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Sample records for nuclear shape oscillations

  1. Large amplitude drop shape oscillations

    NASA Technical Reports Server (NTRS)

    Trinh, E. H.; Wang, T. G.

    1982-01-01

    An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.

  2. Sawtooth oscillations in shaped plasmas

    SciTech Connect

    Lazarus, E. A.; Luce, T. C.; Burrell, K. H.; Chu, M. S.; Ferron, J. R.; Hyatt, A. W.; Lao, L. L.; Lohr, J.; Osborne, T. H.; Petty, C. C.; Politzer, P. A.; Prater, R.; Scoville, J. T.; Strait, E. J.; Turnbull, A. D.; Austin, M. E.; Waelbroeck, F. L.; Brennan, D. P.; Jayakumar, R. J.; Makowski, M. A.

    2007-05-15

    The role of interchange and internal kink modes in the sawtooth oscillations is explored by comparing bean- and oval-shaped plasmas. The n=1 instability that results in the collapse of the sawtooth has been identified as a quasi-interchange in the oval cases and the internal kink in the bean shape. The ion and electron temperature profiles are followed in detail through the sawtooth ramp. It is found that electron energy transport rates are very high in the oval and quite low in the bean shape. Ion energy confinement in the oval is excellent and the sawtooth amplitude ({delta}T/T) in the ion temperature is much larger than that of the electrons. The sawtooth amplitudes for ions and electrons are comparable in the bean shape. The measured q profiles in the bean and oval shapes are found to be consistent with neoclassical current diffusion of the toroidal current, and the observed differences in q largely result from the severe differences in electron energy transport. For both shapes the collapse flattens the q profile and after the collapse return to q{sub 0} > or approx. 1. Recent results on intermediate shapes are reported. These shapes show that the electron energy transport improves gradually as the plasma triangularity is increased.

  3. An improved choice of oscillator basis for banana shaped nuclides

    SciTech Connect

    Chasman, R.R.

    1994-03-01

    The question of the appropriate choice of oscillator basis functions for studying exotic nuclear shapes is raised. Difficulties with the conventional choice of oscillator basis states are noted for shapes having a large banana component. A prescription for an improved oscillator basis to study these shapes is given. It can be applied in a more general context. New calculations with this improved basis are presented for the banana deformation mode. The change of basis gives results that improve the prospects of finding states in the banana minimum for many isotopes of Tl, Pb and Bi.

  4. Synchronously pumped nuclear magnetic oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Thrasher, Daniel; Bulatowicz, Michael; Walker, Thad

    2015-05-01

    We present progress towards a synchronously pumped nuclear magnetic oscillator. Alkali frequency shifts and quadrupole shifts are the dominant systematic effects in dual Xe isotope co-magnetometers. By synchronously pumping the Xe nuclei using spin-exchange with an oscillating Rb polarization, the Rb and Xe spins precess transverse to the longitudinal bias field. This configuration is predicted to be insensitive to first order quadrupole interactions and alkali spin-exchange frequency shifts. A key feature that allows co-precession of the Rb and Xe spins, despite a ~ 1000 fold ratio of their gyromagnetic ratios, is to apply the bias field in the form of a sequence of Rb 2 π pulses whose repetition frequency is equal to the Rb Larmor frequency. The 2 π pulses result in an effective Rb magnetic moment of zero, while the Xe precession depends only on the time average of the pulsed field amplitude. Polarization modulation of the pumping light at the Xe NMR frequency allows co-precession of the Rb and Xe spins. We will present our preliminary experimental studies of this new approach to NMR of spin-exchange pumped Xe. Support by the NSF and Northrop Grumman Co.

  5. Nuclear Propelled Vessels and Neutrino Oscillation Experiments

    NASA Astrophysics Data System (ADS)

    Detwiler, J.; Gratta, G.; Tolich, N.; Uchida, Y.

    2002-10-01

    We study the effect of naval nuclear reactors on the study of neutrino oscillations. We find that the presence of naval reactors at unknown locations and times may limit the accuracy of future very long baseline reactor-based neutrino oscillation experiments. At the same time, we argue that a nuclear powered surface ship such as a large Russian icebreaker may provide an ideal source for precision experiments.

  6. A Beam Shape Oscillation Monitor for HERA

    NASA Astrophysics Data System (ADS)

    Afanasyev, O. V.; Baluev, A. B.; Gubrienko, K. I.; Merker, E. A.; Wittenburg, K.; Krouptchenkow, I.

    2006-11-01

    The perfect matching of the injecting beam phase space with the accelerator lattice is a very important problem. Its successful solution allows excluding possible mismatch emittance blow-up and worsening of the beam characteristics, that is necessary to get the highest possible luminosity in hadron accelerators. The mismatch can be controlled by measuring sizes oscillation on the first revolutions of the injected beam at a certain orbit point. Designed for this purpose the construction, acquisition electronics, software controlling of the operation and data processing of such a monitor are described. A first test result with beam is presented.

  7. Vertical vibration and shape oscillation of acoustically levitated water drops

    SciTech Connect

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-09-08

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  8. Vertical vibration and shape oscillation of acoustically levitated water drops

    NASA Astrophysics Data System (ADS)

    Geng, D. L.; Xie, W. J.; Yan, N.; Wei, B.

    2014-09-01

    We present the vertical harmonic vibration of levitated water drops within ultrasound field. The restoring force to maintain such a vibration mode is provided by the resultant force of acoustic radiation force and drop gravity. Experiments reveal that the vibration frequency increases with the aspect ratio for drops with the same volume, which agrees with the theoretical prediction for those cases of nearly equiaxed drops. During the vertical vibration, the floating drops undergo the second order shape oscillation. The shape oscillation frequency is determined to be twice the vibration frequency.

  9. The harmonic oscillator and nuclear physics

    NASA Technical Reports Server (NTRS)

    Rowe, D. J.

    1993-01-01

    The three-dimensional harmonic oscillator plays a central role in nuclear physics. It provides the underlying structure of the independent-particle shell model and gives rise to the dynamical group structures on which models of nuclear collective motion are based. It is shown that the three-dimensional harmonic oscillator features a rich variety of coherent states, including vibrations of the monopole, dipole, and quadrupole types, and rotations of the rigid flow, vortex flow, and irrotational flow types. Nuclear collective states exhibit all of these flows. It is also shown that the coherent state representations, which have their origins in applications to the dynamical groups of the simple harmonic oscillator, can be extended to vector coherent state representations with a much wider range of applicability. As a result, coherent state theory and vector coherent state theory become powerful tools in the application of algebraic methods in physics.

  10. Shape Oscillations of Gas Bubbles With Newtonian Interfacial Rheological Properties

    NASA Technical Reports Server (NTRS)

    Nadim, Ali

    1996-01-01

    The oscillation frequency and damping rate for small-amplitude axisymmetric shape modes of a gas bubble in an ideal liquid are obtained, in the limit when the bubble interface possesses Newtonian interfacial rheology with constant surface shear and dilatational viscosities. Such results permit the latter surface properties to be measured by analyzing experimental data on frequency shift and damping rate of specific shape modes of suspended bubbles in the presence of surfactants.

  11. Modification of shape oscillations of an attached bubble by surfactants

    NASA Astrophysics Data System (ADS)

    Vobecká, L.; Vejražka, J.; Tihon, J.

    2013-04-01

    Surface-active agents (surfactants, e.g. washing agents) strongly modifies properties of gas-liquid interface. We have carried out extensive experiments, in which we study effect of surfactants on the shape oscillations of a bubble, which is attached at a tip of a capillary. In the experiments, shape oscillations of a bubble are invoked by a motion of a capillary, to which the bubble is injected. Decaying oscillations are recorded and their frequency and damping are evaluated. By changing the excitation frequency, three lowest oscillation modes are studied. Experiments were repeated in aqueous solution of several surfactants (terpineol, SDS, CTAB, Triton X-100, Triton X-45) at various concentrations. Generally, these features are observed: Initially a surfactant addition leads to an increase of the oscillation frequency (though surface tension is decreasing); this effect can be attributed to the increasing interfacial elasticity. The decay time of oscillation is strongly decreasing, as a consequence of energy dissipation linked with Marangoni stresses. At a certain critical concentration, frequency decreases abruptly and the decay time passes by a minimum. With further addition of surfactant, frequency decreases, and the decay time slightly lengthens. Above critical micelle concentration, all these parameters stabilize. Interestingly, the critical concentration, at which frequency drop occurs, depends on mode order. This clearly shows that the frequency drop and minimum decay time are not a consequence of some abrupt change of interfacial properties, but are a consequence of some phenomena, which still need to be explained.

  12. Nuclear effects in neutrino oscillation experiments

    SciTech Connect

    Chauhan, S.; Athar, M. Sajjad; Singh, S. K.

    2011-10-06

    We have studied the nuclear medium effects in the neutrino(antineutrino) induced interactions in nuclei which are relevant for present neutrino oscillation experiments in the few GeV energy region. The study is specially focused on calculating the cross sections and the event rates for atmospheric and accelerator neutrino experiments. The nuclear effects are found to be important for the quasielastic lepton production and the charged current incoherent and coherent pion production processes.

  13. Measuring Neutrino Oscillations with Nuclear Reactors

    SciTech Connect

    McKeown, R. D.

    2007-10-26

    Since the first direct observations of antineutrino events by Reines and Cowan in the 1950's, nuclear reactors have been an important tool in the study of neutrino properties. More recently, the study of neutrino oscillations has been a very active area of research. The pioneering observation of oscillations by the KamLAND experiment has provided crucial information on the neutrino mixing matrix. New experiments to study the remaining unknown mixing angle are currently under development. These recent studies and potential future developments will be discussed.

  14. Shapes and oscillations of falling raindrops — A review

    NASA Astrophysics Data System (ADS)

    Szakáll, Miklós; Mitra, Subir K.; Diehl, Karoline; Borrmann, Stephan

    2010-09-01

    Since more than a hundred years ago the deformed shape of raindrops and their oscillations have been observed but investigations are still ongoing as the experimental and numerical techniques are being improved, and the demand from meteorological applications (e.g., weather radars) for more precise characterization of natural raindrops have increased. For laboratory measurements, the realistic simulation of atmospheric conditions is crucial so it is important that drops fall at their terminal velocities and appear as motionless in vertical wind tunnels. Experiments that are performed in fall shafts or vertical wind tunnels are complemented by ground-based and airborne field observations. On the theoretical side, raindrop deformation and oscillations are given by model computations. Comparing model axis ratios with different kinds of measurements allows one to conclude that the dynamic axis ratio of oscillating raindrops can be appropriately obtained from a force balance model. In the size range between 1 and 2.5 mm diameter, which is of great importance from the point of view of radar meteorology, it is still questionable whether the dynamic axis ratios are equal to the equilibrium axis ratios in all cases. Equations which describe the oscillation frequencies of different modes are confirmed by laboratory measurements. Some experimental evidence hints at the co-existence of several modes of oscillations. It is, however, still not completely clear which modes can be active and how the existence of higher modes depends on the raindrop size. In this paper a review of the current knowledge about the time average axis ratio, the oscillation frequencies and modes, and the shape of freely falling raindrops is presented; besides an overview of the adopted experimental techniques is provided, and the remaining open questions are highlighted.

  15. An Osmoregulatory Basis for Shape Oscillations in Regenerating Hydra

    PubMed Central

    Kücken, Michael; Soriano, Jordi; Pullarkat, Pramod A.; Ott, Albrecht; Nicola, Ernesto M.

    2008-01-01

    The freshwater polyp Hydra has considerable regeneration capabilities. A small fragment of tissue excised from an adult animal is sufficient to regenerate an entire Hydra in the course of a few days. During the initial stages of the regeneration process, the tissue forms a hollow sphere. Then the sphere exhibits shape oscillations in the form of repeated cycles of swelling and collapse. We propose a biophysical model for the swelling mechanism. Our model takes the osmotic pressure difference between Hydra's inner and outer media and the elastic forces of the Hydra shell into account. We validate the model by a comprehensive experimental study including variations in initial medium concentrations, Hydra sphere sizes and temperatures. Numerical simulations of the model provide values for the swelling rates that are in agreement with the ones measured experimentally. Based on our results we argue that the shape oscillations are a consequence of Hydra's osmoregulation. PMID:18375512

  16. The origin of star-shaped oscillations of Leidenfrost drops

    NASA Astrophysics Data System (ADS)

    Ma, Xiaolei; Burton, Justin C.

    We experimentally investigate the oscillations of Leidenfrost drops of water, liquid nitrogen, ethanol, methanol, acetone and isopropyl alcohol. The drops levitate on a cushion of evaporated vapor over a hot, curved surface which keeps the drops stationary. We observe star-shaped modes along the periphery of the drop, with mode numbers n = 2 to 13. The number of observed modes is sensitive to the properties of the liquid. The pressure oscillation frequency in the vapor layer under the drop is approximately twice that of the drop frequency, which is consistent with a parametric forcing mechanism. However, the Rayleigh and thermal Marangoni numbers are of order 10,000, indicating that convection should play a dominating role as well. Surprisingly, we find that the wavelength and frequency of the oscillations only depend on the thickness of the liquid, which is twice the capillary length, and do not depend on the mode number, substrate temperature, or the substrate curvature. This robust behavior suggests that the wavelength for the oscillations is set by thermal convection inside the drop, and is less dependent on the flow in the vapor layer under the drop

  17. Antineutrinos from nuclear reactors: recent oscillation measurements

    NASA Astrophysics Data System (ADS)

    Dwyer, D. A.

    2015-02-01

    Nuclear reactors are the most intense man-made source of antineutrinos, providing a useful tool for the study of these particles. Oscillation due to the neutrino mixing angle {{θ }13} is revealed by the disappearance of reactor {{\\bar{ν }}e} over ˜km distances. Use of additional identical detectors located near nuclear reactors reduce systematic uncertainties related to reactor {{\\bar{ν }}e} emission and detector efficiency, significantly improving the sensitivity of oscillation measurements. The Double Chooz, RENO, and Daya Bay experiments set out in search of {{θ }13} using these techniques. All three experiments have recently observed reactor {{\\bar{ν }}e} disappearance, and have estimated values for {{θ }13} of 9.3◦ ± 2.1°, 9.2◦ ± 0.9°, and 8.7◦ ± 0.4° respectively. The energy-dependence of {{\\bar{ν }}e} disappearance has also allowed measurement of the effective neutrino mass difference, \\mid Δ mee2\\mid ≈ \\mid Δ m312\\mid . Comparison with \\mid Δ mμ μ 2\\mid ≈ \\mid Δ m322\\mid from accelerator {{ν }μ } measurements supports the three-flavor model of neutrino oscillation. The current generation of reactor {{\\bar{ν }}e} experiments are expected to reach ˜3% precision in both {{θ }13} and \\mid Δ mee2\\mid . Precise knowledge of these parameters aids interpretation of planned {{ν }μ } measurements, and allows future experiments to probe the neutrino mass hierarchy and possible CP-violation in neutrino oscillation. Absolute measurements of the energy spectra of {{\\bar{ν }}e} deviate from existing models of reactor emission, particularly in the range of 5-7 MeV.

  18. Excitation of muonic molecules ddμ and dtμ by super-intense attosecond soft X-ray laser pulses: Shaped post-laser-pulse muonic oscillations and enhancement of nuclear fusion

    NASA Astrophysics Data System (ADS)

    Bandrauk, André D.; Paramonov, Guennaddi K.

    2014-07-01

    The quantum dynamics of muonic molecular ions ddμ and dtμ excited by linearly polarized along the molecular (z)-axis super-intense laser pulses is studied beyond the Born-Oppenheimer approximation by the numerical solution of the time-dependent Schrödinger equation within a three-dimensional model, including the internuclear distance R and muon coordinates z and ρ. The peak-intensity of the super-intense laser pulses used in our simulations is I0 = 3.51 × 1022 W/cm2 and the wavelength is λl = 5 nm. In both ddμ and dtμ, expectation values and < ρ > of muon demonstrate "post-laser-pulse" oscillations after the ends of the laser pulses. In ddμ post-laser-pulse z-oscillations appear as shaped nonoverlapping "echo-pulses". In dtμ post-laser-pulse muonic z-oscillations appear as comparatively slow large-amplitude oscillations modulated with small-amplitude pulsations. The post-laser-pulse ρ-oscillations in both ddμ and dtμ appear, for the most part, as overlapping "echo-pulses". The post-laser-pulse oscillations do not occur if the Born-Oppenheimer approximation is employed. Power spectra generated due to muonic motion along both optically active z and optically passive ρ degrees of freedom are calculated. The fusion probability in dtμ can be increased by more than 11 times by making use of three sequential super-intense laser pulses. The energy released from the dt fusion in dtμ can by more than 20 GeV exceed the energy required to produce a usable muon and the energy of the laser pulses used to enhance the fusion. The possibility of power production from the laser-enhanced muon-catalyzed fusion is discussed.

  19. Solar Shape Changes and Oscillations from Space (P15)

    NASA Astrophysics Data System (ADS)

    Damé, L.

    2006-11-01

    The diameter was observed to be constant over the last solar cycles and, as such, is not a "proper" solar-terrestrial "climate" indicator. Ground measurements with small telescopes are spurious diffraction and seeing affected, the Maunder Minimum ones of Picard during the XVII century not being an exception. Large instruments (like the 45 cm Gregory's of A. Wittmann in Locarno and Tenerife) that average seeing cells see no variations (< 40 mas) and, as well, space instruments (MDI/SOHO) that are naturally not affected by turbulence. We present the four approaches, Wittmann on ground with large telescopes, Kuhn et al. (2004) who used the six pixels limb data of MDI, Antia (2003) with a completely different method since using the ultra-precise frequency variation of the f-modes, and our approach (Damé and Cugnet, 2006) using seven years of MDI filtergrams data (150 000 photograms and magnetograms). These four careful analyses converge towards the same insignificant variations (below 15 mas for space experiments or even less: 0.6 km, 0.8 mas for the helioseismology approach!). Following Antia, we conclude that: "If a careful analysis is performed, then it turns out that there is no evidence for any variation in the solar radius." There were no theoretical reasons for large solar radius variations and there is no observational evidence for them with consistent ground and space observations. This being said, the radius measurements are of interest for the solar shape changes that might occur along the cycle (sub- surface convective flows?). Radius oscillations (but higher in the atmosphere, further in the UV: 220 nm) might also bring up low order p-modes and, eventually, g-modes if ever accessible. At the level of formation of the 220 nm continuum there is the maximum magnification of the p-modes and intensity oscillations. 220 nm is also the Lyman Alpha absorption region and ozone formation layer. A New Solar Shape and Oscillation Telescope (NSSOT) is proposed and

  20. Nuclear shapes: from earliest ideas to multiple shape coexisting structures

    NASA Astrophysics Data System (ADS)

    Heyde, K.; Wood, J. L.

    2016-08-01

    The concept of the atomic nucleus being characterized by an intrinsic property such as shape came as a result of high precision hyperfine studies in the field of atomic physics, which indicated a non-spherical nuclear charge distribution. Herein, we describe the various steps taken through ingenious experimentation and bold theoretical suggestions that mapped the way for later work in the early 50s by Aage Bohr, Ben Mottelson and James Rainwater. We lay out a long and winding road that marked, in the period of 50s to 70s, the way shell-model and collective-model concepts were reconciled. A rapid increase in both accelerator and detection methods (70s towards the early 2000s) opened new vistas into nuclear shapes, and their coexistence, in various regions of the nuclear mass table. Next, we outline a possible unified view of nuclear shapes: emphasizing decisive steps taken as well as questions remaining, next to the theoretical efforts that could result in an emerging understanding of nuclear shapes, building on the nucleus considered as a strongly interacting system of nucleons as the microscopic starting point.

  1. How adaptation shapes spike rate oscillations in recurrent neuronal networks

    PubMed Central

    Augustin, Moritz; Ladenbauer, Josef; Obermayer, Klaus

    2012-01-01

    Neural mass signals from in-vivo recordings often show oscillations with frequencies ranging from <1 to 100 Hz. Fast rhythmic activity in the beta and gamma range can be generated by network-based mechanisms such as recurrent synaptic excitation-inhibition loops. Slower oscillations might instead depend on neuronal adaptation currents whose timescales range from tens of milliseconds to seconds. Here we investigate how the dynamics of such adaptation currents contribute to spike rate oscillations and resonance properties in recurrent networks of excitatory and inhibitory neurons. Based on a network of sparsely coupled spiking model neurons with two types of adaptation current and conductance-based synapses with heterogeneous strengths and delays we use a mean-field approach to analyze oscillatory network activity. For constant external input, we find that spike-triggered adaptation currents provide a mechanism to generate slow oscillations over a wide range of adaptation timescales as long as recurrent synaptic excitation is sufficiently strong. Faster rhythms occur when recurrent inhibition is slower than excitation and oscillation frequency increases with the strength of inhibition. Adaptation facilitates such network-based oscillations for fast synaptic inhibition and leads to decreased frequencies. For oscillatory external input, adaptation currents amplify a narrow band of frequencies and cause phase advances for low frequencies in addition to phase delays at higher frequencies. Our results therefore identify the different key roles of neuronal adaptation dynamics for rhythmogenesis and selective signal propagation in recurrent networks. PMID:23450654

  2. Shapes and stability of algebraic nuclear models

    NASA Technical Reports Server (NTRS)

    Lopez-Moreno, Enrique; Castanos, Octavio

    1995-01-01

    A generalization of the procedure to study shapes and stability of algebraic nuclear models introduced by Gilmore is presented. One calculates the expectation value of the Hamiltonian with respect to the coherent states of the algebraic structure of the system. Then equilibrium configurations of the resulting energy surface, which depends in general on state variables and a set of parameters, are classified through the Catastrophe theory. For one- and two-body interactions in the Hamiltonian of the interacting Boson model-1, the critical points are organized through the Cusp catastrophe. As an example, we apply this Separatrix to describe the energy surfaces associated to the Rutenium and Samarium isotopes.

  3. Visualization of the Mode Shapes of Pressure Oscillation in a Cylindrical Cavity

    SciTech Connect

    He, Xin; Qi, Yunliang; Wang, Zhi; Wang, Jianxin; Shuai, Shijin; Tao, Ling

    2015-06-08

    Our work describes a novel experimental method to visualize the mode shapes of pressure oscillation in a cylindrical cavity. Acoustic resonance in a cavity is a grand old problem that has been under investigation (using both analytical and numerical methods) for more than a century. In this article, a novel method based on high speed imaging of combustion chemiluminescence was presented to visualize the mode shapes of pressure oscillation in a cylindrical cavity. By generating high-temperature combustion gases and strong pressure waves simultaneously in a cylindrical cavity, the pressure oscillation can be inferred due to the chemiluminescence emissions of the combustion products. We can then visualized the mode shapes by reconstructing the images based on the amplitudes of the luminosity spectrum at the corresponding resonant frequencies. Up to 11 resonant mode shapes were clearly visualized, each matching very well with the analytical solutions.

  4. Non-linear shape oscillations of rising drops and bubbles: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Lalanne, Benjamin; Abi Chebel, Nicolas; Vejražka, Jiří; Tanguy, Sébastien; Masbernat, Olivier; Risso, Frédéric

    2015-12-01

    This paper focuses on shape-oscillations of a gas bubble or a liquid drop rising in another liquid. The bubble/drop is initially attached to a capillary and is released by a sudden motion of that capillary, resulting in the rise of the bubble/drop along with the oscillations of its shape. Such experimental conditions make difficult the interpretation of the oscillation dynamics with regard to the standard linear theory of oscillation because (i) amplitude of deformation is large enough to induce nonlinearities, (ii) the rising motion may be coupled with the oscillation dynamics, and (iii) clean conditions without residual surfactants may not be achieved. These differences with the theory are addressed by comparing experimental observation with numerical simulation. Simulations are carried out using Level-Set and Ghost-Fluid methods with clean interfaces. The effect of the rising motion is investigated by performing simulations under different gravity conditions. Using a decomposition of the bubble/drop shape into a series of spherical harmonics, experimental and numerical time evolutions of their amplitudes are compared. Due to large oscillation amplitude, non-linear couplings between the modes are evidenced from both experimental and numerical signals; modes of lower frequency influence modes of higher frequency, whereas the reverse is not observed. Nevertheless, the dominant frequency and overall damping rate of the first five modes are in good agreement with the linear theory. Effect of the rising motion on the oscillations is globally negligible, provided the mean shape of the oscillation remains close to a sphere. In the drop case, despite the residual interface contamination evidenced by a reduction in the terminal velocity, the oscillation dynamics is shown to be unaltered compared to that of a clean drop.

  5. Oscillating and star-shaped drops levitated by an airflow.

    PubMed

    Bouwhuis, Wilco; Winkels, Koen G; Peters, Ivo R; Brunet, Philippe; van der Meer, Devaraj; Snoeijer, Jacco H

    2013-08-01

    We investigate the spontaneous oscillations of drops levitated above an air cushion, eventually inducing a breaking of axisymmetry and the appearance of "star drops". This is strongly reminiscent of the Leidenfrost stars that are observed for drops floating above a hot substrate. The key advantage of this work is that we inject the airflow at a constant rate below the drop, thus eliminating thermal effects and allowing for a better control of the flow rate. We perform experiments with drops of different viscosities and observe stable states, oscillations, and chimney instabilities. We find that for a given drop size the instability appears above a critical flow rate, where the latter is largest for small drops. All these observations are reproduced by numerical simulations, where we treat the drop using potential flow and the gas as a viscous lubrication layer. Qualitatively, the onset of instability agrees with the experimental results, although the typical flow rates are too large by a factor 10. Our results demonstrate that thermal effects are not important for the formation of star drops and strongly suggest a purely hydrodynamic mechanism for the formation of Leidenfrost stars. PMID:24032934

  6. Evolved Colloidosomes Undergoing Cell-like Autonomous Shape Oscillations with Buckling.

    PubMed

    Tamate, Ryota; Ueki, Takeshi; Yoshida, Ryo

    2016-04-18

    In living systems, there are many autonomous and oscillatory phenomena to sustain life, such as heart contractions and breathing. At the microscopic level, oscillatory shape deformations of cells are often observed in dynamic behaviors during cell migration and morphogenesis. In many cases, oscillatory behaviors of cells are not simplistic but complex with diverse deformations. So far, we have succeeded in developing self-oscillating polymers and gels, but complex oscillatory behaviors mimicking those of living cells have yet to be reproduced. Herein, we report a cell-like hollow sphere composed of self-oscillating microgels, that is, a colloidosome, that exhibits drastic shape oscillation in addition to swelling/deswelling oscillations driven by an oscillatory reaction. The resulting oscillatory profile waveform becomes markedly more complex than a conventional one. Especially for larger colloidosomes, multiple buckling and moving buckling points are observed to be analogous to cells. PMID:26960167

  7. Investigation of Liquid Surface Rheology of Surfactant Solutions by Droplet Shape Oscillations: Experiments

    PubMed

    Tian; Holt; Apfel

    1997-03-01

    The experimental results of droplet shape oscillations are reported and applied to the analysis of surface rheological properties of surfactant solutions. An acoustic levitation technique is used to suspend the test drop in air and excite it into quadrupole shape oscillations. The equilibrium surface tension, Gibbs elasticity, and surface dilatational viscosity are determined from the measurements of droplet static shape under different levitation sound pressure, oscillation frequency, and free damping constant. Aqueous solutions of sodium dodecyl sulfate, dodecyltrimethylammonium bromide, and n-octyl beta-d-glucopyranoside are tested with this system. The concentrations of the solutions are below the critical micelle concentration. For these solutions it is found that the surface Gibbs elasticity approaches a maximum at a moderate concentration, and its value is less than that directly calculated from the state equation of a static liquid surface. The surface dilatational viscosity is found to be in a range around 0.1 cps. PMID:9245310

  8. Recent advances in understanding nuclear size and shape.

    PubMed

    Mukherjee, Richik N; Chen, Pan; Levy, Daniel L

    2016-04-25

    Size and shape are important aspects of nuclear structure. While normal cells maintain nuclear size within a defined range, altered nuclear size and shape are associated with a variety of diseases. It is unknown if altered nuclear morphology contributes to pathology, and answering this question requires a better understanding of the mechanisms that control nuclear size and shape. In this review, we discuss recent advances in our understanding of the mechanisms that regulate nuclear morphology, focusing on nucleocytoplasmic transport, nuclear lamins, the endoplasmic reticulum, the cell cycle, and potential links between nuclear size and size regulation of other organelles. We then discuss the functional significance of nuclear morphology in the context of early embryonic development. Looking toward the future, we review new experimental approaches that promise to provide new insights into mechanisms of nuclear size control, in particular microfluidic-based technologies, and discuss how altered nuclear morphology might impact chromatin organization and physiology of diseased cells. PMID:26963026

  9. Joint modeling of cell and nuclear shape variation

    PubMed Central

    Johnson, Gregory R.; Buck, Taraz E.; Sullivan, Devin P.; Rohde, Gustavo K.; Murphy, Robert F.

    2015-01-01

    Modeling cell shape variation is critical to our understanding of cell biology. Previous work has demonstrated the utility of nonrigid image registration methods for the construction of nonparametric nuclear shape models in which pairwise deformation distances are measured between all shapes and are embedded into a low-dimensional shape space. Using these methods, we explore the relationship between cell shape and nuclear shape. We find that these are frequently dependent on each other and use this as the motivation for the development of combined cell and nuclear shape space models, extending nonparametric cell representations to multiple-component three-dimensional cellular shapes and identifying modes of joint shape variation. We learn a first-order dynamics model to predict cell and nuclear shapes, given shapes at a previous time point. We use this to determine the effects of endogenous protein tags or drugs on the shape dynamics of cell lines and show that tagged C1QBP reduces the correlation between cell and nuclear shape. To reduce the computational cost of learning these models, we demonstrate the ability to reconstruct shape spaces using a fraction of computed pairwise distances. The open-source tools provide a powerful basis for future studies of the molecular basis of cell organization. PMID:26354424

  10. Shape oscillations of elastic particles in shear flow.

    PubMed

    Subramaniam, Dhananjay Radhakrishnan; Gee, David J

    2016-09-01

    Particle suspensions are common to biological fluid flows; for example, flow of red- and white-blood cells, and platelets. In medical technology, current and proposed methods for drug delivery use membrane-bounded liquid capsules for transport via the microcirculation. In this paper, we consider a 3D linear elastic particle inserted into a Newtonian fluid and investigate the time-dependent deformation using a numerical simulation. Specifically, a boundary element technique is used to investigate the motion and deformation of initially spherical or spheroidal particles in bounded linear shear flow. The resulting deformed shapes reveal a steady-state profile that exhibits a 'tank-treading' motion for initially spherical particles. Wall effects on particle trajectory are seen to include a modified Jeffrey׳s orbit for spheroidal inclusions with a period that varies inversely with the strength of the shear flow. Alternately, spheroidal inclusions may exhibit either a 'tumbling' or 'trembling' motion depending on the initial particle aspect ratio and the capillary number (i.e., ratio of fluid shear to elastic restoring force). We find for a capillary number of 0.1, a tumbling mode transitions to a trembling mode at an aspect ratio of 0.87 (approx.), while for a capillary number of 0.2, this transition takes place at a lower aspect ratio. These oscillatory modes are consistent with experimental observations involving similarly shaped vesicles and thus serves to validate the use of a simple elastic constitutive model to perform relevant physiological flow calculations. PMID:27294284

  11. Development of Meter-Scale U-Shaped and O-Shaped Oscillating Heat Pipes for GAPS

    NASA Astrophysics Data System (ADS)

    Okazaki, Shun; Fuke, Hideyuki; Miyazaki, Yoshiro; Ogawa, Hiroyuki

    A meter-scale Oscillating Heat Pipe (OHP) has been developed for the General Anti-Particle Spectrometer (GAPS) project. Two types of OHP routing, U-shaped and O-shaped, have been investigated. For the operation at low temperature, R410A was used as the working fluid. As the result of the investigation, we verified for the first time that both the meter-scale U-shaped and O-shaped OHPs can transfer heat under gravity in a wide temperature range between 20°C and -60°C. Generally, the O-shaped OHP showed better performance than the U-shaped OHP. Both OHP models showed good thermal conductance and a good amount of heat transport under the particular sets of conditions which meet the design requirements. In order to clarify the drive force to operate OHP to further improve the OHP design, the performance difference between the U-shaped and the O-shaped models has been interpreted in terms of the gravity effect and the pressure loss.

  12. Self-organization of dynein motors generates meiotic nuclear oscillations.

    PubMed

    Vogel, Sven K; Pavin, Nenad; Maghelli, Nicola; Jülicher, Frank; Tolić-Nørrelykke, Iva M

    2009-04-21

    Meiotic nuclear oscillations in the fission yeast Schizosaccharomyces pombe are crucial for proper chromosome pairing and recombination. We report a mechanism of these oscillations on the basis of collective behavior of dynein motors linking the cell cortex and dynamic microtubules that extend from the spindle pole body in opposite directions. By combining quantitative live cell imaging and laser ablation with a theoretical description, we show that dynein dynamically redistributes in the cell in response to load forces, resulting in more dynein attached to the leading than to the trailing microtubules. The redistribution of motors introduces an asymmetry of motor forces pulling in opposite directions, leading to the generation of oscillations. Our work provides the first direct in vivo observation of self-organized dynamic dynein distributions, which, owing to the intrinsic motor properties, generate regular large-scale movements in the cell. PMID:19385717

  13. Study of extreme nuclear shapes in extreme conditions

    SciTech Connect

    Banerjee, Sudhee Ranjan

    2014-08-14

    Studies of extreme nuclear shapes have always fascinated scientists and are being pursued quite strongly over the years. Nuclei present themselves with interesting shapes and structures at different conditions of spin, excitation and also with the number of neutrons and/or protons in them. Gamma decays from the Giant dipole Resonances in nuclei can probe directly their shapes at different extreme conditions by looking at their resonant line-shapes, e.g., Jacobi shapes and shape-transitions, super/hyper-deformation etc. Similar such studies, done for the first time, using the LAMBDA high energy gamma spectrometer developed at VECC, is discussed here.

  14. Study of extreme nuclear shapes in extreme conditions

    NASA Astrophysics Data System (ADS)

    Banerjee, Sudhee Ranjan

    2014-08-01

    Studies of extreme nuclear shapes have always fascinated scientists and are being pursued quite strongly over the years. Nuclei present themselves with interesting shapes and structures at different conditions of spin, excitation and also with the number of neutrons and/or protons in them. Gamma decays from the Giant dipole Resonances in nuclei can probe directly their shapes at different extreme conditions by looking at their resonant line-shapes, e.g., Jacobi shapes and shape-transitions, super/hyper-deformation etc. Similar such studies, done for the first time, using the LAMBDA high energy gamma spectrometer developed at VECC, is discussed here.

  15. Moving Cell Boundaries Drive Nuclear Shaping during Cell Spreading

    PubMed Central

    Li, Yuan; Lovett, David; Zhang, Qiao; Neelam, Srujana; Kuchibhotla, Ram Anirudh; Zhu, Ruijun; Gundersen, Gregg G.; Lele, Tanmay P.; Dickinson, Richard B.

    2015-01-01

    The nucleus has a smooth, regular appearance in normal cells, and its shape is greatly altered in human pathologies. Yet, how the cell establishes nuclear shape is not well understood. We imaged the dynamics of nuclear shaping in NIH3T3 fibroblasts. Nuclei translated toward the substratum and began flattening during the early stages of cell spreading. Initially, nuclear height and width correlated with the degree of cell spreading, but over time, reached steady-state values even as the cell continued to spread. Actomyosin activity, actomyosin bundles, microtubules, and intermediate filaments, as well as the LINC complex, were all dispensable for nuclear flattening as long as the cell could spread. Inhibition of actin polymerization as well as myosin light chain kinase with the drug ML7 limited both the initial spreading of cells and flattening of nuclei, and for well-spread cells, inhibition of myosin-II ATPase with the drug blebbistatin decreased cell spreading with associated nuclear rounding. Together, these results show that cell spreading is necessary and sufficient to drive nuclear flattening under a wide range of conditions, including in the presence or absence of myosin activity. To explain this observation, we propose a computational model for nuclear and cell mechanics that shows how frictional transmission of stress from the moving cell boundaries to the nuclear surface shapes the nucleus during early cell spreading. Our results point to a surprisingly simple mechanical system in cells for establishing nuclear shapes. PMID:26287620

  16. Shape oscillations: A walk through the phase diagram of strained islands

    SciTech Connect

    Stoffel, M.; Rastelli, A.; Merdzhanova, T.; Stangl, J.; Bauer, G.; Schmidt, O. G.

    2007-03-15

    We observe that the morphology of strained SiGe/Si(001) islands oscillates between shallow and steeper shapes during extensive in situ annealing at the growth temperature. We attribute this result to a competition between coarsening and Si-Ge intermixing as paths to strain relaxation. A simple model, in which the equilibrium island shape depends on volume and the average misfit with the substrate, accounts for the observed behavior. Dislocated islands evolve similarly to coherent islands, with no introduction of additional dislocations throughout the annealing.

  17. Electrically induced shape oscillation of drops as a means of direct-contact heat transfer enhancement: Part 1 - Drop dynamics

    SciTech Connect

    Kaji, N. ); Mori, Y.H. ); Tochitani, Y. )

    1988-08-01

    The shape oscillation of liquid drops passing through an immiscible liquid medium subject to a low-frequency (1 {approximately} 16 Hz) alternating electric field having a sinusoidal waveform has been studied experimentally with the intention of investigating the enhancement of the direct-contact heat exahange between the two liquids. The authors have found that the field can induce, depending on its frequency, not only the resonant oscillation of the second mode of the drops, but also another peculiar oscillation that is related to the resonant oscillation of the third mode superposed on the second-mode oscillation.

  18. Study of nuclear shapes in extreme conditions

    NASA Astrophysics Data System (ADS)

    Muralithar, S.; Gamma spectroscopy Group in IUAC

    2013-04-01

    Studies of nuclear structure have fascinated physicists and was pursued for decades actively. Nuclear structure evolves as a function of proton and neutron ratio, energy and spin pumped into system. To facilitate nuclear structure study at high spin, a host of facilities were developed at Inter University Accelerator Centre, New Delhi and was used by users across this country for last twenty years. The tools developed, from Gamma detector array (GDA) with ancillary devices, to Indian National Gamma array (INGA) are presented with few physics cases.

  19. Exact Analytic Study of Nuclear Shape Phase Transitions

    SciTech Connect

    Levai, G.

    2009-08-26

    The application of the sextic oscillator is proposed in the Bohr Hamiltonian to describe the phase transition between the spherical and gamma-unstable shape phases. It is shown that exact results can be obtained for the energy eigenvalues and wave functions of the low-lying levels, as well as for electric quadrupole transition rates between them. The {sup 134}Ba nucleus and the even Ru isotope chain are considered as examples. Possible generalizations of the model are also outlined.

  20. Nuclear weak interactions, supernova nucleosynthesis and neutrino oscillation

    NASA Astrophysics Data System (ADS)

    Kajino, Toshitaka

    2013-07-01

    We study the nuclear weak response in light-to-heavy mass nuclei and calculate neutrino-nucleus cross sections. We apply these cross sections to the explosive nucleosynthesis in core-collapse supernovae and find that several isotopes of rare elements 7Li, 11B, 138La, 180Ta and several others are predominantly produced by the neutrino-process nucleosynthesis. We discuss how to determine the suitable neutrino spectra of three different flavors and their anti-particles in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. Light-mass nuclei like 7Li and 11B, which are produced in outer He-layer, are strongly affected by the neutrino flavor oscillation due to the MSW (Mikheyev-Smirnov-Wolfenstein) effect, while heavy-mass nuclei like 138La, 180Ta and r-process elements, which are produced in the inner O-Ne-Mg layer or the atmosphere of proto-neutron star, are likely to be free from the MSW effect. Using such a different nature of the neutrino-process nucleosynthesis, we study the neutrino oscillation effects on their abundances, and propose a new novel method to determine the unknown neutrino oscillation parameters, θ13 and mass hierarchy, simultaneously. There is recent evidence that some SiC X grains from the Murchison meteorite may contain supernova-produced neutrino-process 11B and 7Li encapsulated in the grains. Combining the recent experimental constraints on θ13, we show that although the uncertainties are still large, our method hints at a marginal preference for an inverted neutrino mass hierarchy for the first time.

  1. Spin-orbit interaction for the double ring-shaped oscillator

    NASA Astrophysics Data System (ADS)

    Chen, Chang-Yuan; Lu, Fa-Lin; Sun, Dong-Sheng; You, Yuan; Dong, Shi-Hai

    2016-08-01

    The spin-orbit interactions (SOI) for the single and double ring-shaped oscillator potentials are studied as an energy correction to the Schrödinger equation. We find that the degeneracy for the energy levels with angular quantum number m = 0 keeps invariant in the case of the SOI. The degeneracy is still 2 for single ring-shaped potential and 4 for double ring-shaped potential. However, for the energy levels with angular quantum number m ≠ 0 the degeneracy is reduced from original 4 for the single ring-shaped potential and 8 for the double ring-shaped potential to 2. That is, their energy levels in the case of the SOI are split to 2 (single) and 4 (double) sublevels. There exists an accidental degeneracy for the cases | m | = 2 , 3 , 4 , …. We note that around the critical value b0, the energy levels are reversed. We also discuss some special cases for η = 2 , 3 , 4 , 5 , 6 , …, and the b = 0 , c > 0. It should be pointed out that the parameter b0 is relevant for the angular part parameter b in the single and double ring-shaped potentials and it makes the energy levels changed from positive to negative, but the parameter c corresponds to the angular part parameter in double ring-shaped potential and the η is related to it. This model can be useful for investigations of axial symmetric subjects like the ring-shaped molecules or related problems and may also be easily extended to a many-electron theory.

  2. Nuclear hyperdeformation and the Jacobi shape transition

    SciTech Connect

    Schunck, N.; Dudek, J.

    2007-05-15

    The possibility that atomic nuclei possess stable, extremely elongated (hyperdeformed) shapes at very high angular momentum is investigated in the light of the most recent experimental results. The crucial role of the Jacobi shape transitions for the population of hyperdeformed states is discussed and emphasized. State-of-the-art mean-field calculations including the most recent parametrization of the liquid-drop energy together with thermal effects and minimization algorithms allowing the spanning of a large deformation space predict the existence of a region of hyperdeformed nuclei in the mass A{approx}120-130: Te, Cs, Xe, I, and Ba isotopes. In agreement with predictions presented in reviews by J. Dudek, K. Pomorski, N. Schunck, and N. Dubray [Eur. Phys. J. A 20, 15 (2003)] and J. Dudek, N. Schunck, and N. Dubray [Acta Phys Pol. B 36, 975 (2005)], our extended calculations predict that only very short hyperdeformed bands composed of a dozen discrete transitions at the most are to be expected-in contrast to the results known for the superdeformed bands. We stress the importance of the experimental research in terms of multiple-{gamma} correlation analysis that proved to be very efficient for the superdeformation studies and seems very helpful in the even more difficult search for the discrete transitions in hyperdeformed nuclei.

  3. High-power, femtosecond, thermal-lens-shaped Yb:KGW oscillator.

    PubMed

    Berger, Joel A; Greco, Michael J; Schroeder, W Andreas

    2008-06-01

    Thermal lens shaping for astigmatism compensation is extended to a high-power, diode-pumped, Yb:KGW laser by employing a gain crystal geometry designed for efficient polarized pumping. The 63MHz oscillator is soliton mode-locked with the aid of a saturable Bragg reflector to yield 250fs (347fs) pulses at an output power of 3.5W (5W). Frequency doubling of the 250fs pulses with an intrinsic efficiency >60% provides 1.65W of average green power. PMID:18545576

  4. Particle shape effect on heat transfer performance in an oscillating heat pipe

    PubMed Central

    2011-01-01

    The effect of alumina nanoparticles on the heat transfer performance of an oscillating heat pipe (OHP) was investigated experimentally. A binary mixture of ethylene glycol (EG) and deionized water (50/50 by volume) was used as the base fluid for the OHP. Four types of nanoparticles with shapes of platelet, blade, cylinder, and brick were studied, respectively. Experimental results show that the alumina nanoparticles added in the OHP significantly affect the heat transfer performance and it depends on the particle shape and volume fraction. When the OHP was charged with EG and cylinder-like alumina nanoparticles, the OHP can achieve the best heat transfer performance among four types of particles investigated herein. In addition, even though previous research found that these alumina nanofluids were not beneficial in laminar or turbulent flow mode, they can enhance the heat transfer performance of an OHP. PMID:21711830

  5. Mitigation of residual oscillations in electrostatically actuated microbeams using a command-shaping approach

    NASA Astrophysics Data System (ADS)

    Godara, R. K.; Joglekar, M. M.

    2015-11-01

    When electrostatically actuated microbeams are driven by an input-waveform comprising multiple voltage steps, the resulting response inherently contains residual oscillations, which may prove detrimental to the device performance and accuracy. In this article, we report the systematic development of a command shaping technique for mitigating such residual oscillations in electrostatically actuated microbeams and achieving fast switching between the successive equilibrium states. Invoking the force balance at a critical point in an oscillation cycle, the proposed technique relies on bringing the actuator to a stagnation state by applying an additional voltage signal of specific amplitude at a predetermined time. The underlying principle of the technique is enunciated for the lumped parallel-plates model of the microactuator, and further extended to the cases of microbeams. The electromechanical model of the microbeam incorporates the effects of full-order electrostatic nonlinearity, moderately large deflections, viscous energy dissipation, and fringing fields. The modal superposition method is employed to obtain the dynamic response of microbeams. Based on a single-mode assumption, the proposed technique lends itself to a simple multistep waveform, which is attractive from the implementation point of view. The applicability of the proposed technique is demonstrated by considering a wide range of parameters involving variations in the extent of geometric nonlinearity, damping, and equilibrium sequences. The impact of higher modes on the stabilized response is exposited, and a command shaping approach based on the multi-mode response of the actuator is suggested. In particular, such an approach is shown to be effective in controlling the motion of the beam in the vicinity of the static pull-in displacement, which is associated with strong electrostatic nonlinearity. The present investigation can find its potential use in the development of an open-loop controller for

  6. Regulation of nuclear shape and size in plants.

    PubMed

    Meier, Iris; Griffis, Anna Hn; Groves, Norman R; Wagner, Alecia

    2016-06-01

    Nuclear shape and size changes have long been used by cytopathologists to diagnose, stage, and prognose cancer. However, the underlying causalities and molecular mechanisms are largely unknown. The current eukaryotic tree of life groups eukaryotes into five supergroups, with all organisms between humans and yeast falling into the supergroup Opisthokonta. The emergence of model organisms with strong molecular genetic methodology in the other supergroups has recently facilitated a broader evolutionary approach to pressing biological questions. Here, we review what is known about the control of nuclear shape and size in the Archaeplastidae, the supergroup containing the higher plants. We discuss common themes as well as differences toward a more generalized model of how eukaryotic organisms regulate nuclear morphology. PMID:27030912

  7. Self-oscillating Gel Accelerated while Sensing the Shape of an Aqueous Surface.

    PubMed

    Yoshii, Miyu; Yamamoto, Hiroya; Sumino, Yutaka; Nakata, Satoshi

    2016-04-26

    The reciprocating motion of a self-oscillating square gel induced by the Belousov-Zhabotinsky (BZ) reaction was investigated on an aqueous surface. The chemical wave propagated from the side at which the oxidation of the Ru catalyst in the gel started. As the chemical wave propagated, the gel moved in either the opposite (mode I) or the same (mode II) direction as the chemical wave propagation. The gel then went back as the Ru catalyst in the gel was slowly reduced. We examined the relationship between the modes of motion (mode I or II) and the shape of the aqueous BZ solution surface. The mode selection was discussed in relation to the contact angle around the gel which was changed by the BZ reaction, i.e., the lateral imbalance of surface tension and the capillary interaction. PMID:27030999

  8. GENERAL: Solving Dirac Equation with New Ring-Shaped Non-Spherical Harmonic Oscillator Potential

    NASA Astrophysics Data System (ADS)

    Hu, Xian-Quan; Luo, Guang; Wu, Zhi-Min; Niu, Lian-Bin; Ma, Yan

    2010-02-01

    A new ring-shaped non-harmonic oscillator potential is proposed. The precise hound solution of Dirac equation with the potential is gained when the scalar potential is equal to the vector potential. The angular equation and radial equation are obtained through the variable separation method. The results indicate that the normalized angle wave function can be expressed with the generalized associated-Legendre polynomial, and the normalized radial wave function can be expressed with confluent hypergeometric function. And then the precise energy spectrum equations are obtained. The ground state and several low excited states of the system are solved. And those results are compared with the non-relativistic effect energy level in Phys. Lett. A 340 (2005) 94. The positive energy states of system are discussed and the conclusions are made properly.

  9. Model for the dynamics of two interacting axisymmetric spherical bubbles undergoing small shape oscillations.

    PubMed

    Kurihara, Eru; Hay, Todd A; Ilinskii, Yurii A; Zabolotskaya, Evgenia A; Hamilton, Mark F

    2011-11-01

    Interaction between acoustically driven or laser-generated bubbles causes the bubble surfaces to deform. Dynamical equations describing the motion of two translating, nominally spherical bubbles undergoing small shape oscillations in a viscous liquid are derived using Lagrangian mechanics. Deformation of the bubble surfaces is taken into account by including quadrupole and octupole perturbations in the spherical-harmonic expansion of the boundary conditions on the bubbles. Quadratic terms in the quadrupole and octupole amplitudes are retained, and surface tension and shear viscosity are included in a consistent manner. A set of eight coupled second-order ordinary differential equations is obtained. Simulation results, obtained by numerical integration of the model equations, exhibit qualitative agreement with experimental observations by predicting the formation of liquid jets. Simulations also suggest that bubble-bubble interactions act to enhance surface mode instability. PMID:22088009

  10. Maximum in the damping of shape oscillations of foam drops near the critical void fraction

    NASA Astrophysics Data System (ADS)

    Wang, Hai; Liu, Li; McDaniel, Gregory J.; Holt, Glynn R.

    2001-05-01

    Small spheroidal samples of aqueous foam (``foam drops'') of varying gas volume fraction are acoustically levitated in an ultrasonic field. The normalized natural frequency and damping ratio are determined by treating a foam drop as a damped linear oscillator and measuring shape mode frequency response. The observed natural frequencies are compared to a wet foam model without any fitting parameters. Good agreement is found for gas volume fractions ranging from 0.01 to 0.87. The observed damping ratio of a foam drop exhibits a maximum for gas volume fractions 0.5 to 0.7. The data are inverted to infer the shear elastic modulus and its dependence on gas volume fraction for dry foams. [Work supported by NASA.

  11. Surface characterization through shape oscillations of drops in microgravity and 1-g

    NASA Technical Reports Server (NTRS)

    Apfel, Robert E.; Holt, R. Glynn; Tian, Yuren; Shi, Tao; Zheng, Xiao-Yu

    1994-01-01

    The goal of these experiments is to determine the rheological properties of liquid drops of single or multiple components in the presence or absence of surface active materials by exciting drops into their quadrupole resonance and observing their free decay. The resulting data coupled with appropriate theory should give a better description of the physics of the underlying phenomena, providing a better foundation than earlier empirical results could. The space environment makes an idealized geometry available (spherical drops) so that theory and experiment can be properly compared, and allows a 'clean' environment, by which is meant an environment in which no solid surfaces come in contact with the drops during the test period. Moreover, by considering the oscillations of intentionally deformed drops in microgravity, a baseline is established for interpreting surface characterization experiments done on the ground by other groups and ours. Experiments performed on the United States Microgravity Laboratory Laboratory (USML-1) demonstrated that shape oscillation experiments could be performed over a wide parameter range, and with a variety of surfactant materials. Results, however, were compromised by an unexpected, slow drop tumbling, some problems with droplet injection, and the presence of bubbles in the drop samples. Nevertheless, initial data suggests that the space environment will be useful in providing baseline data that can serve to validate theory and permit quantitative materials characterization at 1-g.

  12. Cytoskeletal prestress regulates nuclear shape and stiffness in cardiac myocytes.

    PubMed

    Lee, Hyungsuk; Adams, William J; Alford, Patrick W; McCain, Megan L; Feinberg, Adam W; Sheehy, Sean P; Goss, Josue A; Parker, Kevin Kit

    2015-11-01

    Mechanical stresses on the myocyte nucleus have been associated with several diseases and potentially transduce mechanical stimuli into cellular responses. Although a number of physical links between the nuclear envelope and cytoplasmic filaments have been identified, previous studies have focused on the mechanical properties of individual components of the nucleus, such as the nuclear envelope and lamin network. The mechanical interaction between the cytoskeleton and chromatin on nuclear deformability remains elusive. Here, we investigated how cytoskeletal and chromatin structures influence nuclear mechanics in cardiac myocytes. Rapid decondensation of chromatin and rupture of the nuclear membrane caused a sudden expansion of DNA, a consequence of prestress exerted on the nucleus. To characterize the prestress exerted on the nucleus, we measured the shape and the stiffness of isolated nuclei and nuclei in living myocytes during disruption of cytoskeletal, myofibrillar, and chromatin structure. We found that the nucleus in myocytes is subject to both tensional and compressional prestress and its deformability is determined by a balance of those opposing forces. By developing a computational model of the prestressed nucleus, we showed that cytoskeletal and chromatin prestresses create vulnerability in the nuclear envelope. Our studies suggest the cytoskeletal-nuclear-chromatin interconnectivity may play an important role in mechanics of myocyte contraction and in the development of laminopathies by lamin mutations. PMID:25908635

  13. Search for an Atomic EDM with Optical-Coupling Nuclear Spin Oscillator

    SciTech Connect

    Asahi, K.; Uchida, M.; Inoue, T.; Hatakeyama, N.; Yoshimi, A.

    2007-06-13

    We have constructed a nuclear spin oscillator of a new type, that employs a feedback scheme based on an optical spin detection and suceeding spin control by a transverse field application. This spin oscillator parallels the conventional spin maser in many points, but exhibits advantages and requirements that are different from those with the spin maser. By means of the optical-coupling nuclear spin oscillator, an experimental setup to search for an electric dipole moment (EDM) in a spin 1/2 diamagnetic atom 129Xe is being developed.

  14. Nuclear-localized cyclic nucleotide-gated channels mediate symbiotic calcium oscillations.

    PubMed

    Charpentier, Myriam; Sun, Jongho; Vaz Martins, Teresa; Radhakrishnan, Guru V; Findlay, Kim; Soumpourou, Eleni; Thouin, Julien; Véry, Anne-Aliénor; Sanders, Dale; Morris, Richard J; Oldroyd, Giles E D

    2016-05-27

    Nuclear-associated Ca(2+) oscillations mediate plant responses to beneficial microbial partners--namely, nitrogen-fixing rhizobial bacteria that colonize roots of legumes and arbuscular mycorrhizal fungi that colonize roots of the majority of plant species. A potassium-permeable channel is known to be required for symbiotic Ca(2+) oscillations, but the calcium channels themselves have been unknown until now. We show that three cyclic nucleotide-gated channels in Medicago truncatula are required for nuclear Ca(2+) oscillations and subsequent symbiotic responses. These cyclic nucleotide-gated channels are located at the nuclear envelope and are permeable to Ca(2+) We demonstrate that the cyclic nucleotide-gated channels form a complex with the postassium-permeable channel, which modulates nuclear Ca(2+) release. These channels, like their counterparts in animal cells, might regulate multiple nuclear Ca(2+) responses to developmental and environmental conditions. PMID:27230377

  15. The Effect of Shape Mode Oscillations on the Particle Scavenging Efficiency of Water Droplets Using Acoustic Levitation

    NASA Astrophysics Data System (ADS)

    Kizzee, J.; Saylor, J. R.

    2010-11-01

    The effect of drop oscillations on the scavenging of solid particles is studied using an ultrasonic transducer to levitate a water droplet in an airflow of particles. Shape mode oscillations are induced in the drop by modulating the acoustic field used for levitation. The effect of oscillation frequency, the oscillation amplitude, and the drop diameter on the scavenging of particles is presented. The particle diameters are on the order of 1μm and the drop diameters are on the order of 1mm. Although single droplets are studied here, the application of interest is improved scavenging of particles by spray drops. Specifically, improving the elimination of coal dust particles from mines using waters sprays excited ultrasonically is of interest.

  16. Cytoskeletal prestress regulates nuclear shape and stiffness in cardiac myocytes

    PubMed Central

    Lee, Hyungsuk; Adams, William J; Alford, Patrick W; McCain, Megan L; Feinberg, Adam W; Sheeny, Sean P; Goss, Josue A

    2015-01-01

    Mechanical stresses on the myocyte nucleus have been associated with several diseases and potentially transduce mechanical stimuli into cellular responses. Although a number of physical links between the nuclear envelope and cytoplasmic filaments have been identified, previous studies have focused on the mechanical properties of individual components of the nucleus, such as the nuclear envelope and lamin network. The mechanical interaction between the cytoskeleton and chromatin on nuclear deformability remains elusive. Here, we investigated how cytoskeletal and chromatin structures influence nuclear mechanics in cardiac myocytes. Rapid decondensation of chromatin and rupture of the nuclear membrane caused a sudden expansion of DNA, a consequence of prestress exerted on the nucleus. To characterize the prestress exerted on the nucleus, we measured the shape and the stiffness of isolated nuclei and nuclei in living myocytes during disruption of cytoskeletal, myofibrillar, and chromatin structure. We found that the nucleus in myocytes is subject to both tensional and compressional prestress and its deformability is determined by a balance of those opposing forces. By developing a computational model of the prestressed nucleus, we showed that cytoskeletal and chromatin prestresses create vulnerability in the nuclear envelope. Our studies suggest the cytoskeletal–nuclear–chromatin interconnectivity may play an important role in mechanics of myocyte contraction and in the development of laminopathies by lamin mutations. PMID:25908635

  17. Ryanodine receptors are involved in nuclear calcium oscillation in primary pancreatic {beta}-cells

    SciTech Connect

    Zheng, Ji; Chen, Zheng; Yin, Wenxuan; Miao, Lin; Zhou, Zhansong; Ji, Guangju

    2012-06-29

    Highlights: Black-Right-Pointing-Pointer We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Black-Right-Pointing-Pointer We showed that the pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. Black-Right-Pointing-Pointer Our results demonstrate that ryanodine-sensitive Ca{sup 2+} stores exist and have function in the pancreatic {beta}-cell nucleus. -- Abstract: Ryanodine receptors (RyRs) are mainly located on the endoplasmic reticulum (ER) and play an important role in regulating glucose-induced cytosolic Ca{sup 2+} oscillation in pancreatic {beta}-cells. However, subcellular locations and functions of RyRs on other cell organelles such as nuclear envelope are not well understood. In order to investigate the role of RyRs in nuclear Ca{sup 2+} oscillation we designed and conducted experiments in intact primary pancreatic {beta}-cells. Immunocytochemistry was used to examine the expression of RYRs on the nuclear envelope. Confocal microscopy was used to evaluate the function of RYRs on the nuclear envelope. We found that RyRs are expressed on the nuclear envelope in single primary pancreatic {beta}-cells and isolated nuclei. Laser scanning confocal microscopy studies indicated that application of glucose to the cells co-incubated with Ca{sup 2+} indicator Fluo-4 AM and cell-permeable nuclear indicator Hoechst 33342 resulted in nuclear Ca{sup 2+} oscillation. The pattern of glucose-induced Ca{sup 2+} oscillation in the nucleus and cytosol was similar. The reduction of Ca{sup 2+} oscillation amplitude by ryanodine was much greater in the nucleus though both the cytosol and the nucleus Ca{sup 2+} amplitude decreased by ryanodine. Our results suggest that functional ryanodine receptors not only exist in endoplasmic reticulum but are also expressed in nuclear envelope of pancreatic {beta}-cells.

  18. Shape oscillations of acoustically levitated drops in water: Early research with Bob Apfel on modulated radiation pressure

    NASA Astrophysics Data System (ADS)

    Marston, Philip L.

    2001-05-01

    In 1976, research in collaboration with Bob Apfel demonstrated that low-frequency shape oscillations of hydrocarbon drops levitated in water could be driven using modulated radiation pressure. While that response to modulated ultrasound was subsequently extended to a range of systems, the emphasis here is to recall the initial stages of development in Bob Apfel's laboratory leading to some publications [P. L. Marston and R. E. Apfel, J. Colloid Interface Sci. 68, 280-286 (1979); J. Acoust. Soc. Am. 67, 27-37 (1980)]. The levitation technology used at that time was such that it was helpful to develop a sensitive method for detecting weak oscillations using the interference pattern in laser light scattered by levitated drops. The initial experiments to verify this scattering method used shape oscillations induced by modulated electric fields within the acoustic levitator. Light scattering was subsequently used to detect shape oscillations induced by amplitude modulating a carrier having a high frequency (around 680 kHz) at a resonance of the transducer. Methods were also developed for quantitative measurements of the drop's response and with improved acoustic coupling drop fission was observed. The connection with research currently supported by NASA will also be noted.

  19. Shape and topography corrections for planetary nuclear spectroscopy

    NASA Astrophysics Data System (ADS)

    Prettyman, Thomas H.; Hendricks, John S.

    2015-11-01

    The elemental composition of planetary surfaces can be determined using gamma ray and neutron spectroscopy. Most planetary bodies for which nuclear spectroscopy data have been acquired are round, and simple, analytic corrections for measurement geometry can be applied; however, recent measurements of the irregular asteroid 4 Vesta by Dawn required more detailed corrections using a shape model (Prettyman et al., Science 2012). In addition, subtle artifacts of topography have been observed in low altitude measurements of lunar craters, with potential implications for polar hydrogen content (Eke et al., JGR 2015). To explore shape and topography effects, we have updated the general-purpose Monte Carlo radiation transport code MCNPX to include a polygonal shape model (Prettyman and Hendricks, LPSC 2015). The shape model is fully integrated with the code’s 3D combinatorial geometry modules. A voxel-based acceleration algorithm enables fast ray-intersection calculations needed for Monte Carlo. As modified, MCNPX can model neutron and gamma ray transport within natural surfaces using global and/or regional shape/topography data (e.g. from photogrammetry and laser altimetry). We are using MCNPX to explore the effect of small-scale roughness, regional-, and global-topography for asteroids, comets and close-up measurements of high-relief features on larger bodies, such as the lunar surface. MCNPX can characterize basic effects on measurements by an orbiting spectrometer such as 1) the angular distribution of emitted particles, 2) shielding of galactic cosmic rays by surrounding terrain and 3) re-entrant scattering. In some cases, re-entrant scattering can be ignored, leading to a fast ray-tracing model that treats effects 1 and 2. The algorithm is applied to forward modeling and spatial deconvolution of epithermal neutron data acquired at Vesta. Analyses of shape/topography effects and correction strategies are presented for Vesta, selected small bodies and cratered

  20. Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

    NASA Astrophysics Data System (ADS)

    Nichol, John M.; Hemesath, Eric R.; Lauhon, Lincoln J.; Budakian, Raffi

    2012-02-01

    The authors report the use of a radio frequency (rf) silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1H spins in polystyrene. To couple the 1H spins to the nanowire oscillator, a magnetic resonance force detection protocol was developed that utilizes a nanoscale current-carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited an ultralow force noise near the thermal limit of the oscillator.

  1. A 22-watt mid-infrared optical parametric oscillator with V-shaped 3-mirror ring resonator.

    PubMed

    Lippert, Espen; Fonnum, Helge; Arisholm, Gunnar; Stenersen, Knut

    2010-12-01

    We report on a ZnGeP(2)-based optical parametric oscillator (OPO) with 22 W of output power in the 3-5 µm range and a beam quality factor M(2) ≈1.4. The OPO uses a novel V-shaped 3-mirror ring resonator that allows two passes of the beams through the same nonlinear crystal. The pump is a 39 W hybrid Tm:fiber laser/Ho:YAG laser. PMID:21164998

  2. Impact of nuclear effects on the extraction of neutrino oscillation parameters.

    PubMed

    Coloma, P; Huber, P

    2013-11-27

    study the possible impact of nuclear effects and final state interactions on the determination of the oscillation parameters due to the misreconstruction of nonquasielastic events as quasielastic events at low energies. We analyze a ν(μ) disappearance experiment using a water Čerenkov detector. We find that, if completely ignored in the fit, nuclear effects can induce a significant bias in the determination of atmospheric oscillation parameters, particularly for the atmospheric mixing angle. Even after inclusion of a near detector, a bias in the determination of the atmospheric mixing angle comparable to the statistical error remains. PMID:24329438

  3. M-shaped asymmetric nonlinear oscillator for broadband vibration energy harvesting: Harmonic balance analysis and experimental validation

    NASA Astrophysics Data System (ADS)

    Leadenham, S.; Erturk, A.

    2014-11-01

    Over the past few years, nonlinear oscillators have been given growing attention due to their ability to enhance the performance of energy harvesting devices by increasing the frequency bandwidth. Duffing oscillators are a type of nonlinear oscillator characterized by a symmetric hardening or softening cubic restoring force. In order to realize the cubic nonlinearity in a cantilever at reasonable excitation levels, often an external magnetic field or mechanical load is imposed, since the inherent geometric nonlinearity would otherwise require impractically high excitation levels to be pronounced. As an alternative to magnetoelastic structures and other complex forms of symmetric Duffing oscillators, an M-shaped nonlinear bent beam with clamped end conditions is presented and investigated for bandwidth enhancement under base excitation. The proposed M-shaped oscillator made of spring steel is very easy to fabricate as it does not require extra discrete components to assemble, and furthermore, its asymmetric nonlinear behavior can be pronounced yielding broadband behavior under low excitation levels. For a prototype configuration, linear and nonlinear system parameters extracted from experiments are used to develop a lumped-parameter mathematical model. Quadratic damping is included in the model to account for nonlinear dissipative effects. A multi-term harmonic balance solution is obtained to study the effects of higher harmonics and a constant term. A single-term closed-form frequency response equation is also extracted and compared with the multi-term harmonic balance solution. It is observed that the single-term solution overestimates the frequency of upper saddle-node bifurcation point and underestimates the response magnitude in the large response branch. Multi-term solutions can be as accurate as time-domain solutions, with the advantage of significantly reduced computation time. Overall, substantial bandwidth enhancement with increasing base excitation is

  4. Oscillations of Bubble Shape Cause Anomalous Surfactant Diffusion: Experiments, Theory, and Simulations.

    PubMed

    Raudino, Antonio; Raciti, Domenica; Grassi, Antonio; Pannuzzo, Martina; Corti, Mario

    2016-08-30

    We investigate, both theoretically and experimentally, the role played by the oscillations of the cell membrane on the capture rate of substances freely diffusing around the cell. To obtain quantitative results, we propose and build up a reproducible and tunable biomimetic experimental model system to simulate the phenomenon of an oscillation-enhanced (or depressed) capture rate (chemoreception) of a diffusant. The main advantage compared to real biological systems is that the different oscillation parameters (type of deformation, frequencies, and amplitudes) can be finely tuned. The model system that we use is an anchored gas drop submitted to a diffusive flow of charged surfactants. When the surfactant meets the surface of the bubble, it is reversibly adsorbed. Bubble oscillations of the order of a few nanometers are selectively excited, and surfactant transport is accurately measured. The surfactant concentration past the oscillating bubbles was detected by conductivity measurements. The results highlight the role of surface oscillations on the diffusant capture rate. Particularly unexpected is the onset of intense overshoots during the adsorption process. The phenomenon is particularly relevant when the bubbles are exposed to intense forced oscillations near resonance. PMID:27509197

  5. Role of nuclear physics in oscillations of magnetars

    NASA Astrophysics Data System (ADS)

    Nandi, Rana; Char, Prasanta; Chatterjee, Debarati; Bandyopadhyay, Debades

    2016-08-01

    Strong magnetic fields have important effects on the crustal properties of magnetars. Here we study the magnetoelastic oscillations of magnetars, taking into consideration the effect of strong magnetic fields on the crustal composition (magnetized crust). We calculate global magnetoelastic (GME) modes as well as modes confined to the crust (CME) only. The ideal magnetohydrodynamics is adopted for the calculation of magnetoelastic oscillations of magnetars with dipole magnetic fields. The perturbation equations obtained in general relativity using Cowling approximation are exploited here for the study of magnetoelastic oscillations. Furthermore, deformations due to magnetic fields and rotations are neglected in the construction of equilibrium models for magnetars. The composition of the crust directly affects its shear modulus, which we calculate using three different nucleon-nucleon interactions: SLy4, SkM, and Sk272. The shear modulus of the crust is found to be enhanced in strong magnetic fields ≥1017 G for all those Skyrme interactions. It is noted that the shear modulus of the crust for the SLy4 interaction is much higher than those of the SkM and Sk272 interactions in presence of magnetic fields or not. Though we do not find any appreciable change in frequencies of fundamental GME and CME modes with and without magnetized crusts, frequencies of first overtones of CME modes are significantly affected in strong magnetic fields ≥1017 G. However, this feature is not observed in frequencies of first overtones of GME modes. As in earlier studies, it is also noted that the effects of crusts on frequencies of both types of magnetoelastic modes disappear when the magnetic field reaches the critical field (B >4 ×1015 G). Frequencies of GME and CME modes calculated with magnetized crusts based on all three nucleon-nucleon interactions, stellar models and magnetic fields, are compared with frequencies of observed quasiperiodic oscillations (QPOs) in SGR 1806-20 and

  6. Burst Oscillation Probes of Neutron Stars and Nuclear Burning with LOFT

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2012-01-01

    X-ray brightness oscillations during thermonuclear X-ray bursts--burst oscillations--have provided a new probe of neutron star spins as well as of the dependent nuclear burning processes. The frequency drift and amplitude evolution of the oscillations observed during bursts can in principle place constraints on the physics of thermonuclear flame spreading and the dynamics of the burning atmosphere. I use simulations appropriate to LOFT to explore the precision with which the time dependence of the oscillation frequency can be inferred. This can test, for example, different models for the frequency drift, such as up-lift versus geostrophic drift. I also explore the precision with which asymptotic frequencies can be constrained in order to estimate the capability for LOFT to detect the Doppler shifts induced by orbital motion of the neutron star from a sample of bursts at different orbital phases.

  7. Shape Oscillations of Bubbles in Water Driven by Modulated Ultrasonic Radiation Pressure and Applications to Interfacial Dynamics

    NASA Astrophysics Data System (ADS)

    Asaki, Thomas James

    1995-01-01

    Acoustic levitation techniques were used for static and dynamic studies of single air bubbles in aqueous solutions. Bubble sizes ranged from 0.3 to 6 mm in radius. The static position of a bubble, determined by the balance between the buoyant and acoustic forces, agrees well with existing theory. Measured bubble aspect ratios are a nonmonotonic increasing function of bubble size and agree well with an improved expression based on the radiation stress tensor. Small amplitude normal mode shape oscillations were induced by modulation of the acoustic radiation pressure and were detected by optical pseudo-extinction and optical interferometry techniques. Driven oscillation frequencies for bubbles in clean water agree well with Lamb theory although significant frequency shifts occur for bubbles of large aspect ratio (_sp{~ }{>}1.3). An improved asymptotic expansion, important for bubbles in fluids and for liquid drops in air, was obtained for the complex free decay frequency. The free decay of quadrupole shape oscillations was measured for nearly spherical bubbles (aspect ratio ~ 1.01) in clean water, clean salt water, sea water, and in the presence of surfactants. Bubbles in clean solutions exhibit behavior indicative of an ideal clean interface. Frequency shifts and excess damping were observed for bubbles in sea water, in aqueous solutions of Triton X-100, and for a bubble coated with the insoluble surfactant stearic acid. The damping and frequency exhibit nonmonotonic behavior with respect to interfacial surfactant coverage; maxima occur at coverages which do not significantly affect the surface tension. At large coverages the damping is increased and the frequency is reduced relative to theoretical expectations for a clean ideal interface at constant surface tension. These results are in qualitative agreement with theories incorporating interfacial viscoelastic effects and with planar-surface capillary ripple experiments which also exhibit maxima in the damping as a

  8. Irradiation-induced changes in nuclear shape and cell cycle

    SciTech Connect

    Iwata, M.; Sasaki, H.; Kishino, Y.; Tsuboi, T.; Sugishita, T.; Hosokawa, T.

    1982-03-01

    Using human uterine cervical carcinoma cells transplanted in nude mice and mice leukemia L5178Y cells, changes in the cell cycle following irradiation were observed by flow cytometry (FCM), and changes in the cell nuclei during the course of irradiation were measured by FCM. Experiments in vivo as well as in vitro caused accumulation of cells in the G2 to M populations, resulting in the so-called G2 block phenomenon as revealed by FCM analysis of DNA distributions. The radiation-induced changes of nuclear shapes were dependent on abnormal mitoses, which occurred more frequently in the G2 to M phases. Therefore it is suggested that the G2 block phenomenon plays an important role in radiation-induced cell death because the process of cell death by irradiation has been shown to proceed via these abnormal mitoses.

  9. Spin-exchange narrowing in a nuclear magnetic transverse oscillator

    NASA Astrophysics Data System (ADS)

    Korver, Anna; Thrasher, Daniel; Bulatowicz, Michael; Walker, Thad

    2015-05-01

    We demonstrate spin exchange narrowing in synchronously pumped Xe NMR. The Xe NMR is driven by spin exchange with Rb atoms whose polarization is square-wave modulated at the Xe NMR frequency. On resonance, the nuclei precess in phase with the Rb polarization. Off resonance, however, the spin-exchange fields from the Rb cause the Xe to develop a static orthogonal spin component. This induces broadening in the NMR line while also dramatically suppressing the phase shift between the precessing Rb and Xe polarizations. We can compensate for this effect by adding an oscillating magnetic field oriented along the optical pumping axis and 180 degrees out of phase with the Rb polarization. This narrows the NMR line width to approximately the T1 limit, and nearly restores the usual relationship between detuning and phase shift. These results suggest the possibility of using the alkali field with appropriate magnetic field feedback along the bias field direction to narrow the NMR linewidth below the usual T1 limit. Support by the NSF and Northrop Grumman Co.

  10. Laser-Driven Coherent Betatron Oscillation in a Laser-Wakefield Cavity: Formation of Sinusoid Beam Shapes and Coherent Trajectories

    SciTech Connect

    Nemeth, Karoly; Li Yuelin; Shang Hairong; Harkay, Katherine C.; Shen Baifei; Crowell, Robert; Cary, John R.

    2009-01-22

    High amplitude coherent electron-trajectories have been seen in 3D particle-in-cell simulations of the colliding pulse injection scheme of laser-wakefield accelerators in the bubble regime, and explained as a consequence of laser-driven coherent betatron oscillation in our recent paper [K. Nemeth et al., Phys. Rev. Lett. 100, 095002 (2008)]. In the present paper we provide more details on the shape of the trajectories, their relationship to the phase velocity of the laser and indicate the dependence of the phenomenon on the accuracy of the numerical representation and choice of laser/plasma parameters.

  11. Cell shape and the microenvironment regulate nuclear translocation of NF-κB in breast epithelial and tumor cells

    PubMed Central

    Sero, Julia E; Sailem, Heba Zuhair; Ardy, Rico Chandra; Almuttaqi, Hannah; Zhang, Tongli; Bakal, Chris

    2015-01-01

    Although a great deal is known about the signaling events that promote nuclear translocation of NF-κB, how cellular biophysics and the microenvironment might regulate the dynamics of this pathway is poorly understood. In this study, we used high-content image analysis and Bayesian network modeling to ask whether cell shape and context features influence NF-κB activation using the inherent variability present in unperturbed populations of breast tumor and non-tumor cell lines. Cell–cell contact, cell and nuclear area, and protrusiveness all contributed to variability in NF-κB localization in the absence and presence of TNFα. Higher levels of nuclear NF-κB were associated with mesenchymal-like versus epithelial-like morphologies, and RhoA-ROCK-myosin II signaling was critical for mediating shape-based differences in NF-κB localization and oscillations. Thus, mechanical factors such as cell shape and the microenvironment can influence NF-κB signaling and may in part explain how different phenotypic outcomes can arise from the same chemical cues. PMID:25735303

  12. Cell shape and the microenvironment regulate nuclear translocation of NF-κB in breast epithelial and tumor cells.

    PubMed

    Sero, Julia E; Sailem, Heba Zuhair; Ardy, Rico Chandra; Almuttaqi, Hannah; Zhang, Tongli; Bakal, Chris

    2015-01-01

    Although a great deal is known about the signaling events that promote nuclear translocation of NF-κB, how cellular biophysics and the microenvironment might regulate the dynamics of this pathway is poorly understood. In this study, we used high-content image analysis and Bayesian network modeling to ask whether cell shape and context features influence NF-κB activation using the inherent variability present in unperturbed populations of breast tumor and non-tumor cell lines. Cell-cell contact, cell and nuclear area, and protrusiveness all contributed to variability in NF-κB localization in the absence and presence of TNFα. Higher levels of nuclear NF-κB were associated with mesenchymal-like versus epithelial-like morphologies, and RhoA-ROCK-myosin II signaling was critical for mediating shape-based differences in NF-κB localization and oscillations. Thus, mechanical factors such as cell shape and the microenvironment can influence NF-κB signaling and may in part explain how different phenotypic outcomes can arise from the same chemical cues. PMID:25735303

  13. Cell shape and the microenvironment regulate nuclear translocation of NF-κB in breast epithelial and tumor cells.

    PubMed

    Sero, Julia E; Sailem, Heba Zuhair; Ardy, Rico Chandra; Almuttaqi, Hannah; Zhang, Tongli; Bakal, Chris

    2015-03-01

    Although a great deal is known about the signaling events that promote nuclear translocation of NF-κB, how cellular biophysics and the microenvironment might regulate the dynamics of this pathway is poorly understood. In this study, we used high-content image analysis and Bayesian network modeling to ask whether cell shape and context features influence NF-κB activation using the inherent variability present in unperturbed populations of breast tumor and non-tumor cell lines. Cell–cell contact, cell and nuclear area, and protrusiveness all contributed to variability in NF-κB localization in the absence and presence of TNFα. Higher levels of nuclear NF-κB were associated with mesenchymal-like versus epithelial-like morphologies, and RhoA-ROCK-myosin II signaling was critical for mediating shape-based differences in NF-κB localization and oscillations. Thus, mechanical factors such as cell shape and the microenvironment can influence NF-κB signaling and may in part explain how different phenotypic outcomes can arise from the same chemical cues. PMID:26148352

  14. Coexistence of nuclear shapes: self-consistent mean-field and beyond

    NASA Astrophysics Data System (ADS)

    Li, Z. P.; Nikšić, T.; Vretenar, D.

    2016-02-01

    A quantitative analysis of the evolution of nuclear shapes and shape phase transitions, including regions of short-lived nuclei that are becoming accessible in experiments at radioactive-beam facilities, necessitate accurate modeling of the underlying nucleonic dynamics. Important theoretical advances have recently been made in studies of complex shapes and the corresponding excitation spectra and electromagnetic decay patterns, especially in the ‘beyond mean-field’ framework based on nuclear density functionals. Interesting applications include studies of shape evolution and coexistence in N = 28 isotones, the structure of lowest 0+ excitations in deformed N ≈ 90 rare-earth nuclei, and quadrupole and octupole shape transitions in thorium isotopes.

  15. Input-Dependent Frequency Modulation of Cortical Gamma Oscillations Shapes Spatial Synchronization and Enables Phase Coding

    PubMed Central

    Lowet, Eric; Roberts, Mark; Hadjipapas, Avgis; Peter, Alina; van der Eerden, Jan; De Weerd, Peter

    2015-01-01

    Fine-scale temporal organization of cortical activity in the gamma range (∼25–80Hz) may play a significant role in information processing, for example by neural grouping (‘binding’) and phase coding. Recent experimental studies have shown that the precise frequency of gamma oscillations varies with input drive (e.g. visual contrast) and that it can differ among nearby cortical locations. This has challenged theories assuming widespread gamma synchronization at a fixed common frequency. In the present study, we investigated which principles govern gamma synchronization in the presence of input-dependent frequency modulations and whether they are detrimental for meaningful input-dependent gamma-mediated temporal organization. To this aim, we constructed a biophysically realistic excitatory-inhibitory network able to express different oscillation frequencies at nearby spatial locations. Similarly to cortical networks, the model was topographically organized with spatially local connectivity and spatially-varying input drive. We analyzed gamma synchronization with respect to phase-locking, phase-relations and frequency differences, and quantified the stimulus-related information represented by gamma phase and frequency. By stepwise simplification of our models, we found that the gamma-mediated temporal organization could be reduced to basic synchronization principles of weakly coupled oscillators, where input drive determines the intrinsic (natural) frequency of oscillators. The gamma phase-locking, the precise phase relation and the emergent (measurable) frequencies were determined by two principal factors: the detuning (intrinsic frequency difference, i.e. local input difference) and the coupling strength. In addition to frequency coding, gamma phase contained complementary stimulus information. Crucially, the phase code reflected input differences, but not the absolute input level. This property of relative input-to-phase conversion, contrasting with latency

  16. Rheological properties, shape oscillations, and coalescence of liquid drops with surfactants

    NASA Technical Reports Server (NTRS)

    Apfel, R. E.; Holt, R. G.

    1990-01-01

    A method was developed to deduce dynamic interfacial properties of liquid drops. The method involves measuring the frequency and damping of free quadrupole oscillations of an acoustically levitated drop. Experimental results from pure liquid-liquid systems agree well with theoretical predictions. Additionally, the effects of surfactants is considered. Extension of these results to a proposed microgravity experiment on the drop physics module (DPM) in USML-1 are discussed. Efforts are also underway to model the time history of the thickness of the fluid layer between two pre-coalescence drops, and to measure the film thickness experimentally. Preliminary results will be reported, along with plans for coalescence experiments proposed for USML-1.

  17. Nonspherical shape oscillations of coated microbubbles in contact with a wall.

    PubMed

    Vos, Hendrik J; Dollet, Benjamin; Versluis, Michel; de Jong, Nico

    2011-06-01

    In this experimental study, the nonspherical and translational behavior of individual coated microbubbles of different sizes, in contact with a 20-μm thickness cellulose wall, are observed and categorized systematically. Images from two orthogonally positioned microscopes are merged and then recorded with an ultra-fast framing camera. Large nonspherical deformations were found with 2.25 MHz frequency ultrasound pulses having driving pressures from 80 to 325 kPa. A parametric model combining potential flow theory with a viscous boundary layer at the wall is developed and used to calculate stresses from the optically recorded microbubble oscillations. Peak shear stress of up to 300 kPa and normal stresses of up to 1 MPa are estimated when microbubbles are insonifed with a 2.25 MHz pulse at 325 kPa. The clinical relevance of these results is discussed. PMID:21601137

  18. Special Issue on "Neutrino Oscillations: Celebrating the Nobel Prize in Physics 2015" in Nuclear Physics B

    NASA Astrophysics Data System (ADS)

    Ohlsson, Tommy

    2016-07-01

    In 2015, the Nobel Prize in Physics was awarded jointly to Takaaki Kajita from the Super-Kamiokande Collaboration and Arthur B. McDonald from the SNO Collaboration "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Furthermore, the Daya Bay, K2K and T2K, KamLAND, SNO, and Super-Kamiokande Collaborations shared the Fundamental Physics Breakthrough Prize the same year. In order to celebrate this successful and fruitful year for neutrino oscillations, the editors and the publisher of Nuclear Physics B decided to publish a Special Issue on neutrino oscillations. We invited prominent scientists in the area of neutrino physics that relates to neutrino oscillations to write contributions for this Special Issue, which was open to both original research articles as well as review articles. The authors of this Special Issue consist of e.g. the two Nobel Laureates, International Participants of the Nobel Symposium 129 on Neutrino Physics at Haga Slott in Enköping, Sweden (August 19-24, 2004), selected active researchers, and members from large experimental collaborations with major results in the last ten years. In total, this Special Issue consists of 28 contributions. Please note that the cover of this Special Issue contains a figure from each of the 26 contributions that have figures included.

  19. Potential oscillations and S-shaped polarization curve in the continuous electro-oxidation of CO on platinum single-crystal electrodes

    SciTech Connect

    Koper, Marc T.M.; Schmidt, Thomas J.; Markovic, Nenad M.; Ross, Philip N.

    2001-03-01

    The occurrence of an S-shaped polarization curve in a simple model for the continuous electrochemical oxidation of CO on a platinum electrode is discussed. In the model, the S-shaped polarization curve is caused by the competitive Langmuir-Hinshelwood mechanism between surface-bonded CO and OH. The reaction is studied experimentally on single-crystal platinum rotating disk electrodes in perchloric and sulfuric acid solution, and it is shown that the voltammetry is in good agreement with the model predictions. When studied under current-controlled conditions, a fast galvanodynamic scan indeed suggests the existence of the S-shaped polarization curve. At lower scan rates, however, irregularities and small-amplitude irregular fluctuations or oscillations in potential are observed. Very regular potential oscillations under current-controlled conditions are observed only on Pt(111) in sulfuric acid. The possible origin of these irregularities and oscillations is discussed in relation to the existing theories of electrochemical instabilities.

  20. Strain relief and shape oscillations in site-controlled coherent SiGe islands.

    PubMed

    Hrauda, N; Zhang, J J; Groiss, H; Etzelstorfer, T; Holý, V; Bauer, G; Deiter, C; Seeck, O H; Stangl, J

    2013-08-23

    Strain engineering and the crystalline quality of semiconductor nanostructures are important issues for electronic and optoelectronic devices. We report on defect-free SiGe island arrays resulting from Ge coverages of up to 38 monolayers grown on prepatterned Si(001) substrates. This represents a significant expansion of the parameter space known for the growth of perfect island arrays. A cyclic development of the Ge content and island shape was observed while increasing the Ge coverage. Synchrotron-based x-ray diffraction experiments and finite element method calculations allow us to study the strain behavior of such islands in great detail. In contrast to the oscillatory changes of island shape and average Ge content, the overall strain behavior of these islands exhibits a clear monotonic trend of progressive strain relaxation with increasing Ge coverage. PMID:23892543

  1. Strain relief and shape oscillations in site-controlled coherent SiGe islands

    NASA Astrophysics Data System (ADS)

    Hrauda, N.; Zhang, J. J.; Groiss, H.; Etzelstorfer, T.; Holý, V.; Bauer, G.; Deiter, C.; Seeck, O. H.; Stangl, J.

    2013-08-01

    Strain engineering and the crystalline quality of semiconductor nanostructures are important issues for electronic and optoelectronic devices. We report on defect-free SiGe island arrays resulting from Ge coverages of up to 38 monolayers grown on prepatterned Si(001) substrates. This represents a significant expansion of the parameter space known for the growth of perfect island arrays. A cyclic development of the Ge content and island shape was observed while increasing the Ge coverage. Synchrotron-based x-ray diffraction experiments and finite element method calculations allow us to study the strain behavior of such islands in great detail. In contrast to the oscillatory changes of island shape and average Ge content, the overall strain behavior of these islands exhibits a clear monotonic trend of progressive strain relaxation with increasing Ge coverage.

  2. Efficient and automatic calculation of optical band shapes and resonance Raman spectra for larger molecules within the independent mode displaced harmonic oscillator model.

    PubMed

    Petrenko, Taras; Neese, Frank

    2012-12-21

    In this work, an improved method for the efficient automatic simulation of optical band shapes and resonance Raman (rR) intensities within the "independent mode displaced harmonic oscillator" is described. Despite the relative simplicity of this model, it is able to account for the intensity distribution in absorption (ABS), fluorescence, and rR spectra corresponding to strongly dipole allowed electronic transitions with high accuracy. In order to include temperature-induced effects, we propose a simple extension of the time dependent wavepacket formalism developed by Heller which enables one to derive analytical expressions for the intensities of hot bands in ABS and rR spectra from the dependence of the wavepacket evolution on its initial coordinate. We have also greatly optimized the computational procedures for numerical integration of complicated oscillating integrals. This is important for efficient simulations of higher-order rR spectra and excitation profiles, as well as for the fitting of experimental spectra of large molecules. In particular, the multimode damping mechanism is taken into account for efficient reduction of the upper time limit in the numerical integration. Excited state energy gradient as well as excited state geometry optimization calculations are employed in order to determine excited state dimensionless normal coordinate displacements. The gradient techniques are highly cost-effective provided that analytical excited state derivatives with respect to nuclear displacements are available. Through comparison with experimental spectra of some representative molecules, we illustrate that the gradient techniques can even outperform the geometry optimization method if the harmonic approximation becomes inadequate. PMID:23267471

  3. Multidimensionally constrained covariant density functional theories—nuclear shapes and potential energy surfaces

    NASA Astrophysics Data System (ADS)

    Zhou, Shan-Gui

    2016-06-01

    The intrinsic nuclear shapes deviating from a sphere not only manifest themselves in nuclear collective states but also play important roles in determining nuclear potential energy surfaces (PES’s) and fission barriers. In order to describe microscopically and self-consistently nuclear shapes and PES’s with as many shape degrees of freedom as possible included, we developed multidimensionally constrained covariant density functional theories (MDC-CDFTs). In MDC-CDFTs, the axial symmetry and the reflection symmetry are both broken and all deformations characterized by {β }λ μ with even μ are considered. We have used the MDC-CDFTs to study PES’s and fission barriers of actinides, the non-axial octupole Y 32 correlations in N = 150 isotones and shapes of hypernuclei. In this Review we will give briefly the formalism of MDC-CDFTs and present the applications to normal nuclei.

  4. Hepatic circadian clock oscillators and nuclear receptors integrate microbiome-derived signals

    PubMed Central

    Montagner, Alexandra; Korecka, Agata; Polizzi, Arnaud; Lippi, Yannick; Blum, Yuna; Canlet, Cécile; Tremblay-Franco, Marie; Gautier-Stein, Amandine; Burcelin, Rémy; Yen, Yi-Chun; Je, Hyunsoo Shawn; Maha, Al-Asmakh; Mithieux, Gilles; Arulampalam, Velmurugesan; Lagarrigue, Sandrine; Guillou, Hervé; Pettersson, Sven; Wahli, Walter

    2016-01-01

    The liver is a key organ of metabolic homeostasis with functions that oscillate in response to food intake. Although liver and gut microbiome crosstalk has been reported, microbiome-mediated effects on peripheral circadian clocks and their output genes are less well known. Here, we report that germ-free (GF) mice display altered daily oscillation of clock gene expression with a concomitant change in the expression of clock output regulators. Mice exposed to microbes typically exhibit characterized activities of nuclear receptors, some of which (PPARα, LXRβ) regulate specific liver gene expression networks, but these activities are profoundly changed in GF mice. These alterations in microbiome-sensitive gene expression patterns are associated with daily alterations in lipid, glucose, and xenobiotic metabolism, protein turnover, and redox balance, as revealed by hepatic metabolome analyses. Moreover, at the systemic level, daily changes in the abundance of biomarkers such as HDL cholesterol, free fatty acids, FGF21, bilirubin, and lactate depend on the microbiome. Altogether, our results indicate that the microbiome is required for integration of liver clock oscillations that tune output activators and their effectors, thereby regulating metabolic gene expression for optimal liver function. PMID:26879573

  5. Cell volume and shape oscillations in rat type-II somatotrophs at hypotonic conditions.

    PubMed

    Engström, K G; Sävendahl, L

    1995-05-01

    The size and shape of growth hormone (GH)-producing rat type-II somatotrophs was studied during osmotic manipulation. When somatotrophs were exposed to large osmotic stress (200 and 225 mOsm), the peak projected cell area (PCA) was 132.9% +/- 12.6% and 116.8% +/- 2.8% (P < 0.01) and triggered a regulatory volume decrease (RVD) to avoid lysis. At lower osmotic stress (250 mOsm), the rate of swelling was slower, and the volume reached a steady state at 109.4% +/- 2.4% (P < 0.05) and was without RVD. At 275 and 287 mOsm, the swelling was delayed [PCA peak at 3-4 min; 105.8% +/- 1.5% (P < 0.05) and 104.2% +/- 1.7%] and then showed repeated synchronized cycles of swelling and shrink-age (P < 0.05). The data suggest that somatotrophs may have more than one mechanism for volume regulation. One mechanism is for large swelling (classic RVD response), whereas the other represents more physiological mechanisms for regulating the cell volume within a more limited geometry range. For low osmotic stress (250-287 mOsm), the somatotrophs became less spherical during swelling and, thus, were without membrane dilation. Therefore, this type of volume regulation must work independently from membrane stress. Related volume regulation mechanisms may underlie the previously observed volume fluctuations in somatotrophs seen during secretory stimulation with GH-releasing hormone. PMID:7600901

  6. The Min system as a general cell geometry detection mechanism: branch lengths in Y-shaped Escherichia coli cells affect Min oscillation patterns and division dynamics.

    PubMed

    Varma, Archana; Huang, Kerwyn Casey; Young, Kevin D

    2008-03-01

    In Escherichia coli, division site placement is regulated by the dynamic behavior of the MinCDE proteins, which oscillate from pole to pole and confine septation to the centers of normal rod-shaped cells. Some current mathematical models explain these oscillations by considering interactions among the Min proteins without recourse to additional localization signals. So far, such models have been applied only to regularly shaped bacteria, but here we test these models further by employing aberrantly shaped E. coli cells as miniature reactors. The locations of MinCDE proteins fused to derivatives of green fluorescent protein were monitored in branched cells with at least three conspicuous poles. MinCDE most often moved from one branch to another in an invariant order, following a nonreversing clockwise or counterclockwise direction over the time periods observed. In cells with two short branches or nubs, the proteins oscillated symmetrically from one end to the other. The locations of FtsZ rings were consistent with a broad MinC-free zone near the branch junctions, and Min rings exhibited the surprising behavior of moving quickly from one possible position to another. Using a reaction-diffusion model that reproduces the observed MinCD oscillations in rod-shaped and round E. coli, we predict that the oscillation patterns in branched cells are a natural response of Min behavior in cellular geometries having different relative branch lengths. The results provide further evidence that Min protein oscillations act as a general cell geometry detection mechanism that can locate poles even in branched cells. PMID:18178745

  7. Nuclear states and shapes at high spin. [Good review

    SciTech Connect

    Diamond, R.M.

    1980-08-01

    As angular momentum is added to a nucleus, the balance of forces acting upon it to determine its shape, moment of inertia, mode of rotation, and type of level structure may undergo a series of changes. At relatively low spins a deformed nucleus will rotate collectively, and one may see the effect of Coriolis antipairing in gradually increasing the moment of inertia. Around spin 12 to 16 h-bar there may be an abrupt change (backbending) when a pair of high-j nucleons unpairs and the nucleons align with the axis of rotation; this process allows the nucleus to slow its collective rotation. This process, the start of a sharing of angular momentum between single-particle motion and the collective rotation, gives a lower total energy and corresponds to a change toward triaxiality in the shape of the nucleus. At much higher spins discrete ..gamma..-ray transitions can no longer be observed. This is the regime of continuum spectra; all the information on these high-spin states (to 65 h-bar) is contained in these continuum cascades. Knowledge is accumulating on how to study these spectra, experimentally and theoretically, and new techniques offer promise of revealing a great deal of information about the shapes and properties of very high spin states. 71 references, 34 figures.

  8. Mitochondrial and nuclear DNA matching shapes metabolism and healthy ageing.

    PubMed

    Latorre-Pellicer, Ana; Moreno-Loshuertos, Raquel; Lechuga-Vieco, Ana Victoria; Sánchez-Cabo, Fátima; Torroja, Carlos; Acín-Pérez, Rebeca; Calvo, Enrique; Aix, Esther; González-Guerra, Andrés; Logan, Angela; Bernad-Miana, María Luisa; Romanos, Eduardo; Cruz, Raquel; Cogliati, Sara; Sobrino, Beatriz; Carracedo, Ángel; Pérez-Martos, Acisclo; Fernández-Silva, Patricio; Ruíz-Cabello, Jesús; Murphy, Michael P; Flores, Ignacio; Vázquez, Jesús; Enríquez, José Antonio

    2016-07-28

    Human mitochondrial DNA (mtDNA) shows extensive within population sequence variability. Many studies suggest that mtDNA variants may be associated with ageing or diseases, although mechanistic evidence at the molecular level is lacking. Mitochondrial replacement has the potential to prevent transmission of disease-causing oocyte mtDNA. However, extension of this technology requires a comprehensive understanding of the physiological relevance of mtDNA sequence variability and its match with the nuclear-encoded mitochondrial genes. Studies in conplastic animals allow comparison of individuals with the same nuclear genome but different mtDNA variants, and have provided both supporting and refuting evidence that mtDNA variation influences organismal physiology. However, most of these studies did not confirm the conplastic status, focused on younger animals, and did not investigate the full range of physiological and phenotypic variability likely to be influenced by mitochondria. Here we systematically characterized conplastic mice throughout their lifespan using transcriptomic, proteomic,metabolomic, biochemical, physiological and phenotyping studies. We show that mtDNA haplotype profoundly influences mitochondrial proteostasis and reactive oxygen species generation,insulin signalling, obesity, and ageing parameters including telomere shortening and mitochondrial dysfunction, resulting in profound differences in health longevity between conplastic strains. PMID:27383793

  9. Harmonic oscillator representation in the theory of scattering and nuclear reactions

    NASA Technical Reports Server (NTRS)

    Smirnov, Yuri F.; Shirokov, A. M.; Lurie, Yuri, A.; Zaitsev, S. A.

    1995-01-01

    The following questions, concerning the application of the harmonic oscillator representation (HOR) in the theory of scattering and reactions, are discussed: the formulation of the scattering theory in HOR; exact solutions of the free motion Schroedinger equation in HOR; separable expansion of the short range potentials and the calculation of the phase shifts; 'isolated states' as generalization of the Wigner-von Neumann bound states embedded in continuum; a nuclear coupled channel problem in HOR; and the description of true three body scattering in HOR. As an illustration the soft dipole mode in the (11)Li nucleus is considered in a frame of the (9)Li+n+n cluster model taking into account of three body continuum effects.

  10. Oscillator strengths, first-order properties, and nuclear gradients for local ADC(2)

    SciTech Connect

    Schütz, Martin

    2015-06-07

    We describe theory and implementation of oscillator strengths, orbital-relaxed first-order properties, and nuclear gradients for the local algebraic diagrammatic construction scheme through second order. The formalism is derived via time-dependent linear response theory based on a second-order unitary coupled cluster model. The implementation presented here is a modification of our previously developed algorithms for Laplace transform based local time-dependent coupled cluster linear response (CC2LR); the local approximations thus are state specific and adaptive. The symmetry of the Jacobian leads to considerable simplifications relative to the local CC2LR method; as a result, a gradient evaluation is about four times less expensive. Test calculations show that in geometry optimizations, usually very similar geometries are obtained as with the local CC2LR method (provided that a second-order method is applicable). As an exemplary application, we performed geometry optimizations on the low-lying singlet states of chlorophyllide a.

  11. Nuclear-pumped laser operating in the master oscillator-amplifier regime

    SciTech Connect

    Pikulev, A A; Tsvetkov, V M; Sosnin, P V; Sinyanskii, A A

    2008-07-31

    The efficiency of a master oscillator-amplifier scheme and the possibility of its using in multichannel nuclear-pumped laser systems are studied. The small-signal gain and saturation parameter are measured for the He:Ar:Xe = 380:380:1 mixture at a pressure of 1 atm at a wavelength of 2.03 {mu}m. It is shown that the small-signal gain increases linearly with the specific pump power density and achieves 1.1-1.2 m{sup -1} at a pump density of 40 W cm{sup -3}. The saturation parameter is almost independent of the pump power and is equal to 70-90 W cm{sup -2}. It is found that at the pump-pulse maximum (40 W cm{sup -3}) the laser radiation power increases after amplification by 100%. (active media, lasers, and amplifiers)

  12. MOA: Magnetic Field Oscillating Amplified Thruster and its Application for Nuclear Electric and Thermal Propulsion

    SciTech Connect

    Frischauf, Norbert; Hettmer, Manfred; Grassauer, Andreas; Bartusch, Tobias; Koudelka, Otto

    2006-07-01

    More than 60 years after the later Nobel laureate Hannes Alfven had published a letter stating that oscillating magnetic fields can accelerate ionised matter via magneto-hydrodynamic interactions in a wave like fashion, the technical implementation of Alfven waves for propulsive purposes has been proposed, patented and examined for the first time by a group of inventors. The name of the concept, utilising Alfven waves to accelerate ionised matter for propulsive purposes, is MOA - Magnetic field Oscillating Amplified thruster. Alfven waves are generated by making use of two coils, one being permanently powered and serving also as magnetic nozzle, the other one being switched on and off in a cyclic way, deforming the field lines of the overall system. It is this deformation that generates Alfven waves, which are in the next step used to transport and compress the propulsive medium, in theory leading to a propulsion system with a much higher performance than any other electric propulsion system. Based on computer simulations, which were conducted to get a first estimate on the performance of the system, MOA is a highly flexible propulsion system, whose performance parameters might easily be adapted, by changing the mass flow and/or the power level. As such the system is capable to deliver a maximum specific impulse of 13116 s (12.87 mN) at a power level of 11.16 kW, using Xe as propellant, but can also be attuned to provide a thrust of 236.5 mN (2411 s) at 6.15 kW of power. While space propulsion is expected to be the prime application for MOA and is supported by numerous applications such as Solar and/or Nuclear Electric Propulsion or even as an 'afterburner system' for Nuclear Thermal Propulsion, other terrestrial applications can be thought of as well, making the system highly suited for a common space-terrestrial application research and utilisation strategy. (authors)

  13. Feedback control of combustion instabilities from within limit cycle oscillations using H∞ loop-shaping and the ν-gap metric

    PubMed Central

    Morgans, Aimee S.

    2016-01-01

    Combustion instabilities arise owing to a two-way coupling between acoustic waves and unsteady heat release. Oscillation amplitudes successively grow, until nonlinear effects cause saturation into limit cycle oscillations. Feedback control, in which an actuator modifies some combustor input in response to a sensor measurement, can suppress combustion instabilities. Linear feedback controllers are typically designed, using linear combustor models. However, when activated from within limit cycle, the linear model is invalid, and such controllers are not guaranteed to stabilize. This work develops a feedback control strategy guaranteed to stabilize from within limit cycle oscillations. A low-order model of a simple combustor, exhibiting the essential features of more complex systems, is presented. Linear plane acoustic wave modelling is combined with a weakly nonlinear describing function for the flame. The latter is determined numerically using a level set approach. Its implication is that the open-loop transfer function (OLTF) needed for controller design varies with oscillation level. The difference between the mean and the rest of the OLTFs is characterized using the ν-gap metric, providing the minimum required ‘robustness margin’ for an H∞ loop-shaping controller. Such controllers are designed and achieve stability both for linear fluctuations and from within limit cycle oscillations. PMID:27493558

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

    SciTech Connect

    Frederick, B.deB. |

    1994-12-01

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

  15. 250 GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR

    NASA Astrophysics Data System (ADS)

    Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2007-12-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9 T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP enhanced multidimensional NMR. These results include assignment of active site resonances in [U- 13C, 15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as

  16. 250GHz CW gyrotron oscillator for dynamic nuclear polarization in biological solid state NMR.

    PubMed

    Bajaj, Vikram S; Hornstein, Melissa K; Kreischer, Kenneth E; Sirigiri, Jagadishwar R; Woskov, Paul P; Mak-Jurkauskas, Melody L; Herzfeld, Judith; Temkin, Richard J; Griffin, Robert G

    2007-12-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz (1)H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP enhanced multidimensional NMR. These results include assignment of active site resonances in [U-(13)C, (15)N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents

  17. 250 GHz CW Gyrotron Oscillator for Dynamic Nuclear Polarization in Biological Solid State NMR

    PubMed Central

    Bajaj, Vikram S.; Hornstein, Melissa K.; Kreischer, Kenneth E.; Sirigiri, Jagadishwar R.; Woskov, Paul P.; Mak-Jurkauskas, Melody L.; Herzfeld, Judith; Temkin, Richard J.; Griffin, Robert G.

    2009-01-01

    In this paper, we describe a 250 GHz gyrotron oscillator, a critical component of an integrated system for magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments at 9T, corresponding to 380 MHz 1H frequency. The 250 GHz gyrotron is the first gyro-device designed with the goal of seamless integration with an NMR spectrometer for routine DNP-enhanced NMR spectroscopy and has operated under computer control for periods of up to 21 days with a 100% duty cycle. Following a brief historical review of the field, we present studies of the membrane protein bacteriorhodopsin (bR) using DNP-enhanced multidimensional NMR. These results include assignment of active site resonances in [U-13C,15N]-bR and demonstrate the utility of DNP for studies of membrane proteins. Next, we review the theory of gyro-devices from quantum mechanical and classical viewpoints and discuss the unique considerations that apply to gyrotron oscillators designed for DNP experiments. We then characterize the operation of the 250 GHz gyrotron in detail, including its long-term stability and controllability. We have measured the spectral purity of the gyrotron emission using both homodyne and heterodyne techniques. Radiation intensity patterns from the corrugated waveguide that delivers power to the NMR probe were measured using two new techniques to confirm pure mode content: a thermometric approach based on the temperature-dependent color of liquid crystalline media applied to a substrate and imaging with a pyroelectric camera. We next present a detailed study of the mode excitation characteristics of the gyrotron. Exploration of the operating characteristics of several fundamental modes reveals broadband continuous frequency tuning of up to 1.8 GHz as a function of the magnetic field alone, a feature that may be exploited in future tunable gyrotron designs. Oscillation of the 250 GHz gyrotron at the second harmonic of cyclotron resonance begins at extremely low beam currents (as low

  18. Rapid and Sustained Nuclear-Cytoplasmic ERK Oscillations Induced by Epidermal Growth Factor

    SciTech Connect

    Shankaran, Harish; Ippolito, Danielle L.; Chrisler, William B.; Resat, Haluk; Bollinger, Nikki; Opresko, Lee K.; Wiley, H. S.

    2009-12-01

    Mathematical modeling has predicted that ERK activity should oscillate in response to cell stimulation, but this has never been observed. To explore this inconsistency, we expressed an ERK1-GFP fusion protein in mammary epithelial cells. Following EGF stimulation, we observed rapid and continuous ERK oscillations between the nucleus and cytoplasm with a periodicity of approximately 15 minutes. These oscillations were remarkably persistent (>45 cycles), displayed an asymmetric waveform, and were highly dependent on cell density, essentially disappearing at confluency. We conclude that the ERK pathway is an intrinsic oscillator. Although the functional implications of the observed oscillations are uncertain, this property can be used to continuously monitor ERK activity in single cells.

  19. System for determining the type of nuclear radiation from detector output pulse shape

    DOEpatents

    Miller, W.H.; Berliner, R.R.

    1994-09-13

    A radiation detection system determines the type of nuclear radiation received in a detector by producing a correlation value representative of the statistical cross correlation between the shape of the detector signal and pulse shape data previously stored in memory and characteristic of respective types of radiation. The correlation value is indicative of the type of radiation. The energy of the radiation is determined from the detector signal and is used to produce a spectrum of radiation energies according to radiation type for indicating the nature of the material producing the radiation. 2 figs.

  20. System for determining the type of nuclear radiation from detector output pulse shape

    DOEpatents

    Miller, William H.; Berliner, Ronald R.

    1994-01-01

    A radiation detection system determines the type of nuclear radiation received in a detector by producing a correlation value representative of the statistical cross correlation between the shape of the detector signal and pulse shape data previously stored in memory and characteristic of respective types of radiation. The correlation value is indicative of the type of radiation. The energy of the radiation is determined from the detector signal and is used to produce a spectrum of radiation energies according to radiation type for indicating the nature of the material producing the radiation.

  1. Temperature oscillations near natural nuclear reactor cores and the potential for prebiotic oligomer synthesis

    NASA Astrophysics Data System (ADS)

    Adam, Zachary R.

    2016-06-01

    Geologic settings capable of driving prebiotic oligomer synthesis reactions remain a relatively unexplored aspect of origins of life research. Natural nuclear reactors are an example of Precambrian energy sources that produced unique temperature fluctuations. Heat transfer models indicate that water-moderated, convectively-cooled natural fission reactors in porous host rocks create temperature oscillations that resemble those employed in polymerase chain reaction (PCR) devices to artificially amplify oligonucleotides. This temperature profile is characterized by short-duration pulses up to 70-100 °C, followed by a sustained period of temperatures in the range of 30-70 °C, and finally a period of relaxation to ambient temperatures until the cycle is restarted by a fresh influx of pore water. For a given reactor configuration, temperature maxima and the time required to relax to ambient temperatures depend most strongly on the aggregate effect of host rock permeability in decreasing the thermal expansion and increasing the viscosity and evaporation temperature of the pore fluids. Once formed, fission-fueled reactors can sustain multi-kilowatt-level power production for 105-106 years, ensuring microenvironmental longevity and chemical output. The model outputs indicate that organic synthesis on young planetary bodies with a sizeable reservoir of fissile material can involve more sophisticated energy dissipation pathways than modern terrestrial analog settings alone would suggest.

  2. Temperature oscillations near natural nuclear reactor cores and the potential for prebiotic oligomer synthesis.

    PubMed

    Adam, Zachary R

    2016-06-01

    Geologic settings capable of driving prebiotic oligomer synthesis reactions remain a relatively unexplored aspect of origins of life research. Natural nuclear reactors are an example of Precambrian energy sources that produced unique temperature fluctuations. Heat transfer models indicate that water-moderated, convectively-cooled natural fission reactors in porous host rocks create temperature oscillations that resemble those employed in polymerase chain reaction (PCR) devices to artificially amplify oligonucleotides. This temperature profile is characterized by short-duration pulses up to 70-100 °C, followed by a sustained period of temperatures in the range of 30-70 °C, and finally a period of relaxation to ambient temperatures until the cycle is restarted by a fresh influx of pore water. For a given reactor configuration, temperature maxima and the time required to relax to ambient temperatures depend most strongly on the aggregate effect of host rock permeability in decreasing the thermal expansion and increasing the viscosity and evaporation temperature of the pore fluids. Once formed, fission-fueled reactors can sustain multi-kilowatt-level power production for 10(5)-10(6) years, ensuring microenvironmental longevity and chemical output. The model outputs indicate that organic synthesis on young planetary bodies with a sizeable reservoir of fissile material can involve more sophisticated energy dissipation pathways than modern terrestrial analog settings alone would suggest. PMID:26680444

  3. Raindrop oscillations

    NASA Technical Reports Server (NTRS)

    Beard, K. V.

    1982-01-01

    A model of the change in shape of a raindrop is presented. Raindrops measured by two orthogonal cameras were classified by shape and orientation to determine the nature of the oscillation. A physical model based on potential energy was then developed to study the amplitude variation of oscillating drops. The model results show that oscillations occur about the equilibrium axis ratio, but the time average axis ratio if significantly more spherical for large amplitudes because of asymmetry in the surface potential energy. A generalization of the model to oscillations produced by turbulence yields average axis ratios that are consistent with the camera measurements. The model results for average axis ratios were applied to rainfall studies with a dual polarized radar.

  4. Universally Conserved Relationships between Nuclear Shape and Cytoplasmic Mechanical Properties in Human Stem Cells

    NASA Astrophysics Data System (ADS)

    Lozoya, Oswaldo A.; Gilchrist, Christopher L.; Guilak, Farshid

    2016-03-01

    The ability of cells to proliferate, differentiate, transduce extracellular signals and assemble tissues involves structural connections between nucleus and cytoskeleton. Yet, how the mechanics of these connections vary inside stem cells is not fully understood. To address those questions, we combined two-dimensional particle-tracking microrheology and morphological measures using variable reduction techniques to measure whether cytoplasmic mechanics allow for discrimination between different human adherent stem cell types and across different culture conditions. Here we show that nuclear shape is a quantifiable discriminant of mechanical properties in the perinuclear cytoskeleton (pnCSK) of various stem cell types. Also, we find the pnCSK is a region with different mechanical properties than elsewhere in the cytoskeleton, with heterogeneously distributed locations exhibiting subdiffusive features, and which obeys physical relations conserved among various stem cell types. Finally, we offer a prospective basis to discriminate between stem cell types by coupling perinuclear mechanical properties to nuclear shape.

  5. Nuclear shape transitions in neutron-rich medium-mass nuclei

    SciTech Connect

    Sarriguren, P.; Rodriguez-Guzman, R.; Robledo, L. M.

    2012-10-20

    We study the isotopic evolution of the ground-state nuclear shapes in neutron-rich Kr, Rb, Sr, Y, Zr, Nb, and Mo isotopic chains. Both even-even and odd-A nuclei are included in the analysis. For the latter we also study the systematics of their one-quasiparticle low-lying configurations. The theoretical approach is based on a selfconsistent Hartree-Fock-Bogoliubov formalism with finite range Gogny energy density functionals. Neutron separation energies, charge radii, and the spin-parity of the ground states are calculated and compared with available data. Shape-transition signatures are identified around N= 60 isotones as discontinuities in both charge radii isotopic shifts and spin-parities of the ground states. The nuclear deformation including triaxiality is shown to play a relevant role in the understanding of the bulk and spectroscopic features of the ground and low-lying one-quasiparticle states.

  6. Universally Conserved Relationships between Nuclear Shape and Cytoplasmic Mechanical Properties in Human Stem Cells

    PubMed Central

    Lozoya, Oswaldo A.; Gilchrist, Christopher L.; Guilak, Farshid

    2016-01-01

    The ability of cells to proliferate, differentiate, transduce extracellular signals and assemble tissues involves structural connections between nucleus and cytoskeleton. Yet, how the mechanics of these connections vary inside stem cells is not fully understood. To address those questions, we combined two-dimensional particle-tracking microrheology and morphological measures using variable reduction techniques to measure whether cytoplasmic mechanics allow for discrimination between different human adherent stem cell types and across different culture conditions. Here we show that nuclear shape is a quantifiable discriminant of mechanical properties in the perinuclear cytoskeleton (pnCSK) of various stem cell types. Also, we find the pnCSK is a region with different mechanical properties than elsewhere in the cytoskeleton, with heterogeneously distributed locations exhibiting subdiffusive features, and which obeys physical relations conserved among various stem cell types. Finally, we offer a prospective basis to discriminate between stem cell types by coupling perinuclear mechanical properties to nuclear shape. PMID:26976044

  7. Nuclear shape coexistence in Po isotopes: An interacting boson model study

    NASA Astrophysics Data System (ADS)

    García-Ramos, J. E.; Heyde, K.

    2015-09-01

    Background: The lead region, Po, Pb, Hg, and Pt, shows up the presence of coexisting structures having different deformation and corresponding to different particle-hole configurations in the shell-model language. Purpose: We intend to study the importance of configuration mixing in the understanding of the nuclear structure of even-even Po isotopes, where the shape coexistence phenomena are not clear enough. Method: We study in detail a long chain of polonium isotopes, Po-208190, using the interacting boson model with configuration mixing (IBM-CM). We fix the parameters of the Hamiltonians through a least-squares fit to the known energies and absolute B (E 2 ) transition rates of states up to 3 MeV. Results: We obtained the IBM-CM Hamiltonians and we calculate excitation energies, B (E 2 ) 's, electric quadrupole moments, nuclear radii and isotopic shifts, quadrupole shape invariants, wave functions, and deformations. Conclusions: We obtain a good agreement with the experimental data for all the studied observables and we conclude that shape coexistence phenomenon is hidden in Po isotopes, very much as in the case of the Pt isotopes.

  8. Oxydative stress alters nuclear shape through lamins dysregulation: a route to senescence.

    PubMed

    Barascu, Aurélia; Le Chalony, Catherine; Pennarun, Gaëlle; Genet, Diane; Zaarour, Nancy; Bertrand, Pascale

    2012-01-01

    Progeroid phenotypes are mainly encountered in 2 types of syndromes: in laminopathies, which are characterized by nuclear shape abnormalities due to lamin A alteration, and in DNA damage response defect syndromes. Because lamin A dysregulation leads to DNA damages, it has been proposed that senescence occurs in both types of syndromes through the accumulation of damages. We recently showed that elevated oxidative stress is responsible for lamin B1 accumulation, nuclear shape alteration and senescence in the DDR syndrome, ataxia telangiectasia (A-T). Interestingly, overexpression of lamin B1 in wild type cells is sufficient to induce senescence without the induction of DNA damages. Here, we will discuss the importance of controlling the lamins level in order for maintenance nuclear architecture and we will comment the relationships of lamins with other senescence mechanisms. Finally, we will describe emerging data reporting redox control by lamins, leading us to propose a general mechanism by which reactive oxygen species can induce senescence through lamin dysregulation and NSA. PMID:22895091

  9. Extreme nuclear shapes examined via giant dipole resonance lineshapes in hot light-mass systems

    SciTech Connect

    Pandit, Deepak; Mukhopadhyay, S.; Pal, Surajit; Bhattacharya, S.; Bhattacharya, C.; Banerjee, K.; Kundu, S.; Rana, T. K.; Dey, A.; Mukherjee, G.; Ghosh, T.; Banerjee, S. R.; De, A.; Gupta, D.

    2010-06-15

    The influence of alpha clustering on nuclear reaction dynamics is investigated using the giant dipole resonance (GDR) lineshape studies in the reactions {sup 20}Ne (E{sub lab}=145,160 MeV) + {sup 12}C and {sup 20}Ne (E{sub lab}=160 MeV) + {sup 27}Al, populating {sup 32}S and {sup 47}V, respectively. The GDR lineshapes from the two systems are remarkably different from each other. Whereas, the non-alpha-like {sup 47}V undergoes Jacobi shape transition and matches exceptionally well with the theoretical GDR lineshape estimated under the framework rotating liquid drop model (RLDM) and thermal shape fluctuation model (TSFM) signifying shape equilibration, for the alpha cluster {sup 32}S an extended prolate kind of shape is observed. This unusual deformation, seen directly via gamma decay for the first time, is predicted to be due to the formation of orbiting dinuclear configuration or molecular structure of {sup 16}O + {sup 16}O in the {sup 32}S superdeformed band.

  10. Altering the cellular mechanical force balance results in integrated changes in cell, cytoskeletal and nuclear shape

    NASA Technical Reports Server (NTRS)

    Sims, J. R.; Karp, S.; Ingber, D. E.

    1992-01-01

    Studies were carried out with capillary endothelial cells cultured on fibronectin (FN)-coated dishes in order to analyze the mechanism of cell and nuclear shape control by extracellular matrix (ECM). To examine the role of the cytoskeleton in shape determination independent of changes in transmembrane osmotic pressure, membranes of adherent cells were permeabilized with saponin (25 micrograms/ml) using a buffer that maintains the functional integrity of contractile microfilaments. Real-time videomicroscopic studies revealed that addition of 250 microM ATP resulted in time-dependent retraction and rounding of permeabilized cells and nuclei in a manner similar to that observed in intact living cells following detachment using trypsin-EDTA. Computerized image analysis confirmed that permeabilized cells remained essentially rigid in the absence of ATP and that retraction was stimulated in a dose-dependent manner as the concentration of ATP was raised from 10 to 250 microM. Maximal rounding occurred by 30 min with projected cell and nuclear areas being reduced by 69 and 41%, respectively. ATP-induced rounding was also accompanied by a redistribution of microfilaments resulting in formation of a dense net of F-actin surrounding retracted nuclei. Importantly, ATP-stimulated changes in cell, cytoskeletal, and nuclear form were prevented in permeabilized cells using a synthetic myosin peptide (IRICRKG) that has been previously shown to inhibit actomyosin filament sliding in muscle. In contrast, both the rate and extent of cell and nuclear rounding were increased in permeabilized cells exposed to ATP when the soluble FN peptide, GRGDSP, was used to dislodge immobilized FN from cell surface integrin receptors.(ABSTRACT TRUNCATED AT 250 WORDS).

  11. Frequency characteristics of nuclear spin oscillator with an artificial feedback toward search for 129Xe atomic electric dipole moment

    NASA Astrophysics Data System (ADS)

    Inoue, Takeshi; Furukawa, Takeshi; Yoshimi, Akihiro; Nanao, Tsubasa; Chikamori, Masatoshi; Suzuki, Kunifumi; Hayashi, Hironori; Miyatake, Hirokazu; Ichikawa, Yuichi; Tsuchiya, Masato; Hatakeyama, Naoto; Kagami, Sota; Uchida, Makoto; Ueno, Hideki; Matsuo, Yukari; Fukuyama, Takeshi; Asahi, Koichiro

    2016-06-01

    A 129Xe nuclear spin oscillator with an artificial feedback was constructed, and detailed studies were conducted on its performance, focusing on the frequency stability. As a result, the major sources of drift of the precession frequency in the present spin oscillator setup were identified to be drifts of a solenoid current and an environmental magnetic field. By introducing stabilization systems for the current and the environmental field, which yielded improvements by one order of magnitude on the solenoid current and by a factor of three on the environmental field, a frequency precision of 7.9 nHz was obtained for a one-shot measurement of 3 × 104 s duration. We found, however, that the Allan deviation leveled off at around 30 μHz, indicating a strong need for the precision monitor of the experimental conditions represented by magnetometry. The frequency stability of the spin oscillator is discussed in relation to an experimental search for an electric dipole moment of the 129Xe atom.

  12. Model for the dynamics of a spherical bubble undergoing small shape oscillations between parallel soft elastic layers.

    PubMed

    Hay, Todd A; Ilinskii, Yurii A; Zabolotskaya, Evgenia A; Hamilton, Mark F

    2013-08-01

    A model is developed for a pulsating and translating gas bubble immersed in liquid in a channel formed by two soft, thin elastic parallel layers having densities equal to that of the surrounding liquid and small, but finite, shear moduli. The bubble is nominally spherical but free to undergo small shape deformations. Shear strain in the elastic layers is estimated in a way which is valid for short, transient excitations of the system. Coupled nonlinear second-order differential equations are obtained for the shape and position of the bubble, and numerical integration of an expression for the liquid velocity at the layer interfaces yields an estimate of the elastic layer displacement. Numerical integration of the dynamical equations reveals behavior consistent with laboratory observations of acoustically excited bubbles in ex vivo vessels reported by Chen et al. [Phys. Rev. Lett. 106, 034301 (2011) and Ultrasound Med. Biol. 37, 2139-2148 (2011)]. PMID:23927185

  13. Compact high power mid-infrared optical parametric oscillator pumped by a gain-switched fiber laser with "figure-of-h" pulse shape.

    PubMed

    Jiang, Peipei; Chen, Tao; Wu, Bo; Yang, Dingzhong; Hu, Chengzhi; Wu, Pinghui; Shen, Yonghang

    2015-02-01

    We demonstrate a compact high power mid-infrared (MIR) optical parametric oscillator (OPO) pumped by a gain-switched linearly polarized, pulsed fiber laser. The gain-switched fiber laser was constructed with a piece of Yb doped polarization maintaining (PM) fiber, a pair of fiber Bragg gratings written into the matched passive PM fiber and 6 pigtailed pump laser diodes working at 915 nm with 30 W output peak power each. By modulating the pulse width of the pump laser diode, simple pedestal-free pulse shape or pedestal-free trailing pulse shape ("figure-of-h" as we call it) could be achieved from the gain-switched fiber laser. The laser was employed as the pump of a two-channel, periodically poled magnesium oxide lithium niobate-based OPO system. High power MIR emission was generated with average output power of 5.15 W at 3.8 μm channel and 8.54 W at 3.3 μm channel under the highest pump power of 45 W. The corresponding pump-to-idler conversion efficiency was computed to be 11.7% and 19.1%, respectively. Experimental results verify a significant improvement to signal-to-idler conversion efficiency by using "figure-of-h" pulses over simple pedestal-free pulses. Compared to the master oscillator power amplifier (MOPA) fiber laser counterpart, the presented gain switched fiber laser is more attractive in OPO pumping due to its compactness and simplicity which are beneficial to construction of OPO systems for practical MIR applications. PMID:25836126

  14. Alpha-particles as probes of nuclear shape and structure effects in proton evaporation spectra

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. ); Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A. ); Griffin, H.C. )

    1990-01-01

    The emission barriers and subbarrier anisotropies in the alpha-particle decay with respect to the spin direction on Sn and rare earth compound nuclei are examined in the light of recent calculations incorporating deformation effects in the decay process. For the Sn systems the spectral shapes and anisotropies can be examined without involving deformation. For the rare earth systems deformation which increases with spin is necessary to explain the data. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr ({sup 34}S, 2p2n){sup 82}Sr reaction were measured in coincidence with discrete transitions. Large shifts in proton spectra were observed when high spin states in different rotational bands are populated. These effects cannot be explained by statistical model calculations that do not include explicitly nuclear structure effects in the deexcitation process. They are interpreted as due to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons.

  15. Software emulator of nuclear pulse generation with different pulse shapes and pile-up

    NASA Astrophysics Data System (ADS)

    Pechousek, Jiri; Konecny, Daniel; Novak, Petr; Kouril, Lukas; Kohout, Pavel; Celiktas, Cuneyt; Vujtek, Milan

    2016-08-01

    The optimal detection of output signals from nuclear counting devices represents one of the key physical factors that govern accuracy and experimental reproducibility. In this context, the fine calibration of the detector under diverse experimental scenarios, although time costly, is necessary. However this process can be rendered easier with the use of systems that work in lieu of emulators. In this report we describe an innovative programmable pulse generator device capable to emulate the scintillation detector signals, in a way to mimic the detector performances under a variety of experimental conditions. The emulator generates a defined number of pulses, with a given shape and amplitude in the form of a sampled detector signal. The emulator output is then used off-line by a spectrometric system in order to set up its optimal performance. Three types of pulse shapes are produced by our device, with the possibility to add noise and pulse pile-up effects into the signal. The efficiency of the pulse detection, pile-up rejection and/or correction, together with the dead-time of the system, are therein analyzed through the use of some specific algorithms for pulse processing, and the results obtained validate the beneficial use of emulators for the accurate calibration process of spectrometric systems.

  16. Precision measurement of a low-loss cylindrical dumbbell-shaped sapphire mechanical oscillator using radiation pressure

    NASA Astrophysics Data System (ADS)

    Bourhill, J.; Ivanov, E.; Tobar, M. E.

    2015-08-01

    We present first results from a number of experiments conducted on a 0.53-kg cylindrical dumbbell-shaped sapphire crystal. Here we report on an optomechanical experiment utilizing a modification to the typical cylindrical architecture. Mechanical motion of the crystal structure alters the dimensions of the crystal, and the induced strain changes the permittivity. These two effects result in parametric frequency modulation of resonant microwave whispering gallery modes that are simultaneously excited within the crystal. A microwave readout system is implemented, allowing extremely low noise measurements of this frequency modulation near our modes of interest, having a phase noise floor of -165 dBc/Hz at 100 kHz. Fine tuning of the crystal's suspension has allowed for the optimization of mechanical quality factors in preparation for cryogenic experiments, with a value of Q =8 ×107 achieved at 127 kHz. This results in a Q ×f product of 1013, equivalent to the best measured values in a macroscopic sapphire mechanical system. Results are presented that demonstrate the excitation of mechanical modes via radiation pressure force, allowing an experimental method of determining the transducer's displacement sensitivity d f /d x and calibrating the system. Finally, we demonstrate parametric backaction phenomenon within the system. These are all important steps towards the goal of achieving quantum limited measurements of a kilogram-scale macroscopic device for the purpose of detecting deviations from standard quantum theory resulting from quantum gravitational effects.

  17. Theory of damped quantum rotation in nuclear magnetic resonance spectra. III. Nuclear permutation symmetry of the line shape equation.

    PubMed

    Szymański, S

    2009-12-28

    The damped quantum rotation (DQR) theory describes manifestations in nuclear magnetic resonance spectra of the coherent and stochastic dynamics of N-fold molecular rotors composed of indistinguishable particles. The standard jump model is only a limiting case of the DQR approach; outside this limit, the stochastic motions of such rotors have no kinematic description. In this paper, completing the previous two of this series, consequences of nuclear permutation symmetry for the properties of the DQR line shape equation are considered. The systems addressed are planar rotors, such as aromatic hydrocarbons' rings, occurring inside of molecular crystals oriented in the magnetic field. Under such conditions, oddfold rotors can have nontrivial permutation symmetries only for peculiar orientations while evenfold ones always retain their intrinsic symmetry element, which is rotation by 180 degrees about the N-fold axis; in specific orientations the latter can gain two additional symmetry elements. It is shown that the symmetry selection rules applicable to the classical rate processes in fluids, once recognized as having two diverse aspects, macroscopic and microscopic, are also rigorously valid for the DQR processes in the solid state. However, formal justification of these rules is different because the DQR equation is based on the Pauli principle, which is ignored in the jump model. For objects like the benzene ring, exploitation of these rules in simulations of spectra using the DQR equation can be of critical significance for the feasibility of the calculations. Examples of such calculations for the proton system of the benzene ring in a general orientation are provided. It is also shown that, because of the intrinsic symmetries of the evenfold rotors, many of the DQR processes, which such rotors can undergo, are unobservable in NMR spectra. PMID:20059076

  18. Brownian shape motion on five-dimensional potential-energy surfaces:nuclear fission-fragment mass distributions.

    PubMed

    Randrup, Jørgen; Möller, Peter

    2011-04-01

    Although nuclear fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the fission-fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value. PMID:21517377

  19. Brownian Shape Motion on Five-Dimensional Potential-Energy Surfaces:Nuclear Fission-Fragment Mass Distributions

    SciTech Connect

    Randrup, Joergen; Moeller, Peter

    2011-04-01

    Although nuclear fission can be understood qualitatively as an evolution of the nuclear shape, a quantitative description has proven to be very elusive. In particular, until now, there existed no model with demonstrated predictive power for the fission-fragment mass yields. Exploiting the expected strongly damped character of nuclear dynamics, we treat the nuclear shape evolution in analogy with Brownian motion and perform random walks on five-dimensional fission potential-energy surfaces which were calculated previously and are the most comprehensive available. Test applications give good reproduction of highly variable experimental mass yields. This novel general approach requires only a single new global parameter, namely, the critical neck size at which the mass split is frozen in, and the results are remarkably insensitive to its specific value.

  20. SevenOperators, a Mathematica script for harmonic oscillator nuclear matrix elements arising in semileptonic electroweak interactions

    NASA Astrophysics Data System (ADS)

    Haxton, Wick; Lunardini, Cecilia

    2008-09-01

    Semi-leptonic electroweak interactions in nuclei—such as β decay, μ capture, charged- and neutral-current neutrino reactions, and electron scattering—are described by a set of multipole operators carrying definite parity and angular momentum, obtained by projection from the underlying nuclear charge and three-current operators. If these nuclear operators are approximated by their one-body forms and expanded in the nucleon velocity through order |p→|/M, where p→ and M are the nucleon momentum and mass, a set of seven multipole operators is obtained. Nuclear structure calculations are often performed in a basis of Slater determinants formed from harmonic oscillator orbitals, a choice that allows translational invariance to be preserved. Harmonic-oscillator single-particle matrix elements of the multipole operators can be evaluated analytically and expressed in terms of finite polynomials in q, where q is the magnitude of the three-momentum transfer. While results for such matrix elements are available in tabular form, with certain restriction on quantum numbers, the task of determining the analytic form of a response function can still be quite tedious, requiring the folding of the tabulated matrix elements with the nuclear density matrix, and subsequent algebra to evaluate products of operators. Here we provide a Mathematica script for generating these matrix elements, which will allow users to carry out all such calculations by symbolic manipulation. This will eliminate the errors that may accompany hand calculations and speed the calculation of electroweak nuclear cross sections and rates. We illustrate the use of the new script by calculating the cross sections for charged- and neutral-current neutrino scattering in 12C. Program summaryProgram title: SevenOperators Catalogue identifier: AEAY_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEAY_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland

  1. Nuclear Data Library Effects on Fast to Thermal Flux Shapes Around PWR Control Rod Tips

    NASA Astrophysics Data System (ADS)

    Vasiliev, A.; Ferroukhi, H.; Zhu, T.; Pautz, A.

    2014-04-01

    The development of a high-fidelity computational scheme to estimate the accumulated fluence at the tips of PWR control rods (CR) has been initiated at the Paul Scherrer Institut (PSI). Both the fluence from high-energy (E>1 MeV) neutrons as well as for the thermal range (E<0.625 eV) are required as these affect the CR integrity through stresses/strains induced by coupled clad embrittlement / absorber swelling phenomena. The concept of the PSI scheme under development is to provide from validated core analysis models, the volumetric neutron source to a full core MCNPX model that is then used to compute the neutron fluxes. A particular aspect that needs scrutiny is the ability of the MCNPX-based calculation methodology to accurately predict the flux shapes along the control rod surfaces, especially for fully withdrawn CRs. In that case, the tip is located a short distance above the core/reflector interface and since this situation corresponds to a large part of reactor operation, the accumulated fluence will highly depend on the achieved calculation accuracy and precision in this non-fueled zone. The objective of the work presented in this paper is to quantify the influence of nuclear data on the calculated fluxes at the CR tips by (1) conducting a systematic comparison of modern neutron cross-section libraries, including JENDL-4.0, JEFF-3.1.1 and ENDF/B-VII.0, and (2) by quantifying the uncertainties in the neutron flux calculations with the help of available neutron cross-section variances/covariances data. For completeness, the magnitude of these nuclear data-based uncertainties is also assessed in relation to the influence from other typical sources of modeling uncertainties/biases.

  2. N6-isopentenyladenosine improves nuclear shape in fibroblasts from humans with progeroid syndromes by inhibiting the farnesylation of prelamin A.

    PubMed

    Bifulco, Maurizio; D'Alessandro, Alba; Paladino, Simona; Malfitano, Anna M; Notarnicola, Maria; Caruso, Maria G; Laezza, Chiara

    2013-12-01

    Hutchinson-Gilford progeria syndrome is caused by mutations in the lamin A/C gene that lead to expression of a truncated, permanently farnesylated prelamin A variant called progerin. The accumulation of progerin at the nuclear envelope causes mis-shapen nuclei and results in progeroid syndromes. Previous studies in cells from individuals with Hutchinson-Gilford progeria syndrome have shown that blocking of farnesylation of prelamin A ameliorates the nuclear shape abnormalities. Here we observed that an inhibitor of farnesyl diphosphate synthase, N6-isopentenyladenosine, impeded the farnesylation of prelamin A, causing a decrease in the frequency of nuclear shape abnormalities and redistribution of prelamin A away from the inner nuclear envelope. A combination of lovastatin and N6-isopentenyladenosine significantly improved nuclear shape in fibroblast cell lines from atypical progeria patients. These findings establish a paradigm for ameliorating the most obvious cellular pathology in lamin-related progeroid syndromes, and suggest a potential strategy for treating children with Hutchinson-Gilford progeria syndrome. PMID:24112551

  3. Transverse Isotropy: Disappearance of Mott oscillations in sub-barrier elastic scattering of identical heavy ions and the nuclear ineraction

    NASA Astrophysics Data System (ADS)

    Hussein, Mahir; Canto, L. Felipe; Donangelo, Raul

    2015-04-01

    It is found that at a certain critical value of the Sommerfeld parameter the Mott oscillations usually present in the scattering of identical heavy ions, disappear and the cross section becomes quite flat. We call this effect Transverse Isotropy (TI) (L. F. Canto, R. Donangelo and M. S. Hussein, Mod. Phys. Lett. A, 16), 1027 (2001). The critical value of the Sommerfeld parameter at which TI sets in is found to be ηc =√{ 3 s + 2 } , where s is the spin of the nuclei participating in the scattering. No TI is found in the Mott scattering of identical Fermionic nuclei. The critical center of mass energy corresponding to ηc is found to be Ec = 0.40 MeV for α + α (s = 0), and 1.2 MeV for 6 Li + 6 LI (s = 1). We further found that the inclusion of the nuclear interaction induces a significant modification in the TI. This can be verified by calculating the second derivative of the cross section at θ =90° . We suggest measurements at these sub-barrier energies for the purpose of extracting useful information about the nuclear interaction between light heavy ions. Supported by CNPq, FAPESP, FAPERJ, CAPES/ITA.

  4. Oscillator strengths and radiative decay rates for spin-changing S-P transitions in helium: finite nuclear mass effects

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Schulhoff, Eva E.; Drake, G. W. F.

    2015-12-01

    We have calculated the electric dipole (E1) and magnetic quadrupole (M2) oscillator strengths and spontaneous decay rates for 24 spin-changing transitions of atomic helium. We included the effects of the finite nuclear mass and the anomalous magnetic moment of the electron augmented by the recently derived Pachucki term. The specific transitions for 4He are n{ }1{{{S}}}0-{n}\\prime { }3{{{P}}}{1,2} and n{ }3{{{S}}}1-{n}\\prime { }1{{{P}}}1 with n,{n}\\prime ≤slant 3 and n≤slant 10 for {n}\\prime =n. For the E1 calculations we used the Breit approximation and pseudostate expansions to perform the perturbation sums over intermediate states in both the length and velocity gauge as a check on both numerical accuracy and validity of the transition operators. The corrections for the nuclear mass and the electron anomaly tend to cancel, indicating that if one is included, then so should be the other. The tables give mass- and anomaly-dependent coefficients permitting the easy generation of results for the other isotopes of helium.

  5. Pulse-shape discrimination between electron and nuclear recoils in a NaI(Tl) crystal

    NASA Astrophysics Data System (ADS)

    Lee, H. S.; Adhikari, G.; Adhikari, P.; Choi, S.; Hahn, I. S.; Jeon, E. J.; Joo, H. W.; Kang, W. G.; Kim, G. B.; Kim, H. J.; Kim, H. O.; Kim, K. W.; Kim, N. Y.; Kim, S. K.; Kim, Y. D.; Kim, Y. H.; Lee, J. H.; Lee, M. H.; Leonard, D. S.; Li, J.; Oh, S. Y.; Olsen, S. L.; Park, H. K.; Park, H. S.; Park, K. S.; Shim, J. H.; So, J. H.

    2015-08-01

    We report on the response of a high light-output NaI(Tl) crystal to nuclear recoils induced by neutrons from an Am-Be source and compare the results with the response to electron recoils produced by Compton-scattered 662 keV γ-rays from a 137Cs source. The measured pulse-shape discrimination (PSD) power of the NaI(Tl) crystal is found to be significantly improved because of the high light output of the NaI(Tl) detector. We quantify the PSD power with a quality factor and estimate the sensitivity to the interaction rate for weakly interacting massive particles (WIMPs) with nucleons, and the result is compared with the annual modulation amplitude observed by the DAMA/LIBRA experiment. The sensitivity to spin-independent WIMP-nucleon interactions based on 100 kg·year of data from NaI detectors is estimated with simulated experiments, using the standard halo model.

  6. Nuclear spatial delocalization silences electron density oscillations in 2-phenyl-ethyl-amine (PEA) and 2-phenylethyl-N,N-dimethylamine (PENNA) cations

    NASA Astrophysics Data System (ADS)

    Jenkins, Andrew J.; Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A.

    2016-03-01

    We simulate electron dynamics following ionization in 2-phenyl-ethyl-amine and 2-phenylethyl-N,N-dimethylamine as examples of systems where 3 coupled cationic states are involved. We study two nuclear effects on electron dynamics: (i) coupled electron-nuclear motion and (ii) nuclear spatial delocalization as a result of the zero-point energy in the neutral molecule. Within the Ehrenfest approximation, our calculations show that the coherent electron dynamics in these molecules is not lost as a result of coupled electron-nuclear motion. In contrast, as a result of nuclear spatial delocalization, dephasing of the oscillations occurs on a time scale of only a few fs, long before any significant nuclear motion can occur. The results have been rationalized using a semi-quantitative model based upon the gradients of the potential energy surfaces.

  7. Nuclear spatial delocalization silences electron density oscillations in 2-phenyl-ethyl-amine (PEA) and 2-phenylethyl-N,N-dimethylamine (PENNA) cations.

    PubMed

    Jenkins, Andrew J; Vacher, Morgane; Bearpark, Michael J; Robb, Michael A

    2016-03-14

    We simulate electron dynamics following ionization in 2-phenyl-ethyl-amine and 2-phenylethyl-N,N-dimethylamine as examples of systems where 3 coupled cationic states are involved. We study two nuclear effects on electron dynamics: (i) coupled electron-nuclear motion and (ii) nuclear spatial delocalization as a result of the zero-point energy in the neutral molecule. Within the Ehrenfest approximation, our calculations show that the coherent electron dynamics in these molecules is not lost as a result of coupled electron-nuclear motion. In contrast, as a result of nuclear spatial delocalization, dephasing of the oscillations occurs on a time scale of only a few fs, long before any significant nuclear motion can occur. The results have been rationalized using a semi-quantitative model based upon the gradients of the potential energy surfaces. PMID:26979684

  8. New concept for a toxicity assay based on multiple indexes from the wave shape of damped metabolic oscillation induced in living yeast cells (part II): application to analytical toxicology.

    PubMed

    Nakamura, H; Suzuki, M

    2007-10-01

    An ideal toxicity assay should utilize multiple indexes obtained from transient changes of metabolic activities. Here, we demonstrate the possibility for a novel toxicity bioassay using the damped glycolytic oscillation phenomenon occurring in starved yeast cells. In a previous study, the phenomenon was characterized in detail. Under optimum conditions to induce the phenomenon, the wave shapes of the damped glycolytic oscillations were changed by the instantaneous addition of both glucose and chemicals and by changing the chemical concentration. We estimated the changes in the oscillation wave shapes as six indexes, i.e., the number of wave cycles, maximum amplitude, oscillation frequency, attenuation coefficient, initial peak height, and non-steady-state time. These index changes were obtained from several kinds of chemicals. The chemicals, especially those for acids (0.01-100 mM HCl and 0.01-50 mM citric acid), bases (0.001-50 mM KOH), heavy metal ions (1-1,000 mg L(-1); Cu(2+), Pb(2+), Cd(2+), Hg(2+)), respiratory inhibitors (3-500 mg L(-1) NaN(3)), dissolved oxygen removers (10-300 mg L(-1) NaSO(3)), surfactants (10-200 mg L(-1) benzalkonium chloride), and aldehyde (10-1,000 mg L(-1) acetaldehyde), showed characteristic patterns depending on each chemical and its concentration. These significant results demonstrate the possibilities of new methods for both toxicity qualification and quantification. PMID:17717646

  9. Deficiencies in lamin B1 and lamin B2 cause neurodevelopmental defects and distinct nuclear shape abnormalities in neurons

    PubMed Central

    Coffinier, Catherine; Jung, Hea-Jin; Nobumori, Chika; Chang, Sandy; Tu, Yiping; Barnes, Richard H.; Yoshinaga, Yuko; de Jong, Pieter J.; Vergnes, Laurent; Reue, Karen; Fong, Loren G.; Young, Stephen G.

    2011-01-01

    Neuronal migration is essential for the development of the mammalian brain. Here, we document severe defects in neuronal migration and reduced numbers of neurons in lamin B1–deficient mice. Lamin B1 deficiency resulted in striking abnormalities in the nuclear shape of cortical neurons; many neurons contained a solitary nuclear bleb and exhibited an asymmetric distribution of lamin B2. In contrast, lamin B2 deficiency led to increased numbers of neurons with elongated nuclei. We used conditional alleles for Lmnb1 and Lmnb2 to create forebrain-specific knockout mice. The forebrain-specific Lmnb1- and Lmnb2-knockout models had a small forebrain with disorganized layering of neurons and nuclear shape abnormalities, similar to abnormalities identified in the conventional knockout mice. A more severe phenotype, complete atrophy of the cortex, was observed in forebrain-specific Lmnb1/Lmnb2 double-knockout mice. This study demonstrates that both lamin B1 and lamin B2 are essential for brain development, with lamin B1 being required for the integrity of the nuclear lamina, and lamin B2 being important for resistance to nuclear elongation in neurons. PMID:21976703

  10. High-frequency, correlated nuclear and electron oscillations in molecules in intense laser fields

    NASA Astrophysics Data System (ADS)

    Bandrauk, André D.; Chelkowski, Szczepan; Lu, Huizhong

    2013-03-01

    We have solved numerically the time-dependent Schrödinger equation (TDSE) describing dissociative-ionization of a H2 (and of a D2) molecule exposed to intense short-pulse laser light in one dimension. From the time dependent wave function we calculated the total average acceleration of the two electrons and the relative proton acceleration and the average of internuclear distance. We find that the general shape of the power spectra of electron and proton motion is very similar except that for the electrons the peaks occur at odd harmonics whereas for protons the peaks occur at even harmonics. We relate this to the appearance of higher order polarizabilities. The wavelet time-frequency analysis shows that, surprisingly, time profiles of electron and proton accelerations are nearly identical for high order harmonics. The wavelet time profiles confirm predictions of the three-step quasi-classical model of harmonic generation by identifying several (up to three) electron return times with high precision.

  11. Solar Oscillations

    NASA Technical Reports Server (NTRS)

    Duvall, Thomas

    2004-01-01

    Oscillations were first detected in the solar photosphere in 1962 by Leighton and students. In 1970 it was calculated that these oscillations, with a period near five minutes, were the manifestations of acoustic waves trapped in the interior. The subsequent measurements of the frequencies of global oscillation modes from the spatio-temporal power spectrum of the waves made possible the refinement of solar interior models. Over the years, increased understanding of the nuclear reaction rates, the opacity, the equation of state, convection, and gravitational settling have resulted. Mass flows shift the frequencies of modes leading to very accurate measurements of the interior rotation as a function of radius and latitude. In recent years, analogues of terrestrial seismology have led to a tomography of the interior, including measurements of global north-south flows and flow and wave speed measurements below features such as sunspots. The future of helioseismology seems bright with the approval of NASA's Solar Dynamics Observatory mission, to be launched in 2008.

  12. Ionization oscillations in Hall accelerators

    NASA Astrophysics Data System (ADS)

    Barral, S.; Peradzyński, Z.

    2010-01-01

    The underlying mechanism of low-frequency oscillations in Hall accelerators is investigated theoretically. It is shown that relaxation oscillations arise from a competition between avalanche ionization and the advective transport of the working gas. The model derived recovers the slow progression and fast recession of the ionization front. Analytical approximations of the shape of current pulses and of the oscillation frequency are provided for the case of large amplitude oscillations.

  13. Scleronomic Holonomic Constraints and Conservative Nonlinear Oscillators

    ERIC Educational Resources Information Center

    Munoz, R.; Gonzalez-Garcia, G.; Izquierdo-De La Cruz, E.; Fernandez-Anaya, G.

    2011-01-01

    A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present…

  14. Communication: Oscillating charge migration between lone pairs persists without significant interaction with nuclear motion in the glycine and Gly-Gly-NH-CH{sub 3} radical cations

    SciTech Connect

    Vacher, Morgane; Bearpark, Michael J.; Robb, Michael A.

    2014-05-28

    Coupled electron-nuclear dynamics has been studied, using the Ehrenfest method, for four conformations of the glycine molecule and a single conformation of Gly-Gly-NH-CH{sub 3}. The initial electronic wavepacket was a superposition of eigenstates corresponding to ionization from the σ lone pairs associated with the carbonyl oxygens and the amine nitrogen. For glycine, oscillating charge migration (when the nuclei were frozen) was observed for the 4 conformers studied with periods ranging from 2 to 5 fs, depending on the energy gap between the lone pair cationic states. When coupled nuclear motion was allowed (which was mainly NH{sub 2} partial inversion), the oscillations hardly changed. For Gly-Gly-NH-CH{sub 3}, charge migration between the carbonyl oxygens and the NH{sub 2} lone pair can be observed with a period similar to glycine itself, also without interaction with nuclear motion. These simulations suggest that charge migration between lone pairs can occur independently of the nuclear motion.

  15. Effective pairing interaction in semi-infinite nuclear matter in the Brueckner approach: Model {delta}-shaped NN interaction

    SciTech Connect

    Baldo, M.; Lombardo, U.; Saperstein, E.E.; Zverev, M.V.

    1995-09-01

    The problem of pairing in semi-infinite nuclear matter is considered in the Brueckner approach. Equations for effective pairing interaction in semi-infinite matter are derived for the case of the separable representation of realistic NN interaction. The propagator of two noninteracting particles in a semi-infinite potential well is calculated numerically. The equation for effective interaction is solved for a model 8-shaped NN interaction, which correctly reproduces NN scattering in the low-energy limit. 15 refs., 10 figs.

  16. Nuclear shape transitions and some properties of aligned-particle configurations at high spin

    SciTech Connect

    Koo, T.L.; Chowdhury, P.; Emling, H.

    1982-01-01

    Two topics are addressed in this paper. First, we discuss the variation of shapes with spin and neutron number for nuclei in the N approx. = 88 transitional region. Second, we present comments on the feeding times of very high spin single-particle yrast states.

  17. Oscillator detector

    SciTech Connect

    Potter, B.M.

    1980-05-13

    An alien liquid detector employs a monitoring element and an oscillatory electronic circuit for maintaining the temperature of the monitoring element substantially above ambient temperature. The output wave form, eg., frequency of oscillation or wave shape, of the oscillatory circuit depends upon the temperaturedependent electrical characteristic of the monitoring element. A predetermined change in the output waveform allows water to be discriminated from another liquid, eg., oil. Features of the invention employing two thermistors in two oscillatory circuits include positioning one thermistor for contact with water and the other thermistor above the oil-water interface to detect a layer of oil if present. Unique oscillatory circuit arrangements are shown that achieve effective thermistor action with an economy of parts and energizing power. These include an operational amplifier employed in an astable multivibrator circuit, a discrete transistor-powered tank circuit, and use of an integrated circuit chip.

  18. Novel plant SUN–KASH bridges are involved in RanGAP anchoring and nuclear shape determination

    PubMed Central

    Zhou, Xiao; Graumann, Katja; Evans, David E.

    2012-01-01

    Inner nuclear membrane Sad1/UNC-84 (SUN) proteins interact with outer nuclear membrane (ONM) Klarsicht/ANC-1/Syne homology (KASH) proteins, forming linkers of nucleoskeleton to cytoskeleton conserved from yeast to human and involved in positioning of nuclei and chromosomes. Defects in SUN–KASH bridges are linked to muscular dystrophy, progeria, and cancer. SUN proteins were recently identified in plants, but their ONM KASH partners are unknown. Arabidopsis WPP domain–interacting proteins (AtWIPs) are plant-specific ONM proteins that redundantly anchor Arabidopsis RanGTPase–activating protein 1 (AtRanGAP1) to the nuclear envelope (NE). In this paper, we report that AtWIPs are plant-specific KASH proteins interacting with Arabidopsis SUN proteins (AtSUNs). The interaction is required for both AtWIP1 and AtRanGAP1 NE localization. AtWIPs and AtSUNs are necessary for maintaining the elongated nuclear shape of Arabidopsis epidermal cells. Together, our data identify the first KASH members in the plant kingdom and provide a novel function of SUN–KASH complexes, suggesting that a functionally diverged SUN–KASH bridge is conserved beyond the opisthokonts. PMID:22270916

  19. Current oscillations in nanopores

    NASA Astrophysics Data System (ADS)

    Hyland, Brittany

    We develop a simple phenomenological model to describe current oscillations in single, conically shaped nanopores. The model utilizes aspects of reaction rate theory, electrochemical oscillators, and nonlinear dynamical systems. Time series of experimental data were analyzed and compared to time series simulated using the model equations. There is good qualitative agreement between experiment and simulation, though the model needs to be improved in order to obtain better quantitative agreement.

  20. Construction of Nuclear Envelope Shape by a High-Genus Vesicle with Pore-Size Constraint.

    PubMed

    Noguchi, Hiroshi

    2016-08-23

    Nuclear pores have an approximately uniform distribution in the nuclear envelope of most living cells. Hence, the morphology of the nuclear envelope is a spherical stomatocyte with a high genus. We have investigated the morphology of high-genus vesicles under pore-size constraint using dynamically triangulated membrane simulations. Bending-energy minimization without volume or other constraints produces a circular-cage stomatocyte, where the pores are aligned in a circular line on an oblate bud. As the pore radius is reduced, the circular-pore alignment is more stabilized than a random pore distribution on a spherical bud. However, we have clarified the conditions for the formation of a spherical stomatocyte: a small perinuclear volume, osmotic pressure within nucleoplasm, and repulsion between the pores. When area-difference elasticity is taken into account, the formation of cylindrical or budded tubules from the stomatocyte and discoidal stomatocyte is found. PMID:27558725

  1. X-Ray Comb Generation from Nuclear-Resonance-Stabilized X-Ray Free-Electron Laser Oscillator for Fundamental Physics and Precision Metrology

    SciTech Connect

    Adams, B. W.; Kim, K. -J.

    2015-03-31

    An x-ray free-electron laser oscillator (XFELO) is a next-generation x-ray source, similar to free-electron laser oscillators at VUV and longer wavelengths but using crystals as high-reflectivity x-ray mirrors. Each output pulse from an XFELO is fully coherent with high spectral purity. The temporal coherence length can further be increased drastically, from picoseconds to microseconds or even longer, by phase-locking successive XFELO output pulses, using the narrow nuclear resonance lines of nuclei such as Fe-57 as a reference. We show that the phase fluctuation due to the seismic activities is controllable and that due to spontaneous emission is small. The fluctuation of electron-bunch spacing contributes mainly to the envelope fluctuation but not to the phase fluctuation. By counting the number of standing-wave maxima formed by the output of the nuclear-resonance-stabilized (NRS) XFELO over an optically known length, the wavelength of the nuclear resonance can be accurately measured, possibly leading to a new length or frequency standard at x-ray wavelengths. A NRS-XFELO will be an ideal source for experimental x-ray quantum optics as well as other fundamental physics. The technique can be refined for other, narrower resonances such as Ta-181 or Sc-45.

  2. Switchable dual-pulse-shape mode-locked figure-eight all-PM fibre master oscillator with 0.5 W-level average output

    NASA Astrophysics Data System (ADS)

    Kobtsev, Sergey; Ivanenko, Aleksey; Fedotov, Yurii; Smirnov, Sergey V.; Golubtsov, Artur; Khripunov, Sergey

    2016-03-01

    For the first time a method for switching between generation of single- and double-scale pulses has been demonstrated in a mode-locked figure-eight NALM-based all-PM-fibre Yb master oscillator by adjustment of two pumps power. Introduction into a F8 configuration of a non-linear amplifying loop mirror with two active media not only ensured relatively high average output power of the master oscillator (> 0.5 W at 22-MHz repetition rate), but also allowed switching laser operation from one pulse type (single-scale with duration of <10 ps) to another - femtosecond clusters with envelope width of 16 ps and sub-pulse duration <200 fs.

  3. Hutchinson-Gilford progeria syndrome alters nuclear shape and reduces cell motility in three dimensional model substrates.

    PubMed

    Booth-Gauthier, Elizabeth A; Du, Vicard; Ghibaudo, Marion; Rape, Andrew D; Dahl, Kris Noel; Ladoux, Benoit

    2013-03-01

    Cell migration through tight interstitial spaces in three dimensional (3D) environments impacts development, wound healing and cancer metastasis and is altered by the aging process. The stiffness of the extracellular matrix (ECM) increases with aging and affects the cells and cytoskeletal processes involved in cell migration. However, the nucleus, which is the largest and densest organelle, has not been widely studied during cell migration through the ECM. Additionally, the nucleus is stiffened during the aging process through the accumulation of a mutant nucleoskeleton protein lamin A, progerin. By using microfabricated substrates to mimic the confined environment of surrounding tissues, we characterized nuclear movements and deformation during cell migration into micropillars where interspacing can be tuned to vary nuclear confinement. Cell motility decreased with decreased micropillar (μP) spacing and correlated with increased dysmorphic shapes of nuclei. We examined the effects of increased nuclear stiffness which correlates with cellular aging by studying Hutchinson-Gilford progeria syndrome cells which are known to accumulate progerin. With the expression of progerin, cells showed a threshold response to decreased μP spacing. Cells became trapped in the close spacing, possibly from visible micro-defects in the nucleoskeleton induced by cell crawling through the μP and from reduced force generation, measured independently. We suggest that ECM changes during aging could be compounded by the increasing stiffness of the nucleus and thus changes in cell migration through 3D tissues. PMID:23370891

  4. The role of lipid-activated nuclear receptors in shaping macrophage and dendritic cell function: From physiology to pathology.

    PubMed

    Kiss, Mate; Czimmerer, Zsolt; Nagy, Laszlo

    2013-08-01

    Nuclear receptors are ligand-activated transcription factors linking lipid signaling to the expression of the genome. There is increasing appreciation of the involvement of this receptor network in the metabolic programming of macrophages and dendritic cells (DCs), essential members of the innate immune system. In this review we focus on the role of retinoid X receptor, retinoic acid receptor, peroxisome proliferator-associated receptor γ, liver X receptor, and vitamin D receptor in shaping the immune and metabolic functions of macrophages and DCs. We also provide an overview of the contribution of macrophage- and DC-expressed nuclear receptors to various immunopathologic conditions, such as rheumatoid arthritis, inflammatory bowel disease, systemic lupus erythematosus, asthma, and some others. We suggest that systematic analyses of the roles of these receptors and their activating lipid ligands in immunopathologies combined with complementary and focused translational and clinical research will be crucial for the development of new therapies using the many molecules available to target nuclear receptors. PMID:23905916

  5. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    SciTech Connect

    Cao, H.

    2015-05-26

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0 to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (Nex) and ion pairs (Ni) and their ratio (Nex/Ni) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.

  6. Measurement of Scintillation and Ionization Yield and Scintillation Pulse Shape from Nuclear Recoils in Liquid Argon

    DOE PAGESBeta

    Cao, H.

    2015-05-26

    We have measured the scintillation and ionization yield of recoiling nuclei in liquid argon as a function of applied electric field by exposing a dual-phase liquid argon time projection chamber (LAr-TPC) to a low energy pulsed narrow band neutron beam produced at the Notre Dame Institute for Structure and Nuclear Astrophysics. Liquid scintillation counters were arranged to detect and identify neutrons scattered in the TPC and to select the energy of the recoiling nuclei. We also report measurements of the scintillation yields for nuclear recoils with energies from 10.3 to 57.3 keV and for median applied electric fields from 0more » to 970 V/cm. For the ionization yields, we report measurements from 16.9 to 57.3 keV and for electric fields from 96.4 to 486 V/cm. Furthermore, we report the observation of an anticorrelation between scintillation and ionization from nuclear recoils, which is similar to the anticorrelation between scintillation and ionization from electron recoils. Assuming that the energy loss partitions into excitons and ion pairs from 83mKr internal conversion electrons is comparable to that from 207Bi conversion electrons, we obtained the numbers of excitons (Nex) and ion pairs (Ni) and their ratio (Nex/Ni) produced by nuclear recoils from 16.9 to 57.3 keV. Motivated by arguments suggesting direction sensitivity in LAr-TPC signals due to columnar recombination, a comparison of the light and charge yield of recoils parallel and perpendicular to the applied electric field is presented for the first time.« less

  7. Fractional oscillator.

    PubMed

    Stanislavsky, A A

    2004-11-01

    We consider a fractional oscillator which is a generalization of the conventional linear oscillator in the framework of fractional calculus. It is interpreted as an ensemble average of ordinary harmonic oscillators governed by a stochastic time arrow. The intrinsic absorption of the fractional oscillator results from the full contribution of the harmonic oscillator ensemble: these oscillators differ a little from each other in frequency so that each response is compensated by an antiphase response of another harmonic oscillator. This allows one to draw a parallel in the dispersion analysis for media described by a fractional oscillator and an ensemble of ordinary harmonic oscillators with damping. The features of this analysis are discussed. PMID:15600586

  8. Laterally oscillating nitinol engine

    SciTech Connect

    Banks, R.

    1987-09-08

    This patent describes a laterally oscillating nitinol engine comprising: a first L-shaped drive member journalled for pivoting horizontal oscillation about the juncture of the legs of the L-shaped member, a second drive member journalled for pivoting about a point proximate the outboard end of the shorter leg of the L-shaped member at a distance from the pivot journal of the L-shaped member, a bearing block secured to the end of longer leg of the L-shaped and having a guide hole. The second member extending through the guide hole and arranged to reciprocate therein, a shape memory alloy power element disposed in flexure secured at its ends to the bearing block and to the second member intermediate the sliding connection with the bearing block and the pivotal connection of the second member, means for disposing different temperature baths below the element whereby as the drive members oscillate about their journals the element alternately dips into one bath and then the other, and means for absorbing a portion of the energy developed by the engine and moving the power element from the cold bath to the hot bath.

  9. Nonlinear oscillations of coalescing magnetic flux ropes.

    PubMed

    Kolotkov, Dmitrii Y; Nakariakov, Valery M; Rowlands, George

    2016-05-01

    An analytical model of highly nonlinear oscillations occurring during a coalescence of two magnetic flux ropes, based upon two-fluid hydrodynamics, is developed. The model accounts for the effect of electric charge separation, and describes perpendicular oscillations of the current sheet formed by the coalescence. The oscillation period is determined by the current sheet thickness, the plasma parameter β, and the oscillation amplitude. The oscillation periods are typically greater or about the ion plasma oscillation period. In the nonlinear regime, the oscillations of the ion and electron concentrations have a shape of a narrow symmetric spikes. PMID:27300993

  10. U(5)-SU(3) nuclear shape transition within the interacting boson model applied to dysprosium isotopes

    NASA Astrophysics Data System (ADS)

    Kotb, M.

    2016-07-01

    In the framework of the interacting boson model (IBM) with intrinsic coherent state, the shape Hamiltonian from spherical vibrator U(5) to axially symmetric prolate deformed rotator SU(3) are examined. The Hamiltonian used is composed of a single boson energy term and quadrupole term. The potential energy surfaces (PES' s) corresponding to the U(5)-SU(3) transition are calculated with variation of a scaling and control parameters. The model is applied to 150-162Dy chain of isotopes. In this chain a change from spherical to well deformed nuclei is observed when moving from the lighter to heavier isotopes. 156Dy is a good candidate for the critical point symmetry X(5). The parameters of the model are determined by using a computer simulated search program in order to minimize the deviation between our calculated and some selected experimental energy levels, B(E2) transition rates and the two neutron separation energies S2n. We have also studied the energy ratios and the B(E2) values for the yrast state of the critical nucleus. The nucleon pair transfer intensities between ground-ground and ground-beta states are examined within IBM and boson intrinsic coherent framework.

  11. Evolution of ground state nuclear shapes in tungsten nuclei in terms of interacting boson model

    NASA Astrophysics Data System (ADS)

    Khalaf, A. M.; El-Shal, A. O.; Taha, M. M.; El-Sayed, M. A.

    2016-03-01

    The tungsten nuclei 180-190W are investigated within the framework of the interacting boson model using an intrinsic coherent state formalism. The Hamiltonian operator contains only multipole operators of the subalgebra associated with the dynamical symmetries SU(3) and O(6). The study includes the behavior of potential energy surfaces (BES's) and critical points in the space of the model parameters to declare the geometric character of the tungsten isotopic chain. Some selected energy levels and reduced E2 transition probabilities B(E2) for each nucleus are calculated to adjust the model parameters by using a computer code PH INT and simulated computer fitting programme to fit the experimental data with the IBM calculation by minimizing the root mean square deviations. The 180-190W isotopes lies in shape transition SU(3)-O(6) region of the IBM such that the lighter isotopes comes very clare to the SU(3) limit, while the behavior ones tend to be near the γ-unstable O(6) limit.

  12. Probing nuclear shapes close to the fission limit with the giant dipole resonance in {sup 216}Rn

    SciTech Connect

    Kmiecik, M.; Maj, A.; Brekiesz, M.; Krolas, W.; Meczynski, W.; Styczen, J.; Zieblinski, M.; Million, B.; Bracco, A.; Camera, F.; Benzoni, G.; Leoni, S.; Wieland, O.; Brambilla, S.; Herskind, B.; Kicinska-Habior, M.; Dubray, N.; Dudek, J.; Schunck, N.

    2004-12-01

    The gamma-ray decay of the giant dipole resonance (GDR) in the compound nucleus {sup 216}Rn formed with the reaction {sup 18}O+{sup 198}Pt at the bombarding energy of 96 MeV was investigated. High-energy gamma-ray spectra in coincidence with both prompt and delayed low-energy transitions were measured. The obtained GDR width at the average temperature {approx_equal}1 MeV was found to be larger than that at T=0 MeV and to be approximately constant as a function of spin. The measured width value of 7 MeV is found to be consistent with the predictions based on calculations of the nuclear shape distribution using the newest approach for the treatment of the fission barrier within the liquid drop model. The present study is the first investigation of the giant dipole resonance width from the fusion-evaporation decay channel in this nuclear mass range.

  13. Empirical formula of crustal torsional oscillations

    NASA Astrophysics Data System (ADS)

    Sotani, Hajime

    2016-02-01

    Crustal torsional oscillations depend on not only crust properties but also the stellar mass and radius. Thus, one could extract stellar information by identifying the observed frequencies of stellar oscillations with the crustal torsional oscillations. Owing to the confinement of torsional oscillations inside the crust region of neutron stars, we successfully derive an empirical formula for the fundamental crustal torsional oscillations as a function of the stellar mass, radius, the so-called slope parameter of the nuclear symmetry energy, and the angular index of oscillations, with which one can estimate the frequencies with high accuracy. This empirical formula could be valuable in both the astrophysics and nuclear physics communities.

  14. Exact Solutions of Schrödinger Equation with Improved Ring-Shaped Non-Spherical Harmonic Oscillator and Coulomb Potential

    NASA Astrophysics Data System (ADS)

    Ndem Ikot, Akpan; Akpan, Ita O.; Abbey, T. M.; Hassanabadi, Hassan

    2016-05-01

    We propose improved ring shaped like potential of the form, V(r, θ) = V(r) + (ħ2/2Mr2)[(β sin2 θ + γ cos2 θ + λ) / sin θ cos θ]2 and its exact solutions are presented via the Nikiforov–Uvarov method. The angle dependent part V(θ) = (ħ2 / 2 Mr2)[(β sin2 θ + γ cos2 θ + λ) / sin θ cos θ]2, which is reported for the first time embodied the novel angle dependent (NAD) potential and harmonic novel angle dependent potential (HNAD) as special cases. We discuss in detail the effects of the improved ring shaped like potential on the radial parts of the spherical harmonic and Coulomb potentials.

  15. Hybrid Reactor Simulation of Boiling Water Reactor Power Oscillations

    SciTech Connect

    Huang Zhengyu; Edwards, Robert M.

    2003-08-15

    Hybrid reactor simulation (HRS) of boiling water reactor (BWR) instabilities, including in-phase and out-of-phase (OOP) oscillations, has been implemented on The Pennsylvania State University TRIGA reactor. The TRIGA reactor's power response is used to simulate reactor neutron dynamics for in-phase oscillation or the fundamental mode of the reactor modal kinetics for OOP oscillations. The reactor power signal drives a real-time boiling channel simulation, and the calculated reactivity feedback is in turn fed into the TRIGA reactor via an experimental changeable reactivity device. The thermal-hydraulic dynamics, together with first harmonic mode power dynamics, is digitally simulated in the real-time environment. The real-time digital simulation of boiling channel thermal hydraulics is performed by solving constitutive equations for different regions in the channel and is realized by a high-performance personal computer. The nonlinearity of the thermal-hydraulic model ensures the capability to simulate the oscillation phenomena, limit cycle and OOP oscillation, in BWR nuclear power plants. By adjusting reactivity feedback gains for both modes, various oscillation combinations can be realized in the experiment. The dynamics of axially lumped power distribution over the core is displayed in three-dimensional graphs. The HRS reactor power response mimics the BWR core-wide power stability phenomena. In the OOP oscillation HRS, the combination of reactor response and the simulated first harmonic power using shaping functions mimics BWR regional power oscillations. With this HRS testbed, a monitoring and/or control system designed for BWR power oscillations can be experimentally tested and verified.

  16. Neurodynamic oscillators

    NASA Technical Reports Server (NTRS)

    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.

  17. Effects of heat input on the microstructure and toughness of the 8 MnMoNi 5 5 shape-welded nuclear steel

    NASA Astrophysics Data System (ADS)

    Million, Karl; Datta, Ratan; Zimmermann, Horst

    2005-04-01

    A weld metal well proven in the German nuclear industry served as the basis for the certification of a shape-welded steel to be used as base material for manufacture of nuclear primary components. The outstanding properties of this steel are attributed to the extremely fine-grained and stable primary microstructure. Subsequent reheating cycles caused by neighbouring weld beads do neither lead to coarsened brittle structures in the heat-affected zone nor to increase in hardness and decrease in toughness, as is the case with wrought steel materials. One of the largest new reactor vessel design amongst today's advanced reactor projects is considered to be particularly suitable for the use of shape-welded parts in place of forgings. In addition the need for design and development of new shape-welded steel grades for other new generation reactor projects is emphasized, in which the experience gained with this research could make a contribution.

  18. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

    PubMed Central

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-01-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

  19. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation.

    PubMed

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-01-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors' knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability. PMID:27080134

  20. A multiple-shape memory polymer-metal composite actuator capable of programmable control, creating complex 3D motion of bending, twisting, and oscillation

    NASA Astrophysics Data System (ADS)

    Shen, Qi; Trabia, Sarah; Stalbaum, Tyler; Palmre, Viljar; Kim, Kwang; Oh, Il-Kwon

    2016-04-01

    Development of biomimetic actuators has been an essential motivation in the study of smart materials. However, few materials are capable of controlling complex twisting and bending deformations simultaneously or separately using a dynamic control system. Here, we report an ionic polymer-metal composite actuator having multiple-shape memory effect, and is able to perform complex motion by two external inputs, electrical and thermal. Prior to the development of this type of actuator, this capability only could be realized with existing actuator technologies by using multiple actuators or another robotic system. This paper introduces a soft multiple-shape-memory polymer-metal composite (MSMPMC) actuator having multiple degrees-of-freedom that demonstrates high maneuverability when controlled by two external inputs, electrical and thermal. These multiple inputs allow for complex motions that are routine in nature, but that would be otherwise difficult to obtain with a single actuator. To the best of the authors’ knowledge, this MSMPMC actuator is the first solitary actuator capable of multiple-input control and the resulting deformability and maneuverability.

  1. Plant nuclear shape is independently determined by the SUN-WIP-WIT2-myosin XI-i complex and CRWN1

    PubMed Central

    Zhou, Xiao; Groves, Norman Reid; Meier, Iris

    2015-01-01

    Nuclei undergo dynamic shape changes during plant development, but the mechanism is unclear. In Arabidopsis, Sad1/UNC-84 (SUN) proteins, WPP domain-interacting proteins (WIPs), WPP domain-interacting tail-anchored proteins (WITs), myosin XI-i, and CROWDED NUCLEI 1 (CRWN1) have been shown to be essential for nuclear elongation in various epidermal cell types. It has been proposed that WITs serve as adaptors linking myosin XI-i to the SUN-WIP complex at the nuclear envelope (NE). Recently, an interaction between Arabidopsis SUN1 and SUN2 proteins and CRWN1, a plant analog of lamins, has been reported. Therefore, the CRWN1-SUN-WIP-WIT-myosin XI-i interaction may form a linker of the nucleoskeleton to the cytoskeleton complex. In this study, we investigate this proposed mechanism in detail for nuclei of Arabidopsis root hairs and trichomes. We show that WIT2, but not WIT1, plays an essential role in nuclear shape determination by recruiting myosin XI-i to the SUN-WIP NE bridges. Compared with SUN2, SUN1 plays a predominant role in nuclear shape. The NE localization of SUN1, SUN2, WIP1, and a truncated WIT2 does not depend on CRWN1. While crwn1 mutant nuclei are smooth, the nuclei of sun or wit mutants are invaginated, similar to the reported myosin XI-i mutant phenotype. Together, this indicates that the roles of the respective WIT and SUN paralogs have diverged in trichomes and root hairs, and that the SUN-WIP-WIT2-myosin XI-i complex and CRWN1 independently determine elongated nuclear shape. This supports a model of nuclei being shaped both by cytoplasmic forces transferred to the NE and by nucleoplasmic filaments formed under the NE. PMID:25759303

  2. Galactic oscillations

    NASA Technical Reports Server (NTRS)

    Miller, R. H.

    1991-01-01

    Long-lived oscillations that act like normal modes are described. The total kinetic energy is found to vary with time by amounts far in excess of the fluctuations expected from the virial theorem, and the variation shows periodic patterns that suggest oscillations. Experimental results indicate that oscillation amplitudes depend on the nature of the model. It is noted that it is difficult to answer questions about likely amplitudes in real galaxies with any confidence at the present time.

  3. Flat coil-based tunnel diode oscillator enabling to detect the real shape of the superconductive transition curve and capable of imaging the properties of HTSC films with high spatial resolution

    NASA Astrophysics Data System (ADS)

    Gevorgyan, Samvel; Shirinyan, Hovsep; Manukyan, Artashes; Sharoyan, Eduard; Takeo, Masakatsu; Polyanskii, Anatolii; Sarkisyan, Albert; Matsushita, Teruo

    2004-03-01

    Owing to a pick-up coil's flat design, relatively low MHz-range operation frequency, and six orders relative resolution a flat coil-based tunnel diode oscillator has advantages, compared to all other methods. They become crucial in studies with thin high-Tc superconductivity (HTSC) materials (with small signals), especially at the start of the Cooper pairs' formation. Due to this the superconductivity precursor ‘paramagnetic' effect was detected recently in YBaCuO films at N/S transition. It precedes Meissner ejection and specifies details of the shape of the transition curve. We discuss the influence of the currents on this effect, and the relationship between the quality of the material and the shape of the effect. A new imaging device has also been created based on this test method (using a focused He-Ne laser beam as a probing signal), capable of imaging the properties of HTSC films with ∼3 μm spatial resolution. The method is based on detection of the inductance and Q-factor value changes of a single-layer flat coil, placed at the face of the sample. This leads to frequency and/or amplitude changes of the stable oscillator. The test device enabled 2D-mapping of the grain structure of a bridge-shaped YBaCuO film. Basically, the method is capable of imaging 2D-current distribution in thin HTS with sub-μm spatial-resolution, using non-bolometric response. However, the achieved resolution ∼3 μm of a bolometric nature (in a given device with 3.5 mm-size coil) by no means is limited by the abilities of the method, but mainly, it depends on how narrowly it is possible to focus the probing beam, while the own resolution of a present flat coil-based technique is better than 0.1 μm, and can be improved essentially by reducing the coil size.

  4. Calcium Oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent; Bird, Gary S.; Putney, James W.

    2011-01-01

    Calcium signaling results from a complex interplay between activation and inactivation of intracellular and extracellular calcium permeable channels. This complexity is obvious from the pattern of calcium signals observed with modest, physiological concentrations of calcium-mobilizing agonists, which typically present as sequential regenerative discharges of stored calcium, a process referred to as calcium oscillations. In this review, we discuss recent advances in understanding the underlying mechanism of calcium oscillations through the power of mathematical modeling. We also summarize recent findings on the role of calcium entry through store-operated channels in sustaining calcium oscillations and in the mechanism by which calcium oscillations couple to downstream effectors. PMID:21421924

  5. Effects of Recent Reactor Anti-neutrino Spectra on Neutrino Oscillations

    NASA Astrophysics Data System (ADS)

    Sterbenz, Ciara

    2015-10-01

    The β-decay of nuclear fission fragments produces a very large ve flux from nuclear reactions. The shape of the expected flux has previously been predicted by converting the measured β-electron spectrum to an ve spectrum. Recent reactor neutrino experiments, however, find a large shoulder in the observed ve spectrum relative to this prediction in the energy region 5 - 7 MeV. Accurate knowledge of the expected ve flux from reactors is important for oscillation experiments that only involve one neutrino detector. In this project, I examine the implications of these spectral changes on the ν oscillation result found by the KamLAND experiment. At the time of their finding, the spectral anomaly from 5 - 7 MeV had not be observed. I have re-derived the oscillation parameters Δm2 and sin2 (2 θ) using the anti-neutrino flux from Daya Bay and from nuclear database predictions. With these new expected fluxes, these oscillation parameters shifted and their uncertainties increased. I compare the new oscillation parameters with those derived from solar neutrino oscillation data.

  6. Microelectronic oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1969-01-01

    Bipolar transistor operated in a grounded base configuration is used as the inductor in a microelectronic oscillator. This configuration is employed using thin-film hybrid technology and is also applicable to monolithic technology.

  7. Power oscillator

    DOEpatents

    Gitsevich, Aleksandr

    2001-01-01

    An oscillator includes an amplifier having an input and an output, and an impedance transformation network connected between the input of the amplifier and the output of the amplifier, wherein the impedance transformation network is configured to provide suitable positive feedback from the output of the amplifier to the input of the amplifier to initiate and sustain an oscillating condition, and wherein the impedance transformation network is configured to protect the input of the amplifier from a destructive feedback signal. One example of the oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  8. Interaction function of oscillating coupled neurons

    PubMed Central

    Dodla, Ramana; Wilson, Charles J.

    2013-01-01

    Large scale simulations of electrically coupled neuronal oscillators often employ the phase coupled oscillator paradigm to understand and predict network behavior. We study the nature of the interaction between such coupled oscillators using weakly coupled oscillator theory. By employing piecewise linear approximations for phase response curves and voltage time courses, and parameterizing their shapes, we compute the interaction function for all such possible shapes and express it in terms of discrete Fourier modes. We find that reasonably good approximation is achieved with four Fourier modes that comprise of both sine and cosine terms. PMID:24229210

  9. Application of the double relaxation oscillation superconducting quantum interference device sensor to micro-tesla 1H nuclear magnetic resonance experiments

    NASA Astrophysics Data System (ADS)

    Kang, Chan Seok; Kim, Kiwoong; Lee, Seong-Joo; Hwang, Seong-min; Kim, Jin-Mok; Yu, Kwon Kyu; Kwon, Hyukchan; Lee, Sang Kil; Lee, Yong-Ho

    2011-09-01

    We developed an ultra-low field (ULF)-nuclear magnetic resonance (NMR) measurement system capable of working with a measurement field (Bm) of several micro-tesla and performed basic NMR studies with a double relaxation oscillation superconducting quantum interference device (DROS) instead of conventional dc-SQUIDs. DROS is a SQUID sensor utilizing a relaxation oscillation between a dc-SQUID and a relaxation circuit; the new unit consists of an inductor and a resistor, and is connected in parallel with the SQUID. DROS has a 10 times larger flux-to-voltage transfer coefficient (˜mV/ϕ0) than that of the dc-SQUID, and this large transfer coefficient enables the acquisition of the SQUID signal with a simple flux-locked-loop (FLL) circuit using room temperature pre-amplifiers. The DROS second-order gradiometer showed average field noise of 9.2 μϕ0/√Hz in a magnetically shielded room (MSR). In addition, a current limiter formed of a Josephson junction array was put in a flux-transformer of DROS to prevent excessive currents that can be generated from the high pre-polarization field (Bp). Using this system, we measured an 1H NMR signal in water under 2.8 μT Bm field and reconstructed a one-dimensional MR image from the 1H NMR signal under a gradient field BG of 4.09 nT/mm. In addition, we confirmed that the ULF-NMR system can measure the NMR signal in the presence of metal without any distortion by measuring the NMR signal of a sample wrapped with metal. Lastly, we have measured the scalar J-coupling of trimethylphosphate and were able to confirm a clear doublet NMR signal with the coupling strength J3[P,H] = 10.4 ± 0.8 Hz. Finally, because the existing ULF-NMR/MRI studies were almost all performed with dc-SQUID based systems, we constructed a dc-SQUID-based ULF-NMR system in addition to the DROS based system and compared the characteristics of the two different systems by operating the two systems under identical experimental conditions.

  10. Programmable Oscillator

    NASA Technical Reports Server (NTRS)

    Quirk, Kevin J.; Patawaran, Ferze D.; Nguyen, Danh H.; Lee, Clement G.; Nguyen, Huy

    2011-01-01

    A programmable oscillator is a frequency synthesizer with an output phase that tracks an arbitrary function. An offset, phase-locked loop circuit is used in combination with an error control feedback loop to precisely control the output phase of the oscillator. To down-convert the received signal, several stages of mixing may be employed with the compensation for the time-base distortion of the carrier occurring at any one of those stages. In the Goldstone Solar System Radar (GSSR), the compensation occurs in the mixing from an intermediate frequency (IF), whose value is dependent on the station and band, to a common IF used in the final stage of down-conversion to baseband. The programmable oscillator (PO) is used in the final stage of down-conversion to generate the IF, along with a time-varying phase component that matches the time-base distortion of the carrier, thus removing it from the final down-converted signal.

  11. Nuclear Aerosols: Direct Simulation and Elucidation of the Role of Multiple Components, Radioactivity, Charge, Shape and Spatial Inhomogeneity

    SciTech Connect

    Sudarshan K. Loyalka

    2008-10-12

    Nuclear aerosols can originate from severe core damae in light water reactors, core disruptive accidents in fast reactors, nuclear accidents during nuclear material transport, at waste disposal sites, or explosions. These aerosols evolve under natural transport processes as well as under the influence of engineered safety features. Such aerosols can be hazardous for the equipment inside the reactor, and when leaked into the environment, pose potential risks to the public. Hence, the origin, movement and distribution of these aerosols need to be studied and controlled.

  12. Effect of temperature on the shape of spatial quasi-periodic oscillations of the refractive index of alkali atoms in an optically dense medium with a closed excitation contour of Δ type

    SciTech Connect

    Barantsev, K A; Litvinov, A N

    2014-10-31

    A theory of a closed excitation contour (Δ system) of a three-level atom in an optically dense medium is constructed with allowance for temperature. The spatial quasi-periodic oscillations of the refractive index in the system under study are shown to damp with increasing temperature. The range of temperatures at which these oscillations are most pronounced is found. (quantum optics)

  13. Geometry of thermal plasma oscillations

    SciTech Connect

    Burton, Da; Noble, A.

    2009-01-22

    We develop a method for investigating the relationship between the shape of a 1-particle distribution and non-linear electrostatic oscillations in a collisionless plasma, incorporating transverse thermal motion. A general expression is found for the maximum sustainable electric field, and is evaluated for a particular highly anisotropic distribution.

  14. STABILIZED OSCILLATOR

    DOEpatents

    Jessen, P.L.; Price, H.J.

    1958-03-18

    This patent relates to sine-wave generators and in particular describes a generator with a novel feedback circuit resulting in improved frequency stability. The generator comprises two triodes having a common cathode circuit connected to oscillate at a frequency and amplitude at which the loop galn of the circutt ls unity, and another pair of triodes having a common cathode circuit arranged as a conventional amplifier. A signal is conducted from the osciliator through a frequency selective network to the amplifier and fed back to the osciliator. The unique feature of the feedback circuit is the amplifier operates in the nonlinear portion of its tube characteristics thereby providing a relatively constant feedback voltage to the oscillator irrespective of the amplitude of its input signal.

  15. Mito-nuclear genetic comparison in a Wolbachia infected weevil: insights on reproductive mode, infection age and evolutionary forces shaping genetic variation

    PubMed Central

    2010-01-01

    Background Maternally inherited endosymbionts like Wolbachia pipientis are in linkage disequilibrium with the mtDNA of their hosts. Therefore, they can induce selective sweeps, decreasing genetic diversity over many generations. This sex ratio distorter, that is involved in the origin of parthenogenesis and other reproductive alterations, infects the parthenogenetic weevil Naupactus cervinus, a serious pest of ornamental and fruit plants. Results Molecular evolution analyses of mitochondrial (COI) and nuclear (ITS1) sequences from 309 individuals of Naupactus cervinus sampled over a broad range of its geographical distribution were carried out. Our results demonstrate lack of recombination in the nuclear fragment, non-random association between nuclear and mitochondrial genomes and the consequent coevolution of both genomes, being an indirect evidence of apomixis. This weevil is infected by a single Wolbachia strain, which could have caused a moderate bottleneck in the invaded population which survived the initial infection. Conclusions Clonal reproduction and Wolbachia infection induce the coevolution of bacterial, mitochondrial and nuclear genomes. The time elapsed since the Wolbachia invasion would have erased the traces of the demographic crash in the mtDNA, being the nuclear genome the only one that retained the signal of the bottleneck. The amount of genetic change accumulated in the mtDNA and the high prevalence of Wolbachia in all populations of N. cervinus agree with the hypothesis of an ancient infection. Wolbachia probably had great influence in shaping the genetic diversity of N. cervinus. However, it would have not caused the extinction of males, since sexual and asexual infected lineages coexisted until recent times. PMID:21050430

  16. Dual Species NMR Oscillator

    NASA Astrophysics Data System (ADS)

    Weber, Joshua; Korver, Anna; Thrasher, Daniel; Walker, Thad

    2016-05-01

    We present progress towards a dual species nuclear magnetic oscillator using synchronous spin exchange optical pumping. By applying the bias field as a sequence of alkali 2 π pulses, we generate alkali polarization transverse to the bias field. The alkali polarization is then modulated at the noble gas resonance so that through spin exchange collisions the noble gas becomes polarized. This novel method of NMR suppresses the alkali field frequency shift by at least a factor of 2500 as compared to longitudinal NMR. We will present details of the apparatus and measurements of dual species co-magnetometry using this method. Research supported by the NSF and Northrop-Grumman Corp.

  17. The electrical soliton oscillator

    NASA Astrophysics Data System (ADS)

    Ricketts, David Shawn

    Solitons are a special class of pulse-shaped waves that propagate in nonlinear dispersive media while maintaining their spatial confinement. They are found throughout nature where the proper balance between nonlinearity and dispersion is achieved. Examples of the soliton phenomena include shallow water waves, vibrations in a nonlinear spring-mass lattice, acoustic waves in plasma, and optical pulses in fiber optic cable. In electronics, the nonlinear transmission line (NLTL) serves as a nonlinear dispersive medium that propagates voltage solitons. Electrical solitons on the NLTL have been actively investigated over the last 40 years, particularly in the microwave domain, for sharp pulse generation applications and for high-speed RF and microwave sampling applications. In these past studies the NLTL has been predominantly used as a 2-port system where a high-frequency input is required to generate a sharp soliton output through a transient process. One meaningful extension of the past 2-port NLTL works would be to construct a 1-port self-sustained electrical soliton oscillator by properly combining the NLTL with an amplifier (positive active feedback). Such an oscillator would self-start by growing from ambient noise to produce a train of periodic soliton pulses in steady-state, and hence would make a self-contained soliton generator not requiring an external high-frequency input. While such a circuit may offer a new direction in the field of electrical pulse generation, there has not been a robust electrical soliton oscillator reported to date to the best of our knowledge. In this thesis we introduce the first robust electrical soliton oscillator, which is able to self-generate a stable, periodic train of electrical solitons. This new oscillator is made possible by combining the NLTL with a unique nonlinear amplifier that is able to "tame" the unruly dynamics of the NLTL. The principle contribution of this thesis is the identification of the key instability

  18. Grid oscillators

    NASA Technical Reports Server (NTRS)

    Popovic, Zorana B.; Kim, Moonil; Rutledge, David B.

    1988-01-01

    Loading a two-dimensional grid with active devices offers a means of combining the power of solid-state oscillators in the microwave and millimeter-wave range. The grid structure allows a large number of negative resistance devices to be combined. This approach is attractive because the active devices do not require an external locking signal, and the combining is done in free space. In addition, the loaded grid is a planar structure amenable to monolithic integration. Measurements on a 25-MESFET grid at 9.7 GHz show power-combining and frequency-locking without an external locking signal, with an ERP of 37 W. Experimental far-field patterns agree with theoretical results obtained using reciprocity.

  19. Integration of the nuclear receptor REV-ERBα linked with circadian oscillators in the expressions of Alas1, Ppargc1a, and Il6 genes in rat granulosa cells.

    PubMed

    Chen, Huatao; Isayama, Keishiro; Kumazawa, Makoto; Zhao, Lijia; Yamauchi, Nobuhiko; Shigeyoshi, Yasufumi; Hashimoto, Seiichi; Hattori, Masa-aki

    2015-01-01

    The nuclear receptor REV-ERBα links circadian rhythms and numerous physiological processes, but its physiological role in ovaries remains largely unknown. The aim of this study was to determine the potential role of REV-ERBα in the regulation of the transcription of its putative target genes in granulosa cells (GCs) prepared from Per2-destablized luciferase (dLuc) reporter gene transgenic rats. Alas1, Ppargc1a, and Il6 were chosen as representatives for genes analysis. A real-time monitoring system of Per2 promoter activity was performed to detect Per2-dLuc circadian oscillations. Two agonists (GSK4112, heme) and an antagonist (SR8278) of REV-ERBα as well as Rev-erbα siRNA knockdown were used to identify its target genes. Clear Per2-dLuc circadian oscillations were generated in matured GCs after synchronization with GSK4112 or SR8278. GSK4112 treatment lengthened and SR8278 treatment shortened the period of circadian oscillations in matured GCs stimulated with or without luteinizing hormone (LH). GSK4112 showed an inhibitory effect on the amplitude of circadian oscillations and caused an arrhythmic expression of canonical clock genes. SR8278 also had a subtle effect on their daily expression profiles, but the treatment resulted only in the arrhythmic expression of Rev-erbα. These findings indicate the functional biological activity of REV-ERBα in response to its ligands. Its natural ligand heme further elongated the period of circadian oscillations and alleviated their amplitudes in GCs cultured with LH. Heme treatment also repressed the expressions of clock genes, Alas1, Il6, and Ppargc1a. Rev-erbα knockdown up-regulated these transcript levels. Collectively, these data extend the recent finding to rat GCs and demonstrate that REV-ERBα represses the expressions of Alas1, Ppargc1a, and Il6, providing novel insights into the physiological significance of REV-ERBα in ovarian circadian oscillators. PMID:26102301

  20. Min-protein oscillations in round bacteria

    NASA Astrophysics Data System (ADS)

    Huang, Kerwyn Casey; Wingreen, Ned S.

    2004-12-01

    In rod-shaped Escherichia coli cells, the Min proteins, which are involved in division-site selection, oscillate from pole-to-pole. The homologs of the Min proteins from the round bacterium Neisseria gonorrhoeae also form a spatial oscillator when expressed in wild-type and round, rodA- mutants of E. coli, suggesting that the Min proteins form an oscillator in N. gonorrhoeae. Here we report that a numerical model for Min-protein oscillations in rod-shaped cells also produces oscillations in round cells (cocci). Our numerical results explain why the MinE-protein rings found in wild-type E. coli are absent in round mutants. In addition, we find that for round cells there is a minimum radius below which oscillations do not occur, and a maximum radius above which oscillations become mislocalized. Finally, we demonstrate that Min-protein oscillations can select the long axis in nearly round cells based solely on geometry, a potentially important factor in division-plane selection in cocci.

  1. Analysis of Rattleback Chaotic Oscillations

    PubMed Central

    Stavrinides, Stavros G.; Banerjee, Santo

    2014-01-01

    Rattleback is a canoe-shaped object, already known from ancient times, exhibiting a nontrivial rotational behaviour. Although its shape looks symmetric, its kinematic behaviour seems to be asymmetric. When spun in one direction it normally rotates, but when it is spun in the other direction it stops rotating and oscillates until it finally starts rotating in the other direction. It has already been reported that those oscillations demonstrate chaotic characteristics. In this paper, rattleback's chaotic dynamics are studied by applying Kane's model for different sets of (experimentally decided) parameters, which correspond to three different experimental prototypes made of wax, gypsum, and lead-solder. The emerging chaotic behaviour in all three cases has been studied and evaluated by the related time-series analysis and the calculation of the strange attractors' invariant parameters. PMID:24511290

  2. Analysis of rattleback chaotic oscillations.

    PubMed

    Hanias, Michael; Stavrinides, Stavros G; Banerjee, Santo

    2014-01-01

    Rattleback is a canoe-shaped object, already known from ancient times, exhibiting a nontrivial rotational behaviour. Although its shape looks symmetric, its kinematic behaviour seems to be asymmetric. When spun in one direction it normally rotates, but when it is spun in the other direction it stops rotating and oscillates until it finally starts rotating in the other direction. It has already been reported that those oscillations demonstrate chaotic characteristics. In this paper, rattleback's chaotic dynamics are studied by applying Kane's model for different sets of (experimentally decided) parameters, which correspond to three different experimental prototypes made of wax, gypsum, and lead-solder. The emerging chaotic behaviour in all three cases has been studied and evaluated by the related time-series analysis and the calculation of the strange attractors' invariant parameters. PMID:24511290

  3. In vitro developmental competence of pig nuclear transferred embryos: effects of GFP transfection, refrigeration, cell cycle synchronization and shapes of donor cells.

    PubMed

    Zhang, Yun-Hai; Pan, Deng-Ke; Sun, Xiu-Zhu; Sun, Guo-Jie; Liu, Xiao-Hui; Wang, Xiao-Bo; Tian, Xing-Hua; Li, Yan; Dai, Yun-Ping; Li, Ning

    2006-08-01

    The present study was designed to evaluate the feasibility of producing pig transgenic blastocysts expressing enhanced green fluorescent protein (GFP) and to examine the effects of shape and preparation methods of donor cells on in vitro developmental ability of pig nuclear transferred embryos (NTEs). In experiment 1, the effect of GFP transfection on development of pig NTEs was evaluated. The cleavage and blastocyst rates showed no significant difference between NTEs derived from transfected and non-transfected donors. In experiment 2, the effect of different nuclear donor preparation methods on in vitro development of NTEs was examined. The cleavage rate showed no statistically significant differences among three preparation methods. The blastocyst rates of donor cells treated once at -4 degrees C and those of freshly digested cells were similar to each other (26.3% vs 17.9%). The lowest blastocyst rates (5.88%) were observed when cells cryopreserved at -196 degrees C were used as donors. In experiment 3, the effect of different cell cycle synchronization methods on the in vitro development potential of pig NTEs was evaluated. The cleavage rate of NTEs derived from cycling cells was much better than that of NTEs derived from serum-starved cells (64.4% vs 50.5%, p < 0.05), but no significant difference was observed between the the blastocyst rates of the two groups. In experiment 4, the effect of different shapes of cultured fibroblast cells on the in vitro development of pig NTEs was examined. The fusion rate for couplets derived from rough cells was poorer than that observed in couplets derived from round smooth cells (47.8% vs 76.8%, p < 0.05). However, there were no significant differences observed in the cleavage rate and blastocyst rate. In conclusion, the present study indicated that (i) refrigerated pig GFP-transfected cells could be used as donors in nuclear transfer and these NTEs could be effectively developed to blastocyst stage; (ii) serum starvation

  4. Quantitative analysis of nuclear shape in oral squamous cell carcinoma is useful for predicting the chemotherapeutic response.

    PubMed

    Ogura, Maki; Yamamoto, Yoichiro; Miyashita, Hitoshi; Kumamoto, Hiroyuki; Fukumoto, Manabu

    2016-06-01

    The number of people afflicted with oral carcinoma in Japan has increased in recent years. Although preoperative neoadjuvant therapy with cisplatin and 5-fluorouracil are performed, chemotherapeutic response varies widely among the patients. With the aim of establishing novel indices to predict the therapeutic response to chemotherapy, we investigated the relationship between morphological features of pre-treatment oral carcinoma nuclei and the chemotherapeutic response using quantifying morphology of cell nuclei in pathological specimen images. We measured 4 morphological features of the nucleus of oral squamous cell carcinoma cases classified by the response to chemotherapy: No Change (NC) group, Partial Response (PR) group and Complete Response (CR) group. Furthermore, we performed immunohistochemical staining for p53 and Ki67 and calculated their positive rates in cancer tissues. Compactness and symmetry of the nucleus were significantly higher and nuclear edge response was significantly lower in cancer cells with lower chemotherapeutic responses compared high chemotherapeutic responders. As for positive rates of p53 and Ki67, there were no significant differences between any of the response groups. Morphological features of cancer cell nuclei in pathological specimens are sensitive predictive factors for the chemotherapeutic response to oral squamous cell carcinoma. PMID:26439725

  5. Collagen Substrate Stiffness Anisotropy Affects Cellular Elongation, Nuclear Shape, and Stem Cell Fate toward Anisotropic Tissue Lineage.

    PubMed

    Islam, Anowarul; Younesi, Mousa; Mbimba, Thomas; Akkus, Ozan

    2016-09-01

    Rigidity of substrates plays an important role in stem cell fate. Studies are commonly carried out on isotropically stiff substrate or substrates with unidirectional stiffness gradients. However, many native tissues are anisotropically stiff and it is unknown whether controlled presentation of stiff and compliant material axes on the same substrate governs cytoskeletal and nuclear morphology, as well as stem cell differentiation. In this study, electrocompacted collagen sheets are stretched to varying degrees to tune the stiffness anisotropy (SA) in the range of 1 to 8, resulting in stiff and compliant material axes orthogonal to each other. The cytoskeletal aspect ratio increased with increasing SA by about fourfold. Such elongation was absent on cellulose acetate replicas of aligned collagen surfaces indicating that the elongation was not driven by surface topography. Mesenchymal stem cells (MSCs) seeded on varying anisotropy sheets displayed a dose-dependent upregulation of tendon-related markers such as Mohawk and Scleraxis. After 21 d of culture, highly anisotropic sheets induced greater levels of production of type-I, type-III collagen, and thrombospondin-4. Therefore, SA has direct effects on MSC differentiation. These findings may also have ramifications of stem cell fate on other anisotropically stiff tissues, such as skeletal/cardiac muscles, ligaments, and bone. PMID:27377355

  6. Alpha-particle and proton probes of nuclear shapes in the rare earth and mass 80 regions

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M.; Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A.; Griffin, H.C.; Oak Ridge National Lab., TN; Michigan Univ., Ann Arbor, MI )

    1989-01-01

    Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. To explore the possibility of a correlation between the proton emission barriers and nuclear deformation, we studied proton spectra from the {sup 52}Cr({sup 34}S,2p2n){sup 82}Sr reaction. The proton spectra were observed with the Dwarf-Ball 4{pi} CsI(Tl) array, in coincidence with 18 Compton suppressed Ge detectors operated in conjunction with the Spin Spectrometer, a 4{pi} NaI(Tl) array. We found significant changes and shifts in the proton energy spectra as we selected gating transitions from bands of different moments of inertia or transitions from states of different spin in the same band. Substantial differences were also seen as a function of the {gamma}-ray multiplicity. These results are discussed in terms of statistical model calculations incorporating deformation and structure effects of the emitting system. 20 refs., 9 figs.

  7. Oscillating Permanent Magnets.

    ERIC Educational Resources Information Center

    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)

  8. Solving the eigenvalue problem of the nuclear Yukawa-folded mean-field Hamiltonian

    NASA Astrophysics Data System (ADS)

    Dobrowolski, A.; Pomorski, K.; Bartel, J.

    2016-02-01

    The nuclear Hamiltonian with a Yukawa-folded mean-field potential is diagonalized within the basis of a deformed harmonic-oscillator in Cartesian coordinates. The nuclear shape is characterized by the equivalent sharp surface described either by the well known Funny-Hills or the Trentalange-Koonin-Sierk parametrizations. They are both able to describe a very vast variety of nuclear deformations, including necked-in shapes, left-right asymmetry and non-axiality. The only imposed limitation on the nuclear shape is the z-signature symmetry, which corresponds to a symmetry of the shape with respect to a rotation by an angle π around the z-axis. On output, the computer code produces for a given nucleus with mass number A and charge number Z the energy eigenvalues and eigenfunctions of the mean-field Hamiltonian at chosen deformation.

  9. Oscillation quenching mechanisms: Amplitude vs. oscillation death

    NASA Astrophysics Data System (ADS)

    Koseska, Aneta; Volkov, Evgeny; Kurths, Jürgen

    2013-10-01

    Oscillation quenching constitutes a fundamental emergent phenomenon in systems of coupled nonlinear oscillators. Its importance for various natural and man-made systems, ranging from climate, lasers, chemistry and a wide range of biological oscillators can be projected from two main aspects: (i) suppression of oscillations as a regulator of certain pathological cases and (ii) a general control mechanism for technical systems. We distinguish two structurally distinct oscillation quenching types: oscillation (OD) and amplitude death (AD) phenomena. In this review we aim to set clear boundaries between these two very different oscillation quenching manifestations and demonstrate the importance for their correct identification from the aspect of theory as well as of applications. Moreover, we pay special attention to the physiological interpretation of OD and AD in a large class of biological systems, further underlying their different properties. Several open issues and challenges that await further resolving are also highlighted.

  10. Cloning and Functional Analysis of Histones H3 and H4 in Nuclear Shaping during Spermatogenesis of the Chinese Mitten Crab, Eriocheir sinensis

    PubMed Central

    Wu, Jiang-Li; Kang, Xian-Jiang; Guo, Ming-Shen; Mu, Shu-Mei; Zhang, Zhao-Hui

    2015-01-01

    During spermatogenesis in most animals, the basic proteins associated with DNA are continuously changing and somatic-typed histones are partly replaced by sperm-specific histones, which are then successively replaced by transition proteins and protamines. With the replacement of sperm nuclear basic proteins, nuclei progressively undergo chromatin condensation. The Chinese Mitten Crab (Eriocheir sinensis) is also known as the hairy crab or river crab (phylum Arthropoda, subphylum Crustacea, order Decapoda, and family Grapsidae). The spermatozoa of this species are aflagellate, and each has a spherical acrosome surrounded by a cup-shaped nucleus, peculiar to brachyurans. An interesting characteristic of the E. sinensis sperm nucleus is its lack of electron-dense chromatin. However, its formation is not clear. In this study, sequences encoding histones H3 and H4 were cloned by polymerase chain reaction amplification. Western blotting indicated that H3 and H4 existed in the sperm nuclei. Immunofluorescence and ultrastructural immunocytochemistry demonstrated that histones H3 and H4 were both present in the nuclei of spermatogonia, spermatocytes, spermatids and mature spermatozoa. The nuclear labeling density of histone H4 decreased in sperm nuclei, while histone H3 labeling was not changed significantly. Quantitative real-time PCR showed that the mRNA expression levels of histones H3 and H4 were higher at mitotic and meiotic stages than in later spermiogenesis. Our study demonstrates that the mature sperm nuclei of E. sinensis contain histones H3 and H4. This is the first report that the mature sperm nucleus of E. sinensis contains histones H3 and H4. This finding extends the study of sperm histones of E. sinensis and provides some basic data for exploring how decapod crustaceans form uncondensed sperm chromatin. PMID:25993499

  11. Nonlinear oscillations of inviscid free drops

    NASA Technical Reports Server (NTRS)

    Patzek, T. W.; Benner, R. E., Jr.; Basaran, O. A.; Scriven, L. E.

    1991-01-01

    The present analysis of free liquid drops' inviscid oscillations proceeds through solution of Bernoulli's equation to obtain the free surface shape and of Laplace's equation for the velocity potential field. Results thus obtained encompass drop-shape sequences, pressure distributions, particle paths, and the temporal evolution of kinetic and surface energies; accuracy is verified by the near-constant drop volume and total energy, as well as the diminutiveness of mass and momentum fluxes across drop surfaces. Further insight into the nature of oscillations is provided by Fourier power spectrum analyses of mode interactions and frequency shifts.

  12. Midpoint Shapes.

    ERIC Educational Resources Information Center

    Welchman, Rosamond; Urso, Josephine

    2000-01-01

    Emphasizes the importance of children exploring hands-on and minds-on mathematics. Presents a midpoint shape activity for students to explore the midpoint shape of familiar quadrilaterals, such as squares and rectangles. (KHR)

  13. Analysis of nuclear reactor instability phenomena

    SciTech Connect

    Lahey, R.T. Jr.

    1993-01-01

    The phenomena known as density-wave instability often occurs in phase change systems, such as boiling water nuclear reactors (BWRS). Our current understanding of density-wave oscillations is in fairly good shape for linear phenomena (eg, the onset of instabilities) but is not very advanced for non-linear phenomena [Lahey and Podowski, 1989]. In particular, limit cycle and chaotic instability modes are not well understood in boiling systems such as current and advanced generation BWRs (eg, SBWR). In particular, the SBWR relies on natural circulation and is thus inherently prone to problems with density-wave instabilities. The purpose of this research is to develop a quantitative understanding of nonlinear nuclear-coupled density-wave instability phenomena in BWRS. This research builds on the work of Achard et al [1985] and Clausse et al [1991] who showed, respectively, that Hopf bifurcations and chaotic oscillations may occur in boiling systems.

  14. Synchronization of genetic oscillators

    NASA Astrophysics Data System (ADS)

    Zhou, Tianshou; Zhang, Jiajun; Yuan, Zhanjiang; Chen, Luonan

    2008-09-01

    Synchronization of genetic or cellular oscillators is a central topic in understanding the rhythmicity of living organisms at both molecular and cellular levels. Here, we show how a collective rhythm across a population of genetic oscillators through synchronization-induced intercellular communication is achieved, and how an ensemble of independent genetic oscillators is synchronized by a common noisy signaling molecule. Our main purpose is to elucidate various synchronization mechanisms from the viewpoint of dynamics, by investigating the effects of various biologically plausible couplings, several kinds of noise, and external stimuli. To have a comprehensive understanding on the synchronization of genetic oscillators, we consider three classes of genetic oscillators: smooth oscillators (exhibiting sine-like oscillations), relaxation oscillators (displaying jump dynamics), and stochastic oscillators (noise-induced oscillation). For every class, we further study two cases: with intercellular communication (including phase-attractive and repulsive coupling) and without communication between cells. We find that an ensemble of smooth oscillators has different synchronization phenomena from those in the case of relaxation oscillators, where noise plays a different but key role in synchronization. To show differences in synchronization between them, we make comparisons in many aspects. We also show that a population of genetic stochastic oscillators have their own synchronization mechanisms. In addition, we present interesting phenomena, e.g., for relaxation-type stochastic oscillators coupled to a quorum-sensing mechanism, different noise intensities can induce different periodic motions (i.e., inhomogeneous limit cycles).

  15. Microscopic description of nuclear shapes

    SciTech Connect

    Egido, J.L.; Robledo, L.M.; Valor, A.; Villafranca, A.

    1996-12-31

    The approximate particle number theory for density dependent forces is sketched, the theory is applied to discuss properties of the superdeformed ground state and excited bands of {sup 192}Hg. The force used in the calculations is the finite range density dependent Gogny force. The agreement with the available experimental results is very satisfactory.

  16. 2H nuclear magnetic resonance order parameter profiles suggest a change of molecular shape for phosphatidylcholines containing a polyunsaturated acyl chain.

    PubMed Central

    Holte, L. L.; Peter, S. A.; Sinnwell, T. M.; Gawrisch, K.

    1995-01-01

    Solid-state 2H nuclear magnetic resonance spectroscopy was used to determine the orientational order parameter profiles for a series of phosphatidylcholines with perdeuterated stearic acid, 18:0d35, in position sn-1 and 18:1 omega 9, 18:2 omega 6, 18:3 omega 3, 20:4 omega 6, 20:5 omega 3, or 22:6 omega 3 in position sn-2. The main phase transition temperatures were derived from a first moment analysis, and order parameter profiles of sn-1 chains were calculated from dePaked nuclear magnetic resonance powder patterns. Comparison of the profiles at 37 degrees C showed that unsaturation causes an inhomogenous disordering along the sn-1 chain. Increasing sn-2 chain unsaturation from one to six double bonds resulted in a 1.6-kHz decrease in quadrupolar splittings of the sn-1 chain in the upper half of the chain (or plateau region) and maximum splitting difference of 4.4 kHz at methylene carbon 14. The change in chain order corresponds to a decrease in the 18:0 chain length of 0.4 +/- 0.2 A with 18:2 omega 6 versus 18:1 omega 9 in position sn-2. Fatty acids containing three or more double bonds in sn-2 showed a decrease in sn-1 chain length of 0.7 +/- 0.2 A compared with 18:1 omega 9. The chain length of all lipids decreased with increasing temperature. Highly unsaturated phosphatidylcholines (three or more double bonds in sn-2) had shorter sn-1 chains, but the chain length was somewhat less sensitive to temperature. The profiles reveal that the sn-1 chain exhibits a selective increase in motional freedom in a region located toward the bottom half of the chain as sn-2 unsaturation is increased. This corresponds to an area increase around carbon atom number 14 that is three to four times greater than the increase for the top part of the chain. A similar asymmetric decrease in order, largest toward the methyl end of the chain, was observed when 1 -palmitoyl-2-oleoylphosphatidylethanolamine goes from a lamellar to an inverse hexagonal (H,,) phase. This is consistent with a

  17. Dirac oscillator and nonrelativistic Snyder-de Sitter algebra

    SciTech Connect

    Stetsko, M. M. E-mail: mykola@ktf.franko.lviv.ua

    2015-01-15

    Three dimensional Dirac oscillator was considered in space with deformed commutation relations known as Snyder-de Sitter algebra. Snyder-de Sitter commutation relations give rise to appearance of minimal uncertainties in position as well as in momentum. To derive energy spectrum and wavefunctions of the Dirac oscillator, supersymmetric quantum mechanics and shape invariance technique were applied.

  18. Dirac oscillator and nonrelativistic Snyder-de Sitter algebra

    NASA Astrophysics Data System (ADS)

    Stetsko, M. M.

    2015-01-01

    Three dimensional Dirac oscillator was considered in space with deformed commutation relations known as Snyder-de Sitter algebra. Snyder-de Sitter commutation relations give rise to appearance of minimal uncertainties in position as well as in momentum. To derive energy spectrum and wavefunctions of the Dirac oscillator, supersymmetric quantum mechanics and shape invariance technique were applied.

  19. The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the full shape of the clustering wedges in the data release 10 and 11 galaxy samples

    NASA Astrophysics Data System (ADS)

    Sánchez, Ariel G.; Montesano, Francesco; Kazin, Eyal A.; Aubourg, Eric; Beutler, Florian; Brinkmann, Jon; Brownstein, Joel R.; Cuesta, Antonio J.; Dawson, Kyle S.; Eisenstein, Daniel J.; Ho, Shirley; Honscheid, Klaus; Manera, Marc; Maraston, Claudia; McBride, Cameron K.; Percival, Will J.; Ross, Ashley J.; Samushia, Lado; Schlegel, David J.; Schneider, Donald P.; Skibba, Ramin; Thomas, Daniel; Tinker, Jeremy L.; Tojeiro, Rita; Wake, David A.; Weaver, Benjamin A.; White, Martin; Zehavi, Idit

    2014-05-01

    We explore the cosmological implications of the angle-averaged correlation function, ξ(s), and the clustering wedges, ξ⊥(s) and ξ∥(s), of the LOWZ and CMASS galaxy samples from Data Releases 10 and 11 of the Sloan Digital Sky Survey III (SDSS-III) Baryon Oscillation Spectroscopic Survey. Our results show no significant evidence for a deviation from the standard Λ cold dark matter model. The combination of the information from our clustering measurements with recent data from the cosmic microwave background is sufficient to constrain the curvature of the Universe to Ωk = 0.0010 ± 0.0029, the total neutrino mass to ∑mν < 0.23 eV (95 per cent confidence level), the effective number of relativistic species to Neff = 3.31 ± 0.27 and the dark energy equation of state to wDE = -1.051 ± 0.076. These limits are further improved by adding information from Type Ia supernovae and baryon acoustic oscillations from other samples. In particular, this data set combination is completely consistent with a time-independent dark energy equation of state, in which case we find wDE = -1.024 ± 0.052. We explore the constraints on the growth rate of cosmic structures assuming f(z) = Ωm(z)γ and obtain γ = 0.69 ± 0.15, consistent with the predictions of general relativity of γ = 0.55.

  20. Synchronizing redundant power oscillators

    NASA Technical Reports Server (NTRS)

    Jenson, K. J.

    1969-01-01

    Outputs of oscillators are synchronized by summing the power transformer phase voltages, the summed voltages are applied to the frequency determining inductors of the individual voltage-controlled power oscillators. The beat frequency is eliminated when synchronization is achieved.

  1. Saturation in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Roman, Ahmed; Hanna, James

    2015-03-01

    We consider a weakly nonlinear system consisting of a resonantly forced oscillator coupled to an unforced oscillator. It has long been known that, for quadratic nonlinearities and a 2:1 resonance between the oscillators, a perturbative solution of the dynamics exhibits a phenomenon known as saturation. At low forcing, the forced oscillator responds, while the unforced oscillator is quiescent. Above a critical value of the forcing, the forced oscillator's steady-state amplitude reaches a plateau, while that of the unforced oscillator increases without bound. We show that, contrary to established folklore, saturation is not unique to quadratically nonlinear systems. We present conditions on the form of the nonlinear couplings and resonance that lead to saturation. Our results elucidate a mechanism for localization or diversion of energy in systems of coupled oscillators, and suggest new approaches for the control or suppression of vibrations in engineered systems.

  2. Microelectronic oscillator, 2

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1969-01-01

    Microelectronic oscillator uses a bipolar transistor to circumvent the problem of developing suitable inductors for lower frequencies. The oscillator is fabricated by hybrid thin film techniques or by monolithic construction. Discrete microminiature components may also be employed.

  3. Fine tuning of cytosolic Ca 2+ oscillations

    PubMed Central

    Dupont, Geneviève; Combettes, Laurent

    2016-01-01

    Ca 2+ oscillations, a widespread mode of cell signaling, were reported in non-excitable cells for the first time more than 25 years ago. Their fundamental mechanism, based on the periodic Ca 2+ exchange between the endoplasmic reticulum and the cytoplasm, has been well characterized. However, how the kinetics of cytosolic Ca 2+ changes are related to the extent of a physiological response remains poorly understood. Here, we review data suggesting that the downstream targets of Ca 2+ are controlled not only by the frequency of Ca 2+ oscillations but also by the detailed characteristics of the oscillations, such as their duration, shape, or baseline level. Involvement of non-endoplasmic reticulum Ca 2+ stores, mainly mitochondria and the extracellular medium, participates in this fine tuning of Ca 2+ oscillations. The main characteristics of the Ca 2+ exchange fluxes with these compartments are also reviewed.

  4. Oscillations in SIRS model with distributed delays

    NASA Astrophysics Data System (ADS)

    Gonçalves, S.; Abramson, G.; Gomes, M. F. C.

    2011-06-01

    The ubiquity of oscillations in epidemics presents a long standing challenge for the formulation of epidemic models. Whether they are external and seasonally driven, or arise from the intrinsic dynamics is an open problem. It is known that fixed time delays destabilize the steady state solution of the standard SIRS model, giving rise to stable oscillations for certain parameters values. In this contribution, starting from the classical SIRS model, we make a general treatment of the recovery and loss of immunity terms. We present oscillation diagrams (amplitude and period) in terms of the parameters of the model, showing how oscillations can be destabilized by the shape of the distributions of the two characteristic (infectious and immune) times. The formulation is made in terms of delay equations which are both numerically integrated and linearized. Results from simulations are included showing where they support the linear analysis and explaining why not where they do not. Considerations and comparison with real diseases are presented along.

  5. BMAL1-dependent circadian oscillation of nuclear CLOCK: posttranslational events induced by dimerization of transcriptional activators of the mammalian clock system

    PubMed Central

    Kondratov, Roman V.; Chernov, Mikhail V.; Kondratova, Anna A.; Gorbacheva, Victoria Y.; Gudkov, Andrei V.; Antoch, Marina P.

    2003-01-01

    Mammalian CLOCK and BMAL1 are two members of bHLH-PAS-containing family of transcription factors that represent the positive elements of circadian autoregulatory feedback loop. In the form of a heterodimer, they drive transcription from E-box enhancer elements in the promoters of responsive genes. We have examined abundance, posttranslational modifications, cellular localization of endogenous and ectopically expressed CLOCK and BMAL1 proteins. Nuclear/cytoplasm distribution of CLOCK was found to be under circadian regulation. Analysis of subcellular localization of CLOCK in embryo fibroblasts of mice carrying different germ-line circadian mutations showed that circadian regulation of nuclear accumulation of CLOCK is BMAL1-dependent. Formation of CLOCK/BMAL1 complex following ectopic coexpression of both proteins is followed by their codependent phosphorylation, which is tightly coupled to CLOCK nuclear translocation and degradation. This binding-dependent coregulation is specific for CLOCK/BMAL1 interaction, as no other PAS domain protein that can form a complex with either CLOCK or BMAL1 was able to induce similar effects. Importantly, all posttranslational events described in our study are coupled with active transactivation complex formation, which argues for their significant functional role. Altogether, these results provide evidence for an additional level of circadian system control, which is based on regulation of transcriptional activity or/and availability of CLOCK/BMAL1 complex. PMID:12897057

  6. Covariant harmonic oscillators and coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    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.

  7. Schapiro Shapes

    ERIC Educational Resources Information Center

    O'Connell, Emily

    2009-01-01

    This article describes a lesson on Schapiro Shapes. Schapiro Shapes is based on the art of Miriam Schapiro, who created a number of works of figures in action. Using the basic concepts of this project, students learn to create their own figures and styles. (Contains 1 online resource.)

  8. SHOCK-EXCITED OSCILLATOR

    DOEpatents

    Creveling, R.

    1957-12-17

    S> A shock-excited quartz crystal oscillator is described. The circuit was specifically designed for application in micro-time measuring work to provide an oscillator which immediately goes into oscillation upon receipt of a trigger pulse and abruptly ceases oscillation when a second pulse is received. To achieve the instant action, the crystal has a prestressing voltage applied across it. A monostable multivibrator receives the on and off trigger pulses and discharges a pulse through the crystal to initiate or terminate oscillation instantly.

  9. Discrete monotron oscillator

    SciTech Connect

    Carlsten, B.E.; Haynes, W.B.

    1996-08-01

    The authors theoretically and numerically investigate the operation and behavior of the discrete monotron oscillator, a novel high-power microwave source. The discrete monotron differs from conventional monotrons and transit time oscillators by shielding the electron beam from the monotron cavity`s RF fields except at two distinct locations. This makes the discrete monotron act more like a klystron than a distributed traveling wave device. As a result, the oscillator has higher efficiency and can operate with higher beam powers than other single cavity oscillators and has more stable operation without requiring a seed input signal than mildly relativistic, intense-beam klystron oscillators.

  10. Nature's Autonomous Oscillators

    NASA Technical Reports Server (NTRS)

    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.

  11. Non-linear oscillations

    NASA Astrophysics Data System (ADS)

    Hagedorn, P.

    The mathematical pendulum is used to provide a survey of free and forced oscillations in damped and undamped systems. This simple model is employed to present illustrations for and comparisons between the various approximation schemes. A summary of the Liapunov stability theory is provided. The first and the second method of Liapunov are explained for autonomous as well as for nonautonomous systems. Here, a basic familiarity with the theory of linear oscillations is assumed. La Salle's theorem about the stability of invariant domains is explained in terms of illustrative examples. Self-excited oscillations are examined, taking into account such oscillations in mechanical and electrical systems, analytical approximation methods for the computation of self-excited oscillations, analytical criteria for the existence of limit cycles, forced oscillations in self-excited systems, and self-excited oscillations in systems with several degrees of freedom. Attention is given to Hamiltonian systems and an introduction to the theory of optimal control is provided.

  12. Aphanomyces euteiches cell wall fractions containing novel glucan-chitosaccharides induce defense genes and nuclear calcium oscillations in the plant host Medicago truncatula.

    PubMed

    Nars, Amaury; Lafitte, Claude; Chabaud, Mireille; Drouillard, Sophie; Mélida, Hugo; Danoun, Saïda; Le Costaouëc, Tinaig; Rey, Thomas; Benedetti, Julie; Bulone, Vincent; Barker, David George; Bono, Jean-Jacques; Dumas, Bernard; Jacquet, Christophe; Heux, Laurent; Fliegmann, Judith; Bottin, Arnaud

    2013-01-01

    N-acetylglucosamine-based saccharides (chitosaccharides) are components of microbial cell walls and act as molecular signals during host-microbe interactions. In the legume plant Medicago truncatula, the perception of lipochitooligosaccharide signals produced by symbiotic rhizobia and arbuscular mycorrhizal fungi involves the Nod Factor Perception (NFP) lysin motif receptor-like protein and leads to the activation of the so-called common symbiotic pathway. In rice and Arabidopsis, lysin motif receptors are involved in the perception of chitooligosaccharides released by pathogenic fungi, resulting in the activation of plant immunity. Here we report the structural characterization of atypical chitosaccharides from the oomycete pathogen Aphanomyces euteiches, and their biological activity on the host Medicago truncatula. Using a combination of biochemical and biophysical approaches, we show that these chitosaccharides are linked to β-1,6-glucans, and contain a β-(1,3;1,4)-glucan backbone whose β-1,3-linked glucose units are substituted on their C-6 carbon by either glucose or N-acetylglucosamine residues. This is the first description of this type of structural motif in eukaryotic cell walls. Glucan-chitosaccharide fractions of A. euteiches induced the expression of defense marker genes in Medicago truncatula seedlings independently from the presence of a functional Nod Factor Perception protein. Furthermore, one of the glucan-chitosaccharide fractions elicited calcium oscillations in the nucleus of root cells. In contrast to the asymmetric oscillatory calcium spiking induced by symbiotic lipochitooligosaccharides, this response depends neither on the Nod Factor Perception protein nor on the common symbiotic pathway. These findings open new perspectives in oomycete cell wall biology and elicitor recognition and signaling in legumes. PMID:24086432

  13. Aphanomyces euteiches Cell Wall Fractions Containing Novel Glucan-Chitosaccharides Induce Defense Genes and Nuclear Calcium Oscillations in the Plant Host Medicago truncatula

    PubMed Central

    Nars, Amaury; Lafitte, Claude; Chabaud, Mireille; Drouillard, Sophie; Mélida, Hugo; Danoun, Saïda; Le Costaouëc, Tinaig; Rey, Thomas; Benedetti, Julie; Bulone, Vincent; Barker, David George; Bono, Jean-Jacques; Dumas, Bernard; Jacquet, Christophe; Heux, Laurent; Fliegmann, Judith; Bottin, Arnaud

    2013-01-01

    N-acetylglucosamine-based saccharides (chitosaccharides) are components of microbial cell walls and act as molecular signals during host-microbe interactions. In the legume plant Medicago truncatula, the perception of lipochitooligosaccharide signals produced by symbiotic rhizobia and arbuscular mycorrhizal fungi involves the Nod Factor Perception (NFP) lysin motif receptor-like protein and leads to the activation of the so-called common symbiotic pathway. In rice and Arabidopsis, lysin motif receptors are involved in the perception of chitooligosaccharides released by pathogenic fungi, resulting in the activation of plant immunity. Here we report the structural characterization of atypical chitosaccharides from the oomycete pathogen Aphanomyces euteiches, and their biological activity on the host Medicago truncatula. Using a combination of biochemical and biophysical approaches, we show that these chitosaccharides are linked to β-1,6-glucans, and contain a β-(1,3;1,4)-glucan backbone whose β-1,3-linked glucose units are substituted on their C-6 carbon by either glucose or N-acetylglucosamine residues. This is the first description of this type of structural motif in eukaryotic cell walls. Glucan-chitosaccharide fractions of A. euteiches induced the expression of defense marker genes in Medicago truncatula seedlings independently from the presence of a functional Nod Factor Perception protein. Furthermore, one of the glucan-chitosaccharide fractions elicited calcium oscillations in the nucleus of root cells. In contrast to the asymmetric oscillatory calcium spiking induced by symbiotic lipochitooligosaccharides, this response depends neither on the Nod Factor Perception protein nor on the common symbiotic pathway. These findings open new perspectives in oomycete cell wall biology and elicitor recognition and signaling in legumes. PMID:24086432

  14. Electromagnetic radiation due to nonlinear oscillations of a charged drop

    NASA Astrophysics Data System (ADS)

    Shiryaeva, S. O.; Grigor'ev, A. N.; Kolbneva, N. Yu.

    2016-03-01

    The nonlinear oscillations of a spherical charged drop are asymptotically analyzed under the conditions of a multimode initial deformation of its equilibrium shape. It is found that if the spectrum of initially excited modes contains two adjacent modes, the translation mode of oscillations is excited among others. In this case, the center of the drop's charge oscillates about the equilibrium position, generating a dipole electromagnetic radiation. It is shown that the intensity of this radiation is many orders of magnitude higher than the intensity of the drop's radiation, which arises in calculations of the first order of smallness and is related to the drop's charged surface oscillations.

  15. Parametrically excited sectorial oscillation of liquid drops floating in ultrasound

    NASA Astrophysics Data System (ADS)

    Shen, C. L.; Xie, W. J.; Wei, B.

    2010-04-01

    We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters.

  16. Parametrically excited sectorial oscillation of liquid drops floating in ultrasound.

    PubMed

    Shen, C L; Xie, W J; Wei, B

    2010-04-01

    We report experiments in which the nonaxisymmetric sectorial oscillations of water drops have been excited using acoustic levitation and an active modulation method. The observed stable sectorial oscillations are up to the seventh mode. These oscillations are excited by parametric resonance. The oblate initial shape of the water drops is essential to this kind of excitations. The oscillation frequency increases with mode number but decreases with equatorial radius for each mode number. The data can be well described by a modified Rayleigh equation, without the use of additional parameters. PMID:20481825

  17. A theoretical study of rotational diffusion models for rod-shaped viruses. The influence of motion on 31P nuclear magnetic resonance lineshapes and transversal relaxation.

    PubMed Central

    Magusin, P C; Hemminga, M A

    1993-01-01

    Information about the interaction between nucleic acids and coat proteins in intact virus particles may be obtained by studying the restricted backbone dynamics of the incapsulated nucleic acids using 31P nuclear magnetic resonance (NMR) spectroscopy. In this article, simulations are carried out to investigate how reorientation of a rod-shaped virus particle as a whole and isolated nucleic acid motions within the virion influence the 31P NMR lineshape and transversal relaxation dominated by the phosphorus chemical shift anisotropy. Two opposite cases are considered on a theoretical level. First, isotropic rotational diffusion is used as a model for mobile nucleic acids that are loosely or partially bound to the protein coat. The effect of this type of diffusion on lineshape and transversal relaxation is calculated by solving the stochastic Liouville equation by an expansion in spherical functions. Next, uniaxial rotational diffusion is assumed to represent the mobility of phosphorus in a virion that rotates as a rigid rod about its length axis. This type of diffusion is approximated by an exchange process among discrete sites. As turns out from these simulations, the amplitude and the frequency of the motion can only be unequivocally determined from experimental data by a combined analysis of the lineshape and the transversal relaxation. In the fast motional region both the isotropic and the uniaxial diffusion model predict the same transversal relaxation as the Redfield theory. For very slow motion, transversal relaxation resembles the nonexponential relaxation as observed for water molecules undergoing translational diffusion in a magnetic field gradient. In this frequency region T2e is inversely proportional to the cube root of the diffusion coefficient. In addition to the isotropic and uniaxial diffusion models, a third model is presented, in which fast restricted nucleic acid backbone motions dominating the lineshape are superimposed on a slow rotation of the

  18. Nuclear shape descriptors by automated morphometry may distinguish aggressive variants of squamous cell carcinoma from relatively benign skin proliferative lesions: a pilot study.

    PubMed

    Yang, Weixi; Tian, Rong; Xue, Tongqing

    2015-08-01

    We evaluated whether degrees of dysplasia may be consistently accessed in an automatic fashion, using different kinds of non-melanoma skin cancer (NMSC) as a validatory model. Namely, we compared Bowen disease, actinic keratosis, basal cell carcinoma, low-grade squamous cell carcinoma, and invasive squamous cell carcinoma. We hypothesized that characterizing the shape of nuclei may be important to consistently diagnose the aggressiveness of a skin tumor. While basal cell carcinoma is comparatively relatively benign, management of squamous cell carcinoma is controversial because of its potential to recur and intraoperative dilemma regarding choice of the margin or the depth for the excision. We provide evidence here that progressive nuclear dysplasia may be automatically estimated through the thresholded images of skin cancer and quantitative parameters estimated to provide a quasi-quantitative data, which can thenceforth guide the management of the particular cancer. For circularity, averaging more than 2500 nuclei in each group estimated the means ± SD as 0.8 ± 0.007 vs. 0.78 ± 0.0063 vs. 0.42 ± 0.014 vs. 0.63 ± 0.02 vs. 0.51 ± 0.02 (F = 318063.56, p < 0.0001, one-way analyses of variance). The mean aspect ratios were (means ± SD) 0.97 ± 0.0014 vs. 0.95 ± 0.002 vs. 0.38 ± 0.018 vs. 0.84 ± 0.0035 vs. 0.74 ± 0.019 (F = 1022631.931, p < 0.0001, one-way analyses of variance). The Feret diameters averaged over 2500 nuclei in each group were the following: 1 ± 0.0001 vs. 0.9 ± 0.002 vs. 5 ± 0.031 vs. 1.5 ± 0.01 vs. 1.9 ± 0.004 (F = 33105614.194, p < 0.0001, one-way analyses of variance). Multivariate analyses of composite parameters potentially detect aggressive variants of squamous cell carcinoma as the most dysplastic form, in comparison to locally occurring squamous cell carcinoma and basal cell carcinoma, or benign skin lesions. PMID:25753477

  19. Superimposed oscillations in brane inflation

    SciTech Connect

    Ávila, Santiago; Martin, Jérôme; Steer, Danièle A. E-mail: jmartin@iap.fr

    2014-08-01

    In canonical scalar field inflation, the Starobinsky model (with a linear potential but discontinuous slope) is remarkable in that though slow-roll is violated, both the power-spectrum and bi-spectrum can be calculated exactly analytically. The two-point function is characterised by different power on large and small scales, and a burst of small amplitude superimposed oscillations in between. We extend this analysis to Dirac Born Infeld (DBI) inflation, for which generalised slow-roll is violated at the discontinuity and a rapid variation in the speed of sound c{sub S} occurs. In an attempt to characterise the effect of non-linear kinetic terms on the oscillatory features of the primordial power-spectrum, we show that the resulting power spectrum has a shape and features which differ significantly from those of the standard Starobinsky model. In particular, when c{sub S} is small, the power-spectrum now takes very similar scale invariant values on large and small scales, while on intermediate scales it is characterised by much larger amplitude and higher frequency superimposed oscillations. We also show that calculating non-Gaussianities in this model is a complicated but interesting task since all terms in the cubic action now contribute. Investigating whether the superimposed oscillations could fit to the Planck Cosmic Microwave Background (CMB) data (for instance by explaining the large scale Planck anomalies) with, at the same time, small non-Gaussianities remains an intriguing and open possibility.

  20. Galactic oscillator symmetry

    NASA Technical Reports Server (NTRS)

    Rosensteel, George

    1995-01-01

    Riemann ellipsoids model rotating galaxies when the galactic velocity field is a linear function of the Cartesian coordinates of the galactic masses. In nuclear physics, the kinetic energy in the linear velocity field approximation is known as the collective kinetic energy. But, the linear approximation neglects intrinsic degrees of freedom associated with nonlinear velocity fields. To remove this limitation, the theory of symplectic dynamical symmetry is developed for classical systems. A classical phase space for a self-gravitating symplectic system is a co-adjoint orbit of the noncompact group SP(3,R). The degenerate co-adjoint orbit is the 12 dimensional homogeneous space Sp(3,R)/U(3), where the maximal compact subgroup U(3) is the symmetry group of the harmonic oscillator. The Hamiltonian equations of motion on each orbit form a Lax system X = (X,F), where X and F are elements of the symplectic Lie algebra. The elements of the matrix X are the generators of the symplectic Lie algebra, viz., the one-body collective quadratic functions of the positions and momenta of the galactic masses. The matrix F is composed from the self-gravitating potential energy, the angular velocity, and the hydostatic pressure. Solutions to the hamiltonian dynamical system on Sp(3,R)/U(3) are given by symplectic isospectral deformations. The Casimirs of Sp(3,R), equal to the traces of powers of X, are conserved quantities.

  1. Neutrino oscillation studies with reactors

    PubMed Central

    Vogel, P.; Wen, L.J.; Zhang, C.

    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 flavours 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 θ13. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos. PMID:25913819

  2. Neutrino oscillation studies with reactors

    SciTech Connect

    Vogel, P.; Wen, L.J.; Zhang, C.

    2015-04-27

    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 flavours 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 θ13. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.

  3. Neutrino oscillation studies with reactors.

    PubMed

    Vogel, P; Wen, L J; Zhang, C

    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 flavours 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 θ13. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos. PMID:25913819

  4. Neutrino oscillation studies with reactors

    DOE PAGESBeta

    Vogel, P.; Wen, L.J.; Zhang, C.

    2015-04-27

    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 flavours 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 θ13. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.

  5. Paradoxes of neutrino oscillations

    SciTech Connect

    Akhmedov, E. Kh.; Smirnov, A. Yu.

    2009-08-15

    Despite the theory of neutrino oscillations being rather old, some of its basic issues are still being debated in the literature. We discuss a number of such issues, including the relevance of the 'same energy' and 'same momentum' assumptions, the role of quantum-mechanical uncertainty relations in neutrino oscillations, the dependence of the coherence and localization conditions that ensure the observability of neutrino oscillations on neutrino energy and momentum uncertainties, the question of (in)dependence of the oscillation probabilities on the neutrino production and detection processes, and the applicability limits of the stationary-source approximation. We also develop a novel approach to calculation of the oscillation probability in the wave-packet approach, based on the summation/integration conventions different from the standard one, which allows a new insight into the 'same energy' vs. 'same momentum' problem. We also discuss a number of apparently paradoxical features of the theory of neutrino oscillations.

  6. Sizing and shaping the nucleus: mechanisms and significance

    PubMed Central

    Jevtić, Predrag; Edens, Lisa J.; Vuković, Lidija D.; Levy, Daniel L.

    2014-01-01

    The size and shape of the nucleus are tightly regulated, indicating the physiological significance of proper nuclear morphology, yet the mechanisms and functions of nuclear size and shape regulation remain poorly understood. Correlations between altered nuclear morphology and certain disease states have long been observed, most notably many cancers are diagnosed and staged based on graded increases in nuclear size. Here we review recent studies investigating the mechanisms regulating nuclear size and shape, how mitotic events influence nuclear morphology, and the role of nuclear size and shape in subnuclear chromatin organization and cancer progression. PMID:24503411

  7. Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, D. (Editor); Kim, Y. S. (Editor); Zachary, W. W. (Editor)

    1993-01-01

    Proceedings of a workshop on Harmonic Oscillators held at the College Park Campus of the University of Maryland on March 25 - 28, 1992 are presented. The harmonic oscillator formalism is playing an important role in many branches of physics. This is the simplest mathematical device which can connect the basic principle of physics with what is observed in the real world. The harmonic oscillator is the bridge between pure and applied physics.

  8. Boxing with Neutrino Oscillations

    NASA Astrophysics Data System (ADS)

    Wagner, Dj; Weiler, Thomas J.

    1998-03-01

    We have developed a model-independent ``box'' parameterization of neutrino oscillations. Oscillation probabilities are linear in these new parameters, so measurements can straighforwardly determine the box parameters which can then be manipulated to yield magnitudes of mixing matrix elements. We will present these new parameters and examine the effects of unitarity which reduce the number of independent parameters to the minimum set. The framework presented here will facilitate general analyses of neutrino oscillations among n >= 3 flavors.

  9. Self-oscillation

    NASA Astrophysics Data System (ADS)

    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.

  10. Drop oscillation and mass transfer in alternating electric fields

    SciTech Connect

    Carleson, T.E.

    1992-06-24

    In certain cases droplet direct contact heat transfer rates can be significantly enhanced by the application of an alternating electric field. This field can produce shape oscillations in a droplet which will enhance mixing. The theoretical evaluation of the effect of the interaction of the field with drop charge on the hydrodynamics has been completed for small amplitude oscillations. Previous work with a zero order perturbation method was followed up with a first order perturbation method to evaluate the effect of drop distortion on drop charge and field distribution. The first order perturbation results show secondary drop oscillations of four modes and two frequencies in each mode. The most significant secondary oscillation has the same mode and frequency as the second mode oscillation predicted from the first order perturbation work. The resonant frequency of all oscillations decrease with increasing electric field strength and drop charge. Work is currently underway to evaluate the heat transfer enhancement from an applied alternating electric field.

  11. Frequencies of solar oscillations

    NASA Technical Reports Server (NTRS)

    Libbrecht, K. G.; Woodard, M. F.; Kaufman, J. M.

    1990-01-01

    Solar oscillations have been observed at three different spatial scales at Big Bear Solar Observatory during 1986-1987 and, using three data sets, a new and more accurate table of solar oscillation frequencies has been compiled. The oscillations, which are presented as functions of radial order n and spherical harmonic degree l, are averages over azimuthal order and therefore approximate the normal mode frequencies of a nonrotating, spherically symmetric sun, near solar minimum. The table contains frequencies for most of the solar p and f modes with l between 0 and 1860, n between 0 and 26, and oscillation mode frequencies between 1.0 and 5.3.

  12. Torsional oscillations of strange stars

    NASA Astrophysics Data System (ADS)

    Mannarelli, Massimo

    2014-11-01

    Strange stars are one of the hypothetical compact stellar objects that can be formed after a supernova explosion. The existence of these objects relies on the absolute stability of strange collapsed quark matter with respect to standard nuclear matter. We discuss simple models of strange stars with a bare quark matter surface, thus standard nuclear matter is completely absent. In these models an electric dipole layer a few hundreds Fermi thick should exist close to the star surface. Studying the torsional oscillations of the electrically charged layer we estimate the emitted power, finding that it is of the order of 1045 erg/s, meaning that these objects would be among the brightest compact sources in the heavens. The associated relaxation times are very uncertain, with values ranging between microseconds and minutes, depending on the crust thickness. Although part of the radiated power should be absorbed by the electrosphere surrounding the strange star, a sizable fraction of photons should escape and be detectable.

  13. Full jet evolution in quark-gluon plasma and nuclear modification of jet production and jet shape in Pb+Pb collisions at 2.76 A TeV at the CERN Large Hadron Collider

    NASA Astrophysics Data System (ADS)

    Chang, Ning-Bo; Qin, Guang-You

    2016-08-01

    We study the evolution of the full jet shower in quark-gluon plasma by solving a set of coupled differential transport equations for the three-dimensional momentum distributions of quarks and gluons contained in full jets. In our jet evolution equations, we include all partonic splitting processes as well as the collisional energy loss and transverse momentum broadening for both the leading and radiated partons of the full jets. Combining with a realistic (2 +1 )-dimensional viscous hydrodynamic simulation for the spacetime profiles of the hot and dense nuclear medium produced in heavy-ion collisions, we apply our formalism to calculate the nuclear modification of single inclusive full jet spectra, the momentum imbalance of photon-jet and dijet pairs, and the jet shape function (at partonic level) in Pb+Pb collisions at 2.76 A TeV. The roles of various jet-medium interaction mechanisms on the full jet modification are studied. We find that the nuclear modification of jet shape is sensitive to the interplay of different interaction mechanisms as well as the energies of the full jets.

  14. Active-bridge oscillator

    DOEpatents

    Wessendorf, Kurt O.

    2001-01-01

    An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.

  15. Investigating Magnetic Oscillations.

    ERIC Educational Resources Information Center

    Brueningsen, Christopher A.

    1993-01-01

    Studies magnetic oscillation using an air track. Ceramic magnets are attached to the cart and also are used as dampeners in place of the springs. The resulting oscillations are fairly sinusoidal and is a good example of simple harmonic motion. (MVL)

  16. Analysis of nuclear reactor instability phenomena. Progress report

    SciTech Connect

    Lahey, R.T. Jr.

    1993-03-01

    The phenomena known as density-wave instability often occurs in phase change systems, such as boiling water nuclear reactors (BWRS). Our current understanding of density-wave oscillations is in fairly good shape for linear phenomena (eg, the onset of instabilities) but is not very advanced for non-linear phenomena [Lahey and Podowski, 1989]. In particular, limit cycle and chaotic instability modes are not well understood in boiling systems such as current and advanced generation BWRs (eg, SBWR). In particular, the SBWR relies on natural circulation and is thus inherently prone to problems with density-wave instabilities. The purpose of this research is to develop a quantitative understanding of nonlinear nuclear-coupled density-wave instability phenomena in BWRS. This research builds on the work of Achard et al [1985] and Clausse et al [1991] who showed, respectively, that Hopf bifurcations and chaotic oscillations may occur in boiling systems.

  17. HIGH POWER PULSED OSCILLATOR

    DOEpatents

    Singer, S.; Neher, L.K.

    1957-09-24

    A high powered, radio frequency pulse oscillator is described for generating trains of oscillations at the instant an input direct voltage is impressed, or immediately upon application of a light pulse. In one embodiment, the pulse oscillator comprises a photo-multiplier tube with the cathode connected to the first dynode by means of a resistor, and adjacent dynodes are connected to each other through adjustable resistors. The ohmage of the resistors progressively increases from a very low value for resistors adjacent the cathode to a high value adjacent the plate, the last dynode. Oscillation occurs with this circuit when a high negative voltage pulse is applied to the cathode and the photo cathode is bombarded. Another embodiment adds capacitors at the resistor connection points of the above circuit to increase the duration of the oscillator train.

  18. Ultrastable Cryogenic Microwave Oscillators

    NASA Astrophysics Data System (ADS)

    Mann, Anthony G.

    Ultrastable cryogenic microwave oscillators are secondary frequency standards in the microwave domain. The best of these oscillators have demonstrated a short term frequency stability in the range 10-14 to a few times 10-16. The main application for these oscillators is as flywheel oscillators for the next generation of passive atomic frequency standards, and as local oscillators in space telemetry ground stations to clean up the transmitter close in phase noise. Fractional frequency stabilities of passive atomic frequency standards are now approaching 3 x10^-14 /τ where τ is the measurement time, limited only by the number of atoms that are being interrogated. This requires an interrogation oscillator whose short-term stability is of the order of 10-14 or better, which cannot be provided by present-day quartz technology. Ultrastable cryogenic microwave oscillators are based on resonators which have very high electrical Q-factors. The resolution of the resonator's linewidth is typically limited by electronics noise to about 1ppm and hence Q-factors in excess of 108 are required. As these are only attained in superconducting cavities or sapphire resonators at low temperatures, use of liquid helium cooling is mandatory, which has so far restricted these oscillators to the research or metrology laboratory. Recently, there has been an effort to dispense with the need for liquid helium and make compact flywheel oscillators for the new generation of primary frequency standards. Work is under way to achieve this goal in space-borne and mobile liquid-nitrogen-cooled systems. The best cryogenic oscillators developed to date are the ``whispering gallery'' (WG) mode sapphire resonator-oscillators of NASA's Jet Propulsion Laboratory (JPL) and the University of Western Australia (UWA), as well as Stanford University's superconducting cavity stabilized oscillator (SCSO). All of these oscillators have demonstrated frequency

  19. Blocking protein farnesylation improves nuclear shape abnormalities in keratinocytes of mice expressing the prelamin A variant in Hutchinson-Gilford progeria syndrome.

    PubMed

    Wang, Yuexia; Ostlund, Cecilia; Worman, Howard J

    2010-01-01

    Hutchinson-Gilford progeria syndrome (HGPS) is an accelerated aging disorder caused by mutations in LMNA leading to expression of a truncated prelamin A variant termed progerin. Whereas a farnesylated polypeptide is normally removed from the carboxyl-terminus of prelamin A during endoproteolytic processing to lamin A, progerin lacks the cleavage site and remains farnesylated. Cultured cells from human subjects with HGPS and genetically modified mice expressing progerin have nuclear morphological abnormalities, which are reversed by inhibitors of protein farnesylation. In addition, treatment with protein farnesyltransferase inhibitors improves whole animal phenotypes in mouse models of HGPS. However, improvement in nuclear morphology in tissues after treatment of animals has not been demonstrated. We therefore treated transgenic mice that express progerin in epidermis with the protein farnesyltransferase inhibitor FTI-276 or a combination of pravastatin and zoledronate to determine if they reversed nuclear morphological abnormalities in tissue. Immunofluorescence microscopy and "blinded" electron microscopic analysis demonstrated that systemic administration of FTI-276 or pravastatin plus zoledronate significantly improved nuclear morphological abnormalities in keratinocytes of transgenic mice. These results show that pharmacological blockade of protein prenylation reverses nuclear morphological abnormalities that occur in HGPS in vivo. They further suggest that skin biopsy may be useful to determine if protein farnesylation inhibitors are exerting effects in subjects with HGPS in clinical trials. PMID:21326826

  20. Boxing with neutrino oscillations

    NASA Astrophysics Data System (ADS)

    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.

  1. Boxing with neutrino oscillations

    SciTech Connect

    Wagner, D.J.; Weiler, T.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 {open_quotes}boxes{close_quotes} 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 {ital CP}- or {ital T}-even oscillation modes, while the imaginary parts are the coefficients for the {ital CP}- or {ital 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 {ital 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{ge}3 flavors. {copyright} {ital 1999} {ital The American Physical Society}

  2. Drop Ejection From an Oscillating Rod

    NASA Technical Reports Server (NTRS)

    Wilkes, E. D.; Basaran, O. A.

    1999-01-01

    The dynamics of a drop of a Newtonian liquid that is pendant from or sessile on a solid rod that is forced to undergo time-periodic oscillations along its axis is studied theoretically. The free boundary problem governing the time evolution of the shape of the drop and the flow field inside it is solved by a method of lines using a finite element algorithm incorporating an adaptive mesh. When the forcing amplitude is small, the drop approaches a limit cycle at large times and undergoes steady oscillations thereafter. However, drop breakup is the consequence if the forcing amplitude exceeds a critical value. Over a wide range of amplitudes above this critical value, drop ejection from the rod occurs during the second oscillation period from the commencement of rod motion. Remarkably, the shape of the interface at breakup and the volume of the primary drop formed are insensitive to changes in forcing amplitude. The interface shape at times close to and at breakup is a multi-valued function of distance measured along the rod axis and hence cannot be described by recently popularized one-dimensional approximations. The computations show that drop ejection occurs without the formation of a long neck. Therefore, this method of drop formation holds promise of preventing formation of undesirable satellite droplets.

  3. Characterization of Detector Response for PROSPECT - A Precision Reactor Oscillation and SPECTrum Measurement

    NASA Astrophysics Data System (ADS)

    Goddard, Brian; Dolinski, Michelle; Prospect Collaboration

    2015-10-01

    Recently, several experiments have reported an approximately 5% deficit of antineutrinos from nuclear reactors when the measured flux is compared with that predicted by current nuclear models. This is termed the ``Reactor Antineutrino Anomaly''. Furthermore, the predicted shape of the antineutrino spectrum is not in agreement with measurements from those experiments. The PROSPECT (Precision Reactor Oscillation and SPECTrum Measurement) collaboration plans to investigate this anomaly and constrain the shape of the spectrum with a high precision, short baseline (7-20m) measurement of the antineutrino spectrum from Oak Ridge National Laboratory's High Flux Isotope Reactor (HFIR) which will include a search for sterile neutrinos as one possible solution to the anomaly. PROSPECT will utilize a segmented, lithium-loaded liquid scintillator detector and is taking a phased approach to detector design by building progressively larger prototypes of this final detector with several prototypes already constructed and taking data. This poster will report on the ongoing analysis of the detector response of these prototypes including aspects such as position reconstruction, energy resolution, and pulse shape discrimination.

  4. Second International Workshop on Harmonic Oscillators

    NASA Technical Reports Server (NTRS)

    Han, Daesoo (Editor); Wolf, Kurt Bernardo (Editor)

    1995-01-01

    The Second International Workshop on Harmonic Oscillators was held at the Hotel Hacienda Cocoyoc from March 23 to 25, 1994. The Workshop gathered 67 participants; there were 10 invited lecturers, 30 plenary oral presentations, 15 posters, and plenty of discussion divided into the five sessions of this volume. The Organizing Committee was asked by the chairman of several Mexican funding agencies what exactly was meant by harmonic oscillators, and for what purpose the new research could be useful. Harmonic oscillators - as we explained - is a code name for a family of mathematical models based on the theory of Lie algebras and groups, with applications in a growing range of physical theories and technologies: molecular, atomic, nuclear and particle physics; quantum optics and communication theory.

  5. Oscillating fluid power generator

    DOEpatents

    Morris, David C

    2014-02-25

    A system and method for harvesting the kinetic energy of a fluid flow for power generation with a vertically oriented, aerodynamic wing structure comprising one or more airfoil elements pivotably attached to a mast. When activated by the moving fluid stream, the wing structure oscillates back and forth, generating lift first in one direction then in the opposite direction. This oscillating movement is converted to unidirectional rotational movement in order to provide motive power to an electricity generator. Unlike other oscillating devices, this device is designed to harvest the maximum aerodynamic lift forces available for a given oscillation cycle. Because the system is not subjected to the same intense forces and stresses as turbine systems, it can be constructed less expensively, reducing the cost of electricity generation. The system can be grouped in more compact clusters, be less evident in the landscape, and present reduced risk to avian species.

  6. A novel photonic oscillator

    NASA Technical Reports Server (NTRS)

    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.

  7. High frequency nanotube oscillator

    DOEpatents

    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.

  8. Quasioptical Josephson Oscillator

    NASA Astrophysics Data System (ADS)

    Wengler, Michael J.

    1994-09-01

    The Quasioptical Josephson Oscillator (QJO) is a 2-D array of between 100 and 1,000,000 Josephson junctions, each at the center of a small dipole antenna. HYPRES, Inc. of Elmsford, NY has fabricated test chips which have demonstrated 0.35 microwatts radiation at 190 CHz in one case, and 0.7 microwatts radiation at 345 GHz in another case. A significant understanding of the 2-D oscillators was developed through theoretical and numerical calculations.

  9. Ultrastable Multigigahertz Photonic Oscillator

    NASA Technical Reports Server (NTRS)

    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.

  10. Classical and quantum Kummer shape algebras

    NASA Astrophysics Data System (ADS)

    Odzijewicz, A.; Wawreniuk, E.

    2016-07-01

    We study a family of integrable systems of nonlinearly coupled harmonic oscillators on the classical and quantum levels. We show that the integrability of these systems follows from their symmetry characterized by algebras, here called Kummer shape algebras. The resolution of identity for a wide class of reproducing kernels is found. A number of examples, illustrating this theory, are also presented.

  11. Oscillating asymmetric dark matter

    SciTech Connect

    Tulin, Sean; Yu, Hai-Bo; Zurek, Kathryn M. E-mail: haiboyu@umich.edu

    2012-05-01

    We study the dynamics of dark matter (DM) particle-antiparticle oscillations within the context of asymmetric DM. Oscillations arise due to small DM number-violating Majorana-type mass terms, and can lead to recoupling of annihilation after freeze-out and washout of the DM density. Asymmetric DM oscillations 'interpolate' between symmetric and asymmetric DM freeze-out scenarios, and allow for a larger DM model-building parameter space. We derive the density matrix equations for DM oscillations and freeze-out from first principles using nonequilibrium field theory, and our results are qualitatively different than in previous studies. DM dynamics exhibits particle-vs-antiparticle 'flavor' effects, depending on the interaction type, analogous to neutrino oscillations in a medium. 'Flavor-sensitive' DM interactions include scattering or annihilation through a new vector boson, while 'flavor-blind' interactions include scattering or s-channel annihilation through a new scalar boson. In particular, we find that flavor-sensitive annihilation does not recouple when coherent oscillations begin, and that flavor-blind scattering does not lead to decoherence.

  12. Periodically oscillating plasma sphere

    SciTech Connect

    Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar

    2005-05-15

    The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

  13. Oscillating edge-flames

    NASA Astrophysics Data System (ADS)

    Buckmaster, J.; Zhang, Yi

    1999-09-01

    It has been known for some years that when a near-limit flame spreads over a liquid pool of fuel, the edge of the flame can oscillate. It is also known that when a near-asphyxiated candle-flame burns in zero gravity, the edge of the (hemispherical) flame can oscillate violently prior to extinction. We propose that these oscillations are nothing more than a manifestation of the large Lewis number instability well known in chemical reactor studies and in combustion studies, one that is exacerbated by heat losses. As evidence of this we examine an edge-flame confined within a fuel-supply boundary and an oxygen-supply boundary, anchored by a discontinuity in data at the fuel-supply boundary. We show that when the Lewis number of the fuel is 2, and the Lewis number of the oxidizer is 1, oscillations of the edge occur when the Damköhler number is reduced below a critical value. During a single oscillation period there is a short premixed propagation stage and a long diffusion stage, behaviour that has been observed in flame spread experiments. Oscillations do not occur when both Lewis numbers are equal to 1.

  14. Rocket Engine Oscillation Diagnostics

    NASA Technical Reports Server (NTRS)

    Nesman, Tom; Turner, James E. (Technical Monitor)

    2002-01-01

    Rocket engine oscillating data can reveal many physical phenomena ranging from unsteady flow and acoustics to rotordynamics and structural dynamics. Because of this, engine diagnostics based on oscillation data should employ both signal analysis and physical modeling. This paper describes an approach to rocket engine oscillation diagnostics, types of problems encountered, and example problems solved. Determination of design guidelines and environments (or loads) from oscillating phenomena is required during initial stages of rocket engine design, while the additional tasks of health monitoring, incipient failure detection, and anomaly diagnostics occur during engine development and operation. Oscillations in rocket engines are typically related to flow driven acoustics, flow excited structures, or rotational forces. Additional sources of oscillatory energy are combustion and cavitation. Included in the example problems is a sampling of signal analysis tools employed in diagnostics. The rocket engine hardware includes combustion devices, valves, turbopumps, and ducts. Simple models of an oscillating fluid system or structure can be constructed to estimate pertinent dynamic parameters governing the unsteady behavior of engine systems or components. In the example problems it is shown that simple physical modeling when combined with signal analysis can be successfully employed to diagnose complex rocket engine oscillatory phenomena.

  15. Nanoconstriction-based spin-Hall nano-oscillator

    NASA Astrophysics Data System (ADS)

    Demidov, V. E.; Urazhdin, S.; Zholud, A.; Sadovnikov, A. V.; Demokritov, S. O.

    2014-10-01

    We experimentally demonstrate magnetic nano-oscillators driven by pure spin current produced by the spin Hall effect in a bow tie-shaped nanoconstriction. These devices exhibit single-mode auto-oscillation and generate highly-coherent electronic microwave signals with a significant power and the spectral linewidth as low as 6.2 MHz at room temperature. The proposed simple and flexible device geometry is amenable to straightforward implementation of advanced spintronic structures such as chains of mutually coupled spin-Hall nano-oscillators.

  16. Nanoconstriction-based spin-Hall nano-oscillator

    SciTech Connect

    Demidov, V. E.; Urazhdin, S.; Zholud, A.; Sadovnikov, A. V.; Demokritov, S. O.

    2014-10-27

    We experimentally demonstrate magnetic nano-oscillators driven by pure spin current produced by the spin Hall effect in a bow tie-shaped nanoconstriction. These devices exhibit single-mode auto-oscillation and generate highly-coherent electronic microwave signals with a significant power and the spectral linewidth as low as 6.2 MHz at room temperature. The proposed simple and flexible device geometry is amenable to straightforward implementation of advanced spintronic structures such as chains of mutually coupled spin-Hall nano-oscillators.

  17. Characterization of stationary and nonstationary behavior in gyrotron oscillators.

    PubMed

    Chang, T H; Chen, S H; Barnett, L R; Chu, K R

    2001-08-01

    The transition from the stationary state to a sequence of nonstationary states in the gyromonotron oscillator is experimentally characterized for the first time. We have also demonstrated the stationary operation of a gyrotron backward-wave oscillator at a beam current far in excess of the generally predicted nonstationary threshold. This difference in nonlinear behavior has been investigated and shown to be fundamental with a comparative analysis of the feedback mechanisms, energy deposition profiles, and field shaping processes involved in these two types of oscillations. PMID:11497832

  18. Sensitivity of two-dimensional flow past transversely oscillating cylinder to streamwise cylinder oscillations

    NASA Astrophysics Data System (ADS)

    Peppa, Sofia; Triantafyllou, George S.

    2016-03-01

    In this paper we study the sensitivity of flow past a transversely oscillating cylinder to streamwise harmonic perturbations. The value of the Reynolds number is equal to 150, for which the flow is two-dimensional. We start with a transversely oscillating cylinder and then impose a small streamwise (in-line) perturbation with a frequency equal to twice the transverse oscillation frequency. The cylinder is thus following an eight-shaped trajectory, which can be traversed in a counter-clockwise or clockwise direction. For low values of the in-line amplitude, we find for the counter-clockwise mode that the power transfer from the fluid to the structure increases with the amplitude of oscillation in the streamwise direction, even though the magnitude of the fluctuations of the forces is decreased. For the clockwise mode of motion we observe the reverse trend, i.e., the power transfer from the fluid to the structure is decreased, even though the magnitude of the fluctuations of the forces is increased. It is shown that the variation of the power transfer in both types of motion is due primarily to the variation of the phase between the transverse oscillation of the cylinder and the vortex lift force as a result of the in-line oscillation. For higher values of the streamwise amplitude, the contribution of the fluctuating drag to the power transfer also becomes important, especially for the counter-clockwise mode. Both modes of oscillation are characterized by the presence of the third harmonic in the spectrum of the lift force as the in-line oscillation is increased and by the appearance of a combination of single vortices on the one side of the wake, and vortex pairs on the other side.

  19. The active-bridge oscillator

    SciTech Connect

    Wessendorf, K.O.

    1998-07-01

    This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is ab ridge-type oscillator design that is easly to design and overcomes many of the operational and design difficulties associated with standard bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. for this and other reasons, bridge oscilaltors are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator.

  20. Tristability and self-oscillations in a double resonator system

    NASA Astrophysics Data System (ADS)

    Velikovich, A. L.; Golubev, G. P.; Golubchenko, V. P.; Luchinsky, D. G.

    1991-01-01

    A system consisting of two coupled Fabry-Perot resonators, one of them nonlinear, with an additional feedback between them is studied experimentally and theoretically. The dependence between the phase shift δφ of the resonator 2 and the laser-induced thermal load Q applied to the resonator 1 is essentially nonlinear. This nonlinearity of the additional feedback in the double resonator system is shown to make possible its self-oscillations and the existence of the tristable 8-shaped hysteresis curves. The frequencies of the observed self-oscillations are in the range from 100 Hz to 100 kHz, their shapes varying from sinusoidal to square and sawtooth.

  1. Neutrino Oscillation Physics

    SciTech Connect

    Kayser, Boris

    2012-06-01

    To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures. Neutrinos and photons are by far the most abundant elementary particles in the universe. Thus, if we would like to comprehend the universe, we must understand the neutrinos. Of course, studying the neutrinos is challenging, since the only known forces through which these electrically-neutral leptons interact are the weak force and gravity. Consequently, interactions of neutrinos in a detector are very rare events, so that very large detectors and intense neutrino sources are needed to make experiments feasible. Nevertheless, we have confirmed that the weak interactions of neutrinos are correctly described by the Standard Model (SM) of elementary particle physics. Moreover, in the last 14 years, we have discovered that neutrinos have nonzero masses, and that leptons mix. These discoveries have been based on the observation that neutrinos can change from one 'flavor' to another - the phenomenon known as neutrino oscillation. We shall explain the physics of neutrino oscillation, deriving the probability of oscillation in a new way. We shall also provide a very brief guide to references that can be used to study some major neutrino-physics topics other than neutrino oscillation.

  2. Nuclear magnetic resonance studies of guest species in clathrate hydrates: Line-shape anisotropies, chemical shifts, and the determination of cage occupancy ratios and hydration numbers

    SciTech Connect

    Collins, M.J.; Ratcliffe, C.I.; Ripmeester, J.A. )

    1990-01-11

    NMR spectra of the guest molecules PH{sub 3}, H{sub 2}Se, D{sub 2}Se, D{sub 2}S, CD{sub 3}F, CD{sub 3}Cl, CD{sub 3}Br, C{sub 2}D{sub 2}, and C{sub 2}D{sub 4} in their structure I clathrate hydrates have been obtained by use of {sup 2}H, {sup 19}F, {sup 31}P, and {sup 77}Se nuclei. Components due to guests in the small and large cages have been distinguished by using isotropic chemical shift and static line-shape anisotropy differences. Low-temperature magic angle spinning was used in some cases to resolve the two components. Guests in the small cages are invariably found to have a lower field isotropic shift than those in the large cage. The static line shapes are isotropic for guests in the small spherical cages, whereas in the large oblate cages they have a residual anisotropy. Relative cage occupancy ratios {theta}{sub S}/{theta}{sub L} have been obtained from the observed NMR intensities, and together with similar results from previous NMR studies, these have been used to derive hydration numbers. This represents a new and nondestructive method of determining structure I hydrate compositions.

  3. Equilibrium Shaping

    NASA Astrophysics Data System (ADS)

    Izzo, Dario; Petazzi, Lorenzo

    2006-08-01

    We present a satellite path planning technique able to make identical spacecraft aquire a given configuration. The technique exploits a behaviour-based approach to achieve an autonomous and distributed control over the relative geometry making use of limited sensorial information. A desired velocity is defined for each satellite as a sum of different contributions coming from generic high level behaviours: forcing the final desired configuration the behaviours are further defined by an inverse dynamic calculation dubbed Equilibrium Shaping. We show how considering only three different kind of behaviours it is possible to acquire a number of interesting formations and we set down the theoretical framework to find the entire set. We find that allowing a limited amount of communication the technique may be used also to form complex lattice structures. Several control feedbacks able to track the desired velocities are introduced and discussed. Our results suggest that sliding mode control is particularly appropriate in connection with the developed technique.

  4. Periodic orbits in glycolytic oscillators: from elliptic orbits to relaxation oscillations.

    PubMed

    Roy, T; Bhattacharjee, J K; Mallik, A K

    2011-02-01

    We consider the Sel'kov model of glycolytic oscillator for a quantitative study of the limit cycle oscillations in the system. We identify a region of parameter space where perturbation theory holds and use both Linstedt Poincaré technique and harmonic balance to obtain the shape and frequency of the limit cycle. The agreement with the numerically obtained result is excellent. We also find a different extreme, where the limit cycle is of the relaxation oscillator variety, has a large time period and it is seen that, as a particular parameter in the model is varied, the time period increases indefinitely. We characterize this divergence numerically. A calculational method is devised to capture the divergence approximately. PMID:21359930

  5. A New Neutrino Oscillation

    SciTech Connect

    Parke, Stephen J.; /Fermilab

    2011-07-01

    Starting in the late 1960s, neutrino detectors began to see signs that neutrinos, now known to come in the flavors electron ({nu}{sub e}), muon ({nu}{sub {mu}}), and tau ({nu}{sub {tau}}), could transform from one flavor to another. The findings implied that neutrinos must have mass, since massless particles travel at the speed of light and their clocks, so to speak, don't tick, thus they cannot change. What has since been discovered is that neutrinos oscillate at two distinct scales, 500 km/GeV and 15,000 km/GeV, which are defined by the baseline (L) of the experiment (the distance the neutrino travels) divided by the neutrino energy (E). Neutrinos of one flavor can oscillate into neutrinos of another flavor at both L/E scales, but the amplitude of these oscillations is different for the two scales and depends on the initial and final flavor of the neutrinos. The neutrino states that propogate unchanged in time, the mass eigenstates {nu}1, {nu}2, {nu}3, are quantum mechanical mixtures of the electron, muon, and tau neutrino flavors, and the fraction of each flavor in a given mass eigenstate is controlled by three mixing angles and a complex phase. Two of these mixing angles are known with reasonable precision. An upper bound exists for the third angle, called {theta}{sub 13}, which controls the size of the muon neutrino to electron neutrino oscillation at an L/E of 500 km/GeV. The phase is completely unknown. The existence of this phase has important implications for the asymmetry between matter and antimatter we observe in the universe today. Experiments around the world have steadily assembled this picture of neutrino oscillation, but evidence of muon neutrino to electron neutrino oscillation at 500 km/GeV has remained elusive. Now, a paper from the T2K (Tokai to Kamioka) experiment in Japan, reports the first possible observation of muon neutrinos oscillating into electron neutrinos at 500 km/GeV. They see 6 candidate signal events, above an expected background

  6. Forced spaser oscillations

    NASA Astrophysics Data System (ADS)

    Lisyansky, Alexander A.; Andrianov, Eugeney S.; Dorofeenko, Alexander V.; Pukhov, Alexander A.; Vinogradov, Alexey P.

    2012-10-01

    We study oscillations of a spaser driven by an external optical wave. When the frequency of the external field is shifted from the frequency of an autonomous spaser, the spaser exhibits stochastic oscillations at low field intensity. The plasmon oscillations lock to the frequency of the external field only when the field amplitude exceeds a threshold value. We find a region of external field amplitude and the frequency detuning (the Arnold tongue) for which the spaser becomes synchronized with the external wave. We obtain the conditions upon the amplitude and frequency of the external field (the curve of compensation) at which the spaser's dipole moment oscillates with a phase shift of π relatively to the external wave. For these values of the amplitude and frequency, the loss in the metal nanoparticles within the spaser is exactly compensated for by the gain. It is expected that if these conditions are not satisfied, then due to loss or gain of energy, the amplitude of the wave travelling along the system of spasers either tends to the curve of compensation or leave the Arnold tongue. We also consider cooperative phenomena showing that in a chain of interacting spasers, depending on the values of the coupling constants, either all spasers oscillate in phase or a nonlinear autowave travels in the system. In the latter scenario, the traveling wave is harmonic, unlike excitations in other nonlinear systems. Due to the nonlinear nature of the system, any initial distribution of spaser states evolves into one of these steady states.

  7. Oscillations of soap bubbles

    NASA Astrophysics Data System (ADS)

    Kornek, U.; Müller, F.; Harth, K.; Hahn, A.; Ganesan, S.; Tobiska, L.; Stannarius, R.

    2010-07-01

    Oscillations of droplets or bubbles of a confined fluid in a fluid environment are found in various situations in everyday life, in technological processing and in natural phenomena on different length scales. Air bubbles in liquids or liquid droplets in air are well-known examples. Soap bubbles represent a particularly simple, beautiful and attractive system to study the dynamics of a closed gas volume embedded in the same or a different gas. Their dynamics is governed by the densities and viscosities of the gases and by the film tension. Dynamic equations describing their oscillations under simplifying assumptions have been well known since the beginning of the 20th century. Both analytical description and numerical modeling have made considerable progress since then, but quantitative experiments have been lacking so far. On the other hand, a soap bubble represents an easily manageable paradigm for the study of oscillations of fluid spheres. We use a technique to create axisymmetric initial non-equilibrium states, and we observe damped oscillations into equilibrium by means of a fast video camera. Symmetries of the oscillations, frequencies and damping rates of the eigenmodes as well as the coupling of modes are analyzed. They are compared to analytical models from the literature and to numerical calculations from the literature and this work.

  8. The Kramers Oscillator Revisited

    NASA Astrophysics Data System (ADS)

    Arnold, Ludwig; Imkeller, Peter

    In their 1993 paper [14], Schimansky-Geier and Herze1 discovered numerically that the Kramers oscillator (which is identical with the Duffing oscillator forced by additive white noise) has a positive top Lyapunov exponent in the low damping regime. In this paper, we study the Kramers oscillator from the point of view of random dynamical systems. In particular, we confirm the findings in the paper [14] about the Lyapunov exponent by performing more precise simulations, revealing that the Lyapunov exponent is positive up to a critical value of the damping, from which on it remains negative. We then show that the Kramers oscillator has a global random attractor which in the stable regime (large damping) is just a random point and in the unstable regime (small damping) has very complicated geometrical structure. In the lat-ter case the invariant measure supported by the attractor is a Sinai-Ruelle-Bowen measure with positive entropy. The Kramers oscillator hence undergoes a stochastic bifurcation at the critical value of the damping Parameter.

  9. Oscillations following periodic reinforcement.

    PubMed

    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. PMID:18992793

  10. Combustor oscillation pressure stabilizer

    SciTech Connect

    Gemmen, R.S.; Richards, G.A.; Yip, M.T.J.; Robey, E.; Cully, S.R.; Addis, R.E.

    1996-12-31

    In accordance with the objective of the present invention, the active control of unsteady combustion induced oscillations in a combustion chamber fired by a suitable fuel and oxidizer mixture, such as a hydrocarbon fuel and air mixture, is provided by restructuring and moving the position of the main flame front and thereby increasing the transport time and displacing the pressure wave further away from the in-phase relationship with the periodic heat release. The restructuring and repositioning of the main flame are achieved by utilizing a pilot flame which is pulsed at a predetermined frequency corresponding to less than about one-half the frequency of the combustion oscillation frequency with the duration of each pulse being sufficient to produce adequate secondary thermal energy to restructure the main flame and thereby decouple the heat release from the acoustic coupling so as to lead to a reduction in the dynamic pressure amplitude. The pulsating pilot flame produces a relatively small and intermittently existing flame front in the combustion zone that is separate from the oscillating main flame front but which provides the thermal energy necessary to effectively reposition the location of the oscillating main flame front out of the region in the combustion zone where the acoustic coupling can occur with the main flame and thereby effectively altering the oscillation-causing phase relationship with the heat of combustion.

  11. Alpha-particles as probes of nuclear shape in the rare earths and structure effects on proton emission in the mass 80 region

    SciTech Connect

    Sarantites, D.G.; Nicolis, N.G.; Abenante, V.; Majka, Z.; Semkow, T.M. . Dept. of Internal Medicine); Baktash, C.; Beene, J.R.; Garcia-Bermudez, G.; Halbert, M.L.; Hensley, D.C.; Johnson, N.R.; Lee, I.Y.; McGowan, F.K.; Riley, M.A.; Virtanen, A. ); Griffin, H.C. )

    1989-01-01

    Low emission barriers and large subbarrier anisotropies in the alpha-particle decay with respect to the spin direction, of Sn and rare earth compound nuclei, are examined in the light of recent calculations incorporating deformation. For the rare earth systems deformation which increases with spin is necessary to explain the data. Energy spectra and angular correlations of evaporated protons from the {sup 52}Cr({sup 34}S, 2p2n){sup 82}Sr reaction were measured in coincidence with discrete transition. Large changes in the shape of the proton spectra were observed when high spin states in different rotation al bands are populated. These effects cannot be explained by phase space arguments in the deexcitation process. They are interpreted as due to near-yrast to near-yrast stretched proton emission, which preferentially populates the yrast band by subbarrier protons. 20 refs., 8 figs.

  12. Digital numerically controlled oscillator

    NASA Technical Reports Server (NTRS)

    Cellier, A.; Huey, D. C.; Ma, L. N. (Inventor)

    1980-01-01

    The frequency and phase of an output signal from an oscillator circuit are controlled with accuracy by a digital input word. Positive and negative alterations in output frequency are both provided for by translating all values of input words so that they are positive. The oscillator reference frequency is corrected only in one direction, by adding phase to the output frequency of the oscillator. The input control word is translated to a single algebraic sign and the digital 1 is added thereto. The translated input control word is then accumulated. A reference clock signal having a frequency at an integer multiple of the desired frequency of the output signal is generated. The accumulated control word is then compared with a threshold level. The output signal is adjusted in a single direction by dividing the frequency of the reference clock signal by a first integer or by an integer different from the first integer.

  13. The Fastest Quasiperiodic Oscillations

    NASA Astrophysics Data System (ADS)

    Kaaret, Philip

    Quasi-periodic oscillations (QPOs) at frequencies near 1000 Hz have been detected from a umber of neutron star x-ray binaries using RXTE. These fast oscillations are likely associated with rbital motion very close to the neutron star and and, thus, give us information about the behavior of the accretion disk in the strong gravitational field near the neutron star. The oscillation frequencies can also be used to place constraints on the properties of the neutron stars with the highest detected frequencies being the most constraining. We propose TOOs observations of selected neutron star x-ray binaries when found to be in states likely to produce kHz QPOs with frequencies exceeding 1200 Hz.

  14. Magnetic vortex oscillators

    NASA Astrophysics Data System (ADS)

    Hrkac, Gino; Keatley, Paul S.; Bryan, Matthew T.; Butler, Keith

    2015-11-01

    The magnetic vortex has sparked the interest of the academic and industrial communities over the last few decades. From their discovery in the 1970s for bubble memory devices to their modern application as radio frequency oscillators, magnetic vortices have been adopted to modern telecommunication and sensor applications. Basic properties of vortex structures in the static and dynamic regime, from a theoretical and experimental point of view, are presented as well as their application in spin torque driven nano-pillar and magnetic tunnel junction devices. Single vortex excitations and phase locking phenomena of coupled oscillators are discussed with an outlook of vortex oscillators in magnetic hybrid structures with imprinted domain confinement and dynamic encryption devices.

  15. Universal fitting formulae for baryon oscillation surveys

    NASA Astrophysics Data System (ADS)

    Blake, Chris; Parkinson, David; Bassett, Bruce; Glazebrook, Karl; Kunz, Martin; Nichol, Robert C.

    2006-01-01

    The next generation of galaxy surveys will attempt to measure the baryon oscillations in the clustering power spectrum with high accuracy. These oscillations encode a preferred scale which may be used as a standard ruler to constrain cosmological parameters and dark energy models. In this paper we present simple analytical fitting formulae for the accuracy with which the preferred scale may be determined in the tangential and radial directions by future spectroscopic and photometric galaxy redshift surveys. We express these accuracies as a function of survey parameters such as the central redshift, volume, galaxy number density and (where applicable) photometric redshift error. These fitting formulae should greatly increase the efficiency of optimizing future surveys, which requires analysis of a potentially vast number of survey configurations and cosmological models. The formulae are calibrated using a grid of Monte Carlo simulations, which are analysed by dividing out the overall shape of the power spectrum before fitting a simple decaying sinusoid to the oscillations. The fitting formulae reproduce the simulation results with a fractional scatter of 7 per cent (10 per cent) in the tangential (radial) directions over a wide range of input parameters. We also indicate how sparse-sampling strategies may enhance the effective survey area if the sampling scale is much smaller than the projected baryon oscillation scale.

  16. Synchronization of coupled Boolean phase oscillators

    NASA Astrophysics Data System (ADS)

    Rosin, David P.; Rontani, Damien; Gauthier, Daniel J.

    2014-04-01

    We design, characterize, and couple Boolean phase oscillators that include state-dependent feedback delay. The state-dependent delay allows us to realize an adjustable coupling strength, even though only Boolean signals are exchanged. Specifically, increasing the coupling strength via the range of state-dependent delay leads to larger locking ranges in uni- and bidirectional coupling of oscillators in both experiment and numerical simulation with a piecewise switching model. In the unidirectional coupling scheme, we unveil asymmetric triangular-shaped locking regions (Arnold tongues) that appear at multiples of the natural frequency of the oscillators. This extends observations of a single locking region reported in previous studies. In the bidirectional coupling scheme, we map out a symmetric locking region in the parameter space of frequency detuning and coupling strength. Because of the large scalability of our setup, our observations constitute a first step towards realizing large-scale networks of coupled oscillators to address fundamental questions on the dynamical properties of networks in a new experimental setting.

  17. Gamma Oscillation in Schizophrenia

    PubMed Central

    O'Donnell, Brian F.; Youn, Soyoung; Kwon, Jun Soo

    2011-01-01

    Dysfunctional neural circuitry has been found to be involved in abnormalities of perception and cognition in patients with schizophrenia. Gamma oscillations are essential for integrating information within neural circuits and have therefore been associated with many perceptual and cognitive processes in healthy human subjects and animals. This review presents an overview of the neural basis of gamma oscillations and the abnormalities in the GABAergic interneuronal system thought to be responsible for gamma-range deficits in schizophrenia. We also review studies of gamma activity in sensory and cognitive processes, including auditory steady state response, attention, object representation, and working memory, in animals, healthy humans and patients with schizophrenia. PMID:22216037

  18. Micromechanical Oscillating Mass Balance

    NASA Technical Reports Server (NTRS)

    Altemir, David A. (Inventor)

    1997-01-01

    A micromechanical oscillating mass balance and method adapted for measuring minute quantities of material deposited at a selected location, such as during a vapor deposition process. The invention comprises a vibratory composite beam which includes a dielectric layer sandwiched between two conductive layers. The beam is positioned in a magnetic field. An alternating current passes through one conductive layers, the beam oscillates, inducing an output current in the second conductive layer, which is analyzed to determine the resonant frequency of the beam. As material is deposited on the beam, the mass of the beam increases and the resonant frequency of the beam shifts, and the mass added is determined.

  19. Coupled opto-electronic oscillator

    NASA Technical Reports Server (NTRS)

    Yao, X. Steve (Inventor); Maleki, Lute (Inventor)

    1999-01-01

    A coupled opto-electronic oscillator that directly couples a laser oscillation with an electronic oscillation to simultaneously achieve a stable RF oscillation at a high frequency and ultra-short optical pulsation by mode locking with a high repetition rate and stability. Single-mode selection can be achieved even with a very long opto-electronic loop. A multimode laser can be used to pump the electronic oscillation, resulting in a high operation efficiency. The optical and the RF oscillations are correlated to each other.

  20. Physical properties, structure, and shape of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident derived from soil, bamboo and shiitake mushroom measurements.

    PubMed

    Niimura, Nobuo; Kikuchi, Kenji; Tuyen, Ninh Duc; Komatsuzaki, Masakazu; Motohashi, Yoshinobu

    2015-01-01

    We conducted an elution experiment with contaminated soils using various aqueous reagent solutions and autoradiography measurements of contaminated bamboo shoots and shiitake mushrooms to determine the physical and chemical characteristics of radioactive Cs from the Fukushima Daiichi Nuclear Power Plant accident. Based on our study results and data in the literature, we conclude that the active Cs emitted by the accident fell to the ground as granular non-ionic materials. Therefore, they were not adsorbed or trapped by minerals in the soil, but instead physically adhere to the rough surfaces of the soil mineral particles. Granular Cs* can be transferred among media, such as soils and plants. The physical properties and dynamic behavior of the granular Cs* is expected to be helpful in considering methods for decontamination of soil, litter, and other media. PMID:24445055

  1. Unsteady flow computation of oscillating flexible wings

    NASA Technical Reports Server (NTRS)

    Kandil, Osama A.; Chuang, H. Andrew; Salman, Ahmed A.

    1990-01-01

    The problem of unsteady flow around flexible wings is solved using the unsteady, compressible, thin-layer Navier-Stokes equations in conjunction with the unsteady, linearized, Navier-displacement equations. Starting with the initial shape of the wing, the Navier-Stokes equations are solved on an initial structured grid to obtain the steady-flow solution which is used for the initial conditions. The forced deformation motion of the wing boundaries is then applied, and the problem is solved accurately in time. During the time-accurate stepping, the Navier-displacement equations are used to solve for the grid deformation and sequently, the Navier-Stokes equations are used to solve for the flowfield. Two applications are presented; the first is for a pulsating oscillation of a bending-mode airfoil in transonic flow, and the second is for a bending-mode oscillation of a sharp-edged delta wing in supersonic flow.

  2. Oscillator Phase Noise: A 50-Year Review.

    PubMed

    Leeson, David B

    2016-08-01

    Fifty years ago emerging requirements in oscillator applications led to the 1964 IEEE-NASA Symposium on Short-term Frequency Stability. Following that, IEEE Technical Committee 14.7 was established to unify time- and frequency-domain definitions of frequency stability. I had the good fortune to participate and contribute as a member of the symposium program committee and the IEEE committee. This paper is a personal retrospective of events that are said to have shaped our field: the 1964 Symposium, the 1966 Proc. IEEE special issue on frequency stability we edited (with comments on my oscillator-model paper), and our 1971 paper, "Characterization of Frequency Stability," written as a basis for IEEE STD 1139. PMID:27164585

  3. Nanoparticle Oscillations and Fronts

    SciTech Connect

    Lagzi, Istvan; Kowalczyk, Bartlomiej; Wang, Dawei; Grzybowski, Bartosz A.

    2010-09-30

    Chemical oscillations can be coupled to the dynamic self-assembly of nanoparticles. Periodic pH changes translate into protonation and deprotonation of the ligands that stabilize the nanoparticles, thus altering repulsive and attractive interparticle forces. In a continuous stirred-tank reactor, rhythmic aggregation and dispersion is observed; in spatially distributed media, propagation of particle aggregation fronts is seen.

  4. Voltage-Controlled Oscillator

    NASA Technical Reports Server (NTRS)

    1995-01-01

    Integrated Component Systems, Inc. incorporated information from a NASA Tech Briefs article into a voltage-controlled oscillator it designed for a customer. The company then applied the technology to its series of phase-locked loop synthesizers, which offer superior phase noise performance.

  5. Coupled Oscillators with Chemotaxis

    NASA Astrophysics Data System (ADS)

    Sawai, Satoshi; Aizawa, Yoji

    1998-08-01

    A simple coupled oscillator system with chemotaxis is introducedto study morphogenesis of cellular slime molds. The modelsuccessfuly explains the migration of pseudoplasmodium which hasbeen experimentally predicted to be lead by cells with higherintrinsic frequencies. Results obtained predict that its velocityattains its maximum value in the interface region between totallocking and partial locking and also suggest possible rolesplayed by partial synchrony during multicellular development.

  6. Oscillating Reactions: Two Analogies

    ERIC Educational Resources Information Center

    Petruševski, Vladimir M.; Stojanovska, Marina I.; Šoptrajanov, Bojan T.

    2007-01-01

    Oscillating chemical reactions are truly spectacular phenomena, and demonstrations are always appreciated by the class. However, explaining such reactions to high school or first-year university students is problematic, because it may seem that no acceptable explanation is possible unless the students have profound knowledge of both physical…

  7. Relativistic harmonic oscillator revisited

    SciTech Connect

    Bars, Itzhak

    2009-02-15

    The familiar Fock space commonly used to describe the relativistic harmonic oscillator, for example, as part of string theory, is insufficient to describe all the states of the relativistic oscillator. We find that there are three different vacua leading to three disconnected Fock sectors, all constructed with the same creation-annihilation operators. These have different spacetime geometric properties as well as different algebraic symmetry properties or different quantum numbers. Two of these Fock spaces include negative norm ghosts (as in string theory), while the third one is completely free of ghosts. We discuss a gauge symmetry in a worldline theory approach that supplies appropriate constraints to remove all the ghosts from all Fock sectors of the single oscillator. The resulting ghost-free quantum spectrum in d+1 dimensions is then classified in unitary representations of the Lorentz group SO(d,1). Moreover, all states of the single oscillator put together make up a single infinite dimensional unitary representation of a hidden global symmetry SU(d,1), whose Casimir eigenvalues are computed. Possible applications of these new results in string theory and other areas of physics and mathematics are briefly mentioned.

  8. A simple violin oscillator

    NASA Technical Reports Server (NTRS)

    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.

  9. Wein bridge oscillator circuit

    NASA Technical Reports Server (NTRS)

    Lipoma, P. C.

    1971-01-01

    Circuit with minimum number of components provides stable outputs of 2 to 8 volts at frequencies of .001 to 100 kHz. Oscillator exhibits low power consumption, portability, simplicity, and drive capability, it has application as loudspeaker tester and audible alarm, as well as in laboratory and test generators.

  10. Superordinate Shape Classification Using Natural Shape Statistics

    ERIC Educational Resources Information Center

    Wilder, John; Feldman, Jacob; Singh, Manish

    2011-01-01

    This paper investigates the classification of shapes into broad natural categories such as "animal" or "leaf". We asked whether such coarse classifications can be achieved by a simple statistical classification of the shape skeleton. We surveyed databases of natural shapes, extracting shape skeletons and tabulating their parameters within each…

  11. Prospects for detecting supernova neutrino flavor oscillations

    NASA Astrophysics Data System (ADS)

    Fuller, George M.; Haxton, Wick C.; McLaughlin, Gail C.

    1999-04-01

    The neutrinos from a type II supernova provide perhaps our best opportunity to probe cosmologically interesting muon and/or tauon neutrino masses. This is because matter enhanced neutrino oscillations can lead to an anomalously hot νe spectrum, and thus to enhanced charged current cross sections in terrestrial detectors. Two recently proposed supernova neutrino observatories, OMNIS and LAND, will detect neutrons spalled from target nuclei by neutral and charged current neutrino interactions. As this signal is not flavor specific, it is not immediately clear whether a convincing neutrino oscillation signal can be extracted from such experiments. To address this issue we examine the responses of a series of possible light and heavy mass targets, 9Be,23Na,35Cl, and 208Pb. We find that strategies for detecting oscillations which use only neutron count rates are problematic at best, even if cross sections are determined by ancillary experiments. Plausible uncertainties in supernova neutrino spectra tend to obscure rate enhancements due to oscillations. However, in the case of 208Pb, a signal emerges that is largely flavor specific and extraordinarily sensitive to the νe temperature, the emission of two neutrons. This signal and its flavor specificity are associated with the strength and location of the first-forbidden responses for neutral and charge current reactions, aspects of the 208Pb neutrino cross section that have not been discussed previously. Hadronic spin transfer experiments might be helpful in confirming some of the nuclear structure physics underlying our conclusions.

  12. Master oscillator stability requirements considerations

    SciTech Connect

    Schwarz, H.; Vancraeynest, J.

    1986-06-24

    This note attempts to point out some ideas about the required stability of the 476 MHz master oscillator, assuming that the phase noise of the oscillator is the only source of noise in the accelerator system.

  13. Orthogonal polynomials and deformed oscillators

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    In the example of the Fibonacci oscillator, we discuss the construction of oscillator-like systems associated with orthogonal polynomials. We also consider the question of the dimensions of the corresponding Lie algebras.

  14. The role of Pleistocene glaciations in shaping the evolution of polar and brown bears. Evidence from a critical review of mitochondrial and nuclear genome analyses.

    PubMed

    Hassanin, Alexandre

    2015-07-01

    In this report, I review recent molecular studies dealing with the origin and evolution of polar bears (Ursus maritimus), with special emphasis on their relationships with brown bears (U. arctos). On the basis of mitochondrial and nuclear data, different hypotheses have been proposed, including rapid morphological differentiation of U. maritimus, genetic introgression from U. arctos into U. maritimus, or inversely from U. maritimus into U. arctos, involving either male- or female-mediated gene flow. In the light of available molecular and eco-ethological data, I suggest, firstly, that all divergences among major clades of large bears can be linked to glacial periods, secondly, that polar bears diverged from brown bears before 530 thousand years ago (ka), during one of the three glacial marine isotope stages (MIS) 14, 15.2 or 16, and, thirdly, that genetic introgression had occurred from female polar bears into brown bear populations during at least two glacial periods, at 340 ± 10 ka (MIS 10) in western Europe, and at 155 ± 5 ka (MIS 6) on the ABC islands of southeastern Alaska, and probably also in Beringia and Ireland based on ancient DNA sequences. PMID:26026577

  15. Forced Oscillations for Hybrid Systems

    NASA Astrophysics Data System (ADS)

    Cheshankov, B.

    2009-11-01

    The hybrid system in the paper means a mechanical system which consists from two parts with different structure—a part with distributed parameters and a part with discrete parameters. More concrete the forced longitudinal oscillations of a rod connected with a simple oscillator are considered. The oscillations of the separate parts of the system are very well known. It turned out that the oscillations of this hybrid system propose some difficulties when investigating. The paper proposes an approach to overcome these difficulties.

  16. Friedel oscillations as a probe of fermionic quasiparticles

    NASA Astrophysics Data System (ADS)

    Dalla Torre, Emanuele G.; Benjamin, David; He, Yang; Dentelski, David; Demler, Eugene

    2016-05-01

    When immersed in a sea of electrons, local impurities give rise to density modulations known as Friedel oscillations. In spite of the generality of this phenomenon, the exact shape of these modulations is usually computed only for noninteracting electrons with a quadratic dispersion relation. In actual materials, Friedel oscillations are a viable way to access the properties of electronic quasiparticles, including their dispersion relation, lifetime, and pairing. In this work we analyze the signatures of Friedel oscillations in STM and x-ray scattering experiments, focusing on the concrete example of cuprate superconductors. We identify signatures of Friedel oscillations seeded by impurities and vortices, and explain experimental observations that have been previously attributed to a competing charge order.

  17. Spontaneous Oscillations of Elastic Contractile Materials with Turnover

    NASA Astrophysics Data System (ADS)

    Dierkes, Kai; Sumi, Angughali; Solon, Jérôme; Salbreux, Guillaume

    2014-10-01

    Single and collective cellular oscillations driven by the actomyosin cytoskeleton have been observed in numerous biological systems. Here, we propose that these oscillations can be accounted for by a generic oscillator model of a material turning over and contracting against an elastic element. As an example, we show that during dorsal closure of the Drosophila embryo, experimentally observed changes in actomyosin concentration and oscillatory cell shape changes can, indeed, be captured by the dynamic equations studied here. We also investigate the collective dynamics of an ensemble of such contractile elements and show that the relative contribution of viscous and friction losses yields different regimes of collective oscillations. Taking into account the diffusion of force-producing molecules between contractile elements, our theoretical framework predicts the appearance of traveling waves, resembling the propagation of actomyosin waves observed during morphogenesis.

  18. Scaling of oscillation frequencies in rotating stars

    NASA Astrophysics Data System (ADS)

    Castañeda, D.; Deupree, R. G.

    2016-06-01

    Properties of stars undergoing pulsation such as the well-known root-mean-density scaling relation can be useful when trying to match the observed properties of a particular star. It is often assumed that this relation is valid for p-mode frequencies in rotating stars. To examine the change in frequency with rotation and mass, we have studied oscillation frequencies of two-dimensional uniformly rotating zero-age main-sequence stellar models in the δ Scuti mass range. We identified axisymmetric p and g modes for non-rotating models and then traced them as the rotational velocity was increased. We considered a rotation sequence of ten models for four different masses, with the largest rotation rate being about 200 km s-1. The models were required to have the same surface shape between all masses for a given rotation rate. We find that scaling relationships exist among the oscillation frequencies of the same mode for different masses when the models have the same shape. For p modes, this scaling closely follows the period-root-mean-density relation found in spherical stars. The g modes also scale between models of the same shape, with the scaling reflecting the change in properties outside the convective core as the stellar mass increases. These scaling relationships can be particularly useful in finding specific stellar models to match the oscillation frequencies of individual stars. We also find that the large separation scales approximately with the root mean density as the rotation rate increases, although the individual mode frequencies do not.

  19. How to freeze drop oscillations with powders

    NASA Astrophysics Data System (ADS)

    Marston, Jeremy; Zhu, Ying; Vakarelski, Ivan; Thoroddsen, Sigurdur

    2012-11-01

    We present experiments that show when a water drop impacts onto a bed of fine, hydrophobic powder, the final form of the drop can be very different from the spherical form with which it impacts. For all drop impact speeds, the drop rebounds due to the hydrophobic nature of the powder. However, we observe that above a critical impact speed, the drop undergoes a permanent deformation to a highly non-spherical shape with a complete coverage of powder, thus creating a deformed liquid marble. This powder coating acts to freeze the drop oscillations during rebound.

  20. KamLAND's precision neutrino oscillation measurements

    NASA Astrophysics Data System (ADS)

    Decowski, M. P.

    2016-07-01

    The KamLAND experiment started operation in the Spring of 2002 and is operational to this day. The experiment observes signals from electron antineutrinos from distant nuclear reactors. The program, spanning more than a decade, allowed the determination of LMA-MSW as the solution to the solar neutrino transformation results (under the assumption of CPT invariance) and the measurement of various neutrino oscillation parameters. In particular, the solar mass-splitting Δ m212 was determined to high precision. Besides the study of neutrino oscillation, KamLAND started the investigation of geologically produced antineutrinos (geo-ν‾e). The collaboration also reported on a variety of other topics related to particle and astroparticle physics.

  1. Laser-Atomic Oscillator

    NASA Astrophysics Data System (ADS)

    Jau, Yuan-Yu; Happer, William

    2008-05-01

    We report a newly developed technique, laser-atomic oscillator, for simultaneously generating stable optical and electrical modulations with a very few components. It requires only a semiconductor laser, a vapor cell, and a few optical components. No photodetector and electronic feedback are needed. In this new system, the ground-state hyperfine coherence of alkali-metal atoms is spontaneously generated. The modulated laser light with a spectrum of a small optical comb is automatically produced, and the spacing between the comb peaks is photonically locked to the hyperfine frequency. The charge carriers in the semiconductor laser are also modulated at the hyperfine frequency. Laser-atomic oscillator is purely optical. Its simple structure allows the system to be very compact. We believe this new technique will bring some advantages in the applications of atomic chronometry, atomic magnetometry, and generation of multi-coherent light.

  2. Oscillations of complex networks

    NASA Astrophysics Data System (ADS)

    Wang, Xingang; Lai, Ying-Cheng; Lai, Choy Heng

    2006-12-01

    A complex network processing information or physical flows is usually characterized by a number of macroscopic quantities such as the diameter and the betweenness centrality. An issue of significant theoretical and practical interest is how such quantities respond to sudden changes caused by attacks or disturbances in recoverable networks, i.e., functions of the affected nodes are only temporarily disabled or partially limited. By introducing a model to address this issue, we find that, for a finite-capacity network, perturbations can cause the network to oscillate persistently in the sense that the characterizing quantities vary periodically or randomly with time. We provide a theoretical estimate of the critical capacity-parameter value for the onset of the network oscillation. The finding is expected to have broad implications as it suggests that complex networks may be structurally highly dynamic.

  3. Stable local oscillator module.

    SciTech Connect

    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.

  4. JFET reflection oscillator

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L. (Inventor)

    1985-01-01

    A high frequency oscillator circuit is provided using a low cost junction type field effect transistor (T sub 1) with a tuned circuit connected to its gate. The frequency of operation is determined by the tuned circuit and the capacitance reflected from the source to the gate. The transistor is matched to the frequency of operation so that this frequency falls within the roll-off portion of the transistor's transconductance verses frequency curve, preferably somewhat above the 3 db point in frequency. Phase shift necessary to sustain oscillation occurs due to the operation of the transistor in the roll-off portion of the curve and the addition of a phase shifting network (R sub 1, C sub 1) at the source.

  5. Phase chaos in coupled oscillators.

    PubMed

    Popovych, Oleksandr V; Maistrenko, Yuri L; Tass, Peter A

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems. PMID:16089804

  6. Phase chaos in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Popovych, Oleksandr V.; Maistrenko, Yuri L.; Tass, Peter A.

    2005-06-01

    A complex high-dimensional chaotic behavior, phase chaos, is found in the finite-dimensional Kuramoto model of coupled phase oscillators. This type of chaos is characterized by half of the spectrum of Lyapunov exponents being positive and the Lyapunov dimension equaling almost the total system dimension. Intriguingly, the strongest phase chaos occurs for intermediate-size ensembles. Phase chaos is a common property of networks of oscillators of very different natures, such as phase oscillators, limit-cycle oscillators, and chaotic oscillators, e.g., Rössler systems.

  7. Covariant deformed oscillator algebras

    NASA Technical Reports Server (NTRS)

    Quesne, Christiane

    1995-01-01

    The general form and associativity conditions of deformed oscillator algebras are reviewed. It is shown how the latter can be fulfilled in terms of a solution of the Yang-Baxter equation when this solution has three distinct eigenvalues and satisfies a Birman-Wenzl-Murakami condition. As an example, an SU(sub q)(n) x SU(sub q)(m)-covariant q-bosonic algebra is discussed in some detail.

  8. LSND neutrino oscillation results

    SciTech Connect

    White, D.H.; LSND Collaboration

    1997-11-01

    The LSND experiment at Los Alamos has conducted a search for {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations using {anti v}{sub {mu}} from {mu}{sup +} decay at rest. The {anti v}{sub e} are detected via the reaction {anti v}{sub e} p {yields} e{sup +}n, correlated with the 2.2 MeV {gamma} from n p {yields} d {gamma}. The use of tight cuts to identify e{sup +} events with correlated {gamma} rays yielded 22 events with e{sup +} energy between 36 and 60 MeV and only 4.6 {+-} 0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1 {times} 10{sup {minus}8}. A {chi}{sup 2} fit to the entire e{sup +} sample results in a total excess of 51.8{sub {minus}16.9}{sup +18.7} {+-} 8.0 events with e{sup +} energy between 20 and 60 MeV. If attributed to {anti v}{sub {mu}} {yields} {anti v}{sub e} oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of 0.31 {+-} 0.12 {+-} 0.05%.

  9. LSND neutrino oscillation results

    SciTech Connect

    Louis, W.C.; LSND Collaboration

    1996-10-01

    The LSND (Liquid Scintillator Neutrino Detector) experiment at Los Alamos has conducted a search for muon antineutrino {r_arrow} electron antineutrino oscillations using muon neutrinos from antimuon decay at rest. The electron antineutrinos are detected via the reaction electron antineutrino + proton {r_arrow} positron + neutron, correlated with the 2.2-MeV gamma from neutron + proton {r_arrow} deuteron + gamma. The use of tight cuts to identify positron events with correlated gamma rays yields 22 events with positron energy between 36 and 60 MeV and only 4.6 {+-} 0.6 background events. The probability that this excess is due entirely to a statistical fluctuation is 4.1 {times} 10{sup -8}. A chi-squared fit to the entire positron sample results in a total excess of 51.8 {sup +18.7}{sub -16.9} {+-} 8.0 events with positron energy between 20 and 60 MeV. If attributed to muon antineutrino {r_arrow} electron antineutrino oscillations, this corresponds to an oscillation probability (averaged over the experimental energy and spatial acceptance) of (0.31 {+-} 0.12 {+-} 0.05){percent}. 10 refs., 7 figs., 1 tab.

  10. Temperature sensitive oscillator

    NASA Technical Reports Server (NTRS)

    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.

  11. Biochemical Oscillations and Cellular Rhythms

    NASA Astrophysics Data System (ADS)

    Goldbeter, Albert; Berridge, Foreword by M. J.

    1997-04-01

    1. Introduction; Part I. Glycolytic Oscillations: 2. Oscillatory enzymes: simple periodic behaviour in an allosteric model for glycolytic oscillations; Part II. From Simple to Complex Oscillatory Behaviour; 3. Birhythmicity: coexistence between two stable rhythms; 4. From simple periodic behaviour to complex oscillations, including bursting and chaos; Part III. Oscillations Of Cyclic Amo In Dictyostelium Cells: 5. Models for the periodic synthesis and relay of camp signals in Dictyostelium discoideum amoebae; 6. Complex oscillations and chaos in the camp signalling system of Dictyostelium; 7. The onset of camp oscillations in Dictyostelium as a model for the ontogenesis of biological rhythms; Part IV. Pulsatile Signalling In Intercellular Communication: 8. Function of the rhythm of intercellular communication in Dictyostelium. Link with pulsatile hormone secretion; Part V. Calcium Oscillations: 9. Oscillations and waves of intracellular calcium; Part VI. The Mitotic Oscillator: 10. Modelling the mitotic oscillator driving the cell division cycle; Part VII. Circadian Rhythms: 11. Towards a model for circadian oscillations in the Drosophila period protein (PER); 12. Conclusions and perspectives; References.

  12. Oyster Creek fuel thermal margin during core thermal-hydraulic oscillations

    SciTech Connect

    Dougher, J.D.

    1990-01-01

    The Oyster Creek nuclear facility, a boiling water reactor (BWR)-2 plant type, has never experienced core thermal-hydraulic instability. Power oscillations, however, have been observed in other BWR cores both domestically and internationally. Two modes of oscillations have been observed, core wide and regional half-core. During core wide oscillations, the neutron flux in the core oscillates in the radial fundamental mode. During regional half-core oscillations, higher order harmonics in the radial plane result in out-of-phase oscillations with the neutron flux in one half of the core oscillating 180 deg out-of-phase with the neutron flux in the other half of the core. General Design Criteria 12 requires either prevention or detection and suppression of power oscillations which could result in violations of fuel design limits. Analyses performed by General Electric have demonstrated that for large-magnitude oscillations the potential exists for violation of the safety limit minimum critical power ratio (MCPR). However, for plants with a flow-biased neutron flux scram automatic mitigation of oscillations may be provided at an oscillation magnitude below that at which the safety limit is challenged. Plant-specific analysis for Oyster Creek demonstrates that the existing average power range monitor (APRM) system will sense and suppress power oscillations prior to violation of any safety limits.

  13. Nonlinear Oscillators in Space Physics

    NASA Technical Reports Server (NTRS)

    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.

  14. Surface tension and viscosity from damped free oscillations of viscous droplets

    NASA Technical Reports Server (NTRS)

    Suryanarayana, P. V. R.; Bayazitoglu, Yildiz

    1990-01-01

    Damped oscillations of a viscous droplet in vacuum or in an inert gas of negligible density are considered. The dependence of the complex decay factor on the properties of the liquid is investigated for the first time, and numerical results are compared with earlier studies for special cases. A new method is developed to determine both surface tension and viscosity from a single experiment in which the damping rate and frequency of oscillations are measured. The procedure to determine surface tension and viscosity from oscillating levitated liquids is outlined, and results presented for various modes of shape oscillations.

  15. Development of fluidic oscillators as flow control actuators

    NASA Astrophysics Data System (ADS)

    Gregory, James Winborn

    applying the paint to various flowfields. The polymer/ceramic formulation is used to record the 12-kHz oscillating shock wave and propagating acoustic waves generated by a Hartmann oscillator. Polymer/ceramic PSP is also used to measure the acoustic mode shapes in a rectangular resonance cavity driven by a speaker at 145 dB. These results compare favorably to the analytical solution for the same geometry.

  16. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Turner, Brian P.; Dolan, James T.; Kirkpatrick, Douglas A.; Leng, Yongzhang

    2000-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to match the driving frequency of the oscillator to a plurality of tuning states of the lamp.

  17. High frequency inductive lamp and power oscillator

    DOEpatents

    MacLennan, Donald A.; Dymond, Jr., Lauren E.; Gitsevich, Aleksandr; Grimm, William G.; Kipling, Kent; Kirkpatrick, Douglas A.; Ola, Samuel A.; Simpson, James E.; Trimble, William C.; Tsai, Peter; Turner, Brian P.

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and I or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency. Various control circuits may be employed to adjust the driving frequency of the oscillator.

  18. Direct measurement of clarinet air column oscillations

    NASA Astrophysics Data System (ADS)

    Jones, Jesse; Rogers, Chris; French, Chris

    2003-10-01

    The internal oscillation of a clarinet air column has been directly measured through the implementation of hot-wire anemometry. By taking a series of measurements down the centerline of the bore, velocity and pressure modal shapes of individual harmonics are separated, measured, and plotted. Finally, composite averaged power spectra of the internal oscillation are presented and compared to acoustic measurements acquired outside the clarinet. In many cases, the even harmonics of the internal oscillation dominate over the power found in the odd harmonics. This contradicts the classic model of the clarinet as a cylindrical pipe closed at one end and open at the other (where only odd harmonics are produced). Further, the data from the direct velocity measurements also contradict the externally acquired acoustic data, where odd harmonics generally dominate for the lowest 5-9 harmonics. Thus the clarinet, in theory and practice, is generally considered incapable of generating strong even harmonics. In this research, however, it is seen that dominate even harmonics are generated, but the energy for these frequencies is largely trapped inside the clarinet, whereas the energy associated with the odd harmonics is released to the ambient. [This research was conducted with the support of Selmer Musical Instruments.

  19. Nuclear Speckles

    PubMed Central

    Spector, David L.; Lamond, Angus I.

    2011-01-01

    Nuclear speckles, also known as interchromatin granule clusters, are nuclear domains enriched in pre-mRNA splicing factors, located in the interchromatin regions of the nucleoplasm of mammalian cells. When observed by immunofluorescence microscopy, they usually appear as 20–50 irregularly shaped structures that vary in size. Speckles are dynamic structures, and their constituents can exchange continuously with the nucleoplasm and other nuclear locations, including active transcription sites. Studies on the composition, structure, and dynamics of speckles have provided an important paradigm for understanding the functional organization of the nucleus and the dynamics of the gene expression machinery. PMID:20926517

  20. Physics of self-sustained oscillations in the positive glow corona

    SciTech Connect

    Cho, Sung Nae

    2012-07-15

    The physics of self-sustained oscillations in the phenomenon of positive glow corona is presented. The dynamics of charged-particle oscillation under static electric field has been briefly outlined; and, the resulting self-sustained current oscillations in the electrodes have been compared with the measurements from the positive glow corona experiments. The profile of self-sustained electrode current oscillations predicted by the presented theory qualitatively agrees with the experimental measurements. For instance, the experimentally observed saw-tooth shaped electrode current pulses are reproduced by the presented theory. Further, the theory correctly predicts the pulses of radiation accompanying the abrupt rises in the saw-tooth shaped current oscillations, as verified from the various glow corona experiments.

  1. Burst Oscillations: Watching Neutron Stars Spin

    NASA Technical Reports Server (NTRS)

    Strohmayer, Tod

    2010-01-01

    It is now almost 15 years since the first detection of rotationally modulated emission from X-ray bursting neutron stars, "burst oscillations," This phenomenon enables us to see neutron stars spin, as the X-ray burst flux asymmetrically lights up the surface. It has enabled a new way to probe the neutron star spin frequency distribution, as well as to elucidate the multidimensional nature of nuclear burning on neutron stars. I will review our current observational understanding of the phenomenon, with an eye toward highlighting some of the interesting remaining puzzles, of which there is no shortage.

  2. Directions for nuclear research in the transplutonium elements

    SciTech Connect

    Wilhelmy, J.B.; Chasman, R.R.; Friedman, A.M.; Ahmad, I.

    1983-01-01

    The study of the heavy nuclides has played a vital role in our understanding of the alpha decay process, nuclear fission, nuclear binding energies and the limits of nuclear stability. This study has led to the understanding of novel shape degrees of freedom, such as the very large quadrupole deformations associated with the fission isomer process, and the very recently discovered octupole deformation. The existence of these unique phenomena in the heavy element region is not accidental. Fission isomerism is due to the delicate balance between nuclear forces holding the nucleus together and Coulomb forces causing nuclear fission. Octupole deformation arises from the increasing strength of matrix elements with increasing oscillator shell. Both illustrate the unique features of the heavy element region. Fission studies have given us information about large collective aspects in nuclei and the importance that nuclear structural effects can play in altering these macro properties. A new class of atomic studies has become possible with the availability of heavy elements. With these isotopes, we are now able to produce electric fields of such magnitude that it becomes possible to spontaneously create positron-electron pairs in the vacuum. We have organized this presentation into three major sections: nuclear structure, fission studies and atomic studies of supercritical systems. In each we will try to emphasize the new directions which can benefit from the continued availability of isotopes supplied by the Trans-plutonium Production Program. 117 references. (WHK)

  3. Shape-Shifting Plastic

    SciTech Connect

    2015-05-20

    A new plastic developed by ORNL and Washington State University transforms from its original shape through a series of temporary shapes and returns to its initial form. The shape-shifting process is controlled through changes in temperature

  4. Synchronous Discrete Harmonic Oscillator

    SciTech Connect

    Antippa, Adel F.; Dubois, Daniel M.

    2008-10-17

    We introduce the synchronous discrete harmonic oscillator, and present an analytical, numerical and graphical study of its characteristics. The oscillator is synchronous when the time T for one revolution covering an angle of 2{pi} in phase space, is an integral multiple N of the discrete time step {delta}t. It is fully synchronous when N is even. It is pseudo-synchronous when T/{delta}t is rational. In the energy conserving hyperincursive representation, the phase space trajectories are perfectly stable at all time scales, and in both synchronous and pseudo-synchronous modes they cycle through a finite number of phase space points. Consequently, both the synchronous and the pseudo-synchronous hyperincursive modes of time-discretization provide a physically realistic and mathematically coherent, procedure for dynamic, background independent, discretization of spacetime. The procedure is applicable to any stable periodic dynamical system, and provokes an intrinsic correlation between space and time, whereby space-discretization is a direct consequence of background-independent time-discretization. Hence, synchronous discretization moves the formalism of classical mechanics towards that of special relativity. The frequency of the hyperincursive discrete harmonic oscillator is ''blue shifted'' relative to its continuum counterpart. The frequency shift has the precise value needed to make the speed of the system point in phase space independent of the discretizing time interval {delta}t. That is the speed of the system point is the same on the polygonal (in the discrete case) and the circular (in the continuum case) phase space trajectories.

  5. THz Local Oscillator Sources

    NASA Astrophysics Data System (ADS)

    Mehdi, Imran; Schlecht, Erich; Chattopadhyay, Goutam; Siegel, Peter H.

    Most operational Submillimeter-wave radio telescopes, both space borne and ground based, employ local oscillator sources based on Gunn diodes followed by whisker contacted Schottky multipliers. Enough progress, however, has been made on a number of fronts to conclude that next generation of radio telescopes that become operational in the new Millennium will have a different local oscillator (LO) generation architecture. MMIC power amplifiers with impressive gain in the Ka- to-W band have enabled the use of microwave synthesizers which can then be actively multiplied to provide a frequency agile power source beyond 100 GHz. This medium power millimeter source can then be amplified to enable efficient pumping of follow-on balanced multiplier stages. Input power to the multipliers can be further enhanced by power combining to achieve close to half a Watt at W-band. An 800 GHz three-stage multiplier chain, implemented this way has demonstrated a peak output power of 1 mW. A second advance in LO generation lies in the Schottky diode varactor technology. Planar Schottky diode multipliers have now been demonstrated up to 1500 GHz and it can be assumed that most of the future multiplier chains will be based on these robust devices rather than the whisker contacted diode of the past. The ability to produce planar GaAs diode chips deep into the THz range, with submicron dimensions, has opened up a wide range of circuit design space which can be taken advantage of to improve efficiency, bandwidth, and power handling capability of the multipliers. A third breakthrough has been the demonstration of photonic based LO sources utilizing GaAs photomixers. These sources, though not yet implemented in robust space borne missions, offer a number of advantages over their electronic counterparts, including extremely broad tuning, fiber coupled components, and solid-state implementation. Another development, which holds some promise, is the use of micro-machining technology to implement

  6. CORE SATURATION BLOCKING OSCILLATOR

    DOEpatents

    Spinrad, R.J.

    1961-10-17

    A blocking oscillator which relies on core saturation regulation to control the output pulse width is described. In this arrangement an external magnetic loop is provided in which a saturable portion forms the core of a feedback transformer used with the thermionic or semi-conductor active element. A first stationary magnetic loop establishes a level of flux through the saturation portion of the loop. A second adjustable magnet moves the flux level to select a saturation point giving the desired output pulse width. (AEC)

  7. Second harmonic FEL oscillation

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Benson, S. V.; Biallas, G.; Freund, H. P.; Gubeli, J.; Jordan, K.; Myers, S.; Shinn, M. D.

    2002-05-01

    We have produced and measured for the first time second harmonic oscillation in the infrared region by the high-average-power Jefferson Lab Infrared Free Electron Laser. The finite geometry and beam emittance allows sufficient gain for lasing to occur. We were able to lase at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM 01 mode. We present results of initial source performance measurements and comparisons with theory and simulation.

  8. Second Harmonic FEL Oscillation

    NASA Astrophysics Data System (ADS)

    Neil, George R.; Benson, S. V.; Biallas, G.; Gubeli, J.; Jordan, K.; Myers, S.; Shinn, M. D.

    2001-08-01

    We have produced and measured for the first time second harmonic oscillation in the infrared region by a free electron laser. Although such lasing is ideally forbidden, since the gain of a plane wave is zero on axis for an electron beam perfectly aligned with a wiggler, a transverse mode antisymmetry allows sufficient gain in this experiment for lasing to occur. We lased at pulse rates up to 74.85 MHz and could produce over 4.5 W average and 40 kW peak of IR power in a 40 nm FWHM bandwidth at 2925 nm. In agreement with predictions, the source preferentially lased in a TEM01 mode.

  9. Multipole moments of stellar oscillation modes

    NASA Technical Reports Server (NTRS)

    Reisenegger, Andreas

    1994-01-01

    The oscillating mass 2(exp l)-pole moment, M(sub nl), of a star in a given (normalized) oscillation mode determines the energy that can be absorbed by the mode in a tidal interaction and the power radiated by the mode in gravitational waves, both of which are proportional to (absolute value of M(sub nl))(exp 2). The coefficients in the expansion of the vector fields del(r(exp l)Y(sub lm)(theta, phi)) in terms of the displacement fields of modes of given l and m are proportional to M(sub nl). This expansion leads to a sum rule sum over n(absolute value of M(sub nl))(exp 2) = constant. For stars of weak to moderate central condensation (such as neutron stars), the f-mode is well approximated by the vector field being expanded, and therefore it takes the lion's share of the sum. Thus the multipole moments of all other modes must be small. In there numerical evaluation, it is necessary to know the shape of the eigenfunctions quite precisly, since a small f-mode contamination can significantly increase the obtained values. This contamination occurs in some `hybrid' numerical computations of neutron star oscillations with relativistic equilibrium stars and Newtonian dynamics (e.g., McDermott et al. 1988). In this case, it is due to a slight inconsistency in the models and leads to a large overestimate of the power radiated in gravitational waves by modes other than the f-mode, although their oscillation periods are nearly unaffected.

  10. Triple shape memory effect of star-shaped polyurethane.

    PubMed

    Yang, Xifeng; Wang, Lin; Wang, Wenxi; Chen, Hongmei; Yang, Guang; Zhou, Shaobing

    2014-05-14

    In this study, we synthesized one type of star-shaped polyurethane (SPU) with star-shaped poly(ε-caprolactone) (SPCL) containing different arm numbers as soft segment and 4,4'-diphenyl methane diisocyanate (MDI) as well as chain extender 1,4-butylene glycol (BDO) as hard segment. Proton nuclear magnetic resonance (1H-NMR) confirmed the chemical structure of the material. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) results indicated that both the melting temperature (Tm) and transition temperature (Ttrans) of SPU decreased with the hard segment composition increase. X-ray diffraction (XRD) results demonstrated that the increase of the crystallinity of SPU following the raised arm numbers endowed a high shape fixity of six-arm star-shaped polyurethane (6S-PU) and a wide melting temperature range, which resulted in an excellent triple-shape memory effect of 6S-PU. The in vitro cytotoxicity assay evaluated with osteoblasts through Alamar blue assay demonstrates that this copolymer possessed good cytocompatibility. This material can be potentially used as a new smart material in the field of biomaterials. PMID:24617646

  11. Tooth - abnormal shape

    MedlinePlus

    Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... The appearance of normal teeth varies, especially the molars. ... conditions. Specific diseases can affect tooth shape, tooth ...

  12. Tooth - abnormal shape

    MedlinePlus

    Hutchinson incisors; Abnormal tooth shape; Peg teeth; Mulberry teeth; Conical teeth ... from many different conditions. Specific diseases can affect tooth shape, tooth color, time of appearance, or absence ...

  13. Brain Oscillations, Hypnosis, and Hypnotizability

    PubMed Central

    Jensen, Mark P.; Adachi, Tomonori; Hakimian, Shahin

    2014-01-01

    In this article, we summarize the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, and are usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. Here we propose that it is this role that may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis; specifically that theta oscillations may facilitate, and that changes in gamma activity observed with hypnosis may underlie, some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis, and for enhancing response to hypnotic treatments. PMID:25792761

  14. A single ion anharmonic mechanical oscillator with nonlinear dissipation

    NASA Astrophysics Data System (ADS)

    Akerman, Nitzan; Kotler, Shlomi; Glickman, Yinnon; Keselman, Anna; Dallal, Yehonatan; Ozeri, Roee

    2010-03-01

    A driven, damped, nearly harmonic oscillator with a small cubic term in the force, is known as the Duffing oscillator. The Duffing oscillator shows various interesting features of non-linear response such as bistability and hysteresis. Several features of the Duffing instability have been recently measured using superconducting qubits and nano-mechanical resonators. Linear Paul traps can be well approximated as harmonic but have a small an-harmonicity due to their deviation from an ideal quadruple geometry. We study the steady state motion of a single trapped Sr^+ ion, subject to a near-resonance drive and dissipation in a linear Paul trap with a small anharmonicity. The driving force is applied by an oscillating voltage on the trap end-caps. Dissipation is the result of laser Doppler cooling. We measure both the amplitude and phase of the driven oscillations and find a good agreement with the Duffing oscillator model. When the cooling laser is close to resonance the standard Duffing model has to be extended to account for non-linearity in the dissipative force. Both the linear and the nonlinear terms of the dissipative force for various cooling laser detunings are determined by the line-shape of the - cooling transition and the cooling laser intensity and can therefore be conveniently controlled.

  15. Double Chooz and the search for short range anti-neutrino oscillations

    NASA Astrophysics Data System (ADS)

    Hartmann, Francis X.

    2009-06-01

    The Double Chooz Experiment seeks to search for short range antineutrino oscillations from the nuclear reactors at the Chooz Nuclear Power Station operated by Electricite de France in Northeastern France. The measurements are of interest to constraining the value for θ13 in current neutrino oscillation models. New scintillator types based on beta-diketone and pH stabilized carboxylic acid chemistry are described. New results from the study of these scintillators in the context of the detector design are reported.

  16. Stable And Oscillating Acoustic Levitation

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin B.; Garrett, Steven L.

    1988-01-01

    Sample stability or instability determined by levitating frequency. Degree of oscillation of acoustically levitated object along axis of levitation chamber controlled by varying frequency of acoustic driver for axis above or below frequency of corresponding chamber resonance. Stabilization/oscillation technique applied in normal Earth gravity, or in absence of gravity to bring object quickly to rest at nominal levitation position or make object oscillate in desired range about that position.

  17. Digital image processing of sectorial oscillations for acoustically levitated drops and surface tension measurement

    NASA Astrophysics Data System (ADS)

    Shen, Changle; Xie, Wenjun; Wei, Bingbo

    2010-12-01

    A type of non-axisymmetric oscillations of acoustically levitated drops is excited by modulating the ultrasound field at proper frequencies. These oscillations are recorded by a high speed camera and analyzed with a digital image processing method. They are demonstrated to be the third mode sectorial oscillations, and their frequencies are found to decrease with the increase of equatorial radius of the drops, which can be described by a modified Rayleigh equation. These oscillations decay exponentially after the cessation of ultrasound field modulation. The decaying rates agree reasonably with Lamb's prediction. The rotating rate of the drops accompanying the shape oscillations is found to be less than 1.5 rounds per second. The surface tension of aqueous ethanol has been measured according to the modified Rayleigh equation. The results agree well with previous reports, which demonstrates the possible application of this kind of sectorial oscillations in noncontact measurement of liquid surface tension.

  18. Policy oscillation is overshooting.

    PubMed

    Wagner, Paul

    2014-04-01

    A majority of approximate dynamic programming approaches to the reinforcement learning problem can be categorized into greedy value function methods and value-based policy gradient methods. The former approach, although fast, is well known to be susceptible to the policy oscillation phenomenon. We take a fresh view to this phenomenon by casting, within the context of non-optimistic policy iteration, a considerable subset of the former approach as a limiting special case of the latter. We explain the phenomenon in terms of this view and illustrate the underlying mechanism with artificial examples. We also use it to derive the constrained natural actor-critic algorithm that can interpolate between the aforementioned approaches. In addition, it has been suggested in the literature that the oscillation phenomenon might be subtly connected to the grossly suboptimal performance in the Tetris benchmark problem of all attempted approximate dynamic programming methods. Based on empirical findings, we offer a hypothesis that might explain the inferior performance levels and the associated policy degradation phenomenon, and which would partially support the suggested connection. Finally, we report scores in the Tetris problem that improve on existing dynamic programming based results by an order of magnitude. PMID:24491826

  19. Extinction of oscillating populations.

    PubMed

    Smith, Naftali R; Meerson, Baruch

    2016-03-01

    Established populations often exhibit oscillations in their sizes that, in the deterministic theory, correspond to a limit cycle in the space of population sizes. If a population is isolated, the intrinsic stochasticity of elemental processes can ultimately bring it to extinction. Here we study extinction of oscillating populations in a stochastic version of the Rosenzweig-MacArthur predator-prey model. To this end we develop a WKB (Wentzel, Kramers and Brillouin) approximation to the master equation, employing the characteristic population size as the large parameter. Similar WKB theories have been developed previously in the context of population extinction from an attracting multipopulation fixed point. We evaluate the extinction rates and find the most probable paths to extinction from the limit cycle by applying Floquet theory to the dynamics of an effective four-dimensional WKB Hamiltonian. We show that the entropic barriers to extinction change in a nonanalytic way as the system passes through the Hopf bifurcation. We also study the subleading pre-exponential factors of the WKB approximation. PMID:27078294

  20. Extinction of oscillating populations

    NASA Astrophysics Data System (ADS)

    Smith, Naftali R.; Meerson, Baruch

    2016-03-01

    Established populations often exhibit oscillations in their sizes that, in the deterministic theory, correspond to a limit cycle in the space of population sizes. If a population is isolated, the intrinsic stochasticity of elemental processes can ultimately bring it to extinction. Here we study extinction of oscillating populations in a stochastic version of the Rosenzweig-MacArthur predator-prey model. To this end we develop a WKB (Wentzel, Kramers and Brillouin) approximation to the master equation, employing the characteristic population size as the large parameter. Similar WKB theories have been developed previously in the context of population extinction from an attracting multipopulation fixed point. We evaluate the extinction rates and find the most probable paths to extinction from the limit cycle by applying Floquet theory to the dynamics of an effective four-dimensional WKB Hamiltonian. We show that the entropic barriers to extinction change in a nonanalytic way as the system passes through the Hopf bifurcation. We also study the subleading pre-exponential factors of the WKB approximation.

  1. Neutrino Oscillations:. Hierarchy Question

    NASA Astrophysics Data System (ADS)

    Ernst, D. J.; Cogswell, B. K.; Burroughs, H. R.; Escamilla-Roa, J.; Latimer, D. L.

    2014-09-01

    The only experimentally observed phenomenon that lies outside the standard model of the electroweak interaction is neutrino oscillations. A way to try to unify the extensive neutrino oscillation data is to add a phenomenological mass term to the Lagrangian that is not diagonal in the flavor basis. The goal is then to understand the world's data in terms of the parameters of the mixing matrix and the differences between the squares of the masses of the neutrinos. An outstanding question is what is the correct ordering of the masses, the hierarchy question. We point out a broken symmetry relevant to this question, the symmetry of the simultaneous interchange of hierarchy and the sign of θ13. We first present the results of an analysis of data that well determine the phenomenological parameters but are not sensitive to the hierarchy. We find θ13 = 0.152±0.014, θ 23 = 0.25{ - 0.05}{ + 0.03} π and Δ32 = 2.45±0.14×10-3 eV2, results consistent with others. We then include data that are sensitive to the hierarchy and the sign of θ13. We find, unlike others, four isolated minimum in the χ2-space as predicted by the symmetry. Now that Daya Bay and RENO have determined θ13 to be surprisingly large, the Super-K atmospheric data produce meaningful symmetry breaking such that the inverse hierarchy is preferred at the 97.2 % level.

  2. Neutrino oscillations refitted

    NASA Astrophysics Data System (ADS)

    Forero, D. V.; Tórtola, M.; Valle, J. W. F.

    2014-11-01

    Here, we update our previous global fit of neutrino oscillations by including the recent results that have appeared since the Neutrino 2012 conference. These include the measurements of reactor antineutrino disappearance reported by Daya Bay and RENO, together with latest T2K and MINOS data including both disappearance and appearance channels. We also include the revised results from the third solar phase of Super-Kamiokande, SK-III, as well as new solar results from the fourth phase of Super-Kamiokande, SK-IV. We find that the preferred global determination of the atmospheric angle θ23 is consistent with maximal mixing. We also determine the impact of the new data upon all the other neutrino oscillation parameters with an emphasis on the increasing sensitivity to the C P phase, thanks to the interplay between accelerator and reactor data. In the Appendix, we present the updated results obtained after the inclusion of new reactor data presented at the Neutrino 2014 conference. We discuss their impact on the global neutrino analysis.

  3. Chemotaxis and Actin Oscillations

    NASA Astrophysics Data System (ADS)

    Bodenschatz, Eberhard; Hsu, Hsin-Fang; Negrete, Jose; Beta, Carsten; Pumir, Alain; Gholami, Azam; Tarantola, Marco; Westendorf, Christian; Zykov, Vladimir

    Recently, self-oscillations of the cytoskeletal actin have been observed in Dictyostelium, a model system for studying chemotaxis. Here we report experimental results on the self-oscillation mechanism and the role of regulatory proteins and myosin II. We stimulate cells rapidly and periodically by using photo un-caging of the chemoattractant in a micro-fluidic device and measured the cellular responses. We found that the response amplitude grows with stimulation strength only in a very narrow region of stimulation, after which the response amplitude reaches a plateau. Moreover, the frequency-response is not constant but rather varies with the strength of external stimuli. To understand the underlying mechanism, we analyzed the polymerization and de-polymerization time in the single cell level. Despite of the large cell-to-cell variability, we found that the polymerization time is independent of external stimuli and the de-polymerization time is prolonged as the stimulation strength increases. Our conclusions will be summarized and the role of noise in the signaling network will be discussed. German Science Foundation CRC 937.

  4. Socially synchronized circadian oscillators

    PubMed Central

    Bloch, Guy; Herzog, Erik D.; Levine, Joel D.; Schwartz, William J.

    2013-01-01

    Daily rhythms of physiology and behaviour are governed by an endogenous timekeeping mechanism (a circadian ‘clock’). The alternation of environmental light and darkness synchronizes (entrains) these rhythms to the natural day–night cycle, and underlying mechanisms have been investigated using singly housed animals in the laboratory. But, most species ordinarily would not live out their lives in such seclusion; in their natural habitats, they interact with other individuals, and some live in colonies with highly developed social structures requiring temporal synchronization. Social cues may thus be critical to the adaptive function of the circadian system, but elucidating their role and the responsible mechanisms has proven elusive. Here, we highlight three model systems that are now being applied to understanding the biology of socially synchronized circadian oscillators: the fruitfly, with its powerful array of molecular genetic tools; the honeybee, with its complex natural society and clear division of labour; and, at a different level of biological organization, the rodent suprachiasmatic nucleus, site of the brain's circadian clock, with its network of mutually coupled single-cell oscillators. Analyses at the ‘group’ level of circadian organization will likely generate a more complex, but ultimately more comprehensive, view of clocks and rhythms and their contribution to fitness in nature. PMID:23825203

  5. Theories of white dwarf oscillations

    NASA Technical Reports Server (NTRS)

    Vanhorn, H. M.

    1980-01-01

    The current status of theoretical understanding of the oscillations observed in the ZZ Ceti stars and cataclysmic variables is briefly reviewed. Nonradial g-mode oscillations appear to provide a satisfactory explanation for the low amplitude variables such as R548, with periods in the range of approximately 200 to 300 seconds, but for the longer period (800 to 1000 seconds) oscillators, the situation is still unclear. Rotation may play an important role in this problem, and the effects of both slow and fast rotation upon the mode structure are discussed. In the cataclysmic variables, both accretion and thermonuclear burning may act to excite oscillations of the white dwarf.

  6. Modelling Ultradian Oscillations and Segmentation

    NASA Astrophysics Data System (ADS)

    Jensen, Mogens

    2008-03-01

    We model ultradian oscillations in four different eucaryotic systems: Hes1, p53-mdm2, NF-kB and Wnt-Notch. In each of the systems we identify the feed-back loops for the genetic regulations. Oscillations are possible when time delays are present, either by directly introducing a delay, by many steps in the loops or by saturated degradation. The oscillations are important for apoptosis and control of inflammation. The Wnt-Notch system is essential in embryo segmentation and we introduce a model in which the Wnt oscillates by itself but drives the Notch cycle out of phase with the Wnt cycle, in good agreement with experimental observations.

  7. Quartz-crystal-oscillator hygrometer

    NASA Technical Reports Server (NTRS)

    Kruger, R.

    1977-01-01

    Measuring device, which eliminates complex and expensive optical components by electronically sensing dewpoint of water vapor in gas, employs piezoelectric crystal oscillator, supportive circuitry, temperature regulators, and readout.

  8. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  9. Heat exchanger with oscillating flow

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  10. Symmetries of coupled harmonic oscillators

    NASA Technical Reports Server (NTRS)

    Han, D.; Kim, Y. S.

    1993-01-01

    It is shown that the system of two coupled harmonic oscillators possesses many interesting symmetries. It is noted that the symmetry of a single oscillator is that of the three-parameter group Sp(2). Thus two uncoupled oscillator exhibits a direct product of two Sp(2) groups, with six parameters. The coupling can be achieved through a rotation in the two-dimensional space of two oscillator coordinates. The closure of the commutation relations for the generators leads to the ten-parameter group Sp(4) which is locally isomorphic to the deSitter group O(3,2).

  11. Neutrinos in Nuclear Physics

    SciTech Connect

    McKeown, Bob

    2015-06-01

    Since the discovery of nuclear beta decay, nuclear physicists have studied the weak interaction and the nature of neutrinos. Many recent and current experiments have been focused on the elucidation of neutrino oscillations and neutrino mass. The quest for the absolute value of neutrino mass continues with higher precision studies of the tritium beta decay spectrum near the endpoint. Neutrino oscillations are studied through measurements of reactor neutrinos as a function of baseline and energy. And experiments searching for neutrinoless double beta decay seek to discover violation of lepton number and establish the Majorana nature of neutrino masses.

  12. Fluctuations in the shape transitions of hot nuclei

    NASA Astrophysics Data System (ADS)

    Pacheco, J. M.; Yannouleas, C.; Broglia, R. A.

    1988-07-01

    The effect of quantal and thermal quadrupole shape fluctuations in the giant dipole response function of hot nuclei at high spin is studied within the Landau theory of phase transitions. The effects are found to be important in the relation of the nuclear shape to the experimental findings and in the identification of shape phase transitions.

  13. Wedding ring shaped excitation coil

    DOEpatents

    MacLennan, Donald A.; Tsai, Peter

    2001-01-01

    A high frequency inductively coupled electrodeless lamp includes an excitation coil with an effective electrical length which is less than one half wavelength of a driving frequency applied thereto, preferably much less. The driving frequency may be greater than 100 MHz and is preferably as high as 915 MHz. Preferably, the excitation coil is configured as a non-helical, semi-cylindrical conductive surface having less than one turn, in the general shape of a wedding ring. At high frequencies, the current in the coil forms two loops which are spaced apart and parallel to each other. Configured appropriately, the coil approximates a Helmholtz configuration. The lamp preferably utilizes an bulb encased in a reflective ceramic cup with a pre-formed aperture defined therethrough. The ceramic cup may include structural features to aid in alignment and/or a flanged face to aid in thermal management. The lamp head is preferably an integrated lamp head comprising a metal matrix composite surrounding an insulating ceramic with the excitation integrally formed on the ceramic. A novel solid-state oscillator preferably provides RF power to the lamp. The oscillator is a single active element device capable of providing over 70 watts of power at over 70% efficiency.

  14. Regulating Cortical Oscillations in an Inhibition-Stabilized Network.

    PubMed

    Jadi, Monika P; Sejnowski, Terrence J

    2014-04-21

    Understanding the anatomical and functional architecture of the brain is essential for designing neurally inspired intelligent systems. Theoretical and empirical studies suggest a role for narrowband oscillations in shaping the functional architecture of the brain through their role in coding and communication of information. Such oscillations are ubiquitous signals in the electrical activity recorded from the brain. In the cortex, oscillations detected in the gamma range (30-80 Hz) are modulated by behavioral states and sensory features in complex ways. How is this regulation achieved? Although several underlying principles for the genesis of these oscillations have been proposed, a unifying account for their regulation has remained elusive. In a network of excitatory and inhibitory neurons operating in an inhibition-stabilized regime, we show that strongly superlinear responses of inhibitory neurons facilitate bidirectional regulation of oscillation frequency and power. In such a network, the balance of drives to the excitatory and inhibitory populations determines how the power and frequency of oscillations are modulated. The model accounts for the puzzling increase in their frequency with the salience of visual stimuli, and a decrease with their size. Oscillations in our model grow stronger as the mean firing level is reduced, accounting for the size dependence of visually evoked gamma rhythms, and suggesting a role for oscillations in improving the signal-to-noise ratio (SNR) of signals in the brain. Empirically testing such predictions is still challenging, and implementing the proposed coding and communication strategies in neuromorphic systems could assist in our understanding of the biological system. PMID:24966414

  15. Solar oscillation frequency and solar neutrino predictions

    SciTech Connect

    Cox, A.N.

    1990-07-05

    The light and velocity variations of the Sun and solar-like stars are unique among intrinsic variable stars. Unlike all other standard classes, such as Cepheids, B stars, and white dwarfs, the pulsation driving is caused by coupling with the acoustic noise in the upper convection zone. Each global pulsation mode is just another degree of freedom for the turbulent convection, and energy is shared equally between these g{sup {minus}}-modes and the solar oscillation modes. This driving and damping, together with the normal stellar pulsation mechanisms produce extremely low amplitude solar oscillations. Actually, the surface layer radiative damping is strong, and the varying oscillation mode amplitudes manifest the stochastic convection driving and the steady damping. Thus stability calculations for solar-like pulsations are difficult and mostly inconclusive, but calculations of pulsation periods are as straightforward as for all the other classes of intrinsic variable stars. The issue that is important for the Sun is its internal structure, because the mass, radius, and luminosity are extremely well known. Conventionally, we need the pulsation constants for each of millions of modes. Unknown parameters for constructing solar models are the composition and its material pressure, energy, and opacity, as well as the convection mixing length. We treat the nuclear energy and neutrino production formulas as sufficiently well known. The presence of weakly interacting massive particles (WIMPs) orbiting the solar center affects the predicted oscillation frequencies so that they do not agree with observations as well as those for models without WIMPs. 34 refs., 4 figs.

  16. Shape memory polymers

    DOEpatents

    Wilson, Thomas S.; Bearinger, Jane P.

    2015-06-09

    New shape memory polymer compositions, methods for synthesizing new shape memory polymers, and apparatus comprising an actuator and a shape memory polymer wherein the shape memory polymer comprises at least a portion of the actuator. A shape memory polymer comprising a polymer composition which physically forms a network structure wherein the polymer composition has shape-memory behavior and can be formed into a permanent primary shape, re-formed into a stable secondary shape, and controllably actuated to recover the permanent primary shape. Polymers have optimal aliphatic network structures due to minimization of dangling chains by using monomers that are symmetrical and that have matching amine and hydroxyl groups providing polymers and polymer foams with clarity, tight (narrow temperature range) single transitions, and high shape recovery and recovery force that are especially useful for implanting in the human body.

  17. Stable local oscillator microcircuit.

    SciTech Connect

    Brocato, Robert Wesley

    2006-10-01

    This report gives a description of the development of a Stable Local Oscillator (StaLO) 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. The StaLO uses a comb generator followed by surface acoustic wave (SAW) filters. The comb generator creates a set of harmonic components of the 100MHz input signal. The SAW filters are narrow bandpass filters that are used to select the desired component and reject all others. The resulting circuit has very low sideband power levels and low phase noise (both less than -40dBc) that is limited primarily by the phase noise level of the input signal.

  18. Multifrequency optoelectronic oscillator

    NASA Astrophysics Data System (ADS)

    Jiang, Yang; Liang, Jianhui; Bai, Guangfu; Hu, Lin; Cai, Shaohong; Li, Hongxia; Shan, Yuanyuan; Ma, Chuang

    2014-11-01

    We propose a simple and cost-effective multifrequency optoelectronic oscillator (OEO) which is able to simultaneously generate two or more independent microwave signals by adding parallel filtering branches in the feedback loop. In the experimental demonstration, two signals with frequencies of 20 and 9 GHz are successfully generated. Compared with a conventional OEO, the generated signals have no additional noise and do not interfere with each other. The side-mode suppression by the optical dual-loop configuration is effective for both channels. The measured side-mode suppression ratios are larger than 65 dB, and the phase noises at a 10-kHz frequency offset are -108 and -113 dBc/Hz for 20 and 9-GHz signals, respectively.

  19. Galilean covariant harmonic oscillator

    NASA Technical Reports Server (NTRS)

    Horzela, Andrzej; Kapuscik, Edward

    1993-01-01

    A Galilean covariant approach to classical mechanics of a single particle is described. Within the proposed formalism, all non-covariant force laws defining acting forces which become to be defined covariantly by some differential equations are rejected. Such an approach leads out of the standard classical mechanics and gives an example of non-Newtonian mechanics. It is shown that the exactly solvable linear system of differential equations defining forces contains the Galilean covariant description of harmonic oscillator as its particular case. Additionally, it is demonstrated that in Galilean covariant classical mechanics the validity of the second Newton law of dynamics implies the Hooke law and vice versa. It is shown that the kinetic and total energies transform differently with respect to the Galilean transformations.

  20. Nonlinear effects on the natural modes of oscillation of a finite length inviscid fluid column, supplement 2

    NASA Technical Reports Server (NTRS)

    Lyell, M. J.; Zhang, L.

    1994-01-01

    The aspects of nonlinear behavior of a finite length liquid column is investigated with an emphasis on bridge dynamics. The primary objectives are to determine the nonlinear corrections to the interface shape of a naturally oscillating finite length liquid column and to determine the nonlinear corrections to the oscillation frequencies for various modes of oscillation. Application of the Lindstedt-Poincare expansion in conjunction with the domain perturbation techniques results in an hierarchical system of equations.

  1. A New Physical Model for Pulsars as Gravitational Shielding and Oscillating Neutron Stars

    NASA Astrophysics Data System (ADS)

    Zhang, Tianxi

    2014-06-01

    Pulsars are fast rotating neutron stars that synchronously emit periodic Dirac delta shape pulses of radio-frequency radiation and Lorentzian shape oscillations of X-rays. The acceleration of particles near the magnetic poles, which derivate from the rotating axis produces coherent beams of radio emissions that are viewed as pulses of radiation whenever the magnetic poles sweep the viewers. However, the conventional lighthouse model of pulsars is only conceptual. The physical mechanism through which particles are accelerated to produce coherent beams of radio emissions is still poorly understood. The process for periodically oscillating X-rays to emit from hot spots at the inner edge of accretion disks of pulsars is also remained as an unsolved mystery. Recently, a new physical model of pulsars is proposed by the author to quantitatively interpret the emission characteristics of pulsars, in accordance with his well-developed five-dimensional fully covariant Kaluza-Klein gravitational shielding theory and the physics of thermal and accelerating charged particle radiation. The results indicate that with the significant gravitational shielding by scalar field a neutron star nonlinearly oscillates and produces synchronous periodically Dirac delta shape pulse-like radio-frequency radiation (emitted by the oscillating or accelerating charged particles) as well as periodically Lorentzian shape oscillating X-rays (as the thermal radiation of neutron stars that temperature varies due to the oscillation). This physical model of pulsars as gravitational shielding and oscillating neutron stars broadens our understanding of neutron stars and develops an innovative mechanism to disclose the mystery of pulsars. In this presentation, I will show the results obtained from the quantitative studies of this new physical model of pulsars for the oscillations of neutron stars and the powers of radio pulse-like emissions and oscillating X-rays.

  2. Synchronized Rhythmic Oscillation in a Noisy Neural Network

    NASA Astrophysics Data System (ADS)

    Yu, Yuguo; Liu, Feng; Wang, Wei

    2003-12-01

    The occurrence of synchronized oscillation and its critical behavior in a globally coupled stochastic Hodgkin-Huxley (HH) neuronal network are studied in this paper. It is found that there is a critical curve for the coupling strength versus noise intensity, which shows a V-shaped structure and divides the network behavior into an asynchronous firing state and a synchronous one. Analysis of the scaling behavior near the bifurcation point reveals that this transition is analogous to a second-order phase transition. The frequency of synchronized oscillations is within the range of 40-80 Hz, and its physical origin is explored by studying single HH neuron’s impedance. The intrinsic property of single neuron may account for the generation and the frequency characteristics of synchronized rhythmic oscillations.

  3. Linear oscillations of a supported bubble or drop

    NASA Astrophysics Data System (ADS)

    Vejrazka, Jiri; Vobecka, Lucie; Tihon, Jaroslav

    2013-06-01

    Shape oscillations of a spherical bubble or drop, for which part of its interface is fixed due to contact with a solid support, are studied analytically using variational methods. Linear oscillations and irrotational flow are assumed. The present analysis is parallel to those of Strani and Sabetta ["Free vibrations of a drop in partial contact with a solid support," J. Fluid Mech. 141, 233-247 (1984)], 10.1017/S0022112084000811; and Bostwick and Steen ["Capillary oscillations of a constrained liquid drop," Phys. Fluids 21, 032108 (2009)], 10.1063/1.3103344 but is also able to determine the response of bubbles or drops to movements imposed on their supports or to variations of their volumes. The analysis leads to equations of motion with a simple structure, from which the eigenmodes and frequency response to periodic forcing are easily determined.

  4. A tunnel-diode oscillator with an SAW resonator

    NASA Astrophysics Data System (ADS)

    Kmita, A. M.; Kundin, A. P.; Maltsev, O. A.

    1984-03-01

    Experiments were conducted to investigate the effect of changes in the bias voltage on the frequency of a tunnel-diode oscillator stabilized by a surface-acoustic-wave resonator. For an oscillator with a parallel resonance frequency of 78.901 MHz, a change in the bias voltage from 0.15 to 0.54 V produces a 4-percent change in the generation frequency. The frequency instability is described by an N-shaped curve, which is attributed to the effect of higher harmonics. However, in the bias voltage range 0.226-0.372, the frequency instability of the oscillator does not exceed 2 x 10 to the -4th.

  5. Longitudinal oscillation of launch vehicles

    NASA Technical Reports Server (NTRS)

    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.

  6. Fano Interference in Classical Oscillators

    ERIC Educational Resources Information Center

    Satpathy, S.; Roy, A.; Mohapatra, A.

    2012-01-01

    We seek to illustrate Fano interference in a classical coupled oscillator by using classical analogues of the atom-laser interaction. We present an analogy between the dressed state picture of coherent atom-laser interaction and a classical coupled oscillator. The Autler-Townes splitting due to the atom-laser interaction is analogous to the…

  7. Mechanical Parametric Oscillations and Waves

    ERIC Educational Resources Information Center

    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…

  8. The ratios of partition functions at different temperatures - Sensitivity to potential energy shape II

    NASA Astrophysics Data System (ADS)

    Buchowiecki, Marcin

    2016-05-01

    The ratios of partition functions at different temperatures are calculated and its dependence on potential energy shape is analyzed. The role of anharmonicity and non-rigidity of rotations is discussed in the context of the angular frequency and the shape of potential energy curve. A role of inflection point of potential energy curve for the quality of rigid rotor harmonic oscillator and rigid rotor Morse oscillator is elucidated.

  9. An algebraic cluster model based on the harmonic oscillator basis

    NASA Technical Reports Server (NTRS)

    Levai, Geza; Cseh, J.

    1995-01-01

    We discuss the semimicroscopic algebraic cluster model introduced recently, in which the internal structure of the nuclear clusters is described by the harmonic oscillator shell model, while their relative motion is accounted for by the Vibron model. The algebraic formulation of the model makes extensive use of techniques associated with harmonic oscillators and their symmetry group, SU(3). The model is applied to some cluster systems and is found to reproduce important characteristics of nuclei in the sd-shell region. An approximate SU(3) dynamical symmetry is also found to hold for the C-12 + C-12 system.

  10. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.

    1978-01-01

    A number of 401.2 MHz surface acoustic wave (SAW) controlled oscillators were built and tested. The performance of these oscillators was evaluated for possible use as stable oscillators in communication systems. A short term frequency stability of better than 1 x 10 to the minus 9th power for one second was measured for the SAW oscillators. Long term frequency drift was measured and was found to be dependent on SAW design and packaging. Drift rates ranging from 15 ppm in twenty weeks to 2.5 ppm in twenty weeks were observed. Some further improvement was required. The temperature dependence of the saw oscillators was evaluated and it was concluded that some form of temperature compensation will be necessary to meet the requirements of some communication systems.

  11. Surface acoustic wave stabilized oscillators

    NASA Technical Reports Server (NTRS)

    Parker, T. E.; Lee, D. L.; Leja, I.

    1979-01-01

    Four areas of surface acoustic wave (SAW) controlled oscillators were investigated and a number of 401.2 MHz oscillators were constructed that showed improved performance. Aging studies on SAW devices packaged in HC36/U cold weld enclosures produced frequency drifts as low as 0.4 ppm in 35 weeks and drift rates well under 0.5 ppm/year. Temperature compensation circuits have substantially improved oscillator temperature stability, with a deviation of + or - 4 ppm observed over the range -45 C to + 40 C. High efficiency amplifiers were constructed for SAW oscillators and a dc to RF efficiency of 44 percent was obtained for an RF output of 25 mW. Shock and vibration tests were made on four oscillators and all survived 500 G shock pulses unchanged. Only when white noise vibration (20 Hz to 2000 Hz) levels of 20 G's rms were applied did some of the devices fail.

  12. Progress in optical parametric oscillators

    NASA Technical Reports Server (NTRS)

    Fan, Y. X.; Byer, R. L.

    1984-01-01

    It is pointed out that tunable coherent sources are very useful for many applications, including spectroscopy, chemistry, combustion diagnostics, and remote sensing. Compared with other tunable sources, optical parametric oscillators (OPO) offer the potential advantage of a wide wavelength operating range, which extends from 0.2 micron to 25 microns. The current status of OPO is examined, taking into account mainly advances made during the last decade. Attention is given to early LiNbO3 parametric oscillators, problems which have prevented wide use of parametric oscillators, the demonstration of OPO's using urea and AgGaS2, progress related to picosecond OPO's, a breakthrough in nanosecond parametric oscillators, the first demonstration of a waveguide and fiber parametric amplification and generation, the importance of chalcopyrite crystals, and theoretical work performed with the aim to understand the factors affecting the parametric oscillator performance.

  13. Panofsky Prize Lecture: Evidence for Oscillation of Atmospheric Neutrinos

    NASA Astrophysics Data System (ADS)

    Totsuka, Yoji

    2002-04-01

    Atmospheric neutrinos are decay products of pions and kaons (and of their decay products muons) produced by nuclear interactions of cosmic rays with air nuclei. Though their flux is not known well, only within 20 %, physics quantities that are independent of the flux uncertainty exist. The ratio of the number of muon neutrinos to the number of electron neutrinos is estimated to be accurate within 5 %. The other quantity is the shape of the zenith-angle distribution. Kamiokande and Super-Kamiokande are water Cherenkov detectors with 3,000 ton and 50,000 ton pure water, respectively. Kamiokande was operational in 1983 - 1996, and Super-K in 1996 - 2001 and 2003 - in future. We had already noted in 1988 that the observed μ/e ratio, which represented ν_mu/ν_e, was smaller by about 40 %. Later in 1994 we noted that the zenith angle distribution of muon neutrinos was strongly distorted, namely much fewer muons observed in the upward direction, while downward-going muons were what we expected. Electrons were quite normal. In 1996 Super-Kamiokande was ready. Its fiducial volume is 22.5 kton, much larger than Kamiokande's 1.04 kton. In 1998 based on 25.5 kton years of data we presented convincing results on the small μ/e ratio which was caused by fewer number of muons in the upward direction. The essential feature of the observed anomaly was that the disappearance of muon neutrinos depended strongly on their path length and on their energies. Electrons showed no anomaly within the experimental limit. These results were quantitatively and almost uniquely explained by oscillation of muon neutrinos to tau neutrinos, thus evidence for the finite but tiny mass of neutrinos.

  14. Neutrino mass hierarchy and precision physics with medium-baseline reactors: Impact of energy-scale and flux-shape uncertainties

    NASA Astrophysics Data System (ADS)

    Capozzi, F.; Lisi, E.; Marrone, A.

    2015-11-01

    Nuclear reactors provide intense sources of electron antineutrinos, characterized by few-MeV energy E and unoscillated spectral shape Φ (E ). High-statistics observations of reactor neutrino oscillations over medium-baseline distances L ˜O (50 ) km would provide unprecedented opportunities to probe both the long-wavelength mass-mixing parameters (δ m2 and θ12) and the short-wavelength ones (Δ mee 2 and θ13), together with the subtle interference effects associated with the neutrino mass hierarchy (either normal or inverted). In a given experimental setting—here taken as in the JUNO project for definiteness—the achievable hierarchy sensitivity and parameter accuracy depend not only on the accumulated statistics but also on systematic uncertainties, which include (but are not limited to) the mass-mixing priors and the normalizations of signals and backgrounds. We examine, in addition, the effect of introducing smooth deformations of the detector energy scale, E →E'(E ), and of the reactor flux shape, Φ (E )→Φ'(E ), within reasonable error bands inspired by state-of-the-art estimates. It turns out that energy-scale and flux-shape systematics can noticeably affect the performance of a JUNO-like experiment, both on the hierarchy discrimination and on precision oscillation physics. It is shown that a significant reduction of the assumed energy-scale and flux-shape uncertainties (by, say, a factor of 2) would be highly beneficial to the physics program of medium-baseline reactor projects. Our results also shed some light on the role of the inverse-beta decay threshold, of geoneutrino backgrounds, and of matter effects in the analysis of future reactor oscillation data.

  15. A theory of generalized Bloch oscillations

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

    Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics.

  16. Relaxation damping in oscillating contacts

    PubMed Central

    Popov, M.; Popov, V.L.; Pohrt, R.

    2015-01-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed. PMID:26549011

  17. Relaxation damping in oscillating contacts

    NASA Astrophysics Data System (ADS)

    Popov, M.; Popov, V. L.; Pohrt, R.

    2015-11-01

    If a contact of two purely elastic bodies with no sliding (infinite coefficient of friction) is subjected to superimposed oscillations in the normal and tangential directions, then a specific damping appears, that is not dependent on friction or dissipation in the material. We call this effect “relaxation damping”. The rate of energy dissipation due to relaxation damping is calculated in a closed analytic form for arbitrary axially-symmetric contacts. In the case of equal frequency of normal and tangential oscillations, the dissipated energy per cycle is proportional to the square of the amplitude of tangential oscillation and to the absolute value of the amplitude of normal oscillation, and is dependent on the phase shift between both oscillations. In the case of low frequency tangential oscillations with superimposed high frequency normal oscillations, the dissipation is proportional to the ratio of the frequencies. Generalization of the results for macroscopically planar, randomly rough surfaces as well as for the case of finite friction is discussed.

  18. Jarzynski equality in van der Pol and Rayleigh oscillators

    NASA Astrophysics Data System (ADS)

    Hasegawa, Hideo

    2011-12-01

    We have studied the Jarzynski equality (JE) in van der Pol and Rayleigh oscillators, which are typical deterministic non-Hamiltonian models but not expected to rigorously satisfy the JE because they are not reversible. Our simulations that calculate the contribution to the work W of an applied ramp force with a duration τ show that the JE approximately holds for a fairly wide range of τ including τ→0 and τ→∞, except for τ˜T, where T denotes the period of relaxation oscillations in the limit cycle. The work distribution function (WDF) is shown to be non-Gaussian with the U-shaped structure for a strong damping parameter. The τ dependence of R (=-kBTln) obtained by our simulations is semiquantitatively elucidated with the use of a simple expression for limit-cycle oscillations, where the bracket <·> expresses an average over the WDF. The result obtained in self-excited oscillators is in contrast with the fact that the JE holds in the Nosé-Hoover oscillator, which also belongs to deterministic non-Hamiltonian models.

  19. Flame oscillations in tubes with nonslip at the walls

    SciTech Connect

    Akkerman, V'yacheslav; Bychkov, Vitaly; Petchenko, Arkady; Eriksson, Lars-Erik

    2006-06-15

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

  20. Endogenous Cortical Oscillations Constrain Neuromodulation by Weak Electric Fields

    PubMed Central

    Schmidt, Stephen L.; Iyengar, Apoorva K.; Foulser, A. Alban; Boyle, Michael R.; Fröhlich, Flavio

    2014-01-01

    Background Transcranial alternating current stimulation (tACS) is a non-invasive brain stimulation modality that may modulate cognition by enhancing endogenous neocortical oscillations with the application of sine-wave electric fields. Yet, the role of endogenous network activity in enabling and shaping the effects of tACS has remained unclear. Objective We combined optogenetic stimulation and multichannel slice electrophysiology to elucidate how the effect of weak sine-wave electric field depends on the ongoing cortical oscillatory activity. We hypothesized that the structure of the response to stimulation depended on matching the stimulation frequency to the endogenous cortical oscillation. Methods We studied the effect of weak sine-wave electric fields on oscillatory activity in mouse neocortical slices. Optogenetic control of the network activity enabled the generation of in vivo like cortical oscillations for studying the temporal relationship between network activity and sine-wave electric field stimulation. Results Weak electric fields enhanced endogenous oscillations but failed to induce a frequency shift of the ongoing oscillation for stimulation frequencies that were not matched to the endogenous oscillation. This constraint on the effect of electric field stimulation imposed by endogenous network dynamics was limited to the case of weak electric fields targeting in vivo-like network dynamics. Together, these results suggest that the key mechanism of tACS may be enhancing but not overriding of intrinsic network dynamics. Conclusion Our results contribute to understanding the inconsistent tACS results from human studies and propose that stimulation precisely adjusted in frequency to the endogenous oscillations is key to rational design of non-invasive brain stimulation paradigms. PMID:25129402

  1. Theory of Mitotic Spindle Oscillations

    NASA Astrophysics Data System (ADS)

    Grill, Stephan W.; Kruse, Karsten; Jülicher, Frank

    2005-03-01

    During unequal cell division the mitotic spindle is positioned away from the center of the cell before cell cleavage. In many biological systems this repositioning is accompanied by oscillatory movements of the spindle. We present a theoretical description for mitotic spindle oscillations. We show that the cooperative attachment and detachment of cortical force generators to astral microtubules leads to spontaneous oscillations beyond a critical number of force generators. This mechanism can quantitatively describe the spindle oscillations observed during unequal division of the one cell stage Caenorhabditis elegans embryo.

  2. VOLTAGE-CONTROLLED TRANSISTOR OSCILLATOR

    DOEpatents

    Scheele, P.F.

    1958-09-16

    This patent relates to transistor oscillators and in particular to those transistor oscillators whose frequencies vary according to controlling voltages. A principal feature of the disclosed transistor oscillator circuit resides in the temperature compensation of the frequency modulating stage by the use of a resistorthermistor network. The resistor-thermistor network components are selected to have the network resistance, which is in series with the modulator transistor emitter circuit, vary with temperature to compensate for variation in the parameters of the transistor due to temperature change.

  3. Forced synchronization of quasiperiodic oscillations

    NASA Astrophysics Data System (ADS)

    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. Analyzing Atmospheric Neutrino Oscillations

    SciTech Connect

    Escamilla, J.; Ernst, D. J.; Latimer, D. C.

    2007-10-26

    We provide a pedagogic derivation of the formula needed to analyze atmospheric data and then derive, for the subset of the data that are fully-contained events, an analysis tool that is quantitative and numerically efficient. Results for the full set of neutrino oscillation data are then presented. We find the following preliminary results: 1.) the sub-dominant approximation provides reasonable values for the best fit parameters for {delta}{sub 32}, {theta}{sub 23}, and {theta}{sub 13} but does not quantitatively provide the errors for these three parameters; 2.) the size of the MSW effect is suppressed in the sub-dominant approximation; 3.) the MSW effect reduces somewhat the extracted error for {delta}{sub 32}, more so for {theta}{sub 23} and {theta}{sub 13}; 4.) atmospheric data alone constrains the allowed values of {theta}{sub 13} only in the sub-dominant approximation, the full three neutrino calculations requires CHOOZ to get a clean constraint; 5.) the linear in {theta}{sub 13} terms are not negligible; and 6.) the minimum value of {theta}{sub 13} is found to be negative, but at a statistically insignificant level.

  5. Sawtooth oscillation in tokamaks

    SciTech Connect

    Park, W.; Monticello, D.A.

    1989-03-01

    A three-dimensional nonlinear toroidal full MHD code, MH3D, has been used to study sawtooth oscillations in tokamaks. The profile evolution during the sawtooth crash phase compares well with experiment, but only if neoclassical resistivity is used in the rise phase. (Classical resistivity has been used in most of the previous theoretical sawtooth studies.) With neoclassical resistivity, the q value at the axis drops from 1 to about 0.8 before the crash phase, and then resets to 1 through a Kadomtsev-type complete reconnection process. This ..delta..q/sub 0/ approx. = 0.2 is much larger than ..delta..q/sub o/ approx. = 0.01, which is obtained if classical resistivity is used. The current profile is strongly peaked at the axis with a flat region around the singular surface, and is similar to the Textor profile. To understand this behavior, approximate formulas for the time behavior of current and q values are derived. A functional dependence of sawtooth period scaling is also derived. A semi-empirical scaling is found which fits the experimental data from various tokamaks. Some evidence is presented which indicates that the fast crash time is due to enhanced effective resistivity inside the singular current sheet, generated by, e.g., microinstability and electron parallel viscosity with stochastic fields at the x-point. 16 refs., 5 figs.

  6. Collective neutrino oscillations in nonspherical geometry

    SciTech Connect

    Dasgupta, Basudeb; Dighe, Amol; Mirizzi, Alessandro; Raffelt, Georg

    2008-08-01

    The rich phenomenology of collective neutrino oscillations has been studied only in one-dimensional or spherically symmetric systems. Motivated by the nonspherical example of coalescing neutron stars, presumably the central engines of short gamma-ray bursts, we use the Liouville equation to formulate the problem for general source geometries. Assuming the neutrino ensemble displays self-maintained coherence, the problem once more becomes effectively one-dimensional along the streamlines of the overall neutrino flux. This approach for the first time provides a formal definition of the 'single-angle approximation' frequently used for supernova neutrinos and allows for a natural generalization to nonspherical geometries. We study the explicit example of a disk-shaped source as a proxy for coalescing neutron stars.

  7. Spontaneous mechanical oscillations: implications for developing organisms.

    PubMed

    Kruse, Karsten; Riveline, Daniel

    2011-01-01

    Major transformations of cells during embryonic development are traditionally associated with the activation or inhibition of genes and with protein modifications. The contributions of mechanical properties intrinsic to the matter an organism is made of, however, are often overlooked. The emerging field "physics of living matter" is addressing active material properties of the cytoskeleton and tissues like the spontaneous generation of stress, which may lead to shape changes and tissue flows, and their implications for embryonic development. Here, we discuss spontaneous mechanical oscillations to present some basic elements for understanding this physics, and we illustrate its application to developing embryos. We highlight the role of state diagrams to quantitatively probe the significance of the corresponding physical concepts for understanding development. PMID:21501749

  8. Peniotron oscillations in rising sun cavity

    SciTech Connect

    Gallagher, D.; Richards, J.; Scafuri, F.; Armstrong, C.

    1995-12-31

    For the first time ever, peniotron oscillations have been observed from a peniotron oscillator operating at the f=4f{sub c} harmonic at 90 GHz and in a rising-sun magnetron-type waveguide circuit. The experiment was designed to achieve proof of principle at low power for the rising-sun circuit. The beam voltage and current were 9 kV and 0.3 A, respectively. Preliminary results show 65% beam transmission to the collector. The output power achieved was 5 watts. Output power was observed for beam voltages from 7 to over 9 kV. Performance optimization will be achieved by magnetic tuning and shimming. Also to improve on the output power, greater field stability and control of the magnetic field shape will be necessary. Computer controlled power supplies for each of the individual magnetic coils were placed on order. Presented will be the cold-test and optimized hot-test data and how they correlate to simulated performance to determine beam quality. Presented also will be a description of the gun, circuit and RF window, as well as a high power experiment planned for later this year.

  9. Global Seismic Oscillations in Soft Gamma Repeaters

    NASA Astrophysics Data System (ADS)

    Duncan, Robert C.

    1998-05-01

    There is evidence that soft gamma repeaters (SGRs) are neutron stars that experience frequent starquakes, possibly driven by an evolving, ultrastrong magnetic field. The empirical power-law distribution of SGR burst energies, analogous to the Gutenberg-Richter law for earthquakes, exhibits a turnover at high energies, consistent with a global limit on the crust fracture size. With such large starquakes occurring, the significant excitation of global seismic oscillations (GSOs) seems likely. Moreover, GSOs may be self-exciting in a stellar crust that is strained by many randomly oriented stresses. We explain why low-order toroidal modes, which preserve the shape of the star and have observable frequencies as low as ~30 Hz, may be especially susceptible to excitation. We estimate the eigenfrequencies as a function of stellar mass and radius, as well as their magnetic and rotational shiftings/splittings. We also describe ways in which these modes might be detected and damped. There is marginal evidence for 23 ms oscillations in the hard initial pulse of the 1979 March 5 event. This could be due to the 3t0 mode in a neutron star with B~1014 G or less, or it could be the fundamental toroidal mode if the field in the deep crust of SGR 0526-66 is ~4×1015 G, in agreement with other evidence. If confirmed, GSOs would give corroborating evidence for crust-fracturing magnetic fields in SGRs: B>~1014 G.

  10. NUCLEAR REACTOR

    DOEpatents

    Anderson, C.R.

    1962-07-24

    A fluidized bed nuclear reactor and a method of operating such a reactor are described. In the design means are provided for flowing a liquid moderator upwardly through the center of a bed of pellets of a nentron-fissionable material at such a rate as to obtain particulate fluidization while constraining the lower pontion of the bed into a conical shape. A smooth circulation of particles rising in the center and falling at the outside of the bed is thereby established. (AEC)

  11. Fragment oriented molecular shapes.

    PubMed

    Hain, Ethan; Camacho, Carlos J; Koes, David Ryan

    2016-05-01

    Molecular shape is an important concept in drug design and virtual screening. Shape similarity typically uses either alignment methods, which dynamically optimize molecular poses with respect to the query molecular shape, or feature vector methods, which are computationally less demanding but less accurate. The computational cost of alignment can be reduced by pre-aligning shapes, as is done with the Volumetric-Aligned Molecular Shapes (VAMS) method. Here, we introduce and evaluate fragment oriented molecular shapes (FOMS), where shapes are aligned based on molecular fragments. FOMS enables the use of shape constraints, a novel method for precisely specifying molecular shape queries that provides the ability to perform partial shape matching and supports search algorithms that function on an interactive time scale. When evaluated using the challenging Maximum Unbiased Validation dataset, shape constraints were able to extract significantly enriched subsets of compounds for the majority of targets, and FOMS matched or exceeded the performance of both VAMS and an optimizing alignment method of shape similarity search. PMID:27085751

  12. The Hue of Shapes

    ERIC Educational Resources Information Center

    Albertazzi, Liliana; Da Pos, Osvaldo; Canal, Luisa; Micciolo, Rocco; Malfatti, Michela; Vescovi, Massimo

    2013-01-01

    This article presents an experimental study on the naturally biased association between shape and color. For each basic geometric shape studied, participants were asked to indicate the color perceived as most closely related to it, choosing from the Natural Color System Hue Circle. Results show that the choices of color for each shape were not…

  13. The Shape of Thought

    ERIC Educational Resources Information Center

    Markson, Lori; Diesendruck, Gil; Bloom, Paul

    2008-01-01

    When children learn the name of a novel object, they tend to extend that name to other objects similar in shape--a phenomenon referred to as the shape bias. Does the shape bias stem from learned associations between names and categories of objects, or does it derive from more general properties of children's understanding of language and the…

  14. Complex Dynamics in a Duffing-Van der Pol Oscillator with φ6 Potential

    NASA Astrophysics Data System (ADS)

    Yu, Jun; Xie, Zhi-kun; Yu, Li-xian

    2008-11-01

    The dynamical behavior of the extended Duffing-Van der Pol oscillator is investigated numerically in some detail. Different routes to chaos such as period-doubling bifurcation and intermittency, as well as various shapes of strange attractors and rich dynamical phenomena: crisis, transient chaos, are all observed by using bifurcation diagrams, phase projections and Poincaré maps. To characterize chaotic behavior of this oscillator system, the spectrum of Lyapunov exponent and Lyapunov dimension of the strange attractor are also employed.

  15. GENERAL: Period-Doubling Cascades and Strange Attractors in Extended Duffing-Van der Pol Oscillator

    NASA Astrophysics Data System (ADS)

    Yu, Jun; Pan, Wei-Zhen; Zhang, Rong-Bo

    2009-05-01

    The dynamical behavior of the extended Duffing-Van der Pol oscillator is investigated numerically in detail. With the aid of some numerical simulation tools such as bifurcation diagrams and Poincaré maps, the different routes to chaos and various shapes of strange attractors are observed. To characterize chaotic behavior of this oscillator system, the spectrum of Lyapunov exponent and Lyapunov dimension are also employed.

  16. Multiple-beam pulse shaping and preamplification

    SciTech Connect

    Wilcox, R.B.; VanWonterghem, B.W.; Burkhart, S.C.; Davin, J.M.

    1994-11-09

    Glass fusion laser systems typically use a master oscillator-power amplifier (MOPA) architecture, where control of the optical pulse temporal and spatial parameters is accomplished mainly in the master oscillator and low power optics. The pulses from this low power ``front end`` are amplified in the power amplifier, which modifies the pulse shape temporally and spatially. Nonlinear frequency conversion crystals following the amplifier further change the pulse before it reaches the target. To effectively control the optical pulse on target for different types of experiments, and compensate for nonlinearity in the preceding optics, the front end system must be versatile enough to easily control many pulse parameters over a large range. The front end pulse generation system described in this article represents a new approach to this problem. The proposed National Ignition Facility (NIF) has 192 beamlines, each of which requires an input pulse of up to 12 Joules in around 4 ns equivalent square pulse length. Considerations of laser architecture for supplying each of these beamlines from a central oscillator system were crucial in the design of the front end. Previous lasers have used bulk optics to split a single oscillator signal and report beams to multiple amplifier chains. A key idea in the current design is to replace bulk optic transport with fibers, eliminating large opto-mechanical subsystems. Another important concept is convenient pulse forming using low voltage integrated optic modulators. The integrated optic and fiber optic concepts resulted in the current pulse generation designs for NEF. An important advantage is that each of the beamlines can have an independently controlled temporal pulse shape, which provides for precise balance of instantaneous power on target.

  17. Dynamics of hierarchical Brownian oscillators

    NASA Astrophysics Data System (ADS)

    Knapp, E. W.

    1988-11-01

    Two hierarchical Brownian oscillator models are introduced by using a discretized Brownian oscillator model. The dynamical behavior of these models is solved exactly. Closed-form expressions for the intermediate scattering function and the energy relaxation function governing the frequency-dependent specific heat are given. A general relationship between the two relaxation functions is established. The case of a rectangular distribution of activation energies for the different hierarchy levels of the oscillator is considered in more detail. There the energy relaxation function decays with a logarithmic slope and the intermediate scattering function exhibits an algebraic long-time decay. The two hierarchical Brownian oscillator models have the same dynamical behavior though they possess a quite different coupling scheme.

  18. Brain oscillations in neuropsychiatric disease.

    PubMed

    Başar, Erol

    2013-09-01

    The term "brain (or neural) oscillations" refers to the rhythmic and/or repetitive electrical activity generated spontaneously and in response to stimuli by neural tissue in the central nervous system. The importance of brain oscillations in sensory-cognitive processes has become increasingly evident. It has also become clear that event-related oscillations are modified in many types of neuropathology, in particular in cognitive impairment. This review discusses methods such as evoked/event-related oscillations and spectra, coherence analysis, and phase locking. It gives examples of applications of essential methods and concepts in bipolar disorder that provide a basis for fundamental notions regarding neurophysiologic biomarkers in cognitive impairment. The take-home message is that in the development of diagnostic and pharmacotherapeutic strategies, neurophysiologic data should be analyzed in a framework that uses a multiplicity of methods and frequency bands. PMID:24174901

  19. Transient voltage oscillations in coils

    SciTech Connect

    Chowdhuri, P.

    1985-01-01

    Magnet coils may be excited into internal voltage oscillations by transient voltages. Such oscillations may electrically stress the magnet's dielectric components to many times its normal stress. This may precipitate a dielectric failure, and the attendant prolonged loss of service and costly repair work. Therefore, it is important to know the natural frequencies of oscillations of a magnet during the design stage, and to determine whether the expected switching transient voltages can excite the magnet into high-voltage internal oscillations. The series capacitance of a winding significantly affects its natural frequencies. However, the series capacitance is difficult to calculate, because it may comprise complex capacitance network, consisting of intra- and inter-coil turn-to-turn capacitances of the coil sections. A method of calculating the series capacitance of a winding is proposed. This method is rigorous but simple to execute. The time-varying transient voltages along the winding are also calculated.

  20. Oscillations emerging from noise-driven steady state in networks with electrical synapses and subthreshold resonance

    PubMed Central

    Tchumatchenko, Tatjana; Clopath, Claudia

    2014-01-01

    Oscillations play a critical role in cognitive phenomena and have been observed in many brain regions. Experimental evidence indicates that classes of neurons exhibit properties that could promote oscillations, such as subthreshold resonance and electrical gap junctions. Typically, these two properties are studied separately but it is not clear which is the dominant determinant of global network rhythms. Our aim is to provide an analytical understanding of how these two effects destabilize the fluctuation-driven state, in which neurons fire irregularly, and lead to an emergence of global synchronous oscillations. Here we show how the oscillation frequency is shaped by single neuron resonance, electrical and chemical synapses.The presence of both gap junctions and subthreshold resonance are necessary for the emergence of oscillations. Our results are in agreement with several experimental observations such as network responses to oscillatory inputs and offer a much-needed conceptual link connecting a collection of disparate effects observed in networks. PMID:25405458

  1. Results from Neutrino Oscillations Experiments

    SciTech Connect

    Aguilar-Arevalo, Alexis

    2010-09-10

    The interpretation of the results of early solar and atmospheric neutrino experiments in terms of neutrino oscillations has been verified by several recent experiments using both, natural and man-made sources. The observations provide compelling evidence in favor of the existence of neutrino masses and mixings. These proceedings give a general description of the results from neutrino oscillation experiments, the current status of the field, and some possible future developments.

  2. Wavelet Analysis of Umbral Oscillations

    NASA Astrophysics Data System (ADS)

    Christopoulou, E. B.; Skodras, A.; Georgakilas, A. A.; Koutchmy, S.

    2003-07-01

    We study the temporal behavior of the intensity and velocity chromospheric umbral oscillations, applying wavelet analysis techniques to four sets of observations in the Hα line and one set of simultaneous observations in the Hα and the nonmagnetic Fe I (5576.099 Å) line. The wavelet and Fourier power spectra of the intensity and the velocity at chromospheric levels show both 3 and 5 minute oscillations. Oscillations in the 5 minute band are prominent in the intensity power spectra; they are significantly reduced in the velocity power spectra. We observe multiple peaks of closely spaced cospatial frequencies in the 3 minute band (5-8 mHz). Typically, there are three oscillating modes present: (1) a major one near 5.5 mHz, (2) a secondary near 6.3 mHz, and (3) oscillations with time-varying frequencies around 7.5 mHz that are present for limited time intervals. In the frame of current theories, the oscillating mode near 5.5 mHz should be considered as a fingerprint of the photospheric resonator, while the other two modes can be better explained by the chromospheric resonator. The wavelet spectra show a dynamic temporal behavior of the 3 minute oscillations. We observed (1) frequency drifts, (2) modes that are stable over a long time and then fade away or split up into two oscillation modes, and (3) suppression of frequencies for short time intervals. This behavior can be explained by the coupling between modes closely spaced in frequency or/and by long-term variations of the driving source of the resonators. Based on observations performed on the National Solar Observatory/Sacramento Peak Observatory Richard B. Dunn Solar Telescope (DST) and on the Big Bear Solar Observatory Harold Zirin Telescope.

  3. DETECTING BARYON ACOUSTIC OSCILLATIONS

    SciTech Connect

    Labatie, A.; Starck, J. L.

    2012-02-20

    Baryon acoustic oscillations (BAOs) are a feature imprinted in the galaxy distribution by acoustic waves traveling in the plasma of the early universe. Their detection at the expected scale in large-scale structures strongly supports current cosmological models with a nearly linear evolution from redshift z Almost-Equal-To 1000 and the existence of dark energy. In addition, BAOs provide a standard ruler for studying cosmic expansion. In this paper, we focus on methods for BAO detection using the correlation function measurement {xi}-hat. For each method, we want to understand the tested hypothesis (the hypothesis H{sub 0} to be rejected) and the underlying assumptions. We first present wavelet methods which are mildly model-dependent and mostly sensitive to the BAO feature. Then we turn to fully model-dependent methods. We present the method used most often based on the {chi}{sup 2} statistic, but we find that it has limitations. In general the assumptions of the {chi}{sup 2} method are not verified, and it only gives a rough estimate of the significance. The estimate can become very wrong when considering more realistic hypotheses, where the covariance matrix of {xi}-hat depends on cosmological parameters. Instead, we propose to use the {Delta}l method based on two modifications: we modify the procedure for computing the significance and make it rigorous, and we modify the statistic to obtain better results in the case of varying covariance matrix. We verify with simulations that correct significances are different from the ones obtained using the classical {chi}{sup 2} procedure. We also test a simple example of varying covariance matrix. In this case we find that our modified statistic outperforms the classical {chi}{sup 2} statistic when both significances are correctly computed. Finally, we find that taking into account variations of the covariance matrix can change both BAO detection levels and cosmological parameter constraints.

  4. Nonadiabatic Van der Pol oscillations in molecular transport

    NASA Astrophysics Data System (ADS)

    Kartsev, Alexey; Verdozzi, Claudio; Stefanucci, Gianluca

    2014-01-01

    The force exerted by the electrons on the nuclei of a current-carrying molecular junction can be manipulated to engineer nanoscale mechanical systems. In the adiabatic regime a peculiarity of these forces is negative friction, responsible for Van der Pol oscillations of the nuclear coordinates. In this work we study the robustness of the Van der Pol oscillations against high-frequency sources. For this purpose we go beyond the adiabatic approximation and perform full Ehrenfest dynamics simulations. The numerical scheme implements a mixed quantum-classical algorithm for open systems and is capable to deal with arbitrary time-dependent driving fields. We find that the Van der Pol oscillations are extremely stable. The nonadiabatic electron dynamics distorts the trajectory in the momentum-coordinate phase space but preserves the limit cycles in an average sense. We further show that high-frequency fields change both the oscillation amplitudes and the average nuclear positions. By switching the fields off at different times one obtains cycles of different amplitudes which attain the limit cycle only after considerably long times.

  5. Calculation of four-particle harmonic-oscillator transformation brackets

    NASA Astrophysics Data System (ADS)

    Germanas, D.; Kalinauskas, R. K.; Mickevičius, S.

    2010-02-01

    A procedure for precise calculation of the three- and four-particle harmonic-oscillator (HO) transformation brackets is presented. The analytical expressions of the four-particle HO transformation brackets are given. The computer code for the calculations of HO transformation brackets proves to be quick, efficient and produces results with small numerical uncertainties. Program summaryProgram title: HOTB Catalogue identifier: AEFQ_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEFQ_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 1247 No. of bytes in distributed program, including test data, etc.: 6659 Distribution format: tar.gz Programming language: FORTRAN 90 Computer: Any computer with FORTRAN 90 compiler Operating system: Windows, Linux, FreeBSD, True64 Unix RAM: 8 MB Classification: 17.17 Nature of problem: Calculation of the three-particle and four-particle harmonic-oscillator transformation brackets. Solution method: The method is based on compact expressions of the three-particle harmonics oscillator brackets, presented in [1] and expressions of the four-particle harmonics oscillator brackets, presented in this paper. Restrictions: The three- and four-particle harmonic-oscillator transformation brackets up to the e=28. Unusual features: Possibility of calculating the four-particle harmonic-oscillator transformation brackets. Running time: Less than one second for the single harmonic-oscillator transformation bracket. References:G.P. Kamuntavičius, R.K. Kalinauskas, B.R. Barret, S. Mickevičius, D. Germanas, Nuclear Physics A 695 (2001) 191.

  6. Rattleback's Chaotic Oscillations

    NASA Astrophysics Data System (ADS)

    Hanias, M. P.; Stavrinides, S. G.

    The rattleback is a canoe-shaped object with the curious property of spin asymmetry. It provides a prototype of chiral dynamics, wherein lack of mirror-symmetry leads to unconventional dynamics. In this paper dynamics of rattleback are introduced and by applying Kane's model, it is shown that one can construct a realistic mathematical model by assuming rolling without slipping and employing a torque proportional to angular velocity, in order to provide for energy dissipation. Time series analysis is performed following Grassberger-Procaccia method. The time series corresponds to the dependence of yaw, roll and spin angles on time and their corresponding angular velocities. Finally, rattleback's strange attractor's invariant parameters as correlation and minimum embedding dimension, Kolmogorov entropy and Lyapunov exponents, are calculated.

  7. Reversible shape memory

    NASA Astrophysics Data System (ADS)

    Sheiko, Sergei; Zhou, Jing; White, Sarah; Ashby, Valerie

    2012-02-01

    An ``Achilles' heel'' of shape memory materials is that shape transformations triggered by an external stimulus are usually irreversible. Here we present a new concept of reversible transitions between two well-defined shapes by controlling hierarchic crystallization of a dual-network elastomer. The reversibility was demonstrated for different types of shape transformations including rod bending, winding of a helical coil, and widening an aperture. The distinct feature of the reversible shape alterations is that both counter-shapes are infinitely stable at a temperature of exploitation. Shape reversibility is highly desirable property in many practical applications such as non-surgical removal of a previously inserted catheter and handfree wrapping up of an earlier unraveled solar sail on a space shuttle.

  8. General shape optimization capability

    NASA Technical Reports Server (NTRS)

    Chargin, Mladen K.; Raasch, Ingo; Bruns, Rudolf; Deuermeyer, Dawson

    1991-01-01

    A method is described for calculating shape sensitivities, within MSC/NASTRAN, in a simple manner without resort to external programs. The method uses natural design variables to define the shape changes in a given structure. Once the shape sensitivities are obtained, the shape optimization process is carried out in a manner similar to property optimization processes. The capability of this method is illustrated by two examples: the shape optimization of a cantilever beam with holes, loaded by a point load at the free end (with the shape of the holes and the thickness of the beam selected as the design variables), and the shape optimization of a connecting rod subjected to several different loading and boundary conditions.

  9. Magnetically Coupled Magnet-Spring Oscillators

    ERIC Educational Resources Information Center

    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…

  10. Quantum information, oscillations and the psyche

    NASA Astrophysics Data System (ADS)

    Martin, F.; Carminati, F.; Galli Carminati, G.

    2010-05-01

    In this paper, taking the theory of quantum information as a model, we consider the human unconscious, pre-consciousness and consciousness as sets of quantum bits (qubits). We view how there can be communication between these various qubit sets. In doing this we are inspired by the theory of nuclear magnetic resonance. In this way we build a model of handling a mental qubit with the help of pulses of a mental field. Starting with an elementary interaction between two qubits we build two-qubit quantum logic gates that allow information to be transferred from one qubit to the other. In this manner we build a quantum process that permits consciousness to “read” the unconscious and vice versa. The elementary interaction, e.g. between a pre-consciousness qubit and a consciousness one, allows us to predict the time evolution of the pre-consciousness + consciousness system in which pre-consciousness and consciousness are quantum entangled. This time evolution exhibits Rabi oscillations that we name mental Rabi oscillations. This time evolution shows how for example the unconscious can influence consciousness. In a process like mourning the influence of the unconscious on consciousness, as the influence of consciousness on the unconscious, are in agreement with what is observed in psychiatry.

  11. Axisymmetric oscillation modes of a double droplet system

    SciTech Connect

    Ramalingam, Santhosh K.; Basaran, Osman A.

    2010-11-15

    A double droplet system (DDS) consists of a sessile and a pendant drop that are coupled through a liquid filled cylindrical hole in a plate of thickness d. For a small hole radius R, equilibrium shapes of both drops are sections of spheres. While DDSs have a number of applications in microfluidics, a DDS oscillating about its equilibrium state can be used as a fast focusing liquid lens. Here, a DDS consisting of an isothermal, incompressible Newtonian fluid of constant density p and constant viscosity u that is surrounded by a gas is excited by oscillating in time (a) the pressure in the gas surrounding either drop (pressure excitation), (b) the plate perpendicular to its plane (axial excitation), and (c) the hole radius (radial excitation). In contrast to previous works that assumed transient drop shapes are spherical, they are determined here by simulation and used to identify the natural modes of axisymmetric oscillations from resonances observed during frequency sweeps with DDSs for which the combined volume V of the two drops is less than (4/3)πR3. Pressure and axial excitations are found to have identical responses but axial and radial excitations are shown to excite different modes. These modes are compared to those exhibited by single pendant (sessile) drop systems. Specifically, while a single pendant (sessile) drop has one additional oscillation mode compared to a free drop, a DDS is found to exhibit roughly twice as many oscillation modes as a pendant (sessile) drop. The effects of dimensionless volume V/R3, dimensionless plate thickness d/R, and Ohnesorge number Oh =μ/√ρRσ , where σ is the surface tension of the DDS-gas interface, on the resonance frequencies are also investigated.

  12. Axisymmetric oscillation modes of a double droplet system

    DOE PAGESBeta

    Ramalingam, Santhosh K.; Basaran, Osman A.

    2010-11-15

    A double droplet system (DDS) consists of a sessile and a pendant drop that are coupled through a liquid filled cylindrical hole in a plate of thickness d. For a small hole radius R, equilibrium shapes of both drops are sections of spheres. While DDSs have a number of applications in microfluidics, a DDS oscillating about its equilibrium state can be used as a fast focusing liquid lens. Here, a DDS consisting of an isothermal, incompressible Newtonian fluid of constant density p and constant viscosity u that is surrounded by a gas is excited by oscillating in time (a) themore » pressure in the gas surrounding either drop (pressure excitation), (b) the plate perpendicular to its plane (axial excitation), and (c) the hole radius (radial excitation). In contrast to previous works that assumed transient drop shapes are spherical, they are determined here by simulation and used to identify the natural modes of axisymmetric oscillations from resonances observed during frequency sweeps with DDSs for which the combined volume V of the two drops is less than (4/3)πR3. Pressure and axial excitations are found to have identical responses but axial and radial excitations are shown to excite different modes. These modes are compared to those exhibited by single pendant (sessile) drop systems. Specifically, while a single pendant (sessile) drop has one additional oscillation mode compared to a free drop, a DDS is found to exhibit roughly twice as many oscillation modes as a pendant (sessile) drop. The effects of dimensionless volume V/R3, dimensionless plate thickness d/R, and Ohnesorge number Oh =μ/√ρRσ , where σ is the surface tension of the DDS-gas interface, on the resonance frequencies are also investigated.« less

  13. Fluorescence spectra shape based dynamic thermometry

    NASA Astrophysics Data System (ADS)

    Liu, Liwang; Creten, Sebastiaan; Firdaus, Yuliar; Agustin Flores Cuautle, Jose Jesus; Kouyaté, Mansour; Van der Auweraer, Mark; Glorieux, Christ

    2014-01-01

    An entirely optical, dynamic thermometry technique based on the temperature dependence of a fluorescence spectrum is presented. Different from conventional intensity-based fluorescence thermometry, in this work, neural network recognition is employed to extract the sample temperature from the magnitude and shape of recorded fluorescence spectra. As a demonstration to determine the depth profile of dynamical temperature variations and of the thermal and optical properties of semitransparent samples, in-depth photothermally induced periodical temperature oscillations of a rhodamine B and copper chloride dyed glycerol sample were measured with an accuracy of 4.2 mK.Hz-1/2 and fitted well by a 1D thermal diffusion model.

  14. Damping of prominence longitudinal oscillations due to mass accretion

    NASA Astrophysics Data System (ADS)

    Ruderman, Michael S.; Luna, Manuel

    2016-06-01

    We study the damping of longitudinal oscillations of a prominence thread caused by the mass accretion. We suggested a simple model describing this phenomenon. In this model we considered a thin curved magnetic tube filled with the plasma. The prominence thread is in the central part of the tube and it consists of dense cold plasma. The parts of the tube at the two sides of the thread are filled with hot rarefied plasma. We assume that there are flows of rarefied plasma toward the thread caused by the plasma evaporation at the magnetic tube footpoints. Our main assumption is that the hot plasma is instantaneously accommodated by the thread when it arrives at the thread, and its temperature and density become equal to those of the thread. Then we derive the system of ordinary differential equations describing the thread dynamics. We solve this system of ordinary differential equations in two particular cases. In the first case we assume that the magnetic tube is composed of an arc of a circle with two straight lines attached to its ends such that the whole curve is smooth. A very important property of this model is that the equations describing the thread oscillations are linear for any oscillation amplitude. We obtain the analytical solution of the governing equations. Then we obtain the analytical expressions for the oscillation damping time and periods. We find that the damping time is inversely proportional to the accretion rate. The oscillation periods increase with time. We conclude that the oscillations can damp in a few periods if the inclination angle is sufficiently small, not larger that 10°, and the flow speed is sufficiently large, not less that 30 km s-1. In the second model we consider the tube with the shape of an arc of a circle. The thread oscillates with the pendulum frequency dependent exclusively on the radius of curvature of the arc. The damping depends on the mass accretion rate and the initial mass of the threads, that is the mass of the

  15. Adaptive temperature compensation in circadian oscillations.

    PubMed

    François, Paul; Despierre, Nicolas; Siggia, Eric D

    2012-01-01

    A temperature independent period and temperature entrainment are two defining features of circadian oscillators. A default model of distributed temperature compensation satisfies these basic facts yet is not easily reconciled with other properties of circadian clocks, such as many mutants with altered but temperature compensated periods. The default model also suggests that the shape of the circadian limit cycle and the associated phase response curves (PRC) will vary since the average concentrations of clock proteins change with temperature. We propose an alternative class of models where the twin properties of a fixed period and entrainment are structural and arise from an underlying adaptive system that buffers temperature changes. These models are distinguished by a PRC whose shape is temperature independent and orbits whose extrema are temperature independent. They are readily evolved by local, hill climbing, optimization of gene networks for a common quality measure of biological clocks, phase anticipation. Interestingly a standard realization of the Goodwin model for temperature compensation displays properties of adaptive rather than distributed temperature compensation. PMID:22807663

  16. Adaptive Temperature Compensation in Circadian Oscillations

    PubMed Central

    François, Paul; Despierre, Nicolas; Siggia, Eric D.

    2012-01-01

    A temperature independent period and temperature entrainment are two defining features of circadian oscillators. A default model of distributed temperature compensation satisfies these basic facts yet is not easily reconciled with other properties of circadian clocks, such as many mutants with altered but temperature compensated periods. The default model also suggests that the shape of the circadian limit cycle and the associated phase response curves (PRC) will vary since the average concentrations of clock proteins change with temperature. We propose an alternative class of models where the twin properties of a fixed period and entrainment are structural and arise from an underlying adaptive system that buffers temperature changes. These models are distinguished by a PRC whose shape is temperature independent and orbits whose extrema are temperature independent. They are readily evolved by local, hill climbing, optimization of gene networks for a common quality measure of biological clocks, phase anticipation. Interestingly a standard realization of the Goodwin model for temperature compensation displays properties of adaptive rather than distributed temperature compensation. PMID:22807663

  17. The source of solar oscillations

    NASA Astrophysics Data System (ADS)

    Nigam, R.

    1999-05-01

    In this study the role of line asymmetry and phase difference between velocity and intensity helioseismic spectra for understanding the excitation of solar oscillations is discussed. The solar intensity and velocity oscillations are usually observed from variations in an absorption line. These variations consist of two parts: solar oscillation modes and granulation noise. Because the oscillation modes are excited by granulation, we argue that the granulation signal (noise) is partially correlated with the oscillations. The data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) have clearly revealed a reversal of asymmetry between velocity and intensity power spectra. We have shown that the cause of reversal in asymmetry between velocity and intensity power spectra is due to the presence of the correlated noise in the intensity data. This noise is also responsible for the high-frequency shift in the two spectra at and above the acoustic cutoff frequency. Our theory also explains the deviation of the observed phase difference between velocity and intensity from that predicted by simple adiabatic theory of solar oscillations. The observed phase, jumps in the vicinity of an eigenfrequency, but theory does not explain such jumps. We studied different types of excitation sources at various depths and found that monopole and quadrupole acoustic sources when placed in the superadiabatic layer (at a depth of 75 km below the photosphere) match the observations. For these source types, the sign of the correlation is negative corresponding to photospheric darkening. Finally, an asymmetric fitting formula is used to determine the eigenfrequencies of solar oscillations by fitting both the velocity and intensity power spectra.

  18. The Source of Solar Oscillations

    NASA Astrophysics Data System (ADS)

    Nigam, R.; Kosovichev, A. G.

    1998-12-01

    In this study the role of line asymmetry and phase difference between velocity and intensity helioseismic spectra for understanding the excitation of solar oscillations is discussed. The solar intensity and velocity oscillations are usually observed from variations in an absorption line. These variations consist of two parts: solar oscillation modes and granulation noise. Because the oscillation modes are excited by granulation, we argue that the granulation signal (noise) is partially correlated with the oscillations. The data from the Michelson Doppler Imager (MDI) instrument on board the Solar and Heliospheric Observatory (SOHO) have clearly revealed a reversal of asymmetry between velocity and intensity power spectra. We have shown that the cause of reversal in asymmetry between velocity and intensity power spectra is due to the presence of the correlated noise in the intensity data. This noise is also responsible for the high-frequency shift in the two spectra at and above the acoustic cutoff frequency. Our theory also explains the deviation of the observed phase difference between velocity and intensity from that predicted by simple adiabatic theory of solar oscillations. The observed phase, jumps in the vicinity of an eigenfrequency, but theory does not explain such jumps. We studied different types of excitation sources at various depths and found that monopole and quadrupole acoustic sources when placed in the superadiabatic layer (at a depth of 75 km below the photosphere) match the observations. For these source types, the sign of the correlation is negative corresponding to photospheric darkening. Finally, an asymmetric fitting formula is used to determine the eigenfrequencies of solar oscillations by fitting both the velocity and intensity power spectra.

  19. Shape coexistence: the shell model view

    NASA Astrophysics Data System (ADS)

    Poves, A.

    2016-02-01

    We shall discuss the meaning of the ‘nuclear shape’ in the laboratory frame proper to the spherical shell model. A brief historical promenade will bring us from Elliott’s SU3 breakthrough to today’s large scale shell model calculations. A section is devoted to the algebraic model which extends drastically the field of applicability of Elliot’s SU3, providing a precious heuristic guidance for the exploration of collectivity in the nuclear chart. Shape coexistence and shape mixing will be shown to occur as the result of the competition between the main actors in the nuclear dynamics; the spherical mean field, and the pairing and quadrupole-quadrupole interactions. These ideas will be illustrated with examples in magic nuclei (40Ca and 68Ni); neutron rich semi-magic (32Mg, and 64Cr); and in proton rich N = Z (72Kr).

  20. Pessimal shapes for packing

    NASA Astrophysics Data System (ADS)

    Kallus, Yoav

    2014-03-01

    The question of which convex shapes leave the most empty space in their densest packing is the subject of Reinhardt's conjecture in two dimensions and Ulam's conjecture in three dimensions. Such conjectures about pessimal packing shapes have proven notoriously difficult to make progress on. I show that the regular heptagon is a local pessimum among all convex shapes, and that the 3D ball is a local pessimum among origin-symmetric shapes. Any shape sufficiently close in the space of shapes to these local pessima can be packed at a greater efficiency than they. In two dimensions and in dimensions above three, the ball is not a local pessimum, so the situation in 3D is unusual and intriguing. I will discuss what conditions conspire to make the 3D ball a local pessimum and whether we can prove that it is also a global pessimum.

  1. Learning Deformable Shape Manifolds

    PubMed Central

    Rivera, Samuel; Martinez, Aleix

    2011-01-01

    We propose an approach to shape detection of highly deformable shapes in images via manifold learning with regression. Our method does not require shape key points be defined at high contrast image regions, nor do we need an initial estimate of the shape. We only require sufficient representative training data and a rough initial estimate of the object position and scale. We demonstrate the method for face shape learning, and provide a comparison to nonlinear Active Appearance Model. Our method is extremely accurate, to nearly pixel precision and is capable of accurately detecting the shape of faces undergoing extreme expression changes. The technique is robust to occlusions such as glasses and gives reasonable results for extremely degraded image resolutions. PMID:22308002

  2. Arrays of coupled chemical oscillators

    PubMed Central

    Forrester, Derek Michael

    2015-01-01

    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 contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning. PMID:26582365

  3. Arrays of coupled chemical oscillators.

    PubMed

    Forrester, Derek Michael

    2015-01-01

    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 contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning. PMID:26582365

  4. Arrays of coupled chemical oscillators

    NASA Astrophysics Data System (ADS)

    Forrester, Derek Michael

    2015-11-01

    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 contrast, situations where the central flames are suppressed are also found. The phenomena leads to in-phase synchronised states emerging between periods of anti-phase synchronisation for arrays with different columnar sizes of candle and positioning.

  5. Synthetic in vitro transcriptional oscillators.

    PubMed

    Kim, Jongmin; Winfree, Erik

    2011-02-01

    The construction of synthetic biochemical circuits from simple components illuminates how complex behaviors can arise in chemistry and builds a foundation for future biological technologies. A simplified analog of genetic regulatory networks, in vitro transcriptional circuits, provides a modular platform for the systematic construction of arbitrary circuits and requires only two essential enzymes, bacteriophage T7 RNA polymerase and Escherichia coli ribonuclease H, to produce and degrade RNA signals. In this study, we design and experimentally demonstrate three transcriptional oscillators in vitro. First, a negative feedback oscillator comprising two switches, regulated by excitatory and inhibitory RNA signals, showed up to five complete cycles. To demonstrate modularity and to explore the design space further, a positive-feedback loop was added that modulates and extends the oscillatory regime. Finally, a three-switch ring oscillator was constructed and analyzed. Mathematical modeling guided the design process, identified experimental conditions likely to yield oscillations, and explained the system's robust response to interference by short degradation products. Synthetic transcriptional oscillators could prove valuable for systematic exploration of biochemical circuit design principles and for controlling nanoscale devices and orchestrating processes within artificial cells. PMID:21283141

  6. Drop oscillation and mass transfer in alternating electric fields. Progress report, May 30, 1991--June 1, 1992

    SciTech Connect

    Carleson, T.E.

    1992-06-24

    In certain cases droplet direct contact heat transfer rates can be significantly enhanced by the application of an alternating electric field. This field can produce shape oscillations in a droplet which will enhance mixing. The theoretical evaluation of the effect of the interaction of the field with drop charge on the hydrodynamics has been completed for small amplitude oscillations. Previous work with a zero order perturbation method was followed up with a first order perturbation method to evaluate the effect of drop distortion on drop charge and field distribution. The first order perturbation results show secondary drop oscillations of four modes and two frequencies in each mode. The most significant secondary oscillation has the same mode and frequency as the second mode oscillation predicted from the first order perturbation work. The resonant frequency of all oscillations decrease with increasing electric field strength and drop charge. Work is currently underway to evaluate the heat transfer enhancement from an applied alternating electric field.

  7. The Shape of Eros

    NASA Technical Reports Server (NTRS)

    2000-01-01

    Looking at a few pictures of Eros under the right lighting conditions gives a reasonable idea of the shape of the asteroid, but analysis of NEAR Shoemaker data requires a very accurate digital model of Eros' shape. This 'shape model' helps the NEAR team analyze images and other types of data. For example, comparing the brightness of imaged regions with the orientation of the corresponding parts of the surface, taken from the shape model, allows scientists to determine whether bright areas are due to just surface orientation or also to surface properties. By 'filling

  8. DISJUNCTIVE NORMAL SHAPE MODELS

    PubMed Central

    Ramesh, Nisha; Mesadi, Fitsum; Cetin, Mujdat; Tasdizen, Tolga

    2016-01-01

    A novel implicit parametric shape model is proposed for segmentation and analysis of medical images. Functions representing the shape of an object can be approximated as a union of N polytopes. Each polytope is obtained by the intersection of M half-spaces. The shape function can be approximated as a disjunction of conjunctions, using the disjunctive normal form. The shape model is initialized using seed points defined by the user. We define a cost function based on the Chan-Vese energy functional. The model is differentiable, hence, gradient based optimization algorithms are used to find the model parameters. PMID:27403233

  9. Shape optimization for DSA

    NASA Astrophysics Data System (ADS)

    Ouaknin, Gaddiel; Laachi, Nabil; Delaney, Kris; Fredrickson, Glenn; Gibou, Frederic

    2016-03-01

    Directed self-assembly using block copolymers for positioning vertical interconnect access in integrated circuits relies on the proper shape of a confined domain in which polymers will self-assemble into the targeted design. Finding that shape, i.e., solving the inverse problem, is currently mainly based on trial and error approaches. We introduce a level-set based algorithm that makes use of a shape optimization strategy coupled with self-consistent field theory to solve the inverse problem in an automated way. It is shown that optimal shapes are found for different targeted topologies with accurate placement and distances between the different components.

  10. An experimental study on resonance of oscillating air/vapor bubbles in water using a two-frequency acoustic apparatus

    NASA Astrophysics Data System (ADS)

    Ohsaka, K.

    2003-05-01

    A two-frequency acoustic apparatus is employed to study the growth behavior of vapor-saturated bubbles driven in a volumetric mode. A unique feature of the apparatus is its capability of trapping a bubble by an ultrasonic standing wave while independently driving it into oscillations by a second lower-frequency acoustic wave. It is observed that the growing vapor bubbles exhibit a periodic shape transition between the volumetric and shape modes due to resonant coupling. In order to explain this observation, we performed an experimental investigation on resonant coupling of air bubbles and obtained the following results: First, the induced shape oscillations are actually a mixed mode that contains the volume component, thus, vapor bubbles can grow while they exhibit shape oscillations. Second, the acoustically levitated bubbles are deformed and therefore, degeneracy in resonant frequency is partially removed. As a result, the vapor bubbles exhibit the shape oscillations in both the axisymmetric mode and asymmetric (three-dimensional) modes. Nonlinear effects in addition to the frequency shift and split due to deformation creates overlapping of the coupling ranges for different modes, which leads to the continuous shape oscillations above a certain bubble radius as the bubble grows.

  11. [Low-Frequency Flow Oscillation

    NASA Technical Reports Server (NTRS)

    Bragg, Michael B.

    1997-01-01

    The results of the research conducted under this grant are presented in detail in three Master theses, by Heinrich, Balow, and Broeren. Additional analysis of the experimental data can be found in two AIAA Journal articles and two conference papers. Citations for all of the studies' publications can be found in the bibliography which is attached. The objective of Heinrich's study was to document the low-frequency flow oscillation on the LRN-1007 airfoil, which had been previously observed at low Reynolds number, to determine its origin, and explore the phenomenon at higher Reynolds number. Heinrich performed detailed flow visualization on the airfoil using surface fluorescent oil and laser-sheet off-body visualization. A large leading-edge separation bubble and trailing-edge separation was identified on the airfoil just prior to the onset of the unsteady stall flow oscillation. From the laser-sheet data, the unsteady flow appeared as a massive boundary-layer separation followed by flow reattachment. Hot-wire data were taken in the wake to identify the presence of the flow oscillation and the dominant frequency. The oscillation was found in the flow from a Reynolds number of 0.3 to 1.3 x 10 exp 6. The Strouhal number based on airfoil projected height was nominally 0.02 and increased slightly with increasing Reynolds number and significantly with increasing airfoil angle of attack. Balow focused his research on the leading-edge separation bubble which was hypothesized to be the origin of the low-frequency oscillation. Initially, experimental measurements in the bubble at the onset of the low-frequency oscillation were attempted to study the characteristics of the bubble and explain possible relationships to the shear-layer-flapping phenomena. Unfortunately, the bubble proved to be extremely sensitive to the probe interference and it drastically reduced the size of the bubble. These detailed measurements were then abandoned by Balow. However, this led to a series of

  12. Oscillations of solar atmosphere neutrinos

    SciTech Connect

    Fogli, G. L.; Lisi, E.; Mirizzi, A.; Montanino, D.; Serpico, P. D.

    2006-11-01

    The Sun is a source of high-energy neutrinos (E(greater-or-similar sign)10 GeV) produced by cosmic ray interactions in the solar atmosphere. We study the impact of three-flavor oscillations (in vacuum and in matter) on solar atmosphere neutrinos, and calculate their observable fluxes at Earth, as well as their event rates in a kilometer-scale detector in water or ice. We find that peculiar three-flavor oscillation effects in matter, which can occur in the energy range probed by solar atmosphere neutrinos, are significantly suppressed by averaging over the production region and over the neutrino and antineutrino components. In particular, we find that the relation between the neutrino fluxes at the Sun and at the Earth can be approximately expressed in terms of phase-averaged vacuum oscillations, dominated by a single mixing parameter (the angle {theta}{sub 23})

  13. Nonstationary oscillations in gyrotrons revisited

    SciTech Connect

    Dumbrajs, O.; Kalis, H.

    2015-05-15

    Development of gyrotrons requires careful understanding of different regimes of gyrotron oscillations. It is known that in the planes of the generalized gyrotron variables: cyclotron resonance mismatch and dimensionless current or cyclotron resonance mismatch and dimensionless interaction length complicated alternating sequences of regions of stationary, periodic, automodulation, and chaotic oscillations exist. In the past, these regions were investigated on the supposition that the transit time of electrons through the interaction space is much shorter than the cavity decay time. This assumption is valid for short and/or high diffraction quality resonators. However, in the case of long and/or low diffraction quality resonators, which are often utilized, this assumption is no longer valid. In such a case, a different mathematical formalism has to be used for studying nonstationary oscillations. One example of such a formalism is described in the present paper.

  14. Magnetically insulated transmission line oscillator

    DOEpatents

    Bacon, L.D.; Ballard, W.P.; Clark, M.C.; Marder, B.M.

    1987-05-19

    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 are 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. 11 figs.

  15. Magnetically insulated transmission line oscillator

    DOEpatents

    Bacon, Larry D.; Ballard, William P.; Clark, M. Collins; Marder, Barry M.

    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.

  16. Dynamics of pinned-contact oscillating gas/liquid lenses

    NASA Astrophysics Data System (ADS)

    Hirsa, Amir; Malouin, Bernard; Olles, Joseph; Lopez, Carlos; Vogel, Michael

    2009-11-01

    Liquid lenses are a natural solution for applications in adaptive optics requiring a fast response. Existing liquid lenses use large disturbances to overcome liquid inertia and subsequently utilize the lens after the oscillations have dampened. An alternate strategy was demonstrated recently: a harmonically-driven liquid lens with an oscillating focal length that allows the capture of any plane in a given range by grabbing the image `in sync' with the oscillations. Hence, by continuously oscillating the lens, the task of changing the focal length is effectively transformed from a mechanical manipulation to the electronic timing of image capture by the sensor, which can be achieved much faster. Good optical quality is possible by designing the liquid lens to traverse states where capillarity produces spherical interfaces. Energy efficiency is achieved through pinned contact lines and operation at resonance. We present experimental results along with predictions for the dynamics of such oscillatory driven lenses, including the effects of liquid volume, driving frequency and amplitude on droplet shapes and resultant optical characteristics. High fidelity imaging was demonstrated at 100 Hz for a millimeter scale liquid lens.

  17. Oscillating behavior of Clostridium difficile Min proteins in Bacillus subtilis.

    PubMed

    Makroczyová, Jana; Jamroškovič, Ján; Krascsenitsová, Eva; Labajová, Nad'a; Barák, Imrich

    2016-06-01

    In rod-shaped bacteria, the proper placement of the division septum at the midcell relies, at least partially, on the proteins of the Min system as an inhibitor of cell division. The main principle of Min system function involves the formation of an inhibitor gradient along the cell axis; however, the establishment of this gradient differs between two well-studied gram-negative and gram-positive bacteria. While in gram-negative Escherichia coli, the Min system undergoes pole-to-pole oscillation, in gram-positive Bacillus subtilis, proper spatial inhibition is achieved by the preferential attraction of the Min proteins to the cell poles. Nevertheless, when E.coli Min proteins are inserted into B.subtilis cells, they still oscillate, which negatively affects asymmetric septation during sporulation in this organism. Interestingly, homologs of both Min systems were found to be present in various combinations in the genomes of anaerobic and endospore-forming Clostridia, including the pathogenic Clostridium difficile. Here, we have investigated the localization and behavior of C.difficile Min protein homologs and showed that MinDE proteins of C.difficile can oscillate when expressed together in B.subtilis cells. We have also investigated the effects of this oscillation on B.subtilis sporulation, and observed decreased sporulation efficiency in strains harboring the MinDE genes. Additionally, we have evaluated the effects of C.difficile Min protein expression on vegetative division in this heterologous host. PMID:26817670

  18. Drops in Space: Super Oscillations and Surfactant Studies

    NASA Technical Reports Server (NTRS)

    Apfel, Robert E.; Tian, Yuren; Jankovsky, Joseph; Shi, Tao; Chen, X.; Holt, R. Glynn; Trinh, Eugene; Croonquist, Arvid; Thornton, Kathyrn C.; Sacco, Albert, Jr.; Coleman, Catherine; Leslie, Fred W.; Matthiesen, David H.

    1996-01-01

    An unprecedented microgravity observation of maximal shape oscillations of a surfactant-bearing water drop the size of a ping pong ball was observed during a mission of Space Shuttle Columbia as part of the second United States Microgravity Laboratory-USML-2 (STS-73, October 20-November 5, 1995). The observation was precipitated by the action of an intense sound field which produced a deforming force on the drop. When this deforming force was suddenly reduced, the drop executed nearly free and axisymmetric oscillations for several cycles, demonstrating a remarkable amplitude of nonlinear motion. Whether arising from the discussion of modes of oscillation of the atomic nucleus, or the explosion of stars, or how rain forms, the complex processes influencing the motion, fission, and coalescence of drops have fascinated scientists for centuries. Therefore, the axisymmetric oscillations of a maximally deformed liquid drop are noteworthy, not only for their scientific value but also for their aesthetic character. Scientists from Yale University, the Jet Propulsion Laboratory (JPL) and Vanderbilt University conducted liquid drop experiments in microgravity using the acoustic positioning/manipulation environment of the Drop Physics Module (DPM). The Yale/JPL group's objectives were to study the rheological properties of liquid drop surfaces on which are adsorbed surfactant molecules, and to infer surface properties such as surface tension, Gibb's elasticity, and surface dilatational viscosity by using a theory which relies on spherical symmetry to solve the momentum and mass transport equations.

  19. Pulsations in the free oscillations of the Earth

    NASA Astrophysics Data System (ADS)

    Sobolev, G. A.

    2015-05-01

    The records from wideband IRIS stations after a strong earthquake are analyzed. A few days after the earthquake, pulsations with a period of 128 min arise and last for about a week. They appear as a periodical variation in the amplitude of the free radial oscillation of the Earth 0S0 having a period of 20.46 min. The period of the pulsations is more than double the period of the lowest-frequency free spheroidal oscillations of the Earth (53.9 min). The pulsations are most pronounced at the mid-latitudinal and equatorial stations and less distinct near the poles. The pulsations are phase synchronous at the nearby stations and antiphase at the stations located in the western and eastern hemispheres. The pulsation amplitude does not depend on the phase of the Earth's tide. The shape and period of the pulsations are fitted by the model of beatings appearing in the Van der Pol oscillator with periodic forcing. The pulsations are hypothesized to result from asynchronous interaction between the free oscillations of the Earth.

  20. High power radial klystron oscillator

    SciTech Connect

    Arman, M.J.

    1995-11-01

    The advantages of the radial klystron amplifier over the conventional klystron amplifier have been reported by Arman et al. Briefly, the radial structure of this design allows for much smaller impedances and thus higher power, the beam-cavity coupling is stronger because the beam travels inside the cavity, and the source is much more compact because there is no need for external magnetic fields. Here the author reports on possible advantages of the radial klystron oscillator over the radial klystron amplifier. The amplifying nature of certain HPM sources is often mandated by the requirement for synchronization and phase-locking of a number of sources in specific applications. In situations where amplification is solely adhered to for the purpose of achieving higher powers, the oscillator will be a better choice if a mechanism can be found to grow the desired mode at the required frequency. By switching to the oscillator mode there will be no need for priming the cavity or maintaining the phase. This simplifies the design and reduces the operational and maintenance cost of the source. Here he reports that an oscillator version of the radial klystron is possible and in fact more suitable for many applications. The mechanism for exciting and growing the mode will be transit-time effects thus providing all the beneficial features of the transit-time oscillators. The complications due to the presence of thin foils in the radial design still persist and will be dealt with in subsequent works. Numerical simulations using the PIC codes MAGIC and SOS indicate the radial klystron oscillator is a viable and efficient means of rf generation.

  1. Regulation of signal transduction by spatial parameters: a case in NF-κB oscillation.

    PubMed

    Ichikawa, Kazuhisa; Ohshima, Daisuke; Sagara, Hiroshi

    2015-04-01

    NF-κB is a transcription factor regulating expression of more than 500 genes, and its dysfunction leads to the autoimmune and inflammatory diseases. In malignant cancer cells, NF-κB is constitutively activated. Thus the elucidation of mechanisms for NF-κB regulation is important for the establishment of therapeutic treatment caused by incorrect NF-κB responses. Cytoplasmic NF-κB translocates to the nucleus by the application of extracellular stimuli such as cytokines. Nuclear NF-κB is known to oscillate with the cycle of 1.5-4.5 h, and it is thought that the oscillation pattern regulates the expression profiles of genes. In this review, first we briefly describe regulation mechanisms of NF-κB. Next, published computational simulations on the oscillation of NF-κB are summarised. There are at least 60 reports on the computational simulation and analysis of NF-κB oscillation. Third, the importance of a 'space' for the regulation of oscillation pattern of NF-κB is discussed, showing altered oscillation pattern by the change in spatial parameters such as diffusion coefficient, nuclear to cytoplasmic volume ratio (N/C ratio), and transport through nuclear membrane. Finally, simulations in a true intracellular space (TiCS), which is an intracellular 3D space reconstructed in a computer with organelles such as nucleus and mitochondria are discussed. PMID:26672147

  2. Smart contact oscillations by IPMCs

    NASA Astrophysics Data System (ADS)

    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.

  3. Cherenkov radiation oscillator without reflectors

    SciTech Connect

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

    2014-05-12

    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. The Effects of Collective Neutrino Oscillations on Supernova Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Seadrow, Shaquann; Frohlich, C.; Duan, H.; Friedland, A.; McLaughlin, G.; Keohane, J. W.

    2014-01-01

    A core-collapse supernova originates from the implosion of the electron degenerate core inside a massive star. Runaway electron capture produces on the order of 1057 neutrinos containing about 1053 erg of energy in total. While the vast majority of neutrinos are eventually released, during the first few seconds these neutrinos drive both the dynamics, and likewise the nucleosynthesis, inside the supernova. Recently, our understanding of oscillations among the different flavors of neutrinos (electron, muon, and tau) has significantly improved, allowing us to ask if neutrino flavor change has a significant effect on nucleosynthesis in a core-collapse supernova. To investigate the effects of collective neutrino flavor oscillations, we use the hydrodynamic conditions from a spherically-symmetrical model of the implosion, bounce, and explosion of the 1.4 solar mass core that is inside an 8.8 solar mass star (Huedepohl et al. 2009). We select 20 mass tracers in the ejecta, varying in initial radii, and follow these trajectories for the first 9 seconds following bounce. We include these trajectories into a nuclear reaction network in order to calculate the detailed nucleosynthesis. We use three sets of neutrino reaction rates, all of which are calculated consistently with the conditions in the supernova model: (i) no collective flavor oscillations, (ii) collective oscillations for normal neutrino mass hierarchy, and (iii) collective oscillations for inverted neutrino mass hierarchy. We calculate the detailed nucleosynthesis for each trajectory for all three sets of neutrino rates. We find that the inclusion of collective oscillations (ii or iii) significantly increases the free neutron abundance; however, we obtain similar results regardless of which hierarchy is used. The increase in free neutrons also increases the subsequent rate of neutron capture, but has only a small effect on the predicted final abundances. This work was performed as part of North Carolina State

  5. Mixed-mode oscillation suppression states in coupled oscillators

    NASA Astrophysics Data System (ADS)

    Ghosh, Debarati; Banerjee, Tanmoy

    2015-11-01

    We report a collective dynamical state, namely the mixed-mode oscillation suppression state where the steady states of the state variables of a system of coupled oscillators show heterogeneous behaviors. We identify two variants of it: The first one is a mixed-mode death (MMD) state, which is an interesting oscillation death state, where a set of variables show dissimilar values, while the rest arrive at a common value. In the second mixed death state, bistable and monostable nontrivial homogeneous steady states appear simultaneously to a different set of variables (we refer to it as the MNAD state). We find these states in the paradigmatic chaotic Lorenz system and Lorenz-like system under generic coupling schemes. We identify that while the reflection symmetry breaking is responsible for the MNAD state, the breaking of both the reflection and translational symmetries result in the MMD state. Using a rigorous bifurcation analysis we establish the occurrence of the MMD and MNAD states, and map their transition routes in parameter space. Moreover, we report experimental observation of the MMD and MNAD states that supports our theoretical results. We believe that this study will broaden our understanding of oscillation suppression states; subsequently, it may have applications in many real physical systems, such as laser and geomagnetic systems, whose mathematical models mimic the Lorenz system.

  6. Rollercoaster Loop Shapes

    ERIC Educational Resources Information Center

    Pendrill, Ann-Marie

    2005-01-01

    Many modern rollercoasters feature loops. Although textbook loops are often circular, real rollercoaster loops are not. In this paper, we look into the mathematical description of various possible loop shapes, as well as their riding properties. We also discuss how a study of loop shapes can be used in physics education.

  7. Rollercoaster loop shapes

    NASA Astrophysics Data System (ADS)

    Pendrill, Ann-Marie

    2005-11-01

    Many modern rollercoasters feature loops. Although textbook loops are often circular, real rollercoaster loops are not. In this paper, we look into the mathematical description of various possible loop shapes, as well as their riding properties. We also discuss how a study of loop shapes can be used in physics education.

  8. Crystal Shape Bingo.

    ERIC Educational Resources Information Center

    Rule, Audrey C.

    This document describes a game that provides students with practice in recognizing three dimensional crystal shapes and planar geometric shapes of crystal faces. It contains information on the objective of the game, game preparation, and rules for playing. Play cards are included (four to a page). (ASK)

  9. Lattice Boltzmann simulations of settling behaviors of irregularly shaped particles

    NASA Astrophysics Data System (ADS)

    Zhang, Pei; Galindo-Torres, S. A.; Tang, Hongwu; Jin, Guangqiu; Scheuermann, A.; Li, Ling

    2016-06-01

    We investigated the settling dynamics of irregularly shaped particles in a still fluid under a wide range of conditions with Reynolds numbers Re varying between 1 and 2000, sphericity ϕ and circularity c both greater than 0.5, and Corey shape factor (CSF) less than 1. To simulate the particle settling process, a modified lattice Boltzmann model combined with a turbulence module was adopted. This model was first validated using experimental data for particles of spherical and cubic shapes. For irregularly shaped particles, two different types of settling behaviors were observed prior to particles reaching a steady state: accelerating and accelerating-decelerating, which could be distinguished by a critical CSF value of approximately 0.7. The settling dynamics were analyzed with a focus on the projected areas and angular velocities of particles. It was found that a minor change in the starting projected area, an indicator of the initial particle orientation, would not strongly affect the settling velocity for low Re. Periodic oscillations developed for all simulated particles when Re>100 . The amplitude of these oscillations increased with Re. However, the periods were not sensitive to Re. The critical Re that defined the transition between the steady and periodically oscillating behaviors depended on the inertia tensor. In particular, the maximum eigenvalue of the inertia tensor played a major role in signaling this transition in comparison to the intermediate and minimum eigenvalues.

  10. Pulse shaping system

    DOEpatents

    Skeldon, M.D.; Letzring, S.A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

  11. Pulse shaping system

    DOEpatents

    Skeldon, Mark D.; Letzring, Samuel A.

    1999-03-23

    Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

  12. Calculations of combustion response profiles and oscillations

    NASA Technical Reports Server (NTRS)

    Priem, Richard J.; Breisacher, Kevin J.

    1993-01-01

    The theory and procedures for determining the characteristics of pressure oscillations in rocket engines with prescribed burning rate oscillations are presented. Pressure and velocity oscillations calculated using this procedure are presented for the Space Shuttle Main Engine (SSME) to show the influence of baffles and absorbers on the burning rate oscillations required to achieve neutral stability. Results of calculations to determine local combustion responses using detailed physical models for injection, atomization, and vaporization with gas phase oscillations in baffled and unbaffled SSME combustors are presented. The contributions of the various physical phenomena occurring in a combustor to oscillations in combustion response were determined.

  13. BLOCKING OSCILLATOR DOUBLE PULSE GENERATOR CIRCUIT

    DOEpatents

    Haase, J.A.

    1961-01-24

    A double-pulse generator, particuiarly a double-pulse generator comprising a blocking oscillator utilizing a feedback circuit to provide means for producing a second pulse within the recovery time of the blocking oscillator, is described. The invention utilized a passive network which permits adjustment of the spacing between the original pulses derived from the blocking oscillator and further utilizes the original pulses to trigger a circuit from which other pulses are initiated. These other pulses are delayed and then applied to the input of the blocking oscillator, with the result that the output from the oscillator circuit contains twice the number of pulses originally initiated by the blocking oscillator itself.

  14. Numerical investigations on a compact magnetic fusion device for studying the effect of external applied magnetic field oscillations on the nuclear burning efficiency of D-T and p-11B fuels

    NASA Astrophysics Data System (ADS)

    Moustaizis, S. D.; Lalousis, P.; Hora, H.; Larour, J.; Auvray, P.; Balcou, P.; Ducret, J.-E.; Martin, P.

    2015-05-01

    The burning process of high density (about 1018cm-3), high temperature (tens to hundreds of keV) plasma trapped by a high mirror-like magnetic field in a Compact Magnetic Fusion (CMF) device is numerically investigated.. The initial high density and high temperature plasma in the CMF device is produced by ultrashort high intensity laser beam interaction with clusters or thin foils, and two fuels, D-T and p-11B are studied. The spatio-temporal evolution of D-T and p-11B plasmas, the production of alphas, the generated electric fields and the high external applied magnetic field are described by a 1-D multifluid code. The initial values for the plasma densities, temperatures and external applied magnetic field (about 100 T) correspond to high β plasmas. The main objectives of the numerical simulations are: to study the plasma trapping, the neutron and alpha production for both fuels, and compare the effect of the external applied magnetic field on the nuclear burning efficiency for the two fuels.. The comparisons and the advantages for each fuel will be presented. The proposed CMF device and the potential operation of the device within the ELI-NP pillar will be discussed.

  15. A flight investigation of oscillating air forces: Equipment and technique

    NASA Technical Reports Server (NTRS)

    Reed, W. H., III

    1975-01-01

    The equipment and techniques are described which are to be used in a project aimed at measuring oscillating air forces and dynamic aeroelastic response of a swept wing airplane at high subsonic speeds. Electro-hydraulic inertia type shakers installed in the wing tips will excite various elastic airplane modes while the related oscillating chordwise pressures at two spanwise wing stations and the wing mode shapes are recorded on magnetic tape. The data reduction technique, following the principle of a wattmeter harmonic analyzer employed by Bratt, Wight, and Tilly, utilizes magnetic tape and high speed electronic multipliers to record directly the real and imaginary components of oscillatory data signals relative to a simple harmonic reference signal. Through an extension of this technique an automatic flight-flutter-test data analyzer is suggested in which vector plots of mechanical admittance or impedance would be plotted during the flight test.

  16. Energy conservation and chaos in the gravitationally driven Fermi oscillator

    NASA Astrophysics Data System (ADS)

    Lopac, V.; Dananić, V.

    1998-10-01

    Chaotic dynamics of the two-body conservative system, which consists of a particle of mass m bouncing elastically on a horizontal plate of mass M supported by an elastic spring, is investigated. The system integrates the properties of coupled oscillators with those of the bouncing-ball and impact oscillator problems. Results obtained by varying the mass ratio M/m and the spring constant k in numerical computations are presented in the form of time-dependent diagrams and discrete maps. The rich variety of resulting chaotic behavior includes strange attractors with fractal structure, resonant islands, crisis, and intermittency route to chaos. The system has a remarkable didactic value as an example of chaotic behavior in simple systems close to everyday experience. The integrable limit M=0 is appropriate for introducing the phase portraits and discussing the interrelationship between the shape of the potential energy curves and the resulting oscillatory motion.

  17. Parametric spatiotemporal oscillation in reaction-diffusion systems

    NASA Astrophysics Data System (ADS)

    Ghosh, Shyamolina; Ray, Deb Shankar

    2016-03-01

    We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions.

  18. Parametric spatiotemporal oscillation in reaction-diffusion systems.

    PubMed

    Ghosh, Shyamolina; Ray, Deb Shankar

    2016-03-01

    We consider a reaction-diffusion system in a homogeneous stable steady state. On perturbation by a time-dependent sinusoidal forcing of a suitable scaling parameter the system exhibits parametric spatiotemporal instability beyond a critical threshold frequency. We have formulated a general scheme to calculate the threshold condition for oscillation and the range of unstable spatial modes lying within a V-shaped region reminiscent of Arnold's tongue. Full numerical simulations show that depending on the specificity of nonlinearity of the models, the instability may result in time-periodic stationary patterns in the form of standing clusters or spatially localized breathing patterns with characteristic wavelengths. Our theoretical analysis of the parametric oscillation in reaction-diffusion system is corroborated by full numerical simulation of two well-known chemical dynamical models: chlorite-iodine-malonic acid and Briggs-Rauscher reactions. PMID:27078346

  19. Classical oscillators in the control of quantum tunneling: Numerical experiments

    NASA Astrophysics Data System (ADS)

    Kar, Susmita; Bhattacharyya, S. P.

    2016-06-01

    The dynamics of a classical anharmonic oscillator is exploited to control the tunneling dynamics of a quantum particle to which the classical oscillator is coupled. The mixed quantum classical problem is investigated at a mean-field like level. The anharmonic strength (λ) , particle mass (Mc) and harmonic stiffness (ωc) of the classical controller are explored as possible control parameters for the tunneling dynamics. The strength, the type of coupling between the quantum system and classical controller and the effective frequency of the controller emerge as crucial factors in shaping the nature and extent of the control. A whole spectrum of possibilities starting from enhancement, suppression to complete destruction of tunneling emerge depending on values assigned to the control parameters, the type of coupling and the control configuration used. When classical controller is replaced by a quantum controller, the control landscape becomes much simpler.

  20. Experiments on self-excited oscillation in a thin-walled collapsible tube

    NASA Astrophysics Data System (ADS)

    Wu, Hai-Jun; Jia, Lai-Bing; Yin, Xie-Zhen

    2015-12-01

    Self-excited oscillation in a collapsible tube is an important phenomenon in physiology. An experimental approach on self-excited oscillation in a thin-walled collapsible tube is developed by using a high transmittance and low Young's modulus silicone rubber tube. The elastic tube is manufactured by the method of centrifugal casting in our laboratory. An optical method for recording the evolution of the cross-sectional areas at a certain position along the longitudinal direction of the tube is developed based on the technology of refractive index matching. With the transparent tube, the tube law is measured under the static no-flow condition. The cross section at the middle position of the tube transfers from a quasi-circular configuration to an ellipse, and then to a dumbell-shape as the chamber pressure is increased. During the self-excited oscillation, two periodic self-excited oscillating states and one transitional oscillating state are identified. They all belong to the LU mode. These different oscillating states are related to the initial cross-sectional shape of the tube caused by the difference of the downstream transmural pressure.

  1. Synchronization and Phase Dynamics of Oscillating Foils

    NASA Astrophysics Data System (ADS)

    Finkel, Cyndee L.

    In this work, a two-dimensional model representing the vortices that animals produce, when they are ying/swimming, was constructed. A D{shaped cylinder and an oscillating airfoil were used to mimic these body{shed and wing{generated vortices, respectively. The parameters chosen are based on the Reynolds numbers similar to that which is observed in nature (˜10 4). In order to imitate the motion of ying/swimming, the entire system was suspended into a water channel from frictionless air{bearings. The position of the apparatus in the channel was regulated with a linear, closed loop PI controller. Thrust/drag forces were measured with strain gauges and particle image velocimetry (PIV) was used to examine the wake structure that develops. The Strouhal number of the oscillating airfoil was compared to the values observed in nature as the system transitions between the accelerated and steady states. The results suggest that self-regulation restricts the values of the Strouhal number to a certain range where no other external sensory input is necessary. As suggested by previous work, this self-regulation is a result of a limit cycle process that stems from nonlinear periodic oscillations. The limit cycles were used to examine the synchronous conditions due to the coupling of the foil and wake vortices. Noise is a factor that can mask details of the synchronization. In order to control its effect, we study the locking conditions using an analytic technique that only considers the phases. Our results show that the phase locking indices are dependent on the Strouhal value as it converges to a frequency locking ratio of ≃0:5. This indicates that synchronization occurs during cruising between the motion of the foil and the measured thrust/drag response of the uid forces. The results suggest that Strouhal number selection in steady forward natural swimming and ying is the result of a limit cycle process and not actively controlled by an organism. An implication of this is

  2. Compressible flow in fluidic oscillators

    NASA Astrophysics Data System (ADS)

    Graff, Emilio; Hirsch, Damian; Gharib, Mory

    2013-11-01

    We present qualitative observations on the internal flow characteristics of fluidic oscillator geometries commonly referred to as sweeping jets in active flow control applications. We also discuss the effect of the geometry on the output jet in conditions from startup to supersonic exit velocity. Supported by the Boeing Company.

  3. Chimera States in Neural Oscillators

    NASA Astrophysics Data System (ADS)

    Bahar, Sonya; Glaze, Tera

    2014-03-01

    Chimera states have recently been explored both theoretically and experimentally, in various coupled nonlinear oscillators, ranging from phase-oscillator models to coupled chemical reactions. In a chimera state, both coherent and incoherent (or synchronized and desynchronized) states occur simultaneously in populations of identical oscillators. We investigate chimera behavior in a population of neural oscillators using the Huber-Braun model, a Hodgkin-Huxley-like model originally developed to characterize the temperature-dependent bursting behavior of mammalian cold receptors. One population of neurons is allowed to synchronize, with each neuron receiving input from all the others in its group (global within-group coupling). Subsequently, a second population of identical neurons is placed under an identical global within-group coupling, and the two populations are also coupled to each other (between-group coupling). For certain values of the coupling constants, the neurons in the two populations exhibit radically different synchronization behavior. We will discuss the range of chimera activity in the model, and discuss its implications for actual neural activity, such as unihemispheric sleep.

  4. High Frequency Stable Oscillate boiling

    NASA Astrophysics Data System (ADS)

    Li, Fenfang; Gonzalez-Avila, Silvestre Roberto; Ohl, Claus Dieter

    2015-11-01

    We present an unexpected regime of resonant bubble oscillations on a thin metal film submerged in water, which is continuously heated with a focused CW laser. The oscillatory bubble dynamics reveals a remarkably stable frequency of several 100 kHz and is resolved from the side using video recordings at 1 million frames per second. The emitted sound is measured simultaneously and shows higher harmonics. Once the laser is switched on the water in contact with the metal layer is superheated and an explosively expanding cavitation bubble is generated. However, after the collapse a microbubble is nucleated from the bubble remains which displays long lasting oscillations. Generally, pinch-off from of the upper part of the microbubble is observed generating a continuous stream of small gas bubbles rising upwards. The cavitation expansion, collapse, and the jetting of gas bubbles are detected by the hydrophone and are correlated to the high speed video. We find the bubble oscillation frequency is dependent on the bubble size and surface tension. A preliminary model based on Marangoni flow and heat transfer can explain the high flow velocities observed, yet the origin of bubble oscillation is currently not well understood.

  5. High-Frequency Gated Oscillator

    NASA Technical Reports Server (NTRS)

    Berard, C. A.

    1982-01-01

    New gated oscillator generates bursts of high-frequency sine waves, square waves, and triangular waves in response to control signals. Each burst starts at zero phase, with tight tolerances on signal amplitude and frequency. Frequencies in megahertz range are made possible by using high-speed comparators and high-speed flip-flop as fast-response threshold detector.

  6. Hydrogen rotation-vibration oscillator

    DOEpatents

    Rhodes, C.K.

    1974-01-29

    A laser system is described wherein molecular species of hydrogen and hydrogen isotopes are induced to oscillate on rotational-vibrational levels by subjecting the hydrogen to a transverse beam of electrons of a narrowly defined energy between about 1 and 5 eV, thereby producing high intensity and high energy output. (Official Gazette)

  7. Oscillator Stengths and Their Uncertainties

    NASA Astrophysics Data System (ADS)

    Wahlgren, G. M.

    2010-11-01

    The oscillator strength is a key parameter in the description of the line absorption coefficient. It can be determined through experiment, abinitio and semi-empirical calculations, and backward analysis of line profiles. Each method has its advantages, and the uncertainty attached to its determination can range from low to indeterminable. For analysis of line profiles or equivalent widths the uncertainty in the oscillator strength can rival or surpass the difference between the derived element abundance from classical LTE and non-LTE analyses. It is therefore important to understand the nature of oscillator strength uncertainties and to assess whether this uncertainty can be a factor in choosing to initiate a non-LTE analysis or in the interpretation of its results. Methods for the determination of the oscillator strength are presented, prioritizing experiments, along with commentary about the sources and impact of the uncertainties. The Sei spectrum is used to illustrate how gf-values can be constructed from published data on atomic lifetimes and line intensities.

  8. [Forced Oscillations of DNA Bases].

    PubMed

    Yakushevich, L V; Krasnobaeva, L A

    2016-01-01

    This paper presents the results of the studying of forced angular oscillations of the DNA bases with the help of the mathematical model consisting of two coupled nonlinear differential equations that take into account the effects of dissipation and the influence of an external periodic field. The calculation results are illustrated for sequence of gene encoding interferon alpha 17 (IFNA 17). PMID:27192830

  9. Constant-amplitude RC oscillator

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Westbrook, R. M.

    1970-01-01

    Sinusoidal oscillator has a frequency determined by resistance-capacitance /RC/ values of two charge control devices and a constant-amplitude voltage independent of frequency and RC values. RC elements provide either voltage-control, resistance-control, or capacitance-control of the frequency.

  10. Cubication of Conservative Nonlinear Oscillators

    ERIC Educational Resources Information Center

    Belendez, Augusto; Alvarez, Mariela L.; Fernandez, Elena; Pascual, Immaculada

    2009-01-01

    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…

  11. Theory of quantum oscillations in self-broadening of 4{sup 2}S-n{sup 2}S Rydberg transitions in potassium

    SciTech Connect

    Herman, R. M.; Henry, M. E.

    1997-01-05

    A pseudohamiltonian impact theory for describing Rydberg transition line shapes is proposed. Preliminary results give lineshapes in reasonable agreement with experiment, including the quantum oscillations in alkali self broadening and shifting, and rare gas broadening.

  12. Nonlinear Spectroscopic Theory of Displaced Harmonic Oscillators with Differing Curvatures: A Correlation Function Approach

    NASA Astrophysics Data System (ADS)

    Fidler, Andrew F.; Engel, Gregory S.

    2013-10-01

    We present a theory for a bath model in which we approximate the adiabatic nuclear potential surfaces on the ground and excited electronic states by displaced harmonic oscillators that differ in curvature. Calculations of the linear and third-order optical response functions employ an effective short-time approximation coupled with the cumulant expansion. In general, all orders of correlation contribute to the optical response, indicating that the solvation process cannot be described as Gaussian within the model. Calculations of the linear absorption and fluorescence spectra resulting from the theory reveal a stronger temperature dependence of the Stokes shift along with a general asymmetry between absorption and fluorescence line shapes, resulting purely from the difference in the phonon side band. We discuss strategies for controlling spectral tuning and energy-transfer dynamics through the manipulation of the excited-state and ground-state curvature. Calculations of the nonlinear response also provide insights into the dynamics of the system-bath interactions and reveal that multidimensional spectroscopies are sensitive to a difference in curvature between the ground- and excited-state adiabatic surfaces. This extension allows for the elucidation of short-time dynamics of dephasing that are accessible in nonlinear spectroscopic methods.

  13. The exchangeability of shape

    PubMed Central

    2010-01-01

    Background Landmark based geometric morphometrics (GM) allows the quantitative comparison of organismal shapes. When applied to systematics, it is able to score shape changes which often are undetectable by traditional morphological studies and even by classical morphometric approaches. It has thus become a fast and low cost candidate to identify cryptic species. Due to inherent mathematical properties, shape variables derived from one set of coordinates cannot be compared with shape variables derived from another set. Raw coordinates which produce these shape variables could be used for data exchange, however they contain measurement error. The latter may represent a significant obstacle when the objective is to distinguish very similar species. Results We show here that a single user derived dataset produces much less classification error than a multiple one. The question then becomes how to circumvent the lack of exchangeability of shape variables while preserving a single user dataset. A solution to this question could lead to the creation of a relatively fast and inexpensive systematic tool adapted for the recognition of cryptic species. Conclusions To preserve both exchangeability of shape and a single user derived dataset, our suggestion is to create a free access bank of reference images from which one can produce raw coordinates and use them for comparison with external specimens. Thus, we propose an alternative geometric descriptive system that separates 2-D data gathering and analyzes. PMID:20964872

  14. Entrained neural oscillations in multiple frequency bands comodulate behavior

    PubMed Central

    Henry, Molly J.; Herrmann, Björn

    2014-01-01

    Our sensory environment is teeming with complex rhythmic structure, to which neural oscillations can become synchronized. Neural synchronization to environmental rhythms (entrainment) is hypothesized to shape human perception, as rhythmic structure acts to temporally organize cortical excitability. In the current human electroencephalography study, we investigated how behavior is influenced by neural oscillatory dynamics when the rhythmic fluctuations in the sensory environment take on a naturalistic degree of complexity. Listeners detected near-threshold gaps in auditory stimuli that were simultaneously modulated in frequency (frequency modulation, 3.1 Hz) and amplitude (amplitude modulation, 5.075 Hz); modulation rates and types were chosen to mimic the complex rhythmic structure of natural speech. Neural oscillations were entrained by both the frequency modulation and amplitude modulation in the stimulation. Critically, listeners’ target-detection accuracy depended on the specific phase–phase relationship between entrained neural oscillations in both the 3.1-Hz and 5.075-Hz frequency bands, with the best performance occurring when the respective troughs in both neural oscillations coincided. Neural-phase effects were specific to the frequency bands entrained by the rhythmic stimulation. Moreover, the degree of behavioral comodulation by neural phase in both frequency bands exceeded the degree of behavioral modulation by either frequency band alone. Our results elucidate how fluctuating excitability, within and across multiple entrained frequency bands, shapes the effective neural processing of environmental stimuli. More generally, the frequency-specific nature of behavioral comodulation effects suggests that environmental rhythms act to reduce the complexity of high-dimensional neural states. PMID:25267634

  15. Recent Simulation Conclusions for Damped-Oscillation Control

    SciTech Connect

    Kress, R.L.

    2001-02-19

    When suspended payloads are moved with an overhead crane, pendulum like oscillations are naturally introduced. This presents a problem any time a crane is used, especially when expensive and/or delicate objects are moved, when moving in a cluttered and/or hazardous environment, and when objects are to be placed in tight locations. For example, one nuclear waste-handling operation examined by the U.S. Department of Energy (DOE) Oak Ridge National Laboratory (ORNL) is the transportation of heavy objects such as waste storage casks or barrels from one location to another through cluttered process facility environments or storage facilities. Typically, an object is lifted by a crane hook on the end of a cable, creating a pendulum that is free to swing during transit. This swinging motion makes remote positioning of casks or barrels difficult to control precisely and is potentially destructive to facility equipment and to other storage containers. Typically, a crane operator moves objects slowly to minimize induced swinging and allow time for oscillations to dampen, maintaining safety but greatly decreasing the efficiency of operations. Using damped-oscillation control algorithms is one approach to solving this problem. This paper summarizes recent simulation results in damped-oscillation-type control algorithms. It also discusses practical implementation issues including control algorithm robustness to payload length changes, hardware requirements for implementation of the control algorithms, and system limits on Coulomb friction.

  16. The Shapes of Physics

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2013-12-01

    I have used many ploys to start a course in introductory physics, but one of the more interesting ones was to spend 20 minutes describing some of the curves and shapes that we would encounter in our year together. The students saw parabolas, catenaries, hyperbolas, cycloids, circles, ellipses, and helices, and were shown examples, either live or on slides, of these shapes. The world of physics is three-dimensional, and students need to see what curves and trajectories span it. Once they see these shapes in nature, they look at the world around them in fresh ways.

  17. Shaping light with MOEMS

    NASA Astrophysics Data System (ADS)

    Noell, W.; Weber, S.; Masson, J.; Extermann, J.; Bonacina, L.; Bich, A.; Bitterli, R.; Herzig, H. P.; Kiselev, D.; Scharf, T.; Voelkel, R.; Weible, K. J.; Wolf, J.-P.; de Rooij, N. F.

    2011-03-01

    Shaping light with microtechnology components has been possible for many years. The Texas Instruments digital micromirror device (DMD) and all types of adaptive optics systems are very sophisticated tools, well established and widely used. Here we present, however, two very dedicated systems, where one is an extremely simple MEMS-based tunable diffuser, while the second device is complex micromirror array with new capabilities for femtosecond laser pulse shaping. Showing the two systems right next to each other demonstrates the vast options and versatility of MOEMS for shaping light in the space and time domain.

  18. Shape memory polymer foams

    NASA Astrophysics Data System (ADS)

    Santo, Loredana

    2016-02-01

    Recent advances in shape memory polymer (SMP) foam research are reviewed. The SMPs belong to a new class of smart polymers which can have interesting applications in microelectromechanical systems, actuators and biomedical devices. They can respond to specific external stimulus changing their configuration and then remember the original shape. In the form of foams, the shape memory behaviour can be enhanced because they generally have higher compressibility. Considering also the low weight, and recovery force, the SMP foams are expected to have great potential applications primarily in aerospace. This review highlights the recent progress in characterization, evaluation, and proposed applications of SMP foams mainly for aerospace applications.

  19. A theory of generalized Bloch oscillations.

    PubMed

    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. PMID:26986189

  20. Opto-Electronic Oscillator and its Applications

    NASA Technical Reports Server (NTRS)

    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.

  1. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

  2. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, R.P.

    1992-11-24

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

  3. Effect of oscillation-mark formation on the surface quality of continuously cast steel slabs

    NASA Astrophysics Data System (ADS)

    Takeuchi, E.; Brimacombe, J. K.

    1985-09-01

    In a study of early solidification during the continuous casting of steel slabs, the effect of the formation of oscillation marks on the surface quality of the slabs has been examined by metallographic in-vestigation of slab samples and by performing a set of mathematical analyses. Positive segregation of solute elements, especially phosphorus and manganese, has been observed at the bottom of the oscillation marks and has been classified into two categories. One type is observed at the end of the overflow region on subsurface hooks which originate from partial solidification of the meniscus. A heat-flow model which takes into account the shape of the oscillation marks has revealed that this type of positive segregation is caused by local delay of solidification at the bottom of the oscillation marks. The other type of positive segregation has been found in a layer on the bottom of the oscillation marks without subsurface hooks. This form of segregation cannot be explained by the heat-flow model, but is likely due to a penetration mechanism in which the negative pressure in the flux channel generated during the upward motion of the mold draws out interdendritic liquid from the semi-solidified shell. Transverse cracks are found along the bottom of oscillation marks. The surface of the transverse cracks exhibits an interdendritic appearance in the vicinity of the slab surface, which implies that the cracks are initiated as hot tears in the mold region. A heat-flow analysis predicts that deep oscillation marks cause nonuniformity of the shell in the mold, which also was observed in the metallographic in-vestigation. According to the heat-flow analysis, not only the depth but also the pitch of the oscillation marks affects the shell profile. Therefore increasing the frequency of mold oscillation effectively reduces transverse cracks, by decreasing both the depth and the pitch of oscillation marks.

  4. Shape coexistence and triaxiality in the superheavy nuclei.

    PubMed

    Cwiok, S; Heenen, P-H; Nazarewicz, W

    2005-02-17

    Superheavy nuclei represent the limit of nuclear mass and charge; they inhabit the remote corner of the nuclear landscape, whose extent is unknown. The discovery of new elements with atomic numbers Z > or = 110 has brought much excitement to the atomic and nuclear physics communities. The existence of such heavy nuclei hangs on a subtle balance between the attractive nuclear force and the disruptive Coulomb repulsion between protons that favours fission. Here we model the interplay between these forces using self-consistent energy density functional theory; our approach accounts for spontaneous breaking of spherical symmetry through the nuclear Jahn-Teller effect. We predict that the long-lived superheavy elements can exist in a variety of shapes, including spherical, axial and triaxial configurations. In some cases, we anticipate the existence of metastable states and shape isomers that can affect decay properties and hence nuclear half-lives. PMID:15716943

  5. Synchronization of Micromechanical Oscillators Using Light

    NASA Astrophysics Data System (ADS)

    Zhang, Mian; Wiederhecker, Gustavo S.; Manipatruni, Sasikanth; Barnard, Arthur; McEuen, Paul; Lipson, Michal

    2012-12-01

    Synchronization, the emergence of spontaneous order in coupled systems, is of fundamental importance in both physical and biological systems. We demonstrate the synchronization of two dissimilar silicon nitride micromechanical oscillators, that are spaced apart by a few hundred nanometers and are coupled through an optical cavity radiation field. The tunability of the optical coupling between the oscillators enables one to externally control the dynamics and switch between coupled and individual oscillation states. These results pave a path toward reconfigurable synchronized oscillator networks.

  6. Patterns of cell thickness oscillations during directional migration of Physarum polycephalum.

    PubMed

    Rodiek, Beatrice; Takagi, Seiji; Ueda, Tetsuo; Hauser, Marcus J B

    2015-07-01

    The functional relationship between the velocity of cell locomotion and intracellular spatial patterns of thickness oscillations in the acellular slime mould Physarum polycephalum was studied. The freely migrating plasmodial cells of 300-800 µm length were tadpole-shaped and displayed thickness oscillations along their longitudinal (body) axis. Two distinct patterns of intracellular thickness oscillations were observed in dependence on the locomotive velocity. The first mode consisted of a single travelling wave that propagated from the rear to the front of the cell. This pattern occurred when the plasmodium migrated slowly. The second mode was a multinodal standing wave that was found during events of fast propagation. Transitions between these two types of cell thickness oscillation patterns took place in narrow propagation velocity intervals. We discuss the possible mechanism leading to these patterns, which are conjectured to modulate both the intracellular pressure and the velocity of free locomotion of the cell. PMID:25921614

  7. Oscillation of bundle conductors in overhead lines due to turbulent wind

    SciTech Connect

    Diana, G.; Cheli, F. ); Manenti, A. ); Nicolini, P.; Tavano, F. )

    1990-10-01

    Due to the wind, the bundle conductors in overhead lines can oscillate and the distance between the phases can be reduced. This kind of movement may be caused by: non expansive oscillations of the phases due to the wind turbulence and to the correlated variations of the bundles aerodynamic coefficients during the movement (buffeting); expansive oscillations, or galloping, of the phases due to the unstable aerodynamic shapes that bundles may assume in presence of ice. This paper presents an analytical methodology to examine the dynamic behaviour of bundles subjected to the above mentioned phenomena. The results obtained during experiments carried out on a span of an energized 420-kV line equipped with triple bundles and subjected to oscillations due to buffeting are exposed. Lastly, the experimental data are compared with the analytical results.

  8. Morphological effect of oscillating magnetic nanoparticles in killing tumor cells

    NASA Astrophysics Data System (ADS)

    Cheng, Dengfeng; Li, Xiao; Zhang, Guoxin; Shi, Hongcheng

    2014-04-01

    Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 μg/mL rod-shaped MNPs (rMNP, length of 200 ± 50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200 ± 50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 μg/mL) or lower (20 μg/mL) concentration of MNPs was less efficient than that achieved at 100 μg/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations.

  9. Reversible Shape Memory

    NASA Astrophysics Data System (ADS)

    Zhou, Jing; Li, Qiaoxi; Turner, Sara; Brosnan, Sarah; Tippets, Cary; Carrillo, Jan-Michael; Nykypnachuk, Dmytro; Gang, Oleg; Dobrynin, Andrey; Lopez, Rene; Ashby, Valerie; Sheiko, Sergei

    2014-03-01

    Reversible shape memory has been achieved on various shapes, e.g. hairpin, origami, coil, robotic gripper and flow rate control device, allowing for multiple switching between encoded shapes without applying any external force. Also, the reversible photonic structure molded in dielectric elastomers has been designed. Maximum reversibility can be achieved by tuning the crosslinking density and the degree of crystallinity of semi-crystalline elastomers. Different crystallization protocols including isothermal and cooling crystallization have been applied to develop a universal picture integrating different shape memory (SM) behaviors: conventional one-way SM, two-way reversible SM, and one-way reversible SM. Acknowledge financial support from the NSF DMR-1122483, DMR- 1004576, and DMR-1206957.

  10. Fluidic Oscillator Array for Synchronized Oscillating Jet Generation

    NASA Technical Reports Server (NTRS)

    Koklu, Mehti (Inventor)

    2016-01-01

    A fluidic oscillator array includes a plurality of fluidic-oscillator main flow channels. Each main flow channel has an inlet and an outlet. Each main flow channel has first and second control ports disposed at opposing sides thereof, and has a first and a second feedback ports disposed at opposing sides thereof. The feedback ports are located downstream of the control ports with respect to a direction of a fluid flow through the main flow channel. The system also includes a first fluid accumulator in fluid communication with each first control port and each first feedback port, and a second fluid accumulator in fluid communication with each second control port and each second feedback port.

  11. Shape memory polyurethane nanocomposites

    NASA Astrophysics Data System (ADS)

    Cao, Feina

    Shape memory polymers are smart materials which can remember their original shapes. However, the low recovery stress and low mechanical strength limit the commercial applications of shape memory polymers. In this study, nanoclays were introduced to shape memory polyurethanes (SMPU) to augment these properties by enhance the network of SMPU. Several factors which influence the shape recovery stress were evaluated, including the nature of polymer chain by using different monomers, type of clay particles, extent of filler dispersion, clay content and deformation conditions. It was found that only reactive clay particles were well dispersed into polyurethane matrix by the tethering between --CH2CH 2OH functional groups in clay surfactants and polyurethane chains. Two different shape memory polyurethanes (Systems I & II) prepared by bulk polymerization were compared. The shape memory effect of System I was triggered by melting of the soft segment crystals, while that of System II was by glass transition of the soft segments. It was seen that the reactive clay particles dispersed well in both polyurethane matrices and augmented the recovery stress, e.g., 20% increase with 1 wt % nanoclay in System I and 40% increase with 5 wt % nanoclay in System II were observed. In System I, clay particles interfered with soft segment crystallization, and promoted phase mixing between the hard and soft segments, thus affecting the fixity and recovery ratio. Nevertheless, the soft segment crystallinity was still enough and in some cases increased due to stretching to exhibit excellent shape fixity and shape recovery ratio. The higher loading of clay particles accelerated the stress relaxation, resulting in reduction of recovery stress. In System II, no significant effect of clay particles in phase separation was observed, so there was no influence of clay on shape fixity and recovery ratio. The recovery stress increased with reactive nanoclay content. It was also found that the recovery

  12. The SD oscillator and its attractors

    NASA Astrophysics Data System (ADS)

    Cao, Q.; Wiercigroch, M.; Pavlovskaia, E.; Grebogi, C.; Michael, J.; Thompson, T.

    2008-02-01

    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.

  13. Mechanical and current oscillations in corroding electrodes

    SciTech Connect

    Teschke, O.; Galembeck, F.; Tenan, M.A.

    1985-06-01

    Mechanical oscillations of the solution meniscus risen around a corroding wire electrode were observed in synchronism with electrical current oscillations. Scanning electron microscopy coupled to microprobe analysis was used to investigate the topochemistry of the system under study. Solution capillarity effects on iron and on iron compounds are related to the oscillations detected in this system.

  14. NOx Emission Reduction by Oscillating Combustion

    SciTech Connect

    2005-09-01

    This project focuses on a new technology that reduces NOx emissions while increasing furnace efficiency for both air- and oxygen-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace.

  15. Quantum phases for a generalized harmonic oscillator

    NASA Astrophysics Data System (ADS)

    Bracken, Paul

    2008-03-01

    An effective Hamiltonian for the generalized harmonic oscillator is determined by using squeezed state wavefunctions. The equations of motion over an extended phase space are determined and then solved perturbatively for a specific choice of the oscillator parameters. These results are used to calculate the dynamic and geometric phases for the generalized oscillator with this choice of parameters.

  16. Squeezed states of damped oscillator chain

    NASA Technical Reports Server (NTRS)

    Manko, O. V.

    1993-01-01

    The Caldirola-Kanai model of one-dimensional damped oscillator is extended to the chain of coupled parametric oscillators with damping. The correlated and squeezed states for the chain of coupled parametric oscillators with damping are constructed. Based on the concept of the integrals of motion, it is demonstrated how squeezing phenomenon arises due to parametric excitation.

  17. Studies of the shapes of heavy pear-shaped nuclei at ISOLDE

    NASA Astrophysics Data System (ADS)

    Butler, P. A.

    2016-07-01

    For certain combinations of protons and neutrons there is a theoretical expectation that the shape of nuclei can assume octupole deformation, which would give rise to reflection asymmetry or a "pear-shape" in the intrinsic frame, either dynamically (octupole vibrations) or statically (permanent octupole deformation). I will briefly review the historic evidence for reflection asymmetry in nuclei and describe how recent experiments carried out at REX-ISOLDE have constrained nuclear theory and how they contribute to tests of extensions of the Standard Model. I will also discuss future prospects for measuring nuclear shapes from Coulomb Excitation: experiments are being planned that will exploit beams from HIE-ISOLDE that are cooled in the TSR storage ring and injected into a solenoidal spectrometer similar to the HELIOS device developed at the Argonne National Laboratory.

  18. Optimization of Pulse Shape Discrimination of PROSPECT Liquid Scintillator Signals

    NASA Astrophysics Data System (ADS)

    Han, Ke; Prospect Collaboration

    2015-04-01

    PROSPECT, A Precision Oscillation and Spectrum Experiment, will use a segmented Li-6 doped liquid scintillator detector for precision measurement of the reactor anti-neutrino spectrum at the High Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT also searches for very short baseline neutrino oscillation, an indication of the existence of eV-scale sterile neutrinos. Pulse shape analysis of the prompt anti-neutino signal and delayed neutron capture on Li-6 signal will greatly suppress background sources such as fast neutrons and accidental coincidence of gammas. In this talk, I will discuss different pulse shape parameters used in PROSPECT prototype detectors and multivariate optimization of event selection cuts based on those parameters.

  19. Universality of fragment shapes.

    PubMed

    Domokos, Gábor; Kun, Ferenc; Sipos, András Árpád; Szabó, Tímea

    2015-01-01

    The shape of fragments generated by the breakup of solids is central to a wide variety of problems ranging from the geomorphic evolution of boulders to the accumulation of space debris orbiting Earth. Although the statistics of the mass of fragments has been found to show a universal scaling behavior, the comprehensive characterization of fragment shapes still remained a fundamental challenge. We performed a thorough experimental study of the problem fragmenting various types of materials by slowly proceeding weathering and by rapid breakup due to explosion and hammering. We demonstrate that the shape of fragments obeys an astonishing universality having the same generic evolution with the fragment size irrespective of materials details and loading conditions. There exists a cutoff size below which fragments have an isotropic shape, however, as the size increases an exponential convergence is obtained to a unique elongated form. We show that a discrete stochastic model of fragmentation reproduces both the size and shape of fragments tuning only a single parameter which strengthens the general validity of the scaling laws. The dependence of the probability of the crack plan orientation on the linear extension of fragments proved to be essential for the shape selection mechanism. PMID:25772300

  20. On Characterizing Particle Shape

    NASA Technical Reports Server (NTRS)

    Ennis, Bryan J.; Rickman, Douglas; Rollins, A. Brent; Ennis, Brandon

    2014-01-01

    It is well known that particle shape affects flow characteristics of granular materials, as well as a variety of other solids processing issues such as compaction, rheology, filtration and other two-phase flow problems. The impact of shape crosses many diverse and commercially important applications, including pharmaceuticals, civil engineering, metallurgy, health, and food processing. Two applications studied here include the dry solids flow of lunar simulants (e.g. JSC-1, NU-LHT-2M, OB-1), and the flow properties of wet concrete, including final compressive strength. A multi-dimensional generalized, engineering method to quantitatively characterize particle shapes has been developed, applicable to both single particle orientation and multi-particle assemblies. The two-dimension, three dimension inversion problem is also treated, and the application of these methods to DEM model particles will be discussed. In the case of lunar simulants, flow properties of six lunar simulants have been measured, and the impact of particle shape on flowability - as characterized by the shape method developed here -- is discussed, especially in the context of three simulants of similar size range. In the context of concrete processing, concrete construction is a major contributor to greenhouse gas production, of which the major contributor is cement binding loading. Any optimization in concrete rheology and packing that can reduce cement loading and improve strength loading can also reduce currently required construction safety factors. The characterization approach here is also demonstrated for the impact of rock aggregate shape on concrete slump rheology and dry compressive strength.