Inner Retinal Oxygen Extraction Fraction in Response to Light Flicker Stimulation in Humans

Science.gov (United States)

Felder, Anthony E.; Wanek, Justin; Blair, Norman P.; Shahidi, Mahnaz

2015-01-01

Purpose Light flicker has been shown to stimulate retinal neural activity, increase blood flow, and alter inner retinal oxygen metabolism (MO2) and delivery (DO2). The purpose of the study was to determine the change in MO2 relative to DO2 due to light flicker stimulation in humans, as assessed by the inner retinal oxygen extraction fraction (OEF). Methods An optical imaging system, based on a modified slit lamp biomicroscope, was developed for simultaneous measurements of retinal vascular diameter (D) and oxygen saturation (SO2). Retinal images were acquired in 20 healthy subjects before and during light flicker stimulation. Arterial and venous D (DA and DV) and SO2 (SO2A and SO2V) were quantified within a circumpapillary region. Oxygen extraction fraction was defined as the ratio of MO2 to DO2 and was calculated as (SO2A − SO2V)/SO2A. Reproducibility of measurements was assessed. Results Coefficients of variation and intraclass correlation coefficients of repeated measurements were <5% and ≥0.83, respectively. During light flicker stimulation, DA, DV , and SO2V significantly increased (P ≤ 0.004). Oxygen extraction fraction was 0.37 ± 0.08 before light flicker and significantly decreased to 0.31 ± 0.07 during light flicker (P = 0.001). Conclusions Oxygen extraction fraction before and during light flicker stimulation is reported in human subjects for the first time. Oxygen extraction fraction decreased during light flicker stimulation, indicating the change in DO2 exceeded that of MO2. This technology is potentially useful for the detection of changes in OEF response to light flicker in physiological and pathological retinal conditions. PMID:26469748

Flicker Detection, Measurement and Means of Mitigation: A Review

Science.gov (United States)

Virulkar, V. B.; Aware, M. V.

2014-04-01

The voltage fluctuations caused by rapid industrial load change have been a major concern for supply utilities, regulatory agencies and customers. This paper gives a general review about how to examine/assess voltage flicker and methods followed in measuring the flickers due to rapid changing loads and means for its mitigation. It discusses the effects on utilities conditions, compensators response time and compensator capacity of flicker mitigation. A comparison between conventional mitigation techniques and the state-of-art mitigation techniques are carried out. It is shown in many cases that the state-of-art solution provides higher performance compared with conventional mitigation techniques. However, the choice of most suitable solution depends on characteristics of the supply at the point of connection, the requirement of the load and economics.

Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

Directory of Open Access Journals (Sweden)

Yanting Hu

2013-07-01

Full Text Available Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution power oscillation due to wind shear and tower shadow effects is the significant part in the flicker emission of variable speed wind turbines with PMSG during continuous operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.

Impact of co-flow air on buoyant diffusion flames flicker

Energy Technology Data Exchange (ETDEWEB)

Gohari Darabkhani, H., E-mail: h.g.darabkhani@gmail.com [School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL (United Kingdom); Wang, Q.; Chen, L.; Zhang, Y. [Mechanical Engineering Department, University of Sheffield, Mapping Street, Sheffield S1 3JD (United Kingdom)

2011-08-15

Highlights: {yields} We present the co-flow effects on flickering behaviour of diffusion flames. {yields} Co-flow air is shown to fully suppress the buoyancy driven flame oscillations. {yields} Schlieren and PIV illustrate the shift of outer vortices beyond the flame zone. {yields} Stability controlling parameter as a ratio of air to fuel velocities is presented. {yields} Equation for linear increase in flickering frequency by co-flow air is presented. - Abstract: This paper describes experimental investigation of co-flow air velocity effects on the flickering behaviour of laminar non-lifted methane diffusion flames. Chemiluminescence, high-speed photography, schlieren and Particle Imaging Velocimetry (PIV), have been used to study the changes in the flame/vortex interactions as well as the flame flickering frequency and magnitude by the co-flow air. Four cases of methane flow rates at different co-flow air velocities are investigated. It has been observed that the flame dynamics and stability of co-flow diffusion flames are strongly affected by the co-flow air velocity. When the co-flow velocity has reached a certain value the buoyancy driven flame oscillation was completely suppressed. The schlieren and PIV imaging have revealed that the co-flow of air is able to push the initiation point of the outer toroidal vortices beyond the visible flame to create a very steady laminar flow region in the reaction zone. Then the buoyancy driven instability is only effective in the plume of hot gases above the visible flame. It is observed that a higher co-flow rate is needed in order to suppress the flame flickering at a higher fuel flow rate. Therefore the ratio of the air velocity to the fuel velocity, {gamma}, is a stability controlling parameter. The velocity ratio, {gamma}, was found to be 0.72 for the range of tested flow rates. The dominant flickering frequency was observed to increase linearly with the co-flow rate (a) as; f = 0.33a + 11. The frequency amplitudes

Improved control system of the thyristor flicker suppressor for the KEK 12-GeV PS

International Nuclear Information System (INIS)

Matsumoto, S.; Baba, H.; Mikawa, K.; Sato, H.; Sueno, T.

1983-01-01

Thyristor control system of the 20 MVar flicker suppressor has been improved essentially. The previous feed forward (FF) loop with each single phase reactive current detector of the MR magnet power supply was exchanged to the present by both FF- and NFB-loops. The FF-loops consists of a three phase reactive power detector of the MPS and a forcing pattern generator on the fast but steady line voltage flicker, sag and surge. The NFB-loops control by the slow parts of the flicker and the unbalanced line voltages. These detectors of the reactive power, the voltage flicker and the unbalance have been developed. Sampled voltage flicker data with 12 bit ADC are processed by Z-80A micro computer system and the forcing pattern is generated by the system through 12 bit DAC into the loop. A typical voltage flicker including sag and surge has been reduced within + or - 1.5%, about 1/3 compared to the previous, at 66 kV primary line

EEG-based characterization of flicker perception

NARCIS (Netherlands)

Lazo, M.; Tsoneva, T.; Garcia Molina, G.

2013-01-01

Steady-State Visual Evoked Potential (SSVEP) is an oscillatory electrical response appearing in the electroencephalogram (EEG) in response to flicker stimulation. The SSVEP manifests more prominently in electrodes located near the visual cortex and has oscillatory components at the stimulation

Time sequence analysis of flickering auroras. I - Application of Fourier analysis. [in atmosphere

Science.gov (United States)

Berkey, F. T.; Silevitch, M. B.; Parsons, N. R.

1980-01-01

Using a technique that enables one to digitize the brightness of auroral displays from individual fields of a video signal, we have analyzed the frequency content of flickering aurora. Through the application of Fourier analysis to our data, we have found that flickering aurora contains a wide range of enhanced frequencies, although the dominant frequency enhancement generally occurs in the range 6-12 Hz. Each incidence of flickering that we observed was associated with increased radio wave absorption. Furthermore, we have found that flickering occurs in bright auroral surges, the occurrence of which is not limited to the 'breakup' phase of auroral substorms. Our results are interpreted in terms of a recently proposed theory of fluctuating double layers that accounts for a number of the observational features.

Analysis of the Flicker Level Produced by a Fixed-Speed Wind Turbine

Science.gov (United States)

Suppioni, Vinicius; P. Grilo, Ahda

2013-10-01

In this article, the analysis of the flicker emission during continuous operation of a mid-scale fixed-speed wind turbine connected to a distribution system is presented. Flicker emission is investigated based on simulation results, and the dependence of flicker emission on short-circuit capacity, grid impedance angle, mean wind speed, and wind turbulence is analyzed. The simulations were conducted in different programs in order to provide a more realistic wind emulation and detailed model of mechanical and electrical components of the wind turbine. Such aim is accomplished by using FAST (Fatigue, Aerodynamics, Structures, and Turbulence) to simulate the mechanical parts of the wind turbine, Simulink/MatLab to simulate the electrical system, and TurbSim to obtain the wind model. The results show that, even for a small wind generator, the flicker level can limit the wind power capacity installed in a distribution system.

Converter controls and flicker study of PMSG-based grid connected wind turbines

Directory of Open Access Journals (Sweden)

Ali H. Kasem Alaboudy

2013-03-01

Full Text Available With the increased penetration of wind power, the influence of wind turbine generators on the grid power quality stipulates careful investigation and analysis. Direct driven permanent magnet synchronous generator (PMSG with a back-to-back converter set is one of the promising technologies in wind power generation schemes. In this paper, comprehensive models of wind turbine are used to analyze power and voltage fluctuations. The short time flicker index is used to assess the voltage fluctuation emitted. The control scheme of the grid-side converter is supported with a voltage regulation loop to reduce flicker emission. The effects of grid and site parameters on voltage fluctuation are investigated. Simulation results show that reduced flicker emissions are given when the developed voltage regulation loop is activated. Reasonable values of grid and site parameters contribute in the minimization of voltage fluctuation and flicker emission levels.

The Amount of Time Dilation for Visual Flickers Corresponds to the Amount of Neural Entrainments Measured by EEG.

Science.gov (United States)

Hashimoto, Yuki; Yotsumoto, Yuko

2018-01-01

The neural basis of time perception has long attracted the interests of researchers. Recently, a conceptual model consisting of neural oscillators was proposed and validated by behavioral experiments that measured the dilated duration in perception of a flickering stimulus (Hashimoto and Yotsumoto, 2015). The model proposed that flickering stimuli cause neural entrainment of oscillators, resulting in dilated time perception. In this study, we examined the oscillator-based model of time perception, by collecting electroencephalography (EEG) data during an interval-timing task. Initially, subjects observed a stimulus, either flickering at 10-Hz or constantly illuminated. The subjects then reproduced the duration of the stimulus by pressing a button. As reported in previous studies, the subjects reproduced 1.22 times longer durations for flickering stimuli than for continuously illuminated stimuli. The event-related potential (ERP) during the observation of a flicker oscillated at 10 Hz, reflecting the 10-Hz neural activity phase-locked to the flicker. Importantly, the longer reproduced duration was associated with a larger amplitude of the 10-Hz ERP component during the inter-stimulus interval, as well as during the presentation of the flicker. The correlation between the reproduced duration and the 10-Hz oscillation during the inter-stimulus interval suggested that the flicker-induced neural entrainment affected time dilation. While the 10-Hz flickering stimuli induced phase-locked entrainments at 10 Hz, we also observed event-related desynchronizations of spontaneous neural oscillations in the alpha-frequency range. These could be attributed to the activation of excitatory neurons while observing the flicker stimuli. In addition, neural activity at approximately the alpha frequency increased during the reproduction phase, indicating that flicker-induced neural entrainment persisted even after the offset of the flicker. In summary, our results suggest that the

Impaired increase of retinal capillary blood flow to flicker light exposure in arterial hypertension.

Science.gov (United States)

Ritt, Martin; Harazny, Joanna M; Ott, Christian; Raff, Ulrike; Bauernschubert, Philipp; Lehmann, Marina; Michelson, Georg; Schmieder, Roland E

2012-09-01

We hypothesized that the increase of retinal capillary blood flow (RCF) to flicker light exposure is impaired in subjects with arterial hypertension. In 146 nondiabetic untreated male subjects with (n=50) or without (n=96) arterial hypertension, RCF was measured before and after flicker light exposure noninvasively and in vivo using scanning laser Doppler flowmetry. In addition, in a subgroup of 28 subjects, the change of RCF to flicker light exposure was again assessed during parallel infusion of nitric oxide synthase inhibitor N-monomethyl-L-arginine (L-NMMA). The increase of RCF to flicker light exposure was lower in patients with untreated hypertension compared with normotensive subjects when expressed in absolute terms (7.69±54 versus 27.2±44 AU; P adjusted=0.013) or percent changes (2.95±14 versus 8.33±12%; P adjusted=0.023). Systolic (β=-0.216; P=0.023) but not diastolic blood pressure (β=-0.117; P=0.243) or mean arterial pressure (β=-0.178; P=0.073) was negatively related to the percent change of RCF to flicker light exposure, independently of other cardiovascular risk factors. In the subgroup of 28 subjects, the increase of RCF to flicker light exposure was similar at baseline and during parallel infusion of L-NMMA when expressed in absolute terms (20.0±51 versus 22.6±56 AU; P=0.731) or percent changes (7.12±16 versus 8.29±18%; P=0.607). The increase of RCF to flicker light exposure is impaired in arterial hypertension. In the subgroup of the total study cohort, nitric oxide was not a major determinant of the increase of RCF to flicker light exposure.

Flicker-noise Spectroscopy In Earthquake Prediction Research

Science.gov (United States)

Desherevsky, A. V.; Lukk, A. A.; Sidorin, A. Y.; Timashev, S. F.

It has been found out that a two-component model including a seasonal and a flicker- noise components occurs to be a more adequate model of statistical structure of time series of long-term geophysical observations' data. Unlike a white noise which sig- nifies absence of any relation between the system's current dynamics and past events in it, presence of flicker-noise indicates that such a relation in the system does ex- ist. Flicker-noise pertains a property of scale invariance. It seems natural to relate self-similarity of statistical properties of geophysical parameters' variations on dif- ferent scales to self-similar (fractal) properties of geophysical medium. At the same time self-similar time variations of geophysical parameters may indicate to presence of deterministic chaos in geophysical system's evolution. An important element of a proposed approach is application of stochastic models of preparation of each concrete large seismic event. Instead of regular, for example bay-form precursor variations, occurrence of precursors of another kind associated in particular with variation in parameter fluctuations should be expected. To solve a problem of large earthquakes prediction we use Flicker-Noise Spectroscopy (FNS) as a basis of a new approach proposed by us. The basis of the FNS methodology is a postulate about the impor- tant information significance of sequences of various dynamic irregularities (bursts or spikes, jumps with different characteristic values, discontinuities of derivatives) of the measured temporal, spatial and energetic variables on each level of hierarchical orga- nization of studied systems. A proposed new method using integral values of analyzed signals - power spectra and different moments ("structural functions") of a different order as information relations, has demonstrated principally new opportunities in a search of large earthquake precursors already at a preliminary stage of some data analysis. This research was supported by

Flicker Mitigation by Individual Pitch Control of Variable Speed Wind Turbines With DFIG

DEFF Research Database (Denmark)

Zhang, Yunqian; Chen, Zhe; Hu, Weihao

2014-01-01

generatorto investigate the flicker emission and mitigation issues. An individual pitch control (IPC) strategy is proposed to reduce the flicker emission at different wind speed conditions. The IPC scheme is proposed and the individual pitch controller is designed according to the generator active power...... and the azimuth angle of the wind turbine. The simulations are performed on the NREL (National Renewable Energy Laboratory) 1.5-MW upwind reference wind turbine model. Simulation results show that damping the generator active power by IPC is an effective means for flicker mitigation of variable speed wind......Due to the wind speed variation, wind shear and tower shadow effects, grid connected wind turbines are the sources of power fluctuations which may produce flicker during continuous operation. This paper presents a model of an MW-level variable-speed wind turbine with a doubly fed induction...

Flicker Adaptation of Low-Level Cortical Visual Neurons Contributes to Temporal Dilation

Science.gov (United States)

Ortega, Laura; Guzman-Martinez, Emmanuel; Grabowecky, Marcia; Suzuki, Satoru

2012-01-01

Several seconds of adaptation to a flickered stimulus causes a subsequent brief static stimulus to appear longer in duration. Nonsensory factors, such as increased arousal and attention, have been thought to mediate this flicker-based temporal-dilation aftereffect. In this study, we provide evidence that adaptation of low-level cortical visual…

Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

DEFF Research Database (Denmark)

Hu, Weihao; Zhang, Yunqian; Chen, Zhe

2013-01-01

operation. A new method of flicker mitigation by controlling the rotational speed is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the rotational speed of the PMSG. Simulation results show that damping the 3p active power...... oscillation by using the flicker mitigation speed controller is an effective means for flicker mitigation of variable speed wind turbines with full-scale back-to-back power converters and PMSG during continuous operation.......Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG...

Flicker Mitigation by Active Power Control of Variable-Speed Wind Turbines With Full-Scale Back-to-Back Power Converters

DEFF Research Database (Denmark)

Hu, Weihao; Chen, Zhe; Wang, Zhaoan

2009-01-01

/EMTDC. Flicker emission of this system is investigated. Reactive power compensation is mostly adopted for flicker mitigation. However, the flicker mitigation technique shows its limits, when the grid impedance angle is low in some distribution networks. A new method of flicker mitigation by controlling active...... power is proposed. It smoothes the 3p active power oscillations from wind shear and tower shadow effects of the wind turbine by varying the dc-link voltage of the full-scale converter. Simulation results show that damping the 3p active power oscillation by using the flicker mitigation controller...... is an effective means for flicker mitigation of variable-speed wind turbines with full-scale back-to-back power converters during continuous operation....

Flicker Noise in GNSS Station Position Time Series: How much is due to Crustal Loading Deformations?

Science.gov (United States)

Rebischung, P.; Chanard, K.; Metivier, L.; Altamimi, Z.

2017-12-01

The presence of colored noise in GNSS station position time series was detected 20 years ago. It has been shown since then that the background spectrum of non-linear GNSS station position residuals closely follows a power-law process (known as flicker noise, 1/f noise or pink noise), with some white noise taking over at the highest frequencies. However, the origin of the flicker noise present in GNSS station position time series is still unclear. Flicker noise is often described as intrinsic to the GNSS system, i.e. due to errors in the GNSS observations or in their modeling, but no such error source has been identified so far that could explain the level of observed flicker noise, nor its spatial correlation.We investigate another possible contributor to the observed flicker noise, namely real crustal displacements driven by surface mass transports, i.e. non-tidal loading deformations. This study is motivated by the presence of power-law noise in the time series of low-degree (≤ 40) and low-order (≤ 12) Stokes coefficients observed by GRACE - power-law noise might also exist at higher degrees and orders, but obscured by GRACE observational noise. By comparing GNSS station position time series with loading deformation time series derived from GRACE gravity fields, both with their periodic components removed, we therefore assess whether GNSS and GRACE both plausibly observe the same flicker behavior of surface mass transports / loading deformations. Taking into account GRACE observability limitations, we also quantify the amount of flicker noise in GNSS station position time series that could be explained by such flicker loading deformations.

Removing flicker based on sparse color correspondences in old film restoration

Science.gov (United States)

Huang, Xi; Ding, Youdong; Yu, Bing; Xia, Tianran

2018-04-01

In the long history of human civilization, archived film is an indispensable part of it, and using digital method to repair damaged film is also a mainstream trend nowadays. In this paper, we propose a sparse color correspondences based technique to remove fading flicker for old films. Our model, combined with multi frame images to establish a simple correction model, includes three key steps. Firstly, we recover sparse color correspondences in the input frames to build a matrix with many missing entries. Secondly, we present a low-rank matrix factorization approach to estimate the unknown parameters of this model. Finally, we adopt a two-step strategy that divide the estimated parameters into reference frame parameters for color recovery correction and other frame parameters for color consistency correction to remove flicker. Our method combined multi-frames takes continuity of the input sequence into account, and the experimental results show the method can remove fading flicker efficiently.

Comparing the detection and agreement of parapapillary atrophy progression using digital optic disk photographs and alternation flicker.

Science.gov (United States)

VanderBeek, Brian L; Smith, Scott D; Radcliffe, Nathan M

2010-09-01

Parapapillary atrophy (PPA) progression has been associated with progressive glaucoma, but has proven to be difficult to assess clinically. We compared inter- and intra-observer agreement using a novel automated alternation flicker technology and side-by-side digital photography inspection for the evaluation of PPA progression. Consecutive patients with serial digital optic nerve photographs at least 1 year apart were included. Two graders (NR, BV) masked to image chronology assessed a set of photographs for progressive PPA using predefined criteria based on reference photographs containing mild, moderate, extensive or no PPA progression. At a separate session, the graders evaluated photographs using alternation flicker (EyeIC, Narberth, PA, USA) applying the same criteria. The order of patients and technique was randomized. Graders then assessed the same set of flickers and photographs a second time with the order of presentation reversed. The main outcome measure was the assessment of progressive PPA as identified by alternation flicker and digital photography inspection. Inter- and intra-observer agreement using each technique was assessed using the kappa statistic. A bootstrap method for comparing correlated kappa coefficients was used to assess statistical significance. Serial photographs from 131 eyes of 68 patients were evaluated. Both graders identified significantly more cases of PPA progression using flicker compared to photography (27-34% vs 8-13%; both pphotographs (kappa=0.52 vs 0.18, p=0.02). Intra-observer agreement was similar for both graders (photos: kappa=0.58 vs 0.57, p=0.97; flicker: kappa=0.61 vs 0.70, p=0.37). When progression was assessed by the number of progressive quadrants identified by each grader using a weighted kappa statistic, flicker inter-observer agreement was still moderate (kappa=0.45) and significantly better (p=0.01) than photography, which showed poor agreement (kappa=0.15). Intra-observer agreement with a weighted kappa for

Helping enhances productivity in campo flicker ( Colaptes campestris) cooperative groups

Science.gov (United States)

Dias, Raphael Igor; Webster, Michael S.; Macedo, Regina H.

2015-06-01

Reproductive adults in many bird species are assisted by non-breeding auxiliary helpers at the nest, yet the impact of auxiliaries on reproduction is variable and not always obvious. In this study, we tested Hamilton's rule and evaluated the effect of auxiliaries on productivity in the facultative cooperative breeder campo flicker ( Colaptes campestris campestris). Campo flickers have a variable mating system, with some groups having auxiliaries and others lacking them (i.e., unassisted pairs). Most auxiliaries are closely related to the breeding pair (primary auxiliaries), but some auxiliaries (secondary auxiliaries) are unrelated females that joined established groups. We found no effect of breeder quality (body condition) or territory quality (food availability) on group productivity, but the presence of auxiliaries increased the number of fledglings produced relative to unassisted pairs. Nonetheless, the indirect benefit of helping was small and did not outweigh the costs of delayed breeding and so seemed insufficient to explain the evolution of cooperative breeding in campo flickers. We concluded that some ecological constraints must limit dispersal or independent breeding, making staying in the group a "best-of-a-bad-job" situation for auxiliaries.

Investigation of Reactive Power Control Effects on Flicker and Harmonics Emission of a DFIG Wind Turbine

Directory of Open Access Journals (Sweden)

Amir Nagizadeh Ghoogdareh

2013-01-01

Full Text Available One of the most important power quality aspects in wind farms is voltage fluctuation or flicker which should be investigated due to the nature of wind speed variations. These variations result in power and voltage fluctuations at the load bus. Moreover, the wind generation systems may be assumed as a harmonics source because of their power electronic converters. There are numerous factors that affect flicker and harmonic emission of grid-connected wind turbines during continuous operation, such as wind characteristics (e.g. mean wind speed, turbulence intensity, type of generator and grid conditions (e.g. short circuit capacity, grid impedance angle. In this paper, an IEC based flickermeter is first modeled and then a variable speed wind turbine has been simulated by Matlab/Simulink software. The flicker and harmonics emissions of wind turbines equipped with DFIG during continuous operation and using output reactive control are investigated. The simulation results show that control of wind turbine output reactive power is an effective means for flicker mitigation during continuous operation. However, there should be a compromise between flicker reduction and harmonics level increase to enhance the whole power quality of wind turbine.

Mitigation of Flicker using STATCOM with Three-Level 12-pulse Voltage Source Inverter

OpenAIRE

Ali Z a'fari

2011-01-01

Voltage flicker is a disturbance in electrical power systems. The reason for this disturbance is mainly the large nonlinear loads such as electric arc furnaces. Synchronous static compensator (STATCOM) is considered as a proper technique to mitigate the voltage flicker. Application of more suitable and precise power electronic converter leads to a more precise performance of the compensator. In this paper a three-level 12-pulse voltage source inverter (VSI) with a 12-term...

EEG-based characterization of flicker perception

OpenAIRE

Lazo, M.; Tsoneva, T.; Garcia Molina, G.

2013-01-01

Steady-State Visual Evoked Potential (SSVEP) is an oscillatory electrical response appearing in the electroencephalogram (EEG) in response to flicker stimulation. The SSVEP manifests more prominently in electrodes located near the visual cortex and has oscillatory components at the stimulation frequency and/or harmonics. The phase and amplitude of the SSVEP are sensitive to stimulus parameters such as frequency, modu-lation depth, and spatial frequency. Research related to SSVEP and the human...

Review of Voltage Flicker Estimation Algorithms

OpenAIRE

Abhijith Augustine; Dr. T. Ruban Deva Prakash

2014-01-01

The quality of electric power is of supreme importance to electrical utilities and their customers. Modern equipments are more sensitive to power system anomalies than in the past. Microprocessor based controls and power electronics devices are sensitive to many types of disturbances. Minor power disruptions, which once would have been noticed only as a momentary flickering of the lights, may now completely interrupt whole automated factories because of sensitive electronic controllers or mak...

Improving the Mitigation of Voltage Flicker by Usage of Fuzzy Control in a Distribution Static Synchronous Compensator (DSTATCOM)

OpenAIRE

Saeed Abazari; Ebrahim Haghjou; Ghazanfar Shahgholiyan

2009-01-01

This paper presents a study about of a fuzzy Controlled STATCOM, which can be applied for mitigation of the voltage flicker in a distribution system. The voltage flicker is produced by a large variable load absorbing continuously changing currents such as an arc furnace. The DSTATCOM includes a voltage-sourced PWM inverter and its control system. The control strategy of the DSTATCOM plays an important role in maintaining the voltage flicker. Here, the DSTATCOM controller is designed with two...

Discovery of optical flickering from the symbiotic star EF Aquilae

Science.gov (United States)

Zamanov, R. K.; Boeva, S.; Nikolov, Y. M.; Petrov, B.; Bachev, R.; Latev, G. Y.; Popov, V. A.; Stoyanov, K. A.; Bode, M. F.; Martí, J.; Tomov, T.; Antonova, A.

2017-07-01

We report optical CCD photometry of the recently identified symbiotic star EF Aql. Our observations in Johnson V and B bands clearly show the presence of stochastic light variations with an amplitude of about 0.2 mag on a time scale of minutes. The observations point toward a white dwarf (WD) as the hot component in the system. It is the 11-th object among more than 200 symbiotic stars known with detected optical flickering. Estimates of the mass accretion rate onto the WD and the mass loss rate in the wind of the Mira secondary star lead to the conclusion that less than 1 per cent of the wind is captured by the WD. Eight further candidates for the detection of flickering in similar systems are suggested.

Flicker Mitigation by Speed Control of Permanent Magnet Synchronous Generator Variable-Speed Wind Turbines

OpenAIRE

Weihao Hu; Yunqian Zhang; Zhe Chen; Yanting Hu

2013-01-01

Grid-connected wind turbines are fluctuating power sources that may produce flicker during continuous operation. This paper presents a simulation model of a MW-level variable speed wind turbine with a full-scale back-to-back power converter and permanent magnet synchronous generator (PMSG) developed in the simulation tool of PSCAD/EMTDC. Flicker emission of this system is investigated. The 3p (three times per revolution) power oscillation due to wind shear and tower shadow effects is the sign...

Evaluation of cone function by a handheld non-mydriatic flicker electroretinogram device

Directory of Open Access Journals (Sweden)

Nakamura N

2016-06-01

Full Text Available Natsuko Nakamura,1 Kaoru Fujinami,1 Yoshinobu Mizuno,2 Toru Noda,2 Kazushige Tsunoda11Laboratory of Visual Physiology, Division of Vision Research, National Institute of Sensory Organs, 2Department of Ophthalmology, National Hospital Organization, National Tokyo Medical Center, Tokyo, JapanPurpose: Full-field electroretinograms (ERGs are used to evaluate retinal function in patients with various types of hereditary and acquired retinal diseases. However, ERG recordings require relatively invasive procedures, including pupillary dilation and the use of contact lens electrodes. Thus, it would be helpful to have a simpler and noninvasive screening method. The purpose of this study was to determine whether a new, handheld, portable ERG device, RETeval™, can be used to screen patients for cone dysfunction.Patients and methods: Thirty-five eyes of 35 patients who had reduced cone responses ascertained by a conventional ERG system using contact lens electrodes were studied. The causative diseases included achromatopsia, cone dystrophy, cone-rod dystrophy, retinitis pigmentosa, choroidal dystrophy, autoimmune retinopathy, and Stargardt disease. The flicker ERGs were recorded with the RETeval™ under undilated conditions with skin electrodes (stimulus strength, 3.0 cd·s/m2; frequency, 28.3 Hz, and the responses were compared to that of 50 healthy eyes. The amplitudes and implicit times of the fundamental component of the flicker ERGs were analyzed in three age groups: Group A, ≤20 years; Group B, 21–40 years; and Group C, ≥41 years.Results: In all of the age groups, the amplitudes of the ERGs were significantly smaller and the implicit times significantly longer in patients with cone dysfunction than in the control eyes. All but one of the patients had flicker amplitudes lower than the mean −2.0 standard deviation of control eyes.Conclusion: The RETeval™ has a potential of being used to screen for cone dysfunction. The entire examination

Visual stimuli for the P300 brain-computer interface: a comparison of white/gray and green/blue flicker matrices.

Science.gov (United States)

Takano, Kouji; Komatsu, Tomoaki; Hata, Naoki; Nakajima, Yasoichi; Kansaku, Kenji

2009-08-01

The white/gray flicker matrix has been used as a visual stimulus for the so-called P300 brain-computer interface (BCI), but the white/gray flash stimuli might induce discomfort. In this study, we investigated the effectiveness of green/blue flicker matrices as visual stimuli. Ten able-bodied, non-trained subjects performed Alphabet Spelling (Japanese Alphabet: Hiragana) using an 8 x 10 matrix with three types of intensification/rest flicker combinations (L, luminance; C, chromatic; LC, luminance and chromatic); both online and offline performances were evaluated. The accuracy rate under the online LC condition was 80.6%. Offline analysis showed that the LC condition was associated with significantly higher accuracy than was the L or C condition (Tukey-Kramer, p < 0.05). No significant difference was observed between L and C conditions. The LC condition, which used the green/blue flicker matrix was associated with better performances in the P300 BCI. The green/blue chromatic flicker matrix can be an efficient tool for practical BCI application.

Uniaxial flicker analysis of the psychophysical Stiles-Crawford effects

NARCIS (Netherlands)

Lochocki, Benjamin; Vohnsen, Brian

2017-01-01

Purpose: We report on a semi-automated system for frequency analysis of the Stiles-Crawford effect of the first kind (SCE-I) using flicker methodology designed to gain insight into the temporal dynamics of the perceived visibility for alternating pupil entrance points. We describe the system and its

Flickering light a history of neon

CERN Document Server

Ribbat, Christoph

2013-01-01

Without neon, Las Vegas might still be a sleepy desert town in Nevada and Times Square merely another busy intersection in New York City. Transformed by the installation of these brightly colored signs, these destinations are now world-famous, representing the vibrant heart of popular culture. But for some, neon lighting represents the worst of commercialism. Energized by the conflicting love and hatred people have for neon, Flickering Light explores its technological and intellectual history, from the discovery of the noble gas in late nineteenth-century London to its fading popul

Effect of the green/blue flicker matrix for P300-based brain–computer interface: an EEG–fMRI study.

Directory of Open Access Journals (Sweden)

Shiro eIkegami

2012-07-01

Full Text Available The visual P300 brain–computer interface (BCI, a popular system for EEG-based BCI, utilizes the P300 event-related potential to select an icon arranged in a flicker matrix. In the conventional P300 BCI speller paradigm, white/gray luminance intensification of each row/column in the matrix is used. In an earlier study, we applied green/blue luminance and chromatic change in the P300 BCI system and reported that this luminance and chromatic flicker matrix was associated with better performance and greater subject comfort compared with the conventional white/gray luminance flicker matrix. In this study, we used simultaneous EEG-fMRI recordings to identify brain areas that were more enhanced in the green/blue flicker matrix than in the white/gray flicker matrix, as these may highlight areas devoted to improved P300-BCI performance. The peak of the positive wave in the EEG data was detected under both conditions, and the peak amplitudes were larger at the parietal and occipital electrodes, particularly in the late components, under the green/blue condition than under the white/gray condition. fMRI data showed activation in the bilateral parietal and occipital cortices, and these areas, particularly those in the right hemisphere, were more activated under the green/blue condition than under the white/gray condition. The parietal and occipital regions more involved in the green/blue condition were part of the areas devoted to conventional P300s. These results suggest that the green/blue flicker matrix was useful for enhancing the so-called P300 responses.

Exploring the Performance Differences on the Flicker Task and the Conners' Continuous Performance Test in Adults with ADHD

Science.gov (United States)

Cohen, Andrew L.; Shapiro, Steven K.

2007-01-01

Objective: To examine the ability of the flicker task to demonstrate greater utility in discriminating performance in young adults with and without ADHD compared to the Conners' CPT (CCPT). Method: Flicker task and CCPT performance were compared between an ADHD (n = 28) and control (n = 30) group of college students. Results: This study replicated…

Elimination of image flicker in a fringe-field switching liquid crystal display by applying a bipolar voltage wave.

Science.gov (United States)

Oh, Seung-Won; Park, Jun-Hee; Lee, Ji-Hoon; Yoon, Tae-Hoon

2015-09-07

Recently, low-frequency driving of liquid crystal display (LCD) panels to minimize power consumption has drawn much attention. In the case in which an LCD panel is driven by a fringe-field at a low frequency, the image flickering phenomenon occurs when the sign of the applied electric field is reversed. We investigated image flickering induced by the flexoelectric effect in a fringe-field switching (FFS) liquid crystal cell in terms of the transmittance difference between frames and the ripple phenomenon. Experimental results show that image flicker due to transmittance difference can be eliminated completely and that the ripple phenomena can be reduced significantly by applying a bipolar voltage wave to the FFS cell.

A flickering study of nova-like systems KR Aur and UU Aqr

Science.gov (United States)

Dobrotka, A.; Mineshige, S.; Casares, J.

2012-03-01

We present a study of the flickering activity in two nova-like systems, KR Aur and UU Aqr. We applied a statistical model of flickering simulations in accretion discs based on turbulent angular momentum transport between two adjacent rings with an exponential distribution of the turbulence dimension scale. The model is based on a steady-state disc model, which is satisfied in the case of hot ionized discs of nova-like cataclysmic variables. Our model successfully fits the observed power-density spectrum of KR Aur with the disc parameter α= 0.10-0.40 and an inner-disc truncation radius in the range Rin= 0.88-1.67 × 109 cm. The exact values depend on the mass-transfer rate in the sense that α decreases and Rin increases with mass-transfer rate. In any case, the inner-disc radius found for KR Aur is considerably smaller than those for quiescent dwarf novae, as predicted by the disc instability model. On the other hand, our simulations fail to reproduce the power-density spectrum of UU Aqr. A tantalizing explanation involves the possible presence of spiral waves, which are expected in UU Aqr because of its low mass ratio but not in KR Aur. In general our model predicts the observed concentration of flickering in the central disc. We explain this by the radial dependence of the angular-momentum gradient.

Induction motor voltage flicker analysis and its mitigation measures using custom power devices: A case study

OpenAIRE

SANJAY. A. DEOKAR,; Dr. L. M. WAGHMARE

2010-01-01

This paper suggests methods for estimating short time flicker (PST) severity on 22/3.3 kV network supplying induction motor loads of municipal integrated water pumping system. The impact of additional connection of induction motors to the same system has been analyzed. Measurements are done at the point of common coupling (PCC) to identify background short time flicker levels and the contribution of the already operating induction motors. The paper also analyses and compares different voltage...

Investigation of Reactive Power Control Effects on Flicker and Harmonics Emission of a DFIG Wind Turbine

OpenAIRE

Amir Nagizadeh Ghoogdareh; Aref Doroudi; Mohammad Poormonfared Azimi

2013-01-01

One of the most important power quality aspects in wind farms is voltage fluctuation or flicker which should be investigated due to the nature of wind speed variations. These variations result in power and voltage fluctuations at the load bus. Moreover, the wind generation systems may be assumed as a harmonics source because of their power electronic converters. There are numerous factors that affect flicker and harmonic emission of grid-connected wind turbines during continuous operation, su...

Nest site attributes and temporal patterns of northern flicker nest loss: effects of predation and competition.

Science.gov (United States)

Fisher, Ryan J; Wiebe, Karen L

2006-04-01

To date, most studies of nest site selection have failed to take into account more than one source of nest loss (or have combined all sources in one analysis) when examining nest site characteristics, leaving us with an incomplete understanding of the potential trade-offs that individuals may face when selecting a nest site. Our objectives were to determine whether northern flickers (Colaptes auratus) may experience a trade-off in nest site selection in response to mammalian nest predation and nest loss to a cavity nest competitor (European starling, Sturnus vulgaris). We also document within-season temporal patterns of these two sources of nest loss with the hypothesis that flickers may also be constrained in the timing of reproduction under both predatory and competitive influence. Mammalian predators frequently depredated flicker nests that were: lower to the ground, less concealed by vegetation around the cavity entrance and at the base of the nest tree, closer to coniferous forest edges and in forest clumps with a high percentage of conifer content. Proximity to coniferous edges or coniferous trees increased the probability of nest predation, but nests near conifers were less likely to be lost to starlings. Flickers may thus face a trade-off in nest site selection with respect to safety from predators or competitors. Models suggested that peaks of nest predation and nest loss to eviction occurred at the same time, although a competing model suggested that the peak of nest loss to starlings occurred 5 days earlier than the peak of mammalian predation. Differences in peaks of mammalian predation and loss to starlings may constrain any adjustment in clutch initiation date by flickers to avoid one source of nest loss.

Flicker as a tool for characterizing planets though asterodensity profiling

DEFF Research Database (Denmark)

Kipping, D. M.; Bastien, F. A.; Stassun, K. G.

2014-01-01

Variability in the time series brightness of a star on a timescale of 8 hr, known as "flicker," has been previously demonstrated to serve as a proxy for the surface gravity of a star by Bastien et al. Although surface gravity is crucial for stellar classification, it is the mean stellar density t...

Quantitative retinal and choroidal blood flow during light, dark adaptation and flicker light stimulation in rats using fluorescent microspheres.

Science.gov (United States)

Shih, Yen-Yu I; Wang, Lin; De La Garza, Bryan H; Li, Guang; Cull, Grant; Kiel, Jeffery W; Duong, Timothy Q

2013-02-01

The present study aimed to quantify retinal and choroidal blood flow (BF) during light, dark adaptation and flicker light stimulation using the microsphere technique. Adult male Sprague-Dawley rats were anesthetized with isoflurane. Eyes were dark (Group I, n = 8), light (Group II, n = 8) adapted or stimulated with 10 Hz flicker light (Group III, n = 10). Retinal and choroidal BF were measured by a previously established method, using a mixture of 8 µm yellow-green and 10 µm red fluorescent microspheres. The microspheres were counted ex vivo in the dissected retina and choroid and in the reference arterial blood under a fluorescent microscope. The choroidal BF was 64.8 ± 29 µl/min (mean ± SD) during dark adaptation, not significantly different from that during light adaptation (66.0 ± 17.8 µl/min). The retinal BF was 13.5 ± 3.2 µl/min during 10 Hz flickering light stimulation, significantly higher than that during dark adaptation in the control fellow eyes (9.9 ± 2.9 µl/min). The choroidal BF values were not statistically different between flicker stimulation and dark adaptation. Retinal BF was 11.6 ± 2.9 µl/min during light adaptation. Dark adaptation did not increase retinal BF (Group I, 8.2 ± 2.4 µl/min; Group II, 9.9 ± 2.9 µl/min). These findings argue against a dark-induced or flicker-induced functional hyperemia in the choroid as a result of the demands of the outer retina. Retinal BF was not higher during dark adaptation. Our data support the conclusion that the inner retina has a higher energy demand in flicker conditions relative to dark.

A new frequency approach for light flicker evaluation in electric power systems

Science.gov (United States)

Feola, Luigi; Langella, Roberto; Testa, Alfredo

2015-12-01

In this paper, a new analytical estimator for light flicker in frequency domain, which is able to take into account also the frequency components neglected by the classical methods proposed in literature, is proposed. The analytical solutions proposed apply for any generic stationary signal affected by interharmonic distortion. The light flicker analytical estimator proposed is applied to numerous numerical case studies with the goal of showing i) the correctness and the improvements of the analytical approach proposed with respect to the other methods proposed in literature and ii) the accuracy of the results compared to those obtained by means of the classical International Electrotechnical Commission (IEC) flickermeter. The usefulness of the proposed analytical approach is that it can be included in signal processing tools for interharmonic penetration studies for the integration of renewable energy sources in future smart grids.

An SSVEP-actuated brain computer interface using phase-tagged flickering sequences: a cursor system.

Science.gov (United States)

Lee, Po-Lei; Sie, Jyun-Jie; Liu, Yu-Ju; Wu, Chi-Hsun; Lee, Ming-Huan; Shu, Chih-Hung; Li, Po-Hung; Sun, Chia-Wei; Shyu, Kuo-Kai

2010-07-01

This study presents a new steady-state visual evoked potential (SSVEP)-based brain computer interface (BCI). SSVEPs, induced by phase-tagged flashes in eight light emitting diodes (LEDs), were used to control four cursor movements (up, right, down, and left) and four button functions (on, off, right-, and left-clicks) on a screen menu. EEG signals were measured by one EEG electrode placed at Oz position, referring to the international EEG 10-20 system. Since SSVEPs are time-locked and phase-locked to the onsets of SSVEP flashes, EEG signals were bandpass-filtered and segmented into epochs, and then averaged across a number of epochs to sharpen the recorded SSVEPs. Phase lags between the measured SSVEPs and a reference SSVEP were measured, and targets were recognized based on these phase lags. The current design used eight LEDs to flicker at 31.25 Hz with 45 degrees phase margin between any two adjacent SSVEP flickers. The SSVEP responses were filtered within 29.25-33.25 Hz and then averaged over 60 epochs. Owing to the utilization of high-frequency flickers, the induced SSVEPs were away from low-frequency noises, 60 Hz electricity noise, and eye movement artifacts. As a consequence, we achieved a simple architecture that did not require eye movement monitoring or other artifact detection and removal. The high-frequency design also achieved a flicker fusion effect for better visualization. Seven subjects were recruited in this study to sequentially input a command sequence, consisting of a sequence of eight cursor functions, repeated three times. The accuracy and information transfer rate (mean +/- SD) over the seven subjects were 93.14 +/- 5.73% and 28.29 +/- 12.19 bits/min, respectively. The proposed system can provide a reliable channel for severely disabled patients to communicate with external environments.

Individual alpha peak frequency predicts 10 Hz flicker effects on selective attention

NARCIS (Netherlands)

Gulbinaite, Rasa; van Viegen, Tara; Wieling, Martijn; Cohen, Michael; vanRullen, Rufin

2017-01-01

Rhythmic visual stimulation (“flicker”) is primarily used to “tag” processing of low-level visual and high-level cognitive phenomena. However, preliminary evidence suggests that flicker may also entrain endogenous brain oscillations, thereby modulating cognitive processes supported by those brain

Dynamic properties of vision-II : theoretical relationships between flicker and flash thresholds

NARCIS (Netherlands)

Roufs, J.A.J.

1972-01-01

On the basis of some general system properties theoretical relationships have been established between parameters which characterise the sensitivity and inertia of the visual system in flicker and flash experiments. The results are in good agreement with the experimental relationships found in Part

Optimal Tuning of Multivariable Disturbance-Observer-Based Control for Flicker Mitigation Using Individual Pitch Control of Wind Turbine

DEFF Research Database (Denmark)

Raja, Muhammad Imran; Hussain, Dil muhammed Akbar; Soltani, Mohsen

2017-01-01

Multivariable disturbance accommodated observer based control (DOBC) scheme is presented to mitigate loads generated due to wind shear and tower shadow using individual blade pitch for above-rated wind speed condition of wind turbine. Wind shear and tower shadow add flickers as 1p, 3p, 6p and so on......, (p is the rotor rotational frequency) for three-bladed wind turbine. Novel DOBC with individual pitch control (IPC) to mitigate the flickers is presented and linear state-space model of wind turbine with tower dynamics is developed. The proposed controller is tuned using optimal control theory...... density of generator speed, drive-train torsion and tower fore-aft moment shows better mitigation to the flickers by proposed controller as compared with proportional–integral (PI) and disturbance accommodation control (DAC) with collective pitch control. Furthermore, it shows less degradation...

Linearized Model of Electrical Arc Furnace Suitable for Analysis of Flicker Mitigation

Czech Academy of Sciences Publication Activity Database

Valouch, Viktor

2003-01-01

Roč. 48, č. 2 (2003), s. 147-156 ISSN 0001-7043 R&D Projects: GA AV ČR IAA2057301 Institutional research plan: CEZ:AV0Z2057903 Keywords : flicker * electrical arc furnace * unified power quality conditioner Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

''Flicker'' in laser-plasma self-focusing

International Nuclear Information System (INIS)

Coggeshall, S.V.; Mead, W.C.; Jones, R.D.

1988-01-01

Under certain conditions, a new mode of laser-plasma self-focusing can occur which is characterized by a self-sustaining, continual shifting of filament-produced focal spots and a somewhat chaotic redistribution of light at the critical surface. Associated with this phenomenon is the possibility of significant intensity multiplication due to self-focusing. This flickering of laser light is caused by small amplitude, short wavelength ion acoustic waves which are produced near the foci of the filaments and subsequently propagate and convect toward the laser. As these ion fluctuations move toward the laser, they cause further light ray trajectory changes which shift the locations of the foci. New sound waves are launched and the process is self-perpetuated. 7 refs., 5 figs

HyperCube: A Small Lensless Position Sensing Device for the Tracking of Flickering Infrared LEDs.

Science.gov (United States)

Raharijaona, Thibaut; Mignon, Paul; Juston, Raphaël; Kerhuel, Lubin; Viollet, Stéphane

2015-07-08

An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs) with an accuracy much greater than the one dictated by the pixel pitch. With a size of only 1 cm3 and a mass of only 0.33 g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. Only three photosensors are placed on each side of the cubic configuration of the sensing device, making this sensor very inexpensive and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at a high frequency (>1 kHz) with a precision of 0.5°. The minimalistic design in terms of small size, low mass and low power consumption of this visual sensor makes it suitable for many applications in the field of the cooperative flight of unmanned aerial vehicles and, more generally, robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the flickering infrared markers.

HyperCube: A Small Lensless Position Sensing Device for the Tracking of Flickering Infrared LEDs

Directory of Open Access Journals (Sweden)

Thibaut Raharijaona

2015-07-01

Full Text Available An innovative insect-based visual sensor is designed to perform active marker tracking. Without any optics and a field-of-view of about 60°, a novel miniature visual sensor is able to locate flickering markers (LEDs with an accuracy much greater than the one dictated by the pixel pitch. With a size of only 1 cm3 and a mass of only 0.33 g, the lensless sensor, called HyperCube, is dedicated to 3D motion tracking and fits perfectly with the drastic constraints imposed by micro-aerial vehicles. Only three photosensors are placed on each side of the cubic configuration of the sensing device, making this sensor very inexpensive and light. HyperCube provides the azimuth and elevation of infrared LEDs flickering at a high frequency (>1 kHz with a precision of 0.5°. The minimalistic design in terms of small size, low mass and low power consumption of this visual sensor makes it suitable for many applications in the field of the cooperative flight of unmanned aerial vehicles and, more generally, robotic applications requiring active beacons. Experimental results show that HyperCube provides useful angular measurements that can be used to estimate the relative position between the sensor and the flickering infrared markers.

Utilizing Retinotopic Mapping for a Multi-Target SSVEP BCI With a Single Flicker Frequency.

Science.gov (United States)

Maye, Alexander; Zhang, Dan; Engel, Andreas K

2017-07-01

In brain-computer interfaces (BCIs) that use the steady-state visual evoked response (SSVEP), the user selects a control command by directing attention overtly or covertly to one out of several flicker stimuli. The different control channels are encoded in the frequency, phase, or time domain of the flicker signals. Here, we present a new type of SSVEP BCI, which uses only a single flicker stimulus and yet affords controlling multiple channels. The approach rests on the observation that the relative position between the stimulus and the foci of overt attention result in distinct topographies of the SSVEP response on the scalp. By classifying these topographies, the computer can determine at which position the user is gazing. Offline data analysis in a study on 12 healthy volunteers revealed that 9 targets can be recognized with about 95±3% accuracy, corresponding to an information transfer rate (ITR) of 40.8 ± 3.3 b/min on average. We explored how the classification accuracy is affected by the number of control channels, the trial length, and the number of EEG channels. Our findings suggest that the EEG data from five channels over parieto-occipital brain areas are sufficient for reliably classifying the topographies and that there is a large potential to improve the ITR by optimizing the trial length. The robust performance and the simple stimulation setup suggest that this approach is a prime candidate for applications on desktop and tablet computers.

The reliability and internal consistency of one-shot and flicker change detection for measuring individual differences in visual working memory capacity.

Science.gov (United States)

Pailian, Hrag; Halberda, Justin

2015-04-01

We investigated the psychometric properties of the one-shot change detection task for estimating visual working memory (VWM) storage capacity-and also introduced and tested an alternative flicker change detection task for estimating these limits. In three experiments, we found that the one-shot whole-display task returns estimates of VWM storage capacity (K) that are unreliable across set sizes-suggesting that the whole-display task is measuring different things at different set sizes. In two additional experiments, we found that the one-shot single-probe variant shows improvements in the reliability and consistency of K estimates. In another additional experiment, we found that a one-shot whole-display-with-click task (requiring target localization) also showed improvements in reliability and consistency. The latter results suggest that the one-shot task can return reliable and consistent estimates of VWM storage capacity (K), and they highlight the possibility that the requirement to localize the changed target is what engenders this enhancement. Through a final series of four experiments, we introduced and tested an alternative flicker change detection method that also requires the observer to localize the changing target and that generates, from response times, an estimate of VWM storage capacity (K). We found that estimates of K from the flicker task correlated with estimates from the traditional one-shot task and also had high reliability and consistency. We highlight the flicker method's ability to estimate executive functions as well as VWM storage capacity, and discuss the potential for measuring multiple abilities with the one-shot and flicker tasks.

Correlation between MEG and BOLD fMRI signals induced by visual flicker stimuli

Institute of Scientific and Technical Information of China (English)

Chu Renxin; Holroyd Tom; Duyn Jeff

2007-01-01

The goal of this work was to investigate how the MEG signal amplitude correlates with that of BOLD fMRI.To investigate the correlation between fMRI and macroscopic electrical activity, BOLD fMRI and MEG was performed on the same subjects (n =5). A visual flicker stimulus of varying temporal frequency was used to elicit neural responses in early visual areas. A strong similarity was observed in frequency tuning curves between both modalities.Although, averaged over subjects, the BOLD tuning curve was somewhat broader than MEG, both BOLD and MEG had maxima at a flicker frequency of 10 Hz. Also, we measured the first and second harmonic components as the stimuli frequency by MEG. In the low stimuli frequency (less than 6 Hz), the second harmonic has comparable amplitude with the first harmonic, which implies that neural frequency response is nonlinear and has more nonlinear components in low frequency than in high frequency.

A flicker noise/IM3 cancellation technique for active mixer using negative impedance

NARCIS (Netherlands)

Cheng, W.; Annema, Anne J.; Wienk, Gerhardus J.M.; Nauta, Bram

2013-01-01

Abstract—This paper presents an approach to simultaneously cancel flicker noise and IM3 in Gilbert-type mixers, utilizing negative impedances. For proof of concept, two prototype double-balanced mixers in 0.16- m CMOS are fabricated. The first demonstration mixer chip was optimized for full IM3

[Sensitivity and specificity of flicker perimetry with Pulsar. Comparison with achromatic (white-on-white) perimetry in glaucoma patients].

Science.gov (United States)

Göbel, K; Erb, C

2013-02-01

The early detection of functional glaucoma damage plays an increasingly more central role in the diagnosis and treatment of glaucoma disease. Using selective perimetry detection of early glaucomatous defects is more likely and one of these methods is flicker perimetry with Pulsar. Flicker perimetry is used to analyze the temporal visual function in combination with spatial resolution and contrast sensitivity as opposed to standard automated perimetry which measures the differential light sensitivity with a non-specific stimulus. This study showed a higher sensitivity and specificity of Pulsar perimetry in comparison to achromatic perimetry in glaucoma patients.

Flicker sensitivity as a function of target area with and without temporal noise.

Science.gov (United States)

Rovamo, J; Donner, K; Näsänen, R; Raninen, A

2000-01-01

Flicker sensitivities (1-30 Hz) in foveal, photopic vision were measured as functions of stimulus area with and without strong external white temporal noise. Stimuli were circular, sinusoidally flickering sharp-edged spots of variable diameters (0.25-4 degrees ) but constant duration (2 s), surrounded by a uniform equiluminant field. The data was described with a model comprising (i) low-pass filtering in the retina (R), with a modulation transfer function (MTF) of a form derived from responses of cones; (ii) normalisation of the temporal luminance distribution by the average luminance; (iii) high-pass filtering by postreceptoral neural pathways (P), with an MTF proportional to temporal frequency; (iv) addition of internal white neural noise (N(i)); (v) integration over a spatial window; and (vi) detection by a suboptimal temporal matched filter of efficiency eta. In strong external noise, flicker sensitivity was independent of spot area. Without external noise, sensitivity increased with the square root of stimulus area (Piper's law) up to a critical area (A(c)), where it reaches a maximum level (S(max)). Both A(c) and eta were monotonic functions of temporal frequency (f), such that log A(c) increased and log eta decreased linearly with log f. Remarkably, the increase in spatial integration area and the decrease in efficiency were just balanced, so A(c)(f)eta(f) was invariant against f. Thus the bandpass characteristics of S(max)(f) directly reflected the composite effect of the distal filters R(f) and P(f). The temporal equivalent (N(it)) of internal neural noise (N(i)) decreased in inverse proportion to spot area up to A(c) and then stayed constant indicating that spatially homogeneous signals and noise are integrated over the same area.

Effects of Constant Flickering Light on Refractive Status, 5-HT and 5-HT2A Receptor in Guinea Pigs.

Science.gov (United States)

Li, Bing; Luo, Xiumei; Li, Tao; Zheng, Changyue; Ji, Shunmei; Ma, Yuanyuan; Zhang, Shuangshuang; Zhou, Xiaodong

2016-01-01

To investigate the effects of constant flickering light on refractive development, the role of serotonin (i.e.5-hydroxytryptamine, 5-HT)and 5-HT2A receptor in myopia induced by flickering light in guinea pigs. Forty-five guinea pigs were randomly divided into three groups: control, form deprivation myopia (FDM) and flickering light induced myopia (FLM) groups(n = 15 for each group). The right eyes of the FDM group were covered with semitransparent hemispherical plastic shells serving as eye diffusers. Guinea pigs in FLM group were raised with illumination of a duty cycle of 50% at a flash frequency of 0.5Hz. The refractive status, axial length (AL), corneal radius of curvature(CRC) were measured by streak retinoscope, A-scan ultrasonography and keratometer, respectively. Ultramicroscopy images were taken by electron microscopy. The concentrations of 5-HTin the retina, vitreous body and retinal pigment epithelium (RPE) were assessed by high performance liquid chromatography, the retinal 5-HT2A receptor expression was evaluated by immunohistofluorescence and western blot. The refraction of FDM and FLM eyes became myopic from some time point (the 4th week and the 6th week, respectively) in the course of the experiment, which was indicated by significantly decreased refraction and longer AL when compared with the controls (plight could cause progressive myopia in guinea pigs. 5-HT and 5-HT2A receptor increased both in form deprivation myopia and flickering light induced myopia, indicating that 5-HT possibly involved in myopic development via binding to5-HT2A receptor.

Stochastic dynamics: Crossover from 1/f3 to flicker noise

International Nuclear Information System (INIS)

Canessa, E.; Nguyen, V.L.

1993-01-01

Finite time processes within the limits of the Newton equation and zero inertia motion (i.e., road to chaos) are studied by numerically solving the ordinary, stochastic Langevin equation in 1D for a free particle with inertial moving in a medium with viscosity γ. In this simulations, the scaling behaviour of particle trajectories χ(t) and velocities v(t) with time are derived and the inclusion of non-zero particle masses is shown to define the asymptotic time limit τ c at which - independently of γ - the system evolves into the well-known statistically stationary state characterized by 2 (t) > is proportional to t and flicker noise. The time τ c is further analysed from the correlation length given by the 2-point autocorrelation function of the particle velocity at each value of γ. It is found that the noise power spectrum of v(t) is characterized by flicker noise for frequencies f ≤ f c ∼ 1/τ c , whereas for f > f c , the noise power spectra behave as 1/f υ , where υ varies between the limits of Newton's equation (i.e., υ = 3) and road to chaos (i.e., υ = 1). Furthermore, at times τ c and 0 f (γ) while the single particle trajectories are shown to display a rather different subset of exponents on increasing γ. Generic features of this transition are nicely given by Poincare maps in the velocity space. (author). 23 refs, 8 figs

Fast entrainment of human electroencephalogram to a theta-band photic flicker during successful memory encoding

Directory of Open Access Journals (Sweden)

Naoyuki eSato

2013-05-01

Full Text Available Theta band power (4-8Hz in the scalp electroencephalogram (EEG is thought to be stronger during memory encoding for subsequently remembered items than for forgotten items. According to simultaneous EEG-functional magnetic resonance imaging (fMRI measurements, the memory-dependent EEG theta is associated with multiple regions of the brain. This suggests that the multiple regions cooperate with EEG theta synchronization during successful memory encoding. However, a question still remains: What kind of neural dynamic organizes such a memory-dependent global network? In this study, the modulation of the EEG theta entrainment property during successful encoding was hypothesized to lead to EEG theta synchronization among a distributed network. Then, a transient response of EEG theta to a theta-band photic flicker with a short duration was evaluated during memory encoding. In the results, flicker-induced EEG power increased and decreased with a time constant of several hundred milliseconds following the onset and the offset of the flicker, respectively. Importantly, the offset response of EEG power was found to be significantly decreased during successful encoding. Moreover, the offset response of the phase locking index was also found to associate with memory performance. According to computational simulations, the results are interpreted as a smaller time constant (i.e., faster response of a driven harmonic oscillator rather than a change in the spontaneous oscillatory input. This suggests that the fast response of EEG theta forms a global EEG theta network among memory-related regions during successful encoding, and it contributes to a flexible formation of the network along the time course.

Fast entrainment of human electroencephalogram to a theta-band photic flicker during successful memory encoding.

Science.gov (United States)

Sato, Naoyuki

2013-01-01

Theta band power (4-8 Hz) in the scalp electroencephalogram (EEG) is thought to be stronger during memory encoding for subsequently remembered items than for forgotten items. According to simultaneous EEG-functional magnetic resonance imaging (fMRI) measurements, the memory-dependent EEG theta is associated with multiple regions of the brain. This suggests that the multiple regions cooperate with EEG theta synchronization during successful memory encoding. However, a question still remains: What kind of neural dynamic organizes such a memory-dependent global network? In this study, the modulation of the EEG theta entrainment property during successful encoding was hypothesized to lead to EEG theta synchronization among a distributed network. Then, a transient response of EEG theta to a theta-band photic flicker with a short duration was evaluated during memory encoding. In the results, flicker-induced EEG power increased and decreased with a time constant of several hundred milliseconds following the onset and the offset of the flicker, respectively. Importantly, the offset response of EEG power was found to be significantly decreased during successful encoding. Moreover, the offset response of the phase locking index was also found to associate with memory performance. According to computational simulations, the results are interpreted as a smaller time constant (i.e., faster response) of a driven harmonic oscillator rather than a change in the spontaneous oscillatory input. This suggests that the fast response of EEG theta forms a global EEG theta network among memory-related regions during successful encoding, and it contributes to a flexible formation of the network along the time course.

Application of a single-flicker online SSVEP BCI for spatial navigation.

Science.gov (United States)

Chen, Jingjing; Zhang, Dan; Engel, Andreas K; Gong, Qin; Maye, Alexander

2017-01-01

A promising approach for brain-computer interfaces (BCIs) employs the steady-state visual evoked potential (SSVEP) for extracting control information. Main advantages of these SSVEP BCIs are a simple and low-cost setup, little effort to adjust the system parameters to the user and comparatively high information transfer rates (ITR). However, traditional frequency-coded SSVEP BCIs require the user to gaze directly at the selected flicker stimulus, which is liable to cause fatigue or even photic epileptic seizures. The spatially coded SSVEP BCI we present in this article addresses this issue. It uses a single flicker stimulus that appears always in the extrafoveal field of view, yet it allows the user to control four control channels. We demonstrate the embedding of this novel SSVEP stimulation paradigm in the user interface of an online BCI for navigating a 2-dimensional computer game. Offline analysis of the training data reveals an average classification accuracy of 96.9±1.64%, corresponding to an information transfer rate of 30.1±1.8 bits/min. In online mode, the average classification accuracy reached 87.9±11.4%, which resulted in an ITR of 23.8±6.75 bits/min. We did not observe a strong relation between a subject's offline and online performance. Analysis of the online performance over time shows that users can reliably control the new BCI paradigm with stable performance over at least 30 minutes of continuous operation.

[A new hypothesis for the treatment of amblyopia: the flicker stimulator].

Science.gov (United States)

Parrozzani, A; Fedriga, P; Ferrari, E; De Vincentiis, L

1984-01-01

A variety of cells are involved in the pathogenesis of amblyopia : ON, OFF, ON-OFF cells, postsynaptic cells, neurons of striate cortex and the select interest of the macula. The need for stimulation of these cells in treating amblyopia forms the theoretical basis of the Flicker stimulator with red monochromatic light (LED, 655 nm). The authors present a clinical investigation on 35 subjects with anisometropic or strabismic amblyopia, before extensive treatment with classic anti-amblyopic techniques without satisfactory improvement obtaining significant statistical results (p less than 0,001).

Sharpening vision by adapting to flicker

Science.gov (United States)

Arnold, Derek H.; Williams, Jeremy D.; Phipps, Natasha E.; Goodale, Melvyn A.

2016-01-01

Human vision is surprisingly malleable. A static stimulus can seem to move after prolonged exposure to movement (the motion aftereffect), and exposure to tilted lines can make vertical lines seem oppositely tilted (the tilt aftereffect). The paradigm used to induce such distortions (adaptation) can provide powerful insights into the computations underlying human visual experience. Previously spatial form and stimulus dynamics were thought to be encoded independently, but here we show that adaptation to stimulus dynamics can sharpen form perception. We find that fast flicker adaptation (FFAd) shifts the tuning of face perception to higher spatial frequencies, enhances the acuity of spatial vision—allowing people to localize inputs with greater precision and to read finer scaled text, and it selectively reduces sensitivity to coarse-scale form signals. These findings are consistent with two interrelated influences: FFAd reduces the responsiveness of magnocellular neurons (which are important for encoding dynamics, but can have poor spatial resolution), and magnocellular responses contribute coarse spatial scale information when the visual system synthesizes form signals. Consequently, when magnocellular responses are mitigated via FFAd, human form perception is transiently sharpened because “blur” signals are mitigated. PMID:27791115

Cone function studied with flicker electroretinogram during progressive retinal degeneration in RCS rats.

Science.gov (United States)

Pinilla, I; Lund, R D; Sauvé, Y

2005-01-01

The Royal College of Surgeons (RCS) rat has a primary defect in retinal pigment epithelial cells that leads to the progressive loss of photoreceptors and central visual responsiveness. While most rods are lost by 90 days of age (P90), cones degenerate more slowly, and can be detected anatomically up to 2 years of age, despite massive neuronal death and retinal remodelling. To examine how this progressive degenerative process impacts on cone function, we recorded the electroretingram to white light flashes (1.37 log cd s m(-2)) presented at frequencies ranging from 3 to 50 Hz, under light adapted conditions (29.8 cd m(-2)). Pigmented dystrophic and congenic non-dystrophic RCS rats aged from 18 to 300 days were studied. In all responsive animals at all ages, maximal amplitudes were obtained at 3 Hz. In both non-dystrophic and dystrophic rats, there was an increase from P18 to P21 in response amplitude and critical fusion frequency. After P21, these two parameters declined progressively with age in dystrophic rats. Other changes included prolongation in latency, which was first detected prior to the initiation of amplitude reduction. While phase shifts were also detected in dystrophic RCS rats, they appeared at later degenerative stages. The latest age at which responses could be elicited in dystrophic rats was at P200, with positive waves being replaced by negative deflections. The effect of increments in the intensity of background illumination was tested at P50 in both groups. This caused a diminution in flicker response amplitude and critical fusion frequencies in non-dystrophics, while in dystrophic animals, response amplitudes were reduced only at low frequencies and critical fusion frequencies were unaltered. In conclusion, although dystrophic RCS rats undergo a progressive decline in cone function with age, the flicker responsiveness at P21 is comparable to that of non-dystrophic congenic rats, suggesting normal developmental maturation of the cone system in

CALiPER Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps

Energy Technology Data Exchange (ETDEWEB)

none,

2014-12-31

This CALiPER report examines the characteristics of a subset of lamps from CALiPER Retail Lamps Study 3 in more detail. Specifically, it focuses on the dimming, power quality, and flicker characteristics of 14 LED A lamps, as controlled by four different retail-available dimmers.

The Impact of the Shallow-Trench Isolation Effect on Flicker Noise of Source Follower MOSFETs in a CMOS Image Sensor.

Science.gov (United States)

Fan, C C; Chiu, Y C; Liu, C; Lai, W W; Cheng, C H; Lin, D L; Li, G R; Lo, Y H; Chang, C W; Tsai, C C; Chang, C Y

2018-06-01

The flicker noise of source follower transistors is the dominant noise source in image sensors. This paper reports a systematic study of the shallow trench isolation effect in transistors with different sizes under high temperature conditions that correspond to the quantity of empty defect sites. The effects of shallow trench isolation sidewall defects on flicker noise characteristics are investigated. In addition, the low-frequency noise and subthreshold swing degrade simultaneously in accordance to the device gate width scaling. Both serious subthreshold leakage and considerable noise can be attributed to the high trap density near the STI edge. Consequently, we propose a coincidental relationship between the noise level and the subthreshold characteristic; its trend is identical to the experiments and simulation results.

CALiPER Report 20.2: Dimming, Flicker, and Power Quality Characteristics of LED PAR38 Lamps

Energy Technology Data Exchange (ETDEWEB)

None, None

2014-03-31

This report focuses on the flicker and power quality performance of the Series 20 lamps at full output and various dimmed levels. All of the Series 20 PAR38 lamps that manufacturers claimed to be dimmable (including all halogen lamps) were evaluated individually (one lamp at a time) both on a switch and under the control of a phase-cut dimmer designed for use with "all classes of bulbs." Measurements of luminous flux, flicker, and power quality were taken at 10 target dimmed settings and compared with operation on a switch. Because only a single unit of each product was evaluated on a single dimmer that may or may not have been recommended by its manufacturer, this report focuses on the performance of the products relative to each other, rather than the best-case performance of each lamp or variation in performance delivered from each lamp. Despite these limitations, the results suggest that LED performance is improving, and performance trends are beginning to emerge, perhaps due in part to the identification of preferred LED driver strategies for lamp products.

Retail Lamps Study 3.1: Dimming, Flicker, and Power Quality Characteristics of LED A Lamps

Energy Technology Data Exchange (ETDEWEB)

Royer, Michael P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Poplawski, Michael E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Brown, Charles C. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2014-12-01

To date, all three reports in the retail lamps series have focused on basic performance parameters, such as lumen output, efficacy, and color quality. This report goes a step further, examining the photoelectric characteristics (i.e., dimming and flicker) of a subset of lamps from CALiPER Retails Lamps Study 3. Specifically, this report focuses on the dimming, power quality, and flicker characteristics of 14 LED A lamps, as controlled by four different retail-available dimmers. The results demonstrate notable variation across the various lamps, but little variation between the four dimmers. Overall, the LED lamps: ~tended to have higher relative light output compared to the incandescent and halogen benchmark at the same dimmer output signal (RMS voltage). The lamps’ dimming curves (i.e., the relationship between control signal and relative light output) ranged from linear to very similar to the square-law curve typical of an incandescent lamp. ~generally exhibited symmetrical behavior—the same dimming curve—when measured proceeding from maximum to minimum or minimum to maximum control signal. ~mostly dimmed below 10% of full light output, with some exceptions for specific lamp and dimmer combinations ~exhibited a range of flicker characteristics, with many comparing favorably to the level typical of a magnetically-ballasted fluorescent lamp through at least a majority of the dimming range. ~ always exceeded the relative (normalized) efficacy over the dimming range of the benchmark lamps, which rapidly decline in efficacy when they are dimmed. This report generally does not attempt to rank the performance of one product compared to another, but instead focuses on the collective performance of the group versus conventional incandescent or halogen lamps, the performance of which is likely to be the baseline for a majority of consumers. Undoubtedly, some LED lamps perform better—or more similar to conventional lamps—than others. Some perform desirably for one

Self-organized complex space charge configurations at the origin of flicker noise

International Nuclear Information System (INIS)

Popescu, S.; Lozneanu, E.; Sanduloviciu, M.

2003-01-01

Based on experimental results obtained from a plasma diode we explain the fluctuations of the voltage supported by a non-linear gaseous conductor by the dynamical behavior of spatiotemporal patterns, in the form of moving double layers, formed after self-organization. Such phenomena appear when the system is subjected to an external constraint that creates and maintains a local gradient of electron kinetic energy. The described phenomenology suggests a plausible explanation for the appearance of flicker noise also in other physical systems, as for example semiconductors and, implicitly, offers a new model for the so-called self-organized criticality concept

Flickering of the symbiotic variable CH Cygni during outburst

Energy Technology Data Exchange (ETDEWEB)

Slovak, M H [Texas Univ., Austin (USA). Dept. of Astronomy; Africano, J

1978-11-01

High-speed and conventional BVRI photometry are reported for the bright symbiotic variable CH Cygni (M6 IIIe), obtained during the course of a recent outburst. Unlike the quiescent symbiotic stars, the presence of flickering similar in nature to that seen in the cataclysmic variables has been confirmed during this active phase. The BVRI photometry for a sample of stars in the field is used to derive the reddening and the distance to CH Cyg. A composite energy distribution is derived from 0.35 to 11.0 ..mu..m which clearly establishes the existence of a variable, blue continuum. The lack of variability in the near infrared suggests that the blue continuum arises from a hot companion. A binary model including a subluminous hot companion accreting material from the stellar wind of an SRa variable is discussed to account for the observed photometric properties.

Wind turbines, flicker, and photosensitive epilepsy: characterizing the flashing that may precipitate seizures and optimizing guidelines to prevent them.

Science.gov (United States)

Harding, Graham; Harding, Pamela; Wilkins, Arnold

2008-06-01

Wind turbines are known to produce shadow flicker by interruption of sunlight by the turbine blades. Known parameters of the seizure provoking effect of flicker, i.e., contrast, frequency, mark-space ratio, retinal area stimulated and percentage of visual cortex involved were applied to wind turbine features. The proportion of patients affected by viewing wind turbines expressed as distance in multiples of the hub height of the turbine showed that seizure risk does not decrease significantly until the distance exceeds 100 times the hub height. Since risk does not diminish with viewing distance, flash frequency is therefore the critical factor and should be kept to a maximum of three per second, i.e., sixty revolutions per minute for a three-bladed turbine. On wind farms the shadows cast by one turbine on another should not be viewable by the public if the cumulative flash rate exceeds three per second. Turbine blades should not be reflective.

Statistical Analysis of Bending Rigidity Coefficient Determined Using Fluorescence-Based Flicker-Noise Spectroscopy.

Science.gov (United States)

Doskocz, Joanna; Drabik, Dominik; Chodaczek, Grzegorz; Przybyło, Magdalena; Langner, Marek

2018-06-01

Bending rigidity coefficient describes propensity of a lipid bilayer to deform. In order to measure the parameter experimentally using flickering noise spectroscopy, the microscopic imaging is required, which necessitates the application of giant unilamellar vesicles (GUV) lipid bilayer model. The major difficulty associated with the application of the model is the statistical character of GUV population with respect to their size and the homogeneity of lipid bilayer composition, if a mixture of lipids is used. In the paper, the bending rigidity coefficient was measured using the fluorescence-enhanced flicker-noise spectroscopy. In the paper, the bending rigidity coefficient was determined for large populations of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1,2-dioleoyl-sn-glycero-3-phosphocholine vesicles. The quantity of obtained experimental data allows to perform statistical analysis aiming at the identification of the distribution, which is the most appropriate for the calculation of the value of the membrane bending rigidity coefficient. It has been demonstrated that the bending rigidity coefficient is characterized by an asymmetrical distribution, which is well approximated with the gamma distribution. Since there are no biophysical reasons for that we propose to use the difference between normal and gamma fits as a measure of the homogeneity of vesicle population. In addition, the effect of a fluorescent label and types of instrumental setups on determined values has been tested. Obtained results show that the value of the bending rigidity coefficient does not depend on the type of a fluorescent label nor on the type of microscope used.

Estimating annoyance to calculated wind turbine shadow flicker is improved when variables associated with wind turbine noise exposure are considered.

Science.gov (United States)

Voicescu, Sonia A; Michaud, David S; Feder, Katya; Marro, Leonora; Than, John; Guay, Mireille; Denning, Allison; Bower, Tara; van den Berg, Frits; Broner, Norm; Lavigne, Eric

2016-03-01

The Community Noise and Health Study conducted by Health Canada included randomly selected participants aged 18-79 yrs (606 males, 632 females, response rate 78.9%), living between 0.25 and 11.22 km from operational wind turbines. Annoyance to wind turbine noise (WTN) and other features, including shadow flicker (SF) was assessed. The current analysis reports on the degree to which estimating high annoyance to wind turbine shadow flicker (HAWTSF) was improved when variables known to be related to WTN exposure were also considered. As SF exposure increased [calculated as maximum minutes per day (SFm)], HAWTSF increased from 3.8% at 0 ≤ SFm wind turbine-related features, concern for physical safety, and noise sensitivity. Reported dizziness was also retained in the final model at p = 0.0581. Study findings add to the growing science base in this area and may be helpful in identifying factors associated with community reactions to SF exposure from wind turbines.

Quenching of light flickering in synthetic guanine crystals in aqueous solutions under strong static magnetic fields

Science.gov (United States)

Mootha, A.; Takanezawa, Y.; Iwasaka, M.

2018-05-01

The present study focused on the vibration of micro crystal particles of guanine due to Brownian motion. The organic particle has a refractive index of 1.83 and caused a flickering of light. To test the possibility of using magnetic properties under wet conditions, changes in the frequency of particle vibration by applying magnetic fields were investigated. At first, we found that the exposure at 5 T inhibited the flickering light intensities and the particle vibration slightly decreased. Next, we carried out a high speed camera measurement of the Brownian motion of the particle with a time resolution of 100 flame per second (fps) with and without magnetic field exposures. It was revealed that the vibrational speed of synthetic particles was enhanced at 500 mT. Detailed analyses of the particle vibration by changing the direction of magnetic fields versus the light source revealed that the Brownian motion's vibrational frequency was entrained under magnetic fields at 500 mT, and an increase in vibration speed to 20Hz was observed. Additional measurements of light scattering fluctuation using photo-detector and analyses on auto-correlation also confirmed this speculation. The studied Brownian vibration may be influenced by the change in mechanical interactions between the vibration particles and surrounding medium. The discovered phenomena can be applied for molecular and biological interactions in future studies.

Higher glucose level and systemic oxidative stress decrease the mean velocity index of the retinal artery during flickering light stimulation in type 1 diabetes.

Science.gov (United States)

Debelić, Vladimir; Drnovšek Olup, Brigita; Žižek, Bogomir; Skitek, Milan; Jerin, Aleš

2016-10-31

To determine whether higher glucose level and systemic oxidative stress decrease mean velocity (MV) index of the central retinal artery (CRA) during flickering light stimulation in type 1 diabetes (T1D). The study was performed in the period from 2008 to 2015 at the University Eye Clinic in Ljubljana. 41 patients with T1D and 37 participants without diabetes were included. MV in the CRA was measured using Doppler ultrasound diagnostics in basal conditions and during 8 Hz flickering light irritation. The plasma levels of glucose, fructosamine, 8-hydroxy-2'-deoxyguanosine (8-OHdG), triglycerides, cholesterol, and low-density lipoprotein (LDL) were measured. Patients with T1D had significantly higher levels of blood glucose (Ptriglycerides (P=0.108), cholesterol (P=0.531), and LDL (P=0.645) between the groups. Patients with T1D also had a significantly lower MV index in the CRA (1.11±0.15 vs 1.24±0.23; P=0.010). In the T1D group, a significant negative correlation was found between the level of glucose (r=0.58; Pindex in the CRA. At the same time, in this group fructosamine and 8-OHdG levels had a separate effect on the MV index (adjusted R2=0.38, Pglucose levels, the medium-term glucose level, and systemic oxidative stress could importantly reduce retinal vasodilatation during flickering light irritation in patients with T1D.

Flicker noise comparison of direct conversion mixers using Schottky and HBT dioderings in SiGe:C BiCMOS technology

DEFF Research Database (Denmark)

Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld

2015-01-01

In this paper, we present flicker noise measurements of two X-band direct conversion mixers implemented in a SiGe:C BiCMOS technology. Both mixers use a ring structure with either Schottky diodes or diode-connected HBTs for double balanced operation. The mixers are packaged in a metal casing on a...... circuit demonstrates a 1/f noise corner frequency around 10 kHz....

Robust spatial memory maps in flickering neuronal networks: a topological model

Science.gov (United States)

Dabaghian, Yuri; Babichev, Andrey; Memoli, Facundo; Chowdhury, Samir; Rice University Collaboration; Ohio State University Collaboration

It is widely accepted that the hippocampal place cells provide a substrate of the neuronal representation of the environment--the ``cognitive map''. However, hippocampal network, as any other network in the brain is transient: thousands of hippocampal neurons die every day and the connections formed by these cells constantly change due to various forms of synaptic plasticity. What then explains the remarkable reliability of our spatial memories? We propose a computational approach to answering this question based on a couple of insights. First, we propose that the hippocampal cognitive map is fundamentally topological, and hence it is amenable to analysis by topological methods. We then apply several novel methods from homology theory, to understand how dynamic connections between cells influences the speed and reliability of spatial learning. We simulate the rat's exploratory movements through different environments and study how topological invariants of these environments arise in a network of simulated neurons with ``flickering'' connectivity. We find that despite transient connectivity the network of place cells produces a stable representation of the topology of the environment.

Meteoroid rotation and fireball flickering: a case study of the Innisfree fireball

Science.gov (United States)

Beech, Martin

2001-09-01

Some 5 per cent of bright meteors show rapid, quasi-periodic brightness variations. It is argued that this effect, observationally known as flickering, is a manifestation of the rotational modulation of surface mass loss through ablation of a non-spherical meteoroid. We develop a set of time-dependent, single-body ablation equations that include the effect of cross-section area modulation. We present a discussion of the effects that the rotation of a non-spherical meteoroid has on the resultant meteor light curve, and we look in depth at the data related to the fireball associated with the fall of the Innisfree meteorite. We find that the parent object to the Innisfree meteorite was spinning at a rotation frequency of 2.5Hz when it encountered the Earth's upper atmosphere. We also find that the Innisfree parent body had an initial mass of about 20kg and that the ratio of its semiminor and semimajor axes was about 0.5.

Flicker-defined form perimetry in glaucoma patients.

Science.gov (United States)

Horn, Folkert K; Kremers, Jan; Mardin, Christian Y; Jünemann, Anselm G; Adler, Werner; Tornow, Ralf P

2015-03-01

To assess the potential of flicker-defined form (FDF) perimetry to detect functional loss in patient groups with beginning glaucoma, and to evaluate the dynamic range of the FDF stimulus in individual patients and at individual test positions. FDF perimetry and standard automated perimetry (SAP) were performed at identical test locations (adapted G1 protocol) in 60 healthy subjects and 111 glaucoma patients. All patients showed glaucomatous optic disc appearance. Grouping within the glaucoma cohort was based on SAP-performance: 33 "preperimetric" open-angle glaucoma (OAG) patients, 28 "borderline" OAG (focal defects and SAP-mean defect (MD) <2 dB), 33 "early" OAG (SAP-MD < 5 dB), 17 "advanced" OAG. All participants were experienced in psychophysical and perimetric tests. Defect values and the areas under receiver operating characteristic curves (ROC) in patient groups were statistically compared. The values of FDF-MD in the preperimetric, borderline, and early OAG group were 2.7 ± 3.4 dB, 5.5 ± 2.6 dB, and 8.5 ± 3.4 dB respectively (all significantly above normal). The percentage of patients exceeding normal FDF-MD was 27.3 %, 60.7 %, and 87.9 % respectively. The age-adjusted FDF-mean defect (MD) of the G1X-protocol was not significantly correlated with refractive error, lens opacity, pupil size, or gender. Occurrence of ceiling effects (inability to detect targets at highest contrast) showed a high correlation with visual field losses (R = 0.72, p < 0.001). Local analysis indicates that SAP losses exceeding 5 dB could not be distinguished with the FDF technique. The FDF stimulus was able to detect beginning glaucoma damage. Patients with SAP-MD values exceeding 5 dB should be monitored with conventional perimetry because of its larger dynamic range.

Reduced transposed flicker noise in microwave oscillators using gaas-based feedforward amplifiers.

Science.gov (United States)

Everard, Jeremy K A; Broomfield, Carl D

2007-06-01

Transposed flicker noise reduction and removal is demonstrated in 7.6 GHz microwave oscillators for offsets greater than 10 kHz. This is achieved by using a GaAs-based feedforward power amplifier as the oscillation-sustaining stage and incorporating a limiter and resonator elsewhere in the loop. 20 dB noise suppression is demonstrated at 12.5 kHz offset when the error correcting amplifier is switched on. Three oscillator pairs have been built. A transmission line feedback oscillator with a Qo of 180 and two sapphire-based, dielectric resonator oscillators (DROs) with a Qo of 44,500. The difference between the two DROs is a change in the limiter threshold power level of 10 dB. The phase noise rolls-off at (1/f)(2) for offsets greater than 10 kHz for the transmission line oscillator and is set by the thermal noise to within 0-1 dB of the theoretical minimum. The noise performance of the DROs is within 6-12 dB of the theory. Possible reasons for this discrepancy are presented.

SVC or VSC for reduction of voltage sags and flicker. Trends in power electronics

Energy Technology Data Exchange (ETDEWEB)

Haeusler, M; Schnettler, A [ABB Calor Emag Schaltanlagen AG, Mannheim (Germany); Halvarsson, P [ABB Power Systems AB, Vaesteraas (Sweden)

1997-07-01

In the past complaints about insufficient power quality were often caused by flicker observed in the neighbourhood of industrial networks. Voltage sags due to faults in the power system pass, however, mostly unnoticed as not-so-common events. Now electronic controls are penetrating more and more in industry. Electronic controllers on factory machines - particularly those for variable speed motors - are vulnerable to voltage sags. A one-tenth second sag can cause a $200.000 downtime incident in a big factory. Therefore the demands on power quality are rising in industry as well. The costly separation in clean networks for residential areas and dirty networks for industrial grids is no perfect solution to avoid such problems. Static VAr Compensators (SVC) are traditionally one means to control the voltage in industrial networks. Because of the recent development of powerful gate turn-off semiconductor devices another type of converter has gained new interest for mitigation of system disturbances, the voltage-source converter (VSC). The characteristics of both types of power electronics in view of their possibilities for this application are presented. (orig.)

The rotation of accretion-disks and the power spectra of X-rays 'flickering'

International Nuclear Information System (INIS)

Zhang Xiaohe; Bao Gang

1990-07-01

The X-ray producing, inner region of the accretion disk in Active Galactic Nuclei (AGN) is likely to be non-stationary and non-axisymmetric. This non-stationarity and non-axisymmetry in disk surface brightness may be modeled by considering the pre-sense of many 'hot spots' on a steady, axisymmetric disk. As long as a 'spot' can survive for a few orbital periods, its orbital frequency can be introduced into the light curve either by relativistic orbital motion or by eclipsing of the spot by the disk. These rotational effects vary with the local properties of the spot population. Depending on the radial variation of spot brightness, lifetime and number density, the observed variability power spectrum may differ from that due to the intrinsic variability of spots alone, within the orbital frequency range in which these spots occur. In this paper, we explore the relation between properties assumed for the spot population and the resulting predictions for the observed variability. The implications of our results for the 'flickering' of X-ray sources powered by accretion disks (both AGN and galactic sources) are also discussed. (author). 24 refs, 6 figs

Emotion has no impact on attention in a change detection flicker task

Directory of Open Access Journals (Sweden)

Robert Colin Alan Bendall

2015-10-01

Full Text Available Past research provides conflicting findings regarding the influence of emotion on visual attention. Early studies suggested a broadening of attentional resources in relation to positive mood. However, more recent evidence indicates that positive emotions may not have a beneficial impact on attention, and that the relationship between emotion and attention may be mitigated by factors such as task demand or stimulus valence. The current study explored the effect of emotion on attention using the change detection flicker paradigm. Participants were induced into positive, neutral, and negative mood states and then completed a change detection task. A series of neutral scenes were presented and participants had to identify the location of a disappearing item in each scene. The change was made to the centre or the periphery of each scene and it was predicted that peripheral changes would be detected quicker in the positive mood condition and slower in the negative mood condition, compared to the neutral condition. In contrast to previous findings emotion had no influence on attention and whilst central changes were detected faster than peripheral changes, change blindness was not affected by mood. The findings suggest that the relationship between emotion and visual attention is influenced by the characteristics of a task, and any beneficial impact of positive emotion may be related to processing style rather than a broadening of attentional resources.

Modulation of enrofloxacin binding in OmpF by Mg2+ as revealed by the analysis of fast flickering single-porin current

Science.gov (United States)

Brauser, Annemarie; Schroeder, Indra; Gutsmann, Thomas; Cosentino, Cristian; Moroni, Anna; Winterhalter, Mathias

2012-01-01

One major determinant of the efficacy of antibiotics on Gram-negative bacteria is the passage through the outer membrane. During transport of the fluoroquinolone enrofloxacin through the trimeric outer membrane protein OmpF of Escherichia coli, the antibiotic interacts with two binding sites within the pore, thus partially blocking the ionic current. The modulation of one affinity site by Mg2+ reveals further details of binding sites and binding kinetics. At positive membrane potentials, the slow blocking events induced by enrofloxacin in Mg2+-free media are converted to flickery sojourns at the highest apparent current level (all three pores flickering). This indicates weaker binding in the presence of Mg2+. Analysis of the resulting amplitude histograms with β distributions revealed the rate constants of blocking (kOB) and unblocking (kBO) in the range of 1,000 to 120,000 s−1. As expected for a bimolecular reaction, kOB was proportional to blocker concentration and kBO independent of it. kOB was approximately three times lower for enrofloxacin coming from the cis side than from the trans side. The block was not complete, leading to a residual conductivity of the blocked state being ∼25% of that of the open state. Interpretation of the results has led to the following model: fast flickering as caused by interaction of Mg2+ and enrofloxacin is related to the binding site at the trans side, whereas the cis site mediates slow blocking events which are also found without Mg2+. The difference in the accessibility of the binding sites also explains the dependency of kOB on the side of enrofloxacin addition and yields a means of determining the most plausible orientation of OmpF in the bilayer. The voltage dependence suggests that the dipole of the antibiotic has to be adequately oriented to facilitate binding. PMID:22689827

Quantum fluctuations of the Coulomb potential as a source of flicker noise: the influence of external electric field

International Nuclear Information System (INIS)

Kazakov, Kirill A

2006-01-01

Fluctuations of the electromagnetic field produced by quantized matter in an external electric field are investigated. A general expression for the power spectrum of fluctuations is derived within the long-range expansion. It is found that in the whole measured frequency band, the power spectrum of fluctuations exhibits an inverse frequency dependence. A general argument is given showing that for all practically relevant values of the electric field, the power spectrum of induced fluctuations is proportional to the field strength squared. As an illustration, the power spectrum is calculated explicitly using a kinetic model with a relaxation-type collision term. Finally, it is shown that the magnitude of fluctuations produced by a sample generally has a Gaussian distribution around its mean value, and its dependence on the sample geometry is determined. In particular, it is demonstrated that for geometrically similar samples the power spectrum is inversely proportional to the sample volume. Application of the results obtained to the problem of flicker noise is discussed

Radiology reading-caused fatigue and measurement of eye strain with critical flicker fusion frequency

International Nuclear Information System (INIS)

Maeda, Eriko; Yoshikawa, Takeharu; Hayashi, Naoto; Akai, Hiroyuki; Hanaoka, Shouhei; Sasaki, Hiroki; Matsuda, Izuru; Yoshioka, Naoki; Ohtomo, Kuni

2011-01-01

The aim of this study was to investigate eye fatigue that could impair diagnostic accuracy by measuring the critical flicker fusion frequency (CFFF) before and after reading. CFFF was measured before and after about 4 h of health checkup reading in seven healthy volunteer radiologists. A questionnaire was also completed on duration of sleep the night before the experiment, average duration of sleep, and subjective fatigue using a visual analog scale (corrected to a 0-1 scale, 0 indicating the worst fatigue ever experienced). After-reading subjective fatigue was significantly greater (before 0.52±0.15, after 0.42±0.15), and CFFF was significantly lower (before 40.9±2.4, after 39.9±2.0). There was no significant correlation between subjective fatigue and CFFF, either before or after or between before- and after-reading differences in subjective fatigue and CFFF. Shorter duration of sleep the night before significantly correlated with lower CFFF (Pearson's correlation coefficient): before 0.42, P=0.0047; after 0.52, P=0.0003. CFFF declines after reading and can be considered useful as an indicator of fatigue induced by radiology reading. CFFF declines significantly when sleep is reduced the day before reading without correlation with subjective fatigue, meaning that sleep deprivation can cause an unaware decline in visual function. (author)

Reliability of Heterochromatic Flicker Photometry in Measuring Macular Pigment Optical Density among Preadolescent Children

Directory of Open Access Journals (Sweden)

Sasha M. McCorkle

2015-10-01

Full Text Available Macular pigment optical density (MPOD—assessed using customized heterochromatic flicker photometry (cHFP—is related to better cognition and brain lutein among adults. However, the reliability of MPOD assessed by cHFP has not been investigated in children. We assessed inter-session reliability of MPOD using modified cHFP. 7–10-year-olds (n = 66 underwent cHFP over 2 visits using 11 examiners. Reliability was also assessed in a subsample (n = 46 with only 2 examiners. Among all participants, there was no significant difference between the two sessions (p = 0.59—session 1: 0.61 ± 0.28; session 2: 0.62 ± 0.27. There was no significant difference in the MPOD of boys vs. girls (p = 0.56. There was a significant correlation between sessions (Y = 0.52x + 0.31; R2 = 0.29, p ≤ 0.005, with a reliability of 0.70 (Cronbach’s α. Among the subsample with 2 examiners, there was a significant correlation between sessions (Y = 0.54x + 0.31; R2 = 0.32, p < 0.005, with a reliability of 0.72 (Cronbach’s α. In conclusion, there is moderate reliability for modified cHFP to measure MPOD in preadolescents. These findings provide support for future studies aiming to conduct noninvasive assessments of retinal xanthophylls and study their association with cognition during childhood.

Reliability characterization of SiON and MGHK MOSFETs using flicker noise and its correlation with the bias temperature instability

Science.gov (United States)

Samnakay, Rameez; Balandin, Alexander A.; Srinivasan, Purushothaman

2017-09-01

Bias temperature instability (BTI) is one of the critical device degradation mechanisms in poly-Si/SiON and metal gate/high-k complementary metal-oxide-semiconductor (CMOS) technologies. Using the pre- and post-BTI flicker noise measurements, we investigated the bulk trap density, Nt, in both of these technologies. The low-frequency noise spectra were predominantly of 1/fγ type with γ engineering team at Globalfoundries, Inc. during the summer of 2014. He has currently authored or co-authored 10 journal publications and numerous conference presentations. His current research interests include 1/f noise in high-k dielectrics and fabricated 2D van der Waal thin-film devices Mr. Samnakay's awards and honors include the Dean's Distinguished Fellowship Award (University of California-Riverside) and induction into the IEEE-HKN honors society. He also serves as a reviewer for 6 journals including Applied Physics Letters, Journal of Physics: Condensed Matter and Nanotechnology journals.

Modality Switching in a Property Verification Task: An ERP Study of What Happens When Candles Flicker after High Heels Click.

Science.gov (United States)

Collins, Jennifer; Pecher, Diane; Zeelenberg, René; Coulson, Seana

2011-01-01

The perceptual modalities associated with property words, such as flicker or click, have previously been demonstrated to affect subsequent property verification judgments (Pecher et al., 2003). Known as the conceptual modality switch effect, this finding supports the claim that brain systems for perception and action help subserve the representation of concepts. The present study addressed the cognitive and neural substrate of this effect by recording event-related potentials (ERPs) as participants performed a property verification task with visual or auditory properties in key trials. We found that for visual property verifications, modality switching was associated with an increased amplitude N400. For auditory verifications, switching led to a larger late positive complex. Observed ERP effects of modality switching suggest property words access perceptual brain systems. Moreover, the timing and pattern of the effects suggest perceptual systems impact the decision-making stage in the verification of auditory properties, and the semantic stage in the verification of visual properties.

Modelos de horno de arco eléctrico para estudios del efecto flicker

Directory of Open Access Journals (Sweden)

Catalina González Castaño

2016-06-01

Full Text Available Objetivo: El objetivo de este artículo es evaluar las fluctuaciones de voltaje o flicker de dos modelos de un horno de arco eléctrico a través de la comparación con datos reales. Método: El primer modelo se fundamenta a partir del principio de conservación de la energía, de la cual se obtiene una ecuación diferencial no lineal que captura la característica voltaje – corriente del arco eléctrico. Las fluctuaciones de voltaje se generan con un circuito de caos que modula la amplitud del voltaje del arco eléctrico. El segundo modelo está basado en las relaciones empíricas entre la longitud de arco, la tensión y la corriente a través del arco. Las fluctuaciones de voltaje se obtienen agregando una señal aleatoria a la longitud del arco eléctrico. Ambos modelos son implementados en PSCADTM. Resultados: Los resultados de ambos modelos son comparados con mediciones reales tomadas en la etapa más crítica de la operación del horno, y muestran que el modelo basado en la conservación de la potencia presenta un menor error medio cuadrático promedio en los voltajes y corrientes de 5,6 V y 1.7 kA frente a 27,2 V y 3.38 kA obtenidos con el segundo modelo. Conclusiones: Ambos modelos consideran la no linealidad y comportamiento aleatorio que exhibe este tipo de carga, validando su inclusión en modelos computacionales de sistemas eléctricos de potencia.

A contingency-based approach to the etiology of 'disorganized' attachment: the 'flickering switch' hypothesis.

Science.gov (United States)

Koós, O; Gergely, G

2001-01-01

The authors present a new approach to the etiology of disorganized attachment based on contingency detection theory. According to this view, the relevant common factor in parental maltreatment and unresolved loss that leads to disorganized attachment has to do with the type of "deviant contingency environment" that both of these conditions generate. In such environments, infants experience periods of being in control followed by periods of sudden loss of control over the caregiver's behavior. The authors hypothesize that this adversely affects the developmental unfolding of the infant's innate "contingency detection module" (Gergely & Watson, 1999), which normally involves a maturational shift around 3 months from an initial attention bias for perfectly contingent stimulation to an emerging preference for less-than-perfect social contingencies. The periodically changing controllability of abusive and dissociating "unresolved" attachment figures is hypothesized to block this process and to lead to the defensive fixation of a dysfunctional "flickering contingency switch" mechanism with two dominant and competing target positions (self-oriented vs. other-oriented). This results in the dissociative style of attention and behavioral organization characteristic of disorganized infant attachment. The authors summarize the preliminary results of an empirical study that provides support for this model in 6.5-month-old infants using a modified Still-Face situation (the Mirror Interaction Situation). The study demonstrates differential emotional and behavioral reactions to sudden loss of maternal contingency and a specific interest in exploring the perfectly contingent self-image in the mirror in infants who at 12 months become categorized as "disorganized" in the Strange Situation.

[Investigation of the distribution of water clusters in vegetables, fruits, and natural waters by flicker noise spectroscopy].

Science.gov (United States)

Zubov, A V; Zubov, K V; Zubov, V A

2007-01-01

The distribution of water clusters in fresh rain water and in rain water that was aged for 30 days (North Germany, 53 degrees 33' N, 12 degrees 47' E, 293 K, rain on 25.06.06) as well as in fresh vegetables and fruits was studied by flicker noise spectroscopy. In addition, the development of water clusters in apples and potatoes during ripening in 2006 was investigated. A different distribution of water clusters in irrigation water (river and rain) and in the biomatrix of vegetables (potatoes, onions, tomatoes, red beets) and fruits (apples, bananas) was observed. It was concluded that the cluster structure of irrigation water differs from that of water of the biomatrix of vegetables and fruits and depends on drought and the biomatrix nature. Water clusters in plants are more stable and reproducible than water clusters in natural water. The main characteristics of cluster formation in materials studied were given. The oscillation frequencies of water clusters in plants (biofield) are given at which they interact with water clusters of the Earth hydrosphere. A model of series of clusters 16(H2O)100 4(H2O)402 2(H2O)903 (H2O)1889 in the biomatrix of vegetables and fruits was discussed.

Flickering AGN can explain the strong circumgalactic O VI observed by COS-Halos

Science.gov (United States)

Oppenheimer, Benjamin D.; Segers, Marijke; Schaye, Joop; Richings, Alexander J.; Crain, Robert A.

2018-03-01

Proximity zone fossils (PZFs) are ionization signatures around recently active galactic nuclei (AGNs) where metal species in the circumgalactic medium remain overionized after the AGNs have shut off due to their long recombination time scales. We explore cosmological zoom hydrodynamic simulations, using the EAGLE (Evolution and Assembly of GaLaxies and their Environments) model paired with a non-equilibrium ionization and cooling module including time-variable AGN radiation to model PZFs around star-forming disc galaxies in the z ˜ 0.2 Universe. Previous simulations typically underestimated the O VI content of galactic haloes, but we show that plausible PZF models increase O VI column densities by 2 - 3 × to achieve the levels observed around COS-Halos star-forming galaxies out to 150 kpc. Models with AGN bolometric luminosities ≳ 1043.6erg s- 1, duty cycle fractions ≲ 10 per cent, and AGN lifetimes ≲ 106 yr are the most promising, because their supermassive black holes grow at the cosmologically expected rate and they mostly appear as inactive AGN, consistent with COS-Halos. The central requirement is that the typical star-forming galaxy hosted an active AGN within a time-scale comparable to the recombination time of a high metal ion, which for circumgalactic O VI is ≈107 yr. H I, by contrast, returns to equilibrium much more rapidly due to its low neutral fraction and does not show a significant PZF effect. O VI absorption features originating from PZFs appear narrow, indicating photoionization, and are often well aligned with lower metal ion species. PZFs are highly likely to affect the physical interpretation of circumgalactic high ionization metal lines if, as expected, normal galaxies host flickering AGN.

Experimental and numerical study of impact of voltage fluctuate, flicker and power factor wave electric generator to local distribution

Science.gov (United States)

Hadi, Nik Azran Ab; Rashid, Wan Norhisyam Abd; Hashim, Nik Mohd Zarifie; Mohamad, Najmiah Radiah; Kadmin, Ahmad Fauzan

2017-10-01

Electricity is the most powerful energy source in the world. Engineer and technologist combined and cooperated to invent a new low-cost technology and free carbon emission where the carbon emission issue is a major concern now due to global warming. Renewable energy sources such as hydro, wind and wave are becoming widespread to reduce the carbon emissions, on the other hand, this effort needs several novel methods, techniques and technologies compared to coal-based power. Power quality of renewable sources needs in depth research and endless study to improve renewable energy technologies. The aim of this project is to investigate the impact of renewable electric generator on its local distribution system. The power farm was designed to connect to the local distribution system and it will be investigated and analyzed to make sure that energy which is supplied to customer is clean. The MATLAB tools are used to simulate the overall analysis. At the end of the project, a summary of identifying various voltage fluctuates data sources is presented in terms of voltage flicker. A suggestion of the analysis impact of wave power generation on its local distribution is also presented for the development of wave generator farms.

LARGER PLANET RADII INFERRED FROM STELLAR ''FLICKER'' BRIGHTNESS VARIATIONS OF BRIGHT PLANET-HOST STARS

International Nuclear Information System (INIS)

Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua

2014-01-01

Most extrasolar planets have been detected by their influence on their parent star, typically either gravitationally (the Doppler method) or by the small dip in brightness as the planet blocks a portion of the star (the transit method). Therefore, the accuracy with which we know the masses and radii of extrasolar planets depends directly on how well we know those of the stars, the latter usually determined from the measured stellar surface gravity, log g. Recent work has demonstrated that the short-timescale brightness variations ( f licker ) of stars can be used to measure log g to a high accuracy of ∼0.1-0.2 dex. Here, we use flicker measurements of 289 bright (Kepmag < 13) candidate planet-hosting stars with T eff = 4500-6650 K to re-assess the stellar parameters and determine the resulting impact on derived planet properties. This re-assessment reveals that for the brightest planet-host stars, Malmquist bias contaminates the stellar sample with evolved stars: nearly 50% of the bright planet-host stars are subgiants. As a result, the stellar radii, and hence the radii of the planets orbiting these stars, are on average 20%-30% larger than previous measurements had suggested

Evidence of Flicker-Induced Functional Hyperaemia in the Smallest Vessels of the Human Retinal Blood Supply.

Directory of Open Access Journals (Sweden)

Angelina Duan

Full Text Available Regional changes in blood flow are initiated within neural tissue to help fuel local differences in neural activity. Classically, this response was thought to arise only in larger arterioles and venules. However, recently, it has been proposed that a the smallest vessels of the circulation make a comparable contribution, and b the response should be localised intermittently along such vessels, due to the known distribution of contractile mural cells. To assess these hypotheses in human neural tissue in vivo, we imaged the retinal microvasculature (diameters 3-28 μm non-invasively, using adaptive optics, before and after delivery of focal (360 μm patches of flickering visible light. Our results demonstrated a definite average response in 35% of all vessel segments analysed. In these responding vessels, the magnitude of proportional dilation (mean ± SEM for pre-capillary arterioles 13 ± 5%, capillaries 31 ± 8%, and post-capillary venules 10 ± 3% is generally far greater than the magnitudes we and others have measured in the larger retinal vessels, supporting proposition a above. The dilations observed in venules were unexpected based on previous animal work, and may be attributed either to differences in stimulus or species. Response heterogeneity across the network was high; responses were also heterogeneous along individual vessels (45% of vessel segments showed demonstrable locality in their response. These observations support proposition b above. We also observed a definite average constriction across 7% of vessel segments (mean ± SEM constriction for capillaries -16 ± 3.2%, and post-capillary venules -18 ± 12%, which paints a picture of dynamic redistribution of flow throughout the smallest vessel networks in the retina in response to local, stimulus-driven metabolic demand.

Perimetric measurements with flicker-defined form stimulation in comparison with conventional perimetry and retinal nerve fiber measurements.

Science.gov (United States)

Horn, Folkert K; Tornow, Ralf P; Jünemann, Anselm G; Laemmer, Robert; Kremers, Jan

2014-04-11

We compared the results of flicker-defined form (FDF) perimetry with standard automated perimetry (SAP) and retinal nerve fiber layer (RNFL) thickness measurements using spectral domain optical coherence tomography (OCT). A total of 64 healthy subjects, 45 ocular hypertensive patients, and 97 "early" open-angle glaucoma (OAG) patients participated in this study. Definition of glaucoma was based exclusively on glaucomatous optic disc appearance. All subjects underwent FDF perimetry, SAP, and peripapillary measurements of the RNFL thickness. The FDF perimetry and SAP were performed at identical test locations (G1 protocol). Exclusion criteria were subjects younger than 34 years, SAP mean defect (SAP MD) > 5 dB, eye diseases other than glaucoma, or nonreliable FDF measurements. The correlations between the perimetric data on one hand and RNFL thicknesses on the other hand were analyzed statistically. The age-corrected sensitivity values and the local results from the controls were used to determine FDF mean defect (FDF MD). The FDF perimetry and SAP showed high concordance in this cohort of experienced patients (MD values, R = -0.69, P < 0.001). Of a total of 42 OAG patients with abnormal SAP MD, 38 also displayed abnormal FDF MD. However, FDF MD was abnormal in 28 of 55 OAG patients with normal SAP MD. The FDF MD was significantly (R = -0.61, P < 0.001) correlated with RNFL thickness with a (nonsignificantly) larger correlation coefficient than conventional SAP MD (R = -0.48, P < 0.001). The FDF perimetry is able to uncover functional changes concurrent with the changes in RNFL thickness. The FDF perimetry may be an efficient functional test to detect early glaucomatous nerve atrophy. (ClinicalTrials.gov number, NCT00494923.).

Effects of flickering light on refraction and changes in eye axial length of C57BL/6 mice.

Science.gov (United States)

Yu, Ying; Chen, Hui; Tuo, Jingsheng; Zhu, Yin

2011-01-01

To investigate the effectiveness and feasibility of inducing myopia in mice by flickering-light (FL) stimulation. Forty-five 28-day-old C57BL/6 (B6) mice were randomly assigned to three groups: control group, FL stimulation group and form deprivation (FD) group. Mice in the control group were raised under 250 lux illumination from 8:00 a.m. to 8:00 p.m. Mice in the FL group were raised under illumination with a duty cycle of 50% at a flash rate of 2 Hz from 8:00 a.m. to 8:00 p.m. for 6 weeks. Mice in the FD group were raised under the same conditions as the control group; the right eyes of the mice were covered with semitransparent hemispherical plastic shells serving as eye diffusers. The refractive state and axial length (AL) of the right eyes were measured by eccentric infrared photorefraction and A-scan ultrasonography, respectively, before treatment and after 2, 4, 6 or 8 weeks' treatment. After 6 weeks' exposure to FL, the refraction became more myopic compared with the control group as indicated by longer AL compared with the control group (p < 0.05); the FD eyes were more myopic than the FL eyes (p < 0.05). However, some mice lost their eye diffusers, and lens opacities were found. Myopia can be induced by FL in B6 mice. The myopic shift induced by FL is less than that induced by FD, but FL causes fewer side effects, and is safery and easier to manipulate. Copyright © 2011 S. Karger AG, Basel.

Effects Of Local Oscillator Errors On Digital Beamforming

Science.gov (United States)

2016-03-01

processor EF element factor EW electronic warfare FFM flicker frequency modulation FOV field-of-view FPGA field-programmable gate array FPM flicker...frequencies and also more difficult to measure [15]. 2. Flicker frequency modulation The source for flicker frequency modulation ( FFM ) is attributed to...a physical resonance mechanism of an oscillator or issues controlling electronic components. Some oscillators might not show FFM noise, which might

Radial velocity variations of photometrically quiet, chromospherically inactive Kepler stars: A link between RV jitter and photometric flicker

Energy Technology Data Exchange (ETDEWEB)

Bastien, Fabienne A.; Stassun, Keivan G.; Pepper, Joshua [Physics and Astronomy Department, Vanderbilt University, 1807 Station B, Nashville, TN 37235 (United States); Wright, Jason T. [Center for Exoplanets and Habitable Worlds, 525 Davey Laboratory, The Pennsylvania State University, University Park, PA 16803 (United States); Aigrain, Suzanne [Sub-department of Astrophysics, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom); Basri, Gibor [Astronomy Department, University of California, Berkeley, CA 94720 (United States); Johnson, John A. [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Walkowicz, Lucianne M. [Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544 (United States)

2014-02-01

We compare stellar photometric variability, as measured from Kepler light curves by Basri et al., with measurements of radial velocity (RV) rms variations of all California Planet Search overlap stars. We newly derive rotation periods from the Kepler light curves for all of the stars in our study sample. The RV variations reported herein range from less than 4 to 135 m s{sup –1}, yet the stars all have amplitudes of photometric variability less than 3 mmag, reflecting the preference of the RV program for chromospherically 'quiet' stars. Despite the small size of our sample, we find with high statistical significance that the RV rms manifests strongly in the Fourier power spectrum of the light curve: stars that are noisier in RV have a greater number of frequency components in the light curve. We also find that spot models of the observed light curves systematically underpredict the observed RV variations by factors of ∼2-1000, likely because the low-level photometric variations in our sample are driven by processes not included in simple spot models. The stars best fit by these models tend to have simpler light curves, dominated by a single relatively high-amplitude component of variability. Finally, we demonstrate that the RV rms behavior of our sample can be explained in the context of the photometric variability evolutionary diagram introduced by Bastien et al. We use this diagram to derive the surface gravities of the stars in our sample, revealing many of them to have moved off the main sequence. More generally, we find that the stars with the largest RV rms are those that have evolved onto the 'flicker floor' sequence in that diagram, characterized by relatively low amplitude but highly complex photometric variations which grow as the stars evolve to become subgiants.

Which lamp will be optimum to eye? Incandescent, fluorescent or LED etc

Directory of Open Access Journals (Sweden)

Liang Chen

2014-02-01

Full Text Available Low frequency flicker, high frequency flicker, strong light, strong blue light, infrared, ultraviolet, electromagnetic radiation, ripple flicker and dimming flicker produced by different lamps have negative impact on vision, eyes and health. Negative impact on eyes resulting in myopia or cataract etc:the solution is to remove all the negative factors by applying upright lighting technology and that is optimum to vision, eyes and health.

Implementation of an Optical Readout System for High-Sensitivity Terahertz Microelectromechanical Sensor Array

Science.gov (United States)

2014-09-01

rod moves about the illumination scene, the pixels in the detector start to flicker . The ‘ flickering ’ effect is due to the metal rod blocking THz...still possible to mitigate convective heat exchange between the sensor and the ambient surroundings. To mitigate the effects of convective heat...detector start to flicker . The ‘ flickering ’ effect is due to the metal rod blocking THz radiation. This effect is more apparent in the video

Training for Defense? From Stochastic Traits to Synchrony in Giant Honey Bees (Apis dorsata).

Science.gov (United States)

Weihmann, Frank; Hoetzl, Thomas; Kastberger, Gerald

2012-08-30

In Giant Honey Bees, abdomen flipping happens in a variety of contexts. It can be either synchronous or cascaded, such as in the collective defense traits of shimmering and rearing-up, or it can happen as single-agent behavior. Abdomen flipping is also involved in flickering behavior, which occurs regularly under quiescent colony state displaying singular or collective traits, with stochastic, and (semi-) synchronized properties. It presumably acts via visual, mechanoceptive, and pheromonal pathways and its goals are still unknown. This study questions whether flickering is preliminary to shimmering which is subject of the fs (flickering-shimmering)-transition hypothesis? We tested the respective prediction that trigger sites (ts) at the nest surface (where shimmering waves had been generated) show higher flickering activity than the alternative non-trigger sites (nts). We measured the flickering activity of ts- and nts-surface bees from two experimental nests, before and after the colony had been aroused by a dummy wasp. Arousal increased rate and intensity of the flickering activity of both ts- and nts cohorts (P < 0.05), whereby the flickering intensity of ts-bees were higher than that of nts-bees (P < 0.05). Under arousal, the colonies also increased the number of flickering-active ts- and nts-cohorts (P < 0.05). This provides evidence that cohorts which are specialist at launching shimmering waves are found across the quiescent nest zone. It also proves that arousal may reinforce the responsiveness of quiescent curtain bees for participating in shimmering, practically by recruiting additional trigger site bees for expanding repetition of rate and intensity of shimmering waves. This finding confirms the fs-transition hypothesis and constitutes evidence that flickering is part of a basal colony-intrinsic information system. Furthermore, the findings disprove that the muscle activity associated with flickering would heat up the surface bees. Hence, surface bees

Voltage Quality of Grid Connected Wind Turbines

DEFF Research Database (Denmark)

Chen, Zhe; Blaabjerg, Frede; Sun, Tao

2004-01-01

Grid connected wind turbines may cause quality problems, such as voltage variation and flicker. This paper discusses the voltage variation and flicker emission of grid connected wind turbines with doubly-fed induction generators. A method to compensate flicker by using a voltage source converter...

Flicker licker

Energy Technology Data Exchange (ETDEWEB)

Dooley, T.

1988-02-24

Discusses the use of high frequency (h.f.) electronic ballasts to control fluorescent lighting. H.F. ballasts consume about 25% less power than conventional, switch-start control gear to produce the same light intensity. They eliminate stuttering starts and, according to a recent report, halve the number of headaches caused by lamps operating on a conventional 50Hz supply. H.F. ballasts are also smaller, lighter and have fewer parts than conventional ballasts, but they are more expensive. The high power factor in h.f. lighting gives two further advantages - one is lower demand on the building's ventilation system because the lamps produce less heat. Another benefit from low power consumption is an increase in a lamp's useful life. It is estimated that 2 years is a realistic payback on h.f. lighting in offices where lights are on about 12 hours per day. Sales in h.f. ballasts are now beginning to accelerate. There is a consensus between manufacturers to make their ballasts compatible with a range of fluorescent lamps. The exception is Phillips, who have chosen an argon lamp specially designed for use with its h.f. ballast. Their strategy is based on dimmer control - argon lamps are easier to dim smoothly than krypton lamps. Dimming allows adjustment of light levels to suit a given job and can also be used as part of an energy management system to dim or raise the lighting levels according to conditions.

Training for Defense? From Stochastic Traits to Synchrony in Giant Honey Bees (Apis dorsata

Directory of Open Access Journals (Sweden)

Gerald Kastberger

2012-08-01

Full Text Available In Giant Honey Bees, abdomen flipping happens in a variety of contexts. It can be either synchronous or cascaded, such as in the collective defense traits of shimmering and rearing-up, or it can happen as single-agent behavior. Abdomen flipping is also involved in flickering behavior, which occurs regularly under quiescent colony state displaying singular or collective traits, with stochastic, and (semi- synchronized properties. It presumably acts via visual, mechanoceptive, and pheromonal pathways and its goals are still unknown. This study questions whether flickering is preliminary to shimmering which is subject of the fs (flickering-shimmering-transition hypothesis? We tested the respective prediction that trigger sites (ts at the nest surface (where shimmering waves had been generated show higher flickering activity than the alternative non-trigger sites (nts. We measured the flickering activity of ts- and nts-surface bees from two experimental nests, before and after the colony had been aroused by a dummy wasp. Arousal increased rate and intensity of the flickering activity of both ts- and nts cohorts (P < 0.05, whereby the flickering intensity of ts-bees were higher than that of nts-bees (P < 0.05. Under arousal, the colonies also increased the number of flickering-active ts- and nts-cohorts (P < 0.05. This provides evidence that cohorts which are specialist at launching shimmering waves are found across the quiescent nest zone. It also proves that arousal may reinforce the responsiveness of quiescent curtain bees for participating in shimmering, practically by recruiting additional trigger site bees for expanding repetition of rate and intensity of shimmering waves. This finding confirms the fs-transition hypothesis and constitutes evidence that flickering is part of a basal colony-intrinsic information system

A noninvasive brain computer interface using visually-induced near-infrared spectroscopy responses.

Science.gov (United States)

Chen, Cheng-Hsuan; Ho, Ming-Shan; Shyu, Kuo-Kai; Hsu, Kou-Cheng; Wang, Kuo-Wei; Lee, Po-Lei

2014-09-19

Visually-induced near-infrared spectroscopy (NIRS) response was utilized to design a brain computer interface (BCI) system. Four circular checkerboards driven by distinct flickering sequences were displayed on a LCD screen as visual stimuli to induce subjects' NIRS responses. Each flickering sequence was a concatenated sequence of alternative flickering segments and resting segments. The flickering segment was designed with fixed duration of 3s whereas the resting segment was chosen randomly within 15-20s to create the mutual independencies among different flickering sequences. Six subjects were recruited in this study and subjects were requested to gaze at the four visual stimuli one-after-one in a random order. Since visual responses in human brain are time-locked to the onsets of visual stimuli and the flicker sequences of distinct visual stimuli were designed mutually independent, the NIRS responses induced by user's gazed targets can be discerned from non-gazed targets by applying a simple averaging process. The accuracies for the six subjects were higher than 90% after 10 or more epochs being averaged. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Numerical and Experimental Study on Negative Buoyance Induced Vortices in N-Butane Jet Flames

KAUST Repository

Xiong, Yuan

2015-07-26

Near nozzle flow field in flickering n-butane diffusion jet flames was investigated with a special focus on transient flow patterns of negative buoyance induced vortices. The flow structures were obtained through Mie scattering imaging with seed particles in a fuel stream using continuous-wave (CW) Argon-ion laser. Velocity fields were also quantified with particle mage velocimetry (PIV) system having kHz repetition rate. The results showed that the dynamic motion of negative buoyance induced vortices near the nozzle exit was coupled strongly with a flame flickering instability. Typically during the flame flickering, the negative buoyant vortices oscillated at the flickering frequency. The vortices were distorted by the flickering motion and exhibited complicated transient vortical patterns, such as tilting and stretching. Numerical simulations were also implemented based on an open source C++ package, LaminarSMOKE, for further validations.

Power Quality of Grid-Connected Wind Turbines with DFIG and Their Interaction with the Grid

DEFF Research Database (Denmark)

Sun, Tao

quality issues of grid-connected wind turbines and the interaction between wind turbines and the grid. The specific goal of the research has been to investigate flicker emission and mitigation of grid-connected wind turbines with doubly fed induction generators (DFIG) during continuous operation...... measures are proposed to mitigate the flicker levels produced by grid-connected wind turbines with DFIG, respectively by wind turbine output reactive power control and using STATCOM. Simulation results demonstrate that these two measures are effective for flicker mitigation regardless of mean wind speed....... To evaluate the flicker levels produced by grid-connected wind turbines with DFIG, a flickermeter model is developed according to the IEC standard IEC 61000-4-15, which simulates the response of the lamp-eye-brain chain and provides on-line statistical analysis ofthe flicker signal and the final results...

FLICKERING OF 1.3 cm SOURCES IN SGR B2: TOWARD A SOLUTION TO THE ULTRACOMPACT H II REGION LIFETIME PROBLEM

Energy Technology Data Exchange (ETDEWEB)

De Pree, C. G.; Monsrud, A. [Agnes Scott College, 141 East College Avenue, Decatur, GA 30030 (United States); Peters, T. [Institut für Theoretische Physik, Universität Zürich, CH-8057 Zürich (Switzerland); Mac Low, M.-M. [American Museum of Natural History, New York, NY 10024 (United States); Wilner, D. J.; Keto, E. R. [Harvard-Smithsonian CfA, Cambridge, MA 02138 (United States); Goss, W. M. [National Radio Astronomy Observatory, Socorro, NM 87801 (United States); Galván-Madrid, R. [European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching (Germany); Klessen, R. S. [Zentrum für Astronomie, Institut für Theoretische Astrophysik, Universität Heidelberg, Albert-Ueberle-Str. 2, D-69120 Heidelberg (Germany)

2014-02-01

Accretion flows onto massive stars must transfer mass so quickly that they are themselves gravitationally unstable, forming dense clumps and filaments. These density perturbations interact with young massive stars, emitting ionizing radiation, alternately exposing and confining their H II regions. As a result, the H II regions are predicted to flicker in flux density over periods of decades to centuries rather than increase monotonically in size as predicted by simple Spitzer solutions. We have recently observed the Sgr B2 region at 1.3 cm with the Very Large Array in its three hybrid configurations (DnC, CnB, and BnA) at a resolution of ∼0.''25. These observations were made to compare in detail with matched continuum observations from 1989. At 0.''25 resolution, Sgr B2 contains 41 ultracompact (UC) H II regions, 6 of which are hypercompact. The new observations of Sgr B2 allow comparison of relative peak flux densities for the H II regions in Sgr B2 over a 23 year time baseline (1989-2012) in one of the most source-rich massive star forming regions in the Milky Way. The new 1.3 cm continuum images indicate that four of the 41 UC H II regions exhibit significant changes in their peak flux density, with one source (K3) dropping in peak flux density, and the other three sources (F10.303, F1, and F3) increasing in peak flux density. The results are consistent with statistical predictions from simulations of high mass star formation, suggesting that they offer a solution to the lifetime problem for UC H II regions.

Diagnostic capability of Pulsar perimetry in pre-perimetric and early glaucoma.

Science.gov (United States)

Hirasawa, Kazunori; Takahashi, Natsumi; Matsumura, Kazuhiro; Kasahara, Masayuki; Shoji, Nobuyuki

2017-06-12

This study aimed to compare the diagnostic capability of Pulsar perimetry (Pulsar) in pre-perimetric glaucoma (PPG) and early glaucoma (EG) with that of Flicker perimetry (Flicker) and spectral-domain optical conference tomography (SD-OCT). This prospective cross-sectional study included 25 eyes of 25 PPG patients, 35 eyes of 35 EG patients, and 42 eyes of 42 healthy participants. The diagnostic capability using the area under the curve (AUC) of the best parameter and agreement of detectability between structural and functional measurements were compared. For PPG patients, the AUC of Pulsar, Flicker, OCT-disc, and OCT-macular was 0.733, 0.663, 0.842, and 0.780, respectively. The AUC of Flicker was significantly lower than that of OCT-disc (p = 0.016). For EG patients, the AUC of Pulsar, Flicker, OCT-disc, and OCT-macular were 0.851, 0.869, 0.907, and 0.861, respectively. There was no significant difference in AUC among these methods. The agreement between structural and functional measurements expressed by kappa value ranged from -0.16 to 0.07 for PPG and from 0.01 to 0.25 for EG. Although the diagnostic capability of Pulsar in the PPG and EG groups was equal to that of Flicker and SD-OCT, the agreements between structural and functional measurements for both PPG and EG were poor.

Operation of a P300-based brain-computer interface by individuals with cervical spinal cord injury.

Science.gov (United States)

Ikegami, Shiro; Takano, Kouji; Saeki, Naokatsu; Kansaku, Kenji

2011-05-01

This study evaluates the efficacy of a P300-based brain-computer interface (BCI) with green/blue flicker matrices for individuals with cervical spinal cord injury (SCI). Ten individuals with cervical SCI (age 26-53, all male) and 10 age- and sex-matched able-bodied controls (age 27-52, all male) with no prior BCI experience were asked to input hiragana (Japanese alphabet) characters using the P300 BCI with two distinct types of visual stimuli, white/gray and green/blue, in an 8×10 flicker matrix. Both online and offline performance were evaluated. The mean online accuracy of the SCI subjects was 88.0% for the white/gray and 90.7% for the green/blue flicker matrices. The accuracy of the control subjects was 77.3% and 86.0% for the white/gray and green/blue, respectively. There was a significant difference in online accuracy between the two types of flicker matrix. SCI subjects performed with greater accuracy than controls, but the main effect was not significant. Individuals with cervical SCI successfully controlled the P300 BCI, and the green/blue flicker matrices were associated with significantly higher accuracy than the white/gray matrices. The P300 BCI with the green/blue flicker matrices is effective for use not only in able-bodied subjects, but also in individuals with cervical SCI. Copyright © 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

Mitigation of voltage fluctuations with an Adaptive Var Compensator (AVC)

Energy Technology Data Exchange (ETDEWEB)

Chan, F [TransAlta Utilities Corp., Calgary, AB (Canada); Castanheira, A

1997-04-01

The installation of an Adaptive Var Compensator (AVC) to remedy a voltage flicker problem at the TIMEU sawmill in Fort Assiniboine, Alberta, was described. The TIMEU sawmill is a 980 kVA load at the end of a 25 kV feeder. Two older style J bar type saws, each driven by a 200 Hp motor, are used to operate the wood processing services. The sawing and chipping process resulted in the generation of significant voltage flicker on the 25 kV distribution system. The AVC provided cycle per cycle reactive compensation and voltage support; no further complaints of flicker were received.

Large wind farms in the electric power systems. Voltage quality and power dynamics. Final report; Store vindmoelleparker i elsystemet. Spaendingskvalitet og effektdynamik. Slutrapport

Energy Technology Data Exchange (ETDEWEB)

NONE

2003-12-01

The aim of the project has partly been to compare practical measurements with theoretical calculations in order to make quantitative evaluations of the consequences for the power system when large offshore wind farms are connected and partly to develop a regulation algorithm for control of offshore wind farm's power production meeting the demands of the connection conditions. A comparison between calculated flicker emissions and measured flicker emissions has shown that the IEC standard for calculation of flicker emissions from wind farms is conservative as the counterbalancing is underestimated. The calculated flicker emissions are approx. twice as big as the measured flicker emissions. A comparison between theoretical simulations of grid faults and measurement tests has shown satisfying correspondence. This has validated the newly developed theoretical models of offshore wind turbines for simulation of stability conditions in the power system. The validation has been an important element during evaluations of offshore wind turbines' effect on the operating stability of the power system and hereby the reliability of supply. A failsafe regulation algorithm for control of offshore wind farms maximum (instantaneous)production has been developed. The algorithm has been implemented and tested in practice and has proven to work satisfactory. (BA)

A new approach for power quality improvement of DFIG based wind farms connected to weak utility grid

Directory of Open Access Journals (Sweden)

Hossein Mahvash

2017-09-01

Full Text Available Most of power quality problems for grid connected doubly fed induction generators (DFIGs with wind turbine include flicker, variations of voltage RMS profile, and injected harmonics due to switching in DFIG converters. Flicker phenomenon is the most important problem in wind power systems. This paper described an effective method for mitigating flicker emission and power quality improvement for a fairly weak grid connected to a wind farm with DFIGs. The method was applied in the rotor side converter (RSC of the DFIG to control the output reactive power. q axis reference current was directly derived according to the mathematical relation between rotor q axis current and DFIG output reactive power without using PI controller. To extract the reference reactive power, the stator voltage control loop with the droop coefficient was proposed to regulate the grid voltage level in each operational condition. The DFIG output active power was separately controlled in d axis considering the stator voltage orientation control (SVOC. Different simulations were carried out on the test system and the flicker short term severity index (Pst was calculated for each case study using the discrete flickermeter model according to IEC 61400 standard. The obtained results validated flicker mitigation and power quality enhancement for the grid.

Predictive capability of average Stokes polarimetry for simulation of phase multilevel elements onto LCoS devices.

Science.gov (United States)

Martínez, Francisco J; Márquez, Andrés; Gallego, Sergi; Ortuño, Manuel; Francés, Jorge; Pascual, Inmaculada; Beléndez, Augusto

2015-02-20

Parallel-aligned (PA) liquid-crystal on silicon (LCoS) microdisplays are especially appealing in a wide range of spatial light modulation applications since they enable phase-only operation. Recently we proposed a novel polarimetric method, based on Stokes polarimetry, enabling the characterization of their linear retardance and the magnitude of their associated phase fluctuations or flicker, exhibited by many LCoS devices. In this work we apply the calibrated values obtained with this technique to show their capability to predict the performance of spatially varying phase multilevel elements displayed onto the PA-LCoS device. Specifically we address a series of multilevel phase blazed gratings. We analyze both their average diffraction efficiency ("static" analysis) and its associated time fluctuation ("dynamic" analysis). Two different electrical configuration files with different degrees of flicker are applied in order to evaluate the actual influence of flicker on the expected performance of the diffractive optical elements addressed. We obtain a good agreement between simulation and experiment, thus demonstrating the predictive capability of the calibration provided by the average Stokes polarimetric technique. Additionally, it is obtained that for electrical configurations with less than 30° amplitude for the flicker retardance, they may not influence the performance of the blazed gratings. In general, we demonstrate that the influence of flicker greatly diminishes when the number of quantization levels in the optical element increases.

Effects of Burner Configurations on the Natural Oscillation Characteristics of Laminar Jet Diffusion Flames

Directory of Open Access Journals (Sweden)

K. R. V. Manikantachari

2015-09-01

Full Text Available In this work, effects of burner configurations on the natural oscillations of methane laminar diffusion flames under atmospheric pressure and normal gravity conditions have been studied experimentally. Three regimes of laminar diffusion flames, namely, steady, intermittent flickering and continuous flickering have been investigated. Burner configurations such as straight pipe, contoured nozzle and that having an orifice plate at the exit have been considered. All burners have the same area of cross section at the exit and same burner lip thickness. Flame height data has been extracted from direct flame video using MATLAB. Shadowgraph videos have been captured to analyze the plume width characteristics. Results show that, the oscillation characteristics of the orifice burner is significantly different from the other two burners; orifice burner produces a shorter flame and wider thermal plume width in the steady flame regime and the onset of the oscillation/flickering regimes for the orifice burner occurs at a higher fuel flow rate. In the natural flickering regime, the dominating frequency of flame flickering remains within a small range, 12.5 Hz to 15 Hz, for all the burners and for all fuel flow rates. The time-averaged flame length-scale parameters, such as the maximum and the minimum flame heights, increase with respect to the fuel flow rate, however, the difference in the maximum and the minimum flame heights remains almost constant.

The Flickering Global City

Directory of Open Access Journals (Sweden)

Eric Slater

2015-08-01

Full Text Available This article explores new dimensions of the global city in light of the correlation between hegemonic transition and the prominence of financial centers. It counterposes Braudel’s historical sequence of dominant cities to extant approaches in the literature, shifting the emphasis from a convergence of form and function to variations in history and structure. The marked increase of finance in the composition of London, New York and Tokyo has paralleled each city’s occupation of a distinct niche in world financial markets: London is the principal center of currency exchange, New York is the primary equities market, and Tokyo is the leader in international banking. This division expresses the progression of world-economies since the nineteenth century and unfolds in the context of the present hegemonic transition. By combining world-historical and city-centered approaches, the article seeks to reframe the global city and overcome the limits inherent in the paradigm of globalization.

Short-timescale variability in cataclysmic binaries

International Nuclear Information System (INIS)

Cordova, F.A.; Mason, K.O.

1982-01-01

Rapid variability, including flickering and pulsations, has been detected in cataclysmic binaries at optical and x-ray frequencies. In the case of the novalike variable TT Arietis, simultaneous observations reveal that the x-ray and optical flickering activity is strongly correlated, while short period pulsations are observed that occur at the same frequencies in both wavelength bands

Light

DEFF Research Database (Denmark)

Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

2004-01-01

This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

Opposite Distortions in Interval Timing Perception for Visual and Auditory Stimuli with Temporal Modulations.

Science.gov (United States)

Yuasa, Kenichi; Yotsumoto, Yuko

2015-01-01

When an object is presented visually and moves or flickers, the perception of its duration tends to be overestimated. Such an overestimation is called time dilation. Perceived time can also be distorted when a stimulus is presented aurally as an auditory flutter, but the mechanisms and their relationship to visual processing remains unclear. In the present study, we measured interval timing perception while modulating the temporal characteristics of visual and auditory stimuli, and investigated whether the interval times of visually and aurally presented objects shared a common mechanism. In these experiments, participants compared the durations of flickering or fluttering stimuli to standard stimuli, which were presented continuously. Perceived durations for auditory flutters were underestimated, while perceived durations of visual flickers were overestimated. When auditory flutters and visual flickers were presented simultaneously, these distortion effects were cancelled out. When auditory flutters were presented with a constantly presented visual stimulus, the interval timing perception of the visual stimulus was affected by the auditory flutters. These results indicate that interval timing perception is governed by independent mechanisms for visual and auditory processing, and that there are some interactions between the two processing systems.

Piezoelectric Non Linear Nanomechanical Temperature and Acceleration Insensitive Clocks (PENNTAC)

Science.gov (United States)

2016-07-01

relationship between the resonator Q and flicker noise when TED is largely mitigated , we measured a total of 25 resonators (11 full-anchor and 14...during this effort demonstrated the first fully integrated oven control system to mitigate the temperature effect on the reference clock. It showed...Reduction in AlN CMRs by Prolonged RF Excitation ............................................................ 13 2.6 Impact of Damping on Flicker

Cuttlefish Sepia officinalis Preferentially Respond to Bottom Rather than Side Stimuli When Not Allowed Adjacent to Tank Walls

Science.gov (United States)

2015-10-14

especially because cuttlefish are colorblind. Another possible concern is the flicker frequency of the plasma screens. The plasma screens used in... flicker . Given these reasons, we believe that the most reliable behavior with the least amount of human disturbance resulted from our use of the...0138690 October 14, 2015 15 / 18 Image analysis To mitigate the likelihood of autocorrelation, we used the two usable (i.e., non-blurry) images that were

Stakeholder Values and Perspectives when Implementing Led Lights on Navy Ships

Science.gov (United States)

2014-06-01

Human Factors in Lighting Freymiller, 2009, from Boyce, 2003) LEDs have no known cause of headaches due to flicker and the electronic magnetic...reoccurrence of dimming and flickering can reoccur. There should be further research conducted on how a headache affects the loss of productivity on...Walls, P. M. (2011, Dec). Eye disease resulting from increased use of fluorescent lighting as a climate change mitigation strategy. Retrieved from

Development of a Software-Defined Radar

Science.gov (United States)

2017-10-01

disrupt desired radar operation. The cognitive radar system discussed herein mitigates the effects of RFI by sensing and adapting the transmitted...present received data, and plot processed data. Top right: Calculates a “ flicker ” rate caused by an unknown issue where blank data are received due to...and plot processed data. Top right: Calculates a “ flicker ” rate caused by an unknown issue where blank data are received due to missed

Hardware Implementation of A Non-RLL Soft-decoding Beacon-based Visible Light Communication Receiver

OpenAIRE

Nguyen, Duc-Phuc; Le, Dinh-Dung; Tran, Thi-Hong; Huynh, Huu-Thuan; Nakashima, Yasuhiko

2018-01-01

Visible light communication (VLC)-based beacon systems, which usually transmit identification (ID) information in small-size data frames are applied widely in indoor localization applications. There is one fact that flicker of LED light should be avoid in any VLC systems. Current flicker mitigation solutions based on run-length limited (RLL) codes suffer from reduced code rates, or are limited to hard-decoding forward error correction (FEC) decoders. Recently, soft-decoding techniques of RLL-...

When a Standard Candle Flickers

DEFF Research Database (Denmark)

Wilson-Hodge, Colleen A; Cherry, Michael L; Case, Gary L

2011-01-01

-100 keV band with GBM, Swift /BAT, and INTEGRAL /IBIS. The pulsed flux measured with RXTE /PCA since 1999 is consistent with the pulsar spin-down, indicating that the observed changes are nebular. Correlated variations in the Crab Nebula flux on a ~ 3 year timescale are also seen independently...

Troxler Fading, Eye Movements, and Retinal Ganglion Cell Properties

Directory of Open Access Journals (Sweden)

Romain Bachy

2014-12-01

Full Text Available We present four movies demonstrating the effect of flicker and blur on the magnitude and speed of adaptation for foveal and peripheral vision along the three color axes that isolate retinal ganglion cells projecting to magno, parvo, and konio layers of the LGN. The demonstrations support the eye movement hypothesis for Troxler fading for brightness and color, and demonstrate the effects of flicker and blur on adaptation of each class of retinal ganglion cells.

A Personal Inertial Navigation System Based on Multiple Distributed, Nine-Degrees-Of-Freedom, Inertial Measurement Units

Science.gov (United States)

2016-12-01

the gyroscope to calculate position changes during the swing phase, it is important to identify and take steps to mitigate these major error types [11...holding a constant bias, flicker noise causes the error bias to randomly wander within a bounded area. For example, if the gyroscope was stationary and...39]. Flicker noise is the cause of error bias stability issues and is dominant at low frequencies where the power of its degrading effects can be

Mitigation of the voltage fluctuations using an efficient disturbance extraction technique

Energy Technology Data Exchange (ETDEWEB)

Elnady, Amr; Salama, M.M.A. [University of Waterloo, Electrical and Computer Engineering, 200 University Ave. West, Waterloo, Ont. (Canada N2L3G1)

2007-03-15

This paper introduces an efficient technique for extracting the disturbance signal of the voltage flicker. The proposed technique depends on the supervised state estimation that is controlled by the Widrow-Hoff delta rule. The extracted disturbance signal is employed for mitigating the cyclic voltage flicker by using series and parallel mitigating devices. The speed and accuracy of the proposed technique are verified by simulation results with EMTDC/PSCAD. In addition, experimental results are presented to prove the validity of the proposed algorithm. (author)

Numerical investigation of symmetry breaking and critical behavior of the acoustic streaming field in high-intensity discharge lamps

International Nuclear Information System (INIS)

Baumann, Bernd; Schwieger, Joerg; Wolff, Marcus; Manders, Freddy; Suijker, Jos

2015-01-01

For energy efficiency and material cost reduction it is preferred to drive high-intensity discharge lamps at frequencies of approximately 300 kHz. However, operating lamps at these high frequencies bears the risk of stimulating acoustic resonances inside the arc tube, which can result in low frequency light flicker and even lamp destruction. The acoustic streaming effect has been identified as the link between high frequency resonances and low frequency flicker. A highly coupled three-dimensional multiphysics model has been set up to calculate the acoustic streaming velocity field inside the arc tube of high-intensity discharge lamps. It has been found that the velocity field suffers a phase transition to an asymmetrical state at a critical acoustic streaming force. In certain respects the system behaves similar to a ferromagnet near the Curie point. It is discussed how the model allows to investigate the light flicker phenomenon. Concerning computer resources the procedure is considerably less demanding than a direct approach with a transient model. (paper)

Thermal undulations of quasi-spherical vesicles stabilized by gravity

DEFF Research Database (Denmark)

Henriksen, Jonas Rosager; Ipsen, John Hjorth

2002-01-01

) = DeltapgR(4)/k. The contributions from gravity are in most experimental situations small and thus negligible, but for values of go above a certain limit, the perturbational corrections must be included. Expressions for the relative error on the flicker spectrum have been worked out, so that it is possible...... to define the regime where gravity is negligible. An upper limit of go has also been identified, where the error in all modes of the flicker spectrum is significant due to distortion of the mean shape....

A bulk-controlled ring-VCO with 1/f-noise reduction for frequency ΔΣ modulator

DEFF Research Database (Denmark)

Tuan Vu, CAO; Wisland, Dag T.; Lande, Tor Sverre

The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub-threshol......The paper introduces a bulk-controlled ring-VCO with a tail transistor utilizing flicker-noise (1/f-noise) reduction techniques for a frequency-based DeltaSigma modulator (FDSM). This VCO converts an analog input voltage to phase information under various bias conditions ranging from sub...

Use of Biotechnological Devices in the Quantification of Psychophysiological Workload of Professional Chess Players.

Science.gov (United States)

Fuentes, Juan P; Villafaina, Santos; Collado-Mateo, Daniel; de la Vega, Ricardo; Gusi, Narcis; Clemente-Suárez, Vicente Javier

2018-01-19

Psychophysiological requirements of chess players are poorly understood, and periodization of training is often made without any empirical basis. For this reason, the aim of the present study was to investigate the psychophysiological response and quantify the player internal load during, and after playing a chess game. The participant was an elite 33 year-old male chess player ranked among the 300 best chess players in the world. Thus, cortical arousal by critical flicker fusion threshold, electroencephalogram by the theta Fz/alpha Pz ratio and autonomic modulation by heart rate variability were analyzed. Data revealed that cortical arousal by critical flicker fusion threshold and theta Fz/alpha Pz ratio increased and heart rate variability decreased during chess game. All these changes indicated that internal load increased during the chess game. In addition, pre-activation was detected in pre-game measure, suggesting that the prefrontal cortex might be preparatory activated. For these reasons, electroencephalogram, critical flicker fusion threshold and heart rate variability analysis may be highly applicable tools to control and monitor workload in chess player.

A biomechanical comparison in the lower limb and lumbar spine between a hit and drag flick in field hockey.

Science.gov (United States)

Ng, Leo; Rosalie, Simon M; Sherry, Dorianne; Loh, Wei Bing; Sjurseth, Andreas M; Iyengar, Shrikant; Wild, Catherine Y

2018-03-01

Research has revealed that field hockey drag flickers have greater odds of hip and lumbar injuries compared to non-drag flickers (DF). This study aimed to compare the biomechanics of a field hockey hit and a specialised field hockey drag flick. Eighteen male and seven female specialised hockey DF performed a hit and a drag flick in a motion analysis laboratory with an 18-camera three-dimensional motion analysis system and a calibrated multichannel force platform to examine differences in lower limb and lumbar kinematics and kinetics. Results revealed that drag flicks were performed with more of a forward lunge on the left lower limb resulting in significantly greater left ankle dorsiflexion, knee, hip and lumbar flexion (Pshit. Drag flicks were also performed with significantly greater lateral flexion (P hit. Differences in kinematics lead to greater shear, compression and tensile forces in multiple left lower limb and lumbar joints in the drag flick compared to the hit (P hit may have ramifications with respect to injury in field hockey drag flickers.

Modeling and Analysis of DIPPM: A New Modulation Scheme for Visible Light Communications

Directory of Open Access Journals (Sweden)

Sana Ullah Jan

2015-01-01

Full Text Available Visible Light Communication (VLC uses an Intensity-Modulation and Direct-Detection (IM/DD scheme to transmit data. However, the light source used in VLC systems is continuously switched on and off quickly, resulting in flickering. In addition, recent illumination systems include dimming support to allow users to dim the light sources to the desired level. Therefore, the modulation scheme for data transmission in VLC system must include flicker mitigation and dimming control capabilities. In this paper, the authors propose a Double Inverse Pulse Position Modulation (DIPPM scheme that minimizes flickering and supports a high level of dimming for the illumination sources in VLC systems. To form DIPPM, some changes are made in the symbol structure of the IPPM scheme, and a detailed explanation and mathematical model of DIPPM are given in this paper. Furthermore, both analytical and simulation results for the error performance of 2-DIPPM are compared with the performance of VPPM. Also, the communication performance of DIPPM is analyzed in terms of the normalized required power.

Asynchrony Detection in Amblyopes

Directory of Open Access Journals (Sweden)

Pi-Chun Huang

2012-10-01

Full Text Available Amblyopia is a developmental abnormality of visual cortex. Although amblyopes experience perceptual deficits in spatial vision tasks, they have less temporal sensitivity loss. We investigated whether their temporal synchrony sensitivity is impaired. In experiment 1, four Gaussian blobs, located at the top, bottom, left, and right of a presentation screen, were flickering in 3 Hz and one of them was flickering in out-of-phase fashion in time. Participants needed to tell which blob was different from the other three and contrast threshold of the blobs was measured to determine the synchrony detection threshold. We found the thresholds were not correlated with the contrast thresholds for detecting the flickering blobs, suggesting synchrony detection and temporal detection threshold are processed by different mechanisms. In experiment 2, synchrony thresholds were measured as participants' ability to tell if one of the four high contrast Gaussian blobs was flickering asynchronously in time. Three temporal frequencies (1, 2, and 3 Hz and two element separations (1.25 and 5 deg were compared. We found that the amblyopic group exhibited a deficit only for the 1.25 deg element separation in amblyopic eye but was normal for the other configurations compared to controlled participants. It suggests amblyopes have deficits in temporal processing but only for foveal vision. We also found the sensitivity for the non-strabismic anismetropia group is reduced for all three temporal frequencies whereas for the strabismic anisometropia group it was reduced at 3Hz only, suggesting the impairment in temporal synchrony might be different for different types of amblyopia.

Mechanisms of video-game epilepsy.

Science.gov (United States)

Fylan, F; Harding, G F; Edson, A S; Webb, R M

1999-01-01

We aimed to elucidate the mechanisms underlying video-game epilepsy by comparing the flicker- and spatial-frequency ranges over which photic and pattern stimulation elicited photoparoxysmal responses in two different populations: (a) 25 patients with a history of seizures experienced while playing video games; and (b) 25 age- and medication-matched controls with a history of photosensitive epilepsy, but no history of video-game seizures. Abnormality ranges were determined by measuring photoparoxysmal EEG abnormalities as a function of the flicker frequency of patterned and diffuse intermittent photic stimulation (IPS) and the spatial frequency of patterns on a raster display. There was no significant difference between the groups in respect of the abnormality ranges elicited by patterned or diffuse IPS or by spatial patterns. When the groups were compared at one specific IPS frequency (-50 Hz), however, the flicker frequency of European television displays, the video-game patients were significantly more likely to be sensitive. The results suggest that video-game seizures are a manifestation of photosensitive epilepsy. The increased sensitivity of video-game patients to IPS at 50 Hz indicates that display flicker may underlie video-game seizures. The similarity in photic- and pattern-stimulation ranges over which abnormalities are elicited in video-game patients and controls suggests that all patients with photosensitive epilepsy may be predisposed toward video-game-induced seizures. Photosensitivity screening should therefore include assessment by using both IPS at 50 Hz and patterns displayed on a television or monitor with a 50-Hz frame rate.

Investigation of Noises in GPS Time Series: Case Study on Epn Weekly Solutions

Science.gov (United States)

Klos, Anna; Bogusz, Janusz; Figurski, Mariusz; Kosek, Wieslaw; Gruszczynski, Maciej

2014-05-01

The noises in GPS time series are stated to be described the best by the combination of white (Gaussian) and power-law processes. They are mainly the effect of mismodelled satellite orbits, Earth orientation parameters, atmospheric effects, antennae phase centre effects, or of monument instability. Due to the fact, that velocities of permanent stations define the kinematic reference frame, they have to fulfil the requirement of being stable at 0.1 mm/yr. The previously performed researches showed, that the wrong assumption of noise model leads to the underestimation of velocities and their uncertainties from 2 up to even 11, especially in the Up direction. This presentation focuses on more than 200 EPN (EUREF Permanent Network) stations from the area of Europe with various monument types (concrete pillars, buildings, metal masts, with or without domes, placed on the ground or on the rock) and coordinates of weekly changes (GPS weeks 0834-1459). The topocentric components (North, East, Up) in ITRF2005 which come from the EPN Re-Processing made by the Military University of Technology Local Analysis Centre (MUT LAC) were processed with Maximum Likelihood Estimation (MLE) using CATS software. We have assumed the existence of few combinations of noise models (these are: white, flicker and random walk noise with integer spectral indices and power-law noise models with fractional spectral indices) and investigated which of them EPN weekly time series are likely to follow. The results show, that noises in GPS time series are described the best by the combination of white and flicker noise model. It is strictly related to the so-called common mode error (CME) that is spatially correlated error being one of the dominant error source in GPS solutions. We have assumed CME as spatially uniform, what was a good approximation for stations located hundreds of kilometres one to another. Its removal with spatial filtering reduces the amplitudes of white and flicker noise by a

Frequency-dependent tACS modulation of BOLD signal during rhythmic visual stimulation.

Science.gov (United States)

Chai, Yuhui; Sheng, Jingwei; Bandettini, Peter A; Gao, Jia-Hong

2018-05-01

Transcranial alternating current stimulation (tACS) has emerged as a promising tool for modulating cortical oscillations. In previous electroencephalogram (EEG) studies, tACS has been found to modulate brain oscillatory activity in a frequency-specific manner. However, the spatial distribution and hemodynamic response for this modulation remains poorly understood. Functional magnetic resonance imaging (fMRI) has the advantage of measuring neuronal activity in regions not only below the tACS electrodes but also across the whole brain with high spatial resolution. Here, we measured fMRI signal while applying tACS to modulate rhythmic visual activity. During fMRI acquisition, tACS at different frequencies (4, 8, 16, and 32 Hz) was applied along with visual flicker stimulation at 8 and 16 Hz. We analyzed the blood-oxygen-level-dependent (BOLD) signal difference between tACS-ON vs tACS-OFF, and different frequency combinations (e.g., 4 Hz tACS, 8 Hz flicker vs 8 Hz tACS, 8 Hz flicker). We observed significant tACS modulation effects on BOLD responses when the tACS frequency matched the visual flicker frequency or the second harmonic frequency. The main effects were predominantly seen in regions that were activated by the visual task and targeted by the tACS current distribution. These findings bridge different scientific domains of tACS research and demonstrate that fMRI could localize the tACS effect on stimulus-induced brain rhythms, which could lead to a new approach for understanding the high-level cognitive process shaped by the ongoing oscillatory signal. © 2018 Wiley Periodicals, Inc.

Noise frame duration, masking potency and whiteness of temporal noise.

Science.gov (United States)

Kukkonen, Heljä; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antti

2002-09-01

Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. Contrast energy thresholds (E(th)) were measured for flicker at 1.25 to 20 Hz in strong, purely temporal (spatially uniform), additive, external noise. The masking power of white external noise, characterized by its spectral density at zero frequency N0, increases with the duration of the noise frame. For short noise frame durations, E(th) increased in direct proportion to N0, keeping the nominal signal-to-noise ratio [SNR = (E(th)/N0)(0.5)] constant at threshold. The masking effect thus increased with the duration of the noise frame and the noise mimicked white noise. When noise frame duration and N0 increased further, the nominal SNR at threshold started to decrease, indicating that noise no longer mimicked white noise. The minimum number of noise frames per flicker cycle needed to mimic white noise decreased with increasing flicker frequency from 8.3 at 1.25 Hz to 1.6 at 20 Hz. The critical high-frequency cutoff of detection-limiting temporal noise in terms of noise frames per signal cycle depends on the temporal frequency of the signal. This is opposite to the situation in the spatial domain and must be taken into consideration when temporal signals are masked with temporal noise.

Alternative Line Coding Scheme with Fixed Dimming for Visible Light Communication

Science.gov (United States)

Niaz, M. T.; Imdad, F.; Kim, H. S.

2017-01-01

An alternative line coding scheme called fixed-dimming on/off keying (FD-OOK) is proposed for visible-light communication (VLC). FD-OOK reduces the flickering caused by a VLC transmitter and can maintain a 50% dimming level. Simple encoder and decoder are proposed which generates codes where the number of bits representing one is same as the number of bits representing zero. By keeping the number of ones and zeros equal the change in the brightness of lighting may be minimized and kept constant at 50%, thereby reducing the flickering in VLC. The performance of FD-OOK is analysed with two parameters: the spectral efficiency and power requirement.

Influence of the operating parameters and of the sample introduction system on time correlation of line intensities using an axially viewed CCD-based ICP-AES system

Energy Technology Data Exchange (ETDEWEB)

Grotti, Marco, E-mail: grotti@chimica.unige.i [Dipartimento di Chimica e Chimica Industriale, Via Dodecaneso 31, 16146 Genova (Italy); Todoli, Jose Luis [Departamento de Quimica Analitica, Nutricion y Bromatologia, Universidad de Alicante, 03080, Alicante (Spain); Mermet, Jean Michel [Spectroscopy Forever, 01390 Tramoyes (France)

2010-02-15

The influence of the acquisition and operating parameters on time correlation between emission line intensities was investigated using axially viewed inductively coupled plasma-multichannel-based emission spectrometry and various sample introduction systems. It was found that to obtain flicker-noise limited signals, necessary to compensate for time-correlated signal fluctuations by internal standardization, the flicker-noise magnitude of the sample introduction system, the integration time and the emission line intensity had to be considered. The highest correlation between lines was observed for ultrasonic nebulization with desolvatation, the noisiest system among those considered, for which the contribution of the uncorrelated shot-noise was negligible. In contrast, for sample introduction systems characterized by lower flicker-noise levels, shot-noise led to high, non-correlated RSD values, making the internal standard method to be much less efficient. To minimize shot-noise, time correlation was improved by increasing the emission line intensities and the integration time. Improvement in repeatability did not depend only on time correlation, but also on the ratio between the relative standard deviations of the analytical and reference lines. The best signal compensation was obtained when RSD values of the reference and analytical lines were similar, which is usually obtained when the system is flicker-noise limited, while departure from similarity can lead to a degradation of repeatability when using the internal standard method. Moreover, the use of so-called robust plasma conditions, i.e. a high power (1500 W) along with a low carrier gas flow rate (0.8 L/min) improved also the compensation. Finally, high correlation and consequent improvement in repeatability by internal standardization was observed also in the presence of complex matrices (sediment and soil samples), although a matrix-induced degradation of the correlation between lines was generally

Condition of organ of vision and free radical process parameters in liquidators of the Chernobyl accident

International Nuclear Information System (INIS)

Sosnovsky, S.; Danilicnev, V.; Nikiforov, A.; Zybina, N.; Nesteruk, L.

1997-01-01

84 liquidators of consequences of Chernobyl APS accident from the age of 28 to 58 were examined. The control group was made with 22 men from the age of 28 to 52. A certain increase of infringement of a transparency of lens without typical attributes of radiating cataract is revealed in the experimental group. Electrophysiological investigation (EPI) shows a certain reduction of amplitude of a wave ''a'' of macular electroretinogram (ERG) on green stimulus, amplitude of a main component and lengthening of an interpeak time interval of flicker ERG 10 Hz is revealed. These changes indicate the tendency to reduction of functional activity of a retina (first of all at a level of photoreceptors) in paramacular and in a smaller degree in peripheral zones among liquidators. The parameters of contrast sensitivity are definitely reduced in the experimental group for all stimuli on all spatial frequencies. Luminous and colour sensitivity to stimuli of different colour in the experimental group is definitely reduced in all central field of sight, but in paracentral zone the degree of reduction is higher. We investigated the parameters of oxidative stress in both groups. Definite increase of production of the reactive oxygen species and disbalance of a glutathione link of antioxidant protection are revealed. Authentic correlation dependences are revealed: moderate direct correlation - between a level of glutathione reductase and amplitude of a main component of flicker ERG 10 Hz, between a level of oxidized glutathione and interpeak time interval of flicker ERG 10 Hz, inverse correlation - between the level of oxidized glutathione and amplitude of a main component of flicker ERG 10 Hz. In view of large spontaneous activity of free radical processes in a retina in norm the received results can explain revealed changes of an organ of vision. (author)

Condition of organ of vision and free radical process parameters in liquidators of the Chernobyl accident

Energy Technology Data Exchange (ETDEWEB)

Sosnovsky, S; Danilicnev, V [Military Medical Academy, Saint-Petersburg (Russian Federation); Nikiforov, A; Zybina, N [All-Russian Center of Emergency and Radiation Medicine, Saint-Petersburg (Russian Federation); Nesteruk, L [Helmholtz Inst. of Eyes Diseases, Moscow (Russian Federation)

1997-11-01

84 liquidators of consequences of Chernobyl APS accident from the age of 28 to 58 were examined. The control group was made with 22 men from the age of 28 to 52. A certain increase of infringement of a transparency of lens without typical attributes of radiating cataract is revealed in the experimental group. Electrophysiological investigation (EPI) shows a certain reduction of amplitude of a wave ``a`` of macular electroretinogram (ERG) on green stimulus, amplitude of a main component and lengthening of an interpeak time interval of flicker ERG 10 Hz is revealed. These changes indicate the tendency to reduction of functional activity of a retina (first of all at a level of photoreceptors) in paramacular and in a smaller degree in peripheral zones among liquidators. The parameters of contrast sensitivity are definitely reduced in the experimental group for all stimuli on all spatial frequencies. Luminous and colour sensitivity to stimuli of different colour in the experimental group is definitely reduced in all central field of sight, but in paracentral zone the degree of reduction is higher. We investigated the parameters of oxidative stress in both groups. Definite increase of production of the reactive oxygen species and disbalance of a glutathione link of antioxidant protection are revealed. Authentic correlation dependences are revealed: moderate direct correlation - between a level of glutathione reductase and amplitude of a main component of flicker ERG 10 Hz, between a level of oxidized glutathione and interpeak time interval of flicker ERG 10 Hz, inverse correlation - between the level of oxidized glutathione and amplitude of a main component of flicker ERG 10 Hz. In view of large spontaneous activity of free radical processes in a retina in norm the received results can explain revealed changes of an organ of vision. (author). 5 refs.

Some Motivational Properties of Sensory Stimulation in Psychotic Children

Science.gov (United States)

Rincover, Arnold; And Others

1977-01-01

This experiment assessed the reinforcing properties of sensory stimulation for autistic children using three different types of sensory stimulation: music, visual flickering, and visual movement. (SB)

Monitor quality and its importance in a picture archiving and communications system display workstation

International Nuclear Information System (INIS)

Dawood, R.M.; Todd-Prokropek, A.; Craig, J.O.M.C.; Highman, J.H.; Glass, H.D.

1988-01-01

Trials have compared image quality using receiver operating characteristic (ROC) curves for different digitization resolution, particularly on hard copy. Resolution required for such systems is critical. Monitor quality significantly affects results of such studies. Several ''high-quality'' monitors were tested for gray level uniformity, flicker, resolution, stationarity (including distortion), jitter, and stability with time. An ROC study has demonstrated that such errors, on one commercially available system, were large enough to degrade image display at both 1k x 1k and 2k x 2k matrix sizes. Flicker was very disturbing with difficult images. Greater attention to these factors is required in designing (and evaluating) picture archiving and communication system work stations

Sebaceous carcinoma. Presenting a case

International Nuclear Information System (INIS)

Plaza, Jaime; Salinas, Ana; Cabrera, Raul; Vargas, Martha; Caicedo, Eduardo

2002-01-01

Patient of feminine sex of 65 years of age with tumor of approximately 1.5 cm of diameter, located in the right palpebral region, being put under ample exeresis of a tumor more pastia, whose anatomopathology result revealed sebaceous carcinoma with free edges. This is a rare malignant carcinoma that originates in perioculars sebaceous glands like the glands of Meibomio that affects the superior flicker. Clinically it appears like a small nodule, of small growth and its diagnose is based on a high degree of suspicion in any chronic process of the flicker. The selection processing is the surgery, the x-ray, radiotherapy is useful in the postoperating attention and like palliative therapy. (The author)

Selective attention to task-irrelevant emotional distractors is unaffected by the perceptual load associated with a foreground task.

Science.gov (United States)

Hindi Attar, Catherine; Müller, Matthias M

2012-01-01

A number of studies have shown that emotionally arousing stimuli are preferentially processed in the human brain. Whether or not this preference persists under increased perceptual load associated with a task at hand remains an open question. Here we manipulated two possible determinants of the attentional selection process, perceptual load associated with a foreground task and the emotional valence of concurrently presented task-irrelevant distractors. As a direct measure of sustained attentional resource allocation in early visual cortex we used steady-state visual evoked potentials (SSVEPs) elicited by distinct flicker frequencies of task and distractor stimuli. Subjects either performed a detection (low load) or discrimination (high load) task at a centrally presented symbol stream that flickered at 8.6 Hz while task-irrelevant neutral or unpleasant pictures from the International Affective Picture System (IAPS) flickered at a frequency of 12 Hz in the background of the stream. As reflected in target detection rates and SSVEP amplitudes to both task and distractor stimuli, unpleasant relative to neutral background pictures more strongly withdrew processing resources from the foreground task. Importantly, this finding was unaffected by the factor 'load' which turned out to be a weak modulator of attentional processing in human visual cortex.

Selective attention to task-irrelevant emotional distractors is unaffected by the perceptual load associated with a foreground task.

Directory of Open Access Journals (Sweden)

Catherine Hindi Attar

Full Text Available A number of studies have shown that emotionally arousing stimuli are preferentially processed in the human brain. Whether or not this preference persists under increased perceptual load associated with a task at hand remains an open question. Here we manipulated two possible determinants of the attentional selection process, perceptual load associated with a foreground task and the emotional valence of concurrently presented task-irrelevant distractors. As a direct measure of sustained attentional resource allocation in early visual cortex we used steady-state visual evoked potentials (SSVEPs elicited by distinct flicker frequencies of task and distractor stimuli. Subjects either performed a detection (low load or discrimination (high load task at a centrally presented symbol stream that flickered at 8.6 Hz while task-irrelevant neutral or unpleasant pictures from the International Affective Picture System (IAPS flickered at a frequency of 12 Hz in the background of the stream. As reflected in target detection rates and SSVEP amplitudes to both task and distractor stimuli, unpleasant relative to neutral background pictures more strongly withdrew processing resources from the foreground task. Importantly, this finding was unaffected by the factor 'load' which turned out to be a weak modulator of attentional processing in human visual cortex.

Discovery of Fast, Large-amplitude Optical Variability of V648 Car (=SS73-17)

Science.gov (United States)

Angeloni, R.; Di Mille, F.; Ferreira Lopes, C. E.; Masetti, N.

2012-09-01

We report on the discovery of large-amplitude flickering from V648 Car (= SS73-17), a poorly studied object listed among the very few hard X-ray-emitting symbiotic stars. We performed millimagnitude precision optical photometry with the Swope Telescope at the Las Campanas Observatory, Chile, and found that V648 Car shows large U-band variability over timescales of minutes. To our knowledge, it exhibits some of the largest flickering of a symbiotic star ever reported. Our finding supports the hypothesis that symbiotic white dwarfs producing hard X-rays are predominantly powered by accretion, rather than quasi-steady nuclear burning, and have masses close to the Chandrasekhar limit. No significant periodicity is evident from the flickering light curve. The All Sky Automated Survey long-term V light curve suggests the presence of a tidally distorted giant accreting via Roche lobe overflow, and a binary period of ~520 days. On the basis of the outstanding physical properties of V648 Car as hinted at by its fast and long-term optical variability, as well as by its nature as a hard X-ray emitter, we therefore call for simultaneous follow-up observations in different bands, ideally combined with time-resolved optical spectroscopy.

Switches of stimulus tagging frequencies interact with the conflict-driven control of selective attention, but not with inhibitory control.

Science.gov (United States)

Scherbaum, Stefan; Frisch, Simon; Dshemuchadse, Maja

2016-01-01

Selective attention and its adaptation by cognitive control processes are considered a core aspect of goal-directed action. Often, selective attention is studied behaviorally with conflict tasks, but an emerging neuroscientific method for the study of selective attention is EEG frequency tagging. It applies different flicker frequencies to the stimuli of interest eliciting steady state visual evoked potentials (SSVEPs) in the EEG. These oscillating SSVEPs in the EEG allow tracing the allocation of selective attention to each tagged stimulus continuously over time. The present behavioral investigation points to an important caveat of using tagging frequencies: The flicker of stimuli not only produces a useful neuroscientific marker of selective attention, but interacts with the adaptation of selective attention itself. Our results indicate that RT patterns of adaptation after response conflict (so-called conflict adaptation) are reversed when flicker frequencies switch at once. However, this effect of frequency switches is specific to the adaptation by conflict-driven control processes, since we find no effects of frequency switches on inhibitory control processes after no-go trials. We discuss the theoretical implications of this finding and propose precautions that should be taken into account when studying conflict adaptation using frequency tagging in order to control for the described confounds. Copyright © 2015 Elsevier B.V. All rights reserved.

DISCOVERY OF FAST, LARGE-AMPLITUDE OPTICAL VARIABILITY OF V648 Car (=SS73-17)

International Nuclear Information System (INIS)

Angeloni, R.; Di Mille, F.; Ferreira Lopes, C. E.; Masetti, N.

2012-01-01

We report on the discovery of large-amplitude flickering from V648 Car (= SS73-17), a poorly studied object listed among the very few hard X-ray-emitting symbiotic stars. We performed millimagnitude precision optical photometry with the Swope Telescope at the Las Campanas Observatory, Chile, and found that V648 Car shows large U-band variability over timescales of minutes. To our knowledge, it exhibits some of the largest flickering of a symbiotic star ever reported. Our finding supports the hypothesis that symbiotic white dwarfs producing hard X-rays are predominantly powered by accretion, rather than quasi-steady nuclear burning, and have masses close to the Chandrasekhar limit. No significant periodicity is evident from the flickering light curve. The All Sky Automated Survey long-term V light curve suggests the presence of a tidally distorted giant accreting via Roche lobe overflow, and a binary period of ∼520 days. On the basis of the outstanding physical properties of V648 Car as hinted at by its fast and long-term optical variability, as well as by its nature as a hard X-ray emitter, we therefore call for simultaneous follow-up observations in different bands, ideally combined with time-resolved optical spectroscopy.

75 FR 922 - Notification and Reporting of Aircraft Accidents or Incidents and Overdue Aircraft, and...

Science.gov (United States)

2010-01-07

... hardware or software problems. The NTSB considered this potential meaning of ``flickering'' when it originally defined the language of this section. After reviewing this concept, the NTSB has decided against...

Resource partitioning among woodpeckers in northeastern Oregon.

Science.gov (United States)

Bull Evelyn L.; Steven R. Peterson; Jack Ward. Thomas

1986-01-01

Eight species of woodpeckers coexist in conifer forests in northeastern Oregon: northern flicker (Colaptes auratus); yellow-bellied (Sphyrapicus varius) and Williamson's (S. thyroideus) sapsuckers; and pileated (Dryocopus pileatus), hairy (Picoides villosus),...

Decoding of top-down cognitive processing for SSVEP-controlled BMI

Science.gov (United States)

Min, Byoung-Kyong; Dähne, Sven; Ahn, Min-Hee; Noh, Yung-Kyun; Müller, Klaus-Robert

2016-11-01

We present a fast and accurate non-invasive brain-machine interface (BMI) based on demodulating steady-state visual evoked potentials (SSVEPs) in electroencephalography (EEG). Our study reports an SSVEP-BMI that, for the first time, decodes primarily based on top-down and not bottom-up visual information processing. The experimental setup presents a grid-shaped flickering line array that the participants observe while intentionally attending to a subset of flickering lines representing the shape of a letter. While the flickering pixels stimulate the participant’s visual cortex uniformly with equal probability, the participant’s intention groups the strokes and thus perceives a ‘letter Gestalt’. We observed decoding accuracy of 35.81% (up to 65.83%) with a regularized linear discriminant analysis; on average 2.05-fold, and up to 3.77-fold greater than chance levels in multi-class classification. Compared to the EEG signals, an electrooculogram (EOG) did not significantly contribute to decoding accuracies. Further analysis reveals that the top-down SSVEP paradigm shows the most focalised activation pattern around occipital visual areas; Granger causality analysis consistently revealed prefrontal top-down control over early visual processing. Taken together, the present paradigm provides the first neurophysiological evidence for the top-down SSVEP BMI paradigm, which potentially enables multi-class intentional control of EEG-BMIs without using gaze-shifting.

Photometric Evidence for a Disc-Jet Connection in CH Cygni

Science.gov (United States)

Sokoloski, J. L.; Kenyon, S. J.

2001-12-01

We describe observations of the rapid optical variations of the symbiotic star CH Cygni on 12 nights between 1997 and 1999. The B-band differential light curves reveal an incredible diversity of flickering behavior, from large-amplitude (up to 0.5 mag) variations with a power-law power spectrum, to lower amplitude (0.1 mag) variations with both power-law and non-power-law power spectra, to the complete absence of rapid variations down to a level of mmag. The series of light curves from observations in 1997/1998 exhibit an evolution from smooth, low-amplitude variations, to high-amplitude flickering with power at all measurable time scales. This evolution may be showing us the re-creation of the inner accretion disc after its disruption in association with the jet that was produced in early 1997 (Karovska et al. 1998). We do not find any evidence for quasi-periodic oscillations in the power spectra of individual light curves, and we believe the instances in which flickering completely disappeared coincide with eclipse of the white dwarf and accretion disc. We discuss the implications of our results for magnetic propeller models of this system, as well as compare CH Cygni to other systems where disc-jet connections have been proposed, such as the Galactic microquasar GRS 1915+105. This work was funded in part by NSF grant INT-9902665 to J.L.S.

Pop / Tõnu Kaalep

Index Scriptorium Estoniae

Kaalep, Tõnu, 1966-2018

2002-01-01

Heliplaatidest Roger Waters "The Flickering Flame: The Solo Years Vol 1". Jah Wobble's Solaris "Live in Concert". Andreas Moras / Igor Cavalera / Andreas Kisser "No Coracao Des Deuses - Soundtrack". Ed Case "Ed's Guest List"

Top Five Large-Scale Solar Myths | State, Local, and Tribal Governments |

Science.gov (United States)

shadow on neighboring properties, cause light flicker, or have the same visual impact as wind farms), the . Some communities have opted for mitigation measures to reduce visual impacts of solar farms through the

Response to acoustic forcing of laminar coflow jet diffusion flames

KAUST Repository

Chrystie, Robin; Chung, Suk-Ho

2014-01-01

Toward the goal of understanding and controlling instability in combustion systems, we present a fundamental characterization of the interaction of the buoyancy-induced instability in flickering flames with forced excitation of fuel supply. Laminar

Convection in Cool Stars, as Seen Through Kepler's Eyes

Science.gov (United States)

Bastien, Fabienne A.

2015-01-01

Stellar surface processes represent a fundamental limit to the detection of extrasolar planets with the currently most heavily-used techniques. As such, considerable effort has gone into trying to mitigate the impact of these processes on planet detection, with most studies focusing on magnetic spots. Meanwhile, high-precision photometric planet surveys like CoRoT and Kepler have unveiled a wide variety of stellar variability at previously inaccessible levels. We demonstrate that these newly revealed variations are not solely magnetically driven but also trace surface convection through light curve ``flicker.'' We show that ``flicker'' not only yields a simple measurement of surface gravity with a precision of ˜0.1 dex, but it may also improve our knowledge of planet properties, enhance radial velocity planet detection and discovery, and provide new insights into stellar evolution.

Fatiga del sistema nervioso después de una prueba de contrarreloj de 30’ en cicloergómetro en ciclistas jóvenes Fatigue of nervous system after a test trial of 30 'on a cycleergometer in young cyclists

Directory of Open Access Journals (Sweden)

V. J. Clemente

2010-12-01

Full Text Available

Varios autores han estudiado la influencia del ejercicio sobre el sistema nervioso y el funcionamiento cognitivo en sujetos desentrenados y ante diferentes estímulos de ejercicio mediante los Umbrales Flicker Fusion (UFF. Aunque el efecto en el sistema nervioso central (SNC de estímulos máximos aeróbicos no está muy estudiado. El presente trabajo de investigación pretende estudiar los cambios en los UFF antes y después de realizar una contrareloj de 30’ en cicloergómetro, como medio para valorar la fatiga del SNC.
La muestra la componen 9 sujetos varones (72.1±5.59 Kg., 180.3±6.43 cm, 17.4±0.7 años, 14.1±2.69 % grasa, 22.2±1.65 Kg./m2 de IMC, VO2max [ml/ Kg./min.] 83.24±4.06, VO2max [l]: 5.95±0.53.
Se realizó una prueba de 30’ máximo en cicloergómetro. Previo al test y al finalizar éste, se realizaron las mediciones de los UFF ascendente, descendente y clásico, criterio subjetivo y sensibilidad sensorial. Cada sujeto realizó el test  de UFF en tres ocasiones obteniéndose un valor promedio.
Los resultados muestran cómo los UFF aumentan después de la prueba. Con estos resultados podemos concluir que una prueba máxima de 30’ en cicloergómetro no parece que generen fatiga en el Sistema Nervioso Central medida con el sistema Flicker Fusion, al no disminuir los distintos UFF.
Palabras clave:Sistema nervioso central, Fatiga, Umbrales Flicker Fusion, cicloergómetro

Distributed amplified ultra-stable signal quartz oscillator based

Czech Academy of Sciences Publication Activity Database

Salzenstein, P.; Cholley, N.; Kuna, Alexander; Abbé, P.; Lardet-Vieudrin, F.; Šojdr, Ludvík; Chauvin, J.

2012-01-01

Roč. 45, č. 7 (2012), s. 1937-1939 ISSN 0263-2241 Institutional support: RVO:67985882 Keywords : Time-frequency * Modulation * Flicker frequency Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.130, year: 2012

Various categories of changes in the inducement of change blindness

Czech Academy of Sciences Publication Activity Database

Porubanová-Norquist, M.; Šikl, Radovan

2013-01-01

Roč. 55, č. 2 (2013), s. 83-94 ISSN 0039-3320 Institutional support: RVO:68081740 Keywords : change blindness * scene perception * flicker paradigm * attention allocation * attention Subject RIV: AN - Psychology Impact factor: 0.414, year: 2013

Plaadid / Margus Kiis

Index Scriptorium Estoniae

Kiis, Margus

2002-01-01

Uutest plaatidest Nightlight Dou "La Fiesta Del Sol", Yves Montand "Ses Plus Grands Succes", Natalia Oreiro "Tu veneno", Daishin Kashimoto "Passionata", Mike Oldfield "Tres Lunas", Ali G Indiahouse "Da Soundtrack", Ronan Keating "Destination", Roger Waters "Flickering Flame"

Numerical and Experimental Study on Negative Buoyance Induced Vortices in N-Butane Jet Flames

KAUST Repository

Xiong, Yuan; Cha, Min; Chung, Suk-Ho

2015-01-01

Near nozzle flow field in flickering n-butane diffusion jet flames was investigated with a special focus on transient flow patterns of negative buoyance induced vortices. The flow structures were obtained through Mie scattering imaging with seed

Unidirectional visible light communication and illumination with LEDs

NARCIS (Netherlands)

Li, S.; Pandharipande, A.; Willems, F.M.J.

2016-01-01

Visible light communication (VLC) with light emitting diodes (LEDs) has attracted interest for interactive and networked lighting control, and consumer infotainment applications. In this paper, we propose an LED system for jointly achieving unidirectional VLC while providing flicker-free

Studies of FAUNA at Eglin Air Force Base

Science.gov (United States)

2006-07-01

occasionally resulted in fires that were hot enough to kill mature pines, including the old growth pines upon which RCWs depend for cavity excavation...cardinalis NOCA Northern flicker* Colaptes auratus NOFL Northern mockingbird Mimus polyglottos NOMO Northern rough-winged swallow Stelgidopteryx

Macular pigment optical density is related to serum lutein in retinitis pigmentosa

Science.gov (United States)

Purpose: To determine whether macular pigment optical density (MPOD) is related to the degree of cystoid macular edema (CME) in patients with retinitis pigmentosa. Methods: We measured MPOD with heterochromatic flicker photometry and central foveal retinal thickness with optical coherence tomography...

Television picture signal processing

NARCIS (Netherlands)

1998-01-01

Field or frame memories are often used in television receivers for video signal processing functions, such as noise reduction and/or flicker reduction. Television receivers also have graphic features such as teletext, menu-driven control systems, multilingual subtitling, an electronic TV-Guide, etc.

Simultaneous IR and optical light curves of 2A0311-227

International Nuclear Information System (INIS)

Bailey, J.; Hough, J.H.; Axon, D.J.

1983-01-01

It is reported that the optical and IR flickering of the AM Herculis type binary 2A0311 - 227 are highly correlated indicating that in this object the dominant source of cyclotron radiation at both wavelengths is the same accretion column. (U.K.)

A Fully Integrated Discrete-Time Superheterodyne Receiver

NARCIS (Netherlands)

Tohidian, M.; Madadi, I.; Staszewski, R.B.

2017-01-01

The zero/low intermediate frequency (IF) receiver (RX) architecture has enabled full CMOS integration. As the technology scales and wireless standards become ever more challenging, the issues related to time-varying dc offsets, the second-order nonlinearity, and flicker noise become more critical.

CHD2 variants are a risk factor for photosensitivity in epilepsy

DEFF Research Database (Denmark)

Galizia, Elizabeth C.; Myers, Candace T.; Leu, Costin

2015-01-01

Photosensitivity is a heritable abnormal cortical response to flickering light, manifesting as particular electroencephalographic changes, with or without seizures. Photosensitivity is prominent in a very rare epileptic encephalopathy due to de novo CHD2 mutations, but is also seen in epileptic e...

Older driver failures of attention at intersections: using change blindness methods to assess turn decision accuracy.

Science.gov (United States)

Caird, Jeff K; Edwards, Christopher J; Creaser, Janet I; Horrey, William J

2005-01-01

A modified version of the flicker technique to induce change blindness was used to examine the effects of time constraints on decision-making accuracy at intersections on a total of 62 young (18-25 years), middle-aged (26-64 years), young-old (65-73 years), and old-old (74+ years) drivers. Thirty-six intersection photographs were manipulated so that one object (i.e., pedestrian, vehicle, sign, or traffic control device) in the scene would change when the images were alternated for either 5 or 8 s using the modified flicker method. Young and middle-aged drivers made significantly more correct decisions than did young-old and old-old drivers. Logistic regression analysis of the data indicated that age and/or time were significant predictors of decision performance in 14 of the 36 intersections. Actual or potential applications of this research include driving assessment and crash investigation.

DAC to Mitigate the Effect of Periodic Disturbances on Drive Train using Collective Pitch for Variable Speed Wind Turbine

DEFF Research Database (Denmark)

Imran, Raja Muhammad; Hussain, Dil Muhammad Akbar; Soltani, Mohsen

2015-01-01

scheme to mitigate the effect of 3p flicker on drive train. 5MW wind turbine of the National Renewable Laboratories (NREL) is used as research object and results are simulated in MATLAB/Simulink. We designed the controller based on linearized model of the wind turbine generated for above rated wind speed...... and then tested its performance on the nonlinear model of wind turbine. We have shown a comparison of the results for proportional-integral(PI) and proposed DAC controller tested on nonlinear model of wind turbine. Result shows that our proposed controller shows better mitigation of flicker generated due to 3p......DAC is a linear control technique used to mitigate the effect of disturbance on the plant. It is a superposition of full state feedback and disturbance feedback. This paper presents a control technique based on Disturbance Accommodation Control (DAC) to reduce fatigue on drive train generated...

Functional imaging of hemodynamic stimulus response in the rat retina with ultrahigh-speed spectral / Fourier domain OCT

Science.gov (United States)

Choi, WooJhon; Baumann, Bernhard; Clermont, Allen C.; Feener, Edward P.; Boas, David A.; Fujimoto, James G.

2013-03-01

Measuring retinal hemodynamics in response to flicker stimulus is important for investigating pathophysiology in small animal models of diabetic retinopathy, because a reduction in the hyperemic response is thought to be one of the earliest changes in diabetic retinopathy. In this study, we investigated functional imaging of retinal hemodynamics in response to flicker stimulus in the rat retina using an ultrahigh speed spectral / Fourier domain OCT system at 840nm with an axial scan rate of 244kHz. At 244kHz the nominal axial velocity range that could be measured without phase wrapping was +/-37.7mm/s. Pulsatile total retinal arterial blood flow as a function of time was measured using an en face Doppler approach where a 200μm × 200μm area centered at the central retinal artery was repeatedly raster scanned at a volume acquisition rate of 55Hz. Three-dimensional capillary imaging was performed using speckle decorrelation which has minimal angle dependency compared to other angiography techniques based on OCT phase information. During OCT imaging, a flicker stimulus could be applied to the retina synchronously by inserting a dichroic mirror in the imaging interface. An acute transient increase in total retinal blood flow could be detected. At the capillary level, an increase in the degree of speckle decorrelation in capillary OCT angiography images could also be observed, which indicates an increase in the velocity of blood at the capillary level. This method promises to be useful for the investigation of small animal models of ocular diseases.

Using frequency tagging to quantify attentional deployment in a visual divided attention task

NARCIS (Netherlands)

Toffanin, Paolo; de Jong, Ritske; Johnson, Addie; Martens, Sander

Frequency tagging is an EEG method based on the quantification of the steady state visual evoked potential (SSVEP) elicited from stimuli which flicker with a distinctive frequency. Because the amplitude of the SSVEP is modulated by attention such that attended stimuli elicit higher SSVEP amplitudes

2015 Inverter Workshop | Photovoltaic Research | NREL

Science.gov (United States)

Inverter Workshop 2015 Inverter Workshop Wednesday, February 25, 2015 Chair: Jack Flicker In about inverters. This workshop represented a follow-on to the inverter workshops that Sandia National conversations between module and inverter experts. Agenda For a detailed schedule of the day's events, access

The Need for Balance in Attack Aviation Employment Against Hybrid Threats

Science.gov (United States)

2014-06-13

they mitigate airpower as well as their ability to counter landpower. Cilluffo and Clark offer a further explanation of hybrid threats. Although...power radios, and the systematic manipulation of the power grids resulting in the flickering of the lights in certain towns to alert fighters...

Zinc Bromide Flow Battery Installation for Islanding and Backup Power

Science.gov (United States)

2016-09-18

specs delivered system common with other Gen1 deliveries • Cons: Requires 6mo extension • Risk Level: Mitigated through flexibility on deliverable...This in addition to interaction with the AE inverter started causing oscillations in the voltage control of the microgrid. Small flickers were

African Journal of AIDS Research - Vol 9, No 4 (2010)

African Journals Online (AJOL)

The effects of gender and socioeconomic status on youth sexual-risk norms: evidence from a poor urban community in South Africa · EMAIL FULL TEXT EMAIL FULL TEXT DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT. Michael Rogan, Michaela Hynie, Marisa Casale, Stephanie Nixon, Sarah Flicker, Geoff Jobson, ...

Nonlinear behavior in high-intensity discharge lamps

NARCIS (Netherlands)

Baumann, Bernd; Schwieger, Joerg; Wolff, Marcus; Manders, Freddy; Suijker, Jos

2016-01-01

The light flicker problem of high intensity discharge lamps is studied numerically and experimentally. It is shown that in some respects the systems behave very similar to the forced Duffing oscillator with a softening spring. In particular, the jump phenomenon and hysteresis are observed in the

Visual Temporal Processing in Dyslexia and the Magnocellular Deficit Theory: The Need for Speed?

Science.gov (United States)

McLean, Gregor M. T.; Stuart, Geoffrey W.; Coltheart, Veronika; Castles, Anne

2011-01-01

A controversial question in reading research is whether dyslexia is associated with impairments in the magnocellular system and, if so, how these low-level visual impairments might affect reading acquisition. This study used a novel chromatic flicker perception task to specifically explore "temporal" aspects of magnocellular functioning…

The impact of stimulus complexity and frequency swapping on stabilization of binocular rivalry

DEFF Research Database (Denmark)

Sandberg, Kristian; Bahrami, B; Lindeløv, Jonas Kristoffer

2011-01-01

high-level perceptual content. We conclude that overlaps at low visual stages are the most likely cause of the eye-specific stabilization for both stimulus types. Additionally, we examined the impact of swapping the flicker frequency of the images and found a general impact on stabilization...

Understanding Selective Downregulation of c-Myc Expression through Inhibition of General Transcription Regulators in Multiple Myeloma

Science.gov (United States)

2015-06-01

We next tested whether BET bromodomain inhibition mitigated the acti- vation of proadhesion pathways in aortic endothelium, which oc- curs during the...tinuum of activity as Myc flickers on and off of weakly bound, weakly expressed promoters, but stays longer or more frequently at high output promoters

Linking Returning Veterans in Rural Community Colleges to Mental Health Care

Science.gov (United States)

2015-09-01

limitation was mitigated somewhat by the use of non-response weights developed using the characteristics (age category, gender, race/ethnicity...American Journal of Psychiatry. 1998; 155:1092-1096. 7 Aud S, Wilkinson- Flicker S, Kristapovich P, Rathbun A, Wang X, Zhang J. The Condition of Education

Committee report on visual appearance of neon lights. Neon no hikari no miekata ni kansuru tokubetsu kenkyu iinkai hokoku

Energy Technology Data Exchange (ETDEWEB)

Kansaku, H. (Chukyo University, Nagoya (Japan). Faculty of Letters)

1991-04-25

Were summarized the results of experiments and literature searches, conducted by the Commettee on Visual Appearance of Neon Lights,'' which was set up to provide scientific and basic data for understanding of relationship between neon lights and psychological reaction of human, and for realizing of neon sign advertisements with playing a role as neon lights and without any environmental problems. Analytical results of influences of six colors, such as red, yellow, green, blue, violet, and white, brightnesses, and flickering frequencies to the psycological reaction of human on the direct observations of neon lights were described. Results of influences of the neon light incidence into the room to the psychology of residents were also introduced. Furthermore, evaluation of neon lights as an aspect was discussed. Consequently, based on the combination of activity and estimativity, some attentions to be payed on the setting-up of neon lights were pointed out. A red flickering neon light'' was given as clearly a bad example. 2 figs.

ICP-oa TOFMS utilisation to determine the Gd isotopic abundance in gadolinium nitrate

International Nuclear Information System (INIS)

Dragomir, M.; Ohai, D.; Dumitrescu, I.; Furtuna, I.

2010-01-01

This paper is describes the development of a method that should permit the determination of isotope abundance of gadolinium in gadolinium nitrate, used as burnable poison at Cernavoda NPP. To determine the isotopic abundance of gadolinium the inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometer (ICP-oa TOFMS) was used. The ICP-oa TOFMS allows the elimination of noise associated with instrumental drift and instability (flicker noise). The absence of flicker noise in the ICP-oa TOFMS means that the isotope ratios can be measured up to the statistical limit of ion counting. With TOFMS, each spectrum acquired represents signals from ions extracted from the plasma during the same time interval, formed from identical plasma and sample introduction events. Therefore, the ICP-oa TOFMS, Optimass 8000, has been successfully used for isotope ratio measurements of Gd in gadolinium nitrate [Gd (NO 3 ) 3 x 6H 2 O] sample solutions. (authors)

Grid impact of variable-speed wind turbines

Energy Technology Data Exchange (ETDEWEB)

Larsson, Aa [Chalmers Univ. of Technology, Dept. of Electric Power Engineering, Goeteborg (Sweden); Soerensen, P [Risoe National Lab., Roskilde (Denmark); Santjer, F [German Wind Energy Inst., DEWI, Wilhelmshaven (Germany)

1999-03-01

In this paper the power quality of variable-speed wind turbines equipped with forced-commutated inverters is investigated. Measurements have been taken on the same type of variable-speed wind turbines in Germany and Sweden. The measurements have been analysed according to existing IEC standards. Special attention has been paid to the aggregation of several wind turbines on flicker emission and harmonics. The aggregation has been compared with the summation laws used in the draft IEC 61400-21 `Power Quality Requirements for Grid Connected wind turbines`. The methods for calculating and summing flicker proposed by IEC Standards are reliable. Harmonics and inter-harmonics are treated in IEC 61000-4-7 and IEC 61000-3-6. The methods for summing harmonics and inter-harmonics in IEC 61000-3-6 are applicable to wind turbines. In order to obtain a correct magnitude of the frequency components, the use of a well-defined window width, according to IEC 61000-4-7 Amendment 1 is of a great importance. (au)

Effect of a single dose of dextromethorphan on psychomotor performance and working memory capacity.

Science.gov (United States)

Al-Kuraishy, Hayder M; Al-Gareeb, Ali I; Ashor, Ammar Waham

2012-04-01

Previous studies show that the prolonged use of dextromethorphan produces cognitive deterioration in humans. The aim of this study was to investigate the effect of a single dose of dextroemthrophan on psychomotor performance and working memory capacity. This is a randomized, double-blind, controlled, and prospective study. Thirty-six (17 women, 19 men) medical students enrolled in the study; half of them (7 women, 11 men) were given placebo, while the other half (10 women, 8 men) received dextromethorphan. The choice reaction time, critical flicker fusion threshold, and N-back working memory task were measured before and after 2 h of taking the drugs. Dextromethorphan showed a significant deterioration in the 3-back working memory task (P0.05). On the other hand, placebo showed no significant changes as regards the choice reaction time, critical flicker fusion threshold, and N-back working memory task (P>0.05). A single dose of dextromethorphan has no effect on attention and arousal but may significantly impair the working memory capacity.

New optical method for measuring the bending elasticity of lipid bilayers

International Nuclear Information System (INIS)

Minetti, C; Dubois, F; Vitkova, V; Bivas, I

2016-01-01

The knowledge of the elasticity of lipid bilayer structures is fundamental for new developments in biophysics, pharmacology and biomedical research. Lipid vesicles are readily prepared in laboratory conditions and employed for studying the physical properties of lipid membranes. The thermal fluctuation analysis of the shape of lipid vesicles (or flicker spectroscopy) is one of the experimental methods widely used for the measurement of the bending modulus of lipid bilayers. We present direct phase measurements performed on dilute vesicular suspensions by means of a new optical method exploiting holographic microscopy. For the bending constant of phosphatidylcholine bilayers we report the value of 23k B T in agreement with values previously measured by micropipette aspiration, electrodeformation and flicker spectroscopy of giant lipid vesicles. The application of this novel approach for the evaluation of the bending elasticity of lipid membranes opens the way to future developments in the phase measurements on lipid vesicles for the evaluation of their mechanical constants. (paper)

Soot volume fraction fields in unsteady axis-symmetric flames by continuous laser extinction technique.

Science.gov (United States)

Kashif, Muhammad; Bonnety, Jérôme; Guibert, Philippe; Morin, Céline; Legros, Guillaume

2012-12-17

A Laser Extinction Method has been set up to provide two-dimensional soot volume fraction field time history at a tunable frequency up to 70 Hz inside an axis-symmetric diffusion flame experiencing slow unsteady phenomena preserving the symmetry. The use of a continuous wave laser as the light source enables this repetition rate, which is an incremental advance in the laser extinction technique. The technique is shown to allow a fine description of the soot volume fraction field in a flickering flame exhibiting a 12.6 Hz flickering phenomenon. Within this range of repetition rate, the technique and its subsequent post-processing require neither any method for time-domain reconstruction nor any correction for energy intrusion. Possibly complemented by such a reconstruction method, the technique should support further soot volume fraction database in oscillating flames that exhibit characteristic times relevant to the current efforts in the validation of soot processes modeling.

Cone dysfunctions in retinitis pigmentosa with retinal nerve fiber layer thickening.

Science.gov (United States)

Sobacı, Güngör; Ozge, Gökhan; Gündoğan, Fatih Ç

2012-01-01

To investigate whether or not thicker retinal nerve fiber layer (RNFL) in retinitis pigmentosa (RP) patients relates to functional abnormalities of the photoreceptors. Optical coherence tomography-based RNFL thickness was measured by Stratus-3™ (Zeiss, Basel, Switzerland) optical coherence tomography and electroretinogram (ERG) recordings made using the RETI-port(®) system (Roland, Wiesbaden, Germany) in 27 patients with retinitis pigmentosa and in 30 healthy subjects. Photopic ERG b-wave amplitude, cone ERG b-wave latency, 30 Hz flicker amplitude, and 30 Hz flicker latency had significant correlations to the RNFL-temporal (r = -0.55, P = 0.004, r = 0.68, P = 0.001, r = -0.65, P = 0.001, and r = -0.52, P = 0.007, respectively). Eyes with thicker RNFL (ten eyes) differed significantly from those with thinner RNFL (eight eyes) regarding cone ERG b-wave latency values only (P = 0.001). Thicker RNFL in patients with retinitis pigmentosa may be associated with functional abnormality of the cone system.

Visual function and long-term chloroquine treatment

African Journals Online (AJOL)

Amsler grids and a further battery offour tests of macular function (visual evoked potentials, criti- cal flicker fusion threshold, Cambridge contrast sensitivity and the macular dazzle test) were administered. No case of retinal pigmentary abnonnalities plus visual loss was found, but 2 patients were advised to cease chloroquine.

Performance of barcode scanner using peak detection with interference from LED lamps

NARCIS (Netherlands)

Deng, X.; Zijlstra, P.; Zhang, J.; Wu, Y.; Zhou, G.; Linnartz, J.-P.

2015-01-01

This paper presents a new model for barcode scanners that suffer from the interference of LED lamps, to quantify the system performance in terms of Timing Signal-to-Interference Ratio (TSIR), particularly as a function of modulation depth and frequency of the flicker in the LED lighting. Physical

Improving Visual Threat Detection: Research to Validate the Threat Detection Skills Trainer

Science.gov (United States)

2013-08-01

26 Threat Detection and Mitigation Strategies...quicker when identifying threats in relevant locations. This task utilized the Flicker paradigm (Rensink, O’Regan, & Clark, 1997; Scholl, 2000...the meaning and implication of threats, why cues were relevant, strategies used to detect and mitigate threats, and challenges when attempting to

Magnetometry with Ensembles of Nitrogen Vacancy Centers in Bulk Diamond

Science.gov (United States)

2015-10-23

the ESR curve. Any frequency components of the photodetector signal which are not close to the reference frequency, are filtered out. This mitigates ...indicating that we have not yet run up against thermal or flicker noise for these time scales. 5.3 Details of frequency modulation circuit In order

SAVEWS Jr. User’s Manual, Version 1.0

Science.gov (United States)

2014-04-01

recording sessions are more susceptible to data loss, such as from a power flicker . Second, it will probably be necessary to process a file...not covered in this document. One means of mitigating false SAV detections due to debris is to set the maxplantdepth variable in the configuration

Enhanced Thermionic Emission and Low 1/f Noise in Exfoliated Graphene/GaN Schottky Barrier Diode.

Science.gov (United States)

Kumar, Ashutosh; Kashid, Ranjit; Ghosh, Arindam; Kumar, Vikram; Singh, Rajendra

2016-03-01

Temperature-dependent electrical transport characteristics of exfoliated graphene/GaN Schottky diodes are investigated and compared with conventional Ni/GaN Schottky diodes. The ideality factor of graphene/GaN and Ni/GaN diodes are measured to be 1.33 and 1.51, respectively, which is suggestive of comparatively higher thermionic emission current in graphene/GaN diode. The barrier height values for graphene/GaN diode obtained using thermionic emission model and Richardson plots are found to be 0.60 and 0.72 eV, respectively, which are higher than predicted barrier height ∼0.40 eV as per the Schottky-Mott model. The higher barrier height is attributed to hole doping of graphene due to graphene-Au interaction which shifts the Fermi level in graphene by ∼0.3 eV. The magnitude of flicker noise of graphene/GaN Schottky diode increases up to 175 K followed by its decrease at higher temperatures. This indicates that diffusion currents and barrier inhomogeneities dominate the electronic transport at lower and higher temperatures, respectively. The exfoliated graphene/GaN diode is found to have lower level of barrier inhomogeneities than conventional Ni/GaN diode, as well as earlier reported graphene/GaN diode fabricated using chemical vapor deposited graphene. The lesser barrier inhomogeneities in graphene/GaN diode results in lower flicker noise by 2 orders of magnitude as compared to Ni/GaN diode. Enhanced thermionic emission current, lower level of inhomogeneities, and reduced flicker noise suggests that graphene-GaN Schottky diodes may have the underlying trend for replacing metal-GaN Schottky diodes.

Ontogenetic improvement of visual function in the medaka Oryzias latipes based on an optomotor testing system for larval and adult fish

Science.gov (United States)

Carvalho, Paulo S. M.; Noltie, Douglas B.; Tillitt, D.E.

2002-01-01

We developed a system for evaluation of visual function in larval and adult fish. Both optomotor (swimming) and optokinetic (eye movement) responses were monitored and recorded using a system of rotating stripes. The system allowed manipulation of factors such as width of the stripes used, rotation speed of the striped drum, and light illuminance levels within both the scotopic and photopic ranges. Precise control of these factors allowed quantitative measurements of visual acuity and motion detection. Using this apparatus, we tested the hypothesis that significant posthatch ontogenetic improvements in visual function occur in the medaka Oryzias latipes, and also that this species shows significant in ovo neuronal development. Significant improvements in the acuity angle alpha (ability to discriminate detail) were observed from approximately 5 degrees at hatch to 1 degree in the oldest adult stages. In addition, we measured a significant improvement in flicker fusion thresholds (motion detection skills) between larval and adult life stages within both the scotopic and photopic ranges of light illuminance. Ranges of flicker fusion thresholds (X±SD) at log I=1.96 (photopic) varied from 37.2±1.6 cycles/s in young adults to 18.6±1.6 cycles/s in young larvae 10 days posthatch. At log I=−2.54 (scotopic), flicker fusion thresholds varied from 5.8±0.7 cycles/s in young adults to 1.7±0.4 cycles/s in young larvae 10 days posthatch. Light sensitivity increased approximately 2.9 log units from early hatched larval stages to adults. The demonstrated ontogenetic improvements in visual function probably enable the fish to explore new resources, thereby enlarging their fundamental niche.

Optical spectrophotometry of oscillations and flickering in AE Aquarii

Science.gov (United States)

Welsh, William F.; Horne, Keith; Oke, J. B.

1993-01-01

We observed rapid variations in the nova-like cataclysmic variable AE Aquarii for 1.7 hr with 4.3 s time resolution using the 30-channel (3227-10494 A) spectrophotometer on the Hale 5 m telescope. The 16.5 and 33.0 s oscillations show a featureless blue spectrum that can be represented by a blackbody with temperature and area much smaller than the accretion disk. Models consisting of the sum of a K star spectrum and a hydrogen slab in LTE at T = 6000-10,000 K can fit the spectrum of AE Aquarii reasonably well. The spectrum of a flare indicates optically thin gas with T = 8000-12,000 K. The energy released by the flare is large compared to typical stellar flares.

Flicker (1/f) noise in tunnel junction DC SQUIDS

International Nuclear Information System (INIS)

Koch, R.H.; Clarke, J.; Goubau, W.M.; Martinis, J.M.; Pegrum, C.M.; Van Harlingen, D.J.

1983-01-01

We have measured the spectral density of the 1/f voltage noise in current-biased resistively shunted Josephson tunnel junctions and dc SQUIDs. A theory in which fluctuations in the temperature give rise to fluctuations in the critical current and hence in the voltage predicts the magnitude of the noise quite accurately for junctions with areas of about 2 x 10 4 μm 2 , but significantly overestimates the noise for junctions with areas of about 6 μm 2 . DC SQUIDs fabricated from these two types of junctions exhibit substantially more 1/f voltage noise than would be predicted from a model in which the noise arises from critical current fluctuations in the junctions. This result was confirmed by an experiment involving two different bias current and flux modulation schemes, which demonstrated that the predominant 1/f voltage noise arises not from critical current fluctuations, but from some unknown source that can be regarded as an apparent 1/f flux noise. Measurements on five different configurations of dc SQUIDs fabricated with thin-film tunnel junctions and with widely varying areas, inductances, and junction capacitances show that the spectral density of the 1/f equivalent flux noise is roughtly constant, within a factor of three of (10 -10 /f)phi 2 0 Hz -1 . It is emphasized that 1/f flux noise may not be the predominant source of 1/f noise in SQUIDS fabricated with other technologies

GATEWAY Report Brief: Evaluating OLED Lighting in the Accounting Office of DeJoy, Knauf & Blood LLP

Energy Technology Data Exchange (ETDEWEB)

None

2017-08-21

Summary of GATEWAY report evaluating a new lighting system, at the offices of the accounting firm of DeJoy, Knauf & Blood, LLP in Rochester, NY, that incorporates a number of different OLED luminaires. Evaluation of the OLED products included efficacy performance, field measurements of panel color, flicker measurements, and staff feedback.

Nonlinear behavior in high-intensity discharge lamps

Science.gov (United States)

Baumann, Bernd; Schwieger, Joerg; Wolff, Marcus; Manders, Freddy; Suijker, Jos

2016-06-01

The light flicker problem of high intensity discharge lamps is studied numerically and experimentally. It is shown that in some respects the systems behave very similar to the forced Duffing oscillator with a softening spring. In particular, the jump phenomenon and hysteresis are observed in the simulations and in the experiments.

Food habits of Northern Goshawks nesting in south central Wyoming

Science.gov (United States)

John R. Squires

2000-01-01

Northern Goshawks (Accipiter gentiles) nesting in south central Wyoming consumed at least 33 species of prey; 14 were mammals and 19 were birds. Based on percent occurrence in regurgitated pellets, dominant (>10% frequency) prey species included: red squirrel (Tamiasciurus hudsonicus; present in 50% of pellets), Northern Flicker (Colaptes auratus; 34...

Guidance of Attention to Objects and Locations by Long-Term Memory of Natural Scenes

Science.gov (United States)

Becker, Mark W.; Rasmussen, Ian P.

2008-01-01

Four flicker change-detection experiments demonstrate that scene-specific long-term memory guides attention to both behaviorally relevant locations and objects within a familiar scene. Participants performed an initial block of change-detection trials, detecting the addition of an object to a natural scene. After a 30-min delay, participants…

GATEWAY Demonstrations: OLED Lighting in the Offices of DeJoy, Knauf & Blood, LLP

Energy Technology Data Exchange (ETDEWEB)

Miller, Naomi J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2017-07-24

At the offices of the accounting firm of DeJoy, Knauf & Blood, LLP in Rochester, NY, the GATEWAY program evaluated a new lighting system that incorporates a number of different OLED luminaires. Evaluation of the OLED products included efficacy performance, field measurements of panel color, flicker measurements, and staff feedback.

BREAKING STOVEPIPES: BRIDGING GAPS IN AIR FORCE INDUSTRIAL CONTROL SYSTEMS MANAGEMENT TO ENABLE MULTI-DOMAIN MISSION ASSURANCE

Science.gov (United States)

2016-02-16

sputter, and lights flicker and fail. An in-bound F-35, returning from its first strike mission for a quick-turn, has to divert as the runway is not ready...and mitigating risk of known vulnerabilities.” United States Scientific Advisory Board, Report on Defending and Operating in a Contested Cyber

Introduction and Validation of Chromium-Free Consumables for Welding Stainless Steels. Version 2

Science.gov (United States)

2015-04-14

for Cr(VI) mitigation . There are potential uses for this process at DoD original equipment manufacturers such as power plants for submarines and...is smooth and spray-like in fine droplets. The arc may flicker in intensity, but no extinctions occur. 6-4 Some manipulation may be required to

How Adolescents with Autism Spectrum Disorder (ASD) Spontaneously Attend to Real-World Scenes: Use of a Change Blindness Paradigm

Science.gov (United States)

Hochhauser, Michal; Aran, Adi; Grynszpan, Ouriel

2018-01-01

Visual attention of adolescents with autism spectrum disorder (ASD) was assessed using a change blindness paradigm. Twenty-five adolescents with ASD aged 12-18 years and 25 matched typically developing (TD) adolescents viewed 36 pairs of digitized real-world images. Each pair of images was displayed in a "flicker paradigm" whereby a…

Theory of 1/f noise-a new approach

International Nuclear Information System (INIS)

Kroupa, V.F.

2005-01-01

In the present contribution we will discuss a new mathematical model for generation of the 1/f or flicker noise by introducing the sampling process and emphasizing the necessity for flow of a medium-current, energy, etc. The new theory will be confronted with 1/f noise generated in crystal resonators and oscillators

Development and Characterization of a High Speed Mid-IR Tunable Diode Laser Absorption Spectrometer for CO and CO2 Detection in Detonation Events

Science.gov (United States)

2014-03-27

intense beam hitting the final element. Over- filling the detector also helped to mitigate any effects that occurred due to beam steering within the flame...out flame effects such as flame flicker as well as any ambient room fluctuations. A representative sample of the data is shown in Figure 4.1. The first

The Noncommissioned Officer and Petty Officer: Backbone of the Armed Forces

Science.gov (United States)

2014-01-01

cherish, and others may envy. The patriotic flame that burns within every Servicemember is sometimes threatened and can occasionally flicker from the...their crews. “You Have to Go Out but You Don’t Have to Come Back.” Coast- guardsmen are taught to avoid or mitigate unnecessary risk, but this historic

Habitat-mediated variation in the importance of ecosystem engineers for secondary cavity nesters in a nest web.

Science.gov (United States)

Robles, Hugo; Martin, Kathy

2014-01-01

Through physical state changes in biotic or abiotic materials, ecosystem engineers modulate resource availability to other organisms and are major drivers of evolutionary and ecological dynamics. Understanding whether and how ecosystem engineers are interchangeable for resource users in different habitats is a largely neglected topic in ecosystem engineering research that can improve our understanding of the structure of communities. We addressed this issue in a cavity-nest web (1999-2011). In aspen groves, the presence of mountain bluebird (Sialia currucoides) and tree swallow (Tachycineta bicolour) nests was positively related to the density of cavities supplied by northern flickers (Colaptes auratus), which provided the most abundant cavities (1.61 cavities/ha). Flickers in aspen groves provided numerous nesting cavities to bluebirds (66%) and swallows (46%), despite previous research showing that flicker cavities are avoided by swallows. In continuous mixed forests, however, the presence of nesting swallows was mainly related to cavity density of red-naped sapsuckers (Sphyrapicus nuchalis), which provided the most abundant cavities (0.52 cavities/ha), and to cavity density of hairy woodpeckers (Picoides villosus), which provided few (0.14 cavities/ha) but high-quality cavities. Overall, sapsuckers and hairy woodpeckers provided 86% of nesting cavities to swallows in continuous forests. In contrast, the presence of nesting bluebirds in continuous forests was associated with the density of cavities supplied by all the ecosystem engineers. These results suggest that (i) habitat type may mediate the associations between ecosystem engineers and resource users, and (ii) different ecosystem engineers may be interchangeable for resource users depending on the quantity and quality of resources that each engineer supplies in each habitat type. We, therefore, urge the incorporation of the variation in the quantity and quality of resources provided by ecosystem engineers

Wind turbines and human health

Directory of Open Access Journals (Sweden)

Loren eKnopper

2014-06-01

Full Text Available The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation (electromagnetic fields (EMF, shadow flicker, audible noise, low frequency noise, infrasound. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low frequency noise and infrasound, EMF and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low frequency noise and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance especially at sound pressure levels >40 dB(A. Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health.

Wind turbines and human health.

Science.gov (United States)

Knopper, Loren D; Ollson, Christopher A; McCallum, Lindsay C; Whitfield Aslund, Melissa L; Berger, Robert G; Souweine, Kathleen; McDaniel, Mary

2014-01-01

The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40 dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health.

ERG and other discriminators between advanced hydroxychloroquine retinopathy and retinitis pigmentosa.

Science.gov (United States)

Nair, Archana A; Marmor, Michael F

2017-06-01

To study whether the ERG and other clinical findings help to distinguish between advanced hydroxychloroquine (HCQ) retinopathy and pericentral or diffuse retinitis pigmentosa (RP) with similar fundus appearance. We conducted a retrospective analysis of patients with advanced HCQ retinopathy (n = 11), pericentral RP (n = 8) and diffuse RP (n = 8). Pericentral RP was defined as having limited fundus damage and relatively normal flicker ERG time-to-peak. Diffuse RP had typical loss of the rod ERG and flicker timing delay. All patients showed reduced amplitude of the ISCEV responses in the full-field electroretinogram (ERG). Aspects of history, visual field results, fundus appearance, fundus autofluorescence and ocular coherence tomography were also compared. Relative to pericentral RP, patients with HCQ toxicity showed delayed flicker ERG time-to-peak and lower ERG amplitudes, particularly combined rod-cone responses. Relative to diffuse RP, most HCQ toxicity patients had some preserved rod ERG response, and there was no obvious predilection for rod over cone damage. In addition, patients with HCQ toxicity usually lacked markers of long-standing degeneration such as bone spicule figures or severe loss of peripheral field. History of familial disease and long-standing night blindness were specific to RP. While the early signs of HCQ damage are typically regional in the posterior pole, advanced disease is characteristically diffuse (unlike pericentral RP). This is appropriate for a systemic toxin, as is the finding that rods and cones were both affected in the ERG to a similar degree (unlike genetic rod-cone dystrophies). For patients with severe HCQ exposure and some of our discriminatory findings, and no family history or prior night blindness, HCQ toxicity is a sufficient diagnosis without invoking a second rare disease (Occam's razor).

Wind Turbines and Human Health

Science.gov (United States)

Knopper, Loren D.; Ollson, Christopher A.; McCallum, Lindsay C.; Whitfield Aslund, Melissa L.; Berger, Robert G.; Souweine, Kathleen; McDaniel, Mary

2014-01-01

The association between wind turbines and health effects is highly debated. Some argue that reported health effects are related to wind turbine operation [electromagnetic fields (EMF), shadow flicker, audible noise, low-frequency noise, infrasound]. Others suggest that when turbines are sited correctly, effects are more likely attributable to a number of subjective variables that result in an annoyed/stressed state. In this review, we provide a bibliographic-like summary and analysis of the science around this issue specifically in terms of noise (including audible, low-frequency noise, and infrasound), EMF, and shadow flicker. Now there are roughly 60 scientific peer-reviewed articles on this issue. The available scientific evidence suggests that EMF, shadow flicker, low-frequency noise, and infrasound from wind turbines are not likely to affect human health; some studies have found that audible noise from wind turbines can be annoying to some. Annoyance may be associated with some self-reported health effects (e.g., sleep disturbance) especially at sound pressure levels >40 dB(A). Because environmental noise above certain levels is a recognized factor in a number of health issues, siting restrictions have been implemented in many jurisdictions to limit noise exposure. These setbacks should help alleviate annoyance from noise. Subjective variables (attitudes and expectations) are also linked to annoyance and have the potential to facilitate other health complaints via the nocebo effect. Therefore, it is possible that a segment of the population may remain annoyed (or report other health impacts) even when noise limits are enforced. Based on the findings and scientific merit of the available studies, the weight of evidence suggests that when sited properly, wind turbines are not related to adverse health. Stemming from this review, we provide a number of recommended best practices for wind turbine development in the context of human health. PMID:24995266

Brain-computer interface based on intermodulation frequency

Science.gov (United States)

Chen, Xiaogang; Chen, Zhikai; Gao, Shangkai; Gao, Xiaorong

2013-12-01

Objective. Most recent steady-state visual evoked potential (SSVEP)-based brain-computer interface (BCI) systems have used a single frequency for each target, so that a large number of targets require a large number of stimulus frequencies and therefore a wider frequency band. However, human beings show good SSVEP responses only in a limited range of frequencies. Furthermore, this issue is especially problematic if the SSVEP-based BCI takes a PC monitor as a stimulator, which is only capable of generating a limited range of frequencies. To mitigate this issue, this study presents an innovative coding method for SSVEP-based BCI by means of intermodulation frequencies. Approach. Simultaneous modulations of stimulus luminance and color at different frequencies were utilized to induce intermodulation frequencies. Luminance flickered at relatively large frequency (10, 12, 15 Hz), while color alternated at low frequency (0.5, 1 Hz). An attractive feature of the proposed method was that it would substantially increase the number of targets at a single flickering frequency by altering color modulated frequencies. Based on this method, the BCI system presented in this study realized eight targets merely using three flickering frequencies. Main results. The online results obtained from 15 subjects (14 healthy and 1 with stroke) revealed that an average classification accuracy of 93.83% and information transfer rate (ITR) of 33.80 bit min-1 were achieved using our proposed SSVEP-based BCI system. Specifically, 5 out of the 15 subjects exhibited an ITR of 40.00 bit min-1 with a classification accuracy of 100%. Significance. These results suggested that intermodulation frequencies could be adopted as steady responses in BCI, for which our system could be used as a practical BCI system.

A Brain-Machine-Brain Interface for Rewiring of Cortical Circuitry after Traumatic Brain Injury

Science.gov (United States)

2015-11-01

simplicity, with 15b representation at its internal nodes to mitigate quantization noise effects on template signal accuracy [18]. The digitized/filtered...HCF was adjustable in the range of 6.4–12.3 kHz. In the right plot, note how the Gm-C HPF effectively removed the flicker noise contribution, when the

Flame synthesis of carbon nano-onions enhanced by acoustic modulation

Energy Technology Data Exchange (ETDEWEB)

Chung, De-Hua; Lin, Ta-Hui [Department of Mechanical Engineering, National Cheng Kung University, Tainan 70101, Taiwan (China); Hou, Shuhn-Shyurng, E-mail: sshou@mail.ksu.edu.tw [Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 70101, Taiwan (China)

2010-10-29

Ethylene jet diffusion flames modulated by acoustic excitation in an atmospheric environment were used to synthesize carbon nano-onions (CNOs) on a catalytic nickel substrate. The formation of CNOs was significantly enhanced by acoustic excitation at frequencies near either the natural flickering frequency or the acoustically resonant frequency. The rate of yield of CNOs was high at 10 and 20 Hz (near the natural flickering frequency) for a sampling position z = 5 mm above the burner exit where the gas temperature was about 450-520 deg. C, or at 10, 20 and 30 Hz for z = 10 mm with the gas temperature ranging from 420 to 500 deg. C. Additionally, for both z = 5 and 10 mm, a quantity of CNOs can be obtained at 60-70 Hz, near the acoustically resonant frequency, where the gas temperature was between 620 and 720 deg. C. Almost no CNOs were produced for the other frequencies due to low temperature or lack of carbon sources. CNOs synthesized at low frequencies had a greater diameter and a higher degree of graphitization than those at high frequencies.

Stereoscopy and the Human Visual System

Science.gov (United States)

Banks, Martin S.; Read, Jenny C. A.; Allison, Robert S.; Watt, Simon J.

2012-01-01

Stereoscopic displays have become important for many applications, including operation of remote devices, medical imaging, surgery, scientific visualization, and computer-assisted design. But the most significant and exciting development is the incorporation of stereo technology into entertainment: specifically, cinema, television, and video games. In these applications for stereo, three-dimensional (3D) imagery should create a faithful impression of the 3D structure of the scene being portrayed. In addition, the viewer should be comfortable and not leave the experience with eye fatigue or a headache. Finally, the presentation of the stereo images should not create temporal artifacts like flicker or motion judder. This paper reviews current research on stereo human vision and how it informs us about how best to create and present stereo 3D imagery. The paper is divided into four parts: (1) getting the geometry right, (2) depth cue interactions in stereo 3D media, (3) focusing and fixating on stereo images, and (4) how temporal presentation protocols affect flicker, motion artifacts, and depth distortion. PMID:23144596

Power system frequency estimation based on an orthogonal decomposition method

Science.gov (United States)

Lee, Chih-Hung; Tsai, Men-Shen

2018-06-01

In recent years, several frequency estimation techniques have been proposed by which to estimate the frequency variations in power systems. In order to properly identify power quality issues under asynchronously-sampled signals that are contaminated with noise, flicker, and harmonic and inter-harmonic components, a good frequency estimator that is able to estimate the frequency as well as the rate of frequency changes precisely is needed. However, accurately estimating the fundamental frequency becomes a very difficult task without a priori information about the sampling frequency. In this paper, a better frequency evaluation scheme for power systems is proposed. This method employs a reconstruction technique in combination with orthogonal filters, which may maintain the required frequency characteristics of the orthogonal filters and improve the overall efficiency of power system monitoring through two-stage sliding discrete Fourier transforms. The results showed that this method can accurately estimate the power system frequency under different conditions, including asynchronously sampled signals contaminated by noise, flicker, and harmonic and inter-harmonic components. The proposed approach also provides high computational efficiency.

How is plasma profile determined?

International Nuclear Information System (INIS)

Itoh, Kimitaka; Itoh, Sanae

1991-01-01

The plasma of toroidal system magnetic field confinement which is represented by tokamak is realized as dissipating structure which is maintained by the supply of energy and particles. Besides the spatial distributions of heat, particles and momentum inside plasma take various forms, there are the transition phenomena among the distributions with different forms, intermittent energy loss, the exchange of spatial positions among ions and so on, accordingly confined plasma is the treasure house of the transport phenomena accompanied by various temporal and spatial scales. Now might be the time that the unknown physics being concealed with veil becomes clear. In this report, by taking tokamaks as the example, concerning the transport phenomena in plasma, the recent development on the physical phenomena and the comparison of the theoretical model with the experiment is explained. The formulation of transport phenomena, the elementary process of transport by flickering, transport matrix, waves in drift frequency band, boundary condition, the comparison of transport in steady state, the research on the time change of distribution, and the correlation of flickering and transport are described. (K.I.)

Frequency Domain Electroretinography in Retinitis Pigmentosa versus Normal Eyes

Directory of Open Access Journals (Sweden)

Homa Hassan-Karimi

2012-01-01

Full Text Available Purpose: To compare electroretinogram (ERG characteristics in patients with retinitis pigmentosa (RP and normal subjects using frequency domain analysis. Methods: Five basic ERG recordings were performed in normal subjects and patients with a clinical diagnosis of RP according to the ISCEV (International Society of Clinical Electrophysiology of Vision protocol. Frequency domain analysis was performed by MATLAB software. Different frequency domain parameters were compared between the study groups. Results: Peak frequency (Fmod of flicker and oscillatory responses in RP patients showed significant (P<0.0001 high pass response as compared to normal controls. Peak frequency (Fmod of the other responses was not significantly different between the two groups. Conclusion: In addition to conventional ERG using time domain methods, frequency domain analysis may be useful for diagnosis of RP. Oscillatory and flicker responses may be analyzed in frequency domain. Fast Fourier transform may reveal two distinct high pass responses (shift to higher frequencies in Fmod. Time and frequency domain analyses may be performed simultaneously with many modern ERG machines and may therefore be recommended in RP patients.

Flicking technique for microencapsulation of cells in calcium alginate leading to the microtissue formation.

Science.gov (United States)

Wong, Soon Chuan; Soon, Chin Fhong; Leong, Wai Yean; Tee, Kian Sek

2016-01-01

Microbeads have wide applications in biomedical engineering field that include drug delivery, encapsulation of biomolecules, tissue padding and tissue regeneration. In this paper, we report a simple, yet efficient, flicking technique to produce microcapsules of calcium alginate at a narrow distribution of size. The system consists of an infusion pump and a customised flicker that taps the syringe needle for dispersing microcapsules of sodium alginate that polymerised in the calcium chloride solution. The flow rate of the syringe pump and the velocity of the flicker were studied to achieve a well controlled and tunable size distribution of microbeads ranging from 200 to 400 μm. At a flow rate of 4 μl/min and flicking rate of 80 rpm, a narrow size distribution of microbeads were produced. Via this technique, HaCaT cells were encapsulated in calcium alginate microbeads that grown into microtissues with a size ranging from 100 to 300 μm after two weeks of culture. These microtissues could be potentially useful for pharmacological application.

Perceptual-cognitive expertise of handball coaches in their young and middle adult years.

Science.gov (United States)

Fischer, Lennart; Baker, Joseph; Rienhoff, Rebecca; Strauß, Bernd; Tirp, Judith; Büsch, Dirk; Schorer, Jörg

2016-09-01

There is little research investigating the maintenance of perceptual-cognitive expertise in general and even less comparing coaches of different ages. The aim of this study was to test for perceptual-cognitive differences between age groups, licence levels, and their interaction. This study investigated differences in skilled performance between young and middle-aged coaches of three different skill levels. Participants performed an accuracy-oriented pattern recall (mean distance in pixel) and a time-oriented flicker test (mean detection time in ms). There were some significant differences between age groups and between skill groups for both tests, but no interactions. For the pattern recall test, the effect sizes were larger for skill level differences, while for the flicker test effects were larger for ageing. These results suggest coaches are able to maintain accuracy skills better than reaction timed tasks. This is in line with findings on speeded performance in general populations, which show declines with age. Moreover, results also support findings on perceptual expertise in skills where accuracy was important.

Environmental Assessment for the Construction and Operation of an Indoor Small Arms Range at Niagara Falls Air Reserve Station, New York

Science.gov (United States)

2009-08-01

Name Northern flicker Colaptes auratus Northern harrier2 Circus cyaneus Northern mockingbird Mimus polyglottos Northern rough-winged swallow...Installation operations impact wildlife habitat. Disturbance of vegetation by construction. Displacement and potential to kill or injure...Unless otherwise permitted by regulations, the MBTA makes it unlawful to pursue, hunt, take, capture, or kill ; attempt to take, capture or kill

The JPL Hg(sup +) Extended Linear Ion Trap Frequency Standard: Status, Stability, and Accuracy Prospects

Science.gov (United States)

Tjoelker, R. L.; Prestage, J. D.; Maleki, L.

1996-01-01

Microwave frequency standards based on room temperature (sup 199)Hg(sup +) ions in a Linear Ion Trap (LITS) presently achieve a Signal to Noise and line Q inferred short frequency stability. Long term stability has been measured for averaging intervals up to 5 months with apparent sensitivity to variations in ion number/temperature limiting the flicker floor.

Demonstration and Validation of a Waste-to-Energy Conversion System for Fixed DoD Installations

Science.gov (United States)

2013-09-01

equipment replacement costs. Mixed Result. Single point failures were observed, but were determined to be feedstock specific. Mitigation strategies have...40 kWe net electric output. Power quality Variations in voltage, frequency, flicker , harmonics, power factor and direct current injection...replacement costs. Mixed Result. Single point failures were observed, but were determined to be feedstock specific. Mitigation strategies have

Finding of No Significant Impact & Tiered Environmental Assessment: Public Law 84-99 Rehabilitation Program Levee Unit 624-627 - Mosquito Creek Pottawattamie County, Iowa

Science.gov (United States)

2014-10-01

spp.), northern flicker (Colaptes auratus), red-headed woodpecker (Melanerpes erythrocephalus), wild turkey (Meleagris gallopavo), eastern kingbird...aquatic environment. Some commenters asked that compensatory mitigation be required for all activities authorized by this NWP. A few commenters...remarked that compensatory mitigation should be required for adverse effects on high quality riparian areas. Another commenter said that mitigation should

Theta-paced flickering between place-cell maps in the hippocampus

Czech Academy of Sciences Publication Activity Database

Ježek, Karel; Henriksen, E. J.; Treves, A.; Moser, E. I.; Moser, M.B.

2011-01-01

Roč. 478, č. 7368 (2011), s. 246-249 ISSN 0028-0836 R&D Projects: GA MŠk(CZ) LC554; GA MŠk(CZ) 1M0517 Institutional research plan: CEZ:AV0Z50110509 Keywords : memory * theta * hippocampus * place cells * teleportation Subject RIV: FH - Neurology Impact factor: 36.280, year: 2011

Simulation of interaction between wind farm and power system[Flicker

Energy Technology Data Exchange (ETDEWEB)

Soerensen, P.; Hansen, A.; Janosi, L.; Bech, J.; Bak-Jensen, B.

2001-12-01

A dynamic model of the wind farm Hagesholm has been implemented in the dedicated power system simulation program DIgSILENT. The wind farm consists of six 2MW NM2000/72 wind turbines from NEG-Micon. The model has been verified using simultaneous power quality measurements on the 10 kV terminals of a single wind turbine and power performance measurements on two wind turbines. The verification shows a generally good agreement between simulations and measurements, although the simulations at higher wind speeds seem to underestimate the power and voltage fluctuations. A way to improve the simulation at higher wind speeds is suggested. (au)

Reconnaissance Waccamaw River Basin North Carolina and South Carolina. Flood Control and Related Purposes.

Science.gov (United States)

1981-09-01

carota), horseweed (Erigeron canadensis), plantain (Plantago lanceolata, P. virginica, P. aristata), horse nettle (Solanum carolinense), dog fennel... insects that are used for food by the red-eyed vireo, scarlet tanager, tufted titmouse, common flicker, and various warblers. The abundant birds and...Detritivores, including immature stages of aquatic insects , small arthropods, and annelid worms, which thrive in this wetland community are consumed

H1 antihistamines and driving

OpenAIRE

Florin-Dan, Popescu

2008-01-01

Driving performances depend on cognitive, psychomotor and perception functions. The CNS adverse effects of some H1 antihistamines can alter the patient ability to drive. Data from studies using standardized objective cognitive and psychomotor tests (Choice Reaction Time, Critical Flicker Fusion, Digital Symbol Substitution Test), functional brain imaging (Positron Emission Tomography, functional Magnetic Resonance Imaging), neurophysiological studies (Multiple Sleep Latency Test, auditory and...

America’s Achilles Heel: Defense Against High-altitude Electromagnetic Pulse-policy vs. Practice

Science.gov (United States)

2014-12-12

between milestones. Recommendations will address both governmental and private sector approaches to EMP damage mitigation and consequence management. 15...governmental and private sector approaches to EMP damage mitigation and consequence management. iv ACKNOWLEDGMENTS This is study is dedicated to the men...check engine light flicker 1 James Wesley Rawles, Patriots: Surviving the Coming Collapse, 4th ed. (Berkeley, CA: Ulysses Press), 1. 1

Estudo normativo do eletrorretinograma de campo total em adultos jovens Normative values for full-field electroretinogram in healthy young adults

Directory of Open Access Journals (Sweden)

Josenilson Martins Pereira

2003-01-01

Full Text Available OBJETIVOS: A proposta deste estudo é estabelecer valores normativos para o eletrorretinograma (ERG de campo total, em um grupo de voluntários adultos jovens segundo o protocolo padrão recomendado pela Sociedade Internacional de Eletrofisiologia Visual Clínica (ISCEV. MÉTODOS: Participaram deste estudo 42 voluntários normais com idades variando de 15 a 26 anos, sendo 20 homens e 22 mulheres. Os eletrorretinogramas de campo total foram obtidos com eletrodos de lente de contato bipolares e seguiram as 5 etapas do protocolo da Sociedade Internacional de Eletrofisiologia Visual Clinica: a resposta de bastonetes; b reposta máxima; c potenciais oscilatórios; d resposta máxima de cones; e resposta de cones ao flicker 30 Hz. Os parâmetros analisados foram a amplitude de resposta do pico da onda-a até o pico da onda-b (pico a pico em miV e o tempo de culminação da onda-b (ms. RESULTADOS: As médias (± 1 desvio padrão da amplitude pico a pico foram: resposta de bastonetes - 241,1 ± 66,9 µV; resposta máxima - 385,4 ± 71,8 µV; potenciais oscilatórios - 180,6 ± 48,6 µV; resposta de cones -102,8 ± 36,3 µV e flicker 30 Hz - 69,2 ± 26,6 µV. Para o tempo implícito da onda-b os valores foram: resposta de bastonetes - 85,2 ± 7,6 ms; resposta máxima -45,6 ± 2,0ms; resposta de cones - 27,8 ± 1,2ms e flicker 30 Hz - 27,9 ± 1,2 ms. Os resultados foram comparáveis entre os grupos masculino e feminino, exceto para a resposta máxima em que as mulheres obtiveram amplitudes estatisticamente maiores (t=2,06; P=0,046. CONCLUSÃO: Os valores encontrados estão de acordo com dados normativos da literatura e são fundamentais para o diagnóstico correto de disfunções retinianas em pacientes na mesma faixa etária. Inclusão de outras faixas etárias e o aumento no número de sujeitos testados são necessários para estender valores normativos para o eletrorretinograma.PURPOSE: To determine normative data for full-field electroretinogram (ERG

Potential of wind turbines to elicit seizures under various meteorological conditions.

Science.gov (United States)

Smedley, Andrew R D; Webb, Ann R; Wilkins, Arnold J

2010-07-01

To determine the potential risk of epileptic seizures from wind turbine shadow flicker under various meteorologic conditions. We extend a previous model to include attenuation of sunlight by the atmosphere using the libradtran radiative transfer code. Under conditions in which observers look toward the horizon with their eyes open we find that there is risk when the observer is closer than 1.2 times the total turbine height when on land, and 2.8 times the total turbine height in marine environments, the risk limited by the size of the image of the sun's disc on the retina. When looking at the ground, where the shadow of the blade is cast, observers are at risk only when at a distance turbines rotate at a rate below that at which the flicker is likely to present a risk, although there is a risk from smaller turbines that interrupt sunlight more than three times per second. For the scenarios considered, we find the risk is negligible at a distance more than about nine times the maximum height reached by the turbine blade, a distance similar to that in guidance from the United Kingdom planning authorities.

An Ergonomic Evaluation of the Illumination Level and the Management Plan to Improve the Working Environment of Nuclear Power Plants

International Nuclear Information System (INIS)

Shin, Kwang Hyeon; Lee, Yong Hee

2011-01-01

Illumination in the working environment is one of the crucial factors that affect worker's psychological status as well as the physiological condition according to each task. Sometimes it affects the results of worker's cognitive, perceptual work performance. In particular, illumination may become a triggering factor to human errors in visual tasks due to visual fatigue through direct influence of vision in NPPs. Illumination includes several visual conditions such as uniformity factor, light distribution, glare, SPD (Surge Protector Device), flicker, illumination system, daylight and window control, in addition to the simple physical aspects of illumination and luminance. These conditions may affect operators' visibility and disillusion level, cause stress, attention, emotion, etc. and they finally affect workers' performance and errors as a result. From the many illumination conditions mentioned above, current work environment evaluation items on illumination are mainly based only on the intensity of illumination, and there is yet no systematic way with evaluation criteria for other factors such as luminance, flickering, etc. In addition, research and development on illumination emphasizes mainly the physical characteristics of illumination, and it is insufficient for the influence studies on human error or work performance that are caused by these factors

Cone responses in Usher syndrome types 1 and 2 by microvolt electroretinography.

Science.gov (United States)

Zein, Wadih M; Falsini, Benedetto; Tsilou, Ekaterina T; Turriff, Amy E; Schultz, Julie M; Friedman, Thomas B; Brewer, Carmen C; Zalewski, Christopher K; King, Kelly A; Muskett, Julie A; Rehman, Atteeq U; Morell, Robert J; Griffith, Andrew J; Sieving, Paul A

2014-11-25

Progressive decline of psychophysical cone-mediated measures has been reported in type 1 (USH1) and type 2 (USH2) Usher syndrome. Conventional cone electroretinogram (ERG) responses in USH demonstrate poor signal-to-noise ratio. We evaluated cone signals in USH1 and USH2 by recording microvolt level cycle-by-cycle (CxC) ERG. Responses of molecularly genotyped USH1 (n = 18) and USH2 (n = 24) subjects (age range, 15-69 years) were compared with those of controls (n = 12). A subset of USH1 (n = 9) and USH2 (n = 9) subjects was examined two to four times over 2 to 8 years. Photopic CxC ERG and conventional 30-Hz flicker ERG were recorded on the same visits. Usher syndrome subjects showed considerable cone flicker ERG amplitude losses and timing phase delays (P Usher subjects showed abnormal ERG response latency, but this changed less than amplitude with time. In USH syndrome, CxC ERG is more sensitive than conventional ERG and warrants consideration as an outcome measure in USH treatment trials. Copyright 2014 The Association for Research in Vision and Ophthalmology, Inc.

CH Cygni. I. Observational Evidence for a Disk-Jet Connection

Science.gov (United States)

Sokoloski, J. L.; Kenyon, S. J.

2003-02-01

We investigate the role of accretion in the production of jets in the symbiotic star CH Cygni. Assuming that the rapid stochastic optical variations in CH Cygni come from the accretion disk, as in cataclysmic variables, we use changes in this flickering to diagnose the state of the disk in 1997. At that time, CH Cygni dropped to a very low optical state, and Karovska et al. report that a radio jet was produced. For approximately 1 yr after the jet production, the amplitude of the fastest (timescale of minutes) variations was significantly reduced, although smooth, hour-timescale variations were still present. This light-curve evolution indicates that the inner disk may have been disrupted, or emission from this region suppressed, in association with the mass ejection event. We describe optical spectra that support this interpretation of the flickering changes. The simultaneous state change, jet ejection, and disk disruption suggest a comparison between CH Cygni and some black hole candidate X-ray binaries that show changes in the inner-disk radius in conjunction with discrete ejection events on a wide range of timescales (e.g., the microquasar GRS 1915+105 and XTE J1550-564).

'Quantization' of stochastic variables: description and effects on the input noise sources in a BWR

International Nuclear Information System (INIS)

Matthey, M.

1979-01-01

A set of macrostochastic and discrete variables, with Markovian properties, is used to characterize the state of a BWR, whose input noise sources are of interest. The ratio between the auto-power spectral density (APSD) of the neutron noise fluctuations and the square modulus of the transfer function (SMTF) defines 'the total input noise source' (TINS), the components of which are the different noise source corresponding to the relevant variables. A white contribution to TINS arises from the birth and death processes of neutrons in the reactor and corresponds to a 'shot noise' (SN). Non-white contributions arise from fluctuations of the neutron cross-sections caused by fuel temperature and steam content variations. These terms called 'Flicker noises' (FN) are characterized by cut-off frequencies related to time constants of reactivity feedback effects. The respective magnitudes of the shot and flicker noises depend not only on the frequency, the feedback reactivity coefficients or the power of the reactor, but also on the 'quantization' of the continuous variables introduced such as fuel temperature and steam content. The effects of this last 'quantization' on the shapes of the noise sources and their sum are presented in this paper. (author)

Legacy Bird Species at Risk Monitoring in and Around Camp Navajo and the Naval Observatory Flagstaff Station, AZ

Science.gov (United States)

2010-04-16

19th century due to a convergence of complex stressors such as overgrazing, timber harvest, drought , and fire suppression (Allen et al. 2002, Moore... pinus 16 Olive Warbler Peucedramus taeniatus 5 Plumbeous Vireo Vireo solitarius 60 Pygmy Nuthatch Sitta pygmaea 177 Red Crossbill Loxia...Dove Zenaida macroura 14 Northern Flicker Colaptes auratus 50 Pine Siskin Carduelis pinus 58 Olive-sided Flycatcher Contopus cooperi 1

Hepatic encephalopathy before and neurological complications after liver transplantation have no impact on the employment status 1 year after transplantation

OpenAIRE

Pflugrad, Henning; Tryc, Anita B; Goldbecker, Annemarie; Strassburg, Christian P; Barg-Hock, Hannelore; Klempnauer, J?rgen; Weissenborn, Karin

2017-01-01

AIM To investigate the impact of hepatic encephalopathy before orthotopic liver transplantation (OLT) and neurological complications after OLT on employment after OLT. METHODS One hundred and fourteen patients with chronic liver disease aged 18-60 years underwent neurological examination to identify neurological complications, neuropsychological tests comprising the PSE-Syndrome-Test yielding the psychometric hepatic encephalopathy score, the critical flicker frequency and the Repeatable Batt...

Long-term cycles in old Novae

International Nuclear Information System (INIS)

Shara, M.M.; Potter, M.; Shara, D.J.

1989-01-01

Three of the oldest recovered novae were monitored with a CCD camera almost nightly for six weeks. The cyclic variability reported by Della Valle and Rosino (1987) for Nova Oph 1848 is confirmed. A similar variability is also suggested for Nova Cyg 1876, though this system exhibits more random flickering than Nova Oph. No secular variability is seen in Nova Sge 1783. 12 refs

Measurement of Noise in Supercapacitors

OpenAIRE

Szewczyk Arkadiusz

2017-01-01

A developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

Measurement of Noise in Supercapacitors

Directory of Open Access Journals (Sweden)

Szewczyk Arkadiusz

2017-12-01

Full Text Available A developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

Environmental Assessment for A-29 Light Air Support (LAS) Training Beddown

Science.gov (United States)

2014-08-21

cuckoo (Coccyzus americanus), ruby-throated hummingbird (Archilochus colubris), downy woodpecker (Picoides pubescens), flicker (Colaptes aurates...extreme events. Minimal additional measures would be needed to mitigate these occurrences since the A-29 operation is temporary and would end in 2018...minimal additional measures would be needed to mitigate these occurrences since the A-29 operation is temporary and would end in 2018. 3.10.3 Alternative

Automation of Sensor Control in Uninhabited Aerial Vehicles

Science.gov (United States)

2015-07-01

were otherwise performed manually reduces workload and mitigates high workload situations. On the other hand, it has been suggested that the...that automation may help mitigate high workload (Lee, 2008) it would have been interesting if both sets of authors additionally assessed when...frames would result in the sensor view flickering between two views. In support of this, VBS2 initialisation parameters were adjusted to prevent

The X-ray cataclysmic variable 1E0643.0-1648

International Nuclear Information System (INIS)

Bailey, J.; Hough, J.H.

1981-01-01

A new simultaneous IR/optical high-speed photometer on the UK IR telescope has been used to study the recently discovered cataclysmic variable 1 E0643.0-1648. The light curve shows it to be a dwarf nova with a recurrence time scale of 15 days. Photometry obtained during the decline from an outburst showed slow flickering, with the IR and optical curves correlated with no delay. (author)

Proceedings of the Annual Symposium on Frequency Control (42nd) Held in Baltimore, Maryland on 1-3 June 1988

Science.gov (United States)

1988-06-03

to the music of popcorn noise is associated with some surface Bach and the Beatles . In particular, flicker contamination and that improved fabrication...PROCEEDINGS OF THE 42ND ANNUAL FREQUENCY CONTROL SYMPOSIUM 1988 CoSponsored by the U.S. ARMY ELECTRONICS TECHNOLOGY AND DEVICES LABORATORY and THE ...THIS DOCUMENT IS BEST QUALITY AVAILABLE. THE COPY FURNISHED TO DTIC CONTAINED A SIGNIFICANT NUMBER OF PAGES WHICH DO NOT REPRODUCE LEGIBLY. Abstracting

Environmental Assessment: Addressing Expanded Herbicide Applications and the Relocation of Dry Chemical Testing at Niagra Falls Air Reserve Station, New York

Science.gov (United States)

2011-07-01

description of their uses is provided in the following paragraphs. Roundup ProT" or Kleenup ProT". Both products are post-emergent (i.e., kills existing...cardinalis Northern flicker Colaptes auratus Northern harrier2 Circus cyaneus Northern mockingbird Mimus polyglottos Northern rough-winged swallow...and Kleenup Pro™, when used according to label directions, have no weed killing activity once in contact with the soil. Glyphosate will not move in

Test and simulation of dynamic phase compensation from Mita-Teknik A/S

Energy Technology Data Exchange (ETDEWEB)

Soerensen, P.; Iov, F.; Blaabjerg, F.; Skaarup, J.

2004-03-01

This report describes the test of a dynamic phase compensation unit for a wind turbine with directly connected induction generators. The compensation unit is based on thyristor switched capacitors, where conventional wind turbine compensations use mechanical contactors to switch the capacitors. The influence on power quality analysed, and influence on component lifetime is discussed. Besides, simulation models in Matlab/Simulink are presented, including a flicker meter model. (au)

Navigational Heads-Up Display: Will a Shipboard Augmented Electronic Navigation System Sink or Swim?

Science.gov (United States)

2015-03-01

back his orders to the conning officer before execution, with the goal of mitigating some of these issues; however, the reports and recommendations...men due to their wider FOV which increases flicker perception. (LaViola, 2000) Another significant factor that is relevant to any future study in...upcoming turn might not be immediately recognized. Therefore, we attempted to mitigate this possibility by actively alerting the subjects that a turn

Continuous Tamper-proof Logging using TPM2.0

Science.gov (United States)

2014-06-16

process each log entry. Additional hardware support could mitigate this problem. Tradeoffs between performance and security guarantees Disk write...becomes weaker as the block size increases. This problem is mitigated in protocol B by allowing offline recovery from a power failure and detection of...M.K., Isozaki, H.: Flicker : An execution infrastructure for TCB minimization. ACM SIGOPS Operating Systems Review 42(4) (2008) 315–328 24. Parno, B

Acquisition of Cooperative Small Unmanned Aerial Systems for Advancing Man Machine Interface Research

Science.gov (United States)

2016-08-24

Airborne Cross Runway Departure/Landing Scenario Figure 7 Illustration of a participant looking at the 10Hz or 15Hz flickering visual stimulus in a...Figure 5 An illustration using a formation of UAVs for Direction of Arrival (DOA) mitigation of spoofing signals Spoofer Antenna array based on a...this project is to research and develop robust and jamming-resistant receivers including advanced interference mitigation algorithms and network

Flicker noise in degenerately doped Si single crystals near the metal ...

Indian Academy of Sciences (India)

discrete Lorentzians which arise from generation-recombination process ..... and for the metallic sample α has a shallow temperature dependence. ... the gr process with activation energy «0.5 eV would imply association of the deep levels.

Block-Based Gradient Descent for Local Backlight Dimming and Flicker Reduction

DEFF Research Database (Denmark)

Burini, Nino; Mantel, Claire; Nadernejad, Ehsan

2014-01-01

Local backlight dimming technology is a two-fold improvement for LED backlit LCD screens that allows to reduce power consumption and increase visual quality. This paper presents a fast version of an iterative backlight dimming algorithm based on gradient descent search. The speed is increased...

Guiding Visual Attention in Decision Making--Verbal Instructions versus Flicker Cueing

Science.gov (United States)

Canal-Bruland, Rouwen

2009-01-01

Perceptual-cognitive processes play an important role in open, fast-paced, interceptive sports such as tennis, basketball, and soccer. Visual information processing has been shown to distinguish skilled from less skilled athletes. Research on the perceptual demands of sports performance has raised questions regarding athletes' visual information…

Macular Carotenoid Supplementation Improves Visual Performance, Sleep Quality, and Adverse Physical Symptoms in Those with High Screen Time Exposure.

Science.gov (United States)

Stringham, James M; Stringham, Nicole T; O'Brien, Kevin J

2017-06-29

The dramatic rise in the use of smartphones, tablets, and laptop computers over the past decade has raised concerns about potentially deleterious health effects of increased "screen time" (ST) and associated short-wavelength (blue) light exposure. We determined baseline associations and effects of 6 months' supplementation with the macular carotenoids (MC) lutein, zeaxanthin, and mesozeaxanthin on the blue-absorbing macular pigment (MP) and measures of sleep quality, visual performance, and physical indicators of excessive ST. Forty-eight healthy young adults with at least 6 h of daily near-field ST exposure participated in this placebo-controlled trial. Visual performance measures included contrast sensitivity, critical flicker fusion, disability glare, and photostress recovery. Physical indicators of excessive screen time and sleep quality were assessed via questionnaire. MP optical density (MPOD) was assessed via heterochromatic flicker photometry. At baseline, MPOD was correlated significantly with all visual performance measures ( p eye strain, eye fatigue, and all visual performance measures, versus placebo ( p < 0.05 for all). Increased MPOD significantly improves visual performance and, in turn, improves several undesirable physical outcomes associated with excessive ST. The improvement in sleep quality was not directly related to increases in MPOD, and may be due to systemic reduction in oxidative stress and inflammation.

Flexoelectric effect in an in-plane switching (IPS) liquid crystal cell for low-power consumption display devices.

Science.gov (United States)

Kim, Min Su; Bos, Philip J; Kim, Dong-Woo; Yang, Deng-Ke; Lee, Joong Hee; Lee, Seung Hee

2016-10-12

Technology of displaying static images in portable displays, advertising panels and price tags pursues significant reduction in power consumption and in product cost. Driving at a low-frequency electric field in fringe-field switching (FFS) mode can be one of the efficient ways to save powers of the recent portable devices, but a serious drop of image-quality, so-called image-flickering, has been found in terms of the coupling of elastic deformation to not only quadratic dielectric effect but linear flexoelectric effect. Despite of the urgent requirement of solving the issue, understanding of such a phenomenon is yet vague. Here, we thoroughly analyze and firstly report the flexoelectric effect in in-plane switching (IPS) liquid crystal cell. The effect takes place on the area above electrodes due to splay and bend deformations of nematic liquid crystal along oblique electric fields, so that the obvious spatial shift of the optical transmittance is experimentally observed and is clearly demonstrated based on the relation between direction of flexoelectric polarization and electric field polarity. In addition, we report that the IPS mode has inherent characteristics to solve the image-flickering issue in the low-power consumption display in terms of the physical property of liquid crystal material and the electrode structure.

Vision-related quality of life after transsphenoidal surgery for pituitary adenoma.

Science.gov (United States)

Okamoto, Yoshifumi; Okamoto, Fumiki; Yamada, Shozo; Honda, Maiko; Hiraoka, Takahiro; Oshika, Tetsuro

2010-07-01

PURPOSE. To use the 25-item National Eye Institute Visual Function Questionnaire (VFQ-25) to evaluate vision-related quality of life (VR-QOL) in patients with pituitary adenoma who undergo transsphenoidal surgery. METHODS. The VFQ-25 was self-administered by 74 patients with pituitary adenoma before and 3 months after surgery. Pre- and postoperative clinical data were collected, including age, sex, tumor type and size, logarithm of minimum angle of resolution best corrected visual acuity (logMAR BCVA), critical flicker fusion frequency, static perimetry scores (mean deviation [MD] and corrected pattern SD [CPSD]), duration of ocular symptoms, and number of systemic comorbidities. RESULTS. Seventy-four patients with a mean age of 48.2 years were studied. Transsphenoidal surgery for pituitary adenoma significantly improved logMAR BCVA and critical fusion flicker frequency in the worse-seeing eye and MD and CPSD scores in both the better- and worse-seeing eyes (P transsphenoidal surgery can dramatically improve VR-QOL in pituitary adenoma and that the preoperative VFQ-25 composite score and visual field disturbance in the better-seeing eye are particularly important predictors associated with the postoperative VR-QOL. The use of VFQ-25 provides a more comprehensive overview of the effectiveness of transsphenoidal surgery.

Nanoscale MOS devices: device parameter fluctuations and low-frequency noise (Invited Paper)

Science.gov (United States)

Wong, Hei; Iwai, Hiroshi; Liou, J. J.

2005-05-01

It is well-known in conventional MOS transistors that the low-frequency noise or flicker noise is mainly contributed by the trapping-detrapping events in the gate oxide and the mobility fluctuation in the surface channel. In nanoscale MOS transistors, the number of trapping-detrapping events becomes less important because of the large direct tunneling current through the ultrathin gate dielectric which reduces the probability of trapping-detrapping and the level of leakage current fluctuation. Other noise sources become more significant in nanoscale devices. The source and drain resistance noises have greater impact on the drain current noise. Significant contribution of the parasitic bipolar transistor noise in ultra-short channel and channel mobility fluctuation to the channel noise are observed. The channel mobility fluctuation in nanoscale devices could be due to the local composition fluctuation of the gate dielectric material which gives rise to the permittivity fluctuation along the channel and results in gigantic channel potential fluctuation. On the other hand, the statistical variations of the device parameters across the wafer would cause the noise measurements less accurate which will be a challenge for the applicability of analytical flicker noise model as a process or device evaluation tool for nanoscale devices. Some measures for circumventing these difficulties are proposed.

Analysis on frequency response of trans-impedance amplifier (TIA) for signal-to-noise ratio (SNR) enhancement in optical signal detection system using lock-in amplifier (LIA)

Science.gov (United States)

Kim, Ji-Hoon; Jeon, Su-Jin; Ji, Myung-Gi; Park, Jun-Hee; Choi, Young-Wan

2017-02-01

Lock-in amplifier (LIA) has been widely used in optical signal detection systems because it can measure small signal under high noise level. Generally, The LIA used in optical signal detection system is composed of transimpedance amplifier (TIA), phase sensitive detector (PSD) and low pass filter (LPF). But commercial LIA using LPF is affected by flicker noise. To avoid flicker noise, there is 2ω detection LIA using BPF. To improve the dynamic reserve (DR) of the 2ω LIA, the signal to noise ratio (SNR) of the TIA should be improved. According to the analysis of frequency response of the TIA, the noise gain can be minimized by proper choices of input capacitor (Ci) and feed-back network in the TIA in a specific frequency range. In this work, we have studied how the SNR of the TIA can be improved by a proper choice of frequency range. We have analyzed the way to control this frequency range through the change of passive component in the TIA. The result shows that the variance of the passive component in the TIA can change the specific frequency range where the noise gain is minimized in the uniform gain region of the TIA.

Double layers above the aurora

International Nuclear Information System (INIS)

Temerin, M.; Mozer, F.S.

1987-01-01

Two different kinds of double layers were found in association with auroral precipitation. One of these is the so-called electrostatic shock, which is oriented at an oblique angle to the magnetic field in such a way that the perpendicular electric field is much larger than the parallel electric field. This type of double layer is often found at the edges of regions of upflowing ion beams and the direction of the electric fields in the shock points toward the ion beam. The potential drop through the shock can be several kV and is comparable to the total potential needed to produce auroral acceleration. Instabilities associated with the shock may generate obliquely propagating Alfven waves, which may accelerate electrons to produce flickering auroras. The flickering aurora provides evidence that the electrostatic shock may have large temporal fluctuations. The other kind of double layer is the small-amplitude double layer found in regions of upward flowing in beams, often in association with electrostatic ion cyclotron waves. The parallel and perpendicular electric fields in these structures are comparable in magnitude. The associated potentials are a few eV. Since many such double layers are found in regions of upward flowing ion beams, the combined potential drop through a set of these double layers can be substantial

An Ergonomic Evaluation of the Illumination Level and the Management Plan to Improve the Working Environment of Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Shin, Kwang Hyeon; Lee, Yong Hee [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

2011-10-15

Illumination in the working environment is one of the crucial factors that affect worker's psychological status as well as the physiological condition according to each task. Sometimes it affects the results of worker's cognitive, perceptual work performance. In particular, illumination may become a triggering factor to human errors in visual tasks due to visual fatigue through direct influence of vision in NPPs. Illumination includes several visual conditions such as uniformity factor, light distribution, glare, SPD (Surge Protector Device), flicker, illumination system, daylight and window control, in addition to the simple physical aspects of illumination and luminance. These conditions may affect operators' visibility and disillusion level, cause stress, attention, emotion, etc. and they finally affect workers' performance and errors as a result. From the many illumination conditions mentioned above, current work environment evaluation items on illumination are mainly based only on the intensity of illumination, and there is yet no systematic way with evaluation criteria for other factors such as luminance, flickering, etc. In addition, research and development on illumination emphasizes mainly the physical characteristics of illumination, and it is insufficient for the influence studies on human error or work performance that are caused by these factors

Compensation of the skin effect in low-frequency potential drop measurements

OpenAIRE

Corcoran, J; Nagy, PB

2016-01-01

Potential drop measurements are routinely used in the non-destructive evaluation of component integrity. Potential drop measurements use either direct current (DC) or alternating current (AC), the latter will have superior noise performance due to the ability to perform phase sensitive detection and the reduction of flicker noise. AC measurements are however subject to the skin effect where the current is electromagnetically constricted to the surface of the component. Unfortunately, the skin...

7T Magnetization Transfer and Chemical Exchange Saturation Transfer MRI of Cortical Gray Matter: Can We Detect Neurochemical and Macromolecular Abnormalities

Science.gov (United States)

2015-10-01

mitigate B1 inhomogeneity further (which can be problematic for segmentation), we divided the qMT- weighted images obtained at the 10th and 14th inversion...where lesions were classified as GM, we wanted to mitigate the impact that this could have on looking at the GM across patient cohorts. Thus, we...planning/executive function • "Black Box” (choice reaction time, critical flicker fusion; pre-scan and post-scan): measures processing speed/reaction

Turning Point: Operation Allied Force and the Allure of Air Power

Science.gov (United States)

2014-06-13

Air Force Base in Nevada, from “a windowless bunker, lit by constantly flickering computer screens,” a Predator drone operator zoomed in on the...how the Army would mitigate risks to the Apaches by using artillery to suppress Serb air defenses before the Apaches went on their deep strike...conflict.” 162Clark, Waging Modern War, 236-7. 163Drozdiak, A22. 164To mitigate alliance member concerns, NATO did not officially refer to

SIGAR Quarterly Report to the United States Congress

Science.gov (United States)

2016-07-30

unheated these days [winter 2015– 2016], or have flickering lights and technical devices that do not work due to poor voltage.”43 As noted, however...challenges we find, making recommendations wherever we can to address these problems and mitigate the risk to taxpayer funds, and even arresting...DOD further noted that oversight will continue to be a chal- lenge until security in Afghanistan improves and suggested steps to mitigate the risks

Division Level Social Media

Science.gov (United States)

2015-06-12

the lines of effort (LOE), goal, and MOE.8 The MOH story was distributed through the following social media sites: Flicker , Facebook, Twitter, and a...and shares to save a follower’s time for more popular posts or paid advertisements. One way to mitigate paying for advertising is access to better...related items, which hinders analysis for growth and ways to mitigate dwindling organic reach. Lastly, better expectation 60 management is critical

7T Magnetization Transfer and Chemical Exchange Saturation Transfer MRI of Cortical Gray Matter: Can We Detect Neurochemical and Macromolecular Abnormalities?

Science.gov (United States)

2014-10-21

measures working memory • Trail making test (both A and B): measures planning/executive function • "Black Box” (choice reaction time, critical flicker ...associated with SIR imaging. The former of these was mitigated by developing a novel B+ and !1B insensitive in- version composite pulse (Fig. 2) and...employing a low-flip angle TFE readout; the latter was mitigated by the efficiency of the TFE readout along with additional protocol optimization

Environmental Assessment (EA): Proposed Emergency Power Unit Overhaul Complex at Little Mountain Test Annex, Utah

Science.gov (United States)

2014-03-14

association with World War II. However, it has been previously mitigated through a memorandum of agreement between the USAF and the Utah SHPO, signed in...goldfinch Carduelis tristis T U * House sparrow Passer domesticus R C *‡ Mountain bluebird Sialia currucoides S U * Northern flicker Colaptes...been mitigated . This information is provided to assist with Section 106 responsibilities as per §36CFR800. If you have questions, please contact me at

A Physiological and Psychometric Evaluation of Human Subconscious Visual Response and Its Application in Health Promoting Lighting

Science.gov (United States)

Vartanian, Garen V.

Subconscious vision is a recent focus of the vision science community, brought on by the discovery of a previously unknown photoreceptor in the retina dedicated to driving non-image-forming responses, intrinsically photosensitive retinal ganglion cells (ipRGCs). In addition to accepting inputs from rod and cone photoreceptors, ipRGCs contain their own photopigment, melanopsin, and are considered true photoreceptors. ipRGCs drive various non-image-forming photoresponses, including circadian photoentrainment, melatonin suppression, and pupil constriction. In order to understand more about ipRGC function in humans, we studied its sensitivity to light stimuli in the evening and day. First, we measured the sensitivity threshold of melatonin suppression at night. Using a protocol that enhances data precision, we have found the threshold for human melatonin suppression to be two orders of magnitude lower than previously reported. This finding has far-reaching implications since there is mounting evidence that nocturnal activation of the circadian system can be harmful. Paradoxically, ipRGCs are understimulated during the day. Optimizing daytime non-image-forming photostimulation has health benefits, such as increased alertness, faster reaction times, better sleep quality, and treatment of depression. In order to enhance ipRGC excitation, we aimed to circumvent adaptation (i.e. desensitization) of the photoresponse by using flickering instead of steady light. We find that properly timed flickering light enhances pupillary light reflex significantly when compared to steady light with 9-fold more energy density. Employing our findings, a new form of LED light is proposed to enhance subconscious visual responses at a typical indoor illuminance level. Using the silent substitution technique, a melanopsin-selective flicker is introduced into the light. A linear optimization algorithm is used to maximize the contrast of the subconscious, melanopsin-based response function while

Phase noise in RF and microwave amplifiers.

Science.gov (United States)

Boudot, Rodolphe; Rubiola, Enrico

2012-12-01

Understanding amplifier phase noise is a critical issue in many fields of engineering and physics, such as oscillators, frequency synthesis, telecommunication, radar, and spectroscopy; in the emerging domain of microwave photonics; and in exotic fields, such as radio astronomy, particle accelerators, etc. Focusing on the two main types of base noise in amplifiers, white and flicker, the power spectral density of the random phase φ(t) is Sφ(f) = b(0) + b(-1)/f. White phase noise results from adding white noise to the RF spectrum in the carrier region. For a given RF noise level, b(0) is proportional to the reciprocal of the carrier power P(0). By contrast, flicker results from a near-dc 1/f noise-present in all electronic devices-which modulates the carrier through some parametric effect in the semiconductor. Thus, b(-1) is a parameter of the amplifier, constant in a wide range of P(0). The consequences are the following: Connecting m equal amplifiers in parallel, b(-1) is 1/m times that of one device. Cascading m equal amplifiers, b(-1) is m times that of one amplifier. Recirculating the signal in an amplifier so that the gain increases by a power of m (a factor of m in decibels) as a result of positive feedback (regeneration), we find that b(-1) is m(2) times that of the amplifier alone. The feedforward amplifier exhibits extremely low b(-1) because the carrier is ideally nulled at the input of its internal error amplifier. Starting with an extensive review of the literature, this article introduces a system-oriented model which describes the phase flickering. Several amplifier architectures (cascaded, parallel, etc.) are analyzed systematically, deriving the phase noise from the general model. There follow numerous measurements of amplifiers using different technologies, including some old samples, and in a wide frequency range (HF to microwaves), which validate the theory. In turn, theory and results provide design guidelines and give suggestions for CAD and

Noise frame duration, masking potency and whiteness of temporal noise

OpenAIRE

Kukkonen, Helja; Rovamo, Jyrki; Donner, Kristian; Tammikallio, Marja; Raninen, Antii

2002-01-01

PURPOSE. Because of the limited contrast range, increasing the duration of the noise frame is often the only option for increasing the masking potency of external, white temporal noise. This, however, reduces the high-frequency cutoff beyond which noise is no longer white. This study was conducted to determine the longest noise frame duration that produces the strongest masking effect and still mimics white noise on the detection of sinusoidal flicker. \\ud \\ud METHODS. Contrast energy thresho...

Characterization of Nanowire Photodetectors

Science.gov (United States)

2016-11-28

characterization system and picosecond pulsed laser source will be used to provide deeper insight into the fast charge carrier dynamics in the GaAsSb and...value of the current fluctuations for a particular frequency, f is the effective measurement bandwidth at the discrete frequency point, and IDS is...GaAsSb CS nanowires. The best fit of the spectra with the simulation carried out using Matlab revealed flicker noise at lower frequency having 1/f

CALiPER Exploratory Study. Recessed Troffer Lighting

Energy Technology Data Exchange (ETDEWEB)

Miller, N. J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Royer, M. P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Poplawski, M. E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

2013-03-01

This CALiPER study examines the problems and benefits likely to be encountered with LED products intended to replace linear fluorescent lamps. LED dedicated troffers, replacement tubes, and non-tube retrofit kits were evaluated against fluorescent benchmark troffers in a simulated office space for photometric distribution, uniformity of light on the task surface, suitability of light output, flicker, dimming performance, color quality, power quality, safety and certification issues, ease of installation, energy efficiency, and life-cycle cost.

Entropy and Self-Organization - An Open System Approach to the Origins of Homeland Security Threats

Science.gov (United States)

2015-06-01

to properly understand homeland security threats and their origin directly impacts our ability to prevent or mitigate these threats. “Homeland...of new cognitive approaches or policy tools to eliminate or mitigate homeland security threats, perhaps even at the level of their root causes. A key...to self-similar ‘fractal’ structure. The frequency spectrum of 1/f noise or flicker noise with a power-law spectrum S (f) ≈ f⁻β.” Bak, Tang, and

Maritime Evaluation of Aerosol Fire Knock Down Tools. Part 2: Toxicity and Corrosion Potential

Science.gov (United States)

2014-02-01

as fire is suppressed) 8 A low flame flicker was seen as the door was opened; however, the fire did extinguish shortly thereafter. 26 the repeat...clean and d) in which the CD was also exposed to diesel fire gases, indicated that wiping the surface of the disc might mitigate the damage somewhat...outlined in red in the images. Results indicate that wiping the surface of the disc might mitigate the damage somewhat; however, in all cases, pitting

Crystalline lens thickness determines the perceived chromatic difference in magnification.

Science.gov (United States)

Chen, Yun; Schaeffel, Frank

2014-03-01

Since the origin of the high interindividual variability of the chromatic difference in retinal image magnification (CDM) in the human eye is not well understood, optical parameters that might determine its magnitude were studied in 21 healthy subjects with ages ranging from 21 to 58 years. Two psychophysical procedures were used to quantify CDM. They produced highly correlated results. First, a red and a blue square, presented on a black screen, had to be matched in size by the subjects with their right eyes. Second, a filled red and blue square, flickering on top of each other at 2 Hz, had to be adjusted in perceived brightness and then in size to minimize the impression of flicker. CDM varied widely among subjects from 0.0% to 3.6%. Biometric ocular parameters were measured with low coherence interferometry and crystalline lens tilt and decentration with a custom-built Purkinjemeter. Correlations were studied between CDM and corneal power, anterior chamber depth, lens thickness, lens tilt and lens decentration, and vitreous chamber depths. Lens thickness was found significantly correlated with CDM and accounted for 64% of its variance. Vertical lens tilt and decentration were also significantly correlated. It was also found that CDM increased by 3.5% per year, and part of this change can be attributed to the age-related increase in lens thickness.

Effect of removing the common mode errors on linear regression analysis of noise amplitudes in position time series of a regional GPS network & a case study of GPS stations in Southern California

Science.gov (United States)

Jiang, Weiping; Ma, Jun; Li, Zhao; Zhou, Xiaohui; Zhou, Boye

2018-05-01

The analysis of the correlations between the noise in different components of GPS stations has positive significance to those trying to obtain more accurate uncertainty of velocity with respect to station motion. Previous research into noise in GPS position time series focused mainly on single component evaluation, which affects the acquisition of precise station positions, the velocity field, and its uncertainty. In this study, before and after removing the common-mode error (CME), we performed one-dimensional linear regression analysis of the noise amplitude vectors in different components of 126 GPS stations with a combination of white noise, flicker noise, and random walking noise in Southern California. The results show that, on the one hand, there are above-moderate degrees of correlation between the white noise amplitude vectors in all components of the stations before and after removal of the CME, while the correlations between flicker noise amplitude vectors in horizontal and vertical components are enhanced from un-correlated to moderately correlated by removing the CME. On the other hand, the significance tests show that, all of the obtained linear regression equations, which represent a unique function of the noise amplitude in any two components, are of practical value after removing the CME. According to the noise amplitude estimates in two components and the linear regression equations, more accurate noise amplitudes can be acquired in the two components.

Dynamics of Woodpecker – Common Starling interactions: a comparison of Old World and New World species and populations

Directory of Open Access Journals (Sweden)

Jackson Jerome A.

2016-06-01

Full Text Available Woodpecker species whose cavities are most usurped by Common Starlings (Sturnus vulgaris are widespread and generalists in their use of habitats. These include primarily woodpeckers that are similar in size to or slightly larger than the starling - such as the Great-spotted Woodpecker (Dendrocopos major of Eurasia and the Northern Flicker (Colaptes auratus and Red-bellied (Melanerpes carolinus and Red-headed (M. erythrocephalus Woodpeckers of North America. Usurpation occurs primarily in human-dominated urban, suburban and exurban habitats with pastures, sports fields and other open areas that serve as prime feeding habitats for starlings. Starlings prefer high, more exposed cavities with a minimal entrance diameter relative to their body size. Usurpation success depends on timing - optimally just as a cavity is completed and before egg-laying by the woodpeckers. Starlings likely reduce woodpecker populations in more open, human-dominated habitats. Woodpecker habitat losses and fragmentation are more serious problems that enhance habitat quality for starlings and reduce habitat quality for most woodpeckers. The only woodpeckers that might become in danger of extinction as a primary result of starling cavity usurpation are likely island species with small populations. Conservation of rare species limited to islands, such as Fernandina’s Flicker (Colaptes fernandinae of Cuba, may depend on our ability to prevent the establishment of the Common Starling or other aggressive cavity competitors on their island.

Motion-Dependent Filling-In of Spatiotemporal Information at the Blind Spot.

Science.gov (United States)

Maus, Gerrit W; Whitney, David

2016-01-01

We usually do not notice the blind spot, a receptor-free region on the retina. Stimuli extending through the blind spot appear filled in. However, if an object does not reach through but ends in the blind spot, it is perceived as "cut off" at the boundary. Here we show that even when there is no corresponding stimulation at opposing edges of the blind spot, well known motion-induced position shifts also extend into the blind spot and elicit a dynamic filling-in process that allows spatial structure to be extrapolated into the blind spot. We presented observers with sinusoidal gratings that drifted into or out of the blind spot, or flickered in counterphase. Gratings moving into the blind spot were perceived to be longer than those moving out of the blind spot or flickering, revealing motion-dependent filling-in. Further, observers could perceive more of a grating's spatial structure inside the blind spot than would be predicted from simple filling-in of luminance information from the blind spot edge. This is evidence for a dynamic filling-in process that uses spatiotemporal information from the motion system to extrapolate visual percepts into the scotoma of the blind spot. Our findings also provide further support for the notion that an explicit spatial shift of topographic representations contributes to motion-induced position illusions.

Dependence of diameters and oxygen saturation of retinal vessels on visual field damage and age in primary open-angle glaucoma.

Science.gov (United States)

Ramm, Lisa; Jentsch, Susanne; Peters, Sven; Sauer, Lydia; Augsten, Regine; Hammer, Martin

2016-05-01

To investigate the interrelationship between the oxygen supply of the retina and its regulation with the severity of primary open-angle glaucoma (POAG). Central retinal artery (CRAE) and vein (CRVE) diameters and oxygen saturation of peripapillary retinal vessels in 41 patients suffering from POAG (64.1 ± 12.9 years) and 40 healthy volunteers (63.6 ± 14.1 years) were measured using the retinal vessel analyzer. All measures were taken before and during flicker light stimulation. The mean retinal nerve fiber layer thickness (RNFLT) was determined by OCT and the visual field mean defect (MD) was identified using perimetry. In glaucoma patients, CRAE (r = -0.48 p = 0.002) and CRVE (r = -0.394 p = 0.014) at baseline were inversely related to MD, while arterial and venous oxygen saturation showed no significant dependence on the severity of the damage. However, the flicker light-induced change in arterio-venous difference in oxygen saturation was correlated with the MD (r = 0.358 p = 0.027). The diameters of arteries and veins at baseline decreased with reduction of the mean RNFLT (arteries: r = 0.718 p field loss, may be explained by a reduction of the retinal metabolic demand with progressive loss of neuronal tissue in glaucoma. © 2015 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

Retinopathy in an obesity WHO III cohort: prevalence and risk factors.

Science.gov (United States)

Mattern, Juri; Lammert, Alexander; Otto, Mirko; Hammes, Hans-Peter

2017-11-01

To assess retinopathy and its risk factors in an obesity WHO III cohort. In the Mannheim Obesity Study , 277 subjects with obesity WHO III aged 18-64 years were examined in a cross-sectional approach. Screening for retinopathy was performed using 3-field retinal photography. Endothelial function was assessed using arteriole-to-venule ratio and flicker light analysis. Subjects with and without retinopathy were analysed for anthropometry, metabolic, vascular and renal parameters. Retinopathy was found in 18 of the 277 subjects (6.5%). Prevalence of retinopathy was 16.7% in subjects with and 3.4% in subjects without diabetes mellitus. Between subjects with and without retinopathy there were significant differences in diabetes prevalence (61.1% vs 21.7%, pretinopathy (OR 8.3, p=0.049, 95% CI 1.01 to 67.49), whereas risk for retinopathy decreased by nearly 50% (OR 0.54, p=0.032, 95% CI 0.30 to 0.95) with each percentage increase in venous dilatation in response to flicker light. Retinopathy prevalence in our obesity WHO III cohort is low. Presence of diabetes mellitus is the most important risk factor for retinopathy. Preserved venular function indicates protection from retinopathy. NCT00770276, Results. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Pulse on pulse: modulation and signification in Rafael Lozano-Hemmer's Pulse Room

Directory of Open Access Journals (Sweden)

Merete Carlson

2012-06-01

Full Text Available This article investigates the relation between signifying processes and non-signifying material dynamism in the installation Pulse Room (2006 by Mexican Canadian artist Rafael Lozano-Hemmer. In Pulse Room the sense of pulse is ambiguous. Biorhythms are transmitted from the pulsing energy of the visitor's beating heart to the flashing of a fragile light bulb, thereby transforming each light bulb into a register of individual life. But at the same time the flashing light bulbs together produce a chaotically flickering light environment composed by various layers of repetitive rhythms, a vibrant and pulsating “room”. Hence, the visitor in Pulse Room is invited into a complex scenario that continuously oscillates between various aspects of signification (the light bulbs representing individual lives; the pulse itself as the symbolic “rhythm of life” and instants of pure material processuality (flickering light bulbs; polyrhythmic layers. Taking our point of departure in a discussion of Gilles Deleuze's concepts of modulation and signaletic material in relation to electronic media, we examine how the complex orchestration of pulsation between signification and material modulation produces a multilayered sense of time and space that is central to the sensory experience of Pulse Room as a whole. Pulse Room is, at the very same time, a relational subject–object intimacy and an all-encompassing immersive environment modulating continuously in real space-time.

A Longitudinal Follow-Up Study of Saffron Supplementation in Early Age-Related Macular Degeneration: Sustained Benefits to Central Retinal Function

Directory of Open Access Journals (Sweden)

M. Piccardi

2012-01-01

Full Text Available Objectives. In a previous randomized clinical trial (Falsini et al. (2010, it was shown that short-term Saffron supplementation improves retinal flicker sensitivity in early age-related macular degeneration (AMD. The aim of this study was to evaluate whether the observed functional benefits from Saffron supplementation may extend over a longer follow-up duration. Design. Longitudinal, interventional open-label study. Setting. Outpatient ophthalmology setting. Participants. Twenty-nine early AMD patients (age range: 55–85 years with a baseline visual acuity >0.3. Intervention. Saffron oral supplementation (20 mg/day over an average period of treatment of 14 (±2 months. Measurements. Clinical examination and focal-electroretinogram-(fERG- derived macular (18° flicker sensitivity estimate (Falsini et al. (2010 every three months over a followup of 14 (±2 months. Retinal sensitivity, the reciprocal value of the estimated fERG amplitude threshold, was the main outcome measure. Results. After three months of supplementation, mean fERG sensitivity improved by 0.3 log units compared to baseline values (P<0.01, and mean visual acuity improved by two Snellen lines compared to baseline values (0.75 to 0.9, P<0.01. These changes remained stable over the follow-up period. Conclusion. These results indicate that in early AMD Saffron supplementation induces macular function improvements from baseline that are extended over a long-term followup.

Photoreceptor atrophy in acute zonal occult outer retinopathy

DEFF Research Database (Denmark)

Zibrandtsen, N.; Munch, I.C.; Klemp, K.

2008-01-01

appearance were examined using optical coherence tomography (OCT), automated perimetry and electroretinography (ERG). RESULTS: Both patients demonstrated photoreceptor atrophy corresponding to partial or complete scotomata with reduced or extinct electroretinographic responses. Attenuation or complete loss...... of all the segments composing the photoreceptor layer was found by OCT. Full-field ERG revealed affection of the 30 Hz flicker responses and subnormal photopic responses in both patients and subnormal scotopic responses in case 1. Multifocal electroretinography (mERG) revealed localized outer retinal...

Photoreceptor atrophy in acute zonal occult outer retinopathy

DEFF Research Database (Denmark)

Zibrandtsen, N.; Munch, I.C.; Klemp, K.

2008-01-01

examined using optical coherence tomography (OCT), automated perimetry and electroretinography (ERG). Both patients demonstrated photoreceptor atrophy corresponding to partial or complete scotomata with reduced or extinct electroretinographic responses. Attenuation or complete loss of all the segments...... composing the photoreceptor layer was found by OCT. Full-field ERG revealed affection of the 30 Hz flicker responses and subnormal photopic responses in both patients and subnormal scotopic responses in case 1. Multifocal electroretinography (mERG) revealed localized outer retinal dysfunction. The field...

Acute and subchronic effects of Org 2305 and diazepam on psychomotor performance in man.

OpenAIRE

Mattila, M J; Koski, J; Strömberg, C

1987-01-01

Three doses (15, 30 and 60 mg) of Org 2305 (O 15, O 30 and O 60 respectively), a novel anxiolytic drug chemically related to mianserin, were compared with placebo and 15 mg diazepam (DZ) on human psychomotor performance in a double-blind, cross-over study with 15 healthy volunteers. Objective measurements (choice reaction, tracking, flicker fusion, Maddox wing, digit symbol substitution, memory recall) and subjective assessments (visual analogue scales) were done at baseline and 2 and 13 h af...

Flexoelectric effect in an in-plane switching (IPS) liquid crystal cell for low-power consumption display devices

OpenAIRE

Kim, Min Su; Bos, Philip J.; Kim, Dong-Woo; Yang, Deng-Ke; Lee, Joong Hee; Lee, Seung Hee

2016-01-01

Technology of displaying static images in portable displays, advertising panels and price tags pursues significant reduction in power consumption and in product cost. Driving at a low-frequency electric field in fringe-field switching (FFS) mode can be one of the efficient ways to save powers of the recent portable devices, but a serious drop of image-quality, so-called image-flickering, has been found in terms of the coupling of elastic deformation to not only quadratic dielectric effect but...

Midwifery basics. Antenatal care--health in pregnancy.

Science.gov (United States)

Baston, Helen

2003-01-01

Joanna is now 20 weeks pregnant. She has been well, although rather nauseous at times, but this is now less frequent. Her abdomen is beginning to expand, but she is at a stage where it isn't obvious that she is pregnant, and she just feels fat. She has felt the tiniest flicker of what she thinks are fetal movements, but is not quite sure. Louis, her partner, can not feel anything and finds it all rather hard to conceptualise.

Limits to the Usability of Iconic Memory

OpenAIRE

Ronald A. Rensink

2014-01-01

Human vision briefly retains a trace of a stimulus after it disappears. This trace—iconic memory—is often believed to be a surrogate for the original stimulus, a representational structure that can be used as if the original stimulus were still present. To investigate its nature, a flicker-search paradigm was developed that relied upon a full scan (rather than partial report) of its contents. Results show that for visual search it can indeed act as a surrogate, with little cost for alterna...

Dynamic bifurcations on financial markets

International Nuclear Information System (INIS)

Kozłowska, M.; Denys, M.; Wiliński, M.; Link, G.; Gubiec, T.; Werner, T.R.; Kutner, R.; Struzik, Z.R.

2016-01-01

We provide evidence that catastrophic bifurcation breakdowns or transitions, preceded by early warning signs such as flickering phenomena, are present on notoriously unpredictable financial markets. For this we construct robust indicators of catastrophic dynamical slowing down and apply these to identify hallmarks of dynamical catastrophic bifurcation transitions. This is done using daily closing index records for the representative examples of financial markets of small and mid to large capitalisations experiencing a speculative bubble induced by the worldwide financial crisis of 2007-08.

Achieving Peace in Northern Mali: Past Agreements, Local Conflicts, and the Prospects for a Durable Settlement

Science.gov (United States)

2015-01-01

conflict- mitigation mechanisms used in northern Mali—such as political agreements and integration of former militants into security forces—as well as...21. 24 Keita, 2002, p. 23. 25 Sophie Boukhari, “Mali: A Flickering Flame,” UNESCO Courier, Vol. 53, No. 1, January 2000, pp. 26–28, p. 27. 26 Susanna...state do not have the level of tensions they had under Tandja.65 Issoufou also took measures to mitigate the consequences that the Libyan crisis had

CSI 2264: Simultaneous Optical and Infrared Light Curves of Young Disk-Bearing Stars in NGC 2264 With CoRoT and Spitzer-Evidence For Multiple Origins of Variability

Science.gov (United States)

2014-03-13

2005). the first position, two exposures were acquired with an 8" dither to mitigate any detector artifacts or cosmic-ray hits. Total frame time...with a ŕ/ f" trend in amplitude; two examples are provided in Figure 17. This is in contrast to typical red or " flicker " noise, which follows a 1...transitions between staring and mapping photometry. Following pixel-phase mitigation , we selected the set of ~280 by-BCD staring points lying within 1.2

EUV FLICKERING OF SOLAR CORONAL LOOPS: A NEW DIAGNOSTIC OF CORONAL HEATING

Energy Technology Data Exchange (ETDEWEB)

Tajfirouze, E.; Reale, F.; Peres, G. [Dipartimento di Fisica e Chimica, Università di Palermo, Piazza del Parlamento 1, I-90134 (Italy); Testa, P., E-mail: reale@astropa.unipa.it [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

2016-02-01

A previous work of ours found the best agreement between EUV light curves observed in an active region core (with evidence of super-hot plasma) and those predicted from a model with a random combination of many pulse-heated strands with a power-law energy distribution. We extend that work by including spatially resolved strand modeling and by studying the evolution of emission along the loops in the EUV 94 Å and 335 Å channels of the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Using the best parameters of the previous work as the input of the present one, we find that the amplitude of the random fluctuations driven by the random heat pulses increases from the bottom to the top of the loop in the 94 Å channel and from the top to the bottom in the 335 Å channel. This prediction is confirmed by the observation of a set of aligned neighboring pixels along a bright arc of an active region core. Maps of pixel fluctuations may therefore provide easy diagnostics of nanoflaring regions.

Ultraviolet continuum variability and visual flickering in the peculiar object MWC 560

Science.gov (United States)

Michalitsianos, A. G.; Perez, M.; Shore, S. N.; Maran, S. P.; Karovska, M.; Sonneborn, G.; Webb, J. R.; Barnes, Thomas G., III; Frueh, Marian L.; Oliversen, R. J.

1993-01-01

High-speed U-band photometry of the peculiar emission object MWC 560 obtained with the ground-based instrumentation, and V-band photometry obtained with the International Ultraviolet Explorer-Fine Error Sensor indicates irregular brightness variations are quasi-periodic. Multiple peaks of relative brightness power indicate statistically significant quasi periods existing in a range of 3-35 minutes, that are superposed on slower hourly varying components. We present a preliminary model that explains the minute and hourly time-scale variations in MWC 560 in terms of a velocity-shear instability that arises because a white dwarf magnetosphere impinges on an accretion disk. We also find evidence for Fe II multiplet pseudocontinuum absorption opacity in far-UV spectra of CH Cygni which is also present in MWC 560. Both CH Cyg and MWC 560 may be in an evolutionary stage that is characterized by strong UV continuum opacity which changes significantly during outburst, occurring before they permanently enter the symbiotic nebular emission phase.

The FNS-based analyzing the EEG to diagnose the bipolar affective disorder

International Nuclear Information System (INIS)

Panischev, Yu; Panischeva, S N; Demin, S A

2015-01-01

Here we demonstrate a capability of method based on the Flicker-Noise Spectroscopy (FNS) in analyzing the manifestation bipolar affective disorder (BAD) in EEG. Generally EEG from BAD patient does not show the visual differences from healthy EEG. Analyzing the behavior of FNS-parameters and the structure of 3D-cross correlators allows to discover the differential characteristics of BAD. The cerebral cortex electric activity of BAD patients have a specific collective dynamics and configuration of the FNS-characteristics in comparison with healthy subjects. (paper)

Sound card based digital correlation detection of weak photoelectrical signals

International Nuclear Information System (INIS)

Tang Guanghui; Wang Jiangcheng

2005-01-01

A simple and low-cost digital correlation method is proposed to investigate weak photoelectrical signals, using a high-speed photodiode as detector, which is directly connected to a programmably triggered sound card analogue-to-digital converter and a personal computer. Two testing experiments, autocorrelation detection of weak flickering signals from a computer monitor under background of noisy outdoor stray light and cross-correlation measurement of the surface velocity of a motional tape, are performed, showing that the results are reliable and the method is easy to implement

Epilepsy provoked by television and video games: safety of 100-Hz screens.

Science.gov (United States)

Ricci, S; Vigevano, F; Manfredi, M; Kasteleijn-Nolst Trenité, D G

1998-03-01

Television (TV) and video games (VG) can provoke seizures in patients with photosensitive epilepsies. Flicker frequency is the most important factor in screen activation. We tested conventional 50-Hz versus 100-Hz monitors during TV viewing and VG playing in 30 photosensitive subjects, 23 of whom had a history of TV or VG seizures or both. Fifteen subjects' discharges were activated by 50-Hz TV; 17 by 50-Hz VG; and one by a 100-Hz screen. Thus, 100-Hz screens protect against screen activation.

La eficacia del efecto látigo en el drag flick en el hockey hierba The effectiveness of the bullwhip effect in the Drag-flick in field hockey

Directory of Open Access Journals (Sweden)

C. López de Subijana

2010-09-01

Full Text Available

El penalty córner es una de las jugadas más importantes en el hockey hierba. El drag-flick es la técnica de golpeo más eficaz en las jugadas de penalty córner (McLaughin, 1997. Los objetivos del presente estudio fueron el describir los parámetros cinemáticos del drag-flick en jugadores de nivel internacional y analizar las diferencias intergénero. La muestra fueron trece sujetos, un modelo, seis hombres y seis mujeres. El sistema de captura automático VICON registró 20 lanzamientos de cada jugador con una frecuencia de muestreo de 250 Hz. Las velocidades máximas angulares de las caderas, hombros y stick  fueron superiores  (p<0.01 en el modelo que en ambos grupos de género. Mediante la comparación estadística del modelo con ambos grupos de género se han podido determinar las claves de este gesto técnico, siendo necesario un movimiento hacia atrás del stick (efecto látigo antes de la aceleración de caderas y hombros, para terminar el gesto con la máxima aceleración del stick.
Palabras Clave: Biomecánica, drag-flick, hockey hierba, cinemática

The penalty corner is one of the most important goal plays in field hockey. The drag-flick is more efficient than other techniques when playing a penalty corner. The aims of this study were to describe the kinematics of international field hockey players during the drag-flick and to analyse gender differences. Thirteen participants, one male drag-flicker, six males and six females participated in the study. VICON optoelectronic system measured the kinematic parameters from the drag-flick with six cameras sampling at 250 Hz. Twenty trials were captured from each subject. Ball velocity at release, hips maximum angular velocity, stick minimum and maximum angular velocities were higher (p<0.01 in the drag-flicker than in both gender groups. Comparing with the drag-flicker we have found the cues of the skill, being necessary a

The impact of electrode materials on 1/f noise in piezoelectric AlN contour mode resonators

Science.gov (United States)

Kim, Hoe Joon; Jung, Soon In; Segovia-Fernandez, Jeronimo; Piazza, Gianluca

2018-05-01

This paper presents a detailed analysis on the impact of electrode materials and dimensions on flicker frequency (1/f) noise in piezoelectric aluminum nitride (AlN) contour mode resonators (CMRs). Flicker frequency noise is a fundamental noise mechanism present in any vibrating mechanical structure, whose sources are not generally well understood. 1 GHz AlN CMRs with three different top electrode materials (Al, Au, and Pt) along with various electrode lengths and widths are fabricated to control the overall damping acting on the device. Specifically, the use of different electrode materials allows control of thermoelastic damping (TED), which is the dominant damping mechanism for high frequency AlN CMRs and largely depends on the thermal properties (i.e. thermal diffusivities and expansion coefficients) of the metal electrode rather than the piezoelectric film. We have measured Q and 1/f noise of 68 resonators and the results show that 1/f noise decreases with increasing Q, with a power law dependence that is about 1/Q4. Interestingly, the noise level also depends on the type of electrode materials. Devices with Pt top electrode demonstrate the best noise performance. Our results help unveiling some of the sources of 1/f noise in these resonators, and indicate that a careful selection of the electrode material and dimensions could reduce 1/f noise not only in AlN-CMRs, but also in various classes of resonators, and thus enable ultra-low noise mechanical resonators for sensing and radio frequency applications.

Temporal dynamics of divided spatial attention.

Science.gov (United States)

Itthipuripat, Sirawaj; Garcia, Javier O; Serences, John T

2013-05-01

In naturalistic settings, observers often have to monitor multiple objects dispersed throughout the visual scene. However, the degree to which spatial attention can be divided across spatially noncontiguous objects has long been debated, particularly when those objects are in close proximity. Moreover, the temporal dynamics of divided attention are unclear: is the process of dividing spatial attention gradual and continuous, or does it onset in a discrete manner? To address these issues, we recorded steady-state visual evoked potentials (SSVEPs) as subjects covertly monitored two flickering targets while ignoring an intervening distractor that flickered at a different frequency. All three stimuli were clustered within either the lower left or the lower right quadrant, and our dependent measure was SSVEP power at the target and distractor frequencies measured over time. In two experiments, we observed a temporally discrete increase in power for target- vs. distractor-evoked SSVEPs extending from ∼350 to 150 ms prior to correct (but not incorrect) responses. The divergence in SSVEP power immediately prior to a correct response suggests that spatial attention can be divided across noncontiguous locations, even when the targets are closely spaced within a single quadrant. In addition, the division of spatial attention appears to be relatively discrete, as opposed to slow and continuous. Finally, the predictive relationship between SSVEP power and behavior demonstrates that these neurophysiological measures of divided attention are meaningfully related to cognitive function.

2008 wind farm submission requirements

Energy Technology Data Exchange (ETDEWEB)

NONE

2008-05-01

Wind turbines used to generate electricity can have important visual, environmental and amenity impacts depending on their location. Planning can contribute to the provision of renewable energy by enabling wind energy development in appropriate locations in a manner that appropriately balances their environmental, social and economic benefits with any demonstrated visual, environmental and amenity impacts. The County of Bruce, Ontario and member municipalities are attempting to balance these matters in favour of an overall net community benefit. Planning applications need to include sufficient information and explanation to allow the approval authorities to come to a sound and timely decision, in order to facilitate a viable wind energy industry. This document outlined the County of Bruce application requirements in order to assist in the design and siting of proposed wind energy facilities and in preparing planning applications. The County of Bruce official plan and policies for large wind energy conversion systems (LWECS) were presented. Submissions requirements include an environmental screening report; a federal environmental assessment clearance; a prime agricultural land justification report; a general project description; turbine specifications; noise evaluation; shadow flicker calculations; visual effect modelling; NAV Canada/Transport Canada clearance; grid connections and routing; project staging; overshadowing study; electromagnetic interference study; turbine foundation drawings; and an environmental management plan. Other requirements include lot level maps; project area maps; sensitive receptor table; shadow flicker; stage 2 archaeological study; type certification; statement of planning policy conformity; and a submission checklist. 6 refs., 1 tab., 3 appendices.

Policies and means to assess and improve service quality in public electricity supply systems; Methodes et moyens pour evaluer et ameliorer la qualite du service des reseaux publics de distribution d`electricite

Energy Technology Data Exchange (ETDEWEB)

Lagostena, L.; Mirra, C.; Noferi, P.L.; Sani, G. [ENEL, (Italy)

1992-12-31

Quality in service from electric utilities does not only imply voltage characteristics and points of delivery. Continuity of supply is also an important factor which needs to be assessed in relation to the disturbances and outages. Short interruptions, voltage dips, transient overvoltages, harmonics and flicker are the main occurrences taken into consideration. Measures which may lead to an improvement in the quality of service were identified. The potential advantages of adopting automatic devices and optimizing maintenance work on distribution networks was discussed. 2 refs., 2 tabs., 3 figs.

SSVEP-modulation by covert and overt attention: Novel features for BCI in attention neuro-rehabilitation

DEFF Research Database (Denmark)

Ordikhani-Seyedlar, Mehdi; Sørensen, Helge Bjarup Dissing; Kjaer, Troels W.

2014-01-01

In this pilot study the effect of attention (covert and overt) on the signal detection and classification of steady-state visual-evoked potential (SSVEP) were investigated. Using the SSVEP-based paradigm, data were acquired from 4 subjects using 3 scalp electroencephalography (EEG) electrodes...... located on the visual area. Subjects were instructed to perform the attention task in which they attended covertly or overtly to either of the stimuli flickering with different frequencies (6, 7, 8 and 9Hz). We observed a decrease in signal power in covert compared to the overt attention. However...

Numerical modeling of optical coherent transient processes with complex configurations-III: Noisy laser source

International Nuclear Information System (INIS)

Chang Tiejun; Tian Mingzhen

2007-01-01

A previously developed numerical model based on Maxwell-Bloch equations was modified to simulate optical coherent transient and spectral hole burning processes with noisy laser sources. Random walk phase noise was simulated using laser-phase sequences generated numerically according to the normal distribution of the phase shift. The noise model was tested by comparing the simulated spectral hole burning effect with the analytical solution. The noise effects on a few typical optical coherence transient processes were investigated using this numerical tool. Flicker and random walk frequency noises were considered in accumulation process

Caracterización de una pantalla LCoS con polarimetría de Stokes promedio y aplicación a la simulación de elementos de fase

OpenAIRE

Martínez Guardiola, Francisco Javier; Márquez Ruiz, Andrés; Gallego Rico, Sergi; Ortuño Sánchez, Manuel; Francés Monllor, Jorge; Pascual Villalobos, Inmaculada; Beléndez Vázquez, Augusto

2015-01-01

Recientemente demostramos una técnica de caracterización, la polarimetría de Stokes promedio, que permite obtener tanto el retardo en función del voltaje como la amplitud del flicker que presentan muchas pantallas de cristal líquido sobre silicio de alineación paralela (PA-LCoS). En este trabajo mostramos que conociendo ambas magnitudes podemos simular y diseñar elementos ópticos de fase multinivel para ser enviados a la pantalla PALCoS, con una muy buena capacidad predictiva. Financiado p...

Multicolour LEDs in educational demonstrations of physics and optometry

Science.gov (United States)

Paulins, Paulis; Ozolinsh, Maris

2014-07-01

LED light sources are used to design experimental setup for university courses teaching human color vision. The setup allows to demonstrate various vision characteristics and to apply for student practical exercises to study eye spectral sensitivity in different spectral range using heterochromatic flicker photometry. Technique can be used in laboratory works for students to acquire knowledge in visual perception, basics of electronics and measuring, or it can be applied as fully computer control experiment. Besides studies of the eye spectral sensitivity students can practice in trichromatic color matching and other visual perception tasks

Assessment of filament led bulbs with respect to temporal light artefacts

DEFF Research Database (Denmark)

Lindén, Johannes; Thorseth, Anders; Corell, Dennis Dan

2017-01-01

Temporal light artefacts, abbreviated TLAs (including flicker, stroboscopic effect and phantom arrays), i.e. undesired time modulation in luminance from a light source, has shown to be a threat to wider SSL adoption especially related to dimming functions and low-quality LED products. This is due...... to the effects that both noticeable and unperceivable TLAs have on human perception and wellbeing. In the present work a number of filament LED bulbs, currently available on the market, are assessed primarily with respect to TLAs, but also with respect to photometric, colorimetric and efficiency properties...

Hue shifts produced by temporal asymmetries in chromatic signals depend on the alignment of the first and second harmonics.

Science.gov (United States)

Stockman, Andrew; Henning, G Bruce; West, Peter; Rider, Andrew T; Ripamonti, Caterina

2017-08-01

When M- or L-cone-isolating sawtooth waveforms flicker at frequencies between 4 and 13.3 Hz, there is a mean hue shift in the direction of the shallower sawtooth slope. Here, we investigate how this shift depends on the alignment of the first and second harmonics of sawtooth-like waveforms. Below 4 Hz, observers can follow hue variations caused by both harmonics, and reliably match reddish and greenish excursions. At higher frequencies, however, the hue variations appear as chromatic flicker superimposed on a steady light, the mean hue of which varies with second-harmonic alignment. Observers can match this mean hue against a variable-duty-cycle rectangular waveform and, separately, set the alignment at which the mean hue flips between reddish and greenish. The maximum hue shifts were approximately frequency independent and occurred when the peaks or troughs of the first and second harmonics roughly aligned at the visual input-consistent with the hue shift's being caused by an early instantaneous nonlinearity that saturates larger hue excursions. These predictions, however, ignore phase delays introduced within the chromatic pathway between its input and the nonlinearity that produces the hue shifts. If the nonlinearity follows the substantial filtering implied by the chromatic temporal contrast-sensitivity function, phase delays will alter the alignment of the first and second harmonics such that at the nonlinearity, the waveforms that produce the maximum hue shifts might well be those with the largest differences in rising and falling slopes-consistent with the hue shift's being caused by a central nonlinearity that limits the rate of hue change.

The coupling of cerebral blood flow and oxygen metabolism with brain activation is similar for simple and complex stimuli in human primary visual cortex.

Science.gov (United States)

Griffeth, Valerie E M; Simon, Aaron B; Buxton, Richard B

2015-01-01

Quantitative functional MRI (fMRI) experiments to measure blood flow and oxygen metabolism coupling in the brain typically rely on simple repetitive stimuli. Here we compared such stimuli with a more naturalistic stimulus. Previous work on the primary visual cortex showed that direct attentional modulation evokes a blood flow (CBF) response with a relatively large oxygen metabolism (CMRO2) response in comparison to an unattended stimulus, which evokes a much smaller metabolic response relative to the flow response. We hypothesized that a similar effect would be associated with a more engaging stimulus, and tested this by measuring the primary human visual cortex response to two contrast levels of a radial flickering checkerboard in comparison to the response to free viewing of brief movie clips. We did not find a significant difference in the blood flow-metabolism coupling (n=%ΔCBF/%ΔCMRO2) between the movie stimulus and the flickering checkerboards employing two different analysis methods: a standard analysis using the Davis model and a new analysis using a heuristic model dependent only on measured quantities. This finding suggests that in the primary visual cortex a naturalistic stimulus (in comparison to a simple repetitive stimulus) is either not sufficient to provoke a change in flow-metabolism coupling by attentional modulation as hypothesized, that the experimental design disrupted the cognitive processes underlying the response to a more natural stimulus, or that the technique used is not sensitive enough to detect a small difference. Copyright © 2014 Elsevier Inc. All rights reserved.

Maternal Knowledge and Use of Galactagogues in Andean Communities of Cusco, Peru

Directory of Open Access Journals (Sweden)

Madalena Monteban

2017-09-01

Full Text Available A commonly reported reason for early breastfeeding cessation is inadequate milk production. In response, women across the globe turn to galactagogues – substances used to increase the milk supply. Andean women have traditional knowledge about the medicinal and nutritional properties of plants and animals that are considered good to eat during breastfeeding. This research explores the maintenance and use of galactagogues, and specifically the use of the Andean flicker bird, within the wider framework of breastfeeding and nutrition policies in Peru. To elicit maternal knowledge and use of galactagogues, semi-structured and free-listing interviews were conducted with 33 mothers. Data analysis calculated the frequency and percentage of women reporting each type of galactagogue. In addition, thematic codes and relevant text passages were used in an iterative analytic process to document emerging themes. Identified galactagogues included five plants and six animals. Several galactagogues included protein-rich foods such as lamb meat and the Andean flicker bird. The use of protein-rich galactagogues as solid food is reinforced by public health messages. However, galactagogues in the research communities are usually consumed as soups or drinks, which are less rich in proteins than solid meals. The potential role of liquid galactagogues in the maintenance of appropriate hydration levels during breastfeeding in an environment where safe drinking water is scarce is a new contribution to the existing literature. The results are relevant to the design of maternal and child health policies that comply with intercultural health premises that value and respect the knowledge and practices of Andean Peoples.

Attention is allocated closely ahead of the target during smooth pursuit eye movements: Evidence from EEG frequency tagging.

Science.gov (United States)

Chen, Jing; Valsecchi, Matteo; Gegenfurtner, Karl R

2017-07-28

It is under debate whether attention during smooth pursuit is centered right on the pursuit target or allocated preferentially ahead of it. Attentional deployment was previously probed using a secondary task, which might have altered attention allocation and led to inconsistent findings. We measured frequency-tagged steady-state visual evoked potentials (SSVEP) to measure attention allocation in the absence of any secondary probing task. The observers pursued a moving dot while stimuli flickering at different frequencies were presented at various locations ahead or behind the pursuit target. We observed a significant increase in EEG power at the flicker frequency of the stimulus in front of the pursuit target, compared to the frequency of the stimulus behind. When testing many different locations, we found that the enhancement was detectable up to about 1.5° ahead during pursuit, but vanished by 3.5°. In a control condition using attentional cueing during fixation, we did observe an enhanced EEG response to stimuli at this eccentricity, indicating that the focus of attention during pursuit is narrower than allowed for by the resolution of the attentional system. In a third experiment, we ruled out the possibility that the SSVEP enhancement was a byproduct of the catch-up saccades occurring during pursuit. Overall, we showed that attention is on average allocated ahead of the pursuit target during smooth pursuit. EEG frequency tagging seems to be a powerful technique that allows for the investigation of attention/perception implicitly when an overt task would be confounding. Copyright © 2017 Elsevier Ltd. All rights reserved.

Electrical coupling suppression and transient response improvement for a microgyroscope using ascending frequency drive with a 2-DOF PID controller

International Nuclear Information System (INIS)

Cui, J; Guo, Z Y; Yang, Z C; Hao, Y L; Yan, G Z

2011-01-01

In this paper, we demonstrate a novel control strategy for the drive mode of a microgyroscope using ascending frequency drive (AFD) with an AGC-2DOF PID controller, which drives a resonator with a modulation signal not at the resonant frequency and senses the vibration signal at the resonant frequency, thus realizing the isolation between the actual mechanical response and electrical coupling signal. This approach holds the following three advantages: (1) it employs the AFD signal instead of the resonant frequency drive signal to excite the gyroscope in the drive direction, suppressing the electrical coupling from the drive electrode to the sense electrode; (2) it can reduce the noise at low frequency and resonant frequency by shifting flicker noise to the high-frequency part; (3) it can effectively improve the performance of the transient response of the closed-loop control with a 2-DOF (degree of freedom) PID controller compared with the conventional 1-DOF PID. The stability condition of the whole loop is investigated by utilizing the averaging and linearization method. The control approach is applied to drive a lateral tuning fork microgyroscope. Test results show good agreement with the theoretical and simulation results. The non-ideal electrical antiresonance peak is removed and the resonant peak height increases by approximately 10 dB over a 400 Hz span with a flicker noise reduction of 30 dB within 100 Hz using AFD. The percent overshoot is reduced from 36.2% (1DOF PID) to 8.95% (2DOF PID, about 75.3% overshoot suppression) with 15.3% improvement in setting time

The impact of electrode materials on 1/f noise in piezoelectric AlN contour mode resonators

Directory of Open Access Journals (Sweden)

Hoe Joon Kim

2018-05-01

Full Text Available This paper presents a detailed analysis on the impact of electrode materials and dimensions on flicker frequency (1/f noise in piezoelectric aluminum nitride (AlN contour mode resonators (CMRs. Flicker frequency noise is a fundamental noise mechanism present in any vibrating mechanical structure, whose sources are not generally well understood. 1 GHz AlN CMRs with three different top electrode materials (Al, Au, and Pt along with various electrode lengths and widths are fabricated to control the overall damping acting on the device. Specifically, the use of different electrode materials allows control of thermoelastic damping (TED, which is the dominant damping mechanism for high frequency AlN CMRs and largely depends on the thermal properties (i.e. thermal diffusivities and expansion coefficients of the metal electrode rather than the piezoelectric film. We have measured Q and 1/f noise of 68 resonators and the results show that 1/f noise decreases with increasing Q, with a power law dependence that is about 1/Q4. Interestingly, the noise level also depends on the type of electrode materials. Devices with Pt top electrode demonstrate the best noise performance. Our results help unveiling some of the sources of 1/f noise in these resonators, and indicate that a careful selection of the electrode material and dimensions could reduce 1/f noise not only in AlN-CMRs, but also in various classes of resonators, and thus enable ultra-low noise mechanical resonators for sensing and radio frequency applications.

Impaired Retinal Vasodilator Responses in Prediabetes and Type 2 Diabetes

Science.gov (United States)

Lott, Mary E.J.; Slocomb, Julia E.; Shivkumar, Vikram; Smith, Bruce; Quillen, David; Gabbay, Robert A.; Gardner, Thomas W.; Bettermann, Kerstin

2013-01-01

Purpose In diabetes, endothelial dysfunction and subsequent structural damage to blood vessels can lead to heart attacks, retinopathy and strokes. However, it is unclear whether prediabetic subjects exhibit microvascular dysfunction indicating early stages of arteriosclerosis and vascular risk. The purpose of this study was to examine whether retinal reactivity may be impaired early in the hyperglycemic continuum and may be associated with markers of inflammation. Methods Individuals with prediabetes (n = 22), type 2 diabetes (n = 25) and healthy age and body composition matched controls (n = 19) were studied. We used the Dynamic Vessel Analyzer to assess retinal vasoreactivity (percent change in vessel diameter) during a flickering light stimulation. Fasting highly sensitive c-reactive protein (hs-CRP), a marker of inflammation, was measured in blood plasma. Results Prediabetic and diabetic individuals had attenuated peak vasodilator and relative amplitude changes in retinal vein diameters to the flickering light stimulus compared to healthy controls (peak dilation: prediabetic subjects 3.3 ± 1.8 %, diabetic subjects 3.3 ± 2.1% controls 5.6 ± 2.6%, p = .001; relative amplitude: prediabetic subjects 4.3 ± 2.2%, diabetic subjects 5.0 ± 2.6% and control subjects 7.2 ± 3.2%, p = .003). Similar findings were observed in retinal arteries. Levels of hs-CRP were not associated with either retinal vessel response parameters. Conclusion Retinal reactivity was impaired in prediabetic and type 2 diabetic individuals in parallel with reduced insulin sensitivity but not associated with levels of hs-CRP. Retinal vasoreactivity measurements may be a sensitive tool to assess early vascular risk. PMID:23742315

Feature-selective attention in healthy old age: a selective decline in selective attention?

Science.gov (United States)

Quigley, Cliodhna; Müller, Matthias M

2014-02-12

Deficient selection against irrelevant information has been proposed to underlie age-related cognitive decline. We recently reported evidence for maintained early sensory selection when older and younger adults used spatial selective attention to perform a challenging task. Here we explored age-related differences when spatial selection is not possible and feature-selective attention must be deployed. We additionally compared the integrity of feedforward processing by exploiting the well established phenomenon of suppression of visual cortical responses attributable to interstimulus competition. Electroencephalogram was measured while older and younger human adults responded to brief occurrences of coherent motion in an attended stimulus composed of randomly moving, orientation-defined, flickering bars. Attention was directed to horizontal or vertical bars by a pretrial cue, after which two orthogonally oriented, overlapping stimuli or a single stimulus were presented. Horizontal and vertical bars flickered at different frequencies and thereby elicited separable steady-state visual-evoked potentials, which were used to examine the effect of feature-based selection and the competitive influence of a second stimulus on ongoing visual processing. Age differences were found in feature-selective attentional modulation of visual responses: older adults did not show consistent modulation of magnitude or phase. In contrast, the suppressive effect of a second stimulus was robust and comparable in magnitude across age groups, suggesting that bottom-up processing of the current stimuli is essentially unchanged in healthy old age. Thus, it seems that visual processing per se is unchanged, but top-down attentional control is compromised in older adults when space cannot be used to guide selection.

The effect of predictability on subjective duration.

Directory of Open Access Journals (Sweden)

Vani Pariyadath

2007-11-01

Full Text Available Events can sometimes appear longer or shorter in duration than other events of equal length. For example, in a repeated presentation of auditory or visual stimuli, an unexpected object of equivalent duration appears to last longer. Illusions of duration distortion beg an important question of time representation: when durations dilate or contract, does time in general slow down or speed up during that moment? In other words, what entailments do duration distortions have with respect to other timing judgments? We here show that when a sound or visual flicker is presented in conjunction with an unexpected visual stimulus, neither the pitch of the sound nor the frequency of the flicker is affected by the apparent duration dilation. This demonstrates that subjective time in general is not slowed; instead, duration judgments can be manipulated with no concurrent impact on other temporal judgments. Like spatial vision, time perception appears to be underpinned by a collaboration of separate neural mechanisms that usually work in concert but are separable. We further show that the duration dilation of an unexpected stimulus is not enhanced by increasing its saliency, suggesting that the effect is more closely related to prediction violation than enhanced attention. Finally, duration distortions induced by violations of progressive number sequences implicate the involvement of high-level predictability, suggesting the involvement of areas higher than primary visual cortex. We suggest that duration distortions can be understood in terms of repetition suppression, in which neural responses to repeated stimuli are diminished.

Sustained Splits of Attention within versus across Visual Hemifields Produce Distinct Spatial Gain Profiles.

Science.gov (United States)

Walter, Sabrina; Keitel, Christian; Müller, Matthias M

2016-01-01

Visual attention can be focused concurrently on two stimuli at noncontiguous locations while intermediate stimuli remain ignored. Nevertheless, behavioral performance in multifocal attention tasks falters when attended stimuli fall within one visual hemifield as opposed to when they are distributed across left and right hemifields. This "different-hemifield advantage" has been ascribed to largely independent processing capacities of each cerebral hemisphere in early visual cortices. Here, we investigated how this advantage influences the sustained division of spatial attention. We presented six isoeccentric light-emitting diodes (LEDs) in the lower visual field, each flickering at a different frequency. Participants attended to two LEDs that were spatially separated by an intermediate LED and responded to synchronous events at to-be-attended LEDs. Task-relevant pairs of LEDs were either located in the same hemifield ("within-hemifield" conditions) or separated by the vertical meridian ("across-hemifield" conditions). Flicker-driven brain oscillations, steady-state visual evoked potentials (SSVEPs), indexed the allocation of attention to individual LEDs. Both behavioral performance and SSVEPs indicated enhanced processing of attended LED pairs during "across-hemifield" relative to "within-hemifield" conditions. Moreover, SSVEPs demonstrated effective filtering of intermediate stimuli in "across-hemifield" condition only. Thus, despite identical physical distances between LEDs of attended pairs, the spatial profiles of gain effects differed profoundly between "across-hemifield" and "within-hemifield" conditions. These findings corroborate that early cortical visual processing stages rely on hemisphere-specific processing capacities and highlight their limiting role in the concurrent allocation of visual attention to multiple locations.

New Mydriasis-Free Electroretinogram Recorded with Skin Electrodes in Healthy Subjects

Directory of Open Access Journals (Sweden)

Ken Asakawa

2017-01-01

Full Text Available Purpose. To evaluate the reproducibility and consistency of the new mydriasis-free electroretinogram (ERG with a skin electrode (RETeval device, to determine the normative values of parameters, and to clarify the usefulness of pupil records to colored-light stimulus. Methods. A total of 100 eyes of 50 healthy subjects (mean age, 21.4 years were enrolled. The diagnostic parameters obtained by the RETeval device were examined under the following conditions. The reproducibility was determined with the coefficient of variation (CV. The consistency was examined by intraclass correlation coefficients (ICCs. The mean value and the normal range were analyzed with a 95% confidence interval as the normative values of parameters. The correlation of parameters to pupil records (area ratio, constriction ratio and flicker ERG was also examined in the diabetic retinopathy assessment protocol. Results. From the CV for each of the two measurements, the amplitude has a low reproducibility compared with the implicit time. Generally good consistency was obtained with both ERG parameters (ICCs = 0.48–0.92. Moderate correlations were found for the white-, red-, and blue-light stimulus in the area ratio and the constriction ratio, respectively (r = 0.44–0.62; P = 0.010–<0.0001. No correlation was observed between pupil and flicker parameters (r = 0.06–0.34; P = 0.646–0.051. Conclusions. The RETeval device was suggested as a possible screening device to detect the visual afferent diseases by evaluating in combination with the ERG recording and the colored-light pupil response.

An exploratory study evaluating the effects of macular carotenoid supplementation in various retinal diseases

Directory of Open Access Journals (Sweden)

Crosby-Nwaobi R

2016-05-01

Full Text Available Roxanne Crosby-Nwaobi, Philip Hykin, Tunde Peto, Sobha Sivaprasad NIHR Clinical Research Facility, NIHR Moorfields Biomedical Research Centre, London, UK Purpose: The aim of this study was to assess the impact of daily oral supplementation with Macushield (10 mg/d meso-zeaxanthin, 10 mg/d lutein, and 2 mg/d zeaxanthin on eye health in patients with retinal diseases by assessing the macular pigment (MP profile, the visual function, and the quality of life. Methods: Fifty-one patients with various retinal diseases were supplemented daily and followed up for 6 months. The MP optical density was measured using the customized heterochromatic flicker photometry and dual-wavelength autofluorescence. Visual function was evaluated by assessing the change in best corrected visual acuity, contrast sensitivity, and glare sensitivity in mesopic and photopic conditions. Vision-related and general quality of life changes were determined using the National Eye Insititute- Visual Function Questionnaire-25 (NEI-VFQ-25 and EuroQoL-5 dimension questionnaires. Results: A statistically significant increase in the MP optical density was observed using the dual-wavelength autofluorescence (P=0.04 but not with the customized heterochromatic flicker photometry. Statistically significant (P<0.05 improvements in glare sensitivity in low and medium spatial frequencies were observed at 3 months and 6 months. Ceiling effects confounded other visual function tests and quality of life changes. Conclusion: Supplementation with the three carotenoids enhances certain aspects of visual performance in retinal diseases. Keywords: macular pigment optical density, diabetes, central serous retinopathy, age-related macular degeneration

Radio propagation through the turbulent interstellar plasma

International Nuclear Information System (INIS)

Rickett, B.J.

1990-01-01

The current understanding of interstellar scattering is reviewed, and its impact on radio astronomy is examined. The features of interstellar plasma turbulence are also discussed. It is concluded that methods involving the investigation of the flux variability of pulsars and extragalactic sources and the VLBI visibility curves constitute new techniques for probing the ISM. However, scattering causes a seeing limitation in radio observations. It is now clear that variation due to RISS (refractive interstellar scintillations) is likely to be important for several classes of variable sources, especially low-frequency variables and centimeter-wave flickering. 168 refs

Synchronization of EEG activity in patients with bipolar disorder

Science.gov (United States)

Panischev, O. Yu; Demin, S. A.; Muhametshin, I. G.; Demina, N. Yu

2015-12-01

In paper we apply the method based on the Flicker-Noise Spectroscopy (FNS) to determine the differences in frequency-phase synchronization of the cortical electroencephalographic (EEG) activities in patients with bipolar disorder (BD). We found that for healthy subjects the frequency-phase synchronization of EEGs from long-range electrodes was significantly better for BD patients. In BD patients a high synchronization of EEGs was observed only for short-range electrodes. Thus, the FNS is a simple graphical method for qualitative analysis can be applied to identify the synchronization effects in EEG activity and, probably, may be used for the diagnosis of this syndrome.

Experience with Advanced Static VAR Compensators Operating on Wind Farms and in Laboratory in Denmark

DEFF Research Database (Denmark)

Pedersen, Jørgen Kaas; Pedersen, Knud Ole Helgesen; Rasmussen, Tonny Wederberg

1999-01-01

current with ensuing losses, the strong variationS also will cause varying inductive voltage losses in the supply with flicker as a consequence. With power electronic equipment it is possible to produce the reactive power on location and thus reduce the losses and voltage fluctuations in the grid....... This paper describes a 100 kvar power electronic reactive power compensator. The compensator was tested in a wind farm in Western Denmark. The electrical circuit and the working principle of the compensator are described and some survey data are shown. The paper also describes a 2x4 Mvar reactive power...

Maya Studio Projects Dynamics

CERN Document Server

Palamar, Todd

2009-01-01

The only hands-on book devoted to mastering Maya's dynamics tools for water, wind, and fire. In the world of animation, the ability to create realistic water, wind, and fire effects is key. Autodesk Maya software includes powerful dynamics tools that have been used to design breathtaking effects for movies, games, commercials, and short films. This professional guide teaches you the primary techniques you need to make the most of Maya's toolkit, so you'll soon be creating water that ripples, gusting winds and gentle breezes, and flickering fires the way Hollywood pros do. The one-of-a-kind boo

Surface trapping phenomena in thermionic emission generating l/f noise

International Nuclear Information System (INIS)

Stepanescu, A.

1975-01-01

A general expression of the power spectrum of''flicker noise'', involving stochastic trapping phenomena and calculated on the basis of a two parameter model, is applied in the case of thermoionic emission from cathode surface. The fluctuation of the work function over the cathode surface is interpreted as being due to a trapping process of foreign atoms by the cathode. Taking into account the very physical nature of the trapping mechanism, under self-consistent assumptions, a 1/f power spectrum is obtained in a certain range of frequency. The two parameter model removes some discrepancies involved in the preceding theories. (author)

Synergetics and fractals in tribology

CERN Document Server

Janahmadov, Ahad Kh

2016-01-01

This book examines the theoretical and practical aspects of tribological process using synergy, fractal and multifractal methods, and the fractal and multifractal models of self-similar tribosystems developed on their basis. It provides a comprehensive analysis of their effectiveness, and also considers the method of flicker noise spectroscopy with detailed parameterization of surface roughness friction. All models, problems and solutions are taken and tested on the set of real-life examples of oil-gas industry. The book is intended for researchers, graduate students and engineers specialising in the field of tribology, and also for senior students of technical colleges.

Effect of elimination of nitrogen and/or hypoxia or restricted visual environment on color vision and range of accommodation

Science.gov (United States)

Wolbarsht, M. L.; White, C. W.; Anderson, W. B., Jr.

1973-01-01

The effects upon range of accommodation and color vision of reduced atmospheric pressure, at partial and complete elimination of nitrogen, of hypoxia, and of exposure for varying periods of time to restricted visual environment, have been studied alone or in various combinations. Measurements were made on the electroretinogram, the electrooculogram, and the diameter of the retinal vessels as an indicator of blood flow to the retina at the time of total elimination of nitrogen. An objective method was used to test range of accommodation. In the color vision test the flicker colors of a Benham's top were matched with a colorimeter.

WIND VARIABILITY IN BZ CAMELOPARDALIS

International Nuclear Information System (INIS)

Honeycutt, R. K.; Kafka, S.; Robertson, J. W.

2013-01-01

Sequences of spectra of the nova-like cataclysmic variable (CV) BZ Cam were acquired on nine nights in 2005-2006 in order to study the time development of episodes of wind activity known to occur frequently in this star. We confirm the results of Ringwald and Naylor that the P-Cygni absorption components of the lines mostly evolve from higher expansion velocity to lower velocity as an episode progresses. We also commonly find blueshifted emission components in the Hα line profile, whose velocities and durations strongly suggest that they are also due to the wind. Curiously, Ringwald and Naylor reported common occurrences of redshifted Hα emission components in their BZ Cam spectra. We have attributed these emission components in Hα to occasions when gas concentrations in the bipolar wind (both front side and back side) become manifested as emission lines as they move beyond the disk's outer edge. We also suggest, based on changes in the P-Cygni profiles during an episode, that the progression from larger to smaller expansion velocities is due to the higher velocity portions of a wind concentration moving beyond the edge of the continuum light of the disk first, leaving a net redward shift of the remaining absorption profile. We derive a new orbital ephemeris for BZ Cam, using the radial velocity of the core of the He I λ5876 line, finding P = 0.15353(4). Using this period, the wind episodes in BZ Cam are found to be concentrated near the inferior conjunction of the emission line source. This result helps confirm that the winds in nova-like CVs are often phase dependent, in spite of the puzzling implication that such winds lack axisymmetry. We argue that the radiation-driven wind in BZ Cam receives an initial boost by acting on gas that has been lifted above the disk by the interaction of the accretion stream with the disk, thereby imposing flickering timescales onto the wind events, as well as leading to an orbital modulation of the wind due to the non

Critical flicker frequency and continuous reaction times for the diagnosis of minimal hepatic encephalopathy

DEFF Research Database (Denmark)

Lauridsen, Mette Enok Munk; Jepsen, Peter; Vilstrup, Hendrik

2011-01-01

Abstract Minimal hepatic encephalopathy (MHE) is intermittently present in up to 2/3 of patients with chronic liver disease. It impairs their daily living and can be treated. However, there is no consensus on diagnostic criteria except that psychometric methods are required. We compared two easy...... appropriately to a sensory stimulus. The choice of test depends on the information needed in the clinical and scientific care and study of the patients....

Lack of interaction between a new antihistamine, mizolastine, and lorazepam on psychomotor performance and memory in healthy volunteers.

Science.gov (United States)

Patat, A; Perault, M C; Vandel, B; Ulliac, N; Zieleniuk, I; Rosenzweig, P

1995-01-01

1. The possible interaction between a new H1 antihistamine, mizolastine, and lorazepam was assessed in a randomised, double-blind, cross-over, placebo-controlled study involving 16 healthy young male volunteers who received mizolastine 10 mg or placebo once daily for 8 days with a 1 week wash-out interval. The interaction of mizolastine, at steady-state, with a single oral dose of lorazepam or placebo was assessed on days 6 or 8 of each treatment period. 2. Psychomotor performance and cognitive function were evaluated using objective tests (critical flicker fusion threshold, choice reaction time, tapping, arithmetic calculation, body sway) and self-ratings (visual analogue scale, ARCI) before and at 2, 4, 6 and 8 h after dosing. Short-term memory (Sternberg memory scanning immediate free recall of a word list) and long-term memory (delayed free recall and recognition of words and pictures) were assessed before and at 3 h after dosing. Pharmacodynamic interactions were evaluated by repeated measures ANOVA in a 2 x 2 factorial interaction model. 3. Mizolastine, 10 mg once daily, at steady-state, was devoid of sedation and detrimental effect on skilled performance and memory. 4. In contrast, a single 2 mg dose of lorazepam produced marked impairment of psychomotor performance, cognitive functions (significant reduction in flicker fusion threshold, tapping and arithmetic calculation and increase in reaction times and body sway) and subjective sedation from 2 to 8 h after dosing. In addition, lorazepam induced an anterograde amnesia, characterised by a decrease in delayed free recall and recognition, and a deficit in short term memory.(ABSTRACT TRUNCATED AT 250 WORDS)

High blood pressure and visual sensitivity

Science.gov (United States)

Eisner, Alvin; Samples, John R.

2003-09-01

The study had two main purposes: (1) to determine whether the foveal visual sensitivities of people treated for high blood pressure (vascular hypertension) differ from the sensitivities of people who have not been diagnosed with high blood pressure and (2) to understand how visual adaptation is related to standard measures of systemic cardiovascular function. Two groups of middle-aged subjects-hypertensive and normotensive-were examined with a series of test/background stimulus combinations. All subjects met rigorous inclusion criteria for excellent ocular health. Although the visual sensitivities of the two subject groups overlapped extensively, the age-related rate of sensitivity loss was, for some measures, greater for the hypertensive subjects, possibly because of adaptation differences between the two groups. Overall, the degree of steady-state sensitivity loss resulting from an increase of background illuminance (for 580-nm backgrounds) was slightly less for the hypertensive subjects. Among normotensive subjects, the ability of a bright (3.8-log-td), long-wavelength (640-nm) adapting background to selectively suppress the flicker response of long-wavelength-sensitive (LWS) cones was related inversely to the ratio of mean arterial blood pressure to heart rate. The degree of selective suppression was also related to heart rate alone, and there was evidence that short-term changes of cardiovascular response were important. The results suggest that (1) vascular hypertension, or possibly its treatment, subtly affects visual function even in the absence of eye disease and (2) changes in blood flow affect retinal light-adaptation processes involved in the selective suppression of the flicker response from LWS cones caused by bright, long-wavelength backgrounds.

Individual differences in attention strategies during detection, fine discrimination, and coarse discrimination

Science.gov (United States)

Hecker, Elizabeth A.; Serences, John T.; Srinivasan, Ramesh

2013-01-01

Interacting with the environment requires the ability to flexibly direct attention to relevant features. We examined the degree to which individuals attend to visual features within and across Detection, Fine Discrimination, and Coarse Discrimination tasks. Electroencephalographic (EEG) responses were measured to an unattended peripheral flickering (4 or 6 Hz) grating while individuals (n = 33) attended to orientations that were offset by 0°, 10°, 20°, 30°, 40°, and 90° from the orientation of the unattended flicker. These unattended responses may be sensitive to attentional gain at the attended spatial location, since attention to features enhances early visual responses throughout the visual field. We found no significant differences in tuning curves across the three tasks in part due to individual differences in strategies. We sought to characterize individual attention strategies using hierarchical Bayesian modeling, which grouped individuals into families of curves that reflect attention to the physical target orientation (“on-channel”) or away from the target orientation (“off-channel”) or a uniform distribution of attention. The different curves were related to behavioral performance; individuals with “on-channel” curves had lower thresholds than individuals with uniform curves. Individuals with “off-channel” curves during Fine Discrimination additionally had lower thresholds than those assigned to uniform curves, highlighting the perceptual benefits of attending away from the physical target orientation during fine discriminations. Finally, we showed that a subset of individuals with optimal curves (“on-channel”) during Detection also demonstrated optimal curves (“off-channel”) during Fine Discrimination, indicating that a subset of individuals can modulate tuning optimally for detection and discrimination. PMID:23678013

Strong memory in time series of human magnetoencephalograms can identify photosensitive epilepsy

International Nuclear Information System (INIS)

Yulmetyev, R. M.; Yulmetyeva, D. G.; Haenggi, P.; Shimojo, S.; Bhattacharya, J.

2007-01-01

To discuss the salient role of statistical memory effects in human brain functioning, we have analyzed a set of stochastic memory quantifiers that reflects the dynamical characteristics of neuromagnetic responses of magnetoencephalographic signals to a flickering stimulus of different color combinations from a group of control subjects, and compared them with those for a patient with photosensitive epilepsy. We have discovered that the emergence of strong memory and the accompanying transition to a regular and robust regime of chaotic behavior of signals in separate areas for a patient most likely identifies the regions where the protective mechanism against the occurrence of photosensitive epilepsy is located

Synchronization of EEG activity in patients with bipolar disorder

International Nuclear Information System (INIS)

Panischev, O Yu; Demin, S A; Muhametshin, I G; Yu Demina, N

2015-01-01

In paper we apply the method based on the Flicker-Noise Spectroscopy (FNS) to determine the differences in frequency-phase synchronization of the cortical electroencephalographic (EEG) activities in patients with bipolar disorder (BD). We found that for healthy subjects the frequency-phase synchronization of EEGs from long-range electrodes was significantly better for BD patients. In BD patients a high synchronization of EEGs was observed only for short-range electrodes. Thus, the FNS is a simple graphical method for qualitative analysis can be applied to identify the synchronization effects in EEG activity and, probably, may be used for the diagnosis of this syndrome. (paper)

Electrochemical noise from corroding carbon steel and aluminium

International Nuclear Information System (INIS)

Singh, P.R.; Gaonkar, K.B.; De, P.K.; Banerjee, S.

1997-05-01

Electrochemical noise measurements were conducted on carbon steel and aluminium in sodium chloride solutions. Noise parameters like standard deviation of potential and current, noise resistance, pitting index, noise power were studied for the purpose of measuring corrosion rate. These parameters compared well with the corrosion rate. Pitting index was not very reliable. Current noise was more close to the corrosion rates. General corrosion gave rise to white noise type of power spectrum while flicker noise type of spectrum was obtained from pitting attack. Sodium nitrite is shown to inhibit the corrosion of carbon steel. Aluminium corrodes in the early period of exposure and passivates during long exposure

Research on the Method of Noise Error Estimation of Atomic Clocks

Science.gov (United States)

Song, H. J.; Dong, S. W.; Li, W.; Zhang, J. H.; Jing, Y. J.

2017-05-01

The simulation methods of different noises of atomic clocks are given. The frequency flicker noise of atomic clock is studied by using the Markov process theory. The method for estimating the maximum interval error of the frequency white noise is studied by using the Wiener process theory. Based on the operation of 9 cesium atomic clocks in the time frequency reference laboratory of NTSC (National Time Service Center), the noise coefficients of the power-law spectrum model are estimated, and the simulations are carried out according to the noise models. Finally, the maximum interval error estimates of the frequency white noises generated by the 9 cesium atomic clocks have been acquired.

Emotional cues enhance the attentional effects on spatial and temporal resolution.

Science.gov (United States)

Bocanegra, Bruno R; Zeelenberg, René

2011-12-01

In the present study, we demonstrated that the emotional significance of a spatial cue enhances the effect of covert attention on spatial and temporal resolution (i.e., our ability to discriminate small spatial details and fast temporal flicker). Our results indicated that fearful face cues, as compared with neutral face cues, enhanced the attentional benefits in spatial resolution but also enhanced the attentional deficits in temporal resolution. Furthermore, we observed that the overall magnitudes of individuals' attentional effects correlated strongly with the magnitude of the emotion × attention interaction effect. Combined, these findings provide strong support for the idea that emotion enhances the strength of a cue's attentional response.

Strangeness, Magic, Writing

Directory of Open Access Journals (Sweden)

Anne Brewster

2013-09-01

Full Text Available the house with the light burns all night. it seems to be empty: she never hears or sees anyone coming in or out of the door. she never sees anyone through the window—not even a flicker of movement. but every night the light is on and it stays on. the curtain is drawn so she has no idea of the occupants. but one day she notices that the blinds are up and the window open. she is looking onto a large bed with bright red cushions. that is the first and last she sees of the room. she hears months later that the husband had died.

Cycles, scaling and crossover phenomenon in length of the day (LOD) time series

Science.gov (United States)

Telesca, Luciano

2007-06-01

The dynamics of the temporal fluctuations of the length of the day (LOD) time series from January 1, 1962 to November 2, 2006 were investigated. The power spectrum of the whole time series has revealed annual, semi-annual, decadal and daily oscillatory behaviors, correlated with oceanic-atmospheric processes and interactions. The scaling behavior was analyzed by using the detrended fluctuation analysis (DFA), which has revealed two different scaling regimes, separated by a crossover timescale at approximately 23 days. Flicker-noise process can describe the dynamics of the LOD time regime involving intermediate and long timescales, while Brownian dynamics characterizes the LOD time series for small timescales.

Modification by diazepam or thioridazine of the psychomotor skills related to driving: a subacute trial in neurotic out-patients.

Science.gov (United States)

Saario, I; Linnoila, M; Mattila, M J

1976-01-01

Forty-five out-patients with clinically manifested anxiety were tested in order to study the effects of 2 weeks' treatment with placebo, diazepam (5-10 mg three times daily) or thioridazine (25-50 mg three times daily) on their psychomotor skills related to driving. When compared with placebo, diazepam increased the number of mistakes in reaction and co-ordination tests and also decreased ability to discriminate the fusion of flickering light. When compared to other groups, reactive and co-ordinative skills were more impaired in patients treated with thioridazine which also impaired divided attention. Aubjectively thioridazine was not experienced as effective an anxiolytic as diazepam. PMID:973981

Investigation And Mitigation Techniques Of Power Quality Problems In Nuclear Installations

International Nuclear Information System (INIS)

Ayad, N.; Elsherbiny, E.; Eleissawi, H.; Zaher, M.; AbdelSalam, G.

2013-01-01

The electrical power systems are exposed to different types of power quality disturbances problems. Investigation and monitoring of power quality is necessary to maintain accurate operation of sensitive equipment especially for nuclear installations. The present research discusses investigation and monitoring of power quality problems for the electrical sources of nuclear installations. Field power quality data is collected by power analyzer and analyzed with reference to power quality standards. There were several disturbances exceeded the thresholds, they were voltage harmonics and voltage flicker. Mitigation techniques were suggested to install a passive filter at low voltage side and all sensitive and critical loads should be isolated and fed through uninterruptible power supply (UPS)

Evaluación preliminar de la penetración eólica en el sistema eléctrico de la Isla de la Juventud; Preliminary evaluation of wind energy penetration at Young Island Electric System

Directory of Open Access Journals (Sweden)

Miguel Castro Fernández

2011-05-01

Full Text Available El presente trabajo trata, a partir de un análisis preliminar en un territorio del archipiélago cubano, la Isla de la Juventud, ofrecer una visión sobre el tema de la penetración eólica a partir del análisis de los conceptos mas aceptados de este concepto a nivel internacional, así como trata de llamar la atención de que la aplicación del concepto de penetración eólica no es tan simple y tiene a su alrededor conceptos y formas de operación de la red conformada que van mas allá de la propia potencia eólica insertada.  At many countries there is great areas where wind resource are very grateful but the electrical network is weak. At these areas the network capacity could be a limit to exploitation of wind resource.There are two main problems related with the associated power of wind resurge and the network weak. First, it is related with steady state voltage level: when demand is low the voltage level could increase more than permitted limits if the energy production is high. The second problem is related with flicker voltage: the wind resource is not constant and the disconnection of the wind turbines could cause flicker voltage more than permitted limits.In Cuban electric system the presence of weak network is normally and different problems like hurricanes or work this electric system require to divide on electric subsystems with possible high contribution of wind generation. The preliminary analysis at one zone of Cuban´s archipelago from the point of view of wind penetration is presented in this paper.

Resource quantity and quality determine the inter-specific associations between ecosystem engineers and resource users in a cavity-nest web.

Science.gov (United States)

Robles, Hugo; Martin, Kathy

2013-01-01

While ecosystem engineering is a widespread structural force of ecological communities, the mechanisms underlying the inter-specific associations between ecosystem engineers and resource users are poorly understood. A proper knowledge of these mechanisms is, however, essential to understand how communities are structured. Previous studies suggest that increasing the quantity of resources provided by ecosystem engineers enhances populations of resource users. In a long-term study (1995-2011), we show that the quality of the resources (i.e. tree cavities) provided by ecosystem engineers is also a key feature that explains the inter-specific associations in a tree cavity-nest web. Red-naped sapsuckers (Sphyrapicusnuchalis) provided the most abundant cavities (52% of cavities, 0.49 cavities/ha). These cavities were less likely to be used than other cavity types by mountain bluebirds (Sialiacurrucoides), but provided numerous nest-sites (41% of nesting cavities) to tree swallows (Tachycinetabicolour). Swallows experienced low reproductive outputs in northern flicker (Colaptesauratus) cavities compared to those in sapsucker cavities (1.1 vs. 2.1 fledglings/nest), but the highly abundant flickers (33% of cavities, 0.25 cavities/ha) provided numerous suitable nest-sites for bluebirds (58%). The relative shortage of cavities supplied by hairy woodpeckers (Picoidesvillosus) and fungal/insect decay (high quality nest-sites for both bluebirds and swallows. Because both the quantity and quality of resources supplied by different ecosystem engineers may explain the amount of resources used by each resource user, conservation strategies may require different management actions to be implemented for the key ecosystem engineer of each resource user. We, therefore, urge the incorporation of both resource quantity and quality into models that assess community dynamics to improve conservation actions and our understanding of ecological communities based on ecosystem engineering.

Moderate perinatal thyroid hormone insufficiency alters visual system function in adult rats.

Science.gov (United States)

Boyes, William K; Degn, Laura; George, Barbara Jane; Gilbert, Mary E

2018-04-21

Thyroid hormone (TH) is critical for many aspects of neurodevelopment and can be disrupted by a variety of environmental contaminants. Sensory systems, including audition and vision are vulnerable to TH insufficiencies, but little data are available on visual system development at less than severe levels of TH deprivation. The goal of the current experiments was to explore dose-response relations between graded levels of TH insufficiency during development and the visual function of adult offspring. Pregnant Long Evans rats received 0 or 3 ppm (Experiment 1), or 0, 1, 2, or 3 ppm (Experiment 2) of propylthiouracil (PTU), an inhibitor of thyroid hormone synthesis, in drinking water from gestation day (GD) 6 to postnatal day (PN) 21. Treatment with PTU caused dose-related reductions of serum T4, with recovery on termination of exposure, and euthyroidism by the time of visual function testing. Tests of retinal (electroretinograms; ERGs) and visual cortex (visual evoked potentials; VEPs) function were assessed in adult offspring. Dark-adapted ERG a-waves, reflecting rod photoreceptors, were increased in amplitude by PTU. Light-adapted green flicker ERGs, reflecting M-cone photoreceptors, were reduced by PTU exposure. UV-flicker ERGs, reflecting S-cones, were not altered. Pattern-elicited VEPs were significantly reduced by 2 and 3 ppm PTU across a range of stimulus contrast values. The slope of VEP amplitude-log contrast functions was reduced by PTU, suggesting impaired visual contrast gain. Visual contrast gain primarily reflects function of visual cortex, and is responsible for adjusting sensitivity of perceptual mechanisms in response to changing visual scenes. The results indicate that moderate levels of pre-and post-natal TH insufficiency led to alterations in visual function of adult rats, including both retinal and visual cortex sites of dysfunction. Copyright © 2018. Published by Elsevier B.V.

REGRESIÓN BAYESIANA LINEAL PARA CALIBRAR LOS PARÁMETROS DE UN MODELO DE HORNO DE ARCO

Directory of Open Access Journals (Sweden)

Jesser James Marulanda Durango

2013-01-01

Full Text Available Este documento presenta la calibración de los parámetros de un modelo de horno de arco eléctrico, que tiene en cuenta la naturaleza no lineal y la impedancia variable que exhibe este tipo de carga. A partir de la ecuación diferencial no lineal que describe la característica estática voltaje-corriente del arco eléctrico, se establece una ecuación equivalente lineal que facilita el ajuste de las constantes del modelo, usando mediciones reales de voltaje y de corriente tomadas en la etapa más crítica de la operación del horno. Se muestra el procedimiento de ajuste de los parámetros del modelo usando regresión Bayesiana Lineal. Se presenta a través de gráficas, la relación entre los parámetros del modelo de la etapa determinista y el comportamiento de la varianza de las funciones de densidad de probabilidad Gaussianas a posterior con el número de datos usados para la calibración del modelo. La validación de los resultados obtenidos se realiza simulando el modelo con los parámetros estimados para luego comparar éstos con mediciones reales. Se ha utilizado un medidor de Flicker que cumple con el estándar CEI IEC 61000-4-15 para determinar la Sensación Instantánea de Flicker (IFL de las fluctuaciones presentes en las formas de onda reales y simuladas de las corrientes del arco eléctrico. Adicionalmente, se presenta en una gráfica el contenido armónico real y simulado de las corrientes de fase generadas en el horno.

Flickering gives early warning signals of a critical transition to a eutrophic lake state : Letter

NARCIS (Netherlands)

Wang, R.; Dearing, J.; Langdon, P.G.; Zhang, E.; Yang, X.; Dakos, V.; Scheffer, M.

2012-01-01

There is a recognized need to anticipate tipping points, or critical transitions, in social–ecological systems1, 2. Studies of mathematical3, 4, 5 and experimental6, 7, 8, 9 systems have shown that systems may ‘wobble’ before a critical transition. Such early warning signals10 may be due to the

Teacher burnout : a flickering flame : an empirical study among teachers from a social exchange perspective

NARCIS (Netherlands)

Horn, J.E. van

2002-01-01

In this thesis, burnout has been studied among Dutch teachers using the theoretical frame of equity theory. Burnout is a metaphor that describes a particular syndrome which is typically found in human service professions, such as teaching, and is assumed to be linked to the emotional strain of

Why nature needs 1/f noise

International Nuclear Information System (INIS)

Kuzovlev, Yu E

2015-01-01

While ubiquitous at all levels of organization in nature, including in nanotechnology, low-frequency 1/f noise is not yet understood. A possible reason is the unjustified application of probability theory concepts, primarily that of independence, to random physical phenomena. We show that in the framework of statistical mechanics, no medium can impart a definite diffusivity and mobility to a particle that performs random walk through it, which gives rise to flicker fluctuations in these properties. A universal source of 1/f noise in many-particle systems in this example is a dependence of the time behavior of any particular relaxation or transport process on the details of the initial microstate of the system as a whole. (methodological notes)

Fast shuttling of a particle under weak spring-constant noise of the moving trap

Science.gov (United States)

Lu, Xiao-Jing; Ruschhaupt, A.; Muga, J. G.

2018-05-01

We investigate the excitation of a quantum particle shuttled in a harmonic trap with weak spring-constant colored noise. The Ornstein-Uhlenbeck model for the noise correlation function describes a wide range of possible noises, in particular for short correlation times the white-noise limit examined by Lu et al. [Phys. Rev. A 89, 063414 (2014)], 10.1103/PhysRevA.89.063414 and, by averaging over correlation times, "1 /f flicker noise." We find expressions for the excitation energy in terms of static (independent of trap motion) and dynamical sensitivities, with opposite behavior with respect to shuttling time, and demonstrate that the excitation can be reduced by proper process timing and design of the trap trajectory.

Improvement of Frequency Locking Algorithm for Atomic Frequency Standards

Science.gov (United States)

Park, Young-Ho; Kang, Hoonsoo; Heyong Lee, Soo; Eon Park, Sang; Lee, Jong Koo; Lee, Ho Seong; Kwon, Taeg Yong

2010-09-01

The authors describe a novel method of frequency locking algorithm for atomic frequency standards. The new algorithm for locking the microwave frequency to the Ramsey resonance is compared with the old one that had been employed in the cesium atomic beam frequency standards such as NIST-7 and KRISS-1. Numerical simulations for testing the performance of the algorithm show that the new method has a noise filtering performance superior to the old one by a factor of 1.2 for the flicker signal noise and 1.4 for random-walk signal noise. The new algorithm can readily be used to enhance the frequency stability for a digital servo employing the slow square wave frequency modulation.

Dynamic Skin Patterns in Cephalopods

Directory of Open Access Journals (Sweden)

Martin J. How

2017-06-01

Full Text Available Cephalopods are unrivaled in the natural world in their ability to alter their visual appearance. These mollusks have evolved a complex system of dermal units under neural, hormonal, and muscular control to produce an astonishing variety of body patterns. With parallels to the pixels on a television screen, cephalopod chromatophores can be coordinated to produce dramatic, dynamic, and rhythmic displays, defined collectively here as “dynamic patterns.” This study examines the nature, context, and potential functions of dynamic patterns across diverse cephalopod taxa. Examples are presented for 21 species, including 11 previously unreported in the scientific literature. These range from simple flashing or flickering patterns, to highly complex passing wave patterns involving multiple skin fields.

Dynamic Skin Patterns in Cephalopods

Science.gov (United States)

How, Martin J.; Norman, Mark D.; Finn, Julian; Chung, Wen-Sung; Marshall, N. Justin

2017-01-01

Cephalopods are unrivaled in the natural world in their ability to alter their visual appearance. These mollusks have evolved a complex system of dermal units under neural, hormonal, and muscular control to produce an astonishing variety of body patterns. With parallels to the pixels on a television screen, cephalopod chromatophores can be coordinated to produce dramatic, dynamic, and rhythmic displays, defined collectively here as “dynamic patterns.” This study examines the nature, context, and potential functions of dynamic patterns across diverse cephalopod taxa. Examples are presented for 21 species, including 11 previously unreported in the scientific literature. These range from simple flashing or flickering patterns, to highly complex passing wave patterns involving multiple skin fields. PMID:28674500

H1 antihistamines and driving.

Science.gov (United States)

Popescu, Florin Dan

2008-01-01

Driving performances depend on cognitive, psychomotor and perception functions. The CNS adverse effects of some H1 antihistamines can alter the patient ability to drive. Data from studies using standardized objective cognitive and psychomotor tests (Choice Reaction Time, Critical Flicker Fusion. Digital Symbol Substitution Test), functional brain imaging (Positron Emission Tomography, functional Magnetic Resonance Imaging), neurophysiological studies (Multiple Sleep Latency Test, auditory and visual evoked potentials), experimental simulated driving (driving simulators) and real driving studies (the Highway Driving Test, with the evaluation of the Standard Deviation Lateral Position, and the Car Following Test, with the measurement of the Brake Reaction Time) must be discussed in order to classify a H1 antihistamine as a true non-sedating one.

New Observations of the Old Magnetic Nova GQ Muscae

Directory of Open Access Journals (Sweden)

Narloch W.

2014-03-01

Full Text Available Photometric observations of GQ Mus performed between 1992 and 2011 are reported. We find that the total amplitude of the orbital modulation of its brightness decreased from ~ 0.9 mag in 1992 to ~ 0.2 mag in 2010, becoming comparable to the amplitude of chaotic flickering on a time scale of several minutes. Optical spectra obtained in 2001 and 2012 indicate continuing activity of GQ Mus. The spectra show broad emission lines of He II and H I typical for magnetic cataclysmic variables. The nova was found to be an UV-bright object in 2001 and 2012. We also show that the orbital period of GQ Mus has been constant between 1989 and 2010–2011.

The assessment of visually impaired persons working capacities using electrophysiological and ophthalmic ergonomics methods

Directory of Open Access Journals (Sweden)

M. I. Razumovsky

2014-07-01

Full Text Available Aim was to analyze working capacities of visually impaired persons by means of complex electrophysiological and ophthalmic ergonomics eye examination.Materials and methods. Standard clinical ophthalmologic examination (visual acuity measurement, refractometry, biomicroscopy, ophthalmoscopy as well as electrophysiological (electrooculography, electrical sensitivity of the eye, critical flicker fusion frequency and ophthalmic ergonomics tests (accommodation measurement, professional testing using automated system «Proftest-1» were performed.Results. Complex electrophysiological and ophthalmic ergonomics tests were performed in 20 visually impaired persons. Their results revealed direct correlation between electrophysiological and ophthalmic ergonomics indices.Conclusion. Working capacities of visually impaired persons can be assessed reliably using complex electrophysiological and ophthalmic ergonomics eye examination only.

The assessment of visually impaired persons working capacities using electrophysiological and ophthalmic ergonomics methods

Directory of Open Access Journals (Sweden)

M. I. Razumovsky

2014-01-01

Full Text Available Aim was to analyze working capacities of visually impaired persons by means of complex electrophysiological and ophthalmic ergonomics eye examination.Materials and methods. Standard clinical ophthalmologic examination (visual acuity measurement, refractometry, biomicroscopy, ophthalmoscopy as well as electrophysiological (electrooculography, electrical sensitivity of the eye, critical flicker fusion frequency and ophthalmic ergonomics tests (accommodation measurement, professional testing using automated system «Proftest-1» were performed.Results. Complex electrophysiological and ophthalmic ergonomics tests were performed in 20 visually impaired persons. Their results revealed direct correlation between electrophysiological and ophthalmic ergonomics indices.Conclusion. Working capacities of visually impaired persons can be assessed reliably using complex electrophysiological and ophthalmic ergonomics eye examination only.

Rapid visual grouping and figure-ground processing using temporally structured displays.

Science.gov (United States)

Cheadle, Samuel; Usher, Marius; Müller, Hermann J

2010-08-23

We examine the time course of visual grouping and figure-ground processing. Figure (contour) and ground (random-texture) elements were flickered with different phases (i.e., contour and background are alternated), requiring the observer to group information within a pre-specified time window. It was found this grouping has a high temporal resolution: less than 20ms for smooth contours, and less than 50ms for line conjunctions with sharp angles. Furthermore, the grouping process takes place without an explicit knowledge of the phase of the elements, and it requires a cumulative build-up of information. The results are discussed in relation to the neural mechanism for visual grouping and figure-ground segregation. Copyright 2010 Elsevier Ltd. All rights reserved.

Noninvasive detection of macular pigments in the human eye.

Science.gov (United States)

Gellermann, Werner; Bernstein, Paul S

2004-01-01

There is currently strong interest in developing noninvasive technologies for the detection of macular carotenoid pigments in the human eye. These pigments, consisting of lutein and zeaxanthin, are taken up from the diet and are thought to play an important role in the prevention of age-related macular degeneration, the leading cause of blindness in the elderly in the Western world. It may be possible to prevent or delay the onset of this debilitating disease with suitable dietary intervention strategies. We review the most commonly used detection techniques based on heterochromatic flicker photometry, fundus reflectometry, and autofluorescense techniques and put them in perspective with recently developed more molecule-specific Raman detection methods. (c) 2004 Society of Photo-Optical Instrumentation Engineers.

Type I intermittency related to the spatiotemporal dynamics of double layers and ion-acoustic instabilities in plasma

International Nuclear Information System (INIS)

Chiriac, S.; Dimitriu, D. G.; Sanduloviciu, M.

2007-01-01

Anodic double layer instabilities occur in low-temperature diffusion filament-type discharge plasma by applying a certain positive bias with respect to the plasma potential to an additional electrode. Periodic nonlinear regimes, characterized by proper dynamics of double layers, are sustained if excitation and ionization rates in front of the electrode reach the value for which current limitation effects appear in the static current-voltage characteristic. It was experimentally shown that under specific experimental conditions these ordered spatiotemporal phenomena can evolve into chaotic states by type I intermittency. This transition was verified by the evolution of time series, fast Fourier transform amplitude plots, three-dimensional reconstructed state spaces, power laws, and flickering phenomena spectrum, as well as by the return map and tangent bifurcation

El Tor hemolysin of Vibrio cholerae O1 forms channels in planar lipid bilayer membranes.

Science.gov (United States)

Ikigai, H; Ono, T; Iwata, M; Nakae, T; Shimamura, T

1997-05-15

We investigated the channel formation by El Tor hemolysin (molecular mass, 65 kDa) of Vibrio cholerae O1 biotype El Tor in planar lipid bilayers. The El Tor hemolysin channel exhibited asymmetric and hyperbolic membrane current with increasing membrane potential, meaning that the channel is voltage dependent. The zero-current membrane potential measured in KCI solution showed that permeability ratio PK+/PCl- was 0.16, indicating that the channel is 6-fold more anion selective over cation. The hemolysin channel frequently flickered in the presence of divalent cations, suggesting that the channel spontaneously opens and closes. These data imply that the El Tor hemolysin damages target cells by the formation of transmembrane channels and, consequently, is the cause of osmotic cytolysis.

CROSSPLOT-3/CON-3D, 3-D and Stereoscopic Computer-Aided Design Graphics

International Nuclear Information System (INIS)

Grotch, S.L.

1986-01-01

Description of program or function: CROSSPLOT3 is a general three- dimensional point plotting program which generates scatterplots of a data matrix from any user-specified viewpoint. Images can be rotated for a movie-like effect enhancing stereo perception. A number of features can be invoked by the user including: color, class distinction, flickering, sectioning, projections to grid surfaces, and drawing a plane. Plots may be viewed in real time as they are generated. CON3D generates three-dimensional surfaces plus contours on a lower plane from either data on a rectangular grid or an analytical function z=f(x,y). The user may choose any viewing perspective. Plots may be generated in color with many refinements under user control

Polymorphic New World monkeys with more than three M/L cone types

Science.gov (United States)

Jacobs, Gerald H.; Deegan, Jess F.

2005-10-01

Most New World (platyrrhine) monkeys have M/L cone photopigment polymorphisms that map directly into individual variations in visual sensitivity and color vision. We used electroretinogram flicker photometry to examine M/L cone photopigments in the New World monkey Callicebus moloch (the dusky Titi). Like other New World monkeys, this species has an M/L cone photopigment polymorphism that reflects the presence of X-chromosome opsin gene alleles. However, unlike other platyrrhines in which three M/L photopigments are typical, Callicebus has a total of five M/L cone photopigments. The peak sensitivity values for these pigments extend across the range from 530 to 562 nm. The result is an enhanced array of potential color vision phenotypes in this species.

Condition monitoring of shaft of single-phase induction motor using optical sensor

Science.gov (United States)

Fulzele, Asmita G.; Arajpure, V. G.; Holay, P. P.; Patil, N. M.

2012-05-01

Transmission type of optical technique is developed to sense the condition of rotating shafts from a distance. A parallel laser beam is passed tangential over the surface of rotating shaft of a single phase induction motor and its flickering shadow is received on a photo sensor. Variations in sensor voltage output are observed on a digital storage oscilloscope. It is demonstrated that this signal carries information about shaft defects like miss alignment, play and impacts in bearings along with surface deformities. Mathematical model of signals corresponding to these shaft defects is developed. During the development and testing of the sensor, effects of reflections are investigated, sensing phenomenon is simulated, frequency response of the sensor is obtained and its performance is compared with conventional accelerometer.

Dynamic visual noise affects visual short-term memory for surface color, but not spatial location.

Science.gov (United States)

Dent, Kevin

2010-01-01

In two experiments participants retained a single color or a set of four spatial locations in memory. During a 5 s retention interval participants viewed either flickering dynamic visual noise or a static matrix pattern. In Experiment 1 memory was assessed using a recognition procedure, in which participants indicated if a particular test stimulus matched the memorized stimulus or not. In Experiment 2 participants attempted to either reproduce the locations or they picked the color from a whole range of possibilities. Both experiments revealed effects of dynamic visual noise (DVN) on memory for colors but not for locations. The implications of the results for theories of working memory and the methodological prospects for DVN as an experimental tool are discussed.

An enhanced close-in phase noise LC-VCO using parasitic V-NPN transistors in a CMOS process

International Nuclear Information System (INIS)

Gao Peijun; Min Hao; Oh, N J

2009-01-01

A differential LC voltage controlled oscillator (VCO) employing parasitic vertical-NPN (V-NPN) transistors as a negative g m -cell is presented to improve the close-in phase noise. The V-NPN transistors have lower flicker noise compared to MOS transistors. DC and AC characteristics of the V-NPN transistors are measured to facilitate the VCO design. The proposed VCO is implemented in a 0.18 μm CMOS RF/mixed signal process, and the measurement results show the close-in phase noise is improved by 3.5-9.1 dB from 100 Hz to 10 kHz offset compared to that of a similar CMOS VCO. The proposed VCO consumes only 0.41 mA from a 1.5 V power supply. (semiconductor integrated circuits)

Separate and combined effects of the social drugs on psychomotor performance.

Science.gov (United States)

Kerr, J S; Sherwood, N; Hindmarch, I

1991-01-01

Ten female subjects (five smokers and five non-smokers) performed a choice reaction time task (CRT), a compensatory tracking task (CTT), a short-term memory task (STM) and were tested for their critical flicker fusion threshold (CFF) at set points over 4 h after the administration of each possible combination of nicotine (2 mg gum or placebo), caffeine (250 mg capsule or placebo) and alcohol (30 g or placebo). Memory and motor function were shown to be facilitated by nicotine or caffeine, and the debilitating effects of alcohol were frequently antagonised by either drug. In spite of the differences in their neuropharmacological actions, combinations of nicotine, caffeine and alcohol may be compared through their effects on common information processing mechanisms involved in psychomotor performance.

Mitigation of voltage sag, swell and power factor correction using solid-state transformer b

Directory of Open Access Journals (Sweden)

M.R. Banaei

2014-09-01

Full Text Available This paper presents a novel topology of solid-state transformer (SST. In the design process, the AC/DC, DC/AC and AC/AC converters have been integrated to achieve higher efficiency. To obtain higher efficiency from other SST with DC-link topologies, the AC/DC and DC/AC converters have been integrated in one matrix converter. The proposed SST performs typical functions and has advantages such as power factor correction, voltage sag and swell elimination, voltage flicker reduction and protection capability in fault situations. In addition, it has other benefits such as light weight, low volume and elimination of hazardous liquid dielectrics because it uses medium frequency transformer. The operation and some performances of the proposed SST have been verified by the simulation results.

Power Quality. Implications at the Point of Connection

Energy Technology Data Exchange (ETDEWEB)

Cobben, J.F.G.

2007-06-12

The main developments in the field of power quality and mentioned before were an important trigger in arriving at the research objectives. Condensing all information three main research objectives can be described as: (a) Classification of power quality phenomena to arrive at an analysis tool for grid operators, which makes it possible to handle an enormous amount of data and to give customers and the regulator clearer information about the quality of supply voltage; (b) The influence of dispersed generation due to a large amount of renewable energy sources on power quality, especially on the voltage level and slow voltage variations. Also the possible contribution to the harmonic distortion is analysed; (c) Power quality interaction between 'supply' voltage and 'exchanged' current at the point of common coupling (point of connection or POC to the grid). Especially the relation between current capacity of a POC, the grid impedance and the current at the POC is analysed for harmonics and flicker. In chapter 1 power quality in general is described, the problems are stated and the research topics discussed. Further understanding of the different power quality phenomena, is the topic of chapter 2 and the need to use the indices is described. Also the need to develop methods for compressing power quality data and to make this data fit for use is described. The classification explained in this chapter is an example of practical solution, which has been implemented in a system for substation automation. In chapter 3, the voltage magnitude variation as power quality phenomena is analysed. The influence of dispersed generation in relation to this phenomenon is studied. Also the limits of implementing dispersed generation in existing low voltage grids are calculated. The limited possibilities of voltage level regulation with reactive power in the low voltage grid are described, including the influences on the losses in the grid. Chapter 4 is the chapter

Investigation of LO-leakage cancellation and DC-offset influence on flicker-noise in X-band mixers

DEFF Research Database (Denmark)

Michaelsen, Rasmus; Johansen, Tom; Tamborg, Kjeld

2012-01-01

This paper describes an investigation on the influences in 1/f noise of LO-leakage and DC-offset cancellation for X-band mixers. Conditions for LO-leakage cancellation and zero DC-offset is derived. Measurements on a double balanced diode mixer shows an improvement in noise figure from 14.3dB to ...

Inductively coupled plasma mass spectrometry with a twin quadrupole instrument using laser ablation sample introduction and monodisperse dried microparticulate injection

Energy Technology Data Exchange (ETDEWEB)

Allen, Lloyd A. [Iowa State Univ., Ames, IA (United States)

1996-10-17

The focus of this dissertation is the use of a twin quadrupole inductively coupled plasma mass spectrometer (ICP-MS) for the simultaneous detection of two m/z values. The twin quadrupole ICP-MS is used with laser ablation sample introduction in both the steady state (10 Hz) and single pulse modes. Steady state signals are highly correlated and the majority of flicker noise cancels when the ratio is calculated. Using a copper sample, the isotope ratio ⁶³Cu⁺/⁶⁵Cu⁺ is measured with a relative standard deviation (RSD) of 0.26%. Transient signals for single laser pulses are also obtained. Copper isotope ratio measurements for several laser pulses are measured with an RSD of 0.85%. Laser ablation (LA) is used with steel samples to assess the ability of the twin quadrupole ICP-MS to eliminate flicker noise of minor components of steel samples. Isotopic and internal standard ratios are measured in the first part of this work. The isotope ratio ⁵²Cr⁺/⁵³Cr⁺ (Cr present at 1.31 %) can be measured with an RSD of 0.06 % to 0.1 %. For internal standard elements, RSDs improve from 1.9 % in the Cr⁺ signal to 0.12% for the ratio of ⁵¹V⁺ to ⁵²Cr⁺. In the second part of this work, one mass spectrometer is scanned while the second channel measures an individual m/z value. When the ratio of these two signals is calculated, the peak shapes in the mass spectrum are improved significantly. Pulses of analyte and matrix ions from individual drops are measured simultaneously using the twin quadrupole ICP-MS with monodisperse dried microparticulate injection (MDMI). At modest Pb concentrations (500 ppm), a shoulder on the leading edge of the Li⁺ signal becomes apparent. Space charge effects are consistent with the disturbances seen.

Electroretinogram responses of the normal thoroughbred horse sedated with detomidine hydrochloride.

Science.gov (United States)

Church, Melanie L; Norman, Joanna C

2012-09-01

The main objective was to record electroretinogram (ERG) parameters of normal thoroughbred mares using the HMsERG, a mini-Ganzfeld electroretinographic unit, and a contact lens electrode. The second objective was to determine whether IV detomidine hydrochloride at 0.015 mg/kg is consistently an effective choice for sedation of horses undergoing this ERG protocol. The study population consisted of 30 normal thoroughbred mares. ERG data were harvested using a protocol that included three different light intensities (10, 3000, and 10,000 mcd s/m(2)) and a 30-Hz flicker at 3000 mcd s/m(2). Mean, median, standard deviation, and estimated normal ranges using the 5-95% of the data for a- and b-wave implicit times (IT), amplitudes (AMP), and b/a ratios were reported. Scotopic results at low intensity (10 mcd s/m(2)) had estimated ranges for b-wave IT of 41.8-72.9 ms and AMP of 19.8-173.3 μV. Middle intensity (3000 mcd s/m(2)) a-wave IT was 13.2-14.7 ms with a-wave AMP of 68.4-144 μV; the b-wave IT was 28.7-41.5 ms with b-wave AMP of 105.7-271.5 μV; and the b/a ratio was 0.95-2.71. The high-intensity (10,000 mcd s/m(2)) average recordings showed an a-wave IT of 13-14.9 ms, a-wave AMP of 85.7-186.8 μV; b-wave IT of 26.6-45.4 ms, b-wave AMP of 104.7-250.6 μV; and a b/a wave ratio of 0.7-2.0. The 30-Hz cone flicker showed an IT of 22.8-28.9 ms and AMP of 44.1-117.1 μV. Results of normal thoroughbred ERG responses are reported. The protocol proved to be simple and safe and provided consistent results. © 2012 American College of Veterinary Ophthalmologists.

Photovoltaic restoration of sight with high visual acuity

Science.gov (United States)

Lorach, Henri; Goetz, Georges; Smith, Richard; Lei, Xin; Mandel, Yossi; Kamins, Theodore; Mathieson, Keith; Huie, Philip; Harris, James; Sher, Alexander; Palanker, Daniel

2015-01-01

Patients with retinal degeneration lose sight due to gradual demise of photoreceptors. Electrical stimulation of the surviving retinal neurons provides an alternative route for delivery of visual information. We demonstrate that subretinal arrays with 70 μm photovoltaic pixels provide highly localized stimulation, with electrical and visual receptive fields of comparable sizes in rat retinal ganglion cells. Similarly to normal vision, retinal response to prosthetic stimulation exhibits flicker fusion at high frequencies, adaptation to static images and non-linear spatial summation. In rats with retinal degeneration, these photovoltaic arrays provide spatial resolution of 64 ± 11 μm, corresponding to half of the normal visual acuity in pigmented rats. Ease of implantation of these wireless and modular arrays, combined with their high resolution opens the door to functional restoration of sight. PMID:25915832

Detecting fire in video stream using statistical analysis

Directory of Open Access Journals (Sweden)

Koplík Karel

2017-01-01

Full Text Available The real time fire detection in video stream is one of the most interesting problems in computer vision. In fact, in most cases it would be nice to have fire detection algorithm implemented in usual industrial cameras and/or to have possibility to replace standard industrial cameras with one implementing the fire detection algorithm. In this paper, we present new algorithm for detecting fire in video. The algorithm is based on tracking suspicious regions in time with statistical analysis of their trajectory. False alarms are minimized by combining multiple detection criteria: pixel brightness, trajectories of suspicious regions for evaluating characteristic fire flickering and persistence of alarm state in sequence of frames. The resulting implementation is fast and therefore can run on wide range of affordable hardware.

Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames

International Nuclear Information System (INIS)

Chakrabarty, Rajan K.; Novosselov, Igor V.; Beres, Nicholas D.; Moosmüller, Hans; Sorensen, Christopher M.; Stipe, Christopher B.

2014-01-01

We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (−g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in −g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in −g flames, which reduces the time to gel for nanoparticles by ≈10 6  s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.

Trapping and aerogelation of nanoparticles in negative gravity hydrocarbon flames

Energy Technology Data Exchange (ETDEWEB)

Chakrabarty, Rajan K., E-mail: rajan.chakrabarty@gmail.com [Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis, Missouri 63130 (United States); Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Novosselov, Igor V. [Department of Mechanical Engineering, University of Washington, Seattle, Washington 98195 (United States); Enertechnix Inc., Maple Valley, Washington 98068 (United States); Beres, Nicholas D.; Moosmüller, Hans [Laboratory for Aerosol Science, Spectroscopy, and Optics, Desert Research Institute, Nevada System of Higher Education, Reno, Nevada 89512 (United States); Sorensen, Christopher M. [Condensed Matter Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506 (United States); Stipe, Christopher B. [TSI Incorporated, 500 Cardigan Rd, Shoreview, Minnesota 55126 (United States)

2014-06-16

We report the experimental realization of continuous carbon aerogel production using a flame aerosol reactor by operating it in negative gravity (−g; up-side-down configuration). Buoyancy opposes the fuel and air flow forces in −g, which eliminates convectional outflow of nanoparticles from the flame and traps them in a distinctive non-tipping, flicker-free, cylindrical flame body, where they grow to millimeter-size aerogel particles and gravitationally fall out. Computational fluid dynamics simulations show that a closed-loop recirculation zone is set up in −g flames, which reduces the time to gel for nanoparticles by ≈10{sup 6} s, compared to positive gravity (upward rising) flames. Our results open up new possibilities of one-step gas-phase synthesis of a wide variety of aerogels on an industrial scale.

Effects of nicotine gum on psychomotor performance in smokers and non-smokers.

Science.gov (United States)

Hindmarch, I; Kerr, J S; Sherwood, N

1990-01-01

Two experiments were conducted to investigate the effects of nicotine on human performance. In the first study six smokers, who had been allowed to smoke normally prior to testing, completed a battery of psychometric tests (choice reaction time, memory scanning, tracking and flicker fusion threshold) at set points over 4 h after chewing 0, 2, or 4 mg nicotine polacrilex gum. A second study followed a similar design, but used five non-smoker volunteers who were required to chew only the 0 or 2 mg nicotine gum. Blood nicotine levels following the gum were measured in all subjects. The results indicate that additional nicotine improved both the speed and accuracy of motor activity among the smokers, but did not enhance central cognitive processes. No drug effects were found in the non-smoker study.

The human in multiple, hybrid topologies

DEFF Research Database (Denmark)

Svabo, Connie

hybrid associations with a museum exhibition, fellow visitors and portable, mediating technologies such as exercise pamphlets, mobile phone cameras and animal costumes. Museum visitors couple up with various entities and participate in multiple enactments; they associate and dissociate, and thus......Based on ethnographic fieldwork at a modern Danish museum of natural history, and inspired by the philosophical work of Michel Serres and STS scholars Bruno Latour, John Law, Annemarie Mol and Mike Michael, this paper explores the shifting and morphing of museum visitors as they engage in multiple...... constitute shifting fluid and flickering human hybrid topologies. The ethnography of hybrid, morphing museum visitors is related to literature on the relations between people and places. Multiplicity-oriented and heterogeneous ways of conceptualizing the human subject are considered for their implications...

Indoor visible light communication with smart lighting technology

Science.gov (United States)

Das Barman, Abhirup; Halder, Alak

2017-02-01

An indoor visible-light communication performance is investigated utilizing energy efficient white light by 2D LED arrays. Enabled by recent advances in LED technology, IEEE 802.15.7 standardizes high-data-rate visible light communication and advocates for colour shift keying (CSK) modulation to overcome flicker and to support dimming. Voronoi segmentation is employed for decoding N-CSK constellation which has superior performance compared to other existing decoding methods. The two chief performance degrading effects of inter-symbol interference and LED nonlinearity is jointly mitigated using LMS post equalization at the receiver which improves the symbol error rate performance and increases field of view of the receiver. It is found that LMS post equalization symbol at 250MHz offers 7dB SNR improvement at SER10-6

Stress, Visual and Musculoskeletal Complaints in Open Plan Office Staff

Directory of Open Access Journals (Sweden)

Vangelova K.

2014-06-01

Full Text Available The aim of the study was to identify the main ergonomic and organizational risks contributing to stress, visual and musculoskeletal disorders in open plan office workers. A total of 73 subjects of mean age 28.3 ±4.7 years were studied. Measurements of salivary cortisol and self-ratings for strain, fatigue, stress symptoms, visual and musculoskeletal complaints were performed. The work places were organized well, but the studied staff reported high work load and time pressure. The data showed higher cortisol levels during the workday under time pressure. High incidence of visual and musculoskeletal complaints mainly in the region of the back and the neck were found, associated with flickering and blinks on the screen monitors and overtime. Optimizing workplace organization could help reduce stress and health complaints of office staff.

Processing Decoded Video for LCD-LED Backlight Display

DEFF Research Database (Denmark)

Nadernejad, Ehsan

The quality of digital images and video signal on visual media such as TV screens and LCD displays is affected by two main factors; the display technology and compression standards. Accurate knowledge about the characteristics of display and the video signal can be utilized to develop advanced...... on local LED-LCD backlight. Second, removing the digital video codec artifacts such as blocking and ringing artifacts by post-processing algorithms. A novel algorithm based on image features with optimal balance between visual quality and power consumption was developed. In addition, to remove flickering...... algorithms for signal (image or video) enhancement. One particular application of such algorithms is the case of LCDs with dynamic local backlight. The thesis addressed two main problems; first, designing algorithms that improve the visual quality of perceived image and video and reduce power consumption...

Real-Time Video Stylization Using Object Flows.

Science.gov (United States)

Lu, Cewu; Xiao, Yao; Tang, Chi-Keung

2017-05-05

We present a real-time video stylization system and demonstrate a variety of painterly styles rendered on real video inputs. The key technical contribution lies on the object flow, which is robust to inaccurate optical flow, unknown object transformation and partial occlusion as well. Since object flows relate regions of the same object across frames, shower-door effect can be effectively reduced where painterly strokes and textures are rendered on video objects. The construction of object flows is performed in real time and automatically after applying metric learning. To reduce temporal flickering, we extend the bilateral filtering into motion bilateral filtering. We propose quantitative metrics to measure the temporal coherence on structures and textures of our stylized videos, and perform extensive experiments to compare our stylized results with baseline systems and prior works specializing in watercolor and abstraction.

TOF-SIMA analysis of coating on MCP

International Nuclear Information System (INIS)

Luo Chunping; Liang Handong; Sun Dongxu

2007-01-01

Microchannel plate (MCP) is a sophisticated electronic optical device. It has advantages of high gain, small size, and low using voltage as a detector. The electronic transmission film on the MCP input plane could effectively avoid the positive ion feedback, and protect the photocathode, eliminate flicker noise, and prolong the lifespan of the device. In conclusion, the different films of the input plane can affect the performance of the MCP. Therefore, there is practical value to study surface coating composition of MCP for understanding the relationship between composition and performance and developing high-powered MCP. In the experiment, TOF-SIMS is used to study the surface coating composition of MCP. The results show that there are some main metal elements such as Si, K, Cr, Ni, Rh, Cs and Pb in the surface of the MCP. (authors)

Synchronized Firings in Retinal Ganglion Cells in Response to Natural Stimulation

International Nuclear Information System (INIS)

Zhang Ying-Ying; Xiao Lei; Liu Wen-Zhong; Gong Hai-Qing; Liang Pei-Ji

2011-01-01

The response of synchronously firing groups of population retinal ganglion cells (RGCs) to natural movies (NMs) and pseudo-random white-noise checker-board flickering (CB, as control) are investigated using an information-theoretic algorithm. The main results are: (1) the population RGCs tend to fire in synchrony far more frequently than expected by chance during both NM and CB stimulation; (2) more synchronous groups could be formed and each group contains more neurons under NM than CB stimulation; (3) the individual neurons also participate in more groups and have more distinct partners in NM than CB stimulation. All these results suggest that the synchronized firings in RGCs are more extensive and diverse, which may account for more effective information processing in representing the natural visual environment. (cross-disciplinary physics and related areas of science and technology)

Inaudible functional MRI using a truly mute gradient echo sequence

International Nuclear Information System (INIS)

Marcar, V.L.; Girard, F.; Rinkel, Y.; Schneider, J.F.; Martin, E.

2002-01-01

We performed functional MRI experiments using a mute version of a gradient echo sequence on adult volunteers using either a simple visual stimulus (flicker goggles: 4 subjects) or an auditory stimulus (music: 4 subjects). Because the mute sequence delivers fewer images per unit time than a fast echo planar imaging (EPI) sequence, we explored our data using a parametric ANOVA test and a non-parametric Wilcoxon-Mann-Whitney test in addition to performing a cross-correlation analysis. All three methods were in close agreement regarding the location of the BOLD contrast signal change. We demonstrated that, using appropriate statistical analysis, functional MRI using an MR sequence that is acoustically inaudible to the subject is feasible. Furthermore compared with the ''silent'' event-related procedures involving an EPI protocol, our mGE protocol compares favourably with respect to experiment time and the BOLD signal. (orig.)

Christian thought in Momcilo Nastasijevic's poetry

Directory of Open Access Journals (Sweden)

Kostić-Tmušić Aleksandra S.

2012-01-01

Full Text Available Poetry of Momcilo Nastasijevic gives us undoubted motive to talk about him as a consistent religious poet, a poet of orthodox religious inspiration. He approached towards words as sanctity, he endeavoured to measure each word, reach it, and clean it from accumulated dust of everyday’s blather. His attitude towards poetical locution, his personal law of poetical perfection, represents, brought up to the last consequences, principles of symbolist poetics. He thought of words as magic of sound and rhythm and examines all the effects we can get from it. To him, poetry was identical to crucial and the purest flickering of what he called human soul. The thought of our poet come down to essence of his poetry: who has understood his poems, can be sure that will understand Nastasijevic as a poet.

Evaluating the effectiveness of using electroencephalogram power indices to measure visual fatigue.

Science.gov (United States)

Hsu, Bin-Wei; Wang, Mao-Jiun J

2013-02-01

Electroencephalography (EEG) is widely used in cognitive and behavioral research. This study evaluates the effectiveness of using the EEG power index to measure visual fatigue. Three common visual fatigue measures, critical-flicker fusion (CFF), near-point accommodation (NPA), and subjective eye-fatigue rating, were used for comparison. The study participants were 20 men with a mean age of 20.4 yr. (SD = 1.5). The experimental task was a car-racing video game. Results indicated that the EEG power indices were valid as a visual fatigue measure and the sensitivity of the objective measures (CFF and EEG power index) was higher than the subjective measure. The EEG beta and EEG alpha were effective for measuring visual fatigue in short- and long-duration tasks, respectively. EEG beta/alpha were the most effective power indexes for the visual fatigue measure.

Visual activation in infants and young children studied by functional magnetic resonance imaging

DEFF Research Database (Denmark)

Born, Alfred Peter; Leth, H; Miranda Gimenez-Ricco, Maria Jo

1998-01-01

The purpose of this study was to determine whether visual stimulation in sleeping infants and young children can be examined by functional magnetic resonance imaging. We studied 17 children, aged 3 d to 48 mo, and three healthy adults. Visual stimulation was performed with 8-Hz flickering light...... through the sleeping childs' closed eyelids. Functional magnetic resonance imaging was performed with a gradient echoplanar sequence in a l.5-T magnetic resonance scanner. Six subjects were excluded because of movement artifacts; the youngest infant showed no response. In 10 children, we could demonstrate...... flow during activation. The different response patterns in young children and adults can reflect developmental or behavioral differences. Localization of the activation seemed to be age-dependent. In the older children and the adults, it encompassed the whole length of the calcarine sulcus, whereas...

Correlation between the optical coherence tomography and electroretinogram in retinal vein occlusion macular edema

Directory of Open Access Journals (Sweden)

Ya Xu

2014-11-01

Full Text Available AIM: To evaluate the correlation between retinal thickness and photopic flash electroretinogram(ERGparameters(Cone a-wave, Cone b-wave, and 30Hz flickerin patients with central retinal vein occlusion(CRVOand macular edema. METHODS: A total of 25 patients(25 CRVO eyes and 25 unaffected fellow eyeswith CRVO underwent the examination of optical coherence tomography(OCTand photopic falsh ERG. The amplitude and implicit time of the ERG parameters were extracted from the ERG traces. Retinal thicknesses were measured by OCT in nine macular subfields. Then the correlations between ERG parameters and macular morphological parameters were analyzed. RESULTS: The Cone b-wave and 30Hz flicker implicit time were correlated with macular retinal thickness in seven out of nine subfields, excluding the temporal subfields. CONCLUSION: The retinal thickness of the macular edema may be associated with inner retinal function in CRVO patients.

Control of Grid Interactive PV Inverters for High Penetration in Low Voltage Distribution Networks

DEFF Research Database (Denmark)

Demirok, Erhan

Regarding of high density deployment of PV installations in electricity grids, new technical challenges such as voltage rise, thermal loading of network components, voltage unbalance, harmonic interaction and fault current contributions are being added to tasks list of distribution system operators...... of these inverters may depend on grid connection rules which are forced by DSOs. Minimum requirement expected from PV inverters is to transfer maximum power by taking direct current (DC) form from PV modules and release it into AC grid and also continuously keep the inverters synchronized to the grid even under...... for this problem but PV inverters connected to highly capacitive networks are able to employ extra current and voltage harmonics compensation to avoid triggering network resonances at low order frequencies. The barriers such as harmonics interaction, flicker, fault current contribution and dc current injections...

MEDIA MASSA DAN RUANG PUBLIK (Analisis Perilaku Penggunaan Sosial Media dan Kemampuan Remaja dalam menulis

Directory of Open Access Journals (Sweden)

Juwono Tri Atmodjo

2015-11-01

Full Text Available Mass communication media facilitate new web-based way to send a message and the transformation of a media value to others . It appears once as the number and types of social media with an excess of the ability to express ideas, opinions, funny stories, vent arena, and the troubled space with varying terminology The procedure varies penggunaannyapun penggunaannyapun more varied behavior . The survey was to assess the use of social media by ramaja and writing skills gained from the use of social media . Based on data analysis that ; social media most used by teens are Facebook, Twitter , and Yahoo! Messenger and chat through the use of social media is often done . Respondents are not familiar with the use of blogs, SlideShare , instagram, flicker, Skype, Myspace, Friendfeed, and Fhorum . Average use of social media by teens for 3 hours per day , which is accessed through the most HP to update the status, respondents were able to express the idea/ideas and feelings in writing, listening to other people's posts , teens learn the language, able to use symbols used teen, easy of expression, described feeling depressed and juvenile writing skills by using social media .   media komunikasi massa memfasilitasi cara berbasis web untuk mengirim pesan dan transformasi nilai media untuk orang lain. Tampaknya sekali sebagai jumlah dan jenis media sosial dengan kelebihan kemampuan untuk mengekspresikan ide, pendapat, cerita lucu, arena ventilasi, dan ruang bermasalah dengan berbagai terminologi. Prosedur bervariasi penggunaannyapun penggunaannyapun perilaku yang lebih bervariasi. survei ini adalah untuk menilai penggunaan media sosial oleh ramaja dan menulis keterampilan yang diperoleh dari penggunaan media sosial. Berdasarkan analisis data yang; media sosial paling banyak digunakan oleh remaja Facebook, Twitter, dan Yahoo! Messenger dan chatting melalui penggunaan media sosial sering dilakukan. Responden tidak akrab dengan penggunaan blog, Slide

Non-linear signal response functions and their effects on the statistical and noise cancellation properties of isotope ratio measurements by multi-collector plasma mass spectrometry

International Nuclear Information System (INIS)

Doherty, W.

2013-01-01

A nebulizer-centric response function model of the analytical inductively coupled argon plasma ion source was used to investigate the statistical frequency distributions and noise reduction factors of simultaneously measured flicker noise limited isotope ion signals and their ratios. The response function model was extended by assuming i) a single gaussian distributed random noise source (nebulizer gas pressure fluctuations) and ii) the isotope ion signal response is a parabolic function of the nebulizer gas pressure. Model calculations of ion signal and signal ratio histograms were obtained by applying the statistical method of translation to the non-linear response function model of the plasma. Histograms of Ni, Cu, Pr, Tl and Pb isotope ion signals measured using a multi-collector plasma mass spectrometer were, without exception, negative skew. Histograms of the corresponding isotope ratios of Ni, Cu, Tl and Pb were either positive or negative skew. There was a complete agreement between the measured and model calculated histogram skew properties. The nebulizer-centric response function model was also used to investigate the effect of non-linear response functions on the effectiveness of noise cancellation by signal division. An alternative noise correction procedure suitable for parabolic signal response functions was derived and applied to measurements of isotope ratios of Cu, Ni, Pb and Tl. The largest noise reduction factors were always obtained when the non-linearity of the response functions was taken into account by the isotope ratio calculation. Possible applications of the nebulizer-centric response function model to other types of analytical instrumentation, large amplitude signal noise sources (e.g., lasers, pumped nebulizers) and analytical error in isotope ratio measurements by multi-collector plasma mass spectrometry are discussed. - Highlights: ► Isotope ion signal noise is modelled as a parabolic transform of a gaussian variable. ► Flicker

Lidar-based Research and Innovation at DTU Wind Energy – a Review

DEFF Research Database (Denmark)

Mikkelsen, Torben

2014-01-01

" for huge wind turbines, the hub-height of a recently installed 8 MW Vestas V164 turbine soars 143 meters up above the ground, and its rotor of amazing 164 meters in diameter make the turbine tips flicker 225 meters into the sky. Following the revolution in photonics-based telecommunication at the turn...... "Høvsøre" DTU Wind Energy also routinely calibrate and accredit wind lidar manufactures wind lidars. Meanwhile however, new methodologies for power curve assessment based on ground-based and nacelle based lidars have also emerged. For improving the turbines power curve assessments and for advancing...... their control with feed-forward wind measurements experience has also been gained with wind lidars installed on turbine nacelles and integrated into the turbines rotating spinners. A new mobile research infrastructure WindScanner.dk has also emerged at DTU Wind Energy. Wind and turbulence fields are today...

A Sociolinguistic Analysis of "Greeting" and "Introducing": A Preliminary Study of Texts in English Textbooks Used at Junior High School

Directory of Open Access Journals (Sweden)

Lies Amin Lestari

1997-01-01

Full Text Available Abstract: The introduction of the 1994 Curriculum and its meaningfulness approach (Pendekatan Kebermaknaan encourages textbook writers and publishers to publish textbooks in order to meet the needs of both teachers and students for the learning process. That is why at present textbooks of any subjects, including English, are flooding the market. There are some criteria that need to be considered before choosing a textbook for an English class; among others are the authenticity of the language as it is used by the native speakers and its cultural appropriateness (flicker, 1975. This article attempts to analyze three textbooks which are widely used at junior high schools in Surabaya and its nearby towns from the sociolinguistic point of view. The findings show that there are some words or sentences that are sociolinguistically inappropriate and unacceptable eventhough as a whole the textbooks are good and can be used for teaching.

`Full fusion' is not ineluctable during vesicular exocytosis of neurotransmitters by endocrine cells

Science.gov (United States)

Oleinick, Alexander; Svir, Irina; Amatore, Christian

2017-01-01

Vesicular exocytosis is an essential and ubiquitous process in neurons and endocrine cells by which neurotransmitters are released in synaptic clefts or extracellular fluids. It involves the fusion of a vesicle loaded with chemical messengers with the cell membrane through a nanometric fusion pore. In endocrine cells, unless it closes after some flickering (`Kiss-and-Run' events), this initial pore is supposed to expand exponentially, leading to a full integration of the vesicle membrane into the cell membrane-a stage called `full fusion'. We report here a compact analytical formulation that allows precise measurements of the fusion pore expansion extent and rate to be extracted from individual amperometric spike time courses. These data definitively establish that, during release of catecholamines, fusion pores enlarge at most to approximately one-fifth of the radius of their parent vesicle, hence ruling out the ineluctability of `full fusion'.

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...

Suggested Grid Code Modifications to Ensure Wide-Scale Adoption of Photovoltaic Energy in Distributed Power Generation Systems

DEFF Research Database (Denmark)

Yang, Yongheng; Enjeti, Prasad; Blaabjerg, Frede

2013-01-01

Current grid standards seem to largely require low power (e.g. several kilowatts) single-phase photovoltaic (PV) systems to operate at unity power factor with maximum power point tracking, and disconnect from the grid under grid faults. However, in case of a wide-scale penetration of single......-phase PV systems in the distributed grid, the disconnection under grid faults can contribute to: a) voltage flickers, b) power outages, and c) system instability. In this paper, grid code modifications are explored for wide-scale adoption of PV systems in the distribution grid. More recently, Italy...... and Japan, have undertaken a major review of standards for PV power conversion systems connected to low voltage networks. In view of this, the importance of low voltage ride-through for single-phase PV power systems under grid faults along with reactive power injection is studied in this paper. Three...

Wide-Scale Adoption of Photovoltaic Energy

DEFF Research Database (Denmark)

Yang, Yongheng; Enjeti, Prasad; Blaabjerg, Frede

2015-01-01

Current grid standards largely require that low-power (e.g., several kilowatts) single-phase photovoltaic (PV) systems operate at unity power factor (PF) with maximum power point tracking (MPPT), and disconnect from the grid under grid faults by means of islanding detection. However, in the case...... of wide-scale penetration of single-phase PV systems in the distributed grid, disconnection under grid faults can contribute to 1) voltage flickers, 2) power outages, and 3) system instability. This article explores grid code modifications for a wide-scale adoption of PV systems in the distribution grid....... In addition, based on the fact that Italy and Japan have recently undertaken a major review of standards for PV power conversion systems connected to low-voltage networks, the importance of low voltage ride-through (LVRT) for single-phase PV power systems under grid faults is considered, along with three...

Grid simulator for power quality assessment of micro-grids

DEFF Research Database (Denmark)

Carrasco, Joaquin Eloy Garcia; Vasquez, Juan Carlos; Guerrero, Josep M.

2013-01-01

voltages, low-order harmonics and flicker. The aim of this equipment is to test the performance of a given system under such distorted voltages. A prototype of the simulator, consisting of two inverters connected back-to-back to a 380 V three-phase grid and feeding a micro-grid composed of two......-inverter interfaced distributed generators and a critical load was built and tested. A set of experimental results for linear purely resistive loads, non-linear loads and current-controlled inverters is presented to prove the capabilities of the simulator. Finally, a case study is presented by testing a micro-grid.......In this study, a grid simulator based on a back-to-back inverter topology with resonant controllers is presented. The simulator is able to generate three-phase voltages for a range of amplitudes and frequencies with different types of perturbations, such as voltage sags, steady-state unbalanced...

Visual cortex activation recorded by dynamic emission computed tomography of inhaled xenon 133

DEFF Research Database (Denmark)

Henriksen, L; Paulson, O B; Lassen, N A

1981-01-01

to be well suited for detecting focal ischemia. In the present study its ability to detect focal hyperemia was investigated in 13 normal subjects studied during rest and during visual stimulation. A flickering light "seen' with eyes open and closed, increased blood flow in the visual cortex by 35% and 22......Regional cerebral blood flow (CBF) was studied tomographically with 133Xe administered by inhalation over a 1-min period at a concentration of 10 mCi/l. A fast rotating ("dynamic') single-photon emission computed tomograph with four detector heads was used, an instrument that has been found......% respectively. Looking at different pictures displayed on a screen raised regional CBF by 26%. The most complex task, reading and copying a text, increased blood flow by 45%. Averaging the different tasks resulted in a mean regional CBF increase in the visual cortex of 35%. The result is comparable...

Principles of a simulation model for a variable-speed pitch-regulated wind turbine

Energy Technology Data Exchange (ETDEWEB)

Camblong, H.; Vidal, M.R.; Puiggali, J.R.

2004-07-01

This paper considers the basic principles for establishing a simulation- model of a variable speed, pitch regulated, wind turbine. This model is used to test various control algorithms designed with the aim of maximising energetic yield and robustness and minimising flicker emission and dynamic drive train loads. One of the most complex elements of such a system is the interaction between wind and turbine. First, a detailed and didactic analysis of this interaction is given. This is used to understand some complicated phenomena, and to help design a simpler and more efficient (in terms of processing time) mathematical model. Additional submodels are given for the mechanical coupling, the pitch system and the electrical power system, before the entire model is validated by comparison with filed measurements on a 180 kW turbine. The complete simulation model is flexible, efficient and allows easy evaluation of different control algorithms. (author)

Wind energy power plants (wind farms) review and analysis

Energy Technology Data Exchange (ETDEWEB)

Newbold, K B; McKeary, M [McMaster Univ., Hamilton, ON (Canada). McMaster Inst. of Environment and Health

2010-07-01

Global wind power capacity has increased by an average cumulative rate of over 30 percent over the past 10 years. Although wind energy emits no air pollutants and facilities can often share spaces with other activities, public opposition to wind power development is an ongoing cause of concern. Development at the local level in Ontario has been met with fierce opposition on the basis of health concerns, aesthetic values, potential environmental impacts, and economic risks. This report was prepared for the Town of Wasaga Beach, and examined some of the controversy surrounding wind power developments through a review of evidence found in the scientific literature. The impacts of wind power developments related to noise, shadow flicker, avian mortality, bats, and real estate values were evaluated. The study included details of interviews conducted with individuals from Ontario localities where wind farms were located. 77 refs., 1 tab., 1 fig., 2 appendices.

Estimating the short-circuit impedance

DEFF Research Database (Denmark)

Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

1997-01-01

A method for establishing a complex value of the short-circuit impedance from naturally occurring variations in voltage and current is discussed. It is the symmetrical three phase impedance at the fundamental grid frequency there is looked for. The positive sequence components in voltage...... and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

In situ single-atom array synthesis using dynamic holographic optical tweezers

Science.gov (United States)

Kim, Hyosub; Lee, Woojun; Lee, Han-gyeol; Jo, Hanlae; Song, Yunheung; Ahn, Jaewook

2016-01-01

Establishing a reliable method to form scalable neutral-atom platforms is an essential cornerstone for quantum computation, quantum simulation and quantum many-body physics. Here we demonstrate a real-time transport of single atoms using holographic microtraps controlled by a liquid-crystal spatial light modulator. For this, an analytical design approach to flicker-free microtrap movement is devised and cold rubidium atoms are simultaneously rearranged with 2N motional degrees of freedom, representing unprecedented space controllability. We also accomplish an in situ feedback control for single-atom rearrangements with the high success rate of 99% for up to 10 μm translation. We hope this proof-of-principle demonstration of high-fidelity atom-array preparations will be useful for deterministic loading of N single atoms, especially on arbitrary lattice locations, and also for real-time qubit shuttling in high-dimensional quantum computing architectures. PMID:27796372

Italy's contribution, from a medical standpoint, to the space safety of payload scientists, and perspectives for the future

Science.gov (United States)

Rotondo, G.; Ramacci, G. A.; Meineri, G.; Modugno, G. C.; Monesi, F.

In Italy, the selection of the Italian payload scientists has been performed according to the Spacelab Program of ESA. Twenty-four subjects underwent a screening performed by the Health Service of Italian Air Force. They were requested to pass an exercise test on treadmill and another ten-minute test on centrifuge, subject to the effect of + 3 G z. The authors briefly describe the results of the test. Noteworthy is the determination of Central Flicker Fusion Frequency. This parameter makes it possible to assess the endurance level of the subject, much earlier than other techniques (e.g. EKG). The importance of an accurate preliminary screening is emphasized as well as of successive training periods. Future studies will be undertaken to compare evoked cortical potentials with behaviour parameters of space safety, with a view to setting up a subtle tool of evaluation for both future candidates and payload scientists.

65 nm LP/GP mix low cost platform for multi-media wireless and consumer applications

Science.gov (United States)

Tavel, B.; Duriez, B.; Gwoziecki, R.; Basso, M. T.; Julien, C.; Ortolland, C.; Laplanche, Y.; Fox, R.; Sabouret, E.; Detcheverry, C.; Boeuf, F.; Morin, P.; Barge, D.; Bidaud, M.; Biénacel, J.; Garnier, P.; Cooper, K.; Chapon, J. D.; Trouiller, Y.; Belledent, J.; Broekaart, M.; Gouraud, P.; Denais, M.; Huard, V.; Rochereau, K.; Difrenza, R.; Planes, N.; Marin, M.; Boret, S.; Gloria, D.; Vanbergue, S.; Abramowitz, P.; Vishnubhotla, L.; Reber, D.; Stolk, P.; Woo, M.; Arnaud, F.

2006-04-01

A complete 65 nm CMOS platform, called LP/GP Mix, has been developed employing thick oxide transistor (IO), Low Power (LP) and General Purpose (GP) devices on the same chip. Dedicated to wireless multi-media and consumer applications, this new triple gate oxide platform is low cost (+1mask only) and saves over 35% of dynamic power with the use of the low operating voltage GP. The LP/GP mix shows competitive digital performance with a ring oscillator (FO = 1) speed equal to 7 ps per stage (GP) and 6T-SRAM static power lower than 10 pA/cell (LP). Compatible with mixed-signal design requirements, transistors show high voltage gain, low mismatch factor and low flicker noise. Moreover, to address mobile phone demands, excellent RF performance has been achieved with FT = 160 GHz for LP and 280 GHz for GP nMOS transistors.

The where and how of attention-based rehearsal in spatial working memory.

Science.gov (United States)

Postle, B R; Awh, E; Jonides, J; Smith, E E; D'Esposito, M

2004-07-01

Rehearsal in human spatial working memory is accomplished, in part, via covert shifts of spatial selective attention to memorized locations ("attention-based rehearsal"). We addressed two outstanding questions about attention-based rehearsal: the topography of the attention-based rehearsal effect, and the mechanism by which it operates. Using event-related fMRI and a procedure that randomized the presentation of trials with delay epochs that were either filled with a flickering checkerboard or unfilled, we localized the effect to extrastriate areas 18 and 19, and confirmed its absence in striate cortex. Delay-epoch activity in these extrastriate regions, as well as in superior parietal lobule and intraparietal sulcus, was also lateralized on unfilled trials, suggesting that attention-based rehearsal produces a baseline shift in areas representing the to-be-remembered location in space. No frontal regions (including frontal eye fields) demonstrated lateralized activity consistent with a role in attention-based rehearsal.

LI-FI Has Just Been Tested In The Real World And It Is 100 Times Faster Than WI-FI

Directory of Open Access Journals (Sweden)

Praneethkumar

2015-08-01

Full Text Available Light Fidelity refers to Visible Light Communication systems using light-emitting diodes as a medium to high-speed communication in a similar manner as WI-FI. Now a days where internet has become a major demand people are in a search for WI-FI hotspots. LI-FI is New Life of data communication is a better alternative to WI-FI in wireless communication. This paper proposes a survey on LI-FI Technology and analyzes its performance with respect to existing technology. The concept of LI-FI is data communication on fast flickering of light which is not detected by human eye but it is focused on photo detector which converts the on-off state into binary digital data. It has gained a huge popularity in two years of its invention. Such technology has brought not only greener but safer and cheaper future of communication.

Inaudible functional MRI using a truly mute gradient echo sequence

Energy Technology Data Exchange (ETDEWEB)

Marcar, V.L. [University of Zurich, Department of Psychology, Neuropsychology, Treichlerstrasse 10, 8032 Zurich (Switzerland); Girard, F. [GE Medical Systems SA, 283, rue de la Miniere B.P. 34, 78533 Buc Cedex (France); Rinkel, Y.; Schneider, J.F.; Martin, E. [University Children' s Hospital, Neuroradiology and Magnetic Resonance, Department of Diagnostic Imaging, Steinwiesstrasse 75, 8032 Zurich (Switzerland)

2002-11-01

We performed functional MRI experiments using a mute version of a gradient echo sequence on adult volunteers using either a simple visual stimulus (flicker goggles: 4 subjects) or an auditory stimulus (music: 4 subjects). Because the mute sequence delivers fewer images per unit time than a fast echo planar imaging (EPI) sequence, we explored our data using a parametric ANOVA test and a non-parametric Wilcoxon-Mann-Whitney test in addition to performing a cross-correlation analysis. All three methods were in close agreement regarding the location of the BOLD contrast signal change. We demonstrated that, using appropriate statistical analysis, functional MRI using an MR sequence that is acoustically inaudible to the subject is feasible. Furthermore compared with the ''silent'' event-related procedures involving an EPI protocol, our mGE protocol compares favourably with respect to experiment time and the BOLD signal. (orig.)

Direct Cytoskeleton Forces Cause Membrane Softening in Red Blood Cells

Science.gov (United States)

Rodríguez-García, Ruddi; López-Montero, Iván; Mell, Michael; Egea, Gustavo; Gov, Nir S.; Monroy, Francisco

2015-01-01

Erythrocytes are flexible cells specialized in the systemic transport of oxygen in vertebrates. This physiological function is connected to their outstanding ability to deform in passing through narrow capillaries. In recent years, there has been an influx of experimental evidence of enhanced cell-shape fluctuations related to metabolically driven activity of the erythroid membrane skeleton. However, no direct observation of the active cytoskeleton forces has yet been reported to our knowledge. Here, we show experimental evidence of the presence of temporally correlated forces superposed over the thermal fluctuations of the erythrocyte membrane. These forces are ATP-dependent and drive enhanced flickering motions in human erythrocytes. Theoretical analyses provide support for a direct force exerted on the membrane by the cytoskeleton nodes as pulses of well-defined average duration. In addition, such metabolically regulated active forces cause global membrane softening, a mechanical attribute related to the functional erythroid deformability. PMID:26083919

Modelling voltage sag mitigation using dynamic voltage restorer and analyzing power quality issue

Science.gov (United States)

Ismail, Nor Laili; Hidzir, Hizrin Dayana Mohd; Thanakodi, Suresh; Nazar, Nazatul Shiema Moh; Ibrahim, Pungut; Ali, Che Ku Muhammad Sabri Che Ku

2018-02-01

Power quality problem which are arise due to a fault or a pulsed load can have caused an interruption of critical load. The modern power systems are becoming more sensitive to the quality of the power supplied by the utility company. Voltage sags and swells, flicker, interruptions, harmonic distortion and other distortion to the sinusoidal waveform are the examples of the power quality problems. The most affected due to these problems is industrial customers who use a lot of sensitive equipment. There has suffered a huge loss to these problems. Resulting of broken or damage equipment if voltage sag exceeds the sensitive threshold of the equipment. Thus, device such as Static Synchronous Compensator (STATCOM) and Dynamic Voltage Restorer (DVR) has been created to solve this problem among users. DVR is a custom power device that most effective and efficient. This paper intended to report the DVR operations during voltage sag compensation.

Wind Energy Conversion Systems Technology and Trends

CERN Document Server

2012-01-01

Wind Energy Conversion System covers the technological progress of wind energy conversion systems, along with potential future trends. It includes recently developed wind energy conversion systems such as multi-converter operation of variable-speed wind generators, lightning protection schemes, voltage flicker mitigation and prediction schemes for advanced control of wind generators. Modeling and control strategies of variable speed wind generators are discussed, together with the frequency converter topologies suitable for grid integration. Wind Energy Conversion System also describes offshore farm technologies including multi-terminal topology and space-based wind observation schemes, as well as both AC and DC based wind farm topologies. The stability and reliability of wind farms are discussed, and grid integration issues are examined in the context of the most recent industry guidelines. Wind power smoothing, one of the big challenges for transmission system operators, is a particular focus. Fault ride th...

The Role of Head Movements and Signal Spectrum in an Auditory Front/Back Illusion

Directory of Open Access Journals (Sweden)

W Owen Brimijoin

2012-04-01

Full Text Available We used a dynamic auditory spatial illusion to investigate the role of self-motion and acoustics in shaping our spatial percept of the environment. Using motion capture, we smoothly moved a sound source around listeners as a function of their own head movements. A lowpass filtered sound behind a listener that moved in the direction it would have moved if it had been located in the front was perceived as statically located in front. The contrariwise effect occurred if the sound was in front but moved as if it were behind. The illusion was strongest for sounds lowpass filtered at 500 Hz and weakened as a function of increasing lowpass cutoff frequency. The signals with the most high frequency energy were often associated with an unstable location percept that flickered from front to back as self-motion cues and spectral cues for location came into conflict with one another.

A case of radiation optic neuropathy after resection of a pituitary adenoma

Energy Technology Data Exchange (ETDEWEB)

Yoshii, Masaru; Okisaka, Shigekuni; Yanagawa, Youichi; Takiguchi, Hiroshi [National Defense Medical Coll., Tokorozawa, Saitama (Japan)

1995-06-01

A case of optic neuropathy after postoperative radiation therapy is reported. A 69-year-old woman had a partial resection of a pituitary adenoma in 1990 and was treated with 45 Gy of irradiation to the postoperative pituitary lesion for one month. Seven months later she had sudden right visual field loss. Goldmann perimetry examination revealed remarked visual field defect in her right eye with visual acuity of 1.0. The right relative afferent pupillary defect was positive. The value of critical flicker fusion for her right eye was reduced and the amplitude of steady-state pattern-reversal visually evoked cortical potential was significantly less for the right monocular stimulation than that for the fellow eye stimulation, but Ganzfeld electroretinograms were normal for both eyes. Magnetic resonance imaging using Gadolinium-diethylene triaminepenta-acetic acid revealed enhancement on the right optic nerve, which had not been recognized immediately after the radiation therapy, without any suggestion of right optic nerve compression by the residual pituitary adenoma. (author).

Recent progress in the performances of ultrastable quartz resonators and oscillators

Directory of Open Access Journals (Sweden)

Salzenstein Patrice

2016-01-01

Full Text Available Stressed compensated (SC cut led recently to the best frequency stability ever obtained with a quartz oscillator, 2.5 × 10−14 for the flicker frequency modulation (FFM floor. This result is confirmed in this paper with a 3.2 × 10−14 ± 1.1 × 10−14. The quartz resonator is integrated in a 5 MHz enhanced aging box double oven controlled oscillator. After reminding a bit of history, this paper describes how the first significant development in terms of ultra-stable quartz state-of-the-art oscillators was performed in the last 20 years, how the resonators were chosen, and main information about the development of adequate electronics and how to mechanically and thermally stabilized such an ultra-stable oscillator. We also present how to characterize the expected performances, and hot topics in quartz based oscillators.

[Comparative effects of ginkgo biloba extracts on psychomotor performances and memory in healthy subjects].

Science.gov (United States)

Warot, D; Lacomblez, L; Danjou, P; Weiller, E; Payan, C; Puech, A J

1991-01-01

The effect on psychomotor and mnesic performances of acute oral dose (600 mg) of 2 Ginkgo biloba extracts were evaluated in twelve healthy female in a dummy placebo-controlled double blind study. Tests were performed comprising: objective measures of vigilance [critical flicker frequency (CFF), choice reaction time (CRT)], memory tasks (pictures and Sternberg scanning tests) and self-rating evaluation (visual analogue scales). Tests session took place before and 1 hour post-dosing. No statistically significant changes from placebo were observed on CFF, CRT or subjective rating of drug effects. No differences between treatment were evidenced on Sternberg scanning test and pictures recognition. Comparing to baseline, free recall score, while decreasing under placebo and Ginkgo, remained the same under Tanakan. As the differences between treatment are localized on one test, it appears important to examine the reproductility in healthy subjects. In order to verify the clinical relevance of these results, they need to be replicated in older healthy volunteers with age-associated memory impairment.

Acute comparison of clovoxamine and mianserin, alone and in combination with ethanol, on human psychomotor performance.

Science.gov (United States)

Strömberg, C; Mattila, M J

1987-05-01

Objective and subjective effects on human performance of clovoxamine and mianserin were measured in 12 student volunteers who participated in 12 test sessions and received single doses of clovoxamine 50 mg, 100 mg and 150 mg, mianserin 20 mg, and placebo in a double-blind and cross-over manner. Each test drug was given twice, both in combination with alcohol 0.8 g/kg and with a non-alcoholic drink. The tests included tracking, body balance, flicker fusion, horizontal nystagmus, digit symbol substitution, recall memory, and subjective assessments on visual analogue scales. Mianserin and alcohol impaired objective performance in most tests, and their combination showed at least an additive effect. Alcohol counteracted rather than increased mianserin-induced subjective sedation. Clovoxamine neither differed significantly from placebo nor increased alcohol effects. On the contrary, clovoxamine 150 mg reduced significantly alcohol-induced body sway. No evidence of pharmacokinetic interactions were found between the study drugs and alcohol.

Optic neuritis in a case after gamma knife radiosurgery for relapsed pituitary adenoma

International Nuclear Information System (INIS)

Hosoda, Atsuhide; Mizunoya, Satoshi; Abe, Hideki; Kanai, Hidehito; Ikeda, Kazutoshi; Kidahashi, Hisaharu; Suzuki, Masanobu

2008-01-01

The purpose of this study was to report a case of optic neuritis after gamma knife radiosurgery for pituitary adenoma. A 41-year-old woman presented with impaired vision in both eyes since 5 days before. She had received surgery for pituitary tumor 5 years before. She was treated by gamma knife radiosurgery for relapse of tumor 50 days before. Her corrected visual acuity was 0.5 right and 0.6 left. She had abnormal color sense. Flicker fusion frequency was decreased in both eyes. Both eyes showed enlarged blind spot and relative scotoma in the superior sector. Magnetic resonance imaging (MRI) showed enhanced signal in the optic nerve sheath. These findings led to the diagnosis of optic neuritis. Pulsed corticosteroid therapy was followed by improved vision of 1.2 in either eye. She has been doing well for 18 months until present. This case illustrates that optic neuritis may develop after gamma knife radiosurgery. (author)

Novel concept of a PV power generation system adding the function of shunt active filter

Energy Technology Data Exchange (ETDEWEB)

Park, Y.G.; Park, M.; Yu, I.K. [Changwon National Univ., Changwon City (Korea, Republic of). Dept. of Electrical Engineering

2005-07-01

A new photovoltaics (PV) power generation system that used an active filter (AF) function was proposed. The AF was installed to condition reactive power and harmonic compensation as well as flicker and voltage regulation. A maximum point power tracking (MPPT) control system was used to stabilize the voltage source inverter (VSI) output current. A general dq transformation was used to compensate the negative components and the harmonics component. The output terminal of the PV array was connected to a smoothing capacitor interfacing the PV-AF inverter. A voltage source PWM converter was controlled with feedback loops of the output current of the inverter. Optimal values of the power inverter gains and filter constants were tuned to obtain responses. The PV system was simulated using real weather conditions. Results of the study demonstrated the stability and effectiveness of the proposed system. It was concluded that the PV-AF can also be used to provide harmonic damping throughout power distribution systems. 12 refs., 3 tabs., 9 figs.

Electrophysiolocal findings in Mohr-Tranebjærg syndrome

Directory of Open Access Journals (Sweden)

Regina Halfeld Furtado de Mendonça

2015-04-01

Full Text Available Mohr-Tranebjærg syndrome (MTS is an X-liked recessive rare syndrome also known as deafness-dystonia syndrome. The severity of the symptoms may vary, but they progress usually to severe deafness and dystonia and sometimes they are accompanied by cortical deterioration of vision and mental deterioration. The purpose of this paper is to illustrate a very interesting case of Mohr-Tranebjærg syndrome. A 24-year-old italian man with Mohr-Tranebjærg syndrome underwent full field electroretinography (ERG and visual evoked potentials (VEPs. Fundus examination showed apparently normal retina with pallor of the optic disc. Pattern reversal VEP and flash VEP responses were non-recordable. ERG showed amplitude reduction of the fotopic, scotopic and 30 Hz flicker responses revealing generalized retinal dysfunction with reduction of cone and rod responses. The progressive neurodegeneration in Mohr-Tranebjærg syndrome can be also associated with a retinal degeneration.

A case of radiation optic neuropathy after resection of a pituitary adenoma

International Nuclear Information System (INIS)

Yoshii, Masaru; Okisaka, Shigekuni; Yanagawa, Youichi; Takiguchi, Hiroshi

1995-01-01

A case of optic neuropathy after postoperative radiation therapy is reported. A 69-year-old woman had a partial resection of a pituitary adenoma in 1990 and was treated with 45 Gy of irradiation to the postoperative pituitary lesion for one month. Seven months later she had sudden right visual field loss. Goldmann perimetry examination revealed remarked visual field defect in her right eye with visual acuity of 1.0. The right relative afferent pupillary defect was positive. The value of critical flicker fusion for her right eye was reduced and the amplitude of steady-state pattern-reversal visually evoked cortical potential was significantly less for the right monocular stimulation than that for the fellow eye stimulation, but Ganzfeld electroretinograms were normal for both eyes. Magnetic resonance imaging using Gadolinium-diethylene triaminepenta-acetic acid revealed enhancement on the right optic nerve, which had not been recognized immediately after the radiation therapy, without any suggestion of right optic nerve compression by the residual pituitary adenoma. (author)

New structures of power density spectra for four Kepler active galactic nuclei

Science.gov (United States)

Dobrotka, A.; Antonuccio-Delogu, V.; Bajčičáková, I.

2017-09-01

Many nearby active galactic nuclei display a significant short-term variability. In this work, we reanalyse photometric data of four active galactic nuclei observed by Kepler in order to study the flickering activity, with our main goal to search for multiple components in the power density spectra. We find that all four objects have similar characteristics, with two break frequencies at approximately log( f /Hz) = -5.2 and -4.7. We consider some physical phenomena whose characteristic time-scales are consistent with those observed, in particular mass accretion fluctuations in the inner geometrically thick disc (hot X-ray corona) and unstable relativistic Rayleigh-Taylor modes. The former is supported by detection of the same break frequencies in the Swift X-ray data of ZW229-15. We also discuss rms-flux relations, and we detect a possible typical linear trend at lower flux levels. Our findings support the hypothesis of a multiplicative character of variability, in agreement with the propagating accretion fluctuation model.

Qualifying and quantifying minimal hepatic encephalopathy

DEFF Research Database (Denmark)

Morgan, Marsha Y; Amodio, Piero; Cook, Nicola A

2016-01-01

Minimal hepatic encephalopathy is the term applied to the neuropsychiatric status of patients with cirrhosis who are unimpaired on clinical examination but show alterations in neuropsychological tests exploring psychomotor speed/executive function and/or in neurophysiological variables. There is ......Minimal hepatic encephalopathy is the term applied to the neuropsychiatric status of patients with cirrhosis who are unimpaired on clinical examination but show alterations in neuropsychological tests exploring psychomotor speed/executive function and/or in neurophysiological variables...... analytical techniques may provide better diagnostic information while the advent of portable wireless headsets may facilitate more widespread use. A large number of other diagnostic tools have been validated for the diagnosis of minimal hepatic encephalopathy including Critical Flicker Frequency......, the Inhibitory Control Test, the Stroop test, the Scan package and the Continuous Reaction Time; each has its pros and cons; strengths and weaknesses; protagonists and detractors. Recent AASLD/EASL Practice Guidelines suggest that the diagnosis of minimal hepatic encephalopathy should be based on the PHES test...

Tracking the allocation of attention using human pupillary oscillations

Directory of Open Access Journals (Sweden)

Marnix eNaber

2013-12-01

Full Text Available The muscles that control the pupil are richly innervated by the autonomic nervous system. While there are central pathways that drive pupil dilations in relation to arousal, there is no anatomical evidence that cortical centers involved with visual selective attention innervate the pupil. In this study, we show that such connections must exist. Specifically, we demonstrate a novel Pupil Frequency Tagging (PFT method, where oscillatory changes in stimulus brightness over time are mirrored by pupil constrictions and dilations. We find that the luminance induced pupil oscillations are enhanced when covert attention is directed to the flicker stimulus and when targets are correctly detected in an attentional tracking task. These results suggest that the amplitudes of pupil responses closely follow the allocation of focal visual attention and the encoding of stimuli. PFT provides a new opportunity to study top down visual attention itself as well as identifying the pathways and mechanisms that support this unexpected phenomenon.

Comparison of electrothermal atomization diode laser Zeeman- and wavelength-modulated atomic absorption and coherent forward scattering spectrometry

International Nuclear Information System (INIS)

Blecker, Carlo R.; Hermann, Gerd M.

2009-01-01

Atomic absorption and coherent forward scattering spectrometry by using a near-infrared diode laser with and without Zeeman and wavelength modulation were carried out with graphite furnace electrothermal atomization. Analytical curves and limits of detection were compared. The magnetic field was modulated with 50 Hz, and the wavelength of the diode laser with 10 kHz. Coherent forward scattering was measured with crossed and slightly uncrossed polarizers. The results show that the detection limits of atomic absorption spectrometry are roughly the same as those of coherent forward scattering spectrometry with crossed polarizers. According to the theory with bright flicker noise limited laser sources the detection limits and linear ranges obtained with coherent forward scattering spectrometry with slightly uncrossed polarizers are significantly better than those obtained with crossed polarizers and with atomic absorption spectrometry. This is due to the fact that employing approaches of polarization spectroscopy reduce laser intensity fluctuations to their signal carried fractions

Polarimetric and diffractive evaluation of 3.74 micron pixel-size LCoS in the telecommunications C-band

Science.gov (United States)

Wang, Mi; Martínez, Francisco J.; Márquez, Andrés.; Ye, Yabin; Zong, Liangjia; Pascual, Inmaculada; Beléndez, Augusto

2017-08-01

Liquid-crystal on Silicon (LCoS) microdisplays are one of the competing technologies to implement wavelength selective switches (WSS) for optical telecommunications. Last generation LCoS, with more than 4 megapixels, have decreased pixel size to values smaller than 4 microns, what increases interpixel cross-talk effects such as fringing-field. We proceed with an experimental evaluation of a 3.74 micron pixel size parallel-aligned LCoS (PA-LCoS) device. At 1550 nm, for the first time we use time-average Stokes polarimetry to measure the retardance and its flicker magnitude as a function of voltage. We also verify the effect of the antireflection coating when we try to characterize the PA-LCoS out of the designed interval for the AR coating. Some preliminary results for the performance for binary gratings are also given, where the decrease of modulation range with the increase in spatial frequency is shown, together with some residual polarization effects.

Seeing through the Eyes of Others: Social Interaction Perception in Normal and Schizophrenia Subjects

Directory of Open Access Journals (Sweden)

Zotov M.V.,

2016-01-01

Full Text Available What cognitive processes specify understanding of humans’ behavior in communicative situations? 51 healthy controls and 50 schizophrenia patients were presented with social “silent” video clips and then they performed flicker task and predicted characters’ behavior. During the experiment eye movements were recorded. Observers, who have made successful predictions, evaluated the characters’ actions, specified how they categorized the objects and events, and then profiled the objects’ features, on which just these categorizations were based. Information about these features remained in working memory and directed a communicative situation’s perception. Observers noticed the events, relevant to the viewpoints of the characters, and understood their gazes, gestures and actions. Those, who have made unsuccessful predictions, advanced hypotheses about how the characters categorized the objects and events, but they did not profile the objects’ features, on which categorizations were based. They demonstrated “blindness” to the events, relevant to the viewpoints of the characters, and did not understand a coherence of their actions.

Learning quadratic receptive fields from neural responses to natural stimuli.

Science.gov (United States)

Rajan, Kanaka; Marre, Olivier; Tkačik, Gašper

2013-07-01

Models of neural responses to stimuli with complex spatiotemporal correlation structure often assume that neurons are selective for only a small number of linear projections of a potentially high-dimensional input. In this review, we explore recent modeling approaches where the neural response depends on the quadratic form of the input rather than on its linear projection, that is, the neuron is sensitive to the local covariance structure of the signal preceding the spike. To infer this quadratic dependence in the presence of arbitrary (e.g., naturalistic) stimulus distribution, we review several inference methods, focusing in particular on two information theory-based approaches (maximization of stimulus energy and of noise entropy) and two likelihood-based approaches (Bayesian spike-triggered covariance and extensions of generalized linear models). We analyze the formal relationship between the likelihood-based and information-based approaches to demonstrate how they lead to consistent inference. We demonstrate the practical feasibility of these procedures by using model neurons responding to a flickering variance stimulus.

The Relationship between Lutein and Zeaxanthin Status and Body Fat

Directory of Open Access Journals (Sweden)

Billy R. Hammond

2013-03-01

Full Text Available The objective of this project was to investigate the relationships between total and regional distribution of body fat and tissue lutein (L and zeaxanthin (Z status. Healthy men and women (N = 100; average age: 22.5 year, average BMI: 23.4 kg/m2 were evaluated. Total body and regional fat mass were assessed by dual-energy X-ray absorptiometry (Hologic Delphi A. Serum LZ was measured using reverse phase high-performance liquid chromatography, and retinal LZ (referred to as macular pigment optical density; MPOD was measured using heterochromatic flicker photometry. Body fat percentage (total and regional was inversely related to MPOD (p < 0.01 but no significant relationship was found for serum LZ. Higher body fat percentage, even within relatively healthy limits, is associated with lower tissue LZ status. The results indicate that adiposity may affect the nutritional state of the retina. Such links may be one of the reasons that obesity promotes age-related degenerative conditions of the retina.

Low-frequency 1/f noise in graphene devices

Science.gov (United States)

Balandin, Alexander A.

2013-08-01

Low-frequency noise with a spectral density that depends inversely on frequency has been observed in a wide variety of systems including current fluctuations in resistors, intensity fluctuations in music and signals in human cognition. In electronics, the phenomenon, which is known as 1/f noise, flicker noise or excess noise, hampers the operation of numerous devices and circuits, and can be a significant impediment to the development of practical applications from new materials. Graphene offers unique opportunities for studying 1/f noise because of its two-dimensional structure and widely tunable two-dimensional carrier concentration. The creation of practical graphene-based devices will also depend on our ability to understand and control the low-frequency noise in this material system. Here, the characteristic features of 1/f noise in graphene and few-layer graphene are reviewed, and the implications of such noise for the development of graphene-based electronics including high-frequency devices and sensors are examined.

Presence of strong harmonics during visual entrainment: a magnetoencephalography study.

Science.gov (United States)

Heinrichs-Graham, Elizabeth; Wilson, Tony W

2012-09-01

Visual neurons are known to synchronize their firing with stimuli that flicker at a constant rate (e.g. 12Hz). These so-called visual steady-state responses (VSSR) are a well-studied phenomenon, yet the underlying mechanisms are widely disagreed upon. Furthermore, there is limited evidence that visual neurons may simultaneously synchronize at harmonics of the stimulation frequency. We utilized magnetoencephalography (MEG) to examine synchronization at harmonics of the visual stimulation frequency (18Hz). MEG data were analyzed for event-related-synchronization (ERS) at the fundamental frequency, 36, 54, and 72Hz. We found strong ERS in all bands. Only 31% of participants showed maximum entrainment at the fundamental; others showed stronger entrainment at either 36 or 54Hz. The cortical foci of these responses indicated that the harmonics involved cortices that were partially distinct from the fundamental. These findings suggest that spatially-overlapping subpopulations of neurons are simultaneously entrained at different harmonics of the stimulus frequency. Copyright © 2012 Elsevier B.V. All rights reserved.

Community energy storage and distribution SCADA improvements

International Nuclear Information System (INIS)

Riggins, M.

2010-01-01

The mission of American Electric Power (AEP) is to sustain the real time balance of energy supply and demand. Approximately 2.5 percent of energy generated in the United States (USA) is stored as pumped hydro, compressed air, or in batteries and other devices. This power point presentation discussed the use of SCADA for improving community energy storage (CES) and distribution systems. CES is a distributed fleet of small energy units connected to the transformers in order to serve houses or small commercial loads. CES is operated as a fleet offering multi-megawatt (MW) multi-hour storage. The benefits of CES include backup power, flicker mitigation, and renewable integration. Benefits to the electricity grid include power factor correct, ancillary services, and load leveling at the substation level. SCADA is being used to determine when emergency load reductions are required or when emergency inspections on fans, oil pumps or other devices are needed. An outline of AEP's monitoring system installation plan was also included. tabs., figs.

What you fear will appear: detection of schematic spiders in spider fear.

Science.gov (United States)

Peira, Nathalie; Golkar, Armita; Larsson, Maria; Wiens, Stefan

2010-01-01

Various experimental tasks suggest that fear guides attention. However, because these tasks often lack ecological validity, it is unclear to what extent results from these tasks can be generalized to real-life situations. In change detection tasks, a brief interruption of the visual input (i.e., a blank interval or a scene cut) often results in undetected changes in the scene. This setup resembles real-life viewing behavior and is used here to increase ecological validity of the attentional task without compromising control over the stimuli presented. Spider-fearful and nonfearful women detected schematic spiders and flowers that were added to one of two identical background pictures that alternated with a brief blank in between them (i.e., flicker paradigm). Results showed that spider-fearful women detected spiders (but not flowers) faster than did nonfearful women. Because spiders and flowers had similar low-level features, these findings suggest that fear guides attention on the basis of object features rather than simple low-level features.

Laser line shape and spectral density of frequency noise

International Nuclear Information System (INIS)

Stephan, G.M.; Blin, S.; Besnard, P.; Tam, T.T.; Tetu, M.

2005-01-01

Published experimental results show that single-mode laser light is characterized in the microwave range by a frequency noise which essentially includes a white part and a 1/f (flicker) part. We theoretically show that the spectral density (the line shape) which is compatible with these results is a Voigt profile whose Lorentzian part or homogeneous component is linked to the white noise and the Gaussian part to the 1/f noise. We measure semiconductor laser line profiles and verify that they can be fit with Voigt functions. It is also verified that the width of the Lorentzian part varies like 1/P where P is the laser power while the width of the Gaussian part is more of a constant. Finally, we theoretically show from first principles that laser line shapes are also described by Voigt functions where the Lorentzian part is the laser Airy function and the Gaussian part originates from population noise

LI-FI TECHNOLOGY AND THE NEW CONCEPT OF DATA TRANSFER SECURITY

Directory of Open Access Journals (Sweden)

Ramona DUMITRAȘCU

2017-05-01

Full Text Available Li-Fi is a wireless technology that transmits high-speed data using visible light communication (VLC, it can achieve speeds of 224 gigabits per second in the lab. The potential Li-Fi technology can change a lot in virtual word considering it can provide transmission at 1 GB per second - that's 100 times faster than current average Wi-Fi speeds. By flickering the light from a single LED, Li-Fi technology can transmit far more data than a cellular tower, using Visible Light Communication (VLC technology - a medium that uses visible light between 400 and 800 terahertz (THz. It works basically like an incredibly advanced form of Morse code - flicking an LED on and off at extreme speeds and can be used to write and transmit things in binary code. The benefit of Li-Fi over Wi-Fi, other than potentially much faster speeds, is that because light cannot pass through walls, it makes it a whole lot more secure.

Harmonics added to a flickering light can upset the balance between ON and OFF pathways to produce illusory colors.

Science.gov (United States)

Rider, Andrew T; Henning, G Bruce; Eskew, Rhea T; Stockman, Andrew

2018-04-24

The neural signals generated by the light-sensitive photoreceptors in the human eye are substantially processed and recoded in the retina before being transmitted to the brain via the optic nerve. A key aspect of this recoding is the splitting of the signals within the two major cone-driven visual pathways into distinct ON and OFF branches that transmit information about increases and decreases in the neural signal around its mean level. While this separation is clearly important physiologically, its effect on perception is unclear. We have developed a model of the ON and OFF pathways in early color processing. Using this model as a guide, we can produce imbalances in the ON and OFF pathways by changing the shapes of time-varying stimulus waveforms and thus make reliable and predictable alterations to the perceived average color of the stimulus-although the physical mean of the waveforms does not change. The key components in the model are the early half-wave rectifying synapses that split retinal photoreceptor outputs into the ON and OFF pathways and later sigmoidal nonlinearities in each pathway. The ability to systematically vary the waveforms to change a perceptual quality by changing the balance of signals between the ON and OFF visual pathways provides a powerful psychophysical tool for disentangling and investigating the neural workings of human vision. Copyright © 2018 the Author(s). Published by PNAS.

Visual Symptoms in Adults with Autism Spectrum Disorders

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DR Simmons

2012-07-01

Full Text Available Autism Spectrum Disorders (ASDs are common developmental disorders thought to affect more than 1% of the UK population (Baird et al, 2006, The Lancet 368, 210. Whilst the current official diagnostic criteria for ASD concentrate on signs and symptoms associated with social behaviour, it is also well known that sensory difficulties are a major factor in the presentation of this condition (Simmons et al, 2009, Vision Research 49, 2705. Over the past few years we have been investigating these sensory symptoms of ASD using a combination of questionnaire and focus group data, with the aim of clarifying precisely what they are. Concentrating on the visual symptoms, our questionnaire data revealed that individuals with higher levels of autistic traits complained of more visual symptoms than those with lower trait levels. Specific issues highlighted included problems with bright light, especially artificial lighting and, more specifically, flicker from fluorescent lighting (a particular problem in supermarkets. Some individuals also complained of specific colours in artificial lights. Note that the symptoms associated with these aversions could be particularly strong and involve headache and nausea. The focus group (n = 6 of adults with ASD revealed more detail about these issues. It became clear that low-frequency visual flicker, once noticed, can be hard to divert attention from. Also, seeing certain colours (eg, red would “hurt”. Another symptom reported by a number of individuals is distress caused by strongly repetitive patterns like shelving or grids. General sensory issues highlighted by the focus group included the importance of having control over sensory stimulation in order to reduce sensory stress and how certain types of sensory stimulation could be calming in some situations (although none of our sample reported visual calming experiences other than seeking out natural lighting. Our data provide a fascinating insight into the complex

The role of luminance and chromatic cues in emmetropisation.

Science.gov (United States)

Rucker, Frances J

2013-05-01

flicker the eye grows almost twice as much, and becomes more myopic, compared to when the eye is exposed to luminance flicker. Neural responses of the luminance and colour mechanisms direct accommodation and emmetropisation mechanisms to different focal planes. Therefore, it is likely that the set point of refraction and accommodation is dependent on the sensitivity of the eye to changes in spatial and temporal, colour and luminance contrast. Ophthalmic & Physiological Optics © 2013 The College of Optometrists.

Symbiotic Stars in X-rays

Science.gov (United States)

Luna, G. J. M.; Sokoloski, J. L.; Mukai, K.; Nelson, T.

2014-01-01

Until recently, symbiotic binary systems in which a white dwarf accretes from a red giant were thought to be mainly a soft X-ray population. Here we describe the detection with the X-ray Telescope (XRT) on the Swift satellite of 9 white dwarf symbiotics that were not previously known to be X-ray sources and one that was previously detected as a supersoft X-ray source. The 9 new X-ray detections were the result of a survey of 41 symbiotic stars, and they increase the number of symbiotic stars known to be X-ray sources by approximately 30%. Swift/XRT detected all of the new X-ray sources at energies greater than 2 keV. Their X-ray spectra are consistent with thermal emission and fall naturally into three distinct groups. The first group contains those sources with a single, highly absorbed hard component, which we identify as probably coming from an accretion-disk boundary layer. The second group is composed of those sources with a single, soft X-ray spectral component, which likely arises in a region where low-velocity shocks produce X-ray emission, i.e. a colliding-wind region. The third group consists of those sources with both hard and soft X-ray spectral components. We also find that unlike in the optical, where rapid, stochastic brightness variations from the accretion disk typically are not seen, detectable UV flickering is a common property of symbiotic stars. Supporting our physical interpretation of the two X-ray spectral components, simultaneous Swift UV photometry shows that symbiotic stars with harder X-ray emission tend to have stronger UV flickering, which is usually associated with accretion through a disk. To place these new observations in the context of previous work on X-ray emission from symbiotic stars, we modified and extended the alpha/beta/gamma classification scheme for symbiotic-star X-ray spectra that was introduced by Muerset et al. based upon observations with the ROSAT satellite, to include a new sigma classification for sources with

Power quality assessment

International Nuclear Information System (INIS)

Fathi, H.M.E.

2012-01-01

The electrical power systems are exposed to different types of power quality disturbances problems. Assessment of power quality is necessary for maintaining accurate operation of sensitive equipment's especially for nuclear installations, it also ensures that unnecessary energy losses in a power system are kept at a minimum which lead to more profits. With advanced in technology growing of industrial / commercial facilities in many region. Power quality problems have been a major concern among engineers; particularly in an industrial environment, where there are many large-scale type of equipment. Thus, it would be useful to investigate and mitigate the power quality problems. Assessment of Power quality requires the identification of any anomalous behavior on a power system, which adversely affects the normal operation of electrical or electronic equipment. The choice of monitoring equipment in a survey is also important to ascertain a solution to these power quality problems. A power quality assessment involves gathering data resources; analyzing the data (with reference to power quality standards); then, if problems exist, recommendation of mitigation techniques must be considered. The main objective of the present work is to investigate and mitigate of power quality problems in nuclear installations. Normally electrical power is supplied to the installations via two sources to keep good reliability. Each source is designed to carry the full load. The Assessment of power quality was performed at the nuclear installations for both sources at different operation conditions. The thesis begins with a discussion of power quality definitions and the results of previous studies in power quality monitoring. The assessment determines that one source of electricity was deemed to have relatively good power quality; there were several disturbances, which exceeded the thresholds. Among of them are fifth harmonic, voltage swell, overvoltage and flicker. While the second

Investigation of correlation of LF power modulation of light in natural and artificial illumination situations and acoustic emission

Science.gov (United States)

Kleeberg, Florian P.; Gutzmann, Holger L.; Weyer, Cornelia; Weiß, Jürgen; Dörfler, Joachim; Hahlweg, Cornelius F.

2014-09-01

The present paper is a follow up of a paper presented in 2013 at the Novel Optical Systems conference in the session on Optics and Music. It is derived from an ongoing study on the human perception of combined optical and acoustical periodical stimuli. Originating from problems concerning artificial illumination and certain machinery with coherent optical and acoustical emissions there are effects to be observed which are interesting in the context of occupational medicine. It seems, that acoustic stimuli in the frequency range of the flicker fusion and below might lead to unexpected perceptible effects beyond those of the single stimuli. The effect of infrasound stimuli as a whole body perception seems to be boosted. Because of the difficulties in evaluation of physical and psychological effects of such coherent stimuli in a first step we question if such coherence is perceivable at all. Further, the problem of modulation of optical signals by acoustical signal is concerned. A catalogue of scenarios and 'effects to look for' including measurement concepts is presented and discussed.

Inverted Unified Power Quality Conditioner to compensate overvoltage

Directory of Open Access Journals (Sweden)

Yeison Alberto Garcés Gómez

2017-07-01

Full Text Available Introduction: The use of unified power quality conditioners UPQC in the electric systems can correct waveform distortions in a steady state, like harmonics, flicker, and the power factor. Objective: This paper presents a novel approach for active compensation of overvoltage with a UPQC in dual topology or iUPQC. Methodology: The study it is presented in five stages, the section I shows an introduction and the state of the art, section II presents the unified power quality conditioner UPQC, section III describes the generalized reactive power theory applied to the iUPQC (dual topology, section IV shows the numerical simulations and the results and section V presents the conclusions of the study. Results: The results for the application of the iUPQC to the compensation of overvoltage are proved and compared with the more representative theory related to compensation of harmonics and low power factor. Conclusions: The control algorithm presented for the unified power quality conditioner in dual topology allows to compensate the overvoltage in three-phase systems as well as voltage and current harmonics and the low power factor.

Information Pollution, a Mounting Threat: Internet a Major Causality

Directory of Open Access Journals (Sweden)

Pandita, Ramesh

2014-12-01

Full Text Available The present discourse lasts around, information pollution, causes and concerns of information pollution, internet as a major causality and how it affects the decision making ability of an individual. As, information producers in the process to not to lose the readership of their content, and to cater the information requirements of both the electronic and the print readers, reproduce almost the whole of the printed information in digital form as well. Abundant literature is also equally produced in electronic format only, thereon, sharing this information on hundreds of social networking sites, like, Facebook, Twitter, Blogs, Flicker, Digg, LinkedIn, etc. without attributions to original authors, have created almost a mess of this whole information produced and disseminated. Accordingly, the study discusses about the sources of information pollution, the aspects of unstructured information along with plagiarism. Towards the end of the paper stress has been laid on information literacy, as how it can prove handy in addressing the issue with some measures, which can help in regulating the behaviour of information producers.

Response to acoustic forcing of laminar coflow jet diffusion flames

KAUST Repository

Chrystie, Robin

2014-04-23

Toward the goal of understanding and controlling instability in combustion systems, we present a fundamental characterization of the interaction of the buoyancy-induced instability in flickering flames with forced excitation of fuel supply. Laminar coflow diffusion flames were acoustically forced, whose frequency responses were recorded as a function of excitation frequency and amplitude. The evolving structure of such flames was also examined through the use of video analysis and particle imaging velocimetry (PIV). For specific combinations of excitation frequency and amplitude, the frequency response of the flames was found to couple to that of the forcing, where the contribution of natural puffing frequency disappears. Such instances of coupling exhibited many harmonics of the excitation frequency, related indirectly to the natural puffing frequency. We showed how such harmonics form, through application of PIV, and furthermore unveiled insight into the physics of how the flame couples to the forcing under certain conditions. Our frequency response characterization provides quantitative results, which are of utility for both modeling studies and active-control strategies. Copyright © Taylor & Francis Group, LLC.

Optical and IR light curves of VV Puppis

International Nuclear Information System (INIS)

Szkody, P.; Bailey, J.A.; Hough, J.H.

1983-01-01

We present optical (0.36 to 0.6 μm) light curves with time resolutions of seconds and infrared (IR) (1.25 to 2.2 μm) light curves with time resolutions of minutes for VV Puppis during a high state. The optical light curves show a single hump with largest amplitude in the V filter, while the IR light curves show a double hump sinusoidal variation. Flickering is evident in both the optical and IR light curves, with the largest amplitude in optical B light. Through subtraction of the low state fluxes from our high state values, we obtain a flux distribution of the accretion column which peaks at 0.55 μm and becomes #betta# 2 in the IR, consistent with current cyclotron models. Comparison of the observed IR variations throughout the orbit with the expected variations due to an M4 star heated by an accretion column at an inclination of 66 0 suggests that the IR light is a combination of the secondary star plus contributions from two emitting poles. (author)

Testing the implicit processing hypothesis of precognitive dream experience.

Science.gov (United States)

Valášek, Milan; Watt, Caroline; Hutton, Jenny; Neill, Rebecca; Nuttall, Rachel; Renwick, Grace

2014-08-01

Seemingly precognitive (prophetic) dreams may be a result of one's unconscious processing of environmental cues and having an implicit inference based on these cues manifest itself in one's dreams. We present two studies exploring this implicit processing hypothesis of precognitive dream experience. Study 1 investigated the relationship between implicit learning, transliminality, and precognitive dream belief and experience. Participants completed the Serial Reaction Time task and several questionnaires. We predicted a positive relationship between the variables. With the exception of relationships between transliminality and precognitive dream belief and experience, this prediction was not supported. Study 2 tested the hypothesis that differences in the ability to notice subtle cues explicitly might account for precognitive dream beliefs and experiences. Participants completed a modified version of the flicker paradigm. We predicted a negative relationship between the ability to explicitly detect changes and precognitive dream variables. This relationship was not found. There was also no relationship between precognitive dream belief and experience and implicit change detection. Copyright © 2014 Elsevier Inc. All rights reserved.

Oxidative stress is involved in fatigue induced by overnight deskwork as assessed by increase in plasma tocopherylhydroqinone and hydroxycholesterol.

Science.gov (United States)

Shichiri, Mototada; Harada, Nobuyoshi; Ishida, Noriko; Komaba, Lilian Kaede; Iwaki, Sunao; Hagihara, Yoshihisa; Niki, Etsuo; Yoshida, Yasukazu

2013-12-01

In this study, we examined the relationship between fatigue and plasma concentrations of antioxidants and lipid peroxidation products. Fourteen healthy volunteers performed overnight desk work for 18h then took a nap for 4h. Participants answered questionnaires of subjective symptoms of fatigue (QSSF) and completed a self-assessment of fatigue using a visual analog scale (VAS). At each test time, they underwent a critical flicker frequency (CFF) test and blood samples were collected. Plasma levels of α-tocopherol (αT) decreased and α-tocopherylquinone (αTQ), the oxidation product of αT, increased. The ratio of 7β-hydroxycholesterol (7β-OHCh), the oxidation product of cholesterol, against total cholesterol increased until the end of experiment. αTQ levels correlated with VAS and QSSF scores. The ratio of 7β-OHCh to total cholesterol and the value of CFF showed a significant correlation. From these results, plasma levels of αTQ and 7β-OHCh are useful and objective indicators of fatigue induced by overnight deskwork. Copyright © 2013 Elsevier B.V. All rights reserved.

Assessment of Minimal HE (with emphasis on computerized psychometric tests)

Science.gov (United States)

Kappus, Matthew R; Bajaj, Jasmohan S

2012-01-01

Synopsis Minimal hepatic encephalopathy (MHE) is associated with a high risk of development of overt hepatic encephalopathy, impaired quality of life and driving accidents. The detection of MHE requires specialized testing since it cannot by definition, be diagnosed on standard clinical examination. Psychometric (paper-pencil or computerized or a combination) and neuro-physiological techniques are often used to test for MHE. Paper-pencil psychometric batteries like the Psychometric Hepatic Encephalopathy Score (PHES) have been validated in several countries but do not have US normative values. Computerized tests such as the inhibitory control test (ICT), cognitive drug research system and Scan test have proven useful to diagnose MHE and predict outcomes. The specificity and sensitivity of these tests are similar to the recommended gold standards. Neuro-physiological tests such as the EEG and its interpretations, evoked potentials and Critical Flicker Frequency (CFF) also provide useful information. The diagnosis of MHE is an important issue for clinicians and patients alike and the testing strategies depend on the normative data available, patient comfort and local expertise. PMID:22321464

Comparison Of Power Quality Disturbances Classification Based On Neural Network

Directory of Open Access Journals (Sweden)

Nway Nway Kyaw Win

2015-07-01

Full Text Available Abstract Power quality disturbances PQDs result serious problems in the reliability safety and economy of power system network. In order to improve electric power quality events the detection and classification of PQDs must be made type of transient fault. Software analysis of wavelet transform with multiresolution analysis MRA algorithm and feed forward neural network probabilistic and multilayer feed forward neural network based methodology for automatic classification of eight types of PQ signals flicker harmonics sag swell impulse fluctuation notch and oscillatory will be presented. The wavelet family Db4 is chosen in this system to calculate the values of detailed energy distributions as input features for classification because it can perform well in detecting and localizing various types of PQ disturbances. This technique classifies the types of PQDs problem sevents.The classifiers classify and identify the disturbance type according to the energy distribution. The results show that the PNN can analyze different power disturbance types efficiently. Therefore it can be seen that PNN has better classification accuracy than MLFF.

Lighting Quality Affects Eyestrain of Operators at Sorting Station in Beverage Industry

Science.gov (United States)

Anizar; Erwin

2017-03-01

This study observes sorters’ performance in two beverage industries whose job is to separate defect products found. Sorters observe bottles quality and beverage quality continuously, therefore requiring more focused eyes which makes eyes’ load heavier. Sorters’ eyestrain causes more defect products pass the selection. In this study, measurement is conducted toward ilumintation, operators’ time response, and defect products that pass the selection. Measurement is hold in 2 beverage industries for four days with four measurements per day, twice in the morning and twice in the afternoon. Ilumination is measured with 4 in 1 environmental meter in grid 1m x 1m, while operators’ time response is measured with Flicker Fusion. Illuminance is generally higher in the morning than in the evening, but still under the standard of Indonesia. Overall, sorters’ time response is higher in the morning than in the afternoon. Higher time response shows that operators experiencing lower fatigue than lower time response. The sorting duration also affects operators’ time response and defect products which pass the selection.

The PS Booster hits 40

CERN Multimedia

Joannah Caborn Wengler

2012-01-01

Many accelerators’ "round" birthdays are being celebrated at CERN these days – the PS turned 50 in 2009, the SPS was 35 in 2011, and this year it's the turn of the PS Booster to mark its 40th anniversary. Originally designed to accelerate 1013 protons to 800 MeV, it has far exceeded its initial design performance over the years.   The PS Booster in the 1970s. Imagine the scene: a group of accelerator physicists staring expectantly at a monitor, when suddenly a shout of joy goes up as a signal flickers across the screen. Does that sound familiar? Well, turn the clock back 40 years (longer hair, wider trouser legs) and you have the situation at the PS Booster on 26 May 1972. On that day, beam was injected into the Booster for the first time. “It was a real buzz,” says Heribert Koziol, then Chairman of the Running-in Committee. “We were very happy – and also a little relieved – when the beam finally...

Controlled power delivery for super-resolution imaging of biological samples using digital micromirror device

Science.gov (United States)

Valiya Peedikakkal, Liyana; Cadby, Ashley

2017-02-01

Localization based super resolution images of a biological sample is generally achieved by using high power laser illumination with long exposure time which unfortunately increases photo-toxicity of a sample, making super resolution microscopy, in general, incompatible with live cell imaging. Furthermore, the limitation of photobleaching reduces the ability to acquire time lapse images of live biological cells using fluorescence microscopy. Digital Light Processing (DLP) technology can deliver light at grey scale levels by flickering digital micromirrors at around 290 Hz enabling highly controlled power delivery to samples. In this work, Digital Micromirror Device (DMD) is implemented in an inverse Schiefspiegler telescope setup to control the power and pattern of illumination for super resolution microscopy. We can achieve spatial and temporal patterning of illumination by controlling the DMD pixel by pixel. The DMD allows us to control the power and spatial extent of the laser illumination. We have used this to show that we can reduce the power delivered to the sample to allow for longer time imaging in one area while achieving sub-diffraction STORM imaging in another using higher power densities.

VARIABILITY OF OPTICAL COUNTERPARTS IN THE CHANDRA GALACTIC BULGE SURVEY

Energy Technology Data Exchange (ETDEWEB)

Britt, C. T.; Hynes, R. I.; Johnson, C. B.; Baldwin, A.; Collazzi, A.; Gossen, L. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, LA 70803-4001 (United States); Jonker, P. G.; Torres, M. A. P. [SRON, Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands); Nelemans, G. [Department of Astrophysics, IMAPP, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen (Netherlands); Maccarone, T. [Department of Physics, Texas Tech University, Box 41051, Science Building, Lubbock, TX 79409-1051 (United States); Steeghs, D.; Greiss, S. [Astronomy and Astrophysics, Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Heinke, C. [Department of Physics, University of Alberta, CCIS 4-183, Edmonton, AB T6G 2E1 (Canada); Bassa, C. G. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom); Villar, A. [Department of Physics, Massachussettes Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); Gabb, M. [Department of Physics, Florida Atlantic University, 777 Glades Road, Boca Raton, FL 33431-0991 (United States)

2014-09-01

We present optical light curves of variable stars consistent with the positions of X-ray sources identified with the Chandra X-ray Observatory for the Chandra Galactic Bulge Survey (GBS). Using data from the Mosaic-II instrument on the Blanco 4 m Telescope at CTIO, we gathered time-resolved photometric data on timescales from ∼2 hr to 8 days over the 3/4 of the X-ray survey containing sources from the initial GBS catalog. Among the light curve morphologies we identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long period variables, spotted stars, and flare stars. Eighty-seven percent of X-ray sources have at least one potential optical counterpart. Twenty-seven percent of these candidate counterparts are detectably variable; a much greater fraction than expected for randomly selected field stars, which suggests that most of these variables are real counterparts. We discuss individual sources of interest, provide variability information on candidate counterparts, and discuss the characteristics of the variable population.

Farewell to a magnetic year at CERN

CERN Multimedia

2006-01-01

For the past four years, successive teams of Indian technical engineers have been spending a year each at CERN to test magnets for the LHC. As the operation approaches completion, three individuals tell us their experiences away from home. Some of the Indian technical engineers in the SM18 test hall. On a dark autumn night, a special celebration took place inside a small room in the vast test hall of SM18, the magnet test facility for the LHC in Saint Genis Pouilly. This may well be the last time this particular soirée at CERN will be juxtaposed with the tranquillity of the French countryside. Inside, beautifully arranged candles flickered with a warm glow to illuminate the faces of jovial guests. Welcome to Diwali, the Indian Festival of Lights. For the past four years, there has been a community of Indian technical engineers at SM18. They brought with them their families and traditions, adding an Indian flavour to CERN's cultural mix. The SM18 community celebrated Diwali with a party, and lit candles to r...

Statistical analysis and dimensioning of a wind farm energy storage system

Directory of Open Access Journals (Sweden)

Waśkowicz Bartosz

2017-06-01

Full Text Available The growth in renewable power generation and more strict local regulations regarding power quality indices will make it necessary to use energy storage systems with renewable power plants in the near future. The capacity of storage systems can be determined using different methods most of which can be divided into either deterministic or stochastic. Deterministic methods are often complicated with numerous parameters and complex models for long term prediction often incorporating meteorological data. Stochastic methods use statistics for ESS (Energy Storage System sizing, which is somewhat intuitive for dealing with the random element of wind speed variation. The proposed method in this paper performs stabilization of output power at one minute intervals to reduce the negative influence of the wind farm on the power grid in order to meet local regulations. This paper shows the process of sizing the ESS for two selected wind farms, based on their levels of variation in generated power and also, for each, how the negative influences on the power grid in the form of voltage variation and a shortterm flicker factor are decreased.

MUON DETECTORS: RPC

CERN Document Server

G. Iaselli

The RPC group has invested a large effort in the study of trigger spikes observed during CRAFT data taking. The chambers are susceptible to noise generated by the flickering of fluorescent and projector lamps in the cavern (with magnetic field on). Soon after the end of CRAFT, it was possible to reproduce the phenomena using a waveform generator and to study possible modifications to be implemented in the grounding schema. Hardware actions have been already taken in order to reduce the detector sensitivity: star washers on the chamber front panels and additional shielding have been added where possible. During the shutdown maintenance activity many different problems were tackled on the barrel part. A few faulty high voltage connector/cable problems were fixed; now only two RPC chambers are left with single-gap mode operation. One chamber in YB+2 was replaced due to gas leakage. All the front-end electronic boards were replaced in 3 chambers (stations MB2 and MB3 in YB-2), that had been damaged after the coo...

Offshore wind farm Bockstigen - installation and operation experience

Energy Technology Data Exchange (ETDEWEB)

Lange, B [Risoe National Lab., Wind Energy and Atmospheric Physics Dept., Roskilde (Denmark); Aagaard, E; Andersen, P E; Moeller, A [Wind World af 1997 A/S, Noerresundby (Denmark); Niklasson, S; Wickman, A [Vindkompaniet, Degerhamn (Sweden)

1999-03-01

The first Swedish offshore wind farm Bockstigen is operating since March 1998 near the coast of Gotland. It was built as a demonstration project by the Swedish wind farm developer Vindkompaniet, the Danish wind turbine manufacturer Wind World and the British offshore construction company Seacore and partly funded under the EU-THERMIE program. Bockstigen is the fourth offshore wind farm world-wide. While at previous wind farms the main emphasis laid on the demonstration of the technical feasibility of offshore wind energy utilisation, Bockstigen was aimed at demonstrating its economic viability. A number of innovative concepts have been employed: Drilled monopile foundations were used to save costs. A new construction method has been applied making use of a jack-up barge. A new control system for the turbines and the whole wind farm was developed, which controls the maximum power output, the flicker and the reactive power consumption depending on online measurements of the actual grid state. These new developments have been implemented successfully. A substantial cost reduction compared to previous offshore projects could be achieved. (au)

Cue competition affects temporal dynamics of edge-assignment in human visual cortex.

Science.gov (United States)

Brooks, Joseph L; Palmer, Stephen E

2011-03-01

Edge-assignment determines the perception of relative depth across an edge and the shape of the closer side. Many cues determine edge-assignment, but relatively little is known about the neural mechanisms involved in combining these cues. Here, we manipulated extremal edge and attention cues to bias edge-assignment such that these two cues either cooperated or competed. To index their neural representations, we flickered figure and ground regions at different frequencies and measured the corresponding steady-state visual-evoked potentials (SSVEPs). Figural regions had stronger SSVEP responses than ground regions, independent of whether they were attended or unattended. In addition, competition and cooperation between the two edge-assignment cues significantly affected the temporal dynamics of edge-assignment processes. The figural SSVEP response peaked earlier when the cues causing it cooperated than when they competed, but sustained edge-assignment effects were equivalent for cooperating and competing cues, consistent with a winner-take-all outcome. These results provide physiological evidence that figure-ground organization involves competitive processes that can affect the latency of figural assignment.

Color coded multiple access scheme for bidirectional multiuser visible light communications in smart home technologies

Science.gov (United States)

Tiwari, Samrat Vikramaditya; Sewaiwar, Atul; Chung, Yeon-Ho

2015-10-01

In optical wireless communications, multiple channel transmission is an attractive solution to enhancing capacity and system performance. A new modulation scheme called color coded multiple access (CCMA) for bidirectional multiuser visible light communications (VLC) is presented for smart home applications. The proposed scheme uses red, green and blue (RGB) light emitting diodes (LED) for downlink and phosphor based white LED (P-LED) for uplink to establish a bidirectional VLC and also employs orthogonal codes to support multiple users and devices. The downlink transmission for data user devices and smart home devices is provided using red and green colors from the RGB LEDs, respectively, while uplink transmission from both types of devices is performed using the blue color from P-LEDs. Simulations are conducted to verify the performance of the proposed scheme. It is found that the proposed bidirectional multiuser scheme is efficient in terms of data rate and performance. In addition, since the proposed scheme uses RGB signals for downlink data transmission, it provides flicker-free illumination that would lend itself to multiuser VLC system for smart home applications.

Visual search and emotion: how children with autism spectrum disorders scan emotional scenes.

Science.gov (United States)

Maccari, Lisa; Pasini, Augusto; Caroli, Emanuela; Rosa, Caterina; Marotta, Andrea; Martella, Diana; Fuentes, Luis J; Casagrande, Maria

2014-11-01

This study assessed visual search abilities, tested through the flicker task, in children diagnosed with autism spectrum disorders (ASDs). Twenty-two children diagnosed with ASD and 22 matched typically developing (TD) children were told to detect changes in objects of central interest or objects of marginal interest (MI) embedded in either emotion-laden (positive or negative) or neutral real-world pictures. The results showed that emotion-laden pictures equally interfered with performance of both ASD and TD children, slowing down reaction times compared with neutral pictures. Children with ASD were faster than TD children, particularly in detecting changes in MI objects, the most difficult condition. However, their performance was less accurate than performance of TD children just when the pictures were negative. These findings suggest that children with ASD have better visual search abilities than TD children only when the search is particularly difficult and requires strong serial search strategies. The emotional-social impairment that is usually considered as a typical feature of ASD seems to be limited to processing of negative emotional information.

Responsive upper limb and cognitive fatigue measures during light precision work: an 8-hour simulated micro-pipetting study.

Science.gov (United States)

Yung, Marcus; Wells, Richard P

2017-07-01

Many contemporary occupations are characterised by long periods of low loads. These lower force levels, which are relevant to the development of work-related musculoskeletal disorders, are usually not the focus of fatigue studies. In studies that did measure fatigue in light manual or precision work, within and between measurement responses were inconsistent. The aim of this study was to identify fatigue measures that were responsive at lower force levels (fatigue measures, reflecting both neuromuscular and cognitive mechanisms, was measured during a light precision micro-pipetting task performed by 11 participants. Nine measures were found to be significantly responsive over the 8-h period, including: ratings of perceived fatigue, postural tremor, blink frequency and critical flicker fusion frequency threshold. Common field measures, specifically electromyography RMS amplitude and maximum voluntary contractions, did not lead to extraordinary time effects. Practitioner summary: The findings provide insight towards the responsiveness of a complementary set of field usable fatigue measures at low work intensities Although commonly used measures did not reveal significant increases in fatigue, nine alternative measures were significantly responsive over the 8-h period.

Subjective and objective symptoms of psychical load in nuclear power plant operators in connection with shift operation

International Nuclear Information System (INIS)

Kozeny, J.; Prochazkova, Z.

1992-01-01

A group of 56 operators (mean age=34.6 years, S.D. 3.4 year, range=30-40 years; university graduates of technical direction) in a nuclear power plant was followed during the morning, afternoon and night shift from the standpoint of subjective symptoms (an evaluation scale assessed at the beginning, in the middle and at the end of the shift) and objective symptoms (critical flicker frequency determined at the same time) of the psychical load. No significant differences were found by multivariation analysis between subjective perception of the work load and its objective reflection. The night shift, where the load lies particularly in the monotony of stimuli, appears to exert a higher psychical load aimed at maintaining mental activity when compared with the afternoon and morning shift. In contrast to subjective assessment of the psychical condition where the data fluctuated during the whole shift, the psychical activity reflected in the objective data, decreased until the middle of the shift when stabilization occurred. (author) 1 tab., 8 refs

A research project to encourage system-compatible design of end-use appliances

International Nuclear Information System (INIS)

Dorr, D.; Key, T.; Sitzlar, G.

1995-01-01

Cooperative system compatibility research sponsored by the Canadian Electrical Association (CEA) and the Electric Power Research Institute (EPRI) for improving appliance performance deficiencies was described. Power producer and end-user compatibility concerns was addressed through the development of a System Compatibility Research Project. A list of project tasks was provided. The CEA and EPRI initiated a project to establish flicker response of various lighting systems, which included physical tests. Results of this project were presented and discussed. The incentives for developing switch mode power supplies with enhanced immunity to voltage fluctuations and short interruptions was discussed. It was concluded that power quality studies currently underway will provide designers with a profile of the expected utility environment for their products. System compatibility research will identify areas that should be addressed by standards bodies so that designers can apply applicable criteria objectives early in the appliance design process. These efforts were expected to encourage appropriate manufacturer criteria for compatibility by convincing buyers and sellers that there is a real pay back for this investment. 13 refs., 6 figs., 4 tabs

Macular Carotenoids, Aerobic Fitness, and Central Adiposity Are Associated Differentially with Hippocampal-Dependent Relational Memory in Preadolescent Children.

Science.gov (United States)

Hassevoort, Kelsey M; Khazoum, Sarah E; Walker, John A; Barnett, Sasha M; Raine, Lauren B; Hammond, Billy R; Renzi-Hammond, Lisa M; Kramer, Arthur F; Khan, Naiman A; Hillman, Charles H; Cohen, Neal J

2017-04-01

To examine the associations of macular pigment carotenoids (lutein, meso-zeaxanthin, and zeaxanthin), aerobic fitness, and central adiposity with hippocampal-dependent relational memory in prepubescent children. Children between 7 and 10 years of age (n = 40) completed a task designed to assess relational memory performance and participated in aerobic fitness, adiposity, and macular pigment optical density (MPOD) assessment. Aerobic fitness was assessed via a modified Balke treadmill protocol designed to measure maximal oxygen volume. Central adiposity was assessed via dual-energy x-ray absorptiometry. MPOD was measured psychophysically by the use of customized heterochromatic flicker photometry. Statistical analyses included correlations and hierarchical linear regression. Aerobic fitness and MPOD were associated negatively with relational memory errors (P memory errors (P memory performance even after we accounted for aerobic fitness (β = -0.388, P = .007). Even after we adjusted for aerobic fitness and central adiposity, factors known to relate to hippocampal-dependent memory, MPOD positively and significantly predicted hippocampal-dependent memory performance. ClinicalTrials.gov: NCT01619826. Copyright © 2017 Elsevier Inc. All rights reserved.

A Profile of an ‘A’ List Homo –Habitus, Attitude, Boredom and The End of Enjoyment

Directory of Open Access Journals (Sweden)

Sasho Alexander Lambevski

2015-05-01

Full Text Available Embodying signifiers of silent suffering, frequently envenomed by envy disguised as patronising pity, enraged as a result of admiration never returned, duped by their naïve belief in gay (capitalist Eden, stress-ridden, moving through a psychosocial reality that almost never fails to disappoint, split between a deadly wish to speak in monotone with their larynxes, bodies and dicks, and a little flicker that tells them to resists this urge, too many homo men express, in the guise of the composite character I describe below, the emotional battleground created by the new bourgeoisie’s deployment of the breathtakingly beautiful masculine homo male body as a sign/image vehicle in asserting its own social domination in a late capitalist society. The character I develop here can be read as a simulation and fabulation of the homonormative new bourgeois self as a syndrome with a range of affective cripplings coming from the technologically assisted channelling of homosexual desire via the mass circulation of the imaginary of the homo new bourgeoisie. 

Acute effects of temazepam and nitrazepam on psychomotor skills and memory

Science.gov (United States)

Liljequist, Raija; Mattila, M. J.

1979-01-01

1 Twelve pretrained healthy students ingested temazepam 10 mg, nitrazepam 20 mg and placebo 10 mg, each double blind at 1-week intervals in randomized order. Reactive and coordinative skills and critical flicker fusion were measured before each drug intake and 1, 2, 3, 6 and 8 h after it. Short-term memory and paired association learning were measured at 1, 3 and 8 hours. 2 Nitrazepam 10 mg increased reaction and coordination errors and also impaired learning and memory. Temazepam 10 mg impaired coordinative skills; otherwise it differed from nitrazepam but hardly from placebo. Temazepam 20 mg impaired coordination, and learning and memory. Both temazepam 20 mg and nitrazepam 10 mg were experienced as being sedative. All drug effects were clearest during the first 3 h, whereas nitrazepam also impaired learning at 8 hours. 3 The psychomotor responses to drugs were modified by a sequence effect (not at zero tests) which varied depending on the drug and parameter. In multivariance analysis it was included to reveal drug effects. 4 Temazepam 20 mg seems suitable as a hypnotic.

Limits to the usability of iconic memory.

Science.gov (United States)

Rensink, Ronald A

2014-01-01

Human vision briefly retains a trace of a stimulus after it disappears. This trace-iconic memory-is often believed to be a surrogate for the original stimulus, a representational structure that can be used as if the original stimulus were still present. To investigate its nature, a flicker-search paradigm was developed that relied upon a full scan (rather than partial report) of its contents. Results show that for visual search it can indeed act as a surrogate, with little cost for alternating between visible and iconic representations. However, the duration over which it can be used depends on the type of task: some tasks can use iconic memory for at least 240 ms, others for only about 190 ms, while others for no more than about 120 ms. The existence of these different limits suggests that iconic memory may have multiple layers, each corresponding to a particular level of the visual hierarchy. In this view, the inability to use a layer of iconic memory may reflect an inability to maintain feedback connections to the corresponding representation.

Limits to the Usability of Iconic Memory

Directory of Open Access Journals (Sweden)

Ronald A. Rensink

2014-08-01

Full Text Available Human vision briefly retains a trace of a stimulus after it disappears. This trace—iconic memory—is often believed to be a surrogate for the original stimulus, a representational structure that can be used as if the original stimulus were still present. To investigate its nature, a flicker-search paradigm was developed that relied upon a full scan (rather than partial report of its contents. Results show that for visual search it can indeed act as a surrogate, with little cost for alternating between visible and iconic representations. However, the duration over which it can be used depends on the type of task: some tasks can use iconic memory for at least 240 ms, others for only about 190 ms, while others for no more than about 120 ms. The existence of these different limits suggests that iconic memory may have multiple layers, each corresponding to a particular level of the visual hierarchy. In this view, the inability to use a layer of iconic memory may reflect an inability to maintain feedback connections to the corresponding representation.

Printable candlelight-style organic light-emitting diode

Science.gov (United States)

Jou, J. H.; Singh, M.; Song, W. C.; Liu, S. H.

2017-06-01

Candles or oil lamps are currently the most friendly lighting source to human eyes, physiology, ecosystems, artifacts, environment, and night skies due to their blue light-less emission. Candle light also exhibits high light-quality that provides visual comfort. However, they are relatively low in power efficacy (0.3 lm/W), making them energy-wasting, besides having problems like scorching hot, burning, catching fire, flickering, carbon blacking, oxygen consuming, and release of green house gas etc. In contrast, candlelight organic light-emitting diode (OLED) can be made blue-hazard free and energy-efficient. The remaining challenges are to maximize its light-quality and enable printing feasibility, the latter of which would pave a way to cost-effective manufacturing. We hence demonstrate herein the design and fabrication of a candlelight OLED via wet-process. From retina protection perspective, its emission is 13, 12 and 8 times better than those of the blue-enriched white CFL, LED and OLED. If used at night, it is 9, 6 and 4 times better from melatonin generation perspective.

Impaired temporal contrast sensitivity in dyslexics is specific to retain-and-compare paradigms.

Science.gov (United States)

Ben-Yehudah, G; Sackett, E; Malchi-Ginzberg, L; Ahissar, M

2001-07-01

Developmental dyslexia is a specific reading disability that affects 5-10% of the population. Recent studies have suggested that dyslexics may experience a deficit in the visual magnocellular pathway. The most extensively studied prediction deriving from this hypothesis is impaired contrast sensitivity to transient, low-luminance stimuli at low spatial frequencies. However, the findings are inconsistent across studies and even seemingly contradictory. In the present study, we administered several different paradigms for assessing temporal contrast sensitivity, and found both impaired and normal contrast sensitivity within the same group of dyslexic participants. Under sequential presentation, in a temporal forced choice paradigm, dyslexics showed impaired sensitivity to both drifting and flickering gratings. However, under simultaneous presentation, with a spatial forced choice paradigm, dyslexics' sensitivity did not differ from that of the controls. Within each paradigm, dyslexics' sensitivity was poorer at higher temporal frequencies, consistent with the magnocellular hypothesis. These results suggest that a basic perceptual impairment in dyslexics may be their limited ability to retain-and-compare perceptual traces across brief intervals.

Custom power - the utility solution to distribution power quality

Energy Technology Data Exchange (ETDEWEB)

Woodley, N H [Westinghouse Electric Corp., Pittsburgh, PA (United States)

1997-04-01

The design of custom power products for electric power distribution system was discussed. Problems with power quality that result in loss of production to critical processes are costly and create a problem for the customer as well as the electric utility. Westinghouse has developed power quality improvement equipment for customers and utilities, using new technologies based on power electronics concepts. The Distribution Static Compensator (DSTATCOM) is a fast response, solid-state power controller that provides flexible voltage control for improving power quality at the point of connection to the utility`s 4.16 to 69 kV distribution feeder. STATCOM is a larger version of the DSTATCOM that can be used to solve voltage flicker problems caused by electric arc furnaces. Westinghouse has also developed a Dynamic Voltage Restorer (DVR) which protects a critical customer plant load from power system voltage disturbances. Solid-State Breakers (SSB) have also been developed which offer a solution to many of the distribution system problems that result in voltage sags, swells, and power outages. 6 refs., 8 figs.

Assessment of Power Quality Problems for TRIGA PUSPATI Reactor (RTP)

International Nuclear Information System (INIS)

Mohd Fazli Zakaria; Ramachandaramurthy, V.K.

2016-01-01

The electrical power systems are exposed to different types of power quality disturbances. Investigation and monitoring of power quality is necessary to maintain accurate operation of sensitive equipment especially for nuclear installations. This paper will discuss the power quality problems observed at the electrical sources of PUSPATI TRIGA Reactor (RTP). Assessment of power quality requires the identification of any anomalous behavior on a power system, which adversely affects the normal operation of electrical or electronic equipment. A power quality assessment involves gathering data resources; analyzing the data (with reference to power quality standards) then, if problems exist, recommendation of mitigation techniques must be considered. Field power quality data is collected by power quality recorder and analyzed with reference to power quality standards. Normally the electrical power is supplied to the RTP via two sources in order to keep a good reliability where each of them is designed to carry the full load. The assessment of power quality during reactor operation was performed for both electrical sources. There were several disturbances such as voltage harmonics and flicker that exceeded the thresholds. (author)

On-Demand Sensor Node Wake-Up Using Solar Panels and Visible Light Communication

Directory of Open Access Journals (Sweden)

Carolina Carrascal

2016-03-01

Full Text Available To significantly reduce, or eliminate completely, the energy waste caused by the standby (idle mode of wireless sensor nodes, we propose a novel on-demand wake-up system, which allows the nodes to be put into sleep mode unless their activation is truly necessary. Although there have been many studies proposing RF-based wake-up radio systems, in this work, we develop the first visible light communication (VLC-based wake-up system. The developed system can extend the existing VLC systems and can be exploited to derive new application areas such as VLC tags. The system uses an off-the-shell indoor solar panel as receptor device of the wake-up signal as well as for energy harvesting purposes, through which it is able to harvest enough energy for its autonomous work. The design, implementation details and the experimental evaluation results are presented, which include flickering characterization and wake-up range evaluations. The results show that the developed system achieve reasonable wake-up distances for indoor environments, mainly where the use of VLC systems are considered.

Antigen-antibody biorecognition events as discriminated by noise analysis of force spectroscopy curves.

Science.gov (United States)

Bizzarri, Anna Rita; Cannistraro, Salvatore

2014-08-22

Atomic force spectroscopy is able to extract kinetic and thermodynamic parameters of biomolecular complexes provided that the registered unbinding force curves could be reliably attributed to the rupture of the specific complex interactions. To this aim, a commonly used strategy is based on the analysis of the stretching features of polymeric linkers which are suitably introduced in the biomolecule-substrate immobilization procedure. Alternatively, we present a method to select force curves corresponding to specific biorecognition events, which relies on a careful analysis of the force fluctuations of the biomolecule-functionalized cantilever tip during its approach to the partner molecules immobilized on a substrate. In the low frequency region, a characteristic 1/f (α) noise with α equal to one (flickering noise) is found to replace white noise in the cantilever fluctuation power spectrum when, and only when, a specific biorecognition process between the partners occurs. The method, which has been validated on a well-characterized antigen-antibody complex, represents a fast, yet reliable alternative to the use of linkers which may involve additional surface chemistry and reproducibility concerns.

Math Model and Calculation Analysis of Inter-harmonic of Double PWM Speed Control System in Distribution Network

Directory of Open Access Journals (Sweden)

Yang Wen-Huan

2014-11-01

Full Text Available Aiming at the problem that the distribution network voltage will fluctuate because of the inter-harmonic currents injected into the network by double PWM speed control system when regulating the speed of the asynchronous motor, we established the inter-harmonic current math model of double PWM speed control system according to switching function based on a real bridge crane. The distribution law of the inter-harmonic is got by calculating the grid-side currents and their spectrum while letting the motor run at different quadrants and frequencies. The result which is verified by simulation and experiment shows that the content of the inter harmonic currents is more than that of harmonic currents in double PWM speed control system, the frequency of the inter harmonics of the grid-side current mainly focus on the scope lower than the fundamental frequency, and when the motor runs at low frequencies, the THD of the grid-side current is high. The result has verified the reason why the voltage of a bridge crane distribution system of a deepwater port in Shanghai flickers.

FliPer: checking the reliability of global seismic parameters from automatic pipelines

Science.gov (United States)

Bugnet, L.; García, R. A.; Davies, G. R.; Mathur, S.; Corsaro, E.

2017-12-01

Our understanding of stars through asteroseismic data analysis is limited by our ability to take advantage of the huge amount of observed stars provided by space missions such as CoRoT, \\keplerp, \\ktop, and soon TESS and PLATO. Global seismic pipelines provide global stellar parameters such as mass and radius using the mean seismic parameters, as well as the effective temperature. These pipelines are commonly used automatically on thousands of stars observed by K2 for 3 months (and soon TESS for at least ˜ 1 month). However, pipelines are not immune from misidentifying noise peaks and stellar oscillations. Therefore, new validation techniques are required to assess the quality of these results. We present a new metric called FliPer (Flicker in Power), which takes into account the average variability at all measured time scales. The proper calibration of \\powvar enables us to obtain good estimations of global stellar parameters such as surface gravity that are robust against the influence of noise peaks and hence are an excellent way to find faults in asteroseismic pipelines.

VLC-beacon detection with an under-sampled ambient light sensor

Science.gov (United States)

Green, Jacob; Pérez-Olivas, Huetzin; Martínez-Díaz, Saúl; García-Márquez, Jorge; Domínguez-González, Carlos; Santiago-Montero, Raúl; Guan, Hongyu; Rozenblat, Marc; Topsu, Suat

2017-08-01

LEDs will replace in a near future the current worldwide lighting mainly due to their low production-cost and energy-saving assets. Visible light communications (VLC) will turn gradually the existing lighting network into a communication network. Nowadays VLC transceivers can be found in some commercial centres in Europe; some of them broadcast continuously an identification tag that contains its coordinate position. In such a case, the transceiver acts as a geolocation beacon. Nevertheless, mobile transceivers represent a challenge in the VLC communication chain, as smartphones have not integrated yet a VLC customized detection stage. In order to make current smartphones capable to detect VLC broadcasted signals, their Ambient Light Sensor (ALS) is adapted as a VLC detector. For this to be achieved, lighting transceivers need to adapt their modulation scheme. For instance, frequencies representing start bit, 1, and 0 logic values can be set to avoid flicker from illumination and to permit detecting the under-sampled signal. Decoding the signal requires a multiple steps real-time signal processing as shown here.

On-Demand Sensor Node Wake-Up Using Solar Panels and Visible Light Communication.

Science.gov (United States)

Carrascal, Carolina; Demirkol, Ilker; Paradells, Josep

2016-03-22

To significantly reduce, or eliminate completely, the energy waste caused by the standby (idle) mode of wireless sensor nodes, we propose a novel on-demand wake-up system, which allows the nodes to be put into sleep mode unless their activation is truly necessary. Although there have been many studies proposing RF-based wake-up radio systems, in this work, we develop the first visible light communication (VLC)-based wake-up system. The developed system can extend the existing VLC systems and can be exploited to derive new application areas such as VLC tags. The system uses an off-the-shell indoor solar panel as receptor device of the wake-up signal as well as for energy harvesting purposes, through which it is able to harvest enough energy for its autonomous work. The design, implementation details and the experimental evaluation results are presented, which include flickering characterization and wake-up range evaluations. The results show that the developed system achieve reasonable wake-up distances for indoor environments, mainly where the use of VLC systems are considered.