchange (ETDEWEB)

Hwang, Sung Wook; Bak, Jeong Hyeon; Yoon, Jong Hyun; Park, Jong Hyeon [Dept. of Mechanical Engineering, Hanyang University, Seoul (Korea, Republic of); Park, Jong Oh [School of Mechanical Engineering, Chonnam National University, Gwangju (Korea, Republic of)

2016-12-15

Cable-driven parallel robots (CDPRs) have many advantages over conventional link-based robot manipulators in terms of acceleration due to their low inertia. This paper concerns about under-constrained CDPRs, which have a less number of cables than six, often used favorably due to their simpler structures. Since a smaller number of cables than 6 are employed, however, their payloads have extra degrees of motion freedom and exhibit swaying motions or oscillation. In this paper, a scheme to suppress unwanted oscillatory motions of the payload of a 4-cable-driven CDPR based on a Zero-vibration (ZV) input-shaping scheme is proposed. In this method, a motion in the 3-dimensional space is projected onto the independent motions on two vertical planes perpendicular to each other. On each of the vertical plane, the natural frequency of the CDPR is computed based on a 2-cable-driven planar CDPR model. The precise dynamic model of a planar CDPR is obtained in order to find the natural frequency, which depends on the payload position. The advantage of the proposed scheme is that it is possible to generate an oscillation-free trajectory based on a ZV input-shaping scheme despite the complexity in the dynamics of the CDPR and the difficulty in computing the natural frequencies of the CDPR, which is required in any ZV input-shaping scheme. To verify the effectiveness of the proposed method, a series of computer simulations and experiments were conducted for 3- dimensional motions with a 4-cable-driven CDPR. Their results showed that the motions of the CDPR with the proposed method exhibited a significant reduction in oscillations of the payload. However, when the payload moves near the edges of its workspace, the improvement in oscillation reduction diminished as expected due to the errors in model projection.

Electroconvection in one-dimensional liquid crystal cells

Science.gov (United States)

Huh, Jong-Hoon

2018-04-01

We investigate the alternating current (ac) -driven electroconvection (EC) in one-dimensional cells (1DCs) under the in-plane switching mode. In 1DCs, defect-free EC can be realized. In the presence and absence of external multiplicative noise, the features of traveling waves (TWs), such as their Hopf frequency fH and velocity, are examined in comparison with those of conventional two-dimensional cells (2DCs) accompanying defects of EC rolls. In particular, we show that the defects significantly contribute to the features of the TWs. Additionally, owing to the defect-free EC in the 1DCs, the effects of the ac and noise fields on the TW are clarified. The ac field linearly increases fH, independent of the ac frequency f . The noise increases fH monotonically, but fH does not vary below a characteristic noise intensity VN*. In addition, soliton-like waves and unfamiliar oscillation of EC vortices in 1DCs are observed, in contrast to the localized EC (called worms) and the oscillation of EC rolls in 2DCs.

Size-sensitive particle trajectories in three-dimensional micro-bubble acoustic streaming flows

Science.gov (United States)

Volk, Andreas; Rossi, Massimiliano; Hilgenfeldt, Sascha; Rallabandi, Bhargav; Kähler, Christian; Marin, Alvaro

2015-11-01

Oscillating microbubbles generate steady streaming flows with interesting features and promising applications for microparticle manipulation. The flow around oscillating semi-cylindrical bubbles has been typically assumed to be independent of the axial coordinate. However, it has been recently revealed that particle motion is strongly three-dimensional: Small tracer particles follow vortical trajectories with pronounced axial displacements near the bubble, weaving a toroidal stream-surface. A well-known consequence of bubble streaming flows is size-dependent particle migration, which can be exploited for sorting and trapping of microparticles in microfluidic devices. In this talk, we will show how the three-dimensional toroidal topology found for small tracer particles is modified as the particle size increases up to 1/3 of the bubble radius. Our results show size-sensitive particle positioning along the axis of the semi-cylindrical bubble. In order to analyze the three-dimensional sorting and trapping capabilities of the system, experiments with an imposed flow and polydisperse particle solutions are also shown.

The quantum oscillator on complex projective space (Lobachewski space) in a constant magnetic field and the issue of generic boundary conditions

International Nuclear Information System (INIS)

Giri, Pulak Ranjan

2007-01-01

We perform a one-parameter family of self-adjoint extensions characterized by the parameter ω 0 . This allows us to get generic boundary conditions for the quantum oscillator on N-dimensional complex projective space (CP N ) and on its non-compact version, i.e., Lobachewski space (L N ) in the presence of a constant magnetic field. As a result, we get a family of energy spectra for the oscillator. In our formulation the already known result of this oscillator also belongs to the family. We have also obtained an energy spectrum which preserves all the symmetries (full-hidden symmetry and rotational symmetry) of the oscillator. The method of self-adjoint extensions has also been discussed for a conic oscillator in the presence of the constant magnetic field

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 ?...

On the quantisation of one-dimensional bags

International Nuclear Information System (INIS)

Fairley, G.T.; Squires, E.J.

1976-01-01

The quantisation of one-dimensional MIT bags by expanding the fields as a sum of classical modes and truncating the series after the first term is discussed. The lowest states of a bag in a world containing two scalar quark fields are obtained. Problems associated with the zero-point oscillations of the field are discussed. (Auth.)

The anisosphere as a new tool for interpreting Foucault pendulum experiments. Part I: harmonic oscillators

Science.gov (United States)

Verreault, René

2017-08-01

In an attempt to explain the tendency of Foucault pendula to develop elliptical orbits, Kamerlingh Onnes derived equations of motion that suggest the use of great circles on a spherical surface as a graphical illustration for an anisotropic bi-dimensional harmonic oscillator, although he did not himself exploit the idea any further. The concept of anisosphere is introduced in this work as a new means of interpreting pendulum motion. It can be generalized to the case of any two-dimensional (2-D) oscillating system, linear or nonlinear, including the case where coupling between the 2 degrees of freedom is present. Earlier pendulum experiments in the literature are revisited and reanalyzed as a test for the anisosphere approach. While that graphical method can be applied to strongly nonlinear cases with great simplicity, this part I is illustrated through a revisit of Kamerlingh Onnes' dissertation, where a high performance pendulum skillfully emulates a 2-D harmonic oscillator. Anisotropy due to damping is also described. A novel experiment strategy based on the anisosphere approach is proposed. Finally, recent original results with a long pendulum using an electronic recording alidade are presented. A gain in precision over traditional methods by 2-3 orders of magnitude is achieved.

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.

Higher-Dimensional Solitons Stabilized by Opposite Charge

CERN Document Server

Binder, B

2002-01-01

In this paper it is shown how higher-dimensional solitons can be stabilized by a topological phase gradient, a field-induced shift in effective dimensionality. As a prototype, two instable 2-dimensional radial symmetric Sine-Gordon extensions (pulsons) are coupled by a sink/source term such, that one becomes a stable 1d and the other a 3d wave equation. The corresponding physical process is identified as a polarization that fits perfectly to preliminary considerations regarding the nature of electric charge and background of 1/137. The coupling is iterative with convergence limit and bifurcation at high charge. It is driven by the topological phase gradient or non-local Gauge potential that can be mapped to a local oscillator potential under PSL(2,R).

Restoration of oscillation in network of oscillators in presence of direct and indirect interactions

Energy Technology Data Exchange (ETDEWEB)

Majhi, Soumen; Bera, Bidesh K. [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India); Bhowmick, Sourav K. [Department of Electronics, Asutosh College, Kolkata-700026 (India); Ghosh, Dibakar, E-mail: diba.ghosh@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India)

2016-10-23

The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau–Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators. - Highlights: • Amplitude death is observed using direct and indirect coupling. • Revival of oscillation using feedback parameter is discussed. • Restoration of oscillation is observed in limit cycle and chaotic systems.

Numerical simulation of electron beam welding with beam oscillations

Science.gov (United States)

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.

Three dimensional (3d) transverse oscillation vector velocity ultrasound imaging

DEFF Research Database (Denmark)

2013-01-01

as to traverse a field of view, and receive circuitry (306) configured to receive a two dimensional set of echoes produced in response to the ultrasound signal traversing structure in the field of view, wherein the structure includes flowing structures such as flowing blood cells, organ cells etc. A beamformer...

Nonlinear response of a forced van der Pol-Duffing oscillator at non-resonant bifurcations of codimension two

International Nuclear Information System (INIS)

Ji, J.C.; Zhang, N.

2009-01-01

Non-resonant bifurcations of codimension two may appear in the controlled van der Pol-Duffing oscillator when two critical time delays corresponding to a double Hopf bifurcation have the same value. With the aid of centre manifold theorem and the method of multiple scales, the non-resonant response and two types of primary resonances of the forced van der Pol-Duffing oscillator at non-resonant bifurcations of codimension two are investigated by studying the possible solutions and their stability of the four-dimensional ordinary differential equations on the centre manifold. It is shown that the non-resonant response of the forced oscillator may exhibit quasi-periodic motions on a two- or three-dimensional (2D or 3D) torus. The primary resonant responses admit single and mixed solutions and may exhibit periodic motions or quasi-periodic motions on a 2D torus. Illustrative examples are presented to interpret the dynamics of the controlled system in terms of two dummy unfolding parameters and exemplify the periodic and quasi-periodic motions. The analytical predictions are found to be in good agreement with the results of numerical integration of the original delay differential equation.

Oscillations of void lattices

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

Patterns of patterns of synchronization: Noise induced attractor switching in rings of coupled nonlinear oscillators

Energy Technology Data Exchange (ETDEWEB)

Emenheiser, Jeffrey [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Chapman, Airlie; Mesbahi, Mehran [William E. Boeing Department of Aeronautics and Astronautics, University of Washington, Seattle, Washington 98195 (United States); Pósfai, Márton [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Crutchfield, James P. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Physics, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); D' Souza, Raissa M. [Complexity Sciences Center, University of California, Davis, California 95616 (United States); Department of Computer Science, University of California, Davis, California 95616 (United States); Santa Fe Institute, Santa Fe, New Mexico 87501 (United States); Department of Mechanical and Aerospace Engineering, University of California, Davis, California 95616 (United States)

2016-09-15

Following the long-lived qualitative-dynamics tradition of explaining behavior in complex systems via the architecture of their attractors and basins, we investigate the patterns of switching between distinct trajectories in a network of synchronized oscillators. Our system, consisting of nonlinear amplitude-phase oscillators arranged in a ring topology with reactive nearest-neighbor coupling, is simple and connects directly to experimental realizations. We seek to understand how the multiple stable synchronized states connect to each other in state space by applying Gaussian white noise to each of the oscillators' phases. To do this, we first analytically identify a set of locally stable limit cycles at any given coupling strength. For each of these attracting states, we analyze the effect of weak noise via the covariance matrix of deviations around those attractors. We then explore the noise-induced attractor switching behavior via numerical investigations. For a ring of three oscillators, we find that an attractor-switching event is always accompanied by the crossing of two adjacent oscillators' phases. For larger numbers of oscillators, we find that the distribution of times required to stochastically leave a given state falls off exponentially, and we build an attractor switching network out of the destination states as a coarse-grained description of the high-dimensional attractor-basin architecture.

Global solubility of the three-dimensional Navier-Stokes equations with uniformly large initial vorticity

International Nuclear Information System (INIS)

Makhalov, A S; Nikolaenko, V P

2003-01-01

This paper is a survey of results concerning the three-dimensional Navier-Stokes and Euler equations with initial data characterized by uniformly large vorticity. The existence of regular solutions of the three-dimensional Navier-Stokes equations on an unbounded time interval is proved for large initial data both in R 3 and in bounded cylindrical domains. Moreover, the existence of smooth solutions on large finite time intervals is established for the three-dimensional Euler equations. These results are obtained without additional assumptions on the behaviour of solutions for t>0. Any smooth solution is not close to any two-dimensional manifold. Our approach is based on the computation of singular limits of rapidly oscillating operators, non-linear averaging, and a consideration of the mutual absorption of non-linear oscillations of the vorticity field. The use of resonance conditions, methods from the theory of small divisors, and non-linear averaging of almost periodic functions leads to the limit resonant Navier-Stokes equations. Global solubility of these equations is proved without any conditions on the three-dimensional initial data. The global regularity of weak solutions of three-dimensional Navier-Stokes equations with uniformly large vorticity at t=0 is proved by using the regularity of weak solutions and the strong convergence

Vibrational spectra and thermal rectification in three-dimensional anharmonic lattices

International Nuclear Information System (INIS)

Lan Jinghua; Li Baowen

2007-01-01

We study thermal rectification in a three-dimensional model consisting of two segments of anharmonic lattices. One segment consists of layers of harmonic oscillator arrays coupled to a substrate potential, which is a three-dimensional Frenkel-Kontorova model, and the other segment is a three-dimensional Fermi-Pasta-Ulam model. We study the vibrational bands of the two lattices analytically and numerically, and find that, by choosing the system parameters properly, the rectification can be as high as a few thousands, which is high enough to be observed in experiment. Possible experiments in nanostructures are discussed

Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits

KAUST Repository

Ge, Xiaoqing

2010-12-01

Hassan Khalil’s research results and beautifully written textbook on nonlinear systems have influenced generations of researchers, including the authors of this paper. Using nonlinear systems techniques, this paper analyzes ring oscillator and cross-coupled oscillator circuits, which are essential building blocks in digital systems. The paper first investigates local and global stability properties of an n-stage ring oscillator by making use of its cyclic structure. It next studies global stability properties of a class of cross-coupled oscillators which admit the representation of a dynamic system in feedback with a static nonlinearity, and presents su cient conditions for almost global convergence of the solutions to a limit cycle when the feedback gain is in the vicinity of a bifurcation point. The result are also extended to the synchronization of interconnected identical oscillator circuits.

Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits

KAUST Repository

Ge, Xiaoqing; Arcak, Murat; Salama, Khaled N.

2010-01-01

Hassan Khalil’s research results and beautifully written textbook on nonlinear systems have influenced generations of researchers, including the authors of this paper. Using nonlinear systems techniques, this paper analyzes ring oscillator and cross-coupled oscillator circuits, which are essential building blocks in digital systems. The paper first investigates local and global stability properties of an n-stage ring oscillator by making use of its cyclic structure. It next studies global stability properties of a class of cross-coupled oscillators which admit the representation of a dynamic system in feedback with a static nonlinearity, and presents su cient conditions for almost global convergence of the solutions to a limit cycle when the feedback gain is in the vicinity of a bifurcation point. The result are also extended to the synchronization of interconnected identical oscillator circuits.

Oscillations in the dark energy equation of state: New MCMC lessons

International Nuclear Information System (INIS)

Lazkoz, Ruth; Salzano, Vincenzo; Sendra, Irene

2010-01-01

We study the possibility of detecting oscillating patterns in the equation of state (EoS) of the dark energy using different cosmological datasets. We follow a phenomenological approach and study three different oscillating models for the EoS, one of them periodic and the other two damped (proposed here for the first time). All the models are characterized by the amplitude, the center and the frequency of oscillations. In contrast to previous works in the literature, we do not fix the frequency to a fiducial value related to the time extension of chosen datasets, but consider a discrete set of values, so to avoid arbitrariness and try to detect any possible time period in the EoS. We test the models using a recent collection of SNeIa, direct Hubble data and Gamma Ray Bursts data. Main results are: I. even if constraints on the amplitude are not too strong, we detect a trend of it versus the frequency, i.e. decreasing (and even negatives) amplitudes for higher frequencies; II. the center of oscillation (which corresponds to the present value of the EoS parameter) is very well constrained, and phantom behavior seems statistically disfavored; III. the frequency is hard to constrain, showing similar statistical validity for all the values of the discrete set chosen, but the best fit of all the considered scenarios is associated with a period which is in the redshift range depicted by our cosmological data. The 'best' oscillating models are compared with ΛCDM using different dimensionally consistent and Bayesian-based information criteria; the conclusion is reached that at present, data cannot discriminate between a cosmological constant and oscillating equation of state.

Oscillations of disks

CERN Document Server

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...

Self-oscillation in spin torque oscillator stabilized by field-like torque

International Nuclear Information System (INIS)

Taniguchi, Tomohiro; Tsunegi, Sumito; Kubota, Hitoshi; Imamura, Hiroshi

2014-01-01

The effect of the field-like torque on the self-oscillation of the magnetization in spin torque oscillator with a perpendicularly magnetized free layer was studied theoretically. A stable self-oscillation at zero field is excited for negative β while the magnetization dynamics stops for β = 0 or β > 0, where β is the ratio between the spin torque and the field-like torque. The reason why only the negative β induces the self-oscillation was explained from the view point of the energy balance between the spin torque and the damping. The oscillation power and frequency for various β were also studied by numerical simulation

Four-cluster chimera state in non-locally coupled phase oscillator systems with an external potential

International Nuclear Information System (INIS)

Zhu Yun; Zheng Zhi-Gang; Yang Jun-Zhong

2013-01-01

Dynamics of a one-dimensional array of non-locally coupled Kuramoto phase oscillators with an external potential is studied. A four-cluster chimera state is observed for the moderate strength of the external potential. Different from the clustered chimera states studied before, the instantaneous frequencies of the oscillators in a synchronized cluster are different in the presence of the external potential. As the strength of the external potential increases, a bifurcation from the two-cluster chimera state to the four-cluster chimera states can be found. These phenomena are well predicted analytically with the help of the Ott—Antonsen ansatz. (general)

Competition for synchronization in a phase oscillator system

Science.gov (United States)

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.

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

Approximation of sums of oscillating summands in certain physical problems

International Nuclear Information System (INIS)

Karatsuba, Ekatherina A.

2004-01-01

The motion of a one-dimensional harmonic oscillator caused by recurring pushes in the absence of friction is considered. In particular, two cases are studied: the case when the pushes become more frequent and the other one when the pushes become less frequent. By means of an application of the Hardy-Littlewood-Vinogradov-Van der Corput theorem on the approximation of exponential sums by shorter ones, new asymptotic formulas for the solution of the problem are obtained

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.

κ-deformed Dirac oscillator in an external magnetic field

Science.gov (United States)

Chargui, Y.; Dhahbi, A.; Cherif, B.

2018-04-01

We study the solutions of the (2 + 1)-dimensional κ-deformed Dirac oscillator in the presence of a constant transverse magnetic field. We demonstrate how the deformation parameter affects the energy eigenvalues of the system and the corresponding eigenfunctions. Our findings suggest that this system could be used to detect experimentally the effect of the deformation. We also show that the hidden supersymmetry of the non-deformed system reduces to a hidden pseudo-supersymmetry having the same algebraic structure as a result of the κ-deformation.

Using harmonic oscillators to determine the spot size of Hermite-Gaussian laser beams

Science.gov (United States)

Steely, Sidney L.

1993-01-01

The similarity of the functional forms of quantum mechanical harmonic oscillators and the modes of Hermite-Gaussian laser beams is illustrated. This functional similarity provides a direct correlation to investigate the spot size of large-order mode Hermite-Gaussian laser beams. The classical limits of a corresponding two-dimensional harmonic oscillator provide a definition of the spot size of Hermite-Gaussian laser beams. The classical limits of the harmonic oscillator provide integration limits for the photon probability densities of the laser beam modes to determine the fraction of photons detected therein. Mathematica is used to integrate the probability densities for large-order beam modes and to illustrate the functional similarities. The probabilities of detecting photons within the classical limits of Hermite-Gaussian laser beams asymptotically approach unity in the limit of large-order modes, in agreement with the Correspondence Principle. The classical limits for large-order modes include all of the nodes for Hermite Gaussian laser beams; Sturm's theorem provides a direct proof.

Numerical study on optimal Stirling engine regenerator matrix designs taking into account the effects of matrix temperature oscillations

DEFF Research Database (Denmark)

Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove

2006-01-01

A new regenerator matrix design that improves the efficiency of a Stirling engine has been developed in a numerical study of the existing SM5 Stirling engine. A new, detailed, one-dimensional Stirling engine model that delivers results in good agreement with experimental data was used for mapping...... the per- formance of the engine, for mapping the effects of regenerator matrix temperature oscillations, and for optimising the regenerator design. The regenerator matrix temperatures were found to oscillate in two modes. The first mode was oscillation of a nearly linear axial matrix temperature profile...... while the second mode bended the ends of the axial matrix temperature profile when gas flowed into the regenerator with a temperature significantly different from the matrix temperature. The first mode of oscillation improved the efficiency of the engine but the second mode reduced both the work output...

Suppression and revival of oscillation in indirectly coupled limit cycle oscillators

International Nuclear Information System (INIS)

Sharma, P.R.; Kamal, N.K.; Verma, U.K.; Suresh, K.; Thamilmaran, K.; Shrimali, M.D.

2016-01-01

Highlights: • The phenomena of suppression and revival of oscillations are studied in indirectly coupled nonlinear oscillators. • The decay parameter and a feedback factor play a crucial role in emergent dynamical behavior of oscillators. • The critical curves for different dynamical regions are obtained analytically using linear stability analysis. • Electronic circuit experiments demonstrate these emergent dynamical states. - Abstract: We study the phenomena of suppression and revival of oscillations in a system of limit cycle oscillators coupled indirectly via a dynamic local environment. The dynamics of the environment is assumed to decay exponentially with time. We show that for appropriate coupling strength, the decay parameter of the environment plays a crucial role in the emergent dynamics such as amplitude death (AD) and oscillation death (OD). We also show that introducing a feedback factor in the diffusion term revives the oscillations in this system. The critical curves for the regions of different emergent states as a function of coupling strength, decay parameter of the environment and feedback factor in the coupling are obtained analytically using linear stability analysis. These results are found to be consistent with the numerics and are also observed experimentally.

Non-unique monopole oscillations of harmonically confined Yukawa systems

Science.gov (United States)

Ducatman, Samuel; Henning, Christian; Kaehlert, Hanno; Bonitz, Michael

2008-11-01

Recently it was shown that the Breathing Mode (BM), the mode of uniform radial expansion and contraction, which is well known from harmonically confined Coulomb systems [1], does not exist in general for other systems [2]. As a consequence the monopole oscillation (MO), the radial collective excitation, is not unique, but there are several MO with different frequencies. Within this work we show simulation results of those monopole oscillations of 2-dimensional harmonically confined Yukawa systems, which are known from, e.g., dusty plasma crystals [3,4]. We present the corresponding spectrum of the particle motion, including analysis of the frequencies found, and compare with theoretical investigations.[1] D.H.E. Dubin and J.P. Schiffer, Phys. Rev. E 53, 5249 (1996)[2] C. Henning at al., accepted for publication in Phys. Rev. Lett. (2008)[3] A. Melzer et al., Phys. Rev. Lett. 87, 115002 (2001)[4] M. Bonitz et al., Phys. Rev. Lett. 96, 075001 (2006)

Quasi-periodic Oscillations in Flares and Coronal Mass Ejections Associated with Magnetic Reconnection

Energy Technology Data Exchange (ETDEWEB)

Takahashi, Takuya; Shibata, Kazunari [Kwasan and Hida Observatories, Kyoto University, Yamashina, Kyoto 607-8471 (Japan); Qiu, Jiong, E-mail: takahasi@kusastro.kyoto-u.ac.jp [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States)

2017-10-20

We propose a mechanism for quasi-periodic oscillations of both coronal mass ejections (CMEs) and flare loops as related to magnetic reconnection in eruptive solar flares. We perform two-dimensional numerical MHD simulations of magnetic flux rope eruption, with three different values of the global Lundquist number. In the low Lundquist number run, no oscillatory behavior is found. In the moderate Lundquist number run, on the other hand, quasi-periodic oscillations are excited both at the bottom of the flux rope and at the flare loop top. In the high Lundquist number run, quasi-periodic oscillations are also excited; in the meanwhile, the dynamics become turbulent owing to the formation of multiple plasmoids in the reconnection current sheet. In high and moderate Lundquist number runs, thin reconnection jets collide with the flux rope bottom or flare loop top and dig them deeply. Steep oblique shocks are formed as termination shocks where reconnection jets are bent (rather than decelerated) in the horizontal direction, resulting in supersonic backflows. The structure becomes unstable, and quasi-periodic oscillations of supersonic backflows appear at locally confined high-beta regions at both the flux rope bottom and flare loop top. We compare the observational characteristics of quasi-periodic oscillations in erupting flux ropes, post-CME current sheets, flare ribbons, and light curves with corresponding dynamical structures found in our simulation.

Lattice Boltzmann simulation of the convective heat transfer from a stream-wise oscillating circular cylinder

International Nuclear Information System (INIS)

Bao Sheng; Chen Sheng; Liu Zhaohui; Zheng Chuguang

2012-01-01

Highlights: ► Heat transfer is enhanced by small and slow stream-wise oscillation. ► The average Nu decreases with increasing oscillation frequency. ► The RMS Nu increases with increasing frequency. ► The mean and RMS Nu reach a local maximum value in locked regime. ► Similar frequency effect is found for different Reynolds numbers. - Abstract: In this paper, we studied the convective heat transfer from a stream-wise oscillating circular cylinder. Two dimensional numerical simulations are conducted at Re = 100–200, A = 0.1–0.4 and F = f o /f s = 0.2–3.0 with the aid of the lattice Boltzmann method. In particular, detailed attentions are paid on the extensive numerical results elucidating the influence of oscillation frequency, oscillation amplitude and Reynolds number on the time-average and RMS value of the Nusselt number. Over the ranges of conditions considered herein, the heat transfer characteristics are observed to be influenced in an intricate manner by the value of the oscillation frequency (F), oscillation amplitude (A) and Reynolds number (Re). Firstly, the heat transfer is enhanced when the cylinder oscillates stream-wise with small amplitude and low frequency, while it will be reduced by large amplitude and high frequency. Secondly, the average Nusselt number (Nu (ave)) decreases against the increasing value of oscillation frequency, while the RMS value of the Nusselt number, Nu (RMS), displays an opposite trend. Third, we obtained a similar frequency effect on the heat transfer over the range of Reynolds numbers investigated in this paper. In addition, detailed analyses on phase portraits, energy spectrum are also made.

Clinical effectiveness and cost-effectiveness of foam sclerotherapy, endovenous laser ablation and surgery for varicose veins: results from the Comparison of LAser, Surgery and foam Sclerotherapy (CLASS) randomised controlled trial.

Science.gov (United States)

Brittenden, Julie; Cotton, Seonaidh C; Elders, Andrew; Tassie, Emma; Scotland, Graham; Ramsay, Craig R; Norrie, John; Burr, Jennifer; Francis, Jill; Wileman, Samantha; Campbell, Bruce; Bachoo, Paul; Chetter, Ian; Gough, Michael; Earnshaw, Jonothan; Lees, Tim; Scott, Julian; Baker, Sara A; MacLennan, Graeme; Prior, Maria; Bolsover, Denise; Campbell, Marion K

2015-01-01

BACKGROUND Foam sclerotherapy (foam) and endovenous laser ablation (EVLA) have emerged as alternative treatments to surgery for patients with varicose veins, but uncertainty exists regarding their effectiveness in the medium to longer term. OBJECTIVES To assess the clinical effectiveness and cost-effectiveness of foam, EVLA and surgery for the treatment of varicose veins. DESIGN A parallel-group randomised controlled trial (RCT) without blinding, and economic modelling evaluation. SETTING Eleven UK specialist vascular centres. PARTICIPANTS Seven hundred and ninety-eight patients with primary varicose veins (foam, n = 292; surgery, n = 294; EVLA, n = 212). INTERVENTIONS Patients were randomised between all three treatment options (eight centres) or between foam and surgery (three centres). PRIMARY OUTCOME MEASURES Disease-specific [Aberdeen Varicose Vein Questionnaire (AVVQ)] and generic [European Quality of Life-5 Dimensions (EQ-5D), Short Form questionnaire-36 items (SF-36) physical and mental component scores] quality of life (QoL) at 6 months. Cost-effectiveness as cost per quality-adjusted life-year (QALY) gained. SECONDARY OUTCOME MEASURES Quality of life at 6 weeks; residual varicose veins; Venous Clinical Severity Score (VCSS); complication rates; return to normal activity; truncal vein ablation rates; and costs. RESULTS The results appear generalisable in that participants' baseline characteristics (apart from a lower-than-expected proportion of females) and post-treatment improvement in outcomes were comparable with those in other RCTs. The health gain achieved in the AVVQ with foam was significantly lower than with surgery at 6 months [effect size -1.74, 95% confidence interval (CI) -2.97 to -0.50; p = 0.006], but was similar to that achieved with EVLA. The health gain in SF-36 mental component score for foam was worse than that for EVLA (effect size 1.54, 95% CI 0.01 to 3.06; p = 0.048) but similar to that for surgery. There were no

The Oscillator Principle of Nature

DEFF Research Database (Denmark)

Lindberg, Erik

2012-01-01

Oscillators are found on all levels in Nature. The general oscillator concept is defined and investigated. Oscillators may synchronize into fractal patterns. Apparently oscillators are the basic principle in Nature. The concepts of zero and infinite are discussed. Electronic manmade oscillators...

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

Science.gov (United States)

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.

Bipolaron assisted Bloch-like oscillations in organic lattices

Energy Technology Data Exchange (ETDEWEB)

Ribeiro, Luiz Antonio, E-mail: ribeirojr@unb.br [International Center for Condensed Matter Physics, University of Brasília, P.O. Box 04531, 70.919-970, Brasília, DF (Brazil); University of Brasília, UnB Faculty of Planaltina, 73.345-010, Planaltina, DF (Brazil); Ferreira da Cunha, Wiliam; Magela e Silva, Geraldo [Institute of Physics, University of Brasília, 70.919-970, Brasília (Brazil)

2017-06-15

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.

Gas dynamics models for an oscillating gaseous core fission reactor

Energy Technology Data Exchange (ETDEWEB)

Kuijper, J.C.; Dam, H. van; Hoogenboom, J.E. (Interuniversitair Reactor Inst., Delft (Netherlands))

1991-01-01

Two one-dimensional models are developed for the investigation of the gas dynamical behaviour of the fuel gas in a cylindrical gaseous core fission reactor. By numerical and analytical calculations, it is shown that, for the case where a direct energy extraction mechanism (such as magneto-hydrodynamics (MHD)) is not present, increasing density oscillations occur in the gas. Also an estimate is made of the attainable direct energy conversion efficiency, for the case where a direct energy extraction mechanism is present. (author).

Commensurability oscillations in a quasi-two-dimensional electron gas subject to strong in-plane magnetic field

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

Xenon spatial oscillation in nuclear power reactors:an analytical approach through non linear modal analysis

International Nuclear Information System (INIS)

Suarez Antola, R.

2005-01-01

It was proponed recently to apply an extension of Lyapunov's first method to the non-linear regime, known as non-linear modal analysis (NMA), to the study of space-time problems in nuclear reactor kinetics, nuclear power plant dynamics and nuclear power plant instrumentation and control(1). The present communication shows how to apply NMA to the study of Xenon spatial oscillations in large nuclear reactors. The set of non-linear modal equations derived by J. Lewins(2) for neutron flux, Xenon concentration and Iodine concentration are discussed, and a modified version of these equations is taken as a starting point. Using the methods of singular perturbation theory a slow manifold is constructed in the space of mode amplitudes. This allows the reduction of the original high dimensional dynamics to a low dimensional one. It is shown how the amplitudes of the first mode for neutron flux field, temperature field and concentrations of Xenon and Iodine fields can have a stable steady state value while the corresponding amplitudes of the second mode oscillates in a stable limit cycle. The extrapolated dimensions of the reactor's core are used as bifurcation parameters. Approximate analytical formulae are obtained for the critical values of this parameters( below which the onset of oscillations is produced), for the period and for the amplitudes of the above mentioned oscillations. These results are applied to the discussion of neutron flux and temperature excursions in critical locations of the reactor's core. The results of NMA can be validated from the results obtained applying suitable computer codes, using homogenization theory(3) to link the complex heterogeneous model of the codes with the simplified mathematical model used for NMA

Magnetron injection gun for a broadband gyrotron backward-wave oscillator

International Nuclear Information System (INIS)

Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

2009-01-01

The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio (α) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant α will be discussed in depth.

Magnetron injection gun for a broadband gyrotron backward-wave oscillator

Science.gov (United States)

Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

2009-07-01

The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio (α) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant α will be discussed in depth.

Are the North Atlantic oscillation and the southern oscillation related in any time-scale?

Energy Technology Data Exchange (ETDEWEB)

Garcia, R.; Ribera, P.; Hernandez, E. [Universidad Complutense de Madrid (Spain). Facultad de Ciencias Fisicas; Gimenoo, L. [Fac. Ciencias, Univ. Vigo, Ourense (Spain)

2000-02-01

The north Atlantic oscillation (NAO) and the southern oscillation (SO) are compared from the standpoint of a possible common temporal scale of oscillation. To do this a cross-spectrum of the temporal series of NAO and SO indices was determined, finding a significant common oscillation of 6-8 years. To assure this finding, both series were decomposed in their main oscillations using singular spectrum analysis (SSA). Resulting reconstructed series of 6-8 years' oscillation were then cross-correlated without and with pre-whitened, the latter being significant. The main conclusion is a possible relationship between a common oscillation of 6-8 years that represents about 20% of the SO variance and about 25% of the NAO variance. (orig.)

Automatic Oscillating Turret.

Science.gov (United States)

1981-03-01

Final Report: February 1978 ZAUTOMATIC OSCILLATING TURRET SYSTEM September 1980 * 6. PERFORMING 01G. REPORT NUMBER .J7. AUTHOR(S) S. CONTRACT OR GRANT...o....e.... *24 APPENDIX P-4 OSCILLATING BUMPER TURRET ...................... 25 A. DESCRIPTION 1. Turret Controls ...Other criteria requirements were: 1. Turret controls inside cab. 2. Automatic oscillation with fixed elevation to range from 20* below the horizontal to

Inverted oscillator

Energy Technology Data Exchange (ETDEWEB)

Yuce, C [Physics Department, Anadolu University, Eskisehir (Turkey); Kilic, A [Physics Department, Anadolu University, Eskisehir (Turkey); Coruh, A [Physics Department, Sakarya University, Sakarya (Turkey)

2006-07-15

The inverted harmonic oscillator problem is investigated quantum mechanically. The exact wavefunction for the confined inverted oscillator is obtained and it is shown that the associated energy eigenvalues are discrete, and the energy is given as a linear function of the quantum number n.

Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

International Nuclear Information System (INIS)

Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G.

1995-01-01

Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author)

Reactor oscillator - Proposal of the organisation for oscillator operation; Reaktorski oscilator - Predlog organizacije rada na oscilatoru

Energy Technology Data Exchange (ETDEWEB)

Lolic, B; Loloc, B [Institute of Nuclear Sciences Boris Kidric, Laboratorija za fiziku reaktora, Vinca, Beograd (Serbia and Montenegro)

1961-12-15

The organizational structure for operating the reactor with the reactor oscillator describes the duties of the reactor operators; staff responsible for operating the oscillator who are responsible for measurements, preparation of the samples and further treatment of the obtained results.

Experimental demonstration of revival of oscillations from death in coupled nonlinear oscillators

Energy Technology Data Exchange (ETDEWEB)

Senthilkumar, D. V., E-mail: skumarusnld@gmail.com [School of Physics, Indian Institute of Science Education and Research, Thiruvananthapuram 695016 (India); Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401 (India); Suresh, K. [Department of Physics, Anjalai Ammal-Engineering College, Kovilvenni 614 403, Tamilnadu (India); Centre for Nonlinear Dynamics, Bharathidasan University, Trichy 620024, Tamilnadu (India); Chandrasekar, V. K. [Centre for Nonlinear Science and Engineering, School of Electrical and Electronics Engineering, SASTRA University, Thanjavur 613 401 (India); Zou, Wei [School of Mathematics and Statistics, Huazhong University of Science and Technology, Wuhan 430074 (China); Centre for Mathematical Sciences, Huazhong University of Science and Technology, Wuhan 430074 (China); Dana, Syamal K. [CSIR-Indian Institute of Chemical Biology, Kolkata 700032 (India); Kathamuthu, Thamilmaran [Centre for Nonlinear Dynamics, Bharathidasan University, Trichy 620024, Tamilnadu (India); Kurths, Jürgen [Potsdam Institute for Climate Impact Research, Telegrafenberg, Potsdam D-14415 (Germany); Institute of Physics, Humboldt University Berlin, Berlin D-12489 (Germany); Institute for Complex Systems and Mathematical Biology, University of Aberdeen, Aberdeen AB24 3FX (United Kingdom); Department of Control Theory, Nizhny Novgorod State University, Gagarin Avenue 23, 606950 Nizhny Novgorod (Russian Federation)

2016-04-15

We experimentally demonstrate that a processing delay, a finite response time, in the coupling can revoke the stability of the stable steady states, thereby facilitating the revival of oscillations in the same parameter space where the coupled oscillators suffered the quenching of oscillation. This phenomenon of reviving of oscillations is demonstrated using two different prototype electronic circuits. Further, the analytical critical curves corroborate that the spread of the parameter space with stable steady state is diminished continuously by increasing the processing delay. Finally, the death state is completely wiped off above a threshold value by switching the stability of the stable steady state to retrieve sustained oscillations in the same parameter space. The underlying dynamical mechanism responsible for the decrease in the spread of the stable steady states and the eventual reviving of oscillation as a function of the processing delay is explained using analytical results.

Oscillations, complex spatiotemporal behavior, and information transport in networks of excitatory and inhibitory neurons

International Nuclear Information System (INIS)

Destexhe, A.

1994-01-01

Various types of spatiotemporal behavior are described for two-dimensional networks of excitatory and inhibitory neurons with time delayed interactions. It is described how the network behaves as several structural parameters are varied, such as the number of neurons, the connectivity, and the values of synaptic weights. A transition from spatially uniform oscillations to spatiotemporal chaos via intermittentlike behavior is observed. The properties of spatiotemporally chaotic solutions are investigated by evaluating the largest positive Lyapunov exponent and the loss of correlation with distance. Finally, properties of information transport are evaluated during uniform oscillations and spatiotemporal chaos. It is shown that the diffusion coefficient increases significantly in the spatiotemporal phase similar to the increase of transport coefficients at the onset of fluid turbulence. It is proposed that such a property should be seen in other media, such as chemical turbulence or networks of oscillators. The possibility of measuring information transport from appropriate experiments is also discussed

Clinical and biochemical manifestations of undifferentiated forms of connective tissue dysplasia in pregnant women with varicose veins of small pelvis

Directory of Open Access Journals (Sweden)

N.M. Shibelgut

2010-03-01

Full Text Available Research objective is to define the pathogenesis of varicous veins of small pelvis in women. at Ultrasonic investigation of venous system of small pelvis has been carried out in 290 pregnant women. It revealed 190 patients with varicose veins of small pelvis (VVSP. By means of V.M. Jakovleva's technique phenotypic menifestation of connective tissue dysplasia was determined in all pregnant women. Biochemical manifestations of connective tissue dysplasia were identified by sialic acid level in blood serum, daily excretion of glycosaminoglycans and oxyproline. High frequency of clinical and biochemical manifestations of undifferentiated forms of connective tissue dysplasia was revealed in pregnant women with VVSP. Patients with VVSP developed tooth and jaw, facial and locomotor damages. Patients with VVSP characterized by visceral undifferentiated forms of connective tissue dysplasia demonstrated by refraction involvement, ventral hernias, flat feet, varicous veins of lower extremities, hypermobile syndrome, mitral valve prolapse of different degree. Biochemical manifestations of undifferentiated forms of connective tissue dysplasia in pregnant women with VVSP were insignificant

Nonlinear dynamics in a trapped atomic Bose-Einstein condensate induced by an oscillating Gaussian potential

International Nuclear Information System (INIS)

Fujimoto, Kazuya; Tsubota, Makoto

2011-01-01

We consider a trapped atomic Bose-Einstein condensate penetrated by a repulsive Gaussian potential and theoretically investigate the dynamics induced by oscillating the Gaussian potential. Our study is based on the numerical calculation of the two-dimensional Gross-Pitaevskii equation. Our calculation reveals the dependence of the characteristic behavior of the condensate on the amplitude and frequency of the oscillating potential. These dynamics are deeply related to the nucleation and dynamics of quantized vortices and solitons. When the potential oscillates with a large amplitude, it nucleates many vortex pairs that move away from the potential. When the amplitude of the oscillation is small, it nucleates solitons through an annihilation of vortex pairs. We discuss three issues concerning the nucleation of vortices. The first is the phase diagram for the nucleation of vortices and solitons near the oscillating potential. The second is the mechanism and critical velocity of the nucleation. The critical velocity of the nucleation is an important issue in quantum fluids, and we propose an expression for the velocity containing both the coherence length and the size of the potential. The third is the divergence of the nucleation time, which is the time it takes for the potential to nucleate vortices, near the critical parameters for vortex nucleation.

Chromospheric oscillations

NARCIS (Netherlands)

Lites, B.W.; Rutten, R.J.; Thomas, J.H.

1995-01-01

We show results from SO/Sacramento Peak data to discuss three issues: (i)--the spatial occurrence of chromospheric 3--min oscillations; (ii)--the validity of Ca II H&K line-center Doppler Shift measurements; (iii)--the signi ?cance of oscillation power and phase at frequencies above 10 mHz.

Theoretical models for designing a 220-GHz folded waveguide backward wave oscillator

International Nuclear Information System (INIS)

Cai Jin-Chi; Chen Huai-Bi; Hu Lin-Lin; Ma Guo-Wu; Chen Hong-Bin; Jin Xiao

2015-01-01

In this paper, the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide (FW) backward wave oscillator (BWO) are described. On the whole, these equations are mainly classified into small signal model (SSM), large signal model (LSM), and simplified small signal model (SSSM). Using these linear and nonlinear one-dimensional (1D) models, the oscillation characteristics of the FW BWO of a given configuration of slow wave structure (SWS) can be calculated by numerical iteration algorithm, which is more time efficient than three-dimensional (3D) particle-in-cell (PIC) simulation. The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently. The dispersion characteristics of the FW are obtained by equivalent circuit analysis. The space charge effect, the end reflection effect, the lossy wall effect, and the relativistic effect are all considered in our models to offer more accurate results. The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated. The 3D PIC method is adopted to verify the theoretical design results, which shows that they are in good agreement with each other. (paper)

Influence of disorder and magnetic field on conductance of “sandwich” type two dimensional system

Directory of Open Access Journals (Sweden)

Long LIU

2017-04-01

Full Text Available In order to discuss the transport phenomena and the physical properties of the doping of the disorder system under magnetic field, the electron transport in a two-dimensional system is studied by using Green function and scattering matrix theory. Base on the two-dimensional lattice model, the phenomenon of quantized conductance of the "sandwich" type electronic system is analyzed. The contact between the lead and the scatterer reduce the system's conductance, and whittle down the quantum conductance stair-stepping phenomenon; when an external magnetic field acts on to the system, the conductance presents a periodicity oscillation with the magnetic field. The intensity of this oscillation is related to the energy of the electron;with the increase of the impurity concentration, the conductance decreases.In some special doping concentration, the conductance of the system can reach the ideal step value corresponding to some special electron energy. The result could provide reference for further study of the conductance of the "sandwich" type two dimensional system.

Nonstationary oscillation of gyrotron backward wave oscillators with cylindrical interaction structure

International Nuclear Information System (INIS)

Chen, Shih-Hung; Chen, Liu

2013-01-01

The nonstationary oscillation of the gyrotron backward wave oscillator (gyro-BWO) with cylindrical interaction structure was studied utilizing both steady-state analyses and time-dependent simulations. Comparisons of the numerical results reveal that the gyro-BWO becomes nonstationary when the trailing field structure completely forms due to the dephasing energetic electrons. The backward propagation of radiated waves with a lower resonant frequency from the trailing field structure interferes with the main internal feedback loop, thereby inducing the nonstationary oscillation of the gyro-BWO. The nonstationary gyro-BWO exhibits the same spectral pattern of modulated oscillations with a constant frequency separation between the central frequency and sidebands throughout the whole system. The frequency separation is found to be scaled with the square root of the maximum field amplitude, thus further demonstrating that the nonstationary oscillation of the gyro-BWO is associated with the beam-wave resonance detuning

Oscillation Baselining and Analysis Tool

Energy Technology Data Exchange (ETDEWEB)

2017-03-27

PNNL developed a new tool for oscillation analysis and baselining. This tool has been developed under a new DOE Grid Modernization Laboratory Consortium (GMLC) Project (GM0072 - “Suite of open-source applications and models for advanced synchrophasor analysis”) and it is based on the open platform for PMU analysis. The Oscillation Baselining and Analysis Tool (OBAT) performs the oscillation analysis and identifies modes of oscillations (frequency, damping, energy, and shape). The tool also does oscillation event baselining (fining correlation between oscillations characteristics and system operating conditions).

Varicose and cheerio collaborate with pebble to mediate semaphorin-1a reverse signaling in Drosophila.

Science.gov (United States)

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.

Mechanical analog of the synchrotron, illustrating phase stability and two-dimensional focusing

International Nuclear Information System (INIS)

Alvarez, L.W.; Smits, R.; Senecal, G.

1975-01-01

A steel ball bounces in synchronism with a vertically oscillating piston. The piston surface is a hardened steel disk on which the ball bounces; two-dimensional horizontal focusing is provided by the concavity of the surface. The period of oscillation can be varied over a 3:1 range with the amplitude kept constant. As the period is increased, the ball bounces higher. As the period is decreased, the ball bounces lower, contrary to the intuition of most observers. The model illustrates the important properties of synchrotron accelerators. (3 figures)

Magnetic anisotropy of two-dimensional nanostructures: Transition-metal triangular stripes

International Nuclear Information System (INIS)

Dorantes-Davila, J.; Villasenor-Gonzalez, P.; Pastor, G.M.

2005-01-01

The magnetic anisotropy energy (MAE) of one-dimensional stripes having infinite length and triangular lateral structure are investigated in the framework of a self-consistent tight-binding method. One observes discontinuous changes in the easy magnetization direction along the crossover from one to two dimensions. The MAE oscillates as a function of stripe width and depends strongly on the considered transition metal (TM). The MAE of the two-leg ladder is strongly reduced as compared to that of the monoatomic chain and the convergence to the two-dimensional limit is rather slow

Symmetries and invariants of the oscillator and envelope equations with time-dependent frequency

Directory of Open Access Journals (Sweden)

Hong Qin

2006-05-01

Full Text Available The single-particle dynamics in a time-dependent focusing field is examined. The existence of the Courant-Snyder invariant, a fundamental concept in accelerator physics, is fundamentally a result of the corresponding symmetry admitted by the harmonic oscillator equation with linear time-dependent frequency. It is demonstrated that the Lie algebra of the symmetry group for the oscillator equation with time-dependent frequency is eight dimensional, and is composed of four independent subalgebras. A detailed analysis of the admitted symmetries reveals a deeper connection between the nonlinear envelope equation and the oscillator equation. A general theorem regarding the symmetries and invariants of the envelope equation, which includes the existence of the Courant-Snyder invariant as a special case, is demonstrated. As an application to accelerator physics, the symmetries of the envelope equation enable a fast numerical algorithm for finding matched solutions without using the conventional iterative Newton’s method, where the envelope equation needs to be numerically integrated once for every iteration, and the Jacobi matrix needs to be calculated for the envelope perturbation.

Neutrino oscillations in matter

International Nuclear Information System (INIS)

Mikheyev, S.P.; Smirnov, A.Yu.

1986-01-01

In this paper we describe united formalism of ν-oscillations for different regimes, which is immediate generalization of vacuum oscillations theory. Adequate graphical representation of this formalism is given. We summarize main properties of ν-oscillations for different density distributions. (orig./BBOE)

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...

Analytic energies and wave functions of the two-dimensional Schrodinger equation: ground state of two-dimensional quartic potential and classification of solutions

Czech Academy of Sciences Publication Activity Database

Tichý, V.; Kuběna, Aleš Antonín; Skála, L.

2012-01-01

Roč. 90, č. 6 (2012), s. 503-513 ISSN 0008-4204 Institutional support: RVO:67985556 Keywords : Schroninger equation * partial differential equation * analytic solution * anharmonic oscilator * double-well Subject RIV: BE - Theoretical Physics Impact factor: 0.902, year: 2012 http://library.utia.cas.cz/separaty/2012/E/kubena-analytic energies and wave functions of the two-dimensional schrodinger equation.pdf

Quantum oscillations of thermomagnetic coefficients of layered conductors in a strong magnetic field

International Nuclear Information System (INIS)

Kirichenko, O.V.; Kozlov, I.V.; Peschansky, V.G.; Krstovska, D.

2008-01-01

The linear response of the electronic system of a conductor to a perturbation in the form of an electric field and a temperature gradient in a quantizing magnetic field B is investigated theoretically. The thermoelectric effect in a layered conductor is analyzed and it is shown that the quasi-two-dimensional character of the dispersion law of the charge carriers results in gigantic oscillations of the thermo-emf

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.

Lyapunov exponent of the random frequency oscillator: cumulant expansion approach

International Nuclear Information System (INIS)

Anteneodo, C; Vallejos, R O

2010-01-01

We consider a one-dimensional harmonic oscillator with a random frequency, focusing on both the standard and the generalized Lyapunov exponents, λ and λ* respectively. We discuss the numerical difficulties that arise in the numerical calculation of λ* in the case of strong intermittency. When the frequency corresponds to a Ornstein-Uhlenbeck process, we compute analytically λ* by using a cumulant expansion including up to the fourth order. Connections with the problem of finding an analytical estimate for the largest Lyapunov exponent of a many-body system with smooth interactions are discussed.

Oscillation matrices and kernels and small vibrations of mechanical systems

CERN Document Server

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

Hydrodynamic Characteristics and Strength Analysis of a Novel Dot-matrix Oscillating Wave Energy Converter

Science.gov (United States)

Shao, Meng; Xiao, Chengsi; Sun, Jinwei; Shao, Zhuxiao; Zheng, Qiuhong

2017-12-01

The paper analyzes hydrodynamic characteristics and the strength of a novel dot-matrix oscillating wave energy converter, which is in accordance with nowadays’ research tendency: high power, high efficiency, high reliability and low cost. Based on three-dimensional potential flow theory, the paper establishes motion control equations of the wave energy converter unit and calculates wave loads and motions. On this basis, a three-dimensional finite element model of the device is built to check its strength. Through the analysis, it can be confirmed that the WEC is feasible and the research results could be a reference for wave energy’s exploration and utilization.

A non-Abelian SO(8) monopole as generalization of Dirac-Yang monopoles for a 9-dimensional space

International Nuclear Information System (INIS)

Le, Van-Hoang; Nguyen, Thanh-Son

2011-01-01

We establish an explicit form of a non-Abelian SO(8) monopole in a 9-dimensional space and show that it is indeed a direct generalization of Dirac and Yang monopoles. Using the generalized Hurwitz transformation, we have found a connection between a 16-dimensional harmonic oscillator and a 9-dimensional hydrogenlike atom in the field of the SO(8) monopole (MICZ-Kepler problem). Using the built connection the group of dynamical symmetry of the 9-dimensional MICZ-Kepler problem is found as SO(10, 2).

Improved method for eliminating center-of-mass coordinates from matrix elements in oscillator basis

International Nuclear Information System (INIS)

Richardson, R.H.; Shapiro, J.Y.

1986-01-01

This paper presents a concise, efficient method of reducing potential energy matrix elements to relative coordinates, when one is using an oscillator basis. It is especially suited to computer calculations. One nice feature of the method is its modular form, which allows a wide range of calculations. Separate FORTRAN subroutines have been written which calculate and store tables of the one-dimensional brackets of an equation that is presented and the single particle brackets from the isotropic to the axially symmetric oscillator equations. The tables are used by other subroutines which calculate the modified brackets and the brackets with spin. The methods developed here are a substantial improvement over what has been done heretofore, and open up new possibilities for performing nuclear structure calculations

Persistent fluctuations in synchronization rate in globally coupled oscillators with periodic external forcing

Science.gov (United States)

Atsumi, Yu; Nakao, Hiroya

2012-05-01

A system of phase oscillators with repulsive global coupling and periodic external forcing undergoing asynchronous rotation is considered. The synchronization rate of the system can exhibit persistent fluctuations depending on parameters and initial phase distributions, and the amplitude of the fluctuations scales with the system size for uniformly random initial phase distributions. Using the Watanabe-Strogatz transformation that reduces the original system to low-dimensional macroscopic equations, we show that the fluctuations are collective dynamics of the system corresponding to low-dimensional trajectories of the reduced equations. It is argued that the amplitude of the fluctuations is determined by the inhomogeneity of the initial phase distribution, resulting in system-size scaling for the random case.

Magnetically Coupled Magnet-Spring Oscillators

Science.gov (United States)

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…

Oscillation of two-dimensional linear second-order differential systems

International Nuclear Information System (INIS)

Kwong, M.K.; Kaper, H.G.

1985-01-01

This article is concerned with the oscillatory behavior at infinity of the solution y: [a, ∞) → R 2 of a system of two second-order differential equations, y''(t) + Q(t) y(t) = 0, t epsilon[a, ∞); Q is a continuous matrix-valued function on [a, ∞) whose values are real symmetric matrices of order 2. It is shown that the solution is oscillatory at infinity if the largest eigenvalue of the matrix integral/sub a//sup t/ Q(s) ds tends to infinity as t → ∞. This proves a conjecture of D. Hinton and R.T. Lewis for the two-dimensional case. Furthermore, it is shown that considerably weaker forms of the condition still suffice for oscillatory behavior at infinity. 7 references

Collective excitations and superconductivity in reduced dimensional systems - Possible mechanism for high Tc

International Nuclear Information System (INIS)

Santoyo, B.M.

1989-01-01

The author studies in full detail a possible mechanism of superconductivity in slender electronic systems of finite cross section. This mechanism is based on the pairing interaction mediated by the multiple modes of acoustic plasmons in these structures. First, he shows that multiple non-Landau-damped acoustic plasmon modes exist for electrons in a quasi-one dimensional wire at finite temperatures. These plasmons are of two basic types. The first one is made up by the collective longitudinal oscillations of the electrons essentially of a given transverse energy level oscillating against the electrons in the neighboring transverse energy level. The modes are called Slender Acoustic Plasmons or SAP's. The other mode is the quasi-one dimensional acoustic plasmon mode in which all the electrons oscillate together in phase among themselves but out of phase against the positive ion background. He shows numerically and argues physically that even for a temperature comparable to the mode separation Δω the SAP's and the quasi-one dimensional plasmon persist. Then, based on a clear physical picture, he develops in terms of the dielectric function a theory of superconductivity capable of treating the simultaneous participation of multiple bosonic modes that mediate the pairing interaction. The effect of mode damping is then incorporated in a simple manner that is free of the encumbrance of the strong-coupling, Green's function formalism usually required for the retardation effect. Explicit formulae including such damping are derived for the critical temperature T c and the energy gap Δ 0 . With those modes and armed with such a formalism, he proceeds to investigate a possible superconducting mechanism for high T c in quasi-one dimensional single-wire and multi-wire systems

Optically detected SdH oscillations in CdTe/(CdMg)Te and CdTe/(CdMnMg)Te modulation doped quantum wells

Energy Technology Data Exchange (ETDEWEB)

Shen, J.X.; Ossau, W.; Fischer, F.; Waag, A.; Landwehr, G. [Physikalisches Institut der Uniwersitaet Wuerzburg, Wuerzburg (Germany)

1995-12-31

Oscillations of photoluminescence properties in external magnetic fields are investigated in CdTe modulation doped quantum wells. The oscillatory behaviour of the luminescence intensity, the line width and the g factor is due to many-body effects in the 2-dimensional electron gas. The oscillation of photoluminescence intensity can be easily used as optically detected Shubnikov de Haas effect to determine the electron concentration in quantum wells without contacts. (author). 5 refs, 3 figs, 1 tab.

Are there intracellular Ca2+ oscillations correlated with flagellar beating in human sperm? A three vs. two-dimensional analysis.

Science.gov (United States)

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

Vapor plume oscillation mechanisms in transient keyhole during tandem dual beam fiber laser welding

Science.gov (United States)

Chen, Xin; Zhang, Xiaosi; Pang, Shengyong; Hu, Renzhi; Xiao, Jianzhong

2018-01-01

Vapor plume oscillations are common physical phenomena that have an important influence on the welding process in dual beam laser welding. However, until now, the oscillation mechanisms of vapor plumes remain unclear. This is primarily because mesoscale vapor plume dynamics inside a millimeter-scale, invisible, and time-dependent keyhole are difficult to quantitatively observe. In this paper, based on a developed three-dimensional (3D) comprehensive model, the vapor plume evolutions in a dynamical keyhole are directly simulated in tandem dual beam, short-wavelength laser welding. Combined with the vapor plume behaviors outside the keyhole observed by high-speed imaging, the vapor plume oscillations in dynamical keyholes at different inter-beam distances are the first, to our knowledge, to be quantitatively analyzed. It is found that vapor plume oscillations outside the keyhole mainly result from vapor plume instabilities inside the keyhole. The ejection velocity at the keyhole opening and dynamical behaviors outside the keyhole of a vapor plume both violently oscillate with the same order of magnitude of high frequency (several kHz). Furthermore, the ejection speed at the keyhole opening and ejection area outside the keyhole both decrease as the beam distance increases, while the degree of vapor plume instability first decreases and then increases with increasing beam distance from 0.6 to 1.0 mm. Moreover, the oscillation mechanisms of a vapor plume inside the dynamical keyhole irradiated by dual laser beams are investigated by thoroughly analyzing the vapor plume occurrence and flow process. The vapor plume oscillations in the dynamical keyhole are found to mainly result from violent local evaporations and severe keyhole geometry variations. In short, the quantitative method and these findings can serve as a reference for further understanding of the physical mechanisms in dual beam laser welding and of processing optimizations in industrial applications.

Electromagnetically actuated micromanipulator using an acoustically oscillating bubble

International Nuclear Information System (INIS)

Kwon, J O; Yang, J S; Lee, S J; Rhee, K; Chung, S K

2011-01-01

A novel non-invasive micromanipulation technique has been developed where a microrobot swimming in an aqueous medium manipulates micro-objects, through electromagnetic actuation using an acoustically oscillating bubble attached to the microrobot as a grasping tool. This micromanipulation concept was experimentally verified; an investigation of electromagnetic actuation and acoustic excitation was also performed. Two-dimensional propulsion of a magnetic piece was demonstrated through electromagnetic actuation, using three pairs of electric coils surrounding the water chamber, and confirming that the propulsion speed of the magnetic piece was linearly proportional to the applied current intensity. Micro-object manipulation was separately demonstrated using an air bubble with glass beads (80 µm diameter) and a steel ball (800 µm diameter) in an aqueous medium. Upon acoustic excitation of the bubble by a piezo-actuator around its resonant frequency, the generated radiation force attracted and captured the neighboring glass beads and steel ball. The grasping force was indirectly measured by exposing the glass beads captured by the oscillating bubble to a stream generated by an auto-syringe pump in a mini-channel. By measuring the maximum speed of the streaming flow when the glass beads detached from the oscillating bubble and flowed downstream, the grasping force was calculated as 50 nN, based on Stokes' drag approximation. Finally, a fish egg was successfully manipulated with the integration of electromagnetic actuation and acoustic excitation, using a mini-robot consisting of a millimeter-sized magnetic piece with a bubble attached to its bottom. This novel micromanipulation may be an efficient tool for both micro device assembly and single-cell manipulation.

Electromagnetically actuated micromanipulator using an acoustically oscillating bubble

Science.gov (United States)

Kwon, J. O.; Yang, J. S.; Lee, S. J.; Rhee, K.; Chung, S. K.

2011-11-01

A novel non-invasive micromanipulation technique has been developed where a microrobot swimming in an aqueous medium manipulates micro-objects, through electromagnetic actuation using an acoustically oscillating bubble attached to the microrobot as a grasping tool. This micromanipulation concept was experimentally verified; an investigation of electromagnetic actuation and acoustic excitation was also performed. Two-dimensional propulsion of a magnetic piece was demonstrated through electromagnetic actuation, using three pairs of electric coils surrounding the water chamber, and confirming that the propulsion speed of the magnetic piece was linearly proportional to the applied current intensity. Micro-object manipulation was separately demonstrated using an air bubble with glass beads (80 µm diameter) and a steel ball (800 µm diameter) in an aqueous medium. Upon acoustic excitation of the bubble by a piezo-actuator around its resonant frequency, the generated radiation force attracted and captured the neighboring glass beads and steel ball. The grasping force was indirectly measured by exposing the glass beads captured by the oscillating bubble to a stream generated by an auto-syringe pump in a mini-channel. By measuring the maximum speed of the streaming flow when the glass beads detached from the oscillating bubble and flowed downstream, the grasping force was calculated as 50 nN, based on Stokes' drag approximation. Finally, a fish egg was successfully manipulated with the integration of electromagnetic actuation and acoustic excitation, using a mini-robot consisting of a millimeter-sized magnetic piece with a bubble attached to its bottom. This novel micromanipulation may be an efficient tool for both micro device assembly and single-cell manipulation.

Emission of SNF-oscillations by the plasma - periodic decelerating structure system

International Nuclear Information System (INIS)

Antonov, A.N.; Gestrina, G.N.; Kovpik, O.F.; Kornilov, E.A.; Moiseev, S.S.

1983-01-01

Emission of SHF-oscillations by a magnetoactive plasma inside a decelerating structure (annular waveguide), which is excited by an electron beam, has been studied. The electron beam is formed by a diode electron gun. Pulse duration was 400 μs, beam energy = 10 keV, current - up to 5 A. The beam 1.8 cm in diameter is injected into a glass interaction chamber. The chamber diameter is 20 cm, the length is 1 m. The interaction chamber and electron gun chamber were placed in a homogeneous magnetic field with intensity up to 2.5x10 5 axm -1 . The periodic deceleration structure was located in the interaction chamber coaxially with the electron beam. The structure total length was 40 cm. The working gas, argon, was fed into the structure through a needle injector. It is shown that the three-dimensional waves appearing in the plasma can be transformed by the structure to those emited without plasma density gradients and magnetic field. Conditions of effective separation of the energy of SHF-oscillations from the system: plasm-beam-narrow-slit decelerating structure are found. The above system can be used for amplification and generation of monochromatic oscillations in the millimeter waves range. Results of experimental studies are compared with theoretical calculations

Numerical study on optimal Stirling engine regenerator matrix designs taking into account the effects of matrix temperature oscillations

International Nuclear Information System (INIS)

Andersen, Stig Kildegard; Carlsen, Henrik; Thomsen, Per Grove

2006-01-01

A new regenerator matrix design that improves the efficiency of a Stirling engine has been developed in a numerical study of the existing SM5 Stirling engine. A new, detailed, one-dimensional Stirling engine model that delivers results in good agreement with experimental data was used for mapping the performance of the engine, for mapping the effects of regenerator matrix temperature oscillations, and for optimising the regenerator design. The regenerator matrix temperatures were found to oscillate in two modes. The first mode was oscillation of a nearly linear axial matrix temperature profile while the second mode bended the ends of the axial matrix temperature profile when gas flowed into the regenerator with a temperature significantly different from the matrix temperature. The first mode of oscillation improved the efficiency of the engine but the second mode reduced both the work output and efficiency of the engine. A new regenerator with three differently designed matrix sections that amplified the first mode of oscillation and reduced the second improved the efficiency of the engine from the current 32.9 to 33.2% with a 3% decrease in power output. An efficiency of 33.0% was achievable with uniform regenerator matrix properties

Excitonic effects and related properties in semiconductor nanostructures: roles of size and dimensionality

Science.gov (United States)

Wu, Shudong; Cheng, Liwen; Wang, Qiang

2017-08-01

The size- and dimensionality-dependence of excitonic effects and related properties in semiconductor nanostructures are theoretically studied in detail within the effective-mass approximation. When nanostructure sizes become smaller than the bulk exciton Bohr radius, excitonic effects are significantly enhanced with reducing size or dimensionality. This is as a result of quantum confinement in more directions leading to larger exciton binding energies and normalized exciton oscillator strengths. These excitonic effects originate from electron-hole Coulombic interactions, which strongly enhance the oscillator strength between the electron and hole. It is also established that the universal scaling of exciton binding energy versus the inverse of the exciton Bohr radius follows a linear scaling law. Herein, we propose a stretched exponential law for the size scaling of optical gap, which is in good agreement with the calculated data. Due to differences in the confinement dimensionality, the radiative lifetime of low-dimensional excitons becomes shorter than that of bulk excitons. The size dependence of the exciton radiative lifetimes is in good agreement with available experimental data. This strongly enhanced electron-hole exchange interaction is expected in low-dimensional structures due to enriched excitonic effects. The main difference in nanostructures compared to the bulk can be interpreted in terms of the enhanced excitonic effects induced by exciton localization. The enhanced excitonic effects are expected to be of importance in developing stable and high-efficiency nanoscale excitonic optoelectronic devices.

Memristor-based reactance-less oscillator

KAUST Repository

Zidan, Mohammed A.; Omran, Hesham; Radwan, Ahmed G.; Salama, Khaled N.

2012-01-01

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.

Memristor-based reactance-less oscillator

KAUST Repository

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.

A theory of generalized Bloch oscillations

International Nuclear Information System (INIS)

Duggen, Lars; Lassen, Benny; Lew Yan Voon, L C; Willatzen, Morten

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 calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics. (paper)

Reactor oscillator - I - III, Part I

International Nuclear Information System (INIS)

Lolic, B.

1961-12-01

Project 'Reactor oscillator' covers the following activities: designing reactor oscillators for reactors RA and RB with detailed engineering drawings; constructing and mounting of the oscillator; designing and constructing the appropriate electronic equipment for the oscillator; measurements at the RA and RB reactors needed for completing the oscillator construction

Experimental determination of the electron effective masses and mobilities in each dimensionally-quantized subband in an InxGa1−xAs quantum well with InAs inserts

International Nuclear Information System (INIS)

Kulbachinskii, V. A.; Oveshnikov, L. N.; Lunin, R. A.; Yuzeeva, N. A.; Galiev, G. B.; Klimov, E. A.; Maltsev, P. P.

2015-01-01

HEMT structures with In 0.53 Ga 0.47 As quantum well are synthesized using molecular-beam epitaxy on InP substrates. The structures are double-side Si δ-doped so that two dimensionally-quantized subbands are occupied. The effect of the central InAs nanoinsert in the quantum well on the electron effective masses m* and mobilities in each subband is studied. For experimental determination of m*, the quantum μ q and transport μ t mobilities of the two-dimensional electron gas in each dimensionally-quantized subband, the Shubnikov-de Haas effect is measured at two temperatures of 4.2 and 8.4 K. The electron effective masses are determined by the temperature dependence of the oscillation amplitudes, separating the oscillations of each dimensionally-quantized subband. The Fourier spectra of oscillations are used to determine the electron mobilities μ q and μ t in each dimensionally-quantized subband. It is shown that m* decreases as the InAs-nanoinsert thickness d in the In 0.53 Ga 0.47 As quantum well and electron mobilities increase. The maximum electron mobility is observed at the insert thickness d = 3.4 nm

Neutrino Oscillation Physics

International Nuclear Information System (INIS)

Kayser, Boris

2014-01-01

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

Oscillator, neutron modulator

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

Neutrino Oscillation Physics

Energy Technology Data Exchange (ETDEWEB)

Kayser, Boris [Fermilab (United States)

2014-07-01

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.

Modeling A.C. Electronic Transport through a Two-Dimensional Quantum Point Contact

International Nuclear Information System (INIS)

Aronov, I.E.; Beletskii, N.N.; Berman, G.P.; Campbell, D.K.; Doolen, G.D.; Dudiy, S.V.

1998-01-01

We present the results on the a.c. transport of electrons moving through a two-dimensional (2D) semiconductor quantum point contact (QPC). We concentrate our attention on the characteristic properties of the high frequency admittance (ωapproximately0 - 50 GHz), and on the oscillations of the admittance in the vicinity of the separatrix (when a channel opens or closes), in presence of the relaxation effects. The experimental verification of such oscillations in the admittance would be a strong confirmation of the semi-classical approach to the a.c. transport in a QPC, in the separatrix region

OSCILLATING FILAMENTS. I. OSCILLATION AND GEOMETRICAL FRAGMENTATION

Energy Technology Data Exchange (ETDEWEB)

Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas, E-mail: gritschm@usm.uni-muenchen.de [University Observatory Munich, LMU Munich, Scheinerstrasse 1, D-81679 Munich (Germany)

2017-01-10

We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.

A one-dimensional heat transfer model for parallel-plate thermoacoustic heat exchangers

NARCIS (Netherlands)

de Jong, Anne; Wijnant, Ysbrand H.; de Boer, Andries

2014-01-01

A one-dimensional (1D) laminar oscillating flow heat transfer model is derived and applied to parallel-plate thermoacoustic heat exchangers. The model can be used to estimate the heat transfer from the solid wall to the acoustic medium, which is required for the heat input/output of thermoacoustic

Application of alternating current for dimensionally electrochemical machining

International Nuclear Information System (INIS)

Kacheev, M.K.; Kovalev, L.M.

1978-01-01

The results of comparative experimental investigations in dimensionally electrochemical machining of 1Kh18N9T steel using alternating and direct currents are presented. The effect of the electrolyte rate in the inter-electrode clearance, electrode voltage and oscillation amplitude of the electrode-tool on the metal output from the electrodes and the relief of the machined surface is studied. It is shown that the a.c. electrochemical machining permits to achieve the greater dimensional accuracy than the d.c. machining when choosing the proper voltage and electrolyte composition. It is connected with the fact that the prevailing part of the metal output is obtained in the impulse-asymmetrical regime when the inter-electrode clearance is minimum

Coexisting synchronous and asynchronous states in locally coupled array of oscillators by partial self-feedback control

Science.gov (United States)

Bera, Bidesh K.; Ghosh, Dibakar; Parmananda, Punit; Osipov, G. V.; Dana, Syamal K.

2017-07-01

We report the emergence of coexisting synchronous and asynchronous subpopulations of oscillators in one dimensional arrays of identical oscillators by applying a self-feedback control. When a self-feedback is applied to a subpopulation of the array, similar to chimera states, it splits into two/more sub-subpopulations coexisting in coherent and incoherent states for a range of self-feedback strength. By tuning the coupling between the nearest neighbors and the amount of self-feedback in the perturbed subpopulation, the size of the coherent and the incoherent sub-subpopulations in the array can be controlled, although the exact size of them is unpredictable. We present numerical evidence using the Landau-Stuart system and the Kuramoto-Sakaguchi phase model.

Transport and flow characteristics of an oscillating cylindrical fiber for total artificial lung application

KAUST Repository

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

Transport and flow characteristics of an oscillating cylindrical fiber for total artificial lung application

KAUST Repository

Qamar, Adnan; Bull, Joseph L.

2017-01-01

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

Free oscillation of the Earth

Directory of Open Access Journals (Sweden)

Y. Abedini

2000-06-01

Full Text Available   This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillations of stars was studied by Cowling and others. They classified the oscillation modes of the stars into acoustic and gravity modes on the basis of their driving forces. These are pressure and buoyancy forces respectively. The earliest measurements for the period of the free oscillations of the Earth was made by Benyove from a study of Kamchathca earthquake. Since then, the Geophysicists have been trying to provide a theoretical basis for these measurements. Recently, the theory concerning oscillations of celestial fluids is extended by Sobouti to include the possible oscillations of the Earthlike bodies. Using the same technique, we study the free oscillations of a spherically symmetric, non-rotating and elastic model for the Earth.   We used the actual data of the Earths interior structure in our numerical calculations. Numerical results show that there exist three distinct oscillation modes namely acoustic, gravity and toroidal modes. These modes are driven by pressure, buoyancy and shear forces respectively. The shear force is due to the elastic properties of the solid part of the Earth. Our numerical results are consistent with the seismic data recorded from earthquake measurements.

Investigation of steady plasma actuation effect on aerodynamic coefficients of oscillating airfoil at low Reynolds number

Directory of Open Access Journals (Sweden)

Arash Mahboubidoust

2017-07-01

Full Text Available In this work, numerical study of two dimensional laminar incompressible flow around an oscillating NACA0012 airfoil is proceeded using the open source code OpenFOAM. Oscillatory motion types including pitching and flapping are considered. Reynolds number for these motions is assumed to be 12000 and effects of these motions and also different unsteady parameters such as amplitude and reduced frequency on aerodynamic coefficients are studied. For flow control on airfoil, dielectric barrier discharge plasma actuator is used in two different positions on airfoil and its effect is compared for the two types of considered oscillating motions. It is observed that in pitching motion, imposing plasma leads to an improvement in aerodynamic coefficients, but it does not have any positive effect on flapping motion. Also, for the amplitudes and frequencies investigated in this paper, the trailing edge plasma had a more desirable effect than other positions. Keywords: Airfoil, Flapping, Oscillating, Plasma, Pitching

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

Nanopore Current Oscillations: Nonlinear Dynamics on the Nanoscale.

Science.gov (United States)

Hyland, Brittany; Siwy, Zuzanna S; Martens, Craig C

2015-05-21

In this Letter, we describe theoretical modeling of an experimentally realized nanoscale system that exhibits the general universal behavior of a nonlinear dynamical system. In particular, we consider the description of voltage-induced current fluctuations through a single nanopore from the perspective of nonlinear dynamics. We briefly review the experimental system and its behavior observed and then present a simple phenomenological nonlinear model that reproduces the qualitative behavior of the experimental data. The model consists of a two-dimensional deterministic nonlinear bistable oscillator experiencing both dissipation and random noise. The multidimensionality of the model and the interplay between deterministic and stochastic forces are both required to obtain a qualitatively accurate description of the physical system.

Self-Synchronized Phenomena Generated in Rotor-Type Oscillators: On the Influence of Coupling Condition between Oscillators

Science.gov (United States)

Bonkobara, Yasuhiro; Mori, Hiroki; Kondou, Takahiro; Ayabe, Takashi

Self-synchronized phenomena generated in rotor-type oscillators mounted on a straight-line spring-mass system are investigated experimentally and analytically. In the present study, we examine the occurrence region and pattern of self-synchronization in two types of coupled oscillators: rigidly coupled oscillators and elastically coupled oscillators. It is clarified that the existence regions of stable solutions are governed mainly by the linear natural frequency of each spring-mass system. The results of numerical analysis confirm that the self-synchronized solutions of the elastically coupled oscillators correspond to those of the rigidly coupled oscillators. In addition, the results obtained in the present study are compared with the previously reported results for a metronome system and a moving apparatus and the different properties of the phenomena generated in the rotor-type oscillators and the pendulum-type oscillators are shown in terms of the construction of branches of self-synchronized solution and the stability.

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 equati...

Supersymmetric quantum mechanics in three-dimensional space, 1

International Nuclear Information System (INIS)

Ui, Haruo

1984-01-01

As a direct generalization of the model of supersymmetric quantum mechanics by Witten, which describes the motion of a spin one-half particle in the one-dimensional space, we construct a model of the supersymmetric quantum mechanics in the three-dimensional space, which describes the motion of a spin one-half particle in central and spin-orbit potentials in the context of the nonrelativistic quantum mechanics. With the simplest choice of the (super) potential, this model is shown to reduce to the model of the harmonic oscillator plus constant spin-orbit potential of unit strength of both positive and negative signs, which was studied in detail in our recent paper in connection with ''accidental degeneracy'' as well as the ''graded groups''. This simplest model is discussed in some detail as an example of the three-dimensional supersymmetric quantum mechanical system, where the supersymmetry is an exact symmetry of the system. More general choice of a polynomial superpotential is also discussed. It is shown that the supersymmetry cannot be spontaneously broken for any polynomial superpotential in our three-dimensional model; this result is contrasted to the corresponding one in the one-dimensional model. (author)

Three dimensional δf simulations of beams in the SSC

International Nuclear Information System (INIS)

Koga, J.; Tajima, T.; Machida, S.

1993-01-01

A three dimensional δf strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3 dimensional space charge effects and a δf code. The δf method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6 dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3 dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense with finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed

Three dimensional [delta]f simulations of beams in the SSC

Energy Technology Data Exchange (ETDEWEB)

Koga, J.; Tajima, T. (Texas Univ., Austin, TX (United States). Inst. for Fusion Studies); Machida, S. (Superconducting Super Collider Lab., Dallas, TX (United States))

1993-02-01

A three dimensional [delta]f strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3-dimensional space charge effects and a [delta]f code. The [delta]f method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6-dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3-dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense where finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed.

Three dimensional {delta}f simulations of beams in the SSC

Energy Technology Data Exchange (ETDEWEB)

Koga, J.; Tajima, T. [Texas Univ., Austin, TX (United States). Inst. for Fusion Studies; Machida, S. [Superconducting Super Collider Lab., Dallas, TX (United States)

1993-02-01

A three dimensional {delta}f strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3-dimensional space charge effects and a {delta}f code. The {delta}f method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6-dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3-dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense where finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed.

Three dimensional δf simulations of beams in the SSC

International Nuclear Information System (INIS)

Koga, J.; Tajima, T.

1993-02-01

A three dimensional δf strong-strong algorithm has been developed to apply to the study of such effects as space charge and beam-beam interaction phenomena in the Superconducting Super Collider (SSC). The algorithm is obtained from the merging of the particle tracking code Simpsons used for 3-dimensional space charge effects and a δf code. The δf method is used to follow the evolution of the non-gaussian part of the beam distribution. The advantages of this method are twofold. First, the Simpsons code utilizes a realistic accelerator model including synchrotron oscillations and energy ramping in 6-dimensional phase space with electromagnetic fields of the beams calculated using a realistic 3-dimensional field solver. Second, the beams are evolving in the fully self-consistent strong-strong sense where finite particle fluctuation noise is greatly reduced as opposed to the weak-strong models where one beam is fixed

Zero-point oscillations, zero-point fluctuations, and fluctuations of zero-point oscillations

International Nuclear Information System (INIS)

Khalili, Farit Ya

2003-01-01

Several physical effects and methodological issues relating to the ground state of an oscillator are considered. Even in the simplest case of an ideal lossless harmonic oscillator, its ground state exhibits properties that are unusual from the classical point of view. In particular, the mean value of the product of two non-negative observables, kinetic and potential energies, is negative in the ground state. It is shown that semiclassical and rigorous quantum approaches yield substantially different results for the ground state energy fluctuations of an oscillator with finite losses. The dependence of zero-point fluctuations on the boundary conditions is considered. Using this dependence, it is possible to transmit information without emitting electromagnetic quanta. Fluctuations of electromagnetic pressure of zero-point oscillations are analyzed, and the corresponding mechanical friction is considered. This friction can be viewed as the most fundamental mechanism limiting the quality factor of mechanical oscillators. Observation of these effects exceeds the possibilities of contemporary experimental physics but almost undoubtedly will be possible in the near future. (methodological notes)

Brain Oscillations, Hypnosis, and Hypnotizability.

Science.gov (United States)

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.

Prevalência do refluxo na veia safena parva em varizes primárias não complicadas dos membros inferiores pelo eco-Doppler colorido Prevalence of short saphenous vein reflux in primary uncomplicated varicose veins by Doppler ultrasonography

Directory of Open Access Journals (Sweden)

Fabio Secchi

2006-03-01

Full Text Available OBJETIVO: Determinar a prevalência de refluxo venoso na veia safena parva em membros inferiores com varizes primárias não complicadas pelo eco-Doppler colorido. MÉTODO: No período de 18 meses, 1.953 pacientes foram submetidos ao eco-Doppler colorido de membros inferiores por doença venosa. Destes, 1.631 com varizes primárias não complicadas foram selecionados para esta análise, sendo que 1.383 eram do sexo feminino (84,79% e 248 (15,21% do sexo masculino. A média de idade dos pacientes foi de 42,89 (± 0,48 anos, variando de 13 a 85 anos. Dos 1.631 pacientes, 1.323 foram submetidos a exame bilateral e 308 a exame unilateral, totalizando 2.954 membros inferiores com varizes primárias não complicadas avaliados. Desse total, 1.461 eram membros inferiores direitos e 1.493, esquerdos. Todos os exames foram realizados seguindo o mesmo protocolo. RESULTADO: Dos 2.954 membros inferiores avaliados, 372 (12,59% apresentaram refluxo em veia safena parva. A prevalência nos homens foi de 14,08% e, nas mulheres, de 12,35%. O refluxo da safena parva foi maior no membro inferior esquerdo (13.13% do que no direito (12,05%. A prevalência do refluxo foi significativamente maior nos pacientes acima de 60 anos. CONCLUSÃO: O refluxo da veia safena parva é relativamente comum, e sua pesquisa deve ser sempre realizada em pacientes com varizes primárias de membros inferiores.OBJECTIVE: To determine the prevalence of small saphenous vein reflux (SSVR in patients with uncomplicated varicose veins, using color-flow Doppler ultrasonography. METHOD: Over an 18-month period, a total of 1,953 patients underwent color-flow Doppler ultrasonography for evaluation of venous disease. Out of the total, 1,631 patients with primary uncomplicated varicose veins were selected for this study: 1,383 (84.79% patients were female and 248 (15.21% were male. Mean age was 42.9 (± 0.48 years, ranging from 13 to 85 years. Of the 1,631 patients, 1,323 underwent bilateral

Single ICCII Sinusoidal Oscillators Employing Grounded Capacitors

Directory of Open Access Journals (Sweden)

J. W. Horng

2011-09-01

Full Text Available Two inverting second-generation current conveyors (ICCII based sinusoidal oscillators are presented. The first sinusoidal oscillator is composed of one ICCII, two grounded capacitors and two resistors. The oscillation condition and oscillation frequency can be orthogonally controllable. The second sinusoidal oscillator is composed of one ICCII, two grounded capacitors and three resistors. The oscillation condition and oscillation frequency can be independently controllable through different resistors.

The study on pressure oscillation and heat transfer characteristics of oscillating capillary tube heat pipe

International Nuclear Information System (INIS)

Kim, Jong Soo; Bui, Ngoc Hung; Jung, Hyun Seok; Lee, Wook Hyun

2003-01-01

In the present study, the characteristics of pressure oscillation and heat transfer performance in an oscillating capillary tube heat pipe were experimentally investigated with respect to the heat flux, the charging ratio of working fluid, and the inclination angle to the horizontal orientation. The experimental results showed that the frequency of pressure oscillation was between 0.1 Hz and 1.5 Hz at the charging ratio of 40 vol.%. The saturation pressure of working fluid in the oscillating capillary tube heat pipe increased as the heat flux was increased. Also, as the charging ratio of working fluid was increased, the amplitude of pressure oscillation increased. When the pressure waves were symmetric sinusoidal waves at the charging ratios of 40 vol.% and 60 vol.%, the heat transfer performance was improved. At the charging ratios of 20 vol.% and 80 vol.%, the waveforms of pressure oscillation were more complicated, and the heat transfer performance reduced. At the charging ratio of 40 vol.%, the heat transfer performance of the OCHP was at the best when the inclination angle was 90 .deg., the pressure wave was a sinusoidal waveform, the pressure difference was at the least, the oscillation amplitude was at the least, and the frequency of pressure oscillation was the highest

Bimodal oscillations in nephron autoregulation

DEFF Research Database (Denmark)

Sosnovtseva, Olga; Pavlov, A.N.; Mosekilde, Erik

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 ...

The Bohr-Sommerfeld quantization of n-dimensional neutral and charged pulsons

International Nuclear Information System (INIS)

Bogolubsky, I.L.

1978-01-01

The spectrum of masses of 1) neutral and 2) having elementary charge Q=1 of n-dimensional pulsons (i.e., localized oscillating extended solutions) is found by numerical integration using a computer in the framework of the Klein-Gordon equation with the logarithmic nonlinearity. Computer experiments point out that the pulsons under consideration are apparently stable at any n

Case for neutrino oscillations

International Nuclear Information System (INIS)

Ramond, P.

1982-01-01

The building of a machine capable of producing an intense, well-calibrated beam of muon neutrinos is regarded by particle physicists with keen interest because of its ability of studying neutrino oscillations. The possibility of neutrino oscillations has long been recognized, but it was not made necessary on theoretical or experimental grounds; one knew that oscillations could be avoided if neutrinos were massless, and this was easily done by the conservation of lepton number. The idea of grand unification has led physicists to question the existence (at higher energies) of global conservation laws. The prime examples are baryon-number conservation, which prevents proton decay, and lepton-number conservation, which keeps neutrinos massless, and therefore free of oscillations. The detection of proton decay and neutrino oscillations would therefore be an indirect indication of the idea of Grand Unification, and therefore of paramount importance. Neutrino oscillations occur when neutrinos acquire mass in such a way that the neutrino mass eigenstates do not match the (neutrino) eigenstates produced by the weak interactions. We shall study the ways in which neutrinos can get mass, first at the level of the standard SU 2 x U 1 model, then at the level of its Grand Unification Generalizations

A Method to Determine Oscillation Emergence Bifurcation in Time-Delayed LTI System with Single Lag

Directory of Open Access Journals (Sweden)

Yu Xiaodan

2014-01-01

Full Text Available One type of bifurcation named oscillation emergence bifurcation (OEB found in time-delayed linear time invariant (abbr. LTI systems is fully studied. The definition of OEB is initially put forward according to the eigenvalue variation. It is revealed that a real eigenvalue splits into a pair of conjugated complex eigenvalues when an OEB occurs, which means the number of the system eigenvalues will increase by one and a new oscillation mode will emerge. Next, a method to determine OEB bifurcation in the time-delayed LTI system with single lag is developed based on Lambert W function. A one-dimensional (1-dim time-delayed system is firstly employed to explain the mechanism of OEB bifurcation. Then, methods to determine the OEB bifurcation in 1-dim, 2-dim, and high-dimension time-delayed LTI systems are derived. Finally, simulation results validate the correctness and effectiveness of the presented method. Since OEB bifurcation occurs with a new oscillation mode emerging, work of this paper is useful to explore the complex phenomena and the stability of time-delayed dynamic systems.

Quantum interference of ballistic carriers in one-dimensional semiconductor rings

International Nuclear Information System (INIS)

Bagraev, N.T.; Buravlev, A.D.; Klyachkin, L.E.; Malyarenko, A.M.; Ivanov, V.K.; Rykov, S.A.; Shelykh, I.A.

2000-01-01

Quantum interference of ballistic carriers has been studied for the first time, using one-dimensional rings formed by quantum wire pairs in self-assembled silicon quantum wells. Energy dependencies of the transmission coefficient is calculated as a function of the length and modulation of the quantum wire pairs separated by a unified drain-source system or the quantum point contacts. The quantum conductance is predicted to be increased by a factor of four using the unified drain-source system as a result of the quantum interference. Theoretical dependencies are revealed by the quantum conductance oscillations created by the deviations of both the drain-source voltage and external magnetic field inside the silicon one-dimensional rings. The results obtained put forward a basis to create the Aharonov-Bohm interferometer using the silicon one-dimensional ring [ru

Quantum magnetism in strongly interacting one-dimensional spinor Bose systems

DEFF Research Database (Denmark)

Salami Dehkharghani, Amin; Volosniev, A. G.; Lindgren, E. J.

2015-01-01

-range inter-species interactions much larger than their intra-species interactions and show that they have novel energetic and magnetic properties. In the strongly interacting regime, these systems have energies that are fractions of the basic harmonic oscillator trap quantum and have spatially separated......Strongly interacting one-dimensional quantum systems often behave in a manner that is distinctly different from their higher-dimensional counterparts. When a particle attempts to move in a one-dimensional environment it will unavoidably have to interact and 'push' other particles in order...... ground states with manifestly ferromagnetic wave functions. Furthermore, we predict excited states that have perfect antiferromagnetic ordering. This holds for both balanced and imbalanced systems, and we show that it is a generic feature as one crosses from few- to many-body systems....

Casimir energy density for spherical universes in n-dimensional spacetime

International Nuclear Information System (INIS)

Oezcan, Mustafa

2006-01-01

We consider the Casimir effect for the massless conformal scalar field in an n-dimensional, closed, static universe. We calculate the renormalized vacuum energy density using the covariant point-splitting method, the mode-sum regularization and the renormalized vacuum energy with the zeta-function regularization. We observe that all odd spacetime dimensions give us the zero renormalized vacuum energy density. For even spacetime dimensions the renormalized vacuum energy density oscillates in sign. The result agrees with three regularization techniques. The Casimir energy density for spherical universes in n-dimensional spacetime is regarded as interesting both to understand the correspondence between the sign of the effect and the dimension of manifold in topology and as a key to confirming the Casimir energy for half spherical universes (manifold with boundary) in n-dimensional spacetime

Anharmonic oscillator and Bogoliubov transformation

International Nuclear Information System (INIS)

Pattnayak, G.C.; Torasia, S.; Rath, B.

1990-01-01

The anharmonic oscillator occupies a cornerstone in many problems in physics. It was observed that none of the authors have tested Bogoliubov transformation to study anharmonic oscillator. The groundstate energy of the anharmonic oscillator is studied using Bogoliubov transformation and the results presented. (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

Heat transfer in a laminar separation bubble affected by oscillating external flow

International Nuclear Information System (INIS)

Wissink, J.G.; Michelassi, V.; Rodi, W.

2004-01-01

A three-dimensional Direct Numerical Simulation (DNS) of passive heat transfer in a Laminar Separation Bubble (LSB) over a flat plate affected by oscillating external flow is presented. The oscillation imposes a periodicity which is employed for phase-averaging. The flat plate is kept at a uniform, low temperature. The local Nusselt number, Nu, is determined as a function of phase. In the dead-air region of the bubble Nu is found to be relatively small, while it peaks in the recirculation region where hot outer fluid gets entrained and is transported towards the flat plate. Each period a new separation bubble is formed, that merges with the old separation bubble. The reverse flow inside the separation bubble reaches values of up to 60% of the local free-stream velocity, which is sufficient to make the separation bubble absolutely unstable such that self-sustained turbulence can exist. For the phase-averaged flow, neither the turbulent viscosity hypothesis nor the temperature gradient-diffusion hypothesis is found to hold

Modeling nonlinearities in MEMS oscillators.

Science.gov (United States)

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.

Analytical investigation of one-dimensional Rydberg atoms interacting with half-cycle pulses

International Nuclear Information System (INIS)

Bersons, I.; Veilande, R.

2004-01-01

Classical, quantum-mechanical, and semiclassical expressions for the transition probability in one-dimensional Rydberg atom irradiated by short half-cycle pulse are derived and compared. The simple formulas obtained for excitation of Rydberg atom by two time delayed weak half-cycle pulses reproduce well the experimental data and the solutions of time-dependent Schroedinger equation. When the transferred momenta are stronger and positive, the transition probabilities exhibit fast oscillations with time delay between the pulses. The classical transition probability is constant in time. For negative transferred momenta a focusing phenomenon is observed, and there is a region in time delay, where the transition probabilities oscillate with the Kepler period

Backscattering from width variations in quasi-one-dimensional strips of topological insulators

International Nuclear Information System (INIS)

Takagaki, Y

2012-01-01

Conductance modulations in wide-narrow-wide electron waveguides constructed from a two-dimensional topological insulator are investigated numerically. The conductance exhibits the Fabry-Perot oscillation at the opening of the helical edge states in the narrow segment when the potential offset imposed in the segment is varied. The quantum multiple reflections between the two ends of the narrow segment manifested by the oscillation demonstrate that the topological states are not protected from the scattering caused by an abrupt change in the channel width. The bulk states do not affect the vulnerability against the geometry scattering but they give rise to resonant transmission in an unconventional fashion.

Transport properties and giant Shubnikov-de Haas oscillations in the first organic conductor with metal complex anion containing selenocyanate ligand, (ET)2TlHg(SeCN)4

International Nuclear Information System (INIS)

Laukhin, V.N.; Audouard, A.; Rakoto, H.; Broto, J.M.; Goze, F.; Coffe, G.; Brossard, L.; Redoules, J.P.; Kartsovnik, M.V.; Kushch, N.D.; Buravov, L.I.; Khomenko, A.G.; Yagubskii, E.B.; Askenazy, S.; Pari, P.

1995-01-01

Temperature dependence of the resistivity in various crystallographic directions and high pulsed field magnetoresistance of organic metal α-(ET) 2 TlHg(SeCN) 4 have been studied at temperatures down to 80 mK. Giant Shubnikov-de Haas oscillations, which are attributed to the two-dimensional nature of the cylindrical Fermi surface with a very small warping along the direction of the lowest conductivity have been observed. Four harmonics of the fast oscillations with fundamental frequency F 0 =653±3 T and slow frequency oscillations with F s =38±5 T have been revealed. (orig.)

Frontal Alpha Oscillations and Attentional Control: A Virtual Reality Neurofeedback Study.

Science.gov (United States)

Berger, Anna M; Davelaar, Eddy J

2018-05-15

Two competing views about alpha oscillations suggest that cortical alpha reflect either cortical inactivity or cortical processing efficiency. We investigated the role of alpha oscillations in attentional control, as measured with a Stroop task. We used neurofeedback to train 22 participants to increase their level of alpha amplitude. Based on the conflict/control loop theory, we selected to train prefrontal alpha and focus on the Gratton effect as an index of deployment of attentional control. We expected an increase or a decrease in the Gratton effect with increase in neural learning depending on whether frontal alpha oscillations reflect cortical idling or enhanced processing efficiency, respectively. In order to induce variability in neural learning beyond natural occurring individual differences, we provided half of the participants with feedback on alpha amplitude in a 3-dimensional (3D) virtual reality environment and the other half received feedback in a 2D environment. Our results showed variable neural learning rates, with larger rates in the 3D compared to the 2D group, corroborating prior evidence of individual differences in EEG-based learning and the influence of a virtual environment. Regression analyses revealed a significant association between the learning rate and changes on deployment of attentional control, with larger learning rates being associated with larger decreases in the Gratton effect. This association was not modulated by feedback medium. The study supports the view of frontal alpha oscillations being associated with efficient neurocognitive processing and demonstrates the utility of neurofeedback training in addressing theoretical questions in the non-neurofeedback literature. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

The Lyapunov-Krasovskii theorem and a sufficient criterion for local stability of isochronal synchronization in networks of delay-coupled oscillators

Science.gov (United States)

Grzybowski, J. M. V.; Macau, E. E. N.; Yoneyama, T.

2017-05-01

This paper presents a self-contained framework for the stability assessment of isochronal synchronization in networks of chaotic and limit-cycle oscillators. The results were based on the Lyapunov-Krasovskii theorem and they establish a sufficient condition for local synchronization stability of as a function of the system and network parameters. With this in mind, a network of mutually delay-coupled oscillators subject to direct self-coupling is considered and then the resulting error equations are block-diagonalized for the purpose of studying their stability. These error equations are evaluated by means of analytical stability results derived from the Lyapunov-Krasovskii theorem. The proposed approach is shown to be a feasible option for the investigation of local stability of isochronal synchronization for a variety of oscillators coupled through linear functions of the state variables under a given undirected graph structure. This ultimately permits the systematic identification of stability regions within the high-dimensionality of the network parameter space. Examples of applications of the results to a number of networks of delay-coupled chaotic and limit-cycle oscillators are provided, such as Lorenz, Rössler, Cubic Chua's circuit, Van der Pol oscillator and the Hindmarsh-Rose neuron.

Reentrant behavior in the superconducting phase-dependent resistance of a disordered two-dimensional electron gas

NARCIS (Netherlands)

den Hartog, S.G.; Wees, B.J.van; Klapwijk, T.M; Nazarov, Y.V.; Borghs, G.

1997-01-01

We have investigated the bias-voltage dependence of the phase-dependent differential resistance of a disordered T-shaped two-dimensional electron gas coupled to two superconducting terminals. The resistance oscillations first increase upon lowering the energy. For bias voltages below the Thouless

Demonstration Of 3D Effects With High Gain And Efficiency In A UV FEL Oscillator

International Nuclear Information System (INIS)

Benson, Stephen; Biallas, George; Blackburn, Keith; Boyce, James; Bullard, Donald; Coleman, James; Dickover, Cody; Douglas, David; Ellingsworth, Forrest; Evtushenko, Pavel; Hernandez-Garcia, Carlos; Gould, Christopher; Gubeli, Joseph; Hardy, David; Jordan, Kevin; Klopf, John; Kortze, James; Legg, Robert; Marchlik, Matthew; Moore, Steven; Neil, George; Powers, Thomas; Sexton, Daniel; Shinn, Michelle; Tennant, Christopher; Walker, Richard; Watson, Anne; Williams, Gwyn; Wilson, Frederick; Zhang, Shukui

2011-01-01

We report on the performance of a high gain UV FEL oscillator operating on an energy recovery linac at Jefferson Lab. The high brightness of the electron beam leads to both gain and efficiency that cannot be reconciled with a one-dimensional model. Three-dimensional simulations do predict the performance with reasonable precision. Gain in excess of 100% per pass and an efficiency close to 1/2NW, where NW is the number of wiggler periods, is seen. The laser mirror tuning curves currently permit operation in the wavelength range of 438 to 362 nm. Another mirror set allows operation at longer wavelengths in the red with even higher gain and efficiency.

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...

Primordial oscillations in life: Direct observation of glycolytic oscillations in individual HeLa cervical cancer cells

Science.gov (United States)

Amemiya, Takashi; Shibata, Kenichi; Itoh, Yoshihiro; Itoh, Kiminori; Watanabe, Masatoshi; Yamaguchi, Tomohiko

2017-10-01

We report the first direct observation of glycolytic oscillations in HeLa cervical cancer cells, which we regard as primordial oscillations preserved in living cells. HeLa cells starved of glucose or both glucose and serum exhibited glycolytic oscillations in nicotinamide adenine dinucleotide (NADH), exhibiting asynchronous intercellular behaviors. Also found were spatially homogeneous and inhomogeneous intracellular NADH oscillations in the individual cells. Our results demonstrate that starved HeLa cells may be induced to exhibit glycolytic oscillations by either high-uptake of glucose or the enhancement of a glycolytic pathway (Crabtree effect or the Warburg effect), or both. Their asynchronous collective behaviors in the oscillations were probably due to a weak intercellular coupling. Elucidation of the relationship between the mechanism of glycolytic dynamics in cancer cells and their pathophysiological characteristics remains a challenge in future.

The su(2)α Hahn oscillator and a discrete Fourier-Hahn transform

International Nuclear Information System (INIS)

Jafarov, E I; Stoilova, N I; Van der Jeugt, J

2011-01-01

We define the quadratic algebra su(2) α which is a one-parameter deformation of the Lie algebra su(2) extended by a parity operator. The odd-dimensional representations of su(2) (with representation label j, a positive integer) can be extended to representations of su(2) α . We investigate a model of the finite one-dimensional harmonic oscillator based upon this algebra su(2) α . It turns out that in this model the spectrum of the position and momentum operator can be computed explicitly, and that the corresponding (discrete) wavefunctions can be determined in terms of Hahn polynomials. The operation mapping position wavefunctions into momentum wavefunctions is studied, and this so-called discrete Fourier-Hahn transform is computed explicitly. The matrix of this discrete Fourier-Hahn transform has many interesting properties, similar to those of the traditional discrete Fourier transform. (paper)

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 of the ampli......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...

Heat exchanger with oscillating flow

Science.gov (United States)

Scotti, Stephen J. (Inventor); Blosser, Max L. (Inventor); Camarda, Charles J. (Inventor)

1993-01-01

Various heat exchange apparatuses are described in which an oscillating flow of primary coolant is used to dissipate an incident heat flux. The oscillating flow may be imparted by a reciprocating piston, a double action twin reciprocating piston, fluidic oscillators or electromagnetic pumps. The oscillating fluid flows through at least one conduit in either an open loop or a closed loop. A secondary flow of coolant may be used to flow over the outer walls of at least one conduit to remove heat transferred from the primary coolant to the walls of the conduit.

Oscillations in stellar atmospheres

International Nuclear Information System (INIS)

Costa, A.; Ringuelet, A.E.; Fontenla, J.M.

1989-01-01

Atmospheric excitation and propagation of oscillations are analyzed for typical pulsating stars. The linear, plane-parallel approach for the pulsating atmosphere gives a local description of the phenomenon. From the local analysis of oscillations, the minimum frequencies are obtained for radially propagating waves. The comparison of the minimum frequencies obtained for a variety of stellar types is in good agreement with the observed periods of the oscillations. The role of the atmosphere in the globar stellar pulsations is thus emphasized. 7 refs

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

Transition from amplitude to oscillation death in a network of oscillators

International Nuclear Information System (INIS)

Nandan, Mauparna; Hens, C. R.; Dana, Syamal K.; Pal, Pinaki

2014-01-01

We report a transition from a homogeneous steady state (HSS) to inhomogeneous steady states (IHSSs) in a network of globally coupled identical oscillators. We perturb a synchronized population of oscillators in the network with a few local negative or repulsive mean field links. The whole population splits into two clusters for a certain number of repulsive mean field links and a range of coupling strength. For further increase of the strength of interaction, these clusters collapse into a HSS followed by a transition to IHSSs where all the oscillators populate either of the two stable steady states. We analytically determine the origin of HSS and its transition to IHSS in relation to the number of repulsive mean-field links and the strength of interaction using a reductionism approach to the model network. We verify the results with numerical examples of the paradigmatic Landau-Stuart limit cycle system and the chaotic Rössler oscillator as dynamical nodes. During the transition from HSS to IHSSs, the network follows the Turing type symmetry breaking pitchfork or transcritical bifurcation depending upon the system dynamics

Transition from amplitude to oscillation death in a network of oscillators