WorldWideScience

Sample records for sustained self-perpetuating oscillations

  1. Self-perpetuating development of encoding biases.

    Science.gov (United States)

    Lewicki, P; Hill, T; Sasaki, I

    1989-12-01

    The process of encoding new information involves the imposition of preexisting interpretive categories on newly encountered stimuli, even if the categories do not match perfectly those stimuli. We hypothesized that such encoding of stimuli as supportive of preexisting encoding dispositions may become a source of a perceiver's subjective experiences that support these dispositions. Through this nonconsciously operating mechanism, encoding rules may gradually develop in a self-perpetuating manner, even in the absence of any objectively supportive evidence. Results demonstrated this self-perpetuating process in three studies involving different stimulus materials and experimental tasks (matrix-scanning paradigm and two "intuitive judgment" tasks). The self-perpetuating development of encoding biases is discussed as one of the elementary mechanisms involved in the development of interpretive categories and other individually differentiated cognitive dispositions.

  2. Self-perpetuating development of encoding biases in person perception.

    Science.gov (United States)

    Hill, T; Lewicki, P; Czyzewska, M; Boss, A

    1989-09-01

    It was hypothesized that encoding (interpretive) biases may develop in a self-perpetuating manner through biased, self-supportive encoding (even in the absence of any objectively supportive evidence). This process was investigated in 3 experiments with different stimulus materials (matrices of digits, silhouettes of persons, descriptions of personal problems). In the learning phase of each study, Ss nonconsciously acquired some encoding bias. In the testing phase, Ss' encoding of new material was predictably biased, and, consistent with the self-perpetuation hypothesis, the strength of the bias gradually increased over the segments of the material, even though the material did not contain any evidence supportive of the bias. Given the ambiguity of many (particularly social) stimuli, the self-perpetuation process may play a ubiquitous role in the development of interpretive categories and other individually differentiated cognitive dispositions.

  3. Sustained oscillations in living cells

    Science.gov (United States)

    Danø, Sune; Sørensen, Preben Graae; Hynne, Finn

    1999-11-01

    Glycolytic oscillations in yeast have been studied for many years simply by adding a glucose pulse to a suspension of cells and measuring the resulting transient oscillations of NADH. Here we show, using a suspension of yeast cells, that living cells can be kept in a well defined oscillating state indefinitely when starved cells, glucose and cyanide are pumped into a cuvette with outflow of surplus liquid. Our results show that the transitions between stationary and oscillatory behaviour are uniquely described mathematically by the Hopf bifurcation. This result characterizes the dynamical properties close to the transition point. Our perturbation experiments show that the cells remain strongly coupled very close to the transition. Therefore, the transition takes place in each of the cells and is not a desynchronization phenomenon. With these two observations, a study of the kinetic details of glycolysis, as it actually takes place in a living cell, is possible using experiments designed in the framework of nonlinear dynamics. Acetaldehyde is known to synchronize the oscillations. Our results show that glucose is another messenger substance, as long as the glucose transporter is not saturated.

  4. Sustained oscillations for density dependent Markov processes.

    Science.gov (United States)

    Baxendale, Peter H; Greenwood, Priscilla E

    2011-09-01

    Simulations of models of epidemics, biochemical systems, and other bio-systems show that when deterministic models yield damped oscillations, stochastic counterparts show sustained oscillations at an amplitude well above the expected noise level. A characterization of damped oscillations in terms of the local linear structure of the associated dynamics is well known, but in general there remains the problem of identifying the stochastic process which is observed in stochastic simulations. Here we show that in a general limiting sense the stochastic path describes a circular motion modulated by a slowly varying Ornstein-Uhlenbeck process. Numerical examples are shown for the Volterra predator-prey model, Sel'kov's model for glycolysis, and a damped linear oscillator. © Springer-Verlag 2010

  5. Sustained glycolytic oscillations in individual isolated yeast cells.

    Science.gov (United States)

    Gustavsson, Anna-Karin; van Niekerk, David D; Adiels, Caroline B; du Preez, Franco B; Goksör, Mattias; Snoep, Jacky L

    2012-08-01

    Yeast glycolytic oscillations have been studied since the 1950s in cell-free extracts and intact cells. For intact cells, sustained oscillations have so far only been observed at the population level, i.e. for synchronized cultures at high biomass concentrations. Using optical tweezers to position yeast cells in a microfluidic chamber, we were able to observe sustained oscillations in individual isolated cells. Using a detailed kinetic model for the cellular reactions, we simulated the heterogeneity in the response of the individual cells, assuming small differences in a single internal parameter. This is the first time that sustained limit-cycle oscillations have been demonstrated in isolated yeast cells. The mathematical model described here has been submitted to the JWS Online Cellular Systems Modelling Database and can be accessed at http://jjj.biochem.sun.ac.za/database/gustavsson/index.html free of charge. © 2012 The Authors Journal compilation © 2012 FEBS.

  6. Effects of electromagnetic forcing on self-sustained jet oscillations

    NARCIS (Netherlands)

    Kalter, R.; Tummers, M.J.; Kenjeres, S.; Righolt, B.W.; Kleijn, C.R.

    2014-01-01

    The influence of electromagnetic forcing on self-sustained oscillations of a jet issuing from a submerged nozzle into a thin vertical cavity (width W much larger than thickness T) has been studied using particle image velocimetry. A permanent Lorentz force is produced by applying an electrical

  7. Modelling vertical human walking forces using self-sustained oscillator

    Science.gov (United States)

    Kumar, Prakash; Kumar, Anil; Racic, Vitomir; Erlicher, Silvano

    2018-01-01

    This paper proposes a model of a self-sustained oscillator which can generate reliably the vertical contact force between the feet of a healthy pedestrian and the supporting flat rigid surface. The model is motivated by the self-sustained nature of the walking process, i.e. a pedestrian generates the required inner energy to sustain its repetitive body motion. The derived model is a fusion of the well-known Rayleigh, Van der Pol and Duffing oscillators. Some additional nonlinear terms are added to produce both the odd and even harmonics observed in the experimentally measured force data. The model parameters were derived from force records due to twelve pedestrians walking on an instrumented treadmill at ten speeds using a linear least square technique. The stability analysis was performed using the energy balance method and perturbation method. The results obtained from the model show a good agreement with the experimental results.

  8. Sustainable limitation of high-frequency oscillations of elevator cabin

    Science.gov (United States)

    Kaytukov, Batraz

    2017-10-01

    In this paper, a problem of sustainable limitation of vertical high-frequency oscillations of elevator cabin in buildings with various number of storeys is considered. To solve this problem, dynamic model of the elevator movement was developed. In the course of analytical and experimental studies, the main cause for emergence of undesirable high-frequency oscillations of a cabin was defined. The amplification factor which is the function of λ and length of cable was determined. The λ parameter is variable, and length of the cable changes depending on length passed by the cabin and is an amplification factor argument. For sustainable limitation of oscillations, use of dynamic dumper of lever type is proposed. Adjustment of the dumper natural vibration frequency in such a way that it is equal to the excitation frequency allows limiting of oscillations of the cabin and the elevator machine to reasonable value irrespective to position of a moving cabin in the shaft. Using dependences and plots which were obtained in the course of scientific analysis and experimental studies, reasonability of dumper application for sustainable limitation of high-frequency influence of the elevator machine on the base and obtaining of solutions of inertial forces equilibration problem was proved.

  9. Self-Sustaining Dynamical Nuclear Polarization Oscillations in Quantum Dots

    DEFF Research Database (Denmark)

    Rudner, Mark Spencer; Levitov, Leonid

    2013-01-01

    a minimal albeit realistic model of coupled electron and nuclear spin dynamics which supports self-sustained oscillations. Our mechanism relies on a nuclear spin analog of the tunneling magnetoresistance phenomenon (spin-dependent tunneling rates in the presence of an inhomogeneous Overhauser field......Early experiments on spin-blockaded double quantum dots revealed robust, large-amplitude current oscillations in the presence of a static (dc) source-drain bias. Despite experimental evidence implicating dynamical nuclear polarization, the mechanism has remained a mystery. Here we introduce......) and nuclear spin diffusion, which governs dynamics of the spatial profile of nuclear polarization. The proposed framework naturally explains the differences in phenomenology between vertical and lateral quantum dot structures as well as the extremely long oscillation periods....

  10. Screw-dislocation-driven growth of ZnO nanotubes seeded by self-perpetuating spirals during hydrothermal processing

    Science.gov (United States)

    Kim, Sojin; Kang, Hyon Chol

    2016-09-01

    We report the effects of precursor concentration on the characteristics of ZnO nanostructures during hydrothermal processing. Self-perpetuating surface spirals are fabricated at concentrations of 0.25 and 0.5 M, with samples grown at concentrations of 0.05 and 0.125 M exhibiting ZnO nanorods. This can be explained by a change in the growth mode from an initial columnar growth to a screw-dislocation-driven growth with decreased supersaturation. The screw dislocations nucleate at the V-shaped valleys of the columnar boundaries during the intermediate stage. We demonstrate that continuous screw-dislocation-driven growth leads to the formation of ZnO nanotubes having Burger's vectors of 1.45 nm.

  11. Mechanism behind self-sustained oscillations in direct current glow discharges and in dusty plasmas

    CERN Document Server

    Cho, Sung Nae

    2013-01-01

    An alternative explanation to the mechanism behind self-sustained oscillations of ions in direct current (DC) glow discharges is provided. Such description is distinguished from the one provided by fluid models, where oscillations are attributed to positive feedback mechanism associated with photoionization of particles and photoemission of electrons from the cathode. Here, oscillations arise as consequence of interaction between an ion and surface charges induced by it at the bounding electrodes. Such mechanism provides an elegant explanation to why self-sustained oscillations occur only in the negative resistance region of the voltage-current characteristic curve in DC glow discharges. It is found that oscillation frequencies increase with ion's surface charge density, but at the rate which is significantly slower than it does with electric field. The presented mechanism also describes the self-sustained oscillations of ions in dusty plasmas, demonstrating that oscillations in dusty plasmas and DC glow disc...

  12. Duffing revisited: Phase-shift control and internal resonance in self-sustained oscillators

    CERN Document Server

    Arroyo, Sebastián I

    2014-01-01

    We address two aspects of the dynamics of the forced Duffing oscillator which are relevant to the technology of micromechanical devices and, at the same time, disclose new effects of nonlinearities on oscillating systems. First, we study the stability of periodic motion when the phase shift between the external force and the oscillation is controlled -contrary to the standard case, where the control parameter is the frequency of the force. Phase-shift control is the operational configuration under which self-sustained oscillators -and, in particular, micromechanical oscillators- provide a frequency reference useful for time keeping. We show that, contrary to the standard forced Duffing oscillator, under phase-shift control oscillations are stable over the whole resonance curve. Second, we analyze a model for the internal resonance between the main Duffing oscillation mode and a higher-harmonic mode of a vibrating solid bar clamped at its two ends. We focus on the stabilization of the oscillation frequency whe...

  13. Control of forced self-sustained oscillations via a backward time controller

    Energy Technology Data Exchange (ETDEWEB)

    Pyragas, K. [Semiconductor Physics Institute, LT-01108 Vilnius (Lithuania)]. E-mail: pyragas@pfi.lt; Pyragiene, T. [Semiconductor Physics Institute, LT-01108 Vilnius (Lithuania); Tamasevicius, A. [Semiconductor Physics Institute, LT-01108 Vilnius (Lithuania); Mykolaitis, G. [Semiconductor Physics Institute, LT-01108 Vilnius (Lithuania)

    2006-02-13

    A weakly non-linear self-sustained oscillator can be synchronized by an external force only in a certain domain of parameters. We exploit unstable periodic orbits and extend this domain via a small control perturbation. The controller is constructed as a backward time replica of the original oscillator that has the same periodic orbits but with the opposite stability properties. The control is achieved by synchronizing the original oscillator with its backward time replica. We demonstrate these ideas both theoretically and experimentally.

  14. Self-sustained carbon monoxide oxidation oscillations on size-selected platinum nanoparticles at atmospheric pressure

    DEFF Research Database (Denmark)

    Jensen, Robert; Andersen, Thomas; Nierhoff, Anders Ulrik Fregerslev

    2013-01-01

    High-quality mass spectrometry data of the oscillatory behavior of CO oxidation on SiO2 supported Pt-nanoparticles at atmospheric pressure have been acquired as a function of pressure, coverage, gas composition and nanoparticle size. The oscillations are self-sustained for several days at constan...

  15. Dissociable Decoding of Spatial Attention and Working Memory from EEG Oscillations and Sustained Potentials.

    Science.gov (United States)

    Bae, Gi-Yeul; Luck, Steven J

    2017-11-22

    In human scalp EEG recordings, both sustained potentials and alpha-band oscillations are present during the delay period of working memory tasks and may therefore reflect the representation of information in working memory. However, these signals may instead reflect support mechanisms rather than the actual contents of memory. In particular, alpha-band oscillations have been tightly tied to spatial attention and may not reflect location-independent memory representations per se. To determine how sustained and oscillating EEG signals are related to attention and working memory, we attempted to decode which of 16 orientations was being held in working memory by human observers (both women and men). We found that sustained EEG activity could be used to decode the remembered orientation of a stimulus, even when the orientation of the stimulus varied independently of its location. Alpha-band oscillations also carried clear information about the location of the stimulus, but they provided little or no information about orientation independently of location. Thus, sustained potentials contain information about the object properties being maintained in working memory, consistent with previous evidence of a tight link between these potentials and working memory capacity. In contrast, alpha-band oscillations primarily carry location information, consistent with their link to spatial attention.Significance StatementWorking memory plays a key role in cognition, and working memory is impaired in several neurological and psychiatric disorders. Previous research has suggested that human scalp EEG recordings contain signals that reflect the neural representation of information in working memory. However, to conclude that a neural signal actually represents the object being remembered, it is necessary to show that the signal contains fine-grained information about that object. Here, we show that sustained voltages in human EEG recordings contain fine-grained information about the

  16. Self-sustained hysteretic motional oscillations of a single atom pumped by a laser standing wave

    CERN Document Server

    Kaplan, A E

    1999-01-01

    Summary form only given. Self-sustained oscillations/oscillators (SSO), man-made or naturally occurring, are some of the most universal phenomena. The common feature of all SSO is the so called positive feedback, which overcomes the damping by properly controlling the energy supply (pumping) from the outside source during the cycle of oscillations. Usually, the zero steady-state point of the system is unstable, and the oscillations grow up till they reach a stable limit cycle. The common quality of the resulting SSO is their well defined amplitude (the so called classical squeezing) at the expense of undetermined phase of oscillations. All the "mechanical motion" SSO known so far, were based on macro- systems, while it would be of great importance to develop a microscopic SS-oscillator based on a single particle (atom or ion), which would enable us to control the SSO mode from classical to quantum limits. The effect proposed is based on the interaction of a standing laser wave with an atom moving in along the...

  17. Phase-noise reduction in surface wave oscillators by using nonlinear sustaining amplifiers.

    Science.gov (United States)

    Avramov, Ivan D

    2006-04-01

    Nonlinear sustaining amplifier operation has been investigated and applied to high-power negative resistance oscillators (NRO), using single-port surface transverse wave (STW) resonators, and single-transistor sustaining amplifiers for feedback-loop STW oscillators (FLSO) stabilized with two-port STW devices. In all cases, self-limiting, silicon (Si)-bipolar sustaining amplifiers that operate in the highly nonlinear AB-, B-, or C-class modes are implemented. Phase-noise reduction is based on the assumption that a sustaining amplifier, operating in one of these modes, uses current limiting and remains cut off over a significant portion of the wave period. Therefore, it does not generate 1/f noise over the cut-off portion of the radio frequency (RF) cycle, and this reduces the close-in oscillator phase noise significantly. The proposed method has been found to provide phase-noise levels in the -111 to -119 dBc/Hz range at 1 KHz carrier offset in 915 MHz C-class power NRO and FLSO generating up to 23 dBm of RF-power at RF versus dc (RF/dc) efficiencies exceeding 40%. C-class amplifier design techniques are used for adequate matching and high RF/dc efficiency.

  18. The coffee-drop phenomenon and its time fluctuations: Self-sustained oscillations in colloidal liquids

    Science.gov (United States)

    Yakhno, T. A.; Yakhno, V. G.

    2017-03-01

    The instant coffee model has been taken to study self-sustained oscillations in liquid dispersive media using dynamic self-organization processes in drying droplets that stay sessile on a solid wetted substrate. The width of the formed ring and the dynamics of mechanical properties of the drying sediment and the way they fluctuated over 11 h of the experiment have been measured. Analysis has shown a high degree of correlation between these indicators. This dynamics reflects processes that develop in the examined liquid medium. The possible mechanism of self-sustained oscillations, which is related to the aggregation-disaggregation of the colloidal phase and fluctuations of the interphase tension, has been discussed. The practical significance of this work is that fluctuation processes in liquid dispersive media need to be taken into account as a natural source of systematic measurement error.

  19. Experimental evaluation of anti-sound approach in damping self-sustained thermoacoustics oscillations

    Science.gov (United States)

    Li, Xinyan; Zhao, Dan; Li, Junwei; Xu, Yousheng

    2013-11-01

    Self-sustained thermoacoustics oscillations most often arise due to the coupling between unsteady heat release and acoustic waves. The large-amplitude oscillations are wanted in thermoacoustic engine systems. However, they are undesirable in many other systems such as aero-engine afterburners, rocket motors, ramjets, and gas turbines, since the oscillations may become so intense that they cause structural damage and costly mission failure. In this work, we experimentally investigate the "anti-sound" approach in damping Rijke-type thermoacoustic oscillations by actuating a monopole-like sound source. For this, four different least-mean-square (LMS) algorithms are used to determine the "anti-sound" signal to drive the actuator. Comparison is then made. It is found that the LMS-based "anti-sound" approach is able to minimize the thermoacoustic oscillations, even when the operating conditions are slightly changed. Sound pressure level is reduced by 45 dB. Finally, a numerical model is developed to gain insights on the interaction between the monopole sound source and the system. Unsteady heat release from the flame is assumed to be caused by its surface variations resulting from the oncoming acoustic fluctuations. By linearizing the flame model and recasting it into the classical time-lag N -τ formulation, the thermoacoustic system transfer function is calculated. Compared with the experimental measurement by injecting a broad-band white noise, good agreement is obtained.

  20. Sustained activity in hierarchical modular neural networks: self-organized criticality and oscillations

    Directory of Open Access Journals (Sweden)

    Sheng-Jun Wang

    2011-06-01

    Full Text Available Cerebral cortical brain networks possess a number of conspicuous features of structure and dynamics. First, these networks have an intricate, non-random organization. They are structured in a hierarchical modular fashion, from large-scale regions of the whole brain, via cortical areas and area subcompartments organized as structural and functional maps to cortical columns, and finally circuits made up of individual neurons. Second, the networks display self-organized sustained activity, which is persistent in the absence of external stimuli. At the systems level, such activity is characterized by complex rhythmical oscillations over a broadband background, while at the cellular level, neuronal discharges have been observed to display avalanches, indicating that cortical networks are at the state of self-organized criticality. We explored the relationship between hierarchical neural network organization and sustained dynamics using large-scale network modeling. It was shown that sparse random networks with balanced excitation and inhibition can sustain neural activity without external stimulation. We find that a hierarchical modular architecture can generate sustained activity better than random networks. Moreover, the system can simultaneously support rhythmical oscillations and self-organized criticality, which are not present in the respective random networks. The underlying mechanism is that each dense module cannot sustain activity on its own, but displays self-organized criticality in the presence of weak perturbations. The hierarchical modular networks provide the coupling among subsystems with self-organized criticality. These results imply that the hierarchical modular architecture of cortical networks plays an important role in shaping the ongoing spontaneous activity of the brain, potentially allowing the system to take advantage of both the sensitivityof critical state and predictability and timing of oscillations for efficient

  1. Self-sustained oscillations in nanoelectromechanical systems induced by Kondo resonance

    Science.gov (United States)

    Song, Taegeun; Kiselev, Mikhail N.; Kikoin, Konstantin; Shekhter, Robert I.; Gorelik, Leonid Y.

    2014-03-01

    We investigate the instability and dynamical properties of nanoelectromechanical systems represented by a single-electron device containing movable quantum dots attached to a vibrating cantilever via asymmetric tunnel contacts. The Kondo resonance in electron tunneling between the source and shuttle facilitates self-sustained oscillations originating from the strong coupling of mechanical and electronic/spin degrees of freedom. We analyze a stability diagram for the two-channel Kondo shuttling regime due to limitations given by the electromotive force acting on a moving shuttle, and find that the saturation oscillation amplitude is associated with the retardation effect of the Kondo cloud. The results shed light on possible ways to experimentally realize the Kondo-cloud dynamical probe by using high mechanical dissipation tunability as well as supersensitive detection of mechanical displacement.

  2. A numerical study of self-sustained oscillations in wind instruments

    Science.gov (United States)

    Rendon, Pablo L.; Velasco-Segura, Roberto

    2017-11-01

    The study of sustained notes in wind musical instruments in realistic conditions requires consideration of both excitation and propagation mechanisms, and the manner in which these two interact. Further, to model adequately acoustic propagation inside the instrument, a variety of competing effects must be taken into account, such as nonlinearity, thermoviscous attenuation and radiation at the open end. Physical solutions also involve some degree of feedback at the excitation end, and here we propose the simplest boundary conditions possible at this end, given by a simple harmonic oscillator with fixed stiffness. By feeding single-frequency acoustic waves into the system we are able to study the formation of self-sustained oscillations, which are stationary states associated with resonance frequencies, and also to observe transitory states. Visualizations are presented of waves traveling in both directions. As expected, resonance frequencies are dependent on the stiffness parameter, and this dependence is examined. The full-wave simulation is performed in the time domain over a 2D spatial domain assuming axial symmetry, and it is based on a previously validated open source code, using a finite volume method (FiVoNAGI) implemented in a GPU [Velasco-Segura & Rendn, 2015]. The authors acknowledge the financial support of DGAPA-UNAM through project PAPIIT IG100717.

  3. Is late Quaternary climate change governed by self-sustained oscillations in atmospheric CO2?

    Science.gov (United States)

    Wallmann, Klaus

    2014-05-01

    A simple earth system model is developed to simulate global carbon and phosphorus cycling over the late Quaternary. It is focused on the geological cycling of C and P via continental weathering, volcanic and metamorphic degassing, hydrothermal processes and burial at the seabed. A simple ocean model is embedded in this geological model where the global ocean is represented by surface water, thermocline and deep water boxes. Concentrations of dissolved phosphorus, dissolved inorganic carbon, and total alkalinity are calculated for each box. The partial pressure of CO2 in the atmosphere (pCO2A) is determined by exchange processes with the surface ocean and the continents. It serves as key prognostic model variable and is assumed to govern surface temperatures and global sea-level. The model is formulated as autonomous system, in which the governing equations have no explicit time-dependence. For certain parameter values, the model does not converge towards a steady-state but develops stable self-sustained oscillations. These free oscillations feature pCO2A minima and maxima consistent with the ice-core record when vertical mixing in the ocean is allowed to vary in response to pCO2A-controlled temperature change. A stable 100-kyr cycle with a rapid transition from glacial to interglacial conditions is obtained when additional non-linear equations are applied to calculate deep ocean mixing, iron fertilization and the depth of organic matter degradation as function of pCO2A-controlled surface temperature. The δ13C value of carbon in the ocean/atmosphere system calculated in these model runs is consistent with the benthic δ13C record. However, the simulated 13C depletion in the glacial ocean is not driven by the decline in terrestrial carbon stocks but by sea-level change controlling the rates of organic carbon burial and weathering at continental margins. The pCO2A- and δ13C oscillations develop without any form of external Milankovitch forcing. They are induced and

  4. Sustainability, collapse and oscillations in a simple World-Earth model

    Science.gov (United States)

    Nitzbon, Jan; Heitzig, Jobst; Parlitz, Ulrich

    2017-07-01

    The Anthropocene is characterized by close interdependencies between the natural Earth system and the global human society, posing novel challenges to model development. Here we present a conceptual model describing the long-term co-evolution of natural and socio-economic subsystems of Earth. While the climate is represented via a global carbon cycle, we use economic concepts to model socio-metabolic flows of biomass and fossil fuels between nature and society. A well-being-dependent parametrization of fertility and mortality governs human population dynamics. Our analysis focuses on assessing possible asymptotic states of the Earth system for a qualitative understanding of its complex dynamics rather than quantitative predictions. Low dimension and simple equations enable a parameter-space analysis allowing us to identify preconditions of several asymptotic states and hence fates of humanity and planet. These include a sustainable co-evolution of nature and society, a global collapse and everlasting oscillations. We consider different scenarios corresponding to different socio-cultural stages of human history. The necessity of accounting for the ‘human factor’ in Earth system models is highlighted by the finding that carbon stocks during the past centuries evolved opposing to what would ‘naturally’ be expected on a planet without humans. The intensity of biomass use and the contribution of ecosystem services to human well-being are found to be crucial determinants of the asymptotic state in a (pre-industrial) biomass-only scenario without capital accumulation. The capitalistic, fossil-based scenario reveals that trajectories with fundamentally different asymptotic states might still be almost indistinguishable during even a centuries-long transient phase. Given current human population levels, our study also supports the claim that besides reducing the global demand for energy, only the extensive use of renewable energies may pave the way into a

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-12-01

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

  6. Noise-sustained oscillation and synchronization of excitable media with stirring

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, Z. (Zoltan); Zhou, C. (Changsong); Kurths, J. (Jürgen),; Kiss, I. Z.

    2004-01-01

    Constructive effects of noise have been well studied in spatially extended systems. In most of these studies, the media are static, reaction-diffusion type, and the constructive effects are a consequence of the interplay between local excitation due to noise perturbation and propagation of excitation due to diffusion. Many chemical or biological processes occur in a fluid environment with mixing. In this paper, we investigate the interplay among noise, excitability, diffusion and mixing in excitable media advected by a chaotic flow, in a 2-d Fitz Hugh-Nagumo model described by the reaction-advection-diffusion equations. Without stirring, noise can only generate non-coherent excited patches of the static media. In the presence of stirring, we can observe three dynamical and pattern formation regimes: (i) Non-coherent excitation, when mixing is not strong enough to achieve synchronization of independent excitations developed at different locations; (ii) Coherent global excitation, when noise-perturbation survives the mixing to generate a synchronized excitation of the whole domain; and (iii) Homogenization, when strong enough stirring dilutes quickly those noise-induced local excitations. In the presence of an external sub-threshold periodic forcing, the period of-the noise-sustained oscillations can be locked by the forcing period with different ratios. Our results may be verified in experiments and find applications in population dynamics of oceanic ecological systems.

  7. Rhythmic and sustained oscillations in metabolism and gene expression of Cyanothece sp. ATCC 51142 under constant light

    Directory of Open Access Journals (Sweden)

    Sandeep Bhupendra Gaudana

    2013-12-01

    Full Text Available Cyanobacteria, a group of photosynthetic prokaryotes, oscillate between day and night time metabolisms with concomitant oscillations in gene expression in response to light/dark cycles (LD. The oscillations in gene expression have been shown to sustain in constant light (LL with a free running period of 24 h in a model cyanobacterium Synechococcus elongatus PCC 7942. However, equivalent oscillations in metabolism are not reported under LL in this non-nitrogen fixing cyanobacterium. Here we focus on Cyanothece sp. ATCC 51142, a unicellular, nitrogen-fixing cyanobacterium known to temporally separate the processes of oxygenic photosynthesis and oxygen-sensitive nitrogen fixation. In a recent report, metabolism of Cyanothece 51142 has been shown to oscillate between photosynthetic and respiratory phases under LL with free running periods that are temperature dependent but significantly shorter than the circadian period. Further, the oscillations shift to circadian pattern at moderate cell densities that are concomitant with slower growth rates. Here we take this understanding forward and demonstrate that the utradian rhythm under LL sustains at much higher cell densities when grown under turbulent regimes that simulate flashing light effect. Our results suggest that the ultradian rhythm in metabolism may be needed to support higher carbon and nitrogen requirements of rapidly growing cells under LL. With a comprehensive Real time PCR based gene expression analysis we account for key regulatory interactions and demonstrate the interplay between clock genes and the genes of key metabolic pathways. Further, we observe that several genes that peak at dusk in Synechococcus peak at dawn in Cyanothece and vice versa. The circadian rhythm of this organism appears to be more robust with peaking of genes in anticipation of the ensuing photosynthetic and respiratory metabolic phases.

  8. Semiconductor lasers driven by self-sustained chaotic electronic oscillators and applications to optical chaos cryptography.

    Science.gov (United States)

    Kingni, Sifeu Takougang; Mbé, Jimmi Hervé Talla; Woafo, Paul

    2012-09-01

    In this work, we numerically study the dynamics of vertical cavity surface emitting laser (VCSEL) firstly when it is driven by Chua's oscillator, secondly in case where it is driven by a broad frequency spectral bandwidth chaotic oscillator developed by Nana et al. [Commun. Nonlinear Sci. Numer. Simul. 14, 2266 (2009)]. We demonstrated that the VCSEL generated robust chaotic dynamics compared to the ones found in VCSEL subject to a sinusoidally modulated current and therefore it is more suitable for chaos encryption techniques. The synchronization characteristics and the communication performances of unidirectional coupled VCSEL driven by the broad frequency spectral bandwidth chaotic oscillators are investigated numerically. The results show that high-quality synchronization and transmission of messages can be realized for suitable system parameters. Chaos shift keying method is successfully applied to encrypt a message at a high bitrate.

  9. On the failure of sustained oscillations in the bromate/hypophosphite-acetone/dual catalyst flow system

    Science.gov (United States)

    Nogueira, Paulo A.; Faria, Roberto B.; Varela, Hamilton

    2013-02-01

    In this report we present experimental results on the dynamical behavior of the bromate/hypophosphite-acetone/dual catalyst system. According to our findings we state that this two-catalyst system does not show oscillations under flow conditions. Our discussion is based on the sequential action of the two catalysts system.

  10. Optimization of the Close-to-Carrier Phase Noise in a CMOS-MEMS Oscillator Using a Phase Tunable Sustaining-Amplifier.

    Science.gov (United States)

    Sobreviela, Guillermo; Riverola, Martin; Torres, Francesc; Uranga, Arantxa; Barniol, Nuria

    2017-05-01

    In this paper, the phase noise of a 24-MHz complimentary metal-oxide-semiconductor microelectromechanical systems (CMOS-MEMS) oscillator with zero-level vacuum package is studied. We characterize and analyze the nonlinear regime of each one of the modules that compose the oscillator (CMOS sustaining-amplifier and MEMS resonator). As we show, the presented resonator exhibits a high nonlinear behavior. Such a fact is exploited as a mechanism to stabilize the oscillation amplitude, allowing us to maintain the sustaining-amplifier working in the linear regime. Consequently, the nonlinear resonator becomes the main close-to-carrier phase noise source. The sustaining amplifier, which functions as a phase shifter, was developed such that MEMS operation point optimization could be achieved without an increase in circuitry modules. Therefore, the system saves on area and power, and is able to improve the phase noise 26 dBc/Hz (at 1-kHz carrier frequency offset).

  11. Sustained oscillations, irregular firing, and chaotic dynamics in hierarchical modular networks with mixtures of electrophysiological cell types.

    Science.gov (United States)

    Tomov, Petar; Pena, Rodrigo F O; Zaks, Michael A; Roque, Antonio C

    2014-01-01

    The cerebral cortex exhibits neural activity even in the absence of external stimuli. This self-sustained activity is characterized by irregular firing of individual neurons and population oscillations with a broad frequency range. Questions that arise in this context, are: What are the mechanisms responsible for the existence of neuronal spiking activity in the cortex without external input? Do these mechanisms depend on the structural organization of the cortical connections? Do they depend on intrinsic characteristics of the cortical neurons? To approach the answers to these questions, we have used computer simulations of cortical network models. Our networks have hierarchical modular architecture and are composed of combinations of neuron models that reproduce the firing behavior of the five main cortical electrophysiological cell classes: regular spiking (RS), chattering (CH), intrinsically bursting (IB), low threshold spiking (LTS), and fast spiking (FS). The population of excitatory neurons is built of RS cells (always present) and either CH or IB cells. Inhibitory neurons belong to the same class, either LTS or FS. Long-lived self-sustained activity states in our network simulations display irregular single neuron firing and oscillatory activity similar to experimentally measured ones. The duration of self-sustained activity strongly depends on the initial conditions, suggesting a transient chaotic regime. Extensive analysis of the self-sustained activity states showed that their lifetime expectancy increases with the number of network modules and is favored when the network is composed of excitatory neurons of the RS and CH classes combined with inhibitory neurons of the LTS class. These results indicate that the existence and properties of the self-sustained cortical activity states depend on both the topology of the network and the neuronal mixture that comprises the network.

  12. Sustained oscillations, irregular firing and chaotic dynamics in hierarchical modular networks with mixtures of electrophysiological cell types

    Directory of Open Access Journals (Sweden)

    Petar eTomov

    2014-09-01

    Full Text Available The cerebral cortex exhibits neural activity even in the absence of externalstimuli. This self-sustained activity is characterized by irregular firing ofindividual neurons and population oscillations with a broad frequency range.Questions that arise in this context, are: What are the mechanismsresponsible for the existence of neuronal spiking activity in the cortexwithout external input? Do these mechanisms depend on the structural organization of the cortical connections? Do they depend onintrinsic characteristics of the cortical neurons? To approach the answers to these questions, we have used computer simulations of cortical network models. Our networks have hierarchical modular architecture and are composedof combinations of neuron models that reproduce the firing behavior of the five main cortical electrophysiological cell classes: regular spiking (RS, chattering (CH, intrinsically bursting (IB, low threshold spiking (LTS and fast spiking (FS. The population of excitatory neurons is built of RS cells(always present and either CH or IB cells. Inhibitoryneurons belong to the same class, either LTS or FS. Long-lived self-sustained activity states in our networksimulations display irregular single neuron firing and oscillatoryactivity similar to experimentally measured ones. The duration of self-sustained activity strongly depends on the initial conditions,suggesting a transient chaotic regime. Extensive analysis of the self-sustainedactivity states showed that their lifetime expectancy increases with the numberof network modules and is favored when the network is composed of excitatory neurons of the RS and CH classes combined with inhibitory neurons of the LTS class. These results indicate that the existence and properties of the self-sustained cortical activity states depend on both the topology of the network and the neuronal mixture that comprises the network.

  13. A memristor-based third-order oscillator: beyond oscillation

    Science.gov (United States)

    Talukdar, A.; Radwan, A. G.; Salama, K. N.

    2011-09-01

    This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.

  14. A memristor-based third-order oscillator: beyond oscillation

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2012-10-06

    This paper demonstrates the first third-order autonomous linear time variant circuit realization that enhances parametric oscillation through the usage of memristor in conventional oscillators. Although the output has sustained oscillation, the linear features of the conventional oscillators become time dependent. The poles oscillate in nonlinear behavior due to the oscillation of memristor resistance. The mathematical formulas as well as SPICE simulations are introduced for the memristor-based phase shift oscillator showing a great matching.

  15. The CAN-In network: A biologically inspired model for self-sustained theta oscillations and memory maintenance in the hippocampus.

    Science.gov (United States)

    Giovannini, Francesco; Knauer, Beate; Yoshida, Motoharu; Buhry, Laure

    2017-04-01

    During working memory tasks, the hippocampus exhibits synchronous theta-band activity, which is thought to be correlated with the short-term memory maintenance of salient stimuli. Recent studies indicate that the hippocampus contains the necessary circuitry allowing it to generate and sustain theta oscillations without the need of extrinsic drive. However, the cellular and network mechanisms supporting synchronous rhythmic activity are far from being fully understood. Based on electrophysiological recordings from hippocampal pyramidal CA1 cells, we present a possible mechanism for the maintenance of such rhythmic theta-band activity in the isolated hippocampus. Our model network, based on the Hodgkin-Huxley formalism, comprising pyramidal neurons equipped with calcium-activated nonspecific cationic (CAN) ion channels, is able to generate and sustain synchronized theta oscillations (4-12 Hz), following a transient stimulation. The synchronous network activity is maintained by an intrinsic CAN current (I CAN ), in the absence of constant external input. When connecting the pyramidal-CAN network to fast-spiking inhibitory interneurons, the dynamics of the model reveal that feedback inhibition improves the robustness of fast theta oscillations, by tightening the synchronization of the pyramidal CAN neurons. The frequency and power of the theta oscillations are both modulated by the intensity of the I CAN , which allows for a wide range of oscillation rates within the theta band. This biologically plausible mechanism for the maintenance of synchronous theta oscillations in the hippocampus aims at extending the traditional models of septum-driven hippocampal rhythmic activity. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  16. Neurodynamic oscillators

    Science.gov (United States)

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

    1995-01-01

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

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

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2012-07-28

    Traditionally, the necessary and sufficient condition for any system to be oscillating is that its poles are located on the imaginary (jω) axis. In this paper, for the first time, we have shown that systems can oscillate with time-domain oscillating poles. The idea is verified using a Memristor based Wien oscillator. Sustained oscillations are observed without having the poles of the system fixed on the imaginary axis and the oscillating behavior of the system poles is reported. The oscillating resistance and triangular shape of FFT are also demonstrated with mathematical reasoning and simulation results to support the unusual and surprising characteristics. © 2009 IEEE.

  18. Quantum Oscillators

    CERN Document Server

    Blaise, Paul

    2011-01-01

    An invaluable reference for an overall but simple approach to the complexity of quantum mechanics viewed through quantum oscillators Quantum oscillators play a fundamental role in many areas of physics; for instance, in chemical physics with molecular normal modes, in solid state physics with phonons, and in quantum theory of light with photons. Quantum Oscillators is a timely and visionary book which presents these intricate topics, broadly covering the properties of quantum oscillators which are usually dispersed in the literature at varying levels of detail and often combined with other p

  19. Chemical Oscillations

    Indian Academy of Sciences (India)

    processes at the cellular level like the glycolytic pathway, peroxi- dase-catalysed reaction or the biosynthesis of certain proteins. A systematic study of oscillating chemical reactions is of consider- able interest, since these oscillating reactions can be used as prototype examples of the behaviours possible in reactions gov-.

  20. Fibonacci oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Arik, M. (Istanbul Technical Univ. (Turkey). Dept. of Mathematics Bogazici Univ., Istanbul (Turkey). Dept. of Physics); Demircan, E.; Turgut, T. (Texas Univ., Austin, TX (United States). Dept. of Physics); Ekinci, L.; Mungan, M. (Bogazici Univ., Istanbul (Turkey). Dept. of Physics)

    1992-07-01

    We discuss the properties of oscillators whose spectrum is given by a generalized Fibonacci sequence. The properties include: Invariance under the unitary quantum group, generalized angular momentum, coherent states and difference calculus, relativistic interpretation. (orig.).

  1. Activation of Cdc42 is necessary for sustained oscillations of Ca2+ and PIP2 stimulated by antigen in RBL mast cells

    Directory of Open Access Journals (Sweden)

    Marcus M. Wilkes

    2014-07-01

    Full Text Available Antigen stimulation of mast cells via FcεRI, the high-affinity receptor for IgE, triggers a signaling cascade that requires Ca2+ mobilization for exocytosis of secretory granules during the allergic response. To characterize the role of Rho GTPases in FcεRI signaling, we utilized a mutant RBL cell line, B6A4C1, that is deficient in antigen-stimulated Cdc42 activation important for these processes. Recently the importance of stimulated intracellular oscillations has emerged, and we find that B6A4C1 cells exhibit severely attenuated Ca2+ oscillations in response to antigen, which are restored to wild-type RBL-2H3 levels by expression of constitutively active Cdc42 G12V or by a GEF for Cdc42, DOCK7, but not when the C-terminal di-arginine motif of active Cdc42 is mutated to di-glutamine. We found that antigen-stimulated FcεRI endocytosis, which occurs independently of Ca2+ mobilization, is also defective in B6A4C1 cells, and Cdc42 G12V reconstitutes this response as well. Thus, activation of Cdc42 occurs prior to and is critical for antigen-stimulated pathways leading separately to both Ca2+ mobilization and receptor endocytosis. Accounting for these downstream functional consequences, we show that Cdc42 G12V reconstitutes antigen-stimulated oscillations of phosphatidylinositol 4,5-bisphosphate (PIP2 at the plasma membrane in mutant B6A4C1 cells, pointing to Cdc42 participation in the regulation of stimulated PIP2 synthesis.

  2. Prominence Oscillations

    Directory of Open Access Journals (Sweden)

    Iñigo Arregui

    2012-04-01

    Full Text Available Prominences are intriguing, but poorly understood, magnetic structures of the solar corona. The dynamics of solar prominences has been the subject of a large number of studies, and of particular interest is the study of prominence oscillations. Ground- and space-based observations have confirmed the presence of oscillatory motions in prominences and they have been interpreted in terms of magnetohydrodynamic (MHD waves. This interpretation opens the door to perform prominence seismology, whose main aim is to determine physical parameters in magnetic and plasma structures (prominences that are difficult to measure by direct means. Here, we review the observational information gathered about prominence oscillations as well as the theoretical models developed to interpret small amplitude oscillations and their temporal and spatial attenuation. Finally, several prominence seismology applications are presented.

  3. Chromosperic oscillations

    NARCIS (Netherlands)

    Rutten, R.J.

    1999-01-01

    This review concentrates on the quiet-Sun chromosphere. Its internetwork areas are dynamically dominated by the so-called chromospheric three-minute oscillation. They are interpretationally dominated by the so-called Ca II K 2V and H 2V grains. The main points of this review are that the one

  4. FEL Oscillators

    Energy Technology Data Exchange (ETDEWEB)

    George Neil

    2003-05-12

    FEL Oscillators have been around since 1977 providing not only a test bed for the physics of Free Electron Lasers and electron/photon interactions but as a workhorse of scientific research. More than 30 FEL oscillators are presently operating around the world spanning a wavelength range from the mm region to the ultraviolet using DC and rf linear accelerators and storage rings as electron sources. The characteristics that have driven the development of these sources are the desire for high peak and average power, high micropulse energies, wavelength tunability, timing flexibility, and wavelengths that are unavailable from more conventional laser sources. Substantial user programs have been performed using such sources encompassing medicine, biology, solid state research, atomic and molecular physics, effects of non-linear fields, surface science, polymer science, pulsed laser vapor deposition, to name just a few.

  5. Oscillators and Eigenvalues

    DEFF Research Database (Denmark)

    Lindberg, Erik

    1997-01-01

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

  6. Oscillator circuits

    CERN Document Server

    Graf, Rudolf F

    1996-01-01

    This series of circuits provides designers with a quick source for oscillator circuits. Why waste time paging through huge encyclopedias when you can choose the topic you need and select any of the specialized circuits sorted by application?This book in the series has 250-300 practical, ready-to-use circuit designs, with schematics and brief explanations of circuit operation. The original source for each circuit is listed in an appendix, making it easy to obtain additional information.Ready-to-use circuits.Grouped by application for easy look-up.Circuit source listing

  7. Power oscillation damping controller

    DEFF Research Database (Denmark)

    2012-01-01

    A power oscillation damping controller is provided for a power generation device such as a wind turbine device. The power oscillation damping controller receives an oscillation indicating signal indicative of a power oscillation in an electricity network and provides an oscillation damping control...... signal in response to the oscillation indicating signal, by processing the oscillation damping control signal in a signal processing chain. The signal processing chain includes a filter configured for passing only signals within a predetermined frequency range....

  8. Generalized model for Memristor-based Wien family oscillators

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2012-07-23

    In this paper, we report the unconventional characteristics of Memristor in Wien oscillators. Generalized mathematical models are developed to analyze four members of the Wien family using Memristors. Sustained oscillation is reported for all types though oscillating resistance and time dependent poles are present. We have also proposed an analytical model to estimate the desired amplitude of oscillation before the oscillation starts. These Memristor-based oscillation results, presented for the first time, are in good agreement with simulation results. © 2011 Elsevier Ltd.

  9. Burst Oscillation Studies with NICER

    Science.gov (United States)

    Mahmoodifar, Simin; Strohmayer, Tod E.

    2017-08-01

    Type I X-ray bursts are thermonuclear flashes observed from the surfaces of accreting neutron stars in Low Mass X-ray Binaries. Oscillations have been observed during the rise and/or decay of some of these X-ray bursts. Those seen during the rise can be well explained by a spreading hot spot model, but large amplitude oscillations in the decay phase remain mysterious because of the absence of a clear-cut source of asymmetry. Here we present the results of our computations of the light curves and amplitudes of oscillations in X-ray burst models that realistically account for both flame spreading and subsequent cooling. For the cooling phase of the burst we use two simple phenomenological models. The first considers asymmetric cooling that can achieve high amplitudes in the tail. The second considers a sustained temperature pattern on the stellar surface that is produced by r-modes propagating in the surface fluid ocean of the star. We will present some simulated burst light curves/spectra using these models and NICER response files, and will show the capabilities of NICER to detect and study burst oscillations. NICER will enable us to study burst oscillations in the energy band below ~3 keV, where there has been no previous measurements of these phenomena.

  10. A new halogen-free chemical oscillator: the reaction between permanganate ion and ninhydrin in a continuously stirred tank reactor

    Science.gov (United States)

    Treindl, Ľudovít; Nagy, Arpád

    1987-07-01

    The reaction between permanganate ion and ninhydrin in the presence of phosphoric acid in aqueous solution shows sustained oscillations in a continuously stirred tank reactor (CSTR). It exhibits a kinetic bistability between an oscillatory and a stationary state. Our new oscillating system seems to be a second permanganate chemical oscillator, thus broadening the small group of non-halogen-based chemical oscillators.

  11. Nonlinear Dynamics of Memristor Based 2nd and 3rd Order Oscillators

    KAUST Repository

    Talukdar, Abdul Hafiz

    2011-05-01

    Exceptional behaviours of Memristor are illustrated in Memristor based second order (Wien oscillator) and third order (phase shift oscillator) oscillator systems in this Thesis. Conventional concepts about sustained oscillation have been argued by demonstrating the possibility of sustained oscillation with oscillating resistance and dynamic poles. Mathematical models are also proposed for analysis and simulations have been presented to support the surprising characteristics of the Memristor based oscillator systems. This thesis also describes a comparative study among the Wien family oscillators with one Memristor. In case of phase shift oscillator, one Memristor and three Memristors systems are illustrated and compared to generalize the nonlinear dynamics observed for both 2nd order and 3rd order system. Detail explanations are provided with analytical models to simplify the unconventional properties of Memristor based oscillatory systems.

  12. Microelectronic oscillator, 2

    Science.gov (United States)

    Kleinberg, L. L.

    1969-01-01

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

  13. Oscillating heat pipes

    CERN Document Server

    Ma, Hongbin

    2015-01-01

    This book presents the fundamental fluid flow and heat transfer principles occurring in oscillating heat pipes and also provides updated developments and recent innovations in research and applications of heat pipes. Starting with fundamental presentation of heat pipes, the focus is on oscillating motions and its heat transfer enhancement in a two-phase heat transfer system. The book covers thermodynamic analysis, interfacial phenomenon, thin film evaporation,  theoretical models of oscillating motion and heat transfer of single phase and two-phase flows, primary  factors affecting oscillating motions and heat transfer,  neutron imaging study of oscillating motions in an oscillating heat pipes, and nanofluid’s effect on the heat transfer performance in oscillating heat pipes.  The importance of thermally-excited oscillating motion combined with phase change heat transfer to a wide variety of applications is emphasized. This book is an essential resource and learning tool for senior undergraduate, gradua...

  14. Phenomenology of neutrino oscillations

    Indian Academy of Sciences (India)

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

  15. Rayleigh-type parametric chemical oscillation.

    Science.gov (United States)

    Ghosh, Shyamolina; Ray, Deb Shankar

    2015-09-28

    We consider a nonlinear chemical dynamical system of two phase space variables in a stable steady state. When the system is driven by a time-dependent sinusoidal forcing of a suitable scaling parameter at a frequency twice the output frequency and the strength of perturbation exceeds a threshold, the system undergoes sustained Rayleigh-type periodic oscillation, wellknown for parametric oscillation in pipe organs and distinct from the usual forced quasiperiodic oscillation of a damped nonlinear system where the system is oscillatory even in absence of any external forcing. Our theoretical analysis of the parametric chemical oscillation is corroborated by full numerical simulation of two well known models of chemical dynamics, chlorite-iodine-malonic acid and iodine-clock reactions.

  16. Star-shaped oscillations of Leidenfrost drops

    Science.gov (United States)

    Ma, Xiaolei; Liétor-Santos, Juan-José; Burton, Justin C.

    2017-03-01

    We experimentally investigate the self-sustained, star-shaped oscillations of Leidenfrost drops. The drops levitate on a cushion of evaporated vapor over a heated, curved surface. We observe modes with n =2 -13 lobes around the drop periphery. We find that the wavelength of the oscillations depends only on the capillary length of the liquid and is independent of the drop radius and substrate temperature. However, the number of observed modes depends sensitively on the liquid viscosity. The dominant frequency of pressure variations in the vapor layer is approximately twice the drop oscillation frequency, consistent with a parametric forcing mechanism. Our results show that the star-shaped oscillations are driven by capillary waves of a characteristic wavelength beneath the drop and that the waves are generated by a large shear stress at the liquid-vapor interface.

  17. 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...

  18. Nature's Autonomous Oscillators

    Science.gov (United States)

    Mayr, H. G.; Yee, J.-H.; Mayr, M.; Schnetzler, R.

    2012-01-01

    Nonlinearity is required to produce autonomous oscillations without external time dependent source, and an example is the pendulum clock. The escapement mechanism of the clock imparts an impulse for each swing direction, which keeps the pendulum oscillating at the resonance frequency. Among nature's observed autonomous oscillators, examples are the quasi-biennial oscillation and bimonthly oscillation of the Earth atmosphere, and the 22-year solar oscillation. The oscillations have been simulated in numerical models without external time dependent source, and in Section 2 we summarize the results. Specifically, we shall discuss the nonlinearities that are involved in generating the oscillations, and the processes that produce the periodicities. In biology, insects have flight muscles, which function autonomously with wing frequencies that far exceed the animals' neural capacity; Stretch-activation of muscle contraction is the mechanism that produces the high frequency oscillation of insect flight, discussed in Section 3. The same mechanism is also invoked to explain the functioning of the cardiac muscle. In Section 4, we present a tutorial review of the cardio-vascular system, heart anatomy, and muscle cell physiology, leading up to Starling's Law of the Heart, which supports our notion that the human heart is also a nonlinear oscillator. In Section 5, we offer a broad perspective of the tenuous links between the fluid dynamical oscillators and the human heart physiology.

  19. Oscillations of disks

    CERN Document Server

    Kato, Shoji

    2016-01-01

    This book presents the current state of research on disk oscillation theory, focusing on relativistic disks and tidally deformed disks. Since the launch of the Rossi X-ray Timing Explorer (RXTE) in 1996, many high-frequency quasiperiodic oscillations (HFQPOs) have been observed in X-ray binaries. Subsequently, similar quasi-periodic oscillations have been found in such relativistic objects as microquasars, ultra-luminous X-ray sources, and galactic nuclei. One of the most promising explanations of their origin is based on oscillations in relativistic disks, and a new field called discoseismology is currently developing. After reviewing observational aspects, the book presents the basic characteristics of disk oscillations, especially focusing on those in relativistic disks. Relativistic disks are essentially different from Newtonian disks in terms of several basic characteristics of their disk oscillations, including the radial distributions of epicyclic frequencies. In order to understand the basic processes...

  20. Noise induced oscillations and coherence resonance in a generic model of the nonisothermal chemical oscillator

    Science.gov (United States)

    Simakov, David S. A.; Pérez-Mercader, Juan

    2013-08-01

    Oscillating chemical reactions are common in biological systems and they also occur in artificial non-biological systems. Generally, these reactions are subject to random fluctuations in environmental conditions which translate into fluctuations in the values of physical variables, for example, temperature. We formulate a mathematical model for a nonisothermal minimal chemical oscillator containing a single negative feedback loop and study numerically the effects of stochastic fluctuations in temperature in the absence of any deterministic limit cycle or periodic forcing. We show that noise in temperature can induce sustained limit cycle oscillations with a relatively narrow frequency distribution and some characteristic frequency. These properties differ significantly depending on the noise correlation. Here, we have explored white and colored (correlated) noise. A plot of the characteristic frequency of the noise induced oscillations as a function of the correlation exponent shows a maximum, therefore indicating the existence of autonomous stochastic resonance, i.e. coherence resonance.

  1. The Oscillator Principle of Nature

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2012-01-01

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

  2. A Conspiracy of Oscillators

    DEFF Research Database (Denmark)

    Hjorth, Poul G.

    2008-01-01

    We discuss nonlinear mechanical systems containing several oscillators whose frequecies are all much higher than frequencies associated with the remaining degrees of freedom. In this situation a near constant of the motion, an adiabatic invariant, exists which is the sum of all the oscillator...

  3. Hyperchaotic Oscillator with Gyrators

    DEFF Research Database (Denmark)

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

    1997-01-01

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

  4. Grazing Impact Oscillations

    NARCIS (Netherlands)

    Weger, J.G.; Water, van de W.; Molenaar, J.

    2000-01-01

    An impact oscillator is a periodically driven system that hits a wall when its amplitude exceeds a critical value. We study impact oscillations where collisions with the wall are with near-zero velocity (grazing impacts). A characteristic feature of grazing impact dynamics is a geometrically

  5. 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...... oscillators are investigated demonstrating synchronization by means of only one properly selected variable....

  6. Prediction of resonant oscillation

    DEFF Research Database (Denmark)

    2010-01-01

    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...

  7. Magnetostatic wave oscillator frequencies

    Science.gov (United States)

    Sethares, J. C.; Stiglitz, M. R.; Weinberg, I. J.

    1981-03-01

    The frequencies of magnetostatic wave (MSW) oscillators employing three principal modes of propagation, surface (MSSW), forward (MSFVW), and backward (MSBVW) volume waves, have been investigated. Previous (MSW) oscillator papers dealt with MSSW. Oscillators were fabricated using LPE-YIG MSW delay lines in a feedback loop of a 2-4 GHz amplifier. Wide and narrow band transducers were employed. Oscillator frequency as a function of biasing field is in agreement with a theoretical analysis. The analysis predicts frequency in terms of material parameters, biasing field, and transducer geometry. With wide band transducers a comb of frequencies is generated. Narrow band transducers for MSSW and MSFVW select a single mode; and MSBVW selects two modes. Spurious modes, attributed to instrumentation, are more than 20 dB below the main response, and bandwidths are less than 0.005 percent. No other spurious modes are observed. MSW oscillators produce clean electronically tunable signals and appear attractive in frequency agile systems.

  8. Economic Inequality, Educational Inequity, and Reduced Career Opportunity: A Self-Perpetuating Cycle?

    Science.gov (United States)

    Torraco, Richard

    2018-01-01

    Economic inequality--the income gap between the wealthy and the poor--is increasing. Educational inequity has also increased with low-income students less likely to complete college than their wealthier counterparts. As the gap widens between the education "haves" and "have-nots," those with inadequate education are faced with…

  9. A Self-Perpetuating Catalyst for the Production of Complex Organic Molecules in Protostellar Nebulae

    Science.gov (United States)

    Nuth, Joseph A.; Johnson, N. M.

    2010-01-01

    The formation of abundant carbonaceous material in meteorites is a long standing problem and an important factor in the debate on the potential for the origin of life in other stellar systems. Many mechanisms may contribute to the total organic content in protostellar nebulae, ranging from organics formed via ion-molecule and atom-molecule reactions in the cold dark clouds from which such nebulae collapse, to similar ion-molecule and atom-molecule reactions in the dark regions of the nebula far from the proto star, to gas phase reactions in sub-nebulae around growing giant planets and in the nebulae themselves. The Fischer-Tropsch-type (FTT) catalytic reduction of CO by hydrogen was once the preferred model for production of organic materials in the primitive solar nebula. The Haber-Bosch catalytic reduction of N2 by hydrogen was thought to produce the reduced nitrogen found in meteorites. However, the clean iron metal surfaces that catalyze these reactions are easily poisoned via reaction with any number of molecules, including the very same complex organics that they produce and both reactions work more efficiently in the hot regions of the nebula. We have demonstrated that many grain surfaces can catalyze both FTT and HB-type reactions, including amorphous iron and magnesium silicates, pure silica smokes as well as several minerals. Although none work as well as pure iron grains, and all produce a wide range of organic products rather than just pure methane, these materials are not truly catalysts.

  10. Neutrino Oscillation Physics

    CERN Document Server

    Kayser, Boris

    2014-04-10

    To complement the neutrino-physics lectures given at the 2011 International School on Astro Particle Physics devoted to Neutrino Physics and Astrophysics (ISAPP 2011; Varenna, Italy), at the 2011 European School of High Energy Physics (ESHEP 2011; Cheila Gradistei, Romania), and, in modified form, at other summer schools, we present here a written description of the physics of neutrino oscillation. This description is centered on a new way of deriving the oscillation probability. We also provide a brief guide to references relevant to topics other than neutrino oscillation that were covered in the lectures.

  11. Classical oscillator driven by an oscillating chirped force

    NARCIS (Netherlands)

    Khachatryan, A.G.; van Goor, F.A.; Boller, Klaus J.

    2006-01-01

    The motion of a classical (harmonic) oscillator is studied in the case where the oscillator is driven by a pulsed oscillating force with a frequency varying in time (frequency chirp). The amplitude and phase of the oscillations left after the pulsed force in dependence on the profile and strength of

  12. High frequency nanotube oscillator

    Science.gov (United States)

    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.

  13. Neutrino anomalies without oscillations

    Indian Academy of Sciences (India)

    conventional' neutrino oscillations induced by mass-mixing. Several of these require non-zero neutrino masses as well. Author Affiliations. Sandip Pakvasa1. Department of Physics and Astronomy, University of Hawaii, Honolulu, HI 96822, USA ...

  14. 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.

  15. Energy substrates that fuel fast neuronal network oscillations

    Directory of Open Access Journals (Sweden)

    Lukas V. Galow

    2014-12-01

    Full Text Available Fast neuronal network oscillations in the gamma-frequency band (30-100 Hz provide a fundamental mechanism of complex neuronal information processing in the hippocampus and neocortex of mammals. Gamma oscillations have been implicated in higher brain functions such as sensory perception, motor activity and memory formation. The oscillations emerge from precise synapse interactions between excitatory principal neurons such as pyramidal cells and inhibitory GABAergic interneurons, and they are associated with high energy expenditure. However, both energy substrates and metabolic pathways that are capable to power cortical gamma oscillations have been less defined. Here, we investigated the energy sources fueling persistent gamma oscillations in the CA3 subfield of organotypic hippocampal slice cultures of the rat. This preparation permits superior oxygen supply as well as fast application of glucose, glycolytic metabolites or drugs such as glycogen phosphorylase inhibitor during extracellular recordings of the local field potential. Our findings are: (i gamma oscillations persist in the presence of glucose (10 mmol/L for greater than 60 minutes in slice cultures while (ii lowering glucose levels (2.5 mmol/L significantly reduces the amplitude of the oscillation. (iii Gamma oscillations are absent at low concentration of lactate (2 mmol/L. (iv Gamma oscillations persist at high concentration (20 mmol/L of either lactate or pyruvate, albeit showing significant reductions in the amplitude. (v The breakdown of glycogen significantly delays the decay of gamma oscillations during glucose deprivation. However, when glucose is present, the turnover of glycogen is not essential to sustain gamma oscillations. Our study shows that fast neuronal network oscillations can be fueled by different energy-rich substrates, with glucose being most effective.

  16. solar neutrino oscillation phenomenology

    Indian Academy of Sciences (India)

    The sMA region and a large part of the vacuum oscillation region are seen to have been washed away with the inclusion of the sK spectrum data. In the left panel of figure 4 we show the dependence of the probabilities on energy. In the sMA and the VO oscillation regions the probability has a non- monotonic dependence ...

  17. Self-oscillation

    CERN Document Server

    Jenkins, Alejandro

    2011-01-01

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

  18. Cyclic Variations in Sustained Human Performance

    Science.gov (United States)

    Aue, William R.; Arruda, James E.; Kass, Steven J.; Stanny, Claudia J.

    2009-01-01

    Biological rhythms play a prominent role in the modulation of human physiology and behavior. [Smith, K., Valentino, D., & Arruda, J. (2003). "Rhythmic oscillations in the performance of a sustained attention task." "Journal of Clinical and Experimental Neuropsychology," 25, 561-570] suggested that sustained human performance may systematically…

  19. Oscillations in neutron stars

    Energy Technology Data Exchange (ETDEWEB)

    Hoeye, Gudrun Kristine

    1999-07-01

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

  20. Non-linear oscillations

    CERN Document Server

    Hagedorn, Peter

    1982-01-01

    Thoroughly revised and updated, the second edition of this concise text provides an engineer's view of non-linear oscillations, explaining the most important phenomena and solution methods. Non-linear descriptions are important because under certain conditions there occur large deviations from the behaviors predicted by linear differential equations. In some cases, completely new phenomena arise that are not possible in purely linear systems. The theory of non-linear oscillations thus has important applications in classical mechanics, electronics, communications, biology, and many other branches of science. In addition to many other changes, this edition has a new section on bifurcation theory, including Hopf's theorem.

  1. Brownian parametric oscillators

    Science.gov (United States)

    Zerbe, Christine; Jung, Peter; Hänggi, Peter

    1994-05-01

    We discuss the stochastic dynamics of dissipative, white-noise-driven Floquet oscillators, characterized by a time-periodic stiffness. Thus far, little attention has been paid to these exactly solvable nonstationary systems, although they carry a rich potential for several experimental applications. Here, we calculate and discuss the mean values and variances, as well as the correlation functions and the Floquet spectrum. As one main result, we find for certain parameter values that the fluctuations of the position coordinate are suppressed as compared to the equilibrium value of a harmonic oscillator (parametric squeezing).

  2. 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...

  3. Correlated EMG Oscillations between Antagonists during Cocontraction in Men.

    Science.gov (United States)

    Yoshitake, Yasuhide; Kanehisa, Hiroaki; Shinohara, Minoru

    2017-03-01

    The purpose of this study was to determine the modulation of common low-frequency oscillations in pools of motor units across antagonistic muscles because of the difference in the activation level of pools of spinal motor neurons and the presence of neuromuscular fatigue during intended cocontraction. Ten healthy young men (21.8 ± 1.5 yr) performed intended steady cocontractions of elbow flexors and extensors at maximal and a submaximal (10% of maximal EMG) effort. The submaximal cocontraction was repeated after sustained maximal contraction of elbow flexors. Surface EMG was recorded from the biceps brachii and triceps brachii muscles. Correlated EMG oscillations between the antagonistic muscles were quantified by the cross-correlation function (CCF) using rectified EMG for the EMG for the 3- to 15-Hz bands. The positive CCF peak in rectified EMG EMG, a negative CCF peak (i.e., out-of-phase oscillations) during submaximal cocontraction was smaller compared with maximal cocontraction but increased after the sustained contraction. Across subjects, the degree of reduction in maximal EMG amplitude after the sustained contraction was correlated with the amount of change in the CCF peak in EMG oscillations between antagonistic muscles occur during intended cocontraction, and 2) the magnitude of these correlated oscillations increases with the activation level of pools of spinal motor neurons and neuromuscular fatigue.

  4. A simple violin oscillator

    Science.gov (United States)

    Jones, R. T.

    1976-01-01

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

  5. 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...

  6. Phenomenology of neutrino oscillations

    CERN Document Server

    Kobzarev, I Yu; Okun, Lev Borisovich; Shchepkin, M G

    1980-01-01

    A complete phenomenological description of neutrino oscillations is given. The most general form of the mass matrix of N types of neutrino and of the matrix of neutrino mixing in the left charged current is analyzed. Measuring the parameters of the charged current matrix in oscillatory experiments and in the experimental studies of the beta -decay electron spectra, is discussed. (20 refs).

  7. 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.

  8. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

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

    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...

  9. Sustainable Food & Sustainable Economics

    OpenAIRE

    Alvarez, Mavis Dora

    2012-01-01

    Cuba today is immersed in a very intense process of perfecting its agricultural production structures with the goal of making them more efficient and sustainable in their economic administration and in their social and environmental management. Agricultural cooperatives in Cuba have the responsibility of producing on 73% of the country's farmland. Their contributions are decisive to developing agricultural production and to ensuring more and better food for the population, in addition to redu...

  10. Photonic local oscillator development

    Science.gov (United States)

    Kimberk, Robert; Tong, Edward; Hunter, Todd R.; Christensen, Robert; Blundell, Ray

    2006-12-01

    In the receiver lab, we have developed a 200 GHz to 230 GHz local oscillator constructed from mostly commercially available 1550 nm laser communication components. Theoretical and experimental work show that the laser adds negligible phase noise to this photonic local oscillator system and that spectral purity and phase stability are similar to Gunn oscillator based local oscillator output. The optical path consists of a single 1550 nm diode laser, a lithium niobate optical phase modulator, a Mach Zehnder interferometer (MZI) with a free spectral range of 75 GHz, and a 160 GHz to 260 GHz photomixer whose output is connected to a horn antenna. All of the optical devices and connections are polarization maintaining, and the photomixer was designed and fabricated at the CCLRC Rutherford Appleton Laboratory. The electrical path consists of a YIG synthesizer, operating in the frequency range 14-20 GHz, a frequency doubler, and a power amplifier connected to the RF port of the phase modulator. At the SMA on Mauna Kea, we incorporated the photonic LO into one element (Antenna 6) of a five antenna array for test observations of CO J=2-1 made towards the ultracompact HII region G138.295+1.555. Spectral features of comparable width occur on baselines with and without antenna 6, and noise increases with baseline length independent of antenna number. Continuum observations were also made toward the quasar 3c454.3 for a period of about one hour. In summary, the SMA has proven that the photonic local oscillator operates with adequate phase and frequency stability for radio-interferometry.

  11. Van der Pol and the history of relaxation oscillations: toward the emergence of a concept

    CERN Document Server

    Ginoux, Jean-Marc

    2014-01-01

    Relaxation oscillations are commonly associated with the name of Balthazar van der Pol via his eponymous paper (Philosophical Magazine, 1926) in which he apparently introduced this terminology to describe the nonlinear oscillations produced by self-sustained oscillating systems such as a triode circuit. Our aim is to investigate how relaxation oscillations were actually discovered. Browsing the literature from the late 19th century, we identified four self-oscillating systems in which relaxation oscillations have been observed: i) the series dynamo machine conducted by G\\'erard-Lescuyer (1880), ii) the musical arc discovered by Duddell (1901) and investigated by Blondel (1905), iii) the triode invented by de Forest (1907) and, iv) the multivibrator elaborated by Abraham and Bloch (1917). The differential equation describing such a self-oscillating system was proposed by Poincar\\'e for the musical arc (1908), by Janet for the series dynamo machine (1919), and by Blondel for the triode (1919). Once Janet (1919)...

  12. Identifying neuronal oscillations using rhythmicity

    NARCIS (Netherlands)

    Fransen, A.M.M.; Ede, F.L. van; Maris, E.G.G.

    2015-01-01

    Neuronal oscillations are a characteristic feature of neuronal activity and are typically investigated through measures of power and coherence. However, neither of these measures directly reflects the distinctive feature of oscillations: their rhythmicity. Rhythmicity is the extent to which future

  13. Volcanoes drive climate variability by emitting ozone weeks before eruptions, by forming lower stratospheric aerosols, by causing sustained ozone depletion, and by causing rapid changes in regional ozone concentrations affecting temperature and pressure differences driving atmospheric oscillations

    Science.gov (United States)

    Ward, P. L.

    2016-12-01

    March and April to 285 DU in October. Removing this seasonal change to calculate ozone anomaly and plotting against temperature anomaly, and climate oscillation indices such as NAM, NAO, ENSO, and SAM gives insight into the influence of volcanic eruptions on regional temperatures, pressures, winds, weather, and climate. WhyClimateChanges.com

  14. Building better oscillators using nonlinear dynamics and pattern ...

    Indian Academy of Sciences (India)

    2015-02-18

    Feb 18, 2015 ... Frequency and time references play an essential role in modern technology and in living systems. The precision of self-sustained oscillations is limited by the effects of noise, which becomes evermore important as the sizes of the devices become smaller. In this paper, we review our recent theoretical ...

  15. Relationship of AM to PM noise in selected RF oscillators.

    Science.gov (United States)

    Nelson, L M; Nelson, C W; Walls, F L

    1994-01-01

    We have studied the amplitude modulation (AM) and phase modulation (PM) noise in a number of 5 MHz and 100 MHz oscillators to provide a basis for developing models of the origin of AM noise. To adequately characterize the AM noise in high performance quartz oscillators, we found it necessary to use two-channel cross-correlation AM detection. In the quartz oscillators studied, the power spectral density (PSD) of the f(-1) and f(0) regions of AM noise is closely related to that of the PM noise. The major difference between different oscillators of the same design depends on the flicker noise performance of the resonator. We therefore propose that the f(-1) and f(0) regions of AM and PM noise arise from the same physical processes, probably originating in the sustaining amplifier.

  16. Expected quality factor of a simple tuned oscillator.

    Science.gov (United States)

    Tan, Kia Hock

    2011-05-01

    A positive feedback system oscillating under self-sustained mode is shown to have an extremely high gain. Modeled as one port, the expected Q is much higher than the loaded Q-factor of the resonator. With just thermal noise present, random phase/frequency deviation is linear. Centered about the oscillator frequency omega/(0), noise frequency on both sides is more amplified with decreasing separation distance. Ultimately, frequency pulling may result in synchronous locking with hysteresis, which occurs because a real oscillator displays a truncated limiting curve. Once locked onto a signal, smaller levels are ignored. A new approach to the design and characterization of a simple tuned oscillator is offered: According to the phenomenon of injection locking, there exists an expected quality factor relating the shape of the truncated limiting curve to an ideal curve. In this paper, synthesis and innovative analytical methods of academic interest are revealed: 1) application of the transducer loss method is revised to establish a new method for oscillator characterization; 2) a transparent method of normalizing a two-port network in the presence of white noise is developed; and 3) in quartz crystal controlled oscillators, characterization of the noise originating from an equivalent noise-resistance determined from parameter of the quartz crystal is proposed. It is shown that the two-port model can also be approximated on a one-port basis. In conclusion, a sample of closed-form estimation of expected Q-factor order of magnitude of piezoelectric resonator oscillators is calculated.

  17. Bimodal oscillations in nephron autoregulation

    DEFF Research Database (Denmark)

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

    2002-01-01

    The individual functional unit of the kidney (the nephron) displays oscillations in its pressure and flow regulation at two different time scales: fast oscillations associated with a myogenic dynamics of the afferent arteriole, and slower oscillations arising from a delay in the tubuloglomerular...

  18. Spectral linewidths of Josephson oscillators

    DEFF Research Database (Denmark)

    Salerno, M; Samuelsen, Mogens Rugholm; Yulin, AV

    2001-01-01

    We show that the linewidth of a Josephson flux-flow oscillator has the same functional dependence on temperature, static, and dynamic resistances as the ones of Josephson single-fluxon oscillators and small Josephson junctions. This suggests a universal formula for the linewidth of Josephson...... oscillators....

  19. Nonlinear (Anharmonic Casimir Oscillator

    Directory of Open Access Journals (Sweden)

    Habibollah Razmi

    2011-01-01

    Full Text Available We want to study the dynamics of a simple linear harmonic micro spring which is under the influence of the quantum Casimir force/pressure and thus behaves as a (an nonlinear (anharmonic Casimir oscillator. Generally, the equation of motion of this nonlinear micromechanical Casimir oscillator has no exact solvable (analytical solution and the turning point(s of the system has (have no fixed position(s; however, for particular values of the stiffness of the micro spring and at appropriately well-chosen distance scales and conditions, there is (are approximately sinusoidal solution(s for the problem (the variable turning points are collected in a very small interval of positions. This, as a simple and elementary plan, may be useful in controlling the Casimir stiction problem in micromechanical devices.

  20. Entanglement in neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-03-15

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

  1. Acoustics waves and oscillations

    CERN Document Server

    Sen, S.N.

    2013-01-01

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

  2. Convection and stellar oscillations

    DEFF Research Database (Denmark)

    Aarslev, Magnus Johan

    2017-01-01

    of stars. For stars like the sun, energy transport in the outer layers occurs mainly through turbulent convection. Here, pressure mode oscillations are essentially propagating sound waves, whose properties can be altered by interaction with the turbulent motion of the gas. This has always been a problem...... for asteroseismology, because of the challenges inherent in modelling turbulent convection in 1D stellar models. As a result of oversimplifying the physics near the surface, theoretical calculations systematically overestimate the oscillation frequencies. This has become known as the asteroseismic surface effect. Due...... to lacking better options, this frequency difference is typically corrected for with ad-hoc formulae. The topic of this thesis is the improvement of 1D stellar convection models and the effects this has on asteroseismic properties. The source of improvements is 3D simulations of radiation...

  3. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

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

    2007-01-01

    A proprioceptive stimulus consisting of a weight change of a handheld load has recently been shown to elicit an evoked potential. Previously, somatosensory gamma oscillations have only been evoked by electrical stimuli. We conjectured that a natural proprioceptive stimulus also would be able...... 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...... contralateral to stimulus side and additionally an unexpected 20 Hz activity was observed slightly lateralized in the frontal central region. The gamma phase locking may be a manifestation of early somatosensory feature integration. The analyses suggest that the high frequency activity consists of two distinct...

  4. Neutrino Masses and Oscillations

    CERN Multimedia

    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.

  5. Decay of oscillating universes

    Science.gov (United States)

    Mithani, Audrey Todhunter

    2016-08-01

    It has been suggested by Ellis et al that the universe could be eternal in the past, without beginning. In their model, the "emergent universe'' exists forever in the past, in an "eternal'' phase before inflation begins. We will show that in general, such an "eternal'' phase is not possible, because of an instability due to quantum tunneling. One candidate model, the "simple harmonic universe'' has been shown by Graham et al to be perturbatively stable; we find that it is unstable with respect to quantum tunneling. We also investigate the stability of a distinct oscillating model in loop quantum cosmology with respect to small perturbations and to quantum collapse. We find that the model has perturbatively stable and unstable solutions, with both types of solutions occupying significant regions of the parameter space. All solutions are unstable with respect to collapse by quantum tunneling to zero size. In addition, we investigate the effect of vacuum corrections, due to the trace anomaly and the Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. Finally, we determine the decay rate of the oscillating universe. Although the wave function of the universe lacks explicit time dependence in canonical quantum cosmology, time evolution may be present implicitly through the semiclassical superspace variables, which themselves depend on time in classical dynamics. Here, we apply this approach to the simple harmonic universe, by extending the model to include a massless, minimally coupled scalar field φ which has little effect on the dynamics but can play the role of a "clock''.

  6. Oscillating stagnation point flow

    Science.gov (United States)

    Grosch, C. E.; Salwen, H.

    1982-01-01

    A solution of the Navier-Stokes equations is given for an incompressible stagnation point flow whose magnitude oscillates in time about a constant, non-zero, value (an unsteady Hiemenz flow). Analytic approximations to the solution in the low and high frequency limits are given and compared with the results of numerical integrations. The application of these results to one aspect of the boundary layer receptivity problem is also discussed.

  7. Oscillations in the Umbral Atmosphere

    Science.gov (United States)

    Brynildsen, N.; Maltby, P.; Foley, C. R.; Fredvik, T.; Kjeldseth-Moe, O.

    2004-06-01

    The results of simultaneous observations of oscillations in the chromosphere, transition region, and corona above nine sunspots are presented. The data are obtained through coordinated observing with the Solar and Heliospheric Observatory — SOHO and the Transition Region And Coronal Explorer — TRACE. Oscillations are detected above each umbra. The power spectra show one dominant frequency corresponding to a period close to 3 min. We show that the oscillations in the sunspot transition region can be modeled by upwardly propagating acoustic waves. In the corona the oscillations are limited to small regions that often coincide with the endpoints of sunspot coronal loops. Spectral observations show that oscillations in the corona contribute to the observed oscillations in the TRACE 171 Å channel observations. We show that a recent suggestion regarding a connection between sunspot plumes and 3-min oscillations conflicts with the observations.

  8. Relaxation damping in oscillating contacts.

    Science.gov (United States)

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

    2015-11-09

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

  9. Live Cell Imaging Reveals pH Oscillations in Saccharomyces cerevisiae During Metabolic Transitions.

    Science.gov (United States)

    Dodd, Benjamin J T; Kralj, Joel M

    2017-10-24

    Addition of glucose to starved Saccharomyces cerevisiae initiates collective NADH dynamics termed glycolytic oscillations. Numerous questions remain about the extent to which single cells can oscillate, if oscillations occur in natural conditions, and potential physiological consequences of oscillations. In this paper, we report sustained glycolytic oscillations in single cells without the need for cyanide. Glucose addition to immobilized cells induced pH oscillations that could be imaged with fluorescent sensors. A population of cells had oscillations that were heterogeneous in frequency, start time, stop time, duration and amplitude. These changes in cytoplasmic pH were necessary and sufficient to drive changes in NADH. Oscillators had lower mitochondrial membrane potentials and budded more slowly than non-oscillators. We also uncovered a new type of oscillation during recovery from H2O2 challenge. Our data show that pH in S. cerevisiae changes over several time scales, and that imaging pH offers a new way to measure glycolytic oscillations on individual cells.

  10. Glucose Oscillations Can Activate an Endogenous Oscillator in Pancreatic Islets.

    Directory of Open Access Journals (Sweden)

    Joseph P McKenna

    2016-10-01

    Full Text Available Pancreatic islets manage elevations in blood glucose level by secreting insulin into the bloodstream in a pulsatile manner. Pulsatile insulin secretion is governed by islet oscillations such as bursting electrical activity and periodic Ca2+ entry in β-cells. In this report, we demonstrate that although islet oscillations are lost by fixing a glucose stimulus at a high concentration, they may be recovered by subsequently converting the glucose stimulus to a sinusoidal wave. We predict with mathematical modeling that the sinusoidal glucose signal's ability to recover islet oscillations depends on its amplitude and period, and we confirm our predictions by conducting experiments with islets using a microfluidics platform. Our results suggest a mechanism whereby oscillatory blood glucose levels recruit non-oscillating islets to enhance pulsatile insulin output from the pancreas. Our results also provide support for the main hypothesis of the Dual Oscillator Model, that a glycolytic oscillator endogenous to islet β-cells drives pulsatile insulin secretion.

  11. Sustainable agriculture

    National Research Council Canada - National Science Library

    Lichtfouse, Eric

    2009-01-01

    ... : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : : 9 Part I CLIMATE CHANGE Soils and Sustainable Agriculture: A Review : : : : : : : : : : : : : : : : : : : : : : : : : : Rattan Lal 15 Soils and Food Sufficiency...

  12. Sustainable Marketing

    NARCIS (Netherlands)

    Dam, van Y.K.

    2017-01-01

    In this article, three different conceptions of sustainable marketing are discussed and compared. These different conceptions are referred to as social, green, and critical sustainable marketing. Social sustainable marketing follows the logic of demand-driven marketing management and places the

  13. Synchronization of Tubular Pressure Oscillations in Interacting Nephrons

    DEFF Research Database (Denmark)

    Sosnovtseva, Olga; Postnov, D.E.; Mosekilde, Erik

    2003-01-01

    The pressure and flow regulation in the individual functional unit of the kidney (the nephron) tends to operate in an unstable regime. For normal rats, the regulation displays regular self-sustained oscillations, but for rats with high blood pressure the oscillations become chaotic. We explain....... For spontaneously hypertensive rats, indications of chaotic phase synchronization are found. Accounting for a hermodynamics as well as for a vascular coupling between nephrons that share a common interlobular artery, we present a model of the interaction of the pressure and flow regulations between adjacent...

  14. 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....

  15. 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...... diffusive coupling that gives rise to wave dynamics and via fast changes in membrane potential that propagate almost instantly over significant distances. The model reproduces the basic calcium dynamics of the vascular smooth muscle cell: calcium waves which upon increased activity of cGMP-sensitive calcium...

  16. Oscillations in nonlinear systems

    CERN Document Server

    Hale, Jack K

    2015-01-01

    By focusing on ordinary differential equations that contain a small parameter, this concise graduate-level introduction to the theory of nonlinear oscillations provides a unified approach to obtaining periodic solutions to nonautonomous and autonomous differential equations. It also indicates key relationships with other related procedures and probes the consequences of the methods of averaging and integral manifolds.Part I of the text features introductory material, including discussions of matrices, linear systems of differential equations, and stability of solutions of nonlinear systems. Pa

  17. Brain Oscillations, Hypnosis, and Hypnotizability.

    Science.gov (United States)

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

    2015-01-01

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

  18. 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 individu...... oscillators. The spectrum of the Lyapunov exponents (LE) have been calculated versus the coefficient k. For weakly coupled oscillators there are two positive LE indicating hyperchaotic behaviour of the overall system.......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...

  19. 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.

  20. A Matterwave Transistor Oscillator

    CERN Document Server

    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, ...

  1. Heat exchanger with oscillating flow

    Science.gov (United States)

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

    1993-01-01

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

  2. 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....

  3. 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...

  4. Sustainable Disruptions

    DEFF Research Database (Denmark)

    Friis, Silje Alberthe Kamille; Kjær, Lykke Bloch

    2016-01-01

    Since 2012 the Sustainable Disruptions (SD) project at the Laboratory for Sustainability at Design School Kolding (DK) has developed and tested a set of design thinking tools, specifically targeting the barriers to economically, socially, and environmentally sustainable business development....... The tools have been applied in practice in collaboration with 11 small and medium sized companies (SMEs). The study investigates these approaches to further understand how design thinking can contribute to sustainable transition in a business context. The study and the findings are relevant to organizations...... invested in the issue of sustainable business development, in particular the leaders and employees of SMEs, but also to design education seeking new ways to consciously handle and teach the complexity inherent in sustainable transformation. Findings indicate that the SD design thinking approach contributes...

  5. Computational sustainability

    CERN Document Server

    Kersting, Kristian; Morik, Katharina

    2016-01-01

    The book at hand gives an overview of the state of the art research in Computational Sustainability as well as case studies of different application scenarios. This covers topics such as renewable energy supply, energy storage and e-mobility, efficiency in data centers and networks, sustainable food and water supply, sustainable health, industrial production and quality, etc. The book describes computational methods and possible application scenarios.

  6. 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.

  7. Sustainable transformation

    DEFF Research Database (Denmark)

    Andersen, Nicolai Bo

    This paper is about sustainable transformation with a particular focus on listed buildings. It is based on the notion that sustainability is not just a question of energy conditions, but also about the building being robust. Robust architecture means that the building can be maintained and rebuilt...... theoretical lenses. It is proposed that three parameters concerning the ꞌtransformabilityꞌ of the building can contribute to a more nuanced understanding of sustainable transformation: technical aspects, programmatic requirements and narrative value. It is proposed that the concept of ꞌsustainable...

  8. 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...... equations, PSPICE simulations and hardware experiments. The Lyapunov exponents are presented to confirm hyperchaotic mode of the oscillations....

  9. 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...

  10. Energy Conservative Limit Cycle Oscillations

    NARCIS (Netherlands)

    Stramigioli, Stefano; van Dijk, Michel

    This paper shows how globally attractive limit cycle oscillations can be induced in a system with a nonlinear feedback element. Based on the same principle as the Van der Pol oscillator, the feedback behaves as a negative damping for low velocities but as an ordinary damper for high velocities. This

  11. Mechanical Parametric Oscillations and Waves

    Science.gov (United States)

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

    2013-01-01

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

  12. Augmenting cognition by neuronal oscillations

    NARCIS (Netherlands)

    Horschig, J.M.; Zumer, J.; Bahramisharif, A.

    2014-01-01

    Cortical oscillations have been shown to represent fundamental functions of a working brain, e.g., communication, stimulus binding, error monitoring, and inhibition, and are directly linked to behavior. Recent studies intervening with these oscillations have demonstrated effective modulation of both

  13. Tomography on f-oscillators

    Science.gov (United States)

    Dudinets, I. V.; Man’ko, V. I.; Marmo, G.; Zaccaria, F.

    2017-11-01

    Symplectic tomographies of classical and quantum states are shortly reviewed. The concept of nonlinear f-oscillators and their properties are recalled. The tomographic probability representations of oscillator coherent states and the problem of entanglement are then discussed. The entanglement of even and odd f-coherent states is evaluated by the linear entropy.

  14. Quasi Periodic Oscillations in Blazars

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 35; Issue 3. Quasi Periodic Oscillations in Blazars ... Here we report our recent discoveries of Quasi-Periodic Oscillations (QPOs) in blazars time series data in X-ray and optical electromagnetic bands. Any such detection can give important ...

  15. Prospects for Neutrino Oscillation Physics

    Directory of Open Access Journals (Sweden)

    Silvia Pascoli

    2013-01-01

    Full Text Available Recently the last unknown lepton mixing angle θ 13 has been determined to be relatively large, not too far from its previous upper bound. This opens exciting possibilities for upcoming neutrino oscillation experiments towards addressing fundamental questions, among them the type of the neutrino mass hierarchy and the search for CP violation in the lepton sector. In this paper we review the phenomenology of neutrino oscillations, focusing on subleading effects, which will be the key towards these goals. Starting from a discussion of the present determination of three-flavour oscillation parameters, we give an outlook on the potential of near-term oscillation physics as well as on the long-term program towards possible future precision oscillation facilities. We discuss accelerator-driven long-baseline experiments as well as nonaccelerator possibilities from atmospheric and reactor neutrinos.

  16. 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....

  17. Sustained small oscillations in nonlinear control systems. [launch vehicle dynamics

    Science.gov (United States)

    George, J. H.; Gunderson, R. W.; Hahn, H.

    1975-01-01

    Some results of bifurcation theory were used to study the existence of small-amplitude periodic behavior in launch vehicle dynamics, assuming that nonlinearity exists as a cubic term in the rudder response. The analysis follows closely Sattinger's (1973) approach to the theory of periodic bifurcations. The conditions under which a bifurcating branch of orbitally stable periodic solutions will exist are determined. It is shown that in more complicated cases, the conditions under which the system matrix has a pair of simple purely imaginary eigenvalues can be determined with the aid of linear stability techniques.

  18. Calcium modulation of exocytosis-linked plasma membrane potential oscillations in INS-1 832/13 cells.

    Science.gov (United States)

    Gerencser, Akos A; Mulder, Hindrik; Nicholls, David G

    2015-10-01

    In the presence of high glucose or pyruvate, INS-1 832/13 insulinoma cells undergo stochastic oscillations in plasma membrane potential (Δψp) leading to associated fluctuations in cytosolic free Ca(2+) concentration ([Ca(2+)]c). Oscillations are not driven by upstream metabolic fluctuations, but rather by autonomous ionic mechanisms, the details of which are unclear. We have investigated the nature of the oscillator, with simultaneous fluorescence monitoring of Δψp, [Ca(2+)]c and exocytosis at single-cell resolution, combined with analysis of the occurrence, frequency and amplitude of Δψp oscillations. Oscillations were closely coupled to exocytosis, indicated by coincident synaptopHluorin fluorescence enhancement. L-type Ca(2+) channel inhibitors enhanced Δψp and [Ca(2+)]c oscillation frequency in the presence of pyruvate, but abolished the sustained [Ca(2+)]c response following KCl depolarization. The L-type Ca(2+) channel inhibitor isradipine did not inhibit oscillation-linked exocytosis. The T-type Ca(2+) channel inhibitor NNC 55-0396 inhibited Δψp and [Ca(2+)]c oscillations, implying that T-type Ca(2+) channels trigger oscillations and consequent exocytosis. Since distinct ion channels operate in oscillating and non-oscillating cells, quantitative analysis of Δψp and [Ca(2+)]c oscillations in a β-cell population may help to improve our understanding of the link between metabolism and insulin secretion. © 2015 Authors; published by Portland Press Limited.

  19. Sustainable Transportation

    DEFF Research Database (Denmark)

    Hall, Ralph P.; Gudmundsson, Henrik; Marsden, Greg

    2014-01-01

    that relate to the construction and maintenance of transportation infrastructure and the operation or use of the different transportation modes. The concept of sustainable transportation emerged in response to these concerns as part of the broader notion of sustainable development. Given the transportation...

  20. Sustaining dairy

    NARCIS (Netherlands)

    Villarreal Herrera, Georgina

    2017-01-01

    Dairy in Europe has undergone many changes in the last few years—the abolition of milk production quotas being a fundamental one. This study explores these changes in relation to the sustained social and environmental viability of the sector and how dairy processors' sustainability

  1. Sustainable Universities

    DEFF Research Database (Denmark)

    Grindsted, Thomas Skou

    2011-01-01

    . Declarations tend to have impact on three trends. Firstly, there is emerging international consensus on the university’s role and function in relation to sustainable development; secondly, the emergence of national legislation, and thirdly, an emerging international competition to be leader in sustainable...... campus performance....

  2. Sustainable Transition

    DEFF Research Database (Denmark)

    Hansen, Ole Erik; Søndergård, Bent

    2014-01-01

    of agendas/vision, technologies, actors and institutions in the emergent design of an urban mobility system based on an electric car sharing system. Why. Designing for sustainability is a fundamental challenge for future design practices; designers have to obtain an ability to contribute to sustainable...

  3. Sustainable Learning

    Science.gov (United States)

    Cadwell, Louise; Dillon, Robert

    2011-01-01

    Green schools have moved into a new era that focuses on building a culture of sustainability in every aspect of learning in schools. In the early stages of sustainability education, the focus was on recycling and turning off the lights. Now, students and adults together are moving into the areas of advocacy and action that are based on a deep…

  4. Noise and robustness in the cyanobacterial circadian oscillator

    Science.gov (United States)

    Lubensky, David

    2010-03-01

    Like humans and most higher animals, photosynthetic cyanobacteria possess an autonomous 24-hour circadian clock that allows them to anticipate daily changes in their environment. This oscillator is known to be extremely stable, with a correlation time on the order of 100 days in a single, isolated cell, even in the absence of any entraining signals from the environment. The origin of such remarkable robustness, however, remains mysterious. Here, we present a stochastic model of the biochemical circuitry underlying the clock, including both transcriptional feedback and the post-translational phosphorylation cycle that is thought to be the core oscillator. We find that the phosphorylation oscillator in isolation is highly resistant to the intrinsic noise associated with molecular discreteness, but that a growing, dividing cell is a considerably more challenging environment in which to sustain stable oscillations. We suggest that coupling the phosphorylation cycle to a clock based on delayed negative transcriptional feedback may substantially increase the robustness of both oscillators and detail how this enhancement comes about.

  5. Bimodal oscillations in nephron autoregulation

    DEFF Research Database (Denmark)

    Sosnovtseva, Olga; Pavlov, A N; Mosekilde, E

    2002-01-01

    The individual functional unit of the kidney (the nephron) displays oscillations in its pressure and flow regulation at two different time scales: fast oscillations associated with a myogenic dynamics of the afferent arteriole, and slower oscillations arising from a delay in the tubuloglomerular...... feedback. We investigate the intra- and internephron entrainment of the two time scales. In addition to full synchronization, both wavelet analyses of experimental data and numerical simulations reveal a partial entrainment in which neighboring nephrons attain a state of chaotic synchronization...

  6. Collective oscillations in a plasma

    CERN Document Server

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

    2013-01-01

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

  7. Turbulent drag reduction through oscillating discs

    CERN Document Server

    Wise, Daniel J

    2014-01-01

    The changes of a turbulent channel flow subjected to oscillations of wall flush-mounted rigid discs are studied by means of direct numerical simulations. The Reynolds number is $R_\\tau$=$180$, based on the friction velocity of the stationary-wall case and the half channel height. The primary effect of the wall forcing is the sustained reduction of wall-shear stress, which reaches a maximum of 20%. A parametric study on the disc diameter, maximum tip velocity, and oscillation period is presented, with the aim to identify the optimal parameters which guarantee maximum drag reduction and maximum net energy saving, computed by taking into account the power spent to actuate the discs. This may be positive and reaches 6%. The Rosenblat viscous pump flow is used to predict the power spent for disc motion in the turbulent channel flow and to estimate localized and transient regions over the disc surface subjected to the turbulent regenerative braking effect, for which the wall turbulence exerts work on the discs. The...

  8. Model of stochastic self-oscillation in Gunn diode oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Bocharov, E.P.; Korostelev, G.N.; Khripunov, M.V.

    1987-07-01

    The applicability of the two-mode nonlinear model of decay stochasticity for explanation of the transition from monochromatic self-oscillation to developed stochasticity in the Gunn diode oscillator is demonstrated. Numerical realizations of the basic regimes corresponding to various cases of consideration of the weak nonlinearity of the falling portion of the current-voltage characteristic are presented. A comparative analysis of calculation results of time realizations and experimentally observed oscillograms of stochastic regimes is performed.

  9. Oscillations in Mathematical Biology

    CERN Document Server

    1983-01-01

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

  10. Coherence of biochemical oscillations is bounded by driving force and network topology

    Science.gov (United States)

    Barato, Andre C.; Seifert, Udo

    2017-06-01

    Biochemical oscillations are prevalent in living organisms. Systems with a small number of constituents cannot sustain coherent oscillations for an indefinite time because of fluctuations in the period of oscillation. We show that the number of coherent oscillations that quantifies the precision of the oscillator is universally bounded by the thermodynamic force that drives the system out of equilibrium and by the topology of the underlying biochemical network of states. Our results are valid for arbitrary Markov processes, which are commonly used to model biochemical reactions. We apply our results to a model for a single KaiC protein and to an activator-inhibitor model that consists of several molecules. From a mathematical perspective, based on strong numerical evidence, we conjecture a universal constraint relating the imaginary and real parts of the first nontrivial eigenvalue of a stochastic matrix.

  11. Strong nonlinear oscillators analytical solutions

    CERN Document Server

    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.

  12. Long period oscillations in sunspots

    Science.gov (United States)

    Chorley, N.; Hnat, B.; Nakariakov, V. M.; Inglis, A. R.; Bakunina, I. A.

    2010-04-01

    Long period oscillations of the gyroresonant emission from sunspot atmospheres are studied. Time series data generated from the sequences of images obtained by the Nobeyama Radioheliograph operating at a frequency of 17 GHz for three sunspots have been analysed and are found to contain significant periods in the range of several tens of minutes. Wavelet analysis shows that these periods are persistent throughout the observation periods. The presence of the oscillations is confirmed by several methods (periodogram, wavelets, Fisher randomisation and empirical mode decomposition). Spatial analysis using the techniques of period, power, correlation and time lag mapping reveals regions of enhanced oscillatory power in the umbral regions. Also seen are two regions of coherent oscillation of about 25 pixels in size, that oscillate in anti-phase with each other. Possible interpretation of the observed periodicities is discussed, in terms of the shallow sunspot model and the leakage of the solar g-modes.

  13. Sustainable consumption

    DEFF Research Database (Denmark)

    Prothero, Andrea; Dobscha, Susan; Freund, Jim

    2011-01-01

    This essay explores sustainable consumption and considers possible roles for marketing and consumer researchers and public policy makers in addressing the many sustainability challenges that pervade our planet. Future research approaches to this interdisciplinary topic need to be comprehensive...... and systematic and will benefit from a variety of different perspectives. There are a number of opportunities for future research, and three areas are explored in detail. First, the essay considers the inconsistency between the attitudes and behaviors of consumers with respect to sustainability; next, the agenda...... is broadened to explore the role of individual citizens in society; and finally, a macro institutional approach to fostering sustainability is explored. Each of these areas is examined in detail and possible research avenues and public policy initiatives are considered within each of these separate...

  14. Stabilizing Sustainability

    DEFF Research Database (Denmark)

    Reitan Andersen, Kirsti

    The publication of the Brundtland Report in 1987 put the topic of sustainable development on the political and corporate agenda. Defining sustainable development as “a development that meets the needs of the future without compromising the ability of future generations to meet their own needs......” (WCED, 1987, p. 43), the Report also put a positive spin on the issue of sustainability by upholding capitalist beliefs in the possibility of infinite growth in a world of finite resources. While growth has delivered benefits, however, it has done so unequally and unsustainably. This thesis focuses...... on the textile and fashion industry, one of the world’s most polluting industries and an industry to some degree notorious for leading the ‘race to the bottom’ in global labour standards. Despite being faced with increasing demands to practise sustainability, most textile and fashion companies continue to fail...

  15. Sustainability reporting

    NARCIS (Netherlands)

    Kolk, A.

    2005-01-01

    This article gives an overview of developments in sustainability (also sometimes labelled corporate social responsibility) reporting. The article will first briefly indicate how accountability on social and environmental issues started, already in the 1970s when social reports were published.

  16. Sustainable Cities

    DEFF Research Database (Denmark)

    Georg, Susse; Garza de Linde, Gabriela Lucía

    Judging from the number of communities and cities striving or claiming to be sustainable and how often eco-development is invoked as the means for urban regeneration, it appears that sustainable and eco-development have become “the leading paradigm within urban development” (Whitehead 2003......), urban design competitions are understudied mechanisms for bringing about field level changes. Drawing on actor network theory, this paper examines how urban design competitions may bring about changes within the professional field through the use of intermediaries such as a sustainable planning....../assessment tool. The context for our study is urban regeneration in one Danish city, which had been suffering from industrial decline and which is currently investing in establishing a “sustainable city”. Based on this case study we explore how the insights and inspiration evoked in working with the tool...

  17. Sustainable responsibilities?

    DEFF Research Database (Denmark)

    Lystbæk, Christian Tang

    2015-01-01

    This working paper analyzes the conceptions of corporate responsibility for sustainable development in EU policies on CSR. The notion of corporate responsibility has until recently been limited to economical and legal responsibilities. Based on this narrow conception of corporate responsibility.......e. a combination of destruction and construction, this chapter will deconstruct conceptions of responsibility for sustainable development in these EU documents on CSR. A deconstructive conceptual analysis involves destructing dominant interpretations of a text and allowing for constructions of alternative...... such as sustainability actually means, but on what the concept says and does not say. A deconstructive analysis of EU policies on CSR, then, pinpoints that such policies are sites of conceptual struggles. This kind of analysis is suitable for studying conceptions of corporate responsibility for sustainable development...

  18. Agriculture: Sustainability

    Science.gov (United States)

    Sustainability creates and maintains the conditions under which humans and nature can exist in productive harmony, that permit fulfilling the food, feed, and fiber needs of our country and the social, economic and other requirements.

  19. Building a Synthetic Transcriptional Oscillator.

    Science.gov (United States)

    Schwarz-Schilling, Matthaeus; Kim, Jongmin; Cuba, Christian; Weitz, Maximilian; Franco, Elisa; Simmel, Friedrich C

    2016-01-01

    Reaction circuits mimicking genetic oscillators can be realized with synthetic, switchable DNA genes (so-called genelets), and two enzymes only, an RNA polymerase and a ribonuclease. The oscillatory behavior of the genelets is driven by the periodic production and degradation of RNA effector molecules. Here, we describe the preparation, assembly, and testing of a synthetic, transcriptional two-node negative-feedback oscillator, whose dynamics can be followed in real-time by fluorescence read-out.

  20. An Oscillating Magnet Watt Balance

    OpenAIRE

    Ahmedov, H.

    2015-01-01

    We establish the principles for a new generation of simplified and accurate watt balances in which an oscillating magnet generates Faraday's voltage in a stationary coil. A force measuring system and a mechanism providing vertical movements of the magnet are completely independent in an oscillating magnet watt balance. This remarkable feature allows to establish the link between the Planck constant and a macroscopic mass by a one single experiment. Weak dependence on variations of environment...

  1. Sustainable finance

    OpenAIRE

    Boersma-de Jong, Margreet F.

    2012-01-01

    Presentation for Springschool of Strategy, University of Groningen, 10 October 2012. The role of CSR is to stimulate ethical behaviour, and as a result, mutual trust in society. Advantage of CSR for the company and the evolution of CSR. From CSR to Sustainable Finance: how does CSR influence Sustainable Business Administration & Management Accounting, Financial Leadership and what is the importance of CSR in the financial sector

  2. SUSTAINABLE TRANSPORTATION

    Directory of Open Access Journals (Sweden)

    Linda STEG

    2007-01-01

    Full Text Available This paper discusses possible contributions of psychologists to sustainable transportation. It is argued that in order to reach sustainable transportation, among others, behaviour changes of individual car users are needed. As transport policies will be more effective if they target important antecedents of travel behaviour, first, factors influencing such behaviour are discussed. It is argued that car use is very attractive and sometimes even necessary for many different reasons. This implies that a combination of policies is called for, each targeting different factors that support car use and hinder the use of more sustainable modes of transport. Next, the paper elaborates on policy strategies that may be employed to achieve sustainable transportation by changing car use. Increasing the attractiveness of sustainable transport modes by means of pull measures seems not sufficient to reduce the level of car use. Besides, car use should be made less attractive by means of push measures to force drivers to reconsider their travel behaviour. The acceptability of such policies may be increased by clearly communicating the aim of these policies, and the expected positive consequences (e.g., less congestion, improved environmental quality. Moreover, possible negative effects for individual freedom may be compensated by implementing additional policies aimed at facilitating the use of sustainable transport modes.

  3. Modeling nonlinearities in MEMS oscillators.

    Science.gov (United States)

    Agrawal, Deepak K; Woodhouse, Jim; Seshia, Ashwin A

    2013-08-01

    We present a mathematical model of a microelectromechanical system (MEMS) oscillator that integrates the nonlinearities of the MEMS resonator and the oscillator circuitry in a single numerical modeling environment. This is achieved by transforming the conventional nonlinear mechanical model into the electrical domain while simultaneously considering the prominent nonlinearities of the resonator. The proposed nonlinear electrical model is validated by comparing the simulated amplitude-frequency response with measurements on an open-loop electrically addressed flexural silicon MEMS resonator driven to large motional amplitudes. Next, the essential nonlinearities in the oscillator circuit are investigated and a mathematical model of a MEMS oscillator is proposed that integrates the nonlinearities of the resonator. The concept is illustrated for MEMS transimpedance-amplifier- based square-wave and sine-wave oscillators. Closed-form expressions of steady-state output power and output frequency are derived for both oscillator models and compared with experimental and simulation results, with a good match in the predicted trends in all three cases.

  4. Sustainable markets for sustainable energy

    Energy Technology Data Exchange (ETDEWEB)

    Millan, J.; Smyser, C.

    1997-12-01

    The author discusses how the Inter-American Development Bank (IDB) is involved in sustainable energy development. It presently has 50 loans and grants for non conventional renewable energy projects and ten grants for efficiency programs for $600 and $17 million respectively, representing 100 MW of power. The IDB is concerned with how to create a sustainable market for sustainable energy projects. The IDB is trying to work with government, private sector, NGOs, trading allies, credit sources, and regulators to find proper roles for such projects. He discusses how the IDB is working to expand its vision and objectives in renewable energy projects in Central and South America.

  5. A modified hybrid Van der Pol-Duffing-Rayleigh oscillator for modelling the lateral walking force on a rigid floor

    Science.gov (United States)

    Kumar, Prakash; Kumar, Anil; Erlicher, Silvano

    2017-11-01

    The paper proposes a single degree of freedom oscillator in order to accurately represent the lateral force acting on a rigid floor due to human walking. As a pedestrian produces itself the energy required to maintain its motion, it can be modelled as a self-sustained oscillator that is able to produce: (i) self-sustained motion; (ii) a lateral periodic force signal; and (iii) a stable limit cycle. The proposed oscillator is a modification of hybrid Van der Pol-Duffing-Rayleigh oscillator, by introducing an additional nonlinear hardening term. Stability analysis of the proposed oscillator has been performed by using the energy balance method and the Lindstedt-Poincare perturbation technique. Model parameters were identified from the experimental force signals of ten pedestrians using the least squares identification technique. The experimental and the model generated lateral forces show a good agreement.

  6. On the nonlinear modeling of ring oscillators

    KAUST Repository

    Elwakil, Ahmed S.

    2009-06-01

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

  7. 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...

  8. On the mechanism of oscillations in neutrophils

    DEFF Research Database (Denmark)

    Brasen, Jens Christian; Barington, Torben; Olsen, Lars Folke

    2010-01-01

    of the external glucose concentration and the oscillations in H(2)O(2) production are 180 degrees out of phase with the oscillations in NAD(P)H. Cytochalasin B blocked the oscillations in shape and size whereas it increased the period of the oscillations in H(2)O(2) production. 1- and 2-butanol also blocked...... the oscillations in shape and size, but only 1-butanol inhibited the oscillations in H(2)O(2) production. We conjecture that the oscillations are likely to be due to feedback regulations in the signal transduction cascade involving phosphoinositide 3-kinases (PI3K). We have tested this using a simple mathematical......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...

  9. Universal, computer facilitated, steady state oscillator, closed loop analysis theory and some applications to precision oscillators

    Science.gov (United States)

    Parzen, Benjamin

    1992-01-01

    The theory of oscillator analysis in the immittance domain should be read in conjunction with the additional theory presented here. The combined theory enables the computer simulation of the steady state oscillator. The simulation makes the calculation of the oscillator total steady state performance practical, including noise at all oscillator locations. Some specific precision oscillators are analyzed.

  10. Intergroup Conflict Self-Perpetuates via Meaning: Exposure to Intergroup Conflict Increases Meaning and Fuels a Desire for Further Conflict.

    Science.gov (United States)

    Rovenpor, Daniel R; O'Brien, Thomas C; Roblain, Antoine; De Guissmé, Laura; Chekroun, Peggy; Leidner, Bernhard

    2017-09-25

    We investigated whether violent conflict provides individuals with a sense of meaning that they are hesitant to let go of, thus contributing to the perpetuation of intergroup conflict. Across a wide variety of contexts, we found that making intergroup conflict salient increased the meaning people found in conflict and, in turn, increased support for conflict-perpetuating beliefs, ideologies, policies, and behaviors. These effects were detected among participants exposed to reminders of intergroup conflict (the American Revolutionary War and the U.S.-led campaign against ISIS; Studies 1A and 1B), participants living through actual intergroup conflict (the 2014 Israel-Gaza war; Study 2), and participants who perceived actual intergroup conflicts to be larger versus smaller in scope (the November 2015 Paris attacks; Studies 3 and 4). We also found that directly manipulating the perceived meaning in conflict (in the context of the 2014 NYC "hatchet attack"; Study 5) led to greater perceived meaning in life in general and thereby greater support for conflict escalation. Together, these findings suggest that intergroup conflict can serve as a source of meaning that people are motivated to hold on to. We discuss our findings in the context of the meaning making and threat compensation literatures, and consider their implications for perspectives on conflict escalation and resolution. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

  11. Working to Design: The Self-Perpetuating Ideology of Rock or ... ‘The New Bob Dylan’

    Directory of Open Access Journals (Sweden)

    John Scannell

    2011-08-01

    Full Text Available This premise of this article is that music and the writing process have no inherent kinship, and that the often ill-conceived merger of these activities as the “music writing” process, is generally destined for failure. That is because writing about music subsumes its affective power into a foreign modality; it is captured and rendered into the printed word, made to signify, made to represent something, where that something is generally resolved within the presuppositions of the writers’ often-limited referential framework. At the heart of the matter is that writing about music often does not attempt to capture the affective processes that inspired creation in the first place, and in this respect, the paper argues that it may be more appropriate for the music writer/journalist to respond in kind, or as Deleuze and Guattari might say, that the music writing process should pursue a ‘becoming-music’ itself. For rather than subjecting music to the realm of representation, or subsuming its creative power within the realm of opinion and cliché, the writer should instead be concerned with harnessing and re-channelling those forces of sensation or affect that gave rise to it in the first place, and which might, in turn, inspire a literary creativity that is commensurate to the power of the music at hand.

  12. A self-perpetuating repressive state of a viral replication protein blocks superinfection by the same virus.

    Directory of Open Access Journals (Sweden)

    Xiao-Feng Zhang

    2017-03-01

    Full Text Available Diverse animal and plant viruses block the re-infection of host cells by the same or highly similar viruses through superinfection exclusion (SIE, a widely observed, yet poorly understood phenomenon. Here we demonstrate that SIE of turnip crinkle virus (TCV is exclusively determined by p28, one of the two replication proteins encoded by this virus. p28 expressed from a TCV replicon exerts strong SIE to a different TCV replicon. Transiently expressed p28, delivered simultaneously with, or ahead of, a TCV replicon, largely recapitulates this repressive activity. Interestingly, p28-mediated SIE is dramatically enhanced by C-terminally fused epitope tags or fluorescent proteins, but weakened by N-terminal modifications, and it inversely correlates with the ability of p28 to complement the replication of a p28-defective TCV replicon. Strikingly, p28 in SIE-positive cells forms large, mobile punctate inclusions that trans-aggregate a non-coalescing, SIE-defective, yet replication-competent p28 mutant. These results support a model postulating that TCV SIE is caused by the formation of multimeric p28 complexes capable of intercepting fresh p28 monomers translated from superinfector genomes, thereby abolishing superinfector replication. This model could prove to be applicable to other RNA viruses, and offer novel targets for antiviral therapy.

  13. Roundtabling Sustainability

    DEFF Research Database (Denmark)

    Ponte, Stefano

    2014-01-01

    The willingness of public authority to delegate social and environmental regulation to the private sector has varied from sector to sector, but has often led to the establishment of ‘voluntary’ standards and certifications on sustainability. Many of these have taken the form of ‘stewardship...... councils’ and ‘sustainability roundtables’ and have been designed around a set of institutional features seeking to establish legitimacy, fend off possible criticism, and ‘sell’ certifications to potential users. The concept of ‘roundtabling’ emphasizes the fitting a variety of commodity......-specific sustainability situations into a form that not only ‘hears more voices’ (as in ‘multi-stakeholder’), but also portrays to give them equal standing at the table of negotiations (roundtable), thus raising higher expectations on accountability, transparency and inclusiveness. In this article, I examine to what...

  14. Sustainability Evaluation.

    Science.gov (United States)

    Stichnothe, Heinz

    2017-03-17

    The long-term substitution of fossil resources can only be achieved through a bio-based economy, with biorefineries and bio-based products playing a major role. However, it is important to assess the implications of the transition to a bio-based economy. Life cycle-based sustainability assessment is probably the most suitable approach to quantify impacts and to identify trade-offs at multiple levels. The extended utilisation of biomass can cause land use change and affect food security of the most vulnerable people throughout the world. Although this is mainly a political issue and governments should be responsible, the responsibility is shifted to companies producing biofuels and other bio-based products. Organic wastes and lignocellulosic biomass are considered to be the preferred feedstock for the production of bio-based products. However, it is unlikely that a bio-based economy can rely only on organic wastes and lignocellulosic biomass.It is crucial to identify potential problems related to socio-economic and environmental issues. Currently there are many approaches to the sustainability of bio-based products, both quantitative and qualitative. However, results of different calculation methods are not necessarily comparable and can cause confusion among decision-makers, stakeholders and the public.Hence, a harmonised, globally agreed approach would be the best solution to secure sustainable biomass/biofuels/bio-based chemicals production and trade, and to avoid indirect effects (e.g. indirect land use change). However, there is still a long way to go.Generally, the selection of suitable indicators that serve the purpose of sustainability assessment is very context-specific. Therefore, it is recommended to use a flexible and modular approach that can be adapted to various purposes. A conceptual model for the selection of sustainability indicators is provided that facilitates identifying suitable sustainability indicators based on relevance and significance in a

  15. Synchronization-induced rhythmicity of circadian oscillators in the suprachiasmatic nucleus.

    Directory of Open Access Journals (Sweden)

    Samuel Bernard

    2007-04-01

    Full Text Available The suprachiasmatic nuclei (SCN host a robust, self-sustained circadian pacemaker that coordinates physiological rhythms with the daily changes in the environment. Neuronal clocks within the SCN form a heterogeneous network that must synchronize to maintain timekeeping activity. Coherent circadian output of the SCN tissue is established by intercellular signaling factors, such as vasointestinal polypeptide. It was recently shown that besides coordinating cells, the synchronization factors play a crucial role in the sustenance of intrinsic cellular rhythmicity. Disruption of intercellular signaling abolishes sustained rhythmicity in a majority of neurons and desynchronizes the remaining rhythmic neurons. Based on these observations, the authors propose a model for the synchronization of circadian oscillators that combines intracellular and intercellular dynamics at the single-cell level. The model is a heterogeneous network of circadian neuronal oscillators where individual oscillators are damped rather than self-sustained. The authors simulated different experimental conditions and found that: (1 in normal, constant conditions, coupled circadian oscillators quickly synchronize and produce a coherent output; (2 in large populations, such oscillators either synchronize or gradually lose rhythmicity, but do not run out of phase, demonstrating that rhythmicity and synchrony are codependent; (3 the number of oscillators and connectivity are important for these synchronization properties; (4 slow oscillators have a higher impact on the period in mixed populations; and (5 coupled circadian oscillators can be efficiently entrained by light-dark cycles. Based on these results, it is predicted that: (1 a majority of SCN neurons needs periodic synchronization signal to be rhythmic; (2 a small number of neurons or a low connectivity results in desynchrony; and (3 amplitudes and phases of neurons are negatively correlated. The authors conclude that to

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

    DEFF Research Database (Denmark)

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

    2007-01-01

    discovered that the subcellular distribution of a tagged version of ALG-2 could be directed by physiological external stimuli (including ATP, EGF, prostaglandin, histamine), which provoke intracellular Ca2+ oscillations. Cellular stimulation led to a redistribution of ALG-2 from the cytosol to a punctate...... localization in an oscillatory fashion unitemporally with Ca2+ oscillations, whereas a Ca2+-binding deficient mutant of ALG-2 did not redistribute. Using tagged ALG-2 as bait we identified its novel target protein Sec31A and based on the partial colocalization of endogenous ALG-2 and Sec31A we propose that ALG...

  17. 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.

  18. Investigation of Transverse Oscillation Method

    DEFF Research Database (Denmark)

    Udesen, Jesper; Jensen, Jørgen Arendt

    2006-01-01

    oscillation and an axial oscillation in the pulse echo field. The theory behind the creation of the double oscillation pulse echo field is explained as well as the theory behind the estimation of the vector velocity. A parameter study of the method is performed, using the ultrasound simulation program Field...... II. A virtual linear array transducer with center frequency 7 MHz and 128 active elements is created, and a virtual blood vessel of radius 6.4 mm is simulated. The performance of the TO method is found around an initial point in the parameter space. The parameters varied are: flow angle, transmit...... focus depth, receive apodization, pulse length, transverse wave length, number of emissions, signal to noise ratio, and type of echo canceling filter used. Using the experimental scanner RASMUS, the performance of the TO method is evaluated. An experimental flowrig is used to create laminar parabolic...

  19. 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.

  20. Sustainable Soesterkwartier

    NARCIS (Netherlands)

    Abrahams, H.; Goosen, H.; Jong, de F.; Sickmann, J.; Prins, D.

    2010-01-01

    The municipality of Amersfoort wants to construct an endurable and sustainable eco-town in the Soesterkwartier neighbourhood, by taking future climate change into account. The impact of climate change at the location of the proposed eco-town was studied by a literature review.

  1. Sustainable agriculture

    International Development Research Centre (IDRC) Digital Library (Canada)

    New farming techniques, better food security. Since 1970, IDRC-supported research has introduced sustainable agricultural practices to farmers and communities across the devel- oping world. The result: higher productivity, less poverty, greater food security, and a healthier environment. Opportunities grow on trees in ...

  2. Sustainable Development

    African Journals Online (AJOL)

    Tsegai Berhane Ghebretekle

    Abstract. This article examines the concept of sustainable development after the Post-. 2015 Paris Climate Change Agreement with particular emphasis on Ethiopia. Various African countries are vulnerable to climate change, as is evidenced by recent droughts. Ethiopia is selected as a case study in light of its pace in.

  3. Sustainable machining

    CERN Document Server

    2017-01-01

    This book provides an overview on current sustainable machining. Its chapters cover the concept in economic, social and environmental dimensions. It provides the reader with proper ways to handle several pollutants produced during the machining process. The book is useful on both undergraduate and postgraduate levels and it is of interest to all those working with manufacturing and machining technology.

  4. Architecture Sustainability

    NARCIS (Netherlands)

    Avgeriou, Paris; Stal, Michael; Hilliard, Rich

    2013-01-01

    Software architecture is the foundation of software system development, encompassing a system's architects' and stakeholders' strategic decisions. A special issue of IEEE Software is intended to raise awareness of architecture sustainability issues and increase interest and work in the area. The

  5. Sustainability reporting

    NARCIS (Netherlands)

    Kolk, A.

    2005-01-01

    This article gives an overview of developments in sustainability (also sometimes labelled corporate social responsibility) reporting. It The article will first briefly indicate how accountability on social and environmental issues started, already in the 1970s when social reports were published.

  6. Exergy sustainability.

    Energy Technology Data Exchange (ETDEWEB)

    Robinett, Rush D. III (.; ); Wilson, David Gerald; Reed, Alfred W.

    2006-05-01

    Exergy is the elixir of life. Exergy is that portion of energy available to do work. Elixir is defined as a substance held capable of prolonging life indefinitely, which implies sustainability of life. In terms of mathematics and engineering, exergy sustainability is defined as the continuous compensation of irreversible entropy production in an open system with an impedance and capacity-matched persistent exergy source. Irreversible and nonequilibrium thermodynamic concepts are combined with self-organizing systems theories as well as nonlinear control and stability analyses to explain this definition. In particular, this paper provides a missing link in the analysis of self-organizing systems: a tie between irreversible thermodynamics and Hamiltonian systems. As a result of this work, the concept of ''on the edge of chaos'' is formulated as a set of necessary and sufficient conditions for stability and performance of sustainable systems. This interplay between exergy rate and irreversible entropy production rate can be described as Yin and Yang control: the dialectic synthesis of opposing power flows. In addition, exergy is shown to be a fundamental driver and necessary input for sustainable systems, since exergy input in the form of power is a single point of failure for self-organizing, adaptable systems.

  7. Sustainable processing

    DEFF Research Database (Denmark)

    Kristensen, Niels Heine

    2004-01-01

    Kristensen_NH and_Beck A: Sustainable processing. In Otto Schmid, Alexander Beck and Ursula Kretzschmar (Editors) (2004): Underlying Principles in Organic and "Low-Input Food" Processing - Literature Survey. Research Institute of Organic Agriculture FiBL, CH-5070 Frick, Switzerland. ISBN 3-906081-58-3...

  8. Sustainable finance

    NARCIS (Netherlands)

    dr. Margreet F. Boersma-de Jong

    2012-01-01

    Presentation for Springschool of Strategy, University of Groningen, 10 October 2012. The role of CSR is to stimulate ethical behaviour, and as a result, mutual trust in society. Advantage of CSR for the company and the evolution of CSR. From CSR to Sustainable Finance: how does CSR influence

  9. Hidden symmetries of deformed oscillators

    Directory of Open Access Journals (Sweden)

    Sergey Krivonos

    2017-11-01

    Full Text Available We associate with each simple Lie algebra a system of second-order differential equations invariant under a non-compact real form of the corresponding Lie group. In the limit of a contraction to a Schrödinger algebra, these equations reduce to a system of ordinary harmonic oscillators. We provide two clarifying examples of such deformed oscillators: one system invariant under SO(2,3 transformations, and another system featuring G2(2 symmetry. The construction of invariant actions requires adding semi-dynamical degrees of freedom; we illustrate the algorithm with the two examples mentioned.

  10. Oscillating-Coolant Heat Exchanger

    Science.gov (United States)

    Scotti, Stephen J.; Blosser, Max L.; Camarda, Charles J.

    1992-01-01

    Devices useful in situations in which heat pipes inadequate. Conceptual oscillating-coolant heat exchanger (OCHEX) transports heat from its hotter portions to cooler portions. Heat transported by oscillation of single-phase fluid, called primary coolant, in coolant passages. No time-averaged flow in tubes, so either heat removed from end reservoirs on every cycle or heat removed indirectly by cooling sides of channels with another coolant. Devices include leading-edge cooling devices in hypersonic aircraft and "frost-free" heat exchangers. Also used in any situation in which heat pipe used and in other situations in which heat pipes not usable.

  11. Ladder operators for isospectral oscillators

    Science.gov (United States)

    Seshadri, S.; Balakrishnan, V.; Lakshmibala, S.

    1998-02-01

    We present, for the isospectral family of oscillator Hamiltonians, a systematic procedure for constructing raising and lowering operators satisfying any prescribed "distorted" Heisenberg algebra (including the q-generalization). This is done by means of an operator transformation implemented by a shift operator. The latter is obtained by solving an appropriate partial isometry condition in the Hilbert space. Formal representations of the nonlocal operators concerned are given in terms of pseudo-differential operators. Using the new annihilation operators, new classes of coherent states are constructed for isospectral oscillator Hamiltonians. The corresponding Fock-Bargmann representations are also considered, with specific reference to the order of the entire function family in each case.

  12. Oscillator strengths for Be I

    Energy Technology Data Exchange (ETDEWEB)

    Ates, Sule, E-mail: suleates@selcuk.edu.tr; Oezarslan, Selma; Celik, Gueltekin; Taser, Mehmet

    2012-07-15

    The electric dipole oscillator strengths for lines between some singlet and triplet levels have been calculated using the weakest bound electron potential model theory and the quantum defect orbital theory for Be I. In the calculations both multiplet and fine structure transitions are studied. We employed both the numerical Coulomb approximation method and numerical non-relativistic Hartree-Fock wavefunctions for expectation values of radii. The necessary energy values have been taken from experimental energy data in the literature. The calculated oscillator strengths have been compared with available theoretical results. A good agreement with the results in the literature has been obtained.

  13. The non-local oscillator

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-08-01

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

  14. 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...

  15. Internal noise-sustained circadian rhythms in a Drosophila model.

    Science.gov (United States)

    Li, Qianshu; Lang, Xiufeng

    2008-03-15

    Circadian rhythmic processes, mainly regulated by gene expression at the molecular level, have inherent stochasticity. Their robustness or resistance to internal noise has been extensively investigated by most of the previous studies. This work focuses on the constructive roles of internal noise in a reduced Drosophila model, which incorporates negative and positive feedback loops, each with a time delay. It is shown that internal noise sustains reliable oscillations with periods close to 24 h in a region of parameter space, where the deterministic kinetics would evolve to a stable steady state. The amplitudes of noise-sustained oscillations are significantly affected by the variation of internal noise level, and the best performance of the oscillations could be found at an optimal noise intensity, indicating the occurrence of intrinsic coherence resonance. In the oscillatory region of the deterministic model, the coherence of noisy circadian oscillations is suppressed by internal noise, while the period remains nearly constant over a large range of noise intensity, demonstrating robustness of the Drosophila model for circadian rhythms to intrinsic noise. In addition, the effects of time delay in the positive feedback on the oscillations are also investigated. It is found that the time delay could efficiently tune the performance of the noise-sustained oscillations. These results might aid understanding of the exploitation of intracellular noise in biochemical and genetic regulatory systems.

  16. Equatorial oscillations maintained by gravity waves as described with the Doppler Spread Parameterization: I. Numerical experiments

    Science.gov (United States)

    Mayr, H. G.; Mengel, J. G.; Chan, K. L.

    1998-01-01

    increase significantly above six months. (5) Under oscillation conditions, the height variations in the GW vertical wave numbers reveal a staircase pattern reflecting the intermittence characteristic of the wave interaction. It reveals the nonlinearity of the GW interaction to be of third (odd) order, which has the distinctive property that it can feed and maintain the fundamental harmonic of the oscillation-considered a prerequisite for sustaining the oscillations without external time dependent source. In the companion paper, an analytical model of the equatorial oscillation is presented which describes some of the trends reported here.

  17. Multimode phase-locking in a Josephson parametric oscillator

    Science.gov (United States)

    Bengtsson, Andreas; Wustmann, Waltraut; Shumeiko, Vitaly; Delsing, Per; Bylander, Jonas

    Frequency-tunable resonators are versatile tools for microwave amplification at the quantum limit of sensitivity, interaction between qubits and radiation in the circuit-QED architecture, and strong-coupling microwave quantum optics. We investigated non-degenerate parametric resonance in multimode microwave superconducting resonators. Pumping is realized by modulating magnetic flux through the SQUID attached to the cavity. Pumping at the sum-frequency of two modes provides parametric amplification. For low pumping strength, we observe the generation of two-mode squeezed states, i.e., entangled modes when the input is the vacuum. For high pumping strength, exceeding a parametric instability threshold, self-sustained parametric oscillations are observed in each mode. The sum of the phases of the mode fields is fixed, while the difference is uncertain in the classical limit, and undergoes diffusion under the effect of quantum noise. This phenomenon significantly changes the statistics of entangled modes in the oscillator state.

  18. SUSTAINABLE CORPORATE AND SUSTAINABLE DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    DORU CÎRNU

    2017-06-01

    Full Text Available In recent decades, the image of the international business environment has changed significantly. Studies conducted by UNCTAD shows that corporate phenomenon developments in the world economy is growing. Without claiming to present an exhaustive topic so vast we tried to capture some "facets" of sustainable development from the perspective of multinational corporations, given the expansion of these economic entities and strengthening their power in the global economy. We present more negative aspects of the actions of multinational corporations in terms of sustainable development, it is very important to know both sides of the coin, which will not only help transnational giants including release. Based on issues such as corporate social responsibility, environmental pollution and workers' rights, we sought to counter official statements. The conclusion is that these economic entities are real forces that can not be ignored in today's world and the obvious problem of sustainable development can not be addressed independently of the phenomenon, context we also identified some possible solutions to conflict of corporations and essence of the concept of sustainable development.

  19. B0s Oscillation Results

    CERN Document Server

    Willocq, S

    2002-01-01

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

  20. Oscillating solitons in nonlinear optics

    Indian Academy of Sciences (India)

    Abstract. Oscillating solitons are obtained in nonlinear optics. Analytical study of the variable- coefficient nonlinear Schrödinger equation, which is used to describe the soliton propagation in those systems, is carried out using the Hirota's bilinear method. The bilinear forms and analytic soliton solutions are derived, and the ...

  1. Chemical Oscillations-Mathematical Modelling

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 7. Chemical Oscillations - Mathematical Modelling ... Protein Science and Engineering Unit Institute of Microbial Technology Sector 39A Chandigarh 160 036; Department of Chemistry and Centre for Advanced Studies in Chemistry Punjab ...

  2. Cubication of Conservative Nonlinear Oscillators

    Science.gov (United States)

    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…

  3. Linearization of Conservative Nonlinear Oscillators

    Science.gov (United States)

    Belendez, A.; Alvarez, M. L.; Fernandez, E.; Pascual, I.

    2009-01-01

    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…

  4. Sum rules for neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Kobzarev, I.Yu.; Nartem' yanov, B.V.; Okun, L.B.; Shchepkin, M.G. (Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow. Inst. Teoreticheskoj i Ehksperimental' noj Fiziki)

    1982-05-01

    Sum rules for neutrino oscillations have been obtained. The effects due to the neutrino masses are taken into account, msub(..nu..) being not assumed to be a small parameter. Study of the ''binary'' lsub(i)sup(-) ..-->.. ..nu.. ..-->.. lsub(k)sup(+-) process permits to accurately take into account neutrino masses and to obtain expressions for the cross sections oscillating as functions of distance L between the points of neutrino production and absorption. In the case of Dirac or left Majoran masses obtained is the sum rule according to which the cross section sigma(lsub(i)sup(-) ..-->.. lsub(k)sup(-)) summarized with the weight 1/vsub(k) by aromas of final lepton remains constant (exactly, decrease as 1/L/sup 2/) and it does not oscillate. In the case of left Majoran masses there is admixture of antineutrino due to which the lsub(i)sup(-) ..-->.. lsub(k)sup(+) process is possible. In this case both components (neutrino with antineutrino admixture) oscillates independently and there exists analogous sum rule for the sigma(lsub(i)sup(-) ..-->.. lsub(k)sup(+)) cross section.

  5. Discovery of atmospheric neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Tokyo Univ., Inst. for Cosmic Ray Research, Kashiwa, Chiba (Japan)

    2003-05-01

    Cosmic ray particles entering the atmosphere interact with the air nuclei produce neutrinos. These neutrinos are called atmospheric neutrinos. The atmospheric neutrino anomaly observed in Kamiokande is now understood as due to neutrino oscillations by high statistics measurements of the atmospheric neutrinos in Super-Kamiokande. The studies of the atmospheric neutrinos have matured into detailed studies of neutrino masses and mixings. (author)

  6. 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.

  7. Sustainable Consumption

    DEFF Research Database (Denmark)

    Røpke, Inge

    2015-01-01

    in wider social, economic and technological frameworks is emphasised. In particular, the chapter is inspired by practice theory and transition theory. First, various trends in consumption are outlined to highlight some of the challenges for sustainability transitions. Then, it is discussed how consumption...... patterns are shaped over time and what should be considered in sustainability strategies. While discussions on consumption often take their point of departure in the perspective of the individual and then zoom to the wider context, the present approach is the opposite. The outline starts with the basic...... biophysical, distributional and economic conditions for high consumption in rich countries and then zooms in on the coevolution of provision systems and consumption, and how consumption is shaped by practices and projects in everyday life. Furthermore, the paper discusses whether and how transition...

  8. Sustainable Buildings

    DEFF Research Database (Denmark)

    Tommerup, Henrik M.; Elle, Morten

    The scientific community agrees that: all countries must drastically and rapidly reduce their CO2 emissions and that energy efficient houses play a decisive role in this. The general attitude at the workshop on Sustainable Buildings was that we face large and serious climate change problems that ...... that need urgent action. The built environment is an obvious area to put effort into because of the large and cost-effective energy saving potential and potential for Renewable Energy-based supply systems for buildings.......The scientific community agrees that: all countries must drastically and rapidly reduce their CO2 emissions and that energy efficient houses play a decisive role in this. The general attitude at the workshop on Sustainable Buildings was that we face large and serious climate change problems...

  9. Analytic Neutrino Oscillation Probabilities in Matter: Revisited

    Energy Technology Data Exchange (ETDEWEB)

    Parke, Stephen J. [Fermilab; Denton, Peter B. [Copenhagen U.; Minakata, Hisakazu [Madrid, IFT

    2018-01-02

    We summarize our recent paper on neutrino oscillation probabilities in matter, explaining the importance, relevance and need for simple, highly accurate approximations to the neutrino oscillation probabilities in matter.

  10. Altered temporal correlations in parietal alpha and prefrontal theta oscillations in early-stage Alzheimer disease

    NARCIS (Netherlands)

    Montez, T.; Poil, S.S.; Jones, B.F.; Manshanden, I.; Verbunt, J.P.A.; van Dijk, B.W.; Brussaard, A.B.; van Ooyen, A.; Stam, C.J.; Scheltens, P.; Linkenkaer-Hansen, K.

    2009-01-01

    Encoding and retention of information in memory are associated with a sustained increase in the amplitude of neuronal oscillations for up to several seconds. We reasoned that coordination of oscillatory activity over time might be important for memory and, therefore, that the amplitude modulation of

  11. Acoustically levitated dancing drops: Self-excited oscillation to chaotic shedding

    Science.gov (United States)

    Lin, Po-Cheng; I, Lin

    2016-02-01

    We experimentally demonstrate self-excited oscillation and shedding of millimeter-sized water drops, acoustically levitated in a single-node standing waves cavity, by decreasing the steady acoustic wave intensity below a threshold. The perturbation of the acoustic field by drop motion is a possible source for providing an effective negative damping for sustaining the growing amplitude of the self-excited motion. Its further interplay with surface tension, drop inertia, gravity and acoustic intensities, select various self-excited modes for different size of drops and acoustic intensity. The large drop exhibits quasiperiodic motion from a vertical mode and a zonal mode with growing coupling, as oscillation amplitudes grow, until falling on the floor. For small drops, chaotic oscillations constituted by several broadened sectorial modes and corresponding zonal modes are self-excited. The growing oscillation amplitude leads to droplet shedding from the edges of highly stretched lobes, where surface tension no longer holds the rapid expanding flow.

  12. Quantum oscillations in the chiral magnetic conductivity

    Science.gov (United States)

    Kaushik, Sahal; Kharzeev, Dmitri E.

    2017-06-01

    In strong magnetic field, the longitudinal magnetoconductivity in three-dimensional chiral materials is shown to exhibit a new type of quantum oscillations arising from the chiral magnetic effect (CME). These quantum CME oscillations are predicted to dominate over the Shubnikov-de Haas (SdH) ones in chiral materials with an approximately conserved chirality of quasiparticles at strong magnetic fields. The phase of quantum CME oscillations differs from the phase of the conventional SdH oscillations by π /2 .

  13. Nonlinear analysis of ring oscillator circuits

    KAUST Repository

    Ge, Xiaoqing

    2010-06-01

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

  14. Assessing the quality of stochastic oscillations

    Indian Academy of Sciences (India)

    Population dynamics; stochastic oscillations. ... We propose a quantification of the oscillatory appearance of the fluctuating populations, and show that good stochastic oscillations are present if a parameter of the macroscopic model is small, and that no microscopic model will show oscillations if that parameter is large.

  15. 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 numerical...

  16. 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...

  17. Scleronomic Holonomic Constraints and Conservative Nonlinear Oscillators

    Science.gov (United States)

    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…

  18. Coherent states for the Legendre oscillator

    OpenAIRE

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

    2003-01-01

    A new oscillator-like system called by the Legendre oscillator is introduced in this note. The two families of coherent states (coherent states as eigenvectors of the annihilation operator and the Klauder-Gazeau temporally stable coherent states) are defined and investigated for this oscillator.

  19. SUSTAINABLE CHEMISTRY FOR SUSTAINABLE INDUSTRY

    Directory of Open Access Journals (Sweden)

    G. Rizzuto

    2015-01-01

    Full Text Available Foundry Alfe Chem is an industrial reality working in the field of lubrication and chemical auxiliaries for industrial processes, which falls within the framework of the emerging and increasingly important «green chemistry». The goal of the company is to develop products that are more environmentally friendly by using raw materials from renewable sources; specifically, Foundry Alfe Chem has a program of self-sustainability that contemplates, for the foreseeable future, the direct production of renewable raw materials. The company has developed a new dedicated product line, Olitema, whose purpose is to offer highly technological solutions with complete environmental sustainability. In this context, Foundry Alfe CHEM has created a new product which represents a breakthrough in the class of HFC hydraulic fluids: Ecosafe Plus is a biodegradable fire-resistant hydraulic fluid with high engineering and technological performances, high environmental sustainability and the best security guarantees in workplaces. Its formulation is glycols-free, and it allows for easier disposal of the exhausted fluid, compared to a traditional water/ glycol-based HFC hydraulic fluid. For what concern the technological properties, Ecosafe Plus has been tested by accredited laboratories with tribological trials (4 Ball wear test ASTM D 4172, Ball on disc test ASTM 6425, Brugger test DIN 51347, Vickers test ASTM D 2882, with elastomer compatibility test (ASTM D 471 and biodegradability test (OECD 310 F.

  20. Slow oscillations orchestrating fast oscillations and memory consolidation.

    Science.gov (United States)

    Mölle, Matthias; Born, Jan

    2011-01-01

    Slow-wave sleep (SWS) facilitates the consolidation of hippocampus-dependent declarative memory. Based on the standard two-stage memory model, we propose that memory consolidation during SWS represents a process of system consolidation which is orchestrated by the neocortical memory. The slow oscillations temporally group neuronal activity into up-states of strongly enhanced neuronal activity and down-states of neuronal silence. In a feed-forward efferent action, this grouping is induced not only in the neocortex but also in other structures relevant to consolidation, namely the thalamus generating 10-15Hz spindles, and the hippocampus generating sharp wave-ripples, with the latter well known to accompany a replay of newly encoded memories taking place in hippocampal circuitries. The feed-forward synchronizing effect of the slow oscillation enables the formation of spindle-ripple events where ripples and accompanying reactivated hippocampal memory information become nested into the single troughs of spindles. Spindle-ripple events thus enable reactivated memory-related hippocampal information to be fed back to neocortical networks in the excitable slow oscillation up-state where they can induce enduring plastic synaptic changes underlying the effective formation of long-term memories. Copyright © 2011 Elsevier B.V. All rights reserved.

  1. Measuring neutrino oscillation parameters using $\

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-01-01

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

  2. Sustainable Procurement

    DEFF Research Database (Denmark)

    Telles, Pedro; Ølykke, Grith Skovgaard

    2017-01-01

    and within it how sustainable requirements have increased the level of compliance required, particularly regulatory compliance. Compliance was already present in previous EU public procurement frameworks, but its extent on Directive 2014/24/EU leads the authors to consider the current legal framework...... as subject to substantial regulatory compliance obligations external to the process of procurement. In short, procurement has been transformed in a way to enforce regulatory obligations that are not intrinsic to the process of buying. This leads to the conclusion that questions such as the cost and trade...

  3. Sustainable consumption and marketing

    NARCIS (Netherlands)

    Dam, van Y.K.

    2016-01-01

    Sustainable development in global food markets is hindered by the discrepancy between positive consumer attitudes towards sustainable development or sustainability and the lack of corresponding sustainable consumption by a majority of consumers. Apparently for many (light user) consumers the

  4. Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator

    OpenAIRE

    Bibha Kumari; Nisha Gupta

    2014-01-01

    This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA) on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the ant...

  5. Experimental studies of neutrino oscillations

    CERN Document Server

    Kajita, Takaaki

    2016-01-01

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

  6. 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.

  7. Quantum transduction with mechanical oscillators

    Science.gov (United States)

    Lehnert, Konrad

    In modern information technology, micromechanical oscillators are ubiquitous signal processing elements. Because the speed of sound is so slow compared to the speed of light, mechanical structures create superb compact filters and clocks. Moreover they convert force and acceleration signals into more easily processed electrical signals. Although these humble devices appear manifestly classical, they can exhibit quantum behavior when their vibrations are strongly coupled to optical light or to microwave electricity. I will describe our progress in using this recent result to develop quantum information processing elements. First, we are developing a device that uses a mechanical oscillator to transfer information noiselessly between electrical and optical domains. Second, we prepare propagating microwave fields in superpositions of 0 and 1 photon, and use an electromechanical device to store and amplify these fragile quantum bits. Work supported by AFOSR MURI:FA9550-15-1-0015, NSF under Grant Number 1125844, and the Gordon and Betty Moore Foundation.

  8. Memristor-based reactance-less oscillator

    KAUST Repository

    Zidan, Mohammed A.

    2012-10-02

    The first reactance-less oscillator is introduced. By using a memristor, the oscillator can be fully implemented on-chip without the need for any capacitors or inductors, which results in an area-efficient fully integrated solution. The concept of operation of the proposed oscillator is explained and detailed mathematical analysis is introduced. Closed-form expressions for the oscillation frequency and oscillation conditions are derived. Finally, the derived equations are verified with circuit simulations showing excellent agreement. © 2011 The Institution of Engineering and Technology.

  9. Cyanohydrin reactions enhance glycolytic oscillations in yeast

    DEFF Research Database (Denmark)

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

    2015-01-01

    Synchronous metabolic oscillations can be induced in yeast by addition of glucose and removal of extracellular acetaldehyde (ACAx). Compared to other means of ACAx removal, cyanide robustly induces oscillations, indicating additional cyanide reactions besides ACA to lactonitrile conversion. Here...... for ~66% of total cyanide removal. Simulations of our updated computational model show that intracellular cyanide reactions increase the amplitude of oscillations and that cyanide addition lowers [ACA] instantaneously. We conclude that cyanide provides the following means of inducing global oscillations......: a) by reducing [ACAx] relative to oscillation amplitude, b) by targeting multiple intracellular carbonyl compounds during fermentation, and c) by acting as a phase resetting stimulus....

  10. 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.

  11. Oscillations and Waves in Sunspots

    Directory of Open Access Journals (Sweden)

    Elena Khomenko

    2015-11-01

    Full Text Available A magnetic field modifies the properties of waves in a complex way. Significant advances have been made recently in our understanding of the physics of sunspot waves with the help of high-resolution observations, analytical theories, as well as numerical simulations. We review the current ideas in the field, providing the most coherent picture of sunspot oscillations as by present understanding.

  12. Renormalization for free harmonic oscillators

    OpenAIRE

    Sonoda, H.

    2013-01-01

    We introduce a model of free harmonic oscillators that requires renormalization. The model is similar to but simpler than the soluble Lee model. We introduce two concrete examples: the first, resembling the three dimensional $\\phi^4$ theory, needs only mass renormalization, and the second, resembling the four dimensional $\\phi^4$ theory and the Lee model, needs additional renormalization of a coupling and a wave function.

  13. Oscillations of a polarizable vacuum

    Directory of Open Access Journals (Sweden)

    James G. Gilson

    1991-01-01

    Full Text Available A classical basis for one-dimensional Schrödinger quantum theory is constructed from simple vacuum polarization harmonic oscillators within standard stochastic theory. The model is constructed on a two-dimensional phase configuration surface with phase velocity vectors that have a speed of light zitterbewegung behaviour character. The system supplies a natural Hermitian scalar product describing probability density which is derived from angular momentum considerations. The generality of the model which is extensive is discussed.

  14. Automatic oscillator frequency control system

    Science.gov (United States)

    Smith, S. F. (Inventor)

    1985-01-01

    A frequency control system makes an initial correction of the frequency of its own timing circuit after comparison against a frequency of known accuracy and then sequentially checks and corrects the frequencies of several voltage controlled local oscillator circuits. The timing circuit initiates the machine cycles of a central processing unit which applies a frequency index to an input register in a modulo-sum frequency divider stage and enables a multiplexer to clock an accumulator register in the divider stage with a cyclical signal derived from the oscillator circuit being checked. Upon expiration of the interval, the processing unit compares the remainder held as the contents of the accumulator against a stored zero error constant and applies an appropriate correction word to a correction stage to shift the frequency of the oscillator being checked. A signal from the accumulator register may be used to drive a phase plane ROM and, with periodic shifts in the applied frequency index, to provide frequency shift keying of the resultant output signal. Interposition of a phase adder between the accumulator register and phase plane ROM permits phase shift keying of the output signal by periodic variation in the value of a phase index applied to one input of the phase adder.

  15. Neutrino Oscillation Experiment at JHF

    CERN Multimedia

    2002-01-01

    T2K is a long baseline neutrino experiment designed to investigate how neutrinos change from one flavor to another as they travel (neutrino oscillations). An intense beam of muon neutrinos is generated at the J-PARC nuclear physics site on the East coast of Japan and directed across the country to the Super-Kamiokande neutrino detector in the mountains of western Japan. The beam is measured once before it leaves the J-PARC site, using the near detector ND280, and again at Super-K, 295 km away: the change in the measured intensity and composition of the beam is used to provide information on the properties of neutrinos. The high intensity neutrino beam is produced in an off-axis configuration. The peak neutrino energy is tuned to the oscillation maximum of ∼ 0.6 GeV to maximize the sensitivity to neutrino oscillations. The science goals of T2K can be summarized as follows: •\tsearch for CP violation in the neutrino sector •\tdiscovery of νμ → νe ( i.e. the confirmation that θ13 > 0 ) •\tprecision ...

  16. Capacitive coupling synchronizes autonomous microfluidic oscillators.

    Science.gov (United States)

    Lesher-Perez, Sasha Cai; Zhang, Chao; Takayama, Shuichi

    2018-01-31

    Even identically-designed autonomous microfluidic oscillators have device-to-device oscillation variability that arises due to inconsistencies in fabrication, materials, and operation conditions. This work demonstrates, experimentally and theoretically, that with appropriate capacitive coupling these microfluidic oscillators can be synchronized. The size and characteristics of the capacitive coupling needed and the range of input flow rate differences that can be synchronized are also characterized. In addition to device-to-device variability, there is also within-device oscillation noise that arises. An additional advantage of coupling multiple fluidic oscillators together is that the oscillation noise decreases. The ability to synchronize multiple autonomous oscillators is also a first step towards enhancing their usefulness as tools for biochemical research applications where multiplicate experiments with identical temporal-stimulation conditions are required. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  17. Microwave balanced oscillators and frequency doublers

    CERN Document Server

    Siripon, N

    2002-01-01

    The research presented in this thesis is on the application of the injection-locked oscillator technique to microwave balanced oscillators. The balanced oscillator design is primarily analysed using the extended resonance technique. A transmission line is connected between the two active devices, so that the active device resonate each other. The electrical length of the transmission line is also analysed for the balanced oscillation condition. The balanced oscillator can be viewed with the negative resistance model and the feedback model. The former model is characterised at a circuit plane where the feedback network is cut. By using both the negative-resistance oscillator model and the feedback model, the locking range of the oscillator is analysed by extending Kurokawa's theory. This analysis demonstrates the locking range of the injection phenomenon, where the injection frequency is either close to the free-running frequency, close to (1/n) x free-running frequency or close to n x the free-running frequen...

  18. Virtual Sustainability

    Directory of Open Access Journals (Sweden)

    William Sims Bainbridge

    2010-09-01

    Full Text Available In four ways, massively multiplayer online role-playing games may serve as tools for advancing sustainability goals, and as laboratories for developing alternatives to current social arrangements that have implications for the natural environment. First, by moving conspicuous consumption and other usually costly status competitions into virtual environments, these virtual worlds might reduce the need for physical resources. Second, they provide training that could prepare individuals to be teleworkers, and develop or demonstrate methods for using information technology to replace much transportation technology, notably in commuting. Third, virtual worlds and online games build international cooperation, even blending national cultures, thereby inching us toward not only the world consciousness needed for international agreements about the environment, but also toward non-spatial government that cuts across archaic nationalisms. Finally, realizing the potential social benefits of this new technology may urge us to reconsider a number of traditional societal institutions.

  19. Sustainability; Sustentabilidade

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2009-10-15

    This chapter analyses the production chain of ethanol, considering the impacts on the quality of the air, water supplies, soil occupation and biodiversity, and the efforts for the soil preservation. It is pointed out the activities of the production cycle and use of bio ethanol due to great uncertainties as far the environmental impacts is concerning and that will deserve more attention in future evaluations. At same time, the chapter highlights another activities where the present acknowledge is sufficient to assure the control and/or prediction of consequences of the desired intervention on the environment media to accommodate the sugar and ethanol production expansion. The consideration is not conservative but to promote the sustainable development.

  20. Mechano-chemical oscillations and waves in reactive gels

    Science.gov (United States)

    Yashin, Victor V.; Kuksenok, Olga; Dayal, Pratyush; Balazs, Anna C.

    2012-06-01

    We review advances in a new area of interdisciplinary research that concerns phenomena arising from inherent coupling between non-linear chemical dynamics and mechanics. This coupling provides a route for chemical-to-mechanical energy transduction, which enables materials to exhibit self-sustained oscillations and/or waves in both concentration and deformation fields. We focus on synthetic polymer gels, where the chemo-mechanical behavior can be engineered into the material. We provide a brief review of experimental observations on several types of chemo-mechanical oscillations in gels. Then, we discuss methods used to theoretically and computationally model self-oscillating polymer gels. The rest of the paper is devoted to describing results of theoretical and computational modeling of gels that undergo the oscillatory Belousov-Zhabotinsky (BZ) reaction. We discuss a remarkable form of mechano-chemical transduction in these materials, where the application of an applied force or mechanical contact can drive the system to switch between different dynamical behavior, or alter the mechanical properties of the material. Finally, we discuss ways in which photosensitive BZ gels could be used to fabricate biomimetic self-propelled objects. In particular, we describe how non-uniform illumination can be used to direct the movement of BZ gel ‘worms’ along complex paths, guiding them to bend, reorient and turn.

  1. Sustainability Science Needs Sustainable Data!

    Science.gov (United States)

    Downs, R. R.; Chen, R. S.

    2013-12-01

    Sustainability science (SS) is an 'emerging field of research dealing with the interactions between natural and social systems, and with how those interactions affect the challenge of sustainability: meeting the needs of present and future generations while substantially reducing poverty and conserving the planet's life support systems' (Kates, 2011; Clark, 2007). Bettencourt & Kaur (2011) identified more than 20,000 scientific papers published on SS topics since the 1980s with more than 35,000 distinct authors. They estimated that the field is currently growing exponentially, with the number of authors doubling approximately every 8 years. These scholars are undoubtedly using and generating a vast quantity and variety of data and information for both SS research and applications. Unfortunately we know little about what data the SS community is actually using, and whether or not the data that SS scholars generate are being preserved for future use. Moreover, since much SS research is conducted by cross-disciplinary, multi-institutional teams, often scattered around the world, there could well be increased risks of data loss, reduced data quality, inadequate documentation, and poor long-term access and usability. Capabilities and processes therefore need to be established today to support continual, reliable, and efficient preservation of and access to SS data in the future, especially so that they can be reused in conjunction with future data and for new studies not conceived in the original data collection activities. Today's long-term data stewardship challenges include establishing sustainable data governance to facilitate continuing management, selecting data to ensure that limited resources are focused on high priority SS data holdings, securing sufficient rights to allow unforeseen uses, and preparing data to enable use by future communities whose specific research and information needs are not yet known. Adopting sustainable models for archival

  2. Separation control with fluidic oscillators in water

    Science.gov (United States)

    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.

  3. Equatorial oscillations maintained by gravity waves as described with the Doppler Spread Parameterization: II. Heuristic analysis

    Science.gov (United States)

    Mayr, H. G.; Hartle, R. E.; Chan, K. L.

    1998-01-01

    The Doppler Spread Parameterization (DSP) for gravity waves (GW) developed by Hines is applied to the zonal momentum budget at the equator. For sufficiently large oscillation amplitudes in the background zonal winds, comparable to the GW induced wind variability, the momentum source is intermittent and as such it represents a nonlinearity of third or generally odd order. This kind of nonlinearity generates, besides higher harmonics, the fundamental harmonic itself which is retained in a simplified analytical solution that can describe self-sustained oscillations without invoking external, time dependent forcing. The formulation is discussed to provide some understanding of the numerical results presented in the companion paper.

  4. Waves and Oscillations in Plasmas

    CERN Document Server

    Pecseli, Hans L

    2012-01-01

    The result of more than 15 years of lectures in plasma sciences presented at universities in Denmark, Norway, and the United States, Waves and Oscillations in Plasmas addresses central issues in modern plasma sciences. The book covers fluid models as well as kinetic plasma models, including a detailed discussion of, for instance, collisionless Landau damping. Offering a clear separation of linear and nonlinear models, the book can be tailored for readers of varying levels of expertise.Designed to provide basic training in linear as well as nonlinear plasma dynamics, and practical in areas as d

  5. 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.

  6. Wave Physics Oscillations - Solitons - Chaos

    CERN Document Server

    Nettel, Stephen

    2009-01-01

    This textbook is intended for those second year undergraduates in science and engineering who will later need an understanding of electromagnetic theory and quantum mechanics. The classical physics of oscillations and waves is developed at a more advanced level than has been customary for the second year, providing a basis for the quantum mechanics that follows. In this new edition the Green's function is explained, reinforcing the integration of quantum mechanics with classical physics. The text may also form the basis of an "introduction to theoretical physics" for physics majors. The concluding chapters give special attention to topics in current wave physics: nonlinear waves, solitons, and chaotic behavior.

  7. 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.

  8. Neutrino Oscillation Studies with Reactors

    CERN Document Server

    Vogel, Petr; Zhang, Chao

    2015-01-01

    Nuclear reactors are one of the most intense, pure, controllable, cost-effective, and well-understood sources of neutrinos. Reactors have played a major role in the study of neutrino oscillations, a phenomenon that indicates that neutrinos have mass and that neutrino flavors are quantum mechanical mixtures. Over the past several decades reactors were used in the discovery of neutrinos, were crucial in solving the solar neutrino puzzle, and allowed the determination of the smallest mixing angle $\\theta_{13}$. In the near future, reactors will help to determine the neutrino mass hierarchy and to solve the puzzling issue of sterile neutrinos.

  9. Design Principles of Biological Oscillators through Optimization: Forward and Reverse Analysis.

    Science.gov (United States)

    Otero-Muras, Irene; Banga, Julio R

    2016-01-01

    From cyanobacteria to human, sustained oscillations coordinate important biological functions. Although much has been learned concerning the sophisticated molecular mechanisms underlying biological oscillators, design principles linking structure and functional behavior are not yet fully understood. Here we explore design principles of biological oscillators from a multiobjective optimization perspective, taking into account the trade-offs between conflicting performance goals or demands. We develop a comprehensive tool for automated design of oscillators, based on multicriteria global optimization that allows two modes: (i) the automatic design (forward problem) and (ii) the inference of design principles (reverse analysis problem). From the perspective of synthetic biology, the forward mode allows the solution of design problems that mimic some of the desirable properties appearing in natural oscillators. The reverse analysis mode facilitates a systematic exploration of the design space based on Pareto optimality concepts. The method is illustrated with two case studies: the automatic design of synthetic oscillators from a library of biological parts, and the exploration of design principles in 3-gene oscillatory systems.

  10. Design Principles of Biological Oscillators through Optimization: Forward and Reverse Analysis

    Science.gov (United States)

    Otero-Muras, Irene; Banga, Julio R.

    2016-01-01

    From cyanobacteria to human, sustained oscillations coordinate important biological functions. Although much has been learned concerning the sophisticated molecular mechanisms underlying biological oscillators, design principles linking structure and functional behavior are not yet fully understood. Here we explore design principles of biological oscillators from a multiobjective optimization perspective, taking into account the trade-offs between conflicting performance goals or demands. We develop a comprehensive tool for automated design of oscillators, based on multicriteria global optimization that allows two modes: (i) the automatic design (forward problem) and (ii) the inference of design principles (reverse analysis problem). From the perspective of synthetic biology, the forward mode allows the solution of design problems that mimic some of the desirable properties appearing in natural oscillators. The reverse analysis mode facilitates a systematic exploration of the design space based on Pareto optimality concepts. The method is illustrated with two case studies: the automatic design of synthetic oscillators from a library of biological parts, and the exploration of design principles in 3-gene oscillatory systems. PMID:27977695

  11. Regulation of circadian gene expression in liver by systemic signals and hepatocyte oscillators.

    Science.gov (United States)

    Kornmann, B; Schaad, O; Reinke, H; Saini, C; Schibler, U

    2007-01-01

    The mammalian circadian timing system has a hierarchical structure, in that a master pacemaker located in the suprachiasmatic nuclei (SCN) coordinates slave oscillators present in virtually all body cells. In both the SCN and peripheral organs, the rhythm-generating oscillators are self-sustained and cell-autonomous, and it is likely that the molecular makeup of master and slave oscillators is nearly identical. However, due to variations in period length, the phase coherence between peripheral oscillators in intact animals must be established by daily signals emanating directly or indirectly from the SCN master clock. The synchronization of individual cellular clocks in peripheral organs is probably accomplished by immediate-early genes that interpret the cyclic systemic signals and convey this phase information to core clock components. This model predicts that circadian gene expression in peripheral organs can be influenced either by systemic signals emanating from the SCN master clock, local oscillators, or both. We developed a transgenic mouse strain in which hepatocyte clocks are only operative when the tetracycline analog doxycycline is added to the food or drinking water. The genome-wide mapping of genes whose cyclic expression in liver does not depend on functional hepatocyte oscillators unveiled putative signaling pathways that may participate in the phase entrainment of peripheral clocks.

  12. Sustainable Scientists

    Energy Technology Data Exchange (ETDEWEB)

    Mills, Evan

    2008-12-31

    Scientists are front and center in quantifying and solving environmental problems. Yet, as a spate of recent news articles in scientific journals point out, much can be done to enhance sustainability within the scientific enterprise itself, particularly by trimming the energy use associated with research facilities and the equipment therein (i,ii,iii, iv). Sponsors of research unwittingly spend on the order of $10 billion each year on energy in the U.S. alone, and the underlying inefficiencies drain funds from the research enterprise while causing 80 MT CO2-equivalent greenhouse-gas emissions (see Box). These are significant sums considering the opportunity costs in terms of the amount of additional research that could be funded and emissions that could be reduced if the underlying energy was used more efficiently. By following commercially proven best practices in facility design and operation, scientists--and the sponsors of science--can cost-effectively halve these costs, while doing their part to put society on alow-carbon diet.

  13. Phase noise and frequency stability in oscillators

    CERN Document Server

    Rubiola, Enrico

    2009-01-01

    Presenting a comprehensive account of oscillator phase noise and frequency stability, this practical text is both mathematically rigorous and accessible. An in-depth treatment of the noise mechanism is given, describing the oscillator as a physical system, and showing that simple general laws govern the stability of a large variety of oscillators differing in technology and frequency range. Inevitably, special attention is given to amplifiers, resonators, delay lines, feedback, and flicker (1/f) noise. The reverse engineering of oscillators based on phase-noise spectra is also covered, and end-of-chapter exercises are given. Uniquely, numerous practical examples are presented, including case studies taken from laboratory prototypes and commercial oscillators, which allow the oscillator internal design to be understood by analyzing its phase-noise spectrum. Based on tutorials given by the author at the Jet Propulsion Laboratory, international IEEE meetings, and in industry, this is a useful reference for acade...

  14. Modes of nanosatellite aerodynamic oscillations in atmosphere

    Science.gov (United States)

    Gerasimov, Yu V.; Ivanov, E. A.; Karetnikov, G. K.; Konstantinova, I. A.; Selivanov, A. B.

    2017-11-01

    The paper is devoted to the results of investigating the dependencies of nanosatellite aerodynamic oscillations frequency on attack angle at different altitudes up to 70 km are defined. The oscillations bandwidths are determined with respect to the geometric parameters for a nanosatellite with 10 kg mass and 6000 kg/m3 average density. The model allows estimating the bandwidth aerodynamic oscillations in the suborbital nanosatellite trajectory based on the given geometry and mass-dimensional parameters.

  15. Characterizing correlations of flow oscillations at bottlenecks

    OpenAIRE

    Kretz, Tobias; Woelki, Marko; Schreckenberg, Michael

    2006-01-01

    "Oscillations" occur in quite different kinds of many-particle-systems when two groups of particles with different directions of motion meet or intersect at a certain spot. We present a model of pedestrian motion that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to hold observables that can be used to characterize different kinds of oscillations.

  16. Characterizing correlations of flow oscillations at bottlenecks

    Science.gov (United States)

    Kretz, Tobias; Wölki, Marko; Schreckenberg, Michael

    2006-02-01

    'Oscillations' occur in quite different kinds of many-particle systems when two groups of particles with different directions of motion meet or intersect at a certain spot. In this work a model of pedestrian motion is presented that is able to reproduce oscillations with different characteristics. The Wald-Wolfowitz test and Gillis' correlated random walk are shown to include observables that can be used to characterize different kinds of oscillations.

  17. Oscillations of neutral B mesons systems

    CERN Document Server

    Boucrot, J

    1999-01-01

    The oscillation phenomenon in the neutral B mesons systems is now well established. The motivations and principles of the measurements are given; then the most recent results from the LEP experiments, the CDF collaboration at Fermilab and the SLD collaboration at SLAC are reviewed. The present world average of the $\\bd$ meson oscillation frequency is $\\dmd = 0.471 \\pm 0.016 \\ps$ and the lower limit on the $\\bs$ oscillation frequency is

  18. Phase-locked Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.

    1991-01-01

    Detailed experimental characterization of the phase-locking at both DC and at microwave frequencies is presented for two closely spaced Josephson soliton (fluxon) oscillators. In the phase-locked state, the radiated microwave power exhibited an effective gain. With one common bias source......, a frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. The interacting soliton oscillators were modeled by two inductively coupled nonlinear transmission lines...

  19. On Rabi oscillations between Bloch bands

    OpenAIRE

    Plötz, Patrick

    2010-01-01

    We study Rabi oscillations between the bands of an arbitrary biased superlattice in a tight-binding model. We reduce the problem to an equation of Whittaker--Hill type and, in absence of any known solutions in closed form, discuss different approximations to describe the oscillations between the Bloch bands. We identify regimes of weak and strong inter-band coupling and compare predictions for these Rabi oscillations to numerical results.

  20. SPIRAL, FUNCTIONS AND OSCILLATING SYSTEMS BESSEL

    OpenAIRE

    Gil Benitez, W.; Universidad Nacional Mayor de San Marcos, Facultad de Química e Ingeniería Química Departamento de Analisis y Diseño de Procesos Av. Venezuela sin - Ciudad Universitaria UNMSM - Lima - Peru

    2014-01-01

    lt is shown a mathematics analysis that link spirals, differential equations of second order of the Bessel function type and the oscillant systems with constant and variable frequency. lt is found that the oscillant systems are consecuents to a spiral mathematical functions and Bessel is only some of its varieties. Consequently is shown an exact solution of the Bessel equations which does l'lot require tables. The math model it is a tool which will be used to simulate oscillant phenomena with...

  1. Small oscillations via conservation of energy

    Science.gov (United States)

    Troy, Tia; Reiner, Megan; Haugen, Andrew J.; Moore, Nathan T.

    2017-11-01

    The work describes an analogy-based small oscillations analysis of a standard static equilibrium lab problem. In addition to force analysis, a potential energy function for the system is developed, and by drawing out mathematical similarities to the simple harmonic oscillator, we are able to describe (and experimentally verify) the period of small oscillations about the static equilibrium state. The problem was developed and implemented in a standard University Physics course at Winona State University.

  2. Q-oscillators and relativistic position operators

    Energy Technology Data Exchange (ETDEWEB)

    Arik, M. (Dept. of Mathematics, Istanbul Technical Univ. (Turkey)); Mungan, M. (Dept. of Physics, Bogazici Univ., Istanbul (Turkey))

    1992-05-21

    We investigate the multi-dimensional q-oscillator whose commutation relations are invariant under the quantum group. The no-interaction limit corresponds to a contraction of the q-oscillator algebra and yields relativistic position operators which can be expressed in terms of the generators of the Poincare group. This leads to the interpretation of the interacting q-oscillator as an relativistic quantum system and results in a hamiltonian whose spectrum is exactly exponential. (orig.).

  3. Toward precision study of atmospheric neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Kajita, Takaaki [Research Center for Cosmic Neutrinos, Institute for Cosmic Ray Research, Univ. of Tokyo, Kashiwa-no-ha 5-1-5, Kashiwa, Chiba 277-8582 (Japan)

    2006-09-15

    Atmospheric neutrinos have been playing a major role in studying neutrino oscillations. Because of the unique feature of atmospheric neutrinos, future atmospheric neutrino experiments are likely to contribute to precision studies of neutrino oscillations. Possible contribution of future atmospheric neutrino experiments to the neutrino oscillation physics are discussed, including the measurements of {theta}{sub 13}, the sign of {delta}m{sub 23}{sup 2}, the determination of octant of {theta}{sub 23} and possibly the CP phase.

  4. Sustainable agriculture - selected papers

    OpenAIRE

    Krasowicz, Stanisław; Wrzaszcz, Wioletta; Zegar, Jozef St.

    2007-01-01

    The concept of research on socially sustainable agriculture. Features of sustainable agriculture. Sustainability of private farms in the light of selected criteria. Subsistence agricultural holdings and the sustainable development of agriculture. Sustainable farms in the light of the FADN data. Description of organic holdings in Poland.

  5. Spinning Photons and Twisting Oscillators

    Science.gov (United States)

    Shi, Hao

    2014-05-01

    Optomechanics is the study of the interaction between optical radiation and mechanical motion. Typically, an optomechanical system is composed of an optical resonator coupled to a mechanical degree of freedom. Some of the most striking experimental achievements include the quantum ground state preparation for a macroscopic oscillator, the detection of optomechanical quantum back-action, and generation of optomechanically induced transparency and slow light. Most optomechanical systems depend on linear coupling between the optical field and the displacement of the mechanical oscillator. In this talk, I will start instead by discussing the basic quantum mechanics of a generic quadratically coupled optomechanical system, followed by our efforts towards extending optomechanics to torsional and rotational systems. Specifically, I will describe our theoretical proposal to couple a windmill-shaped dielectric to cavity Laguerre Gaussian modes. In addition, I will present an optoacoustic system, composed of a LG mode coupled t surface acoustic waves of a spherical mirror, as a new platform for storage of photons carrying orbital angular momentum. Finally, I will discuss our most recent investigation of the prospects of cooling full rotational motion to the quantum regime.

  6. 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.

  7. Microdroplet oscillations during optical pulling

    Science.gov (United States)

    Ellingsen, Simen A.˚.

    2012-02-01

    It was recently shown theoretically that it is possible to pull a spherical dielectric body towards the source of a laser beam [J. Chen, J. Ng, Z. Lin, and C. T. Chan, "Optical pulling force," Nat. Photonics 5, 531 (2011)], a result with immediate consequences to optical manipulation of small droplets. Optical pulling can be realized, 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 ratio 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.

  8. Nonlinear nanomechanical oscillators for ultrasensitive inertial detection

    Science.gov (United States)

    Datskos, Panagiotis George; Lavrik, Nickolay V

    2013-08-13

    A system for ultrasensitive mass and/or force detection of this invention includes a mechanical oscillator driven to oscillate in a nonlinear regime. The mechanical oscillator includes a piezoelectric base with at least one cantilever resonator etched into the piezoelectric base. The cantilever resonator is preferably a nonlinear resonator which is driven to oscillate with a frequency and an amplitude. The system of this invention detects an amplitude collapse of the cantilever resonator at a bifurcation frequency as the cantilever resonator stimulated over a frequency range. As mass and/or force is introduced to the cantilever resonator, the bifurcation frequency shifts along a frequency axis in proportion to the added mass.

  9. Introduction to classical and quantum harmonic oscillators

    CERN Document Server

    Bloch, Sylvan C

    2013-01-01

    From conch shells to lasers . harmonic oscillators, the timeless scientific phenomenon As intriguing to Galileo as they are to scientists today, harmonic oscillators have provided a simple and compelling paradigm for understanding the complexities that underlie some of nature's and mankind's most fascinating creations. From early string and wind instruments fashioned from bows and seashells to the intense precision of lasers, harmonic oscillators have existed in various forms, as objects of beauty and scientific use. And harmonic oscillation has endured as one of science's most fascinating con

  10. High Reliability Oscillators for Terahertz Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Terahertz sources based on lower frequency oscillators and amplifiers plus a chain of frequency multipliers are the workhorse technology for NASA's terahertz...

  11. Waves and oscillations in nature an introduction

    CERN Document Server

    Narayanan, A Satya

    2015-01-01

    Waves and oscillations are found in large scales (galactic) and microscopic scales (neutrino) in nature. Their dynamics and behavior heavily depend on the type of medium through which they propagate.Waves and Oscillations in Nature: An Introduction clearly elucidates the dynamics and behavior of waves and oscillations in various mediums. It presents different types of waves and oscillations that can be observed and studied from macroscopic to microscopic scales. The book provides a thorough introduction for researchers and graduate students in assorted areas of physics, such as fluid dynamics,

  12. Stochastic Kuramoto oscillators with discrete phase states

    Science.gov (United States)

    Jörg, David J.

    2017-09-01

    We present a generalization of the Kuramoto phase oscillator model in which phases advance in discrete phase increments through Poisson processes, rendering both intrinsic oscillations and coupling inherently stochastic. We study the effects of phase discretization on the synchronization and precision properties of the coupled system both analytically and numerically. Remarkably, many key observables such as the steady-state synchrony and the quality of oscillations show distinct extrema while converging to the classical Kuramoto model in the limit of a continuous phase. The phase-discretized model provides a general framework for coupled oscillations in a Markov chain setting.

  13. 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.

  14. Sustainable NREL - Site Sustainability Plan FY 2015

    Energy Technology Data Exchange (ETDEWEB)

    None, None

    2015-01-01

    NREL's Site Sustainability Plan FY 2015 reports on sustainability plans for the lab for the year 2015 based on Executive Order Goals and provides the status on planned actions cited in the FY 2014 report.

  15. A coupled-oscillator model of olfactory bulb gamma oscillations.

    Directory of Open Access Journals (Sweden)

    Guoshi Li

    2017-11-01

    Full Text Available The olfactory bulb transforms not only the information content of the primary sensory representation, but also its underlying coding metric. High-variance, slow-timescale primary odor representations are transformed by bulbar circuitry into secondary representations based on principal neuron spike patterns that are tightly regulated in time. This emergent fast timescale for signaling is reflected in gamma-band local field potentials, presumably serving to efficiently integrate olfactory sensory information into the temporally regulated information networks of the central nervous system. To understand this transformation and its integration with interareal coordination mechanisms requires that we understand its fundamental dynamical principles. Using a biophysically explicit, multiscale model of olfactory bulb circuitry, we here demonstrate that an inhibition-coupled intrinsic oscillator framework, pyramidal resonance interneuron network gamma (PRING, best captures the diversity of physiological properties exhibited by the olfactory bulb. Most importantly, these properties include global zero-phase synchronization in the gamma band, the phase-restriction of informative spikes in principal neurons with respect to this common clock, and the robustness of this synchronous oscillatory regime to multiple challenging conditions observed in the biological system. These conditions include substantial heterogeneities in afferent activation levels and excitatory synaptic weights, high levels of uncorrelated background activity among principal neurons, and spike frequencies in both principal neurons and interneurons that are irregular in time and much lower than the gamma frequency. This coupled cellular oscillator architecture permits stable and replicable ensemble responses to diverse sensory stimuli under various external conditions as well as to changes in network parameters arising from learning-dependent synaptic plasticity.

  16. Sustainability in Transport Planning

    DEFF Research Database (Denmark)

    Gudmundsson, Henrik; Greve, Carsten

    Contribution to session J: Joint University Sustainability Initiatives. This session will provide an inspiring overview of interdisciplinary research and teaching activities on sustainability bridging DTU, KU, and CBS, and introduce the joint collaboration Copenhagen Sustainability Initiative (COSI...

  17. Sustainability : Politics and governance

    NARCIS (Netherlands)

    Heinrichs, Harald; Biermann, Frank

    2016-01-01

    he article gives an overview of global sustainability policy and politics. It is shown how international policy making on sustainable development has progressed from environmental policy toward recent approaches of Earth system governance. Key challenges of international sustainability politics are

  18. Textiles and clothing sustainability sustainable technologies

    CERN Document Server

    2017-01-01

    This is the first book to deal with the innovative technologies in the field of textiles and clothing sustainability. It details a number of sustainable and innovative technologies and highlights their implications in the clothing sector. There are currently various measures to achieve sustainability in the textiles and the clothing industry, including innovations in the manufacturing stage, which is the crux of this book.

  19. FUNDAMENTAL AREAS OF PHENOMENOLOGY (INCLUDING APPLICATIONS): Mechanism of Current Oscillations in Gallium Arsenide Photoconductive Semiconductor Switches

    Science.gov (United States)

    Tian, Li-Qiang; Shi, Wei

    2008-07-01

    Semi-insulating photoconductive semiconductor switch with an electrode gap of 4 mm, triggered by a laser pulse with energy of 0.5mJ, and applied bias of 2.5kV, the periodicity current oscillation with a cycle of 12ns is obtained. It is indicated that the current oscillation is one mode of transferred electron effect, namely quenched domain mode. This mode of trans-electron oscillator is obtained when the instantaneous bias electric field drops below the sustaining field (the minimum electric field required to support the domain) before the domain reaches the anode, which leads to the domain disappears somewhere in the bulk of the switch and away from the ohmic contacts. We mainly analyse the time-dependent characteristic of the mode, the theoretical analysis results are in excellent agreement with the experiment.

  20. Experimental Evidence of Large Amplitude pH Mediated Autonomous Chemomechanical Oscillation

    Directory of Open Access Journals (Sweden)

    Xin Yang

    2017-10-01

    Full Text Available Large amplitude autonomous chemomechanical oscillations were observed in a coupled system consisting of a porous pH-responsive hydrogel and a bromate-sulfite-manganese (II pH oscillatory reaction. The porous structure effectively improves the chemomechanical response speed, and the negative feedback species of the bulk oscillation Mn2+ takes part in the coupling by forming complex and physical crosslinks with the responsive group in the gel. It strengthens the porous gel by forming additional networks, which may contribute to sustaining the long-lasting chemomechanical oscillation. Additionally, the interaction between Mn2+ and the hydrogel alters the period of the oscillatory reaction due to its binding competition with H+, the positive feedback species.

  1. 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.

  2. Signal velocity in oscillator arrays

    Science.gov (United States)

    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.

  3. Oscillating spin-2 dark matter

    Science.gov (United States)

    Marzola, Luca; Raidal, Martti; Urban, Federico R.

    2018-01-01

    The negative outcomes of laboratory searches, juxtaposed with cosmological observations, may indicate that dark matter has a gravitational origin. We show that coherent oscillations of a massive spin-2 field emerging from bimetric theory can easily account for the observed dark matter abundance. The framework, based on the only known consistent extension of general relativity to interacting spin-2 fields, is testable in precision measurements of the electric charge variation by means of atomic clocks, molecular systems, dedicated resonant mass detectors, as well as gravity interferometers and axionlike-particle experiments. These searches, therefore, provide a new window into the phenomenology of gravity which complements the results of dedicated tests of gravitation. We also present a multimetric extension of the scenario that straightforwardly implements the clockwork mechanism for gravity, explaining the apparent weakness of this force.

  4. Analysing Biochemical Oscillations through Probabilistic Model Checking

    DEFF Research Database (Denmark)

    Ballarini, Paolo; Mardare, Radu Iulian; Mura, Ivan

    2009-01-01

    Analysing Biochemical Oscillations through Probabilistic Model Checking. In Proc. of the Second International Workshop "From Biology To Concurrency" (FBTC 2008), Electronic Notes in Theoretical Computer Science......Analysing Biochemical Oscillations through Probabilistic Model Checking. In Proc. of the Second International Workshop "From Biology To Concurrency" (FBTC 2008), Electronic Notes in Theoretical Computer Science...

  5. 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....

  6. Stabilizing oscillating universes against quantum decay

    Science.gov (United States)

    Mithani, Audrey T.; Vilenkin, Alexander

    2015-07-01

    We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states.

  7. Neutrino mass and oscillation: An introductory review

    Indian Academy of Sciences (India)

    tion to the atmospheric and solar neutrino oscillation data requires only two right handed singlet neutrinos. 2. Neutrino mixing and oscillation (vacuum). If the neutrinos have nonzero mass, there will in general be mixing between the neutrino species as in the case of quarks. For most practical applications it is adequate to ...

  8. Chaos in nonlinear oscillations controlling and synchronization

    CERN Document Server

    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.

  9. Stabilizing oscillating universes against quantum decay

    Energy Technology Data Exchange (ETDEWEB)

    Mithani, Audrey T.; Vilenkin, Alexander [Institute of Cosmology, Department of Physics and Astronomy,Tufts University, Medford, MA 02155 (United States)

    2015-07-07

    We investigate the effect of vacuum corrections, due to the trace anomaly and Casimir effect, on the stability of an oscillating universe with respect to decay by tunneling to the singularity. We find that these corrections do not generally stabilize an oscillating universe. However, stability may be achieved for some specially fine-tuned non-vacuum states.

  10. Vibrational resonance in the Morse oscillator

    Indian Academy of Sciences (India)

    Abstract. The occurrence of vibrational resonance is investigated in both classical and quantum mechanical Morse oscillators driven by a biharmonic force. The biharmonic force consists of two forces of widely different frequencies ω and with. ≫ ω. In the damped and biharmoni- cally driven classical Morse oscillator, ...

  11. Effective harmonic oscillator description of anharmonic molecular ...

    Indian Academy of Sciences (India)

    ... a harmonic oscillator eigenfunction with the centroid and width parameter as variational paraeters. It is found that the effective harmonic oscillator approximation provides a description of the anharmonic eigenstates very similar to the vibrational self consistent field results. Coriolis coupling is also included in these studies.

  12. Neutrino oscillations: Present status and outlook

    Indian Academy of Sciences (India)

    The status of sterile neutrino oscillation interpretations of the LSND anomaly in the light of recent MiniBooNE results is also discussed. Further-more, an outlook on the measurement of the mixing angle 13 in the near term future, as well as prospects to discover CP violation in neutrino oscillations and to determine the type ...

  13. Effective harmonic oscillator description of anharmonic molecular ...

    Indian Academy of Sciences (India)

    Administrator

    Abstract. The validity of an effective harmonic oscillator approximation for anharmonic molecular vibrations is tested and compared with vibrational self consistent field and vibrational configurational interaction results. The effective harmonic oscillator is constructed variationally, by taking the trial wave function as a harmonic ...

  14. Discontinuous Spirals of Stable Periodic Oscillations

    DEFF Research Database (Denmark)

    Sack, Achim; Freire, Joana G.; Lindberg, Erik

    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...

  15. The 2D κ-Dirac oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Fabiano M., E-mail: fmandrade@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa-PR (Brazil); Silva, Edilberto O., E-mail: edilbertoo@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís-MA (Brazil)

    2014-11-10

    In this Letter, 2D Dirac oscillator in the quantum deformed framework generated by the κ-Poincaré–Hopf algebra is considered. The problem is formulated using the κ-deformed Dirac equation. The resulting theory reveals that the energies and wave functions of the oscillator are modified by the deformation parameter.

  16. In plane oscillation of a bifilar pendulum

    Science.gov (United States)

    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.

  17. 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...

  18. Neutrino oscillations: Present status and outlook

    Indian Academy of Sciences (India)

    more, an outlook on the measurement of the mixing angle θ13 in the near term future, as well as prospects to discover CP violation in neutrino oscillations and to determine the type of the neutrino mass ordering by long-baseline experiments in the long term future are given. Keyword. Neutrino oscillations. PACS Nos 14.60.

  19. Small Oscillations via Conservation of Energy

    Science.gov (United States)

    Troy, Tia; Reiner, Megan; Haugen, Andrew J.; Moore, Nathan T.

    2017-01-01

    The work describes an analogy-based small oscillations analysis of a standard static equilibrium lab problem. In addition to force analysis, a potential energy function for the system is developed, and by drawing out mathematical similarities to the simple harmonic oscillator, we are able to describe (and experimentally verify) the period of small…

  20. Oscillations of first order difference equations

    Indian Academy of Sciences (India)

    Oscillations of first order difference equations. N PARHI. Department of Mathematics, Berhampur University, Berhampur 760 007, India. MS received 10 June 1999; revised 28 December 1999. Abstract. The oscillatory and asymptotic behaviour of solutions of first order diff- erence equations is studied. Keywords. Oscillation ...

  1. Teaching Oscillations by a Model of Nanoresonator

    Science.gov (United States)

    Lindell, A.; Viiri, J.

    2009-01-01

    Nanoscience offers fascinating opportunities for science education as it links the achievements of modern technology to traditional models of science. In this article we present a nanotechnology orientated lesson on oscillations, suitable for physics courses at high schools and universities. The focus of the lesson is in forced oscillations on a…

  2. Oscillator clustering in a resource distribution chain

    DEFF Research Database (Denmark)

    Postnov, D.; Sosnovtseva, Olga; Mosekilde, Erik

    2005-01-01

    separate the inherent dynamics of the individual oscillator from the properties of the coupling network. Illustrated by examples from microbiological population dynamics, renal physiology, and electronic oscillator theory, we show how competition for primary resources in a resource distribution chain leads...

  3. 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...

  4. 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...

  5. Surface plasmon excitation by a quantum oscillator

    OpenAIRE

    Lidsky, V. V.

    2009-01-01

    Surface waves in a thin uniform metal film are described in terms of quantum electrodynamics.The interaction of surface waves with a quantum oscillator is discussed in the dipole approximation. The increase in the spontaneous emission rate of the excited quantum oscillator, the so called Purcell factor, is evaluated to be as high as by 10 to the five times.

  6. Chemical sensor with oscillating cantilevered probe

    Science.gov (United States)

    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.

  7. New neutrino oscillation results from NOVA

    CERN Multimedia

    CERN. Geneva

    2018-01-01

    Neutrinos oscillate among flavors as they travel because a neutrino of a particular flavor is also a superposition of multiple neutrinos with slightly different masses.  The interferometric nature of oscillations allows these tiny mass differences to be measured, along with the parameters of the PMNS matrix which governs the mixing. However, since neutrinos only interact weakly, a powerful neutrino source and massive detectors are required to measure them. In this talk I will show recently updated results from NOvA, a long-baseline neutrino oscillation experiment at Fermilab with two functionally identical scintillator detectors. I will present measurements of muon neutrino disappearance and electron neutrino appearance, and what constraints those measurements put on the remaining open questions in neutrino oscillations: Is the neutrino mass hierarchy "normal" or "inverted?" Do neutrino oscillations violate CP symmetry? Is the mixing in the atmospheric sector maximal? The recent update includes 50%...

  8. Is the quadrature oscillator a multivibrator?

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2004-01-01

    The aim of this article is to give insight into the mechanisms behind the behavior of oscillators from a new angle, introducing the idea of "frozen eigenvalues". This approach is based on piecewise-linear modelling and a study of the eigenvalues of the time varying linearized Jacobian of the nonl......The aim of this article is to give insight into the mechanisms behind the behavior of oscillators from a new angle, introducing the idea of "frozen eigenvalues". This approach is based on piecewise-linear modelling and a study of the eigenvalues of the time varying linearized Jacobian...... of the nonlinear differential equations describing the oscillator. A multivibrator and a quadrature oscillator are used as test examples. The mechanisms behind the oscillations of the two circuits are compared....

  9. Improved memristor-based relaxation oscillator

    KAUST Repository

    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.

  10. 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.

  11. 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.

  12. Atmospheric neutrino oscillations for Earth tomography

    Science.gov (United States)

    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.

  13. Geometric phase shifts in biological oscillators.

    Science.gov (United States)

    Tourigny, David S

    2014-08-21

    Many intracellular processes continue to oscillate during the cell cycle. Although it is not well-understood how they are affected by discontinuities in the cellular environment, the general assumption is that oscillations remain robust provided the period of cell divisions is much larger than the period of the oscillator. Here, I will show that under these conditions a cell will in fact have to correct for an additional quantity added to the phase of oscillation upon every repetition of the cell cycle. The resulting phase shift is an analogue of the geometric phase, a curious entity first discovered in quantum mechanics. In this letter, I will discuss the theory of the geometric phase shift and demonstrate its relevance to biological oscillations. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. Global dynamics of a stochastic neuronal oscillator

    Science.gov (United States)

    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.

  15. Assessing sustainable remediation frameworks using sustainability principles.

    Science.gov (United States)

    Ridsdale, D Reanne; Noble, Bram F

    2016-12-15

    The remediation industry has grown exponentially in recent decades. International organizations of practitioners and remediation experts have developed several frameworks for integrating sustainability into remediation projects; however, there has been limited attention to how sustainability is approached and operationalized in sustainable remediation frameworks and practices - or whether sustainability plays any meaningful role at all in sustainable remediation. This paper examines how sustainability is represented in remediation frameworks and the guidance provided for practical application. Seven broad sustainability principles and review criteria are proposed and applied to a sample of six international remediation frameworks. Not all review criteria were equally satisfied and none of the frameworks fully met all criteria; however, the best performing frameworks were those identified as sustainability remediation frameworks. Intra-generational equity was addressed by all frameworks. Integrating social, economic and biophysical components beyond triple-bottom-line indicators was explicitly addressed only by the sustainable remediation frameworks. No frameworks provided principle- or rule-based guidance for dealing with trade-offs in sustainability decisions. Copyright © 2016 Elsevier Ltd. All rights reserved.

  16. Organizing for Sustainability

    Science.gov (United States)

    Brown, William M.; Hamburger, Michael W.

    2012-01-01

    A successful campus sustainability effort catalyzes broad engagement of the campus community and integration of sustainability principles into the academic and operational components of campus life. Although many universities have embraced sustainability as a new core value, others have been more sluggish in adopting sustainability principles to…

  17. Technology and sustainability

    NARCIS (Netherlands)

    Kroeze, C.; Boersema, J.J.; Tellegen, E.; Cremers, A.

    2011-01-01

    In ten essays, this book addresses a broad range of issues related to the interplay of sustainability and technology. How do population growth and technology relate to sustainable development? Can globalization be reconciled with sustainable development? Is sustainability a subjective or an

  18. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    by analysing processes of social learning. The book addresses the need to move towards sustainability at societal level as a democratic challenge questioning the way we live on planet earth. By conceptualising sustain-ability as an immanent and emergent ability of ecological and social life, continuously...... to renew itself without eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming...

  19. Sustainable Investment. Literature Overview

    Energy Technology Data Exchange (ETDEWEB)

    Weda, J.; Kerste, M.; Rosenboom, N.

    2010-08-15

    Corporate Social Responsibility (CSR), or sustainability at the company level, entails incorporating ecological (environmental stakeholders) and social aspects (stakeholders other than shareholders and environmental stakeholders) when doing business. Socially Responsible Investment (SRI) concerns sustainability at the investment, fund or portfolio level and involves screening the sustainability of companies before investing in them. This report highlights leading literature and empirical findings on 'sustainable investment', amongst others addressing the economic rationale for CSR and SRI. This report is part of a set of SEO-reports on finance and sustainability. The other reports deal with: Financing the Transition to Sustainable Energy; Carbon Trading; Innovations in financing environmental and social sustainability.

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

    Directory of Open Access Journals (Sweden)

    Ikuhiro Yamaguchi

    Full Text Available Time delay is known to induce sustained oscillations in many biological systems such as electroencephalogram (EEG activities and gene regulations. Furthermore, interactions among delay-induced oscillations can generate complex collective rhythms, which play important functional roles. However, due to their intrinsic infinite dimensionality, theoretical analysis of interacting delay-induced oscillations has been limited. Here, we show that the two primary methods for finite-dimensional limit cycles, namely, the center manifold reduction in the vicinity of the Hopf bifurcation and the phase reduction for weak interactions, can successfully be applied to interacting infinite-dimensional delay-induced oscillations. We systematically derive the complex Ginzburg-Landau equation and the phase equation without delay for general interaction networks. Based on the reduced low-dimensional equations, we demonstrate that diffusive (linearly attractive coupling between a pair of delay-induced oscillations can exhibit nontrivial amplitude death and multimodal phase locking. Our analysis provides unique insights into experimentally observed EEG activities such as sudden transitions among different phase-locked states and occurrence of epileptic seizures.

  1. Periodic motions and resonances of impact oscillators

    Science.gov (United States)

    Dyskin, Arcady V.; Pasternak, Elena; Pelinovsky, Efim

    2012-06-01

    Bilinear oscillators - the oscillators whose springs have different stiffnesses in compression and tension - model a wide range of phenomena. A limiting case of bilinear oscillator with infinite stiffness in compression - the impact oscillator - is studied here. We investigate a special set of impact times - the eigenset, which corresponds to the solution of the homogeneous equation, i.e. the oscillator without the driving force. We found that this set and its subsets are stable with respect to variation of initial conditions. Furthermore, amongst all periodic sets of impact times with the period commensurate with the period of driving force, the eigenset is the only one which can support resonances, in particular the multi-'harmonic' resonances. Other resonances should produce non-periodic sets of impact times. This funding indicates that the usual simplifying assumption [e.g., S.W. Shaw, P.J. Holmes, A periodically forced piecewise linear oscillator, Journal of Sound and Vibration 90 (1983) 129-155] that the times between impacts are commensurate with the period of the driving force does not always hold. We showed that for the first sub-'harmonic resonance' - the resonance achieved on a half frequency of the main resonance - the set of impact times is asymptotically close to the eigenset. The envelope of the oscillations in this resonance increases as a square root of time, opposite to the linear increase characteristic of multi-'harmonic' resonances.

  2. Temperature and state dependence of dynamic phrenic oscillations in the decerebrate juvenile rat.

    Science.gov (United States)

    Marchenko, Vitaliy; Rogers, Robert F

    2007-12-01

    The aim of the present study was to determine characteristics of fast oscillations in the juvenile rat phrenic nerve (Ph) and to establish their temperature and state dependence. Two different age-matched decerebrate, baro- and chemodenervated rat preparations, in vivo and in situ arterially perfused models, were used to examine three systemic properties: 1) generation and dynamics of fast oscillations in Ph activity (both preparations), 2) responses to anoxia (both preparations), and 3) the effects of temperature on fast oscillations (in situ only). Both juvenile preparations generated power and coherence in two major bands analogous to adult medium- and high-frequency oscillations (HFO) at frequencies that increased with temperature but were lower than in adults. At < 28 degrees C, however, Ph oscillations were confined primarily to one low-frequency band (20-45 Hz). During sustained anoxia, both preparations produced stereotypical state changes from eupnea to hyperpnea to transition bursting (a behavior present only in vivo during incomplete ischemia) to gasping. Thus the juvenile rat produces a sequential pattern of responses to anoxia that are intermediate forms between those produced by neonates and those produced by adults. Time-frequency analysis determined that fast oscillations demonstrated dynamics over the course of the inspiratory burst and a state dependence similar to that of adults in vivo in which hyperpnea (and transition) bursts are associated with increases in HFO, while gasping contains no HFO. Our results confirm that both the fast oscillations in Ph activity and the coherence between Ph pairs produced by the juvenile rat are profoundly state- and temperature-dependent.

  3. Spatiotemporal Patterns of an Evoked Network Oscillation in Neocortical Slices: Coupled Local Oscillators

    Science.gov (United States)

    Bai, Li; Huang, Xiaoying; Yang, Qian; Wu, Jian-young

    2015-01-01

    We have discovered an evoked network oscillation in rat neocortical slices and have examined its spatiotemporal patterns with voltage sensitive dye imaging. The slices (visual and auditory cortices) were prepared in a medium of low calcium, high magnesium and with sodium replaced by choline in order to reduce the excito-toxicity and sodium loading. After slicing, the choline was washed out while normal calcium, magnesium and sodium concentrations were restored. The oscillation was evoked by a single electrical shock to slices bathed in normal artificial cerebral spinal fluid (ACSF). The oscillation was organized as an all-or-none epoch containing 4 to 13 cycles at a central frequency around 25 Hz. The activity can be reversibly blocked by CNQX, APV and atropine, but not by bicuculline, indicating poly-synaptic excitatory mechanisms. Voltage sensitive dye imaging showed high amplitude oscillation signals in superficial and middle cortical layers. Spatiotemporally, the oscillations were organized as waves, propagating horizontally along cortical laminar. Each oscillation cycle was associated with one wave propagating in space. The waveforms were often different at different locations (e.g., extra cycles), suggesting the co-existence of multiple local oscillators. For different cycles, the waves often initiated at different locations, suggesting that local oscillators are competing to initiate each oscillation cycle. Overall our results suggest that this cortical network oscillation is organized at two levels: locally, oscillating neurons are tightly coupled to form local oscillators, and globally the coupling between local oscillators is weak, allowing abrupt spatial phase lags and propagating waves with multiple initiation sites. PMID:16870836

  4. Oscillation in Evolution of Cooperation for Addressing Climate Change

    Science.gov (United States)

    Wang, Yuan-Feng; Li, Ke-Ping; Zhang, Peng-Fei

    2011-05-01

    Climate protection is a problem of sustaining a public resource. All countries of the world should take action to deal with climate change. However, such an action is actually a game process where each country chooses to cooperate or defect under constrained condition. Here we study the group behavior of countries in dealing with climate change. In our study, the countries of the world are considered as players who are distributed on an assumed spatial network. A new evolution rule is proposed to model the game process among the players. Our extensive experiments demonstrate that under constrained condition, the local psychology of players possibly results in the formation of local group. Some local and global oscillations can be found where part or all of the players change their choices periodically.

  5. Oscillating and rotating sine-Gordon system

    DEFF Research Database (Denmark)

    Olsen, O. H.; Samuelsen, Mogens Rugholm

    1986-01-01

    The interaction between a 2π kink and the background or vacuum is investigated in the pure sine-Gordon system. For an oscillating background (i.e., the k=0 part of the phonon spectrum) the 2π kink oscillates, while for increasing or decreasing vacuum two phenomena have been observed, depending...... on the rate of change of the vacuum. For small rates a parametric excitation of standing waves is found, and for larger rates the system linearizes. In the case of oscillating vacuum a perturbation approach explains the behavior perfectly, while for small rates of increasing vacuum the system reduces...

  6. Oscillators - an approach for a better understanding

    DEFF Research Database (Denmark)

    Lindberg, Erik

    2003-01-01

    The aim of this tutorial is to provide an electronic engineer knowledge and insight for a better understanding of the mechanisms behind the behaviour of electronic oscillators. A linear oscillator is a mathematical fiction which can only be used as a starting point for the design of a real...... oscillator based on the Barkhausen criteria. Statements in textbooks and papers saying that the nonlinearities are bringing back the poles to the imaginary axis are wrong. The concept of "frozen eigenvalues" is introduced by means of piece-wise-linear modelling of the nonlinear components which are necessary...

  7. Phase Multistability in Coupled Oscillator Systems

    DEFF Research Database (Denmark)

    Mosekilde, Erik; Postnov, D.E.; Sosnovtseva, Olga

    2003-01-01

    The phenomenon of phase multistability arises in connection with the synchronization of coupled oscillator systems when the systems individually display complex wave forms associated, for instance, with the presence of subharmonic components or with significant variations of the phase velocity...... along the orbit of the individual oscillator. Focusing on the mechanisms underlying the appearance of phase multistability, the paper examines a variety of phase-locked patterns. In particular we demonstrate the nested structure of synchronization regions for oscillations with multicrest wave forms...... and investigate how the number of spikes per train and the proximity of a neighboring equilibrium point can influence the formation of coexisting regimes in coupled bursters....

  8. Possible solar modulation of pacific decadal oscillation

    Science.gov (United States)

    Ma, Lihua; Yin, Zhiqiang

    2017-09-01

    The Pacific Decadal Oscillation (PDO) is an El Niño-like pattern of Pacific climate variability, oscillating between its warm and cool phase about every 20-30 years as defined by oceanic temperature anomalies in the northeast and tropical Pacific Ocean. In this work, the authors investigate the possible connection between the PDO and solar activity by means of wavelet technique. The study shows obvious fluctuation characteristics in the PDO series. The modulation action from solar activity plays an important role in the oscillation of the Pacific, and there is a possible association existing in the PDO and solar activity on decade time scales.

  9. Relativistic quantum mechanics of a Dirac oscillator

    CERN Document Server

    Martines y Romero, R P; Salas-Brito, A L

    1995-01-01

    The Dirac oscillator is an exactly soluble model recently introduced in the context of many particle models in relativistic quantum mechanics. The model has been also considered as an interaction term for modelling quark confinement in quantum chromodynamics. These considerations should be enough for demonstrating that the Dirac oscillator can be an excellent example in relativistic quantum mechanics. In this paper we offer a solution to the problem and discuss some of its properties. We also discuss a physical picture for the Dirac oscillator's non-standard interaction, showing how it arises on describing the behaviour of a neutral particle carrying an anomalous magnetic moment and moving inside a uniformly charged sphere. (author)

  10. Damping of Crank–Nicolson error oscillations

    DEFF Research Database (Denmark)

    Britz, Dieter; Østerby, Ole; Strutwolf, J.

    2003-01-01

    The Crank–Nicolson (CN) simulation method has an oscillatory response to sharp initial transients. The technique is convenient but the oscillations make it less popular. Several ways of damping the oscillations in two types of electrochemical computations are investigated. For a simple one...... be computationally more expensive with some systems. The simple device of starting with one backward implicit (BI, or Laasonen) step does damp the oscillations, but not always sufficiently. For electrochemical microdisk simulations which are two-dimensional in space and using CN, the use of a first BI step is much...

  11. Oscillating magnetocaloric effect of a multilayer graphene

    Energy Technology Data Exchange (ETDEWEB)

    Alisultanov, Z. Z., E-mail: zaur0102@gmail.com [Amirkhanov Institute of Physics, Russian Academy of Sciences, Dagestan Science Centre, Makhachkala (Russian Federation); Prokhorov General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Dagestan State University, Makhachkala (Russian Federation); Paixão, L. S.; Reis, M. S. [Instituto de Física, Universidade Federal Fluminense, Av. Gal. Milton Tavares de Souza s/n, 24210-346 Niterói, RJ (Brazil)

    2014-12-08

    The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.

  12. Oscillating magnetocaloric effect of a multilayer graphene

    Science.gov (United States)

    Alisultanov, Z. Z.; Paixão, L. S.; Reis, M. S.

    2014-12-01

    The oscillating magnetocaloric effect of a multilayer graphene in Bernal and rhombohedral stacking is investigated to extend the previous knowledge of the effect on a single layer graphene. We started from results of a tight-binding model and obtained analytical expressions for the thermodynamic potential and for the entropy change. The last exhibits the same dependence on field and temperature observed for other diamagnetic systems; it oscillates with the inverse magnetic field and presents a maximum value at a given temperature. The amplitude of the oscillating entropy change decreases with the number of layers and the stacking sequence rules the magnetocaloric properties of the system.

  13. Compact heterodyne NEMS oscillator for sensing applications

    Science.gov (United States)

    Sansa, Marc; Gourlat, Guillaume; Jourdan, Guillaume; Gely, Marc; Villard, Patrick; Sicard, Gilles; Hentz, Sébastien

    2016-11-01

    We present a novel topology of heterodyne nanoelectromechanical self-oscillator, aimed at the dense integration of resonator arrays for sensing applications. This oscillator is based on an original measurement method, suitable for both open loop and closed loop operations, which simplifies current down-mixing set-ups. When implemented on-chip, it will allow the reduction of the size and power consumption of readout CMOS circuitry. This is today the limiting factor for the integration density of NEMS oscillators for real-life applications. Here we characterize this method in both open-loop and closed-loop, and evaluate its frequency stability.

  14. Oscillations in glycolysis in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Kloster, Antonina; Olsen, Lars Folke

    2012-01-01

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

  15. Synchronization of tubular pressure oscillations in interacting nephrons

    Energy Technology Data Exchange (ETDEWEB)

    Sosnovtseva, O.V. E-mail: olga@fysik.dtu.dk; Postnov, D.E.; Mosekilde, E.; Holstein-Rathlou, N.-H

    2003-01-01

    The pressure and flow regulation in the individual functional unit of the kidney (the nephron) tends to operate in an unstable regime. For normal rats, the regulation displays regular self-sustained oscillations, but for rats with high blood pressure the oscillations become chaotic. We explain the mechanisms responsible for this behavior and discuss the involved bifurcations. Experimental data show that neighboring nephrons adjust their pressure and flow regulation in accordance with one another. For rats with normal blood pressure, in-phase as well as anti-phase synchronization can be observed. For spontaneously hypertensive rats, indications of chaotic phase synchronization are found. Accounting for a hermodynamics as well as for a vascular coupling between nephrons that share a common interlobular artery, we present a model of the interaction of the pressure and flow regulations between adjacent nephrons. It is shown that this model, with physiologically realistic parameter values, can reproduce the different types of experimentally observed synchronization, including multistability and partial phase synchronization with respect to the slow and fast dynamics.

  16. Recurrent jellyfish blooms are a consequence of global oscillations.

    Science.gov (United States)

    Condon, Robert H; Duarte, Carlos M; Pitt, Kylie A; Robinson, Kelly L; Lucas, Cathy H; Sutherland, Kelly R; Mianzan, Hermes W; Bogeberg, Molly; Purcell, Jennifer E; Decker, Mary Beth; Uye, Shin-ichi; Madin, Laurence P; Brodeur, Richard D; Haddock, Steven H D; Malej, Alenka; Parry, Gregory D; Eriksen, Elena; Quiñones, Javier; Acha, Marcelo; Harvey, Michel; Arthur, James M; Graham, William M

    2013-01-15

    A perceived recent increase in global jellyfish abundance has been portrayed as a symptom of degraded oceans. This perception is based primarily on a few case studies and anecdotal evidence, but a formal analysis of global temporal trends in jellyfish populations has been missing. Here, we analyze all available long-term datasets on changes in jellyfish abundance across multiple coastal stations, using linear and logistic mixed models and effect-size analysis to show that there is no robust evidence for a global increase in jellyfish. Although there has been a small linear increase in jellyfish since the 1970s, this trend was unsubstantiated by effect-size analysis that showed no difference in the proportion of increasing vs. decreasing jellyfish populations over all time periods examined. Rather, the strongest nonrandom trend indicated jellyfish populations undergo larger, worldwide oscillations with an approximate 20-y periodicity, including a rising phase during the 1990s that contributed to the perception of a global increase in jellyfish abundance. Sustained monitoring is required over the next decade to elucidate with statistical confidence whether the weak increasing linear trend in jellyfish after 1970 is an actual shift in the baseline or part of an oscillation. Irrespective of the nature of increase, given the potential damage posed by jellyfish blooms to fisheries, tourism, and other human industries, our findings foretell recurrent phases of rise and fall in jellyfish populations that society should be prepared to face.

  17. Energy harvesting through flow-induced oscillations of a foil

    Science.gov (United States)

    Peng, Zhangli; Zhu, Qiang

    2009-12-01

    By using a Navier-Stokes model, we examine a novel flow energy harvesting device consisting of a flapping foil mounted on a damper (representing the power generator) and a rotational spring. Self-induced and self-sustained flapping motions, including a heaving motion h(t ) and a pitching motion α(t ), are excited by an incoming flow and power extraction is achieved from the heaving response. Depending upon the configuration of the system and the mechanical parameters (e.g., the location of the pitching axis and the stiffness of the rotational spring), four different responses are recorded: (i) the foil remains stable in its initial position (α =0 and h =0); (ii) periodic pitching (around α =0) and heaving motions are excited; (iii) the foil undergoes irregular motions characterized by switching between oscillations around two pitching angles; and (iv) the foil rotates to a position with an angle to the incoming flow and oscillates around it. The existence of response (ii) suggests the feasibility of controllable and stable flow energy extraction by this device. Through numerical simulations with a Navier-Stokes model we have determined combinations of geometric and mechanical parameters to achieve this response. The corresponding energy harvesting capacity and efficiency are predicted.

  18. Polaritonic Rabi and Josephson Oscillations.

    Science.gov (United States)

    Rahmani, Amir; Laussy, Fabrice P

    2016-07-25

    The dynamics of coupled condensates is a wide-encompassing problem with relevance to superconductors, BECs in traps, superfluids, etc. Here, we provide a unified picture of this fundamental problem that includes i) detuning of the free energies, ii) different self-interaction strengths and iii) finite lifetime of the modes. At such, this is particularly relevant for the dynamics of polaritons, both for their internal dynamics between their light and matter constituents, as well as for the more conventional dynamics of two spatially separated condensates. Polaritons are short-lived, interact only through their material fraction and are easily detuned. At such, they bring several variations to their atomic counterpart. We show that the combination of these parameters results in important twists to the phenomenology of the Josephson effect, such as the behaviour of the relative phase (running or oscillating) or the occurence of self-trapping. We undertake a comprehensive stability analysis of the fixed points on a normalized Bloch sphere, that allows us to provide a generalized criterion to identify the Rabi and Josephson regimes in presence of detuning and decay.

  19. Torsional oscillations of strange stars

    Directory of Open Access Journals (Sweden)

    Mannarelli Massimo

    2014-01-01

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

  20. Recherche des oscillations de Neutrinos $\

    CERN Document Server

    Gangler, E

    1997-01-01

    Le detecteur nomad, place sur le faisceau de neutrinos wide-band-beam du sps, de contamination en neutrino tau marginale, permet de rechercher des oscillations neutrino muon - tau dans la region de pertinence cosmologique et de distinguer statistiquement les courants charges des neutrinos tau essentiellement par leur mesure cinematique. Une large part du travail de these a donc ete consacree a la reconstruction des evenements dans les chambres a derive, cible instrumentee et cur de l'experience, dont la physique de detection est decrite. Une methode de recherche de traces fut developpee, utilisant certaines informations d'un autre sous-detecteur de nomad, le trd. Pour combler une perte d'efficacite de reconstruction, une methode de recherche de traces courtes s'appuyant sur des vertex deja constitues fut developpee en exploitant les potentialites du filtre de kalman, algorithme iteratif d'ajustement de traces. Ces methodes sont utilisees en production par la collaboration. Cette these porte sur la recherche d...

  1. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    How can action research further new research orientations towards sustainability? This book, empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating on urban sustainability, answers this question...... by analysing processes of social learning. The book addresses the need to move towards sustainability at societal level as a democratic challenge questioning the way we live on planet earth. By conceptualising sustain-ability as an immanent and emergent ability of ecological and social life, continuously...... to renew itself without eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming...

  2. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

    Energy Technology Data Exchange (ETDEWEB)

    Guo, Yuan-Yuan; Xue, Hai-Bin, E-mail: xuehaibin@tyut.edu.cn [Key Laboratory of Advanced Transducer and Intelligent Control system, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Physics and Optoelectronics, Taiyuan University of Technology, Taiyuan 030024 (China); Liu, Zhe-Jie, E-mail: pandanlzj@hotmail.com [Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576 (Singapore)

    2015-05-15

    We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs) consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.

  3. Oscillation characteristics of zero-field spin transfer oscillators with field-like torque

    Directory of Open Access Journals (Sweden)

    Yuan-Yuan Guo

    2015-05-01

    Full Text Available We theoretically investigate the influence of the field-like spin torque term on the oscillation characteristics of spin transfer oscillators, which are based on MgO magnetic tunnel junctions (MTJs consisting of a perpendicular magnetized free layer and an in-plane magnetized pinned layer. It is demonstrated that the field-like torque has a strong impact on the steady-state precession current region and the oscillation frequency. In particular, the steady-state precession can occur at zero applied magnetic field when the ratio between the field-like torque and the spin transfer torque takes up a negative value. In addition, the dependence of the oscillation properties on the junction sizes has also been analyzed. The results indicate that this compact structure of spin transfer oscillator without the applied magnetic field is practicable under certain conditions, and it may be a promising configuration for the new generation of on-chip oscillators.

  4. Searching for Global oscillations of Jupiter

    Science.gov (United States)

    Murphy, N.; Smith, E. J.; Rogers, W.; Gillam, S.; Rosner, R.; Baliunas, S.

    2000-12-01

    The detection of global oscillations of Jupiter would lead to significant advances in our understanding of giant planet internal structure, analogous to the enormous increase in knowledge of the sun's interior facilitated by helioseismology. In particular, the frequencies of p-mode oscillations will be strongly affected by the presence of density discontinuities and the planet's core size and structure. While it is clear from previous observations that such oscillations probably only exist with very small amplitudes, current instrumentation may still be able to detect them. We will describe a proposed experiment to detect (or place a firm upper amplitude limit on) global p-mode oscillations of Jupiter, using a magneto-optical filter on the Mt Wilson 100" telescope. We will describe the operation of the instrument, present preliminary data and describe models of instrument response which show that with 7 nights of data we can expect to detect signals with amplitudes less than 20 cm/s.

  5. Dynamical evolution of quantum oscillators toward equilibrium.

    Science.gov (United States)

    Usha Devi, A R; Rajagopal, A K

    2009-07-01

    A pure quantum state of large number N of oscillators, interacting via harmonic coupling, evolves such that any small subsystem noscillator is found to relax in a mixed density matrix of the Boltzmann canonical form. In two oscillator stationary subsystems, intraentanglement within the "system" oscillators is found to exist when the magnitude of the squeezing parameter of the bath is comparable in magnitude with that of the coupling strength.

  6. Generalized decomposition methods for singular oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, J.I. [Room I-320-D, E. T. S. Ingenieros Industriales, Universidad de Malaga, Plaza El Ejido, s/n 29013 Malaga (Spain)], E-mail: jirs@lcc.uma.es

    2009-10-30

    Generalized decomposition methods based on a Volterra integral equation, the introduction of an ordering parameter and a power series expansion of the solution in terms of the ordering parameter are developed and used to determine the solution and the frequency of oscillation of a singular, nonlinear oscillator with an odd nonlinearity. It is shown that these techniques provide solutions which are free from secularities if the unknown frequency of oscillation is also expanded in power series of the ordering parameter, require that the nonlinearities be analytic functions of their arguments, and, at leading-order, provide the same frequency of oscillation as two-level iterative techniques, the homotopy perturbation method if the constants that appear in the governing equation are expanded in power series of the ordering parameter, and modified artificial parameter - Linstedt-Poincare procedures.

  7. Monolithic, Widely Tunable, THz Local Oscillator Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This proposal describes development of a new type of quantum-cascade laser for use as a local oscillator at frequencies above 2 THz. The THz source described is a...

  8. Another look at synchronized neutrino oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Akhmedov, Evgeny, E-mail: akhmedov@mpi-hd.mpg.de [Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Mirizzi, Alessandro, E-mail: alessandro.mirizzi@ba.infn.it [Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Via Amendola 173, 70126 Bari (Italy); Istituto Nazionale di Fisica Nucleare - Sezione di Bari, Via Amendola 173, 70126 Bari (Italy)

    2016-07-15

    In dense neutrino backgrounds present in supernovae and in the early Universe neutrino oscillations may exhibit complex collective phenomena, such as synchronized oscillations, bipolar oscillations and spectral splits and swaps. We consider in detail possible decoherence effects on the simplest of these phenomena – synchronized neutrino oscillations that can occur in a uniform and isotropic neutrino gas. We develop an exact formalism of spectral moments of the flavour spin vectors describing such a system and then apply it to find analytical approaches that allow one to study decoherence effects on its late-time evolution. This turns out to be possible in part due to the existence of the (previously unknown) exact conservation law satisfied by the quantities describing the considered neutrino system. Interpretation of the decoherence effects in terms of neutrino wave packet separation is also given, both in the adiabatic and non-adiabatic regimes of neutrino flavour evolution.

  9. On the κ-Dirac oscillator revisited

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, F.M., E-mail: fmandrade@uepg.br [Departamento de Matemática e Estatística, Universidade Estadual de Ponta Grossa, 84030-900 Ponta Grossa, PR (Brazil); Silva, E.O., E-mail: edilbertoos@pq.cnpq.br [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil); Ferreira, M.M., E-mail: manojr.ufma@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil); Rodrigues, E.C., E-mail: ednilson.fisica@gmail.com [Departamento de Física, Universidade Federal do Maranhão, Campus Universitário do Bacanga, 65085-580 São Luís, MA (Brazil)

    2014-04-04

    This Letter is based on the κ-Dirac equation, derived from the κ-Poincaré–Hopf algebra. It is shown that the κ-Dirac equation preserves parity while breaks charge conjugation and time reversal symmetries. Introducing the Dirac oscillator prescription, p→p−imωβr, in the κ-Dirac equation, one obtains the κ-Dirac oscillator. Using a decomposition in terms of spin angular functions, one achieves the deformed radial equations, with the associated deformed energy eigenvalues and eigenfunctions. The deformation parameter breaks the infinite degeneracy of the Dirac oscillator. In the case where ε=0, one recovers the energy eigenvalues and eigenfunctions of the Dirac oscillator.

  10. Large quantum dots with small oscillator strength

    DEFF Research Database (Denmark)

    Stobbe, Søren; Schlereth, T.W.; Höfling, S.

    2010-01-01

    We have measured the oscillator strength and quantum efficiency of excitons confined in large InGaAs quantum dots by recording the spontaneous emission decay rate while systematically varying the distance between the quantum dots and a semiconductor-air interface. The size of the quantum dots...... is measured by in-plane transmission electron microscopy and we find average in-plane diameters of 40 nm. We have calculated the oscillator strength of excitons of that size assuming a quantum-dot confinement given by a parabolic in-plane potential and a hard-wall vertical potential and predict a very large...... oscillator strength due to Coulomb effects. This is in stark contrast to the measured oscillator strength, which turns out to be so small that it can be described by excitons in the strong confinement regime. We attribute these findings to exciton localization in local potential minima arising from alloy...

  11. Adaptive elimination of synchronization in coupled oscillator

    Science.gov (United States)

    Zhou, Shijie; Ji, Peng; Zhou, Qing; Feng, Jianfeng; Kurths, Jürgen; Lin, Wei

    2017-08-01

    We present here an adaptive control scheme with a feedback delay to achieve elimination of synchronization in a large population of coupled and synchronized oscillators. We validate the feasibility of this scheme not only in the coupled Kuramoto’s oscillators with a unimodal or bimodal distribution of natural frequency, but also in two representative models of neuronal networks, namely, the FitzHugh-Nagumo spiking oscillators and the Hindmarsh-Rose bursting oscillators. More significantly, we analytically illustrate the feasibility of the proposed scheme with a feedback delay and reveal how the exact topological form of the bimodal natural frequency distribution influences the scheme performance. We anticipate that our developed scheme will deepen the understanding and refinement of those controllers, e.g. techniques of deep brain stimulation, which have been implemented in remedying some synchronization-induced mental disorders including Parkinson disease and epilepsy.

  12. On the Design of Chaotic Oscillators

    DEFF Research Database (Denmark)

    Lindberg, Erik; Tamasevicius, A; Cenys, A.

    1998-01-01

    A discussion of the chaotic oscillator concept from a design methodology pointof view. The attributes of some chaoticoscillators are discussed and a systematicdesign method based on eigenvalue investigation is proposed. The method isillustrated with a chaotic Wien-bridgeoscillator design....

  13. Oscillation theory for second order dynamic equations

    CERN Document Server

    Agarwal, Ravi P; O''Regan, Donal

    2003-01-01

    The qualitative theory of dynamic equations is a rapidly developing area of research. In the last 50 years, the Oscillation Theory of ordinary, functional, neutral, partial and impulsive differential equations, and their discrete versions, has inspired many scholars. Hundreds of research papers have been published in every major mathematical journal. Many books deal exclusively with the oscillation of solutions of differential equations, but most of these books appeal only to researchers who already know the subject. In an effort to bring Oscillation Theory to a new and broader audience, the authors present a compact, but thorough, understanding of Oscillation Theory for second order differential equations. They include several examples throughout the text not only to illustrate the theory, but also to provide new direction.

  14. Climate Prediction Center Southern Oscillation Index

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is one of the CPC?s Monthly Atmospheric and Sea Surface Temperature (SST)Indices. It contains Southern Oscillation Index which is standardized sea level...

  15. Sustaining Rural Communities through Sustainable Agriculture.

    Science.gov (United States)

    Ikerd, John

    A 5-year collaborative project between Missouri, Michigan State, and Nebraska Universities to provide new opportunities for rural community self-development through sustainable agriculture had mixed results. This happened because community members did not understand the principles of sustainability, and because the extension education system was…

  16. Solar oscillations instrumentation and measurement theory

    Science.gov (United States)

    Appourchaux, T.

    1988-01-01

    Solar-oscillation instruments are reviewed. Common characteristics include detecting solar radial velocities on Fraunhofer lines with a 2-point measuring technique, high spectral resolution and stability, etc. The choice of the spectral line for getting a high signal to solar noise ratio is addressed. Velocity imaging of solar oscillations modes is detailed, including spatial sampling and span, highest observable degree. Applications of these different analyses is applied to existing or future helioseismology instruments.

  17. 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...... analysis leads to an equivalent ideal plastic yield limit that gives good coincidence between the simulated distributions and the experimentally determined distributions....

  18. Oscillator Phase Noise: A Geometrical Approach

    DEFF Research Database (Denmark)

    Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens

    2009-01-01

    We construct a coordinate-independent description of oscillator linear response through a decomposition scheme derived independently of any Floquet theoretic results. Trading matrix algebra for a simpler graphical methodology, the text will present the reader with an opportunity to gain an intuit...... an intuitive understanding of the well-known phase noise macromodel. The topics discussed in this paper include the following: orthogonal decompositions, AM–PM conversion, and nonhyperbolic oscillator noise response....

  19. Harmonic Oscillator SUSY Partners and Evolution Loops

    Directory of Open Access Journals (Sweden)

    David J. Fernández

    2012-07-01

    Full Text Available Supersymmetric quantum mechanics is a powerful tool for generating exactly solvable potentials departing from a given initial one. If applied to the harmonic oscillator, a family of Hamiltonians ruled by polynomial Heisenberg algebras is obtained. In this paper it will be shown that the SUSY partner Hamiltonians of the harmonic oscillator can produce evolution loops. The corresponding geometric phases will be as well studied.

  20. Taking a peek at Bloch oscillations

    Science.gov (United States)

    Morsch, Oliver

    2016-11-01

    Bloch oscillations arise when matter waves inside a periodic potential, such as a crystal lattice, are accelerated by a constant force. Keßler et al (2016 New J. Phys. 18 102001) have now experimentally tested a method that allows one to observe those oscillations continuously, without a destructive measurement on the matter wave. Their approach could help to make cold atom-based accelerometers and gravimeters more precise.

  1. Broadband hyperchaotic oscillator with delay line

    DEFF Research Database (Denmark)

    Cenys, Antanas; Lindberg, Erik; Anagnostopoulos, A. N.

    2002-01-01

    Dynamical systems with time delay can be employed as high dimensional hyperchaotic oscillators with multiple positive Lyapunov exponents. We describe an electronic circuit composed of a 3-stage amplifier and a delay line in the feedback loop. The 1st stage of the amplifier is a nonlinear one whil...... 20 dB. Mathematical models are presented. The oscillators are described either by a scalar nonlinear DDE or by a set combined of one nonlinear DDE and two linear ODEs....

  2. Dynamics-Enabled Nanoelectromechanical Systems (NEMS) Oscillators

    Science.gov (United States)

    2014-06-01

    AFRL-RY-WP-TR-2014-0144 DYNAMICS-ENABLED NANOELECTROMECHANICAL SYSTEMS ( NEMS ) OSCILLATORS Michael Roukes California Institute...SYSTEMS ( NEMS ) OSCILLATORS 5a. CONTRACT NUMBER FA8650-10-1-7029 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 61101E 6. AUTHOR(S) Michael Roukes...engineer, and demonstrate nonlinear-dynamics-enabled nanoelectromechanical system ( NEMS ) frequency-source technology. 15. SUBJECT TERMS

  3. 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 DuffingHolmes type oscillator the autonomous circuit has an internal positive feedback loop instead of an external periodic drive source. In addition......, it is supplemented with an RC inertial damping loop providing negative feedback. The circuit has been investigated both numerically and experimentally....

  4. Oscillating electrical motors, application and theory

    Energy Technology Data Exchange (ETDEWEB)

    Kudarauskas, S. [Klaipeda University, Department of Electrical Engineering, Klaipeda (Lithuania)

    2000-08-01

    The article analyses classification of electrical machines by the temporal and spatial properties of mechanical movement. It is purposive to group the machines by movement temporal properties thus marking out an independent class of oscillating machines. The article demonstrates operation principles, design diversity and practical utilisation of these machines. Principles of theoretical analysis of main regime (i.e. steady oscillations) are presented. The appendix presents rationale of analogy between electrical circuit and magnetic circuit from energy standpoint. (orig.)

  5. Pseudoclassical description of the Dirac Oscillator

    Science.gov (United States)

    Delsolmesa, Antonio; Martinezyromero, R. P.

    1995-01-01

    In this paper we discuss the Dirac Oscillator wave equation in terms of pseudoclassical language, using Grassmann variables to describe the internal degrees of freedom of the oscillator. Regarding the original wave equation as a classical constraint, we use the theory of constrained systems, to develop a reparameterization invariant lagrangian, which is the pseudoclassical equivalent of the quantum case. The consistency of the Hamiltonian formalism and the quantization procedure are also analyzed.

  6. pH-regulated chemical oscillators.

    Science.gov (United States)

    Orbán, Miklós; Kurin-Csörgei, Krisztina; Epstein, Irving R

    2015-03-17

    The hydrogen ion is arguably the most ubiquitous and important species in chemistry. It also plays a key role in nearly every biological process. In this Account, we discuss systems whose behavior is governed by oscillations in the concentration of hydrogen ion. The first chemical oscillators driven by changes in pH were developed a quarter century ago. Since then, about two dozen new pH oscillators, systems in which the periodic variation in pH is not just an indicator but an essential prerequisite of the oscillatory behavior, have been discovered. Mechanistic understanding of their behavior has grown, and new ideas for their practical application have been proposed and, in some cases, tested. Here we present a catalog of the known pH oscillators, divide them into mechanistically based categories based on whether they involve a single oxidant and reductant or an oxidant and a pair of reductants, and describe general mechanisms for these two major classes of systems. We also describe in detail the chemistry of one example from each class, hydrogen peroxide-sulfide and ferricyanide-iodate-sulfite. Finally, we consider actual and potential applications. These include using pH oscillators to induce oscillation in species that would otherwise be nonoscillatory, creating novel spatial patterns, generating periodic transitions between vesicle and micelle states, stimulating switching between folded and random coil states of DNA, building molecular motors, and designing pulsating drug delivery systems. We point out the importance for future applications of finding a batch pH oscillator, one that oscillates in a closed system for an extended period of time, and comment on the progress that has been made toward that goal.

  7. 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...... analysis leads to an equivalent ideal plastic yield limit that gives good coincidence between the simulated distributions and the experimentally determined distributions. (C) 1998 Published by Elsevier Science Ltd. All rights reserved....

  8. Mechanical oscillations in lasing microspheres

    Science.gov (United States)

    Toncelli, A.; Capuj, N. E.; Garrido, B.; Sledzinska, M.; Sotomayor-Torres, C. M.; Tredicucci, A.; Navarro-Urrios, D.

    2017-08-01

    We investigate the feasibility of activating coherent mechanical oscillations in lasing microspheres by modulating the laser emission at a mechanical eigenfrequency. To this aim, 1.5%Nd3+:Barium-Titanium-Silicate microspheres with diameters around 50 μm were used as high quality factor (Q > 106) whispering gallery mode lasing cavities. We have implemented a pump-and-probe technique in which the pump laser used to excite the Nd3+ ions is focused on a single microsphere with a microscope objective and a probe laser excites a specific optical mode with the evanescent field of a tapered fibre. The studied microspheres show monomode and multi-mode lasing action, which can be modulated in the best case up to 10 MHz. We have optically transduced thermally activated mechanical eigenmodes appearing in the 50-70 MHz range, the frequency of which decreases with increasing the size of the microspheres. In a pump-and-probe configuration, we observed modulation of the probe signal up to the maximum pump modulation frequency of our experimental setup, i.e., 20 MHz. This modulation decreases with frequency and is unrelated to lasing emission, pump scattering, or thermal effects. We associate this effect to free-carrier-dispersion induced by multiphoton pump light absorption. On the other hand, we conclude that, in our current experimental conditions, it was not possible to resonantly excite the mechanical modes. Finally, we discuss on how to overcome these limitations by increasing the modulation frequency of the lasing emission and decreasing the frequency of the mechanical eigenmodes displaying a strong degree of optomechanical coupling.

  9. A compact low-power oscillation circuit for the high performance silicon oscillating accelerometer

    Science.gov (United States)

    Zhang, Jiashi; Qiu, Anping; Shi, Qin; Xia, Guoming; Zhao, Yang

    2017-10-01

    This paper describes a compact and low-power oscillating circuit for silicon oscillating accelerometer (SOA). The influence of oscillation amplitude control strategy on accelerometer performance is analyzed. A rail to rail comparator replaces the traditional AGC (automatic gain control) circuit for oscillation amplitude control. It makes the circuit more compact, lower power consumption, and reduces the flicker noise introduced by amplitude control greatly. The experiment shows the bias stability is 13.3µg from 22.9µg, the bias-instability is 4.3µg from 9.3µg, and the system power consumption is reduced to 200mW from 1.2W.

  10. MEDIA PEMBELAJARAN ANALOG OSCILLATOR VIRTUAL LABOLATORY

    Directory of Open Access Journals (Sweden)

    Aji Widhi Wibowo

    2016-01-01

    Full Text Available The purpose of this research is to design and implement a Virtual Labolatory Materials Signal Processing Sub discussion 'Oscillator' Analog as Newspapers. Developers using the model Sutopo Ariesto Hadi (2003 as a method to produce the product. Consists of six stages: concept, design, material collecting, assembly, testing and distribution. This results in the development of Virtual media Labolatory with material 'Oscillator' with the results of 4 (four practicum digital oscillator, namely (1 Oscillator Wien Bridge, (2 Colpitts oscillator, (3 Oscillator Hartley and (4 astable multivibrator. Another result is that a user be jobsheet practicum. There are two types, namely: (1 jobsheet grip lecturers and (2 jobsheet for students. In Jobsheet there is a short book that contains the Manual on procedures for the use of virtual labolatory when practical and anatomical description of the product. Virtual Labolatory consists of the initial page (flash scren, the main page (home, pages and pages about the developer's lab referring to the story board. There are four (4 test are: (1 the truth polarity capacitor, (2 the connection (wiring, (3 mode frequency and time in the meter frequency

  11. Mathematical Modeling of an Oscillating Droplet

    Science.gov (United States)

    Berry, S.; Hyers, R. W.; Racz, L. M.; Abedian, B.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    Oscillating droplets are of interest in a number of disciplines. A practical application is the oscillating drop method, which is a technique for measuring surface tension and viscosity of liquid metals. It is especially suited to undercooled and highly reactive metals, because it is performed by electromagnetic levitation. The natural oscillation frequency of the droplets is related to the surface tension of the material, and the decay of oscillations is related to its viscosity. The fluid flow inside the droplet must be laminar in order for this technique to yield good results. Because no experimental method has yet been developed to visualize flow in electromagnetically-levitated oscillating metal droplets, mathematical modeling is required to determine whether or not turbulence occurs. Three mathematical models of the flow: (1) assuming laminar conditions, (2) using the k-epsilon turbulence model, and (3) using the RNG turbulence model, respectively, are compared and contrasted to determine the physical characteristics of the flow. It is concluded that the RNG model is the best suited for describing this problem. The goal of the presented work was to characterize internal flow in an oscillating droplet of liquid metal, and to verify the accuracy of the characterization by comparing calculated surface tension and viscosity.

  12. Sustainable Marketing : The Importance of Being a Sustainable Business

    OpenAIRE

    Reutlinger, Janina

    2012-01-01

    This thesis deals with sustainable marketing, as well as the necessity for more sustainability. The purpose of this thesis was to determine the importance of sustainable marketing for companies. The theoretical part is divided into sustainability and sustainable marketing. Sustainability covers current issues and sustainable development, which form a background for a better understanding of sustainable marketing. Sustainable marketing includes a definition of the concept, as well as susta...

  13. Impact of osmotic stress and ethanol inhibition in yeast cells on process oscillation associated with continuous very-high-gravity ethanol fermentation.

    Science.gov (United States)

    Wang, Liang; Zhao, Xin-Qing; Xue, Chuang; Bai, Feng-Wu

    2013-09-16

    VHG fermentation is a promising process engineering strategy aiming at improving ethanol titer, and thus saving energy consumption for ethanol distillation and distillage treatment. However, sustained process oscillation was observed during continuous VHG ethanol fermentation, which significantly affected ethanol fermentation performance of the system. Sustained process oscillation was investigated in continuous VHG ethanol fermentation, and stresses exerted on yeast cells by osmotic pressure from unfermented sugars and ethanol inhibition developed within the fermentation system were postulated to be major factors triggering this phenomenon. In this article, steady state was established for continuous ethanol fermentation with LG medium containing 120 g/L glucose, and then 160 g/L non-fermentable xylose was supplemented into the LG medium to simulate the osmotic stress on yeast cells under the VHG fermentation condition, but the fermentation process was still at steady state, indicating that the impact of osmotic stress on yeast cells was not the main reason for the process oscillation. However, when 30 g/L ethanol was supplemented into the LG medium to simulate the ethanol inhibition in yeast cells under the VHG fermentation condition, process oscillation was triggered, which was augmented with extended oscillation period and exaggerated oscillation amplitude as ethanol supplementation was increased to 50 g/L, but the process oscillation was gradually attenuated when the ethanol supplementations were stopped, and the steady state was restored. Furthermore, gas stripping was incorporated into the continuous VHG fermentation system to in situ remove ethanol produced by Saccharomyces cerevisiae, and the process oscillation was also attenuated, but restored after the gas stripping was interrupted. Experimental results indicated that ethanol inhibition rather than osmotic stress on yeast cells is one of the main factors triggering the process oscillation under the

  14. Organized Oscillations of Initially-Turbulent Flow Past a Cavity

    Energy Technology Data Exchange (ETDEWEB)

    J.C. Lin; D. Rockwell

    2002-09-17

    Flow past an open cavity is known to give rise to self-sustained oscillations in a wide variety of configurations, including slotted-wall, wind and water tunnels, slotted flumes, bellows-type pipe geometries, high-head gates and gate slots, aircraft components and internal piping systems. These cavity-type oscillations are the origin of coherent and broadband sources of noise and, if the structure is sufficiently flexible, flow-induced vibration as well. Moreover, depending upon the state of the cavity oscillation, substantial alterations of the mean drag may be induced. In the following, the state of knowledge of flow past cavities, based primarily on laminar inflow conditions, is described within a framework based on the flow physics. Then, the major unresolved issues for this class of flows will be delineated. Self-excited cavity oscillations have generic features, which are assessed in detail in the reviews of Rockwell and Naudascher, Rockwell, Howe and Rockwell. These features, which are illustrated in the schematic of Figure 1, are: (i) interaction of a vorticity concentration(s) with the downstream corner, (ii) upstream influence from this corner interaction to the sensitive region of the shear layer formed from the upstream corner of the cavity; (iii) conversion of the upstream influence arriving at this location to a fluctuation in the separating shear layer; and (iv) amplification of this fluctuation in the shear layer as it develops in the streamwise direction. In view of the fact that inflow shear-layer in the present investigation is fully turbulent, item (iv) is of particular interest. It is generally recognized, at least for laminar conditions at separation from the leading-corner of the cavity, that the disturbance growth in the shear layer can be described using concepts of linearized, inviscid stability theory, as shown by Rockwell, Sarohia, and Knisely and Rockwell. As demonstrated by Knisely and Rockwell, on the basis of experiments interpreted

  15. Suppression of oscillations in mean-field diffusion

    Indian Academy of Sciences (India)

    2015-01-28

    Jan 28, 2015 ... We study the role of mean-field diffusive coupling on suppression of oscillations for systems of limit cycle oscillators. We show that this coupling scheme not only induces amplitude death (AD) but also oscillation death (OD) in coupled identical systems. The suppression of oscillations in the parameter space ...

  16. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    Analysing processes of social learning this work addresses how action research can further new research orientations towards sustainability. Empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating...... on urban sustainability the need to move towards sustainability at societal level is conceptualised as a democratic challenge questioning the way we live on planet earth. By understanding sustainability as an immanent and emergent ability of ecological and social life, continuously to renew itself without...... eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming to provide local citizens...

  17. Handbook of sustainable engineering

    CERN Document Server

    Lee, Kun-Mo

    2013-01-01

    "The efficient utilization of energy, sustainable use of natural resources, and large-scale adoption of sustainable technologies is the key to a sustainable future. The Handbook of Sustainable Engineering provides tools that will help us achieve these goals". Nobel Prize Winner Dr. R.K. Pauchauri, Chairman, UN Intergovernmental Panel on Climate Change As global society confronts the challenges of diminishing resources, ecological degradation, and climate change, engineers play a crucial role designing and building technologies and products that fulfil our needs for utility and sustainability. The Handbook of Sustainable Engineering equips readers with the context and the best practices derived from both academic research and practical examples of successful implementations of sustainable technical solutions. The handbook’s content revolves around the two themes, new ways of thinking and new business models, including sustainable production, products, service systems and consumption while addressing key asse...

  18. FORUM: Is Ecotourism Sustainable?

    Science.gov (United States)

    Wall

    1997-07-01

    / It is legitimate to ask whether and in what form tourism might contribute to sustainable development. This is not the same as sustainable tourism which, as a single-sector approach to development, may overlook important linkages with other sectors. If tourism is to contribute to sustainable development, then it must be economically viable, ecologically sensitive and culturally appropriate. Ecotourism is often advocated as being a sustainable form of tourism but imprecision in terminology clouds basic issues and there are strong economic, ecological, and cultural reasons for believing that, even in its purest forms, ecotourism is likely to present substantial challenges to destination areas, particularly if it competes for scarce resources and displaces existing uses and users. Sustainable tourism and ecotourism are not synonyms, many forms of ecotourism may not be sustainable, and if ecotourism is to contribute to sustainable development, then careful planning and management will be required.KEY WORDS: Ecotourism; Sustainable development; Development; Tourism

  19. Livestock biodiversity and sustainability

    NARCIS (Netherlands)

    Hoffmann, I.

    2011-01-01

    Sustainable development equally includes environmental protection including biodiversity, economic growth and social equity, both within and between generations. The paper first reviews different aspects related to the sustainable use of livestock biodiversity and property regimes that influence

  20. Sustainable Public Bids

    Directory of Open Access Journals (Sweden)

    Gil César Costa de Paula

    2016-06-01

    Full Text Available In this article we will discuss the issue of sustainability in public procurement, given that the government in Brazil is constituted as a great promoter of economic development and needs to adapt its acquisitions worldwide sustainability agenda.

  1. Memristor-based relaxation oscillators using digital gates

    KAUST Repository

    Khatib, Moustafa A.

    2012-11-01

    This paper presents two memristor-based relaxation oscillators. The proposed oscillators are designed without the need of any reactive elements, i.e., capacitor or inductor. As the \\'resistance storage\\' property of the memristor can be exploited to generate the oscillation. The proposed oscillators have the advantage that they can be fully integrated on-chip giving an area-efficient solution. Furthermore, these oscillators give higher frequency other than the existing reactance-less oscillator and provide a wider range of the resistance. The concept of operation and the mathematical analysis for the proposed oscillators are explained and verified with circuit simulations showing an excellent agreement. © 2012 IEEE.

  2. Four-Phase Oscillators Employing Two Active Elements

    Directory of Open Access Journals (Sweden)

    V. Biolkova

    2011-04-01

    Full Text Available Two novel four-phase voltage-output oscillators are proposed. These circuits can also be utilized as quadrature oscillators with floating outputs. Each oscillator employs two DO-CIBA (Differential Output- Current Inverter Buffered Amplifier, two grounded capacitors, and four or three resistors. Independent control of the oscillation frequency (OF and oscillation condition is practicable in both oscillators. Real measurements on the oscillator specimens confirm the ability of easy OF control and extra low THD, which is less than 0.07%.

  3. Neuroelectric Tuning of Cortical Oscillations by Apical Dendrites in Loop Circuits

    Directory of Open Access Journals (Sweden)

    David LaBerge

    2017-06-01

    Full Text Available Bundles of relatively long apical dendrites dominate the neurons that make up the thickness of the cerebral cortex. It is proposed that a major function of the apical dendrite is to produce sustained oscillations at a specific frequency that can serve as a common timing unit for the processing of information in circuits connected to that apical dendrite. Many layer 5 and 6 pyramidal neurons are connected to thalamic neurons in loop circuits. A model of the apical dendrites of these pyramidal neurons has been used to simulate the electric activity of the apical dendrite. The results of that simulation demonstrated that subthreshold electric pulses in these apical dendrites can be tuned to specific frequencies and also can be fine-tuned to narrow bandwidths of less than one Hertz (1 Hz. Synchronous pulse outputs from the circuit loops containing apical dendrites can tune subthreshold membrane oscillations of neurons they contact. When the pulse outputs are finely tuned, they function as a local “clock,” which enables the contacted neurons to synchronously communicate with each other. Thus, a shared tuning frequency can select neurons for membership in a circuit. Unlike layer 6 apical dendrites, layer 5 apical dendrites can produce burst firing in many of their neurons, which increases the amplitude of signals in the neurons they contact. This difference in amplitude of signals serves as basis of selecting a sub-circuit for specialized processing (e.g., sustained attention within the typically larger layer 6-based circuit. After examining the sustaining of oscillations in loop circuits and the processing of spikes in network circuits, we propose that cortical functioning can be globally viewed as two systems: a loop system and a network system. The loop system oscillations influence the network system’s timing and amplitude of pulse signals, both of which can select circuits that are momentarily dominant in cortical activity.

  4. Design of a MEMS-Based Oscillator Using 180nm CMOS Technology.

    Directory of Open Access Journals (Sweden)

    Sukanta Roy

    Full Text Available Micro-electro mechanical system (MEMS based oscillators are revolutionizing the timing industry as a cost effective solution, enhanced with more features, superior performance and better reliability. The design of a sustaining amplifier was triggered primarily to replenish MEMS resonator's high motion losses due to the possibility of their 'system-on-chip' integrated circuit solution. The design of a sustaining amplifier observing high gain and adequate phase shift for an electrostatic clamp-clamp (C-C beam MEMS resonator, involves the use of an 180nm CMOS process with an unloaded Q of 1000 in realizing a fixed frequency oscillator. A net 122dBΩ transimpedance gain with adequate phase shift has ensured 17.22MHz resonant frequency oscillation with a layout area consumption of 0.121 mm2 in the integrated chip solution, the sustaining amplifier draws 6.3mW with a respective phase noise of -84dBc/Hz at 1kHz offset is achieved within a noise floor of -103dBC/Hz. In this work, a comparison is drawn among similar design studies on the basis of a defined figure of merit (FOM. A low phase noise of 1kHz, high figure of merit and the smaller size of the chip has accredited to the design's applicability towards in the implementation of a clock generative integrated circuit. In addition to that, this complete silicon based MEMS oscillator in a monolithic solution has offered a cost effective solution for industrial or biomedical electronic applications.

  5. Indicators for environmental sustainability

    DEFF Research Database (Denmark)

    Dong, Yan; Hauschild, Michael Zwicky

    2017-01-01

    . In this study, we reviewed indicators applied in life cycle assessment (LCA), planetary boundary framework (PB), and Sustainable Development Goals (SDGs) developed under United Nation. The aim is to 1) identify their applications and relevant decision context; 2) Review their indicators and categorize them......Decision making on sustainable consumption and production requires scientifically based information on sustainability. Different environmental sustainability targets exist for specific decision problems. To observe how well these targets are met, relevant environmental indicators are needed...

  6. Sustainable Learning Organizations

    Science.gov (United States)

    Velazquez, Luis E.; Esquer, Javier; Munguia, Nora E.; Moure-Eraso, Rafael

    2011-01-01

    Purpose: The purpose of this paper is to debate how companies may better become a sustainable learning organization by offering the most used and insightful concepts of sustainability. Design/methodology/approach: Through literature review, learning organization and sustainability perspectives are explored and compared. Findings: Learning…

  7. Measuring Educational Sustainability

    Science.gov (United States)

    Selvanathan, Rani G.

    2013-01-01

    There are many definitions that are attributable to the meaning of sustainability. Sustainability can be viewed as long-lasting, effective result of a project, venture, action, or investment without consuming additional future resources. Because of the wide nature of its applicability, a universal measure of sustainability is hard to come by. This…

  8. ORNL Annual Sustainability Report

    Energy Technology Data Exchange (ETDEWEB)

    Lapsa, Melissa Voss [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Nichols, Teresa A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-02-01

    As described in this report, we have made substantial progress across the 25 roadmaps of the Sustainable Campus Initiative. The report also outlines our plans to continue integrating sustainable practices into the planning, execution, and evaluation of all ORNL activities. We appreciate your interest in our journey to sustainability, and we welcome your comments, questions, and suggestions.

  9. Toward sustainable logistics

    NARCIS (Netherlands)

    Soysal, Mehmet; Bloemhof-Ruwaard, Jacqueline M.

    2017-01-01

    The fast evolution of sustainability leads to the development of a new fast-growing concept called sustainable logistics management. This research addresses recent business trends and challenges in logistics and their implications for sustainable logistics management. Additionally, we discuss policy

  10. LCA and Sustainability

    DEFF Research Database (Denmark)

    Moltesen, Andreas; Bjørn, Anders

    2017-01-01

    LCA is often presented as a sustainability assessment tool. This chapter analyses the relationship between LCA and sustainability. This is done by first outlining the history of the sustainability concept, which gained momentum with the Brundtland Commission’s report ‘Our Common Future report ’ i...

  11. Lean maturity, lean sustainability

    DEFF Research Database (Denmark)

    Jørgensen, Frances; Matthiesen, Rikke; Nielsen, Jacob

    2007-01-01

    Although lean is rapidly growing in popularity, its implementation is far from problem free and companies may experience difficulties sustaining long term success. In this paper, it is suggested that sustainable lean requires attention to both performance improvement and capability development...... that support lean capability development and consequently, lean sustainability....

  12. Food sustainability: diverging interpretations

    NARCIS (Netherlands)

    Aiking, H.; de Boer, J.

    2004-01-01

    The concept of sustainability in general and food sustainability, in particular, entails many aspects and many interpretations. During a conference on food sustainability a broad, multidisciplinary picture was painted and many key issues were dealt with, from ecology, economy and society. In

  13. Transferring Education for Sustainability

    Science.gov (United States)

    Gafoor, Kunnathodi Abdul; Umer Farooque, T. K.

    2013-01-01

    Sustainability stands for sustaining the past, meeting needs of the present without compromising the ability to meet future needs. It should meet the individual and social needs, present and future needs local and global needs. A sustainable education that meets this requirements surely be a transferable education; an education that transfers from…

  14. Sustainability: An Overview.

    Science.gov (United States)

    Wormsley, W. E.

    1990-01-01

    This article introduces a group of six papers on sustainability of programs for visually handicapped persons in developing countries. Sustainability is discussed from an anthropological perspective, noting the importance of a social soundness analysis and a social impact assessment, enemies of sustainability, and the need for broad local input in…

  15. Sustainability in logistics practice

    NARCIS (Netherlands)

    Hans-Heinrich Glöckner; Reinder Pieters; Stef Weijers

    2009-01-01

    This conceptual paper wants to emphasis the use of the concept of sustainability within logistics and especially transportation. While working on a new tool to help companies develop sustainable European networks, we discovered that we want to use a specific concept of sustainability: People, planet

  16. Marine Ecosystem Response to the Atlantic Multidecadal Oscillation

    Science.gov (United States)

    Edwards, Martin; Beaugrand, Gregory; Helaouët, Pierre; Alheit, Jürgen; Coombs, Stephen

    2013-01-01

    Against the backdrop of warming of the Northern Hemisphere it has recently been acknowledged that North Atlantic temperature changes undergo considerable variability over multidecadal periods. The leading component of natural low-frequency temperature variability has been termed the Atlantic Multidecadal Oscillation (AMO). Presently, correlative studies on the biological impact of the AMO on marine ecosystems over the duration of a whole AMO cycle (∼60 years) is largely unknown due to the rarity of continuously sustained biological observations at the same time period. To test whether there is multidecadal cyclic behaviour in biological time-series in the North Atlantic we used one of the world's longest continuously sustained marine biological time-series in oceanic waters, long-term fisheries data and historical records over the last century and beyond. Our findings suggest that the AMO is far from a trivial presence against the backdrop of continued temperature warming in the North Atlantic and accounts for the second most important macro-trend in North Atlantic plankton records; responsible for habitat switching (abrupt ecosystem/regime shifts) over multidecadal scales and influences the fortunes of various fisheries over many centuries. PMID:23460832

  17. Marine ecosystem response to the Atlantic Multidecadal Oscillation.

    Directory of Open Access Journals (Sweden)

    Martin Edwards

    Full Text Available Against the backdrop of warming of the Northern Hemisphere it has recently been acknowledged that North Atlantic temperature changes undergo considerable variability over multidecadal periods. The leading component of natural low-frequency temperature variability has been termed the Atlantic Multidecadal Oscillation (AMO. Presently, correlative studies on the biological impact of the AMO on marine ecosystems over the duration of a whole AMO cycle (∼60 years is largely unknown due to the rarity of continuously sustained biological observations at the same time period. To test whether there is multidecadal cyclic behaviour in biological time-series in the North Atlantic we used one of the world's longest continuously sustained marine biological time-series in oceanic waters, long-term fisheries data and historical records over the last century and beyond. Our findings suggest that the AMO is far from a trivial presence against the backdrop of continued temperature warming in the North Atlantic and accounts for the second most important macro-trend in North Atlantic plankton records; responsible for habitat switching (abrupt ecosystem/regime shifts over multidecadal scales and influences the fortunes of various fisheries over many centuries.

  18. Oscillations-free PID control of anesthetic drug delivery in neuromuscular blockade.

    Science.gov (United States)

    Medvedev, Alexander; Zhusubaliyev, Zhanybai T; Rosén, Olov; Silva, Margarida M

    2016-07-25

    The PID-control of drug delivery or the neuromuscular blockade (NMB) in closed-loop anesthesia is considered. The NMB system dynamics portrayed by a Wiener model can exhibit sustained nonlinear oscillations under realistic PID gains and for physiologically feasible values of the model parameters. Such oscillations, also repeatedly observed in clinical trials, lead to under- and over-dosing of the administered drug and undermine patient safety. This paper proposes a tuning policy for the proportional PID gain that via bifurcation analysis ensures oscillations-free performance of the control loop. Online estimates of the Wiener model parameters are needed for the controller implementation and monitoring of the closed-loop proximity to oscillation. The nonlinear dynamics of the PID-controlled NMB system are studied by bifurcation analysis. A database of patient models estimated under PID-controlled neuromuscular blockade during general anesthesia is utilized, along with the corresponding clinical measurements. The performance of three recursive algorithms is compared in the application at hand: an extended Kalman filter, a conventional particle filter (PF), and a PF making use of an orthonormal basis to estimate the probability density function from the particle set. It is shown that with a time-varying proportional PID gain, the type of equilibria of the closed-loop system remains the same as in the case of constant controller gains. The recovery time and frequency of oscillations are also evaluated in simulation over the database of patient models. Nonlinear identification techniques based on model linearization yield biased parameter estimates and thus introduce superfluous uncertainty. The bias and variance of the estimated models are related to the computational complexity of the identification algorithms, highlighting the superiority of the PFs in this safety-critical application. The study demonstrates feasibility of the proposed oscillation-free control

  19. An Optimal Free Energy Dissipation Strategy of the MinCDE Oscillator in Regulating Symmetric Bacterial Cell Division

    Science.gov (United States)

    Xiong, Liping; Lan, Ganhui

    2015-01-01

    Sustained molecular oscillations are ubiquitous in biology. The obtained oscillatory patterns provide vital functions as timekeepers, pacemakers and spacemarkers. Models based on control theory have been introduced to explain how specific oscillatory behaviors stem from protein interaction feedbacks, whereas the energy dissipation through the oscillating processes and its role in the regulatory function remain unexplored. Here we developed a general framework to assess an oscillator’s regulation performance at different dissipation levels. Using the Escherichia coli MinCDE oscillator as a model system, we showed that a sufficient amount of energy dissipation is needed to switch on the oscillation, which is tightly coupled to the system’s regulatory performance. Once the dissipation level is beyond this threshold, unlike stationary regulators’ monotonic performance-to-cost relation, excess dissipation at certain steps in the oscillating process damages the oscillator’s regulatory performance. We further discovered that the chemical free energy from ATP hydrolysis has to be strategically assigned to the MinE-aided MinD release and the MinD immobilization steps for optimal performance, and a higher energy budget improves the robustness of the oscillator. These results unfold a novel mode by which living systems trade energy for regulatory function. PMID:26317492

  20. LCA and Sustainability

    DEFF Research Database (Denmark)

    Moltesen, Andreas; Bjørn, Anders

    2017-01-01

    LCA is often presented as a sustainability assessment tool. This chapter analyses the relationship between LCA and sustainability. This is done by first outlining the history of the sustainability concept, which gained momentum with the Brundtland Commission’s report ‘Our Common Future report...... is then demonstrated, and the strategy of LCA to achieving environmental protection, namely to guide the reduction of environmental impacts per delivery of a function, is explained. The attempt to broaden the scope of LCA, beyond environmental protection, by so-called life cycle sustainability assessment (LCSA......) is outlined. Finally, the limitations of LCA in guiding a sustainable development are discussed....

  1. From sustainable buildings to sustainable business

    OpenAIRE

    Mia Andelin

    2012-01-01

    The United Nations Environment Program (UNEP) Sustainable Buildings & Climate Initiative reports that buildings are responsible for more than 40 percent of global energy use and over one third of global greenhouse gas (GHG) emissions. The construction and real estate sector has the potential to play a significant role in the response to climate change. During the latest years the increase in attention to sustainability and green building by planners, developers, and investors has been remarka...

  2. Parametric oscillators from factorizations employing a constant-shifted Riccati solution of the classical harmonic oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Rosu, H.C., E-mail: hcr@ipicyt.edu.mx [IPICyT, Instituto Potosino de Investigacion Cientifica y Tecnologica, Apdo Postal 3-74 Tangamanga, 78231 San Luis Potosi, S.L.P. (Mexico); Khmelnytskaya, K.V. [Universidad Autonoma de Queretaro, Centro Universitario, Cerro de las Campanas s/n, C.P. 76010 Santiago de Queretaro, Qro. (Mexico)

    2011-09-19

    We determine the kind of parametric oscillators that are generated in the usual factorization procedure of second-order linear differential equations when one introduces a constant shift of the Riccati solution of the classical harmonic oscillator. The mathematical results show that some of these oscillators could be of physical nature. We give the solutions of the obtained second-order differential equations and the values of the shift parameter providing strictly periodic and antiperiodic solutions. We also notice that this simple problem presents parity-time (PT) symmetry. Possible applications are mentioned. -- Highlights: → A particular Riccati solution of the classical harmonic oscillator is shifted by a constant. → Such a solution is used in the factorization brackets to get different equations of motion. → The properties of the parametric oscillators obtained in this way are examined.

  3. Nonlinear Analysis of Ring Oscillator and Cross-Coupled Oscillator Circuits

    KAUST Repository

    Ge, Xiaoqing

    2010-12-01

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

  4. Parameter oscillations in a very high gravity medium continuous ethanol fermentation and their attenuation on a multistage packed column bioreactor system.

    Science.gov (United States)

    Bai, F W; Chen, L J; Anderson, W A; Moo-Young, M

    2004-12-05

    The quasi-steady-states, marked by small fluctuations of residual glucose, ethanol, and biomass concentrations, and sustainable oscillations marked by big fluctuations of these monitored fermentation parameters were observed during the continuous ethanol fermentation of Saccharomyces cerevisiae when very high gravity media were fed and correspondingly high ethanol concentrations reached. A high ethanol concentration was shown to be one of the main factors that incited these oscillations, although the residual glucose level affected the patterns of these oscillations to some extent. The lag response of S. cerevisiae to high ethanol stress that causes the shifts of morphology, viability loss, and death of yeast cells is assumed to be one of the probable mechanisms behind these oscillations. It was predicted that the longer the delay of this response was, the longer the oscillation periods would be, which was validated by the experimental data and the comparison with the oscillatory behaviors reported for the ethanologen bacterium, Zymomonas mobilis. Furthermore, three tubular bioreactors in series were arranged to follow a stirred tank bioreactor to attenuate these oscillations. However, exaggerated oscillations were observed for the residual glucose, ethanol, and biomass concentrations measured in the broth from these tubular bioreactors. After the tubular reactors were packed with Intalox ceramic saddle packing, these oscillations were effectively attenuated and quasi-steady-states were observed during which there were very small fluctuations of residual glucose, ethanol, and biomass within the entire experimental run.

  5. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    to renew itself without eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming...... to provide local citizens with a greater say in the future of urban sustainability research, this book shows how action research can make important methodological contributions to processes of social learning between citizens and scientists by enabling free spaces in peoples everyday life and within academia......How can action research further new research orientations towards sustainability? This book, empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating on urban sustainability, answers this question...

  6. Action Research for Sustainability

    DEFF Research Database (Denmark)

    Egmose, Jonas

    to provide local citizens with a greater say in the future of urban sustainability research, this book shows how action research can make important methodological contributions to processes of social learning between citizens and scientists by enabling free spaces in peoples everyday life and within academia...... to renew itself without eroding its own foundation of existence, it argues that since sustainability cannot be invented but only supported (or eroded) by science, we need to reframe science in the role of sustaining sustain-ability. Through analyses of a three year action research programme, aiming......How can action research further new research orientations towards sustainability? This book, empirically situated in the field of upstream public engagement, involving local residents, researchers and practitioners in bottom-up processes deliberating on urban sustainability, answers this question...

  7. Sustainability in Business

    DEFF Research Database (Denmark)

    Tollin, Karin; Vej, Jesper

    2012-01-01

    How do companies integrate sustainability into their strategy and practices, and what factors explain their approach? In this paper a typology of sustainability strategies is presented as well as a conceptual framework relating sustainability at the company level to the functional level...... of marketing. The central contribution of the typology is a strategic and managerial view on sustainability. Furthermore, the typology shows that sustainability in business is enacted from different areas of competences and fields in the literature (e.g. supply chain management, corporate branding, value...... creation, product innovation and business model innovation). The empirical basis for the typology is an exploratory study of managers' mindsets about sustainability as strategy. Ten top managers involved with integrating sustainability within their companies have been interviewed. In order to reveal...

  8. Fur and Sustainability

    DEFF Research Database (Denmark)

    Skjold, Else; Csaba, Fabian

    2016-01-01

    This paper explores the notion of deeper luxury, which insists that 'real' luxury should involve sustainable practices in the production and consumption of luxury goods. It traces historical and recent developments in the field of fur, to understand the implications, uncertainties and ambiguities...... of luxury’s confrontation with sustainability. Considering fur in relation to future standards for luxury products, we raise questions about moral problematisation and justification of luxury in terms of sustainability. We first examine the encounter of luxury with sustainability and explain...... the significance of the notion of ‘deeper luxury’. After taking stock of the impact of sustainability on luxury and various directions in which sustainable luxury is evolving, we discuss concepts of sustainable development in relation to the history of moral problematisation of luxury. This leads to the case...

  9. Oscillations in atmospheric water above Switzerland

    Science.gov (United States)

    Hocke, Klemens; Navas-Guzmán, Francisco; Moreira, Lorena; Bernet, Leonie; Mätzler, Christian

    2017-10-01

    Cloud fraction (CF), integrated liquid water (ILW) and integrated water vapour (IWV) were continuously measured from 2004 to 2016 by the TROpospheric WAter RAdiometer (TROWARA) in Bern, Switzerland. There are indications for interannual variations of CF and ILW. A spectral analysis shows that IWV is dominated by an annual oscillation, leading to an IWV maximum of 24 kg m-2 in July to August and a minimum of 8 kg m-2 in February. The seasonal behaviour of CF and ILW is composed by both the annual and the semiannual oscillation. However, the annual oscillation of CF has a maximum in December while the annual oscillation of ILW has a maximum in July. The semiannual oscillations of CF and ILW are strong from 2010 to 2014. The normalized power spectra of ILW and CF show statistically significant spectral components with periods of 76, 85, 97 and 150 days. We find a similarity between the power spectra of ILW and CF with those of zonal wind at 830 hPa (1.5 km) above Bern. Particularly, the occurrence of higher harmonics in the CF and ILW spectra is possibly forced by the behaviour of the lower-tropospheric wind. The mean amplitude spectra of CF, ILW and IWV show increased short-term variability on timescales less than 40 days from spring to fall. We find a weekly cycle of CF and ILW from June to September with increased values on Saturday, Sunday and Monday.

  10. Antineutrino Oscillations in the Atmospheric Sector

    Energy Technology Data Exchange (ETDEWEB)

    Himmel, Alexander I. [California Inst. of Technology (CalTech), Pasadena, CA (United States)

    2011-05-01

    This thesis presents measurements of the oscillations of muon antineutrinos in the atmospheric sector, where world knowledge of antineutrino oscillations lags well behind the knowledge of neutrinos, as well as a search for vμ → $\\bar{v}$μ transitions. Differences between neutrino and antineutrino oscillations could be a sign of physics beyond the Standard Model, including non-standard matter interactions or the violation of CPT symmetry. These measurements leverage the sign-selecting capabilities of the magnetized steel-scintillator MINOS detectors to analyze antineutrinos from the NuMI beam, both when it is in neutrino-mode and when it is in antineutrino-mode. Antineutrino oscillations are observed at |Δ$\\bar{m}$atm 2| = (3.36-0.40+0.46(stat) ± 0.06(syst)) x 10-3 eV2 and sin2(2$\\bar{θ}$23) = 0.860-0.12+0.11(stat) ± 0.01(syst). The oscillation parameters measured for antineutrinos and those measured by MINOS for neutrinos differ by a large enough margin that the chance of obtaining two values as discrepant as those observed is only 2%, assuming the two measurements arise from the same underlying mechanism, with the same parameter values. No evidence is seen for neutrino-to-antineutrino transitions.

  11. Fractional Dynamics in Calcium Oscillation Model

    Directory of Open Access Journals (Sweden)

    Yoothana Suansook

    2015-01-01

    Full Text Available The calcium oscillations have many important roles to perform many specific functions ranging from fertilization to cell death. The oscillation mechanisms have been observed in many cell types including cardiac cells, oocytes, and hepatocytes. There are many mathematical models proposed to describe the oscillatory changes of cytosolic calcium concentration in cytosol. Many experiments were observed in various kinds of living cells. Most of the experimental data show simple periodic oscillations. In certain type of cell, there exists the complex periodic bursting behavior. In this paper, we have studied further the fractional chaotic behavior in calcium oscillations model based on experimental study of hepatocytes proposed by Kummer et al. Our aim is to explore fractional-order chaotic pattern in this oscillation model. Numerical calculation of bifurcation parameters is carried out using modified trapezoidal rule for fractional integral. Fractional-order phase space and time series at fractional order are present. Numerical results are characterizing the dynamical behavior at different fractional order. Chaotic behavior of the model can be analyzed from the bifurcation pattern.

  12. Viewing Majorana Bound States by Rabi Oscillations.

    Science.gov (United States)

    Wang, Zhi; Liang, Qi-Feng; Yao, Dao-Xin; Hu, Xiao

    2015-07-08

    We propose to use Rabi oscillation as a probe to view the fractional Josepshon relation (FJR) associated with Majorana bound states (MBSs) expected in one-dimensional topological superconductors. The system consists of a quantum dot (QD) and an rf-SQUID with MBSs at the Josephson junction. Rabi oscillations between energy levels formed by MBSs are induced by ac gate voltage controlling the coupling between QD and MBS when the photon energy proportional to the ac frequency matches gap between quantum levels formed by MBSs and QD. As a manifestation of the Rabi oscillation in the whole system involving MBSs, the electron occupation on QD oscillates with time, which can be measured by charge sensing techniques. With Floquet theorem and numerical analysis we reveal that from the resonant driving frequency for coherent Rabi oscillation one can directly map out the FJR cos(πΦ/Φ0) as a signature of MBSs, with Φ the magnetic flux through SQUID and Φ0 = hc/2e the flux quantum. The present scheme is expected to provide a clear evidence for MBSs under intensive searching.

  13. Pattern recognition with simple oscillating circuits

    Science.gov (United States)

    Hölzel, R. W.; Krischer, K.

    2011-07-01

    Neural network devices that inherently possess parallel computing capabilities are generally difficult to construct because of the large number of neuron-neuron connections. However, there exists a theoretical approach (Hoppensteadt and Izhikevich 1999 Phys. Rev. Lett. 82 2983) that forgoes the individual connections and uses only a global coupling: systems of weakly coupled oscillators with a time-dependent global coupling are capable of performing pattern recognition in an associative manner similar to Hopfield networks. The information is stored in the phase shifts of the individual oscillators. However, to date, even the feasibility of controlling phase shifts with this kind of coupling has not yet been established experimentally. We present an experimental realization of this neural network device. It consists of eight sinusoidal electrical van der Pol oscillators that are globally coupled through a variable resistor with the electric potential as the coupling variable. We estimate an effective value of the phase coupling strength in our experiment. For that, we derive a general approach that allows one to compare different experimental realizations with each other as well as with phase equation models. We demonstrate that individual phase shifts of oscillators can be experimentally controlled by a weak global coupling. Furthermore, supplied with a distorted input image, the oscillating network can indeed recognize the correct image out of a set of predefined patterns. It can therefore be used as the processing unit of an associative memory device.

  14. Microbiota Diurnal Rhythmicity Programs Host Transcriptome Oscillations.

    Science.gov (United States)

    Thaiss, Christoph A; Levy, Maayan; Korem, Tal; Dohnalová, Lenka; Shapiro, Hagit; Jaitin, Diego A; David, Eyal; Winter, Deborah R; Gury-BenAri, Meital; Tatirovsky, Evgeny; Tuganbaev, Timur; Federici, Sara; Zmora, Niv; Zeevi, David; Dori-Bachash, Mally; Pevsner-Fischer, Meirav; Kartvelishvily, Elena; Brandis, Alexander; Harmelin, Alon; Shibolet, Oren; Halpern, Zamir; Honda, Kenya; Amit, Ido; Segal, Eran; Elinav, Eran

    2016-12-01

    The intestinal microbiota undergoes diurnal compositional and functional oscillations that affect metabolic homeostasis, but the mechanisms by which the rhythmic microbiota influences host circadian activity remain elusive. Using integrated multi-omics and imaging approaches, we demonstrate that the gut microbiota features oscillating biogeographical localization and metabolome patterns that determine the rhythmic exposure of the intestinal epithelium to different bacterial species and their metabolites over the course of a day. This diurnal microbial behavior drives, in turn, the global programming of the host circadian transcriptional, epigenetic, and metabolite oscillations. Surprisingly, disruption of homeostatic microbiome rhythmicity not only abrogates normal chromatin and transcriptional oscillations of the host, but also incites genome-wide de novo oscillations in both intestine and liver, thereby impacting diurnal fluctuations of host physiology and disease susceptibility. As such, the rhythmic biogeography and metabolome of the intestinal microbiota regulates the temporal organization and functional outcome of host transcriptional and epigenetic programs. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. The vertical oscillations of coupled magnets

    Energy Technology Data Exchange (ETDEWEB)

    Li Kewei; Lin Jiahuang; Kang Zi Yang [Raffles Institution, 1 Raffles Institution Lane, Singapore 575954 (Singapore); Liang, Samuel Yee Wei [Anglo-Chinese School Independent, 121 Dover Road, Singapore 139650 (Singapore); Juan, Jeremias Wong Say, E-mail: likewei92@gmail.com [NUS High School of Mathematics and Science, 20 Clementi Avenue 1, Singapore 129957 (Singapore)

    2011-07-15

    The International Young Physicists' Tournament (IYPT) is a worldwide, annual competition for high school students. This paper is adapted from the winning solution to Problem 14, Magnetic Spring, as presented in the final round of the 23rd IYPT in Vienna, Austria. Two magnets were arranged on top of each other on a common axis. One was fixed, while the other could move vertically. Various parameters of interest were investigated, including the effective gravitational acceleration, the strength, size, mass and geometry of the magnets, and damping of the oscillations. Despite its simplicity, this setup yielded a number of interesting and unexpected relations. The first stage of the investigation was concerned only with the undamped oscillations of small amplitudes, and the period of small amplitude oscillations was found to be dependent only on the eighth root of important magnet properties such as its strength and mass. The second stage sought to investigate more general oscillations. A numerical model which took into account magnet size, magnet geometry and damping effects was developed to model the general oscillations. Air resistance and friction were found to be significant sources of damping, while eddy currents were negligible.

  16. Human gamma oscillations during slow wave sleep.

    Directory of Open Access Journals (Sweden)

    Mario Valderrama

    Full Text Available Neocortical local field potentials have shown that gamma oscillations occur spontaneously during slow-wave sleep (SWS. At the macroscopic EEG level in the human brain, no evidences were reported so far. In this study, by using simultaneous scalp and intracranial EEG recordings in 20 epileptic subjects, we examined gamma oscillations in cerebral cortex during SWS. We report that gamma oscillations in low (30-50 Hz and high (60-120 Hz frequency bands recurrently emerged in all investigated regions and their amplitudes coincided with specific phases of the cortical slow wave. In most of the cases, multiple oscillatory bursts in different frequency bands from 30 to 120 Hz were correlated with positive peaks of scalp slow waves ("IN-phase" pattern, confirming previous animal findings. In addition, we report another gamma pattern that appears preferentially during the negative phase of the slow wave ("ANTI-phase" pattern. This new pattern presented dominant peaks in the high gamma range and was preferentially expressed in the temporal cortex. Finally, we found that the spatial coherence between cortical sites exhibiting gamma activities was local and fell off quickly when computed between distant sites. Overall, these results provide the first human evidences that gamma oscillations can be observed in macroscopic EEG recordings during sleep. They support the concept that these high-frequency activities might be associated with phasic increases of neural activity during slow oscillations. Such patterned activity in the sleeping brain could play a role in off-line processing of cortical networks.

  17. Health and sustainability.

    Science.gov (United States)

    Kjӕrgård, Bente; Land, Birgit; Bransholm Pedersen, Kirsten

    2014-09-01

    In the present article, we explore how sustainable development strategies and health promotion strategies can be bridged. The concept of the 'duality of structure' is taken as our starting point for understanding the linkages between health promotion and sustainable development, and for uncovering the structural properties or conditions which either enable or constrain sustainable public health initiatives. We argue that strategies towards health promotion are not sufficiently integrated with strategies for sustainable development, and thus political strategies aimed at solving health problems or sustainability problems may cause new, undesired and unforeseen environmental or health problems. First, we explore how the relation between health and sustainability is articulated in international policy documents. Next, we develop a model for understanding the relation between health promotion and sustainability. Third, we use examples from agriculture and food production to illustrate that health and sustainability are mutually enabling and constraining. We conclude that while the renewed focus on food security and food inequalities has brought the health and sustainability dimensions of the food system onto the political agenda, the conceptualization of duality between health and sustainability could be a new platform for a critical and theoretical stance towards the market-oriented food system strategy. Thinking along the lines of duality means that the integration of health promotion strategies and sustainable development strategies cannot be based on an approach to integration in which either health or sustainability is given precedence over the other. From a duality perspective, integration means conceiving sustainability from a health perspective and health from a sustainability perspective. © The Author (2013). Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Backward bifurcation and oscillations in a nested immuno-eco-epidemiological model.

    Science.gov (United States)

    Barfield, Michael; Martcheva, Maia; Tuncer, Necibe; Holt, Robert D

    2018-12-01

    This paper introduces a novel partial differential equation immuno-eco-epidemiological model of competition in which one species is affected by a disease while another can compete with it directly and by lowering the first species' immune response to the infection, a mode of competition termed stress-induced competition. When the disease is chronic, and the within-host dynamics are rapid, we reduce the partial differential equation model (PDE) to a three-dimensional ordinary differential equation (ODE) model. The ODE model exhibits backward bifurcation and sustained oscillations caused by the stress-induced competition. Furthermore, the ODE model, although not a special case of the PDE model, is useful for detecting backward bifurcation and oscillations in the PDE model. Backward bifurcation related to stress-induced competition allows the second species to persist for values of its invasion number below one. Furthermore, stress-induced competition leads to destabilization of the coexistence equilibrium and sustained oscillations in the PDE model. We suggest that complex systems such as this one may be studied by appropriately designed simple ODE models.

  19. External drive to inhibitory cells induces alternating episodes of high- and low-amplitude oscillations.

    Directory of Open Access Journals (Sweden)

    Oscar J Avella Gonzalez

    Full Text Available Electrical oscillations in neuronal network activity are ubiquitous in the brain and have been associated with cognition and behavior. Intriguingly, the amplitude of ongoing oscillations, such as measured in EEG recordings, fluctuates irregularly, with episodes of high amplitude alternating with episodes of low amplitude. Despite the widespread occurrence of amplitude fluctuations in many frequency bands and brain regions, the mechanisms by which they are generated are poorly understood. Here, we show that irregular transitions between sub-second episodes of high- and low-amplitude oscillations in the alpha/beta frequency band occur in a generic neuronal network model consisting of interconnected inhibitory and excitatory cells that are externally driven by sustained cholinergic input and trains of action potentials that activate excitatory synapses. In the model, we identify the action potential drive onto inhibitory cells, which represents input from other brain areas and is shown to desynchronize network activity, to be crucial for the emergence of amplitude fluctuations. We show that the duration distributions of high-amplitude episodes in the model match those observed in rat prefrontal cortex for oscillations induced by the cholinergic agonist carbachol. Furthermore, the mean duration of high-amplitude episodes varies in a bell-shaped manner with carbachol concentration, just as in mouse hippocampus. Our results suggest that amplitude fluctuations are a general property of oscillatory neuronal networks that can arise through background input from areas external to the network.

  20. Robust ion current oscillations under a steady electric field: An ion channel analog

    Science.gov (United States)

    Yan, Yu; Wang, Yunshan; Senapati, Satyajyoti; Schiffbauer, Jarrod; Yossifon, Gilad; Chang, Hsueh-Chia

    2016-08-01

    We demonstrate a nonlinear, nonequilibrium field-driven ion flux phenomenon, which unlike Teorell's nonlinear multiple field theory, requires only the application of one field: robust autonomous current-mass flux oscillations across a porous monolith coupled to a capillary with a long air bubble, which mimics a hydrophobic protein in an ion channel. The oscillations are driven by the hysteretic wetting dynamics of the meniscus when electro-osmotic flow and pressure driven backflow, due to bubble expansion, compete to approach zero mass flux within the monolith. Delayed rupture of the film around the advancing bubble cuts off the electric field and switches the monolith mass flow from the former to the latter. The meniscus then recedes and repairs the rupture to sustain an oscillation for a range of applied fields. This generic mechanism shares many analogs with current oscillations in cell membrane ion channel. At sufficiently high voltage, the system undergoes a state transition characterized by appearance of the ubiquitous 1 /f power spectrum.

  1. Noisy transcription factor NF-κB oscillations stabilize and sensitize cytokine signaling in space

    Science.gov (United States)

    Gangstad, Sirin W.; Feldager, Cilie W.; Juul, Jeppe; Trusina, Ala

    2013-02-01

    NF-κB is a major transcription factor mediating inflammatory response. In response to a pro-inflammatory stimulus, it exhibits a characteristic response—a pulse followed by noisy oscillations in concentrations of considerably smaller amplitude. NF-κB is an important mediator of cellular communication, as it is both activated by and upregulates production of cytokines, signals used by white blood cells to find the source of inflammation. While the oscillatory dynamics of NF-κB has been extensively investigated both experimentally and theoretically, the role of the noise and the lower secondary amplitude has not been addressed. We use a cellular automaton model to address these issues in the context of spatially distributed communicating cells. We find that noisy secondary oscillations stabilize concentric wave patterns, thus improving signal quality. Furthermore, both lower secondary amplitude as well as noise in the oscillation period might be working against chronic inflammation, the state of self-sustained and stimulus-independent excitations. Our findings suggest that the characteristic irregular secondary oscillations of lower amplitude are not accidental. On the contrary, they might have evolved to increase robustness of the inflammatory response and the system's ability to return to a pre-stimulated state.

  2. Oscillation of large air bubble cloud

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Y.Y.; Kim, H.Y.; Park, J.K. [Korea Atomic Energy Research Inst., Daejeon (Korea, Republic of)

    2001-07-01

    The behavior of a large air bubble cloud, which is generated by the air discharged from a perforated sparger, is analyzed by solving Rayleigh-Plesset equation, energy equations and energy balance equation. The equations are solved by Runge-Kutta integration and MacCormack finite difference method. Initial conditions such as driving pressure, air volume, and void fraction strongly affect the bubble pressure amplitude and oscillation frequency. The pool temperature has a strong effect on the oscillation frequency and a negligible effect on the pressure amplitude. The polytropic constant during the compression and expansion processes of individual bubbles ranges from 1.0 to 1.4, which may be attributed to the fact that small bubbles oscillated in frequencies different from their resonance. The temperature of the bubble cloud rapidly approaches the ambient temperature, as is expected from the polytropic constants being between 1.0 and 1.4. (authors)

  3. Linear Isentropic Oscillations of Stars Theoretical Foundations

    CERN Document Server

    Smeyers, Paul

    2010-01-01

    The study of stellar oscillations is the preeminent way to investigate the stability of stars and to interpret their variability. The theory of the linear, isentropic oscillations of isolated gaseous stars, and thus of compressible spherically symmetric equilibrium configurations, has largely been developed from the viewpoint of the hypothesis of the physical radial pulsations of stars. Written for doctoral students and researchers, this monograph aims to provide a systematic and consistent survey of the fundamentals of the theory of free, linear, isentropic oscillations in spherically symmetric, gaseous equilibrium stars. The first part of the book presents basic concepts and equations, the distinction between spheroidal and toroidal normal modes, the solution of Poisson’s differential equation for the perturbation of the gravitational potential, and Hamilton’s variational principle. The second part is devoted to the possible existence of waves propagating in the radial direction, the origin and classifi...

  4. Simulations of Oscillating Hydrofoils in Array Configurations

    Science.gov (United States)

    Franck, Jennifer; Simeski, Filip; Spaulding, Arianne

    2016-11-01

    The vortex and wake interactions of multiple oscillating foils are investigated computationally for energy harvesting applications. Oscillating with high pitch and heave amplitudes to maximize power production, the elliptical-shaped foils generate large coherent vortices at the leading and trailing edge, which are shed downstream to create a large highly structured wake of vortices with alternating sign. Downstream foils oscillate within the large organized wake at a relative phase angle to the lead foil such that power efficiency is optimized. When placed directly downstream of one another, the optimal phase of a second foil is to avoid interactions with the first foil's wake, generating less than half of the total power of the first foil. However, when placed in a staggered configuration the downstream foil has an increase in efficiency through constructive vortex-foil interactions. Funded by ARPAe.

  5. Directional Transverse Oscillation Vector Flow Estimation

    DEFF Research Database (Denmark)

    Jensen, Jørgen Arendt

    2017-01-01

    A method for estimating vector velocities using transverse oscillation (TO) combined with directional beamforming is presented. In Directional Transverse Oscillation (DTO) a normal focused field is emitted and the received signals are beamformed in the lateral direction transverse to the ultrasound...... beam to increase the amount of data for vector velocity estimation. The approach is self-calibrating as the lateral oscillation period is estimated from the directional signal through a Fourier transform to yield quantitative velocity results over a large range of depths. The approach was extensively...... simulated using Field IIpro and implemented on the experimental SARUS scanner in connection with a BK Medical 8820e convex array transducer. Velocity estimates for DTO are found for beam-to-flow angles of 60, 75, and 90, and vessel depths from 24 to 156 mm. Using 16 emissions the Standard Deviation (SD...

  6. Synchronization of Time-Continuous Chaotic Oscillators

    DEFF Research Database (Denmark)

    Yanchuk, S.; Maistrenko, Yuri; Mosekilde, Erik

    2003-01-01

    Considering a system of two coupled identical chaotic oscillators, the paper first establishes the conditions of transverse stability for the fully synchronized chaotic state. Periodic orbit threshold theory is applied to determine the bifurcations through which low-periodic orbits embedded...... in the fully synchronized state lose their transverse stability, and the appearance of globally and locally riddled basins of attraction is discussed, respectively, in terms of the subcritical, supercritical nature of the riddling bifurcations. We show how the introduction of a small parameter mismatch between...... the interacting chaotic oscillators causes a shift of the synchronization manifold. The presence of a coupling asymmetry is found to lead to further modifications of the destabilization process. Finally, the paper considers the problem of partial synchronization in a system of four coupled Rossler oscillators...

  7. Quantum anharmonic oscillator: The airy function approach

    Energy Technology Data Exchange (ETDEWEB)

    Maiz, F., E-mail: fethimaiz@gmail.com [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia); University of Cartage, Nabeul Engineering Preparatory Institute, Merazka, 8000 Nabeul (Tunisia); AlFaify, S. [King Khalid University, Faculty of Science, Physics Department, PO Box 9004, Abha 61413, Asseer (Saudi Arabia)

    2014-05-15

    New and simple numerical method is being reported to solve anharmonic oscillator problems. The method is setup to approach the real potential V(x) of the anharmonic oscillator system as a piecewise linear potential u(x) and to solve the Schrödinger equation of the system using the Airy function. Then, solutions continuity conditions lead to the energy quantification condition, and consequently, the energy eigenvalues. For testing purpose, the method was applied on the sextic and octic oscillators systems. The proposed method is found to be realistic, computationally simple, and having high degrees of accuracy. In addition, it can be applied to any form of potential. The results obtained by the proposed method were seen closely agreeing with results reached by other complicated methods.

  8. Theoretical Interpretation of Current Neutrino Oscillation Data

    Science.gov (United States)

    Fogli, Gianluigi; Lisi, Eligio

    We discuss the theoretical interpretation of neutrino oscillation data in terms of 3v and 4v mixing. Two-neutrino oscillations, often used to describe experimental results in a first approximation, are briefly recalled (Sect. 5.1). The main focus of our review is 3v mixing (Sect. 5.2), which accommodates both the negative results of oscillation searches at reactors (Sect. 5.3) and the evidence for flavor transitions obtained from atmospheric and solar neutrino data (Sects. 5.4 and 5.5). The status and problems of 4v scenarios embedding the additional LSND signal are also discussed (Sect. 5.7). Finally, we outline the impact of the very latest data (Sect. 5.8). Standard electroweak neutrino interactions are assumed in all cases; scenarios with nonstandard dynamics are beyond the scope of this review.

  9. THERMAL OSCILLATIONS IN LIQUID HELIUM TARGETS.

    Energy Technology Data Exchange (ETDEWEB)

    WANG,L.; JIA,L.X.

    2001-07-16

    A liquid helium target for the high-energy physics was built and installed in the proton beam line at the Alternate Gradient Synchrotron of Brookhaven National Laboratory in 2001. The target flask has a liquid volume of 8.25 liters and is made of thin Mylar film. A G-M/J-T cryocooler of five-watts at 4.2K was used to produce liquid helium and refrigerate the target. A thermosyphon circuit for the target was connected to the J-T circuit by a liquid/gas separator. Because of the large heat load to the target and its long transfer lines, thermal oscillations were observed during the system tests. To eliminate the oscillation, a series of tests and analyses were carried out. This paper describes the phenomena and provides the understanding of the thermal oscillations in the target system.

  10. Circadian oscillators in the mouse brain

    DEFF Research Database (Denmark)

    Rath, Martin F; Rovsing, Louise; Møller, Morten

    2014-01-01

    The circadian timekeeper of the mammalian brain resides in the suprachiasmatic nucleus of the hypothalamus (SCN), and is characterized by rhythmic expression of a set of clock genes with specific 24-h daily profiles. An increasing amount of data suggests that additional circadian oscillators...... residing outside the SCN have the capacity to generate peripheral circadian rhythms. We have recently shown the presence of SCN-controlled oscillators in the neocortex and cerebellum of the rat. The function of these peripheral brain clocks is unknown, and elucidating this could involve mice...... and granular cell layers of the cerebellar cortex of the mouse brain. Among these, Per1, Per2, Cry1, Arntl, and Nr1d1 exhibit circadian rhythms suggesting that local running circadian oscillators reside within neurons of the mouse neocortex and cerebellar cortex. The temporal expression profiles of clock genes...

  11. The harmonic oscillator and nuclear physics

    Science.gov (United States)

    Rowe, D. J.

    1993-01-01

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

  12. Self oscillating PWM modulators, a topological comparison

    DEFF Research Database (Denmark)

    Poulsen, Søren; Andersen, Michael Andreas E.

    2004-01-01

    's work with switch mode audio power amplifiers, where linear tracking of the reference signal is of major importance. Use of the modulator topologies presented are not limited to this kind of equipment, but can be used in a very wide range of applications from very low to very high power levels....... or fs/ð range respectively, where fs is the switching frequency of the converter. For some applications this will require unacceptable high switching frequency to achieve enough control loop bandwidth for the desired dynamic performance. With self oscillating modulators, the open loop bandwidth is equal...... or by shaping the open loop function of the modulator so its gain and phase response causes a closed loop natural oscillation. The two main types of self oscillating modulators have many similarities, but differences in dynamic performance and linearity are present. The work presented is related to the author...

  13. New Realizations of Single OTRA-Based Sinusoidal Oscillators

    Directory of Open Access Journals (Sweden)

    Hung-Chun Chien

    2014-01-01

    Full Text Available This study proposes three new sinusoidal oscillators based on an operational transresistance amplifier (OTRA. Each of the proposed oscillator circuits consists of one OTRA combined with a few passive components. The first circuit is an OTRA-based minimum RC oscillator. The second circuit is capable of providing independent control on the condition of oscillation without affecting the oscillation frequency. The third circuit exhibits independent control of oscillation frequency through a capacitor. This study first introduces the OTRA and the related formulations of the proposed oscillator circuits, and then discusses the nonideal effects, sensitivity analyses, and frequency stability of the presented circuits. The proposed oscillators exhibit low sensitivities and good frequency stability. Because the presented circuits feature low impedance output, they can be connected directly to the next stage without cascading additional voltage buffers. HSPICE simulations and experimental results confirm the feasibility of the new oscillator circuits.

  14. The pervasiveness and plasticity of circadian oscillations: the coupled circadian-oscillators framework.

    Science.gov (United States)

    Patel, Vishal R; Ceglia, Nicholas; Zeller, Michael; Eckel-Mahan, Kristin; Sassone-Corsi, Paolo; Baldi, Pierre

    2015-10-01

    Circadian oscillations have been observed in animals, plants, fungi and cyanobacteria and play a fundamental role in coordinating the homeostasis and behavior of biological systems. Genetically encoded molecular clocks found in nearly every cell, based on negative transcription/translation feedback loops and involving only a dozen genes, play a central role in maintaining these oscillations. However, high-throughput gene expression experiments reveal that in a typical tissue, a much larger fraction ([Formula: see text]) of all transcripts oscillate with the day-night cycle and the oscillating species vary with tissue type suggesting that perhaps a much larger fraction of all transcripts, and perhaps also other molecular species, may bear the potential for circadian oscillations. To better quantify the pervasiveness and plasticity of circadian oscillations, we conduct the first large-scale analysis aggregating the results of 18 circadian transcriptomic studies and 10 circadian metabolomic studies conducted in mice using different tissues and under different conditions. We find that over half of protein coding genes in the cell can produce transcripts that are circadian in at least one set of conditions and similarly for measured metabolites. Genetic or environmental perturbations can disrupt existing oscillations by changing their amplitudes and phases, suppressing them or giving rise to novel circadian oscillations. The oscillating species and their oscillations provide a characteristic signature of the physiological state of the corresponding cell/tissue. Molecular networks comprise many oscillator loops that have been sculpted by evolution over two trillion day-night cycles to have intrinsic circadian frequency. These oscillating loops are coupled by shared nodes in a large network of coupled circadian oscillators where the clock genes form a major hub. Cells can program and re-program their circadian repertoire through epigenetic and other mechanisms. High

  15. [What is sustainability science?].

    Science.gov (United States)

    Wu, Jian-Guo; Guo, Xiao-Chuan; Yang, Jie; Qian, Gui-Xia; Niu, Jian-Ming; Liang, Cun-Zhu; Zhang, Qing; Li, Ang

    2014-01-01

    Sustainability is the theme of our time and also the grandest challenge to humanity. Since the 1970s, the term, sustainable development, has frequently appeared in the scientific literature, governmental documents, media promotions for public goods, and commercial advertisements. However, the science that provides the theoretical foundation and practical guidance for sustainable development--sustainability science--only began to emerge in the beginning of the 21st century. Nevertheless, the field has rapidly developed in depth and expanded in scope during the past decade, with its core concepts and research methods coalescing. China, as the most populous country in the world and home to the philosophical root of sustainability science-the unity of man and nature, is obligated to take upon the challenge of our time, to facilitate global sustainability while pursuing the Chinese Dream, and to play a leading role in the development of sustainability science. Toward this grandiose goal, this paper presents the first Chinese introduction to sustainability science, which discusses its basic concepts, research questions, and future directions. Sustainability science is the study of the dynamic relationship between humans and the environment, particularly focusing on the vulnerability, robustness, resilience, and stability of the coupled human-environment system. It is a transdisciplinary science that integrates natural sciences with humanities and social sciences. It hinges on the environment-economy-society nexus, and merges basic and applied research. The key components of sustainability often change with time, place, and culture, and thus sustainability science needs to emphasize multi-scale studies in space and time, with emphasis on landscapes and regions over a horizon of 50 to 100 years. It needs to focus on the relationship between ecosystem services and human well-being, as influenced by biodiversity and ecosystem processes as well as climate change, land use

  16. decolonising sustainability: subverting and appropriating

    African Journals Online (AJOL)

    magnitude for environmental education. We can speak of sustainable development, sustainable economies, sustainable democracy, a sustainable world order, and sustainable modes of health maintenance, but when we turn to spiritual matters we are faced with the black hole of green· politics: what constitutes sustainable.

  17. Electroacoustic oscillations in the LEP SC. cavities

    CERN Document Server

    Boussard, Daniel; Tückmantel, Joachim

    1996-01-01

    The LEP superconducting cavities have been plagued by electroacoustic oscillations. Tests have been done to eliminate these by a special feed-back loop in the tuning circuit as well as a feed-forward path, but they could only be eliminated safely up to the design field by running the cavities close to tune neglecting beam-loading compensation. This technique proved successful during the first LEP2 test run at 70 GeV. The mechanism and essential parameters driving these oscillations have been analysed as well as the corresponding stronger loading of the power coupler.

  18. Solar Dynamo Driven by Periodic Flow Oscillation

    Science.gov (United States)

    Mayr, Hans G.; Hartle, Richard E.; Einaudi, Franco (Technical Monitor)

    2001-01-01

    We have proposed that the periodicity of the solar magnetic cycle is determined by wave mean flow interactions analogous to those driving the Quasi Biennial Oscillation in the Earth's atmosphere. Upward propagating gravity waves would produce oscillating flows near the top of the radiation zone that in turn would drive a kinematic dynamo to generate the 22-year solar magnetic cycle. The dynamo we propose is built on a given time independent magnetic field B, which allows us to estimate the time dependent, oscillating components of the magnetic field, (Delta)B. The toroidal magnetic field (Delta)B(sub phi) is directly driven by zonal flow and is relatively large in the source region, (Delta)(sub phi)/B(sub Theta) much greater than 1. Consistent with observations, this field peaks at low latitudes and has opposite polarities in both hemispheres. The oscillating poloidal magnetic field component, (Delta)B(sub Theta), is driven by the meridional circulation, which is difficult to assess without a numerical model that properly accounts for the solar atmosphere dynamics. Scale-analysis suggests that (Delta)B(sub Theta) is small compared to B(sub Theta) in the dynamo region. Relative to B(sub Theta), however, the oscillating magnetic field perturbations are expected to be transported more rapidly upwards in the convection zone to the solar surface. As a result, (Delta)B(sub Theta) (and (Delta)B(sub phi)) should grow relative to B(sub Theta), so that the magnetic fields reverse at the surface as observed. Since the meridional and zonai flow oscillations are out of phase, the poloidal magnetic field peaks during times when the toroidal field reverses direction, which is observed. With the proposed wave driven flow oscillation, the magnitude of the oscillating poloidal magnetic field increases with the mean rotation rate of the fluid. This is consistent with the Bode-Blackett empirical scaling law, which reveals that in massive astrophysical bodies the magnetic moment tends

  19. Neutrino oscillations in the early Universe

    CERN Document Server

    Kirilova, Daniela P

    2001-01-01

    We discuss the oscillations effects on neutrinos in the early Universe and update the cosmological constraints on the oscillation parameters. It is shown that sterile LOW solution to the solar neutrino problem is almost completely excluded from cosmological nucleosynthesis considerations. Two possibilities for the relaxation of this constraint are discussed: high primordial helium-4 yield and a relic lepton asymmetry present at nucleosynthesis epoch. The numerical analysis proved that Y_p=0.25 only relaxes the constraint on LOW solution, while L > 10^{-5} is capable to remove it.

  20. Upward-going muons and neutrino oscillations

    Science.gov (United States)

    Fogli, G. L.; Lisi, E.; Marrone, A.

    1998-05-01

    The available upward-going muon data from the Kamiokande, Baksan, MACRO, IMB, and SuperKamiokande experiments are reviewed and combined. Bounds on the neutrino mass and mixing parameters are derived for oscillations in two and three flavors. These bounds are not in significant conflict with the oscillation solution to the atmospheric neutrino flavor anomaly observed in the sub-GeV and multi-GeV energy range. The combination of all the available atmospheric data tends to favor the νμνe channel with respect to the νμντ channel, and to disfavor the threefold maximal mixing scenario.

  1. 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...

  2. Phase locking between Josephson soliton oscillators

    DEFF Research Database (Denmark)

    Holst, T.; Hansen, Jørn Bindslev; Grønbech-Jensen, N.

    1990-01-01

    We report observations of phase-locking phenomena between two Josephson soliton (fluxon) oscillators biased in self-resonant modes. The locking strength was measured as a function of bias conditions. A frequency tunability of the phase-locked oscillators up to 7% at 10 GHz was observed. Two coupled...... perturbed sine-Gordon equations were derived from an equivalent circuit consisting of inductively coupled, nonlinear, lossy transmission lines. These equations were solved numerically to find the locking regions. Good qualitative agreement was found between the experimental results and the calculations...

  3. Hyperbolic geometry of Kuramoto oscillator networks

    Science.gov (United States)

    Chen, Bolun; Engelbrecht, Jan R.; Mirollo, Renato

    2017-09-01

    Kuramoto oscillator networks have the special property that their trajectories are constrained to lie on the (at most) 3D orbits of the Möbius group acting on the state space T N (the N-fold torus). This result has been used to explain the existence of the N-3 constants of motion discovered by Watanabe and Strogatz for Kuramoto oscillator networks. In this work we investigate geometric consequences of this Möbius group action. The dynamics of Kuramoto phase models can be further reduced to 2D reduced group orbits, which have a natural geometry equivalent to the unit disk \

  4. NOx Emission Reduction by Oscillating Combustion

    Energy Technology Data Exchange (ETDEWEB)

    John C. Wagner

    2004-03-31

    High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the

  5. NOx Emission Reduction by Oscillating combustion

    Energy Technology Data Exchange (ETDEWEB)

    Institute of Gas Technology

    2004-01-30

    High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the

  6. Neutrino Oscillations Present Status and Future Plans

    CERN Document Server

    Thomas, Jennifer

    2008-01-01

    This book reviews the status of a very exciting field - neutrino oscillations - at a very important time. The fact that neutrinos have mass has only been proved in the last few years and the acceptance of that fact has opened up a whole new area of study to understand the fundamental parameters of the mixing matrix. The book summarizes the results from all the experiments which have played a role in the measurement of neutrino oscillations and briefly describes the scope of some new planned experiments. Contributions include a theoretical introduction by Stephen Parke from FNAL, as well as art

  7. Interaction of low- and high-frequency oscillations in resonant systems with distributed interaction

    Science.gov (United States)

    Bulgakov, S. A.; Vavriv, D. M.

    1991-03-01

    The oscillation dynamics of synchronized resonant oscillators with distributed interaction in the presence of LF modulation of the beam is analyzed. It is shown that the interaction of LF and HF oscillations can lead to the excitation of stochastic oscillations. Conditions and scenarios of the generation of such oscillations are established for oscillators with soft and hard oscillation-excitation modes.

  8. Amplitude death and resurgence of oscillation in networks of mobile oscillators

    Science.gov (United States)

    Majhi, Soumen; Ghosh, Dibakar

    2017-05-01

    The phenomenon of amplitude death has been explored using a variety of different coupling strategies in the last two decades. In most of the works, the basic coupling arrangement is considered to be static over time, although many realistic systems exhibit significant changes in the interaction pattern as time varies. In this article, we study the emergence of amplitude death in a dynamical network composed of time-varying interaction amidst a collection of random walkers in a finite region of three-dimensional space. We consider an oscillator for each walker and demonstrate that depending upon the network parameters and hence the interaction between them, the global oscillation in the network gets suppressed. In this framework, the vision range of each oscillator decides the number of oscillators with which it interacts. In addition, with the use of an appropriate feedback parameter in the coupling strategy, we articulate how the suppressed oscillation can be resurrected in the systems' parameter space. The phenomenon of amplitude death and the resurgence of oscillation is investigated taking limit cycle and chaotic oscillators for broad ranges of the parameters, like the interaction strength k between the entities, the vision range r and the speed of movement v.

  9. Multifrequency Oscillator-Type Active Printed Antenna Using Chaotic Colpitts Oscillator

    Directory of Open Access Journals (Sweden)

    Bibha Kumari

    2014-01-01

    Full Text Available This paper presents a new concept to realize a multifrequency Oscillator-type active printed monopole antenna. The concept of period doubling route to chaos is exploited to generate the multiple frequencies. The chaotic Colpitts oscillator is integrated with the printed monopole antenna (PMA on the same side of the substrate to realize an Oscillator-type active antenna where the PMA acts as a load and radiator to the chaotic oscillator. By changing the bias voltage of the oscillator, the antenna can be made to operate at single or multiple frequencies. To test the characteristics of the antenna at single and multiple frequencies of operation, two similar prototype models of printed monopole broadband antennas are developed. One of these antennas used at transmit side is fed by the chaotic Colpitts oscillator while the other is used as the receive antenna. It is observed that the antenna receives single or multiple frequencies simultaneously for particular values of the bias voltage of the oscillator at the transmit end.

  10. SMART SUSTAINABLE ISLANDS VS SMART SUSTAINABLE CITIES

    Directory of Open Access Journals (Sweden)

    D. N. Pantazis

    2017-09-01

    Full Text Available This paper has several aims: a the presentation of a critical analysis of the terms “smart sustainable cities” and “smart sustainable islands” b the presentation of a number of principles towards to the development methodological framework of concepts and actions, in a form of a manual and actions guide, for the smartification and sustainability of islands. This kind of master plan is divided in thematic sectors (key factors which concern the insular municipalities c the creation of an island’s smartification and sustainability index d the first steps towards the creation of a portal for the presentation of our smartification actions manual, together with relative resources, smart applications examples, and, in the near future the first results of our index application in a number of Greek islands and e the presentation of some proposals of possible actions towards their sustainable development and smartification for the municipalities - islands of Paros and Antiparos in Greece, as case studies.

  11. A family of memristor-based reactance-less oscillators

    KAUST Repository

    Zidan, Mohammed A.

    2013-05-03

    In this paper, we present for the first time a family of memristor-based reactance-less oscillators (MRLOs). The proposed oscillators require no reactive components, that is, inductors or capacitors, rather, the ‘resistance storage’ property of memristor is exploited to generate the oscillation. Different types of MRLO family are presented, and for each type, closed form expressions are derived for the oscillation condition, oscillation frequency, and range of oscillation. Derived equations are further verified using transient circuit simulations. A comparison between different MRLO types is also discussed. In addition, detailed fabrication steps of a memristor device and experimental results for the first MRLO physical realization are presented.

  12. State space modeling of Memristor-based Wien oscillator

    KAUST Repository

    Talukdar, Abdul Hafiz Ibne

    2011-12-01

    State space modeling of Memristor based Wien \\'A\\' oscillator has been demonstrated for the first time considering nonlinear ion drift in Memristor. Time dependant oscillating resistance of Memristor is reported in both state space solution and SPICE simulation which plausibly provide the basis of realizing parametric oscillation by Memristor based Wien oscillator. In addition to this part Memristor is shown to stabilize the final oscillation amplitude by means of its nonlinear dynamic resistance which hints for eliminating diode in the feedback network of conventional Wien oscillator. © 2011 IEEE.

  13. Frequency stabilization in nonlinear MEMS and NEMS oscillators

    Science.gov (United States)

    Lopez, Omar Daniel; Antonio, Dario

    2014-09-16

    An illustrative system includes an amplifier operably connected to a phase shifter. The amplifier is configured to amplify a voltage from an oscillator. The phase shifter is operably connected to a driving amplitude control, wherein the phase shifter is configured to phase shift the amplified voltage and is configured to set an amplitude of the phase shifted voltage. The oscillator is operably connected to the driving amplitude control. The phase shifted voltage drives the oscillator. The oscillator is at an internal resonance condition, based at least on the amplitude of the phase shifted voltage, that stabilizes frequency oscillations in the oscillator.

  14. Sustainable Building Operation

    DEFF Research Database (Denmark)

    Jensen, Jesper Ole

    2009-01-01

    Energy-savings in the existing building stock have becomes a main goal in national and international policies. Often focus is on building-renovations, whereas the potential of sustainable building operation to a large extent has been neglected. Nevertheless, international research as well...... as practical experiences from Danish housing estates indicates that there are large potentials for energy savings by focusing on the operation of the buildings. We suggest that in order to achieve sustainability in the existing housing, renovation and operations should be seen as integrated parts...... and that sustainable building operation can pave the way for sustainable building renovation. This paper discusses the use of sustainability building operation in Danish housing estates: Which tools, methods and technologies is being used, where are the barriers and where are the potentials? We define sustainable...

  15. Health and Sustainability

    DEFF Research Database (Denmark)

    Land, Birgit; Pedersen, Kirsten Bransholm; Kjærgård, Bente

    2014-01-01

    In the present article, we explore how sustainable development strategies and health promotion strategies can be bridged. The concept of the ‘duality of structure’ is taken as our starting point for understanding the linkages between health promotion and sustainable development, and for uncovering...... the structural properties or conditions which either enable or constrain sustainable public health initiatives. We argue that strategies towards health promotion are not sufficiently integrated with strategies for sustainable development, and thus political strategies aimed at solving health problems...... or sustainability problems may cause new, undesired and unforeseen environmental or health problems. First, we explore how the relation between health and sustainability is articulated in international policy documents. Next, we develop a model for understanding the relation between health promotion...

  16. Sustainability and Entrepreneurial Action

    DEFF Research Database (Denmark)

    Korsgaard, Steffen T.; Anderson, Alistair

    Abstract Objectives - This paper explores how entrepreneurial action can lead to environmental sustainability. It builds on the assumption that the creation of sustainble practices is one of the most important challenges facing the global society, and that entrepreneurial action is a vital...... instrument in the pursuit of sustainability.  Prior Work - Extant literature identifies two main approaches to sustainable entrepreneurship. (i) traditional exploitation of environmentally relevant opportunities and (ii) institutional entrepreneurship creating opportunities. We identify a novel form......: resource oriented sustainable entrepreneurial action.  Approach - The paper uses a case study approach to build deeper theoretical knowledge of environmentally sustainable entrepreneurship.  Results - The paper identifies and analyses a distinct form of sustainable entrepreneurship -  resource oriented...

  17. At Home with Sustainability

    DEFF Research Database (Denmark)

    Hale, Lara

    2018-01-01

    of default rules in subconscious decision-making, this research finds that, ultimately, awareness drives the demand necessary for the creation of sustainable consumption. Whereas direct appeal to individuals has a disappointing level of influence on sustainability choices, it is understood that green......-fuel-based energy. To act otherwise requires additional effort and is less likely. Motivated by a need to understand how defaults might bridge standards and sustainable consumption, I investigate how organizational processes potentially lead from standardized green default rules to individual awareness that can...... spread and facilitate sustainable consumption. This paper examines the Active House sustainable building demonstrations in Europe in order to understand how (1) communications and market creation and (2) responsible, user-centered experimentation are organized to move from defaults to sustainable...

  18. ICT innovations for sustainability

    CERN Document Server

    Aebischer, Bernard

    2015-01-01

    ICT Innovations for Sustainability is an investigation of how information and communication technology can contribute to sustainable development. It presents clear definitions of sustainability, suggesting conceptual frameworks for the positive and negative effects of ICT on sustainable development. It reviews methods of assessing the direct and indirect impact of ICT systems on energy and materials demand, and examines the results of such assessments. In addition, it investigates ICT-based approaches to supporting sustainable patterns of production and consumption, analyzing them at various levels of abstraction – from end-user devices, Internet infrastructure, user behavior, and social practices to macro-economic indicators.   Combining approaches from Computer Science, Information Systems, Human-Computer Interaction, Economics, and Environmental Sciences, the book presents a new, holistic perspective on ICT for Sustainability (ICT4S). It is an indispensable resource for anyone working in the area of ICT...

  19. Sustainability and substitutability.

    Science.gov (United States)

    Fenichel, Eli P; Zhao, Jinhua

    2015-02-01

    Developing a quantitative science of sustainability requires bridging mathematical concepts from fields contributing to sustainability science. The concept of substitutability is central to sustainability but is defined differently by different fields. Specifically, economics tends to define substitutability as a marginal concept while fields such as ecology tend to focus on limiting behaviors. We explain how to reconcile these different views. We develop a model where investments can be made in knowledge to increase the elasticity of substitution. We explore the set of sustainable and optimal trajectories for natural capital extraction and built and knowledge capital accumulation. Investments in substitutability through knowledge stock accumulation affect the value of natural capital. Results suggest that investing in the knowledge stock, which can enhance substitutability, is critical to desirable sustainable outcomes. This result is robust even when natural capital is not managed optimally. This leads us to conclude that investments in the knowledge stock are of first order importance for sustainability.

  20. Sustainable Concrete Technology

    Directory of Open Access Journals (Sweden)

    Sim J.

    2015-12-01

    Full Text Available The growing concern over global warming and significant ecological changes requires sustainable development in all fields of science and technology. Concrete not only consumes huge amount of energy and natural sources, but also emits large amount of CO2, mainly due to the production of cement. It is evident that such large amount of concrete production has put significant impact on the energy, resource, environment, and ecology of the society. Hence, how to develop the concrete technology in a sustainable way has become a significant issue. In this paper, some of Korean researches for sustainable development of concrete are presented. These are sustainable strengthening for deteriorated concrete structure, sustainable reinforcement of new concrete structure, sustainable concrete using recycled aggregate and supplementary cementing materials and finally application of each technique to precast concrete.

  1. Representation of Cognitive Reappraisal Goals in Frontal Gamma Oscillations

    Science.gov (United States)

    Kang, Jae-Hwan; Jeong, Ji Woon; Kim, Hyun Taek; Kim, Sang Hee; Kim, Sung-Phil

    2014-01-01

    Recently, numerous efforts have been made to understand the neural mechanisms underlying cognitive regulation of emotion, such as cognitive reappraisal. Many studies have reported that cognitive control of emotion induces increases in neural activity of the control system, including the prefrontal cortex and the dorsal anterior cingulate cortex, and increases or decreases (depending upon the regulation goal) in neural activity of the appraisal system, including the amygdala and the insula. It has been hypothesized that information about regulation goals needs to be processed through interactions between the control and appraisal systems in order to support cognitive reappraisal. However, how this information is represented in the dynamics of cortical activity remains largely unknown. To address this, we investigated temporal changes in gamma band activity (35–55 Hz) in human electroencephalograms during a cognitive reappraisal task that was comprised of three reappraisal goals: to decease, maintain, or increase emotional responses modulated by affect-laden pictures. We examined how the characteristics of gamma oscillations, such as spectral power and large-scale phase synchronization, represented cognitive reappraisal goals. We found that left frontal gamma power decreased, was sustained, or increased when the participants suppressed, maintained, or amplified their emotions, respectively. This change in left frontal gamma power appeared during an interval of 1926 to 2453 ms after stimulus onset. We also found that the number of phase-synchronized pairs of gamma oscillations over the entire brain increased when participants regulated their emotions compared to when they maintained their emotions. These results suggest that left frontal gamma power may reflect cortical representation of emotional states modulated by cognitive reappraisal goals and gamma phase synchronization across whole brain regions may reflect emotional regulatory efforts to achieve these goals

  2. Sustainable fashion: New approaches

    OpenAIRE

    Niinimäki, Kirsi

    2013-01-01

    This publication is intended to be used as a source of inspiration for designers and companies, and all stakeholders whose interest lies in the area of sustainable fashion. While the strategies for sustainability are complex and approaches are many, this publication presents only a few ways to approach sustainable fashion. I hope the publication offers inspiration on how to make positive change in current practices and how to effect new mindsets, creating transformative fashion. Theoretica...

  3. Education for sustainable development

    DEFF Research Database (Denmark)

    Breiting, Søren

    2009-01-01

     An introduction to the idea of sustainable development (SD) and education for sustainable development (ESD) with reference to the international Decade for Education for Sustainable Development . The chapter includes a focus on conflicting interests between present and future generations related...... to the use of natural resources and other matters, and how that kind of issues can be dealt with in education as ESD....

  4. A highly sustainable house

    OpenAIRE

    Cordero, Raúl; Mercader-Moyano, Pilar (Coordinador)

    2017-01-01

    A sustainable house is capable of generating and self-sustaining energy by itself to function autonomously, that is to say, without depending on external supply networks. That is possible by supplying the internal energy consumption through renewable energy. This work describes and analyzes the construction of a sustainable house in Paute, Ecuador. The goal of this house was to achieve selfsustainability in several aspects such as construction techniques, creative and functi...

  5. Sustainability Assessment Circle

    OpenAIRE

    Schlör, H.; Hake, J.-Fr.

    2015-01-01

    Since the nineteen seventies, science and society have been discussing the worldwide ecological, economic, and social problems caused by industrialization and globalization. Sustainable development is perceived as a strategy for coping with these problems. The Rio +20 conference in 2012 confirmed the sustainability concept and introduced the green economy and the life cycle sustainable assessment as its implementation and operationalization strategy and tool.In the following, we will demonstr...

  6. Ka Band Phase Locked Loop Oscillator Dielectric Resonator Oscillator for Satellite EHF Band Receiver

    Directory of Open Access Journals (Sweden)

    S. Coco

    2008-01-01

    Full Text Available This paper describes the design and fabrication of a Ka Band PLL DRO having a fundamental oscillation frequency of 19.250 GHz, used as local oscillator in the low-noise block of a down converter (LNB for an EHF band receiver. Apposite circuital models have been created to describe the behaviour of the dielectric resonator and of the active component used in the oscillator core. The DRO characterization and measurements have shown very good agreement with simulation results. A good phase noise performance is obtained by using a very high Q dielectric resonator.

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

    Science.gov (United States)

    Rutenberg, Andrew; Sengupta, Supratim; Sain, Anirban; Derr, Julien

    2011-03-01

    We present a computational model of the E. coli Min oscillation that involves polymerization of MinD filaments followed by depolymerization stimulated by filament-end zones of MinE. Our stochastic model is fully three-dimensional, and tracks the diffusion and interactions of every MinD and MinE molecule. We recover self-organized Min oscillations. We investigate the experimental phenomenon of oscillation stuttering, which we relate to the disruption of MinE tip-binding at the filament scale.

  8. Synchronization of an optomechanical oscillator and thermal/free-carrier self-pulsing using optical comb forces

    CERN Document Server

    Navarro-Urrios, Daniel; Gomis-Bresco, Jordi; Alzina, Francesc; Griol, Amadeu; Martinez, Alejandro; Torres, Clivia M Sotomayor

    2014-01-01

    Optical forces can set tiny objects in states of self-sustained oscillation. When more than one oscillator comes into play, even a very weak interaction among them may lead to synchronization. This work reports a novel spontaneous synchronization process within an optomechanical crystal, which involves thermal/free-carrier self-pulsing and coherent mechanical motion. Both oscillating systems are driven and coupled by the optical energy stored in the cavity. Multiple frequency entrainment regions are observed as a result of the wide tuneability of the natural frequency of the thermal/free-carrier self-pulsing and the comb nature of the optical forces. All these features are observed at ambient conditions of pressure and temperature in a silicon compatible platform, which would allow their exploitation for advanced clocking applications or in artificial neural networks.

  9. Sustainability assessment and complementarity

    Directory of Open Access Journals (Sweden)

    Hugo F. Alrøe

    2016-03-01

    Full Text Available Sustainability assessments bring together different perspectives that pertain to sustainability to produce overall assessments, and a wealth of approaches and tools have been developed in the past decades. However, two major problems remain. The problem of integration concerns the surplus of possibilities for integration; different tools produce different assessments. The problem of implementation concerns the barrier between assessment and transformation; assessments do not lead to the expected changes in practice. We aim to analyze issues of complementarity in sustainability assessment and transformation as a key to better handling the problems of integration and implementation. Based on a generalization of Niels Bohr's complementarity from quantum mechanics, we have identified two forms of complementarity in sustainability assessment, observer stance complementarity and value complementarity. Unlike many other problems of sustainability assessment, complementarity is of a fundamental character connected to the very conditions for observation. Therefore, complementarity cannot be overcome methodologically, only handled better or worse. Science is essential to the societal goal of sustainability, but these issues of complementarity impede the constructive role of science in the transition to more sustainable structures and practices in food systems. The agencies of sustainability assessment and transformation need to be acutely aware of the importance of different perspectives and values and the complementarities that may be connected to these differences. An improved understanding of complementarity can help to better recognize and handle issues of complementarity. These deliberations have relevance not only for sustainability assessment, but more generally for transdisciplinary research on wicked problems.

  10. Predicting Sustainable Work Behavior

    DEFF Research Database (Denmark)

    Hald, Kim Sundtoft

    2013-01-01

    . Employee characteristics and general attitudes towards safety and work condition are included in the extended model. A survey was handed out to 654 employees in Chinese factories. This research contributes by demonstrating how employee- characteristics and general attitudes towards safety and work...... condition influence their sustainable work behavior. A new definition of sustainable work behavior is proposed.......Sustainable work behavior is an important issue for operations managers – it has implications for most outcomes of OM. This research explores the antecedents of sustainable work behavior. It revisits and extends the sociotechnical model developed by Brown et al. (2000) on predicting safe behavior...

  11. Sustainability needs the geosciences

    Science.gov (United States)

    Grimm, Nancy; van der Pluijm, Ben

    2012-10-01

    Science, Innovation, and Partnerships for Sustainable Solutions: A National Academies Symposium; Washington, D. C., 16-18 May 2012 It is no longer disputed that humanity has drastically changed the face of the planet and its life-support systems. The sustainability challenge is to meet people's needs today and in the future while sustaining life-support systems. This grand challenge demands a new scientific approach: use-inspired, solution-driven research that consciously links scientific research to societal decision-making and action. Sustainability science may help fulfill that need if it can engage communities of expertise across a wide range of disciplines and sectors, including the geosciences.

  12. Sustainable wireless networks

    CERN Document Server

    Zheng, Zhongming; Xuemin

    2013-01-01

    This brief focuses on network planning and resource allocation by jointly considering cost and energy sustainability in wireless networks with sustainable energy. The characteristics of green energy and investigating existing energy-efficient green approaches for wireless networks with sustainable energy is covered in the first part of this brief. The book then addresses the random availability and capacity of the energy supply. The authors explore how to maximize the energy sustainability of the network and minimize the failure probability that the mesh access points (APs) could deplete their

  13. Sustainable Management of Food

    Science.gov (United States)

    To provide information to organizations to help them implement sustainable food management, including joining the Food Recovery Challenge. To provide education and information to communities and concerned citizens.

  14. Nonlinear dynamics in micromechanical and nanomechanical resonators and oscillators

    Science.gov (United States)

    Dunn, Tyler

    dynamics in passive resonators, self-sustained MEMS are becoming increasingly prevalent in both research and technology for crucial objectives, such as measurement of time. Despite some effort, much work remains in order to understand phase noise and stability for an oscillator based upon a nonlinear resonator. With the eventual goal of making comprehensive measurements of such a nonlinear oscillator with controlled amplitude and phase, this work describes the realization of a micromechanical phase feedback oscillator.

  15. Roles of protein ubiquitination and degradation kinetics in biological oscillations.

    Directory of Open Access Journals (Sweden)

    Lida Xu

    Full Text Available Protein ubiquitination and degradation play important roles in many biological functions and are associated with many human diseases. It is well known that for biochemical oscillations to occur, proper degradation rates of the participating proteins are needed. In most mathematical models of biochemical reactions, linear degradation kinetics has been used. However, the degradation kinetics in real systems may be nonlinear, and how nonlinear degradation kinetics affects biological oscillations are not well understood. In this study, we first develop a biochemical reaction model of protein ubiquitination and degradation and calculate the degradation rate against the concentration of the free substrate. We show that the protein degradation kinetics mainly follows the Michaelis-Menten formulation with a time delay caused by ubiquitination and deubiquitination. We then study analytically how the Michaelis-Menten degradation kinetics affects the instabilities that lead to oscillations using three generic oscillation models: 1 a positive feedback mediated oscillator; 2 a positive-plus-negative feedback mediated oscillator; and 3 a negative feedback mediated oscillator. In all three cases, nonlinear degradation kinetics promotes oscillations, especially for the negative feedback mediated oscillator, resulting in much larger oscillation amplitudes and slower frequencies than those observed with linear kinetics. However, the time delay due to protein ubiquitination and deubiquitination generally suppresses oscillations, reducing the amplitude and increasing the frequency of the oscillations. These theoretical analyses provide mechanistic insights into the effects of specific proteins in the ubiquitination-proteasome system on biological oscillations.

  16. ROBUST CONTROL OF OSCILLATIONS IN AGRICULTURAL TRACTORS

    DEFF Research Database (Denmark)

    Andersen, T. O.; Hansen, M. R.; Conrad, Finn

    2003-01-01

    for agricultural tractors equiped with hicth and implements. A control strategy is developed to make the implement counteract the movement of the tractor and thereby reducing the pitching oscillation. The control strategy is based on a linear plant model with constant or slowly varying parameters. Using...

  17. Influence of core electrons on plasmon oscillations

    Science.gov (United States)

    Lipparini, E.; Pederiva, Francesco

    1993-09-01

    Core electrons constitute a polarizable background which tends to screen the plasma oscillations. The influence of core electrons on plasmon dispersion is studied with sum rule techniques. Analytical expressions are derived for the surface plasmon of flat surfaces and of small metal particles. Core polarization explains semiquantitatively the blue-shift of the surface plasmon recently observed in silver systems.

  18. Control of partial synchronization in chaotic oscillators

    Indian Academy of Sciences (India)

    2015-02-07

    Feb 7, 2015 ... Abstract. A design of coupling is proposed to control partial synchronization in two chaotic oscil- lators in a driver–response mode. A control of synchrony between one response variables is made possible (a transition from a complete synchronization to antisynchronization via amplitude death and vice ...

  19. Liquid Oscillations in a U-Tube

    Science.gov (United States)

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco; Navarro, Luis Barba

    2018-01-01

    In hydrostatics, pressure measurement with U-gauges and their relationship to density is a well-known experiment. Very little is studied or experimented with the dynamics of the movement of a liquid in a U-tube probably due to its theoretical complexity but, after all, it is a simple damped oscillating system. In this paper we present a relatively…

  20. Synchronization of oscillators in complex networks

    Indian Academy of Sciences (India)

    This being the most conservative assumption will cover the largest class of oscillators including those which have multiple, disjoint α regions of stability as can ..... intake of food and energy which will be fruitful only if the new networks are a great improvement and provide the organisms some evolutionary advantages. In.

  1. Parametric resonance in neutrino oscillations in matter

    Indian Academy of Sciences (India)

    simple exact analytic solution. We will discuss this solution in Д6Д 2 and 4. ..... metric resonance conditions with respect to variations of the nadir angle – has a simple explanation. It is related to the fact that, due to ..... see [8,17,18]. The analogy with a pendulum with vertically oscillating point of support was discussed in [11].

  2. Chemical Oscillations-Basic Principles and Examples

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 2. Chemical Oscillations - Basic Principles and Examples ... Protein Science and Engineering Unit Institute of Microbial Technology Sector 39A Chandigarh 160 036; Department of Chemistry and Centre for Advanced Studies in Chemistry ...

  3. Information cloning of harmonic oscillator coherent states

    Indian Academy of Sciences (India)

    Abstract. We show that in the case of unknown harmonic oscillator coherent states it is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state.

  4. Acoustic power measurements of oscillating flames

    NARCIS (Netherlands)

    Valk, M.

    1981-01-01

    The acoustic power of an oscillating flame is measured. A turbulent premixed propane/air flame is situated near a pressure antinode of a standing wave in a laboratory combustion chamber. This standing wave is generated by a piston. The fluctuating heat release of the flame will supply acoustic power

  5. Page 1 Anharmonic oscillators Acknowledgements Financial ...

    Indian Academy of Sciences (India)

    Anharmonic oscillators. Acknowledgements. Financial assistance of CSIR, India, is gratefully acknowledged. One of us (AKC) is also thankful to CSIR for providing a research associateship. References. 1 G Herzberg, Molecular spectra and molecular structure (Van Nostrand Reinhold, NY,. 1950) Vol 1. 2 C Kittel ...

  6. On entanglement in neutrino mixing and 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)

    2010-06-01

    We report on recent results about entanglement in the context of particle mixing and oscillations. We study in detail single-particle entanglement arising in two-flavor neutrino mixing. The analysis is performed first in the context of Quantum Mechanics, and then for the case of Quantum Field Theory.

  7. Hyperchaotic circuit with damped harmonic oscillators

    DEFF Research Database (Denmark)

    Lindberg, Erik; Murali, K.; Tamasevicius, A.

    2001-01-01

    A simple fourth-order hyperchaotic circuit with damped harmonic oscillators is described. ANP3 and PSpice simulations including an eigenvalue study of the linearized Jacobian are presented together with a hardware implementation. The circuit contains two inductors with series resistance, two ideal...

  8. Information cloning of harmonic oscillator coherent states

    Indian Academy of Sciences (India)

    We show that in the case of unknown harmonic oscillator coherent statesit is possible to achieve what we call perfect information cloning. By this we mean that it is still possible to make arbitrary number of copies of a state which has exactly the same information content as the original unknown coherent state. By making use ...

  9. Accelerator-based neutrino oscillation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Harris, Deborah A.; /Fermilab

    2007-12-01

    Neutrino oscillations were first discovered by experiments looking at neutrinos coming from extra-terrestrial sources, namely the sun and the atmosphere, but we will be depending on earth-based sources to take many of the next steps in this field. This article describes what has been learned so far from accelerator-based neutrino oscillation experiments, and then describe very generally what the next accelerator-based steps are. In section 2 the article discusses how one uses an accelerator to make a neutrino beam, in particular, one made from decays in flight of charged pions. There are several different neutrino detection methods currently in use, or under development. In section 3 these are presented, with a description of the general concept, an example of such a detector, and then a brief discussion of the outstanding issues associated with this detection technique. Finally, section 4 describes how the measurements of oscillation probabilities are made. This includes a description of the near detector technique and how it can be used to make the most precise measurements of neutrino oscillations.

  10. Recurring events. Power oscillations in BWRs

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-12-01

    During almost two decennia, the recurrence of power oscillations in domestic and foreign BWRs has represented a challenge to one important design safety criterion, even if the occurred power oscillations have not resulted in conditions exceeding the specified fuel design limits. Several reasons may explain the recurrence. One reason has been a worldwide trend for an aggressive fuel economy optimisation, which from time to another has resulted in reduced core stability margins. Another reason relates to the analytical tools for prediction of core stability. These tools were scarce during many years. A third aspect is that adequate and reliable core monitors were not early available for installation at the plants. Issues related to power oscillations have during many years received attention from both the regulatory body and utilities, and from the fuel manufacturers. The present report provides examples of important corrective actions which support this conclusion. However, recent events indicate that the complex issue of BWR power oscillations has not been suitably solved, at least domestically.

  11. A common oscillator for perceptual rivalries?

    Science.gov (United States)

    Carter, Olivia L; Pettigrew, John D

    2003-01-01

    Perceptual rivalry is an oscillation of conscious experience that takes place despite univarying. if ambiguous, sensory input. Much current interest is focused on the controversy over the neural site of binocular rivalry, a variety of perceptual rivalry for which a number of different cortical regions have been implicated. Debate continues over the relative role of higher levels of processing compared with primary visual cortex and the suggestion that different forms of rivalry involve different cortical areas. Here we show that the temporal pattern of disappearance and reappearance in motion-induced blindness (MIB) (Bonneh et al, 2001 Nature 411 798-801) is highly correlated with the pattern of oscillation reported during binocular rivalry in the same individual. This correlation holds over a wide range of inter-individual variation. Temporal similarity in the two phenomena was strikingly confirmed by the effects of the hallucinogen LSD, which produced the same, extraordinary, pattern of increased rhythmicity in both kinds of perceptual oscillation. Furthermore. MIB demonstrates the two properties previously considered characteristic of binocular rivalry. Namely the distribution of dominance periods can be approximated by a gamma distribution and, in line with Levelt's second proposition of binocular rivalry, predominance of one perceptual phase can be increased through a reduction in the predominance time of the opposing phase. We conclude that (i) MIB is a form of perceptual rivalry, and (ii) there may be a common oscillator responsible for timing aspects of all forms of perceptual rivalry.

  12. The strange case of the "oscillating" catalysts

    NARCIS (Netherlands)

    Busico, [No Value; Cipullo, R; Kretschmer, W; Talarico, G; Vacatello, M; Castelli, VV

    2002-01-01

    The field of stereoselective propene polymerization has been dramatically innovated by the discovery of homogeneous metallocene-based catalysts with well-defined and tunable molecular structure. Of all, "oscillating" metallocenes are probably the most ingenious and challenging example of catalyst

  13. Novel candidate genes associated with hippocampal oscillations.

    NARCIS (Netherlands)

    Jansen, R.; Timmerman, J.; Loos, M.; Spijker, S.; van Ooyen, A.; Brussaard, A.B.; Mansvelder, H.D.; Smit, A.B.; de Gunst, M.; Linkenkaer-Hansen, K.

    2011-01-01

    The hippocampus is critical for a wide range of emotional and cognitive behaviors. Here, we performed the first genome-wide search for genes influencing hippocampal oscillations. We measured local field potentials (LFPs) using 64-channel multi-electrode arrays in acute hippocampal slices of 29 BXD

  14. Self-oscillating inverter with bipolar transistors

    Science.gov (United States)

    Baciu, I.; Cunţan, C. D.; Floruţa, M.

    2016-02-01

    The paper presents a self-oscillating inverter manufactured with bipolar transistors that supplies a high-amplitude alternating voltage to a fluorescent tube with a burned filament. The inverter is supplied from a low voltage accumulator that can be charged from a photovoltaic panel through a voltage regulator.

  15. Neutrino oscillations: Recent results and future directions

    Indian Academy of Sciences (India)

    A brief introduction to the phenomena of vacuum neutrino oscillations and resonant flavour conversion is presented with a heavy pedagogic leaning. Variants of these ideas, e.g., neutrino helicity flip in a magnetic field, violation of the equivalence principle, etc. are outlined. A few vexing issues pertaining to the quantum ...

  16. Sobolev spaces associated to the harmonic oscillator

    Indian Academy of Sciences (India)

    2Departamento de Matemática, Facultad de Ciencias, Universidad Autónoma de. Madrid, Spain. E-mail: bbongio@math.unl.edu.ar; joseluis.torrea@uam.es. MS received 27 September 2005. Abstract. We define the Hermite–Sobolev spaces naturally associated to the harmonic oscillator H = − + |x|2. Structural properties ...

  17. Exponentially tapered Josephson flux-flow oscillator

    DEFF Research Database (Denmark)

    Benabdallah, A.; Caputo, J. G.; Scott, Alwyn C.

    1996-01-01

    We introduce an exponentially tapered Josephson flux-flow oscillator that is tuned by applying a bias current to the larger end of the junction. Numerical and analytical studies show that above a threshold level of bias current the static solution becomes unstable and gives rise to a train of flu...

  18. Control of partial synchronization in chaotic oscillators

    Indian Academy of Sciences (India)

    2015-02-07

    Feb 7, 2015 ... A design of coupling is proposed to control partial synchronization in two chaotic oscillators in a driver–response mode. ... Department of Mathematics, University of Technology and Management, Shillong 793 003, India; Central Instrumentation Division, CSIR-Indian Institute of Chemical Biology, Kolkata ...

  19. CHAOTIC DUFFING TYPE OSCILLATOR WITH INERTIAL DAMPING

    DEFF Research Database (Denmark)

    Tamaševicius, Arunas; Mykolaitis, Gytis; Kirvaitis, Raimundas

    2009-01-01

    A novel Duffing-Holmes type autonomous chaotic oscillator is described. In comparison with the well-known non-autonomous Duffing-Holmes circuit it lacks the external periodic drive, but includes two extra linear feedback sub-circuits, namely a direct positive feedback loop, and an inertial negative...... feedback loop. SPICE simulation and hardware experimental results are presented....

  20. Seasonality and mechanisms of tropical intraseasonal oscillations

    Science.gov (United States)

    Hazra, Abheera; Krishnamurthy, V.

    2018-01-01

    This study has compared the monsoon intraseasonal oscillation (MISO) during the boreal summer and Madden Julian Oscillation (MJO) during the boreal winter. Based on MISO and MJO in high-resolution three-dimensional diabatic heating, the possible mechanisms are discussed through observational analyses of dynamical and thermodynamical variables. The MISO and MJO are extracted as nonlinear oscillations during boreal summer and winter, respectively, by applying multi-channel singular spectrum analysis on daily anomalies of diabatic heating over the Indo-Pacific region. Lead and lag relations among moisture, temperature and surface fields relative to diabatic heating are analyzed to compare the mechanisms of MISO and MJO. While both the oscillations show eastward propagation, MISO has a strong northward propagation and MJO has a weak southward propagation as well. The analysis shows that MJO and MISO are essentially driven by the same mechanisms but with some difference in the meridional propagation. The westerly shear leads the diabatic heating, while the vorticity has weak correlation. Large-scale circulation creates positive moisture preconditioning before convection and negative moisture preconditioning before suppressed conditions. A positive lower level horizontal advection of temperature and upper level temperature tendencies lead the convective state while a negative lower level horizontal advection of temperature and upper level temperature tendencies lead the suppressed state. There is positive feedback from the SST to atmosphere. The difference in the meridional propagation of MISO and MJO is hypothesized to be because of the different differential heating meridionally during the two seasons.