Automatic visual inspection of hybrid microcircuits
Energy Technology Data Exchange (ETDEWEB)
Hines, R.E.
1980-05-01
An automatic visual inspection system using a minicomputer and a video digitizer was developed for inspecting hybrid microcircuits (HMC) and thin-film networks (TFN). The system performed well in detecting missing components on HMCs and reduced the testing time for each HMC by 75%.
Hybrid microcircuit via development. Final report
Energy Technology Data Exchange (ETDEWEB)
Norwood, D.P.
1980-06-01
Manufacturing processes were developed for making holes in alumina substrates, metallizing substrates on both sides and through the holes (vias), dry film photolithographing 6-..mu..m-thick gold to 127-..mu..m line widths and spacings, determining via quality, and protecting vias during HMC assembly processes. The few problems encountered were solved, and via technology is now established as a reliable and repeatable production technology for hybrid microcircuits. Via resistance on product HMCs usually measures from 4 to 6 m..cap omega.. which is well below the 10 m..cap omega.. maximum limit.
Feasibilty of electroplated gold for hybrid microcircuits
Energy Technology Data Exchange (ETDEWEB)
Blessner, P.L.
1978-01-01
Electroplating was investigated as a method of providing thick gold films. Because electroplated gold has never been used for hybrid microcircuit (HMC) substrate metallization, this feasibility study was also designed to determine the characteristics of electroplated gold and its compatibility with present HMC fabrication processes. Ceramic substrates 95 by 114 mm (3.75 by 4.5 in.) were electroplated with 6, 10, and 25 ..mu..m of gold after 0.02 ..mu..m of chromium and 0.5 ..mu..m of gold had been either sputtered or vacuum evaporated onto the substrate surfaces. Substrates vacuum evaporated with 6 ..mu..m of gold were used as a control group. The substrates were evaluated for via resistance, RF electrical characteristics, conductor definition and resolution, solder wettability, thermocompression bondability, and environmental stability.
Comparison of metallization systems for thin film hybrid microcircuits
Energy Technology Data Exchange (ETDEWEB)
Hines, R.A.; Raut, M.K.
1980-08-01
Five metallization systems were evaluated for fabricating thin film hybrid microcircuits. The titanium/palladium/electroplated gold system proved superior in terms of thermocompression bondability, corrosion resistance, and solderability.
Design and quality standards for custom hybrid microcircuits
Allen, R. V.
1977-01-01
A hybrid microcircuit standard was developed after a thorough review of applicable NASA, military, industry, and technical society specifications and standards and compilation of comments from technical reviewers throughout the hybrid industry. The draft of the standard submitted to the technical reviewers, the comments from the reviewers, and the completed standard are discussed.
Hybrid microcircuit technology handbook materials, processes, design, testing and production
Licari, James J
1998-01-01
The Hybrid Microcircuit Technology Handbook integrates the many diverse technologies used in the design, fabrication, assembly, and testing of hybrid segments crucial to the success of producing reliable circuits in high yields. Among these are: resistor trimming, wire bonding, die attachment, cleaning, hermetic sealing, and moisture analysis. In addition to thin films, thick films, and assembly processes, important chapters on substrate selections, handling (including electrostatic discharge), failure analysis, and documentation are included. A comprehensive chapter of design guidelines will
Robinson, E. A.
1973-01-01
Quality, reliability, and design standards for microwave hybrid microcircuits were established. The MSFC Standard 85M03926 for hybrid microcircuits was reviewed and modifications were generated for use with microwave hybrid microcircuits. The results for reliability tests of microwave thin film capacitors, transistors, and microwave circuits are presented. Twenty-two microwave receivers were tested for 13,500 unit hours. The result of 111,121 module burn-in and operating hours for an integrated solid state transceiver module is reported.
Proceedings of the 1980 ERADCOM Hybrid Microcircuit Symposium, 1980, Fort Monmouth, New Jersey,
1980-06-01
identify in lokmabr Papers discuss apitonof hyri microcircuits ingovernment communication, hybrid microcircuits, past and future were described along...Cos Aseml ,Bn Appoasdchi Facilit C(Minos used Cograms)o Figure Wir. 7ORAM Hyri Cirui Sce2i TalBonomdionoiBnignproce CoonAsemlynon MapenuoWired 4-20K
Development of lead-free solders for hybrid microcircuits
Energy Technology Data Exchange (ETDEWEB)
Hosking, F.M.; Vianco, P.T.; Frear, D.R.; Robinson, D.G.
1996-01-01
Extensive work has been conducted by industry to develop lead-free solders for electronics applications. The driving force behind this effort is pressure to ban or tax the use of lead-bearing solders. There has been further interest to reduce the use of hazardous chemical cleaners. Lead-free soldering and low-residue, ``no clean`` assembly processing are being considered as solutions to these environmental issues. Most of the work has been directed toward commercial and military printed wiring board (PWB) technology, although similar problems confront the hybrid microcircuit (HMC) industry, where the development of lead-free HMC solders is generally lagging. Sandia National Laboratories is responsible for designing a variety of critical, high reliability hybrid components for radars. Sandia has consequently initiated a project, as part of its Environmentally Conscious Manufacturing program, to develop low-residue, lead-free soldering for HMCs. This paper discusses the progress of that work.
Hybrid microcircuit board assembly with lead-free solders
Energy Technology Data Exchange (ETDEWEB)
Vianco, P.T.; Hernandez, C.L.; Rejent, J.A.
2000-01-11
An assessment was made of the manufacturability of hybrid microcircuit test vehicles assembled using three Pb-free solder compositions 96.5Sn--3.5Ag (wt.%), 91.84Sn--3.33Ag--4.83Bi, and 86.85Sn--3.15Ag--5.0Bi--5.0Au. The test vehicle substrate was 96% alumina; the thick film conductor composition was 76Au--21Pt--3Pd. Excellent registration between the LCCC or chip capacitor packages and the thick film solder pads was observed. Reduced wetting of bare (Au-coated) LCCC castellations was eliminated by hot solder dipping the I/Os prior to assembly of the circuit card. The Pb-free solders were slightly more susceptible to void formation, but not to a degree that would significantly impact joint functionality. Microstructural damage, while noted in the Sn-Pb solder joints, was not observed in the Pb-free interconnects.
Design guidelines for use of adhesives and organic coatings in hybrid microcircuits
Caruso, S. V.; Licari, J. J.; Perkins, K. L.; Schramm, W. A.
1974-01-01
A study was conducted to investigate the reliability of organic adhesives in hybrid microcircuits. The objectives were twofold: (1) to identify and investigate problem areas that could result from the use of organic adhesives and (2) to develop evaluation tests to quantify the extent to which these problems occur for commercially available adhesives. Efforts were focused on electrically conductive adhesives. Also, a study was made to evaluate selected organic coatings for contamination protection for hybrid microcircuits.
Proceedings of the ECOM Hybrid Microcircuit Symposium, 1976
1976-06-01
For Low Cost Avionics W. W. Staley , Westinghouse Electric Corporation 372 SDI Modules J. Fishel, Circuit Technology Inc. 385 Hybrid Thick Film...or Gerber plotters. i Drawings, when required, are usually generated from the circuit layout. They may be used as assembly aids or inspection guides...TCVCXO-I (left) and TCVCXO-II. <A <•SA 4 . .4’.374 SEM/HYBRIDS, PARTN1.RS FOR LOW COST AVIONICS W. W. Staley Systems Development Division
Development of low cost custom hybrid microcircuit technology
Perkins, K. L.; Licari, J. J.
1981-01-01
Selected potentially low cost, alternate packaging and interconnection techniques were developed and implemented in the manufacture of specific NASA/MSFC hardware, and the actual cost savings achieved by their use. The hardware chosen as the test bed for this evaluation ws the hybrids and modules manufactured by Rockwell International fo the MSFC Flight Accelerometer Safety Cut-Off System (FASCOS). Three potentially low cost packaging and interconnection alternates were selected for evaluation. This study was performed in three phases: hardware fabrication and testing, cost comparison, and reliability evaluation.
Caruso, S. V.; Perkins, K. L.; Licari, J. J.
1973-01-01
Although it is generally accepted that the use of adhesives in the assembly of hybrid microcircuits offers advantages over other bonding methods, there currently does not exist a set of guidelines for the selection of adhesives which will insure that hybrid microcircuits assembled with them will meet the long use-life, high-reliability requirements of electronic equipment for space applications. This study was directed to the identification of the properties of electrically insulative adhesives that potentially could cause problems in such an application, and to the development of evaluation tests to quantify these properties and thus form the basis for establishing suitable guidelines and, ultimately, specifications. Bond strength, outgassing after cure, and corrosivity were selected for detailed attention since they are considered to be especially critical. Introductory discussion includes enumeration and brief comments on the properties of adhesives considered to be important for the proposed application, a general review of polymeric types of adhesives, and identification of the major types of adhesives commercially available and specifically designed for microelectronic use. The specific tests developed to evaluate bond strength, outgassing after cure, and corrosivity are discussed in detail, and comparative results obtained for selected adhesives representative of the major types are given.
Energy Technology Data Exchange (ETDEWEB)
Hernandez, C.L.; Vianco, P.T.; Rejent, J.A.
1998-08-01
Although Sn-Pb eutectic alloy is widely used as a joining material in the electronics industry, it has well documented environmental and toxicity issues. Sandia National Laboratories is developing alternative solder materials to replace traditional Pb-containing alloys. The alloys are based on the Sn-Ag, Sn-Ag-Bi and Sn-Ag-Bi-Au systems. Prototype hybrid microcircuit (HMC) test vehicles have been developed to evaluate these Pb-free solders, using Au-Pt-Pd thick film metallization. Populated test vehicles with surface mount devices have been designed and fabricated to evaluate the reliability of surface mount solder joints. The test components consist of a variety of dummy chip capacitors and leadless ceramic chip carriers (LCCC`s). Intermetallic compound (IMC) layer reaction products that form at the solder/substrate interface have been characterized and their respective growth kinetics quantified. Thicker IMC layers pose a potential reliability problem with solder joint integrity. Since the IMC layer is brittle, the likelihood of mechanical failure of a joint in service is increased. The effect of microstructure and the response of these different materials to wetting, aging and mechanical testing was also investigated. Solid-state reaction data for intermetallic formation and mechanical properties of the solder joints are reported.
Mechanical properties of Pb-free solder alloys on thick film hybrid microcircuits
Energy Technology Data Exchange (ETDEWEB)
Hernandez, C.L.; Vianco, P.T.; Rejent, J.A.; Hosking, F.M.
1998-03-10
The technology drivers of the electronics industry continue to be systems miniaturization and reliability, in addition to addressing a variety of important environmental issues. Although the Sn-Pb eutectic alloy is widely used as a joining material in the electronics industry, it has drawn environmental concern due to its Pb content. The solder acts both as an electrical and mechanical connection within the different packaging levels in an electronic device. New Pb-free solders are being developed at Sandia National Laboratories. The alloys are based on the Sn-Ag alloy, having Bi and Au additions. Prototype hybrid microcircuit (HMC) test vehicles have been assembled to evaluate Pb-free solders for Au-Pt-Pd thick film soldering. The test components consist of a variety of dummy chip capacitors and leadless ceramic chip carriers (LCCC`s). The mechanical properties of the joints were evaluated. The reflow profiles and the solid state intermetallic formation reaction will also be presented. Improved solder joint manufacturability and increased fatigue resistance solder alloys are the goals of these materials.
A hermetic sealing process for large irregularly shaped hybrid microcircuit enclosures
Stahler, M. R.
1977-01-01
A system for sealing vacuum baked hybrids in a dry inert atmosphere using an overlapping spot resistance weld is described. A unique electrode configuration and fixturing that permits sealing of large and irregularly shaped gold plated Kovar packages to the hermeticity requirements of MIL-STD-883 was discussed. Metallurgical considerations and comparisons to laser sealing were made. Problems encountered during the development and optimization of the process were highlighted. Solutions to plating, fixturing, warpage, weld splatter and cracked bead problems are presented.
Phase reduction theory for hybrid nonlinear oscillators
Shirasaka, Sho; Kurebayashi, Wataru; Nakao, Hiroya
2017-01-01
Hybrid dynamical systems characterized by discrete switching of smooth dynamics have been used to model various rhythmic phenomena. However, the phase reduction theory, a fundamental framework for analyzing the synchronization of limit-cycle oscillations in rhythmic systems, has mostly been restricted to smooth dynamical systems. Here we develop a general phase reduction theory for weakly perturbed limit cycles in hybrid dynamical systems that facilitates analysis, control, and optimization of nonlinear oscillators whose smooth models are unavailable or intractable. On the basis of the generalized theory, we analyze injection locking of hybrid limit-cycle oscillators by periodic forcing and reveal their characteristic synchronization properties, such as ultrafast and robust entrainment to the periodic forcing and logarithmic scaling at the synchronization transition. We also illustrate the theory by analyzing the synchronization dynamics of a simple physical model of biped locomotion.
Energy Technology Data Exchange (ETDEWEB)
Adams, B.E.
1997-02-01
Two cleaning processes, one aqueous and one nonaqueous, were investigated as potential replacements for the vapor degreasing process using 1,1,1 trichloroethane (TCA) for hybrid microcircuit assemblies. The aqueous process was based upon saponification chemistry. A 10% solution of either Kester 5768 or Armakleen 2001, heated to 140 F, was sprayed on the hybrid at 450 psig and a flow rate of 5 gpm through a specially designed nozzle which created microdroplets. The nonaqueous process was based upon dissolution chemistry and used d-limonene as the solvent in an immersion and spray process. The d-limonene solvent was followed by an isopropyl alcohol spray rinse to remove the excess d-limonene. The aqueous microdroplet process was found to be successful only for solder reflow profiles that did not exceed 210 C. Furthermore, removal of component marking was a problem and the spray pressure had to be reduced to 130 psig to eliminate damage to capacitor end caps. The d-limonene cleaning was found to be successful for solder reflow temperature up to 250 C when using a four-step cleaning process. The four steps included refluxing the hybrid at 80 C, followed by soaking the hybrid in d-limonene which is heated to 80 C, followed by spray cleaning at 80 psig with room temperature d-limonene, followed by spray cleaning at 80 psig with room temperature IPA was developed to remove residual flux from the hybrid microcircuits. This process was the most robust and most closely matched the cleaning ability of TCA.
Directory of Open Access Journals (Sweden)
Junwei Sun
2014-01-01
Full Text Available Some important dynamical properties of the memristor chaotic oscillator system have been studied in the paper. A novel hybrid dislocated control method and a general hybrid projective dislocated synchronization scheme have been realized for memristor chaotic oscillator system. The paper firstly presents hybrid dislocated control method for stabilizing chaos to the unstable equilibrium point. Based on the Lyapunov stability theorem, general hybrid projective dislocated synchronization has been studied for the drive memristor chaotic oscillator system and the same response memristor chaotic oscillator system. For the different dimensions, the memristor chaotic oscillator system and the other chaotic system have realized general hybrid projective dislocated synchronization. Numerical simulations are given to show the effectiveness of these methods.
Application of Hybrid Functions for Solving Duffing-Harmonic Oscillator
Directory of Open Access Journals (Sweden)
Mohammad Heydari
2014-01-01
Full Text Available A numerical method for finding the solution of Duffing-harmonic oscillator is proposed. The approach is based on hybrid functions approximation. The properties of hybrid functions that consist of block-pulse and Chebyshev cardinal functions are discussed. The associated operational matrices of integration and product are then utilized to reduce the solution of a strongly nonlinear oscillator to the solution of a system of algebraic equations. The method is easy to implement and computationally very attractive. The results are compared with the exact solution and results from several recently published methods, and the comparisons showed proper accuracy of this method.
Early Oscillation Detection Technique for Hybrid DC/DC Converters
Wang, Bright L.
2011-01-01
Oscillation or instability is a situation that must be avoided for reliable hybrid DC/DC converters. A real-time electronics measurement technique was developed to detect catastrophic oscillations at early stages for hybrid DC/DC converters. It is capable of identifying low-level oscillation and determining the degree of the oscillation at a unique frequency for every individual model of the converters without disturbing their normal operations. This technique is specially developed for space-used hybrid DC/DC converters, but it is also suitable for most of commercial and military switching-mode power supplies. This is a weak-electronic-signal detection technique to detect hybrid DC/DC converter oscillation presented as a specific noise signal at power input pins. It is based on principles of feedback control loop oscillation and RF signal modulations, and is realized by using signal power spectral analysis. On the power spectrum, a channel power amplitude at characteristic frequency (CPcf) and a channel power amplitude at switching frequency (CPsw) are chosen as oscillation level indicators. If the converter is stable, the CPcf is a very small pulse and the CPsw is a larger, clear, single pulse. At early stage of oscillation, the CPcf increases to a certain level and the CPsw shows a small pair of sideband pulses around it. If the converter oscillates, the CPcf reaches to a higher level and the CPsw shows more high-level sideband pulses. A comprehensive stability index (CSI) is adopted as a quantitative measure to accurately assign a degree of stability to a specific DC/DC converter. The CSI is a ratio of normal and abnormal power spectral density, and can be calculated using specified and measured CPcf and CPsw data. The novel and unique feature of this technique is the use of power channel amplitudes at characteristic frequency and switching frequency to evaluate stability and identify oscillations at an early stage without interfering with a DC/DC converter s
Spin-dependent terahertz oscillator based on hybrid graphene superlattices
Energy Technology Data Exchange (ETDEWEB)
Díaz, E.; Miralles, K.; Domínguez-Adame, F. [GISC, Departamento Física de Materiales, Universidad Complutense, E-28040 Madrid (Spain); Gaul, C., E-mail: cgaul@pks.mpg.de [Max Planck Institute for the Physics of Complex Systems, 01187 Dresden (Germany)
2014-09-08
We theoretically study the occurrence of Bloch oscillations in biased hybrid graphene systems with spin-dependent superlattices. The spin-dependent potential is realized by a set of ferromagnetic insulator strips deposited on top of a gapped graphene nanoribbon, which induce a proximity exchange splitting of the electronic states in the graphene monolayer. We numerically solve the Dirac equation and study Bloch oscillations in the lowest conduction band of the spin-dependent superlattice. While the Bloch frequency is the same for both spins, we find the Bloch amplitude to be spin dependent. This difference results in a spin-polarized ac electric current in the THz range.
Cellular signalling properties in microcircuits
DEFF Research Database (Denmark)
Toledo-Rodriguez, Maria; El Manira, Abdeljabbar; Wallén, Peter
2005-01-01
Molecules and cells are the signalling elements in microcircuits. Recent studies have uncovered bewildering diversity in postsynaptic signalling properties in all areas of the vertebrate nervous system. Major effort is now being invested in establishing the specialized signalling properties at th...
Stable local oscillator module.
Energy Technology Data Exchange (ETDEWEB)
Brocato, Robert Wesley
2007-11-01
This report gives a description of the development of a Stable Local Oscillator (StaLO) multi-chip module (MCM). It is a follow-on report to SAND2006-6414, Stable Local Oscillator Microcircuit. The StaLO accepts a 100MHz input signal and produces output signals at 1.2, 3.3, and 3.6 GHz. The circuit is built as a multi-chip module (MCM), since it makes use of integrated circuit technologies in silicon and lithium niobate as well as discrete passive components. This report describes the development of an MCM-based version of the complete StaLO, fabricated on an alumina thick film hybrid substrate.
The dynamics of hybrid metabolic-genetic oscillators
Reznik, Ed; Kaper, Tasso J.; Segrè, Daniel
2013-03-01
The synthetic construction of intracellular circuits is frequently hindered by a poor knowledge of appropriate kinetics and precise rate parameters. Here, we use generalized modeling (GM) to study the dynamical behavior of topological models of a family of hybrid metabolic-genetic circuits known as "metabolators." Under mild assumptions on the kinetics, we use GM to analytically prove that all explicit kinetic models which are topologically analogous to one such circuit, the "core metabolator," cannot undergo Hopf bifurcations. Then, we examine more detailed models of the metabolator. Inspired by the experimental observation of a Hopf bifurcation in a synthetically constructed circuit related to the core metabolator, we apply GM to identify the critical components of the synthetically constructed metabolator which must be reintroduced in order to recover the Hopf bifurcation. Next, we study the dynamics of a re-wired version of the core metabolator, dubbed the "reverse" metabolator, and show that it exhibits a substantially richer set of dynamical behaviors, including both local and global oscillations. Prompted by the observation of relaxation oscillations in the reverse metabolator, we study the role that a separation of genetic and metabolic time scales may play in its dynamics, and find that widely separated time scales promote stability in the circuit. Our results illustrate a generic pipeline for vetting the potential success of a circuit design, simply by studying the dynamics of the corresponding generalized model.
Sub-femtosecond absolute timing jitter with a 10 GHz hybrid photonic-microwave oscillator
Fortier, T. M.; Nelson, C. W.; Hati, A.; Quinlan, F.; Taylor, J.; Jiang, H.; Chou, C. W.; Rosenband, T.; Lemke, N.; Ludlow, A.; Howe, D.; Oates, C. W.; Diddams, S. A.
2012-06-01
We present an optical-electronic approach to generating microwave signals with high spectral purity. By circumventing shot noise and operating near fundamental thermal limits, we demonstrate 10 GHz signals with an absolute timing jitter for a single hybrid oscillator of 420 attoseconds (1 Hz-5 GHz).
Oscillation of an anuran hybrid zone: morphological evidence spanning 50 years.
Directory of Open Access Journals (Sweden)
Jean-Sébastien Roy
Full Text Available BACKGROUND: The hybrid zone between the primarily forest-dwelling American toad, Anaxyrus americanus, and the prairie-adapted Canadian toad, A. hemiophrys, in southeastern Manitoba is known to have shifted its position during the past 50 years. Hybrid zones are areas of interbreeding between species and their movement across a landscape should reflect their underlying dynamics and environmental change. However, empirical demonstrations of hybrid zone movements over long periods of time are rare. This hybrid zone is dominated by individuals of intermediate morphology and genetic composition. We sought to determine if it had continued to move and if that movement was associated with shifts in habitat, as predicted. METHODOLOGY/PRINCIPLE FINDINGS: We used variation in the toads' most diagnostic morphological feature, the separation between their interorbital cranial crests, to determine the geographic position of the hybrid zone center at four times between 1960 and 2009 using maximum likelihood methods. The hybrid zone center moved west by 38 km over 19 years and then east again by 10 km over the succeeding 29 years. The position of the hybrid zone did not track either the direction or the magnitude of movement of the forest-prairie habitat transition over the same time period. CONCLUSIONS/SIGNIFICANCE: This is the first reported evidence of oscillation in the position of a hybrid zone. The back and forth movement indicates that neither species maintains a selective advantage over the other in the long term. However, the movement of the hybrid zone was not bounded by the breadth of the habitat transition. Its oscillation suggests that the hybrid zone is better described as being elastically tethered to the habitat transition.
High- T_c superconducting thin film/GaAs MESFET hybrid microwave oscillator
Institute of Scientific and Technical Information of China (English)
金飚兵; 康琳; 伍瑞新; 张健羽; 程其恒; 吴培亨; 经东; 焦刚; 邵凯; 蒋明明; 张家宗; 孙敏松; 王蕴仪; 周岳亮; 吕惠宾; 许世发; 何萌; 王小平; 杨秉川; 卢剑; 张其邵
1997-01-01
A high- Tc superconducting (HTSC) thin film/GaAs MESFET hybrid microwave oscillator operated at 10 6 GHz has been designed, fabricated and characterized. Microstrip line structures were used throughout the circuit with superconducting thin film YBaiCuiO7 8(YBCO) as the conductor material. The YBCO thin films were deposited on 15 mm×10 mm×0. 5 mm LaAlO3 substrates. The oscillator was common-source, series feedback type using a GaAs-MESFET (NE72084) as the active device and a superconducting microstrip resonator as the frequency stabilizing element. By improving the unloaded quality factor Q0 of the superconducting microstrip resonator and adjusting the coupling coefficient between the resonator and the gate of the MESFET, the phase noise of the oscillator was decreased At 77 K, the phase noise of the oscillator at 10 kHz offset from carrier was - 87 dBc/Hz.
Towards a 'canonical' agranular cortical microcircuit
Directory of Open Access Journals (Sweden)
Sarah F. Beul
2015-01-01
Full Text Available Based on regularities in the intrinsic microcircuitry of cortical areas, variants of a 'canonical' cortical microcircuit have been proposed and widely adopted, particularly in computational neuroscience and neuroinformatics. However, this circuit is founded on striate cortex, which manifests perhaps the most extreme instance of cortical organization, in terms of a very high density of cells in highly differentiated cortical layers. Most other cortical regions have a less well differentiated architecture, stretching in gradients from the very dense eulaminate primary cortical areas to the other extreme of dysgranular and agranular areas of low density and poor laminar differentiation. It is unlikely for the patterns of inter- and intra-laminar connections to be uniform in spite of strong variations of their structural substrate. This assumption is corroborated by reports of divergence in intrinsic circuitry across the cortex. Consequently, it remains an important goal to define local microcircuits for a variety of cortical types, in particular, agranular cortical regions. As a counterpoint to the striate microcircuit, which may be anchored in an exceptional cytoarchitecture, we here outline a tentative microcircuit for agranular cortex. The circuit is based on a synthesis of the available literature on the local microcircuitry in agranular cortical areas of the rodent brain, investigated by anatomical and electrophysiological approaches. A central observation of these investigations is a weakening of interlaminar inhibition as cortical cytoarchitecture becomes less distinctive. Thus, our study of agranular microcircuitry revealed deviations from the well-known 'canonical' microcircuit established for striate cortex, suggesting variations in the intrinsic circuitry across the cortex that may be functionally relevant.
Zheng, Ming Jie; Wang, Gang; Yu, Kin Wah
2010-12-01
We have studied the optical oscillation and tunneling of light waves in optical waveguide ladders (OWLs) formed by two coupled planar optical waveguide arrays. For the band structure, a midzone gap is formed owing to band hybridization, and its wavenumber position can be tuned throughout the whole Brillouin zone, which is different from the Bragg gap. By imposing a gradient in the propagation constant in each array, Bloch-Zener oscillation (BZO) is realized with Zener tunneling between the bands occurring at the midzone, which is contrary to the common BZO with tunneling at the center or edge of the Brillouin zone. The occurrence of BZO is demonstrated by using the field-evolution analysis. The tunable hybridization at the midzone enhances the tunability of BZO in the OWLs. This Letter may offer new insights into the coherent phenomena in optical lattices.
Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit
Prince, Luke Y.; Bacon, Travis J.; Tigaret, Cezar M.; Mellor, Jack R.
2016-01-01
The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval. PMID:27799909
Neuromodulation of the feedforward dentate gyrus-CA3 microcircuit
Luke Yuri Prince; Travis J Bacon; Tigaret, Cezar M.; Mellor, Jack R.
2016-01-01
The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on...
Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit
Prince, Luke; Travis J Bacon; Tigaret, Cezar; Mellor, Jack
2016-01-01
The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on...
Neuromodulation of the Feedforward Dentate Gyrus-CA3 Microcircuit.
Prince, Luke Y; Bacon, Travis J; Tigaret, Cezar M; Mellor, Jack R
2016-01-01
The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval.
The technology of microcircuit assembly on flexible polyimide substrate
Directory of Open Access Journals (Sweden)
Plis N. I.
2010-10-01
Full Text Available The research is devoted to technology of microcircuit assembly on flexible polyimide substrate. It is proved that such microcircuits provide high reliability and have advantage over other IC models when applied in hermetic micro-assemblies in microelectronic devices that operate under high accelerations, shocks and strong radiation.
Weak Forces and Neutrino Oscillations under the standards of Hybrid Gravity with Torsion
Capozziello, Salvatore; Vignolo, Stefano
2013-01-01
We present a unifying approach where weak forces and neutrino oscillations are interpreted under the same standards of torsional hybrid gravity. This gravitational theory mixes metric and metric-affine formalism in presence of torsion and allows to derive an effective scalar field which gives rise to a running coupling for Dirac matter fields. In this picture, two phenomena occurring at different energy scales can be encompassed under the dynamics of such a single scalar field, which represents the further torsional and curvature degrees of freedom
Fauché, Pierre; Kosionis, Spyridon G.; Lalanne, Philippe
2017-05-01
There is considerable interest in collective effects in hybrid systems formed by molecular or atomic ensembles strongly coupled by an electromagnetic resonance. For analyzing such collective effects, we develop an efficient and general theoretical formalism based on the natural modes of the resonator. The main strength of our approach is its generality and the high level of analyticity enabled by modal analysis, which allows one to model complex hybrid systems without any restriction on the resonator shapes or material properties, and to perform statistical computations to predict general properties that are robust to spatial and polarization disorders. Most notably, we establish that super-radiant modes remain even after ensemble averaging and act as an "invisibility cloak" with a spectral bandwidth that scales with the number of oscillators and the spatially averaged Purcell factor.
Microcircuit failure analysis using the SEM. [Scanning Electron Microscopes
Nicolas, D. P.
1974-01-01
The scanning electron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.
Neuromodulation of the feedforward dentate gyrus-CA3 microcircuit
Directory of Open Access Journals (Sweden)
Luke Yuri Prince
2016-10-01
Full Text Available The feedforward dentate gyrus-CA3 microcircuit in the hippocampus is thought to activate ensembles of CA3 pyramidal cells and interneurons to encode and retrieve episodic memories. The creation of these CA3 ensembles depends on neuromodulatory input and synaptic plasticity within this microcircuit. Here we review the mechanisms by which the neuromodulators aceylcholine, noradrenaline, dopamine, and serotonin reconfigure this microcircuit and thereby infer the net effect of these modulators on the processes of episodic memory encoding and retrieval.
Electromagnetic radiation screening of microcircuits for long life applications
Brammer, W. G.; Erickson, J. J.; Levy, M. E.
1974-01-01
The utility of X-rays as a stimulus for screening high reliability semiconductor microcircuits was studied. The theory of the interaction of X-rays with semiconductor materials and devices was considered. Experimental measurements of photovoltages, photocurrents, and effects on specified parameters were made on discrete devices and on microcircuits. The test specimens included discrete devices with certain types of identified flaws and symptoms of flaws, and microcircuits exhibiting deviant electrical behavior. With a necessarily limited sample of test specimens, no useful correlation could be found between the X-ray-induced electrical response and the known or suspected presence of flaws.
Duan, Wenye; Wang, Wei; Zhang, Chao; Jin, Kuijuan; Ma, Zhongshui
2016-10-01
The proximity properties of edge currents in the vicinity of the interface between the graphene and superconductor in the presence of magnetic field are investigated. It is shown that the edge states introduced by Andreev reflection at the graphene-superconductor (G/S) interface give rise to the charge neutral states in all Landau levels. We note that in a topological insulator-superconductor (TI/S) hybrid structure, only N = 0 Landau level can support this type of charge neutral states. The different interface states of a G/S hybrid and a TI/S hybrid is due to that graphene consists of two distinct sublattices. The armchair edge consists of two inequivalent atoms. This gives rise to unique electronic properties of edge states when connected to a superconductor. A direct consequence of zero charge states in all Landau levels is that the current density approaches zero at interface. The proximity effect leads to quantum magnetic oscillation of the current density in the superconductor region. The interface current density can also be tuned with a finite interface potential. For sharp δ-type interface potential, the derivative of the wavefunction is discontinuous. As a result, we found that there is current density discontinuity at the interface. The step of the current discontinuity is proportional to the strength of the interface potential.
Research News: Are VLSI Microcircuits Too Hard to Design?
Robinson, Arthur L.
1980-01-01
This research news article on microelectronics discusses the scientific challenge the integrated circuit industry will have in the next decade, for designing the complicated microcircuits made possible by advancing miniaturization technology. (HM)
A hybrid formulation to suppress the numerical oscillations caused by immersed moving boundaries
Luo, Haoxiang; Dai, Hu; Ferreira de Sousa, Paulo
2009-11-01
A family of immersed-boundary methods, based on the sharp-interface representation of the boundary and local interpolation/extrapolation, has been recently developed to handle complex and moving boundary problems encountered in biological flows. Implemented typically on structured meshes, these methods save the computational cost of grid generation and take advantage of efficient computations on structured grids. However, since some of the nodes near the immersed boundary do not have the regular finite-difference stencil available for discretizing the Navier-Stokes equation, a local interpolation or extrapolation scheme is often used to reconstruct the flow field around the nodes. The drawback of this approach is that when a non-stationary boundary moves across the mesh points, the change of the stencil for the solution reconstruction causes artificial oscillations in the pressure. To suppress the oscillations, we have introduced a set of hybrid nodes on which both the Navier-Stokes solution and flow reconstruction are sought, and they are weighted according to the distance to the immersed boundary. The method has been implemented in both two- and three-dimensional solvers to handle a class of biological locomotion problems including flow-structure interaction. The accuracy and capability of the solvers will be demonstrated.
Critical Current Oscillations in the Intrinsic Hybrid Vortex State of SmFeAs(O,F)
Moll, Philip J. W.; Balicas, Luis; Zhu, Xiyu; Wen, Hai-Hu; Zhigadlo, Nikolai D.; Karpinski, Janusz; Batlogg, Bertram
2014-10-01
In layered superconductors the order parameter may be modulated within the unit cell, leading to nontrivial modifications of the vortex core if the interlayer coherence length ξc(T ) is comparable to the interlayer spacing. In the iron pnictide SmFeAs(O,F) (Tc≈50 K ) this occurs below a crossover temperature T⋆≈41 K , which separates two regimes of vortices: anisotropic Abrikosov-like at high and Josephson-like at low temperatures. Yet in the transition region around T⋆ , hybrid vortices between these two characteristics appear. Only in this region around T⋆ and for magnetic fields well aligned with the FeAs layers, we observe oscillations of the c -axis critical current jc(H ) periodic in 1 /√{H } due to a delicate balance of intervortex forces and interaction with the layered potential. jc(H ) shows pronounced maxima when a hexagonal vortex lattice is commensurate with the underlying crystal structure. The narrow temperature window in which oscillations are observed suggests a significant suppression of the order parameter between the superconducting layers in SmFeAs(O,F), despite its low coherence length anisotropy (γξ≈3 - 5 ).
Pain processing by spinal microcircuits: afferent combinatorics.
Prescott, Steven A; Ratté, Stéphanie
2012-08-01
Pain, itch, heat, cold, and touch represent different percepts arising from somatosensory input. How stimuli give rise to these percepts has been debated for over a century. Recent work supports the view that primary afferents are highly specialized to transduce and encode specific stimulus modalities. However, cross-modal interactions (e.g. inhibition or exacerbation of pain by touch) support convergence rather than specificity in central circuits. We outline how peripheral specialization together with central convergence could enable spinal microcircuits to combine inputs from distinctly specialized, co-activated afferents and to modulate the output signals thus formed through computations like normalization. These issues will be discussed alongside recent advances in our understanding of microcircuitry in the superficial dorsal horn.
Asgekar, V; Lehnert, U; Michel, P
2012-01-01
A tapered undulator experiment was carried out at the ELBE far-infrared free electron laser (FEL). The oscillator FEL makes use of a hybrid optical resonator. The main motivation was to see whether the presence of a dispersive medium in the form of a waveguide in the resonator has any effect on the outcome. The FEL saturated power and the wavelength shifts have been measured as a function of both positive as well as negative undulator field amplitude tapering. In contrast to the typical high-gain FELs where positive tapering proves beneficial for the output power we observed an improvement of performance at negative taper. During the same experiments we studied the characteristics of the detuning curves. The width of the curves indicates a maximum small signal gain for zero taper while the output peak power increases with negative taper. The saturated power output, the detuning curve characteristics, and the wavelength shifts agrees with the theoretical predictions. Details of the experiment are presented.
FPGA Simulation Engine for Customized Construction of Neural Microcircuits.
Blair, Hugh T; Cong, Jason; Wu, Di
2013-04-01
In this paper we describe an FPGA-based platform for high-performance and low-power simulation of neural microcircuits composed from integrate-and-fire (IAF) neurons. Based on high-level synthesis, our platform uses design templates to map hierarchies of neuron model to logic fabrics. This approach bypasses high design complexity and enables easy optimization and design space exploration. We demonstrate the benefits of our platform by simulating a variety of neural microcircuits that perform oscillatory path integration, which evidence suggests may be a critical building block of the navigation system inside a rodent's brain. Experiments show that our FPGA simulation engine for oscillatory neural microcircuits can achieve up to 39× speedup compared to software benchmarks on commodity CPU, and 232× energy reduction compared to embedded ARM core.
Directory of Open Access Journals (Sweden)
Efstathios D Kondylis
2014-08-01
Full Text Available High frequency oscillations (HFOs have been proposed as a novel marker for epileptogenic tissue, spurring tremendous research interest into the characterization of these transient events. A wealth of continuously recorded intracranial electroencephalographic (iEEG data is currently available from patients undergoing invasive monitoring for the surgical treatment of epilepsy. In contrast to data recorded on research-customized recording systems, data from clinical acquisition systems remain an underutilized resource for HFO detection in most centers. The effective and reliable use of this clinically obtained data would be an important advance in the ongoing study of HFOs and their relationship to ictogenesis. The diagnostic utility of HFOs ultimately will be limited by the ability of clinicians to detect these brief, sporadic, and low amplitude events in an electrically noisy clinical environment. Indeed, one of the most significant factors limiting the use of such clinical recordings for research purposes is their low signal to noise ratio, especially in the higher frequency bands. In order to investigate the presence of HFOs in clinical data, we first obtained continuous intracranial recordings in a typical clinical environment using a commercially available, commonly utilized data acquisition system and off the shelf hybrid macro/micro depth electrodes. This data was then inspected for the presence of HFOs using semi-automated methods and expert manual review. With targeted removal of noise frequency content, HFOs were detected on both macro- and micro-contacts, and preferentially localized to seizure onset zones. HFOs detected by the offline, semi-automated method were also validated in the clinical viewer, demonstrating that 1 this clinical system allows for the visualization of HFOs, and 2 with effective signal processing, clinical recordings can yield valuable information for offline analysis.
Hybrid microcircuit metallization system for the SLL micro actuator
Energy Technology Data Exchange (ETDEWEB)
Hampy, R. E.; Knauss, G. L.; Komarek, E. E.; Kramer, D. K.; Villaueva, J.
1976-03-01
A thin film technique developed for the SLL Micro Actuator in which both gold and aluminum can be incorporated on sapphire or fine grained alumina substrates in a two-level metallization system is described. Tungsten is used as a lateral transition metal permitting electrical contact between the gold and aluminum without the two metals coming in physical contact. Silicon dioxide serves as an insulator between the tungsten and aluminum for crossover purposes, and vias through the silicon dioxide permit interconnections where desired. Tungsten-gold is the first level conductor except at crossovers where tungsten only is used and aluminum is the second level conductor. Sheet resistances of the two levels can be as low as 0.01 ohm/square. Line widths and spaces as small as 0.025 mm can be attained. A second layer of silicon dioxide is deposited over the metallization and opened for all gold and aluminum bonding areas. The metallization system permits effective interconnection of a mixture of devices having both gold and aluminum terminations without creating undesirable gold-aluminum interfaces. Processing temperatures up to 400/sup 0/C can be tolerated for short times without effect on bondability, conductor, and insulator characteristics, thus permitting silicon-gold eutectic die attachment, component soldering, and higher temperatures during gold lead bonding. Tests conducted on special test pattern circuits indicate good stability over the temperature range -55 to +150/sup 0/C. Aging studies indicate no degradation in characteristics in tests of 500 h duration at 150/sup 0/C.
Structured Connectivity Shapes Microcircuit Function in the Prefrontal Cortex.
Directory of Open Access Journals (Sweden)
Stefanos Stefanou - Stamatiadis
2014-03-01
Full Text Available The application of new experimental techniques in vivo has shed light on the wiring diagram of cortical networks, revealing the highly non-random connectivity of pyramidal neurons. This structured connectivity is characterized by distance-dependent formation of neuronal clusters and over-represented structural ‘motifs’ (Perin 2011, Ko 2013. In the prefrontal cortex (PFC in particular, pyramidal neurons were shown to form hyper-clusters, compared to other sensory regions. Yet, very little is known about the functional properties of these microcircuits and their role in Persistent Activity (PA, a well known function of the PFC. PA is the spiking activity that persists beyond the stimulus presentation and is considered to be the cellular correlate of working memory. Although, PA was traditionally assumed to emerge in large scale networks, recent in vivo data in the PFC suggest that small microcircuits mediate its functional output (Durstwitz, 2010. Motivated by the above findings this work probes the role of realistic connectivity constraints in shaping the functional output of PFC, through simulations of biophysically and morphologically detailed PFC circuits. Towards this goal, we used a compartmental modeling approach, whereby layer 5 PFC pyramidal neurons are modeled with detailed morphological and biophysical properties. Three different types of interneurons were also implemented; the Fast-spiking (FS, Regular-spiking (RS, and Irregular-spiking (IS. These were biophysically detailed, yet morphologically simplified. Microcircuits consisted of 75 pyramidal neurons, 13 FS, 6 RS and 6 IS. Properties (location /number /amplitude /kinetics of both excitatory and inhibitory synapses were extensively validated against experimental data. The network model was used to investigate the effect of connectivity on the emergence of persistent activity. Two different connectivity profiles of pyramidal cells were implemented: one highly non
Design, processing and testing of LSI arrays: Hybrid microelectronics task
Himmel, R. P.; Stuhlbarg, S. M.; Ravetti, R. G.; Zulueta, P. J.
1979-01-01
Mathematical cost factors were generated for both hybrid microcircuit and printed wiring board packaging methods. A mathematical cost model was created for analysis of microcircuit fabrication costs. The costing factors were refined and reduced to formulae for computerization. Efficient methods were investigated for low cost packaging of LSI devices as a function of density and reliability. Technical problem areas such as wafer bumping, inner/outer leading bonding, testing on tape, and tape processing, were investigated.
Three-dimensional mapping of microcircuit correlation structure
Directory of Open Access Journals (Sweden)
R. James eCotton
2013-10-01
Full Text Available Great progress has been made towards understanding the properties of single neurons, yet the principles underlying interactions between neurons remain poorly understood. Given that connectivity in the neocortex is locally dense through both horizontal and vertical con-nections, it is of particular importance to characterize the activity structure of local popula-tions of neurons arranged in three dimensions. However, techniques for simultaneously measuring microcircuit activity are lacking. We developed an in vivo 3D high-speed, ran-dom-access two-photon microscope that is capable of simultaneous 3D motion tracking. This allows imaging from hundreds of neurons at several hundred Hz, while monitoring tissue movement. Given that motion will induce common artifacts across the population, accurate motion tracking is absolutely necessary for studying population activity with ran-dom-access based imaging methods. We demonstrate the potential of this imaging tech-nique by measuring the correlation structure of large populations of nearby neurons in the mouse visual cortex, and find that the microcircuit correlation structure is stimulus-dependent. Three-dimensional random access multiphoton imaging with concurrent mo-tion tracking provides a novel powerful method to characterize the microcircuit activity in vivo.
Qualification status of hybrid crystal oscillators style OTO 16S for space application
Gerard, E.; Deviller, J. L.
1991-03-01
The qualification status of a crystal clock oscillator, OTO 16S, is described. Specifically designed for the Telecom 2 and Intelsat 7 programs, the oscillator is available in frequencies between 3 and 25 MHz with Transistor Transistor Logic (TTL) compatible outputs. Qualification tests results are presented to demonstrate that all the OTO 16S performances are in compliance with space requirements. From a mechanical viewpoint, no degradation is seen from a vibration level of 50 g sinus 10 to 2000 Hz. From a life test viewpoint, no significant variations are observed after 2000 hours of testing.
Yashin, Victor V; Levitan, Steven P; Balazs, Anna C
2015-06-24
Lightweight, deformable materials that can sense and respond to human touch and motion can be the basis of future wearable computers, where the material itself will be capable of performing computations. To facilitate the creation of "materials that compute", we draw from two emerging modalities for computation: chemical computing, which relies on reaction-diffusion mechanisms to perform operations, and oscillatory computing, which performs pattern recognition through synchronization of coupled oscillators. Chemical computing systems, however, suffer from the fact that the reacting species are coupled only locally; the coupling is limited by diffusion as the chemical waves propagate throughout the system. Additionally, oscillatory computing systems have not utilized a potentially wearable material. To address both these limitations, we develop the first model for coupling self-oscillating polymer gels to a piezoelectric (PZ) micro-electro-mechanical system (MEMS). The resulting transduction between chemo-mechanical and electrical energy creates signals that can be propagated quickly over long distances and thus, permits remote, non-diffusively coupled oscillators to communicate and synchronize. Moreover, the oscillators can be organized into arbitrary topologies because the electrical connections lift the limitations of diffusive coupling. Using our model, we predict the synchronization behavior that can be used for computational tasks, ultimately enabling "materials that compute".
Institute of Scientific and Technical Information of China (English)
Md Riyad Tanshen; Sinil Lee; Junhyo Kim; Donghoon Kang; Jungpil Noh; HanShik Chung; HyoMin Jeong; Sunchul Huh
2014-01-01
Effective thermal performance of oscillating heat pipe (OHP) is driven by inside pressure distribution. Heat transfer phenomena were reported in terms of pressure and frequency of pressure fluctuation in multi loop OHP charged with aqueous Al2O3 and MWCNTs/Al2O3 nanoparticles. The influences on thermal resistance of aqueous Al2O3, MWCNTs as well as the hybrid of them in OHP having 3 mm in inner diameter were investigated at 60% filling ratio. Experimental results show that thermal characteristics are significantly inter-related with pressure distribution and strongly depend upon the number of pressure fluctuations with time. Frequency of pressure depends upon the power input in evaporative section. A little inclusion of MWCNTs into aqueous Al2O3 at 60% filling ratio achieves the highest fluctuation frequency and the lowest thermal resistance at any evaporator power input though different nanofluids cause different thermal performances of OHPs.
Thick film fabrication of aluminum nitride microcircuits. Final report
Energy Technology Data Exchange (ETDEWEB)
Perdieu, L.H.
1994-03-01
A new substrate material, aluminum nitride (AlN), and 11 new thick film inks were analyzed to determine their chemical compatibility, their electrical properties, their mechanical properties, and their overall suitability for use in the manufacturing of high-power microcircuits with efficient thermal properties. Because high-power chips emit a great deal of heat in a small surface area, a new substrate material was needed to dissipate that heat faster than the substrate material currently in use. Overall, the new materials were found to be acceptable for accomplishing this purpose.
Transient and steady-state selection in the striatal microcircuit.
Tomkins, Adam; Vasilaki, Eleni; Beste, Christian; Gurney, Kevin; Humphries, Mark D
2013-01-01
Although the basal ganglia have been widely studied and implicated in signal processing and action selection, little information is known about the active role the striatal microcircuit plays in action selection in the basal ganglia-thalamo-cortical loops. To address this knowledge gap we use a large scale three dimensional spiking model of the striatum, combined with a rate coded model of the basal ganglia-thalamo-cortical loop, to asses the computational role the striatum plays in action selection. We identify a robust transient phenomena generated by the striatal microcircuit, which temporarily enhances the difference between two competing cortical inputs. We show that this transient is sufficient to modulate decision making in the basal ganglia-thalamo-cortical circuit. We also find that the transient selection originates from a novel adaptation effect in single striatal projection neurons, which is amenable to experimental testing. Finally, we compared transient selection with models implementing classical steady-state selection. We challenged both forms of model to account for recent reports of paradoxically enhanced response selection in Huntington's disease patients. We found that steady-state selection was uniformly impaired under all simulated Huntington's conditions, but transient selection was enhanced given a sufficient Huntington's-like increase in NMDA receptor sensitivity. Thus our models provide an intriguing hypothesis for the mechanisms underlying the paradoxical cognitive improvements in manifest Huntington's patients.
Transient and steady-state selection in the striatal microcircuit
Directory of Open Access Journals (Sweden)
Adam eTomkins
2014-01-01
Full Text Available Although the basal ganglia have been widely studied and implicated in signal processing and action selection, little information is known about the active role the striatal microcircuit plays in action selection in the basal ganglia-thalamo-cortical loops. To address this knowledge gap we use a large scale three dimensional spiking model of the striatum, combined with a rate coded model of the basal ganglia-thalamo-cortical loop, to asses the computational role the striatum plays in action selection. We identify a robust transient phenomena generated by the striatal microcircuit, which temporarily enhances the difference between two competing cortical inputs. We show that this transient is sufficient to modulate decision making in the basal ganglia-thalamo-cortical circuit. We also find that the transient selection originates from a novel adaptation effect in single striatal projection neurons, which is amenable to experimental testing. Finally, we compared transient selection with models implementing classical steady-state selection. We challenged both forms of model to account for recent reports of paradoxically enhanced response selection in Huntington's Disease patients. We found that steady-state selection was uniformly impaired under all simulated Huntington's conditions, but transient selection was enhanced given a sufficient Huntington's-like increase in NMDA receptor sensitivity. Thus our models provide an intriguing hypothesis for the mechanisms underlying the paradoxical cognitive improvements in manifest Huntington's patients.
Voltage stress effects on microcircuit accelerated life test failure rates
Johnson, G. M.
1976-01-01
The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal oxide semiconductor microcircuit operated at six different combinations of temperature and voltage were used to evaluate the models. A total of 450 devices from two different lots were tested at ambient temperatures between 200 C and 250 C and applied voltages between 5 Vdc and 15 Vdc. A statistical analysis of the surface related failure data resulted in bimodal failure distributions comprising two lognormal distributions; a 'freak' distribution observed early in time, and a 'main' distribution observed later in time. The Arrhenius model was shown to provide a good description of device aging as a function of temperature at a fixed voltage. The Eyring model also appeared to provide a reasonable description of main distribution device aging as a function of temperature and voltage. Circuit diagrams are shown.
Accelerated life testing effects on CMOS microcircuit characteristics
1980-01-01
The 250 C, 200C and 125C accelerated tests are described. The wear-out distributions from the 250 and 200 C tests were used to estimate the activation energy between the two test temperatures. The duration of the 125 C test was not sufficient to bring the test devices into the wear-out region. It was estimated that, for the most complex of the three devices types, the activation energy between 200 C and 125 C should be at least as high as that between 250 C and 200 C. The practicality of the use of high temperature for the accelerated life tests from the point of view of durability of equipment is assessed. Guidlines for the development of accelerated life-test conditions are proposed. The use of the silicon nitride overcoat to improve the high temperature accelerated life-test characteristics of CMOS microcircuits is described.
Criteria for robustness of heteroclinic cycles in neural microcircuits
2011-01-01
We introduce a test for robustness of heteroclinic cycles that appear in neural microcircuits modeled as coupled dynamical cells. Robust heteroclinic cycles (RHCs) can appear as robust attractors in Lotka-Volterra-type winnerless competition (WLC) models as well as in more general coupled and/or symmetric systems. It has been previously suggested that RHCs may be relevant to a range of neural activities, from encoding and binding to spatio-temporal sequence generation. The robustness or otherwise of such cycles depends both on the coupling structure and the internal structure of the neurons. We verify that robust heteroclinic cycles can appear in systems of three identical cells, but only if we require perturbations to preserve some invariant subspaces for the individual cells. On the other hand, heteroclinic attractors can appear robustly in systems of four or more identical cells for some symmetric coupling patterns, without restriction on the internal dynamics of the cells. PMID:22656192
Bullock, Daniel; Tan, Can Ozan; John, Yohan J
2009-01-01
Abundant new information about signaling pathways in forebrain microcircuits presents many challenges, and opportunities for discovery, to computational neuroscientists who strive to bridge from microcircuits to flexible cognition and action. Accurate treatment of microcircuit pathways is especially critical for creating models that correctly predict the outcomes of candidate neurological therapies. Recent models are trying to specify how cortical circuits that enable planning and voluntary actions interact with adaptive subcortical microcircuits in the basal ganglia. The basal ganglia are strongly implicated in reinforcement learning, and in all behavior and cognition over which the frontal lobes exert flexible control. The persisting role of the basal ganglia shows that ancient vertebrate designs for motivated action selection proved adaptable enough to support many "modern" behavioral innovations, including fluent generation of language and speech. This paper summarizes how recent models have incorporated realistic representations of microcircuit features, and have begun to trace their computational implications. Also summarized are recent empirical discoveries that provide guidance regarding how to formulate the rules for synaptic modification that govern learning in cortico-striatal pathways. Such efforts are contributing to an emerging synthesis based on an interlocking set of computational hypotheses regarding cortical interactions with basal ganglia and thalamic nuclei. These hypotheses specify how specialized microcircuits solve learning and control problems inherent to the brain's parallel design.
Chakrabarti, R.; Yogesh, V.
2016-04-01
We study the evolution of the hybrid entangled states in a bipartite (ultra) strongly coupled qubit-oscillator system. Using the generalized rotating wave approximation the reduced density matrices of the qubit and the oscillator are obtained. The reduced density matrix of the oscillator yields the phase space quasi probability distributions such as the diagonal P-representation, the Wigner W-distribution and the Husimi Q-function. In the strong coupling regime the Q-function evolves to uniformly separated macroscopically distinct Gaussian peaks representing ‘kitten’ states at certain specified times that depend on multiple time scales present in the interacting system. The ultrastrong coupling strength of the interaction triggers appearance of a large number of modes that quickly develop a randomization of their phase relationships. A stochastic averaging of the dynamical quantities sets in, and leads to the decoherence of the system. The delocalization in the phase space of the oscillator is studied by using the Wehrl entropy. The negativity of the W-distribution reflects the departure of the oscillator from the classical states, and allows us to study the underlying differences between various information-theoretic measures such as the Wehrl entropy and the Wigner entropy. Other features of nonclassicality such as the existence of the squeezed states and appearance of negative values of the Mandel parameter are realized during the course of evolution of the bipartite system. In the parametric regime studied here these properties do not survive in the time-averaged limit.
Cortical microcircuit dynamics mediating Binocular Rivalry: The role of adaptation in inhibition
Directory of Open Access Journals (Sweden)
Panagiota eTheodoni
2011-11-01
Full Text Available Perceptual bistability arises when two conflicting interpretations of an ambiguous stimulus or images in binocular rivalry (BR compete for perceptual dominance. From a computational point of view competition models based on cross-inhibition and adaptation have shown that noise is a crucial force for rivalry and operates in balance with adaptation in order to explain the observed alternations in perception. In particular, noise-driven transitions and adaptation-driven oscillations define two dynamical regimes and the system operates near its boundary. In order to gain insights into the microcircuit dynamics mediating spontaneous perceptual alternations we used a reduced recurrent attractor-based biophysically realistic spiking network well known for working memory, attention and decision-making, where a spike-frequency adaptation mechanism is implemented to account for perceptual bistability. We, thus, derived a consistently reduced four-variable population rate model using mean-field techniques and tested it on BR data collected from human subjects. Our model accounts for experimental data parameters such as time dominance, coefficient of variation and gamma distribution. In addition, we show that our model also operates on the boundary between noise and adaptation and agrees with Levelt’s second revised and fourth propositions. These results show for the first time that a consistent reduction of a biophysically realistic spiking network of integrate and fire neurons with spike frequency adaptation could account for BR. Moreover, we demonstrate that BR can be explained only through the dynamics of the competing neuronal pools, without taking into account the adaptation of inhibitory interneurons..However, adaptation of interneurons affects the optimal parametric space of the system, by decreasing the overall adaptation necessary for the bifurcation to occur.
Directory of Open Access Journals (Sweden)
Cerullo G.
2013-03-01
Full Text Available We demonstrate ultrafast coherent manipulation of the normal mode splitting in metal/molecular-aggregate nanostructures by real-time observation of Rabi oscillations between excitons and surface-plasmon-polaritons. Oscillations in exciton density on a 10-fs timescale control the Rabi splitting.
Dense neuron clustering explains connectivity statistics in cortical microcircuits.
Directory of Open Access Journals (Sweden)
Vladimir V Klinshov
Full Text Available Local cortical circuits appear highly non-random, but the underlying connectivity rule remains elusive. Here, we analyze experimental data observed in layer 5 of rat neocortex and suggest a model for connectivity from which emerge essential observed non-random features of both wiring and weighting. These features include lognormal distributions of synaptic connection strength, anatomical clustering, and strong correlations between clustering and connection strength. Our model predicts that cortical microcircuits contain large groups of densely connected neurons which we call clusters. We show that such a cluster contains about one fifth of all excitatory neurons of a circuit which are very densely connected with stronger than average synapses. We demonstrate that such clustering plays an important role in the network dynamics, namely, it creates bistable neural spiking in small cortical circuits. Furthermore, introducing local clustering in large-scale networks leads to the emergence of various patterns of persistent local activity in an ongoing network activity. Thus, our results may bridge a gap between anatomical structure and persistent activity observed during working memory and other cognitive processes.
Role of cortical feedback in regulating inhibitory microcircuits.
Strowbridge, Ben W
2009-07-01
The olfactory bulb contains an impressive array of specialized inhibitory local circuits. The most frequent inhibitory microcircuit in this brain region is the reciprocal dendrodendritic synapse formed between the lateral dendrites of mitral cells and distal dendritic spines of GABAergic granule cells. Recent work discussed in this review suggests that release of GABA from granule cell spines may reflect near-coincident activation of both mitral cell-to-granule cell synapses and proximal excitatory synapses on granule cells that originate from pyramidal cells in piriform cortex. Recent work using two-photon guided microstimulation demonstrated that proximal and distal excitatory synapses onto granule cells exhibit different forms of short-term plasticity, with feedback inputs from piriform cortex facilitating when tested with brief ( approximately 50 ms) interstimulus intervals. One consequence of this synaptic plasticity is that short duration, gamma-frequency, oscillatory discharges in piriform cortical cells evoke summating excitatory postsynaptic potentials (EPSPs) in granule cells that effectively trigger action potentials. Piriform cortex stimulation can gate dendrodendritic inhibition onto mitral cells, presumably through the ability of EPSP-driven action potentials in granule cells to temporarily relieve the tonic blockade of NMDA receptors by extracellular Mg(2+) ions. Feedback projections in other CNS systems also may target inhibitory neurons, such as the backprojection from CA3 pyramidal neurons to GABAergic hilar interneurons. The ability of downstream processing areas to rapidly and selectively activate inhibitory interneurons in other brain regions may provide an important mechanism to dynamically modulate biological information processing.
Resistance blow-up effect in micro-circuit engineering
Tan, Michael L. P.; Saxena, Tanuj; Arora, Vijay K.
2010-12-01
The nonlinearity in the I- V characteristics of a scaled-down micro/nano-scale resistive channel is shown to elevate the DC and signal resistance as current approaches its saturation value. The deviation from traditional circuit engineering takes place when the applied voltage is increased beyond the critical voltage V c = ( V t/ ℓ) L, where V t is the thermal voltage, ℓ is the ohmic mean free path, and L is the length of the conducting channel. This resistance blow-up is more pronounced for a smaller-length resistor in a micro-circuit of two resistors with same ohmic value. The power consumed P = VI not only is lower but also is a linear function of voltage V as compared to the quadratic rise with V in the ohmic regime. The resistance blow-up effect also gives enhanced RC time constant for transients when a digital signal switches from low to high or vice versa. These results are of immense value to circuit designers and those doing device characterization to extract parasitic and transport parameters.
Neural Dynamics and Information Representation in Microcircuits of Motor Cortex
Directory of Open Access Journals (Sweden)
Yasuhiro eTsubo
2013-05-01
Full Text Available The brain has to analyze and respond to external events that can change rapidly from time to time, suggesting that information processing by the brain may be essentially dynamic rather than static. The dynamical features of neural computation are of significant importance in motor cortex that governs the process of movement generation and learning. In this paper, we discuss these features based primarily on our recent findings on neural dynamics and information coding in the microcircuit of rat motor cortex. In fact, cortical neurons show a variety of dynamical behavior from rhythmic activity in various frequency bands to highly irregular spike firing. Of particular interest are the similarity and dissimilarity of the neuronal response properties in different layers of motor cortex. By conducting electrophysiological recordings in slice preparation, we report the phase response curves of neurons in different cortical layers to demonstrate their layer-dependent synchronization properties. We then study how motor cortex recruits task-related neurons in different layers for voluntary arm movements by simultaneous juxtacellular and multiunit recordings from behaving rats. The results suggest an interesting difference in the spectrum of functional activity between the superficial and deep layers. Furthermore, the task-related activities recorded from various layers exhibited power law distributions of inter-spike intervals (ISIs, in contrast to a general belief that ISIs obey Poisson or Gamma distributions in cortical neurons. We present a theoretical argument that this power law of in vivo neurons may represent the maximization of the entropy of firing rate with limited energy consumption of spike generation. Though further studies are required to fully clarify the functional implications of this coding principle, it may shed new light on information representations by neurons and circuits in motor cortex.
Morphological evidence for local microcircuits in rat vestibular maculae
Ross, M. D.
1997-01-01
Previous studies suggested that intramacular, unmyelinated segments of vestibular afferent nerve fibers and their large afferent endings (calyces) on type I hair cells branch. Many of the branches (processes) contain vesicles and are presynaptic to type II hair cells, other processes, intramacular nerve fibers, and calyces. This study used serial section transmission electron microscopy and three-dimensional reconstruction methods to document the origins and distributions of presynaptic processes of afferents in the medial part of the adult rat utricular macula. The ultrastructural research focused on presynaptic processes whose origin and termination could be observed in a single micrograph. Results showed that calyces had 1) vesiculated, spine-like processes that invaginated type I cells and 2) other, elongate processes that ended on type II cells pre- as well as postsynaptically. Intramacular, unmyelinated segments of afferent nerve fibers gave origin to branches that were presynaptic to type II cells, calyces, calyceal processes, and other nerve fibers in the macula. Synapses with type II cells occurred opposite subsynaptic cisternae (C synapses); all other synapses were asymmetric. Vesicles were pleomorphic but were differentially distributed according to process origin. Small, clear-centered vesicles, approximately 40-60 nm in diameter, predominated in processes originating from afferent nerve fibers and basal parts of calyces. Larger vesicles approximately 70-120 nm in diameter having approximately 40-80 nm electron-opaque cores were dominant in processes originating from the necks of calyces. Results are interpreted to indicate the existence of a complex system of intrinsic feedforward (postsynaptic)-feedback (presynaptic) connections in a network of direct and local microcircuits. The morphological findings support the concept that maculae dynamically preprocess linear acceleratory information before its transmission to the central nervous system.
Magneto switch microcircuit and wind speed measurement’s sensor on its base
Directory of Open Access Journals (Sweden)
Kasimov F. D.
2009-04-01
Full Text Available The magneto switch microcircuit on the base of Hall-effect is developed. The electric scheme of the magneto sensitive IC was designed and its basic technical characteristics are described. The gauge of wind speed on its base is fabricated.
Sitaraman, Divya; Aso, Yoshinori; Jin, Xin; Chen, Nan; Felix, Mario; Rubin, Gerald M; Nitabach, Michael N
2015-11-16
The Drosophila mushroom body (MB) is a key associative memory center that has also been implicated in the control of sleep. However, the identity of MB neurons underlying homeostatic sleep regulation, as well as the types of sleep signals generated by specific classes of MB neurons, has remained poorly understood. We recently identified two MB output neuron (MBON) classes whose axons convey sleep control signals from the MB to converge in the same downstream target region: a cholinergic sleep-promoting MBON class and a glutamatergic wake-promoting MBON class. Here, we deploy a combination of neurogenetic, behavioral, and physiological approaches to identify and mechanistically dissect sleep-controlling circuits of the MB. Our studies reveal the existence of two segregated excitatory synaptic microcircuits that propagate homeostatic sleep information from different populations of intrinsic MB "Kenyon cells" (KCs) to specific sleep-regulating MBONs: sleep-promoting KCs increase sleep by preferentially activating the cholinergic MBONs, while wake-promoting KCs decrease sleep by preferentially activating the glutamatergic MBONs. Importantly, activity of the sleep-promoting MB microcircuit is increased by sleep deprivation and is necessary for homeostatic rebound sleep (i.e., the increased sleep that occurs after, and in compensation for, sleep lost during deprivation). These studies reveal for the first time specific functional connections between subsets of KCs and particular MBONs and establish the identity of synaptic microcircuits underlying transmission of homeostatic sleep signals in the MB.
Directory of Open Access Journals (Sweden)
Tengfei Zhang
2015-12-01
Full Text Available With the rapid development of the micro-grid associated with new and clean energies, the smooth switching between grid-connected and islanded operation modes of the micro-grid is a key issue that needs to be addressed urgently. In traditional solutions, V/f (Voltage/frequency control is adopted for the master micro sources when the micro-grid works in islanded mode, while PQ (real and reactive power control is adopted when in grid-connected mode. However, when the two controllers switch when mode transfer occurs, transient oscillations usually occur and thereafter the dynamic response will be degraded. This paper considers an archetypical micro-grid with Wind-PV-ES (Wind, Photovoltaic and Energy Storage hybrid system, which forms the basis of our case study. The underlying reason for such transient oscillation is analyzed in this paper. Thereafter a modified control strategy for seamless mode transfer is designed and implemented. An improved PQ control method is designed by which the output of the PQ controller always synchronously tracks the output of the V/f controller for micro-grid switches from islanded mode to grid-connected; furthermore, a dq rotating coordinate synchronization based V/f control method is proposed for transition from grid-connected mode to islanded mode. Finally, experiments and analysis are undertaken on some basic and important operating cases; the results in our case study indicate that the modified control strategy is effective in dominating the micro-grid during mode transfer and thus yielding significantly better performances.
Daszyńska-Daszkiewicz, J.; Pamyatnykh, A. A.; Walczak, P.; Colgan, J.; Fontes, C. J.; Kilcrease, D. P.
2017-04-01
The analysis of the BRIght Target Explorer (BRITE) oscillation spectrum of the main-sequence early B-type star ν Eridani is presented. Only models with the modified mean opacity profile can account for the observed frequency ranges as well as for the values of some individual frequencies. The number of the κ-modified seismic models is constrained by the non-adiabatic parameter f, which is very sensitive to the opacity changes in the subphotospheric layers, where the pulsations are driven. We present an example of the model that satisfies all the above conditions. It seems that the OPLIB opacities are preferred over those from the OPAL and OP projects. Moreover, we discuss additional consequences of the opacity modification, namely, an enhancement of the efficiency of convection in the Z bump as well as an occurrence of close radial modes which is a kind of avoided-crossing phenomenon common for non-radial modes in standard main-sequence models.
Di Lazzaro, Vincenzo; Ziemann, Ulf
2013-01-01
Although transcranial magnetic stimulation (TMS) activates a number of different neuron types in the cortex, the final output elicited in corticospinal neurones is surprisingly stereotyped. A single TMS pulse evokes a series of descending corticospinal volleys that are separated from each other by about 1.5 ms (i.e., ~670 Hz). This evoked descending corticospinal activity can be directly recorded by an epidural electrode placed over the high cervical cord. The earliest wave is thought to originate from the direct activation of the axons of fast-conducting pyramidal tract neurones (PTN) and is therefore termed "D" wave. The later waves are thought to originate from indirect, trans-synaptic activation of PTNs and are termed "I" waves. The anatomical and computational characteristics of a canonical microcircuit model of cerebral cortex composed of layer II and III and layer V excitatory pyramidal cells, inhibitory interneurons, and cortico-cortical and thalamo-cortical inputs can account for the main characteristics of the corticospinal activity evoked by TMS including its regular and rhythmic nature, the stimulus intensity-dependence and its pharmacological modulation. In this review we summarize present knowledge of the physiological basis of the effects of TMS of the human motor cortex describing possible interactions between TMS and simple canonical microcircuits of neocortex. According to the canonical model, a TMS pulse induces strong depolarization of the excitatory cells in the superficial layers of the circuit. This leads to highly synchronized recruitment of clusters of excitatory neurons, including layer V PTNs, and of inhibitory interneurons producing a high frequency (~670 Hz) repetitive discharge of the corticospinal axons. The role of the inhibitory circuits is crucial to entrain the firing of the excitatory networks to produce a high-frequency discharge and to control the number and magnitude of evoked excitatory discharge in layer V PTNs. In summary
Obtaining raised density connections by thermosonic microwelding in 3D integrated microcircuits
Directory of Open Access Journals (Sweden)
Lanin V. L.
2014-06-01
Full Text Available The authors consider the processes of obtaining raised density microwelded connections in 3D-integrated microcircuits by the thermosonic microwelding. The processes include the use of the raised frequencies of ultrasound, application of the microinstrument with a thinning of the working end and precision devices for ball formation, which provide reproducibility of connections quality. At a small step of contact pads, the use of a wire of small diameter (not more than 25 µm is necessary for devices with a multilevel arrangement of leads and chess arrangement of contact pads on the chip, providing the maximum length of the formed crosspieces does not exceed 4—5 mm.
Modeling the Cerebellar Microcircuit: New Strategies for a Long-Standing Issue
D’Angelo, Egidio; Antonietti, Alberto; Casali, Stefano; Casellato, Claudia; Garrido, Jesus A.; Luque, Niceto Rafael; Mapelli, Lisa; Masoli, Stefano; Pedrocchi, Alessandra; Prestori, Francesca; Rizza, Martina Francesca; Ros, Eduardo
2016-01-01
The cerebellar microcircuit has been the work bench for theoretical and computational modeling since the beginning of neuroscientific research. The regular neural architecture of the cerebellum inspired different solutions to the long-standing issue of how its circuitry could control motor learning and coordination. Originally, the cerebellar network was modeled using a statistical-topological approach that was later extended by considering the geometrical organization of local microcircuits. However, with the advancement in anatomical and physiological investigations, new discoveries have revealed an unexpected richness of connections, neuronal dynamics and plasticity, calling for a change in modeling strategies, so as to include the multitude of elementary aspects of the network into an integrated and easily updatable computational framework. Recently, biophysically accurate “realistic” models using a bottom-up strategy accounted for both detailed connectivity and neuronal non-linear membrane dynamics. In this perspective review, we will consider the state of the art and discuss how these initial efforts could be further improved. Moreover, we will consider how embodied neurorobotic models including spiking cerebellar networks could help explaining the role and interplay of distributed forms of plasticity. We envisage that realistic modeling, combined with closed-loop simulations, will help to capture the essence of cerebellar computations and could eventually be applied to neurological diseases and neurorobotic control systems. PMID:27458345
Directory of Open Access Journals (Sweden)
Frank Klefenz
2013-01-01
Full Text Available A computational model of a self-structuring neuronal net is presented in which repetitively applied pattern sets induce the formation of cortical columns and microcircuits which decode distinct patterns after a learning phase. In a case study, it is demonstrated how specific neurons in a feature classifier layer become orientation selective if they receive bar patterns of different slopes from an input layer. The input layer is mapped and intertwined by self-evolving neuronal microcircuits to the feature classifier layer. In this topical overview, several models are discussed which indicate that the net formation converges in its functionality to a mathematical transform which maps the input pattern space to a feature representing output space. The self-learning of the mathematical transform is discussed and its implications are interpreted. Model assumptions are deduced which serve as a guide to apply model derived repetitive stimuli pattern sets to in vitro cultures of neuron ensembles to condition them to learn and execute a mathematical transform.
Directory of Open Access Journals (Sweden)
Athanasia Papoutsi
2014-07-01
Full Text Available Technological advances have unraveled the existence of small clusters of co-active neurons in the neocortex. The functional implications of these microcircuits are in large part unexplored. Using a heavily constrained biophysical model of a L5 PFC microcircuit, we recently showed that these structures act as tunable modules of persistent activity, the cellular correlate of working memory. Here, we investigate the mechanisms that underlie persistent activity emergence (ON and termination (OFF and search for the minimum network size required for expressing these states within physiological regimes. We show that (a NMDA-mediated dendritic spikes gate the induction of persistent firing in the microcircuit. (b The minimum network size required for persistent activity induction is inversely proportional to the synaptic drive of each excitatory neuron. (c Relaxation of connectivity and synaptic delay constraints eliminates the gating effect of NMDA spikes, albeit at a cost of much larger networks. (d Persistent activity termination by increased inhibition depends on the strength of the synaptic input and is negatively modulated by dADP. (e Slow synaptic mechanisms and network activity contain predictive information regarding the ability of a given stimulus to turn ON and/or OFF persistent firing in the microcircuit model. Overall, this study zooms out from dendrites to cell assemblies and suggests a tight interaction between dendritic non-linearities and network properties (size/connectivity that may facilitate the short-memory function of the PFC.
Packer, Adam M; Yuste, Rafael
2011-09-14
GABAergic interneurons play a major role in the function of the mammalian neocortex, but their circuit connectivity is still poorly understood. We used two-photon RuBi-Glutamate uncaging to optically map how the largest population of cortical interneurons, the parvalbumin-positive cells (PV+), are connected to pyramidal cells (PCs) in mouse neocortex. We found locally dense connectivity from PV+ interneurons onto PCs across cortical areas and layers. In many experiments, all nearby PV+ cells were connected to every local PC sampled. In agreement with this, we found no evidence for connection specificity, as PV+ interneurons contacted PC pairs similarly regardless of whether they were synaptically connected or not. We conclude that the microcircuit architecture for PV+ interneurons, and probably neocortical inhibition in general, is an unspecific, densely homogenous matrix covering all nearby pyramidal cells.
Song, Chen; Zhang, Wen-Hua; Wang, Xue-Hui; Zhang, Jun-Yu; Tian, Xiao-Li; Yin, Xiao-Ping; Pan, Bing-Xing
2017-01-09
Amygdala activation is known to be critical for the processing of stressful events in brain. Recent studies have shown that the projection neurons (PNs) in amygdala, although architecturally intermingled, are integrated into distinct microcircuits and thus play divergent roles in amygdala-related behaviors. It remains unknown how stress regulates the individual amygdala PNs embedded in distinct microcircuits. Here, by using retrograde tracing and electrophysiological recording in in vitro slices, we explored the modulation of acute immobilization stress (AIS) on the basoamygdala (BA) PNs projecting either to medial prefrontal cortex (mPFC) or elsewhere, which we designated as BA-mPFC and non-BA-mPFC PNs respectively. The results showed that in the control mice, both the excitatory and inhibitory postsynaptic currents (sEPSCs/sIPSCs) were comparable between these two subsets of BA PNs. The influences of AIS on sEPSCs and sIPSCs were overall similar between the two neuronal populations. It markedly increased the sEPSCs amplitude but left unaltered their frequency as well as the sIPSCs amplitude and frequency. Despite this, several differences emerged between the effects of AIS on the distribution of sEPSCs/sIPSCs frequency in these two groups of BA PNs. Similar changes were also observed in the sEPSCs/sIPSCs of the two PN populations from mice experiencing forced swimming stress. Their intrinsic excitability, on the other hand, was nearly unaltered following AIS. Our results thus suggest that acute stress recruit both BA-mPFC and non-BA-mPFC PNs mainly through enhancing the glutamatergic transmission they receive.
Encoding and retrieval in a model of the hippocampal CA1 microcircuit.
Cutsuridis, Vassilis; Cobb, Stuart; Graham, Bruce P
2010-03-01
It has been proposed that the hippocampal theta rhythm (4-7 Hz) can contribute to memory formation by separating encoding (storage) and retrieval of memories into different functional half-cycles (Hasselmo et al. (2002) Neural Comput 14:793-817). We investigate, via computer simulations, the biophysical mechanisms by which storage and recall of spatio-temporal input patterns are achieved by the CA1 microcircuitry. A model of the CA1 microcircuit is presented that uses biophysical representations of the major cell types, including pyramidal (P) cells and four types of inhibitory interneurons: basket (B) cells, axo-axonic (AA) cells, bistratified (BS) cells and oriens lacunosum-moleculare (OLM) cells. Inputs to the network come from the entorhinal cortex (EC), the CA3 Schaffer collaterals and medial septum. The EC input provides the sensory information, whereas all other inputs provide context and timing information. Septal input provides timing information for phasing storage and recall. Storage is accomplished via a local STDP mediated hetero-association of the EC input pattern and the incoming CA3 input pattern on the CA1 pyramidal cell target synapses. The model simulates the timing of firing of different hippocampal cell types relative to the theta rhythm in anesthetized animals and proposes experimentally confirmed functional roles for the different classes of inhibitory interneurons in the storage and recall cycles (Klausberger et al., (2003, 2004) Nature 421:844-848, Nat Neurosci 7:41-47). Measures of recall performance of new and previously stored input patterns in the presence or absence of various inhibitory interneurons are employed to quantitatively test the performance of our model. Finally, the mean recall quality of the CA1 microcircuit is tested as the number of stored patterns is increased.
Directory of Open Access Journals (Sweden)
Athanasia Papoutsi
2014-03-01
Full Text Available The ways in which neurons are embedded in a network to support various computations determines the functional output of the cortex. Recently, a number of in vivo studies have shown that dendritic integration in pyramidal neurons shapes neuronal function (Smith et al., 2013; Longordo et al., 2013 and that clusters of few reciprocally connected neurons are co-activated during behavioral tasks (Ko et al., 2011, 2013; Morishima et al., 2011. In the prefrontal cortex (PFC, such microcircuits are linked to persistent activity (prolonged spiking activity that exceeds stimulus presentation, which is the cellular correlate of working memory (Papoutsi et al., 2013. However, the effect of dendritic integration on the functional output of such small microcircuits has remained unexplored. In this work, we investigate the contribution of nonlinear dendritic properties to the induction and coding of upcoming state transitions in PFC microcircuits. Towards this goal we used a heavily constrained biophysical model of a layer 5 PFC microcircuit consisting of 7 pyramidal neurons and 2 interneurons implemented in the NEURON simulation environment. All neuron models are biophysically detailed but morphologically simplified and validated regarding their intrinsic, synaptic and connectivity properties (Papoutsi et al., 2013. Our results show that the non-linear integration of synaptic inputs at the basal dendrites of pyramidal neurons, mediated by the induction of NMDA spikes, is imperative for the emergence of the persistent state in the microcircuit: if synaptic drive is sufficient to induce NMDA spikes, the minimum network size required for persistent activity induction can be reduced down to 2 cells. In addition, slow synaptic mechanisms, such as the NMDA and GABAB currents, determine the ability of a given stimulus to induce persistent firing in the microcircuit model. On the other hand, the necessity for NMDA spikes disappears when persistent activity depends on
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.
Energy Technology Data Exchange (ETDEWEB)
Atakishiyev, N.M. [Instituto de Matematicas. Universidad Nacional Autonoma de Mexico. Cuernavaca, Morelos (Mexico); Jafarov, E.I.; Nagiyev, S.M. [Institute of Physics, Azerbaijan Academy of Sciences. Baku, Azerbaijan (Azerbaijan); Wolf, K.B. [Instituto de Investigaciones en Matematicas Aplicadas y en Sistemas. Universidad Nacional Autonoma de Mexico. Cuernavaca, Morelos (Mexico)
1998-10-01
Meixner oscillators have a ground state and an energy spectrum that is equally spaced; they are a two-parameter family of models that satisfy a Hamiltonian equation with a difference operator. Meixner oscillators include as limits and particular cases the Charlier, Kravchuk and Hermite (common quantum-mechanical) harmonic oscillators. By the Sommerfeld-Watson transformation they are also related with a relativistic model of the linear harmonic oscillator, built in terms of the Meixner-Pollaczek polynomials, and their continuous weight function. We construct explicitly the corresponding coherent states with the dynamical symmetry group Sp(2,R). The reproducing kernel for the wavefunctions of these models is also found. (Author)
Li, Fenfang; Nguyen, Dang Minh; Ohl, Claus-Dieter
2016-01-01
We report about an intriguing boiling regime occurring for small heaters embedded on the boundary in subcooled water. The microheater is realized by focusing a continuous wave laser beam to about $10\\,\\mu$m in diameter onto a 165\\,nm-thick layer of gold, which is submerged in water. After an initial vaporous explosion a single bubble oscillates continuously and repeatably at several $100\\,$kHz. The microbubble's oscillations are accompanied with bubble pinch-off leading to a stream of gaseous bubbles into the subcooled water. The self-driven bubble oscillation is explained with a thermally kicked oscillator caused by the non-spherical collapses and by surface pinning. Additionally, Marangoni stresses induce a recirculating streaming flow which transports cold liquid towards the microheater reducing diffusion of heat along the substrate and therefore stabilizing the phenomenon to many million cycles. We speculate that this oscillate boiling regime may allow to overcome the heat transfer thresholds observed dur...
Nogo Receptor 1 Confines a Disinhibitory Microcircuit to the Critical Period in Visual Cortex.
Stephany, Céleste-Élise; Ikrar, Taruna; Nguyen, Collins; Xu, Xiangmin; McGee, Aaron W
2016-10-26
A characteristic of the developing mammalian visual system is a brief interval of plasticity, termed the "critical period," when the circuitry of primary visual cortex is most sensitive to perturbation of visual experience. Depriving one eye of vision (monocular deprivation [MD]) during the critical period alters ocular dominance (OD) by shifting the responsiveness of neurons in visual cortex to favor the nondeprived eye. A disinhibitory microcircuit involving parvalbumin-expressing (PV) interneurons initiates this OD plasticity. The gene encoding the neuronal nogo-66-receptor 1 (ngr1/rtn4r) is required to close the critical period. Here we combined mouse genetics, electrophysiology, and circuit mapping with laser-scanning photostimulation to investigate whether disinhibition is confined to the critical period by ngr1 We demonstrate that ngr1 mutant mice retain plasticity characteristic of the critical period as adults, and that ngr1 operates within PV interneurons to restrict the loss of intracortical excitatory synaptic input following MD in adult mice, and this disinhibition induces a "lower PV network configuration" in both critical-period wild-type mice and adult ngr1(-/-) mice. We propose that ngr1 limits disinhibition to close the critical period for OD plasticity and that a decrease in PV expression levels reports the diminished recent cumulative activity of these interneurons.
Self-Organization of Microcircuits in Networks of Spiking Neurons with Plastic Synapses.
Directory of Open Access Journals (Sweden)
Gabriel Koch Ocker
2015-08-01
Full Text Available The synaptic connectivity of cortical networks features an overrepresentation of certain wiring motifs compared to simple random-network models. This structure is shaped, in part, by synaptic plasticity that promotes or suppresses connections between neurons depending on their joint spiking activity. Frequently, theoretical studies focus on how feedforward inputs drive plasticity to create this network structure. We study the complementary scenario of self-organized structure in a recurrent network, with spike timing-dependent plasticity driven by spontaneous dynamics. We develop a self-consistent theory for the evolution of network structure by combining fast spiking covariance with a slow evolution of synaptic weights. Through a finite-size expansion of network dynamics we obtain a low-dimensional set of nonlinear differential equations for the evolution of two-synapse connectivity motifs. With this theory in hand, we explore how the form of the plasticity rule drives the evolution of microcircuits in cortical networks. When potentiation and depression are in approximate balance, synaptic dynamics depend on weighted divergent, convergent, and chain motifs. For additive, Hebbian STDP these motif interactions create instabilities in synaptic dynamics that either promote or suppress the initial network structure. Our work provides a consistent theoretical framework for studying how spiking activity in recurrent networks interacts with synaptic plasticity to determine network structure.
Automatic microcircuit formation based on gold-coated SU-8 microrods via dielectrophoresis
Institute of Scientific and Technical Information of China (English)
Ren Yu-Kun; Tao Ye; Hou Li-Kai; Jiang Hong-Yuan
2013-01-01
To explore the application of the characteristics of metallic microparticles,alternating current electric trapping of the SU-8 microrods coated with a thin gold layer by the chemical approach is investigated.Positive dielectrophoresis is used to absorb the gold-coated SU-8 microrods at the edge of the parallel electrodes,thereby forming chains to connect the electrodes.This is a fast automatic microcircuit formation process.Moreover,a non-charged molecule is modified on the surface of the gold-coated SU-8 microrod,and the modified microrods are controlled by the alternating electric field to form a number of chains.The different chains between the parallel electrodes consist of various parallel circuits.In order to compare these chains with different electric surfaces,the impedances of the metallic and modified microrods are measured and compared,and the results show that the gold-coated microrods act as pure resistors,while the microrods functionalized by a non-charged molecule behave as good capacitors.
Self-Organization of Microcircuits in Networks of Spiking Neurons with Plastic Synapses.
Ocker, Gabriel Koch; Litwin-Kumar, Ashok; Doiron, Brent
2015-08-01
The synaptic connectivity of cortical networks features an overrepresentation of certain wiring motifs compared to simple random-network models. This structure is shaped, in part, by synaptic plasticity that promotes or suppresses connections between neurons depending on their joint spiking activity. Frequently, theoretical studies focus on how feedforward inputs drive plasticity to create this network structure. We study the complementary scenario of self-organized structure in a recurrent network, with spike timing-dependent plasticity driven by spontaneous dynamics. We develop a self-consistent theory for the evolution of network structure by combining fast spiking covariance with a slow evolution of synaptic weights. Through a finite-size expansion of network dynamics we obtain a low-dimensional set of nonlinear differential equations for the evolution of two-synapse connectivity motifs. With this theory in hand, we explore how the form of the plasticity rule drives the evolution of microcircuits in cortical networks. When potentiation and depression are in approximate balance, synaptic dynamics depend on weighted divergent, convergent, and chain motifs. For additive, Hebbian STDP these motif interactions create instabilities in synaptic dynamics that either promote or suppress the initial network structure. Our work provides a consistent theoretical framework for studying how spiking activity in recurrent networks interacts with synaptic plasticity to determine network structure.
Falsifying Oscillation Properties of Parametric Biological Models
Directory of Open Access Journals (Sweden)
Thao Dang
2013-08-01
Full Text Available We propose an approach to falsification of oscillation properties of parametric biological models, based on the recently developed techniques for testing continuous and hybrid systems. In this approach, an oscillation property can be specified using a hybrid automaton, which is then used to guide the exploration in the state and input spaces to search for the behaviors that do not satisfy the property. We illustrate the approach with the Laub-Loomis model for spontaneous oscillations during the aggregation stage of Dictyostelium.
Kuznetsov, N. V.; Popov, V. D.; Khamidullina, N. M.
2005-05-01
When designing the radio-electronic equipment for long-term operation in a space environment, one of the most important problems is a correct estimation of radiation stability of its electric and radio components (ERC) against radiation-stimulated doze failures and one-particle effects (upsets). These problems are solved in this paper for the integrated microcircuits (IMC) of various types that are to be installed onboard the Fobos-Grunt spacecraft designed at the Federal State Unitary Enterprise “Lavochkin Research and Production Association.” The launching of this spacecraft is planned for 2009.
Oscillation death in coupled oscillators
Institute of Scientific and Technical Information of China (English)
Wei ZOU; Xin-gang WANG; Qi ZHAO; Meng ZHAN
2009-01-01
We study dynamical behaviors in coupled nonlinear oscillators and find that under certain condi- tions, a whole coupled oscillator system can cease oscil- lation and transfer to a globally nonuniform stationary state [I.e., the so-called oscillation death (OD) state], and this phenomenon can be generally observed. This OD state depends on coupling strengths and is clearly differ- ent from previously studied amplitude death (AD) state, which refers to the phenomenon where the whole system is trapped into homogeneously steady state of a fixed point, which already exists but is unstable in the ab- sence of coupling. For larger systems, very rich pattern structures of global death states are observed. These Turing-like patterns may share some essential features with the classical Turing pattern.
Carrillo-Reid, Luis; Hernández-López, Salvador; Tapia, Dagoberto; Galarraga, Elvira; Bargas, José
2011-10-19
Selection and inhibition of motor behaviors are related to the coordinated activity and compositional capabilities of striatal cell assemblies. Striatal network activity represents a main step in basal ganglia processing. The dopaminergic system differentially regulates distinct populations of striatal medium spiny neurons (MSNs) through the activation of D(1)- or D(2)-type receptors. Although postsynaptic and presynaptic actions of these receptors are clearly different in MSNs during cell-focused studies, their activation during network activity has shown inconsistent responses. Therefore, using electrophysiological techniques, functional multicell calcium imaging, and neuronal population analysis in rat corticostriatal slices, we describe the effect of selective dopaminergic receptor activation in the striatal network by observing cell assembly configurations. At the microcircuit level, during striatal network activity, the selective activation of either D(1)- or D(2)-type receptors is reflected as overall increases in neuronal synchronization. However, graph theory techniques applied to the transitions between network states revealed receptor-specific configurations of striatal cell assemblies: D(1) receptor activation generated closed trajectories with high recurrence and few alternate routes favoring the selection of specific sequences, whereas D(2) receptor activation created trajectories with low recurrence and more alternate pathways while promoting diverse transitions among neuronal pools. At the single-cell level, the activation of dopaminergic receptors enhanced the negative-slope conductance region (NSCR) in D(1)-type-responsive cells, whereas in neurons expressing D(2)-type receptors, the NSCR was decreased. Consequently, receptor-specific network dynamics most probably result from the interplay of postsynaptic and presynaptic dopaminergic actions.
Directory of Open Access Journals (Sweden)
G. Bellini
2014-01-01
Full Text Available In the last decades, a very important breakthrough has been brought about in the elementary particle physics by the discovery of the phenomenon of the neutrino oscillations, which has shown neutrino properties beyond the Standard Model. But a full understanding of the various aspects of the neutrino oscillations is far to be achieved. In this paper the theoretical background of the neutrino oscillation phenomenon is described, referring in particular to the paradigmatic models. Then the various techniques and detectors which studied neutrinos from different sources are discussed, starting from the pioneering ones up to the detectors still in operation and to those in preparation. The physics results are finally presented adopting the same research path which has been crossed by this long saga. The problems not yet fixed in this field are discussed, together with the perspectives of their solutions in the near future.
Nayfeh, Ali Hasan
1995-01-01
Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim
Freire, Joana G.; Cabeza, Cecilia; Marti, Arturo; Pöschel, Thorsten; Gallas, Jason A. C.
2013-06-01
The investigation of regular and irregular patterns in nonlinear oscillators is an outstanding problem in physics and in all natural sciences. In general, regularity is understood as tantamount to periodicity. However, there is now a flurry of works proving the existence of ``antiperiodicity'', an unfamiliar type of regularity. Here we report the experimental observation and numerical corroboration of antiperiodic oscillations. In contrast to the isolated solutions presently known, we report infinite hierarchies of antiperiodic waveforms that can be tuned continuously and that form wide spiral-shaped stability phases in the control parameter plane. The waveform complexity increases towards the focal point common to all spirals, a key hub interconnecting them all.
Nurmikko, Arto V.; Donoghue, John P.; Hochberg, Leigh R.; Patterson, William R.; Song, Yoon-Kyu; Bull, Christopher W.; Borton, David A.; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan
2011-01-01
Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature’s amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic “brain-interfaces” within the body, a point of special emphasis of this paper. PMID:21654935
Power oscillation damping controller
DEFF Research Database (Denmark)
2012-01-01
A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...
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.
DEFF Research Database (Denmark)
Lindberg, Erik
1997-01-01
In order to obtain insight in the nature of nonlinear oscillators the eigenvalues of the linearized Jacobian of the differential equations describing the oscillator are found and displayed as functions of time. A number of oscillators are studied including Dewey's oscillator (piecewise linear...... with negative resistance), Kennedy's Colpitts-oscillator (with and without chaos) and a new 4'th order oscillator with hyper-chaos....
Oscillating Permanent Magnets.
Michaelis, M. M.; Haines, C. M.
1989-01-01
Describes several ways to partially levitate permanent magnets. Computes field line geometries and oscillation frequencies. Provides several diagrams illustrating the mechanism of the oscillation. (YP)
Solar neutrinos: Oscillations or No-oscillations?
Smirnov, A Yu
2016-01-01
The Nobel prize in physics 2015 has been awarded "... for the discovery of neutrino oscillations which show that neutrinos have mass". While SuperKamiokande (SK), indeed, has discovered oscillations, SNO observed effect of the adiabatic (almost non-oscillatory) flavor conversion of neutrinos in the matter of the Sun. Oscillations are irrelevant for solar neutrinos apart from small $\
Oscillations of Eccentric Pulsons
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Groenbech-Jensen, Niels; Lomdahl, Peter;
1997-01-01
Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct.......Perturbation theory for elliptic pulsons is developed and predicts pulson and eccentricity oscillations. The pulson oscillation period is predicted qualitatively correct....
Energy Technology Data Exchange (ETDEWEB)
Skinner, F. K. [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada); Department of Medicine (Neurology), University of Toronto, 200 Elizabeth Street, Toronto, Ontario M5G 2C4 (Canada); Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King' s College Circle, Toronto, Ontario M5S 1A8 (Canada); Ferguson, K. A. [Toronto Western Research Institute, University Health Network, Krembil Discovery Tower, Toronto Western Hospital, 60 Leonard Street, 7th floor, 7KD411, Toronto, Ontario M5T 2S8 (Canada); Department of Physiology, University of Toronto Medical Sciences Building, 3rd Floor, 1 King' s College Circle, Toronto, Ontario M5S 1A8 (Canada)
2013-12-15
There is an undisputed need and requirement for theoretical and computational studies in Neuroscience today. Furthermore, it is clear that oscillatory dynamical output from brain networks is representative of various behavioural states, and it is becoming clear that one could consider these outputs as measures of normal and pathological brain states. Although mathematical modeling of oscillatory dynamics in the context of neurological disease exists, it is a highly challenging endeavour because of the many levels of organization in the nervous system. This challenge is coupled with the increasing knowledge of cellular specificity and network dysfunction that is associated with disease. Recently, whole hippocampus in vitro preparations from control animals have been shown to spontaneously express oscillatory activities. In addition, when using preparations derived from animal models of disease, these activities show particular alterations. These preparations present an opportunity to address challenges involved with using models to gain insight because of easier access to simultaneous cellular and network measurements, and pharmacological modulations. We propose that by developing and using models with direct links to experiment at multiple levels, which at least include cellular and microcircuit, a cycling can be set up and used to help us determine critical mechanisms underlying neurological disease. We illustrate our proposal using our previously developed inhibitory network models in the context of these whole hippocampus preparations and show the importance of having direct links at multiple levels.
Li, Fei-Ye; Luo, Xi; Dai, Xi; Yu, Yue; Zhang, Fan; Chen, Gang
2016-09-01
We construct a tight-binding model realizing one pair of Weyl nodes and three distinct Weyl semimetals. In the type-I (type-II) Weyl semimetal, both nodes belong to type-I (type-II) Weyl nodes. In addition, there exists a third type, previously undiscovered and dubbed "hybrid Weyl semimetal", in which one Weyl node is of type I while the other is of type II. For the hybrid Weyl semimetal, we further demonstrate the bulk Fermi surfaces and the topologically protected surface states, analyze the unique Landau-level structure and quantum oscillation, and discuss the conditions for possible material realization.
The Dynamics of a Periodically Forced Cortical Microcircuit, With an Application to Schizophrenia
Vierling-Claassen, Dorea; Kopell, Nancy
2009-01-01
Synchronous neural activity in the brain in the gamma and beta frequency bands (50-70 Hz)is thought to be important for sensory processing and is altered in schizophrenia. In a previous study, gamma/beta click-train auditory stimuli were used to probe cortical oscillatory activity in control and schizophrenic subjects. We found that control subjects exhibited preferential 40 Hz responses to both 20 and 40 Hz stimulations, while schizophrenic subjects had enhanced 20 Hz responses to the same stimuli [D. Vierling-Claassen, P. Siekmeier, S. Stufflebeam, and N. Kopell, J. Neurophysiol., 99 (2008), p. 2656]. High-dimensional computational network models constructed previously, which were based on evidence of altered inhibition in schizophrenia, numerically generated the entrainment behaviors observed experimentally. However, questions regarding the dynamic origin of model behaviors remained. It was not clear that the 20 Hz response to 40 Hz drive in the schizophrenic network was robust to parameter changes, which would be necessary for the predicted mechanism to explain data from a heterogeneous subject population. In the schizophrenic network we observed 30 Hz drive responses with a frequency component below 30 Hz, for which no analogue appeared in experimental data, and wondered if these were dynamically distinct from the modeled 20 Hz response to 40 Hz drive. We also wished to explore the role of background noise in model behavior. To address these questions, we consider a system of two mutually coupled oscillators representative of neural cells, driven periodically in the gamma/beta frequency band. We show that there is a one-parameter family of discontinuous discrete maps, whose dynamics clarifies issues of robustness, classifies entrainment patterns, and provides insight into the role of excitatory noise.
Directory of Open Access Journals (Sweden)
Sooyun Kim
Full Text Available Oriens-lacunosum moleculare (O-LM interneurons in the CA1 region of the hippocampus play a key role in feedback inhibition and in the control of network activity. However, how these cells are efficiently activated in the network remains unclear. To address this question, I performed recordings from CA1 pyramidal neuron axons, the presynaptic fibers that provide feedback innervation of these interneurons. Two forms of axonal action potential (AP modulation were identified. First, repetitive stimulation resulted in activity-dependent AP broadening. Broadening showed fast onset, with marked changes in AP shape following a single AP. Second, tonic depolarization in CA1 pyramidal neuron somata induced AP broadening in the axon, and depolarization-induced broadening summated with activity-dependent broadening. Outside-out patch recordings from CA1 pyramidal neuron axons revealed a high density of α-dendrotoxin (α-DTX-sensitive, inactivating K+ channels, suggesting that K+ channel inactivation mechanistically contributes to AP broadening. To examine the functional consequences of axonal AP modulation for synaptic transmission, I performed paired recordings between synaptically connected CA1 pyramidal neurons and O-LM interneurons. CA1 pyramidal neuron-O-LM interneuron excitatory postsynaptic currents (EPSCs showed facilitation during both repetitive stimulation and tonic depolarization of the presynaptic neuron. Both effects were mimicked and occluded by α-DTX, suggesting that they were mediated by K+ channel inactivation. Therefore, axonal AP modulation can greatly facilitate the activation of O-LM interneurons. In conclusion, modulation of AP shape in CA1 pyramidal neuron axons substantially enhances the efficacy of principal neuron-interneuron synapses, promoting the activation of O-LM interneurons in recurrent inhibitory microcircuits.
Kim, Sooyun
2014-01-01
Oriens-lacunosum moleculare (O-LM) interneurons in the CA1 region of the hippocampus play a key role in feedback inhibition and in the control of network activity. However, how these cells are efficiently activated in the network remains unclear. To address this question, I performed recordings from CA1 pyramidal neuron axons, the presynaptic fibers that provide feedback innervation of these interneurons. Two forms of axonal action potential (AP) modulation were identified. First, repetitive stimulation resulted in activity-dependent AP broadening. Broadening showed fast onset, with marked changes in AP shape following a single AP. Second, tonic depolarization in CA1 pyramidal neuron somata induced AP broadening in the axon, and depolarization-induced broadening summated with activity-dependent broadening. Outside-out patch recordings from CA1 pyramidal neuron axons revealed a high density of α-dendrotoxin (α-DTX)-sensitive, inactivating K+ channels, suggesting that K+ channel inactivation mechanistically contributes to AP broadening. To examine the functional consequences of axonal AP modulation for synaptic transmission, I performed paired recordings between synaptically connected CA1 pyramidal neurons and O-LM interneurons. CA1 pyramidal neuron-O-LM interneuron excitatory postsynaptic currents (EPSCs) showed facilitation during both repetitive stimulation and tonic depolarization of the presynaptic neuron. Both effects were mimicked and occluded by α-DTX, suggesting that they were mediated by K+ channel inactivation. Therefore, axonal AP modulation can greatly facilitate the activation of O-LM interneurons. In conclusion, modulation of AP shape in CA1 pyramidal neuron axons substantially enhances the efficacy of principal neuron-interneuron synapses, promoting the activation of O-LM interneurons in recurrent inhibitory microcircuits.
Berghuis, Paul; Dobszay, Marton B; Sousa, Kyle M; Schulte, Gunnar; Mager, Peter P; Härtig, Wolfgang; Görcs, Tamás J; Zilberter, Yuri; Ernfors, Patrik; Harkany, Tibor
2004-09-01
GABAergic interneurons with high-frequency firing, fast-spiking (FS) cells, form synapses on perisomatic regions of principal cells in the neocortex and hippocampus to control the excitability of cortical networks. Brain-derived neurotrophic factor (BDNF) is essential for the differentiation of multiple interneuron subtypes and the formation of their synaptic contacts. Here, we examined whether BDNF, alone or in conjunction with sustained KCl-induced depolarization, drives functional FS cell differentiation and the formation of inhibitory microcircuits. Homogeneous FS cell cultures were established by target-specific isolation using the voltage-gated potassium channel 3.1b subunit as the selection marker. Isolated FS cells expressed parvalbumin, were surrounded by perineuronal nets, formed immature inhibitory connections and generated slow action potentials at 12 days in vitro. Brain-derived neurotrophic factor (BDNF) promoted FS cell differentiation by increasing the somatic diameter, dendritic branching and the frequency of action potential firing. In addition, BDNF treatment led to a significant up-regulation of synaptophysin and vesicular GABA transporter expression, components of the synaptic machinery critical for GABA release, which was paralleled by an increase in synaptic strength. Long-term membrane depolarization alone was detrimental to dendritic branching. However, we observed that BDNF and KCl exerted additive effects, as reflected by the significantly accelerated maturation of synaptic contacts and high discharge frequencies, and was required for the formation of reciprocal connections between FS cells. Our results show that BDNF, along with membrane depolarization, is critical for FS cells to establish inhibitory circuitries during corticogenesis.
Pollard, Marie; Bartolome, Jose Manuel; Conn, P Jeffrey; Steckler, Thomas; Shaban, Hamdy
2014-10-01
Suppressing anxiety and fear memory relies on bidirectional projections between the medial prefrontal cortex and the amygdala. Positive allosteric modulators of mGluR5 improve cognition in animal models of schizophrenia and retrieval of newly formed associations such as extinction of fear-conditioned behaviour. The increase in neuronal network activities of the medial prefrontal cortex is influenced by both mGluR1 and mGluR5; however, it is not well understood how they modulate network activities and downstream information processing. To map mGluR5-mediated network activity in relation to its emergence as a viable cognitive enhancer, we tested group I mGluR compounds on medial prefrontal cortex network activity via multi-electrode array neuronal spiking and whole-cell patch clamp recordings. Results indicate that mGluR5 activation promotes feed-forward inhibition that depends on recruitment of neuronal activity by carbachol-evoked up states. The rate of neuronal spiking activity under the influence of carbachol was reduced by the mGluR5 positive allosteric modulator, N-(1,3-Diphenyl-1H-pyrazolo-5-yl)-4-nitrobenzamide (VU-29), and enhanced by the mGluR5 negative allosteric modulator, 3-((2-methyl-1,3-thiazol-4-yl)ethynyl)pyridine hydrochloride (MTEP). Spontaneous inhibitory post-synaptic currents were increased upon application of carbachol and in combination with VU-29. These results emphasize a bias towards tonic mGluR5-mediated inhibition that might serve as a signal-to-noise enhancer of sensory inputs projected from associated limbic areas onto the medial prefrontal cortex neuronal microcircuit.
Ma, Hongbin
2015-01-01
This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation, theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary factors affecting oscillating motions and heat transfer, neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes. The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...
Phenomenology of neutrino oscillations
Indian Academy of Sciences (India)
G Rajasekaran
2000-07-01
The phenomenology of solar, atmospheric, supernova and laboratory neutrino oscillations is described. Analytical formulae for matter effects are reviewed. The results from oscillations are confronted with neutrinoless double beta decay.
Sanin, A.; Semyonov, E.
2012-01-01
Numerical integration of the non-stationary Schrödinger equation with Duffing potential depending on two coordinates has been carried out. Oscillation types and the influence of coupling between two oscillators on frequency spectra are analyzed in detail.
Neutrino Masses and Oscillations
Valle, J W F
2005-01-01
I summarize the status of three--neutrino oscillations that follow from combining the relevant world's data. The discussion includes the small parameters Delta_m-sol/Delta_m-atm and \\sin^2\\theta_{13}, which characterize the strength of CP violation in neutrino oscillations, the impact of oscillation data on the prospects for probing the absolute scale of neutrino mass in \
The colpitts oscillator family
DEFF Research Database (Denmark)
Lindberg, Erik; Murali, K.; Tamasevicius, A.
A tutorial study of the Colpitts oscillator family defined as all oscillators based on a nonlinear amplifier and a three- terminal linear resonance circuit with one coil and two capacitors. The original patents are investigated. The eigenvalues of the linearized Jacobian for oscillators based...
Neutrino oscillations: theory and phenomenology
Energy Technology Data Exchange (ETDEWEB)
Akhmedov, E.K., E-mail: akhmedov@ictp.trieste.it [Department of Theoretical Physics, Royal Institute of Technology, AlbaNova University Center, SE-106 91 Stockholm (Sweden)
2011-12-15
A brief overview of selected topics in the theory and phenomenology of neutrino oscillations is given. These include: oscillations in vacuum and in matter; phenomenology of 3-flavour neutrino oscillations; CP and T violation in neutrino oscillations in vacuum and in matter; matter effects on {nu}{sub {mu}}{r_reversible}{nu}{sub {tau}} oscillations; parametric resonance in neutrino oscillations inside the earth; oscillations below and above the MSW resonance; unsettled issues in the theory of neutrino oscillations.
Covariant harmonic oscillators and coupled harmonic oscillators
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.
Nature's Autonomous Oscillators
Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.
2012-01-01
Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.
A memristor-based third-order oscillator: beyond oscillation
Talukdar, Abdul Hafiz Ibne
2012-10-06
This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.
Kato, Shoji
2016-01-01
This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...
Jenkins, Alejandro
2013-04-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain dynamical systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy into the vibration: no external rate needs to be adjusted to the resonant frequency. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the swaying of the London Millennium Footbridge in 2000. Clocks are self-oscillators, as are bowed and wind musical instruments. The heart is a “relaxation oscillator”, i.e., a non-sinusoidal self-oscillator whose period is determined by sudden, nonlinear switching at thresholds. We review the general criterion that determines whether a linear system can self-oscillate. We then describe the limiting cycles of the simplest nonlinear self-oscillators, as well as the ability of two or more coupled self-oscillators to become spontaneously synchronized (“entrained”). We characterize the operation of motors as self-oscillation and prove a theorem about their limit efficiency, of which Carnot’s theorem for heat engines appears as a special case. We briefly discuss how self-oscillation applies to servomechanisms, Cepheid variable stars, lasers, and the macroeconomic business cycle, among other applications. Our emphasis throughout is on the energetics of self-oscillation, often neglected by the literature on nonlinear dynamical systems.
Page, P R
2003-01-01
We review the status of hybrid baryons. The only known way to study hybrids rigorously is via excited adiabatic potentials. Hybrids can be modelled by both the bag and flux-tube models. The low-lying hybrid baryon is N 1/2^+ with a mass of 1.5-1.8 GeV. Hybrid baryons can be produced in the glue-rich processes of diffractive gamma N and pi N production, Psi decays and p pbar annihilation.
Hyperchaotic Oscillator with Gyrators
DEFF Research Database (Denmark)
Tamasevicius, A; Cenys, A; Mykolaitis, G.
1997-01-01
A fourth-order hyperchaotic oscillator is described. It contains a negative impedance converter, two gyratots, two capacitors and a diode. The dynamics of the oscillator is shown to be characterised by two positive Lyapunov exponents. The performance of the circuit is investigated by means...
Houdek, G
2010-01-01
In this short review on stellar convection dynamics I address the following, currently very topical, issues: (1) the surface effects of the Reynolds stresses and nonadiabaticity on solar-like pulsation frequencies, and (2) oscillation mode lifetimes of stochastically excited oscillations in red giants computed with different time-dependent convection formulations.
Dwyer, D A
2015-01-01
A concise summary of the "Oscillation at low energies" parallel session at the 2014 Neutrino Oscillation Workshop is provided. Plans to use man-made neutrinos and antineutrinos to determine the neutrino mass hierarchy, search for sterile neutrinos, and to observe coherent neutrino-nucleus scattering were discussed. Potential measurements of solar neutrinos, supernova neutrinos, and geoneutrinos are also summarized.
Hyperchaotic Oscillator with Gyrators
DEFF Research Database (Denmark)
Tamasevicius, A; Cenys, A; Mykolaitis, G.;
1997-01-01
A fourth-order hyperchaotic oscillator is described. It contains a negative impedance converter, two gyratots, two capacitors and a diode. The dynamics of the oscillator is shown to be characterised by two positive Lyapunov exponents. The performance of the circuit is investigated by means...
Energy Technology Data Exchange (ETDEWEB)
Rodrigues, R. de Lima [Universidade Federal de Campina Grande (UFCG), Cuite, PB (Brazil). Centro de Tecnologia. Unidade Academica de Educacao]. E-mail: rafael@df.ufcg.edu.br; rafaelr@cbpf.br
2007-07-01
In the present work we obtain a new representation for the Dirac oscillator based on the Clifford algebra C 7. The symmetry breaking and the energy eigenvalues for our model of the Dirac oscillator are studied in the non-relativistic limit. (author)
Disentangling neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Cohen, Andrew G. [Physics Department, Boston University, Boston, MA 02215 (United States)], E-mail: cohen@bu.edu; Glashow, Sheldon L. [Physics Department, Boston University, Boston, MA 02215 (United States)], E-mail: slg@bu.edu; Ligeti, Zoltan [Ernest Orlando Lawrence Berkeley National Laboratory, University of California, Berkeley, CA 94720 (United States)], E-mail: ligeti@lbl.gov
2009-07-13
The theory underlying neutrino oscillations has been described at length in the literature. The neutrino state produced by a weak decay is usually portrayed as a linear superposition of mass eigenstates with, variously, equal energies or equal momenta. We point out that such a description is incorrect, that in fact, the neutrino is entangled with the other particle or particles emerging from the decay. We offer an analysis of oscillation phenomena involving neutrinos (applying equally well to neutral mesons) that takes entanglement into account. Thereby we present a theoretically sound proof of the universal validity of the oscillation formulae ordinarily used. In so doing, we show that the departures from exponential decay reported by the GSI experiment cannot be attributed to neutrino mixing. Furthermore, we demonstrate that the 'Moessbauer' neutrino oscillation experiment proposed by Raghavan, while technically challenging, is correctly and unambiguously describable by means of the usual oscillation formalae.
1981-12-01
13333 ,0 .......... 10 0 .0 .781112 . . 5247 0 110.0 0 41130 0 .. 75000 . .0.0 0 0 0 10016 ...... 22246 1 0 0 1 0 .0 .59 .11 .. 30 0... 0508.0 0 0 .0 0 7...1A ...... 9933 0 1 1 0 .0 0 61 .1 65. 0 10833 0 o00 05 3ss4.850110.30 0 61 3 ... 5000 0 .0 .0 0 0 0 9614. 4 ’ . .0551 0 0 0 11 . . 0 13333 *0...9I B-6 ~~ ~~~ -------- >1 - _ _ -, - u + - I I U . .. .. -. .. . I ISO I 17 * . ........ - -... K .LI. 2.0 * • I h I +I I YGA - IMA
Boxing with neutrino oscillations
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.
Gavrilik, A M; Rebesh, A P
2010-01-01
We study the properties of sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p,q-oscillator, the 3-, 4- and 5-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consequtive energy levels satisfy the relation E_{n+1}=\\lambda E_n+\\rho E_{n-1} with real constants \\lambda, \\rho. On the other hand, for certain \\mu-oscillator known from 1993 we prove the fact of its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed among which for the \\mu$-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with non-constant, n-dependent coefficients \\lambda and \\rho. Various aspects of the QF relation are elaborated for the \\mu-oscillator and some of its extensions.
Gavrilik, A. M.; Kachurik, I. I.; Rebesh, A. P.
2010-06-01
We study the properties of the sequences of the energy eigenvalues for some generalizations of q-deformed oscillators including the p, q-oscillator, and the three-, four- and five-parameter deformed oscillators given in the literature. It is shown that most of the considered models belong to the class of so-called Fibonacci oscillators for which any three consecutive energy levels satisfy the relation En + 1 = λEn + ρEn - 1 with real constants λ, ρ. On the other hand, for a certain μ-oscillator known since 1993, we prove its non-Fibonacci nature. Possible generalizations of the three-term Fibonacci relation are discussed, among which for the μ-oscillator we choose, as the most adequate, the so-called quasi-Fibonacci (or local Fibonacci) property of the energy levels. The property is encoded in the three-term quasi-Fibonacci (QF) relation with the non-constant, n-dependent coefficients λ and ρ. Various aspects of the QF relation are elaborated for the μ-oscillator and some of its extensions.
Simulations of Sawtooth Oscillations In CTH
Roberds, Nicholas; Guazzotto, Luca; Hanson, James; Maurer, David
2015-11-01
Sawteeth are driven relaxation oscillations seen in tokamaks. Experimentally, they can be reproduced reliably. They affect the confinement of the plasma core, and in some circumstances can trigger disruptions. Sawtoothing has been observed in the Compact Toroidal Hybrid (CTH), a tokamak-stellarator hybrid having a non-axisymmetric equilibrium field. We present novel numerical simulations of sawtooth oscillations in this tokamak-stellarator hybrid. Results are contrasted and compared with simulations of a small ohmic tokamak that resembles CTH without the helical stellarator field. We have used NIMROD to conduct these extended-MHD simulations in toroidal geometry. Sawtooth simulations are obtained by starting with a stable ideal MHD equilibrium from VMEC, and driving the central safety factor below unity with an applied loop voltage. The challenges of sawtooth simulations with 3D equilibrium fields are discussed. This material is based upon work supported by Auburn University and the U.S. Department of Energy, Office of Science, Office of Fusion Energy Sciences under Award Number DE-FG02-03ER54692.
Oscillating Filaments: I - Oscillation and Geometrical Fragmentation
Gritschneder, Matthias; Burkert, Andreas
2016-01-01
We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid based AMR-code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, e.g. with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process `geometrical fragmentation'. In our realization the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristical scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. ...
Energy Technology Data Exchange (ETDEWEB)
West, J.G.W. [Electrical Machines (United Kingdom)
1997-07-01
The reasons for adopting hybrid vehicles result mainly from the lack of adequate range from electric vehicles at an acceptable cost. Hybrids can offer significant improvements in emissions and fuel economy. Series and parallel hybrids are compared. A combination of series and parallel operation would be the ideal. This can be obtained using a planetary gearbox as a power split device allowing a small generator to transfer power to the propulsion motor giving the effect of a CVT. It allows the engine to run at semi-constant speed giving better fuel economy and reduced emissions. Hybrid car developments are described that show the wide range of possible hybrid systems. (author)
Synchronization of hyperchaotic oscillators
DEFF Research Database (Denmark)
Tamasevicius, A.; Cenys, A.; Mykolaitis, G.
1997-01-01
Synchronization of chaotic oscillators is believed to have promising applications in secure communications. Hyperchaotic systems with multiple positive Lyapunov exponents (LEs) have an advantage over common chaotic systems with only one positive LE. Three different types of hyperchaotic electronic...
Neutrino anomalies without oscillations
Indian Academy of Sciences (India)
Sandip Pakvasa
2000-01-01
I review explanations for the three neutrino anomalies (solar, atmospheric and LSND) which go beyond the `conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well.
High frequency nanotube oscillator
Peng, Haibing [Houston, TX; Zettl, Alexander K [Kensington, TX
2012-02-21
A tunable nanostructure such as a nanotube is used to make an electromechanical oscillator. The mechanically oscillating nanotube can be provided with inertial clamps in the form of metal beads. The metal beads serve to clamp the nanotube so that the fundamental resonance frequency is in the microwave range, i.e., greater than at least 1 GHz, and up to 4 GHz and beyond. An electric current can be run through the nanotube to cause the metal beads to move along the nanotube and changing the length of the intervening nanotube segments. The oscillator can operate at ambient temperature and in air without significant loss of resonance quality. The nanotube is can be fabricated in a semiconductor style process and the device can be provided with source, drain, and gate electrodes, which may be connected to appropriate circuitry for driving and measuring the oscillation. Novel driving and measuring circuits are also disclosed.
Neural Oscillators Programming Simplified
Directory of Open Access Journals (Sweden)
Patrick McDowell
2012-01-01
Full Text Available The neurological mechanism used for generating rhythmic patterns for functions such as swallowing, walking, and chewing has been modeled computationally by the neural oscillator. It has been widely studied by biologists to model various aspects of organisms and by computer scientists and robotics engineers as a method for controlling and coordinating the gaits of walking robots. Although there has been significant study in this area, it is difficult to find basic guidelines for programming neural oscillators. In this paper, the authors approach neural oscillators from a programmer’s point of view, providing background and examples for developing neural oscillators to generate rhythmic patterns that can be used in biological modeling and robotics applications.
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.
Atmospheric neutrino oscillations
Giacomelli, G; Antolini, R; Baldini, A; Barbarino, G C; Barish, B C; Battistoni, G; Becherini, Y; Bellotti, R; Bemporad, C; Bernardini, P; Bilokon, H; Bloise, C; Bower, C; Brigida, M; Cafagna, F; Campana, D; Carboni, M; Cecchini, S; Cei, F; Chiarella, V; Chiarusi, T; Choudhary, B C; Coutu, S; Cozzi, M; De Cataldo, G; Dekhissi, H; De Marzo, C; De Mitri, I; Derkauoi, J; De Vincenzi, M; Di Credico, A; Esposito, L; Forti, C; Fusco, P; Giannini, G; Giglietto, N; Giorgini, M; Grassi, M; Grillo, A; Gustavino, C; Habig, A; Hanson, K; Heinz, R; Iarocci, E; Katsavounidis, E; Katsavounidis, I; Kearns, E; Kim, H; Kumar, A; Kyriazopoulou, S; Lamanna, E; Lane, C; Levin, D S; Lipari, P; Longo, M J; Loparco, F; Maaroufi, F; Mancarella, G; Mandrioli, G; Manzoor, S; Margiotta, A; Marini, A; Martello, D; Marzari-Chiesa, A; Mazziotta, M N; Mengucci, A; Michael, D G; Monacelli, P; Montaruli, T; Monteno, M; Mufson, S; Musser, J; Nicolò, D; Nolty, R; Orth, C; Osteria, G; Palamara, O; Patera, V; Patrizii, L; Pazzi, R; Peck, C W; Perrone, L; Petrera, S; Popa, V; Rainó, A; Reynoldson, J; Ronga, F; Satriano, C; Scapparone, E; Scholberg, K; Sciubba, A; Sioli, M; Sirri, G; Sitta, M; Spinelli, P; Spinetti, M; Spurio, M; Steinberg, R; Stone, J L; Sulak, L R; Surdo, A; Tarle, G; Togo, V; Vakili, M; Walter, C W; Webb, R
2005-01-01
The latest results from the Soudan 2, MACRO and SuperKamiokande experiments on atmospheric neutrino oscillations are summarised and discussed. In particular a discussion is made on the Monte Carlo simulations used for the atmospheric neutrino flux.
Oscillations in counting statistics
Wilk, Grzegorz
2016-01-01
The very large transverse momenta and large multiplicities available in present LHC experiments on pp collisions allow a much closer look at the corresponding distributions. Some time ago we discussed a possible physical meaning of apparent log-periodic oscillations showing up in p_T distributions (suggesting that the exponent of the observed power-like behavior is complex). In this talk we concentrate on another example of oscillations, this time connected with multiplicity distributions P(N). We argue that some combinations of the experimentally measured values of P(N) (satisfying the recurrence relations used in the description of cascade-stochastic processes in quantum optics) exhibit distinct oscillatory behavior, not observed in the usual Negative Binomial Distributions used to fit data. These oscillations provide yet another example of oscillations seen in counting statistics in many different, apparently very disparate branches of physics further demonstrating the universality of this phenomenon.
Oscillating Filaments. I. Oscillation and Geometrical Fragmentation
Gritschneder, Matthias; Heigl, Stefan; Burkert, Andreas
2017-01-01
We study the stability of filaments in equilibrium between gravity and internal as well as external pressure using the grid-based AMR code RAMSES. A homogeneous, straight cylinder below a critical line mass is marginally stable. However, if the cylinder is bent, such as with a slight sinusoidal perturbation, an otherwise stable configuration starts to oscillate, is triggered into fragmentation, and collapses. This previously unstudied behavior allows a filament to fragment at any given scale, as long as it has slight bends. We call this process “geometrical fragmentation.” In our realization, the spacing between the cores matches the wavelength of the sinusoidal perturbation, whereas up to now, filaments were thought to be only fragmenting on the characteristic scale set by the mass-to-line ratio. Using first principles, we derive the oscillation period as well as the collapse timescale analytically. To enable a direct comparison with observations, we study the line-of-sight velocity for different inclinations. We show that the overall oscillation pattern can hide the infall signature of cores.
Power Oscillations Damping in DC Microgrids
DEFF Research Database (Denmark)
Hamzeh, Mohsen; Ghafouri, Mohsen; Karimi, Houshang
2016-01-01
This paper proposes a new control strategy for damping of power oscillations in a multi-source dc microgrid. A parallel combination of a fuel cell (FC), a photovoltaic (PV) system and a supercapacitor (SC) are used as a hybrid power conversion system (HPCS). The SC compensates for the slow...... transient response of the FC stack. The HPCS controller comprises a multi-loop voltage controller and a virtual impedance loop for power management. The virtual impedance loop uses a dynamic droop gain to actively damp the low-frequency oscillations of the power sharing control unit. The gain of virtual...... impedance loop is determined using small signal analysis and pole placement method. The Mesh analysis is employed to further study the stability of low-frequency modes of the overall dc microgrid. Moreover, based on the guardian map theorem, a robust stability analysis is carried out to determine...
Indirect neutrino oscillations
Babu, K S; Wilczek, Frank; Pati, Jogesh C; Wilczek, Frank
1995-01-01
We show how two different scales for oscillations between e and \\mu neutrinos, characterized by different mixing angles and effective mass scales, can arise in a simple and theoretically attractive framework. One scale characterizes direct oscillations, which can accommodate the MSW approach to the solar neutrino problem, whereas the other can be considered as arising indirectly, through virtual transitions involving the \\tau neutrino with a mass \\sim 1 eV. This indirect transition allows the possibility of observable \\bar \
Kayser, Boris
2012-01-01
To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also prov...
Ultrastable Multigigahertz Photonic Oscillator
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.
Scuflaire, R; Théado, S; Bourge, P -O; Miglio, A; Godart, M; Thoul, A; Noels, A
2007-01-01
The Liege Oscillation code can be used as a stand-alone program or as a library of subroutines that the user calls from a Fortran main program of his own to compute radial and non-radial adiabatic oscillations of stellar models. We describe the variables and the equations used by the program and the methods used to solve them. A brief account is given of the use and the output of the program.
Jenkins, Alejandro
2011-01-01
Physicists are very familiar with forced and parametric resonance, but usually not with self-oscillation, a property of certain linear systems that gives rise to a great variety of vibrations, both useful and destructive. In a self-oscillator, the driving force is controlled by the oscillation itself so that it acts in phase with the velocity, causing a negative damping that feeds energy from the environment into the vibration: no external rate needs to be tuned to the resonant frequency. A paper from 1830 by G. B. Airy gives us the opening to introduce self-oscillation as a sort of "perpetual motion" responsible for the human voice. The famous collapse of the Tacoma Narrows bridge in 1940, often attributed by introductory physics texts to forced resonance, was actually a self-oscillation, as was the more recent swaying of the London Millenium Footbridge. Clocks are self-oscillators, as are bowed and wind musical instruments, and the heartbeat. We review the criterion that determines whether an arbitrary line...
Frequency of self-oscillations
Groszkowski, Janusz
2013-01-01
Frequency of Self-Oscillations covers the realm of electric oscillations that plays an important role both in the scientific and technical aspects. This book is composed of nine chapters, and begins with the introduction to the alternating currents and oscillation. The succeeding chapters deal with the free oscillations in linear isolated systems. These topics are followed by discussions on self-oscillations in linear systems. Other chapters describe the self-oscillations in non-linear systems, the influence of linear elements on frequency of oscillations, and the electro mechanical oscillato
Energy Technology Data Exchange (ETDEWEB)
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.
Coalescence in coupled Duffing oscillators
Institute of Scientific and Technical Information of China (English)
YANG Jun-Zhong
2009-01-01
The forced Duffing oscillator has a pair of symmetrical attractors in a proper parameter regime. When a lot of Duffing oscillators are coupled linearly, the system tends to form clusters in which the neighboring oscillators fall onto the same attractor. When the coupling strength is strong, all of the oscillators fall onto one attractor. In this work, we investigate coalescence in the coupled forced Duffing oscillators. Some phenomena are found and explanations are presented.
Energy Technology Data Exchange (ETDEWEB)
Atakishiyev, Natig M [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Klimyk, Anatoliy U [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico); Wolf, Kurt Bernardo [Centro de Ciencias FIsicas, UNAM, Apartado Postal 48-3, 62251 Cuernavaca, Morelos (Mexico)
2004-05-28
The finite q-oscillator is a model that obeys the dynamics of the harmonic oscillator, with the operators of position, momentum and Hamiltonian being functions of elements of the q-algebra su{sub q}(2). The spectrum of position in this discrete system, in a fixed representation j, consists of 2j + 1 'sensor'-points x{sub s} = 1/2 [2s]{sub q}, s element of {l_brace}-j, -j+1, ..., j{r_brace}, and similarly for the momentum observable. The spectrum of energies is finite and equally spaced, so the system supports coherent states. The wavefunctions involve dual q-Kravchuk polynomials, which are solutions to a finite-difference Schroedinger equation. Time evolution (times a phase) defines the fractional Fourier-q-Kravchuk transform. In the classical limit as q {yields} 1 we recover the finite oscillator Lie algebra, the N = 2j {yields} {infinity} limit returns the Macfarlane-Biedenharn q-oscillator and both limits contract the generators to the standard quantum-mechanical harmonic oscillator.
Atakishiyev, Natig M.; Klimyk, Anatoliy U.; Wolf, Kurt Bernardo
2004-05-01
The finite q-oscillator is a model that obeys the dynamics of the harmonic oscillator, with the operators of position, momentum and Hamiltonian being functions of elements of the q-algebra suq(2). The spectrum of position in this discrete system, in a fixed representation j, consists of 2j + 1 'sensor'-points x_s={\\case12}[2s]_q, s\\in\\{-j,-j+1,\\ldots,j\\} , and similarly for the momentum observable. The spectrum of energies is finite and equally spaced, so the system supports coherent states. The wavefunctions involve dual q-Kravchuk polynomials, which are solutions to a finite-difference Schrödinger equation. Time evolution (times a phase) defines the fractional Fourier-q-Kravchuk transform. In the classical limit as q rarr 1 we recover the finite oscillator Lie algebra, the N = 2j rarr infin limit returns the Macfarlane-Biedenharn q-oscillator and both limits contract the generators to the standard quantum-mechanical harmonic oscillator.
Oscillate boiling from microheaters
Li, Fenfang; Gonzalez-Avila, S. Roberto; Nguyen, Dang Minh; Ohl, Claus-Dieter
2017-01-01
We report about an intriguing boiling regime occurring for small heaters embedded on the boundary in subcooled water. The microheater is realized by focusing a continuous wave laser beam to about 10 μ m in diameter onto a 165-nm-thick layer of gold, which is submerged in water. After an initial vaporous explosion a single bubble oscillates continuously and repeatedly at several 100 kHz albeit with constant laser power input. The microbubble's oscillations are accompanied with bubble pinch-off, leading to a stream of gaseous bubbles in the subcooled water. The self-driven bubble oscillation is explained with a thermally kicked oscillator caused by surface attachment and by the nonspherical collapses. Additionally, Marangoni stresses induce a recirculating streaming flow which transports cold liquid towards the microheater, reducing diffusion of heat along the substrate and therefore stabilizing the phenomenon to many million cycles. We speculate that this oscillate boiling regime may overcome the heat transfer thresholds observed during the nucleate boiling crisis and offers a new pathway for heat transfer under microgravity conditions.
Oscillations following periodic reinforcement.
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.
Oscillations in stellar superflares
Balona, L A; Kosovichev, A; Nakariakov, V M; Pugh, C E; Van Doorsselaere, T
2015-01-01
Two different mechanisms may act to induce quasi-periodic pulsations (QPP) in whole-disk observations of stellar flares. One mechanism may be magneto-hydromagnetic (MHD) forces and other processes acting on flare loops as seen in the Sun. The other mechanism may be forced local acoustic oscillations due to the high-energy particle impulse generated by the flare (known as `sunquakes' in the Sun). We analyze short-cadence Kepler data of 257 flares in 75 stars to search for QPP in the flare decay branch or post-flare oscillations which may be attributed to either of these two mechanisms. About 18 percent of stellar flares show a distinct bump in the flare decay branch of unknown origin. The bump does not seem to be a highly-damped global oscillation because the periods of the bumps derived from wavelet analysis do not correlate with any stellar parameter. We detected damped oscillations covering several cycles (QPP), in seven flares on five stars. The periods of these oscillations also do not correlate with any ...
Environmentally compatible solder materials for thick film hybrid assemblies
Energy Technology Data Exchange (ETDEWEB)
Hosking, F.M.; Vianco, P.T.; Rejent, J.A.; Hernandez, C.L. [Sandia National Labs., Albuquerque, NM (United States). Materials and Process Sciences Center
1997-02-01
New soldering materials and processes have been developed over the last several years to address a variety of environmental issues. One of the primary efforts by the electronics industry has involved the development of alternative solders to replace the traditional lead-containing alloys. Sandia National Laboratories is developing such alternative solder materials for printed circuit board and hybrid microcircuit (HMC) applications. This paper describes the work associated with low residue, lead-free soldering of thick film HMC`s. The response of the different materials to wetting, aging, and mechanical test conditions was investigated. Hybrid test vehicles were designed and fabricated with a variety of chip capacitors and leadless ceramic chip carriers to conduct thermal, electrical continuity, and mechanical evaluations of prototype joints. Microstructural development along the solder and thick film interface, after isothermal solid state aging over a range of elevated temperatures and times, was quantified using microanalytical techniques. Flux residues on soldered samples were stressed (temperature-humidity aged) to identify potential corrosion problems. Mechanical tests also supported the development of a solder joint lifetime prediction model. Progress of this effort is summarized.
Arbitrary Spin Galilean Oscillator
Hagen, C R
2014-01-01
The so-called Dirac oscillator was proposed as a modification of the free Dirac equation which reproduces many of the properties of the simple harmonic oscillator but accompanied by a strong spin-orbit coupling term. It has yet to be extended successfully to the arbitrary spin S case primarily because of the unwieldiness of general spin Lorentz invariant wave equations. It is shown here using the formalism of totally symmetric multispinors that the Dirac oscillator can, however, be made to accommodate spin by incorporating it into the framework of Galilean relativity. This is done explicitly for spin zero and spin one as special cases of the arbitrary spin result. For the general case it is shown that the coefficient of the spin-orbit term has a 1/S behavior by techniques which are virtually identical to those employed in the derivation of the g-factor carried out over four decades ago.
Energy Technology Data Exchange (ETDEWEB)
Hoeye, Gudrun Kristine
1999-07-01
We have studied radial and nonradial oscillations in neutron stars, both in a general relativistic and non-relativistic frame, for several different equilibrium models. Different equations of state were combined, and our results show that it is possible to distinguish between the models based on their oscillation periods. We have particularly focused on the p-, f-, and g-modes. We find oscillation periods of II approx. 0.1 ms for the p-modes, II approx. 0.1 - 0.8 ms for the f-modes and II approx. 10 - 400 ms for the g-modes. For high-order (l (>{sub )} 4) f-modes we were also able to derive a formula that determines II{sub l+1} from II{sub l} and II{sub l-1} to an accuracy of 0.1%. Further, for the radial f-mode we find that the oscillation period goes to infinity as the maximum mass of the star is approached. Both p-, f-, and g-modes are sensitive to changes in the central baryon number density n{sub c}, while the g-modes are also sensitive to variations in the surface temperature. The g-modes are concentrated in the surface layer, while p- and f-modes can be found in all parts of the star. The effects of general relativity were studied, and we find that these are important at high central baryon number densities, especially for the p- and f-modes. General relativistic effects can therefore not be neglected when studying oscillations in neutron stars. We have further developed an improved Cowling approximation in the non-relativistic frame, which eliminates about half of the gap in the oscillation periods that results from use of the ordinary Cowling approximation. We suggest to develop an improved Cowling approximation also in the general relativistic frame. (Author)
Nonlinear harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Calogero, F [Dipartimento di Fisica, Universita di Roma ' La Sapienza' (Italy); Inozemtsev, V I [Joint Institute for Nuclear Research, Dubna (Russian Federation)
2002-12-06
The existence is noted of assemblies of an arbitrary number of complex oscillators, or equivalently, of an arbitrary even number of real oscillators, characterized by Newtonian equations of motion ('acceleration equal force') with one-body velocity-dependent linear forces and many-body velocity-independent cubic forces, all the nonsingular solutions of which are isochronous (completely periodic with the same period). As for the singular solutions, as usual they emerge, in the context of the initial-value problem, from a closed domain in phase space having lower dimensionality.
Prediction of resonant oscillation
DEFF Research Database (Denmark)
2010-01-01
The invention relates to methods for prediction of parametric rolling of vessels. The methods are based on frequency domain and time domain information in order do set up a detector able to trigger an alarm when parametric roll is likely to occur. The methods use measurements of e.g. pitch and roll...... oscillations and compare the measured oscillations using FFT analysis of signal correlations, variance analysis of signals and other comparisons. As an example, the presence of a growing peak around a frequency that doubles the roll natural frequency indicates the possibility that parametric roll is going...
Friedel oscillations in graphene
DEFF Research Database (Denmark)
Lawlor, J. A.; Power, S. R.; Ferreira, M.S.
2013-01-01
Symmetry breaking perturbations in an electronically conducting medium are known to produce Friedel oscillations in various physical quantities of an otherwise pristine material. Here we show in a mathematically transparent fashion that Friedel oscillations in graphene have a strong sublattice...... asymmetry. As a result, the presence of impurities and/or defects may impact the distinct graphene sublattices very differently. Furthermore, such an asymmetry can be used to explain the recent observations that nitrogen atoms and dimers are not randomly distributed in graphene but prefer to occupy one...
Krauss, L.; Wilczek, F.
1985-01-01
The theory of oscillations of solar neutrinos is developed as it applies to the electron-recoil spectrum in neutrino-electron scattering. The spectral information obtained by such measurements (as opposed to counting total event rates) is crucial for allowing observation of neutrino oscillations for masses down to 500 neV. In this regard, the effects of different masses and mixing angles, as well as such subtleties as thermal and pressure broadening, finite solar-core size, and variable indices of refraction are investigated.
Oscillation Baselining and Analysis Tool
Energy Technology Data Exchange (ETDEWEB)
2017-03-27
PNNL developed a new tool for oscillation analysis and baselining. This tool has been developed under a new DOE Grid Modernization Laboratory Consortium (GMLC) Project (GM0072 - “Suite of open-source applications and models for advanced synchrophasor analysis”) and it is based on the open platform for PMU analysis. The Oscillation Baselining and Analysis Tool (OBAT) performs the oscillation analysis and identifies modes of oscillations (frequency, damping, energy, and shape). The tool also does oscillation event baselining (fining correlation between oscillations characteristics and system operating conditions).
Popov, V. D.; Khamidullina, N. M.
2006-10-01
In developing radio-electronic devices (RED) of spacecraft operating in the fields of ionizing radiation in space, one of the most important problems is the correct estimation of their radiation tolerance. The “weakest link” in the element base of onboard microelectronic devices under radiation effect is the integrated microcircuits (IMC), especially of large scale (LSI) and very large scale (VLSI) degree of integration. The main characteristic of IMC, which is taken into account when making decisions on using some particular type of IMC in the onboard RED, is the probability of non-failure operation (NFO) at the end of the spacecraft’s lifetime. It should be noted that, until now, the NFO has been calculated only from the reliability characteristics, disregarding the radiation effect. This paper presents the so-called “reliability” approach to determination of radiation tolerance of IMC, which allows one to estimate the probability of non-failure operation of various types of IMC with due account of radiation-stimulated dose failures. The described technique is applied to RED onboard the Spektr-R spacecraft to be launched in 2007.
Single-atom quantum control of macroscopic mechanical oscillators
Bariani, F.; Otterbach, J.; Tan, Huatang; Meystre, P.
2014-01-01
We investigate a hybrid electromechanical system consisting of a pair of charged macroscopic mechanical oscillators coupled to a small ensemble of Rydberg atoms. The resonant dipole-dipole coupling between an internal atomic Rydberg transition and the mechanics allows cooling to its motional ground state with a single atom despite the considerable mass imbalance between the two subsystems. We show that the rich electronic spectrum of Rydberg atoms, combined with their high degree of optical control, paves the way towards implementing various quantum-control protocols for the mechanical oscillators.
Oscillators and operational amplifiers
DEFF Research Database (Denmark)
Lindberg, Erik
2005-01-01
A generalized approach to the design of oscillators using operational amplifiers as active elements is presented. A piecewise-linear model of the amplifier is used so that it make sense to investigate the eigenvalues of the Jacobian of the differential equations. The characteristic equation...
[Oscillating physiotherapy for secretolysis].
Brückner, U
2008-03-01
Assisted coughing and mechanical cough aids compensate for the weak cough flow in patients with neuromuscular diseases (NMD). In cases with preserved respiratory muscles also breathing techniques and special devices, e. g., flutter or acapella can be used for secretion mobilisation during infections of the airways. These means are summarised as oscillating physiotherapy. Their mechanisms are believed to depend on separation of the mucus from the bronchial wall by vibration, thus facilitating mucus transport from the peripheral to the central airways. In mucoviscidosis and chronic obstructive pulmonary disease their application is established, but there is a paucity of data regarding the commitment in patients with neuromuscular diseases. The effective adoption of simple oscillation physiotherapeutic interventions demands usually a sufficient force of the respiratory muscles--exceptions are the application of the percussionaire (intrapulmonary percussive ventilator, IPV) or high frequency chest wall oscillation (HFCWO). In daily practice there is evidence that patients with weak respiratory muscles are overstrained with the use of these physiotherapeutic means, or get exhausted. A general recommendation for the adoption of simple oscillating physiotherapeutic interventions cannot be made in patients with NMDs. Perhaps in the future devices such as IPV or HFCWO will prove to be more effective in NMD patients.
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.
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef;
2007-01-01
A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...
Neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Camilleri, L. [European Organization for Nuclear Research, Geneva (Switzerland)
1996-11-01
Neutrino oscillation experiments ({nu}{sub {mu}}{yields}{nu}{sub e} and {nu}{sub {mu}}{yields}{nu}{sub {tau}}) currently being performed at accelerators are reviewed. Future plans for short and long base-line experiments are summarized. (author) 10 figs., 2 tabs., 29 refs.
Multiphoton coherent population oscillation
Sharypov, A V
2014-01-01
We study the bichromatic driving of a two-level system which displays long-lived coherent population oscillations (CPO). We show that under certain conditions, multiphoton parametric interaction leads to the appearance of CPO resonances at the subharmonic frequencies. In addition, in the region of the CPO resonances, there is strong parametric interaction between the weak sideband components of the electromagnetic field.
From excitability to oscillations
DEFF Research Database (Denmark)
Postnov, D. E.; Neganova, A. Y.; Jacobsen, J. C. B.;
2013-01-01
One consequence of cell-to-cell communication is the appearance of synchronized behavior, where many cells cooperate to generate new dynamical patterns. We present a simple functional model of vasomotion based on the concept of a two-mode oscillator with dual interactions: via relatively slow...
Proprioceptive evoked gamma oscillations
DEFF Research Database (Denmark)
Arnfred, S.M.; Hansen, Lars Kai; Parnas, J.;
2007-01-01
to evoke gamma oscillations. EEG was recorded using 64 channels in 14 healthy subjects. In each of three runs a stimulus of 100 g load increment in each hand was presented in 120 trials. Data were wavelet transformed and runs collapsed. Inter-trial phase coherence (ITPC) was computed as the best measure...
Neutrino Velocity and Neutrino Oscillations
Minakata, H
2012-01-01
We study distances of propagation and the group velocities of the muon neutrinos in the presence of mixing and oscillations assuming that Lorentz invariance holds. Oscillations lead to distortion of the $\
Microwave transistor oscillator frequency tripling
B. A. Kotserzhynskyi
2010-01-01
The frequency tripler state of the art is consided. The oscillator-frequency tripler design is now at the state of scientific research. Microwave companies release the devices of the such structure: oscillator, buffer, amplifier-tripler.
Microwave transistor oscillator frequency tripling
Directory of Open Access Journals (Sweden)
B. A. Kotserzhynskyi
2010-01-01
Full Text Available The frequency tripler state of the art is consided. The oscillator-frequency tripler design is now at the state of scientific research. Microwave companies release the devices of the such structure: oscillator, buffer, amplifier-tripler.
Neutrino Oscillations with Nil Mass
Floyd, Edward R.
2016-09-01
An alternative neutrino oscillation process is presented as a counterexample for which the neutrino may have nil mass consistent with the standard model. The process is developed in a quantum trajectories representation of quantum mechanics, which has a Hamilton-Jacobi foundation. This process has no need for mass differences between mass eigenstates. Flavor oscillations and ν ,bar{ν } oscillations are examined.
2013-01-01
The main goal of this book is to provide a state of the art of hybrid metaheuristics. The book provides a complete background that enables readers to design and implement hybrid metaheuristics to solve complex optimization problems (continuous/discrete, mono-objective/multi-objective, optimization under uncertainty) in a diverse range of application domains. Readers learn to solve large scale problems quickly and efficiently combining metaheuristics with complementary metaheuristics, mathematical programming, constraint programming and machine learning. Numerous real-world examples of problems and solutions demonstrate how hybrid metaheuristics are applied in such fields as networks, logistics and transportation, bio-medical, engineering design, scheduling.
Resurgence of oscillation in coupled oscillators under delayed cyclic interaction
Bera, Bidesh K.; Majhi, Soumen; Ghosh, Dibakar
2017-07-01
This paper investigates the emergence of amplitude death and revival of oscillations from the suppression states in a system of coupled dynamical units interacting through delayed cyclic mode. In order to resurrect the oscillation from amplitude death state, we introduce asymmetry and feedback parameter in the cyclic coupling forms as a result of which the death region shrinks due to higher asymmetry and lower feedback parameter values for coupled oscillatory systems. Some analytical conditions are derived for amplitude death and revival of oscillations in two coupled limit cycle oscillators and corresponding numerical simulations confirm the obtained theoretical results. We also report that the death state and revival of oscillations from quenched state are possible in the network of identical coupled oscillators. The proposed mechanism has also been examined using chaotic Lorenz oscillator.
Voltage-controlled photonic oscillator.
Savchenkov, A A; Ilchenko, V S; Liang, W; Eliyahu, D; Matsko, A B; Seidel, D; Maleki, L
2010-05-15
We report the development and demonstration of an X-band voltage-controlled photonic oscillator based on a whispering gallery mode resonator made of an electro-optic crystalline material. The oscillator has good spectral purity and wide, agile, linear tunability. We have modified the existing theoretical model of the opto-electronic oscillator to describe the performance of our tunable oscillator and have found a good agreement between the theoretical predictions and the measurement results. We show that the device is promising for higher-frequency applications where high-performance tunable oscillators with wide tunability do not exist.
Entanglement in neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Blasone, M.; Dell' Anno, F.; De Siena, S.; Illuminati, F. [Universita degli Studi di Salerno Via Ponte don Melillon, Dipt. di Matematica e Informatica, Fisciano SA (Italy); INFN Sezione di Napoli, Gruppo collegato di Salerno - Baronissi SA (Italy); Dell' Anno, F.; De Siena, S.; Illuminati, F. [CNR-INFM Coherentia - Napoli (Italy); Blasone, M. [ISI Foundation for Scientific Interchange, Torino (Italy)
2009-03-15
Flavor oscillations in elementary particle physics are related to multimode entanglement of single-particle states. We show that mode entanglement can be expressed in terms of flavor transition probabilities, and therefore that single-particle entangled states acquire a precise operational characterization in the context of particle mixing. We treat in detail the physically relevant cases of two- and three-flavor neutrino oscillations, including the effective measure of CP violation. We discuss experimental schemes for the transfer of the quantum information encoded in single-neutrino states to spatially delocalized two-flavor charged-lepton states, thus showing, at least in principle, that single-particle entangled states of neutrino mixing are legitimate physical resources for quantum information tasks. (authors)
Acoustics waves and oscillations
Sen, S.N.
2013-01-01
Parameters of acoustics presented in a logical and lucid style Physical principles discussed with mathematical formulations Importance of ultrasonic waves highlighted Dispersion of ultrasonic waves in viscous liquids explained This book presents the theory of waves and oscillations and various applications of acoustics in a logical and simple form. The physical principles have been explained with necessary mathematical formulation and supported by experimental layout wherever possible. Incorporating the classical view point all aspects of acoustic waves and oscillations have been discussed together with detailed elaboration of modern technological applications of sound. A separate chapter on ultrasonics emphasizes the importance of this branch of science in fundamental and applied research. In this edition a new chapter ''Hypersonic Velocity in Viscous Liquids as revealed from Brillouin Spectra'' has been added. The book is expected to present to its readers a comprehensive presentation of the subject matter...
Physics of Neutrino Oscillation
Mondal, Spandan
2015-01-01
The Standard Model of particle physics describes neutrinos as massless, chargeless elementary particles that come in three different flavours. However, recent experiments indicate that neutrinos not only have mass, but also have multiple mass eigenstates that are not identical to the flavour states, thereby indicating mixing. As an evidence of mixing, neutrinos have been observed to change from one flavour to another during their propagation, a phenomenon called neutrino oscillation. We have studied the reasons and derived the probabilities of neutrino flavour change, both in vacuum and in matter. We have also studied the parameters affecting this probability. We have discussed the special case of two-neutrino oscillations. Lastly, we have discussed some basic properties of neutrinos that are reflected in the previous derivations and highlighted a few relevant open problems. To begin with, we have also studied the relevant topics in introductory High Energy Physics and Quantum Mechanics to familiarize with th...
Cetorelli, Nicola
2014-01-01
I introduce the concept of hybrid intermediaries: financial conglomerates that control a multiplicity of entity types active in the "assembly line" process of modern financial intermediation, a system that has become known as shadow banking. The complex bank holding companies of today are the best example of hybrid intermediaries, but I argue that financial firms from the "nonbank" space can just as easily evolve into conglomerates with similar organizational structure, thus acquiring the cap...
CSIR Research Space (South Africa)
Jacob John, Maya
2009-04-01
Full Text Available effect was observed for the elongation at break of the hybrid composites. The impact strength of the hybrid composites increased with the addition of glass fibres. The tensile and impact properties of thermoplastic natural rubber reinforced short... panels made from conventional structural materials. Figure 3 illustrates the performance of cellular biocomposite panels against conventional systems used for building and residential construction, namely a pre- cast pre-stressed hollow core concrete...
Neutrino Masses and Oscillations
CERN. Geneva. Audiovisual Unit; Treille, Daniel
2002-01-01
This course will not cover its subject in the customary way. The emphasis will be on the simple theoretical concepts (helicity, handedness, chirality, Majorana masses) which are obscure in most of the literature, and on the quantum mechanics of oscillations, that ALL books get wrong. Which, hopefully, will not deter me from discussing some of the most interesting results from the labs and from the cosmos.
Oscillations in the bispectrum
Meerburg, P Daniel
2010-01-01
There exist several models of inflation that produce primordial bispectra that contain a large number of oscillations. In this paper we discuss these models, and aim at finding a method of detecting such bispectra in the data. We explain how the recently proposed method of mode expansion of bispectra might be able to reconstruct these spectra from separable basis functions. Extracting these basis functions from the data might then lead to observational constraints on these models.
Polychromatic optical Bloch oscillations.
Longhi, Stefano
2009-07-15
Bloch oscillations (BOs) of polychromatic beams in circularly curved optical waveguide arrays are smeared out owing to the dependence of the BO spatial period on the wavelength. Here it is shown that restoring of the self-imaging property of the array and approximate BOs over relatively broad spectral ranges can be achieved by the insertion of suitable lumped phase slips uniformly applied across the array.
Nonlinear Oscillators in Space Physics
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.
Temperature sensitive oscillator
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.
Quantum Oscillation in Narrow-Gap Topological Insulators.
Zhang, Long; Song, Xue-Yang; Wang, Fa
2016-01-29
The canonical understanding of quantum oscillation in metals is challenged by the observation of the de Haas-van Alphen effect in an insulator, SmB_{6} [Tan et al, Science 349, 287 (2015)]. Based on a two-band model with inverted band structure, we show that the periodically narrowing hybridization gap in magnetic fields can induce the oscillation of low-energy density of states in the bulk, which is observable provided that the activation energy is small and comparable to the Landau level spacing. Its temperature dependence strongly deviates from the Lifshitz-Kosevich theory. The nontrivial band topology manifests itself as a nonzero Berry phase in the oscillation pattern, which crosses over to a trivial Berry phase by increasing the temperature or the magnetic field. Further predictions to experiments are also proposed.
1997-09-30
SEP 1997 2. REPORT TYPE 3. DATES COVERED 00-00-1997 to 00-00-1997 4. TITLE AND SUBTITLE Acquisition of a Nd-Yag Pumped MOPO (Master Oscillator...unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 ACQUISITION OF A ND-YAG PUMPED MOPO (MASTER OSCILLATOR / POWER OSCILLATOR) OPTICAL...instrument is configured in a master oscillator/power oscillator configuration, hence the designation MOPO . The MOPO will be used in conjunction
Atakishiyeva, Mesuma K.; Atakishiyev, Natig M.; Wolf, Kurt Bernardo
2014-05-01
The study of irreducible representations of Lie algebras and groups has traditionally considered their action on functions of a continuous manifold (e.g. the 'rotation' Lie algebra so(3) on functions on the sphere). Here we argue that functions of a discrete variable -Kravchuk functions- are on equal footing for that study in the case of so(3). They lead to a discrete quantum model of the harmonic oscillator, and offer a corresponding set of special function relations. The technique is applicable to other special function families of a discrete variable, which stem from low-dimensional Lie algebras and are stationary solutions for the corresponding discrete quantum models.
Modeling microtubule oscillations
DEFF Research Database (Denmark)
Jobs, E.; Wolf, D.E.; Flyvbjerg, H.
1997-01-01
Synchronization of molecular reactions in a macroscopic volume may cause the volume's physical properties to change dynamically and thus reveal much about the reactions. As an example, experimental time series for so-called microtubule oscillations are analyzed in terms of a minimal model...... for this complex polymerization-depolymerization cycle. The model reproduces well the qualitatively different time series that result from different experimental conditions, and illuminates the role and importance of individual processes in the cycle. Simple experiments are suggested that can further test...... and define the model and the polymer's reaction cycle....
Linder, E V
2006-01-01
Distance-redshift data can impose strong constraints on dark energy models even when the equation of state is oscillatory. Despite the double integral dependence of the distance on the equation of state, precision measurement of the distance-redshift relation for z=0-2 is more incisive than the linear growth factor, CMB last scattering surface distance, and the age of the universe in distinguishing oscillatory behavior from an average behavior. While oscillating models might help solve the coincidence problem (since acceleration occurs periodically), next generation observations will strongly constrain such possibilities.
Góźdź, Marek
2013-01-01
It has been firmly established, that neutrinos change their flavour during propagation. This feature is attributed to the fact, that each flavour eigenstate is a superposition of three mass eigenstates, which propagate with different frequencies. This picture, although widely accepted, is wrong in the simplest approach and requires quite sophisticated treatment based on the wave-packet description within quantum field theory. In this communication we present a novel, much simpler explanation and show, that oscillations among massive particles can be obtained in a natural way. We use the framework of quantum mechanics with time being a physical observable, not just a parameter.
Brain Oscillations, Hypnosis, and Hypnotizability.
Jensen, Mark P; Adachi, Tomonori; Hakimian, Shahin
2015-01-01
This article summarizes the state-of-science knowledge regarding the associations between hypnosis and brain oscillations. Brain oscillations represent the combined electrical activity of neuronal assemblies, usually measured as specific frequencies representing slower (delta, theta, alpha) and faster (beta, gamma) oscillations. Hypnosis has been most closely linked to power in the theta band and changes in gamma activity. These oscillations are thought to play a critical role in both the recording and recall of declarative memory and emotional limbic circuits. The authors propose that this role may be the mechanistic link between theta (and perhaps gamma) oscillations and hypnosis, specifically, that the increases in theta oscillations and changes in gamma activity observed with hypnosis may underlie some hypnotic responses. If these hypotheses are supported, they have important implications for both understanding the effects of hypnosis and for enhancing response to hypnotic treatments.
Olfactory system oscillations across phyla.
Kay, Leslie M
2015-04-01
Neural oscillations are ubiquitous in olfactory systems of mammals, insects and molluscs. Neurophysiological and computational investigations point to common mechanisms for gamma or odor associated oscillations across phyla (40-100Hz in mammals, 20-30Hz in insects, 0.5-1.5Hz in molluscs), engaging the reciprocal dendrodendritic synapse between excitatory principle neurons and inhibitory interneurons in the olfactory bulb (OB), antennal lobe (AL), or procerebrum (PrC). Recent studies suggest important mechanisms that may modulate gamma oscillations, including neuromodulators and centrifugal input to the OB and AL. Beta (20Hz) and theta (2-12Hz) oscillations coordinate activity within and across brain regions. Olfactory beta oscillations are associated with odor learning and depend on centrifugal OB input, while theta oscillations are strongly associated with respiration.
Single ICCII Sinusoidal Oscillators Employing Grounded Capacitors
Directory of Open Access Journals (Sweden)
J. W. Horng
2011-09-01
Full Text Available Two inverting second-generation current conveyors (ICCII based sinusoidal oscillators are presented. The first sinusoidal oscillator is composed of one ICCII, two grounded capacitors and two resistors. The oscillation condition and oscillation frequency can be orthogonally controllable. The second sinusoidal oscillator is composed of one ICCII, two grounded capacitors and three resistors. The oscillation condition and oscillation frequency can be independently controllable through different resistors.
C P -violating baryon oscillations
McKeen, David; Nelson, Ann E.
2016-10-01
We enumerate the conditions necessary for C P violation to be manifest in n -n ¯ oscillations and build a simple model that can give rise to such effects. We discuss a possible connection between neutron oscillations and dark matter, provided the mass of the latter lies between mp-me and mp+me. We apply our results to a possible baryogenesis scenario involving C P violation in the oscillations of the Ξ0.
How pervasive are circadian oscillations?
2014-01-01
Circadian oscillations play a critical role in coordinating the physiology, homeostasis, and behavior of biological systems. Once thought to only be controlled by a master clock, recent high-throughput experiments suggest many genes and metabolites in a cell are potentially capable of circadian oscillations. Each cell can reprogram itself and select a relatively small fraction of this broad repertoire for circadian oscillations, as a result of genetic, environmental, and even diet changes.
Linearization of conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Belendez, A; Alvarez, M L [Departamento de Fisica, IngenierIa de Sistemas y TeorIa de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, E; Pascual, I [Departamento de Optica, FarmacologIa y AnatomIa, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2009-03-11
A linearization method of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force which allows us to obtain a frequency-amplitude relation which is valid not only for small but also for large amplitudes and, sometimes, for the complete range of oscillation amplitudes. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of the technique.
Nurmikko, Arto V; Donoghue, John P; Hochberg, Leigh R; Patterson, William R; Song, Yoon-Kyu; Bull, Christopher W; Borton, David A; Laiwalla, Farah; Park, Sunmee; Ming, Yin; Aceros, Juan
2010-01-01
Acquiring neural signals at high spatial and temporal resolution directly from brain microcircuits and decoding their activity to interpret commands and/or prior planning activity, such as motion of an arm or a leg, is a prime goal of modern neurotechnology. Its practical aims include assistive devices for subjects whose normal neural information pathways are not functioning due to physical damage or disease. On the fundamental side, researchers are striving to decipher the code of multiple neural microcircuits which collectively make up nature's amazing computing machine, the brain. By implanting biocompatible neural sensor probes directly into the brain, in the form of microelectrode arrays, it is now possible to extract information from interacting populations of neural cells with spatial and temporal resolution at the single cell level. With parallel advances in application of statistical and mathematical techniques tools for deciphering the neural code, extracted populations or correlated neurons, significant understanding has been achieved of those brain commands that control, e.g., the motion of an arm in a primate (monkey or a human subject). These developments are accelerating the work on neural prosthetics where brain derived signals may be employed to bypass, e.g., an injured spinal cord. One key element in achieving the goals for practical and versatile neural prostheses is the development of fully implantable wireless microelectronic "brain-interfaces" within the body, a point of special emphasis of this paper.
The Duffing oscillator with damping
DEFF Research Database (Denmark)
Johannessen, Kim
2015-01-01
An analytical solution to the differential equation describing the Duffing oscillator with damping is presented. The damping term of the differential equation and the initial conditions satisfy an algebraic equation, and thus the solution is specific for this type of damping. The nonlinear term....... It is established that the period of oscillation is shorter compared to that of a linearized model but increasing with time and asymptotically approaching the period of oscillation of the linear damped model. An explicit expression for the period of oscillation has been derived, and it is found to be very accurate....
Experiments on Deflecting & Oscillating Waterjet
Institute of Scientific and Technical Information of China (English)
无
2002-01-01
A new type jet,the oscillating & deflecting jet ,is put forward and its oscillating and deflecting characteristics are investigated.The nozzle of the self-oscillating & deflecting water jet consists of an upstream nozzle,a downstream nozzle,an oscillating chamber and two switches,It is experimentally shown that the deflective angle may reach 9.53 degeree,the generated pressure fluctuation is very regular and the jet can efficiently increase the ability for bradking and cutting by eliminating the water cushion effect associated with a continuous jet.
Unstable oscillators based hyperchaotic circuit
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; G. Mykolaitis, A.;
1999-01-01
A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations in the circ......A simple 4th order hyperchaotic circuit with unstable oscillators is described. The circuit contains two negative impedance converters, two inductors, two capacitors, a linear resistor and a diode. The Lyapunov exponents are presented to confirm hyperchaotic nature of the oscillations...
Nanoscale relaxation oscillator
Zettl, Alexander K.; Regan, Brian C.; Aloni, Shaul
2009-04-07
A nanoscale oscillation device is disclosed, wherein two nanoscale droplets are altered in size by mass transport, then contact each other and merge through surface tension. The device may also comprise a channel having an actuator responsive to mechanical oscillation caused by expansion and contraction of the droplets. It further has a structure for delivering atoms between droplets, wherein the droplets are nanoparticles. Provided are a first particle and a second particle on the channel member, both being made of a chargeable material, the second particle contacting the actuator portion; and electrodes connected to the channel member for delivering a potential gradient across the channel and traversing the first and second particles. The particles are spaced apart a specified distance so that atoms from one particle are delivered to the other particle by mass transport in response to the potential (e.g. voltage potential) and the first and second particles are liquid and touch at a predetermined point of growth, thereby causing merging of the second particle into the first particle by surface tension forces and reverse movement of the actuator. In a preferred embodiment, the channel comprises a carbon nanotube and the droplets comprise metal nanoparticles, e.g. indium, which is readily made liquid.
MULTIPLE OSCILLATION STABILIZING CONTROL.
Energy Technology Data Exchange (ETDEWEB)
YUE,M.; SCHLUETER,R.; AZARM,M.; BARI,R.
2004-07-23
This paper presents a strategy that may be used to guide stabilizing control design for multiple oscillations, which are difficult to control using conventional control design procedures. A multiple oscillation phenomena is observed in an example power system. A local bifurcation and an interarea bifurcation develop in an example power system due to multiple bifurcation parameter variations. The dynamic behaviors of the bifurcating system are complex due to the overlapping of the two different bifurcation subsystems and are shown to be difficult to control. The double bifurcations are studied in this paper and in order to stabilize them, three kind of {mu}-synthesis robust controls are designed, (a) {mu}-synthesis power system stabilizer (MPSS); (b) {mu}-synthesis SVC control (MSVC); and (c) a mixed MPSS/MSVC control. Based on the bifurcation subsystem analysis, the measurement signals and locations of the controls are selected. The control performances of three kind of controls are evaluated and compared. The conclusions are given according to the analysis and time simulation results.
de Cheveigné, Alain; Arzounian, Dorothée
2015-12-01
Objective. Oscillations are an important aspect of brain activity, but they often have a low signal-to-noise ratio (SNR) due to source-to-electrode mixing with competing brain activity and noise. Filtering can improve the SNR of narrowband signals, but it introduces ringing effects that may masquerade as genuine oscillations, leading to uncertainty as to the true oscillatory nature of the phenomena. Likewise, time-frequency analysis kernels have a temporal extent that blurs the time course of narrowband activity, introducing uncertainty as to timing and causal relations between events and/or frequency bands. Approach. Here, we propose a methodology that reveals narrowband activity within multichannel data such as electroencephalography, magnetoencephalography, electrocorticography or local field potential. The method exploits the between-channel correlation structure of the data to suppress competing sources by joint diagonalization of the covariance matrices of narrowband filtered and unfiltered data. Main results. Applied to synthetic and real data, the method effectively extracts narrowband components at unfavorable SNR. Significance. Oscillatory components of brain activity, including weak sources that are hard or impossible to observe using standard methods, can be detected and their time course plotted accurately. The method avoids the temporal artifacts of standard filtering and time-frequency analysis methods with which it remains complementary.
A Matterwave Transistor Oscillator
Caliga, Seth C; Zozulya, Alex A; Anderson, Dana Z
2012-01-01
A triple-well atomtronic transistor combined with forced RF evaporation is used to realize a driven matterwave oscillator circuit. The transistor is implemented using a metalized compound glass and silicon substrate. On-chip and external currents produce a cigar-shaped magnetic trap, which is divided into transistor source, gate, and drain regions by a pair of blue-detuned optical barriers projected onto the magnetic trap through a chip window. A resonant laser beam illuminating the drain portion of the atomtronic transistor couples atoms emitted by the gate to the vacuum. The circuit operates by loading the source with cold atoms and utilizing forced evaporation as a power supply that produces a positive chemical potential in the source, which subsequently drives oscillation. High-resolution in-trap absorption imagery reveals gate atoms that have tunneled from the source and establishes that the circuit emits a nominally mono-energetic matterwave with a frequency of 23.5(1.0) kHz by tunneling from the gate, ...
Physics of bubble oscillations
Energy Technology Data Exchange (ETDEWEB)
Lauterborn, Werner; Kurz, Thomas [Third Physical Institute, University of Goettingen (Germany)
2010-10-01
Bubbles in liquids, soft and squeezy objects made of gas and vapour, yet so strong as to destroy any material and so mysterious as at times turning into tiny light bulbs, are the topic of the present report. Bubbles respond to pressure forces and reveal their full potential when periodically driven by sound waves. The basic equations for nonlinear bubble oscillation in sound fields are given, together with a survey of typical solutions. A bubble in a liquid can be considered as a representative example from nonlinear dynamical systems theory with its resonances, multiple attractors with their basins, bifurcations to chaos and not yet fully describable behaviour due to infinite complexity. Three stability conditions are treated for stable trapping of bubbles in standing sound fields: positional, spherical and diffusional stability. Chemical reactions may become important in that respect, when reacting gases fill the bubble, but the chemistry of bubbles is just touched upon and is beyond the scope of the present report. Bubble collapse, the runaway shrinking of a bubble, is presented in its current state of knowledge. Pressures and temperatures that are reached at this occasion are discussed, as well as the light emission in the form of short flashes. Aspherical bubble collapse, as for instance enforced by boundaries nearby, mitigates most of the phenomena encountered in spherical collapse, but introduces a new effect: jet formation, the self-piercing of a bubble with a high velocity liquid jet. Examples of this phenomenon are given from light induced bubbles. Two oscillating bubbles attract or repel each other, depending on their oscillations and their distance. Upon approaching, attraction may change to repulsion and vice versa. When being close, they also shoot self-piercing jets at each other. Systems of bubbles are treated as they appear after shock wave passage through a liquid and with their branched filaments that they attain in standing sound fields. The N
On The Harmonic Oscillator Group
Lopez, Raquel M; Vega-Guzman, Jose M
2011-01-01
We discuss the maximum kinematical invariance group of the quantum harmonic oscillator from a view point of the Ermakov-type system. The invariance group of generalized driven harmonic oscillator is shown to be isomorphic to the corresponding Schroedinger group of the free particle.
Longitudinal oscillation of launch vehicles
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.
The Wien Bridge Oscillator Family
DEFF Research Database (Denmark)
Lindberg, Erik
2006-01-01
A tutorial in which the Wien bridge family of oscillators is defined and investigated. Oscillators which do not fit into the Barkhausen criterion topology may be designed. A design procedure based on initial complex pole quality factor is reported. The dynamic transfer characteristic...
Lorentz violation and neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Mewes, Matthew [Marquette University, P.O. Box 1881, Milwaukee, WI 53201 (United States)
2011-12-15
Lorentz violation naturally leads to neutrino oscillations and provides an alternative mechanism that may explain current data. This contribution to the proceedings of The XXII International Conference on Neutrino Physics and Astrophysics provides a brief review of possible signals of Lorentz violation in neutrino-oscillation experiments.
Neutrino Oscillations with Nil Mass
Floyd, Edward R
2016-01-01
An alternative neutrino oscillation process is presented as a counterexample for which the neutrino may have nil mass consistent with the standard model. The process is developed in a quantum trajectories representation of quantum mechanics, which has a Hamilton-Jacobi foundation. This process has no need for mass differences between mass eigenstates. Flavor oscillations and $\\bar{\
Solar Neutrino Oscillation - An Overview
Roy, D P
2005-01-01
After a brief summary of the neutrino oscillation formalism and the solar neutrino sources and experiments I discuss the matter effect on solar neutrino oscillation. Then I discuss how the resulting alternative solutions are experimentally resolved in favour of the LMA solution, with particular exphasis on the SK, SNO and KL data.
Hyperchaos in coupled Colpitts oscillators
DEFF Research Database (Denmark)
Cenys, Antanas; Tamasevicius, Arunas; Baziliauskas, Antanas
2003-01-01
The paper suggests a simple solution of building a hyperchaotic oscillator. Two chaotic Colpitts oscillators, either identical or non-identical ones are coupled by means of two linear resistors R-k. The hyperchaotic output signal v(t) is a linear combination, specifically the mean of the individual...
Hyperchaotic system with unstable oscillators
DEFF Research Database (Denmark)
Murali, K.; Tamasevicius, A.; Mykolaitis, G.;
2000-01-01
A simple electronic system exhibiting hyperchaotic behaviour is described. The system includes two nonlinearly coupled 2nd order unstable oscillators, each composed of an LC resonance loop and an amplifier. The system is investigated by means of numerical integration of appropriate differential e...... equations, PSPICE simulations and hardware experiments. The Lyapunov exponents are presented to confirm hyperchaotic mode of the oscillations....
Oscillator With Low Phase Noise
Kleinberg, Leonard L.
1987-01-01
Phase errors cancelled for high frequency stability. Radio-frequency oscillator achieves high stability of frequency through parallel, two-amplifier configuration in which effects cause phase noise tend to cancel each other. Circuit includes two amplifiers with resonating elements, each constitutes part of feedback loop of other. Generate same frequency because each circuit provides other with conditions necessary for oscillation.
Collective supernova neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Mirizzi, Alessandro [Max Planck Institute for Physics, Munich (Germany)
2009-07-01
Neutrinos emitted by core-collapse supernovae (SNe) represent an important laboratory for both particle physics and astrophysics. While propagating in the dense SN environment, they can feel not only the presence of background matter (via ordinary Mikheev-Smirnov-Wolfenstein effects) but also of the gas of neutrinos and antineutrinos (via neutrino-neutrino interaction effects). The neutrino-neutrino interactions appear to modify the flavor evolution of SN neutrinos in a collective way, completely different from the ordinary matter effects. In these conditions, the flavor evolution equations become highly nonlinear, sometimes resulting in surprising phenomena when the entire neutrino system oscillates coherently as a single collective mode. In this talk, I present the recent results on collective supernova neutrino flavor conversions and I discuss about the sensitivity of these effects to the ordering of the neutrino mass spectrum.
Solar neutrino oscillation phenomenology
Indian Academy of Sciences (India)
Srubabati Goswami
2004-02-01
This article summarises the status of the solar neutrino oscillation phenomenology at the end of 2002 in the light of the SNO and KamLAND results. We first present the allowed areas obtained from global solar analysis and demonstrate the preference of the solar data towards the large-mixing-angle (LMA) MSW solution. A clear confirmation in favour of the LMA solution comes from the KamLAND reactor neutrino data. the KamLAND spectral data in conjunction with the global solar data further narrows down the allowed LMA region and splits it into two allowed zones - a low $ m^{2}$ region (low-LMA) and high $ m^{2}$ region (high-LMA). We demonstrate through a projected analysis that with an exposure of 3 kton-year (kTy) KamLAND can remove this ambiguity.
Coronal Waves and Oscillations
Directory of Open Access Journals (Sweden)
Nakariakov Valery M.
2005-07-01
Full Text Available Wave and oscillatory activity of the solar corona is confidently observed with modern imaging and spectral instruments in the visible light, EUV, X-ray and radio bands, and interpreted in terms of magnetohydrodynamic (MHD wave theory. The review reflects the current trends in the observational study of coronal waves and oscillations (standing kink, sausage and longitudinal modes, propagating slow waves and fast wave trains, the search for torsional waves, theoretical modelling of interaction of MHD waves with plasma structures, and implementation of the theoretical results for the mode identification. Also the use of MHD waves for remote diagnostics of coronal plasma - MHD coronal seismology - is discussed and the applicability of this method for the estimation of coronal magnetic field, transport coefficients, fine structuring and heating function is demonstrated.
Coupled oscillators on evolving networks
Singh, R. K.; Bagarti, Trilochan
2016-12-01
In this work we study coupled oscillators on evolving networks. We find that the steady state behavior of the system is governed by the relative values of the spread in natural frequencies and the global coupling strength. For coupling strong in comparison to the spread in frequencies, the system of oscillators synchronize and when coupling strength and spread in frequencies are large, a phenomenon similar to amplitude death is observed. The network evolution provides a mechanism to build inter-oscillator connections and once a dynamic equilibrium is achieved, oscillators evolve according to their local interactions. We also find that the steady state properties change by the presence of additional time scales. We demonstrate these results based on numerical calculations studying dynamical evolution of limit-cycle and van der Pol oscillators.
Oscillating nonlinear acoustic shock waves
DEFF Research Database (Denmark)
Gaididei, Yuri; Rasmussen, Anders Rønne; Christiansen, Peter Leth
2016-01-01
We investigate oscillating shock waves in a tube using a higher order weakly nonlinear acoustic model. The model includes thermoviscous effects and is non isentropic. The oscillating shock waves are generated at one end of the tube by a sinusoidal driver. Numerical simulations show...... that at resonance a stationary state arise consisting of multiple oscillating shock waves. Off resonance driving leads to a nearly linear oscillating ground state but superimposed by bursts of a fast oscillating shock wave. Based on a travelling wave ansatz for the fluid velocity potential with an added 2'nd order...... polynomial in the space and time variables, we find analytical approximations to the observed single shock waves in an infinitely long tube. Using perturbation theory for the driven acoustic system approximative analytical solutions for the off resonant case are determined....
Photoacoustic elastic oscillation and characterization.
Gao, Fei; Feng, Xiaohua; Zheng, Yuanjin
2015-08-10
Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ratio beyond optical absorption only, which is experimentally demonstrated in this paper.
Photoacoustic elastic oscillation and characterization
Gao, Fei; Zheng, Yuanjin
2014-01-01
Photoacoustic imaging and sensing have been studied extensively to probe the optical absorption of biological tissue in multiple scales ranging from large organs to small molecules. However, its elastic oscillation characterization is rarely studied and has been an untapped area to be explored. In literature, photoacoustic signal induced by pulsed laser is commonly modelled as a bipolar "N-shape" pulse from an optical absorber. In this paper, the photoacoustic damped oscillation is predicted and modelled by an equivalent mass-spring system by treating the optical absorber as an elastic oscillator. The photoacoustic simulation incorporating the proposed oscillation model shows better agreement with the measured signal from an elastic phantom, than conventional photoacoustic simulation model. More interestingly, the photoacoustic damping oscillation effect could potentially be a useful characterization approach to evaluate biological tissue's mechanical properties in terms of relaxation time, peak number and ra...
Directory of Open Access Journals (Sweden)
Y. Abedini
2000-06-01
Full Text Available This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillations of stars was studied by Cowling and others. They classified the oscillation modes of the stars into acoustic and gravity modes on the basis of their driving forces. These are pressure and buoyancy forces respectively. The earliest measurements for the period of the free oscillations of the Earth was made by Benyove from a study of Kamchathca earthquake. Since then, the Geophysicists have been trying to provide a theoretical basis for these measurements. Recently, the theory concerning oscillations of celestial fluids is extended by Sobouti to include the possible oscillations of the Earthlike bodies. Using the same technique, we study the free oscillations of a spherically symmetric, non-rotating and elastic model for the Earth. We used the actual data of the Earths interior structure in our numerical calculations. Numerical results show that there exist three distinct oscillation modes namely acoustic, gravity and toroidal modes. These modes are driven by pressure, buoyancy and shear forces respectively. The shear force is due to the elastic properties of the solid part of the Earth. Our numerical results are consistent with the seismic data recorded from earthquake measurements.
Polynomially deformed oscillators as k-bonacci oscillators
Gavrilik, A M
2009-01-01
A family of multi-parameter, polynomially deformed oscillators (PDOs) given by polynomial structure function \\phi(n) is studied from the viewpoint of being (or not) in the class of Fibonacci oscillators. These obey the Fibonacci relation/property (FR/FP) meaning that the n-th level energy E_n is given linearly, with real coefficients, by the two preceding ones E_{n-1}, E_{n-2}. We first prove that the PDOs do not fall in the Fibonacci class. Then, three different paths of generalizing the usual FP are developed for these oscillators: we prove that the PDOs satisfy respective k-term generalized Fibonacci (or "k-bonacci") relations; for these same oscillators we examine two other generalizations of the FR, the inhomogeneous FR and the "quasi-Fibonacci" relation. Extended families of deformed oscillators are studied too: the (q;\\mu)-oscillator with \\phi(n) quadratic in the basic q-number [n]_q is shown to be Tribonacci one, while the (p,q;\\mu)-oscillators with \\phi(n) quadratic (cubic) in the p,q-number [n]_{p,q...
Hybrid microelectronic technology
Moran, P.
Various areas of hybrid microelectronic technology are discussed. The topics addressed include: basic thick film processing, thick film pastes and substrates, add-on components and attachment methods, thin film processing, and design of thick film hybrid circuits. Also considered are: packaging hybrid circuits, automating the production of hybrid circuits, application of hybrid techniques, customer's view of hybrid technology, and quality control and assurance in hybrid circuit production.
Early Oscillation Detection for DC/DC Converter Fault Diagnosis
Wang, Bright L.
2011-01-01
The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.
A theory of generalized Bloch oscillations.
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.
CP-Violation in Neutrino Oscillations from EC/{beta}{sup +} decaying ion beams
Energy Technology Data Exchange (ETDEWEB)
Espinoza, Catalina [Centre for Theoretical Particle Physics, IST, Technical University of Lisbon, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal)
2012-08-15
We discuss the separation of unknown neutrino properties by means of the energy dependence of the oscillation probability and we consider an hybrid setup which combines the electron capture and the {beta}{sup +} decay from the same radioactive proton-rich ion with the same boost. We conclude that the combination of the two decay channels, with different neutrino energies, achieves remarkable results.
Diverse routes to oscillation death in a coupled oscillator system
Suárez-Vargas, José J.; González, Jorge A.; Stefanovska, Aneta; McClintock, Peter V. E.
2010-01-01
We study oscillation death (OD) in a well-known coupled-oscillator system that has been used to model cardiovascular phenomena. We derive exact analytic conditions that allow the prediction of OD through the two known bifurcation routes, in the same model, and for different numbers of coupled oscillators. Our exact analytic results enable us to generalize OD as a multiparameter-sensitive phenomenon. It can be induced, not only by changes in couplings, but also by changes in the oscillator frequencies or amplitudes. We observe synchronization transitions as a function of coupling and confirm the robustness of the phenomena in the presence of noise. Numerical and analogue simulations are in good agreement with the theory. PMID:20823952
Gravitational Wave - Gauge Field Oscillations
Caldwell, R R; Maksimova, N A
2016-01-01
Gravitational waves propagating through a stationary gauge field transform into gauge field waves and back again. When multiple families of flavor-space locked gauge fields are present, the gravitational and gauge field waves exhibit novel dynamics. At high frequencies, the system behaves like coupled oscillators in which the gravitational wave is the central pacemaker. Due to energy conservation and exchange among the oscillators, the wave amplitudes lie on a multi-dimensional sphere, reminiscent of neutrino flavor oscillations. This phenomenon has implications for cosmological scenarios based on flavor-space locked gauge fields.
Oscillating solitons in nonlinear optics
Indian Academy of Sciences (India)
Lin Xiao-Gang; Liu Wen-Jun; Lei Ming
2016-03-01
Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota’s bilinear method. The bilinear forms and analytic soliton solutions are derived, and the relevant properties and features of oscillating solitons are illustrated. Oscillating solitons are controlled by the reciprocal of the group velocity and Kerr nonlinearity. Results of this paper will be valuable to the study of dispersion-managed optical communication system and mode-locked fibre lasers.
Forced synchronization of quasiperiodic oscillations
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.
Collective oscillations in a plasma
Akhiezer, A I; Polovin, R V; ter Haar, D
2013-01-01
International Series of Monographs in Natural Philosophy: Collective Oscillations in a Plasma, Volume 7 presents specific topics within the general field of radio waves propagation. This book contains five chapters that address the theory of linear oscillations in a plasma, the spectra of the eigen oscillations, and the mechanism of high-frequency heating. The opening chapters deal with the self-consistent fields; development of initial perturbation; dispersion permittivity tensor of a plasma in a magnetic field; effect of thermal motion of particles on low-frequency resonances; excitation of
Active optomechanics through relaxation oscillations
Princepe, Debora; Frateschi, Newton
2014-01-01
We propose an optomechanical laser based on III-V compounds which exhibits self-pulsation in the presence of a dissipative optomechanical coupling. In such a laser cavity, radiation pressure drives the mechanical degree of freedom and its back-action is caused by the mechanical modulation of the cavity loss rate. Our numerical analysis shows that even in a wideband gain material, such dissipative coupling couples the mechanical oscillation with the laser relaxation oscillations process. Laser self-pulsation is observed for mechanical frequencies below the laser relaxation oscillation frequency under sufficiently high optomechanical coupling factor.
Chromosome oscillations in mitosis
Campas, Otger
2008-03-01
Successful cell division necessitates a tight regulation of chromosome movement via the activity of molecular motors. Many of the key players at the origin of the forces generating the motion have been identified, but their spatial and temporal organization remains elusive. In animal cells, chromosomes periodically switch between phases of movement towards and away from the pole. This characteristic oscillatory behaviour cannot be explained by the current models of chromosome positioning and congression. We perform a self-contained theoretical analysis in which the motion of mono-oriented chromosomes results from the competition between the activity of the kinetochore and chromokinesin motors on the chromosome arms. Our analysis, consistent with the available experimental data, proposes that the interplay between the aster-like morphology of the spindle and the collective kinetics of molecular motors is at the origin of chromosome oscillations, positioning and congression. It provides a natural explanation for the so-called chromosome directional instability and for the mechanism by which chromosomes sense their position in space. In addition, we estimate the in vivo velocity of chromokinesins at vanishing load and propose new experiments to assess the mechanism at the origin of chromosome movement in cell division.
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.
Oscillations in Mathematical Biology
1983-01-01
The papers in this volume are based on talks given at a one day conference held on the campus of Adelphi University in April 1982. The conference was organized with the title "Oscillations in Mathematical Biology;" however the speakers were allowed considerable latitutde in their choice of topics. In the event, the talks all concerned the dynamics of non-linear systems arising in biology so that the conference achieved a good measure of cohesion. Some of the speakers cho~e not to submit a manuscript for these proceedings, feeling that their material was too conjectural to be committed to print. Also the paper of Rinzel and Troy is a distillation of the two separate talks that the authors gave. Otherwise the material reproduces the conference proceedings. The conference was made possible by the generous support of the Office of the Dean of the College of Arts and Sciences at Adelphi. The bulk of the organization of the conference was carried out by Dr. Ronald Grisell whose energy was in large measure responsib...
Osborne, Andrew G
2016-01-01
Under the right conditions, self sustaining fission waves can form in fertile nuclear materials. These waves result from the transport and absorption of neutrons and the resulting production of fissile isotopes. When these fission, additional neutrons are produced and the chain reaction propagates until it is poisoned by the buildup of fission products. It is typically assumed that fission waves are soliton-like and self stabilizing. However, we show that in uranium, coupling of the neutron field to the 239U->239Np->239Pu decay chain can lead to a Hopf bifurcation. The fission reaction then ramps up and down, along with the wave velocity. The critical driver for the instability is a delay, caused by the half-life of 239U, between the time evolution of the neutron field and the production of 239Pu. This allows the 239Pu to accumulate and burn out in a self limiting oscillation that is characteristic of a Hopf bifurcation. Time dependent results are obtained using a numerical implementation of a reduced order r...
Handschuh, Robert F. (Inventor); Roberts, Gary D. (Inventor)
2016-01-01
A hybrid gear consisting of metallic outer rim with gear teeth and metallic hub in combination with a composite lay up between the shaft interface (hub) and gear tooth rim is described. The composite lay-up lightens the gear member while having similar torque carrying capability and it attenuates the impact loading driven noise/vibration that is typical in gear systems. The gear has the same operational capability with respect to shaft speed, torque, and temperature as an all-metallic gear as used in aerospace gear design.
DEFF Research Database (Denmark)
has turned out as a major focus of European education and training policies and certainly is a crucial principle underlying the European Qualifications Framework (EQF). In this context, «hybrid qualifications» (HQ) may be seen as an interesting approach to tackle these challenges as they serve «two...... masters», i.e. by producing skills for the labour market and enabling individuals to progress more or less directly to higher education. The specific focus of this book is placed on conditions, structures and processes which help to combine VET with qualifications leading into higher education...
Gamma Oscillations and Visual Binding
Robinson, Peter A.; Kim, Jong Won
2006-03-01
At the root of visual perception is the mechanism the brain uses to analyze features in a scene and bind related ones together. Experiments show this process is linked to oscillations of brain activity in the 30-100 Hz gamma band. Oscillations at different sites have correlation functions (CFs) that often peak at zero lag, implying simultaneous firing, even when conduction delays are large. CFs are strongest between cells stimulated by related features. Gamma oscillations are studied here by modeling mm-scale patchy interconnections in the visual cortex. Resulting predictions for gamma responses to stimuli account for numerous experimental findings, including why oscillations and zero-lag synchrony are associated, observed connections with feature preferences, the shape of the zero-lag peak, and variations of CFs with attention. Gamma waves are found to obey the Schroedinger equation, opening the possibility of cortical analogs of quantum phenomena. Gamma instabilities are tied to observations of gamma activity linked to seizures and hallucinations.
Atmospheric Neutrino Oscillations in Antares
Energy Technology Data Exchange (ETDEWEB)
Brunner, J.
2013-04-15
The data taken with the ANTARES neutrino telescope from 2007 to 2010, a total live time of 863 days, are used to measure the oscillation parameters of atmospheric neutrinos. Muon tracks are reconstructed with energies as low as 20 GeV. Neutrino oscillations will cause a suppression of vertical upgoing muon neutrinos of such energies crossing the Earth. The parameters determining the oscillation of atmospheric neutrinos are extracted by fitting the event rate as a function of the ratio of the estimated neutrino energy and reconstructed flight path through the Earth. Measurement contours of the oscillation parameters in a two-flavour approximation are derived. Assuming maximum mixing, a mass difference of Δm{sub 32}{sup 2}=(3.1±0.9)⋅10{sup −3}eV{sup 2} is obtained, in good agreement with the world average value.
Strongly nonlinear oscillators analytical solutions
Cveticanin, Livija
2014-01-01
This book provides the presentation of the motion of pure nonlinear oscillatory systems and various solution procedures which give the approximate solutions of the strong nonlinear oscillator equations. The book presents the original author’s method for the analytical solution procedure of the pure nonlinear oscillator system. After an introduction, the physical explanation of the pure nonlinearity and of the pure nonlinear oscillator is given. The analytical solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter is considered. Special attention is given to the one and two mass oscillatory systems with two-degrees-of-freedom. The criteria for the deterministic chaos in ideal and non-ideal pure nonlinear oscillators are derived analytically. The method for suppressing chaos is developed. Important problems are discussed in didactic exercises. The book is self-consistent and suitable as a textbook for students and also for profess...
Matter Effects On Neutrino Oscillations
Gordon, Michael
An introduction to neutrino oscillations in vacuum is presented, followed by a survey of various techniques for obtaining either exact or approximate expressions for numu → nue oscillations in matter. The method developed by Arafune, Koike, and Sato uses a perturbative analysis to find an approximation for the evolution operator. The method used by Freund yields an approximate oscillation probability by diagonalizing the Hamiltonian, finding the eigenvalues and eigenvectors, and then using those to find modified mixing angles with the matter effect taken into account. The method devised by Mann, Kafka, Schneps, and Altinok produces an exact expression for the oscillation by determining explicitly the evolution operator. These methods are compared to each other using the T2K, MINOS, NOnuA, and LBNE parameters.
Oscillations of a chemical garden
Pantaleone, J.; Toth, A.; Horvath, D.; Rother McMahan, J.; Smith, R.; Butki, D.; Braden, J.; Mathews, E.; Geri, H.; Maselko, J.
2008-04-01
When soluble metal salts are placed in a silicate solution, chemical gardens grow. These gardens are treelike structures formed of long, thin, hollow tubes. Here we study one particular case: a calcium nitrate pellet in a solution of sodium trisilicate. We observe that tube growth results from a relaxation oscillation. The average period and the average growth rate are approximately constant for most of the structures growth. The period does fluctuate from cycle to cycle, with the oscillation amplitude proportional to the period. Based on our observations, we develop a model of the relaxation oscillations which calculates the average oscillation period and the average tube radius in terms of fundamental membrane parameters. We also propose a model for the average tube growth rate. Predictions are made for future experiments.
Global Analysis of Neutrino Oscillation
Goswami, S; Choubey, S; Goswami, Srubabati; Bandyopadhyay, Abhijit; Choubey, Sandhya
2005-01-01
We present the constraints on neutrino oscillation parameters $\\Delta m^2_{\\odot}$ and $\\theta_{\\odot}$ governing the solar neutrino oscillations from two generation analysis of solar and KamLAND data. We include the latest 766.3 ton year KamLAND data in our analysis. We also present the allowed values of parameters $\\Delta m^2_{atm}$ and $\\sin^2\\theta_{atm}$ from two generation oscillation analysis of SuperKamiokande atmospheric and K2K data. For both cases we discuss the precision achieved in the present set of experiments and also how the precision can be improved in future. We also obtain the bounds on $\\theta_{13}$ from three generation analysis of global oscillation data. We emphasise on the roles played by different data sets in constraining the allowed parameter ranges.
Global Analysis of Neutrino Oscillation
Energy Technology Data Exchange (ETDEWEB)
Goswami, Srubabati [Harish-Chandra Research Institute, Chhatnag Road, Jhusi, Allahabad 211 019 (India); Bandyopadhyay, Abhijit [Theory Group, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Calcutta 700 064 (India); Choubey, Sandhya [INFN, Sezione di Trieste and Scuola Internazionale Superiore di Studi Avanzati, I-34014, Trieste (Italy)
2005-06-15
We present the constraints on neutrino oscillation parameters {delta}m{sub -}bar {sup 2} and {theta}{sub -}bar governing the solar neutrino oscillations from two generation analysis of solar and KamLAND data. We include the latest 766.3 ton year KamLAND data in our analysis. We also present the allowed values of parameters {delta}m{sub atm}{sup 2} and sin{sup 2}{theta}{sub atm} from two generation oscillation analysis of SuperKamiokande atmospheric and K2K data. For both cases we discuss the precision achieved in the present set of experiments and also how the precision can be improved in future. We also obtain the bounds on {theta}{sub 13} from three generation analysis of global oscillation data. We emphasise on the roles played by different data sets in constraining the allowed parameter ranges.
Strong nonlinear oscillators analytical solutions
Cveticanin, Livija
2017-01-01
This book outlines an analytical solution procedure of the pure nonlinear oscillator system, offering a solution for free and forced vibrations of the one-degree-of-freedom strong nonlinear system with constant and time variable parameter. Includes exercises.
Matrix Theory of Small Oscillations
Chavda, L. K.
1978-01-01
A complete matrix formulation of the theory of small oscillations is presented. Simple analytic solutions involving matrix functions are found which clearly exhibit the transients, the damping factors, the Breit-Wigner form for resonances, etc. (BB)
Oscillations of thick accretion discs
Energy Technology Data Exchange (ETDEWEB)
Jaroszynski, M.
1986-06-15
The non-axisymmetric oscillations of polytropic, ideal fluid tori rotating in the external gravitational field of a point mass are investigated both numerically and analytically. Normal modes of oscillations are found; their classification into 'radial', 'p', 'g' and 'f' modes is done in analogy to the stellar case. The non-discrete spectrum of modes which are neutral in the limit of axisymmetric perturbations is also present.
Harmonic Oscillators and Elementary Particles
Sobouti, Y
2016-01-01
Two dynamical systems with same symmetry should have features in common, and as far as their shared symmetry is concerned, one may represent the other. The three light quark constituents of the hadrons, a) have an approximate flavor SU(3) symmetry, b) have an exact color SU(3) symmetry, and c) as spin 1/2 particles, have a Lorentz SO(3,1) symmetry. So does a 3D harmonic oscillator. a) Its Hamiltonian has the SU(3) symmetry, breakable if the 3 fundamental modes of oscillation are not identical. b) The 3 directions of oscillation have the permutation symmetry. This enables one to create three copies of unbreakable SU(3) symmetry for each mode of the oscillation, and mimic the color of the elementary particles. And c) The Lagrangian of the 3D oscillator has the SO(3,1) symmetry. This can be employed to accommodate the spin of the particles. In this paper we draw up a one-to-one correspondence between the eigen modes of the Poisson bracket operator of the 3D oscillator and the flavor multiplets of the particles, ...
On the nonlinear modeling of ring oscillators
Elwakil, Ahmed S.
2009-06-01
We develop higher-order nonlinear models of three-stage and five-stage ring oscillators based on a novel inverter model. The oscillation condition and oscillation frequency are derived and compared to classical linear model analysis. Two important special cases for five-stage ring oscillators are also studied. Numerical simulations are shown. © 2009 World Scientific Publishing Company.
Magnetically Coupled Magnet-Spring Oscillators
Donoso, G.; Ladera, C. L.; Martin, P.
2010-01-01
A system of two magnets hung from two vertical springs and oscillating in the hollows of a pair of coils connected in series is a new, interesting and useful example of coupled oscillators. The electromagnetically coupled oscillations of these oscillators are experimentally and theoretically studied. Its coupling is electromagnetic instead of…
DEFF Research Database (Denmark)
Braüner, Torben
2011-01-01
Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area.......Intuitionistic hybrid logic is hybrid modal logic over an intuitionistic logic basis instead of a classical logical basis. In this short paper we introduce intuitionistic hybrid logic and we give a survey of work in the area....
Continuity Controlled Hybrid Automata
Bergstra, J. A.; Middelburg, C.A.
2004-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of hybrid automata as timed transition systems. We also relate the synchronized product operator on hybrid automata to the parallel composition operator of the process algebra. It turns out that the f...
Thermomechanical Testing Techniques for Microcircuits.
1975-05-01
Novolac. (B) Type 2 epoxy is an Anhydride Cured, Bisphenol-A, epoxy TABLE 1-1 Package Classification By Vendor 1-5 analysis on the dual-in-line...C to 125°C), Vendor 2. This nomenclature , derived from Table 1-2, is carried throughout: this and subsequent sections. 4.6.2 Plastic Results
AMYGDALA MICROCIRCUITS CONTROLLING LEARNED FEAR
Duvarci, Sevil; Pare, Denis
2014-01-01
We review recent work on the role of intrinsic amygdala networks in the regulation of classically conditioned defensive behaviors, commonly known as conditioned fear. These new developments highlight how conditioned fear depends on far more complex networks than initially envisioned. Indeed, multiple parallel inhibitory and excitatory circuits are differentially recruited during the expression versus extinction of conditioned fear. Moreover, shifts between expression and extinction circuits involve coordinated interactions with different regions of the medial prefrontal cortex. However, key areas of uncertainty remain, particularly with respect to the connectivity of the different cell types. Filling these gaps in our knowledge is important because much evidence indicates that human anxiety disorders results from an abnormal regulation of the networks supporting fear learning. PMID:24908482
A theory of generalized Bloch oscillations
DEFF Research Database (Denmark)
Duggen, Lars; Lew Yan Voon, L. C.; Lassen, Benny;
2016-01-01
Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact cal...... oscillations. We stipulate that the presented theory of generalized Bloch oscillations can be extended to other systems such as acoustics and photonics.......Bloch oscillations of electrons are shown to occur for cases when the energy spectrum does not consist of the traditional evenly-spaced ladders and the potential gradient does not result from an external electric field. A theory of such generalized Bloch oscillations is presented and an exact...... calculation is given to confirm this phenomenon. Our results allow for a greater freedom of design for experimentally observing Bloch oscillations. For strongly coupled oscillator systems displaying Bloch oscillations, it is further demonstrated that reordering of oscillators leads to destruction of Bloch...
Spin induced gigahertz polarization oscillations in vertical-cavity surface-emitting laser devices
Li, M. Y.; Jaehme, H.; Soldat, H.; Gerhardt, N. C.; Hofmann, M. R.; Ackemann, T.
2011-03-01
Spin-controlled vertical-cavity surface-emitting lasers (VCSELs) have been intensively studied in recent years because of the low threshold feasibility and the nonlinearity above threshold, which make spin-VCSELs very promising for spintronic devices. Here we investigate the circular polarization dynamics of VCSELs on a picosecond time scale after pulsed optical spin injection at room temperature. A hybrid excitation technique combining continuous-wave (cw) unpolarized electrical excitation slightly above threshold and pulsed polarized optical excitation is applied. The experimental results demonstrate ultrafast circular polarization oscillations with a frequency of about 11 GHz. The oscillations last inside the first undulation of the intensity relaxation oscillations. Via theoretical calculations based on a rate equation model we analyze these oscillations as well as the underlying physical mechanisms.
Sun, Jitao; Lin, Hai
2008-09-01
This paper investigates the stationary oscillation for an impulsive delayed system which represents a class of nonlinear hybrid systems. First, a new concept of S-stability is introduced for nonlinear impulsive delayed systems. Based on this new concept and fixed point theorem, the relationship between S-stability and stationary oscillation (i.e., existence, uniqueness and global stability of periodic solutions) for the nonlinear impulsive delayed system is explored. It is shown that the nonlinear impulsive delayed system has a stationary oscillation if the system is S-stable. Second, an easily verifiable sufficient condition is then obtained for stationary oscillations of nonautonomous neural networks with both time delays and impulses by using the new criterion. Finally, an illustrative example is given to demonstrate the effectiveness of the proposed method.
An analysis of the autodyne effect of oscillators with linear frequency modulation
Votoropin, S. D.; Noskov, V. Ya.; Smolskiy, S. M.
2008-06-01
General equations are obtained for the autodyne response in the case of an arbitrary frequency modulation both over the active element bias circuit and voltage variation on the voltage-dependent capacitor (varicap). The results of investigation of an autodyne oscillator with linear frequency modulation following the antisymmetric and symmetric saw-tooth function are presented, with the oscillator being affected by its own reflected radiation. Special features of self-oscillations of such autodynes are considered, with the aim to improve their characteristics and extend the functional capabilities of short-range autodyne radars. The experimental results obtained for the TIGEL 08FM oscillator module manufactured using a hybrid-integral technology on the basis of a mm-range Gunn diode are reported.
Modelling of low-current self-generated oscillations in a hollow cathode discharge
Donko, Z
1999-01-01
Low-current self-generated oscillations in a rectangular hollow cathode discharge in helium gas were investigated experimentally and by means of a two-dimensional self-consistent hybrid model. The model combines Monte Carlo simulation of the motion of fast electrons and a fluid description of slow electrons and positive ions. The low-frequency (<=20 kHz) oscillations were found to arise as an effect of the interaction of the gas discharge and the external electric circuit - consisting of a stable voltage source, a series resistor and a capacitor formed by the discharge electrodes. Good agreement was found between the experimentally observed and calculated oscillation frequency and current wave forms. Beside these characteristics the modelling also made it possible to calculate the time dependence of numerous other discharge characteristics (e.g. electron multiplication, ion density, potential distribution) and provided detailed insight into the mechanism of oscillations. The advantage of the present model ...
Self-filtering oscillations in carbon nanotube hetero-junctions.
Scarpa, F; Narojczyk, J W; Wojciechowski, K W; Inman, D J
2011-11-18
We evaluate the vibrational properties of single-wall carbon nanotube (SWCNT) hetero-junction (HJ) oscillators using a hybrid atomistic-continuum approach validated by molecular mechanics/molecular dynamics simulations. The SWCNT-HJs show a broken symmetry topology of their mode shapes, with striction effects caused on the bending and radial modes by the combined effect of the HJ and the tube with the thinner radius. The single-wall nanotube HJs also show selective mass sensing properties based solely on the geometry and type of the boundary conditions of the specific nanostructure. This unusual behaviour has not been observed so far in classical SWCNT systems.
A hybrid model for the computationally-efficient simulation of the cerebellar granular layer
Directory of Open Access Journals (Sweden)
Anna eCattani
2016-04-01
Full Text Available The aim of the present paper is to efficiently describe the membrane potential dynamics of neural populations formed by species having a high density difference in specific brain areas. We propose a hybrid model whose main ingredients are a conductance-based model (ODE system and its continuous counterpart (PDE system obtained through a limit process in which the number of neurons confined in a bounded region of the brain tissue is sent to infinity. Specifically, in the discrete model, each cell is described by a set of time-dependent variables, whereas in the continuum model, cells are grouped into populations that are described by a set of continuous variables.Communications between populations, which translate into interactions among the discrete and the continuous models, are the essence of the hybrid model we present here. The cerebellum and cerebellum-like structures show in their granular layer a large difference in the relative density of neuronal species making them a natural testing ground for our hybrid model. By reconstructing the ensemble activity of the cerebellar granular layer network and by comparing our results to a more realistic computational network, we demonstrate that our description of the network activity, even though it is not biophysically detailed, is still capable of reproducing salient features of neural network dynamics. Our modeling approach yields a significant computational cost reduction by increasing the simulation speed at least $270$ times. The hybrid model reproduces interesting dynamics such as local microcircuit synchronization, traveling waves, center-surround and time-windowing.
Regenerative oscillation and four-wave mixing in graphene optoelectronics
Gu, Tingyi; Yang, Xiaodong; McMillian, James F; van der Zander, Arend; Yu, Min-bing; Lo, Guo-Qiang; Kwong, Dim-Lee; Hone, James; Wong, Chee-Wei
2012-01-01
The unique linear and massless band structure of graphene, in a purely two-dimensional Dirac fermionic structure, have led to intense research spanning from condensed matter physics to nanoscale device applications covering the electrical, thermal, mechanical and optical domains. Here we report three consecutive first-observations in graphene-silicon hybrid optoelectronic devices: (1) ultralow power resonant optical bistability; (2) self-induced regenerative oscillations; and (3) coherent four-wave mixing, all at a few femtojoule cavity recirculating energies. These observations, in comparison with control measurements with solely monolithic silicon cavities, are enabled only by the dramatically-large and chi(3) nonlinearities in graphene and the large Q/V ratios in wavelength-localized photonic crystal cavities. These results demonstrate the feasibility and versatility of hybrid two-dimensional graphene-silicon nanophotonic devices for next-generation chip-scale ultrafast optical communications, radio-freque...
Regulation Mechanisms of Stomatal Oscillation
Institute of Scientific and Technical Information of China (English)
Hui-Min YANG; Jian-Hua ZHANG; Xiao-Yan ZHANG
2005-01-01
Stomata function as the gates between the plant and the atmospheric environment. Stomatal movement, including stomatal opening and closing, controls CO2 absorption as the raw material for photosynthesis and water loss through transpiration. How to reduce water loss and maintain enough CO2 absorption has been an interesting research topic for some time. Simple stomatal opening may elevate CO2 absorption,but, in the meantime, promote the water loss, whereas simple closing of stomatal pores may reduce both water loss and CO2 absorption, resulting in impairment of plant photosynthesis. Both processes are not economical to the plant. As a special rhythmic stomatal movement that usually occurs at smaller stomatal apertures, stomatal oscillation can keep CO2 absorption at a sufficient level and reduce water loss at the same time, suggesting a potential improvement in water use efficiency. Stomatal oscillation is usually found after a sudden change in one environmental factor in relatively constant environments. Many environmental stimuli can induce stomatal oscillation. It appears that, at the physiological level, feedback controls are involved in stomatal oscillation. At the cellular level, possibly two different patterns exist: (i) a quicker responsive pattern; and (ii) a slower response. Both involve water potential changes and water channel regulation, but the mechanisms of regulation of the two patterns are different. Some evidence suggests that the regulation of water channels may play a vital and primary role in stomatal oscillation. The present review summarizes studies on stomatal oscillation and concludes with some discussion regarding the mechanisms of regulation of stomatal oscillation.
Directory of Open Access Journals (Sweden)
A. Esposito
2016-07-01
Full Text Available We propose a new interpretation of the neutral and charged X,Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules but rather a manifestation of the interplay between the two. While meson molecules need a negative or zero binding energy, its counterpart for h-tetraquarks is required to be positive. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs0π± channel by the D0 Collaboration and the negative result presented subsequently by the LHCb Collaboration are understood in this scheme, together with a considerable portion of available data on X,Z particles. Considerations on a state with the same quantum numbers as the X(5568 are also made.
Esposito, A.; Polosa, A.D.
2016-01-01
We propose a new interpretation of the neutral and charged X, Z exotic hadron resonances. Hybridized-tetraquarks are neither purely compact tetraquark states nor bound or loosely bound molecules. The latter would require a negative or zero binding energy whose counterpart in h-tetraquarks is a positive quantity. The formation mechanism of this new class of hadrons is inspired by that of Feshbach metastable states in atomic physics. The recent claim of an exotic resonance in the Bs pi+- channel by the D0 collaboration and the negative result presented subsequently by the LHCb collaboration are understood in this scheme, together with a considerable portion of available data on X, Z particles. Considerations on a state with the same quantum numbers as the X(5568) are also made.
Structural properties of maize hybrids established by infrared spectra
Directory of Open Access Journals (Sweden)
Radenović Čedomir N.
2015-01-01
Full Text Available This paper discusses the application of the infrared (IR spectroscopy method for determination of structural properties of maize hybrid grains. The IR spectrum of maize grain has been registered in the following hybrids: ZP 341, ZP 434 and ZP 505. The existence of spectral bands varying in both number and intensity, as well as their shape, frequency and kinetics have been determined. They have been determined by valence oscillations and deformation oscillations of the following organic compounds: alkanes, alkenes, alkynes, amides, alcohols, ethers, carboxylic acids, esters and aldehydes and ketones, characteristic for biogenic compounds such as carbohydrates, proteins and lipids. In this way, possible changes in the grain structure of observed maize hybrids could be detected.
Magnetometer Based on Optoelectronic Microwave Oscillator
Maleki, Lute; Strekalov, Dmitry; Matsko, Andrey
2005-01-01
proposed instrument, intended mainly for use as a magnetometer, would include an optoelectronic oscillator (OEO) stabilized by an atomic cell that could play the role of a magnetically tunable microwave filter. The microwave frequency would vary with the magnetic field in the cell, thereby providing an indication of the magnetic field. The proposed magnetometer would offer a combination of high accuracy and high sensitivity, characterized by flux densities of less than a picotesla. In comparison with prior magnetometers, the proposed magnetometer could, in principle, be constructed as a compact, lightweight instrument: It could fit into a package of about 10 by 10 by 10 cm and would have a mass <0.5 kg. As described in several prior NASA Tech Briefs articles, an OEO is a hybrid of photonic and electronic components that generates highly spectrally pure microwave radiation, and optical radiation modulated by the microwave radiation, through direct conversion between laser light and microwave radiation in an optoelectronic feedback loop. As used here, "atomic cell" signifies a cell containing a vapor, the constituent atoms of which can be made to undergo transitions between quantum states, denoted hyperfine levels, when excited by light in a suitable wavelength range. The laser light must be in this range. The energy difference between the hyperfine levels defines the microwave frequency. In the proposed instrument (see figure), light from a laser would be introduced into an electro-optical modulator (EOM). Amplitude-modulated light from the exit port of the EOM would pass through a fiber-optic splitter having two output branches. The light in one branch would be sent through an atomic cell to a photodiode. The light in the other branch would constitute the microwave-modulated optical output. Part of the light leaving the atomic cell could also be used to stabilize the laser at a frequency in the vicinity of the desired hyperfine or other quantum transition. The
El Nino Southern Oscillation as Sporadic Oscillations between Metastable States
Institute of Scientific and Technical Information of China (English)
无
2011-01-01
The main objective of this article is to establish a new mechanism of ENSO,as a self-organizing and self-excitation system,with two highly coupled processes.The first is the oscillation between the two metastable warm（El Ni（？）o phase） and cold events（La Ni（？）a phase）,and the second is the spatiotemporal oscillation of the sea surface temperature（SST） field.The symbiotic interplay between these two processes gives rises the climate variability associated with the ENSO,leads to both the random and deterministic features of the ENSO,and defines a new natural feedback mechanism,which drives the sporadic oscillation of the ENSO.The new mechanism is rigorously derived using a dynamic transition theory developed recently by the authors,which has also been successfully applied to a wide range of problems in nonlinear sciences.
El Nino Southern Oscillation as Sporadic Oscillations between Metastable States
Institute of Scientific and Technical Information of China (English)
MA Tian; Shouhong WANG
2011-01-01
The main objective of this article is to establish a new mechanism of ENSO, as a self-organizing and selfexcitation system, with two highly coupled processes. The first is the oscillation between the two mctastable warm (El Nino phase) and cold events (La Nina phase), and the second is the spatiotemporal oscillation of the sea surface temperature (SST) field. The symbiotic interplay between these two processes gives rises the climate variability associated with the ENSO, leads to both the random and deterministic features of the ENSO, and defines a new natural feedback mechanism, which drives the sporadic oscillation of the ENSO. The new mechanism is rigorously derived using a dynamic transition theory developed recently by the authors, which has also been successfully applied to a wide range of problems in nonlinear sciences.
Arrays of coupled chemical oscillators
Forrester, Derek Michael
2016-01-01
Oscillating chemical reactions result from complex periodic changes in the concentration of the reactants. In spatially ordered ensembles of candle flame oscillators the fluctuations in the ratio of oxygen atoms with respect to that of carbon, hydrogen and nitrogen produces an oscillation in the visible part of the flame related to the energy released per unit mass of oxygen. Thus, the products of the reaction vary in concentration as a function of time, giving rise to an oscillation in the amount of soot and radiative emission. Synchronisation of interacting dynamical sub-systems occurs as arrays of flames that act as master and slave oscillators, with groups of candles numbering greater than two, creating a synchronised motion in three-dimensions. In a ring of candles the visible parts of each flame move together, up and down and back and forth, in a manner that appears like a "worship". Here this effect is shown for rings of flames which collectively empower a central flame to pulse to greater heights. In ...
Restoration of oscillation in network of oscillators in presence of direct and indirect interactions
Energy Technology Data Exchange (ETDEWEB)
Majhi, Soumen; Bera, Bidesh K. [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India); Bhowmick, Sourav K. [Department of Electronics, Asutosh College, Kolkata-700026 (India); Ghosh, Dibakar, E-mail: diba.ghosh@gmail.com [Physics and Applied Mathematics Unit, Indian Statistical Institute, Kolkata-700108 (India)
2016-10-23
The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau–Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators. - Highlights: • Amplitude death is observed using direct and indirect coupling. • Revival of oscillation using feedback parameter is discussed. • Restoration of oscillation is observed in limit cycle and chaotic systems.
Prediction of pilot induced oscillations
Directory of Open Access Journals (Sweden)
Valentin PANĂ
2011-03-01
Full Text Available An important problem in the design of flight-control systems for aircraft under pilotedcontrol is the determination of handling qualities and pilot-induced oscillations (PIO tendencieswhen significant nonlinearities exist in the vehicle description. The paper presents a method to detectpossible pilot-induced oscillations of Category II (with rate and position limiting, a phenomenonusually due to a misadaptation between the pilot and the aircraft response during some tasks in whichtight closed loop control of the aircraft is required from the pilot. For the analysis of Pilot in the LoopOscillations an approach, based on robust stability analysis of a system subject to uncertainparameters, is proposed. In this analysis the nonlinear elements are substituted by linear uncertainparameters. This approach assumes that PIO are characterized by a limit cycle behavior.
Bloch oscillations in carbon nanotubes
Energy Technology Data Exchange (ETDEWEB)
Jodar, Esther; Perez-Garrido, Antonio [Departamento Fisica Aplicada, Antiguo Hospital de Marina Campus Muralla del Mar, UPCT, Cartagena 30202 Murcia (Spain); Rojas, Fernando [Centro de Nanociencias y Nanotecnologia-UNAM, Apartado Postal 356, Ensenada, Baja California 22800 (Mexico)], E-mail: ejodar@upct.es
2009-05-27
Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case. (fast track communication)
Classical scattering from oscillating targets
Energy Technology Data Exchange (ETDEWEB)
Papachristou, P.K.; Diakonos, F.K.; Constantoudis, V.; Schmelcher, P.; Benet, L
2002-12-30
We study planar classical scattering from an oscillating heavy target whose dynamics defines a five-dimensional phase space. Although the system possesses no periodic orbits, and thus topological chaos is not present, the scattering functions display a variety of structures on different time scales. These structures are due to scattering events with a strong energy transfer from the projectile to the moving disk resulting in low-velocity peaks. We encounter initial conditions for which the projectile exhibits infinitely many bounces with the oscillating disk. Our numerical investigations are supported by analytical results on a specific model with a simple time-law. The observed properties possess universal character for scattering off oscillating targets.
Bloch oscillations in carbon nanotubes.
Jódar, Esther; Pérez-Garrido, Antonio; Rojas, Fernando
2009-05-27
Bloch oscillations arise when electrons are in a one-dimensional linear chain of atoms under a constant electric field. In this paper we show numerically that electrons in different types of carbon nanotubes show oscillations with a Bloch frequency proportional to the constant electric field applied along the nanotube axis. We show these oscillations, calculating the quadratic displacement as a function of the electric field. Because of the double periodicity of the nanotubes' geometry (the lattice constant and the lines of atoms) two frequencies appear, one twice the value of the other. These frequencies coincide perfectly with those predicted for a linear chain of atoms, taking into account the periodicity considered in each case.
Magnetically insulated transmission line oscillator
Energy Technology Data Exchange (ETDEWEB)
Bacon, Larry D. (Albuquerque, NM); Ballard, William P. (Albuquerque, NM); Clark, M. Collins (Albuquerque, NM); Marder, Barry M. (Albuquerque, NM)
1988-01-01
A magnetically insulated transmission line oscillator employs self-generated magnetic fields to generate microwave energy. An anode of the oscillator includes slow-wave structures which are formed of a plurality of thin conductive vanes defining cavities therebetween, and a gap is formed between the anode and a cathode of the oscillator. In response to a pulsed voltage applied to the anode and cathode, self-generated magnetic fields arfe produced in a cross-field orientation with respect to the orientation of the electric field between the anode and the cathode. The cross-field magnetic fields insulate the flow of electrons in the gap and confine the flow of electrons within the gap.
Continuity Controlled Hybrid Automata
Bergstra, J.A.; Middelburg, C.A.
2004-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of
Continuity controlled Hybrid Automata
Bergstra, J.A.; Middelburg, C.A.
2008-01-01
We investigate the connections between the process algebra for hybrid systems of Bergstra and Middelburg and the formalism of hybrid automata of Henzinger et al. We give interpretations of hybrid automata in the process algebra for hybrid systems and compare them with the standard interpretation of
Primordial lepton oscillations and baryogenesis
Energy Technology Data Exchange (ETDEWEB)
Hamada, Yuta [Theory Center, High Energy Accelerator Research Organization (KEK),Tsukuba 305-0801 (Japan); Department of Physics, University of Wisconsin,Madison, WI 53706 (United States); Kitano, Ryuichiro [Theory Center, High Energy Accelerator Research Organization (KEK),Tsukuba 305-0801 (Japan); Department of Particle and Nuclear Physics,The Graduate University for Advanced Studies (Sokendai),Tsukuba 305-0801 (Japan)
2016-11-02
The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the CP violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.
Anomalous Dissipative Quantum Harmonic Oscillator
Institute of Scientific and Technical Information of China (English)
CHEN Dian-Yong; BAI Zhan-Wu; DONG Yu-Bing
2008-01-01
We investigate the low-temperature statistical properties of a harmonic oscillator coupled to a heat bath, where the low-frequency spectrum vanishes. We obtain the exact result of the zero point energy. Due to the low frequency shortage of environmental oscillators' spectral density, the coordinate and momentum correlation functions decay as r-4and r-6 respectively at zero temperature, where T is the correlation time. The low-temperature behavior of the mean energy does not violate the third law of thermodynamics, but differs largely from the Ohmic spectrum case.
Primordial lepton oscillations and baryogenesis
Hamada, Yuta; Kitano, Ryuichiro
2016-11-01
The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the CP violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.
Cherenkov radiation oscillator without reflectors
Li, D.; Wang, Y.; Hangyo, M.; Wei, Y.; Yang, Z.; Miyamoto, S.
2014-05-01
This Letter presents a Cherenkov radiation oscillator with an electron beam travelling over a finitely thick plate made of negative-index materials. In such a scheme, the external reflectors required in the traditional Cherenkov oscillators are not necessary, since the electromagnetic energy flows backward in the negative-index materials, leading to inherent feedback. We theoretically analyzed the interaction between the electron beam and the electromagnetic wave, and worked out the growth rate and start current through numerical calculations. With the help of particle-in-cell simulation, the theoretical predictions are well demonstrated.
Sound oscillation of dropwise cluster
Shavlov, A. V.; Dzhumandzhi, V. A.; Romanyuk, S. N.
2012-06-01
There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60-100 °C. The charge of drops reaches 102-103 units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method.
Smart contact oscillations by IPMCs
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.
Primordial Lepton Oscillations and Baryogenesis
Hamada, Yuta
2016-01-01
The baryon asymmetry of the Universe should have been produced after the inflation era. We consider the possibility that the asymmetry is generated by the flavor oscillations in the reheating process after inflation, so that the baryon asymmetry is realized already at the beginning of the radiation dominated era. In the seesaw model, we show that the propagators of the left-handed leptons generically have flavor mixings in the thermal background, that can generate flavor-dependent lepton asymmetry through the $CP$ violation in the oscillation phenomena. The flavor dependent rates for the wash-out process can leave the net asymmetry today.
Energy Technology Data Exchange (ETDEWEB)
Maccari, A. [Istituto Tecnico `G. Cardano`, Monterotondo, Rome (Italy)
1996-08-01
The most important characteristics of the non-local oscillator, an oscillator subjected to an additional non-local force, are extensively studied by means of a new asymptotic perturbation method that is able to furnish an approximate solution of weakly non-linear differential equations. The resulting motion is doubly periodic, because a second little frequency appears, in addition to the fundamental harmonic frequency. Comparison with the numerical solution obtained by the Runge-Kitta method confirms the validity of the asymptotic perturbation method and its importance for the study of non-linear dynamical systems.
Resonant solar neutrino oscillation versus laboratory neutrino oscillation experiments
Energy Technology Data Exchange (ETDEWEB)
Lim, Chong-Sa
1987-02-01
The interplay between resonant solar neutrino oscillations and neutrino oscillations in laboratory experiments is investigated in a 3 generation model. Due to the assumed hierarchy of neutrino masses, together with our choice of a convenient parameterization of the 3 generation mixing matrix, we can derive a simple analytic formula which reduces the solar neutrino problem to an effective 2 generation problem. The reduction makes it apparent that the allowed range of mixing and mass parameters crucially depend on whether the survival probability of solar neutrinos S satisfies S greater than or equal to 1/3 or not. The formulae for probabilities of laboratory neutrino oscillations are also greatly simplified. We argue that a combination of the observed solar neutrino depletion and data obtained from reactor experiments seems to rule out some range of neutrino masses. If a sizable nu/sub ..mu../ ..-->.. nu/sub e/ oscillation is observed at accelerators, as suggested at this Workshop, it severely restricts the range of 2 mixing angles.
Travelling Waves in Hybrid Chemotaxis Models
Franz, Benjamin
2013-12-18
Hybrid models of chemotaxis combine agent-based models of cells with partial differential equation models of extracellular chemical signals. In this paper, travelling wave properties of hybrid models of bacterial chemotaxis are investigated. Bacteria are modelled using an agent-based (individual-based) approach with internal dynamics describing signal transduction. In addition to the chemotactic behaviour of the bacteria, the individual-based model also includes cell proliferation and death. Cells consume the extracellular nutrient field (chemoattractant), which is modelled using a partial differential equation. Mesoscopic and macroscopic equations representing the behaviour of the hybrid model are derived and the existence of travelling wave solutions for these models is established. It is shown that cell proliferation is necessary for the existence of non-transient (stationary) travelling waves in hybrid models. Additionally, a numerical comparison between the wave speeds of the continuum models and the hybrid models shows good agreement in the case of weak chemotaxis and qualitative agreement for the strong chemotaxis case. In the case of slow cell adaptation, we detect oscillating behaviour of the wave, which cannot be explained by mean-field approximations. © 2013 Society for Mathematical Biology.
Capture into resonance of coupled Duffing oscillators.
Kovaleva, Agnessa
2015-08-01
In this paper we investigate capture into resonance of a pair of coupled Duffing oscillators, one of which is excited by periodic forcing with a slowly varying frequency. Previous studies have shown that, under certain conditions, a single oscillator can be captured into persistent resonance with a permanently growing amplitude of oscillations (autoresonance). This paper demonstrates that the emergence of autoresonance in the forced oscillator may be insufficient to generate oscillations with increasing amplitude in the attachment. A parametric domain, in which both oscillators can be captured into resonance, is determined. The quasisteady states determining the growth of amplitudes are found. An agreement between the theoretical and numerical results is demonstrated.
Green's Function for the Quartic Oscillator
Anderson, Robert L.
2016-01-01
In this paper, a quantum mechanical Green's function $G_{qo}(y_b,t_b;$ $y_a,t_a)$ for the quartic oscillator is presented. This result is built upon two previous papers: first [1], detailing the linearization of the quartic oscillator $(qo)$ to the harmonic oscillator $(ho)$, second [2], the integration of the classical action function for the quartic oscillator. Here an equivalent form for the quartic oscillator action function $S_{qo}(y_b,t_b;$ $y_a,t_a)$ in terms of harmonic oscillator var...
TOWARDS THRESHOLD FREQUENCY IN CHAOTIC COLPITTS OSCILLATOR
DEFF Research Database (Denmark)
Lindberg, Erik; Tamasevicius, Arunas; Mykolaitis, Gytis
2007-01-01
A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations at the funda......A novel version of chaotic Colpitts oscillator is described. Instead of a linear loss resistor, it includes an extra inductor and diode in the collector circuit of the transistor. The modified circuit in comparison with the common Colpitts oscillator may generate chaotic oscillations...
Sound oscillation of dropwise cluster
Energy Technology Data Exchange (ETDEWEB)
Shavlov, A.V., E-mail: shavlov@ikz.ru [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation); Dzhumandzhi, V.A.; Romanyuk, S.N. [Institute of the Earth Cryosphere, RAS Siberian Branch, P.O. 1230, 625000 Tyumen (Russian Federation)
2012-06-04
There was registered sound oscillation of a dropwise cluster formed over the warmed-up water surface. We have calculated the electrical charge of drops on the basis of experimental data on ion-sound oscillation. It was demonstrated that the charge is proportional to surface area of the drops and does not depend on intensity of their evaporation (condensation) in the range of 60–100 °C. The charge of drops reaches 10{sup 2}–10{sup 3} units of elementary charge and coincides on magnitude order with the literary value of a charge calculated by another method. -- Highlights: ► The present investigation registered short-wave sound oscillations of water drops in a dropwise cluster in the range of 60–100 °C. ► We have found autocorrelation functions and Fourier transforms of time series of interdroplet distance; defined oscillation frequencies. ► Calculated electrical charge of drops and specified that the charge is proportional to the drop surface area.
Oscillations in the primordial bispectrum
Meerburg, P.D.
2010-01-01
There exist several models of inflation that produce primordial bispectra that contain a large number of oscillations. In this paper we discuss these models, and aim at finding a method of detecting such bispectra in the data. We explain how the recently proposed method of mode expansion of
Optoelectronic Oscillators for Communication Systems
Romeira, Bruno; Figueiredo, José
We introduce and report recent developments on a novel five port optoelectronic voltage controlled oscillator consisting of a resonant tunneling diode (RTD) optical-waveguide integrated with a laser diode. The RTD-based optoelectronic oscillator (OEO) has both optical and electrical input and output ports, with the fifth port allowing voltage control. The RTD-OEO locks to reference radio-frequency (RF) sources by either optical or electrical injection locking techniques allowing remote synchronization, eliminating the need of impedance matching between traditional RF oscillators. RTD-OEO functions include generation, amplification and distribution of RF carriers, clock recovery, carrier recovery, modulation and demodulation and frequency synthesis. Self-injection locking operation modes, where small portions of the output electrical/optical signals are fed back into the electrical/optical input ports, are also proposed. The self-phase locked loop configuration can give rise to low-noise high-stable oscillations, not limited by the RF source performance and with no need of external optoelectronic conversion.
Cubication of Conservative Nonlinear Oscillators
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…
Testing Localization in Neutrino Oscillations
Zhuridov, Dmitry V.
2012-01-01
The neutrino wave packet localization in short-baseline neutrino oscillation experiments, such as MiniBooNE, is investigated. It is shown that the transition from localization to delocalization may be observed for large neutrino mass splitting of order 1 eV, e.g., in theories with sterile neutrinos.
Mesino oscillation in MFV SUSY
Energy Technology Data Exchange (ETDEWEB)
Berger, Joshua [Cornell University, Department of Physics, LEPP, Ithaca, NY (United States); SLAC National Accelerator Laboratory, Menlo Park, CA (United States); Csaki, Csaba; Grossman, Yuval; Heidenreich, Ben [Cornell University, Department of Physics, LEPP, Ithaca, NY (United States)
2013-04-15
R-parity violating supersymmetry in a Minimal Flavor Violation paradigm can produce same-sign dilepton signals via direct sbottom-LSP pair production. Such signals arise when the sbottom hadronizes and the resulting mesino oscillates into an antimesino. The first bounds on the sbottom mass are placed in this scenario using current LHC results. (orig.)
Observation of anharmonic Bloch oscillations.
Dreisow, Felix; Wang, Gang; Heinrich, Matthias; Keil, Robert; Tünnermann, Andreas; Nolte, Stefan; Szameit, Alexander
2011-10-15
We report on the experimental observation of Bloch oscillations of an optical wave packet in a lattice with second-order coupling. To this end, we employ zigzag waveguide arrays, in which the second-order coupling can be precisely tuned.
Willocq, S
2002-01-01
We review new studies of the time dependence of B0s - B0s-bar mixing by the ALEPH, DELPHI and SLD Collaborations, with an emphasis on the different analysis methods used. Combining all available results yields a preliminary lower limit on the oscillation frequency of dms > 14.4 ps-1 at the 95% C.L.
Solar Magnetic Waves and Oscillations
Erdelyi von Fay-Siebenburgen, R.
2006-11-01
Recent solar and space satellite missions (e.g. SOHO, Trace) and high- resolution ground-based observations (e.g. Swedish Solar Telescope, Dutch Open Telescope) have opened new avenues for 21st century plasma physics. With unprecedented details a very rich and abundant structure of the solar atmosphere is unveiled. Revolutionary observations clearly confirmed the existence of MHD waves and oscillations in a wide range of solar atmospheric magnetic structures, commonly described in the form of solar flux tubes. The objectives of this review are to give an up-to-date account of the theory of MHD waves and oscillations in solar and astrophysical magnetic wave-guides. Since magnetic structuring acts as excellent wave guides, plasma waves and oscillations are able to propagate from sub-surface solar regions through the solar atmosphere deep into the interplanetary space. Observations and theoretical modeling of waves can provide excellent diagnostic tools about the state of solar plasma. Key examples of the various types of MHD waves and oscillations will be discussed both from observational and theoretical perspectives and the concept of atmospheric (coronal) and magneto-seismology will be introduced. The lecture will also contain a few short exercises in order to highlight the important points of the applications of solar MHD wave theory.
Tunable Oscillations in the Purkinje Neuron
Abrams, Ze'ev R; Wang, Yuan; Trauner, Dirk; Zhang, Xiang
2011-01-01
In this paper, we study the dynamics of slow oscillations in Purkinje neurons in vitro, and derive a strong association with a forced parametric oscillator model. We demonstrate the precise rhythmicity of the oscillations in Purkinje neurons, as well as a dynamic tunability of this oscillation using a photo-switchable compound. We show that this slow oscillation can be induced in every Purkinje neuron, having periods ranging between 10-25 seconds. Starting from a Hodgkin-Huxley model, we also demonstrate that this oscillation can be externally modulated, and that the neurons will return to their intrinsic firing frequency after the forced oscillation is concluded. These results signify an additional functional role of tunable oscillations within the cerebellum, as well as a dynamic control of a time scale in the brain in the range of seconds.
Opto-Electronic Oscillator and its Applications
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.
Institute of Scientific and Technical Information of China (English)
赵茜; 瞿文慧; 姜建国
2016-01-01
The subsynchronous oscillation situation of Hulun Buir League power system is complicated for there are se -ries capacitor compensation lines as well as DC transmission lines .A comprehensive introduction to Subsynchronous oscillation and mitigation situation of power plants in Hulun Buir League power system is given in this paper .The sus-tained low amplitude Subsynchronous oscillation phenomenon in Ewenki Power Plant is emphasized .Aiming at this phenomenon , a simplified model of Hulun Buir League power system is proposed and the time -domain simulation based on MATLAB is carry out .Simulation results match with the practical situation on site , which verified the cor-rectness of the model .This research of subsynchronous oscillation lays a foundation for further study of subsequent mitigation measures in Ewenki power plant .%呼盟煤电基地电力系统中既包含交流串联补偿线路,又包含直流输电线路,次同步振荡情况复杂.文中对呼盟系统中各电厂的次同步振荡及抑制情况进行了全面的介绍,指出鄂温克电厂"持续存在的小幅次同步振荡"这一新情况.针对这一情况,对呼盟复杂互联系统进行化简建模,在MATLAB仿真平台上进行时域仿真.仿真结果与实际现场运行状况相符.仿真波形与实际录波波形的比较也验证了模型的正确性.对鄂温克电厂次同步振荡特性的分析为后续抑制措施的研究奠定了基础.
Nonlinear analysis of ring oscillator circuits
Ge, Xiaoqing
2010-06-01
Using nonlinear systems techniques, we analyze the stability properties and synchronization conditions for ring oscillator circuits, which are essential building blocks in digital systems. By making use of its cyclic structure, we investigate local and global stability properties of an n-stage ring oscillator. We present a sufficient condition for global asymptotic stability of the origin and obtain necessity if the ring oscillator consists of identical inverter elements. We then give a synchronization condition for identical interconnected ring oscillators.
Internal dynamics of long Josephson junction oscillators
DEFF Research Database (Denmark)
Christiansen, Peter Leth; Lomdahl, P. S.; Scott, Alwyn C.;
1981-01-01
Numerical computations on a sine-Gordon model of the Josephson junction fluxon oscillator are compared with experimental measurements. Good agreement is found for the voltage current characteristic, oscillator power output, and range of current bias over which oscillation is observed. Our numeric...... results imply a ''bunched-fluxon'' mode of oscillation at larger values of bias current. Applied Physics Letters is copyrighted by The American Institute of Physics....
Optical analogue of electronic Bloch oscillations.
Sapienza, Riccardo; Costantino, Paola; Wiersma, Diederik; Ghulinyan, Mher; Oton, Claudio J; Pavesi, Lorenzo
2003-12-31
We report on the observation of Bloch oscillations in light transport through periodic dielectric systems. By introducing a linear refractive index gradient along the propagation direction the optical equivalent of a Wannier-Stark ladder was obtained. Bloch oscillations were observed as time-resolved oscillations in transmission, in direct analogy to electronic Bloch oscillations in conducting crystals where the Wannier-Stark ladder is obtained via an external electric field. The observed oscillatory behavior is in excellent agreement with transfer matrix calculations.
Comparison of Methods for Oscillation Detection
DEFF Research Database (Denmark)
Odgaard, Peter Fogh; Trangbæk, Klaus
2006-01-01
This paper compares a selection of methods for detecting oscillations in control loops. The methods are tested on measurement data from a coal-fired power plant, where some oscillations are occurring. Emphasis is put on being able to detect oscillations without having a system model and without...... using process knowledge. The tested methods show potential for detecting the oscillations, however, transient components in the signals cause false detections as well, motivating usage of models in order to remove the expected signals behavior....
Parametric resonance in neutrino oscillations in matter
Indian Academy of Sciences (India)
E Kh Akhmedov
2000-01-01
Neutrino oscillations in matter can exhibit a specific resonance enhancement - parametric resonance, which is different from the MSW resonance. Oscillations of atmospheric and solar neutrinos inside the earth can undergo parametric enhancement when neutrino trajectories cross the core of the earth. In this paper we review the parametric resonance of neutrino oscillations in matter. In particular, physical interpretation of the effect and the prospects of its experimental observation in oscillations of solar and atmospheric neutrinos in the earth are discussed.
Scleronomic Holonomic Constraints and Conservative Nonlinear Oscillators
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…
Control linearity and jitter of relaxation oscillators
Gierkink, Sander Laurentius Johannes
1999-01-01
The body of this thesis (chapters 3,4 and 5) deals with the analysis and improvement of a specific class of voltage- or current controlled oscillators (VCO’s respectively CCO’s) called relaxation oscillators. Before going into detail on this particular class of oscillators, first the function and ap
The SD oscillator and its attractors
Energy Technology Data Exchange (ETDEWEB)
Cao, Q [Department of Mathematics and Physics, Shijiazhuang Railway Institute, Shijiazhuang 050043 (China); Wiercigroch, M; Pavlovskaia, E; Grebogi, C; Michael, J; Thompson, T [Centre for Applied Dynamics Research, School of Engineering, University of Aberdeen, King' s College, Aberdeen AB24 3UE, Scotland (United Kingdom)], E-mail: qingjiecao@hotmail.com
2008-02-15
We propose a new archetypal oscillator for smooth and discontinuous systems (SD oscillator). This oscillator behaves both smooth and discontinuous system depending on the value of the smoothness parameter. New dynamic behaviour is presented for the transitions from the smooth to discontinuous regime.
Bloch-Zener oscillations in binary superlattices.
Dreisow, F; Szameit, A; Heinrich, M; Pertsch, T; Nolte, S; Tünnermann, A; Longhi, S
2009-02-20
Bloch-Zener oscillations, i.e., the coherent superposition of Bloch oscillations and Zener tunneling between minibands of a binary lattice, are experimentally demonstrated for light waves in curved femtosecond laser-written waveguide arrays. Visualization of double-periodicity breathing and oscillation modes is reported, and synchronous tunneling leading to wave reconstruction is demonstrated.
Harmonic oscillator: an analysis via Fourier series
de Castro, A S
2013-01-01
The Fourier series method is used to solve the homogeneous equation governing the motion of the harmonic oscillator. It is shown that the general solution to the problem can be found in a surprisingly simple way for the case of the simple harmonic oscillator. It is also shown that the damped harmonic oscillator is susceptible to the analysis.
On the excitation of Goodwin's oscillations
Antonova, A. O.; Reznik, S. N.; Todorov, M. D.
2014-11-01
We consider the necessary condition for excitation of long-periodic Goodwin's oscillations and short-periodic sawtooth oscillations in the Goodwin model with fixed delay in the induced investment. Also, using the method of equivalent linearization we evaluate the amplitude of steady-state oscillation.
On the mechanism of oscillations in neutrophils
DEFF Research Database (Denmark)
Brasen, Jens Christian; Barington, Torben; Olsen, Lars Folke
2010-01-01
We have investigated the regulation of the oscillatory generation of H(2)O(2) and oscillations in shape and size in neutrophils in suspension. The oscillations are independent of cell density and hence do not represent a collective phenomena. Furthermore, the oscillations are independent of the e...
Observation of a Hybrid Spin Resonance
Bai, M.; Allgower, C.; Ahrens, L.; Alessi, J.; Brown, K.; Bunce, G.; Cameron, P.; Chu, C. M.; Courant, E. D.; Glenn, J. W.; Huang, H.; Jeon, D.; Kponou, A. E.; Krueger, K.; Luccio, A.; Makdisi, Y. I.; Lee, S. Y.; Ratner, L.; Reece, K.; Roser, T.; Spinka, H.; Syphers, M. J.; Tsoupas, N.; Underwood, D. G.; van Asselt, W.; Williams, N.; Yokosawa, A.
2000-02-01
A new type of spin depolarization resonance has been observed at the Brookhaven Alternating Gradient Synchrotron (AGS). This spin resonance is identified as a strong closed-orbit sideband around the dominant intrinsic spin resonance. The strength of the resonance was proportional to the 9th harmonic component of the horizontal closed orbit and proportional to the vertical betatron oscillation amplitude. This ``hybrid'' spin resonance cannot be overcome by the partial snake at the AGS, but it can be corrected by the harmonic orbit correctors.
Time domain oscillating poles: Stability redefined in Memristor based Wien-oscillators
Talukdar, Abdul Hafiz Ibne
2012-07-28
Traditionally, the necessary and sufficient condition for any system to be oscillating is that its poles are located on the imaginary (jω) axis. In this paper, for the first time, we have shown that systems can oscillate with time-domain oscillating poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating resistance and triangular shape of FFT are also demonstrated with mathematical reasoning and simulation results to support the unusual and surprising characteristics. © 2009 IEEE.
The effect of phase stabilization of microwave oscillations in nanosecond Gunn oscillators
Konev, V. Yu.; Klimov, A. I.; Koval'chuk, O. B.; Gubanov, V. P.; Kozhevnikov, V. Yu.; Kozyrev, A. V.; Torkhov, N. A.
2013-11-01
The effect of the semiconductor structure of an oscillator diode on the phase stabilization of microwave oscillations in a nanosecond Gunn oscillator by using a modulating voltage pulse edge is investigated. Numerical simulation is employed to determine phase deviations depending on the scatter of pulseedge duration and pulse amplitude. The standard deviation of phase-delay time of microwave oscillations in the oscillator with regard to a constant level at the modulating pulse edge and the standard deviation of phase difference of microwave oscillations in two electrodynamically insulated oscillators connected in parallel to one and the same modulator have been measured.
Restoration of oscillation in network of oscillators in presence of direct and indirect interactions
Majhi, Soumen; Bera, Bidesh K.; Bhowmick, Sourav K.; Ghosh, Dibakar
2016-10-01
The suppression of oscillations in coupled systems may lead to several unwanted situations, which requires a suitable treatment to overcome the suppression. In this paper, we show that the environmental coupling in the presence of direct interaction, which can suppress oscillation even in a network of identical oscillators, can be modified by introducing a feedback factor in the coupling scheme in order to restore the oscillation. We inspect how the introduction of the feedback factor helps to resurrect oscillation from various kinds of death states. We numerically verify the resurrection of oscillations for two paradigmatic limit cycle systems, namely Landau-Stuart and Van der Pol oscillators and also in generic chaotic Lorenz oscillator. We also study the effect of parameter mismatch in the process of restoring oscillation for coupled oscillators.
Measuring neutrino oscillation parameters using $\
Energy Technology Data Exchange (ETDEWEB)
Backhouse, Christopher James [Oriel College, Oxford (United Kingdom)
2011-01-01
MINOS is a long-baseline neutrino oscillation experiment. It consists of two large steel-scintillator tracking calorimeters. The near detector is situated at Fermilab, close to the production point of the NuMI muon-neutrino beam. The far detector is 735 km away, 716m underground in the Soudan mine, Northern Minnesota. The primary purpose of the MINOS experiment is to make precise measurements of the 'atmospheric' neutrino oscillation parameters (Δm_{atm}^{2} and sin^{2} 2θ_{atm}). The oscillation signal consists of an energy-dependent deficit of v_{μ} interactions in the far detector. The near detector is used to characterize the properties of the beam before oscillations develop. The two-detector design allows many potential sources of systematic error in the far detector to be mitigated by the near detector observations. This thesis describes the details of the v_{μ}-disappearance analysis, and presents a new technique to estimate the hadronic energy of neutrino interactions. This estimator achieves a significant improvement in the energy resolution of the neutrino spectrum, and in the sensitivity of the neutrino oscillation fit. The systematic uncertainty on the hadronic energy scale was re-evaluated and found to be comparable to that of the energy estimator previously in use. The best-fit oscillation parameters of the v_{μ}-disappearance analysis, incorporating this new estimator were: Δm^{2} = 2.32_{-0.08}^{+0.12} x 10^{-3} eV^{2}, sin ^{2} 2θ > 0.90 (90% C.L.). A similar analysis, using data from a period of running where the NuMI beam was operated in a configuration producing a predominantly $\\bar{v}$_{μ} beam, yielded somewhat different best-fit parameters Δ$\\bar{m}${sup 2} = (3.36_{-0.40}^{+0.46}(stat.) ± 0.06(syst.)) x 10^{-3}eV^{2}, sin^{2} 2$\\bar{θ}$ = 0.86_{-0.12}^{_0}
Photonic cavity synchronization of nanomechanical oscillators.
Bagheri, Mahmood; Poot, Menno; Fan, Linran; Marquardt, Florian; Tang, Hong X
2013-11-22
Synchronization in oscillatory systems is a frequent natural phenomenon and is becoming an important concept in modern physics. Nanomechanical resonators are ideal systems for studying synchronization due to their controllable oscillation properties and engineerable nonlinearities. Here we demonstrate synchronization of two nanomechanical oscillators via a photonic resonator, enabling optomechanical synchronization between mechanically isolated nanomechanical resonators. Optical backaction gives rise to both reactive and dissipative coupling of the mechanical resonators, leading to coherent oscillation and mutual locking of resonators with dynamics beyond the widely accepted phase oscillator (Kuramoto) model. In addition to the phase difference between the oscillators, also their amplitudes are coupled, resulting in the emergence of sidebands around the synchronized carrier signal.
Memristor-based reactance-less oscillator
Zidan, Mohammed A.
2012-10-02
The first reactance-less oscillator is introduced. By using a memristor, the oscillator can be fully implemented on-chip without the need for any capacitors or inductors, which results in an area-efficient fully integrated solution. The concept of operation of the proposed oscillator is explained and detailed mathematical analysis is introduced. Closed-form expressions for the oscillation frequency and oscillation conditions are derived. Finally, the derived equations are verified with circuit simulations showing excellent agreement. © 2011 The Institution of Engineering and Technology.
From hybrid swarms to swarms of hybrids
The introgression of modern humans (Homo sapiens) with Neanderthals 40,000 YBP after a half-million years of separation, may have led to the best example of a hybrid swarm on earth. Modern trade and transportation in support of the human hybrids has continued to introduce additional species, genotyp...
The Hybrid Museum: Hybrid Economies of Meaning
DEFF Research Database (Denmark)
Vestergaard, Vitus
2013-01-01
this article shows that there are two different museum mindsets where the second mindset leans towards participatory practices. It is shown how a museum can support a hybrid economy of meaning that builds on both a user generated economy of meaning and an institutional economy of meaning and adds value to both....... Such a museum is referred to as a hybrid museum....
EPA and the United Parcel Service (UPS) have developed a hydraulic hybrid delivery vehicle to explore and demonstrate the environmental benefits of the hydraulic hybrid for urban pick-up and delivery fleets.
Hybrid Management in Hospitals
DEFF Research Database (Denmark)
Byrkjeflot, Haldor; Jespersen, Peter Kragh
2010-01-01
Artiklen indeholder et litteraturbaseret studium af ledelsesformer i sygehuse, hvor sundhedsfaglig ledelse og generel ledelse mikses til hybride ledelsesformer......Artiklen indeholder et litteraturbaseret studium af ledelsesformer i sygehuse, hvor sundhedsfaglig ledelse og generel ledelse mikses til hybride ledelsesformer...
Electromechanical oscillations in bilayer graphene
Benameur, Muhammed M.; Gargiulo, Fernando; Manzeli, Sajedeh; Autès, Gabriel; Tosun, Mahmut; Yazyev, Oleg V.; Kis, Andras
2015-10-01
Nanoelectromechanical systems constitute a class of devices lying at the interface between fundamental research and technological applications. Realizing nanoelectromechanical devices based on novel materials such as graphene allows studying their mechanical and electromechanical characteristics at the nanoscale and addressing fundamental questions such as electron-phonon interaction and bandgap engineering. In this work, we realize electromechanical devices using single and bilayer graphene and probe the interplay between their mechanical and electrical properties. We show that the deflection of monolayer graphene nanoribbons results in a linear increase in their electrical resistance. Surprisingly, we observe oscillations in the electromechanical response of bilayer graphene. The proposed theoretical model suggests that these oscillations arise from quantum mechanical interference in the transition region induced by sliding of individual graphene layers with respect to each other. Our work shows that bilayer graphene conceals unexpectedly rich and novel physics with promising potential in applications based on nanoelectromechanical systems.
Electronically Tunable Sinusoidal Oscillator Circuit
Directory of Open Access Journals (Sweden)
Sudhanshu Maheshwari
2012-01-01
Full Text Available This paper presents a novel electronically tunable third-order sinusoidal oscillator synthesized from a simple topology, employing current-mode blocks. The circuit is realized using the active element: Current Controlled Conveyors (CCCIIs and grounded passive components. The new circuit enjoys the advantages of noninteractive electronically tunable frequency of oscillation, use of grounded passive components, and the simultaneous availability of three sinusoidal voltage outputs. Bias current generation scheme is given for the active elements used. The circuit exhibits good high frequency performance. Nonideal and parasitic study has also been carried out. Wide range frequency tuning is shown with the bias current. The proposed theory is verified through extensive PSPICE simulations using 0.25 μm CMOS process parameters.
Status of sterile neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Schwetz, Thomas
2013-02-15
There are several independent hints for neutrino oscillations with a mass-squared difference at the eV{sup 2} scale. If confirmed, this would imply the existence of sterile neutrinos. I discuss the present status of the hints for ν{sub e} disappearance from reactor experiments and Gallium source experiments, as well as from the LSND and MiniBooNE ν{sub μ}→ν{sub e} appearance searches. A consistent interpretation of the global data in terms of neutrino oscillations is challenged by the non-observation of a positive signal in ν{sub μ} disappearance experiments. There is a strong tension in the global data, irrespective of the number of eV-scale neutrino states.
Oscillators: Old and new perspectives
Energy Technology Data Exchange (ETDEWEB)
Bhattacharjee, Jayanta K. [Harish-Chandra Research Institute, Jhunsi, Allahabad 211019 (India); Roy, Jyotirmoy [UM-DAE Centre for Excellence in Basic Sciences, Santa Cruz(E), Mumbai 400098 (India)
2014-02-11
We consider some of the well known oscillators in literature which are known to exhibit interesting effects of nonlinearity. We review the Lindstedt-Poincare technique for dealing with with the nonlinear effects and then go on to introduce the relevance of the renormalization group for the oscillator following the pioneering work of Chen et al. It is pointed out that the traditional Lindstedt-Poincare and the renormalization group techniques have operational connections. We use this to find an unexpected mode softening in the double pendulum. This mode softening prompted us to look for chaos in the double pendulum at low energies-energies that are just sufficient to allow the outer pendulum to rotate (the double pendulum is known to be chaotic at high energies-energies that are greater than that needed to make both pendulums to rotate). The emergence of the chaos is strongly dependent on initial conditions.
A Tunable Carbon Nanotube Oscillator
Sazonova, Vera
2005-03-01
Nanoelectromechanical systems (NEMS) hold promise for a number of scientific and technological applications. Carbon nanotubes (NT) are perhaps the ultimate material for realizing a NEMS device as they are the stiffest material known, have low density, ultrasmall cross sections and can be defect-free. Equally important, a nanotube can act as a transistor and thus is able to sense its own motion. Here, we report the electrical actuation and detection of the guitar-string oscillation modes of doubly-clamped NT oscillators. We observed resonance frequencies in the 5MHz to 150MHz range with quality factors in the 50 to 100 range. We showed that the resonance frequencies can be widely tuned by a gate voltage. We also report on the temperature dependence of the quality factor and present a discussion of possible loss mechanisms.
Neutrino Oscillations in Dense Matter
Lobanov, A. E.
2017-03-01
A modification of the electroweak theory, where the fermions with the same electroweak quantum numbers are combined in multiplets and are treated as different quantum states of a single particle, is proposed. In this model, mixing and oscillations of particles arise as a direct consequence of the general principles of quantum field theory. The developed approach enables one to calculate the probabilities of the processes taking place in the detector at long distances from the particle source. Calculations of higher-order processes, including computation of the contributions due to radiative corrections, can be performed in the framework of the perturbation theory using the regular diagram technique. As a result, the analog to the Dirac-Schwinger equation of quantum electrodynamics describing neutrino oscillations and its spin rotation in dense matter can be obtained.
Electrochemical Oscillations Induced by Surfactants
Institute of Scientific and Technical Information of China (English)
翟俊红; 贺占博
2003-01-01
A new type of electrochemical oscillation induced by surfactant was observed in experiments. The electrochemical system is a Daniell cell with a copper rod in CuSO4 aqueous and an aluminum rod in Al(NO3)3 aqueous as electrodes. The surfactants are CTAB, TX-100, SLS. The addition of trace surfactant solution by a micro-syringe made the original monotonously changing electrochemical system produce obvious periodic phenomena. At the mean time, the copper ion selective electrode and Hg2SO4 reference electrode were used to monitor the copper electrode reaction and determine its rate constant k of first order reaction. According to the experimental results of electrode reaction kinetics, the possible mechanism was found to be the polarization induced from the directional adsorption of trace surfactant on the electrode surface. That is the electrochemical oscillations.
Experimental studies of neutrino oscillations
Kajita, Takaaki
2016-01-01
The 2015 Nobel Prize in physics has been awarded to Takaaki Kajita and Arthur McDonald "for the discovery of neutrino oscillations, which shows that neutrinos have mass". Takaaki Kajita of Tokyo University is a Japanese physicist, known for neutrino experiments at the Kamiokande and its successor, Super-Kamiokande. This volume of collected works of Kajita on neutrino oscillations provides a good glimpse into as well as a record of the rise and the role of Asian research in the frontiers of neutrino physics. Japan is now a major force in the study of the 3 families of neutrinos. Much remains to be done to clarify the Dirac vs. Majorana nature of the neutrino, and the cosmological implications of the neutrino. The collected works of Kajita and his Super-Kamiokande group will leave an indelible foot-print in the history of big and better science.
Cubication of conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Belendez, Augusto; Alvarez, Mariela L [Departamento de Fisica, Ingenieria de Sistemas y Teoria de la Senal, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain); Fernandez, Elena; Pascual, Inmaculada [Departamento de Optica, FarmacologIa y Anatomia, Universidad de Alicante, Apartado 99, E-03080 Alicante (Spain)], E-mail: a.belendez@ua.es
2009-09-15
A cubication procedure of the nonlinear differential equation for conservative nonlinear oscillators is analysed and discussed. This scheme is based on the Chebyshev series expansion of the restoring force, and this allows us to approximate the original nonlinear differential equation by a Duffing equation in which the coefficients for the linear and cubic terms depend on the initial amplitude, A, while in a Taylor expansion of the restoring force these coefficients are independent of A. The replacement of the original nonlinear equation by an approximate Duffing equation allows us to obtain an approximate frequency-amplitude relation as a function of the complete elliptic integral of the first kind. Some conservative nonlinear oscillators are analysed to illustrate the usefulness and effectiveness of this scheme.
Directory of Open Access Journals (Sweden)
Yosef London
2017-04-01
Full Text Available An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified, and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics.
London, Yosef; Diamandi, Hilel Hagai; Zadok, Avi
2017-04-01
An opto-electronic radio-frequency oscillator that is based on forward scattering by the guided acoustic modes of a standard single-mode optical fiber is proposed and demonstrated. An optical pump wave is used to stimulate narrowband, resonant guided acoustic modes, which introduce phase modulation to a co-propagating optical probe wave. The phase modulation is converted to an intensity signal at the output of a Sagnac interferometer loop. The intensity waveform is detected, amplified, and driven back to modulate the optical pump. Oscillations are achieved at a frequency of 319 MHz, which matches the resonance of the acoustic mode that provides the largest phase modulation of the probe wave. Oscillations at the frequencies of competing acoustic modes are suppressed by at least 40 dB. The linewidth of the acoustic resonance is sufficiently narrow to provide oscillations at a single longitudinal mode of the hybrid cavity. Competing longitudinal modes are suppressed by at least 38 dB as well. Unlike other opto-electronic oscillators, no radio-frequency filtering is required within the hybrid cavity. The frequency of oscillations is entirely determined by the fiber opto-mechanics.
Multipartite entanglement in neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Blasone, Massimo; Dell' Anno, Fabio; De Siena, Silvio; Illuminati, Fabrizio, E-mail: blasone@sa.infn.i [Dipartimento di Matematica e Informatica, Universita degli Studi di Salerno, Via Ponte don Melillo, I-84084 Fisciano (Italy)
2009-06-01
Particle mixing is related to multi-mode entanglement of single-particle states The occupation number of both flavor eigenstates and mass eigenstates can be used to define a multiqubit space. In such a framework, flavor neutrino states can be interpreted as multipartite mode-entangled states. By using two different entanglement measures, we analyze the behavior of multipartite entanglement in the phenomenon of neutrino oscillations.
Mathematical Models of Biochemical Oscillations
Conrad, Emery David
1999-01-01
The goal of this paper is to explain the mathematics involved in modeling biochemical oscillations. We first discuss several important biochemical concepts fundamental to the construction of descriptive mathematical models. We review the basic theory of differential equations and stability analysis as it relates to two-variable models exhibiting oscillatory behavior. The importance of the Hopf Bifurcation will be discussed in detail for the central role it plays in limit cycle behavior and...
Ermakov approach for minisuperspace oscillators
Rosu, H. C.; Socorro, J.
1999-01-01
The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a p...
Neutrino Masses and Flavor Oscillations
Wang, Yifang; Xing, Zhi-Zhong
2016-10-01
This essay is intended to provide a brief description of the peculiar properties of neutrinos within and beyond the standard theory of weak interactions. The focus is on the flavor oscillations of massive neutrinos, from which one has achieved some striking knowledge about their mass spectrum and flavor mixing pattern. The experimental prospects towards probing the absolute neutrino mass scale, possible Majorana nature and CP-violating effects, will also be addressed.
Institute of Scientific and Technical Information of China (English)
S. Asaoka
2005-01-01
@@ 1Introduction: What are resin catalyst hybrids? There are typically two types of resin catalyst. One is acidic resin which representative is polystyrene sulfonic acid. The other is basic resin which is availed as metal complex support. The objective items of this study on resin catalyst are consisting of pellet hybrid, equilibrium hybrid and function hybrid of acid and base,as shown in Fig. 1[1-5].
Mesoscale hybrid calibration artifact
Tran, Hy D.; Claudet, Andre A.; Oliver, Andrew D.
2010-09-07
A mesoscale calibration artifact, also called a hybrid artifact, suitable for hybrid dimensional measurement and the method for make the artifact. The hybrid artifact has structural characteristics that make it suitable for dimensional measurement in both vision-based systems and touch-probe-based systems. The hybrid artifact employs the intersection of bulk-micromachined planes to fabricate edges that are sharp to the nanometer level and intersecting planes with crystal-lattice-defined angles.
Amplification of kinetic oscillations in gene expression
Zhdanov, V. P.
2008-10-01
Because of the feedbacks between the DNA transcription and mRNA translation, the gene expression in cells may exhibit bistability and oscillations. The deterministic and stochastic calculations presented illustrate how the bistable kinetics of expression of one gene in a cell can be influenced by the kinetic oscillations in the expression of another gene. Due to stability of the states of the bistable kinetics of gene 1 and the relatively small difference between the maximum and minimum protein amounts during the oscillations of gene 2, the induced oscillations of gene 1 are found to typically be related either to the low-or high-reactive state of this gene. The quality of the induced oscillations may be appreciably better than that of the inducing oscillations. This means that gene 1 can serve as an amplifier of the kinetic oscillations of gene 2.
Quantum dynamics of the damped harmonic oscillator
Philbin, T G
2012-01-01
The quantum theory of the damped harmonic oscillator has been a subject of continual investigation since the 1930s. The obstacle to quantization created by the dissipation of energy is usually dealt with by including a discrete set of additional harmonic oscillators as a reservoir. But a discrete reservoir cannot directly yield dynamics such as Ohmic damping (proportional to velocity) of the oscillator of interest. By using a continuum of oscillators as a reservoir, we canonically quantize the harmonic oscillator with Ohmic damping and also with general damping behaviour. The dynamics of a damped oscillator is determined by an arbitrary effective susceptibility that obeys Kramers-Kronig relations. This approach offers an alternative description of nano-mechanical oscillators and opto-mechanical systems.
Neutrino Oscillation Experiment at JHF
2002-01-01
T2K is a long baseline neutrino experiment designed to investigate how neutrinos change from one flavor to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K, 295 km away: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos. The high intensity neutrino beam is produced in an off-axis configuration. The peak neutrino energy is tuned to the oscillation maximum of ∼ 0.6 GeV to maximize the sensitivity to neutrino oscillations. The science goals of T2K can be summarized as follows: •\tsearch for CP violation in the neutrino sector •\tdiscovery of νμ → νe ( i.e. the confirmation that θ13 > 0 ) •\tprecision ...
Micro-machined resonator oscillator
Koehler, Dale R.; Sniegowski, Jeffry J.; Bivens, Hugh M.; Wessendorf, Kurt O.
1994-01-01
A micro-miniature resonator-oscillator is disclosed. Due to the miniaturization of the resonator-oscillator, oscillation frequencies of one MHz and higher are utilized. A thickness-mode quartz resonator housed in a micro-machined silicon package and operated as a "telemetered sensor beacon" that is, a digital, self-powered, remote, parameter measuring-transmitter in the FM-band. The resonator design uses trapped energy principles and temperature dependence methodology through crystal orientation control, with operation in the 20-100 MHz range. High volume batch-processing manufacturing is utilized, with package and resonator assembly at the wafer level. Unique design features include squeeze-film damping for robust vibration and shock performance, capacitive coupling through micro-machined diaphragms allowing resonator excitation at the package exterior, circuit integration and extremely small (0.1 in. square) dimensioning. A family of micro-miniature sensor beacons is also disclosed with widespread applications as bio-medical sensors, vehicle status monitors and high-volume animal identification and health sensors. The sensor family allows measurement of temperatures, chemicals, acceleration and pressure. A microphone and clock realization is also available.
Automatic oscillator frequency control system
Smith, S. F. (Inventor)
1985-01-01
A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.
Pinfield, Stephen; Eaton, Jonathan; Edwards, Catherine; Russell, Rosemary; Wissenburg, Astrid; Wynne, Peter
1998-01-01
Outlines five projects currently funded by the United Kingdom's Electronic Libraries Program (eLib): HyLiFe (Hybrid Library of the Future), MALIBU (MAnaging the hybrid Library for the Benefit of Users), HeadLine (Hybrid Electronic Access and Delivery in the Library Networked Environment), ATHENS (authentication scheme), and BUILDER (Birmingham…
Homoploid hybrid speciation occurs when a stable, fertile, and reproductively isolated lineage results from hybridization between two distinct species without a change in ploidy level. Reproductive isolation between a homoploid hybrid species and its parents is generally attained via chromosomal re...
Hawke, Ronald S.; Asay, James R.; Hall, Clint A.; Konrad, Carl H.; Sauve, Gerald L.; Shahinpoor, Mohsen; Susoeff, Allan R.
1993-01-01
A projectile for a railgun that uses a hybrid armature and provides a seed block around part of the outer surface of the projectile to seed the hybrid plasma brush. In addition, the hybrid armature is continuously vaporized to replenish plasma in a plasma armature to provide a tandem armature and provides a unique ridge and groove to reduce plasama blowby.
Intraply Hybrid Composite Design
Chamis, C. C.; Sinclair, J. H.
1986-01-01
Several theoretical approaches combined in program. Intraply hybrid composites investigated theoretically and experimentally at Lewis Research Center. Theories developed during investigations and corroborated by attendant experiments used to develop computer program identified as INHYD (Intraply Hybrid Composite Design). INHYD includes several composites micromechanics theories, intraply hybrid composite theories, and integrated hygrothermomechanical theory. Equations from theories used by program as appropriate for user's specific applications.
Hybrid quantum information processing
Energy Technology Data Exchange (ETDEWEB)
Furusawa, Akira [Department of Applied Physics, School of Engineering, The University of Tokyo (Japan)
2014-12-04
I will briefly explain the definition and advantage of hybrid quantum information processing, which is hybridization of qubit and continuous-variable technologies. The final goal would be realization of universal gate sets both for qubit and continuous-variable quantum information processing with the hybrid technologies. For that purpose, qubit teleportation with a continuousvariable teleporter is one of the most important ingredients.
Directory of Open Access Journals (Sweden)
Mohd Rashid Muhammad Ikram
2017-01-01
Full Text Available Electric vehicle suffers from relatively short range and long charging times and consequently has not become an acceptable solution to the automotive consumer. The addition of an internal combustion engine to extend the range of the electric vehicle is one method of exploiting the high efficiency and lack of emissions of the electric vehicle while retaining the range and convenient refuelling times of a conventional gasoline powered vehicle. The term that describes this type of vehicle is a hybrid electric vehicle. Many configurations of hybrid electric vehicles have been designed and implemented, namely the series, parallel and power-split configurations. This paper discusses the comparison between Split Plug-in Hybrid Electric Vehicle(SPHEV and Hybrid Electric Vehicle(HEV. Modelling methods such as physics-based Resistive Companion Form technique and Bond Graph method are presented with powertrain component and system modelling examples. The modelling and simulation capability of existing tools such as ADvanced VehIcle SimulatOR (ADVISOR is demonstrated through application examples. Since power electronics is indispensable in hybrid vehicles, the issue of numerical oscillations in dynamic simulations involving power electronics is briefly addressed.
Dysrhythmias of the respiratory oscillator
Paydarfar, David; Buerkel, Daniel M.
1995-03-01
Breathing is regulated by a central neural oscillator that produces rhythmic output to the respiratory muscles. Pathological disturbances in rhythm (dysrhythmias) are observed in the breathing pattern of children and adults with neurological and cardiopulmonary diseases. The mechanisms responsible for genesis of respiratory dysrhythmias are poorly understood. The present studies take a novel approach to this problem. The basic postulate is that the rhythm of the respiratory oscillator can be altered by a variety of stimuli. When the oscillator recovers its rhythm after such perturbations, its phase may be reset relative to the original rhythm. The amount of phase resetting is dependent upon stimulus parameters and the level of respiratory drive. The long-range hypothesis is that respiratory dysrhythmias can be induced by stimuli that impinge upon or arise within the respiratory oscillator with certain combinations of strength and timing relative to the respiratory cycle. Animal studies were performed in anesthetized or decerebrate preparations. Neural respiratory rhythmicity is represented by phrenic nerve activity, allowing use of open-loop experimental conditions which avoid negative chemical feedback associated with changes in ventilation. In animal experiments, respiratory dysrhythmias can be induced by stimuli having specific combinations of strength and timing. Newborn animals readily exhibit spontaneous dysrhythmias which become more prominent at lower respiratory drives. In human subjects, swallowing was studied as a physiological perturbation of respiratory rhythm, causing a pattern of phase resetting that is characterized topologically as type 0. Computational studies of the Bonhoeffer-van der Pol (BvP) equations, whose qualitative behavior is representative of many excitable systems, supports a unified interpretation of these experimental findings. Rhythmicity is observed when the BvP model exhibits recurrent periods of excitation alternating with
Energy Technology Data Exchange (ETDEWEB)
Smith, J.R.
1993-10-15
The energy efficiency of various piston engine options for series hybrid automobiles are compared with conventional, battery powered electric, and proton exchange membrane (PEM) fuel cell hybrid automobiles. Gasoline, compressed natural gas (CNG), and hydrogen are considered for these hybrids. The engine and fuel comparisons are done on a basis of equal vehicle weight, drag, and rolling resistance. The relative emissions of these various fueled vehicle options are also presented. It is concluded that a highly optimized, hydrogen fueled, piston engine, series electric hybrid automobile will have efficiency comparable to a similar fuel cell hybrid automobile and will have fewer total emissions than the battery powered vehicle, even without a catalyst.
Todesco, Marco; Pascual, Mariana A; Owens, Gregory L; Ostevik, Katherine L; Moyers, Brook T; Hübner, Sariel; Heredia, Sylvia M; Hahn, Min A; Caseys, Celine; Bock, Dan G; Rieseberg, Loren H
2016-08-01
Hybridization may drive rare taxa to extinction through genetic swamping, where the rare form is replaced by hybrids, or by demographic swamping, where population growth rates are reduced due to the wasteful production of maladaptive hybrids. Conversely, hybridization may rescue the viability of small, inbred populations. Understanding the factors that contribute to destructive versus constructive outcomes of hybridization is key to managing conservation concerns. Here, we survey the literature for studies of hybridization and extinction to identify the ecological, evolutionary, and genetic factors that critically affect extinction risk through hybridization. We find that while extinction risk is highly situation dependent, genetic swamping is much more frequent than demographic swamping. In addition, human involvement is associated with increased risk and high reproductive isolation with reduced risk. Although climate change is predicted to increase the risk of hybridization-induced extinction, we find little empirical support for this prediction. Similarly, theoretical and experimental studies imply that genetic rescue through hybridization may be equally or more probable than demographic swamping, but our literature survey failed to support this claim. We conclude that halting the introduction of hybridization-prone exotics and restoring mature and diverse habitats that are resistant to hybrid establishment should be management priorities.
Separation control with fluidic oscillators in water
Schmidt, H.-J.; Woszidlo, R.; Nayeri, C. N.; Paschereit, C. O.
2017-08-01
The present study assesses the applicability of fluidic oscillators for separation control in water. The first part of this work evaluates the properties of the fluidic oscillators including frequency, cavitation effects, and exerted thrust. Derived from the governing internal dynamics, the oscillation frequency is found to scale directly with the jet's exit velocity and the size of the fluidic oscillator independent of the working fluid. Frequency data from various experiments collapse onto a single curve. The occurrence of cavitation is examined by visual inspection and hydrophone measurements. The oscillation frequency is not affected by cavitation because it does not occur inside the oscillators. The spectral information obtained with the hydrophone provide a reliable indicator for the onset of cavitation at the exit. The performance of the fluidic oscillators for separation control on a bluff body does not seem to be affected by the presence of cavitation. The thrust exerted by an array of fluidic oscillators with water as the working fluid is measured to be even larger than theoretically estimated values. The second part of the presented work compares the performance of fluidic oscillators for separation control in water with previous results in air. The array of fluidic oscillators is installed into the rear end of a bluff body model. The drag improvements based on force balance measurements agree well with previous wind tunnel experiments on the same model. The flow field is examined by pressure measurements and with particle image velocimetry. Similar performance and flow field characteristics are observed in both water and air.
Zhang, Jingjing; Luo, Yu; Shen, Xiaopeng; Maier, Stefan A; Cui, Tie Jun
2016-01-01
Plasmon hybridization between closely spaced nanoparticles yields new hybrid modes not found in individual constituents, allowing for the engineering of resonance properties and field enhancement capabilities of metallic nanostructure. Experimental verifications of plasmon hybridization have been thus far mostly limited to optical frequencies, as metals cannot support surface plasmons at longer wavelengths. Here, we introduce the concept of 'spoof plasmon hybridization' in highly conductive metal structures and investigate experimentally the interaction of localized surface plasmon resonances (LSPR) in adjacent metal disks corrugated with subwavelength spiral patterns. We show that the hybridization results in the splitting of spoof plasmon modes into bonding and antibonding resonances analogous to molecular orbital rule and plasmonic hybridization in optical spectrum. These hybrid modes can be manipulated to produce enormous field enhancements (larger than 5000) by tuning the separation between disks or alte...
Sawtooth Instability in the Compact Toroidal Hybrid
Herfindal, J. L.; Maurer, D. A.; Hartwell, G. J.; Ennis, D. A.; Knowlton, S. F.
2015-11-01
Sawtooth instabilities have been observed in the Compact Toroidal Hybrid (CTH), a current-carrying stellarator/tokamak hybrid device. The sawtooth instability is driven by ohmic heating of the core plasma until the safety factor drops below unity resulting in the growth of an m = 1 kink-tearing mode. Experiments varying the vacuum rotational transform from 0.02 to 0.13 are being conducted to study sawtooth property dependance on vacuum flux surface structure. The frequency of the sawtooth oscillations increase from 2 kHz to 2.8 kHz solely due the decrease in rise time of the oscillation, the crash time is unchanged. CTH has three two-color SXR cameras, a three-channel 1mm interferometer, and a new bolometer system capable of detecting the signatures of sawtooth instabilities. The new bolometer system consists of two cameras, each containing a pair of diode arrays viewing the plasma directly or through a beryllium filter. Electron temperature measurements are found with the two-color SXR cameras through a ratio of the SXR intensities. Impurity radiation can drastically affect the electron temperature measurement, therefore new filters consisting of aluminum and carbon were selected to avoid problematic line radiation while maximizing the signal for a 100 eV plasma. This work is supported by U.S. Department of Energy Grant No. DE-FG02-00ER54610.
He, Song
2017-04-01
Natural hybridization is reproduction (without artificial influence) between two or more species/populations which are distinguishable from each other by heritable characters. Natural hybridizations among marine fishes were highly underappreciated due to limited research effort; it seems that this phenomenon occurs more often than is commonly recognized. As hybridization plays an important role in biodiversity processes in the marine environment, detecting hybridization events and investigating hybridization is important to understand and protect biodiversity. The first chapter sets the framework for this disseration study. The Cohesion Species Concept was selected as the working definition of a species for this study as it can handle marine fish hybridization events. The concept does not require restrictive species boundaries. A general history and background of natural hybridization in marine fishes is reviewed during in chapter as well. Four marine fish hybridization cases were examed and documented in Chapters 2 to 5. In each case study, at least one diagnostic nuclear marker, screened from among ~14 candidate markers, was found to discriminate the putative hybridizing parent species. To further investigate genetic evidence to support the hybrid status for each hybrid offspring in each case, haploweb analysis on diagnostic markers (nuclear and/or mitochondrial) and the DAPC/PCA analysis on microsatellite data were used. By combining the genetic evidences, morphological traits, and ecological observations together, the potential reasons that triggered each hybridization events and the potential genetic/ecology effects could be discussed. In the last chapter, sequences from 82 pairs of hybridizing parents species (for which COI barcoding sequences were available either on GenBank or in our lab) were collected. By comparing the COI fragment p-distance between each hybridizing parent species, some general questions about marine fish hybridization were discussed: Is
Carnot cycle for an oscillator
Arnaud, Jacques; Chusseau, Laurent; Philippe, Fabrice
2002-09-01
In 1824 Carnot established that the efficiency of cyclic engines operating between a hot bath at absolute temperature Thot and a bath at a lower temperature Tcold cannot exceed 1 - Tcold/Thot. We show that linear oscillators alternately in contact with hot and cold baths obey this principle in the quantum as well as classical regime. The expression of the work performed is derived from a simple prescription. Reversible and non-reversible cycles are illustrated. The paper begins with historical considerations and is essentially self-contained.
Strange nonchaotic self-oscillator
Jalnine, Alexey Yu.; Kuznetsov, Sergey P.
2016-08-01
An example of strange nonchaotic attractor (SNA) is discussed in a dissipative system of mechanical nature driven by a constant torque applied to one of the elements of the construction. So the external force is not oscillatory, and the system is autonomous. Components of the motion with incommensurable frequencies emerge due to the irrational ratio of the sizes of the involved rotating elements. We regard the phenomenon as strange nonchaotic self-oscillations, and its existence sheds new light on the question of feasibility of SNA in autonomous systems.
Bruno Pontecorvo and Neutrino Oscillations
Directory of Open Access Journals (Sweden)
Samoil M. Bilenky
2013-01-01
Full Text Available I discuss briefly in this review, dedicated to the centenary of the birth of the great neutrino physicist Bruno Pontecorvo, the following ideas he proposed: (i the radiochemical method of neutrino detection; (ii the μ - e universality of the weak interaction; (iii the accelerator neutrino experiment which allowed to prove that muon and electron neutrinos are different particles (the Brookhaven experiment. I consider in some details Pontecorvo's pioneering idea of neutrino masses, mixing, and oscillations and the development of this idea by Pontecorvo, by Pontecorvo and Gribov, and by Pontecorvo and myself.
Neutrino Oscillation Studies with Reactors
Vogel, Petr; Zhang, Chao
2015-01-01
Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.
Making space for harmonic oscillators
Energy Technology Data Exchange (ETDEWEB)
Michelotti, Leo; /Fermilab
2004-11-01
If we restrict the number of harmonic oscillator energy eigenstates to some finite value, N, then the discrete spectrum of the corresponding position operator comprise the roots of the Hermite polynomial H{sub N+1}. Its range is just large enough to accommodate classical motion at high energy. A negative energy term must be added to the Hamiltonian which affects only the last eigenstate, |N>, suggesting it is concentrated at the extrema of this finite ''space''. Calculations support a conjecture that, in the limit of large N, the global distribution of points approaches the differential form for classical action.
Modeling of Coupled Chaotic Oscillators
Energy Technology Data Exchange (ETDEWEB)
Lai, Y. [Departments of Physics and Astronomy and of Mathematics, University of Kansas, Lawrence, Kansas 66045 (United States); Grebogi, C. [Institute for Plasma Research, Department of Mathematics, Institute for Physical Science and Technology, University of Maryland, College Park, Maryland 20742 (United States)
1999-06-01
Chaotic dynamics may impose severe limits to deterministic modeling by dynamical equations of natural systems. We give theoretical argument that severe modeling difficulties may occur for high-dimensional chaotic systems in the sense that no model is able to produce reasonably long solutions that are realized by nature. We make these ideas concrete by investigating systems of coupled chaotic oscillators. They arise in many situations of physical and biological interests, and they also arise from discretization of nonlinear partial differential equations. {copyright} {ital 1999} {ital The American Physical Society}
Quantizing the damped harmonic oscillator
Energy Technology Data Exchange (ETDEWEB)
Latimer, D C [Department of Physics and Astronomy, Vanderbilt University, Nashville, Tennessee 37235 (United States)
2005-03-04
We consider the Fermi quantization of the classical damped harmonic oscillator (dho). In past work on the subject, authors double the phase space of the dho in order to close the system at each moment in time. For an infinite-dimensional phase space, this method requires one to construct a representation of the CAR algebra for each time. We show that the unitary dilation of the contraction semigroup governing the dynamics of the system is a logical extension of the doubling procedure, and it allows one to avoid the mathematical difficulties encountered with the previous method.
Visual Grouping by Neural Oscillators
Yu, Guoshen
2008-01-01
Distributed synchronization is known to occur at several scales in the brain, and has been suggested as playing a key functional role in perceptual grouping. State-of-the-art visual grouping algorithms, however, seem to give comparatively little attention to neural synchronization analogies. Based on the framework of concurrent synchronization of dynamic systems, simple networks of neural oscillators coupled with diffusive connections are proposed to solve visual grouping problems. Multi-layer algorithms and feedback mechanisms are also studied. The same algorithm is shown to achieve promising results on several classical visual grouping problems, including point clustering, contour integration and image segmentation.
Wave Physics Oscillations - Solitons - Chaos
Nettel, Stephen
2009-01-01
This textbook is intended for those second year undergraduates in science and engineering who will later need an understanding of electromagnetic theory and quantum mechanics. The classical physics of oscillations and waves is developed at a more advanced level than has been customary for the second year, providing a basis for the quantum mechanics that follows. In this new edition the Green's function is explained, reinforcing the integration of quantum mechanics with classical physics. The text may also form the basis of an "introduction to theoretical physics" for physics majors. The concluding chapters give special attention to topics in current wave physics: nonlinear waves, solitons, and chaotic behavior.
Bloch oscillations in atom interferometry
Cladé, Pierre
2014-01-01
In Paris, we are using an atom interferometer to precisely measure the recoil velocity of an atom that absorbs a photon. In order to reach a high sensitivity, many recoils are transferred to atoms using the Bloch oscillations technique. In this lecture, I will present in details this technique and its application to high precision measurement. I will especially describe in details how this method allows us to perform an atom recoil measurement at the level of $1.3 \\times 10^{-9}$. This measurement is used in the most precise determination of the fine structure constant that is independent of quantum electrodynamics.
Ermakov approach for minisuperspace oscillators
Rosu, H C
1999-01-01
The WDW equation of arbitrary Hartle-Hawking factor ordering for several minisuperspace universe models, such as the pure gravity FRW and Taub ones, is mapped onto the dynamics of corresponding classical oscillators. The latter ones are studied by the classical Ermakov invariant method, which is a natural aproach in this context. For the more realistic case of a minimally coupled massive scalar field, one can study, within the same type of approach, the corresponding squeezing features as a possible means of describing cosmological evolution. Finally, we comment on the analogy with the accelerator physics
Magnus approximation in neutrino oscillations
Acero, Mario A.; Aguilar-Arevalo, Alexis A.; D'Olivo, J. C.
2011-04-01
Oscillations between active and sterile neutrinos remain as an open possibility to explain some anomalous experimental observations. In a four-neutrino (three active plus one sterile) mixing scheme, we use the Magnus expansion of the evolution operator to study the evolution of neutrino flavor amplitudes within the Earth. We apply this formalism to calculate the transition probabilities from active to sterile neutrinos with energies of the order of a few GeV, taking into account the matter effect for a varying terrestrial density.
Pair creation and plasma oscillations.
Energy Technology Data Exchange (ETDEWEB)
Prozorkevich, A. V.; Vinnik, D. V.; Schmidt, S. M.; Hecht, M. B.; Roberts, C. D.
2000-12-15
We describe aspects of particle creation in strong fields using a quantum kinetic equation with a relaxation-time approximation to the collision term. The strong electric background field is determined by solving Maxwell's equation in tandem with the Vlasov equation. Plasma oscillations appear as a result of feedback between the background field and the field generated by the particles produced. The plasma frequency depends on the strength of the initial background fields and the collision frequency, and is sensitive to the necessary momentum-dependence of dressed-parton masses.
Collective neutrino oscillations and spontaneous symmetry breaking
Duan, Huaiyu
2015-08-01
Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillations.
Lepton asymmetry and neutrino oscillations interplay
Energy Technology Data Exchange (ETDEWEB)
Kirilova, Daniela, E-mail: dani@astro.bas.bg [Bulgarian Academy of Sciences, Institute of Astronomy and NAO (Bulgaria)
2013-03-15
We discuss the interplay between lepton asymmetry L and {nu} oscillations in the early Universe. Neutrino oscillations may suppress or enhance previously existing L. On the other hand L is capable to suppress or enhance neutrino oscillations. The mechanism of L enhancement in MSW resonant {nu} oscillations in the early Universe is numerically analyzed. L cosmological effects through {nu} oscillations are discussed. We discuss how L may change the cosmological BBN constraints on neutrino and show that BBN model with {nu}{sub e}{r_reversible}{nu}{sub s} oscillations is extremely sensitive to L - it allows to obtain the most stringent constraints on L value. We discuss also the cosmological role of active-sterile {nu} mixing and L in connection with the indications about additional relativistic density in the early Universe, pointed out by BBN, CMB and LSS data and the analysis of global {nu} data.
Collective neutrino oscillations and spontaneous symmetry breaking
Duan, Huaiyu
2015-01-01
Neutrino oscillations in a hot and dense astrophysical environment such as a core-collapse supernova pose a challenging, seven-dimensional flavor transport problem. To make the problem even more difficult (and interesting), neutrinos can experience collective oscillations through nonlinear refraction in the dense neutrino medium in this environment. Significant progress has been made in the last decade towards the understanding of collective neutrino oscillations in various simplified neutrino gas models with imposed symmetries and reduced dimensions. However, a series of recent studies seem to have "reset" this progress by showing that these models may not be compatible with collective neutrino oscillations because the latter can break the symmetries spontaneously if they are not imposed. We review some of the key concepts of collective neutrino oscillations by using a few simple toy models. We also elucidate the breaking of spatial and directional symmetries in these models because of collective oscillation...
Phase noise and frequency stability in oscillators
Rubiola, Enrico
2009-01-01
Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...
Damped transverse oscillations of interacting coronal loops
Soler, Roberto
2015-01-01
Damped transverse oscillations of magnetic loops are routinely observed in the solar corona. This phenomenon is interpreted as standing kink magnetohydrodynamic waves, which are damped by resonant absorption owing to plasma inhomogeneity across the magnetic field. The periods and damping times of these oscillations can be used to probe the physical conditions of the coronal medium. Some observations suggest that interaction between neighboring oscillating loops in an active region may be important and can modify the properties of the oscillations compared to those of an isolated loop. Here we theoretically investigate resonantly damped transverse oscillations of interacting non-uniform coronal loops. We provide a semi-analytic method, based on the T-matrix theory of scattering, to compute the frequencies and damping rates of collective oscillations of an arbitrary configuration of parallel cylindrical loops. The effect of resonant damping is included in the T-matrix scheme in the thin boundary approximation. ...
Entangled states of spin and clock oscillators
Polzik, Eugene
2016-05-01
Measurements of one quadrature of an oscillator with precision beyond its vacuum state uncertainty have occupied a central place in quantum physics for decades. We have recently reported the first experimental implementation of such measurement with a magnetic oscillator. However, a much more intriguing goal is to trace an oscillator trajectory with the precision beyond the vacuum state uncertainty in both position and momentum, a feat naively assumed not possible due to the Heisenberg uncertainty principle. We have demonstrated that such measurement is possible if the oscillator is entangled with a quantum reference oscillator with an effective negative mass. The key element is the cancellation of the back action of the measurement on the composite system of two oscillators. Applications include measurements of e.-m. fields, accelleration, force and time with practically unlimited accuracy. In a more general sense, this approach leads to trajectories without quantum uncertainties and to achieving new fundamental bounds on the measurement precision.
Characterizing correlations of flow oscillations at bottlenecks
Kretz, Tobias; Wölki, Marko; Schreckenberg, Michael
2006-02-01
'Oscillations' occur in quite different kinds of many-particle systems when two groups of particles with different directions of motion meet or intersect at a certain spot. In this work a model of pedestrian motion is presented that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to include observables that can be used to characterize different kinds of oscillations.
Characterizing correlations of flow oscillations at bottlenecks
Kretz, Tobias; Woelki, Marko; Schreckenberg, Michael
2006-01-01
"Oscillations" occur in quite different kinds of many-particle-systems when two groups of particles with different directions of motion meet or intersect at a certain spot. We present a model of pedestrian motion that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to hold observables that can be used to characterize different kinds of oscillations.
Dynamics-Enabled Nanoelectromechanical Systems (NEMS) Oscillators
2014-06-01
Frequency (both quantities scaled) for a Duffing type heavily-saturated Oscillator (The red dots (Yurke points) satisfy Ω/Δ = 0 (incidentally, also Ω...operating in the vicinity of the second instability point of a Duffing oscillator . This will be described below. Further, we explored a wide range of...fluctuation processes. This is clearly depicted for operation at what we term a Kenig point of a Duffing oscillator , as shown in Figure 3. The
Sum rules in the oscillator radiation processes
Energy Technology Data Exchange (ETDEWEB)
Casana, R. [Instituto de Fisica Teorica-IFT/UNESP, Rua Pamplona 145, 01405-900 Sao Paulo, SP (Brazil)]. E-mail: casana@ift.unesp.br; Flores-Hidalgo, G. [Instituto de Fisica Teorica-IFT/UNESP, Rua Pamplona 145, 01405-900 Sao Paulo, SP (Brazil)]. E-mail: gflores@ift.unesp.br; Pimentel, B.M. [Instituto de Fisica Teorica-IFT/UNESP, Rua Pamplona 145, 01405-900 Sao Paulo, SP (Brazil)]. E-mail: pimentel@ift.unesp.br
2005-03-28
We consider the problem of a harmonic oscillator coupled to a scalar field in the framework of recently introduced dressed coordinates. We compute all the probabilities associated with the decay process of an excited level of the oscillator. Instead of doing direct quantum mechanical calculations we establish some sum rules from which we infer the probabilities associated to the different decay processes of the oscillator. Thus, the sum rules allows to show that the transition probabilities between excited levels follow a binomial distribution.
Sum rules in the oscillator radiation processes
Casana, R.; Flores-Hidalgo, G.; Pimentel, B. M.
2005-03-01
We consider the problem of a harmonic oscillator coupled to a scalar field in the framework of recently introduced dressed coordinates. We compute all the probabilities associated with the decay process of an excited level of the oscillator. Instead of doing direct quantum mechanical calculations we establish some sum rules from which we infer the probabilities associated to the different decay processes of the oscillator. Thus, the sum rules allows to show that the transition probabilities between excited levels follow a binomial distribution.
Optical realization of the dissipative quantum oscillator
Longhi, Stefano
2016-01-01
An optical realization of the damped quantum oscillator, based on transverse light dynamics in an optical resonator with slowly-moving mirrors, is theoretically suggested. The optical resonator setting provides a simple implementation of the time-dependent Caldirola-Kanai Hamiltonian of the dissipative quantum oscillator, and enables to visualize the effects of damped oscillations in the classical (ray optics) limit and wave packet collapse in the quantum (wave optics) regime.
FORCED OSCILLATIONS IN NONLINEAR FEEDBACK CONTROL SYSTEM
Since a nonlinear feedback control system may possess more than one type of forced oscillations, it is highly desirable to investigate the type of...method for finding the existence of forced oscillations and response curve characteristics of a nonlinear feedback control system by means of finding the...second order feedback control system are investigated; the fundamental frequency forced oscillation for a higher order system and the jump resonance
Desynchronization of stochastically synchronized chemical oscillators
Energy Technology Data Exchange (ETDEWEB)
Snari, Razan; Tinsley, Mark R., E-mail: mark.tinsley@mail.wvu.edu, E-mail: kshowalt@wvu.edu; Faramarzi, Sadegh; Showalter, Kenneth, E-mail: mark.tinsley@mail.wvu.edu, E-mail: kshowalt@wvu.edu [C. Eugene Bennett Department of Chemistry, West Virginia University, Morgantown, West Virginia 26506-6045 (United States); Wilson, Dan; Moehlis, Jeff [Department of Mechanical Engineering, University of California, Santa Barbara, California 93106 (United States); Netoff, Theoden Ivan [Department of Biomedical Engineering, University of Minnesota, Minneapolis, Minnesota 55455 (United States)
2015-12-15
Experimental and theoretical studies are presented on the design of perturbations that enhance desynchronization in populations of oscillators that are synchronized by periodic entrainment. A phase reduction approach is used to determine optimal perturbation timing based upon experimentally measured phase response curves. The effectiveness of the perturbation waveforms is tested experimentally in populations of periodically and stochastically synchronized chemical oscillators. The relevance of the approach to therapeutic methods for disrupting phase coherence in groups of stochastically synchronized neuronal oscillators is discussed.
Bloch oscillations of path-entangled photons.
Bromberg, Yaron; Lahini, Yoav; Silberberg, Yaron
2010-12-31
We show that when photons in N-particle path-entangled |N,0)+|0,N) or N00N states undergo Bloch oscillations, they exhibit a periodic transition between spatially bunched and antibunched states. The period of the bunching-antibunching oscillation is N times faster than the period of the oscillation of the photon density, manifesting the unique coherence properties of N00N states. The transition occurs even when the photons are well separated in space.
Non-Newtonian mechanics of oscillation centers
Dodin, I. Y.; Fisch, N. J.
2008-10-01
Classical particles oscillating in high-frequency or static fields effectively exhibit a modified rest mass meff which determines the oscillation center motion. Unlike the true mass, meff depends on the field parameters and can be a nonanalytic function of the particle average velocity and the oscillation energy; hence non-Newtonian "metaplasmas" that permit a new type of plasma maser, signal rectification, frequency doubling, and one-way walls.
Linearization of the Relativistic Oscillator Hierarchy
Anderson, Robert L
2016-01-01
This paper is based on MacColl's [1] solution of the equation of motion for a linear (harmonic) oscillator subject to the laws of special relativity in the rest frame of the center of attraction. MacColl's result can be extended to the quartic oscillator in this frame with one extremely simple adjustment of the linearization map given in Anderson [2]. In fact, it can be extended to all the attractive oscillators in this frame.
Stimulated scattering in strongly coupled nanolasers induced by Rabi oscillations
Marconi, Mathias; Raineri, Fabrice; Levenson, Ariel; Yacomotti, Alejandro M
2016-01-01
Two coupled-cavity systems, or "photonic dimers", are efficient test-beds for both fundamental optics -the realization of quantum correlated states, Josephson physics, and so forth-, and applications such as optical flip-flop memories. In this work we report on the first observation of nonlinear mode interaction in a photonic dimer formed by two semiconductor photonic crystal coupled nanolasers. For this, we investigate energy transfer between hybrid modes, which manifests as a switching from the blue-detuned (bonding) to the red-detuned (anti-bonding) modes. An mean-field model allows us to explain this phenomenon as stimulated scattering due to carrier population oscillations in the cavities at the Rabi frequency. Such asymmetrical mode interaction is universal in semiconductor laser photonic molecules, and unveils the origin of cross-correlation dips in the statistics of mode fluctuations.
Local random phase approximation with projected oscillator orbitals
Mussard, Bastien
2015-01-01
An approximation to the many-body London dispersion energy in molecular systems is expressed as a functional of the occupied orbitals only. The method is based on the local-RPA theory. The occupied orbitals are localized molecular orbitals and the virtual space is described by projected oscillator orbitals, i.e. functions obtained by multiplying occupied localized orbitals with solid spherical harmonic polynomials having their origin at the orbital centroids. Since we are interested in the long-range part of the correlation energy, responsible for dispersion forces, the electron repulsion is approximated by its multipolar expansion. This procedure leads to a fully non-empirical long-range correlation energy expression. Molecular dispersion coefficients calculated from determinant wave functions obtained by a range-separated hybrid method reproduce experimental values with less than 15% error.
Transient analysis of microwave Gunn oscillator using extended spectral element time domain method
Xu, Kan; Chen, Rushan; Sheng, Yijun; Fu, Ping; Chen, Chuan; Yan, Qingshang; Yu, Yanyan
2011-10-01
In this study, the microwave Gunn oscillator is analyzed by a hybrid electromagnetic circuit simulator, which is based on the spectral element time domain (SETD) method. The Gunn diode within the oscillator is treated as a lumped element, while the passive distributed part of the oscillator is modeled using the SETD method. In order to incorporate the contribution of the Gunn diode into the SETD context, the SETD method is extended by introducing a lumped current term into the second-order vector wave equation. When Galerkin's method is used for the space discretization and the central difference scheme is used for time stepping, a global SETD system involving the Gunn diode is assembled. Furthermore, the global system matrix is block-diagonal and the inversion of this matrix can be easily implemented, and thus the extended SETD method is a fully explicit solver and CPU time can be significantly reduced. By virtue of this method, the strong nonlinear feature of the Gunn oscillator is well characterized in the time domain, such as the phenomenon of injection locking. Numerical results demonstrate the ability and effectiveness of the extended SETD method for the fast analysis of microwave Gunn oscillator.
Dynamics of Coupled Quantum-Classical Oscillators
Institute of Scientific and Technical Information of China (English)
HE Wei-Zhong; XU Liu-Su; ZOU Feng-Wu
2004-01-01
@@ The dynamics of systems consisting of coupled quantum-classical oscillators is numerically investigated. It is shown that, under certain conditions, the quantum oscillator exhibits chaos. When the mass of the classical oscillator increases, the chaos will be suppressed; if the energy of the system and/or the coupling strength between the two oscillators increases, chaotic behaviour of the system appears. This result will be helpful to understand the probability of the emergence of quantum chaos and may be applied to explain the spectra of complex atoms qualitatively.
Quantum oscillations in superconductors in magnetic field
Gvozdikov, Vladimir M.; Gvozdikova, Mariya V.
2000-07-01
The Aharonov-Bohm oscillations (ABO) of the free energy, the critical temperature, and the magnetic susceptibility in a stack of hollow mesoscopic cylinders are calculated. It is shown that sinusoidal (in flux) ABO crosses over to the parabolic Little-Parks oscillations (LPO) when the diameter of cylinders exceeds the coherence length. The exponential temperature behaviour of the magnetic susceptibility is like that found in Ag cylinders with thin Nb coating [Czech. J. Physics 46 (1996) 2317]. The formal analogy between oscillations of the free energy in the Aharonov-Bohm system in question and the de Haas-van Alphen oscillations (dHvAO) in layered superconductors is discussed.
Coupled oscillators with parity-time symmetry
Tsoy, Eduard N.
2017-02-01
Different models of coupled oscillators with parity-time (PT) symmetry are studied. Hamiltonian functions for two and three linear oscillators coupled via coordinates and accelerations are derived. Regions of stable dynamics for two coupled oscillators are obtained. It is found that in some cases, an increase of the gain-loss parameter can stabilize the system. A family of Hamiltonians for two coupled nonlinear oscillators with PT-symmetry is obtained. An extension to high-dimensional PT-symmetric systems is discussed.
Comparison of Methods for Oscillation Detection
DEFF Research Database (Denmark)
Odgaard, Peter Fogh; Trangbæk, Klaus
2006-01-01
This paper compares a selection of methods for detecting oscillations in control loops. The methods are tested on measurement data from a coal-fired power plant, where some oscillations are occurring. Emphasis is put on being able to detect oscillations without having a system model and without u...... using process knowledge. The tested methods show potential for detecting the oscillations, however, transient components in the signals cause false detections as well, motivating usage of models in order to remove the expected signals behavior....
Quantum entanglement of Pais-Uhlenbeck oscillators
Dimov, Hristo; Rashkov, Radoslav C; Vetsov, Tsvetan
2016-01-01
We study the quantum entanglement of coupled Pais-Uhlenbeck oscillators using the formalism of thermo-field dynamics. The entanglement entropy is computed for the specific cases of two and a ring of $N$ coupled Pais-Uhlenbeck oscillators of fourth order. It is shown that the entanglement entropy depends on the temperatures, frequencies and coupling parameters of the different degrees of freedom corresponding to harmonic oscillators. Finally, we advert to the information geometry theory by calculating the Fisher information metric for the considered system of coupled oscillators.
CPT-Odd resonances in neutrino oscillations
Barger; Pakvasa; Weiler; Whisnant
2000-12-11
We consider the consequences for future neutrino factory experiments of small CPT-odd interactions in neutrino oscillations. The nu(&mgr;)-->nu(&mgr;) and nu;(&mgr;)-->nu;(&mgr;) survival probabilities at a baseline L = 732 km can test for CPT-odd contributions at orders of magnitude better sensitivity than present neutrino sector limits. Interference between the CPT-violating interaction and CPT-even mass terms in the Lagrangian can lead to a resonant enhancement of the oscillation amplitude. For oscillations in matter, a simultaneous enhancement of both neutrino and antineutrino oscillation amplitudes is possible.
Scleronomic holonomic constraints and conservative nonlinear oscillators
Energy Technology Data Exchange (ETDEWEB)
Munoz, R; Gonzalez-Garcia, G; Izquierdo-De La Cruz, E Izquierdo-De La [Universidad Autonoma de la Ciudad de Mexico, Centro Historico, Fray Servando Teresa de Mier 92, Col Centro, Del Cuauhtemoc, Mexico DF, CP 06080 (Mexico); Fernandez-Anaya, G, E-mail: rodrigo.munoz@uacm.edu.mx, E-mail: gggharper@gmail.com, E-mail: erickidc@gmail.com, E-mail: guillermo.fernandez@uia.mx [Universidad Iberoamericana, Departamento de Fisica y Matematicas, Prolongacon Paseo de de la Reforma 880, Col Lomas de Santa Fe, Del Alvaro Obregn, Mexico DF, CP 01219 (Mexico)
2011-05-15
A bead sliding, under the sole influence of its own weight, on a rigid wire shaped in the fashion of a plane curve, will describe (generally anharmonic) oscillations around a local minimum. For given shapes, the bead will behave as a harmonic oscillator in the whole range, such as an unforced, undamped, Duffing oscillator, etc. We also present cases in which the effective potential acting on the bead is not analytical around a minimum. The small oscillation approximation cannot be applied to such pathological cases. Nonetheless, these latter instances are studied with other standard techniques.
High Reliability Oscillators for Terahertz Systems Project
National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...
Energetics of Synchronization in Coupled Oscillators
Izumida, Yuki; Seifert, Udo
2016-01-01
We formulate the energetics of synchronization in coupled oscillators by unifying the nonequilibrium aspects with the nonlinear dynamics via stochastic thermodynamics. We derive a concise and universal expression of the energy dissipation rate using nonlinear-dynamics quantities characterizing synchronization, and elucidate how synchronization/desynchronization between the oscillators affects it. We apply our theory to hydrodynamically-coupled Stokes spheres rotating on circular trajectories that may be interpreted as the simplest model of synchronization of coupled oscillators in a biological system, revealing that the oscillators gain the ability to do more work on the surrounding fluid as the degree of phase synchronization increases.
Electronically tunable phase locked loop oscillator
Balasis, M.; Davis, M. R.; Jackson, C. R.
1982-02-01
This report describes the design and development of a low noise, high power, variable oscillator incorporating a high 'Q' electronically tunable resonator as the frequency determining element. The VCO provides improved EMC performance in phase locked synthesizers which are a part of communications equipments. The oscillator combines a low noise VMOS transistor with the selectivity and out-of-band attenuation of a coaxial resonator to provide superior EMC performance. Several oscillator designs were examined and the basis for the final configuration is presented. Oscillator noise is discussed and models for analysis are explained. A brass board model was constructed and tested and the technical results are presented.
On Oscillations in the Social Force Model
Kretz, Tobias
2015-01-01
The Social Force Model is one of the most prominent models of pedestrian dynamics. As such naturally much discussion and criticism has spawned around it, some of which concerns the existence of oscillations in the movement of pedestrians. This contribution is investigating under which circumstances, parameter choices, and model variants oscillations do occur and how this can be prevented. It is shown that oscillations can be excluded if the model parameters fulfill certain relations. The fact that with some parameter choices oscillations occur and with some not is exploited to verify a specific computer implementation of the model.
Optimal parameters uncoupling vibration modes of oscillators
Le, K. C.; Pieper, A.
2017-07-01
This paper proposes a novel optimization concept for an oscillator with two degrees of freedom. By using specially defined motion ratios, we control the action of springs to each degree of freedom of the oscillator. We aim at showing that, if the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized among all admissible parameters and motions satisfying Lagrange's equations, then the optimal motion ratios uncouple vibration modes. A similar result holds true for the dissipative oscillator having dampers. The application to optimal design of vehicle suspension is discussed.
Optimal parameters uncoupling vibration modes of oscillators
Le, Khanh Chau
2016-01-01
A novel optimization concept for an oscillator with two degrees of freedom is proposed. By using specially defined motion ratios, we control the action of springs and dampers to each degree of freedom of the oscillator. If the potential action of the springs in one period of vibration, used as the payoff function for the conservative oscillator, is maximized, then the optimal motion ratios uncouple vibration modes. The same result holds true for the dissipative oscillator. The application to optimal design of vehicle suspension is discussed.
Introduction to classical and quantum harmonic oscillators
Bloch, Sylvan C
2013-01-01
From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con
Waves and oscillations in nature an introduction
Narayanan, A Satya
2015-01-01
Waves and oscillations are found in large scales (galactic) and microscopic scales (neutrino) in nature. Their dynamics and behavior heavily depend on the type of medium through which they propagate.Waves and Oscillations in Nature: An Introduction clearly elucidates the dynamics and behavior of waves and oscillations in various mediums. It presents different types of waves and oscillations that can be observed and studied from macroscopic to microscopic scales. The book provides a thorough introduction for researchers and graduate students in assorted areas of physics, such as fluid dynamics,
Kozai-Lidov Oscillations of Circumstellar Disks
Lubow, Stephen H.; Fu, Wen; Martin, Rebecca G.
2015-01-01
It has been known for over 50 years that the orbit of an object in a binary system can undergo strong tilt and eccentricity oscillations. This effect, known as the Kozai-Lidov effect, may explain several observed astronomical phenomena, including the high eccentricities observed for some extra-solar planets. Martin et al. 2014 recently reported simulation results showing that fluid disks can undergo Kozai-Lidov oscillations. Such oscillations can have important consequences on disk and planet evolution. We have continued investigating the conditions for which such oscillations are possible.
Oscillating systems with cointegrated phase processes
DEFF Research Database (Denmark)
Østergaard, Jacob; Rahbek, Anders; Ditlevsen, Susanne
2017-01-01
We present cointegration analysis as a method to infer the network structure of a linearly phase coupled oscillating system. By defining a class of oscillating systems with interacting phases, we derive a data generating process where we can specify the coupling structure of a network that resemb......We present cointegration analysis as a method to infer the network structure of a linearly phase coupled oscillating system. By defining a class of oscillating systems with interacting phases, we derive a data generating process where we can specify the coupling structure of a network...
Neutrino Oscillations: A Global Analysis
Fogli, G L; Marrone, A; Montanino, D; Palazzo, A; Rotunno, A M
2003-01-01
We review the status of the neutrino oscillation physics (as of June 2003), with a particular emphasis on the present knowledge of the neutrino mass-mixing parameters in a three generation approach. We consider first the nu_mu-->nu_tau flavor transitions of atmospheric neutrinos. It is found that standard oscillations provide the best description of the SK+K2K data, and that the associated mass-mixing parameters are determined at 1 sigma (and dof=1) as: Delta m^2=(2.6 +-0.4) x 10^-3 eV^2 and sin^2(2theta)=1.00+0.00-0.05. Such indications, presently dominated by SK, could be strengthened by further K2K data. Then we analyze the energy spectrum of reactor neutrino events recently observed at KamLAND and combine them with solar and terrestrial neutrino data. We find that the solution to the solar neutrino problem at large mixing angle (LMA) is basically split into two sub-regions, that we denote as LMA-I and LMA-II. The LMA-I solution, characterized by lower values of the squared neutrino mass gap, is favored by...
Microdroplet oscillations during optical pulling
Ellingsen, Simen Å
2011-01-01
It was recently shown theoretically that it is possible to pull a spherical dielectric body towards the source of a laser beam [Nature Photonics {\\bf 5}, 531 (2011)], a result with immediate consequences to optical manipulation of small droplets. Optical pulling can be realised e.g.\\ using a diffraction free Bessel beam, and is expected to be of great importance in manipulation of microscopic droplets in micro- and nanofluidics. Compared to conventional optical pushing, however, the radio of optical net force to stress acting on a droplet is much smaller, increasing the importance of oscillations. We describe the time-dependent surface deformations of a water microdroplet under optical pulling to linear order in the deformation. Shape oscillations have a lifetime in the order of microseconds for droplet radii of a few micrometers. The force density acting on the initially spherical droplet is strongly peaked near the poles on the beam axis, causing the deformations to take the form of jet-like protrusions.
Cardiogenic oscillation induced ventilator autotriggering
Directory of Open Access Journals (Sweden)
Narender Kaloria
2015-01-01
Full Text Available Cardiogenic oscillation during mechanical ventilation can auto-trigger the ventilator resembling patient initiated breadth. This gives a false sense of intact respiratory drive and determination brain death, even if other tests are positive, is not appropriate in such a situation. It will prolong the ICU stay and confound the brain-death determination. In this case report, we describe a 35 year old man who was brought to the hospital after many hours of critical delay following multiple gun shot injuries. The patient suffered a cardiac arrest while on the way from another hospital. After an emergency laparotomy, patient was shifted to Intensive Care Unit (ICU with Glasgow Coma Scale (GCS score of E1VTM1 and was mechanically ventilated. Despite absence of brainstem reflexes, the ventilator continued to be triggered on continuous positive airway pressure (CPAP mode and the patient maintained normal oxygen saturation and acceptable levels of carbon dioxide. An apnoea test confirmed absent respiratory drive. Ventilatory waveform graph analysis, revealed cardiogenic oscillation as the cause for autotrigerring.
Oscillating layer thickness and vortices generated in oscillation of finite plate
Sin, V. K.; Wong, I. K.
2016-06-01
Moving mesh strategy is used in the model of flow induced by oscillating finite plate through software - COMSOL Multiphysics. Flow is assumed to be laminar and arbitrary Lagrangian-Eulerian method is used for moving mesh in the simulation. Oscillating layer thickness is found which is different from the analytical solution by 2 to 3 times depends on the oscillating frequency. Vortices are also observed near the oscillating finite plate because of the edge effect of the finite plate.
DEFF Research Database (Denmark)
Blackburn, Patrick Rowan; Huertas, Antonia; Manzano, Maria;
2014-01-01
Leon Henkin was not a modal logician, but there is a branch of modal logic that has been deeply influenced by his work. That branch is hybrid logic, a family of logics that extend orthodox modal logic with special proposition symbols (called nominals) that name worlds. This paper explains why...... Henkin’s techniques are so important in hybrid logic. We do so by proving a completeness result for a hybrid type theory called HTT, probably the strongest hybrid logic that has yet been explored. Our completeness result builds on earlier work with a system called BHTT, or basic hybrid type theory...... is due to the first-order perspective, which lies at the heart of Henin’s best known work and hybrid logic....
Stirring and mixing effects on oscillations and inhomogeneities in the minimal bromate oscillator
Dutt, A. K.; Menzinger, M.
1999-04-01
Stirring and mixing effects on the oscillations and inhomogeneities in the bromate-bromide-cerous system (minimal bromate oscillator) have been investigated in a continuously fed stirred tank reactor (CSTR). A movable microelectrode is used to monitor the inhomogeneities inside the CSTR in an oscillating phase. The results are explained in terms of the theory of imperfect mixing.
Discrete Parametric Oscillation and Nondiffracting Beams in a Glauber-Fock Oscillator
Oztas, Z
2016-01-01
We consider a Glauber-Fock oscillator and show that diffraction can be managed. We show how to design arrays of waveguides where light beams experience zero diffraction. We find an exact analytical family of nondiffracting localized solution. We predict discrete parametric oscillation in the Glauber-Fock oscillator.
BSA Hybrid Synthesized Polymer
Institute of Scientific and Technical Information of China (English)
Zong Bin LIU; Xiao Pei DENG; Chang Sheng ZHAO
2006-01-01
Bovine serum albumin (BSA), a naturally occurring biopolymer, was regarded as a polymeric material to graft to an acrylic acid (AA)-N-vinyl pyrrolidone (NVP) copolymer to form a biomacromolecular hybrid polymer. The hybrid polymer can be blended with polyethersulfone (PES) to increase the hydrophilicity of the PES membrane, which suggested that the hybrid polymer might have a wide application in the modification of biomaterials.
DEFF Research Database (Denmark)
Ronkko, Mauno; Ravn, Anders P.
1997-01-01
a differential action, which allows differential equations as primitive actions. The extension allows us to model hybrid systems with both continuous and discrete behaviour. The main result of this paper is an extension of such a hybrid action system with parallel composition. The extension does not change...... the original meaning of the parallel composition, and therefore also the ordinary action systems can be composed in parallel with the hybrid action systems....
Directory of Open Access Journals (Sweden)
V. Dvadnenko
2016-06-01
Full Text Available The hybrid vehicle control system includes a start–stop system for an internal combustion engine. The system works in a hybrid mode and normal vehicle operation. To simplify the start–stop system, there were user new possibilities of a hybrid car, which appeared after the conversion. Results of the circuit design of the proposed system of basic blocks are analyzed.
Nanoscale Organic Hybrid Electrolytes
Nugent, Jennifer L.
2010-08-20
Nanoscale organic hybrid electrolytes are composed of organic-inorganic hybrid nanostructures, each with a metal oxide or metallic nanoparticle core densely grafted with an ion-conducting polyethylene glycol corona - doped with lithium salt. These materials form novel solvent-free hybrid electrolytes that are particle-rich, soft glasses at room temperature; yet manifest high ionic conductivity and good electrochemical stability above 5V. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Hybrid radiator cooling system
France, David M.; Smith, David S.; Yu, Wenhua; Routbort, Jules L.
2016-03-15
A method and hybrid radiator-cooling apparatus for implementing enhanced radiator-cooling are provided. The hybrid radiator-cooling apparatus includes an air-side finned surface for air cooling; an elongated vertically extending surface extending outwardly from the air-side finned surface on a downstream air-side of the hybrid radiator; and a water supply for selectively providing evaporative cooling with water flow by gravity on the elongated vertically extending surface.
Hybrid Unifying Variable Supernetwork Model
Institute of Scientific and Technical Information of China (English)
LIU; Qiang; FANG; Jin-qing; LI; Yong
2015-01-01
In order to compare new phenomenon of topology change,evolution,hybrid ratio and network characteristics of unified hybrid network theoretical model with unified hybrid supernetwork model,this paper constructed unified hybrid variable supernetwork model(HUVSM).The first layer introduces a hybrid ratio dr,the
Large Unifying Hybrid Supernetwork Model
Institute of Scientific and Technical Information of China (English)
LIU; Qiang; FANG; Jin-qing; LI; Yong
2015-01-01
For depicting multi-hybrid process,large unifying hybrid network model(so called LUHNM)has two sub-hybrid ratios except dr.They are deterministic hybrid ratio(so called fd)and random hybrid ratio(so called gr),respectively.
National Research Council Canada - National Science Library
Sankaran Venugopal; K K Rajesh; V Ramanujachari
2011-01-01
With their unique operational characteristics, hybrid rockets can potentially provide safer, lower-cost avenues for spacecraft and missiles than the current solid propellant and liquid propellant systems...
National Aeronautics and Space Administration — Armstrong researchers are continuing their efforts to further develop FOSS technologies. A hybrid FOSS technique (HyFOSS) employs conventional continuous grating...
From hybrid swarms to swarms of hybrids
Stohlgren, Thomas J.; Szalanski, Allen L; Gaskin, John F.; Young, Nicholas E.; West, Amanda; Jarnevich, Catherine S.; Tripodi, Amber
2015-01-01
Science has shown that the introgression or hybridization of modern humans (Homo sapiens) with Neanderthals up to 40,000 YBP may have led to the swarm of modern humans on earth. However, there is little doubt that modern trade and transportation in support of the humans has continued to introduce additional species, genotypes, and hybrids to every country on the globe. We assessed the utility of species distributions modeling of genotypes to assess the risk of current and future invaders. We evaluated 93 locations of the genus Tamarix for which genetic data were available. Maxent models of habitat suitability showed that the hybrid, T. ramosissima x T. chinensis, was slightly greater than the parent taxa (AUCs > 0.83). General linear models of Africanized honey bees, a hybrid cross of Tanzanian Apis mellifera scutellata and a variety of European honey bee including A. m. ligustica, showed that the Africanized bees (AUC = 0.81) may be displacing European honey bees (AUC > 0.76) over large areas of the southwestern U.S. More important, Maxent modeling of sub-populations (A1 and A26 mitotypes based on mDNA) could be accurately modeled (AUC > 0.9), and they responded differently to environmental drivers. This suggests that rapid evolutionary change may be underway in the Africanized bees, allowing the bees to spread into new areas and extending their total range. Protecting native species and ecosystems may benefit from risk maps of harmful invasive species, hybrids, and genotypes.
Institute of Scientific and Technical Information of China (English)
无
2006-01-01
Earlier studies have shown that various stimuli can induce specific cytosolic calcium ([Ca2+]cyt) oscillations in guard cells and various oscillations in stomatal apertures. Exactly how [Ca2+]cyt oscillation signaling functions in stomatal oscillation is not known. In the present study, the epidermis of broad bean (Vicia faba L.)was used and a rapid ion-exchange treatment with two shifting buffers differing in K+ and Ca2+ concentrations was applied. The treatment for five transients at a 10-min transient period induced clear and regular stomatal oscillation. However, for other transient numbers and periods, the treatments induced some irregular oscillations or even no obvious oscillations in stomatal aperture. The results indicate that stomatal oscillation is encoded by parameter-specific [Ca2+]cyt oscillation: the parameters of [Ca2+]cyt oscillation affected the occurrence rate and the parameters of stomatal oscillation. The water channel inhibitor HgCl2 completely inhibited stomatal oscillation and the inhibitory effect could be partially reversed by β-mercaptoethanol (an agent capable of reversing water channel inhibition by HgCl2). Other inhibitory treatments against ion transport (i.e. the application of LaCl3, EGTA, or tetraethylammonium chloride (TEACl))weakly impaired stomatal oscillation when the compounds were added after rapid ion-exchange treatment.If these compounds were added before rapid-ion exchange treatment, the inhibitory effect was much more apparent (except in the case of TEACI). The results of the present study suggest that water channels are involved in stomatal oscillation as a downstream element of [Ca2+]cyt oscillation signaling.
Triple Hybrid Energy Harvesting Interface Electronics
Uluşan, H.; Chamanian, S.; Pathirana, W. M. P. R.; Zorlu, Ö.; Muhtaroğlu, A.; Külah, H.
2016-11-01
This study presents a novel triple hybrid system that combines simultaneously generated power from thermoelectric (TE), vibration-based electromagnetic (EM) and piezoelectric (PZT) harvesters for a relatively high power supply capability. In the proposed solution each harvesting source utilizes a distinct power management circuit that generates a DC voltage suitable for combining the three parallel supplies. The circuits are designed and implemented in 180 nm standard CMOS technology, and are terminated with a schottky diode to avoid reverse current flow. The harvested AC signal from the EM harvester is rectified with a self-powered AC-DC doubler, which utilizes active diode structures to minimize the forward- bias voltage drop. The PZT interface electronics utilizes a negative voltage converter as the first stage, followed by synchronous power extraction and DC-to-DC conversion through internal switches, and an external inductor. The ultra-low voltage DC power harvested by the TE generator is stepped up through a charge-pump driven by an LC oscillator with fully- integrated center-tapped differential inductors. Test results indicate that hybrid energy harvesting circuit provides more than 1 V output for load resistances higher than 100 kΩ (10 μW) where the stand-alone harvesting circuits are not able to reach 1 V output. This is the first hybrid harvester circuit that simultaneously extracts energy from three independent sources, and delivers a single DC output.
Kravchuk functions for the finite oscillator approximation
Atakishiyev, Natig M.; Wolf, Kurt Bernardo
1995-01-01
Kravchuk orthogonal functions - Kravchuk polynomials multiplied by the square root of the weight function - simplify the inversion algorithm for the analysis of discrete, finite signals in harmonic oscillator components. They can be regarded as the best approximation set. As the number of sampling points increases, the Kravchuk expansion becomes the standard oscillator expansion.
Simple Optoelectronic Feedback in Microwave Oscillators
Maleki, Lute; Iltchenko, Vladimir
2009-01-01
A proposed method of stabilizing microwave and millimeter-wave oscillators calls for the use of feedback in optoelectronic delay lines characterized by high values of the resonance quality factor (Q). The method would extend the applicability of optoelectronic feedback beyond the previously reported class of optoelectronic oscillators that comprise two-port electronic amplifiers in closed loops with high-Q feedback circuits.
Damping of Crank–Nicolson error oscillations
DEFF Research Database (Denmark)
Britz, Dieter; Østerby, Ole; Strutwolf, J.
2003-01-01
The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one...
Electromagnetic Radiation Originating from Unstable Electron Oscillations
DEFF Research Database (Denmark)
Juul Rasmussen, Jens; Pécseli, Hans
1975-01-01
Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function.......Electromagnetic oscillations in the range 300 – 700 MHz were observed from an unmagnetized argon discharge with an unstable electron velocity distribution function....
Multipole expansion method for supernova neutrino oscillations
Energy Technology Data Exchange (ETDEWEB)
Duan, Huaiyu; Shalgar, Shashank, E-mail: duan@unm.edu, E-mail: shashankshalgar@unm.edu [Department of Physics and Astronomy, University of New Mexico, Albuquerque, NM 87131 (United States)
2014-10-01
We demonstrate a multipole expansion method to calculate collective neutrino oscillations in supernovae using the neutrino bulb model. We show that it is much more efficient to solve multi-angle neutrino oscillations in multipole basis than in angle basis. The multipole expansion method also provides interesting insights into multi-angle calculations that were accomplished previously in angle basis.
Modeling diauxic glycolytic oscillations in yeast
DEFF Research Database (Denmark)
Hald, Bjørn Olav; Sørensen, Preben Graae
2010-01-01
Glycolytic oscillations in a stirred suspension of starved yeast cells is an excellent model system for studying the dynamics of metabolic switching in living systems. In an open-flow system the oscillations can be maintained indefinitely at a constant operating point where they can be characteri...
Autonomous Duffing-Holmes Type Chaotic Oscillator
DEFF Research Database (Denmark)
Tamaševičius, A.; Bumelienė, S.; Kirvaitis, R.
2009-01-01
We have designed and built a novel Duffing type autonomous 3rd-order chaotic oscillator. In comparison with the common non-autonomous DuffingHolmes type oscillator the autonomous circuit has an internal positive feedback loop instead of an external periodic drive source. In addition...
Chaos in nonlinear oscillations controlling and synchronization
Lakshamanan, M
1996-01-01
This book deals with the bifurcation and chaotic aspects of damped and driven nonlinear oscillators. The analytical and numerical aspects of the chaotic dynamics of these oscillators are covered, together with appropriate experimental studies using nonlinear electronic circuits. Recent exciting developments in chaos research are also discussed, such as the control and synchronization of chaos and possible technological applications.
Autoresonance versus localization in weakly coupled oscillators
Kovaleva, Agnessa; Manevitch, Leonid I.
2016-04-01
We study formation of autoresonance (AR) in a two-degree of freedom oscillator array including a nonlinear (Duffing) oscillator (the actuator) weakly coupled to a linear attachment. Two classes of systems are studied. In the first class of systems, a periodic force with constant (resonance) frequency is applied to a nonlinear oscillator (actuator) with slowly time-decreasing stiffness. In the systems of the second class a nonlinear time-invariant oscillator is subjected to an excitation with slowly increasing frequency. In both cases, the attached linear oscillator and linear coupling are time-invariant, and the system is initially engaged in resonance. This paper demonstrates that in the systems of the first type AR in the nonlinear actuator entails oscillations with growing amplitudes in the linear attachment while in the system of the second type energy transfer from the nonlinear actuator is insufficient to excite high-energy oscillations of the attachment. It is also shown that a slow change of stiffness may enhance the response of the actuator and make it sufficient to support oscillations with growing energy in the attachment even beyond the linear resonance. Explicit asymptotic approximations of the solutions are obtained. Close proximity of the derived approximations to exact (numerical) results is demonstrated.
In plane oscillation of a bifilar pendulum
Hinrichsen, Peter F.
2016-11-01
The line tensions, the horizontal and vertical accelerations as well as the period of large angle oscillations parallel to the plane of a bifilar suspension are presented and have been experimentally investigated using strain gauges and a smart phone. This system has a number of advantages over the simple pendulum for studying large angle oscillations, and for measuring the acceleration due to gravity.
Experiments with elasto-plastic oscillator
DEFF Research Database (Denmark)
Randrup-thomsen, Søren; Ditlevsen, Ove Dalager
1996-01-01
Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...
Experiments with elasto-plastic oscillator
DEFF Research Database (Denmark)
Randrup-Thomsen, S.; Ditlevsen, Ove Dalager
1999-01-01
Plastic displacements of a Gaussian white noise excited three degrees of freedom non-ideal elasto-plastic oscillator are measured in laboratory experiments and the plastic displacements are compared to computer simulated results for the corresponding ideal elasto-plastic oscillator. The comparative...
Quantum noise-induced chaotic oscillations
Bag, Bidhan Chandra; Ray, Deb Shankar
1999-01-01
We examine the weak quantum noise limit of Wigner equation for phase space distribution functions. It has been shown that the leading order quantum noise described in terms of an auxiliary Hamiltonian manifests itself as an additional fluctuational degree of freedom which may induce chaotic and regular oscillations in a nonlinear oscillator.
Quantum noise-induced chaotic oscillations
Bag, B C; Bag, Bidhan Chandra; Ray, Deb Shankar
1999-01-01
We examine the weak quantum noise limit of Wigner equation for phase space distribution functions. It has been shown that the leading order quantum noise described in terms of an auxilliary Hamiltonian manifests itself as an additional fluctuational degree of freedom which may induce chaotic and regular oscillations in a nonlinear oscillator.
Small X-Band Oscillator Antennas
Lee, Richard Q.; Miranda, Felix A.; Clark, Eric B.; Wilt, David M.; Mueller, Carl H.; Kory, Carol L.; Lambert, Kevin M.
2009-01-01
A small, segmented microstrip patch antenna integrated with an X-band feedback oscillator on a high-permittivity substrate has been built and tested. This oscillator antenna is a prototype for demonstrating the feasibility of such devices as compact, low-power-consumption building blocks of advanced, lightweight, phased antenna arrays that would generate steerable beams for communication and remotesensing applications.
Magnetic dipole oscillations and radiation damping
Stump, Daniel R.; Pollack, Gerald L.
1997-01-01
We consider the problem of radiation damping for a magnetic dipole oscillating in a magnetic field. An equation for the radiation reaction torque is derived, and the damping of the oscillations is described. Also discussed are runaway solutions for a rotating magnetic dipole moving under the influence of the reaction torque, with no external torque.
Averaged Behaviour of Nonconservative Coupled Oscillators
Bakri, T.
2007-01-01
In this Thesis we study the dynamics of systems of two and three coupled oscillators by efficiently applying Normal Form theory. The subject of Coupled oscillators plays an important part in dynamical systems. It has a wide range of applications in various fields like physics, biology, economics and
Photonic Cavity Synchronization of Nanomechanical Oscillators
Bagheri, Mahmood; Poot, Menno; Fan, Linran; Marquardt, Florian; Tang, Hong X.
2013-01-01
Synchronization in oscillatory systems is a frequent natural phenomenon and is becoming an important concept in modern physics. Nanomechanical resonators are ideal systems for studying synchronization due to their controllable oscillation properties and engineerable nonlinearities. Here we demonstrate synchronization of two nanomechanical oscillators via a photonic resonator, enabling optomechanical synchronization between mechanically isolated nanomechanical resonators. Optical backaction gi...
A simple approach to nonlinear oscillators
Ren, Zhong-Fu; He, Ji-Huan
2009-10-01
A very simple and effective approach to nonlinear oscillators is suggested. Anyone with basic knowledge of advanced calculus can apply the method to finding approximately the amplitude-frequency relationship of a nonlinear oscillator. Some examples are given to illustrate its extremely simple solution procedure and an acceptable accuracy of the obtained solutions.
Babaie, M.; Staszewski, R.B.
2013-01-01
An oscillator topology demonstrating an improved phase noise performance is proposed in this paper. It exploits the time-variant phase noise model with insights into the phase noise conversion mechanisms. The proposed oscillator is based on enforcing a pseudo-square voltage waveform around the LC ta
Microwave Oscillator Would Have Reduced Phase Noise
Dick, G. John; Saunders, Jon
1991-01-01
Microwave oscillators of proposed new type incorporate suppressed-carrier/negative-feedback feature to reduce phase noise near their carrier frequencies. Concept results in phase noise less than achievable by cryogenically stabilized microwave components or by room-temperature oscillators stabilized by quartz crystals. Implemented in three different versions.
Design of an Oscillator for Satellite Reception
Leong, F.H.E.H.C.
2007-01-01
This thesis presents research on an LC-oscillator for Ku-band (10.7-12.7GHz) satellite reception. The zero-IF receiver architecture, proposed in the joint project involving the University of Twente and NXP Research, requires a 11.7GHz quadrature oscillator that achieves a phase noise of -85dBc/Hz@10
Experimental observation of shear thickening oscillation
DEFF Research Database (Denmark)
Nagahiro, Shin-ichiro; Nakanishi, Hiizu; Mitarai, Namiko
2013-01-01
We report experimental observations of the shear thickening oscillation, i.e. the spontaneous macroscopic oscillation in the shear flow of severe shear thickening fluid. Using a density-matched starch-water mixture, in the cylindrical shear flow of a few centimeters flow width, we observed...
Signal velocity in oscillator arrays
Cantos, C. E.; Veerman, J. J. P.; Hammond, D. K.
2016-09-01
We investigate a system of coupled oscillators on the circle, which arises from a simple model for behavior of large numbers of autonomous vehicles where the acceleration of each vehicle depends on the relative positions and velocities between itself and a set of local neighbors. After describing necessary and sufficient conditions for asymptotic stability, we derive expressions for the phase velocity of propagation of disturbances in velocity through this system. We show that the high frequencies exhibit damping, which implies existence of well-defined signal velocitiesc+ > 0 and c- < 0 such that low frequency disturbances travel through the flock as f+(x - c+t) in the direction of increasing agent numbers and f-(x - c-t) in the other.
Quasi Periodic Oscillations in Blazars
Indian Academy of Sciences (India)
Alok C. Gupta
2014-09-01
Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important clues of the location and nature of the processes of emission mechanism. In the case of radio-quiet AGN, the detected QPOs are very likely to be associated with the accretion disk. But in the case of blazars, it may be associated with jets in the high and outburst states, and in the low-state, it is probably associated with the accretion disk. In this brief review, I summarize the recent QPO detections in blazars. There is one strong evidence of QPO detection in XMM–Newton time series data of narrow line Seyfert 1 galaxy RE J1034+396 about which we will also discuss briefly.
Sympathetic rhythms and cardiovascular oscillations.
Montano, N; Cogliati, C; Dias da Silva, V J; Gnecchi-Ruscone, T; Malliani, A
2001-07-20
Spectral analysis of heart rate and arterial pressure variabilities is a powerful noninvasive tool, which is increasingly used to infer alterations of cardiovascular autonomic regulation in a variety of physiological and pathophysiological conditions, such as hypertension, myocardial infarction and congestive heart failure. A most important methodological issue to properly interpret the results obtained by the spectral analysis of cardiovascular variability signals is represented by the attribution of neurophysiological correlates to these spectral components. In this regard, recent applications of spectral techniques to the evaluation of the oscillatory properties of sympathetic efferent activity in animals, as well as in humans, offer a new approach to a better understanding of the relationship between cardiovascular oscillations and autonomic regulation.
Hydrodynamic stability and stellar oscillations
Indian Academy of Sciences (India)
H M Antia
2011-07-01
Chandrasekhar’s monograph on Hydrodynamic and hydromagnetic stability, published in 1961, is a standard reference on linear stability theory. It gives a detailed account of stability of ﬂuid ﬂow in a variety of circumstances, including convection, stability of Couette ﬂow, Rayleigh–Taylor instability, Kelvin–Helmholtz instability as well as the Jean’s instability for star formation. In most cases he has extended these studies to include effects of rotation and magnetic ﬁeld. In a later paper he has given a variational formulation for equations of non-radial stellar oscillations. This forms the basis for helioseismic inversion techniques as well as extension to include the effect of rotation, magnetic ﬁeld and other large-scale ﬂows using a perturbation treatment.
Oscillating water column structural model
Energy Technology Data Exchange (ETDEWEB)
Copeland, Guild [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Bull, Diana L [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Jepsen, Richard Alan [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Gordon, Margaret Ellen [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2014-09-01
An oscillating water column (OWC) wave energy converter is a structure with an opening to the ocean below the free surface, i.e. a structure with a moonpool. Two structural models for a non-axisymmetric terminator design OWC, the Backward Bent Duct Buoy (BBDB) are discussed in this report. The results of this structural model design study are intended to inform experiments and modeling underway in support of the U.S. Department of Energy (DOE) initiated Reference Model Project (RMP). A detailed design developed by Re Vision Consulting used stiffeners and girders to stabilize the structure against the hydrostatic loads experienced by a BBDB device. Additional support plates were added to this structure to account for loads arising from the mooring line attachment points. A simplified structure was designed in a modular fashion. This simplified design allows easy alterations to the buoyancy chambers and uncomplicated analysis of resulting changes in buoyancy.
Outdoor W-Band Hybrid Photonic Wireless Link Based on an Optical SFP+ Module
DEFF Research Database (Denmark)
Rommel, Simon; Rodríguez Páez, Juan Sebastián; Chorchos, Łukasz
2016-01-01
This letter proposes aW-band hybrid photonic wireless link based on a commercial SFP+ module and experimentally demonstrates its performance. Using a free running laser as local oscillator and heterodyne photonic upconversion, good frequency stability is achieved. Outdoor wireless transmission ov...
Optically envelope detected QAM and QPSK RF modulated signals in hybrid wireless-fiber systems
DEFF Research Database (Denmark)
Tafur Monroy, Idelfonso; Prince, Kamau; Seoane, Jorge;
2009-01-01
from a 1.6 GHz carrier frequency to an IF at 500 MHz, requiring no high frequency local oscillator and mixer at the remote base station. This result proves the feasibility of optical envelope detection for complex modulation formats of RF signals for hybrid wireless-fiber transmission links....
Han, Wenchen; Cheng, Hongyan; Dai, Qionglin; Li, Haihong; Ju, Ping; Yang, Junzhong
2016-10-01
In this work, we investigate the dynamics in a ring of identical Stuart-Landau oscillators with conjugate coupling systematically. We analyze the stability of the amplitude death and find the stability independent of the number of oscillators. When the amplitude death state is unstable, a large number of states such as homogeneous oscillation death, heterogeneous oscillation death, homogeneous oscillation, and wave propagations are found and they may coexist. We also find that all of these states are related to the unstable spatial modes to the amplitude death state.
Atmospheric neutrino oscillations for Earth tomography
Winter, Walter
2016-07-01
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Discontinuous spirals of stable periodic oscillations.
Sack, Achim; Freire, Joana G; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A C
2013-11-27
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.
Discontinuous Spirals of Stable Periodic Oscillations
Sack, Achim; Freire, Joana G.; Lindberg, Erik; Pöschel, Thorsten; Gallas, Jason A. C.
2013-01-01
We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators. PMID:24284508
Atmospheric Neutrino Oscillations for Earth Tomography
Winter, Walter
2015-01-01
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can robustly measure the lower mantle density of the earth with a precision at the level of 4-5 percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Atmospheric neutrino oscillations for Earth tomography
Energy Technology Data Exchange (ETDEWEB)
Winter, Walter, E-mail: walter.winter@desy.de
2016-07-15
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
Water Oscillation in an Open Tube
Directory of Open Access Journals (Sweden)
Doh Hoon Chung
2008-01-01
Full Text Available When an open tube is placed in a tank of water, covered on top, raised, and then uncovered, the water inside the tube will oscillate. The characteristics of the oscillation of the water inside the tube were studied. It was shown that, for large oscillations, the top half-period was longer than the bottom half period due to the increased mass of the water column. For small oscillations, it approached simple harmonic motion, with the square of the period varying with mean length, as predicted by theory. An end correction was also shown to exist, due to the motion of the water outside the bottom of the tube during the oscillation. The end correction was shown to be independent of the mean length of the water column, as predicted.
Multistable phase patterns in finite oscillator networks
Goldstein, Daniel
2014-03-01
Recent experiments on spatially extend arrays of droplets containing Belousov-Zhabotinsky reactants have shown a rich variety of spatio-temporal patterns. Motivated by this experimental set up, we study a simple model of chemical oscillators in the highly nonlinear excitable regime in order to gain insight into the mechanism giving rise to the observed multistable attractors. By allowing intrinsic fluctuations to influence a simple activator inhibitor model, switching between stable attractors is observed. When coupled, these two attractors have different preferred phase synchronizations, leading to complex behavior. We study rings of coupled oscillators and observe a rich array of oscillating patterns. We characterize the different modes of oscillation in the mean-field model and compare those to the oscillations observed in stochastic simulations.
Chemical sensor with oscillating cantilevered probe
Adams, Jesse D
2013-02-05
The invention provides a method of detecting a chemical species with an oscillating cantilevered probe. A cantilevered beam is driven into oscillation with a drive mechanism coupled to the cantilevered beam. A free end of the oscillating cantilevered beam is tapped against a mechanical stop coupled to a base end of the cantilevered beam. An amplitude of the oscillating cantilevered beam is measured with a sense mechanism coupled to the cantilevered beam. A treated portion of the cantilevered beam is exposed to the chemical species, wherein the cantilevered beam bends when exposed to the chemical species. A second amplitude of the oscillating cantilevered beam is measured, and the chemical species is determined based on the measured amplitudes.
Estimating the phase of synchronized oscillators
Revzen, Shai; Guckenheimer, John M.
2008-11-01
The state of a collection of phase-locked oscillators is determined by a single phase variable or cyclic coordinate. This paper presents a computational method, Phaser, for estimating the phase of phase-locked oscillators from limited amounts of multivariate data in the presence of noise and measurement errors. Measurements are assumed to be a collection of multidimensional time series. Each series consists of several cycles of the same or similar systems. The oscillators within each system are not assumed to be identical. Using measurements of the noise covariance for the multivariate input, data from the individual oscillators in the system are combined to reduce the variance of phase estimates for the whole system. The efficacy of the algorithm is demonstrated on experimental and model data from biomechanics of cockroach running and on simulated oscillators with varying levels of noise.
Baryogenesis via Particle-Antiparticle Oscillations
Ipek, Seyda
2016-01-01
CP violation, which is crucial for producing the baryon asymmetry of the Universe, is enhanced in particle-antiparticle oscillations. We study particle-antiparticle oscillations (of a particle with mass O(100 GeV)) with CP violation in the early Universe in the presence of interactions with O(ab-fb) cross-sections. We show that, if baryon-number-violating interactions exist, a baryon asymmetry can be produced via out-of-equilibrium decays of oscillating particles. As a concrete example we study a $U(1)_R$-symmetric, R-parity-violating SUSY model with pseudo-Dirac gauginos, which undergo particle-antiparticle oscillations. Taking bino to be the lightest $U(1)_R$-symmetric particle, and assuming it decays via baryon-number-violating interactions, we show that bino-antibino oscillations can produce the baryon asymmetry of the Universe.
Atmospheric neutrino oscillations for earth tomography
Energy Technology Data Exchange (ETDEWEB)
Winter, Walter
2016-04-05
Modern proposed atmospheric neutrino oscillation experiments, such as PINGU in the Antarctic ice or ORCA in Mediterranean sea water, aim for precision measurements of the oscillation parameters including the ordering of the neutrino masses. They can, however, go far beyond that: Since neutrino oscillations are affected by the coherent forward scattering with matter, neutrinos can provide a new view on the interior of the earth. We show that the proposed atmospheric oscillation experiments can measure the lower mantle density of the earth with a precision at the level of a few percent, including the uncertainties of the oscillation parameters and correlations among different density layers. While the earth's core is, in principle, accessible by the angular resolution, new technology would be required to extract degeneracy-free information.
The quantum measurement approach to particle oscillations
Anastopoulos, C
2010-01-01
The LSND and MiniBoone seeming anomalies in neutrino oscillations are usually attributed to physics beyond the Standard model. It is, however, possible that they may be an artefact of the theoretical treatment of particle oscillations that ignores fine points of quantum measurement theory relevant to the experiments. In this paper, we construct a rigorous measurement-theoretic framework for the description of particle oscillations, employing no assumptions extrinsic to quantum theory. The formalism leads to a non-standard oscillation formula; at low energy it predicts an `anomalous' oscillation wavelength, while at high energy it differs from the standard expression by a factor of 2. The key novelties in the formalism are the treatment of a particle's time of arrival at the detector as a genuine quantum observable, the theoretical precision in the definition of quantum probabilities, and the detailed modeling of the measurement process. The article also contains an extensive critical review of existing theore...
Improved memristor-based relaxation oscillator
Mosad, Ahmed G.
2013-09-01
This paper presents an improved memristor-based relaxation oscillator which offers higher frequency and wider tunning range than the existing reactance-less oscillators. It also has the capability of operating on two positive supplies or alternatively a positive and negative supply. Furthermore, it has the advantage that it can be fully integrated on-chip providing an area-efficient solution. On the other hand, The oscillation concept is discussed then a complete mathematical analysis of the proposed oscillator is introduced. Furthermore, the power consumption of the new relaxation circuit is discussed and validated by the PSPICE circuit simulations showing an excellent agreement. MATLAB results are also introduced to demonstrate the resistance range and the corresponding frequency range which can be obtained from the proposed relaxation oscillator. © 2013 Elsevier Ltd.
Global dynamics of a stochastic neuronal oscillator
Yamanobe, Takanobu
2013-11-01
Nonlinear oscillators have been used to model neurons that fire periodically in the absence of input. These oscillators, which are called neuronal oscillators, share some common response structures with other biological oscillations such as cardiac cells. In this study, we analyze the dependence of the global dynamics of an impulse-driven stochastic neuronal oscillator on the relaxation rate to the limit cycle, the strength of the intrinsic noise, and the impulsive input parameters. To do this, we use a Markov operator that both reflects the density evolution of the oscillator and is an extension of the phase transition curve, which describes the phase shift due to a single isolated impulse. Previously, we derived the Markov operator for the finite relaxation rate that describes the dynamics of the entire phase plane. Here, we construct a Markov operator for the infinite relaxation rate that describes the stochastic dynamics restricted to the limit cycle. In both cases, the response of the stochastic neuronal oscillator to time-varying impulses is described by a product of Markov operators. Furthermore, we calculate the number of spikes between two consecutive impulses to relate the dynamics of the oscillator to the number of spikes per unit time and the interspike interval density. Specifically, we analyze the dynamics of the number of spikes per unit time based on the properties of the Markov operators. Each Markov operator can be decomposed into stationary and transient components based on the properties of the eigenvalues and eigenfunctions. This allows us to evaluate the difference in the number of spikes per unit time between the stationary and transient responses of the oscillator, which we show to be based on the dependence of the oscillator on past activity. Our analysis shows how the duration of the past neuronal activity depends on the relaxation rate, the noise strength, and the impulsive input parameters.
OSCILLATION-DRIVEN MAGNETOSPHERIC ACTIVITY IN PULSARS
Energy Technology Data Exchange (ETDEWEB)
Lin, Meng-Xiang; Xu, Ren-Xin; Zhang, Bing, E-mail: linmx97@gmail.com, E-mail: r.x.xu@pku.edu.cn, E-mail: zhang@physics.unlv.edu [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China)
2015-02-01
We study the magnetospheric activity in the polar cap region of pulsars under stellar oscillations. The toroidal oscillation of the star propagates into the magnetosphere, which provides additional voltage due to unipolar induction, changes Goldreich-Julian charge density from the traditional value due to rotation, and hence influences particle acceleration. We present a general solution of the effect of oscillations within the framework of the inner vacuum gap model and consider three different inner gap modes controlled by curvature radiation, inverse Compton scattering, and two-photon annihilation, respectively. With different pulsar parameters and oscillation amplitudes, one of three modes would play a dominant role in defining the gap properties. When the amplitude of oscillation exceeds a critical value, mode changing occurs. Oscillations also lead to a change of the size of the polar cap. As applications, we show the inner gap properties under oscillations in both normal pulsars and anomalous X-ray pulsars/soft gamma-ray repeaters (AXPs/SGRs). We interpret the onset of radio emission after glitches/flares in AXPs/SGRs as due to oscillation-driven magnetic activities in these objects, within the framework of both the magnetar model and the solid quark star model. Within the magnetar model, radio activation may be caused by the enlargement of the effective polar cap angle and the radio emission beam due to oscillation, whereas within the solid quark star angle, it may be caused by activation of the pulsar inner gap from below the radio emission death line due to an oscillation-induced voltage enhancement. The model can also explain the glitch-induced radio profile change observed in PSR J1119–6127.
Energy Technology Data Exchange (ETDEWEB)
Gaemperli, Oliver [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); University Hospital Zurich, Nuclear Cardiology, Cardiovascular Center, Zurich (Switzerland); Kaufmann, Philipp A. [University Hospital Zurich, Cardiac Imaging, Zurich (Switzerland); Alkadhi, Hatem [University Hospital Zurich, Institute of Diagnostic and Interventional Radiology, Zurich (Switzerland)
2014-05-15
Hybrid cardiac single photon emission computed tomography (SPECT)/CT imaging allows combined assessment of anatomical and functional aspects of cardiac disease. In coronary artery disease (CAD), hybrid SPECT/CT imaging allows detection of coronary artery stenosis and myocardial perfusion abnormalities. The clinical value of hybrid imaging has been documented in several subsets of patients. In selected groups of patients, hybrid imaging improves the diagnostic accuracy to detect CAD compared to the single imaging techniques. Additionally, this approach facilitates functional interrogation of coronary stenoses and guidance with regard to revascularization procedures. Moreover, the anatomical information obtained from CT coronary angiography or coronary artery calcium scores (CACS) adds prognostic information over perfusion data from SPECT. The use of cardiac hybrid imaging has been favoured by the dissemination of dedicated hybrid systems and the release of dedicated image fusion software, which allow simple patient throughput for hybrid SPECT/CT studies. Further technological improvements such as more efficient detector technology to allow for low-radiation protocols, ultra-fast image acquisition and improved low-noise image reconstruction algorithms will be instrumental to further promote hybrid SPECT/CT in research and clinical practice. (orig.)
Hybrid intelligent engineering systems
Jain, L C; Adelaide, Australia University of
1997-01-01
This book on hybrid intelligent engineering systems is unique, in the sense that it presents the integration of expert systems, neural networks, fuzzy systems, genetic algorithms, and chaos engineering. It shows that these new techniques enhance the capabilities of one another. A number of hybrid systems for solving engineering problems are presented.
DEFF Research Database (Denmark)
Jamison, Andrew; Christensen, Steen Hyldgaard; Botin, Lars
contexts, or sites, for mixing scientific knowledge and technical skills from different fields and social domains into new combinations, thus fostering what the authors term a “hybrid imagination”. Such a hybrid imagination is especially important today, as a way to counter the competitive and commercial...
Collins, P.J.
2005-01-01
In this paper, we present a general framework for describing and studying hybrid systems. We represent the trajectories of the system as functions on a hybrid time domain, and the system itself by its trajectory space, which is the set of all possible trajectories. The trajectory space is given a na
DEFF Research Database (Denmark)
Olderog, Ernst-Rüdiger; Ravn, Anders Peter
2007-01-01
An introduction to three papers in a special issue on Hybrid Systems. These paper were first presented at an IFIP WG 2.2 meeting in Skagen 2005.......An introduction to three papers in a special issue on Hybrid Systems. These paper were first presented at an IFIP WG 2.2 meeting in Skagen 2005....
Energy Technology Data Exchange (ETDEWEB)
Moir, R.W.
1980-09-09
The rationale for hybrid fusion-fission reactors is the production of fissile fuel for fission reactors. A new class of reactor, the fission-suppressed hybrid promises unusually good safety features as well as the ability to support 25 light-water reactors of the same nuclear power rating, or even more high-conversion-ratio reactors such as the heavy-water type. One 4000-MW nuclear hybrid can produce 7200 kg of /sup 233/U per year. To obtain good economics, injector efficiency times plasma gain (eta/sub i/Q) should be greater than 2, the wall load should be greater than 1 MW.m/sup -2/, and the hybrid should cost less than 6 times the cost of a light-water reactor. Introduction rates for the fission-suppressed hybrid are usually rapid.
Hybrid propulsion technology program
1990-01-01
Technology was identified which will enable application of hybrid propulsion to manned and unmanned space launch vehicles. Two design concepts are proposed. The first is a hybrid propulsion system using the classical method of regression (classical hybrid) resulting from the flow of oxidizer across a fuel grain surface. The second system uses a self-sustaining gas generator (gas generator hybrid) to produce a fuel rich exhaust that was mixed with oxidizer in a separate combustor. Both systems offer cost and reliability improvement over the existing solid rocket booster and proposed liquid boosters. The designs were evaluated using life cycle cost and reliability. The program consisted of: (1) identification and evaluation of candidate oxidizers and fuels; (2) preliminary evaluation of booster design concepts; (3) preparation of a detailed point design including life cycle costs and reliability analyses; (4) identification of those hybrid specific technologies needing improvement; and (5) preperation of a technology acquisition plan and large scale demonstration plan.
Intraseasonal oscillations of stratospheric ozone above Switzerland
Studer, Simone; Hocke, Klemens; Kämpfer, Niklaus
2012-01-01
GROMOS, the ground-based millimeter-wave ozone spectrometer, continuously measures the stratospheric ozone profile between the altitudes of 20 and 65 km above Bern (46°57‧N, 7°27‧E) since November 1994. Characteristics of intraseasonal oscillations of stratospheric ozone are derived from the long-term data set. Spectral analysis gives evidence for a dominant oscillation period of about 20 days in the lower and middle stratosphere during winter time. A strong 20-day wave is also found in collocated geopotential height measurements of the microwave limb sounder onboard the Aura satellite (Aura/MLS) confirming the ground-based observations of GROMOS and underlining the link between ozone and dynamics. Remarkably, the ozone series of GROMOS show an interannual variability of the strength of intraseasonal oscillations of stratospheric ozone. The interannual variability of ozone fluctuations is possibly due to influences of planetary wave forcing and the quasi-biennial oscillation (QBO) on the meridional Brewer-Dobson circulation of the middle atmosphere. In detail, time series of the mean amplitude of ozone fluctuations with periods ranging from 10 to 60 days are derived at fixed pressure levels. The mean amplitude series are regarded as a measure of the strength of intraseasonal oscillations of stratospheric ozone above Bern. After deseasonalizing the mean amplitude series, we find QBO-like amplitude modulations of the intraseasonal oscillations of ozone. The amplitudes of the intraseasonal oscillations are enhanced by a factor of 2 in 1997, 2001, 2003, and 2005. QBO-like variations of intraseasonal oscillations are also present in wind, temperature and other parameters above Bern as indicated by meteorological reanalyses of the European Centre for Medium-range Weather Forecasts (ECMWF). Further, intercomparisons of interannual variability of intraseasonal tropospheric and stratospheric oscillations are performed where the NAO index (North-Atlantic oscillation
Harmonic oscillation in a spatially finite array waveguide.
Gordon, R
2004-12-01
A waveguide array is presented that behaves as an oscillator, showing periodic image reconstruction, focusing, and transverse wave-packet oscillation. The oscillator has a finite width, which removes the need for premature truncation. The array waveguide oscillator shows properties analogous to those of a pedagogically important one-dimensional quantum harmonic oscillator, which are fundamentally different from previously demonstrated oscillations in Wannier-Stark waveguide arrays. Calculations of the entire array waveguide oscillator are presented that quantify higher-order corrections to the coupled-mode approach. These results can be extended to waveguide oscillators in other systems, such as electrons in superlattices.
Multivariate Time Series Decomposition into Oscillation Components.
Matsuda, Takeru; Komaki, Fumiyasu
2017-08-01
Many time series are considered to be a superposition of several oscillation components. We have proposed a method for decomposing univariate time series into oscillation components and estimating their phases (Matsuda & Komaki, 2017 ). In this study, we extend that method to multivariate time series. We assume that several oscillators underlie the given multivariate time series and that each variable corresponds to a superposition of the projections of the oscillators. Thus, the oscillators superpose on each variable with amplitude and phase modulation. Based on this idea, we develop gaussian linear state-space models and use them to decompose the given multivariate time series. The model parameters are estimated from data using the empirical Bayes method, and the number of oscillators is determined using the Akaike information criterion. Therefore, the proposed method extracts underlying oscillators in a data-driven manner and enables investigation of phase dynamics in a given multivariate time series. Numerical results show the effectiveness of the proposed method. From monthly mean north-south sunspot number data, the proposed method reveals an interesting phase relationship.
Pole movement in electronic and optoelectronic oscillators
Chatterjee, S.; Pal, S.; Biswas, B. N.
2013-12-01
An RLC circuit with poles on the left half of the complex frequency plane is capable of executing transient oscillations. During this period, energy conversion from potential to kinetic and from kinetic to potential continuously goes on, until the stored energy is lost in dissipation through the resistance. On the other hand, in an electronic or opto-electronic oscillator with an embedded RLC circuit, the poles are forcibly placed on the right-half plane (RHP) and as far as practicable away from the imaginary axis in order to help the growth of oscillation as quickly as possible. And ultimately, it is imagined that, like the case of an ideal linear harmonic oscillator, the poles are frozen on the imaginary axis so that the oscillation neither grows nor decays. The authors feel that this act of holding the poles right on the imaginary axis is a theoretical conjecture in a soft or hard self-excited oscillator. In this article, a detailed discussion on pole movement in an electronic and opto-electronic oscillator is carried out from the basic concept. A new analytical method for estimating the time-dependent part of the pole is introduced here.
Oscillations in a sunspot with light bridges
Yuan, Ding; Huang, Zhenghua; Li, Bo; Su, Jiangtao; Yan, Yihua; Tan, Baolin
2014-01-01
Solar Optical Telescope onboard Hinode observed a sunspot (AR 11836) with two light bridges (LBs) on 31 Aug 2013. We analysed a 2-hour \\ion{Ca}{2} H emission intensity data set and detected strong 5-min oscillation power on both LBs and in the inner penumbra. The time-distance plot reveals that 5-min oscillation phase does not vary significantly along the thin bridge, indicating that the oscillations are likely to originate from the underneath. The slit taken along the central axis of the wide light bridge exhibits a standing wave feature. However, at the centre of the wide bridge, the 5-min oscillation power is found to be stronger than at its sides. Moreover, the time-distance plot across the wide bridge exhibits a herringbone pattern that indicates a counter-stream of two running waves originated at the bridge sides. Thus, the 5-min oscillations on the wide bridge also resemble the properties of running penumbral waves. The 5-min oscillations are suppressed in the umbra, while the 3-min oscillations occupy...