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Sample records for basilar membrane oscillation

  1. A Brownian Energy Depot Model of the Basilar Membrane Oscillation with a Braking Mechanism

    CERN Document Server

    Zhang, Yong; Lee, Kong-Ju-Bock; Park, Youngah

    2008-01-01

    High auditory sensitivity, sharp frequency selectivity, and otoacoustic emissions are signatures of active amplification of the cochlea. The human ear can also detect very large amplitude sound without being damaged as long as the exposed time is not too long. The outer hair cells are believed as the best candidate for the active force generator of the mammalian cochlea. In this paper, we propose a new model for the basilar membrane oscillation which successfully describes both the active and the protective mechanisms by employing an energy depot concept and a critical velocity of the basilar membrane. One of the main results is that thermal noise in the absence of external stimulation can be amplified leading to the spontaneous basilar membrane oscillation. The compressive response of the basilar membrane at the characteristic frequency and the dynamic response to the stimulation are consistent with the experimental results as expected. Our model also shows the nonlinear distortion of the response of the bas...

  2. Mechanics of the basilar membrane in Caiman crocodilus.

    Science.gov (United States)

    Wilson, J P; Smolders, J W; Klinke, R

    1985-04-01

    Vibration measurements were made at a number of positions near the proximal (basal) end of the basilar membrane, and on the columella footplate, of Caiman crocodilus using a capacitive probe. The measurements established the existence of a mechanical travelling wave in this species. They showed no significant change of mechanical tuning with temperature, and were highly significantly different from previous reports of neural temperature sensitivity (Smolders, J. and Klinke, R. (1984): J. Comp. Physiol. 155, 19-30). Thus the neural sensitivity to temperature change appears not to depend upon basilar membrane mechanics. One interpretation of this is that the basilar membrane passively precedes an active temperature-sensitive filter. It was also found that the limbus supporting the basilar membrane had a measurable, but unturned, vibration and that the effect of draining scala tympani for the measurements was to increase the basilar membrane tuning frequency by a factor of about 1.5.

  3. Are active elements necessary in the basilar membrane impedance?

    Science.gov (United States)

    Diependaal, R J; Viergever, M A; de Boer, E

    1986-07-01

    This article is motivated by the current hypothesis [Kim et al., Psychological, Physiological and Behavioural Studies in Hearing (Delft U. P., The Netherlands, 1980); Neely, Doctoral dissertation, Washington University, St. Louis, MO (1981); de Boer, J. Acoust. Soc. Am. 73, 567-573 (1983a) and 73, 574-576 (1983b)] that it is necessary to include active elements in the basilar membrane (BM) impedance in order to explain recent data on the vibration of the BM [Khanna and Leonard, Science 215, 305-306 (1982); Sellick et al., J. Acoust. Soc. Am. 72, 131-141 (1982); Robles et al., Peripheral Auditory Mechanisms (Springer, New York, 1986)]. In order to test this hypothesis, first, a method which is an inversion of the customary description of cochlear mechanics is described. Instead of computing the BM velocity for a given point impedance of the membrane, we show how to compute the impedance function from a given BM velocity pattern in response to a sinusoidal input at the stapes. This method is then used to study the sensitivity of the recovered impedance to perturbations in the velocity pattern. The simulations used show that the real part of the impedance is extremely sensitive to such perturbations. Therefore, measured velocity patterns are unlikely to resolve the issue of whether active elements should be included. Frequency responses measured at a few points on the membrane are even less likely to do so.

  4. Analysis of an impulse response measured at the basilar membrane of the chinchilla (L)

    NARCIS (Netherlands)

    Wit, Hero P.; Bell, Andrew

    2015-01-01

    In a recent paper [J. Acoust. Soc. Am. 133, 2224-2239 (2013)], Shera and Cooper report on the impulse response of the basilar membrane (BM) of a chinchilla, a waveform which shows repetitive bursts. They explain the bursts in terms of repeated coherent reflection at BM discontinuities and partial re

  5. Electrically evoked reticular lamina and basilar membrane vibrations in mice with alpha tectorin C1509G mutation

    Science.gov (United States)

    Ren, Tianying; He, Wenxuan

    2015-12-01

    Mechanical coupling between the tectorial membrane and the hair bundles of outer hair cells is crucial for stimulating mechanoelectrical transduction channels, which convert sound-induced vibrations into electrical signal, and for transmitting outer hair cell-generated force back to the basilar membrane to boost hearing sensitivity. It has been demonstrated that the detached tectorial membrane in mice with C1509G alpha tectorin mutation caused hearing loss, but enhanced electrically evoked otoacoustic emissions. To understand how the mutated cochlea emits sounds, the reticular lamina and basilar membrane vibrations were measured in the electrically stimulated cochlea in this study. The results showed that the electrically evoked basilar membrane vibration decreased dramatically while the reticular lamina vibration and otoacoustic emissions exhibited no significant change in C1509G mutation mice. This result indicates that a functional cochlear amplifier and a normal basilar membrane vibration are not required for the outer hair cell-generated sound to exit the cochlea.

  6. Noninvasive in vivo imaging reveals differences between tectorial membrane and basilar membrane traveling waves in the mouse cochlea.

    Science.gov (United States)

    Lee, Hee Yoon; Raphael, Patrick D; Park, Jesung; Ellerbee, Audrey K; Applegate, Brian E; Oghalai, John S

    2015-03-10

    Sound is encoded within the auditory portion of the inner ear, the cochlea, after propagating down its length as a traveling wave. For over half a century, vibratory measurements to study cochlear traveling waves have been made using invasive approaches such as laser Doppler vibrometry. Although these studies have provided critical information regarding the nonlinear processes within the living cochlea that increase the amplitude of vibration and sharpen frequency tuning, the data have typically been limited to point measurements of basilar membrane vibration. In addition, opening the cochlea may alter its function and affect the findings. Here we describe volumetric optical coherence tomography vibrometry, a technique that overcomes these limitations by providing depth-resolved displacement measurements at 200 kHz inside a 3D volume of tissue with picometer sensitivity. We studied the mouse cochlea by imaging noninvasively through the surrounding bone to measure sound-induced vibrations of the sensory structures in vivo, and report, to our knowledge, the first measures of tectorial membrane vibration within the unopened cochlea. We found that the tectorial membrane sustains traveling wave propagation. Compared with basilar membrane traveling waves, tectorial membrane traveling waves have larger dynamic ranges, sharper frequency tuning, and apically shifted positions of peak vibration. These findings explain discrepancies between previously published basilar membrane vibration and auditory nerve single unit data. Because the tectorial membrane directly overlies the inner hair cell stereociliary bundles, these data provide the most accurate characterization of the stimulus shaping the afferent auditory response available to date.

  7. Development of a Multi-Channel Piezoelectric Acoustic Sensor Based on an Artificial Basilar Membrane

    Directory of Open Access Journals (Sweden)

    Youngdo Jung

    2013-12-01

    Full Text Available In this research, we have developed a multi-channel piezoelectric acoustic sensor (McPAS that mimics the function of the natural basilar membrane capable of separating incoming acoustic signals mechanically by their frequency and generating corresponding electrical signals. The McPAS operates without an external energy source and signal processing unit with a vibrating piezoelectric thin film membrane. The shape of the vibrating membrane was chosen to be trapezoidal such that different locations of membrane have different local resonance frequencies. The length of the membrane is 28 mm and the width of the membrane varies from 1 mm to 8 mm. Multiphysics finite element analysis (FEA was carried out to predict and design the mechanical behaviors and piezoelectric response of the McPAS model. The designed McPAS was fabricated with a MEMS fabrication process based on the simulated results. The fabricated device was tested with a mouth simulator to measure its mechanical and piezoelectrical frequency response with a laser Doppler vibrometer and acoustic signal analyzer. The experimental results show that the as fabricated McPAS can successfully separate incoming acoustic signals within the 2.5 kHz–13.5 kHz range and the maximum electrical signal output upon acoustic signal input of 94 dBSPL was 6.33 mVpp. The performance of the fabricated McPAS coincided well with the designed parameters.

  8. Modeling two-tone suppression and distortion product on basilar membrane

    Science.gov (United States)

    Murakami, Yasuki; Ishimitsu, Shunsuke

    2015-12-01

    This paper reveals mechanisms of two-tone suppression (2TS) and distortion product (DP) on the basilar membrane (BM) using a model. Computational simulation is conducted with an active and nonlinear transmission line model including a nonlinear outer hair cell model that shows compressive property in two dimensionally where two tones are input. To evaluate the cochlear model, over all responses of BM model are used. For simultaneous input pairs, the response is suppressed by a stronger tone, or distorted where levels of a pair are equaled. Cubic distortion produced by a simple nonlinear feedback system including the OHC model appears similar to DPs in the cochlear model. These results suggest that two dimensional property of the OHC and its feedback generate 2TS and DPs. This further suggests the importance of the overall responses for investigating mechanisms of cochlear nonlinearities without fluid coupling in the cochlea.

  9. Behavioral estimates of basilar-membrane input-output in normal-hearing listeners

    DEFF Research Database (Denmark)

    Jepsen, Morten Løve; Dau, Torsten

    2011-01-01

    To characterize human cochlear processing it would be beneficial to behaviorally estimate the basilar membrane (BM) input-output (I/O) function. In recent studies, forward masking has been used to estimate BM compression. In this study, a growth-of-forward-masking (GOM) paradigm (e.g., Oxenham...... function is expected than that obtained for a high-level signal where both masker and signal are processed compressively. The knee point can be estimated at the input level where the GOM slope changes significantly. Data were collected from seven normal - hearing listeners. The method was found to provide...... estimates of the BM I/O function for a wider range of input levels than in previously suggested methods, due to the additional estimates of the knee points....

  10. Effect of different stapes prostheses on the passive vibration of the basilar membrane.

    Science.gov (United States)

    Kwacz, Monika; Marek, Piotr; Borkowski, Paweł; Gambin, Wiktor

    2014-04-01

    The effect of different stapes prostheses on the basilar membrane (BM) motion was determined. To that end, a three dimensional finite element (FE) model of the passive human cochlea was developed. Passive responses of the BM were found based on coupled fluid-structure interactions between the cochlear solid structures and the scala fluids. The passive BM vibrations in normal (healthy) cochlea were compared with vibrations in the cochlea in which a 0.4-mm piston or a proposed new type of prosthesis was implanted. The proposed chamber prosthesis was not experimentally implanted, but only numerically simulated. Design of the new chamber stapes prosthesis is presented for the first time in this paper. The simulation results showed 10-20 dB decrease in BM displacement amplitude in the case of the piston. In contrast, the BM responses in the cochlea with the new prosthesis are higher with respect to the healthy ear. The results obtained in this study are promising for further research to optimize the design of the new chamber stapes prosthesis.

  11. Resultant pressure distribution pattern along the basilar membrane in the spiral shaped cochlea

    CERN Document Server

    Zhang, Yong; Lee, Kong-Ju-Bock; Park, Youngah

    2008-01-01

    Cochlea is an important auditory organ in the inner ear. In most mammals, it is coiled as a spiral. Whether this specific shape influences hearing is still an open problem. By employing a three dimensional fluid model of the cochlea with an idealized geometry, the influence of the spiral geometry of the cochlea is examined. We obtain solutions of the model through a conformal transformation in a long-wave approximation. Our results show that the net pressure acting on the basilar membrane is not uniform along its spanwise direction. Also, it is shown that the location of the maximum of the spanwise pressure difference in the axial direction has a mode dependence. In the simplest pattern, the present result is consistent with the previous theory based on the WKB-like approximation [D. Manoussaki, Phys. Rev. Lett. 96, 088701(2006)]. In this mode, the pressure difference in the spanwise direction is a monotonic function of the distance from the apex and the normal velocity across the channel width is zero. Thus ...

  12. Near field fluid coupling between internal motion of the organ of Corti and the basilar membrane

    Energy Technology Data Exchange (ETDEWEB)

    Elliott, Stephen J.; Ni, Guangjian [Institute of Sound and Vibration Research, University of Southampton, Southampton (United Kingdom)

    2015-12-31

    The pressure distribution in each of the fluid chambers of the cochlea can be decomposed into a 1D, or plane wave, component and a near field component, which decays rapidly away from the excitation point. The transverse motion of the basilar membrane, BM, for example, generates both a 1D pressure field, which couples into the slow wave, and a local near field pressure, proportional to the BM acceleration, that generates an added mass on the BM due to the fluid motion. When the organ of Corti, OC, undergoes internal motion, due for example to outer hair cell activity, this motion will not itself generate any 1D pressure if the OC is incompressible and the BM is constrained not to move volumetrically, and so will not directly couple into the slow wave. This motion will, however, generate a near field pressure, proportional to the OC acceleration, which will act on the OC and thus increases its effective mass. The near field pressure due to this OC motion will also act on the BM, generating a force on the BM proportional to the acceleration of the OC, and thus create a “coupling mass” effect. By reciprocity, this coupling mass is the same as that acting on the OC due to the motion of the BM. This near field fluid coupling is initially observed in a finite element model of a slice of the cochlea. These simulations suggest a simple analytical formulation for the fluid coupling, using higher order beam modes across the width of the cochlear partition. It is well known that the added mass due to the near field pressure dominates the overall mass of the BM, and thus significantly affects the micromechanical dynamics. This work not only quantifies the added mass of the OC due its own motion in the fluid, and shows that this is important, but also demonstrates that the coupling mass effect between the BM and OC significantly affects the dynamics of simple micromechanical models.

  13. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were prod

  14. Estimating the basilar-membrane input-output function in normal-hearing and hearing-impaired listeners

    DEFF Research Database (Denmark)

    Jepsen, Morten Løve; Dau, Torsten

    To partly characterize the function of cochlear processing in humans, the basilar membrane (BM) input-output function can be estimated. In recent studies, forward masking has been used to estimate BM compression. If an on-frequency masker is processed compressively, while an off-frequency masker...... processing at medium levels. If a signal can be masked by a low-level on-frequency masker such that signal and masker fall in the linear region of the I/O-function, then a steeper GOM function is expected. The knee-point can then be estimated in the input level region where the GOM changes significantly...... higher input levels and compression was similar to that of NH listeners....

  15. Symmetry-breaking oscillations in membrane optomechanics

    Science.gov (United States)

    Wurl, C.; Alvermann, A.; Fehske, H.

    2016-12-01

    We study the classical dynamics of a membrane inside a cavity in the situation where this optomechanical system possesses a reflection symmetry. Symmetry breaking occurs through supercritical and subcritical pitchfork bifurcations of the static fixed-point solutions. Both bifurcations can be observed through variation of the laser-cavity detuning, which gives rise to a boomerang-like fixed-point pattern with hysteresis. The symmetry-breaking fixed points evolve into self-sustained oscillations when the laser intensity is increased. In addition to the analysis of the accompanying Hopf bifurcations we describe these oscillations at finite amplitudes with an ansatz that fully accounts for the frequency shift relative to the natural membrane frequency. We complete our study by following the route to chaos for the membrane dynamics.

  16. Degenerate parametric oscillation in quantum membrane optomechanics

    Science.gov (United States)

    Benito, Mónica; Sánchez Muñoz, Carlos; Navarrete-Benlloch, Carlos

    2016-02-01

    The promise of innovative applications has triggered the development of many modern technologies capable of exploiting quantum effects. But in addition to future applications, such quantum technologies have already provided us with the possibility of accessing quantum-mechanical scenarios that seemed unreachable just a few decades ago. With this spirit, in this work we show that modern optomechanical setups are mature enough to implement one of the most elusive models in the field of open system dynamics: degenerate parametric oscillation. Introduced in the eighties and motivated by its alleged implementability in nonlinear optical resonators, it rapidly became a paradigm for the study of dissipative phase transitions whose corresponding spontaneously broken symmetry is discrete. However, it was found that the intrinsic multimode nature of optical cavities makes it impossible to experimentally study the model all the way through its phase transition. In contrast, here we show that this long-awaited model can be implemented in the motion of a mechanical object dispersively coupled to the light contained in a cavity, when the latter is properly driven with multichromatic laser light. We focus on membranes as the mechanical element, showing that the main signatures of the degenerate parametric oscillation model can be studied in state-of-the-art setups, thus opening the possibility of analyzing spontaneous symmetry breaking and enhanced metrology in one of the cleanest dissipative phase transitions. In addition, the ideas put forward in this work would allow for the dissipative preparation of squeezed mechanical states.

  17. Probing glycolytic and membrane potential oscillations in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Poulsen, Allan K.; Andersen, Ann Zahle; Brasen, Jens Christian

    2008-01-01

    , while mitochondrial membrane potential was measured using the fluorescent dye DiOC(2)(3). The results show that, as opposed to NADH and other intermediates in glycolysis, intracellular glucose is not oscillating. Furthermore, oscillations in NADH and membrane potential are inhibited by the ATP...

  18. Oscillations and multiple steady states in active membrane transport models.

    Science.gov (United States)

    Vieira, F M; Bisch, P M

    1994-01-01

    The dynamic behavior of some non-linear extensions of the six-state alternating access model for active membrane transport is investigated. We use stoichio-metric network analysis to study the stability of steady states. The bifurcation analysis has been done through standard numerical methods. For the usual six-state model we have proved that there is only one steady state, which is globally asymptotically stable. When we added an autocatalytic step we found self-oscillations. For the competition between a monomer cycle and a dimer cycle, with steps of dimer formation, we have also found self-oscillations. We have also studied models involving the formation of a complex with other molecules. The addition of two steps for formation of a complex of the monomer with another molecule does not alter either the number or the stability of steady states of the basic six-state model. The model which combines the formation of a complex with an autocatalytic step shows both self-oscillations and multiple steady states. The results lead us to conclude that oscillations could be produced by active membrane transport systems if the transport cycle contains a sufficiently large number of steps (six in the present case) and is coupled to at least one autocatalytic reaction,. Oscillations are also predicted when the monomer cycle is coupled to a dimer cycle. In fact, the autocatalytic reaction can be seen as a simplification of the model involving competition between monomer and dimer cycles, which seems to be a more realistic description of biological systems. A self-regulation mechanism of the pumps, related to the multiple stationary states, is expected only for a combined effect of autocatalysis and formation of complexes with other molecules. Within the six-state model this model also leads to oscillation.

  19. Traumatic basilar pseudoaneurysm with a basilar-cavernous arteriovenous fistula

    Energy Technology Data Exchange (ETDEWEB)

    Connor, S.E.J.; Deasy, N.P.; Jeffree, M.A. [Dept. of Neuroradiology, King' s Coll. Hospital, London (United Kingdom); Martin, A.J.; Strong, A.J. [Dept. of Neurosurgery, King' s Coll. Hospital, London (United Kingdom)

    2001-03-01

    A traumatic pseudoaneurysm of the basilar artery with a basilar-cavernous sinus arteriovenous fistula was diagnosed in a 12-year-old girl using CT, MRI and angiography. It was successfully treated by coil embolisation. We speculate on the mode of formation of this rare traumatic lesion. (orig.)

  20. A new approach to the spectral analysis of liquid membrane oscillators by Gábor transformation

    DEFF Research Database (Denmark)

    Płocharska-Jankowska, E.; Szpakowska, M.; Mátéfi-Tempfli, Stefan;

    2006-01-01

    Liquid membrane oscillators very frequently have an irregular oscillatory behavior. Fourier transformation cannot be used for these nonstationary oscillations to establish their power spectra. This important point seems to be overlooked in the field of chemical oscillators. A new approach...... is presented here based on Gábor transformation allowing one to obtain power spectra of any kind of oscillations that can be met experimentally. The proposed Gábor analysis is applied to a liquid membrane oscillator containing a cationic surfactant. It was found that the power spectra are strongly influenced...

  1. Threshold for spontaneous oscillation in a three-phase liquid membrane system involving nonionic surfactant.

    Science.gov (United States)

    Nanzai, Ben; Funazaki, Tomohisa; Igawa, Manabu

    2010-09-16

    This study of self-oscillation was conducted using a new three-phase liquid membrane system of ethanol aqueous solution, benzyl alcohol solution with nonionic surfactant, and pure water. Relations of the initial ethanol concentration to the oscillation amplitude and frequency, and to the induction period before oscillations were investigated. The oscillation amplitude is independent of the initial ethanol concentration, but the frequency and the induction period are related to it. The oscillation frequency increased concomitantly with the increased ethanol initial concentration, but the induction period before the electrical oscillations decreased with increasing concentration. To estimate the influence of ethanol diffusion on the electrical oscillations, the ethanol concentration in each phase was measured using separate experiments after different durations of oscillation. The diffusion coefficient was calculated using Fick's second law. Results show successful estimation of the threshold for oscillations. The threshold is defined in terms of the ethanol concentration at the interface between the benzyl alcohol phase and the pure water phase.

  2. On-line measurements of oscillating mitochondrial membrane potential in glucose-fermenting Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Andersen, Ann Zahle; Poulsen, Allan K; Olsen, Lars Folke

    2007-01-01

    We employed the fluorescent cyanine dye DiOC(2)(3) to measure membrane potential in semi-anaerobic yeast cells under conditions where glycolysis was oscillating. Oscillations in glycolysis were studied by means of the naturally abundant nicotinamide adenine dinucleotide (NADH). We found that the ......We employed the fluorescent cyanine dye DiOC(2)(3) to measure membrane potential in semi-anaerobic yeast cells under conditions where glycolysis was oscillating. Oscillations in glycolysis were studied by means of the naturally abundant nicotinamide adenine dinucleotide (NADH). We found...

  3. Study on the oscillating phenomena of electrical potential across a liquid membrane

    Institute of Scientific and Technical Information of China (English)

    Jin Zhang Gao; Hong Xia Dai; Hua Chen; Jie Ren; Wu Yang

    2007-01-01

    The electrical oscillations across a liquid membrane in water/oil/water system was studied with octanol as oil phase by introducing two opposite charged surfactants in oil and aqueous phase, respectively. The sustained and rhythmic oscillation was observed. To a certain extent, the features of the oscillation (e.g. induction time, frequency, life time and orientation of the pulse pikes) strongly depend on the property of surfactant, dissolved in octanol. The mechanism may be explained by the formation and destruction of dual-ion surfactant membrane accompanying with emulsification at the interface and considering the coupling effect of diffusion and associated reaction in the vicinity of the interface.

  4. 一氧化氮合酶阻断剂对豚鼠耳蜗基底膜振动速度的影响%Effect of nitric oxide synthase blockade on basilar membrane velocity in guinea pigs cochlea

    Institute of Scientific and Technical Information of China (English)

    郭梦和; 黄以乐

    1999-01-01

    目的:观察N-甲基-左旋精氨酸(L-NNA)对基底膜振动速度(velocity of basilar membrane vibration, BMV)的影响,了解一氧化氮(NO)对耳蜗外毛细胞(cochlear outer hair cells, COHCs)的作用.方法:杂色豚鼠25只,麻醉、手术准备后用1.6 mmol/L的L-NNA 8 μL行耳蜗底圈鼓阶内灌注,测试BMV、听神经复合动作电位(cAP)、蜗内电位(EP),记录用直流电脉冲诱发的BMV.结果:蜗内灌注L-NNA后,BMV大约提高了3倍,耳蜗微音器电位振幅略有下降,而EP无明显变化.这一现象只出现在耳蜗灵敏度仅有轻微下降情况下,正常听敏度耳蜗或耳蜗功能严重损伤时BMV无提高作用.结论:NO可能促使耳蜗的声损伤加重,L-NNA可阻断NO的合成,从而起到保护耳蜗的作用.

  5. Regulation of glycolytic oscillations by mitochondrial and plasma membrane H+-ATPases

    DEFF Research Database (Denmark)

    Olsen, Lars Folke; Andersen, Ann Zahle; Lunding, Anita

    2009-01-01

    We investigated the coupling between glycolytic and mitochondrial membrane potential oscillations in Saccharomyces cerevisiae under semianaerobic conditions. Glycolysis was measured as NADH autofluorescence, and mitochondrial membrane potential was measured using the fluorescent dye 3,3'-diethylo......We investigated the coupling between glycolytic and mitochondrial membrane potential oscillations in Saccharomyces cerevisiae under semianaerobic conditions. Glycolysis was measured as NADH autofluorescence, and mitochondrial membrane potential was measured using the fluorescent dye 3......,3'-diethyloxacarbocyanine iodide. The responses of glycolytic and membrane potential oscillations to a number of inhibitors of glycolysis, mitochondrial electron flow, and mitochondrial and plasma membrane H(+)-ATPase were investigated. Furthermore, the glycolytic flux was determined as the rate of production of ethanol...... in a number of different situations (changing pH or the presence and absence of inhibitors). Finally, the intracellular pH was determined and shown to oscillate. The results support earlier work suggesting that the coupling between glycolysis and mitochondrial membrane potential is mediated by the ADP...

  6. Flowfield-induced oscillations of a flexible membrane

    Science.gov (United States)

    Davis, Michael; Smits, Alexander

    1998-11-01

    Preliminary experiments are reported on the interaction between a flexible membrane and the wake flow generated by a bluff body. The bluff body generates a strong vortex sheet, and as the vortices pass over the membrane a traveling flexural wave develops in the membrane, causing it to flap. The amplitude and frequeny of the flapping is a function of the size, shape and position of the bluff body, the velocity of the flow, the size, shape, and material properties of the membrane. Experiments designed to maximize the frequency and amplitude of the flapping are reported for a variety of membrane constructions, with an eye to optimizing power generation by the flexing of the piezo-electric materials used in the construction of the membrane.

  7. Oculomotor Paresis and Basilar Aneurysm

    OpenAIRE

    J Gordon Millichap

    1992-01-01

    The clinical and pathologic findings in a 10 month old girl with congenital heart diseasewho died after rupture of a congenital distal basilar artery aneurysm are reported from the University of Connecticut Health Center, Farmington, CT and the Children’s Hospital of Philadelphia, PA.

  8. Membrane Bistability in Thalamic Reticular Neurons During Spindle Oscillations

    Science.gov (United States)

    Fuentealba, Pablo; Timofeev, Igor; Bazhenov, Maxim; Sejnowski, Terrence J.; Steriade, Mircea

    2010-01-01

    The thalamic reticular (RE) nucleus is a major source of inhibition in the thalamus. It plays a crucial role in regulating the excitability of thalamocortical networks and in generating some sleep rhythms. Current-clamp intracellular recordings of RE neurons in cats under barbiturate anesthesia revealed the presence of membrane bistability in ~20% of neurons. Bistability consisted of two alternate membrane potentials, separated by ~17–20 mV. While non-bistable (common) RE neurons fired rhythmic spike-bursts during spindles, bistable RE neurons fired tonically, with burst modulation, throughout spindle sequences. Bistability was strongly voltage dependent and only expressed under resting conditions (i.e. no current injection). The transition from the silent to the active state was a regenerative event that could be activated by brief depolarization, whereas brief hyperpolarizations could switch the membrane potential from the active to the silent state. These effects outlasted the current pulses. Corticothalamic stimulation could also switch the membrane potential from silent to active states. Addition of QX-314 in the recording micropipette either abolished or disrupted membrane bistability, suggesting INa(p) to be responsible for its generation. Thalamocortical cells presented various patterns of spindling that reflected the membrane bistability in RE neurons. Finally, experimental data and computer simulations predicted a role for RE neurons’ membrane bistability in inducing various patterns of spindling in target thalamocortical cells. We conclude that membrane bistability of RE neurons is an intrinsic property, likely generated by INa(p) and modulated by cortical influences, as well as a factor that determines different patterns of spindle rhythms in thalamocortical neurons. PMID:15331618

  9. Long-range correlation of the membrane potential in neocortical neurons during slow oscillation

    Science.gov (United States)

    Volgushev, Maxim; Chauvette, Sylvain; Timofeev, Igor

    2012-01-01

    Large amplitude slow waves are characteristic for the summary brain activity, recorded as electroencephalogram (EEG) or local field potentials (LFP), during deep stages of sleep and some types of anesthesia. Slow rhythm of the synchronized EEG reflects an alternation of active (depolarized, UP) and silent (hyperpolarized, DOWN) states of neocortical neurons. In neurons, involvement in the generalized slow oscillation results in a long-range synchronization of changes of their membrane potential as well as their firing. Here, we aimed at intracellular analysis of details of this synchronization. We asked which components of neuronal activity exhibit long-range correlations during the synchronized EEG? To answer this question, we made simultaneous intracellular recordings from two to four neocortical neurons in cat neocortex. We studied how correlated is the occurrence of active and silent states, and how correlated are fluctuations of the membrane potential in pairs of neurons located close one to the other or separated by up to 13 mm. We show that strong long-range correlation of the membrane potential was observed only (i) during the slow oscillation but not during periods without the oscillation, (ii) during periods which included transitions between the states but not during within-the-state periods, and (iii) for the low-frequency (10 Hz). In contrast to the neurons located several millimeters one from the other, membrane potential fluctuations in neighboring neurons remain strongly correlated during periods without slow oscillation. We conclude that membrane potential correlation in distant neurons is brought about by synchronous transitions between the states, while activity within the states is largely uncorrelated. The lack of the generalized fine-scale synchronization of membrane potential changes in neurons during the active states of slow oscillation may allow individual neurons to selectively engage in short living episodes of correlated activity

  10. Hair cell force generation does not amplify or tune vibrations within the chicken basilar papilla.

    Science.gov (United States)

    Xia, Anping; Liu, Xiaofang; Raphael, Patrick D; Applegate, Brian E; Oghalai, John S

    2016-10-31

    Frequency tuning within the auditory papilla of most non-mammalian species is electrical, deriving from ion-channel resonance within their sensory hair cells. In contrast, tuning within the mammalian cochlea is mechanical, stemming from active mechanisms within outer hair cells that amplify the basilar membrane travelling wave. Interestingly, hair cells in the avian basilar papilla demonstrate both electrical resonance and force-generation, making it unclear which mechanism creates sharp frequency tuning. Here, we measured sound-induced vibrations within the apical half of the chicken basilar papilla in vivo and found broadly-tuned travelling waves that were not amplified. However, distortion products were found in live but not dead chickens. These findings support the idea that avian hair cells do produce force, but that their effects on vibration are small and do not sharpen tuning. Therefore, frequency tuning within the apical avian basilar papilla is not mechanical, and likely derives from hair cell electrical resonance.

  11. Electroencephalograms in basilar artery migraine.

    Science.gov (United States)

    Parain, D; Samson-Dollfus, D

    1984-11-01

    Nine cases of 'basilar artery migraine' (BAM) have been recorded. In 8 cases, excess of beta activity was observed during the attacks and disappeared in less than 3 days. The inter-ictal EEGs were normal. Drug ingestion was excluded each time. These EEG patterns are different from those which have been reported in the literature, i.e., transitory posterior abnormal slow waves. However, case no.1 is in agreement with the literature. The expression 'BAM' probably covers different syndromes which are further discussed.

  12. Basilar invagination, Chiari malformation, syringomyelia: A review

    Directory of Open Access Journals (Sweden)

    Goel Atul

    2009-01-01

    Full Text Available Institute and personal experience (over 25 years of basilar invagination was reviewed. The database of the department included 3300 patients with craniovertebral junction pathology from the year 1951 till date. Patients with basilar invagination were categorized into two groups based on the presence (Group A or absence (Group B of clinical and radiological evidence of instability of the craniovertebral junction. Standard radiological parameters described by Chamberlain were used to assess the instability of the craniovertebral junction. The pathogenesis and clinical features in patients with Group A basilar invagination appeared to be related to mechanical instability, whereas it appeared to be secondary to embryonic dysgenesis in patients with Group B basilar invagination. Treatment by facetal distraction and direct lateral mass fixation can result in restoration of craniovertebral and cervical alignment in patients with Group A basilar invagination. Such a treatment can circumvent the need for transoral or posterior fossa decompression surgery. Foramen magnum bone decompression appears to be a rational surgical treatment for patients having Group B basilar invagination. The division of patients with basilar invagination on the basis of presence or absence of instability provides insight into the pathogenesis of the anomaly and a basis for rational surgical treatment.

  13. Subthreshold membrane-potential oscillations in immature rat CA3 hippocampal neurones.

    Science.gov (United States)

    Psarropoulou, C; Avoli, M

    1995-12-15

    Subthreshold membrane potential oscillations (MPOs) were recorded intracellularly in 31 of 43 (>70%) immature CA3 hippocampal neurones (from 3-17 days postnatally). MPOs (3-5 mV, 3-15 Hz) occurred at resting membrane potential (RMP) in 20 of 31 neurones, or following depolarization (11 of 31 neurones); with sufficient depolarization spontaneous action potentials (APs) were generated from the positive-going phase of MPOs. In all cells, MPOs were blocked by steady membrane hyperpolarization. Tetrodotoxin abolished MPOs (n = 4); Co(2+) markedly reduced them (n = 3), and tetraethylammonium, added in the presence of TTX, revealed lower frequency oscillatory activity (n = 2). We conclude that subthreshold MPOs in immature hippocampus, possibly linked to theta rhythm generation and memory acquisition, depend on voltage-dependent Na+ electrogenesis and they might be additionally controlled by Ca(2+) and K+ conductances.

  14. SIMULATION OF THE LIGHT-INDUCED OSCILLATIONS OF THE MEMBRANE-POTENTIAL IN POTAMOGETON LEAF-CELLS

    NARCIS (Netherlands)

    MIEDEMA, H; PRINS, HBA

    1993-01-01

    An attempt has been made to simulate the light-induced oscillations of the membrane potential of Potamogeton lucens leaf cells in relation to the apoplastic pH changes. Previously it was demonstrated that the membrane potential of these cells can be described in terms of proton movements only. It is

  15. Synchronous plasma membrane electrochemical potential oscillations during yeast colony development and aging.

    Science.gov (United States)

    Palková, Zdena; Váchová, Libuse; Gásková, Dana; Kucerová, Helena

    2009-05-01

    Microorganisms that survive in natural environments form organized multicellular communities, biofilms and colonies with specific properties. During stress and nutrient limitation, slow growing and senescent cells in such communities retain vital processes by maintaining plasma membrane integrity and retaining the ability to generate transmembrane electrochemical gradients. We report the use of a Saccharomyces cerevisiae colonial model to show that population growth in a multicellular community depends on nutrient diffusion and that resting cells start to accumulate from the beginning of the second acidic phase of colony development. Despite differentiation of colony members, synchronous transmembrane potential oscillation was detected in the organized colony. The electrochemical membrane potential periodically oscillated at frequencies between those for circadian to infradian rhythms during colony aging and transiently decreased at time points previously linked with rebuilding of yeast metabolism. Despite extensive decreases in the intracellular ATP concentration and in the amount and activity of the plasma membrane proton pump during nutrient limited growth and colony aging, the transmembrane electrochemical potential appeared to be maintained above a level critical for population survival.

  16. 新型液膜振荡器%New Type of Liquid Membrane Oscillator

    Institute of Scientific and Technical Information of China (English)

    贺占博; 阎喜龙; 聂玉敏; 张凤才

    1999-01-01

    A new type of liquid membrane oscillator in which non-ionic surfactant is the key component was designed in a U type tube and monitored by a pair of Pt electrodes.The fundamental composition is 1.0% emulsifier OP (aq)/n-butanol:nitrobenzene=1∶5(V/V)/0.5mol· dm-3 NaCl(aq).The molecular formula of emulsifier OP is C8H17 ◎O(CH2CH2O)10H.The mechanism and influence factors were studied by replacing component,changing concentration,adding additive,comparison between different experimental apparatus and auxiliary experiment.The oscillatory mechanism is repetitive formation and abrupt destruction of interface membrane of the surfactant,induced by hydrogen bond between n-butanol and emulsifier OP.

  17. Coupled, Active Oscillators and Lizard Otoacoustic Emissions

    Science.gov (United States)

    Bergevin, Christopher; Velenovsky, David S.; Bonine, Kevin E.

    2011-11-01

    The present study empirically explores the relationship between spontaneous otoacoustic emissions (SOAEs) and stimulus-frequency emissions (SFOAEs) in lizards, an ideal group for such research given their relatively simple inner ear (e.g., lack of basilar membrane traveling waves), diverse morphology across species/families (e.g., tectorial membrane structure) and robust emissions. In a nutshell, our results indicate that SFOAEs evoked using low-level tones are intimately related to underlying SOAE activity, and appear to represent the entrained response of active oscillators closely tuned to the probe frequency. The data described here indicate several essential features that are desirable to capture in theoretical models for auditory transduction in lizards, and potentially represent generic properties at work in many different classes of "active" ears.

  18. Hipnoticos corticales y basilares y acciones anticonvulsivantes

    OpenAIRE

    Carlos Gutiérrez-Noriega

    2013-01-01

    Se estudian las diferencias de los hipnóticos corticales y basilares desde el punto de vista de sus acciones anticonvulsivantes. Los resultados son los siguientes: 1. Los hipnóticos del grupo basilar (barbitúrico y uretano) poseen un poder anticonvulsivante considerablemente mayor que los hipnóticos del grupo cortical (alcoholes, aldehidos, bromuros, éter), con excepción del sulfato de magnesia, clasificado en el grupo subcortical, que tiene muy poca acción anticonvulsivante. 2. Algunos hipnó...

  19. Study on the liquid membrane oscillation of water/oil/water system containing TTAB and picric acid

    Institute of Scientific and Technical Information of China (English)

    Li Zhou; Jiao Ning Tang; Bo Liu; Yi Guang Wu; Ai Lian Wang; Chuan Dong Liao

    2008-01-01

    The liquid membrane oscillation of a novel water (aqueous tetradecyl trimethyl ammoniumbromide,TTAB and alcohol sohition)/oil (picdcacid in chloroform sohition)/water (aqueous glucose solution) system was investigated.By using homemade device,the curves of various liquid membranes oscillation with different concentration of TTAB and picric acid,types of alcohol and other organic solvents at different temperature were measured.The results show that the water (aqueous 7 mmol/L of TTAB and 0.5 mol/L of n-propanol solution)/oil (0.5 mmol/L of picric acid in chloroform solution)/water (aqueous glucose solution) system performed sustained and stable oscillation at 30℃.And the novel system can recognise added amino acid.

  20. Anastomose carótido-basilar

    Directory of Open Access Journals (Sweden)

    Ricardo Reixach-Granés

    1965-09-01

    Full Text Available O autor relata um caso de anastomose carótido-basilar por persistência da artéria trigeminal, demonstrado angiogràficamente. O paciente apresentou hemiplegia súbita e era portador de transtornos mentais de tipo deficitário. A pneumencefalografia evidenciou atrofia do parênquima cerebral do lado da anomalia.

  1. Mechanical thrombectomy in basilar artery thrombosis

    DEFF Research Database (Denmark)

    Fesl, Gunther; Holtmannspoetter, Markus; Patzig, Maximilian;

    2014-01-01

    PURPOSE: Multiple endovascular devices have been used for mechanical thrombectomy (MT) in basilar artery occlusion (BAO) for >10 years. Based on a single-center experience during the course of one decade, we present data on safety and efficacy of previous MT devices compared with modern stent ret...

  2. Basilar artery migraine and reversible imaging abnormalities.

    Science.gov (United States)

    Maytal, J; Libman, R B; Lustrin, E S

    1998-01-01

    We report a case of a basilar artery migraine in a 17-year-old boy with transient CT and MR abnormalities after each of two migraine episodes. A repeat MR study 6 months after the last event showed complete resolution of the lesion. Transient abnormalities on brain images similar to those shown in our case have been reported in patients with migraine and other neurologic conditions and are most likely related to cerebral vasogenic edema.

  3. Endovascular treatment for ruptured basilar apex aneurysm

    Directory of Open Access Journals (Sweden)

    Sheng LI

    2011-12-01

    Full Text Available Objective The present study aims to prove the effectiveness and safety of endovascular interventional therapy for ruptured basilar apex aneurysm.Methods The imaging data,methods of endovascular treatment,and clinical results of 12 patients suffering from ruptured basilar apex aneurysms from January 2001 to December 2009 were retrospectively analyzed.The 12 patients were composed of 5 males and 7 females,and their ages ranged from 21 years to 58 years.Results Nine patients suffered from narrow-necked aneurysms,which were directly embolized,and the other three suffered from wide-necked aneurysms,which were embolized using a microstent.Eight aneurysms were completely embolized,and the other four were partly embolized.No rebleeding occurred within the follow-up period of 12 months to 36 months,and all patients recovered well without neurological defects.Conclusions Therefore,endovascular treatment for ruptured basilar apex aneurysm is a semi-invasive,safe,and effective method.

  4. Neurofibromatosis, stroke and basilar impression: case report

    Directory of Open Access Journals (Sweden)

    PIOVESAN ELCIO JULIATO

    1999-01-01

    Full Text Available Neurofibromatosis type 1 (NF1 can virtually affect any organ, presenting most frequently with "cafe au lait" spots and neurofibromas. Vasculopathy is a known complication of NF1, but cerebrovascular disease is rare. We report the case of a 51-year-old man admitted to the hospital with a history of stroke four months before admission. On physical examination, he presented various "cafe au lait" spots and cutaneous neurofibromas. Neurologic examination demonstrated right-sided facial paralysis, right-sided hemiplegia, and aphasia. Computed tomography scan of head showed hypodense areas in the basal ganglia and centrum semiovale. Radiographs of cranium and cervical spine showed basilar impression. Angiography revealed complete occlusion of both vertebral and left internal carotid arteries, and partial stenosis of the right internal carotid artery. A large network of collateral vessels was present (moyamoya syndrome. It is an uncommon case of occlusive cerebrovascular disease associated with NF1, since most cases described in the literature are in young people, and tend to spare the posterior cerebral circulation. Basilar impression associated with this case may be considered a pure coincidence, but rare cases of basilar impression and NF1 have been described.

  5. Hipnoticos corticales y basilares y acciones anticonvulsivantes

    Directory of Open Access Journals (Sweden)

    Carlos Gutiérrez-Noriega

    1943-06-01

    Full Text Available Se estudian las diferencias de los hipnóticos corticales y basilares desde el punto de vista de sus acciones anticonvulsivantes. Los resultados son los siguientes: 1. Los hipnóticos del grupo basilar (barbitúrico y uretano poseen un poder anticonvulsivante considerablemente mayor que los hipnóticos del grupo cortical (alcoholes, aldehidos, bromuros, éter, con excepción del sulfato de magnesia, clasificado en el grupo subcortical, que tiene muy poca acción anticonvulsivante. 2. Algunos hipnóticos del grupo cortical (cloralosa disminuyen notablemente a dosis narcótica el umbral para las convulsiones clónicas, producidas por el cardiazol, coramina y estricnina; pero aumentan el umbral para las convulsiones tónicas. Estos hipnóticos actúan paradójicamente, como anticonvulsivantes y como sinergistas de los convulsivantes. 3. El sinergismo de cardiazol y estricnina para producir convulsiones clónicas es mucho más notable durante la narcosis por cloralosa que en el animal no anestesiado. 4. Existen significativas diferencias cualitativas y cuantitativas entre las convulsiones del animal no anestesiado y las convulsiones del animal durante la narcosis por cloralosa. En este último caso no se produce la reacción tónica, las reacciones neurovegetativas son más débiles, pero la duración de las convulsiones clónicas es considerablemente mayer. 5. Las diferencias de actividad anticonvulsivante observadas entre los dos grupos de hipnóticos, no pueden ser tomadas como prueba de la clasificación topográfica (córtico-basilar. Al contrario, sugieren que algunos hipnóticos del grupo cortical deben su típica manera de actuar a una acción estimulante tanto sobre la corteza cerebral como sobre los centros subcorticales. Se discute la posibilidad de que el sistema internuncial sea el que principalmente se estimula. Así, mientras que en la narcosis de tipo barbitúrico disminuye la excitabilidad de todo el sistema nervioso de relaci

  6. Basilar artery of the capybara (Hydrochaeris hydrochaeris): an ultrastructural study.

    Science.gov (United States)

    Islam, S; Ribeiro, A A C M; Loesch, A

    2004-04-01

    The present study investigated the ultrastructural features of the basilar artery of the largest rodent species, the capybara. The study suggests that the general ultrastructural morphological organization of the basilar artery of the capybara is similar to that of small rodents. However, there are some exceptions. The basilar artery of the capybara contains a subpopulation of 'granular' vascular smooth muscle cells resembling monocytes and/or macrophages. The possibility cannot be excluded that the presence of these cells reflects the remodelling processes of the artery due to animal maturation and the regression of the internal carotid artery. To clarify this issue, more systemic studies are required involving capybaras of various ages.

  7. Trigeminal neuralgia secondary to basilar impression: A case report

    Science.gov (United States)

    de Almeida Holanda, Maurus Marques; Pereira Neto, Normando Guedes; de Moura Peixoto, Gustavo; Pinheiro Santos, Rayan Haquim

    2015-01-01

    We report a rare case of trigeminal neuralgia. A 23-year-old woman with a history of 1 year of typical trigeminal neuralgia manifested the characteristics of basilar impression. Magnetic resonance imaging (MRI) demonstrated basilar impression, deformity of the posterior fossa with asymmetry of petrous bone, and compression of medulla oblongata in the topography of the odontoid apophysis. The operation was performed through a suboccipital craniectomy. The neuralgia disappeared after surgery and remains completely resolved until today. This is the second reported case of trigeminal neuralgia in a patient with basilar impression in Brazil. PMID:25972713

  8. Membrane-bound MinDE complex acts as a toggle switch that drives Min oscillation coupled to cytoplasmic depletion of MinD.

    Science.gov (United States)

    Vecchiarelli, Anthony G; Li, Min; Mizuuchi, Michiyo; Hwang, Ling Chin; Seol, Yeonee; Neuman, Keir C; Mizuuchi, Kiyoshi

    2016-03-15

    The Escherichia coli Min system self-organizes into a cell-pole to cell-pole oscillator on the membrane to prevent divisions at the cell poles. Reconstituting the Min system on a lipid bilayer has contributed to elucidating the oscillatory mechanism. However, previous in vitro patterns were attained with protein densities on the bilayer far in excess of those in vivo and failed to recapitulate the standing wave oscillations observed in vivo. Here we studied Min protein patterning at limiting MinD concentrations reflecting the in vivo conditions. We identified "burst" patterns--radially expanding and imploding binding zones of MinD, accompanied by a peripheral ring of MinE. Bursts share several features with the in vivo dynamics of the Min system including standing wave oscillations. Our data support a patterning mechanism whereby the MinD-to-MinE ratio on the membrane acts as a toggle switch: recruiting and stabilizing MinD on the membrane when the ratio is high and releasing MinD from the membrane when the ratio is low. Coupling this toggle switch behavior with MinD depletion from the cytoplasm drives a self-organized standing wave oscillator.

  9. Effect of acupuncture at Yifeng, Ermen and Zhongzhu acupoints on pathohistological and morphological changes of basilar membrane in guinea pigs with drug poisoning auditory injury%针刺翳风、耳门、中渚穴对药物中毒性听力损害豚鼠耳蜗基底膜病理组织形态的影响

    Institute of Scientific and Technical Information of China (English)

    付平; 郭长青; 耿恩广

    2006-01-01

    BACKGROUND: At present, there is no ideal way to treat auditory injury, and acupuncture would become an effective method to prevent and cure drug auditory injury.OBJECTIVE: To observe the effect of acupuncture at Yifeng, Ermen and Zhongzhu acupoints on improving histopathologic form of basilar membrane of guinea pig with drug poisoning auditory injury.DESIGN: Completely randomized design on the basis of experiment al animals.SETTING: Department of Neurology, Xuanwu Hospital, Capital University of Medical Sciences.MATERIALS: A total of 45 white male guinea pigs with normal Preyer's reflex were selected in this study. Guinea pigs were 3-4 months old, of general grade and weighted from 250 g to 300 g. All guinea pigs were randomly divided into 5 groups: normal group, model group, Yifeng group, Ermen group and Zhongzhu group with 9 in each group.METHODS: The experiment was completed at the Laboratory of College of Acupuncture and Moxibustion Affiliated to Beijing University of Traditional Chinese Medicine from April to July 2002. ① Normal group: Guinea pigs were fed with normal feed. Other four groups: Guinea pigs were injected into muscle with 80 mg/kg gentamycin for 20 days, and guinea pigs in Yifeng group, Ermen group and Zhongzhu group were acupunctured at corresponding acupoints at the same time. Before acupuncture, guinea pigs were fixed and rapidly acupunctured into subcutaneous tissue with stainless steel needle sized 0.35 mm × 25 mm. The needle was inserted about 10 mm. According to uniform reinforcing-reducing method, the needle was thrusted once every 10 minutes with each for 30 seconds and retained for 30 minutes. The course was 20 days. ② Basilar membrane of guinea pigs was established. Amount of hair cell was calculated under optic microscope (×200) to record deletion amount of hair cell and observe activity of succinic dehydrogenase; meanwhile, ultrastructure of hair cells was observed with transmission electron microscope (×5 000). Measurement

  10. Delayed onset of fatal basilar thrombotic embolus after whiplash injury

    DEFF Research Database (Denmark)

    Viktrup, L; Knudsen, G M; Hansen, S H

    1995-01-01

    BACKGROUND: Whiplash injuries are generally seen after rear-end rather than frontal car collisions. Previous reports have documented death up to 8 days after serious whiplash injury. We report a case of lethal basilar thrombotic embolus that occurred 2 months after the patient's injury...... in a collision. CASE DESCRIPTION: After whiplash trauma in a car accident, a 50-year-old taxi driver suffered from headache and episodic visual disturbances. Two months after the accident he suddenly lost consciousness and was admitted to the hospital. A CT scan performed at that time was indicative of basilar...... thrombosis. The patient died 3 days later. The autopsy revealed a thrombosis in the right vertebral artery and a thrombotic embolus in the basilar artery. Microscopically, a lesion of the right vertebral artery was found at the level of the atlantoaxial joint. CONCLUSIONS: We conclude that the whiplash...

  11. Microscopic anatomy of the human vertebro-basilar system

    Directory of Open Access Journals (Sweden)

    Renato P. Chopard

    1991-12-01

    Full Text Available Concerning the structure of connective-muscular components the authors studied the walls of the terminal segments of the vertebral arteries as well as the basilar artery, utilizing the following staining methods: Azan modified by Heideinheim, Weigert's resorcin-fuchsin, and Weigert modified by van Gieson. It was established that wall of the vertebro-basilar system exhibits a mixed structure, muscular and elastic, by means of which the vessels are adjusted to the specific blood circulation conditions. Thus, vertebral arteries show in the most external layer of tunica media an evident external elastic lamina. In contrast, in the basilar artery the elastic tissue is localized mainly in the tunica media, and is distributed heterogeneously. In its caudal segment the elastic fibers are situated in the most internal layer of tunica media, and in the cranial segment the elastic component is homogenously distributed in the whole of tunica media.

  12. Primary stenting as emergency therapy in acute basilar artery occlusion

    Energy Technology Data Exchange (ETDEWEB)

    Spreer, Joachim; Arnold, Sebastian; Klisch, Joachim; Schumacher, Martin [Section of Neuroradiology, University Hospital Freiburg, Breisacher Strasse 64, 79106 Freiburg (Germany); Els, Thomas; Hetzel, Andreas; Huppertz, Hans-Juergen; Oehm, Eckhardt [Department of Neurology, University Hospital Freiburg, Freiburg (Germany)

    2002-09-01

    In three patients with acute occlusion of the basilar artery intra-arterial fibrinolysis resulted in only partial recanalization and revealed severe stenosis as the underlying cause. Application of micro-stents without previous dilatation resulted in vessel re-opening. Two patients had an excellent clinical outcome. One patient died 10 days after the stroke due to brainstem infarction. Emergency primary stent application may improve the outcome in acute basilar artery occlusion, if intra-arterial thrombolysis fails to re-establish a sufficient flow. (orig.)

  13. Basilar artery aneurysm case presented with neck pain

    Directory of Open Access Journals (Sweden)

    Uygar Utku

    2013-04-01

    Full Text Available Neck pain related with disorders of the brain and neck vascular structures is not rare but importance was attached to a condition that is often overlooked. Tension as a sudden onset, radiating to the nape, the neck pain becomes unbearable and within seconds the raging 51-year-old female patient with aneurysm at the distal end of basilar artery was found. Case, the only sign of neck pain with unruptured basilar artery aneurysm is presented in terms of raising awareness on the subject.

  14. Middle meningeal artery arising from the basilar artery.

    Science.gov (United States)

    Salem, Mohamed M; Fusco, Matthew R; Dolati, Parviz; Reddy, Arra S; Gross, Bradley A; Ogilvy, Christopher S; Thomas, Ajith J

    2014-12-01

    Various anomalies for the origin of the middle meningeal artery (MMA) have been described in the literature. However, origin of the MMA from the basilar trunk is an extremely rare variant. We report on a 54-year-old female who presented with frequent headaches; magnetic resonance imaging showed a right parietal meningioma. The abnormal origin of the middle meningeal artery from the basilar artery was diagnosed by angiography performed for preoperative embolization of the tumor. We report on the case with a review of the embryologic basis, possible explanations for this aberrant origin, and its clinical implications.

  15. Linking Cellular Mechanisms to Behavior: Entorhinal Persistent Spiking and Membrane Potential Oscillations May Underlie Path Integration, Grid Cell Firing, and Episodic Memory

    Directory of Open Access Journals (Sweden)

    Michael E. Hasselmo

    2008-01-01

    Full Text Available The entorhinal cortex plays an important role in spatial memory and episodic memory functions. These functions may result from cellular mechanisms for integration of the afferent input to entorhinal cortex. This article reviews physiological data on persistent spiking and membrane potential oscillations in entorhinal cortex then presents models showing how both these cellular mechanisms could contribute to properties observed during unit recording, including grid cell firing, and how they could underlie behavioural functions including path integration. The interaction of oscillations and persistent firing could contribute to encoding and retrieval of trajectories through space and time as a mechanism relevant to episodic memory.

  16. Alterations of voltage-dependent calcium channel currents in basilar artery smooth muscle cells at early stage of subarachnoid hemorrhage in a rabbit model.

    Directory of Open Access Journals (Sweden)

    Xianqing Shi

    Full Text Available OBJECTIVE: To investigate the changes in the currents of voltage-dependent calcium channels (VDCCs in smooth muscle cells of basilar artery in a rabbit model of subarachnoid hemorrhage (SAH. METHODS: New Zealand white rabbits were randomly divided into five groups: sham (C, normal (N, 24 hours (S1, 48 hours (S2 and 72 hours (S3 after SAH. Non-heparinized autologous arterial blood (1 ml/kg was injected into the cisterna magna to create SAH after intravenous anesthesia, and 1 ml/kg of saline was injected into cisterna magna in the sham group. Rabbits in group N received no injections. Basilar artery in S1, S2, S3 group were isolated at 24, 48, 72 hours after SAH. Basilar artery in group C was isolated at 72 hours after physiological saline injection. Basilar artery smooth muscle cells were isolated for all groups. Whole-cell patch-clamp technique was utilized to record cell membrane capacitance and VDCCs currents. The VDCCs antagonist nifedipine was added to the bath solution to block the Ca(++ channels currents. RESULTS: There were no significant differences in the number of cells isolated, the cell size and membrane capacitance among all the five groups. VDCC currents in the S1-S3 groups had higher amplitudes than those in control and sham groups. The significant change of current amplitude was observed at 72 hours after SAH, which was higher than those of 24 and 48 hours. The VDCCs were shown to expression in human artery smooth muscle cells. CONCLUSIONS: The changes of activation characteristics and voltage-current relationship at 72 hours after SAH might be an important event which leads to a series of molecular events in the microenvironment of the basilar artery smooth muscle cells. This may be the key time point for potential therapeutic intervention against subarachnoid hemorrhage.

  17. Intraorbital ophthalmic artery aneurysm associated with basilar tip saccular aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Dehdashti, A.R.; Tribolet, N. de [Department of Neurosurgery, HUG, Geneva (Switzerland); Safran, A.B. [Department of Ophthalmology, HUG, Geneva (Switzerland); Martin, J.B.; Ruefenacht, D.A. [Division of Neuroradiology, HUG, Geneva (Switzerland)

    2002-07-01

    We present a rare case of intraorbital ophthalmic artery aneurysm found incidentally, together with a ruptured aneurysm of the tip of the basilar artery. The intraorbital aneurysm was asymptomatic, and no treatment was offered. Angiographic control was recommended to detect any progression. Treatment may be indicated for documented enlargement or significant mass effect of the aneurysm. (orig.)

  18. Basilar artery thrombosis in the setting of antiphospholipid syndrome.

    Science.gov (United States)

    Saad, Amin F; Nickell, Larry T; Heithaus, R Evans; Shamim, Sadat A; Opatowsky, Michael J; Layton, Kennith F

    2014-07-01

    Antiphospholipid syndrome is an autoimmune disorder characterized by arterial or venous thrombosis, recurrent first-trimester pregnancy loss, and multiple additional clinical manifestations. We describe a man with severe atherosclerotic basilar artery stenosis and superimposed in situ thrombus who was found to have antiphospholipid syndrome.

  19. Relaxation effect of abacavir on rat basilar arteries.

    Directory of Open Access Journals (Sweden)

    Rachel Wai Sum Li

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

  20. Characterization of voltage-gated K+ currents contributing to subthreshold membrane potential oscillations in hippocampal CA1 interneurons.

    Science.gov (United States)

    Morin, France; Haufler, Darrell; Skinner, Frances K; Lacaille, Jean-Claude

    2010-06-01

    CA1 inhibitory interneurons at the stratum lacunosum-moleculare and radiatum junction (LM/RAD-INs) display subthreshold membrane potential oscillations (MPOs) involving voltage-dependent Na(+) and A-type K(+) currents. LM/RAD-INs also express other voltage-gated K(+) currents, although their properties and role in MPOs remain unclear. Here, we characterized these voltage-gated K(+) currents and investigated their role in MPOs. Using outside-out patch recordings from LM/RAD-IN somata, we distinguished four voltage-gated K(+) currents based on their pharmacology and activation/inactivation properties: a fast delayed rectifier current (I(Kfast)), a slow delayed rectifier current (I(Kslow)), a rapidly inactivating A-type current (I(A)), and a slowly inactivating current (I(D)). Their relative contribution to the total K(+) current was I(A) > I(Kfast) > I(Kslow) = I(D). The presence of I(D) and the relative contributions of K(+) currents in LM/RAD-INs are different from those of other CA1 interneurons, suggesting the presence of differential complement of K(+) currents in subgroups of interneurons. We next determined whether these K(+) currents were sufficient for MPO generation using a single-compartment model of LM/RAD-INs. The model captured the subthreshold voltage dependence of MPOs. Moreover, all K(+) currents were active at subthreshold potentials but I(D), I(A), and the persistent sodium current (I(NaP)) were most active near threshold. Using impedance analysis, we found that I(A) and I(NaP) contribute to MPO generation by modulating peak spectral frequency during MPOs and governing the voltage range over which MPOs occur. Our findings uncover a differential expression of a complement of K(+) channels that underlies intrinsic rhythmic activity in inhibitory interneurons.

  1. [Basilar ectasia and stroke: clinical aspects of 21 cases].

    Science.gov (United States)

    de Oliveira, R de M; Cardeal, J O; Lima, J G

    1997-09-01

    Ectasia of the basilar artery (EB) occurs when its diameter is greater than normal along all or part of its course, and/or when it is abnormally tortuous. EB may cause cranial nerve dysfunction, ischemic stroke or subarachnoid hemorrhage, pseudotumor or hydrocephalus. We tried to describe cases of stroke associated with EB, analyze its frequency, clinical aspects, and the mechanisms involved in different forms of its presentation. We found 21 patients with stroke and EB. The association between EB and stroke was more prevalent in males over the age of fifty. Main symptoms were hemiparesia, cranial nerves dysfunction, and cerebellar ataxia. Cerebral infarcts associated with EB were due to different mechanisms: arterial thrombosis, artery-to-artery embolism, mass effect with angulation and obstruction of the vertebral and basilar branches.

  2. Membraner

    DEFF Research Database (Denmark)

    Bach, Finn

    2009-01-01

    Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner......Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner...

  3. A cadaveric study of the endoscopic endonasal transclival approach to the basilar artery.

    Science.gov (United States)

    Lai, Leon T; Morgan, Michael K; Chin, David C W; Snidvongs, Kornkiat; Huang, June X Z; Malek, Joanne; Lam, Matthew; McLachlan, Rohan; Harvey, Richard J

    2013-04-01

    The anterior transclival route to basilar artery aneurysms is not widely performed. The objective of this study was to carry out a feasibility assessment of the transclival approach to basilar aneurysms with advanced endonasal techniques on 11 cadaver heads. Clival dura was exposed from the sella to the foramen magnum between the paraclival segments of the internal carotid arteries (ICA) laterally. An inverted dural "U" flap was reflected inferiorly to expose the basilar artery. The maximal dimensions from operative measurements were recorded. Surgical manoeuvrability of multiple instruments and the proficiency to place proximal and distal vascular clips were evaluated. The mean operative depth (± standard deviation), measured from the anterior choanae to the basilar artery, was 110±6mm. The lateral corridors were limited distally by the medial pterygoids (mean width 21±2mm) and paraclival ICA (mean width 20±2mm). The mean transclival craniectomy dimensions were 19±2mm (width) and 23±4mm (height). Exposure of the basilar-anterior inferior cerebellar artery junction, superior cerebellar artery, and the basilar caput were possible in 100%, 91%, and 64% of instances, respectively. Placements of proximal and distal aneurysm clips were achieved in all instances. Based on our findings, the transclival endoscopic endonasal surgery approach provides excellent visualisation of the basilar artery. Clip application and manoeuvrability of instruments was considered adequate for basilar aneurysm surgery. Surgical skills and instrumentation to control significant haemorrhage can potentially limit the clinical applicability of this technique.

  4. Vertebral artery stenosis in the Basilar Artery International Cooperation Study (BASICS): prevalence and outcome

    NARCIS (Netherlands)

    Compter, A.; Hoeven, E.J. van der; Worp, H.B. van der; Vos, J.A.; Weimar, C.; Rueckert, C.M.; Kappelle, L.J.; Algra, A.; Schonewille, W.J.; Leeuw, F.E. de

    2015-01-01

    We assessed the prevalence of vertebral artery (VA) stenosis or occlusion and its influence on outcome in patients with acute basilar artery occlusion (BAO). We studied 141 patients with acute BAO enrolled in the Basilar Artery International Cooperation Study (BASICS) registry of whom baseline CT an

  5. Vertebral artery stenosis in the Basilar Artery International Cooperation Study (BASICS) : prevalence and outcome

    NARCIS (Netherlands)

    Compter, Annette; van der Hoeven, Erik J R J; van der Worp, H. Bart; Vos, Jan Albert; Weimar, Christian; Rueckert, Christina M.; Kappelle, L. Jaap; Algra, Ale; Schonewille, Wouter J.; Vergouwen, MD

    2015-01-01

    We assessed the prevalence of vertebral artery (VA) stenosis or occlusion and its influence on outcome in patients with acute basilar artery occlusion (BAO). We studied 141 patients with acute BAO enrolled in the Basilar Artery International Cooperation Study (BASICS) registry of whom baseline CT an

  6. Hemifacial spasm in a patient with basilar artery dolichoectasia caused by uncontrolled hypertension

    Directory of Open Access Journals (Sweden)

    Gordon S. Crabtree

    2016-10-01

    Full Text Available A 47-year-old male presented with a 2-year history of hemifacial spasm. Magnetic resonance imaging performed showed his tortuous basilar artery with nerve compression, and the patient was treated conservatively with botulinum toxin injections with complete resolution of symptoms. This rare disease was caused by his long history of hypertension, which led to his major basilar artery dolichoectasia.

  7. Basilar artery occlusion: Prognostic signs of severity on computed tomography

    Energy Technology Data Exchange (ETDEWEB)

    Poletti, Pierre-Alexandre, E-mail: pierre-alexandre.poletti@hcuge.ch [Service of Radiology, University Hospital of Geneva (Switzerland); Pereira, Vitor Mendes [Service of Neuroradiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Department of Medical Imaging, University of Toronto (Canada); Department of Surgery, University of Toronto (Canada); Lovblad, Karl-Olof [Service of Neuroradiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Canel, Lucie [Service of Radiology, University Hospital of Geneva (Switzerland); Sztajzel, Roman [Service of Neurology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Becker, Minerva [Service of Radiology, University Hospital of Geneva (Switzerland); Perneger, Thomas [Division of Clinical Epidemiology, University Hospital of Geneva, 4 rue Gabrielle-Perret-Gentil, 1211 Geneva (Switzerland); Platon, Alexandra [Service of Radiology, University Hospital of Geneva (Switzerland)

    2015-07-15

    Highlights: • The main CT signs associated with basilar artery occlusion were analyzed. • CT sign of acute ischemic lesion is significantly associated with a bad outcome. • The site of the basilar artery occlusion is not associated to the patients’ outcome. - Abstract: Purpose: To determine the computed tomography (CT) signs that are predictive of the clinical outcome of basilar artery occlusion (BAO). Materials and methods: The study population consisted in 37 patients (14 women, 23 men, mean age: 63 years), admitted with onset of neurological deficit, starting 1–72 h prior to admission, who were diagnosed with BAO on the basis of a CT examination with intravenous contrast agent. The following signs were collected on CT scans performed on admission: clot density on noncontrast images, clot length, and clot location, as well as the presence of acute ischemic lesions. The results were compared against the modified Rankin Scale (mRS) score of patients at 3 months, favorable clinical outcome being defined as a mRS score ≤3. Results: The clinical outcome was favorable in 13 (35%) of the 37 patients and unfavorable in 24 (65%). Signs of acute ischemia were visible in 13 of the 24 patients with unfavorable outcome but in none of the 13 patients with favorable outcome (p < 0.001). None of the other CT signs analyzed were significantly correlated with clinical prognosis. Conclusion: Of all the CT signs analyzed, only the presence of signs of acute ischemia on the admission CT of patients with BAO was associated with poor prognosis.

  8. Surgical treatment of Chiari malformation complicated with basilar impression

    Directory of Open Access Journals (Sweden)

    Yuan MA

    2011-02-01

    Full Text Available Objective To evaluate the therapeutic effect of small craniotomic posterior fossa decompression combined with occipital-cervical bone graft fusion and internal fixation on Chiari malformation complicated with basilar impression.Methods The clinical data of 16 cases(7 males and 9 females,aged 17 to 65 years,mean 36.4 of Chiari malformation complicated with basilar impression from 2006 to 2010 were retrospectively analyzed.The diagnoses for all the patients were confirmed by radiology.Small craniotomic posterior fossa decompression was performed in all patients,cerebellar tonsils were resected,and then one-stage occipital-cervical bone graft fusion using autogenous iliac bone and internal wiring fixation were performed.Neck support was used for 3 months after surgery.Results Symptoms were significantly improved in all cases after surgical operation.No patient died or infected.Cerebrospinal fluid leakage was found at draining site in one case.Transient pain of scapular and chest was found in one case and disappeared spontaneously.A 6-months follow-up showed that 6 patients were cured,9 improved and 1 unchanged according to Symon and Lavender standard.Postoperative MRI showed the reconstructed cisterna magna was clear in all patients,no cerebellar ptosis was found,and the occipital-cervical graft bone was fused.Conclusion In patients with Chiari malformation complicated with basilar impression,small craniotomic posterior fossa decompression combined with one-stage occipital-cervical bone graft fusion and internal wiring fixation has a clear and definite effect,it can increase the volume of posterior fossa and alleviate the ventral brain stem compression simultaneously,and reconstruct the stability of cranio-cervical junction.

  9. Segmental myoclonus and basilar artery giant aneurysm case report

    Directory of Open Access Journals (Sweden)

    J. Pitágoras de Mattos

    1992-12-01

    Full Text Available A 70 years-old man was admitted at our hospital because of unstable angina pectoris. He had essential hypertension and right hemiplegia from a ischemic stroke two years before admission. On neurologic examination, it was found mental disorientation, unstable emotionality, right spastic hemiparesis with right Babinski sign, and segmental myoclonus affecting the superior lip and the palate (palatal nystagmus on the right side. On the CT scan, a giant aneurysm of the basilar artery was detected. We conclude that the segmental myoclonus could be explained by ischemic lesions in the Guillain - Mollaret triangle.

  10. Stent-based mechanical thrombectomy in acute basilar artery occlusion.

    Science.gov (United States)

    Cohen, José E; Leker, Ronen R; Moscovici, Samuel; Attia, Moshe; Itshayek, Eyal

    2011-12-01

    Stent-based mechanical thrombectomy was recently proposed as an effective alternative to other mechanical techniques to achieve recanalization of large-vessel embolic occlusions in the anterior circulation. To our knowledge, there are no reports of the use of this technique in acute basilar artery occlusion (ABAO). We present a patient with complete endovascular recanalization of ABAO using a stent-based thrombectomy technique. Advantages and limitations of this technique in the management of ABAO are discussed. The stent-thrombectomy technique is promising, and will need further evaluation in posterior circulation stroke.

  11. Bilateral hypoplasia of the internal carotid arteries with basilar aneurysm

    Energy Technology Data Exchange (ETDEWEB)

    Briganti, F.; Tortora, F.; Elefante, A. [Universita di Napoli Federico II, Dipartimento di Scienze Neurologiche, Cattedra di Neuroradiologia, 80131, Napoli (Italy); Maiuri, F. [Universita di Napoli Federico II, Department of Neurological Sciences, Neurosurgery Service, Napoli (Italy)

    2004-10-01

    We report a rare case of bilateral hypoplasia of the internal carotid arteries with an associated aneurysm of the basilar tip, studied by CT angiography, MR angiography and digital angiography. The patient became symptomatic with an episode of loss of consciousness, likely due to reduced blood perfusion. The other 20 reported cases of bilateral carotid hypoplasia (only four of which with an associated aneurysm) are reviewed. The findings of noninvasive procedures (including narrowing of the carotid canals on CT) may lead to a correct diagnosis before angiography is performed; they may also help to differentiate angiographic narrowing of the hypoplastic internal carotids from the string sign often observed in some acquired conditions. (orig.)

  12. Spike-timing precision and neuronal synchrony are enhanced by an interaction between synaptic inhibition and membrane oscillations in the amygdala.

    Directory of Open Access Journals (Sweden)

    Steven J Ryan

    Full Text Available The basolateral complex of the amygdala (BLA is a critical component of the neural circuit regulating fear learning. During fear learning and recall, the amygdala and other brain regions, including the hippocampus and prefrontal cortex, exhibit phase-locked oscillations in the high delta/low theta frequency band (∼2-6 Hz that have been shown to contribute to the learning process. Network oscillations are commonly generated by inhibitory synaptic input that coordinates action potentials in groups of neurons. In the rat BLA, principal neurons spontaneously receive synchronized, inhibitory input in the form of compound, rhythmic, inhibitory postsynaptic potentials (IPSPs, likely originating from burst-firing parvalbumin interneurons. Here we investigated the role of compound IPSPs in the rat and rhesus macaque BLA in regulating action potential synchrony and spike-timing precision. Furthermore, because principal neurons exhibit intrinsic oscillatory properties and resonance between 4 and 5 Hz, in the same frequency band observed during fear, we investigated whether compound IPSPs and intrinsic oscillations interact to promote rhythmic activity in the BLA at this frequency. Using whole-cell patch clamp in brain slices, we demonstrate that compound IPSPs, which occur spontaneously and are synchronized across principal neurons in both the rat and primate BLA, significantly improve spike-timing precision in BLA principal neurons for a window of ∼300 ms following each IPSP. We also show that compound IPSPs coordinate the firing of pairs of BLA principal neurons, and significantly improve spike synchrony for a window of ∼130 ms. Compound IPSPs enhance a 5 Hz calcium-dependent membrane potential oscillation (MPO in these neurons, likely contributing to the improvement in spike-timing precision and synchronization of spiking. Activation of the cAMP-PKA signaling cascade enhanced the MPO, and inhibition of this cascade blocked the MPO. We discuss

  13. The influence of oscillating electromagnetic fields on membrane structure and function: Synthetic liposome and natural membrane bilayer systems with direct application to the controlled delivery of chemical agents

    Energy Technology Data Exchange (ETDEWEB)

    Liburdy, R.P.; de Manincor, D.; Fingado, B.

    1989-09-01

    Investigations have been conducted to determine if an imposed electromagnetic field can influence membrane transport, and ion and drug permeability in both synthetic and natural cell membrane systems. Microwave fields enhance accumulation of sodium in the lymphocyte and induce protein shedding at Tc. Microwaves also trigger membrane permeability of liposome systems under specific field exposure conditions. Sensitivity varies in a defined way in bilayers displaying a membrane structural phase transition temperature, Tc; maximal release was observed at or near Tc. Significantly, liposome systems without a membrane phase transition were also found to experience permeability increases but, in contrast, this response was temperature independent. The above results indicate that field-enhanced drug release occurs in liposome vesicles that possess a Tc as well as non-Tc liposomes. Additional studies extend non-Tc liposome responses to the in vivo case in which microwaves trigger Gentamicin release from a liposome depot'' placed subcutaneously in the rat hind leg. In addition, evidence is provided that cell surface sequestered liposomes can be triggered by microwave fields to release drugs directly into target cells. 24 refs., 6 figs.

  14. CNS fungal meningitis to the "Top of the basilar"

    Institute of Scientific and Technical Information of China (English)

    Logan CS; Kirschner RC; Simonds GR

    2013-01-01

    Central nervous system(CNS) infections are a rare complication of epidural steroid injections and without strong clinical suspicion, fungal organisms may be overlooked among the long differential of causes of meningitis.Rare sequela of fungal meningitis is the development of stroke.To our knowledge, we present the first case of post epidural steroid injection(ESI) fungal meningitis leading toa basilar artery stroke, otherwise known as“top of the basilar” syndrome.We present a49-year-old female with a history ofESIs who presented to the emergency department with headache, neck stiffness, and abdominal pain.She was discharged after her labs and symptoms were deemed inconsistent with meningitis.She was eventually admitted and twelve days after her originalED visit, she was diagnosed with meningitis and started on anti-fungal treatment.She was discharged88 days later but was readmitted due to left sided weakness and mental status changes.She quickly lost motor and bulbar functions.AnMRA showed diminished distal flow through the basilar artery, suggesting near complete occlusion.Although appropriate long term anti-fungal treatment was started, the patient still succumbed to a rare vascular event.Physicians who are treating patients forESI meningitis should be aware of the potential for vasculitic and encephalitic complications.

  15. Local lysis in acute basilar artery occlusions: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Karnik, R.; Perneczky, G.; Ammerer, H.P.; Brenner, H.; Slany, J. (Krankenanstalt der Stadt Wien Rudolfstiftung (Austria))

    1984-01-01

    Thrombosis of the basilar artery is not a rare disease, and the mortality is reported to be 60 to 80%. Present standard therapy with heparin infusions yields poor results. The high risk of intracerebral haemorrhage prohibits systemic fibrinolytic therapy. Due to these facts and good experience in our department with the use of local intracoronary lysis in acute myocardial infarction, the method of local thrombolysis was applied in a case of acute basiliar artery thrombosis. Fibrinolytic therapy was started via an angiography catheter placed in the vertebral artery in a 28 year-old woman with hemiplegia and severe brain stem symptoms. The patient received 200,000 IU streptokinase within 2 hours and subsequently 300,000 IU urokinase within 10 hours. The vessel re-opened completely. The neurological symptoms decreased during the following weeks. Based on this experience and according to rare reports in the literature we believe local low-dose thrombolysis to be a causal therapy promising success for acute thrombosis of the basilar artery. This therapy can be carried out in every medical centre able to perform selective angiography and experienced in the administration of fibrinolytic drugs.

  16. Atherosclerotic Aneurysm of the Basilar Artery and Hydrocephalus. A Case Report

    Directory of Open Access Journals (Sweden)

    Ania Alvarado Borges

    2014-08-01

    Full Text Available Intracranial aneurysms are fairly common. Many of them produce no symptoms, often remaining undiagnosed during life. At autopsy, aneurysms of the basilar artery appear in 2 to 5% of the cases; among them, saccular and congenital aneurysms are more common than atherosclerotic and fusiform aneurysms. A case of atherosclerotic aneurysm of the basilar artery diagnosed at autopsy in an 88-year-old man is presented. This patient had been admitted with a diagnosis of ischemic stroke, intracranial hypertension and hydrocephalus, which led physicians to consider a posterior fossa tumor. This paper aims at presenting the autopsy findings that showed the presence of an atherosclerotic aneurysm of the basilar artery.

  17. Endovascular treatment of basilar tip aneurysms associated with moyamoya disease

    Energy Technology Data Exchange (ETDEWEB)

    Arita, K.; Kurisu, K.; Ohba, S.; Shibukawa, M.; Kiura, H.; Sakamoto, S. [Department of Neurosurgery, Graduate School of Biomedical Science, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, 734-8551, Hiroshima (Japan); Uozumi, T. [Hibino Hospital, Hiroshima (Japan); Nakahara, T. [Division of Neuroendovascular Treatment, Mazda Hospital, Hiroshima (Japan)

    2003-07-01

    We report the efficacy and safety of endovascular treatment of basilar tip aneurysms (BTA) in five patients with moyamoya disease. The patients underwent intra-aneurysmal embolisation with detachable platinum coils. Three BTA presented with subarachnoid haemorrhage (SAH); the other two were asymptomatic. In four cases, one embolisation procedure produced >95% angiographic obliteration of the aneurysm. In the other patient, 80-90% obliteration was achieved initially, but due to growth of the residual aneurysm, the procedure was repeated 7 months later. Two patients experienced transient oculomotor paresis as a procedure-related complication. Mean follow-up was 43.6{+-}34.0 months (range 8-92 months). One patient died of putaminal haemorrhage unrelated to the aneurysm 15 months after embolisation. The other four had no subsequent SAH and survived without sequelae. Endovascular embolisation using detachable platinum coils proved to be a safe and efficient treatment modality for BTA associated with moyamoya disease. (orig.)

  18. Post-Treatment Hemodynamics of a Basilar Aneurysm and Bifurcation

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, J; Hartman, J; Rodriguez, J; Maitland, D

    2008-01-16

    Aneurysm re-growth and rupture can sometimes unexpectedly occur following treatment procedures that were initially considered to be successful at the time of treatment and post-operative angiography. In some cases, this can be attributed to surgical clip slippage or endovascular coil compaction. However, there are other cases in which the treatment devices function properly. In these instances, the subsequent complications are due to other factors, perhaps one of which is the post-treatment hemodynamic stress. To investigate whether or not a treatment procedure can subject the parent artery to harmful hemodynamic stresses, computational fluid dynamics simulations are performed on a patient-specific basilar aneurysm and bifurcation before and after a virtual endovascular treatment. The simulations demonstrate that the treatment procedure produces a substantial increase in the wall shear stress. Analysis of the post-treatment flow field indicates that the increase in wall shear stress is due to the impingement of the basilar artery flow upon the aneurysm filling material and to the close proximity of a vortex tube to the artery wall. Calculation of the time-averaged wall shear stress shows that there is a region of the artery exposed to a level of wall shear stress that can cause severe damage to endothelial cells. The results of this study demonstrate that it is possible for a treatment procedure, which successfully excludes the aneurysm from the vascular system and leaves no aneurysm neck remnant, to elevate the hemodynamic stresses to levels that are injurious to the immediately adjacent vessel wall.

  19. Basilar impression and osteogenesis imperfecta in a three-year-old girl: CT and MRI

    Energy Technology Data Exchange (ETDEWEB)

    Rush, P.J.; Berbrayer, D.; Reilly, B.J.

    1989-01-01

    A 3-year-old girl with osteogenesis imperfecta developed symptomatic basilar impression. Her neurological symptoms were treated by foramen magnum decompression and laminectomy. This is an unusually young patient to have this condition.

  20. Electron in the field of flexural vibrations of a membrane: Quantum time, magnetic oscillations, and coherence breaking

    Science.gov (United States)

    Gornyi, I. V.; Dmitriev, A. P.; Mirlin, A. D.; Protopopov, I. V.

    2016-08-01

    We have studied the motion of an electron in a membrane under the influence of flexural vibrations with a correlator that decreases upon an increase in the distance in accordance with the law r-2η. We have conducted a detailed consideration of the case with η < 1/2, in which the perturbation theory is inapplicable, even for an arbitrarily weak interaction. It is shown that, in this case, reciprocal quantum time 1/τ q is proportional to g 1/(1-η) T (2-η)/(2-2η), where g is the electron-phonon interaction constant and T is the temperature. The method developed here is applied for calculating the electron density of states in a magnetic field perpendicular to the membrane. In particular, it is shown that the Landau levels in the regime with ω c τ q » 1 have a Gaussian shape with a width that depends on the magnetic field as B η. In addition, we calculate the time τφ of dephasing of the electron wave function that emerges due to the interaction with flexural phonons for η < 1/2. It has been shown that, in several temperature intervals, quantity 1/τφ can be expressed by various power functions of the electron-phonon interaction constant, temperature, and electron energy.

  1. On the possibility of molecular recognition of taste substances studied by Gábor analysis of oscillations

    DEFF Research Database (Denmark)

    Płocharska-Jankowska, E.; Szpakowska, M.; Mátéfi-Tempfli, Stefan

    2005-01-01

    A liquid membrane oscillator containing nitromethane as membrane material has been investigated. The influence of substances responsible for taste belonging to four classes (sweetness, saltiness, sourness and bitterness) on oscillation patterns of liquid membrane oscillators with cationic...

  2. The M-current contributes to high threshold membrane potential oscillations in a cell type-specific way in the pedunculopontine nucleus of mice

    Directory of Open Access Journals (Sweden)

    Csilla eBordas

    2015-04-01

    Full Text Available The pedunculopontine nucleus is known as a cholinergic nucleus of the reticular activating system, participating in regulation of sleep and wakefulness. Besides cholinergic neurons, it consists of GABAergic and glutamatergic neurons as well. According to classical and recent studies, more subgroups of neurons were defined. Groups based on the neurotransmitter released by a neuron are not homogenous, but can be further subdivided.The PPN neurons do not only provide cholinergic and non-cholinergic inputs to several subcortical brain areas but they are also targets of cholinergic and other different neuromodulatory actions. Although cholinergic neuromodulation has been already investigated in the nucleus, one of its characteristic targets, the M-type potassium current has not been described yet.Using slice electrophysiology, we provide evidence in the present work that cholinergic neurons possess M-current, whereas GABAergic neurons lack it. The M-current contributes to certain functional differences of cholinergic and GABAergic neurons, as spike frequency adaptation, action potential firing frequency or the amplitude difference of medium afterhyperpolarizations. Furthermore, we showed that high threshold membrane potential oscillation with high power, around 20 Hz frequency is a functional property of almost all cholinergic cells, whereas GABAergic neurons have only low amplitude oscillations. Blockade of the M-current abolished the oscillatory activity at 20 Hz, and largely diminished it at other frequencies.Taken together, the M-current seems to be characteristic for PPN cholinergic neurons. It provides a possibility for modulating gamma band activity of these cells, thus contributing to neuromodulatory regulation of the reticular activating system.

  3. The role of Na(+), K(+)-ATPase in the hypoxic vasoconstriction in isolated rat basilar artery.

    Science.gov (United States)

    Shen, Haitao; Liang, Peng; Qiu, Suhua; Zhang, Bo; Wang, Yongli; Lv, Ping

    2016-06-01

    Hypoxia-induced cerebrovascular dysfunction is a key factor in the occurrence and the development of cerebral ischemia. Na(+), K(+)-ATPase affects the regulation of intracellular Ca(2+) concentration and plays an important role in vascular smooth muscle function. However, the potential role of Na(+), K(+)-ATPase in hypoxia-induced cerebrovascular dysfunction is unknown. In this study, we found that the KCl-induced contraction under hypoxia in rat endothelium-intact basilar arteries is similar to that of denuded arteries, suggesting that hypoxia may cause smooth muscle cell (SMC)-dependent vasoconstriction in the basilar artery. The Na(+), K(+)-ATPase activity of the isolated basilar artery with or without endothelium significantly reduced with prolonged hypoxia. Blocking the Na(+)-Ca(2+) exchanger with Ni(2+) (10(-3)M) or the L-type Ca(2+) channel with nimodipine (10(-8)M) dramatically attenuated KCl-induced contraction under hypoxia. Furthermore, prolonged hypoxia significantly reduced Na(+), K(+)-ATPase activity and increased [Ca(2+)]i in cultured rat basilar artery SMCs. Hypoxia reduced the protein and mRNA expression of the α2 isoform of Na(+), K(+)-ATPase in SMCs in vitro. We used a low concentration of the Na(+), K(+)-ATPase inhibitor ouabain, which possesses a high affinity for the α2 isoform. The contractile response in the rat basilar artery under hypoxia was partly inhibited by ouabain pretreatment. The decreased Na(+), K(+)-ATPase activity in isolated basilar artery and the increased [Ca(2+)]i in SMCs induced by hypoxia were partly inhibited by pretreatment with a low concentration of ouabain. These results suggest that hypoxia may educe Na(+), K(+)-ATPase activity in SMCs through the α2 isoform contributing to vasoconstriction in the rat basilar artery.

  4. Entrainment in solution of an oscillating NADH oxidase activity from the bovine milk fat globule membrane with a temperature-compensated period length suggestive of an ultradian time-keeping (clock) function

    Science.gov (United States)

    Morre, D. James; Lawler, Juliana; Wang, Sui; Keenan, Thomas W.; Morre, Dorothy M.

    2002-01-01

    Entrainment in solution of an oscillating activity with a temperature compensated period of 24 min is described for a NADH oxidase (NOX) activity of the bovine milk fat globule membrane, a derivative of the mammary epithelial cell plasma membrane. The period of 24 min remained unchanged at 17 degrees C, 27 degrees C and 37 degrees C whereas the amplitude approximately doubled with each 10 degree C rise in temperature (Q(10)congruent with 2). The periodicity was observed with both intact milk fat globule membranes and with detergent-solubilized membranes, demonstrating that the oscillations did not require an association with membranes. The periodicity was not the result of instrument variation or of chemical interactions among reactants in solution. Preparations with different periodicities entrained (autosynchronized) when mixed. Upon mixing, the preparations exhibited two oscillatory patterns but eventually a single pattern representing the mean of the farthest separated maxima of the two preparations analyzed separately emerged. The cell surface NOX protein is the first reported example of an entrainable biochemical entity with a temperature-compensated periodicity potentially capable of functioning as an ultradian or circadian clock driver.

  5. Interdependence between oscillations and transients of delayed fluorescence induction processes in the thylakoid membrane of the intact maize leaf: Responses to effects of increased temperatures and drought

    Directory of Open Access Journals (Sweden)

    Radenović Čedomir N.

    2010-01-01

    Full Text Available Standard induction processes of delayed fluorescence (DF of chlorophyll (induction signals occur when an intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for more than 15 minutes (t > 15 min, and at the same time the leaf is illuminated with the intermittent white light. Resolved induction processes of DF chlorophyll into transients: A, B, C, D and E occur when the intact leaf segment of maize inbreds and hybrids is kept in the phosphoroscope darkroom for a significantly shorter period (500 s > t > 30 s, with the time rate t of 30 s, prior to its illumination with the intermittent white light. Induction transients: A, B, C, D and E are characterized with the time of their generation: tA = 31±6 ms (A, tB = 5 ± 0,5 s (B, tC = 15±5 s (C, tD = 360±20 s (D and tE = 670±35 s (E, dynamics of changes in transients intensities (IA, IB, IC, ID and IE and mechanisms of their generation. The induction processes of chlorophyll DF of the intact leaf of maize inbreds and hybrids resolved into transients: A, B, C, D and E are accompanied by the occurrence and different levels of activation energy (Ea, kJ mol-1 that correspond to critical temperatures ranging from 28 to 33°C. The generation mechanisms of induction transients A, B, C, D and E classify them into two groups. Transients A and B are of a physical character, while the transients: C, D, and E are of a chemical character. It is shown that the generation of the induction transients: B, C, D and E simultaneously follows establishing of the oscillations of induction processes of the DF chlorophyll. Oscillating of induction processes of DF chlorophyll is explained by the ion (K+, Na+, H+, Cl- transport mechanism across the thylakoid membrane of the intact leaf of maize inbreds and hybrids grown under conditions of air drought, increased temperatures and water deficiency in the medium.

  6. Basilar skull fracture in a Thoroughbred colt: Radiography or computed tomography?

    Directory of Open Access Journals (Sweden)

    Chee Kin Lim

    2013-04-01

    Full Text Available A two-year-old Thoroughbred colt was presented to the Equine Clinic, Onderstepoort Veterinary Academic Hospital for head trauma after rearing and falling backwards, hitting his head on the ground. Following medical therapy for acute onset neurological impairment secondary to a suspected basilar skull fracture, the horse was anaesthetised and computed tomography of the skull was performed. A diagnosis of a comminuted basilar skull fracture was made and skull radiographs were taken for comparison. The horse was subsequently euthanased owing to the poor prognosis; necropsy findings were compatible with imaging findings. The value and limitation of computed tomography versus radiography for the diagnosis of basilar skull fracture are discussed in this report. Introduction

  7. Basilar skull fracture in a Thoroughbred colt: Radiography or computed tomography?

    Directory of Open Access Journals (Sweden)

    Chee Kin Lim

    2013-02-01

    Full Text Available A two-year-old Thoroughbred colt was presented to the Equine Clinic, Onderstepoort Veterinary Academic Hospital for head trauma after rearing and falling backwards, hitting his head on the ground. Following medical therapy for acute onset neurological impairment secondary to a suspected basilar skull fracture, the horse was anaesthetised and computed tomography of the skull was performed. A diagnosis of a comminuted basilar skull fracture was made and skull radiographs were taken for comparison. The horse was subsequently euthanased owing to the poor prognosis; necropsy findings were compatible with imaging findings. The value and limitation of computed tomography versus radiography for the diagnosis of basilar skull fracture are discussed in this report.

  8. Rapid ventricular pacing for a basilar artery pseudoaneurysm in a pediatric patient: case report.

    Science.gov (United States)

    Nimjee, Shahid M; Smith, Tony P; Kanter, Ronald J; Ames, Warwick; Machovec, Kelly A; Grant, Gerald A; Zomorodi, Ali R

    2015-06-01

    Large cerebral aneurysms of the basilar apex are difficult to treat. Recently, endovascular treatment has mitigated much of the morbidity associated with treating these lesions. However, the morphology of aneurysms of the vertebrobasilar system can preclude endovascular treatment. Rapid ventricular pacing (RVP) facilitates open surgical treatment of cerebral aneurysms. It can assist in reducing the pressure of the neck of the aneurysm, allowing safe application of a clip. The authors present a case of a pediatric patient who developed a basilar artery pseudoaneurysm that required surgery. Given the large size of the aneurysm, RVP was performed, allowing the surgeons to dissect the dome of the aneurysm from the surrounding tissue and pontine perforating branches away from the lesion to safely clip the lesion. The patient had an uneventful recovery. To the authors' knowledge, this represents the first known case of RVP to aid in basilar artery clip occlusion in a pediatric patient.

  9. Characterization of CGRP(1) receptors in the guinea pig basilar artery

    DEFF Research Database (Denmark)

    Jansen-Olesen, I; Kaarill, L; Edvinsson, L

    2001-01-01

    The purpose of the present study was to characterise receptors mediating calcitonin gene-related peptide (CGRP)-induced relaxation of guinea pig basilar artery. This was done by investigating vasomotor responses in vitro and performing autoradiographic binding studies. We also intended to study...... the importance of an intact endothelium. Agonist studies showed that peptides of the CGRP family induced relaxation of the guinea pig basilar artery with the following order of potency: human beta-CGRP=human alpha-CGRP>adrenomedullin=[acetamidomethyl-Cys(2,7)]alpha-human CGRP ([Cys(ACM)(2,7)]CGRP...... in the absence of human CGRP-(8-37). The study shows the presence of a relaxant CGRP(1) receptor on the smooth muscle cells of guinea pig basilar artery. Various endothelial factors did not influence relaxant responses....

  10. 'Top of the basilar' syndrome: Clinico-radiological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, M.; Tanaka, S.; Kohama, A.

    1987-07-01

    Sixteen patients having infarction caused by circulatory disturbance at the top of the basilar artery, that is to say, the 'top of the basilar' syndrome, were studied, the diagnosis having been made by computerized tomography. Infarcts were widely distributed in each patient between the thalamus, midbrain, pons, cerebellum, and occipital lobe. Both thalami were involved in 7 cases. When the thalamus was involved bilaterally, the low density areas were symmetrical in size and localization. Angiography revealed that stenosis or occlusion by within a circle 2 cm in diameter surrounding the five-forked junction at the top of the basilar artery in 84.6%. Recanalization of the occluded artery occurred in 61.5%, suggesting that embolism played an important role in appearance of this syndrome.

  11. [Thrombolysis of the basilar artery: 5-year results from the Saarland stroke registry].

    Science.gov (United States)

    Grunwald, I Q; Struffert, T; Roth, C; Papanagiotou, P; Scheuermann, J; Voges, M; Reith, W

    2005-05-01

    Acute thrombosis of the basilar artery has a fatal outcome if left untreated. The relatively good prognosis with intra-arterial thrombolysis makes it the therapy of choice for acute basilar thrombosis. In the Saarland stroke registry, we analyzed 47 patients with angiographically proven basilar artery thrombosis within the last 5 years. We observed a better outcome in patients with good income, with recanalization, and a short time between onset of symptoms and start of thrombolysis. The complications, such as intracerebral bleedings, occurred only in the group treated with rt-PA. Intra-arterial thrombolysis with urokinase or rt-PA is a relatively safe therapy, but should be performed in neuroradiological centers. With progressing symptoms the therapeutic window can be stretched up to 12 h, but coma lasting for more than 4 h is related to a bad outcome.

  12. Technical nuances of subtemporal approach for the treatment of basilar tip aneurysm

    Science.gov (United States)

    Nakov, Vladimir S.; Spiriev, Toma Y.; Todorov, Ivan T.; Simeonov, Plamen

    2017-01-01

    Background: Basilar tip aneurysms are one of the most complex vascular lesions to treat surgically because of their location, depth of the approach, and close proximity of vital neurovascular structures such as the mesencephalon, cranial nerves, perforating arteries to the thalamus. There are different surgical approaches utilized to reach basilar tip aneurysms, namely, pterional, pretemporal, orbitozygomatic, subtemporal, and anterior petrosectomy. Each of them has its advantages and limitations. Methods: In this paper, we present our personal experience with the use of subtemporal approach. The technique is described in detail including its nuances and potential pitfalls. Results: The subtemporal approach is indicated for basilar tip aneurysms located at the level of the floor of the sella turcica to 1 cm above the dorsum sellae. Conclusion: Subtemporal approach offers good surgical corridor for the management of these complex vascular lesions. PMID:28217394

  13. Pharmacological and molecular comparison of K(ATP) channels in rat basilar and middle cerebral arteries

    DEFF Research Database (Denmark)

    Ploug, Kenneth Beri; Edvinsson, Lars; Olesen, Jes;

    2006-01-01

    ATP-sensitive potassium (K(ATP)) channels play an important role in the regulation of cerebral vascular tone. In vitro studies using synthetic K(ATP) channel openers suggest that the pharmacological profiles differ between rat basilar arteries and rat middle cerebral arteries. To address this issue....... Densitometric measurements of the Western blot signals further showed higher expression levels of Kir6.1 and SUR2B proteins in rat middle cerebral arteries than was found in rat basilar arteries. In conclusion, our in vitro pharmacological studies showed no evidence for functional endothelial K(ATP) channels...

  14. Acute stenting and thromboaspiration in basilar artery occlusions due to embolism from the dominating vertebral artery

    Energy Technology Data Exchange (ETDEWEB)

    Nedeltchev, K.; Remonda, L.; Brekenfeld, C.; Ozdoba, C.; Schroth, G. [Institute of Diagnostic and Interventional Neuroradiology, University of Bern, Inselspital, Freiburgstrasse 4, 3010, Bern (Switzerland); Do, D.D. [Institute of Angiology, University of Bern, Inselspital, Bern (Switzerland); Arnold, M.; Mattle, H.P. [Department of Neurology, University of Bern, Inselspital, Bern (Switzerland)

    2004-08-01

    Intra-arterial thrombolysis (IAT) is the only treatment that has demonstrated benefit in patients with acute basilar artery occlusions (ABAO). IAT may be difficult to perform when access to the occluded basilar artery (BA) is prevented by pathology of the vertebral arteries (VA). We report on two patients with ABAO due to embolism from the dominating VA. Catheter navigation through the occluded VA and thromboaspiration enabled access to the BA. Thromboaspiration alone or in addition to IAT resulted in a complete recanalization of the BA and a favorable clinical outcome. A stent was deployed at the site of the stenosis in the VA either prior to or immediately after BA recanalization. (orig.)

  15. Comparison between distortion product otoacoustic emissions and nerve fiber responses from the basilar papilla of the frog

    Science.gov (United States)

    Meenderink, Sebastiaan W. F.; van Dijk, Pim; Narins, Peter M.

    2005-05-01

    The basilar papilla (BP) is one of the three end organs in the frog inner ear that is sensitive to airborne sound. Its anatomy and physiology are unique among all classes of vertebrates. Essentially, the BP functions as a single auditory filter presumably arising from a mechanically-tuned mechanism. As such, both neural and distortion product otoacoustic emission (DPOAE) tuning may reflect a single mechanical filtering mechanism. Using the Duffing oscillator as a simple model for both neural and DPOAE tuning from the BP, two predictions can be made: [1] the characteristic frequency (CF) of neural tuning and the best frequency (BF) of DPOAE tuning will coincide and [2] the neural tuning curve and DPOAE-audiogram have a similar shape when the neural tuning curve is scaled by a factor of 4 along the y-axis. We recorded both neural tuning curves and DPOAE-audiograms from the BP of the leopard frog. These recordings show good agreement with the model predictions when the stimulus tones are related by relatively small stimulus frequency ratios. For larger stimulus frequency ratios, DPOAE recordings clearly deviate from model predictions. These differences are most likely caused by the oversimplified representation of the frog BP by the model. .

  16. Osteogenesis imperfecta in childhood: MR imaging of basilar impression

    Energy Technology Data Exchange (ETDEWEB)

    Janus, G.J.M. E-mail: janus@knmg.nl; Engelbert, R.H.H.; Beek, E.; Gooskens, R.H.J.M.; Pruijs, J.E.H

    2003-07-01

    Objective: To determine on radiographs the presence of Basilar Impression (BI) in children with Osteogenesis Imperfecta (OI). To confirm this sign and altered geometrical relationships of the craniocervical junction in course of time with magnetic resonance imaging (MRI). Methods and patients: In a cohort study of 130 patients with OI (OI type I: 85; OI type III: 21; OI type IV: 24) lateral radiographs of the skull and cervical spine were made in a standardised way. MRI scans were performed when BI was suspected based upon protrusion of the odontoid above Chamberlain's line. Intracranial abnormalities as well as the basal angle were described. Neurological examination was performed in patients with conclusive BI at MRI-scan. Results and discussion: In eight patients BI could be confirmed by MRI-scan. None of the children had or developed in time neurological symptoms or signs. Follow up of BI by MRI scans was done in seven patients (mean: 5 years; range: 2-6 years). No alteration of intracranial findings were seen at subsequent investigation, although in one child Chamberlain's line increased from 8 (first MRI) to 15 mm (last MRI). BI can be diagnosed by radiographs but in the extreme osteoporotic bone and altered anatomy of the craniocervical junction of children with OI MRI is preferable. As intracranial pathology can be demonstrated by MRI, also a relation can be laid to possible neurological symptoms and signs at clinical examination. Conclusion: In our cohort study no alteration of the intracranial contents was seen at subsequent MRI scans. Although anatomic deformations exist in BI, no neurological symptoms or signs were present in our study and no operative reconstruction had to be performed. Periodical MRI-scan has not been of influence on the clinical decision making process. At the moment we perform a MRI-scan if BI is suspected at lateral skull radiographs. The MRI images serve as reference findings to anticipate on possible future symptoms and

  17. Unusual origin of the left ophthalmic artery from the basilar trunk.

    Science.gov (United States)

    Rivera, Rodrigo; Choi, In Sup; Sordo, Juan Gabriel; Giacaman, Pablo; Badilla, Lautaro; Bravo, Eduardo; Echeverria, Daniel

    2015-05-01

    The formation of the ophthalmic artery (OA) is a complex process with two different proposed embryological steps for its development. Several anatomical variants have been described. We present a very unusual origin of the ophthalmic artery from the basilar trunk, in a 45-year-old male with a history of pontine hemorrhagic stroke. MRI and CTA showed evidence of previous hemorrhage in the pons and several intracranial arterial dysplastic dilatations. DSA confirmed several fusiform dilatations of the basilar trunk. In the left ICA, no ophthalmic artery was seen arising from the carotid siphon. The left ophthalmic artery arises from the basilar trunk and runs lateral to the cavernous sinus through the middle cranial fossa, entering the left orbit at the superior orbital fissure. The patient was treated conservatively. Two main theories for this anomaly are known, one from Lasjaunias and the other from Paget. To our knowledge, this basilar origin of the OA has only been described three times in the literature. For its origin, we propose a partial persistence of the trigeminal artery together with a dominance of the dorsal ophthalmic artery.

  18. Pharmacological and molecular comparison of K(ATP) channels in rat basilar and middle cerebral arteries

    DEFF Research Database (Denmark)

    Ploug, Kenneth Beri; Edvinsson, Lars; Olesen, Jes;

    2006-01-01

    ATP-sensitive potassium (K(ATP)) channels play an important role in the regulation of cerebral vascular tone. In vitro studies using synthetic K(ATP) channel openers suggest that the pharmacological profiles differ between rat basilar arteries and rat middle cerebral arteries. To address this issue...

  19. Basilar impression associated with impacted cisterna magna, spastic paraparesis and distress of balance: case report

    Directory of Open Access Journals (Sweden)

    Gonçalves da Silva José Alberto

    2006-01-01

    Full Text Available We report on a 48 years-old man with basilar impression without syringohydromyelia, in which the cisterna magna was impacted by the cerebellar tonsils. Six months after posterior fossa decompression there was the disappearance of nuchal rigidity, vertigo, spastic paraparesis and improvement of balance. Nevertheless hyperreflexia and diminished pallesthesia of the lower limbs persisted.

  20. Cross-sectional imaging for diagnosis and clinical outcome prediction of acute basilar artery thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Mortimer, A.M., E-mail: alex_mortimer@hotmail.co [Severn School of Radiology, Bristol (United Kingdom); Department of Radiology, Great Western Hospital, Swindon (United Kingdom); Saunders, T.; Cook, J.-L. [Department of Radiology, Great Western Hospital, Swindon (United Kingdom)

    2011-06-15

    Basilar artery occlusion is a potentially fatal condition and imaging findings can be subtle. Prompt diagnosis is vital, as recognition may lead to therapeutic recanalization that may improve functional outcome and survival. Furthermore, cross-sectional imaging signs may help predict eventual outcome and, therefore, guide which patients should be subjected to aggressive treatment. Computed tomography (CT) signs include a hyperdense basilar artery that has a high specificity, accuracy, positive and negative predictive value. Evidence regarding the prognostic significance of the hyperdense basilar artery sign is conflicting. Early magnetic resonance imaging (MRI) features include loss of flow void, seen as increased signal intensity within the basilar artery on T2-weigted images and identification of acute thrombus, seen as intermediate signal on T1-weighted images. MRI sequences are more sensitive for early detection of acute ischaemia or infarction, ideally with diffusion-weighted imaging (DWI). Both CT and MR angiography are sensitive for detection of acute thrombus, seen as a filling defect or occlusion. These are the non-invasive imaging techniques of choice to confirm diagnosis, with perhaps the speed and accessibility of CT angiography resulting in this technique being valuable in the acute setting. Several new scoring systems based on arterial segmentation rather than global volume assessment using CT angiography source images and DWI have shown early promise in the prediction of eventual clinical outcome in order to isolate those patients who may benefit from therapeutic recanalization.

  1. Prodromal Transient Ischemic Attack or Minor Stroke and Outcome in Basilar Artery Occlusion

    NARCIS (Netherlands)

    Conforto, Adriana B.; De Freitas, Gabriel R.; Schonewille, Wouter J.; Kappelle, L. Jaap; Algra, Ale

    2015-01-01

    Background The presence of prodromal transient ischemic attacks (TIAs) has been associated with a favorable outcome in anterior circulation stroke. We aimed to determine the association between prodromal TIAs or minor stroke and outcomes at 1 month, in the Basilar Artery International Cooperation St

  2. Prodromal Transient Ischemic Attack or Minor Stroke and Outcome in Basilar Artery Occlusion

    NARCIS (Netherlands)

    Conforto, A.B.; Freitas, G.R. de; Schonewille, W.J.; Kappelle, L.J.; Algra, A.; Leeuw, F.E. de

    2015-01-01

    BACKGROUND: The presence of prodromal transient ischemic attacks (TIAs) has been associated with a favorable outcome in anterior circulation stroke. We aimed to determine the association between prodromal TIAs or minor stroke and outcomes at 1 month, in the Basilar Artery International Cooperation S

  3. Different Imaging Strategies in Patients with Possible Basilar Artery Occlusion: Cost-Effectiveness Analysis

    NARCIS (Netherlands)

    S.E. Beyer (Sebastian E.); M.G.M. Hunink (Myriam); F. Schöberl (Florian); L. von Baumgarten; S.E. Petersen (Steffen); C. Kubisch (Christian); H. Janssen (Hendrik); B. Ertl-Wagner (Birgit); M.F. Reiser (Maximilian F.); W.H. Sommer (Wieland H.)

    2015-01-01

    textabstractBackground and Purpose-This study evaluated the cost-effectiveness of different noninvasive imaging strategies in patients with possible basilar artery occlusion. Methods-A Markov decision analytic model was used to evaluate long-term outcomes resulting from strategies using computed tom

  4. Obstrução do tronco basilar: registro de três casos

    Directory of Open Access Journals (Sweden)

    Adolfo Pou-Serradel

    1984-06-01

    Full Text Available Registro de três casos de obliteração do tronco basilar, todos êles em uma idade em que a arteriosclerose é infrequente. O diagnóstico foi confirmado angiograficamente. A evolução foi diferente em cada um deles.

  5. EFFECT OF ACUPUNCTURE ON BLOOD FLOW OF VERTEBRAL AND BASILAR ARTERIES IN STROKE PATIENTS

    Institute of Scientific and Technical Information of China (English)

    吕建明; 王伟志

    2004-01-01

    Objective: To observe the short-term effect and long-term effect of acupuncture on blood flow of vertebral and basilar arteries in stroke patients.Methods: A total of 58 stroke patients (34 males and 24 females) were agreed to participate in this study, and changes of blood flow of the vertebral and basilar arteries were detected after one week's and 45 days' continuous acupuncture treatment by using a Doppler's ultrasonic diagnosis apparatus.Bilateral Fengchi (GB 20), Wangu (GB 12), Tianzhu (BL 10), etc.were punctured and stimulated with small amplitude, high frequency and twirling-reinforcing method for 3 min.The treatment was conducted once daily.Results: Following one week's and 45 days' acupuncture treatment, diastolic velocity (DV), systolic velocity (SV) and mean velocity (MV) of the basilar artery increased significantly in comparison with pre-treatment (P0.05).Results indicated that acupuncture treatment could effectively improve blood supply of the basilar artery and regulate the uneven blood flow of the bilateral vertebral arteries.Conclusion: Acupuncture treatment can raise blood flow of the brain in stroke patients.

  6. Effects of K+ channel agonists cromakalim and pinacidil on rat basilar artery smooth muscle cells are mediated by Ca(++)-activated K+ channels.

    Science.gov (United States)

    Stockbridge, N; Zhang, H; Weir, B

    1991-11-27

    Whole-cell and cell-free inside-out patch-clamp recording techniques were used to examine the actions of potassium channel openers pinacidil and cromakalim in enzymatically isolated smooth muscle cells of rat basilar artery. Delayed rectifier and calcium-dependent potassium currents were identified from the whole-cell recordings. Only the calcium-dependent potassium current was increased by cromakalim and pinacidil. Recordings from inside-out membrane patches revealed a large conductance voltage- and calcium-dependent potassium channel, which was blocked by charybdotoxin but unaffected by ATP less than 10 mM. Cromakalim and pinacidil increased the open probability of this channel. On the basis of these results, we suggest that such drugs, acting on cerebral arterial smooth muscle cell potassium channels, may be of some benefit in the treatment of cerebral vasospasm following subarachnoid hemorrhage.

  7. Hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia: relato de caso Cruciate hemiplegia associated with basilar impression, Arnold-Chiari malformation and syringomyelia: case report

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    1996-12-01

    Full Text Available Os autores apresentam um caso de hemiplegia cruzada associada a impressão basilar, malformação de Arnold-Chiari e siringomielia. Discutem as propostas anatômicas e a fiopatogenia desta síndrome de ocorrência bastante rara.The authors report a case of cruciate hemiplegia associated with basilar impression, Chiari malformation and syringomyelia. The neuroanatomical controversy, the surgical treatment and the good outcome of the patient are discussed.

  8. The Challenge of Managing Fusiform Basilar Artery Aneurysms: From Acute Ischemic Stroke to a Massive Subarachnoid Hemorrhage

    Directory of Open Access Journals (Sweden)

    Sofia Bezerra

    2011-02-01

    Full Text Available We present the case of a patient with acute brain stem ischemic stroke who was found to have a fusiform basilar aneurysm with a thrombus within the dilated vessel. Three days after the ischemic stroke, the patient had a massive subarachnoid hemorrhage and died. This case illustrates the difficulties in the acute management of ischemic events in patients with basilar fusiform aneurysms, because the natural history of this disease encompasses both bleeding and thrombosis.

  9. Neurodynamic oscillators

    Science.gov (United States)

    Espinosa, Ismael; Gonzalez, Hortensia; Quiza, Jorge; Gonazalez, J. Jesus; Arroyo, Ruben; Lara, Ritaluz

    1995-01-01

    Oscillation of electrical activity has been found in many nervous systems, from invertebrates to vertebrates including man. There exists experimental evidence of very simple circuits with the capability of oscillation. Neurons with intrinsic oscillation have been found and also neural circuits where oscillation is a property of the network. These two types of oscillations coexist in many instances. It is nowadays hypothesized that behind synchronization and oscillation there is a system of coupled oscillators responsible for activities that range from locomotion and feature binding in vision to control of sleep and circadian rhythms. The huge knowledge that has been acquired on oscillators from the times of Lord Rayleigh has made the simulation of neural oscillators a very active endeavor. This has been enhanced with more recent physiological findings about small neural circuits by means of intracellular and extracellular recordings as well as imaging methods. The future of this interdisciplinary field looks very promising; some researchers are going into quantum mechanics with the idea of trying to provide a quantum description of the brain. In this work we describe some simulations using neuron models by means of which we form simple neural networks that have the capability of oscillation. We analyze the oscillatory activity with root locus method, cross-correlation histograms, and phase planes. In the more complicated neural network models there is the possibility of chaotic oscillatory activity and we study that by means of Lyapunov exponents. The companion paper shows an example of that kind.

  10. The efficiency analysis of thrombolytic rt-PA combined with intravascular interventional therapy in patients with acute basilar artery occlusion

    Science.gov (United States)

    Xianxian, Zhao; Chengsong, Yue; Qiang, Mei; Fei, Wei; Lin, Shen; Huiyan, Ding; Zili, Gong

    2017-01-01

    In order to further optimize the treatment strategy for the patients with acute basilar artery occlusion, we were dedicated to study the therapeutic effects and influential factors in the process of treated basilar artery occlusion with thrombolytic combined vascular interventional therapy. 75 patients with acute basilar artery occlusion treated with arterial thrombolytic therapy were analyzed retrospectively. In accordance with the discharge records of patients, their short-term curative effect with 24-hour treatment and 14-days treatment were evaluated. Our data showed that the survival condition of the patients with acute acute basilar artery occlusion were visibly improved by combination thrombolytic and interventional therapy. Moreover, their BI scores were remarkably improved, while NIHSS and mRS scores were evidently reduced. These data proved that our treatment strategy was able to improve the survival condition of patients with acute basilar artery occlusion. Furthermore, our data showed that coagulation related factors remarkably improved in the patients, when they treated by combination thrombolytic therapy with interventional therapy. In addition, our results suggested that the patients' bilateral Babinski(+), revascularization and coma symptom were closely related to their prognosis after treated the patients with combination thrombolytic and vascular interventional therapy, and the difference was statistically significant (pBabinski(+), and revascularization in the patients with acute basilar artery occlusion have an appreciable impact on the patients' prognosis. PMID:28123346

  11. Comparison of P2X receptors in rat mesenteric, basilar and septal (coronary) arteries.

    Science.gov (United States)

    Lewis, C J; Evans, R J

    2000-07-01

    alpha beta meATP-evoked concentration-dependent, PPADS-sensitive, desensitising, P2X receptor-mediated, constrictions of mesenteric, basilar and septal artery rings with EC(50) values of 1, 1 and 30 microM, respectively. In patch clamp studies on acutely dissociated artery smooth cells alpha beta meATP-evoked transient inward currents (tau approximately 100 ms) with mean current densities of approximately 340, 175 and 120 pA/pF, respectively. P2X(1) receptor immunoreactivity was expressed in mesenteric and basilar arteries and this receptor subunit appears to dominate the P2X receptor phenotype in these vessels. In contrast P2X(1) receptor immunoreactivity was not detected in septal arteries and the alpha beta meATP sensitivity of constriction was not consistent with the involvement of P2X(1) receptors. These results suggest that not all arteries share a common P2X receptor phenotype.

  12. Contractile responses to rat urotensin II in resting and depolarized basilar arteries.

    Science.gov (United States)

    Porras-González, Cristina; Ureña, Juan; Egea-Guerrero, Juan José; Gordillo-Escobar, Elena; Murillo-Cabezas, Francisco; González-Montelongo, María del Carmen; Muñoz-Sánchez, María Angeles

    2014-03-01

    The effects of human urotensin II (hUII) on the vascular tone of different animal species has been studied extensively. However, little has been reported on the vasoactive effects of rat urotensin (rUII) in murine models. The aim of the present study was to investigate the effects of rUII on vasoreactivity in rat basilar arteries. Basilar arteries from adult male Wistar rats (300-350 g) were isolated, cut in rings, and mounted on a small vessel myograph to measure isometric tension. rUII concentrations were studied in both resting and depolarized state. To remove endothelial nitric oxide effects from the rUII response, we treated selected arterial rings with Nω-nitro-L-arginine methyl ester (L-NAME). 10 μM rUII produced a potent vasoconstrictor response in rat basilar arteries with intact endothelium, while isometric forces remained unaffected in arterial rings treated with lower rUII concentrations. Although L-NAME did not have a significant effect on 10 μM rUII-evoked contraction, it slightly increased arterial ring contraction elicited by 1 μM rUII. In depolarized arteries, dose-dependent rUII increased depolarization-induced contractions. This effect was suppressed by L-NAME. Our results show that the rat basilar artery has a vasoconstrictor response to rUII. The most potent vasoconstrictor effect was produced by lower doses of rUII (0.1 and 1 μM) in depolarized arteries with intact endothelium. This effect could facilitate arterial vasospasm in vascular pathophysiological processes such as subarachnoid hemorrhage and hypertension, when sustained depolarization and L-type Ca(2+) channel activation are present.

  13. Basilar invagination secondary to hypoplasia of the clivus - Is there indication for craniocervical fixation?

    OpenAIRE

    2014-01-01

    The posterior fossa decompression is a form of treatment suggested for patients with basilar invagination (BI) secondary to hypoplasia symptomatic of the clivus and atlantoaxial alignment preserved. Based on the fact that the worsening of cranial-cervical kyphosis (decrease of clivus-canal angle to less than 150o) can result in anterior brainstem compression, we propose that some patients may benefit from the cranio-cervical fixation. We present a case report of a patient with BI secondary to...

  14. Meixner oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Atakishiyev, N.M. [Instituto de Matematicas. Universidad Nacional Autonoma de Mexico. Cuernavaca, Morelos (Mexico); Jafarov, E.I.; Nagiyev, S.M. [Institute of Physics, Azerbaijan Academy of Sciences. Baku, Azerbaijan (Azerbaijan); Wolf, K.B. [Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas. Universidad Nacional Autonoma de Mexico. Cuernavaca, Morelos (Mexico)

    1998-10-01

    Meixner oscillators have a ground state and an energy spectrum that is equally spaced; they are a two-parameter family of models that satisfy a Hamiltonian equation with a difference operator. Meixner oscillators include as limits and particular cases the Charlier, Kravchuk and Hermite (common quantum-mechanical) harmonic oscillators. By the Sommerfeld-Watson transformation they are also related with a relativistic model of the linear harmonic oscillator, built in terms of the Meixner-Pollaczek polynomials, and their continuous weight function. We construct explicitly the corresponding coherent states with the dynamical symmetry group Sp(2,R). The reproducing kernel for the wavefunctions of these models is also found. (Author)

  15. RESULTS OF THE USE OF PEEK CAGES IN THE TREATMENT OF BASILAR INVAGINATION BY GOEL TECHNIQUE

    Directory of Open Access Journals (Sweden)

    Luís Eduardo Carelli Teixeira da Silva

    2016-03-01

    Full Text Available ABSTRACT Objective: Analysis of the use of polyetheretherketone (PEEK cages for atlantoaxial facet realignment and distraction for treatment of basilar invagination by Goel technique. Method: Retrospective descriptive statistical analysis of the neurological status, pain, presence of subsidence and bone fusion with the use of PEEK cages in 8 atlantoaxial joints of 4 patients with basilar invagination. All patients were treated with atlantoaxial facet distraction and realignment and subsequent arthrodesis C1-C2 by the technique of Goel modified by the use of PEEK cage. Results: All patients showed improvement in Nurick neurological assessment scale and Visual Analogue Scale (VAS of pain. There were no cases of subsidence, migration, or damage to the vertebral artery during the insertion of the cage. All joints evolved with bone fusion, assessed by dynamic radiographs, and computed tomography. Two patients developed neuropathic pain in dermatome of C2 and one patient had unilateral vertebral artery injury during C2 instrumentation treated with insertion of pedicle screw to control the bleeding. Conclusion: The results of the treatment of basilar invagination by the Goel technique with the use of PEEK cages shown to be effective and safe although further studies are needed to confirm this use.

  16. A Vertebral Artery Dissection with Basilar Artery Occlusion in a Child

    Directory of Open Access Journals (Sweden)

    Katleen Devue

    2014-01-01

    Full Text Available This paper presents the case report of an 11-year-old boy with an acute dissection with thrombosis of the left vertebral artery and thrombosis of the basilar artery. The patient was treated with acute systemic thrombolysis, followed by intra-arterial thrombolysis, without any clinical improvement, showing left hemiplegia, bilateral clonus, hyperreflexia, and impaired consciousness. MRI indicated persistent thrombosis of the arteria basilaris with edema and ischemia of the right brainstem. Heparinization for 72 hours, followed by a two-week LMWH treatment and subsequent oral warfarin therapy, resulted in a lasting improvement of the symptoms. Vertebral artery dissection after minor trauma is rare in children. While acute basilar artery occlusion as a complication is even more infrequent, it is potentially fatal, which means that prompt diagnosis and treatment are imperative. The lack of class I recommendation guidelines for children regarding treatment of vertebral artery dissection and basilar artery occlusion means that initial and follow-up management both require a multidisciplinary approach to coordinate emergency, critical care, interventional radiology, and child neurology services.

  17. Megadolicho basilar artery as a cause of asymmetrical sensorineural hearing loss - case report

    Directory of Open Access Journals (Sweden)

    Melo, Antonio Antunes

    2011-07-01

    Full Text Available Introduction: At the differentiated diagnosis of asymmetrical sensorineural hearing losses, vascular disorders are present, one of which is megadolicho basilar artery. This disease is generally asymptomatic, and when symptoms are found, they can be caused by a compression or ischemia. Clinically, sensorineural hearing loss, tinnitus, headache, facial hypoesthesia, trigeminal neuralgia, vertigo, diplopia and facial palsy, among others, are likely to occur. The image examination of choice for its diagnosis is nuclear magnetic resonance. The megadolicho basilar artery therapy can be surgical or conservative, according to the associated findings. A multidisciplinary approach, including a neurologist, neurosurgeon and an otorhinolaryngologist is recommended for a proper administration of the case. Objective: Report the case of a patient with asymmetrical sensorineural hearing loss, diagnosed of megadolicho basilar artery. Case report: JBS, 57-year-old white male with a history of asymmetrical sensorineural hearing loss and bilateral whistle-like tinnitus for several years. The otorhinolaryngologic evaluation, including otoscopy, anterior rhinoscopy and oral pharynx, was normal. Final Comments: The treatment consisted in following up with the patient, controlling the tinnitus by drugs and using an individual sound amplification apparatus on the left ear.

  18. The challenge of basilar artery occlusion wake-up stroke: too late for intravenous thrombolysis?

    Science.gov (United States)

    Caliandro, Pietro; Reale, Giuseppe; Tartaglione, Tommaso; Rossini, Paolo Maria

    2016-07-01

    We describe the case of a patient carried to our emergency department, with the wake-up finding of dysarthria, right hemiplegia and worsening consciousness impairment (NIHSS 12). After performing a CT angiography, which showed complete basilar occlusion, we determined the MR DWI-FLAIR mismatch to estimate the stroke onset time. Because of the favorable mismatch (DWI hyperintensity in the left pons, no FLAIR hyperintensity in the same region), the patient underwent thrombolysis with sudden neurological improvement. In addition, the DWI hyperintensity first observed in the left pons totally regressed after thrombolysis. Wake-up stroke constitutes about 14 % of all strokes, while the percentage of basilar artery occlusion wake-up strokes is still unknown. Although thrombolysis in patients with unknown-onset time is still an off-label therapy, basilar artery occlusion is a potentially fatal event. In our case we used RM DWI-FLAIR mismatch to rapidly estimate the stroke onset time and to treat the patient with an off-label but potentially effective and safe therapy.

  19. Oscillate Boiling

    CERN Document Server

    Li, Fenfang; Nguyen, Dang Minh; Ohl, Claus-Dieter

    2016-01-01

    We report about an intriguing boiling regime occurring for small heaters embedded on the boundary in subcooled water. The microheater is realized by focusing a continuous wave laser beam to about $10\\,\\mu$m in diameter onto a 165\\,nm-thick layer of gold, which is submerged in water. After an initial vaporous explosion a single bubble oscillates continuously and repeatably at several $100\\,$kHz. The microbubble's oscillations are accompanied with bubble pinch-off leading to a stream of gaseous bubbles into the subcooled water. The self-driven bubble oscillation is explained with a thermally kicked oscillator caused by the non-spherical collapses and by surface pinning. Additionally, Marangoni stresses induce a recirculating streaming flow which transports cold liquid towards the microheater reducing diffusion of heat along the substrate and therefore stabilizing the phenomenon to many million cycles. We speculate that this oscillate boiling regime may allow to overcome the heat transfer thresholds observed dur...

  20. Transient basilar artery occlusion monitored by transcranial color Doppler presenting with a spectacular shrinking deficit: a case report

    Directory of Open Access Journals (Sweden)

    Del Sette Massimo

    2010-01-01

    Full Text Available Abstract Introduction We describe the case of a 79-year-old Caucasian Italian woman with a transient basilar occlusion monitored by transcranial Doppler, with subsequent recanalization and clinical shrinking deficit. This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. This case is important and needs to be reported because transient basilar occlusion may be easily diagnosed if transcranial Doppler is performed. Case presentation A 79-year-old woman affected by chronic atrial fibrillation and not treated with oral anticoagulants, cardioverted to sinus rhythm during a gastric endoscopy. She then showed a sudden-onset loss of consciousness, horizontal and vertical gaze palsy, tetraparesis and bilateral miosis and coma. Two hours later, the symptoms resolved quickly, leaving no residual neurologic deficits. Transcranial Doppler examination showed a dampened flow in the basilar artery in the emergency examination and a restored flow when the symptoms resolved. Conclusion This is the first case of transient basilar occlusive disease diagnosed and monitored by transcranial Doppler. We believe that transcranial Doppler should be performed in all cases of unexplained acute loss of consciousness, in particular, if associated with signs of brainstem dysfunctions.

  1. Subthreshold membrane potential oscillations in inferior olive neurons are dynamically regulated by P/Q- and T-type calcium channels: a study in mutant mice.

    Science.gov (United States)

    Choi, Soonwook; Yu, Eunah; Kim, Daesoo; Urbano, Francisco J; Makarenko, Vladimir; Shin, Hee-Sup; Llinás, Rodolfo R

    2010-08-15

    The role of P/Q- and T-type calcium channels in the rhythmic oscillatory behaviour of inferior olive (IO) neurons was investigated in mutant mice. Mice lacking either the CaV2.1 gene of the pore-forming alpha1A subunit for P/Q-type calcium channel, or the CaV3.1 gene of the pore-forming alpha1G subunit for T-type calcium channel were used. In vitro intracellular recording from IO neurons reveals that the amplitude and frequency of sinusoidal subthreshold oscillations (SSTOs) were reduced in the CaV2.1-/- mice. In the CaV3.1-/- mice, IO neurons also showed altered patterns of SSTOs and the probability of SSTO generation was significantly lower (15%, 5 of 34 neurons) than that of wild-type (78%, 31 of 40 neurons) or CaV2.1-/- mice (73%, 22 of 30 neurons). In addition, the low-threshold calcium spike and the sustained endogenous oscillation following rebound potentials were absent in IO neurons from CaV3.1-/- mice. Moreover, the phase-reset dynamics of oscillatory properties of single neurons and neuronal clusters in IO were remarkably altered in both CaV2.1-/- and CaV3.1-/- mice. These results suggest that both alpha1A P/Q- and alpha1G T-type calcium channels are required for the dynamic control of neuronal oscillations in the IO. These findings were supported by results from a mathematical IO neuronal model that incorporated T and P/Q channel kinetics.

  2. Sensitivity of Hyperdense Basilar Artery Sign on Non-Enhanced Computed Tomography.

    Directory of Open Access Journals (Sweden)

    Marielle Ernst

    Full Text Available The hyperdense basilar artery sign (HBAS is an indicator of vessel occlusion on non contrast-enhanced computer tomography (NECT in acute stroke patients. Since basilar artery occlusion (BAO is associated with a high mortality and morbidity, its early detection is of great clinical value. We sought to analyze the influence of density measurement as well as a normalized ratio of Hounsfield unit/hematocrit (HU/Hct ratio on the detection of BAO on NECT in patients with suspected BAO.102 patients with clinically suspected BAO were examined with NECT followed immediately by Multidetector computed tomography Angiography. Two observers independently analyzed the images regarding the presence or absence of HBAS on NECT and performed HU measurements in the basilar artery. Receiver operating characteristic curve analysis was performed to determine the optimal density threshold for BAO using attenuation measurements or HU/Hct ratio.Sensitivity of visual detection of the HBAS on NECT was relatively low 81% (95%-CI, 54-95% while specificity was high 91% (95%-CI, 82-96%. The highest sensitivity was achieved by the combination of visual assessment and additional quantitative attenuation measurements applying a cut-off value of 46.5 HU with 94% sensitivity and 81% specificity for BAO. A HU/Hct ratio >1.32 revealed sensitivity of 88% (95%-CI, 60-98% and specificity of 84% (95%-CI, 74-90%.In patients with clinically suspected acute BAO the combination of visual assessment and additional attenuation measurement with a cut-off value of 46.5 HU is a reliable approach with high sensitivity in the detection of BAO on NECT.

  3. Oscillation death in coupled oscillators

    Institute of Scientific and Technical Information of China (English)

    Wei ZOU; Xin-gang WANG; Qi ZHAO; Meng ZHAN

    2009-01-01

    We study dynamical behaviors in coupled nonlinear oscillators and find that under certain condi- tions, a whole coupled oscillator system can cease oscil- lation and transfer to a globally nonuniform stationary state [I.e., the so-called oscillation death (OD) state], and this phenomenon can be generally observed. This OD state depends on coupling strengths and is clearly differ- ent from previously studied amplitude death (AD) state, which refers to the phenomenon where the whole system is trapped into homogeneously steady state of a fixed point, which already exists but is unstable in the ab- sence of coupling. For larger systems, very rich pattern structures of global death states are observed. These Turing-like patterns may share some essential features with the classical Turing pattern.

  4. Successful treatment of a giant pediatric fusiform basilar trunk aneurysm with surpass flow diverter.

    Science.gov (United States)

    Kan, Peter; Mokin, Maxim; Puri, Ajit S; Wakhloo, Ajay K

    2016-06-01

    Fusiform aneurysms present a unique challenge to traditional microsurgical and endovascular treatment because of the lack of a discernible neck and the involvement of parent vessel. Flow diversion has increasingly become the treatment of choice for fusiform aneurysms in the anterior circulation, but its results in the posterior circulation are variable. We report successful treatment of a giant fusiform upper basilar trunk aneurysm with the Surpass flow diverter in an adolescent, and discuss the potential advantages of this emerging technology in the treatment of fusiform posterior circulation aneurysms.

  5. Basilar invagination secondary to hypoplasia of the clivus - Is there indication for craniocervical fixation?

    Directory of Open Access Journals (Sweden)

    Andrei Fernandes Joaquim

    2014-03-01

    Full Text Available The posterior fossa decompression is a form of treatment suggested for patients with basilar invagination (BI secondary to hypoplasia symptomatic of the clivus and atlantoaxial alignment preserved. Based on the fact that the worsening of cranial-cervical kyphosis (decrease of clivus-canal angle to less than 150o can result in anterior brainstem compression, we propose that some patients may benefit from the cranio-cervical fixation. We present a case report of a patient with BI secondary to clivus hypoplasia who underwent cranio-cervical fixation in extension, with a reduction in clivus-canal angle and improvement of symptoms without posterior fossa decompression.

  6. Successful treatment of a giant pediatric fusiform basilar trunk aneurysm with surpass flow diverter.

    Science.gov (United States)

    Kan, Peter; Mokin, Maxim; Puri, Ajit S; Wakhloo, Ajay K

    2015-06-03

    Fusiform aneurysms present a unique challenge to traditional microsurgical and endovascular treatment because of the lack of a discernible neck and the involvement of parent vessel. Flow diversion has increasingly become the treatment of choice for fusiform aneurysms in the anterior circulation, but its results in the posterior circulation are variable. We report successful treatment of a giant fusiform upper basilar trunk aneurysm with the Surpass flow diverter in an adolescent, and discuss the potential advantages of this emerging technology in the treatment of fusiform posterior circulation aneurysms.

  7. Neutrino Oscillations

    Directory of Open Access Journals (Sweden)

    G. Bellini

    2014-01-01

    Full Text Available In the last decades, a very important breakthrough has been brought about in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has been crossed by this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future.

  8. Oscillations of a chemical garden

    Science.gov (United States)

    Pantaleone, J.; Toth, A.; Horvath, D.; Rother McMahan, J.; Smith, R.; Butki, D.; Braden, J.; Mathews, E.; Geri, H.; Maselko, J.

    2008-04-01

    When soluble metal salts are placed in a silicate solution, chemical gardens grow. These gardens are treelike structures formed of long, thin, hollow tubes. Here we study one particular case: a calcium nitrate pellet in a solution of sodium trisilicate. We observe that tube growth results from a relaxation oscillation. The average period and the average growth rate are approximately constant for most of the structures growth. The period does fluctuate from cycle to cycle, with the oscillation amplitude proportional to the period. Based on our observations, we develop a model of the relaxation oscillations which calculates the average oscillation period and the average tube radius in terms of fundamental membrane parameters. We also propose a model for the average tube growth rate. Predictions are made for future experiments.

  9. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  10. Antiperiodic oscillations

    Science.gov (United States)

    Freire, Joana G.; Cabeza, Cecilia; Marti, Arturo; Pöschel, Thorsten; Gallas, Jason A. C.

    2013-06-01

    The investigation of regular and irregular patterns in nonlinear oscillators is an outstanding problem in physics and in all natural sciences. In general, regularity is understood as tantamount to periodicity. However, there is now a flurry of works proving the existence of ``antiperiodicity'', an unfamiliar type of regularity. Here we report the experimental observation and numerical corroboration of antiperiodic oscillations. In contrast to the isolated solutions presently known, we report infinite hierarchies of antiperiodic waveforms that can be tuned continuously and that form wide spiral-shaped stability phases in the control parameter plane. The waveform complexity increases towards the focal point common to all spirals, a key hub interconnecting them all.

  11. Endothelin-1 and endothelin receptors in the basilar artery of the capybara.

    Science.gov (United States)

    Loesch, Andrzej; Gajkowska, Barbara; Dashwood, Michael R; Fioretto, Emerson T; Gagliardo, Karina M; Lima, Ana R De; Ribeiro, Antonio A C M

    2005-02-01

    Little is known about cerebral vasculature of capybara, which seems may serve as a natural model of studying changes in cerebral circulation due to internal carotid artery atrophy at animal sexual maturation. This is the first study of the light- and electron-immunocytochemical localisation of endothelin-1 (ET-1) and ETA and ETB endothelin receptors in the basilar artery of capybaras (6 to 12-month-old females and males) using an ExtrAvidin detection method. All animals examined showed similar patterns of immunoreactivity. Immunoreactivity for ET-1 was detected in the endothelium and adventitial fibroblasts, whilst immunoreactivity for ETA and ETB receptors was present in the endothelium, vascular smooth muscle, perivascular nerves and fibroblasts. In endothelial cells immunoreactivity to ET-1 was pronounced in the cytoplasm or on the granular endoplasmic reticulum. Similar patterns of immunolabelling were observed for ETA and ETB receptors, though cytoplasmic location of clusters of immunoprecipitate seems dominant. These results suggest that the endothelin system is present throughout the wall of the basilar artery of capybara.

  12. High cervical C3-4 ′disc′ compression associated with basilar invagination

    Directory of Open Access Journals (Sweden)

    Goel Atul

    2008-01-01

    Full Text Available A 20-year-old male had torticollis and short neck since birth. He presented with symptom of progressive quadriparesis over a two-year period. Investigations revealed basilar invagination with marked rotation in the craniovertebral region and relatively large C3-4 region osteophytes. Serial MRI over two years showed persistent signal opposite C3-4 disc space suggestive of cord compression. Although the cord was humped over the odontoid process, there was no clear radiological evidence that the cord was compromised at this level. During surgery, instability was identified only at the craniovertebral region and not at the level of C3-4. Distraction of the lateral masses of atlas and axis and fixation using interarticular spacers and bone graft and direct screw implantation in the lateral mass of the atlas and pars of the axis resulted in reduction of the basilar invagination and of atlantoaxial dislocation. The patient had marked clinical recovery, despite the fact that no direct procedure was done for C3-4 disc decompression. The case suggests that C3-4 disc changes could be secondary to primary instability at the craniovertebral junction.

  13. 'Top of the basilar' syndrome. Clinico-radiological evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Masaharu; Kuroda, Ryotaro; Nakatani, Jiro; Watanabe, Masaru; Akai, Fumiharu; Ioku, Masahiko

    1988-06-01

    Seventeen patients (age 23 - 81) having the ''top of the basilar'' syndrome were the subjects of this study. They were evaluated clinico-radiologically. The diagnosis of this syndrome was made by computerized tomography. The infarcted lesions of each patient were widely distributed in many areas among the thalamus, midbrain, pons, cerebellum, and occipital lobe. Both the thalami were involved in 8 patients. When the thalamus was involved bilaterally, the low density areas of both the thalami were demonstrated to be almost the same in size and symmetric in localization by computerized tomography, showing a characteristic pattern. Further, magnetic resonance imaging could reveal small lesions in the brain stem minutely. Angiography revealed that stenosis or occlusion was within the circle of 2 cm in diameter surrounding the five-forked road of the top of the basilar artery in 84.6 %. Recanalization of the occluded artery occurred in 61.5 %, which suggests that the embolism plays an important role in appearance of this syndrome. In spite of frequent recanalization hemorrhagic infarction never occurred. The prognosis was very poor.

  14. Computational fluid dynamics evaluation of flow reversal treatment of giant basilar tip aneurysm.

    Science.gov (United States)

    Alnæs, Martin Sandve; Mardal, Kent-Andre; Bakke, Søren; Sorteberg, Angelika

    2015-10-01

    Therapeutic parent artery flow reversal is a treatment option for giant, partially thrombosed basilar tip aneurysms. The effectiveness of this treatment has been variable and not yet studied by applying computational fluid dynamics. Computed tomography images and blood flow velocities acquired with transcranial Doppler ultrasonography were obtained prior to and after bilateral endovascular vertebral artery occlusion for a giant basilar tip aneurysm. Patient-specific geometries and velocity waveforms were used in computational fluid dynamics simulations in order to determine the velocity and wall shear stress changes induced by treatment. Therapeutic parent artery flow reversal lead to a dramatic increase in aneurysm inflow and wall shear stress (30 to 170 Pa) resulting in an increase in intra-aneurysmal circulation. The enlargement of the circulated area within the aneurysm led to a re-normalization of the wall shear stress and the aneurysm remained stable for more than 8 years thereafter. Therapeutic parent artery flow reversal can lead to unintended, potentially harmful changes in aneurysm inflow which can be quantified and possibly predicted by applying computational fluid dynamics.

  15. Successful coil embolization of a ruptured basilar artery aneurysm in a child with leukemia: a case report.

    Science.gov (United States)

    Hayashi, Shihori; Maehara, Taketoshi; Mukawa, Maki; Aoyagi, Masaru; Yoshino, Yoshikazu; Nemoto, Shigeru; Ono, Toshiaki; Ohno, Kikuo

    2014-01-01

    Ruptured intracranial aneurysms are rare in the pediatric population compared to adults. This has incited considerable discussion on how to treat children with this condition. Here, we report a child with a ruptured saccular basilar artery aneurysm that was successfully treated with coil embolization. A 12-year-old boy with acute lymphoblastic leukemia and accompanying abdominal candidiasis after chemotherapy suddenly complained of a severe headache and suffered consciousness disturbance moments later. Computed tomography scans and cerebral angiography demonstrated acute hydrocephalus and subarachnoid hemorrhage caused by saccular basilar artery aneurysm rupture. External ventricular drainage was performed immediately. Because the patient was in severe condition and did not show remarkable signs of central nervous system infection in cerebrospinal fluid studies, we applied endovascular treatment for the ruptured saccular basilar artery aneurysm, which was successfully occluded with coils. The patient recovered without new neurological deficits after ventriculoperitoneal shunting. Recent reports indicate that both endovascular and microsurgical techniques can be used to effectively treat ruptured cerebral aneurysms in pediatric patients. A minimally invasive endovascular treatment was effective in the present case, but long-term follow-up will be necessary to confirm the efficiency of endovascular treatment for children with ruptured saccular basilar artery aneurysms.

  16. Elongation and dilatation of the basilar artery in CT imaging; Wydluzenie i poszerzenie tetnicy podstawowej w obrazie KT

    Energy Technology Data Exchange (ETDEWEB)

    Lasek, W.; Burzynska-Makuch, M.; Pilecki, S.; Grzegorzewski, M.; Boron, Z. [Akademia Medyczna, Bydgoszcz (Poland)

    1994-12-31

    During two years 5 rare cases of elongation and dilatation of basilar artery were recognized in CT examination. In patients with cranial nerve deficits, cerebellar, brainstem and ponto-cerebellar angle signs artery megadolichobasilaris should be taken into account. CT examination is the sufficient method to see the diagnosis. (author). 15 refs, 3 tabs, 4 figs.

  17. Transfundal stent placement for treatment of complex basilar tip aneurysm: technical note

    Science.gov (United States)

    Vasquez, Ciro; Hubbard, Molly; Jagadeesan, Bharathi Dasan; Tummala, Ramachandra Prasad

    2014-01-01

    We describe a case where a complex unruptured basilar tip aneurysm was treated with a unique method of stent-assisted coil embolization. The aneurysm was considered to have a complex anatomy since both the left posterior cerebral artery and left superior cerebellar artery originated from the dome of the aneurysm. Also, the right posterior cerebral artery was incorporated in the aneurysm neck and needed to be protected prior to coil embolization. This case describes placement of a stent across the span of the aneurysm fundus in order to preserve the two branches arising from it, and the aneurysm dome was coiled without any complication. Using modifications of existing strategies for stent-assisted coil embolization, the aneurysm was treated without any complications and all of the vessels at risk were preserved. PMID:25336546

  18. Incidence of basilar invagination in patients with tonsillar herniation ? a case control craniometrical study

    Directory of Open Access Journals (Sweden)

    Andrei F Joaquim

    2014-09-01

    Full Text Available A retrospective case-control study based on craniometrical evaluation was performed to evaluate the incidence of basilar invagination (BI. Patients with symptomatic tonsillar herniation treated surgically had craniometrical parameters evaluated based on CT scan reconstructions before surgery. BI was diagnosed when the tip of the odontoid trespassed the Chamberlain’s line in three different thresholds found in the literature: 2, 5 or 6.6 mm. In the surgical group (SU, the mean distance of the tip of the odontoid process above the Chamberlain’s line was 12 mm versus 1.2 mm in the control (CO group (p<0.0001. The number of patients with BI according to the threshold used (2, 5 or 6.6 mm in the SU group was respectively 19 (95%, 16 (80% and 15 (75% and in the CO group it was 15 (37%, 4 (10% and 2 (5%.

  19. Computational Fluid Dynamics modeling of contrast transport in basilar aneurysms following flow-altering surgeries.

    Science.gov (United States)

    Vali, Alireza; Abla, Adib A; Lawton, Michael T; Saloner, David; Rayz, Vitaliy L

    2017-01-04

    In vivo measurement of blood velocity fields and flow descriptors remains challenging due to image artifacts and limited resolution of current imaging methods; however, in vivo imaging data can be used to inform and validate patient-specific computational fluid dynamics (CFD) models. Image-based CFD can be particularly useful for planning surgical interventions in complicated cases such as fusiform aneurysms of the basilar artery, where it is crucial to alter pathological hemodynamics while preserving flow to the distal vasculature. In this study, patient-specific CFD modeling was conducted for two basilar aneurysm patients considered for surgical treatment. In addition to velocity fields, transport of contrast agent was simulated for the preoperative and postoperative conditions using two approaches. The transport of a virtual contrast passively following the flow streamlines was simulated to predict post-surgical flow regions prone to thrombus deposition. In addition, the transport of a mixture of blood with an iodine-based contrast agent was modeled to compare and verify the CFD results with X-ray angiograms. The CFD-predicted patterns of contrast flow were qualitatively compared to in vivo X-ray angiograms acquired before and after the intervention. The results suggest that the mixture modeling approach, accounting for the flow rates and properties of the contrast injection, is in better agreement with the X-ray angiography data. The virtual contrast modeling assessed the residence time based on flow patterns unaffected by the injection procedure, which makes the virtual contrast modeling approach better suited for prediction of thrombus deposition, which is not limited to the peri-procedural state.

  20. Spontaneous regression of a giant basilar artery aneurysm in a young adult after surgical injury:case report and literature review

    Institute of Scientific and Technical Information of China (English)

    ZHANG He; LI Ming-hua; WANG Chun; LI Yong-dong; XU Tao

    2007-01-01

    A giant basilar artery aneurysm of young woman with endocrine disturbance was misdiagnosed as a large pituitary adenoma and treated surgically via a trans-sphenoidal approach was planned.But the neurosurgery was finally aborted because of massive bleeding during the procedure. One year later, a cerebral angiography confirmed this basilar artery aneurysm was obviously regressed and then endovascular coiling was successfully performed. No neurological complication occurred post-procedure and the endocrine dysfunction symptom was obviously improved.

  1. 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...

  2. [Endovascular treatment of critical basilar stenosis with a Solitaire® stent device: a first experience in our centre].

    Science.gov (United States)

    Mulero, Patricia; Cortijo-García, Elisa; Ruiz-Piñero, Marina; Pérez-Fernández, Santiago; Arenillas-Lara, Juan F; Martínez-Galdámez, Mario

    2014-08-01

    Introduccion. Aunque la arterioesclerosis intracraneal es una causa importante de ictus, la actitud terapeutica no esta claramente establecida. En este sentido, el estudio SAMMPRIS comparo el tratamiento medico intensivo con la angioplastia y colocacion de stent, con resultados favorables al tratamiento farmacologico. Estos resultados podrian, en parte, deberse al dispositivo utilizado (stent Wingspan ®). Caso clinico. Varon de 71 años con una estenosis grave de la arteria basilar, en quien se repetian episodios de focalidad neurologica transitoria a pesar del tratamiento con doble antiagregacion y estatinas. En estas circunstancias se decidio realizar una arteriografia terapeutica con angioplastia y colocacion de un stent Solitaire ® para optimizar resultados y se logro una estenosis residual del 40%. La evolucion fue favorable y los controles posteriores muestran una minima progresion. Conclusion. Segun nuestro conocimiento, este es el primer caso publicado de tratamiento de una estenosis critica de la arteria basilar mediante la colocacion de un stent Solitaire ®.

  3. Clinical characteristics of basilar artery syndrome%基底动脉尖综合征的临床特点

    Institute of Scientific and Technical Information of China (English)

    成亚琴

    2013-01-01

    Objective To investigate the clinical manifestations and imaging characteristics of the basilar artery syndrome. Methods A retrospective analysis of 32 cases with acute basilar artery syndrome was made. Results The patients were all acute onset with dizziness and vomiting in 12 cases,blurred vision in 3 cases, slurred speech in 14 cases, disturbance of consciousness in 16 cases, lmb paralysis in 14 case, unsteady gait in 5 cases, and headache and vomiting in 1 case. Multiple lesions were seen on the cerebral imagings in all patients. Conclusion The clinical manifestations of the basilar artery syndrome are veriable and complex with mild paralysis. MRI is helpful in the early diagnosis of the basilar artery syndrome.%目的 探讨基底动脉尖综合征的临床表现及影像学特点.方法 回顾性分析32例急性基底动脉尖综合征患者的临床资料.结果 32例患者均为急性起病,临床表现为眩晕、呕吐12例,视物不清3例,言语不清14例,意识障碍16例,肢体瘫痪14例,行走不稳5例,起病时仅感头痛、呕吐1例.所有患者头颅影像学检查均发现多发性病灶.结论 基底动脉尖综合征临床表现复杂多样,瘫痪程度较轻,MRI成像有助于早期确诊.

  4. 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...... with negative resistance), Kennedy's Colpitts-oscillator (with and without chaos) and a new 4'th order oscillator with hyper-chaos....

  5. Oscillations in glycolysis in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kloster, Antonina; Olsen, Lars Folke

    2012-01-01

    also decreases by stimulating the ATPase activity, e.g. by FCCP or Amphotericin B. Thus, ATPase activity strongly affects the glycolytic oscillations. We discuss these data in relation to a simple autocatalytic model of glycolysis which can reproduce the experimental data and explain the role...... of membrane-bound ATPases . In addition we also studied a recent detailed model of glycolysis and found that, although thismodel faithfully reproduces the oscillations of glycolytic intermediates observed experimentally, it is not able to explain the role of ATPase activity on the oscillations....

  6. Oscillating Permanent Magnets.

    Science.gov (United States)

    Michaelis, M. M.; Haines, C. M.

    1989-01-01

    Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)

  7. Solar neutrinos: Oscillations or No-oscillations?

    CERN Document Server

    Smirnov, A Yu

    2016-01-01

    The Nobel prize in physics 2015 has been awarded "... for the discovery of neutrino oscillations which show that neutrinos have mass". While SuperKamiokande (SK), indeed, has discovered oscillations, SNO observed effect of the adiabatic (almost non-oscillatory) flavor conversion of neutrinos in the matter of the Sun. Oscillations are irrelevant for solar neutrinos apart from small $\

  8. Chronic basilar artery dissection with an associated symptomatic aneurysm presenting with massive subarachnoid hemorrhage.

    Science.gov (United States)

    Cohen, José E; Moscovici, Samuel; Rajz, Gustavo; Vargas, Andres; Itshayek, Eyal

    2016-08-01

    Basilar artery dissection (BAD) is a rare condition with a worse prognosis than a dissection limited to the vertebral artery. We report a rare case of chronic BAD with an associated symptomatic aneurysm presenting with massive subarachnoid hemorrhage (SAH) in a 54-year-old woman. The diagnosis of acute BAD could only be made retrospectively, based on clinical and neuroradiological studies from a hospital admission 10months earlier. Angiography performed after her SAH showed unequivocal signs of imperfect healing; she was either post-recanalization of a complete occlusion or post-dissection. Residual multi-channel intraluminal defects led to the development of a small aneurysm, which was responsible for the massive hemorrhage. The occurrence of an associated aneurysm, and wall disease, but not an intraluminal process, reinforces the diagnosis of dissection. The patient was fully recovered at 90day follow-up. This case reinforces the need for long-term neuroradiological surveillance after non-hemorrhagic intracranial dissections to detect the development of de novo aneurysms.

  9. Oscillations of Eccentric Pulsons

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Groenbech-Jensen, Niels; Lomdahl, Peter;

    1997-01-01

    Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct.......Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct....

  10. Double-barrel Y-configuration stenting for flow diversion of a giant recurrent basilar apex aneurysm with the pipeline flex embolization device

    Directory of Open Access Journals (Sweden)

    Dale Ding

    2016-01-01

    Full Text Available Giant basilar apex aneurysms are extremely challenging to successfully manage. The Pipeline Flex embolization device (PFED is a new generation flow-diverting stent with a modified delivery system which allows resheathing of the stent after partial deployment. We describe a case of double-barrel Y-configuration stenting of a giant, recurrent basilar apex aneurysm using the PFED. A 73-year-old male was previously treated for an unruptured 11-mm basilar apex aneurysm with stent-assisted coiling using a Neuroform stent. The aneurysm was retreated twice with repeat coiling. After the third recurrence and persistent aneurysm growth into a giant, symptomatic lesion, we decided to proceed with flow diversion. We performed Y-stenting of the basilar bifurcation using three PFEDs, and was recoiled the aneurysm sac. Due to the low porosity of the flow diverters, a side-by-side double-barrel configuration was necessary in the basilar artery. Without the PFED's resheathable capability, it would not have been possible to perform Y-stenting with flow diverters.

  11. Double-barrel Y-configuration Stenting for Flow Diversion of a Giant Recurrent Basilar Apex Aneurysm with the Pipeline Flex Embolization Device.

    Science.gov (United States)

    Ding, Dale; Starke, Robert M; McGuinness, Ben; Brew, Stefan

    2016-12-01

    Giant basilar apex aneurysms are extremely challenging to successfully manage. The Pipeline Flex embolization device (PFED) is a new generation flow-diverting stent with a modified delivery system which allows resheathing of the stent after partial deployment. We describe a case of double-barrel Y-configuration stenting of a giant, recurrent basilar apex aneurysm using the PFED. A 73-year-old male was previously treated for an unruptured 11-mm basilar apex aneurysm with stent-assisted coiling using a Neuroform stent. The aneurysm was retreated twice with repeat coiling. After the third recurrence and persistent aneurysm growth into a giant, symptomatic lesion, we decided to proceed with flow diversion. We performed Y-stenting of the basilar bifurcation using three PFEDs, and was recoiled the aneurysm sac. Due to the low porosity of the flow diverters, a side-by-side double-barrel configuration was necessary in the basilar artery. Without the PFED's resheathable capability, it would not have been possible to perform Y-stenting with flow diverters.

  12. Alteration of Basilar Artery Rho-Kinase and Soluble Guanylyl Cyclase Protein Expression in a Rat Model of Cerebral Vasospasm following Subarachnoid Hemorrhage

    Directory of Open Access Journals (Sweden)

    Chih-Jen Wang

    2014-01-01

    Full Text Available Background and Purpose. The vasoconstrictor endothelin-1 (ET-1 has been implicated in the pathogenesis of cerebral vasospasm following subarachnoid hemorrhage (SAH. Previous results showed that CGS 26303, an endothelin converting enzyme (ECE inhibitor, effectively prevented and reversed arterial narrowing in animal models of SAH. In the present study, we assessed the effect of CGS 26303 on neurological deficits in SAH rats. The involvement of vasoactive pathways downstream of ET-1 signaling in SAH was also investigated. Methods. Sprague-Dawley rats were divided into five groups (n=6/group: (1 normal control, (2 SAH, (3 SAH+vehicle, (4 SAH+CGS 26303 (prevention, and (5 SAH+CGS 26303 (reversal. SAH was induced by injecting autologous blood into cisterna magna. CGS 26303 (10 mg/kg was injected intravenously at 1 and 24 hr after the initiation of SAH in the prevention and reversal protocols, respectively. Behavioral changes were assessed at 48 hr after SAH. Protein expression was analyzed by Western blots. Results. Deficits in motor function were obvious in the SAH rats, and CGS 26303 significantly improved the rate of paraplegia. Expressions of rho-kinase-II and membrane-bound protein kinase C-δ and rhoA were significantly increased, while those of soluble guanylyl cyclase α1 and β1 as well as protein kinase G were significantly decreased in the basilar artery of SAH rats. Treatment with CGS 26303 nearly normalized these effects. Conclusions. These results demonstrate that the rhoA/rho-kinase and sGC/cGMP/PKG pathways play pivotal roles in cerebral vasospasm after SAH. It also shows that ECE inhibition is an effective strategy for the treatment of this disease.

  13. A new procedure for automatic fitting of the basilar-membrane input-output function to individual behavioral data

    DEFF Research Database (Denmark)

    Kowalewski, Borys; Fereczkowski, Michal; MacDonald, Ewen;

    2016-01-01

    system and, potentially, for clinical diagnostics. Computational algorithms are available that mimic the functioning of the nonlinear cochlear processing. One such algorithm is the dual resonance non-linear (DRNL) filterbank [6]. Its parameters can be modified to account for individual hearing loss, e...... parameters is difficult. Until recently, the parameters were manually adjusted and the fitting process was indirect. A new approach is described here, based on a search through a lookup table of pre-computed filterbank input-output functions. The aim of this approach is to provide a fast, stable, and more...

  14. Neuronal oscillations enhance stimulus discrimination by ensuring action potential precision

    DEFF Research Database (Denmark)

    Schaefer, Andreas T; Angelo, Kamilla; Spors, Hartwig

    2006-01-01

    Although oscillations in membrane potential are a prominent feature of sensory, motor, and cognitive function, their precise role in signal processing remains elusive. Here we show, using a combination of in vivo, in vitro, and theoretical approaches, that both synaptically and intrinsically gene......, membrane potential oscillations dramatically enhance the discriminatory capabilities of individual neurons and networks of cells and provide one attractive explanation for their abundance in neurophysiological systems....

  15. Hyperdense basilar artery sign diagnoses acute posterior circulation stroke and predicts short-term outcome

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Xiaoping [Affiliated Hospital of China Medical University at Shenyang, Department of Neurology, Shengjing Hospital, Shenyang (China); Guo, Yang [Shengjing Hospital, Department of Neurology, Shenyang (China)

    2010-12-15

    It is well established that the hyperdense middle cerebral artery sign is a specific marker for early ischemia in anterior circulation. However, little is known about the hyperdense basilar artery sign (HDBA) in posterior circulation. Our aim was to determine whether the HDBA sign has utility in early diagnosis of acute posterior circulation stroke and prediction of short-term outcome. Three-blinded readers examined unenhanced computed tomography scans for the HDBA sign, and materials were classified into two groups according to this sign. Vascular risk factors, admission and discharge National Institute of Health Stroke Scale (NIHSS) scores, short-term outcome, and radiological findings between the two groups were compared. One hundred and twenty-six cases of acute posterior circulation stroke (PCS) were included in the study. No statistically significant differences were found in risk factors of ischemic stroke, except atrial fibrillation (P = 0.025). Admission and discharge NIHSS scores for the positive HDBA group were significantly higher than scores for the negative HDBA group (P = 0.001, 0.002, respectively). The infarction territory for the positive HDBA group was mainly multi-region in nature (51.6%, P < 0.001), while the negative HDBA group showed mainly middle territory infarction. Significant independent predictors of short-term outcome included the HDBA sign (P < 0.001) and admission NIHSS scores (P < 0.001). Approximately half of the HDBA patients showed multi-region infarction and a serious neurological symptom. Based on our results, this sign might not only be helpful in early diagnosis of acute PCS but also be able to correlate with a poor short-term outcome. (orig.)

  16. Vertebro-basilar junction aneurysms: a single centre experience and meta-analysis of endovascular treatments.

    Science.gov (United States)

    Graziano, Francesca; Ganau, Mario; Iacopino, Domenico Gerardo; Boccardi, Edoardo

    2014-12-01

    Vascular lesions of the vertebrobasilar junction (VBJ) are challenging in neurosurgical practice, and their gold-standard therapy is still under debate. We describe the operative strategies currently in use for the management of these complex vascular lesions and discuss their rationale in a literature meta-analysis and single centre blinded retrospective study. The single centre study included a review of initial presentation, angiographic features and clinical outcome (with modified Rankin Scale [mRS] scores) over a long-term follow-up. In our series, small aneurysms were effectively treated by endosaccular coil embolization, whereas a strategy including flow-diverter devices combined with endosaccular coil embolization was the option of choice in large and giant aneurysms, leading to satisfactory outcomes in most cases. Our Medline review showed that endovascular treatment was chosen in most VBJ cases, whereas the microsurgical option was assigned to only a few cases. Among the endovascular treatments, the most common techniques used for the treatment of VBJ aneurysms were: coiling, stent-assisted coiling and flow diversion. Our study highlights that aneurysm morphology, location and patient-specific angio-architecture are key factors to be considered in the management of VBJ aneurysms. Most case series, including our own, show that parent artery reconstruction using a flow-diverter device is a feasible and successful technique in some cases of giant and complex aneurysms (especially those involving the lower third of the basilar artery) while a "sit back, wait and see" approach may represent the safest and most reasonable option.

  17. Potassium currents in auditory hair cells of the frog basilar papilla.

    Science.gov (United States)

    Smotherman, M S; Narins, P M

    1999-06-01

    The whole-cell patch-clamp technique was used to identify and characterize ionic currents in isolated hair cells of the leopard frog basilar papilla (BP). This end organ is responsible for encoding the upper limits of a frog's spectral sensitivity (1.25-2.0 kHz in the leopard frog). Isolated BP hair cells are the smallest hair cells in the frog auditory system, with spherical cell bodies typically less than 20 microm in diameter and exhibiting whole-cell capacitances of 4-7 pF. Hair cell zero-current resting potentials (Vz) varied around a mean of -65 mV. All hair cells possessed a non-inactivating, voltage-dependent calcium current (I(Ca)) that activates above a threshold of -55 mV. Similarly all hair cells possessed a rapidly activating, outward, calcium-dependent potassium current (I(K)(Ca)). Most hair cells also possessed a slowly activating, outward, voltage-dependent potassium current (I(K)), which is approximately 80% inactive at the hair cell Vz, and a fast-activating, inward-rectifying potassium current (I(K1)) which actively contributes to setting Vz. In a small subset of cells I(K) was replaced by a fast-inactivating, voltage-dependent potassium current (I(A)), which strongly resembled the A-current observed in hair cells of the frog sacculus and amphibian papilla. Most cells have very similar ionic currents, suggesting that the BP consists largely of one homogeneous population of hair cells. The kinetic properties of the ionic currents present (in particular the very slow I(K)) argue against electrical tuning, a specialized spectral filtering mechanism reported in the hair cells of birds, reptiles, and amphibians, as a contributor to frequency selectivity of this organ. Instead BP hair cells reflect a generalized strategy for the encoding of high-frequency auditory information in a primitive, mechanically tuned, terrestrial vertebrate auditory organ.

  18. Espasmo hemifacial e impressão basilar associados a malformação de arnold-chiari relato de caso

    OpenAIRE

    Manoel Baldoino Leal Filho; Elza Dias-Tosta; Nasser Allan; Paulo Said; José Luis F. Mendonça; Fernando Guilhon Henriques

    1992-01-01

    Os autores relatam o caso de uma paciente com espasmo hemifacial e impressão basilar associados a malformação de Arnold-Chiari. Com a descompressão cirúrgica da fossa posterior, empregada no tratamento da impressão basilar, houve melhora do quadro clínico e o espasmo hemifacial se reduziu quanto à frequência, duração e intensidade. É enfatizada a necessidade do tratamento etiológico do espasmo hemifacial, antes de se recorrer à toxina botulínica.

  19. Espasmo hemifacial e impressão basilar associados a malformação de arnold-chiari relato de caso

    Directory of Open Access Journals (Sweden)

    Manoel Baldoino Leal Filho

    1992-09-01

    Full Text Available Os autores relatam o caso de uma paciente com espasmo hemifacial e impressão basilar associados a malformação de Arnold-Chiari. Com a descompressão cirúrgica da fossa posterior, empregada no tratamento da impressão basilar, houve melhora do quadro clínico e o espasmo hemifacial se reduziu quanto à frequência, duração e intensidade. É enfatizada a necessidade do tratamento etiológico do espasmo hemifacial, antes de se recorrer à toxina botulínica.

  20. Sequential combination of two intravenous thrombolytics (recombinant tissue plasminogen activator/tenecteplase) in a patient with stroke and cardioembolic basilar artery occlusion.

    Science.gov (United States)

    Smadja, Didier; Olindo, Stéphane; Saint-Vil, Martine; Chausson, Nicolas

    2009-01-01

    Stroke caused by acute occlusion of basilar artery (AOBA) produces high risk of death. In eligible patients, thrombolysis significantly reduces mortality and disability rate. In most hospitals, thrombolysis is limited to intravenous (IV) route of recombinant tissue plasminogen activator, without any therapeutic alternative in cases of treatment failure. We report a case of cardioembolic AOBA, not responsive to a conventional regimen of IV recombinant tissue plasminogen activator. A sequential combination of IV tenecteplase (0.4 mg/kg) led to a complete recanalization of basilar artery, with a very good clinical outcome. The potential for a combination of two successive IV regimens should be evaluated in AOBA.

  1. Interaction of Glycolysis and Mitochondrial Respiration in Metabolic Oscillations of Pancreatic Islets

    DEFF Research Database (Denmark)

    Bertram, Richard; Satin, Leslie S.; Pedersen, Morten Gram

    2007-01-01

    Insulin secretion from pancreatic ß-cells is oscillatory, with a typical period of 2–7 min, reflecting oscillations in membrane potential and the cytosolic Ca2+ concentration. Our central hypothesis is that the slow 2–7 min oscillations are due to glycolytic oscillations, whereas faster oscillati...

  2. Phenomenology of neutrino oscillations

    Indian Academy of Sciences (India)

    G Rajasekaran

    2000-07-01

    The phenomenology of solar, atmospheric, supernova and laboratory neutrino oscillations is described. Analytical formulae for matter effects are reviewed. The results from oscillations are confronted with neutrinoless double beta decay.

  3. 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...

  4. Basilar Artery Territory Stroke Secondary to Invasive Fungal Sphenoid Sinusitis: A Case Report and Review of the Literature

    Directory of Open Access Journals (Sweden)

    Katherine A. Fu

    2015-03-01

    Full Text Available Background: Mucormycosis is a fungal infection with the following 5 classic forms: cutaneous, pulmonary, gastrointestinal, disseminated, and rhinocerebral. The rhinocerebral form can be rapidly progressive and invasive with a high mortality rate. We present a case of a 38-year-old man with invasive mucormycosis that led to a basilar artery territory stroke. Rhinocerebral mucormycosis is an unusual cause of stroke. Case Report: A 38-year-old man with a past medical history of diabetes mellitus presented with altered mental status. A lumbar puncture revealed eosinophilic pleocytosis with a mildly elevated total protein and borderline low glucose level. CT revealed a left medullary and cerebellar infarct confirmed by MRI. MRI also displayed a diffuse marrow signal abnormality in the clivus with contiguous sinus disease. Endoscopic sinus surgery confirmed that the fungal sinusitis was mucormycosis of the Rhizopus genus, which had affected the left sphenoid sinus, invaded through the skull base, and involved the basilar artery. He was given liposomal amphotericin (500 mg i.v. with posaconazole (400 mg i.v. twice daily. Due to the severity of the invasion and poor prognosis, the patient was discharged with comfort care measures. Discussion: Clinicians should be aware of invasive sinusitis as a rare cause of stroke in diabetics. Once the subarachnoid space and basal arteries of the brain have been invaded, the prognosis is very poor. The key to improvement of outcomes is early recognition and treatment, and examination of the sinuses on neuroimaging in all cases of stroke is vital.

  5. 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...

  6. Neutrino Masses and Oscillations

    CERN Document Server

    Valle, J W F

    2005-01-01

    I summarize the status of three--neutrino oscillations that follow from combining the relevant world's data. The discussion includes the small parameters Delta_m-sol/Delta_m-atm and \\sin^2\\theta_{13}, which characterize the strength of CP violation in neutrino oscillations, the impact of oscillation data on the prospects for probing the absolute scale of neutrino mass in \

  7. Neutrino oscillations: theory and phenomenology

    Energy Technology Data Exchange (ETDEWEB)

    Akhmedov, E.K., E-mail: akhmedov@ictp.trieste.it [Department of Theoretical Physics, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm (Sweden)

    2011-12-15

    A brief overview of selected topics in the theory and phenomenology of neutrino oscillations is given. These include: oscillations in vacuum and in matter; phenomenology of 3-flavour neutrino oscillations; CP and T violation in neutrino oscillations in vacuum and in matter; matter effects on {nu}{sub {mu}}{r_reversible}{nu}{sub {tau}} oscillations; parametric resonance in neutrino oscillations inside the earth; oscillations below and above the MSW resonance; unsettled issues in the theory of neutrino oscillations.

  8. Covariant harmonic oscillators and coupled harmonic oscillators

    Science.gov (United States)

    Han, Daesoo; Kim, Young S.; Noz, Marilyn E.

    1995-01-01

    It is shown that the system of two coupled harmonic oscillators shares the basic symmetry properties with the covariant harmonic oscillator formalism which provides a concise description of the basic features of relativistic hadronic features observed in high-energy laboratories. It is shown also that the coupled oscillator system has the SL(4,r) symmetry in classical mechanics, while the present formulation of quantum mechanics can accommodate only the Sp(4,r) portion of the SL(4,r) symmetry. The possible role of the SL(4,r) symmetry in quantum mechanics is discussed.

  9. [Cyclothymia and the brain stem. The question of symptomatic cyclothymia on the basis of observations in insufficiency of the basilar arterial system].

    Science.gov (United States)

    Marneros, A; Philipp, M

    1978-01-01

    Seven patients with an insufficiency in the basilar arterial system showed a typical endogenous depression. We assumed that the temporal coincidence of neurological and psychial syndromes was not accidental but both were caused by a circulation disturbance in the cerebral stem structures.

  10. Hypercapnic vasodilatation in isolated rat basilar arteries is exerted via low pH and does not involve nitric oxide synthase stimulation or cyclic GMP production

    DEFF Research Database (Denmark)

    You, J P; Wang, Qian; Zhang, W;

    1994-01-01

    The relaxant effect of hypercapnia (15% CO2) was studied in isolated circular segments of rat basilar arteries with intact endothelium. The nitric oxide synthase inhibitor nitro-L-arginine (L-NOARG) and the cytosolic guanylate cyclase inhibitor methylene blue (MB), significantly reduced...

  11. 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.

  12. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  13. 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.

  14. 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...

  15. Posterior fossa decompression with tonsillectomy in 104 cases of basilar impression, Chiari malformation and/or syringomyelia

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    2011-10-01

    Full Text Available The prime objective in the surgical treatment of basilar impression (BI, Chiari malformation (CM and/or syringomyelia (SM is based on the restoration of the normal cerebrospinal fluid (CSF dynamics at the craniovertebral junction through the creation of a large artificial cisterna magna. A small suboccipital craniectomy has been emphasized to avoid caudal migration of the hindbrain structures into the vertebral canal. Nevertheless, the results showed downward migration of the hindbrain related to that type of craniectomy. The authors present, otherwise, the results of 104 cases of BI, CM and/or SM, whose surgical treatment was characterized by a large craniectomy with the patient in the sitting position, tonsillectomy, large opening of the fourth ventricle and duraplasty with creation of a large artificial cisterna magna. A significant upward migration of the posterior fossa structures was detected by postoperative magnetic resonance imaging.

  16. Vanillin and vanillin analogs relax porcine coronary and basilar arteries by inhibiting L-type Ca2+ channels.

    Science.gov (United States)

    Raffai, Gábor; Khang, Gilson; Vanhoutte, Paul M

    2015-01-01

    Vanillin (VA) and vanillyl alcohol (VAA), components of natural vanilla, and ethyl vanillin (EtVA; synthetic analog) are used as flavoring agents and/or as additives by the food, cosmetic, or pharmaceutic industries. VA, VAA, and EtVA possess antioxidant and anti-inflammatory properties, but their vascular effects have not been determined. Therefore, we compared in isolated porcine coronary and basilar arteries the changes in isometric tension caused by VA, VAA, and EtVA. VA and its analogs caused concentration-dependent relaxations of both preparations during contractions from U46619 (9,11-dideoxy-11α,9α-epoxymethanoprostaglandin F2α, a thromboxane A2 receptor agonist), and of coronary arteries contracted with KCl or endothelin-1. The order of potency was VAA vanillin additives.

  17. Self-oscillation

    Science.gov (United States)

    Jenkins, Alejandro

    2013-04-01

    Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.

  18. Pressure oscillations in a chemical garden

    Science.gov (United States)

    Pantaleone, J.; Toth, A.; Horvath, D.; Rosefigura, L.; Morgan, W.; Maselko, J.

    2009-05-01

    When soluble metal salts are placed in a silicate solution, chemical gardens grow. These gardens are treelike structures formed of long thin hollow tubes. The growth is driven by the increase in internal pressure from osmosis. One particular case is examined here, calcium chloride in a solution of sodium trisilicate. We directly measure the internal pressure of a silicate garden as it grows via a series of relaxation oscillations. From these observations we deduce the stresses in the membrane and discuss how they influence the growth of tubes. Also we estimate the critical stress and the average Young’s modulus for the silicate garden’s membrane.

  19. Laser interferometry with translucent and absorbing mechanical oscillators

    CERN Document Server

    Friedrich, D; Westphal, T; Yamamoto, K; Sawadsky, A; Khalili, F Ya; Danilishin, S; Goßler, S; Danzmann, K; Schnabel, R

    2011-01-01

    The sensitivity of laser interferometers can be pushed into regimes that enable the direct observation of quantum behaviour of mechanical oscillators. In the past, membranes with subwavelength thickness (thin films) have been proposed as high-mechanical-quality, low-thermal-noise oscillators. Thin films from a homogenous material, however, generally show considerable light transmission accompanied by heating due to light absorption, which typically reduces the mechanical quality and limits quantum opto-mechanical experiments in particular at low temperatures. In this work, we experimentally analyze a Michelson-Sagnac interferometer including a translucent silicon nitride (SiN) membrane with subwavelength thickness. We find that such an interferometer provides an operational point being optimally suited for quantum opto-mechanical experiments with translucent oscillators. In case of a balanced beam splitter of the interferometer, the membrane can be placed at a node of the electro-magnetic field, which simulta...

  20. Convection and oscillations

    CERN Document Server

    Houdek, G

    2010-01-01

    In this short review on stellar convection dynamics I address the following, currently very topical, issues: (1) the surface effects of the Reynolds stresses and nonadiabaticity on solar-like pulsation frequencies, and (2) oscillation mode lifetimes of stochastically excited oscillations in red giants computed with different time-dependent convection formulations.

  1. Oscillations at low energies

    CERN Document Server

    Dwyer, D A

    2015-01-01

    A concise summary of the "Oscillation at low energies" parallel session at the 2014 Neutrino Oscillation Workshop is provided. Plans to use man-made neutrinos and antineutrinos to determine the neutrino mass hierarchy, search for sterile neutrinos, and to observe coherent neutrino-nucleus scattering were discussed. Potential measurements of solar neutrinos, supernova neutrinos, and geoneutrinos are also summarized.

  2. On the Dirac oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, R. de Lima [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Centro de Tecnologia. Unidade Academica de Educacao]. E-mail: rafael@df.ufcg.edu.br; rafaelr@cbpf.br

    2007-07-01

    In the present work we obtain a new representation for the Dirac oscillator based on the Clifford algebra C 7. The symmetry breaking and the energy eigenvalues for our model of the Dirac oscillator are studied in the non-relativistic limit. (author)

  3. Hyperchaotic Oscillator with Gyrators

    DEFF Research Database (Denmark)

    Tamasevicius, A; Cenys, A; Mykolaitis, G.;

    1997-01-01

    A fourth-order hyperchaotic oscillator is described. It contains a negative impedance converter, two gyratots, two capacitors and a diode. The dynamics of the oscillator is shown to be characterised by two positive Lyapunov exponents. The performance of the circuit is investigated by means...

  4. Disentangling neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, Andrew G. [Physics Department, Boston University, Boston, MA 02215 (United States)], E-mail: cohen@bu.edu; Glashow, Sheldon L. [Physics Department, Boston University, Boston, MA 02215 (United States)], E-mail: slg@bu.edu; Ligeti, Zoltan [Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)], E-mail: ligeti@lbl.gov

    2009-07-13

    The theory underlying neutrino oscillations has been described at length in the literature. The neutrino state produced by a weak decay is usually portrayed as a linear superposition of mass eigenstates with, variously, equal energies or equal momenta. We point out that such a description is incorrect, that in fact, the neutrino is entangled with the other particle or particles emerging from the decay. We offer an analysis of oscillation phenomena involving neutrinos (applying equally well to neutral mesons) that takes entanglement into account. Thereby we present a theoretically sound proof of the universal validity of the oscillation formulae ordinarily used. In so doing, we show that the departures from exponential decay reported by the GSI experiment cannot be attributed to neutrino mixing. Furthermore, we demonstrate that the 'Moessbauer' neutrino oscillation experiment proposed by Raghavan, while technically challenging, is correctly and unambiguously describable by means of the usual oscillation formalae.

  5. Nonlinear dynamics of self-oscillating polymer gels

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Self-oscillating polymer gels driven by Belousov-Zhabotinsky (BZ) chemical reaction are a new class of functional gels that have a wide range of potential applications (e.g., autonomously functioning membranes, actuate artificial muscles). However, the precise control of these gels has been an issue due to limited investigations of the influences of key system parameters on the characteristics of BZ gels. To address this deficiency, we studied the self-oscillating behavior of BZ gels using the nonline-ar dynamics theory and an Oregonator-like model, with focus placed upon the influences of various system parameters. The analysis of the oscillation phase indicated that the dynamic response of BZ gels represents the classical limit cycle oscillation. We then investigated the characteristics of the limit cycle oscillation and quantified the influences of key parameters (i.e., ini-tial reactant concentration, oxidation and reduction rate of catalyst, and response coefficient) on the self-oscillating behavior of BZ gels. The results demonstrated that sustained limit cycle oscillation of BZ gels can be achieved only when these key pa-rameters meet certain requirements, and that the pattern, period and amplitude of the oscillation are significantly influenced by these parameters. The results obtained in this study could enable the controlled self-oscillation of BZ gels system. This has several potential applications such as controlled drug delivery, miniature peristaltic pumps and microactuators.

  6. Enhancing hippocampal blood flow after cerebral ischemia and vasodilating basilar arteries: in vivo and in vitro neuroprotective effect of antihypertensive DDPH

    Directory of Open Access Journals (Sweden)

    Li Sun

    2015-01-01

    Full Text Available 1-(2,6-Dimethylphenoxy-2-(3,4-dimethoxyphenylethylamino-propane hydrochloride (DDPH is a novel antihypertensive agent based on structural characteristics of mexiletine and verapamine. We investigated the effect of DDPH on vasodilatation and neuroprotection in a rat model of cerebral ischemia in vivo, and a rabbit model of isolated basilar arteries in vitro. Our results show that DDPH (10 mg/kg significantly increased hippocampal blood flow in vivo in cerebral ischemic rats, and exerted dose-dependent relaxation of isolated basilar arteries contracted by histamine or KCl in the in vitro rabbit model. DDPH (3 × 10 -5 M also inhibited histamine-stimulated extracellular calcium influx and intracellular calcium release. Our findings suggest that DDPH has a vasodilative effect both in vivo and in vitro, which mediates a neuroprotective effect on ischemic nerve tissue.

  7. enhancing hippocampal blood lfow after cerebral ischemia and vasodilating basilar arteries:in vivo andin vitro neuroprotective effect of antihypertensive DDPH

    Institute of Scientific and Technical Information of China (English)

    Li Sun; Qin Li; Wei-ting Wang; Yu-hua Chen; Lian-jun Guo

    2015-01-01

    1-(2,6-Dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)-propane hydrochloride (DDPH) is a novel antihypertensive agent based on structural characteristics of mexiletine and verapamine. We investigated the effect of DDPH on vasodilatation and neuroprotection in a rat model of cerebral ischemiain vivo, and a rabbit model of isolated basilar arteriesin vitro. Our results show that DDPH (10 mg/kg) significantly increased hippocampal blood flowin vivo in cerebral ischemic rats, and exerted dose-dependent relaxation of isolated basilar arteries contracted by histamine or KCl in thein vitro rabbit model. DDPH (3 × 10–5 M) also inhibited histamine-stimulated extracellular calcium inlfux and intracellular calcium release. Our ifndings suggest that DDPH has a vasodilative effect bothin vivo andin vitro, which mediates a neuropro-tective effect on ischemic nerve tissue.

  8. Locked-in syndrome in a patient with acute obstructive hydrocephalus, caused by large unruptured aneurysm of the basilar artery (BA).

    Science.gov (United States)

    Kolić, Zlatko; Kukuljan, Melita; Vukas, Duje; Bonifačić, David; Vrbanec, Kristina; Franić, Ivana Karla

    2016-09-15

    We describe a case of acute obstructive hydrocephalus as a consequence of compression of the brainstem by a large aneurysm of the basilar artery (BA) in a 62-year-old male. After the insertion of the ventriculoperitoneal shunt (VPS), we encountered the "locked-in syndrome" clinical condition. "Locked-in syndrome" is a clinical state characterized by quadriplegia and anarthria with preserved consciousness, most commonly caused by ischemia in the ventral part of pons.

  9. Posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia

    Directory of Open Access Journals (Sweden)

    HU Peng

    2012-08-01

    Full Text Available Background Chiari malformation type Ⅰ(CM-Ⅰ is one of the soft tissue anomalies in craniovertebral junction (CVJ. This kind of soft tissue anomaly usually develops with bone anomaly, such as atlantoaxial subluxation, basilar invagination, platybasia, C1 assimilation, etc. For these complex combined anomalies, the treatment remains unaddressed. This study was performed to evaluate the effect of posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression for Chiari malformation type Ⅰ with basilar invagination, atlantoaxial subluxation, and syringomyelia. Methods Patients with basilar invagination and atlantoaxial subluxation treated from July 2004 to September 2011 were reviewed. Including criterions were made to screen matching patients. Including patients were retrospectively analyzed on both clinical outcomes and radiographical results. Japanese Orthopaedic Association (JOA score was used to evaluate the clinical outcomes, while the syrinx maximum size was measured on transverse view of MRI T2 image. The results were analyzed by SPSS 17.0 using t -text. Significant difference was considered when P ≤ 0.05. Results Fourteen patients met the including criterions, including 4 male patients and 10 female patients, with a mean age of 31.86 ± 11.36 (standard deviation, range: 17-51 years. Mean JOA score preoperatively of 14 patients was 13.07 ± 1.59 (standard deviation, while that was 15.57 ± 1.02 (standard deviation postoperatively (t = 9.946, P = 0.000. The mean syrinx size was (7.05 ± 1.98 mm (standard deviation, while that was (2.21 ± 1.91 mm (standard deviation postoperatively (t = 7.271, P = 0.000. There were no procedure-related morbidity or mortality happened. Conclusion Direct posterior reduction and internal fixation with posterior cranial fossa cranioectomy decompression can obviously improve the clinical outcomes and shrink syrinx for patients suffered from Chiari malformation typeⅠ with

  10. Ruptured aneurysm at the cortical segment of the distal posterior inferior cerebellar artery associated with hemodynamic stress after basilar artery occlusion

    Directory of Open Access Journals (Sweden)

    Akiko Marutani

    2016-01-01

    Conclusion: This report describes a case of de novo development of a saccular distal PICA aneurysm after atherosclerotic basilar artery occlusion. We believe that increased hemodynamic stress at the PICA might have contributed to the occurrence and rupture of the aneurysm. STA-SCA bypass, introduced in the territory of the cerebellar hemisphere, reduces hemodynamic stress, which would prevent the occurrence of de novo aneurysm and recurrent bleeding.

  11. Quasi-Fibonacci oscillators

    CERN Document Server

    Gavrilik, A M; Rebesh, A P

    2010-01-01

    We study the properties of sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p,q-oscillator, the 3-, 4- and 5-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consequtive energy levels satisfy the relation E_{n+1}=\\lambda E_n+\\rho E_{n-1} with real constants \\lambda, \\rho. On the other hand, for certain \\mu-oscillator known from 1993 we prove the fact of its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed among which for the \\mu$-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with non-constant, n-dependent coefficients \\lambda and \\rho. Various aspects of the QF relation are elaborated for the \\mu-oscillator and some of its extensions.

  12. Quasi-Fibonacci oscillators

    Science.gov (United States)

    Gavrilik, A. M.; Kachurik, I. I.; Rebesh, A. P.

    2010-06-01

    We study the properties of the sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p, q-oscillator, and the three-, four- and five-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consecutive energy levels satisfy the relation En + 1 = λEn + ρEn - 1 with real constants λ, ρ. On the other hand, for a certain μ-oscillator known since 1993, we prove its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed, among which for the μ-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with the non-constant, n-dependent coefficients λ and ρ. Various aspects of the QF relation are elaborated for the μ-oscillator and some of its extensions.

  13. Boxing with neutrino oscillations

    Science.gov (United States)

    Wagner, D. J.; Weiler, Thomas J.

    1999-06-01

    We develop a characterization of neutrino oscillations based on the coefficients of the oscillating terms. These coefficients are individually observable; although they are quartic in the elements of the unitary mixing matrix, they are independent of the conventions chosen for the angle and phase parametrization of the mixing matrix. We call these reparametrization-invariant observables ``boxes'' because of their geometric relation to the mixing matrix, and because of their association with the Feynman box diagram that describes oscillations in field theory. The real parts of the boxes are the coefficients for the CP- or T-even oscillation modes, while the imaginary parts are the coefficients for the CP- or T-odd oscillation modes. Oscillation probabilities are linear in the boxes, so measurements can straightforwardly determine values for the boxes (which can then be manipulated to yield magnitudes of mixing matrix elements). We examine the effects of unitarity on the boxes and discuss the reduction of the number of boxes to a minimum basis set. For the three-generation case, we explicitly construct the basis. Using the box algebra, we show that CP violation may be inferred from measurements of neutrino flavor mixing even when the oscillatory factors have averaged. The framework presented here will facilitate general analyses of neutrino oscillations among n>=3 flavors.

  14. Combined extracranial-intracranial bypass surgery with stent-assisted coil embolization for moyamoya disease with a ruptured wide-necked basilar trunk aneurysm: a case report.

    Science.gov (United States)

    Jiang, Hanqiang; Ni, Wei; Lei, Yu; Li, Yanjiang; Gu, Yuxiang

    2015-01-01

    A ruptured wide-necked basilar trunk aneurysm is uncommon in patients with moyamoya disease. The optimal treatment is unclear. We report a safe and beneficial treatment modality for moyamoya disease with aneurysms located in the posterior circulation. A 37-year-old man presenting with subarachnoid hemorrhage was admitted to our hospital. Emergent cerebral angiography demonstrated moyamoya disease associated with a wide-necked basilar trunk aneurysm. We performed bilateral extracranial-intracranial bypass surgeries prior to stent-assisted coil embolization of the aneurysm after the acute phase. No complication occurred and the patient was discharged with no neurological deficit. Follow-up digital subtraction angiography (DSA) performed 6 months after the surgery showed that all the anastomosises were patent and bilateral collateral vascular compensation was fully established with no recanalization of the basilar trunk aneurysm post embolization.We also found that high-flow bypass did not contribute to cerebral revascularization as imagined despite the good patency. Combined extracranial-intracranial bypass surgery with endovascular treatment proved to be an efficient therapeutic modality for moyamoya disease with aneurysms located in the posterior circulation. High-flow bypass surgery was not essential due to the inefficiency and the high risk of postoperative cerebral hyperperfusion syndrome.

  15. 基底动脉发育不良影像学特征%Imaging characteristics of basilar artery hypoplasia

    Institute of Scientific and Technical Information of China (English)

    顾华; 钱晓军; 王双坤; 闵小红; 鲁万红; 胡文立

    2014-01-01

    目的 研究基底动脉发育不良(BAH)的影像学特征.方法 回顾2009年10月至2013年8月在首都医科大学附属北京朝阳医院进行MRA和MRI检查的连续病例.根据BAH诊断标准共检出210例BAH,测量(椎)基底动脉直径.根据诊断标准急性脑梗死分成前循环和后循环梗死.结果 10 193例MRA中检出210例BAH,女性多于男性.BAH伴有双侧胚胎型大脑后动脉175例(83.3%),单侧35例(16.7%).99.5% BAH患者伴有V4段椎动脉发育不良;颈段(V1 ~V3)椎动脉发育不良占56.0%(28/50).210例中74例合并急性脑梗死,男性多于女性(59.5%比40.5%,P=0.021).急性脑梗死中BAH的发病率是2.2%(74/3 294).结论 BAH是较少见的脑血管发育异常,伴有胚胎型大脑后动脉和V4段椎动脉发育不良.%Objective To determine the imaging characteristics of basilar artery hypoplasia (BAH).Methods From October 2009 to August 2013,10 193 magnetic resonance angiogram (MRA) and 31 716 magnetic resonance imaging (MRI) consecutive cases were retrospectively retrieved from our institutional Picture Archiving and Communication System (PACS) database.BAH was defined as a continuous diameter reduction all over artery and a basilar artery diameter ≤2 mm.The same cut-off value was applied for vertebral artery hypoplasia (VAH).We measured the diameters of basilar and vertebral arteries with PACS in all patients according to source imaging and IMP construction of MRA.The carotid arterial computed tomography angiogram (CTA) profiles were reviewed in 50 patients.The fetal-type posterior circle of Willis (FTP) was assessed.The diagnosis of acute cerebral infarction was based on clinical symptoms,signs and a high signal on diffusion-weighted imaging (DWI).Acute cerebral infarction was divided into anterior circulation stroke (ACS) and posterior circulation stroke (PCS).Results A total of 210 BAH were identified among 10 193 consecutive patients.BAH was more common in females (56.7%) than males

  16. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  17. Biobased Membrane

    NARCIS (Netherlands)

    Koenders, E.A.B.; Zlopasa, J.; Picken, S.J.

    2015-01-01

    The present invention is in the field of a composition for forming a bio-compatible membrane applicable to building material, such as concrete, cement, etc., to a meth od of applying said composition for forming a bio-compatible membrane, a biocompatible membrane, use of said membrane for various pu

  18. Oscillating Filaments: I - Oscillation and Geometrical Fragmentation

    CERN Document Server

    Gritschneder, Matthias; Burkert, Andreas

    2016-01-01

    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, e.g. 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 characteristical 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. ...

  19. High frequency nanotube oscillator

    Science.gov (United States)

    Peng, Haibing; Zettl, Alexander K.

    2012-02-21

    A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.

  20. Synchronization of hyperchaotic oscillators

    DEFF Research Database (Denmark)

    Tamasevicius, A.; Cenys, A.; Mykolaitis, G.;

    1997-01-01

    Synchronization of chaotic oscillators is believed to have promising applications in secure communications. Hyperchaotic systems with multiple positive Lyapunov exponents (LEs) have an advantage over common chaotic systems with only one positive LE. Three different types of hyperchaotic electronic...

  1. A novel photonic oscillator

    Science.gov (United States)

    Yao, X. S.; Maleki, L.

    1995-01-01

    We report a novel oscillator for photonic RF systems. This oscillator is capable of generating high-frequency signals up to 70 GHz in both electrical and optical domains and is a special voltage-controlled oscillator with an optical output port. It can be used to make a phase-locked loop (PLL) and perform all functions that a PLL is capable of for photonic systems. It can be synchronized to a reference source by means of optical injection locking, electrical injection locking, and PLL. It can also be self-phase locked and self-injection locked to generate a high-stability photonic RF reference. Its applications include high-frequency reference regeneration and distribution, high-gain frequency multiplication, comb-frequecy and square-wave generation, carrier recovery, and clock recovery. We anticipate that such photonic voltage-controlled oscillators (VCOs) will be as important to photonic RF systems as electrical VCOs are to electrical RF systems.

  2. Neural Oscillators Programming Simplified

    Directory of Open Access Journals (Sweden)

    Patrick McDowell

    2012-01-01

    Full Text Available The neurological mechanism used for generating rhythmic patterns for functions such as swallowing, walking, and chewing has been modeled computationally by the neural oscillator. It has been widely studied by biologists to model various aspects of organisms and by computer scientists and robotics engineers as a method for controlling and coordinating the gaits of walking robots. Although there has been significant study in this area, it is difficult to find basic guidelines for programming neural oscillators. In this paper, the authors approach neural oscillators from a programmer’s point of view, providing background and examples for developing neural oscillators to generate rhythmic patterns that can be used in biological modeling and robotics applications.

  3. Neutrino anomalies without oscillations

    Indian Academy of Sciences (India)

    Sandip Pakvasa

    2000-01-01

    I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the `conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.

  4. Oscillations in counting statistics

    CERN Document Server

    Wilk, Grzegorz

    2016-01-01

    The very large transverse momenta and large multiplicities available in present LHC experiments on pp collisions allow a much closer look at the corresponding distributions. Some time ago we discussed a possible physical meaning of apparent log-periodic oscillations showing up in p_T distributions (suggesting that the exponent of the observed power-like behavior is complex). In this talk we concentrate on another example of oscillations, this time connected with multiplicity distributions P(N). We argue that some combinations of the experimentally measured values of P(N) (satisfying the recurrence relations used in the description of cascade-stochastic processes in quantum optics) exhibit distinct oscillatory behavior, not observed in the usual Negative Binomial Distributions used to fit data. These oscillations provide yet another example of oscillations seen in counting statistics in many different, apparently very disparate branches of physics further demonstrating the universality of this phenomenon.

  5. Oscillating Filaments. I. Oscillation and Geometrical Fragmentation

    Science.gov (United States)

    Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas

    2017-01-01

    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.

  6. The Liege Oscillation Code

    CERN Document Server

    Scuflaire, R; Théado, S; Bourge, P -O; Miglio, A; Godart, M; Thoul, A; Noels, A

    2007-01-01

    The Liege Oscillation code can be used as a stand-alone program or as a library of subroutines that the user calls from a Fortran main program of his own to compute radial and non-radial adiabatic oscillations of stellar models. We describe the variables and the equations used by the program and the methods used to solve them. A brief account is given of the use and the output of the program.

  7. Ultrastable Multigigahertz Photonic Oscillator

    Science.gov (United States)

    Logan, Ronald T., Jr.

    1996-01-01

    Novel photonic oscillator developed to serve as ultrastable source of microwave and millimeter-wave signals. In system, oscillations generated photonically, then converted to electronic form. Includes self-mode-locked semiconductor laser producing stream of pulses, detected and fed back to laser as input. System also includes fiber-optic-delay-line discriminator, which detects fluctuations of self-mode-locking frequency and generates error signal used in negative-feedback loop to stabilize pulse-repetition frequency.

  8. Indirect neutrino oscillations

    CERN Document Server

    Babu, K S; Wilczek, Frank; Pati, Jogesh C; Wilczek, Frank

    1995-01-01

    We show how two different scales for oscillations between e and \\mu neutrinos, characterized by different mixing angles and effective mass scales, can arise in a simple and theoretically attractive framework. One scale characterizes direct oscillations, which can accommodate the MSW approach to the solar neutrino problem, whereas the other can be considered as arising indirectly, through virtual transitions involving the \\tau neutrino with a mass \\sim 1 eV. This indirect transition allows the possibility of observable \\bar \

  9. Oscillators and operational amplifiers

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2005-01-01

    A generalized approach to the design of oscillators using operational amplifiers as active elements is presented. A piecewise-linear model of the amplifier is used so that it make sense to investigate the eigenvalues of the Jacobian of the differential equations. The characteristic equation...... of the general circuit is derived. The dynamic nonlinear transfer characteristic of the amplifier is investigated. Examples of negative resistance oscillators are discussed....

  10. Self-oscillation

    CERN Document Server

    Jenkins, Alejandro

    2011-01-01

    Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain linear systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy from the environment into the vibration: no external rate needs to be tuned to the resonant frequency. A paper from 1830 by G. B. Airy gives us the opening to introduce self-oscillation as a sort of "perpetual motion" responsible for the human voice. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the more recent swaying of the London Millenium Footbridge. Clocks are self-oscillators, as are bowed and wind musical instruments, and the heartbeat. We review the criterion that determines whether an arbitrary line...

  11. The impact of cortical deafferentation on the neocortical slow oscillation.

    Science.gov (United States)

    Lemieux, Maxime; Chen, Jen-Yung; Lonjers, Peter; Bazhenov, Maxim; Timofeev, Igor

    2014-04-16

    Slow oscillation is the main brain rhythm observed during deep sleep in mammals. Although several studies have demonstrated its neocortical origin, the extent of the thalamic contribution is still a matter of discussion. Using electrophysiological recordings in vivo on cats and computational modeling, we found that the local thalamic inactivation or the complete isolation of the neocortical slabs maintained within the brain dramatically reduced the expression of slow and fast oscillations in affected cortical areas. The slow oscillation began to recover 12 h after thalamic inactivation. The slow oscillation, but not faster activities, nearly recovered after 30 h and persisted for weeks in the isolated slabs. We also observed an increase of the membrane potential fluctuations recorded in vivo several hours after thalamic inactivation. Mimicking this enhancement in a network computational model with an increased postsynaptic activity of long-range intracortical afferents or scaling K(+) leak current, but not several other Na(+) and K(+) intrinsic currents was sufficient for recovering the slow oscillation. We conclude that, in the intact brain, the thalamus contributes to the generation of cortical active states of the slow oscillation and mediates its large-scale synchronization. Our study also suggests that the deafferentation-induced alterations of the sleep slow oscillation can be counteracted by compensatory intracortical mechanisms and that the sleep slow oscillation is a fundamental and intrinsic state of the neocortex.

  12. Frequency of self-oscillations

    CERN Document Server

    Groszkowski, Janusz

    2013-01-01

    Frequency of Self-Oscillations covers the realm of electric oscillations that plays an important role both in the scientific and technical aspects. This book is composed of nine chapters, and begins with the introduction to the alternating currents and oscillation. The succeeding chapters deal with the free oscillations in linear isolated systems. These topics are followed by discussions on self-oscillations in linear systems. Other chapters describe the self-oscillations in non-linear systems, the influence of linear elements on frequency of oscillations, and the electro mechanical oscillato

  13. Endovascular Treatment of the Huge Dissecting Aneurysms Involving the Basilar Artery by the Internal Trapping Technique: Technical Note

    Institute of Scientific and Technical Information of China (English)

    Shi-Qing Mu; Xin-Jian Yang; You-Xiang Li; Chu-Han Jiang; Zhong-Xue Wu

    2015-01-01

    Background:The endovascular strategy of the huge dissecting aneurysms involving the basilar artery (BA) is controversial and challenging.This study was to investigate the clinical and angiographic outcomes of the treatment of the huge dissecting aneurysms involving the BA by the internal trapping (IT) technique.Methods:We retrospectively studied 15 patients with the huge dissecting aneurysms involving the BA treated by the IT technique between September 2005 and September 2014 in Department of lnterventional Neuroradiology of Beijing Tiantan Hospital.Clinical and angiographic data were reviewed and evaluated.Results:All patients were treated by the IT technique.That meant the dissecting artery and aneurysm segments were completed occlusion.After the procedure,the angiography demonstrated that all the dissecting artery and aneurysm segments were completed occlusion.Follow-up angiography was performed at 3-6 months or 12-18 months after the endovascular treatment (median 8 months),14 patients had a good recovery.Re-canalization occurred in one patient whose aneurysm involved in bilateral vertebral arteries and the two third of the middle-lower BA.After the second treatment,the patient died by the ventricular tachycardia.Conclusions:The IT technique is a technically feasible and safe alternative for the treatment of BA dissecting aneurysms,but it is not necessarily the safest or most definitive treatment modality.The ideal treatment of the huge dissecting aneurysms involving the BA remains debatable and must be investigated on a case-by-case basis.

  14. Endovascular Treatment of the Huge Dissecting Aneurysms Involving the Basilar Artery by the Internal Trapping Technique: Technical Note

    Directory of Open Access Journals (Sweden)

    Shi-Qing Mu

    2015-01-01

    Full Text Available Background: The endovascular strategy of the huge dissecting aneurysms involving the basilar artery (BA is controversial and challenging. This study was to investigate the clinical and angiographic outcomes of the treatment of the huge dissecting aneurysms involving the BA by the internal trapping (IT technique. Methods: We retrospectively studied 15 patients with the huge dissecting aneurysms involving the BA treated by the IT technique between September 2005 and September 2014 in Department of Interventional Neuroradiology of Beijing Tiantan Hospital. Clinical and angiographic data were reviewed and evaluated. Results: All patients were treated by the IT technique. That meant the dissecting artery and aneurysm segments were completed occlusion. After the procedure, the angiography demonstrated that all the dissecting artery and aneurysm segments were completed occlusion. Follow-up angiography was performed at 3-6 months or 12-18 months after the endovascular treatment (median 8 months, 14 patients had a good recovery. Re-canalization occurred in one patient whose aneurysm involved in bilateral vertebral arteries and the two third of the middle-lower BA. After the second treatment, the patient died by the ventricular tachycardia. Conclusions: The IT technique is a technically feasible and safe alternative for the treatment of BA dissecting aneurysms, but it is not necessarily the safest or most definitive treatment modality. The ideal treatment of the huge dissecting aneurysms involving the BA remains debatable and must be investigated on a case-by-case basis.

  15. Evaluation of the Effects of Sildenafil Citrate (Viagra) on Vertebral Artery Blood Flow in Patients with Vertebro-Basilar Insufficiency

    Energy Technology Data Exchange (ETDEWEB)

    Bozgeyik, Zulkif; Berilgen, Sait; Ozdemir, Huseyin; Ogur, Erkin [Firat University School of Medicine, Elazig(Turkmenistan); Tekatas, Aslan [Elazig Government Hospital, Elazig (Turkmenistan)

    2008-12-15

    To investigate the effects of sildenafil citrate (Viagra) on the vertebral artery blood flow of patients with vertebro-basilar insufficiency (VBI) using color duplex sonography (CDS). The study included 21 patients with VBI (aged 31-76; mean 61.0 +- 10.5 yrs). We administered a 50 mg oral dose of sildenafil citrate to all patients. Next, we measured the peak systolic velocity (Vmax), end diastolic velocity (Vmin), resistive index (RI), pulsatility index (PI), diameter, area, and flow volume (FV) of vertebral arteries using CDS before the administration of sildenafil citrate; 45 minutes after, and 75 minutes after administration. Statistical testing was performed using SPSS for windows version 11.0. The statistical test used to determine the outcome of the analysis was the repeated measures analysis of variance (ANOVA) test. Compared to the baseline values, the vertebral artery diameter, area, and FV increased significantly following the administration of sildenafil citrate. The diameter, area and FV increased from 3.39 mm at 45 minutes to 3.64 mm at 75 minutes, 9.43 cm{sup 2} to 10.80 cm{sup 2} at 45 minutes and 10.81 cm{sup 2} at 75 minutes, as well as from 0.07 L/min at baseline to 0.09 L/min at 45 minutes and unchanged at 75 minutes, respectively. Sildenafil citrate elicited a significant effect on vertebral artery diameter, area and FVs

  16. Membranous nephropathy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000472.htm Membranous nephropathy To use the sharing features on this page, please enable JavaScript. Membranous nephropathy is a kidney disorder that leads to changes ...

  17. Oscillations in stellar superflares

    CERN Document Server

    Balona, L A; Kosovichev, A; Nakariakov, V M; Pugh, C E; Van Doorsselaere, T

    2015-01-01

    Two different mechanisms may act to induce quasi-periodic pulsations (QPP) in whole-disk observations of stellar flares. One mechanism may be magneto-hydromagnetic (MHD) forces and other processes acting on flare loops as seen in the Sun. The other mechanism may be forced local acoustic oscillations due to the high-energy particle impulse generated by the flare (known as `sunquakes' in the Sun). We analyze short-cadence Kepler data of 257 flares in 75 stars to search for QPP in the flare decay branch or post-flare oscillations which may be attributed to either of these two mechanisms. About 18 percent of stellar flares show a distinct bump in the flare decay branch of unknown origin. The bump does not seem to be a highly-damped global oscillation because the periods of the bumps derived from wavelet analysis do not correlate with any stellar parameter. We detected damped oscillations covering several cycles (QPP), in seven flares on five stars. The periods of these oscillations also do not correlate with any ...

  18. Oscillations following periodic reinforcement.

    Science.gov (United States)

    Monteiro, Tiago; Machado, Armando

    2009-06-01

    Three experiments examined behavior in extinction following periodic reinforcement. During the first phase of Experiment 1, four groups of pigeons were exposed to fixed interval (FI 16s or FI 48s) or variable interval (VI 16s or VI 48s) reinforcement schedules. Next, during the second phase, each session started with reinforcement trials and ended with an extinction segment. Experiment 2 was similar except that the extinction segment was considerably longer. Experiment 3 replaced the FI schedules with a peak procedure, with FI trials interspersed with non-food peak interval (PI) trials that were four times longer. One group of pigeons was exposed to FI 20s PI 80s trials, and another to FI 40s PI 160s trials. Results showed that, during the extinction segment, most pigeons trained with FI schedules, but not with VI schedules, displayed pause-peck oscillations with a period close to, but slightly greater than the FI parameter. These oscillations did not start immediately after the onset of extinction. Comparing the oscillations from Experiments 1 and 2 suggested that the alternation of reconditioning and re-extinction increases the reliability and earlier onset of the oscillations. In Experiment 3 the pigeons exhibited well-defined pause-peck cycles since the onset of extinction. These cycles had periods close to twice the value of the FI and lasted for long intervals of time. We discuss some hypotheses concerning the processes underlying behavioral oscillations following periodic reinforcement.

  19. Oscillate boiling from microheaters

    Science.gov (United States)

    Li, Fenfang; Gonzalez-Avila, S. Roberto; Nguyen, Dang Minh; Ohl, Claus-Dieter

    2017-01-01

    We report about an intriguing boiling regime occurring for small heaters embedded on the boundary in subcooled water. The microheater is realized by focusing a continuous wave laser beam to about 10 μ m in diameter onto a 165-nm-thick layer of gold, which is submerged in water. After an initial vaporous explosion a single bubble oscillates continuously and repeatedly at several 100 kHz albeit with constant laser power input. The microbubble's oscillations are accompanied with bubble pinch-off, leading to a stream of gaseous bubbles in the subcooled water. The self-driven bubble oscillation is explained with a thermally kicked oscillator caused by surface attachment and by the nonspherical collapses. Additionally, Marangoni stresses induce a recirculating streaming flow which transports cold liquid towards the microheater, reducing diffusion of heat along the substrate and therefore stabilizing the phenomenon to many million cycles. We speculate that this oscillate boiling regime may overcome the heat transfer thresholds observed during the nucleate boiling crisis and offers a new pathway for heat transfer under microgravity conditions.

  20. Finite q-oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Atakishiyev, Natig M [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Klimyk, Anatoliy U [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Wolf, Kurt Bernardo [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)

    2004-05-28

    The finite q-oscillator is a model that obeys the dynamics of the harmonic oscillator, with the operators of position, momentum and Hamiltonian being functions of elements of the q-algebra su{sub q}(2). The spectrum of position in this discrete system, in a fixed representation j, consists of 2j + 1 'sensor'-points x{sub s} = 1/2 [2s]{sub q}, s element of {l_brace}-j, -j+1, ..., j{r_brace}, and similarly for the momentum observable. The spectrum of energies is finite and equally spaced, so the system supports coherent states. The wavefunctions involve dual q-Kravchuk polynomials, which are solutions to a finite-difference Schroedinger equation. Time evolution (times a phase) defines the fractional Fourier-q-Kravchuk transform. In the classical limit as q {yields} 1 we recover the finite oscillator Lie algebra, the N = 2j {yields} {infinity} limit returns the Macfarlane-Biedenharn q-oscillator and both limits contract the generators to the standard quantum-mechanical harmonic oscillator.

  1. Finite q-oscillator

    Science.gov (United States)

    Atakishiyev, Natig M.; Klimyk, Anatoliy U.; Wolf, Kurt Bernardo

    2004-05-01

    The finite q-oscillator is a model that obeys the dynamics of the harmonic oscillator, with the operators of position, momentum and Hamiltonian being functions of elements of the q-algebra suq(2). The spectrum of position in this discrete system, in a fixed representation j, consists of 2j + 1 'sensor'-points x_s={\\case12}[2s]_q, s\\in\\{-j,-j+1,\\ldots,j\\} , and similarly for the momentum observable. The spectrum of energies is finite and equally spaced, so the system supports coherent states. The wavefunctions involve dual q-Kravchuk polynomials, which are solutions to a finite-difference Schrödinger equation. Time evolution (times a phase) defines the fractional Fourier-q-Kravchuk transform. In the classical limit as q rarr 1 we recover the finite oscillator Lie algebra, the N = 2j rarr infin limit returns the Macfarlane-Biedenharn q-oscillator and both limits contract the generators to the standard quantum-mechanical harmonic oscillator.

  2. Firing membranes

    NARCIS (Netherlands)

    Kappert, Emiel Jan

    2015-01-01

    Thermal processing is commonly employed to alter the chemistry and microstructure of membrane layers. It can shape, strengthen, and give functionality to a membrane. A good understanding of the processes taking place during the thermal processing of a membrane material allows for optimization and tu

  3. Basilar impression, Chiari malformation and syringomyelia: a retrospective study of 53 surgically treated patients Impressão basilar, malformação de Chiari e siringomielia: estudo retrospecivo de 53 casos operados

    Directory of Open Access Journals (Sweden)

    José Alberto Gonçalves da Silva

    2003-06-01

    Full Text Available The present study shows the results of 53 patients who have been treated surgically for basilar impression (BI, Chiari malformation (CM, and syringomyelia (SM. The patients were divided into two groups. Group I (24 patients underwent osteodural decompression with large inferior occipital craniectomy, laminectomy from C 1 to C 3, dural opening in Y format, dissection of arachnoid adhesion between the cerebellar tonsils, medulla oblongata and spinal cord, large opening of the fourth ventricle and dural grafting with the use of bovine pericardium. Group II patients (29 patients underwent osteodural-neural decompression with the same procedures described above plus dissection of the arachnoid adherences of the vessels of the region of the cerebellar tonsils, and tonsillectomy (amputation in 10 cases, and as for the remainning 19 cases, intrapial aspiration of the cerebellar tonsils was performed. The residual pial sac was sutured to the dura in craniolateral position. After completion of the suture of the dural grafting, a thread was run through the graft at the level of the created cisterna magna and fixed to the cervical aponeurosis so as to move the dural graft on a posterior- caudal direction, avoiding, in this way, its adherence to the cerebellum.São analisados os resultados obtidos com o tratamento cirúrgico de 53 casos de impressão basilar (IB, malformação de Chiari (MC e siringomielia (SM. Os pacientes foram divididos em dois grupos: no grupo I (24 casos foi realizada a descompressão osteodural, caracterizada por craniectomia ampla occipital inferior, laminectomia variável de C 1 a C 3, abertura da dura-máter em forma de Y, dissecção das aderências aracnóideas das tonsilas cerebelares com o bulbo e medula cervical, abertura ampla do quarto ventrículo e enxerto dural; no grupo II (29 casos foi utilizada a descompressão osteodural-neural, caracterizada pelos mesmos detalhes técnicos empregados no grupo I, acrescidos da

  4. Arbitrary Spin Galilean Oscillator

    CERN Document Server

    Hagen, C R

    2014-01-01

    The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be extended successfully to the arbitrary spin S case primarily because of the unwieldiness of general spin Lorentz invariant wave equations. It is shown here using the formalism of totally symmetric multispinors that the Dirac oscillator can, however, be made to accommodate spin by incorporating it into the framework of Galilean relativity. This is done explicitly for spin zero and spin one as special cases of the arbitrary spin result. For the general case it is shown that the coefficient of the spin-orbit term has a 1/S behavior by techniques which are virtually identical to those employed in the derivation of the g-factor carried out over four decades ago.

  5. Oscillations in neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Hoeye, Gudrun Kristine

    1999-07-01

    We have studied radial and nonradial oscillations in neutron stars, both in a general relativistic and non-relativistic frame, for several different equilibrium models. Different equations of state were combined, and our results show that it is possible to distinguish between the models based on their oscillation periods. We have particularly focused on the p-, f-, and g-modes. We find oscillation periods of II approx. 0.1 ms for the p-modes, II approx. 0.1 - 0.8 ms for the f-modes and II approx. 10 - 400 ms for the g-modes. For high-order (l (>{sub )} 4) f-modes we were also able to derive a formula that determines II{sub l+1} from II{sub l} and II{sub l-1} to an accuracy of 0.1%. Further, for the radial f-mode we find that the oscillation period goes to infinity as the maximum mass of the star is approached. Both p-, f-, and g-modes are sensitive to changes in the central baryon number density n{sub c}, while the g-modes are also sensitive to variations in the surface temperature. The g-modes are concentrated in the surface layer, while p- and f-modes can be found in all parts of the star. The effects of general relativity were studied, and we find that these are important at high central baryon number densities, especially for the p- and f-modes. General relativistic effects can therefore not be neglected when studying oscillations in neutron stars. We have further developed an improved Cowling approximation in the non-relativistic frame, which eliminates about half of the gap in the oscillation periods that results from use of the ordinary Cowling approximation. We suggest to develop an improved Cowling approximation also in the general relativistic frame. (Author)

  6. Solar-neutrino oscillations

    Science.gov (United States)

    Krauss, L.; Wilczek, F.

    1985-01-01

    The theory of oscillations of solar neutrinos is developed as it applies to the electron-recoil spectrum in neutrino-electron scattering. The spectral information obtained by such measurements (as opposed to counting total event rates) is crucial for allowing observation of neutrino oscillations for masses down to 500 neV. In this regard, the effects of different masses and mixing angles, as well as such subtleties as thermal and pressure broadening, finite solar-core size, and variable indices of refraction are investigated.

  7. Friedel oscillations in graphene

    DEFF Research Database (Denmark)

    Lawlor, J. A.; Power, S. R.; Ferreira, M.S.

    2013-01-01

    Symmetry breaking perturbations in an electronically conducting medium are known to produce Friedel oscillations in various physical quantities of an otherwise pristine material. Here we show in a mathematically transparent fashion that Friedel oscillations in graphene have a strong sublattice...... asymmetry. As a result, the presence of impurities and/or defects may impact the distinct graphene sublattices very differently. Furthermore, such an asymmetry can be used to explain the recent observations that nitrogen atoms and dimers are not randomly distributed in graphene but prefer to occupy one...

  8. Nonlinear harmonic oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Calogero, F [Dipartimento di Fisica, Universita di Roma ' La Sapienza' (Italy); Inozemtsev, V I [Joint Institute for Nuclear Research, Dubna (Russian Federation)

    2002-12-06

    The existence is noted of assemblies of an arbitrary number of complex oscillators, or equivalently, of an arbitrary even number of real oscillators, characterized by Newtonian equations of motion ('acceleration equal force') with one-body velocity-dependent linear forces and many-body velocity-independent cubic forces, all the nonsingular solutions of which are isochronous (completely periodic with the same period). As for the singular solutions, as usual they emerge, in the context of the initial-value problem, from a closed domain in phase space having lower dimensionality.

  9. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

    Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

  10. 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).

  11. Biological oscillations: Fluorescence monitoring by confocal microscopy

    Science.gov (United States)

    Chattoraj, Shyamtanu; Bhattacharyya, Kankan

    2016-09-01

    Fluctuations play a vital role in biological systems. Single molecule spectroscopy has recently revealed many new kinds of fluctuations in biological molecules. In this account, we focus on structural fluctuations of an antigen-antibody complex, conformational dynamics of a DNA quadruplex, effects of taxol on dynamics of microtubules, intermittent red-ox oscillations at different organelles in a live cell (mitochondria, lipid droplets, endoplasmic reticulum and cell membrane) and stochastic resonance in gene silencing. We show that there are major differences in these dynamics between a cancer cell and the corresponding non-cancer cell.

  12. Valor da linha bimastóidea de Fischgold e Metzger para o diagnóstico radiológico da impressão basilar

    Directory of Open Access Journals (Sweden)

    Horacio M. Canelas

    1956-12-01

    Full Text Available No sentido de precisar os valores normais da distância entre o ápice da apófise odontóide do áxis e a linha bimastóidea de Fischgold e Metzger - índice valioso para o diagnóstico radiológico de impressão basilar - os autores fazem o estudo estatístico das medidas realizadas em 127 craniogramas de pacientes sem malformações occípito-cervicais e em 11 casos de impressão basilar diagnosticada clínica e radiològicamente. São estudadas as correlações dessa distância com a idade e com a distância entre a ponta da odontóide e a linha basal de McGregor. Os autores concluem que: 1 Acima de 10 anos de idade, a média da distância entre a ponta odontóidea e a linha de Fischgold e Metzger é, normalmente, de +0,56 ± 5,79 mm, à qual correspondem os limites fiduciais de -10,79 e +11,91 mm. Logo, valores dessa distância superiores a 12 mm devem ser considerados como indício radiológico de impressão basilar. 2 Foi observada correlação entre os valores dessa distância e os da existente entre o ápice da odontóide e a linha basal de McGregor, em 120 casos normais, com mais de 10 anos de idade. 3 Não foi encontrada diferença entre as médias da distância entre extremidade do dente axóideo e a linha bimastóidea nos sexos masculino e feminino. 4 Pelo menos até 20 anos de idade, há correlação entre os valores desta distância e a idade. Logo, até essa idade, o diagnóstico de impressão basilar deve ser feito perante menores valores dessa distância, sendo de aproximadamente +8 mm o limite superior da normalidade. 5 Nos casos de impressão basilar a média da distância entre ponta odontóidea e a linha de Fischgold-Metzger foi de +21,09 ± 10,03 mm, significantemente maior que a encontrada nos casos sem malformação occipitocervical. 6 Não houve correlação entre o grau de impressão basilar e a idade, ou entre as distâncias entre a extremidade axóidea e as linhas de Fischgold-Metzger e de McGregor nos casos dessa

  13. Plaques of Nonstenotic Basilar Arteries with Isolated Pontine Infarction on Three-dimensional High Isotropic Resolution Magnetic Resonance Imaging

    Institute of Scientific and Technical Information of China (English)

    Xian-Jin Zhu; Wei-Jian Jiang; Lei Liu; Li-Bin Hu; Wu Wang; Zun-Jing Liu

    2015-01-01

    Background:There are few studies for evaluating plaque characteristics of nonstenotic basilar arteries (BA).Our aim was to determine entire BA plaques with a three-dimensional volumetric isotropic turbo spin-echo acquisition (VISTA) and investigate the differences between the patients with and without isolated pontine infarction (IPI).Methods:Twenty-four consecutive symptomatic patients with nonstenotic BA on time of flight magnetic resonance angiography (TOF MRA) were enrolled from China-Japan Friendship Hospital between January 2014 and December 2014.BA was classified as "normal" or"irregular" based on TOF MRA,and "normal wall","slight wall-thickening",and "plaque" based on three-dimensional VISTA images.Outcomes from MRA and VISTA were compared.Patients were categorized as IPI and non-IPI groups based on the diffusion-weighted imaging.Clinical and plaque characteristics were compared between the two groups.Results:A total of 1024 image slices including 311 (30.37%) plaque slices,427 (41.70%) slight wall-thickening slices,and 286 (27.93%) normal wall slices for the entire BA from 23 patients were finally included for analysis.VISTA images detected plaques in all the 9 (100%) irregular MRA patients and 7 of 14 (50%) normal MRA patients.IPI was found in 1 1 (47.83%) patients.Compared to non-IPI group,the IPI group had a higher percentage of plaque slices (P =0.001) and lower percentage of normal wall slices (P =0.014) than non-IPI group.Conclusions:Three-dimensional VISTA images enable detection of BA plaques not visualized by MRA.BA plaques could be found in both the IPI and non-IPI group.However,IPI group showed plaques more extensively in BA than the non-IPI group.

  14. One-off surgery of posterior reduction and fixation for the treatment of basilar invagination with atlantoaxial dislocation

    Directory of Open Access Journals (Sweden)

    LIU Jia-gang

    2012-08-01

    Full Text Available Objective To investigate the surgical treatment and clinical results for the primary basilar invagination (BI with atlantoaxial dislocation (AAD. Methods A retrospective study was performed. The study included 89 patients who had primary BI and AAD were surgically treated in our hospital from January 2008 to December 2011. There were 28 males and 61 females, aged between 10 and 69 years (mean 45.42 years. All patients were treated by the same 3-step surgical method. The first step, reduction of the AAD was performed by homemade odontoid repositor intraoperatively through posterior approach; the second step, AO stainless steel plates were fixed between the occiput and C2, 3 lateral mass screws; and the third step, occipitocervical fusion were completed by autologous iliac crest graft. Operation effect was recorded during follow-up period. Results Follow-up period was 6 to 48 months. Clinical symptoms were improved in 82.93% patients after the surgery. Japanse Orthopaedic Association (JOA score increased from preoperative (8.80 ± 1.36 points to postoperative (15.35 ± 1.47 points (t = 17.225, P = 0.001. In general, satisfactory decompression and bony fusion were shown on postoperative radiological examinations for all patients. Compared with pretreatment data, the postoperative imaging measurement showed that the mean data of atlanto-dental interval (ADI, 9.22 mm vs 3.72 mm and vertical dimension from the top of odontoid process to Chamberlain line (10.41 mm vs 3.23 mm were all reduced, and the cervicomedullary angle (130° vs 150° and space available of spinal cord (SAC, 11.13 mm vs 15.54 mm were all improved. Conclusion The one-off surgery of posterior reduction technique and fixing between occiput and C2, 3 lateral mass screws is a safe, easy, and effective treatment for patients with p

  15. EFFECTS OF RESTRICTED BASILAR PAPILLAR LESIONS AND HAIR CELL REGENERATION ON AUDITORY FOREBRAIN FREQUENCY ORGANIZATION IN ADULT EUROPEAN STARLINGS

    Science.gov (United States)

    Irvine, Dexter R. F.; Brown, Mel; Kamke, Marc R.; Rubel, Edwin W

    2009-01-01

    The frequency organization of neurons in the forebrain Field L complex (FLC) of adult starlings was investigated to determine the effects of hair cell (HC) destruction in the basal portion of the basilar papilla (BP) and of subsequent HC regeneration. Conventional microelectrode mapping techniques were used in normal starlings and in lesioned starlings either 2 days or 6–10 weeks after aminoglycoside treatment. Histological examination of the BP and recordings of auditory brainstem evoked responses confirmed massive loss of HCs in the basal portion of the BP and hearing losses at frequencies above 2 kHz in starlings tested 2 days after aminoglycoside treatment. In these birds, all neurons in the region of the FLC in which CFs normally increase from 2 to 6 kHz had characteristic frequency (CF) in the range 2–4 kHz. The significantly elevated thresholds of responses in this region of altered tonotopic organization indicated that they were the residue of pre-lesion responses and did not reflect central nervous system plasticity. In the long-term recovery birds, there was histological evidence of substantial HC regeneration. The tonotopic organization of the high frequency region of the FLC did not differ from that in normal starlings, but the mean threshold at CF in this frequency range was intermediate between the values in the normal and lesioned short-recovery groups. The recovery of normal tonotopicity indicates considerable stability of the topography of neuronal connections in the avian auditory system, but the residual loss of sensitivity suggests deficiencies in high-frequency HC function. PMID:19474314

  16. Effects of restricted basilar papillar lesions and hair cell regeneration on auditory forebrain frequency organization in adult European starlings.

    Science.gov (United States)

    Irvine, Dexter R F; Brown, Mel; Kamke, Marc R; Rubel, Edwin W

    2009-05-27

    The frequency organization of neurons in the forebrain Field L complex (FLC) of adult starlings was investigated to determine the effects of hair cell (HC) destruction in the basal portion of the basilar papilla (BP) and of subsequent HC regeneration. Conventional microelectrode mapping techniques were used in normal starlings and in lesioned starlings either 2 d or 6-10 weeks after aminoglycoside treatment. Histological examination of the BP and recordings of auditory brainstem evoked responses confirmed massive loss of HCs in the basal portion of the BP and hearing losses at frequencies >2 kHz in starlings tested 2 d after aminoglycoside treatment. In these birds, all neurons in the region of the FLC in which characteristic frequencies (CFs) normally increase from 2 to 6 kHz had CF in the range of 2-4 kHz. The significantly elevated thresholds of responses in this region of altered tonotopic organization indicated that they were the residue of prelesion responses and did not reflect CNS plasticity. In the long-term recovery birds, there was histological evidence of substantial HC regeneration. The tonotopic organization of the high-frequency region of the FLC did not differ from that in normal starlings, but the mean threshold at CF in this frequency range was intermediate between the values in the normal and lesioned short-recovery groups. The recovery of normal tonotopicity indicates considerable stability of the topography of neuronal connections in the avian auditory system, but the residual loss of sensitivity suggests deficiencies in high-frequency HC function.

  17. Thrombolysis of the basilar artery: 5-year results from the Saarland stroke registry; Thrombolyse der A. basilaris: Ergebnisse im Saarland ueber einen Zeitraum von 5 Jahren

    Energy Technology Data Exchange (ETDEWEB)

    Grunwald, I.Q.; Struffert, T.; Roth, C.; Papanagiotou, P.; Scheuermann, J.; Voges, M.; Reith, W. [Universitaetsklinikum des Saarlandes Homburg (Germany). Klinik fuer Diagnostische und Interventionelle Neuroradiologie

    2005-05-01

    Acute thrombosis of the basilar artery has a fatal outcome if left untreated. The relatively good prognosis with intra-arterial thrombolysis makes it the therapy of choice for acute basilar thrombosis. In the Saarland stroke registry, we analyzed 47 patients with angiographically proven basilar artery thrombosis within the last 5 years. We observed a better outcome in patients with good income, with recanalization, and a short time between onset of symptoms and start of thrombolysis. The complications, such as intracerebral bleedings, occurred only in the group treated with rt-PA. Intra-arterial thrombolysis with urokinase or rt-PA is a relatively safe therapy, but should be performed in neuroradiological centers. With progressing symptoms the therapeutic window can be stretched up to 12 h, but coma lasting for more than 4 h is related to a bad outcome. (orig.) [German] Der akute Verschluss der A. basilaris fuehrt unbehandelt in der Regel rasch zum Tod. Aufgrund des zumeist fatalen Ausgangs unbehandelter Basilaristhrombosen und der relativ guten Prognose bei Behandlung mit lokaler intraarterieller Thrombolyse wird diese Therapie als das Mittel der Wahl bei akuter Basilaristhrombose angesehen. Anhand des Saarlaendischen Schlaganfallregisters wurden 47 Patienten mit einer nachgewiesenen Basilaristhrombose ueber einen Zeitraum von 5 Jahren in diese Studie eingeschlossen. Es konnte nachgewiesen werden, dass eine kurze Zeit bis zum Therapiebeginn, ein gutes Income sowie eine erfolgreiche Rekanalisation mit einem guten klinischen Outcome korreliert waren. Komplikationen traten ausnahmslos bei einer Lysetherapie mit rt-PA auf. Die intraarterielle Behandlung von Basilarisverschluessen mit Urokinase oder rt-PA sollte an spezialisierten, interventionellangiographisch taetigen Zentren vorgenommen werden. Bei fluktuierendem Beginn kann das Zeitfenster bis zu 12 h betragen, nach einer Komadauer von mehr als 4 h ist in der Regel kein guenstiges Outcome zu erwarten. (orig.)

  18. The mechanism of the NH4 ion oscillatory transport across the excitable cell membrane

    Directory of Open Access Journals (Sweden)

    Radenović Čedomir N.

    2005-01-01

    Full Text Available This paper presents results on typical oscillations of the membrane potential induced by the excitation of the cell membrane by different concentrations of the NH4Cl solution. The existence of four classes of oscillations of the membrane potential and several different single and local impulses rhythmically occurring were determined. It is known that the oscillatory processes of the membrane potential are in direct dependence on oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane. A hypothesis on a possible mechanism of oscillatory transport processes of NH4 and Cl ions across the excitable cell membrane is also presented.

  19. From excitability to oscillations

    DEFF Research Database (Denmark)

    Postnov, D. E.; Neganova, A. Y.; Jacobsen, J. C. B.;

    2013-01-01

    One consequence of cell-to-cell communication is the appearance of synchronized behavior, where many cells cooperate to generate new dynamical patterns. We present a simple functional model of vasomotion based on the concept of a two-mode oscillator with dual interactions: via relatively slow...

  20. Neutrino oscillation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Camilleri, L. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-11-01

    Neutrino oscillation experiments ({nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub {tau}}) currently being performed at accelerators are reviewed. Future plans for short and long base-line experiments are summarized. (author) 10 figs., 2 tabs., 29 refs.

  1. Multiphoton coherent population oscillation

    CERN Document Server

    Sharypov, A V

    2014-01-01

    We study the bichromatic driving of a two-level system which displays long-lived coherent population oscillations (CPO). We show that under certain conditions, multiphoton parametric interaction leads to the appearance of CPO resonances at the subharmonic frequencies. In addition, in the region of the CPO resonances, there is strong parametric interaction between the weak sideband components of the electromagnetic field.

  2. A simple violin oscillator

    Science.gov (United States)

    Jones, R. T.

    1976-01-01

    For acoustic tests the violin is driven laterally at the bridge by a small speaker of the type commonly found in pocket transistor radios. An audio oscillator excites the tone which is picked up by a sound level meter. Gross patterns of vibration modes are obtained by the Chladni method.

  3. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef;

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...

  4. [Oscillating physiotherapy for secretolysis].

    Science.gov (United States)

    Brückner, U

    2008-03-01

    Assisted coughing and mechanical cough aids compensate for the weak cough flow in patients with neuromuscular diseases (NMD). In cases with preserved respiratory muscles also breathing techniques and special devices, e. g., flutter or acapella can be used for secretion mobilisation during infections of the airways. These means are summarised as oscillating physiotherapy. Their mechanisms are believed to depend on separation of the mucus from the bronchial wall by vibration, thus facilitating mucus transport from the peripheral to the central airways. In mucoviscidosis and chronic obstructive pulmonary disease their application is established, but there is a paucity of data regarding the commitment in patients with neuromuscular diseases. The effective adoption of simple oscillation physiotherapeutic interventions demands usually a sufficient force of the respiratory muscles--exceptions are the application of the percussionaire (intrapulmonary percussive ventilator, IPV) or high frequency chest wall oscillation (HFCWO). In daily practice there is evidence that patients with weak respiratory muscles are overstrained with the use of these physiotherapeutic means, or get exhausted. A general recommendation for the adoption of simple oscillating physiotherapeutic interventions cannot be made in patients with NMDs. Perhaps in the future devices such as IPV or HFCWO will prove to be more effective in NMD patients.

  5. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.;

    2007-01-01

    to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure...

  6. A case of transient hypothermia after trans-lamina terminalis and third ventricle clipping of an extremely high-position basilar tip aneurysm

    Directory of Open Access Journals (Sweden)

    Toshikazu Hidaka

    2015-03-01

    Full Text Available Reports on the trans-lamina terminalis and trans-third ventricular approach are rare. The risk associated with this approach is unknown. After an unsuccessful endovascular surgery, we performed direct surgical clipping via the third ventricle on a 78-year-old woman presenting with an extremely high-positioned, ruptured basilar tip aneurysm. She experienced transient hypothermia for 5 days, and it was considered that this was due to hypothalamic dysfunction. It is necessary to recognize that there is the potential for hypothermia after surgery via the lamina terminalis and third ventricle, even though the mechanisms of hypothalamic thermoregulation are still unclear.

  7. Congenital absence of the internal carotid artery and the basilar artery with persistent trigeminal artery associated with coarctation of the aorta

    Energy Technology Data Exchange (ETDEWEB)

    Jaeger, H.J.; Mehring, U.M.; Gissler, H.M.; Mathias, K.D. [Dept. of Diagnostic Radiology, Staedtische Kliniken Dortmund (Germany); Dept. of Radiology and MicroTherapy, Univ. of Witten/Herdecke (Germany)

    2000-11-01

    We report a case of congenital absence of the cervical and petrous part of the left internal carotid artery, the middle and proximal part of the basilar artery, and the V4 segment of the left vertebral artery associated with a left persistent trigeminal artery and a coarctation of the aorta. The left cerebral vessels are supplied via the anterior communicating artery and the left persistent trigeminal artery. The coexisting coarctation of the aorta led to a subclavian steal phenomenon. The alteration of the cerebral hemodynamics has to be taken in consideration when performing cerebral angiography and surgical correction in such a case. (orig.)

  8. Outward potassium current oscillations in macrophage polykaryons: extracellular calcium entry and calcium-induced calcium release

    Directory of Open Access Journals (Sweden)

    Saraiva R.M.

    1997-01-01

    Full Text Available Outward current oscillations associated with transient membrane hyperpolarizations were induced in murine macrophage polykaryons by membrane depolarization in the absence of external Na+. Oscillations corresponded to a cyclic activation of Ca2+-dependent K+ currents (IKCa probably correlated with variations in intracellular Ca2+ concentration. Addition of external Na+ (8 mM immediately abolished the outward current oscillations, suggesting that the absence of the cation is necessary not only for their induction but also for their maintenance. Oscillations were completely blocked by nisoldipine. Ruthenium red and ryanodine reduced the number of outward current cycles in each episode, whereas quercetin prolonged the hyperpolarization 2- to 15-fold. Neither low molecular weight heparin nor the absence of a Na+ gradient across the membrane had any influence on oscillations. The evidence suggests that Ca2+ entry through a pathway sensitive to Ca2+ channel blockers is elicited by membrane depolarization in Na+-free medium and is essential to initiate oscillations, which are also dependent on the cyclic release of Ca2+ from intracellular Ca2+-sensitive stores; Ca2+ ATPase acts by reducing intracellular Ca2+, thus allowing slow deactivation of IKCa. Evidence is presented that neither a Na+/Ca2+ antiporter nor Ca2+ release from IP3-sensitive Ca2+ stores participate directly in the mechanism of oscillation

  9. Microwave transistor oscillator frequency tripling

    OpenAIRE

    B. A. Kotserzhynskyi

    2010-01-01

    The frequency tripler state of the art is consided. The oscillator-frequency tripler design is now at the state of scientific research. Microwave companies release the devices of the such structure: oscillator, buffer, amplifier-tripler.

  10. Microwave transistor oscillator frequency tripling

    Directory of Open Access Journals (Sweden)

    B. A. Kotserzhynskyi

    2010-01-01

    Full Text Available The frequency tripler state of the art is consided. The oscillator-frequency tripler design is now at the state of scientific research. Microwave companies release the devices of the such structure: oscillator, buffer, amplifier-tripler.

  11. Neutrino Velocity and Neutrino Oscillations

    CERN Document Server

    Minakata, H

    2012-01-01

    We study distances of propagation and the group velocities of the muon neutrinos in the presence of mixing and oscillations assuming that Lorentz invariance holds. Oscillations lead to distortion of the $\

  12. Neutrino Oscillations with Nil Mass

    Science.gov (United States)

    Floyd, Edward R.

    2016-09-01

    An alternative neutrino oscillation process is presented as a counterexample for which the neutrino may have nil mass consistent with the standard model. The process is developed in a quantum trajectories representation of quantum mechanics, which has a Hamilton-Jacobi foundation. This process has no need for mass differences between mass eigenstates. Flavor oscillations and ν ,bar{ν } oscillations are examined.

  13. Multicomponent membranes

    Science.gov (United States)

    Kulprathipanja, Santi; Kulkarni, Sudhir S.; Funk, Edward W.

    1988-01-01

    A multicomponent membrane which may be used for separating various components which are present in a fluid feed mixture comprises a mixture of a plasticizer such as a glycol and an organic polymer cast upon a porous organic polymer support. The membrane may be prepared by casting an emulsion or a solution of the plasticizer and polymer on the porous support, evaporating the solvent and recovering the membrane after curing.

  14. Ouabain, a steroid hormone that signals with slow calcium oscillations.

    Science.gov (United States)

    Aizman, O; Uhlén, P; Lal, M; Brismar, H; Aperia, A

    2001-11-06

    The plant-derived steroid, digoxin, a specific inhibitor of Na,K-ATPase, has been used for centuries in the treatment of heart disease. Recent studies demonstrate the presence of a digoxin analog, ouabain, in mammalian tissue, but its biological role has not been elucidated. Here, we show in renal epithelial cells that ouabain, in doses causing only partial Na,K-ATPase inhibition, acts as a biological inducer of regular, low-frequency intracellular calcium ([Ca(2+)](i)) oscillations that elicit activation of the transcription factor, NF-kappa B. Partial inhibition of Na,K-ATPase using low extracellular K(+) and depolarization of cells did not have these effects. Incubation of cells in Ca(2+)-free media, inhibition of voltage-gated calcium channels, inositol triphosphate receptor antagonism, and redistribution of actin to a thick layer adjacent to the plasma membrane abolished [Ca(2+)](i) oscillations, indicating that they were caused by a concerted action of inositol triphosphate receptors and capacitative calcium entry via plasma membrane channels. Blockade of ouabain-induced [Ca(2+)](i) oscillations prevented activation of NF-kappa B. The results demonstrate a new mechanism for steroid signaling via plasma membrane receptors and underline a novel role for the steroid hormone, ouabain, as a physiological inducer of [Ca(2+)](i) oscillations involved in transcriptional regulation in mammalian cells.

  15. Recording Gamma Band Oscillations in Pedunculopontine Nucleus Neurons.

    Science.gov (United States)

    Urbano, Francisco J; Luster, Brennon R; D'Onofrio, Stasia; Mahaffey, Susan; Garcia-Rill, Edgar

    2016-09-14

    Synaptic efferents from the PPN are known to modulate the neuronal activity of several intralaminar thalamic regions (e.g., the centrolateral/parafascicular; Cl/Pf nucleus). The activation of either the PPN or Cl/Pf nuclei in vivo has been described to induce the arousal of the animal and an increment in gamma band activity in the cortical electroencephalogram (EEG). The cellular mechanisms for the generation of gamma band oscillations in Reticular Activating System (RAS) neurons are the same as those found to generate gamma band oscillations in other brains nuclei. During current-clamp recordings of PPN neurons (from parasagittal slices from 9 - 25 day-old rats), the use of depolarizing square steps rapidly activated voltage-dependent potassium channels that prevented PPN neurons from being depolarized beyond -25 mV. Injecting 1 - 2 sec long depolarizing current ramps gradually depolarized PPN membrane potential resting values towards 0 mV. However, injecting depolarizing square pulses generated gamma-band oscillations of membrane potential that showed to be smaller in amplitude compared to the oscillations generated by ramps. All experiments were performed in the presence of voltage-gated sodium channels and fast synaptic receptors blockers. It has been shown that the activation of high-threshold voltage-dependent calcium channels underlie gamma-band oscillatory activity in PPN neurons. Specific methodological and pharmacological interventions are described here, providing the necessary tools to induce and sustain PPN subthreshold gamma band oscillation in vitro.

  16. Voltage-controlled photonic oscillator.

    Science.gov (United States)

    Savchenkov, A A; Ilchenko, V S; Liang, W; Eliyahu, D; Matsko, A B; Seidel, D; Maleki, L

    2010-05-15

    We report the development and demonstration of an X-band voltage-controlled photonic oscillator based on a whispering gallery mode resonator made of an electro-optic crystalline material. The oscillator has good spectral purity and wide, agile, linear tunability. We have modified the existing theoretical model of the opto-electronic oscillator to describe the performance of our tunable oscillator and have found a good agreement between the theoretical predictions and the measurement results. We show that the device is promising for higher-frequency applications where high-performance tunable oscillators with wide tunability do not exist.

  17. Study on the travelling and anatomical variations of basilar artery via VCTDSA%基底动脉走行和变异的容积CT数字减影血管成像研究

    Institute of Scientific and Technical Information of China (English)

    唐贵超; 陈莉; 吕发金

    2013-01-01

    Objective To investigate the anatomical variations and travelling of basilar artery via volume computed tomography digital subtraction angiography (VCTDSA) and to investigate the relationship between the basilar artery bending and the development of intracranial segment of vertebral artery.Methods A total of 110 normal subjects underwent cerebral and cervical vessel VCTDSA were involved in the present study,and the images of basilar arteries were reconstructed by VR images.The development of vertebral artery,window variation and tortuosity of basilar artery,as well as the diameter and length of basilar artery were measured.The correlation between development of vertebral artery and tortuosity of basilar artery were analyzed.Results (1)In the 110cases,the rate of hypoplastic vertebral artery,tortuosity and window variation of basilar artery were 17.27% (19/110),22.73%(25/110) and 2.73%(3/110),respectively.(2)The average length and diameter of basilar artery were(28.25±3.88)mm and (3.86±0.54)mm,respectively.(3)The tortuosity and window variation of basilar artery showed positive correlation with the development of intracranial segment of vertebral artery(P<0.01,r=0.52).Conclusion VCTDSA could clearly show the anatomy and variability of basilar artery,and its anatomic valuable could act as the reference for the diagnosis of cerebral diseases in clinic.The hypoplasia of intracranial segment of vertebral artery could be correlate with tortuosity of basilar artery.%目的 运用容积CT数字减影血管成像(VCTDSA)研究基底动脉走行和变异,探讨基底动脉迂曲与椎动脉颅内段发育不良之间的关系.方法 观测2010年1月至2011年12月在重庆医科大学附属第一医院行VCTDSA检查、非脑卒中患者且头部或头颈VCTDSA检查未见病变者110例,在容积再现(VR)图像上观察双侧椎动脉颅内段发育情况、基底动脉有无迂曲、是否存在窗型变异,并分别测量基底动脉的长度与管径,同时

  18. Physics of Neutrino Oscillation

    CERN Document Server

    Mondal, Spandan

    2015-01-01

    The Standard Model of particle physics describes neutrinos as massless, chargeless elementary particles that come in three different flavours. However, recent experiments indicate that neutrinos not only have mass, but also have multiple mass eigenstates that are not identical to the flavour states, thereby indicating mixing. As an evidence of mixing, neutrinos have been observed to change from one flavour to another during their propagation, a phenomenon called neutrino oscillation. We have studied the reasons and derived the probabilities of neutrino flavour change, both in vacuum and in matter. We have also studied the parameters affecting this probability. We have discussed the special case of two-neutrino oscillations. Lastly, we have discussed some basic properties of neutrinos that are reflected in the previous derivations and highlighted a few relevant open problems. To begin with, we have also studied the relevant topics in introductory High Energy Physics and Quantum Mechanics to familiarize with th...

  19. Stable local oscillator module.

    Energy Technology Data Exchange (ETDEWEB)

    Brocato, Robert Wesley

    2007-11-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.

  20. Entanglement in neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Blasone, M.; Dell' Anno, F.; De Siena, S.; Illuminati, F. [Universita degli Studi di Salerno Via Ponte don Melillon, Dipt. di Matematica e Informatica, Fisciano SA (Italy); INFN Sezione di Napoli, Gruppo collegato di Salerno - Baronissi SA (Italy); Dell' Anno, F.; De Siena, S.; Illuminati, F. [CNR-INFM Coherentia - Napoli (Italy); Blasone, M. [ISI Foundation for Scientific Interchange, Torino (Italy)

    2009-03-15

    Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)

  1. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

    Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...

  2. Neutrino Masses and Oscillations

    CERN Document Server

    CERN. Geneva. Audiovisual Unit; Treille, Daniel

    2002-01-01

    This course will not cover its subject in the customary way. The emphasis will be on the simple theoretical concepts (helicity, handedness, chirality, Majorana masses) which are obscure in most of the literature, and on the quantum mechanics of oscillations, that ALL books get wrong. Which, hopefully, will not deter me from discussing some of the most interesting results from the labs and from the cosmos.

  3. Oscillations in the bispectrum

    CERN Document Server

    Meerburg, P Daniel

    2010-01-01

    There exist several models of inflation that produce primordial bispectra that contain a large number of oscillations. In this paper we discuss these models, and aim at finding a method of detecting such bispectra in the data. We explain how the recently proposed method of mode expansion of bispectra might be able to reconstruct these spectra from separable basis functions. Extracting these basis functions from the data might then lead to observational constraints on these models.

  4. Polychromatic optical Bloch oscillations.

    Science.gov (United States)

    Longhi, Stefano

    2009-07-15

    Bloch oscillations (BOs) of polychromatic beams in circularly curved optical waveguide arrays are smeared out owing to the dependence of the BO spatial period on the wavelength. Here it is shown that restoring of the self-imaging property of the array and approximate BOs over relatively broad spectral ranges can be achieved by the insertion of suitable lumped phase slips uniformly applied across the array.

  5. Basilar artery hypoplasia and its clinical significance%基底动脉发育不全及其临床意义

    Institute of Scientific and Technical Information of China (English)

    张道培; 张淑玲; 许予明

    2015-01-01

    基底动脉发育不全(basilar artery hypoplasia,BAH)在过去较少受到关注,但检出率的提高使得BAH的临床意义逐渐被认识.BAH与血管危险因素相互作用,可能促发后循环缺血事件的发生,脑诱发电位可作为早期检测这一病理生理学事件的重要手段.深入研究BAH的病理意义,有助于加深对后循环缺血事件发病机制的认识.%Basilar artery hypoplasia (BAH) has been paid less attention to in the past.However,the increased detection rate makes the clinical significance of BAH to be gradually recognized.BAH have interaction with vascular risk factors,and this may promote the occurrence of ischemic events in posterior circulation.Brain evoked potential can be used as an important means for early detection of this pathophysiological events.The depth study of pathological significance of BAH helps to deepen the understanding of the mechanisms of posterior circulation ischemic events.

  6. Y stenting assisted coiling using a new low profile visible intraluminal support device for wide necked basilar tip aneurysms: a technical report.

    Science.gov (United States)

    Conrad, Marcelo D; Brasiliense, Leonardo B C; Richie, Alexa N; Hanel, Ricardo A

    2014-05-01

    Many endovascular techniques have been described in recent years for the management of wide necked aneurysms. The Y stent assisted technique has been generally used for coil embolization of wide necked bifurcation aneurysms. This technique was first described for the treatment of basilar tip aneurysms in combination with several different devices, demonstrating encouraging results. We report the results of the first two cases of wide necked basilar tip aneurysms treated with Y stent assisted coil embolization using a new low profile visible intraluminal stent (LVIS Jr; MicroVention, Tustin, California, USA) delivered through a 0.017 inch microcatheter. We also reviewed the literature comparing other endovascular techniques (coiling alone, stent assisted coiling, and Y stent assisted coiling) for wide necked aneurysms. The LVIS Jr device offers a new option for the treatment of these challenging lesions, with clear advantages over currently available intracranial stents. Larger series and long term results are needed to confirm the applicability and durability of this technique/technology.

  7. Effect of ST36 Acupuncture on Hyperventilation-Induced CO2 Reactivity of the Basilar and Middle Cerebral Arteries and Heart Rate Variability in Normal Subjects

    Directory of Open Access Journals (Sweden)

    Sang-Ho Hyun

    2014-01-01

    Full Text Available This study was conducted to verify the effect of acupuncture on cerebral haemodynamics to provide evidence for the use of acupuncture treatment as a complementary therapy for the high-risk stroke population. The effect of ST36 acupuncture treatment on the hyperventilation-induced CO2 reactivity of the basilar and middle cerebral arteries was studied in 10 healthy male volunteers (mean age, 25.2 ± 1.5 years using a transcranial Doppler sonography with an interval of 1 week between measurements, and a portable ECG monitoring system was used to obtain ECG data simultaneously. The CO2 reactivity of the basilar and middle cerebral arteries increased significantly after ST36 acupuncture treatment, whereas the mean arterial blood pressure and pulse rate did not change significantly. The high-frequency power significantly increased after ST36 acupuncture treatment, and the percentage increase of high-frequency power correlated significantly with the percentage increase in the CO2 reactivity of the contralateral middle cerebral artery. These data suggest that ST36 acupuncture treatment increases CO2 reactivity, indicating improvement of vasodilatory potential of the cerebral vasculature to compensate for fluctuations caused by changes in external conditions. The increase in parasympathetic tone by ST36 acupuncture treatment is responsible for this therapeutic effect.

  8. Temperature sensitive oscillator

    Science.gov (United States)

    Kleinberg, L. L. (Inventor)

    1986-01-01

    An oscillator circuit for sensing and indicating temperature by changing oscillator frequency with temperature comprises a programmable operational amplifier which is operated on the roll-off portion of its gain versus frequency curve and has its output directly connected to the inverting input to place the amplifier in a follower configuration. Its output is also connected to the non-inverting input by a capacitor with a crystal or other tuned circuit also being connected to the non-inverting input. A resistor is connected to the program input of the amplifier to produce a given set current at a given temperature, the set current varying with temperature. As the set current changes, the gain-bandwidth of the amplifier changes and, in turn, the reflected capacitance across the crystal changes, thereby providing the desired change in oscillator frequency by pulling the crystal. There is no requirement that a crystal employed with this circuit display either a linear frequency change with temperature or a substantial frequency change with temperature.

  9. Nonlinear Oscillators in Space Physics

    Science.gov (United States)

    Lester,Daniel; Thronson, Harley

    2011-01-01

    We discuss dynamical systems that produce an oscillation without an external time dependent source. Numerical results are presented for nonlinear oscillators in the Em1h's atmosphere, foremost the quasi-biennial oscillation (QBOl. These fluid dynamical oscillators, like the solar dynamo, have in common that one of the variables in a governing equation is strongly nonlinear and that the nonlinearity, to first order, has particular form. of 3rd or odd power. It is shown that this form of nonlinearity can produce the fundamental li'equency of the internal oscillation. which has a period that is favored by the dynamical condition of the fluid. The fundamental frequency maintains the oscillation, with no energy input to the system at that particular frequency. Nonlinearities of 2nd or even power could not maintain the oscillation.

  10. El cierre de la sincondrosis esfeno-basilar y su influencia en la morfología craneofacial

    Directory of Open Access Journals (Sweden)

    Sardi, Marina Laura

    2008-01-01

    Full Text Available El principal centro de crecimiento de la base craneana durante la ontogenia postnatal es la sincondrosis esfeno-basilar (SEB, que permite la elongación de la línea media en el piso craneano. Su actividad de crecimiento termina entre los 12 a 15 años y su cierre se produce luego de la pubertad. El objetivo de este estudio fue analizar el crecimiento craneofacial entre los 11 y 19 años de edad para determinar si el cierre de la SEB es un evento asociado a cambios en la morfología craneofacial. Se probaron las siguientes hipótesis: a los individuos con la SEB fusionada tienen tamaño significativamente mayor que aquellos que aún tienen la SEB abierta; b la diferenciación de tamaño entre individuos con SEB abierta y fusionada se asocia a cambios en las trayectorias de crecimiento. Se utilizaron 118 cráneos con edad de muerte entre 11 y 19 años. Cada individuo se clasificó según el estado de la SEB (ESEB en: SEBA, aquellos en los que la SEB no está completamente fusionada y SEBF, cuando la superficie exocraneal de la SEB se ha osificado. Se midieron la longitud, ancho y altura de los siguientes componentes craneanos: anteroneural, mesoneural, posteroneural, óptico, respiratorio, masticatorio y alveolar, así como la longitud neural total. Se realizaron análisis de Componentes Principales (ACP y de la Covarianza (ANCOVA, considerando como efectos en la variación al ESEB, la edad y su interacción (ESEB vs edad. Ambos análisis indicaron que hay cambios asociados a la edad. Según ANCOVA, la longitud del componente mesoneural fue la única variable en que hubo diferenciación significativa entre SEBA y SEBF, estando la edad controlada y también fue la única medida, en que la interacción con la edad fue significativa; sin embargo, la diferencia de tamaño es opuesta a lo esperado, mayor en SEBA. Por lo tanto, las hipótesis propuestas se rechazan. La variación se asoció a la edad, pero no a ESEB. Es posible que la actividad osteog

  11. Contribuição ao estudo das malformações occipito-cervical, particularmente da impressão basilar

    Directory of Open Access Journals (Sweden)

    Horacio M. Canelas

    1952-12-01

    Full Text Available The authors outline the development of the spine and skull, particularly of axis, atlas and occipital bone. As neuro-skeletal dysmorphisms, the occipito-cervical malformations belong to the neurodysplastic group. They are classified as skeletal anomalies, associated nervous malformations and meningeal reactions. Vertebralization of the occipital bone and occipitalization of atlas, subluxation of odontoid process, dysplasia of the occipital bone, dystrophia brevicollis and other anomalies are discussed. Special care is given to the study of basilar impression; its concept, history, incidence, clinical and neurological symptoms, radiological characterization (craniographic, perimyelographic and iodoventriculographic aspects and surgical treatment are reviewed. The authors report five cases of occipito-cervical malformations, which are the first references in Brazilian literature. In case 1 the anomalies (manifestation of occipital vertebra and Arnold-Chiari deformity were disclosed at an operation for cisticercosis of the posterior fossa. In the following four cases invagination of the basilar portion of the occipital bone (basilar impression could be radiologically demonstrated; in case 2 a suboccipital craniectomy and a laminectomy of atlas and axis were performed but the patient died a week later and the necroscopic examination confirmed the neuro-skeletal anomalies. In all cases there were several associated malformations. In case 2 there were occipitalization of the atlas, fusion of the first and second cervical vertebrae, supernumerary rib of the seventh cervical vertebra, supernumerary lumbar vertebra, and Arnold-Chiari deformity; at necropsy it was found a syringomyelic cyst on the cervical cord and a fibrous dural ring over the foramen magnum. Case 3 showed the syndrome of Klippel-Feil, besides supernumerary ribs of the seventh cervical and first dorsal vertebrae, Arnold-Chiari malfotmation and probable aplasia of cell groups in the

  12. Multilayered Magnetic Gelatin Membrane Scaffolds

    Science.gov (United States)

    Samal, Sangram K.; Goranov, Vitaly; Dash, Mamoni; Russo, Alessandro; Shelyakova, Tatiana; Graziosi, Patrizio; Lungaro, Lisa; Riminucci, Alberto; Uhlarz, Marc; Bañobre-López, Manuel; Rivas, Jose; Herrmannsdörfer, Thomas; Rajadas, Jayakumar; De Smedt, Stefaan; Braeckmans, Kevin; Kaplan, David L.; Dediu, V. Alek

    2016-01-01

    A versatile approach for the design and fabrication of multilayer magnetic scaffolds with tunable magnetic gradients is described. Multilayer magnetic gelatin membrane scaffolds with intrinsic magnetic gradients were designed to encapsulate magnetized bioagents under an externally applied magnetic field for use in magnetic-field-assisted tissue engineering. The temperature of the individual membranes increased up to 43.7 °C under an applied oscillating magnetic field for 70 s by magnetic hyperthermia, enabling the possibility of inducing a thermal gradient inside the final 3D multilayer magnetic scaffolds. On the basis of finite element method simulations, magnetic gelatin membranes with different concentrations of magnetic nanoparticles were assembled into 3D multilayered scaffolds. A magnetic-gradient-controlled distribution of magnetically labeled stem cells was demonstrated in vitro. This magnetic biomaterial–magnetic cell strategy can be expanded to a number of different magnetic biomaterials for various tissue engineering applications. PMID:26451743

  13. Acquisition of a Nd-Yag Pumped MOPO (Master Oscillator/Power Oscillator) Optical Parametric Oscillator

    Science.gov (United States)

    1997-09-30

    SEP 1997 2. REPORT TYPE 3. DATES COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Acquisition of a Nd-Yag Pumped MOPO (Master Oscillator...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 ACQUISITION OF A ND-YAG PUMPED MOPO (MASTER OSCILLATOR / POWER OSCILLATOR) OPTICAL...instrument is configured in a master oscillator/power oscillator configuration, hence the designation MOPO . The MOPO will be used in conjunction

  14. Theory on Plasmon Modes of the Cell Membranes

    CERN Document Server

    Nhan, T T; Ngo, V Thanh; Viet, N A

    2007-01-01

    Considering the plasmon oscillation of each layer of the cell membranes as a quasi-particle, we introduce a simple model for the membrane collective charge excitations, take into account the surface effective potential of the plasmon-plasmon interaction between two layers. By using the useful Bogoliubov transformation method, we easily obtained the expressions of the frequencies of plasmon oscillations as a function of wave-number $k$ and membrane thickness $d$, magnitude of these frequencies is in the order of $\\sqrt{kd}$. Our results are in good agreement with ones obtained by E. Manousakis.

  15. Wiener kernels of chinchilla auditory-nerve fibers : Verification using responses to tones, clicks, and noise and comparison with basilar-membrane vibrations

    NARCIS (Netherlands)

    Temchin, AN; Recio-Spinoso, A; van Dijk, P; Ruggero, MA

    2005-01-01

    Responses to tones, clicks, and noise were recorded from chinchilla auditory-nerve fibers (ANFs). The responses to noise were analyzed by computing the zeroth-, first-, and second-order Wiener kernels (h(0), h(1), and h(2)). The h(1) s correctly predicted the frequency tuning and phases of responses

  16. The ELANA technique : Constructing a high flow bypass using a non-occlusive anastomosis on the ICA and a conventional anastomosis on the SCA in the treatment of a fusiform giant basilar trunk aneurysm

    NARCIS (Netherlands)

    Streefkerk, HJN; Wolfs, JFC; Sorteberg, W; Sorteberg, AG; Tulleken, CAF

    2004-01-01

    A patient with a partially thrombosed fusiform giant basilar trunk aneurysm presented with devastating headache and symptoms of progressive brain stem compression. Having an aneurysm inaccessible for endovascular treatment, and after failing a vertebral artery balloon occlusion test, he was offered

  17. Modeling microtubule oscillations

    DEFF Research Database (Denmark)

    Jobs, E.; Wolf, D.E.; Flyvbjerg, H.

    1997-01-01

    Synchronization of molecular reactions in a macroscopic volume may cause the volume's physical properties to change dynamically and thus reveal much about the reactions. As an example, experimental time series for so-called microtubule oscillations are analyzed in terms of a minimal model...... for this complex polymerization-depolymerization cycle. The model reproduces well the qualitatively different time series that result from different experimental conditions, and illuminates the role and importance of individual processes in the cycle. Simple experiments are suggested that can further test...... and define the model and the polymer's reaction cycle....

  18. On particle oscillations

    CERN Document Server

    Góźdź, Marek

    2013-01-01

    It has been firmly established, that neutrinos change their flavour during propagation. This feature is attributed to the fact, that each flavour eigenstate is a superposition of three mass eigenstates, which propagate with different frequencies. This picture, although widely accepted, is wrong in the simplest approach and requires quite sophisticated treatment based on the wave-packet description within quantum field theory. In this communication we present a novel, much simpler explanation and show, that oscillations among massive particles can be obtained in a natural way. We use the framework of quantum mechanics with time being a physical observable, not just a parameter.

  19. Kravchuk oscillator revisited

    Science.gov (United States)

    Atakishiyeva, Mesuma K.; Atakishiyev, Natig M.; Wolf, Kurt Bernardo

    2014-05-01

    The study of irreducible representations of Lie algebras and groups has traditionally considered their action on functions of a continuous manifold (e.g. the 'rotation' Lie algebra so(3) on functions on the sphere). Here we argue that functions of a discrete variable -Kravchuk functions- are on equal footing for that study in the case of so(3). They lead to a discrete quantum model of the harmonic oscillator, and offer a corresponding set of special function relations. The technique is applicable to other special function families of a discrete variable, which stem from low-dimensional Lie algebras and are stationary solutions for the corresponding discrete quantum models.

  20. On Oscillating Dark Energy

    CERN Document Server

    Linder, E V

    2006-01-01

    Distance-redshift data can impose strong constraints on dark energy models even when the equation of state is oscillatory. Despite the double integral dependence of the distance on the equation of state, precision measurement of the distance-redshift relation for z=0-2 is more incisive than the linear growth factor, CMB last scattering surface distance, and the age of the universe in distinguishing oscillatory behavior from an average behavior. While oscillating models might help solve the coincidence problem (since acceleration occurs periodically), next generation observations will strongly constrain such possibilities.

  1. 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.

  2. Olfactory system oscillations across phyla.

    Science.gov (United States)

    Kay, Leslie M

    2015-04-01

    Neural oscillations are ubiquitous in olfactory systems of mammals, insects and molluscs. Neurophysiological and computational investigations point to common mechanisms for gamma or odor associated oscillations across phyla (40-100Hz in mammals, 20-30Hz in insects, 0.5-1.5Hz in molluscs), engaging the reciprocal dendrodendritic synapse between excitatory principle neurons and inhibitory interneurons in the olfactory bulb (OB), antennal lobe (AL), or procerebrum (PrC). Recent studies suggest important mechanisms that may modulate gamma oscillations, including neuromodulators and centrifugal input to the OB and AL. Beta (20Hz) and theta (2-12Hz) oscillations coordinate activity within and across brain regions. Olfactory beta oscillations are associated with odor learning and depend on centrifugal OB input, while theta oscillations are strongly associated with respiration.

  3. Intrinsic oscillations of neocortex generated by layer 5 pyramidal neurons.

    Science.gov (United States)

    Silva, L R; Amitai, Y; Connors, B W

    1991-01-25

    Rhythmic activity in the neocortex varies with different behavioral and pathological states and in some cases may encode sensory information. However, the neural mechanisms of these oscillations are largely unknown. Many pyramidal neurons in layer 5 of the neocortex showed prolonged, 5- to 12-hertz rhythmic firing patterns at threshold. Rhythmic firing was due to intrinsic membrane properties, sodium conductances were essential for rhythmicity, and calcium-dependent conductances strongly modified rhythmicity. Isolated slices of neocortex generated epochs of 4- to 10-hertz synchronized activity when N-methyl-D-aspartate receptor-mediated channels were facilitated. Layer 5 was both necessary and sufficient to produce these synchronized oscillations. Thus, synaptic networks of intrinsically rhythmic neurons in layer 5 may generate or promote certain synchronized oscillations of the neocortex.

  4. Intrinsic Oscillations of Neocortex Generated by Layer 5 Pyramidal Neurons

    Science.gov (United States)

    Silva, Laurie R.; Amitai, Yael; Connors, Barry W.

    1991-01-01

    Rhythmic activity in the neocortex varies with different behavioral and pathological states and in some cases may encode sensory information. However, the neural mechanisms of these oscillations are largely unknown. Many pyramidal neurons in layer 5 of the neocortex showed prolonged, 5- to 12-hertz rhythmic firing patterns at threshold. Rhythmic firing was due to intrinsic membrane properties, sodium conductances were essential for rhythmicity, and calcium-dependent conductances strongly modified rhythmicity. Isolated slices of neocortex generated epochs of 4- to 10-hertz synchronized activity when N-methyl-D-aspartate receptor-mediated channels were facilitated. Layer 5 was both necessary and sufficient to produce these synchronized oscillations. Thus, synaptic networks of intrinsically rhythmic neurons in layer 5 may generate or promote certain synchronized oscillations of the neocortex.

  5. C P -violating baryon oscillations

    Science.gov (United States)

    McKeen, David; Nelson, Ann E.

    2016-10-01

    We enumerate the conditions necessary for C P violation to be manifest in n -n ¯ oscillations and build a simple model that can give rise to such effects. We discuss a possible connection between neutron oscillations and dark matter, provided the mass of the latter lies between mp-me and mp+me. We apply our results to a possible baryogenesis scenario involving C P violation in the oscillations of the Ξ0.

  6. Linearization of conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belendez, A; Alvarez, M L [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E; Pascual, I [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es

    2009-03-11

    A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for the complete range of oscillation amplitudes. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of the technique.

  7. How pervasive are circadian oscillations?

    OpenAIRE

    2014-01-01

    Circadian oscillations play a critical role in coordinating the physiology, homeostasis, and behavior of biological systems. Once thought to only be controlled by a master clock, recent high-throughput experiments suggest many genes and metabolites in a cell are potentially capable of circadian oscillations. Each cell can reprogram itself and select a relatively small fraction of this broad repertoire for circadian oscillations, as a result of genetic, environmental, and even diet changes.

  8. 翼点入路手术治疗基底动脉顶端动脉瘤%Surgical treatment for basilar artery apex aneurysm via pterional approach

    Institute of Scientific and Technical Information of China (English)

    高成; 刘相轸; 陈会荣; 林成海; 李敬文; 赵振环

    2008-01-01

    目的 回顾分析基底动脉顶端动脉瘤的手术方法和疗效.方法 2002年1月至2006年1月手术治疗基底动脉顶端动脉瘤9例,其中男3例,女6例,年龄29~57岁(平均46.6±8.4岁).按照Hunt-Hess分级,Ⅰ级2例,Ⅱ级5例,Ⅲ级2例.全部患者采用翼点入路手术,术后复查脑血管造影,随访2个月-4年(平均19个月).结果 完全夹闭6例,不全夹闭1例,包裹2例.全部病人存活,按照GOS预后分级,Ⅴ级5例,Ⅳ级3例,Ⅲ级1例.结论 掌握手术技巧,熟悉脚间池的区域显微解剖,对具体病人进行个体化设计,是提高基底动脉顶端动脉瘤手术效果的关键.%Objective To review the method and outcome of surgical treatment for basilar artery apex aneurysms. Method Nine patients who suffered basilar artery apex aneurysms were operated from Jan. 2002 to Jan. 2006. Among these patients, 3 was man and 6 was women. The age is from 29 to 57 years and average is 46.6± 8.4. Two is grade Ⅰ, 5 is grade Ⅱ and 2 is grade Ⅲ according to the Hunt-Hess grading scale system. All patients were treated via pterional approach and post-operational DSA was done to evaluate the effect of operation. The period of follow-up was from 2 months to 4 years. Results None of the patients died of operation. Six aneurysms were clipped completely and 1 was clipped incompletely, and 2 was wrapping. According to the GOS scale, 5 patients were Ⅴ, 3 was Ⅳ and 1 was Ⅲ. Conclusions Surgical treatment is an important method for the therapy of the basilar artery apex aneurysms. Excellent surgical technique and familiarity with microanatomy of interpeduncular cistern is demanded for obtaining a good outcome.

  9. Experiments on Deflecting & Oscillating Waterjet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    A new type jet,the oscillating & deflecting jet ,is put forward and its oscillating and deflecting characteristics are investigated.The nozzle of the self-oscillating & deflecting water jet consists of an upstream nozzle,a downstream nozzle,an oscillating chamber and two switches,It is experimentally shown that the deflective angle may reach 9.53 degeree,the generated pressure fluctuation is very regular and the jet can efficiently increase the ability for bradking and cutting by eliminating the water cushion effect associated with a continuous jet.

  10. Oscillating nonlinear acoustic shock waves

    DEFF Research Database (Denmark)

    Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth

    2016-01-01

    We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show that at resona......We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...

  11. Unstable oscillators based hyperchaotic circuit

    DEFF Research Database (Denmark)

    Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.;

    1999-01-01

    A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...

  12. Hypothetical membrane mechanisms in essential tremor

    Directory of Open Access Journals (Sweden)

    Ramat Stefano

    2008-11-01

    Full Text Available Abstract Background Essential tremor (ET is the most common movement disorder and its pathophysiology is unknown. We hypothesize that increased membrane excitability in motor circuits has a key role in the pathogenesis of ET. Specifically, we propose that neural circuits controlling ballistic movements are inherently unstable due to their underlying reciprocal innervation. Such instability is enhanced by increased neural membrane excitability and the circuit begins to oscillate. These oscillations manifest as tremor. Methods Postural limb tremor was recorded in 22 ET patients and then the phenotype was simulated with a conductance-based neuromimetic model of ballistic movements. The model neuron was Hodgkin-Huxley type with added hyperpolarization activated cation current (Ih, low threshold calcium current (IT, and GABA and glycine mediated chloride currents. The neurons also featured the neurophysiological property of rebound excitation after release from sustained inhibition (post-inhibitory rebound. The model featured a reciprocally innervated circuit of neurons that project to agonist and antagonist muscle pairs. Results Neural excitability was modulated by changing Ih and/or IT. Increasing Ih and/or IT further depolarized the membrane and thus increased excitability. The characteristics of the tremor from all ET patients were simulated when Ih was increased to ~10× the range of physiological values. In contrast, increasing other membrane conductances, while keeping Ih at a physiological value, did not simulate the tremor. Increases in Ih and IT determined the frequency and amplitude of the simulated oscillations. Conclusion These simulations support the hypothesis that increased membrane excitability in potentially unstable, reciprocally innervated circuits can produce oscillations that resemble ET. Neural excitability could be increased in a number of ways. In this study membrane excitability was increased by up-regulating Ih and IT. This

  13. MULTIPLE OSCILLATION STABILIZING CONTROL.

    Energy Technology Data Exchange (ETDEWEB)

    YUE,M.; SCHLUETER,R.; AZARM,M.; BARI,R.

    2004-07-23

    This paper presents a strategy that may be used to guide stabilizing control design for multiple oscillations, which are difficult to control using conventional control design procedures. A multiple oscillation phenomena is observed in an example power system. A local bifurcation and an interarea bifurcation develop in an example power system due to multiple bifurcation parameter variations. The dynamic behaviors of the bifurcating system are complex due to the overlapping of the two different bifurcation subsystems and are shown to be difficult to control. The double bifurcations are studied in this paper and in order to stabilize them, three kind of {mu}-synthesis robust controls are designed, (a) {mu}-synthesis power system stabilizer (MPSS); (b) {mu}-synthesis SVC control (MSVC); and (c) a mixed MPSS/MSVC control. Based on the bifurcation subsystem analysis, the measurement signals and locations of the controls are selected. The control performances of three kind of controls are evaluated and compared. The conclusions are given according to the analysis and time simulation results.

  14. Scanning for oscillations

    Science.gov (United States)

    de Cheveigné, Alain; Arzounian, Dorothée

    2015-12-01

    Objective. Oscillations are an important aspect of brain activity, but they often have a low signal-to-noise ratio (SNR) due to source-to-electrode mixing with competing brain activity and noise. Filtering can improve the SNR of narrowband signals, but it introduces ringing effects that may masquerade as genuine oscillations, leading to uncertainty as to the true oscillatory nature of the phenomena. Likewise, time-frequency analysis kernels have a temporal extent that blurs the time course of narrowband activity, introducing uncertainty as to timing and causal relations between events and/or frequency bands. Approach. Here, we propose a methodology that reveals narrowband activity within multichannel data such as electroencephalography, magnetoencephalography, electrocorticography or local field potential. The method exploits the between-channel correlation structure of the data to suppress competing sources by joint diagonalization of the covariance matrices of narrowband filtered and unfiltered data. Main results. Applied to synthetic and real data, the method effectively extracts narrowband components at unfavorable SNR. Significance. Oscillatory components of brain activity, including weak sources that are hard or impossible to observe using standard methods, can be detected and their time course plotted accurately. The method avoids the temporal artifacts of standard filtering and time-frequency analysis methods with which it remains complementary.

  15. Nanoscale relaxation oscillator

    Science.gov (United States)

    Zettl, Alexander K.; Regan, Brian C.; Aloni, Shaul

    2009-04-07

    A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.

  16. Biological proton pumping in an oscillating electric field

    OpenAIRE

    Kim, Young C.; Furchtgott, Leon A.; Hummer, Gerhard

    2009-01-01

    Time-dependent external perturbations provide powerful probes of the function of molecular machines. Here we study biological proton pumping in an oscillating electric field. The protein cytochrome c oxidase is the main energy transducer in aerobic life, converting chemical energy into an electric potential by pumping protons across a membrane. With the help of master-equation descriptions that recover the key thermodynamic and kinetic properties of this biological “fuel cell,” we show that t...

  17. Quantum noise of a Michelson-Sagnac interferometer with translucent mechanical oscillator

    CERN Document Server

    Yamamoto, Kazuhiro; Westphal, Tobias; Gossler, Stefan; Danzmann, Karsten; Schnabel, Roman; Somiya, Kentaro; Danilishin, Stefan L

    2009-01-01

    Quantum fluctuations in the radiation pressure of light can excite stochastic motions of mechanical oscillators thereby realizing a linear quantum opto-mechanical coupling. When performing a precise measurement of the position of an oscillator, this coupling results in quantum radiation pressure noise. Up to now this effect has not been observed yet. Generally speaking, the strength of radiation pressure noise increases when the effective mass of the oscillator is decreased or when the power of the reflected light is increased. Recently, extremely light SiN membranes with high mechanical Q-values at room temperature have attracted attention as low thermal noise mechanical oscillators. However, the power reflectance of these membranes is much lower than unity which makes the use of advanced interferometer recycling techniques to amplify the radiation pressure noise in a standard Michelson interferometer inefficient. Here, we propose and theoretically analyze a Michelson-Sagnac interferometer that includes the ...

  18. A Clinical Study on the Effect of Yinxing Damo (银杏达莫) Combined with Betahistine Hydrochloride Injection on Vertebral Basilar Artery Ischemic Vertigo

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Objective: To evaluate the therapeutic efficacy of Yinxing Damo (银杏达莫, YXDM) combined with Betahistine Hydrochloride Injection (BHI) on vertebra basilar artery ischemic vertigo (VBIV).Methods: Ninety patients with VBIV were randomly divided into two groups; 45 patients (the treated group)were treated with YXDM and BHI intravenous dripping, once a day for 14 days. Another 45 patients (control clinical syndromes and the index of the transcranial Doppler (TCD) and hemorheology were observed. Results: The total effective rate was 100% in the treated group, which was better than that in the control group90.5%, (P<0.05). The indexes of TCD and hemorheology in the treated group were obviously improved after treatment, (P<0.01). Conclusion: YXDM combined with BHT injection had better effect in treating patients with VBIV is an ideal drug for VBIV.

  19. Physics of bubble oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Lauterborn, Werner; Kurz, Thomas [Third Physical Institute, University of Goettingen (Germany)

    2010-10-01

    Bubbles in liquids, soft and squeezy objects made of gas and vapour, yet so strong as to destroy any material and so mysterious as at times turning into tiny light bulbs, are the topic of the present report. Bubbles respond to pressure forces and reveal their full potential when periodically driven by sound waves. The basic equations for nonlinear bubble oscillation in sound fields are given, together with a survey of typical solutions. A bubble in a liquid can be considered as a representative example from nonlinear dynamical systems theory with its resonances, multiple attractors with their basins, bifurcations to chaos and not yet fully describable behaviour due to infinite complexity. Three stability conditions are treated for stable trapping of bubbles in standing sound fields: positional, spherical and diffusional stability. Chemical reactions may become important in that respect, when reacting gases fill the bubble, but the chemistry of bubbles is just touched upon and is beyond the scope of the present report. Bubble collapse, the runaway shrinking of a bubble, is presented in its current state of knowledge. Pressures and temperatures that are reached at this occasion are discussed, as well as the light emission in the form of short flashes. Aspherical bubble collapse, as for instance enforced by boundaries nearby, mitigates most of the phenomena encountered in spherical collapse, but introduces a new effect: jet formation, the self-piercing of a bubble with a high velocity liquid jet. Examples of this phenomenon are given from light induced bubbles. Two oscillating bubbles attract or repel each other, depending on their oscillations and their distance. Upon approaching, attraction may change to repulsion and vice versa. When being close, they also shoot self-piercing jets at each other. Systems of bubbles are treated as they appear after shock wave passage through a liquid and with their branched filaments that they attain in standing sound fields. The N

  20. Solar neutrino oscillation phenomenology

    Indian Academy of Sciences (India)

    Srubabati Goswami

    2004-02-01

    This article summarises the status of the solar neutrino oscillation phenomenology at the end of 2002 in the light of the SNO and KamLAND results. We first present the allowed areas obtained from global solar analysis and demonstrate the preference of the solar data towards the large-mixing-angle (LMA) MSW solution. A clear confirmation in favour of the LMA solution comes from the KamLAND reactor neutrino data. the KamLAND spectral data in conjunction with the global solar data further narrows down the allowed LMA region and splits it into two allowed zones - a low $ m^{2}$ region (low-LMA) and high $ m^{2}$ region (high-LMA). We demonstrate through a projected analysis that with an exposure of 3 kton-year (kTy) KamLAND can remove this ambiguity.

  1. Coronal Waves and Oscillations

    Directory of Open Access Journals (Sweden)

    Nakariakov Valery M.

    2005-07-01

    Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.

  2. Collective supernova neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Mirizzi, Alessandro [Max Planck Institute for Physics, Munich (Germany)

    2009-07-01

    Neutrinos emitted by core-collapse supernovae (SNe) represent an important laboratory for both particle physics and astrophysics. While propagating in the dense SN environment, they can feel not only the presence of background matter (via ordinary Mikheev-Smirnov-Wolfenstein effects) but also of the gas of neutrinos and antineutrinos (via neutrino-neutrino interaction effects). The neutrino-neutrino interactions appear to modify the flavor evolution of SN neutrinos in a collective way, completely different from the ordinary matter effects. In these conditions, the flavor evolution equations become highly nonlinear, sometimes resulting in surprising phenomena when the entire neutrino system oscillates coherently as a single collective mode. In this talk, I present the recent results on collective supernova neutrino flavor conversions and I discuss about the sensitivity of these effects to the ordering of the neutrino mass spectrum.

  3. Longitudinal oscillation of launch vehicles

    Science.gov (United States)

    Glaser, R. F.

    1973-01-01

    During powered flight a vehicle may develop longitudinal self-excited oscillations, so-called oscillations, of its structure. The energy supplying the vibration is tapped from the thrust by the activity of the system itself; that is, oscillation of the structure causes oscillation of the propellant system, especially of the pumps. In this way an oscillating thrust can be created that, by a feedback loop, may sustain the structural oscillation under certain circumstances. Two special features of the system proved to be essential for creation of instability. One is the effect of the inherent time interval that the thrust oscillation is lagging behind the structural oscillation. The other is the decreased of system mass caused by the exhausting of gas. The latter feature may cause an initially stable system to become unstable. To examine the stability of the system, a single mass-spring model, which is the result of a one-term Galerkin approach to the equation of motion, has been considered. The Nyquist stability criterion leads to a stability graph that shows the stability conditions in terms of the system parameter and also demonstrates the significance of time lag, feedback magnitude, and loss of mass. An important conclusion can be drawn from the analysis: large relative displacements of the pump-engine masses favor instability. This is also confirmed by flight measurements.

  4. Solar Neutrino Oscillation - An Overview

    CERN Document Server

    Roy, D P

    2005-01-01

    After a brief summary of the neutrino oscillation formalism and the solar neutrino sources and experiments I discuss the matter effect on solar neutrino oscillation. Then I discuss how the resulting alternative solutions are experimentally resolved in favour of the LMA solution, with particular exphasis on the SK, SNO and KL data.

  5. On The Harmonic Oscillator Group

    CERN Document Server

    Lopez, Raquel M; Vega-Guzman, Jose M

    2011-01-01

    We discuss the maximum kinematical invariance group of the quantum harmonic oscillator from a view point of the Ermakov-type system. The invariance group of generalized driven harmonic oscillator is shown to be isomorphic to the corresponding Schroedinger group of the free particle.

  6. 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...

  7. Lorentz violation and neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Mewes, Matthew [Marquette University, P.O. Box 1881, Milwaukee, WI 53201 (United States)

    2011-12-15

    Lorentz violation naturally leads to neutrino oscillations and provides an alternative mechanism that may explain current data. This contribution to the proceedings of The XXII International Conference on Neutrino Physics and Astrophysics provides a brief review of possible signals of Lorentz violation in neutrino-oscillation experiments.

  8. Neutrino Oscillations with Nil Mass

    CERN Document Server

    Floyd, Edward R

    2016-01-01

    An alternative neutrino oscillation process is presented as a counterexample for which the neutrino may have nil mass consistent with the standard model. The process is developed in a quantum trajectories representation of quantum mechanics, which has a Hamilton-Jacobi foundation. This process has no need for mass differences between mass eigenstates. Flavor oscillations and $\\bar{\

  9. Oscillator With Low Phase Noise

    Science.gov (United States)

    Kleinberg, Leonard L.

    1987-01-01

    Phase errors cancelled for high frequency stability. Radio-frequency oscillator achieves high stability of frequency through parallel, two-amplifier configuration in which effects cause phase noise tend to cancel each other. Circuit includes two amplifiers with resonating elements, each constitutes part of feedback loop of other. Generate same frequency because each circuit provides other with conditions necessary for oscillation.

  10. Hyperchaotic system with unstable oscillators

    DEFF Research Database (Denmark)

    Murali, K.; Tamasevicius, A.; Mykolaitis, G.;

    2000-01-01

    A simple electronic system exhibiting hyperchaotic behaviour is described. The system includes two nonlinearly coupled 2nd order unstable oscillators, each composed of an LC resonance loop and an amplifier. The system is investigated by means of numerical integration of appropriate differential e...... equations, PSPICE simulations and hardware experiments. The Lyapunov exponents are presented to confirm hyperchaotic mode of the oscillations....

  11. Mechanical Parametric Oscillations and Waves

    Science.gov (United States)

    Dittrich, William; Minkin, Leonid; Shapovalov, Alexander S.

    2013-01-01

    Usually parametric oscillations are not the topic of general physics courses. Probably it is because the mathematical theory of this phenomenon is relatively complicated, and until quite recently laboratory experiments for students were difficult to implement. However parametric oscillations are good illustrations of the laws of physics and can be…

  12. Coupled oscillators on evolving networks

    Science.gov (United States)

    Singh, R. K.; Bagarti, Trilochan

    2016-12-01

    In this work we study coupled oscillators on evolving networks. We find that the steady state behavior of the system is governed by the relative values of the spread in natural frequencies and the global coupling strength. For coupling strong in comparison to the spread in frequencies, the system of oscillators synchronize and when coupling strength and spread in frequencies are large, a phenomenon similar to amplitude death is observed. The network evolution provides a mechanism to build inter-oscillator connections and once a dynamic equilibrium is achieved, oscillators evolve according to their local interactions. We also find that the steady state properties change by the presence of additional time scales. We demonstrate these results based on numerical calculations studying dynamical evolution of limit-cycle and van der Pol oscillators.

  13. Photoacoustic elastic oscillation and characterization.

    Science.gov (United States)

    Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin

    2015-08-10

    Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ratio beyond optical absorption only, which is experimentally demonstrated in this paper.

  14. Photoacoustic elastic oscillation and characterization

    CERN Document Server

    Gao, Fei; Zheng, Yuanjin

    2014-01-01

    Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ra...

  15. Gravitational and dilaton radiation from a relativistic membrane

    CERN Document Server

    Galtsov, D V; Gal'tsov, Dmitri V.; Melkumova, Elena Yu.

    2001-01-01

    Recent scenarios of the TeV-scale brane cosmology suggest a possibility of existence in the early universe of two-dimensional topological defects: relativistic membranes. Like cosmic strings, oscillating membranes could emit gravitational radiation contributing to a stochastic background of gravitational waves. We calculate dilaton and gravitational radiation from a closed toroidal membrane excited along one homology cycle. The spectral-angular distributions of dilaton and gravitational radiation are obtained in a closed form in terms of Bessel's functions. The angular distributions are affected by oscillating factors due to an interference of radiation from different segments of the membrane. The dilaton radiation power is dominated by a few lower harmonics of the basic frequency, while the spectrum of the gravitational radiation contains also a substantial contribution from higher harmonics. The radiative lifetime of the membrane is determined by its tension and depends weakly on the ratio of two radii of t...

  16. 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.

  17. Polynomially deformed oscillators as k-bonacci oscillators

    CERN Document Server

    Gavrilik, A M

    2009-01-01

    A family of multi-parameter, polynomially deformed oscillators (PDOs) given by polynomial structure function \\phi(n) is studied from the viewpoint of being (or not) in the class of Fibonacci oscillators. These obey the Fibonacci relation/property (FR/FP) meaning that the n-th level energy E_n is given linearly, with real coefficients, by the two preceding ones E_{n-1}, E_{n-2}. We first prove that the PDOs do not fall in the Fibonacci class. Then, three different paths of generalizing the usual FP are developed for these oscillators: we prove that the PDOs satisfy respective k-term generalized Fibonacci (or "k-bonacci") relations; for these same oscillators we examine two other generalizations of the FR, the inhomogeneous FR and the "quasi-Fibonacci" relation. Extended families of deformed oscillators are studied too: the (q;\\mu)-oscillator with \\phi(n) quadratic in the basic q-number [n]_q is shown to be Tribonacci one, while the (p,q;\\mu)-oscillators with \\phi(n) quadratic (cubic) in the p,q-number [n]_{p,q...

  18. A New Theory of Oscillating Flows

    Science.gov (United States)

    Vladimirov, Vladimir

    2010-11-01

    A new theory of viscous oscillatory flows has been developed. Our theory represents an adaptation of the Vishik-Lyusternik approach combined with the two-timing and averaging methods. We consider the high Re viscous incompressible flows driven by a vibrating boundary for the simple geometry of a half-space. From the physical viewpoint the considered boundary conditions may be seen as the tangential vibrations of material points of a plane stretchable membrane. The main result is the obtaining of the general, global, and uniformly valid asymptotic solutions of the Navier-Stokes equations. These solutions satisfy general oscillating boundary conditions and three different settings of the scaling parameters (that correspond to the strong, moderate, and weak nonlinearities). We have derived that the streaming part of any solution is governed by either the full Navier-Stokes equations or Stokes' equations (both with the unit Re) as well as by the precisely derived effective boundary conditions. The examples of the spatially periodic vibrations of the boundary and the angular torsional vibrations of an infinite rigid disc have been considered. In the sharp contrast to all previous theories of oscillating flows (see e.g. Batchelor's "Introduction to fluid dynamics," formula 5.13.15) our solutions do not deal with any secular (infinitely growing with the inner normal coordinate) terms. This new approach may be seen as a revolutionary step in the field, since for the very first time it does not use the asymptotic matching procedures and the boundary layer theories.

  19. Stochastic switching between multistable oscillation patterns of the Min-system

    CERN Document Server

    Amiranashvili, Artemij; Schwarz, Ulrich S

    2016-01-01

    The spatiotemporal oscillation patterns of the proteins MinD and MinE are used by the bacterium E. coli to sense its own geometry. Strikingly, both computer simulations and experiments have recently shown that for the same geometry of the reaction volume, different oscillation patterns can be stable, with stochastic switching between them. Here we use particle-based Brownian dynamics simulations to predict the relative frequency of different oscillation patterns over a large range of three-dimensional compartment geometries, in excellent agreement with experimental results. Fourier analyses as well as pattern recognition algorithms are used to automatically identify the different oscillation patterns and the switching rates between them. We also identify novel oscillation patterns in three-dimensional compartments with membrane-covered walls and identify a linear relation between the bound Min-protein densities and the volume-to-surface ratio. In general, our work shows how geometry sensing is limited by mult...

  20. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    , Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual examination...

  1. A theory of generalized Bloch oscillations.

    Science.gov (United States)

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

    2016-04-20

    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.

  2. Longitudinally propagating traveling waves of the mammalian tectorial membrane.

    Science.gov (United States)

    Ghaffari, Roozbeh; Aranyosi, Alexander J; Freeman, Dennis M

    2007-10-16

    Sound-evoked vibrations transmitted into the mammalian cochlea produce traveling waves that provide the mechanical tuning necessary for spectral decomposition of sound. These traveling waves of motion that have been observed to propagate longitudinally along the basilar membrane (BM) ultimately stimulate the mechano-sensory receptors. The tectorial membrane (TM) plays a key role in this process, but its mechanical function remains unclear. Here we show that the TM supports traveling waves that are an intrinsic feature of its visco-elastic structure. Radial forces applied at audio frequencies (2-20 kHz) to isolated TM segments generate longitudinally propagating waves on the TM with velocities similar to those of the BM traveling wave near its best frequency place. We compute the dynamic shear storage modulus and shear viscosity of the TM from the propagation velocity of the waves and show that segments of the TM from the basal turn are stiffer than apical segments are. Analysis of loading effects of hair bundle stiffness, the limbal attachment of the TM, and viscous damping in the subtectorial space suggests that TM traveling waves can occur in vivo. Our results show the presence of a traveling wave mechanism through the TM that can functionally couple a significant longitudinal extent of the cochlea and may interact with the BM wave to greatly enhance cochlear sensitivity and tuning.

  3. Forced synchronization of quasiperiodic oscillations

    Science.gov (United States)

    Stankevich, N. V.; Kurths, J.; Kuznetsov, A. P.

    2015-01-01

    A model of a generator of quasiperiodic oscillations forced by a periodic pulse sequence is studied. We analyze synchronization when the autonomous generator demonstrates periodic, quasiperiodic, respective weakly chaotic oscillations. For the forced quasiperiodic oscillations a picture of synchronization, consisting of small-scale and large-scale structures was uncovered. It even includes the existence of stable the three-frequency tori. For the regime of weak chaos a partial destruction of this features and of the regime of three-frequency tori are found.

  4. Collective oscillations in a plasma

    CERN Document Server

    Akhiezer, A I; Polovin, R V; ter Haar, D

    2013-01-01

    International Series of Monographs in Natural Philosophy: Collective Oscillations in a Plasma, Volume 7 presents specific topics within the general field of radio waves propagation. This book contains five chapters that address the theory of linear oscillations in a plasma, the spectra of the eigen oscillations, and the mechanism of high-frequency heating. The opening chapters deal with the self-consistent fields; development of initial perturbation; dispersion permittivity tensor of a plasma in a magnetic field; effect of thermal motion of particles on low-frequency resonances; excitation of

  5. Oscillating solitons in nonlinear optics

    Indian Academy of Sciences (India)

    Lin Xiao-Gang; Liu Wen-Jun; Lei Ming

    2016-03-01

    Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota’s bilinear method. The bilinear forms and analytic soliton solutions are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers.

  6. Gravitational Wave - Gauge Field Oscillations

    CERN Document Server

    Caldwell, R R; Maksimova, N A

    2016-01-01

    Gravitational waves propagating through a stationary gauge field transform into gauge field waves and back again. When multiple families of flavor-space locked gauge fields are present, the gravitational and gauge field waves exhibit novel dynamics. At high frequencies, the system behaves like coupled oscillators in which the gravitational wave is the central pacemaker. Due to energy conservation and exchange among the oscillators, the wave amplitudes lie on a multi-dimensional sphere, reminiscent of neutrino flavor oscillations. This phenomenon has implications for cosmological scenarios based on flavor-space locked gauge fields.

  7. Fission waves can oscillate

    CERN Document Server

    Osborne, Andrew G

    2016-01-01

    Under the right conditions, self sustaining fission waves can form in fertile nuclear materials. These waves result from the transport and absorption of neutrons and the resulting production of fissile isotopes. When these fission, additional neutrons are produced and the chain reaction propagates until it is poisoned by the buildup of fission products. It is typically assumed that fission waves are soliton-like and self stabilizing. However, we show that in uranium, coupling of the neutron field to the 239U->239Np->239Pu decay chain can lead to a Hopf bifurcation. The fission reaction then ramps up and down, along with the wave velocity. The critical driver for the instability is a delay, caused by the half-life of 239U, between the time evolution of the neutron field and the production of 239Pu. This allows the 239Pu to accumulate and burn out in a self limiting oscillation that is characteristic of a Hopf bifurcation. Time dependent results are obtained using a numerical implementation of a reduced order r...

  8. Oscillations in Mathematical Biology

    CERN Document Server

    1983-01-01

    The papers in this volume are based on talks given at a one day conference held on the campus of Adelphi University in April 1982. The conference was organized with the title "Oscillations in Mathematical Biology;" however the speakers were allowed considerable latitutde in their choice of topics. In the event, the talks all concerned the dynamics of non-linear systems arising in biology so that the conference achieved a good measure of cohesion. Some of the speakers cho~e not to submit a manuscript for these proceedings, feeling that their material was too conjectural to be committed to print. Also the paper of Rinzel and Troy is a distillation of the two separate talks that the authors gave. Otherwise the material reproduces the conference proceedings. The conference was made possible by the generous support of the Office of the Dean of the College of Arts and Sciences at Adelphi. The bulk of the organization of the conference was carried out by Dr. Ronald Grisell whose energy was in large measure responsib...

  9. Chromosome oscillations in mitosis

    Science.gov (United States)

    Campas, Otger

    2008-03-01

    Successful cell division necessitates a tight regulation of chromosome movement via the activity of molecular motors. Many of the key players at the origin of the forces generating the motion have been identified, but their spatial and temporal organization remains elusive. In animal cells, chromosomes periodically switch between phases of movement towards and away from the pole. This characteristic oscillatory behaviour cannot be explained by the current models of chromosome positioning and congression. We perform a self-contained theoretical analysis in which the motion of mono-oriented chromosomes results from the competition between the activity of the kinetochore and chromokinesin motors on the chromosome arms. Our analysis, consistent with the available experimental data, proposes that the interplay between the aster-like morphology of the spindle and the collective kinetics of molecular motors is at the origin of chromosome oscillations, positioning and congression. It provides a natural explanation for the so-called chromosome directional instability and for the mechanism by which chromosomes sense their position in space. In addition, we estimate the in vivo velocity of chromokinesins at vanishing load and propose new experiments to assess the mechanism at the origin of chromosome movement in cell division.

  10. Quantum superposition, entanglement, and state teleportation of a microorganism on an electromechanical oscillator

    CERN Document Server

    Li, Tongcang

    2016-01-01

    Schr\\"odinger's thought experiment to prepare a cat in a superposition of both alive and dead states reveals profound consequences of quantum mechanics and has attracted enormous interests. Here we propose a straightforward method to create quantum superposition states of a living microorganism by putting a small bacterium on top of an electromechanical oscillator. Our proposal is based on recent developments that the center-of-mass oscillation of a 15-$\\mu$m-diameter aluminium membrane has been cooled to its quantum ground state [Nature 475, 359 (2011)], and entangled with a microwave field [Science, 342, 710 (2013)]. A microorganism with a mass much smaller than the mass of the electromechanical membrane will not significantly affect the quality factor of the membrane and can be cooled to the quantum ground state together with the membrane. Quantum superposition and teleportation of its center-of-mass motion state can be realized with the help of superconducting microwave circuits. More importantly, the int...

  11. Gamma Oscillations and Visual Binding

    Science.gov (United States)

    Robinson, Peter A.; Kim, Jong Won

    2006-03-01

    At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.

  12. Matrix Theory of Small Oscillations

    Science.gov (United States)

    Chavda, L. K.

    1978-01-01

    A complete matrix formulation of the theory of small oscillations is presented. Simple analytic solutions involving matrix functions are found which clearly exhibit the transients, the damping factors, the Breit-Wigner form for resonances, etc. (BB)

  13. Global Analysis of Neutrino Oscillation

    CERN Document Server

    Goswami, S; Choubey, S; Goswami, Srubabati; Bandyopadhyay, Abhijit; Choubey, Sandhya

    2005-01-01

    We present the constraints on neutrino oscillation parameters $\\Delta m^2_{\\odot}$ and $\\theta_{\\odot}$ governing the solar neutrino oscillations from two generation analysis of solar and KamLAND data. We include the latest 766.3 ton year KamLAND data in our analysis. We also present the allowed values of parameters $\\Delta m^2_{atm}$ and $\\sin^2\\theta_{atm}$ from two generation oscillation analysis of SuperKamiokande atmospheric and K2K data. For both cases we discuss the precision achieved in the present set of experiments and also how the precision can be improved in future. We also obtain the bounds on $\\theta_{13}$ from three generation analysis of global oscillation data. We emphasise on the roles played by different data sets in constraining the allowed parameter ranges.

  14. Global Analysis of Neutrino Oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Goswami, Srubabati [Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211 019 (India); Bandyopadhyay, Abhijit [Theory Group, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Calcutta 700 064 (India); Choubey, Sandhya [INFN, Sezione di Trieste and Scuola Internazionale Superiore di Studi Avanzati, I-34014, Trieste (Italy)

    2005-06-15

    We present the constraints on neutrino oscillation parameters {delta}m{sub -}bar {sup 2} and {theta}{sub -}bar governing the solar neutrino oscillations from two generation analysis of solar and KamLAND data. We include the latest 766.3 ton year KamLAND data in our analysis. We also present the allowed values of parameters {delta}m{sub atm}{sup 2} and sin{sup 2}{theta}{sub atm} from two generation oscillation analysis of SuperKamiokande atmospheric and K2K data. For both cases we discuss the precision achieved in the present set of experiments and also how the precision can be improved in future. We also obtain the bounds on {theta}{sub 13} from three generation analysis of global oscillation data. We emphasise on the roles played by different data sets in constraining the allowed parameter ranges.

  15. Strongly nonlinear oscillators analytical solutions

    CERN Document Server

    Cveticanin, Livija

    2014-01-01

    This book provides the presentation of the motion of pure nonlinear oscillatory systems and various solution procedures which give the approximate solutions of the strong nonlinear oscillator equations. The book presents the original author’s method for the analytical solution procedure of the pure nonlinear oscillator system. After an introduction, the physical explanation of the pure nonlinearity and of the pure nonlinear oscillator is given. The analytical solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter is considered. Special attention is given to the one and two mass oscillatory systems with two-degrees-of-freedom. The criteria for the deterministic chaos in ideal and non-ideal pure nonlinear oscillators are derived analytically. The method for suppressing chaos is developed. Important problems are discussed in didactic exercises. The book is self-consistent and suitable as a textbook for students and also for profess...

  16. Matter Effects On Neutrino Oscillations

    Science.gov (United States)

    Gordon, Michael

    An introduction to neutrino oscillations in vacuum is presented, followed by a survey of various techniques for obtaining either exact or approximate expressions for numu → nue oscillations in matter. The method developed by Arafune, Koike, and Sato uses a perturbative analysis to find an approximation for the evolution operator. The method used by Freund yields an approximate oscillation probability by diagonalizing the Hamiltonian, finding the eigenvalues and eigenvectors, and then using those to find modified mixing angles with the matter effect taken into account. The method devised by Mann, Kafka, Schneps, and Altinok produces an exact expression for the oscillation by determining explicitly the evolution operator. These methods are compared to each other using the T2K, MINOS, NOnuA, and LBNE parameters.

  17. Atmospheric Neutrino Oscillations in Antares

    Energy Technology Data Exchange (ETDEWEB)

    Brunner, J.

    2013-04-15

    The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximum mixing, a mass difference of Δm{sub 32}{sup 2}=(3.1±0.9)⋅10{sup −3}eV{sup 2} is obtained, in good agreement with the world average value.

  18. Oscillations of thick accretion discs

    Energy Technology Data Exchange (ETDEWEB)

    Jaroszynski, M.

    1986-06-15

    The non-axisymmetric oscillations of polytropic, ideal fluid tori rotating in the external gravitational field of a point mass are investigated both numerically and analytically. Normal modes of oscillations are found; their classification into 'radial', 'p', 'g' and 'f' modes is done in analogy to the stellar case. The non-discrete spectrum of modes which are neutral in the limit of axisymmetric perturbations is also present.

  19. Harmonic Oscillators and Elementary Particles

    CERN Document Server

    Sobouti, Y

    2016-01-01

    Two dynamical systems with same symmetry should have features in common, and as far as their shared symmetry is concerned, one may represent the other. The three light quark constituents of the hadrons, a) have an approximate flavor SU(3) symmetry, b) have an exact color SU(3) symmetry, and c) as spin 1/2 particles, have a Lorentz SO(3,1) symmetry. So does a 3D harmonic oscillator. a) Its Hamiltonian has the SU(3) symmetry, breakable if the 3 fundamental modes of oscillation are not identical. b) The 3 directions of oscillation have the permutation symmetry. This enables one to create three copies of unbreakable SU(3) symmetry for each mode of the oscillation, and mimic the color of the elementary particles. And c) The Lagrangian of the 3D oscillator has the SO(3,1) symmetry. This can be employed to accommodate the spin of the particles. In this paper we draw up a one-to-one correspondence between the eigen modes of the Poisson bracket operator of the 3D oscillator and the flavor multiplets of the particles, ...

  20. Chiari畸形合并颅底凹陷的外科手术治疗%Surgical treatment of Chiari malformation complicated with basilar impression

    Institute of Scientific and Technical Information of China (English)

    马原; 贺伟旗; 程林; 卢敏; 顾建文; 匡永勤; 夏勋; 杨立斌; 张俊海; 程敬民; 杨涛; 黄海东

    2011-01-01

    目的 探讨小骨窗后颅窝减压加枕颈植骨融合内固定术治疗Chiari畸形合并颅底凹陷的手术效果.方法 回顾性分析2006-2010年收治的16例Chiari畸形合并颅底凹陷患者,其中男7例,女9例,年龄17~65岁,平均36.4岁.所有患者均经影像学确诊,手术采取小骨窗后颅窝减压,小脑扁桃体切除,一期取自体髂骨行颈枕植骨融合钢丝内固定,术后行颈托固定3个月.结果 所有患者术后症状均明显改善,无感染或死亡,1例出现引流口脑脊液漏,1例出现一过性肩胛区和胸胁部疼痛,未经治疗自行消失.术后随访6个月,按Symon和Lavender临床标准,治愈6例,好转9例,无效1例.复查MRI显示重建枕大池清晰,无小脑下垂发生,植骨已融合. 结论小骨窗后颅窝减压加枕颈植骨融合钢丝内固定术治疗Chiari畸形合并颅底凹陷效果确切,在增加后颅窝容积同时可减轻脑干腹侧受压,并能重建颅颈交界区稳定性.%Objective To evaluate the therapeutic effect of small craniotomic posterior fossa decompression combined with occipitalcervical bone graft fusion and internal fixation on Chiari malformation complicated with basilar impression. Methods The clinical data of 16 cases (7 males and 9 females, aged 17 to 65 years, mean 36. 4) of Chiari malformation complicated with basilar impression from 2006 to 2010 were retrospectively analyzed. The diagnoses for all the patients were confirmed by radiology. Small craniotomic posterior fossa decompression was performed in all patients, cerebellar tonsils were resected, and then one-stage occipital-cervical bone graft fusion using autogenous iliac bone and internal wiring fixation were performed. Neck support was used for 3 months after surgery. Results Symptoms were significantly improved in all cases after surgical operation. No patient died or infected. Cerebrospinal fluid leakage was found at draining site in one case. Transient pain of scapular and chest was found

  1. 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…

  2. On the nonlinear modeling of ring oscillators

    KAUST Repository

    Elwakil, Ahmed S.

    2009-06-01

    We develop higher-order nonlinear models of three-stage and five-stage ring oscillators based on a novel inverter model. The oscillation condition and oscillation frequency are derived and compared to classical linear model analysis. Two important special cases for five-stage ring oscillators are also studied. Numerical simulations are shown. © 2009 World Scientific Publishing Company.

  3. A theory of generalized Bloch oscillations

    DEFF Research Database (Denmark)

    Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny;

    2016-01-01

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact cal...... oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics.......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...

  4. 高压氧治疗基底型偏头痛的临床研究%Clinical research on treating basilar migraine with hyperbaric oxygen

    Institute of Scientific and Technical Information of China (English)

    谷松; 过伟峰

    2014-01-01

    Objective:To observe the curative effect and discuss the mechanism of hyperbaric oxygen on treating basilar migraine. Methods: 65 patients with basilar migraine were randomly divided into the treatment group (n=33) and the control group (n=32) by random number table. Patients in the treatment group were treated by sealed pressure cabin, 0.2 MPa(2.0ATA)for 65min, and mask absorbing pure oxygen for 30min×2, absorbing air for 5min and depressurization for 25min, once daily. Patients in the control group were given orally 10mg flunarizine hydrochloride before sleeping. The curative effects were compared for 10 days, a course of treatment. Results:I Before treatment, there was no significant difference in VAS, VRS and non-painful duration between the two groups (P>0.05); After treatment, VAS and VRS reduced obviously in the two groups (P0.05);After treatment, Vs, Vm and Vd increased in both, and it was clearer in the treatment group (P0.05),治疗后两组 VAS、VRS 均较治疗前明显降低(P0.05);治疗后两组BA的Vs、Vm、Vd均有增加,并且治疗组(P<0.01)改善的程度比对照组(P<0.05)明显,治疗组 PI 明显下降;两组治疗后比较,差异具有明显统计学意义(P<0.01)。结论:两组治疗方法均能够显著改善基底型偏头痛患者发作时头痛程度及发作频度,改善患者基底动脉的血流速度及搏动指数,且高压氧治疗优于药物治疗。高压氧治疗基底型偏头痛有效,其机理之一可能为高压氧能够抑制炎性介质及血小板释放,增加基底动脉供血。

  5. Distribuição do contraste em angiografias cerebrais: I - Angiografias carotídeas com enchimento do tronco basilar

    Directory of Open Access Journals (Sweden)

    José Zaclis

    1957-06-01

    Full Text Available A propósito da passagem de contraste, nas angiografias por via carotídea, para vasos não pertencentes ao território de distribuição da artéria na qual o contraste foi injetado, foi feita uma revisão de 700 angiografias. O segmento pós-comunicante da artéria cerebral posterior ipsilateral foi encontrado em 42,5% dos casos; o segmento pós-comunicante da artéria cerebral anterior contralateral apareceu em 49,4%; maior ou menor extensão do segmento pré-comunicante da artéria cerebral anterior do lado oposto foi encontrada em 9,85%; a artéria cerebral média bem como o segmento pré-comunicante da cerebral anterior do lado oposto foram encontrados em 4,85% dos casos. A freqüência da visibilização de outras artérias não pertencentes ao território do vaso no qual o contraste foi injetado pode ser fàcilmente verificada no quadro 1. O motivo principal desta publicação foi dado por um grupo de 22 angiografias, nas quais o contraste, injetado por via carotídea, penetrou também no sistema vértebro-basilar. O fato verificado nestas 22 angiografias cerebrais tem sido relatado raramente. Da discussão do mecanismo pelo qual o contraste penetra no tronco basilar, chegando mesmo, por vêzes, até às artérias vertebrais, resultou uma hipótese segundo a qual o fenômeno seria condicionado por hipotensão arterial, acentuada, mas passageira, produzida por um reflexo hiperativo do seio carotídeo provocado pela própria injeção do contraste. Se fôr comprovada esta hipótese, a demonstração angiográfica de todo o sistema arterial encefálico com uma só injeção de contraste por via carotídea poderá ser viável, deliberadamente, empregando hipotensão induzida e controlada.

  6. Complex Dynamics of Nano-Mechanical Membrane in Cavity Optomechanics

    CERN Document Server

    Akram, Muhammad Javed

    2016-01-01

    Theoretical analysis of a suspended nano-mechanical membrane subject to an optical driving field in cavity optomechanics is presented, which is confirmed through numerical simulations. In the presence of an optical field between its mirrors a high finesse nano-mechanical resonator acts as an oscillator driven by radiation pressure force. The periodic nature of the radiation pressure force makes the nano-mechanical membrane in the optomechanical system as kicked harmonic oscillator. Mathematically the physical system displays a stochastic web map that helps to understand several properties of the kicked membrane in classical phase space. We find that our web map is area preserving, and displays quasi-periodic symmetrical structures in phase space which we express as q-fold symmetry. It is shown that under appropriate control of certain parameters, namely the frequency ratio (q) and the kicking strength (K), the dynamics of kicked membrane exhibits chaotic dynamics. We provide the stability analysis by means of...

  7. Regulation Mechanisms of Stomatal Oscillation

    Institute of Scientific and Technical Information of China (English)

    Hui-Min YANG; Jian-Hua ZHANG; Xiao-Yan ZHANG

    2005-01-01

    Stomata function as the gates between the plant and the atmospheric environment. Stomatal movement, including stomatal opening and closing, controls CO2 absorption as the raw material for photosynthesis and water loss through transpiration. How to reduce water loss and maintain enough CO2 absorption has been an interesting research topic for some time. Simple stomatal opening may elevate CO2 absorption,but, in the meantime, promote the water loss, whereas simple closing of stomatal pores may reduce both water loss and CO2 absorption, resulting in impairment of plant photosynthesis. Both processes are not economical to the plant. As a special rhythmic stomatal movement that usually occurs at smaller stomatal apertures, stomatal oscillation can keep CO2 absorption at a sufficient level and reduce water loss at the same time, suggesting a potential improvement in water use efficiency. Stomatal oscillation is usually found after a sudden change in one environmental factor in relatively constant environments. Many environmental stimuli can induce stomatal oscillation. It appears that, at the physiological level, feedback controls are involved in stomatal oscillation. At the cellular level, possibly two different patterns exist: (i) a quicker responsive pattern; and (ii) a slower response. Both involve water potential changes and water channel regulation, but the mechanisms of regulation of the two patterns are different. Some evidence suggests that the regulation of water channels may play a vital and primary role in stomatal oscillation. The present review summarizes studies on stomatal oscillation and concludes with some discussion regarding the mechanisms of regulation of stomatal oscillation.

  8. El Nino Southern Oscillation as Sporadic Oscillations between Metastable States

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The main objective of this article is to establish a new mechanism of ENSO,as a self-organizing and self-excitation system,with two highly coupled processes.The first is the oscillation between the two metastable warm(El Ni(?)o phase) and cold events(La Ni(?)a phase),and the second is the spatiotemporal oscillation of the sea surface temperature(SST) field.The symbiotic interplay between these two processes gives rises the climate variability associated with the ENSO,leads to both the random and deterministic features of the ENSO,and defines a new natural feedback mechanism,which drives the sporadic oscillation of the ENSO.The new mechanism is rigorously derived using a dynamic transition theory developed recently by the authors,which has also been successfully applied to a wide range of problems in nonlinear sciences.

  9. El Nino Southern Oscillation as Sporadic Oscillations between Metastable States

    Institute of Scientific and Technical Information of China (English)

    MA Tian; Shouhong WANG

    2011-01-01

    The main objective of this article is to establish a new mechanism of ENSO, as a self-organizing and selfexcitation system, with two highly coupled processes. The first is the oscillation between the two mctastable warm (El Nino phase) and cold events (La Nina phase), and the second is the spatiotemporal oscillation of the sea surface temperature (SST) field. The symbiotic interplay between these two processes gives rises the climate variability associated with the ENSO, leads to both the random and deterministic features of the ENSO, and defines a new natural feedback mechanism, which drives the sporadic oscillation of the ENSO. The new mechanism is rigorously derived using a dynamic transition theory developed recently by the authors, which has also been successfully applied to a wide range of problems in nonlinear sciences.

  10. Oscillations in glycolysis in Saccharomyces cerevisiae: the role of autocatalysis and intracellular ATPase activity.

    Science.gov (United States)

    Kloster, Antonina; Olsen, Lars Folke

    2012-05-01

    We have investigated the glycolytic oscillations, measured as NADH autofluorescence, in the yeast Saccharomyces cerevisiae in a batch reactor. Specifically, we have tested the effect of cell density and a number of inhibitors or activators of ATPase activity on the amplitude of the oscillations. The amplitude dependence on cell density shows the same behavior as that observed in cells in a CSTR. Furthermore, the amplitude decreases with increasing inhibition of the three ATPases (i) F(0)F(1) ATPase, (ii) plasma membrane ATPase (Pma1p) and (iii) vacuolar ATPase (V-ATPase). The amplitude of the oscillations also decreases by stimulating the ATPase activity, e.g. by FCCP or Amphotericin B. Thus, ATPase activity strongly affects the glycolytic oscillations. We discuss these data in relation to a simple autocatalytic model of glycolysis which can reproduce the experimental data and explain the role of membrane-bound ATPases . In addition we also studied a recent detailed model of glycolysis and found that, although this model faithfully reproduces the oscillations of glycolytic intermediates observed experimentally, it is not able to explain the role of ATPase activity on the oscillations.

  11. Particle-based model of Min-protein oscillations in Escherichia coli

    Science.gov (United States)

    Berman, Adam; Huang, Kerwyn; Wingreen, Ned

    2007-03-01

    In Escherichia coli cells, the Min proteins, which are required for division site selection, oscillate from pole to pole via a Turing instability. During these oscillations, two of the Min proteins, MinD and MinE self-associate and co- associate on the bacterial inner membrane forming dynamic structures including a ring of MinE protein, compact polar zones of MinD, and zebra stripes in filamentous cells. Such rich behavior in a system with so few species has made the Min proteins a model system for applying computational methods to study intracellular dynamics in bacteria. Though mean-field computational models successfully reproduce the coarse-grained oscillatory dynamics in both rod-shaped and round E. coli cells and also predict that the Min-proteins actively detect cell shape, the mean-field models cannot address questions raised by the recent finding that MinD forms a small number of large polymers on the membrane. First, it is unclear how the intrinsic dynamics of polymer formation, namely polymer nucleation and growth, affect the pole-to-pole oscillations. Second, it is not understood how the oscillations influence the morphology of the MinD polymers. To study this coupling between MinD polymerization and pole-to-pole oscillation, we employ a particle-based computational model. In this talk, we will describe this model, which produces both large polymers and pole-to-pole oscillations.

  12. Arrays of coupled chemical oscillators

    CERN Document Server

    Forrester, Derek Michael

    2016-01-01

    Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a "worship". Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In ...

  13. ALG-2 oscillates in subcellular localization, unitemporally with calcium oscillations

    DEFF Research Database (Denmark)

    la Cour, Jonas Marstrand; Mollerup, Jens; Berchtold, Martin Werner

    2007-01-01

    localization in an oscillatory fashion unitemporally with Ca2+ oscillations, whereas a Ca2+-binding deficient mutant of ALG-2 did not redistribute. Using tagged ALG-2 as bait we identified its novel target protein Sec31A and based on the partial colocalization of endogenous ALG-2 and Sec31A we propose that ALG......A variety of stimuli can trigger intracellular calcium oscillations. Relatively little is known about the molecular mechanisms decoding these events. We show that ALG-2, a Ca2+-binding protein originally isolated as a protein associated with apoptosis, is directly linked to Ca2+ signalling. We...

  14. Minimally Invasive Treatment of Biventricular Hydrocephalus Caused by a Giant Basilar Apex Aneurysm via a Staged Combination of Endoscopy and Endovascular Embolization: A Case Report.

    Science.gov (United States)

    Setty, Pradeep; Volkov, Andrey; Richards, Boyd; Barrett, Ryan

    2015-01-01

    Biventricular hydrocephalus caused by a Giant Basilar Apex Aneurysm (GBAA) is a rare finding that presents unique and challenging treatment decisions. We report a case of GBAA causing a life-threatening biventricular hydrocephalus in which both the aneurysm and hydrocephalus were given definitive treatment through a staged, minimally invasive approach. An obtunded 82-year-old male was found to have biventricular hydrocephalus caused by an unruptured GBAA obstructing the foramina of Monro. The patient was treated via staged, minimally invasive technique that first involved endoscopic fenestration of the septum pellucidum to create communication between the lateral ventricles. A programmable ventriculo-peritoneal shunt was then placed with a high-pressure setting. The patient was then loaded with dual anti-platelet therapy prior to undergoing endovascular coiling of the GBAA with adjacent stenting of the Posterior Cerebral Artery. He remained on dual anti-platelet therapy and the shunt setting was lowered at the bedside to treat the hydrocephalus. At 6-month follow up, the patient had returned to his cognitive baseline, speaking fluently and appropriately. Biventricular hydrocephalus caused by a GBAA can successfully be treated in a minimally invasive fashion utilizing a combination of endoscopy and endovascular therapy, even when a stent-assisted coiling is needed.

  15. Bloch oscillations in carbon nanotubes.

    Science.gov (United States)

    Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.

  16. Classical scattering from oscillating targets

    Energy Technology Data Exchange (ETDEWEB)

    Papachristou, P.K.; Diakonos, F.K.; Constantoudis, V.; Schmelcher, P.; Benet, L

    2002-12-30

    We study planar classical scattering from an oscillating heavy target whose dynamics defines a five-dimensional phase space. Although the system possesses no periodic orbits, and thus topological chaos is not present, the scattering functions display a variety of structures on different time scales. These structures are due to scattering events with a strong energy transfer from the projectile to the moving disk resulting in low-velocity peaks. We encounter initial conditions for which the projectile exhibits infinitely many bounces with the oscillating disk. Our numerical investigations are supported by analytical results on a specific model with a simple time-law. The observed properties possess universal character for scattering off oscillating targets.

  17. Prediction of pilot induced oscillations

    Directory of Open Access Journals (Sweden)

    Valentin PANĂ

    2011-03-01

    Full Text Available An important problem in the design of flight-control systems for aircraft under pilotedcontrol is the determination of handling qualities and pilot-induced oscillations (PIO tendencieswhen significant nonlinearities exist in the vehicle description. The paper presents a method to detectpossible pilot-induced oscillations of Category II (with rate and position limiting, a phenomenonusually due to a misadaptation between the pilot and the aircraft response during some tasks in whichtight closed loop control of the aircraft is required from the pilot. For the analysis of Pilot in the LoopOscillations an approach, based on robust stability analysis of a system subject to uncertainparameters, is proposed. In this analysis the nonlinear elements are substituted by linear uncertainparameters. This approach assumes that PIO are characterized by a limit cycle behavior.

  18. Bloch oscillations in carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Jodar, Esther; Perez-Garrido, Antonio [Departamento Fisica Aplicada, Antiguo Hospital de Marina Campus Muralla del Mar, UPCT, Cartagena 30202 Murcia (Spain); Rojas, Fernando [Centro de Nanociencias y Nanotecnologia-UNAM, Apartado Postal 356, Ensenada, Baja California 22800 (Mexico)], E-mail: ejodar@upct.es

    2009-05-27

    Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case. (fast track communication)

  19. Magnetically insulated transmission line oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Bacon, Larry D. (Albuquerque, NM); Ballard, William P. (Albuquerque, NM); Clark, M. Collins (Albuquerque, NM); Marder, Barry M. (Albuquerque, NM)

    1988-01-01

    A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.

  20. Numerical bifurcation analysis of two coupled FitzHugh-Nagumo oscillators

    CERN Document Server

    Hoff, Anderson; Manchein, Cesar; Albuquerque, Holokx A

    2015-01-01

    The behavior of neurons can be modeled by the FitzHugh-Nagumo oscillator model, consisting of two nonlinear differential equations, which simulates the behavior of nerve impulse conduction through the neuronal membrane. In this work, we numerically study the dynamical behavior of two coupled FitzHugh-Nagumo oscillators. We consider unidirectional and bidirectional couplings, for which Lyapunov and isoperiodic diagrams were constructed calculating the Lyapunov exponents and the number of the local maxima of a variable in one period interval of the time-series, respectively. By numerical continuation method the bifurcation curves are also obtained for both couplings. The dynamics of the networks here investigated are presented in terms of the variation between the coupling strength of the oscillators and other parameters of the system. For the network of two oscillators unidirectionally coupled, the results show the existence of Arnold tongues, self-organized sequentially in a branch of a Stern-Brocot tree and ...

  1. The non-local oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Maccari, A. [Istituto Tecnico `G. Cardano`, Monterotondo, Rome (Italy)

    1996-08-01

    The most important characteristics of the non-local oscillator, an oscillator subjected to an additional non-local force, are extensively studied by means of a new asymptotic perturbation method that is able to furnish an approximate solution of weakly non-linear differential equations. The resulting motion is doubly periodic, because a second little frequency appears, in addition to the fundamental harmonic frequency. Comparison with the numerical solution obtained by the Runge-Kitta method confirms the validity of the asymptotic perturbation method and its importance for the study of non-linear dynamical systems.

  2. Sound oscillation of dropwise cluster

    Science.gov (United States)

    Shavlov, A. V.; Dzhumandzhi, V. A.; Romanyuk, S. N.

    2012-06-01

    There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60-100 °C. The charge of drops reaches 102-103 units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method.

  3. Cherenkov radiation oscillator without reflectors

    Science.gov (United States)

    Li, D.; Wang, Y.; Hangyo, M.; Wei, Y.; Yang, Z.; Miyamoto, S.

    2014-05-01

    This Letter presents a Cherenkov radiation oscillator with an electron beam travelling over a finitely thick plate made of negative-index materials. In such a scheme, the external reflectors required in the traditional Cherenkov oscillators are not necessary, since the electromagnetic energy flows backward in the negative-index materials, leading to inherent feedback. We theoretically analyzed the interaction between the electron beam and the electromagnetic wave, and worked out the growth rate and start current through numerical calculations. With the help of particle-in-cell simulation, the theoretical predictions are well demonstrated.

  4. Primordial Lepton Oscillations and Baryogenesis

    CERN Document Server

    Hamada, Yuta

    2016-01-01

    The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the $CP$ violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.

  5. Smart contact oscillations by IPMCs

    Science.gov (United States)

    Asanuma, H.; Asaka, K.; Su, J.; Poubel, L.; Shahinpoor, M.

    2016-02-01

    An ion migration-induced self-oscillation phenomenon observed in ionic polymer metal composites (IPMCs) is reported. These oscillations are generated from a purely static equilibrium configuration of IPMCs in loose contact with a stationary electrode, and in particular the anode of an imposed DC voltage source. Many interesting possibilities emerge, which are described in this paper. Of particular importance is the emergence of the possibility of creating tailor-made electric signals or pulse-width modulation-type signals from a DC source.

  6. Primordial lepton oscillations and baryogenesis

    Science.gov (United States)

    Hamada, Yuta; Kitano, Ryuichiro

    2016-11-01

    The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the CP violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.

  7. Anomalous Dissipative Quantum Harmonic Oscillator

    Institute of Scientific and Technical Information of China (English)

    CHEN Dian-Yong; BAI Zhan-Wu; DONG Yu-Bing

    2008-01-01

    We investigate the low-temperature statistical properties of a harmonic oscillator coupled to a heat bath, where the low-frequency spectrum vanishes. We obtain the exact result of the zero point energy. Due to the low frequency shortage of environmental oscillators' spectral density, the coordinate and momentum correlation functions decay as r-4and r-6 respectively at zero temperature, where T is the correlation time. The low-temperature behavior of the mean energy does not violate the third law of thermodynamics, but differs largely from the Ohmic spectrum case.

  8. Resonant solar neutrino oscillation versus laboratory neutrino oscillation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Chong-Sa

    1987-02-01

    The interplay between resonant solar neutrino oscillations and neutrino oscillations in laboratory experiments is investigated in a 3 generation model. Due to the assumed hierarchy of neutrino masses, together with our choice of a convenient parameterization of the 3 generation mixing matrix, we can derive a simple analytic formula which reduces the solar neutrino problem to an effective 2 generation problem. The reduction makes it apparent that the allowed range of mixing and mass parameters crucially depend on whether the survival probability of solar neutrinos S satisfies S greater than or equal to 1/3 or not. The formulae for probabilities of laboratory neutrino oscillations are also greatly simplified. We argue that a combination of the observed solar neutrino depletion and data obtained from reactor experiments seems to rule out some range of neutrino masses. If a sizable nu/sub ..mu../ ..-->.. nu/sub e/ oscillation is observed at accelerators, as suggested at this Workshop, it severely restricts the range of 2 mixing angles.

  9. Potassium Model for Slow (2-3 Hz) In Vivo Neocortical Paroxysmal Oscillations

    Science.gov (United States)

    Bazhenov, M.; Timofeev, I.; Steriade, M.; Sejnowski, T. J.

    2010-01-01

    In slow neocortical paroxysmal oscillations, the de- and hyperpolarizing envelopes in neocortical neurons are large compared with slow sleep oscillations. Increased local synchrony of membrane potential oscillations during seizure is reflected in larger electroencephalographic oscillations and the appearance of spike- or polyspike-wave complex recruitment at 2- to 3-Hz frequencies. The oscillatory mechanisms underlying this paroxysmal activity were investigated in computational models of cortical networks. The extracellular K+ concentration ([K+]o) was continuously computed based on neuronal K+ currents and K+ pumps as well as glial buffering. An increase of [K+]o triggered a transition from normal awake-like oscillations to 2- to 3-Hz seizure-like activity. In this mode, the cells fired periodic bursts and nearby neurons oscillated highly synchronously; in some cells depolarization led to spike inactivation lasting 50–100 ms. A [K+]o increase, sufficient to produce oscillations could result from excessive firing (e.g., induced by external stimulation) or inability of K+ regulatory system (e.g., when glial buffering was blocked). A combination of currents including high-threshold Ca2+, persistent Na+ and hyperpolarization-activated depolarizing (Ih) currents was sufficient to maintain 2- to 3-Hz activity. In a network model that included lateral K+ diffusion between cells, increase of [K+]o in a small region was generally sufficient to maintain paroxysmal oscillations in the whole network. Slow changes of [K+]o modulated the frequency of bursting and, in some case, led to fast oscillations in the 10- to 15-Hz frequency range, similar to the fast runs observed during seizures in vivo. These results suggest that modifications of the intrinsic currents mediated by increase of [K+]o can explain the range of neocortical paroxysmal oscillations in vivo. PMID:15056684

  10. Dynamic analysis of the conditional oscillator underlying slow waves in thalamocortical neurons

    Directory of Open Access Journals (Sweden)

    Francois eDavid

    2016-02-01

    Full Text Available During non-REM sleep the EEG shows characteristics waves that are generated by the dynamic interactions between cortical and thalamic oscillators. In thalamic neurons, low-threshold T-type Ca2+ channels play a pivotal role in almost every type of neuronal oscillations, including slow (<1 Hz waves, sleep spindles and delta waves. The transient opening of T channels gives rise to the low threshold spikes (LTSs, and associated high frequency bursts of action potentials, that are characteristically present during sleep spindles and delta waves, whereas the persistent opening of a small fraction of T channels, (i.e. ITwindow is responsible for the membrane potential bistability underlying sleep slow oscillations. Surprisingly thalamocortical (TC neurons express a very high density of T channels that largely exceed the amount required to generate LTSs and therefore, to support certain, if not all, sleep oscillations. Here, to clarify the relationship between T current density and sleep oscillations, we systematically investigated the impact of the T conductance level on the intrinsic rhythmic activities generated in TC neurons, combining in vitro experiments and TC neuron simulation. Using bifurcation analysis, we provide insights into the dynamical processes taking place at the transition between slow and delta oscillations. Our results show that although stable delta oscillations can be evoked with minimal T conductance, the full range of slow oscillation patterns, including groups of delta oscillations separated by Up states (grouped-delta slow waves requires a high density of T channels. Moreover, high levels of T conductance ensure the robustness of different types of slow oscillations.

  11. Green's Function for the Quartic Oscillator

    OpenAIRE

    Anderson, Robert L.

    2016-01-01

    In this paper, a quantum mechanical Green's function $G_{qo}(y_b,t_b;$ $y_a,t_a)$ for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator $(qo)$ to the harmonic oscillator $(ho)$, second [2], the integration of the classical action function for the quartic oscillator. Here an equivalent form for the quartic oscillator action function $S_{qo}(y_b,t_b;$ $y_a,t_a)$ in terms of harmonic oscillator var...

  12. Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

    Directory of Open Access Journals (Sweden)

    Cheng-Yang Liu

    2009-12-01

    Full Text Available The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa.

  13. Capacitive Micro Pressure Sensor Integrated with a Ring Oscillator Circuit on Chip

    Science.gov (United States)

    Dai, Ching-Liang; Lu, Po-Wei; Chang, Chienliu; Liu, Cheng-Yang

    2009-01-01

    The study investigates a capacitive micro pressure sensor integrated with a ring oscillator circuit on a chip. The integrated capacitive pressure sensor is fabricated using the commercial CMOS (complementary metal oxide semiconductor) process and a post-process. The ring oscillator is employed to convert the capacitance of the pressure sensor into the frequency output. The pressure sensor consists of 16 sensing cells in parallel. Each sensing cell contains a top electrode and a lower electrode, and the top electrode is a sandwich membrane. The pressure sensor needs a post-CMOS process to release the membranes after completion of the CMOS process. The post-process uses etchants to etch the sacrificial layers, and to release the membranes. The advantages of the post-process include easy execution and low cost. Experimental results reveal that the pressure sensor has a high sensitivity of 7 Hz/Pa in the pressure range of 0–300 kPa. PMID:22303167

  14. From biological membranes to biomimetic model membranes

    Directory of Open Access Journals (Sweden)

    Eeman, M.

    2010-01-01

    Full Text Available Biological membranes play an essential role in the cellular protection as well as in the control and the transport of nutrients. Many mechanisms such as molecular recognition, enzymatic catalysis, cellular adhesion and membrane fusion take place into the biological membranes. In 1972, Singer et al. provided a membrane model, called fluid mosaic model, in which each leaflet of the bilayer is formed by a homogeneous environment of lipids in a fluid state including globular assembling of proteins and glycoproteins. Since its conception in 1972, many developments were brought to this model in terms of composition and molecular organization. The main development of the fluid mosaic model was made by Simons et al. (1997 and Brown et al. (1997 who suggested that membrane lipids are organized into lateral microdomains (or lipid rafts with a specific composition and a molecular dynamic that are different to the composition and the dynamic of the surrounding liquid crystalline phase. The discovery of a phase separation in the plane of the membrane has induced an explosion in the research efforts related to the biology of cell membranes but also in the development of new technologies for the study of these biological systems. Due to the high complexity of biological membranes and in order to investigate the biological processes that occur on the membrane surface or within the membrane lipid bilayer, a large number of studies are performed using biomimicking model membranes. This paper aims at revisiting the fundamental properties of biological membranes in terms of membrane composition, membrane dynamic and molecular organization, as well as at describing the most common biomimicking models that are frequently used for investigating biological processes such as membrane fusion, membrane trafficking, pore formation as well as membrane interactions at a molecular level.

  15. B0s Oscillation Results

    CERN Document Server

    Willocq, S

    2002-01-01

    We review new studies of the time dependence of B0s - B0s-bar mixing by the ALEPH, DELPHI and SLD Collaborations, with an emphasis on the different analysis methods used. Combining all available results yields a preliminary lower limit on the oscillation frequency of dms > 14.4 ps-1 at the 95% C.L.

  16. Observation of anharmonic Bloch oscillations.

    Science.gov (United States)

    Dreisow, Felix; Wang, Gang; Heinrich, Matthias; Keil, Robert; Tünnermann, Andreas; Nolte, Stefan; Szameit, Alexander

    2011-10-15

    We report on the experimental observation of Bloch oscillations of an optical wave packet in a lattice with second-order coupling. To this end, we employ zigzag waveguide arrays, in which the second-order coupling can be precisely tuned.

  17. Testing Localization in Neutrino Oscillations

    OpenAIRE

    Zhuridov, Dmitry V.

    2012-01-01

    The neutrino wave packet localization in short-baseline neutrino oscillation experiments, such as MiniBooNE, is investigated. It is shown that the transition from localization to delocalization may be observed for large neutrino mass splitting of order 1 eV, e.g., in theories with sterile neutrinos.

  18. Sound oscillation of dropwise cluster

    Energy Technology Data Exchange (ETDEWEB)

    Shavlov, A.V., E-mail: shavlov@ikz.ru [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation); Dzhumandzhi, V.A.; Romanyuk, S.N. [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation)

    2012-06-04

    There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10{sup 2}–10{sup 3} units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.

  19. Optoelectronic Oscillators for Communication Systems

    Science.gov (United States)

    Romeira, Bruno; Figueiredo, José

    We introduce and report recent developments on a novel five port optoelectronic voltage controlled oscillator consisting of a resonant tunneling diode (RTD) optical-waveguide integrated with a laser diode. The RTD-based optoelectronic oscillator (OEO) has both optical and electrical input and output ports, with the fifth port allowing voltage control. The RTD-OEO locks to reference radio-frequency (RF) sources by either optical or electrical injection locking techniques allowing remote synchronization, eliminating the need of impedance matching between traditional RF oscillators. RTD-OEO functions include generation, amplification and distribution of RF carriers, clock recovery, carrier recovery, modulation and demodulation and frequency synthesis. Self-injection locking operation modes, where small portions of the output electrical/optical signals are fed back into the electrical/optical input ports, are also proposed. The self-phase locked loop configuration can give rise to low-noise high-stable oscillations, not limited by the RF source performance and with no need of external optoelectronic conversion.

  20. Solar Magnetic Waves and Oscillations

    Science.gov (United States)

    Erdelyi von Fay-Siebenburgen, R.

    2006-11-01

    Recent solar and space satellite missions (e.g. SOHO, Trace) and high- resolution ground-based observations (e.g. Swedish Solar Telescope, Dutch Open Telescope) have opened new avenues for 21st century plasma physics. With unprecedented details a very rich and abundant structure of the solar atmosphere is unveiled. Revolutionary observations clearly confirmed the existence of MHD waves and oscillations in a wide range of solar atmospheric magnetic structures, commonly described in the form of solar flux tubes. The objectives of this review are to give an up-to-date account of the theory of MHD waves and oscillations in solar and astrophysical magnetic wave-guides. Since magnetic structuring acts as excellent wave guides, plasma waves and oscillations are able to propagate from sub-surface solar regions through the solar atmosphere deep into the interplanetary space. Observations and theoretical modeling of waves can provide excellent diagnostic tools about the state of solar plasma. Key examples of the various types of MHD waves and oscillations will be discussed both from observational and theoretical perspectives and the concept of atmospheric (coronal) and magneto-seismology will be introduced. The lecture will also contain a few short exercises in order to highlight the important points of the applications of solar MHD wave theory.

  1. Microporous Inorganic Membranes as Proton Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Vichi, F.M. Tejedor-Tejedor, M.I. Anderson, Marc A

    2002-08-28

    Porous oxide electrolyte membranes provide an alternative approach to fabricating proton exchange membrane fuel cells based on inorganic materials. This study focused on elucidating the properties of these inorganic membranes that make them good electrolyte materials in membrane electrode assemblies; in particular, we investigated several properties that affect the nature of proton conductivity in these membranes. This report discusses our findings on the effect of variables such as site density, amount of surface protonation and surface modification on the proton conductivity of membranes with a fixed pore structure under selected conditions. Proton conductivities of these inorganic membranes are similar to conductivities of nafion, the polymeric membrane most commonly used in low temperature fuel cells.

  2. Tunable Oscillations in the Purkinje Neuron

    CERN Document Server

    Abrams, Ze'ev R; Wang, Yuan; Trauner, Dirk; Zhang, Xiang

    2011-01-01

    In this paper, we study the dynamics of slow oscillations in Purkinje neurons in vitro, and derive a strong association with a forced parametric oscillator model. We demonstrate the precise rhythmicity of the oscillations in Purkinje neurons, as well as a dynamic tunability of this oscillation using a photo-switchable compound. We show that this slow oscillation can be induced in every Purkinje neuron, having periods ranging between 10-25 seconds. Starting from a Hodgkin-Huxley model, we also demonstrate that this oscillation can be externally modulated, and that the neurons will return to their intrinsic firing frequency after the forced oscillation is concluded. These results signify an additional functional role of tunable oscillations within the cerebellum, as well as a dynamic control of a time scale in the brain in the range of seconds.

  3. Cyanohydrin reactions enhance glycolytic oscillations in yeast

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav; Nielsen, Astrid Gram; Tortzen, Christian;

    2015-01-01

    Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here...

  4. Opto-Electronic Oscillator and its Applications

    Science.gov (United States)

    Yao, X. S.; Maleki, L.

    1996-01-01

    We present the theoretical and experimental results of a new class of microwave oscillators called opto-electronic oscillators (OEO). We discuss techniques of achieving high stability single mode operation and demonstrate the applications of OEO in photonic communication systems.

  5. Anaerobic membrane bioreactors: Are membranes really necessary?

    NARCIS (Netherlands)

    Davila, M.; Kassab, G.; Klapwijk, A.; Lier, van J.B.

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A

  6. Nonlinear analysis of ring oscillator circuits

    KAUST Repository

    Ge, Xiaoqing

    2010-06-01

    Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.

  7. Optical analogue of electronic Bloch oscillations.

    Science.gov (United States)

    Sapienza, Riccardo; Costantino, Paola; Wiersma, Diederik; Ghulinyan, Mher; Oton, Claudio J; Pavesi, Lorenzo

    2003-12-31

    We report on the observation of Bloch oscillations in light transport through periodic dielectric systems. By introducing a linear refractive index gradient along the propagation direction the optical equivalent of a Wannier-Stark ladder was obtained. Bloch oscillations were observed as time-resolved oscillations in transmission, in direct analogy to electronic Bloch oscillations in conducting crystals where the Wannier-Stark ladder is obtained via an external electric field. The observed oscillatory behavior is in excellent agreement with transfer matrix calculations.

  8. Internal dynamics of long Josephson junction oscillators

    DEFF Research Database (Denmark)

    Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.;

    1981-01-01

    Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numeric...... results imply a ''bunched-fluxon'' mode of oscillation at larger values of bias current. Applied Physics Letters is copyrighted by The American Institute of Physics....

  9. Parametric resonance in neutrino oscillations in matter

    Indian Academy of Sciences (India)

    E Kh Akhmedov

    2000-01-01

    Neutrino oscillations in matter can exhibit a specific resonance enhancement - parametric resonance, which is different from the MSW resonance. Oscillations of atmospheric and solar neutrinos inside the earth can undergo parametric enhancement when neutrino trajectories cross the core of the earth. In this paper we review the parametric resonance of neutrino oscillations in matter. In particular, physical interpretation of the effect and the prospects of its experimental observation in oscillations of solar and atmospheric neutrinos in the earth are discussed.

  10. Circadian- and Light-Dependent Regulation of Resting Membrane Potential and Spontaneous Action Potential Firing of Drosophila Circadian Pacemaker Neurons

    OpenAIRE

    Sheeba, Vasu; Gu, Huaiyu; Sharma, Vijay K.; O'Dowd, Diane K.; Holmes, Todd C

    2007-01-01

    The ventral lateral neurons (LNvs) of adult Drosophila brain express oscillating clock proteins and regulate circadian behavior. Whole cell current-clamp recordings of large LNvs in freshly dissected Drosophila whole brain preparations reveal two spontaneous activity patterns that correlate with two underlying patterns of oscillating membrane potential: tonic and burst firing of sodium-dependent action potentials. Resting membrane potential and spontaneous action potential firing are rapidly ...

  11. Bloch-Zener oscillations in binary superlattices.

    Science.gov (United States)

    Dreisow, F; Szameit, A; Heinrich, M; Pertsch, T; Nolte, S; Tünnermann, A; Longhi, S

    2009-02-20

    Bloch-Zener oscillations, i.e., the coherent superposition of Bloch oscillations and Zener tunneling between minibands of a binary lattice, are experimentally demonstrated for light waves in curved femtosecond laser-written waveguide arrays. Visualization of double-periodicity breathing and oscillation modes is reported, and synchronous tunneling leading to wave reconstruction is demonstrated.

  12. On the excitation of Goodwin's oscillations

    Science.gov (United States)

    Antonova, A. O.; Reznik, S. N.; Todorov, M. D.

    2014-11-01

    We consider the necessary condition for excitation of long-periodic Goodwin's oscillations and short-periodic sawtooth oscillations in the Goodwin model with fixed delay in the induced investment. Also, using the method of equivalent linearization we evaluate the amplitude of steady-state oscillation.

  13. Control linearity and jitter of relaxation oscillators

    NARCIS (Netherlands)

    Gierkink, Sander Laurentius Johannes

    1999-01-01

    The body of this thesis (chapters 3,4 and 5) deals with the analysis and improvement of a specific class of voltage- or current controlled oscillators (VCO’s respectively CCO’s) called relaxation oscillators. Before going into detail on this particular class of oscillators, first the function and ap

  14. The SD oscillator and its attractors

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Q [Department of Mathematics and Physics, Shijiazhuang Railway Institute, Shijiazhuang 050043 (China); Wiercigroch, M; Pavlovskaia, E; Grebogi, C; Michael, J; Thompson, T [Centre for Applied Dynamics Research, School of Engineering, University of Aberdeen, King' s College, Aberdeen AB24 3UE, Scotland (United Kingdom)], E-mail: qingjiecao@hotmail.com

    2008-02-15

    We propose a new archetypal oscillator for smooth and discontinuous systems (SD oscillator). This oscillator behaves both smooth and discontinuous system depending on the value of the smoothness parameter. New dynamic behaviour is presented for the transitions from the smooth to discontinuous regime.

  15. 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 e...

  16. Erythrocyte membrane proteins and membrane skeleton

    Institute of Scientific and Technical Information of China (English)

    LU Yiqin; LIU Junfan

    2007-01-01

    Considerable advances in the research field of erythrocyte membrane were achieved in the recent two decades.New findings in the structure-function correlation and interactions of erythrocyte membrane proteins have attracted extensive attention.Interesting progress was also made in the molecular pathogenesis of erythrocyte membrane disorders.Advances in the composition,function and interaction of erythrocyte membrane proteins,erythrocyte membrane skeleton,and relevant diseases are briefly described and summarized here on the basis of domestic and world literatures.

  17. The effect of phase stabilization of microwave oscillations in nanosecond Gunn oscillators

    Science.gov (United States)

    Konev, V. Yu.; Klimov, A. I.; Koval'chuk, O. B.; Gubanov, V. P.; Kozhevnikov, V. Yu.; Kozyrev, A. V.; Torkhov, N. A.

    2013-11-01

    The effect of the semiconductor structure of an oscillator diode on the phase stabilization of microwave oscillations in a nanosecond Gunn oscillator by using a modulating voltage pulse edge is investigated. Numerical simulation is employed to determine phase deviations depending on the scatter of pulseedge duration and pulse amplitude. The standard deviation of phase-delay time of microwave oscillations in the oscillator with regard to a constant level at the modulating pulse edge and the standard deviation of phase difference of microwave oscillations in two electrodynamically insulated oscillators connected in parallel to one and the same modulator have been measured.

  18. 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.

  19. 球囊扩张Apollo支架植入术治疗症状性基底动脉狭窄%Treatment of symptomatic basilar artery stenosis with balloon expandable Apollo stent

    Institute of Scientific and Technical Information of China (English)

    张帆; 蔡玉琴; 郭贵军; 郜利会; 吕彦锋; 徐国栋; 孟庆溪

    2012-01-01

    Objective To observe the safety and effectiveness of balloon expandable Apollo stent for the treatment of symptomatic basilar artery stenosis. Methods Eighteen patients with symptomatic basilar artery stenosis (all >70%) were treated with Apollo stent The mean time of clinical follow-up was 11 months. Clinical evaluation was performed based on the modified Rankin Scale (mRS). Results The stent placement was technically successful in all 18 patients. Clinical symptoms were improved in 16 patients after stenting. The mRS scores of 14 patients after stenting were ≤2, while of 4 patients were >2. Conclusion Balloon expandable Apollo stem placement is a safe and efficacious alternative for the treatment of symptomatic basilar stenosis.%目的 观察球囊扩张支架植入术治疗症状性基底动脉狭窄的疗效及安全性.方法 应用Apollo支架治疗18例症状性基底动脉严重狭窄(>70%)患者,术后平均随访11个月,以改良Rankin量表(mRS)评分为基础评价治疗效果.结果 对所有患者均成功植入支架,16例患者临床症状得到不同程度改善;18例中,14例mRS评分≤2分,4例mRS评分>2分.结论 球囊扩张支架植入术治疗症状性基底动脉狭窄安全、有效.

  20. 都梁软胶囊治疗基底动脉型偏头痛39例%Clinical Therapy Observation of Duliang Soft Capsule for Treating Basilar Artery Migraine in 39 Cases

    Institute of Scientific and Technical Information of China (English)

    陈忠伦; 王欣; 段劲峰

    2012-01-01

    目的 观察都梁软胶囊时基底动脉型偏头痛的治疗效果.方法 将76例患者随机分成治疗组(39例)和对照组(37例),治疗组联合服用都梁软胶囊和尼莫地平,对照组单用尼莫地平,治疗2周,观察疼痛及伴随症状的变化.结果 治疗组比对照组疼痛强度降低更明显(P<0.05),总有效率亦高于对照组(P<0.05).结论联合服用都梁软胶囊治疗基底动脉型偏头痛安全、有效.%Objective To investigate the effect of Duliang Soft Capsule in treating basilar artery migraine. Methods 76 cases of basilar artery migraine were randomly divided into two groups, the treatment group( 39 cases) and the control group( 37 cases ). The treatment group was given Duliang Soft Capsule plus nimodipine, while the control group received nimodipine alone. The change of pain and accompanied symptoms were observed after 2 - week treatment. Results The pain intensity in the treatment group was significantly decreased than the control group( P < 0. 05 ), the total effective rate was also higher than that in the control group( P < 0.05). Conclusion The combination use of Duliang Soft Capsule is safe and effective to treat basilar artery migraine.

  1. 基底动脉狭窄与认知功能改变的临床分析%Relation between basilar artery stenosis and cognitive impairment

    Institute of Scientific and Technical Information of China (English)

    李慧英; 黄一宁; 叶长青; 白静

    2012-01-01

    Objective To study the relation between autoregulation of bilateral posterior cerebral artery flow and cognitive function in patients with basilar artery stenosis. Methods Fifteen patients with basilar artery stenosis were divided into stenosis group without cerebral infaction(n = 9) and stenosis group with cerebral infaction(n = 6). Ten healthy volunteers served as a control group. Autoregulation of bilateral posterior cerebral artery flow was assessed by transcranial Doppler ultrasound breath holding test and oblique test. Executive function,structural skill,auditory, visual and logical memory, information processing speed and visuospatial ability were assayed according to the overall neurophysiolgy test and Montreal cognitive assessment(MCA). Results The information processing speed and visuospatial ability were significantly lower in stenosis group with cerebral infarction than in control group(P<0. 05). The visuospatial ability was significantly higher in stenosis group with cerebral infarction than in stenosis group without cerebral infarction(P<0. 05). The breath holding index of posterior cerebral artery and the proportion of anterior and posterior circulating vascular motion reactivity were significantly lower in stenosis group with cerebral infarction and stenosis group without cerebral infarction than in control group (P<0. 05). The proportion of anterior and posterior circulating vascular motion reactivity was positively related with the visuospatial ability (r=0. 830, P<0. 05). Conclusion Patients with basilar artery stenosis may have cognitive impairment at different severity before cerebral infarction and its hemodynamic change is related with cognitive impairment.%目的 探讨基底动脉狭窄患者双侧大脑后动脉的脑血流自动调节变化与认知功能改变之间的关系.方法 选择基底动脉狭窄患者15例,并根据有无脑梗死分为狭窄无梗死组9例和狭窄梗死组6例,另选健康体检者10例为对照组.应用

  2. Classification and its clinical significance of basilar invagination%颅底凹陷症的分型及其意义

    Institute of Scientific and Technical Information of China (English)

    王建华; 尹庆水; 夏虹; 艾福志; 吴增晖; 马向阳; 章凯

    2011-01-01

    Objective:To investigate the classification of basilar invaglnation so as to provide a criterion for surgery determination. Method:70 cases suffering basilar invagination determined by radiography,CT and MRI from March 2007 to March 2010 in our hospital were divided into two groups (stable group and unstable group) based on present of atlas-occipital or atlas-axis dislocation.The deformities such as occipital-atlas fusion,Chiari malformation,slippage of the axis facets,syringomyelia were recorded.Several parameters including clivus slope,distance from odontoid to Chamberlain line and distance form odontoid to foramen magnum line were measured,and the spine medulla compression and the sursical approach of each group were recorded respectively. Result:20 cases were termed as stable and 50 as unstable. Among the stable group,there were 18 Chiari deformity(90%) and 15 syringomyelia(75%);while among the unstable group,there were 2 Chiari deformity (4%),46 occipital-atalas fusion(92%),37 slippage of upper facets(74%),and 43 syringomyelia( 86% ).And the clivns slope angle was 168°±5° and 133°±11° for stable and unstable group respectively(P<0.05);the distance from odontoid to the Chamberlain line was -4,8±4.2mm and -5.6±3.7mm for stable and unstable group respectively (P>0.05);and the distance form odontoid to the foramen magnum line was 0.5±-0.3mm and -6.9±2.9mm for stable and unstable group respectively (P<0.05).In the stable group,2 cases complicated with ventral medulla compression, 11 with dorsal and 7 cases with both underwent the posterior cranial fossa decompression;while all 50 unstable cases(44 with ventral and 6 with both ventral and dorsal medulla compressions) experienced transoral anterior release and instrumentation. Conclusion:The basilar invagination can be divided into two types based on present of atlas-occipital or atls-axls dislocation,which is used to differentiate the anatomic and clinical characters for both groups and

  3. Measuring neutrino oscillation parameters using $\

    Energy Technology Data Exchange (ETDEWEB)

    Backhouse, Christopher James [Oriel College, Oxford (United Kingdom)

    2011-01-01

    MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δmatm2 and sin2atm). The oscillation signal consists of an energy-dependent deficit of vμ interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the vμ-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the vμ-disappearance analysis, incorporating this new estimator were: Δm2 = 2.32-0.08+0.12 x 10-3 eV2, sin 2 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$μ beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36-0.40+0.46(stat.) ± 0.06(syst.)) x 10-3eV2, sin2 2$\\bar{θ}$ = 0.86-0.12_0

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

    Science.gov (United States)

    Majhi, Soumen; Bera, Bidesh K.; Bhowmick, Sourav K.; Ghosh, Dibakar

    2016-10-01

    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.

  5. Deformation of a soft interface by an oscillating microbubble

    Science.gov (United States)

    Tinguely, Marc; Matar, Omar; Garbin, Valeria

    2014-11-01

    Acoustically driven oscillating bubbles are used in biomedical applications, for instance to promote pore formation in cell membranes and enhance gene transfection, or to transiently open the blood-brain barrier, which is otherwise impermeable to drugs. However, control over the stresses generated by oscillating bubbles on cells and tissues is still lacking. We use high-speed video microscopy to observe the deformation of a soft interface (agarose gel, a hydrogel that is commonly used as tissue phantom) by the oscillations of a bubble. The mechanical properties of the hydrogel can be tuned to mimic different tissues. The deformation is measured by tracking the displacement of tracer particles embedded in the gel. The results show that the deformation is due to the ``push and pull'' motion of the bubble against the soft surface. The phase of the deformation varies with the distance to the bubble, which can be explained by the viscoelastic properties of the gel. National Swiss Foundation, and EPSRC Programme Grant EP/K003976/1.

  6. Impressão basilar e malformação de Arnold-Chiari: considerações técnico-cirúrgicas a propósito de 13 casos

    Directory of Open Access Journals (Sweden)

    José A. Gonçalves da Silva

    1978-03-01

    Full Text Available Os autores empregaram detalhes técnicos pessoais para descompressão da fossa posterior em casos de impressão basilar e/ou maliormação de Arnold-Chiari, consistente em intuoação endotraqueal sem retroflexão da cabeça do paciente, sendo o mesmo operado em posição sentada e com a cabeça ereta. Foi realizada plástica da paquimeninge da fossa posterior com dura-mater de cadáver conservada em glicerina.

  7. The experience for stent assisted therapy application on complicated basilar artery apex aneurysm%支架辅助技术介入治疗复杂基底动脉顶端动脉瘤的临床应用

    Institute of Scientific and Technical Information of China (English)

    张金峰; 张向艳; 左书浩; 王东; 李建华; 屈浙; 田军; 胡昱红

    2015-01-01

    目的:总结采用支架辅助技术结合弹簧圈介入治疗复杂基底动脉顶端动脉瘤中的经验,并评估其安全性。方法回顾分析27例复杂基底动脉顶端动脉瘤,采用支架技术结合弹簧圈栓塞基底动脉顶端动脉瘤的临床资料。结果27例手术完成,影像学示完全填塞19例,近全填塞7例,疏松填塞1例。手术并发症3例:1例出血,1例载瘤动脉闭塞,1例弹簧圈脱落。死亡2例:1例V级,1例术前2次出血。结论支架辅助技术结合弹簧圈介入治疗复杂基底动脉顶端动脉瘤是一种可选择的、安全的、有效的方法。%Objective To evaluate the security of application with stent assisted therapy combined with axiom detach-able coil on complicated basilar artery apex aneurysm. Method To review and analyze 27 complicated basilar artery apex aneurysm surgery cases, using the application of stent assisted therapy combined with detachable coil deal with the basilar artery apex aneurysm. Result The image of the 27 surgery cases showed that 19 cases were completed tamponed, and 7 cased were nearly completed tamponed, 1 loose tamponed. It also had three operation complica-tions:one hemorrhaged, one parent artery occlusion, one coil detached. 2 death cases: one was V-level, another had secondary hemorrhaged before surgery. Conclusion The application with stent assisted therapy on complicated basilar artery apex aneurysm is selectable, safe and effective.

  8. Photonic cavity synchronization of nanomechanical oscillators.

    Science.gov (United States)

    Bagheri, Mahmood; Poot, Menno; Fan, Linran; Marquardt, Florian; Tang, Hong X

    2013-11-22

    Synchronization in oscillatory systems is a frequent natural phenomenon and is becoming an important concept in modern physics. Nanomechanical resonators are ideal systems for studying synchronization due to their controllable oscillation properties and engineerable nonlinearities. Here we demonstrate synchronization of two nanomechanical oscillators via a photonic resonator, enabling optomechanical synchronization between mechanically isolated nanomechanical resonators. Optical backaction gives rise to both reactive and dissipative coupling of the mechanical resonators, leading to coherent oscillation and mutual locking of resonators with dynamics beyond the widely accepted phase oscillator (Kuramoto) model. In addition to the phase difference between the oscillators, also their amplitudes are coupled, resulting in the emergence of sidebands around the synchronized carrier signal.

  9. 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.

  10. Electrochemical Oscillations Induced by Surfactants

    Institute of Scientific and Technical Information of China (English)

    翟俊红; 贺占博

    2003-01-01

    A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.

  11. Neutrino Oscillations in Dense Matter

    Science.gov (United States)

    Lobanov, A. E.

    2017-03-01

    A modification of the electroweak theory, where the fermions with the same electroweak quantum numbers are combined in multiplets and are treated as different quantum states of a single particle, is proposed. In this model, mixing and oscillations of particles arise as a direct consequence of the general principles of quantum field theory. The developed approach enables one to calculate the probabilities of the processes taking place in the detector at long distances from the particle source. Calculations of higher-order processes, including computation of the contributions due to radiative corrections, can be performed in the framework of the perturbation theory using the regular diagram technique. As a result, the analog to the Dirac-Schwinger equation of quantum electrodynamics describing neutrino oscillations and its spin rotation in dense matter can be obtained.

  12. Experimental studies of neutrino oscillations

    CERN Document Server

    Kajita, Takaaki

    2016-01-01

    The 2015 Nobel Prize in physics has been awarded to Takaaki Kajita and Arthur McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita of Tokyo University is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into as well as a record of the rise and the role of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the 3 families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible foot-print in the history of big and better science.

  13. Oscillators: Old and new perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Jayanta K. [Harish-Chandra Research Institute, Jhunsi, Allahabad 211019 (India); Roy, Jyotirmoy [UM-DAE Centre for Excellence in Basic Sciences, Santa Cruz(E), Mumbai 400098 (India)

    2014-02-11

    We consider some of the well known oscillators in literature which are known to exhibit interesting effects of nonlinearity. We review the Lindstedt-Poincare technique for dealing with with the nonlinear effects and then go on to introduce the relevance of the renormalization group for the oscillator following the pioneering work of Chen et al. It is pointed out that the traditional Lindstedt-Poincare and the renormalization group techniques have operational connections. We use this to find an unexpected mode softening in the double pendulum. This mode softening prompted us to look for chaos in the double pendulum at low energies-energies that are just sufficient to allow the outer pendulum to rotate (the double pendulum is known to be chaotic at high energies-energies that are greater than that needed to make both pendulums to rotate). The emergence of the chaos is strongly dependent on initial conditions.

  14. A Tunable Carbon Nanotube Oscillator

    Science.gov (United States)

    Sazonova, Vera

    2005-03-01

    Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.

  15. Cubication of conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Belendez, Augusto; Alvarez, Mariela L [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, Elena; Pascual, Inmaculada [Departamento de Optica, FarmacologIa y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es

    2009-09-15

    A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.

  16. Status of sterile neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Schwetz, Thomas

    2013-02-15

    There are several independent hints for neutrino oscillations with a mass-squared difference at the eV{sup 2} scale. If confirmed, this would imply the existence of sterile neutrinos. I discuss the present status of the hints for ν{sub e} disappearance from reactor experiments and Gallium source experiments, as well as from the LSND and MiniBooNE ν{sub μ}→ν{sub e} appearance searches. A consistent interpretation of the global data in terms of neutrino oscillations is challenged by the non-observation of a positive signal in ν{sub μ} disappearance experiments. There is a strong tension in the global data, irrespective of the number of eV-scale neutrino states.

  17. Mathematical Models of Biochemical Oscillations

    OpenAIRE

    Conrad, Emery David

    1999-01-01

    The goal of this paper is to explain the mathematics involved in modeling biochemical oscillations. We first discuss several important biochemical concepts fundamental to the construction of descriptive mathematical models. We review the basic theory of differential equations and stability analysis as it relates to two-variable models exhibiting oscillatory behavior. The importance of the Hopf Bifurcation will be discussed in detail for the central role it plays in limit cycle behavior and...

  18. Ermakov approach for minisuperspace oscillators

    OpenAIRE

    Rosu, H. C.; Socorro, J.

    1999-01-01

    The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a p...

  19. Multipartite entanglement in neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)

    2009-06-01

    Particle mixing is related to multi-mode entanglement of single-particle states The occupation number of both flavor eigenstates and mass eigenstates can be used to define a multiqubit space. In such a framework, flavor neutrino states can be interpreted as multipartite mode-entangled states. By using two different entanglement measures, we analyze the behavior of multipartite entanglement in the phenomenon of neutrino oscillations.

  20. Neutrino Masses and Flavor Oscillations

    Science.gov (United States)

    Wang, Yifang; Xing, Zhi-Zhong

    2016-10-01

    This essay is intended to provide a brief description of the peculiar properties of neutrinos within and beyond the standard theory of weak interactions. The focus is on the flavor oscillations of massive neutrinos, from which one has achieved some striking knowledge about their mass spectrum and flavor mixing pattern. The experimental prospects towards probing the absolute neutrino mass scale, possible Majorana nature and CP-violating effects, will also be addressed.

  1. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

    This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.

  2. Composite sensor membrane

    Science.gov (United States)

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

    A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

  3. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jurgen

    2013-10-31

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  4. Micro-machined resonator oscillator

    Science.gov (United States)

    Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.

    1994-01-01

    A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.

  5. Automatic oscillator frequency control system

    Science.gov (United States)

    Smith, S. F. (Inventor)

    1985-01-01

    A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.

  6. Neutrino Oscillation Experiment at JHF

    CERN Multimedia

    2002-01-01

    T2K is a long baseline neutrino experiment designed to investigate how neutrinos change from one flavor to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K, 295 km away: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos. The high intensity neutrino beam is produced in an off-axis configuration. The peak neutrino energy is tuned to the oscillation maximum of ∼ 0.6 GeV to maximize the sensitivity to neutrino oscillations. The science goals of T2K can be summarized as follows: •\tsearch for CP violation in the neutrino sector •\tdiscovery of νμ → νe ( i.e. the confirmation that θ13 > 0 ) •\tprecision ...

  7. Quantum dynamics of the damped harmonic oscillator

    CERN Document Server

    Philbin, T G

    2012-01-01

    The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot directly yield dynamics such as Ohmic damping (proportional to velocity) of the oscillator of interest. By using a continuum of oscillators as a reservoir, we canonically quantize the harmonic oscillator with Ohmic damping and also with general damping behaviour. The dynamics of a damped oscillator is determined by an arbitrary effective susceptibility that obeys Kramers-Kronig relations. This approach offers an alternative description of nano-mechanical oscillators and opto-mechanical systems.

  8. Dysrhythmias of the respiratory oscillator

    Science.gov (United States)

    Paydarfar, David; Buerkel, Daniel M.

    1995-03-01

    Breathing is regulated by a central neural oscillator that produces rhythmic output to the respiratory muscles. Pathological disturbances in rhythm (dysrhythmias) are observed in the breathing pattern of children and adults with neurological and cardiopulmonary diseases. The mechanisms responsible for genesis of respiratory dysrhythmias are poorly understood. The present studies take a novel approach to this problem. The basic postulate is that the rhythm of the respiratory oscillator can be altered by a variety of stimuli. When the oscillator recovers its rhythm after such perturbations, its phase may be reset relative to the original rhythm. The amount of phase resetting is dependent upon stimulus parameters and the level of respiratory drive. The long-range hypothesis is that respiratory dysrhythmias can be induced by stimuli that impinge upon or arise within the respiratory oscillator with certain combinations of strength and timing relative to the respiratory cycle. Animal studies were performed in anesthetized or decerebrate preparations. Neural respiratory rhythmicity is represented by phrenic nerve activity, allowing use of open-loop experimental conditions which avoid negative chemical feedback associated with changes in ventilation. In animal experiments, respiratory dysrhythmias can be induced by stimuli having specific combinations of strength and timing. Newborn animals readily exhibit spontaneous dysrhythmias which become more prominent at lower respiratory drives. In human subjects, swallowing was studied as a physiological perturbation of respiratory rhythm, causing a pattern of phase resetting that is characterized topologically as type 0. Computational studies of the Bonhoeffer-van der Pol (BvP) equations, whose qualitative behavior is representative of many excitable systems, supports a unified interpretation of these experimental findings. Rhythmicity is observed when the BvP model exhibits recurrent periods of excitation alternating with

  9. Temperature- and concentration-dependence of kainate-induced y oscillation in rat hippocampal slices under submerged condition

    Institute of Scientific and Technical Information of China (English)

    Cheng-biao LU; Zhi-hua WANG; Yan-hong ZHOU; Martin VREUGDENHIL

    2012-01-01

    Aim:Fast neuronal network oscillation at the y frequency band (y oscillation:30-80 Hz) has been studied extensively in hippocampal slices under interface recording condition.The aim of this study is to establish a method for recording Y oscillation in submerged hippocampal slices that allows simultaneously monitoring Y oscillation and the oscillation-related intracellular events,such as intracellular Ca2+ concentration or mitochondrial membrane potentials.Methods:Horizontal hippocampal slices (thickness:300 pm) of adult rats were prepared and placed in a submerged or an interface chamber.Extracellular field recordings Were made in the CA3c pyramidal layer of the slices.Kainate,an AMPA/kainate receptor agonist,was applied via perfusion.Data analysis was performed off-line.Results:Addition of kainate (25-1000 nmol/L) induced Y oscillation in both the submerged and interface slices.Kainate increased the Y power in a concentration-dependent manner,but the duration of steady state oscillation was reduced at higher concentrations of kainate.Long-lasting Y oscillation was maintained at the concentrations of 100-300 nmol/L.Under submerged condition,Y oscillation was temperature-dependent,with the maximum power achieved at 29℃.The induction of Y oscillation under submerged condition also required a fast rate of perfusion (5-7 mL/min) and showed a fast dynamic during development and after the washout.Conclusion:The kainite-induced Y oscillation recorded in submerged rat hippocampal slices is useful for studying the intracellular events related to neuronal network activities and may represent a model to reveal the mechanisms underlying the normal neuronal synchronizations and diseased conditions.

  10. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  11. 补阳还五汤治疗椎基底动脉供血不足所致眩晕34例%Treating 34 cases of vertigo caused by vertebro-basilar artery insufficiency with the Buyanghuanwu decoction

    Institute of Scientific and Technical Information of China (English)

    万继松; 田中旺

    2012-01-01

      Objective: To observe the clinical effect of the Buyang Huanwu decoction in treating vertigo caused by vertebro-basilar artery insufficiency. Methods: The Buyang Huanwu decoction was given once a day modified with different symptoms. There were 20 days in each course of treatment. The clinical effect was observed after 2 courses of treatment. Results: The total effective rate was 91%. Conclusion: The Buyang Huanwu decoction had significant effect in treating vertigo caused by vertebro-basilar artery insufficiency.%  目的:观察补阳还五汤治疗椎基底动脉供血不足所致眩晕的临床疗效。方法:给予补阳还五汤,并随证加味治疗,1剂/d,20d 为1个疗程,2个疗程后观察疗效。结果:总有效率91%。结论:补阳还五汤治疗基底动脉供血不足所致眩晕疗效显著。

  12. Quantizing the damped harmonic oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Latimer, D C [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)

    2005-03-04

    We consider the Fermi quantization of the classical damped harmonic oscillator (dho). In past work on the subject, authors double the phase space of the dho in order to close the system at each moment in time. For an infinite-dimensional phase space, this method requires one to construct a representation of the CAR algebra for each time. We show that the unitary dilation of the contraction semigroup governing the dynamics of the system is a logical extension of the doubling procedure, and it allows one to avoid the mathematical difficulties encountered with the previous method.

  13. Ermakov approach for minisuperspace oscillators

    CERN Document Server

    Rosu, H C

    1999-01-01

    The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a possible means of describing cosmological evolution. Finally, we comment on the analogy with the accelerator physics

  14. Bloch oscillations in atom interferometry

    CERN Document Server

    Cladé, Pierre

    2014-01-01

    In Paris, we are using an atom interferometer to precisely measure the recoil velocity of an atom that absorbs a photon. In order to reach a high sensitivity, many recoils are transferred to atoms using the Bloch oscillations technique. In this lecture, I will present in details this technique and its application to high precision measurement. I will especially describe in details how this method allows us to perform an atom recoil measurement at the level of $1.3 \\times 10^{-9}$. This measurement is used in the most precise determination of the fine structure constant that is independent of quantum electrodynamics.

  15. Magnus approximation in neutrino oscillations

    Science.gov (United States)

    Acero, Mario A.; Aguilar-Arevalo, Alexis A.; D'Olivo, J. C.

    2011-04-01

    Oscillations between active and sterile neutrinos remain as an open possibility to explain some anomalous experimental observations. In a four-neutrino (three active plus one sterile) mixing scheme, we use the Magnus expansion of the evolution operator to study the evolution of neutrino flavor amplitudes within the Earth. We apply this formalism to calculate the transition probabilities from active to sterile neutrinos with energies of the order of a few GeV, taking into account the matter effect for a varying terrestrial density.

  16. Neutrino Oscillation Studies with Reactors

    CERN Document Server

    Vogel, Petr; Zhang, Chao

    2015-01-01

    Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.

  17. Carnot cycle for an oscillator

    Science.gov (United States)

    Arnaud, Jacques; Chusseau, Laurent; Philippe, Fabrice

    2002-09-01

    In 1824 Carnot established that the efficiency of cyclic engines operating between a hot bath at absolute temperature Thot and a bath at a lower temperature Tcold cannot exceed 1 - Tcold/Thot. We show that linear oscillators alternately in contact with hot and cold baths obey this principle in the quantum as well as classical regime. The expression of the work performed is derived from a simple prescription. Reversible and non-reversible cycles are illustrated. The paper begins with historical considerations and is essentially self-contained.

  18. Strange nonchaotic self-oscillator

    Science.gov (United States)

    Jalnine, Alexey Yu.; Kuznetsov, Sergey P.

    2016-08-01

    An example of strange nonchaotic attractor (SNA) is discussed in a dissipative system of mechanical nature driven by a constant torque applied to one of the elements of the construction. So the external force is not oscillatory, and the system is autonomous. Components of the motion with incommensurable frequencies emerge due to the irrational ratio of the sizes of the involved rotating elements. We regard the phenomenon as strange nonchaotic self-oscillations, and its existence sheds new light on the question of feasibility of SNA in autonomous systems.

  19. Wave Physics Oscillations - Solitons - Chaos

    CERN Document Server

    Nettel, Stephen

    2009-01-01

    This textbook is intended for those second year undergraduates in science and engineering who will later need an understanding of electromagnetic theory and quantum mechanics. The classical physics of oscillations and waves is developed at a more advanced level than has been customary for the second year, providing a basis for the quantum mechanics that follows. In this new edition the Green's function is explained, reinforcing the integration of quantum mechanics with classical physics. The text may also form the basis of an "introduction to theoretical physics" for physics majors. The concluding chapters give special attention to topics in current wave physics: nonlinear waves, solitons, and chaotic behavior.

  20. Modeling of Coupled Chaotic Oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Y. [Departments of Physics and Astronomy and of Mathematics, University of Kansas, Lawrence, Kansas 66045 (United States); Grebogi, C. [Institute for Plasma Research, Department of Mathematics, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)

    1999-06-01

    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} {ital 1999} {ital The American Physical Society}

  1. Visual Grouping by Neural Oscillators

    CERN Document Server

    Yu, Guoshen

    2008-01-01

    Distributed synchronization is known to occur at several scales in the brain, and has been suggested as playing a key functional role in perceptual grouping. State-of-the-art visual grouping algorithms, however, seem to give comparatively little attention to neural synchronization analogies. Based on the framework of concurrent synchronization of dynamic systems, simple networks of neural oscillators coupled with diffusive connections are proposed to solve visual grouping problems. Multi-layer algorithms and feedback mechanisms are also studied. The same algorithm is shown to achieve promising results on several classical visual grouping problems, including point clustering, contour integration and image segmentation.

  2. Making space for harmonic oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Michelotti, Leo; /Fermilab

    2004-11-01

    If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.

  3. Bruno Pontecorvo and Neutrino Oscillations

    Directory of Open Access Journals (Sweden)

    Samoil M. Bilenky

    2013-01-01

    Full Text Available I discuss briefly in this review, dedicated to the centenary of the birth of the great neutrino physicist Bruno Pontecorvo, the following ideas he proposed: (i the radiochemical method of neutrino detection; (ii the μ - e universality of the weak interaction; (iii the accelerator neutrino experiment which allowed to prove that muon and electron neutrinos are different particles (the Brookhaven experiment. I consider in some details Pontecorvo's pioneering idea of neutrino masses, mixing, and oscillations and the development of this idea by Pontecorvo, by Pontecorvo and Gribov, and by Pontecorvo and myself.

  4. Pair creation and plasma oscillations.

    Energy Technology Data Exchange (ETDEWEB)

    Prozorkevich, A. V.; Vinnik, D. V.; Schmidt, S. M.; Hecht, M. B.; Roberts, C. D.

    2000-12-15

    We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background fields and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses.

  5. Membrane Automata with Priorities

    Institute of Scientific and Technical Information of China (English)

    Luděk Cienciala; Lucie Ciencialová

    2004-01-01

    In this paper the one-way P automata with priorities are introduced. Such automata are P systemshere the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane intc the system. The rules associated in some order with each membrane cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

  6. Entangled states of spin and clock oscillators

    Science.gov (United States)

    Polzik, Eugene

    2016-05-01

    Measurements of one quadrature of an oscillator with precision beyond its vacuum state uncertainty have occupied a central place in quantum physics for decades. We have recently reported the first experimental implementation of such measurement with a magnetic oscillator. However, a much more intriguing goal is to trace an oscillator trajectory with the precision beyond the vacuum state uncertainty in both position and momentum, a feat naively assumed not possible due to the Heisenberg uncertainty principle. We have demonstrated that such measurement is possible if the oscillator is entangled with a quantum reference oscillator with an effective negative mass. The key element is the cancellation of the back action of the measurement on the composite system of two oscillators. Applications include measurements of e.-m. fields, accelleration, force and time with practically unlimited accuracy. In a more general sense, this approach leads to trajectories without quantum uncertainties and to achieving new fundamental bounds on the measurement precision.

  7. Damped transverse oscillations of interacting coronal loops

    CERN Document Server

    Soler, Roberto

    2015-01-01

    Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical conditions of the coronal medium. Some observations suggest that interaction between neighboring oscillating loops in an active region may be important and can modify the properties of the oscillations compared to those of an isolated loop. Here we theoretically investigate resonantly damped transverse oscillations of interacting non-uniform coronal loops. We provide a semi-analytic method, based on the T-matrix theory of scattering, to compute the frequencies and damping rates of collective oscillations of an arbitrary configuration of parallel cylindrical loops. The effect of resonant damping is included in the T-matrix scheme in the thin boundary approximation. ...

  8. Phase noise and frequency stability in oscillators

    CERN Document Server

    Rubiola, Enrico

    2009-01-01

    Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...

  9. Collective neutrino oscillations and spontaneous symmetry breaking

    Science.gov (United States)

    Duan, Huaiyu

    2015-08-01

    Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillations.

  10. Lepton asymmetry and neutrino oscillations interplay

    Energy Technology Data Exchange (ETDEWEB)

    Kirilova, Daniela, E-mail: dani@astro.bas.bg [Bulgarian Academy of Sciences, Institute of Astronomy and NAO (Bulgaria)

    2013-03-15

    We discuss the interplay between lepton asymmetry L and {nu} oscillations in the early Universe. Neutrino oscillations may suppress or enhance previously existing L. On the other hand L is capable to suppress or enhance neutrino oscillations. The mechanism of L enhancement in MSW resonant {nu} oscillations in the early Universe is numerically analyzed. L cosmological effects through {nu} oscillations are discussed. We discuss how L may change the cosmological BBN constraints on neutrino and show that BBN model with {nu}{sub e}{r_reversible}{nu}{sub s} oscillations is extremely sensitive to L - it allows to obtain the most stringent constraints on L value. We discuss also the cosmological role of active-sterile {nu} mixing and L in connection with the indications about additional relativistic density in the early Universe, pointed out by BBN, CMB and LSS data and the analysis of global {nu} data.

  11. Collective neutrino oscillations and spontaneous symmetry breaking

    CERN Document Server

    Duan, Huaiyu

    2015-01-01

    Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillation...

  12. Characterizing correlations of flow oscillations at bottlenecks

    Science.gov (United States)

    Kretz, Tobias; Wölki, Marko; Schreckenberg, Michael

    2006-02-01

    'Oscillations' occur in quite different kinds of many-particle systems when two groups of particles with different directions of motion meet or intersect at a certain spot. In this work a model of pedestrian motion is presented that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to include observables that can be used to characterize different kinds of oscillations.

  13. Characterizing correlations of flow oscillations at bottlenecks

    OpenAIRE

    Kretz, Tobias; Woelki, Marko; Schreckenberg, Michael

    2006-01-01

    "Oscillations" occur in quite different kinds of many-particle-systems when two groups of particles with different directions of motion meet or intersect at a certain spot. We present a model of pedestrian motion that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to hold observables that can be used to characterize different kinds of oscillations.

  14. Non-Newtonian mechanics of oscillation centers

    Science.gov (United States)

    Dodin, I. Y.; Fisch, N. J.

    2008-10-01

    Classical particles oscillating in high-frequency or static fields effectively exhibit a modified rest mass meff which determines the oscillation center motion. Unlike the true mass, meff depends on the field parameters and can be a nonanalytic function of the particle average velocity and the oscillation energy; hence non-Newtonian "metaplasmas" that permit a new type of plasma maser, signal rectification, frequency doubling, and one-way walls.

  15. Desynchronization of stochastically synchronized chemical oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Snari, Razan; Tinsley, Mark R., E-mail: mark.tinsley@mail.wvu.edu, E-mail: kshowalt@wvu.edu; Faramarzi, Sadegh; Showalter, Kenneth, E-mail: mark.tinsley@mail.wvu.edu, E-mail: kshowalt@wvu.edu [C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045 (United States); Wilson, Dan; Moehlis, Jeff [Department of Mechanical Engineering, University of California, Santa Barbara, California 93106 (United States); Netoff, Theoden Ivan [Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2015-12-15

    Experimental and theoretical studies are presented on the design of perturbations that enhance desynchronization in populations of oscillators that are synchronized by periodic entrainment. A phase reduction approach is used to determine optimal perturbation timing based upon experimentally measured phase response curves. The effectiveness of the perturbation waveforms is tested experimentally in populations of periodically and stochastically synchronized chemical oscillators. The relevance of the approach to therapeutic methods for disrupting phase coherence in groups of stochastically synchronized neuronal oscillators is discussed.

  16. Bloch oscillations of path-entangled photons.

    Science.gov (United States)

    Bromberg, Yaron; Lahini, Yoav; Silberberg, Yaron

    2010-12-31

    We show that when photons in N-particle path-entangled |N,0)+|0,N) or N00N states undergo Bloch oscillations, they exhibit a periodic transition between spatially bunched and antibunched states. The period of the bunching-antibunching oscillation is N times faster than the period of the oscillation of the photon density, manifesting the unique coherence properties of N00N states. The transition occurs even when the photons are well separated in space.

  17. FORCED OSCILLATIONS IN NONLINEAR FEEDBACK CONTROL SYSTEM

    Science.gov (United States)

    Since a nonlinear feedback control system may possess more than one type of forced oscillations, it is highly desirable to investigate the type of...method for finding the existence of forced oscillations and response curve characteristics of a nonlinear feedback control system by means of finding the...second order feedback control system are investigated; the fundamental frequency forced oscillation for a higher order system and the jump resonance

  18. Coupled oscillator model of the dopaminergic neuron of the substantia nigra.

    Science.gov (United States)

    Wilson, C J; Callaway, J C

    2000-05-01

    Calcium imaging using fura-2 and whole cell recording revealed the effective location of the oscillator mechanism on dopaminergic neurons of the substantia nigra, pars compacta, in slices from rats aged 15-20 days. As previously reported, dopaminergic neurons fired in a slow rhythmic single spiking pattern. The underlying membrane potential oscillation survived blockade of sodium currents with TTX and was enhanced by blockade of voltage-sensitive potassium currents with TEA. Calcium levels increased during the subthreshold depolarizing phase of the membrane potential oscillation and peaked at the onset of the hyperpolarizing phase as expected if the pacemaker potential were due to a low-threshold calcium current and the hyperpolarizing phase to calcium-dependent potassium current. Calcium oscillations were synchronous in the dendrites and soma and were greater in the dendrites than in the soma. Average calcium levels in the dendrites overshot steady-state levels and decayed over the course of seconds after the oscillation was resumed after having been halted by hyperpolarizing currents. Average calcium levels in the soma increased slowly, taking many cycles to achieve steady state. Voltage clamp with calcium imaging revealed the voltage dependence of the somatic calcium current without the artifacts of incomplete spatial voltage control. This showed that the calcium current had little or no inactivation and was half-maximal at -40 to -30 mV. The time constant of calcium removal was measured by the return of calcium to resting levels and depended on diameter. The calcium sensitivity of the calcium-dependent potassium current was estimated by plotting the slow tail current against calcium concentration during the decay of calcium to resting levels at -60 mV. A single compartment model of the dopaminergic neuron consisting of a noninactivating low-threshold calcium current, a calcium-dependent potassium current, and a small leak current reproduced most features of the

  19. First experimental demonstration of a Self-Oscillating Fluidic Heat Engine (SOFHE) with piezoelectric power generation

    Science.gov (United States)

    Monin, T.; Tessier-Poirier, A.; Léveillé, E.; Juneau-Fecteau, A.; Skotnicki, T.; Formosa, F.; Monfray, S.; Fréchette, L. G.

    2016-11-01

    In this paper, we present the working principle and first experimental demonstration of an innovative approach to harvest low-quality heat sources, the Self-Oscillating Fluidic Heat Engine (SOFHE). Thermal energy is first converted into pressure pulsations by a selfexcited thermo-fluidic oscillator driven by periodic phase change of a fluid in an enclosed channel. A piezoelectric membrane then converts this mechanical energy into an electrical power. After describing the working principle, an experimental demonstration is presented. The P-V diagram of this new thermodynamic cycle is measured, showing a mechanical power of 3.3mW. Combined with a piezoelectric spiral membrane, the converted electrical power generation achieved is close to 1μ W in a 1MΩ load. This work sets the basis for future development of this new type of heat engine for waste heat recovery and to power wireless sensors.

  20. Introduction to classical and quantum harmonic oscillators

    CERN Document Server

    Bloch, Sylvan C

    2013-01-01

    From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con

  1. High Reliability Oscillators for Terahertz Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...

  2. Optimal parameters uncoupling vibration modes of oscillators

    CERN Document Server

    Le, Khanh Chau

    2016-01-01

    A novel optimization concept for an oscillator with two degrees of freedom is proposed. By using specially defined motion ratios, we control the action of springs and dampers to each degree of freedom of the oscillator. If the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized, then the optimal motion ratios uncouple vibration modes. The same result holds true for the dissipative oscillator. The application to optimal design of vehicle suspension is discussed.

  3. Energetics of Synchronization in Coupled Oscillators

    CERN Document Server

    Izumida, Yuki; Seifert, Udo

    2016-01-01

    We formulate the energetics of synchronization in coupled oscillators by unifying the nonequilibrium aspects with the nonlinear dynamics via stochastic thermodynamics. We derive a concise and universal expression of the energy dissipation rate using nonlinear-dynamics quantities characterizing synchronization, and elucidate how synchronization/desynchronization between the oscillators affects it. We apply our theory to hydrodynamically-coupled Stokes spheres rotating on circular trajectories that may be interpreted as the simplest model of synchronization of coupled oscillators in a biological system, revealing that the oscillators gain the ability to do more work on the surrounding fluid as the degree of phase synchronization increases.

  4. Kozai-Lidov Oscillations of Circumstellar Disks

    Science.gov (United States)

    Lubow, Stephen H.; Fu, Wen; Martin, Rebecca G.

    2015-01-01

    It has been known for over 50 years that the orbit of an object in a binary system can undergo strong tilt and eccentricity oscillations. This effect, known as the Kozai-Lidov effect, may explain several observed astronomical phenomena, including the high eccentricities observed for some extra-solar planets. Martin et al. 2014 recently reported simulation results showing that fluid disks can undergo Kozai-Lidov oscillations. Such oscillations can have important consequences on disk and planet evolution. We have continued investigating the conditions for which such oscillations are possible.

  5. Electronically tunable phase locked loop oscillator

    Science.gov (United States)

    Balasis, M.; Davis, M. R.; Jackson, C. R.

    1982-02-01

    This report describes the design and development of a low noise, high power, variable oscillator incorporating a high 'Q' electronically tunable resonator as the frequency determining element. The VCO provides improved EMC performance in phase locked synthesizers which are a part of communications equipments. The oscillator combines a low noise VMOS transistor with the selectivity and out-of-band attenuation of a coaxial resonator to provide superior EMC performance. Several oscillator designs were examined and the basis for the final configuration is presented. Oscillator noise is discussed and models for analysis are explained. A brass board model was constructed and tested and the technical results are presented.

  6. Waves and oscillations in nature an introduction

    CERN Document Server

    Narayanan, A Satya

    2015-01-01

    Waves and oscillations are found in large scales (galactic) and microscopic scales (neutrino) in nature. Their dynamics and behavior heavily depend on the type of medium through which they propagate.Waves and Oscillations in Nature: An Introduction clearly elucidates the dynamics and behavior of waves and oscillations in various mediums. It presents different types of waves and oscillations that can be observed and studied from macroscopic to microscopic scales. The book provides a thorough introduction for researchers and graduate students in assorted areas of physics, such as fluid dynamics,

  7. Comparison of Methods for Oscillation Detection

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Trangbæk, Klaus

    2006-01-01

    This paper compares a selection of methods for detecting oscillations in control loops. The methods are tested on measurement data from a coal-fired power plant, where some oscillations are occurring. Emphasis is put on being able to detect oscillations without having a system model and without u...... using process knowledge. The tested methods show potential for detecting the oscillations, however, transient components in the signals cause false detections as well, motivating usage of models in order to remove the expected signals behavior....

  8. Scleronomic holonomic constraints and conservative nonlinear oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Munoz, R; Gonzalez-Garcia, G; Izquierdo-De La Cruz, E Izquierdo-De La [Universidad Autonoma de la Ciudad de Mexico, Centro Historico, Fray Servando Teresa de Mier 92, Col Centro, Del Cuauhtemoc, Mexico DF, CP 06080 (Mexico); Fernandez-Anaya, G, E-mail: rodrigo.munoz@uacm.edu.mx, E-mail: gggharper@gmail.com, E-mail: erickidc@gmail.com, E-mail: guillermo.fernandez@uia.mx [Universidad Iberoamericana, Departamento de Fisica y Matematicas, Prolongacon Paseo de de la Reforma 880, Col Lomas de Santa Fe, Del Alvaro Obregn, Mexico DF, CP 01219 (Mexico)

    2011-05-15

    A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present cases in which the effective potential acting on the bead is not analytical around a minimum. The small oscillation approximation cannot be applied to such pathological cases. Nonetheless, these latter instances are studied with other standard techniques.

  9. Quantum entanglement of Pais-Uhlenbeck oscillators

    CERN Document Server

    Dimov, Hristo; Rashkov, Radoslav C; Vetsov, Tsvetan

    2016-01-01

    We study the quantum entanglement of coupled Pais-Uhlenbeck oscillators using the formalism of thermo-field dynamics. The entanglement entropy is computed for the specific cases of two and a ring of $N$ coupled Pais-Uhlenbeck oscillators of fourth order. It is shown that the entanglement entropy depends on the temperatures, frequencies and coupling parameters of the different degrees of freedom corresponding to harmonic oscillators. Finally, we advert to the information geometry theory by calculating the Fisher information metric for the considered system of coupled oscillators.

  10. Quantum oscillations in superconductors in magnetic field

    Science.gov (United States)

    Gvozdikov, Vladimir M.; Gvozdikova, Mariya V.

    2000-07-01

    The Aharonov-Bohm oscillations (ABO) of the free energy, the critical temperature, and the magnetic susceptibility in a stack of hollow mesoscopic cylinders are calculated. It is shown that sinusoidal (in flux) ABO crosses over to the parabolic Little-Parks oscillations (LPO) when the diameter of cylinders exceeds the coherence length. The exponential temperature behaviour of the magnetic susceptibility is like that found in Ag cylinders with thin Nb coating [Czech. J. Physics 46 (1996) 2317]. The formal analogy between oscillations of the free energy in the Aharonov-Bohm system in question and the de Haas-van Alphen oscillations (dHvAO) in layered superconductors is discussed.

  11. Dynamics of Coupled Quantum-Classical Oscillators

    Institute of Scientific and Technical Information of China (English)

    HE Wei-Zhong; XU Liu-Su; ZOU Feng-Wu

    2004-01-01

    @@ The dynamics of systems consisting of coupled quantum-classical oscillators is numerically investigated. It is shown that, under certain conditions, the quantum oscillator exhibits chaos. When the mass of the classical oscillator increases, the chaos will be suppressed; if the energy of the system and/or the coupling strength between the two oscillators increases, chaotic behaviour of the system appears. This result will be helpful to understand the probability of the emergence of quantum chaos and may be applied to explain the spectra of complex atoms qualitatively.

  12. Coupled oscillators with parity-time symmetry

    Science.gov (United States)

    Tsoy, Eduard N.

    2017-02-01

    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.

  13. CPT-Odd resonances in neutrino oscillations

    Science.gov (United States)

    Barger; Pakvasa; Weiler; Whisnant

    2000-12-11

    We consider the consequences for future neutrino factory experiments of small CPT-odd interactions in neutrino oscillations. The nu(&mgr;)-->nu(&mgr;) and nu;(&mgr;)-->nu;(&mgr;) survival probabilities at a baseline L = 732 km can test for CPT-odd contributions at orders of magnitude better sensitivity than present neutrino sector limits. Interference between the CPT-violating interaction and CPT-even mass terms in the Lagrangian can lead to a resonant enhancement of the oscillation amplitude. For oscillations in matter, a simultaneous enhancement of both neutrino and antineutrino oscillation amplitudes is possible.

  14. Microdroplet oscillations during optical pulling

    CERN Document Server

    Ellingsen, Simen Å

    2011-01-01

    It was recently shown theoretically that it is possible to pull a spherical dielectric body towards the source of a laser beam [Nature Photonics {\\bf 5}, 531 (2011)], a result with immediate consequences to optical manipulation of small droplets. Optical pulling can be realised e.g.\\ using a diffraction free Bessel beam, and is expected to be of great importance in manipulation of microscopic droplets in micro- and nanofluidics. Compared to conventional optical pushing, however, the radio of optical net force to stress acting on a droplet is much smaller, increasing the importance of oscillations. We describe the time-dependent surface deformations of a water microdroplet under optical pulling to linear order in the deformation. Shape oscillations have a lifetime in the order of microseconds for droplet radii of a few micrometers. The force density acting on the initially spherical droplet is strongly peaked near the poles on the beam axis, causing the deformations to take the form of jet-like protrusions.

  15. Cardiogenic oscillation induced ventilator autotriggering

    Directory of Open Access Journals (Sweden)

    Narender Kaloria

    2015-01-01

    Full Text Available Cardiogenic oscillation during mechanical ventilation can auto-trigger the ventilator resembling patient initiated breadth. This gives a false sense of intact respiratory drive and determination brain death, even if other tests are positive, is not appropriate in such a situation. It will prolong the ICU stay and confound the brain-death determination. In this case report, we describe a 35 year old man who was brought to the hospital after many hours of critical delay following multiple gun shot injuries. The patient suffered a cardiac arrest while on the way from another hospital. After an emergency laparotomy, patient was shifted to Intensive Care Unit (ICU with Glasgow Coma Scale (GCS score of E1VTM1 and was mechanically ventilated. Despite absence of brainstem reflexes, the ventilator continued to be triggered on continuous positive airway pressure (CPAP mode and the patient maintained normal oxygen saturation and acceptable levels of carbon dioxide. An apnoea test confirmed absent respiratory drive. Ventilatory waveform graph analysis, revealed cardiogenic oscillation as the cause for autotrigerring.

  16. Neutrino Oscillations: A Global Analysis

    CERN Document Server

    Fogli, G L; Marrone, A; Montanino, D; Palazzo, A; Rotunno, A M

    2003-01-01

    We review the status of the neutrino oscillation physics (as of June 2003), with a particular emphasis on the present knowledge of the neutrino mass-mixing parameters in a three generation approach. We consider first the nu_mu-->nu_tau flavor transitions of atmospheric neutrinos. It is found that standard oscillations provide the best description of the SK+K2K data, and that the associated mass-mixing parameters are determined at 1 sigma (and dof=1) as: Delta m^2=(2.6 +-0.4) x 10^-3 eV^2 and sin^2(2theta)=1.00+0.00-0.05. Such indications, presently dominated by SK, could be strengthened by further K2K data. Then we analyze the energy spectrum of reactor neutrino events recently observed at KamLAND and combine them with solar and terrestrial neutrino data. We find that the solution to the solar neutrino problem at large mixing angle (LMA) is basically split into two sub-regions, that we denote as LMA-I and LMA-II. The LMA-I solution, characterized by lower values of the squared neutrino mass gap, is favored by...

  17. 椎-基底动脉的应用解剖学研究%Applied anatomy research of vertebral basilar artery

    Institute of Scientific and Technical Information of China (English)

    尹金鹏

    2015-01-01

    目的:对椎-基底动脉的应用解剖学进行研究分析,为颈椎手术治疗提供依据。方法选取当地实验中心的15具成人尸体的头部标本进行研究,对标本进行灌注和解剖,观察右侧和左侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径,比较右侧和左侧大脑后动脉与基底动脉、小脑上动脉与基底动脉、小脑下后动脉与椎动脉、小脑下前动脉与基底动脉、锁骨下动脉与椎动脉的夹角,同时对比右侧和左侧大脑后动脉起始处外径、小脑上动脉起始处外径、小脑下前动脉起始处外径、小脑下后动脉起始处外径。结果右侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径均低于左侧椎动脉穿越第六颈椎处外径和椎动脉起始处外径,差异具有统计学意义(P<0.05)。右侧大脑后动脉与基底动脉、小脑上动脉与基底动脉、锁骨下动脉与椎动脉的夹角高于左侧锁骨下动脉与椎动脉的夹角,而右侧小脑下后动脉与椎动脉、小脑下前动脉与基底动脉夹角低于左侧小脑下后动脉与椎动脉、小脑下前动脉与基底动脉夹角,差异具有统计学意义(P<0.05)。右侧小脑下前动脉起始处外径高于左侧小脑下前动脉起始处外径,差异具有统计学意义(P<0.05)。结论椎动脉、椎基底动脉、小脑下前动脉起始处外径左、右两侧起始处的夹角存在一定的差异性,呈现出不对称性,这对颈椎外科手术及血管介入治疗具有重要的指导作用。%Objective To study applied anatomy of vertebral basilar artery and provide basis for cervical spine surgery. Methods choose 15 adult cadavers at local experiment center and study their head specimens by perfusion and anatomy, and o bserve external diameter of part of right and left vertebral artery crossing the 6th cervical vertebra, and starting point of vertebra l artery, and compare intersection angle between

  18. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T. (Inventor); Sahimi, Muhammad (Inventor); Fayyaz-Najafi, Babak (Inventor); Harale, Aadesh (Inventor); Park, Byoung-Gi (Inventor); Liu, Paul K. T. (Inventor)

    2011-01-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  19. Oxygen transport membrane

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

  20. Ionene membrane battery separator

    Science.gov (United States)

    Moacanin, J.; Tom, H. Y.

    1969-01-01

    Ionic transport characteristics of ionenes, insoluble membranes from soluble polyelectrolyte compositions, are studied for possible application in a battery separator. Effectiveness of the thin film of separator membrane essentially determines battery lifetime.

  1. Composite zeolite membranes

    Science.gov (United States)

    Nenoff, Tina M.; Thoma, Steven G.; Ashley, Carol S.; Reed, Scott T.

    2002-01-01

    A new class of composite zeolite membranes and synthesis techniques therefor has been invented. These membranes are essentially defect-free, and exhibit large levels of transmembrane flux and of chemical and isotopic selectivity.

  2. Hybrid adsorptive membrane reactor

    Science.gov (United States)

    Tsotsis, Theodore T.; Sahimi, Muhammad; Fayyaz-Najafi, Babak; Harale, Aadesh; Park, Byoung-Gi; Liu, Paul K. T.

    2011-03-01

    A hybrid adsorbent-membrane reactor in which the chemical reaction, membrane separation, and product adsorption are coupled. Also disclosed are a dual-reactor apparatus and a process using the reactor or the apparatus.

  3. Atom-assisted quadrature squeezing of a mechanical oscillator inside a dispersive cavity

    Science.gov (United States)

    Biswas, Asoka; Chauhan, Anil Kumar

    2016-05-01

    Measurement of position of a mesoscopic harmonic oscillator below standard quantum limit in cavity optomechanics has seen a growing interest in recent times. If the oscillator is suspended inside the cavity (with both the mirrors fixed) at a position where the cavity frequency becomes extremum (a membrane-in-the-middle setup), large squeezing can be achieved by conditional measurement of thermal photons; however the cavity decay degrades such squeezing. Here we propose an atom-cavity-oscillator hybrid scheme, in which the effect of cavity decay is eliminated via dispersive coupling of the cavity mode. The atom in Λ configuration is considered to be trapped on either side of the membrane inside the cavity. We show that a considerable amount of squeezing (far beyond the 3 dB limit) can be achieved that is not affected by spontaneous emission of the atom. The squeezing depends upon the initial preparation of the atomic states. Further, the external classical fields, that drive the atomic transition and the cavity mode, control the degree of squeezing and can also lead to a strong effective atom-oscillator coupling. Effect of thermal phonon bath on squeezing is studied in terms of the squeezing spectrum. The results are supported by the detailed analytical calculations.

  4. The dynamics of a capsule in a wall-bounded oscillating shear flow

    CERN Document Server

    Zhu, LaiLai; Brandt, Luca

    2015-01-01

    The motion of an initially spherical capsule in a wall-bounded oscillating shear flow is investigated via an accelerated boundary integral implementation. The neo-Hookean model is used as the constitutive law of the capsule membrane. The maximum wall-normal migration is observed when the oscillation period of the imposed shear is of the order of the relaxation time of the elastic membrane; hence, the optimal capillary number scales with the inverse of the oscillation frequency and the ratio agrees well with the theoretical prediction in the limit of high-frequency oscillation. The migration velocity decreases monotonically with the frequency of the applied shear and the capsule-wall distance. We report a significant correlation between the capsule lateral migration and the normal stress difference induced in the flow. The periodic variation of the capsule deformation is roughly in phase with that of the migration velocity and normal stress difference, with twice the frequency of the imposed shear. The maximum...

  5. Persistent sodium current contributes to induced voltage oscillations in locomotor-related hb9 interneurons in the mouse spinal cord.

    Science.gov (United States)

    Ziskind-Conhaim, Lea; Wu, Linying; Wiesner, Eric P

    2008-10-01

    Neurochemically induced membrane voltage oscillations and firing episodes in spinal excitatory interneurons expressing the HB9 protein (Hb9 INs) are synchronous with locomotor-like rhythmic motor outputs, suggesting that they contribute to the excitatory drive of motoneurons during locomotion. Similar to central pattern generator neurons in other systems, Hb9 INs are interconnected via electrical coupling, and their rhythmic activity does not depend on fast glutamatergic synaptic transmission. The primary objective of this study was to determine the contribution of fast excitatory and inhibitory synaptic transmission and subthreshold voltage-dependent currents to the induced membrane oscillations in Hb9 INs in the postnatal mouse spinal cord. The non-N-methyl-D-aspartate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) reduced the amplitude of voltage oscillations but did not alter their frequency. CNQX suppressed rhythmic motor activity. Blocking glycine and GABAA receptor-mediated inhibitory synapses as well as cholinergic transmission did not change the properties of CNQX-resistant membrane oscillations. However, disinhibition triggered new episodes of slow motor bursting that were not correlated with induced locomotor-like rhythms in Hb9 INs. Our observations indicated that fast excitatory and inhibitory synaptic inputs did not control the frequency of induced rhythmic activity in Hb9 INs. We next examined the contribution of persistent sodium current (INaP) to subthreshold membrane oscillations in the absence of primary glutamatergic, GABAergic and glycinergic synaptic drive to Hb9 INs. Low concentrations of riluzole that blocked the slow-inactivating component of sodium current gradually suppressed the amplitude and reduced the frequency of voltage oscillations. Our finding that INaP regulates locomotor-related rhythmic activity in Hb9 INs independently of primary synaptic transmission supports the concept that these neurons constitute an

  6. Oscillating layer thickness and vortices generated in oscillation of finite plate

    Science.gov (United States)

    Sin, V. K.; Wong, I. K.

    2016-06-01

    Moving mesh strategy is used in the model of flow induced by oscillating finite plate through software - COMSOL Multiphysics. Flow is assumed to be laminar and arbitrary Lagrangian-Eulerian method is used for moving mesh in the simulation. Oscillating layer thickness is found which is different from the analytical solution by 2 to 3 times depends on the oscillating frequency. Vortices are also observed near the oscillating finite plate because of the edge effect of the finite plate.

  7. Discrete Parametric Oscillation and Nondiffracting Beams in a Glauber-Fock Oscillator

    CERN Document Server

    Oztas, Z

    2016-01-01

    We consider a Glauber-Fock oscillator and show that diffraction can be managed. We show how to design arrays of waveguides where light beams experience zero diffraction. We find an exact analytical family of nondiffracting localized solution. We predict discrete parametric oscillation in the Glauber-Fock oscillator.

  8. Stirring and mixing effects on oscillations and inhomogeneities in the minimal bromate oscillator

    Science.gov (United States)

    Dutt, A. K.; Menzinger, M.

    1999-04-01

    Stirring and mixing effects on the oscillations and inhomogeneities in the bromate-bromide-cerous system (minimal bromate oscillator) have been investigated in a continuously fed stirred tank reactor (CSTR). A movable microelectrode is used to monitor the inhomogeneities inside the CSTR in an oscillating phase. The results are explained in terms of the theory of imperfect mixing.

  9. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes control...

  10. Membrane contactor applications

    NARCIS (Netherlands)

    Klaassen, R.; Feron, P.H.M.; Jansen, A.

    2008-01-01

    In a membrane contactor the membrane separation is completely integrated with an extraction or absorption operation in order to exploit the benefits of both technologies fully. Membrane contactor applications that have been developed can be found in both water and gas treatment. Several recently dev

  11. Emissivity of freestanding membranes with thin metal coatings

    Energy Technology Data Exchange (ETDEWEB)

    Zwol, P. J. van, E-mail: Pieter-jan.van.zwol@asml.com; Vles, D. F.; Voorthuijzen, W. P.; Péter, M.; Vermeulen, H.; Zande, W. J. van der [ASML Netherlands B.V., De Run 6501, 5504 DR Veldhoven (Netherlands); Sturm, J. M.; Kruijs, R. W. E. van de; Bijkerk, F. [Industrial Focus Group XUV Optics, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500 AE Enschede (Netherlands)

    2015-12-07

    Freestanding silicon nitride membranes with thicknesses down to a few tens of nanometers find use as TEM windows or soft X-ray spectral purity filters. As the thickness of a membrane decreases, emissivity vanishes, which limits radiative heat emission and resistance to heat loads. We show that thin metal layers with thicknesses in the order of 1 nm enhance the emissivity of thin membranes by two to three orders of magnitude close to the theoretical limit of 0.5. This considerably increases thermal load capacity of membranes in vacuum environments. Our experimental results are in line with classical theory in which we adapt thickness dependent scattering terms in the Drude and Lorentz oscillators.

  12. Tracking membrane protein association in model membranes.

    Directory of Open Access Journals (Sweden)

    Myriam Reffay

    Full Text Available Membrane proteins are essential in the exchange processes of cells. In spite of great breakthrough in soluble proteins studies, membrane proteins structures, functions and interactions are still a challenge because of the difficulties related to their hydrophobic properties. Most of the experiments are performed with detergent-solubilized membrane proteins. However widely used micellar systems are far from the biological two-dimensions membrane. The development of new biomimetic membrane systems is fundamental to tackle this issue.We present an original approach that combines the Fluorescence Recovery After fringe Pattern Photobleaching technique and the use of a versatile sponge phase that makes it possible to extract crucial informations about interactions between membrane proteins embedded in the bilayers of a sponge phase. The clear advantage lies in the ability to adjust at will the spacing between two adjacent bilayers. When the membranes are far apart, the only possible interactions occur laterally between proteins embedded within the same bilayer, whereas when membranes get closer to each other, interactions between proteins embedded in facing membranes may occur as well.After validating our approach on the streptavidin-biotinylated peptide complex, we study the interactions between two membrane proteins, MexA and OprM, from a Pseudomonas aeruginosa efflux pump. The mode of interaction, the size of the protein complex and its potential stoichiometry are determined. In particular, we demonstrate that: MexA is effectively embedded in the bilayer; MexA and OprM do not interact laterally but can form a complex if they are embedded in opposite bilayers; the population of bound proteins is at its maximum for bilayers separated by a distance of about 200 A, which is the periplasmic thickness of Pseudomonas aeruginosa. We also show that the MexA-OprM association is enhanced when the position and orientation of the protein is restricted by the

  13. Interplay of intrinsic and synaptic conductances in the generation of high-frequency oscillations in interneuronal networks with irregular spiking.

    Directory of Open Access Journals (Sweden)

    Fabiano Baroni

    2014-05-01

    Full Text Available High-frequency oscillations (above 30 Hz have been observed in sensory and higher-order brain areas, and are believed to constitute a general hallmark of functional neuronal activation. Fast inhibition in interneuronal networks has been suggested as a general mechanism for the generation of high-frequency oscillations. Certain classes of interneurons exhibit subthreshold oscillations, but the effect of this intrinsic neuronal property on the population rhythm is not completely understood. We study the influence of intrinsic damped subthreshold oscillations in the emergence of collective high-frequency oscillations, and elucidate the dynamical mechanisms that underlie this phenomenon. We simulate neuronal networks composed of either Integrate-and-Fire (IF or Generalized Integrate-and-Fire (GIF neurons. The IF model displays purely passive subthreshold dynamics, while the GIF model exhibits subthreshold damped oscillations. Individual neurons receive inhibitory synaptic currents mediated by spiking activity in their neighbors as well as noisy synaptic bombardment, and fire irregularly at a lower rate than population frequency. We identify three factors that affect the influence of single-neuron properties on synchronization mediated by inhibition: i the firing rate response to the noisy background input, ii the membrane potential distribution, and iii the shape of Inhibitory Post-Synaptic Potentials (IPSPs. For hyperpolarizing inhibition, the GIF IPSP profile (factor iii exhibits post-inhibitory rebound, which induces a coherent spike-mediated depolarization across cells that greatly facilitates synchronous oscillations. This effect dominates the network dynamics, hence GIF networks display stronger oscillations than IF networks. However, the restorative current in the GIF neuron lowers firing rates and narrows the membrane potential distribution (factors i and ii, respectively, which tend to decrease synchrony. If inhibition is shunting instead

  14. Water Channels Are Involved in Stomatal Oscillations Encoded by Parameter-Specific Cytosolic Calcium Oscillations

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Earlier studies have shown that various stimuli can induce specific cytosolic calcium ([Ca2+]cyt) oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca2+]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean (Vicia faba L.)was used and a rapid ion-exchange treatment with two shifting buffers differing in K+ and Ca2+ concentrations was applied. The treatment for five transients at a 10-min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation is encoded by parameter-specific [Ca2+]cyt oscillation: the parameters of [Ca2+]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β-mercaptoethanol (an agent capable of reversing water channel inhibition by HgCl2). Other inhibitory treatments against ion transport (i.e. the application of LaCl3, EGTA, or tetraethylammonium chloride (TEACl))weakly impaired stomatal oscillation when the compounds were added after rapid ion-exchange treatment.If these compounds were added before rapid-ion exchange treatment, the inhibitory effect was much more apparent (except in the case of TEACI). The results of the present study suggest that water channels are involved in stomatal oscillation as a downstream element of [Ca2+]cyt oscillation signaling.

  15. Cooperative Effects of Noise and Coupling on Stochastic Dynamics of a Membrane-Bulk Coupling Model

    Institute of Scientific and Technical Information of China (English)

    TANG Jun; JIA Ya; YI Ming

    2009-01-01

    Based on a membrane-bulk coupling cell model proposed by Gomez-Marin et al. [ Phys. Rev. Lett. 98 (2007) 168303], the cooperative effects of noise and coupling on the stochastic dynamical behavior are investigated, For parameters in a certain region, the oscillation can be induced by the cooperative effect of noise and coupling. Whether considering the coupling or not, corresponding coherence resonance phenomena are observed. Furthermore, the effects of two coupling parameters, cell size L and coupling intensity k, on the noise-induced oscillation of membranes are studied. Contrary effects of noise are found in and out of the deterministic oscillatory regions.

  16. Posterior decompression and occipitocervical fusion with bone graft in treatment of basilar invagination%后路减压枕颈融合与植骨治疗颅底凹陷症

    Institute of Scientific and Technical Information of China (English)

    王亮; 陈宗雄

    2013-01-01

    Objective To evaluate the efficacy of posterior cervical decompression and occipito-cervical fusion with iliac bone graft and internal fixation for basilar invagination. Methods From January 2010 to March 2012,21 patients( 12 males,9 females )with basilar invagination were given posterior cervical decompression and occipitocervical fusion with iliac bone graft and internal fixation, and all of them received cervical collar fixation for 3 months and rehabilitation exercises. Results The spinal cord in the region of foramen magnum was fully decompressed in all cases according to imaging data after operation. The mean follow-up time was 14 months. The postoperative JOA score was higher than the preoperative one ( 14. 1 points vs. 8. 1 points )with the improvement rate of 67.4% . Conclusion Posterior cervical decompression and occipitocervical fusion with autogenous iliac bone graft and internal fixation is an effective treatment for basilar invagination, which can improve patient's neurological symptoms and the quality of life.%目的 评价颈后路减压后枕颈融合内固定加自体髂骨移植治疗颅底凹陷症的疗效.方法 采用颈后路枕下充分减压+枕颈融合内固定及自体髂骨移植术治疗21例颅底凹陷症患者,术后所有患者给予颈托固定3个月及康复锻炼.结果 本组患者术后影像学检查显示枕骨大孔处脊髓已得到充分减压,平均随访时间14个月,术后JOA评分平均14.1分,明显大于术前的8.1分,改善率为67.4%.结论 颈后路减压后枕颈融合内固定加自体髂骨移植是治疗颅底凹陷症的一种有效方法,可改善患者神经症状,提高生活质量.

  17. 不同结构支架植入蜿蜒型颅内动脉瘤的仿真研究%Simulation of Intervention for Basilar Sinuous Aneurysms with Different Structural Stent

    Institute of Scientific and Technical Information of China (English)

    乔爱科; 顾兆勇; 孟宪龙; 付文宇

    2011-01-01

    Endovascular stents with different stent shapes or wire cross-section shapes have different effects on the hemodynamics of basilar aneurysm. To quantitatively understand the difference, computational fluid dynamics simulation were performed to investigate the hemodynamics of basilar sinuous aneurysms treated with four types of virtual mesh stents with different porosities and different wire cross-section shapes. Results show that the triangle stent with a lower porosity has more superiority than other stents in weakening the impact of blood to the aneurismal wall and decreasing the local high pressure and wall shear stress. The flow resistance of the new stent with a triangle cross-section is different when blood flows in and out of the aneurismal sac, which brings about different hemodynamics in aneurusms after the stent intervention. The stent with a triangle section is more suitable for sinuous basilar aneurysms comparatively. Those results can provide some theoretically guide the structural design of stents.%为了探讨不同结构的血管内支架对颅内复杂动脉瘤的血液动力学特性的影响,针对同一蜿蜒形颅内动脉瘤结构,构建了4种不同的裸支架(截面形状和孔隙率不同),分别植入动脉瘤的有限元模型,进行流体动力学仿真计算,获得了一些血流动力学的定量信息.4种模型中,无论是在减小血流对动脉瘤远端瘤壁冲击,还是在局部高压力的降低以及减小动脉瘤壁面切应力等方面,孔隙率较低的三角形截面的网格支架的效果均优于其他3种模型支架的效果.设计采用的三角形截面支架由于血液流入和流出时的流阻不同,导致该支架植人动脉瘤后对瘤腔血流的影响不同,从而产生了动脉瘤腔内的血流动力学差异.这可以为支架结构设计提供一些理论指导意义.

  18. Activation of a cGMP-sensitive calcium-dependent chloride channel may cause transition from calcium waves to whole-cell oscillations in smooth muscle cells

    DEFF Research Database (Denmark)

    Jacobsen, Jens Christian; Aalkjær, Christian; Nilsson, Holger;

    2007-01-01

    waves sweeping through the cytoplasm when the SR is stimulated to release calcium. A rise in cyclic guanosine monophosphate (cGMP) leads to the experimentally observed transition from waves to whole-cell calcium oscillations. At the same time membrane potential starts to oscillate and the frequency...... approximately doubles. In this transition, the simulated results point to a key role for a recently discovered cGMP-sensitive calcium-dependent chloride channel. This channel depolarizes the membrane in response to calcium released from the SR. In turn, depolarization causes uniform opening of L-type calcium...... onset of oscillations in membrane potential within the individual cell may underlie sudden intercellular synchronization and the appearance of vasomotion. Key words: Vasomotion, Chloride channel, cGMP, Mathematical model, Calcium waves....

  19. Separation membrane development

    Energy Technology Data Exchange (ETDEWEB)

    Lee, M.W. [Savannah River Technology Center, Aiken, SC (United States)

    1998-08-01

    A ceramic membrane has been developed to separate hydrogen from other gases. The method used is a sol-gel process. A thin layer of dense ceramic material is coated on a coarse ceramic filter substrate. The pore size distribution in the thin layer is controlled by a densification of the coating materials by heat treatment. The membrane has been tested by permeation measurement of the hydrogen and other gases. Selectivity of the membrane has been achieved to separate hydrogen from carbon monoxide. The permeation rate of hydrogen through the ceramic membrane was about 20 times larger than Pd-Ag membrane.

  20. Mixed matrix membrane development.

    Science.gov (United States)

    Kulprathipanja, Santi

    2003-03-01

    Two types of mixed matrix membranes were developed by UOP in the late 1980s. The first type includes adsorbent polymers, such as silicalite-cellulose acetate (CA), NaX-CA, and AgX-CA mixed matrix membranes. The silicalite-CA has a CO(2)/H(2) selectivity of 5.15 +/- 2.2. In contrast, the CA membrane has a CO(2)/H(2) selectivity of 0.77 +/- 0.06. The second type of mixed matrix membrane is PEG-silicone rubber. The PEG-silicone rubber mixed matrix membrane has high selectivity for polar gases, such as SO(2), NH(3), and H(2)S.